KR102417379B1 - Touch sensing controller and touch sensing device having the same - Google Patents

Abstract

Disclosed are a touch sensing controller for determining whether a touch occurs based on sensing signals differentially received from sensing electrodes adjacent to each other, and a touch sensing device having the same. The touch sensing device includes: a touch panel on which a plurality of driving electrodes and a plurality of sensing electrodes are disposed; and a driving unit that provides a plurality of driving signals having different frequencies to the driving electrodes, and a sensing unit that differentially receives sensing signals sensed through the sensing electrodes to determine whether a touch occurs. Including, wherein the sensing unit includes a plurality of current conveyor circuits for generating differential sensing signals by differentially receiving the sensing signals, wherein the number of the current conveyor circuits is one less than the number of the sensing electrodes . Accordingly, it is possible to differentially receive sensing signals from adjacent sensing electrodes and determine whether a touch occurs based on information obtained through fast Fourier transform.

Description

A touch sensing controller and a touch sensing device having the same

The present invention relates to a touch sensing controller and a touch sensing device having the same, and more particularly, to a touch sensing controller for determining whether a touch occurs based on sensing signals differentially received from sensing electrodes adjacent to each other, and touch sensing having the same It's about the device.

Touch sensing devices allow users to conveniently interface with electronic systems and displays by reducing or eliminating the need for mechanical buttons, keypads, keyboards, and pointing devices. For example, a user may execute a complex series of commands by simply touching a touch screen being displayed at a location identified by an icon.

For example, there are several types of technologies for implementing a touch sensing device, including a resistive method, an infrared method, a capacitive method, a surface acoustic wave method, an electromagnetic method, a near field imaging method, and the like. Capacitive touch sensing devices have been found to work well in a number of applications. In many touch sensing devices, input is sensed when a conductive object within the sensor is capacitively coupled with a conductive touch tool, such as a user's finger. In general, whenever two electrically conductive members come into proximity to each other without actually touching them, a capacitance is formed between them. In the case of a capacitive touch sensing device, when an object such as a finger approaches a touch sensing surface, a small capacitance is formed between the object and a sensing point in close proximity. By detecting the change in capacitance at each sensing point and noting the location of the sensing point, the sensing circuit can recognize multiple objects and determine the properties of the objects as they move across the touch surface.

There are two known techniques used to capacitively measure touch.

One technique is to measure the capacitance to ground, whereby a signal is applied to the electrode. A touch in proximity to an electrode causes a signal current to flow from the electrode through an object such as a finger to electrical ground.

Another technique is by mutual capacitance. A mutual capacitive touch screen applies a signal to a driving electrode that is capacitively coupled to the sensing electrode by an electric field. Signal coupling between the two electrodes is reduced by a nearby object, which reduces capacitive coupling.

Korean Patent Application Laid-Open No. 2012-0095376 (Title: Multi-touch touch device having multiple driving frequencies and maximum likelihood estimation) (published on August 28, 2012) Korean Patent Laid-Open Patent No. 2011-0134886 (Title: Multi-function capacitance sensing circuit with current conveyor) (published on December 15, 2011)

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to differentially receive sensing signals from adjacent sensing electrodes to determine whether touch occurs based on information obtained through fast Fourier transform. It is to provide a touch sensing controller that determines

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Another object of the present invention is to provide a touch sensing device having the above-described touch sensing controller.

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In order to achieve the above object of the present invention, a touch sensing controller according to an embodiment includes a driver providing a plurality of driving signals having different frequencies to a plurality of driving electrodes; and a sensing unit that differentially receives sensing signals sensed through a plurality of sensing electrodes to determine whether a touch occurs, wherein the sensing unit receives the sensing signals differentially to generate differential sensing signals. circuits, wherein the number of the current conveyor circuits is smaller than the number of the sensing electrodes by one.

In an embodiment, the driving unit may include a digital function generator that provides a sine wave to each of the driving electrodes.

In one embodiment, the touch sensing controller further includes a touch driving control unit, and the digital function generator is connected to each of the driving electrodes to generate a sine wave precisely in response to the control of the touch driving control unit with an accurate frequency, period and phase. It may include a plurality of Direct Digital Synthesis (DDS) modules configured to generate.

In an embodiment, the touch sensing controller may further include a noise sensing unit that senses a surrounding noise component and provides a frequency characteristic of the sensed noise component to the touch driving controller.

In an embodiment, the touch driving control unit may control the driving unit to generate the driving signal by avoiding a frequency band of a noise component provided by the noise sensing unit.

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In an embodiment, the odd-numbered current conveyor circuit includes a first input terminal connected to the odd-numbered sensing electrode and a second input terminal connected to the even-numbered sensing electrode, and the even-numbered current conveyor circuit includes a first input terminal connected to the even-numbered sensing electrode. It may include an input terminal and a second input terminal connected to the odd-numbered sensing electrode.

In an embodiment, the sensing unit may include: a first signal amplifier including a plurality of signal amplifiers connected to respective output terminals of the current conveyor circuit, and first amplifying a sensing signal output from each of the current conveyor circuits; an active filter unit including a plurality of active filters connected to an output terminal of each of the signal amplifiers and filtering each of the amplified sensing signals; a second signal amplifier comprising a plurality of signal amplifiers connected to each of the output terminals of the active filters, and second amplifying the active filtered sensing signals; an analog-to-digital converter including a plurality of analog-to-digital converters and digitally converting each of the second amplified sensing signals; a fast Fourier transform unit including a plurality of fast Fourier transforms and fast Fourier transforming each of the digitally converted sensing signals; and a touch determination unit configured to determine whether a touch occurs based on an amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal.

In order to achieve the above object of the present invention, a touch sensing controller according to another embodiment includes a driver providing a plurality of driving signals having different frequencies to a plurality of driving electrodes; and a sensing unit that differentially receives sensing signals sensed through a plurality of sensing electrodes to determine whether a touch occurs, wherein the sensing unit receives the sensing signals differentially and generates the differential sensing signals. Conveyor circuits may be included. Here, the number of the current conveyor circuits may be the same as the number of the sensing electrodes.

In an embodiment, the odd-numbered current conveyor circuit may be connected to the odd-numbered sensing electrode, and the even-numbered current conveyor circuit may be connected to the even-numbered sensing electrode.

In an embodiment, the sensing unit may include: a first signal amplifier including a plurality of signal amplifiers connected to respective output terminals of adjacent current conveyor circuits, and first amplifying a sensing signal output from each of the current conveyor circuits; an active filter unit including a plurality of active filters connected to an output terminal of each of the signal amplifiers and filtering each of the amplified sensing signals; a second signal amplifier comprising a plurality of signal amplifiers connected to each of the output terminals of the active filters, and second amplifying the active filtered sensing signals; an analog-to-digital converter including a plurality of analog-to-digital converters and digitally converting each of the second amplified sensing signals; a fast Fourier transform unit including a plurality of fast Fourier transforms and fast Fourier transforming each of the digitally converted sensing signals; and a touch determination unit configured to determine whether a touch occurs based on an amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal.

In one embodiment, the current conveyor circuit connected to the first sensing electrode includes a first floating output terminal and a second output terminal connected to the first signal amplifier, and the current conveyor circuit connected to the last sensing electrode is a first output terminal connected to the last signal amplifier. It may include an output terminal and a floating second output terminal.

In an embodiment, the active filter unit may include any one of a low-pass filter and a band-pass filter.

In an embodiment, the touch sensing controller includes touch sensing for controlling operations of the current conveyor circuit, the first signal amplifier, the active filter unit, the second signal amplifier, the analog-to-digital converter, and the fast Fourier transform unit. It may further include a control unit.

In an embodiment, the touch sensing control unit may provide information on the frequency of the driving signal to the analog-to-digital converter so that the analog-to-digital converter converts the analog-to-digital signal to a frequency faster than the frequency of the driving signal. .

In order to realize another object of the present invention, a touch sensing device according to an embodiment includes a touch panel on which a plurality of driving electrodes and a plurality of sensing electrodes are disposed; and a driving unit that provides a plurality of driving signals having different frequencies to the driving electrodes, and a sensing unit that differentially receives sensing signals sensed through the sensing electrodes to determine whether a touch occurs. Including, wherein the sensing unit includes a plurality of current conveyor circuits for generating differential sensing signals by differentially receiving the sensing signals, wherein the number of the current conveyor circuits is equal to or smaller than the number of the sensing electrodes by one do it with

According to such a touch sensing controller and a touch sensing device having the same, it is possible to differentially receive sensing signals from adjacent sensing electrodes and determine whether a touch occurs based on information obtained through fast Fourier transform.

1A and 1B are block diagrams for explaining a touch sensing device according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a symbol of the current conveyor circuit shown in FIG. 1A.
FIG. 3 is a circuit diagram for explaining an example of the current conveyor circuit shown in FIG. 2 .
4 is a configuration diagram schematically illustrating a touch sensing device according to a comparative example.
5A to 5C are graphs for schematically explaining a touch sensing method through the touch sensing device according to the comparative example shown in FIG. 4 .
6 is a configuration diagram schematically illustrating a touch sensing device according to the present invention.
7A to 7C are graphs for schematically explaining a touch sensing method through the touch sensing device shown in FIG. 6 according to the present invention.
8A and 8B are block diagrams for explaining a touch sensing device according to another embodiment of the present invention.
FIG. 9A is a diagram for explaining a symbol of the current conveyor circuit shown in FIG. 8A , and FIG. 9B is an equivalent circuit diagram for explaining the current conveyor circuit shown in FIG. 8A .
10 is a circuit diagram for explaining an example of the current conveyor circuit shown in FIG. 8A.
11A and 11B are block diagrams for explaining a touch sensing device according to another embodiment of the present invention.
12 is a frequency noise spectrum for explaining charger noise generated in a mobile phone employing a touch sensing device.
13 is a frequency noise spectrum for explaining the setting of a driving frequency in the frequency noise spectrum of FIG. 12 .

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged than the actual size for clarity of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

1A and 1B are block diagrams for explaining a touch sensing device according to an embodiment of the present invention.

1A and 1B , the touch sensing apparatus 100 according to an embodiment of the present invention includes a touch panel 110 and a touch sensing controller 120 .

The touch panel 110 includes a plurality of driving electrodes 112 for transmitting a driving signal and a plurality of sensing electrodes 114 for transmitting a sensing signal. The driving electrodes 112 and the sensing electrodes 114 may be disposed on different layers. 1 shows that the driving electrodes 112 are disposed on the lower layer and the sensing electrodes 114 are disposed on the upper layer, but the reverse is also possible. The driving electrodes 112 and the sensing electrodes 114 may be arranged in a matrix type when viewed in a plan view. Meanwhile, the driving electrodes 112 and the sensing electrodes 114 may be disposed on the same layer. For example, the driving electrodes 112 and the sensing electrodes 114 may be alternately disposed with each other.

The touch panel 110 is typically substantially transparent to allow a user to view an object (such as a pixelated display of a computer, handheld device, cell phone, or other peripheral device) through the touch panel 110 .

For convenience of description, the driving electrodes 112 and the sensing electrodes 114 are shown to be wide and well visible, but in reality they are relatively narrow and may be invisible to the user. In addition, the driving electrodes 112 and the sensing electrodes 114 have a variable width - for example, increase the inter-electrode fringe field, thereby increasing the driving electrodes 112 and the sensing electrodes 114 ) designed to have an increased width in the form of a diamond-shaped or other shaped pad in the vicinity of the nodes of the matrix to increase the effect of touch on the electrode-to-electrode capacitive coupling. can be

In an exemplary embodiment, the driving electrodes 112 and the sensing electrodes 114 may be made of indium tin oxide (ITO) or other suitable electrically conductive material.

The touch sensing controller 120 includes a driving unit 122 , a sensing unit 124 , and a control unit 126 . In operation, the touch sensing controller 120 provides a plurality of driving signals having different driving frequencies to the driving electrodes 112 , and fast Fourier transforms the sensing signals sensed by each of the sensing electrodes 114 . (FFT) to determine whether a touch occurs based on the amount of change in the magnitude of the sensing frequency with respect to the driving frequency.

The driving unit 122 simultaneously provides driving signals having different driving frequencies to each of the driving electrodes 112 . For example, a driving signal having a first frequency f0 is provided to the first driving electrode, a driving signal having a second frequency f1 is provided to the second driving electrode, and a third frequency is provided to the third driving electrode. A driving signal having (f2) is provided, and a driving signal having a fourth frequency (f3) is provided to the fourth driving electrode. The driving signals having the different driving frequencies may be generated under the control of the controller 126 . In this embodiment, the driving signals may include a sine wave such as a sine wave or a cosine wave. In this embodiment, the driving signals may start at different phases. In the present embodiment, since the driving unit 122 drives the driving electrodes 112 at the same time using driving signals having different driving frequencies, the touch sensing time is fast and thus a high-speed response is possible.

In this embodiment, the driving unit 122 may include a digital function generating unit that provides a sine wave to each of the driving electrodes. The digital function generator is connected to each of the driving electrodes and configured to precisely generate a sine wave with an accurate frequency, period and phase in response to the control of the touch driving controller. ) modules.

The sensing unit 124 includes a differential receiving unit 410 , a first signal amplifying unit 420 , an active filter unit 430 , a second signal amplifying unit 440 , an analog-to-digital converting unit 450 , and a fast Fourier transform. It includes a unit 460 and a touch determination unit 470 .

The sensing unit 124 differentially receives a sensing signal from each of the sensing electrodes 114 to generate a differential sensing signal, and fast Fourier transforms the differential sensing signal to obtain a frequency magnitude of the differential sensing signal, It is determined whether or not a touch occurs based on the amount of change between the frequency magnitude of the sensing signal and the frequency magnitude of the driving signal.

That is, the touched electrode is received in a form in which the amplitude of the sinusoidal wave applied to the corresponding electrode is reduced. The frequency of the attenuated sine wave is detected and amplified by the differential receiver 410, so the amplitude (Magnitude) value of the FFT result corresponding to the driving frequency of the sensor where the touch occurs increases by the amount of signal change generated by the touch.

The differential receiver 410 is connected to each of the sensing electrodes 114 to receive sensing signals of the sensing electrodes adjacent to each other. The differential receiver 410 may include a plurality of current conveyor circuits. Each of the current conveyor circuits differentially receives the sensing signals to generate the differential sensing signal and provides the generated differential sensing signal to the signal amplifier 430 . In this embodiment, the current conveyor circuit may be a differential current conveyor circuit.

The first signal amplifier 420 includes a plurality of first signal amplifiers, amplifies the differential sensing signal output from the differential receiver 410 and provides the amplified signal to the active filter unit 430 . In this embodiment, the first signal amplifiers may include a differential amplifier.

The active filter unit 430 actively filters each of the amplified sensing signals and provides them to the analog-to-digital conversion unit 450 . The active filter unit 430 may include a plurality of band pass filters. Meanwhile, the active filter unit 430 may include a plurality of low pass filters.

That is, the receiving end may use a band pass filter to set the frequency band of the input signal to the driving frequency band of interest. Alternatively, low-pass filters may be used because low-frequency components can be distinguished by the FFT according to the resolution of the fast Fourier transform (FFT). Alternatively, the amplifier stage can be directly connected without a low-pass filter by using the high-frequency cutoff frequency component of the current conveyor and the voltage amplifier.

The second signal amplifier 440 includes a plurality of second signal amplifiers, amplifies the active filtered sensing signals and provides them to the analog-to-digital converter 450 . In this embodiment, the second signal amplifiers may include a differential amplifier.

The analog-to-digital converter 450 includes a plurality of analog-to-digital converters, digitally converts each of the active-filtered sensing signals, and provides them to the fast Fourier transform unit 460 . The analog-to-digital converter 450 performs ADC conversion at a frequency that is at least two times faster than the driving frequency. Information on the driving frequency may be provided from the controller 126 . In this embodiment, the analog-to-digital converter may include a differential analog-to-digital converter (differential ADC).

The fast Fourier transform unit 460 includes a plurality of fast Fourier transforms, and performs fast Fourier transform on each of the digitally converted sensing signals to convert each of the sensed signals from a time domain to a frequency domain. to obtain the frequency component and the magnitude of the frequency component, and then provide it to the touch determination unit 470 . In this embodiment, it is very useful for digital signal processing by converting sensing in the time domain into sensing in the frequency domain.

The touch determination unit 470 determines whether a touch occurs based on the amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal. Information on the frequency of the driving signal may be provided from the controller 126 .

The control unit 126 includes a touch driving control unit 127 and a touch sensing control unit 128 .

The touch driving control unit 127 controls the operation of the driving unit 122 to simultaneously provide driving signals having different driving frequencies to each of the driving electrodes 112 .

The touch sensing control unit 128 converts the information about the frequency of the driving signal to the analog-to-digital converter 450 so that the analog-to-digital converter 450 converts the analog-to-digital to a frequency faster than the frequency of the driving signal. provided to

The touch sensing controller 120 may further include one or more memory devices (not shown) for storing the measured size and associated parameters, and a microprocessor (not shown) for performing necessary calculation and control functions.

The touch sensing controller 120 and/or other parts of the touch sensing device 100 may include one or more application-specific integrated circuits (ASICs), ASSPs, to perform one or more of the functions described herein. (application-specific standard product), etc. may be implemented.

As described above, for driving and sensing the touch screen, driving signals having different transmission frequencies having a sine wave in the frequency domain are simultaneously transmitted to the driving electrode of the touch panel, and between the signals received from the sensing electrode After extracting and amplifying only a differential component, that is, a touch change amount, Fast Fourier Transform (FFT) is performed to determine the change amount as touch sensitivity.

In addition, by changing and using the transmission frequency in real time through the above method and noise spectrum analysis, touch driving and sensing speed and touch sensitivity can be improved, and resistance to noise can also be improved.

In addition, according to the present invention, by disposing a differential receiver at each end of each of the sensing electrodes to sense a touch through a known change in gain of a transmission frequency component, there are advantages as follows.

It is easy to distinguish a noise component having a frequency component and a touch component. Accordingly, since it is possible to measure only the amount of change in a received signal of a desired frequency using the result of FFT without additional processing on a noise component generated in the operating environment of the touch screen, it is easy to solve the noise.

By driving a plurality of driving electrodes at the same time, the touch sensing time is fast, and a high-speed response is easy.

Since sensing in the time domain is sensed in the frequency domain, it is very useful for digital signal processing.

Since the driving frequency of the sensor is close to the time constant of the sensor or it can be driven faster in consideration of the attenuation, it is very advantageous for driving a high-resistance sensor (eg, a mid-to-large sized touch panel or single-sided sensor).

FIG. 2 is a diagram for explaining a symbol of the current conveyor circuit 412 shown in FIG. 1A. 3 is a circuit diagram for explaining an example of the current conveyor circuit 412 shown in FIG.

2 and 3, a current conveyor circuit 412 is a device having five terminals obtained by interconnecting voltage and current followers.

The five terminals of the current conveyor circuit are a voltage input terminal (Y), a first current input terminal (X1), a second current input terminal (X2), a first current output terminal (Z1), and a second current output terminal (Z2) ) is included.

The implementation of the bipolar current output of the current conveyor circuit contributes to noise reduction and can be used to build a quasi-differential channel.

The first current output terminal Z1 is a high impedance output terminal suitable for current output. The direction of the first output current IZ1 is proportional to the input current at the first current input terminal X1 . The input-output relationship of the current conveyor circuit can be described by the following matrix equation.

[Equation 1]

Using a current conveyor circuit to sense capacitance at multiple nodes of the capacitance sensing circuit described above may provide the following benefits.

First, the current conveyor circuit has a low impedance current input (XI), which can provide good immunity to high impedance noise signals such as RF or ESD.

Second, the voltage potential of the current input XI is controlled by the high-impedance voltage input YV, which realizes an optimal structure for a plurality of capacitance sensing modes (self-capacitance sensing mode and mutual capacitance sensing mode). allow

Third, the current outputs of the current conveyor circuit can be easily converted into a measurable form by using charge integration/balance circuits such as a sigma-delta modulator or simple charge integration circuits.

Finally, the current conveyor circuit can operate without an external closed loop, which provides stability at different sensor parasitic capacitances. Current conveyor circuits are extensively used within analog and mixed-signal ASICs for signal amplification, filtering and rectification, multiplication and division of analog signals, construction of transimpedance and transconductance amplifiers, and wideband line drivers. There are only a few discrete implementations of current conveyor circuits, sometimes called ideal transistors.

In one embodiment, the current conveyor circuit may be an op amp based architecture, using a closed loop system. In another embodiment, the current conveyor circuit may use the translinear principle using an open loop architecture. Alternatively, other implementations of the current conveyor circuit may be used to sense capacitance, as will be appreciated by one of ordinary skill in the art having the benefit of this disclosure.

In this embodiment, the current conveyor circuits have a first current conveyor circuit, the last current conveyor circuit, and the remaining current conveyor circuits have different asymmetric structures.

Assuming that each of the MOSFETs has the same length, the width of each of the MOSFETs has the following relationship.

In the case of the current conveyor circuit connected to the first sensing electrode, there is a relationship between M11: M13=2:1 and M12:M14=2:1. In the case of the current conveyor circuit connected to the last sensing electrode, there is a relationship between M11: M13=1:2 and M12:M14=1:2. In the case of the current conveyor circuit connected to each of the remaining sensing electrodes, M11: M13 = 1:1 and M12: M14 = 1:1.

Then, below, a method for sensing a touch using a touch sensing device according to the present invention and a method for sensing a touch using a touch sensing device according to a comparative example will be described in comparison.

4 is a configuration diagram schematically illustrating a touch sensing device according to a comparative example. 5A to 5C are graphs for schematically explaining a touch sensing method through the touch sensing device according to the comparative example shown in FIG. 4 .

4 to 5C , driving signals having different driving frequencies are sequentially provided to the touch panel. The touch panel is provided to determine whether a user touches in a capacitive manner.

The sensing signals sensed by the touch panel have a differentiated signal form.

Sensing signals in the form of differential signals are amplified and then integrated.

Coordinates of where the touch is generated are derived through the integrated sensing signals.

As such, the driving and sensing technology of the touch sensing device according to the comparative example sequentially transmits a square wave (or square wave) having a predetermined period to the driving electrode in the time domain and accumulates the differential signal of the square wave, which is the sensing signal received through the sensing electrode. /Integrated to determine whether the user's touch or not from the amount of change in the signal magnitude. Therefore, it is difficult to sense with high sensitivity and has a disadvantage in enlargement, as well as being vulnerable to noise components.

6 is a configuration diagram schematically illustrating a touch sensing device according to the present invention. 7A to 7C are graphs for schematically explaining a touch sensing method through the touch sensing device shown in FIG. 6 according to the present invention.

6 to 7C , driving signals having different driving frequencies are simultaneously provided to the touch panel. The touch panel is provided to determine whether a user touches in a capacitive manner.

The sensing signals sensed by the touch panel have a synthesized signal form.

The sensed signals in the form of a synthesized signal are amplified and then subjected to FFT processing.

The FFT-processed sensing signals are decomposed and analyzed to derive the coordinates of where the touch occurred.

As such, the driving and sensing technology of the touch sensing device according to the present invention converts signal processing into the frequency domain by applying communication theory for driving and sensing the touch screen. In addition, the touch screen signal was processed by applying a differential signal processing technique to improve the touch sensitivity.

Specifically, by applying the principle of the AM communication method, which is a traditional communication technique, each of a plurality of sine wave (sine wave) driving signals having different frequencies are simultaneously provided to the driving electrode, which is a signal transmission medium. Next, only a differential component between each receiving end, ie, a touch change amount, is extracted with respect to a sensing signal in which various frequencies are mixed, received from the sensing electrode. Then, after amplifying only the amount of touch displacement generated by the touch, FFT is performed to find the transmitted frequencies, and by measuring the amount of change in amplitude (Amplitude, Magnitude) for each frequency generated from the user's touch, the user's touch and the touch screen You can calculate the absolute coordinates of the phase. Accordingly, by changing and using the transmission frequency in real time through noise spectrum analysis, the touch driving speed, the sensing speed, and the touch sensitivity can be improved. In addition, since the noise component can avoid the frequency or minimize the influence of the sensing signal due to the noise, the touch sensitivity on the touch screen can be improved.

8A and 8B are block diagrams for explaining a touch sensing device according to another embodiment of the present invention.

8A and 8B , the touch sensing apparatus 200 according to another embodiment of the present invention includes a touch panel 110 and a touch sensing controller 220 .

Since the touch panel 110 is the same as the touch panel 110 illustrated in FIG. 1A , the same reference numerals are given and a detailed description thereof will be omitted.

The touch sensing controller 220 includes a driving unit 122 , a sensing unit 224 , and a control unit 126 . In operation, the touch sensing controller 220 provides a plurality of driving signals having different driving frequencies to the driving electrodes 112 , and fast Fourier transforms the sensing signals sensed by each of the sensing electrodes 114 . (FFT) to determine whether a touch occurs based on the amount of change in the magnitude of the sensing frequency with respect to the driving frequency.

Since the driving unit 122 is the same as the driving unit 122 shown in FIG. 1A , the same reference numerals are given and a detailed description thereof will be omitted.

The sensing unit 224 differentially receives the sensing signal from each of the sensing electrodes 114 to generate a differential sensing signal, and fast Fourier transforms the differential sensing signal to obtain the frequency magnitude of the differential sensing signal, It is determined whether a touch occurs based on the amount of change between the frequency magnitude of the sensing signal and the frequency magnitude of the driving signal.

The sensing unit 224 includes a differential receiving unit 510 , a first signal amplifying unit 520 , an active filter unit 430 , a second signal amplifying unit 440 , an analog-to-digital converting unit 450 , and a fast Fourier transform. It includes a unit 460 and a touch determination unit 470 .

The differential receiver 510 is connected to each of the sensing electrodes 114 to receive sensing signals of the sensing electrodes adjacent to each other. The differential receiver 510 may include a plurality of current conveyor circuits. Each of the current conveyor circuits receives the sensing signals to generate the differential sensing signal and provides the generated differential sensing signal to the first signal amplifier 520 . In this embodiment, the current conveyor circuit may be a single ended dual output current conveyor circuit.

The number of the current conveyor circuits is the same as the number of the sensing electrodes. Accordingly, the odd-numbered current conveyor circuit is connected to the odd-numbered sensing electrode, and the even-numbered current conveyor circuit is connected to the even-numbered sensing electrode. Also, the current conveyor circuit connected to the first sensing electrode includes a floating first output terminal and a second output terminal connected to the first signal amplifier, and the current conveyor circuit connected to the last sensing electrode includes a first output terminal connected to the last signal amplifier and a floating It may include a second output terminal.

The first signal amplifier 520 includes a plurality of first signal amplifiers, amplifies the differential sensing signal output from the differential receiver 510 and provides it to the active filter unit 430 . In this embodiment, the first signal amplifiers may include a differential amplifier.

The active filter unit 430 actively filters each of the amplified sensing signals and provides them to the analog-to-digital conversion unit 450 . The active filter unit 430 may include a plurality of band pass filters. Meanwhile, the active filter unit 430 may include a plurality of low pass filters.

The second signal amplifier 440 includes a plurality of second signal amplifiers, amplifies the active filtered sensing signals and provides them to the analog-to-digital converter 450 . In this embodiment, the second signal amplifiers may include a differential amplifier.

The analog-to-digital converter 450 includes a plurality of analog-to-digital converters, digitally converts each of the active-filtered sensing signals, and provides them to the fast Fourier transform unit 460 . The analog-to-digital converter 450 performs ADC conversion at a frequency that is at least two times faster than the driving frequency. Information on the driving frequency may be provided from the controller 126 . In this embodiment, the analog-to-digital converter may include a differential analog-to-digital converter (differential ADC).

The fast Fourier transform unit 460 includes a plurality of fast Fourier transforms, and performs fast Fourier transform on each of the digitally converted sensing signals to convert each of the sensed signals from a time domain to a frequency domain. to obtain the frequency component and the magnitude of the frequency component, and then provide it to the touch determination unit 470 . In this embodiment, it is very useful for digital signal processing by converting sensing in the time domain into sensing in the frequency domain.

The touch determination unit 470 determines whether a touch occurs based on the amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal. Information on the frequency of the driving signal may be provided from the controller 126 .

The control unit 126 includes a touch driving control unit 127 and a touch sensing control unit 128 .

The touch driving control unit 127 controls the operation of the driving unit 122 to simultaneously provide driving signals having different driving frequencies to each of the driving electrodes 112 .

The touch sensing control unit 128 converts the information about the frequency of the driving signal to the analog-to-digital converter 450 so that the analog-to-digital converter 450 converts the analog-to-digital to a frequency faster than the frequency of the driving signal. provided to

The touch sensing controller 220 may further include one or more memory devices (not shown) for storing the measured size and associated parameters, and a microprocessor (not shown) for performing necessary calculation and control functions.

FIG. 9A is a diagram for explaining a symbol of the current conveyor circuit shown in FIG. 8A , and FIG. 9B is an equivalent circuit diagram for explaining the current conveyor circuit shown in FIG. 8A . 10 is a circuit diagram for explaining an example of the current conveyor circuit shown in FIG. 8A.

9A-10, the current conveyor circuit is a device having four terminals, obtained by interconnecting voltage and current followers.

The four terminals of the current conveyor circuit include a voltage input terminal YV, a current input terminal XI, a current output terminal IZ+, and a current output terminal IZ−. The voltage input terminal YV is a high impedance terminal, whereas the current input terminal XI is a low impedance terminal. The input voltage VY applied to the voltage input terminal YV may be transferred to the voltage VX of the current input terminal XI (ie, VX = VY). Additionally, since the voltage input terminal YV is a high impedance input, no current flows to the voltage input terminal YV.

The input current I0 applied to the current input terminal XI is transferred from the output terminals IZ+ and IZ− to the output current IZ+. The output terminals IZ+ and IZ- are used for balanced current output (ie, IZ+ = -IX, IZ- = +IX).

The implementation of the bipolar current output of the current conveyor circuit contributes to noise reduction and can be used to build a quasi-differential channel.

The output terminal IZ+ is a high impedance output terminal suitable for current output. The direction of the output current IZ is proportional to the input current at the current input terminal XI. The input-output relationship of the current conveyor circuit can be described by the following matrix equation.

[Equation 2]

Using a current conveyor circuit to sense capacitance at a plurality of nodes of the capacitance sensing circuit may provide the following benefits.

First, the current conveyor circuit has a low impedance current input (XI), which can provide good immunity to high impedance noise signals such as RF or ESD.

Second, the voltage potential of the current input (XI) is controlled by the high-impedance voltage input (YV), which realizes an optimal structure for a plurality of capacitance sensing modes (self-capacitance sensing mode and mutual capacitance sensing mode). allow

Third, the current outputs of the current conveyor circuit can be easily converted into a measurable form by using charge integration/balance circuits such as a sigma-delta modulator or simple charge integration circuits.

Finally, the current conveyor circuit can operate without an external closed loop, which provides stability at different sensor parasitic capacitances. Current conveyor circuits are extensively used within analog and mixed-signal ASICs for signal amplification, filtering and rectification, multiplication and division of analog signals, building transimpedance and transconductance amplifiers, and wideband line drivers. There are only a few discrete implementations of current conveyor circuits, sometimes called ideal transistors.

In one embodiment, the current conveyor circuit may be an op amp based architecture, using a closed loop system. In another embodiment, the current conveyor circuit may use the translinear principle using an open loop architecture. Alternatively, other implementations of the current conveyor circuit may be used to sense capacitance, as will be appreciated by one of ordinary skill in the art having the benefit of this disclosure.

11A and 11B are block diagrams for explaining a touch sensing device according to another embodiment of the present invention.

11A and 11B , a touch sensing apparatus 300 according to another embodiment of the present invention includes a touch panel 110 and a touch sensing controller 320 .

Since the touch panel 110 is the same as the touch panel 110 illustrated in FIG. 1A , the same reference numerals are given and a detailed description thereof will be omitted.

The touch sensing controller 320 includes a driving unit 122 , a sensing unit 224 , and a control unit 126 . In operation, the touch sensing controller 320 provides a plurality of driving signals having different driving frequencies to the driving electrodes 112 , and fast Fourier transforms the sensing signals sensed by each of the sensing electrodes 114 . (FFT) to determine whether a touch occurs based on the amount of change in the magnitude of the sensing frequency with respect to the driving frequency.

Since the driving unit 122 is the same as the driving unit 122 shown in FIG. 1A , the same reference numerals are given and a detailed description thereof will be omitted.

The sensing unit 124 includes a differential receiving unit 410 , a first signal amplifying unit 420 , an active filter unit 430 , a second signal amplifying unit 440 , an analog-to-digital converting unit 450 , and a fast Fourier transform. It includes a unit 460 , a touch determination unit 470 , and a noise sensing unit 480 .

The sensing unit 124 differentially receives a sensing signal from each of the sensing electrodes 114 to generate a differential sensing signal, and fast Fourier transforms the differential sensing signal to obtain a frequency magnitude of the differential sensing signal, It is determined whether or not a touch occurs based on the amount of change between the frequency magnitude of the sensing signal and the frequency magnitude of the driving signal. In this embodiment, the differential receiving unit 410, the first signal amplifying unit 420, the active filter unit 430, the second signal amplifying unit 440, the analog-to-digital conversion unit 450, Since the fast Fourier transform unit 460 and the touch determination unit 470 are shown in FIGS. 1A and 1B , the same reference numerals are assigned to them, and detailed descriptions thereof are omitted.

The noise sensing unit 480 senses a surrounding noise component and provides a frequency characteristic of the sensed noise component to the control unit 126 . The noise component may be a charger noise component generated in the mobile phone or a noise component generated by ambient artificial light.

The control unit 126 includes a touch driving control unit 127 and a touch sensing control unit 128 .

The touch driving control unit 127 controls the operation of the driving unit 122 to simultaneously provide driving signals having different driving frequencies to each of the driving electrodes 112 .

In addition, the touch driving controller 127 determines the frequency of the driving signal by avoiding the frequency band of the noise component. That is, when a noise component is introduced during a touch sensing operation, the driving unit sets the frequency of the driving signal by excluding the frequency band of the corresponding noise component.

The touch sensing controller 128 converts the information on the frequency of the driving signal to the analog-to-digital converter 450 so that the analog-to-digital converter 450 converts the analog-to-digital to a frequency faster than the frequency of the driving signal. provided to

The touch sensing controller 320 may further include one or more memory devices (not shown) for storing the measured size and associated parameters, and a microprocessor (not shown) for performing necessary calculation and control functions.

The touch sensing controller 320 and/or other parts of the touch sensing device 300 may include one or more application-specific integrated circuits (ASICs), ASSPs, to perform one or more of the functions described herein. (application-specific standard product), etc. may be implemented.

In general, since touch sensing is sensitive to external noise, such as power supply noise, LCD driving noise, R/F noise, and three-wavelength noise, the touch screen is sensed through a filter algorithm or frequency hopping technology to remove separate noise. and operate

However, in the present invention, since the touch is sensed through the change in magnitude of the driving frequency component already known in the sensing signal, it is easy to distinguish between the noise component having a frequency component and the touch component. Therefore, it is easy to solve the noise because it is possible to measure only the change amount of the sensing signal of the desired tracking number using the result of FFT without separate processing for the noise component generated in the operating environment of the touch screen.

On the other hand, since various noise components exist in a mobile phone employing a touch sensing device, the efficiency of touch sensing may be reduced.

12 is a frequency noise spectrum for explaining charger noise generated in a mobile phone employing a touch sensing device.

12, the noise generated by the charger of the mobile phone (that is, the charger noise) is a narrow-band noise component generated at each of about 150 kHz, about 300 kHz, and about 470 kHz, 130 kHz to 180 kHz band, 260 kHz to 370 kHz band, 400 kHz to Includes broadband noise components generated in each of the 560 kHz bands. When such charger noise flows into a touch sensing device employed in a mobile phone, it is difficult to process.

13 is a frequency noise spectrum for explaining the setting of a driving frequency in the frequency noise spectrum of FIG. 12 .

Referring to FIG. 13, avoiding the frequency bands of about 150 kHz, about 300 kHz, about 470 kHz, 130 kHz to 180 kHz, 260 kHz to 370 kHz, and 400 kHz to 560 kHz that are noisy frequency bands in the noise spectrum, respectively, the first driving frequency f0, the second The second driving frequency f1, the third driving frequency f2, and the fourth driving frequency f3 are driven. By measuring only the rate of change of the magnitude of the frequency in the sensed signal, it is possible to avoid noise and perform sensing.

As described above, according to the present invention, since the amount of displacement between adjacent sensing electrodes is amplified, the resolution can be increased.

Although the above has been described with reference to the embodiments, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below you will understand

100, 200, 300: touch sensing device 110: touch panel
112: driving electrode 114: sensing electrode
120, 220, 320: touch sensing controller 122: driving unit
124, 224: sensing unit 126: control unit
127: touch driving control unit 128: touch sensing control unit
410, 510: differential receiver 420, 520: first signal amplifier
430: active filter unit 440: second signal amplification unit
450: analog-digital conversion unit 460: fast Fourier transform unit
470: touch determination unit 480: noise sensing unit

Claims (22)

delete delete delete delete delete delete a driving unit providing a plurality of driving signals having different frequencies to the plurality of driving electrodes; and
A sensing unit for differentially receiving sensing signals sensed through a plurality of sensing electrodes to determine whether a touch occurs,
The sensing unit includes a plurality of current conveyor circuits for differentially receiving the sensing signals to generate a differential sensing signal,
The touch sensing controller, characterized in that the number of the current conveyor circuit is one less than the number of the sensing electrodes. The method of claim 7, wherein the driving unit,
and a digital function generator providing a sine wave to each of the driving electrodes. According to claim 8, further comprising a touch drive control,
The digital function generator is connected to each of the driving electrodes and configured to precisely generate a sine wave with an accurate frequency, period and phase in response to the control of the touch driving controller. ) A touch sensing controller comprising modules. The touch sensing controller according to claim 9, further comprising a noise sensing unit that senses a surrounding noise component and provides a frequency characteristic of the sensed noise component to the touch driving controller. The touch sensing controller of claim 10 , wherein the touch driving controller controls the driving unit to generate the driving signal by avoiding a frequency band of a noise component provided from the noise sensing unit. delete 8. The method of claim 7,
The odd-numbered current conveyor circuit includes a first input terminal connected to the odd-numbered sensing electrode and a second input terminal connected to the even-numbered sensing electrode,
The even-numbered current conveyor circuit comprises a first input terminal connected to the even-numbered sensing electrode and a second input terminal connected to the odd-numbered sensing electrode. The method of claim 13, wherein the sensing unit,
a first signal amplifier including a plurality of signal amplifiers connected to respective output terminals of the current conveyor circuit and first amplifying a sensing signal output from each of the current conveyor circuits;
an active filter unit including a plurality of active filters connected to an output terminal of each of the signal amplifiers and filtering each of the amplified sensing signals;
a second signal amplifier including a plurality of signal amplifiers connected to each of the output terminals of the active filters and second amplifying the active filtered sensing signals;
an analog-to-digital converter including a plurality of analog-to-digital converters and digitally converting each of the second amplified sensing signals;
a fast Fourier transform unit including a plurality of fast Fourier transforms and fast Fourier transforming each of the digitally converted sensing signals; and
The touch sensing controller further comprising a touch determining unit for determining whether a touch occurs based on the amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal. a driving unit providing a plurality of driving signals having different frequencies to the plurality of driving electrodes; and
A sensing unit for differentially receiving sensing signals sensed through a plurality of sensing electrodes to determine whether a touch occurs,
The sensing unit includes a plurality of current conveyor circuits for differentially receiving the sensing signals to generate a differential sensing signal,
A touch sensing controller, characterized in that the number of the current conveyor circuit is the same as the number of the sensing electrodes. 16. The method of claim 15,
The odd-numbered current conveyor circuit is connected to the odd-numbered sensing electrode, and the even-numbered current conveyor circuit is connected to the even-numbered sensing electrode. The method of claim 16, wherein the sensing unit
a first signal amplifier comprising a plurality of signal amplifiers connected to respective output terminals of adjacent current conveyor circuits and first amplifying a sensing signal output from each of the current conveyor circuits;
an active filter unit including a plurality of active filters connected to an output terminal of each of the signal amplifiers and filtering each of the amplified sensing signals;
a second signal amplifier including a plurality of signal amplifiers connected to each of the output terminals of the active filters and second amplifying the active filtered sensing signals;
an analog-to-digital converter including a plurality of analog-to-digital converters and digitally converting each of the second amplified sensing signals;
a fast Fourier transform unit including a plurality of fast Fourier transforms and fast Fourier transforming each of the digitally converted sensing signals; and
The touch sensing controller further comprising a touch determining unit for determining whether a touch occurs based on the amount of change between the frequency magnitudes of the fast Fourier-transformed sensing signal based on the frequency magnitude of the driving signal. 18. The method of claim 17,
The current conveyor circuit connected to the first sensing electrode includes a floating first output terminal and a second output terminal connected to the first signal amplifier,
The current conveyor circuit connected to the last sensing electrode comprises a first output terminal and a floating second output terminal connected to the last signal amplifier. The touch sensing controller of claim 14 or 17, wherein the active filter unit includes any one of a low pass filter and a band pass filter. The touch control system according to claim 14 or 17, wherein the current conveyor circuit, the first signal amplifier, the active filter unit, the second signal amplifier, the analog-to-digital conversion unit, and the fast Fourier transform unit operate. Touch sensing controller, characterized in that it further comprises a sensing controller. The analog-to-digital converter according to claim 14 or 17, wherein the touch sensing control unit converts the information on the frequency of the driving signal to the analog-to-digital converter so that the analog-to-digital converter converts the analog-to-digital signal to a frequency faster than the frequency of the driving signal. Touch sensing controller, characterized in that provided to. a touch panel on which a plurality of driving electrodes and a plurality of sensing electrodes are disposed; and
A touch sensing controller including a driving unit that provides a plurality of driving signals having different frequencies to the driving electrodes, and a sensing unit that differentially receives sensing signals sensed through the sensing electrodes to determine whether a touch occurs but,
The sensing unit includes a plurality of current conveyor circuits for differentially receiving the sensing signals to generate a differential sensing signal,
A touch sensing device, characterized in that the number of the current conveyor circuit is less than or equal to the number of the sensing electrodes by one.

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