CN111913595B - Touch pad pressing force detection system and method - Google Patents
Touch pad pressing force detection system and method Download PDFInfo
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- CN111913595B CN111913595B CN201910387653.2A CN201910387653A CN111913595B CN 111913595 B CN111913595 B CN 111913595B CN 201910387653 A CN201910387653 A CN 201910387653A CN 111913595 B CN111913595 B CN 111913595B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
- G06F3/03547—Touch pads, in which fingers can move on a surface
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/0414—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using force sensing means to determine a position
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/0416—Control or interface arrangements specially adapted for digitisers
- G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
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Abstract
The system comprises a touch pad, an acquisition module, a compensation module, a conversion module and a processing module; the acquisition module is used for detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity; the compensation module is connected with the acquisition module and is used for outputting a compensation current with a preset limit through the leakage current of the metal oxide semiconductor transistor to compensate the output voltage drift caused by the leakage current of the rear-stage circuit and the piezoelectric sensor; the conversion module is respectively connected with the acquisition module and the compensation module and is used for generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current and converting the sampling voltage value into a voltage signal; the processing module is connected with the conversion module and is used for calculating and obtaining touch pressure information according to the voltage signals.
Description
Technical Field
The invention relates to the field of electromechanical interaction, in particular to a touch pad pressing force detection system and method.
Background
Electronic devices such as portable mobile phones and tablet computers exist in the market at present, and main operations are completed through a touch screen. Touch screens are becoming more popular because of their ease of operation and their lower price, and are particularly advantageous in that they help users achieve the same operational goals without having to move the mouse and tap the keyboard more frequently. The touch screen generally comprises a touch panel, a touch response component, a touch control system, a driver and the like, and the touch response component mainly adopts the technical schemes including a resistive type, a capacitive type, an infrared type, a surface acoustic wave type and the like, which have a common disadvantage except the limitation of the autogenous technology, namely, the technical schemes generally only provide position information and cannot provide pressure or pressing force information.
With the development and advancement of technology, touch devices and touch screens have emerged that can provide static pressure, but with fewer users; for example, only the MacBook Pro notebook product of apple corporation, which supports the function of pressing force sensing and recognition, among notebook manufacturers, adopts the Force Touch TrackPad scheme. Four pressure sensors and a Tapt Engine haptic feedback vibrator are used in the scheme. The pressure sensing touch pad of MacBook Pro is provided with a pressure sensor at four corners of the touch pad, so that the whole touch pad can sink for a certain distance, and meanwhile, the operation feeling of each area of the touch pad is the same; when the pressure on the finger is increased to change the loop resistance in the sensor, the pressure of the finger on the touch pad can be perceived through measuring the variable of the resistance; the pressure sensing device on the Macbook Pro has the problems of complex mechanism, large occupied notebook computer assembly space, high power consumption and high cost.
Disclosure of Invention
The invention aims to provide a touch pad pressing force detection system and method which are simple in structure and accurate in measurement result.
In order to achieve the above object, the touch pad pressing force detection system provided by the present invention specifically includes: the system comprises a touch control panel, an acquisition module, a compensation module, a conversion module and a processing module; the acquisition module is used for detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity; the compensation module is connected with the acquisition module and is used for outputting a compensation current with a preset limit through the leakage current of the metal oxide semiconductor transistor to compensate the output voltage drift caused by the leakage current of the rear-stage circuit and the piezoelectric sensor; the conversion module is respectively connected with the acquisition module and the compensation module and is used for generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current and converting the sampling voltage value into a voltage signal; the processing module is connected with the conversion module and is used for calculating and obtaining touch pressure information according to the voltage signals.
In the above touch pad pressing force detection system, preferably, the conversion module further includes an integration circuit, and the integration circuit is configured to convert a sum of the sampled charge and the compensation current into a sampled voltage.
In the above touch pad pressing force detection system, preferably, the conversion module further includes a preprocessing circuit, and the preprocessing circuit is configured to amplify and filter the voltage signal, and process the processed voltage signal with the processing module.
In the above touch pad pressing force detection system, preferably, the system further includes a reset circuit, where the reset circuit is disposed between the collection module and the conversion module, and is configured to control, through the processor and the CMOS tube, circuit reset of the collection module and the conversion module, and eliminate voltage reference offset between the collection module and the conversion module.
In the above touch pad pressing force detection system, preferably, the reset circuit controls the circuit reset of the acquisition module and the conversion module by controlling the on-off of the CMOS tube through one IO of the processor; when the IO port is controlled to output high level, the CMOS tube is controlled to be opened, so that the circuits of the acquisition module and the conversion module are reset; and when the output of the IO port is at a low level, the CMOS tube is controlled to be closed, so that the circuits of the acquisition module and the conversion module normally operate.
In the above touch pad pressing force detection system, preferably, a source electrode of the metal oxide semiconductor transistor in the compensation circuit is connected with an anode of the voltage source, a gate electrode of the metal oxide semiconductor transistor is connected with a cathode of the voltage source through a preset resistor, and a drain electrode of the metal oxide semiconductor transistor is connected with an operational amplifier forward input end between the acquisition module and the conversion module.
In the above touch pad pressing force detection system, preferably, when the touch pad is smaller than a predetermined size threshold and the piezoelectric sensors are plural; the piezoelectric sensors are connected in parallel; the piezoelectric sensor is adhered to the support of the touch pad through curing glue.
In the above touch pad pressing force detection system, preferably, when the touch pad is greater than a predetermined size threshold, and the piezoelectric sensors are plural; the piezoelectric sensors are connected in series every two; the piezoelectric sensor is adhered to the PCB of the touch control plate through curing glue or welded to the PCB of the touch control plate through welding.
In the above touch pad pressing force detection system, preferably, the processing module further includes a calculating unit, where the calculating unit is configured to calculate and obtain a fluctuation value corresponding to the voltage signal according to the voltage signal; obtaining the touch pressure energy value according to the difference value between the fluctuation value and a pre-stored reference value; and obtaining touch pressure information according to the touch pressure energy value.
In the above touch pad pressing force detection system, preferably, the processing module further includes a calibration unit, where the calibration module is connected to the processing module, and is configured to obtain a touch position at which deformation occurs on the touch pad, and obtain a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, and delivering the corrected voltage signal to the computing unit to compute the touch pressure energy value.
In the above touch pad pressing force detection system, preferably, the computing unit is further configured to compare the touch pressure energy value with one or more preset thresholds, and obtain touch pressure information according to a comparison result; or obtaining one or more preset thresholds according to the touch position; and comparing the touch pressure energy value with the preset threshold corresponding to the touch position, and obtaining touch pressure information according to a comparison result.
In the above touch pad pressing force detection system, preferably, the system further includes a noise filtering module, where the noise filtering module is connected to the processing module, and is configured to compare the touch pressure information with a predetermined threshold, and output the touch pressure information to an external device according to a comparison result.
The invention also provides a method for detecting the pressing force of the touch pad, which comprises the following steps: detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity; obtaining preset compensation current according to a preset compensation circuit, and outputting the compensation current to compensate the output voltage drift caused by the leakage current of the metal oxide semiconductor transistor and the self leakage of the piezoelectric sensor; and generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current, converting the sampling voltage value into a voltage signal, and calculating according to the voltage signal to obtain touch pressure information.
In the above method for detecting a pressing force of a touch pad, preferably, comparing the voltage signal with a predetermined reference signal, and obtaining touch pressure information according to a comparison result includes: acquiring a touch position where deformation occurs on the touch pad, and acquiring a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, comparing the corrected voltage signal with a preset reference signal, and obtaining touch pressure information according to a comparison result.
In the above method for detecting a pressing force of a touch pad, preferably, the correction coefficient is obtained by performing gridding calibration on the touch pad in advance.
In the above touch pad pressing force detection method, preferably, the method further includes comparing the touch pressure information with a predetermined threshold, and outputting the touch pressure information to an external device according to a comparison result.
The invention also provides a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the above method when executing the computer program.
The present invention also provides a computer readable storage medium storing a computer program for executing the above method.
The system and the method for detecting the pressing force of the touch pad can realize the detection of the pressing force information of the finger on the touch pad on the basis of reducing the hardware cost, and not only have simpler structure and lighter weight, but also are more accurate and save electricity.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate and together with the description serve to explain the invention. In the drawings:
fig. 1 is a schematic structural diagram of a touch pad pressing force detection system according to an embodiment of the present invention;
FIG. 2 is a schematic block diagram of a touch pad pressing force detection system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a sensor installation of a touch pad pressing force detection system according to an embodiment of the present invention;
fig. 4 is a schematic diagram showing the combination of a sensor and an FPC of the touch pad pressing force detection system according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a compensation circuit of a touch pad pressing force detection system according to an embodiment of the present invention;
fig. 6 is a flowchart of a method for detecting pressing force of a touch pad according to an embodiment of the invention;
FIG. 7 is a diagram illustrating gridding calibration according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a pressing force detection method of a touch pad according to an embodiment of the invention.
Detailed Description
The following will describe embodiments of the present invention in detail with reference to the drawings and examples, thereby solving the technical problems by applying technical means to the present invention, and realizing the technical effects can be fully understood and implemented accordingly. It should be noted that, as long as no conflict is formed, each embodiment of the present invention and each feature of each embodiment may be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.
In the description of the present specification, reference to the terms "one embodiment," "a particular embodiment," "for example," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. The sequence of steps involved in the embodiments is used to schematically illustrate the practice of the present application, and is not limited thereto and may be appropriately adjusted as desired.
Referring to fig. 1, the touch pad pressing force detection system provided by the present invention specifically includes: the system comprises a touch control panel, an acquisition module, a compensation module, a conversion module and a processing module; the acquisition module is used for detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity; the compensation module is connected with the acquisition module and is used for outputting a compensation current with a preset limit through the leakage current of the metal oxide semiconductor transistor NMOS to compensate the output voltage drift caused by the leakage of the rear-stage circuit and the piezoelectric sensor; the conversion module is respectively connected with the acquisition module and the compensation module and is used for generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current and converting the sampling voltage value into a voltage signal; the processing module is connected with the conversion module and is used for calculating and obtaining touch pressure information according to the voltage signals. Wherein the conversion module may further comprise an integration circuit for converting the sum of the sampled charge and the compensation current into a sampled voltage. The number of the piezoelectric sensors can be one, two or four, and the specific number of the piezoelectric sensors can be selected according to actual needs, so that the invention is not limited in any way. In the above embodiments, the touch pad may be a rigid medium or an elastic wave propagation medium combined with the rigid medium, and may be selected and used in terms of structure according to specific requirements, for example: a planar structure, a curved structure, and a planar or curved structure with perforations; the invention further provides a compensation module for overcoming the problem of too fast signal attenuation in the current transmission process by the compensation module; then, based on the sum of the compensation current and the sampling current, converting to obtain a corresponding sampling voltage value so as to obtain a subsequent voltage signal; at the moment, the pressing force received by the touch pad during touch can be judged based on the difference value between the voltage signal and a reference signal; the reference signal may be obtained by collecting a sampling voltage signal of the touch pad in a non-pressing state before detection, and the present invention will not be described in detail herein.
In the above embodiments, the piezoelectric sensor includes a piezoelectric ceramic sensor, a piezoelectric thin film sensor, a piezoelectric crystal sensor, or other sensor having a piezoelectric effect.
In the foregoing embodiment, in order to facilitate accuracy of subsequent calculation, in an embodiment of the present invention, the conversion module further includes a preprocessing circuit, where the preprocessing circuit is configured to perform amplification filtering processing on the voltage signal, and send the processed voltage signal to the processing module for processing. It should be noted that, in actual operation, the preprocessing circuit may include one or more of a filtering processing circuit, an amplifying processing circuit, a rectifying processing circuit, a switching processing circuit, a fourier transform processing circuit, and a wavelet transform processing circuit, so as to obtain a preprocessed voltage flow. Therefore, unnecessary errors caused by irrelevant signal data to a post-calculation result are further eliminated, and when the processing flow can be finished through the prior art, the description is omitted.
In order to improve the voltage reference offset problem (temperature drift) of the touch pad pressing force detection system, in an embodiment of the present invention, the system may further include a reset circuit, which is disposed between the acquisition module and the conversion module, and is configured to control the circuit reset of the acquisition module and the conversion module through a processor (such as a singlechip) and a CMOS tube, so as to eliminate the voltage reference offset between the acquisition module and the conversion module. The reset circuit controls the circuit reset of the acquisition module and the conversion module by controlling the on-off of the CMOS tube through one IO of the processor; when the IO port is controlled to output high level, the CMOS tube is controlled to be opened, so that the circuits of the acquisition module and the conversion module are reset; and when the output of the IO port is at a low level, the CMOS tube is controlled to be closed, so that the circuits of the acquisition module and the conversion module normally operate.
In the above embodiment, the specific connection mode of the compensation circuit may connect the source electrode of the metal oxide semiconductor transistor NMOS with the positive electrode of the voltage source, the gate electrode of the metal oxide semiconductor transistor NMOS is connected with the negative electrode of the voltage source through a preset resistor, and the drain electrode of the metal oxide semiconductor transistor NMOS is connected to the operational amplifier positive input end between the collection module and the conversion module, and the specific layout mode may be shown in fig. 5; of course, other modes may be adopted in the actual working, the invention is not limited in particular, and the person skilled in the art can choose the mode according to the actual needs and the space design.
In order to improve the accuracy of pressure detection during practical use, in an embodiment of the present invention, different mounting manners may be adopted for touch pads of different sizes, for example: referring to fig. 3, when the touch pad is smaller than a predetermined size threshold and the piezoelectric sensors 301 are plural; the piezoelectric sensors 301 are connected in parallel; wherein the piezoelectric sensor 301 is adhered to the support of the touch pad 302 by a curing adhesive. Referring to fig. 4, when the touch pad is greater than a predetermined size threshold and the piezoelectric sensors are plural; the piezoelectric sensors are connected in series every two; the piezoelectric sensor is adhered to the PCB of the touch control plate through curing glue or welded to the PCB of the touch control plate through welding. Specifically, referring to fig. 4 again, six piezoelectric sensors 401 are welded on a PCB402 of the touch pad, the cut parts are uniformly distributed along the outline of the PCB402, and the processing circuits thereof are also integrated on the PCB402 of the touch pad, wherein the PCB is further provided with a groove 403, the groove 403 is used for improving the signal receiving capability, and when the piezoelectric sensor is specifically installed, the piezoelectric sensor 401 is welded on the PCB402 through a welding layer 404, and the PCB402 is fixed on the circuit board or the inner casing of the electronic device through a reinforcing and colloid layer 405.
In order to avoid noise caused by unnecessary interference, in an embodiment of the present invention, the system further includes a noise filtering module, where the noise filtering module is connected to the processing module, and is configured to compare the touch pressure information with a predetermined threshold, and output the touch pressure information to an external device according to a comparison result. In actual operation, when the touch information is received by the touch pad and the pressing force value exceeds the pressing action triggering threshold, the pressing action is identified. The mathematical expression is as follows:
wherein button_state is a key state, button_state=1 indicates that the key is pressed; button_state=0 indicates that the key is released; f is the actual detected pressing force value; f (F) TH The force threshold is triggered for a pressing action. When the pressing force value in the current sampling period is lower than the triggering threshold value, the pressing action is finished, and meanwhile, the accumulated values of all channel sensor signals are cleared; of course, in actual practice, a plurality of pressing actions may be providedTrigger force threshold, F TH1 、F TH2 、F TH3 Up to F THn Thus, by comparing the button_state with the pressing action triggering force threshold value, the region to which the current pressing action belongs can be confirmed, and the multi-stage judgment of the pressing force is realized; in actual operation, a plurality of force levels are adopted specifically, the specific limit value of each force level is not limited in the invention, and the person skilled in the art can select and set the force level according to actual needs.
The processing module further comprises a calculation unit, wherein the calculation unit is used for calculating and obtaining a fluctuation value corresponding to the voltage signal according to the voltage signal; obtaining the touch pressure energy value according to the difference value between the fluctuation value and a pre-stored reference value; and obtaining touch pressure information according to the touch pressure energy value. The touch pressure energy value can be calculated by the following formula:or->
In the above formula, m is the number of the acquired signal points; n is the number of signal points determined by selecting the voltage signal wavelength with a predetermined length according to the actual situation, and the related person in the art can select and set according to the actual requirement, and the invention is not limited in any way; e is the touch pressure energy value corresponding to the voltage signal. Of course, in actual operation, the calculating method of the touch pressure energy value is not limited to the above method, and a person skilled in the art can select a suitable method to calculate the touch pressure energy value according to actual needs, which is not limited in any way herein.
In view of the difference of the structure of the touch pad and the difference of the installation modes on different electronic devices, certain errors can exist in the method for identifying the pressing impulse of the touch pad under the same pressing force at different pressing positions on the touch pad, so that the errors are reduced; in the above touch pad pressing force detection system, preferably, the processing module further includes a calibration unit, where the calibration module is connected to the processing module, and is configured to obtain a touch position at which deformation occurs on the touch pad, and obtain a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, and delivering the corrected voltage signal to the computing unit to compute the touch pressure energy value. Referring to fig. 7, the correction coefficient may be obtained by a grid calibration method, for example, according to the position relationship between the pressing position and each calibration point on the touch pad and the correction coefficient of each calibration point, the correction coefficient corresponding to the pressing position is obtained by a bilinear interpolation method. In this way, the error is further reduced mainly by detecting the pressing position when pressing occurs, wherein the pressing position can be obtained through the detection of the existing touch screen, and can also be obtained by utilizing the pressing signal detected by the piezoelectric sensor, and the invention is not described in detail herein.
In the above embodiment, in order to facilitate subsequent application, the computing unit provided by the present invention is further configured to compare the touch pressure energy value with one or more preset thresholds, and obtain touch pressure information according to a comparison result; or obtaining one or more preset thresholds according to the touch position; and comparing the touch pressure energy value with the preset threshold corresponding to the touch position, and obtaining touch pressure information according to a comparison result. Specifically, in actual operation, after the computing unit computes and obtains the touch pressure energy value, the touch pressure energy value may be compared with one or more preset thresholds to determine whether the current touch pressure meets a preset standard, for example; when intelligent equipment such as a tablet computer and a mobile phone is started by adopting pressure control, only the touch pressure is required to meet a threshold value, and the touch pressure energy value is compared with the preset threshold value at the moment, if the touch pressure energy value is larger than the preset threshold value, the starting operation can be started; if multi-stage pressure operation of the device is required, for example, a photo is started in a large-pressing-force state, music is started in a medium-stage pressure state, a screen is started in a small-pressure state, and the like, the touch pressure energy value can be respectively compared with a plurality of preset thresholds, so that a final control scheme, namely touch pressure information, is obtained; of course, as mentioned above, the problem of the difference in the structure of the touch pad and the difference in the installation manner on different electronic devices may be that one or more preset thresholds are set for different positions in actual operation, and then the one or more steps of force comparison are performed after the corresponding preset thresholds are obtained through the touch positions; of course, in actual working, due to different application scenarios and requirements, a person skilled in the art can freely select the combination of the above embodiments according to actual requirements, and the present invention is not limited in this way.
In actual operation, the touch pad pressing force detection device provided by the invention can be shown in fig. 2, and when the touch pad pressing force detection device is applied to touch pad, finger pressing signals are mainly collected through a piezoelectric sensor, and then the finger pressing signals are subjected to filtering, amplifying and other processes through a signal processing circuit and sent to a processor MCU; the processor MCU performs operation processing through the comparison method or other pressing force recognition algorithms, then transmits the calculated force value to the touch pad MCU through the I2C or SPI, then the touch pad MCU fuses the detected position coordinate value and the force value into an HID frame, and the HID frame is uploaded to a notebook computer main board or CPU through the I2C or USB or BTH communication interface and is transmitted to an operating system. The pressing force recognition algorithm can comprise an algorithm such as a deep learning algorithm and a neural network learning algorithm, and in practical application, a large number of pressing detection can be performed in the early stage, a voltage signal output by the touch pad pressing force detection system is used as an input signal, a learning model is built through the deep learning algorithm, and after the learning model is trained through the input signal, pressing force values corresponding to different voltage signals can be obtained quickly through the learning model.
Referring to fig. 6, the present invention further provides a method for detecting pressing force of a touch pad, the method comprising: s601, detecting deformation quantity of the touch pad caused by touch through one or more piezoelectric sensors attached to the touch pad, and generating sampling charges according to the deformation quantity; s602, obtaining preset compensation current according to a preset compensation circuit, and outputting output voltage drift caused by leakage current of a metal oxide semiconductor transistor and leakage current of a piezoelectric sensor and a compensation post-stage circuit; s603, generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current, and converting the sampling voltage value into a voltage signal; s604 compares the voltage signal with a predetermined reference signal, and obtains touch pressure information according to the comparison result.
In the above embodiment, comparing the voltage signal with a predetermined reference signal, and obtaining touch pressure information according to the comparison result includes: acquiring a touch position where deformation occurs on the touch pad, and acquiring a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, comparing the corrected voltage signal with a preset reference signal, and obtaining touch pressure information according to a comparison result. The correction coefficient can be obtained by performing gridding calibration on the touch pad in advance.
In general, as shown in fig. 8, when a finger presses the touch pad, a piezoelectric sensor on the touch pad senses a pressing signal A1, the pressing sensing signal A1 is preprocessed by a signal processing circuit, a pressing effective signal A2 is obtained after processes including filtering, amplifying and the like, and the pressing effective signal A2 is converted into a digital signal D1 after analog-to-digital conversion; the digital signal D1 is subjected to digital filtering again, and noise peculiar to equipment is filtered, so that a purer sampling signal D2 is obtained; the digital signal D2 is subjected to the above-mentioned pressing recognition algorithm to calculate a pressing force value. The pressing force value is further checked through the position information, so that final touch pressure information is output.
The invention also provides a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the above method when executing the computer program.
The present invention also provides a computer readable storage medium storing a computer program for executing the above method.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (17)
1. The touch pad pressing force detection system is characterized by comprising a touch pad, an acquisition module, a compensation module, a conversion module and a processing module;
the acquisition module is used for detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity;
the compensation module is connected with the acquisition module and is used for outputting a compensation current with a preset limit through the leakage current of the metal oxide semiconductor transistor to compensate the output voltage drift caused by the leakage current of the rear-stage circuit and the piezoelectric sensor; the source electrode of the metal oxide semiconductor transistor in the compensation module is connected with the positive electrode of the voltage source, the grid electrode of the metal oxide semiconductor transistor is connected with the negative electrode of the voltage source through a preset resistor, and the drain electrode of the metal oxide semiconductor transistor is connected with the operational amplifier positive input end between the acquisition module and the conversion module;
the conversion module is respectively connected with the acquisition module and the compensation module and is used for generating a corresponding sampling voltage value according to the sum of the sampling charge and the compensation current and converting the sampling voltage value into a voltage signal;
the processing module is connected with the conversion module and is used for calculating and obtaining touch pressure information according to the voltage signals.
2. The touch pad compression force detection system of claim 1, wherein the conversion module further comprises an integration circuit for converting a sum of the sampled charge and the compensation current into a sampled voltage.
3. The touch pad pressing force detection system according to claim 1, wherein the conversion module further comprises a preprocessing circuit, and the preprocessing circuit is configured to amplify and filter the voltage signal, and to process the processed voltage signal with the processing module.
4. The touch pad compression force detection system of claim 1, further comprising a reset circuit disposed between the acquisition module and the conversion module for controlling circuit reset of the acquisition module and the conversion module by the processor and the CMOS tube to eliminate voltage reference offset between the acquisition module and the conversion module.
5. The touch pad pressing force detection system according to claim 4, wherein the reset circuit controls the circuit reset of the acquisition module and the conversion module by controlling the on-off of the CMOS tube through one IO of the processor; when the IO port is controlled to output high level, the CMOS tube is controlled to be opened, so that the circuits of the acquisition module and the conversion module are reset; and when the output of the IO port is at a low level, the CMOS tube is controlled to be closed, so that the circuits of the acquisition module and the conversion module normally operate.
6. The touch pad pressing force detection system of claim 1, wherein when the touch pad is less than a predetermined size threshold and the piezoelectric sensors are plural; the piezoelectric sensors are connected in parallel; the piezoelectric sensor is adhered to the support of the touch pad through curing glue.
7. The touch pad pressing force detection system of claim 1, wherein when the touch pad is greater than a predetermined size threshold and the piezoelectric sensors are plural; the piezoelectric sensors are connected in series every two; the piezoelectric sensor is adhered to the PCB of the touch control plate through curing glue or welded to the PCB of the touch control plate through welding.
8. The touch pad pressing force detection system according to claim 1, wherein the processing module further comprises a calculation unit, and the calculation unit is configured to calculate and obtain a fluctuation value corresponding to the voltage signal according to the voltage signal; obtaining the touch pressure energy value according to the difference value between the fluctuation value and a pre-stored reference value; and obtaining touch pressure information according to the touch pressure energy value.
9. The touch pad pressing force detection system according to claim 8, wherein the processing module further comprises a calibration unit, the calibration module is connected with the processing module, and is configured to obtain a touch position of the touch pad, where deformation occurs, and obtain a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, and delivering the corrected voltage signal to the computing unit to compute the touch pressure energy value.
10. The touch pad pressing force detection system according to any one of claims 8 or 9, wherein the computing unit is further configured to compare the touch pressure energy value with one or more preset thresholds, and obtain touch pressure information according to a comparison result;
or obtaining one or more preset thresholds according to the touch position; and comparing the touch pressure energy value with the preset threshold corresponding to the touch position, and obtaining touch pressure information according to a comparison result.
11. The touch pad pressing force detection system according to claim 1, further comprising a noise filtering module connected to the processing module, wherein the noise filtering module is configured to compare the touch pressure information with a predetermined threshold value, and output the touch pressure information to an external device according to a comparison result.
12. The method for detecting the pressing force of the touch pad is characterized by comprising the following steps:
detecting deformation quantity of the touch control plate caused by touch through one or more piezoelectric sensors attached to the touch control plate, and generating sampling charges according to the deformation quantity;
obtaining preset compensation current according to a preset compensation circuit, and outputting the compensation current to compensate the output voltage drift caused by the leakage current of the metal oxide semiconductor transistor and the self leakage of the piezoelectric sensor; the source electrode of the metal oxide semiconductor transistor in the compensation circuit is connected with the positive electrode of the voltage source, the grid electrode of the metal oxide semiconductor transistor is connected with the negative electrode of the voltage source through a preset resistor, and the drain electrode of the metal oxide semiconductor transistor is connected with the operational amplifier positive input end between the piezoelectric sensor and the rear-stage circuit;
generating a corresponding sampled voltage value according to the sum of the sampled charge and the compensation current, and converting the sampled voltage value into a voltage signal;
and calculating according to the voltage signal to obtain touch pressure information.
13. The method of claim 12, wherein comparing the voltage signal with a predetermined reference signal, and obtaining touch pressure information based on the comparison result comprises: acquiring a touch position where deformation occurs on the touch pad, and acquiring a pre-stored correction coefficient according to the touch position; and correcting the voltage signal according to the correction coefficient, comparing the corrected voltage signal with a preset reference signal, and obtaining touch pressure information according to a comparison result.
14. The touch pad pressing force detection method according to claim 13, wherein the correction coefficient is obtained by performing gridding calibration on the touch pad in advance.
15. The touch pad pressing force detection method according to claim 12, further comprising comparing the touch pressure information with a predetermined threshold value, and outputting the touch pressure information to an external device according to the comparison result.
16. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method of any of claims 12 to 15 when executing the computer program.
17. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program for executing the method of any one of claims 12 to 15.
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