Ultrasonic sensor, sensor module, electronic device, and vehicle

Abstract

An ultrasonic sensor (100), comprising a chip (10) and a piezoelectric resonance unit (20), wherein a piezoelectric layer group (201) of the piezoelectric resonance unit (20) generates ultrasonic waves, which propagate through the chip (10) and each layer of the piezoelectric resonance unit (20), generating resonant superposition; and since the material of a chip substrate (11) of the chip (10) is different from the material of an encapsulation member (12), different superposition effects are generated, and at least two ultrasonic signals of different frequencies are formed after resonant superposition, so that the chip (10) can obtain at least two pieces of biological feature information, enriching the functions of the ultrasonic sensor (100), and meeting the requirements for various application scenarios. Moreover, by means of adjusting and designing the thickness of each layer of the piezoelectric resonance unit (20), the thickness of the chip substrate (11) and the thickness of the encapsulation member (12), the frequency values of the ultrasonic signals can be designed, and the frequencies of the ultrasonic signals can thus be designed, so that different detection functions can be correspondingly realized to match the requirements for different application scenarios, enriching the scenarios to which the ultrasonic sensor (100) can be applied.

Description

Ultrasonic sensor, sensor module, electronic equipment and vehicle

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 14, 2023, with application number 202311730154.1 and application name “Ultrasonic sensor, sensor module, electronic device and vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electronic information technology, and in particular to an ultrasonic sensor, a sensor module, an electronic device, and a vehicle. Background Art

[0003] Ultrasonic sensors convert ultrasonic signals into other energy signals (usually electrical signals). Ultrasonic waves are mechanical waves with a vibration frequency exceeding 20kHz. They have high frequency, short wavelength, minimal diffraction, and, in particular, good directionality, allowing them to propagate in a directional manner as rays. They are widely used in industry, national defense, and biomedicine.

[0004] Ultrasonic fingerprint recognition technology has become a key solution for under-screen fingerprint recognition in electronic devices. Ultrasonic sensors emit ultrasonic waves of a preset frequency, which pass through the device's display, glass cover, and other components before reaching the user's finger. The reflected ultrasound is then received by the ultrasonic sensor, which then detects the user's fingerprint and identifies the fingerprint. With the continuous advancement of biometric detection and recognition technology, some devices require the detection and recognition of multiple biometric features, such as fingerprint recognition and heart rate monitoring. Consequently, an ultrasonic sensor capable of detecting multiple biometric features is needed to meet the needs of different application scenarios. Summary of the Invention

[0005] The embodiments of the present application provide an ultrasonic sensor, a sensor module, an electronic device, and a vehicle. The ultrasonic sensor can emit ultrasonic waves of at least two different frequencies to obtain at least two types of biometric information, meet the needs of monitoring and identifying multiple biometrics, and can correspond to different application scenarios.

[0006] A first aspect of an embodiment of the present application provides an ultrasonic sensor, comprising a chip and a piezoelectric resonance unit. The chip comprises a chip substrate and a package wrapped around the periphery of the chip substrate. The package and the chip substrate are made of different molding materials.

[0007] The piezoelectric resonance unit includes a piezoelectric layer group and a protective layer group, which are stacked in sequence on one side of the chip. The piezoelectric layer group is configured to generate ultrasonic waves, which can propagate toward or away from the chip along the stacking direction. The membrane layer above the piezoelectric layer group (the side facing away from the chip along the stacking direction) and below the piezoelectric layer group (the side facing the chip along the stacking direction), and the chip will form resonance, and then the resonance superposition of ultrasonic waves will occur. Due to the different materials of the chip substrate and the package, the resonance superposition effects generated by the chip substrate and the package are different, so that after the ultrasonic waves pass through the resonance superposition of the chip, the piezoelectric layer group and the protective layer group, at least two ultrasonic signals of different frequencies can be formed.

[0008] At least two ultrasonic signals of different frequencies can be transmitted to the detection site (such as a finger). After being reflected, the ultrasonic signals of different frequencies can be transmitted to the piezoelectric layer group. The piezoelectric layer group is also configured to receive the reflected ultrasonic signals of different frequencies and convert them into electrical signals for transmission to the chip. The chip is configured to obtain at least two types of biometric information corresponding to the electrical signals, thereby realizing the detection of multiple types of biometric information, enriching the functions of the ultrasonic sensor, and meeting the needs of various application scenarios. In other words, using a single ultrasonic sensor can give the device the detection and identification functions of multiple types of biometric information, which helps to reduce the sensor structure within the device, simplify the structural layout design of the device, and reduce the device cost.

[0009] At least two ultrasonic signals of different frequencies include an ultrasonic signal of a preset frequency (i.e., an ultrasonic signal of a target frequency). Each layer in the piezoelectric resonant unit has a corresponding first preset thickness, and the chip substrate and the package have a second preset thickness and a third preset thickness, respectively. The first preset thickness, the second preset thickness, and the third preset thickness are set according to the frequency value of the ultrasonic signal of the preset frequency. In other words, the frequency value of the ultrasonic signal emitted by the ultrasonic sensor can be designed by designing the thickness of each layer in the piezoelectric resonant unit, the thickness of the chip substrate, and the thickness of the package to obtain an ultrasonic signal of the target frequency. Furthermore, it can be ensured that the ultrasonic signal of the target frequency has a strong intensity and a better efficiency, thereby realizing the designability of the ultrasonic signal frequency, thereby realizing different detection functions, matching the requirements of different application scenarios, and enriching the applicable scenarios of the ultrasonic sensor.

[0010] In a possible implementation, the piezoelectric resonance unit satisfies the condition: 0.1≤∑(h i / λ i )≤0.4, where h i is the first preset thickness corresponding to each layer in the piezoelectric resonance unit, λ iThe wavelength of the preset frequency ultrasonic wave in each layer of the piezoelectric resonant unit is determined by the wavelength of the wave. This has a better resonance superposition effect on the ultrasonic wave, further improving the efficiency of the ultrasonic sensor and enhancing the intensity of the emitted ultrasonic signal, thereby improving the detection and recognition performance of the ultrasonic sensor.

[0011] In a possible implementation, the piezoelectric resonance unit satisfies the condition: ∑(h i / λ i )=1 / 4. It has a better resonance superposition effect, obtains better efficiency and stronger strength, and further helps to improve the performance of the ultrasonic sensor.

[0012] In a possible implementation, the ultrasonic sensor satisfies the condition: 0.3≤∑(h i / λ i )+(h a / λ a )≤0.7, where h a is the second preset thickness or the third preset thickness, λ a The wavelength of the preset frequency ultrasonic wave corresponding to the chip substrate or package is beneficial to further enhance the resonance superposition effect, thereby further improving the efficiency of the ultrasonic sensor and the intensity of the ultrasonic wave.

[0013] In a possible implementation, the ultrasonic sensor satisfies the condition: ∑(h i / λ i )+(h a / λ a )=1 / 2. This achieves a more excellent resonance superposition effect, obtains better efficiency and stronger strength, and further helps to improve the performance of the ultrasonic sensor.

[0014] In one possible implementation, the second preset thickness and the third preset thickness are equal, and the chip substrate and package form a chip base of uniform thickness. The thickness of the chip base is negatively correlated with the frequency of the ultrasonic wave of the preset frequency. By adjusting the thickness of the chip base, ultrasonic signals of different frequencies can be obtained, enabling the design of ultrasonic frequencies to meet the needs of different application scenarios.

[0015] In one possible implementation, the third preset thickness is negatively correlated with the frequency of the ultrasonic wave of the preset frequency. Adjusting the thickness of the package can also adjust the frequency of the ultrasonic wave of the preset frequency, thereby increasing the flexibility and applicability of ultrasonic frequency adjustment.

[0016] In one possible implementation, the protective layer group includes a first adhesive layer and a protective layer. The protective layer is arranged on the piezoelectric layer group through the first adhesive layer. The double-layer structure design of the protective layer group increases the number of stacked layers of the piezoelectric resonance unit, which is beneficial to enhancing the resonance superposition effect of the ultrasonic wave, better improving the efficiency and intensity of the ultrasonic signal, and also increasing the flexibility of the design of the frequency value of the ultrasonic signal.

[0017] In addition, when the ultrasonic sensor is formed, the protective layer can be directly bonded to the piezoelectric layer group through the first adhesive layer, which makes the operation more convenient, simplifies the forming steps, and helps reduce the forming production cost and improve the forming production efficiency.

[0018] In a possible implementation, the chip further includes a plurality of first pixel electrodes, and the plurality of first pixel electrodes are arrayed on one surface of the chip substrate.

[0019] The piezoelectric layer group includes a redistribution expansion layer, a piezoelectric layer and an electrode layer stacked in sequence. The electrode layer is used to apply voltage excitation to the piezoelectric layer. The piezoelectric layer is used to emit ultrasonic waves under voltage excitation. The piezoelectric layer is also used to receive reflected ultrasonic signals and convert the ultrasonic signals into electrical signals.

[0020] The redistribution expansion layer covers multiple first pixel electrodes. A plurality of second pixel electrodes distributed in an array are provided on the side of the redistribution expansion layer facing away from the chip. The plurality of second pixel electrodes are correspondingly connected to the plurality of first pixel electrodes to realize electrical signal transmission between the first pixel electrodes and the second pixel electrodes. The piezoelectric layer covers the plurality of second pixel electrodes. The redistribution expansion layer can cover one side of the chip substrate and the package. The redistribution expansion layer can have a larger area than the chip substrate, so that the array area of ​​the second pixel electrodes can be larger than the array area of ​​the first pixel electrodes, so that the electrical signals can fan out from the first pixel electrode array in the chip substrate to the larger area of ​​the second pixel electrode array, decoupling the constraints of the chip substrate area and the identification area area. Increasing the redistribution expansion layer and the second pixel electrode array area can achieve the purpose of increasing the identification area, thereby increasing the identification area without increasing the chip substrate and the first pixel electrode array area, reducing the increase in cost.

[0021] In one possible implementation, the preset frequency ultrasonic wave includes either high-frequency ultrasonic wave or low-frequency ultrasonic wave, with the high-frequency ultrasonic wave having a higher frequency than the low-frequency ultrasonic wave. The chip substrate has a thickness of 200 μm to 50 μm, and the high-frequency ultrasonic wave has a frequency of 8 MHz to 20 MHz or 15 MHz to 25 MHz. By adjusting the chip substrate thickness, the high-frequency ultrasonic wave frequency can be more effectively adjusted to meet the frequency design requirements of high-frequency ultrasonic waves.

[0022] In one possible implementation, the preset frequency ultrasonic wave includes either high-frequency or low-frequency ultrasonic waves, with the high-frequency ultrasonic wave having a higher frequency than the low-frequency ultrasonic wave. The thickness of the package is 50 μm to 150 μm, and the low-frequency ultrasonic wave has a frequency of 8 MHz to 2 MHz. By adjusting the thickness of the package, the frequency of the low-frequency ultrasonic wave emitted by the ultrasonic sensor can be more effectively adjusted to meet the frequency design requirements of low-frequency ultrasonic waves.

[0023] In one possible implementation, the at least two biometric signals include at least one of a fingerprint signal, a heart rate signal, a blood oxygen signal, a blood pressure signal, and a respiratory rate signal.

[0024] A second aspect of an embodiment of the present application provides a sensor module, comprising a control chip and any one of the above-mentioned ultrasonic sensors, wherein the ultrasonic sensor is electrically connected to the control chip.

[0025] A third aspect of an embodiment of the present application provides an electronic device, including a cover and any of the above-mentioned ultrasonic sensors, wherein the ultrasonic sensor is fixed to one side of the cover, and the chip of the ultrasonic sensor is located at an end of the ultrasonic sensor facing away from the cover, or the chip of the ultrasonic sensor is connected to the cover.

[0026] In a possible implementation, a second adhesive layer is further included, and the ultrasonic sensor is fixed to the cover plate via the second adhesive layer, thereby facilitating assembly of the ultrasonic sensor within the device.

[0027] A fourth aspect of an embodiment of the present application provides a vehicle, comprising a cover plate and any one of the above-mentioned ultrasonic sensors, wherein the ultrasonic sensor is fixed to one side of the cover plate, the chip of the ultrasonic sensor is located at an end of the ultrasonic sensor facing away from the cover plate, or the chip of the ultrasonic sensor is connected to the cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a cross-sectional schematic diagram of an ultrasonic sensor provided in an embodiment of the present application assembled in a device;

[0029] FIG2 is a cross-sectional schematic diagram of a fingerprint ultrasonic sensor assembled in a device in the related art;

[0030] FIG3 is a schematic diagram of the cross-sectional structure of an ultrasonic sensor provided in an embodiment of the present application;

[0031] FIG4 is an enlarged schematic diagram of a partial cross-sectional structure of the ultrasonic sensor at the chip and redistribution expansion layer in FIG3 ;

[0032] FIG5 is a schematic diagram of a curve showing how the sound pressure of the ultrasonic sensor in FIG3 changes with the thickness of the chip substrate;

[0033] FIG6 is a schematic structural diagram of another ultrasonic sensor provided in an embodiment of the present application;

[0034] FIG7 is a schematic diagram of a curve showing how the sound pressure of the ultrasonic sensor in FIG6 changes with the thickness of the package;

[0035] FIG8 is a schematic diagram of an assembled cross-sectional structure of the ultrasonic sensor and the device cover in FIG3 ;

[0036] FIG9 is a schematic diagram of loading the ultrasonic sensor excitation signal in FIG8 ;

[0037] FIG10 is a schematic diagram of a circuit connection for receiving an echo signal from the ultrasonic sensor in FIG8 ;

[0038] FIG11 is a schematic diagram of another cross-sectional structure of the assembly of the ultrasonic sensor and the device cover in FIG3 ;

[0039] FIG12 is a schematic diagram of loading the ultrasonic sensor excitation signal in FIG11;

[0040] FIG13 is a flow chart of a detection method using the ultrasonic sensor in FIG3 .

[0041] Explanation of the accompanying drawings: 100-ultrasonic sensor; 10-chip; 11-chip substrate; 111-first pixel electrode; 12-package; 20-piezoelectric resonant unit; 201-piezoelectric layer group; 21-redistribution expansion layer; 211-second pixel electrode; 212-connecting trace; 22-piezoelectric layer; 23-electrode layer; 202-protective layer group; 24-first adhesive layer; 25-protective layer; 200-cover plate; 200a-first surface; 200b-second surface; 300-second adhesive layer. DETAILED DESCRIPTION

[0042] The terms used in the implementation section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.

[0043] The present application provides an ultrasonic sensor capable of transmitting and receiving ultrasonic signals, which can be used to detect biometric information for purposes such as user authentication, unlocking, secure payment, and health tracking and monitoring. This biometric information may include, but is not limited to, fingerprints, palm prints, heart rate, blood pressure, blood oxygen, and imaging of superficial tissues (such as eyes, ears, and nose).

[0044] The ultrasonic sensor can be used in electronic devices to give them the function of biometric detection and identification. The electronic devices may include but are not limited to mobile phones, tablet personal computers, laptop computers, desktop computers, gaming devices, ultra-mobile personal computers (MPCs), netbooks, point of sale (POS) terminals, personal digital assistants (PDAs), in-vehicle electronic devices, wearable devices, bank ATMs, electronic databases, etc.

[0045] For example, in scenarios where ultrasonic sensors are used in wearable devices, the wearable devices can be devices that do not require connection to smart devices such as mobile phones and can independently implement all or part of their functions. For example, they can be smart watches, smart glasses, augmented reality (AR) devices, virtual reality (VR) devices, mixed reality (MR) devices, extended reality (XR) devices, etc. Alternatively, wearable devices can be electronic devices that need to be used in conjunction with smart devices such as mobile phones. For example, they can be smart bracelets, smart jewelry, and other devices used to detect various types of biological signs.

[0046] The ultrasonic sensor can also be used in locking devices, for example, door locks, cabinet locks, etc.

[0047] Ultrasonic sensors can also be used in vehicles, such as smart cars. In some examples, ultrasonic sensors can be installed on car door handles. For example, the ultrasonic sensor can detect and identify fingerprints. When the driver grips the handle, the ultrasonic sensor can identify the driver's fingerprint and authenticate their identity, allowing them to open the door, eliminating the need to carry car keys. In some examples, ultrasonic sensors can also be installed on the start button. When the driver presses the start button, the ultrasonic sensor can identify the fingerprint and authenticate the driver's identity, thus enabling the engine to ignite and start the car, improving vehicle safety.

[0048] The ultrasonic sensor can be connected to the vehicle's control unit. The ultrasonic sensor can detect biometric information (such as fingerprint information) and implement storage, comparison and identification of the biometric information. Alternatively, the ultrasonic sensor can also transmit the biometric information to the control unit, and the control unit can implement storage, comparison and identification based on the biometric information. In some examples, the fingerprint information of multiple drivers can be recorded through the ultrasonic sensor and stored in the control unit or ultrasonic sensor. The control unit can also store the setting habit information of multiple drivers during the driving process. The setting habit information can be cockpit setting information, such as seat positioning setting information, rearview mirror angle setting information, etc. When using the vehicle, the ultrasonic sensor set on the door handle, start button or other locations of the wheel can identify and authenticate the driver, so that the control unit can load the setting habit information of the corresponding driver, avoiding repeated adjustments and improving the user experience.

[0049] In some examples, ultrasonic sensors can be used alone in the various devices described above. Alternatively, in some examples, ultrasonic sensors can be integrated into chips to form ultrasonic sensor modules for use in the various devices described above. For example, the ultrasonic sensor module can include an ultrasonic sensor and a control chip, which are electrically connected to the ultrasonic sensor and the control chip. The control chip can be used to implement functions such as timing control, image processing, and comparison recognition, and the control chip can be electrically connected to a control unit of the device.

[0050] FIG1 is a cross-sectional schematic diagram of an ultrasonic sensor provided in an embodiment of the present application assembled in a device.

[0051] The ultrasonic sensor 100 can be integrated inside the above-mentioned electronic equipment, vehicles and other equipment. Taking the ultrasonic sensor 100 set in an electronic device as an example, as shown in Figure 1, the electronic device may include a shell (not shown in the figure) and a cover 200. The cover 200 is covered on the shell to enclose a storage space, and the ultrasonic sensor 100 can be set in the storage space.

[0052] The cover plate 200 may be a light-transmitting structural member, or it may be an opaque structural member. The cover plate 200 may be formed of a single material, for example, the cover plate 200 may be a plate-shaped structural member formed of glass, metal, or polymer. Alternatively, the cover plate 200 may be formed of a multi-layer film composite structure, for example, the cover plate 200 may be a display screen of an electronic device, formed by stacking multiple film layers.

[0053] In the embodiment of the present application, the thickness direction of the cover plate 200 is taken as the x-direction, as shown in FIG1 . The cover plate 200 may include two surfaces opposite to each other in the thickness direction, for example, a first surface 200 a and a second surface 200 b . The first surface 200 a may face the interior of the device, and the second surface 200 b may have a detection area for placing a detection part (such as a finger 400 ), thereby realizing the monitoring of biometric information.

[0054] For example, the ultrasonic sensor 100 can be mounted on the first surface 200a of the cover 200. When biometric detection and identification is required, for example, as shown in FIG1 , where the detection site is a finger 400, and biometrics such as fingerprints and heart rate are detected, the finger 400 can be placed on the second surface 200b of the cover 200. The ultrasonic sensor 100 transmits an ultrasonic signal, which passes through the cover 200 and reaches the finger 400. The finger 400 may reflect some of the ultrasonic signal, which then passes through the cover 200 and is received by the ultrasonic sensor 100. Because different fingerprints have different ridge and valley distributions, their reflection of ultrasonic waves varies. Accordingly, ultrasonic signals can penetrate the epidermis of the finger and reach the subcutaneous tissue. Changes in heart rate also affect the reflection of ultrasonic waves. Therefore, the ultrasonic sensor can obtain biometric information such as fingerprint information and heart rate information based on the reflected ultrasonic signal, thereby enabling fingerprint detection based on fingerprint information and heart rate detection based on heart rate information.

[0055] It is understandable that different biometric detection methods require different ultrasonic frequencies to achieve good accuracy. For example, when detecting epidermal structures like fingerprints and palm prints, the required ultrasonic frequency is relatively high (high-frequency ultrasound), and the ultrasonic wave has relatively low penetration, allowing more of it to reach the epidermis and be reflected. When detecting subcutaneous tissue, such as heart rate, blood pressure, and blood oxygen, the required ultrasonic frequency is relatively low (low-frequency ultrasound), and the ultrasonic wave has relatively high penetration, allowing more of it to pass through the epidermis and reach the subcutaneous tissue.

[0056] FIG2 is a cross-sectional schematic diagram of a fingerprint ultrasonic sensor assembled in a device in the related art.

[0057] Ultrasonic sensors for fingerprint detection often use a sandwich-type single piezoelectric structure. For example, as shown in FIG2 , a fingerprint ultrasonic sensor may include a chip 110. A first electrode layer 120, a piezoelectric material layer 130, a second electrode layer 140, and a protective layer 150 may be sequentially stacked on one side of the chip 110. The other side of the chip 110 may be secured to a cover plate 210 via an adhesive layer 301. The piezoelectric material layer 130 may be composed of a piezoelectric material. The second electrode layer 140 may couple an electrical signal to the piezoelectric material layer 130. The piezoelectric material in the piezoelectric material layer 130 deforms and vibrates under voltage excitation through the inverse piezoelectric effect, thereby emitting ultrasonic waves. Ultrasonic waves reflected by the fingerprint reach the piezoelectric material layer 130, causing it to deform and vibrate. The piezoelectric effect generates a corresponding electrical signal, which can be transmitted to the chip via the first electrode layer 120 to form fingerprint information, thereby enabling fingerprint detection and recognition.

[0058] This fingerprint ultrasonic sensor, used for fingerprint detection, primarily emits high-frequency ultrasonic waves, which are not well suited for detecting subcutaneous tissue-related biometrics such as heart rate, blood pressure, and blood oxygen levels, resulting in a relatively limited functionality. In scenarios where devices require multiple biometric detection and recognition functions, such as fingerprint recognition and heart rate monitoring, multiple sensors are typically integrated within the device to detect each biometric separately. This results in a complex and costly design. Therefore, there is an urgent need for an ultrasonic sensor capable of detecting multiple biometrics.

[0059] Based on this, an embodiment of the present application provides an ultrasonic sensor, which includes a chip and a piezoelectric resonance unit arranged on the chip. The piezoelectric layer group of the piezoelectric resonance unit generates ultrasonic waves. The ultrasonic waves propagate through the layers of the chip and the piezoelectric resonance unit to resonate and superimpose. The chip substrate and the package molding materials of the chip are different, and the chip substrate and the package have different resonance superposition effects on the ultrasonic waves, which can form at least two ultrasonic signals of different frequencies, thereby enabling the chip to obtain at least two biometric information. That is, one ultrasonic sensor can realize the detection of multiple biometric information, enrich the functions of the ultrasonic sensor, meet the needs of various application scenarios, and help reduce the sensor structure in the device, simplify the structural design and reduce costs.

[0060] Moreover, by adjusting the thickness of each layer in the piezoelectric resonant unit, the thickness of the chip substrate and the thickness of the package, the frequency value of the ultrasonic signal can be designed, and the ultrasonic signal of the target frequency can be obtained. It can also be ensured that the ultrasonic wave of the target frequency has a strong intensity and better efficiency, and the frequency of the ultrasonic signal can be designed to realize different detection functions, thereby matching the needs of different application scenarios and enriching the applicable scenarios of ultrasonic sensors.

[0061] FIG3 is a schematic diagram of the cross-sectional structure of an ultrasonic sensor provided in an embodiment of the present application.

[0062] As shown in Figure 3, the ultrasonic sensor 100 includes a chip 10. The chip 10 may include a chip substrate 11 and a package 12. The package 12 can be wrapped around the periphery of the chip substrate 11 to provide packaging and protection for the chip substrate 11, the circuits and electronic devices on the chip substrate 11, etc. For example, pixel circuit electrodes, analog and digital module circuit units, etc. can be set on the substrate chip 10.

[0063] The molding material of the chip substrate 11 is different from the molding material of the package 12. It can be understood that since the molding material of the chip substrate 11 is different from the molding material of the package 12, the ultrasonic signal propagates at different speeds in the chip substrate 11 and the package 12, respectively, and the chip substrate 11 and the package 12 have different reflections and absorptions of ultrasonic waves.

[0064] Illustratively, the molding material of the chip substrate 11 may include one or more of glass, silicon wafer, polyimide (PI), polyethylene terephthalate (PET), and the like.

[0065] The molding material of the package 12 may include plastic, resin, etc. For example, the molding material of the package 12 may be epoxy resin (exopy).

[0066] The ultrasonic sensor 100 also includes a piezoelectric resonant unit 20, which is disposed on one surface of the chip 10. Specifically, the piezoelectric resonant unit 20 and the chip 10 are stacked. The stacking direction can be consistent with the thickness direction of the cover plate 200, such as the x-direction shown in FIG3 . The chip 10 has two opposing surfaces along the stacking direction (x-direction), such as a third surface and a fourth surface. For example, the piezoelectric resonant unit 20 can be located on the third surface of the chip 10.

[0067] The piezoelectric resonance unit 20 may include a piezoelectric layer group 201 and a protective layer group 202. The piezoelectric layer group 201 and the protective layer group 202 are stacked in sequence along the stacking direction. The protective layer group 202 can isolate and protect the piezoelectric layer group 201 to ensure the stability of the piezoelectric resonance unit and the entire ultrasonic sensor.

[0068] The piezoelectric layer group 201 may be a layered structure formed by stacking multiple film layers along a stacking direction. The piezoelectric layer group 201 is capable of generating ultrasonic waves. For example, the piezoelectric layer group 201 may include a piezoelectric layer 22 and an electrode layer 23. The piezoelectric layer 22 is capable of deforming and vibrating under voltage excitation from the electrode layer 23 to generate ultrasonic waves. Ultrasonic waves can propagate along the stacking direction toward or away from the chip 10. The film layers above (on the side facing away from the chip 10 along the stacking direction) and below (on the side facing the chip 10 along the stacking direction) the piezoelectric layer 22 in the piezoelectric resonant unit 20, as well as the chip 10, resonate, resulting in superimposed ultrasonic resonances, which helps improve the transmission efficiency and intensity of ultrasonic signals.

[0069] Since the chip substrate 11 and the package 12 are made of different materials, the resonance superposition effects produced by the chip substrate 11 and the package 12 are different, so that the ultrasonic waves generated by the piezoelectric layer 22 can form at least two ultrasonic signals of different frequencies after being resonantly superimposed by the chip 10, the piezoelectric layer group 201 and the protective layer group 202.

[0070] At least two ultrasonic signals of different frequencies can be transmitted to the detection site (such as a finger). After being reflected, the ultrasonic signals of different frequencies can be transmitted to the piezoelectric layer group 201. The piezoelectric layer group 201 receives the reflected ultrasonic signals of different frequencies and converts them into electrical signals, which are transmitted to the chip 10. The chip 10 can obtain at least two types of biometric information based on the electrical signals, thereby realizing the detection of multiple types of biometric information and enriching the functionality of the ultrasonic sensor 100. Therefore, using a single ultrasonic sensor 100 can give the device the ability to detect and identify multiple types of biometric information, meeting the needs of various application scenarios, reducing the number of sensor structures within the device, simplifying the device's structural layout design, and reducing device costs.

[0071] Among them, the frequency value of the ultrasonic signal emitted by the ultrasonic sensor 100 is designable. For example, the at least two ultrasonic waves of different frequencies emitted by the ultrasonic sensor 100 include a preset frequency ultrasonic wave, which can be the working frequency (i.e., the target frequency) required to realize one of the biometric detections.

[0072] It should be noted that the at least two ultrasonic signals of different frequencies emitted by the ultrasonic sensor 100 may include a low-frequency ultrasonic signal and a high-frequency ultrasonic signal, and the frequency of the high-frequency ultrasonic signal may be higher than that of the low-frequency ultrasonic signal. When designing the ultrasonic signal frequency of the ultrasonic sensor 100, the piezoelectric resonant unit 20 and the chip 10 produce the same resonant superposition effect on the low-frequency ultrasonic signal and the high-frequency ultrasonic signal. The preset ultrasonic frequency may be either a low-frequency ultrasonic signal or a high-frequency ultrasonic signal.

[0073] The frequency value of the preset frequency ultrasonic wave can be selected and set according to actual needs. For example, when the primary function of the ultrasonic sensor 100 is to detect and identify fingerprints, the preset frequency ultrasonic wave can be a high-frequency ultrasonic wave, such as the frequency of the preset frequency ultrasonic wave can be any frequency between 8 MHz and 25 MHz. For example, when the primary function of the ultrasonic sensor 100 is to detect heart rate, the preset frequency ultrasonic wave can be a low-frequency ultrasonic wave, such as the frequency of the preset frequency ultrasonic wave can be any frequency between 5 MHz and 10 MHz.

[0074] In the embodiment of the present application, the thickness of the membrane layer refers to the thickness along the stacking direction. For example, each layer in the piezoelectric resonant unit 20 has a corresponding first preset thickness, that is, each layer in the piezoelectric resonant unit 20 has a corresponding first preset thickness. The chip substrate 11 has a second preset thickness, and the package 12 has a third preset thickness. The first preset thickness, the second preset thickness, and the third preset thickness can be designed according to the frequency value of the preset frequency ultrasonic wave. That is, by designing the thickness of each layer in the piezoelectric resonant unit 20, the thickness of the chip substrate 11, and the thickness of the package 12, the frequency value of the ultrasonic signal emitted by the ultrasonic sensor 100 can be designed, and an ultrasonic signal of the target frequency (that is, an ultrasonic wave of the preset frequency) can be obtained, and it can be ensured that the ultrasonic signal of the target frequency has a strong intensity and a better efficiency, so that the frequency of the ultrasonic signal can be designed, thereby realizing different detection functions, matching the needs of different application scenarios, and enriching the applicable scenarios of the ultrasonic sensor 100.

[0075] For example, low-frequency and high-frequency ultrasound can be used in different application scenarios to enable the ultrasonic sensor 100 to achieve different detection functions. For example, a high-frequency ultrasonic signal can be reflected by a fingerprint on the surface of a finger. The reflected high-frequency ultrasonic signal is received by the piezoelectric layer and converted into an electrical signal. The chip can then obtain a fingerprint signal based on this electrical signal to detect and identify fingerprints on the surface of the finger.

[0076] Low-frequency ultrasonic signals can pass through the finger's epidermis and be reflected by the subcutaneous tissue. The reflected low-frequency ultrasonic signals are received by the piezoelectric layer and converted into electrical signals. Based on these electrical signals, the chip can obtain biometric characteristics related to the subcutaneous tissue, such as heart rate, blood oxygen, and blood pressure. Alternatively, low-frequency ultrasonic signals can pass through the finger's epidermis and be reflected by the dermis to obtain dermal image signals, enabling dermal image detection.

[0077] The protective layer assembly 202 may include a first adhesive layer 24 and a protective layer 25. The protective layer 25 provides isolation and protection for the piezoelectric layer assembly 201. The first adhesive layer 24 is used to secure the protective layer 25 to the piezoelectric layer assembly. For example, the first adhesive layer 24 is located between the protective layer 25 and the piezoelectric layer assembly 201. The protective layer 25 is disposed on the side of the piezoelectric layer assembly 201 facing away from the chip 10 via the first adhesive layer 24. The protective layer assembly 202 has a two-layer structure, which increases the number of layers in the piezoelectric resonant unit 20, enhances the resonant superposition effect of ultrasonic waves, improves the efficiency and intensity of ultrasonic signals, and increases flexibility in designing the frequency value of ultrasonic signals.

[0078] When the ultrasonic sensor 100 is formed, the protective layer 25 can be directly bonded to the piezoelectric layer group 201 through the first adhesive layer 24. Compared with forming an adhesive protective layer 25 on the piezoelectric layer group 201 by deposition or other methods, directly bonding the protective layer 25 to the piezoelectric layer group 201 through the first adhesive layer 24 is more convenient to operate, simplifies the molding steps, and helps reduce molding production costs and improve molding production efficiency.

[0079] For example, the protective layer 25 and the first adhesive layer 24 can be made of different materials. For example, the protective layer 25 can be made of a relatively high-hardness material, while the first adhesive layer 24 can be made of a relatively low-hardness material with relatively high adhesion. The materials and thicknesses of the protective layer 25 and the first adhesive layer 24 also affect the resonant superposition effect of the ultrasonic waves. Adjusting the materials and thicknesses of the protective layer 25 and the first adhesive layer 24 can change the resonant superposition effect, thereby improving the efficiency and intensity of the ultrasonic signal and further increasing the flexibility in designing the frequency value of the ultrasonic signal.

[0080] In some examples, the first adhesive layer 24 and the protective layer 25 can be integrally formed to form a one-piece structure. The first adhesive layer 24 can be located on one side of the protective layer 25, so that the one-piece structure has properties similar to a tape, with one side being the first adhesive layer 24 and the other side being the protective layer 25. When the ultrasonic sensor 100 is formed, the one-piece structure can be directly bonded to the piezoelectric layer assembly 201.

[0081] Of course, in some examples, the first adhesive layer 24 and the protective layer 25 can also be two independent structural parts. When the ultrasonic sensor 100 is formed, the first adhesive layer 24 can be bonded to the protective layer 25 or one of the piezoelectric layer groups 201, and then the protective layer 25 can be bonded to the piezoelectric layer group 201.

[0082] 3 , the piezoelectric layer group 201 includes a stacked piezoelectric layer 22 and an electrode layer 23 . The molding material of the piezoelectric layer 22 includes a piezoelectric material, which is a crystalline material that generates a voltage between its two end faces when subjected to pressure.

[0083] For example, the molding material of the piezoelectric layer 22 may include, but is not limited to, organic polymer piezoelectric materials such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene, or inorganic piezoelectric materials such as lead zirconate titanate piezoelectric ceramics (PZT) and aluminum nitride (AlN).

[0084] The molding material of the electrode layer 23 may include a conductive material, for example, a metal material, such as a film layer formed of a metal material such as silver, copper, etc.

[0085] The electrode layer 23 applies a voltage to the piezoelectric layer 22. Upon receiving the voltage, the piezoelectric layer 22 deforms and vibrates through the inverse piezoelectric effect, thereby generating ultrasonic waves. Conversely, through the piezoelectric effect, the piezoelectric layer 22 receives ultrasonic waves and converts them into electrical signals, which are then transmitted to the chip 10 to obtain biometric information.

[0086] FIG4 is an enlarged schematic diagram of a partial cross-sectional structure of the ultrasonic sensor at the chip and redistribution expansion layer positions in FIG3 .

[0087] As shown in Figure 4, the chip 10 can also include multiple first pixel electrodes 111, and the multiple first pixel electrodes 111 are arrayed on one side of the chip substrate 11. It can be understood that the multiple first pixel electrodes 111 can be located on a side of the chip substrate 11 that is on the same side as the third surface of the chip 10.

[0088] It should be noted that in ultrasonic sensors in related technologies, the electrical signal converted by the piezoelectric layer is transmitted to the chip's first pixel electrode to achieve biometric information recognition. The size of the ultrasonic sensor's recognition area is closely related to the area of ​​the first pixel electrode array on the chip. If the chip substrate and the multiple first pixel electrode arrays on the chip substrate are relatively small, the recognition area will be small, making it difficult to obtain sufficient biometric feature points, which will greatly weaken the recognition function. To improve the detection and recognition capabilities of the ultrasonic sensor, the recognition area needs to be increased, which also requires increasing the chip substrate area, which will increase costs.

[0089] Therefore, in an embodiment of the present application, as shown in Figure 4, the piezoelectric layer group may further include a redistribution expansion layer 21, and the redistribution expansion layer 21 is located between the third surface of the chip 10 and the piezoelectric layer 22 (as shown in Figure 3), that is, the redistribution expansion layer 21, the piezoelectric layer 22, the electrode layer 23, the first adhesive layer 24, and the protective layer 25 are stacked in sequence on the third surface of the chip 10.

[0090] 4 , the redistribution expansion layer 21 is disposed on the third surface of the chip 10 , covers the chip substrate 11 and the package 12 , and covers the multiple first pixel electrodes 111 on the chip substrate 11 .

[0091] The ultrasonic sensor 100 may also include multiple second pixel electrodes 211, and the multiple second pixel electrodes 211 are arrayed on the side of the redistribution expansion layer 21 facing away from the chip 10, that is, the second pixel electrodes 211 are located between the redistribution expansion layer 21 and the piezoelectric layer 22, and the piezoelectric layer 22 can cover the multiple second pixel electrodes 211.

[0092] Multiple first pixel electrodes 111 and multiple second pixel electrodes 211 can be electrically connected to each other. For example, multiple connecting wires 212 can be provided in the redistribution expansion layer 21. Multiple first pixel electrodes 111 can be connected to multiple second pixel electrodes 211 one by one through the connecting wires 212 to realize electrical signal transmission between the first pixel electrodes 111 and the second pixel electrodes 211.

[0093] Exemplarily, the second pixel electrode 211 can receive the electrical signal of the piezoelectric layer, and can realize point-by-point image restoration through pixelation to obtain image information of the biometric feature, and transmit it to the first pixel electrode 111 of the chip 10 .

[0094] The molding materials of the first pixel electrode 111 and the second pixel electrode 211 may both include a conductive material. The molding materials of the first pixel electrode 111 and the second pixel electrode 211 may be the same or different. Exemplarily, the molding materials of the first pixel electrode 111 and the second pixel electrode 211 may include a conductive material such as indium tin oxide (ITO), aluminum (Al), or copper (Cu).

[0095] The redistribution expansion layer 21 covers one side of the chip substrate 11 and the package 12. The redistribution expansion layer 21 can have a larger area than the chip substrate 11, so that the array area of ​​the second pixel electrode 211 can be larger than the array area of ​​the first pixel electrode 111, so that the electrical signal can fan out from the first pixel electrode 111 array in the chip substrate 11 to the second pixel electrode 211 array with a larger area, decoupling the constraints of the chip substrate 11 area and the identification area area, and increasing the redistribution expansion layer 21 and the second pixel electrode 211 array area can achieve the purpose of increasing the identification area, thereby increasing the identification area without increasing the chip substrate 11 and the first pixel electrode 111 array area, thereby reducing the increase in cost.

[0096] By increasing the area of ​​the redistribution expansion layer 21 and the second pixel electrode 211 array, the ultrasonic sensor can have a larger recognition area, which can improve the detection sensitivity and accuracy of the ultrasonic sensor, facilitate "one-click entry" of fingerprints, etc., and also help optimize the user experience in scenarios such as unlocking through fingerprints, etc.

[0097] The following describes an example of designing the frequency of the ultrasonic signal emitted by the ultrasonic sensor 100. It should be noted that the thickness of each structural membrane layer and the molding material in the ultrasonic sensor affect the resonant superposition effect of the ultrasonic waves, thereby affecting the frequency of the ultrasonic signal. For example, the frequency of the ultrasonic signal can be designed by adjusting the thickness of each structural membrane layer so that the ultrasonic sensor can emit an ultrasonic signal of a preset frequency (i.e., an ultrasonic signal of a target frequency).

[0098] The relationship between the thickness of each layer in the piezoelectric resonance unit 20 and the preset frequency ultrasonic wave can satisfy 0.1≤∑(h i / λ i )≤0.4,h i is the first preset thickness corresponding to each layer in the piezoelectric resonance unit 20, λ i is the wavelength corresponding to the preset frequency ultrasonic wave in each layer of the piezoelectric resonance unit 20 .

[0099] Referring back to FIG. 3 , for example, the thickness of the redistribution and expansion layer 21 may be h1, the wavelength of the ultrasonic wave of the preset frequency in the redistribution and expansion layer 21 may be λ1, the thickness of the piezoelectric layer 22 may be h2, the wavelength of the ultrasonic wave of the preset frequency in the piezoelectric layer 22 may be λ2, the thickness of the electrode layer 23 may be h3, the wavelength of the ultrasonic wave of the preset frequency in the redistribution and expansion layer 21 may be λ3, the thickness of the first adhesive layer 24 may be h4, the wavelength of the ultrasonic wave of the preset frequency in the first adhesive layer 24 may be λ4, the thickness of the protective layer 25 may be h5, the wavelength of the ultrasonic wave of the preset frequency in the protective layer 25 may be λ5, and the range of h1 / λ1+h2 / λ2+h3 / λ3+h4 / λ4+h5 / λ5 is 0.1 to 0.4. This has a better resonant superposition effect on the ultrasonic wave, further improving the efficiency of the ultrasonic sensor 100 and enhancing the intensity of the emitted ultrasonic signal, thereby improving the detection and recognition performance of the ultrasonic sensor 100.

[0100] The wavelength of the preset frequency ultrasonic wave in each film layer can be obtained by λ=v / f, where λ is the wavelength, v is the propagation speed of the preset frequency ultrasonic wave in the film layer, and f is the preset frequency.

[0101] It is understandable that the superposition of ultrasonic waves on a theoretically perfect acoustic path may be inconsistent with the design of the target frequency (i.e., the preset frequency), and the specific implementation can be selected according to actual needs.

[0102] For example, the piezoelectric resonance unit 20 may satisfy Σ(h i / λ i )=1 / 4, as described above, h1 / λ1+h2 / λ2+h3 / λ3+h4 / λ4+h5 / λ5=1 / 4, which has a better resonance superposition effect, obtains better efficiency and stronger strength, and further helps to improve the performance of the ultrasonic sensor 100.

[0103] The relationship between the thickness of each layer in the piezoelectric resonant unit 20, the thickness of the chip substrate 11, the thickness of the package 12 and the preset frequency ultrasonic wave can satisfy 0.3≤∑(h i / λ i )+(h a / λ a )≤0.7, where h a is the second preset thickness of the chip substrate 11 or the third preset thickness of the package 12, λ a is the wavelength of the preset frequency ultrasonic wave corresponding to the chip substrate 11 or the package 12. For example, h a can be the thickness of the chip substrate 11, λ a is the wavelength of the preset frequency ultrasonic wave in the chip substrate 11, h1 / λ1+h2 / λ2+h3 / λ3+h4 / λ4+h5 / λ5+ha / λ a The range of is 0.3 to 0.7, which is beneficial to further enhance the resonance superposition effect, thereby further enhancing the efficiency of the ultrasonic sensor 100 and the intensity of the ultrasonic wave.

[0104] It should be noted that the second preset thickness of the chip substrate 11 and the third preset thickness of the package 12 will affect the frequency value of the ultrasonic signal. For example, in some examples, the thicknesses of the chip substrate 11 and the package 12 can be adjusted as a whole to achieve the design of the frequency value. The second preset thickness of the chip substrate 11 can be consistent with the third preset thickness of the package 12. The above h a It can be any one of the second preset thickness of the chip substrate 11 and the third preset thickness of the package 12. In some examples, the thickness of the chip substrate 11 or the package 12 can also be adjusted independently to achieve the design of the frequency value. a The preset thickness of the chip substrate 11 or the package 12 may be adjusted. For example, the frequency value can be adjusted by adjusting the thickness of the package 12. a The package 12 may have a third predetermined thickness.

[0105] For example, the ultrasonic sensor 100 may satisfy Σ(h i / λ i )+(h a / λ a )=1 / 2, as mentioned above h1 / λ1+h2 / λ2+h3 / λ3+h4 / λ4+h5 / λ5+h a / λ a =1 / 2. This achieves a more excellent resonance superposition effect, obtains better efficiency and stronger strength, and further helps to improve the performance of the ultrasonic sensor 100.

[0106] It should be noted that the frequency of the ultrasonic signal can be adjusted by adjusting the thickness of any one or several of the layers in the piezoelectric resonant unit 20, the chip substrate 11 and the package 12. That is to say, the frequency value of the ultrasonic signal emitted by the ultrasonic sensor 100 can be adjusted by adjusting the thickness of any one or several of the chip substrate 11, the package 12, the redistribution expansion layer 21, the piezoelectric layer 22, the electrode layer 23, the first adhesive layer 24 and the protective layer 25.

[0107] For example, the frequency of the preset ultrasonic wave can be adjusted by adjusting the thickness of the chip substrate 11 and the package 12 as a whole, so as to obtain ultrasonic waves of different frequencies to match the requirements of different application scenarios.

[0108] For example, in some examples, the chip substrate 11 and the package 12 can have the same thickness, so that the chip substrate 11 and the package 12 can form a chip base 10a of uniform thickness (see FIG3 ). By adjusting the thickness of the chip substrate 11 and the package 12 as a whole, the frequency value and intensity of the preset frequency ultrasonic wave can be adjusted.

[0109] FIG. 5 is a schematic diagram of a curve showing how the sound pressure of the ultrasonic sensor in FIG. 3 changes with the thickness of the chip substrate.

[0110] 5 , by changing the thickness of the chip substrate 10 a and applying the same voltage excitation, the ultrasonic sound pressure pattern emitted by the ultrasonic sensor shows that, for example, multiple frequency peaks appear within the 25 MHz range.

[0111] As shown in FIG5 , the thickness of the chip substrate 10 a is negatively correlated with the frequency of the preset frequency ultrasonic wave. As the thickness of the chip substrate 10 a decreases, the frequency value of the preset frequency ultrasonic wave increases. By adjusting the thickness of the chip substrate 10 a, the frequency can be designed within a certain range, and ultrasonic signals of different frequencies can be obtained, thereby meeting the needs of different application scenarios.

[0112] 5 , if the ultrasonic wave with a frequency range of 8 MHz to 25 MHz is taken as the high-frequency ultrasonic wave, as the thickness of the chip substrate 10 a changes, the ultrasonic wave frequency is within the range of 10 MHz to 25 MHz, and the frequency value changes more obviously. That is, by adjusting the overall thickness of the chip substrate 10 a, the frequency value of the high-frequency ultrasonic wave can be more effectively adjusted to meet the frequency design requirements of the high-frequency ultrasonic wave.

[0113] Exemplarily, the thickness of the chip substrate 10a can vary within the range of 200 μm to 50 μm (inclusive), and the frequency of the high-frequency ultrasound can vary within the range of 8 MHz to 20 MHz (inclusive) and 15 MHz to 25 MHz (inclusive).

[0114] For example, see Figure 5. The E+Si120, E+Si140, E+Si160, and E+Si180 curves are acoustic pressure curves for substrate thicknesses of 120 μm, 140 μm, 160 μm, and 180 μm, respectively. As the substrate thickness decreases from 180 μm to 120 μm, the frequency of the high-frequency ultrasonic wave changes from 16.3 MHz to 22.8 MHz, and from 11 MHz to 14.6 MHz.

[0115] For example, the frequency of the preset ultrasonic wave can be adjusted by adjusting the thickness of the package 12 to obtain ultrasonic waves of different frequencies to meet the needs of different application scenarios.

[0116] FIG6 is a schematic structural diagram of another ultrasonic sensor provided in an embodiment of the present application.

[0117] The thickness of the package 12 is changed. In one possible example, as shown in FIG6 , the thickness of the package 12 may be inconsistent with the thickness of the chip substrate 11 . Of course, in some other examples, the thickness of the package 12 may also be consistent with the thickness of the chip substrate 11 .

[0118] FIG. 7 is a schematic diagram of a curve showing how the sound pressure of the ultrasonic sensor in FIG. 6 changes with the thickness of the package.

[0119] As shown in Figure 7, by changing the thickness of the package 12, after applying the same voltage excitation, the frequency value of the preset frequency ultrasonic wave is changed. The thickness of the package 12 is negatively correlated with the frequency of the preset frequency ultrasonic wave. As the thickness of the package 12 increases, the frequency value of the preset frequency ultrasonic wave decreases, thereby realizing the design of the preset frequency ultrasonic wave frequency to match the requirements of different application scenarios, improve the detection performance, and expand the scope of applicability.

[0120] Among them, referring to Figure 7, taking the ultrasonic wave with a frequency range of 1 MHz to 8 MHz as the low-frequency ultrasonic wave as an example, by changing the thickness of the package 12, the maximum sound pressure of the high-frequency ultrasonic wave basically remains unchanged, while for the low-frequency ultrasonic wave, the frequency value and sound pressure value of the low-frequency ultrasonic wave are effectively adjusted, that is, by adjusting the thickness of the package 12, the adjustment design of the frequency value of the low-frequency ultrasonic wave can be more effectively realized to meet the frequency design requirements of the low-frequency ultrasonic wave.

[0121] For example, the thickness of the package 12 may vary within a range of 50 μm to 150 μm (inclusive of the boundary values), and the frequency of the low-frequency ultrasonic wave may vary within a range of 8 MHz to 2 MHz (inclusive of the boundary values).

[0122] For example, referring to FIG7 , curve S1: E140+Si120(3+1), curve S2: E+Si120(3+1), and curve S3: E100+Si120(3+1) in FIG7 are sound pressure curves when the thickness of the package 12 is 140 μm, 120 μm, and 100 μm, respectively. As the thickness of the package 12 increases from 100 μm to 140 μm, the frequency value of the low-frequency ultrasonic wave changes from 8.6 MHz to 6.5 MHz.

[0123] The following examples illustrate the assembly applications of ultrasonic sensors in electronic equipment, vehicles, and other equipment.

[0124] FIG8 is a schematic diagram of an assembly cross-sectional structure of the ultrasonic sensor and the device cover in FIG3 .

[0125] When the ultrasonic sensor 100 is used in a device, illustratively, the ultrasonic sensor 100 may be bonded and fixed to the cover plate 200 . As shown in FIG. 8 , the ultrasonic sensor 100 may be fixed to the cover plate 200 via a second adhesive layer 300 .

[0126] The second adhesive layer 300 may be an acoustic / mechanical coupling layer, the second adhesive layer 300 may be a homogeneous film layer formed by an adhesive material, or the second adhesive layer 300 may be a composite film layer formed by stacking multiple layers.

[0127] In some examples, the ultrasonic sensor 100 can be fixed to the cover plate 200 by a face-on bonding method. As shown in FIG8 , the side of the protective layer 25 of the ultrasonic sensor 100 facing away from the chip 10 can be bonded to the first surface of the cover plate 200 via a second adhesive layer 300 .

[0128] FIG9 is a schematic diagram of loading the ultrasonic sensor excitation signal in FIG8 .

[0129] As shown in FIG9 , an excitation signal Tx can be applied through the electrode layer 23 of the ultrasonic sensor 100, and the second pixel electrode 211 can be grounded or in a set state. Under voltage excitation, the piezoelectric layer 22 generates ultrasonic waves, which propagate along the stacking direction toward the cover plate 200 and toward the chip 10, respectively. This causes the layers above and below the piezoelectric layer 22 (such as the chip substrate 11, package 12, redistribution expansion layer 21, first adhesive layer 24, and protective layer 25) to resonate. After resonance and superposition, at least two ultrasonic signals of different frequencies are generated. These at least two ultrasonic signals of different frequencies pass through the cover plate 200 and reach a detection location (such as a finger) on the second surface of the cover plate 200.

[0130] FIG10 is a schematic diagram of circuit connections for the ultrasonic sensor 100 in FIG8 to receive echo signals.

[0131] The ultrasonic signals of different frequencies reflected by the detected part are transmitted to the piezoelectric layer 22. When receiving the reflected ultrasonic echo signal, the second pixel electrode 211 can be used to collect the echo signal (the electrical signal converted by the piezoelectric layer 22), and the electrode layer 23 can be grounded or in a set state.

[0132] The piezoelectric layer 22 receives the reflected ultrasonic signals of different frequencies and converts the ultrasonic signals into electrical signals respectively, which are transmitted to the chip 10 through the second pixel electrode 211 to form at least two types of biometric information.

[0133] FIG11 is a schematic diagram of another assembly cross-sectional structure of the ultrasonic sensor and the device cover in FIG3 .

[0134] Alternatively, in some examples, the ultrasonic sensor 100 can also be fixed to the cover plate 200 by reverse pasting. As shown in Figure 11, the fourth surface of the chip 10 of the ultrasonic sensor 100 (the side facing away from the piezoelectric layer group 201) can be bonded and fixed to the first surface of the cover plate 200 through the second adhesive layer 300.

[0135] FIG12 is a schematic diagram of loading the ultrasonic sensor excitation signal in FIG11 .

[0136] Correspondingly, as shown in FIG. 12 , an excitation signal Tx may be applied through the electrode layer 23 of the ultrasonic sensor 100 , and the second pixel electrode 211 may be grounded or in a set state.

[0137] Accordingly, when receiving the reflected ultrasonic signal, the second pixel electrode 211 collects the electrical signal of the piezoelectric layer 22 and transmits it to the chip 10 , and the electrode layer 23 can be grounded or in a set state.

[0138] In the embodiment of the present application, the detection method of the ultrasonic sensor is explained by taking the example that the ultrasonic sensor can emit ultrasonic signals of two frequencies, such as low-frequency ultrasonic signals and high-frequency ultrasonic signals, and the low-frequency ultrasonic signal can be used to realize fingerprint detection, and the high-frequency ultrasonic signal can be used to realize heart rate detection.

[0139] FIG13 is a flow chart of a detection method using the ultrasonic sensor in FIG3 .

[0140] As shown in Figure 13, an ultrasonic sensor can, for example, emit a high-frequency ultrasonic signal and, by receiving the reflected high-frequency ultrasonic signal, obtain a fingerprint image of the finger surface. The measured values ​​in the fingerprint image can be stored in the ultrasonic sensor's memory, or the obtained fingerprint image can be matched with a stored fingerprint image to achieve fingerprint detection and identification. For example, if the detected fingerprint images match, a currently disabled function of the device can be activated.

[0141] The ultrasonic sensor emits a low-frequency ultrasonic signal. By receiving the reflected low-frequency ultrasonic signal, an image of the subcutaneous tissue can be obtained. The subcutaneous tissue image can be formed by the echo reflected from one or more tissues deep within the epidermis of the finger. For example, the ultrasonic sensor can be repeatedly operated to collect and capture subcutaneous tissue images over a period of time to obtain multiple sets of images. Each set of images can include one or more subcutaneous tissue images. The multiple sets of images can be stored in the memory of the ultrasonic sensor. Based on the multiple sets of images, it can be determined whether there is a signal with a rate oscillation within the normal range of the subcutaneous tissue (such as the heart, lungs, etc.). Based on the rate oscillation signal, information such as the heart rate (or respiratory rate) can be identified and tracked.

[0142] It should be noted that the detection of multiple biometric features by the ultrasonic sensor may be performed simultaneously, or may be performed in a sequential order of detection and identification.

[0143] For example, in some examples, the high-frequency ultrasonic signal emitted by the ultrasonic sensor can be used as the primary frequency signal, and the low-frequency ultrasonic signal can be used as the auxiliary frequency signal. The ultrasonic sensor is primarily used to detect and identify fingerprints, and the detection of heart rate and other functions can be implemented as a function after fingerprint detection and authentication. For example, only when the detected fingerprint image matches can the low-frequency ultrasonic signal emitted by the ultrasonic sensor be used to identify and track heart rate and other functions.

[0144] Alternatively, in some examples, the high-frequency ultrasonic signals and low-frequency ultrasonic signals emitted by the ultrasonic sensor can detect heart rate, etc. while detecting a fingerprint image.

[0145] Of course, in some examples, fingerprint detection and heart rate detection can also be implemented independently. For example, when fingerprint detection is needed, the detection is achieved through the high-frequency ultrasonic signal emitted by the ultrasonic sensor. When heart rate detection is needed, the detection is achieved through the low-frequency ultrasonic signal emitted by the ultrasonic sensor.

[0146] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances. The terms "first", "second", "third", "fourth", etc. (if any) are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them. Although the embodiments of the present application have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An ultrasonic sensor, characterized in that: include: A chip, the chip comprising a chip substrate and a package wrapped around the periphery of the chip substrate, the package and the chip substrate being made of different molding materials; A piezoelectric resonance unit, wherein the piezoelectric resonance unit comprises a piezoelectric layer group and a protective layer group, wherein the piezoelectric layer group and the protective layer group are sequentially stacked on one surface of the chip; The piezoelectric layer group is configured to generate ultrasonic waves, and the ultrasonic waves are superimposed through the resonance of the chip, the piezoelectric layer group, and the protective layer group to form at least two ultrasonic signals of different frequencies. The piezoelectric layer group is also configured to receive reflected ultrasonic signals of different frequencies, and convert them into electrical signals respectively and transmit them to the chip. The chip is configured to obtain at least two types of biometric information according to the electrical signals. The at least two ultrasonic signals of different frequencies include an ultrasonic wave of a preset frequency, each layer in the piezoelectric resonance unit has a corresponding first preset thickness, the chip substrate and the package have a second preset thickness and a third preset thickness, respectively, and the first preset thickness, the second preset thickness and the third preset thickness are set according to the frequency value of the ultrasonic wave of the preset frequency.

2. The ultrasonic sensor according to claim 1, characterized in that: The piezoelectric resonance unit satisfies the condition: 0.1≤∑(h i / λ i )≤0.4, where h i is the first preset thickness of each layer in the piezoelectric resonance unit, λ i is the wavelength of the preset frequency ultrasonic wave in each layer of the piezoelectric resonance unit.

3. The ultrasonic sensor according to claim 2, characterized in that: The piezoelectric resonance unit satisfies the conditional formula: ∑(h i / λ i )=1 / 4.

4. The ultrasonic sensor according to claim 2 or 3, characterized in that: The ultrasonic sensor satisfies the condition: 0.3≤∑(h i / λ i )+(h a / λ a )≤0.7, where h a is the second preset thickness or the third preset thickness, λ a The preset frequency ultrasonic wave corresponds to a wavelength in the chip substrate or the package.

5. The ultrasonic sensor according to claim 4, characterized in that: The ultrasonic sensor satisfies the conditional formula: ∑(h i / λ i )+(h a / λ a )=1 / 2.

6. The ultrasonic sensor according to any one of claims 1 to 5, characterized in that: The second preset thickness is equal to the third preset thickness, the chip substrate and the package form a chip base with consistent thickness, and the thickness of the chip base is negatively correlated with the frequency value of the ultrasonic wave of the preset frequency.

7. The ultrasonic sensor according to any one of claims 1 to 5, characterized in that: The third preset thickness is negatively correlated with the frequency value of the ultrasonic wave of the preset frequency.

8. The ultrasonic sensor according to any one of claims 1 to 7, characterized in that: The protective layer group includes a first adhesive layer and a protective layer, and the protective layer is arranged on the piezoelectric layer group through the first adhesive layer.

9. The ultrasonic sensor according to any one of claims 1 to 8, characterized in that: The chip further comprises a plurality of first pixel electrodes, wherein the plurality of first pixel electrode arrays are distributed on one surface of the chip substrate; The piezoelectric layer group includes a redistribution expansion layer, a piezoelectric layer and an electrode layer stacked in sequence, the electrode layer is used to apply voltage excitation to the piezoelectric layer, the piezoelectric layer is used to emit ultrasonic waves under the voltage excitation, and the piezoelectric layer is also used to receive reflected ultrasonic signals and convert the ultrasonic signals into electrical signals; The redistribution expansion layer covers multiple first pixel electrodes, and multiple array-distributed second pixel electrodes are arranged on the side of the redistribution expansion layer facing away from the chip. The multiple second pixel electrodes are correspondingly connected to the multiple first pixel electrodes, and the piezoelectric layer covers the multiple second pixel electrodes.

10. The ultrasonic sensor according to claim 6, characterized in that: The preset frequency ultrasonic wave includes one of a high frequency ultrasonic wave or a low frequency ultrasonic wave, and the frequency value of the high frequency ultrasonic wave is higher than the frequency value of the low frequency ultrasonic wave; The thickness of the chip substrate is 200 μm to 50 μm, and the frequency value of the high-frequency ultrasonic wave is 8 Mhz to 20 Mhz, 15 Mhz to 25 Mhz.

11. The ultrasonic sensor according to claim 7, characterized in that: The preset frequency ultrasonic wave includes one of a high frequency ultrasonic wave or a low frequency ultrasonic wave, and the frequency value of the high frequency ultrasonic wave is higher than the frequency value of the low frequency ultrasonic wave; The thickness of the package is 50 μm to 150 μm, and the frequency value of the low-frequency ultrasonic wave is 8 Mhz to 2 Mhz.

12. The ultrasonic sensor according to any one of claims 1 to 11, characterized in that: The at least two biometric characteristic signals include at least one of a fingerprint signal, a heart rate signal, a blood oxygen signal, a blood pressure signal, and a respiratory rate signal.

13. A sensor module, characterized in that: It comprises a control chip and the ultrasonic sensor according to any one of claims 1 to 12, wherein the ultrasonic sensor is electrically connected to the control chip.

14. An electronic device, characterized in that: It comprises a cover plate and the ultrasonic sensor according to any one of claims 1 to 12, wherein the ultrasonic sensor is fixed to one side of the cover plate; The chip of the ultrasonic sensor is located at an end of the ultrasonic sensor away from the cover plate, or the chip of the ultrasonic sensor is connected to the cover plate.

15. The electronic device according to claim 14, characterized in that: It also includes a second adhesive layer, and the ultrasonic sensor is fixed to the cover plate through the second adhesive layer.

16. A vehicle, characterized in that: It comprises a cover plate and the ultrasonic sensor according to any one of claims 1 to 12, wherein the ultrasonic sensor is fixed to one side of the cover plate; The chip of the ultrasonic sensor is located at an end of the ultrasonic sensor away from the cover plate, or the chip of the ultrasonic sensor is connected to the cover plate.

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