JP6549882B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging device capable of capturing an image of a subject and measuring the distance from a lens to the subject.

  In recent years, as a high-performance camera, a camera that can generate an arbitrary focus image and a stereoscopic image that can be focused after shooting has been researched and developed by acquiring not only conventional 2D images but also depth information. .

  As an optical technique for measuring the distance from the lens to the subject as one of methods for capturing such an image, a plurality of subject images (multi-focus image group) by mechanically shifting the in-focus position by the lens There is a method to shoot the In this method, it is known to measure the distance between a camera and a subject in an image to be captured by a so-called contrast-based multiple focusing method. In this case, it is necessary to provide a mechanism for shifting the in-focus position by the lens, and to perform a plurality of imaging operations.

  In addition, instead of mechanically shifting the in-focus position by the lens to obtain a plurality of subject images (multi-focus image group), a compound eye camera unit that images a plurality of single-eye images by shifting the in-focus position by a plurality of microlenses. An apparatus for obtaining a plurality of subject images (multi-focus image group) by the compound-eye camera unit and measuring the distance between the camera and the subject in the image to be captured by the multi-focus method based on contrast. For example, Patent Document 1 discloses the disclosure.

  Furthermore, as a conventional distance measuring device that measures the distance from a lens to a subject, light split by a plurality of prisms that separate incident light is imaged by a plurality of solid state imaging devices, and based on the focusing position and the focal distance of the lens An apparatus for measuring the distance to a subject is disclosed (see, for example, Patent Document 2).

  For example, as a conventional distance measuring apparatus, in the technique of mechanically shifting the in-focus position by the lens to obtain a plurality of object images (multi-focus image group), the focus drive is performed so that the in-focus position becomes a plurality. Although multiple focus images are to be acquired, this focus drive requires a certain amount of time, which is not suitable for imaging an object and measuring the distance to the subject.

  Further, in the technique of forming a compound eye camera unit in which a plurality of microlenses shift the in-focus position of a plurality of individual eye images to form an image, it is necessary to precisely arrange a plurality of microlenses having the same focal length. It is prone to problems and can be costly.

  In addition, in the technique of dispersing incident light with a prism (or a half mirror), there is a problem that the size of the camera is increased.

  As a method for solving these problems, among the incident light, the first image pickup element that absorbs light with a predetermined light absorption rate, photoelectrically converts it, and picks up the image of the subject, and photoelectrically converts the light transmitted through the first image pickup element A system is disclosed in which a subject image (multi-focus image group) is obtained by arranging a second imaging element for capturing an image of the subject on the optical axis of the lens at predetermined intervals (for example, Patent Reference 3).

  In this multi-focus camera, the difference in the amount of blur of the image of the subject imaged by the first imaging element and the second imaging element is the focal length, aperture ratio (F value), the distance from the subject to the lens, the first lens The distance from the subject to the lens is calculated using the dependence on the distance to the imaging element and the distance from the lens to the second imaging element. It has been proposed to employ an organic photoelectric conversion film in a photoelectric conversion unit as a first imaging element for absorbing light with a predetermined light absorption rate, performing photoelectric conversion, and capturing an image of a subject.

JP, 2009-216600, A Unexamined-Japanese-Patent No. 11-337313 gazette JP, 2013-205516, A

  By the way, in the prior art, when photographing a color image with the second imaging element, it is disposed on a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) sensor or thin film transistor circuit disposed as the second imaging element. The relationship between the color filter or the organic photoelectric conversion material having the Bayer arrangement and the organic photoelectric conversion material of the first imaging device is not considered.

  For this reason, depending on the absorption wavelength band of the first imaging device, the amount of light passing through the color filter of the second imaging device is significantly reduced, which causes a problem in distance measurement performance such as a decrease in sensitivity of the second imaging device. was there.

  Therefore, it is an object of the present invention to provide a high-sensitivity, high-performance multi-focus imaging apparatus.

  An imaging device according to an embodiment of the present invention reads a first photoelectric conversion unit that photoelectrically converts a first incident light of a predetermined ratio of incident light, and reads out a first imaging signal output from the first photoelectric conversion unit. A first imaging device having a first readout unit, and transmitting a second incident light other than the first incident light among incident light incident on the first photoelectric conversion unit, and corresponds to three primary colors of light A color filter having a first spectral sensitivity, a second spectral sensitivity, and a third spectral sensitivity, and a second photoelectric conversion for photoelectrically converting the second incident light transmitted through the color filter and the second incident light. Unit and a second image pickup device having a second read out unit for reading out a second image pickup signal output from the second photoelectric conversion unit, the second image pickup device in the incident direction of the incident light, Disposed at a position separated by a predetermined distance from the first imaging element A first wavelength representing the position of the first peak of the first spectral sensitivity, a second wavelength representing the position of the second peak of the second spectral sensitivity, and a position of the third peak of the third spectral sensitivity The third wavelength is distributed in this order from the short wavelength side to the long wavelength side, and the wavelength representing the position of the peak of the spectral sensitivity of the first photoelectric conversion unit that absorbs the first incident light is the first wavelength And longer than the second wavelength, or longer than the second wavelength and shorter than the third wavelength.

  It is possible to provide a high-sensitivity, high-performance multi-focus imaging device.

FIG. 2 is a diagram showing an imaging device 100. FIG. 2 is a view showing a cross-sectional structure of the imaging device 100. It is a figure which shows spectral sensitivity. It is a figure which shows the spectral sensitivity by the modification of embodiment.

  Hereinafter, an embodiment to which an imaging device of the present invention is applied will be described.

Embodiment
FIG. 1 is a diagram showing an imaging device 100. As shown in FIG.

  The imaging device 100 includes an imaging element 110 and an imaging element 120. The imaging element 110 includes a photoelectric conversion layer 111 and a signal readout unit 112. The photoelectric conversion layer 111 is formed on the signal readout unit 112. The imaging element 120 includes a color filter 121 and an imaging unit 122. The color filter 121 is formed on the imaging unit 122. In addition, although an electrode is formed on the photoelectric conversion layer 111, illustration is abbreviate | omitted in FIG.

  The imaging element 110 and the imaging element 120 are arranged at a predetermined distance apart by being held by a holder (not shown) or the like in the incident direction of light indicated by the arrow.

  The color filter 121 includes B (Blue), G (Green), and R (Red) filter sections 121B, 121G, and 121R arranged in a Bayer arrangement. The filter units 121 </ b> B, 121 </ b> G, and 121 </ b> R are arranged corresponding to the respective pixels of the imaging unit 122.

  The photoelectric conversion layer 111 has pixel regions arranged in a matrix in accordance with the filter portions 121B, 121G, and 121R. The pixel area of the photoelectric conversion layer 111 is shown in FIG. 1 similarly to the filter parts 121B, 121G, and 121R.

  FIG. 2 is a view showing a cross-sectional structure of the imaging device 100. As shown in FIG.

  The imaging device 110 has a signal readout circuit unit formed of a transparent thin film transistor (TFT) 60 in which a semiconductor island region 31 is formed of a single crystal silicon layer on a support substrate 20 made of glass.

  The TFT 60 (signal readout circuit portion) includes a semiconductor island region 31 and a source / drain region 32 formed inside the insulating film 22 formed on the support substrate 20 made of glass, a gate insulating film 21, a gate electrode 41, and signal readout. A wire 42 and an insulating film 23 are provided. The insulating films 22 and 23, the pixel electrode 43, and the counter electrode 44 may be formed of a material having high visible light transmittance.

  Among them, for example, a transparent conductive film such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide) or the like, or conductive made of thin Al, Mg, Au, Ag of several nm to several tens of nm is used for the counter electrode 44. A membrane may be used.

  A buried oxide film may be formed between the support substrate 20 made of glass and the insulating film 22. Also, instead of the TFT 60, a transparent MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) may be formed.

  Further, instead of the support substrate 20 made of glass, a substrate made of plastic with high light transmittance, quartz, sapphire or the like may be used.

  Also, instead of the TFT 60, a silicon-based material such as polycrystalline silicon or amorphous silicon, IGZO (In (indium), Ga (gallium), Zn (zinc), O (oxygen) -containing transparent oxide semiconductor) or ZnO A transparent transistor may be manufactured using an oxide semiconductor such as (zinc oxide) or an organic semiconductor such as pentacene.

  From the viewpoint of increasing the light transmittance of the signal readout circuit portion, it is desirable to use a thin silicon or oxide semiconductor with a thickness of several tens of nm, or an organic semiconductor material with high transmittance.

  The imaging element 110 is configured by forming the photoelectric conversion layer 111 and the counter electrode 44 on the pixel electrode 43 of the TFT 60 (signal readout circuit portion).

  The photoelectric conversion layer 111 is a photoelectric conversion layer made of an organic material, and is the photoelectric conversion layer 111 shown in FIG. The photoelectric conversion layer 111 is manufactured by laminating an organic photoconductive film on the pixel electrode 43.

  The support substrate 20 made of glass, the insulating film 22, the TFT 60, and the counter electrode 44 correspond to the signal readout unit 112 shown in FIG.

  In such an imaging element 110, when light is absorbed in the photoelectric conversion layer 111 in a state where a bias voltage is applied between the pixel electrode 43 and the counter electrode 44, charges are generated in the photoelectric conversion layer 111, and the pixel electrode 43 And is output as an imaging signal to the outside through the TFT 60.

  By forming an array of light detection elements in which the photoelectric conversion layer 111 and the signal readout unit 112 are combined, it is possible to detect an imaging signal with high accuracy and high speed.

  As the imaging device 120, a complementary metal oxide semiconductor (CMOS) imaging device configured with a photodiode 131 having a thickness of about 5 μm and a signal readout circuit unit 132 made of single crystal silicon is adopted.

  The imaging element 120 includes a silicon substrate 130, a photodiode 131, a signal readout circuit portion 132, an insulating film 133, and a color filter 121. The silicon substrate 130, the photodiode 131, the signal readout circuit portion 132, and the insulating film 133 correspond to the imaging portion 122 shown in FIG. As described above, the photodiode 131 and the signal readout circuit unit 132 are configured by CMOS.

  Here, the photoelectric conversion layer 111 used for the imaging device 110 mainly absorbs light of about 500 to 600 nm and performs photoelectric conversion, and transmits light in other bands.

  Further, a single crystal silicon photodiode having a thickness of about 5 μm used for the imaging device 120 absorbs light transmitted through the photoelectric conversion layer 111 and performs photoelectric conversion.

  The imaging device 100 photoelectrically converts light in a visible range of wavelengths of about 500 to about 600 nm by the imaging device 110, and photoelectrically converts light transmitted through the imaging device 110 by the imaging device 120.

  FIG. 3 is a diagram showing the spectral sensitivity, and FIG. 3 (A) shows the spectral sensitivity of the filter sections 121B, 121G, 121R in which the color filter 121 is Bayer-arranged, and FIG. 3 (B) is a diagram of FIG. It is the figure which added the spectral sensitivity of the photoelectric converting layer 111 to (A).

  In FIG. 3A, the spectral sensitivities of the filter sections 121B, 121G, and 121R are indicated by B, G, and R, respectively. The photodiode 131 of the imaging unit 122 can photoelectrically convert light of the entire band illustrated in FIG. For this reason, the imaging device 120 has three spectral sensitivities shown in FIG. These three spectral sensitivities correspond to the three primary colors of light.

  As shown in FIG. 3B, the photoelectric conversion layer 111 has a spectral sensitivity 111A in a band of about 500 to about 600 nm. The spectral sensitivity 111A is located between the spectral sensitivity G and the spectral sensitivity R, and the wavelength giving the intersection of the spectral sensitivity G and the spectral sensitivity R is equal to the wavelength of the absorption peak. Further, the absorption amounts of the spectral sensitivity G and the spectral sensitivity R at the intersection of the spectral sensitivity G and the spectral sensitivity R are equal to the absorption amounts at the absorption peak of the spectral sensitivity 111A.

  Thus, as the photoelectric conversion layer 111 having the spectral sensitivity 111A located between the spectral sensitivity G and the spectral sensitivity R, for example, there is an organic photoelectric conversion film such as anthraquinone or an azobenzene-based dye.

  The spectral sensitivity 111A of the photoelectric conversion layer 111 may be located on the longer wavelength side than the absorption peak (about 530 nm) of the spectral sensitivity G and on the shorter wavelength side than the absorption peak (about 600 nm) of the spectral sensitivity R . If the absorption peaks overlap, the sensitivity of the imaging device 120 may be too low.

  In other words, the wavelength representing the peak position of the spectral sensitivity 111A of the photoelectric conversion layer 111 is longer than the wavelength representing the peak position of the spectral sensitivity G and shorter than the wavelength representing the peak position of the spectral sensitivity R Just do it.

  Here, although the case where the wavelength of the absorption peak of the spectral sensitivity 111A is equal to the wavelength giving the intersection of the spectral sensitivity G and the spectral sensitivity R is described, the wavelength of the absorption peak of the spectral sensitivity 111A is the spectral sensitivity G and the spectrum If it is located between the sensitivities R, it does not have to coincide with the wavelength giving the intersection of the spectral sensitivity G and the spectral sensitivity R.

  Further, the case where the absorption amounts of the spectral sensitivity G and the spectral sensitivity R at the intersection of the spectral sensitivity G and the spectral sensitivity R are equal to the absorption amounts at the absorption peak of the spectral sensitivity 111A will be described. The amount may be larger or smaller than the absorption amount of the spectral sensitivity G and the spectral sensitivity R at the intersection point. The balance between the absorption at the absorption peak of the spectral sensitivity 111A and the absorption between the spectral sensitivity G and the spectral sensitivity R at the intersection affects the sensitivity of the imaging elements 110 and 120, so the balance of the sensitivities of the imaging elements 110 and 120 The balance should be set appropriately in consideration of

  The sensitivity of the imaging device 120 is high by using an organic photoelectric conversion material in which the principal wavelength of absorption is located in a portion where the spectral sensitivity G and the spectral sensitivity R of the imaging device 120 overlap as the photoelectric conversion layer 111 of the imaging device 110. Since the light of the wavelength is transmitted without being absorbed by the imaging element 110, the loss of light when viewed in the entire system of the imaging device 100 is reduced.

  In the imaging device 100 having the configuration as described above, a difference occurs in the amount of blur of the image of the subject imaged by the imaging element 110 and the imaging element 120. This is because the distances to the subject are different between the imaging element 110 and the imaging element 120.

  The difference in the amount of blur of the image of the subject is the focal length, aperture ratio (F value), the distance from the subject to the lens disposed on the incident side of the imaging device 110, the distance from the lens to the imaging device 110, and imaging from the lens Using the dependence on the distance to the element 120, the distance from the subject to the lens can be determined by calculation.

  Therefore, the imaging device 100 can be used as a multi-focus camera capable of acquiring an image including distance information.

  As described above, according to the embodiment, it is possible to provide the imaging apparatus 100 with high sensitivity and high performance and multiple focus.

  In addition, although the photoelectric conversion layer 111 demonstrated the form which has the spectral sensitivity 111A located between the spectral sensitivity G and the spectral sensitivity R above, the spectral sensitivity located between the spectral sensitivity B and the spectral sensitivity G May be included.

  FIG. 4 is a diagram showing spectral sensitivity according to a modification of the embodiment.

  As shown in FIG. 4, the photoelectric conversion layer 111 may have a spectral sensitivity 111 </ b> B in a band of about 430 to about 520 nm in addition to the spectral sensitivity 111 </ b> A in a band of about 500 to about 600 nm. The spectral sensitivity 111B is located between the spectral sensitivity B and the spectral sensitivity G, and the wavelength giving the intersection of the spectral sensitivity B and the spectral sensitivity G is equal to the wavelength of the absorption peak. Further, the absorption amounts of the spectral sensitivity B and the spectral sensitivity G at the intersection of the spectral sensitivity B and the spectral sensitivity G are equal to the absorption amount at the absorption peak of the spectral sensitivity 111B.

  Thus, as a material of the photoelectric conversion layer having the spectral sensitivity 111 B located between the spectral sensitivity B and the spectral sensitivity G, for example, dioxazine dioxazine, quinacridone, perylene, indigoid, anthraquinone, xanthene dye, etc. There is an organic photoelectric conversion film.

  In order for the photoelectric conversion layer 111 to have two spectral sensitivities 111A and 111B, an anthraquinone which realizes the spectral sensitivity 111A, or an organic photoelectric conversion film of an azobenzene dye and a dioxazine dien which realizes the spectral sensitivity 111B. An organic photoelectric conversion film such as oxazine, quinacridone, perylene, indigoid, anthraquinone, or xanthene dye may be stacked to form the photoelectric conversion layer 111 having a two-layer structure.

  Further, instead of forming them in layers, the photoelectric conversion layer 111 may be formed of a material in which an organic photoelectric conversion film material for realizing the spectral sensitivity 111A and an organic photoelectric conversion film material for realizing the spectral sensitivity 111B are mixed.

  The spectral sensitivity 111B of the photoelectric conversion layer 111 may be located on the longer wavelength side than the absorption peak (about 430 nm) of the spectral sensitivity B and on the shorter wavelength side than the absorption peak (about 530 nm) of the spectral sensitivity G. . If the absorption peaks overlap, the sensitivity of the imaging device 120 may be too low.

  In other words, the wavelength representing the position of the peak of the spectral sensitivity 111B of the photoelectric conversion layer 111 is longer than the wavelength representing the position of the peak of spectral sensitivity B and shorter than the wavelength representing the position of the peak of spectral sensitivity G Just do it.

  In addition, although the case where the wavelength of the absorption peak of the spectral sensitivity 111B is equal to the wavelength giving the intersection of the spectral sensitivity B and the spectral sensitivity G is described here, the wavelength of the absorption peak of the spectral sensitivity 111B is the spectral sensitivity B and the spectral If it is located between the sensitivities G, it does not have to coincide with the wavelength giving the intersection of the spectral sensitivities B and the spectral sensitivities G.

  Further, the case where the absorption amounts of the spectral sensitivity B and the spectral sensitivity G at the intersection of the spectral sensitivity B and the spectral sensitivity G and the absorption amount at the absorption peak of the spectral sensitivity 111B are equal will be described. The amount may be larger or smaller than the absorption amount of the spectral sensitivity B and the spectral sensitivity G at the intersection point. The balance between the absorption at the absorption peak of the spectral sensitivity 111 B and the absorption between the spectral sensitivity B and the spectral sensitivity G at the intersection affects the sensitivity of the imaging elements 110 and 120, so the balance of the sensitivities of the imaging elements 110 and 120 The balance should be set appropriately in consideration of

  As described above, when the imaging device 110 of the imaging apparatus 100 has two spectral sensitivities 111A and 111B, the sensitivity of the imaging device 110 is further increased than in the case of the spectral sensitivity 111A alone, so that higher sensitivity and high performance are achieved. It is possible to provide a multi-focus imaging device 100.

  Although the imaging apparatus of the exemplary embodiment of the present invention has been described above, the present invention is not limited to the specifically disclosed embodiment, and does not deviate from the scope of the claims. Various modifications and variations are possible.

Reference Signs List 100 imaging device 110 imaging device 120 imaging device 111 photoelectric conversion layer 111A, 111B spectral sensitivity 112 signal readout unit 20 glass support substrate 21 gate insulating film 22 insulating film 23 insulating film 31 semiconductor island region 32 source / drain region 41 gate electrode 42 Signal readout line 43 pixel electrode 44 counter electrode 60 TFT
121B, 121G, 121R filter section 131 photodiode 132 signal readout circuit section 133 insulating film

Claims (5)

A first photoelectric conversion unit that photoelectrically converts a first incident light of a predetermined ratio in incident light; and a first reading unit that reads a first imaging signal output from the first photoelectric conversion unit; A first imaging element that transmits second incident light other than the first incident light among incident light incident on the first photoelectric conversion unit;
A color filter having a first spectral sensitivity, a second spectral sensitivity, and a third spectral sensitivity corresponding to three primary colors of light and transmitting the second incident light; and photoelectrically detecting the second incident light transmitted through the color filter A second imaging device having a second photoelectric conversion unit to convert and a second reading unit that reads a second imaging signal output from the second photoelectric conversion unit;
The second imaging device is disposed at a position separated by a predetermined distance from the first imaging device in the incident direction of the incident light.
A first wavelength representing the position of the first peak of the first spectral sensitivity, a second wavelength representing the position of the second peak of the second spectral sensitivity, and a third representing the position of the third peak of the third spectral sensitivity The wavelengths are distributed in this order from the short wavelength side to the long wavelength side,
The wavelength representing the position of the peak of the spectral sensitivity of the first photoelectric conversion portion absorbing the first incident light is longer than the first wavelength and shorter than the second wavelength, or the second wavelength An imaging device, which is longer than the third wavelength.   The wavelength representing the position of the peak of the spectral sensitivity of the first photoelectric conversion unit is the wavelength of the intersection of the first spectral sensitivity and the second spectral sensitivity, or the intersection of the second spectral sensitivity and the third spectral sensitivity. The imaging device according to claim 1 corresponding to a wavelength.   The imaging device according to claim 1, wherein the first photoelectric conversion unit is a first photoelectric conversion unit made of an organic material having the spectral sensitivity.   The first photoelectric conversion unit has a spectral sensitivity having a peak at a wavelength longer than the first wavelength and shorter than the second wavelength, and longer than the second wavelength and longer than the third wavelength. The imaging device according to any one of claims 1 to 3, having two spectral sensitivities of a spectral sensitivity having a peak at a short wavelength. The first photoelectric conversion unit is
A first photoelectric conversion portion made of a first organic material having a spectral sensitivity having a peak at a wavelength longer than the first wavelength and shorter than the second wavelength;
A first photoelectric conversion unit obtained by superposing the first photoelectric conversion unit made of a second organic material having a spectral sensitivity having a peak at a wavelength longer than the second wavelength and shorter than the third wavelength.
Or
Made of a first organic material having a spectral sensitivity having a peak at a wavelength longer than the first wavelength and shorter than the second wavelength, and longer than the second wavelength and shorter than the third wavelength The imaging device according to claim 4, which is a first photoelectric conversion unit produced by mixing a second organic material product having spectral sensitivity having a peak at a wavelength.

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