JP4115867B2 - Planar light source device and liquid crystal display device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct-type planar light source device in which a light source is disposed directly under a liquid crystal display panel, and a liquid crystal display device using the device.
[0002]
[Prior art]
A conventional liquid crystal display device includes a liquid crystal panel that displays an image. The cross-sectional shape is L-shaped, and a frame that covers and supports the side portion of the surface of the liquid crystal panel and constitutes the entire side portion of the liquid crystal display device is provided. Further, the liquid crystal panel is provided with a connection substrate for driving the liquid crystal panel. The liquid crystal panel and the connection substrate are bent at a substantially right angle, and the connection substrate is housed inside the frame (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2002-31418A (page 4, right column, line 9-page 5, left column, line 37, FIG. 2)
[0004]
[Problems to be solved by the invention]
A conventional liquid crystal display device is a flat-type display device having a relatively small thickness. However, when the liquid crystal display panel is enlarged, for example, when opposite rotational forces are applied to both sides on one diagonal line, for example. There is a problem that the strength against twisting is extremely small.
[0005]
In addition, since the strength against deformation such as bending and distortion of the frame is small, the liquid crystal display panel covered with the frame is easily twisted, and the gap between the two transparent insulating substrates corresponding to the thickness of the liquid crystal layer of the liquid crystal display panel. Changes, which has a problem of adversely affecting the display.
[0006]
The present invention has been made to solve the above-described problems, and provides a planar light source device that suppresses twisting of a frame even when a liquid crystal display panel is enlarged. It is an object of the present invention to provide a liquid crystal display device that can maintain a constant thickness of a liquid crystal layer of a liquid crystal display panel and obtain excellent display characteristics by using the device.
[0007]
[Means for Solving the Problems]
In the planar light source device according to the present invention, the bottom surface of the first frame is disposed at a position facing the diffusion plate with respect to the linear light source, and the first frame extends in the longitudinal direction of the linear light source. A planar light source device having side surfaces on both sides inclined outward with respect to the bottom surface of the first frame, and the first frame having end surfaces bent from the side surfaces of the first frame, A fixing means for connecting at least one end surface portion of one frame and the bottom surface portion of the first frame is provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
1 is an exploded perspective view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a partial sectional view of the liquid crystal display device shown in FIG. 1 and 2, the liquid crystal display device 1 includes a metal front frame 2, a direct-type planar light source device 3, and a rectangular flat plate shape held between the front frame 2 and the planar light source device 3. It consists of a liquid crystal display panel 4 and the like. Hereinafter, for the sake of explanation, the display surface side of the liquid crystal display device 1 is referred to as the upper side.
[0009]
The front frame 2 has a rectangular opening 2a that substantially corresponds to the display area of the liquid crystal display panel 4, a rectangular ring-shaped horizontal portion 2b that surrounds the opening 2a from four sides, and the entire outer periphery of the horizontal portion 2b. And a vertical portion 2c extending downward.
[0010]
The liquid crystal display panel 4 is a TFT in which a colored layer, a light shielding layer, a thin film transistor (hereinafter referred to as TFT) serving as a switching element, an electrode such as a pixel electrode, and a wiring are formed on an upper or lower transparent insulating substrate (not shown). Array substrate and counter substrate, spacers for holding two substrates at equal intervals, sealing material for bonding two substrates, sealing material for sealing after injecting liquid crystal between two substrates, and liquid crystal Although it is composed of an alignment film having an initial alignment and a polarizing plate for polarizing light, etc., in the present invention, since an existing liquid crystal display panel is used, description thereof is omitted here.
[0011]
The planar light source device 3 includes a cold cathode tube, which is a plurality of linear light sources 5 arranged in parallel to each other in parallel to the display surface, a pair of support bases 6 that collectively support the plurality of linear light sources 5, and the support. A metal rear frame (hereinafter referred to as the first frame 7) combined from below the base 6 and a diffusion plate 8 disposed above the support base 6 are included. The frame structure of the planar light source device 3 includes a support frame 6, a first frame 7, and a mold frame made of resin such as polycarbonate (PC) having a rectangular opening 9a (hereinafter referred to as a second frame 9). ). The diffusion plate 8 is sandwiched between the first frame 4 and the second frame 9.
[0012]
The diffusion plate 8 diffuses light emitted from the linear light source 5. The diffusion plate 8 is made of acrylic, polyethylene terephthalate (PET), polycarbonate (PC), or the like, which is a resin mixed with a light scattering material. In addition, the diffusion plate 8 covers the opening 9a of the second frame 9 in order to spread light directly emitted from the linear light source 5 and light reflected by a reflection plate, which will be described later, uniformly in the display surface. And has a function of uniformly radiating light incident in an oblique direction in all directions on the surface.
[0013]
An optical sheet (not shown) composed of a plurality of optical sheets for effectively using light is disposed on the diffusion plate 8, and the liquid crystal display panel 4 is disposed on the diffusion plate 8 via the optical sheets. In addition, when it is necessary to improve the luminance of the optical sheets, a plurality of lens sheets are combined in consideration of the direction of the prism formed on the surface thereof. In addition, two or more diffusion sheets can be used when improving the diffusibility. Further, depending on the light distribution characteristics of the prism sheet, one or no prism sheet may be used. In addition, a protective sheet, a prism sheet, or a polarizing reflection sheet may be combined or not used.
[0014]
The first frame 7 includes the linear light source 5 and has a function of reflecting light emitted from the linear light source 5 toward the diffusion plate 8. As a function of reflecting, for example, a reflecting plate that reflects light with regular reflection, diffuse reflection, or a combination thereof is formed on the bottom surface and side surface that are the inside of the first frame 7. As a material of the reflecting plate, a metal plate or a laminated plastic sheet such as aluminum or silver which is easy to reflect, or a material such as a foamed plastic sheet, a metal or plastic coated with a reflective material may be applied. In particular, it is preferable to apply a white paint or the like to the inside of the first frame 7 because the internal reflection is further improved and the loss of light is reduced.
[0015]
The bottom surface portion 7 a of the first frame 7 is disposed at a position facing the diffusion plate 8 with respect to the linear light source 5. As clearly shown in FIG. 2, the side surface portions 7b on both sides of the first frame 7 extending in the longitudinal direction of the linear light source 5 are inclined outwardly with respect to the bottom surface portion 7a and bent from the side surface portion 7b. The first frame 7 has an end surface portion 7c provided. In this embodiment, the first frame 7 is made of a highly rigid metal member such as aluminum, stainless steel, or iron.
[0016]
The end surface portion 7 c of the first frame 7 has a comb-tooth shape in which a plurality of convex portions 10 a and concave portions 10 b are formed along the longitudinal direction of the first frame 7. Note that the position of the recess 10b in the longitudinal direction of the first frame 7 corresponds to the position of a tape carrier package (hereinafter referred to as TCP 12) that connects the liquid crystal display panel 4 and the drive circuit board 11, thereby providing a liquid crystal display. The TCP 12 can be folded back so that the drive circuit board 11 is disposed on the back side of the panel 4, and the frame of the liquid crystal display device 1 can be reduced, which is preferable.
[0017]
A plurality of TCPs 12 are connected to the peripheral edge of the liquid crystal display panel 4. The drive circuit board 11 for supplying a drive input signal to the TCP 12 can be screwed to the side surface portion 7 b of the first frame 7, for example.
[0018]
The fixing means 13 is made of a highly rigid metal member such as aluminum, stainless steel, or iron that connects the bottom surface portion 7a and the end surface portion 7c of the first frame 7. The fixing means 13 includes a main surface portion 13a having a length substantially equal to the length in the longitudinal direction of the side surface portion 7c of the first frame 7, and a bent portion bent along a folding line 13b extending in the longitudinal direction from the main surface portion 13a. Part 13c. In this example, the bent portion 13c is bent substantially perpendicularly to the main surface portion 13a. As shown in FIG. 2, the outer surface of the bent portion 13c comes into contact with the inner surface of the vertical portion 2c of the front frame 2 as shown in FIG. Yes. In addition, the bent portion 13 c of the fixing means 13 has a comb-teeth shape in which convex portions 14 a and concave portions 14 b are formed so as to mesh with the comb teeth of the end surface portion 7 c of the first frame 7.
[0019]
In this embodiment, the convex portions 14 a and the concave portions 14 b formed on the bent portion 13 c of the fixing means 13 are engaged with the convex portions 10 a and the concave portions 10 b formed on the end surface portion 7 c of the first frame 7. Thereafter, the screw as the screwing means 15 is rotated and press-fitted into the screw receiving portion provided in the bottom surface portion 7a of the first frame 7 through the insertion hole provided in the main surface portion 13a of the fixing means 13. Thus, the fixing means 13 is fixed to the first frame 7.
In this embodiment, the main surface portion 13a of the fixing means 13 is fixed to the bottom surface portion 7a of the first frame 7 by the screw which is the screwing means 15, but the bottom surface portion of the first frame 7 is fixed. 7a may be fixed, and the main surface portion 13a of the fixing means 13 may be fixed by a claw that forms a hole that fits into the protrusion. It may also be fixed by caulking.
[0020]
In this embodiment, the end face portion 7c of the first frame 7 and the bent portion 13c of the fixing means 13 are engaged in a comb-teeth shape so that the assembling work for fixing the fixing means 13 to the first frame is performed. Preferably, the fixing means 13 is provided with an insertion hole in the bent portion 13c of the fixing means 13 and a screw receiving portion in the end face part 7c of the first frame 7, and the fixing means 13 is rotated and press-fitted with a screw as a screwing means. May be fixed to the first frame 7.
[0021]
Further, the fixing means 13 is fixed to the first frame 7 only on the side where the driving circuit board 11 is connected to the liquid crystal display panel 4 among the end surface portions 7c on both sides of the first frame 7, By fixing the fixing means 13 to the first frame 7 also on the side where the drive circuit board 11 is not connected to the display panel 4, it is possible to further increase the strength against deformation such as twisting.
[0022]
Further, although a cold cathode tube is used as the linear light source 5, a light source in which a plurality of point light sources such as light emitting diodes are arranged along the longitudinal direction of the first frame 7 if sufficient luminance can be obtained. It may be used.
[0023]
Further, as the liquid crystal display panel 4, a voltage is applied to the pixel electrode and the counter electrode on the first insulating substrate, the second insulating substrate facing the first insulating substrate, and the pixel electrode and the counter electrode. Thus, an existing lateral electric field method (hereinafter referred to as IPS method) including a liquid crystal layer including liquid crystal molecules driven by an electric field generated substantially parallel to the surface of the first insulating substrate. A liquid crystal display panel may be used.
[0024]
As described above, by connecting the main surface portion 13a and the bent portion 13c of the fixing means 13 to the side surface portion 7b and the end surface portion 7c of the first frame 7 configured by a plane having low strength against deformation such as torsion, By constructing an annular solid body on the side surface in the longitudinal direction of the first frame 7, it is possible to increase the strength against deformation such as twisting of the first frame 7. Thereby, it is possible to obtain the planar light source device 1 in which the twist of the frame is suppressed. In particular, in the IPS liquid crystal display panel 4 that requires strict control of the gap between the array substrate and the counter substrate, the thickness of the liquid crystal layer can be kept constant and excellent display characteristics can be obtained.
[0025]
【The invention's effect】
As described above, according to the present invention, the bottom surface portion of the first frame is disposed at a position facing the diffusion plate with respect to the linear light source, and is formed on both sides of the first frame extending in the longitudinal direction of the linear light source. A planar light source device having a side surface portion inclined outward with respect to a bottom surface portion of a first frame, and the first frame having an end surface portion bent from the side surface portion of the first frame. By providing a fixing means for connecting at least one end surface portion of the frame and the bottom surface portion of the first frame, the frame can be formed without increasing the thickness of the frame or changing the frame to a member having high rigidity. It becomes possible to suppress the twist of the.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.
2 is a partial cross-sectional view of the liquid crystal display device shown in FIG. 1 as viewed from the line II-II.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal display device, 3 Planar light source device, 4 Liquid crystal display panel, 5 Linear light source, 7 First frame, 7a Bottom surface part, 7b Side surface part, 7c End surface part, 8 Diffusion plate, 9 Second frame, 10a Convex part, 10b Concave part, 11 Drive circuit board, 13 Fixing means, 13a Main surface part, 13b Bending part, 13c Bending part, 14a Convex part, 14b Concave part, 15 Screwing means

Claims (8)

A plurality of linear light sources arranged side by side;
A diffusion plate for diffusing light emitted from the linear light source;
A first frame including the linear light source and having a function of reflecting light emitted from the linear light source toward the diffusion plate;
A second frame sandwiching the diffuser plate with the first frame;
The bottom surface of the first frame is disposed at a position facing the diffuser with respect to the linear light source,
Side surfaces on both sides of the first frame extending in the longitudinal direction of the linear light source are inclined outward with respect to the bottom surface of the first frame;
The planar light source device, wherein the first frame has an end surface portion bent from a side surface portion of the first frame,
A planar light source device comprising a fixing means for connecting at least one end surface portion of the first frame and a bottom surface portion of the first frame. 2. The planar light source device according to claim 1, wherein the fixing means and the first frame are metal members. 3. The planar light source device according to claim 1, wherein the end surface portion and the side surface portion of the first frame and the fixing means are connected to form an annular shape. 4. The fixing means has a main surface portion having a length substantially equal to the length in the longitudinal direction of the side surface portion of the first frame, and a bent portion bent along a folding line extending in the longitudinal direction from the main surface portion. 4. The planar light source device according to claim 1, wherein the planar light source device is a member. The end face of the first frame has a comb-like shape with irregularities formed along the outer edge in the longitudinal direction, and the bent part of the fixing means forms irregularities that mesh with the comb teeth of the end face of the first frame. The planar light source device according to claim 4, wherein the end surface portion of the first frame and the bent portion of the fixing means are held by the comb-tooth shape. 6. The planar light source device according to claim 5, wherein a main surface portion of the fixing means and a bottom surface portion of the first frame are fixed by screwing means. A planar light source device according to any one of claims 1 to 6, a liquid crystal display panel comprising two transparent insulating substrates disposed above the planar light source device and sandwiching liquid crystal, and connected to the liquid crystal display panel A liquid crystal display device comprising a driving circuit board. The liquid crystal display panel includes a first transparent insulating substrate having a pixel electrode and a counter electrode, a second transparent insulating substrate facing the first transparent insulating substrate, and the pixel electrode and the counter electrode. 2. A liquid crystal layer comprising liquid crystal molecules driven by an electric field generated substantially parallel to the surface of the first transparent insulating substrate by applying a voltage to the electrodes. 8. A liquid crystal display device according to 7.

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