Touch detection method, device and equipment for interactive tablet and storage medium

Abstract

The embodiment of the present application provides a touch detection method, device and equipment for an interactive panel and a computer storage medium, which comprises the following steps: collecting an infrared pen-down signal generated when a touch object touches a screen based on an infrared touch module; determining a first time point before the generation time point of the infrared pen-down signal; performing signal reset processing on a piezoelectric sensor at the first time point; ensuring that when the touch object touches the screen, the sensor signal collection accuracy will not be affected by long-time error accumulation; collecting a sensor signal based on the piezoelectric sensor after the signal reset processing; determining an elastic wave signal and a static force signal based on the sensor signal; and determining touch feature data of the touch object according to the static force signal and / or the elastic force signal, so as to improve the accuracy of the touch feature data, that is, the touch detection accuracy of the interactive panel.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to touch detection methods, apparatus, devices and computer storage media for interactive flat panels. Background Technology

[0002] Interactive flat panels are widely used in scenarios such as meetings and education. They support touch services, allowing users to write on the screen using touch objects. When the interactive flat panel detects a touch object, it generates touch feature data, which the screen then uses to respond.

[0003] In related technologies, touch feature data can be detected using elastic wave sensors. However, elastic wave signals are only generated when a stylus collides with glass at a relatively high speed. When the stylus collides with glass with a slower force, the amplitude of the generated elastic wave signal is small, which may lead to missed signals and thus result in the inability to collect accurate touch feature data. Summary of the Invention

[0004] The main purpose of this specification is to provide a touch detection method, apparatus, device, and storage medium for interactive flat panels, aiming to accurately collect touch feature data of touched objects, thereby improving the service quality of interactive flat panels. The technical solution is as follows:

[0005] In a first aspect, embodiments of this application provide a touch detection method for an interactive flat panel, comprising:

[0006] Based on the infrared touch module, the infrared pen signal generated when a touch object touches the screen is collected;

[0007] Determine the first moment before the generation of the infrared pen-drop signal, and perform signal reset processing on the piezoelectric sensor at the first moment;

[0008] Acquire the sensor signal collected by the piezoelectric sensor after signal reset processing;

[0009] Elastic wave signals and static force signals are determined based on sensor signals;

[0010] Touch feature data of the object being touched are determined based on elastic wave signals and / or static force signals.

[0011] Secondly, embodiments of this application provide a touch detection device for an interactive flat panel, comprising:

[0012] The infrared module is used to collect infrared pen signals generated when a touch object touches the screen, based on the infrared touch module;

[0013] The reset module is used to determine the first moment before the generation of the infrared pen-drop signal and to perform signal reset processing on the piezoelectric sensor at the first moment.

[0014] The acquisition module is used to acquire the sensor signal collected by the piezoelectric sensor after signal reset processing;

[0015] The signal separation module is used to determine elastic wave signals and static force signals based on sensor signals;

[0016] The identification module is used to determine the touch feature data of the touched object based on elastic wave signals and / or static force signals.

[0017] Thirdly, embodiments of this application provide an electronic device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the method described above.

[0018] Fourthly, embodiments of this application provide a computer storage medium storing a computer program, which, when executed by a processor, implements the steps of the method described above.

[0019] In this embodiment, the interactive flat panel includes a touch detection system, which comprises a piezoelectric sensor and an infrared touch module. The infrared touch module collects infrared stylus signals generated when an object touches the screen. Based on the generation time of the infrared stylus signal, a first moment is determined before the generation time. The piezoelectric sensor at this first moment undergoes signal reset processing. Based on the reset signal, the piezoelectric sensor collects sensor signals, and elastic wave signals and static force signals are determined. Touch feature data of the object is determined based on the elastic wave signals and / or static force signals. By determining the timing of piezoelectric sensor reset through the infrared stylus signals detected by the infrared touch module, signal reset is performed promptly before screen touch, ensuring that the accuracy of sensor signal acquisition is not affected by long-term error accumulation when an object touches the screen. Determining elastic wave signals and static force signals through sensor signals, and then determining touch feature data of the object based on static force signals and / or elastic force signals, improves the accuracy of touch feature data, thus enhancing the touch detection accuracy of the interactive flat panel. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1AThis is a schematic diagram of an office scenario illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0022] Figure 1B This is a teaching scenario diagram of a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0023] Figure 1C This is a schematic diagram of the touch area of ​​a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of an infrared touch system for a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of an interactive flat panel according to an embodiment of the present application, which provides a touch detection method for interactive flat panels.

[0026] Figure 4 This is a signal diagram of a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0027] Figure 5 This is a flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0028] Figure 6 This is a flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0029] Figure 7 A schematic diagram of sensor signals for a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0030] Figure 8 A schematic flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0031] Figure 9 A schematic flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0032] Figure 10 A schematic diagram of sensor signals for a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0033] Figure 11 This is a flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0034] Figure 12 A schematic flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0035] Figure 13 A schematic flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0036] Figure 14 A schematic flowchart illustrating a touch detection method for an interactive flat panel provided in an embodiment of this application;

[0037] Figure 15 This is a schematic diagram of the structure of a touch detection device for an interactive flat panel provided in an embodiment of this application;

[0038] Figure 16 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0040] Interactive whiteboards are frequently used to assist in various business scenarios, including work, study, and daily life. They are often mounted on walls in meeting rooms, classrooms, and other similar locations, or supported by movable stands for convenient use in different environments. Figure 1A As shown, in an office business scenario, users use the Interactive Flat Panel 100 to assist in meetings in the conference room, such as... Figure 1B As shown, in the teaching business scenario, users use the interactive whiteboard 100 to assist in class.

[0041] Interactive flat panels integrate one or more functions such as projectors, electronic whiteboards, screens, speakers, televisions, and video conferencing terminals. Depending on the version and functions, an interactive flat panel can consist of one physical entity or two or more physical entities.

[0042] like Figure 1A and Figure 1B As shown, these physical entities include screen 110, which can be used to display various information. The types of screen 110 may include LED (Light Emitting Diode) screen, OLED (Organic Light-Emitting Diode) screen, LCD (Liquid Crystal Display) screen, and so on.

[0043] Furthermore, depending on the business scenario (such as screen sharing, screen projection, screen merging, etc.), the interactive flat panel can establish a data connection with at least one external device. These external devices include, but are not limited to: mobile phones, laptops, USB (Universal Serial Bus) flash drives, screen sharing devices, tablets, desktop computers, and other interactive flat panels.

[0044] The communication methods for data connection between external devices and interactive smart panels can include USB connection, Internet, local area network, Bluetooth, Wi-Fi (Wireless Fidelity), and ZigBee (Zifeng protocol), etc.

[0045] Interactive flat panels can control the information displayed on the screen through touch technology, thereby realizing human-computer interaction. That is, a user interface (UI) is displayed on the screen, and the user touches the surface of the screen with a touch object. At this time, a positioning operation is performed to locate the position of the touch object on the screen and trigger the function of the corresponding position on the interface.

[0046] The object being touched includes at least one of the following:

[0047] Hands, stylus.

[0048] The hand can include the fingertips, knuckles, palm, and back of the hand. A stylus is generally a component provided by manufacturers of interactive flat panels. A stylus consists of a stylus tip and a stylus tail. The stylus tip and stylus tail can be made of the same or different materials.

[0049] The interactive whiteboard supports single-point touch, allowing users to perform touch operations on the screen surface using their hands or a stylus.

[0050] The interactive flat panel supports multi-touch, allowing a single user to use their hand and stylus simultaneously, with multiple fingers or styluses performing touch operations on the screen surface. Multiple users can also use their hand or stylus individually to perform touch operations on the screen surface.

[0051] It is understood that the surface of the screen is the side facing the user and displaying information to the external environment of the interactive flat panel. In order to protect the screen from scratches, a cover material (such as glass, PET, etc.) is set on the surface of the screen. Therefore, in the embodiments of this specification, the surface of the screen may refer to the surface of the cover glass of the screen.

[0052] In one type of touch technology, considering the large screen size of interactive flat panels, up to 55 inches or even hundreds of inches, an infrared touch system can be composed of electronic components such as infrared LEDs, infrared receivers, printed circuit boards, and infrared processors to provide touch technology support for the screen. For example... Figure 1C As shown, since the infrared sensor 120 is higher than the surface of the screen 110 (especially the glass cover), the infrared sensor 120 transmits light through a filter strip (also known as a filter). The filter strip is usually made by adding dyes to raw materials and then using injection molding or casting processes. The filter strip can transmit infrared light while filtering out other ambient light, thereby improving the signal-to-noise ratio of the infrared signal. Therefore, the infrared sensor 120 scans infrared signals on the surface of the screen 110 within a certain height range. Thus, the infrared sensor 120 forms a touch area in the vertical direction of the screen 110, with a height of H. Height H is relatively large, generally greater than 2 mm, and cannot be ignored. For infrared touch systems to implement the touch function of interactive tablets, when a touch object (such as a hand or pen) writes on the screen, the general process is to first press the touch object, move it when it touches the screen surface, and finally lift the touch object. Please refer to [link to relevant documentation]. Figure 2 From the perspective of infrared touch systems, infrared touch is divided into three stages: T0, IR1, and IR2. In the T0 stage, the object being touched has not yet entered the light grid area. In IR1, the object begins to block the infrared light. In IR2, the object makes contact with the glass. IR1 represents the actual time of blocking the light grid. However, IR2 is an estimated contact time with the screen based on empirical parameters such as area and pen stroke speed, making IR2 relatively inaccurate. When the user's pen stroke is slow, using the same set of empirical parameters will often result in the touch frame falsely reporting pen strokes.

[0053] In another touch technology, multiple elastic wave sensors are placed on the inside of the glass (as shown below). Figure 3 This is used to detect collision signals generated when a stylus collides with glass during writing. By analyzing the characteristics of the signal, the hardness of the writing material is determined. However, elastic wave sensors can only detect a portion of the elastic wave collision signal. Elastic wave signals are only generated when the stylus collides with the glass at a relatively high speed, so they cannot be used to detect the stylus's down and up signals. When the stylus collides with the glass with a slower force, the amplitude of the generated elastic wave signal is small (not reaching the trigger threshold or submerged in external noise), which may lead to missed signals. Furthermore, when a finger contacts the screen surface, due to the softness of human skin, there is no obvious elastic wave collision signal.

[0054] Based on the above-mentioned technical problems, this application provides a touch detection method for interactive tablets, which combines piezoelectric ceramic measurement of high-frequency elastic wave collision signals and low-frequency quasi-static force signals. By collecting elastic wave signals and static force signals by piezoelectric sensors, and using static force signals and / or elastic wave signals to generate touch feature data, the accuracy of touch feature data is improved.

[0055] Please see Figure 4 , Figure 4 The images show the signal diagrams generated after soft and hard objects collide with glass. The signal of the reciprocating vibration generated by the collision is called the elastic wave signal (high frequency 100Hz-20kHz), and the steady-state signal when the object contacts the screen is called the quasi-static force signal (extremely low frequency 0.01-10Hz). The fundamental principle of piezoelectric sensor force measurement technology is to integrate the charge generated by the piezoelectric sensor when it is subjected to external force using an integrating amplifier. During long-term integration, errors will inevitably accumulate due to sensor temperature, electromagnetic interference, or thermal noise of the operational amplifier itself, eventually resulting in baseline drift. Due to the technical characteristic of piezoelectric sensors measuring charge changes, the back-end operational amplifier circuit cannot measure charge for extended periods. Therefore, it can only measure force changes over short periods, which is called quasi-static force. The quasi-static force signal is only related to the magnitude of the force applied to the screen and is independent of the hardness or softness of the colliding object. The elastic wave signal is related to the material of the colliding object and the collision velocity.

[0056] Based on the detection characteristics of the piezoelectric sensor described above, the touch detection system in the interactive flat panel of this application includes a piezoelectric sensor and an infrared touch module. It is understood that due to the writing height, there is definitely no touch for a period of time before the infrared touch module detects the infrared pen-drop signal. Therefore, by setting a self-reset logic at the first moment before the generation of the infrared pen-drop signal, the piezoelectric sensor is reset, which solves the baseline drift problem of the piezoelectric sensor during long-term use. This also changes the force measurement process of the piezoelectric sensor from long-term force measurement to short-term force measurement, improving measurement accuracy. Using the method provided in this application, after signal reset, any material and speed of the touch object can be accurately detected as a static force signal when it contacts the screen, thus achieving accurate pressure sensing. Similarly, when writing ends and the touch object leaves the screen, a static force signal is also generated due to the disappearance of force. By analyzing the static force signal, the pen-drop and pen-lift signals (down and up signals) can be obtained. Furthermore, by analyzing the elastic wave signal, the material of the touch object and the collision speed (pen-drop speed) and other touch characteristics can be determined, achieving accurate confirmation of the touch object's touch characteristic data.

[0057] The touch detection method for interactive flat panels provided in this specification will be described in detail below with reference to specific embodiments.

[0058] Please see Figure 5 This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 5 As shown, the method in this application embodiment may include the following steps S101-S105.

[0059] S101, based on the infrared touch module, collects the infrared pen-drop signal generated when a touch object touches the screen;

[0060] In one embodiment, the interactive flat panel includes a touch detection system, which comprises a piezoelectric sensor and an infrared touch module. Exemplarily, at least one piezoelectric sensor is mounted on the screen of the interactive flat panel. The number and location of the piezoelectric sensors can be designed according to the screen size and shape, and are not specifically limited. The sensitive element of the piezoelectric sensor is made of a piezoelectric material (e.g., piezoelectric ceramic). When the piezoelectric material is subjected to force, a charge is generated on its surface. This charge can be detected and converted into a voltage output by a piezoelectric ceramic static force detection system composed of a charge amplifier. Exemplarily, the piezoelectric sensor includes a metal substrate, a piezoelectric layer, and an insulating layer. Optionally, the touch detection system may further include a charge amplifier connected to the piezoelectric sensor for detecting the charge signal generated by the piezoelectric sensor and converting it into a voltage signal output. Optionally, the touch detection system may further include a processing unit connected to the piezoelectric sensor for receiving a reset command and controlling the piezoelectric sensor to perform signal reset processing according to the reset command.

[0061] An infrared touch module mainly consists of an infrared transmitter, a receiver, and corresponding circuitry. Its working principle involves mounting an array of infrared transmitters and receivers on the device's surface, forming an infrared grid. When a finger or other object touches or approaches the touch surface, it interrupts or reflects a portion of the infrared signal, thereby triggering corresponding control or operation. Please refer to [further details omitted]. Figure 2 Infrared lights form an infrared grid on the screen surface. When a touch object blocks the grid, the infrared lights report an IR1 signal. Simultaneously, the infrared lights predict the time when the touch object touches the screen based on the IR1 signal and report an IR down (IR2) signal at that time. Specifically, IR2 or IR1 can be designated as the infrared touch signal.

[0062] S102, determine the first moment before the generation of the infrared pen-drop signal, and perform signal reset processing on the piezoelectric sensor at the first moment;

[0063] In one embodiment, the generation time of the infrared pen-drop signal is also the time when the infrared pen-drop signal is detected. It is understood that when the infrared touch module detects the infrared pen-drop signal, it indicates that the object is about to touch or has already touched the screen. Therefore, there will definitely be no touch for a certain period of time before the generation time of the infrared pen-drop signal. This period can be much smaller than the temperature drift time of the piezoelectric sensor (10s) but larger than the reporting delay time of the infrared touch module (milliseconds). Based on the generation time and a preset time, a first moment is determined, which is the moment determined by subtracting the preset time before the generation time. The signal amplitude of the piezoelectric sensor for this first preset time is restored to its initial state, which can be a set zero value. For example, the processing unit in the screen (e.g., a microcontroller unit, MCU) stores sensor output signals for a period of time. Based on the determined first moment, the signal corresponding to that moment is found in the stored sensor output signals, and the signal amplitude at that moment is reset, thereby improving the accuracy of the sensor signals acquired after the first moment.

[0064] The preset time can be set, for example, to approximately 1 second, so the first moment is the moment 1 second prior to the generation time. The advance time can be set differently depending on the selected infrared pen-drop signal. The infrared pen-drop signal can be a signal triggered when the touched object blocks the infrared light grid (see attached diagram). Figure 2 The IR1 in the image or the pen-dropping signal inferred from the time the touch object blocks the infrared light grid (corresponding to the attached image). Figure 2 (IR2 in the example). Since IR1 was acquired earlier than IR2, if the IR1 signal is used to determine the timing of the reset operation, the advance time should be shorter than that of IR2, or the preset advance time can be set directly to zero.

[0065] S103, acquire the sensor signal collected by the piezoelectric sensor after signal reset processing;

[0066] In one embodiment, the baseline of the piezoelectric sensor is accurate for a period of time after the signal reset process, and the sensor signal collected by the piezoelectric sensor is also accurate during this period. The sensor signal collected by the piezoelectric sensor after the first moment is continuously acquired.

[0067] S104, determines elastic wave signal and static force signal based on sensor signal;

[0068] In one embodiment, based on the different frequency characteristics of the elastic wave signal and the static force signal, the sensor signal is separated into a high-frequency elastic wave signal and a low-frequency quasi-static force signal. Specifically, the frequency of the elastic wave signal is typically between 100Hz and 20kHz, while the frequency of the quasi-static force signal is typically between 0.01 and 10Hz. Therefore, by analyzing the frequency of the sensor signal, the elastic wave signal and the quasi-static force signal can be determined. It is understood that the acquisition and separation of the sensor signal are almost simultaneous; that is, as soon as the piezoelectric sensor acquires the sensor signal, it is immediately separated by a processor (e.g., an MCU (Microcontroller Unit)) for real-time analysis to generate touch feature data.

[0069] It should be noted that traditional charge amplifiers include a feedback resistor Rf and a feedback capacitor Cf connected in parallel. During operation, the feedback capacitor Cf accumulates the charge generated by the piezoelectric sensor. Traditional charge amplifiers generate significant noise during operation, and the amplifier continuously integrates this noise, causing the accumulated charge in the feedback capacitor Cf to gradually dissipate. This results in a change in the output voltage signal. After the voltage generated by the piezoelectric sensor rises sharply from the bias voltage, the output voltage gradually decreases as the accumulated charge in the feedback capacitor Cf dissipates. When the sensor detects that the touchpad's pressed area has been released, the voltage generated by the piezoelectric sensor drops sharply, sometimes even falling below the bias voltage. This affects the accuracy of the subsequent measurement results from the piezoelectric sensor, causing deviations in the measured quasi-static force signal.

[0070] Therefore, in one embodiment, a static force signal can be obtained by processing the static force signal using a preset signal compensation algorithm.

[0071] It is understood that the piezoelectric sensor used in the embodiments of this specification can be a piezoelectric sensor signal detection system including a processing unit and a charge amplifier. Specifically, when the piezoelectric sensor detects that the pressing area of ​​the touchpad is pressed, a differential voltage signal is generated and input to the charge amplifier. The charge amplifier receives the differential voltage signal input from the piezoelectric sensor. When the output voltage at its output terminal is lower than the bias voltage, it receives a reset signal applied from the processing unit, restoring the output voltage at the output terminal to the bias voltage. The processing unit uses a preset discharge compensation algorithm to compensate the output voltage at the output terminal of the charge amplifier, obtaining the compensated output voltage. This avoids noise generated by the charge amplifier during actual operation from affecting the measurement results of the piezoelectric sensor, improving the accuracy of static force signal acquisition.

[0072] S105, determine the touch feature data of the object being touched based on elastic wave signals and / or static force signals.

[0073] In one embodiment, the separated elastic wave signal and static force signal can be used separately to determine the touch feature data of the touched object, or the elastic wave signal and static force signal can be combined to determine the touch feature data of the touched object. The elastic wave signal and static force signal obtained by the above acquisition method are more accurate, thereby improving the accuracy of the touch feature data. For example, the touch feature data may include touch pressure, pen placement time, pen lifting time, and writing material. In one feasible implementation, the writing material and collision speed of the touched object are determined based on the elastic wave signal. In another feasible implementation, the change of force applied to the screen is determined based on the static force signal, thereby determining the touch start and end time (pen placement time and pen lifting time) of the touched object. In addition, the magnitude of the force currently applied to the screen can be detected based on the static force signal to adjust the thickness of the writing or to identify force-sensitive finger interaction events. In yet another feasible implementation, the pen placement time is determined based on the static force signal, and the writing material of the touched object is determined based on the elastic wave signal acquired after the pen placement time.

[0074] In this embodiment, by acquiring the infrared pen-drop signal generated when a touch object touches the screen through an infrared touch module, and determining the first moment before the generation of the infrared pen-drop signal, the piezoelectric sensor at the first moment is reset. This can solve the baseline drift problem of the piezoelectric sensor during long-term use, improve the measurement accuracy of the piezoelectric sensor, and thus acquire accurate sensor signals when a touch object touches the screen, thereby improving the accuracy of the touch feature data of the touch object determined based on the static force signal and / or elastic force signal obtained from the piezoelectric sensor.

[0075] Please see Figure 6 This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 6 As shown, the method in this application embodiment may include the following steps S201-S211.

[0076] S201, based on the infrared touch module, collects the occlusion signal generated when the touched object occludes the infrared light grid, and uses it as the infrared pen-drop signal;

[0077] In one embodiment, when the object being touched blocks the infrared light grid, the infrared touch module can collect the blocking signal. It is understood that the object must block the infrared light grid before touching the screen surface. Therefore, the blocking signal can be identified as the infrared pen-drop signal detected by the infrared touch module. This infrared pen-drop signal is not a real pen-drop time, but has a certain deviation.

[0078] S202, based on the infrared touch module, collects the occlusion signal generated when the touched object occludes the infrared light grid;

[0079] In one embodiment, the occlusion signal generated when the object being touched blocks the infrared light grid can be collected first through the infrared touch module. Then, the touch signal can be determined based on the occlusion signal and identified as an infrared pen-dropping signal.

[0080] S203, based on the occlusion signal, predicts the touch signal generated when the touch object touches the screen, and uses it as the infrared pen placement signal;

[0081] In one embodiment, based on the occlusion signal, the time it takes for the object to touch the screen can be further predicted, and a touch signal can be generated, which is then used as an infrared pen-drop signal. Specifically, after the occlusion signal is acquired, the contact time between the object and the screen is estimated based on empirical parameters such as the occlusion area and the pen-drop speed, and a touch signal is generated.

[0082] It should be noted that steps S201 and S202-S203 are parallel schemes, and either one can be executed. Depending on the selected infrared pen-drop signal, the reset advance time of the piezoelectric sensor can also be different. Judgment logic can be pre-written in the processor. For example, when the infrared pen-drop signal is generated when a touch object blocks the infrared light grid, a first advance time is set, and the first moment is determined based on the first advance time. Alternatively, when the infrared pen-drop signal is generated when a predicted touch object touches the screen, a second advance time is set, and the first moment is determined based on the second advance time.

[0083] S204, determine the first moment before the generation of the infrared pen-drop signal, and perform signal reset processing on the piezoelectric sensor at the first moment;

[0084] In one embodiment, after determining the infrared pen-drop signal, a first moment is determined based on the generation time of the infrared pen-drop signal. Optionally, the first moment can also be the generation time. Specifically, when the infrared pen-drop signal is triggered by the touch object blocking the infrared light grid, the touch object has not actually touched the screen yet, so the first moment can be determined as the generation time, and the sensor output signal at that moment is reset. For example, the processing unit in the screen (e.g., a microcontroller unit, MCU) stores sensor output signals for a period of time. Based on the determined first moment, the signal corresponding to that moment is found in the stored sensor output signals, and the signal amplitude at that moment is reset, thereby improving the accuracy of sensor signals acquired after the first moment.

[0085] S205, acquire the sensor signal collected by the piezoelectric sensor after signal reset processing;

[0086] Specifically, please refer to step S103 in the above embodiment of the specification, which will not be repeated here.

[0087] Please see Figure 7 , Figure 7 This application provides a schematic diagram of sensor signals for a touch detection method for an interactive flat panel, as shown in this embodiment. Figure 7 The solid blue line represents the amplitude change trend of the sensor signal. At the moment before the infrared pen-drop signal, the piezoelectric sensor receives a reset signal, thereby setting the signal amplitude to zero at that moment. Figure 7 The blue dashed line represents the amplitude threshold of the sensor signal. This amplitude threshold is set based on the minimum test accuracy of the piezoelectric sensor. When the sensor signal amplitude is lower than this threshold, it indicates that there is pressure from touching the screen, generating a target pen-drop signal.

[0088] S206, based on the cutoff frequency, separates the elastic wave signal and the quasi-static force signal from the sensor signal;

[0089] In one embodiment, the sensor signal is separated according to the cutoff frequency to obtain an elastic wave signal and a quasi-static force signal. For example, depending on the detection characteristics of the piezoelectric sensor, the cutoff frequency can be selected between 10 Hz and 100 Hz. A single cutoff frequency can be set, for example, 50 Hz; then, the frequency above 50 Hz is the elastic wave signal, and the frequency below 50 Hz is the quasi-static force signal. Alternatively, cutoff frequencies can be set separately for the high-pass and low-pass signals. For example, the cutoff frequency of the high-pass signal can be set to 100 Hz, and the cutoff frequency of the low-pass signal to 10 Hz. This means that the voltage signal above 100 Hz is identified as the elastic wave signal, and the voltage signal below 10 Hz is identified as the static force signal.

[0090] Optionally, in one embodiment, the separation of the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency includes:

[0091] S2061, the sensor signal is input into the analog high-pass filter and the analog low-pass filter respectively to separate the analog elastic wave signal and the analog static force signal;

[0092] Specifically, analog filters are used to separate the voltage signal. The analog high-pass filter and analog low-pass filter are set based on cutoff frequencies. The analog low-pass filter allows signals below the cutoff frequency to pass through while attenuating signals above the cutoff frequency. The analog high-pass filter allows signals above the cutoff frequency to pass through while attenuating signals below the cutoff frequency. The analog high-pass filter can separate the analog elastic wave signal, and the analog low-pass filter can separate the analog static force signal.

[0093] S2062 uses an amplifier circuit to amplify the analog elastic wave signal and the analog quasi-static force signal respectively, to obtain the amplified analog elastic wave signal and the amplified analog static force signal;

[0094] Specifically, an amplifier circuit is used to amplify the separated analog electrical signal to near the range of the analog-to-digital converter (ADC) so that it can be converted into a digital signal for subsequent processing.

[0095] S2063, based on an analog-to-digital converter, converts amplified analog elastic wave signals and amplified analog static force signals into elastic wave signals and static force signals.

[0096] Specifically, after amplifying the simulated elastic wave signal and the simulated static force signal respectively, the signal quality of each channel can be ensured. Then, the analog-to-digital converter is used to convert them into digital signals that can be processed by a computer or microcontroller to obtain the elastic wave signal and the static force signal.

[0097] Please see Figure 8 , Figure 8 This application provides a flowchart illustrating a touch detection method for an interactive flat panel. The piezoelectric sensor outputs a charge signal, which is converted into a voltage signal by a charge amplification circuit (high input impedance amplifier). This voltage signal contains a high-frequency elastic wave signal and a low-frequency quasi-static force signal. Analog high-pass / low-pass filters are used to separate the analog elastic wave signal and the analog quasi-static force signal from the original signal. The separated analog electrical signals are amplified to near the range of an analog-to-digital converter (ADC) using an amplification circuit, and the ADC is used for signal acquisition to obtain the elastic wave signal and the quasi-static force signal. The algorithm then performs signal compensation processing on the quasi-static force signal, corrects the bias, and fits it to obtain the static force signal. The advantage of this scheme is that it separates, amplifies, and acquires the two signals separately, ensuring the signal quality of each channel and reducing the likelihood of saturation distortion due to excessive signal strength or quantization distortion due to insufficient signal strength.

[0098] Optionally, in one embodiment, the separation of the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency includes:

[0099] S2064 converts sensor signals into digital signals via an analog-to-digital converter;

[0100] In one embodiment, the sensor signal is directly converted into a digital signal via an analog-to-digital converter.

[0101] S2065 inputs the digital signal into the high-pass digital filter and the low-pass digital filter respectively to separate the elastic wave signal and the quasi-static force signal;

[0102] Specifically, digital signals are filtered and separated using high-pass and low-pass digital filters, which are set based on cutoff frequencies. It is understandable that the cutoff frequencies can be adjusted according to the signal type; for example, digital signals and voltage signals may have different cutoff frequencies, allowing for adaptive adjustment of the cutoff frequencies.

[0103] Please see Figure 9 , Figure 9 This application provides a flowchart illustrating a touch detection method for an interactive flat panel, as shown in the embodiments below. Figure 9 As shown, the sensor signal can be a charge signal, which is then processed by a charge amplification circuit to obtain a voltage signal. This voltage signal is then directly processed by a high-pass digital filter and a low-pass digital filter to obtain the elastic wave signal and the quasi-static force signal. The advantage of this scheme is that it can use relatively simple analog circuits to complete the entire operation, and the order of the digital filter is more easily made higher than that of the analog filter, resulting in a cleaner separated signal. Afterwards, the signal enters the algorithm for further processing, and the quasi-static force signal is compensated to obtain the static force signal.

[0104] S207, Perform signal compensation processing on the static force signal to obtain the static force signal;

[0105] In one embodiment, based on the positive piezoelectric effect of the piezoelectric sensor, when the piezoelectric sensor is deformed under force, a certain amount of charge is generated. That is, the sensor signal collected in one embodiment is a charge signal, and the charge amplification circuit is used to amplify the tiny charge generated by the piezoelectric sensor. Therefore, the sensor signal is converted into a voltage signal by the charge amplification circuit connected to the piezoelectric sensor for subsequent processing.

[0106] During actual circuit operation, the charge amplifier generates significant noise, which is continuously integrated, causing fluctuations in its output voltage. This is particularly problematic when the piezoelectric sensor detects quasi-static force. When the piezoelectric sensor detects pressure on the touchpad's pressing area, the output voltage initially rises sharply from the bias voltage. However, this voltage doesn't remain constant until the pressure is released. As the charge accumulated in the feedback capacitor Cf is gradually discharged, the output voltage decreases. At the instant the piezoelectric sensor detects the pressure being released, the resulting negative charge pulls the charge amplifier's output voltage below the bias voltage, causing a sudden drop. This leads to inaccurate quasi-static force signal acquisition over extended periods. To address this issue, a pre-defined discharge compensation algorithm (signal compensation processing) is used to compensate the output voltage of the charge amplifier, restoring it from below the bias voltage. This corrects the bias in the piezoelectric sensor's direct acquisition of the quasi-static force signal, yielding a static force signal.

[0107] S208, Determine the touch feature data of the touched object based on elastic wave signals and / or static force signals;

[0108] For details, please refer to the description of step S105 in the above embodiment of the specification, which will not be repeated here.

[0109] S209, based on the infrared touch module to collect the infrared pen lifting signal generated when the touched object leaves the screen;

[0110] In one embodiment, the infrared touch module can also collect an infrared lift-up signal generated when the touch object leaves the screen. It is understood that when the infrared light grid changes from being blocked to being unblocked, it indicates that the touch object has left the screen surface, and at this time, the infrared touch module can generate an infrared lift-up signal. Similarly, this infrared lift-up signal can be triggered when the touch object leaves the light grid, and therefore, the infrared lift-up signal has a certain delay compared to the actual time the touch object leaves the screen. The actual lift-up signal can be obtained from static force signal analysis. When the touch object leaves the screen, the pressure on the screen surface disappears, and this pressure change is collected as a static force signal by the piezoelectric sensor.

[0111] S210, determine the second moment after the generation of the infrared pen lifting signal, and perform signal reset processing on the piezoelectric sensor at the second moment.

[0112] In one embodiment, after the infrared pen-lift signal is reported, the sensor signal is reset to zero again after a fixed period of time to prevent temperature drift from causing the sensor signal to exceed its range and affecting the signal detection of the second pen stroke. It should be noted that after the pen is lifted, there may be some screen vibration. The piezoelectric sensor signal reset should only be performed after the vibration disappears. Typically, the vibration disappears within the time interval between detecting the actual pen-lift signal and detecting the infrared pen-lift signal. Therefore, the signal reset can be performed at the moment the infrared pen-lift signal is generated. To ensure that the vibration completely disappears and to make the reset operation more accurate, a waiting time, such as 1 second, can be set. The second moment after the generation of the infrared pen-lift signal is defined as the second moment, and the piezoelectric sensor signal reset is performed at this second moment.

[0113] Please see 10. Figure 10 This application provides a schematic diagram of sensor signals for a touch detection method for an interactive flat panel, as shown in this embodiment. Figure 10 The solid blue line represents the amplitude change trend of the sensor signal. At the moment before the infrared pen-drop signal, the piezoelectric sensor receives a reset signal, thereby setting the signal amplitude to zero at that moment. Figure 10 The blue dashed line represents the amplitude threshold of the sensor signal. This threshold is set based on the minimum testing accuracy of the piezoelectric sensor. When the sensor signal amplitude is below this threshold, it indicates that there is pressure applied to the screen, generating a target (actual) pen-drop signal. When the sensor signal amplitude changes from below the threshold to above the threshold, a target (actual) pen-lift signal is generated. Subsequently, as the touched object leaves the infrared light grid, the infrared touch module generates an infrared pen-lift signal. A reset signal can be sent to the piezoelectric sensor after the infrared pen-lift signal is generated to reset the piezoelectric sensor.

[0114] In this embodiment, an infrared touch module collects an occlusion signal generated when a touch object blocks an infrared light grid, which is used as an infrared pen-drop signal. Alternatively, the touch signal is further predicted based on the occlusion signal and determined as an infrared pen-drop signal. A first moment is determined based on the generation time of the infrared pen-drop signal. The piezoelectric sensor at the first moment is then reset. The sensor signal collected by the piezoelectric sensor after the signal reset is obtained. The sensor signal is converted into a voltage signal via a charge amplification circuit. Since there is a significant difference in frequency distribution between the elastic wave signal and the quasi-static force signal, the sensor output signal can be separated using an analog filter or a digital filter based on the cutoff frequency to obtain the elastic wave signal and the static force signal. The touch feature data of the touch object is determined based on the elastic wave signal and / or the static force signal. The infrared pen-lift signal generated when the touch object leaves the screen is collected by the infrared touch module. A second moment is determined after the generation time of the infrared pen-lift signal. The piezoelectric sensor at the second moment is then reset to avoid error accumulation that causes the sensor signal to exceed its range, thus ensuring the measurement effect of the piezoelectric sensor.

[0115] Please see Figure 11 This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 11 As shown, the method in this application embodiment may include the following steps S301-S302.

[0116] S301, when a static force signal is detected to meet the first signal range after the infrared pen-drop signal, a target pen-drop signal is generated, and the generation time of the target pen-drop signal is determined as the writing pen-drop time.

[0117] In one embodiment, when the touch feature data is the writing start time and writing lift time, a target writing start signal can be generated when a static force signal that meets the first signal range is detected after the infrared writing start signal, and the generation time of the target writing start signal is determined as the writing start time.

[0118] It's understandable that elastic wave signals are high-frequency signals, generated only during "hard-on-hard" collisions. The frequency characteristics of elastic wave signals can be used to determine the material information of the colliding object. However, because the frequency band of elastic wave signals overlaps with the frequency band of external noise, they are easily interfered with by external noise, such as clapping signals or interference signals from the tablet's built-in speakers. When a user gently places a pen, no elastic wave signal generated by the collision can be found. Furthermore, finger contact with the screen is considered "soft-on-hard," making it difficult to detect elastic wave signals (the signal amplitude is very small). Quasi-static force signals, on the other hand, are extremely low-frequency signals, generating corresponding quasi-static force signals regardless of whether it's a "soft-on-hard" or "hard-on-hard" collision. Moreover, the frequency band of static force signals is generally between 0.01Hz and 10Hz, which does not overlap with common noise frequency bands, so it is largely unaffected by external noise. Using static force signals to determine the pen placement signal is an absolutely accurate method. Therefore, if a static force signal meeting the first signal range is collected after the infrared pen placement signal, it indicates that the object touched the screen. The first signal range refers to the effective signal range of the sensor signal. It can be set according to the detection accuracy of the piezoelectric sensor, the sensor polarity, and the signal processing method. For example, slight vibrations in the sensor itself may generate a certain signal noise floor. Therefore, the first signal range needs to be outside this signal noise floor to identify the sensor signal actually generated by the touch operation. For instance, the first signal range can be from a certain threshold to the upper limit of the signal amplitude, such as (-0.0005, -1.65).

[0119] S302, when a static force signal that meets the second signal range is detected after the target pen-dropping signal, a target pen-lifting signal is generated, and the generation time of the target pen-lifting signal is determined as the writing pen-lifting time;

[0120] In one embodiment, when the piezoelectric sensor detects that the touchpad's pressing area is pressed, the signal generated by the piezoelectric sensor rises sharply and remains elevated for a period of time until the touchpad (screen)'s pressing area is released, at which point the signal generated by the piezoelectric sensor drops sharply. Furthermore, according to the theory of action and reaction forces, the force during pressing is equal to the force during releasing, so the absolute values ​​of the charges generated during pressing and releasing are equal, but in opposite directions. Since the capacitance of the piezoelectric sensor is fixed, according to the formula between voltage U and charge Q: U = Q / C, pressing and releasing result in equal voltage values ​​generated by the piezoelectric sensor, but in opposite directions. The voltage (charge) generated by the piezoelectric sensor can be detected by a charge amplifier.

[0121] Similarly, when a static force signal is detected after the target pen-drop signal that meets the second signal range, such as (0.0005, 1.65), it indicates that the object being touched has left the screen, generating a target pen-lifting signal.

[0122] This touch detection system design eliminates the need for the structure to maintain a specific height between the infrared light grid and the screen, thus improving the accuracy of the infrared touch module's touch time prediction. Instead, it uses static force signals to collect pen lift and put-down signals, reducing the requirements for structural consistency. It also eliminates the need to ensure the rigidity of the glass (if the glass is too thin, it is prone to vibration during writing, obstructing the light grid). This allows for a reduction in the overall weight of the device.

[0123] In this embodiment, the writing start time and writing lift time can be determined by static force signal analysis. Since infrared writing start signal recognition is inaccurate, the infrared writing start signal is used as a reference time point. If a static force signal satisfying a first signal range is detected after the infrared writing start signal, the target writing start signal is determined based on the static force signal, and the writing start time is determined based on the target writing start signal. When the pen is lifted, the piezoelectric sensor generates a static force signal with the opposite value to that at the time of writing start. Therefore, if a static force signal satisfying a second signal range is detected after the target writing start signal, it can be determined as the target lifting signal. The generation time of the target lifting signal is determined as the writing lift time. Since the piezoelectric sensor is reset, the accuracy of the collected static force signal can be guaranteed, and the static force signal is not easily affected by external noise. Therefore, accurate writing start time and writing lift time can be collected in this way.

[0124] Please see Figure 12 This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 12 As shown, the method in this application embodiment may include the following step S401.

[0125] S401 determines writing pressure based on static force signals;

[0126] In one embodiment, the touch feature data is writing force, i.e., touch pressure. The static force signal is positively correlated with the pressure value of the pressing operation. This can be achieved by testing with a known force and recording the corresponding static force signal to generate a mapping relationship between the static force signal and the force value. Therefore, after acquiring the static force signal, it can be converted into the corresponding force value, i.e., writing force. It is understood that the above-mentioned mapping conversion of writing force can be performed after the target pen stroke signal is detected, thereby reducing unnecessary signal processing.

[0127] Alternatively, the static force signal with the largest absolute value can be identified from the static force signals, and the writing force can be determined based on the static force signal with the largest absolute value.

[0128] Optionally, the force recognition model can be trained using networks such as CNN (Convolutional Neural Networks), RNN (Recurrent Neural Networks), and DNN (Deep Neural Networks). This force recognition model requires pre-training. Training data can be obtained by having different experimenters touch the touchscreen with specified force levels, generating static force signals at multiple locations fed back by the piezoelectric sensor. For example, this could be a peak value from each output static force signal. These peak values ​​are then correlated with the touch force and used as input for model training to obtain the force recognition model. After the force model is trained, the collected static force signals can be input into the force recognition model to determine the corresponding writing force.

[0129] Furthermore, analyzing writing pressure through static force signals can solve the problem of foreign objects obstructing touch on the tablet surface, identifying whether the obstruction is due to human touch or a foreign object. It's understandable that human / stylus touch has a certain pressure, and this pressure cannot be guaranteed to be completely consistent. Some obstructions, such as sticky notes or erasers, do not apply a varying force to the screen surface. In this case, the magnitude and variation of writing pressure can be used to identify non-touch obstructions. Further, writing pressure can also be used to adjust the thickness of the writing strokes, displaying different handwriting effects on the interactive tablet based on the user's selected type and the preset mapping between writing pressure and stroke thickness. Optionally, writing pressure can also be used to determine force-sensitive finger interaction events, thereby enriching the touch interaction effects of the interactive tablet.

[0130] In this embodiment, the writing force can be determined using a static force signal. Because the piezoelectric sensor is reset at the first moment, an accurate static force signal can be acquired. Furthermore, based on the characteristic that the magnitude of the static force signal is proportional to the touch force, the touch force, i.e., the writing force, can be accurately determined.

[0131] Please see Figure 13 This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 13 As shown, the method in this application embodiment may include the following steps S501-S502.

[0132] S501, acquire the first signal characteristics of the elastic wave signal;

[0133] In one embodiment, the different materials of the touch object affect the propagation speed of the elastic wave due to their varying densities and elastic moduli. For example, hard materials (such as metals) cause the elastic wave to propagate faster, while soft materials (such as rubber or fabric) cause it to propagate slower. Furthermore, the materials of the touch object have different absorption capacities for elastic waves; soft materials generally result in stronger signal attenuation, while hard materials cause less attenuation. Different materials may lead to different frequency response characteristics. Some materials exhibit significant resonance effects or attenuation characteristics within specific frequency ranges. The material of the touch object may also affect the waveform of the signal; for example, soft objects may result in a smoother signal, while hard objects may produce more drastic changes. Therefore, the elastic wave signal acquired by the piezoelectric sensor after signal reset processing can be analyzed to obtain its primary signal characteristics, such as amplitude, frequency, propagation speed, and attenuation.

[0134] S502, determine the writing material of the touch object based on the first signal characteristics.

[0135] In one embodiment, the writing material of the touch object is determined based on the first signal characteristics of the elastic wave signal. Common touch object materials, such as plastic, metal, rubber, and glass, all have different elastic wave signal characteristics. The elastic wave signals of touch objects of different materials can be calibrated using a large amount of experimental data. A model can be trained using machine learning or signal processing methods to determine the material of the touch object based on the acquired elastic wave signal characteristics (such as signal amplitude, frequency, and propagation speed). For example, algorithms such as Support Vector Machine (SVM), decision trees, and neural networks can be used to distinguish different materials based on the feature values ​​of the elastic wave signal.

[0136] Optionally, the absolute and relative values ​​of energy at characteristic frequency points in wavelet time-frequency analysis can be obtained by combining the time-domain and frequency-domain information of the elastic wave signal (including time points that exceed the set signal-to-noise ratio threshold in the time domain), and the starting point of the elastic wave signal can be determined based on this. Then, material identification can be performed based on the signal after the starting point.

[0137] In this embodiment, the writing material of the touched object can be analyzed using elastic force signals. By performing feature analysis on the elastic force signals to obtain first signal features, and then performing feature matching based on these first signal features, the writing material of the currently touched object can be determined. Since the elastic wave signal being analyzed is collected after signal reset processing, when the touched object has not yet touched the screen, the elastic wave signal collected during this period can capture the changes in elastic waves generated when the touched object contacts the screen, thereby improving the accuracy of the touch object material analysis.

[0138] Please see Figure 14This is a flowchart illustrating a touch detection method for an interactive flat panel, as provided in an embodiment of this application. Figure 14 As shown, the method in this application embodiment may include the following steps S501-S502.

[0139] S601, when a static force signal that meets the first signal range is detected after the infrared pen-drop signal, a target pen-drop signal is generated;

[0140] For details, please refer to the description of step S301 in the above embodiment of the specification, which will not be repeated here.

[0141] S602, acquire the target elastic wave signal generated within a preset time after the target pen-drop signal;

[0142] In one embodiment, the touch feature data is the writing material. Elastic wave signals are high-frequency signals that are only generated during a "hard-on-hard" contact. The material information of the colliding object can be determined by the frequency characteristics of the elastic wave signal. However, because the frequency band of the elastic wave signal overlaps with the frequency band of external noise, the elastic wave signal is also easily interfered with by external noise, such as clapping signals or interference signals emitted by the tablet's built-in speakers. Therefore, when the timing of the pen touch is unclear and there is some external noise, it is easy to not find the elastic wave signal generated when the finger touches the surface, making it impossible to make a judgment.

[0143] Therefore, to accurately locate the target elastic wave signal generated by the collision with the object during writing, the start time of the signal search can be determined based on the writing placement signal. Within a preset time after the start time, the elastic wave signal with the largest energy change is searched as the target elastic wave signal. Specifically, a sliding window method can be used. After the start time, windows are slid one by one according to a preset sliding window length, and the peak value is calculated for each window. The maximum value and its corresponding position are output from the calculation results of all windows, and the elastic wave signal with the maximum peak value is taken as the target elastic wave signal. Then, the writing material is determined based on this target elastic wave signal. Optionally, all elastic wave signals within the sliding window with the maximum peak value can also be determined as the target elastic wave signal.

[0144] Typically, within five milliseconds after the writing signal, a segment of elastic wave signal with the largest energy change will appear. By accurately determining the writing signal and searching only for the elastic wave signal that changes abruptly after and is adjacent to the writing signal, the signal search time can be shortened, thus allowing for faster identification of the target elastic wave. This, in turn, enables touch display based on the identified writing material, improving the efficiency of writing recognition.

[0145] When a soft object touches the screen, it does not generate a noticeable elastic wave signal. Therefore, after obtaining an accurate pen-drop signal through quasi-static force signals, an elastic wave signal can be searched for after the pen-drop signal. If no elastic wave signal is found, it indicates that the current situation is a "soft-on-hard" contact, usually a finger.

[0146] S603, determine the writing material of the touch object based on the second signal characteristics of the target elastic wave signal.

[0147] In one embodiment, after acquiring the target elastic wave signal, the writing material of the touch object can be determined based on the second signal characteristics of the target elastic wave signal.

[0148] The signal characteristics may include time-domain based features or transform-domain based nonlinear features, such as peak points, the interval between the i-th (i is a positive integer) peak point and the (i+1)-th peak point, zero-crossing rate, short-time energy, short-time autocorrelation function, short-time average amplitude difference, short-time power spectral density, spectral entropy, fundamental frequency, resonance peaks, etc. This embodiment does not limit these features.

[0149] The feature information corresponding to touch objects of different materials is analyzed, and one or more rules that can distinguish different materials are set under the dimension of feature information. For example, feature information is greater than a certain threshold, feature information is within a certain range, the ratio between feature information is less than a certain threshold, and so on.

[0150] It is understandable that the harder the material of the object being touched, the higher the signal frequency and the larger the signal quantity; the softer the material, the lower the signal frequency and the smaller the signal quantity. Therefore, by analyzing the second signal characteristics of the target elastic wave signal, the material of the object being touched, i.e. the writing material, can be determined.

[0151] In one feasible implementation, before the interactive flat panel leaves the factory, or in situations such as when a user-defined touch object is touched on the screen surface, elastic wave signals generated by the touch object with a marked material can be collected as samples. These samples can be stored in a local database of the interactive flat panel. When a touch object touches the screen surface of the interactive flat panel, the database can be used to search for samples with marked materials. Features (such as spectrum) are extracted from each sample, and signal features (such as spectrum) are extracted from the target elastic wave signal. The features of the target elastic wave signal are then matched with the features of each sample (such as calculating the similarity between spectra). If the features of the target elastic wave signal successfully match the features of a certain sample (such as the highest similarity, which is greater than or equal to a threshold), it can be determined that the touch object belongs to a preset material, and the touch effect corresponding to that material can be displayed on the interactive flat panel. For example, when it is identified as a pen tip, writing marks are displayed on the interactive flat panel; when it is identified as a pen tail, existing writing is erased on the interactive flat panel.

[0152] In this embodiment of the application, the writing time can be obtained by analyzing the static force signal. By searching for the target elastic wave signal within a preset time after the writing time, the elastic wave signal generated by the touch collision can be accurately determined. Then, the writing material identification can be improved based on the second signal characteristics of the target elastic wave signal.

[0153] The following will be combined with the appendix Figure 15 This application provides a detailed description of the touch detection device for interactive flat panels provided in its embodiments. It should be noted that the appendix... Figure 15 The touch detection device for interactive flat panels described herein is used to perform the functions described in this specification. Figures 5-14 The methods shown in the embodiments are illustrated for ease of explanation, showing only the parts relevant to the embodiments of this application. For specific technical details not disclosed, please refer to this specification. Figures 5-14 The example shown.

[0154] Please see Figure 15 This diagram illustrates a structural schematic of a touch detection device for an interactive flat panel, provided in an exemplary embodiment of this specification. The touch detection device for the interactive flat panel can be implemented as all or part of a device through software, hardware, or a combination of both. The device 1 includes an infrared module 11, a reset module 12, a data acquisition module 13, a signal separation module 14, and a recognition module 15.

[0155] Infrared module 11 is used to collect infrared pen signals generated when a touch object touches the screen based on the infrared touch module;

[0156] The reset module 12 is used to determine the first moment before the generation of the infrared pen-drop signal and to perform signal reset processing on the piezoelectric sensor at the first moment.

[0157] Acquisition module 13 is used to acquire the sensor signal acquired by the piezoelectric sensor after signal reset processing;

[0158] Signal separation module 14 is used to determine elastic wave signal and static force signal based on sensor signal;

[0159] The identification module 15 is used to determine the touch feature data of the touch object based on elastic wave signals and / or static force signals.

[0160] Optionally, the touch feature data are the writing start time and the writing lift time. The recognition module 15 is specifically used to generate a target writing start signal when a static force signal that meets the first signal range is detected after the infrared writing start signal, and to determine the generation time of the target writing start signal as the writing start time.

[0161] When a static force signal that meets the second signal range is detected after the target pen-falling signal, a target pen-lifting signal is generated, and the generation time of the target pen-lifting signal is determined as the writing pen-lifting time.

[0162] Optionally, the touch feature data is the writing force, and the recognition module 15 is specifically used to determine the writing force based on the static force signal.

[0163] Optionally, the touch feature data is the writing material, and the recognition module 15 is specifically used to acquire the first signal feature of the elastic wave signal;

[0164] The writing material of the object being touched is determined based on the characteristics of the first signal.

[0165] Optionally, the touch feature data is the writing material, and the recognition module 15 is specifically used to generate a target pen-writing signal when a static force signal that meets the first signal range is detected after the infrared pen-writing signal.

[0166] Acquire the target elastic wave signal generated within a preset time after the target pen placement signal;

[0167] The writing material of the object being touched is determined based on the second signal characteristics of the target elastic wave signal.

[0168] Optionally, the infrared module 11 is specifically used to collect the occlusion signal generated when the touched object occludes the infrared light grid based on the infrared touch module, and use it as the infrared pen placement signal.

[0169] Optionally, the infrared module 11 is specifically used to collect the occlusion signal generated when the touched object occludes the infrared light grid based on the infrared touch module;

[0170] The touch signal generated when the object touches the screen is predicted based on the occlusion signal, and is used as the infrared pen placement signal.

[0171] Optionally, the signal separation module 14 is specifically used to separate the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency;

[0172] The static force signal is obtained by performing signal compensation processing on the static force signal.

[0173] Optionally, the signal separation module 14 is specifically used to input the sensor signal into the analog high-pass filter and the analog low-pass filter respectively, and separate them into the analog elastic wave signal and the analog quasi-static force signal; the analog high-pass filter and the analog low-pass filter are set based on the cutoff frequency;

[0174] The analog elastic wave signal and the analog quasi-static force signal are amplified using amplifier circuits to obtain the amplified analog elastic wave signal and the amplified analog static force signal.

[0175] The amplified analog elastic wave signal and the amplified analog quasi-static force signal are converted into elastic wave signal and quasi-static force signal respectively using an analog-to-digital converter.

[0176] Optionally, the signal separation module 14 is specifically used to convert the sensor signal into a digital signal via an analog-to-digital converter;

[0177] The digital signal is input into a high-pass digital filter and a low-pass digital filter respectively to separate the elastic wave signal and the quasi-static force signal; the high-pass filter and the low-pass filter are set based on the cutoff frequency.

[0178] Optionally, the reset module 12 is also used to collect the infrared pen lift signal generated when the touched object leaves the screen based on the infrared touch module;

[0179] Determine the second moment after the generation of the infrared pen lifting signal, and then perform signal reset processing on the piezoelectric sensor at the second moment.

[0180] It should be noted that the touch detection device for interactive tablets provided in the above embodiments is only illustrated by the division of the above functional modules when executing the touch detection method for interactive tablets. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the touch detection device for interactive tablets and the touch detection method embodiments for interactive tablets provided in the above embodiments belong to the same concept, and the implementation process is detailed in the method embodiments, which will not be repeated here.

[0181] The sequence numbers of the embodiments described above are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0182] This application embodiment also provides a computer storage medium storing a computer program, which, when executed by a processor, implements the above-described functionality. Figures 5-14 The touch detection method for interactive flat panels shown in the embodiment can be found in the following description for its specific execution process: Figures 5-14 The specific details of the illustrated embodiments will not be elaborated here.

[0183] Please refer to Figure 16This diagram illustrates the structure of an electronic device provided in an exemplary embodiment of this specification. The electronic device in this specification may include one or more components such as a processor 110, a memory 120, an input device 130, an output device 140, and a bus 150. The processor 110, memory 120, input device 130, and output device 140 may be connected via the bus 150.

[0184] Processor 110 may include one or more processing cores. Processor 110 connects to various parts of the electronic device using various interfaces and lines, and executes various functions of terminal 100 and processes data by running or executing instructions, programs, code sets, or instruction sets stored in memory 120, and by calling data stored in memory 120. Optionally, processor 110 may be implemented using at least one hardware form of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). Processor 110 may integrate one or more of the following: Central Processing Unit (CPU), Graphics Processing Unit (GPU), and modem. The CPU primarily handles the operating system, user page, and applications; the GPU is responsible for rendering and drawing the displayed content; and the modem handles wireless communication. It is understood that the modem may also not be integrated into processor 110 and may be implemented separately using a communication chip.

[0185] The memory 120 may include random access memory (RAM) or read-only memory (ROM). Optionally, the memory 120 may include non-transitory computer-readable storage medium. The memory 120 may be used to store instructions, programs, code, code sets, or instruction sets. The memory 120 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for implementing at least one function (such as touch function, sound playback function, image playback function, etc.), instructions for implementing the various method embodiments described above, etc. The operating system may be the Android system, including systems deeply developed based on the Android system, the iOS system developed by Apple Inc., including systems deeply developed based on the iOS system, or other systems.

[0186] The memory 120 can be divided into operating system space and user space. The operating system runs in the operating system space, while native and third-party applications run in user space. To ensure that different third-party applications can achieve good running performance, the operating system allocates corresponding system resources for each application. However, different application scenarios within the same third-party application have different requirements for system resources. For example, in local resource loading scenarios, third-party applications have high requirements for disk read speed; in animation rendering scenarios, third-party applications have high requirements for GPU performance. Since the operating system and third-party applications are independent of each other, the operating system often cannot promptly perceive the current application scenario of a third-party application, resulting in the operating system's inability to adapt system resources accordingly.

[0187] In order for the operating system to distinguish the specific application scenarios of third-party applications, it is necessary to establish data communication between the third-party applications and the operating system. This would allow the operating system to obtain the current scenario information of the third-party applications at any time, and then perform targeted system resource adaptation based on the current scenario.

[0188] The input device 130 is used to receive input instructions or data, and includes, but is not limited to, a keyboard, mouse, camera, microphone, or touch device. The output device 140 is used to output instructions or data, and includes, but is not limited to, a display device and a speaker. In one example, the input device 130 and the output device 140 can be combined, and the input device 130 and the output device 140 can be a touch display screen.

[0189] The touch display screen can be designed as a full-screen, curved screen, or irregularly shaped screen. It can also be designed as a combination of a full-screen and a curved screen, or a combination of an irregularly shaped screen and a curved screen; however, this application does not limit the specific design of the touch display screen.

[0190] In addition, those skilled in the art will understand that the structure of the electronic device shown in the above figures does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown, or combine certain components, or have different component arrangements. For example, the electronic device may also include radio frequency circuits, input units, sensors, audio circuits, WiFi modules, power supplies, Bluetooth modules, etc., which will not be described in detail here.

[0191] exist Figure 13 In the illustrated electronic device, the processor 110 can be used to call computer applications stored in the memory 120 and specifically perform the following operations:

[0192] Based on the infrared touch module, the infrared pen signal generated when a touch object touches the screen is collected;

[0193] Determine the first moment before the generation of the infrared pen-drop signal, and perform signal reset processing on the piezoelectric sensor at the first moment;

[0194] Acquire the sensor signal collected by the piezoelectric sensor after signal reset processing;

[0195] Elastic wave signals and static force signals are determined based on sensor signals;

[0196] Touch feature data of the object being touched are determined based on elastic wave signals and / or static force signals.

[0197] In one embodiment, the touch feature data is the writing start time and writing lift time. When the processor 110 executes the touch feature data of the touched object based on the static force signal, it specifically performs the following operations:

[0198] When a static force signal that meets the first signal range is detected after the infrared pen-fall signal, a target pen-fall signal is generated, and the generation time of the target pen-fall signal is determined as the writing pen-fall time.

[0199] When a static force signal that meets the second signal range is detected after the target pen-falling signal, a target pen-lifting signal is generated, and the generation time of the target pen-lifting signal is determined as the writing pen-lifting time.

[0200] In one embodiment, the touch feature data is the writing force. When the processor 110 executes the operation of determining the touch feature data of the touched object based on the static force signal, it specifically performs the following operations:

[0201] The writing force is determined based on static force signals.

[0202] In one embodiment, the touch feature data is a writing material, and when the processor 110 executes the operation of determining the touch feature data based on the elastic wave signal, it specifically performs the following operations:

[0203] Obtain the first signal characteristics of the elastic wave signal;

[0204] The writing material of the object being touched is determined based on the characteristics of the first signal.

[0205] In one embodiment, the touch feature data is the writing material. When the processor 110 executes the operation of determining the touch feature data of the touch object based on elastic wave signals and static force signals, it specifically performs the following operations:

[0206] When a static force signal that meets the first signal range is detected after the infrared pen-drop signal, a target pen-drop signal is generated.

[0207] Acquire the target elastic wave signal generated within a preset time after the target pen placement signal;

[0208] The writing material of the touch object is determined based on the second signal characteristics of the target elastic wave signal. In one embodiment, when the processor 110 executes the infrared pen-writing signal generated when the touch object touches the screen, which is collected by the infrared touch module, the following operations are performed:

[0209] The infrared touch module collects the occlusion signal generated when the touched object occludes the infrared light grid, and uses it as the infrared pen placement signal.

[0210] In one embodiment, when the processor 110 executes the infrared pen-drop signal generated when a touch object touches the screen, which is collected based on the infrared touch module, it specifically performs the following operations:

[0211] Based on the infrared touch module, the occlusion signal generated when the touched object occludes the infrared light grid is collected;

[0212] The touch signal generated when the object touches the screen is predicted based on the occlusion signal, and is used as the infrared pen placement signal.

[0213] In one embodiment, when the processor 110 performs the operation of determining the elastic wave signal and the static force signal based on the sensor signal, it specifically performs the following operations:

[0214] Based on the cutoff frequency, elastic wave signals and quasi-static force signals are separated from the sensor signals;

[0215] The static force signal is obtained by performing signal compensation processing on the static force signal.

[0216] In one embodiment, when the processor 110 performs the operation of separating the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency, it specifically performs the following operations:

[0217] The sensor signal is input into an analog high-pass filter and an analog low-pass filter respectively to separate the analog elastic wave signal and the analog static force signal; the analog high-pass filter and the analog low-pass filter are set based on the cutoff frequency.

[0218] The analog elastic wave signal and the analog quasi-static force signal are amplified using amplifier circuits to obtain the amplified analog elastic wave signal and the amplified analog static force signal.

[0219] The amplified analog elastic wave signal and the amplified analog quasi-static force signal are converted into elastic wave signal and quasi-static force signal respectively using an analog-to-digital converter.

[0220] In one embodiment, when the processor 110 performs the operation of separating the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency, it specifically performs the following operations:

[0221] The sensor signal is converted into a digital signal using an analog-to-digital converter;

[0222] The digital signal is input into a high-pass digital filter and a low-pass digital filter respectively to separate the elastic wave signal and the quasi-static force signal; the high-pass filter and the low-pass filter are set based on the cutoff frequency.

[0223] In one embodiment, the processor 110 also performs the following operations:

[0224] Based on the infrared touch module to collect the infrared pen lifting signal generated when the touched object leaves the screen;

[0225] Determine the second moment after the generation of the infrared pen lifting signal, and then perform signal reset processing on the piezoelectric sensor at the second moment.

[0226] In this embodiment, the infrared pen-drop signal generated when the touch object touches the screen is collected by the infrared touch module, and the piezoelectric sensor at the first moment before the generation of the infrared pen-drop signal is reset. This can solve the baseline drift problem of the piezoelectric sensor when it is used for a long time, improve the measurement accuracy of the piezoelectric sensor, and thus improve the accuracy of the touch feature data of the touch object determined based on the static force signal and / or elastic force signal measured by the piezoelectric sensor.

[0227] Furthermore, the infrared touch module collects the occlusion signal generated when the touched object blocks the infrared light grid, which is used as the infrared pen-drop signal. Alternatively, the touch signal can be further predicted based on the occlusion signal and identified as the infrared pen-drop signal. At the first moment before the generation of the infrared pen-drop signal, the piezoelectric sensor is reset. The sensor signal collected by the piezoelectric sensor after the signal reset is obtained. The sensor signal is converted into a voltage signal via a charge amplification circuit. Since the elastic wave signal and the quasi-static force signal have significant differences in frequency distribution, the sensor output signal can be separated using an analog filter or a digital filter based on the cutoff frequency to obtain the elastic wave signal and the static force signal. The touch feature data of the touched object is determined based on the elastic wave signal and / or the static force signal. The infrared pen-lift signal generated when the touched object leaves the screen is collected by the infrared touch module. At the second moment after the generation of the infrared pen-lift signal, the piezoelectric sensor is reset to avoid error accumulation that could cause the sensor signal to exceed its range, thus ensuring the measurement effect of the piezoelectric sensor.

[0228] Furthermore, by analyzing static force signals, touch feature data such as writing placement time, writing lifting time, and writing force can be accurately obtained. By analyzing the signal characteristics of the elastic wave signal after the writing placement signal, the writing material can be determined. The accuracy of determining the writing material can be further improved by using static force signals and elastic wave signals, thus realizing the determination of rich touch feature data and improving the accuracy of touch feature data.

[0229] Additionally, this application provides a computer program product that includes a computer program. When the computer program is executed by a processor of an electronic device, it enables the processor to at least perform the functions described above. Figures 5 to 14 The embodiment shown provides a touch detection method for interactive flat panels.

[0230] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The aforementioned program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The aforementioned storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0231] The above-disclosed embodiments are merely preferred embodiments of this specification and should not be construed as limiting the scope of this specification. Therefore, any equivalent variations made in accordance with the claims of this specification shall still fall within the scope of this specification.

Claims

1. A touch detection method for interactive flat panels, characterized in that, The interactive flat panel includes a touch detection system, which includes a piezoelectric sensor and an infrared touch module. The method includes: The infrared touch module collects infrared pen signals generated when a touch object touches the screen. Determine a first moment before the generation time of the infrared pen-drop signal, and perform signal reset processing on the piezoelectric sensor at the first moment; Acquire the sensor signal collected by the piezoelectric sensor after the signal reset processing; The elastic wave signal and static force signal are determined based on the sensor signals; The touch feature data of the touch object are determined based on the elastic wave signal and / or the static force signal.

2. The method as described in claim 1, characterized in that, The touch feature data includes the time of pen placement and the time of pen lifting. The step of determining the touch feature data of the touched object based on the static force signal includes: When the static force signal is detected to meet the first signal range after the infrared pen-falling signal, a target pen-falling signal is generated, and the generation time of the target pen-falling signal is determined as the writing pen-falling time. When the static force signal is detected to meet the second signal range after the target pen-drop signal, a target pen-lifting signal is generated, and the generation time of the target pen-lifting signal is determined as the writing pen-lifting time.

3. The method as described in claim 1, characterized in that, The touch feature data is the writing pressure; The step of determining the touch feature data of the touched object based on the static force signal includes: The writing force is determined based on the static force signal.

4. The method as described in claim 1, characterized in that, The touch feature data is the writing material; The step of determining the touch feature data of the touched object based on the elastic wave signal includes: Obtain the first signal characteristics of the elastic wave signal; The writing material of the object being touched is determined based on the first signal feature.

5. The method as described in claim 1, characterized in that, The touch feature data is the writing material; The step of determining the touch feature data of the touched object based on the elastic wave signal and the static force signal includes: When the static force signal is detected to meet the first signal range after the infrared pen-drop signal, a target pen-drop signal is generated; Acquire the target elastic wave signal generated within a preset time after the target pen placement signal; The writing material of the touch object is determined based on the second signal characteristics of the target elastic wave signal.

6. The method as described in claim 1, characterized in that, The infrared pen-drop signal generated when a touch object touches the screen, collected by the infrared touch module, includes: The infrared touch module collects the occlusion signal generated when the touched object occludes the infrared light grid, which is then used as the infrared pen placement signal.

7. The method as described in claim 1, characterized in that, The infrared pen-drop signal generated when a touch object touches the screen, collected by the infrared touch module, includes: The infrared touch module collects the occlusion signal generated when the touched object blocks the infrared light grid. The touch signal generated when the object touches the screen is predicted based on the occlusion signal, and is used as the infrared pen placement signal.

8. The method as described in claim 1, characterized in that, The determination of the elastic wave signal and static force signal based on the sensor signal includes: Based on the cutoff frequency, elastic wave signals and quasi-static force signals are separated from the sensor signals; The quasi-static force signal is subjected to signal compensation processing to obtain a static force signal.

9. The method as described in claim 8, characterized in that, The separation of the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency includes: The sensor signals are input into an analog high-pass filter and an analog low-pass filter respectively to separate the analog elastic wave signal and the analog quasi-static force signal; the analog high-pass filter and the analog low-pass filter are set based on the cutoff frequency; The simulated elastic wave signal and the simulated quasi-static force signal are amplified using amplifier circuits to obtain amplified simulated elastic wave signal and amplified simulated static force signal, respectively. The amplified analog elastic wave signal and the amplified analog static force signal are converted into elastic wave signal and quasi-static force signal by an analog-to-digital converter.

10. The method as described in claim 8, characterized in that, The separation of the elastic wave signal and the quasi-static force signal from the sensor signal based on the cutoff frequency includes: The sensor signal is converted into a digital signal using an analog-to-digital converter; The digital signals are input into a high-pass digital filter and a low-pass digital filter respectively to separate the elastic wave signal and the quasi-static force signal; the high-pass filter and the low-pass filter are set based on the cutoff frequency.

11. The method as described in claim 1, characterized in that, The method further includes: The infrared touch module collects the infrared pen lifting signal generated when the touched object leaves the screen. Determine a second time after the generation time of the infrared pen-lifting signal, and perform signal reset processing on the piezoelectric sensor at the second time.

12. A touch detection device for an interactive flat panel, characterized in that, The device includes: An infrared module is used to collect infrared pen-drop signals generated when a touch object touches the screen, based on the infrared touch module. A reset module is used to determine a first moment before the generation time of the infrared pen-drop signal and to perform signal reset processing on the piezoelectric sensor at the first moment. The acquisition module is used to acquire the sensor signal collected by the piezoelectric sensor after the signal reset processing; The signal separation module is used to determine the elastic wave signal and the static force signal based on the sensor signal; The identification module is used to determine the touch feature data of the touch object based on the elastic wave signal and / or the static force signal.

13. An electronic device, characterized in that, include: Processor and memory; The memory stores a computer program adapted to be loaded by the processor and to execute the steps of the method as described in any one of claims 1 to 11.

14. A computer storage medium, characterized in that, The computer storage medium stores a computer program that, when executed by a processor, implements the steps of the method as described in any one of claims 1 to 11.

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