JPS62122049A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To surely prevent excessive kick voltage from being generated during restarting, thereby preventing and trouble such as burning, insulation destruction, etc. of a stabilizer, by letting the recovery of a neighboring portion via a heat responsive means be earlier than the closing recovery of a bimetal switch. CONSTITUTION:When a lamp is turned off, a bimetal 26 for separating a neighboring conductor and the bimetal plate 21 of a bimetal switch 19 gradually recover. In this case, the thickness t1 of the bimetal 26 for separating the neighboring conductor is made to be thinner than the thickness of the bimetal plate 21 of the bimetal switch 19, so that the cooling speed of the bimetal 26 is faster than that of the bimetal plate 21. Therefore, the bimetal 26 for separating the neighboring conductor surely recover first, and when the bimetal switch 19 is closed after the recovery of the bimetal plate 21 in a lamp cooling process, a neighboring conductor 24 surely comes close to a luminous tube 4. In this way, any trouble such as generating an excessive kick voltage, by a current flow through a resistance heater body 18, in the condition that neighboring effect by the neighboring conductor 24 is not established yet, resulting in opening of the bimetal switch 19, is surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a metal vapor discharge lamp with improved restart characteristics.

(Prior Art) Generally, high-pressure sodium lamps have higher luminous efficiency than high-pressure mercury lamps and the like, so they are used in a wide range of fields as various light sources.

However, high-pressure sodium lamps have a higher starting voltage than the above-mentioned high-pressure mercury lamps, so they cannot be lit with a ballast for high-pressure mercury lamps, and they require an expensive dedicated ballast.

In order to improve this, a proximal conductor is provided close to the arc tube, and this proximal conductor is connected to have the same polarity as one electrode inside the arc tube, and a normally closed resistance heating element such as a filament is connected inside the outer bulb. A structure has been proposed in which a starting voltage generating circuit formed by connecting bimetal switches (first bimetal switches) in series is connected and housed in parallel with the arc tube.

According to this, when the rung is started, electricity is passed through the resistance heating element through the first bimetallic switch to generate heat, and this heat opens the first bimetallic switch, resulting in the stabilization that occurs at this moment. A high kick voltage based on the inductance of the tube is applied between the adjacent conductor and the other electrode to generate a large ζ-position gradient between the adjacent conductors and the other electrode, thereby causing an arc in the arc tube. It causes electric discharge.

According to this device, it can be lit even if the ballast used in high-pressure mercury lamps is used as a ballast, and it has the advantage of being inexpensive.

By the way, in devices equipped with the above-mentioned starting device, sodium ions in the arc tube are attracted to the nearby conductor during lighting and react with the materials that make up the arc tube, causing early blackening of the arc tube. There is.

To prevent this, conventionally, in order to electrically disconnect the adjacent conductor from one electrode after lighting, the adjacent conductor is placed in the circuit that electrically connects the adjacent conductor and one electrode. A bimetal switch ('#, 2 bimetal switch) was provided for separation.

(Problem to be Solved by the Invention) However, in the above-mentioned rung, since the first and second bimetal switches are housed in the outer tube, it is necessary to turn off the light while the light is on. If the engine was restarted before it had completely cooled down, a kick pressure much higher than the design value would occur, resulting in burnout of the ballast9, short circuit at the socket, and insulation breakdown.

When the cause of this was investigated, it was found that during the rung cooling process after the light is turned off, the first bimetal switch sometimes recovers faster than the second bimetal switch, resulting in the above-mentioned problem. In other words, the kick voltage generated at the moment the first bimetal switch is opened has the potential to reach a considerably high voltage;
Since this kick voltage generates a discharge between the adjacent conductor and the other electrode, a voltage higher than the discharge starting voltage between the adjacent conductor and the other electrode is not generated.

When starting from room temperature, power supply starts with both the first bimetal switch and the second bimetal switch closed, so first the first bimetal switch opens due to the heat from the resistance heating element. and discharge begins,
Thereafter, the second bimetallic switch is opened by receiving heat from the arc tube and instantly disconnects the adjacent conductor from one electrode. Therefore, in this case, a kick voltage higher than the discharge starting voltage between the adjacent conductor and the other electrode is not generated.

However, at the time of restart, the first bimetal switch and the second bimetal switch, which were in an open state due to heat from the arc tube, are turned off and the first bimetal switch switches to the second bimetal switch. When the bimetal switch returns first, the resistance heating element is energized in this state, so the first bimetal switch is opened without the second bimetal switch returning. In this case, since the adjacent conductor is still disconnected from one electrode, it can perform its original function, thus requiring a firing voltage between the two electrodes in the arc tube, which results in an extremely high kick. A voltage will be generated.

This caused problems such as ballast burnout and insulation breakdown.

An object of the present invention is to provide a metal vapor discharge lamp that can reliably prevent the generation of an excessive kick voltage at the time of restart, and can prevent problems such as ballast burnout and dielectric breakdown.

[Structure of the Invention] (Means for Solving Problems) The present invention provides an arc tube housing a pair of electrodes, an outer tube housing the arc tube, and an arc tube housed within the outer tube in parallel with the arc tube. a series circuit consisting of a resistive heating element connected to the resistive heating element and a bimetallic switch opened by heat from the resistive heating element; a connected proximity conductor; and a thermally responsive actuator for separating the adjacent portion of the adjacent conductor from the arc tube when the arc tube is turned on and returning the adjacent portion when the lamp is turned off, the thermally responsive means causing the adjacent portion The bimetal switch is characterized in that the return of the bimetal switch is faster than the return of the bimetal switch to the closed state.

(Function) According to the present invention, during lighting, the portion of the proximal conductor that is close to the arc tube is separated from the arc tube by the thermally responsive operating means, so that sodium ions and the like in the arc tube are not attracted. Prevents early darkening. When the light goes out, the nearby conductor returns to its original state faster than the bimetal switch and comes close to the arc tube, so when restarting, a discharge is reliably started between the nearby part and the other electrode, resulting in a high kick voltage. will not occur. In this case, even if the bimetal switch returns and generates a kick voltage when the adjacent conductor does not return completely but returns halfway, the adjacent conductor is connected to one electrode via the thermally responsive actuating means. Since the electrical connection state is maintained, it functions as a proximal conductor even during a state of return, and there is no need to worry about generating an excessive kick voltage as in the conventional case. This increases the permissible range of gender and provides greater freedom in design.

(Embodiment of the Invention) The present invention will be described below based on an embodiment shown in the drawings.

This embodiment is applied to a 360W high-pressure sodium lamp, and in the figure, 1 is an outer tube, 2 is a stem, and 3 is a cap. An arc tube 4 is housed within the outer tube J. This arc tube 4 is made of a translucent alumina ceramic material, and end caps 5.6 made of niobium are sealed at both ends, and electrodes 7, 8 are attached to these end caps, respectively.
is installed. The arc tube 4 is attached via holders 11 and 12 to support wires 9 and 10, which serve both as support and supply. The support wires 9 and 10 are welded to lead-in wires 13 and 14 sealed to the stem 2, respectively, and the tip of one of the support wires is attached to a leaf spring 15.
, 15 at the top of the outer tube 1. One electrode 2 of the arc tube 4 is connected to one support wire 9 via a holder 11, and the other electrode 8 is connected to the other support 10 wire via a holder 12. Note that the other holder 12 is electrically insulated from one support wire 9 by an insulating tube 16.

There is mercury in the above luminous tube 4) IJ Kumto 300
Torr of xenon gas is sealed.

A starting voltage generation circuit 17 is built in the outer tube 1.
This starting voltage generating circuit 17 includes a resistance heating element 18 made of a tungsten filament and a normally closed bimetal switch 1.
9 are connected in series. This starting voltage generating circuit 17 is connected between the support wires 9 and 10 and in parallel with the arc tube 4.

Note that 20 is a substrate that supports these resistance heating element 18 and bimetal switch 19, and this substrate 20 is made of an electrically insulating material.

The resistance heating element 18 made of the filament is mounted on this substrate 2.
0 in a meandering manner. Further, the bimetal switch 19 includes a bimetal plate 21 and this bimetal plate 2.
This bimetal plate 21 is mounted on the base 20 in close proximity to the resistance heating element 18, and the bimetal plate 21 is made up of a movable contact 22 and a fixed contact 23 attached to the tip of the resistance heating element 18. It is configured to receive heat and heat from the arc tube 4.

Reference numeral 24 denotes a proximity conductor, which is formed from a wire made of a high melting point metal material such as molybdenum or tantalum, and is provided close to the outer peripheral surface of the arc tube 4 and along the longitudinal direction of the arc tube 4. It is being One end of the proximity conductor 24 is bent into a crank shape, and its tip is supported by a shaft support member 25 attached to one of the support wires 9 so as to be rotatable and slidable in the axial direction. Also,
The other end of the proximate conductor 24 is welded to the tip of a thermally responsive actuator for disconnecting the proximal conductor, such as a bimetal piece 26, which is connected to one of the support wires 9. Since the adjacent conductor 24 is connected to the one T-wire 9 via the shaft supporting member 25 and the adjacent conductor separating bimetal piece 26, it is always electrically connected to the one electrode 7. It is connected. Further, the proximity conductor 24 is
When the bimetal piece 26 is deformed by the heat from the arc tube 4, it rotates around the shaft support member 25 and separates from the arc tube 4.

The bimetal piece 26 for separating the adjacent conductor and the bimetal plate 21 of the bimetal switch 19 are made of a highly heat-resistant bimetal, such as TNY bimetal manufactured by Toshiba Corporation (high expansion coefficient side material: N1-Mn-Fe alloy, low expansion coefficient side). Material: N1-p alloy, maximum operating temperature 450℃
) or HTY bimetal (high expansion coefficient side material: N1-
It is formed from a Cr-F alloy, a low expansion coefficient ECR-F alloy, and a maximum operating temperature of 550°C. Then, the thickness of the bimetal plate 21 of the bimetal switch 19 is 1. It is formed very thinly, and the ratio t1/11 of these thicknesses is tl/12≦048, and these thicknesses! tell is o,
os am or more and 0.2 ho or less.

One embodiment of the present invention constructed as described above is connected to a ballast for a mercury lamp and lit as shown in FIG. Then, in a low temperature state, a bimetal piece 26 for disconnecting the adjacent conductor
Both the bimetal plate 21 of the bimetal switch 19 and the bimetal switch 19 are in the restored state, the proximal conductor 24 is close to the arc tube 4, and the bimetal switch 19 is closed. Then, when power supply is started to start the engine from this state, a current flows through the resistance heating element 18 and generates heat, and this heat deforms the bimetal plate 21 and opens the bimetal switch 19.

At this moment, a kick voltage is generated by the inductance of the ballast A, and this kick voltage is applied between the proximal conductor 24 and the other electrode 8, causing a discharge in the space between them within the luminous mass.

In this case, the proximal conductor 24 is placed close to the arc tube 4, and the distance from the other electrode 8 is small, so the discharge starting voltage between them is relatively low, so the kick voltage is the withstand voltage of the ballast A, etc. Below, it is about 2500V, for example. The discharge between the adjacent conductor 24 and the other electrode 8 causes ionization of the substance enclosed within the arc tube 4, causing arc discharge between the electrodes 2.8 and starting lighting.

After lighting, the adjacent conductor separating bimetal piece 26 is deformed by the heat from the arc tube 4 and moves the adjacent conductor 24 away from the arc tube 4. Further, the bimetal plate 21d of the bimetal switch 19 receives heat from the arc tube 4 to maintain the deformed state, and the bimetal switch 19 maintains the open state.

When the rung is turned off, the entire rung gradually cools down, and correspondingly, the bimetal plate 21 of the bimetal switch 19 and the bimetal 26 for separating adjacent conductors gradually return to their original positions. In this case, since the thickness t 1' of the bimetal piece 26 for separating adjacent conductors is formed thinner than the thickness tl of the bimetal plate 21 of the bimetal switch 19, the heat capacity relative to the surface area is smaller than that of the bimetal plate 21, and therefore the bimetal The cooling rate is faster than that of the plate 21. Therefore, the bimetal piece 26 for separating the adjacent conductor will surely return first. Therefore, when the bimetal plate 21 returns and the bimetal switch 19 is closed during the cooling process of the lamp, the adjacent conductor 24 is always connected to the arc tube 4.
close to. Therefore, as in the conventional case, it is possible to ensure that problems such as the occurrence of an excessive kick voltage due to the resistance heating element 18 being energized and the bimetal switch 19 being opened while the proximity effect due to the proximity conductor 24 is not yet obtained can be avoided. can be prevented.

Furthermore, since the proximate conductor 24 is always connected to the elongated pole 7 through the bimetal piece 26 and the support wire 9, the proximal conductor 24 can produce a proximity effect even while returning to its predetermined position. can. That is, when the proximal conductor 24 is returned halfway, the other electrode 8
The starting performance is poor due to the long distance between the bimetallic switch 19, but when the bimetallic switch 19 is closed and then opened, a kick voltage is definitely applied between the adjacent conductor 24 and the other electrode 8, so that no discharge occurs. Start. The kick voltage at this time is slightly higher than when the adjacent conductor 24 is completely restored, but it does not reach an excessive voltage that would cause burnout or dielectric breakdown of the ballast.

From this, close conductor cut il! Although the bimetallic piece 26 needs to return faster than the bimetallic switch 19, some variation is allowed within this range. Therefore, strict thermal responsiveness is no longer required, the degree of freedom in design is increased, and manufacturing is facilitated.

On the other hand, in a conventional device including a first and second bimetal switch, no potential is applied to the adjacent conductor unless the second bimetal switch is closed.
It is necessary to restore the second bimetal switch completely and before the first bimetal switch. Therefore, the thermal response accuracy of the second bimetal switch must be strictly selected, contact adjustment is also required, and manufacturing conditions and adjustment conditions become stricter.

Since the order of return of the bimetal 26 for disconnecting the adjacent conductor and the bimetal plate 21 of the bimetal switch 19 is determined by making their thicknesses different, the order of return is reliably regulated. . That is, in order to regulate the order of these returns, it is sufficient to vary their cooling rates, so it is also possible to vary their cooling rates by, for example, varying their placement locations. However, when these parts are housed in the outer tube 1, the light from the arc tube 4 must not be blocked and other conditions require that their placement is practically limited to the vicinity of the neck of the outer tube 1. Due to these limitations, slightly different placement locations will not make a large difference in the cooling rate, and since lamp usage conditions vary widely, the cooling conditions for the entire rung will not be constant. , it is difficult to reliably regulate the return order simply by selecting the placement location.

However, as in this embodiment, the bimetal piece 26 for separating adjacent conductors and the bimetal plate 2 of the bimetal switch 19
By varying the thickness of 1, it is possible to create a clear difference in the cooling rate, and even if there is a slight change in the cooling conditions, the return order can be reliably regulated.

In order to confirm such an effect, a large number of prototypes were manufactured with various thicknesses tls and tl of the bimetallic piece 26 for separating the adjacent conductor of the lamp of the above-mentioned embodiment and the bimetallic plate 21 of the guimetal switch 19. The lamp was turned on for a certain period of time, then turned off, and during the cooling process, the power supply was restarted and restarted, and the kick voltage at the time of restart was investigated. 1st
The table shows an example of the experimental results, and this example was obtained when the lamp was lit bare at room temperature.

Table 1 As is clear from the results, if the thickness tl of the bimetal piece 26 for separating adjacent conductors is made thinner than the thickness tl of the bimetal plate 21 of the bimetal switch 19, the bimetal switch 19 will open after returning. When the kick voltage is generated, the proximal conductor 24 is already completely close to the arc tube 4, so the generated kick voltage is stabilized at 2500V.

On the other hand, when the thicknesses of jlsj2 are made equal, the kick voltage increases to 3000V, and this 3000V is the limit of the withstand voltage of a ballast, etc. When 11 becomes thicker than tl, the kick voltage becomes 3000 V or more, which exceeds the withstand voltage limit of a stabilizer or the like.

Therefore, in order to prevent the kick voltage from exceeding 3000V, it is necessary to make at least tl smaller than tl.

In addition, as a result of experiments with various lighting conditions for such a lamp, it was found that the cooling rate was slowest when the lamp was housed in a sealed floodlight, and the bimetal of the bimetal 26 for separating the adjacent conductor and the bimetal switch 19 was the lowest. It has been found that there is little difference in the return speed of the plate 21. The experimental results in this case are shown in Table 2.

Table 2 As is clear from the results, in order to keep the kick voltage below 3000V even when lighting is in a sealed type floodlight with the worst conditions, t! The ratio tt/lz of t2 and t2 should be 0.8 or less.

In addition, as a result of considering the thicknesses of the bimetal plate 21 for separating the adjacent conductors and the bimetal plate 21 of the bimetal switch 19 from other points, it was found that these thicknesses were 0.05 mm.
It has been found that if there is no groove in the gap, permanent deformation occurs during use, making it impractical.

Furthermore, when we investigated the relationship between the thickness of the bimetal plate 21 of the bimetal switch 19 and the time it takes for it to recover and restart, we obtained the results shown in FIG. 4. In addition, the solid line in FIG. 4 shows the case of naked lighting, and the broken line shows the case of being housed in a closed type floodlight. Since the restart time of this type of lamp usually needs to be 10 minutes or less, the thickness t2 of the bimetal plate 21 is at least 0.2 m'x.
It is necessary to keep it below t.

If all of the above conditions are satisfied, the generation of excessive kick voltage can be reliably prevented under any usage conditions, and the restart time can be made equal to or less than that of conventional products. be.

Note that the present invention is not limited to the above embodiment.

(9) If the bimetal for disconnecting the adjacent conductor and the bimetal switch can be arranged freely, such as when the outer tube has a special shape, etc., the return order of the bimetal switch may be regulated by changing their arrangement locations. . Alternatively, the bimetal for separating adjacent conductors may be formed to have a rough surface or a black surface to increase heat dissipation, increase the cooling rate, and regulate the return order. Further, these configurations may be used together.

Therefore, the thickness of the bimetal plate of the bimetal switch and the bimetal for separating adjacent conductors may not necessarily be within the above range depending on the case.

Furthermore, the present invention is applicable not only to high-pressure sodium lamps but also to other metal vapor discharge lamps such as metal halide lamps.

[Effects of the Invention] As explained above, according to the present invention, when the light is turned off, the adjacent part of the adjacent conductor returns to its original position before the bimetal switch, so when restarting, the adjacent part of the adjacent conductor and the other electrode are reliably connected. The discharge starts, thereby preventing excessive kick voltage from being generated. Moreover, since the adjacent conductor is always electrically connected to one of the electrodes, even if the adjacent conductor does not return completely, it still has its original function. Even if there are slight variations in performance, it is possible to start without generating particularly excessive kick voltage. Therefore, there is no need to strictly set the temperature of the thermally responsive actuating means, which allows for greater flexibility in design and manufacturing, making it easier to manufacture.

Further, since the thermally responsive actuating means does not require any contacts, troublesome efforts such as adjusting the contacts are not required. For this reason, generation of excessive kick voltage can be prevented, and burnout and dielectric breakdown of the ballast can be prevented.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a longitudinal cross-sectional view, FIG. 2 is a view taken along the arrow line ``--'' in FIG. 1, and FIG. 3 is a circuit diagram.
FIG. 4 is a characteristic diagram showing the relationship between the bimetal plate and restart time. , 1... Outer tube, 4... Arc tube, 7.8... Electrode,
17... Starting voltage generation circuit, 18... Resistance heating element,
19... Pimetal switch, 21... Bimetal plate, 24... Proximity conductor, 26... Bimetal for disconnecting proximate conductor (thermal response operating means), A... Ballast. Applicant: Toshiba Corporation Fig. 3 Bimetal plate n Gansaitz (mm) Fig. 4

Claims (1)

[Claims] An arc tube that houses a pair of electrodes, an outer tube that houses the arc tube, a resistance heating element that is housed in the outer tube and is connected in parallel with the arc tube, and is released by the heat from the resistance heating element. a series circuit consisting of a bimetallic switch, a proximate conductor having a portion proximate to the arc tube and connected to the same polarity as the one electrode, and a proximate conductor having a portion proximate to the arc tube connected to the bimetal switch; A metal vapor characterized in that it is equipped with a thermally responsive operating means that is moved away from the arc tube at times and returns when the light is turned off, and that the returning action of the adjacent portion by the thermally responsive means is faster than the closing action of the bimetallic switch. discharge lamp.