Patent Description:
In recent years, an imaging apparatus that performs phase difference detection by phase difference detection pixels in each of which part of a photoelectric conversion section is shielded from light, the phase difference detection pixels being provided in an image sensor, has been known (e.g., see Patent Literature <NUM>).

<CIT> discloses a solid-state imaging device with first pixels and second pixels. The first pixel has a first PD and a first photoelectric conversion film. The second pixel has a second PD and a second photoelectric conversion film. The first PD and the second PD are formed in a surface layer of a semiconductor substrate. The first photoelectric conversion film is formed over the first PD, in a position shifted in a rightward direction relative to the center of the first PD. The second photoelectric conversion film is formed over the second PD, in a position shifted in a leftward direction relative to the center of the second PD. The first photoelectric conversion film photoelectrically converts incident light incident on a right area of the first PD. The second photoelectric conversion film photoelectrically converts incident light incident on a left area of the second PD.

<CIT> discloses pixels that include: n-type charge storage layers for imaging which mainly photoelectrically convert a prescribed wavelength component in the visible region of the incident light, and store an electric charge as the signal for imaging; and n-type charge storage layers for focus detection which mainly photoelectrically convert a wavelength component in the IR region of the incident light, and store the electric charge as a signal for the focus detection. Parts of the respective charge storage layers for the focus detection are arranged in a p-type silicon substrate so as to be superimposed on the charge storage layer for imaging when viewed from the incident direction of the incident light.

<CIT> discloses an imaging device with a plurality of pixels each of which includes a microlens, first and second photoelectric conversion portions. The first photoelectric conversion portion is between the microlens and a focal point of the microlens. The second photoelectric conversion portion is at a position that is different from that of the focal point on a plane which is parallel to an imaging plane and which contains the focal point, and has a photoelectric conversion region deviated from an optical axis of the microlens in a direction of the imaging plane. The plurality of pixels includes a first pixel group and a second pixel group. The photoelectric conversion region is deviated from the optical axis in the direction in the first pixel group. The photoelectric conversion region is deviated from the optical axis in the direction to be opposite to the first pixel group in the second pixel group.

In the phase difference detection pixel, however, since part (e.g., half) of the photoelectric conversion section is shielded from light, the sensitivity is lower than that of a normal imaging pixel; therefore, sufficient signal-noise ratio (SNR) cannot be obtained under low illuminance and phase difference detection might not be performed accurately. As a result, the obtained images might be out of focus.

In addition, in the normal imaging pixel, color mixing from the adjacent pixel might adversely affect color reproducibility and SNR.

The present technology, which has been made in view of such circumstances, enables higher-quality images to be obtained.

According to a first aspect, the present invention provides an image sensor in accordance with independent claim <NUM>. Further aspects are set forth in the dependent claims, the drawings and the following description.

Imaging pixels for generating an image can be further included. The phase difference detection pixels can be arranged to be distributed among the plurality of imaging pixels arranged two-dimensionally in a matrix form.

A difference in output between the photoelectric conversion layer in the phase difference detection pixel and the imaging pixel placed around the phase difference detection pixel can be used for the phase difference detection.

The phase difference detection pixel can further include, below the organic photoelectric conversion film, a light-shielding film that partially shields the photoelectric conversion section from light. The organic photoelectric conversion film can photoelectrically convert light partially blocked out by the light-shielding film.

The phase difference detection pixel can include, as the plurality of photoelectric conversion layers, at least two layers of photoelectric conversion sections formed in a substrate, each photoelectric conversion section being split.

The phase difference detection pixel can include, as the plurality of photoelectric conversion layers, at least two layers of organic photoelectric conversion films, each organic photoelectric conversion film being split or partially shielded from light.

The pixels can be imaging pixels for generating an image.

The imaging pixel can include an organic photoelectric conversion film partially formed as the top photoelectric conversion layer among the plurality of photoelectric conversion layers, and a photoelectric conversion section partially shielded from light at a boundary part with another adjacent imaging pixel, as the photoelectric conversion layer formed in a substrate below the organic photoelectric conversion film. The organic photoelectric conversion film can be formed at the boundary part with the other imaging pixel.

The phase difference detection pixel can include, as the plurality of photoelectric conversion layers, an organic photoelectric conversion film and a photoelectric conversion section that is formed in a substrate. The organic photoelectric conversion film and the photoelectric conversion section can be controlled with different frame rates.

According to an aspect of the present technology, there is provided an electronic apparatus according to claim <NUM>.

According to an aspect of the present technology, higher-quality images can be obtained.

<FIG>, <FIG>, <FIG> and <FIG> form embodiments of the claimed invention. <FIG>, <FIG>, <FIG>, <FIG> and <FIG> form examples being useful to understand the claimed invention. <FIG>, <FIG>, <FIG> and <FIG> form examples not forming part of the claimed invention.

Hereinafter, embodiments of the present technology will be described with reference to the drawings. The description is given in the following order.

<FIG> illustrates an example configuration of an imaging apparatus of a first embodiment of the present technology. An imaging apparatus <NUM> illustrated in <FIG> is an apparatus that captures an image of an object by performing auto focus (AF) using a phase difference detection method (phase difference AF), and outputs the image of the object as an electrical signal.

The imaging apparatus <NUM> illustrated in <FIG> includes a lens <NUM>, an optical filter <NUM>, an image sensor <NUM>, an A/D conversion section <NUM>, a clamp section <NUM>, a phase difference detection section <NUM>, a lens control section <NUM>, a defect correction section <NUM>, a demosaic section <NUM>, a linear matrix (LM)/white balance (WB)/gamma correction section <NUM>, a luminance chroma signal generation section <NUM>, and an interface (I/F) section <NUM>.

The lens <NUM> adjusts a focal length of object light that is to enter the image sensor <NUM>. A diaphragm (not shown) that adjusts the amount of the object light that is to enter the image sensor <NUM> is provided downstream from the lens <NUM>. The lens <NUM> can have any specific configuration; for example, the lens <NUM> may be configured with a plurality of lenses.

The object light that has been transmitted through the lens <NUM> enters the image sensor <NUM> via the optical filter <NUM> configured as, for example, an IR-cut filter that transmits light excluding infrared light.

The image sensor <NUM> is provided with a plurality of pixels including photoelectric conversion devices, such as photodiodes, which photoelectrically convert the object light. Each pixel converts the object light to an electrical signal. The image sensor <NUM> may be, for example, a CCD image sensor that performs transfer using a circuit device called charge coupled device (CCD) in order to read charge generated from light by the photoelectric conversion devices, or a CMOS image sensor that uses a complementary metal oxide semiconductor (CMOS) and has an amplifier for each unit cell.

The image sensor <NUM> has color filters for the respective pixels on the object side of the photoelectric conversion devices. As the color filters, filters of colors such as red (R), green (G), and blue (B) are arranged in the Bayer array, for example, above the respective photoelectric conversion devices. That is, the image sensor <NUM> photoelectrically converts the object light of each color transmitted through the filter, and supplies the resulting electrical signal to the A/D conversion section <NUM>.

The color filters of the image sensor <NUM> can have any color; a color other than RGB may be included, or some or all colors of RGB may be excluded from use. In addition, the colors can be arranged in any array; an array other than the Bayer array may be adopted. For example, as the array of the color filters of the image sensor <NUM>, an array including a white pixel (disclosed in <CIT>) or an emerald pixel, or a clear bit array can be applied.

In the image sensor <NUM>, pixels (imaging pixels) that generate signals for generating an image based on the received object light and pixels (phase difference detection pixels) that generate signals for performing AF by phase difference detection are arranged.

<FIG> illustrates an example of the pixel arrangement of the image sensor <NUM>.

As illustrated in <FIG>, a plurality of imaging pixels indicated by white squares are arranged two-dimensionally in a matrix form in the image sensor <NUM>. The imaging pixels include R pixels, G pixels, and B pixels, which are arranged regularly in accordance with the Bayer array.

Furthermore, in the image sensor <NUM>, a plurality of phase difference detection pixels indicated by black squares are arranged to be distributed among the plurality of imaging pixels arranged two-dimensionally in a matrix form. The phase difference detection pixels replace part of predetermined imaging pixels in the image sensor <NUM> to be arranged regularly in a specific pattern. In the example of <FIG>, two G pixels are replaced with phase difference detection pixels P1 and P2. Note that the phase difference detection pixels may be arranged irregularly in the image sensor <NUM>. Regular arrangement of the phase difference detection pixels facilitates signal processing such as defect correction which is described later, and irregular arrangement of the phase difference detection pixels causes artifacts due to defect correction to be irregular, making the artifacts less visible (less likely to be recognized).

Returning to the description of <FIG>, the A/D conversion section <NUM> converts electrical signals (analog signals) of RGB supplied from the image sensor <NUM> to digital data (image data). The A/D conversion section <NUM> supplies the image data (RAW data) as digital data to the clamp section <NUM>.

The clamp section <NUM> subtracts a black level, which is a level determined as black, from the image data. The clamp section <NUM> supplies the image data output from the phase difference detection pixels, among the image data from which the black level has been subtracted, to the phase difference detection section <NUM>. In addition, the clamp section <NUM> supplies the image data from which the black level has been subtracted for all the pixels to the defect correction section <NUM>.

In other words, while only the output of the phase difference detection pixels is used for phase difference detection, the output of the phase difference detection pixels as well as the output of the imaging pixels is used for generation of images.

The phase difference detection section <NUM> performs phase difference detection processing based on the image data from the clamp section <NUM> to determine whether or not focusing is obtained with respect to an object targeted for focusing (focusing target). When an object in a focus area is focused, the phase difference detection section <NUM> supplies, as a focusing determination result, information indicating that focusing is obtained to the lens control section <NUM>. When the focusing target is not focused, the phase difference detection section <NUM> calculates the amount of focus deviation (defocus amount) and supplies, as a focusing determination result, information indicating the calculated defocus amount to the lens control section <NUM>.

The lens control section <NUM> controls the driving of the lens <NUM>. Specifically, the lens control section <NUM> calculates the driving amount of the lens <NUM> based on the focusing determination result supplied from the phase difference detection section <NUM>, and moves the lens <NUM> in accordance with the calculated driving amount.

For example, when focusing is obtained, the lens control section <NUM> keeps the lens <NUM> at the current position. When focusing is not obtained, the lens control section <NUM> calculates the driving amount based on the focusing determination result indicating the defocus amount and the position of the lens <NUM>, and moves the lens <NUM> in accordance with the driving amount.

In addition to the above-described phase difference AF, the lens control section <NUM> may perform contrast AF to control the driving of the lens <NUM>. For example, when information indicating the amount of focus deviation (defocus amount) is supplied as the focusing determination result from the phase difference detection section <NUM>, the lens control section <NUM> may determine the direction of focus deviation (front focus or rear focus) and perform contrast AF with respect to the direction.

Based on the image data from the clamp section <NUM>, the defect correction section <NUM> performs correction of pixel values, i.e., defect correction, on defective pixels where correct pixel values cannot be obtained. The defect correction section <NUM> supplies the image data subjected to the correction of defective pixels to the demosaic section <NUM>.

The demosaic section <NUM> performs demosaic processing on the RAW data from the defect correction section <NUM>, performing complementation of color information or the like, to convert the RAW data to RGB data. The demosaic section <NUM> supplies the image data (RGB data) after the demosaic processing to the LM/WB/gamma correction section <NUM>.

The LM/WB/gamma correction section <NUM> performs correction of color property on the RGB data from the demosaic section <NUM>. Specifically, the LM/WB/gamma correction section <NUM> performs processing of correcting, in order to fill the gap between chromaticity points of primary colors (RGB) defined by the standard and chromaticity points of an actual camera, color signals of the image data using a matrix coefficient to change color reproducibility. In addition, the LM/WB/gamma correction section <NUM> sets a gain for white with respect to the value of each channel of the RGB data to adjust white balance. Furthermore, the LM/WB/gamma correction section <NUM> performs gamma correction for adjusting the relative relationship between colors of the image data and output device property so as to obtain display closer to the original. The LM/WB/gamma correction section <NUM> supplies the image data (RGB data) after the correction to the luminance chroma signal generation section <NUM>.

The luminance chroma signal generation section <NUM> generates a luminance signal (Y) and chroma signals (Cr and Cb) from the RGB data supplied from the LM/WB/gamma correction section <NUM>. Upon generating the luminance chroma signals (Y, Cr, and Cb), the luminance chroma signal generation section <NUM> supplies the luminance signal and chroma signals to the I/F section <NUM>.

The I/F section <NUM> outputs the supplied image data (luminance chroma signals) to the outside of the imaging apparatus <NUM> (e.g., a storage device that stores the image data or a display device that displays images based on the image data).

<FIG> is a cross-sectional view illustrating an example structure of phase difference detection pixels of the present technology. The phase difference detection pixels P1 and P2 are arranged adjacent to each other in <FIG>, but may be arranged with a predetermined number of imaging pixels placed therebetween as illustrated in <FIG>.

As illustrated in <FIG>, a photodiode <NUM> as a photoelectric conversion section is formed in a semiconductor substrate (Si substrate) <NUM> in each of the phase difference detection pixels P1 and P2. Above the semiconductor substrate <NUM>, a light-shielding film <NUM> and a color filter <NUM> are formed in the same layer, and above them, specifically, right above the light-shielding film <NUM>, an organic photoelectric conversion film <NUM> having substantially the same area as the light-shielding film <NUM> is formed. In addition, an on-chip lens <NUM> is formed above the organic photoelectric conversion film <NUM>.

The light-shielding film <NUM> may be made of metal, or may be a black filter that absorbs light. Alternatively, the light-shielding film <NUM> may be configured with an electrode of the organic photoelectric conversion film <NUM>. In that case, a wiring layer can be omitted, which results in lower height of the image sensor <NUM>, contributing to improved sensitivity of the photodiode <NUM>.

The color of the color filter <NUM> may be the same or different between the phase difference detection pixel P1 and the phase difference detection pixel P2. In the case where the phase difference detection pixels P1 and P2 are white pixels, it is possible not to provide the color filter <NUM>.

The organic photoelectric conversion film <NUM> photoelectrically converts light with a specific wavelength. For example, the organic photoelectric conversion film <NUM> photoelectrically converts light of one of the three colors, red, green, and blue.

As an organic photoelectric conversion film that photoelectrically converts green light, for example, an organic photoelectric conversion material including a rhodamine-based dye, a meracyanine-based dye, quinacridone, or the like can be used. As an organic photoelectric conversion film that photoelectrically converts red light, an organic photoelectric conversion material including a phthalocyanine-based dye can be used. As an organic photoelectric conversion film that photoelectrically converts blue light, an organic photoelectric conversion material including a coumarin-based dye, tris-(<NUM>-hydrixyquinoline)aluminum (Alq3), a meracyanine-based dye, or the like can be used.

The organic photoelectric conversion film <NUM> may also photoelectrically convert light other than visible light (e.g., red light, green light, and blue light), such as white light, infrared light, or ultraviolet light.

Each phase difference detection pixel illustrated in <FIG> is provided with one on-chip lens <NUM> and a plurality of photoelectric conversion layers formed below the on-chip lens <NUM>, specifically, the organic photoelectric conversion film <NUM> and the photodiode <NUM> from the top. Here, when the surface where the on-chip lens <NUM> is formed is defined as a light-receiving surface of each pixel, the organic photoelectric conversion film <NUM> is formed partly with respect to the light-receiving surface (hereinafter described as being partially formed). In addition, part (e.g., half) of the photodiode <NUM> is shielded from light by the light-shielding film <NUM> (hereinafter, the photodiode <NUM> is described as being partially shielded from light).

In <FIG>, the phase difference detection pixels P1 and P2 are shielded from light on the left side and the right side, respectively; however, depending on the pixel arrangement, the phase difference detection pixels may be shielded from light on the upper side and the lower side, or may be obliquely shielded from light.

Next, referring to <FIG>, a conventional phase difference detection pixel and a phase difference detection pixel of the present technology are compared in structure.

The conventional phase difference detection pixel illustrated on the left side in <FIG> differs from the phase difference detection pixel of the present technology illustrated on the right side in <FIG> in that the organic photoelectric conversion film <NUM> is not provided.

With the structure of the conventional phase difference detection pixel, part of incident light L1 is reflected by the light-shielding film <NUM> of the pixel on the left side and then diffusely reflected within the image sensor <NUM>, and part of incident light R1 is reflected by the light-shielding film <NUM> of the pixel on the right side and then diffusely reflected within the image sensor <NUM>. This diffuse reflection might cause flare or color mixing into adjacent pixels.

In addition, since half of the photodiode <NUM> is shielded from light by the light-shielding film <NUM> in the conventional phase difference detection pixel, sufficient SNR cannot be obtained under low illuminance and phase difference detection might not be performed accurately.

Furthermore, although the output of the phase difference detection pixel is also used for the generation of an image as described above, since the output of the phase difference detection pixel is smaller than the output of an imaging pixel for the above reason, it has been necessary to correct the output of the phase difference detection pixel based on the output of imaging pixels around the phase difference detection pixel.

In contrast, with the structure of the phase difference detection pixel of the present technology, part of incident light L1 is transmitted through the organic photoelectric conversion film <NUM> of the pixel on the left side, partly being absorbed thereby, and reflected by the light-shielding film <NUM>, then being absorbed by the organic photoelectric conversion film <NUM> again. Similarly, part of incident light R1 is transmitted through the organic photoelectric conversion film <NUM> of the pixel on the right side, partly being absorbed thereby, and reflected by the light-shielding film <NUM>, then being absorbed by the organic photoelectric conversion film <NUM> again. This structure can reduce diffused reflection of incident light within the image sensor <NUM> and prevent flare or color mixing into adjacent pixels.

In addition, since incident light, which is conventionally blocked out, is subjected to photoelectric conversion by the organic photoelectric conversion film <NUM> in the phase difference detection pixel of the present technology, the output of the organic photoelectric conversion film <NUM> can be obtained in addition to the output of the photodiode <NUM>. Thus, sufficient SNR can be obtained even under low illuminance and phase difference detection can be performed accurately.

Since incident light that is transmitted through the organic photoelectric conversion film <NUM> and reflected by the light-shielding film <NUM> enters the organic photoelectric conversion film <NUM> again, the efficiency of photoelectric conversion in the organic photoelectric conversion film <NUM> can be increased. This increase further improves the accuracy of phase difference detection. In addition, in the case where the organic photoelectric conversion film <NUM> can provide sufficient output even with a small thickness, the height of the image sensor <NUM> can be lowered, which contributes to improved sensitivity of the photodiode <NUM>.

Furthermore, since the output of the organic photoelectric conversion film <NUM> can be obtained in addition to the output of the photodiode <NUM>, there is no need to correct the output of the phase difference detection pixel based on the output of imaging pixels around the phase difference detection pixel.

Here, phase difference AF processing executed by the imaging apparatus <NUM> is described with reference to the flowchart in <FIG>. The phase difference AF processing is executed before imaging processing, which is executed by the imaging apparatus <NUM> at the time of capturing an image of an object.

First, in step S <NUM>, the image sensor <NUM> photoelectrically converts incident light of each pixel, reads pixel signals, and supplies the pixel signals to the A/D conversion section <NUM>.

In step S102, the A/D conversion section <NUM> performs A/D conversion on the pixel signals from the image sensor <NUM>, and supplies the resulting pixel signals to the clamp section <NUM>.

In step S103, the clamp section <NUM> subtracts a black level that is detected in an optical black (OPB) region provided outside an effective pixel region from the pixel signals (pixel values) from the A/D conversion section <NUM>. The clamp section <NUM> supplies the image data (pixel values) output from the phase difference detection pixels, among the image data from which the black level has been subtracted, to the phase difference detection section <NUM>.

In step S104, the phase difference detection section <NUM> performs phase difference detection processing based on the image data from the clamp section <NUM> to perform focusing determination. The phase difference detection processing is performed by using a difference in output between pixels where the light-receiving surfaces are shielded from light on opposite sides, like the phase difference detection pixels P1 and P2 illustrated in <FIG>.

Conventionally, when the outputs of the photodiodes <NUM> in the conventional phase difference detection pixels P1 and P2 illustrated on the left side in <FIG> are expressed as PhasePixel_P1 and PhasePixel_P2, respectively, a phase difference Phase_Diff to be detected is calculated based on, for example, the following formulas (<NUM>) and (<NUM>). <NUM>] <MAT>
[Math. <NUM>] <MAT>.

In contrast, in the present technology, when the outputs of the photodiodes <NUM> in the phase difference detection pixels P1 and P2 of the present technology illustrated on the right side in <FIG> are expressed as PhasePixel_P1 and PhasePixel_P2, respectively, and the outputs of the organic photoelectric conversion films <NUM> are expressed as PhasePixel_Organic1 and PhasePixel_Organic2, respectively, a phase difference Phase_Diffto be detected is calculated based on, for example, the following formulas (<NUM>), (<NUM>), and (<NUM>). <NUM>] <MAT>
[Math. <NUM>] <MAT>
[Math. <NUM>] <MAT>.

In addition, in the present technology, it is also possible to calculate a difference Phase_Diff_A between the outputs of the photodiodes <NUM> of the phase difference detection pixels P1 and P2 and a difference Phase_Diff_B between the outputs of the organic photoelectric conversion films <NUM> of the phase difference detection pixels P1 and P2 based on the following formulas (<NUM>) and (<NUM>), determine the certainty of each of them, for example, and set one of Phase_Diff_A and Phase_Diff_B as a phase difference. <NUM>] <MAT>
[Math. <NUM>] <MAT>.

In the above formulas (<NUM>) to (<NUM>), the output values of the photodiodes <NUM> and the organic photoelectric conversion films <NUM> of the respective phase difference detection pixels P1 and P2 are used as they are as PhasePixel_P1 and PhasePixel_P2 and PhasePixel_Organic1 and PhasePixel_Organic2; however, it is also possible to use these outputs to which a gain is applied by using a predetermined coefficient. Furthermore, the phase difference calculated by using the output values of the photodiodes <NUM> and the organic photoelectric conversion films <NUM> of the respective phase difference detection pixels P1 and P2 is not limited to those calculated based on the above formulas (<NUM>) to (<NUM>), and may be calculated by application of another computation.

As described above, in the conventional phase difference detection pixels, only the outputs of the photodiodes <NUM> of the respective two pixels can be used for phase difference detection. In the phase difference detection pixels of the present technology, in addition to the outputs of the photodiodes <NUM> of the respective two pixels, the outputs of the organic photoelectric conversion films <NUM> of the respective pixels can be used for phase difference detection.

When the phase difference detection processing is performed in this way and focusing determination is performed, the phase difference detection section <NUM> supplies the focusing determination result to the lens control section <NUM>.

In step S105, the lens control section <NUM> controls the driving of the lens <NUM> based on the focusing determination result from the phase difference detection section <NUM>.

According to the above-described processing, in addition to the outputs of the photodiodes <NUM> of the respective two pixels, the outputs of the organic photoelectric conversion films <NUM> of the respective pixels can be used for phase difference detection; therefore, the signal amount used for the phase difference detection can be increased. Thus, sufficient SNR can be obtained even under low illuminance and phase difference detection can be performed accurately. As a result, higher-quality images which are not out of focus can be obtained.

Next, imaging processing executed by the imaging apparatus <NUM> is described with reference to the flowchart in <FIG>.

Here, the processing of steps S201 to S203 of the flowchart in <FIG> is the same as the processing of steps S101 to S103 of the flowchart in <FIG>, and therefore is not repeatedly described. Note that in step S203, the clamp section <NUM> supplies the image data (pixel values) from which the black level has been subtracted for all the pixels to the defect correction section <NUM>.

In step S204, based on the image data from the clamp section <NUM>, the defect correction section <NUM> performs correction of pixel values (defect correction) on defective pixels where correct pixel values cannot be obtained, that is, phase difference detection pixels.

In the conventional phase difference detection pixel, only the output of the photodiode <NUM>, which is shielded from light, can be obtained as its output (pixel value). Therefore, as a technique for defect correction of the phase difference detection pixel, the output of a phase difference detection pixel P targeted for correction is replaced based on the output of a same-color pixel around the phase difference detection pixel P as illustrated in <FIG>, for example.

In the above technique, however, since the pixel value of the correction target is replaced with a value based on the output of a pixel around the correction target, the original pixel value of the phase difference detection pixel P is completely ignored. This ignorance is equivalent to a decrease in resolution and might degrade the image quality.

In contrast, in the phase difference detection pixel of the present technology, in addition to the output of the photodiode <NUM>, which is shielded from light, the output of the organic photoelectric conversion film <NUM> is obtained as its output (pixel value). Thus, by estimating the output corresponding to the blocked out light by using the output of the organic photoelectric conversion film <NUM>, a pixel value P1_Out of the phase difference detection pixel P1 after defect correction is calculated based on, for example, the following formula (<NUM>). <NUM>] <MAT>.

In the formula (<NUM>), α and β are coefficients decided depending on a difference in sensitivity between the photodiode <NUM> and the organic photoelectric conversion film <NUM>.

According to the formula (<NUM>), the original pixel value of the phase difference detection pixel P1 can be used as the pixel value of the correction target; therefore, a decrease in resolution can be suppressed, leading to improved image quality.

The pixel value of the phase difference detection pixel after the defect correction is not limited to that calculated based on the above formula (<NUM>), and may be calculated by application of another computation.

The image data subjected to the correction of defective pixels in this manner is supplied to the demosaic section <NUM>.

In step S205, the demosaic section <NUM> performs demosaic processing to convert RAW data to RGB data, and supplies the RGB data to the LM/WB/gamma correction section <NUM>.

In step S206, the LM/WB/gamma correction section <NUM> performs color correction, adjustment of white balance, and gamma correction on the RGB data from the demosaic section <NUM>, and supplies the resulting data to the luminance chroma signal generation section <NUM>.

In step S207, the luminance chroma signal generation section <NUM> generates a luminance signal and chroma signals (YCrCb data) from the RGB data.

In step S208, the I/F section <NUM> outputs the luminance signal and chroma signals generated by the luminance chroma signal generation section <NUM> to an external storage device or display device, and the imaging processing is ended.

According to the above-described processing, the output corresponding to the blocked out light can be estimated and the original pixel value of the phase difference detection pixel can be used in the defect correction of the phase difference detection pixel. Therefore, a decrease in resolution can be suppressed, leading to improved image quality; thus, higher-quality images can be obtained.

In the phase difference detection pixel illustrated in <FIG>, when the attenuation factor of light with a wavelength to be photoelectrically converted by the organic photoelectric conversion film <NUM> (transmission wavelength of the color filter <NUM>) is sufficient, a part of the light-shielding film <NUM> that shields half of the photodiode <NUM> may be omitted as illustrated in <FIG>.

Such a structure can reduce diffuse reflection of light reflected by the light-shielding film <NUM> and prevent flare or color mixing into adjacent pixels. Furthermore, in the case where the light-shielding film <NUM> is completely omitted, the number of manufacturing steps can be reduced.

The organic photoelectric conversion film <NUM> may be provided below the light-shielding film <NUM> and the color filter <NUM>.

According to the above description, phase difference detection is performed using differences between the photoelectric conversion layers (the photodiodes <NUM> and the organic photoelectric conversion films <NUM>) in the phase difference detection pixels. Alternatively, phase difference detection may be performed using differences between the outputs of photoelectric conversion layers in phase difference detection pixels and the outputs of imaging pixels arranged around the phase difference detection pixels.

<FIG> is a cross-sectional view illustrating another example structure of phase difference detection pixels of the present technology.

The cross-sectional view in <FIG> differs from the cross-sectional view in <FIG> in that imaging pixels P2 and P3 are arranged between phase difference detection pixels P1 and P4 and that the color filter <NUM> is not formed in the same layer as the light-shielding film <NUM> but formed above the organic photoelectric conversion film <NUM>.

In the case where the image sensor <NUM> includes pixels with the structure illustrated in <FIG>, phase difference detection processing is performed using the outputs of the phase difference detection pixels and the outputs of the adjacent imaging pixels.

Specifically, based on the following formulas (<NUM>) to (<NUM>), a difference Phase_Diff_A between the outputs of the organic photoelectric conversion films <NUM> of the phase difference detection pixels P1 and P4, a difference Phase_Diff_B between the outputs of the photodiodes <NUM> of the imaging pixel P2 and the phase difference detection pixel P1, and a difference Phase_Diff_C between the outputs of the photodiodes <NUM> of the imaging pixel P3 and the phase difference detection pixel P4 are calculated, and a predetermined computation is performed on each of the differences to calculate the final phase difference. <NUM>] <MAT>
[Math. <NUM>] <MAT>
[Math. <NUM>] <MAT>.

Note that α in the formula (<NUM>) and β in the formula (<NUM>) are coefficients decided depending on a decrease in sensitivity due to light shielding by the light-shielding film <NUM> in the phase difference detection pixels P1 and P4.

As described above, in the phase difference detection processing, it is possible to use not only differences in output between the phase difference detection pixels but also differences between the outputs of photoelectric conversion layers in the phase difference detection pixels and the outputs of the imaging pixels arranged around the phase difference detection pixels.

<FIG> is a cross-sectional view illustrating further another example structure of phase difference detection pixels of the present technology.

In each of the phase difference detection pixels illustrated in <FIG>, photodiodes <NUM>-<NUM> to <NUM>-<NUM> as photoelectric conversion sections are formed in the semiconductor substrate <NUM>. Above the semiconductor substrate <NUM>, organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are formed. In addition, the on-chip lens <NUM> is formed above organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>.

Each phase difference detection pixel illustrated in <FIG> is provided with one on-chip lens <NUM> and a plurality of photoelectric conversion layers formed below the on-chip lens <NUM>, specifically, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> and the photodiodes <NUM>-<NUM> to <NUM>-<NUM> from the top. The organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are formed separately with respect to the light-receiving surface (hereinafter described as being separately formed). The photodiodes <NUM>-<NUM> to <NUM>-<NUM> are formed as two layers in the cross-sectional height direction and are separately formed in each layer.

Note that techniques for forming a plurality of photodiodes in the cross-sectional height direction are disclosed in <CIT> and <CIT>, for example.

In the phase difference detection pixel illustrated in <FIG>, the photoelectric conversion layers, that is, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> in the top layer, the photodiodes <NUM>-<NUM> and <NUM>-<NUM> in the second layer from the top, and the photodiodes <NUM>-<NUM> and <NUM>-<NUM> in the third layer from the top, photoelectrically convert light with the respective different wavelengths. For example, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert green light, the photodiodes <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert blue light, and the photodiodes <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert red light.

Here, in one phase difference detection pixel, the photodiodes <NUM>-<NUM> and <NUM>-<NUM> and the organic photoelectric conversion film <NUM>-<NUM> formed on the left side in the figure are called a unit <NUM>, and the photodiodes <NUM>-<NUM> and <NUM>-<NUM> and the organic photoelectric conversion film <NUM>-<NUM> formed on the right side in the figure are called a unit <NUM>.

In the case where the image sensor <NUM> includes phase difference detection pixels with the structure illustrated in <FIG>, phase difference detection processing is performed using a difference between the output of the unit <NUM> and the output of the unit <NUM>.

Specifically, when the outputs of the photodiodes <NUM>-<NUM> to <NUM>-<NUM> in the phase difference detection pixel illustrated in <FIG> are expressed as PhotoDiode <NUM> to PhotoDiode4, respectively, and the outputs of the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are expressed as Organic1 and Organic2, respectively, a phase difference Phase_Diff to be detected is calculated based on, for example, the following formulas (<NUM>), (<NUM>), (<NUM>), and (<NUM>). <NUM>] <MAT>
[Math. <NUM>] <MAT>
[Math. <NUM>] <MAT>
[Math. <NUM>] <MAT>.

In addition, it is also possible to calculate a difference Phase_Diff_A between the outputs of the photodiodes <NUM>-<NUM> and <NUM>-<NUM>, a difference Phase_Diff_B between the outputs of the photodiodes <NUM>-<NUM> and <NUM>-<NUM>, and a difference Phase_Diff_C between the outputs of the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> based on the following formulas (<NUM>), (<NUM>), and (<NUM>), determine the certainty of each of them, for example, and set one of Phase_Diff_A, Phase_Diff_B, and Phase_Diff_C as a phase difference. <NUM>] <MAT>
[Math. <NUM>] <MAT>
[Math. <NUM>] <MAT>.

Since Phase_Diff_A, Phase_Diff_B, and Phase_Diff_C are phase differences for the respective color components, it is also possible to determine the illumination environment or the color of an object and set one of Phase_Diff_A, Phase_Diff_B, and Phase_Diff_C as a phase difference.

Furthermore, it is also possible to weight Phase_Diff_A, Phase_Diff_B, and Phase_Diff_C by using at least one or all of the above certainty, illumination environment, and color of an object to calculate the final phase difference.

In the above formulas (<NUM>) to (<NUM>), the output values of the photodiodes <NUM>-<NUM> to <NUM>-<NUM> and the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> of the phase difference detection pixel are used as they are as PhotoDiode1 to PhotoDiode4 and Organic1 and Organic2; however, it is also possible to use these outputs to which a gain is applied by using a predetermined coefficient.

With the structure of the phase difference detection pixel illustrated in <FIG>, phase difference detection can be performed using a difference in output between the plurality of photoelectric conversion layers, and optical loss can be made extremely small because a light-shielding film and a color filter are not provided. Thus, sufficient SNR can be obtained even under low illuminance and phase difference detection can be performed accurately.

In addition, when variation in manufacture occurs in the cross-sectional height direction in the phase difference detection pixel illustrated in <FIG>, even if the output of any of the plurality of photoelectric conversion layers (e.g., the photodiodes <NUM>-<NUM> and <NUM>-<NUM>) gets unreliable, the output of another photoelectric conversion layer can be used; therefore, robustness to variation in manufacture can be ensured.

Although the organic photoelectric conversion films are separately formed in the phase difference detection pixel illustrated in <FIG>, an organic photoelectric conversion film <NUM> which is not separately formed may be used as illustrated in <FIG>.

Furthermore, in the structure illustrated in <FIG>, when the spectral properties of the organic photoelectric conversion film <NUM> are insufficient, a color filter <NUM> may be provided below the organic photoelectric conversion film <NUM> as illustrated in <FIG>. Alternatively, as illustrated in <FIG>, the color filter <NUM> may be provided in place of the organic photoelectric conversion film <NUM>.

In the above cases, phase difference detection processing is performed using a difference between the output of the unit <NUM> including the photodiodes <NUM>-<NUM> and <NUM>-<NUM> and the output of the unit <NUM> including the photodiodes <NUM>-<NUM> and <NUM>-<NUM>.

The sum of the outputs of the unit <NUM> and the unit <NUM> in the above phase difference detection pixel is equal to the output of a normal imaging pixel. That is, the pixel structures illustrated in <FIG> can also be applied to imaging pixels. Accordingly, the pixel structures illustrated in <FIG> may be applied to all the pixels in the image sensor <NUM>.

In each of the phase difference detection pixels illustrated in <FIG>, organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are formed above the semiconductor substrate <NUM>. Organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are formed above the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>. Organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are formed above the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>. In addition, the on-chip lens <NUM> is formed above the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>.

Each phase difference detection pixel illustrated in <FIG> is provided with one on-chip lens <NUM> and a plurality of photoelectric conversion layers formed below the on-chip lens <NUM>, specifically, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>, and the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> from the top. The organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM>, and the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> are separately formed with respect to the light-receiving surface in the respective layers.

In the phase difference detection pixel illustrated in <FIG>, the photoelectric conversion layers, that is, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> in the top layer, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> in the second layer from the top, and the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> in the third layer from the top, photoelectrically convert light with the respective different wavelengths. For example, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert green light, the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert blue light, and the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> photoelectrically convert red light.

Even in the case where the image sensor <NUM> includes phase difference detection pixels with the structure illustrated in <FIG>, phase difference detection processing is performed in a manner similar to that with phase difference detection pixels with the structure illustrated in <FIG>.

Although the organic photoelectric conversion films are separately formed in all the three layers in the phase difference detection pixel illustrated in <FIG>, it is also possible to separately form only the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> in the top layer and provide a light-shielding film <NUM> below the organic photoelectric conversion films <NUM>-<NUM> and <NUM>-<NUM> to partially block out light that enters organic photoelectric conversion films <NUM> and <NUM>, which are below the light-shielding film <NUM>, as illustrated in <FIG>.

Furthermore, as illustrated in <FIG>, a photodiode <NUM> formed in the semiconductor substrate <NUM> may be provided in place of the organic photoelectric conversion film <NUM> in the bottom layer in the phase difference detection pixel illustrated in <FIG>.

<FIG> is a block diagram illustrating an example configuration of an imaging apparatus of a second embodiment of the present technology.

An imaging apparatus <NUM> illustrated in <FIG> includes the lens <NUM>, the optical filter <NUM>, an image sensor <NUM>, the A/D conversion section <NUM>, the clamp section <NUM>, a color mixing subtraction section <NUM>, the demosaic section <NUM>, the LM/WB/gamma correction section <NUM>, the luminance chroma signal generation section <NUM>, and the I/F section <NUM>.

Note that in the imaging apparatus <NUM> of <FIG>, constituents having functions similar to those of the constituents provided in the imaging apparatus <NUM> of <FIG> are denoted by the same designations and the same numerals, and description of such constituents is omitted as appropriate.

In the image sensor <NUM>, unlike in the image sensor <NUM> provided in the imaging apparatus <NUM> of <FIG>, no phase difference detection pixels are arranged and only imaging pixels are arranged. In other words, the imaging apparatus <NUM> performs photographing processing without performing phase difference AF processing.

The color mixing subtraction section <NUM> subtracts a color mixing component, which is a light component having been transmitted through filters of peripheral pixels, from image data from the clamp section <NUM>. The color mixing subtraction section <NUM> supplies the image data from which the color mixing component has been subtracted to the demosaic section <NUM>.

<FIG> is a cross-sectional view illustrating an example structure of imaging pixels of the present technology.

In each of the imaging pixels illustrated in <FIG>, a photodiode <NUM> as a photoelectric conversion section is formed in a semiconductor substrate <NUM>. Above the semiconductor substrate <NUM>, a light-shielding film <NUM> and a color filter <NUM> are formed in the same layer, and above them, specifically, right above the light-shielding film <NUM>, an organic photoelectric conversion film <NUM> is formed. In addition, an on-chip lens <NUM> is formed above the organic photoelectric conversion film <NUM>.

Each imaging pixel illustrated in <FIG> is provided with one on-chip lens <NUM> and a plurality of photoelectric conversion layers formed below the on-chip lens <NUM>, specifically, the organic photoelectric conversion film <NUM> and the photodiode <NUM> from the top. The organic photoelectric conversion film <NUM> is partially formed with respect to the light-receiving surface. Specifically, the organic photoelectric conversion film <NUM> is formed at the boundary part between adjacent imaging pixels as illustrated in <FIG>. In addition, in the photodiode <NUM>, the boundary part between adjacent imaging pixels is partially shielded from light by the light-shielding film <NUM>.

Next, referring to <FIG>, a conventional imaging pixel and an imaging pixel of the present technology are compared in structure.

The conventional imaging pixel illustrated on the left side in <FIG> differs from the imaging pixel of the present technology illustrated on the right side in <FIG> in that the organic photoelectric conversion film <NUM> is not provided.

With the structure of the conventional imaging pixel, in the case where incident light L that has been transmitted through the on-chip lens <NUM> in the pixel on the left side enters the photodiode <NUM> in the pixel on the right side, the amount of light that has entered cannot be detected, which makes it difficult to correct a color mixing component with respect to the output of the pixel on the right side. This difficulty might adversely affect color reproducibility and SNR.

In contrast, with the structure of the imaging pixel of the present technology, in the case where incident light L that has been transmitted through the on-chip lens <NUM> in the pixel on the left side enters the photodiode <NUM> in the pixel on the right side, the amount of light that has entered can be estimated based on the output of the organic photoelectric conversion film <NUM>, which makes it possible to correct a color mixing component with respect to the output of the pixel on the right side.

The processing of steps S301 to S303 and S305 to S308 of the flowchart in <FIG> is the same as the processing of steps S201 to S203 and S205 to S208 of the flowchart in <FIG>, and therefore is not repeatedly described. Note that in step S203, the clamp section <NUM> supplies the image data (pixel values) from which the black level has been subtracted for all the pixels to the color mixing subtraction section <NUM>.

In step S304, the color mixing subtraction section <NUM> performs color mixing subtraction processing to subtract a color mixing component from image data from the clamp section <NUM>, and supplies the resulting data to the demosaic section <NUM>.

Specifically, the color mixing subtraction section <NUM> estimates the color mixing component by using the output of the organic photoelectric conversion film <NUM>, and thereby calculates a pixel value P_Out of the imaging pixel after color mixing correction based on the following formula (<NUM>). <NUM>] <MAT>.

In the formula (<NUM>), PhotoDiode_Out indicates the output of the photodiode <NUM>, Organic_Out indicates the output of the organic photoelectric conversion film <NUM>, and α is a coefficient that is set arbitrarily. For example, the value of α may be adjusted depending on whether or not the pixel targeted for color mixing correction is close to an edge of the angle of view.

The pixel value P_Out of the imaging pixel after color mixing correction is not limited to that calculated based on the formula (<NUM>), and may be calculated by application of another computation. For example, it is possible to perform a computation in accordance with the color of the pixel of interest targeted for color mixing correction, or perform a computation by using the output of the photodiode <NUM> of an imaging pixel adjacent to the pixel of interest in addition to the output of the organic photoelectric conversion film <NUM>.

The image data from which the color mixing component has been subtracted in this manner is supplied to the demosaic section <NUM>.

According to the above-described processing, in color mixing correction of the imaging pixel, the output corresponding to light resulting from color mixing can be estimated based on the output of the organic photoelectric conversion film <NUM>, which makes it possible to correct a color mixing component with respect to the output of the pixel of interest, leading to improved image quality; thus, higher-quality images can be obtained.

Note that although the organic photoelectric conversion film <NUM> is described as being formed at the boundary part between the imaging pixels, the organic photoelectric conversion film <NUM> may be formed as one continuous film with respect to the effective pixel region, or may be formed every <NUM>×<NUM> pixels, for example. Furthermore, for example, the width of the organic photoelectric conversion film <NUM> at the boundary part between the imaging pixels, the position where the organic photoelectric conversion film <NUM> is formed, and the kind (material) of the organic photoelectric conversion film <NUM> may be changed in accordance with the kind of the color mixing component to be detected.

In conventional imaging apparatuses, the illumination environment (a light source such as a fluorescent lamp or a light bulb) at the time of imaging is estimated, and image creation is performed in accordance with the illumination environment. In recent years, however, new light sources such as light emitting diode (LED) light sources have spread. Under this circumstance, since only color signals of three colors can be obtained with an image sensor in which R, G, and B pixels are arranged in the Bayer array, it has become difficult to estimate the light source.

In view of this, an imaging apparatus capable of light source estimation with improved accuracy is described below.

<FIG> is a block diagram illustrating an example configuration of an imaging apparatus of a third embodiment of the present technology.

An imaging apparatus <NUM> illustrated in <FIG> includes the lens <NUM>, the optical filter <NUM>, the image sensor <NUM>, the A/D conversion section <NUM>, the clamp section <NUM>, the color mixing subtraction section <NUM>, the demosaic section <NUM>, the LM/WB/gamma correction section <NUM>, the luminance chroma signal generation section <NUM>, the I/F section <NUM>, and a light source estimation section <NUM>.

The light source estimation section <NUM> estimates a light source illuminating an object from RGB data from the demosaic section <NUM>, and supplies the estimation result to the LM/WB/gamma correction section <NUM>.

The processing of steps S401 to S405, S408, and S409 of the flowchart in <FIG> is the same as the processing of steps S301 to S305, S307, and S308 of the flowchart in <FIG>, and therefore is not repeatedly described. Note that in step S405, the demosaic section <NUM> supplies the image data (RGB data) after the demosaic processing also to the light source estimation section <NUM>.

In step S406, the light source estimation section <NUM> performs light source estimation with respect to the RGB data from the demosaic section <NUM>.

Specifically, the light source estimation section <NUM> performs light source estimation by using the output of the photodiode <NUM> and the output of the organic photoelectric conversion film <NUM> as the RGB data for each imaging pixel.

Conventionally, when light source estimation is performed by using the output ratios of R/G and B/G, for example, the output ratios of R/G and B/G do not always vary even if a light source A and a light source B with different spectral outputs are present. Specifically, the output of a pixel is not a value obtained for each wavelength but is an integral element determined by, for example, the product of the spectral properties of an image sensor and a light source; therefore, the light source cannot be determined when the output of each wavelength varies but the integral value is identical.

In contrast, in the light source estimation section <NUM>, new spectral properties can be obtained in the organic photoelectric conversion film <NUM>. Therefore, even if the output ratios of R/G and B/G are equivalent in the photodiode <NUM>, for example, the spectral properties can be separated based on a difference in the output of the organic photoelectric conversion film <NUM>, which results in improved accuracy of light source estimation. In particular, the configuration of the image sensor <NUM>, which makes it possible to obtain the output from the organic photoelectric conversion film <NUM> without decreasing the number of pixels, improves the accuracy of light source estimation without lowering resolution.

The estimation result of the light source estimation performed in this manner is supplied to the LM/WB/gamma correction section <NUM>.

In step S407, the LM/WB/gamma correction section <NUM> performs color correction, adjustment of white balance, and gamma correction on the RGB data from the demosaic section <NUM> based on the estimation result from the light source estimation section <NUM>. Specifically, the LM/WB/gamma correction section <NUM> decides a matrix coefficient used for the color correction, sets a gain for adjusting the white balance, and decides a gamma curve used for the gamma correction by using the estimation result from the light source estimation section <NUM>.

According to the above-described processing, light source estimation can be performed by using the output of the organic photoelectric conversion film <NUM> in addition to the output of the photodiode <NUM>, which improves the accuracy of the light source estimation, leading to improved image quality; thus, higher-quality images can be obtained.

As in an imaging apparatus <NUM> illustrated in <FIG>, the light source estimation section <NUM> may be provided in the imaging apparatus <NUM> (<FIG>), which performs phase difference detection. With this configuration, even if the normal imaging pixel is saturated and a correct RGB ratio cannot be obtained when an image of a bright object is captured, the phase difference detection pixel in which half of the photodiode is shielded from light is not saturated and a correct RGB ratio can be obtained. This configuration allows accurate light source estimation.

Furthermore, in this case, new spectral properties can be obtained in the organic photoelectric conversion film <NUM> in the phase difference detection pixel illustrated in <FIG>, for example. Therefore, even if the output ratios of R/G and B/G are equivalent in the photodiode <NUM>, the spectral properties can be separated based on a difference in the output of the organic photoelectric conversion film <NUM>, which results in improved accuracy of light source estimation. Using the outputs of a plurality of photoelectric conversion layers with different spectral properties in this manner allows accurate light source estimation.

Pixels arranged in the image sensor <NUM> provided in an imaging apparatus that performs color mixing correction do not necessarily have the structure illustrated in <FIG>, and may have the structure illustrated in <FIG>, for example.

<FIG> is a cross-sectional view illustrating another example structure of imaging pixels of the present technology.

<FIG> illustrates cross sections of color mixing detection pixels P1 and P2 for detecting color mixing and normal imaging pixels P3 and P4.

As illustrated in <FIG>, in each of the color mixing detection pixels P1 and P2, a photodiode <NUM> as a photoelectric conversion section is formed in a semiconductor substrate <NUM>. Above the semiconductor substrate <NUM>, a light-shielding film <NUM> is formed, and an organic photoelectric conversion film <NUM> is partially formed above the light-shielding film <NUM>. In addition, an on-chip lens <NUM> is formed above the organic photoelectric conversion film <NUM>.

In each of the imaging pixels P3 and P4, the photodiode <NUM> as a photoelectric conversion section is formed in the semiconductor substrate <NUM>. Above the semiconductor substrate <NUM>, the light-shielding film <NUM> and a color filter <NUM> are formed in the same layer, and above them, the on-chip lens <NUM> is formed.

Each color mixing detection pixel illustrated in <FIG> is provided with one on-chip lens <NUM> and a plurality of photoelectric conversion layers formed below the on-chip lens <NUM>, specifically, the organic photoelectric conversion film <NUM> and the photodiode <NUM> from the top. The organic photoelectric conversion film <NUM> is partially formed with respect to the light-receiving surface. The photodiode <NUM> is shielded from light by the light-shielding film <NUM> at the entire light-receiving surface.

However, as illustrated in <FIG>, part of light that has entered the imaging pixel P3 proceeds into the photodiode <NUM> of the color mixing detection pixel P2. That is, the photodiode <NUM> of the color mixing detection pixel P2 can output only a color mixing component from the adjacent imaging pixel P3. Note that the photodiode <NUM> of the color mixing detection pixel P2 can be regarded as being partially shielded from light because it receives light from the adjacent imaging pixel P3.

In view of this, as in the technique disclosed in <CIT>, for example, the color mixing subtraction section <NUM> of the imaging apparatus <NUM> in <FIG> may estimate the amount of color mixing in the normal imaging pixel by using the output of the photodiode <NUM> of the color mixing detection pixel and subtract the estimated value from the output of the imaging pixel.

Alternatively, the color mixing detection pixels P1 and P2 illustrated in <FIG> may be provided in the image sensor <NUM> of the imaging apparatus <NUM> in <FIG> and phase difference detection may be performed by using a difference in output between the organic photoelectric conversion films <NUM> of the respective color mixing detection pixels P1 and P2.

Although the phase difference detection pixels are arranged to be distributed among the plurality of imaging pixels arranged two-dimensionally in a matrix form in the image sensor <NUM> in <FIG>, all the pixels may be phase difference detection pixels. In that case, the imaging apparatus needs to be provided with separate image sensors for phase difference AF and imaging.

<FIG> is a block diagram illustrating an example configuration of an imaging apparatus of a fourth embodiment of the present technology.

An imaging apparatus <NUM> illustrated in <FIG> includes the lens <NUM>, the optical filter <NUM>, an AF image sensor <NUM>, an A/D conversion section <NUM>, the phase difference detection section <NUM>, the lens control section <NUM>, an image sensor <NUM>, the A/D conversion section <NUM>, the clamp section <NUM>, the demosaic section <NUM>, the LM/WB/gamma correction section <NUM>, the luminance chroma signal generation section <NUM>, and the I/F section <NUM>.

In the AF image sensor <NUM>, unlike in the image sensor <NUM> provided in the imaging apparatus <NUM> of <FIG>, no imaging pixels are arranged, and only the phase difference detection pixels illustrated in <FIG>, for example, are arranged.

The A/D conversion section <NUM> converts electrical signals (analog signals) of RGB supplied from the AF image sensor <NUM> to digital data (image data) and supplies the digital data to the phase difference detection section <NUM>.

In the image sensor <NUM>, unlike in the image sensor <NUM> provided in the imaging apparatus <NUM> of <FIG>, no phase difference detection pixels are arranged and only normal imaging pixels are arranged.

According to the above-described configuration, there is no need to provide phase difference detection pixels in the image sensor <NUM> used in normal imaging, which eliminates the need to perform defect correction on phase difference detection pixels. Furthermore, the AF image sensor <NUM> and the image sensor <NUM> can be manufactured as separate image sensors and thus can be manufactured by the respective optimized processes.

Alternatively, in the imaging apparatus <NUM> of <FIG>, it is possible to provide the image sensor <NUM> in place of the image sensor <NUM> and provide the color mixing subtraction section <NUM> so that color mixing subtraction processing can be performed.

Furthermore, although the AF image sensor <NUM> is provided in the imaging apparatus <NUM> of <FIG>, an image sensor for color mixing subtraction or an image sensor for light source estimation may be provided.

In the above embodiments, in the configuration in which one pixel includes an organic photoelectric conversion film and a photodiode, the organic photoelectric conversion film and the photodiode may have different exposure values (shutter/gain). For example, the frame rate of the photodiode is set to <NUM> fps and the frame rate of the organic photoelectric conversion film is set to <NUM> fps.

Even in the case where the frame rate of the organic photoelectric conversion film is lowered and accumulation time is increased in this manner, the normal output from the photodiode is not influenced.

In addition, in the above embodiments, the on-chip lens or the color filter of each pixel of the image sensor may be shrunk so that exit pupil correction can be performed. Thus, shading is corrected, which leads to improved sensitivity.

Claim 1:
An image sensor (<NUM>, <NUM>, <NUM>) comprising a plurality of phase difference detection pixels for performing auto focus (AF) by phase difference detection, each phase difference detection pixel comprising
one on-chip lens (<NUM>), and
a plurality of photoelectric conversion layers (<NUM>, <NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>) formed vertically stacked below the on-chip lens (<NUM>),
wherein an organic photoelectric conversion film (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) is the top photoelectric conversion layer among the plurality of photoelectric conversion layers;
characterized in that
the organic photoelectric conversion film includes a first portion and a second portion vertically stacked below the on-chip lens and at the same level as the top photoelectric conversion layer, and in that the image sensor is configured to use, for the phase difference detection, a difference in output between the first portion of the organic photoelectric conversion film (<NUM>-<NUM>, <NUM>-<NUM>) and the second portion of the organic photoelectric conversion film (<NUM>-<NUM>, <NUM>-<NUM>).