JP2015075991A - Liquid crystal display device including touch panel function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of input detection by a touch sensor in a liquid crystal display device including a touch panel function.SOLUTION: A display device having a built-in touch panel function includes an active matrix substrate 5, a counter substrate 6, and a liquid crystal layer 7. The active matrix substrate 5 includes an electronic circuit and a wiring line connected to the electronic circuit. The counter substrate 6 faces the active matrix substrate 5. The liquid crystal layer 7 is held between the active matrix substrate 5 and the counter substrate 6. The counter substrate 6 includes, successively from the liquid crystal layer 7 side, a common electrode 12, a color filter layer 11 including a color filter and a lattice-like black matrix, and one electrode 13 of a capacitance type touch panel. The common electrode 12 is a metal electrode formed to overlap the black matrix and is used as the other electrode of the capacitance type touch panel.

Description

  Embodiments described herein relate generally to a liquid crystal display device with a built-in touch panel function.

  For example, electronic devices such as a mobile phone, a personal digital assistant, and a personal computer may be equipped with a display device having a touch panel function as one form of an interface. A display device having a touch panel function has a configuration in which a touch panel substrate is bonded to a display device such as a liquid crystal display device or an organic light emitting diode (OLED) display device.

  As described above, when the external touch panel substrate is mounted on the surface side (outside) of the display panel, the thickness or weight of the entire display device including the display panel increases. Therefore, an in-cell type touch panel in which a touch panel is incorporated inside the display panel has been proposed.

JP 2009-244958 A

  For example, there is an in-cell touch panel built-in liquid crystal display device including a capacitive touch sensor on an active matrix substrate. However, in such a liquid crystal display device, it is necessary to provide a common electrode on a counter substrate disposed to face the active matrix substrate. When a common electrode is provided on the counter substrate, a signal due to capacitive coupling between the finger and the capacitive touch sensor of the active matrix substrate is hardly generated, and the accuracy of input detection by the touch sensor may be reduced.

  On the other hand, it is also possible to form a capacitive touch sensor electrode with a transparent electrode on the counter substrate. However, the sheet resistance of the transparent electrode is, for example, about 100Ω, which is higher than that of the metal electrode, and the time constant becomes large. Therefore, the accuracy of input detection by the touch sensor may be reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal display device with a built-in touch panel function that improves input detection accuracy by a touch sensor.

  A display device with a built-in touch panel function according to one embodiment of the present invention includes an active matrix substrate, a counter substrate, and a liquid crystal layer. The active matrix substrate includes an electronic circuit and wiring connected to the electronic circuit. The counter substrate faces the active matrix substrate. The liquid crystal layer is sandwiched between the active matrix substrate and the counter substrate. The counter substrate includes, in order from the liquid crystal layer side, a common electrode, a color filter layer including a color filter and a grid-like black matrix, and one electrode of a capacitive touch panel. The common electrode is a metal electrode that is formed to overlap the black matrix and is used as the other electrode of the capacitive touch panel.

Sectional drawing which shows an example of the lamination | stacking relationship of the liquid crystal display device concerning this embodiment. The perspective view which shows an example of the transparent electrode and common electrode which were formed in the counter substrate. The side sectional view showing an example of the transparent electrode and common electrode which were formed in the counter substrate. The top view which shows an example of a black matrix. The top view which shows an example of a common electrode. The top view which shows an example of 1 pixel unit of the common electrode with a notch | incision. The top view which shows an example of 1 pixel unit of a black matrix. Sectional drawing which shows an example of the connection state of the terminal of the terminal of the lead-out line from a common electrode, and the wiring or terminal formed in the surface side of the active matrix substrate. The top view which shows an example of a transparent electrode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or substantially the same functions and components are denoted by the same reference numerals, and will be described as necessary.

  FIG. 1 is a cross-sectional view showing an example of a stacking relationship of the liquid crystal display device 1 according to the present embodiment.

  The liquid crystal display device 1 includes an illumination unit 2, a liquid crystal display panel 3, and a protective cover 4. A protective cover 4 is provided on the surface side (upper side or outer side) of the liquid crystal display panel 3. The illumination unit 2 is provided on the back side (lower side or inner side) of the liquid crystal display panel 3. In the present embodiment, the front side is the observer side, and the back side is the inside of the apparatus.

  The illumination unit 2 irradiates light emitted from the back side to the front side of the liquid crystal display panel 3.

  The liquid crystal display panel 3 includes an active matrix substrate 5, a counter substrate 6 disposed so as to face the active matrix substrate 5, and a liquid crystal layer 7 sandwiched between the active matrix substrate 5 and the counter substrate 6. Prepare. The liquid crystal display panel 3 includes a plurality of display pixels arranged in a matrix.

  The active matrix substrate 5 includes a polarizing plate 8 on the back side opposite to the liquid crystal layer 7. The active matrix substrate 5 includes electronic circuits, elements, terminals, and wirings connected to the electronic circuits for realizing the active matrix system.

  The active matrix substrate 5 includes, for example, flexible printed circuits 10 in a frame region on the front surface side. An image display signal and a position detection signal are transmitted and received between the active matrix substrate 5 and the flexible printed circuit board 10. The flexible printed board 10 is formed using, for example, a film substrate.

  The counter substrate 6 includes a common electrode 12, a color filter layer 11, and a transparent electrode 13 in order from the liquid crystal layer 7 side. In the present embodiment, for example, the counter substrate 6 includes a color filter layer 11 on the back surface side (liquid crystal layer side), and further includes a common electrode 12 on the back surface side of the color filter layer 11. The counter substrate 6 includes a touch panel conductive and transparent electrode (Rx electrode) 13 on the front surface side. For example, the color filter layer 11 may be provided on the surface side of the counter substrate 6 and can be changed as appropriate.

  The polarizing plate 9 is formed on the surface side of the transparent electrode 13.

  The protective cover 4 is transparent. For example, a glass plate, an acrylic plate, or polyethylene terephthalate (PET) is used as the protective cover 4. The protective cover 4 may be formed as a transparent dielectric. For example, the protective cover 4 has a thickness of about 1 micrometer to 5 millimeters.

  The transparent electrode 13 is one electrode of a capacitive touch panel.

  The common electrode 12 is the other electrode of the capacitive touch panel.

  The common electrode 12 and the transparent electrode 13 sandwich a dielectric.

  In the present embodiment, the common electrode 12 is a transmission electrode and the transparent electrode 13 is a reception electrode 13. However, the transmission electrode and the reception electrode may be reversed.

  The counter substrate 6 includes a flexible printed circuit board 14 in a frame region on the front surface side, for example. The flexible printed board 14 receives a position detection signal from the wiring of the transparent electrode 13. The flexible printed board 14 is formed using, for example, a film substrate.

  In this embodiment, the common electrode 12 is provided closer to the counter substrate 6 than the conventional liquid crystal display device with a built-in touch panel, and is located near the finger. Therefore, it is possible to improve the detection accuracy of the position information detected by the change in capacitance between the common electrode 12 and the transparent electrode 13.

  Although omitted in FIG. 1, the liquid crystal display device 1, for example, bonds the active matrix substrate 5 and the counter substrate 6 to each other and encloses the liquid crystal layer 7 between the active matrix substrate 5 and the counter substrate 6. It is good also as providing the sealing material for.

  FIG. 2 is a perspective view showing an example of the transparent electrode 13 and the common electrode 12 formed on the counter substrate 5. FIG. 2 is a perspective view of the front side.

  A plurality of transparent electrodes 13 in the first axial direction are formed on the surface side of the counter substrate 5. The plurality of transparent electrodes 13 are parallel.

  On the back surface side of the counter electrode 6, a common electrode 12 in the second axis direction intersecting (for example, orthogonal to) the first axis direction is formed. The plurality of common electrodes 12 are parallel. In FIG. 2, the common electrode 12 on the back surface side is illustrated by a dotted line.

  FIG. 3 is a sectional side view showing an example of the transparent electrode 13 and the common electrode 12 formed on the counter substrate. FIG. 3 shows a vertical cross section parallel to the longitudinal direction of the transparent electrode 13.

  A grid-like black matrix BM is formed on the back side of the counter substrate 6. One frame (one unit) of the lattice corresponds to a subpixel.

  Any of a red filter R, a green filter G, and a blue filter B is formed in the frame of the black matrix BM.

  The common electrode 12 is overlaid on the back side of the black matrix BM. Thus, since the black matrix BM and the common electrode 12 are overlapped, even if the common electrode 12 is made into a metal, the display quality of the observer is not deteriorated. By metallizing the common electrode 12, the common electrode 12 can have a low resistance.

  FIG. 4 is a plan view showing an example of the black matrix BM. FIG. 4 shows a planar pattern on the back side of the counter substrate 6.

  FIG. 5 is a plan view showing an example of the common electrode 12. FIG. 5 shows a planar pattern on the back surface side of the common electrode 12.

  On the back surface side of the counter substrate 6, a black matrix BM having a lattice pattern and a common electrode 12 having a lattice shape but having notches 151 to 154 are overlapped.

  The plurality of cuts 151 to 154 of the common electrode 12 are formed in the second axis direction intersecting with the electrode 13. In the present embodiment, the plurality of cuts 151 to 154 are assumed to be parallel. As described above, the common electrode 12 is divided into the plurality of electrode portions 121 to 125 by the plurality of cuts 151 to 154, thereby enabling position detection based on a change in capacitance. Since each of the plurality of electrode portions 121 to 125 is formed by dividing the common electrode 12, it has a lattice shape smaller than the entire common electrode 12.

  Each electrode part 121-125 is connected with the lead-out lines 161-165. The lead lines 161 to 165 are connected to terminals 171 to 175 on the lower side across the side part of the frame region of the counter substrate 6. The terminals 171 to 175 are made of, for example, ITO (Indium-Tin Oxide).

  The terminals 171 to 175 are electrically connected to the wiring of the active matrix substrate 5 via contacts formed based on metal pearls (conducting particles) such as gold pearls. Thereby, continuity can be ensured between the terminals 171 to 175 and the wiring of the active matrix substrate 5.

  Since the common electrode 12 in FIG. 5 overlaps with the black matrix BM in FIG. 4, the cuts 151 to 154 of the common electrode 12 are not visually recognized by an observer on the front side.

  FIG. 6 is a plan view showing an example of one pixel unit of the common electrode 12 having the notch 151.

  Depending on the width or position of the notch 151, the display quality may deteriorate. However, for example, by forming the cut 151 having a width of about 2 to 6 micrometers, more preferably about 4 micrometers so as to pass through the center of the sub-pixel, it is possible to prevent display quality from being deteriorated.

  FIG. 7 is a plan view showing an example of one pixel unit of the black matrix BM.

  As described above, one frame of the black matrix BM overlaps with one frame of the common electrode 12 and corresponds to a sub pixel.

  FIG. 8 is a cross-sectional view showing an example of a connection state between the terminal 171 at the end of the lead line 161 from the common electrode 12 and the wiring or terminal 18 formed on the surface side of the active matrix substrate 5.

  The terminal 171 of the lead wire 161 from the common electrode 12 and the terminal 18 of the active matrix substrate 5 are electrically connected by conductive particles such as a metal pearl 19, for example. At the time of connection, the metal pearl 19 is crushed, for example, by about 10% in diameter, whereby the contact area is increased and the contact resistance can be stabilized at several tens of Ω.

  In this embodiment, it is not necessary to connect the common electrode 12 to the flexible printed circuit board on the counter substrate 6 side, and the cost is reduced.

  FIG. 9 is a plan view showing an example of the electrode 13.

  The plurality of transparent electrodes 13 are striped transparent electrodes having a major axis in the first axis direction. The plurality of transparent electrodes 13 are parallel. One end of the lead wire 20 is electrically connected to the transparent electrode 13. The other end of the lead wire 20 is electrically connected to the flexible printed circuit board 21 by an anisotropic conductive film or the like.

  In the present embodiment, the liquid crystal display device 1 executes driving based on a display signal and driving based on a position detection signal in a time division manner. The time constant of the transparent electrode 13 affects the detection accuracy and the corresponding size.

  In the present embodiment described above, the common electrode 12 is formed in a lattice shape so as to overlap the black matrix BM. For example, the common electrode 12 can be a metal electrode.

  In the present embodiment, since the transparent electrode 13 is formed at a position close to the finger, the sensitivity as a touch sensor can be increased.

  Therefore, in this embodiment, the resistance value of the common electrode 12 can be lowered without degrading the display quality, and a low-cost, thin, lightweight, and highly sensitive in-cell touch panel function can be realized. it can.

  In the present embodiment, cuts 151 to 154 are formed in the common electrode 12. Thereby, the common electrode 12 can be used as a transmission electrode of a touch panel, the thickness can be reduced, the weight can be reduced, and the cost can be reduced.

  More specifically, in the present embodiment, the common electrode 12 and the transparent electrode 13 sandwich a dielectric, one electrode serves as a receiving electrode of the touch panel, and the other electrode serves as a transmitting electrode of the touch panel. A touch panel can be formed.

  Furthermore, in the present embodiment, since the common electrode 12 overlaps the black matrix BM, even if the common electrode 12 is formed of a metal material, optical characteristics such as transmittance and reflection are not affected. The time constant of 12 can be lowered.

  Furthermore, since the liquid crystal display device 1 according to the present embodiment executes the driving based on the position detection signal and the driving based on the display signal in a time-sharing manner, the time constant of the common electrode 12 is lowered to reduce the cost at high accuracy. A sensor function can be realized.

  This embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Illumination unit, 3 ... Liquid crystal display panel, 4 ... Protective cover, 5 ... Active matrix substrate, 6 ... Opposite substrate, 7 ... Liquid crystal layer, 8, 9 ... Polarizing plate 10, 14, 21 DESCRIPTION OF SYMBOLS ... Flexible printed circuit board, 11 ... Color filter layer, 12 ... Common electrode, 121-125 ... Electrode part, 13 ... Transparent electrode, R ... Red filter, G ... Green filter, B ... Blue filter, BM ... Black matrix, 151- 154 ... notches, 161 to 164, 20 ... lead wires, 171 to 175 ... terminals, 19 ... metal pearls.

Claims (4)

An active matrix substrate comprising an electronic circuit and wiring connected to the electronic circuit;
A counter substrate facing the active matrix substrate;
A liquid crystal layer sandwiched between the active matrix substrate and the counter substrate;
The counter substrate, in order from the liquid crystal layer side, includes a common electrode, a color filter layer including a color filter and a grid-like black matrix, and one electrode of a capacitive touch panel,
The liquid crystal display device with a built-in touch panel function, wherein the common electrode is a metal electrode formed so as to overlap the black matrix and used as the other electrode of the capacitive touch panel. The display device with a built-in touch panel function according to claim 1,
The common electrode is a transmission electrode, and is divided into a plurality of electrode portions by a plurality of cuts,
The liquid crystal display device with a built-in touch panel function, wherein the one electrode is a receiving electrode. The display device with a built-in touch panel function according to claim 1,
The common electrode includes a plurality of electrodes extending in a first direction;
The one electrode includes a plurality of electrodes extending in a second direction intersecting with the first direction, and having a touch panel function built-in liquid crystal display device. The liquid crystal display device with a built-in touch panel function according to any one of claims 1 to 3,
A liquid crystal display device with a built-in touch panel function, wherein driving based on a display signal and driving based on a position detection signal are performed in a time-sharing manner.

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