JP4481178B2 - Imaging method and imaging apparatus - Google Patents

Description

  The present invention relates to an imaging method and an imaging apparatus capable of realizing a small camera module having high resolving power.

  In solid-state imaging devices such as CCDs and CMOSs used for camera applications, attempts have been made to increase the number of pixels in order to increase the resolution of images. If the number of pixels is simply increased while keeping the size of each pixel as it is, the area of the solid-state imaging device is increased. Therefore, the number of elements obtained from one wafer is reduced and the yield is lowered, resulting in an increase in cost. For this reason, the number of pixels is increased by reducing the pixel size and the pixel pitch. However, since sensitivity and saturation output are generally proportional to the pixel size, there is a limit to improving the resolution only by reducing the pixel size.

  As a method for increasing the resolution without increasing the number of pixels, a method called “pixel shifting” has been proposed. In this method, a subject image is formed on the solid-state imaging device while being shifted in time by a half of the pixel pitch, and the subject image is sampled at a higher spatial frequency than determined by the pixel pitch. If the subject image is shifted in one direction, an image equivalent to that captured with twice the number of pixels can be obtained. In addition, if it is moved in two orthogonal directions, an image equivalent to an image captured with four times the number of pixels can be obtained.

  As a specific method for shifting the subject image formed on the solid-state image sensor relative to the solid-state image sensor, a method of swinging the solid-state image sensor itself two-dimensionally using an actuator, or configuring an optical system A method for mechanically moving a specific optical component is proposed. In addition to these, as a particularly promising method, a polarizer, a liquid crystal panel, and a quartz plate are arranged in the middle of the optical system described in Patent Document 1 or Patent Document 2, and the liquid crystal panel is electrically driven. A method of shifting the subject image by a predetermined distance is known. FIG. 11 is an explanatory view showing the principle.

  In FIG. 11, the quartz plate 113 is polished obliquely with respect to the specific optical axis A113, and transmits incident light by shifting the path according to the polarization direction. In FIG. 11, of the light incident on the quartz plate 113, a light beam having a polarization direction perpendicular to the paper surface proceeds straight as an ordinary light beam, and a light beam having a polarization direction parallel to the paper surface travels obliquely as an extraordinary light beam. An extraordinary ray is defined as a ray that does not follow Snell's law. Thereby, the path of incident light can be shifted according to the polarization direction. The amount D to be shifted can be determined by the thickness of the crystal plate 113, and is set to 1/2 of the pixel pitch of a solid-state image sensor (not shown) or an odd multiple thereof.

  Consider a case in which only the polarized light perpendicular to the paper surface is transmitted using the polarizer 111 among the light rays L from the subject side. The light that has passed through the polarizer 111 reaches the liquid crystal panel 112. The liquid crystal panel 112 is a twisted nematic type liquid crystal panel. When the driving voltage applied to the liquid crystal panel 112 is off, the polarization direction is rotated 90 degrees by the enclosed liquid crystal, and when the driving voltage is on, the polarization direction Will not change. Therefore, the light incident on the crystal plate 113 is shifted as a broken line as an extraordinary ray when the driving voltage is off, and travels straight as shown by the solid line when the driving voltage is on.

  If such an optical system is used and the thickness of the crystal plate 113 is adjusted, a subject image formed on a solid-state imaging device (not shown) by light transmitted through the crystal plate 113 is converted into a driving voltage for the liquid crystal panel 112. Can be shifted by 1/2 of the pixel pitch (or an odd multiple of 1/2 of the pixel pitch) in accordance with ON / OFF. If the drive voltage is turned on / off at high speed, an electrical signal is read from the solid-state image sensor in synchronism with this, and the image information obtained from each of the on state and the off state is synthesized, the number of pixels is doubled and the same The resolution of the image can be improved in the same manner as when picked up by a solid-state image pickup device having a size. If the resolution is improved by such a method, it is easy to obtain a high-definition image even if a part of the obtained image is cut out and enlarged (zoomed).

  In pixel shifting by such a method, the subject image can be shifted very stably and at high speed only by electrical on / off control without using a mechanical drive unit such as an actuator or a complicated mechanism system. Can do. Patent Document 2 discloses a method of performing pixel shifting two-dimensionally using this principle.

Patent Document 3 also discloses a similar method. Although the components of the optical system are not clearly described in Patent Document 3, a polarizer is indispensable because linearly polarized light is incident.
JP-A-2-52580 JP-A-4-63074 JP-A-61-247168

  However, since the methods disclosed in Patent Documents 1 to 3 all use linearly polarized light, light other than the linearly polarized light out of the light from the subject is lost. As a result, since the subject image formed on the solid-state image sensor becomes dark, the SN ratio is deteriorated and the image becomes conspicuous. In particular, when the subject is photographed in a low illuminance situation, the image quality is significantly deteriorated.

  The present invention solves the above problems, guides light from a subject to a solid-state imaging device with almost no loss, and realizes stable and high-speed pixel shifting (shifting of a subject image), thereby achieving high resolution of noise. An object is to provide an imaging method and an imaging apparatus capable of obtaining a small number of images.

  In the imaging method of the present invention, the relative positional relationship between an object image formed on a solid-state image sensor and the pixels of the solid-state image sensor is temporally changed by an odd multiple of half the arrangement pitch of the pixels. An imaging method for obtaining a resolution image, wherein light from a subject is separated into a plurality of lights having different polarization directions, and then combined to form one subject image on the solid-state imaging device. Switching between a band and a second time zone in which light from a subject is separated into a plurality of lights having different polarization directions and a plurality of subject images that overlap each other are formed on the solid-state image sensor. , Acquiring first image information about the one subject image based on signal information relating to light incident on each pixel of the solid-state imaging device in the first time zone, and acquiring the first image information of the solid-state imaging device in the second time zone. For each pixel Calculation using signal information regarding the emitted light, obtaining second image information about one of the plurality of subject images, using the first image information and the second image information, A high-resolution image of the subject is obtained. In the present invention, the “high-resolution image of a subject” refers to an image of a subject having a larger number of pixels than the number of pixels of a solid-state image sensor.

  The imaging apparatus of the present invention is disposed between the first transparent element and the second transparent element that shift the path of the light according to the polarization direction by the birefringence effect, and between the first transparent element and the second transparent element. A first optical system including a first liquid crystal panel that rotates transmitted light according to on / off of the applied voltage, a solid-state imaging device, and a first voltage that controls a voltage applied to the first liquid crystal panel. And a control means, wherein the light from the subject passes through the first optical system and is imaged as a subject image on the solid-state imaging device, and the voltage applied to the first liquid crystal panel By switching on / off, one subject image and a first subject image and a second subject image that overlap each other are alternately formed on the solid-state imaging device.

  According to the present invention, since the polarizer that is essential in the conventional pixel shifting method is not used, the pixel shifting (subject image shifting) can be performed stably and at high speed with almost no loss of light from the subject. it can. Therefore, an image with low noise and high resolution can be obtained. Thereby, a high-performance camera module can be realized.

  In addition, the image pickup apparatus of the present invention can perform high-speed, high-precision, one subject image and two subject images that overlap each other only by controlling on / off of a voltage applied to the liquid crystal panel. It is possible to form an image with stable switching.

  In the imaging method of the present invention, the second image information can be obtained using signal information from a pixel on which only one of the plurality of subject images is formed.

  Alternatively, an area composed of a plurality of adjacent pixels from which equivalent signal information is obtained in the first time zone is extracted, and the signal information in the second time zone immediately after the first time zone The second image information may be obtained by calculating the signal information in the second time period assuming that the signal information of the plurality of pixels in the area is the same value.

  In any case, the second image information about one subject image among a plurality of subject images overlapping each other can be easily calculated from the intensity distribution information of the light incident on the solid-state imaging device in the second time zone. be able to.

  In the imaging apparatus of the present invention, the first transparent element separates light from the subject into two polarized lights having different polarization directions, and separates the paths of the two polarized lights by a distance D. The first liquid crystal panel rotates the polarization directions of the two polarized lights emitted from the first transparent element by 0 degrees or 90 degrees according to an applied voltage, and the second transparent element One path of the two polarized lights emitted from one liquid crystal panel is shifted according to the polarization direction so that the paths of the two polarized lights coincide with each other, or the path interval between the two polarized lights is changed. It is preferable that the distance is increased to 2D, and the solid-state imaging device reads a light intensity distribution formed by the two polarized lights emitted from the second transparent element. As a result, one subject image and two subject images that overlap each other can be formed at desired positions on the solid-state imaging device.

  In this case, by using the light intensity distribution formed by the two polarized lights whose path intervals are expanded to the distance 2D, a light intensity distribution by only one of the two polarized lights is obtained, and this light is obtained. It is preferable to further include a signal processing circuit obtained by calculating the light intensity distribution of the image of the subject using the intensity distribution and the light intensity distribution formed by the two polarized lights whose paths are matched. Thereby, pixel shifting can be easily realized with almost no loss of light from the subject.

  The imaging apparatus according to the present invention further includes a third transparent element and a fourth transparent element that shift a path of light according to a polarization direction by a birefringence effect, and between the third transparent element and the fourth transparent element. And a second optical system comprising a second liquid crystal panel that rotates transmitted light according to on / off of an applied voltage, and second voltage control means for controlling a voltage applied to the second liquid crystal panel. The light from the subject passes through the first optical system and the second optical system and is imaged as a subject image on the solid-state imaging device, and is applied to the first liquid crystal panel and the second liquid crystal panel, respectively. On / off switching of the applied voltage, on the solid-state imaging device, the one subject image, the first subject image and the second subject image at different positions in the first direction, and the first direction Different from the first A third object image and the fourth object image different positions in the direction, it is preferable to sequentially imaged. As a result, high-resolution image information can be obtained two-dimensionally.

  Preferably, the first transparent element and the second transparent element are metal oxide films deposited obliquely. The third transparent element and the fourth transparent element are preferably metal oxide films deposited obliquely. Thereby, a low-cost and thin optical system can be realized.

  The first liquid crystal panel is preferably a twisted nematic liquid crystal panel. The second liquid crystal panel is preferably a twisted nematic liquid crystal panel. Thereby, it is possible to switch between transmission / transmission by rotating through 90 degrees without changing the polarization direction of incident polarized light at high speed and stably.

  The solid-state imaging device is preferably a MOS sensor. Thereby, the calculation process for every pixel can be performed at high speed.

  Hereinafter, the present invention will be described in detail by showing preferred embodiments.

(Embodiment 1)
FIG. 1 shows a main part of an imaging apparatus according to Embodiment 1 of the present invention. The imaging apparatus according to the present embodiment includes an optical system 10 having a first crystal plate 11, a second crystal plate 12, and a liquid crystal panel 13 disposed therebetween. The first crystal plate 11 and the second crystal plate 12 have optical axes A11 and A12 that are plane-symmetric with respect to the liquid crystal panel 13, as shown in the drawing. The liquid crystal panel 13 is disposed between the crystal plates 11 and 12 and includes opposed electrodes (not shown). The voltage control unit 14 controls on / off of the voltage applied to the liquid crystal panel 13.

  The quartz plates 11 and 12 have the same thickness and are polished at the same angle of 44 degrees and 50 minutes with respect to the optical axes A11 and A12. Of the rays incident perpendicular to the incident surfaces of the quartz plates 11 and 12, rays whose polarization direction is perpendicular to the plane of the paper are transmitted as ordinary rays without changing the path, but the polarization direction is parallel to the plane of the paper. A certain light beam is obliquely bent as an extraordinary light beam on the incident surface and is transmitted obliquely through the quartz plates 11 and 12. Then, the light beam obliquely transmitted through the quartz plates 11 and 12 is bent in the direction opposite to that at the time of incidence on the emission surface, and is eventually emitted as a light beam parallel to the incident light. That is, the light rays incident on the quartz plates 11 and 12 are separated into a light beam that travels straight as it is and a light beam whose path is shifted parallel to the straight light beam depending on the polarization direction.

  In FIG. 1, an optical system such as a lens and a mechanism system attached thereto are not shown.

  Usually, the light beam L from the subject enters the imaging device in a non-polarized state. In FIG. 1, the light beam L incident on the first crystal plate 11 in the non-polarized state from the left side is separated into two light beams according to the polarization direction as described above, and each reaches the liquid crystal panel 13. The liquid crystal panel 13 is a twisted nematic liquid crystal panel. When the drive voltage from the voltage control unit 14 is on, the polarization direction of the light beam is not changed by the liquid crystal panel 13. Accordingly, the two light beams separated by the first crystal plate 11 enter the second crystal plate 12 and then each take a path indicated by a solid line. On the other hand, when the drive voltage from the voltage control unit 14 is off, the polarization direction of the light beam is rotated 90 degrees by the liquid crystal sealed in the liquid crystal panel 13. Accordingly, the two light beams separated by the first crystal plate 11 enter the second crystal plate 12 and then take paths indicated by broken lines.

  That is, when the drive voltage is on, the two light beams separated by the first crystal plate 11 are combined by the second crystal plate 12, and one subject image is formed on the solid-state image sensor 15. On the other hand, when the drive voltage is OFF, the two light beams separated by the first crystal plate 11 form two subject images that are partially overlapped on the solid-state imaging device 15. These two subject images when the drive voltage is off are formed at positions that are separated from the one subject image when the drive voltage is on by the same distance D in the vertical direction of the paper surface of FIG.

  Here, each deviation D between the image forming position of the light beam indicated by the solid line and the image forming position of the light beam indicated by the broken line on the solid-state image sensor 15 is set to ½ of the pixel pitch of the solid-state image sensor 15. The thickness of the quartz plates 11 and 12 is adjusted. At this time, the shift amount 2D between the imaging positions due to the two light beams indicated by the broken lines separated by the polarization direction coincides with the pixel pitch. Such a condition can be realized by setting the thicknesses of the first crystal plate 11 and the second crystal plate 12 to about 213 μm, for example, when a solid-state imaging device having a pixel pitch of 2.5 μm is used. In the present embodiment, the shift amount D between the image forming positions of each light beam indicated by the solid line and the broken line is ½ of the pixel pitch. However, the present invention is not limited to this, and is an odd multiple of ½ of the pixel pitch. That is, the pixel pitch may be 3/2 times, 5/2 times, 7/2 times, or the like.

  An imaging method using such an imaging apparatus will be described below. Using the image pickup apparatus shown in FIG. 1, the voltage drive unit 14 repeatedly turns on / off the drive voltage applied to the liquid crystal panel 13 at high speed, and the electric signal from the solid-state image pickup device 15 is synchronized with the on / off switching. Read every frame. The switching interval of the drive voltage to the liquid crystal panel 13 can be several tens of milliseconds, for example.

  When the drive voltage is on, the light beam passes through a path indicated by a solid line, so that one subject image is formed on the solid-state image sensor 15. In this case, the signal information regarding the light incident on each pixel of the solid-state image sensor 15 is taken in as it is, and the data is accumulated as the first image information.

  On the other hand, when the drive voltage is off, the light ray passes through a path indicated by a broken line, so that two identical subject images partially overlapping each other are formed on the solid-state imaging device 15. This state is a so-called “double copy”. The image information obtained from the solid-state imaging device 15 in this state includes image information of a subject image that is shifted by a half pixel pitch with respect to one subject image at the time when the drive voltage is turned on immediately before. That is, the image information obtained when the drive voltage is off includes image information between pixels of the first image information obtained when the drive voltage is on. Therefore, the image information (second image information) about one of the subject images is reproduced from the image information about the two copied subject images obtained when the drive voltage is turned off, and the above-mentioned first information when the drive voltage is turned on. By superimposing on one image information, it becomes possible to obtain high-resolution image information having twice the number of pixels of the solid-state imaging device 15.

  A method of reproducing the image information of one subject image from the image information of two subject images that have been duplicated when the drive voltage is off will be described with reference to FIGS. 2 (A) and 2 (B). 2A and 2B are diagrams of the solid-state imaging device 15 as viewed from the subject side.

  When the drive voltage to the liquid crystal panel 13 is on, only one subject image 22 is formed on the solid-state image sensor 15 as shown in FIG.

  When the drive voltage to the liquid crystal panel 13 is off, two subject images 23 and 24 that are duplicated are formed on the solid-state image sensor 15 as shown in FIG. Here, the subject images 23 and 24 are set to be smaller than the sensing area of the solid-state imaging device 15.

  2A and 2B, a large number of small circles 25 are pixels of the solid-state imaging device 15, and are arranged at an array pitch P along the X axis and the Y axis.

  As described in FIG. 1, in the frame in FIG. 2A, the image information of the subject image 22 is captured as it is as the first image information.

  In the frame in FIG. 2B, the subject image 23 and the subject image 24 are shifted to the opposite sides in the X-axis direction by half the pixel pitch P with respect to the subject image 22 in FIG. That is, the subject image 23 and the subject image 24 are shifted by the pixel pitch P in the X-axis direction. In general use, since the light intensity in each polarization direction is the same, the subject image 23 and the subject image 24 are also completely equal in light intensity.

  First, in FIG. 2B, among the pixels on the I line parallel to the X axis, the pixels (I, J) into which only the light constituting the subject image 24 is incident and the light constituting the subject image 23 is not incident. ). Here, the pixel (I, J) represents a pixel on the I row and the J column. As in the present embodiment, when the subject images 23 and 24 are shifted in the X-axis direction by a half-pixel pitch with respect to the subject image 22, they are to the right of the pixel (I, J) in the X-axis direction. Neither of the subject images 23 and 24 is formed in the adjacent pixel (I, J + 1), and no signal is generated. In the adjacent pixel (I, J−1) on the left side in the X-axis direction, the subject images 23 and 24 overlap.

In the state of FIG. 2B, assuming that only the subject image 24 is virtually formed on the solid-state imaging device 15, the signal intensity of the subject image 24 at the pixel (I, n) at a certain moment. Is defined as P (I, n). Further, when the subject images 23 and 24 are actually formed in a double copy on the solid-state image sensor 15, the signal intensity at the pixel (I, n) at the same moment is expressed as Q (I, n). It is defined as Here, n is a natural number. Then
Q (I, n-1) = P (I, n-1) + P (I, n) (1)
Is established. Further, as described above, since the pixel (I, J) is a signal of only the subject image 24,
Q (I, J) = P (I, J) (2)
It becomes.

  Since the signal intensity Q (I, n) when the subject images 23 and 24 are imaged on the solid-state image sensor 15 by double copying is signal information that can be detected, Equations (1) and (2) If used, P (I, J-1), P (I, J-2),... Based on P (I, J), that is, Q (I, J), for each pixel on the I row. .. Can be obtained in order, and it is possible to acquire all the signal information of the subject image 24 in each pixel on the I row. Signal information can be obtained in the same procedure for each pixel on each row other than the I row on which the subject image 24 is formed. As a result, image information (second image information) about one subject image 24 can be obtained from the image information about the two subject images 23 and 24 that have been duplicated.

  The subject images 23 and 24 have only about half the light intensity of the subject image 22. Therefore, the second image information about the reproduced subject image 24 is amplified by a factor of 2 and combined with the first image information about the subject image 22 captured in the frame in FIG. Thus, it is possible to obtain image information that is pseudo-doubled in the X-axis direction.

  In FIG. 2B, in order to find a pixel (I, J) on the I line on which only light constituting one of the subject images formed by double copying is incident. What is necessary is as follows. The optical signal intensity of each pixel is confirmed in order along the I row from the pixel currently receiving light on the I row. If there is a pixel whose optical signal intensity is 0 for the first time (pixel (I, J + 1) in FIG. 2B), the pixel immediately before this pixel is a pixel on which only light constituting one subject image is incident. This corresponds to (pixel (I, J) in FIG. 2B).

  The above calculation is performed by a signal processing circuit (not shown) connected to the solid-state imaging device 15.

  The use of a MOS type as the solid-state imaging device 15 is particularly desirable because signal extraction calculation for each pixel can be performed at high speed.

In the above description, an example in which the shift amount D of the subject images 23 and 24 in FIG. 2B with respect to the subject image 22 in FIG. 2A is half the pixel pitch P of the solid-state image sensor 15 has been shown. The invention is not limited to this, and the same effect can be obtained if the shift amount D is an odd multiple of half the pixel pitch P. When the shift amount D is L times half of the pixel pitch P (L is an odd number), the above equation (1) is
Q (I, n-L) = P (I, n-L) + P (I, n) (3)
Equation (2) becomes
Q (I, J) = P (I, J) (4)
Q (I, J-1) = P (I, J-1)
...
...
Q (I, JL) = P (I, JL)
It becomes.

  The larger the value of L, the greater the number of pixels on which only light constituting one of the two subject images is incident during double copying. However, it is necessary to increase the thickness of the quartz plates 11 and 12 in FIG. 1 to L times that of L = 1 in accordance with the value of L. Therefore, L should be selected in consideration of a thickness that can be easily processed as a quartz plate.

  If a white LED or the like is used as the illumination light source for the subject and the illumination light source is blinked in synchronization with the on / off of the voltage applied to the liquid crystal panel 13, the S / N ratio (signal intensity ratio to noise) is increased. It is possible and effective.

(Embodiment 2)
FIG. 3 shows a main part of the imaging apparatus according to Embodiment 2 of the present invention. The imaging apparatus of the present embodiment includes a first optical system 30A having a first crystal plate 31, a second crystal plate 32, and a first liquid crystal panel 33 disposed therebetween, and a third crystal plate. 35, a fourth crystal plate 36, and a second optical system 30B having a second liquid crystal panel 37 disposed therebetween.

  The first crystal plate 31 and the second crystal plate 32 have optical axes A31 and A32 that are plane-symmetric with respect to the first liquid crystal panel 33, as shown in the drawing. The first liquid crystal panel 33 is disposed between the first and second crystal plates 31 and 32 and includes opposed electrodes (not shown).

  The second optical system 30B including the third crystal plate 35, the fourth crystal plate 36, and the second liquid crystal panel 37 includes a first crystal plate 31, the second crystal plate 32, and the first liquid crystal panel 33 described above. One optical system 30A has the same configuration as that rotated by 90 ° with respect to the optical axis.

  The voltage controller 34 controls on / off of the voltage applied to the first and second liquid crystal panels 33 and 37.

  The quartz plates 31, 32, 35, and 36 have the same thickness and are polished at the same angle of 44 degrees and 50 minutes with respect to the optical axes A31, A32, A35, and A36.

  If the voltage control unit 34 performs the control as shown in Table 1 for each frame, in addition to the double copy (pixel shift) in the X-axis direction as shown in FIG. Double copying (pixel shifting) is possible.

  Voltage control for each frame is performed in the order of frame numbers 1 to 4 in Table 1, and a signal is captured from the solid-state imaging device 15 for each frame. In frame 2 and frame 4, the subject image is duplicated, but image information about a single subject image can be reproduced by the method described in the first embodiment. This is combined with the image information obtained in frames 1 and / or 3.

  Thus, in this embodiment, pixel shifting is performed two-dimensionally in the X-axis direction and the Y-axis direction. As a result, it is possible to obtain image information that is pseudo-doubled in each of the X-axis direction and the Y-axis direction. That is, two-dimensional high resolution can be achieved.

  In the above example, the first and second liquid crystal panels 33 and 37 are driven by the common voltage control unit 34, but the first and second liquid crystal panels 33 and 37 may be driven by separate voltage control units.

(Embodiment 3)
FIG. 4 shows a main part of the imaging apparatus according to Embodiment 3 of the present invention. In the present embodiment, instead of the first crystal plate 11 and the second crystal plate 12 of the first embodiment, a first oblique deposition film 41 and a second oblique deposition film 42 are used. The imaging apparatus according to the present embodiment includes a block-shaped optical system 40 in which a liquid crystal panel 43 having first and second obliquely deposited films 41 and 42 formed on both sides is sealed with a transparent cell 45. Performs the same operation as the imaging device.

  As shown in the figure, each of the first obliquely deposited film 41 and the second obliquely deposited film 42 has optical axes A41 and A42 that are plane-symmetric with respect to the liquid crystal panel 43, and has birefringence. It functions similarly to the crystal plate 11 and the second crystal plate 12. In FIG. 4, the first oblique deposition film 41 and the second oblique deposition film 42 are directly formed on the liquid crystal panel 43, but another sheet or substrate on which these are deposited may be attached to the liquid crystal panel 43.

  The obliquely deposited films 41 and 42 are literally obtained by forming a film on the substrate from an oblique direction by a vacuum deposition method. When a heavy metal oxide such as tantalum oxide, tungsten oxide, or titanium oxide as a film material is melted by an electron beam, and vapor deposition is performed at room temperature while introducing an oxygen gas into a film formation tank as necessary, the film material becomes as shown in FIG. It adheres to the substrate in the form of a transparent diagonal column. Since the film density is different between the direction of the optical axes A41 and A42 and the direction orthogonal to the direction (the in-paper direction of FIG. 4 and the direction perpendicular to the paper surface), the refractive index is different. That is, the obliquely deposited films 41 and 42 have birefringence with different refractive indexes in the triaxial direction, like the biaxial crystal.

  For example, when tantalum oxide is deposited on a substrate from a direction of about 70 ° with respect to the normal, the resulting film is composed of a number of columns inclined by 30 to 35 ° with respect to the substrate normal. The birefringence (Δn) of this film is about 0.08. This is an extremely large value compared to the birefringence of quartz of 0.01. This means that when an obliquely deposited film is used, the film thickness for obtaining equivalent retardation can be made extremely thin.

  For example, when the imaging position shift of half the pixel pitch described in the first embodiment is performed using the solid-state imaging device 15 having a pixel pitch of 2.5 μm, if a crystal plate is used, as described in the first embodiment. The thickness needs to be 200 μm or more, but if a tantalum oxide oblique vapor deposition film is used, the thickness is less than 30 μm. An obliquely deposited film having such a thickness can be easily formed and can be mass-produced.

  However, the obliquely deposited film has a problem that the magnitude of birefringence easily changes with changes in the surrounding environment. The influence mainly due to fluctuations in humidity is large. When the humidity is high, water molecules enter the gaps between the obliquely deposited films, and the birefringence becomes small. Conversely, birefringence increases as humidity decreases.

  As shown in FIG. 4, by sealing the obliquely deposited films 41 and 42 with the transparent cell 45, the magnitude of birefringence of the obliquely deposited films 41 and 42 can be stabilized. However, the sealing method is not limited to this, and a method of forming a protective layer on the surface of the film or attaching a protective sheet may be used.

  As described above, by using the obliquely deposited films 41 and 42 as elements that shift the path of the light according to the polarization direction due to the birefringence effect, the economical efficiency of the apparatus is improved as compared with the case where a quartz plate is used. it can.

(Embodiment 4)
FIG. 5 shows a main part of an imaging apparatus according to Embodiment 4 of the present invention. The imaging apparatus of the present embodiment includes an optical system 50 having a first crystal plate 51, a second crystal plate 52, and a liquid crystal panel 53 disposed therebetween. In the first embodiment (see FIG. 1), the first crystal plate 11 and the second crystal plate 12 have the optical axes A11 and A12 that are plane-symmetric with respect to the liquid crystal panel 13. In the embodiment, the optical axis A51 of the first crystal plate 51 and the optical axis A52 of the second crystal plate 52 are parallel to each other. The rest is the same as the imaging apparatus of the first embodiment.

  In the present embodiment, when the drive voltage applied to the liquid crystal panel 53 is off, the two light beams separated by the first crystal plate 51 pass through a path indicated by a broken line, and thus one solid image sensor 15 is provided on the solid-state imaging device 15. A subject image is formed. In this case, the signal information regarding the light incident on each pixel of the solid-state image sensor 15 is taken in as it is, and the data is accumulated as the first image information.

  On the other hand, when the drive voltage applied to the liquid crystal panel 53 is on, the two light beams separated by the first crystal plate 51 form two subject images that overlap each other on the solid-state imaging device 15. To do. These two subject images when the drive voltage is on are formed at positions that are the same distance D apart from each other subject image when the drive voltage is off in the vertical direction of the paper surface of FIG.

  In the same manner as described in the first embodiment, image information (second image information) about one of the subject images is obtained from the image information about the two copied subject images obtained when the drive voltage is turned on. It is reproduced and superimposed on the first image information when the drive voltage is off. Thus, high-resolution image information having twice the number of pixels of the solid-state image sensor 15 can be obtained.

(Embodiment 5)
FIG. 6 shows a main part of an imaging apparatus according to Embodiment 5 of the present invention. The imaging apparatus according to the present embodiment includes an optical system 60 having a first crystal plate 61, a second crystal plate 62, and a liquid crystal panel 63 disposed therebetween. The first crystal plate 61 and the second crystal plate 62 have optical axes A61 and A62 that are plane-symmetric with respect to the liquid crystal panel 63, as shown in the drawing. The liquid crystal panel 63 is disposed between the crystal plates 61 and 62 and includes opposed electrodes (not shown). The voltage control unit 64 controls on / off of the voltage applied to the liquid crystal panel 63.

  The quartz plates 61 and 62 have the same thickness and are polished at the same angle of 44 degrees and 50 minutes with respect to the optical axes A61 and A62. Of the light rays perpendicularly incident on the incident surfaces of the quartz plates 61 and 62, the light rays whose polarization direction is perpendicular to the paper surface are transmitted as ordinary rays without changing the path, but the polarization direction is parallel to the paper surface. A certain ray is bent as an extraordinary ray on the incident surface and is transmitted obliquely through the quartz plates 61 and 62. Then, the light beam obliquely transmitted through the quartz plates 61 and 62 is bent in the direction opposite to that at the time of incidence on the exit surface, and is eventually emitted as a light beam parallel to the incident light. That is, the light rays incident on the quartz plates 61 and 62 are separated into a light beam that travels straight as it is and a light beam whose path is shifted parallel to the straight light beam depending on the polarization direction.

  In FIG. 6, an optical system such as a lens and a mechanism system attached thereto are not shown.

  Usually, the light beam L from the subject enters the imaging device in a non-polarized state. In FIG. 6, the light beam L incident on the first crystal plate 61 in the non-polarized state from the left side is separated into two light beams according to the polarization direction as described above, and each reaches the liquid crystal panel 63. The liquid crystal panel 63 is a twisted nematic liquid crystal panel. When the drive voltage from the voltage controller 64 is on, the polarization direction of the light beam is not changed by the liquid crystal panel 63. Accordingly, the two light beams separated by the first crystal plate 61 enter the second crystal plate 62 and then take paths indicated by solid lines. On the other hand, when the drive voltage from the voltage controller 64 is off, the polarization direction of the light beam is rotated 90 degrees by the liquid crystal sealed in the liquid crystal panel 63. Accordingly, the two light beams separated by the first crystal plate 61 enter the second crystal plate 62 and then take paths indicated by broken lines.

  That is, when the drive voltage is on, the two light beams separated by the first crystal plate 61 are combined by the second crystal plate 62, and one subject image is formed on the solid-state image sensor 65. On the other hand, when the drive voltage is off, the two light beams separated by the first crystal plate 61 form two subject images that overlap each other on the solid-state image sensor 65. The two subject images when the drive voltage is off are formed at positions that are separated from the one subject image when the drive voltage is on by the same distance D in the vertical direction of the paper surface of FIG.

  Here, each deviation D between the image forming position of the light beam indicated by the solid line and the image forming position of the light beam indicated by the broken line on the solid-state image sensor 65 is ½ of the pixel pitch of the solid-state image sensor 65. The thickness of the quartz plates 61 and 62 is adjusted. At this time, the shift amount 2D between the imaging positions due to the two light beams indicated by the broken lines separated by the polarization direction coincides with the pixel pitch. Such a condition can be realized by setting the thicknesses of the first crystal plate 61 and the second crystal plate 62 to about 213 μm, for example, when a solid-state imaging device having a pixel pitch of 2.5 μm is used. In the present embodiment, the shift amount D between the image forming positions of each light beam indicated by the solid line and the broken line is ½ of the pixel pitch. However, the present invention is not limited to this, and is an odd multiple of ½ of the pixel pitch. That is, the pixel pitch may be 3/2 times, 5/2 times, 7/2 times, or the like.

  An imaging method using such an imaging apparatus will be described below. Using the image pickup apparatus shown in FIG. 6, the voltage drive unit 64 repeatedly turns on / off the drive voltage applied to the liquid crystal panel 63 at high speed. Read every frame. The switching interval of the drive voltage to the liquid crystal panel 63 can be several tens of milliseconds, for example.

  When the drive voltage is on, the light beam passes through a path indicated by a solid line, so that one subject image is formed on the solid-state image sensor 65. In this case, the signal information regarding the light incident on each pixel of the solid-state image sensor 65 is taken in as it is, and the data is accumulated as the first image information.

  On the other hand, when the drive voltage is off, the light ray passes through a path indicated by a broken line, so that two identical subject images partially overlapping each other are formed on the solid-state imaging device 65. This state is a so-called “double copy”. The image information obtained from the solid-state image sensor 65 in this state includes image information of a subject image that is shifted by a half pixel pitch with respect to one subject image at the time when the drive voltage is turned on immediately before. That is, the image information obtained when the drive voltage is off includes image information between pixels of the first image information obtained when the drive voltage is on. Therefore, the image information (second image information) about one of the subject images is reproduced from the image information about the two copied subject images obtained when the drive voltage is turned off, and the above-mentioned first information when the drive voltage is turned on. When superposed on one image information, it is possible to obtain high-resolution image information having twice the number of pixels of the solid-state image sensor 65.

  A method of reproducing the image information of one subject image from the image information of two subject images that are duplicated when the drive voltage is off will be described with reference to FIGS. 7A and 7B. 7A and 7B are views of the solid-state imaging device 65 as viewed from the subject side.

  When the drive voltage to the liquid crystal panel 63 is on, only one subject image 72 is formed on the solid-state image sensor 65 as shown in FIG.

  When the drive voltage to the liquid crystal panel 63 is off, two object images 73 and 74 that are duplicated are formed on the solid-state image sensor 65 as shown in FIG. 7B. Here, the subject images 73 and 74 may be larger or smaller than the sensing area of the solid-state image sensor 65.

  7A and 7B, a large number of small circles 25 are pixels of the solid-state imaging device 65, and are arranged at an array pitch P along the X axis and the Y axis.

  As described with reference to FIG. 6, in the frame in FIG. 7A, the image information of the subject image 72 is directly captured as the first image information.

  In the frame in FIG. 7B, the subject image 73 and the subject image 74 are offset from each other in the X-axis direction by half the pixel pitch P with respect to the subject image 72 in FIG. That is, the subject image 73 and the subject image 74 are shifted by the pixel pitch P in the X-axis direction. In general use, since the light intensity in each polarization direction is the same, the subject image 73 and the subject image 74 are also completely equal in light intensity.

  First, the first image information captured in the frame in FIG. 7A is analyzed. Equivalent light intensity signals are obtained in rows parallel to the X-axis direction as the shifting direction of the subject image, that is, in rows 1, 2,..., I-1, I, I + 1,. An area composed of a plurality of (two in this example) adjacent pixels is extracted. For example, in FIG. 7A, when the light intensity signals of the pixel (I, J) and the pixel (I, J + 1) on the I row are the same, an area 75 including these two pixels is extracted.

  Thereafter, the driving voltage of the liquid crystal panel 65 is turned off, and two object images 73 and 74 that are duplicated as shown in FIG. 7B are formed. Of the subject, light emitted from a portion corresponding to the area 75 in FIG. 7A enters the area 76 and the area 77 separately in FIG. 7B. Here, the area 76 corresponds to the subject image 73, and the area 77 corresponds to the subject image 74.

In the state of FIG. 7B, assuming that only the subject image 74 is virtually formed on the solid-state image sensor 65, the signal intensity of the subject image 74 at the pixel (M, N) at a certain moment. Is defined as P (M, N). Further, when the subject images 73 and 74 are actually formed in a double copy on the solid-state image sensor 65, the signal intensity at the pixel (M, N) at the same moment is Q (M, N). It is defined as Then
Q (M, N) = P (M, N) + P (M, N + 1) (5)
Is established.

  Since the same light intensity signal is obtained in the pixel (I, J) and the pixel (I, J + 1) adjacent to each other in the area 75 in FIG. 7A, the virtual pixel (I, J) sandwiched between them is obtained. J + 0.5) is very likely to have the same light intensity signal.

  Further, in the imaging apparatus of the present embodiment, the voltage applied to the liquid crystal panel 63 is switched on / off at high speed, so that the light intensity distribution of the subject image 72 in FIG. There is a very high probability that the light intensity distributions of the subject image 73 and the subject image 74 in FIG.

  Therefore, the light emitted from the portion corresponding to the virtual pixel (I, J + 0.5) in FIG. 7A in the subject is the light constituting the subject image 73 in FIG. 7B immediately after this. Is incident on the pixel (I, J), and is incident on the pixel (I, J + 1) as light constituting the subject image 74.

  Therefore, it is highly probable that the light intensity signals of the pixel (I, J) and the pixel (I, J + 1) in the area 75 of FIG. 7A are the same in the state of FIG. 7B.

Based on the above assumption, if both the pixel (I, J) and the pixel (I, J + 1) in the area 75 have obtained the optical signal intensity A in the state of FIG.
P (I, J + 1) = A / 2 (6)
Holds.

  Signal strengths Q (I, 1),..., Q (I, J),... When the subject images 73 and 74 are stored in a double copy on the solid-state image sensor 65 are detected. Since it is signal information that can be obtained, if Expression (5) and Expression (6) are used, P (I, J) is obtained for each pixel on the I row, and P (I) is repeatedly obtained by using Expression (5). (I, J-1), P (I, J-2),..., Or conversely, P (I, J + 2), P (I, J + 3),. It is possible to acquire all the signal information of the subject image 74 in each pixel above. Signal information can be obtained in the same procedure for each pixel on each row other than the I row on which the subject image 74 is formed. As a result, the image information (second image information) about one subject image 74 can be obtained from the image information about the two subject images 73 and 74 that are duplicated.

  The subject images 73 and 74 have only about half the light amount of the subject image 72. Therefore, the second image information about the reproduced subject image 74 is amplified by a factor of 2, and is combined with the first image information about the subject image 72 captured in the frame in FIG. Thus, it is possible to obtain image information that is pseudo-doubled in the X-axis direction.

  The above calculation is performed by a signal processing circuit (not shown) connected to the solid-state image sensor 65.

  The use of a MOS type as the solid-state imaging device 65 is particularly desirable because signal extraction calculation for each pixel can be performed at high speed.

In the above description, an example in which the shift amount D of the subject images 73 and 74 in FIG. 7B with respect to the subject image 72 in FIG. 7A is half the pixel pitch P of the solid-state image sensor 65 has been shown. The invention is not limited to this, and the same effect can be obtained if the shift amount D is an odd multiple of half the pixel pitch P. When the shift amount D is L times half of the pixel pitch P (L is an odd number), the above equation (5) is
Q (M, N−L) = P (M, N−L) + P (M, N) (7)
Thus, image information (second image information) about the subject image 74 can be obtained by calculating in the same procedure as described above.

  According to the value of L, it is necessary to increase the thickness of the quartz plates 61 and 62 in FIG. 6 to L times that in the case where L = 1. Therefore, L should be selected in consideration of a thickness that can be easily processed as a quartz plate.

  If a white LED or the like is used as the illumination light source for the subject and the illumination light source is blinked in synchronization with the on / off of the voltage applied to the liquid crystal panel 63, the S / N ratio (signal intensity ratio to noise) is increased. It is possible and effective.

  As described above, in general use, the intensity for each polarization direction of the light coming from the subject is the same, and this embodiment has been described based on this assumption. If the transmittances of the two lights separated by the first crystal plate 61 in the liquid crystal panel 63 are not the same due to the polarization direction and the on / off state of the drive voltage, the above formula (5) And Equation (6) are as shown in Equation (8) and Equation (9) below, respectively.

Q (M, N) = α1P (M, N) + β1P (M, N + 1) (8)
P (I, J + 1) = α2A / (α2 + β2) (9)
Here, when polarized light whose polarization direction is perpendicular to the paper surface of FIG. 6 is incident on the liquid crystal panel 63, the transmittance of the polarized light when the drive voltage to the liquid crystal panel 63 is turned off is α1, and the light is turned on. Then, the transmittance of the polarized light is α2. Similarly, when polarized light whose polarization direction is parallel to the paper surface of FIG. 6 is incident on the liquid crystal panel 63, the transmittance of the polarized light when the drive voltage to the liquid crystal panel 63 is turned off is turned on by β1. In this case, the transmittance of the polarized light is β2. If each transmittance in each case is measured in advance, in the same manner as described above, the image information (second image) about one subject image is obtained from the image information about two subject images that are duplicated. Image information).

  In the first embodiment, the transmittances of the two polarized lights separated by the first crystal plate 11 in the liquid crystal panel 13 in the first embodiment are not the same depending on the polarization direction and the on / off state of the driving voltage. The same applies in cases.

(Embodiment 6)
FIG. 8 shows the main part of an imaging apparatus according to Embodiment 6 of the present invention. The imaging device of the present embodiment includes a first optical system 80A having a first crystal plate 81, a second crystal plate 82, and a first liquid crystal panel 83 disposed therebetween, and a third crystal plate. 85, a fourth crystal plate 86, and a second optical system 80B having a second liquid crystal panel 87 disposed therebetween.

  The first crystal plate 81 and the second crystal plate 82 have optical axes A81 and A82 that are plane-symmetric with respect to the first liquid crystal panel 83, as shown in the drawing. The first liquid crystal panel 83 is disposed between the first and second crystal plates 81 and 82 and includes opposed electrodes (not shown).

  The second optical system 80B including the third crystal plate 85, the fourth crystal plate 86, and the second liquid crystal panel 87 is the first optical plate 80 including the first crystal plate 81, the second crystal plate 82, and the first liquid crystal panel 83. One optical system 80A has the same configuration as that rotated by 90 ° with respect to the optical axis.

  The voltage controller 84 controls on / off of the voltage applied to the first and second liquid crystal panels 83 and 87.

  The quartz plates 81, 82, 85, 86 have the same thickness and are polished at the same angle of 44 degrees 50 minutes with respect to the optical axes A81, A82, A85, A86.

  If the voltage control unit 84 performs control as shown in Table 2 for each frame, in addition to the double copy (pixel shift) in the X-axis direction as shown in FIG. Double copying (pixel shifting) is possible.

  Voltage control for each frame is performed in the order of frame numbers 1 to 4 in Table 2, and a signal is captured from the solid-state imaging device 65 for each frame. In frame 2 and frame 4, the subject image is duplicated, but image information about a single subject image can be reproduced by the method described in the fifth embodiment. This is combined with the image information obtained in frames 1 and / or 3.

  Thus, in this embodiment, pixel shifting is performed two-dimensionally in the X-axis direction and the Y-axis direction. As a result, it is possible to obtain image information that is pseudo-doubled in each of the X-axis direction and the Y-axis direction. That is, two-dimensional high resolution can be achieved.

  In the above example, the first and second liquid crystal panels 83 and 87 are driven by the common voltage control unit 84. However, the first and second liquid crystal panels 83 and 87 may be driven by separate voltage control units.

(Embodiment 7)
FIG. 9 shows a main part of an imaging apparatus according to Embodiment 7 of the present invention. In the present embodiment, a first oblique deposition film 91 and a second oblique deposition film 92 are used in place of the first quartz plate 61 and the second quartz plate 62 of the fifth embodiment. The imaging apparatus according to the present embodiment includes a block-shaped optical system 90 in which a liquid crystal panel 93 having first and second obliquely deposited films 91 and 92 formed on both sides is sealed with a transparent cell 95. Performs the same operation as the imaging device.

  As shown in the figure, each of the first oblique deposition film 91 and the second oblique deposition film 92 has optical axes A91 and A92 that are plane-symmetric with respect to the liquid crystal panel 93, has birefringence, and has the first structure shown in FIG. It functions similarly to the crystal plate 61 and the second crystal plate 62. In FIG. 9, the first oblique deposition film 91 and the second oblique deposition film 92 are directly formed on the liquid crystal panel 93, but another sheet or substrate on which these are deposited may be attached to the liquid crystal panel 93.

  The obliquely deposited films 91 and 92 are literally obtained by forming a film on the substrate from an oblique direction by a vacuum deposition method. When a heavy metal oxide such as tantalum oxide, tungsten oxide, or titanium oxide as a film material is melted by an electron beam and is deposited at room temperature while introducing an oxygen gas into a film formation tank as necessary, the film material becomes as shown in FIG. It adheres to the substrate in the form of a transparent diagonal column. Since the film density is different between the direction of the optical axes A91 and A92 and the direction orthogonal to the direction (the in-paper direction of FIG. 9 and the direction perpendicular to the paper surface), the refractive index is different. That is, the obliquely deposited films 91 and 92 have birefringence with different refractive indexes in the triaxial direction, like the biaxial crystal.

  For example, when tantalum oxide is deposited on a substrate from a direction of about 70 ° with respect to the normal, the resulting film is composed of a number of columns inclined by 30 to 35 ° with respect to the substrate normal. The birefringence (Δn) of this film is about 0.08. This is an extremely large value compared to the birefringence of quartz of 0.01. This means that when an obliquely deposited film is used, the film thickness for obtaining equivalent retardation can be made extremely thin.

  For example, when the imaging position shift of half the pixel pitch described in the fifth embodiment is performed using the solid-state imaging device 65 having a pixel pitch of 2.5 μm, a crystal plate is used as described in the fifth embodiment. The thickness needs to be 200 μm or more, but if a tantalum oxide oblique vapor deposition film is used, the thickness is less than 30 μm. An obliquely deposited film having such a thickness can be sufficiently formed and can be mass-produced.

  However, the obliquely deposited film has a problem that the magnitude of birefringence easily changes with changes in the surrounding environment. The influence mainly due to fluctuations in humidity is large. When the humidity is high, water molecules enter the gaps between the obliquely deposited films, and the birefringence becomes small. Conversely, birefringence increases as humidity decreases.

  As shown in FIG. 9, by sealing the obliquely deposited films 91 and 92 with the transparent cell 95, the magnitude of the birefringence of the obliquely deposited films 91 and 92 can be stabilized. However, the sealing method is not limited to this, and a method of forming a protective layer on the surface of the film or attaching a protective sheet may be used.

  As described above, by using the obliquely deposited films 91 and 92 as elements for shifting the path of the light according to the polarization direction by the birefringence effect, the economical efficiency of the apparatus is improved as compared with the case where the quartz plate is used. it can.

(Embodiment 8)
FIG. 10 shows a main part of an imaging apparatus according to Embodiment 8 of the present invention. The imaging apparatus according to the present embodiment includes an optical system 100 having a first crystal plate 101, a second crystal plate 102, and a liquid crystal panel 103 disposed therebetween. In the fifth embodiment (see FIG. 6), the first crystal plate 61 and the second crystal plate 62 have the optical axes A61 and A62 that are plane-symmetric with respect to the liquid crystal panel 63. In the embodiment, the optical axis A101 of the first crystal plate 101 and the optical axis A102 of the second crystal plate 102 are parallel to each other. The rest is the same as the imaging device of the fifth embodiment.

  In the present embodiment, when the drive voltage applied to the liquid crystal panel 103 is off, the two light beams separated by the first crystal plate 101 pass through a path indicated by a broken line, and thus there is one on the solid-state image sensor 65. A subject image is formed. In this case, the signal information regarding the light incident on each pixel of the solid-state image sensor 65 is taken in as it is, and the data is accumulated as the first image information.

  On the other hand, when the driving voltage applied to the liquid crystal panel 103 is on, the two light beams separated by the first crystal plate 101 form two subject images that overlap each other on the solid-state image sensor 65. To do. These two subject images when the drive voltage is on are formed at positions that are separated from each other subject image when the drive voltage is off by the same distance D in the vertical direction of the paper surface of FIG.

  As described in the fifth embodiment, image information (second image information) on one of the subject images is obtained from the image information on the two duplicated subject images obtained when the drive voltage is turned on. It is reproduced and superimposed on the first image information when the drive voltage is off. Thus, high-resolution image information having twice the number of pixels of the solid-state image sensor 65 can be obtained.

  In the first, second, fourth, fifth, sixth and eighth embodiments, the quartz plate is used as the element having the birefringence effect. However, the present invention is not limited to this, and any element having the birefringence effect may be used. Alternatively, an element using the electric birefringence effect (Kerr effect) or an element using the magnetic birefringence effect may be used.

  In Embodiments 1 to 8 above, the pair of crystal plates and the pair of obliquely deposited films disposed on both sides of the liquid crystal panel have the same thickness and are arranged so that the optical axis is in a predetermined direction. The present invention is not limited to this, and the optical axis direction, thickness, refractive index, and the like can be appropriately adjusted as long as the path of the light beam in a specific polarization direction can be shifted by the same amount.

  In the first to eighth embodiments, the liquid crystal panel is used as an element for rotating the polarization direction. However, a Pockels cell made of a crystal having an electro-optic effect may be used.

  The application field of the present invention is not particularly limited, but can be applied to, for example, a small camera module.

It is a block diagram which shows the imaging device which concerns on Embodiment 1 of this invention. (A) is the figure which showed the state in which one to-be-photographed image was imaged on the solid-state image sensor at the time of the applied voltage to a liquid crystal panel being ON in the imaging method which concerns on Embodiment 1 of this invention, (B). In the imaging method which concerns on Embodiment 1 of this invention, when the voltage applied to a liquid crystal panel is OFF, it is the figure which showed the state in which the two to-be-photographed object images were imaged on the solid-state image sensor. It is a block diagram which shows the imaging device which concerns on Embodiment 2 of this invention. It is a block diagram which shows the imaging device which concerns on Embodiment 3 of this invention. It is a block diagram which shows the imaging device which concerns on Embodiment 4 of this invention. It is a block diagram which shows the imaging device which concerns on Embodiment 5 of this invention. (A) is the figure which showed the state in which one to-be-photographed image was imaged on the solid-state image sensor at the time of the applied voltage to a liquid crystal panel being ON in the imaging method which concerns on Embodiment 5 of this invention, (B). In the imaging method which concerns on Embodiment 5 of this invention, it is the figure which showed the state in which the two to-be-photographed object images on the solid-state image sensor were imaged when the applied voltage to a liquid crystal panel is OFF. It is a block diagram which shows the imaging device which concerns on Embodiment 6 of this invention. It is a block diagram which shows the imaging device which concerns on Embodiment 7 of this invention. It is a block diagram which shows the imaging device which concerns on Embodiment 8 of this invention. It is a principle figure of the imaging device which performs the conventional pixel shift method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical system 11 1st crystal plate 12 2nd crystal plate 13 Liquid crystal panel 14 Voltage drive part 15 Solid-state image sensor 22 Subject image 23 when liquid crystal panel drive voltage is ON Subject image 23 when liquid crystal panel drive voltage is OFF 25 pixels 30A 1st optical system 30B 2nd optical system 31 1st crystal plate 32 2nd crystal plate 33 1st liquid crystal panel 34 Voltage drive part 35 3rd crystal plate 36 4th crystal plate 37 2nd liquid crystal panel 40 Optical system 41 1st diagonal Deposition film 42 Second oblique deposition film 43 Liquid crystal panel 45 Transparent cell 50 Optical system 51 First crystal plate 52 Second crystal plate 53 Liquid crystal panel 60 Optical system 61 First crystal plate 62 Second crystal plate 63 Liquid crystal panel 64 Voltage drive unit 65 Solid-state image sensor 72 Subject image 73 when liquid crystal panel drive voltage is ON 73, 74 Subject image when liquid crystal panel drive voltage is OFF 75 Liquid crystal panel Area 76, 76 area when liquid crystal panel drive voltage is OFF 80A first optical system 80B second optical system 81 first crystal plate 82 second crystal plate 83 first liquid crystal panel 84 voltage drive unit 85 third Crystal plate 86 Fourth crystal plate 87 Second liquid crystal panel 90 Optical system 91 First obliquely deposited film 92 Second obliquely deposited film 93 Liquid crystal panel 95 Transparent cell 100 Optical system 101 First crystal plate 102 Second crystal plate 103 Liquid crystal panel 111 Polarizer 112 Liquid crystal panel 113 Crystal plate

Claims (12)

An imaging method for obtaining a high-resolution image by temporally changing the relative positional relationship between a subject image formed on a solid-state image sensor and the pixels of the solid-state image sensor by an odd multiple of half the arrangement pitch of the pixels. There,
A first time zone in which light from a subject is separated into a plurality of lights having different polarization directions and then combined to form one subject image on the solid-state image sensor, and light from the subject is polarized. Are temporally switched to a second time zone in which a plurality of different images of light are separated from each other, and a plurality of subject images overlapping each other on the solid-state imaging device are formed.
Obtaining first image information about the one subject image based on signal information related to light incident on each pixel of the solid-state imaging device in the first time zone;
Calculating using signal information related to light incident on each pixel of the solid-state imaging device in the second time zone, and obtaining second image information about one of the plurality of subject images;
A high-resolution image of the subject is obtained using the first image information and the second image information.   The imaging method according to claim 1, wherein the second image information is obtained using signal information from a pixel on which only one of the plurality of subject images is formed. Extracting an area composed of a plurality of adjacent pixels from which equivalent signal information was obtained in the first time zone,
Of the signal information in the second time zone immediately after the first time zone, assuming that the signal information of the plurality of pixels in the area have the same value, the signal information in the second time zone The imaging method according to claim 1, wherein the second image information is obtained by calculating. The first transparent element and the second transparent element that shift the path of the light according to the polarization direction due to the birefringence effect, and the on / off of the voltage applied between the first transparent element and the second transparent element. A first optical system comprising a first liquid crystal panel that rotates transmitted light in response to turning off;
A solid-state image sensor;
First voltage control means for controlling a voltage applied to the first liquid crystal panel;
An imaging device in which light from a subject passes through the first optical system and is imaged as a subject image on the solid-state imaging device,
By switching on / off of the voltage applied to the first liquid crystal panel, one subject image and a first subject image and a second subject image that overlap each other on the solid-state image sensor alternately An imaging device characterized in that an image is formed. The first transparent element separates light from the subject into two polarized lights having different polarization directions, and separates the path of the two polarized lights by a distance D;
The first liquid crystal panel rotates the polarization direction of the two polarized lights emitted from the first transparent element by 0 degrees or 90 degrees according to an applied voltage,
The second transparent element shifts one path of the two polarized lights emitted from the first liquid crystal panel in accordance with the polarization direction thereof, to match the paths of the two polarized lights, or Expanding the path spacing of the two polarized lights to a distance of 2D;
The imaging device according to claim 4, wherein the solid-state imaging element reads a light intensity distribution formed by the two polarized lights emitted from the second transparent element.   Using the light intensity distribution formed by the two polarized lights whose path intervals are expanded to a distance 2D, a light intensity distribution by only one of the two polarized lights is obtained, and the light intensity distribution, 6. The imaging apparatus according to claim 5, further comprising a signal processing circuit obtained by calculating a light intensity distribution of the image of the subject using a light intensity distribution formed by the two polarized lights whose paths are matched. . Furthermore,
The third transparent element and the fourth transparent element that shift the path of the light beam according to the polarization direction by the birefringence effect, and disposed between the third transparent element and the fourth transparent element. A second optical system comprising a second liquid crystal panel that rotates transmitted light according to turning off;
Second voltage control means for controlling a voltage applied to the second liquid crystal panel,
Light from a subject passes through the first optical system and the second optical system and is imaged as a subject image on the solid-state image sensor,
By switching on / off the voltages applied to the first liquid crystal panel and the second liquid crystal panel, the first subject image and the first object at different positions in the first direction on the solid-state image sensor. The imaging apparatus according to claim 4, wherein the subject image and the second subject image, and the third subject image and the fourth subject image at different positions in a second direction different from the first direction are sequentially formed.   The imaging device according to claim 4, wherein the first transparent element and the second transparent element are metal oxide films deposited obliquely.   The imaging apparatus according to claim 7, wherein the third transparent element and the fourth transparent element are metal oxide films deposited obliquely.   The imaging apparatus according to claim 4, wherein the first liquid crystal panel is a twisted nematic liquid crystal panel.   The imaging apparatus according to claim 7, wherein the second liquid crystal panel is a twisted nematic liquid crystal panel.   The imaging device according to claim 4, wherein the solid-state imaging device is a MOS sensor.

Images