Electromagnetic pen, induction device for electromagnetic pen, display device, and electromagnetic pen system
By monitoring and adjusting the resonant frequency of the electromagnetic pen's resonant circuit using a sensing device, the problem of electromagnetic noise interference was solved, improving the signal-to-noise ratio and reliability of the electromagnetic pen.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BOE TECHNOLOGY GROUP CO LTD
- Filing Date
- 2026-04-28
- Publication Date
- 2026-07-21
AI Technical Summary
When the frequency of electromagnetic noise approaches the resonant frequency of the resonant circuit inside the electromagnetic pen, the signal-to-noise ratio decreases, affecting the normal operation of the electromagnetic pen.
The electromagnetic pen monitors ambient electromagnetic noise using sensing devices, sends frequency switching signals to adjust the resonant frequency of the resonant circuit inside the electromagnetic pen, and makes it avoid the noise frequency band. The resonant frequency is dynamically adjusted using a variable capacitor unit and a control unit.
It effectively reduces electromagnetic noise interference, improves the signal-to-noise ratio of the electromagnetic pen signal, and enhances the reliability of the electromagnetic pen.
Smart Images
Figure CN122431541A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electromagnetic handwriting technology, specifically providing an electromagnetic pen, a sensing device for the electromagnetic pen, a display device, and an electromagnetic pen system. Background Technology
[0002] When the electromagnetic pen is moved on the electromagnetic handwriting screen, the antenna board on the screen sends an excitation signal. The electromagnetic pen receives this excitation signal, and the resonant circuit inside the pen resonates under the excitation signal, allowing the pen to store electromagnetic energy. When the antenna board stops sending the excitation signal, the resonant circuit inside the pen continues to resonate using the stored electromagnetic energy, allowing the pen to send electromagnetic signals outward, which the antenna board can receive.
[0003] Currently, the resonant frequency of the internal resonant circuit of an electromagnetic pen is basically fixed. Only when pressure is detected or the pen's button is pressed will the internal capacitance (i.e., the capacitance forming the resonant circuit) be affected, causing the resonant frequency to vary within a small range. When displaying specific images (such as high brightness, checkerboard patterns, or specific refresh rates), electromagnetic handwriting screens generate electromagnetic noise of specific frequencies. If the frequency of this electromagnetic noise is close to the resonant frequency of the internal resonant circuit, the circuit's signal response to this noise will be very strong, resulting in a high signal-to-noise ratio at the circuit's output, which affects the normal operation of the electromagnetic pen.
[0004] Accordingly, a new technical solution is needed in this field to solve the above problems. Summary of the Invention
[0005] This application aims to solve the above-mentioned technical problems, namely, to solve or at least partially solve the following technical problems: how to reduce or avoid the interference of electromagnetic noise on electromagnetic pens and improve the reliability of electromagnetic pens.
[0006] In a first aspect, this application provides an electromagnetic pen, the electromagnetic pen comprising:
[0007] Resonant circuit;
[0008] A first control unit is configured to monitor the signal received by the electromagnetic pen, and when the signal is a frequency switching signal, adjust the resonant frequency of the resonant circuit according to the frequency switching signal so that the resonant frequency falls outside the frequency band of the ambient electromagnetic noise.
[0009] The frequency switching signal is a signal sent by the sensing device to the electromagnetic pen when it detects that the ambient electromagnetic noise meets a preset condition.
[0010] In one technical solution of the electromagnetic pen mentioned above, the preset conditions include the frequency of the environmental electromagnetic noise being within the target range and the intensity of the environmental electromagnetic noise being greater than a set threshold.
[0011] The target range is a preset range centered on the frequency of the signal emitted by the electromagnetic pen.
[0012] In one of the above-mentioned technical solutions for the electromagnetic pen, the preset conditions further include that the duration of the ambient electromagnetic noise is greater than a set duration and that the ambient electromagnetic noise is narrowband noise.
[0013] In one technical solution of the electromagnetic pen described above, the resonant circuit includes a resonant coil and a variable capacitor unit. Adjusting the resonant frequency of the resonant circuit according to the frequency switching signal includes: adjusting the capacitance value of the variable capacitor unit according to the frequency switching signal, so as to change the resonant frequency of the resonant circuit by adjusting the capacitance value.
[0014] In one technical solution of the above-mentioned electromagnetic pen, the variable capacitor unit is a digital capacitor array, and adjusting the capacitance value of the variable capacitor unit according to the frequency switching signal includes:
[0015] The frequency switching signal is decoded to obtain the capacitor combination method, which is used to indicate the capacitors in the digital capacitor array that are electrically connected to the resonant coil.
[0016] The capacitor indicated by the control capacitor combination mode is electrically connected to the resonant coil to change the capacitance value of the digital capacitor array.
[0017] In one technical solution of the aforementioned electromagnetic pen, the variable capacitor unit includes a varactor diode and a digital-to-analog converter. Adjusting the capacitance value of the variable capacitor unit according to the frequency switching signal includes:
[0018] The frequency switching signal is decoded to obtain capacitor control information in digital signal form;
[0019] The digital-to-analog converter is used to convert the capacitor control information into a voltage signal;
[0020] The voltage applied across the varactor diode is adjusted to the voltage signal to change the capacitance value of the varactor diode.
[0021] In one technical solution of the electromagnetic pen described above, the monitoring of the signal received by the electromagnetic pen includes: monitoring the signal received by the electromagnetic pen within a specific time window during each working cycle of the electromagnetic pen.
[0022] In a second aspect, this application provides a sensing device for an electromagnetic pen, the sensing device comprising:
[0023] The second control unit is configured to send a frequency switching signal to the electromagnetic pen when it detects that the ambient electromagnetic noise meets a preset condition.
[0024] The electromagnetic pen includes a resonant circuit, and the frequency switching signal is used to adjust the resonant frequency of the resonant circuit so that the resonant frequency falls outside the frequency band of ambient electromagnetic noise.
[0025] In one technical solution of the above-mentioned sensing device, the sensing device further includes an electromagnetic antenna board, which is configured to receive signals emitted by the electromagnetic pen and collect environmental electromagnetic noise.
[0026] The preset conditions include the frequency of the environmental electromagnetic noise being within the target range and the intensity of the environmental electromagnetic noise being greater than a set threshold, wherein the target range is a preset range centered on the frequency of the signal emitted by the electromagnetic pen; or, the preset conditions include the frequency of the environmental electromagnetic noise being within the target range, and the intensity of the environmental electromagnetic noise being greater than a set threshold, the duration being greater than a set duration, and the environmental electromagnetic noise being narrowband noise.
[0027] In one technical solution of the above-mentioned sensing device, the frequency switching signal sent to the electromagnetic pen includes: sending a frequency switching signal to the electromagnetic pen during a specific time window within one working cycle of the electromagnetic pen.
[0028] In one technical solution of the above-mentioned sensing device, the resonant circuit of the electromagnetic pen includes a resonant coil and a variable capacitor unit;
[0029] The second control unit is also configured to:
[0030] The resonant frequency of the resonant circuit is determined based on the frequency band of the ambient electromagnetic noise, the capacitance value of the variable capacitor unit in the resonant circuit is determined based on the adjusted resonant frequency, and the frequency switching signal is generated based on the capacitance value.
[0031] In one technical solution of the aforementioned sensing device, when the variable capacitor unit is a digital capacitor array, generating the frequency switching signal based on the capacitance value includes:
[0032] The capacitance combination method of the digital capacitor array is determined based on the capacitance value, and the capacitance combination method is used to indicate the capacitors in the digital capacitor array that are electrically connected to the resonant coil.
[0033] The frequency switching signal is generated according to the capacitor combination method.
[0034] In one technical solution of the aforementioned sensing device, when the variable capacitor unit includes a varactor diode and a digital-to-analog converter, generating the frequency switching signal based on the capacitance value includes:
[0035] Based on the capacitance value, determine the voltage signal to be applied across the varactor diode;
[0036] The voltage signal is converted into digital signal form of capacitor control information;
[0037] The frequency switching signal is generated based on the capacitor control information.
[0038] In a third aspect, this application provides a display device, which includes the sensing device described in any of the technical solutions provided in the second aspect above.
[0039] In a fourth aspect, this application provides an electromagnetic pen system, the system including the electromagnetic pen described in any of the technical solutions provided in the first aspect above, and the sensing device described in any of the technical solutions provided in the second aspect above;
[0040] Alternatively, the system may include the electromagnetic pen described in any of the technical solutions provided in the first aspect, and the display device provided in the third aspect.
[0041] The above-described technical solutions of this application have at least one or more of the following beneficial effects:
[0042] In one embodiment of the electromagnetic pen provided in this application, the electromagnetic pen may include a resonant circuit and a first control unit. The first control unit may be configured to monitor the signal received by the electromagnetic pen, and when the received signal is a frequency switching signal, adjust the resonant frequency of the resonant circuit according to the frequency switching signal so that the resonant frequency falls outside the frequency band where the ambient electromagnetic noise is located, i.e., avoids that frequency band; wherein, the frequency switching signal is a signal sent to the electromagnetic pen by the sensing device when it detects that the ambient electromagnetic noise meets a preset condition.
[0043] Based on the above implementation scheme, the resonant frequency of the resonant circuit can be dynamically adjusted according to the frequency of the ambient electromagnetic noise, thereby reducing or avoiding the interference of electromagnetic noise on the electromagnetic pen, improving the signal-to-noise ratio (SNR) of the signal emitted by the electromagnetic pen, and thus improving the reliability of the electromagnetic pen. Attached Figure Description
[0044] 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:
[0045] Figure 1 This is a schematic diagram of the main structure of the electromagnetic pen in some embodiments of this application;
[0046] Figure 2 This is a schematic diagram of the main structure of the sensing device in some embodiments of this application;
[0047] Figure 3 This is a schematic flowchart illustrating the main steps of adjusting the resonant frequency of an electromagnetic pen based on a sensing device in some embodiments of this application.
[0048] Figure label:
[0049] 11: Resonant circuit; 12: First control unit; 21: Second control unit. Detailed Implementation
[0050] 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.
[0051] First, an embodiment of the electromagnetic pen provided in this application will be described.
[0052] See appendix Figure 1 , Figure 1 This is a schematic diagram of the main structure of the electromagnetic pen in some embodiments of this application. For example... Figure 1 As shown, in this embodiment of the application, the electromagnetic pen may include a resonant circuit 11 and a first control unit 12, and these two structures will be described below.
[0053] 1. The resonant circuit 11 is described.
[0054] In this embodiment, the electromagnetic pen and the electromagnetic handwriting screen can be combined to form an electromagnetic handwriting device. When the user moves the electromagnetic pen on the electromagnetic handwriting screen, the electromagnetic pen can receive the first electromagnetic signal sent by the electromagnetic induction coil on the electromagnetic handwriting screen. Under the excitation of the first electromagnetic signal, the resonant circuit 11 in the electromagnetic pen can resonate, generating a resonant voltage and a resonant current. Based on the resonant voltage and resonant current, the energy of the electromagnetic signal can be converted into electrical energy for storage.
[0055] When the electromagnetic induction coil on the electromagnetic handwriting screen stops sending the first electromagnetic signal, the resonant circuit 11 inside the electromagnetic pen can continue to resonate using the stored electrical energy, sending out a second electromagnetic signal. The electromagnetic induction coil on the electromagnetic handwriting screen can generate an induced current under the action of the second electromagnetic signal. As the stored electrical energy decreases, the resonant voltage and resonant current generated by the resonant circuit 11 inside the electromagnetic pen will also gradually decrease. When the stored electrical energy is completely converted into the second electromagnetic signal and sent out, the resonant voltage and resonant current will drop to zero.
[0056] The closer the electromagnetic pen is to a certain electromagnetic induction coil on the electromagnetic handwriting screen, the stronger the energy of the first electromagnetic signal sent by that electromagnetic induction coil will be, and the stronger the energy of the second electromagnetic signal sent to that electromagnetic induction coil will be. The induced current generated by that electromagnetic induction coil will also be greater. Therefore, the position of the passive electromagnetic pen on the electromagnetic handwriting screen can be determined by the magnitude of the induced current generated by each electromagnetic induction coil on the electromagnetic handwriting screen.
[0057] This application does not specifically limit the type of electromagnetic handwriting screen. For example, the electromagnetic handwriting screen can be an electromagnetic handwriting screen using OLED (Organic Light Emitting Diode).
[0058] 2. The first control unit 12 will be described.
[0059] In this embodiment, the first control unit 12 can be configured to monitor the signal received by the electromagnetic pen. When the signal received by the electromagnetic pen is a frequency switching signal, the resonant frequency of the resonant circuit 11 inside the electromagnetic pen is adjusted according to the frequency switching signal so that the resonant frequency falls outside the frequency band where the environmental electromagnetic noise is located, even if the resonant frequency avoids the frequency band.
[0060] The frequency switching signal is a signal sent by the sensing device to the electromagnetic pen when it detects that the ambient electromagnetic noise meets a preset condition. The sensing device can be installed on the electromagnetic handwriting screen and can detect ambient electromagnetic noise in real time, sending a frequency switching signal to the electromagnetic pen when the ambient electromagnetic noise meets the preset condition. Ambient electromagnetic noise can include electromagnetic noise generated by the electromagnetic handwriting screen when displaying images. For example, the electromagnetic handwriting screen may generate electromagnetic noise of a specific frequency when displaying high-brightness, checkerboard, or specific refresh rate images.
[0061] In some embodiments of this application, the aforementioned preset conditions may include the frequency of the ambient electromagnetic noise being within a target range and the intensity of the ambient electromagnetic noise being greater than a set threshold. The target range is a preset range centered on the frequency of the signal emitted by the electromagnetic pen (i.e., the operating frequency of the electromagnetic pen).
[0062] If the ambient electromagnetic noise meets the aforementioned preset conditions, it indicates that high-intensity ambient electromagnetic noise has appeared near the operating frequency of the electromagnetic pen. This ambient electromagnetic noise will interfere with the electromagnetic pen, causing a decrease in the signal-to-noise ratio (SNR) of the signal emitted by the pen. Therefore, when the ambient electromagnetic noise meets the aforementioned preset conditions, a frequency switching signal can be sent to the electromagnetic pen. The first control unit 12 inside the electromagnetic pen will adjust the resonant frequency of the resonant circuit 11 inside the electromagnetic pen (this resonant frequency is the same as the frequency of the signal emitted by the electromagnetic pen, and this resonant frequency can also be understood as the operating frequency of the electromagnetic pen) to be outside the frequency band where the ambient electromagnetic noise is located. In this way, the ambient electromagnetic noise will not interfere with the electromagnetic pen, thereby improving the signal-to-noise ratio of the signal emitted by the pen.
[0063] In some embodiments of this application, the aforementioned preset conditions may include, in addition to the frequency of the ambient electromagnetic noise being within the target range and the intensity of the ambient electromagnetic noise being greater than a set threshold, the duration of the ambient electromagnetic noise being greater than a set duration and the ambient electromagnetic noise being narrowband noise. If the ambient electromagnetic noise meets these preset conditions, it indicates that high-intensity, long-duration narrowband electromagnetic noise has appeared near the operating frequency of the electromagnetic pen, and this noise will cause a sharp drop in the signal-to-noise ratio of the signal emitted by the magnetic pen. Therefore, when the ambient electromagnetic noise meets these preset conditions, a frequency switching signal can be sent to the electromagnetic pen to improve the signal-to-noise ratio of the signal emitted by the magnetic pen.
[0064] In some embodiments of this application, when the first control unit 12 monitors the signal received by the electromagnetic pen, it can monitor the signal received by the electromagnetic pen within a specific time window in each working cycle of the electromagnetic pen. The specific time window can be a pre-set uplink signal transmission window, in which the uplink device of the electromagnetic pen can send a signal (i.e., the uplink signal) to the electromagnetic pen. In the embodiments of this application, the sensing device, as the uplink device of the electromagnetic pen, will also send a frequency switching signal to the electromagnetic pen within this window. Therefore, the first control unit 12 can monitor the signal received by the electromagnetic pen within this window and can detect the frequency switching signal in a timely manner.
[0065] In some embodiments of this application, the first control unit 12 may include a low-power chip that monitors the signals received by the electromagnetic pen and adjusts the resonant frequency of the resonant circuit according to the frequency switching signal when a frequency switching signal is received. Based on this, the power consumption of the electromagnetic pen can be reduced. Furthermore, when the electromagnetic pen transmits electromagnetic signals (i.e., downlink signals), it can adopt a passive electromagnetic pen operating mode to transmit electromagnetic signals, further reducing the power consumption of the electromagnetic pen.
[0066] Low-power chips may include MCUs (Micro Control Units). The MCU can adjust the resonant frequency of the resonant circuit via its own GPIO (General Purpose Input / Output) pins (such as I²C or SPI interfaces). For example, the resonant circuit 11 may include a resonant coil and a variable capacitor unit. The MCU can adjust the capacitance value of the variable capacitor unit via GPIO pins to change the resonant frequency of the resonant circuit. The method of changing the resonant frequency by adjusting the capacitance value of the variable capacitor unit will be described in subsequent embodiments and will not be repeated here.
[0067] In this embodiment of the application, after adjusting the resonant frequency of the resonant circuit, it is necessary to simultaneously adjust the driving frequency of the resonant circuit to the new resonant frequency after the resonant circuit is adjusted. The driving frequency refers to the frequency of the driving signal that drives the resonant coil in the resonant circuit.
[0068] Based on the above structure of the embodiments of this application, the electromagnetic pen can dynamically adjust the resonant frequency of the resonant circuit 11 according to the frequency of the ambient electromagnetic noise, thereby reducing or avoiding the interference of electromagnetic noise on the electromagnetic pen, improving the signal-to-noise ratio of the signal emitted by the electromagnetic pen, and thus improving the reliability of the electromagnetic pen.
[0069] The following description continues with an embodiment of the electromagnetic pen provided in this application, specifically describing the method by which the first control unit 12 adjusts the resonant frequency of the resonant circuit 11.
[0070] In some embodiments of this application, the resonant circuit 11 may include a resonant coil and a variable capacitor unit, and the first control unit 12 may be configured to adjust the capacitance value of the variable capacitor unit according to the frequency switching signal, so as to change the resonant frequency of the resonant circuit by adjusting the capacitance value.
[0071] The resonant frequency of the resonant circuit can be calculated using the following formula (1):
[0072] (1)
[0073] The meanings of the parameters in formula (1) are as follows: Indicates the resonant frequency. This represents the inductance value of the resonant coil. This represents the resonant capacitor. The capacitance value is the same as that of the variable capacitor unit. Adjusting the capacitance value of the variable capacitor unit is equivalent to adjusting the resonant capacitance. resonant capacitor After being changed, the resonant frequency And so it changed.
[0074] The following description continues with an embodiment of the electromagnetic pen provided in this application, specifically describing the method by which the first control unit 12 adjusts the capacitance value of the variable capacitor unit.
[0075] In some embodiments of this application, the variable capacitor unit may be a digital capacitor array (DCA), and the first control unit 12 may be configured to adjust the capacitance value of the variable capacitor unit through the following steps 11 to 12.
[0076] Step 11: Decode the frequency switching signal to obtain the capacitor combination mode. The capacitor combination mode is used to indicate the capacitors that are electrically connected to the resonant coil in the digital capacitor array.
[0077] In this embodiment, when the sensing device detects that the ambient electromagnetic noise meets preset conditions, it can determine a capacitor combination that ensures the resonant frequency falls outside the frequency band of the ambient electromagnetic noise based on the frequency band of the ambient electromagnetic noise and the operating frequency of the electromagnetic pen (i.e., the resonant frequency of the resonant circuit). Then, it generates a digital instruction (i.e., the instruction is a digital signal) to indicate this capacitor combination. This digital instruction is encoded to obtain a frequency switching signal, which is then sent to the electromagnetic pen. In this embodiment, conventional amplitude, phase, or frequency keying methods can be used to encode the digital instruction so that the encoded result (i.e., the frequency switching signal) can be transmitted to the electromagnetic pen in the form of an electromagnetic signal. For example, Amplitude Shift Keying (ASK) or Frequency Shift Keying (FSK) methods can be used to encode the digital instruction. Furthermore, in this embodiment, different capacitor combinations correspond to different resonant frequencies. By increasing the encoding length, more selectable capacitor combinations can be added to adapt to more complex noise environments.
[0078] The first control unit 12 can decode the frequency switching signal to obtain a digital instruction. If this digital instruction is used to indicate the capacitor combination method, then the capacitor combination method indicated by the digital instruction can be obtained. For example, in some embodiments, the digital instruction obtained by decoding the frequency switching signal can be one of the following Table 1:
[0079] Table 1
[0080] 00 Indicator capacitor combination method A 01 Indicator capacitor combination method B 10 Indicator capacitor combination method C 11 Without changing the capacitor configuration, i.e., keeping the current operating frequency unchanged.
[0081] Step 12: Connect the capacitor indicated by the control capacitor combination mode to the resonant coil to change the capacitance value of the digital capacitor array.
[0082] Based on the methods described in steps 11 to 12 above, the capacitance value of the digital capacitor array can be adjusted conveniently and accurately when the variable capacitor unit adopts a digital capacitor array.
[0083] The following description continues with the embodiment of the electromagnetic pen provided in this application, focusing on the method by which the first control unit 12 adjusts the capacitance value of the variable capacitor unit.
[0084] In some embodiments of this application, the variable capacitor unit may include varactor diodes and a digital to analog converter (DAC), and the first control unit 12 may be configured to adjust the capacitance value of the variable capacitor unit through the following steps 21 to 23.
[0085] Step 21: Decode the frequency switching signal to obtain the capacitor control information in digital signal form.
[0086] In this embodiment, when the sensing device detects that the ambient electromagnetic noise meets preset conditions, it can determine the capacitance value of the resonant capacitor that ensures the resonant frequency falls outside the frequency band of the ambient electromagnetic noise, based on the frequency band of the ambient electromagnetic noise and the operating frequency of the electromagnetic pen (i.e., the resonant frequency of the resonant circuit). Then, based on the capacitance value of the resonant capacitor, it determines the control voltage (i.e., the diode bias voltage) of the varactor diode in the variable capacitor unit. This control voltage is used to adjust the capacitance value of the varactor diode to the capacitance value of the resonant capacitor. A digital signal of capacitor control information (i.e., the signal is digital) is then generated based on this control voltage. This capacitor control information is encoded to obtain a frequency switching signal, which is then sent to the electromagnetic pen. The encoding method is similar to that in step 11 above and will not be described again.
[0087] The first control unit 12 decodes the frequency switching signal to obtain the aforementioned capacitor control information.
[0088] Step 22: Use a digital-to-analog converter to convert the capacitor control information into a voltage signal. This voltage signal is the control voltage of the varactor diode determined by the sensing device in step 21 above.
[0089] Step 23: Adjust the voltage applied across the varactor diode to the voltage signal obtained in step 22 to change the capacitance value of the varactor diode.
[0090] The changed capacitance value of the varactor diode is the capacitance value of the resonant capacitor in step 11 above, which enables the resonant frequency to fall outside the frequency band of the ambient electromagnetic noise.
[0091] Based on the methods described in steps 21 to 23 above, the capacitance value of the varactor diode can be adjusted conveniently and accurately when the varactor diode is used in the variable capacitor unit.
[0092] The following describes an embodiment of the sensing device for an electromagnetic pen provided in this application.
[0093] See appendix Figure 2 , Figure 2 This is a schematic diagram of the main structure of the sensing device in some embodiments of this application. For example... Figure 2 As shown, in this embodiment of the application, the sensing device may include a second control unit 21. The second control unit 21 may be configured to send a frequency switching signal to the electromagnetic pen when the detected ambient electromagnetic noise meets a preset condition. The preset condition is the same as the preset condition in the aforementioned electromagnetic pen embodiment, and will not be repeated here.
[0094] The electromagnetic pen may include a resonant circuit. A frequency switching signal is used to adjust the resonant frequency of the resonant circuit so that the resonant frequency falls outside the frequency band of ambient electromagnetic noise. The resonant circuit is the same as the resonant circuit 11 in the aforementioned electromagnetic pen embodiment, and will not be described again here.
[0095] In some embodiments of this application, the sensing device may further include an electromagnetic antenna board, which may be configured to receive signals emitted by the electromagnetic pen and collect ambient electromagnetic noise.
[0096] In some embodiments of this application, the sensing device sends a frequency switching signal to the electromagnetic pen within a specific time window of one working cycle of the electromagnetic pen. Based on this, the first control unit 12 within the electromagnetic pen can monitor the signals received by the electromagnetic pen within specific time windows of each working cycle of the electromagnetic pen.
[0097] In some embodiments of this application, the resonant circuit 11 of the electromagnetic pen may include a resonant coil and a variable capacitor unit. The second control unit 21 within the sensing device may also be configured to: determine the adjusted resonant frequency of the resonant circuit based on the frequency band of the ambient electromagnetic noise; determine the capacitance value of the variable capacitor unit within the resonant circuit based on the adjusted resonant frequency; and generate a frequency switching signal based on the capacitance value. The first control unit 11 within the electromagnetic pen may decode the frequency switching signal to obtain the capacitance value and adjust the capacitance value of the variable capacitor unit to the decoded capacitance value.
[0098] In some embodiments of this application, the variable capacitor unit in the electromagnetic pen is a digital capacitor array, and the second control unit 21 in the sensing device can be configured to generate a frequency switching signal through the following steps 31 to 32.
[0099] Step 31: Determine the capacitor combination method of the digital capacitor array based on the capacitance value. The capacitor combination method is used to indicate the capacitors in the digital capacitor array that are electrically connected to the resonant coil.
[0100] The capacitor combination method has the same meaning as the capacitor combination method in the aforementioned electromagnetic pen embodiment.
[0101] Step 32: Generate a frequency switching signal based on the capacitor combination method.
[0102] Specifically, a digital pointer (i.e., the instruction is a digital signal) can be generated to indicate the capacitor combination method, and this digital instruction is encoded to obtain a frequency switching signal. In the embodiments of this application, conventional amplitude, phase, or frequency keying methods can be used to encode the digital instruction so that the frequency switching signal can be transmitted to the electromagnetic pen in the form of an electromagnetic signal. For example, amplitude keying or frequency shift keying methods can be used to encode the above-mentioned digital instruction.
[0103] Based on the methods described in steps 31 to 32 above, a frequency switching signal can be reliably generated when the variable capacitor unit uses a digital capacitor array, thereby using the frequency switching signal to conveniently and accurately adjust the capacitance value of the digital capacitor array.
[0104] In some embodiments of this application, the variable capacitor unit in the electromagnetic pen includes a varactor diode and a digital-to-analog converter, and the second control unit 21 in the sensing device can be configured to generate a frequency switching signal through the following steps 41 to 43.
[0105] Step 41: Determine the voltage signal to be applied across the varactor diode (i.e., the diode bias voltage) based on the capacitance value. Step 42: Convert the voltage signal into digital capacitance control information. Step 43: Generate a frequency switching signal based on the capacitance control information. Specifically, the capacitance control information can be encoded to obtain the frequency switching signal, which is then sent to the electromagnetic pen. The encoding method is similar to that in step 32 above and will not be repeated here.
[0106] Based on the methods described in steps 41 to 43 above, a frequency switching signal can be reliably generated when a varactor diode is used in the variable capacitor unit, thereby conveniently and accurately adjusting the capacitance value of the varactor diode using the frequency switching signal.
[0107] The following describes embodiments of the display device provided in this application.
[0108] In some embodiments of this application, the display device may include a screen and the sensing device described in the foregoing sensing device embodiments. The display device may be a mobile phone, tablet computer, desktop computer, laptop computer, handheld computer, notebook computer, super mobile personal computer, netbook, personal digital assistant, etc., and this embodiment does not specifically limit it.
[0109] The following describes an embodiment of the electromagnetic pen system provided in this application.
[0110] In some embodiments of this application, the electromagnetic pen system may include the electromagnetic pen described in the aforementioned electromagnetic pen embodiments and the display device described in the aforementioned display device embodiments, wherein the display device includes the sensing device described in the aforementioned sensing device embodiments.
[0111] In some embodiments of this application, the electromagnetic pen system may include the electromagnetic pen described in the foregoing electromagnetic pen embodiments and the sensing device described in the foregoing sensing device embodiments. The sensing device may be disposed on an electromagnetic handwriting screen or a display device.
[0112] The following is in conjunction with the appendix Figure 3 The electromagnetic pen system in the embodiments of this application will be described.
[0113] like Figure 3 As shown, the electromagnetic pen system can adjust the resonant frequency of the electromagnetic pen based on the sensing device and through the following steps S101 to S104.
[0114] Step S101: The sensing device detects ambient electromagnetic noise. Step S102: When the ambient electromagnetic noise meets the preset conditions, the sensing device sends a frequency switching signal to the electromagnetic pen.
[0115] Step S103: The electromagnetic pen adjusts the resonant frequency of its internal resonant circuit according to the frequency switching signal. Specifically, if the electromagnetic pen receives the frequency switching signal in the kth working cycle, it determines the adjusted resonant frequency of the resonant circuit (hereinafter referred to as the new frequency) based on the frequency switching signal, and then adjusts the resonant frequency of the resonant circuit to this new frequency starting from the (k+1)th working cycle, where k represents the sequence number of any working cycle of the electromagnetic pen.
[0116] Step S104: New frequency confirmation and synchronization.
[0117] Specifically, starting from the (k+1)th working cycle of the electromagnetic pen, the sensing device acquires the first signal-to-noise ratio of the signal emitted by the electromagnetic pen, and compares the first signal-to-noise ratio with the second signal-to-noise ratio, which is the signal-to-noise ratio of the electromagnetic pen emitted when the ambient electromagnetic noise meets the preset conditions.
[0118] If the first signal-to-noise ratio (SNR) is greater than the second SNR, and the deviation between the first and second SNRs is greater than a set threshold, it indicates that the SNR has been significantly improved and the new frequency can be maintained. Otherwise, it indicates that the SNR has not been significantly improved, and a frequency switching signal is regenerated based on the real-time detected environmental electromagnetic noise. Then, steps S103 and S104 are executed. The method for regenerating the frequency switching signal based on the real-time detected environmental electromagnetic noise is the same as the method for generating the frequency switching signal in step S102 when the environmental electromagnetic noise meets the preset conditions.
[0119] Based on the above steps S101 to S104, the resonant frequency of the resonant circuit can be dynamically adjusted according to the frequency of the environmental electromagnetic noise, thereby reducing or avoiding the interference of electromagnetic noise on the electromagnetic pen, improving the signal-to-noise ratio of the signal emitted by the electromagnetic pen, and thus improving the reliability of the electromagnetic pen.
[0120] The technical solutions of this application have been described above with reference to the optional 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 pen, characterized in that, The electromagnetic pen includes: Resonant circuit; A first control unit is configured to monitor the signal received by the electromagnetic pen, and when the signal is a frequency switching signal, adjust the resonant frequency of the resonant circuit according to the frequency switching signal so that the resonant frequency falls outside the frequency band of the ambient electromagnetic noise. The frequency switching signal is a signal sent by the sensing device to the electromagnetic pen when it detects that the ambient electromagnetic noise meets a preset condition.
2. The electromagnetic pen according to claim 1, characterized in that, The preset conditions include that the frequency of the environmental electromagnetic noise is within the target range and the intensity of the environmental electromagnetic noise is greater than a set threshold. The target range is a preset range centered on the frequency of the signal emitted by the electromagnetic pen.
3. The electromagnetic pen according to claim 2, characterized in that, The preset conditions also include that the duration of the environmental electromagnetic noise is greater than a set duration and that the environmental electromagnetic noise is narrowband noise.
4. The electromagnetic pen according to claim 1, characterized in that, The resonant circuit includes a resonant coil and a variable capacitor unit. Adjusting the resonant frequency of the resonant circuit according to the frequency switching signal includes: The capacitance value of the variable capacitor unit is adjusted according to the frequency switching signal, so as to change the resonant frequency of the resonant circuit by adjusting the capacitance value.
5. The electromagnetic pen according to claim 4, characterized in that, The variable capacitor unit is a digital capacitor array, and adjusting the capacitance value of the variable capacitor unit according to the frequency switching signal includes: The frequency switching signal is decoded to obtain the capacitor combination method, which is used to indicate the capacitors in the digital capacitor array that are electrically connected to the resonant coil. The capacitor indicated by the control capacitor combination mode is electrically connected to the resonant coil to change the capacitance value of the digital capacitor array.
6. The electromagnetic pen according to claim 4, characterized in that, The variable capacitor unit includes a varactor diode and a digital-to-analog converter. Adjusting the capacitance value of the variable capacitor unit according to the frequency switching signal includes: The frequency switching signal is decoded to obtain capacitor control information in digital signal form; The digital-to-analog converter is used to convert the capacitor control information into a voltage signal; The voltage applied across the varactor diode is adjusted to the voltage signal to change the capacitance value of the varactor diode.
7. The electromagnetic pen according to claim 1, characterized in that, The monitoring of the signals received by the electromagnetic pen includes: monitoring the signals received by the electromagnetic pen within specific time windows of each working cycle of the electromagnetic pen.
8. A sensing device for an electromagnetic pen, characterized in that, The sensing device includes: The second control unit is configured to send a frequency switching signal to the electromagnetic pen when it detects that the ambient electromagnetic noise meets a preset condition. The electromagnetic pen includes a resonant circuit, and the frequency switching signal is used to adjust the resonant frequency of the resonant circuit so that the resonant frequency falls outside the frequency band of ambient electromagnetic noise.
9. The sensing device according to claim 8, characterized in that, The sensing device also includes an electromagnetic antenna board, which is configured to receive signals emitted by the electromagnetic pen and collect ambient electromagnetic noise. The preset conditions include the frequency of the environmental electromagnetic noise being within the target range and the intensity of the environmental electromagnetic noise being greater than a set threshold, wherein the target range is a preset range centered on the frequency of the signal emitted by the electromagnetic pen; or, the preset conditions include the frequency of the environmental electromagnetic noise being within the target range, and the intensity of the environmental electromagnetic noise being greater than a set threshold, the duration being greater than a set duration, and the environmental electromagnetic noise being narrowband noise.
10. The sensing device according to claim 8, characterized in that, The frequency switching signal sent to the electromagnetic pen includes: sending the frequency switching signal to the electromagnetic pen during a specific time window within one working cycle of the electromagnetic pen.
11. The sensing device according to claim 8, characterized in that, The resonant circuit of the electromagnetic pen includes a resonant coil and a variable capacitor unit. The second control unit is also configured to: The resonant frequency of the resonant circuit is determined based on the frequency band of the ambient electromagnetic noise, the capacitance value of the variable capacitor unit in the resonant circuit is determined based on the adjusted resonant frequency, and the frequency switching signal is generated based on the capacitance value.
12. The sensing device according to claim 11, characterized in that, When the variable capacitor unit is a digital capacitor array, generating the frequency switching signal based on the capacitance value includes: The capacitance combination method of the digital capacitor array is determined based on the capacitance value, and the capacitance combination method is used to indicate the capacitors in the digital capacitor array that are electrically connected to the resonant coil. The frequency switching signal is generated according to the capacitor combination method.
13. The sensing device according to claim 11, characterized in that, When the variable capacitor unit includes a varactor diode and a digital-to-analog converter, generating the frequency switching signal based on the capacitance value includes: Based on the capacitance value, determine the voltage signal to be applied across the varactor diode; The voltage signal is converted into digital signal form of capacitor control information; The frequency switching signal is generated based on the capacitor control information.
14. A display device, characterized in that, The display device includes the sensing device according to any one of claims 8 to 13.
15. An electromagnetic pen system, characterized in that, The system includes the electromagnetic pen according to any one of claims 1 to 7, and the sensing device according to any one of claims 8 to 13; Alternatively, the system may include the electromagnetic pen of any one of claims 1 to 7, and the display device of claim 14.