JP2013161129A - Touch screen, touch panel, and display device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch screen having high responsivity and touch coordinate detection accuracy by suppressing effect of parasitic capacitance in a detection circuit and detection wiring.SOLUTION: A display device includes: a touch screen including a transparent substrate, plural column detection wiring lines formed on the transparent substrate and extending in a column direction, and plural row detection wiring lines formed on the transparent substrate and extending in a row direction; and a display module combined and integrated with a rear surface of the touch screen. When the transparent substrate is viewed in a planar manner, an outside edge of a column detection wiring line disposed at the outermost position among the plural column detection wiring lines or an outside edge of a row detection wiring line disposed at the outer most position among the plural row detection wiring lines is disposed inside of an opening inside edge of a conductive grounded front frame that is a component composing the display module.

Description

  The present invention relates to a touch panel and a display device including the same, and more particularly, to a touch panel and a display device with improved responsiveness of touch detection by an indicator such as a finger and detection accuracy of touch coordinates.

  A touch panel that detects a touch by an indicator such as a finger and identifies its position coordinate is attracting attention as one of excellent user interface means, and touch panels using various systems such as a resistive film system or a capacitance system are attracting attention. It has been commercialized.

  Among these methods, as one of the capacitance methods, even when the front side of the touch screen with a built-in touch sensor is covered with a protective plate such as a glass plate having a thickness of several millimeters, the touch of the indicator is not possible. There is a Projected Capacitive Touchscreen method capable of detection. This method has advantages such as the fact that the protective plate can be placed on the front surface, so it is excellent in robustness, can detect touch even when wearing gloves, and has a long life because there is no moving part. ing.

  For example, the configuration of the touch screen in the touch panel described in Patent Document 1 is a parasitic formed on each of a pair of adjacent wirings among a plurality of row detection wirings or column detection wirings extending in the matrix direction of the touch screen. After canceling the capacitance, the capacitance is detected as a differential capacitance, and the coordinates of an indicator such as a finger touched on the touch screen are calculated based on the detection result of the differential capacitance.

  Further, the configuration of the contact detection system (touch panel) described in Patent Document 2 is detected by comparing the capacitance balance between the detection path S including the conductive track (detection wiring) and the reference path R using a differential circuit. With such a configuration, it is possible to remove noise common to the detection path S and the reference path R including relatively close tracks.

JP 2011-138316 A Special table 2011-510375 gazette

  However, due to the deviation (variation) in the parasitic capacitances of adjacent (adjacent) detection lines and switch circuits of the touch screen, even when there is no touch, those differential capacitances appear as detection voltages. In particular, when the detection sensitivity is increased, the detection voltage that appears due to variations in parasitic capacitance cannot be ignored due to the dynamic range of the integration circuit and the A / D conversion circuit.

  Here, the parasitic capacitance of the detection wiring included in the touch screen is mainly influenced by the relationship with the display panel to be combined. Normally, the parasitic capacitance of the detection wiring is, for example, in the case of a liquid crystal display device, when the liquid crystal display panel is a TN (Twisted Nematic) method or a VA (Vertical Alignment) method, The capacitance formed between them is dominant. In the case of the IPS (In Plane Switching) method, the capacitance formed between the shield electrode formed on the surface of the front glass substrate is dominant. Since the parasitic capacitance of the detection wiring formed between the counter electrode and the shield electrode existing on the back side of the touch screen in this way is substantially the same between adjacent detection wirings, The deviation between the adjacent detection wirings of the capacitance becomes small.

  Further, for example, in the case of a liquid crystal display panel, as a form of a liquid crystal display module covered by a so-called shield case, a metal frame having an opening area slightly larger than the display area, together with a backlight and a driving circuit board provided at the rear part. Generally used. The same applies to a display module using another display panel such as an organic EL display panel.

  However, the detection wires at the left and right ends of the plurality of column detection wires and the detection wires at the upper and lower ends of the row detection wires, that is, the outermost detection wires, have a metal frame and an electric field having an opening area slightly larger than the display area. Because of the coupling, if the outermost detection wiring overlaps with the metal frame in a planar manner (overlap) or is not overlapped but is too close, their parasitic capacitance becomes larger than the parasitic capacitance of the adjacent detection wiring, The deviation between the detection wires, that is, the differential capacity increases.

  Further, the metal frame of the display module shields noise from the display panel (mainly electrostatic noise having a drive signal applied to the display panel wiring as a noise source).

  For this reason, in the case of the touch panel (contact detection system) described in the prior art, one of the detection wiring (conducting track) constituting the detection path S and the reference path R in which the capacitance is detected by the differential circuit. When the outermost detection wiring becomes the outermost detection wiring, if the outermost detection wiring overlaps with the metal frame in a planar manner (overlap), or does not overlap but is too close, like the above parasitic capacitance, The noise from the display panel with the other detection wiring forming the set of the path S or the reference path R becomes unbalanced, and the noise removal effect when the detection is performed by the differential circuit is reduced, and the noise removal remaining in the detection result. It appears as a difference.

  In this way, in the case of performing differential detection of capacitance in units of two detection wirings, the detection wirings at the left and right ends of the plurality of column detection wirings and the upper and lower ends of the row detection wirings When the outermost detection wiring is one of the detection wirings, that is, the detection wiring set, the detected differential capacity increases, so that the detection sensitivity cannot be increased and the noise removal effect cannot be sufficiently obtained. was there.

  Moreover, since this tendency becomes more prominent as the touch screen becomes larger, there is a problem in that the touch screen becomes larger.

  The present invention has been made to solve the above-described problems. In the case where the parasitic capacitance is canceled and the outermost detection wiring and the differential capacitance detection are performed or the differential detection is performed, the detection wiring is performed. The detection sensitivity restriction due to the influence of the parasitic capacitance deviation is relaxed, and the reduction of the noise removal effect of differential detection is suppressed, so that detection with high sensitivity and high S / N can be performed, responsiveness and touch coordinates An object of the present invention is to obtain a touch screen, a touch panel and a display device with high detection accuracy.

  A touch screen according to the present invention includes a transparent substrate, a plurality of column detection wirings formed on the transparent substrate and extending in the column direction, and a plurality of row detection wirings formed on the transparent substrate and extending in the row direction. When the transparent substrate is viewed in plan, the outer edge of the column detection wiring arranged on the outermost side among the plurality of column detection wirings, or among the plurality of row detection wirings The outer edge of the outermost row detection wiring is located on the inner side of the opening inner edge of the front frame having the conductivity of the display module that is combined and integrated with the back side of the touch screen. It is characterized by being.

  Since the touch screen according to the present invention is configured as described above, the parasitic capacitance deviation of the detection wiring can be suppressed. As a result, a touch screen with high responsiveness and touch coordinate detection accuracy can be obtained.

It is a top view which shows the structure of the touch screen which the touch panel of Embodiment 1 which concerns on this invention has. It is a perspective view which shows the structure of the touch screen which the touch panel of Embodiment 1 which concerns on this invention has. It is a schematic diagram which shows a structure when the touch screen of Embodiment 1 which concerns on this invention is combined with the display panel. It is a characteristic view for demonstrating the effect of the touch screen of Embodiment 1 which concerns on this invention. It is the figure which showed typically the whole structure of the touchscreen of Embodiment 1 which concerns on this invention. It is a block diagram which shows the structure of the system which performs the touch position detection and calculation operation | movement in the touchscreen of Embodiment 1 which concerns on this invention. It is a schematic diagram which shows the operation timing of the touchscreen of Embodiment 1 which concerns on this invention.

Embodiment 1 FIG.
<Device configuration>
First, the configuration of the touch screen of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view schematically showing a configuration of a touch screen 1 included in the touch panel according to Embodiment 1 of the present invention. FIG. 2 is a perspective view schematically showing a cross section of the touch screen 1.

  Hereinafter, the configuration of the touch screen 1 will be described with reference to the drawings. In the following drawings including drawings in the case of other embodiments, the same reference numerals used in the drawings indicate the same or corresponding components.

  As shown in FIG. 1, the touch screen 1 extends in a column direction (corresponding to the y direction in FIG. 1) on a base substrate (transparent substrate) 12 and is arranged at a predetermined first arrangement interval. A plurality of detection fine column wirings 2 that are repeatedly arranged in a direction (corresponding to the x direction in FIG. 1), extend in the row direction x, and repeat in the column direction y at a predetermined second arrangement interval. A plurality of detection fine row wirings 3 are arranged. A predetermined number of the detection fine column wirings 2 are electrically connected in common by the connection wirings 4 at the upper and lower ends of the detection fine column wirings 2 to constitute a bundle of detection column wiring groups 6. . Similarly, a predetermined number of the detection fine row wirings 3 are electrically connected in common by the connection wiring 5 at the left end and the right end thereof to form a bundle of detection row wiring groups 7. Yes. Note that a bundle of wiring groups in FIG. 1 includes five (predetermined number) detection fine column wirings 2 and detection fine row wirings 3.

  Further, a predetermined number of detection column wiring groups 6 are arranged in parallel in the row direction x. Similarly, a predetermined number of detection row wiring groups 7 are also arranged in parallel in the column direction y. Accordingly, the touch screen 1 is three-dimensionally divided into a predetermined number of areas by a three-dimensional intersection of the predetermined number of detection column wiring groups 6 and the predetermined number of detection row wiring groups 7. When such a configuration is adopted, since the wiring density of the detection fine column wiring and the detection fine row wiring is increased, a touch capacitance value described later can be secured as a large value.

  In FIG. 1, the detection column wiring group 6 and the detection row wiring group 7 (hereinafter, the detection column wiring group 6 and the detection row wiring group 7 are collectively referred to as “detection wiring group” or “detection”. Although illustration of a part of “bundle wiring” may be omitted), as described later, in the present embodiment, the predetermined number of detection wiring groups is set to 8 systems (lines). The detection wiring group is connected to the terminal 10 by lead-out wirings 8 and 9.

  In FIG. 1, when the indicator touches the touch screen 1, the detection fine column wiring 2 and the detection fine row wiring 3 (hereinafter, the detection fine column wiring 2 and the detection fine row constituting the detection wiring group). A touch capacitor is formed between the wiring 3 and the indicator. The number of detection wiring groups and their wiring intervals, the number of fine detection wirings constituting the detection wiring group, the wiring width, and the wiring interval are appropriately selected from the required resolution of the touch position (touch coordinate value) of the touch panel. Is done.

  In the present embodiment, the detection column wiring group and the detection row wiring group may be referred to as a column detection wiring and a row detection wiring, respectively.

  Here, if the detection wiring group is not composed of a plurality of fine detection wirings, but if the detection wiring group is configured as one wide wiring, so-called solid wiring, a large touch capacitance can be secured, but the display panel When the touch panel is disposed on the front surface of the display panel, the wiring group for detection becomes a factor that hinders the transmission of the display light of the display panel, and the transmittance of the display light is lowered. Therefore, in the present embodiment, the detection wiring group is configured by a plurality of fine detection wirings, and the area of the slit-like opening between the fine detection wirings is set large so that the transmittance of the display light is reduced. We are trying to control the decline. However, when accepting the decrease in the transmittance of the display light, a modification in which each detection wiring group is configured as one solid wiring may be applied.

  Next, the configuration of the wiring layer formed on the base substrate 12 constituting the touch screen 1 will be described with reference to FIG. The upper surface layer of the touch screen 1 is a transparent substrate 12 (hereinafter referred to as “base substrate 12”) made of a transparent glass material or a transparent resin. On the back surface of the base substrate 12, ITO (Indium Tin Oxide) or the like is used. The fine row wiring for detection 2 made of the transparent wiring material is formed. Further, a transparent interlayer insulating film 13 such as SiN (silicon nitride) is formed below the detection fine column wiring 2, and a transparent wiring material is formed on the back surface of the interlayer insulating film 13. The detection fine row wiring 3 is formed. Note that the arrangement positions of the detection fine column wirings 2 and the detection fine row wirings 3 are reversed, the detection fine row wirings 3 are formed on the back surface of the base substrate 12, and the back surface of the interlayer insulating film 13 is formed. Alternatively, the detection fine column wiring 2 may be formed.

  The fine detection wiring (detection fine column wiring 2, detection fine row wiring 3) is not made of a transparent wiring using a transparent wiring material such as ITO, but is formed using a metal wiring material such as aluminum. Also good. Even in this case, as described above, the detection wiring group is configured by a plurality of fine detection wirings, and the area of the slit-shaped opening between the fine detection wirings is set to be large. The transmittance | permeability with respect to can be ensured.

  3A is a plan view showing a configuration when the touch screen 1 is combined with the liquid crystal display module 50, and FIG. 3B is a cross-sectional view taken along the line AA. It is a figure which shows the cross section in the case.

  In the present embodiment, as shown in FIG. 3B, on the film forming surface side of the base substrate 12 on which the detection fine column wiring 2 and the detection fine row wiring 3 are formed as described above, For example, the touch screen 1 is configured by adhering a thick glass substrate having a thickness of several mm or a resin substrate such as acrylic through the adhesive layer 17 as the protective substrate 16.

  On the other hand, a liquid crystal display panel 41 and a backlight 49 on its back surface, and a liquid crystal display module 50 covered with a metal front frame 51 and rear frame 52 are disposed on the back surface of the touch screen 1. The front frame 51 and the rear frame 52 are electrically grounded.

  The touch screen 1 is fixed with an adhesive tape 53 on the front surface of the front frame 51, and the touch screen 1 and the liquid crystal display module 50 are integrated.

  At this time, as shown in FIG. 3A, in the touch screen 1, a detection area SA (a broken line SA in the figure) that is an area in which the capacitance is detected by the column detection wiring 6 and the row detection wiring 7. (Region surrounded by). As shown in the figure, it is desirable that the detection area SA is located outside a display area DA (an area surrounded by a broken line DA in the figure) where a display image is further displayed. This is because the peripheral area of the display area is determined from the capacitance formed in the column detection wiring 6 and the row detection wiring 7 when a corresponding area in the display area of the touch screen 1 is touched by an indicator such as a finger. This is because the detection area should be slightly larger than the display area in order to reliably calculate the touch coordinates.

  Further, if the detection area is arranged inside the display area, the boundary of the column detection wiring 6 positioned at the upper end and the lower end and the row detection wiring 7 positioned at the left end and the right end (these four detection wirings will be referred to as the most There is also a possibility that the user may visually recognize the boundary of the external detection wiring.

  Further, the detection area SA is located on the inner side of the opening area FA of the metal front frame 51 of the liquid crystal display module 50 (the area outside the broken line DA in the figure, the hatched area hatched in (a) in the figure). To do. In other words, the outermost detection wiring is configured not to overlap (overlap) with the front frame 51 at least.

  Here, the capacitance difference between the outermost detection wiring and the adjacent detection wiring with respect to the distance d between the inner edge of the opening of the front frame 51 and the outer edge of the outermost detection wiring with respect to the thickness t of the base substrate (glass substrate) 12 is simulated. The results are shown in FIG. In the figure, plots 1 to 4 (numerals 1 to 4 indicated by circles in FIG. 4) indicate cases of glass substrate thicknesses of 0.7 mm, 1.3 mm, 1.9 mm, and 2.8 mm, respectively. The thickness of the adhesive tape 53 was calculated as 0.2 mm. As illustrated, when the front frame 51 and the outermost detection wiring overlap (the distance d between the inner edge of the opening of the front frame 51 and the outer edge of the outermost detection wiring is negative), the distance d increases. That is, as the inner edge of the front frame approaches the outer edge of the outermost detection wiring, the difference in capacitance between the outermost detection wiring and the adjacent detection wiring becomes smaller (asymptotic line a in FIG. Indicated). When the distance d is almost 100%, that is, when the distance between the inner edge of the opening of the front frame 51 and the outer edge of the outermost detection wiring is substantially the thickness of the glass substrate 12, the distance is increased beyond that. However, the capacitance difference between the outermost detection wiring and the adjacent detection wiring does not decrease so much (indicated by an asymptotic line b and a one-dot chain line).

  Therefore, it is desirable to configure the detection wiring pitch and number so that the distance between the inner edge of the opening of the front frame 51 and the outer edge of the outermost detection wiring is larger than the thickness of the glass substrate 12. .

  Further, by disposing a dummy detection wiring that is substantially the same potential as the detection wiring to be detected outside the outermost detection wiring and that does not perform actual detection, the differential capacitance offset can be further reduced. .

  FIG. 5 is a diagram schematically showing the overall configuration of the touch panel according to the present embodiment. A terminal of an FPC (Flexible Printed Circuit) 30 is mounted on a terminal 10 of the touch screen 1 (not shown in FIG. 5, see FIG. 1) by using an ACF (Anisotropic Conductive Film) or the like. The touch screen 1 of FIG. 5 functions as a touch panel by electrically connecting the end of the detection wiring group of the touch screen 1 and the controller board 31 via the FPC 30.

  In addition, a switch circuit (not shown) that sequentially selects two adjacent ones of each of the plurality of column detection wirings 6 and each of the plurality of row detection wirings 7 is mounted on the controller board 31. A detection processing circuit including a differential detection circuit that receives two adjacent column detection wirings 6 or two adjacent row detection wirings 7 selected by the switch circuit and detects a differential capacitance thereof; A detection / coordinate calculation system 100 including a touch coordinate calculation circuit that performs touch coordinate calculation processing on the touch screen 1 of the touch position of the indicator based on the detection result of the differential capacity is mounted, and the calculated instruction The value of the touch coordinates on the touch screen 1 at the touch position of the body is output as detected coordinate data to an external computer (not shown) or the like.

FIG. 6 is a block diagram illustrating a circuit configuration of a detection / coordinate calculation system 100 that detects a touch operation and calculates touch coordinates in the touch panel according to the present embodiment. The detection / coordinate calculation system 100 performs detection processing. A circuit 23, a detection control circuit 24, and a touch coordinate calculation circuit 25 are provided.

In the present embodiment, as an example, the number of column detection wirings 6 and row detection wirings 7 is 8 systems each (in FIG. 4, detection column wiring groups Wx1 to Wx8, detection row wiring groups Wy1 to Wy8). The case will be described. A switch circuit that switches the connection to 2 to 1 is referred to as a 2 to 1 selector circuit.

  As shown in FIG. 6, each of the row detection wirings Wy1 to Wy8 and each of the column detection wirings Wx1 to Wx8 of the touch screen 1 is detected by a detection processing circuit 23 via a terminal 10 (see FIG. 1) and an FPC 30 (see FIG. 5). Is electrically connected.

  The detection processing circuit 23 is provided with a switch circuit 20 connected to the column detection wires Wx1 to Wx8 and a switch circuit 21 connected to the row detection wires Wy1 to Wy8. The switch circuit 20 and the switch circuit 21 each include two pairs. 1 selector circuits Sr1 to Sr8 and 2 to 1 selector circuits Sc1 to Sc8.

  The row detection wirings Wy1 to Wy8 are connected to the selector circuits Sr1 to Sr8 constituting the switch circuit 20, respectively, and are connected to the node a or the node b of the selector circuits Sr1 to Sr8 according to an instruction from the detection control circuit 24. Here, the node a of the selector circuits Sr1, Sr3, Sr5 and Sr7 is connected to the subsequent two-to-one selector circuit S1 through the output node N1 (first output node), and the selector circuits Sr2, Sr4, Sr6 and The node a of Sr8 is connected to the subsequent 2-to-1 selector circuit S2 via the output node N2 (second output node), and all the nodes b of the selector circuits Sr1 to Sr8 are connected to the ground (ground potential). Has been.

  Similarly, the column detection wirings Wx1 to Wx8 are connected to the two-to-one selector circuits Sc1 to Sc8 constituting the switch circuit 21, and are connected to the node a or the node b of the selector circuits Sc1 to Sc8 according to an instruction from the detection control circuit 26. Connected. Here, the node a of the selector circuits Sc1, Sc3, Sc5 and Sc7 is connected to the subsequent two-to-one selector circuit S1 via the output node N1, and the node a of the selector circuits Sc2, Sc4, Sc6 and Sc8 is connected to the output a. It is connected to the subsequent 2-to-1 selector circuit S2 via the node N2, and all the nodes b of the selector circuits Sc1 to Sc8 are connected to the ground.

  Note that all the nodes b of the selector circuits Sr1 to Sr8 and the selector circuits Sc1 to Sc8 may be connected to a predetermined potential other than the ground so as to be compatible with the differential capacitance detection circuit 22 in the subsequent stage.

  The selector circuits S1 and S2 are circuits for connecting the outputs of the row detection wiring and the column detection wiring to the respective nodes a or b in accordance with an instruction from the detection control circuit 24. The selector circuits S1 and S2 The node b of the circuit S2 is connected in common, and the connection node N10 is connected to the differential capacitance detection circuit 22 as an input node (first input node). Similarly, the node b of the selector circuit S2 and the node a of the selector circuit S2 are connected in common, and the connection node N20 is connected to the differential capacitance detection circuit 22 as an input node (second input node). In the differential capacitance detection circuit 22, a difference C10-C20 between the capacitance C10 formed at the input node N10 and the capacitance C20 formed at the input node 20 is detected, and then converted into digital data. Output as a capacity detection result.

  With such a configuration, the differential capacitance formed in the adjacent column detection wiring 6 and the adjacent row detection wiring 7 is detected by the differential capacitance detection circuit 22.

  The selector circuits S1 and S2 are complementarily switched so that when one of the connections to the node A is selected, the other is connected to the node B.

    The output of the differential capacitance detection circuit 22 is connected to the touch coordinate calculation circuit 25. The touch coordinate calculation circuit 25 calculates touch coordinates based on the differential capacitance detection result of the differential capacitance detection circuit 22, Detection coordinate data is output.

<Operation>
<Touch detection operation>
Next, the operation of the detection / coordinate calculation system 100 will be described.
The basic operation of the detection / coordinate calculation system 100 is to connect two adjacent row detection wirings or column detection wirings of the touch screen 1 sequentially to the differential capacitance detection circuit 22 as the operation of the detection processing circuit 23. Thus, the difference between the two capacitances is detected by the differential capacitance detection circuit 22, and the difference capacitance detection result is output to the subsequent touch coordinate calculation circuit 25. The touch coordinate calculation circuit 25 calculates touch coordinates based on the differential capacitance detection result of the differential capacitance detection circuit 22 and outputs detected coordinate data.

  FIG. 7 is a timing chart of the touch capacitance detection operation. As shown in part (a) of FIG. 7, first, detection by the row detection wiring is performed, and the connection of the switch circuit is switched so that the row detection wirings Wy1 and Wy2 are targeted for detection. That is, in accordance with an instruction from the detection control circuit 24, the selector circuits Sr1 and Sr2 connected to the row detection wires Wy1 and Wy2 in the switch circuit 20 are both connected to the node a (see FIG. 6), and the row detection wire Wy1. And Wy2 are connected to selector circuits S1 and S2, respectively. In FIG. 7, periods during which the selector circuits S1 and S2 are connected to the row detection wirings Wy1 and Wy2, respectively, are shown in part (b) and part (c) of FIG.

  On the other hand, the other selector circuits Sr3 to Sr8 of the switch circuit 20 are switched to the node b, and the row detection wirings Wy3 to Wy8 are connected to the ground. Further, the selector circuits Sc1 to Sc8 in the switch circuit 21 connected to the column detection wirings are switched to the node b, and the column detection wirings Wx1 to Wx8 are connected to the ground.

  In this way, both the selector circuits S1 and S2 are switched to the node a in parallel with the row detection wirings Wy1 and Wy2 being connected to the selector circuits S1 and S2, respectively. FIG. 7D shows a period in which the selector circuits S1 and S2 are both switched to the node a and a period in which both are switched to the node b.

  First, during the period when both the selector circuits S1 and S2 are switched to the node a, the row detection wirings Wy1 and Wy2 are connected to the input nodes N10 and N20 of the differential detection circuit 22, respectively. Then, in the differential detection circuit 22, the differential capacitance between the capacitance Cy1 when the row detection wiring Wy1 is connected to the input node N10 and the capacitance Cy2 when the row detection wiring Wy2 is connected to the input node N20 ( Cy1-Cy2) is detected. Then, the detection result is taken into the touch coordinate calculation circuit 25.

  With this simple configuration, it is possible to eliminate the influence of the parasitic capacitance and detect the touch capacitance to the adjacent detection wiring.

  Digital detection data output by the differential detection circuit 22 is captured and held in the touch coordinate calculation circuit 25 at a predetermined timing. In part (g) of FIG. 7, digital detection data capturing timing in the touch coordinate calculation circuit 25 is shown by blocks.

  As described above, the detection processing circuit 23 can detect the touch capacitance Ct by detecting the differential capacitance between the touch capacitance and the parasitic capacitance of the adjacent detection wiring.

  Next, during the period when both the selector circuits S1 and S2 are switched to the node b, the row detection wirings Wy2 and Wy3 are connected to the input nodes N10 and N20 of the differential detection circuit 22, respectively. Then, in the differential detection circuit 22, the differential capacitance between the capacitance Cy2 when the row detection wiring Wy2 is connected to the input node N10 and the capacitance Cy3 when the row detection wiring Wy3 is connected to the input node N20 ( Cy2-Cy3) is detected. Then, the detection result is taken into the touch coordinate calculation circuit 25.

  In this way, the selector circuits Sr1 to Sr8 of the switch circuit 20 are sequentially switched, and in conjunction with this, the selector circuits S1 and S2 are switched, and the connection between the input nodes N10 and N20 of the differential detection circuit 22 and the row detection wiring is sequentially switched. Thus, differential detection of the capacitance of the row detection wirings Wy1 and Wy2, differential detection of the capacitance of the row detection wirings Wy2 and Wy3,... Differential detection of the capacitance of the row detection wirings Wy7 and Wy8, etc. Capacitance differential detection processing proceeds in adjacent row detection wirings.

  After the differential detection of the capacitances of the adjacent row detection wirings is completed, the selector circuits Sc1 to Sc8 of the switch circuit 21 are sequentially switched in the same manner, and the selector circuits S1 and S2 are switched in conjunction with this to detect the differential detection circuit. By sequentially switching the connection between the 22 input nodes N10 and N20 and the column detection wiring, the differential detection of the capacitance between the column detection wirings Wx1 and Wx2, the differential detection of the capacitance between the column detection wirings Wx2 and Wx3,... The differential detection processing of the capacitance of the adjacent column detection wiring proceeds, such as the differential detection of the capacitance of the column detection wirings Wx7 and Wx8.

    Through the above processing, the difference in capacitance formed between adjacent detection wirings is sequentially detected, and the digital detection data is held in the touch coordinate calculation circuit 25. Then, the touch coordinate calculation circuit 25 performs touch determination processing using the digital detection data held for the row detection wirings Wy1 to Wy8 and the column detection wirings Wx1 to Wx8, and when it is determined that there is a touch. Then, the coordinates on the touch screen 1 on which the touch is performed by performing the interpolation process are calculated and output.

  In the touch coordinate calculation circuit 25, for example, the touch determination is performed in the same manner as the touch coordinate calculation process described in Patent Document 1, and when it is determined that there is a touch, the touch coordinates are calculated using interpolation calculation. Although it is output, detailed description is omitted here.

  As described above, the back side of the touch screen 1 is fixed and integrated with the liquid crystal display module 50 to form a liquid crystal display device. Then, the display light of the liquid crystal display panel 40 in the liquid crystal display module 50 is visually recognized by the user as the desired display light corresponding to the image signal passes through the touch screen 1. Further, the touch panel including the touch screen 1 calculates touch coordinates as described above, and outputs the touch coordinates.

  By adopting such a configuration. It is possible to detect a touch capacitance with high sensitivity, and to obtain a display device having a touch panel function with improved calculated touch coordinate accuracy.

  At this time, in the touch screen 1, a reduction in display light transmittance is suppressed by setting a large area of the opening between the fine detection wires in the detection wire group including a plurality of fine detection wires. Therefore, most of the display light from the liquid crystal display panel 40 passes through the touch screen 1. For this reason, even if the touch screen 1 is disposed on the front surface of the liquid crystal display panel 40, the display luminance is hardly lowered.

  Note that a liquid crystal display device can also be configured in the same manner as in the present embodiment using a liquid crystal other than a TN liquid crystal such as an STN (Super Twisted Nematic) liquid crystal.

  In this embodiment, a liquid crystal display device is described as the display device. However, the present invention can also be applied to other types of display devices such as an organic or inorganic EL (Electro Luminescence) display device or PDP (Plasma Display Panel). It is.

  In addition, according to the present embodiment, the touch screen 1 is pasted and integrated with the liquid crystal display panel 41 to constitute the liquid crystal display device, so that it is possible to eliminate the touch screen holding mechanism that has been conventionally required. It is possible to reduce the thickness of the entire apparatus.

  Further, since the display device is configured by integrating the touch screen 1 and the liquid crystal display panel 41, the display to the display caused by foreign matters such as dust mixed in the gap between the touch screen 1 and the liquid crystal display panel 41 is prevented. The influence can be prevented.

In this embodiment, the liquid crystal display module has been described as an example of the display module. However, other display modules such as an organic EL display module may be used.
Moreover, although the frame of the display module has been described as being made of metal, for example, it may be a resin-coated one.
Further, the touch screen 1 is configured to be fixed with the adhesive tape 53 on the front surface of the front frame 51. However, the entire back surface of the touch screen 1 is adhered to the liquid crystal display module 50 with a transparent adhesive sheet, for example, so You may comprise so that the screen 1 and the liquid crystal display module 50 may be integrated.

<Effect>
As described above, in the touch screen according to the first embodiment, each of the outer edges of the two outermost column detection wirings out of the plurality of column detection wirings and the plurality of row detection wirings. Each of the outer edges of the two outermost outermost detection wirings is on the inner side in plan view than the inner edge of the opening of the front frame of the display module that is combined and integrated on the back surface side of the touch screen. With this configuration, the parasitic capacitance deviation of the detection wiring can be suppressed.

  For this reason, it is possible to detect the capacitance formed in a set of adjacent lines of a plurality of column detection wirings or a plurality of row detection wirings by detecting the differential capacitance, thereby canceling the parasitic capacitance. The detection sensitivity restriction due to the influence of the wiring parasitic capacitance deviation can be relaxed, the reduction of the noise removal effect of differential detection can be suppressed, detection can be performed by canceling the parasitic capacitance, and high sensitivity and high S / N. Detection is possible.

  In the touch panel according to the present invention, the parasitic capacitance is canceled by detecting the differential capacitance of the capacitance formed in the adjacent set of wirings of the plurality of column detection wirings or the plurality of row detection wirings of the touch screen. When detection is performed, the detection sensitivity restriction due to the influence of the detection wiring parasitic capacitance deviation can be relaxed, and the reduction of the noise removal effect of differential detection can be suppressed, and detection can be performed by canceling the parasitic capacitance. At the same time, detection with high sensitivity and high S / N becomes possible, and responsiveness and detection accuracy of touch coordinates can be improved.

  Thereby, a touch panel and a display device with high responsiveness and touch coordinate detection accuracy can be obtained.

  DESCRIPTION OF SYMBOLS 1 Touch screen, 2 detection fine column wiring, 3 detection fine row wiring, 4,5 connection wiring, 6 detection column wiring group, 7 detection row wiring group, 12 base board, 16 protection board, 20, 21 Switch circuit, 22 differential detection circuit, 23 detection processing circuit, 24 detection control circuit, 25 touch coordinate calculation circuit, 41 liquid crystal display panel, 50 liquid crystal display module, 51 front frame, S1, S2 selector circuit, FA front frame opening area , SA detection area, DA display area.

Claims (7)

A transparent substrate;
A plurality of column detection wirings formed on the transparent substrate and extending in the column direction;
A plurality of row detection wirings formed on the transparent substrate and extending in a row direction;
A touch screen with
When the transparent substrate is viewed in plan, the outer edge of the column detection wiring arranged on the outermost side among the plurality of column detection wirings, or the row detection wiring arranged on the outermost side among the plurality of row detection wirings The outer edge of
The display module integrated and combined with the back side of the touch screen is electrically conductive and is located inside the opening inner edge of the front frame to be grounded;
Touch screen featuring. When the transparent substrate is viewed in plan,
The outer edge of the column detection wiring arranged on the outermost side among the plurality of column detection wirings, or the outer edge of the row detection wiring arranged on the outermost side among the plurality of row detection wirings,
2. The touch screen according to claim 1, wherein the touch screen is disposed at a distance equal to or greater than a thickness of the transparent substrate and from an inner edge of the opening of the front frame.   Each of the plurality of column detection wirings and the plurality of row detection wirings includes a rectangular column-direction bundle wiring including a plurality of detection column wirings electrically connected in common, and a plurality of electrically connected common wirings. The touch screen according to claim 1, wherein the touch screen is a rectangular row-direction bundle wiring including a plurality of detection row wirings. A transparent substrate;
A plurality of column detection wirings formed on the transparent substrate and extending in the column direction;
A plurality of row detection wirings formed on the transparent substrate and extending in a row direction;
A touch screen with
When the transparent substrate is viewed in plan, the outer edge of the column detection wiring arranged on the outermost side among the plurality of column detection wirings, or the row detection wiring arranged on the outermost side among the plurality of row detection wirings The outer edge of
The display module integrated and combined with the back side of the touch screen is electrically conductive and is located inside the opening inner edge of the front frame to be grounded;
A touch screen featuring:
A first switch circuit for sequentially selecting a set of adjacent ones of the plurality of column detection wirings;
A second switch circuit for sequentially selecting one set adjacent to each other among the plurality of row detection wirings;
A capacitance detection circuit that detects a capacitance formed in a pair of adjacent wirings selected by the first and second switch circuits as a differential capacitance;
A touch coordinate calculation circuit for calculating coordinates of an indicator touching the touch screen based on the detection result of the differential capacitance output from the capacitance detection circuit;
Touch panel equipped with. The first and second switch circuits have first and second output nodes, respectively.
Capacitance detection circuit
First and second input nodes;
First and second selector circuits that supply the first and second input nodes with complementary outputs from the first and second output nodes, respectively,
The touch panel according to claim 4, wherein the first and second selector circuits perform a switching operation in conjunction with a selection operation in the first and second switch circuits. A touch having a transparent substrate, a plurality of column detection wirings formed on the transparent substrate and extending in a column direction, and a plurality of row detection wirings formed on the transparent substrate and extending in a row direction Screen,
A display module combined and integrated on the back side of the touch screen;
With
When the transparent substrate is viewed in plan view,
The outer edge of the column detection wiring arranged on the outermost side among the plurality of column detection wirings, or the outer edge of the row detection wiring arranged on the outermost side among the plurality of row detection wirings,
More than the inner edge of the opening of the front frame that has electrical conductivity and is grounded, which is a component constituting the display module.
Being inside,
A display device.   The display device according to claim 7, wherein the touch screen is adhesively fixed to the front side of the display module.

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