JPH0659262A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the number of parts by using a resin molding member having a high reflectivity as a rear surface cover and further, covering the rear surface of a light transmission plate with a rear surface cover having a high reflectivity, thereby constituting the reflection member of a back light in common use as the rear surface cover. CONSTITUTION:A light transmissive acrylic plate, etc., are used for the light transmission plate 13 and a diffusion sheet 17 for diffusing forward exit light toward a liquid crystal display plate 12 is disposed in parallel on the front surface thereof. The rear surface of the light transmission plate 13 is covered with the rear surface cover 15 and the end face exclusive of a light source 14 of the light transmission plate 13 is covered with the rear surface cover 15. The resin molding member having the high reflectivity is use for this rear surface cover 15. The rear surface cover 15 has a rear surface reflection surface 21 disposed on the rear surface of the light transmission plate 13, an end face reflection surface 22 disposed on the end face exclusive of the light source 14 side of the light transmission plate 13 and a light source reflection surface 23 disposed on the circumference of the light source 14 exclusive of the light transmission plate 13. All the reflection members of the back light of this constitution are commonly formed by the rear surface cover 15 in such a manner and, therefore, many reflection plates, reflection sheets, etc., are omitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device with a backlight used as a display device for word processors, personal computers and the like.

[0002]

2. Description of the Related Art Generally, as shown in FIGS. 3 and 4, a rear illumination device (backlight) 3 is disposed on the rear surface side of a liquid crystal display panel (LCD panel) 2 having a drive circuit 1. The structure and principle of the back lighting device 3 are as follows.

A light source 5 is arranged in the vicinity of one end surface of the transparent light guide plate 4.

A reflection sheet 6 is provided on the side opposite to the light guide plate 4 of the light source 5, and the light emitted from the light source 5 is reflected directly and by the reflection sheet 6 and is incident on the end face of the light guide plate 4. It

The light entering the light guide plate 4 is a dot pattern (not shown) provided on the rear surface of the light guide plate 4 by printing or the like.
While advancing, the light proceeds to the inner side (side surface side) of the light guide plate 4.

The diffused light is reflected upward by the reflection plate 7 provided on the rear surface of the light guide plate 4, passes through the diffusion sheet 2a, and illuminates the liquid crystal display plate 2 from the rear surface. Further, the light reaching from the light source 5 to the opposite side end surface of the light guide plate 4 is reflected by the reflection sheet 8 attached to each end surface with an adhesive material or the like and is reused, which contributes to the improvement of brightness.

A liquid crystal display panel LCD panel is superposed on the front side of the back lighting device 3 and is sandwiched by a front metal frame 9 and a rear holding member 10.

[0008]

However, in the back lighting device 3 having this structure, the reflecting plate 7 and the reflecting sheets 6 and 8 are provided.
Since a large number of parts such as the above are used, the assembly of the liquid crystal display device with a back light becomes complicated and there is a problem that it leads to an increase in cost.

In view of the above problems, it is an object of the present invention to provide a liquid crystal display device capable of reducing the number of parts.

[0010]

As shown in FIGS. 1 and 2, a liquid crystal display plate 12 and a light-transmissive light guide plate arranged behind the liquid crystal display plate 12 are provided. Thirteen
A light source 14 close to at least one end surface of the light guide plate 13 and a rear surface cover 15 for holding these from behind.
A liquid crystal display device with a backlight, comprising: a metal frame body 16 that is held in a frame shape from the front surface;
Is a resin molded member having high reflectance, and the rear surface of the light guide plate 13 is covered with the rear cover 15.

According to a second aspect of the present invention, a liquid crystal display plate 12, a light-transmitting light guide plate 13 arranged behind the liquid crystal display plate 12, and at least one end surface of the light guide plate 13 are provided close to each other. Light source 14, a rear cover 15 for holding these from the rear, and a metal frame body 16 for holding the light source 14 in a frame shape from the front.
In the liquid crystal display device with a backlight having, the rear cover 15 is made of a resin molded member having a high reflectance, and the end surface of the light guide plate 13 except the light source 14 side is covered with the rear cover 15. It is a thing.

According to a third aspect of the present invention, a liquid crystal display plate 12, a light-transmitting light guide plate 13 disposed behind the liquid crystal display plate 12, and at least one end surface of the light guide plate 13 are provided in proximity to each other. Light source 14, a rear cover 15 for holding these from the rear, and a metal frame body 16 for holding the light source 14 in a frame shape from the front.
In a liquid crystal display device with a backlight having the following, the rear cover 15 is made of a resin molded member having a high reflectance, and the periphery of the light source 14 excluding the light guide plate 13 is covered with the rear cover 15. Is.

According to a fourth aspect of the present invention, in the resin molding member having high reflectance according to any one of claims 1 to 3, a polycarbonate resin containing at least 5 to 20 wt% of titanium dioxide is used, and the reflectance is A liquid crystal display device characterized by being set to 70% or more.

[0014]

In the means for solving the problems according to claims 1 to 4, the rear cover 15 also serves as the reflecting member of the backlight.
The conventional reflection plate and reflection sheet are omitted.

[0015]

1 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention in one direction, and FIG. 2 is a cross-sectional view of the liquid crystal display device according to an embodiment of the present invention in another direction.

As shown in the figure, the liquid crystal display device of this embodiment is
Liquid crystal display panel 12 (LCD panel) having drive circuit 11
A transparent light guide plate 13 arranged in parallel behind the liquid crystal display plate 12, a light source 14 close to one end surface of the light guide plate 13, and a rear cover 15 (plastic (Chassis) and a metal frame body 16 (metal bezel) which holds the front surface in a frame shape.

The drive circuit 11 is a general circuit similar to the conventional one, which supplies a drive signal to the electrodes of the liquid crystal display plate 12, and together with the liquid crystal display plate 12, the rear cover 15 is provided.
And is sandwiched between the metal frame bodies 16.

The light guide plate 13 is made of a translucent acrylic plate or the like having a thickness of about 2 mm, and a diffusion sheet 17 for diffusing the outgoing light toward the front is directed to the liquid crystal display plate 12 on the front surface thereof.
Are arranged in parallel. The rear surface of the light guide plate 13 is covered with the rear surface cover 15. The end surface of the light guide plate 13 except the light source 14 side is covered with the rear surface cover 15.

The light source 14 is a cold cathode fluorescent lamp (CCFT) having a tube diameter of about 3 mm, and is arranged near one end surface of the light guide plate 13. The periphery of the light source 14 excluding the light guide plate 13 is covered with the rear cover 15.

The rear cover 15 is a resin molded member having a high reflectance, and is made of a polycarbonate resin containing at least 5 to 20 wt% of titanium dioxide, which is a white pigment, and the reflectance thereof is set to 70% or more. . That is, the resin that is the base of the resin molded member with high reflectance is
A polycarbonate resin was selected in consideration of flame retardancy, moldability, etc., and in order to obtain a resin having high reflectance, a method of containing titanium dioxide, which is an excellent white pigment, was adopted. As a result of examining the reflectance and the formability of the blending ratio, Table 1
When the compounding ratio is less than 5%, the reflectance is about 70%.
Since the reflectance is less than the above value, it is not possible to sufficiently obtain the brightness which is one of the optical characteristics of the liquid crystal display device. further,
If the compounding ratio exceeds 20%, the viscosity becomes high and the moldability becomes poor. In this embodiment, the rear cover 15 is molded by a molding method such as injection molding using polycarbonate containing about 10 wt% of titanium dioxide.

[0021]

[Table 1]

The rear cover 15 has a rear reflecting surface 21 arranged on the rear surface of the light guide plate 13, an end reflecting surface 22 arranged on the end surface of the light guide plate 13 excluding the light source 14 side, and the light guide plate 13 of the light source 14. Except that the light source reflection surface 23 is provided in the surroundings.

The metal frame 16 has a display window 2 corresponding to a liquid crystal effective display area of the liquid crystal display plate 12 at the front center portion.
5 is formed.

At the time of assembling the liquid crystal display device having the above structure, first, the light guide plate 13 and the light source 14 are arranged in front of the rear cover 15.

Next, the diffusion sheet 17 is arranged in front of it, and the liquid crystal display plate 12 having the drive circuit 11 is further stacked.

Then, a metal frame 16 is covered from the front thereof, and a liquid crystal display plate 12 having a light guide plate 13, a light source 14, a diffusion sheet 17 and a driving circuit 11 is sandwiched and held, and an integrated liquid crystal display with a backlight is provided. The device.

In the liquid crystal display device thus assembled,
Since the rear cover 15 also serves as the reflecting member of the backlight, a large number of reflecting plates and reflecting sheets can be omitted as in the conventional case, and the assembly of the liquid crystal display device becomes easy.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in the above embodiment, all the requirements of claims 1 to 3 are satisfied at the same time, but, for example, each claim 1 to 3 may be incorporated independently.

That is, when claim 1 is used alone, only the rear surface of the light guide plate 13 may be covered with the rear cover 15. In this case, a reflection sheet may be attached to the end surface of the light guide plate 13 other than the light source 14 side, and a thin reflection sheet may be used as the reflection means around the light source 14.

When the second aspect is used alone, only the end portion of the light guide plate 13 except the light source 14 side may be covered with the rear cover 15. In this case, in order to reduce the weight as much as possible, the rear surface of the light guide plate may be once exposed by hollowing out the central portion of the rear cover 15, and a thin reflection sheet may be arranged on the rear surface of the light guide plate 13. A thin reflection sheet may be used as the reflection means around the light source 14.

Furthermore, when the third aspect is used alone, only the periphery of the light source 14 excluding the light guide plate 13 may be covered with the rear cover 15. In this case, a thin reflection sheet may be arranged on the rear surface of the light guide plate 13, and the reflection sheet may be attached to the end surface of the light guide plate 13 other than the light source 14 side.

Besides, any two claims may be combined.

[0034]

As is apparent from the above description, according to claims 1 to 4 of the present invention, a resin molded member having a high reflectance is used as the rear surface cover, and in claim 1, the rear surface of the light guide plate is defined as follows. Since the end face of the light guide plate excluding the light source side is covered with the rear cover having a high reflectance in the third aspect, the periphery of the light source except the light guide plate is covered by the rear cover. Therefore, the reflector and the reflection sheet can be omitted as compared with the conventional example. Therefore, there is an excellent effect that the liquid crystal display device is easily assembled.

[Brief description of drawings]

FIG. 1 is a unidirectional sectional view showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view in another direction showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional liquid crystal display device.

FIG. 4 is a plan view showing a back lighting device of a conventional liquid crystal display device.

[Explanation of symbols]

 11 Drive Circuit 12 Liquid Crystal Display Plate 13 Light Guide Plate 14 Light Source 15 Rear Cover 16 Metal Frame

Claims (4)

[Claims] 1. A liquid crystal display plate, a translucent light guide plate arranged behind the liquid crystal display plate, a light source close to at least one end face of the light guide plate, and a rear cover for holding these from the rear. In the liquid crystal display device with a backlight having a metal frame body that holds the frame shape from the front surface, the rear surface cover is made of a resin molded member having a high reflectance, and the rear surface of the light guide plate is the rear surface cover. A liquid crystal display device characterized by being coated with. 2. A liquid crystal display plate, a translucent light guide plate arranged behind the liquid crystal display plate, a light source close to at least one end face of the light guide plate, and a rear cover for holding these from the rear side. In a liquid crystal display device with a backlight having a metal frame body that is held in a frame shape from the front surface, the rear surface cover is made of a resin molding member having a high reflectance, and the end surface of the light guide plate excluding the light source side is A liquid crystal display device characterized by being covered with the rear cover. 3. A liquid crystal display plate, a translucent light guide plate arranged behind the liquid crystal display plate, a light source close to at least one end face of the light guide plate, and a rear cover for holding these from the rear. And a liquid crystal display device with a backlight having a metal frame body which is held in a frame shape from the front surface, the rear surface cover is made of a resin molded member having a high reflectance, and the periphery except the light guide plate of the light source is A liquid crystal display device, which is covered with a rear cover. 4. The resin molded member having a high reflectance according to claim 1, wherein a polycarbonate resin containing at least 5 to 20 wt% of titanium dioxide is used, and the reflectance is set to 70% or more. Characteristic liquid crystal display device.