Image sensing device and operating method thereof

Abstract

The present application relates to an image sensing device and an operation method thereof. An image sensing device may include a plurality of test pixel blocks and a signal processing unit. The test pixel blocks may be heated to different temperatures at the same time. The signal processing unit may read out a dark current according to the temperature of the test pixel blocks to extract pixel signals by color.

Description

Technical Field

[0001] Various embodiments of the disclosed technology generally relate to image sensing devices that detect light to generate image data and methods of operating the image sensing devices. Background Art

[0002] Image sensing devices can capture optical images using the properties of photosensitive semiconductor materials that react to light. As industries such as automobiles, medical treatment, computers, and communications have developed, image sensing devices with high performance can be widely used in various fields such as the Internet of Things (IOT), robots, security cameras, medical cameras, etc.

[0003] Image sensing devices can be divided into charge coupled device (CCD) type and complementary metal oxide semiconductor (CMOS) type. Compared with CMOS type image sensing devices, CCD type image sensing devices can have relatively high image quality. However, CCD type image sensing devices can have relatively large size and relatively high power consumption. On the contrary, compared with CCD type image sensing devices, CMOS image sensing devices can have relatively small size and relatively low power consumption. In addition, because CMOS type image sensing devices can be manufactured using CMOS manufacturing technology, optical sensors and signal processing circuits can be integrated in a single chip, which allows the image sensing device to have a smaller size and leads to a reduction in production costs. CMOS type image sensing devices have been developed for many applications including mobile devices. Summary of the invention

[0004] According to an example embodiment of the disclosed technology, an image sensing device may be provided. The image sensing device may include a first active test block, a second active test block, a first optical black test block, a second optical black test block, and a signal processing unit. The first active test block may include a plurality of first active pixels and a first heating element. The first active pixel may generate a first pixel signal corresponding to incident light. The first heating element may provide a first temperature for the first active pixel. The second active test block may include a plurality of second active pixels and a second heating element. The second active pixel may generate a second pixel signal corresponding to incident light. The second heating element may provide a second temperature higher than the first temperature for the second active pixel. The first optical black test block may include a plurality of first optical black pixels and a third heating element. The first optical black pixel may generate a third pixel signal independent of incident light. The third heating element may provide a first temperature for the first optical black pixel. The second optical black test block may include a plurality of second optical black pixels and a fourth heating element. The second optical black pixel may generate a fourth pixel signal independent of incident light. The fourth heating element may provide a second temperature for the second optical black pixel. The signal processing unit may process the first pixel signal to the fourth pixel signal.

[0005] According to example embodiments, an image sensing device may be provided. The image sensing device may include a plurality of test pixel blocks and a signal processing unit. The test pixel blocks may be heated to different temperatures at the same time. The signal processing unit may read out a dark current according to the temperature of the test pixel blocks to extract pixel signals by color.

[0006] According to example embodiments, a method for operating an image sensing device may be provided. In the method for operating the image sensing device, the temperature of a pixel array, which may include active pixels and optical black pixels, may be increased to a set temperature. A plurality of test pixel blocks may be heated at one time to provide a temperature higher than the set temperature to the test pixel blocks. Pixel signals according to the temperature may be extracted from the pixel array and the test pixel blocks. The pixel signals may be used to obtain pedestal information of the pixel array. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The above and other aspects, features, and advantages of the subject matter of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[0008] Figure 1 is a block diagram illustrating a photographing device according to an example embodiment of the disclosed technology.

[0009] Figure 2 is a graph showing dark currents of active pixels and optical black pixels.

[0010] Figure 3 is a block diagram illustrating a pixel array according to an example implementation of the disclosed technology.

[0011] Figure 4A and Figure 4B It is shown Figure 3 A view of the active test blocks in .

[0012] Figure 5A and Figure 5B It is shown Figure 3 View of the optical test block in Figure 1.

[0013] Figure 6 is a flowchart illustrating a method of operating an image sensing device according to an example embodiment of the disclosed technology. DETAILED DESCRIPTION

[0014] Various embodiments of the disclosed technology will be described in more detail with reference to the accompanying drawings. The accompanying drawings are schematic diagrams of various embodiments (and intermediate structures). As such, it is expected that the configurations and shapes illustrated will vary due to, for example, manufacturing techniques and / or tolerances. Therefore, the described embodiments should not be interpreted as limited to the specific configurations and shapes shown herein, but may include deviations in configurations and shapes that do not depart from the spirit and scope of the disclosed technology.

[0015] The embodiments of the disclosed technology should not be interpreted as limiting the concept of the present invention. Although some embodiments of the disclosed technology will be shown and described, it will be understood by those skilled in the art that various changes may be made to some embodiments of the disclosed technology.

[0016] Figure 1 is a block diagram illustrating a photographing device according to an example embodiment, and Figure 2 is a graph showing dark currents of active pixels and optical black pixels.

[0017] Reference Figure 1 , the photographing device 1000 may include a digital camera configured to photograph a still image, a digital video camera configured to photograph a video, etc. For example, the photographing device 1000 may include a digital single-lens reflex camera (DSLR), a mirrorless camera, a smart phone, etc., but is not limited thereto. The photographing device 1000 may include a lens and a photographing element configured to photograph an object and generate an image.

[0018] The photographing device 1000 may include an image sensing device 100 and an image signal processing unit 200 .

[0019] The image sensing device 100 may include a complementary metal oxide semiconductor image sensor (CIS) configured to convert an optical signal into an electrical signal. The image sensing device 100 may provide image data formed by converting the optical signal into an electrical signal to the image signal processing unit 200. On / off, operation mode, sensitivity, etc. of the image sensing device 100 may be controlled by a sensor control signal from the image signal processing unit 200.

[0020] The image sensing device 100 may include a pixel array 110, a row driver 120, a correlated double sampler (CDS) 130, an analog-to-digital converter (ADC) 140, an output buffer 150, a column driver 160, a timing controller 170, a temperature sensor 180, and a substrate information storage 190. The image sensing device 100 may include additional components, such as, but not limited to, Figure 1 Those components shown.

[0021] The pixel array 110 may include a plurality of unit pixels having a plurality of rows and a plurality of columns. In an example embodiment, the unit pixels may be arranged in a two-dimensional pixel array including rows and columns. Alternatively, the unit pixels may be arranged in a three-dimensional pixel array.

[0022] The unit pixel may generate an electrical signal in a unit pixel unit or in a pixel group unit. The unit pixels in the pixel group may share at least a specific internal circuit in common.

[0023] The unit pixel may include at least one active pixel and at least one optical black pixel. The active pixel may detect incident light to generate a pixel signal corresponding to the intensity of the incident light. The optical black pixel may have a structure substantially the same as that of the active pixel. The optical black pixel may include a structure for blocking incident light to generate a pixel signal that is unrelated to the incident light.

[0024] The pixel array 110 may receive driving signals including a row selection signal, a pixel reset signal, a transmission signal, etc. from the row driver 120. Corresponding unit pixels of the pixel array 110 may be activated to perform operations corresponding to the row selection signal, the pixel reset signal, and the transmission signal.

[0025] The row driver 120 may activate the pixel array 110 based on the command and control signal of the timing controller 170 to perform a specific operation of the unit pixel in the corresponding row. In an example embodiment, the row driver 120 may select at least one unit pixel arranged in at least one row of the pixel array 110. The row driver 120 may generate a row selection signal for selecting at least one row in a plurality of rows. The row driver 120 may sequentially enable a pixel reset signal and a transmission signal for the pixel corresponding to the selected row. Therefore, the analog reference signal and the image signal generated from each pixel of the selected row may be sequentially sent to the CDS 130. The reference signal may be an electrical signal provided to the CDS 130 when a sensing node (e.g., a floating diffusion node) of a unit pixel may be reset. The image signal may be an electrical signal provided to the CDS 130 when a photocharge generated by a unit pixel may be accumulated in a sensing node. The reference signal that may represent the inherent reset noise of the pixel and the image signal that may represent the intensity of the incident light may be referred to as a pixel signal.

[0026] CIS may use correlated double sampling to remove undesired pixel offset values, such as fixed pattern noise, by sampling the pixel signal twice to remove the difference between the two samples. For example, correlated double sampling may compare pixel output voltages obtainable before and after photocharges generated by incident light may be accumulated in a sensing node to each other to remove undesired offset values, thereby measuring a pixel output voltage based only on the incident light. In an example embodiment, the CDS 130 may sequentially sample and hold a reference signal and an image signal provided to a column line from the pixel array 110. Thus, the CDS 130 may sample and hold a reference signal and an image signal corresponding to each column of the pixel array 110.

[0027] The CDS 130 may transmit the reference signal and the image signal of each column as a correlated double sampling signal to the ADC 140 based on a control signal of the timing controller 170 .

[0028] ADC 140 may convert a CDS signal for each column that may be output from CDS 130 into a digital signal. ADC 140 may then output a digital signal. In an example embodiment, ADC 140 may include a ramp comparison type ADC. The ramp comparison type ADC may include a comparison circuit and a counter. The comparison circuit may compare a ramp signal that may increase or decrease according to time with an analog pixel signal. The counter may perform a counting operation until the ramp signal may match the analog pixel signal. ADC 140 may convert a CDS signal generated by CDS 130 for each column into a digital signal.

[0029] ADC 140 may include a plurality of column counters corresponding to the columns of pixel array 110. Each column of pixel array 110 may be connected to a column counter. Image data and noise data may be generated by converting a CDS signal corresponding to a column into a digital signal using a column counter. Alternatively, ADC 140 may include a global counter. ADC 140 may convert a CDS signal corresponding to a column into a digital signal using a global code provided from a global counter. Image data may include a digital signal generated by converting a pixel signal output from at least one image pixel. Noise data may include a digital signal generated by converting a pixel signal output from at least one optical black pixel.

[0030] The output buffer 150 may temporarily hold and output the image data and noise data by column provided from the ADC 140. The output buffer 150 may temporarily store the image data and noise data output from the ADC 140 based on a control signal of the timing controller 170. The output buffer 150 may serve as an interface configured to compensate for a difference between a transmission speed or a processing speed of the image sensing device 100 and other devices connected to the image sensing device 100.

[0031] The column driver 160 may select a column of the output buffer 150 based on a control signal of the timing controller 170. The column driver 160 may control the output buffer 150 to sequentially output the image data and the noise data temporarily stored in the selected column of the output buffer 150. In an example embodiment, the column driver 160 may receive an address signal from the timing controller 170. The column driver 160 may generate a column selection signal based on the address signal to select a column of the output buffer 150, thereby outputting the image data and the noise data of the selected column from the output buffer 150 to the image signal processing unit 200.

[0032] The timing controller 170 may provide a clock signal for operating the image sensing device 100, a control signal for timing control, and an address signal for selecting a row or a column to at least one of the row driver 120, the CDS 130, the ADC 140, the output buffer 150, the column driver 160, the temperature sensor 180, and the substrate information memory 190. In example embodiments, the timing controller 170 may include a logic control circuit, a phase-locked loop (PLL) circuit, a timing control circuit, a communication interface circuit, and the like.

[0033] The timing controller 170 may receive temperature information from the temperature sensor 180 according to the sensor control signal of the image signal processing unit 200. The timing controller 170 may read substrate information corresponding to the temperature information from the substrate information storage 190. The timing controller 170 may transmit the read substrate information to the image signal processing unit 200 in response to the sensor control signal. The image signal processing unit 200 may perform substrate correction based on the substrate information.

[0034] The image data may include a dark noise component representing a dark current, which may be generated by factors other than the incident light. Other factors may include factors such as temperature, inherent noise caused by the pixel structure, etc. The dark current may be generated by dangling bonds generated on the surface of the substrate. The charge of the dark current that is independent of the incident light can be introduced into a sensing area of ​​the pixel, such as a floating diffusion area, so that the image data may include a dark noise component that is independent of the incident light. Because the dark noise component may degrade the image quality, it may be necessary to use noise data generated from an optical black pixel including a structure configured to block incident light to remove the dark current component.

[0035] In order to completely remove the dark noise component in the image data, the noise data may be substantially the same as the dark noise component of the image data.

[0036] Figure 2 is a graph showing the dark current (e- / s; electron charge per second) of active pixels and optical black pixels.

[0037] The dark current of an active pixel can be referred to as the dark noise component of the image data. The dark current of an optically black pixel can be referred to as the noise data. Figure 2 As shown, the dark current of the active pixel may be different from the dark current of the optical black pixel. The difference between the dark current of the active pixel and the optical black pixel may increase in proportion to the increase in the junction temperature of the substrate with the pixel. Figure 2 , the difference between the dark currents of the active pixel and the optical black pixel when the junction temperature is about 90°C is greater than the difference between the dark currents when the junction temperature is about 60°C.

[0038] If the dark noise component in the image data is removed using noise data without considering the difference between the dark currents of the active pixels and the optical black pixels, the dark noise component of the image data cannot be completely removed. In this case, correction of the noise data is required, that is, correcting the noise data to a level substantially the same as that of the dark noise component of the image data, or correcting the noise data to represent the dark noise component of the image data. This correction may be referred to as a base correction.

[0039] Refer again Figure 1 , a base correction may be performed using base information for correcting noise data so that the noise data is at a level substantially the same as a level of a dark noise component of the image data at a corresponding temperature. Therefore, the base information may be changed according to the temperature. The base information may include a base correction value for correcting the noise data. The timing controller 170 may read the base information corresponding to the temperature information from the base information storage 190. Then, the timing controller 170 may send the read base information to the image signal processing unit 200.

[0040] In an example embodiment, the substrate information may include a substrate correction value determined based on the color of the active pixel. For example, the substrate correction values ​​for red, green, and blue may be different from each other. For different colors, the difference between the dark currents of the active pixel and the optical black pixel at the same temperature may be different from each other due to the difference between the pixel structures caused by the color (e.g., the difference between the filters on the substrate). The substrate correction may be performed using the substrate correction value independently determined based on the color to accurately remove the dark noise component of the image data. The temperature of the exemplary embodiment may be the temperature of the substrate having the pixel array 110.

[0041] The temperature sensor 180 may measure the internal temperature of the image sensing device 100 according to the control of the timing controller 170. The temperature sensor 180 may transmit temperature information to the timing controller 170. In an example embodiment, the temperature sensor 180 may measure the temperature of the substrate having the pixel array 110. When the measured temperature of the substrate having the pixel array 110 is about 60° C., the temperature of the substrate in the test area may increase according to the test block, which will be described later.

[0042] The substrate information storage 190 may store substrate information corresponding to a predetermined temperature. The predetermined temperature may be experimentally determined as a temperature at which substrate correction is required during testing. The substrate information corresponding to the temperature may include a substrate correction value for color. The substrate information storage 190 may use a one-time programmable (OTP) memory in the substrate information storage 190 to store the substrate information.

[0043] exist Figure 1 In the embodiment of the present invention, the temperature sensor 180 and the base information storage 190 may be arranged in the image sensing device 100. Alternatively, at least one of the temperature sensor 180 and the base information storage 190 may be arranged outside the image sensing device 100. For example, at least one of the temperature sensor 180 and the base information storage 190 may be arranged in the image signal processing unit 200.

[0044] The image signal processing unit 200 may process image data input from the image sensing device 100. The image signal processing unit 200 may control the image sensing device 100 according to the processing result or the external input signal. The image signal processing unit 200 may reduce noise from the image data. The image signal processing unit 200 may perform image signal processing for improving image quality, such as gamma correction, color filter array interpolation, color matrix, color correction, color enhancement, etc. In addition, the image signal processing unit 200 may perform image signal processing for improving image quality to compress image data, thereby generating an image file or restoring image data from an image from an image file. The compression of the image data may be a reversible type or an irreversible type. When the image may be a still image, the compression of the image data may include Joint Photographic Experts Group (JPEG) or JPEG 2000. In contrast, when the image may be a video, a plurality of frames may be compressed according to the Moving Picture Experts Group (MPEG) standard to generate a video file. For example, a video file may be generated according to the Exchangeable Image File Format (EXIF).

[0045] The image data output from the image signal processing unit 200 may be stored in an internal memory or an external memory of the photographing apparatus 1000 according to a user's request or automatically. The image data may be displayed on a display.

[0046] The image signal processing unit 200 may perform non-sharpness processing, blur processing, edge emphasis processing, image interpretation processing, image recognition processing, image effect processing, and the like.

[0047] The image signal processing unit 200 may perform display image signal processing for the display, for example, brightness level control, color correction, contrast control, contour emphasis control, picture segmentation processing, character image generation, image synthesis processing, and the like.

[0048] The image signal processing unit 200 may include a base corrector 210 .

[0049] The substrate corrector 210 may request the image sensing device 100 for substrate information using the sensor control signal. The substrate corrector 210 may receive the substrate information corresponding to the current temperature from the image sensing device 100.

[0050] The substrate information may include a substrate correction value for correcting the noise data to a level substantially the same as the level of the dark noise component of the image data or representing the dark noise component of the image data. The substrate correction value may be a ratio between the dark current of an active pixel corresponding to a specific color (e.g., red, green, or blue) and the dark current of a corresponding optical black pixel at a specific temperature (e.g., about 60° C., about 70° C., about 80° C., or about 90° C.). The substrate corrector 210 may calculate a substrate correction value (e.g., 1.8) for the noise data corresponding to the specific color (e.g., red) to correct the noise data so that the noise data is at a level substantially the same as the level of the dark noise component of the image data. The substrate correction may be performed independently for each color.

[0051] The base corrector 210 can provide corrected noise data for each color by performing base correction. By calculating image data corresponding to a specific color (e.g., red) and corrected noise data corresponding to the same color (e.g., red) of the image data, dark noise components can be removed from the image data.

[0052] Figure 3 is a block diagram illustrating a pixel array according to example embodiments.

[0053] Reference Figure 3 , the illustrated example of pixel array 110 may include separate regions, such as an active pixel array 310 , an optical black pixel array 320 , an active test block 330 , and an optical black test block 340 .

[0054] The active test block 330 may be disposed on one side of the active pixel array 310. The optical black test block 340 may be disposed on the other side of the optical black pixel array 320. Figure 3 In the example shown, the active test block 330 and the optical black test block 340 may be disposed between the active pixel array 310 and the optical black pixel array 320 .

[0055] According to example embodiments, relative positions and sizes of the active pixel array 310 , the optical black pixel array 320 , the active test block 330 , and the optical black test block 340 may vary.

[0056] The active pixel array 310 may include active pixels that detect incident light to generate pixel signals. Figure 3 , one block of the active pixel array 310 may be indicated by “A”.

[0057] The optical black pixel array 320 may include optical black pixels configured to generate pixel signals without being exposed to incident light and thus the pixel signals are independent of the incident light. Figure 3, one block of the optical black pixel array 320 may be indicated by “B”.

[0058] The active test block 330 may include elements configured to control active pixels and the temperature of the active pixels of the active pixel array 310. The active test block 330 may be used to obtain dark currents of active pixels by color at a specific set temperature during testing.

[0059] In an example embodiment, the active test block 330 may include a first active test block 330A, a second active test block 330B, and a third active test block 330C. The first active test block 330A, the second active test block 330B, and the third active test block 330C may have different temperatures. For example, when the temperature of block A of the active pixel array 310 may have a temperature of approximately 60° C., the first active test block 330A may have a first temperature (e.g., approximately 70° C.), the second active test block 330B may have a second temperature (e.g., approximately 80° C.), and the third active test block 330C may have a third temperature (e.g., approximately 90° C.). The implementation of the active test block 330 may vary with respect to the number of active test blocks, without limitation as Figure 3 Specifically, the active test block 330 may include a Figure 3 More or less active test blocks for specific examples in .

[0060] The optical black test block 340 may include elements configured to control the optical black pixels and the temperature of the optical black pixels of the optical black pixel array 320. The optical black test block 340 may be used to obtain dark currents of the optical black pixels by color at a set temperature during testing.

[0061] In example embodiments, the optical black test block 340 may include a first optical black test block 340A, a second optical black test block 340B, and a third optical black test block 340C, but is not limited thereto. The first optical black test block 340A, the second optical black test block 340B, and the third optical black test block 340C may have different temperatures. For example, when the temperature of block B of the optical black pixel array 320 may have a temperature of about 60° C., the first optical black test block 340A may have a first temperature (e.g., about 70° C.), the second optical black test block 340B may have a second temperature (e.g., about 80° C.), and the third optical black test block 340C may have a third temperature (e.g., about 90° C.).

[0062] Figure 4A and Figure 4B It is shown Figure 3 A view of the active test blocks in . Figure 4B is along Figure 4A A cross-sectional view taken along line AA' in FIG.

[0063] Figure 4A and Figure 4B The first active test block 330A may be exemplarily shown. Figure 4A and Figure 4B , the first active test block 330A may include a plurality of first active pixels AP and a first heating element 337. The second active test block 330B and the third active test block 330C may have a configuration substantially the same as that of the first active test block 330A. However, different temperatures may be applied to the first active test block 330A, the second active test block 330B, and the third active test block 330C. Therefore, the second active test block 330B may include a plurality of second active pixels and a second heating element. The third active test block 330C may include a plurality of third active pixels and a third heating element. Block A of the active pixel array 310 may include only a plurality of active pixels without a heating element.

[0064] Reference Figure 4A and Figure 4B , the first active test block 330A may include a first active pixel AP and a first heating element 337 .

[0065] The first active pixels AP may be arranged in a matrix shape on a plane. Figure 4A In the embodiment, the active pixels AP may be arranged in a (6×6) matrix shape including six rows and six columns, but is not limited thereto. Each first active pixel AP may have Figure 3 The structure of the active pixels in the active pixel array 310 is basically the same as the structure.

[0066] The first active pixels AP may be arranged on a substrate 331 having a doping region 332. Each of the first active pixels AP may include an optical mesh structure 334, a filter 335, and a micro lens 336.

[0067] The substrate 331 may have an upper surface and a lower surface opposite to the upper surface. The substrate 331 may include a P-type or N-type bulk substrate, a P-type bulk substrate with a P-type or N-type epitaxial layer, an N-type bulk substrate with a P-type or N-type epitaxial layer, etc. The substrate 331 may include a P-conductivity type or N-conductivity type doped region 332.

[0068] The doping region 332 may include a photoelectric conversion region arranged corresponding to each first active pixel AP. The photoelectric conversion region may be an N-type doped region formed by injecting N-type ions into the substrate 331. In an example embodiment, the photoelectric conversion region may include a plurality of stacked doping regions. A lower doping region may be formed by injecting N+ type ions. An upper doping region may be formed by injecting N-type ions. In order to increase the fill factor used to represent the light receiving efficiency, the photoelectric conversion region may be formed over a large area. An isolation layer that may have a vertical groove shape may be formed between the photoelectric conversion regions of the first active pixel AP to electrically and optically isolate the photoelectric conversion regions from each other.

[0069] The photoelectric conversion region can generate and accumulate photoelectric charges corresponding to the incident light intensity. The photoelectric charges accumulated in the photoelectric conversion region can be converted into a pixel signal as an electrical signal by an additional pixel signal circuit. For example, the pixel signal circuit may include a 4-transistor transfer transistor, a floating diffusion region, a reset transistor, a source follower transistor, and a selection transistor, etc., without limitation thereto. The pixel signal circuit may be included in the wiring element 333 below the doped region 332.

[0070] The optical grid structure 334 can prevent optical crosstalk between adjacent first active pixels AP. That is, the optical grid structure 334 can block the incident light that can be incident to the filter 335 of the first active pixel from being transmitted to the filter 335 of another first active pixel. The optical grid structure 334 can be arranged along the boundary between adjacent first active pixels AP. The optical grid structure 334 may include a material for blocking light. For example, the optical grid structure 334 may include tungsten (W) having high light absorption.

[0071] The filter 335 may be formed on the substrate 331 to selectively transmit light having a specific wavelength band (e.g., red, green, blue, magenta, yellow, cyan, etc.) through the filter 335. Each first active pixel may be named corresponding to the type of the filter 335 in the first active pixel. For example, the first active pixel AP including the filter 335 through which red light can pass may be defined by a red active pixel. The first active pixel AP including the filter 335 through which green light can pass may be defined by a green active pixel. The first active pixel AP including the filter 335 through which blue light can pass may be defined by a blue active pixel.

[0072] A microlens 336 may be formed on the filter 335. The microlens 336 may increase the light gathering capability of the incident light to improve the light receiving efficiency of the photoelectric conversion region in the first active pixel. Figure 4B In the embodiment of the present invention, one first active pixel may correspond to one microlens 336. Alternatively, a plurality of first active pixels may correspond to one microlens 336.

[0073] The first heating element 337 may be arranged below the first active pixel AP. The first heating element 337 may be arranged between the wiring element 333 and the doping region 332. The first heating element 337 may generate heat corresponding to the first active test block 330A. The first heating element 337 may transfer heat to the first active pixel AP. For example, the first heating element 337 may heat the first active test block 330A to a first temperature (e.g., about 70°C). The second heating element may heat the second active test block 330B to a second temperature (e.g., about 80°C). The third heating element may heat the third active test block 330C to a third temperature (e.g., about 90°C).

[0074] The first heating element 337 may be disposed under the first active pixel AP to transfer heat to the first active pixel AP. The position of the first heating element 337 may vary. For example, the first heating element 337 may be located at a position where heat can be effectively transferred to the first active pixel AP.

[0075] Figure 5A and Figure 5B It is shown Figure 3 View of the optical test block in Figure 1. Figure 5B is along Figure 5A A cross-sectional view taken along line BB' in FIG.

[0076] Figure 5A and Figure 5B The first optical black test block 340A may be exemplarily shown. Figure 5A , the first optical black test block 340A may include a plurality of first optical black pixels OBP and a first heating element 347. The second optical black test block 340B and the third optical black test block 340C may have a configuration substantially the same as that of the first optical black test block 340A. However, different temperatures may be applied to the first optical black test block 340A, the second optical black test block 340B, and the third optical black test block 340C. That is, the second optical black test block 340B may include a plurality of second optical black pixels and a second heating element. The third optical black test block 340C may include a plurality of third optical black pixels and a third heating element. Block B of the optical black pixel array 320 may include only a plurality of optical black pixels without including a heating element.

[0077] Reference Figure 5A and Figure 5B , the first optical black test block 340A may include a first optical black pixel OBP and a first heating element 347 .

[0078] The first optical black pixels OBP may be arranged in a matrix shape on a plane. Figure 5AIn the embodiment, the optical black pixels OBP may be arranged in a (6×6) matrix shape including six rows and six columns, but is not limited thereto. Each first optical black pixel OBP may have Figure 3 The structure of the optical black pixels in the optical black pixel array 320 is basically the same as the structure.

[0079] Each first optical black pixel OBP may include a substrate 341, a light shielding structure 344, a filter 345, a microlens 346, and a first heating element 347. The first optical black pixel OBP may have a configuration substantially the same as that of the second optical black pixel and the third optical black pixel. Therefore, only the first optical black pixel OBP may be shown in detail, and any further description of the second optical black pixel and the third optical black pixel may be omitted here for the sake of brevity.

[0080] The substrate 341 and the microlens 346 may be Figure 4B The substrate 331 and the microlens 336 in FIG. 34 are substantially the same. Therefore, for the sake of brevity, any further description of the substrate 341 and the microlens 346 may be omitted here. The substrate 341 may include a doped region 342 and a wiring element 343 including a pixel signal circuit.

[0081] and Figure 4B Unlike the optical mesh structure 334 in FIG. 3 , the light shielding structure 344 may be arranged on all the first optical black pixels OBP. Therefore, the light shielding structure 344 may block light incident to the upper region of the light shielding structure 344 so that the light may not be transmitted to the substrate 341 .

[0082] The light shielding structure 344 may include a material for blocking light. For example, the light shielding structure 344 may include tungsten (W) having high light absorption. The light shielding structure 344 may be formed by the process for forming the optical mesh structure 334.

[0083] The filter 345 may be arranged above the light shielding structure 344, which is similar to Figure 4B The filters 335 arranged between adjacent optical grid structures 334 in the first optical black pixel are different. The first optical black pixel OBP may be named based on the type of the filter 345 in the corresponding first optical black pixel. For example, the first optical black pixel OBP including the filter 345 through which red light can pass may be referred to as a red optical black pixel. The first optical black pixel OBP including the filter 345 through which green light can pass may be referred to as a green optical black pixel. The first optical black pixel OBP including the filter 345 through which blue light can pass may be referred to as a blue optical black pixel.

[0084] Except for the above differences, the optical filter 345 may be substantially the same as the optical filter 335. Therefore, for the sake of brevity, any further description regarding the optical filter 345 may be omitted herein.

[0085] The first heating element 347 may be arranged below the first optical black pixel OBP. The first heating element 347 may be arranged between the wiring element 343 and the doping region 342. The first heating element 347 may generate heat corresponding to the first optical black test block 340A. The first heating element 347 may transfer heat to the first optical black pixel OBP. For example, the first heating element 347 may heat the first optical black test block 340A to a temperature of approximately 70°C. The second heating element may heat the second optical black test block 340B to a temperature of approximately 80°C. The third heating element may heat the third optical black test block 340C to a temperature of approximately 90°C.

[0086] The first heating element 347 may be disposed under the first optical black pixel OBP to transfer heat to the first optical black pixel OBP, but is not limited thereto. That is, the first heating element 347 may be located at a position where heat can be effectively transferred to the first optical black pixel OBP.

[0087] Figure 6 is a flowchart illustrating a method of operating an image sensing device according to example embodiments.

[0088] Figure 6 Operations for testing a chip including an image sensing device may be shown. In addition, operations may be performed under conditions where light may be almost completely or completely blocked. Operations may be performed to obtain substrate information that may represent a ratio between a dark current of an active pixel generated independently of light and a dark current of an optical black pixel.

[0089] In step S110, when a set temperature (e.g., about 60° C.) can be detected from the pixel array, in step S120, the first to third heating elements of the active test block and the first to third heating elements of the optical black test block can be heated to the set temperature corresponding to the heating control signal. The heated first to third heating elements can reach different temperatures higher than the set temperature. The first heating element, the second heating element, and the third heating element can reach about 70° C., about 80° C., and about 90° C., respectively, at the same time.

[0090] Pixel signals corresponding to the temperature may be extracted from the active pixels and the optical black pixels. In an example embodiment, a first pixel signal may be extracted from an active pixel in an "A" block having a temperature of approximately 60° C. A second pixel signal may be extracted from an optical black pixel in a "B" block having a temperature of approximately 60° C.

[0091] The third pixel signal may be extracted from the first active pixel in the first active test block 330A having a temperature of about 70° C. The fourth pixel signal may be extracted from the first optical black pixel in the first optical black test block having a temperature of about 70° C.

[0092] A fifth pixel signal may be extracted from a second active pixel in a second active test block having a temperature of approximately 80° C. A sixth pixel signal may be extracted from a second optical black pixel in a second optical black test block having a temperature of approximately 80° C.

[0093] A seventh pixel signal may be extracted from a third active pixel in a third active test block having a temperature of approximately 90° C. An eighth pixel signal may be extracted from a third optical black pixel in a third optical black test block having a temperature of approximately 90° C.

[0094] Each first active pixel of the first active test block having a set temperature (e.g., about 70° C.) may generate a third pixel signal. The third pixel signal of each first active pixel may be converted into a digital value by the CDS, the ADC, and the output buffer. The digital value may then be output. In an example embodiment, the first active pixel may include a red active pixel, a green active pixel, and a blue active pixel. In this case, the test device may calculate a digital value corresponding to the red active pixel, for example, an average value calculation to obtain red active test data. The test device may calculate a digital value corresponding to the green active pixel, for example, an average value calculation to obtain green active test data. The test device may calculate a digital value corresponding to the blue active pixel, for example, an average value calculation to obtain blue active test data. The red active test data may represent a dark noise component caused by a dark current generated in the red active pixel at a set temperature. The green active test data may represent a dark noise component caused by a dark current generated in the green active pixel at a set temperature. The blue active test data may represent a dark noise component caused by a dark current generated in the blue active pixel at a set temperature. The red active test data, the green active test data, and the blue active test data may be referred to as first test data.

[0095] Although it has been described above that the first test data includes active test data from the first active test block, the first test data obtained in step S130 may also include active test data from the second active test block and the third active test block. The active test data corresponding to the colors of the second active test block and the third active test block may be obtained similarly to the process for obtaining active test data corresponding to the color of the first active test block 330A. Therefore, for the sake of brevity, any further description of the process for obtaining active test data corresponding to the colors of the second active test block and the third active test block may be omitted here.

[0096] Each first optical black pixel of the first optical black test block 340A having a set temperature (e.g., about 70°C) may generate a fourth pixel signal. The fourth pixel signal of each first optical black pixel may be converted into a digital value by the CDS, the ADC, and the output buffer. The digital value may then be output. In an example embodiment, the first optical black pixel may include a red optical black pixel, a green optical black pixel, and a blue optical black pixel. In this case, the test device may calculate a digital value corresponding to the red optical black pixel, for example, an average value calculation to obtain red optical black test data. The test device may calculate a digital value corresponding to the green optical black pixel, for example, an average value calculation to obtain green optical black test data. The test device may calculate a digital value corresponding to the blue optical black pixel, for example, an average value calculation to obtain blue optical black test data. The red optical black test data may represent a dark noise component caused by a dark current generated in the red optical black pixel at a set temperature. The green optical black test data may represent a dark noise component caused by a dark current generated in the green optical black pixel at a set temperature. The blue optical black test data may represent a dark noise component caused by a dark current generated in the blue optical black pixel at a set temperature. The red optical black test data, the green optical black test data, and the blue optical black test data may be referred to as second test data.

[0097] Although it has been described above that the second test data includes optical black test data from the first optical black test block, the second test data obtained in step S140 may also include optical black test data from the second optical black test block and the third optical black test block. The optical black test data corresponding to the colors of the second optical black test block and the third optical black test block may be obtained similarly to the process for obtaining the optical black test data corresponding to the color of the first optical black test block. Therefore, for the sake of brevity, any further description of the process for obtaining the optical black test data according to the colors of the second optical black test block and the third optical black test block may be omitted herein.

[0098] In step S150, substrate information about each set temperature may be generated based on the first test data and the second test data. Therefore, the substrate information may be associated with the pixel signal of the active pixel AP and the pixel signal of the optical black pixel OBP.

[0099] In an example embodiment, a value obtained by dividing the red active test data of the first test data by the red optical black test data of the second test data may be determined as a red substrate correction value relative to a set temperature. Therefore, the red substrate correction value relative to the set temperature may be a ratio between a dark noise component of a dark current of a red active pixel and a dark noise component of a dark current of a red optical black pixel.

[0100] A value obtained by dividing the green active test data of the first test data by the green optical black test data of the second test data may be determined as a green substrate correction value relative to a set temperature. Therefore, the green substrate correction value relative to a set temperature may be a ratio between a dark noise component of a dark current of a green active pixel and a dark noise component of a dark current of a green optical black pixel.

[0101] A value obtained by dividing the blue active test data of the first test data by the blue optical black test data of the second test data may be determined as a blue substrate correction value relative to a set temperature. Therefore, the blue substrate correction value relative to a set temperature may be a ratio between a dark noise component of a dark current of a blue active pixel and a dark noise component of a dark current of a blue optical black pixel.

[0102] In step S160, the base information including the red base correction value, the green base correction value, and the blue base correction value may correspond to the set temperature. The base information may then be stored in a base information storage.

[0103] The base corrector of the image signal processing unit can calculate a base correction value (e.g., a red base correction value) corresponding to the same color for noise data corresponding to a specific color to perform base correction, thereby providing noise data at a level substantially the same as that of a dark noise component of the image data.

[0104] According to some implementations of the disclosed technology, dark noise components may be accurately removed from image data by including a test block for generating background information to a chip including an image sensing device and performing background correction using the background information independently stored in the chip.

[0105] In addition, the test block can be heated to different temperatures at the same time, and the substrate information corresponding to the different temperatures can be obtained. Therefore, the substrate correction can be performed using the substrate information corresponding to the different temperatures, which allows the dark noise component to be removed more accurately from the image data.

[0106] Although the patent document contains many details in the disclosed examples, these should not be interpreted as limitations on the scope of any invention or the scope of what is claimed, but rather as descriptions of features that may be unique to a particular embodiment of a particular invention. Certain features described in the patent document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination. In addition, although features may be described as working in certain combinations and even initially claimed as such, in some cases, one or more features from the claimed combination may be deleted from the combination, and the claimed combination may be directed to a sub-combination or a variation of the sub-combination.

[0107] Similarly, while operations are depicted in a particular order in the drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired results. In addition, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0108] Only a few implementations and examples are described. Other implementations, enhancements, and variations may be made based on what is described and illustrated in this patent document.

[0109] CROSS-REFERENCE TO RELATED APPLICATIONS

[0110] This patent document claims priority to and the benefit of Korean Patent Application No. 10-2021-0100811 filed in the Korean Intellectual Property Office on July 30, 2021, which is hereby incorporated by reference in its entirety.

Claims

1. An image sensing device, comprising: a first active test block including a plurality of first active pixels, each of the plurality of first active pixels generating a first pixel signal corresponding to incident light, and a first heating element providing heat to the first active pixels at a first temperature; a second active test block including a plurality of second active pixels and a second heating element, each of the plurality of second active pixels generating a second pixel signal corresponding to the incident light, and the second heating element providing heat to the second active pixels at a second temperature higher than the first temperature; a first optical black test block including a plurality of first optical black pixels and a third heating element, each of the plurality of first optical black pixels generating a third pixel signal independent of the incident light, and the third heating element providing heat to the first optical black pixels at the first temperature; a second optical black test block including a plurality of second optical black pixels and a fourth heating element, each of the plurality of second optical black pixels generating a fourth pixel signal independent of the incident light, and the fourth heating element providing heat to the second optical black pixels at the second temperature; as well as A signal processing unit processes the first pixel signal to the fourth pixel signal.

2. The image sensing device according to claim 1, further comprising: an active pixel array comprising a plurality of active pixels, wherein the plurality of active pixels generate a fifth pixel signal corresponding to the incident light at a third temperature lower than the first temperature; as well as An optical black pixel array includes a plurality of optical black pixels, wherein the plurality of optical black pixels generate a sixth pixel signal that is independent of the incident light at the third temperature. 3 . The image sensing device according to claim 2 , further comprising a noise information memory storing information related to noise of the first to sixth pixel signals and generated based on the first to sixth pixel signals.

4. The image sensing device according to claim 3, wherein: The noise information memory stores noise information about colors associated with the first to third temperatures, respectively.

5. The image sensing device according to claim 4, wherein: The color includes at least one of red, green, blue, magenta, cyan or yellow.

6. The image sensing device according to claim 2, further comprising: a third active test block including a plurality of third active pixels each of which generates a seventh pixel signal corresponding to the incident light, and a fifth heating element that provides heat to the third active pixels at a fourth temperature higher than the second temperature; as well as A third optical black test block includes a plurality of third optical black pixels and a sixth heating element, each of the plurality of third optical black pixels generates an eighth pixel signal independent of the incident light, and the sixth heating element provides heat to the third optical black pixels at the fourth temperature.

7. The image sensing device according to claim 1, wherein: The first active test block includes a substrate including a doped region and a wiring element arranged below the doped region, the first active pixel is arranged on the substrate, and the first heating element is arranged between the doped region and the wiring element.

8. The image sensing device according to claim 1, wherein: The second active test block includes a substrate including a doped region and a wiring element arranged below the doped region, the second active pixel is arranged on the substrate, and the second heating element is arranged between the doped region and the wiring element.

9. The image sensing device according to claim 1, wherein: The first optical black test block includes a substrate including a doped region and a wiring element arranged below the doped region, the first optical black pixel is arranged on the substrate, and the third heating element is arranged between the doped region and the wiring element.

10. The image sensing device according to claim 1, wherein: The second optical black test block includes a substrate including a doped region and a wiring element arranged below the doped region, the second optical black pixel is arranged on the substrate, and the fourth heating element is arranged between the doped region and the wiring element.

11. An image sensing device, comprising: Multiple test pixel blocks heated to different temperatures simultaneously; as well as a signal processing unit that communicates with the plurality of test pixel blocks and obtains pixel signals of different colors based on dark current information associated with the temperature of the test pixel blocks, Wherein, each of the plurality of test pixel blocks comprises: a first block including a first optical black pixel and a first active pixel heated to a first temperature; and A second block includes second optical black pixels and second active pixels heated to a second temperature higher than the first temperature.

12. The image sensing device according to claim 11, wherein: The signal processing unit calculates background information based on pixel signals for different colors according to temperature.

13. The image sensing device according to claim 11, further comprising: an active pixel array including blocks of active pixels responsive to incident light; as well as An optical pixel array comprises an optical pixel block, wherein the optical pixel block comprises a light shielding structure, and the light shielding structure blocks the incident light from entering the optical pixel array.

14. The image sensing device according to claim 13, wherein: The signal processing unit calculates correction values ​​each of which allows a dark current of a corresponding optical pixel block to be brought to the same level as a dark noise component of a corresponding active pixel.

15. The image sensing device according to claim 14, wherein: The signal processing unit calculates a correction value for each color so that the correction values ​​of different colors are different from each other.

16. The image sensing device according to claim 14, wherein: Each correction value is calculated to represent a ratio between a dark current of a corresponding active pixel and a dark current of a corresponding optical pixel block.

17. A method of operating an image sensing device, the method comprising the steps of: heating a pixel array including active pixels and optical black pixels to a set temperature; heating a plurality of test pixel blocks to a temperature higher than the set temperature, each of the plurality of test pixel blocks including an optical black pixel and an active pixel; extracting pixel signals from the pixel array and the test pixel block according to temperature; as well as The pixel signal is used to obtain background information of the pixel array.

18. The method according to claim 17, wherein: The step of obtaining the base information includes: obtaining base information of different colors of the test pixel block according to temperature.

19. The method according to claim 17, further comprising the steps of: storing the substrate information; and The substrate information is used to calibrate a substrate of a chip including the pixel array.

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