CN108540119B - Pressure sensing button device and pressure sensing button measuring circuit - Google Patents
Pressure sensing button device and pressure sensing button measuring circuit Download PDFInfo
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- CN108540119B CN108540119B CN201710117805.8A CN201710117805A CN108540119B CN 108540119 B CN108540119 B CN 108540119B CN 201710117805 A CN201710117805 A CN 201710117805A CN 108540119 B CN108540119 B CN 108540119B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/96—Touch switches
- H03K17/9645—Resistive touch switches
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
- H03K2217/96—Touch switches
- H03K2217/96015—Constructional details for touch switches
- H03K2217/96023—Details of electro-mechanic connections between different elements, e.g.: sensing plate and integrated circuit containing electronics
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Abstract
A pressure sensing key device provided with a Wheatstone circuit and a pressure sensing key measuring circuit, wherein the pressure sensing key device comprises a panel bearing pressure; a sensing plate coupled to the faceplate to sense pressure, the sensing plate comprising a substrate having two opposing first and second surfaces and a Wheatstone circuit disposed on the first and second surfaces. The pressure sensing button measuring circuit includes: the pressure sensing key device; a differential operation circuit which takes the endpoint signal of the Wheatstone circuit in the pressure induction key device as an input signal; a comparator circuit that takes an output signal of the differential operation circuit as an input signal; and a latch circuit which takes an output signal of the comparator circuit as an input signal. The pressure sensing key device and the measuring circuit are simple to manufacture and low in cost, and the problem that the structure and the circuit of the pressure sensing device in the prior art are complex is solved.
Description
Technical Field
The invention mainly relates to the technical field of pressure sensing keys, in particular to a pressure sensing key device and a measuring circuit with the same.
Background
The forced induction button is based on the novel button of forced induction technique, adopts the forced induction structure to replace mechanical button structure, can turn into control signal with applying the power on the forced induction panel to realize corresponding control function. Compared with a mechanical key, the pressure sensing key has the advantages of high sensitivity, long service life, small occupied area and the like, can replace the original mechanical key in a plurality of fields, and provides a richer man-machine interaction mode for a plurality of input devices.
The existing types of pressure-sensitive keys widely used include resistance strain gauge type, capacitance-sensitive type, piezoelectric ceramic type, inductance type, etc., but these types of pressure-sensitive keys have different defects, such as strict structural requirements or complex circuit design, etc. For example, the resistance strain type pressure sensing key needs to bond a resistance strain gauge in a specific sensing structure and match with a specific circuit structure, when the sensing structure is subjected to a certain external force, the resistance strain gauge can convert the resistance strain gauge into an electric signal through the resistance of the strain gauge, and meanwhile, the resistance strain type pressure sensing key also has the defects of incapability of long-time pressing, low sensitivity, poor durability and the like; the typical capacitive sensor is composed of an upper electrode, a lower electrode, an insulator and a substrate, pressure information is obtained by detecting the change of the upper electrode and the lower electrode through an IC, the capacitive sensor is only suitable for a thin panel and has higher requirement on processing precision, if the capacitive sensor is used for a key of a metal panel, the sensitivity is very low, and the inductive pressure-sensitive key also has the defects of incapability of long-time pressing, poor anti-falling performance and the like; the piezoelectric ceramic type keys achieve the health-care effect by utilizing the transient voltage generated by pressing, but need high-temperature lamination, are only suitable for small panels and have high cost.
Therefore, a pressure sensing key and a corresponding measuring circuit with simple structure, high sensitivity, long press time, high drop resistance coefficient and low production cost are needed to overcome the defects in the prior art.
Disclosure of Invention
The invention aims to provide a pressure sensing key device and a pressure sensing key measuring circuit, which solve the problem that the structure and the circuit of the pressure sensing device in the prior art are complex, and embody the technical advantages of thick panel thickness, high sensitivity, capability of limiting key areas, long pressing and the like in the field of metal panel keys. Forced induction button device with wheatstone expert's circuit includes:
a panel subjected to pressure;
a sensing plate coupled to the faceplate to sense pressure, the sensing plate comprising a substrate having two opposing first and second surfaces and a Wheatstone circuit disposed on the first and second surfaces.
According to one aspect of the invention, the panel is a metal plate, a glass plate, a plastic plate or an aluminum alloy plate.
According to one aspect of the invention, the substrate having two opposite first and second surfaces is made of any one or more of PCB, FPC, PET.
According to one aspect of the invention, the wheatstone circuit comprises at least 8 resistors, wherein at least 4 resistors are located on the first surface and at least 4 resistors are located on the second surface.
According to one aspect of the invention, the resistors forming the wheatstone circuit are printed strain sensitive resistors having a dilatant effect.
According to one aspect of the present invention, of the at least 4 resistors on the first surface and the at least 4 resistors on the second surface, a first strain sensing resistor on the first surface and a second strain sensing resistor on the second surface are connected in series and connected to a power supply and form a first half-bridge circuit, a third strain sensing resistor on the first surface and a fourth strain sensing resistor on the second surface are connected in series and connected to the power supply and ground to form a second half-bridge circuit, a fifth strain sensing resistor on the first surface and a sixth strain sensing resistor on the second surface are connected in series and connected to the power supply and form a third half-bridge circuit, and a seventh strain sensing resistor on the first surface and an eighth strain sensing resistor on the second surface are connected in series and connected to the power supply and ground to form a fourth half-bridge circuit.
According to one aspect of the invention, the two resistors forming the first half-bridge circuit are overlapped or adjacently placed, the two resistors forming the second half-bridge circuit are overlapped or adjacently placed, the two resistors forming the third half-bridge circuit are overlapped or adjacently placed, and the two resistors forming the fourth half-bridge circuit are overlapped or adjacently placed; the first half-bridge circuit with the second half-bridge circuit is adjacent to be placed, the first half-bridge circuit with the third half-bridge circuit is placed at a distance away, the second half-bridge circuit with the fourth half-bridge circuit is placed at a distance away.
According to one aspect of the invention, the first half-bridge circuit and the second half-bridge circuit constitute a first wheatstone bridge circuit, the first half-bridge circuit and the third half-bridge circuit constitute a second wheatstone bridge circuit, and the second half-bridge circuit and the fourth half-bridge circuit constitute a third wheatstone bridge circuit.
According to one aspect of the invention, the method further comprises the following steps: and the connecting material is used for connecting the panel bearing the pressure and the induction plate and is any one or combination of two-sided adhesive, UV (ultraviolet) adhesive, AB adhesive, foam cotton adhesive or silica gel.
Correspondingly, the invention also provides a measuring circuit comprising the pressure sensing key, and specifically, the pressure sensing key measuring circuit comprises:
the pressure sensing key device;
a differential operation circuit which takes the endpoint signal of the Wheatstone circuit in the pressure induction key device as an input signal;
a comparator circuit that takes an output signal of the differential operation circuit as an input signal; and
and a latch circuit having an output signal of the comparator circuit as an input signal.
According to one aspect of the present invention, the end point signal of the wheatstone circuit in the pressure-sensitive key device comprises: a first center signal at a termination point between the first and second strain sensitive resistors, a second center signal at a termination point between the third and fourth strain sensitive resistors, a first edge signal at a termination point between the fifth and sixth strain sensitive resistors, and a second edge signal at a termination point between the seventh and eighth strain sensitive resistors.
According to one aspect of the present invention, the differential operation circuit includes at least a first differential operation circuit and a second differential operation circuit that can perform ac-coupled amplification, wherein the first center signal and the second center signal are respectively connected to positive-phase and negative-phase input terminals of the first differential operation circuit of the measurement circuit, and the first center signal and the first edge signal are respectively connected to positive-phase and negative-phase input terminals of the second differential operation circuit of the measurement circuit.
According to one of the aspects of the present invention, the output terminal of the first differential operation circuit and the output terminal of the second differential operation circuit are respectively connected to the input terminal front end of the first comparator circuit 4.
According to one aspect of the present invention, the differential operation circuit includes at least a third differential operation circuit and a fourth differential operation circuit that can perform ac-coupled amplification, wherein the second center signal and the first center signal are connected to forward and reverse input terminals of the third differential operation circuit of the measurement circuit, respectively, and the second center signal and the second edge signal are connected to forward and reverse input terminals of the fourth differential operation circuit of the measurement circuit, respectively.
According to one of the aspects of the present invention, an output terminal of the third differential operation circuit and an output terminal of the fourth differential operation circuit are connected to a non-inverting and inverting input terminals of the second comparator circuit, respectively.
According to one aspect of the present invention, an output signal of the first comparison circuit is taken as an input signal of the S terminal of the RS latch circuit, and an output signal of the second comparison circuit is taken as an input signal of the R terminal of the RS latch circuit.
Compared with the prior art, the invention has the following advantages:
firstly, the Wheatstone circuit is used as the main component of the pressure sensing unit, the structure of the pressure sensing key device is greatly simplified, only the panel directly pressed by pressure and the sensing plate which can enable the resistor to be molded on the surface are connected through the connecting material, and the pressure sensing key device has the advantages of simple circuit structure and convenience in assembly.
Secondly, the invention slightly deforms the panel by applying force to the specific position of the panel of the pressure sensing key device, so as to change the resistance value of the sensing resistor, thereby changing the endpoint signal of the Wheatstone circuit, further judging the actions of pressing, lifting hands, long pressing and the like of a user through the measuring circuit, realizing various pressure sensing key functions, and being applicable to various fields.
Finally, the effective key area can be limited according to actual needs by adjusting the resistor arrangement position in the Wheatstone circuit of the pressure sensing device, and meanwhile, the measuring circuit is only composed of a small number of discrete components, digital operation processing of an analog-to-digital conversion chip and a processor is not needed, and the design is greatly simplified.
Drawings
Fig. 1(a) is a schematic structural diagram of a pressure-sensitive key device 100 according to the present invention;
fig. 1(b) is a circuit diagram of the measurement circuit 40 with the pressure-sensitive key device 100 in fig. 1 (a);
FIG. 2 is a circuit diagram of a Wheatstone bridge circuit in the pressure-sensitive key device 100 in FIG. 1 (a);
FIG. 3 is a circuit diagram of a first differential operator circuit 42 in the measurement circuit 40 of FIG. 1 (b);
fig. 4 is a circuit diagram of a second differential operation circuit 43 in the measurement circuit 40 in fig. 1 (b);
FIG. 5 is a circuit diagram of a third differential operation circuit 44 in the measurement circuit 40 in FIG. 1 (b);
fig. 6 is a circuit diagram of a fourth differential operation circuit 45 in the measurement circuit 40 in fig. 1 (b);
FIG. 7 is a circuit diagram of the first comparator circuit 46 in the measurement circuit 40 of FIG. 1 (b);
FIG. 8 is a circuit diagram of a second comparator circuit 47 in the measurement circuit 40 in FIG. 1 (b);
FIG. 9 is a circuit diagram of an RS latch circuit in the measurement circuit 40 in FIG. 1 (b);
fig. 10 is a schematic structural diagram of a pressure-sensitive key device 100 according to another embodiment of the present invention;
fig. 11 is a schematic structural diagram of a pressure-sensitive key device 100 according to another embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a pressure sensing key device with a Wheatstone circuit and a measuring circuit with the pressure sensing key device, and aims to solve the problem that the pressure sensing device in the prior art is complex in structure and circuit, can be suitable for various panels with different thicknesses, can be particularly well applied to metal panels, and has the technical advantages of high sensitivity, key area limitation, long-time pressing and the like.
The pressure-sensitive key device 100 and the measurement circuit 40 having the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1(a) is a schematic structural diagram of a pressure-sensitive key device of the present invention. Referring to fig. 1(a), the pressure-sensitive key device 100 includes a panel 10 for receiving pressure and a sensing plate 30.
The panel 10 is used for a practitioner to apply pressure and transmit the pressure to the sensing plate 30; preferably, the panel 10 is made of a rigid material, such as a metal plate, a glass plate, a plastic plate, an aluminum alloy plate, or other rigid materials, and the deformation amount caused by the stress is much smaller than the distance between the panel 10 and the sensing plate 30, so as to prevent the panel 10 from being unable to recover after deformation and unable to sense the pressure accurately.
The sensing plate member 30 includes a substrate having two opposite first and second surfaces and a wheatstone circuit disposed on the first and second surfaces, and the substrate having two opposite first and second surfaces is formed of any one or more of PCB, FPC, and PET. Preferably, in this embodiment, the pressure-sensitive key device 100 further includes a connecting material 20, where the connecting material 20 is any one or a combination of two or more of a double-sided adhesive tape, a UV adhesive tape, an AB adhesive tape, a foam adhesive tape, or a silicone adhesive, and is used to connect and fix the panel 10 and the sensing panel 30. In other embodiments, the panel 10 and the induction panel 30 can be connected in other manners, for example, a snap fit is used at two ends of the panel 10 and the induction panel 30 or the panel 10 and the induction panel 30 can be fixed by a mortise and tenon structure, any technique and method for connecting the panel 10 and the induction panel 30 can be used in the present invention, and the above examples are only used for explaining and illustrating the present invention, and should not be construed as limiting the present invention.
Referring to fig. 1(a), the sensing panel 30 has a first surface 31 and a second surface 32 opposite to each other, and the first surface 31 of the sensing panel 30 is connected to the panel 10 through the connecting material 20. The Wheatstone circuit is arranged on the first and second surfaces of the substrate, the Wheatstone circuit comprises at least 8 resistors, wherein at least 4 resistors are arranged on the first surface, and at least 4 resistors are arranged on the second surface. In this embodiment, a wheatstone circuit constructed by 8 resistors is taken as an example for description, and in other embodiments, the number of resistors constituting the wheatstone circuit may be 10, 12, 14 or more, and will not be described herein again.
In the present embodiment, a first strain sensing resistor R is disposed on a first local area 33 on the first surface 31 of the sensing plate 301And a third strain sensitive resistor R3The first strain sensing resistor R1And a third strain sensitive resistor R3Placing the two adjacent plates; a second strain-sensitive resistor R is arranged on a second partial area 34 of the second surface 32, which corresponds directly to the first partial area 33 on the first surface 312And a fourth strain sensitive resistor R4Said second strain sensitive resistor R2And a fourth strain sensitive resistor R4Placing the two adjacent plates; a fifth strain-sensitive resistor R is arranged in a third partial region 35 at a distance from the first partial region 33 on the first surface 315A sixth strain sensitive resistor R is arranged in a fourth partial area 36 at a distance from the second partial area 34 on the second surface 326(ii) a A seventh strain-sensitive resistor R is arranged in a fifth partial region 37 at a distance from the first partial region 33 on the first surface 317An eighth strain sensitive resistor R is arranged in a sixth partial area 38 at a distance from the second partial area 34 on the second surface 328。
Preferably, the key region 11 in the present embodiment is located on the panel 11 at a position corresponding to the first partial region 33, and more preferably, the case region 11 is located above the first partial region 33 and covers the first partial region 33, and does not cover the third partial region 35 and the fifth partial region 37. In practical application, the size and position of the key region 11 can be adjusted within a certain range by adjusting the placement position of the strain sensing resistor and the parameters of the measuring circuit in the pressure sensing key device.
In the present embodiment, the first to eighth strain sensing resistors are strain sensing resistors printed on the surface of the sensing plate 30; in other embodiments, the first to eighth strain-sensing resistors may be disposed on the surface of the sensing board 30 by other methods, such as welding, electroplating, vapor deposition, etc.
FIG. 2 is a Wheatstone diagram of the pressure-sensitive key device in FIG. 1A bridge circuit. Referring to fig. 2, first and second strain sensitive resistors R1And R2A power supply connected in series and forming a first half bridge circuit, a third and a fourth strain induction resistor R3And R4A second half-bridge circuit, a fifth strain-sensing resistor R and a sixth strain-sensing resistor R are connected in series and connected with a power supply and the ground to form5And R6A third half-bridge circuit, a seventh and an eighth strain-sensing resistor R connected in series and connected to a power supply7And R8A fourth half-bridge circuit is formed by connecting a power supply and ground in series. Wherein the first and second strain sensitive resistors R1And R2A third and a fourth strain sensitive resistor R3And R4Forming a first Wheatstone bridge circuit; first and second strain sensitive resistors R1And R2Fifth and sixth strain sensitive resistors R5And R6Forming a second Wheatstone bridge circuit; third and fourth strain sensitive resistors R3And R4Seventh and eighth strain sensitive resistors R7And R8Forming a third wheatstone bridge circuit. Wherein the first and second strain sensitive resistors R1And R2Are the first center signal IN SIG1, the third and fourth strain sensitive resistors R3And R4The second central signal IN _ SIG2, the fifth and sixth strain-sensing resistors R5And R6The terminals therebetween are the first edge signal OUT _ SIG1, the seventh and eighth strain-sensing resistors R7And R8And the endpoint in between is the second edge signal OUT SIG 2.
Fig. 1(b) is a circuit diagram of a measuring circuit 40 having the pressure-sensitive key device 100 in fig. 1(a), the measuring circuit 40 includes the pressure-sensitive key device 100 in fig. 1(a), a first differential operation circuit 42 (shown in fig. 3), a second differential operation circuit 43 (shown in fig. 4), a third differential operation circuit 44 (shown in fig. 5) and a fourth differential operation circuit 45 (shown in fig. 6) which use an end signal of a wheatstone circuit in the pressure-sensitive key device as an input signal, a first comparator circuit 46 (shown in fig. 7) and a second comparator circuit 47 (shown in fig. 8) which use an output signal of the differential operation circuit as an input signal, and a latch circuit 48 (shown in fig. 9) which uses an output signal of the comparator circuit as an input signal. The measurement circuit 40 will be described in detail below with reference to the drawings.
First, the principle of the pressing operation detected by the measuring circuit 40 in the present invention will be described in detail with reference to an embodiment of the present invention.
Referring to fig. 3, the first and second center signals IN _ SIG1 and IN _ SIG2 are connected to the positive and negative input terminals front ends, respectively, of the first differential operation circuit 42 of the measurement circuit 40. Referring to fig. 4, the first center signal IN _ SIG1 and the first edge signal OUT _ SIG1 are connected to the positive and negative input terminals of the second differential operation circuit 43 of the measurement circuit 40, respectively. The voltages at the non-inverting input terminal and the inverting input terminal of the first differential operation circuit 42 are first voltages u1And a second voltage u2Flows through the second capacitor C2And a first resistor R11Respectively is iC1And iR1Output voltage of u(SIG A)(ii) a The voltages at the non-inverting input terminal and the inverting input terminal of the second differential operation circuit 43 are respectively the third voltage u3And a fourth voltage u4Through a third capacitor C3And a fourth resistor R14Respectively is iC2And iR2Output voltage of u(SIG B)。
Current i of second center signal IN _ SIG2 when no pressure is applied to key location 11 on panel 102Is a direct current, so the first capacitor C1And a first resistor R11Current i ofC1And iR1Are all 0, output voltage u(SIGA)A first voltage u1Equal to the voltage u of the first center signal IN _ SIG1, i.e., u(SIGA)＝u1＝u(IN_SIG1)(ii) a Similarly, the current i of the first edge signal OUT _ SIG11Is also a direct current, so the second capacitor C2And a second resistor R12Current i ofC2And iR2Are all 0, output voltage u(SIGB)A third voltage u3U equal to the voltage u of the first center signal IN _ SIG1(SIGB)＝u3＝u(IN_SIG1)。
Referring to fig. 7, an output terminal SIGA of the first differential operation circuit 42 and an output terminal SIGB of the second differential operation circuit 43 are respectively connected to the front ends of input terminals of the first comparator circuit 46, and voltages of a forward input terminal and a reverse input terminal of the first comparator circuit 46 are respectively u5And u6According to the working principle of the comparator circuit:
u5-u6
＝u(SIGA)-0.2V-u(SIGB)
＝u(IN_SIG1)-0.2V-u(IN_SIG1)
＝-0.2V
that is, when no pressure is applied to the panel 10, the first press comparator 46 outputs a low level.
When a force is applied to the sensing panel at the key position 11, the relationship between the strain sensitive resistor and the curvature radius of the first surface 31 and the second surface 32 of the sensing plate 30 is known as follows: three induction resistors R for sensing the first surface of the plate1、R3、R5Becomes smaller, and R of the second surface becomes smaller2、R4、R6The resistance values of (2) are all increased. First to fourth strain sensitive resistors R in the present invention due to difference between the resistor discharge position and the pressing position1、R2、R3And R4Has a resistance variation amount larger than that of the fifth and sixth strain sensitive resistors R5And R6The amount of change in (c). At this time, the current i of the second center signal(IN_SIG2)For AC current, flows through the first capacitor C1And a first resistor R1Current i ofC1And iR1The following relationship is satisfied:
iC1＝C2*du(IN_SIG2)/dt；
iR1＝[u2-u(SIGA)]/R11。
according to the principle of virtual shortness, u2＝u3＝u(IN_SIG1)Thus:
iR1＝[u(IN_SIG1)-u(SIGA)]/R11；
and due to C2And R11In a serial relationship, i.e. iC1＝iR1Thus:
C2*du(IN_SIG2)/dt＝[u(IN_SIG1)-u(SIGA)]/R11；
that is to say that the first and second electrodes,
u(SIGA)＝u(IN_SIG1)-R11*C2*du(IN_SIG2)/dt。
similarly, the voltage u at the output terminal of the second sensing circuit 43 can be obtained(SIGB)Comprises the following steps:
u(SIGB)＝u(IN_SIG1)-R14*C3*du(OUT_SIG1)/dt；
at this time, the first comparator circuit 46 output voltage satisfies the following relationship:
u5-u6
＝u(SIGA)-0.2V-u(SIGB)
＝{[u(IN_SIG1)-R11*C2*du(IN_SIG2)/dt]-0.2v}-[u(IN_SIG1)-R14*C3*du(OUT_SIG1)/dt]
＝R14*C3*du(OUT_SIG1)/dt-R11*C2*du(IN_SIG2)/dt-0.2V。
from the above, when the sensing plate 30 is pressed, the third and fifth strain sensing resistors R3And R5Is increased, fourth and sixth strain sensing resistors R4And R6Is made small, and the third and fifth strain sensitive resistors R3And R4Is greater than the fourth and sixth strain sensitive resistors R5And R6So du is(IN_SIG2)And du(OUT_SIG1)Are all negative values and | du(IN_SIG2)| is greater than | du(OUT_SIG1)L, |; by adjusting the second capacitance C2A first resistor R11A third capacitor C3And a fourth resistor R14Can make the center of the key bear a certain pressureAnd when the voltage of the output end of the comparator circuit meets the following conditions:
u5-u6
＝R14*C3*du(OUT_SIG1)/dt-R11*C2*du(IN_SIG2)/dt-0.2V＞0。
during the period after the panel 10 is pressurized and before the force application object is removed, the voltage of the first edge signal OUT _ SIG1 remains unchanged, and thus du is(OUT_SIG1)At 0, the voltage at the output of the first comparator circuit 46 satisfies:
u5-u6
＝u(SIGA)-0.2V-u(SIGB)
＝u(IN_SIG1)-0.2V-u(IN_SIG1)
＝-0.2V＜0。
when the force application object leaves, du is(IN_SIG2)And du(OUT_SIG1)Are all positive values and | du(IN_SIG2)| is greater than | du(OUT_SIG1)I, the voltage at the output of the first comparator circuit 46 satisfies:
u5-u6
＝R14*C3*du(OUT_SIG1)/dt-R11*C2*du(IN_SIG2)/dt-0.2V＜0。
based on the above analysis, the difference Δ ═ u by the comparator circuits of the above four periods5-u6As a result, it can be seen that when the output terminal EN1 of the first comparator circuit 46 is at a high level, it indicates that the panel 10 is pressed, corresponding to the pressing action; in other cases, the output terminal EN1 of the first comparator circuit 46 is at a low level, and the function of detecting the pressing operation is realized.
As described above, the principle of determining the hand-up operation for the measurement circuit of the present invention is as follows: the second center signal IN _ SIG2 and the first center signal IN _ SIG1 are connected to the positive and negative input terminals of the third differential operation circuit 44 of the measurement circuit 40, respectively, and the second center signal IN _ SIG2 and the second edge signal OUT _ SIG2 are connected to the positive and negative input terminals of the fourth differential operation circuit 45 of the measurement circuit 40, respectivelyThe positive and negative input terminals front end, the output terminal SIGC of the third differential operation circuit 44 and the output terminal SIGD of the fourth differential operation circuit 45 are connected to the positive and negative input terminals of the second comparator circuit 47 by adjusting the fifth capacitor C5A seventh resistor R17A sixth capacitor C6And a ninth resistor R19The output end EN2 of the second comparator circuit 47 outputs a low level 0 before the hand is lifted after no-press, press and press, and outputs a high level 1 during the hand-lifting.
Similarly, referring to fig. 9, the principle of the measuring circuit in the present invention for implementing long press function is as follows: an output signal EN1 of the first comparator circuit 46 is input to the S terminal of the RS latch circuit, an output signal EN2 of the second comparator circuit 47 is input to the R terminal of the RS latch circuit, and when S is 0 and R is 1, an output Q of the RS latch is 0; when S is 1 and R is 0, Q is 1; q remains unchanged when S ═ R ═ 0, at which time Q and-Q interlock; when R ═ S ═ 1, the Q value is unstable (the simultaneous presence of pressing and raising is impossible, so the case of R ═ S ═ 1 does not exist). Therefore, a Q value of 1 can be obtained when pressing and before raising the hand after pressing, and a Q value of 0 can be obtained when raising the hand and without pressing, thereby realizing the long press function. The pressure-sensitive key function can be realized by inputting a Q value and matching with a relevant feedback circuit, such as an LED, a buzzer, a motor and the like.
In practical application, the size and position of the key region 11 can be adjusted within a certain range by adjusting the placement position of the strain sensing resistor and the parameters of the measuring circuit in the pressure sensing key device. For example, referring to fig. 10, the strain-sensing resistor on the first surface 31 is moved away from the center of the key region 11 along the direction indicated by the arrow, and the size and spacing of the rest of the resistors and the parameters of the measuring circuit 40 are adjusted to implement the function of pressure-sensitive key; accordingly, referring to fig. 11, the strain sensitive resistor on the second surface 32 is moved away from the center of the key region 11 along the direction shown by the arrow, and the size and the distance of the rest of the resistors and the parameters of the measuring circuit 40 are adjusted to realize the function of the pressure-sensitive key.
The Wheatstone circuit is used as the main component of the pressure sensing unit, the structure of the pressure sensing key device is greatly simplified, only the panel directly pressed by pressure and the sensing plate which can enable the resistor to be molded on the surface are connected through the connecting material, and the pressure sensing key device has the advantages of simple circuit structure and convenience in assembly. Meanwhile, the invention slightly deforms the panel by applying force to the specific position of the panel of the pressure sensing key device, so that the resistance value of the sensing resistor is changed, the endpoint signal of the Wheatstone circuit is changed, the actions of pressing, lifting hands, long pressing and the like of a user are judged by the measuring circuit, various pressure sensing key functions can be realized, and the pressure sensing key device can be applied to various fields. In addition, the effective key area can be limited according to actual needs by adjusting the resistor arrangement position in the Wheatstone circuit of the pressure sensing device, and meanwhile, the measuring circuit is only composed of a small number of discrete components, digital operation processing of an analog-to-digital conversion chip and a processor is not needed, and the design is greatly simplified.
It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. In addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. A plurality of units or means recited in the system claims may also be implemented by one unit or means in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A pressure sensing key device with a Wheatstone circuit is characterized by comprising:
a panel (10) subject to pressure;
a sensing plate (30) coupled to the panel (10) to sense pressure, the sensing plate (30) comprising a substrate having two opposing first and second surfaces and a wheatstone circuit disposed on the first and second surfaces;
the Wheatstone circuit comprises at least 8 resistors, wherein at least 4 resistors are positioned on the first surface, and at least 4 resistors are positioned on the second surface; the resistance forming the Wheatstone circuit is a printed strain sensing resistance with a voltage variation effect;
a first strain-induced resistance (R) at the first surface of the at least 4 resistors at the first surface and at least 4 resistors at the second surface1) And a second strain sensitive resistor (R) on the second surface2) A third strain sensitive resistor (R) connected in series with the power supply and forming a first half-bridge circuit on the first surface3) And a fourth strain sensitive resistor (R) on the second surface4) A fifth strain sensitive resistor (R) on the first surface and connected in series to form a second half-bridge circuit5) And a sixth strain sensitive resistor (R) on the second surface6) A seventh strain sensitive resistor (R) connected in series to the power supply and forming a third half-bridge circuit on the first surface7) And an eighth strain sensitive resistor (R) on the second surface8) A fourth half-bridge circuit is formed by connecting a power supply in series and connecting the power supply with the ground;
first and second strain sensitive resistors (R)1And R2) A first center signal at the end point between, a third and a fourth strain sensitive resistor (R)3And R4) Second center signal at the end point in between, fifth and sixth strain sensing resistances (R)5And R6) A first edge signal at a terminal in between, seventh and eighth strain-sensing resistors (R)7And R8) A second edge signal at the end point therebetween, the differential operation circuit includes at least a first differential operation circuit, a second differential operation circuit, a third differential operation circuit and a fourth differential operation circuit capable of ac-coupled amplification, wherein,
the first center signal and the second center signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a first differential operation circuit of the measuring circuit, and the first center signal and the first edge signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a second differential operation circuit of the measuring circuit; the output end of the first differential operation circuit and the output end of the second differential operation circuit are respectively connected to the front end of the input end of the first comparator circuit;
the second center signal and the first center signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a third differential operation circuit of the measuring circuit, and the second center signal and the second edge signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a fourth differential operation circuit of the measuring circuit;
an output terminal of the third differential operation circuit and an output terminal of the fourth differential operation circuit are connected to a positive phase input terminal and an inverted phase input terminal of the second comparator circuit, respectively.
2. Pressure-sensitive key device according to claim 1, characterized in that the panel (10) is a metal, glass, plastic or aluminium alloy plate.
3. The pressure-sensitive key device of claim 1, wherein the substrate having two opposing first and second surfaces is made of any one or more of PCB, FPC, PET.
4. The pressure sensitive key device of claim 1,
the two resistors forming the first half-bridge circuit are overlapped or adjacently placed, the two resistors forming the second half-bridge circuit are overlapped or adjacently placed, the two resistors forming the third half-bridge circuit are overlapped or adjacently placed, and the two resistors forming the fourth half-bridge circuit are overlapped or adjacently placed;
the first half-bridge circuit with the second half-bridge circuit is adjacent to be placed, the first half-bridge circuit with the third half-bridge circuit is placed at a distance away, the second half-bridge circuit with the fourth half-bridge circuit is placed at a distance away.
5. The pressure sensitive key device of claim 1,
the first half-bridge circuit and the second half-bridge circuit form a first Wheatstone bridge circuit, the first half-bridge circuit and the third half-bridge circuit form a second Wheatstone bridge circuit, and the second half-bridge circuit and the fourth half-bridge circuit form a third Wheatstone bridge circuit.
6. The pressure sensitive key device of claim 1, further comprising: and the connecting material (20) is used for connecting the pressure-bearing panel (10) and the sensing plate (30), and the connecting material (20) is any one or combination of a double-sided adhesive tape, a UV (ultraviolet) adhesive tape, an AB (AB) adhesive tape, a foam cotton adhesive tape or a silica gel.
7. A pressure sensing button measurement circuit, comprising:
the pressure sensitive key device of any one of claims 1-6;
a differential operation circuit which takes the endpoint signal of the Wheatstone circuit in the pressure induction key device as an input signal; the end point signal of the Wheatstone circuit in the pressure sensing key device comprises the following components:
first and second strain sensitive resistors (R)1And R2) A first center signal at a terminal point therebetween, third and fourth strain sensitive resistors: (R3And R4) Second center signal at the end point in between, fifth and sixth strain sensing resistances (R)5And R6) A first edge signal at a terminal in between, seventh and eighth strain-sensing resistors (R)7And R8) A second edge signal at a terminal point therebetween, the differential operation circuit including at least a first differential operation circuit and a second differential operation circuit capable of ac-coupled amplification, wherein,
the first center signal and the second center signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a first differential operation circuit of the measuring circuit, and the first center signal and the first edge signal are respectively connected to the front ends of positive-phase and reverse-phase input ends of a second differential operation circuit of the measuring circuit; the output end of the first differential operation circuit and the output end of the second differential operation circuit are respectively connected to the front end of the input end of the first comparator circuit; and
and a latch circuit having an output signal of the comparator circuit as an input signal.
8. The pressure sensitive key measurement circuit of claim 7 wherein the output signal of the first comparator circuit is used as the input signal to the S terminal of the RS latch circuit and the output signal of the second comparator circuit is used as the input signal to the R terminal of the RS latch circuit.
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| CN113242965B (en) | 2018-12-20 | 2022-10-14 | 深圳纽迪瑞科技开发有限公司 | Pressure sensor and electronic terminal |
| CN110597411B (en) * | 2019-08-21 | 2021-10-29 | 维沃移动通信有限公司 | Pressure detection circuit, electronic device, and control method for pressure detection circuit |
| CN113407036A (en) * | 2020-03-16 | 2021-09-17 | 原相科技股份有限公司 | Touch keyboard |
| CN113589081A (en) * | 2021-07-30 | 2021-11-02 | 深圳市汇创达科技股份有限公司 | Control device for detecting pressure-sensitive key signal |
| CN113588079A (en) * | 2021-07-30 | 2021-11-02 | 深圳市汇创达科技股份有限公司 | Device for detecting light sensation of LED |
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