KR101627262B1 - Touch cell structure of touch panel - Google Patents

Abstract

The present invention relates to a touch cell structure of a touch panel in which a touch cell is constituted by a new P2G (Pad to Gate) method, which improves the problems of the conventional capacitive touch input device. A conductive pad 50 for forming a capacitance with the touching means when the touching means 25 or the touching means having similar electrical characteristics approaches the predetermined distance d; And a three-terminal type switching device in which a gate terminal is connected to the conductive pad 50 and an output signal is changed corresponding to the potential of the gate terminal due to capacitance between the touch means and the conductive pad 50, And the gate terminal potential of the switching element 40 is determined by the electrostatic capacitance formed in the conductive pad 50. Therefore, the difference in the output signal of the switching element 40 becomes larger as the touch input is made Therefore, it is possible to detect the touch input with a high / low level digital method and to avoid the use of the ADC, so that the structure is simplified, the manufacturing cost is low, and the multi-touch input is recognizable will be.

Description

[0001] The present invention relates to a touch cell structure of a touch panel,

The present invention relates to a touch cell structure of a touch panel, and more particularly, to a touch cell structure having a specialized cell structure, which has a very high detection sensitivity and accuracy for a touch input, can detect a touch input in a digital manner, To a new pad-to-gate type touch cell structure capable of recognizing a touch input.

The touch input device is an input device which is added to a display device such as an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an OLED (Organic Light Emitting Diode), an AMOLED (Active Matrix Organic Light Emitting Diode) And is an apparatus that recognizes an object such as a finger or a touch pen as an input signal when the object touches the screen. Recently, touch input devices have been widely used in mobile devices such as a mobile phone, a PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), and the like. Input-supported desktop computers, Internet Protocol TV (IPTV), state-of-the-art fighters, tanks, and armored vehicles.

Conventionally, various types of touch input apparatuses have been disclosed, but resistive touch input apparatuses having a simple manufacturing process and a low manufacturing cost have been widely used. However, since the resistance type touch panel has low transmittance and pressure must be applied to the substrate, it is inevitable that the durability is inevitably degraded as the use time elapses, and it is difficult to accurately recognize the touch point and the detection by the surrounding environment and noise There is a problem that errors occur frequently.

A capacitive (or 'capacitive') touch input device developed as an alternative to a resistive touch input device detects a touch input in a non-contact manner and has a solution to various problems of a resistive touch input device.

FIG. 1 shows the structure of a conventional capacitive touch panel. 1, a conventional capacitive touch panel has a transparent conductive film formed on the top and bottom surfaces of a transparent substrate 10 made of a film, plastic, glass, or the like, (12) are formed. The transparent conductive film is formed of a transparent metal such as ITO (Indium Tin Oxide) or ATO (Antimony Tin Oxide). The metal electrodes 12 formed at four corners of the transparent conductive film are formed by printing a conductive metal having a low resistivity such as silver (Ag). A resistor network is formed around the metal electrodes 12. The resistance network is formed with a linearization pattern for uniformly transmitting a control signal to the entire surface of the transparent conductive film. A protective film is coated on the transparent conductive film including the metal electrode 12.

The above capacitive touch panel operates as follows. When an AC voltage of a high frequency is applied to the metal electrode 12, it spreads on the front surface of the transparent substrate 10. At this time, when the transparent conductive film on the upper surface of the transparent substrate 10 is lightly touched with the finger 16 (or a conductive material touching means), a certain amount of current is absorbed into the body and the current sensor And calculates the amount of current in each of the four metal electrodes 12 to recognize the touch point.

Such a capacitive touch panel has a long life because it is a soft touch type, has a high light transmittance because only one transparent substrate 10 is used, and has a merit of being coated with a special metal coating on the contact surface. In particular, since the width of a non-active area in which a touch input can not be detected at a panel edge portion is small, it is possible to make the mechanism slim when engaged with a display device.

However, the above-mentioned capacitance type touch panel requires a costly detection device as a method of detecting the magnitude of a minute current, and further requires an ADC for converting the detected current into digital, so that the price is inevitably increased. In addition, there is a problem that the reaction time is prolonged due to the time required for converting the analog signal to digital. Among other things, there is a problem that the difference between the detection current when the touch input occurs and the current before the touch input is very small, so that the detection sensitivity is poor and is susceptible to noise. For example, if the magnitude of the current flowing out of one of the metal electrodes 12 when the touch input is not generated is 1 uA and the magnitude of the current flowing out of the same metal electrode 12 when the touch input occurs is 2 uA, The detection of the difference between the signals by circuit means will cause a decrease in accuracy and a signal recognition error due to noise.

The present invention has been proposed in order to solve a problem that a signal variation due to a touch input is insignificant in a conventional capacitive touch input device and a complicated configuration is required to detect it, With this specialized circuit configuration, it is possible to increase the difference of the detection signal according to the touch input, thereby increasing the detection sensitivity and accuracy of the touch input, detecting the touch input digitally, and using expensive components such as ADC It is an object of the present invention to provide a novel touch cell structure capable of greatly reducing a reaction time, eliminating a false sense due to noise, and recognizing a multi-touch input.

In order to achieve the above object, a touch cell structure according to the present invention is a touch cell structure constituting a unit touch cell (60) of a touch panel, wherein a finger 25 of the body or a touch means having similar electrical characteristics A conductive pad (50) forming an electrostatic capacitance with the touch means when approaching at a predetermined distance (d); And a three-terminal type switching device in which a gate terminal is connected to the conductive pad 50 and an output signal is changed corresponding to the potential of the gate terminal due to capacitance between the touch means and the conductive pad 50, (40).

According to a preferred embodiment, the switching element 40 is connected to an output terminal of the conductive pad 50 and is turned on / off according to a control signal applied to the gate terminal to switch the charging signal to the conductive pad 50 A first switching element 42 of a three-terminal type; And a second switching element 44 to which a gate terminal is connected to the conductive pad 50 and whose output signal changes corresponding to the potential of the gate terminal.

In an embodiment, a capacitor 54 is further provided between the conductive pad 50 and the ground.

The switching device 40 may be a relay, a metal oxide semiconductor (MOS) switch, a bipolar junction transistor (BJT), a field effect transistor (MOSFET), a metal oxide semiconductor field effect transistor (Insulated Gate Bipolar Transistor), and a TFT (Thin Film Transistor).

According to a preferred embodiment, the switching element 40 is a thin film transistor (TFT).

The touch cell structure according to the present invention is constituted by a conductive pad which forms a capacitance between a finger of a user or a touch means having similar conductive characteristics and a three terminal type switching element to which a gate terminal is connected to the conductive pad The gate terminal potential of the switching element is determined by the electrostatic capacitance Ct formed between the touching means and the conductive pad, The output signal of the switching element can be varied by a factor of tens to tens of thousands depending on whether the input signal is high or low and thus the detection sensitivity and detection accuracy for the touch input are very high and the touch input can be detected at high / Unlike the conventional touch panel structure that used ADC, it can detect touch input digitally and has very fast response to signals An active matrix (AM) scheme in which each touch cell actively operates without occurrence of a malfunction or a false sense of signal due to almost no influence of noise, enables independent operation of each touch cell, It is possible to recognize a multi-touch input which is touched at the same time, to have a specialized cell structure, to be able to miniaturize a cell interval, to support touch input for various applications, and to promote development of applications using touch input .

1 is a perspective view showing an example of a conventional capacitive touch panel.
2 is an exploded perspective view showing the structure of a touch panel according to the present invention.
3 is a diagram conceptually illustrating a method of detecting a touch input in the present invention
4 is a view showing a basic structure of a touch cell structure according to the present invention.
Figure 5 is a block diagram conceptually illustrating an embodiment of a memory means.
6 is a block diagram showing a preferred embodiment according to the present invention.
FIG. 7 is a plan view showing a structure of a unit touch cell in the embodiment of FIG.
8 is a cross-sectional view showing a cross-sectional structure taken along a line I-II in Fig. 7
Fig. 9 is a waveform diagram illustrating an example of detecting touch input in the embodiment of Fig. 6
Fig. 10 is a block diagram showing still another embodiment of the present invention
Fig. 11 is a diagram showing a modified embodiment of Fig. 10
12 is a cross-sectional view showing an example in which a capacitor is built in a TFT
Fig. 13 is a diagram showing a touch cell configuration in which a capacitor is incorporated in a TFT
14 is a waveform diagram illustrating a kickback waveform according to whether touch input is performed
15 is a graph showing characteristics of an output current versus gate voltage of a TFT
16 is a diagram showing an example in which a touch input is detected using a comparator
FIG. 17 is a waveform diagram illustrating a waveform upon detection using a comparator
18 is a circuit diagram illustrating the configuration of a sensing cell
19 is a circuit diagram showing another example of the sensing cell

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

First, the present invention relates to a touch cell structure of a touch panel which is additionally provided on a display device such as an LCD, a PDP, an OLED, and an AMOLED or is built in a display device. The touch cell structure according to the present invention is a cell type touch input device in which a plurality of touch cells are arranged in a matrix by dividing an active area capable of real touch input on a touch panel, .

The structure of each unit touch cell is constituted by a conductive pad which forms a capacitance between a finger or a touch means having similar conductive characteristics and a three-terminal type switching element in which a gate terminal is connected to the conductive pad. Here, since the special touch cell structure according to the present invention determines the gate terminal potential of the switching element by the capacitance of the conductive pad, it is referred to as a P2G (Pad to Gate) method, or the capacitance generated by the finger changes the gate terminal potential So that it will be referred to as F2G (Finger to Gate) method. It will be appreciated that the P2G or F2G touch cell structure according to the present invention is distinguished from the conventional capacitive touch panel by this naming scheme.

The switching element is configured as a three-terminal type having a gate terminal capable of controlling turn-on / off. The three-terminal type switching device is used for sensing a signal output from each touch cell, and in another embodiment, additional switching devices for switching a charging signal applied to each touch cell may be further required. For example, a three-terminal type switching element is an element for controlling conduction of an input / output terminal in accordance with a signal applied to a control terminal, and may be a relay, a metal oxide semiconductor (MOS) switch, a bipolar junction transistor (BJT) Transistors, Metal Oxide Semiconductor Field Effect Transistors (MOSFETs), Insulated Gate Bipolar Transistors (IGBTs), and Thin Film Transistors (TFTs). Relay is a device in which the voltage or current applied to the input terminal is output without loss when a current is applied to the control terminal. The BJT is a device in which a voltage higher than the threshold voltage of the base is applied to the base , A certain amount of amplified current flows from the collector to the emitter. The TFT is a switching element used in a pixel portion constituting a display device such as an LCD or an AMOLED, and is composed of a gate terminal serving as a control terminal, a drain terminal serving as an input terminal, and a source terminal serving as an output terminal When a voltage which is higher than the threshold voltage by a voltage applied to the source terminal is applied to the gate terminal, a current that depends on the magnitude of the voltage applied to the gate terminal as it is conducted flows from the input terminal to the output terminal.

Hereinafter, an example in which a TFT is used as a switching element will be described, and the same reference numerals will be given to the switching element and the TFT. The switching of the signals in each touch cell using TFTs is similar to a method in which pixels are formed using TFTs for screen display in a similar LCD (or Active Matrix LCD) or AMOLED. That is, the touch cells 50 referred to in the present invention detect a touch input by an active matrix method. The technical advantage is that the mass production and reliability of the touch panel is good and the counterflow of the signal is prevented, thereby preventing the misunderstanding of the touch input and simultaneously recognizing the multi-touch input in which a plurality of points are touched.

In the following drawings, thicknesses and regions are enlarged to clearly show layers and regions. And, when a part of a layer, an area, a substrate, or the like is referred to as being "on" or "on" another part, it includes not only the case where it is "directly on" another part but also the case where there is another part in the middle. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

2 is an exploded perspective view showing the structure of a touch panel according to the present invention. As shown in the figure, a touch panel of a single substrate 30 is provided on the upper surface of the display device 20. The substrate 30 is made of a light-transmitting material such as glass or film. As shown in the figure, at the edge of the substrate 30, a drive IC 71 for applying a position detection signal, a gate signal and the like to signal lines to be described later is mounted. Although the illustrated embodiment shows an example in which the drive IC 71 is installed as a single IC, the drive IC 71 may be configured separately for outputting and receiving, and the gate IC may be separately configured.

The drive IC 71 is mounted on the edge of the substrate 30 in the form of a chip on film (COF) or a chip on glass (COG). In addition, the drive IC 71 may be formed of an amorphous silicon gate (ASG) in order to reduce the wiring area at the edge of the substrate 30. ASG is a system on glass (SOG) technology that implements the gate IC function on an amorphous silicon glass substrate. ASG can implement the gate IC function directly on the glass substrate and the installation area of the gate IC can be minimized. Further, the drive IC 71 may transmit a signal from the outside of the substrate 30 using an FPC (Flexible Printed Circuit).

Meanwhile, since the touch panel having the touch cell structure of the present invention is composed of a single substrate 30, it can be manufactured very slimly. 2, the touch panel may not be installed on the display device 20 but may be built in the display device 20. In spite of such a design, The light-fast shortening of the " This is one of the important technical advantages of the present invention. For example, in the case of an LCD, a touch panel and a polarizing plate, each composed of the single substrate 30 of the present invention, are stacked on a liquid crystal panel having a TFT substrate and a color filter substrate bonded together, The panel may be embedded in the display device 20. [ As another example, the substrate 30 may be provided on the same substrate as the color filter substrate. For example, the touch cells described later may be formed on the upper surface or the lower surface of the color filter substrate.

Before explaining a specific embodiment of the present invention, the principle of detecting a noncontact touch input in the present invention will be briefly described with reference to Fig. 3, when the finger 25 (or similar conductive touch means) approaches the conductive pad 50, the conductive pad 50 and the finger 25 are spaced apart by a distance of "d" A ". Then, a capacitance "C" is formed between the finger 25 and the conductive pad 50 as shown in the right equivalent circuit and the expression in Fig. When a voltage or current signal is supplied to the conductive pad 50 having the capacitance "C" to accumulate the charges having the magnitude of the charge quantity "Q ", a voltage relation of V = Q / C is formed. At this time, the body is grounded virtually against the earth.

If a predetermined signal is applied to the conductive pad 50 in a state where the finger 25 is opposed to the conductive pad 50 at an interval of d, the electrostatic capacitance C formed between the conductive pad 50 and the finger 25 Is charged. At this time, since the gate terminal of the switching element 40 (preferably a TFT) is connected to the conductive pad 50 as shown in the figure, the time when the electric charge is charged in the conductive pad 50 and the signal accumulated in the electrostatic capacitance C The TFT 40 is turned on for an arbitrary time to be discharged. The magnitude of the discharged signal gradually decreases with time, and when the discharge is performed to some extent, the TFT 40 is turned off.

The present invention detects the non-contact touch input by using the fact that the gate terminal potential of the TFT 40 fluctuates due to the electrostatic capacity between the touch means and the conductive pad 50 in this manner. Since the output signal with respect to the potential at the gate terminal of the TFT 40 is represented by a graph of the logarithm function as described later, the output of the TFT 40 varies depending on the touch input, do. The present invention is clearly distinguished from the conventionally known capacitive touch input device and touch cell structure as the P2G method in which the potential of the conductive pad 50 determines the gate terminal potential of the TFT 40 as described above.

FIG. 4 is a view showing a basic structure of a touch cell structure according to the present invention. FIG. 4 illustrates a touch panel having a 3 * 3 resolution touch cell 60 of the present invention. In order to facilitate the understanding of the present invention, the touch panel 60 will be arranged at a higher resolution, but in the following embodiments, a touch panel having a 3 * 3 touch cell 60 will be described.

Referring to FIG. 4, a plurality of first signal lines 32, second signal lines 34, and auxiliary signal lines 37 are disposed on one surface of a substrate 30. The first signal line 32 is a signal line for applying a position detection signal (or a charging signal) to each touch cell 60 and the second signal line 34 is a signal line for applying a position detection signal And the auxiliary signal line 37 is a signal line for applying an auxiliary signal for observation to each touch cell 60. In the illustrated embodiment, the first signal line 32 and the second signal line 34 are wired in parallel, and the auxiliary signal line 37 is wired in a crossing manner. However, And each signal line may be wired in parallel or wired at different wiring angles. In addition, the signal lines may be wired in an oblique line or in a zigzag form.

4, each unit touch cell is composed of a conductive pad 50 and a three-terminal type switching element 40 to which a gate terminal is connected to the conductive pad 50. In the embodiment shown in FIG. The three-terminal type switching element 40 may be the above-described various switching elements, but is preferably a TFT 40. [ TFT is a device that has already been proven in AMLCD (Active Matrix LCD) or AMLCD.

As shown in the figure, the conductive pad 50 is connected to the first signal line 32 and receives the charging signal from the first signal line 32. [ The gate terminal of the TFT 40 is connected to the conductive pad 50. The drain terminal which is the input terminal is connected to the auxiliary signal line 37 and the source terminal which is the output terminal is connected to the second signal line 34.

The conductive pad 50 is formed of ITO, carbon nanotube (CNT), antimony tin oxide (ATO), indium zinc oxide (IZO), or a transparent body having similar conductive properties. The conductive pad 50 forms an electrostatic capacitance against the finger 25 of the body, and the area of the conductive pad 50 serves as an important factor for determining the electrostatic capacity generated upon touch input. For example, as the area of the conductive pad 50 is increased in the touch cell 60, the capacitance generated upon touch input will become larger.

4 shows the system configuration of the touch panel. As shown in the figure, a touch position detecting unit 70 is provided at one edge or outside of the panel. The touch position detecting section 70 is constituted by a drive IC 71, a timing control section 72, a signal processing section 73 and a memory section 74. Then, the detection signal acquired by the touch position detecting unit 70 is transmitted to the CPU 75. The CPU 75 may be the CPU of the display device 20, the main CPU of the computer device, or the CPU of the touch input device itself. Although not shown, the system configuration further includes a power supply for generating a low or low voltage of signals for touch input detection.

The signal processing unit 73 applies a charge signal to each of the first signal lines 32 via the drive IC 71 and supplies a charge signal to each of the auxiliary signal lines 37 And acquires the coordinate value of the touch cell 60 in which the touch input is generated by detecting a signal received by the second signal line 34. [

The memory means 74 is means for temporarily storing the obtained coordinate values. Although the illustrated embodiment illustrates a case where the touch cell 60 has a resolution of 3 * 3, since it has a higher resolution in practice, a signal may be lost in the course of processing a large number of signals. For example, when the signal processing unit 73 is in the "Busy" state, the position detection signal may not be recognized and the signal may be missed. The memory means 74 prevents loss of such signals.

5 is a block diagram conceptually illustrating an embodiment of a memory means. Referring to FIG. 5, the memory means 74 has an absolute address corresponding to the coordinate value of the touch cell 60. To this end, the memory means 74 has more bits than the number of touch cells 60. 4, when the touch input is generated in the touch cell 60 at the lower rightmost position, the signal processing unit 73 acquires the touch input signal at the "m9" address of the memory means 74 as indicated by a dotted line in FIG. And stores the coordinate values. After one scan of all signals, the memory means 74 is read to determine if there is a missing signal. If the signal corresponding to the coordinate value of m9 is missing and is stored in m9 of the memory means 74, the signal is generated as a normal input signal and the memory means 74 is erased before the next scanning.

FIG. 6 is a plan view showing a preferred embodiment of the present invention. FIG. 6 shows an example in which two switching elements 42 and 44 are formed in the touch cell 60. The embodiment of Fig. 6 is an example in which processing of a signal is easier and stable and multi-touch input is recognized.

As shown in FIG. 6, a plurality of gate signal lines 36 are further arranged on one surface of the substrate 30. The basic circuit configuration in which each touch cell 60 is composed of the conductive pad 50 and the switching element 44 to which the gate terminal is connected to the conductive pad 50 is the same as the embodiment of Fig. A switching element 42 for switching the charging signal to the conductive pad 50 is further provided. The latter switching element 42 is the first switching element 42 and the former switching element 44 is the second switching element 44. [ Preferably, both switching elements 42 and 44 are TFTs.

6, an input terminal is connected to the first signal line 32, an output terminal is connected to the conductive pad 50, and a gate terminal is connected to the gate signal line 36 in the first TFT 42. The gate terminal of the second TFT 44 is connected to the conductive pad 50. The input terminal and the output terminal of the second TFT 44 are connected to the auxiliary signal line 37 and the second signal line 34, respectively.

In the embodiment of FIG. 6, the touch position detector 70 sequentially applies the scan pulses to the respective gate signal lines 36 to turn on the first TFTs 42 in sequence. Alternatively, the gate signal Gn may be turned on at the same time to charge the capacitance between the finger 25 and the conductive pad 50, and then the auxiliary signal line 37 may be sequentially applied to verify the touch position.

FIG. 7 is a plan view showing the structure of a unit touch cell in the embodiment of FIG. 6, and FIG. 8 is a cross-sectional view taken along the line I-II in FIG. ) Will be described in more detail as follows.

Referring to FIG. 7, the first TFT 42 and the second TFT 44 are connected to the conductive pad 50 and the signal lines as in the circuit diagram of FIG. The signal lines are, for example, aluminum-based metals such as aluminum and aluminum alloys, silver-based metals such as silver and silver alloys, copper-based metals such as copper and copper alloys, molybdenum-based metals such as molybdenum and molybdenum alloys, , Tantalum, or the like. The first signal line 32, the second signal line 34, the gate signal line 36 and the auxiliary signal line 37 are formed of two films having different physical properties, that is, a lower film (not shown) (Not shown). The upper film is made of a metal having a low resistivity such as aluminum (Al) or an aluminum alloy such as an aluminum alloy so as to reduce signal delay or voltage drop. Alternatively, the lower film may be made of a material having excellent contact properties with respect to ITO (Indium Tio Oxide) and IZO (Indium Zinc Oxide), such as molybdenum (Mo), molybdenum alloy, and chrome (Cr).

The signal lines are preferably formed entirely of transparency to avoid being seen by the observer. Although not shown, a metal-based signal line may be partially used for insulation between signal lines at the intersections of the signal lines and for reducing the resistance of the signal lines when the signal lines are made of the entire transparency. Further, although not shown, the signal line can be protected by an insulating film. (For example, a gate line and a source line of an LCD) for displaying a screen of a display device or a BM (a gate line and a source line) formed between pixels to conceal a signal line, It is possible to prevent the moire phenomenon due to optical interference with the black matrix. The signal lines formed on the different types of layers are connected to the other components by the contact holes 59.

8, a gate insulating film 43 made of silicon nitride (SiNx) or the like is formed on the gate electrode 56 of the first TFT 42 and the second TFT 44. An active layer 46 overlapping the gate electrode 56 and forming a channel between the drain electrode 57 and the source electrode 58 is formed on the gate insulating film 43. In addition, the active layer 46 is formed so as to overlap with the drain electrode 57 and the source electrode 58 as well. The active layer 46 is formed of hydrogenated amorphous silicon or polycrystalline silicon. On the active layer 46, an ohmic contact layer 47 made of a material such as silicide or n + hydrogenated amorphous silicon in which n-type impurity is highly doped is formed. The ohmic contact layer 47 is a layer for ohmic contact between the drain electrode 57 and the source electrode 58. A protective film 45 is formed on the drain electrode 57 and the source electrode 58 and a conductive pad 50 formed of a transparent conductive material such as ITO is formed on the protective film 45.

A contact hole 59 is used to connect the conductive pad 50 to the source electrode 58 of the first TFT 42 and the gate electrode 56 of the second TFT 44 as shown. The contact hole 59 may be formed in various shapes such as a polygonal shape or a circular shape.

Although not shown, a light blocking layer for blocking light may be formed on the TFTs 42 and 44. The light blocking layer may be formed of a material used for manufacturing the drain electrode 57 and the source electrode 58 of the TFTs 42 and 44 or a material used for manufacturing the gate electrode 56 and an impermeable inorganic material may be used have. The light blocking layer prevents the TFTs 42 and 44 from malfunctioning in response to light.

9 is a waveform diagram showing an example of detecting a touch input in the embodiment of FIG. Referring to this, the touch position detector 70 sequentially provides scan pulses to the respective gate signal lines 36. The gate signal Gn provided by the touch position detection unit 70 has a voltage level enough to allow the gate of the first TFT 42 to enter the active region. For example, it is preferable that the gate signal Gn is set to be 3 V or more larger than the position detection signal Dn transmitted through the first signal line 32. In a preferred embodiment, the Hi voltage level of Dn is 13V and the Hi voltage level of Gn is 18V. Further, in order to stably turn off the first TFT 42, the gate OFF voltage is set to -5 to -7V.

The gate signal Gn has a sufficient observation time between the respective signals. This is to allow a hypothetical capacitor formed by the finger 25 of the body and the conductive pad 50 to have a sufficient charge time by the approach of the body. As shown, between G1 and G2 there is a pause of sufficient observation time 1. The position detection signal Dn applied through the first signal line 32 is provided to keep Hi whenever any Gn is Hi, and preferably also has some rest period when Gn has a rest period.

The touch position detection unit 70 provides the observation voltage through the auxiliary signal line 37. The signal Auxn applied through the auxiliary signal line 37 must be at a Hi level in a certain section of the observation time and may be always provided at a Hi level in all observation time intervals. The auxiliary signal Auxn provides an observation voltage of 3V or more lower than 13V, which is the voltage charged between the finger 25 and the conductive pad 50 by Dn at the Hi level. For example, the observed voltage of Auxn is about 5V.

Referring to FIG. 9, a waveform obtained through the second signal line 34 and a process for acquiring a touch signal through the waveform will be described.

If the body is not accessed even after the gate signal is applied and the subsequent observation time has passed, as in the case where the gate signals G1 and G2 are applied, the signal Sn obtained through the second signal line 34 is as shown And has a waveform. This is because capacitance is not formed in the conductive pad 50 because the body is not accessed. More specifically, when the gate signal G1 is applied, the first TFT 42 is turned on. At this time, since the voltage of Dn is applied to the gate terminal of the second TFT 44, the second TFT 44 is also turned on. However, since the wiring resistance and the parasitic capacitance of the second signal line 44 exist, the signals S1 and S2 obtained as shown in the figure have a curve in a section where the signal is raised to the Hi level and a section in which the signal is falling to the Low level. As shown in the figure, since the gate voltage of the second TFT 44 abruptly drops immediately after the first TFT 42 is turned off and the observation time is changed to G1, Let the time be "T1". However, in this waveform diagram, the time delay generated in the output signal Sn compared to the input signal Dn is ignored.

If the finger 25 is approached to the lower right touch cell 60 at any point in FIG. 6, a capacitance 25 between the conductive pad 50 and the body finger 25 in the touch cell 60 Will be formed. As shown in the waveform diagram of FIG. 9, if a touch occurs in a section where G3 is at a Hi level, a virtual capacitor is formed at the moment when the finger 25 comes close. At this time, in the waveform diagram of FIG. 9, the waveform of S3 may distort the waveform at the time of occurrence of the touch, so that the charging voltage may fluctuate at the beginning of charging. However, soon after charging is completed, S3 rises to Hi level.

When the G3 signal is changed to the observation time, that is, when G3 is turned off, the voltage charged in the imaginary capacitor is discharged, and the gate-side voltage of the second TFT 44 is gradually lowered. ) Shows the inherent output characteristic as shown in S3 waveform. At this time, the time taken for the waveform of Sn to decrease to 50% or less is defined as "T2 ".

Referring to the waveform diagram of FIG. 9, it can be seen that T1 and T2 show considerable time differences. The touch position detecting unit 70 reads the time taken for the waveform of the signal Sn received via the second signal line 34 to fall or the falling voltage (or current) at a predetermined time after the Gn is turned off as described above, Can be obtained.

The embodiment of FIG. 9 is an embodiment for acquiring a touch, and it is possible to acquire a detonation point by another method. For example, all the gate signals Gn are simultaneously turned on to induce charge in a virtual capacitor formed between the body and the conductive pad 50, and then a signal is sequentially applied to the auxiliary signal line 37 to observe the output waveform Method. It will be apparent to those skilled in the art that various ways of acquiring touch signals may be used in accordance with the teachings of the present invention.

10 and 11 illustrate another embodiment of the present invention in which an additional capacitor 54 is added between the conductive pad 50 and the ground in each touch cell 60. FIG. The added capacitor 54 will charge share with the imaginary capacitor formed by the finger 25 of the body, thereby lowering the potential of the gate of the second TFT 44 or making the charging time longer. Accordingly, if the finger 25 is detected, the touch signal can be obtained more stably for approaching the finger 25.

10, in addition to the embodiment of FIG. 6, a capacitor 54 is further connected between the conductive pad 50 and the auxiliary signal line 37. FIG. The touch position detector 70 may sequentially apply a scan pulse to each gate signal line 36 or apply the same gate signal to all the gate signal lines 36. In this case,

In this embodiment, the gate signal Gn and the auxiliary signal Auxn for observation do not necessarily have to be interlocked and can be independently applied. However, since too much time has elapsed after the capacitor 54 is charged by Gn, free discharge may occur in the capacitor 54, and the auxiliary signal Auxn may not be observed because the capacitor 54 is charged by Gn It is preferable to be applied immediately thereafter.

In one embodiment, the ON voltage of Gn is set to 15V. Dn is also applied when Gn is applied and charges the capacitor 54 connected to the gate terminal of the second TFT 44. [ Since the Hi level potential of Dn is a voltage for turning on the second TFT 44, about 10 V is appropriate considering the relationship with Gn. Dn is provided for a sufficient time to charge the capacitor 54. [

Since the voltage of the gate of the second TFT 44 is larger than the voltage of the input terminal Auxn by 3 V or more, the second TFT 44 is always turned on. If the finger 25 is accessed in the lower right touch cell 60 at the time when the auxiliary signal Auxn for observation is applied, the charge stored in the capacitor 54 is discharged to the virtual capacitor formed by the body , Which continues until the potentials of the two capacitors become equal. If the capacitance of the capacitor 54 is sufficiently smaller than the imaginary capacitor formed by the finger 25, the voltage applied to the gate of the second TFT 44 in relation to the magnitude of the auxiliary voltage Auxn , A time point at which the second TFT 44 is not turned on or the magnitude of the output signal Sn is lowered occurs and the touch signal is acquired. The touch signal obtained also in this example is the coordinate value corresponding to "D3, S3".

Referring to FIG. 11, the auxiliary signal line 37 is divided into a first auxiliary signal line 37a and a second auxiliary signal line 37b. One end of the capacitor 54 is connected to the first auxiliary signal line 37a and the input terminal of the second TFT 44 is connected to the second auxiliary signal line 37b.

The present embodiment is different from the embodiment of FIG. 10 only in that an auxiliary signal for observation and an auxiliary signal for status monitoring are separated. The auxiliary signal Aux1-n is applied to the first auxiliary signal line 37a for observation and the auxiliary signal Aux2-n is applied to the second auxiliary signal line 37b for monitoring.

In this embodiment, the ON voltage of Gn is set to 18V. The Hi level potential of Dn is a voltage for turning on the second TFT 44, and is about 12V. As an embodiment, the auxiliary signals Aux1-n for observation can have a potential of -18V at the Low level and 0V at the Hi level. For example, when the auxiliary signal Aux1-n is at the Low level and the capacitor 54 is charged, the potential of the gate of the second TFT 44 drops down to -6 V, so that the second auxiliary signal line 37b The 2FTFT 44 is not conducted. In addition, since the Hi level potential of Dn is 12V at the Hi level (i.e., zero volt) of Aux1-n, stable conduction of the second TFT 44 to the auxiliary signal Aux2-n smaller than about 3V is assured. It is preferable that the auxiliary signal Aux2-n is synchronized with the signal of Aux1-n, and the potential at the Hi level and the potential at the Low level of Aux2-n are also matched with Aux1-n.

10 and 11 can vary the capacitance of the capacitor 54 to control the voltage applied to the gate of the second TFT 44 after charge sharing, Is a factor determining the waveform descent slope of the waveform. In other words, by adding the capacitor 54, the width of the voltage level selection of each signal is widened and the falling slope of the Sn signal is made gentler so that the touch signal can be stably obtained.

The above-described embodiments show touch cell structures according to the present invention. The touch cell 60 is basically configured in the P2G scheme, and several components may be added to this basic configuration. In addition to the embodiments enumerated above, each touch cell 60 may further include additional switching elements, capacitors, resistors, or other electrical components.

The technical feature of the P2G touch cell 60 is that the kick back at the gate terminal of the switching device 40 is largely changed depending on whether the touch input is performed or not, Accordingly, the output signal of the switching element 40 has a difference of several tens to tens of thousands of times, so that the detection sensitivity and accuracy are very high and the touch input can be detected by a digital method.

Hereinafter, an example in which the touch cell structure according to the present invention detects a touch input using a kickback will be described. C1 and C2, which will be described below, represent a capacitor name and a size simultaneously. For example, "C1 " means a capacitor having the name C1 and a capacitance C1.

12 is a cross-sectional view showing an example in which a capacitor is built in a TFT. Referring to this, in the process of manufacturing the TFT, the capacitors Cgd and Cgs are formed between the gate terminal and the drain terminal of the TFT and between the gate terminal and the source terminal. A capacitor Cgd is formed in a region where the drain electrode 57 overlaps with the gate electrode 56 and a capacitor Cgs is formed in a region where the source electrode 58 overlaps with the gate electrode 56. [ The sizes of the capacitors Cgd and Cgs are determined according to the width or length of the TFT. For example, Cgd and Cgs are designed to be about 10 fF (femtoF) to 300 fF depending on the width or length of the TFT.

13 is a view showing a touch cell structure in which a capacitor is embedded in a TFT. In the touch cell structure according to the embodiment of FIG. 6, a state in which a built-in capacitor is added to each of the first TFT 42 and the second TFT 44 . As shown in the figure, a virtual capacitor "Ct" is formed between the finger 25 of the body and the conductive pad 50 at the time of touch input. The signal output through the output terminal of the first TFT 42 is stored in Ct for a predetermined time, and the signal stored in Ct is discharged through a discharge path formed by peripheral elements connected to Ct.

In the circuit configuration for determining the gate terminal potential of the second TFT 44 in accordance with the charge / discharge operation of Ct, the built-in capacitors C1, C2, and C3 of the respective TFTs act as shown in the figure. Here, C1, C2, and C3 are about 10 fF to 300 fF as mentioned above, and Ct can be freely designed by adjusting the distance between the touching means and the conductive pad 50, the facing area, and the like. For example, by selecting the area of the conductive pad 50 to be large, Ct is also designed largely based on the relational expression of FIG. Conversely, the area of the conductive pad 50 is selected to be small (for example, by selecting 1 mm ² or less), and Ct is designed to be small. Preferably, Ct is selected to be 2 to several hundred times larger than C1 to C3, and may be designed to be, for example, several tens of femto F to several tens of pF.

FIG. 14 is a waveform diagram illustrating a kickback waveform according to whether or not touch input is performed, and shows a waveform of a signal in the touch cell structure of FIG. Referring to FIG. 14, the difference in kickback according to whether or not touch input is performed will be described below.

When the on-voltage applied to the gate terminal of the first TFT 42 is "VH" and the off-voltage is "VL", the voltage difference due to on / off becomes a value obtained by subtracting VL from VH. When a voltage having the magnitude of "V1" is applied to the input terminal In1 of the first TFT 42 and VH is applied to the gate terminal Cont1 to turn on the first TFT 42, The voltage measured at the output terminal Out1 of the first TFT 42 is "V2" as in the waveform of "Out1-A ". Here, the transient response characteristics due to the wiring of the signal line and the parasitic resistance are ignored. The voltage measured at the output terminal Out1 of the first TFT 42 is lowered by applying "VL" to the gate terminal Cont1 of the first TFT 42 after a predetermined time to turn off the first TFT 42 . At this time, since C1, C2, and C3 are connected as in the circuit diagram of Fig. 13, the kickback voltage "KB1" at the time when touch input is not generated in the waveform of Out1-A is defined by Equation 1 below.

----- 수식1

----- Equation 1

For example, if VH is 10V, VL is -5V, V1 is 8V, and C1 is equal in magnitude to the sum of C2 and C3, the kickback voltage KB1 is 7.5V. That is, in the waveform of Out1-A, V2 becomes low from 8V to 0.5V. This voltage drop also means that the potential at the conductive pad 50 is lowered from 8V to 0.5V.

On the other hand, in the waveform indicated by "Out1-B" in FIG. 14, the waveform of the voltage measured at the output terminal Out1 of the first TFT 42 when the finger 25 approaches the conductive pad 50 It is a waveform. In this case, since the electrostatic capacity Ct is formed between the finger 25 and the conductive pad 50, the kickback voltage "KB2" at the time of touch input generation in the waveform of Out1-B is expressed by the following equation Is defined as " (2) "

----- 수식2

----- Equation 2

If Ct has a magnitude of three times C1, the kickback voltage KB2 is 3V. That is, in the waveform of Out1-B, V2 becomes low from 8V to 5V.

Out2-A and Out2-B in the embodiment of FIG. 14 exemplify the magnitudes (current values in this example) of signals output from the output terminal Out2 of the second switching device 44, -B. ≪ / RTI >

As we have seen, we can choose the size of Ct by adjusting the spacing and facing area of the touching means and the conductive pad 50. As the Ct is designed to be larger than C1, the denominator value of KB2 And the difference between KB1 and KB2 can be greatly increased.

FIG. 15 is a graph showing characteristics of an output current versus gate voltage of a TFT. Referring to FIG. 15, it can be seen that an output signal has a logarithmic function in contrast to a signal applied to a gate terminal of the TFT. Referring to FIG. 15, it can be seen that Ids of about 1uA flows when the control voltage Vgs applied to the gate terminal of the TFT is 15V, whereas Ids flows 100pA when Vgs is 0V. That is, when the control voltage drops from 15V to 0V, the output current has a difference of about ten thousand times.

That is, the magnification of C 1, C 2, C 3, and Ct corresponding to C 1, C 2, and C 3 can be suitably selected to appropriately design the difference between KB 1 and KB 2, and accordingly, the output signal of the second TFT 44 The difference can be tens or hundreds of thousands of times. Therefore, the touch input detection is easy, and detection accuracy and reliability are very high, and the touch input can be detected by a digital detection method for detecting the high / low level of the signal. In addition, the width and width of the touch cell 60 can be made very small due to the technical advantages.

Meanwhile, in the above-described embodiment, the TFT is referred to as the switching element 40, and the built-in capacitor exists due to the structure in which the gate metal and the source metal are stacked as shown in FIG. 12. However, In which no built-in capacitor is present), a kickback effect can be obtained by adding a capacitor to the switching element 40 as in the circuit diagram of FIG. In addition, although the voltage-driven TFT has been described in the above-described embodiments, the driving method and the detection method may be changed when the switching element is replaced with another switching element. For example, a switching element such as a BJT or an IGBT operates in a current driving type, and a current of several tens of times or more is outputted compared with a current applied to the control terminal. Therefore, switching devices such as BJTs and IGBTs can obtain output current characteristics that show a difference of several tens of times or more as compared with a small difference control current, if a kickback difference is given depending on the touch input.

17 is a waveform diagram illustrating a waveform at the time of detection using a comparator, in which the high / low level of the output signal of the second TFT 44 is converted into a digital signal by a digital method. FIG. 16 is a diagram showing an example of detecting a touch input using a comparator. And recognizes the touch input.

The signal Sn output from the second TFT 44 is input to a comparator as shown in FIG. 16 and is compared with a reference signal. As described above, since the output signal difference of the second TFT 44 is large depending on the presence or absence of the touch input, the signal detection in the comparator is very easy. The output of the comparator is a digital signal having a low or low level and can be read by the touch position detector 70 without any signal conversion.

17, when the touch input is generated and the output signal Sn of the second TFT 44 becomes high in the t1 section, Sn becomes larger than the reference signal and the output of the comparator becomes low or low depending on the circuit configuration . In the t2 period when the touch input is interrupted or the signal disappears after a predetermined time, Sn falls to low, Sn becomes smaller than the reference signal, and the output of the comparator becomes low or high depending on the circuit configuration. Therefore, the touch position detector 70 can digitally process the output of the comparator. Here, although the difference between the high and low of Sn seems to be small in the illustrated example, as mentioned above, this difference is several tens times to tens of thousands times.

When a touch input is detected using a comparator as in the examples of Figs. 16 and 17, a reference signal is used. The reference signal may be formed by configuring a separate reference signal generator in the touch position detector 70.

However, given a constant reference signal may cause a read error in the touch input. For example, suppose that the characteristics of the first TFT 42 change due to factors such as temperature and aging, and a voltage fluctuation of about 2 V occurs in Vgs for generating the same output current. Referring to the graph of FIG. 15, the difference of the output current Ids in a section where Vgs changes from 0 (zero) to 2V is 100 times. If the touch input is detected as a difference between when Vgs is 0 V and when Vgs is 15 V, the difference of Ids is ten times. Therefore, the reference signal is divided into a value between the output signals of the second TFT 44 That is, a current value having a difference of one hundred times). That is, the reference signal can be set by the current value at Vgs 2V. Here, the "interim value" does not always mean an intermediate value. For example, a current value having a difference of ten times or a current value having a difference of a thousand times may be a reference signal.

If the output voltage of the first TFT 42 fluctuates by 2 V, the output of the second TFT 44 approaches the reference signal even though the touch input is not generated. At this time, although the touch input is not generated due to disturbance or the like, the touch input may be detected, which may cause a malfunction.

In the present invention, the sensing cell 61 is used to prevent a malfunction due to the setting of the reference signal. The sensing cell 61 is provided on the panel and has a structure similar to the touch cell 60 for touch input detection. As described above, the sensing cell 61 having a similar structure to the touch cell 60 has the same temperature condition and aged change as the touch cell 60. [ For example, if the TFT of the touch cell 60 has a voltage fluctuation of 2V due to a change in temperature or aging, the sensing cell 61 also generates a reference signal of the same voltage fluctuation. Thus, read errors due to factors such as temperature and aging can be reduced.

18 and 19 show an example of the sensing cell 61. Fig. As in the embodiment of Figs. 4 and 6, the touch input detection is obtained through the output signal of the TFT 40 or the second TFT 44. Fig. Corresponding to the case where an output signal is obtained via one TFT as described above, the sensing cell 61 in the embodiment of Fig. 18 can be constituted by one sensing switching element 64. [ In this example as well, the sensing switching element 64 is a TFT, hereinafter referred to as a sensing TFT 64 and given the same reference numerals.

A separate TFT may be added to the TFT 40 or the rear end of the second TFT 44 in some cases. In this case, the sensing cell 61 is connected to the first sensing TFT 66 and the second TFT 44, 2 sensing TFTs 68 may be connected in sequence. In the illustrated example, the mounting position of the sensing cell 61 is not specified, but the sensing cell 61 may be installed in a non-active area on the panel.

The sensing TFT 64 constituting the sensing cell 61 has the same circuit configuration as that of the TFT 40 or the second TFT 44 at the rear end of the conductive pad 50 of the touch cell 60. [ The drain terminal of the sensing TFT 64 is connected to the auxiliary signal line 36, and the source terminal is connected to the second signal line 34. However, a conductive pad is not connected to the gate terminal of the sensing TFT 64, and a separate gate signal can be applied to the gate terminal. As another example, a TFT having the same circuit configuration as that of the first TFT 42 may be further added to the gate terminal.

The touch position detection unit 70 applies a predetermined control signal to the gate terminal of the sensing TFT 64. [ This control signal is applied to the control terminal of the second TFT 44 of the touch cell 60 and the signal applied to the control terminal of the second TFT 44 of the touch cell 60 when the touch input is generated Quot; signal ". For example, in the above example, 2V will be applied to the control terminal of the sensing TFT 64. If 2V is applied to the gate terminal of the sensing TFT 64, the output of the sensing TFT 64 will correspond to the Ids value when Vgs is 2V. If the voltage of the TFT of the touch cell 60 fluctuates due to the temperature or the aging, the voltage of the sensing TFT 64 also fluctuates under the same condition. Therefore, the reference signal outputted from the sensing TFT 64 also fluctuates do. Therefore, it is possible to prevent the malfunction due to the temperature condition or the aging change as described above, and to stably detect the touch input.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined by the appended claims. Will be apparent to those of ordinary skill in the art.

20: display device 25: finger
30: substrate 32: first signal line
34: second signal line 36: gate signal line
37: Auxiliary signal line 37a: First auxiliary signal line
37b: second auxiliary signal line 40: switching element
42: first switching element 44: second switching element
45: protective film 46: active layer
47: ohmic contact layer 50: conductive pad
54: capacitor 56: gate electrode
57: drain electrode 58: source electrode
59: contact hole 60: touch cell
61: sensing cell 64: sensing switching element
66: first sensing switching element 68: second sensing switching element
70: touch position detection unit 71: drive IC
72: timing control section 73: signal processing section
74: memory means 75: CPU

Claims (27)

1. A touch panel comprising a plurality of touch cells arranged in a matrix,
A touch position detecting unit for sequentially or simultaneously applying a charging signal to each of the touch cells;
A plurality of first elements arranged in each of the touch cells and outputting different output waveforms depending on whether the touching means is approaching or not; And
And a plurality of conductive pads connected to a gate terminal of the first element to generate a capacitor by approaching the touching means,
Wherein the first device outputs a first output waveform according to the charging of the capacitor by the charging signal when the capacitor is generated and the first device is directly conducted by the charging signal when the capacitor is not generated, Outputting an output waveform,
Wherein the first output waveform and the second output waveform are proportional to a difference between an ON voltage of the first element and an OFF voltage of the first element, A smaller voltage drop occurs compared to the waveform, so that the voltage drop width is smaller or the output current value is larger. The method according to claim 1,
Wherein touching is performed by the touch position detecting unit by comparing the first output waveform and the second output waveform. delete The method according to claim 1,
Wherein the touch cell is disposed in an active area of the touch panel. The method according to claim 1,
And a plurality of signal lines configured to apply the charge signal to the touch cell and to connect the touch position detection unit and the touch cell to receive the first output waveform and the second output waveform. The method according to claim 1,
Wherein the touch panel is composed of a single substrate. The method according to claim 1,
Wherein the touch panel is embedded in the display device. The method according to claim 1,
Wherein the touch panel is formed on one of an upper surface and a lower surface of the color filter substrate, The method according to claim 1,
Wherein the touching means comprises an object having a finger or a similar conductive characteristic of the body. The method according to claim 1,
Further comprising a second element configured to control supply of the charge signal to the conductive pad in accordance with a turn-on / turn-off operation. The method according to claim 1,
Wherein the first element is a switching element. The method of claim 10,
And the second element is a switching element. The method according to claim 11 or 12,
Wherein the switching element is a TFT (Thin Film Transistor). The method of claim 5,
Wherein the signal line is formed as a whole of transparency. The method of claim 5,
Characterized in that a part of the signal line is composed of a metal series and is covered with an insulating film. The method of claim 5,
The signal line
A first signal line for applying either the position detection signal or the charging signal to the touch cell;
A second signal line for receiving the first output waveform or the second output waveform from the touch cell; And
And an auxiliary signal line for applying an auxiliary signal for observation to the touch cell. 18. The method of claim 16,
Wherein the first signal line, the second signal line, and the auxiliary signal line are wired in parallel with each other. 18. The method of claim 16,
Wherein the first signal line, the second signal line, and the auxiliary signal line are wired so as to have a predetermined wiring angle mutually. 18. The method of claim 16,
Wherein the first signal line, the second signal line, and the auxiliary signal line are wired in one of an oblique line and a zigzag line. The method according to claim 1,
Wherein a capacitance of the capacitor is proportional to an area size of the conductive pad. The method according to claim 1,
Wherein the touch position detection unit is disposed on one of the edges positioned around the active area of the touch panel or outside the touch panel. 18. The method of claim 16,
The touch position detecting unit
A drive IC for applying a gate signal for controlling the turn-on / turn-off operation of a second element configured to control the supply of the charge signal to the position detection signal or the charge signal or the conductive pad;
Wherein the timing control unit sequentially applies the position detection signal, the charge signal, or the gate signal to the touch cell according to the time division signal, the timing control unit generating a time division signal;
A signal processing unit for obtaining coordinate values of a touch cell in which a touch occurs based on the first output waveform and the second output waveform;
And memory means for storing the coordinate values acquired by the signal processing portion. 23. The method of claim 22,
Wherein the drive IC is mounted on at least one edge portion located around the active region of the touch panel in the form of a chip on film (COF) or a chip on glass (COG). 23. The method of claim 22,
Wherein the drive IC is composed of ASG (Amorphous Silicon Gate) in at least one edge portion located around the active region of the touch panel. 23. The method of claim 22,
The drive IC
A discharge drive IC for applying the position detection signal or the charge signal;
A gate IC for applying the gate signal; And
And a receiving drive IC for receiving the first output waveform and the second output waveform. 23. The method of claim 22,
Wherein the drive IC transmits a signal to the outside of the touch panel using an FPC (Flexible Printed Circuit). 26. The method of claim 25,
Wherein the gate IC is implemented directly on the glass substrate.

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