Anti-interference circuit and capacitive pen

Abstract

This invention discloses an active anti-interference circuit for a capacitive pen and the pen itself. The anti-interference circuit includes a receiving electrode, a main control circuit, and an inverting amplifier circuit. The receiving electrode is disposed on the pen body and receives the uplink signal output from the touchscreen. The input terminal of the inverting amplifier circuit is electrically connected to the receiving electrode, and the controlled terminal of the inverting amplifier circuit is electrically connected to the main control circuit. The receiving electrode is also used to output a drive signal to the inverting amplifier circuit and a feedback signal to the main control circuit when the received uplink signal is lower than a preset threshold. When the main control circuit receives the feedback signal, it outputs a control signal to the inverting amplifier circuit. The inverting amplifier circuit amplifies the drive signal according to a preset amplification factor based on the control signal and outputs a corresponding compensation signal to ensure that the uplink signal received by the receiving electrode is higher than the preset threshold. This invention aims to improve the problem of interference caused by the human body to the signal received by the capacitive pen, thereby improving the signal reception performance of the capacitive pen.

Description

Technical Field

[0001] This invention relates to the field of capacitive pen technology, and in particular to an anti-interference circuit and a capacitive pen. Background Technology

[0002] The use of active capacitive styluses in conjunction with capacitive touchscreens is becoming increasingly widespread. In this setup, the touchscreen periodically sends an uplink signal to the active capacitive stylus. The stylus receives and analyzes this uplink signal before asynchronously sending a downlink coding signal back to the screen. However, when a user writes on the touchscreen with the active capacitive stylus, parts of the user's body, such as the palm or arm, easily touch the screen. Due to the human body's conductive properties, the uplink signal sent by the touchscreen is received not only by the active capacitive stylus but also by the user's body parts in contact with the screen. This signal is then transmitted to the active capacitive stylus's reference ground, interfering with the signal received by the stylus and preventing it from properly receiving the uplink signal output from the touchscreen. Summary of the Invention

[0003] The main objective of this invention is to provide an anti-interference circuit and a capacitive pen, which aims to improve the problem of interference caused by the human body to the signal received by the capacitive pen, thereby improving the signal reception performance of the capacitive pen.

[0004] To achieve the above objectives, this invention proposes an anti-interference circuit for use with a capacitive pen, wherein the capacitive pen is used in conjunction with a touchscreen, the capacitive pen includes a pen body, and the anti-interference circuit includes:

[0005] A receiving electrode is disposed on the body of the capacitive pen and is used to receive the uplink signal output by the touch screen.

[0006] The main control circuit is electrically connected to the receiving electrode;

[0007] An inverting amplifier circuit, wherein the input terminal of the inverting amplifier circuit is electrically connected to the receiving electrode, and the controlled terminal of the inverting amplifier circuit is electrically connected to the main control circuit;

[0008] The receiving electrode is also used to output a drive signal to the inverting amplifier circuit and output a corresponding feedback signal to the main control circuit when the received uplink signal is lower than a preset threshold.

[0009] The main control circuit is used to output a corresponding control signal to the inverting amplifier circuit when it receives the feedback signal.

[0010] The inverting amplifier circuit is used to receive the driving signal and the control signal, and to perform inverting amplification of the driving signal according to the control signal by a preset amplification factor and then output a corresponding compensation signal so that the uplink signal received by the receiving electrode is higher than the preset threshold.

[0011] Optionally, the anti-interference circuit further includes:

[0012] An amplitude processing circuit is provided, wherein the controlled terminal of the amplitude processing circuit is electrically connected to the main control circuit, the amplitude processing circuit is electrically connected to the input terminal of the inverting amplifier circuit, and is used to output an amplitude adjustment signal to the inverting amplifier circuit under the control of the main control circuit to adjust the preset amplification factor.

[0013] The inverting amplifier circuit is also used to receive the amplitude adjustment signal, and after performing inverting amplification processing according to the amplitude adjustment signal and the corresponding adjusted preset amplification factor, output a corresponding compensation signal so that the uplink signal received by the receiving electrode is higher than the preset threshold.

[0014] Optionally, the anti-interference circuit includes:

[0015] A filtering circuit is electrically connected to the receiving electrode and is used to filter the driving signal output by the receiving electrode and output a corresponding first electrical signal.

[0016] Optionally, the anti-interference circuit includes:

[0017] An amplifier circuit is electrically connected to the filter circuit and is used to receive the first electrical signal, amplify the first electrical signal, and output a corresponding second electrical signal to the inverting amplifier circuit, so that the inverting amplifier circuit amplifies the second electrical signal in reverse and outputs a corresponding compensation signal.

[0018] Optionally, the inverting amplifier circuit is a transistor inverting amplifier circuit, wherein the transistor inverting amplifier circuit includes a positive input terminal, a negative input terminal, a controlled terminal, and an output terminal, and the transistor inverting amplifier circuit includes:

[0019] A first transistor and a second transistor, wherein the emitter of the first transistor is electrically connected to the negative input terminal, and the emitter of the second transistor is electrically connected to the positive input terminal; the bases of the first transistor and the second transistor are the controlled terminals of the transistor inverting amplifier circuit; and the collector of the second transistor is the output terminal of the transistor inverting amplifier circuit.

[0020] Optionally, the anti-interference circuit includes:

[0021] An inertial measurement unit is electrically connected to the main control circuit and is used to acquire the attitude information of the capacitive pen and generate a corresponding angle signal to the main control circuit, so that the main control circuit controls the amplitude processing circuit to output a corresponding amplitude adjustment signal according to the received angle signal.

[0022] Optionally, the anti-interference circuit includes:

[0023] A pressure measurement unit is electrically connected to the main control circuit and is used to detect the pressure at a preset detection point and output a corresponding pressure detection signal to the main control circuit, so that the main control circuit controls the amplitude processing circuit to output a corresponding amplitude adjustment signal according to the received pressure detection signal.

[0024] Optionally, the anti-interference circuit includes:

[0025] A prompting component, which is electrically connected to the main control circuit;

[0026] The main control circuit is used to control the prompting component to work when the angle signal exceeds the preset standard angle range and / or the pressure detection signal exceeds the preset pen grip force.

[0027] The present invention also proposes a capacitive pen, wherein the capacitive pen includes the anti-interference circuit described in any of the above claims.

[0028] This invention proposes an anti-interference circuit for use with a capacitive stylus. The stylus is used in conjunction with a touchscreen. The stylus includes a stylus body, and the anti-interference circuit includes a receiving electrode, a main control circuit, and an inverting amplifier circuit. The receiving electrode is disposed on the stylus body and is used to receive the uplink signal output by the touchscreen. The input terminal of the inverting amplifier circuit is electrically connected to the receiving electrode, and the controlled terminal of the inverting amplifier circuit is electrically connected to the main control circuit. The receiving electrode is also used to output a drive signal to the inverting amplifier circuit and a corresponding feedback signal to the main control circuit when the received uplink signal is lower than a preset threshold. When the main control circuit receives the feedback signal, it outputs a corresponding control signal to the inverting amplifier circuit. The inverting amplifier circuit receives the drive signal and the control signal, and performs inverting amplification of the drive signal according to a preset amplification factor based on the control signal, and then outputs a corresponding compensation signal so that the uplink signal received by the receiving electrode is higher than the preset threshold.

[0029] In practical applications, when a user writes on a touchscreen using a capacitive stylus, the uplink signal sent by the touchscreen is received by the user's body part touching the touchscreen and transmitted to the reference ground terminal of the capacitive stylus. This interferes with the uplink signal received by the receiving electrode of the capacitive stylus, partially canceling out the uplink signal received by the capacitive stylus. At this time, the uplink signal received by the receiving electrode is lower than a preset threshold, and a corresponding drive signal is output to the inverting amplifier circuit. The inverting amplifier circuit amplifies the drive signal in reverse and outputs a corresponding compensation signal. The compensation signal is opposite to and equal to the interference signal transmitted from the user's body part touching the touchscreen to the reference ground terminal of the capacitive stylus. This ensures that the interference signal transmitted from the user's body part touching the touchscreen to the reference ground terminal will not interfere with the uplink signal received by the capacitive stylus, improving the reliability of the anti-interference circuit of this invention, and thus improving the anti-interference performance and signal reception performance of the capacitive stylus. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of a circuit module of an embodiment of the anti-interference circuit of the present invention;

[0032] Figure 2 This is a schematic diagram of a circuit module of another embodiment of the anti-interference circuit of the present invention;

[0033] Figure 3 This is a schematic diagram of a circuit module of another embodiment of the anti-interference circuit of the present invention;

[0034] Figure 4 This is a schematic diagram of a circuit module of another embodiment of the anti-interference circuit of the present invention;

[0035] Figure 5 This is a schematic diagram of a circuit module of another embodiment of the anti-interference circuit of the present invention;

[0036] Figure 6 This is a specific circuit diagram of an embodiment of the inverting amplifier circuit in the anti-interference circuit of the present invention.

[0037] Explanation of icon numbers:

[0038] label name label name 10 Receiving electrode 20 Main control circuit 30 Inverting amplifier circuit 40 Amplitude processing circuit 50 Filtering circuit 60 Amplifier circuit 70 Inertial Measurement Unit 80 Pressure measurement unit

[0039] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0042] The use of active capacitive styluses in conjunction with capacitive touchscreens is becoming increasingly widespread. In this setup, the touchscreen periodically sends an uplink signal to the active capacitive stylus. The stylus receives and analyzes this uplink signal before asynchronously sending a downlink coding signal back to the screen. However, when a user writes on the touchscreen with the active capacitive stylus, parts of the user's body, such as the palm or arm, easily touch the screen. Due to the human body's conductive properties, the uplink signal sent by the touchscreen is received not only by the active capacitive stylus but also by the user's body parts in contact with the screen. This signal is then transmitted to the active capacitive stylus's reference ground, interfering with the signal received by the stylus and preventing it from properly receiving the uplink signal output from the touchscreen.

[0043] Therefore, refer to Figure 1 This invention proposes an anti-interference circuit for use with a capacitive pen, which is used in conjunction with a touchscreen. The capacitive pen includes a pen body, and the anti-interference circuit includes:

[0044] A receiving electrode 10 is disposed on the capacitive pen body and is used to receive the uplink signal output by the touch screen.

[0045] Main control circuit 20, which is electrically connected to the receiving electrode 10;

[0046] An inverting amplifier circuit 30 is provided, the input terminal of which is electrically connected to the receiving electrode 10, and the controlled terminal of which is electrically connected to the main control circuit 20.

[0047] The receiving electrode 10 is also used to output a driving signal to the inverting amplifier circuit 30 and output a corresponding feedback signal to the main control circuit 20 when the received uplink signal is lower than a preset threshold.

[0048] The main control circuit 20 is used to output a corresponding control signal to the inverting amplifier circuit 30 when it receives the feedback signal;

[0049] The inverting amplifier circuit 30 is used to receive the driving signal and the control signal, and to perform inverting amplification of the driving signal according to the control signal by a preset amplification factor and then output a corresponding compensation signal so that the uplink signal received by the receiving electrode 10 is higher than the preset threshold.

[0050] In this embodiment, the receiving electrode 10 can be made of a conductive medium with conductivity such as metal, insulating material, or semiconductor material. The main control circuit 20 can be implemented using a main controller, such as an MCU, DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), PLC, or SOC (System on Chip). The inverting amplifier circuit 30 can be implemented using a switching transistor inverting amplifier circuit, an operational amplifier inverting circuit, or the main controller.

[0051] Specifically, refer to Figure 2When a user writes on the touchscreen using a capacitive stylus, the touchscreen periodically outputs an uplink signal. The anti-interference circuit of this invention receives the uplink signal from the touchscreen via the capacitive stylus receiving electrode 10. When the uplink signal received by the capacitive stylus circuit is lower than a preset threshold, it indicates that a portion of the uplink signal received by the receiving electrode 10 is canceled out by the human body coupling signal transmitted from the part of the user in contact with the touchscreen to the reference ground terminal. At this time, the receiving electrode 10 outputs a drive signal to the inverting amplifier circuit 30 and a feedback signal to the main control circuit 20. When the control circuit 20 receives the feedback signal from the receiving electrode 10, it outputs a corresponding control signal to the inverting amplifier circuit 30. This causes the inverting amplifier circuit 30 to amplify the driving signal according to a preset amplification factor and output a corresponding compensation signal to the reference ground terminal. This compensation signal cancels out the human body coupling signal at the reference ground terminal, ensuring that the uplink signal received by the capacitive pen circuit via the receiving electrode 10 is the same as the uplink signal output from the touchscreen. The uplink signal from the touchscreen is then processed to complete downlink coding and point reporting operations, thus enabling the capacitive pen to function normally. The preset threshold is set in advance by the R&D personnel. The compensation signal and the human body coupling signal are equal in magnitude but opposite in direction.

[0052] It is important to understand that the frequency of the drive signal output by the receiving electrode 10, i.e. the drive signal received by the inverting amplifier circuit 30, is equal to the frequency of the uplink signal received by the receiving electrode 10 from the touch screen, so as to ensure that the compensation signal output by the inverting amplifier circuit 30 cancels out the human body coupling signal transmitted from the part of the user in contact with the touch screen to the reference ground terminal.

[0053] With the above configuration, the inverting amplifier circuit 30 can output a compensation signal with a phase opposite to the uplink signal to the reference ground terminal to cancel the human body coupling signal, thereby canceling the interference effect of the uplink signal coupled to the part of the user in contact with the touch screen on the active capacitive pen, thus improving the anti-interference performance and signal reception performance of the capacitive pen.

[0054] This invention proposes an anti-interference circuit for use with a capacitive pen. The capacitive pen is used in conjunction with a touchscreen. The capacitive pen includes a pen body, and the anti-interference circuit includes a receiving electrode 10, a main control circuit 20, and an inverting amplifier circuit 30. The receiving electrode 10 is disposed on the pen body and is used to receive the uplink signal output by the touchscreen. The input terminal of the inverting amplifier circuit 30 is electrically connected to the receiving electrode 10, and the controlled terminal of the inverting amplifier circuit 30 is electrically connected to the main control circuit 20. The receiving electrode 10 is also used to output a drive signal to the inverting amplifier circuit 30 and output a corresponding feedback signal to the main control circuit 20 when the received uplink signal is lower than a preset threshold. When the main control circuit 20 receives the feedback signal, it outputs a corresponding control signal to the inverting amplifier circuit 30. The inverting amplifier circuit 30 is used to receive the drive signal and the control signal, and after inverting the drive signal according to a preset amplification factor based on the control signal, outputs a corresponding compensation signal so that the uplink signal received by the receiving electrode 10 is higher than the preset threshold.

[0055] In practical applications, when a user writes on a touchscreen using a capacitive stylus, the uplink signal sent by the touchscreen is received by the user's body part touching the touchscreen and transmitted to the reference ground terminal of the capacitive stylus. This interferes with the uplink signal received by the receiving electrode 10 of the capacitive stylus, partially canceling out the uplink signal received by the capacitive stylus. At this time, the uplink signal received by the receiving electrode 10 is lower than a preset threshold, and a corresponding drive signal is output to the inverting amplifier circuit 30. The inverting amplifier circuit 30 performs inverting amplification of the drive signal and outputs a corresponding compensation signal. The compensation signal is opposite to and equal to the interference signal transmitted from the user's body part touching the touchscreen to the reference ground terminal of the capacitive stylus, ensuring that the interference signal transmitted from the user's body part touching the touchscreen to the reference ground terminal does not interfere with the uplink signal received by the capacitive stylus. This improves the reliability of the anti-interference circuit of the present invention, thereby improving the anti-interference performance and signal reception performance of the capacitive stylus.

[0056] It is understandable that the contact points between different users and the touchscreen vary. To accommodate different users and counteract interference from the human body coupling signal output to the reference ground terminal of the capacitive stylus circuit when the user contacts the touchscreen, in another embodiment of the invention, a reference... Figure 3 The anti-interference circuit further includes:

[0057] An amplitude processing circuit 40 is provided, wherein the controlled terminal of the amplitude processing circuit 40 is electrically connected to the main control circuit 20, and the amplitude processing circuit 40 is electrically connected to the input terminal of the inverting amplifier circuit 30. Under the control of the main control circuit 20, the amplitude processing circuit 40 outputs an amplitude adjustment signal to the inverting amplifier circuit 30 to adjust the preset amplification factor.

[0058] The inverting amplifier circuit 30 is also used to receive the amplitude adjustment signal, and after performing inverting amplification processing according to the amplitude adjustment signal and the corresponding preset amplification factor, output a corresponding compensation signal so that the uplink signal received by the receiving electrode 10 is higher than the preset threshold.

[0059] In this embodiment, the amplitude processing circuit 40 can be implemented using a voltage conversion circuit, such as a step-up / step-down circuit composed of at least one switching transistor, an inductor, and a capacitor, or a voltage conversion chip.

[0060] Specifically, when a user writes on the touchscreen using a capacitive stylus, if the part of the user that is in contact with the touchscreen outputs a human body coupling signal to the reference power supply terminal, that is, when the received uplink signal is lower than a preset threshold, the receiving electrode 10 outputs a feedback signal to the main control circuit 20 and outputs a drive signal to the inverting amplifier circuit 30. The main control circuit 20 determines the strength of the currently received uplink signal based on the feedback signal and outputs a corresponding control signal to the amplitude processing circuit 40, so that the amplitude processing circuit 40 outputs a corresponding amplitude adjustment signal to the inverting amplifier circuit 30 under the control of the main control circuit 20, changing the preset amplification factor of the inverting amplifier circuit 30. The inverting amplifier circuit 30 performs inverting amplification processing according to the adjusted preset amplification factor and outputs a compensation signal to the reference ground terminal, thereby canceling the human body coupling signal and reducing the interference of the human body coupling signal on the capacitive stylus.

[0061] It should be noted that when the received uplink signal is weak, it indicates that the human body coupling signal is strong, canceling out most of the uplink signal received by the receiving electrode 10, resulting in significant interference to the capacitive pen circuit. In this case, the main control circuit 20 will control the amplitude processing circuit 40 to output a stronger amplitude adjustment signal, significantly increasing the amplification factor of the inverting amplifier circuit 30. This causes the inverting amplifier circuit 30 to output a stronger compensation signal, thus counteracting the interference of the human body coupling signal on the capacitive pen. Similarly, when the received uplink signal is strong, it indicates that the human body coupling signal is weak, resulting in less interference to the capacitive pen. In this case, the main control circuit 20 will correspondingly control the amplitude processing circuit 40 to output a weaker amplitude adjustment signal, slightly increasing or decreasing the preset amplification factor of the inverting amplifier, amplifying the drive signal with a smaller amplification factor, thereby counteracting the interference of the human body coupling signal on the reference ground.

[0062] The amplitude processing circuit 40 enables the anti-interference circuit of the present invention to adjust accordingly based on the interference of different users to the capacitive pen, so as to cancel the human body coupling signal transmitted from the user's contact part with the touch screen to the reference ground terminal of the capacitive pen circuit. In this way, the anti-interference performance and signal reception performance of the capacitive pen are further improved.

[0063] In one embodiment of the present invention, reference is made to... Figure 6 The inverting amplifier circuit 30 is a transistor inverting amplifier circuit 30, wherein the transistor inverting amplifier circuit 30 includes a positive input terminal, a negative input terminal, a controlled terminal, and an output terminal, and the transistor inverting amplifier circuit 30 includes:

[0064] A first transistor and a second transistor, wherein the emitter of the first transistor is electrically connected to the negative input terminal, and the emitter of the second transistor is electrically connected to the positive input terminal, the bases of the first transistor and the second transistor are the controlled terminals of the transistor inverting amplifier circuit 30, and the collector of the second transistor is the output terminal of the transistor inverting amplifier circuit 30.

[0065] Specifically, U1 is an inverting amplifier circuit 30 composed of the first transistor K1 and the second transistor K2. GPIO is the input terminal of the inverting amplifier circuit 30, used to receive the drive signal. A is the output terminal of the inverting amplifier circuit 30. Diode D1 is an electrostatic protection circuit. Resistors and capacitors are peripheral circuits of the inverting amplifier circuit 30. The resistors limit current to prevent excessive load from increasing power loss, and the capacitors filter out DC shunts in the drive signal to prevent interference from external signals. V+ and V- are the positive and negative input terminals of the inverting amplifier circuit 30, respectively, used to receive the amplitude adjustment signal output by the amplitude processing circuit 40 described in the above embodiment, thereby changing the amplification factor of U1 and thus changing the strength of the compensation signal output by the inverting amplifier circuit 30.

[0066] The use of resistors and capacitors in the peripheral circuit increases the anti-interference capability of the reverse amplifier circuit 30, and the reverse connection protection circuit increases the reliability of the reverse amplifier circuit 30. At the same time, using transistors as amplification devices is inexpensive and reduces the design cost of the anti-interference circuit of this invention.

[0067] It should be noted that since the receiving electrode 10 of the capacitive pen is generally partially exposed on the outer surface of the pen body to make contact with the touch screen, the receiving electrode 10 of the capacitive pen can easily receive external signals other than the uplink signal output by the touch screen, thereby interfering with the internal circuitry of the capacitive pen.

[0068] Therefore, in one embodiment of the present invention, reference is made to Figure 4 ,

[0069] The anti-interference circuit includes:

[0070] The filter circuit 50 is electrically connected to the receiving electrode 10 and is used to filter the driving signal output by the receiving electrode 10 and output a corresponding first electrical signal.

[0071] The anti-interference circuit includes:

[0072] An amplifier circuit 60 is electrically connected to the filter circuit 50 and is used to receive the first electrical signal, amplify the first electrical signal, and output a corresponding second electrical signal to the inverting amplifier circuit 30, so that the inverting amplifier circuit 30 amplifies the second electrical signal in reverse and outputs a corresponding compensation signal.

[0073] In this embodiment, the filter circuit 50 can be implemented using a filter circuit 50 composed of capacitors and inductors or a filter chip, and the amplifier circuit 60 can be implemented using amplifier devices such as transistors and comparators or amplifier chips.

[0074] Understandably, the filter circuit 50 and the amplifier circuit 60 can be integrated into the same integrated chip to reduce wiring area.

[0075] Specifically, when the receiving electrode 10 of the capacitive stylus receives the uplink signal output from the touchscreen, if the part of the user in contact with the touchscreen interferes with the stylus, meaning the signal actually processed by the stylus circuit is the uplink signal output from the touchscreen canceled out by the human body coupling signal, and the uplink signal received by the receiving electrode 10 is lower than a preset threshold, the received uplink signal will be filtered by the filtering circuit 50 to remove external signal noise, and then amplified by the amplification circuit 60 before outputting a feedback signal to the main control circuit 20. This allows the main control circuit 20 to output a control signal based on the feedback signal to control the inverting amplification circuit 30 to operate. The inverting amplification circuit 30 amplifies the signal according to a preset amplification factor and outputs a corresponding compensation signal to cancel out the interference of the human body coupling signal on the reference ground. In conjunction with the above embodiment, the main control circuit 20 can determine the strength of the human body coupling signal based on the feedback signal, and then control the amplitude processing circuit 40 to output an amplitude adjustment signal to change the amplification factor of the inverting amplification circuit 30, so as to output a compensation signal that is equal in magnitude but opposite in direction to the human body coupling signal.

[0076] The above settings ensure that the signals received by the main control circuit 20 and the inverting amplifier circuit 30 are more accurate, thereby increasing the accuracy of the main control circuit 20 and the accuracy of the compensation signal output by the inverting amplifier circuit 30.

[0077] It is understandable that different ways of holding the pen will result in different human body coupling signals transmitted from the part of the user in contact with the touch screen to the reference ground terminal of the capacitive pen circuit, that is, the degree of interference to the capacitive pen will be different.

[0078] Therefore, in another embodiment of the invention, reference is made to Figure 5 The anti-interference circuit includes:

[0079] An inertial measurement unit 70 is electrically connected to the main control circuit 20 and is used to acquire the attitude information of the capacitive pen and generate a corresponding angle signal to the main control circuit 20, so that the main control circuit 20 controls the amplitude processing circuit 40 to output a corresponding amplitude adjustment signal according to the received angle signal.

[0080] In this embodiment, the inertial measurement unit 70 can be implemented using an inertial sensor or the main controller described in the above embodiments.

[0081] Specifically, different pen grips result in different tilt angles for the capacitive pen. When a user writes on the touchscreen with the capacitive pen, the inertial measurement unit 70 acquires the pen's posture information to determine its tilt angle and generates a corresponding angle signal to the main control circuit 20. The main control circuit 20 determines the pen's tilt angle based on the angle signal, processes it according to a preset control algorithm, and outputs a corresponding control signal. This control signals the amplitude processing circuit 40 to output a corresponding amplitude adjustment signal, causing the inverting amplifier circuit 30 to amplify the received drive signal according to the amplification factor corresponding to the amplitude adjustment signal, and output a compensation signal to the reference ground. The preset control algorithm is pre-set by the developers. Thus, the anti-interference circuit of this invention can control the magnitude of the compensation signal according to the pen's tilt angle, improving the accuracy of the compensation signal, thereby improving the accuracy of the anti-interference circuit and the signal reception performance of the capacitive pen.

[0082] Alternatively, in another embodiment of the invention, reference is made to... Figure 5 The anti-interference circuit includes:

[0083] The pressure measurement unit 80 is electrically connected to the main control circuit 20 and is used to detect the pressure at a preset detection point and output a corresponding pressure detection signal to the main control circuit 20, so that the main control circuit 20 controls the amplitude processing circuit 40 to output a corresponding amplitude adjustment signal according to the received pressure detection signal.

[0084] In this embodiment, the pressure measurement unit 80 can be implemented using a piezoresistive pressure sensor, a strain gauge pressure sensor, a capacitive pressure sensor, etc.

[0085] Specifically, multiple preset detection points can be set on the outer surface of the capacitive pen. For example, the first preset detection point is set at the pressure point on the pad of the thumb when holding the pen; the second preset detection point is set at the pressure point on the pad of the index finger when holding the pen; the third preset detection point is set at the pressure point on the side of the middle finger when holding the pen; and the fourth preset detection point is set at the pressure point on the side of the base of the index finger when holding the pen. These preset detection points can be marked on the outer surface of the capacitive pen to encourage users to position their hands according to these markings. The specific locations of the preset detection points can be pre-set by the developers to suit the pen-holding habits of most users. The pressure measurement unit 80 is electrically connected to preset detection points. When the pressure measurement unit 80 is subjected to external pressure applied to each preset detection point, such as the pressure when a user holds a pen to write on a touchscreen, it outputs a corresponding pressure detection signal to the main control circuit 20. The main control circuit 20 then controls the amplitude processing circuit 40 to output a corresponding amplitude adjustment signal based on the pressure detection signal. This, in turn, causes the inverting amplifier circuit 30 to amplify the drive signal in reverse according to the amplification factor corresponding to the amplitude adjustment signal and output a compensation signal to the reference ground terminal. Thus, the main control circuit 20 can calculate and process the pen grip force according to a preset control algorithm and output a corresponding control signal to control the amplitude processing circuit 40 to output the corresponding amplitude adjustment signal. The preset control algorithm is pre-set by the developers. This invention's anti-interference circuit can control the magnitude of the compensation signal according to the user's pen grip force, improving the accuracy of the compensation signal, thereby improving the accuracy of the anti-interference circuit and the signal reception performance of the capacitive pen.

[0086] It is understandable that the pressure measurement unit 80, the inertial measurement unit 70 and the main control circuit 20 can be any two or three of them combined and integrated into the same integrated chip to reduce the wiring area.

[0087] In conjunction with the above embodiments, in one embodiment of the present invention, the anti-interference circuit includes:

[0088] The prompting component is electrically connected to the main control circuit 20;

[0089] The main control circuit 20 is used to control the prompting component to work when the angle signal exceeds the preset standard angle range and / or the pressure detection signal exceeds the preset pen grip force.

[0090] In this embodiment, the prompting component can be implemented using an audio prompting component or an optical prompting component. The audio prompting component can be a speaker, a buzzer, or the like; the optical prompting component can be an indicator light, or the like.

[0091] Taking the indicator light as an example, when the main control circuit 20 receives the angle signal output by the inertial measurement unit 70, it judges the angle signal. If the angle signal exceeds the preset standard angle range, it controls the indicator light to activate, prompting the user to change the pen grip to adjust the tilt angle of the capacitive pen. Alternatively, when the main control circuit 20 receives the pressure detection signal output by the pressure measurement unit 80, it judges whether the pressure detection signal exceeds the preset pen grip force. If it does, it controls the indicator light to activate, prompting the user to adjust the pen grip force. The preset standard angle range and preset pen grip force are set in advance by the R&D personnel. For example, the human body coupling signal strength transmitted from the user's contact point with the touchscreen to the reference ground is lowest when the preset standard angle range or preset pen grip force is applied, minimizing interference with the capacitive pen. In some cases, the human body coupling signal value even drops to zero within the preset standard angle range and preset pen grip force. In this way, not only can the compensation signal output by the inverting amplifier circuit 30 cancel out the interference of human body coupling signal, but the prompting component can also prompt the user to change the way and pressure of holding the pen, thereby reducing the interference of human body coupling signal and improving the signal reception performance of the capacitive pen.

[0092] The present invention also proposes a capacitive pen, wherein the capacitive pen includes the anti-interference circuit described in any of the above claims.

[0093] It is worth noting that since the capacitive pen of the present invention is based on the above-mentioned anti-interference circuit, the embodiments of the capacitive pen of the present invention include all the technical solutions of all embodiments of the above-mentioned anti-interference circuit, and the technical effects achieved are exactly the same, which will not be repeated here.

[0094] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An anti-interference circuit applied to a capacitive pen, the capacitive pen being used in conjunction with a touchscreen, the capacitive pen comprising a pen body, characterized in that... The anti-interference circuit includes: A receiving electrode is disposed on the body of the capacitive pen and is used to receive the uplink signal output by the touch screen. The main control circuit is electrically connected to the receiving electrode; An inverting amplifier circuit, wherein the input terminal of the inverting amplifier circuit is electrically connected to the receiving electrode, and the controlled terminal of the inverting amplifier circuit is electrically connected to the main control circuit; and An amplitude processing circuit is provided, wherein the controlled terminal of the amplitude processing circuit is electrically connected to the main control circuit, the amplitude processing circuit is electrically connected to the input terminal of the inverting amplifier circuit, and is used to output an amplitude adjustment signal to the inverting amplifier circuit under the control of the main control circuit to adjust the preset amplification factor. The receiving electrode is also used to output a drive signal to the inverting amplifier circuit and output a corresponding feedback signal to the main control circuit when the received uplink signal is lower than a preset threshold. The main control circuit is used to output a corresponding control signal to the inverting amplifier circuit when it receives the feedback signal. The reverse amplifier circuit is used to receive the drive signal and the control signal, and after performing reverse amplification processing on the drive signal according to the control signal by a preset amplification factor, output a corresponding compensation signal so that the uplink signal received by the receiving electrode is higher than the preset threshold. The inverting amplifier circuit is also used to receive the amplitude adjustment signal, and after performing inverting amplification processing according to the amplitude adjustment signal and the corresponding adjusted preset amplification factor, output a corresponding compensation signal so that the uplink signal received by the receiving electrode is higher than the preset threshold.

2. The anti-interference circuit as described in claim 1, characterized in that, The anti-interference circuit includes: A filtering circuit is electrically connected to the receiving electrode and is used to filter the driving signal output by the receiving electrode and output a corresponding first electrical signal.

3. The anti-interference circuit as described in claim 2, characterized in that, The anti-interference circuit includes: An amplifier circuit is electrically connected to the filter circuit and is used to receive the first electrical signal, amplify the first electrical signal, and output a corresponding second electrical signal to the inverting amplifier circuit, so that the inverting amplifier circuit amplifies the second electrical signal in reverse and outputs a corresponding compensation signal.

4. The anti-interference circuit as described in claim 1, characterized in that, The inverting amplifier circuit is a transistor inverting amplifier circuit, wherein the transistor inverting amplifier circuit includes a positive input terminal, a negative input terminal, a controlled terminal, and an output terminal, and the transistor inverting amplifier circuit includes: A first transistor and a second transistor, wherein the emitter of the first transistor is electrically connected to the negative input terminal, and the emitter of the second transistor is electrically connected to the positive input terminal; the bases of the first transistor and the second transistor are the controlled terminals of the transistor inverting amplifier circuit; and the collector of the second transistor is the output terminal of the transistor inverting amplifier circuit.

5. The anti-interference circuit as described in claim 1, characterized in that, The anti-interference circuit includes: An inertial measurement unit is electrically connected to the main control circuit and is used to acquire the attitude information of the capacitive pen and generate a corresponding angle signal to the main control circuit, so that the main control circuit controls the amplitude processing circuit to output a corresponding amplitude adjustment signal according to the received angle signal.

6. The anti-interference circuit as described in claim 1, characterized in that, The anti-interference circuit includes: A pressure measurement unit is electrically connected to the main control circuit and is used to detect the pressure at a preset detection point and output a corresponding pressure detection signal to the main control circuit, so that the main control circuit controls the amplitude processing circuit to output a corresponding amplitude adjustment signal according to the received pressure detection signal.

7. The anti-interference circuit as described in any one of claims 1-6, characterized in that, The anti-interference circuit includes: A prompting component, which is electrically connected to the main control circuit; The main control circuit is used to control the prompting component to work when the angle signal exceeds the preset standard angle range and / or the pressure detection signal exceeds the preset pen grip force.

8. A capacitive pen, characterized in that, The capacitive pen includes an anti-interference circuit as described in any one of claims 1-7.

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