Solid-state imaging devices and camera equipment

Abstract

A solid-state imaging device including a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels, Each of the first pixels and the second pixels is One or more photoelectric conversion elements that configure the light receiving surface of the pixel and generate electric charges by photoelectrically converting received light; a floating diffusion connected to the one or more photoelectric conversion elements and converting the electric charge into a voltage corresponding to the amount of the electric charge; a storage capacitor connected to the floating diffusion and capable of storing the charge overflowing from the one or more photoelectric conversion elements; Equipped with Each of the plurality of first pixels includes two or more of the photoelectric conversion elements, the floating diffusion is connected to all of the two or more photoelectric conversion elements, and is configured to generate a phase difference data signal by comparing the charges accumulated in the two or more photoelectric conversion elements, Two or more of the second pixels among the plurality of second pixels together constitute a second pixel set; A solid-state imaging device, wherein the second set of pixels is configured to generate a phase difference data signal by comparing the charges accumulated in each of the second pixels constituting the second set of pixels.

Description

[Technical field]

[0001] The present invention relates to a solid-state imaging device and a camera device equipped with the solid-state imaging device. [Background technology]

[0002] In recent years, high dynamic range imaging (HDR imaging) technology has been known as a technology for realizing an input dynamic range that exceeds the allowable range of the storage capacity that can be held in a photodiode (photoelectric conversion element) provided in a pixel in camera devices such as digital cameras. For example, Patent Document 1 discloses an "overflow charge storage capacitance type" HDR imaging technology that can hold charges that greatly exceed the upper limit of the storage capacity that can be held in the photodiode in the pixel by storing charges that overflow from the photodiode in an additional storage capacitance provided in the pixel.

[0003] In addition, in recent camera devices, there is an increasing demand for high-speed and high-precision autofocus. As a technology for such autofocus, image plane phase difference autofocus technology is widely adopted, especially in relatively small camera devices such as mirrorless cameras and smartphones. In this image plane phase difference autofocus, the light receiving surface of a pixel under one microlens is divided into two parts, signals from a subject passing through different optical paths are read separately, and the spatial phase difference of the subject image is processed to calculate the defocus amount. In this way, the image plane phase difference autofocus can calculate the defocus amount with a single phase calculation, so it has the advantage of being able to perform autofocus faster than the conventional contrast detection type autofocus.

[0004] Comparing these two image plane phase difference autofocus methods, in the dual pixel method, all pixels can contribute to the creation of phase difference information and the output of an image signal, whereas in the mask method, only masked pixels contribute to the creation of phase difference information, and only unmasked pixels contribute to the output of an image signal. Therefore, typically, the dual pixel method has higher autofocus accuracy and a better signal-to-noise ratio for the captured image than the mask method, especially when capturing a low-luminance subject.

[0005] On the other hand, in the dual pixel method, when shooting a high-luminance subject, one of the two photodiodes arranged in one pixel may generate electric charge exceeding the upper limit of the storage capacity that can be held, and the electric charge overflowing from the photodiode may flow into the other photodiode. In a pixel where such an overflow occurs, the two photodiodes no longer provide accurate phase difference information, which may cause a decrease in the accuracy of the autofocus.

[0006] Attempts are also being made to apply such dual pixel imaging surface phase detection autofocus technology to pixels employing an overflow charge storage capacitance type HDR imaging technology as disclosed in Patent Document 1.

[0007] As an example of such an attempt, in a dual pixel method in which two photodiodes are arranged in one pixel, a method of arranging additional storage capacitors corresponding to each photodiode can be considered. However, arranging multiple additional storage capacitors in a pixel in this way increases the size of the pixel, making it difficult to adopt this method in relatively small camera devices such as the above-mentioned mirrorless cameras and smartphones, and is therefore unrealistic.

[0008] As a means for combining these technologies while suppressing the enlargement of the pixel, Patent Document 2 discloses a pixel having an overflow storage capacitance that is provided in common to two photodiodes (photoelectric conversion units) and can store the charge overflowing from these two photodiodes. In this pixel, the potential barrier between the two photodiodes is set relatively large, and it is designed so that the charge overflowing from one photodiode flows preferentially into the overflow storage capacitance rather than into the other photodiode. The charge thus flowing into the overflow storage capacitance and stored is added to the one of the two photodiodes that has stored the larger charge when generating a phase difference signal. As a result, the pixel of Patent Document 2 can provide accurate phase difference information even if the charge generated exceeds the upper limit of the storage capacity that can be stored in one of the two photodiodes in the pixel. Therefore, the pixel of Patent Document 2 can realize a high dynamic range and can perform autofocus with sufficiently high accuracy even for a subject with a certain degree of high brightness.

[0009] However, in the pixel of Patent Document 2, although it can handle the case where only one of the two photodiodes overflows, when capturing an object with such high brightness that both of the two photodiodes overflow, charges flow from both of the two photodiodes into one overflow holding capacitance. Therefore, the phase information of the charges held in the overflow holding capacitance is lost, resulting in a problem that accurate phase difference information cannot be provided. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] US Patent Application Publication No. 2017 / 0099423 [Patent Document 2] JP 2020-57894 A Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, an object of the present invention is to provide a solid-state imaging device that can realize a high dynamic range while providing phase difference information with high accuracy even for subjects with higher brightness, and a camera device equipped with the solid-state imaging device. [Means for solving the problem]

[0012] The solid-state imaging device according to the present invention comprises: A solid-state imaging device including a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels, Each of the first pixels and the second pixels is One or more photoelectric conversion elements that configure the light receiving surface of the pixel and generate electric charges by photoelectrically converting received light; a floating diffusion connected to the one or more photoelectric conversion elements and converting the electric charge into a voltage corresponding to the amount of the electric charge; a storage capacitor connected to the floating diffusion and capable of storing the charge overflowing from the one or more photoelectric conversion elements; Equipped with Each of the plurality of first pixels includes two or more of the photoelectric conversion elements, the floating diffusion is connected to all of the two or more photoelectric conversion elements, and is configured to generate a phase difference data signal by comparing the charges accumulated in the two or more photoelectric conversion elements, Two or more second pixels among the plurality of second pixels together constitute a set of second pixels; The second set of pixels is configured such that a phase difference data signal can be generated by comparing the charges stored in each of the second pixels constituting the second set of pixels.

[0013] In the solid-state imaging device, for example, in each of the two or more pixels constituting the second pixel set, a part of the light receiving surface of the pixel is masked so as to prevent light reception on the part of the light receiving surface.

[0014] Alternatively, in the solid-state imaging device, each of the plurality of first pixels is independently provided with one on-chip lens (OCL); Each of the second pixel sets is provided with an independent on-chip lens (OCL), and the two or more pixels constituting the second pixel set share the one on-chip lens (OCL).

[0015] In the solid-state imaging device, in each of the plurality of first pixels, The potential barrier between the two or more photoelectric conversion elements is lower than the potential barrier between the photoelectric conversion element and the storage capacitor.

[0016] In this case, preferably, in each of the plurality of second pixels, When the sum of the charges accumulated in the one or more photoelectric conversion elements is equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges accumulated in the one or more photoelectric conversion elements; When the sum of the charges stored in the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges stored in the one or more photoelectric conversion elements and the charges stored in the storage capacitor.

[0017] Alternatively, in the solid-state imaging device, in each of the plurality of first pixels, The potential barrier between the two or more photoelectric conversion elements may be higher than the potential barrier between the photoelectric conversion element and the storage capacitor.

[0018] In this case, preferably, in each of the plurality of second pixels, When the charges stored in the one or more photoelectric conversion elements are equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges stored in the one or more photoelectric conversion elements; When the charge accumulated in any of the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charge accumulated in the one or more photoelectric conversion elements and the charge accumulated in the storage capacitor.

[0019] Moreover, the solid-state imaging device, for each of the plurality of first pixels, It is possible to determine whether the charges held in each of the two or more photoelectric conversion elements have reached a threshold value indicating that an overflow has occurred in the photoelectric conversion element, and if none of the charges have reached the threshold value, output a phase difference data signal generated based on the charges generated in the two or more photoelectric conversion elements in the first pixel, and if at least one of the charges has reached the threshold value, output a phase difference data signal generated based on the charges generated in the second set of pixels determined by the solid-state imaging device.

[0020] The camera device according to the present invention comprises: The solid-state imaging device includes a control device configured to control the solid-state imaging device.

[0021] The camera equipment is configured, for example, based on a signal from the control device, to determine whether the solid-state imaging device outputs a phase difference data signal for each pixel based on the charge generated in the two or more photoelectric conversion elements that the first pixel has, and / or whether it outputs a phase difference data signal for each pixel based on the charge generated in the set of two or more second pixels.

[0022] The camera device may be, for example, a mobile terminal. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing the configuration of a solid-state imaging device according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of an arrangement of pixels arranged in a pixel array section, and a number of specific examples of the second pixel are shown together in one diagram. [Diagram 3] FIG. 3 is a cross-sectional view showing the structure of the first pixel. [Figure 4] FIG. 4 is a cross-sectional view showing the structure of the second pixel. [Diagram 5] FIG. 5 is an equivalent circuit diagram of a pixel included in the solid-state imaging device. [Figure 6] FIG. 6 is a diagram showing a potential barrier between a photoelectric conversion element and a storage capacitor in each pixel according to the first embodiment. [Figure 7] FIG. 7 is a timing chart of the pixel. [Figure 8] FIG. 8 is a flowchart showing a first output example of the phase difference data signal. [Figure 9] FIG. 9 is a flowchart showing a second output example of the phase difference data signal. [Figure 10] FIG. 10 is a flowchart showing a third output example of the phase difference data signal. [Figure 11] FIG. 11 is a flowchart showing in detail step 1002 of the third output example in the first embodiment. [Figure 12] FIG. 12 is a diagram showing a potential barrier between a photoelectric conversion element and a storage capacitor in each pixel according to the second embodiment. [Figure 13] FIG. 13 is a flowchart showing in detail step 1002 of the third output example in the second embodiment. [Figure 14] FIG. 14 is a diagram showing the configuration of a solid-state imaging device according to another embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing the structure of a solid-state imaging device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The solid-state imaging device according to the present invention comprises: A solid-state imaging device including a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels, Each of the first pixels and the second pixels is One or more photoelectric conversion elements that configure the light receiving surface of the pixel and generate electric charges by photoelectrically converting received light; a floating diffusion connected to the one or more photoelectric conversion elements and converting the electric charge into a voltage corresponding to the amount of the electric charge; an overflow storage capacitor connected to the floating diffusion and capable of storing the charge overflowing from the one or more photoelectric conversion elements; Equipped with Each of the plurality of first pixels includes two or more of the photoelectric conversion elements, the floating diffusion is connected to all of the two or more photoelectric conversion elements, and is configured to generate a phase difference data signal by comparing the charges accumulated in the two or more photoelectric conversion elements, Two or more second pixels among the plurality of second pixels together constitute a set of second pixels; The second set of pixels is configured such that a phase difference data signal can be generated by comparing the charges stored in each of the second pixels constituting the second set of pixels.

[0025] According to this configuration, by appropriately using two methods, namely, a method based on charges generated in a plurality of photoelectric conversion elements of a first pixel provided in the solid-state imaging device, and a method based on charges generated in a set of second pixels provided in the solid-state imaging device, a phase difference data signal can be generated with high accuracy for both high-brightness subjects and low-brightness subjects.

[0026] For example, when the subject has high brightness and generates charges exceeding the storage capacity that the photoelectric conversion element included in the pixel can hold, a method based on charges generated in a plurality of photoelectric conversion elements, such as the above-mentioned dual pixel method, may not be able to generate an accurate phase difference data signal because the charges overflow from the photoelectric conversion elements. On the other hand, in a method that compares charges generated in a plurality of pixel sets, such as the second pixel set, if the charges generated in each of the plurality of pixels are equal to or less than the total amount that can be stored by the photoelectric conversion element and the additional storage capacitance, an accurate phase difference data signal can be provided by comparing the charges held in each pixel of the plurality of pixel sets. Furthermore, since the electric charges overflowing from the photoelectric conversion element are stored in the additional storage capacitor, a captured image with a high dynamic range can be generated by reading out the electric charges.

[0027] Alternatively, if the subject has low brightness, the charge generated in the photoelectric conversion element contained in the pixel does not exceed the storage capacity that can be held, and charge overflow does not occur, a more accurate phase difference data signal based on a dual (or triple, quad, etc.) pixel method can be provided based on the phase difference data signals generated in all of the photoelectric conversion elements in the first pixel.

[0028] In the solid-state imaging device, for example, in each of the two or more pixels constituting the second pixel set, a part of the light receiving surface of the pixel is masked so as to prevent light reception on the part of the light receiving surface.

[0029] Alternatively, in the solid-state imaging device, each of the plurality of first pixels is independently provided with one on-chip lens (OCL); Each of the second pixel sets is provided with an independent on-chip lens (OCL), and the two or more pixels constituting the second pixel set share the one on-chip lens (OCL).

[0030] In the solid-state imaging device, in each of the plurality of first pixels, The potential barrier between the two or more photoelectric conversion elements is lower than the potential barrier between the photoelectric conversion element and the storage capacitor.

[0031] According to this configuration, when an electric charge exceeding the storage capacity that can be held is generated in one of the two or more photoelectric conversion elements included in the first pixel, the electric charge overflowing from the photoelectric conversion element will preferentially flow into another photoelectric conversion element included in the pixel, rather than into the additional storage capacity. Typically, the electric charge held in the photoelectric conversion element tends to have less noise than the electric charge held in the additional storage capacity, so that the signal-to-noise ratio of the captured image obtained can be increased.

[0032] In this case, preferably, in each of the plurality of second pixels, When the sum of the charges accumulated in the one or more photoelectric conversion elements is equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges accumulated in the one or more photoelectric conversion elements; When the sum of the charges stored in the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges stored in the one or more photoelectric conversion elements and the charges stored in the storage capacitor.

[0033] According to this configuration, when the total charge stored in the photoelectric conversion element of the second pixel is equal to or less than a predetermined saturation charge amount (for example, when it is estimated that the charge overflowing from the photoelectric conversion element is not flowing into the additional storage capacitance), a phase difference data signal is generated without taking the additional storage capacitance into consideration, so that a phase difference data signal with higher accuracy can be generated that is not affected by noise caused by the storage capacitance.

[0034] Alternatively, in the solid-state imaging device, in each of the plurality of first pixels, The potential barrier between the two or more photoelectric conversion elements may be higher than the potential barrier between the photoelectric conversion element and the storage capacitor.

[0035] According to this configuration, when a charge that exceeds the storage capacity is generated in one of the two or more photoelectric conversion elements included in the first pixel, the charge that overflows from the photoelectric conversion element flows preferentially into the additional storage capacitor. In this case, even if a charge overflow occurs in the photoelectric conversion element of the pixel, as long as there is only one photoelectric conversion element that has overflowed, the charge held in the additional storage capacitor can be regarded as the charge generated by the overflowed photoelectric conversion element. Therefore, the first pixel can generate a highly reliable phase difference data signal even for a relatively bright subject.

[0036] In this case, preferably, in each of the plurality of second pixels, When the charges stored in the one or more photoelectric conversion elements are equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charges stored in the one or more photoelectric conversion elements; When the charge accumulated in any of the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the sum of the charge accumulated in the one or more photoelectric conversion elements and the charge accumulated in the storage capacitor.

[0037] According to this configuration, when the charges stored in the photoelectric conversion elements of the second pixel are all below a predetermined saturation charge amount (for example, when it is estimated that the charges overflowing from the photoelectric conversion elements are not flowing into the additional storage capacitance), a phase difference data signal is generated without taking the additional storage capacitance into consideration, so that a phase difference data signal with higher accuracy can be generated that is not affected by noise caused by the storage capacitance.

[0038] Moreover, the solid-state imaging device performs the following for each of the plurality of first pixels: It is possible to determine whether the charges held in each of the two or more photoelectric conversion elements have reached a threshold value indicating that an overflow has occurred in the photoelectric conversion element, and if none of the charges have reached the threshold value, output a phase difference data signal generated based on the charges generated in the two or more photoelectric conversion elements in the first pixel, and if at least one of the charges has reached the threshold value, output a phase difference data signal generated based on the charges generated in the second set of pixels determined by the solid-state imaging device.

[0039] According to this configuration, by determining whether the phase difference information is retained without being destroyed for each of the first pixels (for example, whether charge generated in a photoelectric conversion element has overflowed and flowed into another photoelectric conversion element), the solid-state imaging device can adaptively determine for each pixel which of the two phase difference data signal generation methods described above is to be adopted in order to output a more accurate phase difference data signal.

[0040] In this case, if it is determined that the phase difference information in a certain first pixel is destroyed and an accurate phase difference data signal cannot be generated by a method of comparing charges generated in multiple photoelectric conversion elements of the first pixel, the solid-state imaging device, for example, selects charge information of a nearby second pixel from the charge information of multiple pixels currently loaded into the line memory, and regards the phase difference data signal generated based on the charge information of the nearby second pixel as the phase difference data signal generated from the first pixel.

[0041] The camera device according to the present invention comprises: The solid-state imaging device includes a control device configured to control the solid-state imaging device.

[0042] According to this configuration, the camera equipment can generate a phase difference data signal with high accuracy for both high-brightness and low-brightness subjects by appropriately using two methods: a method of comparing charges generated in two or more photoelectric conversion elements in a first pixel of the solid-state imaging device, and a method of comparing charges generated in a set of second pixels in the solid-state imaging device.

[0043] The camera equipment is configured, for example, based on a signal from the control device, to determine whether the solid-state imaging device outputs a phase difference data signal for each pixel based on the charge generated in the two or more photoelectric conversion elements that the first pixel has, and / or whether it outputs a phase difference data signal for each pixel based on the charge generated in the set of two or more second pixels.

[0044] According to this configuration, the solid-state imaging device can control from outside the solid-state imaging device which method (or both methods) to use to output a phase difference data signal, between a method of comparing charges generated in two or more photoelectric conversion elements of a first pixel and a method of comparing charges generated in a set of second pixels, by a control device of the camera equipment.

[0045] The camera device may be, for example, a mobile terminal such as a smart phone, a mobile phone, a tablet computer, a personal digital assistant (PDA), or the like.

[0046] First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

[0047] [Example of the configuration of a solid-state imaging device] The solid-state imaging device of this embodiment is incorporated in a camera device such as a smartphone or a digital camera, and includes a CMOS image sensor.

[0048] 1, the solid-state imaging device 1 includes a pixel array section 2, a vertical drive section 3, a plurality of column signal processing sections 4, a horizontal drive section 5, a control section 6, and a signal processing section 7. The solid-state imaging device 1 also includes a memory 8 capable of storing signals and the like processed by the signal processing section 7. In the solid-state imaging device 1 of this embodiment, at least the pixel array section 2, the vertical drive section 3, the plurality of column signal processing sections 4, the horizontal drive section 5, and the control section 6 configure a CMOS image sensor.

[0049] At least the pixel array section 2, the vertical drive section 3, the column signal processing section 4, the horizontal drive section 5, the control section 6, and the signal processing section 7 are arranged on the same semiconductor substrate or on multiple semiconductor substrates electrically connected to each other. The signal processing section 7 and the memory 8 may be arranged on the semiconductor substrate on which the pixel array section 2, the vertical drive section 3, the column signal processing section 4, the horizontal drive section 5, and the control section 6 are arranged, or may be arranged on a different substrate. In other words, the locations where the signal processing section 7 and the memory 8 are arranged are not limited.

[0050] The pixel array unit 2 has a plurality of pixels 10 arranged two-dimensionally in a matrix. Each of the plurality of pixels 10 has two photoelectric conversion elements 11R and 11L that form a light receiving surface of the pixel 10, photoelectrically convert input light (incident light) to an electric charge (electric charge) in an amount corresponding to the amount of input light, and output the accumulated signal charge.

[0051] The pixels 10 are composed of a plurality of first pixels 10A whose light receiving surfaces are not shielded from light by an opaque film, and second pixels 10B whose light receiving surfaces are partially shielded from light by an opaque film, but the arrangement of the first and second pixels 10A and 10B and the light shielding state of the light receiving surfaces are not shown in Fig. 1. The specific configuration of each pixel 10, including the arrangement and the light shielding state of the light receiving surfaces, will be described later in detail.

[0052] In addition to these first and second pixels 10A, 10B, the pixel array section 2 may also include dummy unit pixels having a structure without a photoelectric conversion element, and pixels whose light receiving surfaces are shielded from external light input.

[0053] The pixel array unit 2 has a plurality of row signal lines 21 arranged for each row and extending in the row direction for the matrix-like pixel arrangement, and a plurality of column signal lines 22 arranged for each column and extending in the column direction. Each of the row signal lines 21 is connected to the vertical drive unit 3, and each of the column signal lines 22 is connected to a corresponding column signal processor 4.

[0054] The vertical driving unit 3 is configured, for example, by a shift register, selects a predetermined row signal line 21, and supplies a pulse (signal) for driving the pixels 10 to the selected row signal line 21, thereby driving the pixels 10 on a row-by-row basis. In detail, the vertical driving unit 3 sequentially selects and scans each pixel 10 of the pixel array unit 2 on a row-by-row basis in the vertical direction, and supplies a pixel signal based on a signal charge generated in the photoelectric conversion element 11 of each pixel 10 according to the amount of input light to the column signal processing unit 4 through the column signal line 22.

[0055] Each of the multiple column signal processing units 4 is arranged for each column of pixels 10, and performs signal processing such as noise removal for each pixel column on pixel signals output from one row of pixels 10. Each column signal processing unit 4 of this embodiment performs signal processing such as correlated double sampling (CDS) for removing pixel-specific fixed pattern noise and A / D (Analog / Digital) conversion.

[0056] The horizontal drive unit 5 is composed of, for example, a shift register, and sequentially outputs horizontal scanning pulses to select each of the multiple column signal processing units 4 in turn, and output the pixel signals processed by each column signal processing unit 4 to the signal processing unit 7 in turn.

[0057] The control unit 6 controls the operation of each unit of the solid-state imaging device 1. Specifically, the control unit 6 receives an input clock signal and data instructing an operation mode and the like, and outputs data such as internal information of the solid-state imaging device 1. In more detail, the control unit 6 generates clock signals and control signals that serve as a reference for the operation of the vertical drive unit 3, the column signal processing unit 4, the horizontal drive unit 5, and the like, based on a vertical synchronization signal, a horizontal synchronization signal, and a master clock signal, and outputs the generated clock signals and control signals to the vertical drive unit 3, the column signal processing unit 4, the horizontal drive unit 5, and the like.

[0058] The signal processing unit 7 performs various signal processing such as arithmetic processing on the pixel signals output from each column signal processing unit 4. The signal processing unit 7 in this embodiment is a DSP (Digital Signal Processor).

[0059] There is no specific limitation on the location of the signal processing unit 7. In the solid-state imaging device 1 of the present embodiment, the signal processing unit 7 is disposed at a position different from the CMOS image sensor, but the entire configuration of the signal processing unit 7 may be disposed (mounted) in the CMOS image sensor, or a part of the configuration of the signal processing unit 7 may be disposed in the CMOS image sensor.

[0060] The memory 8 is a line memory, a frame memory, a FIFO, or the like, and can store pixel signals output from each column signal processor 4, and the like.

[0061] [Example of pixel arrangement in pixel array] Next, a specific example of the arrangement of pixels arranged in a matrix in the pixel array section 2 will be described with reference to FIG.

[0062] As shown in Fig. 2, a plurality of pixels 10 are two-dimensionally arranged in a matrix in the pixel array section 2. In the example shown in Fig. 2, the pixels 10 are arranged in 4 rows and 9 columns. Furthermore, each pixel 10 is provided with two photoelectric conversion elements 11R and 11L.

[0063] 2, the pixels 10 are composed of a plurality of first pixels 10A whose light receiving surfaces are not shielded from light by the opaque film 60, and second pixels 10B whose light receiving surfaces are partially shielded from light by the opaque film 60. In the example shown in FIG. 2, when the pixel in the mth row and nth column is represented as pixel (m,n), the pixels arranged at (1,1), (1,5), (1,9), (3,1), (3,5), (3,9), (5,5), and (5,9) are second pixels 10B whose light receiving surfaces are partially shielded from light by the opaque film 60, and the remaining pixels are first pixels 10A.

[0064] The first pixel 10A generates an imaging data signal based on the signal charge accumulated in the pixel, and when the signal charge generated in the two photoelectric conversion elements 11R, 11L included in the pixel does not overflow, it can generate a phase difference data signal of the received light by comparing the amounts of signal charge generated in the two photoelectric conversion elements 11R, 11L.

[0065] On the other hand, when the signal charges generated in the photoelectric conversion elements 11R, 11L of the first pixel 10A overflow and therefore a phase difference data signal cannot be generated from the first pixel 10A, the second pixel 10B is configured to be able to generate a phase difference data signal of the received light by comparing the charges accumulated in each of the second pixels 10B constituting a set of two or more corresponding second pixels 10B.

[0066] In this embodiment, the two or more corresponding pixels constituting the set of the second pixels 10B refer to two or more pixels whose receivable light phases are complementary to each other, such that light whose phase is blocked and cannot be received by one second pixel 10B can be received without being blocked by another second pixel 10B. In the example shown in Fig. 2, when the row direction in Fig. 2 is left and right and the column direction is up and down, the combination of pixels (1,1) and (3,1) whose upper and lower halves are respectively blocked, the combination of pixels (1,5) and (1,9) whose right and left halves are respectively blocked, the combination of pixels (3,9) and (5,9) whose right and left halves are respectively blocked, and the combination of pixels (3,5) and (5,5) whose upper and lower half are respectively blocked correspond to two corresponding pixels.

[0067] 2 illustrates combinations of pixels in which the upper and lower halves, the right and left halves, and the upper right and lower left halves are shielded from light, for the sake of convenience, but this figure illustrates a number of specific examples in one drawing, and it is not necessary for all of these combinations of second pixels 10B to be arranged in the pixel array section 2. For example, the second pixels 10B arranged in the pixel array section 2 may all be pixels in which the right or left half is shielded from light.

[0068] Here, in order to ensure sufficient accuracy of the phase difference data signal generated by the set of second pixels 10B, it is preferable that two or more corresponding pixels constituting the set of second pixels 10B are arranged in rows and columns that are somewhat close to each other. Although not limited to the following, for example, these pixels can be designed so that they are not separated from each other by more than 20 pixels in either row or column in the two-dimensional arrangement of the pixel array unit 2. However, unlike the first pixel 10A, the second pixel 10B does not usually contribute to the generation of an image data signal, so the image data signal at the location where the second pixel 10B is arranged may need to be complemented by the image data signal from the nearby first pixel 10A. In this case, if the second pixels 10B are arranged too close to each other, there is a possibility that the complementation of the image data signal may be hindered. Therefore, although not limited to the following, two or more corresponding pixels constituting the set of the second pixel 10B may be designed to be separated from each other by one pixel or more in both rows and columns in the two-dimensional array of the pixel array unit 2, for example.

[0069] The ratio between the number of first pixels and the number of second pixels constituting the pixel 10 arranged in the pixel array section 2 is not particularly limited, but in order to be able to obtain a good imaging data signal based on the signal charge accumulated in the first pixel 10A while obtaining a phase difference data signal with sufficient accuracy using the second pixel even in a high brightness state in which signal charge overflows from at least one of the two photoelectric conversion elements 11R, 11L included in the first pixel 10A, the ratio may be, for example, in the range of number of first pixels:number of second pixels=4:1 to 64:1, preferably in the range of 6:1 to 32:1, more preferably in the range of 8:1 to 24:1, and may be, for example, 12:1.

[0070] [Pixel configuration] Next, a specific structure of the pixels 10 arranged in a matrix in the pixel array section 2 will be described with reference to FIGS.

[0071] First, with reference to FIG. 3, a schematic structure of a first pixel 10A whose light receiving surface is not shielded from light by an opaque film will be described.

[0072] As shown in FIG. 3, the first pixel 10A includes a semiconductor region 20 that constitutes a light receiving surface and includes two photoelectric conversion elements 11R, 11L that generate signal charges by photoelectrically converting received light, and an independent on-chip lens 30 that is provided on the semiconductor region 20 so as to cover both of the two photoelectric conversion elements 11R, 11L.

[0073] With this configuration, light (for example, L1 and L2 shown in FIG. 3) entering the first pixel 10A passes through different optical paths while being refracted by the on-chip lens 30, enters one of the two photoelectric conversion elements 11R and 11L, and is received. That is, the light entering the first pixel 10A is received by either of the two photoelectric conversion elements 11R and 11L depending on the phase of the light, so that a phase difference occurs between the light received by the two photoelectric conversion elements 11R and 11L. Therefore, in the first pixel 10A, a phase difference data signal can be generated by comparing the amounts of light received by the two photoelectric conversion elements 11R and 11L, that is, by comparing the amounts of signal charges generated by photoelectric conversion of the light.

[0074] In this embodiment, the first pixel 10A further includes a color filter 40 and a transparent film 50 between the semiconductor region 20 and the on-chip lens 30. For example, R (red), G (green) or B (blue) color filters 40 are selected for each pixel so that each pixel has a desired arrangement (for example, a Bayer arrangement) in the planar arrangement of the pixel array section 2 as shown in Fig. 2. Note that the color filter 40 and the transparent film 50 are not essential components and may be omitted.

[0075] Next, with reference to FIG. 4, a schematic structure of a second pixel 10B whose light receiving surface is partially shielded from light by an opaque film will be described.

[0076] Similar to the first pixel A, the second pixel 10B includes a semiconductor region 20 including two photoelectric conversion elements 11R and 11L, an on-chip lens 30, a color filter 40, and a transparent film 50. However, unlike the first pixel 10A, the second pixel 10B has a light receiving surface that is partially shielded (masked) by an opaque film 60.

[0077] Due to this configuration, the second pixel 10B cannot receive light of a phase blocked by the opaque film 60, and receives only light of a specific phase that is not blocked. Therefore, unlike the first pixel 10A, the second pixel 10B cannot generate a phase difference data signal by itself, but a phase difference data signal can be generated by comparing the amount of light received by each of the second pixels 10B in a combination of second pixels 10B in adjacent rows and columns in which the phases of light received are complementary, that is, by comparing the amount of signal charge generated by photoelectric conversion of the light.

[0078] To explain this in detail based on the example shown in FIG. 4, the left side of FIG. 3 shows a second pixel 10B_R in which the left side of the light receiving surface (in this example, the photoelectric conversion element 11L) is shielded by an opaque film 60 as an example of the second pixel 10B, and the right side of FIG. 4 shows a second pixel 10B_L in which the right side of the light receiving surface (in this example, the photoelectric conversion element 11R) is shielded by an opaque film 60. The second pixel 10B_R does not receive light of the phase on the left side that is shielded, and only light of the phase on the right side is received, while the second pixel 10B_L does not receive light of the phase on the right side that is shielded, and only light of the phase on the left side is received. Therefore, the second pixel 10B_R that receives only light of the phase on the right side and the second pixel 10B_L that receives only light of the phase on the left side are in a complementary relationship with each other, and a phase difference data signal can be generated by comparing the amounts of light received at these pixels.

[0079] In the second pixels 10B_R and 10B_L shown in Fig. 4, one of the photoelectric conversion elements 11R, 11L is completely shielded by the opaque film 60, but the second pixel 10B may have each of the photoelectric conversion elements 11R, 11L partially shielded, as in some of the second pixels 10B shown in Fig. 2. For example, as in the second pixels 10B arranged at (1,1) and (3,1) in the pixel array section 2 shown in Fig. 2, a combination of the second pixels 10B in a mutually complementary relationship may be formed by a pair of a pixel in which the upper half of each of the photoelectric conversion elements 11R, 11L constituting the light receiving surface is shielded, and a pixel in which the lower half of each of the photoelectric conversion elements 11R, 11L is shielded.

[0080] In addition, in this embodiment, the second pixel 10B includes two photoelectric conversion elements, similar to the first pixel 10A, but the second pixel 10B may include only one photoelectric conversion element.

[0081] Next, with reference to FIG. 5, a circuit configuration included in the semiconductor region 20 and common to the first pixel 10A and the second pixel 10B constituting the pixel 10 will be described.

[0082] 5, the pixel 10 includes two photoelectric conversion elements 11R and 11L that generate signal charges by photoelectric conversion in response to input light, a floating diffusion 12 that converts the signal charges generated in the photoelectric conversion elements 11R and 11L into a voltage signal (voltage) corresponding to the amount of the signal charges, and a storage capacitance (overflow storage capacitance) 13 that is connected to the floating diffusion 12 and can store signal charges that overflow from the photoelectric conversion elements 11R and 11L. The photoelectric conversion elements 11R and 11L in this embodiment are, for example, photodiodes.

[0083] The pixel 10 also includes transfer transistors (first switch transistors) 14R, 14L that connect the photoelectric conversion elements 11R, 11L, respectively, to the floating diffusion 12, a retention switch transistor (second switch transistor) 15 that connects the floating diffusion 12 to the retention capacitance 13, a reset transistor (third switch transistor) 16 that connects the retention capacitance 13 to a reset power supply (reset potential) VDD1, an amplification transistor 17 that amplifies the voltage signal of the floating diffusion 12, and a selection transistor 18 that connects the amplification transistor 17 to a column signal line 22.

[0084] A plurality of row signal lines 21 are wired for each pixel row to the plurality of pixels 10 arranged in a matrix. Various drive signals φTX_L, φTX_R, φS, φRES, and φSEL are supplied from the vertical drive unit 3 to each pixel 10 via the row signal lines 21. These drive signals φTX_L, φTX_R, φS, φRES, and φSEL are the pulses described above.

[0085] The floating diffusion 12 converts the signal charges generated in the photoelectric conversion elements 11R and 11L into a voltage signal and outputs the voltage signal. The floating diffusion 12 of this embodiment is also connected to a reset power supply VDD1 via a retention switch transistor 15 and a reset transistor 16 in this order.

[0086] The retention capacitance 13 is a capacitor, and is connected to the floating diffusion 12 via the retention switch transistor 15 as described above, and is also connected to the reset power supply VDD1 via the reset transistor 16.

[0087] A driving signal φTX_L is applied to the gate electrode of the transfer transistor 14L. This driving signal φTX_L is output from the vertical driving unit 3 based on a signal (command) from the control unit 6. When the driving signal φTX_L becomes Hi (i.e., the transfer transistor 14L is turned on), the transfer gate of the transfer transistor 14L becomes conductive, and the signal charge accumulated in the photoelectric conversion element 11 is transferred to the floating diffusion 12 via the transfer transistor 14L. When the driving signal φTX_L becomes Low, the transfer transistor 14L is turned off.

[0088] Similarly, a drive signal φTX_R is applied to the gate electrode of the transfer transistor 14R. This drive signal φTX_R is output from the vertical drive unit 3 based on a signal (command) from the control unit 6. When the drive signal φTX_R becomes Hi (i.e., the transfer transistor 14R is turned on), the transfer gate of the transfer transistor 14R becomes conductive, and the signal charge accumulated in the photoelectric conversion element 11R is transferred to the floating diffusion 12 via the transfer transistor 14R. When the drive signal φTX_R becomes Low, the transfer transistor 14R is turned off.

[0089] A drive signal φS is applied to the gate electrode of the hold switch transistor 15. This drive signal φS is output from the vertical drive unit 3 based on a signal from the control unit 6. When the drive signal φS becomes Hi (i.e., the hold switch transistor 15 turns on), the hold gate of the hold switch transistor 15 becomes conductive, allowing signal charge to move from the floating diffusion 12 to the hold capacitance 13. When the drive signal φS becomes Low, the hold switch transistor 15 turns off.

[0090] A drive signal φRES is applied to the gate electrode of the reset transistor 16. This drive signal φRES is output from the vertical drive unit 3 based on a signal from the control unit 6. When the drive signal φRES becomes Hi (i.e., the reset transistor 16 is turned on), the reset gate of the reset transistor 16 becomes conductive, and the potentials of the floating diffusion 12 and the holding capacitance 13, or the potential of the holding capacitance 13, are reset to the level (reset level) of the reset power supply (reset potential) VDD1 in accordance with the drive signal φS applied to the gate electrode of the holding switch transistor 15. When the drive signal φRES becomes Low, the reset transistor 16 is turned off.

[0091] The amplifier transistor 17 has a gate electrode connected to the floating diffusion 12 and a drain electrode connected to a power supply VDD2. The amplifier transistor 17 serves as an input section of a readout circuit (so-called source follower circuit SF) that reads out the voltage of the floating diffusion 12 as a pixel signal. That is, the amplifier transistor 17 has a source electrode connected to a column signal line 22 via a selection transistor 18, and thereby constitutes a constant current source connected to one end of the column signal line 22 and a source follower circuit SF.

[0092] The selection transistor 18 is connected to the source electrode of the amplification transistor 17 and the column signal line 22. A drive signal φSEL is applied to the gate electrode of the selection transistor 18. This drive signal φSEL is output from the vertical drive unit 3 based on a signal from the control unit 6. When the drive signal φSEL becomes Hi (i.e., the selection transistor 18 is turned on), the selection gate of the selection transistor 18 becomes conductive and the pixel 10 becomes selected. As a result, the pixel signal output from the amplification transistor 17 is output to the column signal line 22 via the selection transistor 18. When the drive signal φSEL becomes Low, the selection transistor 18 is turned off.

[0093] Finally, with reference to FIG. 6, the relationship between the potential barrier between the two photoelectric conversion elements 11R and 11L in the pixel 10 and the potential barrier between the two photoelectric conversion elements 11R and 11L and the storage capacitor 13 will be described.

[0094] 6, in the pixel 10 of the present embodiment, the potential barrier between the two photoelectric conversion elements 11R, 11L is lower than the potential barrier between the two photoelectric conversion elements 11R, 11L and the holding capacitance 13. In the circuit configuration shown in Fig. 5, the potential barrier between the two photoelectric conversion elements 11R, 11L is set by adjusting the holding gates of the transfer transistors 14R, 14L, and the potential barrier between the two photoelectric conversion elements 11R, 11L and the holding capacitance 13 is set by adjusting the holding gate of the holding switch transistor 15.

[0095] Therefore, in the pixel 10 of this embodiment, when the transfer transistors 14R, 14L and the hold switch transistor 15 are off and a signal charge is generated in one of the photoelectric conversion elements 11R, 11L (e.g., photoelectric conversion element 11L) that exceeds the storage capacity that can be held, the signal charge overflowing from the one photoelectric conversion element 11R, 11L will first overcome the relatively low potential barrier (the hold gates of the transfer transistors 14R, 14L) between the photoelectric conversion elements 11R, 11L and then flow preferentially into the other photoelectric conversion element 11R, 11L (e.g., photoelectric conversion element 11R) and be accumulated there. Only when the signal charges accumulated in both photoelectric conversion elements 11R, 11L reach the limit of the storage capacity that can be held, does the signal charge overflow from photoelectric conversion elements 11R, 11L overcome the relatively high potential barrier (the hold gate of hold switch transistor 15) between photoelectric conversion elements 11R, 11L and hold capacitance 13 and flow into and be stored in hold capacitance 13.

[0096] Typically, the charges held in the photoelectric conversion elements 11R, 11L tend to have lower noise than the signal charges held in the holding capacitance 13. Therefore, according to the pixel 10 configured to store the signal charges generated in the photoelectric conversion elements 11R, 11L in the photoelectric conversion elements 11R, 11L as much as possible, instead of in the holding capacitance 13, as in the present embodiment, an effect is achieved in that the signal-to-noise ratio of the output shooting data signal is relatively high.

[0097] In addition, in the first pixel 10A, when the signal charge overflowing from one of the photoelectric conversion elements 11R, 11L flows into the other photoelectric conversion element 11R, 11L, the information of the light of the phase received by each of the photoelectric conversion elements 11R, 11L overflows or is mixed, so the signal charge held in the photoelectric conversion elements 11R, 11L becomes useless for generating a correct phase difference data signal. Therefore, in this embodiment, when the signal charge overflows in a certain first pixel 10A, the first pixel 10A can output a reliable imaging data signal by a driving method described later, but cannot output a reliable phase difference data signal. In such a case, the signal generated by the second pixel 10B is utilized as a reliable phase difference data signal.

[0098] [Example of driving pixels in a solid-state imaging device] The drive timing of the pixel 10 configured as above will be described with reference to Fig. 7. Fig. 7 shows the drive signal (control signal pulse) of the pixel 10 and the output voltage (pixel signal) appearing in the column signal line 22 in response to the drive signal, where Vout denotes the output voltage.

[0099] First, at time t01, while the selection transistor 18 is off, the transfer transistors 14R and 14L, the hold switch transistor 15, and the reset transistor 16 are turned on, and the floating diffusion 12 and the hold capacitance 13 are at the reset level.

[0100] In this way, when the transfer transistor 14 is turned off while the floating diffusion 12 is connected to the reset power supply VDD1, the photoelectric conversion elements 11R, 11L enter a floating state, and accumulation of signal charge generated by light entering each of the photoelectric conversion elements 11R, 11L begins.

[0101] Almost simultaneously (more specifically, with a slight delay) when the transfer transistors 14R and 14L are turned off, the hold switch transistor 15 and the reset transistor 16 are turned off, so that the floating diffusion 12 and the hold capacitance 13 also go into a floating state.

[0102] Here, when signal charges overflow (overflow) from at least one of the photoelectric conversion elements 11R, 11L, the holding capacitance 13, which is in a floating state, and the photoelectric conversion element 11R, 11L that has not yet overflowed can hold (store) the overflowed signal charges. In detail, as described above with reference to Fig. 6, the signal charges overflowing from one of the photoelectric conversion elements 11R, 11L are first held (stored) in the other photoelectric conversion element 11R, 11L. After that, when the signal charges held in both the photoelectric conversion elements 11R, 11L reach the limit of the storage capacity that can be held, the overflowed signal charges flow into the holding capacitance 13 and are held therein.

[0103] With the transfer transistors 14R, 14L, the hold switch transistor 15, and the reset transistor 16 turned off in this manner, readout of the pixel signal from the pixel 10 begins at time t02, a predetermined accumulation period ΔT after the transfer transistors 14R, 14L are turned off.

[0104] Specifically, when each of the switch transistors 14R, 14L, 15, 16, and 18 of the pixel 10 is in an off state, the control unit 6 (more specifically, the vertical drive unit 3 that receives an instruction from the control unit 6) sets the drive signal φSEL to Hi to turn on the selection transistor 18, and the pixel 10 is connected to the column signal line 22.

[0105] Next, at time t03, the potential of the floating diffusion 12 (floating diffusion reference potential) is read out from the source follower circuit SF, A / D converted, and then stored in the memory 8 as a first signal (pixel signal).

[0106] In the solid-state imaging device 1 of this embodiment, the first signal is stored in the memory 8 after being A / D converted in the column signal processing unit 4 (i.e., converted into a digital signal), but is not limited to this configuration. The pixel signal (the voltage of the floating diffusion 12) read out from the source follower circuit SF may be subjected to each of the subsequent processes while remaining an analog signal. The same applies to the pixel signals (second to fifth signals) read out from the source follower circuit SF at a later timing.

[0107] Next, at time t04, the control unit 6 sets the drive signal φTX_R to Hi to turn on the transfer transistor 14R, and after the photoelectric conversion element 11R transfers the signal charge accumulated during the accumulation period ΔT to the floating diffusion 12, it sets the drive signal φTX_R to Low to turn off the transfer transistor 14.

[0108] This signal is read out from the source follower circuit SF at time t05, A / D converted, and then stored in the memory 8 as a second signal (pixel signal).

[0109] Next, at time t06, the control unit 6 sets both of the drive signals φTX_R and φTX_L to Hi to turn on the transfer transistors 14R and 14L, and the photoelectric conversion elements 11R and 11L transfer the signal charge accumulated during the accumulation period ΔT to the floating diffusion 12, and then sets the drive signals φTX_R and φTX_L to Low to turn off the transfer transistors 14.

[0110] This signal is read out from the source follower circuit SF at time t07, A / D converted, and then stored in the memory 8 as a third signal (pixel signal).

[0111] Next, at time t08, the control unit 6 sets the drive signal φS to Hi to turn on the hold switch transistor 15, thereby conducting the floating diffusion 12 and the hold capacitance 13, and then sets the drive signals φTX_R and φTX_L to Hi and Low again to turn on and off the transfer transistor 14. The voltage of the floating diffusion 12 at this time is read out from the source follower circuit SF at t09, A / D converted, and then stored in the memory 8 as a fourth signal (pixel signal).

[0112] Finally, at time t10, the control unit 6 sets the drive signal φRES to Hi to turn on the reset transistor 16, thereby connecting the floating diffusion 12 and the holding capacitance 13 to a reset power supply (reset potential) VDD1 and initializing (resetting) all the signal charges in the floating diffusion 12 and the holding capacitance 13. The initialized voltages (reset levels) of the floating diffusion 12 and the holding capacitance 13 are read out from the source follower circuit SF at t11, A / D converted, and then stored in the memory 8 as a fifth signal (pixel signal).

[0113] By processing the first to fifth signals acquired in driving the pixel 10 as described above, it is possible to restore a signal based on the signal charges held in the photoelectric conversion elements 11R and 11L and the storage capacitor 13. Specifically, by subtracting the first signal from the second signal, a signal (signal R) based on the charges held in the photoelectric conversion element 11R, in which the reset noise and the deviation of the DC level have been corrected, is restored. Similarly, by subtracting the first signal from the third signal, a signal (signal R+L) based on the sum of the charges held in the photoelectric conversion elements 11R and 11L, in which the reset noise and the deviation of the DC level have been corrected, is restored. Furthermore, by subtracting the second signal from the third signal, a signal (signal L) based on the sum of the charges held in the photoelectric conversion element 11L, in which the reset noise and the deviation of the DC level have been corrected, is restored. Furthermore, by subtracting the signal 05 from the signal 04, a signal (signal R+L+C) based on the signal charges held in the photoelectric conversion elements 11R and 11L and the storage capacitor 13, in which the deviation of the DC level has been corrected, is restored.

[0114] Here, when the pixel 10 is the first pixel 10A, if the signal charge generated by the light entering each of the photoelectric conversion elements 11R, 11L during the accumulation period ΔT does not exceed the capacity that the photoelectric conversion elements 11R, 11L can hold, and if no overflow occurs from the photoelectric conversion elements 11R, 11L, then the signal R+L restored by the above processing can be used as a correct image data signal.

[0115] In addition, in this case, the information output from the photoelectric conversion elements 11R, 11L each holds information regarding the phase of the incoming light, so the signals R and L restored by the above processing can be used as reliable phase signals from which a correct phase difference data signal can be generated by comparing them.

[0116] Furthermore, in the first pixel 10A, if the signal charge generated by the light entering each of the photoelectric conversion elements 11R, 11L during the accumulation period ΔT exceeds the capacity that can be held in one of the photoelectric conversion elements 11R, 11L, and an overflow from one of the photoelectric conversion elements 11R, 11L to the other occurs, but no overflow into the holding capacitance 13 occurs, then the signal R+L restored by the above processing can be used as a correct imaging data signal.

[0117] However, in this case, the signals R and L become meaningless as phase signals due to overflow from one of the photoelectric conversion elements 11R, 11L to the other, and therefore cannot be used to generate a reliable phase difference data signal.

[0118] In the first pixel 10A, if the signal charge generated by the light incident on each of the photoelectric conversion elements 11R, 11L during the accumulation period ΔT exceeds the capacity that can be held by one of the photoelectric conversion elements 11R, 11L, and an overflow occurs from the photoelectric conversion elements 11R, 11L to the holding capacitance 13, the signal R+L restored by the above process, unlike the above two cases, exceeds the signal amount that the photoelectric conversion elements 11R, 11L can handle, and therefore has no meaning as an imaging data signal. In this case, if the signal from the holding capacitance 13 is used, the signal R+L+C can be used as a correct imaging data signal.

[0119] In this case too, signals R and L have no meaning as phase signals and therefore cannot be used to generate a reliable phase difference data signal.

[0120] Also, when the pixel 10 is the second pixel 10B, the second pixel 10B does not usually generate a useful imaging data signal. On the other hand, in a combination of second pixels 10B in which the phases of received light are complementary, the signal R+L (when no overflow from the photoelectric conversion elements 11R, 11L to the storage capacitor 13 occurs) or the signal R+L+C (when overflow from the photoelectric conversion elements 11R, 11L to the storage capacitor 13 occurs) of each second pixel 10B restored by the above process can be used in the pair of second pixels 10B as a phase signal for generating a reliable phase difference data signal.

[0121] [Example of phase difference data signal output from a solid-state imaging device] As can be understood from the above, the solid-state imaging device 1 of this embodiment includes two means, a means for generating a phase difference data signal from the first pixel 10A and a means for generating a phase difference data signal from the second pixel 10B. These means can be appropriately selected according to the brightness and exposure time of the imaging scene using the solid-state imaging device 1. For example, when the imaging scene has a relatively low brightness or the exposure time (accumulation period ΔT) is relatively short, the possibility of overflow occurring in the photoelectric conversion elements 11R and 11L is low, so it is considered that the phase difference data signal generated in the first pixel 10A that generates imaging data can be effectively utilized. On the other hand, when the imaging scene has a relatively high brightness or the exposure time (accumulation period ΔT) is relatively long, overflow is likely to occur in the photoelectric conversion elements 11R and 11L, and it is difficult to generate a reliable phase difference data signal in the first pixel 10A, so it is considered that it is desirable to utilize the phase difference data signal generated in the second pixel 10B instead. Hereinafter, an example of outputting a phase difference data signal in the pixel array section 2 of the solid-state imaging device 1 of this embodiment will be described.

[0122] 8 is a flowchart showing a first output example of a phase difference data signal from a solid-state imaging device. As shown in FIG 8, the first output example includes the following steps 801 to 803.

[0123] First, in step 801, signal data generated in a plurality of pixels 10 (i.e., the first pixels 10A and the second pixels 10B) included in a certain range of the pixel array section 2 is stored in the memory 8 by, for example, the method shown in the driving example of the pixel 10 described above. The memory 8 is, for example, a line memory, and the line memory stores signal data of the pixels 10 arranged in one or more rows to be read out of the plurality of pixels 10 two-dimensionally arranged in a matrix in the pixel array section 2.

[0124] Next, in step 802, among the pixels 10 related to the signal data stored in this memory 8 (i.e., those that can be referenced on the memory 8), the following processing is performed on the signal data related to the first pixel 10A, thereby outputting a phase difference data signal from each of the first pixels 10A.

[0125] Specifically, for each first pixel 10A that can be referenced on the memory 8, both a phase difference data signal (hereinafter also referred to as a first phase difference data signal) generated based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L of this first pixel 10A, and a phase difference data signal (hereinafter also referred to as a second phase difference data signal) generated based on the signal charges accumulated in a pair of second pixels 10B that can be referenced on the memory 8 are output.

[0126] The set of second pixels 10B referenced to generate the second phase difference data signal to be output as phase difference information of the target first pixel 10A is preferably a set of second pixels 10B in the vicinity of the target first pixel 10A, and more preferably a set in which the average distance between the target first pixel 10A and each of the second pixels 10B constituting the set of second pixels 10B is the shortest among all sets of second pixels 10B that can be referenced on the memory 8.

[0127] Then, in step 803, if there are any pixels 10 remaining in the pixel array section 2 that have not yet been read into the memory 8, the signal data stored in the memory 8 is updated, and the above steps 801 to 802 are repeated until all pixels 10 included in the pixel array section 2 have been read.

[0128] In the case of this first output example, which of the first and second phase difference data signals output from the first pixel 10A of the pixel array unit 2 is to be used can be determined by a control device or the like of a camera device that receives the output signals. Alternatively, both phase difference data signals may be used depending on the output destination.

[0129] 9 is a flowchart showing a second output example of a phase difference data signal from the solid-state imaging device. As shown in FIG 9, the second output example includes the following steps 901 to 903.

[0130] First, in step 901, similarly to the first output example, signal data generated in a plurality of pixels 10 included in a certain range of the pixel array section 2 is accumulated in the memory 8.

[0131] Next, in step 902, for each of the first pixels 10A that can be referenced on the memory 8, whether to output the first phase difference data signal or the second phase difference data signal is selected based on a command from outside the solid-state imaging device 1. This command from outside is issued, for example, by a control device or the like provided in a camera device in which the solid-state imaging device 1 is mounted.

[0132] For example, when the camera device decides not to use the holding capacitance 13 of the pixel 10, i.e., when the HDR mode is not adopted, the control device of the camera device may instruct to output a first phase difference data signal as the phase difference information of the first pixel 10A of interest. On the other hand, when the camera device decides to use the holding capacitance 13 of the pixel 10, i.e., when the HDR mode is adopted, the control device of the camera device may instruct to output a second phase difference data signal as the phase difference information of the first pixel 10A of interest.

[0133] In this case, in many cases, the same mode is adopted for the pixels 10 in the pixel array section 2 as to whether or not to use the holding capacitance 13, based on the settings of the control device of the camera device. However, it is not necessary to adopt the same mode for all the pixels 10 in the pixel array section 2, and a command may be sent to a first pixel 10A arranged in a part of the pixel array section 2 to use the holding capacitance 13, and a command may be sent to the remaining part not to use the holding capacitance 13. For example, among all the pixels 10 provided in the camera device, different commands may be sent according to the positions at which the pixels 10 are arranged, such that the holding capacitance 13 is not used for the pixels 10 near the center that are easy to receive light, and the holding capacitance 13 is used for the pixels 10 near the periphery that are difficult to receive light.

[0134] Then, in step 903, if there are any pixels 10 remaining in the pixel array section 2 that have not yet been read into the memory 8, the signal data stored in the memory 8 is updated, and the above steps 901 to 902 are repeated until all pixels 10 included in the pixel array section 2 have been read.

[0135] In the case of this second output example, the amount of signal output can be reduced compared to the first output example, thereby reducing the signal processing burden on the control device of the camera equipment that receives the output signal.

[0136] 10 is a flowchart showing a second output example of a phase difference data signal from a solid-state imaging device. As shown in FIG 10, the second output example includes the following steps 1001 to 1003.

[0137] First, in step 1001, similarly to the first output example, signal data generated in a plurality of pixels 10 included in a certain range of the pixel array section 2 is accumulated in the memory 8.

[0138] Next, in step 1002, for each of the first pixels 10A that can be referenced on the memory 8, whether to output the first phase difference data signal or the second phase difference data signal is selected based on the judgment of the solid-state imaging device 1 itself. This selection is performed, for example, by the signal processing unit 7 based on various signals of the target first pixel 10A.

[0139] The process for each first pixel 10A in step 1002 is shown in more detail in FIG. 11. In step 1101, the signal processing unit 7 judges whether or not each of the signals R and L based on the signal charges accumulated in the photoelectric conversion elements 11R and 11L for the first pixel 10A of interest has reached a threshold value indicating that an overflow has occurred in the photoelectric conversion elements 11R and 11L. If neither of the signals R nor L has reached the threshold value, in step 1102, a first phase difference data signal is output as the phase difference information for the first pixel 10A of interest. On the other hand, if at least one of the signals R and L has reached the threshold value, an overflow has occurred in the photoelectric conversion elements 11R and 11L, and a reliable phase difference data signal cannot be obtained from the signals R and L. Therefore, in step 1103, a second phase difference data signal is output as the phase difference information for the first pixel 10A of interest. After that, in step 1104, steps 1101 to 1103 are repeated until phase difference data signals for all of the first pixels 10A that can be referenced on the memory 8 are output.

[0140] When the first phase difference data signal is used as the phase difference information of the first pixel 10A, the phase difference data signal generated by comparing the signal R and the signal L in this first pixel 10A is output.

[0141] In addition, when the second phase difference data signal is adopted as the phase difference information of the first pixel 10A, it is preferable to determine whether or not overflow occurs from the photoelectric conversion elements 11R, 11L to the storage capacitor 13 in each pixel constituting the set of the second pixel 10B, and if not, to use the signal R+L of the second pixel 10B as a phase signal for generating a phase difference data signal in the set, and if it occurs, to use the signal R+L+C of the second pixel 10B as the phase signal. Whether or not overflow occurs from the photoelectric conversion elements 11R, 11L to the storage capacitor 13 is determined by, for example, determining whether a threshold value indicating that overflow occurs in both the photoelectric conversion elements 11R, 11L is reached.

[0142] In addition, when overflow from the photoelectric conversion elements 11R and 11L to the storage capacitance 13 does not occur, the signal charge stored in the storage capacitance 13 is theoretically zero. Therefore, even in such a case, it is conceivable that the second pixel 10A generates the signal R+L+C as the phase signal instead of the signal R+L. However, in reality, the signal R+L+C contains signal noise caused by the storage capacitance 13. Therefore, when overflow to the storage capacitance 13 does not occur, it is desirable to use the signal R+L instead of the signal R+L+C as described above in order to increase the signal-to-noise ratio of the phase signal.

[0143] Furthermore, when the second phase difference data signal is output as the phase difference information of the first pixel 10A, it is preferable to appropriately perform a complementation process on the output phase difference data signal so that a device (e.g., a camera device) receiving the output phase difference data signal can handle it in the same way as a phase difference data signal generated based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L of another first pixel 10A.

[0144] Then, in step 1003, if there are any pixels 10 remaining in the pixel array section 2 that have not yet been read into the memory 8, the signal data stored in the memory 8 is updated, and the above steps 1001 to 1002 are repeated until all pixels 10 included in the pixel array section 2 have been read.

[0145] In the case of this third output example, compared to the second output example, the phase difference data signal to be output is selected based on the judgment of the solid-state imaging device 1 itself based on whether or not an overflow has occurred in the photoelectric conversion elements 11R, 11L of the first pixel 10A, so that a more reliable phase difference signal can be output from the solid-state imaging device 1.

[0146] The phase difference data signal output from each pixel 10 in the above manner can be used for performing autofocus in, for example, a camera device including the solid-state imaging device 1. In addition, the phase difference data signal can be used for various purposes other than autofocus, such as depth estimation (depth map). Second Embodiment

[0147] Next, a second embodiment will be described.

[0148] [Structure of solid-state imaging device] The solid-state imaging device 1 of the second embodiment of the present invention is the same as the first embodiment, except that the relationship between the potential barrier between the two photoelectric conversion elements 11R, 11L in the pixel 10 is different from that between the two photoelectric conversion elements 11R, 11L and the storage capacitor 13. Hereinafter, in this embodiment, the components of the solid-state imaging device will be described using the same reference numerals as those in the first embodiment.

[0149] 12 shows the relationship between the potential barrier between the two photoelectric conversion elements 11R, 11L and the potential barrier between the two photoelectric conversion elements 11R, 11L and the storage capacitor 13 in the pixel 10 of the solid-state imaging device 1 of the second embodiment. As shown in FIG. 12, in the pixel 10 of this embodiment, the potential barrier between the two photoelectric conversion elements 11R, 11L is higher than the potential barrier between the two photoelectric conversion elements 11R, 11L and the storage capacitor 13. Therefore, in the pixel 10 of this embodiment, when a signal charge that exceeds the storage capacity that can be stored in one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L) is generated at a time when the transfer transistors 14R, 14L and the storage switch transistor 15 are off, the signal charge overflowing from the one photoelectric conversion element 11R, 11L first exceeds the relatively low potential barrier between the photoelectric conversion elements 11R, 11L and the storage capacitor 13, and flows preferentially into the storage capacitor 13 to be stored therein.

[0150] In this embodiment, even if only one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L) overflows, if the other (for example, the photoelectric conversion element 11R) does not overflow, it is maintained that the source of the signal charge accumulated in the holding capacitance 13 is the one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L), that is, the phase information is maintained in the signal charge accumulated in the holding capacitance 13. Therefore, in this case, a reliable phase difference data signal can be generated by comparing the sum of the signal charge accumulated in the one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L) where the overflow occurred and the signal charge accumulated in the holding capacitance 13 with the signal charge accumulated in the other photoelectric conversion element 11R, 11L (for example, the photoelectric conversion element 11R) where the overflow did not occur. Therefore, according to this embodiment, in an imaging scene with high brightness or long exposure time in which the signal charge generated in the photoelectric conversion elements 11R, 11L would overflow, it is possible to generate a phase difference data signal with higher reliability than in the first embodiment.

[0151] [Example of driving pixels in a solid-state imaging device] The driving timing of the pixel 10 in this embodiment can be the same as that in the first embodiment. By processing the first to fifth signals acquired in driving such a pixel 10, it is possible to restore the signals R, R+L, L, and R+L+C in the same manner as in the first embodiment. Furthermore, in this embodiment, the signal R+C is restored by subtracting the signal R from the signal R+L+C, and the signal L+C is restored by subtracting the signal R from the signal R+L+C.

[0152] Here, in the first pixel 10A, if no overflow occurs from the photoelectric conversion elements 11R, 11L during the accumulation period ΔT, as in the first embodiment, the signal R+L can be used as a correct imaging data signal, and the signals R and L can be used as reliable phase signals from which a correct phase difference data signal can be generated by comparing them.

[0153] On the other hand, in the first pixel 10A, if an overflow occurs in at least one of the photoelectric conversion elements 11R, 11L during the accumulation period ΔT, the signal R+L, unlike the first embodiment, exceeds the signal amount that the photoelectric conversion elements 11R, 11L can handle, and therefore becomes meaningless as an imaging data signal. In this case, the signal R+L+C can be used as a correct imaging data signal.

[0154] In this case, the signals R and L have no meaning as phase signals, and therefore cannot be used to generate a reliable phase difference data signal. However, if only one of the photoelectric conversion elements 11R and 11L is overflowing, a correct phase difference data signal can be generated by adding a signal C to the signal R or L corresponding to the photoelectric conversion element 11R or 11L in which the overflow has occurred, and comparing the signal R or L corresponding to the photoelectric conversion element 11R or 11L in which the overflow has not occurred. For example, if an overflow of the signal charge generated in the photoelectric conversion element 11L has occurred but an overflow has not occurred in the photoelectric conversion element 11R, a correct phase difference data signal can be generated by comparing the signal R with the signal L+C.

[0155] When overflow occurs in both the photoelectric conversion elements 11R and 11L, the signal charge stored in the holding capacitance 13 is a mixture of the signal charges overflowing from both the photoelectric conversion elements 11R and 11L and flowing in. Therefore, in such a case, the signal charge stored in the holding capacitance 13 cannot be used as a phase signal.

[0156] In the second pixel 10B that does not generate an imaging data signal, when no overflow occurs in either of the photoelectric conversion elements 11R, 11L, the signal R+L can be used in the set of second pixels 10B as a phase signal for generating a reliable phase difference data signal, and when an overflow occurs in either of the photoelectric conversion elements 11R, 11L, the signal R+L+C can be used in the set of second pixels 10B as a phase signal for generating a reliable phase difference data signal.

[0157] [Example of phase difference data signal output from a solid-state imaging device] The output of the phase difference data signal from the pixel array unit 2 of the solid-state imaging device 1 of the second embodiment can be performed in the same manner as in the first embodiment, except for the details of step 1002 of the third output example shown below. The process for each first pixel 10A in step 1002 in the second embodiment is shown in more detail in FIG.

[0158] In step 1301, the signal processing unit 7 determines whether or not each of the signals R and L based on the signal charges accumulated in the photoelectric conversion elements 11R and 11L for the first pixel 10A under consideration has reached a threshold value indicating that an overflow has occurred in the photoelectric conversion elements 11R and 11L.

[0159] If neither signal R nor signal L has reached the threshold, then in step 1302, output a first phase difference data signal generated by comparing signal R and signal L at this first pixel 10A.

[0160] On the other hand, if one of the signals R and L has reached the threshold value, i.e., if an overflow has occurred in one of the photoelectric conversion elements 11R, 11L, in step 1303, a phase difference data signal (also referred to as a first phase difference signal to which an overflow capacitance has been added) generated by adding a signal C to the signal R, L in the first pixel 10A that corresponds to the photoelectric conversion element 11R, 11L in which an overflow has occurred, and comparing the signal corresponding to the photoelectric conversion element 11R, 11L in which an overflow has not occurred with the signal C is output.

[0161] On the other hand, when both the signals R and L have reached the threshold value, the signal charges overflowing from both the photoelectric conversion elements 11R and 11L flow into the storage capacitor 13, and the signal C based on the storage capacitor 13 does not hold phase information, so in step 1304, a second phase difference data signal is output as the phase difference information of the target first pixel 10A. This step 1304 can be performed in the same manner as step 1103 in the first embodiment.

[0162] After that, in step 1305, steps 1301 to 1304 are repeated until phase difference data signals for all the first pixels 10A that can be referenced on the memory 8 are output.

[0163] The solid-state imaging device of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, part of the configuration of one embodiment can be deleted.

[0164] Specifically, in the first and second embodiments described above, a set of two or more second pixels 10B configured to be capable of generating a phase difference data signal of received light is used as the second pixel 10B, the light receiving surface of which is partially shielded from light by an opaque film 60; however, the second pixel in the present invention is not limited to this form.

[0165] For example, as the set of second pixels, a set of two or more second pixels 10B' sharing one on-chip lens 30' may be adopted as the set of second pixels, as in the example shown in Figures 14 and 15. In this example, two second pixels 10B' are adjacently arranged in a set in the pixel array unit 2', and one on-chip lens 30' is independently provided for each set of second pixels 10B'. In this example, too, the signal charge generated by the second pixel 10B' can be processed in the same manner as in the first and second embodiments described above to output a phase difference data signal.

[0166] Furthermore, in the first and second embodiments described above, the pixel 10 includes two photoelectric conversion elements 11R, 11L, but the number of photoelectric conversion elements included in the pixel 10 is not limited to two and may be three or more. Also, only the first pixel 10A needs to include two or more photoelectric conversion elements 11R, 11L, and the second pixel 10B may include only one photoelectric conversion element.

[0167] Directional terms such as "upper," "lower," "left," and "right" mentioned in the above-described embodiments mean directions such as up, down, left, and right in the drawings, unless otherwise specified, and do not limit the directions of the embodiments of the present invention.

[0168] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments with reference to the drawings in the above description, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0169] 1...solid-state imaging device, 2...pixel array section, 21...row signal line, 22...column signal line, 3...vertical drive section, 4...column signal processing section, 5...horizontal drive section, 6...control section, 7...signal processing section, 8...memory (storage section), 10A, 10B...pixel, 11R, 11L...photoelectric conversion element, 12...floating diffusion, 13...retention capacitance, 14R, 14L...transfer transistor (first switch transistor), 15...retention switch transistor, first retention switch transistor (second switch transistor), 16...reset transistor (third switch transistor), 17...amplification transistor, 18...selection transistor, 20...semiconductor region, 30...on-chip lens, 40...color filter, 50...transparent film, 60...opaque film, SF...source follower circuit, VDD1...reset power supply (reset potential), VDD2...power supply, φRES, φS, φS1, φSEL, φTX_R, φTX_L...drive signal

Claims

1. A solid-state imaging device including a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels, Each of the first pixels and the second pixels includes one or more photoelectric conversion elements that configure a light receiving surface of the pixel and generate electric charges by photoelectrically converting received light; a floating diffusion connected to the one or more photoelectric conversion elements and configured to convert the electric charge into a voltage corresponding to the amount of the electric charge; a storage capacitor connected to the floating diffusion and capable of storing the charge overflowing from the one or more photoelectric conversion elements; Equipped with each of the plurality of first pixels includes two or more of the photoelectric conversion elements, the floating diffusion is connected to all of the two or more photoelectric conversion elements, and is configured to generate a phase difference data signal by comparing the charges accumulated in the two or more photoelectric conversion elements, Two or more of the second pixels among the plurality of second pixels together constitute a second pixel set; the second pixel set is configured to generate a phase difference data signal by comparing the charges stored in the second pixels constituting the second pixel set, In each of the plurality of second pixels, generating a phase difference data signal based on the sum of the charges accumulated in the one or more photoelectric conversion elements when the sum of the charges accumulated in the one or more photoelectric conversion elements is equal to or less than a predetermined saturation charge amount; A solid-state imaging device that generates a phase difference data signal based on the sum of the charges stored in the one or more photoelectric conversion elements and the charge stored in the storage capacitor when the sum of the charges stored in the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount.

2. 2. The solid-state imaging device according to claim 1, wherein in each of the two or more pixels constituting the second pixel set, a portion of the light receiving surface of the pixel is masked so as to prevent light from being received on that portion of the light receiving surface.

3. Each of the plurality of first pixels is independently provided with one on-chip lens (OCL); 2. The solid-state imaging device according to claim 1, wherein each of the second pixel sets is independently provided with one on-chip lens (OCL), and the two or more pixels constituting the second pixel set share the one on-chip lens (OCL).

4. In each of the plurality of first pixels, 4. The solid-state imaging device according to claim 1, wherein a potential barrier between the two or more photoelectric conversion elements is lower than a potential barrier between the photoelectric conversion element and the storage capacitor.

5. In each of the plurality of first pixels, 4. The solid-state imaging device according to claim 1, wherein a potential barrier between the two or more photoelectric conversion elements is higher than a potential barrier between the photoelectric conversion element and the storage capacitor.

6. The solid-state imaging device, for each of the plurality of first pixels, A solid-state imaging device according to any one of claims 1 to 3, which determines whether the charges held in each of the two or more photoelectric conversion elements have reached a threshold value indicating that an overflow has occurred in the photoelectric conversion element, and if none of the charges have reached the threshold value, outputs a phase difference data signal generated based on the charges generated in the two or more photoelectric conversion elements in the first pixel, and if at least one of the charges has reached the threshold value, outputs a phase difference data signal generated based on the charges generated in the second pixel set determined by the solid-state imaging device.

7. A solid-state imaging device according to any one of claims 1 to 3, and a control device configured to control the solid-state imaging device.

8. 8. The camera device according to claim 7, wherein the solid-state imaging device is configured to determine, based on a signal from the control device, whether to output a phase difference data signal for each pixel based on the charge generated in the two or more photoelectric conversion elements of the first pixel, and / or whether to output a phase difference data signal for each pixel based on the charge generated in the set of two or more second pixels.

9. The camera device of claim 7 , wherein the camera device is a mobile terminal.

Images