TOUCH-INPUT DETECTION DEVICE, TOUCH-SCREEN HAVING THE SAME, AND METHOD OF DETECTING A TOUCH-INPUT

A touch-input detection device is disclosed. In one aspect, the device includes a touch panel having first sensing electrodes and second sensing electrodes. The device additionally includes a sensing signal driver configured to generate a sensing signal and to apply the sensing signal to a charge pump unit and the first sensing electrodes. The charge pump unit is configured to generate an output voltage based on the sensing signal and an output signal from the second sensing electrodes. The device further includes a control unit configured to determine whether or not a touch input has been applied on the touch panel based on the output voltage.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

FIG. 1is a block diagram illustrating a touch screen according to some embodiments.

In the illustrated embodiment ofFIG. 1, the touch screen100includes a display device120and a touch-input detection device140. In addition, the touch-input detection device140includes a touch panel160and a touch sensing unit180. Here, the touch sensing unit180may be implemented as a circuit.

The display device120is an output device that outputs (i.e., displays) an image (e.g., text, figure, etc.). For example, an organic light emitting display (OLED) device, a liquid crystal display (LCD) device, a plasma display panel (PDP) device, a cathode ray tube (CRT) device, etc. may be used as the display device120.

The touch-input detection device140is configured to detect touch inputs of users to determine touch-input positions.

The touch panel160is configured to generate an output signal OSGN based on a capacitance change at a capacitive node of the touch panel160(i.e., the capacitance-change occurs due to the touch-input of users) and a sensing signal SSGN output from the touch sensing unit180, and may output the output signal OSGN to the touch sensing unit180.

The touch sensing unit180is configured to determine whether or not the touch-input of users has been made on the touch panel160, and is configured to calculate the touch-input position. The touch sensing unit180is additionally configured to generate the sensing signal SSGN to output the sensing signal SSGN to the touch panel160. In addition, the touch sensing unit180is further configured to receive the output signal OSGN from the touch panel160, determine whether or not the touch-input of users has been made on the touch panel160, and calculate the touch-input position. In example embodiments, the touch sensing unit180determines whether or not the touch-input of users has been made on the touch panel160, and calculates the touch-input position by comparing the sensing signal SSGN with the output signal OSGN.

FIG. 2is a three-dimensional depiction of a touch panel of a touch-input detection device included in a touch screen such as that ofFIG. 1according to one embodiment.FIG. 3is a cross-sectional view of the touch panel ofFIG. 2.

Referring toFIGS. 2 and 3, the touch panel200includes a pair of substrates (i.e., an upper substrate210and a lower substrate220), an electro-rheological fluid260that is placed between the upper substrate210and the lower substrate220, and a plurality of pairs of sensing electrodes250(i.e., a plurality of sensing electrodes230formed on the upper substrate210and a plurality of sensing electrodes240formed on the lower substrate220).

The sensing electrodes230may be formed on the upper substrate210in a first direction. The sensing electrodes240may be formed on the lower substrate220in a second direction. For example, the first direction may be perpendicular to the second direction. In this case, the pairs of the sensing electrodes250may be arranged in a matrix form. That is, a plurality of capacitive nodes may be defined at a plurality of locations corresponding to a plurality of crossing points of the electrodes230formed on the upper substrate210and the electrodes240formed on the lower substrate220.

As a touch-input is made on the upper substrate210, a capacitance of the capacitive node located at a touch-input position may change (e.g., increase). Thus, it is determined that a touch-input of users has been made on the upper substrate210when the capacitance of the capacitive node located at the touch-input position reaches a predetermined threshold value.

Specifically, when a sensing signal SSGN is applied to the sensing electrodes230formed on the upper substrate210, a voltage output from the sensing electrodes240formed on the lower substrate220may change based on the capacitance of the capacitive node. Accordingly, an output signal OSGN may be generated at the sensing electrodes240formed on the lower substrate220, and then the output signal OSGN may be output to the touch sensing unit. Subsequently, the touch sensing unit may calculate the capacitance of the capacitive node by comparing the sensing signal SSGN with the output signal OSGN, and then may determine whether or not a touch-input of users has been made on the touch panel based on the comparison result. However, an operation of the touch-input detection device100is not limited thereto.

FIG. 4is a block diagram illustrating a touch-input detection device according to example embodiments.

Referring toFIG. 4, the touch-input detection device400includes a touch sensing unit410and a touch panel420. The touch sensing unit410includes a sensing signal driver430, a charge pump unit440, and a control unit450. The touch panel420includes first sensing electrodes470and second sensing electrodes480. In example embodiments, the touch sensing unit410further includes an analog-to-digital converter (ADC)460.

The sensing signal driver430is configured to generate a sensing signal SSGN. The sensing signal SSGN may be applied to the charge pump unit440and the first sensing electrodes470of the touch panel420. In example embodiments, the sensing signal SSGN may correspond to a square wave.

When the sensing signal SSGN is applied to the first sensing electrodes470, a voltage output from the second sensing electrodes480may be detected based on a capacitance of a capacitive node. The capacitance corresponds to the capacitive node formed by the first sensing electrodes470and the second sensing electrodes480. Thus, an output signal OSGN may be generated at the second sensing electrodes480by a level of the voltage determined by the capacitance.

The charge pump unit440is configured to receive the sensing signal SSGN from the sensing signal driver430and the output signal OSGN from the second sensing electrodes480of the touch panel420, and is configured to generate an output voltage VO based on the sensing signal SSGN and the output signal OSGN. For example, the charge pump unit may generate the output voltage VO by comparing the sensing signal SSGN with the output signal OSGN. Here, the output voltage VO may depend on the capacitance of the capacitive node that is formed by the first sensing electrodes470and the second sensing electrodes480.

The control unit450is configured to determine whether or not a touch-input of users has been made on the touch panel420based on an output voltage VO. In some example embodiments, the control unit450is configured to determine whether or not a touch-input of users has been made on the touch panel420based on a digitized output voltage DVO, where the digitized output voltage DVO is generated by digitizing the output voltage VO. The control unit450is configured to calculate the capacitance of the capacitive node using the output voltage VO or the digitized output voltage DVO. This is enabled by the fact that the output voltage VO and the digitized output voltage DVO include information related to the capacitance of the capacitive node formed by the first sensing electrodes470and the second sensing electrodes480.

The analog-to-digital converter460is configured to receive the output voltage VO (i.e., an analog signal), and configured to output the digitized output voltage DVO (i.e., a digital signal). In other words, the analog-to-digital converter460is configured to convert the output voltage VO to the digitized output voltage DVO.

FIG. 5is a block diagram illustrating one embodiment a touch input detection device.

Referring toFIG. 5, the touch-input detection device500includes a touch sensing unit510and a touch panel520. The touch sensing unit510includes a sensing signal driver530, a charge pump unit540, and a control unit550. The touch panel520includes first sensing electrodes570and second sensing electrodes580. In example embodiments, the touch sensing unit510may further include an analog-to-digital converter560.

Except for the charge pump unit540, the touch-input detection device500is similar to the touch-input detection device400ofFIG. 4.

The charge pump unit540includes a first current generator541configured to generate a first current i1and a second current generator544configured to generate a second current i2. In example embodiments, the charge pump unit540further includes a capacitor547configured to store charge resulting from the first current i1and the second current i2.

The first current generator541is configured to control the first current i1that is generated based on a sensing signal SSGN output from the sensing signal driver530.

The second current generator544is configured to control the second current i2that is generated based on an output signal OSGN output from second sensing electrodes580of the touch panel520.

The capacitor547is configured to store the charge resulting from the first current i1and the second current i2. The stored charge generates an output voltage VO based on a voltage difference between first and second plates of the capacitor547. In some example embodiments, the capacitor547may correspond to an element caused by parasitic capacitances of the charge pump unit540, electric wiring, etc.

FIG. 6is a block diagram illustrating another embodiment of a touch input detection device.

Referring toFIG. 6, the touch-input detection device600includes a touch sensing unit610and a touch panel620. The touch sensing unit610includes a sensing signal driver630, a charge pump unit640, and a control unit650. The touch panel620includes first sensing electrodes670and second sensing electrodes680. In example embodiments, the touch sensing unit610further includes an analog-to-digital converter660.

Except for the charge pump unit640, the touch-input detection device600is similar to the touch-input detection device500ofFIG. 5.

The charge pump unit640includes a first current generator641configured to generates a first current i1and a second current generator644configured to generate a second current i2. In example embodiments, the charge pump unit640further includes a capacitor647configured to store charge resulting from the first current i1and the second current i2.

The first current generator641is configured to control the first current i1that is generated based on a sensing signal SSGN output from the sensing signal driver630. Specifically, the first current generator641may include a first current source642and a first switch643. The first current source642may generate the first current i1. The first switch643may be controlled by the sensing signal SSGN. The first switch643may turn-on when a voltage level of the sensing signal SSGN is greater than a predetermined voltage level, or when a voltage level of the sensing signal SSGN is smaller than a predetermined voltage level.

The second current generator644is configured to control the second current i2that is generated based on an output signal OSGN output from the second sensing electrodes680of the touch panel620. Specifically, the second current generator644may include a second current source645and a second switch646. The second current source645may generate the second current i2. The second switch646may be controlled by the output signal OSGN. The second switch646may turn-on when a voltage level of the output signal OSGN is greater than a predetermined voltage level, or when a voltage level of the output signal OSGN is smaller than a predetermined voltage level.

The capacitor647is configured to store charge resulting from the first current i1and the second current i2. The stored charge generates an output voltage VO by based on a voltage difference between first and second plates of the capacitor647. In some example embodiments, the capacitor647may correspond to an element caused by parasitic capacitances of the charge pump unit640, electric wiring, etc.

FIG. 7is a block diagram illustrating still another embodiment of a touch input detection device.

Referring toFIG. 7, the touch-input detection device700includes a touch sensing unit710and a touch panel720. The touch sensing unit710includes a sensing signal driver730, a charge pump unit740, a control unit750, and a control signal generator790. The touch panel720includes first sensing electrodes770and second sensing electrodes780. In example embodiments, the touch sensing unit710further includes an analog-to-digital converter760. In addition, the touch sensing unit710may further include a voltage comparator795. In some example embodiments, the control signal generator790may include the voltage comparator795.

Except for the voltage comparator795, the control signal generator790, and the charge pump unit740, the touch-input detection device700is similar to the touch-input detection device500ofFIG. 5.

The voltage comparator795is configured to compare an output voltage VO generated by the charge pump unit740with a predetermined reference voltage VREF, and may output a comparison result signal CRST to the control signal generator790. Specifically, when the output voltage VO is not the same as the predetermined reference voltage VREF as the output voltage VO changes, the voltage comparator795may output the comparison result signal CRST having information that the output voltage VO is not the same as the predetermined reference voltage VREF to the control signal generator790.

The control signal generator790is configured to receive the comparison result signal CRST from the voltage comparator795, analyze the comparison result signal CRST, and generate a control signal CSGN to be output to the second current generator744. Specifically, when the output voltage VO is not the same as the predetermined reference voltage VREF, the control signal generator790may control the second current i2based on the control signal CSGN in order to control charges of the capacitor747. As a result, the output voltage VO may be controlled to be the same as the predetermined reference voltage VREF. In some example embodiments, the control signal generator790is configured to compare the output voltage VO with the predetermined reference voltage VREF, and may generate the control signal CSGN to control the output voltage VO to be the same as the predetermined reference voltage VREF.

The second current generator744included in the charge pump unit740is configured to control the second current i2based on the output signal OSGN output from the second sensing electrodes780of the touch panel720and the control signal CSGN output from the control signal generator790. Thus, the output voltage VO may change because the charges of the capacitor747change as the second current i2changes.

As described above, the touch-input detection device700is configured to control the second current i2to eliminate or reduce parasitic capacitance components of the touch panel720that are generated without any touch-input of users. Therefore, the touch-input detection device700can have an improved operational performance due to an increase of a signal to noise ratio (SNR).

FIG. 8is a block diagram illustrating still another embodiment of a touch input detection device.

Referring toFIG. 8, the touch-input detection device800includes a touch sensing unit810and a touch panel820. The touch sensing unit810includes a sensing signal driver830, a charge pump unit840, a control unit850, and a control signal generator890. The touch panel820includes first sensing electrodes870and second sensing electrodes880. In example embodiments, the touch sensing unit810further includes an analog-to-digital converter860.

Except for the control signal generator890and the charge pump unit840, the touch-input detection device800is similar to the touch-input detection device500ofFIG. 5.

The control signal generator890is configured to receive and analyze a digitized output voltage DVO that is generated by digitizing an output voltage VO output from the charge pump unit840, and generate a control signal CSGN to be output to the second current generator844. Specifically, when the digitized output voltage DVO changes although no touch-input of users exists, the control signal generator890may control the second current i2based on the control signal CSGN in order to control charges of the capacitor847. As a result, the output voltage VO (or, the digitized output voltage DVO) may not be changed.

The second current generator844included in the charge pump unit840is configured to control the second current i2based on the output signal OSGN output from the second sensing electrodes880of the touch panel820and the control signal CSGN output from the control signal generator890. Thus, the output voltage VO may change because the charges of the capacitor847change as the second current i2changes.

As described above, the touch-input detection device800is configured to control the second current i2to eliminate or reduce parasitic capacitance components of the touch panel820that are generated without any touch-input of users. Therefore, the touch-input detection device800may have an improved operational performance due to an increase of an SNR.

FIG. 9is a block diagram illustrating still another example of a touch input detection device ofFIG. 4.

Referring toFIG. 9, the touch-input detection device900includes a touch sensing unit910and a touch panel920. The touch sensing unit910includes a sensing signal driver930, a charge pump unit940, and a control unit950. The touch panel920includes first sensing electrodes970and second sensing electrodes980. In example embodiments, the touch sensing unit910further includes an analog-to-digital converter960. In addition, the touch sensing unit910further includes a voltage comparator995. In some example embodiments, the control unit950includes the voltage comparator995.

Except for the voltage comparator995, the control unit950, and the charge pump unit940, the touch-input detection device900is similar to the touch-input detection device500ofFIG. 5.

The voltage comparator995is configured to compare an output voltage VO generated by the charge pump unit940with a predetermined reference voltage VREF, and may output a comparison result signal CRST to the control unit950. Specifically, when the output voltage VO is not the same as the predetermined reference voltage VREF as the output voltage VO changes, the voltage comparator995may output the comparison result signal CRST having information that the output voltage VO is not the same as the predetermined reference voltage VREF to the control unit950.

The control unit950is configured to receive the comparison result signal CRST from the voltage comparator995, analyze the comparison result signal CRST, and generate a control signal CSGN to be output to the second current generator944. Specifically, when the output voltage VO is not the same as the predetermined reference voltage VREF, the control unit950may control the second current i2based on the control signal CSGN in order to control charges of the capacitor947. As a result, the output voltage VO may be controlled to be the same as the predetermined reference voltage VREF. In some example embodiments, the control unit950may compare the output voltage VO with the predetermined reference voltage VREF, and may generate the control signal CSGN to control the output voltage VO to be the same as the predetermined reference voltage VREF.

The second current generator944included in the charge pump unit940is configured to control the second current i2based on the output signal OSGN output from the second sensing electrodes980of the touch panel920and the control signal CSGN output from the control unit950. Thus, the output voltage VO may change because the charges of the capacitor947change as the second current i2changes.

As described above, the touch-input detection device900may control the second current i2to eliminate or reduce parasitic capacitance components of the touch panel920that are generated without any touch-input of users. Therefore, the touch-input detection device900may have an improved operational performance due to an increase of an SNR.

FIG. 10is a block diagram illustrating another embodiment of a touch input detection device.

Referring toFIG. 10, the touch-input detection device1000includes a touch sensing unit1010and a touch panel1020. The touch sensing unit1010includes a sensing signal driver1030, a charge pump unit1040, and a control unit1050. The touch panel1020includes first sensing electrodes1070and second sensing electrodes1080. In example embodiments, the touch sensing unit1010further includes an analog-to-digital converter1060.

Except for the control unit1050and the charge pump unit1040, the touch-input detection device1000is similar to the touch-input detection device500ofFIG. 5.

The control unit1050is configured to receive and analyze a digitized output voltage DVO that is generated by digitizing an output voltage VO output from the charge pump unit1040, and generate a control signal CSGN to be output to the second current generator1044. Specifically, when the digitized output voltage DVO changes although no touch-input of users exists, the control unit1050may control the second current i2based on the control signal CSGN in order to control charges of the capacitor1047. As a result, the output voltage VO (or, the digitized output voltage DVO) may not be changed.

The second current generator1044included in the charge pump unit1040is configured to control the second current i2based on the output signal OSGN output from the second sensing electrodes1080of the touch panel1020and the control signal CSGN output from the control unit1050. Thus, the output voltage VO may change because the charges of the capacitor1047change as the second current i2changes.

As described above, the touch-input detection device1000may control the second current i2to eliminate or reduce parasitic capacitive components of the touch panel1020that are generated without any touch-input of users. Therefore, the touch-input detection device1000may have an improved operational performance due to an increase of an SNR.

FIG. 11is a flow chart illustrating a method of detecting a touch-input according to example embodiments.

Referring toFIG. 11, the method includes applying S110a sensing signal to first sensing electrodes in a touch panel. Here, the sensing signal may be generated by a sensing signal driver of a touch sensing unit. As the sensing signal is applied to the first sensing electrodes, a voltage level of second sensing electrodes may change based on a capacitance of a capacitive node. Here, the capacitive node may correspond to a pair of sensing electrodes (i.e., a first sensing electrode and a second sensing electrode). That is, the first sensing electrodes and the second sensing electrodes may form a plurality of capacitive nodes in the touch panel. Thus, the method ofFIG. 11includes outputting S120an output signal from the second sensing electrodes to the touch sensing unit.

As described above, the sensing signal controls a first current, and the output signal controls a second current. A capacitor may perform charge and discharge operations using the first current and the second current. Thus, the method ofFIG. 11includes generating S130an output voltage based on the charge and discharge operations of the capacitor using the first current and the second current.

Subsequently, the method ofFIG. 11includes determining S140whether or not a touch input of users has been made on the touch panel based on the output voltage. For example, a control unit may determine whether or not the touch-input of users has been made on the touch panel based on the output voltage. Since the control unit can detect a capacitance change of the touch panel (i.e., the capacitive node) by analyzing the output voltage, the control unit may determine whether or not the touch-input of users has been made on the touch panel by detecting the capacitance-change of the touch panel (i.e., the capacitive node) that is caused by the touch-input of users.

FIG. 12is a block diagram illustrating an electronic device having a touch screen according to example embodiments.

Referring toFIG. 12, the electronic device1200includes a processor1210, a memory device1220, a storage device1230, an input/output (I/O) device1240, a power supply1250, and a touch screen1260. Here, the touch screen1260includes the touch-input detection device100ofFIG. 1. In addition, the electronic device1200may further include a plurality of ports for communicating a video card, a sound card, a memory card, a universal serial bus (USB) device, other electronic devices, etc.

The processor1210may perform various computing functions. The processor1210may be a microprocessor, a central processing unit (CPU), etc. The processor1210may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, the processor1210may be coupled to an extended bus such as a peripheral component interconnection (PCI) bus. The memory device1220may store data for operations of the electronic device1200. For example, the memory device1220may include at least one non-volatile memory device such as an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change random access memory (PRAM) device, a resistance random access memory (RRAM) device, a nano floating gate memory (NFGM) device, a polymer random access memory (PoRAM) device, a magnetic random access memory (MRAM) device, a ferroelectric random access memory (FRAM) device, etc., and/or at least one volatile memory device such as a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a mobile dynamic random access memory (mobile DRAM) device, etc. The storage device1230may be a solid state drive (SSD) device, a hard disk drive (HDD) device, a CD-ROM device, etc. The I/O device1240may be an input device such as a keyboard, a keypad, a touchpad, a mouse, etc., and an output device such as a printer, a speaker, etc. In some example embodiments, the touch screen1260may be included in the I/O device1240. The power supply1250may provide a power for operations of the electronic device1200.

The touch screen1260having touch-input detection device100ofFIG. 1may have an improved operational performance because the touch-input detection device100ofFIG. 1eliminates (i.e., reduces) parasitic components of a touch panel by simply controlling currents generated in a charge pump unit (i.e., with a simple structure). That is, the touch-input detection device100ofFIG. 1may detect a capacitance-change of the touch panel based on a change of an output voltage due to a difference between the currents generated in the charge pump unit.

The present inventive concept may be applied to an electronic device having a touch screen. For example, the present inventive concept may be applied to a television, a computer monitor, a laptop, a digital camera, a cellular phone, a smart phone, a smart pad, a personal digital assistant (PDA), a portable multimedia player (PMP), an MP3 player, a video phone, a game console, a navigation system, etc.