CN108235748B

CN108235748B - Piezoresistive sensor, pressure detection device, and electronic apparatus

Info

Publication number: CN108235748B
Application number: CN201780002813.6A
Authority: CN
Inventors: 文达飞; 冉锐; 陈淡生
Original assignee: Shenzhen Huiding Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2017-02-10
Filing date: 2017-02-10
Publication date: 2020-01-03
Anticipated expiration: 2037-02-10
Also published as: CN108235748A; WO2018145304A1

Abstract

A piezoresistive sensor, a pressure detection device and electronic equipment belong to the field of electronic technical equipment. The piezoresistive sensor comprises a substrate (12) and a half-bridge piezoresistive sensing unit; the half-bridge piezoresistive sensing unit comprises two bridge arms (6, 7), and the two bridge arms (6, 7) are connected in series; a signal acquisition end (IN) is led out from the connecting ends of the two bridge arms (6, 7); excitation signal applying ends are respectively led out from the open ends of the two bridge arms (6, 7); each bridge arm (6, 7) comprises at least one resistance unit (101, 102, 103, 104), the resistance units (101, 102, 103, 104) are positioned on the substrate (12), and the two bridge arms (6, 7) comprise the same number of resistance units (101, 102, 103, 104). When the piezoresistive sensor realizes the pressure detection function, the temperature drift can be inhibited, the signal quantity is increased, the requirement on the internal space of the whole electronic equipment is low, and the piezoresistive sensor is easy to popularize and use.

Description

Piezoresistive sensor, pressure detection device, and electronic apparatus

Technical Field

The invention relates to the field of electronic technical equipment, in particular to a piezoresistive sensor, a pressure detection device and electronic equipment.

Background

In the prior art, a pressure detection scheme of an electronic device is mainly based on a capacitive sensor for detection. The principle of this solution is to press the cover plate 2 with a finger 1, as shown in fig. 1. The pressure exerted by the finger 1 is conducted through the cover plate 2 to the first plate 41 of the capacitive sensor 4. The first plate 41 is deformed by a force, so that the distance between the first plate 41 and the second plate 42 is changed. Accordingly, the capacitance value of the capacitive sensor 4 changes, and thus the pressure can be detected according to the above-described principle.

However, in the process of implementing the present invention, the inventors found that the following technical problems exist in the prior art: the pressure detection by the capacitance sensor requires that the first plate 41 and the second plate 42 of the capacitance sensor 4 be arranged opposite to each other. The first plate 41 needs to be adhered to the cover plate 2 by the adhesive 3. The second plate 42 is adhered to the carrier plate 5 by the adhesive 3. However, the design method has a high requirement on the internal space of the whole electronic device, and has high requirements on the matching, tolerance control, assembly, factory test and the like of the first pole plate 41, the second pole plate 42, the cover plate 2 and the carrier plate 5.

Disclosure of Invention

Embodiments of the present invention provide a piezoresistive sensor, a pressure detection device, and an electronic device, so that when the piezoresistive sensor implements a pressure detection function, temperature drift can be suppressed, a signal amount is increased, and requirements for an internal space of the whole electronic device are low, which is easy to popularize and use.

In order to solve the above technical problem, an embodiment of the present invention provides a piezoresistive sensor, including a substrate and a half-bridge piezoresistive sensing unit; the half-bridge type piezoresistive sensing unit comprises two bridge arms which are connected in series; wherein, the connecting ends of the two bridge arms lead out signal acquisition ends; excitation signal applying ends are respectively led out from the open ends of the two bridge arms; each bridge arm comprises at least one resistance unit, the resistance units are located on the substrate, and the number of the resistance units of the two bridge arms is the same.

The embodiment of the invention also provides a pressure detection device, which comprises the piezoresistive sensor and a processor, wherein the piezoresistive sensor is used for receiving pressure; and the processor is used for processing the signals output by the piezoresistive sensor to obtain pressure information of the pressure.

The embodiment of the invention also provides electronic equipment which comprises the pressure detection device.

Compared with the prior art, the piezoresistive sensor comprises the substrate and the half-bridge type piezoresistive sensing unit, so that when the piezoresistive sensor achieves a pressure detection function, temperature drift can be inhibited, and the signal quantity can be increased. And the piezoresistive sensor is used for detecting pressure, and the piezoresistive sensor is arranged on a certain stress surface to be detected. The piezoresistive sensor is deformed by stress, so that the resistance value of the piezoresistive sensor is correspondingly changed. The structural design of the capacitive sensor plate can be avoided. The requirement on the internal space of the whole electronic equipment is low, and the electronic equipment is easy to popularize and use. And the assembling mode of assembling the piezoresistive sensor to the electronic equipment is simple, and the piezoresistive sensor is favorably fused to each part of the electronic equipment to realize various abundant applications.

In addition, the number of the half-bridge type piezoresistive sensing units is two, namely a first half-bridge type piezoresistive sensing unit and a second half-bridge type piezoresistive sensing unit; and the excitation signal applying end of the first half-bridge type piezoresistive sensing unit is electrically connected with the excitation signal applying end of the second half-bridge type piezoresistive sensing unit.

In addition, the first half-bridge piezoresistive sensing unit and the second half-bridge piezoresistive sensing unit both comprise two resistance units, two resistance units are distributed on one surface of the substrate, and two resistance units are distributed on the other surface of the substrate.

In addition, the number of the substrates is at least two; each substrate is provided with a resistance unit.

In addition, the resistance unit includes a resistance layer and two lead terminals; the two lead terminals and the resistive layer are attached to the substrate by: coating the two lead terminals on the substrate at intervals, coating the resistance layer on the substrate, and enabling the resistance layer to be located between the two lead terminals, wherein two ends of the resistance layer respectively extend to the two lead terminals, and coating an insulating layer above the resistance layer and the lead terminals so that the insulating layer covers the resistance layer and the lead terminals; or coating the resistance layer on the substrate, coating the two lead terminals on the substrate respectively and locating at two ends of the resistance layer, wherein the two lead terminals extend onto the resistance layer respectively, and coating an insulation layer above the resistance layer and the lead terminals so that the insulation layer covers the resistance layer and the lead terminals; or, will the resistive layer with two lead terminal respectively coat in on the base plate, just two lead terminal are located the both ends of resistive layer, wherein, two lead terminal are the stereoplasm lead terminal the resistive layer with the top coating silver thick liquid that the lead terminal is adjacent at resistive layer, lead terminal and silver thick liquid top coating insulating layer to make insulating layer cover resistive layer, lead terminal and silver thick liquid.

In addition, the resistive layer may have a rectangular, serpentine or serpentine shape.

In addition, the pressure detection device also comprises a cover plate; the cover plate covers the piezoresistive sensor, and the piezoresistive sensor is attached to the cover plate through adhesive glue; the cover plate is used for receiving pressure and conducting the pressure to the piezoresistive sensor.

In addition, the electronic device includes side key assemblies, each including a piezoresistive sensor.

In addition, the number of the side key assemblies is at least two, a protruding buckle is arranged between every two adjacent piezoresistive sensors, and the height of the protruding buckle is larger than that of the piezoresistive sensors.

In addition, the electronic equipment comprises a fingerprint identification key assembly with a pressure detection function, the fingerprint identification key assembly comprises a fingerprint module and two piezoresistive sensors; the fingerprint module set up in the apron is inboard, and two piezoresistive sensor is located respectively the both sides of fingerprint module.

In addition, the electronic device comprises a display component with a touch function, and the display component further comprises a display screen and a touch sensor; the display screen is positioned between the cover plate and the piezoresistive sensor; the touch sensor is positioned between the cover plate and the display screen, or the touch sensor is integrated in the display screen, wherein the piezoresistive sensor is made of a transparent material; or the touch sensor is positioned between the cover plate and the piezoresistive sensor; the display screen is fixed on the piezoresistive sensor, wherein the piezoresistive sensor is made of transparent materials.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

FIG. 1 is a schematic diagram of a pressure detection scheme of an electronic device in the prior art;

FIG. 2 is a schematic diagram of a half-bridge topology of a piezoresistive sensor according to a first embodiment;

FIG. 3 is a schematic circuit diagram of a half bridge application of a piezoresistive sensor according to a first embodiment;

FIG. 4 is a schematic diagram of a full-bridge topology of a piezoresistive sensor according to a first embodiment;

FIG. 5 is a schematic diagram of the equivalent resistance of a full bridge topology according to the first embodiment;

fig. 6 is a circuit diagram of a full bridge application principle of the piezoresistive sensor according to the first embodiment;

FIG. 7 is a diagram illustrating a first layout of a resistor unit on a substrate according to an embodiment;

FIG. 8 is a diagram illustrating a second layout of resistor units on a substrate according to one embodiment;

FIG. 9 is a diagram illustrating a third layout of resistor units on a substrate according to an embodiment;

FIG. 10 is a schematic diagram of a full bridge topology of a piezoresistive sensor comprising two resistive elements per leg according to the first embodiment;

FIG. 11 is a schematic diagram of a first layout in which resistor units are dispersedly disposed on both sides of a substrate according to an embodiment;

FIG. 12 is a diagram illustrating a second layout in which resistor units are dispersedly disposed on both sides of a substrate according to an embodiment;

FIG. 13 is a schematic diagram of a third layout of the resistor units distributed on both sides of the substrate according to one embodiment;

FIG. 14 is a diagram illustrating a second layout of the resistor units distributed on two substrates according to one embodiment;

FIG. 15 is a diagram illustrating a third layout of the resistor units dispersedly disposed on two substrates according to one embodiment;

FIG. 16 is a schematic diagram of a rectangular piezoresistive sensor according to an embodiment;

FIG. 17 is a schematic diagram of a piezoresistive sensor according to a first embodiment of the serpentine resistive layer;

FIG. 18 is a schematic diagram of a piezoresistive sensor with a meander resistive layer according to a first embodiment;

FIG. 19 is a cross-sectional view of a piezoresistive sensor formed by a first manufacturing process in one embodiment;

FIG. 20 is a cross-sectional view of a piezoresistive sensor formed by a second manufacturing process in one embodiment;

FIG. 21 is a cross-sectional view of a piezoresistive sensor formed by a third manufacturing process in one embodiment;

fig. 22 is a sectional view of a keyboard according to a third embodiment;

FIG. 23 is a schematic structural diagram of a mouse according to a third embodiment;

FIG. 24 is a schematic view of a stack-up structure of virtual keys according to a third embodiment;

fig. 25 is a sectional view of a virtual key according to the third embodiment;

FIG. 26 is a diagram illustrating a stress analysis of a virtual key according to the third embodiment;

fig. 27 is a schematic structural view of a side key assembly having a key function according to a third embodiment;

fig. 28 is a schematic structural view of a side key assembly having two key functions according to a third embodiment;

FIG. 29 is a cross-sectional view of a fingerprint recognition key assembly having two piezoresistive sensors according to a third embodiment;

FIG. 30 is a sectional view of a fingerprint recognition assembly having a groove on the cover plate according to a third embodiment;

fig. 31 is a cross-sectional view of a fingerprint recognition key assembly having grooves on both the upper and lower surfaces of a cover plate according to a third embodiment;

FIG. 32 is a cross-sectional view of a fingerprint recognition key assembly with a cover plate having through-holes according to a third embodiment;

FIG. 33 is a cross-sectional view of a fingerprint recognition key assembly having a piezoresistive sensor according to a third embodiment;

FIG. 34 is a cross-sectional view of a fingerprint recognition key assembly with two solder points according to a third embodiment;

FIG. 35 is a cross-sectional view of a fingerprint recognition key assembly with one solder joint according to a third embodiment;

FIG. 36 is a cross-sectional view of a display assembly with a touch sensor positioned between a cover and a display screen according to a third embodiment;

fig. 37 is a sectional view of a display module in which a touch sensor is integrated inside a display screen according to a third embodiment;

FIG. 38 is a cross-sectional view of a display assembly with a touch sensor positioned between a cover plate and a piezoresistive sensor according to a third embodiment;

fig. 39 is a sectional view of an electronic apparatus according to a third embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present application in various embodiments of the present invention. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.

A first embodiment of the present invention relates to a piezoresistive sensor. As shown in fig. 2, the piezoresistive sensor includes a substrate and a half-bridge piezoresistive sensing unit. When the half-bridge type piezoresistive sensing unit realizes a pressure detection function, temperature drift can be inhibited, and the signal quantity can be increased. The half-bridge type piezoresistive sensing unit comprises two bridge arms which are connected in series; wherein, the connecting ends of the two bridge arms lead out signal acquisition ends; excitation signal applying ends are respectively led out from the open ends of the two bridge arms; each bridge arm comprises at least one resistance unit, the resistance units are located on the substrate, and the number of the resistance units of the two bridge arms is the same.

Note that the excitation signal application terminal is used to apply a high level or a low level. Specifically, as shown IN fig. 2, the signal acquisition terminal IN is led out from the connection end of the two bridge arms. The two legs are a first leg 6 and a second leg 7, respectively. The excitation signal application terminal led out from the open terminal of first arm 6 is used for applying a high level (that is, voltage VDD can be applied to the open terminal of first arm 6). The excitation signal application terminal led out from the open terminal of second arm 7 is used for applying a low level (i.e., the open terminal of the second arm may be grounded GND). The substrate may be, but is not limited to, a printed circuit board, PCB, board. The material of the substrate may be, but is not limited to: polyimide PI material, polyester resin PET material, glass or polymethyl methacrylate PMMA material. As shown in fig. 3, it is worth mentioning that the piezoresistive sensor has a half-bridge topology unit structure. To distinguish from a full bridge piezoresistive sensor. Piezoresistive sensors may be referred to as half-bridge piezoresistive sensors. The half-bridge piezoresistive sensor 10 is connected to the detection chip 8, and the detection chip 8 is connected to the main control chip 9. Specifically, the signal acquisition terminal IN of the half-bridge piezoresistive sensor 10 is connected to the preamplifier unit 803 through the multiplexing switch unit 801, and is connected to the processor unit 805 through the analog-to-digital conversion circuit unit 804, and the processor unit 805 is connected to the main control chip 9. An excitation signal applying terminal of the half-bridge piezoresistive sensor 10 is connected to the excitation signal circuit unit 802, and the excitation signal circuit unit 802 applies a voltage to the half-bridge piezoresistive sensor 10. The excitation signal circuit unit 802 is coupled to the processor unit 805. When pressure is applied to the piezoresistive sensor, the resistance of the first bridge arm 6 and the resistance of the second bridge arm 7 change, and the voltage division ratio of the resistance of the first bridge arm 6 and the resistance of the second bridge arm 7 is influenced, so that the signal size of the signal acquisition end IN is influenced. The detection chip 8 calculates the magnitude of the pressure by detecting the signal change of the signal acquisition terminal IN. When temperature influences exist, resistance value drift generated by the resistance of the first bridge arm 6 and the resistance of the second bridge arm 7 due to the temperature influences is close, and the voltage division ratio of the IN point basically keeps unchanged, so that the influence of the temperature drift on signal change of the IN signal point is limited, and the influence of the temperature drift can be restrained.

In addition, in order to further inhibit temperature drift, two half-bridge type piezoresistive sensing units are provided, namely a first half-bridge type piezoresistive sensing unit and a second half-bridge type piezoresistive sensing unit; and the excitation signal applying end of the first half-bridge type piezoresistive sensing unit is electrically connected with the excitation signal applying end of the second half-bridge type piezoresistive sensing unit. Specifically, a signal applying terminal of the first half bridge and a signal applying terminal of the second half bridge are connected. The ground terminal of the first half-bridge is connected to the ground terminal of the second half-bridge. The signal acquisition ends of the first half bridge and the second half bridge can be respectively connected to the control circuit. As shown in fig. 4, two half-bridges are spliced together in parallel to form a full-bridge topology. The number of the resistance units is four, and the resistance units are respectively a full-bridge topology structure formed by the first resistance unit 101, the second resistance unit 102, the third resistance unit 103 and the fourth resistance unit 104, and an equivalent circuit of the full-bridge topology structure is shown in fig. 5. The first resistor unit 101, the second resistor unit 102, the third resistor unit 103 and the fourth resistor unit 104 are equivalent to the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4, respectively. The first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are four arms of a full-bridge topology, respectively. The bridge topology unit has four lead terminals. The two opposite lead terminals are respectively connected to the excitation signal VDD and the system ground GND. The other two are signal acquisition ends, which are IN + and IN-, respectively. The two differential signal input ends of IN + and IN-are connected with the detection chip. When pressure is applied to the piezoresistive sensor, the partial pressure ratio of R1 to R2, and the partial pressure ratio of R3 to R4 are affected. The two affect the ratio to be inconsistent and thus affect the differential signal magnitude between IN + and IN-. When the temperature is affected, the resistance value drifts of the two groups of resistors R1 and R2, R3 and R4 caused by the temperature are close. The ratio of the affected partial pressures at the IN + and IN-terminals is substantially unaffected by temperature. Therefore, the influence on the size of the differential signal between the IN + and the IN-is weak, most of signals detected by the chip are due to useful signal changes generated by pressing, and the influence of temperature drift is restrained on a hardware topological structure. It is worth mentioning that the piezoresistive sensor is a full-bridge topological unit structure, and may be called a full-bridge piezoresistive sensor. As shown in fig. 6, in practical applications, the full-bridge piezoresistive sensor 11 is connected to the main control chip 9 through the detection chip 8. Specifically, IN + and IN-of the full-bridge piezoresistive sensor 11 are respectively connected to the preamplifier unit 803 through the multiplexing switch unit 801, and then connected to the processor unit 805 through the analog-to-digital conversion circuit unit 804, and the processor unit 805 is connected to the main control chip 9. The IN + and the IN-are respectively connected with different detection channels, which is beneficial to improving the detection speed. The two detection channels may also be used to perform sampling detection on each full-bridge piezoresistive sensor 11 forming a full-bridge topology unit in a polling manner.

The resistor units may be juxtaposed on the substrate. As shown in fig. 7, the full-bridge piezoresistive sensor is described as an example, and four resistor units may be arranged on the substrate 12. Four resistor units are juxtaposed on the substrate 12. The description will be given taking the direction of the drawing as an example. The first resistance unit, the second resistance unit, the third resistance unit and the fourth resistance unit are arranged from left to right in sequence. The upper terminals of the four resistance units are IN +, IN-and IN-IN sequence from left to right. The lower terminals of the four resistance units are VDD, GND, VDD, and GND in this order from left to right. As shown in fig. 8, the four resistor units may be arranged on the substrate 12 as follows. The upper terminals of the four resistance units are IN-, IN + and IN-IN sequence from left to right. The lower terminals of the four resistance units are VDD, GND, VDD, and GND in this order from left to right. As shown in fig. 9, four resistor units may be arranged on the substrate 12 as follows. The upper terminals of the four resistance units are IN +, IN-, IN + and IN-IN turn from left to right. The lower terminals of the four resistance units are GND, VDD, GND, and the like in this order from left to right. Are not further enumerated here.

As shown in fig. 10, each leg of the full bridge may be composed of two resistor units connected in series. It is worth mentioning that each bridge arm is not limited to being composed of two resistor units connected in series. Three resistance units may be connected in series, four resistance units may be connected in series, and the like, which are not described herein. In addition, in practical applications, each bridge arm may also be formed by connecting two resistance units in parallel under the condition that the resistance values of the resistance units allow.

In this embodiment, the distributed layout of the resistor units on both sides of the substrate helps to improve the detection signal amount under the same deformation effect. Specifically, when the resistor units form a full-bridge topology structure, the resistor units are distributed on two sides of the substrate, so that larger differential signal variation can be obtained under the condition of the same force. Taking fig. 5 as an example, if R1 and R2 are designed at the same layer, when the same deformation is applied to both, the changes generated by them will be relatively similar. This results IN a smaller change IN the division ratio at IN +, and a smaller amount of signal generated, as well as the signal at IN-. When the R1 and the R2 are designed on different layers and the same deformation acts on the two voltage dividing resistors, the difference between the change of R1 and the change of R2 is increased because of different layers. Therefore, the influence on the partial pressure proportion at the IN + position is increased, and the effect of improving the signal variation is achieved. Similarly, the IN-position signal has the effect of increasing the signal variation because R3 and R4 are at different levels. However, if the signals at IN + and IN-are both scaled up equally, the differential signal between IN + and IN-is weak. For example, while R1 and R2 are on different layers, R3 and R4 are on different layers; however, R1 is in the same layer as R3 and R2 is in the same layer as R4. IN this design the signal is seen to be amplified by a single half-bridge, but the differential signal between IN + and IN-between the two half-bridges is not amplified. Therefore, IN the full-bridge topology, a pair of corner bridge arms of R1 and R4 are required to be designed on the same layer, and a pair of bridge arms of R3 and R2 are required to be designed on the same layer, so that the increase of differential signals between IN + and IN-can be realized. If only half-bridge topology is used, the two resistor units are at different levels to increase the check signal. In case of a full bridge topology, the two resistor units within each half bridge should be in different levels and the diagonal resistor units should be in the same level. As shown in fig. 11, a preferred layout is to lay out two resistor units on one surface of the substrate 12. Two resistor units are arranged on the other surface of the substrate 12. Specifically, the following description will be made by taking the direction shown in the drawings as an example: the first resistance unit 101 and the fourth resistance unit 104 are located on the upper surface of the substrate 12. The second resistance unit 102 and the third resistance unit 103 are located on the lower surface of the substrate 12. And the second resistance unit 102 and the third resistance unit 103 are located between the first resistance unit 101 and the fourth resistance unit 104. Alternatively, as shown in fig. 12, the first resistance unit 101 and the fourth resistance unit 104 are located on the upper surface of the substrate 12 and at the right portion of the substrate 12. The second resistance unit 102 and the third resistance unit 103 are located on the lower surface of the substrate 12 and on the left side portion of the substrate 12. Alternatively, the second resistance unit 102 and the third resistance unit 103 (two resistance units of diagonal resistance units) and the first resistance unit 101 and the fourth resistance unit 104 (two resistance units of diagonal resistance units) are sequentially arranged in a direction from one end to the other end of the substrate 12, and as shown in fig. 13, the second resistance unit 102 and the third resistance unit 103 are located on the upper surface of the substrate 12 and on the left side portion of the substrate 12. The first resistance unit 101 and the fourth resistance unit 104 are located on the lower surface of the substrate 12, on the right side portion of the substrate 12, and the like. Are not further enumerated here. It should be noted that, in the present embodiment, the specific position and the specific number of the resistor units on each surface of the substrate 12 are not limited.

In the actual design process, at least two substrates can be designed; the resistance unit is arranged on each substrate. As shown in fig. 14, two substrates are taken as an example for explanation: the two substrates are a first substrate 121 and a second substrate 122, respectively. Two resistor units are disposed on the first substrate 121. Two resistor units are disposed on the second substrate 122. The surface of the first substrate 121 on which the resistor units are disposed is opposite to the surface of the second substrate 122 on which the resistor units are disposed. The first substrate 121 is fixed to the resistor unit on the second substrate 122 by the adhesive 13. As shown in fig. 15, two resistor units are disposed on the first substrate 121. Two resistor units are disposed on the second substrate 122. The surface of the first substrate 121 having the resistance unit is disposed opposite to the surface of the second substrate 122 having the resistance unit. The resistor elements on the first substrate 121 and the resistor elements on the second substrate 122 are fixed to both surfaces of the adhesive 13.

Note that the resistance unit includes a resistance layer and two lead terminals. The resistive layer may be, but is not limited to, carbon or graphene. The material of the two lead terminals can be, but is not limited to, copper or silver paste. It should be noted that the length, width, and thickness of the resistive layer affect the resistance of the pressure-sensitive resistive unit. The piezoresistive sensor which is adaptive to the resistance parameter range of the detection chip circuit can be obtained by adjusting the length, the width and the thickness of the resistance layer. In practical application, the resistance unit 14 is connected to the main control chip 9 through the detection chip 8. The excitation signal unit 802 applies an excitation signal to the resistance unit 14. The resistance unit 14 is sampled by a plurality of processing units inside the detection chip 8. The resistance value change of the resistance unit 14 can be detected in real time, the analog signal change of the resistance value is converted into a digital signal, and the digital signal is subjected to operation processing to obtain a corresponding pressure value and then reported to the main control chip 9. The main control chip 9 receives the pressure information, compares the pressure information with a preset threshold value, and then performs corresponding application command processing. Wherein, the shape of the resistive layer 15 may be, but is not limited to, a rectangle as shown in fig. 16; a serpentine shape as shown in fig. 17; or a clip as shown in figure 18, etc.

One, two lead terminals and a resistive layer are attached to a substrate by the following process:

as shown in fig. 19, two lead terminals 16 are coated on the substrate 12 with a space. A resistive layer 15 is coated on the substrate 12 and is located between two lead terminals 16. Wherein, the two ends of the resistance layer 15 extend to the two lead terminals 16, respectively, which helps to ensure that the lead terminals 16 are sufficiently in contact with the resistance layer 15. An insulating layer 17 is coated over the resistive layer 15 and the lead terminals 16 such that the insulating layer 17 covers the resistive layer 15 and the lead terminals 16. The insulating layer 17 is applied in order to protect the two lead terminals 16 and the resistive layer 15 from oxidation.

Two lead terminals and the resistance layer are attached to the substrate by the following process:

as shown in fig. 20, resistive layer 15 is coated on substrate 12. Two lead terminals 16 are coated on the substrate 12, respectively, and are located at both ends of the resistive layer 15. Wherein the two lead terminals 16 respectively extend onto the resistive layer 15, which helps to ensure that the lead terminals 16 are sufficiently in contact conduction with the resistive layer 15. An insulating layer 17 is coated over the resistive layer 15 and the lead terminals 16 such that the insulating layer 17 covers the resistive layer 15 and the lead terminals 16. The insulating layer 17 is applied in order to protect the two lead terminals 16 and the resistive layer 15 from oxidation.

Three, two lead terminals and a resistive layer are attached to the substrate by the following process:

as shown in fig. 21, the resistive layer 15 and the two lead terminals 16 are coated on the substrate 12, respectively, and the two lead terminals 16 are located at both ends of the resistive layer 15. Both the lead terminals 16 are hard lead terminals. Applying silver paste 18 over the resistive layer 15 and the lead terminal 16 adjacent to each other helps ensure that the lead terminal 16 is in sufficient contact with the resistive layer 15. An insulating layer 17 is coated over the resistive layer 15, the lead terminals 16, and the silver paste 18 such that the insulating layer 17 covers the resistive layer 15, the lead terminals 16, and the silver paste 18. The insulating layer 17 is applied in order to protect the two lead terminals 16 and the resistive layer 15 from oxidation.

From the above, it can be easily found that, in the present embodiment, by the design that the piezoresistive sensor includes the substrate and the half-bridge type piezoresistive sensing unit, when the piezoresistive sensor implements the pressure detection function, the temperature drift can be suppressed, and the signal quantity can be increased. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The requirement on the internal space of the whole electronic equipment is low, and the electronic equipment is easy to popularize and use. The assembling mode of assembling the piezoresistive sensor to the electronic equipment is simple, and the piezoresistive sensor is favorably fused to each part of the electronic equipment to realize various abundant applications.

A second embodiment of the present invention relates to a pressure detection device including the piezoresistive sensor of the first embodiment and a processor; a piezoresistive sensor for receiving pressure; and the processor is used for processing the signals output by the piezoresistive sensor to obtain pressure information of the pressure.

A third embodiment of the present invention relates to an electronic device having a pressure detection function, including the pressure detection apparatus of the second embodiment.

In practical applications, the pressure detecting device further includes a cover plate. The cover plate covers the piezoresistive sensor, and the piezoresistive sensor is attached to the cover plate through the adhesive glue. A cover plate for receiving pressure and conducting pressure to the piezoresistive sensor. The piezoresistive sensor can be attached to the cover plate through adhesive glue.

As shown in fig. 22, the electronic device may include a keypad having a pressure detection function. The cover plate 19 is printed with a number of keyboard characters. Specifically, the surface of the cover plate 19 on which the keyboard characters are not printed is bonded to the piezoresistive sensor by the adhesive 13. Each keyboard character overlies at least one piezoresistive sensor 20.

As shown in fig. 23, the electronic device may be included as a mouse having a pressure detection function. The cover plate 19 is a shell 191 corresponding to the left mouse button and a shell 192 corresponding to the right mouse button.

In practical applications, as shown in fig. 24 and 25, the electronic device may further include a key assembly, and the key assembly has a pressure detection function. The key assembly may be a virtual key. Preferably, the key assembly further includes a touch sensor 21; the touch sensor 21 is located below the cover plate 19. It should be noted that the cover plate may be a display area. Or a key area below the display area. A piezoresistive sensor 22 may be arranged below the virtual key of the electronic device, i.e. the cover plate 19. In practical applications, a display screen 23 is provided between the cover plate 19 and the piezoresistive sensor 22. The function of the key assembly is enriched, and the touch and the pressure can be recognized, so that more applications can be provided for the operation of the key assembly. For example, if the key is pressed by the finger 1 beyond a certain threshold, the corresponding function is set. Such as: a call-out voice assistant, a search function, or a mode switch, etc. A touch sensor 21 is attached below the cover plate 19 by an adhesive 13. Alternatively, a display screen 23 is attached to the lower side of the cover plate 19 by an adhesive 13, and a piezoresistive sensor 22 is fixed to the lower side of the display screen 23. Although only the touch sensor 21 is disposed below the finger-pressing area a, the piezoresistive sensor 22 is not disposed. However, as can be seen from fig. 26, according to the principle of structural mechanical deformation, when the finger 1 presses the edge area of the force-receiving cover plate 19 supported by the fulcrum B, not only the finger-pressing area a is deformed to bend downward. The non-pressed area also deforms. As shown in fig. 28 by the dashed line to solid line position. So that the application design can be made by utilizing the mechanical characteristics. The area of the display screen 23 is also deformed due to the transmission of force when the finger 1 presses the finger pressing area a. Therefore, the piezoresistive sensor 22 in the area of the display 23 can also be used to identify the key pressure.

In addition, the key assembly can also be a side key assembly of the electronic device. As shown in fig. 27, when the key assembly is a side key assembly, the cover plate 19 is a side cover of the electronic device. It is worth mentioning that the assembly of the side edge covers may be of a metallic or non-metallic material, or a mixture of metallic and non-metallic materials. Piezoresistive sensors 22 are attached to the inside of the side edges by adhesive glue 13. The side edge covering can be arranged in a protruding mode, and the finger pressing effect can be guaranteed. As shown in fig. 28, there are at least two piezoresistive sensors 22, and a protruding buckle 24 may be provided between adjacent piezoresistive sensors 22. Specifically, the side keys may be two, such as a power key and a volume key. When the side keys are a power key and a volume key, both the power key and the volume key are arranged with the piezoresistive sensors 22. Both piezoresistive sensors 22 are attached to the inside of the side edge by adhesive 13. Wherein the raised snaps 24 may increase the strength of the cover plate. It is worth mentioning that the two sides of the piezoresistive sensor 22 are both provided with protruding buckles 24. Preferably, the height of the raised snaps 24 is greater than the height of the piezoresistive sensors 22. Specifically, the height of the raised catches 24 is greater than the sum of the thickness of the piezoresistive sensor 22 and the adhesive glue 13. The protruding buckle 24 is equivalent to a plurality of supporting points assumed for the edge covering 19 to form a beam type framework, and like the mechanical framework of fig. 28, the protruding buckle not only can play a role in strengthening the firmness of the edge covering, but also can increase the deformation quantity generated. .

In addition, the key assembly may be a fingerprint recognition key assembly, and as shown in fig. 29, there are two piezoresistive sensors 22. Fingerprint identification button subassembly still includes fingerprint module 25. Fingerprint module 25 is fixed in apron 19 is inboard, and two piezoresistive sensors 22 are located the both sides of fingerprint module 25 respectively. In order to increase the sensitivity of fingerprint recognition, as shown in fig. 30 and 31, a groove 26 may be provided on at least one surface of the cover plate 19. And the groove 26 corresponds to the position of the fingerprint module 25. Specifically, a groove 26 may be provided on the upper surface of the cover plate 19; alternatively, the lower surface of the cover plate 19 may be provided with a groove 26; alternatively, the upper and lower surfaces of the cover plate 19 may be provided with grooves 26; alternatively, as shown in fig. 32, the cover plate 19 is provided with a through hole corresponding to the position of the fingerprint module 25.

In the actual design process, as shown in fig. 33, the two piezoresistive sensors 22 are not limited to be located on two sides of the fingerprint mold 25. For example, the fingerprint module 25 is fixed inside the cover plate 19, and the piezoresistive sensor 22 is fixed at the bottom of the fingerprint module 25 through the adhesive 13. It should be noted that, as shown in fig. 34 and 35, the piezoresistive sensor 22 may be, but is not limited to, fixed to the bottom of the fingerprint module 25 by welding points or glue, foam, etc. 27. In order to protect the piezoresistive sensor 22 from damage, a bump 28 may be provided on the piezoresistive sensor 22 on a side facing away from the solder joint.

The electronic device can further comprise a display assembly with a touch function, the display assembly has a pressure detection function, and the display assembly further comprises a display screen and a touch sensor. The display screen is located between the cover plate and the piezoresistive sensor. The piezoresistive sensor can be designed as a transparent material. Specifically, as shown in fig. 36, the touch sensor 30 is located between the cover 19 and the display screen 29. The touch sensor 30 is fixed to the cover plate 19 by the adhesive 13. The touch sensor 30 is fixed to the display screen 29 by the adhesive 13. As shown in fig. 37, the touch sensor is integrated inside the display screen 29. The cover plate 19 and the display screen 29 are fixed by the adhesive 13. Alternatively, as shown in fig. 38, the display assembly further includes a display screen 29 and a touch sensor 30. The touch sensor 30 is located between the cover plate 19 and the piezoresistive sensor 22. The display screen 29 is fixed to the piezoresistive sensor 22. The cover plate 19 is fixed to the touch sensor 30 by the adhesive 13. The touch sensor 30 is fixed to the piezoresistive sensor 22 by an adhesive 13. The piezoresistive sensor 22 is fixed to the display screen 29 by means of an adhesive glue 13.

It should be understood that this embodiment corresponds to the first embodiment, and that this embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the first embodiment.

As described above, it can be seen that the present embodiment enables the piezoresistive sensor to suppress temperature drift when implementing the pressure detection function. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The requirement on the internal space of the whole electronic equipment is low, and the electronic equipment is easy to popularize and use. The assembling mode of assembling the piezoresistive sensor to the electronic equipment is simple, and the piezoresistive sensor is favorably fused to each part of the electronic equipment to realize various abundant applications.

As a preferred embodiment, the electronic device may further comprise a structural member 31, as shown in fig. 39. The pressure detection means is a display assembly 32 with touch functionality. There is a gap 33 between the display assembly 32 and the structural member 31. Wherein, foam is filled between the gaps 33. It is worth mentioning that the structural member 31 may be, but is not limited to, a middle frame, a rear case, a printed circuit board, or a battery.

Since the first and second embodiments correspond to the present embodiment, the present embodiment can be implemented in cooperation with the first and second embodiments. The related technical details mentioned in the first and second embodiments are still valid in this embodiment, and the technical effects that can be achieved in the first and second embodiments can also be achieved in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can be applied to the first and second embodiments.

As described above, it can be seen that the present embodiment enables the piezoresistive sensor to suppress temperature drift and increase the signal amount when implementing the pressure detection function. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The requirement on the internal space of the whole electronic equipment is low, and the electronic equipment is easy to popularize and use. The assembling mode of assembling the piezoresistive sensor to the electronic equipment is simple, and the piezoresistive sensor is favorably fused to each part of the electronic equipment to realize various abundant applications.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

Claims

1. A piezoresistive sensor is characterized by comprising a substrate and a half-bridge piezoresistive sensing unit;

the half-bridge type piezoresistive sensing unit comprises two bridge arms which are connected in series; the signal acquisition ends are led out from the connecting ends of the two bridge arms; excitation signal applying ends are respectively led out from the open ends of the two bridge arms;

each bridge arm comprises at least one resistance unit, the resistance units are positioned on the substrate, and the number of the resistance units of the two bridge arms is the same;

the number of the half-bridge type piezoresistive sensing units is two, and the two half-bridge type piezoresistive sensing units are respectively a first half-bridge type piezoresistive sensing unit and a second half-bridge type piezoresistive sensing unit; the excitation signal applying end of the first half-bridge type piezoresistive sensing unit is electrically connected with the excitation signal applying end of the second half-bridge type piezoresistive sensing unit;

the first half-bridge piezoresistive sensing unit and the second half-bridge piezoresistive sensing unit respectively comprise two resistance units, and two groups of diagonal resistance units in the first half-bridge piezoresistive sensing unit and the second half-bridge piezoresistive sensing unit are positioned on different surfaces of the substrate; the first half-bridge piezoresistive sensing units and the second half-bridge piezoresistive sensing units form a full-bridge topological structure, and each group of diagonal resistance units comprises two resistance units which are diagonally arranged in the full-bridge topological structure; any two of the resistance units do not spatially overlap in a direction perpendicular to the surface of the substrate.

2. The piezoresistive sensor according to claim 1, wherein there are at least two of said substrates; the two groups of diagonal resistance units are arranged on different surfaces of any one of the substrates, or the two groups of diagonal resistance units are arranged on different surfaces of any one of the substrates through other substrates; each of the substrates is provided with the resistor unit.

3. The piezoresistive sensor according to claim 1, wherein one of the diagonal resistive elements of a group is located between two of the resistive elements of another group.

4. The piezoresistive sensor according to claim 1, wherein two of the resistive elements of one group of the diagonal resistive elements and two of the resistive elements of the other group of the diagonal resistive elements are arranged in sequence in a direction from one end of the substrate to the other end.

5. The piezoresistive sensor according to claim 1, wherein said one resistive element comprises a resistive layer and two lead terminals;

the two lead terminals and the resistive layer are attached to the substrate by: coating the two lead terminals on the substrate at intervals, and coating the resistance layer on the substrate, wherein the resistance layer is positioned between the two lead terminals; wherein, two ends of the resistance layer extend to the two lead terminals respectively, and an insulating layer is coated above the resistance layer and the lead terminals so that the insulating layer covers the resistance layer and the lead terminals;

or coating the resistance layer on the substrate, and respectively coating the two lead terminals on the substrate and at two ends of the resistance layer; wherein the two lead terminals extend onto the resistive layer, respectively, and an insulating layer is coated over the resistive layer and the lead terminals such that the insulating layer covers the resistive layer and the lead terminals;

or the resistance layer and the two lead terminals are respectively coated on the substrate, and the two lead terminals are positioned at two ends of the resistance layer; wherein, two lead terminals are the stereoplasm lead terminal the resistive layer with the top coating silver thick liquid that the lead terminal is adjacent the resistive layer lead terminal and silver thick liquid top coating insulating layer, so that the insulating layer covers the resistive layer lead terminal and silver thick liquid.

6. The piezoresistive sensor according to claim 5, wherein the resistive layer has a rectangular, serpentine or meander shape.

7. A pressure detection device comprising the piezoresistive sensor according to any of claims 1 to 6 and a processor;

the piezoresistive sensor is used for receiving pressure;

and the processor is used for processing the signal output by the piezoresistive sensor to obtain the pressure information of the pressure.

8. An electronic device having a pressure detection function, comprising: the pressure detection apparatus of claim 7.

9. The electronic device of claim 8, further comprising a cover plate;

the cover plate covers the piezoresistive sensor, and the piezoresistive sensor is attached to the cover plate through adhesive glue;

the cover plate is used for receiving pressure and conducting the pressure to the piezoresistive sensor.

10. The electronic device of claim 8, wherein the electronic device comprises side key assemblies, each side key assembly comprising a piezoresistive sensor.

11. The electronic device of claim 10, wherein there are at least two side key assemblies, and a raised snap is disposed between adjacent piezoresistive sensors, and the height of the raised snap is greater than the height of the piezoresistive sensors.

12. The electronic device of claim 9, wherein the electronic device comprises a fingerprint key assembly with pressure detection function, the fingerprint key assembly comprising a fingerprint module and a piezoresistive sensor; the fingerprint module set up in the apron is inboard, just piezoresistive sensor is located the bottom of fingerprint module.

13. The electronic device of claim 12, wherein at least one side of the cover plate is provided with a groove corresponding to a position of the fingerprint module;

or,

the apron is equipped with the through-hole, just the through-hole corresponds to the position of fingerprint module.

14. The electronic device of claim 9, wherein the electronic device comprises a display component with touch functionality, the display component further comprising a display screen and a touch sensor; the display screen is positioned between the cover plate and the piezoresistive sensor; the touch sensor is positioned between the cover plate and the display screen, or the touch sensor is integrated in the display screen;

or the touch sensor is positioned between the cover plate and the piezoresistive sensor; the display screen is fixed on the piezoresistive sensor.