KR101266812B1 - Apparatus and method for sensing charge of touch panel - Google Patents

Abstract

PURPOSE: Electric charge detection device and method of a touch panel are provided to minimize noise by attenuating noise by not amplifying electric charge but by accumulating electric charge according to a state of touch of a touch panel and to improve a signal-to-noise ratio compared to an existing technique. CONSTITUTION: An electric charge detection device(100) of a touch panel includes a signal transmission unit(110), a capacitance sensor(120), a signal reception unit(130), and an AD converter(140). The signal transmission unit generates and outputs a sensing signal(SEN) including information about a sampling time. The capacitance sensor receives the sensing signal outputted from the signal transmission unit and outputs electric charge(Q or Q + delta Q) according to a state of touch of a touch panel in response to the sensing signal received with an output end(OUT). The signal reception unit accumulates the electric charge by sampling electric charge outputted from the capacitance sensor n times and controls a gain. [Reference numerals] (110) Signal transmission unit; (131) Sampling unit; (133) Electric charge accumulating unit; (135) Gain control unit

Description

Apparatus and method for sensing charge of touch panel

The present invention relates to a device for detecting a charge amount of a touch panel and a method for detecting a charge amount of a touch panel, and more particularly, to an apparatus and method for detecting a charge amount of a touch panel which minimizes noise to minimize noise and ensures sufficient sensitivity even with small changes in charge amount. will be.

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, amplification of a simple signal also amplifies the noise at the same rate, resulting in a problem that the noise increases.

An object of the present invention is to provide a charge amount sensing device of a touch panel that attenuates noise to minimize noise and ensure sufficient sensitivity even with small charge amount changes.

Another object of the present invention is to provide a method for detecting a charge amount of a touch panel that attenuates noise to minimize noise and ensure sufficient sensitivity even with small changes in charge amount.

According to an aspect of the present invention, there is provided a device for detecting a charge amount of a touch panel, the 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 the A capacitance sensor comprising an output terminal for outputting an amount of charge according to a touch state of the touch panel in response to the received sensing signal, and accumulating and accumulating n times (n is a natural number) of the amount of charge output from the capacitance sensor and adjusting gain. And a signal receiver for outputting a voltage corresponding to the accumulated charge amount of which noise is removed and gain is adjusted, and an analog to digital (AD) converter for converting and outputting the voltage output from the signal receiver to a digital signal.

The signal receiver may include: a gain controller configured to generate and output a plurality of gain control signals by using the digital signal output from the AD converter, and a first sampling control signal and a second sampling control signal including information about a sampling frequency. A sampling unit for sampling the charge amounts output from the capacitance sensor n times in response thereto and accumulating the charge amounts sampled n times in response to the gain control signals and adjusting a gain to accumulate charge amounts for outputting a voltage corresponding to the accumulated charge amount It may be provided.

The sampling unit samples the amount of charge output from the capacitance sensor in response to the second sampling control signal and the first sampling switching unit for connecting or disconnecting the output terminal of the capacitance sensor and the ground voltage source in response to the first sampling control signal. And a second sampling switching unit for outputting, wherein the first sampling switching unit and the second sampling switching unit may be selectively operated.

The sensing signal is a signal in which a first logic state and a second logic state are repeated in a section in which the signal receiver samples and accumulates the charge amounts, and the second sampling control signal is a signal in which the signal receiver samples and accumulates the charge amounts. The signal having the same phase as the sensing signal in the interval, and the first sampling control signal may be a signal having a phase opposite to the second sampling control signal.

The charge accumulation unit includes 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 a voltage corresponding to the accumulated charge amount to the AD converter, and a touch state of the touch panel In case of change or when the charge amount is sampled and accumulated n times, an initialization switching unit for connecting the input terminal and the output terminal of the operational amplifier to initialize the voltage corresponding to the accumulated charge in response to an initialization signal, and the input terminal of the operational amplifier; A plurality of gain control switching units which connect or disconnect each of the capacitors between an input terminal and an output terminal of the operational amplifier in response to a plurality of capacitors connected in parallel between an output terminal and a corresponding gain control signal among the gain control signals; It may be provided.

The gain controller decreases the number of capacitors connected between an input terminal and an output terminal of the operational amplifier when the voltage corresponding to the cumulative charge amount is increased, and decreases the voltage corresponding to the accumulated electric charge amount by the operational amplifier. The gain control signals may be generated to increase the number of the capacitors connected between an input terminal and an output terminal of the capacitor.

The signal transmission unit generates and outputs the sensing 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 charges, and the signal receiver generates the sensing signal by the first logic. The amount of charges output from the capacitance sensor may be sampled at the time when the second logic state is changed in the state.

The signal transfer unit is a sensing controller for generating and outputting a sensing control signal in response to the digital signal output from the AD converter, at least one sensing driver for generating and outputting at least one driving signal in response to the sensing control signal; A sensing signal output unit may be provided to generate and output the sensing signal in response to at least one driving signal.

According to another aspect of the present invention, there is provided a method of detecting a charge amount of a touch panel, the method including: generating and outputting a sensing signal including information on a sampling time point, receiving the sensing signal, and receiving the received signal. Outputting an amount of charge according to a touch state of the touch panel in a capacitance sensor in response to a sensing signal, and an amount of charge output from the capacitance sensor in response to a first sampling control signal and a second sampling control signal including information about a sampling frequency; Sampling n times (n is a natural number) and accumulating the n-times sampled charge amounts in response to a plurality of gain control signals and adjusting a gain to output a voltage corresponding to the accumulated charge amount where noise is removed and gain is adjusted. And converting the voltage into a digital signal and outputting the converted digital signal.

According to an embodiment of the present disclosure, an apparatus for detecting a charge amount of a touch panel and a method for detecting an amount of charge of a touch panel according to an exemplary embodiment of the present invention accumulate the amount of charge according to a touch state of a touch panel without amplifying the charge amount, thereby attenuating the noise by averaging the noise. Minimize and improve the signal-to-noise ratio (SNR) compared to the prior art. In addition, the charge amount sensing device of the touch panel and the charge amount sensing method of the touch panel have an advantage of amplifying by accumulating the amount of charge according to the touch state of the touch panel, thereby ensuring sufficient sensitivity even with a small amount of charge change.

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.
FIG. 4 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. 5 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 of FIG. 1.
FIG. 6 is a diagram illustrating a difference between noise when amplifying the sensed charge amount and accumulating the sensed charge amount.
7 is a flowchart illustrating a method of detecting a charge amount of a touch panel according to an exemplary embodiment of the inventive concept.

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, the charge sensing device 100 of a touch panel may include a signal transmitter 110, a capacitance sensor 120, a signal receiver 130, and an analog to digital (AD) converter 140. .

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 a time point at which a logic state of the sensing signal SEN is changed. For example, a time point when the sensing signal SEN is changed from the first logic state to the second logic state is the sampling time point, or a time point when the sensing signal SEN is changed from the second logic state to the first logic state. It may be the sampling time point. 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 may receive an amount of charge Q or Q according to a touch state of the touch panel in response to the input terminal IN receiving the sensing signal SEN output from the signal transmission unit 110 and the received sensing signal SEN. And an output terminal OUT for outputting Q + ΔQ). That is, 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. In addition, for convenience of description below, the amount of charge output from the capacitance sensor 120 when the conductor does not touch the touch panel is defined as 'Q', and the capacitance sensor when the conductor touches the touch panel. The amount of charge output at 120 is defined as 'Q + ΔQ'. ΔQ may have a positive value or a negative value. The amount of charge sensed by the capacitance sensor 120 according to the touch state will be described in more detail with reference to FIG. 4 or 5.

The signal receiver 130 accumulates and accumulates the amount of charge (Q or Q + ΔQ) output from the capacitance sensor 120 n times (n is a natural number) and adjusts gain to remove noise and adjust gain. The voltage V1 or V2 corresponding to the accumulated charge amount may be output. The signal receiver 130 may include a sampling unit 131, a charge accumulation unit 133, and a gain controller 135.

The sampling unit 131 outputs the amount of charges Q or Q + ΔQ output from the capacitance sensor 120 in response to the first sampling control signal SCON1 and the second sampling control signal SCON2 including information on the number of sampling. ) Can be sampled n times. The first sampling control signal SCON1 and the second sampling control signal SCON2 may have opposite phases. The information about the number of sampling may be determined as the number of times the logic state of the first sampling control signal SCON1 or the second sampling control signal SCON2 is changed. For example, the information on the number of times of sampling is the number of times that the second sampling control signal SCON2 is changed from the first logic state to the second logic state or the second sampling control signal SCON2 is first in the second logic state. It can be determined by the number of times to change to a logic state. An embodiment of the sampling unit 131 will be described in more detail with reference to FIG. 2.

The gain controller 135 may generate a plurality of gain control signals GCON using the digital signal Vo output from the AD converter 140 and output the generated gain control signals GCON to the charge accumulation unit 133. That is, the gain control unit 135 generates and outputs gain control signals GCON that can adjust the degree of amplification of the charge accumulation unit 133 according to the output digital signal Vo.

The charge accumulation unit 133 may accumulate the charge amount sampled n times by the sampling unit 131 and adjust the gain to output a voltage V1 or V2 corresponding to the accumulated charge amount from which the noise is removed and the gain is adjusted. That is, by accumulating the amount of charge sampled n times in the charge accumulation unit 133, the noise having a positive value and the noise having a negative value are canceled to minimize the noise, thereby minimizing the noise, and the effect of amplification by accumulation. It can have In addition, the charge accumulation unit 133 may adjust the gain of the voltage V1 or V2 corresponding to the accumulated charge amount in response to the gain control signals GCON. That is, when the input voltage of the AD converter 140 exceeds the input voltage range of the AD converter 140, the charge accumulation unit 133 reduces the voltage V1 or V2 corresponding to the accumulated charge amount into the input voltage range. When the input voltage of the AD converter 140 is too small to obtain a desired value, the voltage V1 or V2 corresponding to the accumulated charge amount is increased to increase the voltage V1 or V2 corresponding to the accumulated charge amount within the input voltage range. In one embodiment, the charge accumulation unit 133 will be described in more detail with reference to FIG. 2.

The AD converter 140 may convert the voltage V1 or V2 output from the signal receiver 130 into a digital signal Vo and output the digital signal Vo. The digital signal Vo converted by the AD converter 140 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 260, a sensing driver 263, and a sensing signal output unit 265. The sensing controller 260 may generate and output a sensing control signal SECON in response to the digital signal Vo output from the AD converter 140. The sensing driver 263 may generate and output at least one driving signal for controlling the sensing signal output unit 265 in response to the sensing control signal SECON.

The sensing driver 263 may include at least one driver for generating at least one driving signal. For example, as illustrated in FIG. 2, the sensing driver 263 turns on or turns on the first driver DR1 and the NMOS transistor N1, which 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 263 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 265 may output the sensing signal SEN of the first voltage VH in the first logic state or the second voltage VL in the second logic state in response to the at least one driving signal. have. As illustrated in FIG. 3, the sensing signal SEN may be a sine wave signal in which a first logic state of the first voltage VH and a second logic state of the second voltage VL are repeated. For example, the sensing signal output unit 265 may include the PMOS transistor P1 and the NMOS transistor N1 connected in series between the first voltage VH and the second voltage VL, 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 the first logic state and the second logic state can be generated and output the repeated signal in the accumulating period may have a different configuration.

The capacitance sensor 120 may be modeled as a capacitor C _MUT connected between the input terminal IN and the output terminal OUT, and outputs an amount of charge of Q or Q + ΔQ through the output terminal OUT according to a touch state. Can be.

The sampling unit 131 may include a first sampling switching unit 210 and a second sampling switching unit 220 to sample the amount of charge output from the capacitance sensor 120. The first sampling switching unit 210 may connect or disconnect the output terminal of the capacitance sensor 120 and the ground voltage source VSS in response to the first sampling control signal SCON1. The second sampling switching unit 220 may sample and output the amount of charge output from the capacitance sensor 120 to the output of the sampling unit 131 in response to the second sampling control signal SCON2. That is, the second sampling switching unit 220 may connect or block the output terminal of the capacitance sensor 120 and the input terminal of the charge accumulation unit 133 in response to the second sampling control signal SCON2. The first sampling switching unit 210 and the second sampling switching unit 220 are selectively operated, and the signal receiving unit 130 is described with respect to the operations of the first sampling switching unit 210 and the second sampling switching unit 220. It will be described in more detail while explaining the overall operation of.

The charge accumulation unit 133 may include the operational amplifier 250, the initialization switching unit 230, the plurality of capacitors C1, ..., Cn, and the plurality of gain control switching units 240_1, ..., 240_n. It can be provided. The operational amplifier 250 converts the input terminal (-) connected to the output terminal of the sampling unit, the ground voltage input terminal (+) connected to the ground voltage source VSS, and the voltage V1 or V2 corresponding to the accumulated charge amount to the AD converter 140. It may include an output terminal for outputting. The initialization switching unit 230 may connect or disconnect the input terminal (−) and the output terminal of the operational amplifier 250 in response to the initialization signal RST. That is, when the touch state of the touch panel is changed or when the charge amount is sampled and accumulated n times, the initialization switching unit 230 connects an input terminal (−) and an output terminal of the operational amplifier 250 to the accumulated charge amount. The corresponding voltage V1 or V2 can be initialized.

Capacitors C1, ..., Cn are connected in parallel between the input terminal (-) and the output terminal of the operational amplifier 250, and corresponding gain control switching among the gain control switching units 240_1, ..., 240_n. It may be connected between the input terminal (−) of the additional operational amplifier 250 and the corresponding capacitor or between the output terminal of the operational amplifier 250 and the corresponding capacitor. That is, each of the gain control switching units 240_1, ..., 240_n may correspond to an input terminal (−) of the operational amplifier 250 in response to a corresponding gain control signal among the gain control signals GCON_1,..., CGCON_n. Corresponding capacitors can be connected or disconnected between output stages. That is, the number of capacitors connected between the input terminal (−) and the output terminal of the operational amplifier 250 using the gain control signals GCON_1,..., CGCON_n and the gain control switching units 240_1,..., 240_n. By adjusting, the amount of charges sampled by the sampling unit 131 may be accumulated and gain may be adjusted.

As the capacitance sum of the capacitors connected between the input terminal (-) and the output terminal of the operational amplifier 250 decreases, the voltage V1 or V2 output from the charge accumulation unit 133 increases, and the input terminal of the operational amplifier 250 ( As the capacitance sum of the capacitors connected between-) and the output terminal increases, the voltage V1 or V2 output from the charge accumulation unit 133 decreases. Accordingly, as the number of gain control switching units turned on among the gain control switching units 240_1, ..., 240_n is adjusted using the gain control signals GCON_1,..., CGCON_n, the charge accumulation unit ( The voltage V1 or V2 output from the 133 may be increased or decreased. That is, the gain control unit 135 may increase the voltage V1 or V2 output from the charge accumulation unit 133 by using the digital signal Vo output from the AD converter 140. Gain control signals GCON_1,..., GCON_n are generated to reduce the number of the capacitors connected between the input terminal (−) and the output terminal, and use the digital signal Vo output from the AD converter 140. In order to lower the voltage V1 or V2 output from the charge accumulation unit 133, the gain control signals may be increased to increase the number of the capacitors connected between the input terminal (−) and the output terminal of the operational amplifier 230. GCON_1, ..., GCON_n) can be generated and printed. As described above, as the gain control switching units 240_1, ..., 240_n are turned on or off in response to the generated gain control signals GCON_1,..., GCON_n, the charge accumulation unit 133 The amount of charges sampled by the sampling unit 131 may be accumulated and gain may be adjusted to generate and output a voltage V1 or V2 corresponding to the amount of accumulated charge.

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 when the charge amount is sampled and accumulated n times The initialization signal RST is changed from the first logic state to the second logic state so that the initialization switch 230 is turned on. In this case, since the input terminal (−) and the output terminal of the operational amplifier 250 are directly connected, the output of the charge accumulation unit 133 is initialized to the ground voltage. Afterwards, the capacitance sensor 120 outputs an amount of charge according to the touch state of the touch panel in response to the sensing signal SEN. As described above, the capacitance sensor 120 may output a charge amount of Q when the conductor does not touch the touch panel, and output a charge amount of Q + ΔQ when the conductor touches the touch panel.

The time point at which the sensing signal SEN is changed from the first logic state to the second logic state is a time point at which the charge amount output from the capacitance sensor 120 is sampled, and the signal receiver 133 samples and accumulates the charge amounts. The time point at which the sensing signal SEN is changed from the first logic state to the second logic state is the same as the time point at which the second sampling control signal SCON_2 is changed from the first logic state to the second logic state. That is, the sensing signal SEN and the second sampling control signal SCON_2 have the same phase in the period in which the signal receiver 133 samples and accumulates the charges, and the first sampling control signal CON_1 and the second sampling control have the same phase. Signal SCON_2 may have an opposite phase.

That is, when the first sampling control signal SCON_1 is in the second logic state and the second sampling control signal SCON_2 is in the first logic state, the first sampling switching unit 210 is turned on and the second sampling switching unit ( 220 is turned off so that the output of the capacitance sensor 120 is connected to the ground voltage source (VSS) and does not sample the charge amount. When the first sampling control signal SCON_1 is in the first logic state and the second sampling control signal SCON_2 is in the second logic state, the first sampling switching unit 210 is turned off and the second sampling switching unit 220 is turned on. When turned on, the output of the capacitance sensor 120 may be input to the charge accumulation unit 133 to sample the 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 performs sampling at four times when the second sampling control signal SCON_2 is changed from the first logic state to the second logic state, and the charge accumulation unit 133 samples the fourth time. Accumulated charge amounts may be accumulated and a gain may be adjusted to output a voltage V1 or V2 corresponding to the accumulated charge amount. Since the method of accumulating the sampled charge amounts and adjusting the gain has been described in detail above, detailed description thereof will be omitted. When the charge accumulation unit 133 outputs the voltage V1 or V2 corresponding to the accumulated charge amount, the ADC enable signal ADC_EN is changed from the first logic state to the second logic state so that the AD converter 140 is turned on. When enabled, the AD converter 140 changes the voltage V1 or V2 corresponding to the accumulated charge amount into a digital signal. As described above, when sampling and accumulating at four times and adjusting gain are performed, the initialization signal RST is changed from the first logic state to the second logic state, and the initialization switch 230 is turned on to operate the operational amplifier 250. Since the input terminal (-) and the output terminal are directly connected, the output of the charge accumulation unit 133 is initialized to the ground voltage.

In the above, the case where the sensing signal SEN, the first sampling control signal SCON1, and the second sampling control signal SCON2 have the waveform shown in FIG. 3 has been described. However, the sensing signal SEN, the first sampling control signal SCON1 and the second sampling control signal SCON2 do not necessarily have a waveform as shown in FIG. 3, and other waveforms may be operated as described above. May have For example, like the second sampling control signal SCON2 of FIG. 3, the sensing signal SEN may have a waveform that toggles n times only in a section in which an amount of charge is sampled and accumulated.

By the above operation, the voltage V1 or V2 output from the charge accumulation unit 133 may be expressed by Equation 1 below.

In Equation 1, C _F refers to the sum of capacitances of capacitors connected between an input terminal (−) and an output terminal of the associating amplifier 250 among the capacitors C1,..., Cn. That is, in the state where the conductor is not touched by the touch panel, the voltage V1 is a voltage corresponding to the charge amount obtained by accumulating the charge quantity Q n times and adjusting the gain, and the voltage (V) when the conductor is touched by the touch panel. V2) may be a voltage corresponding to the charge amount obtained by accumulating the charge amount Q + ΔQ and adjusting gain.

4 is a view for explaining a change in the amount of charge according to the touch state of the conductor when the capacitance sensor 120 of FIG. 1 according to an embodiment.

1 to 4, the capacitance sensor 120 of FIG. 4 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. 5 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 5, unlike the capacitance sensor of FIG. 5, the capacitance sensor 120 of FIG. 5 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 structure of the capacitance sensor 120 of FIGS. 4 and 5 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. 4 and 5. 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.

FIG. 6 is a diagram illustrating a difference between noise when amplifying the sensed charge amount and accumulating the sensed charge amount.

1 to 6, in the case of simply amplifying the amount of charge sensed by the capacitance sensor, the noise is amplified by an amplification ratio (A), but the amount of charge sensed by the capacitance sensor 120 according to an embodiment of the present invention. In the case of sampling and accumulating, the positive and negative components of the noise are canceled by accumulation, and the noise has an average value. Therefore, compared to the case of simply amplifying the sensed charge amount, according to an embodiment of the inventive concept, the signal to noise ratio (SNR) may be improved by minimizing noise.

7 is a flowchart illustrating a method of detecting a charge amount of a touch panel according to an exemplary embodiment of the inventive concept.

1 to 7, the signal transmission unit 110 may generate and output a sensing signal SEN including information on a sampling time point (S710). The capacitance sensor 120 may receive the sensing signal SEN and output a charge amount Q or Q + ΔQ according to the touch state of the touch panel in response to the received sensing signal SEN (S720). The sampling unit 131 of the signal receiving unit 130 outputs an amount of charge output from the capacitance sensor 120 in response to the first sampling control signal SCON1 and the second sampling control signal SCON2 including information on the number of sampling times. Q or Q + ΔQ) is sampled n times, and the charge amount accumulator 133 accumulates the sampled charge amounts n times in response to a plurality of gain control signals GCON and adjusts the gain to remove noise and gain. The voltage V1 or V2 corresponding to the adjusted cumulative charge amount may be output (S730). The AD converter 140 may convert the voltage V1 or V2 output from the charge accumulation unit 133 into a digital signal Vo and output the digital signal Vo (S740). Regarding each step, since it has been described in detail with reference to FIGS. 1 to 6, it will be omitted below.

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;
A capacitance sensor comprising an input terminal for receiving the sensing signal and an output terminal for outputting a charge amount according to a touch state of the touch panel in response to the received sensing signal;
A signal receiver configured to sample and accumulate the charge amount output from the capacitance sensor n times (n is a natural number) and adjust gain to output a voltage corresponding to the accumulated charge amount with noise removed and gain adjusted; And
And an AD (analog to digital) converter converting the voltage output from the signal receiver into a digital signal and outputting the digital signal.
The signal transmission unit,
The signal receiving unit generates and outputs the sensing signal in which a first logic state and a second logic state are repeated in a section in which the charge amounts are sampled and accumulated,
Wherein the signal receiver comprises:
Sampling the amount of charges output from the capacitance sensor when the sensing signal changes from the first logic state to the second logic state
Charge detector of touch panel. The method of claim 1, wherein the signal receiving unit,
A gain controller configured to generate and output a plurality of gain control signals using the digital signal output from the AD converter;
A sampling unit for sampling the charge amounts output from the capacitance sensor n times in response to the first sampling control signal and the second sampling control signal including information about the number of sampling; And
And a charge accumulation unit configured to accumulate the n-sampled charge amounts in response to the gain control signals, and adjust a gain to output a voltage corresponding to the accumulated charge amount. The method of claim 2, wherein the sampling unit,
A first sampling switching unit connecting or disconnecting an output terminal of the capacitance sensor and a ground voltage source in response to the first sampling control signal; And
A second sampling switching unit configured to sample and output an amount of charge output from the capacitance sensor in response to the second sampling control signal,
And the first sampling switching unit and the second sampling switching unit operate selectively. The method of claim 3, 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 charge amounts;
The second sampling control signal,
A signal having the same phase as the sensing signal in a section in which the signal receiver samples and accumulates the charge amounts;
The first sampling control signal,
The charge amount sensing device of the touch panel, characterized in that the signal having a phase opposite to the second sampling control signal. The method of claim 4, wherein the first sampling switching unit,
In the period in which the signal receiving unit samples and accumulates the charge amounts, when the first sampling control signal is in a first logic state, a ground voltage source is connected to an output terminal of the capacitance sensor, and the first sampling control signal is in a second logic state. If the ground voltage source and the output terminal of the capacitance sensor is disconnected,
The second sampling switching unit,
In the period in which the signal receiving unit samples and accumulates the charge amounts, when the second sampling control signal is in a first logic state, the output terminal of the capacitance sensor and the input terminal of the charge amount accumulation unit are disconnected, and the second sampling control signal is In the second logic state, the amount of charge sensing device of the touch panel, characterized in that for connecting the output terminal of the capacitance sensor and the input terminal of the charge accumulation unit. The method of claim 2, wherein the charge amount accumulator,
An 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 a voltage corresponding to the accumulated charge amount to the AD converter;
When the touch state of the touch panel is changed or when the charge amount is sampled and accumulated n times, an initialization switching unit for initializing the voltage corresponding to the accumulated charge amount by connecting the input terminal and the output terminal of the operational amplifier in response to an initialization signal ;
A plurality of capacitors connected in parallel between an input terminal and an output terminal of the operational amplifier; And
A plurality of gain control switching units for connecting or disconnecting each of the capacitors between an input terminal and an output terminal of the operational amplifier in response to a corresponding gain control signal among the gain control signals; Device. The method of claim 6, wherein the gain control unit,
When the voltage corresponding to the accumulated charge amount is to be increased, the number of the capacitors connected between the input terminal and the output terminal of the operational amplifier is decreased, and when the voltage corresponding to the accumulated charge amount is to be decreased, the input terminal and the output terminal of the operational amplifier are reduced. And generating the gain control signals to increase the number of the capacitors connected therebetween. delete 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. Generating and outputting a sensing signal including information on a sampling time point;
Receiving the sensing signal and outputting a charge amount according to a touch state of a touch panel in a capacitance sensor in response to the received sensing signal;
Sampling the charge amounts output from the capacitance sensor n times (n is a natural number) in response to the first sampling control signal and the second sampling control signal including information about the number of sampling;
Accumulating the n-times sampled charge amounts in response to a plurality of gain control signals and adjusting a gain to output a voltage corresponding to the accumulated charge amount in which noise is removed and the gain is adjusted; And
And converting the voltage into a digital signal and outputting the converted digital signal.
The sensing signal is,
A first logic state and a second logic state are repeated in a section in which the signal receiver samples and accumulates the charge amounts;
The second sampling control signal,
A signal having the same phase as the sensing signal in a period in which the charge amounts are sampled and accumulated;
The first sampling control signal,
Characterized in that the signal having a phase opposite to the second sampling control signal
How to detect charge on touch panel. delete The method of claim 10, wherein the sampling comprises:
Applying an amount of charge output from the capacitance sensor to an input of an operational amplifier in response to the second sampling control signal at points in time when the sensing signal is changed from the first logic state to the second logic state; And
Applying a ground voltage to an input terminal of the operational amplifier in response to the first sampling control signal at points in time when the sensing signal is changed from the second logic state to the first logic state,
The step of outputting a voltage corresponding to the accumulated charge amount,
The amount of sampled charge is controlled by adjusting the number of capacitors connected in parallel between an input terminal of an associative amplifier to which the n sampled charge amounts are applied and an output terminal of the operational amplifier in response to the gain control signals generated using the digital signal. Accumulating n times and adjusting a gain to output a voltage corresponding to the accumulated charge amount. The method of claim 12, wherein the charge amount sensing method of the touch panel includes:
When the touch state of the touch panel changes or when the charge amount is sampled and accumulated n times, connecting the input terminal and the output terminal of the operational amplifier to initialize the voltage corresponding to the accumulated charge amount in response to an initialization signal. Charge amount sensing method of the touch panel characterized in that it comprises. The method of claim 12, wherein the outputting the voltage corresponding to the accumulated charge amount comprises:
The cumulative charge amount is increased by reducing the number of capacitors connected between the input terminal and the output terminal of the operational amplifier to increase the voltage corresponding to the accumulated charge amount, or increasing the number of the capacitors connected between the input terminal and the output terminal of the operational amplifier. And adjusting the gain by lowering a voltage corresponding to the charge amount of the touch panel.

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