Image Sensor

Abstract

To provide an image sensor that implements test patterns used to measure values of crosstalk components of pixels and can improve pixel performance by measuring and calculating values of crosstalk components of light blocking pixels.SOLUTION: The image sensor includes: a pixel array including a plurality of unit test patterns, each of which is used to measure values of crosstalk components of a plurality of light blocking pixels generated by a single open pixel; and a data output circuit 500. The data output circuit comprises: a storage unit 510 to store the measured values of crosstalk components measured respectively with the unit test patterns; a calculation unit 520 to calculate a crosstalk value about each target pixel by combining the values of crosstalk components stored in the storage unit; and a correction unit 530 to correct pixel data by reflecting in the pixel data the crosstalk value calculated by the calculation unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to image sensors and is a technique that allows pixel crosstalk to be estimated and corrected. [Background technology]

[0002] Generally, CMOS image sensors (CIS) made with CMOS process are rapidly expanding their market due to their advantages of low power consumption, low price and small size compared to other competing products. In particular, CIS image sensors are gradually expanding their application range to the video field, which requires high resolution and high frame rate, by improving the image quality that was relatively lacking compared to competing products.

[0003] Unlike solid-state imaging devices, CMOS image sensors must convert the analog signal (pixel signal) output from the pixel array into a digital signal. CMOS image sensors use a high-resolution analog-to-digital converter (ADC) inside to convert analog signals into digital signals.

[0004] The analog-to-digital converter performs correlated double sampling on the analog output voltage, which is the output signal of the pixel array, and stores the resulting voltage in a line memory. The sense amplifier senses, amplifies, and outputs the digital signal output from the line memory via the column line. Summary of the Invention [Problem to be solved by the invention]

[0005] An embodiment of the present invention provides an image sensor that implements a test pattern for measuring the value of the crosstalk component of a pixel, and measures and calculates the value of the crosstalk component of a light-shielded pixel, thereby enabling pixel performance to be improved. [Means for solving the problem]

[0006] An image sensor according to an embodiment of the present invention includes a pixel array including a plurality of unit test patterns that respectively measure values ​​of crosstalk components of a plurality of light-shielded pixels generated by one open pixel; a storage unit that stores values ​​of the crosstalk components measured by the plurality of unit test patterns; a calculation unit that calculates a crosstalk value for each target pixel by combining the crosstalk component values ​​stored in the storage unit; and a correction unit that corrects the pixel data by reflecting the crosstalk value calculated by the calculation unit in each pixel data. [Effects of the Invention]

[0007] The embodiments of the present invention provide the advantage of being able to improve performance by accurately determining the magnitude and directionality of the crosstalk component of a pixel and improving structural weaknesses of the pixel.

[0008] At the same time, the embodiments of the present invention are for illustrative purposes only, and those skilled in the art will be able to make various modifications, changes, substitutions and additions within the technical spirit and scope of the accompanying claims, and such modifications and variations should be considered to fall within the scope of the following claims. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of an image sensor according to an embodiment of the present invention; [Figure 2] FIG. 2 is a detailed configuration diagram of the data output circuit of FIG. [Figure 3] FIG. 2 is a diagram showing a unit test pattern in the image sensor of FIG. 1. [Figure 4a] FIG. 4 is a diagram for measuring the value of the crosstalk component of each pixel in the unit test pattern of FIG. 3. [Figure 4b] FIG. 4 is a diagram for measuring the value of the crosstalk component of each pixel in the unit test pattern of FIG. 3. [Figure 4c] This is a diagram for measuring the value of the crosstalk component of each pixel in the unit test pattern of FIG. 3. [Figure 4d] This is a diagram for measuring the value of the crosstalk component of each pixel in the unit test pattern of FIG. 3. [Figure 5] This is a cross-sectional view of the unit test pattern of FIG. 4b. [Figure 6] This is a cross-sectional view of the unit test pattern of FIG. 4b. [Figure 7] This is a diagram showing a test pattern for calculating the crosstalk value of each pixel in the image sensor of FIG. 1. [Figure 8a] This is a diagram for calculating the crosstalk value of a target pixel corresponding to the test pattern of FIG. 7. [Figure 8b] This is a diagram for calculating the crosstalk value of a target pixel corresponding to the test pattern of FIG. 7. [Figure 8c] This is a diagram for calculating the crosstalk value of a target pixel corresponding to the test pattern of FIG. 7. [Figure 8d] This is a diagram for calculating the crosstalk value of a target pixel corresponding to the test pattern of FIG. 7. [Figure 9] This is a diagram for explaining the position of the test pattern of FIG. 7. [Figure 10] This is a diagram for explaining the position of the test pattern of FIG. 7. <B

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing embodiments of the present invention, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" via another element therebetween. Spatial relative terms such as "below or beneath," "lower," "above," and "upper" may be used to easily describe the relationship between one element or component and another element or component as shown in the drawings. Spatial relative terms should be understood to include different orientations of elements during use or operation in addition to the orientation shown in the drawings. For example, if an element shown in the drawings is inverted, an element described as "below" or "beneath" another element may be placed "above" that other element.

[0011] Furthermore, when a part is described as "comprising" or "having" a certain element, this does not mean that other elements are excluded, but that the part may further include or have other elements, unless otherwise specified to the contrary. Furthermore, even if some elements are described in the singular throughout the specification, it should be understood that the present invention is not limited thereto, and that the element may consist of a plurality of elements.

[0012] FIG. 1 is a diagram showing the configuration of an image sensor according to an embodiment of the present invention.

[0013] Referring to FIG. 1, an image sensor 10 according to an embodiment of the present invention includes a pixel array 100, a row decoding circuit 200, a ramp signal generator 300, an analog-to-digital converter (ADC) 400, a data output circuit 500, and a control unit 600.

[0014] The pixel array 100 may include a plurality of pixels arranged in a matrix structure. The pixel array 100 converts incident optical signals into electrical signals and outputs pixel signals OUT to the analog-to-digital conversion circuit 400 via column lines. Here, the pixel array 100 may be driven by drive signals, such as a reset signal RX, a transmission signal TX, and a selection signal SX, applied from a row decoding circuit 200.

[0015] The row decoding circuit 200 selects a row line of the pixel array 100. That is, the row decoding circuit 200 selects pixels in the pixel array 100 for each row line in response to a control signal CON applied from the control unit 600, and controls the operation of the pixels.

[0016] The ramp signal generator 300 generates a ramp signal RAMP in response to a control signal CON applied from the control unit 600. The ramp signal RAMP generated by the ramp signal generator 300 is output to the analog-to-digital conversion circuit 400.

[0017] The analog-to-digital conversion circuit 400 converts the analog pixel signals OUT output from the pixel array 100 into digital signals. The analog-to-digital conversion circuit 400 may include a correlated double sampling (not shown) circuit that holds and samples signals received from the pixels of the pixel array 100.

[0018] The analog-to-digital conversion circuit 400 compares the pixel signal OUT output from the pixel array 100 with the value of the ramp signal RAMP applied from the ramp signal generator 300. The analog-to-digital conversion circuit 400 counts the reference clock CLK applied from the control unit 600 in accordance with the comparison value between the pixel signal OUT and the ramp signal RAMP, and outputs a column-based digital signal CNT.

[0019] The data output circuit 500 latches the digital signal CNT applied from the analog-to-digital conversion circuit 400. The data output circuit 500 then latches counting information and sequentially outputs pixel data DOUT in response to the output control signal OCON and the reference clock CLK. In an embodiment of the present invention, the pixel array 100 measures and calculates the value of the crosstalk component in each pixel, reflects the value in the pixel data DOUT, and outputs the pixel data DOUT in which the value of the crosstalk component has been corrected.

[0020] The control unit 600 controls the operations of the row decoding circuit 200, the ramp signal generator 300, the analog-to-digital conversion circuit 400, and the data output circuit 500. The control unit 600 may include a timing generator. That is, the control unit 600 can control various procedures from image sensing to outputting sensed image data according to time information.

[0021] To this end, the control unit 600 generates a control signal CON and outputs it to the row decoding circuit 200 and the ramp signal generator 300. The control unit 600 also generates a reference clock CLK and outputs it to the analog-to-digital conversion circuit 400. The control unit 600 also generates an output control signal OCON, a reference clock CLK, and a sensing enable signal SEN and outputs them to the data output circuit 500.

[0022] Fig. 2 is a detailed configuration diagram of the data output circuit 500 in Fig. 1. In the embodiment of Fig. 2, the function of measuring and calculating the value of the crosstalk component, among the functions of the data output circuit 500, will be mainly described.

[0023] Referring to FIG. 2, the data output circuit 500 includes a storage unit 510, a calculation unit 520, and a correction unit 530.

[0024] Here, the storage unit 510 stores the digital signal CNT applied from the analog-to-digital conversion circuit 400 in units of lines. The storage unit 510 can output data in units of columns in response to an output control signal OCON applied from the control unit 600.

[0025] In an embodiment of the present invention, the storage unit 510 can store the value of the crosstalk component of each pixel measured by each unit test pattern (for example, the unit test pattern of FIG. 3, which will be described later).

[0026] In an embodiment of the present invention, the storage unit 510 may be implemented as a line memory such as a static random access memory (SRAM) or a non-volatile memory such as a one-time programmable (OTP) memory, but is not limited thereto.

[0027] The calculation unit 520 may calculate crosstalk values ​​of neighboring pixels affecting each target pixel by adding up the crosstalk component values ​​stored in the storage unit 510. The target pixel may refer to a pixel that is the target for determining the crosstalk value. For example, the calculation unit 520 may calculate crosstalk values ​​affecting each neighboring pixel using the test pattern of FIG. 7, which will be described later. The crosstalk values ​​calculated by the calculation unit 520 may be used as values ​​for compensating pixel data in the effective pixel area.

[0028] The compensator 530 may reflect the crosstalk value calculated by the calculator 520 in the pixel data DOUT of each pixel and output pixel data with the crosstalk value compensated. That is, the compensator 530 may compensate for the crosstalk value for each target pixel by color.

[0029] For example, the correction unit 530 may correct pixel data by reflecting the crosstalk value of a red (R) pixel calculated by the calculation unit 520 to red pixel data. The correction unit 530 may correct pixel data by reflecting the crosstalk value of a blue (B) pixel calculated by the calculation unit 520 to blue pixel data. The correction unit 530 may correct pixel data by reflecting the crosstalk value of a green (Gr) pixel calculated by the calculation unit 520 to green pixel data. The correction unit 530 may correct pixel data by reflecting the crosstalk value of a green (Gb) pixel calculated by the calculation unit 520 to green pixel data.

[0030] Figure 3 is a diagram showing a unit test pattern (UTP) in the image sensor of Figure 1. In an embodiment of the present invention, the unit test pattern (UTP) may be provided in the pixel array 100 of Figure 1, and the location of the unit test pattern (UTP) will be described later.

[0031] 3, the unit test pattern (UTP) may include a plurality of pixels 110 arranged in a matrix structure. One pixel located in the center of the plurality of pixels 110 is implemented as an open pixel 111. Here, the open pixel 111 refers to a pixel having an open area so that incident light can be transmitted to a light receiving element.

[0032] The pixels surrounding the open pixel 111 (for example, the eight pixels in area (A)) (peripheral pixels) correspond to the light-shielded pixels 112. Here, the light-shielded pixels 112 refer to pixels having a shielded area that prevents incident light from being transmitted to the light-receiving element.

[0033] In addition, pixels arranged on the outer periphery of the light-shielding pixels 112 (e.g., 16 pixels outside the (A) region) correspond to protection pixels 113. Here, the protection pixels 113 may be arranged to surround the outer periphery of the (A) region in order to prevent crosstalk from entering the light-shielding pixels 112 from undesired directions.

[0034] 4a to 4d are diagrams for measuring the value of the crosstalk component in the unit test pattern (UTP) of FIG.

[0035] 4a to 4d, an embodiment of the present invention may implement four types of pixel patterns, namely, a red pixel (R), a blue pixel (B), a green pixel (Gb), and a green pixel (Gr), as open pixels 111. Here, the terms red, blue, green, etc. may refer to color filters written in the corresponding pixels.

[0036] In the embodiment of the present invention, the four types of pixel patterns are described as three types of colors, red, blue, and green (Gr, Gb), but this is only one embodiment and other colors may be used. Also, in the embodiment of the present invention, green (Gr) and green (Gb) are the same color, but are classified into different pixel patterns in order to measure the value of the crosstalk component of each pixel.

[0037] The open pixels 111 arranged in the central region of the unit test pattern (UTP) are not affected by crosstalk from the light-shielded pixels 112. In other words, since the light-shielded pixels 112 are pixels that are shielded from light, crosstalk components are not transmitted from the light-shielded pixels 112 to the open pixels 111.

[0038] Meanwhile, the shaded pixels 112 are affected by crosstalk due to light entering through the open pixels 111. Therefore, by measuring the crosstalk component value of each shaded pixel 112, the value of the crosstalk component that the open pixels 111 affect on the shaded pixels 112 can be detected.

[0039] 4a, the unit test pattern (UTP) in FIG. 4a shows a case where the open pixel 111 is a red pixel (R), which is not affected by crosstalk from the shaded pixel 112 (a red pixel not affected by crosstalk is defined as oR).

[0040] For example, eight light-shielding pixels 112 such as a blue pixel (B), a green pixel (Gb), a blue pixel (B), a green pixel (Gr), a green pixel (Gr), a blue pixel (B), a green pixel (Gb), and a blue pixel (B) may be arranged in the peripheral (A) area of ​​the red pixel (oR).

[0041] That is, the value of the crosstalk component (wRtoB) that the blue pixel (B) located at the upper left of the open pixel 111 receives from the red pixel (oR) can be measured. The value of the crosstalk component (wRtoGb) that the green pixel (Gb) located at the top of the open pixel 111 receives from the red pixel (oR) can be measured. The value of the crosstalk component (wRtoB) that the blue pixel (B) located at the upper right of the open pixel 111 receives from the red pixel (oR) can be measured.

[0042] The value of the crosstalk component (wRtoGr) that the green pixel (Gr) located to the left of the open pixel 111 receives from the red pixel (oR) can be measured. The value of the crosstalk component (wRtoGr) that the green pixel (Gr) located to the right of the open pixel 111 receives from the red pixel (oR) can be measured.

[0043] Then, the value of the crosstalk component (wRtoB) that the blue pixel (B) located at the bottom left of the open pixel 111 receives from the red pixel (oR) can be measured. The value of the crosstalk component (wRtoGb) that the green pixel (Gb) located at the bottom of the open pixel 111 receives from the red pixel (oR) can be measured. The value of the crosstalk component (wRtoB) that the blue pixel (B) located at the bottom right of the open pixel 111 receives from the red pixel (oR) can be measured.

[0044] 4b, the unit test pattern (UTP) of FIG. 4b shows a case where the open pixel 111 is a green pixel (Gr), which is not affected by crosstalk from the shaded pixel 112 (a green pixel not affected by crosstalk is defined as oGr).

[0045] For example, eight light-shielding pixels 112 such as a green pixel (Gb), a blue pixel (B), a green pixel (Gb), a red pixel (R), a red pixel (R), a green pixel (Gb), a blue pixel (B), and a green pixel (Gb) may be arranged in the peripheral (A) area of ​​the green pixel (oGr).

[0046] That is, the value of the crosstalk component (wGrtoGb) that the green pixel (Gb) located at the upper left of the open pixel 111 receives from the green pixel (oGr) can be measured. The value of the crosstalk component (wGrtoB) that the blue pixel (B) located at the top of the open pixel 111 receives from the green pixel (oGr) can be measured. The value of the crosstalk component (wGrtoGb) that the green pixel (Gb) located at the upper right of the open pixel 111 receives from the green pixel (oGr) can be measured.

[0047] The value of the crosstalk component (wGrtoR) that the red pixel (R) located to the left of the open pixel 111 receives from the green pixel (oGr) can be measured. The value of the crosstalk component (wGrtoR) that the red pixel (R) located to the right of the open pixel 111 receives from the green pixel (oGr) can be measured.

[0048] Then, the value of the crosstalk component (wGrtoGb) that the green pixel (Gb) located at the lower left of the open pixel 111 receives from the green pixel (oGr) can be measured. The value of the crosstalk component (wGrtoB) that the blue pixel (B) located at the lower part of the open pixel 111 receives from the green pixel (oGr) can be measured. The value of the crosstalk component (wGrtoGb) that the green pixel (Gb) located at the lower right of the open pixel 111 receives from the green pixel (oGr) can be measured.

[0049] Referring to Figure 4c, the unit test pattern (UTP) of Figure 4c shows a case where the open pixel 111 is a blue pixel (B), which is not affected by crosstalk from the shaded pixel 112 (the blue pixel not affected by crosstalk is defined as oB).

[0050] For example, eight light-shielding pixels 112 such as a red pixel (R), a green pixel (Gr), a red pixel (R), a green pixel (Gb), a green pixel (Gb), a red pixel (R), a green pixel (Gr), and a red pixel (R) may be arranged in the peripheral (A) area of ​​the blue pixel (oB).

[0051] That is, the value of the crosstalk component (wBtoR) that the red pixel (R) located at the upper left of the open pixel 111 receives from the blue pixel (oB) can be measured. The value of the crosstalk component (wBtoGr) that the green pixel (Gr) located at the top of the open pixel 111 receives from the blue pixel (oB) can be measured. The value of the crosstalk component (wBtoR) that the red pixel (R) located at the upper right of the open pixel 111 receives from the blue pixel (oB) can be measured.

[0052] The value of the crosstalk component (wBtoGb) that the green pixel (Gb) located to the left of the open pixel 111 receives from the blue pixel (oB) can be measured. The value of the crosstalk component (wBtoGb) that the green pixel (Gb) located to the right of the open pixel 111 receives from the blue pixel (oB) can be measured.

[0053] Then, the value of the crosstalk component (wBtoR) that the red pixel (R) located at the bottom left of the open pixel 111 receives from the blue pixel (oB) can be measured. The value of the crosstalk component (wBtoGr) that the green pixel (Gr) located at the bottom of the open pixel 111 receives from the blue pixel (oB) can be measured. The value of the crosstalk component (wBtoR) that the red pixel (R) located at the bottom right of the open pixel 111 receives from the blue pixel (oB) can be measured.

[0054] Referring to Figure 4d, the unit test pattern (UTP) of Figure 4d shows a case where the open pixel 111 is a green pixel (Gb), which is not affected by crosstalk from the shaded pixel 112 (green pixels not affected by crosstalk are defined as oGb).

[0055] For example, eight light-shielding pixels 112 such as a green pixel (Gr), a red pixel (R), a green pixel (Gr), a blue pixel (B), a blue pixel (B), a green pixel (Gr), a red pixel (R), and a green pixel (Gr) may be arranged in the peripheral (A) area of ​​the green pixel (oGb).

[0056] That is, the value of the crosstalk component (wGbtoGr) that the green pixel (Gr) located at the upper left of the open pixel 111 receives from the green pixel (oGb) can be measured. The value of the crosstalk component (wGbtoR) that the red pixel (R) located at the top of the open pixel 111 receives from the green pixel (oGb) can be measured. The value of the crosstalk component (wGbtoGr) that the green pixel (Gr) located at the upper right of the open pixel 111 receives from the green pixel (oGb) can be measured.

[0057] The value of the crosstalk component (wGbtoB) received by the blue pixel (B) located to the left of the open pixel 111 from the green pixel (oGb) can be measured. The value of the crosstalk component (wGbtoB) received by the blue pixel (B) located to the right of the open pixel 111 from the green pixel (oGb) can be measured.

[0058] That is, the value of the crosstalk component (wGbtoGr) that the green pixel (Gr) located at the bottom left of the open pixel 111 receives from the green pixel (oGb) can be measured. The value of the crosstalk component (wGbtoR) that the red pixel (R) located at the bottom of the open pixel 111 receives from the green pixel (oGb) can be measured. The value of the crosstalk component (wGbtoGr) that the green pixel (Gr) located at the bottom right of the open pixel 111 receives from the green pixel (oGb) can be measured.

[0059] 5 and 6 are cross-sectional views of the unit test pattern (UTP) of FIG. 4b. The examples of FIG. 5 and FIG. 6 may be cross-sectional views of the unit test pattern (UTP) of FIG. 4b cut in the (B)-(B') direction. The embodiment of FIG. 4 may show a dark state in which no light is irradiated, and the embodiment of FIG. 5 may show a white state in which light is irradiated.

[0060] 5, a unit test pattern (UTP) may have a plurality of unit pixel regions formed on a substrate 120. Light receiving elements 121a to 121c may be formed on the substrate 120 corresponding to each unit pixel region. The light receiving elements 121a to 121c may be separated by an element isolation layer (not shown). Each of the light receiving elements 121a to 121c may include a photodiode (PD). Here, the photodiode may generate photocharges using received light.

[0061] An interlayer insulating film 123 including a shielding layer 122 is formed on the substrate 120. The shielding layer 122 may be implemented as a metal wiring for blocking incident light. That is, the shielding layer 122 can block light incident from the outside through the color filters 124 and 126 from being transmitted to the light receiving elements 121a and 121c.

[0062] A plurality of color filters 124 to 126 corresponding to unit pixel regions may be included on the interlayer insulating film 123. The plurality of color filters 124 to 126 are for obtaining a color image and are formed one for each unit pixel region to separate colors from incident light.

[0063] Here, the color filters 124 to 126 represent different colors, and may be composed of three types of colors: red (R), green (G), and blue (B). For example, the color filters 124 to 126 may include a red (R) color filter 124, a green (G) color filter 125, and a blue (B) color filter 126. The red (R) color filter 124 passes only red light from incident light (e.g., visible light). The green (G) color filter 125 passes only green light from incident light. The blue (B) color filter 126 passes only blue light from incident light.

[0064] Microlenses 128 are formed on the color filters 124 to 126 in correspondence with the light receiving elements 121a to 121c, respectively. The microlenses 128 can condense light onto each unit pixel area. Here, the microlenses 128 may be embodied in a hemispherical shape.

[0065] 5, it may be shown that the green (G) color filter 125 is embodied as an open pixel 111. When the green (G) color filter 125 is embodied as an open pixel 111, a shield layer 122 is not formed below the green (G) color filter 125. Meanwhile, a shield layer 122 is formed below each of the red (R) color filter 124 and the blue (B) color filter 126. That is, the red (R) color filter 124 and the blue (B) color filter 126 may have the shield layer 122 formed thereon to block light and measure the value of the crosstalk component of the light-shielded pixel 112.

[0066] 6, when the unit test pattern (UTP) is in a white state, light may be irradiated onto any of the red (R) color filter 124, green (G) color filter 125, and blue (B) color filter 126. Each pixel receives all the light corresponding to the red (R), green (G), and blue (B) values, but only senses the value (R value, G value, or B value) of the specific color corresponding to the color filters 124 to 126 written in each pixel.

[0067] 6, among the three color filters 124-126, light passes through the green (G) color filter 125, which is an open pixel 111, and can be transmitted to the light receiving element 121b (light-transmitting region). That is, because the shield layer 122 is not formed below the green (G) color filter 125, incident light passes through the interlayer insulating film 123 and reaches the light receiving element 121b. On the other hand, among the three color filters 124-126, the red (R) color filter 124 and blue (B) color filter 126, which are light-shielding pixels 112, are shielded by the shield layer 122, and light is not transmitted to the light receiving elements 121a and 121c (shielding region).

[0068] In Fig. 6, (C) solid lines indicate that light is irradiated in the optical axis direction. (D) diagonal lines indicate that crosstalk occurs in the diagonal (spatial) direction between adjacent unit pixel regions. (E) indicates that crosstalk occurs in the vertical (spectral) direction in which light is irradiated at the vertex of the microlens 128. (F) indicates crosstalk that occurs between the light receiving elements 121a to 121c due to an electric field. (G) indicates fixed pattern noise (FPN) that may occur between each pixel.

[0069] Each unit pixel included in the pixel array 100 should receive only light components of its own color. However, in practice, since the isolation between adjacent unit pixels is not perfectly realized, crosstalk occurs between the unit pixels.

[0070] Such crosstalk phenomenon transmits unwanted light components to adjacent unit pixels, thereby reducing the color discrimination ability of the unit pixels. Such reduction in the color discrimination ability of the unit pixels may reduce the sensing sensitivity of the entire image sensor, resulting in a degradation of image quality. Furthermore, unwanted noise exists between each pixel, making it difficult to distinguish between diagonal and vertical crosstalk, and thus making it impossible to determine the direction of the crosstalk.

[0071] 6, in an embodiment of the present invention, only one color filter 125 is opened, and the other color filters 124 and 126 for which crosstalk components are to be measured are shielded from light by a shield layer 122. In this way, even though the red (R) color filter 124 and blue (B) color filter 126 are shielded from light by the shield layer 122, the crosstalk component values ​​are transmitted from the color filter 125 to the light receiving elements 121a and 121c.

[0072] Since pixel crosstalk is one of the important indicators for improving pixel performance, an accurate evaluation method is required. For this reason, an embodiment of the present invention implements open pixel patterns for four color patterns (R, Gr, Gb, B). Then, the value of the crosstalk component, in which light applied from one open pixel 111 is transmitted to a shaded pixel 112, can be measured.

[0073] That is, it is possible to obtain the values ​​of the crosstalk components occurring in the light-shielded pixels 112 in eight directions affected by one open pixel 111. Therefore, it is possible to find unit pixels whose color discrimination ability has been reduced due to crosstalk, improve the characteristics of the found unit pixels, and increase the sensing strength of the entire image sensor.

[0074] FIG. 7 is a diagram showing a test pattern (TP) for calculating the crosstalk value of each pixel in the image sensor of FIG.

[0075] 7, the test pattern (TP) may include a plurality of pixels 110 arranged in a matrix structure. For example, the plurality of pixels 110 may be implemented as 72 pixels in total, with 8 pixels arranged in the row direction and 9 pixels arranged in the column direction.

[0076] The test pattern (TP) may be implemented by combining four types of unit test pixels (UTP) into one test pattern (TP) to realize a plurality of pixel group patterns 131 to 134 in order to calculate the values ​​of the crosstalk components measured in Figures 4a to 4d. The plurality of pixel groups 131 to 134 may be arranged adjacently in the horizontal or vertical direction.

[0077] In the plurality of pixels 110, pixel group 131 may have red pixels (R) implemented as open pixels 111. Pixel group 132 may have green pixels (Gr) implemented as open pixels 111. Pixel group 133 may have blue pixels (B) implemented as open pixels 111. Pixel group 134 may have green pixels (Gb) implemented as open pixels 111.

[0078] 8a to 8d are diagrams for calculating the crosstalk value of a target pixel corresponding to the test pattern (TP) of FIG.

[0079] The crosstalk component values ​​generated in each direction from the pixel structure of the effective pixel area are the sum of the crosstalk component values ​​measured in the unit test patterns (UTP) of Figures 4a to 4d. Therefore, the crosstalk component values ​​measured in the test patterns (TP) can be remapped as shown in Figures 8a to 8d to calculate the crosstalk value (Xtalk) for each target pixel. Here, remapping may mean recombining the crosstalk component values ​​according to the test patterns.

[0080] 8a, the crosstalk component value generated in the effective pixel area is the sum of the crosstalk components generated in the eight pixels surrounding the red pixel (R). The crosstalk value (Xtalk@R) that the red pixel (R) receives from the surrounding pixels may be calculated as follows:

number

[0081] Referring to Equation 1 above, the crosstalk value (Xtalk@R) can be calculated by adding the crosstalk component values ​​transmitted from the eight surrounding pixels measured in the unit test pattern (UTP) of Figure 4a. Then, to remove the fixed pattern noise contained in the pixel itself, the value (dR) of the red pixel (R) in the dark state is subtracted as shown in Figure 5.

[0082] 8b, the crosstalk component value generated in the effective pixel area is the sum of the crosstalk components generated in the eight pixels surrounding the green pixel (Gr). The crosstalk value (Xtalk@Gr) received by the green pixel (Gr) from the surrounding pixels may be calculated as follows:

number

[0083] Referring to Equation 2 above, the crosstalk value (Xtalk@Gr) can be calculated by adding the crosstalk component values ​​transmitted from the eight surrounding pixels measured in the unit test pattern (UTP) of Figure 4b. Then, to remove the fixed pattern noise contained in the pixel itself, the value (dGr) of the green pixel (Gr) in the dark state is subtracted as shown in Figure 5.

[0084] 8c, the crosstalk component value generated in the effective pixel area is the sum of the crosstalk components generated in the eight pixels surrounding the blue pixel (B). The crosstalk value (Xtalk@B) received by the blue pixel (B) from the surrounding pixels may be calculated as follows:

number

[0085] Referring to Equation 3 above, the crosstalk value (Xtalk@B) can be calculated by adding the crosstalk component values ​​transmitted from the eight surrounding pixels measured in the unit test pattern (UTP) of Figure 4c. Then, to remove the fixed pattern noise contained in the pixel itself, the value (dB) of the blue pixel (B) in the dark state is subtracted as shown in Figure 5.

[0086] 8d, the crosstalk component value generated in the effective pixel area is the sum of the crosstalk components generated in the eight pixels surrounding the green pixel (Gb). The crosstalk value (Xtalk@Gb) received by the green pixel (Gb) from the surrounding pixels may be calculated as follows:

number

[0087] Referring to Equation 4 above, the crosstalk value (Xtalk@Gb) can be calculated by adding the crosstalk component values ​​transmitted from the eight surrounding pixels measured in the unit test pattern (UTP) of Figure 4d. Then, to remove the fixed pattern noise contained in the pixel itself, the value (dGb) of the green pixel (Gb) in the dark state is subtracted as shown in Figure 5.

[0088] 9 and 10 are diagrams for explaining the position of the test pattern (TP) in FIG.

[0089] 9, the test pattern (TP) may be formed in units of a test pattern set (TPS) in which a plurality of test patterns are adjacently arranged. The test pattern set (TPS) may be arranged in an open dummy area on the periphery of the effective pixel area of ​​the pixel array 100. For example, the test pattern sets (TPS) may be arranged in the top center (TC), top left (TL), top right (TR), center left (CL), center right (CR), bottom center (BC), bottom left (BL), and bottom right (BR) of the effective pixel area of ​​the pixel array 100.

[0090] Meanwhile, referring to the embodiment of FIG. 10, a plurality of test patterns (TP) may be arranged in the entire area including the center area in addition to the effective pixel area and the open dummy area of ​​the pixel array 100.

[0091] Those skilled in the art to which the present invention pertains should understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof, and therefore the above-described embodiments should be understood to be illustrative in all respects and not limiting. The scope of the present invention is defined by the claims below rather than the detailed description, and all modifications and variations derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. a pixel array including a test pattern used for measuring values ​​of crosstalk components of a plurality of light-shielded pixels caused by one open pixel; a storage unit for storing values ​​of the crosstalk components measured by the test patterns; a calculation unit for calculating a crosstalk value for each target pixel by combining the crosstalk component values ​​stored in the storage unit; a correction unit that corrects each pixel data by reflecting the crosstalk value calculated by the calculation unit in the pixel data, The test pattern is a first unit test pattern including a first open pixel embodied as a pixel of a first color and a plurality of first light-shielding pixels surrounding the first open pixel; a second unit test pattern including a second open pixel embodied as a pixel of a second color and a plurality of second light-shielding pixels surrounding the second open pixel, the second unit test pattern being disposed adjacent to the first unit test pattern in a first direction; a third unit test pattern including a third open pixel embodied as a pixel of a third color and a plurality of third light-shielding pixels surrounding the third open pixel, the third unit test pattern being disposed adjacent to the first unit test pattern in a second direction; a fourth open pixel embodied as a pixel of a fourth color and a plurality of fourth light-shielding pixels surrounding the fourth open pixel, the fourth unit test pattern being adjacent to the second unit test pattern in a second direction; At least some of the first light-shielding pixels are disposed in upper and lower row lines immediately adjacent to the first open pixel, at least some of the second light-shielding pixels are disposed in upper and lower row lines immediately adjacent to the second open pixel, at least some of the third light-shielding pixels are disposed in upper and lower row lines immediately adjacent to the third open pixel, and at least some of the fourth light-shielding pixels are disposed in upper and lower row lines immediately adjacent to the fourth open pixel; an upper row line of the first open pixel, an upper row line of the second open pixel, an upper row line of the third open pixel, and an upper row line of the fourth open pixel are not adjacent to each other in the same corresponding row line; the first open pixel, the second open pixel, the third open pixel, and the fourth open pixel are arranged in different row lines; The first color, the second color, and the third color are different from each other.

2. Each of the first unit test pattern to the fourth unit test pattern is A substrate including a plurality of unit pixel regions; a plurality of color filters each formed on the substrate in correspondence with a unit pixel area; 2. The image sensor of claim 1, further comprising: a shield layer formed under some of the plurality of color filters to block light entering through the some of the color filters.

3. The image sensor of claim 2 , wherein light incident on the plurality of light-shielding pixels is blocked by the shield layer.

4. Each of the first unit test pattern to the fourth unit test pattern is The image sensor of claim 1 , further comprising a plurality of protection pixels disposed around the plurality of light blocking pixels.

5. The image sensor according to claim 4 , wherein the protection pixels are arranged on a plane in a manner surrounding the light-shielding pixels.

6. 2. The image sensor of claim 1, wherein light incident on one open pixel is transmitted to a lower light receiving element through one color filter.

7. Each of the first unit test pattern to the fourth unit test pattern is 2. The image sensor of claim 1, further comprising: measuring a value of a crosstalk component of each of the light-shielded pixels in response to a value of a crosstalk component generated in the one open pixel when light is incident on the one open pixel.

8. The one open pixel is 2. The image sensor of claim 1, comprising one of a red pixel, a green pixel, and a blue pixel.

9. The test pattern is The image sensor according to claim 1 , wherein the pixel array is formed in an open dummy area disposed on the periphery of an effective pixel area of ​​the pixel array.

10. The test pattern is 10. The image sensor of claim 9, wherein the pixel electrode is disposed at least one of the top center, top left, top right, center left, center right, bottom center, bottom left, and bottom right of the effective pixel area on a plane.

11. The test pattern is 2. The image sensor according to claim 1, wherein the plurality of test patterns are formed as a unit of test pattern sets arranged adjacent to each other.

12. The test pattern is The image sensor of claim 1 , wherein the pixel array is formed over an entire area including a central area of ​​the pixel array.

13. The calculation unit is 2. The image sensor of claim 1, wherein the crosstalk value of the pixel is calculated by adding up the crosstalk component values ​​of the multiple surrounding pixels surrounding the one target pixel and subtracting the value of the one target pixel in a dark state.

14. 14. The image sensor of claim 13, wherein the value of the one target pixel in the dark state is fixed pattern noise of the one target pixel.

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