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Digital Camera Patent Abstract
A digital camera body to which a lens unit having an image taking
optical system is attachable. The camera body has a shake detector
detecting a camera shake on the digital camera and outputting a
shake detection signal, a blur compensator compensates for a blur,
due to the camera shake, of a subject light image projected onto
an image capturing surface of an image sensor provided in the camera
body, based on an inputted blur compensation amount, a focal length
deriver obtaining an overall focal length of the image taking optical
system, by use of the information on the focal length obtained from
the lens unit, and a blur compensation controller deriving the blur
compensation amount for compensating for the blur based on the overall
focal length of the image taking optical system and the shake detection
signal, and outputting the blur compensation amount to the blur
compensator.
Digital Camera Patent Claims
1. A digital camera comprising: a camera body; and a lens unit detachable
from said camera body and having an image taking optical system;
said camera body further comprising: a communication portion configured
to receive an information on a focal length of the image taking
optical system from the lens unit; a shake detector that detects
a camera shake on the digital camera, and outputs a shake detection
signal; a blur compensator configured to receive a blur compensation
amount and compensates for a blur, due to the camera shake, of a
subject light image projected onto an image capturing surface of
an image sensor provided in the camera body, based on the received
blur compensation amount; a focal length deriver provided configured
to obtain an overall focal length of the image taking optical system,
by use of the information on the focal length obtained by the communication
portion; and a blur compensation controller configured to derive
the blur compensation amount for compensating for the blur based
on the overall focal length of the image taking optical system obtained
by the focal length deriver and the shake detection signal outputted
from the shake detector, and outputs the blur compensation amount
to the blur compensator.
2. A digital camera as claimed in claim 1, wherein the image taking
optical system in the lens unit includes a magnification varying
optical system.
3. A digital camera as claimed in claim 1, wherein the blur compensation
amount includes a blur compensation direction.
4. A digital camera as claimed in claim 3, wherein the blur compensator
includes the image sensor having the image capturing surface on
an image forming surface thereof, and a driver that drives the image
sensor in two orthogonal directions on the image forming surface,
and said driver performs blur compensation by driving the image
sensor based on the blur compensation amount and the blur compensation
direction outputted from the blur compensation controller.
5. A digital camera as claimed in claim 3, wherein the blur compensator
includes an optical element to optically compensate for blur.
6. A digital camera as claimed in claim 2, wherein the focal length
deriver further comprising: a calculator that calculates the overall
focal length of the image taking optical system by use of a predetermined
arithmetic expression from a coefficient and the currently set focal
length by the magnification varying optical system of the lens unit
when the lens unit is attached to the camera body.
7. A digital camera as claimed in claim 6, wherein the focal length
deriver further comprising: a coefficient storage that stores the
coefficient set according to the focal length settable by the magnification
varying optical system, for each lens unit attachable to the camera
body; and wherein said calculator of the focal length deriver reads
out, when the lens unit whose coefficient is stored in the coefficient
storage is attached to the camera body, the coefficient corresponding
to the focal length currently set by the magnification varying optical
system of the lens unit from the coefficient storage, and calculates
the overall focal length of the image taking optical system by use
of the predetermined arithmetic expression from the coefficient
and the currently set focal length.
8. A digital camera as claimed in claim 6, wherein the lens unit
further comprising: a coefficient storage that stores a coefficient
set according to the focal length settable by the magnification
varying optical system; and a coefficient outputter that outputs
the coefficient stored in the coefficient storage to the focal length
deriver when the lens unit is attached to the camera body, wherein
the calculator of the focal length deriver calculates the overall
focal length of the image taking optical system by use of the predetermined
arithmetic expression from the coefficient outputted from the coefficient
outputter and the focal length currently set by the magnification
varying optical system of the lens unit when the lens unit is attached
to the camera body.
9. A digital camera as claimed in claim 6, wherein the image taking
optical system is provided with a focus adjustment optical system
for performing focus adjustment, the predetermined arithmetic expression
includes a driving amount of the focus adjustment optical system
as a variable, and the calculator calculates the overall focal length
of the image taking optical system by use of the predetermined arithmetic
expression from the coefficient, the currently set focal length
by the magnification varying optical system, and the driving amount
of the focus adjustment optical system.
10. A digital camera as claimed in claim 9, wherein the camera
body further comprising: a second driver that drives the focus adjustment
optical system in a direction of an optical axis; a second driving
controller that controls an operation of the second driver; and
a driving amount outputter that outputs, to the focal length deriver,
information on a driving amount of the focus adjustment optical
system driven by the second driver under the control by the second
driving controller when the lens unit having the focus adjustment
optical system driven by the second driver and the second driving
controller is attached to the camera body.
11. A digital camera as claimed in claim 9, wherein the lens unit
further comprising: a second driver that drives the focus adjustment
optical system in a direction of an optical axis; a second driving
controller that controls an operation of the second driver; and
a driving amount outputter that outputs, to the focal length deriver,
information on a driving amount of the focus adjustment optical
system driven by the second driver under the control by the second
driving controller when the lens unit is attached to the camera
body.
12. A digital camera body to which a lens unit having an image
taking optical system is attachable, said camera body comprising:
a communication portion configured to receive an information on
a focal length of the image taking optical system from the lens
unit; a shake detector that detects a camera shake on the digital
camera, and outputs a shake detection signal; a blur compensator
configured to receive a blur compensation amount and compensates
for a blur, due to the camera shake, of a subject light image projected
onto an image capturing surface of an image sensor provided in the
camera body, based on the received blur compensation amount; a focal
length deriver configured to obtain an overall focal length of the
image taking optical system, by use of the information on the focal
length obtained by the communication portion; and a blur compensation
controller configured to derive the blur compensation amount for
compensating for the blur based on the overall focal length of the
image taking optical system obtained by the focal length deriver
and the shake detection signal outputted from the shake detector,
and outputs the blur compensation amount to the blur compensator.
13. A digital camera body as claimed in claim 12, wherein the image
taking optical system in the lens unit includes a magnification
varying optical system.
14. A digital camera body as claimed in claim 12, wherein the blur
compensation amount includes a blur compensation direction.
15. A digital camera body as claimed in claim 14, wherein the blur
compensator includes the image sensor having the image capturing
surface on an image forming surface thereof, and a driver that drives
the image sensor in two orthogonal directions on the image forming
surface, and said driver performs blur compensation by driving the
image sensor based on the blur compensation amount and the blur
compensation direction outputted from the blur compensation controller.
16. A digital camera as claimed in claim 14, wherein the blur compensator
includes an optical element to optically compensate for blur.
17. A digital camera as claimed in claim 14, wherein the focal
length deriver further comprising: a calculator that calculates
the overall focal length of the image taking optical system by use
of a predetermined arithmetic expression from a coefficient and
the currently set focal length by the magnification varying optical
system of the lens unit when the lens unit is attached to the camera
body.
18. A digital camera as claimed in claim 17, wherein the calculator
receives a coefficient corresponding to the focal length currently
set by the magnification varying optical system of the lens unit
attached to the camera body, from either a storage provided in the
camera body or a storage provided in the lens unit.
19. A digital camera body as claimed in claim 17, wherein the calculator
calculates the overall focal length of the image taking optical
system in the lens unit attached to the camera body by use of the
predetermined arithmetic expression from the coefficient, the currently
set focal length by the magnification varying optical system, and
the driving amount of a focus adjustment optical system included
in the image taking optical system of the lens unit.
20. A digital camera as claimed in claim 19, wherein the camera
body further comprising: a second driver that drives the focus adjustment
optical system in a direction of an optical axis; a second driving
controller that controls an operation of the second driver; and
a driving amount outputter that outputs, to the focal length deriver,
information on a driving amount of the focus adjustment optical
system driven by the second driver under the control by the second
driving controller when the lens unit having the focus adjustment
optical system driven by the second driver and the second driving
controller is attached to the camera body.
Digital Camera Patent Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application
No. 2004-265890 filed in Japan on Sep. 13, 2004, the entire content
of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention belongs to the technical field of
single-lens reflex digital cameras, and more particularly, relates
to a blur compensation technology to compensate for a blur of a
captured image caused due to a camera shake.
[0004] 2. Description of the Related Art
[0005] An example of conventional interchangeable lenses attached
to single-lens reflex cameras is one in which a zoom lens for varying
the magnification is provided and the zoom lens is driven in the
direction of the optical axis by an operation of an operation ring
provided on the interchangeable lens. Moreover, an interchangeable
lens is known in which a focusing lens for performing focus adjustment
is provided and when the interchangeable lens is attached to the
camera body, the focusing lens is driven in the direction of the
optical axis by a driver in the camera body to which the interchangeable
lens is attached. Further, an interchangeable lens is known in which
the focusing lens and a driver that drives the focusing lens in
the direction of the optical axis are provided and a lens controller
that controls the driving of the driver when the interchangeable
lens is attached to the camera body is also provided.
[0006] On the other hand, among single-lens reflex cameras comprising
a camera body and an interchangeable lens structured so as to be
detachably attachable to the camera body, one has conventionally
been proposed in which the interchangeable lens is provided with
a function to perform blur compensation.
[0007] In interchangeable lenses having a magnification varying
function, even when the photographing magnification is the same,
the distance from the image capturing surface of the image sensor
to the rear principal point (hereinafter, referred to as focal length)
differs according to the kind of the zoom lens. Moreover, in interchangeable
lenses having a focus adjustment function in addition to the magnification
varying function, when the focusing lens is driven to perform focus
adjustment after the magnification of the zoom lens is set, the
determined focal length further changes according to the set photographing
magnification. Further, even in interchangeable lenses having a
fixed focal length lens, the focal length might be changed when
the focusing lens is driven to perform focus adjustment.
[0008] When it is considered to provide a single-lens reflex camera
with a blur compensation function, since the amount of compensation
for the blur differs according to the set focal length even when
the shake occurring on the camera is the same, in order to appropriately
perform blur compensation in the single-lens reflex camera, it is
necessary to derive the focal length according to the interchangeable
lens attached to the camera body and perform compensation according
to the focal length.
[0009] In that case, when the blur compensation function is provided
in each interchangeable lens as conventionally proposed, it is necessary
that each interchangeable lens be provided with a sensor that detects
the shake, a circuit that calculates the blur compensation amount
and the like, so that cost increases and the size of the interchangeable
lens increases.
SUMMARY OF THE INVENTION
[0010] A principal object of the present invention is to provide
a single-lens reflex digital camera capable of performing appropriate
blur compensation according to the interchangeable lens attached
to the camera body.
[0011] Another object of the present invention is to provide a
single-lens reflex digital camera capable of performing appropriate
blur compensation according to the interchangeable lens attached
to the camera body while preventing or suppressing cost increase
and size increase of the interchangeable lens.
[0012] The above-mentioned objects are attained by providing a
digital camera comprising a camera body, and a lens unit detachable
from said camera body and having an image taking optical system.
The camera body further comprising a communication portion configured
to receive an information on a focal length of the image taking
optical system from the lens unit; a shake detector that detects
a camera shake on the digital camera, and outputs a shake detection
signal; a blur compensator configured to receive a blur compensation
amount and compensates for a blur, due to the camera shake, of a
subject light image projected onto an image capturing surface of
an image sensor provided in the camera body, based on the received
blur compensation amount; a focal length deriver configured to obtain
an overall focal length of the image taking optical system, by use
of the information on the focal length obtained by the communication
portion; and a blur compensation controller configured to derive
the blur compensation amount for compensating for the blur based
on the overall focal length of the image taking optical system obtained
by the focal length deriver and the shake detection signal outputted
from the shake detector, and outputs the blur compensation amount
to the blur compensator.
[0013] These and other objects, advantages and features of the
invention will become apparent from the following description thereof
taken in conjunction with the accompanying drawings, which illustrate
specific embodiments of the invention.
BRIEF DESCRIPTION OF DRAWINGS
[0014] These and other objects, advantages and features of the
invention will become apparent from the following description thereof
taken in conjunction with the accompanying drawings in which:
[0015] FIG. 1 is a front view showing the structure of a digital
camera according to the present invention;
[0016] FIG. 2 is a rear view showing the structure of the digital
camera;
[0017] FIG. 3 is a view showing the internal structure of the digital
camera;
[0018] FIGS. 4(a) and 4(b) are schematic views showing the supporting
and driving structure of an image sensor;
[0019] FIGS. 5(a) and 5(b) are views showing the structure of an
X-axis actuator and a Y-axis actuator;
[0020] FIG. 6 is a view showing the structure when an in-unit AF
driving type lens unit is attached;
[0021] FIG. 7 is a block diagram showing the electric structure
of the digital camera 1 when the in-unit AF driving type lens unit
is attached to the camera body;
[0022] FIG. 8 is a view for explaining the calculation method of
a blur amount .DELTA.Z;
[0023] FIG. 9 is a view showing data transmitted from the lens
unit to a main controller of the camera body when each lens unit
is attached to the camera body;
[0024] FIG. 10 is a view showing the relationship between the coupler
rotation number and the focal length in a certain lens unit;
[0025] FIG. 11 is a view showing a table stored in a storage;
[0026] FIG. 12 is a view showing the detailed structure of mechanisms
(the image sensor, a blur compensation controller, an image sensor
driving mechanism) performing blur compensation;
[0027] FIG. 13 is a view showing the waveform of a driving pulse
applied to piezoelectric elements of the X-axis actuator and the
Y-axis actuator;
[0028] FIG. 14 is a flowchart showing the processing performed
according to the kind of the lens unit attached to the camera body;
and
[0029] FIG. 15 is a flowchart showing a series of image capturing
processings by the digital camera.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Hereinafter, an embodiment of the digital camera according
to the present invention will be described. FIG. 1 is a front view
showing the structure of the digital camera. FIG. 2 is a rear view
showing the structure of the digital camera. FIG. 3 is a view showing
the internal structure of the digital camera. In FIGS. 1 to 3, like
members are denoted by like reference numerals.
[0031] As shown in FIGS. 1 and 2, the digital camera 1 according
to the present embodiment is a single-lens reflex camera in which
a lens unit 2 is interchangeably attached to a box-shaped camera
body 1A. The digital camera 1 is provided with: the lens unit 2
attached substantially to the center of the front surface of the
camera body 1A; a first mode setting dial 3 disposed in an appropriate
position on the top surface; a shutter button 4 disposed on an upper
corner; an LCD (liquid crystal display) 5 disposed on the left side
of the rear surface; setting buttons 6 disposed below the LCD 5;
a jog dial 7 disposed on a side of the LCD 5; a push button 8 disposed
inside the jog dial 7; an optical viewfinder 9 disposed above the
LCD 5; a main switch 10 disposed on a side of the optical viewfinder
9; a second mode setting dial 11 disposed in the vicinity of the
main switch 10; a connection terminal 12 disposed above the optical
viewfinder 9; and an AF fill-in light emitter 13 disposed in an
appropriate position of the front surface.
[0032] The lens unit 2 comprises a plurality of lenses as optical
elements arranged in a direction vertical to the plane of the figure
within the lens barrel. As optical elements incorporated in the
lens unit 2, a zoom lens 53 performing magnification varying (see
FIG. 7) and a focusing lens 56 for performing focus adjustment (see
FIG. 7) are provided. By these lenses being driven in the direction
of the optical axis, magnification varying and focus adjustment
are performed.
[0033] The lens unit 2 of the present embodiment has, in an appropriate
position of the periphery of its lens barrel, an operation ring
that is rotatable along the periphery of the lens barrel. The zoom
lens 53 is a manual zoom lens that is moved in the direction of
the optical axis in accordance with the rotation direction and rotation
amount of the operation ring and is set at a zoom magnification
(photographing magnification) corresponding to the position to which
the zoon lens 53 is moved. The lens unit 2 can be detached from
the camera body 1A by depressing a detachment button 14 shown in
FIG. 1.
[0034] The first mode setting dial 3 is a substantially disk-shaped
member rotatable within a plane substantially parallel to the top
surface of the digital camera 1, and is provided for alternatively
selecting a mode or a function provided in the digital camera 1
such as a photographing mode to take a still image or a moving image
and a playback mode to play back a recorded image. Although not
shown, on the top surface of the first mode setting dial 3, characters
representative of the functions are printed at predetermined intervals
along the perimeter, and the function corresponding to the character
that is set at the position opposed to the index provided in an
appropriate position on the side of the camera body 1A is executed.
[0035] The shutter button 4 is a button depressed in two steps
of being half depressed and being fully depressed, and is provided
mainly for specifying the timing of the exposure control. By the
shutter button 4 being half depressed, the digital camera 1 is set
in an exposure standby state in which the setting of exposure control
values (the shutter speed and the aperture value) and the like is
performed, and by the shutter button 4 being fully depressed, the
optical image of the subject recorded into an image storage 85 described
later (see FIG. 7) is determined. The half depression of the shutter
button 4 is detected by a non-illustrated switch S1 being turned
on, and the full depression of the shutter button 4 is detected
by a non-illustrated switch S2 being turned on.
[0036] The LCD 5 which comprises a color liquid crystal panel performs
the display of an image captured by an image sensor 19 (see FIG.
3), the playback display of a recorded image and the like, and displays
the setting screens of the functions and modes provided in the digital
camera 1. An organic EL display or a plasma display may be used
instead of the LCD 5.
[0037] The setting buttons 6 (FIG. 2) are buttons for performing
operations associated with various functions provided in the digital
camera 1.
[0038] The jog dial 7 has an annular member having a plurality
of depression parts (the triangular parts in the figure) arranged
at predetermined intervals in the circumferential direction, and
is structured so that the depression of each depression part is
detected by a non-illustrated contact (switch) provided so as to
correspond to each depression part. The push button 8 is disposed
in the center of the jog dial 7. The jog dial 7 and the push button
8 are provided for inputting instructions as to the change of the
photographing magnification (the movement of the zoom lens in the
wide-angle direction or the telephoto direction), the frame advance
of the recorded image played back on the LCD 5, the setting of the
photographing conditions (the aperture value, the shutter speed,
the presence or absence of flash light emission, etc.), and the
like.
[0039] The optical viewfinder 9 optically displays the range in
which the subject is photographed.
[0040] The main switch 10 is a two-position slide switch that slides
horizontally. When the main switch 10 is set at the left position,
the power of the digital camera 1 is turned on, and when it is set
at the right position, the power is turned off.
[0041] The second mode setting dial 11 has a similar mechanical
structure to the first mode setting dial 3, and is provided for
performing operations associated with various functions provided
in the digital camera 1. The connection terminal 12 is a terminal
for connecting an external device such as a non-illustrated flash
device to the digital camera 1.
[0042] The AF fill-in light emitter 13 comprises a light emitting
device such as an LED, and outputs fill-in light when focus adjustment
is performed in a case where the brightness and contrast of the
subject are low.
[0043] The digital camera 1 has a shake detection sensor 47 in
an appropriate position of the camera body 1A. The shake detection
sensor 47 comprises, when a two-dimensional coordinate system with
the horizontal direction of FIG. 1 as the X-axis and the direction
vertical-to the X-axis as the Y-axis is assumed, an X sensor 47a
that detects a camera shake in the direction of the X-axis and a
Y sensor 47b that detects a camera shake in the direction of the
Y-axis. The X sensor 47a and the Y sensor 47b each comprise, for
example, a gyro using a piezoelectric element, and detect the angular
velocity of the shake in each direction.
[0044] As shown in FIG. 3, the following are provided in the camera
body 1A: an AF driving unit 15; the image sensor 19; a shutter unit
20; the optical viewfinder 9; a phase difference AF module 25; a
mirror box 26; and a main controller 28.
[0045] The AF driving unit 15 is provided with an AF actuator 16,
an encoder 17 and an output shaft 18. The AF actuator 16 includes
a motor generating a driving source such as a DC motor, a stepping
motor or an ultrasonic motor and a non-illustrated reduction system
for reducing the RPM of the motor.
[0046] Although not described in detail, the encoder 17 is provided
for detecting the rotation amount transmitted from the AF actuator
16 to the output shaft 18. The detected rotation amount is used
for calculating the position of an image capturing optical system
48 in the lens unit 2. The output shaft 18 is provided for transmitting
the driving force outputted from the AF actuator 16, to a lens driving
mechanism 50 in the lens unit 2.
[0047] The image sensor 19 is disposed substantially parallel to
the rear surface of the camera body 1A in a rear surface side area
of the camera body 1A. The image sensor 19 is, for example, a CCD
(charge coupled device) color area sensor of a Bayer arrangement
in which a plurality of photoelectric conversion elements each comprising
a photodiode or the like are two-dimensionally arranged in a matrix
and color filters of, for example, R (red), G (green) and B (blue)
having different spectral characteristics are disposed at a ratio
of 1:2:1 on the light receiving surfaces of the photoelectric conversion
elements. The image sensor 19 converts the light image of the subject
formed by the image capturing optical system 48 into analog electric
signals (image signals) of color components of R (red), G (green)
and B (blue), and outputs them as image signals of R, G and B. The
image sensor 19 may comprise a solid-state image sensor such as
a CMOS (complementary metal-oxide semiconductor).
[0048] FIGS. 4(a) and 4(b) are views showing the supporting and
driving structure of the image sensor 19. FIG. 4(a) is a view viewed
from the surface opposite to the image capturing surface of the
image sensor 19. FIG. 4(b) is a view taken on the arrow A-A of FIG.
4(a). As shown in FIG. 4(a), with respect to the image capturing
surface of the image sensor 19, a two-dimensional coordinate system
(corresponding to the two-dimensional coordinate system that is
set in FIG. 1) with the directions of the sides as the X-axis and
the Y-axis is set.
[0049] The supporting and driving structure of the image sensor
19 comprises a first to third substrates 29 to 31 having a substantially
rectangular shape, an X-axis actuator 33 and a Y-axis actuator 32.
The first substrate 29 is a hollow member fixed to the camera body
1A, and the X-axis actuator 33 is attached to an upper central position
of the first substrate 29. The second substrate 30 is a hollow member
coupled to the X-axis actuator 33. To the right side of the third
substrate 31, the Y-axis actuator 32 is attached, and to the plate
surface of the third substrate 31, the image sensor 19 is fixed.
The movements of the second substrate 30 and the third substrate
31 in the X-axis direction and in the Y-axis direction are guided
by non-illustrated rail members in predetermined positions.
[0050] FIGS. 5(a) and 5(b) are views showing the structure of the
X-axis actuator 33 and the Y-axis actuator 32. As shown in FIGS.
5(a) and 5(b), the X-axis actuator 33 and the Y-axis actuator 32
have a substantially similar structure, and comprise a piezoelectric
element 34, a driving shaft 35 bonded to one end of the piezoelectric
element 34, and a frictional coupling portion 36 frictionally coupled
to the driving shaft 35.
[0051] The piezoelectric element 34 comprises a plurality of piezoelectric
plates bonded together, and when a voltage is applied, expands or
contracts by an amount corresponding to the applied voltage. The
other end of the piezoelectric element 34 is bonded to a support
block 37 on the substrate 29 or 31. The driving shaft 35 is supported
by supports 38 and 39 on the substrate 29 or 31 so as to be movable
in the lamination direction of the piezoelectric plates constituting
the piezoelectric element 34, and when an expansion or contraction
displacement in the direction of the thickness occurs on the piezoelectric
element 34 bonded to the end of the driving shaft 35, the driving
shaft 35 moves in the axial direction.
[0052] The frictional coupling portion 36 has: a slider 40 through
which the driving shaft 35 passes and that is frictionally coupled
to the driving shaft 35 from below; a pad 41 that is inserted in
a notch 40a formed on the upper side of the slider 40 and is frictionally
coupled to the driving shaft 35 from above; and a plate spring 42
that adjusts the frictional coupling force between the driving shaft
35, and the slider 40 and the pad 41. A protrusion 41a formed on
the pad 41 abuts on the plate spring 42, and the frictional coupling
force can be adjusted by adjusting the clamping force of a screw
43 that fixes the plate spring 42 to the slider 40.
[0053] As shown in FIGS. 4(a) and 4(b), the second substrate 30
has a protrusion 30a protruding upward in the center of the upper
end, and the slider 40 is integrally formed on the first substrate
29 side surface of the protrusion 30a. By the frictional coupling
of the slider 40 and the driving shaft 35 of the X-axis actuator
33, the first substrate 29 and the second substrate 30 are coupled
together through the X-axis actuator 33, and the second substrate
30 is relatively movable in the direction of the X-axis with respect
to the first substrate 29.
[0054] Moreover, in the center of the first substrate 29 side surface
of the second substrate 30 on the right end, the slider 40 is integrally
formed, and by the frictional coupling of the slider 40 and the
driving shaft 35 of the Y-axis actuator 32, the third substrate
31 and the second substrate 30 are coupled together through the
Y-axis actuator 32, and the third substrate 31 is relatively movable
in the direction of the Y-axis with respect to the second substrate
30.
[0055] According to the above-described structure, a voltage corresponding
to the result of the detection by the shake detection sensor 47
is applied to the piezoelectric elements 34 of the X-axis actuator
33 and the Y-axis actuator 34, whereby the image sensor 19 of the
present embodiment is driven in the directions of the X- and Y-axes
by the Y-axis actuator 32 and the X-axis actuator 33 so that the
relative position of the subject light image with respect to the
image capturing surface of the image sensor 19 is maintained fixed
and the blur of the subject light image directed to the image capturing
surface of the image sensor 19 is optically corrected. The voltage
applied to the piezoelectric elements 34 will be described later.
[0056] Returning to FIG. 3, the shutter unit 20 comprises a focal
plane shutter (hereinafter, referred merely to shutter), and is
disposed between the rear surface of the mirror box 26 and the image
sensor 19.
[0057] The optical viewfinder 9 is disposed above the mirror box
26 disposed substantially in the center of the camera body 1A, and
comprises a focusing screen 21, a prism 22, an eyepiece lens 23
and a finder display element 24. The prism 22 is provided for horizontally
flipping the image on the focusing screen 21 and directing it to
the user's eye through the eyepiece lens 23 so that the subject
image can be viewed. The finder display element 24 displays the
shutter speed, the aperture value, the exposure compensation value
and the like in a lower part of a display screen formed within a
finder field frame 9a (see FIG. 2).
[0058] The phase difference AF module 25 is disposed below the
mirror box 26, and is provided for detecting the in-focus position
by a known phase difference detection method. The phase difference
AF module 25 has a structure disclosed, for example, in U.S. Pat.
No. 5,974,241 proposed by the applicant, and a detailed description
of the structure is omitted.
[0059] The mirror box 26 comprises a quick return mirror 45 and
a sub mirror 46. The quick return mirror 45 is structured so as
to be pivotable about a pivot axis 27 between a position inclined
substantially 45.degree. with respect to the optical axis L of the
image capturing optical system 48 as shown by the solid line of
FIG. 3 (hereinafter, referred to as inclined position) and a position
substantially parallel to the bottom surface of the camera body
1A as shown by the virtual line of FIG. 3 (hereinafter, referred
to as horizontal position).
[0060] The sub mirror 46 is disposed on the rear surface side of
the quick return mirror 45 (the side of the image sensor 19), and
is structured so as to be displaceable in conjunction with the quick
return mirror 45 between a position inclined substantially 90.degree.
with respect to the quick return mirror 45 in the inclined position
as shown by the solid line of FIG. 3 (hereinafter, referred to as
inclined position) and a position substantially parallel to the
quick return mirror 45 in the horizontal position as shown by the
virtual line of FIG. 3 (hereinafter, referred to as horizontal position).
The quick return mirror 45 and the sub mirror 46 are driven by a
mirror driving mechanism 59 described later (see FIG. 7).
[0061] When the quick return mirror 45 and the sub mirror 46 are
in the inclined position, the quick return mirror 45 reflects most
of the luminous flux by the image capturing optical system 48 toward
the focusing screen 21 and transmits the remaining luminous flux,
and the sub mirror 46 directs the luminous flux transmitted by the
quick return mirror 45 to the phase difference AF module 25.
[0062] At this time, the display of the subject image by the optical
viewfinder 9 and the focus adjustment according to the phase difference
detection method by the phase difference AF module 25 are performed,
whereas the display of the subject image by the LCD 5 is not performed
because no luminous flux is directed to the image sensor 19.
[0063] On the other hand, when the quick return mirror 45 and the
sub mirror 46 are in the horizontal position, since the quick return
mirror 45 and the sub mirror 46 are retracted from the optical axis
L, substantially all the luminous flux transmitted by the image
capturing optical system 48 is directed to the image sensor 19.
[0064] At this time, the display of the subject image by the LCD
5 is performed, whereas the display of the subject image by the
optical viewfinder 9 and the focus adjustment according to the phase
difference detection method by the phase difference AF module 25
are not performed.
[0065] The main controller 28 comprises, for example, a microcomputer
incorporating a storage such as a ROM storing a control program
and a flash memory temporarily storing data. A detailed function
thereof will be described later.
[0066] The shake detection sensor 47 corresponds to the shake detection
sensor 47 (the X sensor 47a and the Y sensor 47b) shown in FIG.
1. In FIG. 3, the X sensor 47a and the Y sensor 47b are collectively
shown as one sensor.
[0067] Next, the lens unit 2 attached to the camera body 1A will
be described.
[0068] In the present embodiment, to the camera body 1A, the following
two kinds of lens units can be attached: a lens unit that is subject
to the driving control of the focusing lens 56 (hereinafter, referred
to as AF control) from the camera body 1A; and a lens unit that
performs the driving control of the focusing lens 56 by a controller
(a lens driver 55 described later) within the lens unit without
subjected to the AF control from the camera body 1A.
[0069] Designating the former lens unit as body AF driving type
lens unit and the latter lens unit as in-unit AF driving type lens
unit, FIG. 3 is a view showing the structure when the body AF driving
type lens unit is attached to the camera body 1A. Moreover, the
structure when the in-unit AF driving type lens unit is attached
is shown in FIG. 6. These lens units are denoted by the same reference
numeral, and like members are denoted by like reference numerals.
[0070] As shown in FIG. 3, the body AF driving type lens unit 2
comprises the image capturing optical system 48, a lens barrel 49,
the lens driving mechanism 50, an encoder 51 and a storage 52.
[0071] In the image capturing optical system 48, the zoom lens
53 for changing the photographing magnification (focal length) (see
FIG. 7), the focusing lens unit 56 for adjusting the focus position
(see FIG. 7) and a diaphragm 54 for adjusting the quantity of light
incident on the image sensor 19 described later or the like provided
in the camera body 1A are held in the direction of the optical axis
L within the lens barrel 49. The image capturing optical system
48 captures the light image of the subject and forms the light image
on the image sensor 19 or the like. The change of the photographing
magnification (focal length) and the focus adjustment are performed
by the image capturing optical system 48 being driven in the direction
of the optical axis L by the AF actuator 16 within the camera body
1A.
[0072] The lens driving mechanism 50 comprises, for example, a
helicoid and a non-illustrated gear or the like that rotates the
helicoid, and integrally moves the image capturing optical system
48 in the direction of the arrow A parallel to the optical axis
L by receiving the driving force from the AF actuator 16 through
a coupler 44. The movement direction and the movement amount of
the image capturing optical system 48 are responsive to the rotation
direction and the number of rotations of the AF actuator 16, respectively.
[0073] The encoder 51 comprises: an encoding plate where a plurality
of code patterns are formed with predetermined pitches in the direction
of the optical axis L within the movement range of the image capturing
optical system 48; and an encoder brush that moves integrally with
the lens barrel 49 while sliding on the encoding plate, and is provided
for detecting the movement amount at the time of focus adjustment
of the image capturing optical system 48.
[0074] The storage 52 provides the main controller 28 in the camera
body 1A with the stored contents when the lens unit 2 is attached
to the camera body 1A and the main controller 28 in the camera body
1A makes a request for data. The storage 52 stores information on
the movement amount of the image capturing optical system 48 outputted
from the encoder 51, and stores lens codes for identifying the kind
of the lens unit or coefficients A0 to A2 for calculating the blur
compensation amount. Details thereof will be described later.
[0075] On the other hand, as shown in FIG. 6, the in-unit AF driving
type lens unit 2 comprises, like the body AF driving type lens unit,
the image capturing optical system 48, the lens barrel 49, the lens
driving mechanism 50 and the encoder 51, and comprises the lens
controller 55.
[0076] The lens controller 55 comprises, for example, a microcomputer
incorporating a storage (storage 55b described later) comprising
a ROM storing a control program or a flash memory temporarily storing
data. The lens controller 55 has a communication portion 55a performing
communication with the main controller 28 of the camera body 1A,
and although details will be described later, transmits data such
as the focal length of the zoom lens 53 to the main controller 28
and receives data such as the driving amount of the focusing lens
56 from the main controller 28.
[0077] Moreover, the lens controller 55 has the storage 55b for
storing data such as the focal length of the zoom lens 53 to be
transmitted from the communication portion 55a to the main controller
28 and data such as the driving amount of the focusing lens 56 transmitted
from the main controller 28 to the communication portion 55a. Further,
the lens controller 55 has, functionally, an AF driving controller
55c that controls the operation of the lens driving mechanism 50,
and when receiving data such as the driving amount of the focusing
lens 56 from the main controller 28, the AF driving controller 55c
controls the driving of the lens driving mechanism 50 based on the
data.
[0078] Next, the electric structure of the digital camera 1 according
to the present embodiment will be described. FIG. 7 is a block diagram
showing the overall electric structure of the digital camera 1 when
the in-unit AF driving type lens unit is attached to the camera
body 1A. The electric structure of the digital camera 1 when the
body AF driving lens unit is attached to the camera body 1A is different
from the block structure of the digital camera 1 shown in FIG. 7
in the electric structure within the lens unit 2. Since the difference
has already been described with reference to FIG. 6, a description
thereof is omitted. Moreover, the same members as those of FIGS.
1 to 6 are denoted by the same reference numerals.
[0079] As shown in FIG. 7, the image capturing optical system 48
corresponds to the image capturing optical system 48 shown in FIG.
6, and comprises the zoom lens 53 and the focusing lens 56. The
AF actuator 16, the output shaft 18, the lens driving mechanism
50 and the encoder 51 correspond to the AF actuator 16, the output
shaft 18, the lens driving mechanism 50 and the encoder 51 shown
in FIG. 6, respectively. The lens controller 55 corresponds to the
lens controller 55 shown in FIG. 6. The mirror unit 57 includes
the quick return mirror 45 and the sub mirror 46, and the phase
difference AF module 25 corresponds to the phase difference AF module
25 shown in FIG. 3. The shake detection sensor 47 corresponds to
the shake detection sensor 47 shown in FIGS. 1 and 3.
[0080] The image sensor 19 corresponds to the image sensor 19 shown
in FIG. 6, and the image capturing operations such as the start
and end of the exposure operation of the image sensor 19 and the
readout (horizontal synchronization, vertical synchronization, transfer)
of the output signal of each pixel at the image sensor 19 are controlled
by a timing control circuit 62 described later.
[0081] An image sensor driving mechanism 58 includes the X-axis
actuator 33 and the Y-axis actuator 32, and is controlled by the
main controller 28 (blur compensation controller 71 described later).
The mirror driving mechanism 59 drives the quick return mirror 45
and the sub mirror 46 between the inclined position and the horizontal
position, and is controlled by the main controller 28.
[0082] A signal processor 60 performs predetermined analog signal
processings on the analog image signals outputted from the image
sensor 19. The signal processor 60 has a CDS (correlated double
sampling) circuit and an AGC (automatic gain control) circuit, and
performs the noise reduction of the image signals by the CDS circuit
and performs the level adjustment of the image signals by the AGC
circuit.
[0083] An A/D converter 61 converts the analog image signals of
R, G and B outputted from the signal processor 60 into digital image
signals comprising a plurality of bits (for example, 10 bits) based
on a clock CLK2 outputted from the timing control circuit 62 described
later.
[0084] The timing control circuit 62 controls the operations of
the image sensor 19 and the A/D converter 61 by generating clocks
CLK1 and CLK2 based on a reference clock CLK0 outputted from the
main controller 28 described later and outputting the clock CLK1
to the image sensor 19 and the clock CLK2 to the A/D converter 61.
[0085] An image processor 63 is provided with: a black level correction
circuit 64 that corrects the black levels of the digital signals
of R, G and B A/D converted by the A/D converter 61 to a reference
black level; a white balance circuit (WB circuit) 65 that performs
the level conversion of the digital signals of the color components
of R (red), G (green) and B (blue) based on the reference of white
corresponding to the light source; and a gamma correction circuit
66 that corrects the gamma characteristics of the digital signals
of R (red), G (green) and B (blue).
[0086] An image memory 73 is a memory that, in the image capturing
mode, temporarily stores the image data outputted from the image
processor 63 and is used as the work area for performing a processing
described later on the image data by the main controller 28. In
the playback mode, the image memory 54 temporarily stores the image
data read out from the image storage 85 described later.
[0087] A VRAM 84 which has an image signal recording capacity corresponding
to the number of pixels of the LCD 5 is a buffer memory between
the main controller 28 and the LCD 5. The LCD 5 corresponds to the
LCD 5 of FIG. 2.
[0088] The image storage 85 comprises a memory card or a hard disk,
and stores the images generated by the main controller 28.
[0089] An input operation portion 67 includes the first mode setting
dial 3, the shutter button 4, the setting buttons 6, the jog dial
7, the push button 8, the main switch 10 and the second mode setting
dial 11, and is provided for inputting operation information to
the main controller 28.
[0090] Next, the main controller 28 will be described. In the following
description, the function in a case where the body AF driving type
lens unit is attached to the camera body 1A is described as well
as the function in a case where the in-unit AF driving type lens
unit is attached.
[0091] The main controller 28 controls the drivings of the members
in the digital camera 1 shown in FIG. 7 so as to be associated with
one another, and in the present embodiment, the main controller
28 has, functionally, an AF controller 68, a communication portion
69, a focal length calculator 70, the blur compensation controller
71 and a storage 72.
[0092] The AF controller 68 performs the focus adjustment processing
by the phase difference detection method by use of the output signal
of the phase difference AF module 25. When the in-unit AF driving
type lens unit 2 is attached to the camera body 1A, the AF controller
68 transmits the driving amount of the focusing lens 56 necessary
for obtaining in-focus state to the lens unit 2, and when the body
AF driving type lens unit 2 is attached, the AF controller 68 causes
the AF actuator 16 to drive the focusing lens 56 so as to be in
focus.
[0093] The communication portion 69 transmits and receives various
pieces of data to and from the lens unit 2 when the in-unit AF driving
type lens unit 2 or the body AF driving type lens unit 2 is attached
to the camera body 1A. An example of the data received from the
lens unit 2 is, in the present embodiment, data for performing blur
compensation, and as described later, the data for performing blur
compensation differs according to the kind of the lens unit.
[0094] A description necessary for explaining the data for performing
blur compensation will be given.
[0095] A case will be considered where a camera shake occurs in
a case where the light from a certain subject O is formed into an
image in a central position P of the image capturing surface of
the image sensor 19 when no shake is occurring on the digital camera
1 as shown in FIG. 8. In FIG. 8, the movements, in the direction
of the arrow Z, of various lenses in the lens unit 2 and the image
sensor 19 with respect to the subject O due to a camera shake are
represented as movements, in the direction of the arrow Z, of the
subject O with respect to the image sensor 19 and the like. Although
the blur amount with respect to the lens diameter is extremely small
in actuality, in FIG. 8, for the sake of the viewability of the
figure, the blur amount is shown as being large. Further, although
the lens unit 2 of the present embodiment comprises a plurality
of lens elements, in FIG. 8, these lens elements are shown as one
lens.
[0096] When the subject O relatively moves with respect to the
image sensor 19 and the like due to a camera shake, the image formation
point of the light from the subject O moves from the point P to
the point P'. At this time, when the distance from the point P to
the point P' is .DELTA.Z, the image captured by the image sensor
19 is blurred by .DELTA.Z due to the camera shake. Therefore, in
the present embodiment performing blur compensation by driving the
image sensor 19, in this case, the image sensor 19 is driven upward
by .DELTA.Z so that the image formation point of the light from
the subject O is held at the central point P of the image sensor
19.
[0097] When the distance from the rear principal point H to the
image formation point P of the image capturing optical system 48
in the lens unit 2 is r and the angle between the straight line
passing through the rear principal point H and the image formation
point P and the straight line passing through the rear principal
point H and the image formation point P' (hereinafter, referred
to as blur angle) is .PHI., from FIG. 8, the blur amount .DELTA.Z
can be expressed as.DELTA.Z=r tan .PHI. (1).
[0098] Since the blur angle .PHI. can be derived by the shake detection
sensor 47, it is understood that the blur amount .DELTA.Z can be
derived if the distance r from the rear principal point H to the
image formation point P can be obtained.
[0099] Although the lens unit 2 in the digital camera 1 of the
present embodiment is provided with the zoom lens 53 and has the
magnification varying function, when the kind of the zoom lens provided
in the lens unit 2 is different, the distance r from the rear principal
point H to the image formation point P is different even when the
photographing magnification is the same. Moreover, the lens unit
2 is provided with the focusing lens 56 and has the focus adjustment
function, and when the focusing lens 56 is driven to perform focus
adjustment after the magnification of the zoom lens 53 is set, the
focal length r determined by the set photographing magnification
further changes.
[0100] As described above, when the distance r from the rear principal
point H to the image formation point P is defined as the focal length
r, even when the shake occurring on the digital camera 1 is the
same, the compensation amount for the camera shake differs according
to the set focal length r.
[0101] Accordingly, in the present embodiment, blur compensation
is performed according to the kind of the lens unit 2. To perform
blur compensation according to the kind of the lens unit 2, the
main controller 28 obtains information on the focal length from
the lens unit 2 attached to the camera body 1A and derives the blur
amount to be compensated for.
[0102] (Description of the Kinds of Lens Units)
[0103] While it has been mentioned that examples of the lens unit
2 attachable to the camera body 1A of the digital camera 1 according
to the present embodiment include the in-unit AF driving type lens
unit and the body AF driving type lens unit, these lens units can
be further divided into one preregistered in the storage 72 of the
main controller 28 as a lens unit attachable to the camera body
1A and one not registered in the storage 72.
[0104] Hereinafter, of the in-unit AF driving type lens unit [A],
[A-1] one registered in the storage 72 will be referred to as in-unit
AF driving type old lens unit and [A-2] one not registered in the
storage 72 will be referred to as in-unit AF driving type new lens
unit, and of the body AF driving type lens unit [B], [B-1] one registered
in the storage 72 will be referred to as body AF driving type old
lens unit and [B-2] one not registered in the storage 72 will be
referred to as body AF driving type new lens unit.
[0105] FIG. 9 shows data transmitted from the lens unit 2 to the
main controller 28 of the camera body 1A when the above-mentioned
lens units 2 are attached to the camera body 1A. In FIG. 9, "old"
represents ones that are preregistered as lens units attachable
to the camera body 1A, and "new" represents ones that
are not registered.
[0106] Between the in-unit AF driving type lens unit and the body
AF driving type lens unit, since the principal component for the
driving control of the focusing lens 56 is different, the main component
for the storage of the data of the moving-out amount x of the focusing
lens 56 is also different. That is, in the in-unit AF driving type
lens unit, the lens controller 55 performs the driving control of
the focusing lens 56 and stores the data of the moving-out amount
x, whereas in the body AF driving type lens unit, the main controller
28 of the camera body 1A performs the driving control of the focusing
lens 56 and stores the moving-out amount x.
[0107] Therefore, because of this difference, when the in-unit
AF driving type lens unit is attached to the camera body 1A, the
moving-out amount x of the focusing lens 56 is transmitted from
the lens unit to the camera body 1A, whereas when the body AF driving
type lens unit is attached to the camera body 1A, no data communication
is performed between the lens unit and the camera body 1A (the communication
is unnecessary) The moving-out amount x of the focusing lens 56
is the moving-out amount x of the focusing lens 56 from the infinity
end (hereinafter, referred to merely as moving-out amount x) When
the main switch 10 is turned on, the focusing lens 56 is reset to
the infinity end.
[0108] Moreover, between the new lens unit and the old lens unit,
the presence or absence of the registration in the storage 72 of
the main controller 28 is different as mentioned above, and in the
old lens unit, a lens code representative of the kind of the lens
unit which lens code is registered in the storage 72 is transmitted
to the camera body 1A when the lens unit is attached to the camera
body 1A. On the other hand, when the new lens unit is attached to
the camera body 1A, the communication of the lens code is not performed
between the new lens unit and the camera body 1A, and instead of
the lens code, the communication of the coefficients A0 to A2 described
later is performed.
[0109] (Description of the Data Kinds of Each Lens Unit)
[0110] The data transmitted and received between the lens unit
2 and the camera body 1A will be described with respect to each
of the above-mentioned four kinds of lens units.
[0111] [A-1] As shown in FIG. 9, when the in-unit AF driving type
old lens unit is attached to the camera body 1A, the focal length
f at the current position of the zoom lens 53 when it is assumed
that the focusing lens 56 is absent, and the moving-out amount x
and the lens code of the focusing lens 56 are transmitted from the
lens unit to the camera body 1A.
[0112] [A-2] When the in-unit AF driving type new lens unit is
attached to the camera body 1A, the focal length f (hereinafter,
referred to merely as focal length f), the moving-out amount x of
the focusing lens 56 and the coefficients A0 to A2 are transmitted
from the lens unit and the camera body 1A. The coefficients A0 to
A2 are coefficients constituting an arithmetic expression (2), described
later, for calculating the blur compensation amount.
[0113] [B-1] When the body AF driving type old lens unit is attached
to the camera body 1A, the focal length f and the lens code are
transmitted from the lens unit to the camera body 1A.
[0114] [B-2] When the body AF driving type new lens unit is attached
to the camera body 1A, the focal length f and the coefficients A0
to A2 are transmitted from the lens unit to the camera body 1A.
[0115] The focal length calculator 70 calculates the overall focal
length r of the image capturing optical system 48 currently set
by use of the data transmitted from the lens unit 2 attached to
the camera body 1A. The calculation method of the focal length r
will be described with respect to each of the in-unit AF driving
type lens unit [A] and the body AF driving type lens unit [B]. For
convenience of explanation, the body AF driving type lens unit [B]
will be described first.
[0116] [B] When the lens unit attached to the camera body 1A is
the body AF driving type lens unit, the driving force outputted
from the AF actuator 16 is transmitted to the lens driving mechanism
50 in the lens unit 20 through the output shaft 18 and the coupler
44. At this time, the moving-out amount x of the focusing lens 56
and the coupler rotation number X are in a predetermined relationship
(for example, proportional relationship).
[0117] Moreover, the relationship between the coupler rotation
number X and the overall focal length r of the image capturing optical
system 48 differs among the lens units, and the relationship between
the coupler rotation number X and the focal length r in a certain
lens unit is shown in FIG. 10. In the present embodiment, in the
relationship between the coupler rotation number X and the focal
length r, the focal length r is expressed by being approximated
to the linear function of the coupler rotation number X as shown
by the following expression (2):r=f.times.(1+A0.times.2.sup.-7+A1.times.2.sup.-10.times.X+A2.times.2.-
sup.-14.times.X.sup.2) (2) Here, A0 to A2 are the coefficients.
[0118] [B-1] When the body AF driving type old lens unit is attached
to the camera body 1A, the focal length f in the expression (2)
and the lens code that is set according to the kind of the lens
unit are transmitted from the lens unit to the main controller 28
of the camera body 1A.
[0119] In the storage 72, a look-up table (LUT, hereinafter, referred
to merely as table) as shown in FIG. 11 is stored in association
with each lens code. That is, a table as shown in FIG. 11 is set
for each lens unit, and the table is stored in the storage 72. In
this table, the focal lengths f and the values of the coefficients
A0 to A2 are associated with each other.
[0120] The lens unit corresponding to the table shown in FIG. 11
is one provided with a zoom lens whose focal length f is adjustable
from 17 (mm) to 35 (mm). In a case where the lens unit is attached
to the camera body 1A, when the focal length f is set at 35 (mm)
with the operation ring, as the coefficient A0, "-5" is
transmitted from the lens unit to the main controller 28 of the
camera body 1A, as the coefficient A1, "29" is transmitted,
and as the coefficient A2, "-13" is transmitted.
[0121] The focal length calculator 70 substitutes the thus derived
coefficients A0 to A2, the focal length f in the expression (2)
received from the lens unit and the moving-out amount x of the focusing
lens 56 by the AF controller 68 (stored in the storage 72 in the
camera body 1A) into the expression (2) to calculate the currently
set overall focal length r of the image capturing optical system
48.
[0122] [B-2] When the body AF driving type new lens unit is attached
to the camera body 1A, since the focal length f in the expression
(2) and the coefficients A0 to A2 are transmitted from the lens
unit to the main controller 28 of the camera body 1A, the focal
length calculator 70 substitutes the focal length f, the coefficients
A0 to A2 and the moving-out amount x of the focusing lens 56 by
the AF controller 68 (stored in the storage 72 in the camera body
1A) into the expression (2) to calculate the currently set overall
focal length f of the image capturing optical system 48.
[0123] [A] On the other hand, when the lens unit attached to the
camera body 1A is the in-unit AF driving type lens unit, based on
the moving-out amount x of the focusing lens 56 transmitted from
the lens unit, the focal length calculator 70 calculates the coupler
rotation number X corresponding to the moving-out amount x by use
of a predetermined arithmetic expression.
[0124] [A-1] In a case where the in-unit AF driving type old lens
unit is attached to the camera body 1A, the focal length f in the
expression (2) and the lens code that is set according to the kind
of the lens unit together with the moving-out amount x of the focusing
lens 56 are transmitted from the lens unit to the main controller
28 of the camera body 1A. Since a table as shown in FIG. 11 is stored
in the storage 72 for each lens code, with reference to the table
corresponding to the lens code received from the lens unit, the
focal length calculator 70 derives the coefficients A0 to A2 corresponding
to the focal length f received from the lens unit, and then, substitutes
the coefficients A0 to A2, the focal length f and the calculated
coupler rotation number X into the expression (2) to calculate the
currently set overall focal length r of the image capturing optical
system 48.
[0125] [A-2] When the lens unit attached to the camera body 1A
is the in-unit AF driving type new lens unit, since the focal length
f in the expression (2) and the coefficients A0 to A2 together with
the moving-out amount x of the focusing lens 56 are transmitted
from the lens unit to the main controller 28 of the camera body
1A, the focal length calculator 70 substitutes the focal length
f, the coefficients A0 to A2 and the calculated coupler rotation
number X into the expression (2) to calculate the currently set
overall focal length r of the image capturing optical system 48.
[0126] (Description of the Blur Compensation Operation)
[0127] The blur compensation controller 71 substitutes the actual
focal length r calculated by the focal length calculator 70 and
the angular velocity (corresponding to the angle .PHI.) obtained
from the detection signal of the shake detection sensor 47 into
the expression (1) to calculate the driving amount .DELTA.Z (hereinafter,
referred to as blur compensation amount .DELTA.Z) of the image sensor
19 that can compensate for (cancel out) the blur, and controls the
operation of the image sensor driving mechanism 58 based on the
blur compensation amount .DELTA.Z. When the blur compensation amount
.DELTA.Z is a negative value, since this means that the image sensor
10 is driven in a direction opposite to the direction of the case
of a positive value, the blur compensation amount .DELTA.Z includes
the blue compensation direction.
[0128] FIG. 12 is a view showing the detailed structure of the
mechanism (the image sensor 19, the blur compensation controller
71, the image sensor driving mechanism 58) performing blur compensation
according to the present embodiment.
[0129] As shown in FIG. 12, the shake detection sensor 47 detects
a shake .omega., and outputs it to a high pass filter (HPF) 74 as
an angular velocity signal. The high pass filter 74 removes the
DC drift and offset contained in the angular velocity signal from
the shake detection sensor 47. An integrator 75 integrates the angular
velocity signal having passed through the high pass filter 74 into
an angle signal. A level setter 76 adjusts the level of the angle
signal to convert the angle signal into a compensation position
control signal in order to determine the movement amount of the
image sensor 19 or the position (compensation position) to which
the image sensor 19 is to be moved. The level by the level setter
76 is predetermined according to the focal length of the lens, and
inputted from the main controller 28 to the level setter 76. The
position of the image sensor 19 is detected by a position sensor
80. A driving signal outputter 78 generates and outputs a signal
for driving elements 79 (the piezoelectric elements 34 of the X-axis
actuator 33 and the Y-axis actuator 32).
[0130] A PID portion 77, the driving signal outputter 78, the driving
elements 79, the image sensor 19, the position sensor 80 and a subtractor
81 constitute a feedback loop. The subtractor 81 subtracts the compensation
position detection signal of the position sensor 80 from the compensation
position control signal of the level setter 76. The PID portion
77 performs proportional compensation (P compensation), integral
compensation (I compensation) and differential compensation (D compensation)
on the output signal from the subtractor 81, and compensates for
the delay transmission characteristic from the driving elements
79 to the image sensor 19.
[0131] Next, the operations of the driving signal outputter 78
and the driving elements 79 will be described. When the driving
of the image sensor 19 in the direction of the X-axis is determined,
as shown in FIG. 13, a driving pulse of a waveform comprising gently
rising parts 82 and succeeding rapidly falling parts 83 is applied
to the piezoelectric element 34 of the X-axis actuator 33. In the
gently rising parts 82 of the driving pulse, the piezoelectric element
34 gently expands in the direction of the thickness, and the driving
shaft 35 displaces in the direction shown by the arrow a (see FIGS.
5(a), 5(b) and 6). Consequently, the substrate 30 frictionally coupled
to the driving shaft 35 by the frictional coupling portion 36 also
moves in the direction of the arrow a.
[0132] In the rapidly falling parts 83 of the driving pulse, the
piezoelectric element 34 rapidly contracts in the direction of the
thickness, and the driving shaft 35 displaces in a direction opposite
to the arrow a. At this time, the substrate 30 frictionally coupled
to the driving shaft 35 by the frictional coupling portion 36 substantially
remains in the position against the frictional coupling force between
the driving shaft 35 and the frictional coupling portion 36 because
of its inertial force, and does not move. The word substantially
referred to here means that one is included that follows while sliding
between the frictional coupling portion 36 and the driving shaft
35 fixed to the substrate 30 in the direction of the arrow a and
the opposite direction and moves in the direction of the arrow a
as a whole because of the difference in driving time. The movement
configuration is determined according to the friction condition
being provided.
[0133] By continuously applying the driving pulse of the above-described
waveform to the piezoelectric element 34, the image sensor 19 can
be continuously moved in the positive direction of the X-axis.
[0134] The movement of the image sensor 19 in the negative direction
of the X-axis, that is, in the direction opposite to the arrow a
can be achieved by applying a driving pulse of a waveform comprising
rapidly rising parts 82 and succeeding gently falling parts 83 to
the piezoelectric element 34. When the image sensor 19 is moved
to a predetermined position, the supply of the driving pulse is
stopped, so that the movement of the image sensor 19 is stopped.
[0135] The driving of the image sensor 19 in the direction of the
Y-axis is substantially similar to the driving of the image sensor
19 in the direction of the X-axis.
[0136] Returning to FIG. 7, with respect to the in-unit AF driving
type old lens unit and the body AF driving type old lens unit, the
storage 72 stores the correspondence between the lens code and the
table that are set for each lens unit and stores, in a table format,
the relationship between the focal length f of the lens unit and
the coefficients A0, A1 and A2 as shown in FIG. 11.
[0137] Next, the blur compensation processing by the digital camera
1 according to the present invention will be described. FIG. 14
is a flowchart showing the processing performed according to the
kind of the lens unit attached to the camera body 1A.
[0138] As shown in FIG. 14, in a case where the lens unit 2 is
attached to the camera body 1A (YES at step #1), when the attached
lens unit 2 is the body AF driving type new lens unit (YES at step
#2), the main controller 28 captures the focal length f and the
coefficients A0 to A2 from the lens unit 2 (step #3), and calculates
the blur compensation amount .DELTA.Z by use of these pieces of
data and the coupler rotation number x corresponding to the driving
amount of the focusing lens 56 by the control by the AF controller
68 (step #4).
[0139] When the attached lens unit 2 is the body AF driving type
old lens unit (NO at step #2, YES at step #5), the main controller
28 captures the focal length f and the lens code from the lens unit
2 (step #6), and calculates the blur compensation amount .DELTA.Z
by use of these pieces of data and the coupler rotation number X
corresponding to the driving amount of the focusing lens 56 by the
control by the AF controller 68 (step #7). In this case, the coefficients
A0 to A2 are derived from the lens code and the focal length f by
use of the table stored in the storage 72.
[0140] In the case of the in-unit AF driving type old lens unit
(NO at steps #2 and #5, YES at step #8), the main controller 28
captures the focal length f, the moving-out amount x of the focusing
lens 56 and the lens code from the lens unit (step #9), and calculates
the blur compensation amount .DELTA.Z by use of these pieces of
data (step #10). In this case, the moving-out amount x of the focusing
lens 56 is converted into the coupler rotation number by a predetermined
arithmetic expression, and the coefficients A0 to A2 are derived
from the lens code and the focal length f by use of the table stored
in the storage 72.
[0141] In the case of the in-unit AF driving type new lens unit
(NO at steps #2, #5, #8), the main controller 28 captures the focal
length f, the moving-out amount x of the focusing lens 56 and the
coefficients A0 to A2 from the lens unit 2 (step #11), and calculates
the blur compensation amount .DELTA.Z by use of these pieces of
data (step #12). In this case, the moving-out amount x of the focusing
lens 56 is converted into the coupler rotation number by a predetermined
arithmetic expression.
[0142] A series of image capturing processings by the digital camera
1 according to the present embodiment will be described. FIG. 15
is a flowchart showing the image capturing processings. In this
example, the lens unit 2 is already attached to the camera body
1A.
[0143] As shown in FIG. 15, the main controller 28 determines whether
the half depression (S1: ON) of the shutter button 4 is performed
or not (step #21), and when the half depression is not performed,
the main controller 28 waits until the half depression is performed
(NO at step #21). When the half depression of the shutter button
4 is performed (YES at step #21), the main controller 28 starts
the power supply to the shake detection sensor 47 (step #22), and
communicates data such as the focal length f corresponding to the
lens unit with the lens unit (step #23).
[0144] The main controller 28 calculates the blur compensation
amount .DELTA.Z by use of the data received from the lens unit 2
(step #24). The calculation of the blur compensation amount .DELTA.Z
is performed in order that the blur compensation operation (the
driving operation of the image sensor 19) can be rapidly performed
when the full depression of the shutter button 4 is performed. While
the blur compensation operation (the driving operation of the image
sensor 19) may be started at this point of time, for the reduction
in power consumption and the prevention of breakage of the X-axis
actuator 33 and the Y-axis actuator 32, the processings are performed
only up to the calculation of the blur compensation amount .DELTA.Z.
[0145] The main controller 28 determines the exposure control values
(the shutter speed and the aperture value) based on the brightness
of the subject (step #25), and starts the AF processing by the phase
difference detection method (step #26).
[0146] The main controller 28 (the AF controller 68) determines
whether in-focus state is obtained or not (step #27) When in-focus
state is not obtained (NO at step #27), the main controller 28 drives
the focusing lens 56 based on the driving direction and the driving
amount determined by the focus adjustment processing (AF processing)
performed at step S26 (step #28), and then, returns to the processing
of step #21 and repeats the processing from steps #21 to #26.
[0147] When in-focus state is obtained (YES at step #27), the main
controller 28 determines the operation condition of the shutter
button 4. That is, the main controller 28 determines whether the
half depression of the shutter button 4 is canceled or not (step
#29). When the half depression is canceled (YES at step #29), the
main controller 28 returns to the processing of step #21, and when
the half depression is not canceled (NO at step S29), the main controller
28 determines whether the full depression (S2: ON) of the shutter
button 4 is performed or not (YES at step #30). When the full depression
of the shutter button 4 is not performed (NO at step #30), the main
controller 28 returns to the processing of step #29.
[0148] When the full depression of the shutter button 4 is performed
(YES of step #30), the main controller 28 causes the mirror driving
mechanism 59 to perform driving so that the quick return mirror
45 and the sub mirror 46 are brought into the horizontal position
(mirror up) (step #31), and the blur compensation controller 71
performs the calculation of the blur compensation amount .DELTA.Z
and the driving control of the image sensor 19 in order to perform
the blur compensation operation (step #32).
[0149] Then, the main controller 28 opens the shutter unit 20 (step
#33), and causes the image sensor 19 to perform the image capturing
operation (exposure operation) with the exposure control values
set at step #25 with the focusing lens 56 being situated in the
position set at step #27 (step #34).
[0150] Then, the main controller 28 closes the shutter unit 20
(step #35), stops the calculation of the blur compensation amount
.DELTA.Z and the driving control of the image sensor 19 (step #36),
and returns the image sensor 19 to the original position (initial
position) (step #37). The original position is, for example, a position
where the center of the image sensor 19 passes through the optical
axis of the image capturing optical system 48.
[0151] The main controller 28 performs image processings such as
compression processing on the image obtained by the image capturing
operation of the image sensor 19 (step #38), and stores the image
having undergone the image processings into the image storage 85
(step #39). Moreover, in parallel with the processings of steps
#35 to #39, the main controller 28 causes the mirror driving mechanism
59 so that the quick return mirror 45 and the sub mirror 46 are
brought into the inclined position (mirror down). Although the digital
camera according to the present embodiment is a single-lens reflex
camera in which a lens unit having a zoom lens is interchangeably
attached to a camera body, a single-lens reflex camera in which
a lens unit having a fixed focal length lens is interchangeably
attached to a camera body may be employed.
[0152] As described above, in the digital camera 1 of the present
embodiment, when the lens unit 2 is attached to the camera body
1A, the main controller 28 of the camera body 1A obtains the data
necessary for calculating the currently set overall focal length
r of the image capturing optical system 48 from the lens unit 2,
calculates the focal length r by use of this data, and obtains the
blur compensation amount .DELTA.Z based on the expression (1) from
the focal length r and the blur amount obtained by the detection
signal of the shake detection sensor 47, so that blur compensation
can be reliably performed irrespective of which of the four kinds
of lens units 2 is attached to the camera body 1A.
[0153] Moreover, since a structure driving the image sensor 19
in two orthogonal axial directions on the image capturing surface
is adopted as the structure performing blur compensation, compared
to a structure having an optical system for blur compensation for
each lens unit and performing blur compensation by use of the optical
system, cost increase and size increase of the lens unit 2 can be
prevented or suppressed.
[0154] According to the present invention, compared to a case where
an optical system for blur compensation and a driver for driving
it are provided in the lens unit, it is unnecessary to perform the
communication processing to transmit and receive the information
on the blur compensation amount and the blur compensation direction
obtained by the blur compensation controller between the camera
body and the lens unit and the period of the blur compensation operation
can be reduced accordingly, so that more accurate blur compensation
can be performed.
[0155] Further, according to the present invention, appropriate
blur compensation can be performed according to the lens unit attached
to the camera body. Moreover, since at least the focal length deriver
and the blur compensation controller are provided in the camera
body, compared to a case where these are provided for each of different
kinds of lens units, cost increase and size increase of the lens
unit can be prevented or suppressed. When the shake detector is
provided in the camera body, cost increase of the lens unit and
size increase of the interchangeable lens can be further prevented
or suppressed.
[0156] In the present invention, the modifications described in
the following modes (1) and (2) are adoptable in addition to the
above-described embodiment or instead of the above-described embodiment:
[0157] (1) The present invention is applicable even when the means
for compensating for a blur is an optical element that optically
compensates for a blur (for example, a blur compensation lens).
[0158] (2) The sensor that performs the detection of a camera shake
amount in the present embodiment is not limited to an angular velocity
sensor as described above but may be an acceleration sensor.
[0159] (3) While in the above-described embodiment, the blur compensation
operation is always performed when the main power of the digital
camera 1 is on, the present invention is not limited thereto. Since
there can be cases where photographing is performed with a blur
being caused, the blur compensation operation as described above
may be performed in a case where a button for alternatively selecting
a blur compensation mode to perform blur compensation by the image
sensor driving mechanism 58 and the image sensor 19 described later
and a non-blur compensation mode not to perform blur compensation
is provided and the blur compensation mode is set by the button.
[0160] Although the present invention has been fully described
by way of examples with reference to the accompanying drawings,
it is to be noted here that various changes and modifications will
be apparent to those skilled in the art. Therefore, unless otherwise
such changes and modifications depart from the scope of the present
invention, they should be construed as being included therein.
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