JP2004096673A - Drive mechanism for pixel sliding, and driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize miniaturization of a drive mechanism for pixel shifting. <P>SOLUTION: In a space surrounded by the outermost peripheral part including a region 1A, and by a region 1B inside the region 1A, a piezoelectric element 4 is arranged, in such a manner that one and the other of two facing surfaces perpendicular to a driving direction are fixed with the regions 1A, 1B, respectively. The regions 1A and 1B are linked with each other, by using metal sections 1C at four parts which are symmetrical with a driven shaft AX passing a center of the two facing surfaces of the piezoelectric element 4, thin in the direction of the driven shaft AX and thick in a direction perpendicular to the driven shaft AX. The one and the other of the two facing surfaces of the piezoelectric element 4 are positioned on the sides which are opposite to each other to a center line CL, which is perpendicular to the driven shaft AX and is isolated at equal distance from the two metal sections 1C, which are positioned on the same side of the driven shaft AX. At least a pair of holes 2, 3 for fixing against the outside are arranged respectively on both sides of the center line CL in the region 1A and both sides of the driven shaft AX in the region 1B, thereby constituting the drive mechanism. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving mechanism and a driving device of an image sensor for performing pixel shift.
[0002]
[Prior art]
As a method of increasing the resolution (resolution) of an image sensor in a video camera, an electronic still camera, or the like, there is a method called “pixel shift”. Hereinafter, the resolution of the image sensor will be described, a pixel shifting method will be described, and then a driving mechanism and a driving device that have been conventionally proposed for pixel shifting will be described.
[0003]
[1. Image sensor resolution)
In an image sensor, generally, as shown in FIG. 1, a plurality of pixels P are discretely arranged in a horizontal direction (horizontal direction in the figure) and a vertical direction (vertical direction in the figure). Px and Py are the pixel pitches in the horizontal and vertical directions, respectively.
[0004]
As shown in FIG. 2, assuming that a subject 51 of a vertical stripe (a combination of a black line (hatched portion in the figure) and a white line) with a pitch Ox is imaged by this image sensor, an optical system (lens) 52 in the camera is used. , A vertical stripe image 53 having a pitch lx is projected on the image sensor.
[0005]
At this time, as shown in FIG. 3, if the pitch lx of the vertical stripe image 53 is twice the pixel pitch Px in the horizontal direction, the light from the adjacent black line (hatched portion in the figure) and the white line of the vertical stripe are respectively Since the image is projected on the pixels P adjacent in the horizontal direction, the subject 51 can be imaged in a state where the adjacent black line and white line can be identified. On the other hand, if the pitch lx is less than twice the pixel pitch Px, the subject 51 cannot be imaged in a state where adjacent black lines and white lines can be identified.
[0006]
Therefore, when a vertical stripe image whose pitch lx is twice as large as the pixel pitch Px is projected, the resolution of the image sensor in the horizontal direction is the limit. At this time, as shown in FIG. 4, the image sensor outputs a signal that alternates between a high level and a low level in synchronization with the horizontal transfer clock (period τph).
[0007]
In the field of television, the horizontal resolution of an image sensor is defined by the following equation (1).
RPh = Kh × Nh (1)
Here, RPh is the resolution in the horizontal direction, Kh is the aspect ratio of the imaging surface of the image sensor (for example, 0.75 for 3 to 4), and Nh is the number of pixels in the horizontal direction of the image sensor.
[0008]
At the limit of the resolution in the horizontal direction, a vertical stripe image having a pitch lx twice as large as the pixel pitch Px is projected on the image sensor as shown in FIG. In the case of one stripe, a combination of one black line and one white line) is projected on the image sensor. Therefore, Expression (1) can also be expressed as Expression (2) below using the number of stripes.
RPh = Kh × Noh (2)
Here, Noh is twice the maximum number of stripes of the vertical stripe image projected on the image sensor.
[0009]
2 to 4 show the horizontal direction, but also in the vertical direction, assuming that the image of the horizontal stripe object 54 having the pitch Oy as shown in FIG. 5 is taken, the pitch of the horizontal stripe image projected on the image sensor becomes The vertical resolution is twice as large as the vertical pixel pitch Py in FIG. 1.
[0010]
This vertical resolution is expressed by the following equations (3) and (4) instead of the above equations (1) and (2).
RPv = Kv × Nv (3)
Here, RPv is the resolution in the vertical direction, Kv = 1, and Nv is the number of pixels in the vertical direction of the image sensor.
[0011]
RPv = Kv × Nov (4)
Here, Nov is twice the maximum number of stripes of the horizontal stripe image projected on the image sensor.
[0012]
[2. Pixel shifting method)
[2-1. Application to normal image sensor)
In the image sensor having the pixel array shown in FIG. 1, at a certain timing, each pixel P is positioned at a position indicated by a solid line as shown in FIG. The same object is imaged while alternately repeating the state of being positioned at the broken line shifted by Px / 2. Specifically, in the case of shooting a television image, for example, each pixel P is positioned at a position indicated by a solid line in an odd-numbered frame, and each pixel P is positioned at a position indicated by a broken line in an even-numbered frame.
[0013]
Then, the output signal of the image sensor when each pixel P is positioned at the position indicated by the solid line and the output signal of the image sensor when each pixel P is positioned at the position indicated by the broken line are synthesized.
[0014]
Assuming that a vertical stripe object 51 having a pitch Ox shown in FIG. 2 is imaged by this method, the pitch lx of the vertical stripe image 53 projected on the image sensor is equal to the horizontal pixel shift amount Px as shown in FIG. If it is twice (ie, the same as the pixel pitch Px), the light from the adjacent black line (hatched portion in the figure) and the white line of the vertical stripe are projected onto the pixel P adjacent in the horizontal direction. Therefore, the subject 51 can be imaged in a state where adjacent black lines and white lines can be identified.
[0015]
At this time, the pixel pitch is equal to Px / 2, which is １ ／, and the horizontal resolution of the image sensor is doubled as is apparent from comparison with FIG.
[0016]
Also, at this time, the number of pixels in the horizontal direction is equivalent to doubling, so that the period of the horizontal transfer clock shown in FIG. 4 is equivalent to τph / 2. From the definition in John's field (Equation (1)), the horizontal resolution is expressed as in the following Equation (5).
RPh = Kh × 2Nh (5)
[0017]
Here, an example is described in which each pixel P is shifted by Px / 2 which is １ ／ of the pixel pitch Px, but each pixel P is shifted by 1 / Mh (Mh is an integer) of the pixel pitch Px in the horizontal direction. In the case where images are sequentially taken at different locations, the resolution in the horizontal direction is expressed by the following expression (6) according to the definition in the television field described above.
RPh = Kh × Nh × Mh (6)
[0018]
Although the horizontal direction has been described here, also in the vertical direction, when each pixel P is sequentially positioned at a position shifted by 1 / Mv (Mv is an integer) of the pixel pitch Py in the vertical direction, an image is taken. From the definition in the television field described above (Equation (3)), the resolution in the vertical direction is expressed by the following Equation (7).
RPv = Kv × Nv × Mv (7)
[0019]
[2-2.1 Application to chip color image sensor]
This pixel shifting method can also be applied to a one-chip color image sensor that is an image sensor in which color filters are arranged on pixels. For example, in a one-chip color image sensor in which RGB color filters are arranged as shown in FIG. 8, focusing only on the green pixels, as shown in FIG. 9, the pixel pitches in the horizontal and vertical directions are respectively as shown in FIG. Although Px and Py are the same as the pixel pitch of the image sensor, the pixel pitch in the oblique direction is 2Ps, which is twice the pixel pitch Ps of the image sensor of FIG. Therefore, as it is, the resolution of the green in the oblique direction is １ ／ of the resolution in the oblique direction of the image sensor of FIG.
[0020]
Therefore, with this one-chip color image sensor, pixel shift is performed by taking the amount of pixel shift by Px in the horizontal direction. Then, for the green pixel, as shown in FIG. 10, the state of being located at the position of the solid line and the state of being located at the position of the broken line horizontally shifted by Px from the position of the solid line are alternately repeated. Become.
[0021]
At this time, the pixel pitch of the green pixel in the oblique direction is equal to 1/2 Ps, and the resolution of the green pixel in the oblique direction is double (the oblique resolution of the image sensor of FIG. 1). And the same).
[0022]
The above-mentioned [2-1. Application to Normal Image Sensors] to increase the resolution in the horizontal and vertical directions (for example, in the one-chip color image sensor shown in FIG. 8, the horizontal and vertical resolutions of the red and blue pixels). It is of course possible to increase the resolution in the direction).
[0023]
[3. Conventional drive mechanism and drive for pixel shifting]
As means for periodically changing the position of the image sensor in order to perform the above-described pixel shift, some means have been conventionally proposed. However, Japanese Patent Application Laid-Open No. 1-123580 discloses a means shown in FIG. Such a driving device using a piezoelectric element is disclosed. The main components of this driving device are a horizontal minute displacement plate 150, a vertical minute displacement plate 151, and a CCD board mounting bracket 169, which are the minimum unit driving mechanisms.
[0024]
The horizontal minute displacement plate 150 and the vertical minute displacement plate 151 have the same structure as each other, and are fixed (150a, 151a) and movable (150m, 151m) connected by spring-like metal pieces (150s, 151s). ) Are relatively displaced by piezoelectric actuators (piezoelectric elements) (152, 153). The CCD board mounting bracket 169 fixes the CCD board 101a (a board on which the CCD 101 is fixed and a wiring pattern is formed).
[0025]
The fixing portion 151a of the vertical minute displacement plate 151 is fixed to a mounting plate 172 fixed to the lens mount 167. The fixed portion 150a of the horizontal minute displacement plate 150 is attached to the movable portion 151m of the vertical minute displacement plate 151 such that the direction of relative displacement between the fixed portion and the movable portion is orthogonal to the vertical minute displacement plate 151. Fixed. The CCD board mounting bracket 169 is fixed to the movable part 150m of the horizontal minute displacement plate 150.
[0026]
When a voltage synchronized with the field signal is supplied to the piezoelectric actuators 152 and 153, the movable portion 151m of the vertical-direction minute displacement plate 151 is displaced, so that the entire horizontal-direction minute displacement plate 150 is fixed to the CCD substrate mounting bracket 169. The position of the CCD 101 is periodically displaced with respect to the lens mount 167, and the movable portion 150m of the horizontal minute displacement plate 150 (the position of the CCD 101) is periodically displaced in a direction orthogonal to the position. As a result, pixel shifting in the horizontal and vertical directions is performed.
[0027]
[Problems to be solved by the invention]
By the way, the size of a video camera or an electronic still camera has recently been reduced in size, and accordingly, a driving device for an image sensor for performing pixel shift has also been required to be reduced in size.
[0028]
In order to reduce the size of the image sensor driving device, it is necessary to consider the following points (a) and (b).
(A) Miniaturization of the drive mechanism.
(B) Downsizing of the image sensor holding mechanism.
[0029]
Further, in order to realize the miniaturization of the camera body provided with this driving device, it is necessary to consider the following point (c).
(C) A circuit that electrically connects to the image sensor while the image sensor is mounted on the driving device (held by the holding mechanism) (a circuit that supplies power, a circuit that supplies driving pulses, and an output signal of the image sensor). Processing circuit) to save installation space.
[0030]
However, the conventional driving device disclosed in the above publication has a limitation in miniaturization from any of the points (a) to (c) as described below.
[0031]
[About point (a)]
In order to reduce the size of the driving mechanism (horizontal minute displacement plate, vertical minute displacement plate), the positional relationship between the two regions (fixed portion and movable portion) and the piezoelectric element that are relatively displaced is important. However, there is no description in the above-mentioned publication that takes this arrangement relationship into consideration. As shown in FIG. 19, the piezoelectric actuators 152 and 153 are respectively located at the ends of the driving mechanism (in the horizontal minute displacement plate 150, the fixed portion 150a which is the outer region of the fixed portion 150a and the movable portion 150m). (The end of the movable portion 151m, which is the outer region of the fixed portion 151a and the movable portion 151m in the vertical minute displacement plate 151), the size of the fixed portion 150a and the movable portion 151m. (Area) must be increased, which results in an increase in the size of the drive mechanism (increase in area).
[0032]
[About point (b)]
The CCD board mounting bracket 169 does not directly hold the CCD 101 itself, but holds the CCD board 101a having a considerably larger area than the CCD 101 as shown in FIG. Therefore, the size of the CCD board mounting bracket 169 is increased (the area is increased).
[0033]
In view of the points (a) and (b), the driving device disclosed in the above publication has a considerably large shape with respect to the area of the CCD 101 as shown in FIG. Had limitations.
[0034]
[About point (c)]
Although the above-mentioned publication describes that a wiring pattern is formed on the CCD substrate 101a, there is no description as to where a circuit electrically connected to the CCD 101 is connected to this wiring pattern and disposed. Also, from the shape of the driving device shown in FIG. 19, this circuit cannot be arranged inside the driving device, and this circuit must be arranged on the side of the driving device.
[0035]
For this reason, the combined width of the driving device and the circuit on the side thereof is further increased with respect to the area of the CCD 101. From this point (c), the size of the camera body provided with the driving device can be reduced. There was a limit.
[0036]
In view of the above, the present invention reduces the size of a driving device for pixel shift using a piezoelectric element, and furthermore, electrically connects a camera body provided with the driving device to an image sensor mounted on the driving device. Another object of the present invention is to make it possible to reduce the size of an installation space of a circuit to be connected to a computer.
[0037]
[Means for Solving the Problems]
In order to solve this problem, the present applicant firstly proposes, in a pixel shifting drive mechanism using a piezoelectric element, the relative positions of two relatively displaced regions and the piezoelectric element, which are not considered in the above publication. By clarifying the above, the miniaturization of the drive mechanism (point (a) above) was achieved.
[0038]
That is, in a space surrounded by a first region including the outermost peripheral portion and a second region inside the first region, the piezoelectric element is provided with one of two opposing surfaces orthogonal to the driving direction. , The other surface is fixed to the first region and the second region, respectively, and the first region and the second region are defined by the centers of the two opposing surfaces of the piezoelectric element. One of the two opposing surfaces of the piezoelectric element is connected to each other by four metal portions which are symmetrical with respect to the drive shaft passing therethrough and thin in the direction of the drive shaft and thick in the direction perpendicular to the drive shaft. , The other surface is opposite to a center line which is perpendicular to the drive shaft and is equidistant from two metal portions of the four metal portions on the same side with respect to the drive shaft. Located on either side of the center line in the first region and in the second region At least one pair of holes and / or protrusions for fixing the drive mechanism to the outside are provided on both sides of the drive shaft in the drive shaft. And the second region are relatively displaced in the direction of the drive shaft.
[0039]
In this drive mechanism, when a voltage that changes periodically is supplied to the piezoelectric element, the piezoelectric element is periodically driven so that each connecting portion periodically repeats bending and restoring. The second region periodically repeats the relative displacement in the direction of the drive shaft.
[0040]
Therefore, by fixing one of the first area and the second area to the image sensor through the hole and / or the protrusion, it is possible to perform the pixel shift of the image sensor in the drive axis direction. it can.
[0041]
The period and amount of the pixel shift (the period and amount of relative displacement between the first region and the second region) can be easily and accurately adjusted by adjusting the period and level of the voltage supplied to the piezoelectric element. Can be controlled.
[0042]
In addition, this drive mechanism is downsized from the following points. That is, first, one surface and the other surface of the two fixed surfaces of the piezoelectric element are equidistant from two connection portions orthogonal to the drive shaft and on the same side of the drive shaft among the four connection portions. Are located on opposite sides of a center line at As a result, the piezoelectric element is accommodated in the central portion of the driving mechanism (the central portion of the first region including the outermost peripheral portion), so that the area of the driving mechanism is large as in the conventional driving device disclosed in the above publication. Therefore, the drive mechanism can be downsized (a drive mechanism having a small area).
[0043]
Further, in this drive mechanism, holes and / or protrusions are provided on both sides of the center line in the first region, whereas holes and / or protrusions are provided on both sides of the drive shaft in the second region. Have been. In this manner, both the first region and the second region of the small drive mechanism can be fixed to the outside.
[0044]
In this way, this driving mechanism can perform pixel shift of the image sensor with a small configuration, and can easily perform high-precision control of the cycle and amount of pixel shift.
[0045]
Next, the present applicant, in a pixel shift driving device using a piezoelectric element, reduced the size of the driving mechanism (point (a) described above) and the size of the holding mechanism of the image sensor, which had not been studied before. By examining (point (b) above), the drive device was downsized.
[0046]
This is because the driving mechanism according to the present invention described above (however, the distance of the hole and / or the protrusion in the first region from the intersection of the driving shaft and the center line, the hole in the second region from this intersection, and the like) And / or the distances of the projections are equal to each other) are used one by one as a driving mechanism for horizontal driving and a driving mechanism for vertical driving, and the first area and the second area of the driving mechanism for horizontal driving are used one by one. And one of the first region and the second region of the vertical drive mechanism, which is different from the one region, is formed via the hole and / or the protrusion, and An area different from the one of the first area and the second area of the horizontal drive mechanism and the one of the first area and the second area of the vertical drive mechanism. The areas are fixed to each other so that they do not touch A holder for holding the sensor is different from one of the first area and the second area of the horizontal drive mechanism, and a first area and a second area of the vertical drive mechanism. Are fixed to any one of these areas through the holes and / or protrusions described above.
[0047]
In this drive device, one of the first area and the second area of the horizontal drive mechanism and the one of the first area and the second area of the vertical drive mechanism are provided. Since the region different from the region is fixed to each other, the driving direction of the piezoelectric element of the horizontal drive mechanism is orthogonal to the drive direction of the piezoelectric element of the vertical drive mechanism.
[0048]
The image sensor is held in the holder of this drive unit, and the drive mechanism that is not fixed to the holder, of the drive mechanism for horizontal drive and the drive mechanism for vertical drive, is fixed to the reference position of the camera where the image sensor is installed. In this state, when a voltage that periodically changes is supplied to the piezoelectric element of the horizontal drive mechanism and the piezoelectric element of the vertical drive mechanism, the drive direction of the piezoelectric element of the horizontal drive mechanism and the vertical drive mechanism Since the image sensor is periodically displaced in both directions (directions orthogonal to each other) of the piezoelectric element, the pixels of the image sensor can be shifted in both the horizontal arrangement direction and the vertical arrangement direction of the pixels.
[0049]
As described above, this driving mechanism (driving mechanism for horizontal driving and driving mechanism for vertical driving) can perform the pixel shift of the image sensor with a small (small area) configuration, and the period and amount of the pixel shift. Can be easily controlled with high accuracy. Further, this holder does not hold the CCD substrate 101a having a considerably larger area than the image sensor (CCD 101) like the CCD substrate mounting bracket 169 of the driving device disclosed in the above publication, but directly holds the image sensor itself. Is what you do. Therefore, it is sufficient to have a slightly larger area than the image sensor, so that the size can be reduced.
[0050]
Therefore, the driving device including the driving mechanism for horizontal driving, the driving mechanism for vertical driving, and the holder has a considerably large width with respect to the area of the image sensor (CCD 101) like the driving device disclosed in the above publication. That is, the shape becomes an elongated shape that is not too thick with respect to the area of the image sensor. As a result, the pixel shift of the small-sized image sensor can be performed in both the horizontal arrangement direction and the vertical arrangement direction of the pixels, and the period and amount of the pixel shift can be easily controlled with high accuracy.
[0051]
Furthermore, the applicant of the present invention has realized that in the pixel shift driving device according to the present invention, it is possible to save the installation space of a circuit electrically connected to the image sensor held by the holder (the above point (c)). By studying, the size of the camera body provided with this drive device was reduced.
[0052]
It has an area for holding the image sensor at the top, an area for fixing the holder to the drive mechanism at the bottom, and an opening for making an electrical connection of the image sensor. A structure having a region on a side portion and further having a space between the upper region and the lower region for accommodating a circuit electrically connected to the image sensor.
[0053]
As described above, since the opening area for making the electrical connection of the image sensor exists on the side of the holder (that is, by opening the mouth in a direction orthogonal to the direction in which the holder and each driving mechanism are fixed), this opening area is formed. The electrical connection of the image sensor mounted on the driving device can be easily performed.
[0054]
And, by providing the circuit storage space in the holder itself in this way, unlike the case where the circuit is arranged on the side of the drive device as in the drive device disclosed in the above publication, the installation space of the circuit is saved, The combined width of the driving device and the circuit can also maintain an elongated shape. Therefore, also in this respect, the camera body provided with the driving device can be downsized.
[0055]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be specifically described with reference to the drawings.
[0056]
FIG. 11 is a plan view showing a configuration of an actuator (drive mechanism) for pixel shift according to the present invention. The actuator 1 has a diameter and a thickness of 22 mm and 5.8 mm, respectively, formed by processing a flat cylindrical metal piece, and has an annular region (outer peripheral region) 1A including the outermost peripheral portion. And a U-shaped region (inner peripheral region) 1B inside the outer peripheral region 1A, there is a rectangular parallelepiped space including the center of the actuator 1 (the center of the outermost circle of the outer peripheral region 1A). I have.
[0057]
In this space, a rectangular parallelepiped piezoelectric element 4 is bonded to one of two opposing surfaces (left end surface and right end surface in the figure) orthogonal to the driving direction (longitudinal direction of the rectangular solid) and the other surface, respectively. It is provided by fixing to the outer peripheral area 1A and the inner peripheral area 1B with an agent.
[0058]
The position of the piezoelectric element 4 in this space is determined so that the drive axis AX connecting the centers of the two fixed surfaces (the two opposite surfaces) of the piezoelectric element 4 passes through the center of the actuator 1. As shown in the figure, one surface and the other surface of the two fixed surfaces of the piezoelectric element 4 are perpendicular to the drive axis AX and with respect to a center line CL which is a line passing through the center of the actuator 1. They are located on opposite sides of each other.
[0059]
The width of this space (vertical dimension in the figure) is larger than the width of the piezoelectric element 4, and the side surface (longitudinal surface) of the piezoelectric element 4 is in contact with the outer peripheral area 1 </ b> A and the inner peripheral area 1 </ b> B. I haven't.
[0060]
FIG. 12 is a perspective view showing the shape of the piezoelectric element 4. The thickness H of the piezoelectric element 4 is smaller than the thickness of the above-described metal piece. An electrode 5 for supplying a voltage is connected to the piezoelectric element 4.
[0061]
As shown in FIG. 11, the electrode 5 extends to the side of the actuator 1 through holes (not shown) formed in the side surface of the inner peripheral region 1B and the side surface of the outer peripheral region 1A.
[0062]
The outer peripheral region 1A and the inner peripheral region 1B are connected to each other at four connection portions 1C symmetrical with respect to the drive axis AX of the piezoelectric element 4 (in the figure, the connection portion 1C of the metal piece is (Diagonally shaded for clarity.)
[0063]
Of these connection parts 1C, two connection parts 1C on the same side with respect to the drive shaft AX are mutually at the same distance from the center line CL.
[0064]
Each metal part 1C has a leaf spring shape that is thin in the direction of the drive axis AX and thick in the direction perpendicular to the drive axis AX. When the piezoelectric element 4 is driven, the metal part 1C is bent by the drive pressure and at the bending position. It has a return pressure weaker than the drive pressure, and when the drive pressure disappears thereafter, it is quickly restored to the original position by the return pressure.
[0065]
At both sides of the center line CL in the outer peripheral region 1A and at a position symmetrical with respect to the intersection of the center line CL and the drive axis AX (that is, the center of the cylinder), a pair of members for fixing the actuator 1 to the outside is provided. Hole 2 is formed.
[0066]
Further, a pair of holes 3 for fixing the actuator 1 to the outside are provided at both sides of the center line CL in the inner peripheral region 1B and at positions symmetrical with respect to the intersection of the center line CL and the drive axis AX. Is formed.
[0067]
The holes 2 and 3 are located at the same distance from the intersection of the center line CL and the drive shaft AX, and have the same inner diameter.
[0068]
The operation of the actuator 1 is as follows. When a voltage that changes periodically is supplied to the piezoelectric element 4 via the electrode 5, the piezoelectric element 4 is periodically driven, so that each connecting portion 1C periodically repeats bending and restoration. And the inner peripheral region 1B periodically repeat relative displacement in the direction of the drive axis AX.
[0069]
Therefore, by fixing one of the outer peripheral area 1A and the inner peripheral area 1B to the image sensor through the hole (hole 2A in the area 1A and hole 3 in the area 1B), the image in the drive axis AX direction is obtained. Pixel shift of the sensor can be performed.
[0070]
The period and amount of the pixel shift (the period and amount of relative displacement between the outer peripheral region 1A and the inner peripheral region 1B) can be easily and accurately adjusted by adjusting the period and level of the voltage supplied to the piezoelectric element 4. Can be controlled.
[0071]
Further, the actuator 1 is downsized from the following points. That is, first, one of the two fixed surfaces of the piezoelectric element 4 and the other surface are orthogonal to the drive shaft AX and two of the four connection portions 1C on the same side with respect to the drive shaft AX. They are located on opposite sides of a center line CL equidistant from the part 1C. Thus, since the piezoelectric element 4 is accommodated in the central portion of the actuator 1 (the central portion of the outer peripheral region 1A), the actuator 1 can be downsized (an actuator having a small area).
[0072]
On the other hand, if the two fixed surfaces are positioned on the same side with respect to the center line CL, the piezoelectric element 4 is positioned closer to the end of the actuator 1 (the end of the outer peripheral area 1A). Therefore, the size of the outer peripheral region 1A (the size of the metal piece itself constituting the actuator 1) must be increased, so that the size of the actuator 1 is increased (the area is increased).
[0073]
Further, in the actuator 1, holes 2 are provided on both sides of the center line CL in the outer peripheral area 1A, whereas holes 3 are provided on both sides of the drive shaft AX in the inner peripheral area 1B. In this way, both the outer peripheral area 1A and the inner peripheral area 1B of the small actuator 1 can be fixed to the outside.
[0074]
On the other hand, if the holes 3 are provided on both sides of the center line CL in the inner peripheral region 1B as in the outer peripheral region 1A, the size of the inner peripheral region 1B in the drive axis AX direction must be increased. Again, the size of the actuator 1 increases.
[0075]
In this manner, the actuator 1 can perform pixel shift of the image sensor with a small configuration, and can easily perform high-accuracy control of the cycle and amount of pixel shift. .
[0076]
Therefore, the actuator 1 is very suitable for use in a video camera or an electronic still camera, in which the number of pixels has been increased and the size of the image sensor has been advanced, for performing pixel shift of an image sensor.
[0077]
Next, FIG. 13 is a perspective view showing components of a driving device for pixel shift according to the present invention. This driving device is configured by using the actuators 1 shown in FIG. 11 one by one for horizontal driving and one for vertical driving, and using the CCD holder 7.
[0078]
An inner peripheral region 1B of the actuator 1 (for horizontal driving) and an outer peripheral region 1A of the actuator 1 (for vertical driving) are provided with a washer 6 (thickness) in the hole 3 of the inner peripheral region 1B and the hole 2 of the outer peripheral region 1A. By passing a screw (not shown) across 0.1 mm), the outer peripheral area 1A of the actuator 1 (for horizontal driving) and the inner peripheral area 1B of the actuator 1 (for vertical driving) do not come into contact with each other. Fixed to each other.
[0079]
By fixing the actuator 1 (for horizontal driving) and the actuator 1 (for vertical driving) in this way, the driving direction (X in the drawing) of the piezoelectric element 4 of the actuator 1 (for horizontal driving) and the actuator 1 (for vertical driving) And the driving direction (Y direction in the drawing) of the piezoelectric element 4 is orthogonal to each other.
[0080]
The CCD holder 7 is a U-shaped CCD having a diameter and a height of 20 mm and 7 mm, respectively, formed by processing a cylindrical metal piece having a diameter substantially equal to the cylindrical metal piece used for the actuator 1. The upper part is an area for directly holding the CCD 8 (image sensor) to be shifted. The size of the CCD 8 is about 12 mm on one side.
[0081]
The lower part of the CCD holder 7 is provided with a pair of holes (not shown) having the same inner diameter as the holes 2 and 3 of the actuator 1 in the same direction as the horizontal arrangement direction of the pixels of the CCD 8 to be held. By forming them at the same interval as described above, an area for fixing to the actuator 1 is formed.
[0082]
Further, an opening area for making an electrical connection between the CCD 8 to be held and the outside is provided on a side portion of the CCD holder 7.
[0083]
The CCD holder 7 is provided with the actuator 1 (for vertical driving) by passing a screw (not shown) with a washer 6 between the hole in the lower region and the hole 3 in the inner peripheral region 1B of the actuator 1 (for vertical driving). Is fixed with respect to the inner peripheral area 1B.
[0084]
By fixing the CCD holder 7 and the actuator 1 (for vertical driving) in this manner, the horizontal arrangement direction and the vertical arrangement direction of the pixels of the CCD 8 held in the CCD holder 7 can be adjusted by the piezoelectric actuator of the actuator 1 (for horizontal driving). The driving direction of the element 4 (X in the figure) coincides with the driving direction of the piezoelectric element 4 of the actuator 1 (for vertical driving) (Y direction in the figure).
[0085]
By fixing the actuator 1 (for horizontal driving), the actuator 1 (for vertical driving), and the CCD holder 7 to each other in this manner, a driving device for shifting pixels is configured. As shown in the figure, the size of this driving device is approximately three actuators 1 stacked, and it has a small and long shape which is not too large with respect to the area of the CCD 8, so that the driving device is also miniaturized. ing.
[0086]
The CCD 8 is mounted on the driving device by being held in an upper region of the CCD holder 7.
[0087]
Although not shown in FIG. 13, the flexible printed board 9 is connected to the CCD 8 held by the CCD holder 7 through an opening area on the side of the CCD holder 7 as shown in FIG. You. The flexible printed board 9 includes a power supply circuit for supplying power to the CCD 8, a drive circuit for supplying a drive pulse to the CCD 8, and a signal processing circuit for processing an output signal of the CCD 8.
[0088]
As described above, the opening area for making the electrical connection of the CCD 8 exists on the side of the CCD holder 7 (that is, the opening is opened in a direction orthogonal to the direction in which the CCD holder 7 and each actuator 1 are fixed). Thus, the electrical connection of the CCD 8 mounted on the driving device can be easily performed.
[0089]
Note that the shape of the CCD holder 7 may be a cylindrical shape having an opening area for electrical connection in the middle of the side surface as shown in FIG. Alternatively, as shown in FIG. 15B, a cylindrical shape having an opening area for electrical connection at the lower end of the side surface may be used.
[0090]
Further, a space for housing a circuit electrically connected to the CCD 8 is provided between an upper area for holding the CCD 8 and the lower area for fixing the CCD 8 to the actuator 1. It may have a structure having a structure (a shape that is raised by the amount of the storage space).
[0091]
FIGS. 17A and 17B each show an example in which the CCD holder 7 has such a structure, and portions common to FIG. 13 are denoted by the same reference numerals. In the example of FIG. 17A, a circuit 10 in which a power supply circuit, a drive circuit, and a signal processing circuit are modularized into one is provided in a storage space of the CCD holder 7 with a substrate common to the CCD 8 (for example, a hard disk that can be fixed to the CCD holder 7). It is mounted on a flex-rigid plate (combination of a rigid part having a rigidity and a flexible part that can be bent). A pair of signal lines 12 for inputting and outputting signals to and from the circuit 10 are connected to the substrate 11 through an opening area on the side of the CCD holder 7. The example of FIG. 17B is an example in which the circuit 10 is divided into two.
[0092]
By providing the circuit storage space in the CCD holder 7 itself, unlike the case where the circuits are arranged beside the pixel shift driving device, the circuit installation space can be saved and the driving device and the circuit can be combined. The slender width can also maintain an elongated shape. Therefore, in this respect, the camera body provided with the pixel shift driving device can be downsized.
[0093]
In addition, since the power supply circuit, the drive circuit, and the signal processing circuit are housed in the housing space in the CCD holder 7 as described above, these circuits can be arranged near the CCD 8, so that the influence of noise is reduced. As a result, the operation accuracy of these circuits also increases.
[0094]
Although a CMOS sensor is widely used as an image sensor in addition to a CCD, FIG. 17C shows a holder for holding a CMOS when a pixel to be shifted is a CMOS (the same structure as the CCD holder 7 in FIG. 13). ) Is provided with a storage space for this circuit. The power supply circuit, drive circuit, and signal processing circuit for CMOS are smaller than those for CCD and can be integrated with CMOS. In this example, the circuit 14 integrated with CMOS 13 is a CMOS. It is located in the storage space of the holder 12. A pair of signal lines 15 for inputting and outputting signals to and from the circuit 14 are connected to the circuit 14 via an opening region on the side of the CMOS holder 12.
[0095]
FIG. 17 shows an example in which all the circuits are stored in the storage space in the holder. However, in the case of the CCD holder 7, since the scale of the circuit for the CCD (particularly the scale of the power supply circuit) is large, If a space for accommodating all the circuits is provided, the size of the CCD holder 7 may be increased.
[0096]
FIG. 18 shows an example of a storage space in the CCD holder 7 for such a case, and portions common to FIGS. 13 and 17 are denoted by the same reference numerals. In this example, the CCD holder 7 has a space for accommodating only the drive circuit 16 and the signal processing circuit 17. These circuits 16 and 17 are mounted on the common substrate 11 with the CCD 8 in the storage space of the CCD holder 7 as in the circuit 10 of FIGS. 17A and 17B.
[0097]
In addition, a power supply circuit 18 is mounted on the substrate 21 in a space below the pixel shift driving device (the rear side (right side in the drawing) of the actuator 1 (for horizontal driving) when viewed from the CCD holder 7). The substrate 11 and the substrate 21 are connected by a flexible printed board 19 through an opening area on the side of the CCD holder 7, and a pair of signal lines 20 for inputting and outputting signals to and from the circuits 16 to 18 are connected to the substrate 21. Connected to.
[0098]
As described above, the storage space for the power supply circuit having a particularly large circuit scale is not provided in the CCD holder 7, and the power supply circuit is arranged in the space below the pixel shift driving device, so that the CCD holder 7 has a large size. In addition, the width of the pixel shift driving device and the power supply circuit can be kept slender.
[0099]
In the examples of FIGS. 17 and 18, signal lines for inputting and outputting signals to and from a circuit electrically connected to the image sensor are provided. For example, by outputting a signal wirelessly from a signal processing circuit, The signal line for outputting a signal may be omitted. Further, a signal line for inputting a signal may be omitted by using a battery which does not require external signal input as a power supply circuit. Thus, the camera body provided with the pixel shift driving device can be made smaller and more excellent in portability.
[0100]
In FIG. 13, an outer peripheral area 1A of the actuator 1 (for horizontal driving) is passed through a screw (not shown) through a hole 2 with a washer 6 therebetween, so that a predetermined reference serving as a reference for a video camera or an electronic still camera having a CCD 8 can be obtained. (A part whose position on a plane orthogonal to the optical axis of the lens is fixed with respect to the camera lens).
[0101]
The operation of this driving device is as follows. A periodically changing voltage is supplied to the piezoelectric element 4 of the actuator 1 (for horizontal driving) and the piezoelectric element 4 of the actuator 1 (for vertical driving).
[0102]
Then, since the outer peripheral area 1A of the actuator 1 (for horizontal driving) is fixed with respect to the reference portion of the camera, the inner peripheral area 1B of the actuator 1 (for horizontal driving) is more driven with respect to the camera. It is periodically displaced in the AX direction (X direction).
[0103]
Since the inner peripheral region 1B of the actuator 1 (for horizontal driving) and the outer peripheral region 1A of the actuator 1 (for vertical driving) are fixed to each other, the actuator 1 (for vertical driving) is also periodically displaced as a whole in the X direction. I do. Since the CCD holder 7 is fixed to the inner peripheral area 1B of the actuator 1 (for vertical driving), the CCD holder 7 is also displaced periodically in the X direction. Thereby, the CCD 8 held in the CCD holder 7 is periodically displaced in the horizontal arrangement direction (X direction) of the pixels.
[0104]
Since the inner peripheral area 1A of the actuator 1 (for vertical driving) is periodically displaced in the direction of the drive axis AX (Y direction), the CCD holder 7 is also displaced periodically in the Y direction. As a result, the CCD 8 is periodically displaced in the vertical arrangement direction (Y direction) of the pixels.
[0105]
In this manner, the pixel shift of the CCD 8 can be performed in both the horizontal arrangement direction and the vertical arrangement direction of the pixels.
[0106]
FIG. 16 shows the result of measuring the amount of displacement (pixel shift amount) in the X direction of the CCD 8 with respect to the change in the level of the voltage supplied to the piezoelectric element 4 of the actuator 1 (for horizontal driving). The result was obtained that the displacement amount changed linearly in proportion to the voltage level (hence, it is easy to control the displacement amount with high accuracy).
[0107]
Although not shown, a measurement result was obtained in which the displacement amount of the CCD 8 in the Y direction also changed linearly in proportion to the level of the voltage supplied to the piezoelectric element 4 of the actuator 1 (for vertical driving). .
[0108]
As described above, this driving device can perform the pixel shift of the image sensor in both the horizontal arrangement direction and the vertical arrangement direction of the pixels with a small configuration, and can control the cycle and amount of the pixel shift with high accuracy. It is easy to do.
[0109]
Further, as described above, the electrical connection of the CCD 8 mounted on the driving device can be easily performed. Also, as shown in FIGS. 17 and 18, by providing a circuit storage space in the CCD holder 7 itself, the circuit installation space can be saved, and the width of the combined drive device and circuit can be kept slender. Therefore, the camera body provided with the driving device can be downsized.
[0110]
In the above example, the outer peripheral area 1A and the inner peripheral area 1B of the actuator 1 are connected to the outside (the CCD holder 7, another actuator 1, and a reference part of the camera) through the holes 2 and 3, respectively. Fixed against. However, as another example, a projection may be provided instead of such a hole, and the outer peripheral region 1A and the inner peripheral region 1B may be fixed to the outside via the projection.
[0111]
In the above example, the actuator 1 has a cylindrical shape (the outer peripheral area 1A is annular). However, the present invention is not limited to this, and the actuator 1 is formed into a shape other than the cylindrical shape by processing a metal piece having a shape other than the cylindrical shape (for example, a flat rectangular parallelepiped metal piece). Do).
[0112]
Further, the present invention is not limited to the above-described example, and it is needless to say that various other configurations can be adopted without departing from the gist of the present invention.
[0113]
【The invention's effect】
As described above, according to the pixel shifting drive mechanism of the present invention, it is possible to perform pixel shifting of an image sensor with a small configuration, and to easily perform high-precision control of the cycle and amount of pixel shifting. The effect that it can be obtained is obtained.
[0114]
Further, according to the pixel shift driving device of the present invention, the pixel shift of the image sensor can be performed in both the horizontal arrangement direction and the vertical arrangement direction with a small configuration, and the period and amount of the pixel shift can be performed. The effect is that high-precision control can be easily performed.
[0115]
Further, according to the pixel shifting driving device according to the present invention, an effect is obtained that an image sensor mounted on the driving device can be easily electrically connected.
[0116]
Further, according to the driving device for pixel shifting according to the present invention, it is possible to save the installation space for a circuit electrically connected to the image sensor mounted on the driving device. The effect that the camera body can be miniaturized can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a discrete pixel structure of an image sensor.
FIG. 2 is a diagram showing a state in which an image sensor captures an image of a vertically striped subject.
FIG. 3 is a diagram illustrating a relationship between a pitch of a vertical stripe image and a pixel pitch in a horizontal direction.
FIG. 4 is a diagram illustrating an output signal of an image sensor.
FIG. 5 is a diagram showing an object having a horizontal stripe.
FIG. 6 is a diagram illustrating an example of horizontal pixel shifting.
FIG. 7 is a diagram illustrating a relationship between a pitch of a vertical stripe image and a pixel shift amount in a horizontal direction.
FIG. 8 is a diagram illustrating a color filter array of a one-chip color image sensor.
FIG. 9 is a diagram showing a pixel pitch of green of the one-chip color image sensor.
FIG. 10 is a diagram showing green pixels of a one-chip color image sensor that has undergone pixel shift.
FIG. 11 is a plan view showing a configuration of a pixel shifting actuator of the present invention.
FIG. 12 is a perspective view showing a shape of a piezoelectric element used for the actuator of FIG.
FIG. 13 is a perspective view illustrating a configuration of a pixel shifting driving device according to the present invention.
14 is a diagram showing a state of electrical connection of the CCD held by the driving device of FIG.
FIG. 15 is a diagram showing a modified example of the shape of the CCD holder of the driving device in FIG.
16 is a diagram showing a measurement result of a displacement amount of a CCD by the driving device of FIG. 13;
FIG. 17 is a diagram showing an example in which a circuit storage space is provided in a holder that holds an image sensor.
FIG. 18 is a diagram illustrating an example in which a circuit storage space is provided in a holder that holds an image sensor.
FIG. 19 is a diagram showing a conventional pixel shift driving device using a piezoelectric element.
[Explanation of symbols]
1 Actuator, 2, 3 holes, 4 piezoelectric element, 5 electrodes, 6 washer, 7 CCD holder, 8 CCD, 9 flexible printed board, 10 modularized circuit, 16 drive circuit, 17 signal processing circuit,
18 Power supply circuit

Claims (3)

In a driving mechanism for shifting pixels of an image sensor,
In a space surrounded by a first region including an outermost peripheral portion and a second region inside the first region, the piezoelectric element is provided with one of two opposing surfaces orthogonal to the driving direction and the other. Are fixed to the first area and the second area, respectively.
The first region and the second region are symmetric with respect to a drive axis passing through the centers of the two opposing surfaces of the piezoelectric element, are thin in the direction of the drive axis, and are perpendicular to the drive axis. It is connected to each other by four thick metal parts,
One surface and the other surface of the two opposing surfaces of the piezoelectric element are, for example, from two metal portions orthogonal to the drive shaft and on the same side with respect to the drive shaft among the four metal portions. Are located on opposite sides of the center line at a distance,
At least one pair of holes and / or protrusions for fixing the drive mechanism to the outside are provided on both sides of the center line in the first area and on both sides of the drive shaft in the second area. Has been
A driving mechanism for shifting a pixel, wherein a voltage is supplied to the piezoelectric element so that the first area and the second area are relatively displaced in a direction of the driving axis. In a driving device for shifting pixels of an image sensor,
In a space surrounded by a first region including an outermost peripheral portion and a second region inside the first region, the piezoelectric element is provided with one of two opposing surfaces orthogonal to the driving direction and the other. Are fixed to the first area and the second area, respectively.
The first region and the second region are symmetric with respect to a drive axis passing through the centers of the two opposing surfaces of the piezoelectric element, are thin in the direction of the drive axis, and are perpendicular to the drive axis. It is connected to each other by four thick metal parts,
One surface and the other surface of the two opposing surfaces of the piezoelectric element are, for example, from two metal portions orthogonal to the drive shaft and on the same side with respect to the drive shaft among the four metal portions. Are located on opposite sides of the center line at a distance,
Positions on both sides of the center line in the first region and symmetrical with respect to the intersection between the center line and the drive shaft, and positions on both sides of the drive shaft in the second region with respect to the intersection Holes and / or protrusions for fixing the driving mechanism to the outside at equal distances from the intersection are provided at at least one pair at each symmetrical position,
By supplying a voltage to the piezoelectric element, a driving mechanism that relatively displaces the first region and the second region in the direction of the driving shaft is provided by a driving mechanism for horizontal driving and a driving mechanism for vertical driving. Are used one by one as drive mechanisms for
One of the first area and the second area of the horizontal drive mechanism and the one of the first and second areas of the vertical drive mechanism. An area different from the area is provided through the hole and / or the projection, and an area different from the one of the first area and the second area of the horizontal drive mechanism is defined as The first region and the one of the second regions of the vertical drive mechanism are fixed to each other so as not to contact with each other;
A holder for holding the image sensor includes a region different from the one of the first region and the second region of the horizontal drive mechanism, and a holder of the vertical drive mechanism. A pixel shift driving device fixed to one of the first region and the one of the second regions via the hole and / or the protrusion. . The pixel shift driving device according to claim 2,
The holder has a region for holding the image sensor at an upper portion, a region for fixing the image sensor to the driving mechanism at a lower portion, and an opening region for making an electrical connection of the image sensor. And a space for accommodating a circuit electrically connected to the image sensor between the upper region and the lower region.

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