JP2011191444A - Liquid crystal display module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a glass substrate from breaking. <P>SOLUTION: In a liquid crystal display module, a surface light source device 31 has a point light source 35 and a light guide plate 34 in which an end surface protrudes in a thickness direction and the thickness of the protruding portion is larger than the thickness in a non-protruding portion. In a liquid crystal panel 61, a lower polarizing plate 66 is attached to the lower face of a glass substrate 63 in such a way that the polarizing plate is retreated from the end of the glass substrate 63 positioned in the lower face side out of a pair of glass substrates 62 and 63 sealing a liquid crystal. A light-shielding double-sided tape 39 is stuck to the upper face of the surface light source device 31 to produce a step between a region opposing to the point light source 35 and the protruding portion of the light guide plate 34 and a region opposing to the non-protruding portion. The lower polarizing plate 66 is adhered to the light-shielding double-sided tape 39 in the region corresponding to the non-protruding portion. The glass substrate 63 protruding from the end of the lower polarizing plate 66 opposes to the light-shielding double-sided tape 39 in the region corresponding to the point light source 35 and the protruding portion. The light-shielding double-sided tape 39 has a reduced adhesive strength in the region opposing to the glass substrate 63. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal display module, and more particularly to a liquid crystal display module including a liquid crystal panel and a backlight type surface light source device.

  As a liquid crystal display module in which a surface light source device and a liquid crystal panel are integrated using a double-sided tape, there is one disclosed in Patent Document 1.

  FIG. 1 is a cross-sectional view showing a liquid crystal display module disclosed in Patent Document 1. In FIG. In this liquid crystal display module, a liquid crystal panel 21 is stacked on a surface light source device 11. In the surface light source device 11, the light guide plate 12 is housed in a case 13, and a point light source 14 is provided at a position facing the end surface of the light guide plate 12. The one end portion of the light guide plate 12 has a large plate thickness as the surface on the light emitting side protrudes. On the non-projecting surface of the light guide plate 12, a diffusion plate 15 and a light collecting plate 16 are overlapped. Further, the end of the double-sided tape 17 is attached to the protruding surface of the light guide plate 12. The double-sided tape 17 has a window 18 for allowing light to pass through, and an edge portion of the window 18 is attached to the outer periphery of the light collector 16 to hold the light collector 16.

  The liquid crystal panel 21 has a polarizing plate 25 attached to the upper surface of a pair of glass substrates 23 and 24 encapsulating the liquid crystal 22, and a polarizing plate 26 attached to the lower surface.

  The liquid crystal panel 21 is assembled on the surface light source device 11 as shown in FIG. On the surface of the light guide plate 12, a step is provided between the protruding surface and the non-projecting surface, but the thickness of the light collector 16 is substantially equal to the step. Further, the end portions of the glass substrate 23 and the glass substrate 24 protrude from the ends of the polarizing plates 25 and 26. Therefore, the polarizing plate 26 on the lower surface side is overlaid on the light collector 16 with the non-projecting surface of the light guide plate 12, and the end of the glass substrate 24 projecting from the polarizing plate 26 is placed on the upper surface of the double-sided tape 17 attached to the projecting surface. When bonded, the glass substrate 24 is held on a substantially horizontal surface. Therefore, in the structure as disclosed in Patent Document 1, the polarizing plate 26 is placed on the non-projecting surface using the step on the surface of the light guide plate 12, so that the liquid crystal display module can be thinned.

JP 2002-98959 A

  However, in the liquid crystal display module of Patent Document 1, the liquid crystal panel 21 has only the lower surface of the protruding portion of the glass substrate 24 bonded to the protruding surface of the light guide plate 12 via the double-sided tape 17, and the other portion is a surface light source. It is only on the device 11 (on the non-projecting surface, the polarizing plate 26 is accommodated in the opening 18 of the double-sided tape 17 and is not bonded, but only on the light collector 16. ). Therefore, there is a problem that the glass substrates 24 and 23 of the liquid crystal panel 21 are easily broken.

  Moreover, recently, the end of the glass substrate 23 is shortened so that only the lower glass substrate 24 protrudes between the polarizing plates 25 and 26, and a driver IC is mounted on the upper surface of the glass substrate 24 by COG (chip on glass). In this case, the bonded portion of the liquid crystal panel 21 is a single glass substrate. Furthermore, as the liquid crystal display module is made thinner, the thickness of the glass substrates 23 and 24 itself tends to be thinner.

In the liquid crystal display module of Patent Document 1, the portion having the weakest strength for the liquid crystal panel 21 is bonded to the surface light source device 11 as described above, and therefore the following various points are problematic.
(1) Stresses due to handling during assembly and routing of flexible printed circuit boards are concentrated on the edges of weak glass substrates.
(2) The thickness of the polarizing plate 26 is matched with the step of the surface light source device 11 (the difference in height between the upper surface of the double-sided tape 17 and the light collector 16). Even when there is a gap between the upper surface of the glass substrate 24 and the lower surface of the glass substrate 24, the lower surface of the glass substrate 24 is forcibly adhered to the double-sided tape 17, so that stress is generated in the glass plate.
(3) Since the bonding area is relatively large and it is difficult to peel off at a single point, stress is concentrated when repairing.
(4) In order to solve these problems, there is originally a method of making a space between the double-sided tape 17 and the glass substrate 24. However, when the space is made, the surface light source device 11 and the liquid crystal panel 21 are now fixed. Can not be. Further, even if the liquid crystal panel 21 is fixed by any method, the end of the glass substrate 24 does not touch anywhere, so that it is vulnerable to vibration and impact.
As described above, in the structure as disclosed in Patent Document 1, the problem of strength cannot be avoided, which is a problem that cannot be avoided in reducing the thickness.

  The present invention has been made on the basis of the above-mentioned solution, and the object of the present invention is to make a liquid crystal display thinned by placing a part of the liquid crystal panel on the non-projecting surface of the surface light source device. An object of the present invention is to provide a liquid crystal display module having a structure in which the liquid crystal panel is not easily damaged.

  The liquid crystal display module according to the present invention is a liquid crystal display module in which a liquid crystal display panel is stacked on a surface light source device, and the surface light source device has an end surface protruding in a thickness direction, and the thickness of the protruding portion is A light guide plate having a thickness larger than the thickness of the non-projecting portion; and a light source disposed so as to face the end surface of the projecting portion of the light guide plate, wherein the liquid crystal panel is a pair of glass substrates sealed with liquid crystal An optical sheet is attached to the lower surface of the glass substrate on the lower surface side so as to be retracted from the edge of the glass substrate located on the lower surface side, and a light-shielding double-sided tape having a window opened in the light emitting region of the surface light source device, The optical sheet corresponds to the non-projecting part, and is attached to the upper surface of the surface light source device such that a step is generated between the region facing the light source and the projecting part of the light guide plate and the region facing the non-projecting part. The glass substrate on the lower surface side that is bonded to the light-shielding double-sided tape in a region and protrudes from the end of the optical sheet is opposed to the light-shielding double-sided tape in a region corresponding to the light source and the protruding portion, The adhesive strength is weak in a region facing the glass substrate on the lower surface side.

  In the liquid crystal display module of the present invention, the adhesive strength of a part of the light-shielding double-sided tape is weakened, and the portion extending longer than the optical sheet (polarizing plate etc.) of the liquid crystal display panel is low in the adhesive strength of the light-shielding double-sided tape. Since it is made to oppose the part, the part where the intensity | strength of the glass substrate of the lower surface side becomes weak easily is not adhere | attached on the surface light source device, or it adhere | attaches so that it may peel easily. For this reason, even if an impact or external force is applied to the liquid crystal display module, the glass substrate on the lower surface side is hardly damaged.

  An embodiment of the liquid crystal display module according to the present invention is characterized in that the light-shielding double-sided tape is weakened in adhesive strength by printing on a region facing the glass substrate. According to this embodiment, the adhesive strength of the light-shielding double-sided tape can be weakened easily. Further, the thickness of the liquid crystal display module is not increased as in the case where a resin sheet or the like is attached to the adhesive surface.

  In still another embodiment of the present invention, the sloped surface of the light-shielding double-sided tape is located between the region corresponding to the non-projecting part and the region corresponding to the light source and the projecting part, It is characterized in that the adhesive strength of the part is changed. According to such an embodiment, the glass substrate on the lower surface side is shielded on both sides even if the position where the light-shielding double-sided tape is attached to the surface light source device varies somewhat or there is some variation in the area where the adhesive strength of the light-shielding double-sided tape is weakened. Bonding to the tape can be prevented.

  The means for solving the above-described problems in the present invention has a feature in which the above-described constituent elements are appropriately combined, and the present invention enables many variations by combining such constituent elements. .

FIG. 1 is a partially broken cross-sectional view of a liquid crystal display module disclosed in Patent Document 1. FIG. 2 is a partially cutaway cross-sectional view of a liquid crystal display module according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of the surface light source device used in the liquid crystal display module of the embodiment. FIG. 4 is a plan view of the above surface light source device.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, and various design changes can be made without departing from the gist of the present invention.

  FIG. 2 is a partially cutaway cross-sectional view of a liquid crystal display module according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of the surface light source device 31 used in the liquid crystal display module.

  The liquid crystal display module includes a surface light source device 31 and a liquid crystal panel 61.

  As shown in FIG. 3, the surface light source device 31 includes a reflector 32, a frame 33, a light guide plate 34, a plurality of point light sources 35, a flexible printed board 36, a diffuser plate 37, two prism sheets 38a and 38b, a light shield. It consists of a double-sided tape 39 or the like.

  As shown in FIG. 2, in the point light source 35 (light emitting element), the surface excluding the front surface of the resin 34 containing the phosphor is covered with the white resin 35. Therefore, when the blue light emitting LED chip 33 emits light, the light emitted from the LED chip 33 is emitted to the outside from the front surface (light emitting window) of the resin 34 while being converted into pseudo white light. A part of the light emitted from the LED chip 43 is reflected at the interface between the transparent resin 44 and the white resin 45 and then emitted from the front surface of the transparent resin 44 to the outside. As the point light source 35, for example, NSSW204 (thickness 0.4 mm) manufactured by Nichia Corporation can be used.

  These point light sources 35 are mounted on the lower surface of a flexible printed circuit board 36 (for example, a thickness of 0.1 mm), and are arranged in a line at a constant pitch.

  The light guide plate 34 is formed into a plate shape using a light-transmitting resin having a high refractive index, such as polycarbonate resin or polymethyl methacrylate (PMMA) resin. A light incident surface 41 for introducing light into the light guide plate 34 is formed on the end surface of the light guide plate 34. On the upper surface of the light guide plate 34, the edge on the light incident surface 41 side protrudes upward, and the light incident side edge of the light guide plate 34 is a light introducing portion 51 having a large thickness. The light guide plate main body 52 located on the side farther from the light incident surface 41 than the light introducing portion 51 is thinner than the light introducing portion 51, and the angle between the end of the light introducing portion 51 and the end of the light guide plate main body 52 is inclined. Connected by the surface 53. For example, the thickness of the light introduction part 51 is 0.43 mm, and the thickness of the light guide plate main body 52 is 0.20 mm. Therefore, the light introduction part 51 has a thickness substantially equal to the thickness of the point light source 35, and can efficiently take the light emitted from the point light source 35 into the light guide plate 34. In addition, the light guide plate main body 52 occupying most of the light guide plate 34 is thinner than the thickness of the point light source 35, which contributes to the thinning of the surface light source device 31. The upper surface of the light guide plate main body 52 is a light emitting surface 42, and the lower surface of the light guide plate 34 is finely deflected so as to totally reflect the light guided through the light guide plate 34 and emit the light upward from the light emitting surface 42. A large number of patterns 40 (diffusion means) are formed.

  Accordingly, the light emitted from the point light source 35 is introduced into the light guide plate 34 from the light incident surface 41 of the light introducing portion 51. The light in the light introduction part 51 is reflected by the inclined surface 53 or its lower surface, or directly sent to the light guide plate main body 52. The light in the light guide plate main body 52 is guided through the light guide plate 34 while repeating total reflection between the upper surface (light emitting surface 42) and the lower surface of the light guide plate 34. The light totally reflected or diffused by the deflection pattern 40 in the middle of the light guide is emitted from the light emitting surface 42 to the outside.

  The frame 33 is obtained by cutting a resin sheet (polycarbonate resin sheet) having the same thickness as the light introducing portion 51 of the light guide plate 34 and has an opening 46 for positioning the light guide plate 34. ing. In addition, recesses 47 for positioning the point light source 35 mounted on the lower surface of the flexible printed circuit board 36 are provided at the end of the opening 46 at the same pitch as the point light source 35.

  The reflector 32 is made of a material having high reflectivity such as a white sheet or a metal foil, and is attached to the lower surface of the frame 33 by a reflector tape 49a. The reflection plate 32 reflects light leaking from the lower surface of the light guide plate 34 and re-enters the light guide plate 34 to improve the light use efficiency. As the reflecting plate 32, for example, 3M ESR (thickness: 0.065 mm) can be used. As the reflector tape 49a, Teraoka Seisakusho # 707 (thickness 0.03 mm) can be used.

  The light-shielding double-sided tape 39 is obtained by applying an adhesive to both the front and back surfaces of a black base material. The light-shielding double-sided tape 39 has a window 48 opened to expose the prism sheet 38b and the like. However, the window 48 is slightly smaller in size than the prism sheet 38b. Further, although the adhesive is adhered as it is on the entire lower surface of the light-shielding double-sided tape 39, the adhesive contact of the adhesive is performed on the upper surface by subjecting the area contacting the glass substrate 63 of the liquid crystal panel 61 to a paste-killing process as will be described later. Reduced or completely eliminated. For example, 7045 (0.05) black HF (thickness 0.05 mm) manufactured by Teraoka Seisakusho can be used as the light-shielding double-sided tape 39 before the paste killing process is performed.

  Paste-killing is a method of neutralizing the adhesive and erasing the adhesive force by applying ink to the adhesive surface of the adhesive tape (shielded double-sided tape) by screen printing, etc. It is so thin that it can be ignored. As a method for preventing the light-shielding double-sided tape 39 from sticking to the glass substrate 63 of the liquid crystal panel 61, it is possible not to apply the adhesive to the region, but rather than not applying the adhesive only to the predetermined region. However, it is easier to paste only by printing in a predetermined area after applying with an adhesive. Further, the pressure-sensitive adhesive has a thickness of about 30 μm, while the paste-killing printed layer has a thickness of about 1 μm, so that a step is hardly formed on the surface of the light-shielding double-sided tape 39. Such a paste killing method is disclosed in, for example, Japanese Patent Laid-Open No. 2006-69045.

  As shown in FIG. 2, the upper surface of the outer peripheral portion of the reflecting plate 32 is attached to the lower surface of the frame 33 by the reflecting plate tape 49a. Then, the light guide plate 34 is placed in the opening 46 of the frame 33, and the point light source 35 is placed and positioned in each recess 47 so that the front surface of each point light source 35 faces the light incident surface 41 of the light guide plate 34. The lower surface of the flexible printed circuit board 36 is bonded to the upper surface of the frame 33 and the upper surface of the light introducing portion 51 by an adhesive tape 49b (for example, Nitto Denko No. 5603, thickness 0.03 mm). Therefore, the end portion of the light guide plate 34 is held between the reflection plate 32 and the flexible printed board 36.

  Further, a diffusion plate 37 and two prism sheets 38 a and 38 b are placed on the light emitting surface 42 of the light guide plate 34, and the edges are pressed by the light-shielding double-sided tape 39. The prism sheets 38a and 38b are obtained by arranging linear prism patterns having a triangular cross section on the surface in parallel at a constant pitch, but the prism sheets 38a and 38b are overlapped so that the arrangement directions of the patterns are orthogonal to each other. Yes. The light shielding double-sided tape 39 is attached to the upper surface of the flexible printed circuit board 36, the edge of the prism sheet 38b, and the upper surface of the frame 33. The diffusion plate 37 and the prism sheets 38a, 38b are held by the light shielding double-sided tape 39. For example, Duji S 120 (0.095 mm) manufactured by Tsujiden can be used as the diffusion plate 37, and TBEF (thickness 0.065 mm) manufactured by 3M can be used as the prism sheets 38a and 38b.

  The liquid crystal panel 61 has a liquid crystal 64 sealed between a glass substrate 62 (color filter glass) having a color filter formed on the inner surface and a glass substrate 63 (TFT glass) having a TFT formed on the inner surface. The upper polarizing plate 65 is pasted on the upper surface of the glass substrate 62, and the lower polarizing plate 66 is pasted on the lower surface of the glass substrate 63. The lower glass substrate 63 protrudes from the ends of the upper polarizing plate 65 and the glass substrate 62 and extends longer. On the contrary, the lower polarizing plate 66 is shorter than the ends of the upper polarizing plate 65 and the glass substrate 62. . Further, a driver chip 67 for a liquid crystal panel is COG mounted on a portion of the glass substrate 63 that extends longer than the glass substrate 62.

  An adhesive is applied to the entire lower surface of the light shielding double-sided tape 39, and the light shielding double-sided tape 39 is attached to the upper surface of the flexible printed circuit board 36 and the upper surface of the frame 33. The light-shielding double-sided tape 39 attached from the frame 33 to the upper surface of the flexible printed circuit board 36 is bent or curved so as to follow the shape of the upper surface of the light guide plate 34, resulting in a step. That is, above the light guide plate main body 52, the upper surface of the light-shielding double-sided tape 39 is lowered, the lower surface of the edge of the window 48 is adhered to the edge of the prism sheet 38b, and the diffuser plate 37 and the prism sheets 38a and 38b are Is retained.

  As shown in FIG. 2, in the liquid crystal panel 61, the upper polarizing plate 65 is accommodated in a position one step lower above the light guide plate body 52, and the horizontally extending portion of the glass substrate 63 is overlaid on the flexible printed circuit board 36. In this way, it is superimposed on the upper surface of the surface light source device 31 (the upper surface of the light-shielding double-sided tape 39). The gap (in the thickness direction) between the lower surface of the horizontally extending portion of the glass substrate 63 and the upper surface of the light-shielding double-sided tape 39 facing this surface is the light-shielding double-sided tape 39 due to the dimensional tolerance of each member. In view of mass productivity, it is desirable to design so as to be equal to or greater than an error in the thickness direction of the upper surface (height error). When the gap is smaller than the error in the thickness direction of the upper surface of the light-shielding double-sided tape 39 due to the dimensional tolerance of each member, the error in the height of the upper surface of the light-shielding double-sided tape 39 is maximized (that is, When the lower surface of the glass substrate 63 is lower than the upper surface of the light-shielding double-sided tape 39), the glass substrate 63 continues to receive external force so that the lower surface of the glass substrate 63 is flipped up by the upper surface of the light-shielding double-sided tape 39. Since the stress remains applied, the glass substrate 63 is easily damaged. On the other hand, if there is a gap larger than the error in the thickness direction of the upper surface of the light shielding double-sided tape 39 due to the dimensional tolerance of each member, the glass substrate 63 may be pushed up to the upper surface of the light shielding double-sided tape 39 and may be damaged. Less. However, if all the members have dimensions as designed, there is no problem even if the gap is designed to be zero.

  FIG. 4 shows the upper surface of the surface light source device 31. A dividing line A shown in FIG. 4 shows a portion of the light-shielding double-sided tape 39 that is bent obliquely downward from a plane parallel to the flexible printed circuit board 36 as shown in FIG. 52. The boundary C between the area 69 and the area B is defined between the area 69 and the area 68 where the adhesive 68 is applied for the following reason. It is fixed on the slope. The area facing the lower surface of the glass substrate 63 is a paste-killing area 69 and does not stick, but the area shown by the satin hatching is coated with an adhesive 68 and has adhesiveness. The area 69 of the paste killing process may be only where the lower surface of the glass substrate 63 touches, but the adhesive 68 may stick to the glass substrate 63 due to variations when the light-shielding double-sided tape 39 is applied. Further, when the paste-killing region 69 reaches the bonding region of the lower polarizing plate 66 due to variation, a part of the lower polarizing plate 66 is not bonded, and the bonding strength between the liquid crystal panel 61 and the surface light source device 31 is reduced. There is a risk of too much. Therefore, in this embodiment, as shown in FIG. 4, a light-shielding double-sided tape that does not touch the glass substrate 63 nor the lower polarizing plate 66 at the boundary C between the paste-killing region 69 and the region coated with the adhesive 68. 39 slopes are defined.

  Further, as shown in FIG. 4, the lower polarizing plate 66 has a size that does not enter the opening of the light-shielding double-sided tape 39, and the lower surface of the lower polarizing plate 66 is adhered to the periphery of the window 48 with an adhesive 68. . Therefore, the liquid crystal panel 61 is fixed to the surface light source device 31 on the lower surface of the lower polarizing plate 66, and the horizontally extending portion of the glass substrate 63 having low strength is not fixed at all.

  In the liquid crystal display module of the present invention, because of the above structure, the glass substrate 63 (TFT glass) is difficult to break. That is, since the weak portion of the glass substrate 63 is not adhered to the light-shielding double-sided tape 39 of the surface light source device 31, the surface light source device 31 and the like are used when assembling the liquid crystal display module or when incorporating the liquid crystal display module into a mobile phone or the like. Even if stress is applied, the extending portion of the glass substrate 63 is not fixed and therefore does not break. Further, since the light-shielding double-sided tape 39 is only in contact with the glass substrate 63, the vibration of the glass substrate 63 is not affected even when an impact is applied to the liquid crystal display module in the assembled state. Since it is suppressed by the tape 39, the glass substrate 63 is hardly broken.

  The liquid crystal panel 61 is bonded to the surface light source device 31 in a region along the periphery of the window 48 of the light-shielding double-sided tape 39. Since this adhesion region is very thin and has a small area, when repairing the liquid crystal display module, the liquid crystal panel 61 is easily peeled off from the surface light source device 31, and the possibility of the liquid crystal panel 61 being damaged when being peeled is reduced.

  Furthermore, according to the structure of the liquid crystal display module of the present invention, the strength of the liquid crystal display module can be improved without increasing the thickness of the liquid crystal panel 61. That is, erasing the adhesiveness of a part of the light-shielding double-sided tape 39 can be realized by attaching a sheet of PET or the like to a part of the adhesive surface. However, if PET is attached to the light-shielding double-sided tape 39, the thickness becomes at least several tens of μm, which obstructs the thinning of the liquid crystal display module. On the other hand, in the present invention, since the tacky erasing is performed by printing (a paste-killing process), an increase in thickness is hardly a problem.

Claims (3)

A liquid crystal display module in which a liquid crystal display panel is superimposed on a surface light source device,
The surface light source device is disposed so that the surface of the end portion protrudes in the thickness direction and the thickness of the protruding portion is larger than the thickness of the non-projecting portion, and the protruding portion end surface of the light guide plate. Light source,
The liquid crystal panel has an optical sheet attached to the lower surface of the glass substrate on the lower surface side so as to be retracted from the end of the glass substrate located on the lower surface side of the pair of glass substrates sealed with liquid crystal,
The light-shielding double-sided tape whose window is opened in the light emitting region of the surface light source device is configured so that a step is generated between the region facing the light source and the projecting portion of the light guide plate and the region facing the non-projecting portion. Paste it on the top of the light source device,
The optical sheet is bonded to the light-shielding double-sided tape in a region corresponding to the non-projecting part, and the glass substrate on the lower surface side projecting from the end of the optical sheet is attached to the light source and the light-shielding double-sided tape in a region corresponding to the projecting part. Facing
The light-shielding double-sided tape has a weak adhesive strength in a region facing the glass substrate on the lower surface side.   The liquid crystal display module according to claim 1, wherein the light-shielding double-sided tape is weakened in adhesive strength by printing on a region facing the glass substrate.   In the light-shielding double-sided tape, an adhesive strength of the slope portion is changed in a slope portion located between a region corresponding to the non-projecting portion and a region corresponding to the light source and the projecting portion. The liquid crystal display module according to claim 1.

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