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Digital Camera Patent Abstract
A single-lens-reflex digital camera in which an optical image of
an object that is to be photographed via a photographing lens is
reflected by a main mirror to be formed on a focusing screen so
that the optical image is viewed through a viewfinder while the
main mirror is retracted from an optical path of the photographing
lens to capture an image of the object by an image pickup device,
the single-lens-reflex digital camera includes an electroluminescent
display provided on the focusing screen, wherein the electroluminescent
display displays at least the object image captured by the image
pickup device. The single-lens-reflex digital camera is configured
to allow the object image displayed by the electroluminescent display
and the optical image formed on the focusing screen to be viewed
through the viewfinder.
Digital Camera Patent Claims
1. A single-lens-reflex digital camera in which an optical image
of an object that is to be photographed via a photographing lens
is reflected by a main mirror to be formed on a focusing screen
so that said optical image is viewed through a viewfinder while
said main mirror is retracted from an optical path of said photographing
lens to capture an image of said object by an image pickup device,
wherein said single-lens-reflex digital camera comprises: an electroluminescent
display provided on said focusing screen, wherein said electroluminescent
display displays at least said object image captured by said image
pickup device, and wherein said single-lens-reflex digital camera
is configured to allow said object image displayed by said electroluminescent
display and said optical image formed on said focusing screen to
be viewed through said viewfinder.
2. The single-lens-reflex digital camera according to claim 1,
wherein said electroluminescent display is formed integrally with
said focusing screen.
3. The single-lens-reflex digital camera according to claim 2,
wherein said electroluminescent display displays said object image
captured by said image pickup device and various information, when
said main mirror is retracted from said optical path of said photographing
lens, and wherein said electroluminescent display only displays
said various information when said main mirror lies on said optical
path of said photographing lens.
4. The single-lens-reflex digital camera according to claim 2,
further comprising a light shield screen which selectively covers
and uncovers a surface of said focusing screen which is adjacent
to said main mirror.
5. The single-lens-reflex digital camera according to claim 4,
further comprising a mirror drive mechanism which drives said main
mirror, and a light shield screen drive mechanism which retracts
said light shield screen from a position thereof which covers said
surface of said focusing screen, wherein said mirror drive mechanism
and said light shield screen drive mechanism are integrated with
each other.
6. The single-lens-reflex digital camera according to claim 3,
wherein said main mirror is retracted from said optical path of
said photographing lens in the case where said photographing lens
has an image stabilizing capability.
7. The single-lens-reflex digital camera according to claim 1,
wherein said single-lens-reflex digital camera is configured to
allow said object image displayed by said electroluminescent display
and said optical image formed on said focusing screen to be selectively
viewed through said viewfinder.
8. The single-lens-reflex digital camera according to claim 1,
wherein said electroluminescent display is positioned on one side
of said focusing screen from said main mirror.
9. The single-lens-reflex digital camera according to claim 2,
further comprising a light shield screen which is selectively inserted
into and retracted from a space between said focusing screen and
said main mirror when said main mirror is in a retracted position
in which said main mirror is positioned out of said optical path
of said photographing lens.
10. A single-lens-reflex digital camera comprising: a quick-return
mirror; a focusing screen, positioned above said quick-return mirror,
wherein light of an object which is passed through a photographing
optical system and reflected by said quick-return mirror to be formed
as an optical image on said focusing screen is viewed through a
viewfinder optical system, and wherein, upon a shutter release,
said quick-return mirror is retracted from an optical path of said
photographing lens to allow said object light that is passed through
said photographing optical system to be incident on an image pickup
device so that said image pickup device picks up a digital image
of said object; and an electroluminescent display which displays
said digital image on said focusing screen at least when said quick-return
mirror is retracted from said optical path.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a single-lens-reflex digital
camera, more specifically to a single-lens-reflex digital camera
which is designed and configured to allow the photographer to see
an optical image and a live digital image of an object to be photographed,
so as to be selectively viewed through a viewfinder.
[0003] 2. Description of the Prior Art
[0004] Typical SLR (single-lens-reflex) digital cameras are provided
with a main mirror (quick-return mirror) positioned on an optical
axis of a photographing lens so that light of an object which is
passed through the photographing lens is reflected by the main mirror
to be formed on a focusing screen as an optical image of the object.
This optical image formed on the focusing screen is viewed through
a viewfinder (viewfinder optical system). When the main mirror has
been retracted from an optical path of the photographing lens, i.e.,
when the main mirror has risen, the light of an object which is
passed through the photographing lens is formed on an image pickup
device while an image signal of the object is visually indicated
on an external LCD (liquid crystal display) monitor, or the like,
to be viewed as a live digital image. Accordingly, in this type
of digital camera, if the photographer desires to continue observing
an object to be photographed through the digital camera, they have
only two ways of viewing: they observe either an optical image of
the object through the viewfinder or a live digital image of the
object which is displayed on the external LCD monitor when the main
mirror rises.
[0005] In view of this type of digital camera, a technology that
installs a small LCD monitor in a viewfinder optical system to enable
the photographer to observe a live digital image of an object, which
is taken by an image pickup device and displayed on an external
LCD monitor, through the viewfinder has been proposed in Japanese
unexamined patent publication H10-294888 (hereinafter referred to
as a first publication). According to this technology, the photographer
can selectively observe the optical image and the live digital image
through the viewfinder, which is effective for enhancing the convenience
of the digital camera at a time of exposure.
[0006] In SLR digital cameras, to enable the photographer to view
an optical image of an object and various information (e.g., an
f-number and a shutter speed) at the same time, the viewfinder is
provided therein with a display device for making the various information
display on the focusing screen as visual information. An LCD is
used as such a display device. Visual information displayed on the
LCD is formed either on the focusing screen or at a position on
an optical axis which is optically equivalent to the position of
the focusing screen by an optical device. In Japanese unexamined
patent publication 2000-137268 (hereinafter referred to as a second
publication), a device for displaying a required image on the focusing
screen using an EL (electroluminescent) display instead of such
a type of LCD has been proposed. Specifically, forming an EL display
in a peripheral part of the object image forming area (picture area)
of the focusing screen and making the EL display indicate various
information by making an EL drive circuit drive the EL display makes
it possible to display the various information on the focusing screen
together with an optical image of an object so that the photographer
can view the various information and the optical image of the object
at the same time through the viewfinder. Additionally, in the second
publication, an arrangement wherein an EL display is formed on a
surface of a prism serving as an element of a viewfinder optical
system has also been proposed.
[0007] In the first publication, to allow the photographer to selectively
view an optical image and a live digital image of an object, a movable
mirror or the like which is installed in a part of a viewfinder
optical system is driven to switch between two optical paths, and
accordingly, the digital camera has to be provided with a drive
mechanism for switching between the two optical paths, which complicates
the structure of the viewfinder. Additionally, there is a problem
of the viewfinder becoming large because an LCD monitor (internal
LCD monitor) is installed in the viewfinder. Additionally, in the
second publication, although the EL display mounted to the focusing
screen can be made thinner than an LCD, this EL display displays
only visual information, and accordingly, an image to be displayed
on the focusing screen is limited solely to an optical image which
is formed on the focusing screen via a photographing lens. On this
account, to visually check the live digital image, the photographer
has no other choice but to visually check the live digital image
displayed on the external LCD monitor installed in the viewfinder,
so that the viewfinder only has a capability similar to the viewfinder
of a conventional SLR camera in the second publication.
SUMMARY OF THE INVENTION
[0008] The present invention provides an SLR camera which is designed
and configured to allow a live digital image to be viewed through
a viewfinder without employing a complicated structure and without
requiring a complicated control for switching between an optical
image and a live digital image.
[0009] According to an aspect of the present invention, a single-lens-reflex
digital camera is provided, in which an optical image of an object
that is to be photographed via a photographing lens is reflected
by a main mirror to be formed on a focusing screen so that the optical
image is viewed through a viewfinder while the main mirror is retracted
from an optical path of the photographing lens to capture an image
of the object by an image pickup device. The single-lens-reflex
digital camera includes an electroluminescent display provided on
the focusing screen, wherein the electroluminescent display displays
at least the object image captured by the image pickup device, and
the single-lens-reflex digital camera is configured to allow the
object image displayed by the electroluminescent display and the
optical image formed on the focusing screen to be viewed through
the viewfinder.
[0010] It is desirable for the electroluminescent display to be
formed integrally with the focusing screen.
[0011] It is desirable for the electroluminescent display to display
the object image captured by the image pickup device and various
information, when the main mirror is retracted from the optical
path of the photographing lens, and for the electroluminescent display
to only display the various information when the main mirror lies
on the optical path of the photographing lens.
[0012] It is desirable for the single-lens-reflex digital camera
to include a light shield screen which selectively covers and uncovers
a surface of the focusing screen which is adjacent to the main mirror.
[0013] It is desirable for the single-lens-reflex digital camera
to include a mirror drive mechanism which drives the main mirror,
and a light shield screen drive mechanism which retracts the light
shield screen from a position thereof which covers the surface of
the focusing screen. The mirror drive mechanism and the light shield
screen drive mechanism are integrated with each other.
[0014] It is desirable for the main mirror to be retracted from
the optical path of the photographing lens in the case where the
photographing lens has an image stabilizing capability.
[0015] It is desirable for the single-lens-reflex digital camera
to be configured to allow the object image displayed by the electroluminescent
display and the optical image formed on the focusing screen to be
selectively viewed through the viewfinder.
[0016] It is desirable for the electroluminescent display to be
positioned on one side of the focusing screen from the main mirror.
[0017] It is desirable for the single-lens-reflex digital camera
to include a light shield screen which is selectively inserted into
and retracted from a space between the focusing screen and the main
mirror when the main mirror is in a retracted position in which
the main mirror is positioned out of the optical path of the photographing
lens.
[0018] In an embodiment, a single-lens-reflex digital camera is
provided, including a quick-return mirror; a focusing screen, positioned
above the quick-return mirror, wherein light of an object which
is passed through a photographing optical system and reflected by
the quick-return mirror to be formed as an optical image on the
focusing screen is viewed through a viewfinder optical system, and
wherein, upon a shutter release, the quick-return mirror is retracted
from an optical path of the photographing lens to allow the object
light that is passed through the photographing optical system to
be incident on an image pickup device so that the image pickup device
picks up a digital image of the object; and an electroluminescent
display which displays the digital image on the focusing screen
at least when the quick-return mirror is retracted from the optical
path.
[0019] According to the present invention, since the focusing screen
is provided with an EL display that can be formed thin, and since
an object image picked up by an image pickup device is also displayed
on the focusing screen by the EL display, an optical image of an
object formed on the focusing screen and a live digital image of
the same object displayed by the EL display can be selectively viewed
through the viewfinder. According to this structure, the photographer
can take a picture of an object while viewing a live digital image
of the object through the viewfinder in an SLR digital camera while
the viewfinder does not have to be provided with any switching mechanism
such as that taught in the first publication for switching between
the optical image and the live digital image, which facilitates
the image switching operation and prevents the structure of the
camera from becoming complicated.
[0020] Moreover, the digital image displayed by the EL display
does not become difficult to view due to reflections of the main
mirror due to placing a light shielding screen below the focusing
screen. Furthermore, in the case where the photographing lens is
a type which incorporates an image-stabilizing optical element such
as an image-stabilizing lens element, the photographer can be prevented
from getting finder-view motion sickness by viewing a live digital
image displayed by the EL display.
[0021] The present disclosure relates to subject matter contained
in Japanese Patent Application No. 2005-214993 (filed on Jul. 25,
2005) which is expressly incorporated herein in its entirety.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be discussed below in detail
with reference to the accompanying drawings, in which:
[0023] FIG. 1 is a front perspective view of an SLR digital camera
according to the present invention;
[0024] FIG. 2 is a rear perspective view of the SLR digital camera
shown in FIG. 1;
[0025] FIG. 3 is a front perspective view of a mirror box and associated
components mounted to the mirror box in the camera body shown in
FIGS. 1 and 2;
[0026] FIG. 4 is an exploded perspective view of the mirror box
and the associated components that are shown in FIG. 3;
[0027] FIG. 5 is a perspective view of elements of a mirror drive
mechanism and a light shielding screen drive mechanism that are
provided in the camera body shown in FIGS. 1 and 2;
[0028] FIG. 6 is a side elevational view of the elements of the
mechanisms shown in FIG. 5, viewed from the left side in FIG. 5;
[0029] FIGS. 7A and 7B are perspective views of two gears GJ and
GK shown in FIGS. 5 and 6 in different states;
[0030] FIG. 8 is a perspective view of the elements of the mirror
drive mechanism and the light shielding screen drive mechanism that
are shown in FIG. 5 in a different state, illustrating operations
of these two mechanisms;
[0031] FIG. 9 is a side elevational view of the elements of the
mechanism shown in FIG. 8, viewed from the left side in FIG. 8;
[0032] FIG. 10 is a perspective external view of the focusing screen
shown in FIGS. 5, 6, 8 and 9;
[0033] FIG. 11A is a cross sectional view of the focusing screen
shown in FIG. 10;
[0034] FIG. 11B is an enlarged cross sectional view of a portion
of the focusing screen shown in FIG. 11A;
[0035] FIG. 12 is an enlarged cross sectional view of an electroluminescent
portion of the focusing screen shown in FIGS. 10, 11A and 11B;
[0036] FIG. 13 is a block diagram of components of the SLR digital
camera shown in FIGS. 1 and 2, showing the overall structure thereof;
[0037] FIGS. 14A and 15B show a flow chart showing operations of
a photographing process performed in the SLR digital camera shown
in FIGS. 1 and 2; and
[0038] FIGS. 15A and 15B show a flow chart showing operations of
an EL display indicating process performed in the SLR digital camera
shown in FIGS. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] The embodiment of the SLR digital camera shown in FIGS.
1 and 2 is provided with a camera body 1 and an interchangeable
photographing lens 2 (see FIG. 13) detachably attached to the camera
body 1. The photographing lens 2 is not shown in FIGS. 1 and 2.
The camera body 1 is provided on the front thereof with a lens mount
(mount ring) 3 to which the photographing lens 2 is detachably attached,
and is further provided on the top of the camera body 1 with a main
switch 4, a shutter release button 5, a front select dial 6, a mode
select dial 7, an information-indicating LCD panel 8 and an accessory
shoe (hot shoe) 9. The camera body 1 is provided on the back thereof
with a viewfinder window 10, an external LCD monitor 11, an EL display
ON/OFF button 12 and a rear select dial 13.
[0040] FIG. 3 is a front perspective view of a mirror box 20 and
associated components mounted to the mirror box 20 that are provided
in the camera body 1, and FIG. 4 is an exploded perspective view
of the mirror box 20 and the associated components. The mirror box
20 is provided therein with a main mirror (quick-return mirror)
21 which is pivoted about a horizontally-extending mirror shaft
21b to be swingable horizontally. The main mirror 21 is in a lower
position (shown in FIGS. 5 and 6) in which the main mirror 21 lies
on the optical axis of the photographing lens 2 at the angle of
approximately 45 degrees in a normal state. In this state, the main
mirror 21 reflects the incident light, which is passed through the
photographing lens 2 and incident on the main mirror 21, upward
to be formed on a focusing screen 25 shown in FIGS. 5 and 6 (not
shown in FIGS. 3 and 4). When the main mirror 21 rotates so as to
rise, the main mirror 21 is positioned in an upper position (retracted
position shown in FIGS. 8 and 9) in which the main mirror 21 has
fully retracted from an optical path of the photographing lens 2,
in which an object light passes, to allow this object light to be
incident on an image pickup device 14 (see FIG. 13; not shown in
FIGS. 3 and 4) behind the mirror box 20 to be formed as an object
image on the image pickup device 14 so that the image pickup device
14 photoelectrically converts the object light into an image signal
to output this image signal. The image pickup device 14 can be composed
of a CCD.
[0041] The focusing screen 25 is installed in the mirror box 20
in an upper space thereof, and a pentagonal prism 22 for changing
an object image formed on the focusing screen 25 to an erect image
is installed in the mirror box 20 immediately above the focusing
screen 25. The camera body 1 is provided behind the pentagonal prism
22 with a photometering lens 23 (see FIGS. 3 and 4), a photometering
element 24 and an eyepiece 28 (see FIG. 13). The camera body 1 is
provided between the mirror box 20 and the aforementioned image
pickup device 14 with a shutter unit 30. The shutter unit 30 is
provided with a shutter drive mechanism 31 which drives a focal
plane shutter provided in the shutter unit 30 so that the focal
plane shutter opens and shut, which allows a photographing operation
to occur at the image pickup device 14. The camera body 1 is provided
on the left side (as viewed from the front of the camera body 1;
this side is hereinafter referred to as the left side) of the mirror
box 20 with a diaphragm drive mechanism 40 for actuating an iris
diaphragm 201 (see FIG. 13) provided in the photographing lens 2
and a mirror drive mechanism 50 for swinging the main mirror 21
vertically.
[0042] A diaphragm drive mechanism support plate 41 is fixed to
the left side of the mirror box 20 by set screws 42. The diaphragm
drive mechanism 40 is provided with a diaphragm drive motor 43 serving
as a drive source for driving the diaphragm drive mechanism 40,
and the mirror drive mechanism 50 is provided with a mirror drive
motor 51 serving as a drive source for driving the mirror drive
mechanism 50. The diaphragm drive motor 43 and the mirror drive
motor 51 are supported by the diaphragm drive mechanism support
plate 41. The diaphragm drive mechanism 40 is mechanically linked
with a stop-down lever (not shown) of the photographing lens 2 attached
to the lens mount 3 to make the diaphragm 201 operate by a rotating
action of the diaphragm drive motor 43. This linkage mechanism is
similar in structure to those of conventional digital SLR cameras,
and accordingly, the description of the linkage mechanism is omitted
from the following description. However, the diaphragm drive mechanism
40 is configured to operate independently of the mirror drive mechanism
50 to allow the diaphragm 201 to be adjusted at anytime for capturing
object images via the image pickup device 14 independently of operations
of the main mirror 21.
[0043] The mirror drive mechanism 50 is arranged on the left side
of the mirror box 20 between the diaphragm drive mechanism support
plate 41 and the mirror box 20. A light shield screen drive mechanism
60 is integrated into the mirror drive mechanism 50. FIG. 5 is a
perspective view of elements of the mirror drive mechanism 50 and
the light shielding screen drive mechanism 60. FIG. 6 is a side
elevational view of these elements viewed from the left side of
the camera body 1. The focusing screen 25 is positioned directly
above the main mirror 21 in the mirror box 20. The mirror drive
mechanism 50 and the light shielding screen drive mechanism 60 are
provided with a gear train 52 including a plurality of gears GA
through GK (GA, GB, GC, GD, GE, DF, GG, GH, GI, GJ and GK). The
gear GA is fixedly fitted on the rotary shaft of the mirror drive
motor 51 that is supported by the diaphragm drive mechanism support
plate 41. The gears GB and GC are integral with each other to be
formed as a first double gear, the gears GD and GE are integral
with each other to be formed as a second double gear, and the gears
GF and GG are integral with each other to be formed as a third double
gear as shown in FIGS. 5 and 6. From the gear GA to the gear GK,
the gear GA is in mesh with the gear GB of the first double gear,
the gear GC of the first double gear is in mesh with the gear GD
of the second double gear, the gear GE of the second double gear
is in mesh with the gear GF of the third double gear, the gear GG
of the third double gear is in mesh with the gear GH, the gear GH
is in mesh with the gear GJ, and the gear GJ is in mesh with the
gear GK. The rotary power of the mirror drive motor 51 is transferred
to the gear GK of the gear train 52. Among the gears GA through
GK of the gear train 52, the gear GI (shown by a broken line in
FIGS. 6 and 9) is formed integral with a shutter charge cam 54 to
make the shutter charge cam 54 rotate integrally with the gear GI.
The shutter charge cam 54 is engaged with an engaging portion 53a
of a shutter charge lever 53 positioned adjacent to the gear GI.
The shutter charge lever 53 is biased to rotate counterclockwise
as viewed in FIG. 6 by a spring device (not shown). A clockwise
rotation of the gear GI causes the shutter charge cam 54 to rotate
together in the same rotational direction to thereby charge the
shutter. This mechanism is similar in structure to those of conventional
SLR digital cameras, and accordingly, the description of this mechanism
is omitted from the following description.
[0044] The gear GJ (shown by a broken line in FIGS. 6 and 9) is
formed integral with a shutter lock release cam 56 to make the shutter
lock release cam 56 rotate integrally with the gear GJ. The shutter
lock release cam 56 is engaged with an engaging portion 55a of a
shutter lock release lever 55 positioned adjacent to the gear GJ.
The shutter lock release lever 55 is biased to rotate counterclockwise
as viewed in FIG. 6 by a spring device (not shown). A part of the
shutter lock release lever 55 in the vicinity of the left end thereof
as viewed in FIG. 6 is positioned immediately below an engaging
portion 21a of the main mirror 21 to be engaged therewith. The main
mirror 21 is biased to rotate clockwise as viewed in FIG. 6 by a
spring device (not shown). The biasing force of this spring device
brings the main mirror 21 to be held in the aforementioned lower
position thereof, in which the main mirror 21 lies on the optical
axis of the photographing lens 2. When the main mirror 21 is in
the lower position, the engaging portion 21a of the main mirror
21 is in contact with the shutter lock release lever 55. A counterclockwise
rotation of the gear GJ as viewed in FIG. 6 causes the shutter lock
release cam 56 to rotate together therewith in same rotational direction.
This counterclockwise rotation of the shutter lock release cam 56
causes the shutter lock release lever 55 to rotate clockwise, and
subsequently this clockwise rotation of the shutter lock release
lever 55 causes the main mirror 21 to rotate upward (counterclockwise
as viewed in FIG. 6) about the mirror shaft 21b via the engagement
of the engaging portion 21a with the shutter lock release lever
55 so that the main mirror 21 rises to the aforementioned upper
position (shown in FIGS. 8 and 9), in which the main mirror 21 has
fully retracted from a position on the optical axis of the photographing
lens 2.
[0045] As shown in FIGS. 7A and 7B, that show external perspective
views of the gears GJ and GK in different states, the gear GJ is
provided, on a part of the outer edge thereof in a half range of
this outer edge in the axial direction of the gear GJ, with a toothless
portion 57 on which none of the gear teeth 58 of the gear GJ are
formed. The gear GK is provided on a part of the outer edge thereof
with a toothed sector portion 59 which does not mesh with the gear
teeth 58 when the toothless portion 57 faces the gear GK, i.e.,
which meshes with the gear teeth 58 only when the toothless portion
57 does not face the gear GK. Upon the gear GJ being rotated to
a predetermined rotational position counterclockwise as viewed in
FIG. 7A, the gears GJ and GK are engaged with each other so that
rotation of the gear GJ is transferred to the gear GK. If the gear
GJ is further rotated counterclockwise to a rotational position
shown in FIG. 7B, the gear teeth 58 of the gear GJ and the toothed
sector portion 59 of the gear GK are disengaged from each other,
thus causing the gear GK to enter a free rotational state and face
the toothless gear portion 57.
[0046] The light shield screen drive mechanism 60 is provided with
a large-diameter winding pulley PA and a small-diameter driving
pulley PB. The winding pulley PA is formed integral with the gear
GK to be coaxial therewith. The camera body 1 is provided in the
vicinity of the mirror shaft 21b with a light-shield-screen shaft
61 which is parallel to the mirror shaft 21b, and the driving pulley
PB is fixedly fitted on the light-shield-screen shaft 61 to be supported
thereby. The light-shield-screen shaft 61 is located at a position
facing the lower surface of the focusing screen 25 in the vertical
direction of the camera body 1 to be capable of rotating on the
axis of the light-shield-screen shaft 61 relative to the camera
body 1. A light shield screen 62 is wound around the light-shield-screen
shaft 61. The light shield screen 62 is made of a thin opaque flexible
film or sheet and has dimensions enabling the light shield screen
62 to cover the reflecting surface of the main mirror 21. A part
of the light shield screen 62 is extended in a strip shape to be
formed as a guide belt 63. An end of the guide belt 63 is fixed
to a part of the outer edge of the winding pulley PA. The left end
of the light-shield-screen shaft 61 (i.e., on one of the opposite
ends of the light-shield-screen shaft 61 which is adjacent to the
mirror drive mechanism 50) extends through the diaphragm drive mechanism
support plate 41, and the drive pulley PB is fixedly fitted on the
left end of the light-shield-screen shaft 61 to be supported thereby.
A narrow drive belt 64 is wound around the drive pulley PB. An extension
coil spring 65 is installed between the end of the drive belt 64
and a part of the diaphragm drive mechanism support plate 41. The
winding pulley PA is provided on one side thereof with a stop pin
66. When the winding pulley PA rotates, the stop pin 66 comes in
contact with a stationary portion of the mirror box 20 to limit
the position of the light shield screen 62 that is wound around
the light-shield-screen shaft 61 by the spring force of the extension
coil spring 65.
[0047] In the mirror drive mechanism 50 and the light shield screen
drive mechanism 60, upon the mirror drive motor 51 rotating at a
shutter release or at the time that the main mirror 21 is operated
to rise to the upper position upon the user turning ON the EL display
ON/OFF button 12 or turning ON a mirror switch (not shown), rotation
of the gear GA by rotation of the mirror drive motor 51 is transferred
to the gear GJ via the intermediate gears GB through GI to rotate
the gear GJ counterclockwise, and this counterclockwise rotation
of the gear GJ causes the shutter lock release lever 55 to rotate
clockwise against the spring force of the aforementioned associated
spring device, thus causing the main mirror 21 to rise to the upper
position as shown in FIGS. 8 and 9 which show a perspective view
and a left side elevational view of the elements of the mirror drive
mechanism 50 and the light shielding screen drive mechanism 60.
Upon the gear GJ being rotated counterclockwise to a predetermined
rotational position, the toothless portion 57 of the gear GJ is
positioned off (away from) the toothed sector portion 59 of the
gear GK and the gear teeth 58 of the gear GJ are engaged with the
toothed sector portion 59 of the gear GK so that the gear GK rotates
clockwise. This rotation of the gear GK causes the winding pulley
PA that is integral with the gear GK to rotate clockwise to wind
the guide belt 63 of the light shield screen 62 around the winding
pulley PA. Accordingly, the light shield screen 62 is drawn from
the light-shield-screen shaft 61 so as to cover the reflecting surface
of the main mirror 21. This drawing movement of the light shield
screen 62 causes the light-shield-screen shaft 61 to rotate on the
axis thereof, and this rotation of the light-shield-screen shaft
61 causes the drive belt 64 to be wound around the drive pulley
PB while extending the extension coil spring 65.
[0048] Upon the completion of an exposure or (at the time that
the main mirror 21 is manually operated to move down to the lower
position upon the user turning ON the EL display ON/OFF button 12
or turning ON a mirror switch (not shown), a further rotation of
the mirror drive motor 51 causes the gear GJ to further rotate counterclockwise,
thus causing the main mirror 21 to move down to the lower position
so that the main mirror 21 returns to the normal position (initial
position) on the optical axis of the photographing lens 2. At the
same time, the counterclockwise rotation of the gear GJ causes the
toothless portion 57 thereof and the toothed sector portion 59 of
the gear GK to face each other, thus causing the gear GJ and the
gear GK to be disengaged from each other so that each of the gear
GK and the winding pulley PA enters a free state. Therefore, the
drive belt 64 is pulled by the spring force of the extension coil
spring 65, so that the drive pulley PB rotates counterclockwise
together with the gear GK while the light-shield-screen shaft 61
that is integral with the drive pulley PB rotates counterclockwise.
Consequently, the light shield screen 62 is wound around the light-shield-screen
shaft 61 to be retracted from the space immediately below the focusing
screen 25 to thereby return to the initial state.
[0049] FIG. 10 is a perspective external view of the focusing screen
25 that is installed in the mirror box 20, FIG. 11A is a cross sectional
view of the focusing screen 25 and FIG. 11B is an enlarged cross
sectional view of a portion of the focusing screen 25. The focusing
screen 25 is provided with a rectangular image forming plate 26
and a rectangular EL display 27 which is formed to extend over substantially
the entire front surface (upper surface as viewed in FIGS. 11A and
11B) of the image forming plate 26 except the peripheral edge of
the front surface thereof. The EL display 27 is embedded in a shallow
recess 261 formed on the front surface of the image forming plate
26. The image forming plate 26 is made of a transparent resin plate
(e.g., PMMA (acrylic resin) or PC (polycarbonate resin)) having
a thickness of approximately 1 millimeter, a front surface of the
image forming plate 26 (specifically the bottom surface in the recessed
portion 261) is formed to be a light diffusing surface 262 that
allows the photographer to see an image formed on the light diffusing
surface 262. Specifically, the light diffusing surface 262 is made
by roughening the front surface of the image forming plate 26 (the
bottom surface in the recessed portion 261) by forming thereon microscopic
asperities 262a in the size range of approximately two micrometers.
The image forming plate 26 is formed to also serve as an optical
condenser; a back surface 263 (lower surface as viewed in FIGS.
11A and 11B) of the image forming plate 26 is formed as a lens surface
or a Fresnel lens surface.
[0050] The EL display 27 is constructed as a full-color EL display
and is provided thereon with a matrix of red (R), green (G) and
blue (B) pixels 270 arranged in a plane. As shown in FIG. 12 that
shows a portion of one pixel 270, each pixel 270 has a multilayer
structure. As shown in FIG. 12, the EL display 27 is provided with
a transparent EL substrate (transparent substrate) 271, a transparent
outer film 26, and an EL portion 272. The transparent EL substrate
271 is made of a transparent film and serves as a film base of the
EL display 27. The EL portion 272 is made of the aforementioned
array of pixels 270 arranged two-dimensionally on a surface (lower
surface as viewed in FIG. 12) of the transparent EL substrate 271.
A moisture-proof barrier film 273 is formed on the lower surface
of the transparent EL substrate 271 and a transparent substrate-side
electrode film 274 is formed on the lower surface of the moisture-proof
barrier film 273. In addition, an insulating layer 275, a luminous
layer 276 and an insulating layer 277 are layered in that order
on the substrate-side electrode film 274 to correspond to each pixel
270. The substrate-side electrode film 274 is a transparent film
made of ITO (Indium Tin Oxide), has a thickness of 25 to 100 nanometers
and is formed on the moisture-proof barrier film 273 in a predetermined
pattern. Additionally, a transparent front-side electrode 278 is
formed on the insulating layer 277, and thereafter the remaining
outer surfaces of the substrate-side electrode film 274, the insulating
layer 275 and the front-side electrode 278 are fully coated with
a moisture-proof barrier layer 279. The front-side electrode 278
is a transparent film made of IZO (Indium Zinc Oxide) and has a
thickness of 25 to 100 nanometers. In the EL display 27, the luminous
layer 276 of each pixel 270 emits light (red, green and/or blue
lights) by applying a high-strength electric field to the luminous
layer 276 by applying a predetermined voltage between the substrate-side
electrode film 274 and the front-side electrode 278. Therefore,
selectively making the desired pixels 270 emit light makes it possible
to bring the EL display 27 to display a desired color pattern (color
image). The EL display 27 remains transparent when no voltage is
applied between the substrate-side electrode film 274 and the front-side
electrode 278.
[0051] The transparent EL substrate 271 is formed a transparent
resin film made of, e.g., one of the following resin materials:
PET (polyethylene terephthalate), PES (polyethersulfone), PAr (Polyarylate)
and PC (polycarbonate) with a thickness of approximately 75 micrometers.
Each of the insulating layers 275 and 277 is formed a silicon dioxide
film having a thickness of 0.2 to 0.3 micrometers, while each of
the moisture-proof barrier films 273 and 279 is formed from a silicon
nitride film having the same degree of thickness as each of the
insulating layers 275 and 277. The luminous layer 276 has a thickness
of 0.5 to 1.0 micrometers. If the luminous layer 276 is made as
inorganic EL, the red pixel is made of CaS:Eu, ZnS:Sm and the like,
the green pixel is made of Zn:Tb and the like and the blue pixel
is made of SrS:Ce, CaGa.sub.2S.sub.4:Ce and the like. If the luminous
layer 276 is made as organic EL, the red pixel is made of Eu(DBM).sub.3(Phen)
(Eu complex), the green pixel is made of Alq (Tris(8-quinolinolato)aluminum)
and the blue pixel is made of DPVBi (distyrylarylene derivative).
[0052] The EL display 27 having the above described structure is
embedded in the recess 261 of the image forming plate 26 with the
front side (the lower side as viewed in FIGS. 11A and 11B) of the
EL display 27 facing the rear surface of the image forming plate
26. A transparent sealant (not shown) is filled in the gap between
the recessed portion of the image forming plate 26 and the EL display
27 to seal the gap therebetween and to form the image forming plate
26 and the EL display 27 integral with each other to thereby constitute
the focusing screen 25.
[0053] FIG. 13 is a block diagram of components of the SLR digital
camera shown in FIGS. 1 and 2. An object image is formed on the
image pickup device 14 via the photographing lens 2 and an optical
low-pass filter 141, and the image pickup device 14 picks up this
object image formed thereon to output an image signal. This image
signal is converted into a digital image signal by an A/D converter
101. This digital image signal is subjected to predetermined signal
processing such as a color processing and a gamma control processing
in a signal processing circuit 102. Subsequently, this processed
digital signal is compressed or not compressed in a compressing
circuit 103 before being written into a VRAM (image memory) 104.
It is possible to set an accumulation time (integral action time)
at the image pickup device 14 at a time of exposure by controlling
a CCD driver 105 via a clock generator 106 by a CPU 100.
[0054] The CPU 100 controls the operation of an AF (autofocus)
drive mechanism 112 based on an object distance measured by a distance
measuring device 111 when an object image is taken (captured). Additionally,
the CPU 100 controls the operation of a mirror drive mechanism 50
to drive the main mirror 21, and the CPU 100 controls the operation
of rotation of the shutter lock release lever 55 to charge the shutter
and subsequently release the shutter, and simultaneously the CPU
100 controls the operation of a shutter drive circuit 114 so that
the shutter unit 30 opens and shuts the shutter. At the same time,
the CPU 100 controls the operation of a diaphragm drive mechanism
40 to stop down a diaphragm 201 provided in the photographing lens
2. In addition, the CPU 100 operates to make each of the information-indicating
LCD panel 8 and the external LCD monitor 11 display required data.
The CPU 100 also controls the operation of a flash controller 116
for controlling the discharge of a flash 115 that is a built-in
flash or an external flash. Additionally, the CPU 100 controls the
operation of an exposure controller 117 based on a photometric signal
output from the photometering element 24.
[0055] Information on the operation of the main switch 4, ON/OFF
switch information on a combination photometering/release switch
500 including a photometering switch 500a and a release switch 500b
which are turned ON when the release button 5 is halfway and fully
depressed, respectively, and mode information on selected modes
which are manually selected with the mode select dial 7 are all
input to the CPU 100. Additionally, information on the operation
of the EL display ON/OFF button 12 for displaying a required image
is input to the CPU 100. The camera body 1 is further provided therein
with an EL drive circuit 118 which drives the EL display 27 that
is integral with the focusing screen 25 to make the EL display 27
display a required image. It is possible that the CPU 100 make the
EL drive circuit 118 operate so that the EL display 27 displays
a required image upon the mode select dial 7 or the EL display ON/OFF
button 12 being operated. In addition, the CPU 100 can control the
operation of the light shield screen drive mechanism 60 to insert
and retract the light shield screen 62 into and from the space immediately
below the focusing screen 25.
[0056] Operations of the SLR digital camera having the above described
structure will be hereinafter discussed with reference to the flow
charts shown in FIGS. 14A and 14B. This control is carried out when
the main switch 4 is turned ON. Firstly, an EL display flag fEL
is set to zero (fEL=0) (step S101). Subsequently, it is determined
whether the photographing lens 2 is of a type having an image stabilizing
capability (step S104), and thereafter it is determined whether
the EL display ON/OFF button 12 has not been operated to be turned
ON (step S105) if it is determined at step S104 that the photographing
lens 2 is not of a type having an image stabilizing capability (if
YES at step S104). If it is determined that the photographing lens
2 is not of a type having an image stabilizing capability (if YES
at step S104) and it is further determined that the EL display ON/OFF
button 12 has not been operated (if YES at step S105), control proceeds
to step S112 at which an optical image display control flow "F1"
starts. On the other hand, if the photographing lens 2 is of a type
having an image stabilizing capability (if NO at step S104) or if
the EL display ON/OFF button 12 has been operated (if NO at step
S105), control proceeds to step S121 at which an EL display control
flow "F2" starts.
[0057] The operations of the optical image display control flow
F1 are identical to those in conventional SLR digital cameras. Before
control enters the optical image display control flow "F1",
the SLR digital camera in is a state where the main mirror 21 is
in the lower position while the light which is passed through the
photographing lens 2 is reflected by the main mirror 21 to be formed
on the focusing screen 25. The photographer looks into the viewfinder
window 10 to view an optical image of an object, which is formed
on the focusing screen 25 via the photographing lens 2, through
the pentagonal prism 22 and the eyepiece 28. Upon the release button
5 being depressed halfway to thereby turn ON the photometering switch
500a (step S112, Y), the AF drive mechanism 112 is driven to adjust
the focus of the photographing lens 2 in accordance with an object
distance measured using the distance measuring device 111 (step
S113), and a photometering operation is performed with the photometering
element 24 to determine an f-number and a shutter speed (step S114).
Subsequently, upon the release button 5 being fully depressed to
thereby turn ON the release switch 500b (step S115, Y), the mirror
drive mechanism 50 is actuated so that the main mirror 21 rises
(step S116). Upon the main mirror 21 rising to the upper position,
the shutter drive mechanism 31 is actuated to open the focal plane
shutter of the shutter unit 30 so that the image pickup device 14
picks up an object image formed thereon via the photographing lens
2 (step S130). This object image picked up by the image pickup device
14 is written as image data into the image memory 104 (step S131).
Thereafter, it is determined whether the main switch 5 is OFF (step
S132). If the main switch 5 is ON (if NO at step S132), control
returns to step S104. If the main switch 5 is OFF (if YES at step
S132), control ends.
[0058] At step S130, when a predetermined exposure time has lapsed,
the shutter drive mechanism 31 is actuated to close the focal plane
shutter of the shutter unit 30 and the mirror drive mechanism 50
is actuated so that the main mirror 21 is moved down.
[0059] In the optical image display control flow "F1",
if the photometering switch 500a is not turned ON (step S112, N)
control proceeds to step S132, or if after the photometering switch
500a is turned ON, the release switch 500b is not turned ON (step
S115, N), and the photometering switch 500a is turned OFF, control
proceeds to step S132.
[0060] On the other hand, upon control entering the EL display
control flow "F2", it is determined whether the EL display
flag fEL is equal to zero (fEL=0) (step S121). If the display flag
fEL is zero (fEL=0) (if YES at step S121), the mirror drive mechanism
50 is actuated so that the main mirror 21 rises (step S122) and
the EL display flag fEL is set to 1 (step S122a). Upon the main
mirror 21 rising to the upper position, the shutter drive mechanism
31 is actuated to open the focal plane shutter of the shutter unit
30 and the image pickup device 14 picks up an object image formed
thereon via the photographing lens 2. If the display flag fEL is
not zero (if NO at step S121), control skips step S122 because the
main mirror 21 has already risen to the upper position. Subsequently,
upon the release button 5 being depressed halfway to thereby turn
ON the photometering switch 500a (step S123, Y), a contrast-based
AF operation in which the AF drive mechanism 112 is driven to adjust
the focus of the photographing lens 2 based on contrast values obtained
from the image signals of an object image obtained via the image
pickup device 14 (step S124). Subsequently, a photometering operation
is performed to measure the brightness of the object image from
the light received by elements of the CCD that constitutes the image
pickup device 14 (step S125). The image signal obtained via the
image pickup device 14 is subjected to predetermined signal processing
as mentioned above to obtain a visual image of the object. At this
time, the EL drive circuit 118 is driven so that the object image
is displayed as a live digital image on the EL display 27 (step
S126). Consequently, the photographer can view this object image
through the pentagonal prism 22 and the eyepiece 28 since the object
image is displayed in full color on the focusing screen 25 by the
EL display 27. At this time, it is possible to make the external
LCD monitor 11 display the same object image (live digital image)
(step S127). Subsequently, control proceeds to step S133 to pick
up an object image by the image pickup device 14 upon the photographer
fully depressing the release button 5 while viewing the object image
displayed in the field of view of the viewfinder by the EL display
27 (step S128, Y).
[0061] At step S133, the image pickup device 14 picks up an object
image formed thereon via the photographing lens 2 for a predetermined
exposure time (electronic shutter). This object image picked up
by the image pickup device 14 is written as image data into the
image memory 104 (step S134).
[0062] Thereafter, it is determined whether the main switch 5 is
OFF (step S135). If the main switch 5 is OFF (if YES at step S135),
the mirror drive mechanism 50 is actuated so that the main mirror
21 moves down to the lower position, actuates the shutter drive
mechanism 31 to close the focal plane shutter of the shutter unit
30, and stops the operation of the EL drive circuit 118 (step S140),
and control ends. If the main switch 5 is ON (if NO at step S135),
control proceeds to step S136.
[0063] At step S136, it is determined whether the photographing
lens 2 is of a type having an image stabilizing capability (step
S136), and thereafter it is determined whether the EL display ON/OFF
button 12 has not been operated to be turned ON (step S137). If
the photographing lens 2 is of a type having an image stabilizing
capability (if NO at step S136) or if the EL display ON/OFF button
12 has been operated (if NO at step S137), control proceeds to step
S121 and repeat the EL display control flow "F2".
[0064] If it is determined that the photographing lens 2 is not
of a type having an image stabilizing capability (if YES at step
S136) and it is further determined that the EL display ON/OFF button
12 has not been operated (if YES at step S137), control proceeds
to step S138.
[0065] At step S138, the mirror drive mechanism 50 is actuated
so that the main mirror 21 moves down to the lower position, actuates
the shutter drive mechanism 31 to close the focal plane shutter
of the shutter unit 30, and stops the operation of the EL drive
circuit 118, (step S138).
[0066] Subsequently, the EL display flag fEL is set to zero (step
S139) and control returns to step S103.
[0067] The Lift Mirror Process performed at steps S116 and S122
will be hereinafter discussed in detail with reference to the flow
chart shown in FIG. 15A. The mirror drive mechanism 50 is actuated
so that the main mirror 21 rises to the upper position and the shutter
drive mechanism 31 is actuated so that the focal plane shutter of
the shutter unit 30 is opened (step S201), the shutter drive mechanism
31 is actuated to open the focal plane shutter of the shutter unit
30 (step S202) and the CPU 100 actuates the EL drive circuit 118
at the same time (step S203). The operation of the mirror drive
mechanism 50 following the actuation thereof at step S201 causes
the light shield screen drive mechanism 60 to be driven to make
the light shield screen 62 advance into the space between the main
mirror 21 which is in the upper position and the focusing screen
25. Due to this insertion of the light shield screen 62, the reflecting
surface of the main mirror 21 is covered by the light shield screen
62. Consequently, when the EL display 27 that is incorporated in
the focusing screen 25 displays an image, the light of this image
which emerges downward from the EL display 27 is not reflected by
the main mirror 21, and accordingly, only an image which is formed
by the light emerging upward from the EL display 27 is seen through
the viewfinder, which enhances the image quality.
[0068] The Down Mirror Process performed at steps S138 and S140
will be hereinafter discussed in detail with reference to the flow
chart shown in FIG. 15B. The mirror drive mechanism 50 is actuated
so that the mirror moves down to the lower position (step S204),
the shutter drive mechanism 31 is actuated to close the focal plane
shutter of the shutter unit 30 (step S205) and the CPU 100 stops
the operation of the EL drive circuit 118 (step S206). At the same
time, the light shield screen 62 is wound around the light-shield-screen
shaft 61 by the operation of the light shield screen drive mechanism
60 to be retracted from the space between the main mirror 21 and
the focusing screen 25 to thereby allow an optical object image
which is reflected by the main mirror 21 to be focused on the focusing
screen 25.
[0069] Note that control proceeds to the EL display control flow
"F2" unconditionally if it is determined at step S104
in the flow chart shown in FIG. 14A that the photographing lens
2 is of a type having an image stabilizing capability. Since photographing
lenses having an image stabilizing capability are configured so
as to counteract vibrations of an object image to prevent image
shake from occurring, an optical image of an object which is formed
on the focusing screen 25 via the photographing lens 2 slightly
vibrates on the focusing screen 25 and such vibrations may cause
the photographer to get finder-view motion sickness if the photographing
lens 2 is of a type having an image stabilizing capability and if
the photographer takes pictures while observing the optical object
image on the focusing screen 25 through the viewfinder during the
control by the optical image display control flow "F1".
To prevent this problem from occurring, if the photographing lens
2 is of a type having an image stabilizing capability, making control
proceed to the EL display control flow F2 makes it possible to prevent
the photographer from getting finder-view motion sickness even if
an object image is formed on the focusing screen 25 because this
object image is a stabilized live digital image obtained via the
image pickup device.
[0070] As described above, in the above illustrated embodiment
of the SLR digital camera, the viewfinder does not have to be provided
with any switching mechanism such as shown in the aforementioned
first publication (Japanese unexamined patent publication H10-294888)
for switching between an optical image and a live digital image
since the EL display 27 that is an extremely-thin display is formed
integral with the focusing screen 25 so that an object image captured
by the image pickup device 14 is displayed on the focusing screen
25 by the EL display 27 to be viewed through the viewfinder. Moreover,
in the above illustrated embodiment of the SLR digital camera, the
light shield screen drive mechanism 60 is provided so as to be associated
with the mirror drive mechanism 50 so that the light shield screen
drive mechanism 60 operates integrally with the mirror drive mechanism
50; accordingly, a complicated structure of the light shield screen
drive mechanism 60 is avoided.
[0071] Simultaneously with an optical image of an object which
is formed on the focusing screen 25 via the photographing lens 2
viewed through the viewfinder, it is possible to make the EL display
27 display photographic information such as an f-number and a shutter
speed on the focusing screen 25 within an area thereof which does
not interfere with the aforementioned optical image even when the
optical image display control flow F1 is executed.
[0072] Obvious changes may be made in the specific embodiment of
the present invention described herein, such modifications being
within the spirit and scope of the invention claimed. It is indicated
that all matter contained herein is illustrative and does not limit
the scope of the present invention.
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