JP4801246B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a backlight integrated liquid crystal display device in which a backlight is disposed between a liquid crystal display element and a power supply side wiring substrate.
[0002]
[Prior art]
First, an example of a general liquid crystal display element in this type of liquid crystal display device will be described with reference to FIG.
[0003]
FIG. 5 shows a displayable liquid crystal display element 10 mounted on a liquid crystal display device, and has two transparent substrates 1A and 1B arranged substantially in parallel with a distance therebetween. The outer periphery between the two transparent substrates 1A and 1B is sealed with a sealing material 2, and a transparent common electrode 3A is disposed in close contact with the lower surface of one transparent substrate 1A located above. A light shielding film 4 is disposed below the transparent common electrode 3A so as to cover a non-display portion of the liquid crystal display element 10.
[0004]
Below the light-shielding film 4, an alignment film 6A that controls the alignment of liquid crystal molecules according to the voltage applied between the electrodes is disposed in close contact with the transparent substrate 1A. A polarizing plate 7A is provided.
[0005]
On the other hand, a transparent segment electrode 3B is disposed on the upper surface of the transparent substrate 1B located below, and a color filter film 5 is disposed above the transparent segment electrode 3B. An alignment film 6B is disposed on the upper side so as to be in close contact therewith. Further, a polarizing plate 7B is disposed on the lower surface of the transparent substrate 1B.
[0006]
A liquid crystal 8 is sealed in a sealed space surrounded by the transparent substrates 1A and 1B and the sealing material 2, and a plurality of spherical or columnar spacers 9 interposed between the alignment films 6A and 6B. The transparent substrates 1A and 1B are held at a constant interval.
[0007]
The transparent segment electrode 3B on the upper surface of the transparent substrate 1B is led out on the lower surface of the transparent substrate 1A via a conductive member (not shown) contained in the sealing material 2 and the like. Each lead terminal 3C of each electrode 3A, 3B is formed in the right end part in FIG. 1 of the lower surface of this transparent substrate 1A.
[0008]
On the other hand, an electric circuit 13 is formed on the base film 12 of the flexible wiring board 11, and each lead terminal 3C of each of the electrodes 3A and 3B is connected to a terminal (not shown) formed at the end of the electric circuit 13. Is connected. An LSI 14 for controlling the liquid crystal display element 10 is connected to the electric circuit 13 of the flexible wiring board 11. The flexible wiring board 11 is formed with a curved portion 15 to reduce the plane area of the liquid crystal display device, and then extends below the liquid crystal display element 10 as shown in FIG. It is electrically connected to the power supply side wiring board 16 having rigidity positioned below the liquid crystal display element 10.
[0009]
Incidentally, in the backlight-integrated liquid crystal display device, a backlight point light source 17 such as a light emitting diode or a fluorescent lamp is supported on one end portion of the upper surface of the power supply side wiring substrate 16 facing the liquid crystal display element 10. Yes.
[0010]
A light guide body 20 having a light guide plate 18 made of a material such as acrylic and a guide frame 19 for supporting the light guide plate 18 is mounted on the upper surface of the power supply side wiring board 16. At the time of mounting, the point light source 17 is positioned on the side of the end face of the light guide 20.
[0011]
In the liquid crystal display device shown in FIG. 6, a plurality of prism sheets 21 are disposed on the upper surface of the light guide plate 18, and the light guide 20 is configured together with the light guide plate 18 and the guide frame 19. is doing.
[0012]
The light guide 20 and the liquid crystal display element 10 are bonded by an adhesive sheet 22 as an adhesive member formed in a substantially rectangular frame shape surrounding the display area of the liquid crystal display element 10 in the liquid crystal display device. It has been fixed. Specifically, the light guide 20, specifically the guide frame 19 of the light guide 20, is pasted on the back side of the adhesive sheet 22, and the liquid crystal display element 10 having the above-described configuration, specifically polarization is provided on the front side. The lower surface of the plate 7B is disposed and fixed.
[0013]
[Problems to be solved by the invention]
Conventionally, when the point light source 17 is a point light source such as a fluorescent lamp, a band shape is formed in the direction in which the point light source 17 is arranged in the display area of the liquid crystal display element 10 due to the arrangement of the point light sources 17. Illuminance unevenness in which light is dark and dark is generated, and there is a problem that a good display cannot be obtained.
[0014]
The light emitted from the point light source 17 functions as a backlight when passing through the light guide 20. The light from the point light source 17 is, for example, an end face of the light guide. If the inner wall of the casing 24 of the liquid crystal display device facing the white is formed in white, the light reflected on the inner wall can be reflected in the direction of the liquid crystal display element 1 and used again as a backlight. . However, when the flexible wiring board 11 is disposed between the end face of the light guide 20 and the inner wall of the casing 24 of the liquid crystal display device 1, the flexible wiring board 11 is interposed. The reflected light cannot be reused for only the part. For this reason, the light from the point light source 17 cannot sufficiently function as a backlight of the liquid crystal display element 10, and there is a possibility that the display of the liquid crystal display element 10 becomes partially difficult to see.
[0015]
Therefore, in the past, light leakage was prevented by adhering light leakage prevention tape to the end face of the light guide 20, but with such a structure, the step of adhering light leakage prevention tape This increases the production efficiency of the liquid crystal display device and may increase the cost of the liquid crystal display device.
[0016]
The present invention has been made in view of such problems, and by preventing uneven illumination of the point light source, the light from the point light source can function properly as a backlight. An object of the present invention is to provide a liquid crystal display device capable of realizing a good liquid crystal display by preventing leakage.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a liquid crystal display device according to a first aspect of the present invention includes a housing that houses a liquid crystal display element, and emits light of a point light source of a backlight on a power supply side wiring substrate facing the liquid crystal display element. A liquid crystal display in which a light guide having a light guide plate for guiding is mounted , the point light source is disposed on the side of the end face of the light guide plate, and the liquid crystal display element and the light guide are bonded via an adhesive sheet In the apparatus, a covering protrusion is projected on at least one side edge of the adhesive sheet, the covering protrusion is interposed between the inner wall of the casing and the point light source, and at least the back surface of the covering protrusion A diffuse reflection layer is provided in a portion facing the point light source .
A liquid crystal display device according to a second aspect is the liquid crystal display device according to the first aspect, wherein the covering projection edge includes a flexible wiring substrate connected to the liquid crystal display element and a side surface of the light guide. It is arrange | positioned between.
The liquid crystal display device according to claim 3 is the liquid crystal display device according to claim 1 or 2, wherein the light guide includes a guide frame for supporting the light guide plate, and the adhesive sheet is the guide frame. And the liquid crystal display element.
[0018]
And by adopting such a configuration, it is possible to appropriately prevent light from leaking from the end surface of the light guide plate to the outside of the device by disposing a reflective layer facing the end surface of the light guide plate. In addition, the light leakage can be prevented with a simple configuration including the covering protrusion.
[0020]
By adopting such a configuration, the light that has leaked from the end face of the light guide plate is reflected to the liquid crystal display element side by the diffuse reflection layer having a high light reflectance, and can be reused for liquid crystal display. Therefore, it is possible to realize a clearer and better liquid crystal display by concentrating more light on the display area of the liquid crystal display element.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of an adhesive sheet 22 of a liquid crystal display device according to the present invention and a mounting structure using the adhesive sheet 22. Note that the same or corresponding components as those of the conventional one described above will be described with the same reference numerals in the drawings.
[0024]
The adhesive sheet 22 of the present embodiment includes a substantially rectangular frame-like sheet 22A portion that is pasted so as to surround the display area of the liquid crystal display element 10 and the liquid crystal display element 10 and the light guide 20; The frame-shaped sheet portion 22 </ b> A protrudes from one side edge of the frame-shaped sheet portion 22 </ b> A and has a bowl-shaped covering protrusion edge 22 </ b> B that can cover the corresponding end face of the light guide 20.
[0025]
The covering protrusion 22B can be formed on the entire side edge of the frame-shaped sheet portion 22A, but at least as described above, the end face of the light guide 20 and the casing of the liquid crystal display device 1 The flexible wiring board 11 is disposed between the inner wall of the liquid crystal display 24 and the like, so that the light reflected from the inner wall of the casing 24 of the liquid crystal display device is not expected to be reflected and reused. It shall be formed corresponding to the end face of the body 20.
[0026]
In the present embodiment shown in FIG. 1, the covering protrusion 22 </ b> B covers the end surface of the light guide 20 on which the point light source 17 is disposed and the back of the point light source 17. A white diffuse reflection layer 23 is provided at least on the back surface of the point light source 17 on the back surface of 22B.
[0027]
That is, in general, white has a high light reflectivity, so that the light leaking from the end face of the light guide 20 can be favorably reflected to the light guide 20 side by making the diffuse reflection layer 23 white. . The diffuse reflection layer 23 is not limited to the white color described above, and may be, for example, silver matte.
[0028]
By adopting such a configuration, the light that has leaked from the end face of the light guide 20 is reflected to the liquid crystal display element 1 side by the diffuse reflection layer 23 having a high light reflectance, and is again used for liquid crystal display. Since the light from the point light source 17 can be reflected to the light guide 20 side by the diffuse reflection layer 23 and more light can be collected in the light guide 20, the arrangement of the point light sources 17 can be used. Irradiance unevenness appearing as the brightness of the strip-shaped light generated in the direction can be made inconspicuous, and a clear and good liquid crystal display can be realized.
[0029]
Further, in the present embodiment, the width dimension of the portion where the covering protrusion 22 </ b> B is formed is larger than the width dimension of the corresponding end face of the light guide 20. Further, a weakening line 22C made of a perforation is formed at the connecting portion between the frame-shaped sheet portion 22A and the covering edge 22B, and the covering edge 22B portion is bent toward the corresponding end surface of the light guide 20. It is made easy.
[0030]
The end face of the light guide 20 can be properly covered up to both end portions in the longitudinal direction of the width direction by the covering protrusion edge 22B of the adhesive sheet 22 configured in this way. It is possible to prevent the device from coming out of the apparatus.
[0031]
Furthermore, since it is only necessary to form the covering projection edge 22B on the adhesive sheet 22, the number of manufacturing steps can be reduced as compared with the case where the end face of the light guide plate 18 is covered with a light leakage prevention tape.
[0032]
Next, the operation of this embodiment will be described.
[0033]
When the adhesive sheet 22 is mounted on the liquid crystal display device, as shown in FIGS. 1 and 2, the power supply side wiring which faces the liquid crystal display element 10 and has four point light sources 17 arranged on one edge thereof. A light guide 20 having a light guide plate 18 made of a material such as acrylic and a guide frame 19 that supports the light guide plate 18 is mounted on the upper surface of the substrate 16. It arrange | positions so that the said point light source 17 may be located in a side.
[0034]
In the liquid crystal display device shown in FIG. 1, a plurality of prism sheets 21 are disposed on the upper surface of the light guide plate 18, and the light guide 20 is configured together with the light guide plate 18 and the guide frame 19. Yes.
[0035]
And on the upper surface of the said light guide 20, the frame-shaped sheet part 22A formed in frame shape surrounding the display area of the said liquid crystal display element 10 in the said liquid crystal display device, and one side edge of the said frame-shaped sheet part 22A Is provided with an adhesive sheet member 22 including a covering protrusion 22B having a white diffuse reflection layer formed on the back surface thereof, and the liquid crystal display element 10 is provided above the adhesive sheet 22. , Has been fixed. In the mounting, the covering protrusion 22B of the adhesive sheet 22 covers the end surface of the light guide 22 on the side where the point light source 17 is disposed and the back portion of the point light source 17 so as to cover the adhesive sheet 22. Of the liquid crystal display device so as to be positioned on the inner side of the flexible wiring board 11 connecting the liquid crystal terminal 10 and the power supply side wiring board 16, that is, on the light guide 20 side. Mount on the body 24.
[0036]
In the liquid crystal display device configured as described above, the point light source 17 is turned on, and a part of the light emitted from the point light source 17 is directly arranged and another part of the light is arranged on the back part of the point light source 17. The light is reflected by the diffuse reflection layer 23 of the provided adhesive sheet 22 toward the light guide 20 and indirectly incident on the light guide 20.
[0037]
In this way, the light of the point light source 17 is reflected to the light guide 20 side by the diffuse reflection layer 23 of the adhesive sheet 22 disposed on the back of the point light source 17, so that the band-like light generated due to the point light source 17 is generated. Illuminance unevenness in which light brightness is repeated can be alleviated.
[0038]
Incident light from the arrangement side of the point light source 17 proceeds to the opposite side of the point light source 17 while repeating total reflection inside the light guide plate 18 of the light guide 20.
[0039]
The light traveling in the light guide plate 18 is diffused directly or through a diffusion plate (not shown) to the liquid crystal display element 10 located near the upper portion of the light guide 20, thereby the liquid crystal display element. Planar light is irradiated to 10 display areas.
[0040]
At this time, in order to prevent a part of the light traveling in the light guide plate 18 from leaking to the power supply side wiring substrate 16 side without being totally reflected, the light guide 20 on the side of the anti-liquid crystal display element 10 side Is provided with a reflective layer (not shown).
[0041]
As described above, according to the liquid crystal display device having the above-described configuration, the light from the point light source 20 can be appropriately functioned as a backlight, so that a good liquid crystal display can be performed.
[0042]
Further, the number of the covering protrusions 22B is not limited to one as described above. For example, as shown in FIGS. 3 and 4, when two flexible wiring boards 11 that connect the liquid crystal display element 10, the liquid crystal terminal 10, and the power supply side wiring board 16 are provided, An adhesive sheet 22 having the two covering protrusions 22B is formed so as to cover the end face of the light guide 20 on which the flexible wiring board 11 is disposed, and is mounted on the liquid crystal display device.
[0043]
Furthermore, the covering protrusion 22B may be a case where the flexible wiring board 11 is not disposed between the end face of the light guide 20 and the inner wall of the casing 24 of the liquid crystal display device 1. It is optional to form the frame-like sheet portion 22A on the side edge.
[0044]
In this way, the covering protrusion edge 22B of the adhesive sheet is formed, and the covering protrusion edge 22B covers the corresponding end face of the light guide 20 so that light that is about to leak out from the end face is covered with the covering protrusion edge 22B. Since the light can be shielded by the edge 22B, it is possible to prevent light from leaking outside the apparatus.
[0045]
As described above, according to the present embodiment, it is possible to prevent light from leaking from the end face of the light guide plate 18 to the outside of the apparatus by the covering projection edge 22B, so that the light from the point light source 17 is appropriate as a backlight. It can be made to function, and a favorable liquid crystal display can be performed.
[0046]
Moreover, since it is only necessary to form the covering protrusion 22B on the flexible wiring board 11A, it is possible to appropriately prevent light leakage of the backlight while reducing the number of manufacturing steps.
[0047]
Further, by providing a diffuse reflection layer 23 on the back surface of the covering projection edge 22B of the adhesive sheet 22 facing the end surface of the light guide 20, light leaked from the end surface of the light guide 20 is displayed on the liquid crystal display. Therefore, more light can be collected in the display area of the liquid crystal display element 10, whereby a clearer and better liquid crystal display can be performed.
[0048]
In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed. For example, the frame-shaped portion of the adhesive sheet can also have a function as a black mask that covers the non-display area of the liquid crystal display element 10 by forming the surface in black.
[0049]
Moreover, in the said embodiment, although the said light guide 20 was comprised from what is called the light guide plate 18, the guide frame 19, and the prism sheet 21, the essential component of the light guide 20 is only the light guide plate 18. FIG. In addition, it is possible to adopt a configuration in which the engagement convex portion 25 is formed at the edge of the so-called light guide plate 18. In addition, when arrange | positioning the prism sheet 21, the number of sheets is not restricted to 3 sheets of this embodiment, One sheet may be sufficient.
[0050]
【The invention's effect】
As described above, according to the liquid crystal display device according to claim 1 of the present invention, the light leakage of the backlight can be appropriately prevented by the covering protrusion having a simple configuration, and thus the liquid crystal display device is manufactured. A good liquid crystal display can be realized while reducing the number of steps.
[0051]
In addition, according to the liquid crystal display device of the second aspect, the light leaking from the end face of the light guide plate to the flexible wiring board side is favorably reflected to the light guide plate side by forming a diffuse reflection layer having a high reflectance. Therefore, a clearer and better liquid crystal display can be realized by condensing more light on the display area of the liquid crystal display element.
[0052]
Further, according to the liquid crystal display device of the third aspect, by forming the diffuse reflection layer having a high light reflectance, the light leaking from the end face of the light guide plate is reflected to the liquid crystal display element side, and for the liquid crystal display Because it can be reused, more light can be condensed on the display area of the liquid crystal display element to realize a clear and good liquid crystal display, and the light emitted from the point light source can be guided by the diffuse reflection layer. Since it can be reflected to the body side and more light can pass through the light guide, the uneven illumination that appears as the light and darkness of the strip-shaped light generated in the direction in which the point light sources are arranged can be made inconspicuous. A clear and good liquid crystal display can be realized.
[Brief description of the drawings]
1 is an exploded perspective view of a main part of a liquid crystal display device showing an adhesive sheet in a liquid crystal display device according to the present invention. FIG. 2 is a cross-sectional view showing an example of a mounting structure of the adhesive sheet in the liquid crystal display device of the present invention. FIG. 4 is a plan view showing the positional relationship between a liquid crystal display element and a flexible wiring board, with an adhesive sheet having a covering edge formed at a position different from that in FIG. 1. FIG. 4 is a plan view of the adhesive sheet in FIG. FIG. 6 is a longitudinal sectional view showing an example of a liquid crystal display element. FIG. 6 is a sectional view showing an example of a mounting structure of an adhesive sheet in a conventional liquid crystal display device.
DESCRIPTION OF SYMBOLS 10 Liquid crystal display element 11 Flexible wiring board 12 Base film 13 Electric circuit 14 LSI
15 Curved portion 16 Power source side wiring board 17 Point light source 18 Light guide plate 19 Guide frame 20 Light guide 21 Prism sheet 22 Adhesive sheet 22A Frame-like sheet portion 22B Covering edge 22C Weak line 23 Diffuse reflection layer 24 Case

Claims (3)

Comprising a housing for housing the liquid crystal display device, equipped with a liquid crystal display element facing the light guide having a light guide plate for guiding light point source of a backlight to a power source side wiring board, the side of the end face of the light guide plate In the liquid crystal display device in which the point light source is arranged on the side, and the liquid crystal display element and the light guide are bonded via an adhesive sheet, a covering protrusion protrudes from at least one side edge of the adhesive sheet. The covering protrusion is interposed between the inner wall of the housing and the point light source, and a diffuse reflection layer is provided on at least a portion of the back surface of the covering protrusion facing the point light source. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the covering projection edge is disposed between a flexible wiring substrate connected to the liquid crystal display element and a side surface of the light guide.   3. The liquid crystal display device according to claim 1, wherein the light guide includes a guide frame that supports the light guide plate, and the adhesive sheet bonds the guide frame and the liquid crystal display element. .

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