Image sensor

Abstract

An image sensor is provided. An image sensor operating in multiple resolution modes, including a low-resolution mode and a high-resolution mode, includes: a pixel array comprising a plurality of pixels, wherein each of the plurality of pixels includes: a first sub-pixel having a first photodiode and a second sub-pixel having a second photodiode, and the first sub-pixel and the second sub-pixel are disposed adjacent to each other and share a floating diffusion region. The image sensor further includes a row driver providing control signals to the pixel array to control the execution of an autofocus (AF) function, such that the execution of the AF function includes: performing the AF function on a pixel-by-pixel basis in the high-resolution mode, and performing the AF function on a group-by-pixel basis in the low-resolution mode.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefits of Korean Patent Application No. 10-2019-0053242 filed with the Korean Intellectual Property Office on May 7, 2019 and Korean Patent Application No. 10-2019-0100535 filed with the Korean Intellectual Property Office on August 16, 2019, the general subject matter of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to image sensors, and more specifically, to image sensors comprising multiple pixels, wherein each pixel comprises multiple sub-pixels having photodiodes. Background Technology

[0004] Image sensors consist of an array of pixels. Each pixel in the pixel array may include a photodiode. Some image sensors can perform autofocus (AF) to improve the accuracy of object imaging. Summary of the Invention

[0005] The present invention provides an image sensor capable of accurately performing autofocus functions under various lighting conditions.

[0006] According to one aspect of the present invention, an image sensor is provided that is selectively adaptable for use in multiple resolution modes, including a low-resolution mode and a high-resolution mode. The image sensor includes a pixel array comprising a plurality of pixels, wherein each of the plurality of pixels includes a first sub-pixel having a first photodiode and a second sub-pixel having a second photodiode, and the first sub-pixel and the second sub-pixel are disposed adjacent to each other and share a floating diffusion region. The image sensor further includes a row driver that provides control signals to the pixel array to control the execution of an autofocus (AF) function, such that the execution of the AF function includes: performing the AF function on a pixel-by-pixel basis in the high-resolution mode, and performing the AF function on a group-by-pixel basis in the low-resolution mode. The resolution corresponding to the low-resolution mode is equal to or less than 1 / 4 of the resolution corresponding to the high-resolution mode.

[0007] According to another aspect of the present invention, an image sensor is provided that is selectively adaptable for use in multiple resolution modes, including a low-resolution mode, a medium-resolution mode, and a high-resolution mode. The image sensor includes: a pixel array comprising a plurality of pixels arranged along row and column directions, wherein each of the plurality of pixels has a shared pixel structure. The shared pixel structure includes: a first sub-pixel including a first photoelectric conversion element, which selectively transfers photoelectric charge to a floating diffusion region via a first transmission transistor in response to a first transmission signal; a second sub-pixel including a second photoelectric conversion element, which selectively transfers photoelectric charge to the floating diffusion region via a second transmission transistor in response to a second transmission signal; a reset transistor configured to selectively reset the photoelectric charge accumulated in the floating diffusion region in response to a reset signal; and a drive transistor and a selection transistor selectively connecting the floating diffusion region to a pixel signal output terminal in response to a selection signal, wherein the floating diffusion region, the reset transistor, the drive transistor, and the selection transistor are shared by the first sub-pixel and the second sub-pixel, and the first sub-pixel and the second sub-pixel are arranged adjacent to each other. The image sensor further includes a row driver configured to provide the first transmission signal, the second transmission signal, the reset signal, and the selection signal, such that the execution of the autofocus (AF) function includes: performing the AF function on a pixel-by-pixel basis in the high-resolution mode; performing the AF function on a pixel-by-pixel basis in the medium-resolution mode; and performing the AF function on a pixel-by-pixel basis in the low-resolution mode.

[0008] According to another aspect of the present invention, an image sensor is selectively adaptable for use in multiple resolution modes, including a low-resolution mode, a medium-resolution mode, and a high-resolution mode. The image sensor includes: a row driver; a controller configured to control the operation of the row driver; and a pixel array including a plurality of pixels arranged along row and column directions, the plurality of pixels being configured to provide a pixel signal in response to received incident light, wherein each of the plurality of pixels includes: a first sub-pixel having a first photodiode and a second sub-pixel having a second photodiode, the first sub-pixel and the second sub-pixel being disposed adjacently and sharing a floating diffusion region, wherein the row driver is configured to provide a control signal to the pixel array to control the execution of an autofocus (AF) function, such that the execution of the AF function includes: in the high-resolution mode, performing the AF function on a pixel-by-pixel basis; in the medium-resolution mode, performing the AF function on a pixel-by-pixel basis, in a group of pixels arranged in the same row; and in the low-resolution mode, performing the AF function on a group-by-pixel basis. Attached Figure Description

[0009] Embodiments of the inventive concept can be more clearly understood based on the following detailed description taken in conjunction with the accompanying drawings, in which:

[0010] Figure 1 This is a block diagram illustrating a digital imaging device according to an embodiment of the concept of the present invention;

[0011] Figure 2 This is further illustrated in one embodiment. Figure 1 Block diagram of image sensor 100;

[0012] Figure 3A , Figure 3B , Figure 4A , Figure 4B and Figure 4C This further demonstrates Figure 2 Various illustrations of certain aspects of the pixel array 110 of the image sensor 100;

[0013] Figure 5 This is a circuit diagram illustrating the arrangement of the first and second sub-pixels of a shared floating diffusion region in one embodiment;

[0014] Figure 6A , Figure 6B , Figure 6C , Figure 6D and Figure 6E This further demonstrates Figure 3A The first sub-pixel array includes multiple sub-pixels sharing a floating diffusion region;

[0015] Figure 7 This is a circuit diagram illustrating the arrangement of sub-pixels sharing a floating diffusion region in one embodiment;

[0016] Figure 8 , Figure 9 , Figure 10 and Figure 11 This is further illustrated in some embodiments. Figure 2 Timing diagrams showing the specific timing relationships between various control signals during the operation of the image sensor 100; and

[0017] Figure 12 This is further illustrated in yet another embodiment. Figure 2 A diagram of pixel array 110. Detailed Implementation

[0018] Figure 1 This is a block diagram illustrating a digital imaging device 1000 according to an embodiment of the concept of the present invention.

[0019] Reference Figure 1The digital imaging device 1000 typically includes an imaging unit 1100, an image sensor 100, and a processor 1200. Here, it is assumed that the digital imaging device 1000 is capable of performing focus detection.

[0020] The overall operation of the digital imaging device 1000 can be controlled by the processor 1200. Figure 1 In the illustrated embodiment, it is assumed that processor 1200 provides certain signals to control various components of digital imaging device 1000. For example, processor 1200 may provide lens driver signals applied to lens driver 1120, aperture driver signals applied to aperture driver 1140, and controller signals applied to controller 120.

[0021] Imaging unit 1100 typically includes one or more elements configured to receive incident light associated with object 2000 being imaged by digital imaging device. In this regard, object 2000 can be a single object, a set of objects, or a distributed field of objects. Furthermore, the term "incident light" should be interpreted broadly to represent any selected range of electromagnetic energy within one or more frequency bands (e.g., wavelengths perceptible to the human eye) of the electromagnetic spectrum capable of being imaged by digital imaging device 1000.

[0022] exist Figure 1 In the illustrated embodiment, the imaging unit 1100 includes a lens driver 1120 and an aperture driver 1140, as well as a lens 1110 and an aperture 1130. Here, the lens 1110 may include one or more lenses arranged individually or in combination to effectively capture incident light associated with the object 2000.

[0023] Specifically, the lens driver 1120 is used to control the operation of the lens 1110 to accurately capture the incident light associated with the object 2000. Therefore, the lens driver 1120 responds to focus detection functions performed by the digital imaging device 1000, such as those sent by the processor 1200. In this way, the focal position of the lens 1110 can be controlled by one or more control signals provided from the processor 1200.

[0024] In this regard, it should be noted that the term “control signal” is used below to refer to one or more signals (which are analog or digital in nature and have various formats) used to adjust or control the operation of components within the digital imaging device 1000.

[0025] Therefore, the lens driver 1120 can adjust the focal position of the lens 1110 according to the movement, orientation and / or distance of the object 2000 relative to the lens 1110, so as to correct the focal mismatch between the given focal position of the lens 1110 and the object 2000.

[0026] exist Figure 1 In the illustrated embodiment, the image sensor 100 can be used to convert incident light received via the imaging unit 1100 into a corresponding image signal. The image sensor 100 typically includes a pixel array 110, a controller 120, and a signal processor 130. Here, incident light passing through the lens 1110 and the aperture 1130 reaches the incident light receiving surface of the pixel array 110.

[0027] The pixel array 110 may include a complementary metal-oxide-semiconductor (CMOS) image sensor (CIS) capable of converting the energy of incident light into one or more corresponding electrical signals. In this regard, the sensitivity of the pixel array 110 may be adjusted by the controller 120. The resulting set of corresponding electrical signals may be further processed by the signal processor 130 to provide an image signal.

[0028] In some embodiments of the present invention, pixel array 110 may include a plurality of pixels capable of selectively performing autofocus (AF) or distance measurement functions.

[0029] Therefore, in some embodiments of the present invention, processor 1200 may receive a first image signal and a second image signal from signal processor 130, and perform phase difference determination using the first image signal and the second image signal. Processor 1200 may then determine an appropriate focal position, identify a focusing direction, and / or calculate the distance between the digital imaging device and the object 2000 based on the result of the phase difference determination. In this way, processor 1200 may be used to provide one or more signals applied to lens driver 1120 to appropriately adjust the focal position of lens 1110 based on the result of the phase difference determination operation.

[0030] Figure 2 This is further illustrated in one embodiment. Figure 1 A block diagram of the image sensor 100. Here, the image sensor 100 can be selectively adapted for use in various resolution modes in response to the lighting environment associated with the object 2000. That is, in some embodiments of the inventive concept, Figure 1 The digital imaging device can determine the appropriate resolution mode (e.g., low or high) and selectively adapt (or configure) the image sensor 100 accordingly.

[0031] Reference Figure 2In addition to the pixel array 110, controller 120, and signal processor 130, the image sensor 100 also includes a row driver 140 and a signal readout unit 150. Here, it is assumed that the signal readout unit 150 includes a correlated double sampling circuit (CDS) 151, an analog-to-digital converter (ADC) 153, and a buffer 155.

[0032] Pixel array 110 includes a plurality of pixels. These plurality of pixels may include one or more sub-pixel arrays (or may be functionally divided into one or more sub-pixel arrays) that are differently designated for various operations. For example, pixel array 110 may include a first sub-pixel array 110_1 and a second sub-pixel array 110_2. In some embodiments of the present invention, the first sub-pixel array 110_1 includes a plurality of horizontal pixels PX_X capable of performing AF functionality in a first direction (e.g., row direction), and the second sub-pixel array 110_2 includes a plurality of vertical pixels PX_Y capable of performing AF functionality in a second direction (e.g., column direction). In some embodiments of the present invention, each sub-pixel array may also be functionally divided into two (2) or more pixel groups.

[0033] Those skilled in the art will recognize that the terms “horizontal” and “vertical”, “first direction” and “second direction”, and “row direction” and “column direction” are inherently relative and are used to describe various relative orientational relationships between the enumerated elements and components.

[0034] Each horizontal pixel PX_X of the first sub-pixel array 110_1 includes at least two (2) photodiodes arranged adjacently in a first direction (or row direction) of a matrix arrangement comprising at least one row. Each horizontal pixel PX_X of the first sub-pixel array 110_1 also includes a microlens ML disposed on the at least two (2) photodiodes.

[0035] Each vertical pixel PX_Y of the second sub-pixel array 110_2 includes at least two (2) photodiodes disposed adjacently in a second direction (or column direction) of a matrix comprising at least one column. Each vertical pixel PX_Y of the second sub-pixel array 110_2 also includes a microlens ML disposed on the at least two (2) photodiodes.

[0036] With this configuration, each horizontal pixel PX_X of the first sub-pixel array 110_1 can perform AF functionality in a first direction, and each vertical pixel PX_Y of the second sub-pixel array 110_2 can perform AF functionality in a second direction. Since each horizontal pixel PX_X and each vertical pixel PX_Y includes at least two photodiodes and a microlens, each pixel in the plurality of pixels (including both the horizontal PX_X pixel and the vertical PX_Y pixel) can generate a pixel signal capable of effectively performing AF functionality. In this way, the image sensor according to an embodiment of the present invention can easily provide enhanced AF functionality.

[0037] In some embodiments of the present invention, the width of each horizontal pixel PX_X of the first sub-pixel array 110_1 can be in the range of approximately 0.5 μm to approximately 1.8 μm. The width of each vertical pixel PX_Y of the second sub-pixel array 110_2 can also be in the range of approximately 0.5 μm to approximately 1.8 μm. Alternatively, the widths of the plurality of horizontal and vertical pixels PX_X and PX_Y can be in the range of approximately 0.64 μm to approximately 1.4 μm.

[0038] In some embodiments of the present invention, the horizontal pixels PX_X of the first sub-pixel array 110_1 can be grouped into one or more pixel groups, and the vertical pixels PX_Y of the second sub-pixel array 110_2 can be grouped into one or more pixel groups.

[0039] Based on a given configuration and definition of multiple pixels and pixel groups Figure 2 The image sensor 100 can selectively perform AF function on a pixel-by-pixel or pixel-by-pixel basis. For example, if Figure 1 If the digital imaging device 1000 is suitable for high-resolution mode, then the image sensor can perform AF function on a pixel-by-pixel basis (i.e., in response to various pixel signals provided by individual pixels (e.g., horizontal and / or vertical pixels)). Alternatively, if Figure 1 If the digital imaging device 1000 is suitable for low-resolution mode, then the image sensor can perform AF function on a per-pixel basis (i.e., in response to various (one or more) pixel signals provided by the pixel group).

[0040] The following will refer to Figure 3A and Figure 3B The description further illustrates various embodiments of possible configurations of the first subpixel array 110_1 and the second subpixel array 110_2.

[0041] return Figure 2Each pixel in pixel array 110 can output a pixel signal to CDS 151 via one of the first column output lines CLO_0 to the (n-1)th column output lines CLO_n-1 (see, for example, [link to relevant documentation]). Figure 5 The pixel signals output from the horizontal pixel PX_X of the first sub-pixel array 110_1 and the vertical pixel PX_Y of the second sub-pixel array 110_2 can be phase signals used to calculate the phase difference. The phase signal can include information associated with the positioning of one or more objects imaged by the image sensor 100. Therefore, the phase difference can be calculated in response to the calculated phase difference. Figure 1 The focal position of lens 1110. For example, the focal position of lens 1110 corresponding to a phase difference of "0" can be considered the optimal focal position. In some embodiments of the inventive concept, assuming operation in high-resolution mode, the AF function can be performed using multiple pixels (e.g., including horizontal pixels PX_X and vertical pixels PX_Y) that can be selected from pixel array 110. In practice, in some embodiments, when the digital imaging device 100 operates in high-resolution mode, all horizontal pixels in the first sub-pixel array 110_1 and all vertical pixels in the second sub-pixel array 110_2 can be used together to perform the AF function.

[0042] Alternatively or concurrently, the horizontal pixels PX_X of the first sub-pixel array 110_1 and the vertical pixels PX_Y of the second sub-pixel array 110_2 can be used to measure the distance between the object 2000 and the digital imaging device 1000. To measure the distance between the digital imaging device 100 and the object 2000, some additional information may be necessary or convenient to use. Examples of additional information may include: the phase difference between the object 2000 and the image sensor 100, the lens size of the lens 1110, the current focal position of the lens 1110, etc.

[0043] exist Figure 2 In the illustrated embodiment, controller 120 can be used to control row driver 140 such that pixel array 110 effectively captures incident light to effectively accumulate corresponding photoelectric charge (or temporarily stores the accumulated photoelectric charge). Here, the term "photoelectric charge" is used to refer to the charge generated by at least one sub-pixel in the pixel array in response to incident light. The pixel array can then output an electrical signal (i.e., a pixel signal) corresponding to the accumulated photoelectric charge. Additionally, controller 120 can control the operation of signal readout unit 150 such that pixel array 110 can accurately measure the level of the pixel signal provided by pixel array 110.

[0044] The row driver 140 can be used to generate various control signals. Examples of control signals here include a reset control signal RS, a transfer control signal TS, and a select signal SELS, which can be provided differently to control the operation of the pixel array 110. Those skilled in the art will recognize that the selection, number, and definition of the various control signals are a matter of design choice.

[0045] In some embodiments of the present invention, the row driver 140 may be used to determine the activation timing and / or deactivation timing (hereinafter, individually or collectively “activation / deactivation”) of the reset control signal RS, the transmission control signal TS, and the selection signal SELS provided to the horizontal pixel PX_X of the first sub-pixel array 110_1 and the vertical pixel PX_Y of the second sub-pixel array 110_2, respectively, in response to various factors such as high / low resolution operating mode, the type of AF function being performed, distance measurement function, etc.

[0046] The CDS 151 can sample and hold pixel signals provided from the pixel array 110. The CDS 151 can double-sample the level of a specific noise and the level of the pixel signal to output a level corresponding to the difference between them. Furthermore, the CDS 151 can receive a ramp signal generated by the ramp signal generator 157 and can compare the ramp signal with the pixel signal to output a comparison result. The ADC 153 can convert an analog signal corresponding to the level received from the CDS 151 into a digital signal. The buffer 155 can latch the digital signal, and the latched digital signal can be sequentially output to the signal processor 130 or an external device of the image sensor 100.

[0047] Signal processor 130 can perform signal processing based on the digital signal received from buffer 155. For example, signal processor 130 can perform noise reduction, gain adjustment, waveform normalization, interpolation, white balance, gamma adjustment, edge enhancement, etc. Furthermore, signal processor 130 can output information obtained through signal processing performed in AF operation to processor 1200, allowing processor 1200 to perform phase difference operations required for AF operation. In embodiments, signal processor 130 may include a processor disposed outside image sensor 100. Figure 1 (of 1200).

[0048] Figure 3A and Figure 3B This is further illustrated in some embodiments. Figure 2 The individual illustrations of the pixel array 110. Figure 3A This is a further illustration of the first sub-pixel array 110_1 of the pixel array 110 in one embodiment. Figure 3BThis is a further illustration of the second sub-pixel array 110_2 of the pixel array 110 in another embodiment.

[0049] Reference Figure 3A The first subpixel array 110_1 includes a plurality of horizontal pixels PX_X arranged in a matrix defined according to the row direction (i.e., the first direction X) and the column direction (i.e., the second direction Y). Each horizontal pixel PX_X in the first subpixel array 110_1 may include a microlens ML.

[0050] exist Figure 3A In the example shown, the first sub-pixel array 110_1 includes first to fourth pixel groups PG1, PG2, PG3, and PG4. The first pixel group PG1 and the second pixel group PG2 are set to be adjacent in the first direction X, while the third pixel group PG3 and the fourth pixel group PG4 are set to be adjacent in the first direction X. The first pixel group PG1 and the third pixel group PG3 are set to be adjacent in the second direction Y, while the second pixel group PG2 and the fourth pixel group PG4 are set to be adjacent in the second direction Y.

[0051] exist Figure 3A In the illustrated embodiment, the first pixel group, the second pixel group, the third pixel group, and the fourth pixel group PG1 to PG4 each include four (4) horizontal pixels PX_X, but other embodiments of the present invention are not limited to this configuration. For example, the first pixel group, the second pixel group, the third pixel group, and the fourth pixel group PG1 to PG4 may each include eight (8) horizontal pixels PX_X arranged in two (2) rows and four (4) columns.

[0052] However, here, the first pixel group PG1 includes first to eighth sub-pixels SPX11 to SPX18, wherein the first sub-pixel SPX11 and the second sub-pixel SPX12 are configured in a horizontal pixel PX_X, the third sub-pixel SPX13 and the fourth sub-pixel SPX14 are configured in another horizontal pixel PX_X, the fifth sub-pixel SPX15 and the sixth sub-pixel SPX16 are configured in another horizontal pixel PX_X, and the seventh sub-pixel SPX17 and the eighth sub-pixel SPX18 are configured in another horizontal pixel PX_X.

[0053] With a similar configuration, the second pixel group PG2 includes the first to eighth sub-pixels SPX21 to SPX28; the third pixel group PG3 includes the first to eighth sub-pixels SPX31 to SPX38; and the fourth pixel group PG4 includes the first to eighth sub-pixels SPX41 to SPX48.

[0054] Here it should be noted that each horizontal pixel PX_X includes two (2) sub-pixels that are set adjacent to each other in the first direction X.

[0055] The first sub-pixel array 110_1 may also include one or more color filters, such that each horizontal pixel, each set(s) of horizontal pixels, and / or each group of pixels can selectively sense various light wavelengths, such as light wavelengths conventionally associated with different colors of the visible spectrum. For example, in some embodiments of the inventive concept, the various color filters(s) associated with the first sub-pixel array 110_1 may include a red color filter (R) for sensing red, a green color filter (G) for sensing green, and a blue color filter (B) for sensing blue. That is, various color filters (e.g., a first color filter, a second color filter, etc.) can be selected from a set of color filters including a red color filter, a blue color filter, a green color filter, a white color filter, a yellow color filter, etc.

[0056] Here, the first pixel group, the second pixel group, the third pixel group, and the fourth pixel group PG1 to PG4 can each be associated with one or more color filters.

[0057] In the concept of this invention and Figure 3A In one embodiment with the consistent configuration shown, the first pixel group, the second pixel group, the third pixel group, and the fourth pixel groups PG1 to PG4 can be set in the first sub-pixel array 110_1 according to the Bayer pattern. That is, the first pixel group PG1 and the fourth pixel group PG4 can be associated with the green filter (G), the second pixel group PG2 can be associated with the red filter (R), and the third pixel group PG3 can be associated with the blue filter (B).

[0058] However, the foregoing embodiments of the first subpixel array 110_1 are merely one example of many different configurations in which a color filter is associated differently with one or more pixels selected from one or more groups of pixels. Additionally or alternatively, embodiments of the inventive concept may differently include: a white color filter, a yellow color filter, a cyan color filter, and / or a magenta color filter.

[0059] Reference Figure 3A The sub-pixels SPX11 to SPX18, SPX21 to SPX28, SPX31 to SPX38, and SPX41 to SPX48 included in the first sub-pixel array 110_1 can each include a corresponding photodiode. Therefore, each horizontal pixel PX_X will include at least two (2) photodiodes arranged adjacent to each other in the first direction X. The microlens ML can be disposed on at least two (2) photodiodes.

[0060] Given this exemplary configuration, the amount of photoelectric charge generated by the at least two (2) photodiodes included in each horizontal pixel PX_X will vary with the shape and / or refractive index of the associated microlens ML. Therefore, the AF function performed in the first direction X can be based on the pixel signal corresponding to the amount of photoelectric charge generated by the at least two (2) photodiodes.

[0061] For example, the AF function can be performed using the pixel signal output by the first sub-pixel SPX11 of the first pixel group PG1 and the pixel signal output by the second sub-pixel SPX12 of the first pixel group PG1. Therefore, the image sensor according to an embodiment of the present invention can selectively perform the AF function on a pixel-by-pixel basis in a first operating (e.g., high-resolution) mode. Performing the AF function in high-resolution mode according to "pixel units" allows for the selective use of one, more than one, or all of the horizontal pixels PX_X in the first sub-pixel array 110_1 during the execution of the AF function.

[0062] In contrast, the image sensor according to an embodiment of the present invention can selectively perform AF function on a pixel-group basis in a second operating (e.g., low-resolution) mode. Performing AF function on a "pixel-group basis" in low-resolution mode allows selective use of one, more than one, or all pixel groups (e.g., PG1, PG2, PG3, and PG4) of the first sub-pixel array 110_1 during AF function execution. For example, the AF function can be performed by processing a first pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the first sub-pixels SPX11, third sub-pixels SPX13, fifth sub-pixels SPX15, and seventh sub-pixels SPX17 of the first pixel group PG1, and a second pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the second sub-pixels SPX12, fourth sub-pixels SPX14, sixth sub-pixels SPX16, and eighth sub-pixels SPX18 of the first pixel group PG1. If the image sensor 100 performs the AF function in this selective manner, the image sensor according to an embodiment of the present invention can perform the AF function faithfully even under environmental conditions where the pixel array 110 captures a relatively low level of incident light (e.g., the level of incident light is insufficient to accurately perform the AF function under normal circumstances).

[0063] In this regard, those skilled in the art will recognize that the terms “high resolution” and “low resolution” are relative terms and can be arbitrarily defined according to the design. However, in the context of certain embodiments of the inventive concept, a first level of image resolution associated with a low-resolution mode can be understood as less than or equal to one-quarter of a second level of image resolution associated with a high-resolution mode.

[0064] In light of the foregoing, other embodiments of the present invention can provide a digital imaging device capable of operating in more than two resolution modes (or, selectively applicable to more than two resolution modes). For example, a digital imaging device according to certain embodiments of the present invention can be selectively applicable to the low-resolution mode and high-resolution mode as described above, and additionally applicable to the medium-resolution mode. Here, for example, an image sensor according to embodiments of the present invention can perform AF function on a pixel-by-pixel basis by selecting a set of horizontal pixels PX_X (or a set of vertical pixels PX_Y arranged in the same column) included in a single pixel group (e.g., PG1) and arranged in the same row.

[0065] Extending this example, the AF function can be performed by processing a first pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the first sub-pixels SPX11 and SPX13 of the first pixel group PG1, and a second pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the second sub-pixels SPX12 and SPX14 of the first pixel group PG1. Alternatively, the AF function can be performed by processing a first pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the first sub-pixels SPX11 and SPX15 of the first pixel group PG1, and a second pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the second sub-pixels SPX12 and SPX16 of the first pixel group PG1.

[0066] It is recognized here again that the terms “high resolution,” “medium resolution,” and “low resolution” are relative terms and can be arbitrarily defined according to the design. In the context of certain embodiments of the inventive concept, the third level of image resolution associated with the medium resolution mode can be understood as being greater than 1 / 4 of the second level of image resolution associated with the high resolution mode, but less than 1 / 2 of the second level of image resolution associated with the high resolution mode.

[0067] Reference Figure 3B The second subpixel array 110_2 includes a plurality of vertical pixels PX_Y arranged in a matrix defined with respect to a first direction X and a second direction Y. In some embodiments, each vertical pixel PX_Y may include a single microlens ML.

[0068] like Figure 3BAs shown, the second sub-pixel array 110_2 includes a first pixel group, a second pixel group, a third pixel group, and a fourth pixel group PG1Y to PG4Y. However, other embodiments of the present invention may include fewer or more pixel groups. Here, the first pixel group PG1Y includes first to eighth sub-pixels SPX11Y to SPX18Y. The first sub-pixel SPX11Y and the second sub-pixel SPX12Y are configured as one vertical pixel PX_Y, the third sub-pixel SPX13Y and the fourth sub-pixel SPX14Y are configured as another vertical pixel PX_Y, the fifth sub-pixel SPX15Y and the sixth sub-pixel SPX16Y are configured as another vertical pixel PX_Y, and the seventh sub-pixel SPX17Y and the eighth sub-pixel SPX18Y are configured as another vertical pixel PX_Y. Furthermore, for example, the second pixel group PG2Y may include the first to eighth sub-pixels SPX21Y to SPX28Y, the third pixel group PG3Y may include the first to eighth sub-pixels SPX31Y to SPX38Y, and the fourth pixel group PG4Y may include the first to eighth sub-pixels SPX41Y to SPX48Y. That is, a pixel PX_Y may include two sub-pixels that are adjacent to each other in the second direction Y.

[0069] As mentioned above Figure 3A As described, each vertical pixel of the second subpixel array 110_2 or various sets of each vertical pixel of the second subpixel array 110_2 may be associated differently with one or more color filters.

[0070] Therefore, each of the sub-pixels SPX11Y to SPX18Y, SPX21Y to SPX28Y, SPX31Y to SPX38Y, and SPX41Y to SPX48Y included in the second sub-pixel array 110_2 may include a corresponding photodiode. Thus, each vertical pixel PX_Y will include at least two (2) photodiodes arranged adjacent to each other in the second direction Y. The amount of photoelectric charge generated by the at least two (2) photodiodes included in the vertical pixel PX_Y may vary depending on the shape and / or refractive index of the associated microlens ML. The AF function in the second direction Y can be performed based on a pixel signal corresponding to the amount of photoelectric charge generated by the photodiode included in a pixel PX_Y. For example, the AF function can be performed using a first pixel signal output by the first sub-pixel SPX11Y of the first pixel group PG1Y and a second pixel signal output by the second sub-pixel SPX12Y of the first pixel group PG1Y. Therefore, the image sensor according to the embodiment can perform AF function on a pixel-by-pixel basis in high-resolution mode.

[0071] On the other hand, the image sensor according to an embodiment of the present invention can perform AF function on a pixel-by-pixel basis in low-resolution mode. For example, the AF function in the second direction Y can be performed by processing a first pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the first sub-pixels SPX11Y, third sub-pixels SPX13Y, fifth sub-pixels SPX15Y, and seventh sub-pixels SPX17Y of the first pixel group PG1Y, and a second pixel signal corresponding to the amount of photoelectric charge generated by the photodiodes of each of the second sub-pixels SPX12Y, fourth sub-pixels SPX14Y, sixth sub-pixels SPX16Y, and eighth sub-pixels SPX18Y of the first pixel group PG1Y.

[0072] As mentioned above Figure 3A Similar to the embodiments, except that it can operate in high-resolution mode and low-resolution mode, it can also... Figure 3B The embodiment in the example has been changed to operate in medium resolution mode.

[0073] Figure 4A , Figure 4B and Figure 4C This is further illustrated in the various embodiments. Figure 2 The image sensor 100 has a pixel array 110, and each pixel is shown in the diagram. Figure 3A , Figure 4A , Figure 4B and Figure 4C Similar icon numbers and labels are used.

[0074] Reference Figure 4A The horizontal pixels PX_X of the first sub-pixel array 110_1a are associated differently with different color filters (i.e., configured functionally with different color filters), such as a red filter (R), a green filter (G), a blue filter (B), and a white filter (W) or a yellow filter (Y). Here, it is assumed that the first sub-pixel array 110_1a includes a first pixel group, a second pixel group, a third pixel group, and a fourth pixel group PG1a to PG4a.

[0075] exist Figure 4A In this model, both the first pixel group PG1a and the fourth pixel group PG4a have horizontal pixels PX_X that are associated with the green filter (G) and the white filter (W) differently. Specifically, the seventh sub-pixel SPX17 and the eighth sub-pixel SPX18 of the first pixel group PG1a are associated with the white filter (W), and the first sub-pixel SPX41 and the second sub-pixel SPX42 of the fourth pixel group PG4a are associated with the white filter (W). Alternatively, the horizontal pixels PX_X of the first pixel group PG1a and the fourth pixel group PG4a can be associated with the green filter (G) and the yellow filter (Y).

[0076] Similarly, the horizontal pixel PX_X of the second pixel group PG2a is associated differently with the red filter (R) and the white filter (W). That is, the fifth sub-pixel SPX25 and the sixth sub-pixel SPX26 of the second pixel group PG2a are associated with either the white filter (W) or the yellow filter (Y). The horizontal pixel PX_X of the third pixel group PG3a is associated differently with the blue filter (B) and the white filter (W). That is, the third sub-pixel SPX33 and the fourth sub-pixel SPX34 of the third pixel group PG3a are associated with either the white filter (W) or the yellow filter (Y).

[0077] Therefore, as Figure 4A As shown, some embodiments of the present invention may associate adjacent horizontal pixels PX_X selected from different pixel groups with color filters, while unselected horizontal pixels PX_X from each pixel group in different pixel groups may be associated with different color filters.

[0078] In comparison, such as Figure 4B As shown, each pixel group (e.g., the first to fourth pixel groups PG1b to PG4b) can be associated with a color filter in the color filter set. For example, the first pixel group PG1b is associated with the green color filter (G), the second pixel group PG2b is associated with the red color filter (R), the third pixel group PG3b is associated with the blue color filter (B), and the fourth pixel group PG4b is associated with either the white color filter (W) or the yellow color filter (Y).

[0079] In further comparisons, such as Figure 4C As shown, each individual horizontal pixel PX_X can be associated with a selected color filter from the filter set, regardless of whether the individual horizontal pixel PX_X is included in a particular pixel group. Therefore, the first to fourth pixel groups PG1c to PG4c all include color filters with different colors.

[0080] like Figure 4CAs shown, the first pixel group PG1c and the fourth pixel group PG4c include a green filter (G) and a white filter (W) or a yellow filter (Y). The first sub-pixel SPX11, the second sub-pixel SPX12, the seventh sub-pixel SPX17, and the eighth sub-pixel SPX18 of the first pixel group PG1c are associated with the white filter (W) or the yellow filter (Y), while the first sub-pixel SPX41, the second sub-pixel SPX42, the seventh sub-pixel SPX47, and the eighth sub-pixel SPX48 of the fourth pixel group PG4c are associated with the white filter (W) or the yellow filter (Y). Furthermore, the third sub-pixel SPX13, the fourth sub-pixel SPX14, the fifth sub-pixel SPX15, and the sixth sub-pixel SPX16 of the first pixel group PG1c are associated with the green filter (G), while the third sub-pixel SPX43, the fourth sub-pixel SPX44, the fifth sub-pixel SPX45, and the sixth sub-pixel SPX46 of the fourth pixel group PG4c are associated with the green filter (G).

[0081] The second pixel group PG2c includes horizontal pixels PX_X that are associated differently from the red filter (R) and the white filter (W) or yellow filter (Y). Therefore, the first sub-pixel SPX21, the second sub-pixel SPX22, the seventh sub-pixel SPX27, and the eighth sub-pixel SPX28 of the second pixel group PG2c are all associated with the white filter (W) or the yellow filter (Y), while the third sub-pixel SPX23, the fourth sub-pixel SPX24, the fifth sub-pixel SPX25, and the sixth sub-pixel SPX26 of the second pixel group PG2c are associated with the red filter (R).

[0082] The third pixel group PG3c includes horizontal pixels PX_X that are associated differently from the blue filter (B) and the white filter (W) or the yellow filter (Y). Therefore, the first sub-pixel SPX31, the second sub-pixel SPX32, the seventh sub-pixel SPX37, and the eighth sub-pixel SPX38 of the third pixel group PG3c are associated with the white filter (W) or the yellow filter (Y), while the third sub-pixel SPX33, the fourth sub-pixel SPX34, the fifth sub-pixel SPX35, and the sixth sub-pixel SPX36 of the third pixel group PG3c are all associated with the blue filter (B).

[0083] Figure 5 This is a circuit diagram illustrating the arrangement of the first and second sub-pixels of a shared floating diffusion region according to certain embodiments of the present invention. Figure 5 In this design, the first and second sub-pixels of a pixel (e.g., a horizontal or vertical pixel) are configured within a shared pixel structure to share a floating diffusion region. However, other embodiments of the inventive concept may include other arrangements of various sub-pixels sharing the floating diffusion region.

[0084] exist Figure 5 In this configuration, the first sub-pixel includes a first photodiode PD11, a first transmission transistor TX11, a selection transistor SX1, a drive transistor SF1, and a reset transistor RX1. The second sub-pixel includes a second photodiode PD12, a second transmission transistor TX12, a selection transistor SX1, a drive transistor SF1, and a reset transistor RX1. Using this configuration (e.g., a shared pixel structure SHPX), the first and second sub-pixels can effectively share the floating diffusion region FD1, as well as the selection transistor SX1, drive transistor SF1, and reset transistor RX1. Those skilled in the art will recognize that in other configurations, one or more of the selection transistor SX1, drive transistor SF1, and reset transistor RX1 may be omitted.

[0085] Here, both the first photodiode PD11 and the second photodiode PD12 can generate photoelectric charge based on the received incident light. For example, both the first photodiode PD11 and the second photodiode PD12 can be PN junction diodes that generate photoelectric charge (i.e., electrons as negative photoelectric charge and holes as positive photoelectric charge) in proportion to the amount of incident light. That is, both the first photodiode PD11 and the second photodiode PD12 can include at least one photoelectric conversion element such as a phototransistor, a photogate, or a pinned photodiode (PPD).

[0086] The first transmission transistor TX11 can be used to transfer the photoelectric charge generated by the first photodiode PD11 to the floating diffusion region FD1 in response to the first transmission control signal TS11 applied to the first transmission transistor TX11. Therefore, when the first transmission transistor TX11 is turned on, the photoelectric charge generated by the first photodiode PD11 is transferred to the floating diffusion region FD1, where the photoelectric charge is accumulated (or stored) in the floating diffusion region FD1. Similarly, when the second transmission transistor TX12 is turned on in response to the second transmission control signal TS12, the photoelectric charge generated by the second photodiode PD12 is transferred to the floating diffusion region FD1 and accumulated in the floating diffusion region FD1.

[0087] In this regard, the floating diffusion region FD1 serves as a photoelectric charge capacitor. Therefore, in some embodiments of the present invention, as the number of photodiodes operatively connected to the floating diffusion region FD1 increases, the capacitance storage capacity of the floating diffusion region FD1 must also increase.

[0088] The reset transistor RX1 can be used to periodically reset the photoelectric charge accumulated in the floating diffusion region FD1. The source electrode of the reset transistor RX can be connected to the floating diffusion region FD1, and its drain electrode can be connected to the source voltage VPIX. When the reset transistor RX is turned on in response to the reset control signal RS1, the source voltage VPIX connected to the drain electrode of the reset transistor RX1 can be applied to the floating diffusion region FD1. When the reset transistor RX1 is turned on, the photoelectric charge accumulated in the floating diffusion region FD1 can be released, thus resetting the floating diffusion region FD1.

[0089] The driving transistor SF1 can be controlled based on the amount of photocharge accumulated in the floating diffusion region FD1. The driving transistor SF1 can be a buffer amplifier and can buffer the signal in response to the photocharge accumulated in the floating diffusion region FD1. The driving transistor SF1 can amplify the changing potential in the floating diffusion region FD1 and output the amplified potential as the pixel signal VOUT to the column output line (e.g., ...). Figure 2 (One of the first column output line CLO_0 to the (n-1)th column output line CLO_n-1).

[0090] The drain terminal of the select transistor SX1 can be connected to the source terminal of the drive transistor SF1, and in response to the select signal SELS1, the select transistor SX1 can output the pixel signal VOUT to the CDS (e.g., ...) via the corresponding column output lines. Figure 2 CDS 151).

[0091] According to embodiments of the present invention, such as Figure 5 One or more of the first transmission control signal TS11, the second transmission control signal TS12, the reset control signal RS1, and the selection signal SELS1 shown may be determined relative to the pixel array (e.g., Figure 2 The row driver (e.g., the pixel array 110) operates on. Figure 2 The control signals provided by the line driver 140.

[0092] Figure 6A , Figure 6B , Figure 6C , Figure 6D and Figure 6E These are individual diagrams illustrating the sub-pixel arrangement of a shared floating diffusion region. Such a sub-pixel arrangement can be included in the sub-pixel array of the pixel array included in embodiments of the present invention (e.g., Figure 3A The first sub-pixel array 110_1 Figure 3B The second sub-pixel array 110_2 and Figures 4A to 4C (one or more sub-pixel arrays).

[0093] Reference Figure 6A The first subpixel array 100_1e may include first to fourth pixel groups PG1e to PG4e, and each of the first to fourth pixel groups PG1e to PG4e may include multiple horizontal pixels PX_X. The subpixels included in each horizontal pixel PX_X can be configured in a shared pixel structure SHPX1 that shares different floating diffusion areas. That is, the shared pixel structure SHPX1 can be a 2-shared structure including two subpixels. Therefore, the two subpixels will share a single floating diffusion area.

[0094] For example, the first sub-pixel SPX11 and the second sub-pixel SPX12 of the first pixel group PG1e can be configured in a shared pixel structure SHPX1 that shares a first floating diffusion area, while the third sub-pixel SPX13 and the fourth sub-pixel SPX14 of the first pixel group PG1e can be configured in a shared pixel structure SHPX1 that shares a floating diffusion area different from the first floating diffusion area. In this case, the first sub-pixel SPX11 and the third sub-pixel SPX13 are associated with different floating diffusion areas.

[0095] The foregoing description of the first pixel group PG1e can be applied to the second to fourth pixel groups PG2e to PG4e.

[0096] In high-resolution mode, the first sub-pixel array 100_1e can accumulate all photoelectric charges generated by at least two (2) photodiodes of different sub-pixels in the floating diffusion region. For example, the first sub-pixel array 100_1e can output a reset voltage as a pixel signal (e.g., Figure 5 Then, a pixel signal VOUT based on the first sub-pixel SPX11 can be output, and then a pixel signal VOUT based on the first sub-pixel SPX11 and the second sub-pixel SPX12 can be output. That is, sub-pixels configured together in a single horizontal pixel (e.g., the first sub-pixel SPX11 and the second sub-pixel SPX12) can share a floating diffusion area (e.g., Figure 5 The floating diffusion region FD1), and therefore can be based on the first photodiode of the first sub-pixel SPX11 (e.g., Figure 5 The photoelectric charge generated by the first photodiode PD11 and the photoelectric charge generated by the second photodiode of the second sub-pixel SPX12 (e.g., Figure 5 The second photodiode PD12 generates photoelectric charge to output the pixel signal VOUT. This readout method can be the reset-signal-signal-reset-signal-signal-reset-signal-signal-reset-signal (RSSRSSRSSRSS) readout method.

[0097] However, the operation of the image sensor including the first sub-pixel array 100_1e in high-resolution mode according to the embodiment is not limited thereto. Although the first sub-pixel SPX11 and the second sub-pixel SPX12 share the floating diffusion region FD1, the first sub-pixel array 100_1e can output a pixel signal VOUT based on the first sub-pixel SPX11, then reset the floating diffusion region FD1 to output a reset voltage as the pixel signal VOUT, and then output a pixel signal VOUT based on the second sub-pixel SPX12. Such a readout method can be a reset-signal-reset-signal-reset-signal-reset-signal-reset-signal-reset-signal-signal (RSRSRSRSRSRSRSRS) readout method.

[0098] Therefore, when obtaining the pixel signal VOUT output from each sub-pixel included in a shared pixel structure SHPX1 that shares a floating diffusion region, the image sensor consistent with the embodiments of the present invention can adjust the number of floating diffusion region resets differently. As the number of floating diffusion region resets increases, the time spent obtaining the pixel signal VOUT output from each sub-pixel included in a shared pixel structure SHPX1 also increases, but a floating diffusion region with relatively low capacitance can be formed, and the conversion gain can be increased. On the other hand, as the number of floating diffusion region resets decreases, a floating diffusion region with high capacitance is required. However, the time spent obtaining the pixel signal VOUT output from each sub-pixel included in a shared pixel structure SHPX1 can be reduced.

[0099] In some embodiments of the present invention, the first to fourth pixel groups PG1e to PG4e of the first sub-pixel array 100_1e can be connected to different column output lines (e.g., the corresponding column output lines in the first column output line CLO_0 to the (n-1)th column output line CLO_n-1). For example, multiple pixels PX_X of the first pixel group PG1e can be connected to the first column output line CLO_0, multiple pixels PX_X of the second pixel group PG2e can be connected to the second column output line CLO_1, multiple pixels PX_X of the third pixel group PG3e can be connected to the third column output line CLO_2, and multiple pixels PX_X of the fourth pixel group PG4e can be connected to the fourth column output line CLO_3.

[0100] In this configuration, the image sensor including the first sub-pixel array 100_1e can perform analog pixel binning in low-resolution mode. Specifically, in low-resolution mode, the first sub-pixel array 100_1e can output a reset voltage as a pixel signal VOUT via the first column output line CLO_0. Subsequently, it outputs pixel signals VOUT based on the first sub-pixel SPX11, third sub-pixel SPX13, fifth sub-pixel SPX15, and seventh sub-pixel SPX17 via the first column output line CLO_0, and then outputs pixel signals VOUT based on the first to eighth sub-pixels SPX11 to SPX18 via the first column output line CLO_0. This readout method can be a reset-signal-signal (RSS) readout method.

[0101] Alternatively, in low-resolution mode, the first sub-pixel array 100_1e can output a reset voltage as a pixel signal VOUT via the first column output line CLO_0. Subsequently, it can output pixel signals VOUT based on the first sub-pixel SPX11, third sub-pixel SPX13, fifth sub-pixel SPX15, and seventh sub-pixel SPX17 via the first column output line CLO_0. Then, it can output a reset voltage as a pixel signal VOUT again via the first column output line CLO_0, and subsequently, it can output pixel signals VOUT based on the second sub-pixel SPX12, fourth sub-pixel SPX14, sixth sub-pixel SPX16, and eighth sub-pixel SPX18 via the first column output line CLO_0. This readout method can be a reset-signal-reset-signal (RS-RS) readout method.

[0102] However, the image sensor according to the embodiment of the present invention is not limited thereto, and the plurality of horizontal pixels PX_X included in the first sub-pixel array 100_1e can be respectively connected to different column output lines. In this case, the image sensor including the first sub-pixel array 100_1e can perform digital pixel binning operation in low-resolution mode. For example, in low-resolution mode, the first sub-pixel array 100_1e can output different pixel signals VOUT based on the first sub-pixel SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17 through different column output lines, and each pixel signal VOUT can be generated by a CDS (e.g., Figure 2 151) and ADC (e.g., Figure 2 The 153) is converted into a digital signal and can be stored in a buffer (e.g., Figure 2 In buffer 155), the data corresponding to the pixel signal output from each of the first sub-pixels SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17 can be output as a signal to the signal processor (e.g., 155). Figure 2 The buffer 155 can then output data corresponding to the pixel signals output from each of the second sub-pixels SPX12, the fourth sub-pixel SPX14, the sixth sub-pixel SPX16, and the eighth sub-pixel SPX18 as a single signal to the signal processor 130 or the external image sensor.

[0103] Based on the foregoing, those skilled in the art will recognize that the image sensor according to embodiments of the present invention may include a subpixel array (e.g., Figure 6A The first sub-pixel array 100_1e) can perform AF function on a pixel-by-pixel basis in high-resolution mode, or on a pixel-by-pixel basis in low-resolution mode.

[0104] In other embodiments of the inventive concept that can operate in a medium resolution mode, the image sensor including the first subpixel array 100_1e can perform analog pixel binning or digital pixel binning. Therefore, the image sensor including the first subpixel array 100_1e can perform AF functionality on a pixel-by-pixel basis in high resolution mode and on a pixel-by-pixel basis in low resolution mode. In this way, the image sensor according to embodiments of the inventive concept can effectively operate in high resolution, low resolution, and medium resolution modes to appropriately meet the needs of the lighting environment.

[0105] Reference Figure 6B The first sub-pixel array 100_1f includes first to fourth pixel groups PG1f to PG4f, wherein each of the first to fourth pixel groups PG1f to PG4f includes multiple horizontal pixels PX_X. Adjacent horizontal pixels PX_X (in the X direction) among the multiple horizontal pixels PX_X can be configured in a shared pixel structure SHPX2X to share a single floating diffusion area. That is, Figure 6B The shared pixel structure SHPX2X can be a 4-shared structure that includes four sub-pixels sharing a single floating diffuse area.

[0106] The image sensor including the first sub-pixel array 100_1f can perform AF function on a pixel-by-pixel basis in high-resolution mode, and can perform AF function on a pixel-by-pixel basis in low-resolution mode in combination with the first to fourth pixel groups PG1f to PG4f. For example, in high-resolution mode, the first sub-pixel array 100_1f can output the pixel signal VOUT according to the RSSRSSRSSRSS readout method described above. Alternatively, the first sub-pixel array 100_1f can output the pixel signal VOUT according to the RSSRSSRSRSRSRSRS readout method described above.

[0107] Alternatively, in high-resolution mode, the first sub-pixel array 100_1f can accumulate all the photoelectric charge generated by four different photodiodes into a floating diffusion region. For example, the first sub-pixel array 100_1f can output a reset voltage as a pixel signal VOUT, and then output pixel signals VOUT based on the first sub-pixel SPX11, the second sub-pixel SPX12, the first to third sub-pixels SPX11 to SPX13, and the first to fourth sub-pixels SPX11 to SPX14. Such a readout method can be a reset-signal-signal-signal-signal-reset-signal-signal-signal (RSSSSRSSSS) readout method.

[0108] Alternatively, for example, in high-resolution mode, the first sub-pixel array 100_1f can output a reset voltage as a pixel signal VOUT, and then output pixel signals VOUT based on the first sub-pixel SPX11, the second sub-pixel SPX12, and the fourth sub-pixel SPX11 to SPX14. That is, in high-resolution mode, the first sub-pixel array 100_1f can simultaneously accumulate the photoelectric charge generated by the photodiodes of the third sub-pixel SPX13 and the fourth sub-pixel SPX14 into a floating diffusion region. Such a readout method can be a reset-signal-signal-signal-reset-signal-signal-signal (RSSSRSSS) readout method. In this case, the third sub-pixel SPX13 and the fourth sub-pixel SPX14 may not be used for AF function, but the overall readout speed of the first sub-pixel array 100_1f can be increased.

[0109] On the other hand, the image sensor including the first sub-pixel array 100_1f can perform analog pixel binning operations in low-resolution mode. For example, the first sub-pixel array 100_1f can output pixel signals VOUT based on the first, third, fifth, and seventh sub-pixels SPX11, SPX13, SPX15, and SPX17 to the first column output line CLO_0, and can then output pixel signals VOUT based on the first to eighth sub-pixels SPX11 to SPX18 to the first column output line CLO_0. Alternatively, for example, the first sub-pixel array 100_1f can output the pixel signal VOUT based on the first sub-pixel SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17 to the first column output line CLO_0, and then output the reset voltage as the pixel signal VOUT to the first column output line CLO_0 again, and then output the pixel signal VOUT based on the second sub-pixel SPX12, the fourth sub-pixel SPX14, the sixth sub-pixel SPX16, and the eighth sub-pixel SPX18 to the first column output line CLO_0.

[0110] On the other hand, the first sub-pixel array 100_1f can perform digital pixel binning operations in low-resolution mode. For example, the first sub-pixel array 100_1f can output pixel signals VOUT based on the first sub-pixel SPX11 and the third sub-pixel SPX13, as well as pixel signals VOUT based on the fifth sub-pixel SPX15 and the seventh sub-pixel SPX17, to different column output lines, and each pixel signal VOUT can be generated by a CDS (e.g., Figure 2 151) and ADC (e.g., Figure 2 The 153) is converted into a digital signal and can be stored in a buffer (e.g., Figure 2 In buffer 155), the data corresponding to the pixel signal output from each of the first sub-pixels SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17 can be output as a signal to the signal processor (e.g., 155). Figure 2The buffer 155 can then output data corresponding to the pixel signals output from each of the sub-pixels in the second sub-pixel SPX12, the fourth sub-pixel SPX14, the sixth sub-pixel SPX16, and the eighth sub-pixel SPX18 as a single signal to the signal processor 130 or the external image sensor. Therefore, the image sensor including the first sub-pixel array 100_1f can perform AF on a pixel-by-pixel basis in high-resolution mode and on a pixel-by-pixel basis in low-resolution mode. The first sub-pixel array 100_1g can include first to fourth pixel groups PG1g to PG4g, and each of the first to fourth pixel groups PG1g to PG4g can include multiple horizontal pixels PX_X. Adjacent horizontal pixels PX_X (in the Y direction) among the multiple horizontal pixels PX_X can be configured in a shared pixel structure SHPX2Y sharing a single floating diffusion region. That is, the shared pixel structure SHPX2Y can be a 4-shared structure including four sub-pixels, and four sub-pixels can be configured each time in the shared pixel structure SHPX2Y with a shared floating diffusion area. In each of the high-resolution mode and the low-resolution mode, the description of the operation of the first sub-pixel array 100_1f described above can be similarly applied to the operation of the first sub-pixel array 100_1g.

[0111] Reference Figure 6C The first sub-pixel array 100_1h includes first to fourth pixel groups PG1h to PG4h, wherein each of the first to fourth pixel groups PG1h to PG4h includes multiple horizontal pixels PX_X. The horizontal pixels PX_X within the same specific group are configured in a shared pixel structure SHPX3 sharing a floating diffusion area. That is, the shared pixel structure SHPX3 can be an 8-shared structure including eight sub-pixels, and each set of eight sub-pixels can be configured with a shared pixel structure SHPX3 sharing a floating diffusion area. Therefore, sub-pixels included in different pixel groups may not share a floating diffusion area. The following will refer to... Figures 9 to 11 Describe the operation of the first subpixel array 100_1h in high resolution mode and the operation of the first subpixel array 100_1h in low resolution mode.

[0112] Reference Figure 6DThe first sub-pixel array 100_1i includes first to fourth pixel groups PG1i to PG4i, wherein each of the first to fourth pixel groups PG1i to PG4i includes multiple horizontal pixels PX_X. (In the X direction) Adjacent horizontal pixels PX_X can be configured in a shared pixel structure SHPX4X sharing a single floating diffusion area. That is, the shared pixel structure SHPX4X can be a 16-shared structure including sixteen sub-pixels, and each set of sixteen sub-pixels can be configured to share a floating diffusion area in the shared pixel structure SHPX4X.

[0113] For example, the first to eighth sub-pixels SPX11 to SPX18 of the first pixel group PG1i and the first to eighth sub-pixels SPX21 to SPX28 of the second pixel group PG2i can be configured with a shared pixel structure SHPX4X that shares a floating diffusion area, and the first to eighth sub-pixels SPX31 to SPX38 of the third pixel group PG3i and the first to eighth sub-pixels SPX41 to SPX48 of the fourth pixel group PG4i can also be configured with a shared pixel structure SHPX4X that shares a floating diffusion area. Therefore, sub-pixels included in different pixel groups can share a floating diffusion area.

[0114] The first sub-pixel array 100_1j includes first to fourth pixel groups PG1j to PG4j, wherein each of the first to fourth pixel groups PG1j to PG4j includes multiple horizontal pixels PX_X. (In the Y direction) Adjacent horizontal pixels PX_X can be configured in a shared pixel structure SHPX4Y sharing a single floating diffusion area. That is, the shared pixel structure SHPX4Y can be a 16-shared structure including sixteen sub-pixels, and each set of sixteen sub-pixels can be configured to share a floating diffusion area within the shared pixel structure SHPX4Y.

[0115] For example, the first to eighth sub-pixels SPX11 to SPX18 of the first pixel group PG1j and the first to eighth sub-pixels SPX31 to SPX38 of the third pixel group PG3j can be configured with a shared pixel structure SHPX4Y that shares a floating diffusion area. Similarly, the first to eighth sub-pixels SPX21 to SPX28 of the second pixel group PG2j and the first to eighth sub-pixels SPX41 to SPX48 of the fourth pixel group PG4j can be configured with a shared pixel structure SHPX4Y that shares a floating diffusion area. Therefore, sub-pixels included in different pixel groups can share a floating diffusion area.

[0116] right Figure 6C The description of the first sub-pixel array 100_1h in high-resolution mode can be similarly applied to the operation of each of the first sub-pixel arrays 100_1i and 100_1j in high-resolution mode. Figure 6CThe description of the first subpixel array 100_1h in low-resolution mode can be similarly applied to the operation of each of the first subpixel arrays 100_1i and 100_1j in low-resolution mode.

[0117] Reference Figure 6E The first sub-pixel array 100_1k includes first to fourth pixel groups PG1k to PG4k, wherein each of the first to fourth pixel groups PG1k to PG4k includes multiple horizontal pixels PX_X. The horizontal pixels PX_X included in the first to fourth pixel groups PG1k to PG4k can be configured in a shared pixel structure SHPX5 sharing a single floating diffusion area. That is, the shared pixel structure SHPX5 can be a 32-shared structure including 32 sub-pixels, and each time 32 sub-pixels can be configured to share a floating diffusion area in the shared pixel structure SHPX5. Figure 6C The description of the first sub-pixel array 100_1h in high-resolution mode can be similarly applied to the operation of the first sub-pixel array 100_1k in high-resolution mode. Figure 6C The description of the first subpixel array 100_1h in low-resolution mode can be similarly applied to the operation of the first subpixel array 100_1k in low-resolution mode.

[0118] exist Figure 6A , Figure 6B , Figure 6C , Figure 6D and Figure 6E In the illustrated embodiments, specific details of the shared pixel structures SHPX1, SHPX2, SHPX3, SHPX4, and SHPX5 respectively disposed in the first sub-pixel arrays 110_1e, 110_1f, 110_1g, 110_1h, 110_1i, 110_1j, and 110_1k have been described above. However, the image sensor according to embodiments of the present invention is not limited thereto, and various sub-pixel array structures can be implemented in various ways.

[0119] Figure 7 This is a circuit diagram further illustrating the arrangement of sub-pixels sharing a shared floating diffusion region in one embodiment. Figure 7 In this architecture, the shared pixel structure provides dual conversion gain (DCG) functionality. Assuming... Figure 7 The shared pixel structure includes four photodiodes sharing the first floating diffusion region HCG_FD_A and four photodiodes sharing the second floating diffusion region HCG_FD_B.

[0120] Reference Figure 7The shared pixel structure SHPX' includes first to eighth photodiodes PD11 to PD18, first to eighth transmission transistors TX11 to TX18, first and second selection transistors SX1 and SX2, first and second drive transistors SF1 and SF2, and first to fourth reset transistors RX11, RX21, RX12 and RX22.

[0121] The first to fourth transmission transistors TX11 to TX14 can respectively respond to their corresponding first to fourth transmission control signals TS11 to TS14 to connect the first to fourth photodiodes PD11 to PD14 to the first floating diffusion region HCG_FD_A. The fifth to eighth transmission transistors TX15 to TX18 can respectively respond to their corresponding fifth to eighth transmission control signals TS15 to TS18 to connect the fifth to eighth photodiodes PD15 to PD18 to the second floating diffusion region HCG_FD_B. For example, sub-pixels including the first to fourth photodiodes PD11 to PD14 can share the first floating diffusion region HCG_FD_A, and sub-pixels including the fifth to eighth photodiodes PD15 to PD18 can share the second floating diffusion region HCG_FD_B.

[0122] The first reset transistor RX11 and the second reset transistor RX21 can periodically reset the photoelectric charge accumulated in the first floating diffusion region HCG_FD_A in response to the first reset control signal RS11 and the second reset control signal RS21. The source electrode of the first reset transistor RX11 can be connected to the first floating diffusion region HCG_FD_A, and its drain electrode can be connected to the second reset transistor RX21 and the third floating diffusion region LCG_FD. The source electrode of the second reset transistor RX21 can be connected to the first reset transistor RX11 and the third floating diffusion region LCG_FD, and its drain electrode can be connected to the source voltage VPIX.

[0123] The third reset transistor RX12 and the fourth reset transistor RX22 can periodically reset the photoelectric charge accumulated in the second floating diffusion region HCG_FD_B in response to the third reset control signal RS12 and the fourth reset control signal RS22. The source electrode of the third reset transistor RX12 can be connected to the second floating diffusion region HCG_FD_B, and its drain electrode can be connected to the fourth reset transistor RX22 and the third floating diffusion region LCG_FD. The source electrode of the fourth reset transistor RX22 can be connected to the third reset transistor RX12 and the third floating diffusion region LCG_FD, and its drain electrode can be connected to the source voltage VPIX.

[0124] When the first reset transistor RX11 is turned on, the first floating diffusion region HCG_FD_A can be connected to the third floating diffusion region LCG_FD. Furthermore, when the third reset transistor RX12 is turned on, the second floating diffusion region HCG_FD_B can be connected to the third floating diffusion region LCG_FD. Therefore, when both the first reset transistor RX11 and the third reset transistor RX12 are turned on, the first floating diffusion region HCG_FD_A, the second floating diffusion region HCG_FD_B, and the third floating diffusion region LCG_FD can be connected to each other. Thus, the shared pixel structure of the image sensor according to the embodiment can be... Figure 6B The shared pixel structures SHPX2X and SHPX2Y with 4-shared structure become Figure 6C The SHPX3 shared pixel structure with an 8-shared structure.

[0125] The first selection transistor SX1 and the second selection transistor SX2 can respond to the first selection signal SELS1 and the second selection signal SELS2, and output the pixel signal VOUT to the CDS (e.g., ) via the column output line. Figure 2 (151).

[0126] In the image sensor according to an embodiment of the present invention, as the capacitance of the floating diffusion region decreases / increases, the conversion gain will increase / decrease accordingly. Therefore, as the capacitance of the floating diffusion region increases, relatively more photoelectric charge accumulates in the floating diffusion region. Consequently, the number of reset operations that must be performed is reduced, thereby improving the overall operating speed. Therefore, depending on the situation, the pixel array can operate in a 4-shared structure in high conversion gain (HCG) mode and in an 8-shared structure in low conversion gain (LCG) mode, thereby supporting dual conversion gain (DCG) functionality.

[0127] Figure 8 , Figure 9 , Figure 10 and Figure 11 These are timing diagrams further illustrating the operation of an image sensor according to an embodiment of the concept of the present invention. In the timing diagrams, for ease of description, it is assumed that the image sensor described with reference to the first sub-pixel array 100_1h includes... Figure 6C The shared pixel structure SHPX3 is shown.

[0128] In one embodiment, refer to Figure 8 and Figure 9 The operation of the image sensor is described. It is further assumed that the plurality of horizontal pixels PX_X included in the first sub-pixel array 100_1h provide pixel signals for AF functionality in high-resolution mode. In another embodiment, reference is made to... Figure 10The operation of the image sensor is described. Here, it is again assumed that the plurality of horizontal pixels PX_X included in the first sub-pixel array 100_1h provide pixel signals for AF functionality in high-resolution mode. In yet another embodiment, reference is made below. Figure 11 The described operation of the image sensor can be an embodiment of outputting pixel signals for AF function in a low-resolution mode.

[0129] Common Reference Figure 5 , Figure 6C and Figure 8 In the first sub-pixel SPX11, in response to the switching operation of the first transmission transistor TX11 controlled by the first transmission control signal TS11, photoelectric charge generated by the first photodiode PD11 accumulates in the floating diffusion region FD1. In the second sub-pixel SPX12, in response to the switching operation of the second transmission transistor TX12 controlled by the second transmission control signal TS12, photoelectric charge generated by the second photodiode PD12 accumulates in the floating diffusion region FD1. In the seventh sub-pixel SPX17, in response to the switching operation of the seventh transmission transistor controlled by the seventh transmission control signal TS17, photoelectric charge generated by the seventh photodiode accumulates in the floating diffusion region FD1. In the eighth sub-pixel SPX18, in response to the switching operation of the eighth transmission transistor controlled by the eighth transmission control signal TS18, photoelectric charge generated by the eighth photodiode accumulates in the floating diffusion region FD1.

[0130] The first pixel group PG1h can be reset, and then the first to eighth transmission transistors of the first to eighth sub-pixels SPX11 to SPX18 can be sequentially turned on. That is, the reset control signal RS1 can be changed from logic high level to logic low level, and then the first to eighth transmission control signals TS11 to TS18 can be sequentially changed from logic low level to logic high level.

[0131] By ramp signal generator (e.g., Figure 2 The ramp signal generator 157) generates a ramp voltage RMP that comprises nine pulses during the time interval between the reset control signal RS1 transitioning from logic high to logic low and then back to logic high. Each pulse can have a triangular waveform that decreases and then increases sequentially. For example... Figure 8 As shown, the pulse amplitude can gradually increase with each activation, but this signaling method is just an example.

[0132] Therefore, when resetting the floating diffusion region FD1 of the first pixel group PG1h, the first pulse R can be a pulse corresponding to the pixel voltage VOUT. The signal level of the reset voltage change will be relatively low.

[0133] The second pulse S1 can be a pulse corresponding to the pixel signal VOUT based on the photoelectric charge generated by the first photodiode PD11 of the first sub-pixel SPX11. In the pixel signal VOUT, a voltage drop can be added to the reset voltage, so the second pulse S1 can be adjusted to drop lower than the first pulse R and then be restored.

[0134] The third pulse S1S2 can be a pixel signal VOUT based on the photoelectric charge generated by the first photodiode PD11 of the first sub-pixel SPX11 and the second photodiode PD12 of the second sub-pixel SPX12. The fourth pulse S1...S7 can be a pixel signal VOUT based on the photoelectric charge generated by the first to seventh photodiodes of the first to seventh sub-pixels SPX11 to SPX17, and the fifth pulse S1...S8 can be a pixel signal VOUT based on the photoelectric charge generated by the first to eighth photodiodes of the first to eighth sub-pixels SPX11 to SPX18.

[0135] As described above, the waveform of the ramp voltage RMP can be derived from the pixel signal VOUT output from the first pixel group PGLH. That is, the first pixel group PG1h can first output a reset voltage as the pixel signal VOUT, and then output pixel signals VOUT based on the first sub-pixel SPX11, the second sub-pixel SPX12, the first to third sub-pixels SPX11 to SPX13, the first to fourth sub-pixels SPX11 to SPX14, the first to fifth sub-pixels SPX11 to SPX15, the first to sixth sub-pixels SPX11 to SPX16, the first to seventh sub-pixels SPX11 to SPX17, and the first to eighth sub-pixels SPX11 to SPX18. Such a readout method can be the reset-signal-signal-signal-signal-signal-signal-signal-signal (RSSSSSSSS) readout method.

[0136] The photoelectric charges generated by the first to eighth sub-pixels SPX11 to SPX18 included in the first pixel group PGLH can be sequentially accumulated in the floating diffusion region FD1, and the pixel signal VOUT based thereon can be sequentially output. After performing a reset operation on the first pixel group PG1h, the pixel signal VOUT corresponding to the photoelectric charges generated by the first to eighth sub-pixels SPX11 to SPX18 can be sequentially output, thus the image sensor according to this disclosure can perform high-speed operation. Therefore, when high-speed operation such as in motion picture mode is required, the number of reset operations can be reduced, and the photoelectric charges generated by the first to eighth sub-pixels SPX11 to SPX18 can be sequentially accumulated in the floating diffusion region FD1.

[0137] Furthermore, the first to eighth transmission transistors of the first to eighth sub-pixels SPX11 to SPX18 can be sequentially turned on (i.e., Figure 8 As shown in the diagram, TS11_on to TS18_on, and the pixel signal VOUT corresponding to the photoelectric charge generated by the first to eighth sub-pixels SPX11 to SPX18, can be output sequentially, thereby providing a high-resolution mode that allows AF function to be performed on a pixel-by-pixel basis. At this time, multiple pixels PX_X included in the first pixel group PG1h can all output pixel signals VOUT including AF information.

[0138] Common Reference Figure 5 , Figure 6C and Figure 9 The first to eighth transmission transistors of the first to eighth sub-pixels SPX11 to SPX18 can be turned on sequentially. That is, the first to eighth transmission control signals TS11 to TS18 can be sequentially changed from logic low level to logic high level.

[0139] The first pulse R1 of the ramp voltage RMP can be a pulse corresponding to the pixel voltage VOUT when the floating diffusion region FD1 of the first pixel group PG1h is reset. The second pulse S1 can be a pulse corresponding to the pixel signal VOUT based on the photoelectric charge generated by the first photodiode PD11 of the first sub-pixel SPX11. The third pulse S1S2 can be pulses corresponding to the pixel signal VOUT based on the photoelectric charge generated by the first photodiode PD11 of the first sub-pixel SPX11 and the second photodiode PD12 of the second sub-pixel SPX12.

[0140] The fourth pulse R4 can be the pixel voltage VOUT when the floating diffusion region FD1 of the first pixel group PG1h is reset. The fifth pulse S7 can be the pixel signal VOUT based on the photoelectric charge generated by the seventh photodiode of the seventh sub-pixel SPX17. The sixth pulses S7S8 can be the pixel signal VOUT based on the photoelectric charge generated by the seventh photodiode of the seventh sub-pixel SPX17 and the eighth photodiode of the eighth sub-pixel SPX18.

[0141] The first pixel group PG1h can first output a reset voltage as the pixel signal VOUT, then output a pixel signal VOUT based on the first sub-pixel SPX11, and also output pixel signals VOUT based on the first sub-pixel SPX11 and the second sub-pixel SPX12. Subsequently, the first pixel group PG1h can first output a reset voltage as the pixel signal VOUT, then output a pixel signal VOUT based on the third sub-pixel SPX13, and also output pixel signals VOUT based on the third sub-pixel SPX13 and the fourth sub-pixel SPX14. Subsequently, the first pixel group PG1h can output a reset voltage as the pixel signal VOUT, then output a pixel signal VOUT based on the fifth sub-pixel SPX15, and also output pixel signals VOUT based on the fifth sub-pixel SPX15 and the sixth sub-pixel SPX16. Subsequently, the first pixel group PG1h can output a reset voltage as the pixel signal VOUT, then output a pixel signal VOUT based on the seventh sub-pixel SPX17, and also output pixel signals VOUT based on the seventh sub-pixel SPX17 and the eighth sub-pixel SPX18. This reading method can be referenced above. Figure 6B The described RSSRSS RSSRSS readout method.

[0142] The photoelectric charge generated by some sub-pixels (e.g., selected sub-pixels) of the first to eighth sub-pixels SPX11 to SPX18 included in the first pixel group PG1h accumulates in the floating diffusion region FD1, and after the floating diffusion region FD1 is reset, the photoelectric charge generated by other sub-pixels accumulates again in the floating diffusion region FD1. Therefore, even when the capacitance of the floating diffusion region FD1 is low, the image sensor according to this disclosure can provide AF functionality. Furthermore, the first to eighth transmission transistors of the first to eighth sub-pixels SPX11 to SPX18 can be sequentially turned on, and the pixel signal VOUT corresponding to the photoelectric charge generated by the first to eighth sub-pixels SPX11 to SPX18 can be sequentially output, thereby providing a high-resolution mode that allows AF functionality to be performed on a pixel-by-pixel basis. At this time, each of the plurality of pixels PX_X included in the first pixel group PG1h can output a pixel signal VOUT including AF information.

[0143] The image sensor according to embodiments of the present invention is not limited to the above-described readout methods (one or more). The process of outputting a pixel signal VOUT based on each of the first to eighth sub-pixels SPX11 to SPX18 can be performed using the following readout method (i.e., the RSSSSRSSSS readout method): the pixel signal VOUT is output when the photoelectric charge generated by the photodiodes of the four sub-pixels is sequentially accumulated in the floating diffusion region FD1, and then the reset operation is repeated. Alternatively, the process can be performed using the following readout method (i.e., the RSRSRSRSRSRSRSRS readout method): the pixel signal VOUT based on one sub-pixel is output, and then the reset operation is repeated.

[0144] Common Reference Figure 5 , Figure 6C and Figure 10 The first transmission transistor TX11 of the first sub-pixel SPX11 and the second transmission transistor TX12 of the second sub-pixel SPX12 can be turned on simultaneously, and the third to eighth transmission transistors of the third to eighth sub-pixels SPX13 to SPX18 can be turned on sequentially. That is, the first transmission control signal TS11 and the second transmission control signal TS12 can simultaneously change from logic low level to logic high level, and the third transmission control signal TS13 to the eighth transmission control signal TS18 can sequentially change from logic low level to logic high level.

[0145] The first pulse R of the ramp voltage RMP can be the pixel voltage VOUT when the floating diffusion region FD1 of the first pixel group PG1h is reset. The second pulse S1S2 can be the pixel signal VOUT based on the photoelectric charge generated by the first photodiode PD11 of the first sub-pixel SPX11 and the second photodiode PD12 of the second sub-pixel SPX12. The third pulses S1...S7 can be the pixel signals VOUT based on the photoelectric charge generated by the first to seventh photodiodes of the first to seventh sub-pixels SPX11 to SPX17, and the fourth pulses S1...S8 can be the pixel signals VOUT based on the photoelectric charge generated by the first to eighth photodiodes of the first to eighth sub-pixels SPX11 to SPX18.

[0146] That is, the first pixel group PG1h can first output a reset voltage as a pixel signal VOUT, and then output pixel signals VOUT based on the first sub-pixel SPX11 and the second sub-pixel SPX12, pixel signals VOUT based on the first to third sub-pixels SPX11 to SPX13, pixel signals VOUT based on the first to fourth sub-pixels SPX11 to SPX14, pixel signals VOUT based on the first to fifth sub-pixels SPX11 to SPX15, pixel signals VOUT based on the first to sixth sub-pixels SPX11 to SPX16, pixel signals VOUT based on the first to seventh sub-pixels SPX11 to SPX17, and pixel signals VOUT based on the first to eighth sub-pixels SPX11 to SPX18. This readout method can be a reset-signal-signal-signal-signal-signal-signal-signal (RSSSSSSS) readout method.

[0147] When performing the AF function, the image sensor according to this disclosure may not use some (i.e., unselected) horizontal pixels among the plurality of horizontal pixels PX_X included in the first pixel group PGLh. For example, since the first sub-pixel SPX11 and the second sub-pixel SPX12 simultaneously accumulate photoelectric charge in the floating diffusion region FD1, the first sub-pixel SPX11 and the second sub-pixel SPX12 may not be used for the AF function, while the third sub-pixel SPX13 to the eighth sub-pixel SPX18 may be used for the AF function.

[0148] exist Figure 10 The above description already outlines the case where only the first sub-pixel SPX11 and the second sub-pixel SPX12 are not used for AF function; however, the embodiments of the present invention are not limited to this. The first sub-pixel SPX11 and the second sub-pixel SPX12 can simultaneously accumulate photoelectric charge in the floating diffusion region FD1. Then, the third sub-pixel SPX13 and the fourth sub-pixel SPX14 can simultaneously accumulate photoelectric charge in the floating diffusion region FD1, thus the first to fourth sub-pixels SPX11 to SPX14 can be deactivated for AF function. Such a readout method can be a reset-signal-signal-signal-signal-signal-signal (RSSSSSS) readout method. In this case, the fourth to eighth sub-pixels SPX14 to SPX18 can sequentially accumulate photoelectric charge in the floating diffusion region FD1, and therefore can be used for AF function.

[0149] Alternatively, the first sub-pixel SPX11 and the second sub-pixel SPX12 can simultaneously accumulate photoelectric charge in the floating diffusion area FD1, followed by the third sub-pixel SPX13 and the fourth sub-pixel SPX14 simultaneously accumulating photoelectric charge in the floating diffusion area FD1, and then the fifth and sixth sub-pixels SPX15 and SPX16 simultaneously accumulating photoelectric charge in the floating diffusion area FD1. Thus, the first to sixth sub-pixels SPX11 to SPX16 can be deactivated for AF functionality. This readout method can be a reset-signal-signal-signal-signal-signal (RSSSSS) readout method. In this case, the seventh and eighth sub-pixels SPX17 and SPX18 can sequentially accumulate photoelectric charge in the floating diffusion area FD1, and therefore can be used for AF functionality.

[0150] Image sensors according to certain embodiments of the present invention can be operated such that the first to eighth sub-pixels SPX11 to SPX18 of the same pixel simultaneously accumulate photoelectric charge in the floating diffusion region FD1, thereby facilitating high-speed operation. However, in other embodiments, the image sensor can perform the following method: accumulating the photoelectric charge generated by the photodiodes of four (4) sub-pixels in the floating diffusion region FD1 and repeating the reset operation. For example, such an image sensor can perform a readout method (e.g., RSSSRSSS readout method) that repeats the following method twice: first, simultaneously turning on the two transmission transistors of a single pixel, and then sequentially turning on the other transmission transistors.

[0151] Based on the foregoing, those skilled in the art will recognize that readout methods used with image sensors according to embodiments of the present invention can be implemented differently.

[0152] Common Reference Figure 5 , Figure 6C and Figure 11Transmission transistors of sub-pixels with the same phase can be turned on simultaneously. For example, the first, third, fifth, and seventh transmission transistors of the first sub-pixel SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17 can be turned on simultaneously, and then the second, fourth, sixth, and eighth transmission transistors of the second sub-pixel SPX12, the fourth sub-pixel SPX14, the sixth sub-pixel SPX16, and the eighth sub-pixel SPX18 can be turned on simultaneously. That is, the first transmission control signal TS11, the third transmission control signal TS13, the fifth transmission control signal TS15, and the seventh transmission control signal TS17 can simultaneously transition from logic low to logic high, and the second transmission control signal TS12, the fourth transmission control signal TS14, the sixth transmission control signal TS16, and the eighth transmission control signal TS18 can simultaneously transition from logic low to logic high.

[0153] The first pulse R of the ramp voltage RMP can be a pulse corresponding to the pixel voltage VOUT when the floating diffusion region FD1 of the first pixel group PG1h is reset. The second pulse S1S3S5S7 can be pulses corresponding to the pixel signal VOUT based on the photoelectric charge generated by the first photodiode, third photodiode, fifth photodiode, and seventh photodiode of the first sub-pixel SPX11, third sub-pixel SPX13, fifth sub-pixel SPX15, and seventh sub-pixel SPX17. The third pulses S1...S8 can be pulses corresponding to the pixel signal VOUT based on the photoelectric charge generated by the first to eighth photodiodes of the first to eighth sub-pixels SPX11 to SPX18. That is, the first pixel group PG1h can first output a reset voltage as the pixel signal VOUT, then output the pixel signal VOUT based on the first sub-pixel SPX11, third sub-pixel SPX13, fifth sub-pixel SPX15, and seventh sub-pixel SPX17, and finally output the pixel signal VOUT based on the first to eighth sub-pixels SPX11 to SPX18. Such a readout method can be the reset-signal-signal (RSS) readout method.

[0154] An image sensor according to an embodiment of the present invention can perform autofocus (AF) on a pixel-by-pixel basis in low-resolution mode. That is, the AF function can be performed by comparing pixel signals VOUT based on the photoelectric charge generated by the first, third, fifth, and seventh photodiodes with pixel signals VOUT based on the photoelectric charge generated by the second, fourth, sixth, and eighth photodiodes. In low-light environments, the amount of photoelectric charge generated by a single photodiode is reduced; therefore, the image sensor can accumulate all the photoelectric charge generated by multiple photodiodes to appropriately perform the AF function.

[0155] However, the image sensor according to this disclosure is not limited to Figure 11 The illustrated embodiment. For example, in the reset-signal-reset-signal (RSRS) readout method, the first pixel group PG1h can output a pixel signal VOUT based on the first sub-pixel SPX11, the third sub-pixel SPX13, the fifth sub-pixel SPX15, and the seventh sub-pixel SPX17, and can be reset, and then can output a pixel signal VOUT based on the second sub-pixel SPX12, the fourth sub-pixel SPX14, the sixth sub-pixel SPX16, and the eighth sub-pixel SPX18. In the reset-signal-reset-signal-reset-signal-reset-signal (RSRSRSRS) readout method, the first pixel group PG1h can first output a reset voltage as a pixel signal VOUT, then output pixel signals VOUT based on the first and fifth sub-pixels SPX11 and SPX5, and can be reset, then output pixel signals VOUT based on the second and sixth sub-pixels SPX12 and SPX16, and can be reset again, then output pixel signals VOUT based on the third and seventh sub-pixels SPX13 and SPX17, and can be reset again, then output pixel signals VOUT based on the fourth and eighth sub-pixels SPX14 and SPX18. In the Reset-Signal-Signal-Reset-Signal-Signal (RSSRSS) readout method, the first pixel group PG1h can first output a reset voltage as a pixel signal VOUT, then output pixel signals VOUT based on the first and fifth sub-pixels SPX11 and SPX15, and can output pixel signals VOUT based on the first sub-pixel SPX11, the second sub-pixel SPX12, the fifth sub-pixel SPX15, and the sixth sub-pixel SPX16. It can also be reset, and can output pixel signals VOUT based on the third and seventh sub-pixels SPX13 and SPX17, and can output pixel signals VOUT based on the third sub-pixel SPX13, the fourth sub-pixel SPX14, the seventh sub-pixel SPX17, and the eighth sub-pixel SPX18. The image sensor according to this disclosure is not limited to operating based on the above-described methods (e.g., the Reset-Signal-Signal-Reset-Signal-Signal (RSSRSS) readout method). Various combinations of the above-described methods can be applied to the image sensor according to this disclosure.

[0156] Figure 12 This is yet another illustration of a pixel array of an image sensor according to certain embodiments of the concept of the present invention.

[0157] Reference Figure 3A and Figure 12The first subpixel array 110_1d includes a plurality of horizontal pixels PX_X arranged along the row direction (i.e., the first direction X) and the column direction (i.e., the second direction Y). It is further assumed that each horizontal pixel PX_X is operatively configured with a microlens ML.

[0158] In the illustrated embodiment, each of the first to fourth pixel groups PG1d to PG4d includes nine (9) horizontal pixels PX_X, wherein each horizontal pixel PX_X includes two (2) sub-pixels arranged adjacently in the first direction X. For example, each of the first to fourth pixel groups PG1d to PG4d may include eighteen sub-pixels arranged in three rows and six columns. For example, the first pixel group PG1d may include the first to eighteenth sub-pixels SPX11 to SPX118, the second pixel group PG2d may include the first to eighteenth sub-pixels SPX21 to SPX218, the third pixel group PG3d may include the first to eighteenth sub-pixels SPX31 to SPX318, and the fourth pixel group PG4d may include the first to eighteenth sub-pixels SPX41 to SPX418.

[0159] The first subpixel array 110_1d may include one or more color filters as described above. Here, each horizontal pixel PX_X in each of the first to fourth pixel groups PG1d to PG4d is associated with a selected color filter.

[0160] In one embodiment, the first subpixel array 110_1d can be configured according to a shared pixel structure in which two subpixels of each horizontal pixel PX_X share a floating diffusion region. Therefore, for each pixel group PG1d, PG2d, PG3d and PG4d, the first subpixel array 110_1d may include nine (9) floating diffusion regions.

[0161] In one approach, the first subpixel array 110_1d can be configured with a shared pixel structure in which horizontal pixels PX_X in the same row of a pixel group share a floating diffusion region. Alternatively, the first subpixel array 110_1d can be configured with a shared pixel structure in which horizontal pixels PX_X in the same column of a pixel group share a floating diffusion region. In this way, three (3) floating diffusion regions can be provided in each pixel group.

[0162] In another approach, horizontal pixels PX_X included in one or more pixel groups can share a floating diffusion region. For example, horizontal pixels PX_X included in different pixel groups can share different floating diffusion regions. Alternatively, horizontal pixels PX_X included in different pixel groups that are adjacent to each other in the row direction (i.e., the first direction X) can share different floating diffusion regions. Alternatively, for example, horizontal pixels PX_X included in different pixel groups that are adjacent to each other in the column direction (i.e., the second direction Y) can share different floating diffusion regions. Alternatively, for example, pixels PX_X included in the first to fourth pixel groups PG1d to PG4d can share different floating diffusion regions.

[0163] In an embodiment, the image sensor including the first sub-pixel array 110_1d can perform AF on a pixel-by-pixel basis when operating in a first mode (i.e., high-resolution mode), and on a group-by-pixel basis when operating in a second mode (i.e., low-resolution mode). For example, the resolution associated with the low-resolution mode may be less than or equal to approximately 1 / 9 of the resolution associated with the high-resolution mode.

[0164] As previously described, the image sensor according to embodiments of the present invention can effectively provide accurate autofocus (AF) functionality in various lighting environments using multiple resolution modes. Specific examples of high-resolution, low-resolution, and medium-resolution modes have been described above; however, embodiments of the present invention can use any reasonable number of resolution modes with various defined relationships. For example, the resolution associated with a medium-resolution mode can range from 1 / 9 to 1 / 3 of the resolution associated with a high-resolution mode.

[0165] Some of the foregoing embodiments have assumed the use of four (4) pixel groups. However, embodiments of the present invention are not limited thereto. For example, the horizontal pixels PX_X and / or vertical pixels PX_Y of the subpixel array can be functionally divided into 2, 4, 8, 16, or 32 pixel groups.

[0166] Although the inventive concept has been specifically shown and described with reference to embodiments thereof, it will be understood that various changes in form and detail may be made without departing from the spirit and scope of the appended claims.

Claims

1. An image sensor selectively adapted for use in a plurality of resolution modes including a low resolution mode, a medium resolution mode, and a high resolution mode, the image sensor comprising a pixel array and a row driver, the pixel array comprising a plurality of pixels, wherein each of the plurality of pixels comprising a first sub-pixel having a first photodiode and a second sub-pixel having a second photodiode, the first sub-pixel and the second sub-pixel being adjacently disposed and sharing a floating diffusion region, the row driver configured to provide a control signal to the pixel array to control performance of an auto-focus function, the performance of the auto-focus function including performing the auto-focus function in units of a pixel in the high resolution mode, performing the auto-focus function in units of pixels arranged in a same row or a same column in a pixel group in the medium resolution mode, and performing the auto-focus function in units of a pixel group in the low resolution mode, wherein a resolution corresponding to the low resolution mode is equal to or less than 1 / 4 of a resolution corresponding to the high resolution mode.

2. The image sensor of claim 1, wherein, the plurality of pixels comprising a first sub-pixel array and a second sub-pixel array, the first sub-pixel array comprising horizontal pixels, and the second sub-pixel array comprising vertical pixels.

3. The image sensor of claim 2, wherein, the row driver further configured to provide the control signal such that, in the high resolution mode, at least one of the first sub-pixel and the second sub-pixel of at least one of the horizontal pixels in the first sub-pixel array performs the auto-focus function.

4. The image sensor of claim 3, wherein, the row driver further configured to provide the control signal such that: photoelectric charges generated by the first sub-pixel of the at least one horizontal pixel are accumulated in the floating diffusion region, and then the photoelectric charges in the floating diffusion region are reset, and then photoelectric charges generated by the second sub-pixel of the at least one horizontal pixel are accumulated in the floating diffusion region.

5. The image sensor of claim 3, wherein, the at least one horizontal pixel in the first sub-pixel array does not include all of the horizontal pixels in the first sub-pixel array.

6. The image sensor of claim 2, wherein, the first sub-pixel array comprises a first horizontal pixel and a second horizontal pixel adjacently disposed, in response to a control signal provided from the row driver, a first floating diffusion region of the first horizontal pixel and a second floating diffusion region of the second horizontal pixel are electrically connected to each other, thereby causing the first horizontal pixel and the second horizontal pixel to share the floating diffusion region.

7. The image sensor of claim 2, wherein, the horizontal pixels comprise a first horizontal pixel and a second horizontal pixel sharing the floating diffusion region, and the row driver further configured to provide the control signal such that, in the low resolution mode, the first sub-pixel of the first horizontal pixel and the first sub-pixel of the second horizontal pixel simultaneously accumulate photoelectric charges in the floating diffusion region.

8. The image sensor of claim 2, wherein, the horizontal pixels of the first sub-pixel array comprise a first pixel group and a second pixel group adjacently disposed with the first pixel group, the first pixel group and the second pixel group respectively comprise horizontal pixels arranged in a first direction and a second direction, all of the horizontal pixels of the first pixel group are associated with a first color filter, and all of the horizontal pixels of the second pixel group are associated with a second color filter different from the first color filter.

9. The image sensor of claim 2, wherein, the horizontal pixels of the first sub-pixel array include a first pixel group and a second pixel group disposed adjacent to the first pixel group, the first pixel group and the second pixel group respectively include horizontal pixels disposed along a first direction and a second direction, at least one of the horizontal pixels of the first pixel group is associated with a first color filter, and at least one of the horizontal pixels of the second pixel group is associated with a second color filter different from the first color filter.

10. The image sensor of claim 9, wherein, the first color filter and the second color filter are respectively selected from a group of color filters including a red color filter, a blue color filter, a green color filter, a white color filter, and a yellow color filter.

11. The image sensor of claim 2, wherein, the horizontal pixels of the first sub-pixel array include a first pixel group and a second pixel group disposed adjacent to the first pixel group, the first pixel group and the second pixel group respectively include horizontal pixels disposed along a first direction and a second direction, at least one of the horizontal pixels of the first pixel group is associated with a first color filter, at least another one of the horizontal pixels of the first pixel group is associated with a second color filter different from the first color filter, and at least one of the horizontal pixels of the second pixel group is associated with a third color filter, at least another one of the horizontal pixels of the second pixel group is associated with a fourth color filter different from the third color filter.

12. The image sensor of claim 11, wherein, the first color filter and the third color filter are different color filters.

13. The image sensor of claim 12, wherein, the second color filter and the fourth color filter are the same color filter.

14. The image sensor of claim 2, wherein, the horizontal pixels of the first sub-pixel array include a first pixel group and a second pixel group disposed adjacent to the first pixel group, the first pixel group and the second pixel group respectively include horizontal pixels disposed along a first direction and a second direction, at least two of the horizontal pixels of the first pixel group are respectively associated with a first color filter and a second color filter different from the first color filter, and at least two of the horizontal pixels of the second pixel group are respectively associated with a third color filter and a fourth color filter different from the third color filter.

15. An image sensor selectively adapted for use in a plurality of resolution modes including a low resolution mode, a medium resolution mode, and a high resolution mode, the image sensor comprising a pixel array and a row driver, The pixel array includes a plurality of pixels arranged in a row direction and a column direction, wherein each of the plurality of pixels has a shared pixel structure, wherein the shared pixel structure comprises: a first sub-pixel including a first photoelectric conversion element that selectively transfers photoelectric charges to a floating diffusion region via a first transfer transistor in response to a first transfer signal, a second sub-pixel including a second photoelectric conversion element that selectively transfers photoelectric charges to the floating diffusion region via a second transfer transistor in response to a second transfer signal, a reset transistor configured to selectively reset photoelectric charges accumulated in the floating diffusion region in response to a reset signal, and a drive transistor and a selection transistor configured to selectively connect the floating diffusion region to a pixel signal output in response to a selection signal, the floating diffusion region, the reset transistor, the drive transistor, and the selection transistor are shared by the first sub-pixel and the second sub-pixel, and the first sub-pixel and the second sub-pixel are adjacently arranged, the row driver is configured to provide the first transfer signal, the second transfer signal, the reset signal, and the selection signal such that the execution of the auto-focus function includes: in the high-resolution mode, executing the auto-focus function in units of pixels; in the medium-resolution mode, executing the auto-focus function in units of pixels arranged in the same row in one pixel group; and in the low-resolution mode, executing the auto-focus function in units of pixel groups.

16. The image sensor according to claim 15, wherein a plurality of pixels included in the same pixel group among the plurality of pixel groups are configured to share a floating diffusion region, the row driver is further configured to provide the first transfer signal, the second transfer signal, the reset signal, and the selection signal such that photoelectric charges generated by the plurality of pixels included in the same pixel group are all accumulated in the floating diffusion region and then reset.

17. The image sensor according to claim 15, wherein at least two pixel groups adjacently arranged to each other are configured to share a floating diffusion region.

18. The image sensor of claim 15, wherein, the high-resolution mode has a first resolution, the medium-resolution mode has a second resolution, the second resolution being 1 / 4 of the first resolution to 1 / 2 of the first resolution, and the low-resolution mode has a third resolution, the third resolution being less than or equal to 1 / 4 of the first resolution.

19. An image sensor selectively adapted for use in a plurality of resolution modes including a low-resolution mode, a medium-resolution mode, and a high-resolution mode, the image sensor comprising: a row driver; a controller configured to control an operation of the row driver; and a pixel array including a plurality of pixels arranged in a row direction and a column direction and configured to provide a pixel signal in response to received incident light, wherein each of the plurality of pixels includes: a first sub-pixel having a first photodiode and a second sub-pixel having a second photodiode, the first sub-pixel and the second sub-pixel being adjacently arranged and sharing a floating diffusion region, wherein the row driver is configured to provide a control signal to the pixel array to control an execution of an auto-focus function such that the execution of the auto-focus function includes: in the high-resolution mode, executing the auto-focus function in units of pixels; in the medium-resolution mode, executing the auto-focus function in units of pixels arranged in the same row in one pixel group; and in the low-resolution mode, executing the auto-focus function in units of pixel groups.

20. The image sensor of claim 19, wherein, The high resolution mode has a first resolution, The medium resolution mode has a second resolution, the second resolution being 1 / 4 of the first resolution to 1 / 2 of the first resolution, and The low resolution mode has a third resolution, the third resolution being less than or equal to 1 / 4 of the first resolution.

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