An ultrasonic sensor, a sensor module, and an electronic device

Abstract

The application provides an ultrasonic sensor, a sensor module and an electronic device. Based on the positional relationship between the non-collection area and the collection area, the piezoelectric auxiliary structure can be distributed on the side of the piezoelectric pixel array. In this way, the piezoelectric auxiliary structure can emit ultrasonic waves from the position beside the piezoelectric pixel array and close to the edge of the piezoelectric pixel array. In combination with the ultrasonic waves emitted by the piezoelectric pixels at the edge position of the piezoelectric pixel array, the sound emission intensity at the edge position of the piezoelectric pixel array can be enhanced, so that more ultrasonic waves at this position can form more echo signals after being reflected by the target object. This helps to improve the signal receiving intensity at the edge position of the piezoelectric pixel array, so that the edge position of the image is clearer, and a better basis is provided for accurate and reliable identification of the target object.

Description

Technical Field

[0001] This application relates to the field of biometric technology, and more specifically, to an ultrasonic sensor, a sensor module, and an electronic device. Background Technology

[0002] Ultrasonic fingerprint recognition technology has become an important direction in the field of biometrics for mobile devices due to its ability to penetrate the skin surface, its good adaptability to dry and wet fingers, and its high security. A typical ultrasonic fingerprint sensor consists of a two-dimensional array of a large number of piezoelectric pixels (e.g., based on PVDF or its composite materials). During operation, the ultrasonic fingerprint sensor emits ultrasonic waves through the piezoelectric effect. After the ultrasonic waves are reflected by the ridges and valleys of the fingerprint, they are received by the ultrasonic fingerprint sensor and converted into target recognition signals, thereby reconstructing the fingerprint image.

[0003] Despite the advantages mentioned above, existing ultrasonic fingerprint sensors still have a significant technical drawback in practical applications: the signal intensity collected by the piezoelectric pixels in the edge region of the two-dimensional array is weaker than that in the central region, which easily causes the edge parts of the reconstructed fingerprint image to be blurred, affecting the overall accuracy and reliability of fingerprint recognition. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the prior art by providing an ultrasonic sensor, a sensor module, and an electronic device.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In one aspect of this application, an ultrasonic sensor is provided, comprising: a substrate, the substrate including a acquisition area and a non-acquisition area located around the acquisition area; a piezoelectric pixel array disposed on the acquisition area of ​​the substrate; a piezoelectric auxiliary structure disposed on the non-acquisition area of ​​the substrate; when the piezoelectric pixel array is in a receiving state, it is configured to receive an echo signal and output a target object identification signal, wherein the echo signal includes an ultrasonic signal emitted by the piezoelectric pixel array and the piezoelectric auxiliary structure and returned by the target object.

[0006] Optionally, when the piezoelectric pixel array is in the receiving state, the piezoelectric auxiliary structure is in the non-receiving state and configured not to receive echo signals.

[0007] Optionally, the piezoelectric auxiliary structure is connected to a fixed reference potential via an auxiliary switch; the auxiliary switch is switched on to the fixed reference potential so that the piezoelectric auxiliary structure is in a non-receiving state.

[0008] Optionally, the reference potential can be fixed as the ground potential.

[0009] Optionally, the piezoelectric auxiliary structure includes a stacked lower electrode, an auxiliary piezoelectric layer, and an upper electrode; when one of the lower electrode and the upper electrode receives a driving signal, the piezoelectric auxiliary structure emits an ultrasonic signal; the other of the lower electrode and the upper electrode is connected to a fixed reference potential via an auxiliary switch.

[0010] Optionally, the piezoelectric auxiliary structure is arranged around the periphery of the piezoelectric pixel array.

[0011] Optionally, the piezoelectric auxiliary structure is divided into multiple piezoelectric auxiliary units along the periphery of the piezoelectric pixel array, with the upper unit electrodes of adjacent piezoelectric auxiliary units spaced apart and / or the lower unit electrodes spaced apart.

[0012] Optionally, the piezoelectric pixel array and the piezoelectric auxiliary structure are arranged continuously or at intervals.

[0013] Optionally, when the piezoelectric pixel array and the piezoelectric auxiliary structure are spaced apart, the pixel piezoelectric layer of the piezoelectric pixel array and the auxiliary piezoelectric layer of the piezoelectric auxiliary structure are spaced apart, and an acoustic impedance matching layer is filled at the space between the pixel piezoelectric layer of the piezoelectric pixel array and the auxiliary piezoelectric layer of the piezoelectric auxiliary structure.

[0014] Optionally, the ultrasonic sensor further includes a circuit structure, which includes: a driving circuit electrically connected to the piezoelectric pixel array and the piezoelectric auxiliary structure respectively; and a receiving circuit electrically connected to the piezoelectric pixel array and disconnected from the piezoelectric auxiliary structure, configured to receive a target identification signal.

[0015] Optionally, when the piezoelectric auxiliary structure is divided into multiple piezoelectric auxiliary units along the periphery of the piezoelectric pixel array, the driving circuit outputs at least two different driving signals to the multiple piezoelectric auxiliary units.

[0016] Optionally, the driving circuit includes a first circuit and a second circuit, wherein the first circuit is connected to the piezoelectric pixel array for driving, and the second circuit is connected to the piezoelectric auxiliary structure for driving.

[0017] Optionally, the first circuit outputs a first driving signal to the piezoelectric pixel array, and the second circuit outputs a second driving signal to the piezoelectric auxiliary structure, wherein the first driving signal and the second driving signal have different signal amplitudes, pulse widths, and / or delays.

[0018] Optionally, the circuit structure is located on the substrate, and in the thickness direction of the substrate, the orthographic projection of the piezoelectric auxiliary structure and the orthographic projection of the circuit structure at least partially overlap.

[0019] In another aspect of this application, a sensor module is provided, including a control chip and any of the above-described ultrasonic sensors. The control chip is disposed on the substrate of the ultrasonic sensor and is electrically connected to the piezoelectric pixel array and / or piezoelectric auxiliary structure in the ultrasonic sensor.

[0020] In another aspect of this application, an electronic device is provided, comprising: a device body and a data acquisition device, wherein the data acquisition device is disposed on the device body and configured to transmit ultrasonic signals toward an ultrasonic recognition area of ​​the device body and receive echo signals returned by a target object within the ultrasonic recognition area; the data acquisition device is any of the above-mentioned ultrasonic sensors or sensor modules.

[0021] Optionally, the main body of the device includes a display screen with an ultrasonic recognition area, and the acquisition device is located below the display screen.

[0022] The beneficial effects of this application include: This application provides an ultrasonic sensor, sensor module, and electronic device. By adding a piezoelectric auxiliary structure, the acoustic intensity of the ultrasonic sensor is enhanced, allowing more ultrasonic waves to be emitted towards the target object. Simultaneously, based on the positional relationship between the non-collection area and the collection area, the piezoelectric auxiliary structure can be distributed beside the piezoelectric pixel array. This allows the piezoelectric auxiliary structure to emit ultrasonic waves from beside and near the edges of the piezoelectric pixel array. Combined with the ultrasonic waves emitted from the edge positions of the piezoelectric pixel array, the acoustic intensity at the edge positions is enhanced. This results in more ultrasonic waves being reflected by the target object, forming more echo signals, which helps improve the signal reception strength at the edge positions of the piezoelectric pixel array, making the image edge positions clearer and providing a better foundation for accurate and reliable target object identification. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is one of the structural schematic diagrams of an ultrasonic sensor provided in the embodiments of this application; Figure 2 A top view of an ultrasonic sensor provided in an embodiment of this application; Figure 3 A top view of another ultrasonic sensor provided in an embodiment of this application; Figure 4 This is one of the schematic diagrams of a circuit structure provided in an embodiment of this application; Figure 5 This is a second schematic diagram of a circuit structure provided in an embodiment of this application; Figure 6 This is a second schematic diagram of the structure of an ultrasonic sensor provided in an embodiment of this application; Figure 7 This is the third schematic diagram of the structure of an ultrasonic sensor provided in the embodiments of this application; Figure 8 This is a schematic diagram of the structure of a sensor module provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0025] Icons: 11-Ultrasound; 12-Echo signal; 100-Ultrasound sensor; 110-Substrate; 111-Acquisition area; 112-Non-acquisition area; 120-Piezoelectric pixel array; 121-Top electrode; 122-Pixel piezoelectric layer; 123-Bottom electrode; 1231-First sub-electrode; 130-Piezoelectric auxiliary structure; 131-Top electrode; 132-Auxiliary piezoelectric layer; 133-Bottom electrode; 134-Piezoelectric auxiliary unit; 141- Protective layer; 142 - Acoustic impedance matching layer; 150 - Circuit structure; 151 - First circuit; 152 - First switch; 153 - Second switch; 154 - Third switch; 155 - Signal amplifier; 156 - Second circuit; 1561 - Fourth switch; 1562 - Fifth switch; 157 - Auxiliary switch; 200 - Sensor module; 300 - Electronic device; 310 - Display screen; 320 - Acoustic transition layer; 400 - Finger. Detailed Implementation

[0026] 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 some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The target objects in this application include, but are not limited to, fingers, palms, and faces. Correspondingly, the biometric information, depending on the target object, can be fingerprint information, palm print information, facial information, etc.

[0028] In one aspect of this application, an ultrasonic sensor is provided, comprising: a substrate, the substrate including a acquisition area and a non-acquisition area located around the acquisition area; a piezoelectric pixel array disposed in the acquisition area of ​​the substrate; a piezoelectric auxiliary structure disposed in the non-acquisition area of ​​the substrate; when the piezoelectric pixel array is in a receiving state, it is configured to receive an echo signal and output a target object identification signal, wherein the echo signal includes an ultrasonic signal emitted by the piezoelectric pixel array and the piezoelectric auxiliary structure and returned by the target object.

[0029] A piezoelectric pixel array is arranged on the acquisition area of ​​the substrate, and a piezoelectric auxiliary structure is arranged on the non-acquisition area. The ultrasonic waves emitted by the piezoelectric auxiliary structure enhance the sound intensity of the ultrasonic sensor, causing more ultrasonic waves to be emitted towards the target object. Simultaneously, based on the positional relationship between the acquisition and non-acquisition areas, the piezoelectric auxiliary structure can be distributed beside the piezoelectric pixel array. This allows the piezoelectric auxiliary structure to emit ultrasonic waves from beside and near the edges of the piezoelectric pixel array. Combined with the ultrasonic waves emitted by the piezoelectric pixels at the edges of the array, this enhances the sound intensity at the edges of the piezoelectric pixel array. This results in more ultrasonic waves being reflected by the target object, forming more echo signals, which helps improve the signal reception strength at the edges of the piezoelectric pixel array, making the image edges clearer and providing a better foundation for accurate and reliable target object identification.

[0030] Figure 1 This is one of the structural schematic diagrams of an ultrasonic sensor provided in the embodiments of this application. Figure 2 for Figure 1 Top view of the ultrasonic sensor 100. The ultrasonic sensor 100 includes a substrate 110, a piezoelectric pixel array 120, and a piezoelectric auxiliary structure 130.

[0031] Please refer to Figure 1 and Figure 2 The substrate 110 includes a collection area 111 and a non-collection area 112, wherein the non-collection area 112 is located outside the collection area 111. The relationship between the collection area 111 and the non-collection area 112 is as follows: (refer to...) Figure 2 The non-collection area 112 is arranged in a complete circle around the collection area 111; alternatively, the non-collection area 112 may only be arranged in a circle of 1 / N around the collection area 111, where N is a positive number. Furthermore, the collection area 111 and the non-collection area 112 are as follows: Figure 1 and Figure 2 The adjacent structures shown may also have a certain distance between them.

[0032] The piezoelectric pixel array 120 is disposed on the acquisition area 111 of the substrate 110. For example, the piezoelectric pixel array 120 may be completely protruding from or recessed into the substrate 110, or partially protruding and partially recessed into the substrate 110. The piezoelectric pixel array 120 is an array formed by multiple piezoelectric pixels, each of which can emit ultrasonic waves 11 based on the inverse piezoelectric effect and receive echo signals 12 based on the direct piezoelectric effect. When the piezoelectric pixel array 120 participates in imaging, each piezoelectric pixel can serve as an imaging pixel.

[0033] The piezoelectric auxiliary structure 130 can emit ultrasonic waves 11 based on the piezoelectric effect. The piezoelectric auxiliary structure 130 is disposed on the non-collection area 112 of the substrate 110. For example, the piezoelectric auxiliary structure 130 is completely protruding or recessed into the substrate 110, or partially protruding and partially recessed into the substrate 110. The piezoelectric auxiliary structure 130 can be located beside the piezoelectric pixel array 120, so that the piezoelectric auxiliary structure 130 is close to the edge of the piezoelectric pixel array 120, and the ultrasonic waves 11 emitted by the piezoelectric auxiliary structure 130 can be approximately regarded as being emitted from the edge of the piezoelectric pixel array 120, satisfying that the echo signal 12 formed by the ultrasonic waves 11 emitted by the piezoelectric auxiliary structure 130 is received by at least the piezoelectric pixels located at the edge of the piezoelectric pixel array 120.

[0034] Both the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 can operate in a state that emits ultrasonic waves 11. Furthermore, the piezoelectric pixel array 120 can also operate in a state that receives echo signals 12. Specifically, in the emission state, the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 can emit ultrasonic waves 11 towards the target object (simultaneously or at different times). Since the piezoelectric auxiliary structure 130 is located beside the piezoelectric pixel array 120, the ultrasonic waves 11 emitted by the piezoelectric auxiliary structure 130 can be considered as ultrasonic waves 11 emitted from the edge of the piezoelectric pixel array 120. For the edge of the piezoelectric pixel array 120, the emitted ultrasonic waves 11 include those emitted by the piezoelectric pixels at the edge of the piezoelectric auxiliary structure 130 and the piezoelectric pixels in the piezoelectric pixel array 120, thereby increasing the ultrasonic intensity at the edge of the piezoelectric pixel array 120.

[0035] After the ultrasonic wave 11 emitted by the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 propagates to the target object, it is reflected by the target object to form an echo signal 12. Therefore, the echo signal 12 carries the characteristic signals of the target object, such as the aforementioned fingerprint characteristic information, palm print characteristic information, and facial characteristic information.

[0036] The piezoelectric pixel array 120 is switched to receiving mode to receive the echo signal 12. The echo signal 12 returns to the acquisition area 111 and is received by the piezoelectric pixel array 120 in receiving mode. After electromechanical conversion through the piezoelectric effect, a target object identification signal is output. By processing the target object identification signal, the characteristic signal of the target object is extracted to achieve target object identification. For the non-acquisition area 112, regardless of whether there is an echo signal 12 incident, the piezoelectric auxiliary structure 130 does not output a signal for target object identification. In other words, when identifying a target object, it relies on the target object identification signal output by the piezoelectric pixel array 120, and does not rely on the piezoelectric auxiliary structure 130.

[0037] In summary, due to the piezoelectric auxiliary structure 130 at the edge of the piezoelectric pixel array 120, more ultrasonic waves 11 are emitted towards the target object, and more echo signals 12 are reflected back by the target object. Based on the principle of sound wave reflection, the echoes formed by the ultrasonic waves 11 emitted by the piezoelectric auxiliary structure 130 are more concentrated at the edge of the piezoelectric pixel array 120. This allows the piezoelectric pixels at the edge of the piezoelectric pixel array 120 to receive more echo signals 12, increasing the signal strength received at the edge of the piezoelectric pixel array 120 and reducing the difference in signal reception strength between the center and the edge of the piezoelectric pixel array 120. This reduces the differences in brightness and contrast between the image center and the edge, resulting in a more complete and clearer image, especially improving the ridge details at the image edges and corners, providing a better data foundation for accurate target identification.

[0038] Based on the above description, since the piezoelectric pixel array 120 needs to collect the feature signals of the target object for identification, the area on the substrate 110 where the piezoelectric pixel array 120 is located is called the collection area 111; while the piezoelectric auxiliary structure 130 does not need to collect the signals for identification, so the area on the substrate 110 where the piezoelectric auxiliary structure 130 is located is called the non-collection area 112.

[0039] In some possible implementations, the piezoelectric auxiliary structure 130 and the piezoelectric pixel array 120 can simultaneously emit ultrasonic waves 11, and the ultrasonic waves 11 emitted by the two can meet the conditions for constructive interference, such as the frequency and phase of the ultrasonic waves 11 emitted by the two satisfying the interference conditions, so as to have a better gain effect.

[0040] In some possible implementations, please refer to the references. Figure 1 and Figure 2 The piezoelectric pixel array 120 includes a stacked bottom electrode 123, a pixel piezoelectric layer 122, and a top electrode 121. The bottom electrode 123 can be divided into multiple spaced-apart first sub-electrodes 1231, and / or the top electrode 121 can be divided into multiple spaced-apart second sub-electrodes, so that the piezoelectric pixel array 120 is divided into individual piezoelectric pixels according to the first sub-electrodes 1231 or the second sub-electrodes. Figure 1 and Figure 2 In the middle, the bottom electrode 123 is divided into multiple spaced-apart first sub-electrodes 1231 ( Figure 1 Five blocks are shown in the image. Figure 2 (25 are shown in the figure), and the top electrode 121 is a single electrode, and the pixel piezoelectric layer 122 is also a single piezoelectric layer. Each sub-electrode, together with its corresponding (e.g., directly corresponding) portion of the pixel piezoelectric layer 122 and the top electrode 121, forms a piezoelectric pixel. Figure 1 Five piezoelectric pixels are shown. Figure 2 (For example, in the example, 25 piezoelectric pixels are shown); Figure 1 Based on this, the top electrode 121 is divided into multiple second sub-electrodes, the same number as the number of first sub-electrodes 1231 contained in the bottom electrode 123. The first sub-electrodes 1231 in the bottom electrode 123 and the second sub-electrodes in the top electrode 121 are vertically aligned. The vertically aligned first sub-electrodes 1231 and second sub-electrodes, along with the pixel piezoelectric layer 122 between them, constitute a piezoelectric pixel. Furthermore, the pixel piezoelectric layer 122 can be selected as a single piece or divided into multiple spaced-apart blocks as needed (the division principle is the same as that of the top electrode 121, and will not be repeated here).

[0041] In some possible implementations, please continue to refer to Figure 1 and Figure 2 The piezoelectric auxiliary structure 130 includes a stacked lower electrode 133, an auxiliary piezoelectric layer 132, and an upper electrode 131. Two embodiments are shown below: In one implementation, Figure 1 and Figure 2 The diagram shows that the lower electrode 133 and the upper electrode 131 are both integral electrodes, and the auxiliary piezoelectric layer 132 is also an integral piezoelectric layer.

[0042] In another embodiment, when the piezoelectric auxiliary structure 130 is divided into multiple piezoelectric auxiliary units 134, the lower electrode 133 can be divided into multiple spaced-apart lower unit electrodes and / or the upper electrode 131 can be divided into multiple spaced-apart upper unit electrodes. The number of lower unit electrodes or upper unit electrodes is the same as the number of piezoelectric auxiliary units 134, so that the piezoelectric auxiliary structure 130 can be divided into multiple piezoelectric auxiliary units 134 according to the lower unit electrodes or upper unit electrodes. For example, please refer to... Figure 3 The lower electrode 133 is divided into multiple lower unit electrodes spaced apart from each other, and the upper electrode 131 is divided into multiple upper unit electrodes spaced apart from each other. Figure 3 The diagram shows the upper electrode 131 divided into four upper unit electrodes (the lower unit electrodes are not shown due to obstruction). The lower and upper unit electrodes are arranged in a one-to-one correspondence, and the corresponding lower and upper unit electrodes, along with the auxiliary piezoelectric layer 132 between them, constitute a piezoelectric auxiliary unit 134. Furthermore, the auxiliary piezoelectric layer 132 can be selected as a single piece or divided into multiple spaced-apart blocks as needed (the division principle is the same as that of the upper electrode 131 and will not be repeated here).

[0043] It should be understood that the lower electrode 133 may be disposed on the same layer or a different layer from the bottom electrode 123, the auxiliary piezoelectric layer 132 may be disposed on the same layer or a different layer from the pixel piezoelectric layer 122, and the upper electrode 131 may be disposed on the same layer or a different layer from the top electrode 121.

[0044] The piezoelectric auxiliary structure 130 helps improve the signal reception strength at the edges of the piezoelectric pixel array 120, achieving signal gain at the edges. Therefore, the position of the piezoelectric auxiliary structure 130 depends on the edge position of the piezoelectric pixel array 120 where the signal reception strength needs to be improved. The following describes the placement of the piezoelectric auxiliary structure 130 in some embodiments: When there is a gain requirement across the entire periphery of the piezoelectric pixel array 120, the piezoelectric auxiliary structure 130 can be arranged around the periphery of the piezoelectric pixel array 120. Specifically: In one implementation, please refer to Figure 1 and Figure 2 The lower electrode 133 and upper electrode 131 of the piezoelectric auxiliary structure 130 are both annular electrodes, and the auxiliary piezoelectric layer 132 is also an annular piezoelectric layer. The lower electrode 133, the auxiliary piezoelectric layer 132, and the upper electrode 131 are all arranged in a continuous ring around the piezoelectric pixel array 120, so that the piezoelectric auxiliary structure 130 is arranged in a continuous ring around the periphery of the piezoelectric pixel array 120, thereby improving the signal strength that can be received at the entire periphery of the piezoelectric pixel array 120. It should be understood that the annular electrode can be any shape, such as circular, polygonal, or irregular.

[0045] In another implementation, please refer to Figure 3 The piezoelectric auxiliary structure 130 is divided into four piezoelectric auxiliary units 134. The lower unit electrodes of adjacent piezoelectric auxiliary units 134 are spaced apart, and the upper unit electrodes are spaced apart. The four piezoelectric auxiliary units 134 can be arranged intermittently around the periphery of the piezoelectric pixel array 120 so that the entire periphery of the piezoelectric pixel array 120 can obtain the gain of the piezoelectric auxiliary units 134.

[0046] When there is a gain requirement at some edge positions of the piezoelectric pixel array 120, the following example can be used for setting: In one embodiment, the piezoelectric auxiliary structure 130 is divided into a plurality of piezoelectric auxiliary units 134 (the number is determined according to the number of edge positions with gain requirements). The piezoelectric auxiliary units 134 are only provided on the side of the edge positions with gain requirements around the piezoelectric pixel array 120, while no piezoelectric auxiliary units 134 are provided on the side of the edge positions without gain requirements around the piezoelectric pixel array 120.

[0047] Both the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 need to be electrically connected to the circuit structure to facilitate the realization of various states of the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130. The circuit structure includes a driving circuit and a receiving circuit, which will be explained in detail below for ease of understanding: The piezoelectric pixel array 120 is connected to the first circuit 151 and the receiving circuit in the driving circuit, facilitating the operation of the piezoelectric pixel array 120 between the transmitting and receiving states: Please refer to... Figure 4 The first circuit 151 includes a first switch 152 and a second switch 153 connected in series. The second switch 153 is connected in parallel with the top electrode 121 in the piezoelectric pixel array 120 and is grounded. The receiving circuit includes multiple branches connected in parallel, each branch being connected to a first sub-electrode 1231. Each branch includes a third switch 154 and a signal amplifier 155 connected in parallel.

[0048] When the piezoelectric pixel array 120 is in the emission state, the third switch 154 is turned on, the first sub-electrode 1231 is grounded through the turned-on third switch 154, the first switch 152 is turned on and the second switch 153 is turned off, the external voltage (i.e. the driving signal) is applied to the top electrode 121 through the turned-on first switch 152, so that a potential difference is generated between the top electrode 121 and each of the first sub-electrodes 1231, thereby driving the piezoelectric pixel array 120 to emit ultrasonic waves 11.

[0049] When the piezoelectric pixel array 120 is in the receiving state, the first switch 152 is open (disconnecting the external voltage from the electrical connection of the top electrode 121), the second switch 153 is closed (grounding the top electrode 121), and the third switch 154 is open (preventing each of the first sub-electrodes 1231 from being grounded). In this way, after the echo signal 12 is received by the piezoelectric pixel array 120, it can be converted by electromechanical means and output as a target object identification signal through the receiving circuit connected to each of the first sub-electrodes 1231.

[0050] The piezoelectric auxiliary structure 130 is connected to the second circuit 156 in the drive circuit, facilitating the operation of the piezoelectric auxiliary structure 130 in the emission state: Please refer to... Figure 5 As shown in (a), a fourth switch 1561 is provided on the second circuit 156. An external voltage can be connected to the upper electrode 131 via the fourth switch 1561. The external voltage is applied to the upper electrode 131 after the fourth switch 1561 is turned on, generating a potential difference between the upper electrode 131 and the lower electrode 133, thereby driving the piezoelectric auxiliary structure 130 to emit ultrasonic waves 11. Of course, please refer to... Figure 5 In (b), the second circuit 156 can also be connected to the lower electrode 133 of the piezoelectric auxiliary structure 130.

[0051] The first circuit 151 and the second circuit 156 are independent of each other, facilitating independent control of the driving signals of the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130. For example, the driving signals of the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 can be controlled to be the same or different. More specifically, for example, the delay of the driving signal applied to the piezoelectric auxiliary structure 130 can be adjusted by a microcontroller (such as a control chip) so that the ultrasonic signals emitted by the piezoelectric auxiliary structure 130 and the piezoelectric pixel array 120 are superimposed in phase in the edge region of the piezoelectric pixel array 120; or, the voltage amplitude of the driving signal applied to the piezoelectric auxiliary structure 130 can be adjusted to control the intensity of its compensation (ultrasonic sound intensity). It should be understood that the driving signal includes, but is not limited to, one or more of the following: voltage amplitude, pulse width, delay, etc. Therefore, when two driving signals are different, at least one of the following can be different: voltage amplitude, pulse width, delay, etc. For example, the first circuit outputs a first driving signal to the piezoelectric pixel array, and the second circuit outputs a second driving signal to the piezoelectric auxiliary structure, wherein the signal amplitude, pulse width and / or delay of the first driving signal and the second driving signal are different.

[0052] In an optional example, when the second circuit 156 of the driving circuit is connected to the plurality of piezoelectric auxiliary units 134 of the piezoelectric auxiliary structure 130, the driving signals output by the second circuit 156 to the plurality of piezoelectric auxiliary units 134 may be the same or different. For example, the second circuit 156 can output at least two different driving signals to the plurality of piezoelectric auxiliary units to achieve differentiated driving, thereby flexibly adjusting the sound characteristics of the piezoelectric auxiliary units 134 at different positions. It should also be understood that the driving signals include, but are not limited to, one or more combinations of voltage amplitude, pulse width, delay, etc. Therefore, when two driving signals are different, at least one of voltage amplitude, pulse width, delay, etc. may be different. For example, the second circuit can output at least two different second driving signals.

[0053] The piezoelectric auxiliary structure 130 does not output a target object recognition signal, thus preventing it from participating in the imaging of the target object. This avoids the problem of degraded image quality at the edges due to edge effects (less signal reception at the edges). Based on this, the piezoelectric auxiliary structure 130 may output a non-target object recognition signal or not output a signal at all. Specifically: When the piezoelectric auxiliary structure 130 switches to the receiving state, it can receive the echo signal 12 incident on the non-collection area 112 and output a non-target object identification signal. Although this signal does not participate in the identification of the target object, it can serve as the data basis for the implementation of other functions, such as self-testing.

[0054] When the piezoelectric auxiliary structure 130 switches to the non-receiving state, the piezoelectric auxiliary structure 130 does not receive the echo signal 12 incident on the non-collection area 112. Therefore, the piezoelectric auxiliary structure 130 in this state does not output an effective signal.

[0055] When the piezoelectric auxiliary structure 130 is in a non-receiving state, please refer to... Figure 5 As shown in (a), the lower electrode 133 of the piezoelectric auxiliary structure 130 is connected to a fixed reference potential via the auxiliary switch 157. After the fourth switch 1561 is opened and the auxiliary switch 157 is turned on, the lower electrode 133 is connected to the fixed reference potential. At this time, the piezoelectric auxiliary structure 130 is in a non-receiving state. Or, as Figure 5 As shown in (b), the upper electrode 131 of the piezoelectric auxiliary structure 130 is connected to a fixed reference potential via the auxiliary switch 157. After the fourth switch 1561 is opened and the auxiliary switch 157 is turned on, the upper electrode 131 is connected to the fixed reference potential. At this time, the piezoelectric auxiliary structure 130 is in a non-receiving state. Alternatively, please refer to... Figure 5 In (c) of the second circuit 156, a fifth switch 1562 may also be provided. The fifth switch 1562 can be grounded and connected in series with the fourth switch 1561. The fifth switch 1562 is connected in parallel with the upper electrode 131. The on / off states of the fourth switch 1561 and the fifth switch 1562 are opposite so that the external voltage can be smoothly applied to the upper electrode 131. When the piezoelectric auxiliary structure 130 needs to be in a non-receiving state, the fourth switch 1561 is off, the fifth switch 1562 is on, and the auxiliary switch 157 is on.

[0056] In some possible implementations, the reference potential is fixed as ground potential. This allows the upper electrode 131 and / or lower electrode 133 in the piezoelectric auxiliary structure 130 to act as an electrostatic discharge protection structure in the non-emitting state (e.g., non-receiving state), releasing the static charge accumulated in the ultrasonic sensor 100 through grounding, thus providing electrostatic protection.

[0057] In some possible implementations, please refer to Figure 1 and Figure 2 The pixel piezoelectric layer 122 of the piezoelectric pixel array 120 and the auxiliary piezoelectric layer 132 of the piezoelectric auxiliary structure 130 are continuously formed into a single piezoelectric layer. In this way, the pixel piezoelectric layer 122 and the auxiliary piezoelectric layer 132 can be fabricated simultaneously during the fabrication process, which helps to simplify the process.

[0058] In some possible implementations, the pixel piezoelectric layer 122 of the piezoelectric pixel array 120 and the auxiliary piezoelectric layer 132 of the piezoelectric auxiliary structure 130 are spaced apart, thereby forming an air gap between them. This air gap reduces mutual interference between the pixel piezoelectric layer 122 and the auxiliary piezoelectric layer 132 caused by vibration, enabling precise parameter control of the ultrasonic waves 11 emitted by the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130.

[0059] It should be understood that, due to the acoustic impedance mismatch between the air gap and the pixel piezoelectric layer 122 and the auxiliary piezoelectric layer 132, an acoustic wave reflection interface is easily formed here, thereby reflecting the sound waves propagating here, causing changes in the sound wave propagation path and generating noise. Therefore, the following implementation method is provided to improve this: In some possible implementation methods, please refer to Figure 6 When the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 are spaced apart, an acoustic impedance matching layer 142 is filled in the gap (air gap) between the pixel piezoelectric layer 122 and the auxiliary piezoelectric layer 132. The acoustic impedance matching layer 142 can be continuous with the acoustic impedance of the pixel piezoelectric layer 122 and the auxiliary piezoelectric layer 132 respectively, thereby avoiding the formation of an obvious acoustic wave reflection interface.

[0060] In some possible implementations, the circuit structure 150 is disposed on the substrate 110, for example Figure 7 As shown, the circuit structure 150 is located on the side surface of the substrate 110 opposite to the piezoelectric pixel array 120, or the circuit structure 150 is located inside the substrate 110.

[0061] In some possible implementations, the orthographic projection of the piezoelectric auxiliary structure 130 and the orthographic projection of the circuit structure 150 at least partially overlap in the thickness direction of the substrate 110. This allows the piezoelectric auxiliary structure 130 to be placed in the area of ​​the substrate 110 where the circuit structure 150 is arranged, thereby keeping the dimensions of the substrate 110 as constant as possible.

[0062] In some possible implementations, such as Figure 6 or Figure 7 A protective layer 141, which serves to encapsulate and protect, can also be provided on the substrate 110. The protective layer 141 covers the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130.

[0063] In some possible implementations, the pixel piezoelectric layer 122 and / or the auxiliary piezoelectric layer 132 may be made of polyvinylidene fluoride (PVDF) or a composite material thereof.

[0064] In another aspect of this application, a sensor module 200 is provided. Please refer to... Figure 8 This includes a control chip and an ultrasonic sensor 100 of any of the above types.

[0065] Please continue to refer to Figure 8 The control chip is mounted on the substrate 110 of the ultrasonic sensor 100, which allows the control chip to be integrated with the ultrasonic sensor 100 to form an independent device structure, reducing the sensor module 200's dependence on an external processor. The control chip can be covered by a protective layer 141, which provides encapsulation and protection.

[0066] The control chip is electrically connected to the piezoelectric pixel array 120 and / or the piezoelectric auxiliary structure 130 in the ultrasonic sensor 100. For example, the control chip is electrically connected to both the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130, so that the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130 can achieve the aforementioned various working states under the control of the control chip. At the same time, the control chip can also preprocess the electrical signals output by the ultrasonic sensor 100, such as target object recognition signals, before sending them out.

[0067] In other embodiments, the functions of the control chip can also be directly integrated into the ultrasonic sensor.

[0068] In another aspect of this application, an electronic device 300 is provided, comprising: a device body and a data acquisition device, wherein the data acquisition device is disposed on the device body and configured to transmit an ultrasonic wave 11 signal toward the ultrasonic recognition area of ​​the device body and receive an echo signal 12 returned by a target object within the ultrasonic recognition area; the data acquisition device is any of the above-mentioned ultrasonic sensor 100 or sensor module 200.

[0069] In an alternative implementation, the data acquisition device may be disposed on the surface of the electronic device, such as the side or back.

[0070] The aforementioned electronic device 300 may specifically be a mobile phone, tablet computer, television, laptop computer, smart home device (e.g., smart air conditioner, smart refrigerator, smart speaker, smart light or smart curtain, etc.), wearable device, in-vehicle device (also known as vehicle system), virtual reality device, etc., and this application does not impose any restrictions on it.

[0071] Please refer to Figure 9The diagram illustrates a device body with a display screen 310, in which an ultrasonic sensor 100 is disposed below the display screen 310. For example, the surface of the substrate 110 of the ultrasonic sensor 100 facing away from the piezoelectric pixel array 120 is attached to the lower surface of the display screen 310. When a finger 400 comes into contact with the display screen 310 as a target object, the ultrasonic sensor 100 activates and emits ultrasonic waves 11 through the piezoelectric pixel array 120 and the piezoelectric auxiliary structure 130. The ultrasonic waves 11 travel from the substrate 110 through the display screen 310 to the finger 400, are reflected by the finger 400 to form an echo signal 12, and the piezoelectric pixel array 120 receives the echo signal 12 and outputs a target object recognition signal. This signal is processed to form an image of the finger 400, and the finger 400 is recognized based on this image.

[0072] In some possible implementations, an acoustic transition layer 320 may be added between the ultrasonic sensor 100 and the display screen 310 to improve the impedance matching between the ultrasonic sensor 100 and the display screen 310, so as to better guide the ultrasonic waves 11 emitted by the ultrasonic sensor 100 to propagate smoothly to the finger 400.

[0073] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0074] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0075] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0076] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0077] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An ultrasonic sensor, characterized in that, include: The substrate includes a data acquisition area and a non-data acquisition area located around the data acquisition area; A piezoelectric pixel array is disposed on the acquisition area of ​​the substrate; A piezoelectric auxiliary structure is provided on the non-collection area of ​​the substrate; When the piezoelectric pixel array is in receiving mode, it is configured to receive echo signals and output target object identification signals, wherein the echo signals include ultrasonic signals emitted by the piezoelectric pixel array and the piezoelectric auxiliary structure and returned by the target object.

2. The ultrasonic sensor as described in claim 1, characterized in that, When the piezoelectric pixel array is in the receiving state, the piezoelectric auxiliary structure is in the non-receiving state and configured not to receive the echo signal.

3. The ultrasonic sensor as described in claim 2, characterized in that, The piezoelectric auxiliary structure is connected to a fixed reference potential via an auxiliary switch; the auxiliary switch turns on the fixed reference potential so that the piezoelectric auxiliary structure is in a non-receiving state.

4. The ultrasonic sensor as described in claim 3, characterized in that, The fixed reference potential is the ground potential.

5. The ultrasonic sensor as described in claim 3, characterized in that, The piezoelectric auxiliary structure includes a stacked lower electrode, an auxiliary piezoelectric layer, and an upper electrode; when one of the lower electrode and the upper electrode receives a driving signal, the piezoelectric auxiliary structure emits an ultrasonic signal; the other of the lower electrode and the upper electrode is connected to the fixed reference potential via the auxiliary switch.

6. The ultrasonic sensor as described in claim 1, characterized in that, The piezoelectric auxiliary structure is arranged around the periphery of the piezoelectric pixel array.

7. The ultrasonic sensor as described in claim 6, characterized in that, The piezoelectric auxiliary structure is divided into multiple piezoelectric auxiliary units along the periphery of the piezoelectric pixel array, with the upper unit electrodes of adjacent piezoelectric auxiliary units spaced apart and / or the lower unit electrodes spaced apart.

8. The ultrasonic sensor as described in claim 1, characterized in that, The piezoelectric pixel array and the piezoelectric auxiliary structure are arranged continuously or at intervals.

9. The ultrasonic sensor as described in claim 8, characterized in that, When the piezoelectric pixel array and the piezoelectric auxiliary structure are spaced apart, the pixel piezoelectric layer of the piezoelectric pixel array and the auxiliary piezoelectric layer of the piezoelectric auxiliary structure are spaced apart, and an acoustic impedance matching layer is filled at the space between the pixel piezoelectric layer of the piezoelectric pixel array and the auxiliary piezoelectric layer of the piezoelectric auxiliary structure.

10. The ultrasonic sensor according to any one of claims 1 to 9, characterized in that, The ultrasonic sensor also includes a circuit structure, the circuit structure comprising: The driving circuit is electrically connected to the piezoelectric pixel array and the piezoelectric auxiliary structure, respectively; A receiving circuit is electrically connected to the piezoelectric pixel array and disconnected from the piezoelectric auxiliary structure, and the receiving circuit is configured to receive the target object identification signal.

11. The ultrasonic sensor as described in claim 10, characterized in that, When the piezoelectric auxiliary structure is divided into multiple piezoelectric auxiliary units along the periphery of the piezoelectric pixel array, the driving circuit outputs at least two different driving signals to the multiple piezoelectric auxiliary units.

12. The ultrasonic sensor as described in claim 10, characterized in that, The driving circuit includes a first circuit and a second circuit. The first circuit is driven and connected to the piezoelectric pixel array, and the second circuit is driven and connected to the piezoelectric auxiliary structure.

13. The ultrasonic sensor as described in claim 12, characterized in that, The first circuit outputs a first driving signal to the piezoelectric pixel array, and the second circuit outputs a second driving signal to the piezoelectric auxiliary structure, wherein the first driving signal and the second driving signal have different signal amplitudes, pulse widths and / or delays.

14. The ultrasonic sensor as described in claim 10, characterized in that, The circuit structure is located on the substrate, and in the thickness direction of the substrate, the orthographic projection of the piezoelectric auxiliary structure at least partially overlaps with the orthographic projection of the circuit structure.

15. A sensor module, characterized in that, The device includes a control chip and an ultrasonic sensor as described in any one of claims 1 to 14, wherein the control chip is disposed on the substrate of the ultrasonic sensor and is electrically connected to the piezoelectric pixel array and / or piezoelectric auxiliary structure in the ultrasonic sensor.

16. An electronic device, characterized in that, include: The device body and the acquisition device are provided. The acquisition device is disposed on the device body and configured to transmit ultrasonic signals toward the ultrasonic recognition area of ​​the device body and receive echo signals returned by the target object in the ultrasonic recognition area. The acquisition device is the ultrasonic sensor according to any one of claims 1 to 14 or the sensor module according to claim 15.

17. The electronic device as claimed in claim 16, characterized in that, The main body of the device includes a display screen, which has the ultrasonic recognition area, and the acquisition device is located below the display screen.

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