JPS639987Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a metal vapor discharge lamp that is started by bringing a nearby conductor into contact with the outer surface of an arc tube housed in an outer bulb and applying a starting voltage, which is a sinusoidal voltage and a peak voltage, to the arc tube. For example, high-pressure sodium lamps have extremely superior light efficiency compared to mercury lamps, but the starting voltage is high, so the starting means is complicated. The reason for this is that since it is not possible to use materials such as quartz glass for arc tube bulbs, bulbs made of translucent single crystals or polycrystals, such as alumina ceramic or sapphire, are used. Problems include the inability to place an auxiliary electrode inside the bulb, and the use of xenon gas to increase light efficiency, which requires a high starting voltage. Various improvements have been made in the past as means for lowering the above-mentioned starting voltage, but recently, a filament and a bimetal switch heated by the filament are housed together with the arc tube in the outer tube, and the filament and bimetal switch are are connected in series, and this series circuit is connected in parallel to the arc tube, and when the bimetallic switch is closed at room temperature during startup, electricity is applied to heat the filament, and this heat opens the bimetallic switch. A method is being adopted in which a high voltage pulse is applied to the arc tube due to the kick voltage at the time of opening, and this is superimposed on a sinusoidal voltage from an externally connected ballast, thereby lighting the bulb at a high starting voltage.
According to this method, the high voltage pulse generated from the bimetal switch is extremely high, depending on the lamp rating, so there is no need for a special high voltage pulse generation means in the ballast, and the ballast for mercury lamps can be used instead. There is. However, simply applying a high voltage pulse to the arc tube does not allow reliable starting, so for example, as shown in JP-A-50-153479, a nearby conductor is brought into contact with the outer surface of the arc tube. is brought close to one electrode and this adjacent conductor is kept at the same potential as the other electrode, thereby creating a rapid potential gradient between these adjacent conductors and the one electrode adjacent to this, facilitating starting. I'm trying to make it a reality. In this way, by combining the effect of the adjacent conductor and the application of the high voltage pulse described above, it becomes possible to use the lamp for lighting at a commercial voltage of 200V or less. However, if the proximal conductor remains close to the arc tube even while the lamp is lit, it will attract sodium ions in the arc tube and promote the reaction between alumina and sodium. This causes problems such as blackening of the alumina tube and, in the worst case, cracks. In order to avoid this, in the above-mentioned publication, the adjacent conductor is composed of a pair of bimetal pieces, and when the lamp is cooled down before starting, the bimetal piece is brought into contact with the arc tube, and during stable lighting, the bimetal piece receives the heat of the arc tube. Since the arc tube is curved, this bimetal piece is separated from the arc tube. However, since the adjacent conductor described in the above-mentioned publication is provided at only one location along the tube axis of the arc tube, a potential gradient occurs at only one location at the time of starting, and starting performance is not necessarily perfect. For this reason, it has been considered to separate the electrodes at opposing potentials from the adjacent conductor sequentially or continuously by forming the adjacent conductor in a long shape along the tube axis of the arc tube. If this is done, many potential gradients will be generated continuously, increasing the chances of starting, and even if a good potential gradient is not generated at one location, starting will be encouraged at other locations, ensuring a reliable start. I can do it. It is desirable for such a long proximity conductor to be close to or in contact with the arc tube when the temperature is low before starting, and to be separated from the arc tube during stable lighting.For this reason, each end of the proximity conductor is connected to a bimetallic piece to emit light. It has been proposed to attach it to a tube support member or a conductive member. However, if each end of the adjacent conductor is supported by a bimetal piece, not only will a large number of expensive bimetal pieces be used, but also the temperature distribution will actually vary in the tube axis direction inside the outer tube. Thermal responsiveness will not be the same, and the adjacent conductor will not reliably come into contact with and separate from the arc tube. On the other hand, if one end of the nearby conductor is supported by a bimetal piece and the other end is fixed to the arc tube support member by means such as welding, this fixed point will restrict the movement of the other end of the nearby conductor. There is a problem that obstructs the contact/separation operation. This idea was made based on these circumstances, and its purpose is to support the end of the proximate conductor on the base side of the outer tube with a bimetal, and to support the other end with a coil spring. Therefore, it is an object of the present invention to provide a metal vapor discharge lamp that is easy to assemble, enables cost reduction, and has good closeness of the adjacent conductor to the arc tube bulb. An embodiment of this invention will be described below with reference to FIGS. 1 to 8. The drawing shows a high-pressure sodium lamp rated at 400W, with reference numeral 1 indicating an outer tube, 2 a cap attached to one end of the outer tube 1, and 3 an eyelet terminal provided on the cap 2. A stem 5 is attached to the end of the neck portion 4 of the outer tube 1.
is sealed, and this stem 5 has an internal conductor 6.
a and 6b are sealed. One internal conductor 6a
is connected to the base 2, and the other internal conductor 6b is connected to the eyelet terminal 3. Each of these internal conductors 6a and 6b is provided with a conductive support 7 that also serves as a part of the arc tube support member.
a, 7b are welded together, and the support 7a, which is connected to the base 2 via the internal conductor 6a, extends inside the outer tube 1 toward the other end, and connects to the small diameter top portion 8 formed at the tip of the outer tube 1. It is landed via elastic plates 9, 9. Conductive holders 10, 10 are attached to these supports 7a, 7b, respectively.
In this case, one end of one holder 10 is electrically connected to the other support 7a, and the other end is supported by one support 7a via an insulating glass tube 11. A light emitting tube 12 is placed between the holders 10 and 10 so as to be positioned on the tube axis of the outer tube 1 along the vertical direction in the drawing. This arc tube 12 has an arc tube bulb 13 made of an alumina ceramic tube with an inner diameter of 8 mm and a total length of 114 mm, and caps 14 and 1 made of niobium, tantalum, etc.
4 is closed, and main electrodes 15a, 15b are attached to these caps 14, 14 so as to face each other. These main electrodes 15a, 15b are electrically connected to the supports 7a, 7b via holders 10, 10. In the arc tube bulb 13, a predetermined amount of mercury and sodium are filled as luminescent metals, and for example, as a starting rare gas.
It is filled with 300 torr of xenon gas. A proximity conductor 16 is provided on the outside of such an arc tube 12. The proximal conductor 16 is made of a difficult-to-melt metal such as tungsten, molybdenum, tantalum, etc., and has a long rod-like or foil-like shape, and in this embodiment, a molybdenum wire with a wire diameter of 0.5 mm is used. The proximity conductor 16 is disposed along the longitudinal direction of the arc tube 12 in contact with or very close to the outer surface of the arc tube bulb 13. And this proximity conductor 1
One end of 6 located on the base 2 side is close to the main electrode 15b located on the base 2 side, and the tip of a thermally responsive metal member, that is, a bimetal 17, is welded to this one end. The base end of this bimetal 17 is welded to a support 7a connected to the other main electrode 15a opposite to the main electrode 15b located on the base side. In addition, the above-mentioned nearby conductor 1
The other end of the support 7a located on the valve top side is supported by a coil spring 19 at a distal end portion of the support 7a, for example, a portion 18 disposed perpendicular to the tube axis of the outer tube 1. In this case, as shown in detail in FIG. 3, the coil spring 19 is positioned such that the axis of the coil spring 19 is along the extension line of the proximal conductor 16, and this coil spring 19 is located at the end of the proximal conductor 16. The portion may be integrally coiled, or may be a separate coil spring. And the coil spring 19 and the above part 18 of the support 7a
and are welded together. Furthermore, in the outer tube 1, an insulating base 20 is provided close to or inside the neck part 4, and is provided on the stem 5 via a fixing rod 21. A filament 22 serving as a body and a bimetal switch 23 heated by the filament 22 are provided. The above filament 22
As shown in FIGS. 4 and 5, for example, a large number of coil bodies 24 are arranged side by side along the tube axis direction, and these coil bodies 24 are connected in series to form a planar heating element. Each coil body 24... has a coil outer diameter of, for example, 1.5~
The coil length is approximately 25 mm. The coil bodies 24 are arranged with an interval of about 2 mm from each other. In order to arrange and configure each coil body 24 in this way, the base 2
0, and the coil bodies 24 are held by the anchor wires 25.
As shown in FIG. 5, the filament 22 has a gap l ₁ =5 to 10 in the radial direction from the arc tube 12.
The bimetal switch 23 is provided radially outward of the filament 22. The bimetal switch 23 has a bimetal piece 27 as a thermally responsive part fixed to the upper end of a conductive support rod 26 supported through the base 20, and a fixed contact rod 28 disposed apart from the support rod 26 with the bimetal piece 27 fixed thereto. Piece 27
Movable contact rod 2 made of tungsten or the like at the tip of
7a can be brought into contact and separated. The bimetal piece 27 is different from the filament _22.
It faces this filament 22 at a distance of approximately 10 mm, and is disposed on the outside of the filament 22, that is, between the filament 22 and the outer tube wall. Therefore, the bimetal switch 23 is the filament 22.
The arc tube 12, the filament 22, and the bimetal switch 23 are arranged in the radial direction perpendicular to the tube axis of the outer tube 1, which runs in the vertical direction in FIG. They are arranged in the following order. Further, the bimetal piece 27 of the bimetal switch 23 is adapted to come into contact with the inner wall surface of the outer tube 1, as shown in FIG. 5, when it is thermally deformed. That is, as will be described later, the bimetal piece 27 is thermally deformed by the heat from the filament 22 and the heat from the arc tube 12 and separates from the movable contact rod 28.
The amount of thermal deformation is regulated by contact with the inner wall surface of the outer tube 1. Further, one side surface of this bimetal piece 27, that is, the surface facing the inner wall surface of the outer tube 1, is formed into a rough surface 29 as shown in FIG. This rough surface 29 is a bimetal piece 27
The bimetallic piece 27 is formed by means such as sandblasting, de-honing, or chemical treatment, so that one side of the bimetallic piece 27 has a larger surface area than the other side. By electrically connecting one end of the filament 22 and the conductive support rod 26, the filament 22 and bimetal switch 23 can be
The arc tubes 12 are connected in series as also shown in FIG. connected in parallel to. The lamp having such a configuration is connected to a commercial power source via a ballast 30, as shown in FIG. The operation of such a lamp will be explained. Before starting, the inside of outer tube 1 is at room temperature, so
The proximal conductor 16 is in contact with the outer surface of the arc tube bulb 13, and the movable contact rod 27a of the bimetal piece 27 of the bimetal switch 23 is in contact with the fixed contact rod 28, so that the bimetal switch 23 is closed. When the lamp is connected to a commercial power source via a ballast as shown in FIG. 7, the filament 22 is energized and generates heat. Also. The proximal conductor 16 that is in contact with the outer surface of the arc tube bulb 13 is kept at the same potential as the main electrode 15a that is separated from the base 2 side.
Since the end portion of No. 6 on the base 2 side is close to the main electrode 15b on the base 2 side, a steep potential gradient is generated in the vicinity of the main electrode 15b. When the heat generated by the filament 22 grows and heats the bimetal switch 23, the bimetal switch 23 is opened and a high voltage pulse of several thousand volts is generated as a result of this opening operation. By being superimposed on the sinusoidal voltage of the commercial voltage, an extremely high starting voltage is applied between the opposing main electrodes 15a and 15b. At this time, since a large potential gradient is generated between the proximal conductor 16 and the main electrode 15b on the base side, starting is performed when the above-mentioned high voltage, a starting voltage of about 2000 to 4000 V, is applied. In other words, because the kick voltage of the bimetal switch 23 is used as the starting voltage and the nearby conductor 16 creates a potential gradient, even if the lamp is filled with xenon gas of 200 torr or more, it will not be stable for normal mercury lamps. By using a power supply, it is possible to light the lamp using a commercial power supply of 200V or less. Moreover, as the potential gradient is applied by the proximate conductor 16, the discharge progresses along the proximal conductor 16 at the time of starting, so that starting is performed more reliably. When the lighting of the lamp started in this way becomes stable, the temperature of the arc tube bulb 13 rises, and this heat heats the bimetal 17 connected to the adjacent conductor 16, so that the bimetal 17 is heated as shown in the imaginary line in Fig. 2. It is curved to Therefore, the adjacent conductor 16 is separated from the arc tube bulb 13, and sodium ions are no longer attracted to the adjacent conductor 16 and react with the alumina tube, preventing blackening and reducing the light emitted from the bulb 13. The adjacent conductor 16 itself will not be thermally deformed. Bimetal 17 like this
The other end of the proximal conductor 16, one end of which is separated from the arc tube 12 by
Since the coil spring 19 is supported through the coil spring 19, even if torsional stress is generated in the adjacent conductor 16, the coil spring 19
It is absorbed by the elastic deformation of the coil spring 19, and even if an axial extension stress occurs due to thermal expansion, it is absorbed by the axial deflection of the coil spring 19. That is, the adjacent conductor 1
The other end of the coil spring 19 can move freely within the range of elastic deformation of the coil spring 19, so when torsional stress or extension stress is applied, the coil spring 19 bends in response to this stress, so the proximal conductor 16 itself does not deform. It is. On the other hand, in the bimetal switch 23, since the bimetal piece 27 is provided directly opposite the planar filament 22, the bimetal switch 23 easily receives heat generated from the filament 22.
Thermal responsiveness is improved. After the bimetallic switch 23 is opened, since the bimetallic switch 23 is relatively close to the filament 22, the residual heat of the filament 22 maintains the thermally deformed posture, keeping the bimetallic switch 23 open. are doing. Therefore, the open state can be maintained until the arc tube 12 reaches a high temperature. Then, as the temperature of the arc tube 12 increases, the heat from the arc tube 12 is transferred to the filament 2.
Since the radiation is radiated to the bimetal switch 23 through the gap between the two coil bodies 24, the bimetal switch 23 can still maintain its open state. In addition, in this open state, the tip of the bimetal piece 27 is
As shown by the imaginary line in FIG. 5, it is in contact with the inner wall surface of the outer tube 1, and prevents the bimetal piece 27 from curving more than necessary. Then, when the lamp is turned off, arc tube 1
Since the heat dissipation from 2 is stopped, the bimetal switch 23 shifts to the closing operation. In this case, since the filament 22 is interposed between the bimetal switch 23 and the arc tube 12, the arc tube 12
Since the residual heat of the arc tube 12 is blocked by the filament 22, the rate at which the bimetal switch 23 receives the residual heat of the arc tube 12 is greatly reduced. Moreover, the bimetal piece 2 in the bimetal switch 23
7 is in contact with the inner wall surface of the outer tube 1, so the bimetal piece 2 is attached to the outer tube 1, which is normally cooled by the outside air.
As the heat of 7 is taken away, this movable piece 27
Since one side of is formed into a rough surface 29,
The surface facing away from the arc tube 12 is large and has good heat dissipation, so that the temperature of the bimetal piece 27 itself is quickly lowered. Furthermore, since the bimetal piece 27 is in contact with the inner wall surface of the outer tube 1, it is prevented from curving more than necessary, and the return distance from the fixed contact rod 28 is also restricted to a small value. For this reason, the return operation of the bimetal switch 23 is performed extremely quickly, and the time from when the light is turned off until the bimetal piece 27 comes into contact with the fixed contact rod 28, that is, the restart time, is shortened. It has been confirmed that the restart time of the above embodiments is shortened to 4 to 6 minutes. Furthermore, when the lamp is turned off in this manner, the bimetal 17 of the proximate conductor 16 also returns, so the proximal conductor 16 comes into contact with the outer surface of the light-emitting bulb 13. At this time, the coil spring 19 also elastically returns, so that the proximal conductor 1
6 will be reliably brought into close contact with the arc tube bulb 13, and since the discharge will proceed along the adjacent conductor, restart will be ensured. Next, the results of comparing the structure of the proximity conductor according to this embodiment with that of a conventional example and examining its effects will be explained. Table 1 shows a comparison in terms of ease of assembly and price, and Table 2 shows an investigation of the failure rate at lighting times of 100 hours and 1000 hours. Sample A: Both ends of the proximate conductor are supported by bimetal pieces (conventional example) Sample B: One end (base side) of the proximal conductor is supported by a bimetal piece, and the other end is attached to the support by welding ( Conventional example) Sample C: One end (base side) of a nearby conductor is supported by a bimetal piece, and the other end is supported by a coil spring on a support (this example) Each sample uses 100 lights and the average value is the average value. It has been determined by

【table】

[Table] From the above results, it is recognized that the support structure for the adjacent conductor according to the present example is superior to each of the conventional examples. In the above embodiments, a high-pressure sodium lamp has been described, but the present invention is not limited thereto, and can also be applied to, for example, a metal halide lamp. Further, the movable piece 27 of the bimetal switch 23 is not necessarily limited to one that comes into contact with the inner wall surface of the outer tube 1, and is not limited to one that has a rough surface 29 formed on one side. Even in the case of a filament, it is not limited to a structure in which a large number of coil bodies 24 are arranged side by side in a blind shape, but a planar heating element can be formed by, for example, bending a single coil into a W-shape. Moreover, it is not necessarily necessary to make it planar. Further, in the above embodiment, a filament 22 and a bimetal switch 23 which responds thermally by being heated by the filament 22 are housed in the outer tube 1.
Since the arc tube 12 is started using the high voltage pulse caused by the kick voltage generated when the ballast 30 opens, there is no need for any parts that generate an exceptionally high voltage pulse inside the ballast 30. Therefore, there is an advantage that a normal ballast for a mercury lamp can be used, but the present invention is not limited to accommodating the filament and bimetallic switch in the outer bulb 1 as described above. That is, as described above and as in the modified example shown as a circuit diagram in FIG. Even if the device 90 itself generates a starting voltage by superimposing a peak voltage such as a high frequency wave on a sinusoidal voltage, the implementation shown in FIGS. 1 to 8 can be implemented. The examples are not limited. The device described in detail above has a proximal conductor attached along the tube axis direction of the arc tube housed in an outer bulb having a cap at one end. The end close to the cap is connected via a bimetal to a conductive member having the same potential as the electrode that is spaced from the cap, and the end that is spaced from the cap is attached to the arc tube support member via a coil spring. Therefore, when the bimetal is turned on, it is bent by the heat of the arc tube, so the adjacent conductor is separated from the arc tube, thereby preventing blackening and cracking of the arc tube, and preventing radiation from the arc tube. Light occlusion is also prevented. Moreover, since bimetal is used only at one end of the adjacent conductor, the amount of expensive bimetal used is small, and since the other end of the adjacent conductor is supported by a coil spring, the curvature of the bimetal causes torsional stress on the adjacent conductor. Even if the adjacent conductor acts, it can be absorbed by the elasticity of the coil spring, and even if the adjacent conductor thermally expands, it can be absorbed by the elasticity of the coil spring, so that no undue stress is applied to the adjacent conductor, and no deformation occurs. In particular, the elasticity of the coil spring absorbs torsional stress and elongation stress due to thermal expansion, so even if the bimetal bends and returns many times, the adjacent conductor will return reliably, and will be in close contact with the arc tube. The intended purpose of providing the conductor can be fully achieved. In addition, coil springs are easy to handle, and there is no need to pay attention to directionality during welding, etc., so they can be assembled easily and have the advantage of being inexpensive.

[Brief explanation of drawings]

Figures 1 to 8 show one embodiment of this invention, with Figure 1 being a front view of the entire high-pressure sodium lamp, Figure 2 being a sectional view showing the adjacent conductor and bimetal, and Figure 3 being an enlarged view of the main parts. Figure 4 is a wavefront diagram of the main parts seen from the back side of Figure 1, Figure 5 is a view taken along the V-V line in Figure 4, and Figure 6 is an enlarged top view of the bimetal switch. 7 is a lighting circuit diagram, FIG. 8 is a starting voltage characteristic diagram, and FIG. 9 is a lighting circuit diagram showing a modified example. 1... Outer tube, 12... Arc tube, 13... Arc tube bulb, 15a, 15b... Electrode, 16... Proximity conductor, 19... Coil spring, 22... Filament, 23... Bimetal switch.

Claims (1)

[Scope of utility model registration request] An arc tube made of a translucent single crystal or polycrystal, which has electrodes at both ends and seals a luminescent metal and a rare gas inside, is housed in an outer bulb having a cap at one end, and the outer tube is A proximal conductor is attached to the surface along the tube axis, and when starting, a starting voltage in which a peak voltage is superimposed on a sinusoidal voltage is applied to the arc tube to light it, and the proximal conductor is attached to the cap. The end close to the side is connected via a bimetal to a conductive member having the same potential as the electrode spaced apart from the base side, and the end spaced apart from the base side is attached to the arc tube support member via a coil spring. A metal vapor discharge lamp characterized by: