JPH01167730A - Display device - Google Patents

Abstract

PURPOSE:To display all picture information even in case of such an abnormal case that part of a light source is absent by making the illumination state of the light source of a back light part and image information displayed on an image information display part correspond to each other. CONSTITUTION:When a 1st fluorescent lamp 13 has an absent point for some reason, the change of the absent point is detected by a 1st photodetection part 15 and an image signal generation part 11 includes image information of a part corresponding to the light emission surface of a back light 12 that light from the 1st fluorescent lamp 13 contributes to an image information of a part corresponding to the light emission surface of the back light 12 that light from a 2nd fluorescent lamp 14 contributes to as shown in a figure (c). The figure shows the compression of the information for including the information, but character information, etc., may be superposed on one open space while changed in color. Consequently, the reliable display device is obtained which displays all image information even in an abnormal state where part of the light source becomes absent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to a display device that presents image information by changing the intensity distribution of illumination light from a backlight using a transmissive element such as a liquid crystal. It is.

2. Description of the Related Art A conventional display device will be explained using a device using a transmissive element such as a liquid crystal as an example.

In FIG. 5, 1 is a liquid crystal panel, 2 is a liquid crystal element driving section, 3 is an image signal generating section, and 4 is a backlight. However, the liquid crystal panel 1 is composed of a large number of liquid crystal display elements. By overlapping the backlight 4 and the liquid crystal panel 1, and changing the transmittance of each liquid crystal display element constituting the liquid crystal panel 1 by the liquid crystal element driving part 2 based on the output signal of the image signal generating part 3, light is emitted. It creates various patterns of spatial intensity distribution and presents these patterns as image information.

FIG. 6 shows an example of the structure of the backlight 4.

In FIG. 6, 5 is a first fluorescent lamp, 6 is a second fluorescent lamp, 7 is a reflector, and 8 is a diffuser.

A reflector plate 7 is provided below the fluorescent lamps 5 and 6 to efficiently condense the light emitted from the fluorescent lamps 5 and 6, and to combine the direct light from the fluorescent lamps 5 and 6 and the reflected light from the reflector plate 7. By irradiating the diffuser plate 8 with the light, a planar light source with high brightness and high brightness uniformity is realized.

The side of the diffusion plate 8 opposite to the side on which the fluorescent lamps 5 and 6 are arranged is the light emitting surface of the backlight 4. In the diffuser plate 8, the direct image of the fluorescent lamps 5 and 6 is erased by increasing the thickness of the diffuser plate 8 or locally providing a dot pattern in the portion corresponding to the positive column portion of the fluorescent lamps 5 and 6. Some improvements have been made. However, the same type of fluorescent lamps 5 and 6 are usually used in order to improve the brightness uniformity of the light emitting surface of the backlight 4. In addition, in order to improve the luminous efficiency and make the device thinner, lamps whose discharge path is lengthened by bending or joining one end of a plurality of positive column parts (for example, Japanese Patent Application Laid-Open No. 188405/1982) have been developed with a rectangular shape. It is being put into practical use as a light source for backlights.

Problems to be Solved by the Invention In the backlight 4 configured as described above, the lamp tube diameter direction (transverse direction of the tube diameters of the fluorescent lamps 5 and 6)
The upper surface of the diffuser plate 8 (light emitting surface of the backlight 4)'
The 1% brightness distribution is shown by the solid line in Figure 7. When the fluorescent lamps 5 and 6 are both lit, as shown by the solid line in Figure 7, it is a planar light source with high brightness and high brightness uniformity. can do.

However, there has been a problem in that when either the fluorescent lamps 5 or 6 are turned off, the brightness uniformity is significantly reduced. The brightness distribution on the light emitting surface of the backlight 4 when the first fluorescent lamp 1 is turned off (in an abnormal situation) is shown in the broken line in FIG. 7. As shown in the broken line in FIG. - If the light goes out for some reason such as an impact, the brightness will drop significantly on about half of the light emitting surface of the backlight 4. When such a backlight is combined with a liquid crystal panel and used as an information display device for aircraft or automobiles. As mentioned above, if one of the lamps goes out, about half of the display goes dark, making it impossible to convey sufficient information to the pilot.
There was a problem in that the display device was in a dangerous state that made it unusable.

The decrease in brightness uniformity during abnormal situations such as when either the fluorescent lamps 5 or 6 goes out can be improved by separating the fluorescent lamps 5 and 6 sufficiently from the reflector plate 7 and the diffuser plate 8. There was a problem in that it was not possible to make the device thinner. There is also a method of lighting a luminous flux compensation light source placed in advance in the backlight lighting equipment, but this method requires different types of lamps and lighting circuits to drive them in the backlight lighting equipment, which is expensive and expensive. There was a problem that maintenance was time-consuming.

Means for Solving the Problems The present invention includes a backlight unit including a plurality of light sources, a lighting state detection unit that detects the lighting state of the light sources of the backlight unit, and a lighting state detection unit that detects the lighting state of the light source of the backlight unit, and a device that transmits or transmits the irradiated light from the backlight unit. and an image information display section that displays image information by shutting off, and the lighting state of the light source of the backlight section is always made to correspond to the image information displayed by the image information display section.

Effect: With the configuration as described above, all image information can be presented even in an abnormal situation where a part of the light source becomes a defect.

Embodiment FIG. 1 shows a configuration diagram of an embodiment of a display device according to the present invention. In FIG.
3 is a first fluorescent lamp, 14 is a second fluorescent lamp, 15
1 is a first light receiving section, and 16 is a second light receiving section.

An embodiment of the present invention will be described with reference to FIG. 2 in a case where the first fluorescent lamp 13 becomes defective for some reason. If the first fluorescent lamp 13 and the second fluorescent lamp 14 in FIG. 1 are operating normally, the
As shown in a), an image is displayed as in the conventional example. In the conventional example, when the first fluorescent lamp 13 becomes defective,
As shown in FIG. 2(b), approximately half of the displayed image becomes invisible.6 In the present invention, the first fluorescent lamp 13
The first light receiving unit 15 detects the change in which the image becomes a defect, and the image signal generating unit 11 detects the change in the image signal as shown in FIG. 2(c).
Image information of a portion corresponding to the light emitting surface of the backlight 12 to which light from the first fluorescent lamp 13 contributes to image information of a portion corresponding to the light emitting surface of the backlight 12 to which light from the second fluorescent lamp 14 contributes Include in information. In Fig. 2, we explained how to include this information by compressing the information, but in the case of text information, it is also possible to overlay it in an open space with a different color. Not limited.

A second embodiment of the present invention is shown in FIG. 3. In FIG. 3, 17 is a first light receiving section, and 18 is a second light receiving section. However, it is assumed that a thin light-receiving element made of amorphous silicon and having a high transmittance for visible light is constructed. With this configuration, by arranging the fluorescent lamps 13 and 14 in the positive column portion facing the liquid crystal panel 9, the lighting state of the fluorescent lamps 13 and 14 can be monitored as in the first embodiment. As shown in FIG. 2, the lighting state can always be made to correspond to the image information displayed by the image information display section. Also,
Fluorescent lamps 13 and 1 are detected by light receiving sections 17 and 18.
Since a part of the light directly emitted from the fluorescent lamps 13 and 14 is absorbed, the direct image of the fluorescent lamps 13 and 14 can be softened, and this also serves as a means for reducing a decrease in brightness uniformity of the light emitting surface of the backlight 12.

A third embodiment of the present invention is shown in FIG. 4. In FIG. 4, reference numeral 19 indicates a current detection section of the first fluorescent lamp 13, and numeral 20 indicates a current detection section of the second fluorescent lamp 14. The lighting states of the fluorescent lamps 13 and 14 are monitored based on the signals from the current detection units 19 and 20, and the lighting states and image information displayed by the image information display unit are monitored as shown in FIG. can always be matched. Also,
The current detection units 19 and 20 are connected to the fluorescent lamps 13 and 14.
By including it in the drive circuit of , it is possible to have a simple configuration. Although the third embodiment of the present invention has been described as detecting the currents of the fluorescent lamps 13 and 14, it is also possible to detect other electrical characteristics (for example, lamp voltage) corresponding to the lighting states of the fluorescent lamps 13 and 14. A similar effect can be obtained.

Furthermore, in the first embodiment of the present invention, a changeover switch is provided in place of the light receiving sections 15 and 16, so that when one side of the backlight becomes dark, an observer viewing the displayed image can operate the changeover switch. , information presented on one side of the image may be included on the other side.

Although the present invention has been described using a liquid crystal display as an example of a display device, the present invention can be applied to any display device that uses a backlight composed of a plurality of light sources.

Effects of the Invention As described above, according to the present invention, it is possible to provide a highly reliable display device that can present all image information even in an abnormal situation where a part of the light source becomes defective.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a display device in an embodiment of the present invention;
Figure 2 is a diagram showing one method of displaying images using the same device;
4 are block diagrams of display devices in other embodiments, FIG. 5 is a block diagram of a display device using a conventional liquid crystal display, and FIG. 6 is a block diagram of a backlight of the same device.
FIG. 7 is a diagram showing the luminance distribution of the same backlight (the solid line shows the case where two lights are on, and the broken line shows the case when only one side is on). 11... Image signal generation section, 12... Backlight,
13.14...Fluorescent lamp, 15.16°17.18
. . . Light receiving section, 19.20 . . . Current detection section. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Figure 3 Figure 12 Back light Figure 4 Figure 5

Claims (3)

[Claims] (1) A backlight section consisting of a plurality of light sources, a lighting state detection section that detects the lighting state of the light sources of the backlight section, and displaying image information by transmitting or blocking the irradiation light from the backlight section. and an image information display section, wherein the lighting state of the light source of the backlight section always corresponds to the image information displayed by the image information display section. (2) The display device according to claim 1, wherein the lighting state detection section includes a light receiver that detects a part of the light emitted from the light source of the backlight section. (3) The display device according to claim 1, wherein the lighting state detection section includes a circuit system that detects electrical characteristics corresponding to the lighting state of the light source of the backlight section.