JP2014098825A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal panel which can prevent lowering of a yield due to lowering of flatness of a resin layer while preventing image display abnormality due to electrostatic charge of a front polarizing plate.SOLUTION: An opposing substrate 13 has a transparent conductive film 33 which constitutes a touch detection function between the transparent conductive film 33 and an array substrate 12 formed thereon. The opposing substrate 13 is arranged so as to be opposed to the array substrate 12 in the state where the transparent conductive film 33 is positioned in an opposite side to the array substrate 12. A liquid crystal layer 14 is sealed between the array substrate 12 and the opposing substrate 13. A front polarizing plate 16 has a low-resistance conductive film 36 formed thereon, and is arranged on the transparent conductive film 33 of the opposing substrate 13. A cover glass 18 has translucency. A resin layer 19 is formed by curing a fluid adhesive 41, and sticks the cover glass 18 and the front polarizing plate 16 each other. The front polarizing plate 16 is provided with a projection 37 which projects from the outer edge and is electrically connected to a ground potential.

Description

  Embodiments described herein relate generally to a liquid crystal display element incorporating a capacitive touch detection function.

  Conventionally, liquid crystal panels with a touch panel used in mobile phones (portable terminals) such as smartphones have various configurations, and generally an external type (out-cell type) in which a touch panel is pasted on the liquid crystal panel. And a built-in type (in-cell type) in which at least a part of the touch panel sensor is built in the liquid crystal panel. Compared to the out-cell type with an external touch panel, the in-cell type built in the liquid crystal panel has the advantage that the device can be made thinner and lighter and the original optical characteristics of the liquid crystal panel can be maintained. On the other hand, the manufacturing process becomes complicated and there are many problems that affect the manufacturing yield.

JP 2012-47801 A JP 2008-209468 A

  In a hybrid in-cell touch panel sensor with a part of the touch panel sensor built in the liquid crystal panel, there is a possibility that an abnormality may occur in the image display due to charging on the polarizing plate on the front side (display side) when the sensor is driven. Therefore, it is necessary to provide an antistatic shield structure. In general, a thin conductive film is applied on the polarizing plate on the front side and a charge is dropped to the ground via a copper foil tape.

  At this time, the flatness of the front side of the liquid crystal panel is lost due to the bonding of the polarizing plate on the front side and the copper foil tape, and in the subsequent cover glass bonding step, the bonded portion of the polarizing plate on the front side and the copper foil tape There is a possibility that problems such as non-uniformity of the spread of the synthetic resin serving as an adhesive, non-uniformity of the pressure-bonding force, and mixed-in bubbles may affect the yield.

  The problem to be solved by the present invention is to provide a liquid crystal display element capable of preventing an image display abnormality due to charging of a polarizing plate and preventing a decrease in yield due to a decrease in flatness of an adhesive layer. .

  The liquid crystal display element of the embodiment is a liquid crystal display element with a built-in electrostatic capacity type touch detection function. The liquid crystal display element includes an array substrate, a counter substrate, a liquid crystal layer, a polarizing plate, a protective plate, and an adhesive layer. The counter substrate includes on its surface a transparent conductive film that constitutes a touch detection function with the array substrate. The counter substrate is disposed to face the array substrate with the transparent conductive film positioned on the side opposite to the array substrate. The liquid crystal layer is sealed between the array substrate and the counter substrate. The polarizing plate has a conductive film on the surface and is disposed on the transparent conductive film of the counter substrate. The protective plate has translucency. The adhesive layer is formed by curing a fluid adhesive and bonds the protective plate and the polarizing plate together. The polarizing plate includes a protruding portion that protrudes from the outer edge and is electrically connected to the ground potential.

It is sectional drawing which shows a part of liquid crystal display element of one Embodiment. It is a top view which shows a part of liquid crystal display element same as the above.

  Hereinafter, the configuration of an embodiment will be described with reference to FIGS. 1 and 2.

  1 and 2, reference numeral 11 denotes a liquid crystal panel as a liquid crystal display element. This liquid crystal panel 11 is an in-cell type that incorporates a capacitive touch detection function used in a portable terminal such as a smartphone. It is a touch panel sensor. In the liquid crystal panel 11, a square array substrate 12 and a square counter substrate 13 are arranged to face each other with a predetermined gap (cell gap) therebetween, and the liquid crystal layer 14 is interposed between the substrates 12 and 13. And, with a spacer (not shown) that holds a gap between the substrates 12 and 13 interposed, the substrates 12 and 13 are pasted by a sealing member (not shown) such as a thermosetting resin or an ultraviolet (UV) curable resin. A back polarizing plate (not shown) which is a flat (not shown) polarizing plate is attached to the array substrate 12 on the side opposite to the counter-facing substrate 13 (anti-liquid crystal layer 14). A liquid crystal layer 14) side is attached with a flat (other) polarizing plate 16 and an active area where a plurality of pixels are arranged in a matrix and an image can be displayed, that is, a display region 17, is square. And is formed in Against polarizing plate 16, a cover glass 18 is bonded through a resin layer 19 as an adhesive layer is a protective plate. In the following description, the display side (upper side in FIG. 1) of the liquid crystal panel 11 is referred to as the front side, and the opposite side (lower side in FIG. 1) is referred to as the back side, that is, the rear side. Further, the liquid crystal panel 11 will be described below as a transmission type that transmits planar light from a backlight (not shown) and displays an image, and is capable of active matrix color display. A reflection type that reflects the incident light, or a semi-transmission type that combines the transmission type and the reflection type may be used, and a monochrome display that does not perform color display or the like can also be used.

  The array substrate 12 includes a flat (one) substrate body 21 which is a transparent and insulating glass substrate. Although not shown, a plurality of image wiring portions (scanning lines and signal lines) for image display are formed in a grid pattern at positions corresponding to the display area 17 on one main surface (front surface) of the substrate body 21. In addition, separately from these image wiring sections, a plurality of detection wiring sections (scanning lines, scanning lines for readout, readout lines, precharge lines) for touch detection are formed in a grid pattern. Furthermore, on one main surface (front surface) of the substrate body 21, there are transparent pixel electrodes that form pixels in the display region 17 at the intersections of the image wiring portions, and switching elements that drive the pixel electrodes, respectively. A thin film transistor (TFT) or the like is formed, and a transparent electrode is formed at the intersection of the detection wiring portion. An alignment film for aligning the liquid crystal material is formed on the substrate body 21 so as to cover the entire pixel electrode and transparent electrode. Further, the array substrate 12 is arranged to face the counter substrate 13 with its three side portions substantially coincided with each other, and the side portion side that does not coincide with the counter substrate 13 serves as a connection region 24 protruding from the counter substrate 13. In addition, a circuit unit (IC) 25 for driving each thin film transistor and detecting a user's touch operation is mounted on the connection region 24, and a flexible printed circuit board (FPC) 26 is electrically connected. ing.

  The flexible printed circuit board 26 electrically connects the circuit section 25 and an external circuit (not shown). For example, the terminal section 28 on one end side is thermocompression bonded via an anisotropic conductive film (ACF). Yes. The other end of the flexible printed circuit board 26 extends outward from the array substrate 12, and is folded back to the rear side of the liquid crystal panel 11 (array substrate 12) to be electrically connected to an external circuit (not shown). It is stored in a housing (not shown).

  The counter substrate 13 includes a flat (other) substrate body 31 that is a transparent and insulating glass substrate. Although not shown, a counter electrode, which is a common electrode, is formed at a position corresponding to the display area 17 on one main surface (rear surface) of the substrate body 31, and a color filter layer is formed at a position corresponding to each pixel. A (colored layer) is formed, and a light shielding layer for preventing light leakage from the backlight is formed. An alignment film for aligning the liquid crystal material is formed on one main surface (rear surface) of the substrate body 31 so as to cover the entire counter electrode and each layer. Further, a transparent conductive film 33 is formed in a square shape on the other main surface (front surface which is the front surface) of the counter substrate 13 so as to cover at least the entire display region 17. In other words, the counter substrate 13 is disposed to face the array substrate 12 with the transparent conductive film 33 as the front side opposite to the array substrate 12. This transparent conductive film 33 is also called a touch panel sensor film, and is formed flat on the surface of the substrate body 31 by a conductive transparent member (for example, ITO), and the transparent electrode of the array substrate 12 Between these, a capacitive touch detection function is configured. The transparent conductive film 33 changes the capacitance between the transparent electrode of the array substrate 12 and the portion touched by the user with a finger or the like. The touched position can be detected. Accordingly, in the liquid crystal panel 11, the transmission component (Tx component) of the detection signal of the touch detection function is formed on the array substrate 12, and the reception component (Rx component) of the detection signal of the touch detection function is formed on the counter substrate 13. Yes. The common electrode may be formed on the array substrate 12 side depending on the mode of the liquid crystal layer 14. The color filter layer and the light shielding layer may be formed on the array substrate 12 side.

  Further, the liquid crystal layer 14 is sealed by being sealed with a sealing member that bonds the array substrate 12 and the counter substrate 13 in a rectangular frame shape, and is disposed at least at a position corresponding to the display region 17. As the liquid crystal layer 14, various modes such as a TN mode, an STN mode, a VA (MVA) mode, and an IPS mode can be used.

  The back polarizing plate and the front polarizing plate 16 are optical members each formed in a rectangular sheet shape, and are arranged so as to selectively transmit and block a predetermined polarized component according to the mode of the liquid crystal layer 14. ing. Further, a low resistance conductive film 36 which is a conductive film is formed on one main surface (front surface which is the front surface) of the front polarizing plate 16. The low-resistance conductive film 36 has translucency and covers one main surface of the entire front polarizing plate 16 in a flat shape. A projecting portion 37 is extended on one side (one corner) facing the connection region 24 of the front polarizing plate 16. The projecting portion 37 is formed in, for example, an elongated rectangular shape, and the distal end side extends to the flexible printed circuit board 26 across the connection region 24, and the copper foil tape 38 is used as an adhesive tape as a conductive tape member. Thus, it is fixed and electrically connected to a ground part 39 formed on one side of the flexible printed circuit board 26. That is, the projecting portion 37 is integrally connected to the flexible printed circuit board 26 and is folded back to the rear side of the liquid crystal panel 11 (array substrate 12) together with the flexible printed circuit board 26 and stored in a housing (not shown). Is done.

  Here, the copper foil tape 38 has conductivity on both sides, is formed in, for example, a rectangular shape, and intersects (orthogonally) the longitudinal direction of the protrusion 37 at the position of the tip of the protrusion 37. Are attached to the ground portion 39 of the flexible printed circuit board 26 with both end portions protruding from both side portions of the projecting portion 37.

  Further, the ground part 39 is set to the ground potential by being electrically connected to the ground potential of a circuit applied to the flexible printed circuit board 26, for example.

  The cover glass 18 is formed in a flat rectangular plate shape by a transparent member such as glass, and protects the liquid crystal panel 11 so that the user does not touch the liquid crystal panel 11 directly. The cover glass 18 is substantially the same size and shape as the array substrate 12 in plan view, or is formed larger than the array substrate 12, and the connection region 24 (circuit unit 25) between the counter substrate 13 and the array substrate 12 is formed. Covers the whole.

  Further, the resin layer 19 is configured by curing a fluid (liquid) adhesive 41 such as a thermosetting resin or an ultraviolet (UV) curable resin having translucency, and has a flat shape. A flat plate is interposed between the front polarizing plate 16 and the flat cover glass 18.

  Next, the operation of the one embodiment will be described.

  When the liquid crystal panel 11 is assembled, first, the array substrate 12 and the counter substrate 13 are formed in advance. The array substrate 12 is formed by repeatedly forming and patterning a conductive film or an insulating film on the substrate body 21 as appropriate to form an array pattern such as an image wiring section, a detection wiring section, a pixel electrode, a transparent electrode, and an alignment film. Form. In the counter substrate 13, a counter electrode, a color filter layer, a light shielding layer, an alignment film, and the like are formed on the substrate body 31 by appropriately repeating film formation and patterning of a conductive film or a resin film.

  Next, the formed substrates 12 and 13 are bonded together by a sealing member, and the liquid crystal layer 14 is sealed between the substrates 12 and 13. The liquid crystal layer 14 may be formed by adhering the substrates 12 and 13 in a state where the liquid crystal material is previously dropped on one of the substrates 12 and 13, or after the substrates 12 and 13 are adhered. It may be formed by injecting a liquid crystal material.

  Furthermore, the circuit unit 25 is mounted on the connection region 24 of the array substrate 12, and the terminal unit 28 of the flexible printed circuit board 26 is electrically connected by, for example, thermocompression bonding.

  Next, a back polarizing plate is attached to the rear side of the array substrate 12, and a front polarizing plate 16 having a low-resistance conductive film 36 is attached to the front side of the counter substrate 13. At this time, the front polarizing plate 16 is attached to the substrate body 31 of the counter substrate 13 with the low resistance conductive film 36 as the front side opposite to the counter substrate 13. In this state, the front polarizing plate 16 has the protruding portion 37 straddling the connection region 24 of the array substrate 12 and protrudes from the outer edge to the flexible printed circuit board 26 side.

  Further, the flexible printed circuit board 26 is folded back to the rear side of the array substrate 12, and the protruding portion 37 of the front polarizing plate 16 is attached to the ground portion 39 of the flexible printed circuit board 26 with the copper foil tape 38, thereby The low resistance conductive film 36 of the plate 16 is electrically connected to the ground part 39 through the copper foil tape 38. As a result, the front polarizing plate 16 (low resistance conductive film 36) is set to the ground potential.

  Then, a cover glass 18 is attached to the front polarizing plate 16. At this time, a fluid (liquid) adhesive 41 before curing is applied to the surface of the front polarizing plate 16, and a cover glass 18 is placed on the adhesive 41 to apply a predetermined pressure to the front polarizing plate 16 side. As a result, the adhesive 41 spreads uniformly. In this state, the cover glass 18 is bonded to the front polarizing plate 16 by curing the adhesive 41.

  According to the embodiment described above, the low-resistance conductive film 36 is provided on the surface, and the protruding portion 37 is protruded from the outer edge of the front polarizing plate 16 attached on the transparent conductive film 33 of the counter substrate 13, so that the ground potential and the electrical potential are increased. By connecting them to each other, it is possible to prevent the surface polarizing plate 16 from being charged, to prevent image display abnormalities due to the charging of the surface polarizing plate 16, and when forming this antistatic structure, for example, a separate member Unlike the case where the conductive member is used, the front side of the front polarizing plate 16 (low resistance conductive film 36), i.e., no unevenness is generated between the front polarizing plate 16 and the cover glass 18. When the cover glass 18 is applied to the front polarizing plate 16 and cured to attach the cover glass 18 to the front polarizing plate 16, the adhesive 41 spreads uniformly, and the flatness of the resin layer 19 can be secured, so that the pressing force becomes uniform. Not only is it difficult for air bubbles to enter, but the resin layer 19 is flat. Reduction of yield due to reduced can be effectively prevented.

  Further, the protrusion 37 of the front polarizing plate 16 is secured to the ground portion 39 of the flexible printed circuit board 26 using the copper foil tape 38 and is electrically connected, so that a connection space is made larger than necessary. The surface polarizing plate 16 (low resistance conductive film 36) can be easily set to the ground potential, and the fixing of the protruding portion 37 and the electrical connection to the ground portion 39 can be performed at once by fixing with the copper foil tape 38. The workability is also good.

  In the above-described embodiment, the protruding portion 37 can be protruded from the outer edge at an arbitrary position such as at least one of the side portions of the front polarizing plate 16.

  Although one embodiment of the present invention has been described, 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.

11 Liquid crystal panels as liquid crystal display elements
12 Array substrate
13 Counter substrate
14 Liquid crystal layer
16 A polarizing plate that is a polarizing plate
18 Cover glass as a protective plate
19 Resin layer as adhesive layer
26 Flexible printed circuit boards
33 Transparent conductive film
36 Low resistance conductive film
37 Protrusion
38 Copper foil tape as tape material
39 Ground
41 Adhesive

Claims (2)

A liquid crystal display element with a built-in capacitive touch detection function,
An array substrate;
A transparent conductive film that constitutes a touch detection function with the array substrate is provided on the surface, and a counter substrate disposed opposite to the array substrate in a state where the transparent conductive film is positioned on the opposite side of the array substrate;
A liquid crystal layer sealed between the array substrate and the counter substrate;
A polarizing plate provided with a conductive film on the surface and disposed on the transparent conductive film of the counter substrate;
A protective plate having translucency;
It is formed by curing a fluid adhesive, and includes an adhesive layer that bonds the protective plate and the polarizing plate,
The liquid crystal display element, wherein the polarizing plate includes a protruding portion protruding from an outer edge and electrically connected to a ground potential. A flexible printed circuit board comprising a ground portion set at a ground potential and electrically connected to the array board;
The conductive tape member which fixes the protrusion part of the said polarizing plate with respect to the said ground part of this flexible printed circuit board, and electrically connects the said electrically conductive film is comprised. The liquid crystal display element as described.

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