JPH0869777A - Short arc metal halide lamp and optical device using the same - Google Patents

Abstract

PURPOSE: To provide a short arc metal halide lamp device which presents easiness in the works of manufacturing a light emitting tube where a low-cost material for trigger wire is used, good yield from production line, sturdiness of winding the trigger wire on the tube so that no slackening will occur even after a long time of service, and certain starting operation and starting characteristics. CONSTITUTION: At the ends of a light emitting tube 1, main electrodes 2a, 2b are attached sealedly while the arc is made or less in length and at least a metal halide is encapsulated in its inside so that a short arc metal halide lamp is formed, wherein a trigger wire 5 is wound on the tube and high voltage pulses are impressed to actuate the starting. The trigger wire is made from an iron wire which has been subjected in advance to an annealing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc metal halide lamp used in an optical device such as a liquid crystal projector or an overhead projector, and more particularly to an improvement of an arc tube of the short arc metal halide lamp used in a dark place in the device.

[0002]

2. Description of the Related Art Recently, a liquid crystal projector has been developed which is configured to project an image on a large screen by combining a liquid crystal panel and an optical system such as a lens. A light source device in which a short arc metal halide lamp and a parabolic reflector are combined as a backlight of the device has become mainstream from the viewpoint of ease of use, color reproducibility and brightness. Further, since this type of metal halide lamp has a small internal volume of the arc tube and a small sealing portion at both ends, it is difficult to seal the auxiliary electrode together with the main electrode in the sealing portion, and various kinds of metal halide lamps are required to facilitate starting. It has been devised.

As one method, a high-voltage pulse is applied to the electrodes of the arc tube to start the lamp when the lamp is started. Also, as a start-up assisting means, a thin heat-resistant metal wire is connected to the external lead led out from one electrode of the arc tube, and the thin wire is wound around the outer surface of the arc tube of the other counter electrode to be used as a trigger wire. ing. FIG. 2 shows a conventional example. 2 in the figure
Reference numeral 1 is a quartz arc tube, and the main electrodes 22a, 2 are provided on both ends thereof.
2b is sealed, and a metal halide is enclosed inside together with mercury and a rare gas. Further, a reflection and heat retention film 23 is applied to the outer peripheral surface of one electrode 22b of the arc tube. One end of the arc tube is fixed to the bottom of a bowl-shaped parabolic reflector 24 made of hard glass so that the optical axis of the reflector and the tube axis of the arc tube coincide with each other. Further, a trigger wire 25 made of a thin wire such as iron is provided on the outer circumference of the arc tube, one end of the trigger wire is connected to an external lead 26 led out from one electrode 22b, and the other end is opposed electrode 22a. It is wrapped around the outer surface of the arc tube. Further, one end of a lead wire 27 made of nickel is connected to the external lead 26 to which the trigger wire is connected, and the other end is fixed by welding to a terminal block 28 attached to the outer surface of the side portion of the reflecting mirror 24. Further, a base 29 to which an external lead led from the other electrode 22a of the arc tube is connected is fixed to the bottom of the reflecting mirror 24. In this way, a light source device is constructed in which a short arc metal halide lamp including an arc tube without an outer tube and a reflecting mirror are combined.

[0004]

However, when a start-up test was conducted by constructing an optical device using the ballast having the light source device and the high-voltage pulse generator, the start-up test showed that it did not start. Alternatively, the start of the start may be delayed and a lamp may be generated that causes a start failure. As a result of studying the cause of this, as shown in FIG. 2 (b), the trigger wire wound around the arc tube is loose without adhering to the outer wall of the arc tube, and a sufficient auxiliary discharge is generated by arc discharge between both electrodes. Because it is not.

This is because when an iron-based thin wire used for an inexpensive heating wire is used as the trigger wire, due to its characteristics, there is a variation in tightly adhering to the outer wall when winding it around the arc tube. This is because it often occurs and is transferred to the next step while being loosened. Further, when the lamp is repeatedly lit with the rated power after completion of the lamp, the trigger wire wound around the outer wall may be loosened due to heat generated from the arc tube as the lighting time elapses. For this reason, during manufacture, a lamp that is not sufficiently wound around the arc tube or a lamp that loosens due to a lighting test and whose starting is not reliable is readjusted by bringing them into close contact, and a starting test is performed to confirm lighting. As described above, the readjustment of the trigger line of the arc tube requires a lot of working time in manufacturing, and there is a problem that the yield is low. Further, it is possible to use a platinum wire having heat resistance and flexibility as a material of the trigger wire, but it is generally not popular because it is more expensive than an iron-based thin wire.

The present invention has been made in view of the above, and by improving the trigger wire serving as a starting auxiliary conductor provided on the outer wall of the arc tube, workability in manufacturing the arc tube using inexpensive parts is improved. It is an object of the present invention to provide a metal halide lamp which has a high yield, a good yield, a reliable start, and a good starting characteristic. In addition, it is possible to provide a lamp whose starting is surely prevented because the trigger wire is tightly wound around the arc tube and is not loosened or dropped for a long time. Further, it is possible to provide a lamp that can be used as a light source device for various optical devices such as a liquid crystal projector and can be reliably started regardless of the amount of light in the device.

[0007]

According to the present invention, a pair of electrodes are sealed at both ends of an arc tube, an arc length is set to 12 mm or less, and a metal halide is enclosed therein together with mercury and a rare gas. In a metal halide lamp which is activated by applying a high-voltage pulse to a trigger wire wound around the outer circumference of the arc tube, the trigger wire is preliminarily subjected to a refining treatment. The trigger wire is made of an alloy containing iron. Furthermore,
A light source device in which one end of the arc tube is fixed to a bottom of a bowl-shaped reflecting mirror is arranged in an optical device, and an illuminance at a position where the light source device is installed in the device is 10 lux or less. It is an optical device using the short arc metal halide lamp. Furthermore, the short arc metal halide lamp comprising a liquid crystal projector by arranging an optical lens and an optical system such as a liquid crystal panel on the front surface of a light source device in which one end of the arc tube is fixed to the bottom of a bowl-shaped reflecting mirror. It is the optical device used.

[0008]

With the above structure, since the trigger wire made of iron-based fine wire wound around the outer wall of the arc tube is annealed in advance, the flexibility is great and the winding work is easy, and the adhesion to the outer wall is good. Is. Further, even if a long time has passed, the arc tube is not loosened by the heat, and the starting can be performed easily and surely. Further, iron or its alloy wire can be used, which is inexpensive. Further, the light source device including the combination of the lamp and the reflecting mirror can be used for various optical devices, and the light source device can be reliably started even in a device with low illuminance.

[0009]

The present invention will be described below with reference to the embodiment shown in FIG. In the figure, reference numeral 1 is a quartz arc tube, and a pair of main electrodes 2a and 2b are sealed at both ends thereof, and arranged so that the distance between the electrodes is 5 mm. The central part of the tube has a diameter of 11.5 mm and a wall thickness of 1.0 mm, and the body of the spheroid, which has an internal volume of about 0.5 ml, has dysprosium iodide, neodymium iodide and iodide inside. Cesium weight ratio of 8: 2: 5, 0.5 mg each, buffer effect mercury 12 mg
And 1.5 × 10 ⁴ pascals of argon as a starting auxiliary gas are enclosed. A reflective / heat retaining film 3 made of a mixture of alumina and silica is applied to the outer peripheral surface of one electrode 2b of the arc tube 1.

At one end of the arc tube 1, the optical axis of the reflector 4 and the arc tube 1 are formed on the bottom of the bowl-shaped reflector 4 made of hard glass.
The tube axes of are fixed so that they match. The reflecting mirror has a parabolic shape with an effective diameter of 115 mm and a focal length of 16 mm, and its reflecting surface is a cold mirror surface 4a having a dielectric multilayer film formed by vacuum deposition. Further, a trigger wire 5 is arranged on the outer circumference of the arc tube, and the trigger wire is made of iron-based heat-resistant metal, and is a thin wire having a diameter of 0.25 to 0.3 mm, which is previously annealed at about 1000 ° C. And molded. Furthermore, one end of the trigger wire 5 is connected to the external lead 6 led out from the one electrode 2b, and the other end is wound around the outer surface of the arc tube of the counter electrode 2a in a ring shape. The outer lead 6 made of molybdenum and the one end of the lead wire 7 made of nickel and having a diameter of 0.6 mm are connected with the nickel sleeve 8
It is integrally connected to the inside by resistance welding. The other end is fixed by welding to the terminal block 9 attached to the outer surface of the side of the reflecting mirror 4. A base 10 to which an external lead led out from the other electrode 2a of the arc tube 1 is connected to the bottom of the reflecting mirror 4 is fixed via an inorganic adhesive 11.

In this way, a light source device is constructed in which a short arc metal halide lamp having a rated power of 150 W, which is an arc tube without an outer tube, and a reflecting mirror are combined,
When it was mounted on a liquid crystal projector device and started by applying a high voltage pulse of about 15 KV using an electronic ballast, it was about 5
It became a stable lighting state in minutes. At this time, the optical characteristics are the average color rendering index Ra85, the (x, y) chromaticity is (0.29,
0.32), the total luminous flux is 11,500 lm, and good color characteristics are recognized. Further, there is a feature that there is little unevenness in color and illuminance on the screen.

As described above, the trigger wire is disposed in close contact with the outer wall because when the fine wire of iron or iron alloy is used as the trigger wire without using an expensive platinum wire, the material is originally springy. Therefore, it is difficult to wrap it tightly and wraps it loosely, or it is far from the outer wall,
This is to prevent the start-up failure because it often deviates from the original winding position. In addition, even if the lamp is initially turned on, the trigger wire is gradually annealed due to heat generated from the lamp as time passes, and the trigger wire is loosened and detached from the outer wall, which may not be turned on at the next start. On the other hand, the pre-annealed iron wire has flexibility, is excellent in winding workability, and does not loosen because it has been annealed once.

Next, the experimental results will be described. Short arc metal halide lamp 1 configured as described above
00 lamps are configured as a light source device, and assuming the inside of the optical device, the first lighting and the second lighting are performed at an illuminance of 10 lux or less, and the lighting probability is investigated. All the lamps are lit within a predetermined time. did. On the other hand, when the same experiment as described above was performed for the conventional lamp using the non-annealed trigger wire, in the first time, three of 100 lamps had defects, and some lamps had a delayed starting time. Occurred. In the second lighting, 6 lamps became defective, and the number of lamps with a slow starting time increased compared to the first lighting.

As described above, since the trigger wire as the starting auxiliary conductor is preliminarily annealed with an inexpensive iron-based heat-resistant thin wire and used, a light source device that can be easily started even in a dark place where the illuminance is small such as in the device is obtained. It turned out to be obtained. Also, even if the stray light in the optical device is installed in the overhead projector whose stray light is about 10 lux, even if it is installed in the liquid crystal projector whose stray light in the device is about 1 lux, it can be reliably turned on once. I was able to confirm that it started. In the case of a lamp having an arc length of 12 mm or more, it is not necessary to use a trigger wire as a starting assisting means, and a high-voltage pulse generator can be surely started.

[0015]

As described above, the short arc metal halide lamp according to the present invention has a relatively simple structure, and the manufacturing process can be simplified by using an inexpensive arc tube material, and the lamp yield is good. Not only the workability is good, but the completed lamp can be easily and surely started from the start of lighting to the end of its life, and the starting characteristics are good. Further, there is an advantage that it can be used as a light source device of various optical devices such as a liquid crystal projector and can be reliably started regardless of the amount of light in the device.

[Brief description of drawings]

FIG. 1 is a schematic side view of a light source device configured by combining a short arc metal halide lamp and a reflecting mirror according to the present invention.

FIG. 2 is a schematic side view and a side view of essential parts of a light source device configured by combining a conventional short arc metal halide lamp and a reflecting mirror.

[Explanation of symbols]

 1 Quartz arc tube 2a, 2b Main electrode 3 Reflective / heat insulating film 4 Reflector 5 Trigger wire 6 External lead 7 Nickel lead wire 8 Nickel sleeve 9 Terminal block 10 Base 11 Inorganic adhesive

Claims (4)

[Claims] 1. A pair of electrodes are sealed at both ends of an arc tube, an arc length is set to 12 mm or less, and a metal halide is enclosed together with mercury and a rare gas, and a trigger wire is provided on the outer circumference of the arc tube. A short arc metal halide lamp, characterized in that the trigger wire is preliminarily subjected to a refining treatment in a metal halide lamp which is activated by winding a wire and applying a high-voltage pulse. 2. The short arc metal halide lamp according to claim 1, wherein the trigger wire is formed of an alloy containing iron. 3. A light source device in which one end of the arc tube is fixed to the bottom of a bowl-shaped reflecting mirror is arranged in an optical device, and the illuminance at a position where the light source device is installed in the device is 10 lux or less. An optical device using the short arc metal halide lamp according to any one of claims 1 and 2. 4. A liquid crystal projector is constructed by arranging an optical system such as an optical lens and a liquid crystal panel on the front surface of a light source device in which one end of the arc tube is fixed to the bottom of a bowl-shaped reflecting mirror. An optical device using the short arc metal halide lamp according to the item 2.