WO2018145304A1

WO2018145304A1 - Piezoresistive sensor, pressure measurement device and electronic device

Info

Publication number: WO2018145304A1
Application number: PCT/CN2017/073254
Authority: WO
Inventors: 文达飞; 冉锐; 陈淡生
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2017-02-10
Filing date: 2017-02-10
Publication date: 2018-08-16
Also published as: CN108235748B; CN108235748A

Abstract

A piezoresistive sensor, a pressure measurement device and an electronic device, relating to the technical field of electronic devices. The piezoresistive sensor comprises substrates (12), and half-bridge type piezoresistive sensing units; each of the half-bridge type piezoresistive sensing unit comprises two bridge arms (6, 7), the two bridge arms being connected in series; signal acquisition ends (IN) are led out from the connecting ends of the two bridge arms (6, 7); excitation signal applying ends are led out from the opening ends of the two bridge arms (6, 7) respectively; each of the bridge arms (6, 7) comprises at least one resistor unit (101, 102, 103, 104); the resistor units (101, 102, 103, 104) are disposed on the substrates (12); and each of the bridge arms (6, 7) comprises the same number of the resistor units (101, 102, 103, 104). The piezoresistive sensor can inhibit temperature drift and increase semaphore while implementing the pressure measurement function; and the piezoresistive sensor has low requirement for the internal space of the entire electronic device and can be easily popularized.

Description

Piezoresistive sensor, pressure detecting device, electronic device

Technical field

The present invention relates to the field of electronic technology devices, and in particular, to a piezoresistive sensor, a pressure detecting device, and an electronic device.

Background technique

In the prior art, the pressure detection scheme of the electronic device is mainly based on the detection of the capacitive sensor. As shown in Fig. 1, the principle of this scheme is to press the cover 2 with the finger 1. The pressure applied by the finger 1 is conducted through the cover 2 to the first plate 41 of the capacitive sensor 4. The first plate 41 is deformed by force to change the spacing between the first plate 41 and the second plate 42. Thereby, the magnitude of the capacitance value of the capacitance sensor 4 is changed, so that the pressure can be detected according to the above principle.

However, in the process of implementing the present invention, the inventors have found that the following technical problems exist in the prior art: the detection of the pressure based on the capacitive sensor requires that the first plate 41 and the second plate 42 of the capacitive sensor 4 are disposed opposite each other. The first plate 41 needs to be bonded to the cover 2 by the adhesive 3 . The second plate 42 is bonded to the carrier plate 5 by an adhesive 3. However, this design method requires relatively high internal space of the entire electronic device, and the matching, tolerance control, assembly, and factory test of the first plate 41, the second plate 42, the cover plate 2, and the carrier plate 5 are all Have higher requirements.

Summary of the invention

An object of the embodiments of the present invention is to provide a piezoresistive sensor, a pressure detecting device, and an electronic device, so that the piezoresistive sensor can suppress temperature drift, increase signal amount, and internal space of the entire electronic device when implementing the pressure detecting function. The requirements are relatively low and easy to promote.

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 piezoresistive sensing unit includes two bridge arms, and the two bridge arms are connected in series Wherein the connection ends of the two bridge arms lead to the signal acquisition end; the open ends of the two bridge arms respectively lead to the excitation signal application ends; each of the bridge arms includes at least one resistance unit, and the resistance unit is located on the substrate, wherein the two bridges The arm includes the same number of resistor units.

The embodiment of the invention further provides a pressure detecting device, comprising the above-mentioned piezoresistive sensor and processor, a piezoresistive sensor for receiving pressure, and a processor for processing a signal output by the piezoresistive sensor to obtain Pressure information of the pressure.

Embodiments of the present invention also provide an electronic device including the above pressure detecting device.

Compared with the prior art, the piezoresistive sensor includes a substrate and a half-bridge piezoresistive sensing unit, so that the piezoresistive sensor can suppress temperature drift when implementing the pressure detecting function, and can also Increase the semaphore. Moreover, using a piezoresistive sensor to achieve pressure detection, it is only necessary to arrange the piezoresistive sensor on a force surface to be tested. The piezoresistive sensor is deformed by force, so that the resistance of the piezoresistive sensor changes accordingly. The structural design of the capacitive sensor plate can be avoided. The internal space requirements of the entire electronic device are relatively low and easy to promote. Moreover, the assembly of the piezoresistive sensor to the electronic device is relatively simple, and the piezoelectric resistance sensor is integrated into various components of the electronic device to realize various rich applications.

In addition, the two bridge type piezoresistive sensing units are respectively a first half bridge piezoresistive sensing unit and a second half bridge piezoresistive sensing unit; the first half bridge piezoresistive sensing unit The excitation signal application end is electrically connected to the excitation signal application end of the second half bridge piezoresistive sensing unit.

In addition, the first half bridge piezoresistive sensing unit and the second half bridge piezoresistive sensing unit each include two resistor units, one of which is disposed on one side of the substrate, and two resistor units are disposed on the other side of the substrate.

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

In addition, the resistance unit includes a resistance layer and two lead terminals; two lead terminals and the resistor The layer is attached to the substrate by a process of: coating the two lead terminals on the substrate, coating the resistive layer on the substrate, and the resistive layer is located on the substrate Between the lead terminals, wherein the two ends of the resistive layer extend to the two lead terminals respectively, and an insulating layer is coated on the resistive layer and the lead terminal to cover the resistive layer and the lead a terminal; or, the resistive layer is coated on the substrate, the two lead terminals are respectively coated on the substrate, and are located at two ends of the resistive layer, wherein the two leads Extending the terminal to the resistance layer, respectively, coating an insulating layer over the resistance layer and the lead terminal to cover the resistance layer and the lead terminal; or, the resistance layer and the two leads The terminals are respectively coated on the substrate, and the two lead terminals are located at two ends of the resistance layer, wherein the two lead terminals are hard lead terminals, and the resistance layer and the lead are Silver coated on the top adjacent to the terminal In the resistive layer, and the lead terminal insulating layer coated over the silver paste, so that the insulating layer covering the resistance layer, and the lead terminal silver paste.

In addition, the shape of the resistance layer is rectangular, serpentine or retro.

In addition, 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 by an adhesive; the cover plate is used for receiving pressure and The pressure is conducted to the piezoresistive sensor.

Additionally, the electronic device includes side key assemblies, each of which includes a piezoresistive sensor.

In addition, the side key assemblies are at least two, and the adjacent piezoresistive sensors are provided with a protruding buckle, and the height of the protruding buckle is greater than the height of the piezoresistive sensor.

In addition, the electronic device includes a fingerprint recognition button component having a pressure detection function, the fingerprint recognition button component includes a fingerprint module and a piezoresistive sensor, and the piezoresistive sensor is two; the fingerprint module is disposed on the cover plate. The inner side, and the two piezoresistive sensors are respectively located at two sides of the fingerprint module.

Additionally, the electronic device includes a display component with a touch function, the display component further including a display screen and a touch sensor; the display screen is located between the cover plate and the piezoresistive sensor; a touch sensor is located between the cover plate and the display screen, or the touch sensor is integrated inside the display screen, wherein the piezoresistive sensor is a transparent material; or the touch sensor is located on the cover plate and the The piezoresistive sensor is fixed to the piezoresistive sensor, wherein the piezoresistive sensor is a transparent material.

DRAWINGS

The one or more embodiments are exemplified by the accompanying drawings in the accompanying drawings, and FIG. The figures in the drawings do not constitute a scale limitation unless otherwise stated.

1 is a schematic structural view of a pressure detecting scheme of an electronic device in the prior art;

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

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

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

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

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

7 is a schematic view showing a first layout manner of a resistor unit on a substrate according to an embodiment;

8 is a schematic view showing a second layout manner of a resistor unit on a substrate in an embodiment;

9 is a schematic view showing a third layout manner of a resistor unit on a substrate according to an embodiment;

10 is a schematic diagram of a full bridge topology of a piezoresistive sensor in which each bridge arm is composed of two resistance units according to the first embodiment;

11 is a schematic view showing a first layout manner in which a resistor unit is dispersedly arranged on both sides of a substrate in an embodiment;

FIG. 12 is a diagram showing a second layout manner in which a resistor unit is dispersedly arranged on both sides of a substrate in an embodiment; FIG. intention;

13 is a schematic view showing a third layout manner in which a resistor unit is dispersedly arranged on both sides of a substrate in an embodiment;

14 is a schematic diagram showing a second layout manner in which a resistor unit is dispersedly disposed on two substrates in an embodiment;

15 is a schematic view showing a third layout manner in which a resistor unit is dispersedly disposed on two substrates in an embodiment;

16 is a schematic structural view of a rectangular piezoresistive sensor according to an embodiment;

17 is a schematic structural view of a piezoresistive sensor of a serpentine resistance layer according to the first embodiment;

18 is a schematic structural view of a loop-shaped resistor laminated resistance sensor according to the first embodiment;

19 is a cross-sectional view of a piezoresistive sensor formed by a first processing process in an embodiment;

20 is a cross-sectional view of a piezoresistive sensor formed by a second processing process in an embodiment;

21 is a cross-sectional view of a piezoresistive sensor formed by a third processing process in an embodiment;

Figure 22 is a cross-sectional view of a keyboard in accordance with a third embodiment;

23 is a schematic structural view of a mouse according to a third embodiment;

24 is a schematic structural view of a virtual button stack according to a third embodiment;

Figure 25 is a cross-sectional view of a virtual key in accordance with a third embodiment;

26 is a force analysis diagram of a virtual button according to a third embodiment;

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

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

29 is a cross-sectional view of a fingerprint recognition button assembly having two piezoresistive sensors in accordance with a third embodiment;

Figure 30 is a cross-sectional view of a fingerprint recognition assembly having a groove on a cover plate according to a third embodiment;

Figure 31 is a cross-sectional view of a fingerprint recognition button assembly having a groove on both the upper and lower sides of the cover plate according to the third embodiment;

32 is a cross-sectional view of a fingerprint recognition button assembly having a through hole in a cover plate according to a third embodiment;

Figure 33 is a cross-sectional view of a fingerprint recognition button assembly having a piezoresistive sensor in accordance with a third embodiment;

Figure 34 is a cross-sectional view of a fingerprint recognition button assembly with two solder joints in accordance with a third embodiment;

Figure 35 is a cross-sectional view of a fingerprint recognition button assembly with a solder joint in accordance with a third embodiment;

Figure 36 is a cross-sectional view of a display assembly in which a touch sensor is positioned between a cover and a display screen in accordance with a third embodiment;

37 is a cross-sectional view of a display assembly integrated with a touch sensor inside a display screen according to a third embodiment;

38 is a cross-sectional view of a display assembly in which a touch sensor is positioned between a cover and a piezoresistive sensor in accordance with a third embodiment;

Figure 39 is a cross-sectional view of an electronic device in accordance with a third embodiment.

detailed description

In order to make the objects, technical solutions, and advantages of the present invention more apparent, the embodiments of the present invention will be described in detail below. However, one of ordinary skill in the art will appreciate that In the various embodiments of the present invention, numerous technical details are set forth to provide the reader with a better understanding of the present application. However, the technical solutions 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 invention relates to a piezoresistive sensor. As shown in FIG. 1, the piezoresistive sensor includes a substrate and a half bridge piezoresistive sensing unit. The half-bridge piezoresistive sensing unit can suppress temperature drift and increase the amount of signal when the pressure detection function is implemented. The half-bridge piezoresistive sensing unit comprises two bridge arms, wherein the two bridge arms are connected in series; wherein the connection ends of the two bridge arms lead to the signal acquisition end; the open ends of the two bridge arms respectively lead to the excitation signal application ends; The bridge arm includes at least one resistor unit, and the resistor unit is located on the substrate, wherein the two bridge arms include the same number of resistor units.

It should be noted that the excitation signal application terminal is used to apply a high level or a low level. Specifically, as shown in FIG. 2, the connection ends of the two bridge arms lead to the signal acquisition terminal IN. The two bridge arms are a first bridge arm 6 and a second bridge arm 7, respectively. The excitation signal application terminal drawn from the open end of the first bridge arm 6 is used to apply a high level (i.e., a voltage VDD can be applied to the open end of the first bridge arm 6). The excitation signal application terminal drawn from the open end of the second bridge arm 7 is used to apply a low level (ie, the open end of the second bridge arm can be grounded to GND). The substrate can be, but is not limited to, a printed circuit board PCB board. The material of the substrate may be, but not limited to, a polyimide PI material, a polyester resin PET material, a glass or a polymethyl methacrylate PMMA material. As shown in FIG. 3, it is worth mentioning that the piezoresistive sensor is a half bridge topology unit structure. In order to distinguish from the full bridge piezoresistive sensor. Piezoresistive sensors can 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 collecting end IN of the half-bridge piezoresistive sensor 10 is connected to the preamplifier unit 803 through the multiplexing switch unit 801, and then passes through the analog-to-digital conversion circuit unit 804, and is connected to the processor unit 805 for processing. The unit 805 is connected to the main control chip 9. The excitation signal application end 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 connected 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, which affects the resistance of the first bridge arm 6 and the resistance of the second bridge arm 7. Partial pressure ratio The signal size of the signal acquisition terminal IN. The detecting chip 8 calculates the magnitude of the pressure by detecting a signal change of the signal collecting end IN. When there is temperature influence, the resistance of the first bridge arm 6 and the resistance of the second bridge arm 7 are close to the resistance value caused by the temperature, and the voltage division ratio of the IN point remains substantially unchanged, so the temperature drifts to the IN signal. The influence of signal changes caused by the point is limited, so the influence of temperature drift can be suppressed.

In addition, in order to further suppress temperature drift, the half bridge type piezoresistive sensing unit is two, respectively a first half bridge piezoresistive sensing unit and a second half bridge piezoresistive sensing unit; the first half bridge pressure The excitation signal applying end of the resistance sensing unit is electrically connected to the excitation signal applying end of the second half bridge piezoresistive sensing unit. Specifically, the signal application end of the first half bridge is connected to the signal application end of the second half bridge. The ground end of the first half bridge is connected to the ground end 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 Figure 4, the two half bridges are connected in parallel to form a full bridge topology. The resistor unit is four, which is a full bridge topology formed by the first resistor unit 101, the second resistor unit 102, the third resistor unit 103, and the fourth resistor unit 104, and the equivalent circuit 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 respectively correspond to the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are respectively four bridge arms of a full bridge topology. This 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 terminals, which are IN+ and IN-. The two differential signal inputs, IN+ and IN-, are connected to the detection chip. When pressure is applied to the piezoresistive sensor, it will affect the voltage division ratio of R1 and R2, affecting the partial pressure ratio of R3 and R4. The influence ratios of the two are inconsistent, which affects the differential signal size between IN+ and IN-. When there is temperature influence, the resistance of R1 and R2, R3 and R4 are affected by the temperature drift. The affected partial pressure ratios at the IN+ and IN- terminals are essentially unaffected by temperature. Thus, the influence of the differential signal size between IN+ and IN- is weak, and most of the signals detected by the chip are due to the useful signal changes generated by the pressing, and the hardware topology suppresses the influence of temperature drift. It is worth mentioning that the piezoresistive sensor is a full-bridge topology unit structure, which can be called a full-bridge piezoresistive sensor. As shown in FIG. 6, in a practical application, the full bridge piezoresistive sensor 11 is connected to the main control chip 9 through the detecting 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 passed through the analog-to-digital conversion circuit unit 804 to the processor unit 805. The processor unit 805 is connected to the main control chip 9. Connecting IN+ and IN- to separate detection channels helps to improve detection speed. It is also possible to use one of the detection channels to perform one-to-one sampling detection for each full-bridge piezoresistive sensor 11 forming a full-bridge topology unit in a polling manner.

It should be noted that the resistor units may be juxtaposed on the substrate. As shown in FIG. 7 , the full-bridge piezoresistive sensor is described as an example. The resistance unit may be four and juxtaposed on the substrate 12 . Four resistor units are juxtaposed on the substrate 12. The direction of the figure is taken as an example for explanation. From left to right are, in order, a first resistance unit, a second resistance unit, a third resistance unit, and a fourth resistance unit. The upper terminals of the four resistor units are IN+, IN+, IN-, IN- from left to right. The lower terminals of the four resistor units are VDD, GND, VDD, and GND from left to right. As shown in FIG. 8, the four resistor units may also be arranged on the substrate 12 in the following manner. The upper terminals of the four resistor units are IN-, IN+, IN+, IN- from left to right. The lower terminals of the four resistor units are VDD, GND, VDD, and GND from left to right. As shown in FIG. 9, the four resistor units may also be arranged on the substrate 12 in the following manner. The upper terminals of the four resistor units are IN+, IN-, IN+, IN- from left to right. The lower terminals of the four resistor units are GND, VDD, VDD, GND, etc. from left to right. It is not listed here.

As shown in FIG. 10, each bridge arm of the full bridge can 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. It may also be that three resistor units are connected in series, or four resistor units may be connected in series, etc., which are not listed here. Moreover, in practical applications, each bridge arm may also be composed of two resistor units connected in parallel in the case where the resistance of the resistor unit is allowed.

In this embodiment, the dispersion of the resistor unit on both sides of the substrate helps to enhance the same deformation. Use the detection signal amount below. Specifically, when the resistor unit forms a full bridge topology, the resistor unit is dispersedly disposed on both sides of the substrate, and a larger differential signal variation can be obtained under the same force. Take Figure 5 for example. If R1 and R2 are designed on the same level, when the same deformation is applied to both, the changes will be similar. This causes the change in the voltage division ratio at IN+ to be small, and the amount of signal generated is small, as is the signal at the same IN-. However, if R1 and R2 are designed on different levels, and the same deformation acts on two voltage-dividing resistors, the change of R1 and the change of R2 are different at different levels. Therefore, the influence of the partial pressure ratio at IN+ is increased, and the effect of increasing the signal variation is achieved. Similarly, the signal at IN- is also at different levels of R3 and R4, which also increases the effect of signal variation. However, if the signals at IN+ and IN- are both increased in proportion, the differential signal between IN+ and IN- is still weak. For example, although R1 and R2 are in different layers, R3 and R4 are in different layers; however, R1 and R3 are in the same layer, and R2 and R4 are in the same layer. In this design, the signal is increased in a single half-bridge, but the differential signal between IN+ and IN- between the two half-bridges is still not increased. Therefore, the full-bridge topology at this time also needs to design the diagonal arms of R1 and R4 in the same layer, and the pair of bridges R3 and R2 are designed on the same layer, so that the difference between IN+ and IN- can be increased. signal. If it is only a half-bridge topology, then the two resistor units are at different levels to facilitate the inspection signal. In the case of a full-bridge topology, the two resistor units in each half-bridge should be at different levels, and the diagonal resistor units should be at the same level. As shown in FIG. 11, a preferred layout is to arrange two resistor units on one side of the substrate 12. Two resistor units are arranged on the other side of the substrate 12. Specifically, the illustrated direction will be described 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 are located at the right side 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 are located at the left side portion of the substrate 12. Alternatively, 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 are located on the left side portion of the substrate 12. the first The resistance unit 101 and the fourth resistance unit 104 are located on the lower surface of the substrate 12, and are located at the right side portion of the substrate 12 or the like. It is not listed here. It should be noted that, in the embodiment, the specific position and the specific number of the resistor unit on each side of the substrate 12 are not limited.

In an actual design process, the substrate may be designed to be at least two; each of the substrates is provided with the resistor unit. As shown in FIG. 14 , two substrates are used as an example. The two substrates are the first substrate 121 and the second substrate 122 , respectively. Two resistance units are arranged on the first substrate 121. Two resistor units are arranged on the second substrate 122. One side of the first substrate 121 having no resistance unit is disposed opposite to the side of the second substrate 122 having the resistance unit. Further, 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 arranged on the first substrate 121. Two resistor units are arranged on the second substrate 122. One side of the first substrate 121 having the resistance unit is disposed opposite to the side of the second substrate 122 having the resistance unit. Further, the resistance unit on the first substrate 121 and the resistance unit on the second substrate 122 are respectively fixed to both faces of the adhesive 13 .

It should be noted that the resistance unit includes a resistance layer and two lead terminals. The resistive layer can be, but is not limited to, carbon or graphene. The material of the two lead terminals may be, but not limited to, copper or silver paste. It should also be noted that the length, width, and thickness of the resistive layer will affect the resistance of the resistive resistor unit. By adjusting the length, width and thickness of the resistance layer, a piezoresistive sensor adapted to the range of resistance values of the detection chip circuit can be obtained. In a practical application, the resistor unit 14 is connected to the main control chip 9 through the detecting chip 8. The excitation signal unit 802 applies an excitation signal to the resistance unit 14. The plurality of processing units inside the detection chip 8 sample the resistance unit 14. The resistance value change of the resistance unit 14 can be detected in real time, and the analog signal change of the resistance value is converted into a digital signal, and then the corresponding pressure value is obtained by the arithmetic processing and reported to the main control chip 9. After receiving the pressure information, the main control chip 9 compares with the preset threshold, and then performs corresponding application command processing. Here, the shape of the resistance layer 15 may be, but not limited to, a rectangle as shown in FIG. 16; a serpentine shape as shown in FIG. 17; or a shape as shown in FIG.

1. Two lead terminals and a resistive layer are attached to the substrate by the following process:

As shown in FIG. 19, two lead terminals 16 are applied to the substrate 12 at intervals. Resistance layer 15 is coated on the substrate 12 and located between the two lead terminals 16. Wherein, the two ends of the resistive layer 15 extend to the two lead terminals 16 respectively, which helps to ensure that the lead terminal 16 and the resistive layer 15 are in full contact conduction. An insulating layer 17 is applied 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 to protect the two lead terminals 16 and the resistance layer 15 from oxidation.

2. The two lead terminals and the resistive layer are attached to the substrate by the following process:

As shown in FIG. 20, the resistance layer 15 is coated on the substrate 12. Two lead terminals 16 are respectively coated on the substrate 12 and located at both ends of the resistance layer 15. Wherein, the two lead terminals 16 extend to the resistance layer 15 respectively, which helps to ensure that the lead terminal 16 and the resistance layer 15 are in full contact conduction. An insulating layer 17 is applied 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 to protect the two lead terminals 16 and the resistance layer 15 from oxidation.

3. Two lead terminals and a resistive layer are attached to the substrate by the following process:

As shown in FIG. 21, the resistance layer 15 and the two lead terminals 16 are respectively coated on the substrate 12, and the two lead terminals 16 are located at both ends of the resistance layer 15. Among them, the two lead terminals 16 are all hard lead terminals. The application of the silver paste 18 above the resistance layer 15 and the lead terminals 16 helps to ensure that the lead terminals 16 are sufficiently in contact with the resistance layer 15. An insulating layer 17 is applied 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 to protect the two lead terminals 16 and the resistance layer 15 from oxidation.

Through the above, it is not difficult to find that the present embodiment adopts a design of a piezoresistive sensor including a substrate and a half-bridge piezoresistive sensing unit, so that the piezoresistive sensor can suppress temperature drift when implementing the pressure detecting function, and can also increase signal. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The internal space requirements of the entire electronic device are relatively low and easy to promote. The assembly of the piezoresistive sensor to the electronic device is relatively simple and helps to make the piezoresistive sensing The device is integrated into various components of the electronic device to achieve a variety of rich applications.

A second embodiment of the present invention relates to a pressure detecting device including the piezoresistive sensor and processor of the first embodiment; a piezoresistive sensor for receiving pressure; and a processor for outputting the piezoresistive sensor The signal is processed to obtain pressure information for the pressure.

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

In practical applications, the pressure sensing device also includes a cover. The cover is covered on the piezoresistive sensor, and the piezoresistive sensor is attached to the cover by adhesive. a cover plate for receiving pressure and conducting pressure to the piezoresistive sensor. Among them, the piezoresistive sensor can be attached to the cover by an adhesive.

As shown in FIG. 22, the electronic device may include a keyboard having a pressure detecting function. A number of keyboard characters are printed on the cover 19. Specifically, the side of the cover plate 19 on which the keyboard characters are not printed is attached with a piezoresistive sensor through the adhesive 13 . Each keyboard character covers at least one piezoresistive sensor 20.

As shown in FIG. 23, the electronic device may include a mouse, and the mouse has a pressure detecting function. The cover plate 19 is a housing 191 corresponding to the left mouse button and a housing 192 corresponding to the right button area of the mouse.

In a practical application, as shown in FIG. 24 and FIG. 25, the electronic device may further include a button component having a pressure detecting function. The button component can be a virtual button. Preferably, the button assembly further includes a touch sensor 21; the touch sensor 21 is located below the cover plate 19. It is worth mentioning that the cover can be the display area at this time. It can also be a button area below the display area. A piezoresistive sensor 22 can be disposed below the electronic device virtual button, i.e., the cover plate 19. Also, in a practical application, a display screen 23 is provided between the cover 19 and the piezoresistive sensor 22. In this way, the function of the button component is enriched, not only can the touch be recognized, but also the pressure can be recognized, thereby providing more applications for the operation of the button component. For example, if the button 1 is pressed by the finger 1 to exceed a certain threshold, the corresponding setting function is responded to. Such as: call out voice assistant, search function or mode switch. In the cover A touch sensor 21 is attached to the lower side of the 19 by the adhesive 13 . Alternatively, a display screen 23 is attached to the underside of the cover plate 19 by an adhesive 13, and a piezoresistive sensor 22 is fixed below the display screen 23. Although only the touch sensor 21 is under the finger pressing area A, the piezoresistive sensor 22 is not disposed. However, as is apparent from Fig. 26, according to the structural mechanics deformation principle, when the finger 1 is pressed against the edge region of the force receiving cover 19 supported by the fulcrum B, not only the finger pressing region A is bent downwardly. The non-pressing area is also deformed. The deformation from the broken line to the solid line position in Fig. 28 is shown. It is thus possible to make application design using this mechanical property. Since the force is transmitted when the finger 1 is pressed to the finger pressing area A, the display screen 23 area is also deformed. Therefore, it is also possible to identify the key pressure using the piezoresistive sensor 22 in the area of the display screen 23.

In addition, the button 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 19 is the side bead of the electronic device. It is worth mentioning that the assembly of the side of the bread can be a metal or non-metallic material assembly, or a hybrid assembly of metal and non-metal materials. The piezoresistive sensor 22 is attached to the inner side of the side bun by the adhesive 13 . The side of the side of the bread can be set in a convex form to ensure the finger pressing effect. As shown in FIG. 28, there are at least two piezoresistive sensors 22, and a protrusion buckle 24 may be disposed between adjacent piezoresistive sensors 22. Specifically, there may be two side buttons, such as a power button and a volume button. When the side keys are the power key and the volume key, the power key and the volume key are arranged with the piezoresistive sensor 22. Both piezoresistive sensors 22 are attached to the inside of the side bun by adhesive glue 13. Among them, the convex buckle 24 can increase the strength of the cover. It is worth mentioning that the piezoresistive sensor 22 is provided with a convex buckle 24 on both sides. Preferably, the height of the raised buckle 24 is greater than the height of the piezoresistive sensor 22. Specifically, the height of the convex buckle 24 is greater than the sum of the thicknesses of the piezoresistive sensor 22 and the adhesive 13 . The raised buckle 24 is equivalent to assuming that there are a plurality of fulcrums for the bead 19 to form a beam structure, similar to the mechanical structure of Fig. 28, which not only can strengthen the reinforcement edge, but also increase the shape variable generated. .

In addition, the button component can also be a fingerprint recognition button component. As shown in FIG. 29, the piezoresistive sensor 22 has two. The fingerprint identification button component also includes a fingerprint module 25. The fingerprint module 25 is fixed to the inner side of the cover plate 19, and the two piezoresistive sensors 22 are respectively located at two sides of the fingerprint mold 25. In order Increasing the sensitivity of fingerprint recognition, as shown in FIGS. 30 and 31, a recess 26 may be provided on at least one side 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; or, a groove 26 may be provided on the lower surface of the cover plate 19; or, the upper and lower surfaces of the cover plate 19 may be simultaneously provided. The groove 26; or, as shown in FIG. 32, the cover plate 19 is provided with a through hole, and the through hole corresponds 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 being respectively located on both sides of the fingerprint die 25. For example, the fingerprint module 25 is fixed to the inner side of the cover 19, and the piezoresistive sensor 22 is fixed to the fingerprint module 25 by the adhesive 13 . It should be noted that, as shown in FIG. 34 and FIG. 35, the piezoresistive sensor 22 can be, but is not limited to, fixed to the fingerprint module 25 by solder joints or glue, rubberized foam, or the like. In order to protect the piezoresistive sensor 22 from damage, a bump 28 may be provided on one side of the piezoresistive sensor 22 that faces away from the solder joint.

The electronic device may further include a display component with a touch function, the display component has a pressure detecting function, and the display component further includes a display screen and a touch sensor. The display is located between the cover and the piezoresistive sensor. Among them, 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. Further, the touch sensor 30 is fixed to the cover 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 19 and the display screen 29 are fixed by an 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. Further, the cover 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 an adhesive 13 .

It is not difficult to find that the present embodiment corresponds to the first embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still effective in the present embodiment, and are not described herein again in order to reduce repetition. Accordingly, the phase mentioned in this embodiment The technical details can also be applied in the first embodiment.

From the above, it is not difficult to find that the present embodiment allows the piezoresistive sensor to suppress temperature drift when the pressure detecting function is implemented. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The internal space requirements of the entire electronic device are relatively low and easy to promote. The assembly of the piezoresistive sensor to the electronic device is relatively simple, and it is helpful to fuse the piezoresistive sensor to various components of the electronic device to realize various rich applications.

As a preferred embodiment, as shown in FIG. 39, the electronic device may further include a structural member 31. The pressure detecting device is a display component 32 with a touch function. There is a gap 33 between the display assembly 32 and the structural member 31. Among them, the gap 33 is filled with foam. It is worth mentioning that the structural member 31 can 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 effective in the present embodiment, and the technical effects that can be achieved in the first and second embodiments can also be implemented in the present embodiment, in order to reduce repetition, here No longer. Accordingly, the related technical details mentioned in the present embodiment can also be applied to the first and second embodiments.

From the above, it is not difficult to find that the present embodiment allows the piezoresistive sensor to suppress temperature drift and increase the amount of signal when the pressure detecting function is realized. Moreover, the present embodiment can avoid the structural design of the capacitive sensor plate. The internal space requirements of the entire electronic device are relatively low and easy to promote. The assembly of the piezoresistive sensor to the electronic device is relatively simple, and it is helpful to fuse the piezoresistive sensor to various components of the electronic device to realize various rich applications.

A person skilled in the art can understand that the above embodiments are specific embodiments for implementing the present invention, and various changes can be made in the form and details without departing from the spirit and scope of the present invention. range.

Claims

A piezoresistive sensor, comprising: a substrate and a half bridge piezoresistive sensing unit;

The half bridge piezoresistive sensing unit includes two bridge arms, and the two bridge arms are connected in series; wherein the connection ends of the two bridge arms lead to a signal collecting end; the open ends of the two bridge arms respectively Introducing an excitation signal application end;

Each of the bridge arms includes at least one resistor unit, the resistor unit being located on the substrate, wherein the two bridge arms comprise the same number of resistor units.
The piezoresistive sensor according to claim 1, wherein the half bridge piezoresistive sensing unit is two, respectively a first half bridge piezoresistive sensing unit and a second half bridge piezoresistive Sensing unit

The excitation signal application end of the first half bridge piezoresistive sensing unit and the excitation signal application end of the second half bridge piezoresistive sensing unit are electrically connected.
The piezoresistive sensor according to claim 2, wherein the first half bridge piezoresistive sensing unit and the second half bridge piezoresistive sensing unit each comprise two resistor units, the substrate One of the two resistor units is disposed on one side, and two resistor units are disposed on the other side of the substrate.
The piezoresistive sensor according to any one of claims 1 to 3, wherein the substrate is at least two;

The resistor unit is disposed on each of the substrates.
The piezoresistive sensor according to claim 1, wherein the one resistor unit comprises a resistance layer and two lead terminals;

The two lead terminals and the resistance layer are attached to the substrate by a process of: coating the two lead terminals on the substrate at intervals, and coating the resistance layer on the substrate And the resistance layer is located between the two lead terminals; wherein, the two ends of the resistance layer respectively Extending to the two lead terminals, coating an insulating layer over the resistive layer and the lead terminal such that the insulating layer covers the resistive layer and the lead terminal;

Alternatively, the resistive layer is coated on the substrate, and the two lead terminals are respectively coated on the substrate and located at two ends of the resistive layer; wherein the two lead terminals are respectively Extending to the resistive layer, coating an insulating layer over the resistive layer and the lead terminal such that the insulating layer covers the resistive layer and the lead terminal;

Alternatively, the resistance layer and the two lead terminals are respectively coated on the substrate, and the two lead terminals are located at both ends of the resistance layer; wherein the two lead terminals are hard a lead terminal, a silver paste is coated on the upper side of the resistance layer and the lead terminal, and an insulating layer is coated on the resistance layer, the lead terminal and the silver paste to cover the insulating layer The resistive layer, the lead terminal, and the silver paste are described.
The piezoresistive sensor according to claim 5, wherein the resistive layer has a rectangular shape, a serpentine shape or a curved shape.
A pressure detecting device comprising the piezoresistive sensor and processor according to any one of claims 1 to 6;

The piezoresistive sensor is configured to receive pressure;

The processor is configured to process a signal output by the piezoresistive sensor to obtain pressure information of the pressure.
An electronic device having a pressure detecting function, comprising: the pressure detecting device according to claim 7.
The electronic device according to claim 8, wherein the electronic device further comprises a cover;

The cover plate is covered on the piezoresistive sensor, and the piezoresistive sensor is attached to the cover plate by an adhesive;

The cover plate is adapted to receive pressure and conduct the pressure to the piezoresistive sensor.
The electronic device of claim 8 wherein said electronic device comprises side key assemblies, each of said side key assemblies comprising a piezoresistive sensor.
The electronic device according to claim 10, wherein the side key assemblies are at least two, and the adjacent ones of the piezoresistive sensors are provided with a protruding buckle, and the height of the protruding buckle Greater than the height of the piezoresistive sensor.
The electronic device according to claim 8, wherein the electronic device comprises a fingerprint recognition button component having a pressure detecting function, the fingerprint recognition button component comprises a fingerprint module and a piezoresistive sensor, and the piezoresistive type The sensor module is disposed on the inner side of the cover plate, and the two piezoresistive sensors are respectively located on two sides of the fingerprint module.
The electronic device according to claim 12, wherein at least one side of the cover plate is provided with a groove, and the groove corresponds to a position of the fingerprint module;

The cover plate is provided with a through hole, and the through hole corresponds to a position of the fingerprint module.
The electronic device according to claim 8, wherein the electronic device comprises a display component with a touch function, the display component further comprising a display screen and a touch sensor; the display screen is located at the cover plate and the Between the piezoresistive sensors; the touch sensor is located between the cover plate and the display screen, or the touch sensor is integrated inside the display screen;

Alternatively, the touch sensor is located between the cover plate and the piezoresistive sensor; the display screen is fixed to the piezoresistive sensor.