Image sensor and imaging apparatus

Abstract

The application provides an image sensor and an imaging device. The image sensor comprises a plurality of pixel units; the plurality of pixel units are divided into a first pixel group, a second pixel group, a third pixel group and a fourth pixel group arranged in an array; the second pixel group and the third pixel group are diagonally arranged; the first pixel group comprises a first pixel unit and a fourth pixel unit; the second pixel group comprises a second pixel unit and a fourth pixel unit; the third pixel group comprises a second pixel unit and a fourth pixel unit; the fourth pixel group comprises a third pixel unit and a fourth pixel unit; the first pixel unit, the second pixel unit and the third pixel unit are monochrome pixel units for receiving light of different colors; and the fourth pixel unit is a white pixel unit for receiving white light. In the above technical solution, the white pixel unit is introduced into each pixel group, and the sensitivity of the image sensor is improved through the white pixel unit, thereby improving the resolving power and signal-to-noise ratio of the image.

Description

Technical Field

[0001] This application relates to the field of imaging technology, and in particular to an image sensor and imaging device. Background Technology

[0002] Traditional pixel arrays in image sensors typically use red, green, and blue pixels arranged in an alternating pattern. However, with the development of imaging technology, a new pixel arrangement technique has emerged. This technique combines four adjacent pixels of the same color to form a pixel that is four times larger than the original pixel, hence it is also known as "four-pixel binning" technology.

[0003] The "four-pixel binning" technology has been widely used in mobile phone cameras in recent years. By acquiring a pixel that is four times larger than the original pixel, the sensitivity in low-light shooting environments can be improved, and the signal-to-noise ratio of the image can be increased, ultimately producing a bright and low-noise image.

[0004] Image sensors employing a "four-pixel binning" arrangement are currently widely used. In the default 10-megapixel output mode, four-pixel binning simultaneously samples four adjacent pixels of the same color, resulting in a 1 / 4 resolution image of 10 megapixels with a single pixel size of 2µm, achieving high light sensitivity within a small-sized, high-pixel image sensor. In the 40-megapixel full-resolution output mode, a remosaic algorithm is used to rearrange the pixels into a traditional pixel array format, outputting a high-resolution 40-megapixel image after image signal processing.

[0005] However, the current "four-pixel-in-one" array sorting of pixel arrays, for 1 / 4 resolution output images, although it has a significant improvement in signal-to-noise ratio compared with the traditional pixel array output images, its resolution is significantly reduced. And for full pixel output results, compared with the results of the traditional pixel array format that does not require misaligned pixels, the resolution is reduced. Summary of the Invention

[0006] This application provides an image sensor and imaging device for improving the resolution of the image sensor and enhancing its imaging performance.

[0007] In a first aspect, an image sensor is provided, comprising multiple pixel units; the multiple pixel units are divided into a first pixel group, a second pixel group, a third pixel group, and a fourth pixel group arranged in an array, with the second pixel group and the third pixel group diagonally arranged; wherein, the first pixel group includes a first pixel unit and a fourth pixel unit; the second pixel group includes a second pixel unit and a fourth pixel unit; the third pixel group includes a second pixel unit and a fourth pixel unit; the fourth pixel group includes a third pixel unit and a fourth pixel unit; wherein the third pixel unit is a monochromatic pixel unit used to receive different colors of light; and the fourth pixel unit is a white pixel unit that receives white light. In the above technical solution, by introducing white pixel units in each pixel group, the sensitivity of the image sensor is improved, thereby enhancing the image resolution and signal-to-noise ratio.

[0008] In one specific implementation, each of the first, second, third, and fourth pixel groups includes four pixel units arranged in an array; wherein, in each pixel group, at least one pixel unit is a white pixel unit; the remaining pixel units are monochromatic pixel units used to receive light of the same color. Different proportions of white pixel units can be selected within the pixel groups.

[0009] In one specific implementation, each pixel group includes three monochrome pixel units for receiving light of the same color and one white pixel unit. By employing one white unit and three monochrome pixel units, the sensitivity of the image sensor is improved while ensuring the acquisition of color information.

[0010] In one specific implementation, in each pair of adjacent pixel groups, there are other pixel units spaced apart between the white pixel unit located in one pixel group and the white pixel unit located in the other pixel group.

[0011] In one specific implementation, each pixel group includes two monochrome pixel units for receiving light of the same color and two white pixel units; wherein the two white pixel units are arranged diagonally.

[0012] In one specific implementation, the size of the fourth pixel unit is smaller than the sizes of the first, second, and third pixel units. By reducing the size of the white pixel unit, the exposure of the white pixel is reduced, thereby reducing the sensitivity of the white pixel unit, delaying the saturation time of the white pixel unit, allowing other pixel units to be more fully exposed, and increasing the image color signal.

[0013] In one specific implementation, the white pixel unit is wrapped with a metal shielding layer; the size of the white pixel unit after being wrapped with the metal shielding layer is equal to the size of the monochrome pixel unit. By setting the metal shielding layer, the size of the fourth pixel unit is reduced.

[0014] In one specific implementation, the image sensor further includes a light-filtering module disposed on the light-incident side of the plurality of pixel units. The light-filtering module filters out stray light.

[0015] In one specific implementation, the image sensor further includes a lens for focusing light, the lens being located on the light-incident side of the plurality of pixel units. The light-focusing lens increases the amount of light entering the sensor.

[0016] In one specific implementation, a filter module is also included on the light-incident side of the plurality of pixel units. This reduces stray light interference and improves imaging performance.

[0017] In one specific implementation, the filter module is a dual-passband filter module, which allows both white light and infrared light to pass through. This reduces stray light interference and improves imaging performance.

[0018] In one specific implementation, the monochrome pixel unit is coated with a filter layer that blocks infrared light; the white pixel unit receives both white light and infrared light. Infrared light is used to increase brightness, thereby improving the imaging effect.

[0019] In one specific implementation scheme, the system further includes an image processing module. This module performs interpolation calculations based on the first color light received by the monochrome pixel units in each pixel group to obtain the second color light corresponding to the pixel unit at the location of the white pixel unit in that pixel group. It then performs pixel binning on the four pixel units in each pixel group based on the first and second color light to obtain a pixel-binded image. It also obtains brightness information based on the white light received by the white pixel units in each pixel group. Finally, it combines the pixel-binded image formed by each pixel group with the corresponding brightness information of that pixel group to obtain a 1 / 4 resolution image. This results in a high-quality 1 / 4 resolution image.

[0020] In one specific implementation, the image processing module is further configured to demosaic the pixel array to obtain an image; perform interpolation on the white light received by each white pixel unit to obtain the brightness information corresponding to each pixel unit; and combine the demosaic image with the brightness information corresponding to each pixel unit to obtain a full-resolution image. This results in a high-quality, full-resolution image.

[0021] Secondly, an imaging device is provided, comprising a housing and an image sensor as described in any of the above-mentioned embodiments disposed within the housing. In the above-described technical solution, by introducing white pixel units in each pixel group, the sensitivity of the image sensor is improved through the white pixel units, thereby enhancing the image resolution and signal-to-noise ratio. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the application scenario of the image sensor provided in the embodiments of this application;

[0023] Figure 2 This is a schematic diagram of the pixel array of an image sensor in the prior art;

[0024] Figure 3 This is a schematic diagram of the structure of the image sensor provided in the embodiments of this application;

[0025] Figure 4 This is a schematic diagram of a pixel array provided in an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of light illuminating a pixel array according to an embodiment of this application;

[0027] Figure 6 A circuit diagram of the color information acquisition unit provided in the embodiments of this application;

[0028] Figure 7 A circuit diagram of the brightness information acquisition unit provided in the embodiments of this application;

[0029] Figure 8 A flowchart illustrating how an image sensor, as provided in an embodiment of this application, forms a high-quality image at 1 / 4 resolution.

[0030] Figure 9 A flowchart illustrating how an image sensor, as provided in an embodiment of this application, forms a high-quality image at full resolution.

[0031] Figure 10 This is a schematic diagram illustrating the resolution of a 1 / 4 resolution image from an existing image sensor.

[0032] Figure 11 A schematic diagram illustrating the resolution of a 1 / 4 resolution image from an image sensor provided in an embodiment of this application;

[0033] Figure 12 A schematic diagram illustrating the full-resolution capabilities of image sensors in the prior art;

[0034] Figure 13 A schematic diagram illustrating the full-resolution image processing capability of the image sensor provided in this application embodiment;

[0035] Figure 14 This is another schematic diagram of a pixel array provided in an embodiment of this application;

[0036] Figure 15 This is another schematic diagram of a pixel array provided in an embodiment of this application;

[0037] Figure 16 This is a schematic diagram of light illuminating a pixel array according to an embodiment of this application;

[0038] Figure 17 for Figure 5 The received curve of the pixel array shown;

[0039] Figure 18 for Figure 15 The received curve of the pixel array shown;

[0040] Figure 19 A schematic diagram illustrating the principle of improving resolution using a pixel array, as provided in an embodiment of this application.

[0041] Figure 20 This is another schematic diagram of a pixel array provided in an embodiment of this application;

[0042] Figure 21 A light incident pattern of another pixel array provided in an embodiment of this application;

[0043] Figure 22 This is a schematic diagram of another image sensor structure provided in an embodiment of this application;

[0044] Figure 23 This is a schematic diagram of another pixel array provided in an embodiment of this application. Detailed Implementation

[0045] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0046] First, the application scenarios of the image sensor provided in this application embodiment are explained. The image sensor provided in this application embodiment is applied in electronic devices, such as mobile phones, tablets, wearable electronic devices, and other common devices with camera functions. Of course, it can also be applied to other types of electronic devices with camera functions. Figure 1 As shown in the illustration, when the image sensor 2 provided in this embodiment is applied within a mobile terminal, the mobile terminal includes a housing 1 and the image sensor 2 disposed within the housing 1. The image sensor 2 is disposed on a motherboard 3 and is electrically connected to the motherboard 3. When light from a target object enters the image sensor 2, the optical signal can be converted into an electrical signal by the image sensor 2, and imaging processing can be performed.

[0047] Image sensors in existing technologies, such as Figure 2As shown, the image sensor includes multiple pixel units arranged in an array. Taking a 4x4 array as an example, the multiple pixel units are divided into four pixel groups: a first pixel group 4, a second pixel group 5, a third pixel group 6, and a fourth pixel group 7. Specifically, the first pixel group 4 includes four pixel units for receiving red light (represented by R in the figure), the second pixel group 5 includes four pixel units for receiving green light (represented by Gr in the figure), the third pixel group 6 includes four pixel units for receiving green light (represented by Gb in the figure), and the fourth pixel group 7 includes four pixel units for receiving blue light (represented by B in the figure). However, when using the above technical solution, each pixel group in the existing image sensor only collects monochromatic light (red, green, or blue light) from the target object. This results in poor photosensitivity of the image sensor in environments with low white light illumination, thereby reducing image quality. Therefore, this application provides an image sensor, which will be described in detail below with reference to specific drawings and embodiments.

[0048] refer to Figure 3 , Figure 3 A schematic diagram of the structure of an image sensor provided in an embodiment of this application is shown. The image sensor provided in this embodiment includes a lens 10, a pixel array 20, and an image processing module 30 arranged along the optical path. The pixel array 20 includes a color filter layer 21 and an image acquisition module 22. Light rays emanating from the target object pass sequentially through the lens 10 and the color filter layer 21 before illuminating the image acquisition module 22. The image acquisition module 22 converts the optical signal into a digital signal, and the image processing module 30 performs imaging processing based on the digital signal from the image acquisition module 22 to form an image.

[0049] It should be understood that the lens 10 described above is an optional module structure. When setting up an image sensor, the lens 10 can be selectively set according to actual needs, and no specific limitation is made in the embodiments of this application.

[0050] Please refer to the above. Figure 4 The pixel array contains multiple pixel units arranged in M ​​rows and N columns, where M and N are both positive integers greater than 2. These pixel units include different types of pixel units; for example, they can be categorized as first pixel units, second pixel units, third pixel units, and fourth pixel units. There are multiple first pixel units, second pixel units, third pixel units, and fourth pixel units. The first pixel units, second pixel units, third pixel units, and fourth pixel units have the same size.

[0051] The first pixel unit, the second pixel unit, and the third pixel unit are monochromatic pixel units capable of receiving different colors of light, for transmitting monochromatic light (red light, green light, and blue light) from the target object. For example, the first pixel unit, the second pixel unit, and the third pixel unit can be a red pixel unit receiving red light, a green pixel unit receiving green light, and a blue pixel unit receiving blue light, respectively. Alternatively, the first pixel unit, the second pixel unit, and the third pixel unit can be a cyan pixel unit, a magenta pixel unit, and a yellow pixel unit, respectively. Of course, the above-described first pixel unit, second pixel unit, and third pixel unit are merely two specific examples; the first pixel unit, second pixel unit, and third pixel unit provided in this application embodiment can also receive other colors of light according to imaging requirements.

[0052] The fourth pixel unit is a white light pixel unit that can receive white light. When white light shines on the fourth pixel unit, it can be received by the image acquisition module in the fourth pixel unit.

[0053] Continue to refer to Figure 4 Taking a 4x4 array as an example, multiple pixel units are divided into four pixel groups: the first pixel group 23, the second pixel group 24, the third pixel group 25, and the fourth pixel group 26. These four pixel groups are arranged in an array. The first pixel group 23 and the second pixel group 24 are in the same row, the third pixel group 25 and the fourth pixel group 26 are in the same row, and the third pixel group 25 and the second pixel group 24 are diagonally positioned.

[0054] The first pixel group 23 includes three red pixel units and one white pixel unit. Figure 4 In the diagram, R represents red light received by a red pixel unit, and W represents white light received by a white pixel unit. The second pixel group 24 includes three green pixel units and one white pixel unit. Figure 4 In the image, Gr represents the green light received by the green pixel unit in the second pixel group. The third pixel group 25 includes three green pixel units and one white pixel unit. Figure 4 In the image, Gb represents the green light received by the green pixel unit in the third pixel group. The fourth pixel group 26 includes three blue pixel units and one white pixel unit. Figure 4 In the diagram, B represents the blue light received by the blue pixel unit. It should be understood that Gr and Gb in the above diagram represent green light respectively. In order to distinguish the green light received by the different green pixel units in the second pixel group 24 and the third pixel group 25, Gr and Gb are used to represent them respectively.

[0055] As mentioned above, see Figure 3The pixel array 20 includes a color filter layer 21 and an image acquisition module 22. The pixel array 20 includes a first pixel unit, a second pixel unit, a third pixel unit, and a fourth pixel unit. See also... Figure 5 The first pixel unit includes a first filter area 211 and a first color information acquisition unit 221; the second pixel unit includes a second filter area 212 and a second color information acquisition unit 222; the third pixel unit includes a third filter area 213 and a third color information acquisition unit 223; and the fourth pixel unit includes a fourth filter area 214 and a brightness information acquisition unit 224. It is worth noting that the first filter area 211, the second filter area 212, the third filter area 213, and the fourth filter area 214 are all located in the color filter layer 21. The first color information acquisition unit 221, the second color information acquisition unit 222, the third color information acquisition unit 223, and the brightness information acquisition unit 224 are all located in the image acquisition module 22.

[0056] As an optional solution, the pixel array also includes a microlens group, and the first pixel unit may also include a first microlens 231, through which light can be focused onto the first filter area 211. Similarly, the second pixel unit may also include a second microlens 232, the third pixel unit may also include a third microlens 233, and the fourth pixel unit may also include a fourth microlens 234.

[0057] The first, second, third, and fourth pixel units filter different light rays by using filter areas located within their respective pixel units. For example, when the white light contains red, green, and blue light, the first filter area 211 of the first pixel unit allows only red light to pass through, blocking other colors; the second filter area 212 of the second pixel unit allows only green light to pass through, blocking other colors; the third filter area 213 of the third pixel unit allows only blue light to pass through, blocking other colors; and the fourth filter area 214 of the fourth pixel unit allows only white light (red, green, and blue) to pass through. The filter areas of the first to third pixel units obtain the color light (red, green, and blue light) related to the color information of the target object image, and the filter area of ​​the fourth pixel unit obtains the white light related to the brightness information of the target object image. The first pixel unit, the second pixel unit, the third pixel unit, and the fourth pixel unit mentioned above have the same size, which means that the opening size of the filter area in each pixel unit is the same. In the embodiments of this application, the filter area of ​​each pixel unit adopts a rectangular filter area.

[0058] The light rays, after passing through the corresponding filter area, illuminate the image acquisition module 22 for further processing (see [reference]). Figure 3The image acquisition module 22 can acquire the optical signals of the target object's color and brightness, convert them into voltage signals, and then convert the optical signals into digital signals. Combined with... Figure 5 In the structure shown, the first color information acquisition unit 221 of the first pixel unit receives red light, the second color information acquisition unit 222 of the second pixel unit receives green light, and the third color information acquisition unit 223 of the third pixel unit receives blue light. The brightness information acquisition unit 224 of the fourth pixel unit receives white light.

[0059] Please refer to the above. Figure 6 , Figure 6 The circuit diagram of the color information acquisition unit provided in the embodiment of this application is shown. The first color information acquisition unit, the second color information acquisition unit, and the third color information acquisition unit are all conventional four-transistor pixel sensors. Each color information acquisition unit includes a transmission transistor M. TG And floating diffusion region FD, transfer transistor M TG The control terminal receives control signals and transmits them via transistor M. TG The input terminal is connected to a photodiode PD, and the transmission transistor M TG The output terminal of the transmission transistor M TG When the control terminal receives a control signal, it outputs a voltage signal, which is transmitted by transistor M. TG The voltage signal from the photodiode (PD) is transferred to the floating diffusion region (FD) for storage. The photogenerated carriers accumulated in the photodiode (PD) are transferred to the floating diffusion region (FD) and converted into a voltage signal. This signal is then converted into a digital signal by an analog-to-digital converter (ADC) and enters the color information processing unit. In the case of multiple first pixel units, second pixel units, and third pixel units, each pixel unit contains a photodiode (PD) to receive the light signal. Figure 6 The other circuit devices shown are conventional electronic components in a four-tube pixel sensor, and will not be described in detail here.

[0060] refer to Figure 7 , Figure 7The circuit diagram of the brightness information acquisition unit provided in this application embodiment is shown. The brightness information acquisition unit has the same structure as each color information acquisition unit, the only difference being the received light. Therefore, the acquisition principle of the brightness information acquisition unit is the same as that of the color information unit, and will not be described again here. A fourth pixel unit (white pixel unit) is introduced into the pixel array. Since the white pixel unit allows red, green, and blue light of three different wavelengths to pass through, the brightness of the white pixel unit is higher than that of other pixel units that receive monochromatic light (such as the first pixel unit that receives red light, the second pixel unit that receives green light, etc.). Therefore, the image brightness output by the image sensor is higher than that output by the image sensor in the prior art that only uses monochromatic light to obtain brightness information.

[0061] See Figure 3 The image processing module 30 includes a color image processing unit, a brightness information processing unit, and a color fusion image unit. The color image processing unit processes the color information acquired by the image acquisition module 22, and the brightness information processing unit processes the brightness information acquired by the image acquisition module 22. The color fusion image unit fuses the processed color and brightness information to obtain a color image.

[0062] When processing the light received by the pixel array, the image processing module 30 employs two methods: one is to form a high-quality image at 1 / 4 resolution, and the other is to form a high-quality image at full resolution. The two methods will be explained in detail below.

[0063] To facilitate understanding of the image sensor's image formation principle provided in this application's embodiments, interpolation operations are first explained. Interpolation refers to using known data to predict unknown data. Image interpolation, given a pixel unit, predicts the value of that pixel unit based on information from its surrounding pixel units. Common interpolation algorithms can be divided into two categories: adaptive and non-adaptive. Adaptive methods can change according to the content of the interpolation (sharp edges or smooth textures), while non-adaptive methods perform the same processing on all pixel units. Non-adaptive algorithms include: nearest neighbor interpolation, bilinear interpolation, bicubic interpolation, spline interpolation, etc.

[0064] like Figure 8The flowchart shown illustrates how, for ease of description, the output signals (digital signals) after photoelectric conversion of the light received by each pixel unit are named. The output signals converted from red light received by the three first pixel units in the first pixel group are denoted as R1, R2, and R3, respectively; the output signal converted from white light received by the fourth pixel unit is denoted as W1. Similarly, the output signals converted from green light received by the three second pixel units in the second pixel group are denoted as Gr1, Gr2, and Gr3, respectively; the output signal converted from white light received by the fourth pixel unit is denoted as W2. The output signals converted from green light received by the three second pixel units in the third pixel group are denoted as Gb1, Gb2, and Gb3, respectively; the output signal converted from white light received by the fourth pixel unit is denoted as W3. Finally, the output signals converted from blue light received by the three first pixel units in the fourth pixel group are denoted as B1, B2, and B3, respectively; the output signal converted from white light received by the fourth pixel unit is denoted as W1. Among them, the output signals R1, R2, R3, Gr1, Gr2, Gr3, Gb1, Gb2, Gb3, B1, B2, and B3 are the color information of the target object. The output signals W1, W2, W3, and W4 are the brightness information of the target object.

[0065] When creating a high-quality image at 1 / 4 resolution, combine Figure 3 The pixel array 20 converts the received light into light signals, which are then processed in the image processing module 30. The image processing module 30 acquires the first color light received by the monochrome pixel units (first pixel unit, second pixel unit, and third pixel unit) in each pixel group, and performs interpolation calculations based on the first color light received by the monochrome pixel units in each pixel group. Through interpolation, it obtains the second color light corresponding to the pixel unit at the location of the white pixel unit (fourth pixel unit) in the pixel group. Based on the acquired first and second color light, it performs pixel binning on the four pixel units in each pixel group to obtain a pixel binning image. It also acquires brightness information based on the white light received by the white pixel units in each pixel group. Finally, it combines the pixel binning image formed by each pixel group with the corresponding brightness information of that pixel group to obtain a 1 / 4 resolution image.

[0066] Specifically, the color image processing unit obtains the original image of the pixel array through the color information acquisition unit and the brightness information acquisition unit. It then performs interpolation on the pixel position corresponding to the fourth pixel unit in the original image to obtain the color information of the pixel position where the fourth pixel unit is located. Taking the fourth pixel unit in the first pixel group as an example, interpolation based on the known R2 and R3 yields the color information R4 of the pixel position where the fourth pixel unit is located, where R4 = (R2 + R3) / 2. R1, R2, R3, and R4 are then combined into a single four-pixel image, resulting in the combined output signal R, R = (R1 + R2 + R3 + R4) / 4. Similarly, the same operation is performed on the second, third, and fourth pixel groups to obtain Gr = (Gr1 + Gr2 + Gr3 + Gr4) / 4; Gb = (Gb1 + Gb2 + Gb3 + Gb4) / 4; B = (B1 + B2 + B3 + B4) / 4. This results in a combined four-pixel image.

[0067] The R, Gr, Gb, and B values ​​in the obtained four-pixel-in-one image are combined with the four fourth pixel units W1, W2, W3, and W4 respectively to obtain a high-quality image with 1 / 4 resolution.

[0068] like Figure 9 As shown in the flowchart, when forming a high-quality image at full resolution, the image processing module is also used to perform remosaic demosaic processing on the output signal of the pixel array (the output signal of each pixel unit) to obtain the image; to perform interpolation operation on the white light received by each white pixel unit to obtain the brightness information corresponding to each pixel unit (including each white pixel unit and each monochrome pixel unit); and to combine the image obtained by demosaic with the brightness information corresponding to each pixel unit to obtain the full-resolution image.

[0069] Specifically, the color image processing unit obtains the original image through the color information acquisition unit and the brightness information acquisition unit. It then performs interpolation on the fourth pixel unit position in the original image to obtain the monochromatic information of the pixel position where the fourth pixel unit is located. Taking the fourth pixel unit in the first pixel group as an example, interpolation is performed based on the known R1, R2, and R3 to obtain the monochromatic information R4 of the pixel position where the fourth pixel unit is located, where R4 = (R2 + R3) / 2. Similarly, Gr = (Gr2 + Gr3) / 2; Gb = (Gb2 + Gb3) / 2; B = (B2 + B3) / 2. Based on the monochromatic information of each pixel unit in the pixel array obtained above, the color image processing unit performs remosaic de-mosaic processing and demosaic de-mosaic processing on the original image.

[0070] The brightness information processing unit performs interpolation calculations based on the acquired output signals W1, W2, W3, and W4. In the M-row and N-column pixel array, after acquiring the output signals W1, W2, W3, and W4, the position of the fourth pixel unit and the output signals are used in the interpolation calculation to obtain the brightness information corresponding to each pixel unit in the M-row and N-column pixel array.

[0071] The image after mosaic processing is fused with brightness information to obtain a high-quality image at full resolution.

[0072] As can be seen from the above description, in the pixel array provided in this application embodiment, a fourth pixel unit (white pixel unit) is introduced to receive white light. Since the white pixel unit allows red, green and blue light of three different wavelengths to pass through, the brightness of the white pixel unit is higher than that of other pixel units that receive monochromatic light (such as the first pixel unit that receives red light, the second pixel unit that receives green light, etc.). Therefore, the brightness of the image output by the image sensor is higher than that of the image output by the image sensor in the prior art that only uses monochromatic light to obtain brightness information, thereby improving the image resolution (the ability of the image sensor to capture image details) and signal-to-noise ratio (referring to the ratio of signal to noise in the image sensor).

[0073] The comparison of the high-quality image output at 1 / 4 resolution with the resolution of existing image sensors is as follows: Figure 10 and Figure 11 As shown. Figure 10 There is no texture information inside the circle, while Figure 11 The circles in the image contain obvious texture information, thus the image sensor provided in this embodiment of the invention can achieve a significant improvement in resolution.

[0074] The comparison of the high-quality, full-resolution image output with the resolution of existing image sensors is as follows: Figure 12 and Figure 13 As shown. Figure 12 There is no texture information inside the circle, while Figure 13 The circles within the image contain clear texture information, thus significantly improving the resolution of the image sensor provided in this embodiment. Furthermore, the signal-to-noise ratio (SNR) of the image sensor provided in this embodiment is 3 dB higher than that of prior art image sensors.

[0075] As can be seen from the above description, the image sensor provided in this application embodiment, compared with the image sensor in the prior art, improves the amount of light intake after introducing the fourth pixel unit, thereby improving the resolution and signal-to-noise ratio of the image sensor in the full-resolution high-quality image output format, and at the same time improving the resolution in the 1 / 4 resolution high-quality image output format.

[0076] refer to Figure 14 , Figure 14 Based on Figure 4 Another variation of the pixel array is shown. In Figure 14 In the image sensor shown, the number of fourth pixel units introduced in each pixel group has been increased. Each pixel group—first pixel group 23, second pixel group 24, third pixel group 25, and fourth pixel group 26—contains two fourth pixel units. Alternatively, the two fourth pixel units are arranged diagonally.

[0077] Introducing more fourth pixel units increases the amount of light entering the sensor, improving the resolution and signal-to-noise ratio of the image sensor in high-quality image output formats at full resolution. It can also simultaneously improve the resolution and signal-to-noise ratio in high-quality image output formats at 1 / 4 resolution.

[0078] It should be understood that Figure 14 This example only illustrates one specific arrangement of pixel arrays. In this embodiment, the arrangement order of pixel units in different pixel groups is not specifically limited. The fourth pixel units in different pixel groups may or may not be adjacent.

[0079] refer to Figure 15 , Figure 15 It shows the basis Figure 5 Another variation of the pixel array shown. Another pixel array arrangement provided in this application embodiment. In Figure 15 In the pixel array shown, the size of the fourth pixel unit is smaller than the sizes of the first pixel unit, the second pixel unit, and the third pixel unit.

[0080] refer to Figure 16 , Figure 16 A schematic diagram showing the arrangement of different types of pixel units is provided. Figure 16 The numbers in the text can be referenced. Figure 5 The same reference numerals are used in the diagram. The fourth pixel unit is surrounded by a metal shielding layer 215, which surrounds the fourth filter area 214 of the fourth pixel unit. The size of the white pixel unit after being surrounded by the metal shielding layer 215 is equal to the size of the monochrome pixel unit (first pixel unit, second pixel unit, or third pixel unit). Figure 16 In this design, the fourth filter area 214 of the fourth pixel unit is enclosed by a metal shielding layer 215. Specifically, the shielding layer can enclose only a portion of the fourth filter area 214, or it can completely enclose the fourth filter area 214. For example, the metal shielding layer 215 has a frame-shaped structure, and the fourth filter area 214 is located within this frame structure, thereby making the opening area of ​​the fourth filter area 214 smaller than the opening areas of the first filter area 211, the second filter area 212, and the third filter area 213.

[0081] In one alternative approach, the fourth pixel unit is 0.8 to 0.9 times the opening area of ​​the first pixel unit. For example, the opening area of ​​the fourth pixel unit is 0.8, 0.85, or 0.9 times the opening area of ​​the first pixel unit.

[0082] To better understand the impact of reducing the size of the fourth pixel unit on other types of pixel units, the following will combine... Figure 17 and Figure 18 Please provide an explanation. Figure 17 The diagram shows the light received by different pixel units when the first, second, third, and fourth pixel units are the same size. Figure 18 The diagram illustrates how different pixel units receive light when the size of the fourth pixel unit is smaller than the sizes of the first, second, and third pixel units. Here, W represents the white light received by the fourth pixel unit, R represents the red light received by the first pixel unit, G represents the green light received by the second pixel unit, and B represents the blue light received by the fourth pixel unit.

[0083] contrast Figure 17 Reference line a and Figure 18 Reference line b, reference line a, and reference line b represent the same exposure time. Since the first, second, and third pixel units receive monochromatic light, while the fourth pixel unit receives white light (while simultaneously receiving red, blue, and green light), the fourth pixel unit can receive more light within the same time period. The other pixel units receive monochromatic light less efficiently than the fourth pixel unit receives white light. (Comparison) Figure 17 and Figure 18 It can be seen that when the sizes of the first to fourth pixel units are equal, when the fourth pixel unit receives nearly saturated white light, the other pixel units receive relatively little light. And... Figure 18 As shown, reducing the size of the fourth pixel unit reduces its efficiency in receiving white light. Therefore, other pixel units can acquire more monochromatic light, allowing them to receive even more monochromatic light when the fourth pixel unit's white light reception becomes saturated. This results in a richer array of light representing the target object's color in the pixel array's output signal.

[0084] The fourth pixel unit provided in this application embodiment can improve resolution even after its size is reduced. (See reference...) Figure 19The schematic diagram shown will first explain the term "line pair," which will appear later in the text. A line pair is a specialized term in film and lens photography. Line pairs per millimeter generally refers to a unit of resolution, indicating how many pairs of lines an instrument can distinguish within one millimeter. The more line pairs that can be distinguished, the smaller the width of each line that can be resolved, and the better the resolution. Line pairs are a factor reflecting image resolution; the higher the image resolution, the more line pairs are required. Figure 19 In the image, pixel 1, pixel 2, pixel 3, pixel 4, and pixel 5 represent pixel units of different sizes.

[0085] by Figure 19 The line pairs shown are used as the standard for sampling tests. Figure 19 In the center line pair diagram, a black line and a white line form a line pair, and the black and white lines alternate to form 5 line pairs. If the width of pixel 1 is equal to the width of a line pair (the width of pixel 1 equals the width of one black line and one white line), then pixel 1 cannot display the line pair, so the sampling result resolution is 0. The resolution is determined by the MTF (Modulation Transfer Function). If the width of pixel 2 is half the width of a line pair (the width of one black line), then when pixel 2 corresponds one-to-one with the position of the line pair, the resolution of pixel 2 can reach 100. Pixel 3 has the same size as pixel 2, but its position is offset from the line pair by half a pixel width. Therefore, the sampling resolution of pixel 3 is 0. For pixels 4 and 5, the size is 1 / 4 of the line pair width. Regardless of their sampling position or spacing, pixels 4 and 5 achieve a sampling resolution of 100. Even after offsetting pixels 4 and 5 by half a pixel to obtain pixels 4' and 5', the sampling resolution remains 100. Comparing pixels 1, 2, 3, 4, and 5 shows that the smaller the pixel size (width), the better the line pair is represented, resulting in a higher image resolution. Therefore, reducing the size of the fourth pixel unit can improve the image resolution.

[0086] As can be seen from the above description, in the pixel array provided in this application embodiment, since the light efficiency received by the first pixel unit, the second pixel unit, and the third pixel unit is much smaller than that received by the fourth pixel unit, under the same exposure time, the output signal of the fourth pixel unit is always higher than that of the first pixel unit, the second pixel unit, and the third pixel unit. At this time, the brightness of the image will be relatively large, and the color will be pale. Therefore, when the size of the fourth pixel unit is smaller than that of other types of pixel units, the exposure of the fourth pixel unit can be reduced, the saturation time of the fourth pixel unit can be delayed, and the first pixel unit, the second pixel unit, and the third pixel unit can be more fully exposed, thereby increasing the image color signal. At the same time, reducing the size of the fourth pixel unit can also improve the image resolution.

[0087] refer to Figure 20 , Figure 20 This application illustrates another pixel array provided in an embodiment of the present application, in Figure 20 In the pixel array shown, based on the idea of ​​improving image resolution by reducing the size of the fourth pixel unit, the sizes of the first, second, third, and fourth pixel units were reset. The first pixel group includes two red pixel units and two white pixel units. Figure 20 In the diagram, R represents the red light received by the red pixel unit, and W represents the white light received by the white pixel unit. The second pixel group includes two green pixel units and two white pixel units. Figure 4 In the image, Gr represents the green light received by the green pixel unit in the second pixel group. The third pixel group consists of two green pixel units and two white pixel units. Figure 20 In the image, Gb represents the green light received by the green pixel unit in the third pixel group. The fourth pixel group includes two blue pixel units and two white pixel units. Figure 20 In the diagram, B represents the blue light received by the blue pixel unit. It should be understood that Gr and Gb in the above diagram represent green light respectively. In order to distinguish the green light received by the different green pixel units in the second and third pixel groups, Gr and Gb are used to represent them respectively.

[0088] The first, second, and third pixel units are all the same size, while the fourth pixel unit is smaller than the first pixel unit. In comparison... Figure 4 The fourth pixel unit shown, Figure 20 The fourth pixel unit shown is 0.8 to 0.9 times larger. Figure 4 The fourth pixel unit shown is, for example, 0.8x, 0.85x, or 0.9x. The sizes of the first, second, and third pixel units can be increased to... Figure 4 The same pixel unit shown is 1 to 4 times larger. For example, different sizes such as 1x, 2x, 3x, 4x, etc.

[0089] Continue to refer to Figure 20 Along the row and column directions of the pixel array, two monochrome pixel units are separated by a white pixel unit. This is to prevent the enlarged monochrome pixel units from interfering with each other's light intake. (See also...) Figure 21 , Figure 21 This diagram illustrates the light intake of different pixel units. Figure 21 As can be seen, when the first pixel unit, the second pixel unit, and the fourth pixel unit contain microlenses, the size of the first microlens 231 is larger than the size of the fourth microlens 234, thereby allowing more light to converge on the first filter area 211 and reducing the light reaching the fourth filter area 214. Simultaneously, the size of the second microlens 232 is also larger than the size of the fourth microlens 234, thereby allowing more light to converge on the second filter area 212 and reducing the light reaching the fourth filter area 214. The third pixel unit can adopt the same configuration as the first and second pixel units, which will not be described further here.

[0090] As described above, by changing the size of the microlens, the efficiency of light reception in the first, second, and third pixel units can be increased, while the efficiency of light reception in the fourth pixel unit can be decreased. This allows for more complete exposure of the first, second, and third pixel units, increasing the image color signal. Simultaneously, reducing the size of the fourth pixel unit can also improve image resolution. The principle is similar to... Figure 15 The principle behind the pixel array shown is the same, so it will not be repeated here.

[0091] refer to Figure 22 , Figure 22 It shows the basis Figure 3 The image sensor shown is a variation of the one shown. Figure 22 The image sensor shown incorporates a filter module 40. After being focused by the lens 10, the mixed incident light passes through the filter module 40 and illuminates the pixel array 20. The filter module 40 is positioned on the incident light side of the pixel array 20 to filter out stray light from the mixed incident light of complex wavelengths, leaving only the light that can pass through the pixel array 20 (i.e., the light emitted from the target object for imaging), thereby improving the imaging effect. For example, if the pixel array 20 requires light in both the white light band and the infrared light band, the filter module 40 can be a dual-passband filter module. The two passbands that the dual-passband filter module can pass through are the white light band and the infrared light band, respectively. If the infrared light band corresponding to the pixel array 20 is a specific narrowband infrared light band, then the dual-passband filter module can pass through that specific narrowband infrared light band. By employing a dual-band filter module that allows white light and infrared light to pass through while blocking stray light from other frequency bands, the impact of stray light on image sensor imaging can be reduced, thereby minimizing light interference and noise in subsequent modules and improving the image quality of the image sensor.

[0092] refer to Figure 23 In the pixel array, monochrome pixel units (first pixel unit, second pixel unit, and third pixel unit) are coated with a filter layer that blocks infrared light, while white pixel units (fourth pixel unit) receive both white light and infrared light. Figure 23 The filter layer is represented by a shadow in the image. The first, second, and third pixel units are all coated with a filter layer made of an infrared light-blocking material. This ensures that the first, second, and third pixel units only sense the red, green, and blue components of white light, guaranteeing color accuracy. The fourth pixel unit senses both white light and infrared light, enabling the use of infrared light as a brightness channel in extremely low light conditions, significantly improving the image sensor's light sensitivity and enhancing the image signal-to-noise ratio.

[0093] This application also provides an imaging device, which is an electronic device, such as a mobile phone, tablet computer, wearable electronic device, or other common devices with photographic functions. Of course, it can also be other types of electronic devices with photographic functions. The imaging device includes a housing and an image sensor of any of the above-mentioned types disposed within the housing. In the above technical solution, by introducing white pixel units in each pixel group, the sensitivity of the image sensor is improved, thereby enhancing the image resolution and signal-to-noise ratio.

[0094] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An image sensor, characterized by, The display panel comprises a plurality of pixel units; the plurality of pixel units comprise a first pixel group, a second pixel group, a third pixel group and a fourth pixel group arranged in an array, and the second pixel group and the third pixel group are diagonally arranged; wherein, the first pixel group comprises a first pixel unit and a fourth pixel unit; the second pixel group comprises a second pixel unit and a fourth pixel unit; the third pixel group comprises a second pixel unit and a fourth pixel unit; and the fourth pixel group comprises a third pixel unit and a fourth pixel unit; wherein, the first pixel unit, the second pixel unit and the third pixel unit are single-color pixel units for receiving light rays of different colors respectively; and the fourth pixel unit is a white pixel unit for receiving white light rays; the display panel further comprises an image processing module, which performs interpolation operation on first color light rays received by single-color pixel units in each pixel group to obtain second color light rays corresponding to pixel units at positions of white pixel units in the pixel group; performs four-pixel combination on the four pixel units in each pixel group according to the first color light rays and the second color light rays to obtain a four-pixel combination image; obtains luminance information from white light rays received by the white pixel units in each pixel group; and combines the four-pixel combination image formed by each pixel group with corresponding luminance information of the pixel group to obtain a 1 / 4 resolution image.

2. The image sensor of claim 1, wherein, In the first pixel group, the second pixel group, the third pixel group and the fourth pixel group, each pixel group comprises four pixel units arranged in an array; wherein, in the four pixel units of each pixel group, at least one pixel unit is the white pixel unit, and the remaining pixel units are single-color pixel units for receiving light rays of the same color.

3. The image sensor of claim 2, wherein, In each pixel group, there are three single-color pixel units for receiving light rays of the same color and one white pixel unit.

4. The image sensor of claim 3, wherein, In each adjacent two pixel groups, the white pixel unit in one pixel group and the white pixel unit in the other pixel group are separated by other pixel units.

5. The image sensor of claim 2, wherein, In each pixel group, there are two single-color pixel units for receiving light rays of the same color and two white pixel units; wherein, the two white pixel units are diagonally arranged.

6. The image sensor according to any one of claims 1 to 5, wherein The size of the white pixel unit is smaller than the size of the single-color pixel unit.

7. The image sensor of claim 6, wherein, The white pixel unit is wrapped with a metal shielding layer; after the white pixel unit is wrapped with the metal shielding layer, the size of the white pixel unit is equal to the size of the single-color pixel unit.

8. The image sensor according to any one of claims 1 to 7, wherein The display panel further comprises a lens for condensing light, which is located on the light-incident side of the plurality of pixel units.

9. The image sensor according to any one of claims 1 to 8, wherein The display panel further comprises a light filtering module arranged on the light-incident side of the plurality of pixel units.

10. The image sensor of claim 9, wherein, The light filtering module is a double-passband light filtering module, which can transmit white light rays and infrared light.

11. The image sensor of claim 9 or 10, wherein, The single-color pixel units are coated with a filter layer for blocking infrared light; and the white pixel units receive the white light rays and the infrared light.

12. The image sensor according to any one of claims 1 to 11, wherein The image processing module is further configured to perform demosaicing on the pixel array to obtain an image; interpolation operation is performed on the white light rays received by each white pixel unit to obtain luminance information corresponding to each pixel unit; The image obtained by demosaicing is combined with the luminance information corresponding to each pixel unit to obtain a full resolution image.

13. An image forming apparatus characterized by comprising: The image sensor as claimed in any one of claims 1 to 12 is provided in a housing.

Images