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Digital Camera Patent Abstract
In an electronically zoomable digital camera having a hand shake
correction mechanism, when electronic zoom operates, pixel shift
is carried out in such manner of capturing a reference image and
then capturing a shifted image after moving an image capturing element
from the reference image by a prescribed amount of shift by means
of the hand shake correction mechanism and thereafter interpolating
pixels of the shifted image between pixels of the reference image.
The amount of shift is changed according to a magnification of the
electronic zoom. The hand shake correction mechanism has a continuous
mode in which the movement is effected by a continuous amount and
a fixed amount mode in which movement is effected by only a fixed
amount and is driven in the fixed amount mode when the pixel shift
is carried out.
Digital Camera Patent Claims
1. An electronically zoomable digital camera having a hand shake
correction mechanism for moving an optical member or an image capturing
element to correct hand shake, wherein, when electronic zoom operates,
pixel shift is carried out in such manner of capturing a reference
image that serves as a reference and then capturing a shifted image
after moving the optical member or the image capturing element from
the reference image by a prescribed amount of shift by means of
the hand shake correction mechanism and thereafter interpolating
pixels of the shifted image between pixels of the reference image,
the amount of shift is changed according to a magnification of the
electronic zoom, and the hand shake correction mechanism has a continuous
mode in which the movement is effected by a continuous amount and
a fixed amount mode in which movement is effected by only a fixed
amount and is driven in the fixed amount mode when the pixel shift
is carried out.
2. The digital camera as claimed in claim 1, wherein the hand shake
correction mechanism is driven by a piezoelectric element, a square
wave voltage is applied to the piezoelectric element in the continuous
mode, and a triangular wave voltage of a wavelength longer than
that of the square wave voltage is applied to the piezoelectric
element only once per movement in the fixed amount mode.
3. The digital camera as claimed in claim 1, wherein the amount
of shift is expressed by a total amount of a horizontal shift amount
"dh" in a horizontal direction and a shift amount "dv"
in a vertical direction, and assuming that a horizontal pixel pitch
is "ph", a vertical pixel pitch is "pv", a horizontal
interpolation multiple is "k" and a vertical interpolation
multiple is "l" with respect to the image capturing element
and integers "m" and "n" are used, then the
equations: dh=ph.times.(m+1/k); and dv=pv.times.(n+1/l) hold.
4. The digital camera as claimed in claim 1, wherein the digital
camera comprises a movement amount detection section for detecting
an actual amount of movement of the optical member or the image
capturing element by the hand shake correction mechanism, and the
pixel shift corrects the shifted image by the actual amount of movement
detected by the movement amount detection section.
5. An electronically zoomable digital camera having a hand shake
correction mechanism for moving an optical member or an image capturing
element to correct hand shake, wherein, when electronic zoom operates,
pixel shift is carried out in such manner of capturing a reference
image that serves as a reference and then capturing a shifted image
after moving the optical member or the image capturing element from
the reference image by a prescribed amount of shift by means of
the hand shake correction mechanism and thereafter interpolating
pixels of the shifted image between pixels of the reference image,
and the hand shake correction mechanism comprises a movement amount
regulation section for effecting mechanical regulation so that the
amount of movement of the optical member or the image capturing
element does not exceed the amount of shift when the pixel shift
is carried out.
6. The digital camera as claimed in claim 5, wherein the movement
amount regulation section is composed of a projection and a frame
that surrounds the projection.
7. The digital camera as claimed in claim 5, wherein the movement
amount regulation section has a mechanism by which it is advanced
and retreated.
8. The digital camera as claimed in claim 5, wherein the pixel
shift is carried out by using the movement amount regulation section
in a case of a prescribed electronic zoom magnification.
Digital Camera Patent Description
RELATED APPLICATION
[0001] This application is based on Japanese Patent Application
No. 2004-310887, the content of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a digital camera.
[0003] Many digital cameras, in which an image formed on an image
capturing element is converted into electronic data and recorded,
are provided with "electronic zoom" for obtaining a pseudo
enlarged image whose angle of view of the image picked up by cutting
a partial image out of the image formed on the image capturing element
and recording the partial image is reduced. However, there is a
problem that the pixels of the image are reduced in number to disadvantageously
lead to a degraded resolution when the electronic zoom is used.
[0004] Moreover, as a means for obtaining an image of high resolution
higher than the resolution of the image capturing element, "pixel
shift" for synthesizing a high-resolution image by continuously
capturing a plurality of images of different image capturing ranges
by an equally divided amount of pixel pitch and interpolating the
pixels of another image between the pixels of one image is well
known.
[0005] Moreover, "hand shake correction" for obtaining
a clear image by providing a drive mechanism for moving the image
capturing element or an optical member and a shake amount detection
section for detecting the amount of shake of the digital camera
itself in order to solve the problem of hand shake that the captured
image becomes indistinct due to the shake of the digital camera
itself and canceling the shake of the digital camera with the movement
of the image capturing element or the optical member is also well
known.
[0006] Furthermore, a technique for providing a digital camera
with a drive mechanism for moving the image capturing element or
an optical member and carrying out both the "hand shake correction"
and the "pixel shift" by means of the drive mechanism
is disclosed in Japanese Patent Laid-Open Publications No. 2001-223932
or H07-287268. However, no consideration for the degradation in
resolution due to the electronic zoom is provided in these documents.
SUMMARY OF THE INVENTION
[0007] Accordingly, the object of the present invention is to provide
a digital camera capable of obtaining a high-resolution image during
the electronic zoom.
[0008] In order to achieve the object, in a first aspect of the
present invention, there is provided an electronically zoomable
digital camera having a hand shake correction mechanism for moving
an optical member or an image capturing element to correct hand
shake, wherein, [0009] when electronic zoom operates, pixel shift
is carried out in such manner of capturing a reference image that
serves as a reference and then capturing a shifted image after moving
the optical member or the image capturing element from the reference
image by a prescribed amount of shift by means of the hand shake
correction mechanism and thereafter interpolating pixels of the
shifted image between pixels of the reference image, [0010] the
amount of shift is changed according to a magnification of the electronic
zoom, and [0011] the hand shake correction mechanism has a continuous
mode in which the movement is effected by a continuous amount and
a fixed amount mode in which movement is effected by only a fixed
amount and is driven in the fixed amount mode when the pixel shift
is carried out.
[0012] According to the construction, the pixel shift is carried
out during the electronic zoom in the digital camera, and therefore,
a high-resolution image can be obtained. Moreover, the hand shake
correction and the pixel shift are carried out by the identical
hand shake correction mechanism, and therefore, an inexpensive compact
digital camera can be provided.
[0013] Moreover, by reducing the amount of shift as the electronic
zoom magnification increases and interpolating many pixels of the
shifted images between the pixels of the reference image, the number
of interpolation pixels can be increased. Therefore, more interpolations
become possible as the number of pixels of the reference image is
reduced by the electronic zoom, and therefore, the resolution is
not degraded even if the electronic zoom is carried out.
[0014] Furthermore, followability and a wide operation range are
secured by operating the camera in the continuous mode when the
hand shake correction is carried out, and satisfactory hand shake
correction can be achieved. Moreover, a high positioning accuracy
is achieved by driving the camera in the fixed amount mode when
the pixel shift is carried out, and therefore, a shifted image suitable
for interpolating the reference image can be obtained.
[0015] In the digital camera of the first aspect of the present
invention, the hand shake correction mechanism may be driven by
at least one piezoelectric element. It is acceptable to apply the
square wave voltage to the piezoelectric element in the continuous
mode and apply the triangular wave voltage of a wavelength longer
than that of the square wave voltage to the piezoelectric element
only once per movement in the fixed amount mode.
[0016] According to the construction, it is possible to quickly
move the image capturing element by the square wave pulses of a
short wavelength in the continuous mode and reliably move the image
capturing element by the triangular wave pulse in the fixed amount
mode by the prescribed amount of shift. Therefore, a fast followability
for the hand shake correction and an accurate positioning for the
pixel shift can be made compatible.
[0017] Moreover, in the digital camera of the first aspect of the
present invention, the amount of shift is expressed by the total
amount of the horizontal shift amount "dh" in the horizontal
direction and the shift amount "dv" in the vertical direction,
and assuming that a horizontal pixel pitch is "ph", a
vertical pixel pitch is "pv", a horizontal interpolation
multiple is "k" and a vertical interpolation multiple
is "l" with respect to the image capturing element and
integers "m" and "n" are used, then the equations:
dh=ph.times.(m+1/k); and dv=pv.times.(n+1/l) may hold.
[0018] According to the construction, the positioning accuracy
can be improved by securing an amount of movement greater than the
pixel pitch even when it is mechanically difficult to carry out
accurate positioning by a movement of an amount smaller than the
pixel pitch.
[0019] Moreover, the digital camera of the first aspect of the
present invention may include a movement amount detection section
for detecting the actual amount of movement of the optical member
or the image capturing element by means of the hand shake correction
mechanism, and [0020] the pixel shift may correct the shifted image
by the actual amount of movement detected by the movement amount
detection section.
[0021] According to the construction, even if the actual amount
of movement does not completely coincide with the prescribed amount
of shift, appropriate interpolations can be carried out by correcting
the shifted image.
[0022] In a second aspect of the present invention, there is provided
an electronically zoomable digital camera having a hand shake correction
mechanism for moving an optical member or an image capturing element
to correct hand shake, wherein, when electronic zoom operates, pixel
shift is carried out in such manner of capturing a reference image
that serves as a reference and then capturing a shifted image after
moving the optical member or the image capturing element from the
reference image by a prescribed amount of shift by means of the
hand shake correction mechanism and thereafter interpolating pixels
of the shifted image between pixels of the reference image, and
[0023] the hand shake correction mechanism includes a movement amount
regulation section for effecting mechanical regulation so that the
amount of movement of the optical member or the image capturing
element does not exceed the amount of shift when the pixel shift
is carried out.
[0024] According to the construction, the pixel shift is carried
out during the electronic zoom in the digital camera, and therefore,
a high-resolution image can be obtained. Moreover, the hand shake
correction and the pixel shift are carried out by the identical
hand shake correction mechanism, and therefore, an inexpensive compact
digital camera can be provided.
[0025] Moreover, by applying a great movement torque that exceeds
the movement torque necessary for the movement by the prescribed
amount of shift to the image capturing element while effecting regulation
so that the image capturing element cannot be moved larger than
the prescribed amount of shift by the movement amount regulation
section when the pixel shift is carried out, the image capturing
element can be accurately moved by the amount of movement regulated
by the movement amount regulation section, i.e., by the prescribed
amount of shift.
[0026] In the digital camera of the second aspect of the present
invention, the movement amount regulation section may have a mechanism
by which it is advanced and retreated.
[0027] Moreover, in the digital camera of the second aspect of
the present invention, the pixel shift may be carried out by using
the movement amount regulation section in the case of a prescribed
electronic zoom magnification.
[0028] As described above, according to the present invention,
a digital camera capable of obtaining a high-resolution image interpolated
by an appropriate pixel shift during the electronic zoom can be
provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present invention will be further described with reference
to the accompanying drawings wherein like reference numerals refer
to like parts in the several views, and wherein:
[0030] FIG. 1 is a block diagram of a digital camera according
to one embodiment of the present invention;
[0031] FIG. 2 is a perspective view of a hand shake correction
device of FIG. 1;
[0032] FIG. 3 is a rear view of the hand shake correction device
of FIG. 2;
[0033] FIG. 4 is a sectional view of the hand shake correction
device of FIG. 2;
[0034] FIG. 5 is a flowchart of capturing an image in a pixel shift
mode of the digital camera of FIG. 1;
[0035] FIGS. 6A through 6C are perspective views showing the relative
relation between a regulation projection and a regulation frame
of FIG. 4;
[0036] FIG. 7 is a drive voltage waveform chart of the hand shake
correction device of FIG. 1;
[0037] FIG. 8 is a schematic view showing the relation between
a reference image and a shifted image of the digital camera of FIG.
1;
[0038] FIG. 9 is a sectional view showing the relative relation
between a regulation projection and a regulation frame of FIG. 4;
[0039] FIGS. 10A through 10D are schematic views showing the relation
between a plurality of shifted images different from the shifted
image of FIG. 8 and the reference image; and
[0040] FIG. 11 is a sectional view showing an alternative plan
of the regulation frame of FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] FIG. 1 shows the construction of a digital camera 1 of one
embodiment of the present invention. The digital camera 1 includes
a lens unit 4 that is composed of movable first lens group 2 and
second lens group 3 and is optically zoomable, a shutter 5 and an
image capturing element 6 constructed of, for example, a CCD, a
hand shake correction device 7 that is the hand shake correction
mechanism for moving the image capturing element 6, an image signal
processing section 8 for generating image data by processing an
image signal obtained by converting light received by the image
capturing element 6 into an electrical signal, a timing control
circuit 9 for controlling the operation timing of the image capturing
element 6 and the image signal processing section 8 and a control
section 10 for controlling the image signal processing section 8
and the timing control circuit 9. The digital camera 1 further includes
a shake detection section 11 for detecting the amount of shake of
the digital camera 1, an operation section 12 by which the user
gives instructions to a control section 10, a display device 13
for reproducing an image from the image data generated by the image
signal processing section 8 and displaying the image and a storage
device 14 for recording the image data generated by the image signal
processing section 8.
[0042] FIG. 2 shows the hand shake correction device 7. The hand
shake correction device 7 has a box-like shape constructed of a
front board 21 whose center facing the lens unit 4 is opened, a
rear board 22 arranged parallel to the front board 21 and two spacers
23 that constitute the end surfaces of the side portions and define
an interval between the front board 21 and the rear board 22. An
X-baseplate 25, which is transversely movably supported by an X-actuator
24 and whose center is opened, is provided for the front board 21
inside the hand shake correction device 7. Further, a Y-baseplate
27, which is vertically movably supported by a Y-actuator 26 and
holds the image capturing element 6, is provided for the X-baseplate
25 inside the hand shake correction device 7.
[0043] FIG. 3 shows the rear side of the hand shake correction
device 7 from which the rear board 22 is removed. The X-actuator
24 is a piezoelectric actuator constituted of a drive section 24a
constructed of a piezoelectric element that transversely expands
and contracts upon receiving a voltage applied thereto, a friction
member 24b that is moved in the lengthwise direction by the expansion
and contraction of the drive section 24a and a movement section
24c that is frictionally engaged with the friction member 24b. The
Y-actuator 26 is also a piezoelectric actuator similarly constituted
of a drive section 26a, a friction member 26b and a movement section
26c. A Hall element 28 and a columnar regulation projection 29 are
provided on the rear surface of the Y-baseplate 27.
[0044] Further, FIG. 4 shows the cross-section taken along the
line A-A of FIG. 3 of the hand shake correction device 7. A magnet
30 facing the Hall element 28 on the Y-baseplate 27 is provided
for the rear board 22, constituting a movement amount detection
section for detecting the amount of movement of the Y-baseplate
27 with respect to the rear board 22 by the Hall element 28. Moreover,
in the rear board 22, a regulation frame 31 is provided in a position
facing the regulation projection 29 on the Y-baseplate 27 when the
X-actuator 24 and the Y-actuator 26 are located at the origin (i.e.,
center of the movable range). The regulation frame 31, which is
positioned behind the rear end of the regulation projection 29 in
FIG. 4, is able to advance against the Y-baseplate 27 so as to surround
the periphery of the regulation projection 29 by a frame actuator
32 and retreat away from the Y-baseplate 27 as shown in FIG. 4.
The regulation projection 29 and the regulation frame 31 constitutes
a movement amount regulation section.
[0045] Operation of the digital camera 1 constructed as above will
be described next.
[0046] The digital camera 1 inputs an image signal obtained by
converting with the image capturing element 6 an image, which is
formed on the image capturing element 6, into an electrical signal
to the image signal processing section 8 and makes the image signal
processing section 8 generate image data by controlling the image
signal processing section 8 and the timing control circuit 9 by
the control section 10 according to the instructions that the user
gives by means of the operation section 12. When the hand shake
correction is carried out in the digital camera 1, the shake detection
section 11 detects the amount of shake of the digital camera 1 and
inputs the same to the control section 10. Then, the control section
10 moves the image capturing element 6 by means of the hand shake
correction device 7 so as to cancel the amount of shake inputted
from the shake detection section 11, thereby allowing the hand shake
correction to be carried out. Moreover, the digital camera 1 is
optically zoomable so as to enlarge the image formed on the image
capturing element 6 by moving the first lens group 2 and the second
lens group 3. If the enlargement ratio by the optical zoom is the
maximum, it is possible to carry out electronic zoom for obtaining
an image of a small apparent angle of view by further cutting out
only a part of the image formed on the image capturing element 6
in the image signal processing section 8. Moreover, when the hand
shake correction is not used, the digital camera 1 is able to carry
out the pixel shift for interpolating the pixels so as to compensate
for a degradation in resolution by capturing a shifted image by
moving the image capturing element 6 by a prescribed amount of shift
by the hand shake correction device 7 when the electronic zoom is
carried out.
[0047] FIG. 5 shows the flow of the operation when the digital
camera 1 is set in a pixel shift mode in which pixel shift is carried
out. In the pixel shift mode, the digital camera 1 first confirms
in step S1 whether or not the pixel shift mode is still set and
confirms in step S2 whether or not a release button of one operating
member of the operation section 12 is depressed. If the pixel shift
mode has been ended in step 1, then the processing is ended, and
image capturing operation in step S3 and the subsequent steps are
carried out upon detecting that the release button is depressed
in step S2. The confirmations in step S1 and step S2 will be repeated
until the release button is depressed. If it is detected that the
release button is depressed in step S2, then the state of the electronic
zoom is confirmed in step S3. If the electronic zoom is at the full
width, i.e., if the enlargement ratio by the electronic zoom is
one (.times.1), then the normal image capturing operation of carrying
out automatic exposure compensation and automatic focus adjustment
in step S4 and generating pickup image data by processing the signal
generated by the image capturing element 6 in the image signal processing
section 8 in step S5 is carried out. If the electronic zoom is not
at the full width, i.e., if the enlargement ratio by the electronic
zoom is greater than one, then image capturing operation for carrying
out the interpolation of the pixels by the pixel shift in steps
S6 through S11 is carried out. The image capturing operation for
carrying out the interpolation by the pixel shift is carried out
by first effecting the automatic exposure compensation and the automatic
focus adjustment in step S6 and then carrying out a capture of a
reference image for generating image data by processing the signal
generated by the image capturing element 6 in the image signal processing
section 8 in step S7. Subsequently, by first shifting the image
capturing element 6 by a prescribed amount of shift by driving the
X-actuator 24 and the Y-actuator 26 of the hand shake correction
device 7 in step S8 and then capturing the shifted image for generating
image data by processing the signal generated by the image capturing
element 6 in the image signal processing section 8 in step S9 similarly
to step 7. Then, the X-actuator 24 and the Y-actuator 26 of the
hand shake correction device 7 are restored in step S10 into the
states before they are driven in step S8, and image synthesis for
generating image data by interpolating the image data of the reference
image captured in step S7 with the image data of the shifted image
captured in step S9 is carried out in the image signal processing
section 8 in step S11. After the normal image capturing operation
in steps S4 and S5 or the image capturing operation for carrying
out the interpolation by the pixel shift in steps S6 through S11,
an after view is displayed on the display device 13 in step S12,
and the series of imaging operation is completed by recording the
captured image data in the storage device 14 in step S13. Subsequently,
the digital camera 1 repeats the confirmations in step S1 and step
S2 again, getting ready for an instruction from the user.
[0048] Although the image capturing operation for carrying out
the interpolation by the pixel shift in steps S6 through S11 is
carried out when the electronic zoom is not at the full width in
step S3 in the present embodiment, it is acceptable to carry out
the normal image capturing operation in steps S4 and S5 when the
enlargement ratio by the electronic zoom is smaller than the prescribed
enlargement ratio (when the electronic zoom magnification is smaller
than, for example, two (.times.2)) and carry out the image capturing
operation in steps S6 through S11 when the enlargement ratio by
the electronic zoom is not smaller than the prescribed enlargement
ratio (when the electronic zoom magnification is not smaller than,
for example, two (.times.2)).
[0049] Further, the driving of the image capturing element 6 by
the hand shake correction device 7 when the pixel shift is carried
out will be described in detail. If the digital camera 1 is set
so as to carry out the pixel shift, then the X-actuator 24 and the
Y-actuator 26 first support the X-baseplate 25 and the Y-baseplate
27, respectively, at the origins at the centers of respective movable
ranges, and the frame actuator 32 makes the regulation frame 31
approach the Y-baseplate 27. Then, as shown in FIG. 6A, the regulation
frame 31 enters a state in which the frame 31 surrounds the periphery
of the regulation projection 29. Then, if the X-actuator 24 is driven
so as to largely move the X-baseplate 25 in a prescribed direction
and the Y-actuator 26 is driven to largely move the Y-baseplate
27 in a prescribed direction, then the regulation projection 29
moves until it comes in contact with the regulation frame 31, and
the regulation projection 29 enters a state in which the projection
29 is brought in contact with a corner of the regulation frame 31
as shown in FIG. 6B. When the electronic zoom is not used, image
capturing is carried out in the state. When the electronic zoom
is used, the image data captured in the state is first stored as
a reference image in a memory inside the image signal processing
section 8. Further, the X-actuator 24 is driven so as to largely
move the X-baseplate 25 in the direction reversely to the previous
one, and the Y-actuator 26 is driven so as to move the Y-baseplate
27 in the direction reversely to the previous one, moving the regulation
projection 29 to a position where the projection 29 comes in contact
with the corner on the opposite side of the regulation frame 31
as shown in FIG. 6C. Since the image capturing element 6 moves together
with the regulation projection 29, the image captured in the state
of FIG. 6C becomes a shifted image of which the image capturing
range is shifted by the amount of shift determined by the dimensions
of the regulation projection 29 and the regulation frame 31 from
the foregoing reference image.
[0050] Assuming herein that the image capturing element 6 has a
square pixel of a pixel pitch of 1 .mu.m (horizontal pixel pitch
"ph"=vertical pixel pitch "pv"=1 .mu.m), the
diameter of the regulation projection 29 is 1000 .mu.m and the length
of one side of the interior of the regulation frame 31 is 1800.5
.mu.m, then a horizontal shift amount "dh" and a vertical
shift amount "dv" both becomes 800.5 .mu.m and hold the
equations: dh=ph.times.(800+1/2); and dv=pv.times.(800+1/2). That
is, the horizontal shift amount "dh" is a distance obtained
by multiplying the sum total of the integer "m" (=800)
and the reciprocal of a horizontal interpolation multiple "k"
(=2) by the horizontal pixel pitch "ph", while the vertical
shift amount "dv" is a distance obtained by multiplying
the sum total of the integer "n" (=800) and the reciprocal
of a vertical interpolation multiple "l" (=2) by the vertical
pixel pitch "pv" (1 .mu.m).
[0051] The X-actuator 24 and the Y-actuator 26 move the movement
members 24c and 26c by repeating the engagement by static friction
between the friction members 24b and 26b and the movement members
24c and 26c and a slide accompanying a dynamic friction. Therefore,
if it is attempted to extremely reduce the amount of movement, then
the movement members 24c and 26c cannot obtain a stable sliding
friction state with respect to the friction members 24b and 26b,
sometimes causing instability of the drive amount. Accordingly,
if the amount of shift during the pixel shift is set greater than
each of the pixel pitches "ph" and "pv" as in
the present embodiment, then the movement members 24c and 26c are
once reliably put in a complete sliding friction state, making it
possible to achieve a stable movement and highly accurate positioning.
[0052] When the hand shake correction is carried out in the digital
camera 1, the X-actuator 24 and the Y-actuator 26 are driven in
a continuous mode in which a square wave voltage of a short cycle
is repetitively inputted to the drive sections 24a and 26a according
to the intended amount of shift of the image capturing element 6
as shown in the upper row of FIG. 7. If a voltage of the waveform
described above is inputted, then the movement members 24c and 26c
are to repeat the frictional engagement state and the sliding friction
state every cycle with respect to the friction members 24b and 26b.
If the pixel shift is carried out in the continuous mode, it is
concerned that the positioning accuracy might be degraded as a consequence
of an excessive reduction in the amount of movement from the frictional
engagement state immediately before the contact of the regulation
projection 29 with the regulation frame 31 as described hereinbefore.
Accordingly, the digital camera 1 has a fixed amount mode in which
the X-actuator 24 and the Y-actuator 26 are driven by a triangular
wave voltage of a long cycle when the pixel shift is carried out
as shown in the lower row of FIG. 7. According to this waveform,
a slide more than the necessary amount of movement for the pixel
shift is generated to bring the regulation projection 29 in contact
with the regulation frame 31 merely by sliding once the movement
members 24c and 26c with respect to the friction members 24b and
26b, and therefore, a prescribed amount of shift can be accurately
generated.
[0053] FIG. 8 shows the relation between the reference image Ao
and the shifted image Ad at this time in a simplified form. As illustrated,
a synthetic image Af that has a pixel density two times that of
the reference image Ao (interpolation multiple "k"="l"=2)
is obtained by interpolating the reference image Ao with the shifted
image Ad. As illustrated, the pixels of m columns at one end in
the horizontal direction and the pixels of n rows at one end in
the vertical direction of the reference image cannot be used for
the synthetic image Af. Therefore, an image cutting range by the
electronic zoom is required to be within the range of the synthetic
image Af. When the pixel shift is carried out, the image signal
processing section 8 temporarily stores the image data of the reference
image Ao into the internal memory and transmits the image data of
the effective image Af obtained by interpolation with the image
data of the shifted image Ad to the control section 10. However,
if only the image data within the range to be finally cut out of
the reference image Ao by the electronic zoom is stored into the
memory and the image data stored in the memory is similarly interpolated
by using only the image data within the range to be cut out of the
shifted images Ad, then the load of the interpolation processing
becomes reduced, making it possible to achieve processing in a short
time and power saving.
[0054] Moreover, the horizontal pixel pitch "ph" and
the vertical pixel pitch "pv" may have mutually different
pitches, the horizontal interpolation multiple "k" and
the vertical interpolation multiple "l" may have mutually
different values, and the integers "m" and "n"
may have mutually different values. In such case, the following
two equations: dh=ph.times.(m+1/k); and dv=pv.times.(n+1/l) are
also required to be satisfied.
[0055] FIG. 9 shows the relation between the regulation projection
29 and the regulation frame 31, and the shifted image for obtaining
the pixel density two times that of the reference image Ao can be
obtained by moving the regulation projection 29 on the diagonal
line of the regulation frame 31 as described hereinbefore. However,
if the X-actuator 24 and the Y-actuator 26 are successively operated
to move the regulation projection 29 along the four sides of the
regulation frame 31 and bring the projection 29 in contact with
the four corners of the regulation frame 31, three shifted images
Ad as shown in FIGS. 10A, 10B and 10C can be obtained. Then, as
shown in FIG. 10D, the effective image Af, which has a pixel density
four times that of the reference image Ao, can be obtained by interpolating
the reference image Ao with the three shifted images Ad. At this
time, each of the horizontal interpolation multiple "k"
and the vertical interpolation multiple "l" still remains
two times when viewed in the respective directions, whereas the
absolute amount of shift becomes reduced to "dh" or "dv"
from "(dh.sup.2+dv.sup.2).sup.1/2=2.sup.1/2dh=2.sup.1/2dv".
If these are combined to move the regulation projection 29 on the
diagonal line of the regulation frame 31 when the enlargement ratio
by the electronic zoom is small and move the regulation projection
29 along the four sides of the regulation frame 31 to bring the
projection 29 sequentially in contact with the four corners of the
regulation frame 31 when the enlargement ratio by the electronic
zoom is great, then the number of interpolation pixels can be increased
so as to compensate for the resolution that reduces as the enlargement
ratio of the electronic zoom increases.
[0056] If the regulation projection 29 is moved only on the diagonal
line of the regulation frame 31 without changing the amount of shift
as described above, it is acceptable to provide a configuration
as shown in FIG. 11 in which two corners of the regulation frame
31 are connected by curved lines. If the regulation frame 31 is
formed into such a configuration, a force takes effect so as to
move the regulation projection 29 to the other direction by a driving
torque in either one direction even if the driving torque of either
one of the X-actuator 24 and the Y-actuator 26 is not sufficient,
and therefore, the regulation projection 29 can be more reliably
moved by a prescribed amount.
[0057] Moreover, it is acceptable to detect the actual amount of
shift of the image capturing element 6 by means of the Hall element
28, correct the pixels of the shifted image according to the actual
amount of movement, calculate the weighted mean to the surrounding
pixels to obtain the shifted image and thereafter use the shifted
image for the interpolation of the reference image in the digital
camera 1.
[0058] Moreover, if the digital camera 1 suffers a hand shake at
a speed higher than a specified speed, then the actual amount of
shift of the shifted image largely differs from the amount of shift
of the image capturing element 6 by the hand shake correction device
7. If the reference image is corrected by such a shifted image,
then the image becomes rather indistinct. Therefore, when the shake
detection section 11 detects a speed higher than a prescribed speed,
it is proper to carry out no pixel shift with an error indication
displayed on the display device even when the digital camera 1 is
set so as to carry out the pixel shift.
[0059] Although the present invention has been fully described
by way of examples with reference to the accompanying drawings,
it is to be noted 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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