JPS61140051A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To prevent breakdown of outer tube due to breakdown of light emission tube by improving arrangement of two insulators for supporting the light emission tube against the outer tube. CONSTITUTION:Light emission tube 4 made of silicon glass is fixed with supporting boards 7, 8 at the sealing sections 5, 6 and secured to supporting wires 9, 10. Heat-resistant tubular insulators 11, 12 made of alumina ceramic or silicon glass are brought near to the surface of light emission tube 4 through the supporting wires 9, 10 and fixed at such position as to be separated by 180 deg. with respect to the axis of light emission tube 4. The light emission tube 4 is fixed such that the face of sealing section 5 will cross approximately in perpendicular with a plane including the insulators 11, 12. Consequently, even upon breakdown of light emission tube 4 during operation, the chips dispersed from the sealing sections 5, 6 of light emission tube 4 will collide at first against the insulators 11, 12 thereby impact is weakened resulting in prevention of breakdown of outer tube 1.

Description

[Detailed description of the invention] Industrial applications The present invention relates to metal vapor discharge lamps.

Conventional technology In metal vapor discharge lamps, such as mercury lamps and metal halide lamps, where the arc tube installed inside the outer bulb is composed of a quartz glass tube, the arc tube sometimes breaks during lamp operation, and the impact This causes an accident in which the outer tube is also damaged and glass pieces are scattered around.

Regarding the causes of such destruction of the arc tube, the destruction of the arc tube that occurs when the lamp is lit horizontally or tilted is caused by the arc inside the arc tube, the bluish-white color, and the damage to the arc tube. The upper part of the tube wall is heated excessively, and the quartz glass in this part gradually crystallizes, decreasing its mechanical strength and increasing its strength along the boundary with the part where no crystallization occurs. This occurs because internal stress in the quartz glass is generated and grows until the quartz glass can no longer withstand the vapor pressure within the arc tube and the internal stress. On the other hand, when the lamp is operated in a vertical position, such a phenomenon can occur. Breakage of the arc tube in the vertical position is due to manufacturing variations, and the internal pressure resistance of the arc tube is relatively low. This occurs when the internal pressure resistance of the arc tube becomes lower than the vapor pressure inside the tube before the lamp reaches the end of its life due to ponding due to a decrease in internal pressure resistance during the movement. Conceivable.

As a countermeasure against this phenomenon, it is possible to install a tube made of metal mesh or heat-resistant glass around the arc tube in the outer bulb to prevent the impact from the quartz glass fragments from reaching the outer bulb when the arc tube breaks. However, in both cases, the light absorption is large and the luminous flux value is significantly reduced, and the emission of photoelectrons from metals and moisture from heat-resistant glass adversely affect the lamp's movement characteristics. I'm sorry.

Problems to be Solved by the Invention The present invention has been made to solve these problems, and is designed to minimize the negative effects on the luminous flux value and travel characteristics, and to prevent the arc tube from breaking during operation, especially in a vertical position. To provide a metal vapor discharge lamp in which the outer bulb is not damaged by the impact when the metal vapor discharge lamp is heated.

Means to Solve the Problem The inventor conducted various simulation experiments and found that the destruction of the arc tube in a lamp operating in a vertical position is caused by the crimped surface peeling off starting from the sealed portion of the arc tube. The present invention was developed based on the discovery that the fragments of the arc tube are mainly scattered in a direction substantially perpendicular to the surface of the arc tube sealing portion when the arc tube is broken.

In the metal vapor discharge lamp of the present invention, two insulators that also serve to support the arc tube inside the outer bulb are arranged close to the surface of the arc tube so that they are approximately 18o0 apart from each other with respect to the axis of the arc tube, and The arc tube is mounted in such a position that the surface of its sealed portion is substantially perpendicular to the surface containing the two insulators.

With this structure, even if the arc tube breaks, the fragments that fly from around the sealing part of the arc tube will hit the insulator, which will reduce the impact force and prevent major damage to the outer bulb. It can be prevented.

Examples below/Unexploded ""-5"JiC'I/Ic・p A,
A description will be given with reference to the drawings, taking a single-id lamp as an example.

In FIG. 1, a stem 2 is sealed at one end of an outer tube 1, and a base 3 is fixed thereto.

The arc tube 4 made of quartz glass or the like has a sealing part 5,
Support plates 7 and 8 are attached to 6 and fixed to support lines 9 and 10. Tubular heat-resistant insulators 11 and 12 made of alumina ceramic, quartz glass, etc. are brought close to the surface of the arc tube 4 by support lines 9 and 1o, and are positioned approximately 180 degrees from each other with respect to the axis of the arc tube 4. installed.

As shown in FIG. 2, the arc tube 4 is mounted in such a manner that the surface of its sealing portion 5 is substantially perpendicular to the plane containing the insulators 11 and 12. Reference numeral 13 indicates a starting resistor, and 14 indicates a bimetal switch.

In FIG. 1, the ends of the support wires 9, 1o are insulators 11.
They are inserted into only a small part of the ends of the arc tubes 12, but this is because in metal halide lamps in which an iodide such as scandium is sealed in the arc tube 4, metal parts are not inserted into the light emitting part of the arc tube 4. This is because it is preferable not to place them close to each other in terms of motion characteristics.In metal halide lamps and mercury lamps that do not have such concerns, the support wire is placed close to the arc tube 4 over almost the entire length, and a heat-resistant insulated tube is attached to it. It is better to cover it.

As configured as above, in the metal vapor discharge rung of the embodiment of the present invention, due to variations in the pressure bonding strength of the sealing parts 5 and 6 due to manufacturing of the arc tube 4, the internal pressure resistance strength of the arc tube is compared. Even if the arc tube 4 were to break due to a decrease in the normal internal pressure strength during the movement, there would be damage from the vicinity of the sealing part 6.6 of the arc tube 4 at the time of breakage. The flying debris first hits the insulators 11 and 12, so
The impact force is weakened, and it is possible to prevent the outer tube 1 from being seriously damaged. Furthermore, compared to a conventional structure in which the entire circumference of the arc tube 4 is covered with a wire mesh or a tube made of heat-resistant glass, less light is absorbed and there is no adverse effect on the movement characteristics.

Although a tubular insulator was used as the insulator in the above embodiment, it is also possible to use a rod-shaped insulator with hollow parts at both ends into which the ends of the support wires can be inserted, without making the entire insulator hollow. good.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention'/'i provides two insulators in close proximity to the surface of the arc tube and spaced approximately 1 angular relative to each other with respect to the axis of the arc tube.
They are placed at 8o0 positions, and the surface of the sealed portion of the arc tube is installed at a position that is almost perpendicular to the plane containing the two insulators, so even if the arc tube breaks, When the arc tube is broken, fragments flying from around the sealed part of the arc tube hit the insulator and the impact force is alleviated, which prevents accidents that would seriously damage the outer bulb, and protects the entire area around the arc tube. It is possible to provide a metal vapor discharge lamp that absorbs less light and has improved movement characteristics compared to conventional lamps that are covered with wire mesh or the like.

[Brief explanation of the drawing]

FIG. 1 is a front view of a metal halide lamp which is an embodiment of the present invention, and FIG. 2 is a perspective view showing the main parts thereof. 1... Outer tube, 4... Arc tube, 5. θ・
... Sealing part of arc tube, 7, 8 ... Support plate, 9.10 ... Support line, 11.12 ... °
“Insulator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 2
figure

Claims (1)

[Claims] An arc tube is provided within the outer envelope, and two insulators are disposed close to the surface of the arc tube and approximately 18 mm apart from each other with respect to the axis of the arc tube.
A metal vapor discharge lamp characterized in that the arc tubes are arranged at 0° positions, and the surfaces of the sealed portions of the arc tubes are mounted at positions substantially perpendicular to a plane containing the two insulators.