KR101209114B1 - Apparatus for sensing charge of touch panel with removing low frequency noise - Google Patents

Abstract

PURPOSE: A charge sensing apparatus of touch panel that removed low frequency noise is provided to guarantee sufficient sensitivity to catch a small change of charge and minimizing the noise by reducing the low frequency noise. CONSTITUTION: A charge sensing apparatus(100) of touch panel comprises a signal transmitting unit(110), a capacitance sensor(120), a signal receiver(130), a noise eliminator(140), and an AD(Analog to Digital) converter(150). The signal transmitting unit outputs by generating sensing signal including the information about the sampling point. The capacitance sensor comprises an input terminal and an output terminal. The input terminal receives the sensing signal. The output outputs the first charge and the second charge repetitively in order, when the conductor touches the touch panel by responding to the received sensing signal. The signal receiver outputs the first cumulated voltage and the second cumulated voltage by sampling the first modified charge and the second modified charge in N times respectively, and controlling gain. The noise eliminator calculates the difference of the first cumulated voltage and the second cumulated voltage, after receiving the first cumulate voltage and the second cumulate voltage sequentially. The noise eliminator outputs the low frequency noise removed voltage difference which is generated by touching the conductor on the touch panel. The AD converter outputs the voltage difference transmitted to digital signal. [Reference numerals] (110) Signal transmitting unit; (131) Sampling unit; (133) First charge accumulation unit; (134) Second charge accumulation unit; (135) Gain controller; (143) CDS controller; (145) CDS unit

Description

Apparatus for sensing charge of touch panel with removing low frequency noise}

The present invention relates to a device for detecting a charge amount of a touch panel, and in particular, attenuates low-frequency noise generated by a touch of a panel and a conductor as well as noise included in a signal itself, thereby minimizing noise and ensuring sufficient sensitivity even for small charge amount changes. The present invention relates to a device for sensing a charge amount of a touch panel.

In general, a touch panel (for example, a touch key, a touch screen, etc.) detects whether a conductor (for example, a finger, a pen, etc.) is touched and outputs a digital signal to detect the amount of charge of the touch panel for use in an application. Use a device to

In order to sense the amount of charge in the touch panel, the method of sensing the amount of charge in the capacitance sensor on the touch panel side is to detect a change in the amount of charge generated by the influence of a conductor that touches, and is currently used in capacitance sensors used in various applications including portable devices. The amount of charge change is not large. The change in the charge amount is proportional to the change in the capacitance value of the capacitance sensor, and the change generally has a capacitance value of several tens fF to several hundred fF.

To amplify the signal sensed by the capacitance sensor in order to increase the change in the amount of charge due to the touch of the conductor, it is generally used, but this method is contrary to the current development trend of low voltage and low power, and is caused by the use of additional external devices. It causes problems in cost increase and battery use applications. In addition, noise is present in the signal sensed by the capacitance sensor, and when the touch panel and the conductor touch, power noise is generated by a power applied to the system including the touch panel, and conductor noise is generated between the touch panel and the conductor. do. However, in the case of simply amplifying the sensed signal, the noise is also amplified by amplifying the noise at the same ratio as described above. In addition, when the power supply noise and the conductor noise are not removed, an inaccuracy and shaking of touch coordinates may occur during touch recognition.

The problem to be solved by the present invention is to reduce the low-frequency noise generated by the touch of the panel and the conductor as well as the noise contained in the signal itself to minimize the noise while ensuring a sufficient sensitivity even for small changes in the charge amount of the touch panel To provide.

According to an aspect of the present invention, there is provided a device for detecting a charge amount of a touch panel, the signal transmitting unit generating and outputting a sensing signal including information on a sampling time point, an input terminal for receiving the sensing signal, and A capacitance sensor comprising an output terminal that sequentially outputs a first charge amount having a sensed positive value and a second charge amount having a negative value when the conductor touches the touch panel in response to the received sensing signal, the capacitance A signal receiver configured to sample and accumulate the first charge amount and the second charge amount output from a sensor n times (n is a natural number), and adjust a gain to output a first accumulated voltage and a second accumulated voltage; Receiving a first cumulative voltage and the second cumulative voltage sequentially and calculating a voltage difference between the first cumulative voltage and the second cumulative voltage; The touch panel may include a noise removing unit configured to output the voltage difference from which the low frequency noise generated when the conductor is touched, and an analog to digital (AD) converter to convert the voltage difference into a digital signal and output the digital signal.

When the conductor touches the touch panel, the low frequency noise may include power source noise generated by power applied to a system including the touch panel, and conductor noise generated between the touch panel and the conductor. .

Each of the first cumulative voltage and the second cumulative voltage includes a noise voltage corresponding to the power source noise and the conductor noise, and the voltage difference between the first cumulative voltage and the second cumulative voltage is the first cumulative voltage and the second cumulative voltage. It may be a voltage difference between a voltage corresponding to the first charge amount and the voltage corresponding to the second charge amount in which the noise voltage is canceled by a subtraction operation of two cumulative voltages.

The sensing signal is a signal in which the first logic state and the second logic state are repeated in a section in which the signal receiver samples and accumulates the first and second charges, and the capacitance sensor indicates that the sensing signal is in the first logic state. The first charge amount may be output at a time point when the state changes to the second logic state, and the second charge amount may be output at a time point when the sensing signal is changed from the second logic state to the first logic state.

The noise removing unit performs a correlated double sampling of the first cumulative voltage and the second cumulative voltage in response to the CDS control unit and the CDS control unit to generate a plurality of CDS control signals in response to the digital signal. And a CDS unit configured to output a voltage difference between the first accumulated voltage and the second accumulated voltage, from which the low frequency noise is removed and the gain is adjusted.

The CDS unit selector for sequentially outputting the first and second cumulative voltage output from the signal receiving unit in response to the first and second selection signal of the CDS control signals, one end is connected to the output terminal of the selection unit A CDS operation including a first CDS capacitor, an input terminal connected to the other end of the first CDS capacitor, a ground voltage input terminal connected to a ground voltage source, and an output terminal outputting a voltage difference between the first accumulated voltage and the second accumulated voltage An input terminal of the CDS operational amplifier in response to a CDS initialization signal among the CDS control signals in a section other than a section for outputting the voltage difference from the amplifier, the CDS operational amplifier and the digital signal output from the AD converter; A CDS initialization switching unit for connecting the output terminal to initialize the voltage difference, and between the input terminal and the output terminal of the CDS operational amplifier. A plurality of second CDS capacitors connected to or disconnected from an input terminal and an output terminal of the CDS operational amplifier in response to a corresponding CDS gain control signal among the CDS control signals; CDS gain control switching unit may be provided.

The CDS controller decreases the number of the second CDS capacitors connected between an input terminal and an output terminal of the CDS operational amplifier when the voltage difference between the first cumulative voltage and the second cumulative voltage is amplified, and the first cumulative voltage is amplified. When the voltage difference between the voltage and the second cumulative voltage is to be attenuated, the CDS gain control signals may be generated to increase the number of the second CDS capacitors connected between an input terminal and an output terminal of the CDS operational amplifier.

The CDS unit may further include a holding unit which connects or blocks the other end of the first CDS capacitor and the input end of the CDS operational amplifier in response to a holding signal among the CDS control signals.

The signal receiver is configured to sample the first charge amount and the second charge amount output from the capacitance sensor n times in response to sampling control signals including information about a sampling frequency, and the digital output from the AD converter. A gain controller generating and outputting a plurality of gain control signals using a signal; a first accumulating the n-th sampled charge amounts in response to the gain control signals, and adjusting a gain to output the first accumulated voltage; And a second charge amount accumulator configured to accumulate the n-times sampled second charge amounts in response to the gain control signals and adjust gain to output the second accumulated voltage.

According to an embodiment of the present invention, an apparatus for detecting a charge amount of a touch panel cancels low frequency noise such as power supply noise and conductor noise generated by a touch of a panel and a conductor, and amplifies the amount of charge according to a touch state of the touch panel. By averaging without noise, it minimizes noise by attenuating noise included in a signal, thereby improving signal-to-noise ratio (SNR) and ensuring sufficient sensitivity even with small charge changes. There is an advantage.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.
1 is a block diagram of an apparatus for detecting a charge amount of a touch panel according to an exemplary embodiment of the inventive concept.
FIG. 2 is a circuit diagram illustrating an embodiment of an apparatus for detecting a charge amount of a touch panel of FIG. 1.
3 is a waveform diagram of signals used in the amount of charge sensing device of the touch panel of FIG. 2.
4 is a circuit diagram schematically illustrating a first charge amount accumulating part, a second charge amount accumulating part, and a CDS part of FIG. 2.
FIG. 5 is a diagram for describing a change in charge amount according to a touch state of a conductor in accordance with one embodiment of the capacitance sensor of FIG. 1.
FIG. 6 is a view for explaining a change in charge amount according to a touch state of a conductor in accordance with another embodiment of the capacitance sensor of FIG. 1.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

1 is a block diagram of an apparatus 100 for detecting a charge amount of a touch panel according to an embodiment of the inventive concept.

Referring to FIG. 1, an apparatus 100 for detecting a charge amount of a touch panel may include a signal transmitter 110, a capacitance sensor 120, a signal receiver 130, a noise remover 140, and an analog to digital converter (AD). 150).

The signal transmitter 110 may generate and output a sensing signal SEN including information about a sampling time point. The sensing signal SEN may be a sine wave signal in which the first logic state and the second logic state are repeated, or a signal in which the first logic state and the second logic state are repeated in a section in which the signal receiver 130 samples and accumulates charge amounts. The information on the sampling time point may be information on a time point at which a logic state of the sensing signal SEN is changed. For example, the sampling time may be a time when the sensing signal SEN is changed from the first logic state to the second logic state and when the sensing signal SEN is changed from the second logic state to the first logic state. In the following description, it is assumed that the first logic state is a logic low state and the second logic state is a logic high state. However, the present invention is not limited to this case and conversely, the first logic state may be a logic high state and the second logic state may be a logic low state. An embodiment of the configuration of the signal transmitter 110 will be described in more detail with reference to FIG. 2.

The capacitance sensor 120 receives an input terminal IN for receiving the sensing signal SEN output from the signal transmitter 110 and a first charge amount S and a second charge amount sensed in response to the received sensing signal SEN. It may include an output terminal (OUT) for outputting (-S). That is, when the conductor touches the touch panel, the capacitance sensor 120 may generate the first charge amount S having a positive value and the second charge amount −S having a negative value in response to the sensing signal SEN. You can print For example, the capacitance sensor 120 may be a mutual capacitance sensor that senses and outputs an amount of charge between the input terminal IN and the output terminal OUT. The touch panel may include all of a touch key and a touch screen capable of detecting a touch of a conductor (for example, a finger or a pen), and hereinafter referred to as “touch” is output from the capacitance sensor 120. This means that the conductor is in close or direct contact with the touch panel so that the amount of charge is changed.

 The first charge amount S and the second charge amount −S may include a low frequency noise component. For example, when the conductor touches the touch panel, capacitance is generated between the touch panel and the conductor, causing unwanted low frequency noise (N) (eg, conductor noise) due to the voltage of the conductor. Done. Since the conductor noise has the same sign and the same magnitude and is added to the first charge amount S and the second charge amount −S, the first charge amount output from the capacitance sensor 120 substantially reduces the charge amount of S + N. In addition, the second charge amount output from the capacitance sensor 120 may have a charge amount of -S + N.

The capacitance sensor 120 outputs the first charge amount S at the time when the sensing signal SEN is changed from the first logic state to the second logic state, and the sensing signal SEN is in the first logic state in the second logic state. The second charge amount (-S) may be output at the point of time changed to. However, the present invention is not limited to this case, and the second charge amount S is output at the time when the sensing signal SEN is changed from the first logic state to the second logic state, and the sensing signal SEN is the second. The first charge amount S may be output at the time when the logic state is changed to the first logic state. Hereinafter, for convenience, S + N in which the conductor noise N is added to the first charge amount S output from the capacitance sensor 120 is referred to as a first charge amount, and the second charge amount -S output from the capacitance sensor 120 is referred to as a first charge amount. The sum of the conductor noises N and -S + N is referred to as the second charge amount.

The signal receiver 130 samples and accumulates n times (n is a natural number) of the first charge amount S + N and the second charge amount (-S + N) output from the capacitance sensor 120, and accumulates gain. The first cumulative voltage V1 and the second cumulative voltage V2 may be output by adjusting. That is, the first cumulative voltage V1 is accumulated by sampling the first charge amount S + N n times and adjusting the gain, thereby being included in the first charge amount S sensed by the capacitance sensor 120 in addition to the low frequency noise. The noise may be removed and the gain adjusted to a voltage. In addition, the second cumulative voltage V2 is accumulated by sampling the second electric charge amount (-S + N) n times and adjusting the gain, so that the second electric charge amount (S) itself sensed by the capacitance sensor 120 in addition to the low frequency noise is obtained. The noise included in the signal may be removed and the gain adjusted voltage.

The signal receiver 130 may include a sampling unit 131, a first charge accumulation unit 133, a second charge accumulation unit 134, and a gain controller 135.

The sampling unit 131 outputs the first charge amount S + N and the second charge amount (-S + N) output from the capacitance sensor 120 in response to sampling control signals SCON including information on the number of sampling. Can be sampled n times. The information about the number of sampling may be determined as the number of times the logic state of the first sampling control signal or the second sampling control signal is changed among the sampling control signals SCON. For example, the information about the number of sampling is determined as the number of times that the first sampling control signal or the second sampling control signal is changed from the first logic state to the second logic state, or the first sampling control signal or the first sample. 2 may be determined by the number of times the sampling control signal is changed from the second logic state to the first logic state. An embodiment of the sampling unit 131 will be described in more detail with reference to FIG. 2.

The gain controller 135 generates a plurality of gain control signals GCON using the digital signal Vo output from the AD converter 150 to generate a first charge accumulation unit 133 and a second charge accumulation unit 134. Can be printed as That is, the gain control unit 135 may control gain control signals for controlling the amplification degree of the first charge accumulation unit 133 and the second charge accumulation unit 134 according to the digital signal Vo having a plurality of bits ( GCON) is generated and printed.

The first charge amount accumulator 133 accumulates the first charge amount S + N sampled n times by the sampling unit 131 and adjusts the gain to remove noise included in the charge amount S itself and to adjust the gain. The first cumulative voltage V1 corresponding to the accumulated charge amount may be output. That is, by accumulating the charge amount sampled n times by the first charge amount accumulator 133, the noise is averaged and included in the charge amount S itself as the noise having a positive value and the noise having a negative value are canceled. The noise can be minimized and can have the effect of amplification by accumulation. In addition, the first charge accumulation unit 133 may adjust the gain of the first cumulative voltage V1 in response to the gain control signals GCON. That is, the first charge accumulation unit 133 reduces the first voltage V1 when the input voltage of the AD converter 150 exceeds the input voltage range of the AD converter 150, and inputs the AD converter 150. If the voltage is too small to obtain a desired value, the gain of the first voltage V1 may be adjusted to increase the first voltage V1. Referring to FIG. This will be described in more detail with reference to FIG. 2.

The second charge accumulation unit 134 accumulates the second charge amount (-S + N) sampled n times by the sampling unit 131 and adjusts the gain to remove the noise included in the charge amount (-S) itself and the gain is increased. The second cumulative voltage V2 corresponding to the adjusted cumulative charge amount may be output. That is, the noise is averaged as the noise having a positive value and the noise having a negative value are canceled by accumulating the charge amount sampled n times by the second charge accumulation accumulator 134 and thus the charge amount (-S) itself. The included noise may be minimized and may have an effect of amplification by accumulation. In addition, the second charge accumulation unit 134 may adjust the gain of the second cumulative voltage V2 in response to the gain control signals GCON. That is, the second charge accumulation unit 134 reduces the second voltage V2 when the input voltage of the AD converter 150 exceeds the input voltage range of the AD converter 150, and inputs the AD converter 150. If the voltage is too small to obtain a desired value, the gain of the second voltage V2 may be adjusted to increase the second voltage V2. Referring to FIG. This will be described in more detail with reference to FIG. 2.

The noise removing unit 145 sequentially receives the first cumulative voltage V1 and the second cumulative voltage V2 and calculates a voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2. The voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 may be output. The first voltage V1 output from the first charge accumulation unit 133 includes power supply noise generated by power applied to the system including the touch panel, and is output from the second charge accumulation unit 134. The second voltage V2 may also include power noise generated by power applied to the system including the touch panel. That is, when the conductor touches the touch panel, the power noise is generated. For example, when the smartphone is used, the power noise is generated when power is supplied from an external power source. The power supply noise may also be included in the low frequency noise N described above, and the low frequency noise N may refer to noise including the conductor noise and the power supply noise.

That is, the first cumulative voltage V1 and the second cumulative voltage V2 include noise voltages corresponding to the power supply noise and the conductor noise, and the noise voltage and the noise included in the first cumulative voltage V1. The noise voltage included in the second cumulative voltage V2 is a voltage having the same sign and the same magnitude. Accordingly, the noise removing unit 145 calculates and outputs a voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2, thereby outputting the noise voltage included in the first cumulative voltage V1. The noise voltages included in the second cumulative voltage V2 may be canceled by canceling each other. Therefore, the voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 output from the noise removing unit 140 is a voltage from which low frequency noise generated when the conductor touches the panel is removed. Can be.

The noise removing unit 140 may include a CDS control unit 143 and a CDS unit 145.

The CDS controller 143 may generate a plurality of CDS control signals CCON using the digital signal Vo output from the AD converter 150 and output the generated CDS control signals CCON to the CDS unit 145. That is, the CDS control unit 143 generates and outputs CDS gain control signals CCON that can adjust the degree of amplification of the CDS unit 145 according to the digital signal Vo having a plurality of bits.

The CDS unit 145 performs correlated double sampling of the first cumulative voltage V1 and the second cumulative voltage V2 in response to the CDS control signals CCON to remove low frequency noise and to adjust gain. The voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 may be output. That is, the CDS unit 145 subtracts the first cumulative voltage V1 and the second cumulative voltage V2 in response to the CDS control signals CCON to remove the noise voltage corresponding to the low frequency noise, and to increase the gain. The adjusted voltage difference V3 between the first accumulated voltage V1 and the second accumulated voltage V2 may be output. An embodiment and a specific operation of the noise removing unit 140 will be described in more detail with reference to FIGS. 2 to 4.

The AD converter 150 may convert the voltage difference V3 output from the noise remover 140 into a digital signal Vo and output the digital signal Vo. The digital signal Vo converted by the AD converter 150 may be used for an application.

2 is a circuit diagram illustrating an embodiment of the charge amount sensing device 100 of the touch panel of FIG. 1, and FIG. 3 is a waveform diagram of signals used in the charge amount sensing device 100 of the touch panel of FIG. 2. Hereinafter, an embodiment of each component and an operation of each component of the charge amount sensing device 100 of the touch panel will be described with reference to FIGS. 1 to 3.

The signal transmitter 110 may include a sensing controller 270, a sensing driver 273, and a sensing signal output unit 275. The sensing controller 270 may generate and output a sensing control signal SECON in response to the digital signal Vo output from the AD converter 150. The sensing driver 273 may generate and output at least one driving signal for controlling the sensing signal output unit 275 in response to the sensing control signal SECON.

The sensing driver 273 may include at least one driver for generating at least one driving signal. For example, as illustrated in FIG. 2, the sensing driver 273 turns on or turns on the first driver DR1 and the NMOS transistor N1 that generate a driving signal for turning on or off the PMOS transistor P1. The second driver DR2 may generate a driving signal that can be turned off. The first driver DR1 and the second driver DR2 may output signals having opposite logic states. Alternatively, the sensing driver 273 outputs one driving signal and is applied to the gates of the PMOS transistor P1 and the NMOS transistor N1 so that only one of the PMOS transistor P1 and the NMOS transistor N1 is turned on. You can also control it.

The sensing signal output unit 275 may output a sensing signal SEN having a first voltage VL in a first logic state or a second voltage VH in a second logic state in response to the at least one driving signal. Can be. As illustrated in FIG. 3, the sensing signal SEN may be a sinusoidal signal in which a first logic state of the first voltage VL and a second logic state of the second voltage VH are repeated. For example, the sensing signal output unit 275 may include the PMOS transistor P1 and the NMOS transistor N1 connected in series between the first voltage VL and the second voltage VH, as shown in FIG. 2. It may be an inverter including.

In the above, an embodiment of the signal transmission unit 110 has been described with reference to FIG. 2, but the signal transmission unit 110 of the present invention is not limited thereto, and the signal reception unit 130 samples the charges. If a sensing signal SEN is generated in which the first logic state and the second logic state are repeated in the accumulating period, the configuration may be different.

The capacitance sensor 120 may be modeled as a capacitor C _MUT connected between the input terminal IN and the output terminal OUT, and the first charge amount S + N and the second charge amount in response to the sensing signal SEN. (-S + N) can be output sequentially and repeatedly.

The sampling unit 131 may include a first sampling switching unit 211, a second sampling switching unit 212, and a third sampling switching unit 213 in order to sample the amount of charge output from the capacitance sensor 120. .

The first sampling switching unit 211 outputs the first charge amount S + output from the capacitance sensor 120 to the output of the sampling unit 131 in response to the first sampling control signal SCON1 among the sampling control signals SCON. N) can be sampled and output. That is, the first sampling switching unit 211 may connect or disconnect the output terminal of the capacitance sensor 120 and the input terminal of the first charge accumulation unit 133 in response to the first sampling control signal SCON1. The second sampling switching unit 212 outputs the second charge amount (-S) output from the capacitance sensor 120 to the output of the sampling unit 131 in response to the second sampling control signal SCON2 among the sampling control signals SCON. + N) can be sampled and output. That is, the second sampling switching unit 212 may connect or disconnect the output terminal of the capacitance sensor 120 and the input terminal of the second charge accumulation unit 134 in response to the second sampling control signal SCON2. The third sampling switching unit 213 may connect or disconnect the output terminal OUT of the capacitance sensor 120 and the ground voltage source VSS in response to the third sampling control signal SCON3 among the sampling control signals SCON. .

The first sampling switching unit 211 and the second sampling switching unit 212 are selectively operated, and the third sampling switching unit 213 operates an operation section of the first sampling switching unit 211 and the second sampling switching unit ( It operates between the operation sections of 212). The operation of the first to third sampling switching units 211, 212, and 213 will be described in more detail with reference to the overall operation of the signal receiving unit 130.

The first charge accumulation unit 133 may include a first operational amplifier 225, a first initialization switching unit 220, a plurality of first capacitors C1,..., Cn, and a plurality of first gain control switching units. 233_1,..., 233_n may be provided. The first operational amplifier 225 converts the input terminal (-) connected to the output terminal of the sampling unit 131, the ground voltage input terminal (+) connected to the ground voltage source VSS, and the first accumulated voltage V1 to the AD converter 150. It may include an output terminal for outputting). The first initialization switching unit 220 may connect or disconnect the input terminal (−) and the output terminal of the first operational amplifier 225 in response to the first initialization signal RST1. That is, when the touch state of the touch panel is changed or when the first charge amount S + N is sampled and accumulated n times, the first initialization switching unit 220 inputs the input terminal of the first operational amplifier 225 ( -) And the output terminal may be connected to initialize the first cumulative voltage V1.

The first capacitors C1, ..., Cn are connected in parallel between the input terminal (-) and the output terminal of the first operational amplifier 225, and the first gain control switching units 233_1, ..., 233_n The corresponding first gain control switching unit may be connected between the input terminal (−) of the first operational amplifier 225 and the corresponding first capacitor or between the output terminal of the first operational amplifier 225 and the corresponding first capacitor. That is, each of the first gain control switching units 233_1,..., 233_n corresponds to an input terminal of the first operational amplifier 225 in response to a corresponding gain control signal among the gain control signals GCON_1,..., GCON_n. A corresponding first capacitor may be connected or disconnected between the negative terminal and the output terminal. Therefore, the gain control signals GCON_1, ..., GCON_n and the first gain control switching units 233_1, ..., 233_n are used between the input terminal (-) and the output terminal of the first operational amplifier 225. By adjusting the number of connected first capacitors, the first charge amounts S + N sampled by the sampling unit 131 may be accumulated and gain may be adjusted.

As the sum of capacitances of the first capacitors connected between the input terminal (−) and the output terminal of the first operational amplifier 225 decreases, the first accumulated voltage V1 output from the first charge accumulation unit 133 increases, and As the sum of capacitances of the first capacitors connected between the input terminal (−) and the output terminal of the first operational amplifier 225 increases, the first accumulated voltage V1 output from the first charge accumulation unit 133 decreases. Therefore, as the number of gain control switching units turned on among the first gain control switching units 233_1, ..., 233_n is adjusted using the gain control signals GCON_1,. The first accumulation voltage V1 output from the charge accumulation unit 133 may be amplified or attenuated.

That is, the gain control unit 135 calculates the first cumulative voltage V1 output from the first charge accumulation unit 133 by using the digital signal Vo output from the AD converter 150. Gain control signals GCON_1,..., GCON_n are generated to reduce the number of the first capacitors connected between the input terminal (−) and the output terminal of the amplifier 225, and are output from the AD converter 150. When the first cumulative voltage V1 output from the first charge accumulation unit 133 is reduced by using the digital signal Vo, the input terminal connected between the input terminal (−) and the output terminal of the first operational amplifier 225 is used. The gain control signals GCON_1,..., GCON_n may be generated and output to increase the number of first capacitors.

The second charge amount accumulator 134 has a similar configuration to the first charge amount accumulator 133 except that a second charge amount (-S + N) is input instead of the first charge amount S + N. It can work.

Similar to the first charge accumulation unit 134, the second charge accumulation unit 134 may include a second operational amplifier 235, a second initialization switching unit 230, and a plurality of second capacitors C1,. Cn) and a plurality of second gain control switching units 234_1,..., 234_n. The second operational amplifier 235 converts the input terminal (-) connected to the output terminal of the sampling unit 131, the ground voltage input terminal (+) and the second accumulated voltage V2 connected to the ground voltage source VSS to the AD converter 150. It may include an output terminal for outputting). The second initialization switching unit 230 may connect or disconnect the input terminal (−) and the output terminal of the second operational amplifier 235 in response to the second initialization signal RST2. That is, when the touch state of the touch panel changes or when the second charge amount (-S + N) is sampled and accumulated n times, the second initialization switching unit 230 receives an input terminal of the second operational amplifier 235. The second cumulative voltage V2 may be initialized by connecting the negative terminal and the output terminal.

The second capacitors C1, ..., Cn are connected in parallel between the input terminal (-) and the output terminal of the second operational amplifier 235, and the second gain control switching units 234_1, ..., 234_n The corresponding second gain control switching unit may be connected between the input terminal (−) of the second operational amplifier 235 and the corresponding second capacitor or between the output terminal of the second operational amplifier 235 and the corresponding second capacitor. That is, each of the second gain control switching units 234_1,..., 234_n is an input terminal of the second operational amplifier 235 in response to a corresponding gain control signal among the gain control signals GCON_1,..., GCON_n. A corresponding second capacitor may be connected or disconnected between the negative terminal and the output terminal. Therefore, between the input terminal (-) and the output terminal of the second operational amplifier 235 by using the gain control signals GCON_1, ..., GCON_n and the second gain control switching units 233_1, ..., 233_n. By adjusting the number of connected second capacitors, the second charge amounts (-S + N) sampled by the sampling unit 131 may be accumulated and gain may be adjusted. The same reference numeral among the first capacitors and the second capacitors may have the same capacitance value.

As the capacitance sum of the second capacitors connected between the input terminal (−) and the output terminal of the second operational amplifier 235 decreases, the second cumulative voltage V2 output from the second charge accumulation unit 134 increases, and As the capacitance sum of the second capacitors connected between the input terminal (−) and the output terminal of the second operational amplifier 235 increases, the second cumulative voltage V2 output from the second charge accumulation unit 134 decreases. Accordingly, the second gain control switching units 234_1, ..., 234_n are adjusted using the gain control signals GCON_1,..., GCON_n to adjust the number of gain control switching units turned on. The second accumulation voltage V2 output from the charge accumulation unit 134 may be amplified or attenuated.

That is, the gain control unit 135 calculates the second cumulative voltage V2 output from the second charge accumulation unit 134 by using the digital signal Vo output from the AD converter 150. Gain control signals GCON_1,..., GCON_n are generated to reduce the number of the second capacitors connected between the input terminal (−) and the output terminal of the amplifier 235, and are output from the AD converter 150. When the second cumulative voltage V2 output from the second charge accumulation unit 134 is reduced by using the digital signal Vo, the input terminal is connected between the input terminal (-) and the output terminal of the second operational amplifier 235. Gain control signals GCON_1,..., And GCON_n may be generated and output to increase the number of second capacitors.

The first to third sampling control signals SCON_1, SCON_2, and SCON_3, the first and second initialization signals RST_1 and RST_2, and the gain control signals GCON_1,..., GCON_n described above are gains. The control unit 135 may generate and output the output signal, or the gain control unit 135 and other components may generate and output the divided signals.

The CDS unit 145 performs correlated double sampling of the first cumulative voltage V1 and the second cumulative voltage V2 in response to the CDS control signals CCON to remove low frequency noise and to adjust gain. The voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 may be output. That is, the CDS unit 145 subtracts the first cumulative voltage V1 and the second cumulative voltage V2 in response to the CDS control signals CCON to remove the noise voltage corresponding to the low frequency noise, and to increase the gain. The adjusted voltage difference V3 between the first accumulated voltage V1 and the second accumulated voltage V2 may be output.

The CDS unit 145 may include a selector 243, a first CDS capacitor Cs, a CDS operational amplifier 265, a CDS initialization switch 260, second CDS capacitors CC1,. A plurality of CDS gain control switching units 267_1,..., 267_n may be provided.

The selector 243 is configured to output the first cumulative voltage V1 and the second cumulative voltage output from the signal receiver 130 in response to the first and second selection signals SEL1 and .SEL2 among the CDS control signals CCON. (V2) can be output sequentially. The selector 243 may include a first select switch 243 and a second select switch 245. The first selection switching unit 243 connects or cuts off an output terminal of the first charge accumulation unit 133 and one end of the first CDS capacitor Cs in response to the first selection signal SEL1. V1) may be delivered to or disconnected from the first CDS capacitor Cs. The second selection switching unit 245 connects or disconnects the output terminal of the second charge accumulation unit 134 and one end of the first CDS capacitor Cs in response to the second selection signal SEL2 to prevent the second leakage voltage ( V2) may be delivered to or disconnected from the first CDS capacitor Cs. The first selective switching unit 243 and the second selective switching unit 243 may be selectively turned on without being turned on at the same time.

The first CDS capacitor Cs may be connected between an output terminal of the selector 240 and an input terminal (−) of the CDS operational amplifier 265. The CDS operational amplifier 265 includes an input terminal (-) connected to the other end of the first CDS capacitor Cs, a ground voltage input terminal (+) connected to the ground voltage source VSS, and a first cumulative voltage V1 and a second accumulation. An output terminal for outputting a voltage difference V3 of the voltage V2 may be provided. The CDS initialization switching unit 260 outputs the CDS control signals in a section other than a section in which the CDS operational amplifier 265 outputs the voltage difference V3 and a section in which the AD converter 150 outputs the digital signal Vo. The voltage difference Vo may be initialized by connecting an input terminal (−) and an output terminal of the CDS operational amplifier 265 in response to the CDS initialization signal CRST. The second CDS capacitors CC1,..., CCn may be connected in parallel between the input terminal (−) and the output terminal of the CDS operational amplifier 265, and the CDS gain control switching units 267_1,..., 267_n. The CDS operational amplifier 265 selects each of the second CDS capacitors CC1,..., CCn in response to the corresponding CDS gain control signals CCON_1,..., Or CCON_n among the CDS control signals CCON. It can be connected or disconnected between the input terminal (-) and the output terminal of.

By the operation of the first CDS capacitor Cs, the CDS operational amplifier 265, the second CDS capacitors CC1, ..., CCn and the CDS gain control switching units 267_1, ..., 267_n, The voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 may be generated and the gain of the voltage difference V3 may be adjusted. That is, each of the CDS gain control switching units 267_1,..., 267_n is an input terminal of the CDS operational amplifier 265 in response to the corresponding CDS gain control signal among the CDS gain control signals CCON1,..., CCONn. Since the corresponding second CDS capacitor can be connected or disconnected between the negative terminal and the output terminal, the voltage difference V3 is adjusted by adjusting the number of second CDS capacitors connected between the input terminal (-) and the output terminal of the CDS operational amplifier 265. You can adjust the gain. As the capacitance sum of the second CDS capacitors connected between the input terminal (-) and the output terminal of the CDS operational amplifier 265 decreases, the voltage difference V3 increases, and between the input terminal (-) and the output terminal of the CDS operational amplifier 265. As the capacitance sum of the second CDS capacitors connected to the voltage increases, the voltage difference V3 decreases. Accordingly, as the number of CDS gain control switching units turned on among the CDS gain control switching units 267_1, ..., 267_n is adjusted using the CDS gain control signals CCON_1,. The difference V3 can be amplified or attenuated.

Therefore, the CDS controller 143 is connected between the input terminal (-) and the output terminal of the CDS operational amplifier 265 when amplifying the voltage difference V3 using the digital signal Vo output from the AD converter 150. The CDS gain control signals CCON_1,..., CCON_n are generated to reduce the number of the second CDS capacitors, and the voltage difference V3 is generated using the digital signal Vo output from the AD converter 150. ), CDS gain control signals CCON_1, ..., CCON_n are generated to increase the number of the second CDS capacitors connected between the input terminal (-) and the output terminal of the CDS operational amplifier 265. Can be output.

The CDS unit 145 is configured to connect or block the other end of the first CDS capacitor Cs and the input terminal (-) of the CDS operational amplifier 265 in response to the holding signal HOL among the CDS control signals CCON. 255 may be further provided. For example, the holding unit 255 may have a first cumulative voltage V1 or a second cumulative voltage V2 in a period in which the AD converter 150 converts the voltage difference V3 into a digital signal Vo. Application to the input terminal of the CDS operational amplifier 265 can be prevented. That is, when the operation is performed at the stage after the holding unit 255 and the first accumulation voltage V1 or the second accumulation voltage V2 is not applied to the input terminal of the CDS operational amplifier 265, the holding unit 255 may block the input terminals of the first CDS capacitor Cs and the CDS operational amplifier 265. The operation of the holding unit 255 will be described in more detail with reference to FIG. 3 with reference to the charge amount sensing device 100 of the touch panel.

The first and second selection signals SEL1 and SEL2, the CDS initialization signal CRST, the holding signal HOL, and the CDS gain control signals CCON1,..., CCONn described above are stored in the CDS controller 143. May be generated and output, or may be generated and output by dividing the signals by the CDS control unit 143 and other components.

Hereinafter, an operation of the charge amount sensing device 100 of the touch panel will be described with reference to FIGS. 1 to 3.

When the touch panel is initialized to recognize a touch state (for example, when power is applied to the touch panel), when the touch state of the touch panel is changed, or the first charge amount is sampled n times and accumulated In one case, the first initialization signal RST1 is changed from the first logic state to the second logic state so that the first initialization switch 220 is turned on. In this case, since the input terminal (−) and the output terminal of the first operational amplifier 225 are directly connected, the output of the first charge accumulation unit 133 is initialized to the ground voltage. When the touch panel is initialized to recognize a touch state, when the touch state of the touch panel is changed, or when the second amount of charge is sampled and accumulated n times, the second initialization signal RST2 is first. The second initialization switching unit 230 is turned on by changing from the logic state to the second logic state. In this case, since the input terminal (−) and the output terminal of the second operational amplifier 235 are directly connected, the output of the second charge accumulation unit 134 is initialized to the ground voltage.

Thereafter, at the time t1, the capacitance sensor 120 starts to output the first charge amount S + N according to the touch state of the touch panel in response to the applied sensing signal SEN, and at the time t2, the capacitance sensor 120. ) Starts to output the second charge amount (-S + N) according to the touch state of the touch panel in response to the sensing signal SEN applied.

The sampling unit 131 may output the first charge amount S output from the capacitance sensor 120 in response to the first sampling control signal SCON1 at the time when the sensing signal SEN is changed from the second logic state to the first logic state. The second charge amount output from the capacitance sensor 120 in response to the second sampling control signal SCON2 at the time when the sensing signal SEN is changed from the first logic state to the second logic state is sampled. -S + N) can be sampled. In addition, the sampling unit 131 may include a first sampling control signal SCON1 and a second sampling control signal, which is an interval between an operation period of the first sampling switching unit 211 and an operation period of the second sampling switching unit 212. The output terminal of the capacitance sensor 120 may be connected to the ground voltage source VSS in a section in which SCON2 is simultaneously in the first logic state.

That is, when the third sampling control signal SCON_3 is in the second logic state and the second and third sampling control signals SCON_2 and SCON_3 are in the first logic state, the third sampling switching unit 213 is turned on and the first sampling state is turned on. The first and second sampling switching units 211 and 212 are turned off so that the output of the capacitance sensor 120 is connected to the ground voltage source VSS and does not sample the first charge amount or the second charge amount. When the first sampling control signal SCON_1 is in the first logic state and the second and third sampling control signals SCON_2 and SCON_3 are in the second logic state, the first sampling switching unit 211 is turned on and the second and Since the third sampling switching units 212 and 213 are turned off, the output of the capacitance sensor 120 may be input to the first charge accumulation unit 133 to sample the first charge amount. When the second sampling control signal SCON_2 is in the first logic state and the first and third sampling control signals SCON_1 and SCON_3 are in the second logic state, the second sampling switching unit 212 is turned on and the first and second sampling control signals SCON_1 and SCON_2 are turned on. Since the third sampling switching units 211 and 213 are turned off, the output of the capacitance sensor 120 may be input to the second charge accumulation unit 134 to sample the second charge amount.

In FIG. 3, the sampling count and the cumulative number n are 4, but the present invention is not limited thereto, and the sampling count and the cumulative number n may be other various times. In the case of FIG. 3, the sampling unit 131 has four times when the first sampling control signal SCON_1 is changed from the first logic state to the second logic state (the sensing signal SEN is changed from the second logic state to the first logic state). The first charge amount is sampled at the fourth time point, and the first charge amount accumulator 133 accumulates the first charge amounts sampled four times and adjusts a gain to adjust the first accumulated voltage V1 corresponding to the accumulated charge amount. ) Can be printed. In addition, the sampling unit 131 changes four times when the second sampling control signal SCON_2 is changed from the first logic state to the second logic state (the sensing signal SEN is changed from the first logic state to the second logic state). The second charge amount is sampled, and the second charge amount accumulator 134 accumulates the second charge amounts sampled four times and adjusts a gain to obtain a second accumulated voltage V2 corresponding to the accumulated charge amount. You can print Since the method of accumulating the sampled first charge amounts or the second charge amounts and adjusting the gain has been described in detail above, a detailed description thereof will be omitted.

The first selection switching unit 243 outputs the first accumulated voltage V1 output by the first charge accumulation unit 133 to the first CDS capacitor Cs in response to the first selection signal SEL1 until time t3. can do. In addition, the second selection switching unit 245 outputs the second accumulated voltage V2 output from the second charge accumulation unit 134 in response to the second selection signal SEL2 in the interval between the time points t3 and t4. Can output to 1 CDS capacitor (Cs).

The output voltage V3 of the CDS unit 145 is a time t2 in response to the CDS initialization signal CRST (a time point at which the AD converter 150 changes the voltage difference V3 previously input to the digital signal Vo). ) Is initialized to the ground voltage VSS in the period between the time point t3 and the time period between the time point t3 and the time point t4. The CDS unit 145 adjusts the inputted first and second accumulated voltages V1 and V2. The subtraction operation and the gain may be adjusted to output a voltage difference V3 between the first accumulated voltage V1 and the second accumulated voltage V2 from which the low frequency noise N has been removed. In addition, the AD converter 150 is enabled in response to the AD converter enable signal ADC_EN during the time t4 to the time t6, so that the voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2. May be converted into a digital signal Vo and output. In this case, the holding unit 255 cuts off the connection between the first CDS capacitor Cs and the input terminal (-) of the CDS operational amplifier 265 in response to the holding signal HOL in the period between the time points t4 and t6. Thus, before the operation of the AD converter 150 is completed, the voltage difference V3 between the new first accumulated voltage V1 and the second accumulated voltage V2 may be prevented from being input to the AD converter 150. In addition, while the AD converter 150 is operating, the sampling unit 131 may start sampling the new first electric charge from the time t5.

In FIG. 3, a method of operating the charge amount sensing device 100 of the touch panel is described according to an embodiment of the present invention, but for operating the charge amount sensing device 100 of the touch panel according to an embodiment of the present invention. The signals do not necessarily have a waveform as shown in FIG. 3, and the signals shown in FIG. 3 may have other waveforms as long as they can operate as described above.

FIG. 4 is a circuit diagram schematically illustrating the first charge amount accumulator 133, the second charge amount accumulator 134, and the CDS unit 145 of FIG. 2.

1 to 4, a parallel connection is made between an input terminal (−) and an output terminal of the first operational amplifier 225 among the first capacitors C1,..., Cn of the first charge accumulation unit 133. The first capacitors may be modeled as one capacitor C _F as shown in FIG. 4. In addition, among the second capacitors C1,..., Cn of the second charge accumulation unit 134, second capacitors connected in parallel between the input terminal (−) and the output terminal of the second operational amplifier 235 are also illustrated in FIG. 4. As shown in FIG. 1, one capacitor C _F may be modeled. The capacitance of the first capacitors connected between the input terminal (-) and the output terminal of the first operational amplifier 225 and the capacitance of the second capacitors connected between the input terminal (-) and the output terminal of the second operational amplifier 235 have the same capacitance. Therefore, in FIG. 4, the same capacitor C _F was modeled. In addition, the second CDS capacitors connected between the input terminal (−) and the output terminal of the CDS operational amplifier 265 among the second CDS capacitors CC1,..., CCn also have one capacitor ( C _H ).

As described above, the first charge amount accumulator 133 outputs the first voltage V1 in which the sampled first charge amount S + N is accumulated n times and whose gain is adjusted, and the second charge amount accumulator 134. ) May output the second voltage V2 in which the sampled second charge amount (-S + N) is accumulated n times and the gain is adjusted. In addition, since the first selective switching unit 243 and the second selective switching unit 245 are selectively operated, the first selective switching unit 243 performs the first selection signal in the interval between the time t1 and the time t3 in FIG. 3. In response to SEL1, the first cumulative voltage V1 is output, and in a period between a time point t3 and a time point t5 in FIG. 3, the second selection switching unit 245 responds to the second selection signal SEL2 in response to the second selection signal SEL2. The accumulated voltage V2 may be output. In this case, the CDS unit 145 may subtract the first cumulative voltage V1 and the second cumulative voltage V2 and adjust the gain to output the third voltage V3. That is, since the CDS unit 145 subtracts the second cumulative voltage V2 from the first cumulative voltage V1, the noise included in the first cumulative voltage V1 and the second cumulative voltage V2 is common. The voltage (low frequency noise component (N)) is canceled out of each other, and the sampled charge amounts (S and -S) excluding the noise component are subtracted to generate a voltage corresponding to the charge amount of 2S, by C _S / C _H. The voltage difference V3 in a state where the gain is adjusted may be output.

By the above operation, the voltage difference V3 between the first cumulative voltage V1 and the second cumulative voltage V2 output from the charge accumulation unit 133 may be expressed by Equation 1 below.

In Equation 1, C _F denotes a sum of capacitances of first capacitors connected between an input terminal (−) and an output terminal of the first operational amplifier 225 among the first capacitors C1,..., Cn. Among the first capacitors C1, ..., Cn, the capacitance sum of the first capacitors connected between the input terminal (-) and the output terminal of the first associative amplifier 225 and the second capacitors C1, ..., Cn. , Cn is equal to the sum of capacitances of the second capacitors connected between the input terminal (-) and the output terminal of the second operational amplifier 235, so that C _F is the second of the capacitors (C1, ..., Cn). It may mean the sum of capacitances of the second capacitors connected between the input terminal (−) and the output terminal of the second operational amplifier 235. In Equation 1, C _H is a sum of capacitances of second CDS capacitors connected between an input terminal (−) and an output terminal of the CDS operational amplifier 265 among the second CDS capacitors CC1,..., CCn. it means. V _N refers to a noise voltage included in the first cumulative voltage V1 and the second cumulative voltage V2 due to the low frequency noise.

FIG. 5 is a diagram for describing a change in charge amount according to a touch state of a conductor in the case of the capacitance sensor 120 of FIG. 1.

1 to 5, the capacitance sensor 120 of FIG. 5 has an input terminal and an output terminal formed on the same plane, and the input terminal IN and the output terminal OUT without the conductor being touched by the touch panel. The charge amount of Q is generated in between, and the charge amount of Q is output to the output terminal OUT. However, when the conductor is touched by the touch panel, a charge amount of Q + ΔQ occurs between the input terminal IN and the output terminal OUT, and outputs the charge amount of Q + ΔQ to the output terminal OUT.

FIG. 6 is a diagram for describing a change in charge amount according to a touch state of a conductor in accordance with another embodiment of the capacitance sensor 120 of FIG. 1.

1 to 6, unlike the capacitance sensor of FIG. 6, the capacitance sensor 120 of FIG. 6 has an input terminal and an output terminal formed on different planes, and the input terminal (not being touched by the conductor). The charge amount of Q is generated between IN) and the output terminal OUT, and the charge amount of Q is output to the output terminal OUT. However, when the conductor is touched by the touch panel, a charge amount of Q + ΔQ occurs between the input terminal IN and the output terminal OUT, and outputs the charge amount of Q + ΔQ to the output terminal OUT.

The charge amount of Q + ΔQ shown in FIGS. 5 and 6 corresponds to the charge amount S of FIG. 1 and is omitted in FIGS. 5 and 6, but the conductor and the touch panel when the conductor touches the touch panel. Between the above-described conductor noise may occur.

The structure of the capacitance sensor 120 of FIGS. 5 and 6 is only an embodiment of the present invention, and the capacitance sensor 120 of the present invention is not limited to the structure of FIGS. 5 and 6. That is, the capacitive sensor 120 may have various structures if the amount of charge corresponding to the touch state of the touch panel is output in response to the sensing signal applied to the input terminal with the input terminal and the output terminal.

As described above, optimal embodiments have been disclosed in the drawings and the specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (14)

A signal transmission unit generating and outputting a sensing signal including information on a sampling time point;
An input terminal for receiving the sensing signal and a first charge amount having a sensed positive value and a second charge amount having a negative value are sequentially and repeatedly outputted when the conductor touches the touch panel in response to the received sensing signal A capacitance sensor comprising an output stage;
A signal receiver configured to sample and accumulate the first charge amount and the second charge amount output from the capacitance sensor n times (n is a natural number), respectively, and adjust a gain to output a first accumulated voltage and a second accumulated voltage;
By receiving the first cumulative voltage and the second cumulative voltage sequentially and calculating the voltage difference between the first cumulative voltage and the second cumulative voltage, low-frequency noise generated when the conductor touches the touch panel is removed. A noise removing unit for outputting the voltage difference; And
And an analog to digital (AD) converter configured to convert the voltage difference into a digital signal and output the digital signal. The method of claim 1, wherein the low frequency noise,
When the conductor touches the touch panel, the touch panel includes power noise generated by power applied to a system including the touch panel, and conductor noise generated between the touch panel and the conductor. Charge detection device. The method of claim 2, wherein the first cumulative voltage and the second cumulative voltage, respectively,
A noise voltage corresponding to the power supply noise and the conductor noise,
The voltage difference between the first cumulative voltage and the second cumulative voltage is
And a voltage difference between a voltage corresponding to the first charge amount and a voltage corresponding to the second charge amount, in which the noise voltage is canceled by the subtraction operation of the first accumulated voltage and the second accumulated voltage. Sensing device. The method of claim 1, wherein the sensing signal,
A first logic state and a second logic state are repeated in a section in which the signal receiver samples and accumulates the first and second charges,
The capacitance sensor,
Outputting the first charge amount at a time point when the sensing signal is changed from the first logic state to the second logic state, and at the time point when the sensing signal is changed from the second logic state to the first logic state; A charge amount sensing device of a touch panel, characterized in that for outputting two charge amounts. The method of claim 1, wherein the noise removing unit,
A CDS controller generating a plurality of CDS control signals in response to the digital signal; And
In response to the CDS control signals, the first cumulative voltage and the second cumulative voltage are correlated double sampling to remove the low frequency noise, and the gain is adjusted to the first cumulative voltage and the second cumulative voltage. And a CDS unit for outputting a voltage difference between voltages. The method of claim 5, wherein the CDS unit,
A selector configured to sequentially output a first cumulative voltage and a second cumulative voltage output from the signal receiver in response to first and second selection signals among the CDS control signals;
A first CDS capacitor having one end connected to an output end of the selection unit;
A CDS operational amplifier including an input terminal connected to the other end of the first CDS capacitor, a ground voltage input terminal connected to a ground voltage source, and an output terminal outputting a voltage difference between the first accumulated voltage and the second accumulated voltage;
In a section other than a section for outputting the voltage difference in the CDS operational amplifier and a section for outputting the digital signal in the AD converter, an input terminal and an output terminal of the CDS operational amplifier are connected in response to a CDS initialization signal among the CDS control signals. A CDS initialization switching unit configured to initialize the voltage difference by connecting;
A plurality of second CDS capacitors connected in parallel between an input terminal and an output terminal of the CDS operational amplifier; And
And a plurality of CDS gain control switching units for connecting or disconnecting each of the second CDS capacitors between an input terminal and an output terminal of the CDS operational amplifier in response to a corresponding CDS gain control signal among the CDS control signals. Charge amount sensing device of the touch panel. The method of claim 6, wherein the CDS control unit,
In order to amplify the voltage difference between the first cumulative voltage and the second cumulative voltage, the number of the second CDS capacitors connected between an input terminal and an output terminal of the CDS operational amplifier is decreased, and the first cumulative voltage and the second cumulative voltage are reduced. When the voltage difference of the cumulative voltage is to be attenuated, the amount of charge control of the touch panel is generated such that the gain control signals are generated to increase the number of the second CDS capacitors connected between the input terminal and the output terminal of the CDS operational amplifier. Device. The method of claim 6, wherein the selection unit,
A first selective switching unit configured to transfer or block the first accumulated voltage to the first CDS capacitor in response to the first selection signal; And
And a second selection switching unit configured to transfer or block the second accumulated voltage to the first CDS capacitor in response to the second selection signal. The method of claim 6, wherein the CDS unit,
And a holding unit for connecting or disconnecting the other end of the first CDS capacitor and the input end of the CDS operational amplifier in response to a holding signal among the CDS control signals. The method of claim 1, wherein the signal receiving unit,
A sampling unit configured to sample the first charge amount and the second charge amount output from the capacitance sensor n times in response to sampling control signals including information about a sampling number;
A gain controller configured to generate and output a plurality of gain control signals using the digital signal output from the AD converter;
A first charge accumulation unit configured to accumulate the first charges sampled n times in response to the gain control signals, and adjust gain to output the first accumulated voltage; And
And a second charge amount accumulator configured to accumulate the second charge amounts sampled n times in response to the gain control signals, and adjust a gain to output the second accumulated voltage. The method of claim 10, wherein the sampling unit,
A first sampling switching unit configured to sample the first charge amount in response to a first sampling control signal among the sampling control signals and to output the first charge amount to the first charge amount accumulation unit;
A second sampling switching unit sampling the second charge amount in response to a second sampling control signal among the sampling control signals and outputting the second charge amount to the second charge amount accumulation unit; And
A third sampling switching unit configured to connect or disconnect an output terminal of the capacitance sensor and a ground voltage source in response to a third sampling control signal among the sampling control signals,
And wherein the first sampling switching unit and the second sampling switching unit are selectively operated, and wherein the third sampling switching unit is operated between an operating section of the first sampling switching unit and an operating section of the second sampling switching unit. Panel charge detector. The method of claim 10, wherein the first charge amount accumulator,
A first operational amplifier including an input terminal connected to an output terminal of the sampling unit, a ground voltage input terminal connected to a ground voltage source, and an output terminal outputting the first accumulated voltage to the noise removing unit;
When the touch state of the touch panel is changed or when the first charge amount is sampled and accumulated n times, the first accumulated voltage is initialized by connecting an input terminal and an output terminal of the first operational amplifier in response to a first initialization signal. A first initialization switching unit;
A plurality of first capacitors connected in parallel between an input terminal and an output terminal of the first operational amplifier; And
A plurality of first gain control switching units for connecting or disconnecting each of the first capacitors between an input terminal and an output terminal of the first operational amplifier in response to a corresponding gain control signal among the gain control signals,
The second charge amount accumulator,
A second operational amplifier including an input terminal connected to an output terminal of the sampling unit, a ground voltage input terminal connected to the ground voltage source, and an output terminal outputting the second accumulated voltage to the noise removing unit;
When the touch state of the touch panel is changed or when the second charge amount is sampled and accumulated n times, the second accumulated voltage is initialized by connecting an input terminal and an output terminal of the second operational amplifier in response to a second initialization signal. A second initialization switching unit;
A plurality of second capacitors connected in parallel between an input terminal and an output terminal of the second operational amplifier; And
And a plurality of second gain control switching units for connecting or disconnecting each of the second capacitors between an input terminal and an output terminal of the second operational amplifier in response to a corresponding gain control signal among the gain control signals. Charge amount sensing device of the touch panel. The method of claim 12, wherein the gain control unit,
When amplifying the first and second cumulative voltages, the number of the first capacitors connected between an input terminal and an output terminal of the first operational amplifier and the second capacitors connected between an input terminal and an output terminal of the second operational amplifier To reduce the number of capacitors and attenuate the first and second cumulative voltages, the number of the first capacitors connected between an input terminal and an output terminal of the first operational amplifier and an input terminal and an output terminal of the second operational amplifier And generating the gain control signals to increase the number of the second capacitors connected thereto. The method of claim 1, wherein the signal transmission unit,
A sensing controller configured to generate and output a sensing control signal in response to the digital signal output from the AD converter;
At least one sensing driver configured to generate and output at least one driving signal in response to the sensing control signal; And
And a sensing signal output unit configured to generate and output the sensing signal in response to the at least one driving signal.

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