JP2014178551A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which suppresses local changes in a gap between substrates caused by a stress generating by bending of a flexible printed circuit board.SOLUTION: A liquid crystal display device 11 includes a liquid crystal panel 12, a cover glass 15, and a double-sided tape 38. The liquid crystal panel 12 includes substrates 21, 22 disposed opposing to each other via a predetermined gap G. The liquid crystal panel 12 includes a liquid crystal layer 23 sealed in the gap G between the substrates 21, 22. The liquid crystal panel 12 includes a flexible printed circuit board 25. The flexible printed circuit board 25 is mounted, at one end 25a portion, on one major surface 31a of the array substrate 21 on the counter substrate 22 side, and is folded and turned at the other end 25b portion to the opposite side of the array substrate 21 with respect to the counter substrate 22. The cover glass 15 is positioned and fixed on the counter substrate 22 side of the liquid crystal panel 12. The double-sided tape 38 adheres and fixes the flexible printed circuit board 25 to the cover glass 15.

Description

  Embodiments described herein relate generally to a liquid crystal display device having a liquid crystal display element including a flexible substrate.

  Conventionally, liquid crystal display devices are widely used as flat display devices, that is, flat panel displays (FPDs). For example, a transmissive liquid crystal display device includes a liquid crystal panel as a liquid crystal display element (liquid crystal cell), and a backlight that irradiates planar light on the back side of the liquid crystal panel. The liquid crystal panel is configured by interposing a liquid crystal layer, which is a light modulation layer, between the array substrate and the counter substrate, and the flexible printed circuit board is electrically and mechanically connected to terminals located at the end of the array substrate. And are electrically connected to an external circuit through the flexible printed circuit board.

  In such a liquid crystal panel, display unevenness occurs due to a local change in the gap between the array substrate and the counter substrate. The change in the gap is mainly caused by, for example, the expansion of the liquid crystal material, the deformation of the glass substrate constituting the array substrate and the counter substrate, or the stress generated by the bending of the flexible printed circuit board. Has been.

  As a method of reducing gap unevenness, generally, a method of reducing the amount of liquid crystal material to prepare for expansion under high temperature, or a buffer material (spacer) is interposed between the liquid crystal panel and the backlight. There is a method of making it difficult to transmit the stress (reaction force) generated by bending the flexible printed circuit board to the glass substrate of the array substrate.

  However, if the amount of the liquid crystal material is reduced too much, another problem such as generation of bubbles at a low temperature may occur. In addition, when a buffer material is interposed between the liquid crystal panel and the backlight, it may not be possible to secure sufficient strength against stress.

JP 2001-209054 A

  The problem to be solved by the present invention is to provide a liquid crystal display device in which a local change in a gap between substrates due to a stress generated by bending a flexible substrate is suppressed.

  The liquid crystal display device of the embodiment includes a liquid crystal display element, a structure, and an adhesive. The liquid crystal display element includes one and the other substrates arranged to face each other with a predetermined gap. The liquid crystal display element includes a liquid crystal layer sealed in a gap between the substrates. Furthermore, the liquid crystal display element includes a flexible substrate. One end of this flexible substrate is mounted on one main surface located on the other substrate side of one substrate, and the other end is folded back to the opposite side of the one substrate with respect to the other substrate. The structure is fixed on the other substrate side of the liquid crystal display element. The adhesive body adheres and fixes the flexible substrate to the structure.

It is explanatory drawing which shows typically the bending state of the one part flexible substrate of the liquid crystal display device of one Embodiment. It is explanatory drawing which shows typically a part of liquid crystal display device same as the above. It is a top view which shows a part of liquid crystal display device same as the above.

  Hereinafter, the configuration of an embodiment will be described with reference to FIGS. 1 to 3.

  1 to 3, reference numeral 11 denotes a liquid crystal display device (liquid crystal module). The liquid crystal display device 11 is arranged on a liquid crystal panel 12 which is a liquid crystal cell as a liquid crystal display element, and on the back side of the liquid crystal panel 12. Backlight 13, a structure 14 arranged on the display side of the liquid crystal panel 12, a cover glass 15 for protection as a structure that covers and protects the structure 14, and a housing frame that is a set housing 16, for example, has a quadrangular shape in plan view. Hereinafter, the display side (lower side in FIG. 1) of the liquid crystal panel 12 will be described as the front side, and the opposite side (upper side in FIG. 1) will be described as the back side, that is, the rear side.

  The liquid crystal panel 12 includes a transmission type that transmits planar light from the backlight 13 to display an image, or a transmission unit that transmits planar light from the backlight 13 and a reflection unit that reflects incident light from the front side. And a transflective type with an active matrix type. The liquid crystal panel 12 includes an array substrate 21 as one of the quadrangular substrates and a counter substrate 22 as the other quadrangular substrate having a predetermined gap (cell gap) G with the array substrate 21 as the front side. A liquid crystal layer 23 that is a light modulation layer between the substrates 21 and 22 and a spacer (not shown) that holds a gap between the substrates 21 and 22 are interposed to seal the substrates 21 and 22 with each other. The flexible printed circuit board (FPC) 25, which is a flexible substrate, is mounted on the array substrate 21, and a polarizing plate (not shown) is attached to the rear side of the array substrate 21 and the front side of the counter substrate 22, respectively. An active area that can display an image, that is, a display area 26 is formed in a quadrangular shape.

  The array substrate 21 includes a glass substrate 31 that is a single glass portion as one substrate body, a plurality of wiring portions (not shown) formed in a lattice shape at positions corresponding to the display area 26 on the glass substrate 31, and a glass substrate The display area 26 includes a pixel electrode (not shown) that forms a pixel, a thin film transistor (TFT) that is a switching element that drives the pixel electrode, and the like. In addition, a drive circuit 27 for driving each thin film transistor is mounted on the array substrate 21 in a drive region 28 which is a peripheral connection region located outside the display region 26, and is electrically connected to a wiring unit or the like. ing. The drive region 28 is formed at a position on the glass substrate 31 of the array substrate 21 that does not face the counter substrate 22, in other words, a position that protrudes outward from the counter substrate 22.

  The counter substrate 22 includes a glass substrate 33 as the other substrate body, a counter electrode (not shown) that is a common electrode formed on the glass substrate 33, a color filter layer, and the like. The common electrode may be formed on the array substrate 21 side depending on the mode of the liquid crystal layer 23. The color filter layer may be formed on the array substrate 21 side.

  As the liquid crystal layer 23, for example, various modes such as a TN mode, an STN mode, a VA (MVA) mode, and an IPS mode can be used.

  The seal member 24 is formed in a rectangular frame shape surrounding the liquid crystal layer 23 with, for example, an ultraviolet curable resin.

  Each polarizing plate is an optical member formed in a sheet shape, and is arranged so as to selectively transmit and block a predetermined polarization component according to the mode of the liquid crystal layer 23.

  The flexible printed circuit board 25 electrically connects, for example, the drive circuit 27 and an external circuit (not shown). For example, an anisotropic conductive film (ACF) (not shown) is disposed on one main surface 31a of the flexible printed circuit board 25 on the front side which is the counter substrate 22 side of the glass substrate 31 in the driving region 28. And are electrically and mechanically connected through thermocompression. Further, the other end 25b side of the flexible printed circuit board 25 is folded back to the rear side opposite to the counter substrate 22 of the glass substrate 31 of the array substrate 21, in this embodiment, the liquid crystal panel 12 and the back surface. The backlight 13 is electrically and mechanically connected to an external circuit located on the back side of the backlight 13 in a state of being folded back to the back side of the light 13, and is connected via a fixing member (not shown) such as a double-sided tape. It is fixed to the support frame. The drive circuit 27 may be mounted on the flexible printed board 25.

  The backlight 13 includes a light source, a rectangular plate-shaped light guide plate as a light guide body that converts light from the light source into planar light, a plurality of optical sheets arranged on the front side of the light guide plate, and a light guide plate It is composed of a reflection sheet disposed on the rear side and a support frame that supports the light source and the light guide plate, and irradiates the rear side of the liquid crystal panel 12 with planar light. The backlight 13 has a support frame on both sides of the liquid crystal panel 12 (the other main surface 31b opposite to the one main surface 31a of the glass substrate 31 of the array substrate 21) at the front position facing the liquid crystal panel 12. It is fixed by a fixing body 35 such as a tape. The support frame may be integrated with the housing frame 16 or may be separate.

  For example, a light emitting diode (LED) or the like is used as the light source, and is disposed to face one side of the light guide plate.

  The light guide plate is disposed opposite to the rear side of the liquid crystal panel 12, and at the outer end portion thereof, the display region 26 and the liquid crystal are arranged so that at least a region corresponding to the entire display region 26 of the liquid crystal panel 12 can be irradiated. The panel 12 extends outward from the outer end portion.

  The optical sheet is, for example, a diffusion sheet that diffuses light emitted from the light guide plate, a prism sheet that collects light diffused by the diffusion sheet, or a polarization separation sheet.

  The reflection sheet reflects light to be emitted from the rear side of the light guide plate and emits the light from the front side of the light guide plate.

  The structure 14 uses, for example, a touch panel for a user to input a touch operation based on an image displayed on the display area 26 of the liquid crystal panel 12, and the front side of the liquid crystal panel 12, that is, the counter substrate 22 (front side polarization). It is fixed to the front side of the plate. The structure 14 is not an essential component, and the cover glass 15 may be directly fixed to the liquid crystal panel 12.

  The cover glass 15 is, for example, a rectangular protection member that protects the user from touching the liquid crystal panel 12 and the structure 14 directly. The cover glass 15 is formed to be thicker than the glass substrate 31 of the array substrate 21 or the glass substrate 33 of the counter substrate 22, for example. Further, the outer end portion of the cover glass 15 protrudes outward with respect to the outer end portion of the liquid crystal panel 12 (the array substrate 21 and the counter substrate 22), and the liquid crystal panel is projected at the protruding position. The main surface 25c opposite to the array substrate 21 (one main surface 31a of the glass substrate 31) of the flexible printed circuit board 25 on the main surface 15a on the rear side which is the 12 (structure 14) side is an adhesive body having elasticity. The adhesive is fixed through a double-sided tape 38. For example, the main surface 15a of the cover glass 15 may be provided with various decorations such as printing.

  For example, the double-sided tape 38 is adjusted to have a thickness approximately the same as the distance between the main surface 31a of the glass substrate 31 of the array substrate 21 and the main surface 15a of the cover glass 15. Further, the double-sided tape 38 is positioned near the one end 25a of the flexible printed circuit board 25 and at a position outside the array substrate 21 (glass substrate 31), in this embodiment, the array substrate 21 (glass substrate 31). It is arranged at a position near the end face. The double-sided tape 38 may be provided continuously or intermittently on the entire portion of the main surface 15a of the cover glass 15 and the main surface 25c of the flexible printed board 25 facing each other, or provided on a part thereof. May be.

  The housing frame 16 is made of, for example, synthetic resin or metal, is formed in a rectangular frame shape, and surrounds the outside of the liquid crystal panel 12 and the backlight 13 in a frame shape.

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

  When assembling the liquid crystal display device 11, first, the liquid crystal panel 12 and the backlight 13 are each assembled appropriately. The liquid crystal panel 12 is sealed with a sealing member 24 with a liquid crystal layer 23 interposed between substrates 21 and 22 formed separately, and a drive circuit 27 and a flexible printed circuit board 25 are mounted. In the backlight 13, an optical sheet is stacked on the light guide plate and fixed to the support frame, and a reflection sheet is attached to the support frame.

  Next, the structure 14 and the cover glass 15 are sequentially bonded to the liquid crystal panel 12 and fixed. At this time, the main surface 25c of the flexible printed circuit board 25 is adhesively fixed to the main surface 15a of the cover glass 15 using a double-sided tape 38 at a position near the one end 25a of the flexible printed circuit board 25. Further, the liquid crystal panel 12 and the backlight 13 to which the structure 14 and the cover glass 15 are bonded are bonded together by the fixed body 35 and assembled to the housing frame 16.

  Then, the other end 25b side of the flexible printed circuit board 25 protruding from the housing frame 16 is folded back to the rear side of the backlight 13 (housing frame 16) and connected to an external circuit, and then the other parts are assembled. The liquid crystal display device 11 is completed.

  When the liquid crystal display device 11 thus completed is connected to a power source, the light from the light source is converted into planar light by the light guide plate, and then the planar light is transmitted to the rear of the liquid crystal panel 12 through the optical sheet. Irradiate to the side.

  In the liquid crystal panel 12, the pixel is driven corresponding to the image to be displayed, the polarization direction of the planar light incident through the rear polarizing plate is converted, and the amount of light transmitted through the front polarizing plate (transmission amount) ) Is set for each pixel, the light passing through the structure 14 and the cover glass 15 is visually recognized by the user as an image.

  According to the embodiment described above, the flexible printed circuit board 25 is adhesively fixed by the double-sided tape 38 to the cover glass 15 positioned and fixed on the front side which is the counter substrate 22 side of the liquid crystal panel 12. When the liquid crystal display device 11 is assembled, when the other end 25b side of the flexible printed circuit board 25 is folded back (folded), the flexible printed circuit board 25 is caused to return and deform relatively toward the front side. The stress (reaction force) F to be received is received by the double-sided tape 38, and this stress F can be hardly transmitted to the array substrate 21 (glass substrate 31) via the flexible printed circuit board 25. Accordingly, the deformation and inclination of the array substrate 21 (glass substrate 31) due to the stress F as shown by the imaginary line in FIG. 1 can be suppressed, so that the liquid crystal material constituting the liquid crystal layer 23 can be reduced or the liquid crystal panel 12 can be reduced. Without attaching a buffer material for suppressing the stress F between the light source and the backlight 13, local changes (gap unevenness) in the gap G between the substrates 21 and 22 caused by the stress F can be suppressed. . Therefore, it is possible to prevent the occurrence of defects (low-temperature bubbles, etc.) due to the weight loss of the liquid crystal material, the design of the cushioning material is unnecessary, the manufacturability is improved, and the display unevenness due to the local change of the gap G is prevented. As a result, the display quality of the liquid crystal display device 11 can be secured.

  Further, the thickness of the double-sided tape 38 is set to the same thickness as the distance between the array substrate 21 (one main surface 31a of the glass substrate 31) and the cover glass 15 (main surface 15a), so that the double-sided tape 38 Therefore, the stress F can be received more reliably.

  Further, the double-sided tape 38 is adhesively fixed to the cover glass 15 at a position near the one end 25a of the flexible printed circuit board 25 at a position near the end face of the position corresponding to the drive region 28 of the array substrate 21 (glass substrate 31). Therefore, compared with the case where the double-sided tape 38 is arranged apart from the end surface at the position corresponding to the drive region 28 of the array substrate 21 (glass substrate 31) or the other end 25b side of the flexible printed circuit board 25, the stress is reduced. F can be received more effectively.

  In the above-described embodiment, the structure that adheres and fixes the flexible printed circuit board 25 with the double-sided tape 38 is not limited to the cover glass 15, but an arbitrary structure that is fixed to the front side (opposite substrate 22 side) of the liquid crystal panel 12. The body can be used.

  Further, the adhesive body is not limited to the double-sided tape 38, and any adhesive substance can be used.

  Furthermore, the liquid crystal display device 11 is not limited to a rectangular shape, and may be, for example, a circular shape. In this case, it can be dealt with by making various components into a circular shape.

  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 display
12 Liquid crystal panels as liquid crystal display elements
15 Cover glass as a structure
21 Array substrate as one substrate
22 Counter substrate as the other substrate
23 Liquid crystal layer
25 Flexible printed circuit boards that are flexible substrates
25a one end
25b other end
31a Main surface
38 Double-sided tape as adhesive G G

Claims (1)

One and the other substrates arranged opposite to each other with a predetermined gap, a liquid crystal layer sealed in the gap between the substrates, and one end on one main surface located on the other substrate side of the one substrate A liquid crystal display element comprising a flexible substrate mounted on the other side of the one substrate and the other side folded back to the opposite side of the other substrate;
A structure positioned and fixed on the other substrate side of the liquid crystal display element;
A liquid crystal display device comprising: an adhesive body that adheres and fixes the flexible substrate to the structure.

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