JP2021002778A - Image sensor - Google Patents

Abstract

To provide an image sensor that can automatically switch different filters according to an imaging environment.SOLUTION: The image sensor includes a light-receiving element having a light receiving unit, an optical element disposed on the light receiving unit and having first, second, and third regions with different optical characteristics adjacent to each other, and a control mechanism for controlling into the first state in which the light receiving unit and the first region overlap, the second state in which the light receiving unit and the second region overlap, and the third state in which the light receiving unit and the third region overlap, by shifting the optical element. A first filter is provided in the second region. The third region is provided with a second filter different from the first filter.SELECTED DRAWING: Figure 1

Description

One embodiment of the present invention relates to an image sensor. In particular, one embodiment of the present invention relates to an image sensor provided with a movable filter having different optical characteristics.

In recent years, electronic devices equipped with a solid-state image sensor have become widespread. For example, electronic devices having a function for capturing a solid body, such as a mobile phone, a smartphone, a notebook personal computer, a tablet personal computer, a digital camera, a digital video camera, and an in-vehicle camera, are equipped with an image sensor. .. The image sensor converts the captured solid image into digital information. Based on the digital information converted and output by the image sensor, the captured solid image is stored in the storage device as electronic data.

In a general image sensor, a phenomenon occurs in which an captured image becomes pure white due to a sudden change in the amount of light (hereinafter, may be referred to as “blown out”). For example, when a car goes out of a tunnel, whiteout occurs due to external light such as sunlight incident on an image sensor mounted on an in-vehicle camera.

In order to deal with such a problem, there is known a technique for obtaining an antiglare effect by cutting light having a constant polarized light, such as sunlight incident from above. For example, a technique for obtaining an antiglare effect by using a polarizing filter is known. Conventionally, it has been common to attach a polarizing filter to a lens to obtain an antiglare effect, and it is necessary to manually move the polarizing filter in order for the polarizing filter to function. In order to save the trouble of manually moving the polarizing filter, for example, as in Patent Document 1, an image sensor having a configuration in which the polarizing filter is automatically operated has been developed.

Special Table 2012-513607

However, the technique described in Patent Document 1 merely controls turning the filter on and off, and can perform advanced filter switching such as automatically switching a different filter according to the imaging environment. There wasn't.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image sensor capable of automatically switching different filters according to an imaging environment.

In the image sensor according to the embodiment of the present invention, a light receiving element having a light receiving portion and a first region, a second region, and a third region arranged on the light receiving portion and having different optical characteristics are adjacent to each other. The arranged optical element and the optical element are shifted, the first state in which the light receiving portion and the first region overlap, the second state in which the light receiving portion and the second region overlap, and the light receiving portion and the said It has a control mechanism that controls a third state in which the third region overlaps. A first filter is provided in the second region, and a second filter different from the first filter is provided in the third region.

The first filter and the second filter may be polarizing filters having different polarization characteristics.

The optical element may further have a fourth region provided with a light blocking filter.

The control mechanism may include MEMS.

The optical element may further have a fifth region and a sixth region provided with ND filters having different densities.

The optical element includes a first optical element and a second optical element, and the first optical element and the second optical element are arranged so as to overlap each other in a plan view, and the first optical element has the first filter. The second optical element may have the second filter.

It further has a determination unit that executes the first determination based on the number of pixels indicating white in the captured image, and the determination unit determines that the number of pixels indicating white in the first determination exceeds the threshold value. In the case, the control mechanism superimposes a plurality of the first filters on the light receiving unit, and the determination unit is based on the number of pixels showing white in an image captured with the first filter overlapping the light receiving unit. When the second determination is executed and the determination unit determines in the second determination that the number of pixels showing white exceeds the threshold value, the control mechanism superimposes a plurality of the second filters on the light receiving unit. The determination unit executes a third determination based on the number of pixels showing white in the image captured with the second filter overlapping the light receiving unit, and based on the second determination and the third determination. The presence or absence of imaging abnormality may be determined.

According to one embodiment of the present invention, it is possible to provide an image sensor capable of automatically switching different filters according to an imaging environment.

It is a top view which shows the optical element and the light receiving element of the image sensor which concerns on one Embodiment of this invention individually. It is a top view which shows the optical element and the light receiving element of the image sensor which concerns on one Embodiment of this invention in a superposed state. It is sectional drawing which shows the outline of the image sensor which concerns on one Embodiment of this invention. It is a top view which shows the outline of the image sensor which concerns on one Embodiment of this invention. It is a top view of the state which the optical element of the image sensor which concerns on one Embodiment of this invention is shifted in the 1st direction with respect to a light receiving element. It is a top view of the state which the optical element of the image sensor which concerns on one Embodiment of this invention is shifted in the 2nd direction with respect to a light receiving element. It is a top view of the state which the optical element of the image sensor which concerns on one Embodiment of this invention is shifted in the 1st direction and the 2nd direction with respect to a light receiving element. It is a top view which shows the light receiving element and the optical element of the image sensor which concerns on one Embodiment of this invention individually. It is sectional drawing which shows the outline of the image sensor which concerns on one Embodiment of this invention. It is a top view which shows the light receiving element and the optical element of the image sensor which concerns on one Embodiment of this invention individually. It is a top view which shows the outline of the image sensor which concerns on one Embodiment of this invention. It is a circuit block diagram which shows the pixel circuit of the image sensor which concerns on one Embodiment of this invention. It is a figure which shows the operation flow in the image pickup abnormality determination of the image sensor which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The disclosure is just an example. That is, a configuration that can be easily conceived by a person skilled in the art by appropriately changing the invention while maintaining the gist of the invention is naturally included in the scope of the present invention. In order to clarify the explanation, the drawings may be schematically represented by the width, thickness, shape, etc. of each part as compared with the actual embodiment. However, these are merely examples and do not limit the interpretation of the present invention. Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be accompanied by the same reference numerals with uppercase alphabets, and detailed description thereof may be omitted as appropriate.

In the present specification and claims, when the aspect in which the second structure is arranged on the first structure is expressed, when it is simply described as "above" or "above", unless otherwise specified. Is when the second structure is arranged directly above the first structure so as to be in contact with the first structure, and when the second structure is placed above the first structure via yet another third structure. It is defined to include both when the body is placed and when it is placed. In the following description, the direction from the light receiving element to the optical element is referred to as "up" or "upward", and the opposite direction is referred to as "down" or "downward".

In the following description, a configuration in which a photoelectric conversion element in which an electromotive force is generated by light is used as the light receiving element will be illustrated, but the present invention is not limited to this configuration. For example, as the light receiving element, a photoelectric conversion element whose electric conductivity changes with light may be used. Alternatively, as the light receiving element, a photoelectric conversion element of a type that converts the characteristics of the received light (for example, the wavelength of light) into an electrical signal may be used. Alternatively, as the light receiving element, an element that converts the received light into information other than electrical information may be used.

In the present specification, "α includes A, B or C", "α contains any of A, B and C", and "α includes one selected from the group consisting of A, B and C". , Etc., unless otherwise specified, does not exclude the case where α includes a plurality of combinations of A to C. Furthermore, these expressions do not exclude cases where α contains other elements.

The following embodiments can be combined with each other as long as there is no technical contradiction.

<First Embodiment>
[Configuration of image sensor 10]
The outline of the image sensor 10 according to the first embodiment will be described with reference to FIGS. 1 to 7. FIG. 1 is a plan view showing individually the optical element and the light receiving element of the image sensor according to the embodiment of the present invention. As shown in FIG. 1, the image sensor 10 has an optical element 100 and a light receiving element 200. A plurality of optical elements 100 and a plurality of light receiving elements 200 are provided. The plurality of optical elements 100 and the light receiving elements 200 are arranged at the same intervals. In other words, the size of the optical element 100 and the size of the light receiving element 200 are substantially the same. In the example of FIG. 1, each of the plurality of optical elements 100 and the plurality of light receiving elements 200 are arranged in a matrix at the same pitch.

The optical element 100 has a first region 101, a second region 103, a third region 105, and a fourth region 107 having different optical characteristics from each other. The first region 101 is a region in which a polarizing filter is not provided. In the present embodiment, no optical filter is provided in the first region 101, and the light incident on the first region 101 is the optical element 100 except for the influence of reflection or absorption of the optical element 100. Is transparent. The second region 103 is a region provided with a first polarizing filter extending in the D1 direction. The third region 105 is a region provided with a second polarizing filter extending in the D2 direction.

The first polarizing filter and the second polarizing filter have different polarization characteristics. In this embodiment, the D2 direction is a direction orthogonal to the D1 direction. That is, the first polarizing filter and the second polarizing filter are polarizing filters having different polarization axes. It should be noted that the D1 direction and the D2 direction may be directions that intersect with each other, and may not be orthogonal to each other. In the present embodiment, the configuration in which each of the first polarizing filter and the second polarizing filter is a linearly polarized filter is illustrated, but other polarizing filters such as a circular polarizing filter may be used.

The fourth region 107 is a region provided with a light-shielding filter that blocks light. The first polarizing filter shields the polarized light in the D2 direction and transmits only the polarized light in the D1 direction. The second polarizing filter shields the polarized light in the D1 direction and transmits only the polarized light in the D2 direction. In other words, the optical element 100 has a plurality of filters (first polarizing filter, second polarizing filter, and light-shielding filter) having different optical characteristics from each other.

The light receiving element 200 has a light receiving unit 201 and a light emitting unit 203. The light receiving unit 201 is a region exposed from the light shielding unit 203. An electromotive force is generated by the intensity of the light incident on the light receiving unit 201. The light-shielding unit 203 is a region in which a light-shielding member is provided on the circuit constituting the light-receiving element 200, and prevents light incident on the light-shielding unit 203 from being reflected and incident on the light-receiving unit 201. Although the details will be described later, the light receiving element 200 includes a plurality of functional elements such as a transistor and a capacitive element, and wiring for connecting these functional elements. The light-shielding portion 203 suppresses reflection by the metal layer constituting the functional element and the wiring.

The sizes of the first region 101, the second region 103, the third region 105, and the fourth region 107 are substantially the same. The size of the light receiving unit 201 is smaller than that of each of the above four regions.

FIG. 2 is a plan view showing the optical element and the light receiving element of the image sensor according to the embodiment of the present invention in a stacked state. FIG. 2 is a diagram showing a positional relationship between the optical element 100 and the light receiving element 200 in one aspect when the image sensor 10 is used. Since the optical element 100 and the light receiving element 200 are arranged at the same pitch as described above, when the first region 101 of a certain optical element 100 overlaps the light receiving portion 201, the first region 101 of another optical element 100 Also overlaps the light receiving unit 201 corresponding to each. Since the size of the light receiving unit 201 is smaller than the size of the first region 101 as described above, the outer edge of the light receiving unit 201 is surrounded by the outer edge of the first region 101 in the state shown in FIG. The state of FIG. 2 is a state in which the light receiving unit 201 and the polarizing filter or the light blocking filter do not overlap, so that the filter is not applied. A state in which the light receiving unit 201 and the first region 101 overlap as shown in FIG. 2 may be referred to as a “first state”.

FIG. 3 is a cross-sectional view showing an outline of an image sensor according to an embodiment of the present invention. FIG. 3 is a diagram showing a positional relationship between the optical element 100 and the light receiving element 200 in one aspect when the image sensor 10 is used. As shown in FIG. 3, the image sensor 10 has a printed wiring board 110, a color filter 120, a microlens array 130, and a MEMS (Micro Electro Mechanical Systems) unit 300 in addition to the optical element 100 and the light receiving element 200. There is. The optical element 100 is provided on the light receiving element 200. The light receiving element 200 is provided on the printed wiring board 110. The light receiving element 200 and the printed wiring board 110 are connected by wire bonding 111. A color filter 120 and a microlens array 130 are provided on the light receiving element 200. A MEMS unit 300 is provided on the light receiving element 200.

The MEMS unit 300 includes a first movable unit 310, a second movable unit 320, a third movable unit 330 (see FIG. 4), and a cover member 390. The position of the cover member 390 in a plan view is fixed with respect to the light receiving element 200. As the cover member 390, for example, a frame member made of resin can be used. On the upper surface side of the cover member 390, the cover glass 391 is provided at a position overlapping the optical element 100, the color filter 120, and the microlens array 130 when viewed from above. The cover glass 391 is adhered above the cover member 390. Instead of the cover glass 391, a cover made of a material other than glass, such as resin or quartz, may be used. A first movable unit 310, a second movable unit 320, and a third movable unit 330 (see FIG. 4) are provided inside the cover member 390. The first movable unit 310 is fixed to the cover member 390. The second movable unit 320 is connected to the optical element 100 and moves together with the optical element 100 with respect to the first movable unit 310 and the cover member 390. The first movable unit 310 and the second movable unit 320 are configured by MEMS. Since a general MEMS can be used as a movable unit using MEMS, detailed description thereof will be omitted.

FIG. 4 is a plan view showing an outline of an image sensor according to an embodiment of the present invention. FIG. 4 is a diagram showing the positional relationship between the optical element 100 and the light receiving element 200 in one aspect when the image sensor 10 is used. As shown in FIG. 4, the third movable unit 330 is fixed to the optical element 100. The interaction between the first movable unit 310 and the second movable unit 320 causes the optical element 100, the second movable unit 320, and the third movable unit 330 to move in the D2 direction with respect to the cover member 390 (or the optical element 100). Move to. By the interaction between the second movable unit 320 and the third movable unit 330, the optical element 100 and the third movable unit 330 move in the D1 direction with respect to the cover member 390 (or the light receiving element 200). As described above, the optical element 100 is shifted in the D1 direction and the D2 direction with respect to the light receiving element 200 by the MEMS unit 300. Since the MEMS unit 300 controls the movement of the optical element 100, the MEMS unit 300 may be referred to as a control mechanism.

In this embodiment, a configuration in which the MEMS unit 300 is used as the control mechanism is illustrated, but the configuration is not limited to this configuration. The control mechanism may be any mechanism as long as it can movably control the position of the optical element 100 with respect to the light receiving element 200, and a configuration other than MEMS may be used.

FIG. 5 is a plan view showing a state in which the optical element of the image sensor according to the embodiment of the present invention is displaced in the first direction with respect to the light receiving element. By moving the optical element 100 in the D1 direction using the MEMS unit 300 shown in FIGS. 3 and 4, the light receiving unit 201 and the second region 103 (first polarizing filter) are overlapped with each other. In the present embodiment, the optical element 100 can be moved in the D1 direction by the interaction between the second movable unit 320 and the third movable unit 330 of FIG. In the state of FIG. 5, the light polarized in the D2 direction is shielded by the first polarizing filter, and only the light polarized in the D1 direction is incident on the light receiving unit 201. A state in which the light receiving unit 201 and the second region 103 overlap as shown in FIG. 5 may be referred to as a “second state”.

In an image sensor mounted on an in-vehicle camera of an automobile, for example, overexposure may occur due to light from the light of another automobile while driving at night. In such a case, since the light incident on the image sensor is incident in the lateral direction (D2 direction), the polarization component of the incident light is mainly the polarization component in the D2 direction. In such a case, overexposure can be suppressed by shielding the light polarized in the D2 direction by the first polarizing filter.

FIG. 6 is a plan view showing a state in which the optical element of the image sensor according to the embodiment of the present invention is displaced in the second direction with respect to the light receiving element. By moving the optical element 100 in the D2 direction using the MEMS unit 300 shown in FIGS. 3 and 4, the light receiving unit 201 and the third region 105 (second polarizing filter) are overlapped with each other. In the present embodiment, the optical element 100 can be moved in the D2 direction by the interaction between the first movable unit 310 and the second movable unit 320 in FIG. In the state of FIG. 6, the light polarized in the D1 direction is shielded by the second polarizing filter, and only the light polarized in the D2 direction is incident on the light receiving unit 201. A state in which the light receiving unit 201 and the third region 105 overlap as shown in FIG. 6 may be referred to as a “third state”.

In an image sensor mounted on an in-vehicle camera of an automobile, for example, when going out of a tunnel, whiteout may occur due to external light. In such a case, since the light incident on the image sensor is incident in the vertical direction (D1 direction), the polarization component of the incident light is mainly the polarization component in the D1 direction. In such a case, overexposure can be suppressed by shielding the light polarized in the D1 direction by the first polarizing filter.

FIG. 7 is a plan view showing a state in which the optical element of the image sensor according to the embodiment of the present invention is displaced in the first direction and the second direction with respect to the light receiving element. By moving the optical element 100 in the D1 direction and the D2 direction using the MEMS unit 300 shown in FIGS. 3 and 4, the light receiving unit 201 and the fourth region 107 (light shielding filter) are overlapped with each other. In the present embodiment, the optical element 100 can be moved in the D1 direction by the interaction between the second movable unit 320 and the third movable unit 330 in FIG. 4, and the first movable unit 310 and the second movable unit 320 can be moved. The optical element 100 can be moved in the D2 direction by interacting with. In the state of FIG. 7, since the light is shielded by the light blocking filter, the light does not enter the light receiving unit 201. A state in which the light receiving unit 201 and the fourth region 107 overlap as shown in FIG. 7 may be referred to as a “fourth state”.

The above shading filter is used for calibrating the black level of an image sensor and the like.

As described above, the MEMS unit 300 (control mechanism) shifts the optical element 100 and controls the first state, the second state, and the third state.

As described above, according to the image sensor 10 of the present embodiment, the position of the optical element 100 is controlled by the MEMS unit 300, and by superimposing a different filter on the light receiving unit 201, an imaging abnormality such as overexposure may occur depending on the situation. It can be suppressed.

<Second Embodiment>
The outline of the image sensor 10A according to the second embodiment will be described with reference to FIG. FIG. 8 is a plan view showing the light receiving element and the optical element of the image sensor according to the embodiment of the present invention individually. The image sensor 10A according to the second embodiment is similar to the image sensor 10 according to the first embodiment, but the configuration of the optical element 100A and the light receiving element 200A of the image sensor 10A is the optical element 100 and the light receiving element of the image sensor 10. It differs from the configuration of the element 200.

The optical element 100A includes a first region 101A, a second region 103A, a third region 105A, a fourth region 107A, a fifth region 141A, a sixth region 143A, a seventh region 145A, an eighth region 147A, and a ninth region 149A. Has. Since the first region 101A to the fourth region 107A are the same as the first region 101 to the fourth region 107 in FIG. 1, the description thereof will be omitted.

The fifth region 141A is a region provided with a first ND (Neutral Density) filter. The sixth region 143A is a region provided with the second ND filter. The seventh region 145A is a region provided with a third ND filter. The second ND filter is a filter having a higher concentration than the first ND filter. The third ND filter is a filter having a higher concentration than the second ND filter. That is, the second ND filter has a larger reduction in the amount of light than the first ND filter, and the third ND filter has a larger reduction in the amount of light than the second ND filter. As described above, the optical element 100A includes ND filters having different densities.

The eighth region 147A is a region provided with a third polarizing filter in the oblique direction extending from the upper right to the lower left. The ninth region 149A is a region provided with a fourth polarizing filter in the oblique direction extending from the upper left to the lower right. The polarization direction of the fourth polarizing filter is orthogonal to the polarization direction of the third polarizing filter.

As shown in FIG. 8, the light receiving portion 201A of the light receiving element 200A is provided at a position corresponding to the first region 101A. By providing each polarizing filter, each ND filter, and a light-shielding filter around the first region 101A in which the polarizing filter is not provided, the optical element 100A has a positive direction or a negative direction in each of the D1 direction and the D2 direction. Eight types of filters can be superimposed on the light receiving unit 201A simply by moving in the direction.

As described above, according to the image sensor 10A of the present embodiment, the same effect as that of the image sensor 10 of the first embodiment can be obtained. In addition, more types of filters can be used than the image sensor 10 of the first embodiment.

<Third Embodiment>
The outline of the image sensor 10B according to the third embodiment will be described with reference to FIG. FIG. 9 is a cross-sectional view showing an outline of an image sensor according to an embodiment of the present invention. The image sensor 10B according to the third embodiment is similar to the image sensor 10 according to the first embodiment, but the configuration of the optical element 100B and the MEMS unit 300B of the image sensor 10B is the optical element 100 and the MEMS of the image sensor 10. It differs from the configuration of the unit 300.

As shown in FIG. 9, the optical element 100B of the image sensor 10B includes a first optical element 150B and a second optical element 160B. The first optical element 150B and the second optical element 160B are arranged so as to be overlapped with each other in a plan view. The movement of each of the first optical element 150B and the second optical element 160B is controlled by the MEMS unit 300B. Although details will be described later, the first optical element 150B has a first filter having first optical characteristics. The second optical element 160B has a second filter having a second optical characteristic, which is a characteristic different from the first optical characteristic. Since other configurations are the same as those shown in FIG. 3, detailed description thereof will be omitted.

FIG. 10 is a plan view showing individually the light receiving element and the optical element of the image sensor according to the embodiment of the present invention. As shown in FIG. 10, the first optical element 150B has a first region 101B-1 and a second region 103B. The second optical element 160B has a first region 101B-2 and a third region 105B. Since the first region 101B-1, 101B-2, the second region 103B, and the third region 105B have the same functions as the first region 101, the second region 103, and the third region 105 in FIG. 1, respectively, The explanation is omitted.

As shown in FIG. 10, the light receiving portion 201B of the light receiving element 200B is provided at a position corresponding to the first region 101B-1 of the first optical element 150B and the first region 101B-2 of the second optical element 160B. .. The light receiving unit 201B occupies about half the area of the light receiving element 200B. The first region 101B-1 occupies about half of the region of the first optical element 150B. The first region 101B-2 occupies about half the region of the second optical element 160B.

Each of the first optical element 150B and the second optical element 160B is moved in the D2 direction by the MEMS unit 300. When only the first optical element 150B moves in the D2 direction, the light receiving unit 201B and the first polarizing filter in the second region 103B overlap. Therefore, the light polarized in the D2 direction is shielded by the first polarizing filter, and only the light polarized in the D1 direction is incident on the light receiving unit 201B. When only the second optical element 160B moves in the D2 direction, the light receiving unit 201B and the second polarizing filter in the third region 105B overlap. Therefore, the light polarized in the D1 direction is shielded by the second polarizing filter, and only the light polarized in the D2 direction is incident on the light receiving unit 201B. When both the first optical element 150B and the second optical element 160B move in the D2 direction, the light receiving unit 201B and both the first polarizing filter and the second polarizing filter overlap. Therefore, no light is incident on the light receiving unit 201B.

As described above, by arranging the two optical elements on top of each other and combining them, both the functions of the polarizing filter and the functions of the light-shielding filter can be realized. With such a configuration, the area of the light receiving unit 201B can be increased, so that the light receiving sensitivity can be improved.

In the present embodiment, the optical element 100B shows an example in which two optical elements are vertically stacked, but the present invention is not limited to this configuration. For example, the optical element 100B may have a configuration in which three or more optical elements are stacked one above the other. Further, in the present embodiment, the configuration in which the two optical elements (150B and 160B) constituting the optical element 100B are both provided with a polarizing filter is illustrated, but the configuration is not limited to this configuration. For example, as the above two optical elements or three or more optical elements, each of a polarizing filter, a light blocking filter, an ND filter, and a color filter may be used. For example, when the optical element 100B is composed of three optical elements, an ND filter is used in addition to the above-mentioned first optical element 150B (first polarizing filter) and second optical element 160B (second polarizing filter). May be good.

<Fourth Embodiment>
The overall configuration of the image sensor according to the first to third embodiments will be described with reference to FIG. The image sensors 10 to 10B according to the first to third embodiments described above correspond to each pixel circuit 400C of the image sensor 10C according to the following fourth embodiment.

[Circuit configuration of image sensor 10C]
FIG. 11 is a plan view showing an outline of an image sensor according to an embodiment of the present invention. As shown in FIG. 11, the image sensor 10C includes a pixel circuit 400C, a row selection scanning circuit 500C, a readout circuit 600C, and a signal processing circuit 700C. The image sensor 10C is divided into an imaging region 401C and a peripheral region 403C. The imaging area 401C is an area in which the pixel circuit 400C is arranged. The peripheral region 403C is a peripheral region around the imaging region 401C, and is an region in which the row selection scanning circuit 500C, the readout circuit 600C, and the signal processing circuit 700C are arranged. One pixel circuit 400C in FIG. 11 corresponds to one light receiving element 200 in FIG. In FIG. 11, the optical element 100 of FIG. 1 is omitted.

The pixel circuits 400C are arranged in a matrix in a rectangular imaging region 401C. The pixel circuits 400C are arranged in a matrix of N rows and M columns. In the example of FIG. 11, N = M = 10, but N and M are not limited to this value. The pixel circuit 400C has a photoelectric conversion element. The photoelectric conversion element generates electric power based on the captured image. The pixel circuit 400C generates a signal (for example, a gradation signal) corresponding to the generated electric power. The detailed circuit configuration of the pixel circuit 400C will be described later.

The row selection scanning circuit 500C is arranged at a position adjacent to the imaging region 401C in the row direction in the peripheral region 403C. A horizontal signal line 510C is connected to the row selection scanning circuit 500C. The horizontal signal line 510C extends in the row direction from the row selection scanning circuit 500C toward the imaging region 401C. The horizontal signal line 510C is connected to a plurality of pixel circuits 400C arranged in the same line. Although details will be described later, a control signal for controlling each pixel circuit 400C is input to the horizontal signal line 510C. The control signal is sequentially input for each horizontal signal line 510C of each line. For example, the control signal is sequentially input for each horizontal signal line 510C of each line, such as the first line, the second line, the third line, and so on. However, the control signal may not be input sequentially as described above, but may be input randomly.

The readout circuit 600C is arranged at a position adjacent to the imaging region 401C in the column direction in the peripheral region 403C. A vertical signal line 610C is connected to the readout circuit 600C. The vertical signal line 610C extends in the column direction from the readout circuit 600C toward the imaging region 401C. The vertical signal line 610C is connected to a plurality of pixel circuits 400C arranged in the same row. Although details will be described later, a signal is supplied to the vertical signal line 610C from the pixel circuit 400C arranged in the line selected by the line selection scanning circuit 500C. Specifically, a gradation signal (voltage) corresponding to the electric power generated by the photoelectric conversion element provided in each pixel circuit 400C is supplied to the vertical signal line 610C. The gradation signal supplied to the vertical signal line 610C is converted into a digital signal by the readout circuit 600C.

The readout circuit 600C includes a comparison circuit 620C, a counter circuit 630C, and a horizontal transfer scanning circuit 640C. The comparison circuit 620C and the counter circuit 630C are provided corresponding to each row. That is, M comparison circuits 620C and M counter circuits 630C are arranged in the row direction.

The comparison circuit 620C outputs an output signal based on the gradation signal received via the vertical signal line 610C connected to the input terminal and the lamp waveform 623C. The lamp waveform 623C is a waveform generated by the lamp waveform generation circuit 621C. As shown in FIG. 11, the lamp waveform 623C is a triangular waveform, and the inclined portion of the triangular waveform is inclined at a constant inclination angle. The comparison circuit 620C compares the triangular waveform with the gradation signal and switches the output signal when the voltages of both match (for example, the output signal is switched from the Low level to the High level).

The counter circuit 630C counts from the start of the triangular waveform to the switching of the output signal of the comparison circuit 620C based on the output signals from the clock waveform 633C and the comparison circuit 620C generated by the clock generation circuit 631C. As described above, the gradation signal is converted into a gradation digital signal by switching the output signal of the comparison circuit 620C and counting the counter circuit 630C. In other words, the read circuit 600C has an A / D conversion function.

The horizontal transfer scanning circuit 640C sequentially reads out the gradation digital signals counted by the counter circuit 630C for each column. When the horizontal transfer scanning circuit 640C reads out the gradation digital signal for one row, the gradation signal of the row selected by the row selection scanning circuit 500C can be read out as the gradation digital signal.

The signal processing circuit 700C is connected to the horizontal transfer scanning circuit 640C of the reading circuit 600C. Although the details will be described later, the signal processing circuit 700C has a determination unit having a first determination function, a second determination function, and a third determination function for images captured in different states. Further, the signal processing circuit 700C has a function of operating the optical element 100C to filter or switch based on the results of the first determination and the second determination. Further, the signal processing circuit 700C performs noise removal processing on the gradation digital signal corresponding to each pixel circuit 400C received from the horizontal transfer scanning circuit 640C. For example, the signal processing circuit 700C performs a process of removing a phenomenon in which the value of the gradation digital signal corresponding to the pixel circuit 400C of a specific row or column shows an abnormal value, that is, a so-called “horizontal streak” or “vertical streak”. In addition, the signal processing circuit 700C performs processing such as correction of defective pixels and reduction of random noise. The signal processing circuit 700C transmits the noise-removed signal to an external device.

In FIG. 11, a configuration in which the pixel circuit is arranged only in the imaging region 401C is illustrated, but the configuration is not limited to this configuration. For example, a dummy pixel circuit having the same or similar configuration as the pixel circuit 400C may be provided in the peripheral region 403C. In this case, the dummy pixel circuit may be connected to the horizontal signal line 510C or the vertical signal line 610C to which the pixel circuit 400C is connected at a position adjacent to the pixel circuit 400C. The photoelectric conversion element may be arranged in the dummy pixel circuit, and the node corresponding to the position where the photoelectric conversion element is arranged in the pixel circuit 400C may be in an open state. When the photoelectric conversion element is arranged in the dummy pixel circuit, the photoelectric conversion element may be shielded from light. The optical element 100C may be provided for the dummy pixel circuit.

In FIG. 11, a configuration in which the pixel circuits 400C are arranged in a matrix is illustrated, but the configuration is not limited to this configuration. For example, the pixel circuits 400C may be arranged in a shape having a periodicity different from the matrix shape shown in FIG. 11, or may be arranged irregularly. Further, in FIG. 11, a configuration in which the imaging region 401C is rectangular is illustrated, but the configuration is not limited to this configuration. For example, the imaging region 401C may be polygonal, circular (including a perfect circle and an ellipse), or curved.

[Circuit configuration of pixel circuit and output circuit]
The circuit configuration of the pixel circuit and the output circuit used in this embodiment will be described with reference to FIG. FIG. 12 is a circuit configuration diagram showing a pixel circuit of an image sensor according to an embodiment of the present invention. Although details will be shown below, the pixel circuit 900C shown in FIG. 12 has a circuit configuration common to the plurality of pixel circuits 400C of the present embodiment. In the following description, the region provided with the photoelectric conversion element 903C of FIG. 12 corresponds to the light receiving portion 201 of FIG. 1, and the region provided with the element other than the photoelectric conversion element 903C corresponds to the light shielding portion 203 of FIG. .. The output circuit 920C shown in FIG. 12 may be provided for each pixel circuit 400C, or may be provided for a plurality of pixel circuits 400C. The pixel circuit shown in FIG. 12 is an example, and the present invention is not limited to this pixel circuit.

The pixel circuit 900C includes a read transistor 901C, a photoelectric conversion element 903C, a transfer transistor 905C, a reset transistor 907C, a holding capacitance 909C, and a selection transistor 913C. A parasitic capacitance 911C is formed between the first terminal 901Ca of the readout transistor 901C and the first power supply line 410C. The second terminal 901Cb of the read transistor 901C is connected to the first power supply line 410C. The first terminal 903Ca of the photoelectric conversion element 903C is connected to the first terminal 901Ca via the transfer transistor 905C. The second terminal 903Cb of the photoelectric conversion element 903C is connected to the second power supply line 990C to which a voltage different from that of the first power supply line 410C is supplied. The reset transistor 907C is arranged between the first terminal 901Ca and the first power supply line 410C. The holding capacity 909C is arranged between the first terminal 901Ca and the second power supply line 990C. The selection transistor 913C is connected to the third terminal 901Cc of the readout transistor 901C. In other words, the selection transistor 913C is arranged between the read transistor 901C and the output terminal 950C.

The output circuit 920C includes a read transistor 901C, a selection transistor 913C, and a constant current circuit 921C. The readout transistor 901C and the selection transistor 913C are transistors common to the pixel circuit 900C and the output circuit 920C. The constant current circuit 921C is arranged between the second power supply line 990C and the output terminal 950C.

[Operation flow of image sensor 10C]
FIG. 13 is a diagram showing an operation flow in determining an imaging abnormality of an image sensor according to an embodiment of the present invention. As described above, the determination unit of the signal processing circuit 700C has a first determination function, a second determination function, and a third determination function for images captured in different states. As shown in FIG. 13, when the imaging is started, the first determination is first performed (step S701).

The first determination function is a function for determining whether or not the number of pixels showing white in the captured image exceeds the threshold value in the state shown in FIG. 2 (the state in which the polarizing filter does not overlap the light receiving unit 201). is there. When the signal processing circuit 700C determines that the number of pixels indicating white exceeds the threshold value by the first determination (in the case of “NG” in step S701), the optical element 100C is operated to cause the light receiving unit 201C to be 1 The second filter (for example, the first polarizing filter in the first region 103 as shown in FIG. 5) is set to overlap (step S703). On the other hand, when the signal processing circuit 700C determines that the number of pixels showing white does not exceed the threshold value by the first determination (in the case of "OK" in step S701), the signal processing circuit 700C terminates the determination function.

The second determination function is a function for determining whether or not the number of pixels showing white in the image captured in the state shown in FIG. 5 exceeds the threshold value. When the signal processing circuit 700C determines that the number of pixels indicating white exceeds the threshold value by the second determination (in the case of “NG” in step S705), the optical element 100C is operated to cause the light receiving unit 201C to have 2 The second filter (for example, the second polarizing filter in the second region 105 as shown in FIG. 6) is set to overlap (step S707). On the other hand, when the signal processing circuit 700C determines that the number of pixels showing white does not exceed the threshold value by the second determination (in the case of "OK" in step S705), the signal processing circuit 700C proceeds to the imaging abnormality determination in step S711.

The third determination function is a function for determining whether or not the number of pixels showing white in the image captured in the state shown in FIG. 6 exceeds the threshold value. The signal processing circuit 700C determines the imaging abnormality in step S711 based on the result of the determination (step S709) as to whether or not the number of pixels showing white exceeds the threshold value by the third determination.

In the above operation flow, when the determination of "OK" is made in the first determination of step S701, it is determined that the captured image does not have an imaging abnormality such as overexposure, and the determination function ends. On the other hand, when the determination of "NG" is made in the first determination of step S701, it means that overexposure due to external light from one direction has occurred or that a white object has been imaged. Is expected. When the number of pixels indicating white exceeds the threshold value due to overexposure as described above, the second determination with the above-mentioned first polarizing filter set, or the state with the second polarizing filter set. The judgment of "OK" is made by the third judgment of. On the other hand, when the number of pixels indicating white exceeds the threshold value by imaging a white object, the determination of "NG" is made in both the second determination and the third determination. That is, it is possible to determine the presence or absence of overexposure (imaging abnormality) in step S711 based on the second determination and the third determination.

The determination of the presence or absence of the above-mentioned imaging abnormality may be made for the entire frame or a part of a region of the frame.

Although the present invention has been described above with reference to the drawings, the present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit of the present invention. For example, a person skilled in the art who appropriately adds, deletes, or changes the design of a component based on the image sensor of each embodiment is also included in the scope of the present invention as long as it has the gist of the present invention. Further, the above-described embodiments can be appropriately combined as long as there is no contradiction with each other, and technical matters common to the respective embodiments are included in the respective embodiments even if there is no explicit description.

Further, in the above embodiment, the configuration in which the filter is arranged in each region provided in the optical element has been illustrated, but the configuration is not limited to this configuration. For example, a functional member other than the filter may be arranged in each region, such as a shutter using a liquid crystal. Further, in the above-described embodiment, a configuration in which a polarizing filter, a light-shielding filter, and an ND filter are used in each region of the optical element in each embodiment is illustrated, but a filter other than the above such as a color filter is used. It may be a configuration. Further, in the above embodiment, structures such as a grid member, a slit, and a microlens array may be provided below or above the optical element.

In addition, even if other effects different from the effects brought about by the above-described embodiments of the above-described embodiments, those that are clear from the description of the present specification or those that can be easily predicted by those skilled in the art are referred to. Naturally, it is understood that it is brought about by the present invention.

10: Image sensor, 100: Optical element, 101: 1st region, 103: 2nd region, 105: 3rd region, 107: 4th region, 110: Printed wiring board, 111: Wire bonding, 120: Color filter, 130: Microlens array, 141A: 5th region, 143A: 6th region, 145A: 7th region, 147A: 8th region, 149A: 9th region, 150B: 1st optical element, 160B: 2nd optical element, 200: Light receiving element, 201: Light receiving part, 203: Light shielding part, 300: MEMS unit, 310: First movable unit, 320: Second movable unit, 330: Third movable unit, 390: Cover member, 391: Cover glass , 400C: pixel circuit, 401C: imaging area, 403C: peripheral area, 410C: first power supply line, 500C: line selection scanning circuit, 510C: horizontal signal line, 600C: readout circuit, 610C: vertical signal line, 620C: comparison Circuit, 621C: Lamp waveform generation circuit, 623C: Lamp waveform, 630C: Counter circuit, 631C: Clock generation circuit, 633C: Clock waveform, 640C: Horizontal transfer scanning circuit, 700C: Signal processing circuit, 900C: Pixel circuit, 901C: Transistor, 901Ca: 1st terminal, 901Cb: 2nd terminal, 901Cc: 3rd terminal, 903C: Photoelectric conversion element, 903Ca: 1st terminal, 903Cb: 2nd terminal, 905C: Transfer transistor, 907C: Reset transistor, 909C: Retention capacity, 911C: Parasitic capacity, 913C: Selective transistor, 920C: Output circuit, 921C: Constant current circuit, 950C: Output terminal, 990C: Second power supply line

Claims (7)

A light receiving element having a light receiving part and
An optical element arranged on the light receiving portion and having a first region, a second region, and a third region adjacent to each other having different optical characteristics.
The optical element is shifted, the first state in which the light receiving portion and the first region overlap, the second state in which the light receiving portion and the second region overlap, and the second state in which the light receiving portion and the third region overlap. A control mechanism that controls three states and
Have,
A first filter is provided in the second region.
An image sensor in which a second filter different from the first filter is provided in the third region. The image sensor according to claim 1, wherein the first filter and the second filter are polarizing filters having different polarization characteristics. The image sensor according to claim 1 or 2, wherein the optical element further includes a fourth region provided with a light-shielding filter. The image sensor according to any one of claims 1 to 3, wherein the control mechanism includes MEMS. The image sensor according to any one of claims 1 to 4, wherein the optical element further has a fifth region and a sixth region provided with ND filters having different densities. The optical element includes a first optical element and a second optical element.
The first optical element and the second optical element are arranged so as to overlap each other in a plan view.
The first optical element has the first filter.
The image sensor according to any one of claims 1 to 5, wherein the second optical element has the second filter. It further has a determination unit that executes the first determination based on the number of pixels showing white in the captured image.
When the determination unit determines in the first determination that the number of pixels showing white exceeds the threshold value, the control mechanism superimposes a plurality of the first filters on the light receiving unit.
The determination unit executes the second determination based on the number of pixels showing white in the image captured with the first filter overlapping the light receiving unit.
When the determination unit determines in the second determination that the number of pixels showing white exceeds the threshold value, the control mechanism superimposes a plurality of the second filters on the light receiving unit.
The determination unit executes a third determination based on the number of pixels showing white in the image captured with the second filter overlapping the light receiving unit, and based on the second determination and the third determination. The image sensor according to any one of claims 1 to 5, which determines the presence or absence of an imaging abnormality.

Images