KR20210012132A - High sensitivity touch sensor - Google Patents

Abstract

The present invention relates to a high-sensitivity touch sensor in which a touch sensitivity is improved by compensating for a loss of a driving applied voltage and a touch sensitivity sensing time is shortened. More specifically, the present invention relates to a high-sensitivity touch sensor that includes: a voltage accumulating unit including a first capacitor; a touch sensing unit including a touch capacitor and a second capacitor connected in parallel to the touch capacitor; a voltage loss compensating unit including a third capacitor having a capacity equal to that of the second capacitor; a switching unit operating in a normal mode, a high sensitivity mode, and a correction mode according to a setting state; and a signal comparison unit configured to generate a comparison signal (Vcom) by comparing a voltage level of an opposite terminal of the first capacitor with a preset reference voltage (VREF).

Description

High sensitivity touch sensor {HIGH SENSITIVITY TOUCH SENSOR}

The present invention relates to a high-sensitivity touch sensor, and more particularly, to a high-sensitivity touch sensor in which a loss of a driving voltage is compensated to improve touch sensitivity and a touch sensitivity sensing time is shortened.

The touchscreen panel, also referred to as a touch panel, refers to a computing input device that enables interactive and intuitive operation by touching a button displayed on a display to easily operate a computer. The capacitive touch panel is a method that uses the capacitance in the human body. The capacitive touch panel is a method of recognizing a touch by measuring the change in resistance and current caused by a person's capacitance using an alternating voltage, and a method of determining the presence or absence of a touch by comparing the amount of a capacitor charged. I can share. Such a capacitive touch panel has excellent durability compared to a resistive film type using a film, and thus does not interfere with operation even with moisture or small damage. In addition, the touch accuracy is relatively high and the optical characteristics are excellent, so the screen is clear. Particularly, a touch panel using a capacitive charging method is widely used in mobile smart devices because multiple points are possible and can be manufactured in a small size.

On the other hand, although a charge sharing method is widely used as a capacitive method, a problem has been raised in that the touch sensor according to the conventional charge distribution method is inferior in high sensitivity characteristics for detecting a fine touch.

In addition, various types of electronic devices have been recently developed and manufactured using capacitive touch sensor ICs. Accordingly, sensitivity measurement, tuning, and threshold level (THD) for each sensing channel are performed whenever a touch sensor IC is mounted and developed. Level) setting work has to be done one by one, so development time is lengthened and development methods are inconvenient.

(0001) Domestic registered patent No. 10-1285686

The technical problem to be solved by the present invention is to provide a high-sensitivity touch sensor in which a loss rate of a driving voltage is partially compensated and the time to fall to a set reference voltage is delayed, thereby improving touch sensitivity and shortening the touch sensing time.

Another technical problem to be solved by the present invention is to set the capacitance value of each channel in advance in order to simplify the process of developing sensitivity tuning due to the difference in parasitic capacitance value according to the difference in wiring length of each capacitance sensing channel when designing a circuit. It is to provide a high-sensitivity touch sensor that automatically compensates to become a standard capacitance.

A high-sensitivity touch sensor according to the present invention for achieving the above technical problem includes: a voltage accumulating unit including a first capacitor to which a first driving voltage (VDD) is applied to one terminal; A touch sensing unit including a touch capacitor that senses a user's touch through one terminal and a second capacitor connected in parallel to the touch capacitor; Voltage loss compensation unit including a third capacitor that operates in response to a plurality of switching control signals (SVD, SVS) and has a capacity equal to that of the second capacitor by performing a preset capacity setting step ; Operates in response to a plurality of switching control signals (S1N to S3N, S1D to S3D), and in normal mode, a switching operation between the first driving voltage and the other terminal of the first capacitor, and between the voltage accumulating unit and the touch sensing unit A charge sharing operation is performed between the first capacitor and the second capacitor through a switching operation of, and in the high-sensitivity mode, a switching operation between the second driving voltage VHS and the other terminal of the first capacitor and The loss of the first driving voltage in the first capacitor and the second capacitor generated during the charge distribution operation through a switching operation between the voltage accumulating unit, the touch sensing unit, and the voltage loss compensating unit is calculated. A switching unit for performing a charge compensation operation using a third capacitor and transferring the charge to the other terminal of the first capacitor; And a signal comparing unit for generating a comparison signal Vcom by comparing the voltage level of the other terminal of the first capacitor with a preset reference voltage VREF, wherein the voltage level of the first driving voltage is the It is characterized in that it is higher than the voltage level of the second driving voltage.

Further, it characterized in that it further comprises a touch determination signal generation unit for processing the comparison signal (Vcom) to generate a touch determination signal (VOUT) reflecting the fluctuation in a certain range of the comparison signal.

In addition, it characterized in that it further comprises a; digital processing unit for generating the plurality of switching control signals (SVD, SVS, S1N ~ S3N, S1D ~ S3D).

Further, in the high-sensitivity mode, a second driving voltage generation unit generating the second driving voltage and supplying the second driving voltage to the voltage accumulating unit is further included.

In addition, the switching unit may include a first switch opening and closing between the first driving voltage and the (+) input terminal of the signal comparison unit; A second switch opening and closing between the second driving voltage and the (+) input terminal of the signal comparison unit; A third switch opening and closing between the touch sensing unit and the ground; A fourth switch opening and closing between the touch sensing unit and the voltage accumulating unit; And a fifth switch opening and closing between the voltage loss compensating unit and the voltage accumulating unit.

In addition, the voltage loss compensation unit may include the third capacitor; A sixth switch connected in parallel with the third capacitor; A seventh switch to which a first driving voltage is connected to the other terminal in the high-sensitivity mode; And an eighth switch in which the other terminal is connected to the ground, wherein a common terminal connected to one terminal of each of the third capacitor and the sixth switch is connected to the fifth switch, and the third capacitor and the sixth switch A common terminal connected to the other terminal of each switch is connected to a common terminal connected to one terminal of each of the seventh switch and the eighth switch.

In addition, the signal comparison unit is characterized in that a (+) input terminal is connected to the voltage accumulating unit, and a (-) input terminal is connected to a digital to analog converter (DAC) that generates the reference voltage.

In addition, the second driving voltage generator is characterized in that the (+) input terminal is configured with a buffer connected to a digital-to-analog converter (DAC) generating the two driving voltages.

Further, in the capacity setting step, after storing the count value of the second capacitor in the normal mode, a capacity corresponding to the stored count value is set in the third capacitor.

In addition, in the correction mode, a plurality of the touch sensing units and the voltage loss compensating unit are connected, and after determining the capacity of the second capacitor of each of the touch sensing units, the remaining second capacitor is adjusted according to the value of the second capacitor having the largest capacity. It is characterized in that the capacity of the second capacitor is equally adjusted by performing a charge compensation operation using the third capacitor.

In addition, the first capacitor, the second capacitor and the third capacitor are characterized in that it is composed of a variable capacitor.

The high-sensitivity touch sensor according to the present invention described above has the following effects.

First, since it can operate in a normal mode, a high sensitivity mode, and a correction mode through switching control, it is possible to implement a multi-mode with one system, improve convenience of use, and reduce manufacturing cost.

In addition, the sensitivity can be improved by performing a charge compensation operation using a third capacitor for the loss of the first driving voltage, and at this time, improved sensitivity detection time by using the second driving voltage generated through the second driving voltage generator. High sensitivity detection is possible by shortening

In addition, fine voltage adjustment is possible by supplying power using a 10-bit digital-to-analog converter.

In addition, by using the C value-related auto-calibration function, which adds each channel's own corrective capacitance to the corresponding channel, the same sensitivity for each channel, regardless of touch sensors having different wire lengths. A value can be formed, and the same single THD (Threshold) level can be set accordingly, thus simplifying the development process for sensitivity tuning, thereby facilitating development and further shortening the development period.

1 is a diagram showing a basic circuit configuration state of a high-sensitivity touch sensor according to the present invention;
2 is a block diagram of a basic circuit of a high-sensitivity touch sensor according to the present invention,
3 is a block diagram of FIG. 2;
4 is a diagram showing a circuit connection state in a normal mode according to the present invention;
5 is a view showing an actual circuit connection state of FIG. 4;
6 is a diagram showing an operation timing in a normal mode according to the present invention;
7 is a diagram showing a circuit connection state in an offset calibration mode according to the present invention;
8 is a diagram showing an actual circuit connection state of FIG. 7;
9 is a diagram showing an operation timing in an offset calibration mode according to the present invention;
10 is a diagram showing a circuit connection state in a high sensitivity mode according to the present invention;
11 is a view showing an actual circuit connection state of FIG. 10;
12 is a diagram showing an operation timing in a high sensitivity mode according to the present invention;
13 is a diagram showing a difference in sensitivity in a normal mode and in a high sensitivity mode according to the present invention;
14 is a diagram showing a circuit connection state in a correction mode according to the present invention;
15 is a view showing an actual circuit connection state of FIG. 14;
16 is a diagram showing an operation timing in a correction mode according to the present invention;
17 is a view showing a switching state in each mode according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to elements of each drawing, it should be noted that the same elements are assigned the same numerals as possible even if they are indicated on different drawings. In addition, in describing the embodiments of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiments of the present invention, the detailed description thereof will be omitted.

In addition, in describing the constituent elements of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but another component between each component It should be understood that may be “connected”, “coupled” or “connected”.

1 is a diagram showing a basic circuit configuration state of a high-sensitivity touch sensor according to the present invention, FIG. 2 is a diagram illustrating a basic circuit of a high-sensitivity touch sensor according to the present invention for each block, and FIG. 3 is a block diagram of FIG.

First, a configuration state of the high-sensitivity touch sensor according to the present invention will be described with reference to FIGS. 1 to 3.

The high-sensitivity touch sensor of the present invention includes a voltage accumulating unit 100, a touch sensing unit, a voltage loss compensation unit 300, a switching unit 400, a signal comparison unit 500, a touch determination signal generation unit 600, and a second It is configured to include a driving voltage generator 700. In addition, although not shown, a digital processing unit connected to each of the configuration units listed above to control each configuration unit is further included, and the structure, connection state, and function of the digital processing unit are known technologies, so detailed descriptions thereof will be omitted. Do it. In addition, since the sensing channel PAD configuration and the CAPN PAD configuration of FIG. 1 are also generally known technologies, detailed descriptions will be omitted, and the main components of the present invention are illustrated in FIG.

The voltage accumulating unit 100 includes a first capacitor 110 having a capacity of several tens of nanofarads (nF). A first driving voltage VDD is applied to one terminal of the first capacitor 110, and the other terminal of the first capacitor 110 is connected to the (+) input terminal of the signal comparison unit 500. It is preferable that the first capacitor 110 has a different capacitor value depending on the application. The voltage accumulating unit 100 is a part that is mounted outside a chip as a part in which a sensing signal is modulated by a capacitor having a large capacity by charge sharing, that is, a charge distribution method. For reference, in FIG. 1, the red part is a part configured outside the chip, and the green and blue parts are part built inside the chip.

The touch sensing unit 200 includes a touch capacitor 210 and a second capacitor 220. The second capacitor 220 senses whether a user touches with one terminal. That is, touch sensing is performed to sense a signal, and is usually composed of a capacitor of tens of picofarads (pF) capacity, and includes a PCB line or sensing pattern. When a person's hand touches the second capacitor 220, a capacitor component generated by the touch capacitor 210 appears. It has a structure to detect. The touch capacitor 210 generated by a human hand is connected to the second capacitor 220 in parallel. The touch capacitor 210 and the second capacitor 220 are connected to the first capacitor 110 by the switching unit 400 to perform a charge distribution operation.

The voltage loss compensator 300 includes a third capacitor 310, a sixth switch 320, a seventh switch 330, and an eighth switch 340.

The voltage loss compensation unit 300 is adjusted to be set to have the same capacitance as the touch sensing unit 200 for high-sensitivity sensing. That is, it operates in response to a plurality of switching control signals (SVD, SVS) generated by the digital processing unit, and performs a preset capacity setting step to have a capacity equal to that of the second capacitor 220. A third capacitor 310 is included. In the capacity setting step, after storing the count value of the second capacitor 220 in the normal mode, a capacity corresponding to the stored count value is set in the third capacitor 310.

A resistor (not shown) may be connected to one terminal of the third capacitor 310, and the sixth switch 320 operates in response to a'S2D' signal, and is connected in parallel with the third capacitor 310. It is preferable that the third capacitor 310 is also configured as a variable capacitor. The seventh switch 330 operates in response to the'SVD' signal, and the first driving voltage is connected to the other terminal in the high sensitivity mode. The eighth switch 340 operates in response to the'SVS' signal, and the other terminal is connected to the ground. A common terminal connected to one terminal of each of the third capacitor 310 and the sixth switch 320 is connected to the fifth switch 450. In addition, a common terminal connected to the other terminal of each of the third capacitor 310 and the sixth switch 320 is connected to a common terminal connected to one terminal of each of the seventh switch 330 and the eighth switch 340.

The switching unit 400 is configured to include a first switch 410, a second switch 420, a third switch 430, a fourth switch 440, and a fifth switch 450.

The first switch 410 has one end connected to the first driving voltage, the other end connected to the (+) input terminal of the signal comparison unit 500, and operates in response to the'S1N' signal to compare the first driving voltage and the signal. Opens and closes between the (+) input terminals of (500).

The second switch 420 has one end connected to the second driving voltage, the other end connected to the (+) input terminal of the signal comparison unit 500, and operates in response to the'S1D' signal to compare the signal with the second driving voltage. Opens and closes between the (+) input terminals of the sub 500.

The third switch 430 has one end connected to the touch sensing unit 200, the other end connected to the ground, and operates in response to a'S2N' signal to open and close between the touch sensing unit 200 and the ground.

The fourth switch 440 has one end connected to the touch sensing unit 200, the other end connected to the voltage accumulating unit 100, and operates in response to the'S3N' signal to provide the touch sensing unit 200 and the voltage accumulating unit. (100) to open and close.

The fifth switch 450 has one end connected to the voltage accumulating unit 100, and the other end connected to a common terminal at one end of the third capacitor 310 and the sixth switch 320 of the voltage loss compensating unit 300. , Opens and closes between the voltage loss compensating unit 300 and the voltage accumulating unit 100 by operating in response to the'S3D' signal.

The switching unit 400 generates a charge distribution operation by initializing the first capacitor 110 and a switching operation between the first capacitor 110 and the second capacitor 220. That is, the switching unit 400 operates in response to a plurality of switching control signals (S1N to S3N, S1D to S3D) generated by the digital processing unit (not shown), and operates in a normal mode, a high sensitivity mode, and a correction mode. It works.

In the general mode, it is the same as the conventional charge distribution method, and the switching operation between the first driving voltage and the other terminals of the first capacitor 110 and the switching operation between the voltage accumulating unit 100 and the touch sensing unit 200 is performed. Through this, a charge sharing operation is performed between the first capacitor 110 and the second capacitor 220.

In the high-sensitivity mode, switching between the second driving voltage (VHS) and the other terminals of the first capacitor 110 and switching between the voltage accumulating unit 100, the touch sensing unit 200, and the voltage loss compensating unit 300 Through the operation, the loss of the first driving voltage in the first capacitor 110 and the second capacitor 220 generated during the charge distribution operation is performed by performing a charge compensation operation using the third capacitor 310 to perform the first It is transmitted to the other terminal of the capacitor 110.

In the correction mode, a plurality of touch sensing units 200, that is, a plurality of touch channels and a voltage loss compensation unit 300, are connected. In the correction mode, after determining the capacity of each second capacitor 220 of the touch sensing unit 200, the capacity of the other second capacitors 220 is adjusted according to the value of the second capacitor 220 having the largest capacity. Adjust to have the same value by performing the charge compensation operation using 310).

The signal comparison unit 500 generates a comparison signal Vcom by comparing the voltage level of the other terminal of the first capacitor 110 with a preset reference voltage VREF. A first driving voltage (VDD) or a second driving voltage (VHS) is connected to the (+) input terminal of the signal comparison unit 500, and a reference voltage (VREF) is generated at the (-) input terminal of the signal comparison unit 500. A VREF generation circuit (not shown in the drawing) is connected. It is preferable to use a 10-bit digital-to-analog converter (DAC) that generates a reference voltage as the VREF generation circuit, and minute voltage adjustment and setting are possible through a 10b DAC. The signal comparison unit 500 determines an output signal by comparing a voltage generated by charge distribution with a reference voltage determined by an internal 10b DAC.

Meanwhile, the voltage level of the first driving voltage is set higher than the voltage level of the second driving voltage. The second driving voltage is a voltage applied in the high-sensitivity mode and has a voltage level lower than that of the first driving voltage, thereby reducing the detection time of improved sensitivity compared to the normal mode.

The touch detection signal generation unit 600 processes the comparison signal Vcom generated by the signal comparison unit 500 using a Schmitt trigger circuit, and the touch status reflects the variation in a certain range of the comparison signal. A determination signal VOUT is generated. That is, when the voltage through the signal comparison unit 500 is an unstable signal, the signal is filtered and processed into a stable signal.

The second driving voltage generation unit 700 generates a second driving voltage in the high-sensitivity mode and supplies it to the voltage accumulating unit 100. The second driving voltage generation unit 700 is composed of a buffer connected to a digital-to-analog converter (DAC) in which the (+) input terminal generates two driving voltages, thereby providing stable power.

Hereinafter, circuit operation states according to the normal mode, the high sensitivity mode, and the correction mode will be described.

4 is a diagram showing a circuit connection state in a normal mode according to the present invention, FIG. 5 is a diagram illustrating an actual circuit connection state of FIG. 4, and FIG. 6 is a view showing an operation timing in a normal mode according to the present invention.

Referring to FIGS. 4 to 6, a circuit operation state in the normal mode operation according to the present invention will be described as follows.

The general mode is the same as the conventional charge distribution method and is the most basic sensing structure. First, in FIG. 4, a part to which a red signal is applied represents a switch that is actually open/closed, and a part to which a black signal is applied represents a switch that exists in an open state so as not to operate. Therefore, description will be made with reference to FIGS. 5 and 6 configured only with an actual operation circuit.

First, the first switch 410 is closed through the'S1N' signal and is set as the first driving voltage. At this time, the third switch 430 and the fourth switch 440 are applied through the'S2N' signal and the'S3N' signal. ) Is open. Thereafter, the first switch 410 is opened through the'S1N' signal, and the third switch 430 and the fourth switch 440 are alternately opened and closed through the'S2N' signal and the'S3N' signal. That is, a large charge by the first driving voltage is formed in the first capacitor 110, which is the first CAPN. Thereafter, the fourth switch 440 is opened through the'S3N' signal and the third switch 430 is closed through the'S2N' signal, thereby making the potential of the second capacitor 220 zero. Thereafter, when the third switch 430 is opened through the'S2N' signal and the fourth switch 440 is closed through the'S3N' signal, the first capacitor 110 and the second capacitor 220 are connected to the first capacitor. A large charge of 110 moves to the second capacitor 220 by the amount of the second capacitor 220. When the charge moved from the first capacitor 110 is formed in the second capacitor 220, the third switch 430 is closed again through the'S2N' signal, and the fourth switch 440 is opened through the'S3N' signal. By opening, the charge formed in the second capacitor 220 flows through the ground to form a potential of zero again. Thereafter, when the above-described operation is repeated, a large charge of the first capacitor 110 decreases by the capacity of the second capacitor 220, and the first driving voltage VDD decreases to the set reference voltage VREF. At this time, after setting the reset voltage through the first switch 410, starting from the state in which the third switch 430 is operated, the time until the point where the first driving voltage VDD falls to the reference voltage VREF is checked. Then, the checked first count value is stored. The checked first count value becomes a count value in a general situation, and when the user touches the touch capacitor 210 by hand, the capacitor capacity of the entire touch sensing unit 200 increases. Accordingly, the time when the first driving voltage VDD falls to the reference voltage VREF when the above-described operation is repeated is shortened. Likewise, until the point where the first driving voltage VDD falls to the reference voltage VREF even when touched. Check the time of and store the checked second count value. The digital processing unit determines whether a touch has been made based on a first count value and a second count value.

However, in the normal mode, it indicates a touch sensing mode in a general situation, and when the area of the touch pad is small or when it is necessary to detect even a minute touch with a very small capacity of the second capacitor 220, it is switched to the next high-sensitivity mode. Can be used.

Meanwhile, in order to switch in the high-sensitivity mode, an offset-calibration sensing mode operation must be performed first.

FIG. 7 is a diagram showing a circuit connection state in an offset calibration mode according to the present invention, FIG. 8 is a view showing an actual circuit connection state of FIG. 7, and FIG. 9 is a view showing an operation timing in an offset calibration mode according to the present invention. to be.

A circuit operation state in the offset calibration mode according to the present invention will be described with reference to FIGS. 7 to 9.

The offset calibration sensing mode is an operation of equally setting the capacities of the second capacitor 220 (Cpad) outside the chip and the third capacitor 310 (Cint) inside the chip. First, in FIG. 7, a part to which a red signal is applied represents a switch that is actually open/closed, and a part to which a black signal is applied represents a switch that exists in an open state so as not to operate. Therefore, description will be made with reference to FIGS. 8 and 9 configured only with an actual operation circuit.

First, it proceeds to the normal mode and stores a count value when no-touch, that is, the first count value. Thereafter, in the normal mode, a process of finding the value of the third capacitor 310 corresponding to the offset calibration count value equal to the first count value.

That is, the offset calibration count value is set as the first driving voltage by closing the first switch 410 through the'S1N' signal, referring to FIG. 9, and at this time, through the'S3D' signal and the'S2D' signal. The fifth switch 450 and the sixth switch 320 are opened. Thereafter, the first switch 410 is opened through the'S1N' signal, and the fifth switch 450 and the sixth switch 320 are alternately opened and closed through the'S3D' signal and the'S2D' signal. That is, a large charge by the first driving voltage is formed in the first capacitor 110, which is the first CAPN. Thereafter, the fifth switch 450 is opened through the'S3D' signal and the sixth switch 320 is closed through the'S2D' signal to make the potential of the third capacitor 310 to zero. Thereafter, when the fifth switch 450 is closed through the'S3D' signal and the sixth switch 320 is opened through the'S2D' signal, the first capacitor 110 and the third capacitor 310 are connected and the first capacitor. A large charge of 110 moves to the third capacitor 310 as much as the capacity of the third capacitor 310. When the charge moved from the first capacitor 110 is formed in the third capacitor 310, the fifth switch 450 is opened again through the'S3D' signal and the sixth switch 320 is closed through the'S2D' signal. By doing so, the charge formed in the third capacitor 310 flows through the ground to form a potential of zero again. Thereafter, when the above-described operation is repeated, the large charge of the first capacitor 110 decreases by the capacity of the third capacitor 310, and the first driving voltage VDD decreases to the set reference voltage VREF. At this time, starting from the state in which the sixth switch 320 is operated after setting the first driving voltage VDD through the first switch 410, the point where the first driving voltage VDD falls to the reference voltage VREF Check the time until and save the checked count value. The checked count value becomes the offset calibration count value.

After performing the offset calibration sensing mode as described above, the high sensitivity mode is performed.

10 is a diagram showing a circuit connection state in a high-sensitivity mode according to the present invention, FIG. 11 is a diagram showing an actual circuit connection state of FIG. 10, and FIG. 12 is a view showing an operation timing in a high-sensitivity mode according to the present invention 13 is a diagram showing a difference in sensitivity in a normal mode and in a high sensitivity mode according to the present invention.

The high-sensitivity mode is performed after the offset calibration sensing mode is performed.

First, in FIG. 10, a part to which a red signal is applied represents a switch that is actually open/closed, and a part to which a black signal is applied represents a switch that exists in an open state so as not to operate. Accordingly, description will be made with reference to FIGS. 11 and 12 configured only with an actual operation circuit.

The high-sensitivity mode is a structure to increase the sensitivity (ΔT), and first, the third capacitor 310 is set by performing an adjustment operation so that the third capacitor 310 and the second capacitor 220 have the same value. Thereafter, the charge of the first capacitor 110 decreases due to the charge distribution by the second capacitor 220, and the third capacitor 310 operates in the opposite direction to the second capacitor 220, and the second capacitor 220 The sensitivity is increased by compensating for the charge of the first capacitor 110 reduced by That is, by delaying the time when the second driving voltage VHS falls to the reference voltage VREF, the sensitivity is increased.

First, the second switch 420 is closed through the'S1D' signal and set as the second driving voltage (VHS). At this time, the third switch 430 and the sixth switch are connected through the'S2N' signal and the'S2D' signal. The switch 320 is simultaneously opened, and the fourth switch 440 and the fifth switch 450 are also simultaneously opened through the'S3N' signal and the'S3D' signal. Thereafter, the third switch 430 and the sixth switch 320 and the fourth switch 440 and the fifth switch 450 are alternately opened and closed. That is, a charge smaller than the first driving voltage VDD by the second driving voltage VHS is formed in the first capacitor 110 that is the first CAPN. Thereafter, the third switch 430 and the sixth switch 320 are simultaneously closed through the'S2N' signal and the'S2D' signal, thereby reducing the potential of the second capacitor 220 to zero and making the third capacitor 310 second. It consists of a potential corresponding to the capacity of the capacitor 220. Thereafter, the third switch 430 and the sixth switch 320 are simultaneously opened through the'S2N' signal and the'S2D' signal, and the fourth switch 440 and the fifth switch are simultaneously opened through the'S3N' and'S3D' signals. When the switch 450 is closed at the same time, the first capacitor 110 and the second capacitor 220 are connected so that a large charge of the first capacitor 110 is equal to the capacity of the second capacitor 220 to the second capacitor 220. While moving, the third capacitor 310 and the first capacitor 110 are also connected to compensate the value of the first capacitor 110 with the value of the third capacitor 310, and the above-described operation is repeated.

Accordingly, it takes more time than the normal mode before the first applied second driving voltage VHS decreases to the set reference voltage VREF. Referring to FIG. 13, a dotted line indicates a touch state, and a solid line indicates a no-touch state. Fig. 13(A) shows the sensitivity (1) and the sensing time (1) in the normal mode, and Fig. 13(B) shows the sensitivity (2) and the sensing time (2) in the high sensitivity mode. Even in the high-sensitivity mode, when the initial voltage is VDD, the voltage loss compensator has almost no compensation charge for the third capacitor, so it operates similarly to the normal mode, but when the voltage gradually decreases, the compensation charge increases and the sensitivity increases. Will operate as. Although the sensitivity (2) in the high-sensitivity mode is clearly increased, it can be seen that the sensing time (2) is also significantly increased compared to the normal mode. When VHS, which is the voltage of the second voltage generator, is applied in the high-sensitivity mode, the operation in the general mode can be removed and the operation in the high-sensitivity mode can be immediately operated, thereby reducing the sensing time. The case (C) of FIG. 13 shows the sensitivity (3) and sensing time (3) when the high-sensitivity mode using the second power supply voltage is operated.

At this time, after setting the second driving voltage VHS, which is the reset voltage through the second switch 420, starting from the state in which the third switch 430 and the sixth switch 320 are operated, the second driving voltage VHS The time until the point where) falls to the reference voltage VREF is checked and the checked first count value is stored. The checked first count value becomes a count value at the time of no-touch, and if the user touches the touch capacitor 210 with a hand even during a high-sensitivity operation, the capacitor capacity of the entire touch sensing unit 200 increases. Accordingly, the time when the second driving voltage VHS falls to the reference voltage VREF when the above-described operation is repeated is shorter than that in the no-touch operation, but the second driving voltage VDD is the reference voltage VREF even when the touch is performed. The time to the point falling to is checked and the checked second count value is stored. The digital processing unit determines whether or not a touch is made through a first count value and a second count value according to the high-sensitivity sensing mode.

Finally, the correction mode is a structure in which each channel has the same value of the second capacitor 220.

14 is a diagram illustrating a circuit connection state in a correction mode according to the present invention, FIG. 15 is a diagram illustrating an actual circuit connection state of FIG. 14, and FIG. 16 is a diagram illustrating an operation timing in a correction mode according to the present invention.

With reference to FIGS. 14 to 16, a description will be made in the correction mode according to the present invention.

In FIG. 14, a part to which a red signal is applied represents a switch that is actually open/closed, and a part to which a black signal is applied represents a switch that exists in an open state so as not to operate. Therefore, description will be made with reference to FIGS. 15 and 16 configured only with an actual operation circuit.

In the correction mode, by using the third capacitor 310 to set all the values of the second capacitor 220 of each channel to be the same, the same sensitivity can be created for each channel. That is, in the correction mode, after checking the capacity of the second capacitor 220 of each channel by performing the offset calibration sensing mode, the value of the second capacitor 220 having the largest capacity is determined as the reference value, and then the third capacitor inside the chip. This is an operation of equally setting the capacitance value of each channel as the reference value using (310). For example, assuming that there are from 1 channel to 3 channels, the value of the second capacitor 220 of the first channel is 30 pF, the value of the second capacitor 220 of the second channel is 20 pF, and the third capacitor of the third channel The (310) value was measured to be 10pF. In this way, if each capacitance value is different, the threshold level setting task must be set differently. Therefore, it is necessary to have the same sensitivity for each channel so that the same reference point level can be set. That is, based on the value of the second capacitor 220 of the first channel having the largest capacitance, 10 pF is compensated for the second channel through the third capacitor 310, and 20 pF is compensated for the third channel. Adjust to 30pF. At this time, the third capacitor 310 is connected to the second capacitor 220 in parallel to add up the capacitance values. To this end, the first switch 410 is closed through the'S1N' signal for each channel and is set to the first driving voltage (VDD). In this case, the third switch 430 is set through the'S2N' signal and the'S2D' signal. And the sixth switch 320 are simultaneously opened, and the fourth switch 440 and the fifth switch 450 are also simultaneously opened through the'S3N' signal and the'S3D' signal. Thereafter, the third switch 430 and the sixth switch 320 and the fourth switch 440 and the fifth switch 450 are alternately opened and closed. That is, after checking the capacity of the second capacitor 220, after setting the capacity of the third capacitor 310, the third switch 430 and the sixth switch 320 are connected through the'S2N' signal and the'S2D' signal. When opening at the same time and closing the fourth switch 440 and the fifth switch 450 through the'S3N' signal and the'S3D' signal at the same time, the second capacitor 220 and the third capacitor 310 are connected in parallel. It is a structure in which capacitance values are summed.

17 is a view showing a switching state in each mode according to the present invention described above.

According to the present invention, a user can set and use a mode as shown in FIG. 17, and when each mode is selected, a signal is set as shown in FIG. 17 to perform a task. S2 vs. S3 represents a non-overlap clock (max 4MHz, applying the divided clock below). SVD & SVS are static control signals, and S1 of High-Sense Sensing needs a little longer time.

According to the present invention described above, high sensitivity detection is possible by shortening the detection time as well as improving the sensitivity.

In addition, since the same capacitance value for each channel can be set and used, the same single THD (Threshold) level can be set to simplify the sensitivity tuning development process, facilitate development, and further shorten the development period.

In the above, even if all the constituent elements constituting the embodiments of the present invention are described as being combined into one or operating in combination, the present invention is not necessarily limited to these embodiments. That is, within the scope of the object of the present invention, all of the constituent elements may be selectively combined and operated in one or more. In addition, terms such as "include", "consist of" or "have" described above mean that the corresponding component may be present unless otherwise stated, excluding other components Rather, it should be interpreted as being able to further include other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined, to which the present invention belongs. Terms generally used, such as terms defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related technology, and are not interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments posted in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

100: voltage accumulating unit 110: first capacitor
200: touch sensing unit 210: touch capacitor
220: second capacitor
300: voltage loss compensation unit 310: third capacitor
320: sixth switch 330: seventh switch
340: 8th switch
400: switching unit 410: first switch
420: second switch 430: third switch
440: fourth switch 450: fifth switch
500: signal comparison unit
600: touch determination signal generator
700: second driving voltage generator

Claims (11)

A voltage accumulating unit including a first capacitor to which a first driving voltage VDD is applied to one terminal;
A touch sensing unit including a touch capacitor that senses a user's touch through one terminal and a second capacitor connected in parallel to the touch capacitor;
Voltage loss compensation unit including a third capacitor that operates in response to a plurality of switching control signals (SVD, SVS) and has a capacity equal to that of the second capacitor by performing a preset capacity setting step ;
Operates in response to a plurality of switching control signals (S1N to S3N, S1D to S3D), and in normal mode, a switching operation between the first driving voltage and the other terminal of the first capacitor, and between the voltage accumulating unit and the touch sensing unit A charge sharing operation is performed between the first capacitor and the second capacitor through a switching operation of, and in the high-sensitivity mode, a switching operation between the second driving voltage VHS and the other terminal of the first capacitor and The loss of the first driving voltage in the first capacitor and the second capacitor generated during the charge distribution operation through a switching operation between the voltage accumulating unit, the touch sensing unit, and the voltage loss compensating unit is calculated. A switching unit for performing a charge compensation operation using a third capacitor and transferring the charge to the other terminal of the first capacitor; And
A signal comparison unit for generating a comparison signal Vcom by comparing the voltage level of the other terminal of the first capacitor with a preset reference voltage VREF, and
A high-sensitivity touch sensor having a voltage level of the first driving voltage higher than that of the second driving voltage. The method of claim 1,
A high-sensitivity touch sensor further comprising a touch determination signal generation unit configured to process the comparison signal Vcom to generate a touch determination signal VOUT reflecting a variation of the comparison signal in a certain range. The method of claim 1,
A high-sensitivity touch sensor further comprising a; digital processing unit for generating the plurality of switching control signals (SVD, SVS, S1N ~ S3N, S1D ~ S3D). The method of claim 1,
And a second driving voltage generator configured to generate the second driving voltage and supply the second driving voltage to the voltage accumulating unit in the high-sensitivity mode. The method of claim 1,
The switching unit,
A first switch opening and closing between the first driving voltage and the (+) input terminal of the signal comparison unit;
A second switch opening and closing between the second driving voltage and the (+) input terminal of the signal comparison unit;
A third switch opening and closing between the touch sensing unit and the ground;
A fourth switch opening and closing between the touch sensing unit and the voltage accumulating unit; And
A fifth switch opening and closing between the voltage loss compensating part and the voltage accumulating part. The method of claim 5,
The voltage loss compensation unit,
The third capacitor;
A sixth switch connected in parallel with the third capacitor;
A seventh switch to which a first driving voltage is connected to the other terminal in the high-sensitivity mode; And
Including an eighth switch to which the other terminal is connected to the ground,
A common terminal connected to one terminal of each of the third capacitor and the sixth switch is connected to the fifth switch,
A high-sensitivity touch sensor in which a common terminal connected to the other terminal of each of the third capacitor and the sixth switch is connected to a common terminal connected to one terminal of each of the seventh switch and the eighth switch. The method of claim 1,
The signal comparison unit,
A high-sensitivity touch sensor in which a (+) input terminal is connected to the voltage accumulating unit and a (-) input terminal is connected to a digital-to-analog converter (DAC) that generates the reference voltage. The method of claim 1,
The second driving voltage generation unit,
A high-sensitivity touch sensor in which a (+) input terminal is composed of a buffer connected to a digital-to-analog converter (DAC) that generates the two driving voltages. The method of claim 1,
In the capacity setting step,
In the normal mode, after storing the count value of the second capacitor, a high-sensitivity touch sensor configured to set a capacitance corresponding to the stored count value to the third capacitor. The method of claim 1,
In correction mode,
A plurality of the touch sensing units and the voltage loss compensation unit are connected,
After grasping the capacity of the second capacitor of each of the touch sensing units, the capacity of the other second capacitor is adjusted according to the value of the second capacitor having the largest capacity by performing a charge compensation operation using the third capacitor. Touch sensor. The method according to any one of claims 1 to 10,
The first capacitor, the second capacitor, and the third capacitor are a high-sensitivity touch sensor comprising a variable capacitor.

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