KR101133494B1 - Method and apparatus for detecting capacitance in touch sensor, capacitance detecting circuit - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring capacitance of a touch sensor, and a capacitance measuring circuit. In the conventional capacitance measurement technology, the problem of mutual capacitance value not being properly measured by charging sharing, but it is good if the capacitance value of the place to be measured can be known in advance. Since this is not possible, a capacitor of more than a certain size must be implemented. Because of this, it can only be implemented with an external capacitor, and the choice of calculation method with different weights for each panel load is inevitable. Therefore, in the present invention, it is possible to quickly and accurately measure the capacitance change of the panel load of the touch sensor, and to increase the touch sensitivity of the touch sensor, while measuring the capacitance of the touch sensor that is robust to noise. To prepare.

Touch sensor, capacitance, reference voltage

Description

Capacitive measuring device and method of touch sensor, capacitance measuring circuit {METHOD AND APPARATUS FOR DETECTING CAPACITANCE IN TOUCH SENSOR, CAPACITANCE DETECTING CIRCUIT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for measuring capacitance of a touch sensor, and more particularly, to a capacitive measuring device and method of a touch sensor suitable for measuring accurate capacitance change in a short time, and a capacitance measuring circuit. .

In a touch sensor, the capacitance is determined by the contact of a capacitor or an equivalent material or human body with an electrical element connected to the electrode. In this case, the human body may not only directly contact a finger or a specific part of the body with the electrode PAD, but even if the human body does not directly contact the electrode PAD, the electrode PAD may be approached at an unspecified distance. It can be seen that a fine capacitance component is formed between the body and the human body.

In addition, the capacitance changes according to the change of the distance between the adjacent body part and the electrode, which is measured as a result that the capacitance increases as the distance between the electrode and the body gets closer and the capacitance decreases as the distance goes away. .

As such, the distance between the electrode and the human body can be determined to a certain level by measuring the change in capacitance generated by the change of the distance between the electrode and the body part, and the value of a specific critical capacitance is set using the result of the determination. After that, if the capacitance component measured from the electrode is larger than the threshold value, it is determined that the switch is in contact, otherwise it is determined that the switch is non-contact.

The threshold value is determined by experimentally calculating the initial measured value when no contact is made at the power-on time of the touch sensor and the value changed by the surrounding environment, and then subtracting the value from the initial measured value. This is the general way.

In this way, a semiconductor product is a touch sensor IC. Currently, touch sensor ICs are used in many electronic products (mobile phones, TVs, washing machines, air conditioners, microwave ovens, etc.) instead of mechanical switches used in various electronic products.

However, in the touch sensor IC, since the capacitance formed between the electrode and the human body is only a few pF (picofarad) to several tens of pF, various techniques for calculating and measuring this have been proposed.

As part of the conventional capacitance measurement technique, the electrode PAD is completely discharged to ground using an electrical switch, and then the capacitor component of the capacitance generated by the electrode and the human body is charged from the constant current source connected to the voltage to the reference voltage. There is a technique of measuring the value of the capacitance by the value of the timer by measuring the time required by the timer (timer) using a high speed clock (count clock).

This conventional technique has a relatively short time when discharging due to the limitation of the high-speed clock used for measuring capacitance, and a current source that supplies very small current to obtain a sufficient timer value during charging. (current source)

In this way, the smaller the current value is, the more time can be obtained by measuring more timer values. On the other hand, if the current used for charging is too small, the effect on external noise and touch sensor Since the influence of parasitic current inside the semiconductor increases, the amount of change in the time required for charging tends to increase or decrease due to the noise component, and thus, many problems may occur in charging the capacitance efficiently.

As another technique for measuring the capacitance of a conventional touch sensor, the electrode PAD is fully charged to VDD using an electrical switch, and then the capacitance generated by the electrode and the human body through a resistor connected to the ground GND. The time taken to discharge the capacitor component to the reference voltage was measured by a timer using a high speed clock, and the value of the capacitance was measured by the timer value.

This conventional technology also, due to the limitation of the high-speed clock used for measuring capacitance, completes charging in a relatively short time during fast charging, and connects a fairly large resistance of MEGA OHM or more to obtain a sufficient value during discharge. Use it. In this case, in general, when the charge charged in the capacitor is discharged through the resistor, the discharge current uses a fine current of several hundred pA to several uA.

However, in the conventional art, the capacitance obtained between the human finger and the electrode is generally only a few pF to several tens of pF, so as the value of the current to discharge is reduced, more charging time is required and more timer value is obtained. On the other hand, if the current used for charging is too small, the influence of external noise and parasitic current inside the touch sensor semiconductor increases, so the amount of change in the time required for charging is noisy. Because of the tendency to increase or decrease by, many problems arise in measuring the time taken to efficiently charge the capacitance.

In addition, in the conventional capacitance measurement technology, there is a problem in that mutual capacitance values are not properly measured due to charging sharing. That's fine, but you can't, so you'll need to implement a capacitor of a certain size.

Because of this, it can only be implemented with an external capacitor, and the choice of calculation method with different weights for each panel load is inevitable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional situation, and aims to provide a technology for measuring capacitance of a touch sensor that can quickly and accurately measure capacitance change of a panel load of a touch sensor.

In addition, the present invention is to provide a technology for measuring the capacitance of the touch sensor that is robust to noise while increasing the touch sensitivity of the touch sensor.

According to an apparatus for measuring capacitance of a touch sensor for solving the problems of the present invention, a panel driver for driving a panel rod according to a driving reference voltage based on a reference voltage, and the panel in the panel driver It may include a capacitor load detector for detecting the capacitance of the load capacitor of the panel load by detecting the panel load driving current supplied to the load.

The panel driver may include a reference voltage generator for generating a driving reference voltage based on the reference voltage, and an OP for supplying the panel load driving current to the panel load according to a reference voltage applied from the reference voltage generator. It may include an amplifier.

The capacitor load detector may detect the rising and falling of the panel load driving current provided from the panel driver to the panel rod after initialization of the touch sensor.

The capacitor load detector may be enabled when the selection signal is low and is disabled when the selection signal is high, and the selection signal is loil. And a falling current detection unit disabled when the selection signal is high and enabled when the selection signal is high.

The rising current detector may be enabled when the selection signal is low to detect a rising current component in the panel load driving current supplied from the panel driver to the panel load.

In addition, the rising current component may be a current component when the panel load is driven from a low voltage to a high voltage.

The falling current detector may be enabled when the selection signal is high to detect a falling current component in the panel load driving current supplied from the panel driver to the panel rod.

In addition, the falling current component may be a current component when the panel load is driven from a high voltage to a low voltage.

The capacitor load detector may further include a sensing capacitor configured to charge the rising current component or the falling current component.

The capacitor load detector may be configured to adjust the capacitance of the load capacitor of the panel load when the rising current component or the falling current component is charged to the sensing capacitor and the sensing capacitor is fully charged after a predetermined time elapses. Can be detected.

In addition, the capacitance of the load capacitor may be detected when there is no potential change in the sensing voltage of the capacitor load detector.

The capacitor load detector may further include the load voltage of the panel load and the capacitance of the load capacitor equal to the product of the sensing voltage of the capacitor load detector and the capacitance of the sensing capacitor. Capacitance can be detected.

According to the capacitance measuring circuit of the touch sensor for solving the problem of the present invention, the drain terminal of the first PMOS transistor, the drain terminal and the drain terminal of the first PMOS transistor is connected in series and the source terminal A panel driving circuit comprising a first NMOS transistor connected to a ground, a second PMOS transistor having a gate terminal of the first PMOS transistor and a gate terminal thereof connected in series, and a gate of the first NMOS transistor; A second NMOS transistor connected in series with a terminal thereof, a gate terminal thereof, a drain terminal connected in series with a drain terminal of the second PMOS transistor, and a source terminal connected with the ground; a drain terminal of the second NMOS transistor; A third NMOS transistor having a drain terminal connected in series and a source terminal connected to the ground; and the third NMOS transistor; A fourth NMOS transistor having a gate terminal of the jistor connected to the gate terminal thereof in series and a source terminal connected to the ground; a third PMOS transistor having the drain terminal of the fourth NMOS transistor connected in series; And a current detection circuit including a fourth PMOS transistor in which a gate terminal of the third PMOS transistor and a gate terminal thereof are connected in series, and a sensing capacitor in which a drain terminal of the fourth PMOS transistor and one end thereof are connected in series. .

Here, the current value driven through the first PMOS transistor may be equal to the sum of the current value induced to the ground through the second PMOS transistor and the current value driven by the panel driving circuit to the panel load. have.

The second PMOS transistor may be controlled by a gate voltage of the first PMOS transistor to copy a current of the first PMOS transistor.

The second NMOS transistor may be controlled by a gate voltage of the first NMOS transistor to copy a current of the first NMOS transistor.

The fourth NMOS transistor may be controlled by the gate voltage of the third NMOS transistor to copy a current of the third NMOS transistor.

The fourth PMOS transistor may be controlled by a gate voltage of the third PMOS transistor to copy a current of the third PMOS transistor.

In addition, the sensing capacitor may be charged by the current of the third PMOS transistor copied into the fourth PMOS transistor.

In addition, the capacitance measuring circuit of the touch sensor may have a current value driven through the first PMOS transistor and a current value induced to the ground through the second PMOS transistor when the sensing capacitor is fully charged. have.

In addition, when the sensing capacitor is fully charged, the current value driven by the panel driving circuit to the panel load may be zero.

In addition, the current detection circuit, the capacitance of the load capacitor under the condition that the product of the load voltage of the panel load and the capacitance of the load capacitor is equal to the product of the sensing voltage of the current detection circuit and the capacitance of the sensing capacitor. Can be detected.

According to the capacitance measuring method of the touch sensor for solving the problem of the present invention, when the sensing voltage of the touch sensor is initialized to transition the reference voltage from the first setting level to the second setting level that is higher than the first setting level And detecting a sensing capacitance of the touch sensor when the load voltage of the touch sensor converges to the second setting level after a preset time elapses, and measuring the load capacitance of the panel rod of the touch sensor. It may include.

Here, the transition may be a current raising operation.

In addition, the current induced by the panel rod may be a charging current.

According to the capacitance measuring method of the touch sensor for solving the problem of the present invention, when the sensing voltage of the touch sensor is initialized to transition the reference voltage from the second setting level to the first setting level which is a lower level of the second setting level And detecting the sensing capacitance of the touch sensor when the load voltage of the touch sensor converges to the first set level after a preset time elapses, and measuring the load capacitance of the panel rod of the touch sensor. It may include.

Here, the transition may be a current drop operation.

In addition, the current induced by the panel rod may be a discharge current.

According to the present invention, it is possible to accurately detect the change in the capacitance value of the panel load by detecting the rising current and the falling current of the touch sensor, thereby simplifying the circuit implementation while increasing the touch sensitivity. It can provide robustness against noise while increasing data processing speed.

The basic operation of the touch sensor is to detect the amount of change in the panel load capacitance caused by the touch operation. Since the conventional sensing techniques cannot extract an accurate sensing value in the sensing process, the sensing technique is performed with an approximate value. This adds significant complexity to the implementation circuitry and poses a challenge to consider options depending on the panel load size.

In the present invention, to propose a technique that can accurately measure the capacitance value of the panel load.

In the present invention, since the capacitance value of the panel can be accurately measured when driving at a predetermined level regardless of the size of the panel load, the output value is linearly measured by how much touch is made when the touch is made. can do.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, the invention is defined only by the scope of the claims. Like numbers refer to like elements throughout.

In describing the embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the embodiments of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be based on the contents throughout this specification.

Each block of the accompanying block diagrams and combinations of steps of the flowchart may be performed by computer program instructions. These computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment such that instructions executed through the processor of the computer or other programmable data processing equipment may not be included in each block or flowchart of the block diagram. It will create means for performing the functions described in each step. These computer program instructions may be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular manner, and thus the computer usable or computer readable memory. It is also possible for the instructions stored in to produce an article of manufacture containing instruction means for performing the functions described in each block or flowchart of each step of the block diagram. Computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operating steps may be performed on the computer or other programmable data processing equipment to create a computer-implemented process that may be executed by the computer or other programmable data. Instructions for performing data processing equipment may also provide steps for performing the functions described in each block of the block diagram and in each step of the flowchart.

In addition, each block or step may represent a portion of a module, segment or code that includes one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative embodiments, the functions noted in the blocks or steps may occur out of order. For example, the two blocks or steps shown in succession may in fact be executed substantially concurrently or the blocks or steps may sometimes be performed in the reverse order, depending on the functionality involved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of an apparatus for measuring capacitance of a touch sensor according to an exemplary embodiment of the present invention, which includes a panel driver 100 and a panel load 200. , A capacitor load detector 300, and the like.

As shown in FIG. 1, the panel driver 100 serves to drive the panel rod 200 and may include a reference voltage generator 10 and an OP amplifier 12.

Here, the reference voltage generator 10 may serve to apply a constant driving reference voltage to the OP amplifier 12 according to a reference voltage applied from the outside.

The OP amplifier 12 drives the panel load 200 in response to the reference voltage applied from the reference voltage generator 10, wherein the panel load driving current is supplied from the OP amplifier 12 to the panel load 200. Can be.

The panel rod 200 may serve to charge electric charges in the internal load capacitor CL according to the panel load driving current from the OP amplifier 12 of the panel driver 100.

The capacitor load detector 300 according to the present exemplary embodiment detects a panel load driving current supplied from the panel driver 100 to the panel rod 200 to determine the capacitance of the load capacitor CL of the panel rod 200. Can act as a measure

The capacitor load detector 300 may include a selection signal generator 30, a rising current detector 32, a falling current detector 34, a sensing capacitor CS, and the like.

Here, the selection signal generator 30 may generate a high or low selection signal and provide the selected signal to the rising current detector 32 and / or the falling current detector 34.

The rising current detector 32 is enabled when the selection signal from the selection signal generator 30 is low, and is disabled when the selection signal is high, and the panel driver is enabled when the selection signal is high. The rising current component (current component when the panel rod 200 is driven from low voltage to high voltage) is detected in the panel load driving current supplied to the panel rod 200 at 100. It can play a role.

The falling current detection unit 34 is disabled when the selection signal from the selection signal generator 30 is low and is enabled when the selection signal is high, and the panel load is loaded by the panel driver 100 when the selection signal is enabled. The falling current component (the current component when the panel rod 200 is driven from the high voltage to the low voltage) may be detected in the panel load driving current supplied to the 200.

Each of the current components detected by the rising current detector 32 or the falling current detector 34 may be charged in the sensing capacitor CS.

Here, when the current component, for example, the rising current component is charged in the sensing capacitor CS and the sensing capacitor CS is fully charged after a predetermined time, the potential change of the sensing voltage VS no longer occurs. In this embodiment, the capacitance of the load capacitor CL of the panel rod 200 at this time is detected.

FIG. 2 is a circuit diagram illustrating a connection relationship between the OP amp 12 and the rising current detector 32 of FIG. 1 to exemplarily describe a capacitance measurement operation of a touch sensor according to an exemplary embodiment of the present invention. Is a waveform diagram for each signal to help understand the capacitance detection operation.

As illustrated in FIG. 2, the OP amplifier 12 may include a plurality of MOS transistors and resistors, and typically, a drain of the first PMOS transistor M1 and the first PMOS transistor M1. The terminal may include a first NMOS transistor M2 having a drain terminal connected in series and a source terminal connected to a ground (not shown).

The rising current detector 32 includes a gate terminal of the first PMOS transistor M1 of the OP amplifier 12, a second PMOS transistor M3 having a gate terminal thereof connected in series, and an OP amplifier 12. A second NMOS transistor having a gate terminal of the first NMOS transistor M2 and a gate terminal thereof connected in series, a drain terminal thereof connected in series with a drain terminal of the second PMOS transistor M3, and a source terminal thereof connected to ground; M4), the third NMOS transistor M5 in which the drain terminal of the second NMOS transistor M4 and its drain terminal are connected in series, and the source terminal is connected to ground, and the gate terminal of the third NMOS transistor M5; A fourth NMOS transistor M6 having its gate terminal connected in series and a source terminal connected with the ground; and a third PMOS transistor M7 having its drain terminal connected in series with the drain terminal of the fourth NMOS transistor M6; And the third PMOS transistor M7 A fourth PMOS transistor M8 having the gate terminal and the gate terminal connected in series, and a sensing capacitor CS having the drain terminal and one end of the fourth PMOS transistor M8 connected in series may be included.

When the panel load 200 is driven by the load voltage VL waveform of FIG. 3 using the OP amplifier 12, the current I1 driven through the first PMOS transistor M1 is the second PMOS transistor M2. ) Is equal to the sum of the current I2 driven to ground and the current I3 driven by the load. This can be expressed by the following [Equation 1].

I1 = I2 + I3

In this case, since the second PMOS transistor M3 may be controlled by the gate voltage of the first PMOS transistor M1, the second PMOS transistor M3 may copy the current of the first PMOS transistor M1. Can be. Similarly, the second NMOS transistor M4 copies the current of the first NMOS transistor M2, the fourth NMOS transistor M6 copies the current of the third NMOS transistor M5, and the fourth PMOS transistor M8. ) May copy the current of the third PMOS transistor M7.

Here, IM5, which is the current of IM3-IM4, may be induced in the third NMOS transistor M5, which IM5 may be configured, for example, with a diode connection structure.

The current IM5 that can be induced in the third NMOS transistor M5 can be copied into the fourth NMOS transistor M6, and the current IM5 copied into the fourth NMOS transistor M6 is input to the third PMOS transistor M7. Can be.

The current IM5 input to the third PMOS transistor M7 is copied to the fourth PMOS transistor M8 to finally charge the sensing capacitor CS.

After a certain period of time, when the drive is terminated (when the sensing capacitor CS is fully charged), I1 = I2 and the value of I3 becomes 0. As a result, the sensing voltage VS, which is the potential of the sensing capacitor CS, becomes It will not change anymore.

In this manner, the current driven in the panel is accurately charged in the sensing capacitor CS, and the capacitance of the load capacitor CL of the panel load 200 can be accurately detected by Equation 2 below. .

VL × CLc = VS × CSc

Here, VL may refer to a load voltage, CLc may refer to a capacitance of the load capacitor CL, VS may correspond to a sensing voltage, and CSc may refer to a capacitance of the sensing capacitor CS. That is, assuming that VL, VS, and CSc are set in advance, the capacitance CLc of the load capacitor CL satisfying Equation 2 may be detected.

The capacitance measurement operation of the touch sensor of FIG. 2 will be described in more detail with reference to the waveform diagram of each signal of FIG. 3.

First, the sensing voltage VS may be initialized to the ground level at the instant when the initialization signal INIT transitions from low to high.

<Current rise drive>

1. After initialization, when a predetermined time elapses, the reference voltage REF may transition from the first reference voltage Vref1 level to the second reference voltage Vref2 level.

2. This operation can be defined as the current raising operation because the second reference voltage Vref2 is a potential higher than the first reference voltage Vref1. In the current rising operation, the rising current detection unit 32 of the capacitor load detection unit 300 may be enabled by the selection signal of the selection signal generator 30, and the falling current detection unit 34 may be disabled.

3. After sufficient load driving time, e.g., after t1 in FIG. 3, the load voltage VL can fully converge to the second reference voltage Vref2 level.

4. In this process, the current induced by the panel load 200 becomes a charging current, and this value is sensed by the rising current detector 32 and stored in the sensing capacitor CS, and the sensing voltage after t1 passes. Can end with a value having a potential of (VS).

<Current lowering drive>

1. After initialization, when a predetermined time elapses, the reference voltage REF may transition from the second reference voltage Vref2 level to the first reference voltage Vref1 level.

2. This operation can be defined as the current drop operation because the second reference voltage Vref2 is a potential larger than the first reference voltage Vref1. In the current lowering operation, the falling current detection unit 34 of the capacitor load detection unit 300 may be enabled by the selection signal of the selection signal generator 30, and the rising current detection unit 34 may be disabled.

3. After sufficient load driving time elapses, for example, t1 in FIG. 3, the load voltage VL may completely converge to the first reference voltage Vref1 level.

4. In this process, the current induced by the panel load 200 becomes a discharging current, and this value is sensed by the rising current detector 32 and stored in the sensing capacitor CS, and the sensing voltage after t1 passes. Can end with a value having a potential of (VS).

The waveform diagram of FIG. 3 means a timing diagram of initialization-> current rise drive-> current fall drive-> current rise drive-> current fall drive.

It can be seen that the sensing voltage VS is charged by a predetermined potential at the end of each driving. The capacitance of the panel load 200 may be measured using the measured voltage.

4A to 4C are graphs comparing the simulation result by the capacitance measurement operation of the touch sensor according to the embodiment of the present invention with the simulation result by the capacitance measurement operation of the conventional touch sensor.

First, FIG. 4A illustrates measurement waveforms when mutual capacitance CM and sensing capacitance CS are set to 1: 1, and FIG. 4B illustrates mutual capacitance CM and sensing. This is a measurement waveform when the capacitance CS is set to 1:10, and FIG. 4C illustrates a measurement waveform when the mutual capacitance CM and the sensing capacitance CS are set to 1: 100.

As illustrated in the figure, it can be seen that the capacitance measuring method in this embodiment is very superior in accuracy compared to the conventional capacitance measuring method.

As described above, in the present embodiment, after initialization of the touch sensor, the panel driver detects the rise and fall of the current provided to the panel load, and the product of the load voltage and the capacitance of the load capacitor is determined by the sensing voltage and the sensing capacitor. By detecting the capacitance of the load capacitor under the same condition as the product of the capacitance, the capacitance change of the panel load of the touch sensor can be measured quickly and accurately.

1 is a schematic block diagram of a capacitive detection device of a touch sensor according to an embodiment of the present invention;

FIG. 2 is a circuit diagram illustrating an example of a capacitive detection operation of a touch sensor according to an exemplary embodiment of the present invention, and illustrates a connection relationship between the OP amplifier 12 and the rising current detector 32 of FIG. 1.

3 is a waveform diagram for each signal for explaining a capacitive detection operation of a touch sensor according to an embodiment of the present invention;

4A to 4C are graphs comparing simulation results by a capacitance detection operation of a touch sensor according to an embodiment of the present invention with simulation results by a capacitance detection operation of a conventional touch sensor.

<Explanation of symbols for the main parts of the drawings>

100: panel drive unit

10: reference voltage generator

12: OP amplifier

200: panel load

300: capacitor load detection unit

30: selection signal generator

32: rising current detector

34: falling current detector

Claims (28)

A panel driver for driving the panel load according to the driving reference voltage based on the reference voltage; And a capacitor load detector configured to detect a panel load driving current supplied from the panel driver to the panel rod to detect capacitance of the panel rod. Capacitive measuring device of touch sensor. The method of claim 1, The panel driver, A reference voltage generator for generating a driving reference voltage based on the reference voltage; And an OP amplifier configured to supply the panel load driving current to the panel load according to a reference voltage applied from the reference voltage generator. Capacitive measuring device of touch sensor. The method of claim 1, The capacitor load detector detects the rise and fall of the panel load driving current provided from the panel driver to the panel rod after initialization of the touch sensor. Capacitive measuring device of touch sensor. The method of claim 1, The capacitor load detector, A rising current detection unit that is enabled when the selection signal is low and is disabled when the selection signal is high; And a falling current detection unit disabled when the selection signal is low and enabled when the selection signal is high. Capacitive measuring device of touch sensor. The method of claim 4, wherein The rising current detector detects a rising current component in the panel load driving current supplied from the panel driver to the panel rod when the selection signal is low. Capacitive measuring device of touch sensor. The method of claim 5, The rising current component is a current component when the panel load is driven from a low voltage to a high voltage. Capacitive measuring device of touch sensor. The method of claim 4, wherein The falling current detector is enabled when the selection signal is high to detect a falling current component in the panel load driving current supplied from the panel driver to the panel rod. Capacitive measuring device of touch sensor. The method of claim 7, wherein The falling current component is a current component when the panel load is driven from a high voltage to a low voltage. Capacitive measuring device of touch sensor. The method according to claim 5 or 7, The capacitor load detector, Further comprising a sensing capacitor for charging the rising current component or the falling current component Capacitive measuring device of touch sensor. The method of claim 9, The capacitor load detector, Detecting the capacitance of the panel rod when the rising current component or the falling current component is charged to the sensing capacitor and the sensing capacitor is fully charged after a predetermined time elapses. Capacitive measuring device of touch sensor. 11. The method of claim 10, The capacitance of the panel rod is detected when there is no change in potential of the sensing voltage of the capacitor rod detector. Capacitive measuring device of touch sensor. The method of claim 11, The capacitor load detector, Detecting the capacitance of the panel load under a condition that the product of the load voltage of the panel rod and the capacitance of the panel rod is equal to the product of the sensing voltage of the capacitor load detector and the capacitance of the sensing capacitor. Capacitive measuring device of touch sensor. A first PMOS transistor, A first NMOS transistor having a drain terminal of the first PMOS transistor and a drain terminal thereof connected in series and a source terminal connected to ground Including a panel drive circuit consisting of, A second PMOS transistor having a gate terminal of the first PMOS transistor and a gate terminal thereof connected in series; A second NMOS transistor in which a gate terminal of the first NMOS transistor and a gate terminal thereof are connected in series, a drain terminal thereof is connected in series with a drain terminal of the second PMOS transistor, and a source terminal thereof is connected with the ground; A third NMOS transistor having a drain terminal connected to the drain terminal of the second NMOS transistor in series and a source terminal connected to the ground; A fourth NMOS transistor having a gate terminal of the third NMOS transistor and a gate terminal thereof connected in series and a source terminal connected to ground; A third PMOS transistor having a drain terminal of the fourth NMOS transistor and a drain terminal thereof connected in series; A fourth PMOS transistor having a gate terminal of the third PMOS transistor and a gate terminal thereof connected in series; A sensing capacitor having a drain terminal of the fourth PMOS transistor and one end thereof connected in series Current detection circuit Capacitive measurement circuit of the touch sensor comprising a. The method of claim 13, The current value driven through the first PMOS transistor is Is equal to the sum of the current value induced through the second PMOS transistor to the ground and the current value driven by the panel driving circuit to the panel load. Capacitive measurement circuit of touch sensor. The method of claim 13, The second PMOS transistor is controlled by the gate voltage of the first PMOS transistor to copy a current of the first PMOS transistor. Capacitive measurement circuit of touch sensor. The method of claim 13, The second NMOS transistor is controlled by a gate voltage of the first NMOS transistor to copy current of the first NMOS transistor. Capacitive measurement circuit of touch sensor. The method of claim 13, The fourth NMOS transistor is controlled by the gate voltage of the third NMOS transistor to copy current of the third NMOS transistor. Capacitive measurement circuit of touch sensor. The method of claim 13, The fourth PMOS transistor is controlled by the gate voltage of the third PMOS transistor to copy current of the third PMOS transistor. Capacitive measurement circuit of touch sensor. The method of claim 18, The sensing capacitor is charged by the current of the third PMOS transistor copied to the fourth PMOS transistor. Capacitive measurement circuit of touch sensor. The method of claim 19, The capacitance measuring circuit of the touch sensor, When the sensing capacitor is fully charged, a current value driven through the first PMOS transistor and a current value induced to the ground through the second PMOS transistor are the same. Capacitive measurement circuit of touch sensor. The method of claim 20, When the sensing capacitor is fully charged, the current value driven by the panel driving circuit to the panel load is 0. Capacitive measurement circuit of touch sensor. The method of claim 14, The current detection circuit, Detecting the capacitance of the load capacitor under a condition that the product of the load voltage of the panel load and the capacitance of the load capacitor is equal to the product of the sensing voltage of the current detection circuit and the capacitance of the sensing capacitor. Capacitive measurement circuit of touch sensor. Translating the reference voltage from the first setting level to a second setting level that is higher than the first setting level when the sensing voltage of the touch sensor is initialized; Detecting a sensing capacitance of the touch sensor and measuring a load capacitance of the panel load of the touch sensor when the load voltage of the touch sensor converges to the second setting level after a preset time elapses; How to measure capacitance of touch sensor. The method of claim 23, wherein The transition process is a current raising operation How to measure capacitance of touch sensor. The method of claim 23, wherein The current induced by the panel rod is a charging current How to measure capacitance of touch sensor. Transitioning a reference voltage from a second setting level to a first setting level which is a lower level of the second setting level when the sensing voltage of the touch sensor is initialized; Detecting a sensing capacitance of the touch sensor and measuring a load capacitance of the panel load of the touch sensor when a load voltage of the touch sensor converges to the first set level after a preset time elapses; How to measure capacitance of touch sensor. The method of claim 26, The transition process is a current drop operation How to measure capacitance of touch sensor. The method of claim 26, The current induced by the panel rod is a discharge current How to measure capacitance of touch sensor.

Images