JPH0724775Y2 - Light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a light source device including a short arc type metal halide discharge lamp.

[Conventional technology]

In a short arc type metal halide discharge lamp that is lit by alternating current, bright points are formed at the tips of a pair of electrodes that face each other. Therefore, when such a short arc type metal halide discharge lamp is used in combination with a converging reflecting mirror such as a parabolic reflecting mirror, the tip of one electrode is arranged so as to match the focal point of the reflecting mirror. In this case, the radiated light from the bright spot formed at the tip of the other electrode makes the illuminance distribution on the surface to be irradiated extremely uneven, and the light utilization rate is considerably reduced.

Conventionally, in a light source device including a discharge lamp as a light source lamp, as a means for improving the illuminance distribution on a surface to be illuminated, the surface on the reflecting mirror side in the bulging portion forming the light emitting space of the envelope is a frosted surface. Are known (Japanese Utility Model Publication No. 62-149160 and Japanese Patent Application Laid-Open No. 2-40852).

[Problems to be solved by the device]

However, even in the conventional light source device as described above, it is not possible to sufficiently improve the illuminance distribution when light spots are formed at the tips of the pair of electrodes in the light source lamp, or There is a problem that the utilization rate is low.

The present invention has been made based on the above circumstances, and an object thereof is to provide a short arc type metal halide discharge lamp in which a bright spot is formed at each tip of a pair of electrodes, and to achieve a high light utilization rate. An object of the present invention is to provide a light source device which is obtained and has a high uniformity of illuminance distribution on the illuminated surface.

[Means for Solving the Problems]

The light source device of the present invention has a sealing body having a bulging portion which forms a light emitting space formed in the center, and a pair of electrodes are arranged to face each other in the bulging portion of the sealing body, and is turned on by alternating current. A short arc type metal halide discharge lamp in which a bright spot is formed at the tip of each electrode and a concave reflector whose reflection surface extends along a paraboloid are arranged in combination with this short arc type metal halide discharge lamp. In the short arc type metal halide discharge lamp, the tips of the pair of electrodes are located on the optical axis of the concave reflecting mirror, and the tips of one electrode approaching the concave reflecting mirror are the focal points of the concave reflecting mirror. And the surface on the other electrode side of the bulging portion of the envelope of the short arc type metal halide discharge lamp is a frosted surface.

[Action]

According to such a configuration, the light emitted from the bright spot at the tip of one electrode on the concave reflecting mirror side is projected by the concave reflecting mirror as light with high parallelism, and at the same time, the bright spot at the tip of the other electrode is projected. A considerable part of the light emitted from the frosted surface is suppressed from being diffused by the frosted surface and being condensed in the central region of the irradiated surface.

[Specific configuration of device]

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a light source device according to an embodiment of the present invention. In this figure, 10 is a concave reflecting mirror whose cross section has a reflecting surface 11 extending along a parabolic surface. Reference numeral 20 is a short arc type metal halide discharge lamp, which has a sealing body composed of a bulging portion 21 forming a central light emitting space and sealing side tube portions 22 and 23 at both ends, and inside the bulging portion 21. A pair of electrodes 25, 26 are arranged to face each other, and metal foils 27, 28 connected to the pair of electrodes 25, 26 are sealed in the respective sealing side tube portions 22, 23. 29 and 30 are external leads. This metal halide discharge lamp 20 is lit by alternating current and has a pair of electrodes.
Bright spots are formed at the tips of 25 and 26, respectively.

In the metal halide discharge lamp 20, the one side tube portion 22 is inserted into the central cylindrical portion 12 of the concave reflecting mirror 10, and the pair of electrodes 25 and 26 face each other on the optical axis X of the concave reflecting mirror 10. And the electrode extending from the one side tube portion 22, that is, the tip of the one electrode 25 approaching the concave reflecting mirror 10 is substantially aligned with the focal point F of the concave reflecting mirror 10,
It is arranged in combination with 10. The surface of the bulging portion 21 of the envelope of the metal halide discharge lamp 20 surrounding the other electrode 26, that is, the front side portion is the frost surface 40.

With such a configuration, one bright point formed at the tip of the one electrode 25 substantially coincides with the focal point F of the concave reflecting mirror 10, so that the emitted light from this one bright point is As indicated by the chain line in FIG. 1, the light reflected by the concave reflecting mirror 10 and projected forward as light parallel to the optical axis X, and the light that directly travels forward of the emitted light from one of the bright spots is , Is diffused by the frosted surface 40 of the front part. At the same time, the other electrode
Since the other bright point formed at the tip of 26 is located in front of the focal point F of the concave reflecting mirror 10, most of the emitted light from this other bright point is diffused by the frosted surface 40 and slightly As shown by a broken line A, only a part of the light is bulged 21
From the clear rear side portion of the above, it advances toward the concave reflecting mirror 10, is reflected, and is condensed in the direction approaching the optical axis X. The frosted surface 40 of the bulging portion 21 acts as a light emitting portion having a relatively large area.

FIG. 2 is a curve diagram showing the relationship between the distance from the center position on the illuminated surface and the relative illuminance, and the curve I is due to the light source device of the above embodiment. Curve II is a case where the front surface of the bulging portion 21 is not a frosted surface and the whole is clear, and curve III is a case where the entire bulging portion 21 is a frosted surface.

As is clear from FIG. 2, according to the light source device of the above-described embodiment, the illuminance distribution is largely uniformized as compared with the case where the whole is clear. This is because, as shown by the broken line B in FIG. 1, a considerable part of the light that should go to the central area of the irradiated surface when there is no frosted surface 40 is diffused by the frosted surface 40, and the central area of the irradiated surface. This is because the illuminance of is effectively suppressed.

FIG. 3 shows an illuminance ratio (average of illuminance at a plurality of peripheral positions with respect to the illuminance value at the center position) in a light irradiation area having a diameter of 80 mm on the irradiated surface when the light source device is brought closer to the irradiated surface. Value ratio) and the relative value of the luminous flux (the maximum value is 100
Is a curve diagram showing the relationship between
Is the light source device of the above embodiment, and the curved line B is the bulging portion 21.
When the whole is clear, the curve C is the case where the entire bulging portion 21 is the frosted surface.

From FIG. 3, according to the light source device of the above-described embodiment, it is possible to obtain a high luminous flux and a high illuminance ratio, that is, the light utilization rate is high and the illuminance distribution is uniform on the illuminated surface. Is understood to be high.

More specifically, for example, in a light source device that is a backlight device that illuminates a liquid crystal display panel from behind, it is necessary that the illuminance ratio is about 25% or more, but the entire bulging part is clear. With a metal halide discharge lamp having a different envelope, an illuminance ratio of 25% or more cannot be obtained unless the luminous flux is small as shown by the curve B. Further, in the case where the entire bulging portion is the frosted surface, the illuminance ratio is sufficient as shown by the curve C, but the luminous flux is small and the light utilization rate is extremely low. On the other hand, according to the light source device of the above-described embodiment, it is possible to execute illumination with a large luminous flux and a high illuminance ratio as indicated by the curve A, and it is suitable as a backlight device for a liquid crystal display.

〔effect〕

As described above, according to the present invention, a short arc type metal halide discharge lamp in which a bright spot is formed at each tip of a pair of electrodes is provided, and the emitted light from one bright spot on the concave reflecting mirror side is a parallel light. The light emitted from the other bright spot is effectively suppressed from being diffused by the frosted surface and condensed in the central area of the illuminated surface, so that high light utilization is possible. It is possible to provide a light source device which has a high rate and has a high uniformity of illuminance distribution on the surface to be illuminated.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing the configuration of a light source device according to an embodiment of the present invention, and FIG. 2 compares the relationship between the distance from the center position on the illuminated surface and the relative illuminance by the light source device of the present invention. And FIG. 3 is a curve diagram showing the relationship between the illuminance ratio in the light irradiation area and the relative value of the light flux when the light source device of the present invention is brought closer to the surface to be irradiated. . 10 ... Concave reflecting mirror, 11 ... Reflecting surface 12 ... Center tube part 20 ... Short arc type metal halide discharge lamp 21 ... Swelling part 22,23 ... Side side tube part 25,26 ... Electrode, 27,28 ... Metal foil 29,30 ... External lead, 40 ... Frost surface X ... Optical axis, F ... Focus

Claims (1)

[Scope of utility model registration request] 1. A bulging portion forming a light emitting space has a sealing body formed in the center, and a pair of electrodes are arranged facing each other in the bulging portion of the sealing body, and are turned on by alternating current. A short arc type metal halide discharge lamp in which a bright spot is formed at the tip of each electrode and a concave reflecting mirror in which the short arc type metal halide discharge lamp is arranged in combination and whose reflecting surface extends along a paraboloid In the short arc type metal halide discharge lamp, the tips of the pair of electrodes are located on the optical axis of the concave reflecting mirror, and the tips of one of the electrodes approaching the concave reflecting mirror are almost at the focal point of the concave reflecting mirror. A light source device, wherein the surface of the envelope of the short arc type metal halide discharge lamp, which is arranged so as to coincide with the other electrode side, is a frosted surface.