Position sensing device

Abstract

The utility model belongs to the technical field of touch control circuits, in particular to a position sensing device, which is characterized in that a first output voltage signal corresponding to a first sensing signal generated by a first capacitor formed between a first group of electrodes and a second group of electrodes is input into a voltage judgment circuit; the voltage judgment circuit is provided with a comparison threshold voltage with a settable first level, and outputs a first digital pulse wave signal according to the voltage relation between the comparison threshold voltage with the settable first level and the first output voltage signal. And then, according to the difference between a pulse wave width of the first digital pulse wave signal in a unit time and a default value, whether the object to be detected is close to the position of the capacitor is judged, so that the accuracy of a sensing result can be prevented from being influenced by unstable material characteristics; and the interference is filtered by comparing the first output voltage signal corresponding to the first sensing signal subsequently.

Description

Technical Field

[0001] The utility model belongs to the technical field of touch circuits, and particularly relates to a position sensing device. Background Art

[0002] The capacitive touch panel uses the capacitance effect to realize touch detection. The capacitive touch panel usually consists of a touch surface coated with a conductive material and a sensor electrode behind it. There is also a structure formed by two layers of conductive strips to form a two-layer electrode matrix. When touching the touch panel with a hand, a finger will form a capacitance point, that is, an electric field is formed between the touch surface and the back electrode. The sensor electrode will sense the change of the electric field and convert it into an electrical signal, and based on this, the touch position is judged.

[0003] Regarding the specific technology of the capacitive touch panel, for example, the Chinese patent document with the publication number CN102207807A records a circuit for determining the position of a pressure contact point, a touch panel module, and a method for detecting a pressure contact point. The capacitive sensing panel has a plurality of sensing lines and driving lines. The circuit includes a plurality of first amplifiers and second amplifiers respectively connected to the plurality of sensing lines and driving lines. One input terminal of each first amplifier is connected to a first input signal source, and one input terminal of each second amplifier is selectively connected to the first input signal source or a second input signal source through a switch; when operating in a first operation mode, the input terminal of each second amplifier is coupled to the first input signal source, and when operating in a second operation mode, the input terminals of a plurality of specific second amplifiers among the plurality of second amplifiers are coupled to the second input signal source.

[0004] Another example is that the Chinese patent document with the publication number CN101727253A records a method for sensing the touch position of a touch device. The method drives and scans the first and second conductive layers via a control circuit in a preset scanning sensing mode. When it is sensed that the touch panel is subjected to a touch pressure operation, the type of the touch pressure operation on the touch panel is discriminated: including single-point touch pressure, continuous trajectory input, or multi-point touch pressure, and the first and second conductive layers of the touch panel are driven and scanned in corresponding first or second operation modes to sense the coordinate positions of the touch pressure point or the continuous trajectory input. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model:

[0006] Although capacitive touch technology has been widely applied in various product fields, there are still some challenges and problems. Since traditional capacitive touch technology usually relies on the circuit characteristics of conductive materials, sometimes the instability of these material characteristics may affect the accuracy of sensing results. Moreover, traditional capacitive touch technology is easily affected by external environments, such as humidity, temperature changes, electromagnetic interference, etc. To improve stability and reliability, the sensing circuit needs to take measures to resist these possible interferences.

[0007] The present utility model aims to provide a position sensing device to achieve the adaptability of the position sensing device to different environmental influencing factors during the working state and improve the anti-interference ability.

[0008] The present utility model is a position sensing device applied to the position sensing of a to-be-tested object. The position sensing device includes: a sensing panel, which includes a first group of electrodes and a second group of electrodes. A first capacitor is formed at the proximity of a first electrode in the first group of electrodes and a second electrode in the second group of electrodes; a signal processing circuit, which is electrically connected to the first group of electrodes and the second group of electrodes and includes a voltage amplifier and a voltage judgment circuit. The signal processing circuit is used to emit an alternating drive signal from the first electrode in the first group of electrodes, generate a first induction signal at the second electrode through the first capacitor, send the first induction signal and a reference signal into the voltage amplifier, and then obtain a first output voltage signal. The first output voltage signal is input into the voltage judgment circuit. The voltage judgment circuit has a comparison threshold voltage with a first level that can be set. The voltage judgment circuit outputs a first digital pulse signal (Digital Pulse) according to the voltage magnitude relationship between the comparison threshold voltage with the first level that can be set and the first output voltage signal. According to the difference between the pulse width of the first digital pulse signal within a unit time and a default value, it is further determined whether the to-be-tested object is close to the position where the first capacitor is located.

[0009] According to the above concept, for the position sensing device described in the present utility model, the to-be-tested object is one of a human finger and a capacitive touch pen, and the alternating drive signal is an adjustable digital sine wave signal. By changing the frequency or amplitude of the adjustable digital sine wave signal, the charging voltage and charging time of the capacitor are changed to adjust the waveform of the first induction signal.

[0010] According to the above concept, for the position sensing device of the present utility model, a second capacitor is formed at the proximity between a third electrode adjacent to the second electrode among the second group of electrodes in the sensing panel and the first electrode. The alternating current (AC) drive signal on the first electrode generates a second induction signal on the third electrode through the second capacitor. The second induction signal is used as the reference signal and is sent together with the first induction signal to the voltage amplifier formed by an operational amplifier, thereby obtaining the first output voltage signal.

[0011] According to the above concept, for the position sensing device of the present utility model, the voltage determination circuit includes a first inverter and a second inverter. The first inverter outputs the first digital pulse signal according to the voltage magnitude relationship between the first settable comparison threshold voltage and the first output voltage signal. The second inverter outputs a second digital pulse signal according to the voltage magnitude relationship between the second settable comparison threshold voltage and the first output voltage signal. According to the pulse width change amount of the first digital pulse signal and the second digital pulse signal within the unit time, it is further determined whether the object to be measured is close to the position where the first capacitor is located.

[0012] According to the above concept, the position sensing device of the present utility model further includes an integrator, electrically connected between the voltage amplifier and the voltage determination circuit. The integrator is used to perform an integration process on the first output voltage signal and then send it into the voltage determination circuit.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0014] (1) The position sensing device includes an object to be measured, and between a first group of electrodes and a second group of electrodes. The sensing device first emits an alternating current (AC) drive signal from a first electrode among the first group of electrodes. A first capacitor is formed at the proximity between a second electrode among the second group of electrodes and the first electrode. The alternating current (AC) drive signal on the first electrode generates a first induction signal on the second electrode through the first capacitor. This kind of position sensing device emits a drive signal through the electrodes in the first group of electrodes, and then the touch of a finger or a stylus affects the first induction signal. This way of generating the induction signal does not depend on the circuit characteristics of the conductive material, and can avoid the instability of the material characteristics from affecting the accuracy of the sensing result.

[0015] (2) The first output voltage signal corresponding to the first induction signal generated by the first capacitor formed between the first group of electrodes and the second group of electrodes is input into a voltage judgment circuit. The voltage judgment circuit has a first-level adjustable comparison threshold voltage. The voltage judgment circuit outputs a first digital pulse signal according to the voltage magnitude relationship between the first-level adjustable comparison threshold voltage and the first output voltage signal. Then, according to the difference between the pulse width of the first digital pulse signal within a unit time and a default value, it is further determined whether the object to be measured is close to the position where the capacitor is located. In this way, by subsequently comparing the first output voltage signal corresponding to the first induction signal, interference is filtered out, such as filtering out unstable interference signals caused by humidity, temperature changes, electromagnetic interference, etc. in the external environment, improving the stability and reliability of position sensing, and no other measures need to be taken to resist these possible interferences. Brief Description of the Drawings

[0016] After reading the following detailed description and the drawings, the above content of the present invention will become more obvious to those of ordinary skill in the art. Among them, the drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0017] Figure 1 A functional block diagram of a position sensing device developed according to an embodiment of the present invention is shown;

[0018] Figure 2 A schematic diagram of another position sensing device developed according to an embodiment of the present invention is shown;

[0019] Figure 3 , which is a flowchart of position sensing that can be executed on the mutual capacitance sensing panel and the signal processing circuit in the above Figure 1 ;

[0020] Figure 4 , which is a schematic diagram of the functional block of an embodiment of a part of the circuit in the above signal processing circuit;

[0021] Figure 5 , which is a schematic diagram of a circuit example of the input / output port in the voltage amplifier module of this case;

[0022] Figure 6 , which is a schematic diagram of a circuit example of the operational amplifier in the voltage amplifier module of this case;

[0023] Figure 7 , which is a schematic diagram of a circuit example of the integrator in the voltage amplifier module of this case;

[0024] Figure 8, which is a schematic diagram of the circuit example of the voltage judgment circuit in the voltage amplifier module of this case;

[0025] Figure 9 , which is a schematic diagram of the voltage signal waveform related to this case. Detailed implementation manners

[0026] The present utility model will now be described more specifically in conjunction with the following embodiments. It should be noted that the following description of the preferred embodiments of the present utility model is only for the purpose of illustration and description. It is not intended to be exhaustive or limited to the exact form disclosed. The described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0027] Figure 1 Shows a schematic diagram of a position sensing device developed according to an embodiment of the present utility model, which mainly includes a mutual capacitance sensing panel 11 and a signal processing circuit 12. In this example, the mutual capacitance sensing panel 11 can be completed in a common two-dimensional wiring manner (of course, not limited thereto), and it includes a first group of m electrodes X1, X2... Xm extending in the first direction (vertical direction in this figure) and a second group of n electrodes Y1, Y2... Yn extending in the second direction (horizontal direction in this figure). And the adjacent positions (crossover positions in this example) between the electrodes X1, X2... Xm and the electrodes Y1, Y2... Yn are usually separated by an insulating material (not shown in this figure) to form a capacitor 110. Moreover, between the mutual capacitance sensing panel 11 and the user's finger (or other conductor to be measured such as a capacitive stylus) 14, a protective cover plate (not shown in this figure) is usually provided to separate them.

[0028] As for Figure 2FIG. 0 shows a schematic diagram of another position sensing device developed according to an embodiment of the present invention, which mainly includes a self-capacitive sensing panel 13 and the signal processing circuit 12. In this example, the self-capacitive sensing panel 13 can also be used to complete the setting of multiple electrodes in a common two-dimensional distribution (for example, along the horizontal direction and the vertical direction, of course, not limited to this). A capacitor 132 will be correspondingly formed between a certain electrode 131 and a basic voltage (such as the ground voltage GND on the ground electrode 130, of course, not limited to this design). Moreover, between the self-capacitive sensing panel 13 and the user's finger (or other conductive objects to be measured such as a capacitive stylus) 14, a protective cover plate (not shown in this figure) is usually provided to separate them. The user's finger 14, which also forms another capacitor with the ground voltage GND, will change the electrical property value of the capacitor 132 measured by the signal processing circuit 12 when approaching the electrode 131.

[0029] To clearly understand the technical means of this case, please refer to Figure 3 again, which is a position sensing flowchart that can be executed on the mutual-capacitive sensing panel 11 and the signal processing circuit 12 in the above Figure 1 First, the signal processing circuit 12 can send an alternating current drive signal from one of the first electrodes (any one of X1, X2... Xm) in the first group of electrodes. A capacitor is formed between one of the second electrodes (any one of Y1, Y2... Yn) in the second group of electrodes and the proximity of the first electrode. The alternating current drive signal on the first electrode generates a first induction signal on the second electrode through the capacitor (step 21). The preferred embodiment of the alternating current drive signal is an adjustable digital sine wave signal. The adjustable digital sine wave signal can be generated by hardware such as a digital signal processor (DSP) or a direct digital synthesizer (DDS). By setting parameters related to frequency and amplitude, the frequency and amplitude of the sine wave signal can be adjusted, thereby changing the charging voltage and charging time of the capacitor, so as to achieve the purpose of adjusting the waveform of the first induction signal.

[0030] In addition, the above position sensing flowchart executed on the mutual-capacitive sensing panel 11 and the signal processing circuit 12 can also be applied to the above Figure 2It is executed on the self - capacitive sensing panel 13 and the signal processing circuit 12 in []. First, the signal processing circuit 12 can send an alternating - current drive signal on one of the group of electrodes, i.e., electrode 131. A capacitor 132 is formed between the electrode 131 and the grounded electrode 130 (or other ground points with a basic voltage). The alternating - current drive signal on the first electrode is sent into the capacitor 132 to generate a first induction signal (step 21). A preferred embodiment of the alternating - current drive signal is an adjustable digital sine wave signal. The adjustable digital sine wave signal can be generated by hardware such as a Digital Signal Processor (DSP) or a Direct Digital Synthesizer (DDS). By setting parameters related to frequency and amplitude, the frequency and amplitude of the sine - wave signal can be adjusted, thereby changing the charging voltage and charging time of the capacitor, so as to achieve the purpose of adjusting the waveform of the first induction signal.

[0031] Next, both of the above - mentioned sensing panels can send the first induction signal and a reference signal into a voltage amplifier to obtain a first output voltage signal (step 22). Then, the first output voltage signal is input into a voltage judgment circuit. The voltage judgment circuit has a comparison threshold voltage with an adjustable level. The voltage judgment circuit outputs a digital pulse signal according to the voltage magnitude relationship between the adjustable - level comparison threshold voltage and the first output voltage signal (step 23). Finally, according to the difference between the pulse width of the digital pulse signal within a unit time and a default value, it is further determined whether the object to be measured is close to the position where the capacitor is located (step 24). In this way, with this position - sensing device, in this case, the position sensing of the object to be measured can be completed on both self - capacitive and mutual - capacitive capacitive touch - sensing panels. The above - mentioned voltage judgment circuit and voltage amplifier can both be completed in the signal processing circuit 12.

[0032] In addition, on the premise that the voltage amplitude of the first induction signal is large enough, step 22 can be omitted during the sensing of the device in this case, and the first induction signal can be directly used as the first output voltage signal and directly sent into the voltage judgment circuit. The voltage judgment circuit also has a comparison threshold voltage with a settable level. The voltage judgment circuit can also output a digital pulse signal similar to that in step 23 according to the relationship between the settable comparison threshold voltage and the voltage of the first output voltage signal, and then step 24 is carried out: according to the difference between the pulse width of the digital pulse signal within a unit time and a default value, it is further judged whether the object to be measured is close to the position of the capacitor.

[0033] Please refer to Figure 4 , which is a schematic diagram of the functional blocks of a part of the signal processing circuit 12 above. The signal processing circuit 12 is electrically connected to the first group of electrodes X1, X2... Xm and the second group of electrodes Y1, Y2... Yn in the sensing panel 11. The signal processing circuit 12 includes an AC drive signal generator (not shown in this figure), an input / output signal processing module 121, a voltage amplifier module 122, an integrator module 123, and a voltage judgment circuit module 124. Among them, the AC drive signal generator (not shown in this figure) is used to send an AC drive signal from the first electrode in the first group of electrodes, and through the first capacitor formed at the proximity between one of the second electrodes in the second group of electrodes in the sensing panel 11 and the first electrode, a first induction signal can be generated on the second electrode. The preferred embodiment of the AC drive signal is an adjustable digital sine wave signal, and the AC drive signal generator can be completed by using a digital signal processor (DSP for short) or a direct digital synthesizer (DDS for short). By setting parameters related to frequency and amplitude, the frequency and amplitude of the sine wave signal can be adjusted, and thus the charging voltage and charging time of the first capacitor can be changed to achieve the purpose of adjusting the waveform of the first induction signal.

[0034] Of course, the AC drive signal on the first electrode can also be coupled through the second capacitor formed at the proximity between the first electrode and one of the third electrodes adjacent to the second electrode in the second group of electrodes in the sensing panel 11, and a second induction signal can be generated on the third electrode. Then the second induction signal can be used as the reference signal and compared with the first induction signal through an input / output port 1210 in the input / output signal processing module 121 (for the circuit example, please refer toFigure 5 , in the figure, the switch groups S[1:0] and C[1:0] can respectively select their conduction paths with binary digits. When S[1:0] = 00, the uppermost switch is conducted; when S[1:0] = 01, GND is conducted; when S[1:0] = 10, VCOM is conducted; when S[1:0] = 11, VCC is conducted. When C[1:0] = 01, the switch connecting to VCOM is conducted; when C[1:0] = 10, the switch connecting to GND is conducted, and the other combinations of C[1:0] are not conducted. In this self-capacitance embodiment, S[1:0] mainly selects GND and VCOM or VCC in sequence in terms of timing to generate a driving signal for the electrode connected to SEN, and C[1:0] selects GND to discharge the electrode through a series-connected resistor. Also, if in a mutual-capacitance embodiment, S[1:0] selects to conduct the uppermost switch, and C[1:0] selects VCOM to stably send the DC potential of the electrode through a series-connected resistor) and send it into one of the operational amplifiers 1220 in the voltage amplifier module 122 (for a circuit example, see Figure 6 , in the figure, the switch groups S[3:2], S4, and S5 can respectively select their conduction paths with binary digits. When S5 = 0, the signal amplification function of the voltage amplifier is enabled; when S5 = 1, the signal integration function of the voltage amplifier is enabled; when S5 = 1 and S4 is conducted, the voltage amplifier can be reset. In this self-capacitance embodiment, S[3:2] mainly selects VCOM, and S4 and S5 respectively select to reset the voltage amplifier and enable the signal amplification function or the signal integration function in sequence in terms of timing. Also, if in a mutual-capacitance embodiment, S[3:2] mainly still selects, and S4 and S5 also select to reset the voltage amplifier and enable the signal amplification function or the signal integration function in sequence in terms of timing), and then the first output voltage signal is obtained. For example, if there is no object to be detected approaching or touching the sensing panel 11, the waveforms (such as amplitude, frequency, and phase) of the first induction signal and the second induction signal received by the signal processing circuit 12 are the same or have very little difference, so that the first output voltage signal output by the operational amplifier 1220 is at a first level (such as a low voltage level). However, if an object to be detected (such as a user's finger) is placed at the position of the first capacitor, it will cause a difference in the waveforms (such as amplitude, frequency, and phase) of the above-mentioned first induction signal and the second induction signal, and through the differential amplification function of the operational amplifier 1220, the first output voltage signal output by it is at a second level (such as a high voltage level).

[0035] As for the integrator module 123, it can be composed of a plurality of integrators 1230 (for a circuit example, see Figure 7) is completed by being electrically connected between the voltage amplifier 122 and the voltage judgment circuit 124. The integrator 1230 is used to perform an integration process on the first output voltage signal output by the voltage amplifier 122 to accumulate the energy of the first output voltage signal and generate a first output voltage integration signal, and then send the first output voltage integration signal into the voltage judgment circuit 124 for touch judgment. In addition, through the control of the integrator 1230 by switches g3, g4, g5, S7, S8 and S9, turning on S9 can reset the integrator, and can also adjust the integration timing (Window, which can be controlled by switch S8), integration speed (which can be controlled by switches g3, g4, g5) and integration direction (which can be controlled by switch S7) to enhance its differential amplification performance. Of course, in another embodiment, if the differential energy of the first output voltage signal is large enough, the processing of the integrator module 123 can also be skipped (for example, it can be executed by switch S6 in Figure 4 ) or the design of the integrator module 123 can be cancelled, and directly send the first output voltage signal output by the voltage amplifier 122 into the voltage judgment circuit 1240 for touch judgment. The above-mentioned integration timing (Window) can mainly be coordinated with the effective peak region of the AC drive signal, and the integration speed and the number of integrations can be adjusted according to whether the output voltage integration signal reaches the required potential. For example, if the comparator is required to make different responses when there is touch and when there is no touch, the required potential must cross 1 / 2VCC (VCC is the working voltage inside the comparator) when changing from having touch to not having touch or from not having touch to having touch.

[0036] Regarding the voltage judgment circuit 1240 in the voltage judgment circuit module 124 (for its circuit example, please refer to Figure 8 ) includes a first inverter 12401 and a second inverter 12402. The first inverter 12401 outputs the first digital pulse signal according to the voltage magnitude relationship between the first level-settable comparison threshold voltage (a[3:0]-ADJ, the voltage magnitude can be controlled by four bits) and the voltage of the first output voltage signal (or the first output voltage integration signal) AI. The second inverter 12402 outputs a second digital pulse signal according to the voltage magnitude relationship between a second level-settable comparison threshold voltage (a[7:4]-ADJ, the voltage magnitude can be controlled by four bits) and the voltage of the first output voltage signal (or the first output voltage integration signal). According to the pulse width change amount of the first digital pulse signal and the second digital pulse signal within the unit time (for example, half, one or more AC drive signal cycles), it is further determined whether the object to be measured is located at the position of the first capacitor.

[0037] Please refer toFigure 9 As shown in the figure, it is a schematic diagram of the voltage signal waveform related to this case. Among them, the triangular wave 51 shown by the dotted line represents the AI voltage signal when the touch panel is not touched, and the triangular wave 52 shown by the solid line represents the AI voltage signal when the touch panel is touched. The voltage marked as THD1 in the figure is the optimal value of the first level-settable comparison threshold voltage mentioned above, and the voltage marked as THD4 in the figure is the optimal value of the second level-settable comparison threshold voltage mentioned above. The length represented by the single line segment 53 in the figure is the pulse width of the first digital pulse signal output by the first inverter 12401 according to the voltage magnitude relationship between the optimal value THD1 of the first level-settable comparison threshold voltage and the AI voltage signal when the touch panel is not touched. The length represented by the single line segment 54 in the figure is the pulse width of the second digital pulse signal output by the second inverter 12402 according to the voltage magnitude relationship between the optimal value THD4 of the second level-settable comparison threshold voltage and the AI voltage signal when the touch panel is not touched.

[0038] Compared with the AI voltage signal (the triangular wave 52 shown by the solid line) when the touch panel is touched, the pulse width of the first digital pulse signal output by the first inverter 12401 according to the voltage magnitude relationship between the optimal value THD1 of the first level-settable comparison threshold voltage and the AI voltage signal when the touch panel is touched is reduced to 0. Similarly, the pulse width of the second digital pulse signal output by the second inverter 12402 according to the voltage magnitude relationship between the optimal value THD4 of the second level-settable comparison threshold voltage and the AI voltage signal when the touch panel is touched is also reduced to 0.

[0039] In this way, in this example, the change amount of the pulse width within a unit time (such as half, one, or more alternating drive signal cycles) changes from the sum of the time lengths of the line segments 53 and 54 when the touch panel is not touched to 0 when the touch panel is touched. Then, when the change amount of the pulse width measured on the first capacitor is greater than a preset value, it can be further determined that the touch point of the object to be measured is located at the position of the first capacitor.

[0040] As for the voltage labeled as THD2 in the figure, it is the general value of the first level - settable comparison threshold voltage mentioned above. And the voltage labeled as THD3 in the figure is the general value of the second level - settable comparison threshold voltage mentioned above. In the figure, the sum of the lengths of the two separated line segments 55 and 56 is the change in the pulse width of the first digital pulse signal generated by the first inverter 12401 according to the general value THD2 of the first level - settable comparison threshold voltage in the two states of the touch panel, i.e., when not touched and when touched. And the sum of the lengths of the two separated line segments 57 and 58 in the figure is the change in the pulse width of the second digital pulse signal generated by the second inverter 12402 according to the general value THD3 of the second level - settable comparison threshold voltage in the two states of the touch panel, i.e., when not touched and when touched. It can be clearly seen that the sum of the lengths of the two separated line segments is less than the length of the single line segment, but it is still usable. And the timing (Window) of the above - mentioned integration can be coordinated with the effective peak region of the AC drive signal, such as Figure 9 shown as 591 and 592 in

[0041] Although the present utility model has been described based on the presently considered most practical and preferred embodiments, it should be understood that the present utility model is not necessarily limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, which are consistent with the broadest interpretation so as to cover all such modifications and similar structures. It will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model, and the scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A position sensing device, characterized in that, The position sensing device is applied to the position sensing of a device under test, and the position sensing device includes: A sensing panel, which includes a first group of electrodes and a second group of electrodes. A first capacitor is formed at the proximity of a first electrode in the first group of electrodes and a second electrode in the second group of electrodes; A signal processing circuit, which is electrically connected to the first group of electrodes and the second group of electrodes and includes a voltage amplifier and a voltage judgment circuit. The signal processing circuit is used to send an AC driving signal from the first electrode in the first group of electrodes, generate a first induction signal at the second electrode through the first capacitor, send the first induction signal and a reference signal into the voltage amplifier, thereby obtaining a first output voltage signal, input the first output voltage signal into the voltage judgment circuit. The voltage judgment circuit has a comparison threshold voltage with a first level that can be set. The voltage judgment circuit outputs a first digital pulse signal according to the voltage magnitude relationship between the comparison threshold voltage with the first level that can be set and the first output voltage signal. According to the difference between the pulse width of the first digital pulse signal within a unit time and a default value, it is further judged whether the device under test is close to the position where the first capacitor is located.

2. The position sensing device according to claim 1, wherein: The device under test is one of a human finger and a capacitive stylus. The AC driving signal is an adjustable digital sine wave signal. By changing the frequency or amplitude of the adjustable digital sine wave signal, the charging voltage and charging time of the capacitor are changed to adjust the waveform of the first induction signal.

3. The position sensing device according to claim 1, wherein: A second capacitor is formed at the proximity between a third electrode adjacent to the second electrode in the second group of electrodes in the sensing panel and the first electrode. The AC driving signal on the first electrode generates a second induction signal at the third electrode through the second capacitor. The second induction signal is used as the reference signal and sent into the voltage amplifier completed by an operational amplifier together with the first induction signal, thereby obtaining the first output voltage signal.

4. The position sensing device according to claim 1, wherein: The voltage judgment circuit includes a first inverter and a second inverter. The first inverter outputs the first digital pulse signal according to the voltage magnitude relationship between the comparison threshold voltage with the first level that can be set and the first output voltage signal. The second inverter outputs a second digital pulse signal according to the voltage magnitude relationship between a comparison threshold voltage with a second level that can be set and the first output voltage signal. According to the change amount of the pulse width of the first digital pulse signal and the second digital pulse signal within the unit time, it is further judged whether the device under test is close to the position where the first capacitor is located.

5. The position sensing device according to claim 1, wherein: It further includes an integrator, which is electrically connected between the voltage amplifier and the voltage judgment circuit. The integrator is used to perform an integration process on the first output voltage signal and then send it into the voltage judgment circuit.

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