JPH04269441A - Metal halide lamp device - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp device, requiring no spherical mirror, allowing simple exchange of an arc tube, having a long life, and having good spectral characteristics. CONSTITUTION:A reflecting film 4 is formed on about a half of the wall surface of a metal halide arc tube 1 in its axial direction. Ventilation is made from an air blower 5 toward the reflecting film formed surface of the arc tube 1, through a blower hood 6, so as to cool the reflecting film forming surface of the arc tube 1 compulsively, thus preventing deformation thereof.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp device, and more particularly to a metal halide lamp device that is combined with an optical lens and used as a light source for relatively small optical equipment that distributes light in an optically limited area.

0002

[Prior Art] Conventionally, a metal halide lamp device used as a light source for optical equipment and video equipment such as overhead projectors has a metal halide arc tube that emits light, and a spherical mirror with a cold mirror attached to the rear of the metal halide lamp device. A method is adopted in which a reflecting mirror is disposed to reflect back rays that are not directly emitted toward an aspherical lens disposed at the front, and the aspherical lens converts the light into parallel light.

FIG. 2 shows an example of the configuration of a metal halide lamp device used as a light source for such conventional optical equipment. In the figure, 1 is a metal halide arc tube with a rating of 150 W that is filled with a metal halide mainly composed of Dy-Nd, and when turned on using an electronic ballast with a square wave of 270 Hz, the total luminous flux is 12000 lm, and the color rendering index Ra: 85
, special color rendering index R9: exhibits high luminous efficiency and high color rendering properties of 60. A spherical mirror 2 is provided to surround the arc tube 1, and a cold mirror made of silica/titania is provided on the surface of the spherical mirror 2 facing the arc tube. This spherical mirror 2 has the function of reflecting the light emitted from the arc tube 1 and returning it to the arc tube 1, and also has the role of transmitting infrared rays (heat rays) emitted from the arc tube 1 to the outside. An aspherical condenser lens 3 is installed on the opposite side of the arc tube 1 from the spherical mirror 2, and part of the light emitted directly from the arc tube 1 is emitted from the arc tube 1 via the spherical mirror 2. It has the function of concentrating light and shaping it into parallel light.

[0004] When constructing an overhead projector using the metal halide lamp device configured as described above, a Fresnel lens is used to condense the light emitted from the aspherical lens 3 of the metal halide lamp device at a further distant position; It consists of a projection lens placed further away so as to enlarge the original image placed on the Fresnel lens surface.

[0005]

[Problems to be Solved by the Invention] By the way, the metal halide lamp device constructed as described above is generally popular due to its high efficiency. If you do not set the placement position accurately, you will not be able to obtain the designed illuminance.Also, when replacing the arc tube when the arc tube is defective, the replacement work space is small and the work is difficult, and the positioning accuracy is difficult. Another problem was that it was difficult to maintain good reproducibility.

On the other hand, in conventional metal halide arc tubes, in order to prevent unevaporated additives from accumulating in the coldest part during lighting, one side, which becomes the coldest part, is A heat-insulating and reflective film is provided on the wall of the arc tube where the electrodes are placed. Therefore, the heat insulating and reflective film provided in this coldest part is provided on one entire surface of the arc tube in the axial direction.
It has also been proposed that the reflective film has the function of a spherical mirror.

However, if a reflective film is formed on the entire surface of one side in the axial direction of the arc tube, since this type of metal halide arc tube is originally designed to be compact, the wall surface of the arc tube where the reflective film is formed will become hot. As a result, the product expands early during its life, resulting in a decrease in illuminance, and the vapor pressure of the added luminescent material becomes too high during the initial luminescence, making it impossible to obtain the desired spectral distribution and significantly reducing commercial value. There was a problem.

The present invention has been made to solve the above-mentioned problems in conventional metal halide lamp devices, and has a long life and good spectral characteristics without causing deformation of the arc tube, without requiring a spherical mirror. The purpose of the present invention is to provide a metal halide lamp device.

[0009]

[Means and Effects for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a metal halide arc tube in which a reflective film is provided on approximately half of the wall surface in the axial direction of the arc tube without using an outer tube; A metal halide lamp device is constituted by a blowing means for blowing forced air toward the surface on which the reflective film is formed of the arc tube.

[0010] In the metal halide lamp device constructed in this manner, the reflective film forming surface of the arc tube is forcibly cooled by air blowing means. Therefore, deformation due to high temperature on the reflective film forming surface of the arc tube is prevented, and the desired vapor pressure can be obtained.This eliminates the need for a spherical mirror, making it easy to replace the arc tube, and the metal halide has a long life and the desired spectral distribution. A lamp device can be easily realized.

[0011]

[Example] Next, an example will be explained. FIG. 1 is a diagram showing an embodiment of a metal halide lamp device according to the present invention. In the figure, numeral 1 is a metal halide arc tube with a rating of 150 W, which is filled with a metal halide mainly composed of Dy-Nd, as in the conventional case, and an aspherical lens 3 is disposed in front of the tube. A reflective film 4 made of an alumina-silica mixture is formed on the wall surface of the arc tube 1 except for the incident angle range of the emitted light to the aspherical lens 3 of the arc tube 1. 5
is a blower fan; 6 is a blower hood for guiding the air from the blower fan 5 to the reflective film forming surface of the arc tube 1;

In the metal halide lamp device constructed as described above, when the lamp device is lit, air from the blower fan 5 is blown through the air hood 6 onto the reflective film formed surface of the arc tube 1, thereby causing the reflective film formed surface to Since temperature rise is prevented by forced air cooling, deformation is effectively prevented.

In order to compare with the above-mentioned embodiment of the present invention, air was blown toward the wall surface of the arc tube 1 on which the reflective film 4 was not formed, and the wind speed was adjusted such that the reflective film formed surface of the arc tube 1 would not be deformed. When this was selected, the vapor pressure of the additive decreased too much, the desired luminescent characteristics could not be obtained, and the color characteristics deteriorated.

On the other hand, as in this embodiment, the arc tube 1
It has been found that when air is blown toward the surface on which the reflective film is formed at a speed that does not cause deformation, a good additive vapor pressure can be obtained and the color characteristics are significantly improved without being impaired. This is because by applying the reflective film 4 to the arc tube 1, the temperature distribution on the wall surface of the arc tube is such that the side where the reflective film is formed is higher in temperature than the side where the reflective film is not formed, and that part is cooled by blowing air. This is because by doing so, it is possible to return to an appropriate temperature distribution similar to that in the case where no reflective film is provided.

In the above embodiment, the reflective film 4 is attached to the arc tube 1.
In the example shown above, the reflective film is formed on the wall surface excluding the incident angle range of the emitted light to the aspherical lens 3, but if this reflective film is formed on approximately half the wall surface in the axial direction of the arc tube, it can function as a spherical mirror. It can be made to stand.

[0016]

[Effect of the invention] As explained above based on the embodiments,
According to the present invention, a reflective film is formed on the arc tube to provide the function of an expensive spherical mirror, and the forced air cooling prevents deformation of the reflective film-formed surface of the arc tube, making it easier to replace the arc tube. It is possible to obtain a metal halide lamp device that is easy to use, has a long life, and has good spectral characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a metal halide lamp device according to the present invention.

FIG. 2 is a diagram showing a configuration example of a conventional metal halide lamp device.

[Explanation of symbols]

1 Metal halide arc tube 2 Spherical mirror 3 Aspherical lens 4 Reflective film 5　Blower fan 6 Ventilation hood

Claims (1)

[Claims] 1. A metal halide arc tube in which a reflective film is provided on approximately half of the wall surface in the axial direction of the arc tube without using an outer tube;
1. A metal halide lamp device comprising: a blowing means for forcing air toward a surface on which a reflective film is formed of the arc tube.