Ultrasonic image sensor and electronic device
By adjusting the layout of pixels and pixel circuits, the problem of excessively long image acquisition time in existing ultrasonic image sensors has been solved, resulting in faster image generation and better image quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN GOODIX TECH CO LTD
- Filing Date
- 2025-05-30
- Publication Date
- 2026-04-28
AI Technical Summary
In existing ultrasonic image sensors, the area requirements of the pixel circuit result in excessively long image acquisition time, making it impossible to effectively shorten the image generation time.
By optimizing the layout of pixels and pixel circuits, the distance between the center points of two adjacent pixels is between 65μm and 88μm, and the length and width of the pixel circuit are less than or equal to the length and width of the pixel group, so that an ultrasonic image can be obtained by generating pixel voltage in at least 2 times.
It shortens the ultrasonic image generation time, improves image generation efficiency, and maintains good image quality and signal-to-noise ratio.
Smart Images
Figure CN224176983U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of ultrasonic imaging technology, specifically to an ultrasonic image sensor and electronic device. Background Technology
[0002] Ultrasonic fingerprint recognition is a fingerprint recognition technology that has emerged in recent years. It enables in-display fingerprint recognition, and the key to this technology lies in the ultrasonic image sensor. In related technologies, to improve the image quality of fingerprints from thin fingers, the pixel pitch is typically reduced, usually to around 50 micrometers (μm). This means that in pixel circuit reuse schemes, at least four pixels' worth of area are needed to accommodate a single pixel circuit below it. Because at least four pixels share one pixel circuit, at least four separate image acquisition steps are required, resulting in a longer image acquisition time. Utility Model Content
[0003] In view of the above problems, this application provides an ultrasonic image sensor and electronic device to solve the above technical problems.
[0004] In a first aspect, embodiments of this application provide an ultrasonic image sensor, comprising: a pixel array including a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; and a pixel circuit array including a plurality of pixel circuits, the pixel circuits being electrically connected to a pixel group and disposed below the pixel group, the pixel circuits being used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages, the pixel group including a plurality of adjacent pixels; wherein the distance between the center points of two adjacent pixels is between 65 μm and 88 μm; the length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group. Using this embodiment, the distance between the center points of two adjacent pixels is between 65 μm and 88 μm, and the length of the pixel circuit is less than or equal to the length of the pixel group, and the width of the pixel circuit is less than or equal to the width of the pixel group. At least two pixels are sufficient to provide the area required for the pixel circuit, meaning that at least two pixel voltage generation operations are required to generate an ultrasonic image, thus shortening the time required to generate an ultrasonic image.
[0005] Secondly, embodiments of this application provide an ultrasonic image sensor, comprising: a pixel array including a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; and a pixel circuit array including a plurality of pixel circuits, the pixel circuits being electrically connected to a pixel group and disposed below the pixel group, the pixel circuits being used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages; wherein, the pixel group includes two adjacent pixels; the length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group. Using this embodiment, two pixels are sufficient to provide the area required for the pixel circuit, and an ultrasonic image can be generated by performing two pixel voltage generation operations, thus shortening the ultrasonic image generation time.
[0006] Thirdly, embodiments of this application provide an ultrasonic image sensor, comprising: a pixel array including a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; and a pixel circuit array including a plurality of pixel circuits, the pixel circuits being electrically connected to a pixel group and disposed below the pixel group, the pixel circuits being used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages; wherein, the pixel group includes two adjacent pixels, the area of the pixel group is greater than or equal to the area of the pixel circuit, and the area of the pixel group is less than 1.5 times the area of the pixel circuit. Using this embodiment, two pixels can provide the area required for the pixel circuit, and an ultrasonic image can be generated by performing two pixel voltage generation operations, thus shortening the ultrasonic image generation time.
[0007] Fourthly, embodiments of this application provide an electronic device, including a device body and an ultrasonic image sensor of the above embodiments disposed on the device body. The ultrasonic image sensor further includes an upper electrode and a piezoelectric layer, with the piezoelectric layer located between the upper electrode and the pixel array.
[0008] These or other aspects of this application will become more apparent in the following description of the embodiments. Attached Figure Description
[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0010] Figure 1 A perspective view of an ultrasonic image sensor provided in an embodiment of this application is shown.
[0011] Figure 2 A top view of the pixel array provided in an embodiment of this application is shown.
[0012] Figure 3 A schematic diagram of a pixel and pixel circuit provided in an embodiment of this application is shown. Detailed Implementation
[0013] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0014] To enable those skilled in the art to better understand the solutions of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0015] In the embodiments of this application, it should be noted that, in this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0016] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0017] In the description of the embodiments of this application, the words "example" or "for example" are used to indicate exemplification, illustration, or description. Any embodiment or design described as "example" or "for example" in the embodiments of this application is not to be construed as being more preferred or having more advantages than another embodiment or design. The use of the words "example" or "for example" is intended to present relative concepts in a clear manner.
[0018] Furthermore, in the embodiments of this application, "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two". "At least one" can be understood as one or more, such as one, two, or more. For example, including at least one means including one, two, or more, and is not limited to which ones are included. For example, including at least one of A, B, and C, then it could include A, B, C, A and B, A and C, B and C, or A and B and C.
[0019] It should be noted that in the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after it are in an "or" relationship.
[0020] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.
[0021] In the circuit structure provided in the embodiments of this application, nodes such as the first node and the second node do not represent actual existing components, but rather represent the junction points of related couplings in the circuit diagram. In other words, these nodes are equivalent to the junction points of related couplings in the circuit diagram.
[0022] Figure 1 A perspective view of an ultrasonic image sensor provided in an embodiment of this application is shown, such as... Figure 1As shown, the ultrasonic image sensor 100 may include a pixel array 113 and a pixel circuit array 120. The pixel array 113 includes multiple pixels with identical structures and disposed on the same plane. Each pixel generates an electrical signal in response to ultrasonic waves reflected from an object to be imaged (e.g., a finger 200) and propagating through a piezoelectric layer. The pixel array 113 is also referred to as a lower electrode array, which includes multiple lower electrodes, each of which can be understood as a pixel. The pixel circuit array 120 includes multiple pixel circuits with identical structures and disposed on the same plane. The pixel circuits can be implemented using complementary metal-oxide-semiconductor (CMOS) technology. Each pixel circuit is electrically connected to a pixel group and disposed below the pixel group. The pixel circuits detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages. The pixel circuit array includes multiple adjacent pixel circuits. The pixel voltages can generate an ultrasonic image of the object to be imaged. It should be understood that the ultrasonic image sensor 100 may also include scanning circuits, controllers, readout circuits, etc., which will not be elaborated upon in this embodiment.
[0023] Specifically, refer to Figure 1 As shown, pixel array 113 includes multiple pixels, which form a two-dimensional array, as referenced. Figure 2 As shown, the pixel array 113 has a size of N×M. That is, the pixel array 113 has N rows of pixels (rows 0 to N-1) and M columns of pixels (columns 0 to M-1). In the specific implementation, refer to... Figure 1 and Figure 3 As shown, the ultrasonic image sensor 100 may include an upper electrode layer 111 and a piezoelectric layer 112. The piezoelectric layer 112 may include a polyvinylidene fluoride (PVDF) layer or other types of piezoelectric layers. (Reference) Figure 3 As shown, a cover plate 101 can also be disposed on the upper electrode layer 111. The cover plate 101 can serve as a protective coating for the components located below the cover plate 101, and the object to be imaged can be placed on the surface of the cover plate 101. In under-display ultrasonic fingerprint recognition applications, a display screen can also be disposed on the cover plate 101, that is, the ultrasonic image sensor 100 is located under the display screen, forming an under-display fingerprint recognition system, or, in some embodiments, the cover plate 101 is the display screen itself. In some embodiments, the upper electrode layer 111, the piezoelectric layer 112, and the pixels can also be used to generate and emit ultrasonic waves to the object to be imaged in response to a pulse excitation signal, see reference. Figure 3 As shown, the upper electrode layer 111 can also be connected to a sine wave pulse generator. During the transmission phase, the sine wave pulse generator generates a high-voltage sine wave V. TXA high-voltage sine wave is applied to the upper electrode layer 111, and the piezoelectric layer 112 is excited by the high-voltage sine wave, converting electrical energy into mechanical energy to generate ultrasonic waves. All pixels can simultaneously emit ultrasonic waves, which are transmitted through the cover plate 101 to the object to be imaged (e.g., finger 200). During the receiving phase, all pixels can generate electrical signals in response to the ultrasonic waves reflected from the object to be imaged and propagated through the cover plate 101, the upper electrode layer 111, and the piezoelectric layer 112. This embodiment eliminates the need for a separate ultrasonic transmitter, reducing the thickness of the ultrasonic image sensor 100. It should be understood that the embodiments of this application are not limited thereto; in specific implementations, a separate ultrasonic transmitter can be used to generate and emit ultrasonic waves to the object to be imaged.
[0024] Specifically, refer to Figure 1 As shown, the pixel circuit array 120 includes multiple pixel circuits forming a two-dimensional array. In this embodiment, to reduce the circuit area of the ultrasonic image sensor 100, adjacent pixels form a pixel group, and the pixel circuits in the pixel circuit array 120 are connected to and positioned below this pixel group. The pixel circuits are used to detect the electrical signals of the pixels in the pixel group connected to them to generate corresponding pixel voltages. In a specific implementation, the pixel circuits are used in a time-division multiplexing manner to detect the electrical signals of the pixels in the pixel group connected to them to generate corresponding pixel voltages. In a specific implementation, the pixel circuit 121 is also used to amplify the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages. (Reference) Figure 3 As shown, the pixel circuit 121 may include an amplifier Amp, an integrating capacitor unit Cint, a reset switch, and a pixel selection switch. The integrating capacitor unit Cint is connected to the input of the amplifier Amp. Figure 3 (Shown as negative input) between the input and output. The reset switch RST is connected in parallel with the integrating capacitor unit Cint. The pixel selection switch is connected between the pixel in the pixel group and the input of the amplifier Amp. Figure 3 The area between the negative input terminals (shown as the negative input) is used to selectively connect any pixel in the pixel group to the amplifier's input. (See reference) Figure 3 As shown, in the case where the pixel group includes two adjacent pixels, the pixel selection switch includes switch K21 and switch K22. Switch K21 is connected between pixel 113-1 and the negative input of amplifier Amp, and switch K22 is connected between pixel 113-2 and the negative input of amplifier Amp. When switch K21 is on and switch K22 is off, pixel 113-1 is connected to the negative input of amplifier Amp, and amplifier Amp amplifies the electrical signal of pixel 113-1 to generate a pixel voltage for pixel 113-1. When switch K22 is on and switch K21 is off, pixel 113-2 is connected to the negative input of amplifier Amp, and amplifier Amp amplifies the electrical signal of pixel 113-2 to generate a pixel voltage for pixel 113-2. (Reference) Figure 3As shown, the amplification gain of amplifier Amp is based on the ratio of the capacitance of the integrating capacitor unit Cint to the sensing capacitance Cp of the pixel, where the sensing capacitance Cp of the pixel is proportional to the area of the pixel.
[0025] Furthermore, considering that the circuit noise of a pixel circuit is related to its circuit area, generally, the smaller the circuit area of a pixel circuit, the greater its circuit noise. When the width of a pixel circuit is greater than or equal to 60μm and the length is greater than or equal to 120μm, the pixel circuit has a larger area, thus resulting in lower circuit noise. To connect the pixel circuit to a pixel group and place it below the pixel group, the number of pixels in the pixel group can be increased. That is, increasing the number of pixels in the pixel group increases the area occupied by the pixel group, thereby allowing the pixel circuit to be placed below the pixel group. Since the pixel circuit generates the pixel voltage of the pixels in a time-division multiplexing manner, the more pixels in the pixel group, the longer it takes to generate an ultrasonic image. For example, if the pixel group includes 4 pixels, the pixel circuit needs to perform 4 pixel voltage generation operations to generate an ultrasonic image. This can be understood as the pixel circuit sharing one pixel circuit, requiring the pixel circuit to work in a time-division multiplexing manner 4 times to obtain one image. Since each image acquisition requires 4 detection integrations before the integrated signal can be read out, the image acquisition time is relatively long. In some embodiments, the area occupied by a pixel is increased to provide the area required for a larger pixel circuit. The area of a pixel is positively correlated with the distance between the center points of two adjacent pixels, and increasing this distance increases the area occupied by the pixel. As one implementation, the distance between the center points of two adjacent pixels is between 65 μm and 88 μm. In this case, at least two pixels are sufficient to provide the area required for the pixel circuit, meaning that an ultrasonic image can be generated with at least two pixel voltage generation operations, thus shortening the ultrasonic image generation time. More specifically, the length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group, allowing the pixel circuit to be positioned below the pixel group. Furthermore, for the same recognition area, a smaller pixel area results in more pixels, which in turn increases the readout and data transmission time. When the pixel size is greater than or equal to 65 μm, the ultrasonic image generation time can be shortened while maintaining good image accuracy. More specifically, considering that the fingerprint ridge period of an average adult is at least 350um when performing fingerprint imaging, and that sampling 4 points every 350um period will not affect the imaging of the fingerprint ridge, the maximum distance between the center points of two adjacent pixels in this case is 350um / 4≈88um. Therefore, the distance between the center points of two adjacent pixels is set to be less than or equal to 88um.
[0026] In some specific implementations, to improve pixel voltage, the pixel circuit generates pixel voltage by electrically integrating and superimposing the reflected echo signals corresponding to multiple ultrasonic wave emissions. The amplification gain of the pixel circuit is positively correlated with the sensing capacitance of the pixel, which is proportional to the area occupied by the pixel. The pixel area is positively correlated with the distance between the center points of two adjacent pixels; that is, the greater the distance between the center points of two adjacent pixels, the larger the pixel area. Therefore, the larger the pixel area, the greater the amplification gain of the pixel circuit. The greater the amplification gain of the pixel circuit, the fewer integration steps are required. The pixel circuit needs a relatively large number of integration steps to ensure high performance; the more integration steps, the higher the signal-to-noise ratio, but the longer the image acquisition time. When the distance between the center points of two adjacent pixels is between 65μm and 88μm, a reasonable number of integration steps can be achieved, achieving a balance between image acquisition time and performance. As a typical implementation, the distance between the center points of two adjacent pixels is between 75μm and 88μm, and the width of the pixel circuit is greater than or equal to 60μm and the length is greater than or equal to 120μm. In this typical implementation, a minimum of two pixels can provide the area required for the pixel circuit, and the larger pixel area results in a larger amplification gain of the pixel circuit, which can achieve a better balance between signal-to-noise ratio and integration times, while also achieving a smaller acquisition time and better image quality.
[0027] In practice, to reduce map acquisition time, refer to Figure 1 , Figure 2 and Figure 3 As shown, a pixel group consists of two adjacent pixels. Figure 2 In a pixel group consisting of two pixels, the pixels are labeled as pixel P1 and pixel P2. The pixel circuits in the pixel circuit array 120 are connected to pixels P1 and P2 in the pixel group. Figure 3 The pixels in the pixel group are labeled as pixel 113-1 and pixel 113-2, respectively. Pixel circuit 121 in pixel circuit array 120 is connected to pixels 113-1 and 113-2 in the pixel group. In this way, an ultrasonic image can be generated by performing two pixel voltage generation operations, significantly reducing the image acquisition time compared to implementations with three, four, or more pixels in the pixel group. More specifically, the distance between the center points of two adjacent pixels is between 65μm and 88μm, and the area of the pixel group is less than 1.5 times the area of the pixel circuit. The larger pixel area results in a higher amplification gain for the pixel circuit, achieving a better balance between signal-to-noise ratio and integration count, while simultaneously achieving shorter acquisition time and better image quality.
[0028] refer to Figure 3As shown, the pixel circuit 121 performs N integrations to obtain the pixel voltage. Specifically, the three processes of sound wave emission, echo reception, and detection integration are called one integration. Each integration is as follows: starting from the starting point of the sine wave, after a preset flight time, the piezoelectric layer 112 receives the emitted ultrasonic wave and induces an electrical signal (i.e., echo voltage), and the pixel circuit 121 obtains the voltage increment. After N integrations, the pixel circuit 121 generates the pixel voltage Vout. The pixel voltage is Vout = N * Vecho * Cp / Cint, where Vecho is the echo signal amplitude, Cp is the sensing capacitance of the pixel, and Cint is the capacitance of the integration capacitor unit. When the distance between the center points of two adjacent pixels is between 75μm and 88μm, a better number of integrations and a shorter image acquisition time can be obtained. For example, when the distance between the center points of two adjacent pixels increases from 65um to 80um, Cp increases by 1.5 times. Therefore, the value of N can be reduced to 2N / 3, the image acquisition time is shortened, and the 2N / 3th integration can achieve a higher signal-to-noise ratio.
[0029] In some embodiments, the pixel group comprises two adjacent pixels, so the pixel circuit can generate an ultrasonic image by performing pixel voltage generation twice. The length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group, allowing the pixel circuit to be positioned below the pixel group. Using this embodiment, generating an ultrasonic image by performing pixel voltage generation twice can shorten the ultrasonic image generation time. More specifically, the width of the pixel circuit is greater than or equal to 60 μm, and the length is greater than or equal to 120 μm, resulting in lower circuit noise and reducing the impact of circuit noise on the pixel voltage, thus improving the pixel voltage generation accuracy. Furthermore, the area of the pixel group is less than 1.5 times the area of the pixel circuit, allowing the pixel to have a larger area. Since the amplification gain of the pixel circuit is positively correlated with the sensing capacitance of the pixel, and the sensing capacitance of the pixel is proportional to the pixel area, a larger pixel area results in a greater amplification gain. A larger amplification gain means fewer integration steps are needed to generate the pixel voltage, thus reducing the number of integration steps and the image acquisition time. More specifically, when the distance between the center points of two adjacent pixels is between 65μm and 88μm, a reasonable number of integration steps can be achieved, balancing image acquisition time and performance. Preferably, when the distance between the center points of two adjacent pixels is between 75μm and 88μm, a better number of integration steps and less image acquisition time can be obtained. As a typical implementation, a pixel group includes two adjacent pixels, the width of the pixel circuit is greater than or equal to 60μm, and the length is greater than or equal to 120μm. The area of the pixel group is less than 1.5 times the area of the pixel circuit. This implementation reduces image acquisition time and ensures image acquisition quality by reducing the time-division multiplexing steps of the pixel circuit, increasing the amplification gain of the pixel circuit by increasing the pixel area to reduce the number of integration steps to generate the pixel voltage, and reducing the circuit noise of the pixel circuit by using a larger pixel circuit area.
[0030] In some embodiments, the pixel group comprises two adjacent pixels, so the pixel circuit generates an ultrasonic image by performing pixel voltage generation twice. The area of the pixel group is greater than or equal to the area of the pixel circuit, allowing the pixel circuit to be positioned below the pixel group. The area of the pixel group is less than 1.5 times the area of the pixel circuit, reducing the number of integration steps and image acquisition time. More specifically, a reasonable number of integration steps can be achieved when the distance between the center points of two adjacent pixels is between 65 μm and 88 μm, achieving a balance between image acquisition time and performance. Preferably, a better number of integration steps and shorter image acquisition time can be obtained when the distance between the center points of two adjacent pixels is between 75 μm and 88 μm. More specifically, the width of the pixel circuit is greater than or equal to 60 μm and the length is greater than or equal to 120 μm, resulting in lower circuit noise, reducing the impact of circuit noise on the pixel voltage, and improving the accuracy of pixel voltage generation.
[0031] This application provides an electronic device, including a device body and an ultrasonic image sensor as described in the above embodiments disposed on the device body. Electronic devices include, but are not limited to, mobile communication devices, ultra-mobile personal computer devices, portable entertainment devices, and other electronic devices with data interaction functions. Mobile communication devices are characterized by having mobile communication functions and primarily aiming to provide voice and data communication. Such terminals include: smartphones (e.g., iPhones), multimedia phones, feature phones, and low-end phones. Ultra-mobile personal computer devices fall under the category of personal computers, possessing computing and processing functions, and generally also have mobile internet access capabilities. Such terminals include: PDAs, MIDs, and UMPC devices, such as iPads. Portable entertainment devices can display and play multimedia content. These devices include: audio and video players (e.g., iPods), handheld game consoles, e-book readers, as well as smart toys and portable car navigation devices.
[0032] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Although this application has disclosed preferred embodiments as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. An ultrasonic image sensor, characterized in that, include: A pixel array comprising a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; A pixel circuit array includes multiple pixel circuits, each pixel circuit being electrically connected to a pixel group and disposed below the pixel group. The pixel circuits are used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages. The pixel group includes multiple adjacent pixels. The distance between the center points of two adjacent pixels is between 65μm and 88μm; the length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group.
2. The ultrasonic image sensor as described in claim 1, characterized in that, The distance between the center points of two adjacent pixels is between 75 μm and 88 μm.
3. The ultrasonic image sensor as described in claim 1 or 2, characterized in that, The pixel group comprises two adjacent pixels, and the area of the pixel group is less than 1.5 times the area of the pixel circuit.
4. The ultrasonic image sensor as described in claim 1 or 2, characterized in that, The pixel circuit has a width greater than or equal to 60 μm and a length greater than or equal to 120 μm.
5. The ultrasonic image sensor as described in claim 1, characterized in that, The pixel circuit is further configured to amplify the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages, the pixel circuit comprising: Amplifier; An integrating capacitor unit is connected between the input and output of the amplifier; A reset switch is connected in parallel with the integrating capacitor unit; A pixel selection switch is connected between each pixel in the pixel group and the input of the amplifier, for selectively connecting any one pixel in the pixel group to the input of the amplifier; The amplification gain of the amplifier is based on the ratio of the capacitance of the integrating capacitor unit to the sensing capacitance of the pixel; the pixel voltage is generated based on the electrical integration and superposition of the reflected echo signals corresponding to multiple ultrasonic wave emissions; the amplification gain of the pixel circuit is positively correlated with the sensing capacitance of the pixel, and the sensing capacitance of the pixel is proportional to the area of the pixel.
6. An ultrasonic image sensor, characterized in that, include: A pixel array comprising a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; A pixel circuit array includes multiple pixel circuits, each pixel circuit being electrically connected to a pixel group and disposed below the pixel group. The pixel circuits are used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages. The pixel group comprises two adjacent pixels; the length of the pixel circuit is less than or equal to the length of the pixel group, and the width is less than or equal to the width of the pixel group.
7. The ultrasonic image sensor as described in claim 6, characterized in that, The area of the pixel group is less than 1.5 times the area of the pixel circuit.
8. The ultrasonic image sensor as described in claim 6 or 7, characterized in that, The distance between the center points of two adjacent pixels is between 75μm and 88μm; the width of the pixel circuit is greater than or equal to 60μm and the length is greater than or equal to 120μm.
9. The ultrasonic image sensor as described in claim 6 or 7, characterized in that, The pixel circuit is further configured to amplify the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages, the pixel circuit comprising: Amplifier; An integrating capacitor unit is connected between the input and output of the amplifier; A reset switch is connected in parallel with the integrating capacitor unit; A pixel selection switch is connected between each pixel in the pixel group and the input of the amplifier, for selectively connecting any one pixel in the pixel group to the input of the amplifier; The amplification gain of the amplifier is based on the ratio of the capacitance of the integrating capacitor unit to the sensing capacitance of the pixel; the pixel voltage is generated based on the electrical integration and superposition of the reflected echo signals corresponding to multiple ultrasonic wave emissions; the amplification gain of the pixel circuit is positively correlated with the sensing capacitance of the pixel, and the sensing capacitance of the pixel is proportional to the area of the pixel.
10. An ultrasonic image sensor, characterized in that, include: A pixel array comprising a plurality of pixels, the pixels being used to generate electrical signals in response to reflection from an object to be imaged and via a piezoelectric layer; A pixel circuit array includes multiple pixel circuits, each pixel circuit being electrically connected to a pixel group and disposed below the pixel group. The pixel circuits are used to detect the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages. The pixel group comprises two adjacent pixels, the area of the pixel group is greater than or equal to the area of the pixel circuit, and the area of the pixel group is less than 1.5 times the area of the pixel circuit.
11. The ultrasonic image sensor as described in claim 10, characterized in that, The distance between the center points of two adjacent pixels is between 65 μm and 88 μm.
12. The ultrasonic image sensor as described in claim 10 or 11, characterized in that, The distance between the center points of two adjacent pixels is between 75μm and 88μm; the width of the pixel circuit is greater than or equal to 60μm and the length is greater than or equal to 120μm.
13. The ultrasonic image sensor as described in claim 10 or 11, characterized in that, The pixel circuit is further configured to amplify the electrical signals of the pixels in the pixel group to generate corresponding pixel voltages, the pixel circuit comprising: Amplifier; An integrating capacitor unit is connected between the input and output of the amplifier; A reset switch is connected in parallel with the integrating capacitor unit; A pixel selection switch is connected between each pixel in the pixel group and the input of the amplifier, for selectively connecting any one pixel in the pixel group to the input of the amplifier; The amplification gain of the amplifier is based on the ratio of the capacitance of the integrating capacitor unit to the sensing capacitance of the pixel; the pixel voltage is generated based on the electrical integration and superposition of the reflected echo signals corresponding to multiple ultrasonic wave emissions; the amplification gain of the pixel circuit is positively correlated with the sensing capacitance of the pixel, and the sensing capacitance of the pixel is proportional to the area of the pixel.
14. An electronic device, characterized in that, The device includes a main body and an ultrasonic image sensor as described in any one of claims 1 to 13 disposed on the main body. The ultrasonic image sensor further includes an upper electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the upper electrode and the pixel array.