JP2013110538A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device having high-resolved pixels.SOLUTION: An image pickup device 10 comprises: stacked elements 100a, 100b, 100c, 100d for extracting signals corresponding to storage charges from each of photosensitive sections 101 arranged in tetragonal or hexagonal arrangements on the X, Y axis planes in parallel with the z axis and outputting them; and a liquid crystal element 106 provided on the element 100a having a photosensitive section 101 in the stacked element and forming pixels according to an amount of change of storage charges due to light shielding in each of divided regions by dividing each photosensitive section 101 into the regions by a predetermined division number by monitoring a light shielding part 110 smaller than the photosensitive section 101 for light-shielding in a part of region for each of photosensitive sections, within a region of the photosensitive section 101.

Description

  The present invention relates to the technical field of image pickup devices, and more particularly to an image pickup device having high-resolution pixels.

  In recent years, there has been a significant demand for higher resolution imaging devices. So far, for example, an image sensor having 32 million pixels corresponding to Super Hi-Vision has been realized. However, the required level of higher resolution in the future is even higher. For example, the required standard of resolution in imaging of three-dimensional information using integral photography (IP) is more than two to three digits. In this case, considering the realistic size of the image sensor, the size of one pixel is 1 μm square or less.

  As a conventional technique for increasing the resolution of an image pickup device, there is a method of reducing the size of one pixel including a photosensitive portion, a charge transfer portion or an amplification portion and increasing the number of pixels provided in the image pickup device plane. In this case, as the pixel size is reduced, the area of the photosensitive portion is reduced, and the amount of charge that can be accumulated per unit time is reduced and the S / N ratio is reduced. Since peripheral circuits such as these are provided in the pixel and a wiring is provided between the pixels, it is difficult to provide a sufficiently large photosensitive portion. For these reasons, sufficient imaging performance cannot be realized when the pixel size is 1 μm square or less.

  Therefore, in order to reduce the area occupied by the amplification unit or wiring provided in the pixel and increase the area of the photosensitive unit, the functions of the photosensitive unit, the charge transfer unit or the amplification unit are produced on separate element planes, There has been proposed an image pickup device in which these are stacked by a joining technique such as plasma processing, and signals are output in parallel in the Z-axis direction of each pixel (see, for example, Patent Document 1, Non-Patent Documents 1 and 2). An example of a stacked imaging device manufactured using such a joining technique is shown in FIG. In the image sensor 100 shown in FIG. 10, light received by the photosensitive unit 101 is converted into electric charges by photoelectric conversion and accumulated. A signal corresponding to this accumulated charge is sent to the amplifying unit 102 via the wiring 105, then sent to the signal processing unit 103, stored in the storage unit 104, and finally a signal is output from the output unit (not shown). Is output. As described above, the functions of the photosensitive unit 101, the amplifying unit 102 (or the charge transfer unit), the signal processing unit 103, the storage unit 104, and the like are manufactured on different element planes (illustrated 100a, 100b, 100c, and 100d). The imaging element 100 is formed by forming the wiring 105 by a bonding technique and laminating the elements 100a, 100b, 100c, and 100d.

  As a result, the proportion of the photosensitive portion in the area of one pixel can be significantly increased, and the S / N ratio can be increased even when the number of pixels increases and the pixels become smaller.

International Publication No. 2003/041174

Kurino et al., Intelligent image sensor chip with three dimensional structure, IEDM Technical Digest.International Washington, DC, USA, Dec. 5-8, 1999, pp. 879-882 Lee et al., Development of Three-Dimensional Integration Technology for Highly Parallel Image-Processing Chip, Japanese Journal of Applied Physics (JJAP), Vol. 39 Part1 (2000), No. 4B, pp. 2473-2477

  However, when the resolution of the imaging device is increased by the joining technique disclosed in Patent Literature 1 and Non-Patent Literatures 1 and 2, the resolution limit is determined by the joining error of each of the devices 100a, 100b, 100c, and 100d. . FIG. 11 and FIG. 12 are explanatory diagrams of factors that determine the resolution of a multilayer imaging device manufactured using a bonding technique. Referring to FIG. 11, for example, consider a case where the element 100a in which the photosensitive portion 101 is disposed and the element 100b in which the amplification portion 102 is disposed are joined. The details of the dotted line frame indicated by A in FIG. 11 are shown in FIG. Referring to FIG. 12, since the photosensitive portion 101 and the amplifying portion 102 are formed for each pixel, if the junction error exceeds the pixel size, the wiring 105 extending from the photosensitive portion 101 is not connected to the amplifying portion 102 immediately below. It will be.

  Even if the elements 100a, 100b, 100c, and 100d are joined by a joining process such as a plasma process using an infrared microscope and image processing, which are considered to have the highest accuracy at present, the maximum error is about ± 0.5 μm. Is done. Therefore, as shown in FIGS. 11 and 12, when the pixel size is 1 μm square or less, it is difficult to manufacture because the accuracy at the time of stacking is insufficient. That is, even if this bonding technique is used, it is difficult to form an image sensor having a pixel size of 1 μm square or less.

  An object of the present invention is to provide an imaging device having pixels with high resolution (for example, a pixel size of 1 μm square or less).

  In order to solve the above-described problems, the image sensor of the present invention extracts and outputs signals corresponding to accumulated charges in parallel in the Z-axis direction from each photosensitive unit arranged in a square or hexagon on the X and Y axis planes. And a single light-shielding element having an area smaller than the area of the photosensitive part for shielding light in a partial area with respect to each photosensitive part. A liquid crystal element that divides the photosensitive portion by a predetermined number of divisions by scanning the portion within the region of the photosensitive portion, and forms a pixel by the amount of change in accumulated charge due to light shielding in each divided region; It is characterized by providing.

  As a result, for a photosensitive portion having a size that can be produced by stacking, a light-shielding portion having a smaller size is scanned within the region of the photosensitive portion to extract a signal corresponding to a pixel, so that an existing imaging is performed. The resolution can be higher than that of the element. Further, since the scanning of the light shielding part can be formed only by electrical control, the size and position of the divided area of the photosensitive part can be freely changed, and the degree of freedom of imaging can be increased.

  In the imaging device of the present invention, the amount of change in the accumulated charge due to the light shielding is based on a signal corresponding to the accumulated charge obtained without shielding the photosensitive portion, and a signal corresponding to the accumulated charge based on the reference. And a signal corresponding to the accumulated charge obtained by light shielding by the light shielding portion.

  As a result, the pixel signal is formed with reference to a signal corresponding to the accumulated charge obtained without shading the photosensitive portion, so that a stable pixel signal can be obtained for each imaging.

  In the imaging device of the present invention, the amount of change in the accumulated charge due to the light shielding is normal for the signal corresponding to the accumulated charge obtained in the first accumulation time without shielding the photosensitive part in the first accumulation time. The second accumulation time with respect to the normalized signal corresponding to the accumulated charge based on the standardized signal and the signal corresponding to the accumulated charge obtained by shading with the light-shielding part in the second accumulation time It is characterized in that it is the amount of change of accumulated charge with time obtained from the difference from the signal normalized by.

  As a result, it is possible to individually set the accumulation time in the signal corresponding to the accumulated charge obtained without shading the photosensitive part and the accumulation time at the time of shading acquired as a pixel signal. The degree of freedom of control of the image sensor can be increased. For example, as an imaging mode, a still image mode, a moving image mode, a multiple shooting mode, or the like can be considered. To illustrate the control for each imaging mode, in the still image mode, a normalized signal corresponding to the reference accumulated charge is acquired in advance or at the start of imaging, and a signal corresponding to the accumulated charge due to light shielding is continuously obtained. Can be imaged. In the moving image mode, imaging can be performed by alternately obtaining and subtracting a normalized signal corresponding to the reference accumulated charge and a signal corresponding to the accumulated charge due to light shielding. In the multiple imaging mode, a normalized signal corresponding to the reference accumulated charge is acquired in advance, and a signal corresponding to the accumulated charge due to light shielding is continuously acquired, and then multiplexed and imaged. it can.

  In the image pickup device of the present invention, the area of the one light-shielding portion is ½ or less of the area of the one photosensitive portion.

  As a result, the resolution can be increased at least twice as much as that of an existing image sensor determined by the size of the photosensitive portion.

  In the imaging device of the present invention, the stacked element includes a first element in which the photosensitive portion is arranged squarely or hexagonally on the X and Y axis planes, and each of the photosensitive portions through scanning of the light shielding portion. A second element in which a storage unit for storing a signal corresponding to the accumulated charge obtained by receiving light as a pixel signal is arranged squarely or hexagonally on the X and Y axis planes, and each pixel signal stored in the storage unit And a third element in which a signal processing unit that reads out and outputs the predetermined region in the row-order arrangement order is arranged squarely or hexagonally on the X- and Y-axis planes.

  As a result, pixel signals obtained in the scanning order of the light-shielding portion can be read out and output in the order in which the photosensitive regions are divided in the row direction, so that post-processing of the pixel signals output from the image sensor is easy. Become.

  In the image pickup device of the present invention, the signal processing unit shields the photosensitive unit with respect to a signal corresponding to the accumulated charge obtained by receiving each of the photosensitive units through scanning of the light shielding unit. The signal corresponding to the accumulated charge obtained at the first accumulation time without using the signal normalized at the first accumulation time as a reference, the normalized signal corresponding to the accumulated charge based on the reference, and the second accumulation The signal corresponding to the accumulated charge obtained by light shielding by the light shielding unit over time is differentiated from the signal normalized by the second accumulation time, and the temporal change amount of the accumulated charge due to the light shielding is stored as the pixel signal. It has the means to memorize | store in a part.

  Here, both the first accumulation time and the second accumulation time can be the same constant time, or can be different times. The second accumulation time when obtaining a signal corresponding to the accumulated charge due to light shielding may also be individually different accumulation times. For example, normalization is performed by dividing the signal corresponding to the accumulated charge by the accumulation time. Can do.

  According to the present invention, it is possible to provide an imaging device having high-resolution pixels (for example, a pixel size of 1 μm square or less). In particular, it is possible to significantly reduce the insensitive area between pixels that has occurred in the conventional imaging device, and to improve the S / N by comparing the same pixel size. Furthermore, it is possible to increase the degree of freedom of imaging according to the use of the divided areas of the photosensitive part and the reading order of pixel signals in the photosensitive part.

It is the schematic of the image pick-up element of one Embodiment by this invention. It is a figure explaining the positional relationship and operation | movement at the time of each light-shielding part scanning about each of arbitrary four photosensitive parts in the image pick-up element of one Embodiment by this invention. (A), (b), (c), (d), (e) is a figure which shows the operation example in the image pick-up element of one Example by this invention. It is a figure which shows an example of the output signal for every area | region obtained by dividing | segmenting one photosensitive part in the image pick-up element of one Example by this invention. It is a figure explaining the normalization process of the output signal for every area | region obtained by dividing | segmenting one photosensitive part in the image pick-up element of one Example by this invention. In each of the adjacent four photosensitive portions in the image pickup device according to the embodiment of the present invention, rearrangement is performed so that the signal for each region obtained by dividing the photosensitive portion becomes a signal output in the row direction. It is a figure explaining an example. It is a block diagram which shows an example of the signal processing part in the image pick-up element of one Embodiment by this invention. It is a figure which shows the operation example of the signal processing part in the image sensor of one Embodiment by this invention. It is a figure which shows another example of operation | movement of the signal processing part in the image sensor of one Embodiment by this invention. It is a figure which shows the example of the laminated type image pick-up element produced using the joining technique in a prior art. It is explanatory drawing about the factor which determines the resolution of the laminated type image pick-up element produced using the joining technique in a prior art. It is explanatory drawing of the joining error as a factor which determines the resolution of the laminated type image pick-up element produced using the joining technique in a prior art.

  Hereinafter, an image sensor according to an embodiment of the present invention will be described with reference to the drawings. It should be noted that the same constituent elements will be described with the same reference numerals.

  FIG. 1 is a schematic diagram of an image sensor 10 according to an embodiment of the present invention. The image sensor 10 of the present embodiment includes laminated elements 100a, 100b, 100c, and 100d as illustrated in FIG. 10 and a liquid crystal element 106.

  In the element 100a, the photosensitive portion 101 that outputs a signal corresponding to the accumulated charge obtained by receiving light is squarely arranged on the X and Y axis planes. In the element 100b, an amplifying unit 102 that amplifies a signal corresponding to an accumulated charge obtained by receiving light by each of the photosensitive units 101 is squarely arranged on the X and Y axis planes. In the element 100d, a storage unit 104 that stores the amplified signal as each pixel signal via the signal processing unit 103 of the element 100c is arranged squarely on the X and Y axis planes. The element 100c outputs a signal processing unit 103 that reads out and outputs each pixel signal stored in the storage unit 104 in the order of arrangement in a row direction of a predetermined area obtained by dividing the photosensitive unit 101 by a light shielding unit 110 described later. The square is arranged on the top. The photosensitive unit 101, the amplification unit 102, the signal processing unit 103, and the storage unit 104, which are squarely arranged in each of the stacked elements 100a, 100b, 100c, and 100d, are connected via a wiring 105 (see FIG. 10). If the photosensitive unit 101, the amplifying unit 102, the signal processing unit 103, and the storage unit 104 are configured to extract and output in parallel in the Z-axis direction, they are arranged in six directions on the X and Y axis planes (that is, , A honeycomb-like arrangement). Further, the element 100b of the amplifying unit 102 is not necessarily provided depending on the application. Therefore, the signal output from the photosensitive unit 101 may be amplified or non-amplified as the “signal corresponding to the accumulated charge”.

  Therefore, similarly to the configuration illustrated in FIG. 10, these stacked elements 100a, 100b, 100c, and 100d extract and output signals corresponding to accumulated charges from each photosensitive portion 101 in parallel in the Z-axis direction. Composed. However, unlike the example described with reference to FIG. 10 as the prior art, in the present invention, the lamination having the photosensitive portion 101 having a relatively large size created within the accuracy that can be laminated regardless of whether or not the bonding technique is used. Even in the case of an element, a resolution higher than the resolution determined by the size of the photosensitive portion 101 can be obtained, that is, the resolution can be increased beyond the limit of the joining accuracy of the stacked elements 100a, 100b, 100c, and 100d in the imaging element. It is different in that.

  That is, in the present embodiment, the imaging element 10 uses a liquid crystal element 106 represented by a liquid crystal panel or the like, and scans the light shielding unit 110 by controlling the polarizing element that controls the polarization function of the liquid crystal element 106. FIG. 2 shows that for each of the four adjacent photosensitive portions 101-1, 101-2, 101-3, and 101-4, the light shielding portions 110-1, 110-2, 110-3, and 110-4 are respectively provided. It is a figure explaining the positional relationship and operation | movement at the time of scanning. In the present embodiment, one light shielding portion 110 divides one photosensitive portion 101 region into predetermined divided regions by the liquid crystal element 106 that scans within the one photosensitive portion 101 region, thereby forming pixels. Usually, the liquid crystal element 106 includes a vertical polarizing plate, an individual electrode substrate for each specific small region, a liquid crystal, a common electrode substrate for all regions, and a horizontal polarizing plate, and transmits and does not transmit light in the specific small region. Can be controlled. For this reason, in the image sensor 10 of the present embodiment, the scanning of the light shielding unit 110 can be realized by the liquid crystal element 106.

  For example, in order to obtain a high-resolution image sensor 10 corresponding to a pixel size of 1 μm square or less, the image sensor of the present embodiment can be used even when the photosensitive portion 101 has a size (for example, 4 μm square size) that can be manufactured by stacking stacked elements. 10, the liquid crystal element 106 shields a part of the photosensitive portion 101 with the light shielding portion 110, calculates the amount of light applied to the portion from the attenuation of the signal output due to the light shielding, and scans the light shielding portion 110 to scan the photosensitive portion 101. Since the amount of change in the accumulated charge in each divided region obtained by dividing this region is used as a pixel signal, the resolution obtained as image information can be increased more than the resolution determined by the size of the photosensitive portion 101.

  Therefore, in the image sensor 10 of the present embodiment, the light shielding unit 110 having a displacement amount of several μm to several tens of μm with a resolution of several nm with respect to one photosensitive unit 101 can be realized.

  More specifically, the positional relationship and operation of the photosensitive unit 101 and the light shielding unit 110 will be described. In FIG. 2, each of the light shielding portions 110-1, 110-2, 110-3, and 110-4 is a surface of each of the photosensitive portions 101-1, 101-2, 101-3, and 101-4. A state in which scanning is performed in the order indicated by the arrows is shown. Focusing on the photosensitive unit 101-1, the light shielding unit 110-1 moves so as to scan the surface of the photosensitive unit 101-1, and the light shielding unit 110-1 is located at a certain position of the photosensitive unit 101-1. Light passing through a region other than the light shielding unit 110-1 within the time is photoelectrically converted by the photosensitive unit 101-1, and a signal corresponding to the accumulated charge is amplified by the amplification unit 102 and output. Thereafter, the accumulated charge in the photosensitive portion 101-1 is reset, and then the light shielding portion 110-1 is moved to another location on the surface of the photosensitive portion 101-1, where the light shielding portion 110-1 is located at that location. Light passing through a region other than the light shielding unit 110-1 within the time is photoelectrically converted by the photosensitive unit 101-1, and a signal corresponding to the accumulated charge is amplified by the amplification unit 102 and output. By repeating this, it is possible to increase the resolution at the time of imaging, rather than the resolution determined by the four photosensitive units 101-1, 101-2, 101-3, and 101-4. In the example shown in FIG. 2, since the scanning example of the light shielding unit 110 that divides one photosensitive unit 101 into 64 parts is shown, it is possible to realize 64 times higher resolution, which is a problem of bonding accuracy in the prior art. The high-resolution image sensor 10 that could not be configured can be realized.

  Next, more specific examples of the image sensor 10 according to the present invention will be described.

(Example)
First, an image sensor 10 according to an embodiment of the present invention will be described. In the imaging device 10 of the present embodiment, the size of the photosensitive portion 101 is 4 μm square. In addition, a liquid crystal element 106 capable of partially shielding light of 0.5 μm square was used. The number of photosensitive portions 101 of the image sensor 10 of the present embodiment is 240 in the horizontal direction and 135 in the vertical direction. The distance from the liquid crystal element 106 to the element 100a in which the photosensitive portions 101 are arranged in the laminated element is set to 0.5 μm as a distance that does not scatter the light transmitted through the light shielding portion 110. The liquid crystal element 106 scans a part of the photosensitive portion 101 while being shielded by the light shielding portion 110. FIG. 3 shows an operation example in the image sensor 10 of one embodiment. FIG. 3 shows an example of divided regions obtained by dividing the photosensitive portion 101-1 shown in FIG. 2 into 64 portions by scanning with the light shielding portion 110-1. Each of the 64 divided areas corresponding to the pixels at the time of imaging is sequentially assigned a divided area in the X axis advance direction (left to right on the drawing), and further the Y axis advance direction (from top to bottom on the drawing). Divided areas are assigned sequentially. Accordingly, FIG. 3A shows a region 1 corresponding to the pixel at the time of imaging, FIG. 3B shows a region 2 corresponding to the pixel at the time of imaging, and FIG. Shows the region 3 corresponding to the pixel at the time of imaging, FIG. 3 (d) shows the region 16 corresponding to the pixel at the time of imaging, and FIG. 3 (e) corresponds to the pixel at the time of imaging. A region 57 is shown. In this way, the liquid crystal element 106 scans one light-shielding part 110 within the area of one photosensitive part 101, thereby dividing one photosensitive part 101 area into predetermined divided areas to form pixels. To do. The effective number of pixels increases by the ratio of the area of the photosensitive portion 101 to the light shielding area of the light shielding portion 110, and FIG. For example, even at the current technical level, by combining the 10 μm square photosensitive portion 101 with the 0.5 μm square light-shielding portion 110, the effective number of pixels can be increased by 400 times and high resolution can be achieved.

Next, an outline of the operation of the image sensor 10 according to an embodiment of the present invention will be described. FIG. 4 is a diagram illustrating an example of an output signal for each region obtained by dividing one photosensitive portion 101 in the image sensor 10 of the present embodiment. First, each photosensitive unit 101 receives light from the entire photosensitive unit 101 without shading, and the signal processing unit 103 measures a temporal change amount X (gradient of the graph) of the amount of charge gradually accumulated in the photosensitive unit 101 by photoelectric conversion. Thus, a signal corresponding to the reference accumulated charge is used. Thereafter, the liquid crystal element 106 is driven, and a part (region 1) of the photosensitive portion 101 is shielded from light for a certain period of time. This shielding, increase the accumulated charge amount is X-[Delta] X ₁ changes. Since this change ΔX ₁ is essentially equal to the amount of light received in the region 1, the output in the region 1 is accumulated in the storage unit 104 as ΔX ₁ . Next, a part of the photosensitive portion 101 (area 2) is shielded from light for a certain period of time. This shielding, increase the accumulated charge amount is X-[Delta] X ₂ changes. Since this change ΔX ₂ is essentially equal to the amount of light received in the region 2, the output in the region 2 is accumulated in the storage unit 104 as ΔX ₂ . By repeating this process 64 times as shown in FIG. 3, for example, by measuring the amount of light received by each light shielding unit 110, it is possible to increase the resolution by 8 times in length and 8 times in width. In FIG. 4, for convenience of explanation, as an example of resetting the photosensitive unit 101 for each predetermined number of areas, an example in which accumulated charge amounts in “no light shielding”, “area 1”, and “area 2” are accumulated. However, it is a matter of course that the photosensitive portion 101 may be reset for each scan of “no light shielding”, “region 1”, and “region 2”.

  When the liquid crystal element 109 is used, the light shielding unit 110 can be scanned without physically moving the element. Further, since the pixel is formed by scanning the light shielding unit 110 having a certain shape as a time change amount with respect to a signal corresponding to the reference accumulated charge, the pixel shape due to the strict light shielding ability in the light shielding unit 110 is a problem. A stable captured image can be obtained without any problem.

FIG. 5 is a diagram for explaining normalization processing of output signals for each region obtained by dividing one photosensitive portion 101 in the image sensor 10 of the present embodiment. In FIG. 5, for convenience of explanation, as an example of resetting the photosensitive unit 101 for each predetermined number of areas, an example in which accumulated charge amounts in “no light shielding”, “area 1”, and “area 2” are accumulated is illustrated. Of course, the photosensitive unit 101 may be reset for each scan of “no light shielding”, “area 1”, and “area 2”. In FIG. 5, light is not shielded from time T ₁ to time T _2, and the time change of the entire photosensitive portion 101 is defined as Y / (T ₂ −T ₁ ) from the charge amount Y accumulated at this time. 103 measures. Next, the liquid crystal element 106 shields the region 1 from time T ₂ to T ₃ . If the amount of charge stored during of _{T 3} from the time _{T 2} and _{Y 1,} the time change is a _{Y 1 / (T 3 -T 2} ). That is, the amount of charge that the photosensitive portion 101 originally receives and accumulates in the region 1 is Y / (T ₂ −T ₁ ) −Y ₁ / (T ₃ −T ₂ ), and a signal value corresponding to this amount of charge is stored. Stored in the unit 104. Next, the liquid crystal element 106 to shield the region 2 from the time _{T 3} toward _{T 4.} If the amount of charge stored during this time _{T 3} from _{T 4} and _{Y 2,} time variation becomes _{Y 2 / (T 4 -T 3} ). That is, the amount of charge that the photosensitive portion 101 originally receives and accumulates in the region 2 is Y / (T ₂ −T ₁ ) −Y ₂ / (T ₄ −T ₃ ), and a signal value corresponding to this amount of charge is stored. Stored in the unit 104. By repeating this, a signal corresponding to the time change amount of each accumulated charge in the regions 1 to 64 is stored in the storage unit 104. FIG. 6 is an explanatory diagram for rearranging the signals corresponding to the accumulated charges in the image sensor 10 of this embodiment to the signal output in the row direction. As shown in FIG. 6, the signal processing unit 103 converts the signal corresponding to the time change amount of each accumulated charge stored in the storage unit 104 to a signal output in the row direction similar to the conventional image sensor, and finally To the output unit (not shown). As a result, all the photosensitive units 101 are divided into 64, so that the number of the photosensitive units 101 (240 in the horizontal direction and 135 in the vertical direction) is increased in resolution, and a high-definition output of 1920 and 1080 in the horizontal direction can be obtained. As another example, when all the photosensitive units 101 are divided into 1024, the number of photosensitive units 101 (240 in horizontal and 135 in vertical) is divided into 1024, and the signal output of the number of Super Hi-Vision pixels (horizontal 7680 and vertical 4320) is output. Can be obtained.

  In the case of the imaging device 10 of the present embodiment, the total time of charge accumulation and transfer is (1/30) ÷ 64 if the time of one frame of the finally output video is 1/30 seconds. Division = 1/1920 seconds. An output signal for each region obtained by dividing one photosensitive portion 101 is obtained as an output signal at an individual pixel position. Signals corresponding to time-series accumulated charges obtained from the respective photosensitive units 101 are amplified by the respective amplification units 102 and then stored in the respective storage units 104 via the respective signal processing units 103. Further, as illustrated in FIG. 6, each signal processing unit 103 reads out the signal stored in each storage unit 104 so as to correct the signal output in the row direction similar to that of the conventional image sensor 100, and outputs the output unit. (Not shown). In the signal processing unit 103, a register synchronized with an external clock (CLK) in advance so as to obtain a signal output in the row direction similar to that of the conventional image sensor 100 with respect to storage and readout of signals for each predetermined region in the storage unit 104. A circuit may be configured.

  Here, it can be set as the following structures about the above-mentioned Example.

(1) Although silicon photo-diode is generally used as the photosensitive portion 101, a photoelectric conversion material having a photosensitizing action such as amorphous selenium or amorphous silicon may be used.

(2) The photosensitive unit 101, the amplifying unit 102, and the signal processing unit 103 may be a pixel complete parallel type in which one photosensitive unit 101 is provided for each photosensitive unit 101, for example, one amplifying unit 102 and signal for every four photosensitive units 101. A partial parallel type processing unit 103 may be used.

(3) The image sensor 10 is not limited to a CMOS image sensor, and may be a CCD image sensor. In the case of a CCD image pickup device, for example, the above-described laminated element including the photosensitive unit 101, the amplifying unit 102, the signal processing unit 103, and the storage unit 104 is arranged with the photosensitive unit, the charge transfer unit, the frame memory, and the signal processing unit, respectively. A laminated element can be obtained.

(4) The light shielding unit 110 may be constantly moved without repeating the stationary and moving. In the case of a structure that always moves, the resolution is determined by the cycle of transferring charges. For example, when moving the light shielding unit 110 in the X-axis direction or the Y-axis direction on the surface of the 4 μm square photosensitive unit 101 and transferring the accumulated charge four times during the movement period, the 4 μm square determined by the photosensitive unit 101 is used. A resolution of 2 μm can be obtained both vertically and horizontally.

(5) The charge accumulated in each area may be reset each time, or may continue to be accumulated without being reset to a predetermined number of areas. In general, the larger the total amount of accumulated charges, the higher the S / N ratio, and the latter may be advantageous.

(6) The distance between the liquid crystal element 106 and the element 100a of the photosensitive portion 101 is preferably close in order to suppress the influence of light wraparound. More preferably, contact is better.

(7) In the image pickup device 10 according to the present invention, the color filter is located at a position corresponding to a region obtained by dividing the surface of the photosensitive portion 101 by scanning the light shielding portion 110 between each photosensitive portion 101 and the liquid crystal element 106. May be provided. Therefore, it is possible to configure the image sensor 10 according to the present invention regardless of multicolor or single color.

(8) In the imaging device 10 according to the present invention, the shape of the light shielding unit 110 may be a square, a rectangle, a circle, an ellipse, a rhombus, or a polygon.

  Next, an example of the configuration and operation of the signal processing unit 103 in the image sensor 10 of the present embodiment will be described with reference to FIGS.

  FIG. 7 shows a configuration example of the signal processing unit 103 in the image sensor 10 of the present embodiment. FIG. 8 shows an operation example of the signal processing unit 103 in the image sensor 10 of the present embodiment. FIG. 9 shows another operation example of the signal processing unit 103 in the image sensor 10 of the present embodiment. It should be noted that FIGS. 7 to 9 show only specific parts according to the present invention. Referring to FIG. 7, the signal processing unit 103 includes a reset signal generation unit 1031, a scanning control signal generation unit 1032, an output signal arrangement control unit 1033, a sampling signal generation unit 1034, a sample / hold (S / H). ) Units 1035 and 1036 and a subtracting unit 1037.

  The reset signal generation unit 1031 generates a reset signal RS for resetting charge accumulation in each photosensitive unit 101 in synchronization with the external clock (CLK), and supplies the reset signal RS to the photosensitive unit 101.

  The scanning control signal generation unit 1032 generates a scanning control signal SC for scanning the light shielding unit 110 on the surface of the photosensitive unit 101 in synchronization with the external clock (CLK) and supplies the scanning control signal SC to the liquid crystal element 106.

  The output signal arrangement control unit 1033 synchronizes with the external clock (CLK), and the signal corresponding to the time-series accumulated charge obtained from each photosensitive unit 101 stored in the storage unit 104 is the same as that of the conventional image sensor 100. The arrangement of the output signals is controlled so as to read out the signal in the row direction and output it to the output unit (not shown).

  The sampling signal generator 1034 is synchronized with the external clock (CLK), and a sampling signal SPr for sampling on the basis of a signal corresponding to the accumulated charge obtained in the first accumulation time without shielding the photosensitive unit 101 from light. , The light-sensitive portion 101 is shielded by the light-shielding portion 110, and a sampling signal SPs for sampling a signal corresponding to the accumulated charge obtained in the second accumulation time is generated, and each sample / hold (S / H) portion 1035 is generated. , 1036.

  The sample / hold (S / H) unit 1035 uses the sampling signal SPr to sample a signal corresponding to a reference accumulated charge obtained at a predetermined accumulation time (first accumulation time) without shading the photosensitive portion 101. And hold.

  The sample / hold (S / H) unit 1036 is a signal corresponding to the accumulated charge obtained by being shielded by the light shielding unit 110 for a predetermined accumulation time (second accumulation time) by the light shielding unit 110 based on the sampling signal SPs. Is sampled and held.

  The subtracting unit 1037 normalizes the signal corresponding to the reference accumulated charge obtained from the sample / hold (S / H) unit 1035 by dividing the signal by the first accumulation time, and samples / holds ( S / H) The signal corresponding to the accumulated charge obtained by shielding from the light shielding unit 1036 is normalized by the second accumulation time, and the signal corresponding to the standard accumulated charge is normalized. The difference between the signal and a signal normalized with respect to the signal corresponding to the accumulated charge obtained by shading by the light shielding unit 110 is calculated, and the time change amount of the accumulated charge obtained from this difference is used as an output signal (pixel signal). , Temporarily stored in the storage unit 104. The temporarily stored output signals are rearranged when output to the output unit (not shown) by the output signal arrangement control unit 1033 (see FIG. 6).

  FIG. 8 shows a case in which a normalized signal corresponding to the reference accumulated charge is acquired in advance or at the start of imaging, and a signal corresponding to the accumulated charge due to light shielding is continuously acquired. An example of the operation timing of the signal processing unit 103 is shown. An example in which the interval of the reset signal RS is equal is shown, and the light shielding unit 110 is scanned for each divided region on the surface of the photosensitive unit 101 due to the generation of the scanning control signal SC. After the generation of the sampling signal SPr, a difference signal obtained by subtracting each signal corresponding to the accumulated charge obtained from the photosensitive unit 101 sampled and held by the sampling signal SPs generated successively is subtracted by the subtracting unit 1037 for each divided region. Output signal (pixel signal).

  FIG. 9 shows an example of the operation timing of the signal processing unit 103 shown in FIG. 7 when the normalized signal corresponding to the reference accumulated charge and the signal corresponding to the accumulated charge due to light shielding are alternately and continuously acquired. Is shown. An example in which the interval of the reset signal RS is equal is shown, and the light shielding unit 110 is scanned for each divided region on the surface of the photosensitive unit 101 due to the generation of the scanning control signal SC. The difference signal obtained by subtracting the signals corresponding to the accumulated charges obtained from the photosensitive portion 101 sampled and held by the alternately generated sampling signals SPr and SPs is output by the subtractor 1037 as an output signal (pixel signal) for each divided region. ) Can be obtained.

  In the examples shown in FIGS. 8 and 9, the accumulation time for normalizing the signal corresponding to the reference accumulated charge and the signal corresponding to the accumulated charge obtained by shading by the light shielding unit are normalized. As for the accumulation time for doing this, since they are all the same constant time, there is no need for normalization calculation as a function of time. For this reason, the difference between the signal corresponding to the accumulated charge based on the reference and the signal corresponding to the accumulated charge obtained by light shielding by the light shielding unit 110 is treated as a pixel signal defined by the amount of change in accumulated charge due to light shielding. be able to.

  In the example shown in FIGS. 8 and 9, an example in which the interval of the reset signal RS is equal is shown. However, the interval is not necessarily equal, and the scanning of the aperture 110 is associated with the reset timing in advance. The photosensitive unit 101 may be reset intermittently according to the time pattern. However, in this case, it is preferable to divide the output signal obtained for each divided region by the accumulation time corresponding to the scanning of the aperture 110 according to this time pattern, and normalize the pixel signal. Such a division function according to the time pattern may be configured as a part of the signal processing unit 103 in the image sensors 10 and 10b, or may be realized as a subsequent process for the output signals from the image sensors 10 and 10b. .

  Although specific examples have been described in the above embodiments, the present invention is not limited to these embodiments. For example, a laminated element in which elements of the photosensitive unit and the signal processing unit are stacked has been described as an example. However, an element in which the photosensitive unit 101 and other functional units (such as the amplification unit 102 and the signal processing unit 103) are arranged on a plane is used. It can also be applied to.

  According to the present invention, it is possible to provide an image sensor having a high-resolution pixel (for example, a pixel size of 1 μm square or less) that has been difficult to manufacture with the prior art. It is useful for the application of a stereoscopic imaging camera.

DESCRIPTION OF SYMBOLS 10 Image sensor which concerns on this invention 100 Conventional image sensor 100a, 100b, 100c, 100d Each element of a laminated element 101,101-1,101-2,101-3,101-4 Photosensitive part 102 Amplifying part 103 Signal processing part 104 Storage unit 105 Wiring 106 Liquid crystal element 110, 110-1, 110-2, 110-3, 110-4 Light shielding unit 1031 Reset signal generation unit 1032 Scan control signal generation unit 1033 Output signal array control unit 1034 Sampling signal generation unit 1035 , 1036 Sample / hold (S / H) part 1037 Subtraction part

Claims (6)

A laminated element that extracts and outputs a signal corresponding to accumulated charge in parallel in the Z-axis direction from each photosensitive portion arranged in a square or hexagon on the X and Y axis planes;
One light-shielding portion that is provided for an element having a photosensitive portion in the laminated element and has an area smaller than the area of the photosensitive portion for shielding light in a partial region with respect to each photosensitive portion. A liquid crystal element that divides the photosensitive portion by a predetermined number of divisions by scanning within a region of the portion, and forms a pixel by a change amount of accumulated charge due to light shielding in each divided region;
An image pickup device comprising:   The amount of change in the accumulated charge due to the light shielding is obtained by shielding the signal corresponding to the accumulated charge based on the reference and the light shielding portion with reference to the signal corresponding to the accumulated charge obtained without shielding the photosensitive portion. The imaging device according to claim 1, wherein a difference from a signal corresponding to a stored charge to be generated is used.   The amount of change in the accumulated charge due to the light shielding is based on the signal normalized by the first accumulation time with respect to the signal corresponding to the accumulated charge obtained in the first accumulation time without shielding the photosensitive part. From the difference between the normalized signal corresponding to the accumulated charge and the signal normalized by the second accumulation time for the signal corresponding to the accumulated charge obtained by shielding the light with the light shielding portion in the second accumulation time The imaging device according to claim 2, wherein the amount of accumulated charge obtained is a time change amount.   4. The image pickup device according to claim 1, wherein an area of the one light-shielding portion is ½ or less of an area of the one photosensitive portion. 5.   The stacked element includes a first element in which the photosensitive portion is arranged squarely or hexagonally on the X and Y axis planes, and the accumulated charge obtained by receiving light at each of the photosensitive portions through scanning of the light shielding portion. A second element in which a storage unit that stores corresponding signals as respective pixel signals is arranged squarely or hexagonally on the X and Y axis planes, and a row direction of the predetermined region for each pixel signal stored in the storage unit 5. A signal processing unit that reads out and outputs the data in the order of the arrangement, and a third element arranged squarely or hexagonally on the X- and Y-axis planes. 5. Image sensor.   The signal processing unit can obtain a signal corresponding to the accumulated charge obtained by receiving light by each of the photosensitive units through scanning of the light shielding unit in a first accumulation time without shielding the photosensitive unit. With respect to a signal corresponding to the accumulated charge, the signal normalized by the first accumulation time is used as a reference, and the signal normalized by the reference accumulated charge is shielded from light by the light shielding unit at the second accumulation time. The signal corresponding to the accumulated charge obtained is differentiated from the signal normalized by the second accumulation time, and the storage unit has a means for storing the amount of time variation of the accumulated charge due to the light shielding as a pixel signal. The imaging device according to claim 5, wherein the imaging device is characterized.