KR20130136413A - Touch detecting apparatus and method for eliminating noise - Google Patents

Abstract

The present invention relates to a touch detecting device reducing a noise influence. It outputs a level shift value based on a difference of a voltage change occurring by operating a touch sensing unit corresponding to a sensor pad, sequentially calculates touch coordinates and touch area by using the level shift value, and efficiently removes a noise to the sensor pad. [Reference numerals] (210) Touch detecting part;(220) Touch information processing part;(230) Memory;(240) Control part

Description

TOUCH DETECTING APPARATUS AND METHOD FOR ELIMINATING NOISE}

The present invention relates to an apparatus and a method for detecting a touch, and more particularly, to a touch detection apparatus and a method for measuring the area and coordinates of a touch by detecting a touch signal while minimizing noise effects.

The touch screen panel is a device for inputting a command of a user by touching a character or a figure displayed on the screen of the image display device with a finger or other contact means of a person, and is attached and used on the image display device. The touch screen panel converts a contact position that is touched by a human finger or the like into an electrical signal. The electrical signal is used as an input signal.

1 is an exploded top view of an example of a conventional capacitive touch screen panel.

Referring to FIG. 1, the touch screen panel 1 may include a first sensor pattern layer 3, a first insulating layer layer 4, and a second sensor pattern layer sequentially formed on the transparent substrate 2 and the transparent substrate 2. 5) and the second insulating film layer 6 and the metal wiring 7.

The first sensor pattern layer 3 may be connected in the transverse direction on the transparent substrate 2, for example, may be formed in a regular pattern in which a plurality of diamond shapes are connected in a line. The first sensor pattern layer 3 may be formed of a plurality of Y patterns formed such that the first sensor pattern layers 3 positioned in one row having the same Y coordinate are connected to each other. ).

The second sensor pattern layer 5 may be connected along the column direction on the first insulating layer 4, and may be formed in the same diamond shape as the first sensor pattern layer 3, for example. The second sensor pattern layer 5 is connected to the second sensor pattern layers 5 located in one row having the same X coordinate and is connected to the first sensor pattern layer 3 ). ≪ / RTI > In addition, the second sensor pattern layer 5 is connected to the metal wires 7 in units of columns.

The first and second sensor pattern layers 3 and 5 may be made of a transparent conductive material such as indium tin oxide (ITO), and the first insulating layer 4 may be made of a transparent insulating material.

One sensor pattern layer 3, 5 is electrically connected to the driving circuit through the metal wire 7, respectively.

When a finger or a contact means of a person is brought into contact with the touch screen panel 1, a change in capacitance due to the contact position is transmitted to the drive circuit side through the first and second sensor pattern layers 3 and 5 and the metal wiring 7 do.? As the change in capacitance thus transferred is converted into an electrical signal by the X and Y input processing circuits, the contact position is determined.

However, since the touch screen panel 1 has to have an ITO pattern separately on each sensor pattern layer 3 and 5, and an insulating layer 4 between the sensor pattern layers 3 and 5, the thickness increases. .

In addition, since the conventional technology requires touch accumulation by capturing a small change in capacitance generated by touch several times, it is necessary to detect a change in capacitance at a high frequency, which requires complicated computational and statistical processing.

And the prior art requires metal wiring to maintain a low resistance since the capacitance change must be accumulated sufficiently within a predetermined time. This metal wiring thickens the bezel at the edges of the touch screen and creates an additional mask process.

In addition, since touch detection of the conventional touch screen panel 1 is highly dependent on the resistance value and sensitive to noise, there are many difficulties in increasing the touch detection sensitivity. Particularly, the capacitance is not grounded at the time of touch, but the human body reacts to the antenna and a noise signal of an environmental frequency component is input to the touch screen panel 1 as an input. In fact, in an environment using a 50 Hz or 60 Hz home power source, an electric signal applied to the hand tip is interfered with an electric field generated in a home power source, and an input signal of the corresponding frequency is input to the touch screen panel 1. When the human body radiation noise signal flows into the touch screen panel 1, the touch detection value by the touch is greatly changed, and it is impossible to distinguish whether or not the human body radiation noise signal is touched.

Furthermore, the conventional touch screen panel 1 can not calculate an accurate touch area because a touch is detected by using a minute change of the capacitance accumulated several times by a complicated calculation. Thus, it was practically impossible for a user to use the touch area as one means of user input.

SUMMARY OF THE INVENTION An object of the present invention is to provide a touch detection apparatus and a touch detection method capable of minimizing the influence of noise and capable of detecting an accurate touch area and touch coordinates.

According to an aspect of the present invention, there is provided a touch sensing apparatus including: a plurality of sensor pads of a transparent material arranged in a matrix; A driver including a switch and a driving capacitor electrically connected to the plurality of sensor pads, and outputting a voltage change of the sensor pads; A noise voltage for calculating a tracking voltage corresponding to an intermediate value of the output voltage of the driving unit, outputting the non-inverting output voltage of the driving unit larger than the tracking voltage, and inverting and outputting the output voltage of the driving unit smaller than the tracking voltage. government; And a touch information processor that determines whether or not the touch is based on the output from the noise correction unit.

The noise compensator may include a first differential amplifier configured to receive the output voltage and the tracking voltage of the driving unit through a + terminal and a-terminal, respectively, and a second differential that receives the output voltage of the driving unit and the tracking voltage through a-terminal and a + terminal, respectively. It may include an amplifier.

The noise correction unit may calculate the tracking voltage by dividing the maximum value of the output voltage of the driver by subtracting the minimum value of the output voltage of the driver by two.

The noise correction unit may further include a low pass filter, and output the sum of the non-inverted output and the inverted output that have passed through the low pass filter.

The driving unit charges and floats the sensor pad using the switch, and outputs a voltage change in response to an alternating voltage applied to the driving capacitor, and a level shift value based on a difference between the output voltage changes before and after the touch. The apparatus may further include a level shift detector configured to output a.

The touch information processor may calculate a touch area using the level shift value, and calculate touch coordinates using the touch area.

According to a second aspect of the present invention, there is provided a touch detection method, comprising: driving a touch sensing unit corresponding to a sensor pad of a transparent material arranged in a matrix to output a voltage change of the sensor pad; Calculating a tracking voltage corresponding to an intermediate value of the first voltage output in the voltage change output step; Non-inverting and outputting the first voltage that is greater than the tracking voltage, and inverting and outputting the first voltage that is less than the tracking voltage; And determining whether a touch is made based on the non-inverted output and the inverted output.

In the non-inverting and inverting output steps, the first voltage and the tracking voltage are respectively input to the + terminal and the-terminal of the first differential amplifier, and the first voltage and the tracking voltage are respectively connected to the-terminal of the second differential amplifier. It may include the step of input to the + terminal.

The calculating of the tracking voltage may include calculating the tracking voltage by dividing the maximum value of the first voltage by subtracting the minimum value of the first voltage by two.

The method may further include low pass filtering the non-inverted output and the inverted output, and outputting the sum of the filtered non-inverted output and the filtered inverted output.

The step of outputting a voltage change may include outputting a voltage change in response to an alternating voltage applied to the driving capacitor after charging and floating the sensor pad by using a switch electrically connected to the sensor pad. The method may further include outputting a level shift value based on the difference of the output voltage change.

The method may further include calculating a touch area by using the level shift value, and calculating touch coordinates by using the touch area.

An integrated circuit (IC) used in the touch detection apparatus according to the third aspect of the present invention includes a driver including a switch and a driving capacitor electrically connected to a plurality of sensor pads arranged in a matrix, and outputting the voltage change; A noise voltage for calculating a tracking voltage corresponding to an intermediate value of the output voltage of the driving unit, outputting the non-inverting output voltage of the driving unit larger than the tracking voltage, and inverting and outputting the output voltage of the driving unit smaller than the tracking voltage. government; And a touch information processor that determines whether or not the touch is based on the output from the noise correction unit.

As described above, according to the touch detection apparatus according to the embodiment of the present invention, the influence of noise can be minimized, and the touch area and the touch coordinate can be detected accurately.

1 is an exploded plan view of a conventional touch screen panel.
2 is an exploded plan view of a touch detection apparatus according to an embodiment of the present invention.
3 is a block diagram illustrating a configuration of a touch detection apparatus according to an embodiment of the present invention.
4 is a circuit diagram illustrating a touch detector according to an exemplary embodiment of the present invention.
5 is an exemplary waveform diagram of a touch detection unit according to an embodiment of the present invention.
6 is a block diagram of a level shift detection unit according to an embodiment of the present invention.
FIG. 7 is an exemplary circuit diagram of the buffer unit and the amplifier unit shown in FIG. 6.
FIG. 8 is a schematic diagram showing input and output signals by the circuit shown in FIG.
FIG. 9 is a schematic diagram illustrating a filtering process of an output signal of the circuit illustrated in FIG. 7.
10 is a block diagram of a touch information processor according to an embodiment of the present invention.
FIG. 11 is a schematic diagram illustrating a structure of a memory in which information about a sensor pad is stored, according to an exemplary embodiment.
12 is a flowchart illustrating a touch detection method according to an embodiment of the present invention.

The terms used in this specification will be briefly described and the present invention will be described in detail.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

When an element is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, without departing from the spirit or scope of the present invention. In addition, the terms "... unit", "module", etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software. . When a part is "connected" to another part, it includes not only a direct connection but also a connection with another system in the middle.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

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

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

First, a touch detection apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3. FIG.

2 is an exploded plan view of a touch detection apparatus according to an embodiment of the present invention, and FIG. 3 is a block diagram illustrating a configuration of a touch detection apparatus according to an embodiment of the present invention.

Referring to FIGS. 2 and 3, the touch detection apparatus according to the embodiment of the present invention includes a touch panel 100, a driving apparatus 200, and a circuit board 20 connecting the touch panel 100 and the driving apparatus 200.

The touch panel 100 includes a plurality of signal pads 110 formed on a substrate 15 and a plurality of signal pads 120 connected to the sensor pads 110. The substrate 15 may be made of glass or plastic film of transparent material or the like.

For example, the plurality of sensor pads 110 may be rectangular or rhombic, but may be different from each other, or may be polygonal in a uniform shape. The sensor pads 110 may be arranged in a matrix form of adjacent polygons.

Each signal line 120 has one end connected to the sensor pad 110 and the other end extending to the lower edge of the substrate 15. [ The line width of the signal line 120 may be formed to be extremely narrow, such as several micrometers to several tens of micrometers.

The sensor pad 110 and the signal line 120 may be formed of a material such as indium tin oxide (ITO), antimony tin oxide (ATO), indium zinc oxide (IZO), carbon nanotube (CNT), graphene And may be made of a transparent conductive material.

The sensor pad 110 and the signal wiring 120 are formed by, for example, laminating an ITO film on the substrate 15 by a method such as sputtering and then patterning the same using an etching method such as photolithography can do. The substrate 15 may be a transparent film.

On the other hand, the sensor pad 110 and the signal wiring 120 can be directly patterned on the cover glass 10. In this case, since the cover glass 10, the sensor pad 110, and the signal wiring 120 are integrated, the substrate 15 can be omitted.

The driving device 200 for driving the touch panel 100 may be formed on a circuit board 20 such as a printed circuit board or a flexible circuit film, And may be mounted directly on a part thereof. The driving device 200 may include a touch detection unit 210, a touch information processing unit 220, a memory 230, a control unit 240, etc., and may be implemented as one or more integrated circuit (IC) The detection unit 210, the touch information processing unit 220, the memory 230, and the control unit 240 may be separated, or two or more components may be integrated.

The touch detector 210 may include a plurality of switches and a plurality of capacitors connected to the sensor pad 110 and the signal wire 120, and drive circuits for touch detection by receiving a signal from the controller 240. The voltage corresponding to the detection result is output. In addition, the touch detector 210 may include an amplifier and an analog-to-digital converter, and may convert, amplify, or digitize the difference in the voltage change of the sensor pad 110 into the memory 230.

The touch information processor 220 processes the digital voltage stored in the memory 230 to generate necessary information such as whether or not it is touched, a touch area, and touch coordinates.

The control unit 240 controls the touch detection unit 210 and the touch information processing unit 220 and may include a micro control unit (MCU), and may perform predetermined signal processing through the firmware.

The memory 240 stores the digital voltage based on the difference of the voltage change detected from the touch detection unit 210, predetermined data used for touch detection, area calculation, touch coordinate calculation, or data received in real time.

The operation of the touch panel and the touch detection unit will be described in detail with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a circuit diagram illustrating a touch detection unit according to an embodiment of the present invention, and FIG. 5 is an exemplary waveform diagram of a touch detection unit according to an embodiment of the present invention.

Referring to FIG. 4, the touch detector 210 is connected to the sensor pad 110 through a signal wire 120, and performs a switching operation 211, a parasitic capacitor Cp, a driving capacitor Cdrv, The common voltage capacitor Cvcom and the level shift detector 212 are included.

The transistor 211, the parasitic capacitor Cp, the driving capacitor Cdrv, the common voltage capacitor Cvcom, and the level shift detection unit 212 may be grouped one per sensor pad 110 and the signal wire 120. The sensor pad 110, the signal wire 120, the transistor 211, the parasitic capacitor Cp, the driving capacitor Cdrv, and the common voltage capacitor Cvcom are collectively referred to as a "touch sensing unit". . This touch sensing unit is a concept that includes the case where each component is electrically connected by a multiplexer.

Meanwhile, in the exemplary embodiment of the present invention, an electrical characteristic or data value when no touch occurs is referred to as a "non-touch reference value".

For convenience, the same reference numerals are used for capacitors and their capacitances.

The transistor 211 is, for example, a field effect transistor, in which a control signal Vg is applied to a gate, a charging signal Vb is applied to a source, and a drain is applied. ) May be connected to the signal wire 120. Of course, the source may be connected to the signal line 120 and the charging signal Vb may be applied to the drain. The control signal Vg and the charging signal Vb may be controlled by the controller 240, and other devices capable of performing a switching operation may be used instead of the transistor 211.

The parasitic capacitance Cp refers to the capacitance accompanying the sensor pad 110 and is a kind of parasitic capacitance formed by the sensor pad 110, the signal wire 120, and the like. The parasitic capacitance Cp may include any parasitic capacitance generated by the touch detector 210, the touch panel, and the image display device.

The common voltage capacitance Cvcom is a capacitance formed between the common electrode (not shown) and the touch panel 100 of the display device when the touch panel 100 is mounted on a display device (not shown) such as an LCD. to be. A common voltage Vcom such as a square wave is applied to the common electrode by the display device. The common voltage capacitance Cvcom may be included in the parasitic capacitance Cp as a kind of parasitic capacitance. The common voltage capacitance Cvcom may be a parasitic capacitance Cp).

The driving capacitance Cdrv is a capacitance formed in a path for supplying an alternating voltage Vdrv alternately at a predetermined frequency for each sensor pad 110. The alternating voltage Vdrv applied to the driving capacitor Cdrv is preferably a square wave signal. The alternating voltage Vdrv may be a clock signal having the same duty ratio, but different duty ratios. The alternating voltage Vdrv may be provided by a separate alternating voltage generating means, but may also use the common voltage Vcom.

Meanwhile, in FIG. 4, the touch capacitance Ct represents the capacitance formed between the sensor pad 110 and a touch input tool such as a user's finger when the user touches the sensor pad 110.

Referring to FIG. 5, the charging signal Vb and the control signal Vg are applied to the source and the gate of the transistor 211, respectively.

First, a case in which a touch input tool is not touched on the sensor pad 110 will be described. When the control signal Vg applied to the gate of the transistor 211 rises from the low voltage VL to the high voltage VH after the charging signal Vb rises to, for example, 5 V, the transistor 211 is turned on, T1) is started. Accordingly, the sensor pad 110 is charged with the charging signal Vb of 5V, and the output voltage Vo becomes the charging voltage Vb. The parasitic capacitor Cp, the driving capacitor Cdrv, and the common voltage capacitor Cvcom are also charged with the charge voltage Vb. In the charging period T1, since the transistor 211 is turned on, the alternate voltage Vdrv does not affect the output voltage Vo.

Next, when the sensing period T2 starts while the control signal Vg goes from the high voltage VH to the low voltage VL, the transistor 211 is turned off, the touch capacitor Ct, the parasitic capacitor Cp, and the driving. The capacitor Cdrv and the common voltage capacitor Cvcom are isolated in a charged state. In this case, the input terminal of the level shift detector 212 may have a high impedance to stably isolate the charged charge.

The state in which the charges charged in the sensor pad 110 and the like are isolated is called a floating state. At this time, when the alternating voltage Vdrv applied to the driving capacitor Cdrv increases from 0 V to 5 V, for example, the voltage level of the output voltage Vo of the sensor pad 110 is instantaneously raised, The level of the output voltage Vo drops instantaneously. The rise and fall of the voltage level at this time will have different values depending on the connected capacitance. The rising or falling value of the voltage level according to the connected capacitance is also called "kick-back".

When there is no touch on the sensor pad 110, that is, when only the driving capacitor Cdrv and the parasitic capacitor Cp are connected to the sensor pad 110, the output voltage Vo by these capacitors Cdrv and Cp is applied. The voltage variation of ΔVo1 is expressed by Equation 1 below.

[Equation 1]

Where VdrvH and VdrvL are the high level voltage and the low level voltage of the alternating voltage Vdrv, respectively. ΔVo1 of Equation 1 corresponds to an electrical characteristic of the sensor pad 110 in which no touch occurs, and thus may be set to the “non-touch reference value” described above.

Next, a case in which the touch input tool is touched on the sensor pad 110 will be described. When a touch occurs, a touch capacitor Ct is formed between the sensor pad 110 and the touch input tool. Accordingly, the capacitor connected to the sensor pad 110 may include a touch capacitor (in addition to the driving capacitor Cdrv and the parasitic capacitor Cp). Ct) is added. As in the above-described method, the voltage variation ΔVo2 of the sensor pad 110 due to these three capacitors Cdrv, Cp, and Ct in the sensing period T4 through the charging period T3 is expressed by Equation 2 below. Lose.

&Quot; (2) "

Comparing [Equation 1] and [Equation 2], since the touch capacitance (Ct) is added to the denominator item of [Equation 2], the voltage fluctuation (ΔVo2) when there is a touch, the touch is It is small compared to the voltage fluctuation ΔVo1 in the absence, and the difference depends on the touch capacitance Ct. Thus, the difference (DELTA) Vo1-(DELTA) Vo2 of the voltage fluctuation (DELTA) Vo before and behind a touch is called "level shift." In the present specification, the "level shift" may mean a digital value of the voltage variation ([Delta] Vo) difference.

The capacitance C of the capacitor is C = ε * A / d, which is proportional to the area A of the electrode and inversely proportional to the distance d between the electrodes (ε is a dielectric constant). Therefore, as the touch area increases, the touch capacitance Ct increases. 5, when the variation of the alternating voltage Vdrv applied to the driving capacitor Cdrv occurs in the sensing periods T2 and T4 during which the transistor 211 is turned off, A voltage change occurs. By using such a relationship, whether or not the touch and the touch area may be calculated by using the difference ΔVo1-ΔVo2 of the voltage variation ΔVo of the output voltage Vo before and after the touch.

Referring back to FIG. 4, the level shift detector 212 detects a level shift generated by an alternating voltage Vdrv in a floating state. Specifically, the level shift detection unit 212 detects a variation (? Vo1) of the output voltage Vo at the sensor pad 110 at the time of occurrence of a non-touch and a variation (? Vo1) of the output voltage Vo at the sensor pad 110 ? Vo2) can be measured to detect whether a level shift has occurred. That is, the potential of the sensor pad 110 is raised or lowered by the applied alternating voltage Vdrv. The voltage level fluctuation when the touch occurs is smaller than the voltage level fluctuation when the touch is not generated. Therefore, the level shift detecting section 212 detects the level shift by comparing the level of the output voltage Vo immediately after the rise of the alternating voltage Vdrv in the floating state. In this case, if the level shift value is not 0, a touch has occurred, and thus the level shift value can be used as a touch signal. On the other hand, when the alternating voltage (Vdrv) falls first in the floating state, the level shift may be detected by comparing the output voltage (Vo) level immediately after the falling.

The level shift detection unit 212 will now be described in more detail.

6 is a block diagram of a level shift detection unit according to an embodiment of the present invention.

Referring to FIG. 6, the level shift detection unit 212 according to the present embodiment includes an amplifier 2121, a buffer unit 2122, a reference value providing unit 2123, an analog-to-digital converter (ADC) 2124, and a level. A shift output section 2125, a level shift correcting section 2126, and a noise correcting section 2127 are included. The level shift detector 212 may omit at least one of these elements as necessary. In addition, the level shift detection unit 212 may include a voltage to frequency converter (VFC), a flip-flop, a latch, and a transistor. (Transistor), a thin film transistor (Thin Film Transistor), it may be configured by combining at least one of a comparator.

The amplifying unit 2121 amplifies the output voltage Vo of the touch sensing unit. The amplification section 2121 may be a single input amplifier or a differential amplifier. In case of a differential amplifier, the two inputs of the differential amplifier may be the output voltage Vo of the touch sensing unit and the reference voltage Vr of the touch reference device, and the amplification unit 2121 may output the difference between the two voltages Vo and Vr Can be amplified and output.

The buffer unit 2122 buffers the output voltage Vo and may perform the amplifying operation of the amplifying unit 2121. [

As described above, the touch sensing unit includes the sensor pad 110, the signal wiring 120, the transistor 212, the driving capacitor Cdrv, and the parasitic capacitor Cp shown in FIG. 4, And further includes a touch capacitor Ct.

The voltage difference (? V = Vr - Vo) between the output voltage Vo of the touch sensing unit and the reference voltage Vr corresponding to the non-touch reference value means a voltage difference when the alternating voltage Vdrv rises or falls, This voltage difference? V is equal to the analog value of the level shift, and can be expressed by the following equation (3).

&Quot; (3) "

Where ΔVr = Vr-Vb and ΔVo = Vo-Vb.

When the touch capacitance Ct is 0, that is, when the non-touch voltage difference? V is 0, and as the touch capacitance Ct is increased, the voltage difference? V also increases. Since the touch capacitance Ct is proportional to the touch area A and inversely proportional to the distance d between the touch pad 110 and the touch pad, that is, Ct = epsilon A / d, (A) and the touch capacitance (Ct) are linearly proportional. Therefore, it can be understood that the larger the voltage difference? V, the larger the touch area A is.

On the other hand, the reference value providing portion 2123 can provide the reference voltage Vr to the amplifying portion 2121. The reference value providing unit 2123 stores the digital value of the reference voltage Vr in the memory 230 for each sensor pad 110 and reads the digital value and provides the analog reference voltage Vr to the differential amplifier through the digital- can do. When the amplifying unit 2121 is a single input amplifier, the reference value providing unit 2123 may include a subtracting circuit and may output a value obtained by subtracting the output value of the amplifying unit 2121 from the reference voltage Vr . Or the reference value providing portion 2123 may provide the reference voltage Vr directly to the analog-to-digital converting portion 2124. [

Next, the noise correction unit 2127 will be described in more detail with reference to FIGS. 7 to 9.

FIG. 7 is an exemplary circuit diagram of the buffer unit 2122 and the noise correction unit 2127 shown in FIG. 6, FIG. 8 is a schematic diagram showing input and output signals by the circuit shown in FIG. 7, and FIG. 9 is FIG. 7. It is a schematic diagram which shows the filtering process of the output signal of the circuit shown in the figure.

The buffer unit 2122 holds the amplified voltage Vod to output the output voltage Vob so that the amplified voltage Vod output from the amplification unit 2121 does not fluctuate, ) Buffer.

The noise corrector 2127 removes a noise component introduced by the touch contact means from the output voltage Vob of the buffer unit 2122 and corrects the output voltage Vob of the buffer unit 2122.

Referring to FIG. 7, the noise corrector 2127 includes two differential amplifiers 2127a and 2127b. The output voltage Vob of the buffer unit 2122 is input to the positive terminal of the differential amplifier 2127a and the negative terminal of the differential amplifier 2127b and the tracking voltage Vtr is input to the negative terminal of the differential amplifier 2127a and the negative terminal of the differential amplifier 2127b. Is input to the + terminal of the second comparator 2127b. Therefore, the differential amplifier 2127a amplifies the portion of the output voltage Vob of the buffer portion 2122 that is larger than the tracking voltage Vtr and outputs the voltage value Vop, and the differential amplifier 2127b amplifies the output voltage Vob And outputs the voltage value (Vom).

As illustrated in FIG. 8, the noise correction unit 2127 has a tracking voltage Vtr such that the amplitude of the output signal Vo of the differential amplifier 2127a and the output signal Vom of the differential amplifier 2127b are substantially the same. Set. For example, a value obtained by dividing the value obtained by subtracting the minimum value from the maximum value of the output signal Vob of the buffer unit 2122 by 2 can be set as the tracking voltage Vtr value. By setting the tracking voltage Vtr as described above, the magnitudes of the + peak value and the − peak value of the output voltage Vob of the buffer unit 2122 are substantially the same based on the tracking voltage Vtr.

The noise corrector 2127 may further include an analog or digital lowpass filter and may be configured to receive the output signal Vop of the differential amplifier 2127a and the output signal Vom of the differential amplifier 2127b, And adds the signals (Vop ', Vom'). Then, as shown in FIG. 9, an output signal Vop '+ Vom' having a flat waveform similar to passing through the rectifier is obtained, which corresponds to a noise corrected level shift value.

4, when a touch input means such as a finger touches the sensor pad 110, human body radiation noise flows through the sensor pad 110, which affects the output voltage Vo, making it difficult to determine whether or not the touch is input. If the output voltage Vob of the buffer unit 2122 including the human body radiation noise is used as it is, as shown in the first waveform of FIG. It is also difficult to calculate the exact touch area. However, by inverting the lower part of the output voltage Vob of the buffer unit 2122 based on the tracking voltage Vtr and summing it with the upper part, the influence on noise can be eliminated and the accurate touch area can be calculated.

On the other hand, the amplifier 2121 of the level shift detector 212 according to the embodiment of the present invention may be omitted. In this case, the output voltage Vo of the sensor pad 110 is directly input to the buffer unit 2122, and the output voltage of the sensor pad 110 using the differential amplifiers 2127a and 2127b of the noise correction unit 2127. Vo) can be amplified. The touch reference device can also amplify the reference voltage Vr of the touch reference device via the noise corrector 2127 and output the level shift voltage Vr using the amplified output voltage Vo and the amplified reference voltage Vr. Can be calculated.

The analog-to-digital converter 2124 can convert the analog signal used in the noise corrector 2127 into a digital signal and output it. If necessary, the output signals (Vop, Vom) of the differential amplifier (2127a) and the differential amplifier (2127b) may be converted, or the sum signal (Vop + Vom) thereof may be converted, or the signal after the filtering process may be digitally converted. have. The analog-to-digital converter 2124 may divide the output signal of the noise corrector 2127 into four sections, and may assign a digital value of 2 bits in order of magnitude to each section. However, the digital value of 2 bits is only an example, and other bits such as 3 bits, 4 bits, 8 bits, and 10 bits are also possible.

The value obtained by digitally converting the final output signal (Vop '+ Vom') of the noise corrector 2127 is referred to as a "level shift value ".

The level shift output section 2125 receives the level shift value corresponding to the voltage difference? V before and after the touch from the analog-to-digital conversion section 2124 and outputs it. In the case where the analog-to-digital conversion section 2124 directly outputs the level shift value, the analog-to-digital conversion section 2124 includes the function of the level shift output section 2125.

Since the touch capacitance Ct is located in the denominator in Equation (3), the level shift value before and after touching increases as the touch capacitance Ct increases, but has a complete linearity Do not. The level shift correction unit 2126 corrects the nonlinearity of the touch sensing unit and outputs the output value of the analog-to-digital conversion unit 2124 or the output value of the level shift output unit 2125 Correct the output value.

As an example, the level shift correction unit 2126 may include a table in which the level shift value and the touch capacitance Ct value correspond one-to-one, and the touch capacitance Ct corresponding to the level shift value is extracted .

As another example, the level shift correction unit 2126 may divide the level shift value by intervals, generate a linear function in each interval, and match the output value of the generated linear function with respect to each voltage difference? V.

As another method, linearity can be imparted between the voltage difference ΔV and the touch area A by applying a predetermined weight to the output of each voltage difference ΔV.

On the other hand, even if the relationship between the voltage difference ΔV and the touch area A is not a perfectly linear proportion, if the slope is sufficiently gentle to provide sufficient accuracy for calculating the area, it is treated as being substantially linear proportional, and the voltage is not treated without special correction. The difference ΔV can be used to calculate the touch area A. In this case, the level shift correction unit 2126 may be omitted from the level shift detection unit 212.

The level shift value or its correction value is stored in the memory 230.

As described above, according to the level shift detector 212 according to the embodiment of the present invention, it is possible to appropriately compensate for the noise input generated from the human body contact, and the level shift before and after the touch and the touch area A are linearly proportional . Therefore, using such a linear proportional relationship, the touch detection apparatus according to the embodiment of the present invention can detect a very accurate touch area and touch coordinates.

Next, an operation of detecting the touch area and the touch coordinates by the touch detection apparatus according to the exemplary embodiment of the present invention will be described in detail with reference to FIGS. 10 to 12.

10 is a block diagram of a touch information processor according to an embodiment of the present invention. FIG. 11 is a schematic diagram illustrating a structure of a memory in which information about a sensor pad according to an embodiment of the present invention is stored. A flowchart illustrating a touch detection method according to an embodiment of the present invention.

As illustrated in FIG. 10, the touch information processor 220 according to an exemplary embodiment of the present invention may include a touch sensor pad detector 221 for detecting a sensor pad on which a touch occurs, and a touch for calculating a touch area of a touch pad on which a touch occurs. The area calculator 222 includes a touch coordinate calculator 223 that calculates touch coordinates using the calculated touch area. The touch information processing unit 220 may be implemented in software or firmware and may be operated in association with the MCU.

The memory 230 shown in FIG. 11 may include, for example, a plurality of memory elements having addresses corresponding to the sensor pads 110, and each memory element may be amplified, digitized, and The corrected level shift value ΔVD can be stored.

As described above, the level shift value DELTA VD stored in the memory 230 is linearly proportional to the touch area occupied by the sensor pad 110. [ Therefore, this level shift value DELTA VD can be handled as the same as the touched digital area value. The level shift value ΔVD may have four values of 00, 01, 10, and 11, for example, when digitized to 2 bits. Here, 00 means no touch, and 11 means that the entire sensor pad 110 is touched and covered. As described above, the magnitude of the level shift value ΔVD corresponds to the magnitude of the touch area for one sensor pad 110.

11, memory elements M11 to M54 are illustrated, and for convenience of explanation, it is assumed that they are disposed at the same positions as the sensor pads arranged in a 4 × 5 form. 00 is stored in the memory elements M13, M14, M23, M24, M31, M32, M33, M41, M42, M43, M51, M52, M53 and M54 corresponding to the sensor pads M12, M21, M22, M34, and M44 corresponding to the sensor pads corresponding to the sensor area, the digital value corresponding to the contact area will be stored.

The touch information processing unit 220 reads the touched digital area values from each of the sensor pads from the memory 230 to determine a contact area and a contact position. For example, the center of gravity of the entire touch area of the sensor pad other than 00 can be calculated as touch coordinates.

In addition, when the non-00 sensor pads are grouped into a plurality of groups, the touch information processing unit 220 can also detect the area and coordinates of the multi-touch. For example, as illustrated in FIG. 11, the first touch may be detected over M11, M12, M21, and M22, and the second touch may be detected over M34 and M44.

Referring to FIG. 12, the touch detection method according to the present embodiment first detects a common voltage Vcom cycle of a display device on which the touch detection device is mounted (S100). The touch detection apparatus may include a separate circuit for detecting the common voltage Vcom period. Alternatively, the touch detection apparatus may provide information about the common voltage Vcom such as the period and the rising (or falling) edge point of the common voltage Vcom. It may be provided from a display device.

The touch detection apparatus avoids the rising edge and the falling edge of the common voltage Vcom and controls the timing of the alternating voltage Vdrv so that the rising edge and the falling edge of the alternating voltage Vdrv are generated in the high voltage state . In this way, it is possible to prevent the level shift caused by the alternating voltage Vdrv from being distorted by the common voltage Vcom.

As described above, the common voltage Vcom can be used as the alternating voltage Vdrv for touch detection. In this case, the rising edge and the falling edge of the common voltage Vcom are set to the turn-off state VL) state, the timing of the control signal Vg can be controlled. The touch detection apparatus raises the control signal Vg from the low voltage VL to the high voltage VH while the charge signal Vb is raised, thereby turning on the transistor 211 to charge the sensor pad 110 with the charge signal Vb. Charge to (S110).

Then, the touch detection apparatus lowers the control signal Vg from the high voltage VH to the low voltage VL with respect to each touch sensing unit, thereby bringing the sensor pad 110 into a floating state. The common voltage Vcom or the alternating voltage Vdrv is raised from the low voltage VdrvL to the high voltage VdrvH and the output voltage Vo of the sensor pad 110 is measured, And then scans in a predetermined order (S120). Conversely, the scan can be performed by lowering the common voltage Vcom or the alternating voltage Vdrv from the high voltage VdrvH to the high voltage VdrvL and measuring the output voltage Vo of the sensor pad 110.

The touch detection apparatus detects the level shift value DELTA VD by amplifying the output voltage Vo and analog-to-digital converting the variation (? Vo) of the output voltage (S130). The level shift value DELTA VD is a value corresponding to the difference of the voltage change amount? Vo before and after the touch. The detected level shift value DELTA VD is recorded in the memory 230 corresponding to each sensor pad.

It is determined whether the level shift value ΔVD is 0 (S140), and when it is 0, steps S110 to S130 are repeated (S140). That is, if the level shift value DELTA VD is 0, since the sensor pad does not generate a touch, the level shift value DELTA VD is detected until a touch occurs.

If the level shift value DELTA VD is not 0, the sensor pad group consisting of adjacent sensor pads whose level shift value DELTA VD is not 0 is extracted (S150). According to an embodiment of the present invention, since the sensor pads 110 are each implemented in an isolated matrix form, the sensor pads 110 provide a multi-touch sensing function. Accordingly, when multi-touch is generated, the touch pads are grouped to calculate touch areas and coordinates.

Then, the area of the touch area is calculated based on the level shift value DELTA VD of the touched sensor pad group (S160). As described above, since the level shift value DELTA VD and the touch area are mutually proportional, the touch area can be calculated by summing the level shift value DELTA VD in the sensor pad group.

Next, the coordinates of the touch area are calculated from the calculated area of the touch area (S170). In the touch panel 100 according to the exemplary embodiment of the present invention, the sensor pad 110 has a polygonal shape with a uniform size, and is arranged in a matrix form. Therefore, since each of the sensor pads 110 covers the display device with a predetermined area and address, the occupied area of the sensor pads 110 can be matched with the coordinates of the image display device.

When information on the touch occupation area is calculated for each sensor pad 110 from the touch area calculated in step S170, the touch area distribution of the X axis and the Y axis of the sensor pad group touched on the sensor pad matrix can be obtained have. If the area center points of the X axis and the Y axis are obtained based on the area distribution, touch coordinates corresponding to the center point of the touch area of the touched sensor pad group can be calculated. By using the structure of the touch panel 100 and the calculated touch area, touch coordinates can be calculated very accurately.

By repeating these steps (S110 to S170), it is possible to continuously detect whether or not the touch is performed, the touch area, and the touch coordinates.

It is to be understood that the foregoing description of the disclosure is for the purpose of illustration and that those skilled in the art will readily appreciate that other embodiments may be readily devised without departing from the spirit or essential characteristics of the disclosure will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

It is to be understood that the scope of the present invention is defined by the appended claims rather than the foregoing description and that all changes or modifications derived from the meaning and scope of the claims and equivalents thereof are included in the scope of the present invention .

10: cover glass, 15: substrate,
20: circuit board, 100: touch panel,
110: sensor pad, 120: signal wiring,
200: drive unit, 210: touch detection unit,
212: transistor, 212: level shift detector,
2121: amplification unit, 2122: buffer unit,
2123: reference value providing unit, 2124: analog-to-digital conversion unit,
2125: level shift output unit, 2126: level shift correction unit
2127: noise correction unit, 220: touch information processing unit,
221: touch sensor pad detection unit,
222: Touch Area Calculation Unit, 223: Touch Coordinate Calculation Unit,
230: memory, 240: control unit

Claims (16)

A plurality of sensor pads of transparent material arranged in a matrix form;
A driver including a switch and a driving capacitor electrically connected to the plurality of sensor pads, and outputting a voltage change of the sensor pads;
A noise voltage for calculating a tracking voltage corresponding to an intermediate value of the output voltage of the driving unit, outputting the non-inverting output voltage of the driving unit larger than the tracking voltage, and inverting and outputting the output voltage of the driving unit smaller than the tracking voltage. government; And
A touch information processor that determines whether a touch is based on an output from the noise correction unit
Touch detection device comprising a. The method of claim 1,
The noise compensator may include a first differential amplifier configured to receive the output voltage and the tracking voltage of the driving unit through a + terminal and a-terminal, respectively, and a second differential that receives the output voltage of the driving unit and the tracking voltage through a-terminal and a + terminal, respectively. Touch detection device comprising an amplifier. 3. The method of claim 2,
And the noise correcting unit calculates the tracking voltage by dividing the maximum value of the output voltage of the driver by subtracting the minimum value of the output voltage of the driver by two. The method of claim 1,
The noise correction unit further includes a low pass filter, the touch detection device for outputting the sum of the non-inverted output and the inverted output passing through the low pass filter. The method of claim 1,
The driving unit charges and floats the sensor pad using the switch and outputs a voltage change in response to an alternating voltage applied to the driving capacitor.
And a level shift detector for outputting a level shift value based on the difference in the output voltage change before and after the touch. The method of claim 5,
And the touch information processing unit calculates a touch area using the level shift value, and calculates touch coordinates using the touch area. Outputting a voltage change of the sensor pad by driving a touch sensing unit corresponding to the sensor pad of a transparent material arranged in a matrix form;
Calculating a tracking voltage corresponding to an intermediate value of the first voltage output in the voltage change output step;
Non-inverting and outputting the first voltage that is greater than the tracking voltage, and inverting and outputting the first voltage that is less than the tracking voltage; And
Determining whether a touch is made based on the non-inverted output and the inverted output
And a touch detection method. The method of claim 7, wherein
In the non-inverting and inverting output steps, the first voltage and the tracking voltage are respectively input to the + terminal and the-terminal of the first differential amplifier, and the first voltage and the tracking voltage are respectively connected to the-terminal of the second differential amplifier. Touch detection method comprising the step of input to the + terminal. 9. The method of claim 8,
The tracking voltage calculating step includes calculating the tracking voltage by dividing the maximum value of the first voltage by subtracting the minimum value of the first voltage by two. The method of claim 7, wherein
And performing low pass filtering on the non-inverted output and the inverted output, and outputting a sum of the filtered non-inverted output and the filtered inverted output. The method of claim 7, wherein
The step of outputting a voltage change includes charging and floating the sensor pad using a switch electrically connected to the sensor pad and outputting a voltage change in response to an alternating voltage applied to the driving capacitor,
Outputting a level shift value based on a difference in the output voltage change before and after the touch;
Touch detection method. 12. The method of claim 11,
Calculating a touch area by using the level shift value, and calculating touch coordinates by using the touch area. In an integrated circuit (IC) used in a touch detection device,
A driver including a switch and a driving capacitor electrically connected to the plurality of sensor pads arranged in a matrix form, and outputting the voltage change;
A noise voltage for calculating a tracking voltage corresponding to an intermediate value of the output voltage of the driving unit, outputting the non-inverting output voltage of the driving unit larger than the tracking voltage, and inverting and outputting the output voltage of the driving unit smaller than the tracking voltage. government; And
A touch information processor that determines whether a touch is based on an output from the noise correction unit
Integrated circuit comprising a. The method of claim 13,
The noise compensator may include a first differential amplifier configured to receive the output voltage and the tracking voltage of the driving unit through a + terminal and a-terminal, respectively, and a second differential that receives the output voltage of the driving unit and the tracking voltage through a-terminal and a + terminal, respectively. Integrated circuit comprising an amplifier. 15. The method of claim 14,
And the noise correction unit calculates the tracking voltage by dividing the tracking voltage by 2 minus the maximum value of the output voltage of the driving unit minus the minimum value of the output voltage of the driving unit. The method of claim 13,
The noise correction unit further includes a low pass filter, and outputs the sum of the non-inverted output and the inverted output passing through the low pass filter.

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