Pressure sensor and electronic device

Abstract

A pressure sensor and an electronic device. The pressure sensor comprises a flexible circuit board (110) and a plurality of pressure-sensitive adhesive resistors, wherein the plurality of pressure-sensitive adhesive resistors comprise pressure-sensitive adhesive resistors R1, R2, R3, R4, R5 and R6; the flexible circuit board (110) comprises a first surface (A) and a second surface (B), which are opposite each other; the pressure-sensitive adhesive resistors R1, R3 and R5 are arranged on the first surface (A), and the pressure-sensitive adhesive resistors R2, R4 and R6 are arranged on the second surface (B); a through hole (C), which connects the first surface (A) and the second surface (B), is provided on the flexible circuit board (110), and the pressure-sensitive adhesive resistors R1, R2, R3 and R4 at least partially cover the through hole (C); and the pressure-sensitive adhesive resistors R1, R2, R5 and R6 are electrically connected to form a first Wheatstone bridge, and the pressure-sensitive adhesive resistors R3, R4, R5 and R6 are electrically connected to form a second Wheatstone bridge.

Description

TECHNICAL FIELD

[0002] This application relates to the field of sensor technologies, and in particular,to a pressure sensor and an electronic device.BACKGROUND

[0003] With increasing requirements on product appearance, a design of hiddenkeys is increasingly present on flagship and high-end smartphones. A common designscheme is to use a pressure sensor as a hidden key.

[0004] In the design scheme in which a pressure sensor is used as a hidden key,generally pressure sensitive adhesive resistors are used to form a Wheatstone bridge, soas to convert the pressure received into a voltage difference for output. Resistivity ofthe pressure sensitive adhesive resistor changes with temperature. In a case that asmartphone stays in a high or low temperature environment for a long time, for example,the smartphone has been placed outdoor in the sunlight in summer, or the smartphonehas been placed outdoor in a low temperature in winter, after a user picks up thesmartphone and presses the hidden key, although the user's finger has been lifted, thepressure sensitive adhesive resistor of the hidden key still generates and outputs avoltage difference due to a temperature effect. As a result, the smartphone considersthat the user presses and holds the hidden key without releasing it, which in turn leadsto a problem that the smartphone is switched off or does not respond to the user'sanother press on the hidden key.

[0005] In this application, the temperature effect refers to a phenomenon that whena hot or cold housing of a smartphone is touched by a user finger or another thermostaticobject, resistivity of pressure sensitive adhesive at different locations changesinconsistently due to different distances between the pressure sensitive adhesive atdifferent locations and the finger.SUMMARY

[0006] An objective of embodiments of this application is to provide a pressuresensor and an electronic device, to compensate for a signal generated by the pressuresensor due to a temperature effect, so as to guarantee measurement accuracy of thepressure sensor.

[0007] According to a first aspect, an embodiment of this application provides apressure sensor, including a flexible printed circuit board and multiple pressuresensitive adhesive resistors, where the multiple pressure sensitive adhesive resistorsinclude a pressure sensitive adhesive resistor R1, a pressure sensitive adhesive resistorR2, a pressure sensitive adhesive resistor R3, a pressure sensitive adhesive resistor R4,a pressure sensitive adhesive resistor R5, and a pressure sensitive adhesive resistor R6;the flexible printed circuit board includes a first surface and a second surface that areopposite each other; the pressure sensitive adhesive resistor R1, the pressure sensitiveadhesive resistor R3, and the pressure sensitive adhesive resistor R5 are disposed onthe first surface, and the pressure sensitive adhesive resistor R2, the pressure sensitiveadhesive resistor R4, and the pressure sensitive adhesive resistor R6 are disposed onthe second surface; the flexible printed circuit board is provided with a through holethat allows the first surface to communicate with the second surface, and the throughhole is at least partially covered by the pressure sensitive adhesive resistor R1, thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, andthe pressure sensitive adhesive resistor R4; and the pressure sensitive adhesive resistorR1, the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistorR5, and the pressure sensitive adhesive resistor R6 are electrically connected to form afirst Wheatstone bridge, and the pressure sensitive adhesive resistor R3, the pressuresensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and thepressure sensitive adhesive resistor R6 are electrically connected to form a secondWheatstone bridge.

[0008] According to a second aspect, an embodiment of this application providesan electronic device, including the pressure sensor according to the first aspect, where the pressure sensor is fastened inside a device housing as a hidden key.

[0009] According to the pressure sensor and electronic device provided in theembodiments of this application, multiple pressure sensitive adhesive resistors aredisposed on a flexible printed circuit board. The multiple pressure sensitive adhesiveresistors include a pressure sensitive adhesive resistor R1, a pressure sensitive adhesiveresistor R2, a pressure sensitive adhesive resistor R3, a pressure sensitive adhesiveresistor R4, a pressure sensitive adhesive resistor R5, and a pressure sensitive adhesiveresistor R6, and the flexible printed circuit board includes a first surface and a secondsurface that are opposite each other. The pressure sensitive adhesive resistor R1, thepressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R5are disposed on the first surface, and the pressure sensitive adhesive resistor R2, thepressure sensitive adhesive resistor R4, and the pressure sensitive adhesive resistor R6are disposed on the second surface. The flexible printed circuit board is further providedwith a through hole that allows the first surface to communicate with the second surface,and the through hole is at least partially covered by the pressure sensitive adhesiveresistor R1, the pressure sensitive adhesive resistor R2, the pressure sensitive adhesiveresistor R3, and the pressure sensitive adhesive resistor R4. The pressure sensitiveadhesive resistor R1, the pressure sensitive adhesive resistor R2, the pressure sensitiveadhesive resistor R5, and the pressure sensitive adhesive resistor R6 are electricallyconnected to form a first Wheatstone bridge, and the pressure sensitive adhesive resistorR3, the pressure sensitive adhesive resistor R4, the pressure sensitive adhesive resistorR5, and the pressure sensitive adhesive resistor R6 are electrically connected to form asecond Wheatstone bridge. Voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6is used to compensate for voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, thepressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R4,so that a voltage signal output by the pressure sensor includes only a voltage signalgenerated by the pressure action, thereby eliminating the impact of temperature on thevoltage signal output by the pressure sensor, and implementing temperaturecompensation for the pressure sensor. This can guarantee measurement accuracy of thepressure sensor in a high or low temperature environment, and resolve problems suchas false alarm or release delay of the pressure sensor caused by the temperature effect.BRIEF DESCRIPTION OF DRAWINGS

[0010] The drawings described herein are intended for a further understanding ofthis application and constitute a part of this application. Example embodiments of thisapplication and descriptions thereof are intended to explain this application, and do notconstitute any inappropriate limitation on this application. In the accompanyingdrawings:

[0011] FIG. 1 is a schematic diagram of a composition structure of a pressure sensoraccording to an embodiment of this application;

[0012] FIG. 2 is a schematic diagram of a working principle of a Wheatstone bridgein a pressure sensor according to an embodiment of this application;

[0013] FIG. 3 is a schematic diagram of a pressure action on a pressure sensoraccording to an embodiment of this application; and

[0014] FIG. 4 is a schematic diagram of another composition structure of a pressuresensor according to an embodiment of this application.DESCRIPTION OF EMBODIMENTS

[0015] The following clearly and completely describes the technical solutions inthe embodiments of this application with reference to the accompanying drawings inthe embodiments of this application. Apparently, the described embodiments are somebut not all of the embodiments of this application. All other embodiments obtained bya person of ordinary skill in the art based on the embodiments of this application withoutcreative efforts shall fall within the protection scope of this application.

[0016] FIG. 1 is a schematic diagram of a composition structure of a pressure sensoraccording to an embodiment of this application. As shown in FIG. 1, the pressure sensorin this embodiment of this application includes a flexible printed circuit board (FlexiblePrinted Circuit, FPC) 110 and multiple pressure sensitive adhesive resistors. Multiplepressure sensitive adhesive resistors may be printed on the flexible printed circuit boardto form a flexible printed circuit assembly (Flexible Printed Circuit Assembly, FPCA).The multiple pressure sensitive adhesive resistors include a pressure sensitive adhesiveresistor R1, a pressure sensitive adhesive resistor R2, a pressure sensitive adhesiveresistor R3, a pressure sensitive adhesive resistor R4, a pressure sensitive adhesiveresistor R5, and a pressure sensitive adhesive resistor R6. The flexible printed circuitboard 110 includes a first surface A and a second surface B that are opposite each other.The pressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R3,and the pressure sensitive adhesive resistor R5 are disposed on the first surface A, andthe pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R4,and the pressure sensitive adhesive resistor R6 are disposed on the second surface B.The flexible printed circuit board 110 is further provided with a through hole C thatallows the first surface A to communicate with the second surface B, and the throughhole C is at least partially covered by the pressure sensitive adhesive resistor R1, thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, andthe pressure sensitive adhesive resistor R4. The pressure sensitive adhesive resistor R1,the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R5,and the pressure sensitive adhesive resistor R6 are electrically connected to form a firstWheatstone bridge, and the pressure sensitive adhesive resistor R3, the pressuresensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and thepressure sensitive adhesive resistor R6 are electrically connected to form a secondWheatstone bridge.

[0017] In the pressure sensor provided in this embodiment of this application,multiple pressure sensitive adhesive resistors are disposed on a flexible printed circuitboard. The multiple pressure sensitive adhesive resistors include a pressure sensitiveadhesive resistor R1, a pressure sensitive adhesive resistor R2, a pressure sensitiveadhesive resistor R3, a pressure sensitive adhesive resistor R4, a pressure sensitiveadhesive resistor R5, and a pressure sensitive adhesive resistor R6, and the flexibleprinted circuit board includes a first surface and a second surface that are opposite eachother. The pressure sensitive adhesive resistor R1, the pressure sensitive adhesiveresistor R3, and the pressure sensitive adhesive resistor R5 are disposed on the firstsurface, and the pressure sensitive adhesive resistor R2, the pressure sensitive adhesiveresistor R4, and the pressure sensitive adhesive resistor R6 are disposed on the secondsurface. The flexible printed circuit board is further provided with a through hole thatallows the first surface to communicate with the second surface, and the through holeis at least partially covered by the pressure sensitive adhesive resistor R1, the pressuresensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, and thepressure sensitive adhesive resistor R4. The pressure sensitive adhesive resistor R1, thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R5, andthe pressure sensitive adhesive resistor R6 are electrically connected to form a firstWheatstone bridge, and the pressure sensitive adhesive resistor R3, the pressuresensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and thepressure sensitive adhesive resistor R6 are electrically connected to form a secondWheatstone bridge. Voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6is used to compensate for voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, thepressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R4,so that a voltage signal output by the pressure sensor includes only a voltage signalgenerated by the pressure action, thereby eliminating the impact of temperature on thevoltage signal output by the pressure sensor, and implementing temperaturecompensation for the pressure sensor. This can guarantee measurement accuracy of thepressure sensor in a high or low temperature environment, and resolve problems suchas false alarm or release delay of the pressure sensor caused by the temperature effect.

[0018] The following describes a working principle of the pressure sensoraccording to the embodiments of this application with reference to FIG. 2 to FIG. 3.

[0019] FIG. 2 is a schematic diagram of a working principle of a Wheatstone bridgein a pressure sensor according to an embodiment of this application. As shown in FIG.2, the pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistorR2 are electrically connected, and a first voltage signal Vp11 is generated between thepressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistor R2.Because the pressure sensitive adhesive resistor R1 and the pressure sensitive adhesiveresistor R2 form a bleeder circuit and are connected between a power supply VCC anda ground terminal GND, the first voltage signal Vp11 is a voltage on the pressuresensitive adhesive resistor R2. The pressure sensitive adhesive resistor R3 and thepressure sensitive adhesive resistor R4 are electrically connected, and a second voltagesignal Vp12 is generated between the pressure sensitive adhesive resistor R3 and thepressure sensitive adhesive resistor R4. Because the pressure sensitive adhesive resistorR3 and the pressure sensitive adhesive resistor R4 form a bleeder circuit and areconnected between the power supply VCC and the ground terminal GND, the secondvoltage signal Vp12 is a voltage on the pressure sensitive adhesive resistor R4. Thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6are electrically connected, and a third voltage signal Vp13 is generated between thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6.Because the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesiveresistor R6 form a bleeder circuit and are connected between the power supply VCCand the ground terminal GND, the third voltage signal Vp13 is a voltage on the pressuresensitive adhesive resistor R6. A signal ΔU1 output by the first Wheatstone bridge is adifference between the first voltage signal Vp11 and the third voltage signal Vp13, thatis, ΔU1 = Vp11 - Vp13. A signal ΔU2 output by the second Wheatstone bridge is adifference between the second voltage signal Vp12 and the third voltage signal Vp13,that is, ΔU2 = Vp12 - Vp13. A signal ΔU output by the pressure sensor is a sum of the5 signal ΔU1 output by the first Wheatstone bridge and the signal ΔU2 output by thesecond Wheatstone bridge, that is, ΔU = ΔU1 + ΔU2.

[0020] In a case that the pressure sensor in this embodiment of this application isnot affected by the pressure action and temperature effect, the first voltage signal Vp11,that is, the voltage on the pressure sensitive adhesive resistor R2, is a voltage generatedthrough voltage division of the pressure sensitive adhesive resistor R1 and the pressuresensitive adhesive resistor R2. The second voltage signal Vp12, that is, the voltage onthe pressure sensitive adhesive resistor R4, is a voltage generated through voltagedivision of the pressure sensitive adhesive resistor R3 and the pressure sensitiveadhesive resistor R4. The third voltage signal Vp13, that is, the voltage on the pressuresensitive adhesive resistor R6, is a voltage generated through voltage division of thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6.Because a ratio of the pressure sensitive adhesive resistor R1 to the pressure sensitiveadhesive resistor R2, a ratio of the pressure sensitive adhesive resistor R3 to the pressuresensitive adhesive resistor R4, and a ratio of the pressure sensitive adhesive resistor R5to the pressure sensitive adhesive resistor R6 are equal, voltages generated due tovoltage division of the pressure sensitive adhesive resistor R2, the pressure sensitiveadhesive resistor R4, and the pressure sensitive adhesive resistor R6 are equal, that is,Vp11 = Vp12 = Vp13. In this case, the voltage signal output by the first Wheatstonebridge is ΔU1 = Vp11 - Vp13 = 0, the voltage signal output by the second Wheatstonebridge is ΔU2 = Vp12 - Vp13 = 0, and the voltage signal finally output by the pressuresensor is ΔU = ΔU1 + ΔU2 = 0, so the pressure sensor outputs no signal.

[0021] In a case that the pressure sensor in this embodiment of this application isaffected by the pressure action but not affected by the temperature effect, the firstvoltage signal Vp11, that is, the voltage on the pressure sensitive adhesive resistor R2,is a voltage generated through voltage division of the pressure sensitive adhesiveresistor R1 and the pressure sensitive adhesive resistor R2; the second voltage signalVp12, that is, the voltage on the pressure sensitive adhesive resistor R4, is a voltagegenerated through voltage division of the pressure sensitive adhesive resistor R3 andthe pressure sensitive adhesive resistor R4; and the third voltage signal Vp13, that is,the voltage on the pressure sensitive adhesive resistor R6, is a voltage generated throughvoltage division of the pressure sensitive adhesive resistor R5 and the pressure sensitiveadhesive resistor R6. Because the pressure sensitive adhesive resistor R1, the pressuresensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, and thepressure sensitive adhesive resistor R4 at least partially cover the through hole C, thatis, are in a region of the flexible printed circuit board subjected to the action of pressure,a curvature of such region changes under the action of pressure, as shown in FIG. 3.Therefore, as the curvature of the region of the flexible printed circuit board subjectedto the action of pressure changes, the pressure sensitive adhesive resistor R1 and thepressure sensitive adhesive resistor R3 are squeezed, and the pressure sensitiveadhesive resistor R2 and the pressure sensitive adhesive resistor R4 are stretched, sothat resistivities of the pressure sensitive adhesive resistor R1 and the pressure sensitiveadhesive resistor R3 decrease, and resistivities of the pressure sensitive adhesiveresistor R2 and the pressure sensitive adhesive resistor R4 increase. The pressuresensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, the pressuresensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R4 areaffected by the pressure action, so that a voltage generated due to voltage division ofthe pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistorR3 decreases and a voltage generated due to voltage division of the pressure sensitiveadhesive resistor R2 and the pressure sensitive adhesive resistor R4 increases. Becausethe pressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistorR6 do not cover the through hole C, that is, are located in a region of the flexible printedcircuit board not subjected to the action of pressure, a curvature of such region does notchange under the action of pressure, as shown in FIG. 3. Therefore, the pressuresensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6 are notsqueezed or stretched, and resistivities of the pressure sensitive adhesive resistor R5and the pressure sensitive adhesive resistor R6 do not change. The pressure sensitiveadhesive resistor R5 and the pressure sensitive adhesive resistor R6 are free from theaction of pressure, and a voltage generated due to voltage division of the pressuresensitive adhesive resistor R5 and pressure sensitive adhesive resistor R6 does notchange.

[0022] In addition, before being subjected to the action of pressure, both the ratioof the pressure sensitive adhesive resistor R1 to the pressure sensitive adhesive resistorR2 and the ratio of the pressure sensitive adhesive resistor R3 to the pressure sensitiveadhesive resistor R4 are equal to the ratio of the pressure sensitive adhesive resistor R5to the pressure sensitive adhesive resistor R6. Therefore, after being subjected to theaction of pressure, the voltages generated due to the voltage division of the pressuresensitive adhesive resistor R2 and pressure sensitive adhesive resistor R4 both aregreater than the voltage generated due to the voltage division of the pressure sensitiveadhesive resistor R6, that is, Vp11 > Vp13, and Vp12 > Vp13. In this case, the voltagesignal output by the first Wheatstone bridge, ΔU1 = Vp11 - Vp13 > 0, is an electricalsignal generated due to pressure on the first Wheatstone bridge, the voltage signaloutput by the second Wheatstone bridge, ΔU2 = Vp12 - Vp13 > 0, is an electricalsignal generated due to pressure on the second Wheatstone bridge, and the voltagesignal finally output by the pressure sensor is ΔU = ΔU1 + ΔU2 > 0. The pressuresensor converts the pressure received into an electrical signal for output.

[0023] In a case that the pressure sensor in this embodiment of this application isaffected by the pressure action and the temperature effect, the first voltage signal Vp11,that is, the voltage on the pressure sensitive adhesive resistor R2, is a voltage generatedthrough voltage division of the pressure sensitive adhesive resistor R1 and the pressuresensitive adhesive resistor R2; the second voltage signal Vp12, that is, the voltage onthe pressure sensitive adhesive resistor R4, is a voltage generated through voltagedivision of the pressure sensitive adhesive resistor R3 and the pressure sensitiveadhesive resistor R4; and the third voltage signal Vp13, that is, the voltage on thepressure sensitive adhesive resistor R6, is a voltage generated through voltage divisionof the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesiveresistor R6. In a case that the pressure sensor is in a high-temperature environment fora long time, the resistivities of the pressure sensitive adhesive resistor R1, the pressuresensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, the pressuresensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and thepressure sensitive adhesive resistor R6 increase as the ambient temperature rises. Whena user finger that has a temperature lower than the ambient temperature presses thepressure sensor, as shown in FIG. 4, because the pressure sensitive adhesive resistor R1,the pressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistorR5 are closer to the user finger than the pressure sensitive adhesive resistor R2, thepressure sensitive adhesive resistor R4, and the pressure sensitive adhesive resistor R6,temperatures of the pressure sensitive adhesive resistor R1, the pressure sensitiveadhesive resistor R3, and the pressure sensitive adhesive resistor R5 are lower thantemperatures of the pressure sensitive adhesive resistor R2, the pressure sensitiveadhesive resistor R4, and the pressure sensitive adhesive resistor R6, and resistivitiesof the pressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistorR3, and the pressure sensitive adhesive resistor R5 are lower than resistivities of thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R4, andthe pressure sensitive adhesive resistor R6. The pressure sensitive adhesive resistor R1,the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3,the pressure sensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5,and the pressure sensitive adhesive resistor R6 are affected by the temperature effect,so that voltages generated due to voltage division of the pressure sensitive adhesiveresistor R1, the pressure sensitive adhesive resistor R3, and the pressure sensitiveadhesive resistor R5 decrease, and voltages generated due to the voltage division of thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R4, andthe pressure sensitive adhesive resistor R6 increase.

[0024] In addition, a distance between the pressure sensitive adhesive resistor R5and the pressure sensitive adhesive resistor R1 and a distance between the pressuresensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R3 are lessthan a preset threshold, and a distance between the pressure sensitive adhesive resistorR6 and the pressure sensitive adhesive resistor R2 and a distance between the pressuresensitive adhesive resistor R6 and the pressure sensitive adhesive resistor R4 are lessthan the preset threshold. In this case, it may be considered that the temperature of thepressure sensitive adhesive resistor R5 keeps consistent with the temperatures of thepressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistor R3under any condition, and the temperature of the pressure sensitive adhesive resistor R6keeps consistent with the temperatures of the pressure sensitive adhesive resistor R2and the pressure sensitive adhesive resistor R4 under any condition. Therefore, underthe influence of the temperature effect, the decrements of the voltages generated due tothe voltage division of the pressure sensitive adhesive resistor R1, the pressure sensitiveadhesive resistor R3, and the pressure sensitive adhesive resistor R5 are equal; andincrements of the voltages generated due to the voltage division of the pressure sensitiveadhesive resistor R2, the pressure sensitive adhesive resistor R4, and the pressuresensitive adhesive resistor R6 are equal. The preset threshold may be determined basedon volume or the like of the pressure sensitive adhesive resistor, which is not limited inthis embodiment of this application.

[0025] In this case, the voltage signal output by the first Wheatstone bridge is ΔU1= Vp11 - Vp13. Through the temperature-effect-induced increment of the voltagegenerated due to the voltage division of the pressure sensitive adhesive resistor R6, the temperature-effect-induced increment of the voltage generated due to the voltagedivision of the pressure sensitive adhesive resistor R2 is removed, so that ΔU1 includesonly the electrical signal generated by the first Wheatstone bridge under pressure. Thevoltage signal output by the second Wheatstone bridge is ΔU2 = Vp12 - Vp13.Through the temperature-effect-induced increment of the voltage generated due to thevoltage division of the pressure sensitive adhesive resistor R6, the temperature-effectinduced increment of the voltage generated due to the voltage division of the pressuresensitive adhesive resistor R4 is removed, so that ΔU2 includes only the electricalsignal generated by the second Wheatstone bridge under pressure. In this way, thevoltage signal finally output by the pressure sensor, ΔU = ΔU1 + ΔU2, is only anelectrical signal converted by the pressure sensor from the pressure received.

[0026] FIG. 4 is a schematic diagram of another composition structure of a pressuresensor according to an embodiment of this application. As shown in FIG. 4, the pressuresensor in this embodiment of this application includes a flexible printed circuit board110 and multiple pressure sensitive adhesive resistors. The multiple pressure sensitiveadhesive resistors include a pressure sensitive adhesive resistor R1, a pressure sensitiveadhesive resistor R2, a pressure sensitive adhesive resistor R3, a pressure sensitiveadhesive resistor R4, a pressure sensitive adhesive resistor R5, and a pressure sensitiveadhesive resistor R6. The flexible printed circuit board 110 includes a first surface Aand a second surface B that are opposite each other. The pressure sensitive adhesiveresistor R1, the pressure sensitive adhesive resistor R3, and the pressure sensitiveadhesive resistor R5 are disposed on the first surface A, and the pressure sensitiveadhesive resistor R2, the pressure sensitive adhesive resistor R4, and the pressuresensitive adhesive resistor R6 are disposed on the second surface B. The flexible printedcircuit board 110 is further provided with through holes that allow the first surface A tocommunicate with the second surface B. The through holes include a first through holeD and a second through hole E. The first through hole D is at least partially covered bythe pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistorR2, and the second through hole E is at least partially covered by the pressure sensitiveadhesive resistor R3 and the pressure sensitive adhesive resistor R4. The pressuresensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, the pressuresensitive adhesive resistor R5, and the pressure sensitive adhesive resistor R6 areelectrically connected to form a first Wheatstone bridge, and the pressure sensitiveadhesive resistor R3, the pressure sensitive adhesive resistor R4, the pressure sensitiveadhesive resistor R5, and the pressure sensitive adhesive resistor R6 are electricallyconnected to form a second Wheatstone bridge. The Wheatstone bridge in the pressuresensor in this embodiment works in the same way as the Wheatstone bridge in thepressure sensor in FIG. 1. Therefore, details are not described herein again.

[0027] Based on a same technical concept, an embodiment of this applicationfurther provides an electronic device. The electronic device includes the pressure sensorin the foregoing embodiments. The electronic device may be at least one of a mobilephone, a tablet computer, an in-vehicle computer, a wearable device, an intelligent robot,and the like. A type of the electronic device is not limited in this embodiment of thisapplication. As shown in FIG. 3, in the electronic device, the pressure sensor is fastenedinside a device housing 210 as a hidden key. In some optional examples, the devicehousing 210 is a metal housing, and the pressure sensor is fastened inside the devicehousing 210 by using a double-sided adhesive 220.

[0028] In the electronic device according to this embodiment of this application,multiple pressure sensitive adhesive resistors are disposed on a flexible printed circuitboard. The multiple pressure sensitive adhesive resistors include a pressure sensitiveadhesive resistor R1, a pressure sensitive adhesive resistor R2, a pressure sensitiveadhesive resistor R3, a pressure sensitive adhesive resistor R4, a pressure sensitiveadhesive resistor R5, and a pressure sensitive adhesive resistor R6, and the flexibleprinted circuit board includes a first surface and a second surface that are opposite eachother. The pressure sensitive adhesive resistor R1, the pressure sensitive adhesiveresistor R3, and the pressure sensitive adhesive resistor R5 are disposed on the firstsurface, and the pressure sensitive adhesive resistor R2, the pressure sensitive adhesiveresistor R4, and the pressure sensitive adhesive resistor R6 are disposed on the secondsurface. The flexible printed circuit board is further provided with a through hole thatallows the first surface to communicate with the second surface, and the through holeis at least partially covered by the pressure sensitive adhesive resistor R1, the pressuresensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, and thepressure sensitive adhesive resistor R4. The pressure sensitive adhesive resistor R1, thepressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R5, andthe pressure sensitive adhesive resistor R6 are electrically connected to form a firstWheatstone bridge, and the pressure sensitive adhesive resistor R3, the pressuresensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and thepressure sensitive adhesive resistor R6 are electrically connected to form a secondWheatstone bridge. Voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6is used to compensate for voltage signals resulting from the temperature effect on thepressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, thepressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R4,so that a voltage signal output by the pressure sensor includes only the voltage signalgenerated by the pressure action, thereby eliminating the impact of temperature on thevoltage signal output by the pressure sensor, and implementing temperaturecompensation for the pressure sensor. This can guarantee measurement accuracy of thepressure sensor in a high or low temperature environment, and resolve problems suchas false alarm or release delay of the pressure sensor caused by the temperature effect.

[0029] It should be noted that, in this specification, the terms "include", "comprise",or any of their variants are intended to cover a non-exclusive inclusion, so that a process,a method, an article, or an apparatus that includes a series of elements not only includesthose elements but also includes other elements that are not expressly listed, or furtherincludes elements inherent to such a process, method, article, or apparatus. In absenceof more constraints, an element preceded by "includes a..." does not preclude theexistence of other identical elements in the process, method, article, or apparatus thatincludes the element.

[0030] According to the description of the foregoing implementations, personsskilled in the art can clearly understand that the method in the foregoing embodimentsmay be implemented by software in addition to a necessary universal hardware platformor by hardware only. In most cases, the former is a more preferred implementation.Based on such an understanding, the technical solutions of this application essentially,or the part contributing to the prior art may be implemented in a form of a softwareproduct. The software product is stored in a storage medium (for example, ROM / RAM,a magnetic disk, or an optical disc), and includes several instructions for instructing aterminal (which may be a mobile phone, a computer, a server, an air conditioner, anetwork device, or the like) to perform the method described in the embodiments ofthis application.

[0031] The embodiments of this application are described above with reference tothe accompanying drawings, but this application is not limited to the foregoingimplementations. The foregoing implementations are only illustrative rather thanrestrictive. Inspired by this application, persons of ordinary skill in the art can stillderive many variations without departing from the essence of this application and theprotection scope of the claims. All these variations shall fall within the protection ofthis application.

Claims

1. A pressure sensor, comprising a flexible printed circuit board and multiple pressure sensitive adhesive resistors, wherein the multiple pressure sensitive adhesive resistors comprise a pressure sensitive adhesive resistor R1, a pressure sensitive adhesive resistor R2, a pressure sensitive adhesive resistor R3, a pressure sensitive adhesive resistor R4, a pressure sensitive adhesive resistor R5, and a pressure sensitive adhesive resistor R6; the flexible printed circuit board comprises a first surface and a second surface that are opposite each other; the pressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R5 are disposed on the first surface, and the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R4, and the pressure sensitive adhesive resistor R6 are disposed on the second surface; the flexible printed circuit board is provided with a through hole that allows the first surface to communicate with the second surface, and the through hole is at least partially covered by the pressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R3, and the pressure sensitive adhesive resistor R4; and the pressure sensitive adhesive resistor R1, the pressure sensitive adhesive resistor R2, the pressure sensitive adhesive resistor R5, and the pressure sensitive adhesive resistor R6 are electrically connected to form a first Wheatstone bridge, and the pressure sensitive adhesive resistor R3, the pressure sensitive adhesive resistor R4, the pressure sensitive adhesive resistor R5, and the pressure sensitive adhesive resistor R6 are electrically connected to form a second Wheatstone bridge.

2. The pressure sensor according to claim 1, wherein a ratio of the pressure sensitive adhesive resistor R1 to the pressure sensitive adhesive resistor R2, a ratio of the pressure sensitive adhesive resistor R3 to the pressure sensitive adhesive resistor R4, and a ratio of the pressure sensitive adhesive resistor R5 to the pressure sensitive adhesive resistor R6 are equal.

3. The pressure sensor according to claim 2, wherein the pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistor R2 are electrically connected, and a first voltage signal is generated between the pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistor R2; the pressure sensitive adhesive resistor R3 and the pressure sensitive adhesive resistor R4 are electrically connected, and a second voltage signal is generated between the pressure sensitive adhesive resistor R3 and the pressure sensitive adhesive resistor R4; the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6 are electrically connected, and a third voltage signal is generated between the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R6; and a signal output by the first Wheatstone bridge is a difference between the first voltage signal and the third voltage signal; a signal output by the second Wheatstone bridge is a difference between the second voltage signal and the third voltage signal; and a signal output by the pressure sensor is a sum of the signal output by the first Wheatstone bridge and the signal output by the second Wheatstone bridge.

4. The pressure sensor according to any one of claims 1 to 3, wherein a distance between the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R1 and a distance between the pressure sensitive adhesive resistor R5 and the pressure sensitive adhesive resistor R3 are less than a preset threshold, so that temperature of the pressure sensitive adhesive resistor R5 is consistent with temperature of the pressure sensitive adhesive resistor R1 and temperature of the pressure sensitive adhesive resistor R3; and a distance between the pressure sensitive adhesive resistor R6 and the pressure sensitive adhesive resistor R2 and a distance between the pressure sensitive adhesive resistor R6 and the pressure sensitive adhesive resistor R4 are less than the preset threshold, so that temperature of the pressure sensitive adhesive resistor R6 is consistent with temperature of the pressure sensitive adhesive resistor R2 and temperature of the pressure sensitive adhesive resistor R4.

5. The pressure sensor according to claim 4, wherein the through hole comprises a first through hole and a second through hole, the first through hole is at least partially covered by the pressure sensitive adhesive resistor R1 and the pressure sensitive adhesive resistor R2, and the second through hole is at least partially covered by the pressure sensitive adhesive resistor R3 and the pressure sensitive adhesive resistor R4.

6. An electronic device, comprising the pressure sensor according to any one of claims 1 to 5, wherein the pressure sensor is fastened inside a device housing as a hidden key.

7. The electronic device according to claim 6, wherein the device housing is a metal housing, and the pressure sensor is fastened inside the device housing by using a double-sided adhesive.

8. The electronic device according to claim 7, wherein the electronic device comprises at least one of the following: a mobile phone, a tablet computer, an in-vehicle computer, a wearable device, and an intelligent robot.