JPH09179119A - Back light system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve picture luminance without increasing power consumption especially at the time of outdoor usage concerning a back light for panel with which a transmissive or semitransmissive type display panel is irradiated from the back. SOLUTION: Concerning this system, one side of light transmission plate 1 composed of light transmissive materials is covered with a reflection plate 2, a light diffusion plate 3 is arranged on the other side at least, a linear light source 4 and a reflector 5 for reflecting light from that light source and guiding it to the light transmission plate 1 are provided, the reflection plate 2 is fixed on a 1st cover 12, the light transmission plate 1, light diffusion plate 3 and liquid crystal panel 11 are fixed on a 2nd cover 13, and the 1st cover 12 and 2nd cover 13 can be mutually rotated by a supporting point shaft 14. Especially when using this system outdoors, external light 17 is reflected on the reflection plate 2 and fetched into the light transmission plate 1 in addition to the quantity of light from the linear light source 4 so that the luminance of liquid crystal panel 11 can be improved without increasing power consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight system for a panel which illuminates a transmissive or semi-transmissive display panel from the back side.

[0002]

2. Description of the Related Art Recently, as a display device for a personal computer, a camera-integrated VTR, or the like, a thin liquid crystal display panel having a backlight function which is easy to see has been widely used.

FIG. 5 is a perspective view showing a basic structure of a conventional backlight disclosed in, for example, Japanese Patent Application Laid-Open No. 5-127159, in which a light guide plate 1 made of a translucent material is used.
One of the wide surfaces of the light guide plate 1 is covered with a mirror surface or a reflection plate 2, and the light diffusion plate 3 is arranged on the other light exit surface side of the light guide plate 1, and the linear light source 4 is provided close to at least one side surface portion of the light guide plate 1. And a reflector 5 for guiding the light from the linear light source 4 and the light from the light guide plate 1 to the light guide plate 1.
Is a backlight for a panel having, and is integrated by a fixing member (not shown). The light guide plate 1 is a substance that guides light from the linear light source 4 and the reflector 5 from the end portion and has a purpose of causing surface emission, and may be a substance that efficiently transmits light. For example, glass, quartz, or plastic is generally an acrylic resin system Is often used. A fluorescent tube is generally used as the linear light source 4 from the viewpoint of power consumption and color, and is boosted by an inverter circuit (not shown) and is lit at a high voltage. The light from the linear light source 4 enters the light guide plate 1, but the light emitted to the back of the linear light source 4 is reflected by the reflector 5 and enters the light guide plate 1 in a slit shape. The reflector 5 may be a metal plate that is mirror-finished or a sheet that is vapor-deposited with silver. The light introduced into the light guide plate 1 is reflected by, for example, the reflection plate 2 having an excellent light reflectance. Further, the reflection plate 2 is also attached to the first side face 6, the second side face 7, and the third side face 8 of the light guide plate 1, which is generally configured to minimize the leakage of light from the light guide plate 1 to the outside. is there. Although not shown, the light guide plate 1 is attached to the light guide plate 1.
It is also proposed that a pigment containing a light diffusing substance (titanium white or the like) having a high refractive index and a large diffuse reflectance as compared with the above material is applied in a dot shape by screen printing to correct the unevenness of light emitted from the light guide plate 1. ing. The light diffusing plate 3 is used to form a uniform surface light source because the light from the light guide plate 1 is reflected intricately, and a light diffusing material coated on a plastic sheet is used to cause irregular reflection. The light is emitted as a surface light source in the direction of arrow A.

FIG. 6 shows an external view of a conventional camera-integrated VTR equipped with a liquid crystal display panel. Basically, a VTR section 9 having a recording / reproducing function, a camera section 10 for capturing an image, and a camera section 10 for recording / reproducing are shown. It is composed of a liquid crystal panel 11 for displaying an image. The liquid crystal panel 11 is generally a transmissive liquid crystal panel, and the backlight described in FIG. 5 is arranged on the back surface of the liquid crystal panel 11.

[0005]

However, the camera-integrated VTR equipped with the liquid crystal display panel shown in FIG. 6 is often used not only indoors but also outdoors in recent years. In some cases, the illuminance is about 100,000 lux, and the screen of the liquid crystal display panel has a problem that the brightness is relatively lowered and the display screen is very difficult to see. As a countermeasure against this, it has been proposed to increase the current of the fluorescent tube or increase the number of fluorescent tubes to increase the incident light to the light guide plate, but both of them are accompanied by an increase in power consumption. In general, a camera-integrated VTR using a battery has a problem of battery life or heat generation.

Therefore, it is an object of the present invention to provide a backlight capable of obtaining high brightness of a liquid crystal display panel without increasing power consumption, especially when the liquid crystal display panel is used outdoors.

[0007]

The present invention has been made in view of the above problems and is based on the following means.

One wide surface of the light guide plate made of a translucent material is covered with a mirror surface or a reflection plate, and a light diffusing plate is arranged on the other light exit surface side of the light guide plate, and at least one side surface of the light guide plate is provided. In a panel backlight having a linear light source and a reflector for guiding light from the linear light source and light from the light guide plate in close proximity, the first invention can be separated at the boundary between the reflector and the light guide plate. A backlight system for a panel is provided, which has an opening / closing mechanism capable of performing an opening / closing operation.

A second aspect of the present invention is an opening / closing mechanism that can be separated at the boundary between the reflection plate and the light guide plate and can be opened / closed, a detector for detecting the open / closed state, and a switching drive for controlling the drive of the linear light source by the detector output. There is provided a panel backlight system comprising:

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention covers one wide surface of a light guide plate made of a translucent material with a mirror surface or a reflection plate, and the other one light exit surface side of the light guide plate. A light diffusing plate is disposed on the back surface of the liquid crystal panel, and the light source includes a linear light source in proximity to at least one side surface of the light guide plate, and a reflector for guiding the light from the linear light source and the light from the light guide plate to the light guide plate. In the light, the reflection plate is fixed to the first cover, the light guide plate, the light diffusion plate, and the liquid crystal panel are fixed to the second cover, and the first cover and the second cover are rotatably engaged with each other on the fulcrum shaft. It is configured such that it can be separated and opened / closed at the boundary between the reflection plate and the light guide plate, and when the first cover is open, in addition to the light emitted from the linear light source through the light guide plate. , There is a function to take in outside light from the opening with a reflector, especially for doors. In case the illuminance is large light emitted from the light guide plate to the display panel is improved panel brightness becomes more quantity linear light sources.

The invention according to claim 2 of the present invention comprises a detector for detecting the open / closed state of the first cover and the second cover, and a switching drive means for controlling the drive of the linear light source by the output of the detector. In the state where the first cover is open, the panel brightness is secured by the external light, and the driving of the linear light source is suppressed and controlled, so that the power consumption can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The detailed description of the same points as those of the conventional embodiment described with reference to FIG. 5 will be omitted.

(Embodiment 1) FIG. 1 is a side sectional view of a backlight for explaining the present invention. In FIG. 1, the light guide plate 1, the reflection plate 2, the light diffusion plate 3, the linear light source 4, and the reflector 5 are shown.
The operation is similar to the conventional operation described with reference to FIG. 5, and detailed description thereof will be omitted. The first cover 12 to which the reflection plate 2 is fixed by means of an adhesive or the like is provided with a hole (not shown) that engages with the fulcrum shaft 14 and can rotate about the fulcrum shaft 14 as a fulcrum. A hole (not shown) that engages with the fulcrum shaft 14 is provided in the second cover 13 to which the light guide plate 1, the light diffusion plate 3, and the liquid crystal panel 11 are integrally fixed, and the first cover 12 and the second cover 13 are provided.
Are rotatably engaged with each other at a fulcrum shaft 14 and separable at a boundary surface 15 between the reflection plate 2 and the light guide plate 1.
Further, the linear light source 4 and the reflector 5 may be fixed to either the first cover 12 or the second cover 13. Although the drive circuit and the wiring portion of the liquid crystal panel 11 and the linear light source 4 are functionally necessary, they are not necessarily shown in the illustration of the present invention and are not shown. With such a configuration, the light from the linear light source 4 is normally reflected by the reflector 5 and the reflecting plate 2, diffused by the light diffusing plate 3 and made incident on the liquid crystal panel 11, and the cover 16 provided on the second cover 13. An image of the liquid crystal panel 11 is obtained as transmitted light from.

FIG. 2 is a side sectional view of a backlight for effectively explaining the operation of the present invention when the liquid crystal panel 11 is used outdoors. In FIG. 2, the cover opening 23 is formed when the first cover 12 is rotated with the fulcrum shaft 14 as the fulcrum with the boundary surface 15 as the boundary. External light 17 such as sunlight can enter through the cover opening 23 when the first cover 12 is opened, and the external light 17 is reflected by the reflection plate 2 and enters the light guide plate 1. As a result, the amount of light incident on the liquid crystal panel 11 is increased, and the image brightness is improved. Of course, a part of the light that has entered the light guide plate 1 from the linear light source 4 is emitted from the boundary surface 15 of the light guide plate 1, but the amount of outside light 17 that is incident outdoors is predominantly large.
For example, sufficient brightness can be obtained even if the driving of the linear light source 4 is interrupted by a manual switch (not shown). When the outdoor weather is fine, the brightness of the liquid crystal panel 11 is approximately doubled when only the linear light source 4 is turned on by using the external light together with turning on the linear light source 4 in this configuration.

(Second Embodiment) FIG. 3 is a diagram for explaining a second embodiment of the present invention. The basic structure and the basic operation are the same as those in FIG. 1 and FIG. 2, and duplicated detailed description will be omitted.

The second cover 13 has a built-in micro switch which is a detector 18 for detecting the open / closed state of the first cover 12, and the first cover 12 is on the boundary surface 15 (closed state). Then, the contactor 19 is pushed in the C direction, and when the first cover 12 is opened as shown in FIG. 3, the contactor 19 projects in the B direction, and the open / closed state of the first cover 12 can be determined. The detection signal from the detector 18 controls the drive of the linear light source 4 with the transistor and the high-voltage inverter drive circuit as the switching drive means 20 in the open / closed state of the first cover 12. For example, in outdoor use, if the first cover 12 is opened in order to utilize the external light 17 such as sunlight, the operation of the linear light source 4 is interrupted by the action of the detector 18.
Even if the driving of the linear light source 4 is interrupted, sufficient image brightness can be obtained with the illuminance of the external light 17 as described with reference to FIG. As described above, when the outside light 17 is used, it is not necessary to drive the linear light source 4, power consumption can be reduced, and the battery life in the camera-integrated VTR as shown in FIG. The effect is great. Of course, the drive of the linear light source 4 may be controlled by a manual switch (not shown) regardless of the detection judgment of the detector 18. It is self-evident that driving the linear light source 4 and using the external light 17 in the state of FIG. 3 can improve the panel brightness as described with reference to FIG.

In the above description, the cover opening 23 is formed by opening and closing the first cover 12 or the second cover 13, but as shown in FIG. 4, the cover opening 23 is fixed, for example, the optical prism 21 or. The same operation can be performed by the combination of opening and closing the air and the third cover 22.

[0018]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, particularly in the use of a liquid crystal display panel or the like outdoors, in addition to the amount of light of a conventional fluorescent tube, a simple structure for incorporating outside light including ambient sunlight. Therefore, the brightness of the liquid crystal display panel can be increased without increasing the power consumption for driving the backlight. Further, low power consumption can be achieved without reducing the panel brightness.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a backlight structure according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing the same backlight operation.

FIG. 3 is a side sectional view showing a backlight structure according to a second embodiment of the present invention.

FIG. 4 is a side sectional view showing a backlight structure showing another embodiment of the present invention.

FIG. 5 is a perspective view showing a basic configuration of a backlight in a conventional example.

FIG. 6 is an external view of a conventional camera-integrated VTR equipped with a liquid crystal panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light guide plate 2 reflection plate 3 light diffusion plate 4 linear light source 5 reflector 11 liquid crystal panel 12 first cover 13 second cover 14 fulcrum shaft 15 boundary surface 16 cover 23 cover opening

Claims (2)

[Claims] 1. A light-diffusing plate made of a light-transmitting material is covered with a mirror surface or a reflecting plate on one wide surface, and a light diffusing plate is disposed on the other light-exiting surface side of the light-guiding plate, and at least one side surface of the light-guiding plate. In a backlight for a liquid crystal panel, which includes at least a linear light source, a light source of the linear light source, and a reflector that guides the light from the light guide plate to the light guide plate, the reflector is fixed to the first cover. The light guide plate, the light diffusion plate, and the liquid crystal panel are integrally fixed to the second cover, and the first cover and the second cover are rotatably engaged with each other by a fulcrum shaft. A backlight system for a panel, which is separable at a boundary surface and can be opened and closed. 2. The panel according to claim 1, further comprising a detector for detecting the open / closed state of the first cover and the second cover, and a switching drive means for controlling the drive of the linear light source by the output of the detector. Backlight system for.