JPH04172319A - Liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain a thin liquid crystal display without contrast nonuniformity on screen by bleuding glass whose heat conduction rate is high in a diffusion plate so as to eliminate the temperature distribution nonuniformity on the surface of a-liquid crystal display element caused by thickness reduction of the liquid crystal display. CONSTITUTION:Glass ingredients are contained in the diffusion plate 6 of a back light unit 4, which constitutes the liquid crystal display in the title. Since, for this reason, the glass ingredients have a higher heat conduction rate than that of acrylic or polycarbonate, which is a component of an ordinary diffusion plate, the heat generated from an FL tube (cold cathode tube) 8 is quickly and uniformly diffused on the surface of the diffusion plate 6. Therefore, the nonuniformity of heat radiation of the diffusion plate 6 becomes less, eventually, the temperature distribution nonuniformity on a liquid crystal element 1 can be suppressed. The contrast nonuniformity of a liquid crystal display screen along with this nonuniformity is also hardly generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device having a backlight unit used in portable electronic devices such as portable personal computers and word processors.

[Conventional technology]

As an example of conventional technology, FL (
A liquid crystal display device having a bank light unit (cold cathode tube) will be described.

As shown in FIG. 1, the FL bank light unit used for this purpose has a structure in which the following parts are stacked in this order: a diffusion plate 6, a diffusion sheet 7, and an FL tube 8, and the side and bottom surfaces of these parts are covered with a lamp housing 9. It becomes. This arrangement remains unchanged in the present invention.

The material of this diffuser plate is acrylic, heat-resistant resin, polycarbonate, etc., and the distance between the diffuser plate and the FL tube is generally about 2.0 to 2.5 mm. With this structure, an FL bank light unit is realized that enables uniform surface light emission using the FL tube as a light source.

[Problem to be solved by the invention]

With the recent trend toward downsizing of electronic devices, backlight units for illumination are also required to be thinner.

In order to meet this demand, it is necessary to reduce the total thickness, that is, to reduce the diameter of the FL tube and to reduce the distance between the diffuser plate and the FL tube. However, if we simply try to satisfy this condition without changing the brightness, the heat generated from the FL tube will increase and the distance between it and the diffuser plate will become smaller, causing the heat to be emitted on the FL backlight unit surface. Heat distribution becomes uneven.

As a result of this, the heat absorbed by the liquid crystal element surface on the top surface of the FL bank light unit becomes uneven, which causes uneven temperature distribution on the element surface, and further causes changes in the contrast of the liquid crystal display screen. .

It is an object of the present invention to solve the above-mentioned problems and to realize a liquid crystal display device with no contrast unevenness on the liquid crystal screen even when the device is made thinner.

[Means to solve the problem]

In order to achieve the above object, the means adopted by the present invention is that a glass component is contained in the diffuser plate of the Buffkrite unit constituting the liquid crystal display device.

C effect] When the diffuser plate contains a glass component as in the present invention,
The glass component has higher thermal conductivity than acrylic, polycarbonate, etc., which are the components of conventional diffuser plates. For this reason, F
The heat generated from the L tube quickly and uniformly diffuses to the surface of the diffuser plate. Therefore, unevenness in heat dissipation on the surface of the diffuser plate is reduced, and as a result, unevenness in temperature distribution of the liquid crystal element can be suppressed.

Therefore, unevenness in the contrast of the liquid crystal display screen due to this unevenness does not occur.

Table 1 is a list of thermal conductivity by material. It can be seen from this table that the thermal conductivity of glass is higher than that of other conventional materials.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows the liquid crystal display device of the present invention! FIG. 2 is an exploded perspective view of an embodiment for explaining the present invention.

Liquid crystal display devices are roughly divided into two types: liquid crystal display element l;
A liquid crystal display consisting of a printed circuit board 3 connected to the liquid crystal display element l via a flexible substrate 2;
There are two bank light units 4. Figure 2 shows a completed diagram of this.

In FIG. 2, the FL bank light unit 4 consists of a diffusion plate 6, a diffusion sheet 7, an FL tube 8, and a lamp housing 9 in order from the top, and a printed circuit board is connected to the top via a flexible board 2. A liquid crystal display element 1 is installed.

Next, the function of the FL backlight unit of the liquid crystal display device will be explained based on FIG.

FL bank light unit 4, which is part of the liquid crystal display device
The light emitted from the FL tube is reflected to the upper surface by the lamp housing 9 and uniformly diffused by the diffusion sheet 7 and the diffusion plate 6 to form a surface light source, and this arrangement itself is well known.

The feature of the present invention lies in the material of the diffusion plate 6, as shown in FIG. 4, in that a conventional diffusion plate made of resin such as acrylic and mixed with glass particles is used. Fourth
The figure shows the glass bodies 10 being dispersed in a diffusion plate material such as acrylic, heat-resistant resin, or polycarbonate. Although the glass component 10 is shown in the form of fine particles in this example, it may also be in the form of fibers.

Since glass has a higher thermal conductivity than acrylic, a diffusion plate containing glass has a higher thermal diffusion rate than a conventional diffusion plate without glass.

Therefore, even if the distance between the diffuser plate and the FL tube is shortened and the diameter of the FL tube is reduced in response to the request for a thinner overall thickness of the bank light, the heat diffusion of the diffuser plate is faster. ,
Local heating of the liquid crystal display element due to heat generation of the FL tube can be prevented. Therefore, there is an effect that uneven temperature distribution of the liquid crystal display element does not occur and uneven contrast of the screen is eliminated.

However, since glass has higher light transmittance than acrylic resin, an acrylic resin with lower transmittance than conventional ones should be used to prevent the light transmittance of the diffuser plate from becoming excessively high.

FIG. 3 shows a conventional diffusion plate made of acrylic, heat-resistant resin, polycarbonate, etc. The slope shown here represents the transmittance of this diffuser plate by its linear density. The diagonal line in Figure 4 also indicates the transmittance, but this is the transmittance of the plate material before the glass is dispersed, and the third
Since the transmittance is lower than in the figure, the linear density is shown to be low.

By mixing a glass component with this, the light transmittance is adjusted to be equivalent to that in FIG. 3.

In this way, in addition to the original light diffusion function of the diffusion plate 6,
In the present invention, the display device also has the function of diffusing heat generated from the FL tube, thereby making it possible to reduce the thickness of the conventional display device without deteriorating its functions.

〔Effect of the invention〕

As explained above, the present invention incorporates glass with high thermal conductivity into the conventional diffuser plate to eliminate uneven temperature distribution on the surface of the liquid crystal display element that accompanies thinning, thereby producing a thin liquid crystal display device with no uneven screen contrast. can be obtained.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of a liquid crystal display device, Fig. 2 is an assembled sectional view of the liquid crystal display device of Fig. 1, Fig. 3 is a cross-sectional model diagram of a conventional diffuser plate, and Fig. 4 is a diffuser plate of the present invention. FIG. ! ...Liquid crystal display element 4...FL backlight unit 6...Diffusion plate 8...FL tube 9...Lamp housing 10...Glass body or more Applicant Seiko Electronic Industries Co., Ltd. Agent Patent attorney Keiyuki Hayashi Figure 2, Figure 83, Figure 107) 'Fuzu cross-pollinated particles' Figure 4

Claims (1)

[Claims] A liquid crystal display comprising a liquid crystal element, a printed circuit board on which an IC chip for driving the liquid crystal element is mounted and connected to the liquid crystal element by a flexible board, and a backlight unit arranged on the back side of the liquid crystal element to illuminate it. A liquid crystal display device, wherein the diffuser plate of the backlight unit contains a glass component.