JPH11252467A - Image-pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized thin image-pickup device for shifting images. SOLUTION: Between a lens 23 and an image-pickup element 26 of this image-pickup device 20, a space filter 24 provided with plural birefringent plates 33-35 is interposed. At least one of these plates 33-35 is tilted with respect to a reference plane 37 vertical to the optical axis 22 of the lens 23. A birefringent plate driving part 25 rotates the angle of at least one birefingent plate, including the tilted double refraction plate 33 among all the the plates 33-35 by a predetermined reference angle with a reference axis parallel to the optical axis 22 as a center, each time the image pickup element performs photoelectric conversion for generating image signals. As a result, the optical path of light from an object 21 after passing through the space filter 24 is moved parallel to the optical axis 22 each time the image-pickup element performs photoelectric conversion. As a result, the image-pickup device 20 is miniaturized and thinned more than the image-pickup device of the conventional technique which shifts the images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus capable of obtaining an image having a higher resolution than that of an image pickup device.

[0002]

2. Description of the Related Art In recent years, there has been a demand for an imaging device such as an electronic still camera to increase the resolution of an image obtained by the imaging device. As a first method for increasing the resolution of the image, a light receiving area of an image sensor provided in the image sensor, that is, the number of pixels of an image sensor is set to be larger than the number of pixels of a conventional image sensor. Conceivable. However, an image sensor having a large number of pixels tends to be expensive due to poor productivity.

As a second technique for increasing the resolution of the image, it is conceivable to use the conventional image pickup device and perform a so-called image shift. Conventional techniques relating to the image shift are disclosed in Japanese Patent Application Laid-Open Nos. 9-9115 and 3-139990.

FIG. 26 is a diagram showing a configuration of a portion relating to processing of light from a subject of the imaging apparatus 1 disclosed in Japanese Patent Application Laid-Open No. 9-9115. The part includes a lens group 3,
It includes an image sensor 4, an image shift unit 5, and a spatial filter unit 6. The image shift unit 5 and the spatial filter unit 6 are interposed between the lens group 3 and the image sensor 4 in this order. The spatial filter unit 6 includes an optical low-pass filter
And an optical low-pass filter rotation mechanism 8. The image shift means includes a parallel flat glass 9 and a parallel flat glass driving unit 10. The parallel plate glass 9 and the optical low-pass filter 7 are arranged in this order on the optical axis 11 of the lens group 3. The parallel flat glass 9 has two central axes orthogonal to the optical axis 11 and orthogonal to each other. The parallel flat glass driving section 10 angularly displaces the parallel flat glass 9 around the two central axes. Thereby, the optical path of the light from the subject is changed to the optical axis 11.
Is translated.

In the above-described image pickup apparatus 1, the parallel flat glass 9
And the optical low-pass filter 7 are arranged on the optical axis 11, respectively.
The length in the direction parallel to is likely to be long. As a result, it becomes difficult to reduce the size of the imaging device 1. Further, since the image shift unit 5 and the spatial filter unit 6 are provided separately,
The number of components is increased as compared with a conventional imaging device that does not perform image shift. As a result, the manufacturing cost of the imaging device 1 tends to increase.

[0006] The configuration of a portion relating to processing of light from a subject of the imaging apparatus disclosed in Japanese Patent Application Laid-Open No. 3-139990 is as follows. The part includes a photographing lens, an image sensor, and a rotation filter. The rotary filter is a colorless, transparent and thick parallel plate, and has a refractive index different from that of air. The rotation filter is interposed between the imaging lens and the image sensor, and is angularly displaced about a predetermined rotation axis. The rotation axis is perpendicular to the imaging surface of the imaging device and intersects the plane of the rotation filter at an angle of less than 90 degrees. As a result, with the angular displacement of the rotary filter, the optical path of the light from the subject is translated from the optical axis of the taking lens.

[0007]

Problems to be Solved by the Invention
The imaging device of Japanese Patent Publication No. 0 does not include a spatial filter. When a spatial filter is added to the image pickup device, it is difficult to reduce the size of the image pickup device and the number of components of the image pickup device is likely to increase as in the case of the image pickup device 1 of JP-A-9-9115. Also, with the angular displacement of the rotary filter, it is expected that the spatial frequency characteristics of the rotary filter may change, but since the rotary filter does not consider changes in the spatial frequency characteristics,
Possibility of maintaining an optimal spatial frequency characteristic for the imaging device regardless of the angular displacement of the rotary filter is poor.

An object of the present invention is to provide an image pickup apparatus for picking up an image having a higher resolution than a conventional image pickup apparatus, and to maintain a spatial frequency characteristic corresponding to the high resolution image even when performing an image shift. It is an object of the present invention to provide an imaging device which can be made smaller and thinner and can reduce assembly costs.

[0009]

SUMMARY OF THE INVENTION The present invention provides an optical system for condensing light from a subject, an image pickup device having an image plane on which the light condensed by the optical system is formed, A spatial filter including at least one birefringent plate interposed between the system and the image sensor, and all the birefringence in the spatial filter to shift an optical path of light incident on the image sensor. Image shifting means for changing the positional relationship between at least one of the birefringent plates and the optical axis of the optical system; and each time the image shifting means changes the positional relationship, an image is provided on the image sensor. An imaging apparatus comprising: an imaging control unit configured to generate an image signal representing the image signal; and a combining unit configured to combine a plurality of the image signals.

According to the present invention, the image pickup apparatus obtains a so-called image shift effect by operating a part of the spatial filter and the image shift means as described above. Thereby, in the portion of the optical path of the light from the subject between the optical system and the image sensor, only all the birefringent plates in the spatial filter are interposed, and the portion is conventionally interposed. The refraction plate for image shift is omitted. Therefore, the distance between the optical system and the image sensor may be shorter than the distance between the optical system and the image sensor in the conventional imaging apparatus by the refraction plate for image shift. it can. Therefore, the so-called back focus is shorter than that of the prior art imaging device, so that the imaging device of the present invention can be made smaller than the prior art imaging device. In addition, since the image shift refraction plate is removed, the number of components of the image pickup apparatus of the present invention is reduced as compared with the conventional image pickup apparatus. Therefore, the imaging device of the present invention can be made lighter than the imaging device of the related art, and the assembly cost can be reduced.

Further, the present invention is characterized in that a spatial frequency characteristic of the spatial filter before the positional relationship is changed is equal to a spatial frequency characteristic of the spatial filter after the positional relationship is changed. I do.

According to the present invention, the spatial filter of the image pickup apparatus can always maintain a predetermined spatial frequency characteristic regardless of a change in the positional relationship. Therefore, if the predetermined spatial frequency characteristic is set in advance to an appropriate spatial frequency characteristic with respect to the resolution of the image represented by the image signal generated by the imaging device, the imaging element can change the positional relationship. Regardless, the subject can always be imaged through the spatial filter having the appropriate spatial frequency characteristics.

Further, according to the present invention, at least one of the at least one birefringent plate is inclined with respect to a reference plane perpendicular to the optical axis. The at least one birefringent plate is angularly displaced about a reference axis parallel to the optical axis.

According to the present invention, the at least one birefringent plate of the image pickup device is tilted in advance with respect to the reference plane to shift the optical path, and the image shift means operates as described above. I do. Thereby, the positional relationship between the tilted birefringent plate and the optical axis, for example, the angle between the incident surface of the tilted birefringent plate and the optical axis changes, thereby obtaining the effect of the image shift. Can be. Therefore, the configuration of the image shift means is as follows:
This is simpler than the prior art image shifting means in which the refraction plate is angularly displaced about a reference axis perpendicular to the optical axis.
Further, the angle between the inclined birefringent plate and the reference plane can be easily adjusted precisely in the assembling process of the imaging device, and the inclined birefringent plate is rotated around the reference axis. Since only the angular displacement is performed, the positional relationship can be easily changed precisely. Therefore,
The accuracy of the image shift of the imaging device can be improved.

Further, in the present invention, a plurality of rectangular light receiving areas are arranged in a matrix on an image forming surface of the image pickup device, and the birefringent plate which is inclined is provided with the birefringent to be angularly displaced. From the optical path of light passing through the spatial filter before the plate is angularly displaced, the optical path of light passing through the spatial filter after the birefringent plate to be angularly displaced is angularly displaced,
It is inclined so as to be shifted in a direction parallel to the diagonal line of the light receiving area, and the angle formed between the inclined birefringent plate and the reference plane is such that the distance between the two optical paths is parallel to the diagonal line. The distance is set so as to be half of the distance between the two light receiving regions arranged in the direction.

According to the present invention, the angle between the inclined birefringent plate in the imaging device and the reference plane and the direction in which the birefringent plate is inclined are determined as described above.
As a result, the two light paths are shifted from each other in a direction parallel to a diagonal line of the light receiving region by a distance that is a half of a distance between the two light receiving regions. The synthesizing unit generates an image signal generated by the image sensor before the birefringent plate to be angularly displaced is angularly displaced, and an image signal generated by the image sensor after the birefringent plate to be angularly displaced is angularly displaced. The image signal is synthesized. As a result, the resolution of the image represented by the synthesized image signal is higher than the resolution of the image sensor. Therefore, since only two image signals are required to obtain an image having a higher resolution than the resolution of the image sensor, the time required for the image sensor to image a subject can be minimized. The convenience of the device is improved.

Further, according to the present invention, the angle at which the image shift means angularly displaces the birefringent plate to be angularly displaced is:
It is characterized by 180 degrees.

According to the present invention, it is preferable that the image shift means shifts the birefringent plate to be angularly displaced by 180 degrees. The first reason is that when the angle of the angular displacement of the birefringent plate is 180 degrees, the angle formed between the birefringent plate and the reference plane can be minimized. This is because the degradation of the image quality of the image related to the inclination of the image can be minimized. The second reason is as follows. Since the birefringent plate to be angularly displaced is angularly displaced by 180 degrees around the reference axis, the shape of the birefringent plate to be angularly displaced can be point-symmetric with respect to the reference axis. Therefore, the substantially rectangular birefringent plate used in the current imaging device can be used as the spatial filter of the imaging device of the present invention. Therefore, if the angle of the angular displacement of the birefringent plate is 180 degrees, an increase in the manufacturing cost of the imaging device can be suppressed.

Further, in the present invention, when a plurality of birefringent plates of all the birefringent plates to be angularly displaced are inclined with respect to the reference plane, each of the plurality of birefringent plates is connected to the reference birefringent plate. The angle between the plane and the plane is equal to each other.

According to the present invention, in the above case, the angles formed by each of the plurality of birefringent plates and the reference plane are equal to each other. This facilitates angle adjustment of the plurality of birefringent plates to be inclined when assembling the imaging device. Further, as the number of birefringent plates inclined at the same angle increases, the sum of the thicknesses of all the inclined birefringent plates in the direction parallel to the optical axis increases. Thereby, the angle formed between each of the plurality of birefringent plates to be inclined and the reference plane can be reduced as the number of birefringent plates inclined at the same angle increases. Therefore, for example, a decrease in the image quality of the image caused by the aberration can be reduced.

Further, according to the present invention, the spatial frequency characteristic of the spatial filter before the birefringent plate to be angularly displaced is angularly displaced, and the spatial frequency characteristic after the birefringent plate to be angularly displaced is angularly displaced. The spatial frequency characteristics of the spatial filter are equal.

According to the present invention, the spatial filter can always maintain a predetermined spatial frequency characteristic regardless of whether or not the tilted birefringent plate is angularly displaced. Therefore, if the predetermined spatial frequency characteristic is set in advance to an appropriate spatial frequency characteristic with respect to the resolution of the image represented by the image signal generated by the imaging device, the imaging device will have a tilted birefringence. Regardless of whether or not the plate is angularly displaced, the subject can always be imaged through the spatial filter having the appropriate spatial frequency characteristics.

[0023]

FIG. 1 is a block diagram showing the overall configuration of an image pickup apparatus 20 according to a first embodiment of the present invention. The imaging device 20 includes a lens group 23, a first spatial filter 24, a birefringent plate driving unit 25, an imaging device 26, and a control device 2.
7, a memory device 28, and a synthesizing device 29.

The lens group 23 is composed of one or a plurality of lenses and has a single optical axis 22. The first spatial filter 24 is interposed between the lens group 23 and the image sensor 26. The first spatial filter 24 has a predetermined spatial frequency characteristic, and limits a part of the spatial frequency component of the light from the subject 21. The light is collected by the lens group 23, passes through the first spatial filter 24, and forms an image on the imaging surface 41 of the imaging element 26.

The first spatial filter 24 has one birefringent plate or a plurality of birefringent plates sequentially arranged along the optical axis 22. In the present embodiment, the first spatial filter 24 has first to third birefringent plates 33 to 35. First
Each of the third to third birefringent plates 33 to 35 is a flat plate having two parallel surfaces. At least one of the one or more birefringent plates has a reference plane 3 perpendicular to the optical axis.
7 is inclined. In the present embodiment, the first and second birefringent plates 33 and 34 are parallel to the reference plane 37, and the third birefringent plate 35 is configured such that its surface and the reference plane 37 form an inclination angle θ1. In addition, it is inclined.

The birefringent plate driving section 25 is controlled by the control device 27, and controls one or a plurality of birefringent plates including at least one birefringent plate which is inclined out of all the birefringent plates to an optical axis. An angular displacement is made around a reference axis parallel to 22 by a predetermined reference angle. In the present embodiment, the birefringent plate driving unit 25 angularly displaces all of the first to third birefringent plates 33 to 35, the reference axis coincides with the optical axis 22, and the reference angle is 180 degrees. It is. That is, the birefringent plate driving unit 25 performs image shifting for changing the positional relationship between at least one birefringent plate to be angularly displaced in the first spatial filter 24 and the optical axis 22 for image shifting. Part. Further, the birefringent plate to be angularly displaced and the birefringent plate driving section 25 have the same function as the conventional image shift section.

The image pickup device 26 generates an image signal by photoelectrically converting the light focused on the image pickup surface, and stores the image signal in the memory device 28. The image sensor 26 has one of a so-called black-and-white single-plate structure, a so-called three-color plate structure, and a so-called single-plate color structure. In the present embodiment, the image sensor 26 has a Bayer array single-plate color structure. Assuming the explanation.

The control device 27 controls the image pickup device 26 and the birefringent plate driving section 25, and the birefringent plate to be angularly displaced by the birefringent plate driving section 25, that is, the first to third birefringent plates 33.
Each time .about.35 is angularly displaced, the image sensor 26 is caused to perform photoelectric conversion, and the resulting image signal is stored in the memory device 28. Further, the control device 27 controls the image sensor 2 among the plurality of image signals stored in the memory device 28.
6. The two image signals generated successively in
To give. The combining device 29 combines the two image signals. Further, the synthesizing device 29 performs a predetermined interpolation process on a single synthesized image signal obtained as a result of the synthesis to generate an output image signal representing an image having a higher resolution than the resolution of the image sensor 26. The output image signal is stored in the memory device 28 and output to the outside of the imaging device 20. The control device 27 and the synthesizing device 29 are realized by, for example, a microcomputer, and the memory device 28 is realized by, for example, a random access memory.

As described above, the imaging device 2 of the present embodiment
At 0, at least one inclined birefringent plate of all the birefringent plates 33 to 35 in the first spatial filter 24, in this embodiment, the third birefringent plate 35 is used for image shift. Doubles as a refraction plate. Therefore, only the first spatial filter 24 is interposed between the lens group 23 and the imaging element 26, and the refraction plate is not interposed. by this,
Compared to conventional imaging devices that perform image shifting,
The distance between the lens group 23 and the image sensor 6 can be reduced. Therefore, since the back focus of the imaging device 20 is shorter than that of the conventional imaging device, the imaging device 20 can be made smaller and thinner than the conventional imaging device. In addition, the imaging device 20
Since the number of components is smaller than that of the conventional imaging device, the manufacturing cost of the imaging device 20 can be reduced more than that of the conventional imaging device.

FIG. 2 is a front view of the imaging surface 41 of the imaging element 26. The imaging device 26 is realized by a CCD (charge coupled device) image sensor. A plurality of pixels 42, i.e., a plurality of light receiving areas, are spaced apart by a first pitch Px in the horizontal direction x and a second pitch Py in the vertical direction y on the imaging surface 41 of the imaging element 26. After that, they are arranged in a matrix. In FIG. 2, pixels are indicated by rectangles. The horizontal direction x is a direction perpendicular to the paper surface in FIG. 1 and the horizontal direction in FIG.
2 and FIG. 2 are assumed to be in the vertical direction on the paper. Further, a direction parallel to the optical axis 22 may be referred to as a Z direction or an optical axis direction. In the present embodiment, the imaging surface 41
Is assumed to have a so-called Bayer array single-plate collar configuration. In the present embodiment, the first and second pitches Px and Py are assumed to be equal, and the first and second pitches Px and Py are collectively referred to as a pitch P. In a state where the pixels 42 are arranged in a matrix, a group of pixels arranged in parallel in the horizontal direction x is referred to as a row, and a group of pixels arranged in the vertical direction y is referred to as a column.

Each pixel of the image sensor having a general single-chip color structure detects the luminance of any one of the three primary colors of light, and the luminance of the color to be detected by each pixel is Different for each pixel. The Bayer array is one of an array of three types of pixels that respectively detect the luminance of each of the three primary colors of color light, and all the pixels include a pixel that detects red luminance and a pixel that detects blue luminance. This is an array in which pixels are classified into three types, that is, pixels for detecting green pixels, and pixels for detecting the luminance of each color are arranged in units of four pixels in two rows and two columns. In the drawing, red,
Within a rectangle representing pixels for detecting green and blue luminance, "R",
"G" and "B" are described and indicated respectively.

The specific arrangement of the pixels 42R, 42B, and 42G for detecting the luminance of each color in the Bayer array is determined by changing the arrangement of all the pixels arranged in a matrix on the imaging surface 41 of the single-chip color imaging device. A description will be given of an example of an arbitrary pair of adjacent rows 45 and 46. In one row 45 of the pair,
Pixels 42G for detecting green luminance and pixels 42B for detecting blue luminance are alternately arranged. In the other row 46 of the pair of rows, pixels 42R for detecting red luminance and pixels 42G for detecting green luminance are alternately arranged. Also, the pixel 42G for detecting the green luminance in one row 45 and the other row 4
6 and a pixel 42G for detecting the green luminance in the horizontal direction x
Are shifted by the pitch P. On the entire imaging surface 41, rows having the same configuration as the pair of rows 45 and 46 are periodically arranged.

FIG. 3 is a diagram showing the first spatial filter 24 before and after the first to third birefringent plates 33 to 35 are angularly displaced. For the following description, the first to third birefringent plates 33 to
A state of the first spatial filter before the angular displacement of the first spatial filter 35 is a first state, and a state of the first spatial filter after the first to third birefringent plates 33 to 35 are angularly displaced by a predetermined reference angle. Defined as the second state. Further, the optical paths 51 and 52 of the light from the subject 21 before passing through the first spatial filter 24 in the first and second states are both formed on the optical axis 2 of the lens group 23.
Assume that it matches 2. Also, of the two surfaces of the first to third birefringent plates 33 to 35, the surface on the side where the light is incident is referred to as an incident surface.

The first state in the first spatial filter 24 in the first state
Since the incident surfaces of the second and second birefringent plates 33 and 34 are perpendicular to the optical axis 22, even after the first and second birefringent plates 33 and 34 are angularly displaced, the incident surfaces are perpendicular to the optical axis 22. . That is, the angle formed by the entrance surfaces of the first and second birefringent plates 33 and 34 in the first spatial filter 24 in the first state and the optical path 51 is equal to the angle in the first spatial filter 24 in the second state. The angle formed between the entrance surfaces of the first and second birefringent plates 33 and 34 and the optical path 52 is equal.

The third birefringent plate 35 of the first spatial filter 24 in the first state is inclined at an inclination angle θ 1 with respect to the reference plane 37. Therefore, for example, the angle formed between the optical paths 51 and 52 and the incident surface of the third birefringent plate 35 is changed by the optical paths 51 and 52.
When measuring clockwise around the intersection of the incident surface 52 and the incident surface, the angle θa1 formed between the incident surface of the third birefringent plate 35 in the first spatial filter 24 and the optical path 51 in the first state.
Is different from the angle θa2 formed by the light path 52 and the incident surface of the third birefringent plate 35 in the first spatial filter 24 in the second state. The angle θa2 is, for example, an angle obtained by subtracting the angle θa1 from 180 degrees.

As described above, in response to the angular displacement of the inclined birefringent plate, the angle formed between the incident surface of the inclined birefringent plate and the optical path of the light before passing through the first spatial filter 24. Changes, the position of the optical path of the light from the subject 21 after passing through the first spatial filter 24 changes with the change in the angle. An optical path of the light after passing through the first spatial filter 24 in the first state, that is, a first optical path 53;
The optical path of the light after passing through the first spatial filter 24 in the second state, that is, the positional relationship of the second optical path 54 is specifically as follows.

The first optical path 53 extends from the optical axis 22 in a predetermined first direction a1 by a predetermined first distance D1.
It is shifted parallel to the optical axis 22. The second optical path 54 is shifted from the optical axis 22 in a second direction a2 opposite to the first direction a1 by a first distance D1 in parallel with the optical axis 22. First direction a
Since 1 is perpendicular to the optical axis 22, the first and second directions a1 and a2 are both parallel to the reference plane 37.
Further, the second direction a2 forms a predetermined angle φ with the vertical direction y. As a result, the second optical path 54 has a distance D from the first optical path 53 in the second direction a2, which is twice the first distance D1.
3 away.

The distance D3 between the two optical paths 53 and 54
Is determined according to the inclination angle of the inclined birefringent plate of all the birefringent plates to be angularly displaced, and the thickness of the inclined birefringent plate. In consideration of the thickness of the inclined birefringent plate, the inclination angle θ1 of the third birefringent plate 35 is such that the distance D3 is √ (P / √2) times the pitch P described above. And so on. The length corresponds to half the distance between the centers of two pixels 42 arranged in a direction U parallel to the diagonal line of the pixels 42 on the imaging surface 41. Also, a direction from the first optical path 53 to the second optical path 54, that is, a second direction a2
Is determined by the inclination direction of the inclined birefringent plate.
The tilt direction is a direction parallel to the virtual plane including the normal to the surface of the tilted birefringent plate and the optical axis 22, and the tilt direction forms the angle φ with the vertical direction y. The inclination direction of the third birefringent plate 35 is adjusted such that the second direction a2 is the direction U parallel to the diagonal line of the pixel 42 on the imaging surface 41 described above.

FIG. 4 is a diagram showing a specific configuration of the birefringent plate driving section 25. The birefringent plate driving section 25 includes a cylindrical holding member 61, a worm 62, a motor 63, a plurality of rotating rollers 64, and a counter 65.

The holding member 61 is provided with a holding hole 66 penetrating in a direction parallel to the central axis 68 thereof. Holding hole 6
6, a birefringent plate to be angularly displaced in the first spatial filter 24, in the present embodiment, first to third birefringent plates 33 to 35
Is fitted. The birefringent plate driving unit 25 is the imaging device 20
The optical axis 22 passes through the holding hole 66.
The holding member 61 has, for example, a center axis 68 of a circle at the outer peripheral end of the holding member 61 coinciding with the optical axis 22, and can be angularly displaced about the optical axis 22. First to third birefringent plates 3
3 to 35, the first and second birefringent plates 33 and 34 are perpendicular to the optical axis 22 and the third birefringent plate 35 when the birefringent plate driving unit 25 is incorporated into the imaging device 20. Is tilted with respect to the reference plane 37 by the tilt angle θ1, and further, is fitted into the holding member 61 such that the optical axis directions of the first to third birefringent plates maintain the positional relationship described later in the first or second state. It is.

Gear teeth are formed on the outer peripheral portion 67 of the holding member 61, and the holding member 61 is a worm gear, that is, a worm wheel. The gear teeth of the outer peripheral portion 67 are meshed with the worm 62. The worm 62 is attached to a rotating shaft of a motor 63. Multiple rotating rollers 6
4 are at least three and are arranged around the holding member 61. Each of the rotating rollers 64 is meshed with a gear tooth of the outer peripheral portion 67. Thereby, the holding member 6
At least three points on one outer peripheral portion 67 are supported. When the motor 63 is driven, the rotational force of the motor 63 is transmitted to the worm 62, and the holding member 61 is angularly displaced about the optical axis 22 with the rotation of the worm 62. The counter 65 counts the number of rotations of the motor 63, and supplies the counted number of rotations to the control device 27.

The control device 27 determines the relationship between the rotation speed of the motor 63 and the amount of angular displacement of the first to third birefringent plates 33 to 35, that is, for example, the holding member 61 A displacement angle is provided in advance. Based on the relationship and the rotation speed of the motor 63 given from the counter 65, the control device 27 controls the first to third times from the time when the motor 63 starts rotating to the time when the counter 65 counts the rotation speed. The angle at which the birefringent plates 33 to 35 are angularly displaced can be obtained. Therefore, the control device 27
The motor 63 is further driven or stopped based on the obtained angle, and the first to third birefringent plates 33
The angle of ~ 35 can be a desired angle.

As described above, since the birefringent plate driving section 25 has a very simple structure, it is easy to reduce the size. Also,
The birefringent plate driving section 25 having an extremely simple configuration can surely angularly displace the birefringent plate to be angularly displaced by a desired angle. In addition, the birefringent plate to be inclined, in this embodiment, the inclination angle θ1 of the third birefringent plate 35
Is determined when the third birefringent plate 35 is attached to the holding member 61, so that the tilt angle can be precisely adjusted. Further, when the image sensor 26 actually captures an image of a subject, the optical path of the light after passing through the first spatial filter 24 is parallelized as described above only by determining the angle at which the third birefringent plate 35 is angularly displaced. Can be moved. Therefore, even when the birefringent plate driving section 25 having a simple configuration is used, the accuracy of image shift can be improved.

The behavior from when the image pickup device 20 picks up the image of the subject 21 to when it outputs the output image signal will be schematically described below.

The image sensor 26 performs photoelectric conversion twice in a predetermined cycle, and outputs an image signal after each photoelectric conversion. The birefringent plate drive unit 25 includes an image sensor 26
During the first photoelectric conversion, the birefringent plates to be angularly displaced, in this embodiment, the first to third birefringent plates 33 to 35 are fixed, and the first state is maintained in the first spatial filter 24. Add. The first to third birefringent plates 33 to 35 are angularly displaced by the reference angle between the time when the first photoelectric conversion is completed and the time when the second photoelectric conversion is started.
The first spatial filter 24 transitions from the first state to the second state. The spatial frequency characteristic of the first spatial filter 24 in the second state, that is, the spatial frequency characteristic, is equal to the spatial frequency characteristic of the first spatial filter 24 in the first state. The birefringent plate driving unit 25 fixes the first to third birefringent plates 33 to 35 while the image sensor 26 performs the second photoelectric conversion, and
The spatial filter 24 keeps the second state. Further, the first spatial filter 24 may maintain the second state during the first photoelectric conversion, and may maintain the first state during the second photoelectric conversion.

Thus, the optical path of the light that has passed through the lens group 23 and the first spatial filter 24 during the second photoelectric conversion passes through the lens group 23 and the first spatial filter 24 during the first photoelectric conversion. The imaging surface 4
In the direction U parallel to the diagonal line of one pixel 42, the pitch is shifted by a length of √ the pitch P of the arrangement of the pixels 42. For this reason, as shown in FIG. 5, the portion of the subject image formed on the imaging surface 41 that has been formed on each pixel 42 during the first photoelectric conversion is the second photoelectric conversion. During the conversion,
Each image is formed at a position 42a indicated by a dotted rectangle.
In FIG. 5, a reference sign “(n, m)” is further added to a reference sign “42” added to a pixel belonging to n rows and m columns in the matrix of pixels 42. Also, during the first photoelectric conversion, n rows m
The portion imaged on the pixel 42 (n, m) in the column is 2
The reference numeral “42a” added to the position where the image is formed during the second photoelectric conversion is further provided with the reference numeral “(n, m)”. n and m are arbitrary natural numbers, respectively. FIG. 5 shows that the birefringent plate driving unit 25 and the third birefringent plate 35
It can be seen that the shift amount of the image shift performed is half the first pitch Px in the horizontal direction x and half the second pitch Py in the vertical direction y. That is, the shift amount is determined in the direction U parallel to the diagonal line of the pixel 42.
In addition, the length is 1/2 times the pitch P of the pixel array.

As a result, the image sensor 26 outputs two image signals. The image represented by each image signal is configured by arranging the same number of pixels as the pixels 42 on the imaging surface 41 in an array similar to the array of the pixels 42 on the imaging surface 41. The plurality of pixels constituting the image include a plurality of pixels 42 on the imaging surface 41,
One-to-one correspondence. Pixel data indicating the hue, lightness, and the like of each pixel of the image are determined according to the hue, lightness, and the like of a portion of the subject image formed on the pixel 42 corresponding to the pixel. The combining device 29 combines the two image signals generated by the first and second photoelectric conversions to generate a combined image signal. The synthesizing device 29 further performs a predetermined interpolation process on the synthesized image signal. As a result, the output image signal is obtained.

FIG. 6 is a diagram showing a part of an output image obtained by virtually visually displaying the output image signal. Each of the black frame rectangles indicates a pixel of the output image. Among the pixels of the output image, the pixels on which the reference symbol “a (n, m)” is drawn correspond to the pixels in the n-th row and the m-th column of the image represented by the image signal generated by the first photoelectric conversion. , The pixel data of the pixel in the n-th row and the m-th column is applied. Among the pixels of the output image, the pixel on which the reference symbol “b (n, m)” is drawn is 2
The image data represented by the image signal generated by the second photoelectric conversion corresponds to the pixels at n rows and m columns, and the pixel data of the pixels at n rows and m columns is applied. Among the pixels of the output image,
Pixels marked with “○” are virtual pixels that do not correspond to any pixels in the image represented by the two image signals, and pixel data is determined by interpolation processing. As described above, since the second optical path 54 is translated from the first optical path 53 in the direction U parallel to the diagonal line by a length of √ the pitch P, the second optical path 54 is referred to as b ( The pixels marked with (n, m) are inserted between the pixels marked with reference signs a (n, m) and a (n + 1, m + 1). The virtual pixel is
The output images are arranged in a checkered pattern.

As a result, the output image has four times the number of pixels and twice the number of rows and columns of pixels as compared to the image represented by the image signal. As a result, the resolution of the output image in the horizontal direction x and the vertical direction y is twice the resolution of the image sensor 26 in the horizontal direction x and the vertical direction y, respectively. In other words, the optical paths 53 and 54 of the light that has passed through the first spatial filter 24 during the first and second photoelectric conversions have a length that is √ of the pitch P in a direction parallel to the diagonal line of the pixel 42. In the case of shifting only, the positions of the optical paths 53 and 54 are appropriate shift positions for improving the resolution of the output image to be higher than the resolution of the image sensor 26.

In the above case, as described above, the resolution of the output image in both the horizontal direction x and the vertical direction y can be improved by using two image signals. If the shift directions and the shift intervals of the first and second optical paths 53 and 54 are not set as described above, in order to improve both the resolution in the horizontal direction x and the vertical direction y of the output image, three or more It is expected that an image signal will be required. From these facts, the first and second optical paths 53, 5
When the relation of No. 4 is set to the above-described relation, the number of image signals to be generated by the imaging element 26 in order to obtain one output image can be minimized. Therefore, it is possible to minimize the time required for the image sensor 26 to image a subject in order to obtain one output image.
Therefore, the convenience of the imaging device 20 can be improved.

FIGS. 7A to 7C are diagrams showing the optical axis directions q1 to q3 of the first to third birefringent plates 33 to 35 of the first spatial filter 24 in the first state. . The optical axis directions q1 to q3 of the first to third birefringent plates 33 to 35 are respectively cut out at about 45 degrees with respect to the optical axis 22 and have different projection directions. The projection direction is the direction of the projected image when the optical axis directions q1 to q3 are projected on the xy plane, that is, the reference plane 37. Defined as degrees. The projection direction of the first birefringent plate 33 in the optical axis direction q1 is 90 degrees counterclockwise from the horizontal direction x. The projection direction in the optical axis direction q2 of the second birefringent plate 34 is the horizontal direction x
0 degrees clockwise from The projection direction of the third birefringent plate 35 in the optical axis direction q3 is 45 degrees counterclockwise from the horizontal direction x.

The spatial frequency characteristics of the first spatial filter 24 in the first and second states will be described below. The spatial frequency characteristics are determined according to the state of light separation after passing through the first spatial filter 24. Generally, light incident on a single birefringent plate is separated into an ordinary ray and an extraordinary ray while passing through the inside of the birefringent plate, and the ordinary ray is an optical path before incidence of the incident light. The extraordinary ray is translated from the optical path before the incidence by a separation width determined according to the thickness of the birefringent plate in the projection direction in the optical axis direction of the birefringent plate, and is emitted. . The vibrating surface of the ordinary ray is perpendicular to the optical axis direction of the birefringent plate, and the vibrating surface of the extraordinary ray is parallel to the optical axis direction of the birefringent plate. First to third birefringent plates 33 to 3
The thickness of No. 5 is adjusted so that the separation widths d1 to d3 are respectively half of the pitch P (P / 2), half of the pitch P, and √ of the pitch P, respectively. .

FIGS. 8A to 8C show the first to third birefringent plates 33 to 33 in the first spatial filter 24 in the first state.
It is a figure for explaining 35 separation light images.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. While passing through the first birefringent plate 33, the light is separated into an ordinary ray Lo and an extraordinary ray Le and emitted as shown in FIG. First birefringent plate 3
The direction from the ordinary ray Lo of No. 3 to the extraordinary ray Le of the first birefringent plate 33 is equal to the projection direction of the first birefringent plate 33 in the first state in the optical axis direction q1, that is, the vertical direction y. The ordinary ray Lo of the first birefringent plate 33 and the first birefringent plate 33
Is separated from the extraordinary ray Le by a separation width d1.

Next, the ordinary ray Lo and the extraordinary ray Le of the first birefringent plate 33 are incident on the second birefringent plate 34. FIG.
As shown in (B), the ordinary ray Lo of the first birefringent plate 33
Is defined as an extraordinary ray Loe of the second birefringent plate while passing through the second birefringent plate 34 from the original position by a separation width d2.
The second birefringent plate 34 in the first state is emitted while being shifted in the projection direction of the optical axis direction q2, that is, in the horizontal direction x.
The extraordinary ray Le of the first birefringent plate 33 is, as shown in FIG. 8B, an ordinary ray Leo of the second birefringent plate 24.
The light is emitted as it is without changing its position while passing through the second birefringent plate 34. Since the vibration surface of the ordinary ray Lo of the second birefringent plate 33 is parallel to the optical axis direction q2, there is no ordinary ray of the second birefringent plate 34 corresponding to the ordinary ray Lo of the first birefringent plate 33. Since the vibration surface of the extraordinary ray Le of the first birefringent plate 33 is perpendicular to the optical axis direction q2, there is no extraordinary ray of the second birefringent plate 24 corresponding to the extraordinary ray Le of the first birefringent plate 34.

Subsequently, the ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35. While passing through the third birefringent plate 35, the extraordinary ray Loe of the second birefringent plate 34, as shown in FIG.
The ordinary ray Loeo of the birefringent plate 35 and the extraordinary ray Loee of the third birefringent plate are separated and emitted. Second birefringent plate 3
While passing through the third birefringent plate 35, the ordinary ray Leo of No. 4 has an ordinary ray Leoo of the third birefringent plate 35 and an extraordinary ray Leoe of the third birefringent plate as shown in FIG. And emitted. The ordinary ray Loeo of the third birefringent plate 35
The direction from to the extraordinary ray Loee of the third birefringent plate, and the direction from the ordinary ray Leoo of the third birefringent plate 35 to the extraordinary ray Leoe of the third birefringent plate are the third birefringent plate in the first state. The projection direction in the optical axis direction q3 of 35, that is, the direction of 45 degrees counterclockwise from the swimming direction x is equal to each. The ordinary ray Loeo of the third birefringent plate 35 and the third ray
Separated from the extraordinary ray Loee of the birefringent plate by a separation width d3,
Further, the ordinary ray Leoo of the third birefringent plate 35 and the extraordinary ray Leoe of the third birefringent plate are separated by a separation width d3.

Therefore, the separated state of the light finally obtained by the first spatial filter 24 in the first state is the separated state shown in FIG. 8C, that is, the separated state shown in FIG. Specifically, the separated state is determined by the ordinary ray Leoo of the third birefringent plate 35 and the extraordinary ray Loee of the third birefringent plate 35.
Are arranged in parallel with the horizontal direction x at the same interval as the pitch P, and the ordinary ray Loe of the third birefringent plate 35
o and the extraordinary ray Leoe of the third birefringent plate 35 are arranged in parallel with the vertical direction y at the same interval as the pitch P described above.

FIGS. 10A to 10C show the first to third birefringent plates 33 to 35 of the first spatial filter 24 in the second state.
FIG. 3 is a diagram showing projection directions of optical axis directions q1 to q3 of FIG. The projection directions of the optical axis directions q1 to q3 of the first to third birefringent plates 33 to 35 of the first spatial filter 24 in the second state are the first to third of the first spatial filter 24 in the first state. The projection direction of the optical axis directions q1 to q3 of the birefringent plates 33 to 35 is a direction which is displaced by 180 degrees around an axis parallel to the optical axis 22. Specifically, the projection direction of the first birefringent plate 33 in the optical axis direction q1 is 90 degrees clockwise from the horizontal direction x. The projection direction in the optical axis direction q2 of the second birefringent plate 34 is 180 degrees clockwise from the horizontal direction x. The projection direction of the third birefringent plate 35 in the optical axis direction q3 is 135 degrees clockwise from the horizontal direction x.

FIGS. 11A to 11C show the first to third birefringent plates 33 in the first spatial filter 24 in the second state.
It is a figure for demonstrating the separation light image of -35. FIG.
8 is different from FIG. 8 in that the position of the ordinary ray and the position of the extraordinary ray are respectively replaced, and the others are equal. The details will be described below.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. While passing through the first birefringent plate 33, the light, as shown in FIG.
And an extraordinary ray Le. From the ordinary ray Lo of the first birefringent plate 33 to the extraordinary ray Le of the first birefringent plate 33
The direction heading toward is equal to the projection direction of the first birefringent plate 33 in the second state in the optical axis direction q1, that is, the direction of 90 degrees clockwise from the horizontal direction x. The ordinary ray Lo of the first birefringent plate 33 and the extraordinary ray Le of the first birefringent plate 33 are separated by a separation width d1.

Next, the ordinary ray Lo and the extraordinary ray Le of the first birefringent plate 33 enter the second birefringent plate 34. FIG.
1 (B), the ordinary ray Lo of the first birefringent plate 33
Is defined as an extraordinary ray Loe of the second birefringent plate while passing through the second birefringent plate 34 from the original position by a separation width d2.
The second birefringent plate 34 in the second state is emitted in a direction shifted 180 degrees clockwise from the projection direction in the optical axis direction q2, that is, the horizontal direction x. Also, the first birefringent plate 33
As shown in FIG. 11B, the extraordinary ray Le is emitted as the ordinary ray Leo of the second birefringent plate 24 without changing its position even while passing through the second birefringent plate 34. First
Second birefringent plate 34 corresponding to ordinary ray Lo of birefringent plate 33
And the extraordinary ray of the second birefringent plate 24 corresponding to the extraordinary ray Le of the first birefringent plate 34 do not exist for the same reason as in FIG.

Subsequently, the ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35.
As shown in FIG. 11C, the ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 pass through the third birefringent plate 35, while the ordinary rays Leoo and Lo of the third birefringent plate 35 pass.
eo and the extraordinary rays Leoe and Loee of the third birefringent plate are respectively emitted. The ordinary rays Leoo and Loeo of the third birefringent plate 35 and the extraordinary rays Le of the third birefringent plate
oe and Loee are separated from each other by a separation width d3. The direction from the ordinary rays Leoo, Loeo of the third birefringent plate 35 to the extraordinary rays Leoe, Loee of the third birefringent plate 35 is the projection direction in the optical axis direction q3 of the third birefringent plate 35 in the second state. That is, it is equal to a direction of 135 degrees counterclockwise from the horizontal direction x. Therefore, the separated state of the ordinary ray and the extraordinary ray finally obtained in the first spatial filter 24 in the second state is shown in FIG.
The separation state shown in FIG. 9C is obtained, that is, the separation state shown in FIG.

From the above, it can be seen that the separated state of the light finally obtained in the first spatial filter 24 in the first and second states is equal. Therefore, the spatial frequency characteristic of the first spatial filter 24 in the first state is equal to the spatial frequency characteristic of the first spatial filter 24 in the second state. Therefore, the spatial frequency characteristics
If the spatial frequency characteristics suitable for the resolution of the output image are set in advance, the image sensor 26 can image the subject 21 via the first spatial filter 24 having appropriate spatial frequency characteristics. That is, regardless of the fact that at least one birefringent plate in the first spatial filter 24 has been angularly displaced for image shift, the imaging device 26
Can always be imaged through the first spatial filter 24 having appropriate spatial frequency characteristics.

In the first and second states, the first to third birefringent plates 33 to 35 are in the optical axis direction q1 to q3.
If the mutual positional relationship of q3 is as described above, even if the arrangement order is changed, the final separated state will be the state shown in FIG. 9, so that the spatial frequency characteristics are equal to those described above. Therefore, the arrangement order of the first to third birefringent plates 33 to 35 may be changed from the above-described arrangement order. In the above-described imaging device 20, the birefringent plate inclined with respect to the reference plane 37 is one of the birefringent plates that are angularly displaced.
The first or second birefringent plate 33, 34 may be inclined with respect to the reference plane 37 instead of the third birefringent plate 35.

Hereinafter, an imaging apparatus according to a second embodiment of the present invention will be described. The imaging device according to the second embodiment has the first
As compared with the imaging device 20 of the embodiment, only the point that the first spatial filter 24 is replaced by the second spatial filter 81 is different, and the others are equal. In the configuration of the imaging device according to the second embodiment, a description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components configuring the imaging device of the second embodiment, components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

FIG. 12 shows the second spatial filter 8 in the first state.
FIG. 3 is a diagram illustrating a first spatial filter 81 in a second state. In the second spatial filter 81, only the first birefringent plate 33 is parallel to the reference plane 37, and the second and third birefringent plates 3
4 and 35 are inclined at a predetermined inclination angle θ2 with respect to the reference plane 37. The birefringent plate driving unit 25 moves the first to third birefringent plates 33 to 35 of the second spatial filter 81 in the first state, indicated by solid lines, into the optical axis 2 for image shift.
The angular displacement is 180 degrees around the axis parallel to 2. As a result, the second spatial filter 81 enters the second state. Second and third birefringent plates 3 of the spatial filter in the second state
4 and 35 are inclined with respect to the reference plane 37 as shown by the two-dot broken line.

In the second embodiment, the analogous birefringent plate is inferred from the description with reference to FIG. 3. In the second embodiment, the second and third birefringent plates 35 are angularly displaced about the axis. Accordingly, the position of the optical path of the light from the subject 21 after passing through the second spatial filter 81 changes. First
It is assumed that both the optical paths 51 and 52 of the light from the subject 21 before passing through the second spatial filter 81 in the second state coincide with the optical axis 22 of the lens group 23. In this case, the light path 54 of the light after passing through the second spatial filter 81 in the second state becomes the second spatial filter 81 in the first state.
From the optical path 53 of the light after passing, the pixel 42 of the imaging surface 41
The pitch P of the array of pixels 42 in the direction U parallel to the diagonal
The inclination directions of the second and third birefringent plates 34 and 35 and the inclination angles of the second and third birefringent plates 34 and 35 are adjusted so as to be shifted by √ times the length of I have.

The second and third birefringent plates 34 and 35 are, as shown in FIG.
May be spaced between the second and third
The birefringent plates 34 and 35 may be arranged in contact with each other without any gap. Further, for the same reason as described in the first embodiment, the arrangement order of the first to third birefringent plates 33 to 35 may be changed from the above-described arrangement order. The birefringent plate inclined with respect to the reference plane 37 may be any two of the birefringent plates that are angularly displaced. And the second birefringent plates 33, 3
4 may be inclined with respect to the reference plane 37, the first
Further, the third birefringent plates 33 and 35 may be inclined with respect to the reference plane 37.

Hereinafter, an imaging apparatus according to a third embodiment of the present invention will be described. The imaging device according to the third embodiment has the first
As compared with the imaging device 20 of the embodiment, only the point that the first spatial filter 24 is replaced by the third spatial filter 83 is different, and the others are equal. In the configuration of the imaging device according to the third embodiment, description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components constituting the imaging device of the third embodiment, components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

FIG. 13 shows the third spatial filter 8 in the first state.
FIG. 3 is a diagram illustrating a third spatial filter 83 in a second state. The third spatial filter 83 includes the first to third birefringent plates 3.
4 and 35 are inclined with respect to the reference plane 37 at a predetermined inclination angle θ3. The birefringent plate driving unit 25 moves the first to third birefringent plates 33 to 35 of the third spatial filter 83 in the first state, indicated by solid lines, to the optical axis 2 for image shift.
The angular displacement is 180 degrees around the axis parallel to 2. As a result, the third spatial filter 83 is connected to the second spatial filter 83 by the two-dot chain line.
State. The first to third birefringent plates 33 to 35 are shown in FIG.
As shown by, at least one of between the first and second birefringent plates 33 and 34 and between the second and third birefringent plates 34 and 35 may be arranged with a space therebetween. -The third birefringent plates 34 and 35 may be arranged in contact with each other without a gap.

In the third embodiment, the analogous birefringent plate is inferred from the description of FIG. 3, and in the third embodiment, the first to third birefringent plates 33 to 35 are angled around the axis. In accordance with the displacement, the position of the optical path of the light from the subject 21 after passing through the third spatial filter 83 changes. It is assumed that both the optical paths 51 and 52 of the light from the subject 21 before passing through the third spatial filter 83 in the first and second states coincide with the optical axis 22 of the lens group 23. In this case, the light path 54 of the light after passing through the third spatial filter 83 in the second state is connected to the third spatial filter 8 in the first state.
3 from the optical path 53 of the light after passing through
In the direction U parallel to the two diagonals, the first to third pixels are shifted by a length of √ the pitch P of the array of the pixels 42.
Inclination directions of birefringent plates 33 to 35 and first to third birefringent plates 3
The inclination angles θ3 of 3 to 35 are adjusted.

In the first to third embodiments, the optical paths 54 of the light after passing through the first to third spatial filters 24, 81 and 83 in the second state are all the first to third optical filters in the first state. From the optical path 53 of the light after passing through the three spatial filters 24, 81, 83, in the direction U parallel to the diagonal line of the pixel 42,
It is shifted by half the length. Therefore, the inclination angle θ2 of the second and third birefringent plates 34 and 35 of the second spatial filter 81 may be smaller than the inclination angle θ1 of the third filter 35 of the first spatial filter 24. Further, the inclination angle θ of the first to third birefringent plates 33 to 35 of the third spatial filter 83
3 may be smaller than the inclination angles θ1 and θ2.
This is because, as the number of inclined birefringent plates increases, the length of a portion of the optical path of the light that passes through the inside of the inclined birefringent plate increases, so that the length of the optical path shift increases. . In addition, as the angle of inclination of the birefringent plate becomes smaller, light is less likely to be affected by aberration or the like when passing through the spatial filter. , Can be suppressed.

Hereinafter, an imaging apparatus according to a fourth embodiment of the present invention will be described. The imaging device according to the fourth embodiment has a first
As compared with the imaging device 20 of the embodiment, only the point that the first spatial filter 24 is replaced by the fourth spatial filter is different, and the others are equal. In the configuration of the imaging device according to the fourth embodiment, description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components constituting the imaging device of the fourth embodiment, the components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

The fourth spatial filter has first to third birefringent plates 33 to 35, and first and second birefringent plates 33, 33.
At least one of the 34 is inclined with respect to the reference plane 37. That is, the first birefringent plate 33, the second birefringent plate 34, or the first and second birefringent plates 3
Both 3 and 34 are inclined with respect to the reference plane 37. The mutual positional relationship of the first to third birefringent plates 33 to 35 in the optical axis directions q1 to q3 in the fourth spatial filter in the first state is equal to that of the first spatial filter 24 in the first state. The birefringent plate drive unit 25 displaces only the first and second birefringent plates 33 and 34 by 180 degrees. The third birefringent plate 35 is always fixed. For this purpose, for example, the first and second birefringent plates 33,
Only 34 is fitted, and the third birefringent plate 35 is fixed to another holding member. In this case, the fourth state of the second state
The optical path of the light after passing through the spatial filter is shifted from the optical path of the light after passing through the fourth spatial filter in the first state from the imaging surface 4.
In the direction U parallel to the diagonal line of one pixel 42, the pitch is shifted by a half of the pitch P of the array of the pixels 42,
The inclination direction and the inclination angle of the inclined birefringent plate of the first and third birefringent plates 33 and 35 are adjusted.

FIGS. 14A to 14C show the first to third birefringent plates 33 to 35 of the fourth spatial filter in the second state.
FIG. 3 is a diagram showing projection directions of optical axis directions q1 to q3 of FIG. Optical axis direction q1 to q3 of first to third birefringent plates 33 to 35
Are cut out at approximately 45 degrees with respect to the optical axis 22. The projection direction of the first birefringent plate 33 in the optical axis direction q1 is 90 degrees clockwise from the horizontal direction x. The projection direction in the optical axis direction q2 of the second birefringent plate 34 is 180 degrees clockwise from the horizontal direction x. Third birefringent plate 3
The projection direction in the optical axis direction q3 of No. 5 is equal to the direction shown in FIG. 7C, and is 45 degrees counterclockwise from the horizontal direction x.

FIGS. 15A to 15C show the first to third birefringent plates 33 in the fourth spatial filter in the second state.
It is a figure for demonstrating the separation light image of -35. The spatial frequency characteristics of the fourth spatial filter in the second state will be described with reference to FIG.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. First and second birefringent plates 33,
FIG. 15 (A) shows the state of separation of the light while passing through.
As shown in FIG. 15 (B) and FIG. 15 (B), they are the same as the light separation states described in FIG. 11 (A) and FIG.

The ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35. FIG.
As shown in (C), the ordinary ray Leo of the second birefringent plate 34
While passing through the third birefringent plate 35, the extraordinary ray Loe is separated into the ordinary rays Leoo, Loeo of the third birefringent plate 35 and the extraordinary rays Leoe, Loee of the third birefringent plate, and is emitted. I do. Ordinary ray L of the third birefringent plate 35
eoo, Loeo and the extraordinary ray of the third birefringent plate, Leeo,
Loee is separated from Loee by a separation width d3. The direction from the ordinary rays Leoo, Loeo of the third birefringent plate 35 to the extraordinary rays Leoe, Loee of the third birefringent plate is as follows.
The projection direction of the third birefringent plate 35 in the second state in the optical axis direction q3, that is, the direction of 45 degrees counterclockwise from the horizontal direction x is equal to each other.

Accordingly, the separated state of the light finally obtained in the fourth spatial filter in the second state is the separated state shown in FIG. 15C, that is, the separated state shown in FIG. From the above, it can be seen that the light separation states finally obtained in the fourth spatial filter in the first and second states are equal. Therefore, the spatial frequency characteristic of the fourth spatial filter in the first state is equal to the spatial frequency characteristic of the fourth spatial filter in the second state.

Hereinafter, an imaging apparatus according to a fifth embodiment of the present invention will be described. The imaging device according to the fifth embodiment includes the first
As compared with the imaging device 20 of the embodiment, only the point that the first spatial filter 24 is replaced by the fifth spatial filter is different, and the others are equal. In the configuration of the imaging device according to the fifth embodiment, description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components constituting the imaging device of the fifth embodiment, components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

The fifth spatial filter has first to third birefringent plates 33 to 35, and only the third birefringent plate 35 is inclined with respect to the reference plane 37. The positional relationship between the first to third birefringent plates 33 to 35 in the optical axis directions q1 to q3 of the fifth spatial filter in the first state is equal to that of the first spatial filter 24 in the first state. The birefringent plate drive unit 25 displaces only the third birefringent plate 35 by 180 degrees around an axis parallel to the optical axis 22. The first and second birefringent plates 33, 34 are always fixed. For this,
For example, only the third birefringent plate 35 is fitted into the holding member 61, and the first and second birefringent plates 33 and 34 are fixed to another holding member. In this case, the optical path of the light after passing through the fifth spatial filter in the second state is parallel to the diagonal line of the pixel 42 on the imaging surface 41 from the optical path of the light after passing through the fifth spatial filter in the first state. In the direction U, the pixel 42
The inclination direction and the inclination angle of the third birefringent plate 35 are adjusted so as to be displaced by a length of √ the pitch P of the arrangement of the third birefringent plate.

FIGS. 16A to 16C show the first to third birefringent plates 33 to 35 of the fifth spatial filter in the second state.
FIG. 3 is a diagram showing projection directions of optical axis directions q1 to q3 of FIG. Optical axis direction q1 to q3 of first to third birefringent plates 33 to 35
Are cut out at approximately 45 degrees with respect to the optical axis 22. The projection direction in the optical axis direction q1 of the first birefringent plate 33 is equal to the direction shown in FIG. 7A, and is 90 degrees counterclockwise from the horizontal direction x. The projection direction in the optical axis direction q2 of the second birefringent plate 34 is 0 degrees clockwise from the horizontal direction x. The projection direction in the optical axis direction q3 of the third birefringent plate 35 is equal to the direction shown in FIG. 7C, and is 135 degrees clockwise from the horizontal direction x.

FIGS. 17A to 17C show the first to third birefringent plates 33 in the fifth spatial filter in the second state.
It is a figure for demonstrating the separation light image of -35. The spatial frequency characteristics of the fifth spatial filter in the second state will be described with reference to FIG.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. First and second birefringent plates 33,
FIG. 17 (A) shows the state of separation of the light while passing through.
As shown in FIG. 17 (B) and FIG. 17 (B), they are the same as the light separation states described in FIG. 8 (A) and FIG.

The ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35. FIG.
As shown in (C), the ordinary ray Leo of the second birefringent plate 34
While passing through the third birefringent plate 35, the extraordinary ray Loe is separated into the ordinary rays Leoo, Loeo of the third birefringent plate 35 and the extraordinary rays Leoe, Loee of the third birefringent plate, and is emitted. I do. Ordinary ray L of the third birefringent plate 35
eoo, Loeo and the extraordinary ray of the third birefringent plate, Leeo,
Loee is separated by a separation width d3. The direction from the ordinary rays Leoo, Loeo of the third birefringent plate 35 to the extraordinary rays Leoe, Loee of the third birefringent plate is as follows.
The projection direction of the third birefringent plate 35 in the second state in the optical axis direction q3, that is, 135 in the counterclockwise direction from the horizontal direction x.
Equal to the direction of the degree.

Therefore, the separation state of the light beam finally obtained in the fifth spatial filter in the second state is as follows:
The separation state shown in FIG. 17C, that is, the separation state shown in FIG. From the above, it can be seen that the separated state of light finally obtained in the fifth spatial filter in the first and second states is equal. Therefore, the spatial frequency characteristic of the fifth spatial filter in the first state is equal to the spatial frequency characteristic of the fifth spatial filter in the second state.

Hereinafter, an imaging apparatus according to a sixth embodiment of the present invention will be described. The imaging device according to the sixth embodiment includes a first
As compared with the imaging device 20 of the embodiment, only the point that the first spatial filter 24 is replaced by the sixth spatial filter is different, and the others are equal. In the configuration of the imaging device according to the sixth embodiment, description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components configuring the imaging device of the sixth embodiment, components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

The sixth spatial filter has first to third birefringent plates 33 to 35, and the first and third birefringent plates 33, 35.
At least one of the 35 is inclined with respect to the reference plane 37. That is, the first birefringent plate 33 or the third birefringent plate 35 is used alone, or both the first and third birefringent plates 33 and 35 are inclined with respect to the reference plane 37. 1st to 1st in the sixth spatial filter in the first state
The mutual positional relationship of the third birefringent plates 33 to 35 in the optical axis directions q1 to q3 is equal to that of the first spatial filter 24 in the first state.

The birefringent plate driving section 25 includes a first birefringent plate 33
Is displaced by 180 degrees around an axis parallel to the optical axis 22,
Further, the third birefringent plate 35 is displaced by 90 degrees counterclockwise about the axis. The second birefringent plate 34 is always fixed. For this purpose, for example, two sets of mechanisms having the configuration shown in FIG. 4 are provided, and the first and third birefringent plates 33 and 35 are fitted into the holding members 61 of each mechanism, respectively. Is fixed to another holding member.
In this case, the optical path of the light after passing through the sixth spatial filter in the second state is parallel to the diagonal line of the pixel 42 of the imaging surface 41 from the optical path of the light after passing through the sixth spatial filter in the first state. The inclination direction of the inclined birefringent plate of the first and third birefringent plates 33 and 35 so as to be shifted in the direction U by a length of √ half of the pitch P of the arrangement of the pixels 42. And the inclination angles of the first and third birefringent plates 33 and 35 are adjusted.

FIGS. 18A to 18C show the first to third birefringent plates 33 to 35 of the sixth spatial filter in the second state.
FIG. 3 is a diagram showing projection directions of optical axis directions q1 to q3 of FIG. Optical axis direction q1 to q3 of first to third birefringent plates 33 to 35
Are cut out at approximately 45 degrees with respect to the optical axis 22. The projection direction of the first birefringent plate 33 in the optical axis direction q1 is 90 degrees clockwise from the horizontal direction x. The projection direction of the optical axis direction q2 of the second birefringent plate 34 is as shown in FIG.
The direction is the same as the direction shown in (B), and is 0 degrees clockwise from the horizontal direction x. The projection direction in the optical axis direction q3 of the third birefringent plate 35 is 135 degrees counterclockwise from the horizontal direction x.

FIGS. 19A to 19C show the first to third birefringent plates 33 in the sixth spatial filter in the second state.
It is a figure for demonstrating the separation light image of -35. The spatial frequency characteristics of the sixth spatial filter in the second state will be described with reference to FIG.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. As shown in FIG. 19A, the state of separation of the light while passing through the first birefringent plate 33 is the same as the state of separation of light described with reference to FIG.

The ordinary ray Lo and the extraordinary ray Le of the first birefringent plate 33 enter the second birefringent plate 34. FIG.
As shown in (B), the ordinary ray Lo of the first birefringent plate 33
Is defined as an extraordinary ray Loe of the second birefringent plate while passing through the second birefringent plate 34 from the original position by a separation width d2.
The first birefringent plate 34 is emitted in a 180-degree clockwise direction from the projection direction of the second birefringent plate 34 in the optical axis direction q2, that is, the horizontal direction x. Also, the first birefringent plate 33
As shown in FIG. 19B, the extraordinary ray Le is emitted as it is as the ordinary ray Leo of the second birefringent plate 24 without changing its position even while passing through the second birefringent plate 34. The ordinary ray of the second birefringent plate 34 corresponding to the ordinary ray Lo of the first birefringent plate 33 and the extraordinary ray of the second birefringent plate 24 corresponding to the extraordinary ray Le of the first birefringent plate 34 are: It does not exist for the reason described in the first embodiment.

The ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35. FIG.
As shown in (C), the ordinary ray Leo of the second birefringent plate 34
While passing through the third birefringent plate 35, the extraordinary ray Loe is separated into the ordinary rays Leoo, Loeo of the third birefringent plate 35 and the extraordinary rays Leoe, Loee of the third birefringent plate, and is emitted. I do. Ordinary ray L of the third birefringent plate 35
eoo, Loeo and the extraordinary ray of the third birefringent plate, Leeo,
Loee is separated by a separation width d3. The direction from the ordinary rays Leoo, Loeo of the third birefringent plate 35 to the extraordinary rays Leoe, Loee of the third birefringent plate is as follows.
The projection direction of the third birefringent plate 35 in the second state in the optical axis direction q3, that is, 135 in the counterclockwise direction from the horizontal direction x.
Equal to the direction of the degree.

Therefore, the separated state of the light finally obtained in the sixth spatial filter in the second state is the separated state shown in FIG. 19C, that is, the separated state shown in FIG. From the above, it can be seen that the separated state from the light finally obtained in the sixth spatial filter in the first and second states is equal. Therefore, the spatial frequency characteristic of the sixth spatial filter in the first state is equal to the spatial frequency characteristic of the sixth spatial filter in the second state.

Hereinafter, an imaging apparatus according to a seventh embodiment of the present invention will be described. The imaging apparatus according to the seventh embodiment includes a first
Compared with the imaging device 20 of the embodiment, the only difference is that the first spatial filter 24 is replaced with a seventh spatial filter, and the other components are the same. In the configuration of the imaging device according to the seventh embodiment, description of the same portions as those of the imaging device 20 according to the first embodiment will be omitted. Further, among the components constituting the imaging device of the seventh embodiment, the components having the same configuration as the imaging device 20 of the first embodiment are denoted by the same reference numerals.

The seventh spatial filter has first to third birefringent plates 33 to 35, and second and third birefringent plates 34, 35.
At least one of the 35 is inclined with respect to the reference plane 37. That is, the second birefringent plate 34 or the third birefringent plate 35 alone, or both the second and third birefringent plates 34 and 35 are inclined with respect to the reference plane 37. 1st to 1st in the seventh spatial filter in the first state
The mutual positional relationship of the third birefringent plates 33 to 35 in the optical axis directions q1 to q3 is equal to that of the first spatial filter 24 in the first state.

The birefringent plate driving section 25 includes a second birefringent plate 34.
Is displaced by 180 degrees around an axis parallel to the optical axis 22, and the third birefringent plate 35 is displaced by 90 degrees clockwise around the axis. The first birefringent plate 34 is always fixed. For this purpose, for example, two sets of mechanisms having the configuration shown in FIG. 4 are provided, and the second and third birefringent plates 34 and 35 are fitted into the holding members 61 of each mechanism, respectively. Is fixed to another holding member. In this case, the optical path of the light after passing through the seventh spatial filter in the second state is parallel to the diagonal line of the pixel 42 on the imaging surface 41 from the optical path of the light after passing through the seventh spatial filter in the first state. In the direction U, the pitch P of the arrangement of the pixels 42 is
The inclination direction and the inclination angle of the inclined birefringent plate of the second and third birefringent plates 34 and 35 are adjusted so as to be shifted by half the length.

FIGS. 20A to 20C show the first to third birefringent plates 33 to 35 of the seventh spatial filter in the second state.
FIG. 3 is a diagram showing projection directions of optical axis directions q1 to q3 of FIG. The optical axis directions q1 to q3 of the first to third birefringent plates 33 are respectively cut out at about 45 degrees with respect to the optical axis 22. First
The projection direction in the optical axis direction q1 of the birefringent plate 33 is as shown in FIG.
The direction is the same as the direction shown in (A), and is 90 degrees counterclockwise from the horizontal direction x. The optical axis direction q2 of the second birefringent plate 34
Is 180 degrees clockwise from the horizontal direction x.
Degrees. The projection direction in the optical axis direction q3 of the third birefringent plate 35 is 45 degrees clockwise from the horizontal direction x.

FIGS. 21A to 21C show first to third birefringent plates 33 in the seventh spatial filter in the second state.
It is a figure for demonstrating the separation light image of -35. The spatial frequency characteristic of the seventh spatial filter in the second state will be described with reference to FIG.

The light that has passed through the lens group 23 first enters the first birefringent plate 33. As shown in FIG. 21A, the state of separation of the light while passing through the first birefringent plate 33 is the same as the state of separation of the light described with reference to FIG.

The ordinary ray Lo and the extraordinary ray Le of the first birefringent plate 33 enter the second birefringent plate. FIG.
As shown in (B), the ordinary ray Lo of the first birefringent plate 33
Is defined as an extraordinary ray Loe of the second birefringent plate while passing through the second birefringent plate 34 from the original position by a separation width d2.
The second birefringent plate 34 in the second state is emitted in a direction shifted 180 degrees clockwise from the projection direction in the optical axis direction q2, that is, the horizontal direction x. In addition, the extraordinary ray Le of the first birefringent plate 33 does not change its position while passing through the second birefringent plate 34 as the ordinary ray Leo of the second birefringent plate 24 as shown in FIG. Is emitted as it is. The ordinary ray of the second birefringent plate 34 corresponding to the ordinary ray Lo of the first birefringent plate 33 and the extraordinary ray of the second birefringent plate 24 corresponding to the extraordinary ray Le of the first birefringent plate 34 are: It does not exist for the reason described in the first embodiment.

The ordinary ray Leo and the extraordinary ray Loe of the second birefringent plate 34 enter the third birefringent plate 35. FIG.
As shown in (C), the ordinary ray Leo of the second birefringent plate 34
While passing through the third birefringent plate 35, the extraordinary ray Loe is separated into the ordinary rays Leoo, Loeo of the third birefringent plate 35 and the extraordinary rays Leoe, Loee of the third birefringent plate, and is emitted. I do. Ordinary ray L of the third birefringent plate 35
eoo, Loeo and the extraordinary ray of the third birefringent plate, Leeo,
Loee is separated by a separation width d3. The direction from the ordinary rays Leoo, Loeo of the third birefringent plate 35 to the extraordinary rays Leoe, Loee of the third birefringent plate is as follows.
The projection direction of the third birefringent plate 35 in the second state in the optical axis direction q3, that is, the direction of 45 degrees counterclockwise from the horizontal direction x is equal to each other. Therefore, the separated state of the ordinary ray and the extraordinary ray finally obtained in the seventh spatial filter in the second state is the separated state shown in FIG. 21C, that is, the separated state shown in FIG.

From the above, it can be seen that the separated state of the ordinary ray and the extraordinary ray finally obtained in the seventh spatial filter in the first and second states is equal. Therefore, the spatial frequency characteristic of the seventh spatial filter in the first state is equal to the spatial frequency characteristic of the seventh spatial filter in the second state.

As described above, in the fourth to seventh spatial filters of the imaging devices of the fourth to seventh embodiments, the spatial frequency characteristics in the first state and the spatial frequency characteristics in the second state are equal. Therefore, in any of the imaging devices of the fourth to seventh embodiments, as described in the first embodiment, at least one of the fourth to seventh spatial filters in the fourth to seventh spatial filters is used for image shift.
Irrespective of the angular displacement of the birefringent plates, the image sensor 26 sets the subject 21 to the fourth to fourth of the appropriate spatial frequency characteristics.
An image can always be taken through the seventh spatial filter.

In the spatial filter, the direction of the optical axis of the first to third birefringent plates is set as shown in FIGS. 7, 10, 14, 16, 18, and 20.
As long as the positional relationship indicated by is maintained, all the final light separation states are the same. Therefore, two positional relationships are selected from the plurality of positional relationships described above, and the positional relationships in the optical axis direction of the first to third birefringent plates 33 to 35 that the spatial filters in the first and second states should maintain. Two selected positional relationships may be used. For example, the spatial filter in the first state may have the positional relationship shown in FIG. 10, and the spatial filter in the second state may have the positional relationship shown in FIG. In addition, when the optical axis directions of the first to third birefringent plates maintain the above-described plurality of positional relationships, the final order is obtained even if the order of the first to third birefringent plates 33 to 35 is changed in any state. The first to third birefringent plates 33 to 35,
May be changed from the order shown in the above figures.

The imaging devices of the first to seventh embodiments are examples of the imaging device of the present invention, and can be implemented in other various forms as long as the main operations are the same. In particular, the detailed operation of each device is not limited to this and may be realized by another operation as long as the same output is obtained. Further, the spatial filter of the imaging device of the present invention has one or a plurality of birefringent plates, and at least one of all birefringent plates is angularly displaced about the reference axis and is angularly displaced. If at least one of the birefringent plates is inclined with respect to a reference plane perpendicular to the reference axis, the present invention is not limited to the above-described first to seventh spatial filters, and may have another configuration. When two or more birefringent plates are inclined with respect to the reference plane, the angle formed between each birefringent plate and the reference plane may be changed for each birefringent plate. It is preferable to make the angle between each of the birefringent plates and the reference plane equal.
This is because it is easy to attach all the birefringent plates to the imaging device. Further, since the angle formed between each birefringent plate and the reference plane can be minimized as compared with the case where the angles are not equal, deterioration of an image due to the inclination of the birefringent plate and the like can be prevented. Because it can be suppressed.

In the imaging apparatus of the present invention, the angle at which the birefringent plate is angularly displaced, that is, the reference angle is preferably 180 degrees. This is for the following two reasons.

The first reason is as follows. CCD
A birefringent plate used in an image pickup device equipped with an image sensor generally uses quartz. Since a birefringent plate using quartz tends to be expensive, the shape of the birefringent plate currently on the market is, as shown in FIG.
It is a substantially rectangular arc. When the birefringent plate is angularly displaced by 90 degrees in the imaging apparatus of the present invention, it is considered that the shape of the birefringent plate needs to be circular or substantially cross-shaped as shown in FIG. When the birefringent plate is displaced by 180 degrees in the imaging apparatus of the present invention, the shape of the birefringent plate can be symmetrical with respect to the optical axis 22. 22
It is considered that a substantially rectangular shape shown in FIG. Therefore, when the reference angle is 180 degrees, the commercially available birefringent plate can be used as the birefringent plate of the imaging device of the present invention. The area of the birefringent plate of FIG. 22 is smaller than that of the circular birefringent plate and the birefringent plate of FIG. 23 if the radius r is equal to that of the circular birefringent plate and the birefringent plate of FIG. be able to. From these facts, it is preferable that the reference angle is 180 degrees because it is possible to suppress an increase in the manufacturing cost of the imaging device of the present invention.

The second reason is as follows. FIG.
(A) and FIG. 25 (A) show that the angle at which the birefringent plate is angularly displaced, that is, the reference angle is 180 degrees and 90 degrees, and the angle of inclination of the birefringent plate that is angularly displaced is 0 degree. In some cases, the positions of the optical paths 100 and 101 of the light from the subject after passing through the spatial filter before the birefringent plate is angularly displaced,
Shown respectively. In this case, the optical path of light from the subject after passing through the spatial filter after the birefringent plate has been angularly displaced is equal to the optical paths 100 and 101. The virtual rectangle 102 indicated by the two-dot chain line is a square whose one side length is half (P / 2) of the pitch P of the array of the pixels 42 on the imaging surface 41. 24A and 24B, the center of the virtual rectangle 102 coincides with the optical path 100. In FIGS. 25A and 25B,
The upper right vertex of the virtual rectangle 102 matches the optical path 101.

At least one of the birefringent plates that are angularly displaced in the spatial filter has a function of:
The distance between the optical path of light from the subject after passing through the spatial filter before the birefringent plate is angularly displaced and the optical path of light from the subject after passing through the spatial filter after the birefringent plate is angularly displaced is pitch Assume that it has been tilted to be √ of P. When the reference angle is 180 degrees, the light path 103 of the light from the subject after passing through the spatial filter before the birefringent plate is angularly displaced, and the subject after passing through the spatial filter after the birefringent plate is angularly displaced. The light path 104 of FIG.
As shown in the figure, the virtual rectangle 102 is located at two non-adjacent vertices. In this case, the optical paths 100 and 10
The distances from the pitches 3 and 104 are each 2/4 of the pitch P.
(P√2 / 4). When the reference angle is 90 degrees, the optical path 105 of the light from the subject after passing through the spatial filter before the birefringent plate is angularly displaced, and the subject after passing through the spatial filter after the birefringent plate is angularly displaced. Light path 10
6 is located at two non-adjacent vertices of the virtual rectangle 102 as shown in FIG. In this case, the distance between the optical path 101 and the optical paths 105 and 106 is half the pitch P.

As a result, the distance between the optical path 101 and the optical paths 103 and 104 when the reference angle is 180 degrees is equal to the distance between the optical path 101 and the optical path 10 when the reference angle is 90 degrees.
It is shorter than the distance to 5,106. In other words, the deviation of the optical path due to the inclination of the birefringent plate is smaller when the reference angle is 180 degrees than when the reference angle is 90 degrees. Therefore, it is considered that the inclination angle of the birefringent plate when the reference angle is 180 degrees is smaller than the inclination angle of the birefringent plate when the reference angle is 90 degrees. From the above, if the deviation of the optical path after passing through the spatial filter before and after the angular displacement of the birefringent plate is predetermined, the inclination angle of the birefringent plate can be minimized when the reference angle is 180 degrees. It is expected to be possible. Accordingly, when the reference angle is 180 degrees, in the output image represented by the output image signal generated by the imaging device of the present invention, the deterioration in image quality due to the inclination of the birefringent plate can be minimized. is there.

[0113]

As described above, according to the present invention, in the imaging apparatus, the positional relationship between the birefringent plate and the optical axis of the optical system in at least one of the spatial filters is changed by the image shift means. Thus, the at least one birefringent plate doubles as a refracting plate for image shift. Thereby, the imaging device of the present invention can be made smaller and lighter than the imaging device of the related art, and the assembly cost can be lower than that of the imaging device of the related art.

Further, according to the present invention, the spatial filter always maintains a predetermined spatial frequency characteristic regardless of a change in a positional relationship between the at least one birefringent plate and the optical axis. Therefore, the imaging device of the imaging device can always capture an image of a subject through a spatial filter having an appropriate spatial frequency characteristic.

Further, according to the present invention, the at least one birefringent plate is tilted in advance with respect to a reference plane perpendicular to the optical axis, and the image shift means is configured to control the at least one birefringent plate. The plate is angularly displaced about an axis parallel to the optical axis. Thereby, the accuracy of the image shift in the imaging device can be improved.

Further, according to the present invention, the angle and the direction between the inclined at least one birefringent plate and the reference plane are determined by the angular displacement of the birefringent plate and the light after passing through the spatial filter. Are shifted in a direction parallel to a diagonal line of the light receiving region by √ of the arrangement pitch of the light receiving region of the image sensor. Thereby, the convenience of the imaging device is improved.

Further, according to the present invention, the image shift means shifts one or a plurality of birefringent plates of all the birefringent plates to be angularly shifted by 180 degrees. Thereby, it is possible to minimize a decrease in image quality of an image due to the inclination of the birefringent plate. Thus, an increase in the manufacturing cost of the imaging device can be suppressed.

Further, according to the present invention, when a plurality of birefringent plates among all the birefringent plates to be angularly displaced are inclined with respect to the reference plane, each of the plurality of birefringent plates is The angles formed by the reference planes are equal to each other. This facilitates angle adjustment of the plurality of birefringent plates to be inclined when assembling the imaging device. Further, it is possible to reduce a decrease in image quality of the image caused by the aberration.

Further, according to the present invention, the spatial filter can always maintain a predetermined spatial frequency characteristic irrespective of whether or not the inclined birefringent plate or the birefringent plates are angularly displaced. Therefore, the imaging device can always capture an image of a subject through a spatial filter having an appropriate spatial frequency characteristic.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an imaging device 20 according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an imaging surface 41 of an imaging element 26 of the imaging device 20.

FIG. 3 is a diagram showing first and second states of a first spatial filter 24 of the imaging device 20.

FIG. 4 is a diagram showing a specific configuration of a birefringent plate driving unit 25 of the imaging device 20.

FIG. 5 is a diagram showing a position of a subject image formed on an imaging surface 41;

FIG. 6 is a diagram illustrating an output image represented by an output image signal generated by the imaging device.

FIG. 7 is a diagram illustrating a positional relationship of first to third birefringent plates 33 to 35 in the first spatial filter 24 in the first state in the direction of an image projected onto the xy plane in the optical axis directions q1 to q3. .

FIG. 8 is a diagram illustrating a light separation state of the first spatial filter 24 in the first state.

FIG. 9 is a diagram illustrating a final light separation state of the first spatial filter 24 in the first state.

FIG. 10 shows first to third filters in the first spatial filter 24 in the second state.
Xy in the optical axis directions q1 to q3 of the third birefringent plates 33 to 35
It is a figure which shows the positional relationship of the direction of the projection image on a plane.

FIG. 11 is a diagram illustrating a light separation state of a first spatial filter 24 in a second state.

FIG. 12 is a diagram illustrating first and second states of a second spatial filter 81 in an imaging device according to a second embodiment of the present invention.

FIG. 13 is a diagram illustrating first and second states of a third spatial filter 83 in an imaging device according to a third embodiment of the present invention.

FIG. 14 shows first to third birefringent plates 33 in a fourth spatial filter in a second state in an imaging device according to a fourth embodiment of the present invention.
FIG. 35 is a diagram illustrating a positional relationship between the optical axis directions q1 to q3 of the projection images onto the xy plane.

FIG. 15 is a diagram illustrating a light separation state of a fourth spatial filter in a second state.

FIG. 16 shows first to third birefringent plates 33 in a fifth spatial filter in a second state in an imaging device according to a fifth embodiment of the present invention.
FIG. 35 is a diagram illustrating a positional relationship between the optical axis directions q1 to q3 of the projection images onto the xy plane.

FIG. 17 is a diagram illustrating a light separation state of a fifth spatial filter in a second state.

FIG. 18 shows first to third birefringent plates 33 in a sixth spatial filter in a second state in an imaging device according to a sixth embodiment of the present invention.
FIG. 35 is a diagram illustrating a positional relationship between the optical axis directions q1 to q3 of the projection images onto the xy plane.

FIG. 19 is a diagram illustrating a light separation state of a sixth spatial filter in a second state.

FIG. 20 illustrates a first to third birefringent plates 33 in a seventh spatial filter in a second state in an imaging device according to a seventh embodiment of the present invention.
FIG. 35 is a diagram illustrating a positional relationship between the optical axis directions q1 to q3 of the projection images onto the xy plane.

FIG. 21 is a diagram illustrating a light separation state of a seventh spatial filter in a second state.

FIG. 22 is a diagram showing a currently available birefringent plate that can be used when the reference angle at which the birefringent plate is angularly displaced is 180 degrees in the imaging apparatus according to the first to seventh embodiments of the present invention. FIG.

FIG. 23 is a diagram illustrating a shape of a birefringent plate used when the reference angle at which the birefringent plate is angularly displaced is 90 degrees in the imaging devices according to the first to seventh embodiments of the present invention.

FIG. 24 is a diagram for explaining a shift caused by an inclination angle of a birefringent plate in an optical path of light after passing through a spatial filter in the imaging devices according to the first to seventh embodiments of the present invention.

FIG. 25 is a diagram for explaining a shift due to an inclination angle of a birefringent plate in an optical path of light after passing through a spatial filter in the imaging devices according to the first to seventh embodiments of the present invention.

FIG. 26 is a diagram for explaining the structure of a conventional imaging device.

DESCRIPTION OF SYMBOLS 20 Imaging device 22 Optical axis 23 Lens 24 First spatial filter 25 Birefringent plate driver 26 Image sensor 33 First birefringent plate 34 Second birefringent plate 35 Third birefringent plate 37 Reference plane 81 First 2 spatial filter 83 3rd spatial filter

Claims (7)

[Claims] 1. An optical system for condensing light from a subject, an imaging device having an imaging surface on which the light condensed by the optical system is formed, and between the optical system and the imaging device A spatial filter including at least one birefringent plate interposed between the spatial filter and at least one of all birefringent plates in the spatial filter to shift an optical path of light incident on the image sensor. Image shift means for changing a positional relationship between a birefringent plate and an optical axis of the optical system; and imaging for causing the image sensor to generate an image signal representing an image each time the image shift means changes the positional relationship. An imaging apparatus comprising: a control unit; and a combining unit that combines a plurality of the image signals. 2. A spatial frequency characteristic of the spatial filter before the positional relationship is changed is equal to a spatial frequency characteristic of the spatial filter after the positional relationship is changed. The imaging device according to 1. 3. The at least one birefringent plate of the at least one birefringent plate is inclined with respect to a reference plane perpendicular to the optical axis. The imaging apparatus according to claim 1, wherein the two birefringent plates are angularly displaced about a reference axis parallel to the optical axis. 4. A plurality of rectangular light receiving regions are arranged in a matrix on an image forming surface of the image pickup device. From the optical path of the light that has passed through the spatial filter before being displaced, the optical path of the light that has passed through the spatial filter after the birefringent plate to be angularly displaced has been angularly displaced is parallel to the diagonal line of the light receiving area. The angle formed by the inclined birefringent plate and the reference plane is such that the distance between the two optical paths is two in parallel with the diagonal line. The imaging apparatus according to claim 3, wherein the distance is set to be half of the distance between the two. 5. The imaging apparatus according to claim 3, wherein the angle at which the image shift means angularly displaces the birefringent plate to be angularly displaced is 180 degrees. 6. When a plurality of birefringent plates of all the birefringent plates to be angularly displaced are inclined with respect to the reference plane, each of the plurality of birefringent plates and the reference plane are displaced. The imaging device according to claim 3, wherein the angles are equal to each other. 7. A spatial frequency characteristic of the spatial filter before the birefringent plate to be angularly displaced is angularly displaced, and a spatial frequency characteristic of the spatial filter after the birefringent plate to be angularly displaced is angularly displaced. 4. The imaging device according to claim 3, wherein the spatial frequency characteristics are equal.