JPH0128577Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a lighting device used as an illumination light source for a liquid crystal display device or the like, and particularly to a lighting device using a cold cathode fluorescent tube (CCT).

[Conventional technology]

For example, in a transmissive liquid crystal display device, if the brightness of the illumination light source is set based on daytime brightness, the display will become dazzling when used at night; conversely, if nighttime is used as a standard, the brightness will be insufficient during the day, making the display difficult to see. Become.

For this reason, when cold cathode fluorescent tubes are used as illumination light sources, they are turned on directly in the daytime mode, and turned on through a dimming circuit in the nighttime mode to adjust the brightness.

By the way, the discharge of cold cathode fluorescent tubes becomes unstable at low temperatures, so countermeasures can be taken to prevent this.One possible solution is to install incandescent light bulbs and switch to incandescent light bulb lighting at low temperatures. That is, as shown in FIGS. 3 and 4, the reflector 1 has a shape of two paraboloids joined together.
Two cold cathode fluorescent tubes 2A and 2B are placed in parallel, and several light bulbs 3 are placed in a line between them.
Lighting is provided by A and 2B (lit directly during the day, and lit through a dimming circuit at night), and by light bulb 3 at low temperatures.

However, in that case, the incandescent bulb 3 is only used at low temperatures, and the reflector 1 is designed to efficiently reflect the illumination from the cold cathode fluorescent tubes 2A and 2B. Considering this, when the light bulb 3 is turned on, it does not emit surface light, and the display becomes unclear.

[Purpose of invention]

An object of the present invention is to provide a lighting device that emits surface light even when illuminated with a light bulb and can stabilize the discharge of a cold cathode fluorescent tube at low temperatures.

[Summary of the idea]

In the present invention, the reflector is formed so that the center part has a flat plate shape and the parts on both sides have curved surfaces.
A cold cathode fluorescent tube and several light bulbs are placed on the flat part of this reflector so that the bulbs are along both sides of the cold cathode fluorescent tube.A temperature sensor is attached to the cold cathode fluorescent tube, and the light bulb is set to a low temperature in night mode. The feature is that the cold cathode fluorescent tube in daytime mode is kept warm by being turned on at certain times and the heat generated by the lamp is turned on.

〔Example〕

1 and 2 show an embodiment of the present invention, in which 11 is a reflector having a flat plate-shaped portion 11A in the center and curved portions 11B on both sides, 12 is a cold cathode fluorescent lamp, 13 is several, for example 5
The cold cathode fluorescent tube 12 is attached to the center of the reflector 11 with the end of the reflector serving as a supporting part, and the electric bulbs 13 are arranged along both sides of the reflector. 14 is a temperature sensor (thermistor) attached to the cold cathode fluorescent tube 12;
If the temperature detected by this sensor 14 is below a certain set temperature, the light bulb 13 (mainly used for night lighting) is turned on and the generated heat is used to insulate the cold cathode fluorescent tube 12 (mainly used for daytime lighting). I try to use it for. Note that the light bulb 13 is dimmable.

With this configuration, the cold cathode fluorescent tube 12 lights up to provide illumination light in the daytime mode, and the lighting is switched to the light bulb 13 in the nighttime mode. In that case, if the ambient temperature is below a certain set temperature, the output of the temperature sensor 14 will control the light bulb 13 to turn on, and the heat generated by the light bulb 13 will keep the cold cathode fluorescent tube warm. The discharge of the cold cathode fluorescent tube 12 is stable even at low temperatures.

In addition, the light bulb 13 is turned on at night, and the display surface is uniformly illuminated by the illumination light.
Display becomes clearer.

〔effect〕

As described above, according to the present invention, when a cold cathode fluorescent tube and an incandescent lamp are used together as an illumination light source, the reflector is formed so that the center part is a flat plate and both sides are curved surfaces, and the flat part of the reflector is The light bulbs are placed along both sides of the cold cathode fluorescent tubes, the cold cathode fluorescent tubes are set to day mode, the light bulbs are set to night mode, and the light bulbs are turned on when the temperature is low and the heat generated is used to keep the cold cathode fluorescent tubes warm. I did it like this,
It serves as a surface light source both day and night, so you can expect good display. Moreover, the discharge of the cold cathode fluorescent lamp is stable even at low temperatures, and reliability is improved by making it easier to dim the light bulb.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a lighting device according to the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3 and 4 are a sectional view and a front view showing a conventional example. 11... Reflector, 11A... Flat plate part, 11B
...Curved surface portion, 12...Cold cathode fluorescent tube, 13...Light bulb, 1
4...Temperature sensor.

Claims (1)

[Scope of utility model registration request] A reflector is formed so that the central part is flat and the parts on both sides are curved.A cold cathode fluorescent tube and several light bulbs are attached to the flat part of the reflector, and light bulbs are placed on both sides of the cold cathode fluorescent tube. A temperature sensor is attached to the cold cathode fluorescent tubes so that the light bulbs in the night mode are turned on even when the temperature is low, and the generated heat is used to keep the cold cathode fluorescent tubes in the day mode warm. lighting equipment.