JPH09236800A - Structure of liquid crystal display and planar light source - Google Patents

Abstract

(57) Abstract: A liquid crystal display device is made thin. A liquid crystal display device 1 includes a liquid crystal display panel 3 and a backlight (also referred to as a planar light source, which includes a plate-shaped light guide portion 4c and a lamp 4a for making light incident on the end surface thereof) from the front side, and liquid crystal drive. The circuit boards 5 are housed in the case 2 so as to face each other. The light guide portion 4c has the thickest light incident end face (thickness Wa) and becomes thinner as it goes away from the light incident end face, and the taper portion 4c1 is adjacent to the taper portion and has a minimum thickness (Wb). It is composed of a thin plate portion 4c2 having the same thickness. The front surfaces of the taper portion and the thin plate portion are on the same plane, and the liquid crystal drive circuit board 5 is provided on the back surface side of the thin plate portion.
Is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a liquid crystal display device and a planar light source, and more particularly to reduction in thickness thereof.

[0002]

2. Description of the Related Art The structures of a conventional liquid crystal display device 1 and a planar light source (also called a backlight) 4 will be described with reference to the sectional view of FIG. Case 2 with front cover 2a and rear cover 2b
And a through hole 2a1 is formed inside the front cover 2a excluding its periphery. The liquid crystal display plate 3 is on the front side of the case 2, and the backlight 4 is on the back side of the liquid crystal display plate 3.
Liquid crystal drive circuit boards 5 face the back surface of the backlight 4 and are housed in the case 2.

The liquid crystal display panel 3 has transparent substrates 3a and 3b integrally bonded to each other, various electrodes and the like are formed on the inner surfaces of both substrates, and liquid crystal is sealed between both substrates. The backlight 4 has a plate shape in which a lamp (cold cathode tube or the like) 4a and its reflection plate 4b are attached to the end surface of the light guide portion 4c. The light guide portion 4c is made up of a relatively thick light guide plate 4g made of acrylic, and a thin diffusion sheet 4f and a reflection sheet 4h are laminated on the front and back surfaces of the light guide plate 4g. Converted into light of the shape.

The light of the lamp is incident on the end face of the light guide plate 4g,
Utilizing the difference in the refractive index between acrylic and air, the reflection is repeatedly advanced in the acrylic plate and is reflected by the special ink previously printed on the light guide plate 4g and the reflection sheet 4h,
The light is emitted from the surface of the light guide plate 4g, and further the light is diffused by the diffusion sheet 4f. The liquid crystal drive circuit board 5 is provided with a liquid crystal drive IC 4a made of a polyimide FPC (flexible wiring board).
TCP (Tape Carrier Package) 4c mounted on 4b
Alternatively, various electronic components 4d are mounted. The FPC 4b led out from the liquid crystal drive circuit board 5 is bent in a U-shape and connected to the electrodes around the transparent substrate 3b.

The liquid crystal display panel 3 and the backlight 4 are attached to the front and back surfaces of a common frame portion 6, respectively.

[0006]

Since the liquid crystal display device is thin and lightweight, its use is rapidly expanding as a display portion of a personal computer, word processor or various devices. Recently, however, there has been a strong demand from the user side for further thinning, and whether or not it has come to have a great influence on the market share. The present invention has been made in view of such circumstances.

[0007]

[Means for Solving the Problems]

(1) In the structure of the liquid crystal display device according to claim 1, the light guide portion is
Adjacent to the tapered portion, which is the thickest on the light incident end face side and becomes thinner as it goes away from the incident end face,
It is composed of a thin plate portion having a thickness equal to the minimum thickness of the tapered portion. The taper portion and the front surface of the thin plate portion are flush with each other, and the liquid crystal drive circuit board is arranged on the back surface side of the thin plate portion.

(2) In the invention of claim 2, in the above (1), the maximum value of the thickness of the tapered portion is Wa and the minimum value thereof is Wb.
Then, the thickness Wc including the component mounting height of the liquid crystal drive circuit board is set to Wc≈Wa−Wb. (3) In the invention of claim 3, in the above (1), the liquid crystal display plate and the backlight are attached to a common frame portion.

(4) In the structure of the planar light source according to claim 4, the light guide portion is adjacent to the tapered portion and the tapered portion which is thickest on the light incident end face side and becomes thinner as it goes away from the incident end face. It is composed of a thin plate portion having a thickness equal to the minimum thickness of the tapered portion.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to examples in FIGS. However, in these figures, parts corresponding to those in FIG. According to the present invention, in order to reduce the thickness of the device, the light guide portion 4c is thicker on the light incident end face side as in the conventional case (the thickness thereof is Wa), but becomes thinner as the distance from the incident end face becomes smaller. And adjacent to the tapered part,
Thin plate portion 4 having a thickness equal to the minimum thickness Wb of the tapered portion
and c2. The front surfaces (the surfaces facing the liquid crystal display plate 3) of the tapered portion 4c1 and the thin plate portion 4c2 are flush with each other. That is, they are on the same plane. Then, the liquid crystal drive circuit board 5 is arranged on the back surface side of the thin plate portion 4c2.

In the light guide portion 4c, a thin front diffusion sheet 4 is used.
Although the thickness of f and the reflection sheet 4h on the back surface is constant, the thickness of the light guide plate 4g, which occupies most of the thickness, changes. In the light guide portion 4c, the surface density is changed by changing the print density of the ink to be printed on the light guide plate 4g according to the attenuation rate of the light that changes corresponding to the distance from the light source and the thickness of the light guide plate. As a light source, it has the same illuminance uniformity as before.

The thickness Wc including the component mounting height of the liquid crystal drive circuit board 5 is, as can be seen from FIG. 1, the taper portion 4c1.
The respective thicknesses are set so as to be substantially equal to the difference between the maximum value Wa and the minimum value Wb (equal to the thickness of the thin plate portion 4c2). The liquid crystal display panel 3 and the backlight 4 are attached to the front and back surfaces of a common frame 6 as in the conventional case, and the device 1 is thin and compact as a whole.

[0013]

As described above, according to the present invention, the thickness decreases from Wa to Wb as the light guide portion 4c of the backlight is separated from the lamp side. Tapered portion 4c1 and thin plate portion 4c having a thickness equal to the minimum thickness Wb of the tapered portion
2 and the liquid crystal drive circuit board 5 is disposed on the back surface side of the thin plate portion 4c2, the thickness of the liquid crystal display device 1 can be reduced by the dimension Wa-Wb in which the thin plate portion 4c2 is thinner than before. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a light guide section 4c of FIG.

FIG. 3 is a cross-sectional view of a conventional liquid crystal display device.

Claims (4)

[Claims] 1. A liquid crystal display panel, a backlight (having a plate-shaped light guide section and a lamp for making light incident on the end surface of the light guide section), and a liquid crystal drive circuit board face each other in this order from the front side of the device. Then, in the structure of the liquid crystal display device housed in the case, the light guide portion is thickest on the incident end face side of light, and a taper portion that becomes thinner as it goes away from the incident end face, and adjacent to the taper portion, The thin plate portion has a thickness equal to the minimum thickness of the tapered portion, the front surfaces of the tapered portion and the thin plate portion are flush with each other, and the liquid crystal drive circuit board is arranged on the back surface side of the thin plate portion. The structure of the liquid crystal display device characterized in that 2. The thickness Wc including the component mounting height of the liquid crystal drive circuit board is Wc≈Wa−, where Wa is a maximum value and Wb is a minimum value of the thickness of the tapered portion. A structure of a liquid crystal display device characterized by being set to Wb. 3. The structure of a liquid crystal display device according to claim 1, wherein the liquid crystal display panel and the backlight are attached to a common frame portion. 4. A structure of a planar light source, wherein light of a lamp is condensed on an end surface of a light guide section by a reflector, and the light incident on the end surface of the light guide section is converted into a planar light having uniform illuminance. The light guide portion has a taper portion that is thickest on the light incident end face side and becomes thinner as it goes away from the light incident end face, and a thin plate portion adjacent to the taper portion and having a thickness equal to the minimum thickness of the taper portion. A structure of a planar light source, comprising: