JPH11133876A - Illumination unit and liquid crystal display device with illumination unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination unit for a compact and highly reliable liquid crystal display device. SOLUTION: This illumination unit is constituted of a light guide plate 1, a fluorescent discharge tube 2, and a case 9, and a rubber holder 8 covering electrode leads part of the fluorescent discharge tube 2 is formed to L-shape, and the light guide position is fixed to the case 9 via the rubber holder 8 at two of the four corners of the light guide plate 1 at least. It is possible to obtain a high reliability against changes in temperature, humidity, impact, vibration, etc., by a simple constitution using a conventional rubber holder 8 without using special member although an entire size of the illumination unit is made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting unit used for a transmission type display device and the like, and a liquid crystal display device using the lighting unit.

[0002]

2. Description of the Related Art In recent years, display devices for information devices, such as notebook personal computers and word processors, and display devices for video devices, such as portable televisions, video movies, and car navigation systems, have become lighter and thinner.
Liquid crystal display devices have come to be widely used taking advantage of the feature of low power consumption. In addition, in order to realize a bright display screen, many of these liquid crystal display devices adopt a configuration in which illumination light is applied from behind a display element by a built-in illumination unit.

In this illumination unit, an edge light type in which a light guide plate is placed on the back surface of a display body and a linear light source such as a fluorescent discharge tube is arranged on an end surface of the light guide plate, or a direct type in which a light source is provided on the back surface of the display body. Broadly classified by method. When these two types are compared, the direct type method can obtain relatively high brightness but is not suitable for thinning, and the edge light method is thin and has excellent brightness uniformity of the light emitting surface, but is disadvantageous in terms of high brightness. It can be said.

[0004] As a method of a lighting unit of a liquid crystal display device used for a notebook personal computer or the like, an edge light method is often adopted with priority given to thinness.
Also, in a liquid crystal display device used for a video movie, a car navigation system, and the like, an edge light type using two or more fluorescent discharge tubes or an L-shaped fluorescent discharge tube in order to achieve both thinness and luminance. In many cases, an edge light method using a U-shaped fluorescent discharge tube is adopted.

FIGS. 6 and 7 show a conventional edge-light type illumination unit using an L-shaped fluorescent discharge tube. The lighting unit includes a flat transparent light guide plate 1 for transmitting light, an L-shaped fluorescent discharge tube 2 provided in close proximity to two of the four sides of the light guide plate 1, A reflection film 3 for guiding light emitted from the discharge tube 2 to the incident end face D of the light guide plate 1 is provided.

On the back surface of the light guide plate 1, a reflection sheet 4 is provided.
The reflection sheet 4 has a role of returning the light going out from the back surface of the light guide plate 1 back into the light guide plate 1 and increasing the illumination light coming out of the exit surface. . A diffusion sheet 5 is provided on the side of the light exit surface of the light guide plate 1 to increase the uniformity.

[0007] At both ends of the L-shaped fluorescent discharge tube 2,
Leads 6 for supplying a voltage from the outside are provided, and these leads 6 are connected by soldering or the like to lead wires 7 connected to a power supply unit such as an inverter that generates high-frequency AC. Generally, a high voltage is required to drive the fluorescent discharge tube 2, and in order to cover the exposed portions of the lead 6 and the lead wire 7 for ensuring safety,
Rubber holder 8A formed cylindrically with an insulator such as rubber
Is attached.

The light guide plate 1, the fluorescent discharge tube 2 and the like are held by a housing 9 to form an illumination unit.
The light guide plate 1 is provided with notches A at a pair of (two) corners on a diagonal line, and the ribs H on the housing 9 side are fitted into these notches A so that the light guide plate 1 Position is regulated. By forming the notch A in the light guide plate 1, the ribs H on the housing 9 side can be provided so as not to hinder the fluorescent discharge tube 2 and the rubber holder 8A. Is determined at a predetermined position, the position of the effective light emitting region L can be accurately maintained.

Further, by disposing the back cover 10 on the back side of the housing 9, the light guide plate 1, as an illumination unit, can be surely provided.
The fluorescent discharge tube 2 and the like are held and protected.

[0010]

As described above, the light guide plate 1
Is regulated by the rib H provided on the housing 9 side,
The ribs H on the light guide plate 1 and the housing 9 side are taken into account in consideration of the difference in the coefficient of thermal expansion between the light guide plate 1 and the housing 9, the difference in the water absorption rate, and the dimensional variation of each.
It is necessary to provide a gap S between the two. This gap S
If the light guide plate 1 does not exist or cannot be sufficiently secured, the light guide plate 1 expands in a high-temperature and high-humidity environment and is pressed against the housing 9, and the light guide plate 1 is deformed. There is a danger that the in-plane uniformity of the luminance of the image is greatly impaired.

Further, in order to form the notch A of the light guide plate 1, the size of the light guide plate 1 needs to be sufficiently large so that the notch A does not enter the effective light emitting area L. In comparison with the effective light emitting region L, the size becomes large.

When the gap S between the notch A of the light guide plate 1 and the housing 9 is sufficiently provided, the size of the entire lighting unit increases, and the distance between the light guide plate 1 and the fluorescent discharge tube 2 increases. In addition, since there is variation due to the gap S, there is a problem that the brightness and uniformity of the lighting unit are not stable.
Further, since the light guide plate 1 is not securely fixed due to the presence of the gap S, the housing 9 and the fluorescent discharge tube 2 reduce the load on the light guide plate 1 when vibration or impact force is applied to the lighting unit from the outside. There is a problem that it is easily damaged by receiving it.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lighting unit which is highly reliable against changes in temperature and humidity, shocks, vibrations, etc., while keeping the size of the entire lighting unit compact.

[0014]

In order to solve this problem, in an illumination unit according to the present invention, a rubber holder for covering an electrode lead portion of a fluorescent discharge tube is formed in an L shape, and four corners of a light guide plate are formed. In at least two of the corners, the position of the light guide plate with respect to the housing is fixed via the L-shaped rubber holder.

According to the present invention, it is possible to realize a highly reliable lighting unit against temperature and humidity changes, shocks, vibrations, and the like, while keeping the size of the entire lighting unit compact.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a fluorescent discharge tube is disposed near an incident side end face of a light guide plate, and a housing for holding the light guide plate and the fluorescent discharge tube is provided. Then, a rubber holder for covering the electrode lead portion of the fluorescent discharge tube is formed in an L-shape, and at least two of the four corners of the light guide plate are connected to the light guide plate with respect to the housing via the L-shaped rubber holder. The light guide plate has a fixed position, and the rubber holder is installed between the housing and the corners of the light guide plate with no gaps. Position is regulated, the relative position with respect to the housing is fixed with high accuracy, and the lighting unit can be designed to be relatively smaller than the effective light emitting area, and at the same time, the effective light emitting area of the light guide plate Picture frame from to Is also reduced, it is possible to set the size of the light guide plate small, it is possible to design the entire lighting unit more compact, and because the positional accuracy between the light guide plate and the fluorescent discharge tube also increases, Stable, uniform and efficient lighting can be performed, and even when the lighting unit is under high temperature and high humidity, the expansion of the light guide plate is absorbed by the elasticity of the rubber holder to prevent adverse effects on other members. In addition, even when strong external force such as vibration or impact is applied to the lighting unit, the heaviest light guide plate among the members constituting the lighting unit is prevented from rattling, and the fluorescent discharge tube and the housing are damaged. Can be minimized.

According to a second aspect of the present invention, there is provided a liquid crystal display device in which a transmission type liquid crystal display element is arranged on an emission end face of a light guide plate in the illumination unit according to the first aspect, and the whole is designed to be more compact. By combining the lighting units, a compact and highly reliable liquid crystal display device can be obtained.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) As shown in FIGS. 1 and 2, a transparent light guide plate 1 on a flat plate for transmitting light, and an L-shaped fluorescent member provided along an incident side end face D of the light guide plate 1 A discharge tube 2 and a reflection film 3 which collects light emitted from the fluorescent discharge tube 2 on the incident side end face D of the light guide plate 1 and guides the light toward the inside are arranged. The light guide plate 1 is formed of a material such as acrylic having an optimum optical characteristic represented by a transmittance and a refractive index necessary for light transmission.

The reflection sheet 4 is provided on the back surface of the light guide plate 1.
The reflection sheet 4 has a role of returning the light going out from the back surface of the light guide plate 1 back into the light guide plate 1 to increase the illumination light emitted from the emission surface.
Further, a dot pattern or a groove pattern (not shown) whose shape is changed according to the distance from the fluorescent discharge tube 2 is provided on the back surface of the light guide plate 1. Further, in the light guide plate 1, the light emitted from the illumination unit is equalized by the diffusion sheet 5 provided on the front surface side.

An L-shaped rubber holder 8 is attached so as to cover the leads 6 at both ends of the fluorescent discharge tube 2 and the connection portion (electrode lead portion) between the lead 6 and the lead wire 7.
These rubber holders 8 are formed of an elastic body such as an L-shaped rubber and an insulator, and are hollow so that the fluorescent discharge tube 2 and the lead wires 7 can enter therein. These rubber holders 8 insulate the exposed portions of the electrodes to ensure the safety of the device.

One lead wire 7 connected to the fluorescent discharge tube 2 is arranged along the L-shaped fluorescent discharge tube 2. Reflective film 3 made of white highly reflective material
Is wound around the fluorescent discharge tube 2 along the rubber holder 8 so as to keep a certain distance therefrom, and surrounds the fluorescent discharge tube 2, and the reflection film 3 is fixed to the light guide plate 1 by means such as adhesion. I have.

The housing 9 is formed of a resin molding material, and has a box shape so as to hold members such as the light guide plate 1 and the fluorescent discharge tube 2. An opening for extracting illumination light is provided at the center of the housing 9. An L-shaped rubber holder 8 made of an elastic material such as rubber is fitted without a gap between the outer peripheral wall 9a of the housing 9 and a pair (two) of diagonal corners of the light guide plate 1. It is installed in the state where it matched.

As a result, in the plan view of FIG. 1, the position of the light guide plate 1 is regulated without a gap in any of the left, right, up and down directions, and the relative position with respect to the housing 9 is fixed with high accuracy. The lighting unit can be designed to be relatively smaller with respect to the effective light emitting area L.

That is, when a lighting unit for a liquid crystal display device is considered, the effective light emitting area L of the lighting unit is generally set to be sufficiently large with respect to the effective image area of the liquid crystal panel in consideration of the variation of each member. It is necessary to
By increasing the relative positional accuracy of the light guide plate 1 and the housing 9,
This means that the effective light-emitting area L required for uniform illumination can be set smaller than before, thereby reducing the size of the entire illumination unit.

At the same time, the frame area from the effective light-emitting region L to the outer shape of the light guide plate 1 is naturally reduced, so that the size of the light guide plate 1 can be set small. Further, since there is no need to provide a notch for positioning in the light guide plate 1 or to install a rib for positioning the light guide plate 1 on the housing 9 side, the notch portion is affected by the loss as a light emitting area. Thus, the entire lighting unit can be designed to be more compact.

Further, not only the positional accuracy between the light guide plate 1 and the housing 9 but also the positional accuracy between the light guide plate 1 and the fluorescent discharge tube 2 are improved, so that uniform and efficient illumination can be performed more stably than before. it can.

Even when the lighting unit is under high temperature and high humidity, the expansion of the light guide plate 1 is absorbed by the elasticity of the rubber holder 8, thereby preventing other members from being adversely affected.

Further, even when a strong external force such as vibration or impact is applied to the lighting unit, by suppressing the backlash of the light guide plate 1 which is the heaviest among the members constituting the lighting unit, the fluorescent discharge tube 2 and the Damage to the housing 9 can be minimized.

A back cover 10 is provided on the back side of the housing 9.
By arranging the lighting unit, it is possible to reliably hold and protect the light guide plate 1, the fluorescent discharge tube 2, and the like as an illumination unit.

In the first embodiment, the case where the housing 9 is formed of a resin molding material has been described. However, the present invention is not necessarily limited to this material. For example, the housing 9 may be formed of a metal frame made of sheet metal. It is feasible.

In the first embodiment, the case where the L-shaped fluorescent discharge tube 2 is used has been described. However, the embodiment is not limited to the L-shaped fluorescent discharge tube, and a modified embodiment will be described below.

(Embodiment 2) As shown in FIG. 3, a pair of straight-type fluorescent discharge tubes 15 are arranged in parallel with each other along the incident side end face D of the light guide plate 1, and each fluorescent discharge tube 2
L-shaped rubber holders 8 are attached so as to cover the leads 6 at both ends of the lead wire 6 and the connection between the leads 6 and the lead wires 7. These rubber holders 8 are formed in an L-shape with an elastic body such as rubber, and are fitted without any gap between the outer peripheral wall 9 a of the housing 9 and each corner (four) of the light guide plate 1. is set up.

(Embodiment 3) As shown in FIG. 4, a U-shaped fluorescent discharge tube 1 is formed along the incident side end face D of the light guide plate 1.
The L-shaped rubber holder 8 is attached so as to cover the leads 6 at both ends of the fluorescent discharge tube 2 and the connection between the leads 6 and the lead wires 7. These rubber holders 8 are formed in an L-shape with an elastic body such as rubber, and are fitted without a gap between the outer peripheral wall 9 a of the housing 9 and a pair of adjacent corner portions (two places) of the light guide plate 1. It is installed in the state where it was done.

The pair of adjacent corners of the light guide plate 1 is the open side of the U-shaped fluorescent discharge tube 16.
On the opposite side, that is, on the closed side, notches A are provided at a pair of adjacent corners of the light guide plate 1, and the ribs H on the housing 9 side are fitted into these notches A.

Also in the third embodiment, the notch A is provided only on the side of the closed portion, and the notch A is not provided on the side of the open portion. The effect of the loss as a light emitting area due to
The entire lighting unit can be designed to be compact.

(Embodiment 4) FIG. 5 is a sectional view of a liquid crystal display device using an illumination unit according to the present invention. The lighting unit including at least the fluorescent discharge tubes 2, 15, 16 and the light guide plate 1, the reflection film 3, and the L-shaped rubber holder 8 described in the first to third embodiments is a shield case 11 and a liquid crystal. The liquid crystal display device is completed by being combined with the panel (transmission type liquid crystal display element) 12. At this time, the liquid crystal panel 12 is disposed on the end surface E of the light guide plate 1 on the emission side.

[0037]

As described above, according to the lighting unit of the present invention, the fluorescent discharge tube is arranged close to the incident side end face of the light guide plate, and the housing for holding the light guide plate and the fluorescent discharge tube is provided. To form an L-shaped rubber holder covering the electrode lead portion of the fluorescent discharge tube, and to fix the position of the light guide plate with respect to the housing via the rubber holder at at least two of the four corners of the light guide plate, With a simple structure using a conventional rubber holder without using special members, it can achieve high reliability against temperature and humidity changes, shocks, vibrations, etc., while reducing the size of the entire lighting unit. It is.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a lighting unit according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a configuration of the lighting unit.

FIG. 3 is a plan view showing a configuration of a lighting unit according to Embodiment 2 of the present invention.

FIG. 4 is a plan view showing a configuration of a lighting unit according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 6 is a plan view showing a configuration of a conventional lighting unit.

FIG. 7 is a cross-sectional view showing a configuration of the lighting unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 2 L-shaped fluorescent discharge tube 6 lead 7 lead wire 8 L-shaped rubber holder 9 case 9 a outer peripheral wall 10 back cover 11 shield case 12 liquid crystal panel (transmission type liquid crystal display element) 15 straight type fluorescent light Discharge tube 16 U-shaped fluorescent discharge tube A Notch H Rib D Incident end face E Exit end face L Effective light emitting area

Claims (2)

[Claims] 1. A rubber holder for disposing a fluorescent discharge tube in proximity to an incident side end face of a light guide plate, having a housing for holding the light guide plate and the fluorescent discharge tube, and covering an electrode lead portion of the fluorescent discharge tube. L
An illumination unit formed in a shape of a letter and fixing the position of the light guide plate with respect to the housing via the L-shaped rubber holder at at least two of the four corners of the light guide plate. 2. A liquid crystal display device according to claim 1, wherein a transmission type liquid crystal display element is arranged on an emission side end face of the light guide plate in the illumination unit according to claim 1.