JPH04293035A - Light source unit for projection type liquid crystal television - Google Patents

Abstract

PURPOSE:To offer the light source unit which is easily and instantaneously turned on again after continuously illumination and reduced in the frequency of replacement of a lamp due to a decrease in brightness depending upon the life as to a light source unit for a projection type liquid crystal television which uses metal halide lamps. CONSTITUTION:The light source unit consists of plural metal halide light sources 1a and 1b, an air blowing fan 9 for cooling the lamps, a converter 6 which switches the optical path according to which of the light sources 1a and 1b which is turned on, and a controller 13 which selects the illumination order of the light sources through temperature sensors 5a and 5b and illumination time integrating counters 12a and 12b provided for the light sources 1a and 1b. The instantaneous re-illumination after continuous illumination which is difficult when a single metal halide light source is used can easily be realized and the lamps are made uniform in cumulative illumination time to reduce the frequency of replacement of the lamps due to the natural brightness decrease.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a light source device used in a projection type liquid crystal television, in which an image on a transmission type liquid crystal panel is irradiated from the back side using a metal halide lamp as a light source, and is enlarged and projected using a projection lens. .

0002

2. Description of the Related Art In recent years, projection-type liquid crystal televisions have been attracting attention, in which images on a transmission-type liquid crystal panel are irradiated from the rear with a light source lamp and enlarged and projected using a projection lens.

For example, in a projection type liquid crystal television, (FIG. 4)
As shown in the figure, the light emitted from the light source 1a is separated into three primary color lights by the dichroic mirror 11,
, B are irradiated onto the three liquid crystal panels 16 that form the images. The light transmitted through the panel 16 is again combined by the dichroic mirror 11 and then enlarged and projected onto the screen by one projection lens 17, or as shown in FIG. The book is configured to be enlarged and synthesized on a screen using a projection lens 17. The light source lamp has high production light, high luminous efficiency,
Metal halide lamps were often used because of their long lifespan.

In the figure, 2 is an arc tube, 3 is a reflector, and 4 is a light emitting tube.
is a case, 6 is a mirror, 10 is a filter, 14 is a mirror, and 15 is a field lens.

[0005]

[Problems to be Solved by the Invention] As described above, metal halide lamps are used as light source lamps for conventional projection type LCD televisions, but metal halide lamps cannot be lit if the temperature of the lamp is high during lighting. When relighting after continuous use, it was necessary to provide a cooling time of about 1 to 5 minutes or to apply a high voltage of about 40 kV.

[0006] Furthermore, the brightness of the metal halide lamp is 1
After 000 to 2000 hours of use, it will be halved.
1/5th to 1/5th of conventional cathode ray tube projection television.
Since the lifespan is only 2 hours, the lamp will need to be replaced.

In view of the above-mentioned problems, the present invention provides a light source device for a projection type liquid crystal television that uses a plurality of lamps in the light source device so that it can be easily relit after continuous use and the lamps need to be replaced less frequently. This is what we are trying to provide.

[0008]

[Means for Solving the Problems] A light source device for a projection type LCD television according to the present invention includes a plurality of light source lamps, a temperature sensor that measures the temperature of each lamp, and a control that selects a lamp to be lit based on the value of the temperature sensor. It is characterized by consisting of a circuit and an exchanger that switches the optical path according to the lighting lamp.

Further, in the present invention, in addition to the temperature sensor, a counter is provided for accumulating the lighting time of the lamp, and the lamp to be lit is selected based on the values of both the temperature sensor and the accumulation counter.

0010

[Function] According to the light source device of the present invention, by selecting and using a plurality of lamps, it is possible to construct a projection type LCD television that can be easily relit after continuous use and requires less frequent replacement of lamps. It is something.

[0011]

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, 1a and 1b are light source lamps (metal halide lamps), which are composed of an arc tube 2, a reflector 3, and a case 4 in which they are fixed.
Temperature sensors 5a and 5b each measure lamp temperature
is installed. 12a and 12b are light source lamps 1
This is a counter that adds up the lighting times of the light source lamps 1a and 1b, and is used to determine the lighting order so that the cumulative lighting times of the light source lamps 1a and 1b are approximately the same. 6 is a mirror for converting the optical path when switching the light source lamp to be lit;
7 is an actuator that rotates the mirror 6, 8a, 8
b is a stopper for positioning the mirror 6, and these constitute an optical path exchanger. Reference numeral 9 denotes a cooling fan that lowers the lamp temperature after lighting to a temperature at which lighting is possible. The mirror 6 reflects the light from the lamps 1a and 1b toward the dichroic mirror 11, and also reflects the wind from the cooling fan 9 to efficiently cool the lamp after it has been turned off. Reference numeral 13 denotes a control circuit that selects the lamp to be lit, switches the optical path, and controls the cooling fan 9 based on the lamp temperature measured by the temperature sensors 5a and 5b and the cumulative lighting time calculated by the integration counters 12a and 12b. It is.

In order to decide which of the light source lamps 1a and 1b to turn on when lighting the lamp, the temperature of each lamp is first measured by the temperature sensors 5a and 5b, and the lamp whose temperature is below the allowable lighting temperature is selected. If the temperature of both lamps is above the lighting temperature, the one with the lower temperature is selected, and if it is below the lighting temperature, the integration counter 1 is selected.
The one with the shorter cumulative lighting time of 2a and 12b is selected. At this time, if the temperature of the lamp that is not lit is equal to or higher than the temperature that allows lighting, the cooling fan 9 operates to lower the lamp temperature. The cooling fan 9 stops when the lamp temperature falls below the lighting temperature, and the lamps that are not lit are always kept at a temperature below the lighting temperature. Control circuit 1 controls these functions.
3 is accomplished.

(FIG. 1) shows a state in which the light source lamp 1a is lit. At this time, the light source lamp 1b is cooled by the cooling fan 9 and prepared to a temperature below which it can be lit. In this state, if the lamp 1a is turned off and then turned on again, the conventional light source lamp cannot be turned on until the lamp temperature drops, but in the light source device with such a configuration, as shown in FIG. The light source lamp 1b is immediately turned on, and at the same time, the mirror 6 is also switched so that the light from the light source lamp 1b is directed toward the dichroic mirror 11. At this time, the light source lamp 1a is cooled down by the cooling fan 9 and prepared to have a temperature below which it can be lit.

In addition, since the light source lamps to be lit are selected so that the difference in cumulative lighting time is small between both light source lamps, there is little difference in brightness when the light source lamps are switched midway through their lifespans, which is better than the conventional example. Compared to conventional lamps, there is no discomfort, the lamp life is twice as long, and the frequency of lamp replacement can be halved.

FIG. 3 shows an example in which this configuration is used in a light source device for a three-lens projection type liquid crystal television as shown in FIG. 5. In this embodiment, since there is no mirror for switching the optical path, the light source lamps 1a and 1b are rotated by the actuator 7 and directly replaced.

In the embodiment of FIGS. 1 and 3, two light source lamps are used, but of course more lamps can be used.

[0017]

As described above, according to the light source device of the present invention, by using a plurality of light source lamps, a temperature sensor, a cooling fan, an optical path switch, and a control circuit for controlling these, Instantaneous re-lighting after continuous lighting is easily possible.

Further, by using a counter for accumulating the lighting time, it is possible to suppress the discomfort when switching the light source lamp as much as possible, to extend the apparent life of the lamp, and to keep the frequency of replacement low.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a light source device for a projection type liquid crystal television according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a light source device for a projection type liquid crystal television according to an embodiment of the present invention in a state different from that shown in FIG. 1.

FIG. 3 is a perspective view of a light source device for a projection type LCD television according to another embodiment of the present invention.

[Fig. 4] Cross-sectional view of a conventional light source device for a one-lens projection type LCD television.

[Fig. 5] A perspective view of a conventional light source device for a three-lens projection type LCD television.

[Explanation of symbols]

1a Light source lamp 1b Light source lamp 2 Arc tube 3 Reflector 4 Case 5a Temperature sensor 5b Temperature sensor 6 Mirror 7 Actuator 8a Stopper 8b Stopper 9 Cooling fan 10 Filter 11 Dichroic mirror 12 Counter 13 Control circuit 14 Mirror 15 Field lens 16 LCD panel 17 Projection lens

Claims (2)

[Claims] Claim 1: In a projection type liquid crystal television in which an image on a transmissive liquid crystal panel is irradiated from the back side by a light source and enlarged and projected by a projection lens, a plurality of light sources and one of the plurality of light sources are selected. A lamp exchanger that switches the light path, an air blower that cools the light source after use, a temperature sensor that measures the temperature of the light source, and a control device that selects the light source to turn on based on the temperature detected by the temperature sensor. A light source device for projection type LCD televisions. [Claim 2] In addition to the temperature sensor, a counter is provided to count the cumulative lighting time of each light source, and this counter
2. The light source device for a projection type liquid crystal television according to claim 1, further comprising a control device for selecting a light source to be turned on based on the numerical value of and the temperature detected by the temperature sensor.