CN109668659B - Pressure sensor and pressure sensing method - Google Patents
Pressure sensor and pressure sensing method Download PDFInfo
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- CN109668659B CN109668659B CN201710962848.6A CN201710962848A CN109668659B CN 109668659 B CN109668659 B CN 109668659B CN 201710962848 A CN201710962848 A CN 201710962848A CN 109668659 B CN109668659 B CN 109668659B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
- G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
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Abstract
The invention discloses a pressure sensor, which comprises a first polar plate; a plurality of second electrode plates; the elastic body is arranged between the first polar plate and the plurality of second polar plates; a first switch, including a first end coupled to the first electrode plate, and a second end selectively coupled to a receiving end of the first electrode plate or a grounding end; and a plurality of second switches, wherein each second switch comprises a first end coupled to one of the plurality of second pole plates and a second end selectively coupled to a second pole plate receiving end, the ground end or a driving signal end.
Description
Technical Field
The present invention relates to a pressure sensor and a pressure sensing method, and more particularly, to a pressure sensor and a pressure sensing method that adjust a pressure according to a lower pressure and a capacitance.
Background
With the development of technology, touch-controlled electronic devices have been widely used by the general public. The touch electronic device can provide a function of determining a multi-stage pressing force in addition to determining an operation point touched by a user, so as to further expand the touch function of the mobile device and improve the use experience of the user.
The conventional touch device utilizes a capacitive pressure sensing method to determine the pressing force. For example, an elastic body is arranged between the two polar plates, and the pressure is judged according to the capacitance value sensed by the polar plates. When the force is applied to the plates, the distance between the two plates will change and the capacitance value sensed by the plates will also change. However, a common problem is that the change in capacitance value and the pressing force tend to have a non-linear relationship, resulting in inconsistent sensing sensitivity. Referring to fig. 1, fig. 1 is a schematic diagram illustrating a capacitance value and a lower pressure obtained in a conventional capacitive pressure sensing process. Under the condition of a certain volume of the elastic body, the thickness of the elastic body is inversely proportional to the sectional area, and the capacitance value is proportional to the sectional area of the elastic body and inversely proportional to the thickness of the elastic body. As shown in fig. 1, in the low pressure section (LP), when the lower pressure channel sharply increases, the capacitance value changes slightly. In the high pressure region (HP), the capacitance increases dramatically as the lower pressure channel increases slightly. Therefore, since the capacitance value obtained by the conventional touch device and the pressing force have a non-linear relationship, the sensitivity of the touch device corresponding to the pressing force cannot be fixed when the touch device is pressed by a user, and thus the product satisfaction of the user in using the touch device is reduced. Therefore, it is one of the objectives of the industry to provide linear signal feedback according to the pressure, so as to further improve the satisfaction of the user in using the product.
Disclosure of Invention
Therefore, in order to solve the above problems, the present invention provides a pressure sensor and a pressure sensing method that can provide a corresponding linear signal feedback according to a lower pressure so as to further improve the satisfaction of a user when using a product.
The invention provides a pressure sensor, which comprises a first polar plate; a plurality of second electrode plates; the elastic body is arranged between the first polar plate and the plurality of second polar plates; a first switch, including a first end coupled to the first electrode plate, and a second end selectively coupled to a receiving end of the first electrode plate or a grounding end; and a plurality of second switches, wherein each second switch comprises a first end coupled to one of the plurality of second pole plates and a second end selectively coupled to a second pole plate receiving end, the ground end or a driving signal end.
The invention also provides a pressure sensing method, which is suitable for a pressure sensor, wherein the pressure sensor comprises an elastic body, a first polar plate and a plurality of second polar plates, the elastic body is arranged between the first polar plate and the plurality of second polar plates, the pressure sensing method comprises the steps of setting an electrode connection configuration, and the electrode connection configuration comprises that at least one part of the plurality of second polar plates are coupled with a driving signal end and the other second polar plates are coupled with a grounding end; applying different forces to the first electrode plate, and detecting capacitance values of the first electrode plate and areas of the compressed electrodes corresponding to the different forces according to the electrode connection configuration; and storing the electrode connection configuration, the first capacitance values corresponding to different forces and the corresponding relation of the area of the compressed electrode.
Drawings
FIG. 1 is a diagram illustrating capacitance and lower pressure obtained in conventional capacitive pressure sensing.
Fig. 2 is a schematic diagram of a pressure sensor according to an embodiment of the present invention.
Fig. 3 is a partial perspective view of the pressure sensor of fig. 2.
Fig. 4 to 6 are schematic diagrams of a pressure sensing process according to an embodiment of the invention.
FIG. 7 is a diagram illustrating characteristic curves obtained under different electrode connection configurations according to an embodiment of the present invention.
Fig. 8 to 11 are schematic views illustrating a second plate according to an embodiment of the invention.
Wherein the reference numerals are as follows:
20 pressure sensor
200 first polar plate
202 elastic body
204_1～204_5、804_1～804_8、
904_1 to 904_7, 1004_1 to 1004_6 second plate
、1104_1～1104_16
206 first switch
208_1 to 208_5 second switches
210 control unit
212 drive unit
214 processing unit
216 storage unit
Gnd ground terminal
HP and LP interval
Curves L1, L2
Ra-Re second pole plate receiving end
Rx first polar plate receiving end
Tx drive signal terminal
40. 50, 60 procedures
400 to 408, 500 to 508, 600 to 614
Detailed Description
Referring to fig. 2 and 3, fig. 2 is a schematic diagram of a pressure sensor 20 according to an embodiment of the invention. Fig. 3 is a partial perspective view of the pressure sensor 20 in fig. 2. The pressure sensor 20 can be applied to various touch electronic devices, such as a tablet computer, a smart phone, a smart band, and a smart watch. The pressure sensor 20 includes a first plate 200, an elastic body 202, and second plates 204_1 to 204_ 5. The Elastic body 202 may be an Elastic three-dimensional material, and is disposed between the first electrode plate 200 and the second electrode plate 202, and can generate Elastic Deformation (Elastic Deformation) according to an external force. When an external force is applied to the first plate 200, the elastic body 202 can be elastically deformed according to the magnitude of the external force, in this case, the sectional area of the elastic body 202 will be changed, and the distance between the first plate 200 and the second plate 204 will also be changed to generate a corresponding capacitance value.
In addition, the pressure sensor 20 further includes a first switch 206, second switches 208_1 to 208_5, a control unit 210, a driving unit 212, a processing unit 214, and a storage unit 216. The first switch 206 includes a first terminal and a second terminal, wherein the first terminal of the first switch 206 is coupled to the first plate 200, and the second terminal of the first switch 206 is selectively coupled to the first plate receiving terminal Rx or the ground terminal Gnd. For example, when the second terminal of the first switch 206 is coupled to the first plate receiving terminal Rx, the processing unit 214 can receive the sensing signal through the first plate receiving terminal Rx to determine a first capacitance between the first plate 200 and the second plates 204_ 1-20 _ 5. In this case, the first capacitance may be a total capacitance related to the distance between the plates. Each second switch corresponds to a corresponding second plate, and each second switch includes a first end and a second end, wherein the first end of each second switch is coupled to the corresponding second plate, and the second end of each second switch is selectively coupled to a corresponding second plate receiving end, the ground end Gnd or the driving signal end Tx. For example, as shown in fig. 2, a first terminal of the second switch 208_1 is coupled to the second plate 204_1, and a second terminal of the second switch 208_1 can be selectively coupled to the second plate receiving terminal Ra, the ground terminal Gnd or the driving signal terminal Tx. The first terminal of the second switch 208_2 is coupled to the second plate 204_2, and the second terminal of the second switch 208_2 can be selectively coupled to the second plate receiving terminal Rb, the ground terminal Gnd or the driving signal terminal Tx, and so on. In an embodiment, when the second terminal of the first switch 206 is coupled to the ground Gnd and the second terminal of the second switch 208_1 is coupled to the second plate receiving terminal Ra, the processing unit 214 can receive the sensing signal through the second plate receiving terminal Ra to determine a second capacitance between the first plate 200 and the second plate 204_ 1. In this case, the second capacitance value may be a respective capacitance value between the second plate 204_1 and the first plate 200, and so on.
The control unit 210 is used for generating a control signal to control the operations of the first switch and the second switches 208_1 to 208_ 5. For example, according to the control signal generated by the control unit 210, the second terminal of the first switch 206 can be connected to the first plate receiving terminal Rx or the ground terminal Gnd, so as to couple the first plate 200 to the first plate receiving terminal Rx or the ground terminal Gnd. For example, according to the control signal generated by the control unit 210, the second terminals of the second switches 204_1 to 204_5 can be coupled to the corresponding second panel receiving terminals Ra to Re, the ground terminal Gnd or the driving signal terminal Tx. The driving unit 212 is coupled to the driving signal terminal Tx for generating a driving signal, and the driving signal generated by the driving unit 212 can be transmitted to the second plate coupled to the driving signal terminal Tx. The processing unit 214 is coupled to the first plate receiving terminal Rx and the second plate receiving terminals Ra to Re, and configured to receive the first sensing signal S through the first plate receiving terminal Rx during the normal operation period and accordingly determine a first capacitance C corresponding to the first force, and receive corresponding sensing signals through the first plate receiving terminal Rx and the second plate receiving terminals Ra to Re during the test period, so as to determine a corresponding relationship between the first capacitance corresponding to different forces and the area of the compressive electrode.
Further, the control unit 210 may generate corresponding control signals to control the operations of the first switch and the second switch according to the selected electrode connection configuration. For example, the electrode connection configuration may include at least a portion of the second plates 204_ 1-204 _5 coupled to the ground Gnd or in a floating state and the remaining second plates coupled to the driving signal terminal Tx. For example, assume that a first electrode connection configuration includes the second plates 204_1, 204_2, and 204_5 coupled to the driving signal terminal Tx and the second plates 204_3 and 204_4 coupled to the ground terminal Gnd. In this way, the control unit 210 can generate the corresponding control signal according to the first electrode connection configuration. As shown in fig. 2 and 3, according to the control signal, one end of the second switch 208_1 is connected to the second plate 204_1, and the other end of the second switch 208_1 is connected to the driving signal terminal Tx, so as to couple the second plate 204_1 to the driving signal terminal Tx. One end of the second switch 208_2 is connected to the second plate 204_2, and the other end of the second switch 208_2 is connected to the driving signal terminal Tx, so as to couple the second plate 204_2 to the driving signal terminal Tx. One end of the second switch 208_5 is connected to the second plate 204_5, and the other end of the second switch 208_5 is connected to the driving signal terminal Tx, so as to couple the second plate 204_5 to the driving signal terminal Tx. According to the control signal, one end of the second switches 208_3 and 208_4 is connected to the second plates 204_3 and 204_4, respectively, and the other end of the second switches 208_3 and 208_4 is coupled to the ground Gnd, respectively. In this way, the driving signal generated by the driving unit 212 is transmitted to the second plates 204_1, 204_2 and 204_ 5. At this time, the second plates 204_3 and 204_4 are coupled to the ground Gnd and do not receive the driving signal. Further, according to the control signal, one end of the first switch 206 is connected to the first pad 200, and the other end of the first switch 206 is connected to the first pad receiving terminal Rx, so as to couple the first pad 200 to the first pad receiving terminal Rx. In this case, the processing unit 214 can receive the corresponding sensing signal through the first pad receiving end Rx and determine the corresponding first capacitance value accordingly, and determine the magnitude of the external force according to the first capacitance value.
In brief, the pressure sensor 20 changes the distance between the first plate and the second plate by the elastic deformation of the elastic body 202, and then senses the corresponding capacitance value, so as to determine the pressing force of the user, and when the elastic body 202 is subjected to the pressure and generates the elastic deformation, the sectional area and the thickness of the elastic body 202 will be changed, and further change the medium between part of the second plate and the first plate 200 (i.e. the capacitance medium of part of the area is converted from air to the elastic body 202), and then change the capacitance value between the first plate 200 and all the second plates. Meanwhile, the pressure sensor 20 may generate corresponding control signals to control the operations of the first switch and the second switch according to the selected electrode connection configuration. For example, as shown in fig. 3, the cross-sectional area of the elastic body 202 covers the second plates 204_1 to 204_5, and the second plates 204_1, 204_2 and 204_5 are coupled to the driving signal terminal Tx and the second plates 204_3 and 204_4 are coupled to the ground terminal Gnd according to a first electrode connection configuration. Therefore, the pressure sensor can obtain a capacitance value corresponding to the amount of the pressing force by measuring on the first plate 200. In other words, a portion of the second plates can be coupled to the ground or switched to the floating state according to the requirement, and the rest of the second plates can be coupled to the driving unit 212 to receive the driving signal, so as to improve the problems of non-linear sensing and unstable sensitivity.
During a normal operation, the operation of the pressure sensor 20 can be summarized as a process 40, please refer to fig. 4, fig. 4 is a schematic diagram of a pressure sensing process 40 according to an embodiment of the present invention, the process 40 includes the following steps:
step 400: and starting.
Step 402: generating a control signal according to the electrode connection configuration.
Step 404: and coupling at least one second plate to the grounding end and coupling the rest second plates to the driving signal end according to the control signal.
Step 406: the sensing signal is received by the receiving end of the first electrode plate, and the corresponding capacitance value is determined according to the sensing signal.
Step 408: and (6) ending.
According to the process 40, in step 402, the control unit 210 generates corresponding control signals to control the first switch 206 and the second switches 208_ 1-208 _5 according to the selected electrode connection configuration. The selected electrode connection configuration may be a default electrode connection configuration or an electrode connection configuration selected by a user. For example, assume that the selected electrode connection configuration is a first electrode connection configuration. The first electrode connection configuration includes the second plates 204_1, 204_2, and 204_5 coupled to the driving signal terminal Tx and the second plates 204_3 and 204_4 coupled to the ground terminal Gnd. The user may notify the control unit 210 of the selected electrode connection configuration being the first electrode connection configuration through a hardware or software manner.
In step 404, at least a portion of the second plates 204_ 1-204 _5 are coupled to the ground or switched to a floating state according to the control signal, and the rest of the second plates are coupled to the driving signal terminal Tx. For example, if the selected electrode connection configuration is the first electrode connection configuration, the second plates 204_1, 204_2 and 204_5 may be respectively coupled to the driving signal terminal Tx by the connection operations of the second switches 208_1, 208_2 and 208_5 according to the control signal generated by the control unit 210. According to the control signal generated by the control unit 210, the second plates 204_3 and 204_4 can be respectively coupled to the ground Gnd through the connection operation of the second switches 208_3 and 208_ 4.
In step 406, when the user applies a force to the first plate 200, the processing unit 214 receives a sensing signal through the first plate receiving terminal Rx and determines a corresponding capacitance value accordingly. In this way, the processing unit 214 can determine the magnitude of the force currently applied by the user according to the determined magnitude of the capacitance.
On the other hand, the electrode connection configuration is selected and optimized to provide more users. During a test operation, the operation of the pressure sensor 50 can be summarized as a process 50, please refer to fig. 5, which is a schematic diagram of a pressure sensing process 50 according to an embodiment of the present invention, wherein the process 50 includes the following steps:
step 500: and starting.
Step 502: setting the electrode connection configuration.
Step 504: applying different forces to the first plate, and detecting first capacitance values and compressed electrode areas corresponding to the different forces according to the electrode connection configuration.
Step 506: the storage electrode connection configuration, the first capacitance corresponding to different forces and the corresponding relation of the area of the compression electrode.
Step 508: and (6) ending.
The pressure sensor 20 can set a plurality of different electrode connection configurations according to the process 50, and adjust the coupling state of the second switch 204 according to the electrode connection configurations to obtain the first capacitance values and the compressed electrode areas corresponding to different forces. Since the compressive electrode area is related to the amount of pressing force, the compressive electrode area can be used as a parameter related to the amount of pressing force. The process 50 obtains the corresponding relationship between the first capacitance and the area of the compressed electrode corresponding to different forces, i.e. the curve characteristic relationship between the pressing force and the capacitance between the first plate 200 and the second plates 204_ 1-204 _ 5. As the electrode connection configuration changes, the pressure sensor 20 can measure the relationship curve of the amount of pressure and the capacitance corresponding to the respective electrode connection configuration, and then select the electrode connection configuration that best meets the user's requirement to provide the user with the pressure detection operation.
According to the process 50, in step 502, the processing unit 214 first sets an electrode connection configuration, sets at least a portion of the second plates 204_ 1-204 _5 to be grounded or switched to a floating state, and couples the remaining second plates to the driving signal terminal Tx to receive the driving signal.
In step 504, the processing unit 214 instructs the control unit 210 to switch the first switch 206 and the second switches 208_1 to 208_5 according to the set electrode connection configuration to obtain corresponding capacitance values under various pressing forces and corresponding compression electrode areas (cross-sectional areas of the elastic bodies 102) under various pressing forces, so as to obtain a relationship graph of the pressing forces corresponding to the capacitance values.
In one embodiment, in step 504, regarding obtaining the corresponding capacitance values and the corresponding compressed electrode areas under different pressing forces, the processing unit 214 first transmits an electrode connection configuration to the control unit 210, the control unit 210 generates corresponding control signals according to the electrode connection configuration, connects a portion of the second plates 204_1 to 204_5 to the ground Gnd through the connection operations of the second switches 208_1 to 208_5, couples the remaining second plates to the driving signal terminal Tx, and couples the first plate 200 to the first plate receiving terminal Rx through the first switch. Therefore, when a specific pressing force is applied to the first plate 200 of the pressure sensor 20, the processing unit 214 coupled to the first plate receiving end Rx can receive the first sensing signal S at the first plate receiving end Rx and determine a first capacitance value C accordingly. At this time, the first capacitance determined by the processing unit 214 is the first capacitance corresponding to the specific pressing force. It is noted that, since at least a portion of the second plate 206 is coupled to the ground Gnd, the processing unit 214 measures the first sensing capacitance value as the capacitance value adjusted by the electrode connection configuration under the condition of applying the specific pressing force.
In addition, after the processing unit 214 determines the first capacitance value corresponding to the specific pressing force amount, the processing unit 214 instructs the control unit 210 to generate a corresponding control signal to couple the first plate 200 to the ground Gnd and couple the second plates 204_1 to 204_5 to the corresponding second plate receiving terminals, respectively. For example, the second terminal of the first switch 206 is switched from the first plate receiving terminal Rx to the ground Gnd. The second terminal of the second switch 208_1 is switched from the ground Gnd, the driving signal terminal Tx or the floating state to the second plate receiving terminal Ra. The second terminal of the second switch 208_2 is switched to the second plate receiving terminal Rb. Similarly, the second terminals of the second switches 208_3 to 208_5 are also switched to the second panel receiving terminals Rc to Re, respectively. Thus, the second electrode plates 204_1 to 204_5 are coupled to the second electrode receiving terminals Ra to Re, respectively. In this case, the processing unit 214 can receive the second sensing signals S _1 to S _5 corresponding to the second plates 204_1 to 204_5 through the second plates 204_1 to 204_5, respectively, and accordingly determine the second capacitance values C _1 to C _5 corresponding to the second plates 204_1 to 204_ 5. Then, the processing unit 214 determines a compressed second plate from the second plates 204_1 to 204_5 according to the second capacitance values C _1 to C _5 and calculates an area of a region covered by the compressed second plate as a compressed electrode area corresponding to the specific force.
Further, since the air has a smaller Permittivity (transmittance) than the elastic body 202, the second plate not in contact with the elastic body 202 will have a smaller capacitance than the second plate in contact with the elastic body 202, and thus the processing unit 214 can determine a compression electrode area (corresponding to the cross-sectional area of the elastic body 202) accordingly. Specifically, for each second plate, the processing unit 214 compares the second capacitance measured on each second plate with a predetermined capacitance, and determines that the corresponding second plate is a compressed second plate (or the corresponding second plate is in contact with the elastic body 202) when the second capacitance is greater than the predetermined capacitance. If the second capacitance value is smaller than the predetermined capacitance value, the corresponding second electrode plate is determined to be an uncompressed second electrode plate (or the corresponding second electrode plate is not in contact with the elastic body 202). The processing unit 214 sums all areas of the second plate 204 that are determined to be compressed (or in contact with the elastic body 202) to be the areas of the compressed electrodes corresponding to the specific force. That is, the processing unit 214 calculates the area of the region covered by the second plate determined to be compressed as the area of the compressed electrode corresponding to the specific force. For example, referring to fig. 3, if the second capacitance values C _1 to C _5 corresponding to the second plates 204_1 to 204_5 are all greater than the predetermined capacitance value, it is determined that the second plates 204_1 to 204_5 are all compressed second plates (or that the second plates 204_1 to 204_5 are all in contact with the elastic body 202). The processing unit 214 calculates all areas of the region surrounded by the second plates 204_ 1-204 _5 as the areas of the compressed electrodes corresponding to the specific force. Alternatively, if the second capacitance value C _1 corresponding to the second plate 204_1 is smaller than the predetermined capacitance value, it is determined that the second plate 204_1 is an uncompressed second plate (or a second plate not in contact with the elastic body 202). When the second capacitance values C _2 to C _5 corresponding to the second polar plates 204_2 to 204_5 are all greater than the predetermined capacitance value, the second polar plates 204_2 to 204_5 are all compressed second polar plates (or the second polar plates 204_2 to 204_5 are all in contact with the elastic body 202). The processing unit 214 calculates all areas of the region surrounded by the second plates 204_ 2-204 _5 as the areas of the compressed electrodes corresponding to the specific forces.
Similarly, when different forces are applied to the first plate 200, the processing unit 214 can determine the first capacitance values corresponding to the different pressing forces and obtain the compression electrode areas corresponding to the different forces. After the first capacitance values corresponding to different pressing forces and the compressed electrode areas corresponding to different forces are obtained, the relationship curve characteristics of the first capacitance values corresponding to different forces and the compressed electrode areas under the set electrode connection combination configuration can be determined.
In step 506, the processing unit 214 stores the electrode connection configuration set in step 202, the correspondence between the first capacitance values and the compressed electrode areas corresponding to the different forces in the storage unit 216. When the user selects the electrode connection configuration, the most suitable electrode connection configuration can be selected according to the electrode connection configuration stored in the storage unit 216, the correspondence relationship between the first capacitance value and the compressed electrode area. For example, as shown in fig. 7, fig. 7 is a schematic diagram of characteristic curves obtained under different electrode connection configurations according to an embodiment of the present invention. In a first electrode connection configuration, the relationship between the first capacitance and the compressive electrode area obtained by the pressure sensor 20 corresponding to different amounts of pressing force can be represented by the characteristic curve L1. In a second electrode connection configuration, the relationship between the first capacitance and the compressive electrode area obtained by the pressure sensor 20 corresponding to different amounts of pressing force can be represented by the characteristic curve L2. In this case, the user can select the electrode connection configuration according to the electrode connection configuration stored in the storage unit 216, and the corresponding relationship between the first capacitance and the compressed electrode area (i.e. the characteristic curves L1, L2).
In brief, the pressure sensor 20 can obtain the capacitance and the detected compressed electrode area of the first plate 200 corresponding to different forces according to the process 50, and obtain the relationship curve between the pressing force and the capacitance corresponding to different electrode connection configurations, wherein the user can select the electrode connection configuration according to the requirement by himself or the system can determine the electrode connection configuration according to the relationship curve between the pressing force and the capacitance to select the electrode connection configuration most suitable for the requirement of the user, so as to perform the operation of the pressure sensing function according to the selected electrode connection configuration during the normal operation.
Furthermore, the pressure sensor 20 can obtain a better electrode connection configuration according to the process 50 and various electrode connection configurations, and can also determine whether to conform to a target linear curve according to the obtained capacitance value, and adjust the coupling configuration of the second plate 204 in real time to obtain a desired linear curve. The operation of the pressure sensor 20 for real-time adjustment can be summarized as a process 60, please refer to fig. 6, which is a pressure sensing process 60 according to an embodiment of the present invention, the process 60 includes the following steps:
step 600: and starting.
Step 602: a certain force is exerted on the pressure sensor.
Step 604: the capacitance of the first plate corresponding to the specific force and the area of the compressed electrode are detected.
Step 606: comparing the obtained capacitance value with a default curve, and judging whether the capacitance value difference is within a preset difference value; if yes, go to step 610, otherwise go to step 608.
Step 608: adjusting the electrode coupling configuration of the second electrode plate.
Step 610: the processing unit judges whether the applied specific weight is less than the maximum weight; if yes, go to step 612, otherwise go to step 614.
Step 612: the unit weight is increased to a specific weight.
Step 614: and (6) ending.
Therefore, the pressure sensor 20 can sense the capacitance and the area of the detection compression electrode in real time according to the process 60, compare the sensed capacitance and the area of the detection compression electrode with the default curve, and adjust the relationship curve between the pressing force and the capacitance according to the comparison result.
In detail, when a specific pressure is applied to the pressure sensor 20 (step 602), the processing unit 214 senses a first capacitance value and compresses an electrode area (step 604). It is noted that the processing unit 214 stores a default curve, which is a relationship curve of the amount of pressing force and the capacitance value for determining linearity, and after the processing unit 214 obtains the first capacitance value and compresses the electrode area, the relationship curve is further compared with the default curve to determine whether the difference between the default curve and the first capacitance value is within a predetermined difference, so as to conform to the characteristics of the amount of pressing force and the capacitance value (step 606). When the capacitance is too large, the processing unit 214 adjusts the electrode coupling configuration to indicate that a portion of the second plate is coupled to the ground Gnd, so as to reduce the capacitance sensed between the first plate 200 and the second plate 204. Conversely, when the capacitance is too small, the processing unit 214 adjusts the electrode coupling configuration to indicate the state of the second plate 204 coupled to the ground Gnd to maintain the linear relationship between the amount of pressing force and the capacitance (step 608). After the processing unit 214 determines that the obtained capacitance value conforms to the linear relationship of the default curve, the processing unit 214 further determines whether the applied specific pressure is less than the maximum pressure (step 610). If the applied specific weight is less than the maximum weight, a unit pressure is increased to the specific weight to continue the sensing of the amount of pressing force and the capacitance (step 612). If not, then the process ends (i.e., step 614) if the specific weight applied is greater than or equal to the maximum weight.
It is noted that in the process 60, compared to the process 50, the pressure sensor 20 can sense the amount of the pressing force and the capacitance in real time according to the process 60, and accordingly compare the sensed values with the stored default curve to obtain the desired electrode coupling configuration. According to the process 60, the pressure sensor 20 does not need to obtain the relationship curve between the amount of pressure applied to the electrodes and the capacitance value in different electrode connection configurations, and the default curve is used as the dependency of the linearity, so that the electrode connection configuration meeting the linearity requirement can be obtained by real-time determination, and the operation of the pressure sensing function during the normal operation period can be provided.
It should be noted that the foregoing embodiments are merely illustrative of the concepts of the present invention, and various modifications can be made by those skilled in the art without limitation. For example, the control unit 210 couples part of the second plate 204 to the ground Gnd according to the electrode coupling configuration to adjust the capacitance sensed on the first plate 200, not only coupling part of the second plate 204 to the ground Gnd, but also coupling part of the second plate 204 to be in a floating state according to the system requirement, as long as the capacitance sensed on the first plate 200 can be changed. In addition, the arrangement of the second plates 204 is not limited to a single row and parallel arrangement, and the shape or size is not limited to a rectangle or the same size. Preferably, the arrangement, shape or size of the second plate 204 can be adjusted according to the system requirements to obtain better linearity.
Referring to fig. 8 to 11, fig. 8 to 11 are schematic diagrams illustrating a second plate according to an embodiment of the invention. As shown in fig. 8, the second plates are spaced apart by the same distance and are arranged in parallel rectangular shapes. The second plates may have different widths, and as shown in fig. 8, the second plate at the center position has a wider width, and the width thereof is gradually decreased as the distance from the center position increases. The distance between the two second pole plates can be different. As shown in fig. 9, each of the second plates has a rectangular shape with the same shape and is arranged in parallel with each other, however, the second plates are spaced apart from each other at a distance that gradually decreases as the distance from the center position increases. As shown in fig. 10, the second plate has two sets of metal in parallelogram shape, each set of rectangular metal has the same shape and is arranged in parallel, and the two sets of rectangular metal are symmetrical to each other according to the center position. As shown in fig. 11, the second plate is a double row rectangular metal, the width of the second plate, which is closer to the center position, of the rectangular metal in the upper row is wider, and the width decreases with the distance from the center position; the second plate, which is located closer to the center position, has a narrower width, and the width increases with the distance from the center position.
In summary, the conventional pressure sensor is limited by structural factors when performing pressure sensing, so that the applied pressure and the measured capacitance cannot present a linear relationship, which seriously affects the sensitivity of the user during touch control. In contrast, the pressure sensor of the present invention provides a more linear sensing by adjusting the input of the driving signal of the second plate, so as to improve the user experience. In addition, the pressure sensor of the invention measures the capacitance by the elastic body sensing pressure, the first polar plate and the second polar plate, and the processing unit further judges the coupling relation of the second polar plate so as to obtain better curve characteristics of the relation between the pressing force and the capacitance value. Therefore, when the pressure-feedback type pressure-feedback linear pressure-feedback type pressure-feedback device is used, a user can obtain satisfactory linear signal feedback according to the pressure, and the satisfaction degree of the user when the user uses a product is further improved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A pressure sensor, comprising:
a first electrode plate;
a plurality of second electrode plates;
the elastic body is arranged between the first polar plate and the plurality of second polar plates;
a first switch, including a first end coupled to the first electrode plate, and a second end selectively coupled to a receiving end of the first electrode plate or a grounding end;
a plurality of second switches, wherein each second switch comprises a first end coupled to one of the second electrode plates and a second end selectively coupled to a second electrode plate receiving end, the ground end or a driving signal end; and
a control unit for generating a control signal to control the first switch and the plurality of second switches;
wherein, during a normal operation, the control unit generates the control signal according to an electrode connection configuration, the electrode connection configuration includes at least a portion of the plurality of second plates coupled to the ground terminal or in a floating state and the remaining second plates coupled to the driving signal terminal,
during the normal operation, according to the control signal, the first terminal of the first switch is coupled to the first plate and the second terminal of the first switch is coupled to the first plate receiving terminal, and according to the control signal and the electrode connection configuration, at least a portion of the second terminals of the plurality of second switches are coupled to the ground terminal or in the floating state and the second terminals of the remaining second switches are coupled to the driving signal terminal, so as to connect the corresponding second plates to the driving signal terminal.
2. The pressure sensor of claim 1, further comprising
A driving unit coupled to the driving signal terminal for generating a driving signal; and
the processing unit is coupled to the first electrode plate receiving end and used for receiving a first sensing signal through the first electrode plate receiving end during the normal operation period and judging a first capacitance value corresponding to a first force according to the first sensing signal.
3. The pressure sensor of claim 2, wherein the processing unit is configured to set the electrode connection configuration during a test period, and the processing unit detects first plate capacitance values and detects compressive electrode areas corresponding to different forces based on the electrode connection configuration when the different forces are applied to the first plate.
4. The pressure sensor of claim 3, further comprising
And the storage unit is used for storing the electrode connection configuration, the first capacitance values corresponding to different forces and the corresponding relation of the area of the compression electrode.
5. The pressure sensor of claim 3, wherein upon application of the first force to the first plate, the control unit generates the control signal according to the electrode connection configuration such that the first end of the first switch is coupled to the first electrode plate and the second end of the first switch is coupled to the first electrode plate receiving end, second terminals of the at least a portion of the plurality of second switches are coupled to the ground terminal or switched to the floating state and second terminals of the remaining second switches are coupled to the driving signal terminal, the driving unit inputs the driving signal to the connected second polar plate through the driving signal end, the processing unit receives the first sensing signal through the first electrode plate receiving end and judges a first capacitance value corresponding to the first force according to the first sensing signal.
6. The pressure sensor of claim 3, wherein the control unit generates the control signal when the first force is applied to the first plate such that the first terminal of the first switch is coupled to the first plate and the second terminal of the first switch is coupled to the ground terminal to switch the first plate to the ground terminal, and each second switch is coupled to a corresponding second plate receiving terminal to couple each second plate to the corresponding second plate receiving terminal, and the processing unit receives a plurality of second sensing signals through the corresponding second plate receiving terminals to detect a plurality of second capacitance values corresponding to the plurality of second plates and determine a compressed second plate from among the plurality of second plates, and the processing unit calculates the area of the area covered by the second polar plate which is judged to be compressed to be the area of the compressed electrode corresponding to the first force.
7. The pressure sensor as claimed in claim 6, wherein for each second plate, the processing unit receives a second sensing signal through the corresponding second plate receiving end of each second plate and determines a second capacitance value corresponding to each second plate, the processing unit determines each second plate to be a compressed second plate when the second capacitance value corresponding to each second plate is greater than or equal to a predetermined capacitance value, and determines each second plate to be an uncompressed second plate when the second capacitance value corresponding to each second plate is less than the predetermined capacitance value.
8. A pressure sensing method is suitable for a pressure sensor, the pressure sensor comprises an elastic body, a first polar plate and a plurality of second polar plates, the elastic body is arranged between the first polar plate and the plurality of second polar plates, the pressure sensing method comprises the following steps:
setting an electrode connection configuration, wherein the electrode connection configuration comprises at least one part of the plurality of second plates coupled to a grounding end or switched to a floating state and the rest of the second plates coupled to a driving signal end;
applying different forces to the first plate and detecting first capacitance values and compressive electrode areas corresponding to the different forces according to the electrode connection configuration, wherein the applying different forces to the first plate and detecting first capacitance values and compressive electrode areas corresponding to the different forces according to the electrode connection configuration comprises:
coupling the first plate to a first plate receiving terminal and coupling the at least a portion of the plurality of second plates to the ground or to the floating state and coupling the remaining second plates to the driving signal terminal according to the electrode connection configuration while applying a first force to the first plate; and
inputting a driving signal to the at least one portion of the plurality of second electrode plates through the driving signal terminal, and receiving a first sensing signal through the first electrode plate receiving terminal to determine a first capacitance corresponding to the first force; and
storing the electrode connection configuration, the first capacitance corresponding to different forces and the corresponding relation of the area of the compressed electrode.
9. A pressure sensing method is suitable for a pressure sensor, the pressure sensor comprises an elastic body, a first polar plate and a plurality of second polar plates, the elastic body is arranged between the first polar plate and the plurality of second polar plates, the pressure sensing method comprises the following steps:
setting an electrode connection configuration, wherein the electrode connection configuration comprises at least one part of the plurality of second plates coupled to a grounding end or switched to a floating state and the rest of the second plates coupled to a driving signal end;
applying different forces to the first plate and detecting first capacitance values and compressive electrode areas corresponding to the different forces according to the electrode connection configuration, wherein the applying different forces to the first plate and detecting first capacitance values and compressive electrode areas corresponding to the different forces according to the electrode connection configuration comprises:
when a first force is applied to the first polar plate, the first polar plate is switched to a grounding end, and the plurality of second polar plates are respectively coupled to corresponding second polar plate receiving ends; and
detecting a plurality of second capacitance values corresponding to the plurality of second polar plates and determining a compressed second polar plate from the plurality of second polar plates; and
calculating the area of the area covered by the second polar plate which is judged to be compressed to be used as the area of the compressed electrode corresponding to the first force; and
storing the electrode connection configuration, the first capacitance corresponding to different forces and the corresponding relation of the area of the compressed electrode.
10. The pressure sensing method of claim 9, wherein detecting a plurality of second capacitance values corresponding to the plurality of second plates and determining a compressed second plate from among the plurality of second plates comprises:
for each second polar plate, receiving a second sensing signal through a corresponding second polar plate receiving end of each second polar plate to judge a second capacitance value corresponding to each second polar plate;
when the second capacitance value corresponding to each second polar plate is greater than or equal to a preset capacitance value, judging that each second polar plate is a compressed second polar plate; and
and when the second capacitance value corresponding to each second polar plate is smaller than the preset capacitance value, judging that each second polar plate is an uncompressed second polar plate.
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| CN107025016A (en) * | 2016-01-18 | 2017-08-08 | 速博思股份有限公司 | Capacitive pressure sensing device and method |
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| CN1388364A (en) * | 1995-07-28 | 2003-01-01 | 日本代纳马特株式会社 | Pressure sensor |
| US7239153B2 (en) * | 2002-03-01 | 2007-07-03 | Idex Asa | Sensor module for measuring surfaces |
| CN101770309A (en) * | 2009-01-05 | 2010-07-07 | 财团法人工业技术研究院 | Sensing device as well as scanning and driving method thereof |
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