Patent Publication Number: US-2011050647-A1

Title: Touch system and display device comprising the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     An exemplary embodiment relates to a touch system technology, and more particularly, to a touch system capable of performing a reliable sensing operation against external light and a display device comprising the same. 
     2. Description of the Related Art 
     As a known touch sensor, a capacitive type touch sensor is generally used, which detects a user&#39;s touch position by sensing a change in capacitance of the touch sensor, which occurs at a contact portion when a human body having higher permittivity than air touches the touch sensor. 
     In the capacitive touch sensor, the touch sensing operation is sensitively reacting to a shape of an electrode formed on a circuit substrate at a touch position. Therefore, the sensitivity of the touch sensing operation will be various depending on the electrode and a permittivity of a dielectric surrounding the same. 
     In recent years, a touch sensor using an optical sensor module has been developed. The touch sensor of the optical sensor module senses light emitted by the optical sensor module through a light receiving unit. 
     However, the touch sensor of the optical sensor module senses whether or not a user&#39;s touch is made at a position which a user does not actually touch because reflected light by the user&#39;s touch and light incident from the outside are sensed by the light receiving unit. This causes a malfunction of the touch sensor and deteriorates the reliability of the touch sensor. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide a touch system capable of performing a reliable touch sensing operation against external light. 
     Further, the present invention has been made in an effort to provide a display device comprising the touch system capable of performing the reliable touch sensing operation against the external light. 
     An exemplary embodiment of the present invention provides a touch system that comprises: a substrate; an optical sensor module comprising a light emitting unit and a light receiving unit disposed on the bottom of the substrate to be adjacent to each other; and sensing control circuit driving the light emitting unit and sensing whether or not a user&#39;s touch is made on the substrate on the basis of a sensing signal sensed through the light receiving unit. 
     The sensing control circuit comprises a pulse generator outputting a pulse signal of a first frequency band; a filter filtering the sensing signal outputted from the light receiving unit in the first frequency band; and a comparator comparing the pulse signal with a signal filtered by the filter and senses whether or not the user&#39;s touch is made in accordance with a comparison result. 
     Another exemplary embodiment of the present invention provides a touch system that comprises: a backlight unit; a panel unit positioned on the top of the backlight unit and comprising at least one light receiving transistor; and a sensing control circuit driving the backlight unit and sensing whether or not a user&#39;s touch is made on the panel unit on the basis of a sensing signal sensed by at least one light receiving transistor. 
     The sensing control circuit comprises: a pulse generator outputting a pulse signal of a second frequency band; a filter filtering the sensing signal outputted from the light receiving unit in the second frequency band; and a comparator comparing the pulse signal with a signal filtered by the filter and sensing whether or not a user&#39;s touch is made in accordance with a comparison result. 
     Yet another exemplary embodiment of the present invention provides a display device that comprises: a display panel outputting an image; a touch system positioned on the top of the display panel to display the image to a user and sensing whether or not a user&#39;s touch is made output a touch coordinate; and a controller for controlling an operation of the display panel on the basis of the touch coordinate. 
     According to a touch system and a display device comprising the same according to an exemplary embodiment of the present invention, it is possible to filter noise generated by light incident from the outside by controlling an optical sensor module of the touch system to operate in a predetermined frequency band. Accordingly, it is possible to detect a coordinate of a user&#39;s touch position by accurately sensing the user&#39;s touch position and to implement a reliable touch system and a display device comprising the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic block diagram of a touch system according to an exemplary embodiment of the present invention; 
         FIG. 2  is diagram showing a waveform depending on an operation of the touch system of  FIG. 1 ; 
         FIG. 3  is a schematic block diagram of a touch system according to another exemplary embodiment of the present invention; and 
         FIG. 4  is a schematic block diagram of a display device of a touch structure according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The accompanying drawings illustrating exemplary embodiments of the present invention and contents described in the accompanying drawings should be referenced in order to fully appreciate operational advantages of the present invention and objects achieved by the exemplary embodiments of the present invention. 
     Hereinafter, the present invention will be described in detail by describing exemplary embodiments of the present invention with reference to the accompanying drawings. Like elements refer to like reference numerals shown in the drawings. 
       FIG. 1  is a schematic block diagram of a touch system according to an exemplary embodiment of the present invention and  FIG. 2  is diagram showing a waveform depending on an operation of the touch system of  FIG. 1 . 
     Referring to  FIG. 1 , the touch system  100  according to the exemplary embodiment may comprise a substrate  101 , an optical sensor module  110  and a sensing control circuit  120 . 
     The substrate  101  may be made of a transparent material, i.e., an acryl or transparent resin, glass, or the like. The substrate  101  may transmit light outputted from a light emitting unit  111  to be described below, i.e., first light L 1  to the outside 
     (L 1 ′) or transmit light inputted from the outside, i.e., third light L 3  to a light receiving unit  113 . 
     The optical sensor module  110  may be disposed on the bottom of the substrate  101 . The optical sensor module  110  may comprise two sensors disposed adjacent to each other, i.e., the light emitting unit  111  and the light receiving unit  113 . The light emitting unit  111  and the light receiving unit  113  may be a light emitting diode, a photo diode, or a pinned photo diode, but are not limited thereto. 
     The light emitting unit  111  may light or flicker at a predetermined frequency in response to a drive signal TS outputted from the sensing control circuit  120 . For example, the sensing control circuit  120  may output a drive signal TS for controlling the light emitting unit  111  to light or flicker at several to hundreds of KHz in order to prevent the light receiving unit  113  from being influenced by the third light L 3  inputted from the outside. 
     The light receiving unit  113  may output a sensing signal RS by sensing reflected light generated when the first light L 1  outputted from the light emitting unit  111  is reflected by the substrate  101 , i.e., second light L 2  or the third light L 3  inputted from the outside. 
     The sensing control circuit  120  may sense whether or not a user&#39;s touch is made by extracting only a signal in a predetermined frequency band, i.e., a sensing signal RS in the same frequency band as a frequency band of the drive signal TS from the sensing signal RS outputted from the light receiving unit  113 . 
     A light shielding wall  115  may be formed between the light emitting unit  111  and the light receiving unit  113 . The light shielding wall  115  may prevent the light L 1  outputted from the light emitting unit  111  from being directly inputted into the light receiving unit  113  without being reflected through the substrate  101 . The light shielding wall  115  may be made of a material absorbing or fully reflecting light without transmitting the light, According to the exemplary embodiment, the light shielding wall  115  may be formed even between a pair of optical sensor modules adjacent to each other. 
     The sensing control circuit  120  may comprise a light emitting unit control circuit and a light receiving unit control circuit. 
     The light emitting unit control circuit may include a pulse generator  121  and a driver  122 . 
     The pulse generator  121  may generate and output a pulse signal P 1  having a predetermined frequency band, i.e., a first frequency band. The first frequency band may be one frequency band among frequency bands of several to hundreds of KHz and may be changed depending on the exemplary embodiments. 
     The driver  122  may generate and output the drive signal TS from the pulse signal P 1  of the first frequency band. The driver  122  may generate the drive signal TS for operating the light emitting unit  111  by amplifying the pulse signal P 1 . 
     The light receiving unit control circuit may include a converter  123 , a filter  124 , a comparator  125 , and a counter  126 . 
     The converter  123  may convert and output the sensing signal RS outputted from the light receiving unit  113  into a voltage signal VRS. 
     The filter  124  filters a predetermined frequency from the voltage signal VRS converted by the converter  123 , i.e., only the same frequency band as the first frequency band of the driving signal TS to output a filtered signal VRS′. The filter  124  may be a band pass filter, but is not limited thereto. 
     The comparator  125  may output a comparison result CS by comparing the pulse signal P 1  outputted from the pulse generator  121  with the filtered signal VRS′ outputted from the filter  124 . 
     The comparator  125  may output a comparison result CS having a first level, i.e., a low level when the filtered signal VRS′ and the pulse signal P 1  deviate from an error range so as not to be the same as each other. Further, the comparator  125  may output a comparison result CS having a second level, i.e., a high level when the filtered signal VRS′ and the pulse signal P 1  are the same as each other within the error range. 
     The counter  126  may output a touch sensing signal TD in response to the comparison result CS outputted from the comparator  125 . For example, the counter  126  may count the comparison result CS for a predetermined counting time and output the touch sensing signal TD for detecting whether or not the user&#39;s touch is made in accordance with a counting result. At this time, the counter  126  may control user&#39;s touch sensitivity of the touch system  100  by controlling the counting time. 
     Referring to  FIGS. 1 and 2 , for t 0 -t 1  of a time axis T, the pulse generator  121  of the sensing control circuit  120  may output the pulse signal P 1  of the first frequency band. The first frequency band of the pulse signal P 1  is different from the frequency band of the third light L 3  inputted from the outside. 
     The driver  122  may output the drive signal TS based on the pulse signal P 1  and the light emitting unit  111  may output the first light L 1  in response to the drive signal TS. 
     For the time t 0 -t 1  of the time axis T, when the user&#39;s touch is not inputted into the substrate  101 , the first light L 1  outputted from the light emitting unit  111  may be outputted to the outside (L 1 ′) or the second light L 2  reflected by the substrate  101  may be inputted into the light receiving unit  113 . Further, the third light L 3  inputted from the outside may be inputted into the light receiving unit  113 . 
     Herein, the first light L 1  outputted from the light emitting unit  111  may be represented by a sum of the light L 1 ′ outputted from the outside and the second light L 2  inputted into the light receiving unit  113 . Since the user&#39;s touch is not inputted, the second light L 2  may have a size smaller than the light L 1 ′ outputted to the outside. 
     The light receiving unit  113  may output the sensing signal RS sensed by the second light L 2  and the third light L 3  and the converter  123  may convert and output the sensing signal RS into the voltage signal VRS. 
     The filter  124  may filter and output a signal of a predetermined frequency band, that is, a voltage signal VRS of the same frequency band as the first frequency band of the drive signal from the converted voltage signal VRS. At this time, since the signal sensed by the light receiving unit  113  has a frequency band different from the voltage signal VRS by the third light L 3  inputted from the outside, the corresponding signal may be removed by the filter  124 . 
     The comparator  125  may output a comparison result CS by comparing the pulse signal P 1  with the filtered signal VRS′. 
     For example, since the user&#39;s touch is not inputted at the time t 0 -t 1  of the time axis T, the signal VRS′ filtered by the filter  124  may be represented in a smaller size than the pulse signal P 1  and the comparator  125  may output the comparison result CS having the first level. 
     The counter  126  may output a touch sensing signal TD having the first level on the basis of the comparison result CS outputted from the comparator  1 . The sensing control circuit  120  may recognize that a user does not perform the touch input in the touch system  100  on the basis of the touch sensing signal TD having the first level. 
     Meanwhile, for a time t 1 -t 2  of the time axis T, when the user&#39;s touch is inputted into the substrate  101 , the first light L 1  outputted from the light emitting unit  111  may be inputted into the light receiving unit  113  as the second light L 2  by being reflected by the substrate  101  and the user&#39;s touch. Further, the third light L 3  inputted from the outside may be inputted into the light receiving unit  113 . 
     Herein, the first light L 1  outputted from the light emitting unit  111  may be full-reflected by the substrate  101  and the user&#39;s touch and the reflected second light L 2  may be full-reflected in the same manner as the first light L 1  within the error range. 
     The light receiving unit  113  may output the sensing signal RS sensed by the second light L 2  and the third light L 3  and the converter  123  may convert and output the sensing signal RS into the voltage signal VRS. 
     The filter  124  may filter and output the voltage signal VRS at the same frequency band as the first frequency band of the drive signal TS from the converted voltage signal VRS. At this time, the signal which the light receiving unit  113  receives light by the third light L 3  may be removed by the filter  124 . 
     The comparator  125  may output a comparison result CS by comparing the pulse signal P 1  with the filtered signal VRS′. 
     For example, since the user&#39;s touch is inputted for the time t 1 -t 2  of the time axis T, the filtered signal VRS′ may be represented by the same size as the pulse signal P 1  within the error range. In addition, the comparator  125  may output a comparison result CS having the second level. 
     The counter  126  counts the comparison result CS having the second level for the predetermined counting time Δt and may output the touch sensing signal TD having the second level on the basis of the counting result. 
     For example, the counter  126  may count the comparison result CS having the second level for a predetermined counting time Δt of approximately 3 seconds and may output the touch sensing signal TD having the second level on the basis of the counting result. 
     The counting time Δt of the counter  126  may be controlled by those skilled in the art or a user (i.e., an end user) and may control the user&#39;s touch sensitivity of the touch system  100 . 
     The sensing control circuit  120  may recognize that the user perform the touch input in the touch system  100  on the basis of the touch sensing signal TD having the second level. 
       FIG. 3  is a schematic block diagram of a touch system according to another exemplary embodiment of the present. 
     Referring to  FIG. 3 , the touch system  200  according to the exemplary embodiment may comprise a panel assembly  201  and a sensing control circuit  120 . The sensing control circuit  120  of the exemplary embodiment may be the same as the sensing control circuit  120  of the touch system  100  shown in  FIG. 1 . 
     The panel assembly  201  may comprise a panel unit  210 , a backlight unit  220 , and a protection layer  230 . 
     The panel unit  210  may display an image by using light provided from the backlight unit  220 . The panel unit  210  may be a liquid crystal panel charged with liquid crystals therein, but may be a PDP panel or an organic EL panel. 
     The panel unit  210  may comprise a plurality of thin film transistors (TFTs). For example, the panel unit may comprise a drive transistor  211  and a light receiving transistor  213  used as the light receiving unit. The plurality of light receiving transistors  213  may be formed adjacent to the drive transistor  211 . 
     The backlight unit  220  operates by a drive signal TS provided from the sensing control circuit  120  to provide light to the panel unit  210 . The backlight unit  220  may be used as a light emitting unit. The backlight unit  220  may be configured by a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED). 
     The protection layer  230  may protect the panel unit  210  from the outside by covering the whole surface of the panel unit  210 . The protection layer  230  may be made of a transparent material, i.e., an acryl or transparent resin, or the like. 
     The sensing control circuit  120  may comprise the light emitting unit control circuit and the light receiving unit control circuit as described with reference to  FIG. 1 . 
     The light emitting unit control circuit may control operations of the panel assembly  201  and the backlight unit  220 . The light emitting unit control circuit may comprise a pulse generator  121  and a driver  122 . 
     The pulse generator  121  may generate and output a pulse signal P 1  having a predetermined frequency band, i.e., a second frequency band. The second frequency band may be, for example, any one of the frequency bands of several MHz. 
     The driver  122  may generate and output the drive signal TS from the pulse signal P 1  of the second frequency band. The backlight unit  220  may be lighted or flickered in the second frequency band in response to the drive signal TS outputted from the driver  122 . 
     The light receiving unit control circuit may sense the user&#39;s touch input from the sensing signal RS outputted form the light receiving transistor  213  of the panel assembly  201 . The light receiving unit control circuit may comprise a converter  123 , a filter  124 , a comparator  125 , and a counter  126 . Operations of the components are the same as those described with reference to  FIGS. 1 and 2 . 
     That is, the light receiving unit control circuit of the exemplary embodiment may perform the same operation as the operation of the light receiving unit control circuit shown in  FIG. 1  except for receiving the sensing signal RS from the light receiving transistor  213  of the panel assembly  201 . 
       FIG. 4  is a schematic block diagram of a display device of a touch structure according to an exemplary embodiment of the present invention. In the exemplary embodiment, for easy description, the display device of the touch structure comprising the touch system shown in  FIG. 1  will be described. 
     Referring to  FIGS. 1 and 4 , the display device  300  of the touch structure according to the exemplary embodiment may comprise a touch system  100 , a display panel  310 , and a controller  320 . 
     The touch system  100  may comprise an optical sensor module  110  and a sensing control circuit  120 . The touch system  100  may further comprise a coordinate detector  150  capable of outputting a touch position of a user  330  from a touch sensing signal TD outputted from the sensing control circuit  120  depending on a touch input TI of the user  330  as a touch coordinate (X, Y). 
     The touch system  100  may be positioned on the top of the display panel  310 . The touch system  100  may display an image IS provided from the display panel  310  to the user  330  and output the touch coordinate (X, Y) by sensing the touch input from the user. 
     The display panel  310  is positioned on the bottom of the touch system  100  and may provide the image IS to the user  330  through the touch system  100 . The display panel  310  may display panels such as a CRT, an LCD, a PDP, and the like and employ all known display devices. 
     The controller  320  may output at least one command signal CMD for controlling an operation of the display panel  310  on the basis of the touch coordinate (X, Y) provided from the touch system  100 . 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the actual technical protection scope of the present invention must be determined by the spirit of the appended claims.