Electromagnetic induction detection circuit, driving method thereof, device, handwriting device and medium

Abstract

The application relates to the technical field of electromagnetic handwriting, and particularly provides an electromagnetic induction detection circuit, a driving method thereof, equipment, a handwriting device and a medium, and aims to solve the problem of how to simply and reliably realize electromagnetic induction detection between an electromagnetic pen and an electromagnetic handwriting screen. To this end, the electromagnetic induction detection circuit comprises an excitation driving circuit and an induction detection circuit; the excitation driving circuit transmits an excitation signal to an electromagnetic induction coil on the electromagnetic handwriting screen in a driving excitation stage of a detection period, and stops transmitting the excitation signal in a signal detection stage; a passive electromagnetic pen converts a first electromagnetic signal transmitted by the electromagnetic induction coil into electric energy, and in response to stopping receiving the first electromagnetic signal, sends a second electromagnetic signal to the electromagnetic induction coil according to the electric energy; and the induction detection circuit detects an induced current generated by the electromagnetic induction coil in the signal detection stage. Based on the above circuit, electromagnetic induction detection between the electromagnetic pen and the electromagnetic handwriting screen can be realized quickly and accurately.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic handwriting technology, specifically providing an electromagnetic induction detection circuit and its driving method, device, handwriting apparatus, and medium. Background Technology

[0002] An electromagnetic handwriting device can include an electromagnetic pen and an electromagnetic writing screen. The electromagnetic writing screen integrates an antenna board, and the electromagnetic pen can be an active or passive electromagnetic pen. When a passive electromagnetic pen is moved on the electromagnetic writing screen, the transmitting coil of the antenna board sends an excitation signal. The electromagnetic pen receives this excitation signal, and simultaneously, the resonant circuit within the electromagnetic pen resonates under the excitation signal, allowing the pen to store electromagnetic energy. When the transmitting coil stops sending the excitation signal, the resonant circuit within the electromagnetic pen continues to resonate using the stored electromagnetic energy, enabling the pen to transmit electromagnetic signals. The receiving coil of the antenna board receives these electromagnetic signals. The closer the receiving coil is to the position of the electromagnetic pen on the antenna board, the stronger the electromagnetic signal it receives. Based on this, the position of the electromagnetic pen on the antenna board can be determined according to the magnitude of the electromagnetic signals received by each receiving coil on the antenna board. Furthermore, the transmitting and receiving coils on the antenna board can be independent coils or a time-division multiplexed single coil.

[0003] Currently, there is a need to provide a simple and reliable solution to achieve electromagnetic induction detection between the electromagnetic pen and the electromagnetic handwriting screen, so as to accurately determine the position of the electromagnetic pen on the electromagnetic handwriting screen. Summary of the Invention

[0004] This application aims to solve the above-mentioned technical problems, namely, to solve or at least partially solve the following technical problems: how to simply and reliably realize electromagnetic induction detection between an electromagnetic pen and an electromagnetic handwriting screen, so as to accurately obtain the position of the electromagnetic pen on the electromagnetic handwriting screen.

[0005] In a first aspect, this application provides an electromagnetic induction detection circuit for an electromagnetic handwriting device, the electromagnetic handwriting device including a passive electromagnetic pen and an electromagnetic handwriting screen, and the electromagnetic induction detection circuit including an excitation drive circuit and an induction detection circuit.

[0006] The excitation driving circuit is used to: in response to the first driving signal, transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle, stop transmitting the excitation signal during the signal detection phase of the detection cycle, and the electromagnetic induction coil sends out a first electromagnetic signal under the action of the excitation signal.

[0007] The passive electromagnetic pen is used to: in response to receiving the first electromagnetic signal, convert the first electromagnetic signal into electrical energy for storage; and in response to stopping receiving the first electromagnetic signal, send a second electromagnetic signal to the electromagnetic induction coil according to the stored electrical energy, wherein the electromagnetic induction coil generates an induced current under the action of the second electromagnetic signal.

[0008] The induction detection circuit is used to: detect the induced current generated by the electromagnetic induction coil in response to the second driving signal during the signal detection phase.

[0009] In one technical solution of the above-mentioned electromagnetic induction detection circuit, the electromagnetic induction detection circuit is disposed on the electromagnetic handwriting screen, and multiple leads are evenly arranged in the horizontal and vertical directions of the electromagnetic handwriting screen. The electromagnetic induction coil is a ring coil formed by two leads on the electromagnetic handwriting screen that are electrically connected to the electromagnetic induction detection circuit. The two leads are two leads in the horizontal or vertical direction of the electromagnetic handwriting screen.

[0010] In one technical solution of the above electromagnetic induction detection circuit, the excitation drive circuit includes a signal generation circuit, an excitation capacitor, a first excitation switch and a second excitation switch. The first excitation switch is connected to the first end of the electromagnetic induction coil, and the second excitation switch is connected to the second end of the electromagnetic induction coil.

[0011] The signal generation circuit is used to generate a first excitation signal and a second excitation signal, wherein the first excitation signal and the second excitation signal have the same frequency and a phase difference of 180°;

[0012] The first terminal of the signal generation circuit is connected to the first excitation switch through the excitation capacitor, and the second terminal of the signal generation circuit is connected to the second excitation switch. The first terminal is used to output the first excitation signal, and the second terminal is used to output the second excitation signal.

[0013] In one technical solution of the above electromagnetic induction detection circuit, the signal generation circuit includes an excitation signal source, a positive excitation signal amplifier, and a negative excitation signal amplifier;

[0014] The excitation signal source is used to: output an excitation signal;

[0015] The output terminal of the excitation signal source is connected to the positive input terminal of the positive excitation signal amplifier, which is used to amplify the excitation signal in phase to form the first excitation signal.

[0016] The output terminal of the excitation signal source is also connected to the negative input terminal of the negative excitation signal amplifier, which is used to invert and amplify the excitation signal to form the second excitation signal.

[0017] The first and second terminals of the signal generation circuit are the output terminals of the positive excitation signal amplifier and the negative excitation signal amplifier, respectively.

[0018] In one technical solution of the above electromagnetic induction detection circuit, the excitation capacitor and the electromagnetic induction coil form a first resonant circuit, and the inductive inductor in the passive electromagnetic pen and the storage capacitor form a second resonant circuit. The resonant frequency of the first resonant circuit and the resonant frequency of the second resonant circuit are the same as the frequency of the first excitation signal.

[0019] In one technical solution of the above electromagnetic induction detection circuit, the induction detection circuit includes a first detection switch, a second detection switch, a coupling capacitor and a signal detection circuit, wherein the first detection switch is connected to a first end of the electromagnetic induction coil and the second detection switch is connected to a second end of the electromagnetic induction coil.

[0020] The first terminal of the signal detection circuit is connected to the first detection switch through the coupling capacitor, and the second terminal of the signal detection circuit is connected to the second detection switch;

[0021] The signal detection circuit includes a detection resistor, which is used to detect and output the voltage signal generated by the induced current across the detection resistor.

[0022] In one technical solution of the above electromagnetic induction detection circuit, the signal detection circuit further includes a current amplifier and a feedback capacitor, wherein the first terminal and the second terminal of the signal detection circuit are respectively the negative input terminal and the positive input terminal of the current amplifier;

[0023] The two ends of the detection resistor are connected to the negative input terminal and the output terminal of the current amplifier, respectively, and the feedback capacitor is connected in parallel with the detection resistor.

[0024] In one technical solution of the above electromagnetic induction detection circuit, the induction detection circuit further includes a filter circuit and a bandpass amplifier circuit;

[0025] The filtering circuit is used to: filter the voltage signal output by the signal detection circuit to obtain a filtered voltage signal;

[0026] The bandpass amplifier circuit is used to amplify a filtered voltage signal whose frequency is within a preset bandpass frequency range to obtain an amplified voltage signal. In other words, the bandpass amplifier circuit can amplify the signal response within a certain frequency band (such as the preset bandpass frequency range mentioned above) while suppressing signals of other higher or lower frequencies, thus achieving specific frequency signal amplification and noise suppression. The specific frequency signal is a bandpass signal, and the center frequency of this bandpass signal is the same as the frequency of the excitation signal, the resonant frequency of the first resonant circuit (i.e., the resonant circuit formed by the excitation capacitor and the electromagnetic induction coil), and the resonant frequency of the second resonant circuit (i.e., the resonant circuit formed by the inductor and the storage capacitor in the passive electromagnetic pen).

[0027] In one technical solution of the above electromagnetic induction detection circuit, the inductive inductor and storage capacitor in the passive electromagnetic pen form a second resonant circuit, and the center frequency of the preset passband range, the resonant frequency of the second resonant circuit, and the frequency of the excitation signal are the same.

[0028] In one technical solution of the above electromagnetic induction detection circuit, the bandpass amplifier circuit includes a bandpass amplifier, a first resistor, a second resistor, a first capacitor, and a second capacitor. The first end of the first resistor is connected to the filter circuit, the second end of the first resistor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the negative input terminal of the bandpass amplifier, and the positive input terminal of the bandpass amplifier is grounded.

[0029] The two ends of the second resistor are connected to the negative input and output of the bandpass amplifier, respectively. The first end of the second capacitor is connected between the first resistor and the first capacitor, and the second end of the second capacitor is connected to the output of the bandpass amplifier.

[0030] In one technical solution of the above electromagnetic induction detection circuit, the minimum cutoff frequency and the maximum cutoff frequency of the preset passband range are respectively and ; frequency at ~ The signal between them is amplified, while the frequency is less than And greater than The signal is suppressed, and the ideal amplification factor is 0.

[0031] , , and These represent the resistance values ​​of the first resistor and the second resistor, respectively. and These represent the capacitance values ​​of the first capacitor and the second capacitor, respectively.

[0032] In a second aspect, this application provides a driving method for an electromagnetic induction detection circuit, characterized in that the electromagnetic induction detection circuit is the electromagnetic induction detection circuit for an electromagnetic handwriting device as described in any one of the first aspects, and the method includes:

[0033] The electromagnetic induction detection circuit is periodically output with a circuit drive signal.

[0034] The circuit driving signal includes a first driving signal and a second driving signal.

[0035] The first driving signal includes a first level signal and a second level signal. The first level signal is used to control the excitation driving circuit in the electromagnetic induction detection circuit to transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle. The second level signal is used to control the excitation driving circuit to stop transmitting the excitation signal during the signal detection phase of the detection cycle. The level value of the first level signal is greater than the level value of the second level signal.

[0036] The second driving signal includes a third level signal and a fourth level signal. The third level signal is used to control the induction detection circuit in the electromagnetic induction detection circuit to stop detecting the induced current generated by the electromagnetic induction coil during the driving excitation phase. The fourth level signal is used to control the induction detection circuit to detect the induced current generated by the electromagnetic induction coil during the signal detection phase. The level value of the third level signal is lower than the level value of the fourth level signal.

[0037] In a third aspect, an electronic device is provided, comprising at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program that, when executed by the at least one processor, implements the method described in any of the technical solutions provided in the second aspect above.

[0038] In a fourth aspect, an electromagnetic handwriting device is provided, which includes a passive electromagnetic pen and an electromagnetic handwriting screen. The electromagnetic handwriting device also includes the electromagnetic induction detection circuit for the electromagnetic handwriting device described in any of the technical solutions provided in the first aspect above, as well as the electronic device provided in the third aspect above.

[0039] In a fifth aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored therein, the program codes being adapted to be loaded and run by a processor to perform the method described in any of the technical solutions provided in the second aspect above.

[0040] The above-described technical solutions of this application have at least one or more of the following beneficial effects:

[0041] In one technical solution of the electromagnetic induction detection circuit for an electromagnetic handwriting device provided in this application, the electromagnetic handwriting device may include a passive electromagnetic pen and an electromagnetic handwriting screen, and the electromagnetic induction detection circuit may include an excitation driving circuit and an induction detection circuit; the excitation driving circuit is used to respond to a first driving signal, transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle, and stop transmitting the excitation signal during the signal detection phase of the detection cycle, and the electromagnetic induction coil sends out a first electromagnetic signal under the action of the excitation signal;

[0042] The passive electromagnetic pen is used to convert the first electromagnetic signal into electrical energy for storage in response to receiving the first electromagnetic signal; and to send a second electromagnetic signal to the electromagnetic induction coil based on the stored electrical energy in response to stopping receiving the first electromagnetic signal, so that the electromagnetic induction coil generates an induced current under the action of the second electromagnetic signal; the induction detection circuit is used to detect the induced current generated by the electromagnetic induction coil during the signal detection stage in response to a second driving signal.

[0043] Based on the above implementation scheme, when performing electromagnetic induction detection on the passive electromagnetic pen and the electromagnetic handwriting screen, the excitation drive circuit and the induction detection circuit can work in a time-sharing manner within a detection cycle, quickly and accurately detecting the induced current generated by the electromagnetic induction coil, thereby helping to accurately determine the position of the passive electromagnetic pen on the electromagnetic handwriting screen.

[0044] Furthermore, in the above implementation scheme, the electromagnetic induction coil can serve as a transmitting coil, sending a first electromagnetic signal during the driving excitation phase. It can also serve as a receiving coil, receiving a second electromagnetic signal during the signal detection phase. Therefore, the electromagnetic induction coil can be understood as a coil that time-division multiplexes signal transmission and reception. Multiple electromagnetic induction coils can be distributed on the electromagnetic handwriting screen. For any given electromagnetic induction coil, when writing on the screen with a passive electromagnetic pen, the closer the pen is to the coil, the stronger the energy of the first electromagnetic signal received from that coil. Consequently, the energy of the second electromagnetic signal sent to the coil is also stronger, resulting in a larger induced current. Therefore, the position of the passive electromagnetic pen on the electromagnetic handwriting screen can be determined by utilizing the magnitude of the induced current generated by each electromagnetic induction coil. Attached Figure Description

[0045] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Wherein:

[0046] Figure 1This is a waveform diagram of the resonant voltage generated when a resonant circuit according to an embodiment of this application resonates under electromagnetic signal excitation;

[0047] Figure 2 This is a waveform diagram of the resonant voltage when an electromagnetic pen, according to an embodiment of this application, sends out electromagnetic signals;

[0048] Figure 3 This is a schematic diagram of an electromagnetic induction detection circuit according to an embodiment of this application. Figure 1 ;

[0049] Figure 4 This is a schematic diagram of the lead arrangement on an electromagnetic handwriting screen according to an embodiment of this application;

[0050] Figure 5 This is an equivalent circuit diagram of an electromagnetic induction coil formed by horizontal leads on an electromagnetic handwriting screen according to an embodiment of this application;

[0051] Figure 6 This is an equivalent circuit diagram of an electromagnetic induction coil formed by longitudinal leads on an electromagnetic handwriting screen according to an embodiment of this application;

[0052] Figure 7 This is a schematic diagram of an electromagnetic induction detection circuit according to an embodiment of this application. Figure 2 ;

[0053] Figure 8 This is a schematic diagram of the waveform of the circuit drive signal according to an embodiment of this application;

[0054] Figure 9 This is a schematic diagram of the main structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0055] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0056] First, an embodiment of the electromagnetic induction detection circuit for an electromagnetic handwriting device provided in this application will be described. The electromagnetic handwriting device may include a passive electromagnetic pen and an electromagnetic handwriting screen.

[0057] The passive electromagnetic pen contains a resonant circuit. When the user moves the pen on the electromagnetic handwriting screen, it receives electromagnetic signals emitted by the electromagnetic induction coil (or antenna coil) on the screen. Excited by these signals, the resonant circuit resonates, generating a resonant voltage and current. Based on these resonant voltage and current, the energy of the electromagnetic signal is converted into electrical energy and stored. When the electromagnetic induction coil on the screen stops emitting signals, the resonant circuit within the pen continues to resonate using the stored energy, transmitting electromagnetic signals. As the stored energy decreases, the resonant voltage and current gradually decrease. Once the stored energy has been completely converted into electromagnetic signals and transmitted, the resonant voltage and current drop to zero. For example, Figure 1 The waveform of the resonant voltage generated when the resonant circuit resonates under electromagnetic signal excitation is shown as an example. Figure 2 An exemplary diagram shows the waveform of the resonant voltage when the electromagnetic pen sends out electromagnetic signals. Figure 1 and Figure 2 The horizontal axis represents time, and the vertical axis represents the resonant voltage value. For example... Figure 1 As shown, after resonance begins, the resonant voltage gradually increases from zero until it reaches its maximum. Tr represents the time required for the resonant voltage to rise from zero to 90% of its maximum value. Figure 2 As shown, when an electromagnetic wave sends out an electromagnetic signal, the resonant voltage gradually decreases from its maximum value to zero. The resonant circuit is an LC resonant circuit composed of the resonant capacitor C and the coil inside the electromagnetic pen. R pen This indicates the internal resistance of the coil.

[0058] In the embodiments of this application, the electromagnetic induction detection circuit may include an excitation drive circuit and an induction detection circuit, which will be described below.

[0059] The excitation driving circuit can respond to the first driving signal, transmitting an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle, and stopping the transmission of the excitation signal during the signal detection phase of the detection cycle. The electromagnetic induction coil sends out a first electromagnetic signal under the action of the excitation signal. A detection cycle includes two phases in sequence: the driving excitation phase and the signal detection phase. The function of the first driving signal can be understood as the driving excitation circuit transmitting an excitation signal to the electromagnetic induction coil during the driving excitation phase.

[0060] When the passive electromagnetic pen moves on the electromagnetic handwriting screen, it can receive the first electromagnetic signal emitted by the electromagnetic induction coil and convert it into electrical energy for storage. During the signal detection phase, the electromagnetic induction coil stops emitting the first electromagnetic signal, and the passive electromagnetic pen no longer receives it (i.e., it stops receiving the first electromagnetic signal). In response to ceasing to receive the first electromagnetic signal, the passive electromagnetic pen can also send a second electromagnetic signal to the electromagnetic induction coil based on the stored electrical energy. The electromagnetic induction coil then generates an induced current under the influence of the second electromagnetic signal.

[0061] The induction detection circuit can respond to the second driving signal and detect the induced current generated by the electromagnetic induction coil during the signal detection phase. The function of the second driving signal can be understood as driving the induction detection circuit to detect the induced current generated by the electromagnetic induction coil during the signal detection phase.

[0062] The following is in conjunction with the appendix Figure 3 The electromagnetic induction detection circuit of the embodiment of this application will be described. For example... Figure 3 As shown, the excitation drive circuit is connected to both ends of the electromagnetic induction coil. The excitation drive circuit can transmit an excitation signal to the electromagnetic induction coil. Under the excitation of this excitation signal, the electromagnetic induction coil sends out a first electromagnetic signal. The passive electromagnetic pen can receive this first electromagnetic signal and convert it into electrical energy for storage. The induction detection circuit is also connected to both ends of the electromagnetic induction coil. The induction detection circuit can detect the induced current generated by the electromagnetic induction coil.

[0063] In addition, such as Figure 3 As shown, the electromagnetic induction coil is a closed induction coil formed by two leads (i.e., lead ETn and lead ETn+1). The first end of the excitation drive circuit is connected to the first end of lead ETn, the second end of the excitation drive circuit is connected to the first end of lead ETn+1, and the second end of lead ETn is connected to the second end of lead ETn+1. R ETn and L ETn R represents the resistance and inductance of lead ETn, respectively. ETn+1 and L ETn+1 These represent the resistance and inductance of lead ETn+1, respectively. Similarly, the first terminal of the induction detection circuit is connected to the first terminal of lead ETn, the second terminal of the induction detection circuit is connected to the first terminal of lead ETn+1, and the second terminal of lead ETn is connected to the second terminal of lead ETn+1.

[0064] The passive electromagnetic pen has an internal capacitor C. pen and coil L pen The coil L penUnder the first driving signal, the induction antenna inside the electromagnetic handwriting screen sends electromagnetic waves to induce current, and stores the induced current in the form of energy in coil L. pen and capacitor C pen Internally; under the second drive signal, the passive electromagnetic pen stores data in coil L. pen and capacitor C pen The energy within the coil sends a second electromagnetic signal to the electromagnetic induction coil in the form of a resonant wave, L pen and R pen These represent the inductance and resistance of the coil, respectively, and the capacitance C. pen This coil and the resonant circuit can be formed.

[0065] Based on the above electromagnetic induction detection circuit, when performing electromagnetic induction detection on a passive electromagnetic pen and an electromagnetic handwriting screen, the excitation drive circuit and the induction detection circuit can work in a time-sharing manner within a detection cycle, quickly and accurately detecting the induced current generated by the electromagnetic induction coil, thereby helping to accurately determine the position of the passive electromagnetic pen on the electromagnetic handwriting screen.

[0066] Furthermore, in the above embodiments, the electromagnetic induction coil can serve as a transmitting coil, sending a first electromagnetic signal during the driving excitation phase. It can also serve as a receiving coil, receiving a second electromagnetic signal during the signal detection phase. Therefore, the electromagnetic induction coil can be understood as a coil that time-division multiplexes signal transmission and reception. Multiple electromagnetic induction coils can be distributed on the electromagnetic handwriting screen. For any given electromagnetic induction coil, when writing on the screen with a passive electromagnetic pen, the closer the pen is to the coil, the stronger the energy of the first electromagnetic signal received from that coil. Consequently, the energy of the second electromagnetic signal sent to the coil is also stronger, resulting in a larger induced current generated by the coil. Therefore, the position of the passive electromagnetic pen on the electromagnetic handwriting screen can be determined by utilizing the magnitude of the induced current generated by each coil.

[0067] The following description continues with an embodiment of the electromagnetic induction detection circuit provided in this application, specifically describing the electromagnetic induction coil on the electromagnetic handwriting screen.

[0068] The electromagnetic handwriting screen has multiple leads evenly arranged horizontally and vertically. Each pair of leads horizontally forms an electromagnetic induction coil, and each pair of leads vertically also forms an electromagnetic induction coil. For example... Figure 4 As shown, the electromagnetic handwriting screen has N+1 leads evenly arranged horizontally, from lead ET0 to lead ETN. Any two leads can be connected through a common lead ETcom to form a coil. For example, leads ETn and ETn+1 can form a coil. Figure 5 An example is shown of the equivalent circuit of the coil, RETn L ETn and C ETn R represents the resistance, inductance, and load capacitance of the lead ETn, respectively. ETn+1 L ETn+1 and C ETn+1 These represent the resistance, inductance, and load capacitance of lead ETn+1, respectively. C ETcom This indicates the load capacitance of the common lead ETcom.

[0069] like Figure 4 As shown, the electromagnetic handwriting screen has M+1 leads evenly arranged vertically, from lead ER0 to lead ERM. Any two leads can be connected through a common lead ERcom to form a coil. For example, leads ERm and ERm+1 can form a coil. Figure 6 An example is shown of the equivalent circuit of the coil, R ERm L ERm and C ERm R represents the resistance, inductance, and load capacitance of the lead ERm, respectively. ERm+1 L ERm+1 and C ERm+1 These represent the resistance, inductance, and load capacitance of lead ERm+1, respectively. ERcom This indicates the load capacitance of the common lead ERcom.

[0070] In this embodiment, the electromagnetic induction detection circuit is disposed on the electromagnetic handwriting screen. When the two leads on the electromagnetic handwriting screen are electrically connected to the electromagnetic induction detection circuit, these two leads form a loop electromagnetic induction coil. The two leads refer to the two horizontal leads or the two vertical leads of the electromagnetic handwriting screen. Taking leads ETn and ETn+1 as an example, when the electromagnetic induction detection circuit is electrically connected to leads ETn and ETn+1, these two leads form a loop electromagnetic induction coil. The two ends of the excitation drive circuit are connected to leads ETn and ETn+1 respectively, and the two ends of the induction detection circuit are also connected to leads ETn and ETn+1 respectively.

[0071] The embodiments of the electromagnetic induction detection circuit provided in this application will be described below, specifically the excitation drive circuit.

[0072] In some embodiments of this application, the excitation drive circuit may include a signal generation circuit, an excitation capacitor, a first excitation switch, and a second excitation switch.

[0073] The signal generation circuit can generate the first excitation signal V. TX+ Second excitation signal V TX-The first and second excitation signals have the same frequency and a phase difference of 180°. This 180° phase difference indicates that the first and second excitation signals are in opposite directions; when the first excitation signal is positive, the second excitation signal is negative, and vice versa. That is, V... TX+ =-V TX- .

[0074] The first excitation switch is connected to the first end of the electromagnetic induction coil. The first end of the signal generation circuit is connected to the first excitation switch through an excitation capacitor. That is, the electromagnetic induction coil, the first excitation switch, the excitation capacitor, and the signal generation circuit are connected in sequence. The first excitation switch is used to turn on or off the electrical connection between the first end of the electromagnetic induction coil and the excitation capacitor. The excitation capacitor and the electromagnetic induction coil form a first resonant circuit. The inductive inductance and storage capacitor within the passive electromagnetic pen form a second resonant circuit. The resonant frequencies of the first and second resonant circuits are the same as the frequency of the first excitation signal.

[0075] The second excitation switch is connected to the second end of the electromagnetic induction coil, and the second end of the signal generation circuit is connected to the second excitation switch. That is, the electromagnetic induction coil, the second excitation switch, and the signal generation circuit are connected in sequence. The second excitation switch is used to turn on or off the electrical connection between the second end of the electromagnetic induction coil and the signal generation circuit.

[0076] The excitation capacitor and the electromagnetic induction coil can form a resonant circuit (i.e., the first resonant circuit mentioned above). Adjusting the capacitance value of the excitation capacitor can change the resonant frequency of this resonant circuit. When this resonant frequency is the same as the signal frequency of the excitation signal, the resonant current of the resonant circuit will reach its maximum, and the energy of the first electromagnetic signal emitted by the electromagnetic induction coil will also reach its maximum. Based on this, energy can be transferred (or charged) to the passive electromagnetic pen with maximum energy (or maximum resonant current). Those skilled in the art can predetermine the signal frequency of the excitation signal and then determine the capacitance value of the excitation capacitor based on the signal frequency. In practical applications, the signal frequency of the excitation signal is fixed; therefore, the capacitance value of the excitation capacitor is also fixed, and there is no need to repeatedly adjust the capacitance value of the excitation capacitor.

[0077] The excitation drive circuit can respond to the first drive signal and control the first and second excitation switches to close during the drive excitation phase of the detection cycle. The signal generation circuit can generate the first and second excitation signals, which are transmitted to the first and second terminals of the electromagnetic induction coil, respectively. The electromagnetic induction coil can send out the first electromagnetic signal according to the received excitation signal.

[0078] The excitation drive circuit will be described below.

[0079] In some embodiments according to this application, the signal generation circuit may include an excitation signal source, a positive excitation signal amplifier, and a negative excitation signal amplifier, wherein the positive and negative excitation signal amplifiers have the same amplification factor for the signal. The excitation signal source can be used to output an excitation signal, which may be a sine wave signal or a square wave signal.

[0080] The output of the excitation signal source is connected to the positive input of the positive excitation signal amplifier, and the negative input of the positive excitation signal amplifier is connected to analog ground. The positive excitation signal amplifier is used to amplify the excitation signal in phase to form the first excitation signal V. TX+ The output of the positive excitation signal amplifier serves as the first terminal of the signal generation circuit.

[0081] The output of the excitation signal source is also connected to the negative input of the negative excitation signal amplifier, and the positive input of the negative excitation signal amplifier is connected to analog ground. The negative excitation signal amplifier is used to invert and amplify the excitation signal to form the second excitation signal V. TX- The output of the negative excitation signal amplifier serves as the second terminal of the signal generation circuit.

[0082] In some implementations, the positive and negative excitation signal amplifiers can be operational amplifiers (OA).

[0083] The following is in conjunction with the appendix Figure 7 The excitation drive circuit of the embodiment of this application will be described.

[0084] like Figure 7 As shown, the excitation drive circuit may include a first excitation switch K. T1 Second excitation switch K T2 Excitation capacitor C Tx The signal generation circuit may include a positive excitation signal amplifier OP1, a negative excitation signal amplifier OP2, and an excitation signal source.

[0085] The output terminal of the excitation signal source is connected to the positive input terminal of the positive excitation signal amplifier OP1. The excitation signal output from the excitation signal source is amplified in phase by OP1 to obtain the first excitation signal V. TX+ The first excitation signal V TX+ sequentially through excitation capacitor C Tx First excitation switch K T1 The signal is input to the electromagnetic induction coil. The output of the excitation signal source is connected to the negative input of the negative excitation signal amplifier OP2. The excitation signal is then inverted and amplified by OP1 to obtain the second excitation signal V. TX- The second excitation signal V TX- via the second excitation switch K T2 Input is fed into the electromagnetic induction coil.

[0086] First driving signal T X Used to control the first excitation switch K T1 Second excitation switch K T2 Simultaneously closed or open, when K T1 K T2 Excitation signal V when closed TX+ V TX- Input to the electromagnetic induction coil, when K T1 K T2 Excitation signal V when disconnected TX+ V TX- No more input is given to the electromagnetic induction coil.

[0087] The embodiments of the electromagnetic induction detection circuit provided in this application will be described below, specifically the induction detection circuit.

[0088] In some embodiments of this application, the sensing circuit may include a first detection switch, a second detection switch, a coupling capacitor, and a signal detection circuit.

[0089] The first detection switch is connected to the first end of the electromagnetic induction coil, and the first end of the signal detection circuit is connected to the first detection switch through a coupling capacitor. That is, the electromagnetic induction coil, the first detection switch, the coupling capacitor, and the signal detection circuit are connected in sequence. The first detection switch is used to turn on or off the electrical connection between the first end of the electromagnetic induction coil and the coupling capacitor.

[0090] The second detection switch is connected to the second end of the electromagnetic induction coil, and the second end of the signal detection circuit is connected to the second detection switch. That is, the electromagnetic induction coil, the second detection switch, and the signal detection circuit are connected in sequence. The second detection switch is used to turn on or off the electrical connection between the second end of the electromagnetic induction coil and the signal detection circuit.

[0091] The signal detection circuit may include a detection resistor through which the induced current generated by the electromagnetic induction coil flows. The signal detection circuit can detect and output the voltage signal (or voltage drop) generated across the detection resistor by the induced current, using this voltage signal as the detection result of the electromagnetic induction detection circuit. The voltage signal can be represented as I×R. SMPL I and R SMPL These represent the induced current and the sensing resistance, respectively.

[0092] Adjusting the capacitance value of the coupling capacitor changes the impedance of the electromagnetic induction coil, which can be understood as the antenna impedance. When this impedance matches the detection resistor, the current generated by the electromagnetic induction coil can produce the maximum voltage drop across the detection resistor, thus detecting the maximum voltage signal. Those skilled in the art can predetermine the capacitance value of the coupling capacitor; in practical applications, the capacitance value of the coupling capacitor is fixed and does not require repeated adjustment.

[0093] The signal detection circuit can respond to the second drive signal and control the first and second detection switches to close in the detection cycle based on the signal detection result, so that the induced current generated by the electromagnetic induction coil can flow through the detection resistor and the voltage signal generated by the induced current on the detection resistor can be detected.

[0094] The signal detection circuit will be explained below.

[0095] In some embodiments according to this application, the signal detection circuit may include a current amplifier and a feedback capacitor in addition to a detection resistor. The first and second terminals of the signal detection circuit are the negative and positive input terminals of the current amplifier, respectively. The two ends of the detection resistor are connected to the negative input and output terminals of the current amplifier, respectively. The feedback capacitor is connected in parallel with the detection resistor. The induced current generated by the electromagnetic induction coil flows through the detection resistor, generating a voltage drop, which is output at the current amplifier's output terminal. In some embodiments, the current amplifier may be an operational amplifier.

[0096] Please refer to the appendix for further details. Figure 7 The following is in conjunction with the appendix Figure 7 The signal detection circuit is described below.

[0097] like Figure 7 As shown, the sensing detection circuit may include a first detection switch K. S1 Second detection switch K S2 Coupling capacitor C C and a signal detection circuit, which may include a detection resistor R SMPL Current amplifier OP3 and feedback capacitor C F V TIA The voltage signal output by OP3, V TIA =-I×R SMPL I represents the induced current. The first detection switch K... S1 Second detection switch K S2 Connect them to the two ends of the electromagnetic induction coil respectively.

[0098] The signal detection circuit will be explained below.

[0099] In some embodiments of this application, the signal detection circuit may further include a filtering circuit and a bandpass amplifier circuit. The filtering circuit filters the voltage signal output by the signal detection circuit to obtain a filtered voltage signal. The bandpass amplifier circuit amplifies the filtered voltage signal whose frequency is within a preset bandpass frequency range to obtain an amplified voltage signal. The center frequency of the preset bandpass frequency range, the resonant frequency of the second resonant circuit, and the frequency of the excitation signal are the same. This excitation signal is the excitation signal transmitted from the excitation drive circuit to the electromagnetic induction coil. The second resonant circuit is a resonant circuit formed by the inductor and storage capacitor within the passive electromagnetic pen. In some embodiments, the filtering circuit is a low-frequency filtering circuit; alternatively, the filtering circuit may be an RC filtering circuit.

[0100] In some implementations, the bandpass amplifier circuit may include a bandpass amplifier, a first resistor, a second resistor, a first capacitor, and a second capacitor.

[0101] The first terminal of the first resistor is connected to the filter circuit, the second terminal of the first resistor is connected to the first terminal of the first capacitor, the second terminal of the first capacitor is connected to the negative input terminal of the bandpass amplifier, and the positive input terminal of the bandpass amplifier is grounded. The two terminals of the second resistor are connected to the negative input terminal and the output terminal of the bandpass amplifier, respectively. The first terminal of the second capacitor is connected between the first resistor and the first capacitor, and the second terminal of the second capacitor is connected to the output terminal of the bandpass amplifier.

[0102] Please refer to the appendix for further details. Figure 7 The following is in conjunction with the appendix Figure 7 The signal detection circuit is described below.

[0103] like Figure 7 As shown, the filter circuit may include a resistor R LPF and capacitor C LPF resistance R LPF The first terminal is connected to the output terminal of the current amplifier OP3, and the resistor R LPF The second terminal is connected to the bandpass amplifier circuit, and capacitor C LPF The first end is connected to resistor R LPF Between the capacitor C and the bandpass amplifier circuit LPF The second end is connected to the simulated ground.

[0104] The bandpass amplifier circuit may include bandpass amplifier OP4 and a first resistor R. BPL Second resistor R BPH First capacitor C BPL Second capacitor C BPH First resistor R BPL The first terminal is connected to resistor R in the filter circuit. LPF The second end is connected to the first resistor R. BPL The second terminal is connected to the first capacitor CBPL The first terminal is connected to the first capacitor C. BPL The second terminal is connected to the negative input terminal of the bandpass amplifier OP4, and the positive input terminal of OP4 is connected to analog ground. The second resistor R BPH The two ends are connected to the negative input and output terminals of OP4, respectively, and the second capacitor C BPH The first end is connected to the first resistor R BPL With the first capacitor C BPL Between, the second capacitor C BPH The second terminal is connected to the output terminal of OP4, V OUT This is the voltage signal output by OP4.

[0105] Based on this circuit structure, the minimum cutoff frequency and maximum cutoff frequency of the preset passband range can be determined as follows: and .in, , Frequency at ~ The signal between them is amplified, while the frequency is less than And greater than The signal is suppressed consistently, and the ideal amplification factor is 0.

[0106] The following describes an embodiment of the driving method for the electromagnetic induction detection circuit provided in this application. This method can be applied to the electromagnetic induction detection circuit described in the aforementioned circuit embodiments.

[0107] In this embodiment, a circuit drive signal can be periodically output to the electromagnetic induction detection circuit. In each detection cycle, the electromagnetic induction detection circuit can detect the induced current generated by the electromagnetic induction coil on the electromagnetic handwriting screen under the control of the drive signal.

[0108] The circuit drive signal may include a first drive signal and a second drive signal.

[0109] The first driving signal may include a first level signal and a second level signal. The first level signal is used to control the excitation driving circuit in the electromagnetic induction detection circuit to transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle. The second level signal is used to control the excitation driving circuit to stop transmitting the excitation signal during the signal detection phase of the detection cycle. The level value of the first level signal is greater than the level value of the second level signal. The first level signal can be understood as a high level signal, and the second level signal can be understood as a low level signal.

[0110] The second driving signal may include a third-level signal and a fourth-level signal. The third-level signal is used to control the induction detection circuit in the electromagnetic induction detection circuit to stop detecting the induced current generated by the electromagnetic induction coil during the driving excitation phase. The fourth-level signal is used to control the induction detection circuit to detect the induced current generated by the electromagnetic induction coil during the signal detection phase. The level value of the third-level signal is lower than the level value of the fourth-level signal. The third-level signal can be understood as a low-level signal, and the fourth-level signal can be understood as a high-level signal.

[0111] The following is based on Figure 7 The driving method will be explained using the electromagnetic induction detection circuit shown as an example.

[0112] In this embodiment, the first drive signal is used to control the first excitation switch K. T1 Second excitation switch K T2 Simultaneously closing or opening. The first level signal in the first drive signal is specifically used to control switch K. T1 K T2 Simultaneously closed, thus the excitation signal V TX+ V TX- An input signal can be sent to an electromagnetic induction coil, which then sends out a first electromagnetic signal; the second level signal is specifically used to control K. T1 K T2 Disconnect simultaneously, so that the excitation signal V TX+ V TX- The input to the electromagnetic induction coil is no longer received, and the electromagnetic induction coil stops sending out the first electromagnetic signal.

[0113] The second drive signal is used to control the first detection switch K. S1 Second detection switch K S2 Simultaneously closing or opening. The third level signal in the second drive signal is specifically used to control switch K. S1 K S2 Simultaneously disconnected, the induction detection circuit will not detect the induced current generated by the electromagnetic induction coil; the fourth level signal is specifically used to control switch K. S1 K S2 When the circuit is closed simultaneously, the induced current generated by the electromagnetic induction coil can flow into the induction detection circuit, which can then detect this current.

[0114] like Figure 8 As shown, one detection cycle (i.e. Figure 8 The cycle (1 cycle) includes a drive excitation phase t1 and a signal detection phase t2, where TX and Sensing represent the first and second drive signals, respectively. During the drive excitation phase t1, the first and third level signals are high and low level signals, respectively. Under the control of these two signals, switch K... T1 KT2 Simultaneously close, switch K S1 K S2 Simultaneously disconnected, the excitation drive circuit transmits an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen. During the signal detection phase t2, the second and fourth level signals are low and high level signals, respectively. Under the control of these two signals, switch K... T1 K T2 Simultaneously disconnect, switch K S1 K S2 When closed simultaneously, the induction detection circuit can detect the induced current generated by the electromagnetic induction coil.

[0115] Specifically, in the driving excitation phase t1, the first excitation switch K T1 Second excitation switch K T2 Close, first detection switch K S1 Second detection switch K S2 When disconnected, the excitation signal is amplified in phase by the positive excitation signal amplifier OP1 to obtain the first excitation signal V. TX+ The excitation signal is amplified by the negative excitation signal amplifier OP2 through horizontal inversion to obtain the second excitation signal V. TX- Excitation signal V TX+ Passing sequentially through excitation capacitor C Tx First excitation switch K T1 Input to the first terminal ET of the electromagnetic induction coil n Excitation signal V TX- via the second excitation switch K T2 Input to the second terminal ET of the electromagnetic induction coil n+1 The electromagnetic induction coil sends out a first electromagnetic signal, which is received by the passive electromagnetic pen and converted into electrical energy for storage.

[0116] During signal detection phase t2, the first excitation switch K... T1 Second excitation switch K T2 Disconnect, first detection switch K S1 Second detection switch K S2 Close, the first terminal ET of the electromagnetic induction coil n Second end ET n+1 The electromagnetic induction coil is electrically connected to the inverting and non-inverting input terminals of the current amplifier OP3, respectively. The induced current generated by the electromagnetic induction coil is detected by the sensing resistor R. SMPL The voltage signal V is generated on the top TIA V TIA The output signal V is obtained by sequentially processing the signal through a filter circuit and a bandpass amplifier circuit. TOUT .

[0117] Those skilled in the art will understand that all or part of the processes in the method of the above-described embodiment can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0118] Another aspect of this application provides a computer-readable storage medium.

[0119] In one embodiment of a computer-readable storage medium according to this application, the computer-readable storage medium can be configured to store a program for driving a method of an electromagnetic induction detection circuit that performs the above-described method embodiments. This program can be loaded and run by a processor to implement the above-described method. For ease of explanation, only the parts related to the embodiments of this application are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of this application. The computer-readable storage medium can be a storage device comprising various electronic devices. Optionally, in the embodiments of this application, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0120] Another aspect of this application provides an electronic device.

[0121] In one embodiment of an electronic device according to this application, the electronic device may include at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program that, when executed by the at least one processor, implements the methods described in any of the above embodiments. See Appendix Figure 9 , Figure 9 The example illustrates a memory and processor connected via a bus communication connection.

[0122] In the description of this application, "processor" can include hardware, software, or a combination of both. A processor can be a central processing unit, microprocessor, graphics processor, digital signal processor, or any other suitable processor. A processor has data and / or signal processing capabilities. A processor can be implemented in software, in hardware, or a combination of both. Computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B.

[0123] Another aspect of this application provides an electromagnetic handwriting device.

[0124] In one embodiment of an electromagnetic handwriting device according to this application, the electromagnetic handwriting device may include a passive electromagnetic pen, an electromagnetic handwriting screen, an electromagnetic induction detection circuit, and an electronic device. The electromagnetic induction detection circuit is the electromagnetic induction detection circuit described in the foregoing circuit embodiment, and the electronic device is the electronic device described in the foregoing device embodiment.

[0125] In this embodiment, multiple leads are evenly arranged in both the horizontal and vertical directions of the electromagnetic handwriting screen. Each pair of leads in the horizontal direction can form an electromagnetic induction coil, and each pair of leads in the vertical direction can also form an electromagnetic induction coil. For example, in some embodiments, the lead arrangement is the same as in the aforementioned circuit embodiment. Figure 4 The arrangement shown is the same.

[0126] When writing on an electromagnetic handwriting screen using a passive electromagnetic pen, the induced current generated by each electromagnetic induction coil on the screen can be detected. The closer the passive electromagnetic pen is to an electromagnetic induction coil, the greater the induced current generated by that coil. Therefore, the position of the electromagnetic induction coil with the largest induced current on the electromagnetic handwriting screen can be obtained, and the writing position of the passive electromagnetic pen on the screen can be determined based on this position. In this embodiment, the electromagnetic induction coil with the largest induced current can be obtained from the horizontal and vertical electromagnetic induction coils of the electromagnetic handwriting screen, and then the writing position of the passive electromagnetic pen can be determined based on the intersection (or overlap) position of these two electromagnetic induction coils.

[0127] In some implementations, the number of electromagnetic induction detection circuits is the same as the total number of electromagnetic induction coils on the electromagnetic handwriting screen. Each electromagnetic induction detection circuit is connected to one electromagnetic induction coil, and each electromagnetic induction detection circuit is used to detect the induced current generated by its respective connected electromagnetic induction coil. Figure 4For example, an electromagnetic handwriting screen has N+1 leads evenly arranged horizontally and M+1 leads evenly arranged vertically. If every two adjacent leads form an electromagnetic induction coil, then M electromagnetic induction coils can be formed horizontally and N electromagnetic induction coils can be formed vertically. Thus, M+N electromagnetic induction detection circuits can be set up.

[0128] In some implementations, there is one electromagnetic induction detection circuit, and a selector switch is provided on the electromagnetic handwriting screen. This selector switch is connected not only to the electromagnetic induction detection circuit but also to the electromagnetic induction coils on the electromagnetic handwriting screen. The selector switch can respond to a control signal to sequentially turn the electrical connection between the electromagnetic induction detection circuit and each electromagnetic induction coil on or off. When the electrical connection between the electromagnetic induction detection circuit and the electromagnetic induction coil is on, electromagnetic induction detection can be performed on the electromagnetic induction coil by the electromagnetic induction detection circuit; when the electrical connection is off, electromagnetic induction detection is not performed on the electromagnetic induction coil. The electromagnetic induction detection includes controlling the excitation drive circuit in the electromagnetic induction detection circuit to transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the drive excitation phase of the detection cycle, and controlling the induction detection circuit to detect the induced current generated by the electromagnetic induction coil during the signal detection phase. Using this selector switch, the induced current generated by each electromagnetic induction coil can be detected sequentially, and then the position of the passive electromagnetic pen on the electromagnetic handwriting screen can be determined based on the induced current generated by each electromagnetic induction coil.

[0129] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. An electromagnetic induction detection circuit for an electromagnetic handwriting device, the electromagnetic handwriting device comprising a passive electromagnetic pen and an electromagnetic handwriting screen, characterized in that, The electromagnetic induction detection circuit includes an excitation drive circuit and an induction detection circuit. The excitation driving circuit is used to: in response to the first driving signal, transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle, stop transmitting the excitation signal during the signal detection phase of the detection cycle, and the electromagnetic induction coil sends out a first electromagnetic signal under the action of the excitation signal. The passive electromagnetic pen is used to: in response to receiving the first electromagnetic signal, convert the first electromagnetic signal into electrical energy for storage; and in response to stopping receiving the first electromagnetic signal, send a second electromagnetic signal to the electromagnetic induction coil according to the stored electrical energy, wherein the electromagnetic induction coil generates an induced current under the action of the second electromagnetic signal. The induction detection circuit is used to: detect the induced current generated by the electromagnetic induction coil in response to the second driving signal during the signal detection phase.

2. The electromagnetic induction detection circuit according to claim 1, characterized in that, The electromagnetic induction detection circuit is disposed on the electromagnetic handwriting screen. Multiple leads are evenly arranged in the horizontal and vertical directions of the electromagnetic handwriting screen. The electromagnetic induction coil is a ring coil formed by two leads on the electromagnetic handwriting screen that are electrically connected to the electromagnetic induction detection circuit. The two leads are two leads in the horizontal or vertical direction of the electromagnetic handwriting screen.

3. The electromagnetic induction detection circuit according to claim 1, characterized in that, The excitation drive circuit includes a signal generation circuit, an excitation capacitor, a first excitation switch, and a second excitation switch. The first excitation switch is connected to a first end of the electromagnetic induction coil, and the second excitation switch is connected to a second end of the electromagnetic induction coil. The signal generation circuit is used to generate a first excitation signal and a second excitation signal, wherein the first excitation signal and the second excitation signal have the same frequency and a phase difference of 180°; The first terminal of the signal generation circuit is connected to the first excitation switch through the excitation capacitor, and the second terminal of the signal generation circuit is connected to the second excitation switch. The first terminal is used to output the first excitation signal, and the second terminal is used to output the second excitation signal.

4. The electromagnetic induction detection circuit according to claim 3, characterized in that, The signal generation circuit includes an excitation signal source, a positive excitation signal amplifier, and a negative excitation signal amplifier; The excitation signal source is used to: output an excitation signal; The output terminal of the excitation signal source is connected to the positive input terminal of the positive excitation signal amplifier, which is used to amplify the excitation signal in phase to form the first excitation signal. The output terminal of the excitation signal source is also connected to the negative input terminal of the negative excitation signal amplifier, which is used to invert and amplify the excitation signal to form the second excitation signal. The first and second terminals of the signal generation circuit are the output terminals of the positive excitation signal amplifier and the negative excitation signal amplifier, respectively.

5. The electromagnetic induction detection circuit according to claim 3, characterized in that, The excitation capacitor and the electromagnetic induction coil form a first resonant circuit, and the inductive inductor and storage capacitor in the passive electromagnetic pen form a second resonant circuit. The resonant frequency of the first resonant circuit and the resonant frequency of the second resonant circuit are the same as the frequency of the first excitation signal.

6. The electromagnetic induction detection circuit according to claim 1, characterized in that, The sensing detection circuit includes a first detection switch, a second detection switch, a coupling capacitor, and a signal detection circuit. The first detection switch is connected to a first end of the electromagnetic induction coil, and the second detection switch is connected to a second end of the electromagnetic induction coil. The first terminal of the signal detection circuit is connected to the first detection switch through the coupling capacitor, and the second terminal of the signal detection circuit is connected to the second detection switch; The signal detection circuit includes a detection resistor, which is used to detect and output the voltage signal generated by the induced current across the detection resistor.

7. The electromagnetic induction detection circuit according to claim 6, characterized in that, The signal detection circuit further includes a current amplifier and a feedback capacitor, and the first terminal and the second terminal of the signal detection circuit are respectively the negative input terminal and the positive input terminal of the current amplifier; The two ends of the detection resistor are connected to the negative input terminal and the output terminal of the current amplifier, respectively, and the feedback capacitor is connected in parallel with the detection resistor.

8. The electromagnetic induction detection circuit according to claim 6 or 7, characterized in that, The sensing detection circuit also includes a filter circuit and a bandpass amplifier circuit; The filtering circuit is used to: filter the voltage signal output by the signal detection circuit to obtain a filtered voltage signal; The bandpass amplifier circuit is used to amplify the filtered voltage signal whose frequency is within a preset bandpass frequency range to obtain an amplified voltage signal.

9. The electromagnetic induction detection circuit according to claim 8, characterized in that, The inductor and storage capacitor in the passive electromagnetic pen form a second resonant circuit, and the center frequency of the preset passband range, the resonant frequency of the second resonant circuit, and the frequency of the excitation signal are the same.

10. The electromagnetic induction detection circuit according to claim 8, characterized in that, The bandpass amplifier circuit includes a bandpass amplifier, a first resistor, a second resistor, a first capacitor, and a second capacitor. The first end of the first resistor is connected to the filter circuit, the second end of the first resistor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the negative input terminal of the bandpass amplifier, and the positive input terminal of the bandpass amplifier is grounded. The two ends of the second resistor are connected to the negative input and output of the bandpass amplifier, respectively. The first end of the second capacitor is connected between the first resistor and the first capacitor, and the second end of the second capacitor is connected to the output of the bandpass amplifier.

11. The electromagnetic induction detection circuit according to claim 10, characterized in that, The minimum and maximum cutoff frequencies of the preset passband range are respectively and ; , , and These represent the resistance values ​​of the first resistor and the second resistor, respectively. and These represent the capacitance values ​​of the first capacitor and the second capacitor, respectively.

12. A driving method for an electromagnetic induction detection circuit, characterized in that, The electromagnetic induction detection circuit is the electromagnetic induction detection circuit for an electromagnetic handwriting device as described in any one of claims 1 to 11, and the method includes: The electromagnetic induction detection circuit is periodically output with a circuit drive signal. The circuit driving signal includes a first driving signal and a second driving signal. The first driving signal includes a first level signal and a second level signal. The first level signal is used to control the excitation driving circuit in the electromagnetic induction detection circuit to transmit an excitation signal to the electromagnetic induction coil on the electromagnetic handwriting screen during the driving excitation phase of the detection cycle. The second level signal is used to control the excitation driving circuit to stop transmitting the excitation signal during the signal detection phase of the detection cycle. The level value of the first level signal is greater than the level value of the second level signal. The second driving signal includes a third level signal and a fourth level signal. The third level signal is used to control the induction detection circuit in the electromagnetic induction detection circuit to stop detecting the induced current generated by the electromagnetic induction coil during the driving excitation phase. The fourth level signal is used to control the induction detection circuit to detect the induced current generated by the electromagnetic induction coil during the signal detection phase. The level value of the third level signal is lower than the level value of the fourth level signal.

13. An electronic device, characterized in that, include: At least one processor; as well as, A memory that is communicatively connected to the at least one processor; The memory stores a computer program, which, when executed by the at least one processor, implements the driving method of the electromagnetic induction detection circuit according to claim 12.

14. An electromagnetic handwriting device, comprising a passive electromagnetic pen and an electromagnetic handwriting screen, characterized in that, The electromagnetic handwriting device further includes an electromagnetic induction detection circuit for the electromagnetic handwriting device according to any one of claims 1 to 11, and an electronic device according to claim 13.

15. A computer-readable storage medium storing a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by a processor to perform the driving method of the electromagnetic induction detection circuit of claim 12.

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