JPH09115485A - High pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of pulse voltage when a luminous tube disables to start by connecting a series circuit which consists of a specific starter, a thermally reacting switch and a temperature fuse in parallel to the luminous tube and connecting a discharge gap in parallel to a glow starter for the starter. SOLUTION: A luminous tube which has a pair of electrodes at both ends and luminous material filled inside and a starter 2 to apply pulse voltage between both electrodes for the luminous tube 1 are installed in an outer tube 6 which is evacuated inside. The starter 2 is formed with a series circuit which consists of a glow starter 2a and a heating resistor 2b. The series circuit which has the starter, a thermally reacting switch 3 and a temperature fuse 4 is connected in parallel to the luminous tube 1 and the glow starter 2a is connected in parallel to a discharge gap 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a high pressure discharge lamp having an arc tube and a starter for generating a pulse voltage for starting built in an outer tube.

[0002]

2. Description of the Related Art One construction of a first high pressure discharge lamp which has been generally used conventionally as a starting circuit for a high pressure discharge lamp having a built-in starter such as a high pressure sodium lamp. An example is shown in FIG. In FIG. 5, a starter 2 composed of a series circuit of a heat responsive switch 2a and a heating resistor 2b is connected in parallel with the arc tube 1. The proximity conductor 7 is provided so as to come into contact with the outer surface of the arc tube 1 via the heat responsive switch 8 and is housed in the outer tube 6 for the purpose of assisting the starting. The first high-pressure discharge lamp having such a configuration is connected to the AC power source 1 via the ballast 9.
When connected to 0, the thermoresponsive switch 2a repeats the opening / closing operation. Since the current flowing through the ballast 9 is cut off at the moment when the thermal switch is opened, a pulse voltage is generated across the ballast 9. This pulse voltage is superimposed on the power supply voltage and applied to the arc tube 1, so that discharge of the arc tube 1 starts. During stable lighting of the high-pressure discharge lamp, the heat-responsive switch 2a and the heat-responsive switch 8 are caused by the radiation heat from the arc tube 1.
Are kept open.

However, the above-mentioned conventional first high-pressure discharge lamp has the following problems. When the starting voltage of the arc tube 1 significantly increases at the end of the life of the high-pressure discharge lamp, or when the connection to the arc tube 1 is cut off for some reason such as a mechanical shock from the outside, the arc tube 1
Does not start, and the voltage of the power supply 10 continues to be applied to the starter 2,
Pulse voltage continues to be generated. If the power switch is left turned on in such a state, the life of the ballast 9 may be shortened due to continuous application of the pulse voltage, or the insulation of the wiring between the ballast 9 and the high pressure discharge lamp may be deteriorated. .

As a means for solving such a problem, for example, a second method disclosed in Japanese Patent Application Laid-Open No. 7-105913.
High pressure discharge lamps are known. FIG. 6 shows the configuration. In FIG. 6, the starting device 2 and the first
The series circuit composed of the thermal response switch 3 of is connected,
Further, a series circuit composed of the heating resistor 18 and the heat responsive switch 19 is connected in parallel with them. The heating resistor 18 is arranged close to the first thermoresponsive switch 3. In such a configuration, if the arc tube 1 does not light up even though pulses are generated by the ballast 9 and the starter 2, this high-voltage pulse continues to be generated, but at the same time, the heating resistor 18 generates heat. The heat causes the thermal switch 3 to open. As a result, the starter 2 is disconnected from the lighting circuit, and the generation of pulse voltage is stopped.
However, since the second high-pressure discharge lamp does not cause the starter 2 itself to be in an inoperable state,
When the application of the power supply voltage to the high-pressure discharge lamp is stopped, the original state is restored, and the generation of the pulse voltage for a certain period is repeated every time the power is turned on again.

Further, in addition to the above-mentioned problem when the arc tube 1 cannot be started, at the end of the life of the high pressure discharge lamp, the hermeticity of the sealed portion of the arc tube 1 is lowered, and the arc tube 1 is used for starting. In some cases, the rare gas may flow out into the vacuum outer tube 6. When the rare gas inside the arc tube 1 flows into the outer tube 6, the pressure of the rare gas inside the arc tube 1 decreases, and in addition, convection and heat conduction by the rare gas in the outer tube 6 causes the arc tube to discharge. The temperature of 1 decreases. Therefore, the lamp voltage (operating voltage of the arc tube 1) becomes lower than that during normal operation. Arc tube 1
The lamp voltage further decreases as the outflow of noble gas from the lamp progresses. When the lamp voltage decreases, the lamp current increases, and the increase in the lamp current causes the temperature of the ballast 9 to rise excessively. When the power switch is turned off in such a state, the high pressure discharge lamp is cooled, and then the power switch is turned on again, the arc tube 1 starts discharging again. If the high-pressure discharge lamp is left in such a state, the temperature of the wire winding of the ballast 9 rises and the life of the ballast 9 is shortened.

As a solution to this problem, for example,
A third high-pressure discharge lamp described in Japanese Patent Laid-Open No. 63177 is known. FIG. 7 shows the configuration. In FIG. 7, the starter 2 formed by a series circuit of the thermal response switch 2a and the heating resistor 2b is used when the overcurrent flows.
The current fuse element 4 for interrupting the circuit is connected in series. Further, the terminal 20 on the side of the current fuse element 4 of the starter 2 is arranged in the vicinity of the conductor 21 of the opposite potential. In such a configuration, when the starting rare gas leaks from the arc tube 1 and flows out into the outer tube 6, when the pulse voltage is generated in the ballast 9 by the operation of the starter 2,
Before the discharge of the arc tube 1 is started, a discharge is generated between the terminal 20 of the starter 2 and the conductor 21 of the opposite potential adjacent thereto. As a result, the short-circuit current of the ballast 9 flows through the current fuse element 4, the current fuse element 4 is cut off, and the starter 2 becomes inoperable. Therefore, the arc tube 1 does not discharge after that.

However, in this method, particularly when the pressure of the rare gas flowing into the outer tube 6 is extremely low immediately after the outflow of the rare gas due to a decrease in the airtightness of the sealed portion of the arc tube 1 or the like, particularly When a glow starter that can obtain only a relatively low pulse voltage is used as the starter 2,
There remains a problem that the discharge in the outer tube cannot be reliably generated at a predetermined position.

The present invention has been made to solve the two different problems at the same time as described above, and when the arc tube cannot be started for some reason or when the arc tube sealing portion is deteriorated. In both cases when the starting gas flows out into the outer bulb, the starter is permanently inoperable by melting a part of the starter circuit to prevent the generation of pulse voltage. It is an object of the present invention to provide a high-pressure discharge lamp with high efficiency.

[0009]

In order to achieve the above object, a high pressure discharge lamp of the present invention comprises a light emitting tube having a pair of electrodes at both ends and a light emitting substance enclosed therein, and a space between both electrodes of the light emitting tube. A high-pressure discharge lamp having a starter for applying a pulse voltage to the inside of an outer tube whose inside is evacuated, wherein the starter is composed of a series circuit of a glow starter and a heating resistor. A series circuit of a thermoresponsive switch and a thermal fuse element is connected in parallel with the arc tube, and a discharge gap is connected in parallel with the glow starter.

In the above structure, it is preferable that the temperature fuse element is provided in the vicinity of the heating resistor of the starter. Further, in the above structure, it is preferable that the discharge gap has a pair of electrodes formed on a ceramic substrate.

In the above structure, at least one of the pair of electrodes of the discharge gap preferably contains an electron emitting substance. Further, in the above structure, the heating resistor is preferably a ceramic heater.

In the above structure, it is preferable that the heating resistor has a flat plate shape, and the thermal fuse element and the discharge gap are integrated with the heating resistor. Further, in the above-mentioned configuration, it is preferable that the thermal fuse element is disposed on a side of the heating resistor opposite to the arc tube.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A high pressure discharge lamp of the present invention comprises a light emitting tube having a pair of electrodes at both ends and a light emitting substance sealed therein, and a starter for applying a pulse voltage between both electrodes of the light emitting tube. And are installed in an outer tube whose inside is evacuated, and the starter is composed of a series circuit of a glow starter and a heating resistor, and a series circuit of the starter, a thermal switch and a temperature fuse element is connected in parallel with the arc tube. However, the discharge gap is connected in parallel to the glow starter. Therefore, if the high-pressure discharge lamp becomes inoperable for some reason, voltage is continuously applied to the starter composed of the glow starter and the heating resistor, and the current limited by the heating resistor continues to flow intermittently. The self-heating due to the current causes the temperature of the heating resistor to rise. Then, the thermal fuse element arranged in the vicinity of the heating resistor is blown when the temperature exceeds the melting temperature due to heating by the heating resistor.

Further, when the rare gas for starting the arc tube flows into the outer tube due to a decrease in the airtightness of the arc tube sealing portion, a discharge occurs in the discharge gap, and the current limited by the heating resistor is discharged. Flowing through the gap to the heating resistor, the temperature of the heating resistor rises, and when the temperature rises above the melting temperature of the thermal fuse element, the thermal fuse element melts.

When the thermal fuse element is blown, no more current can flow in the starter circuit, so that in either case the starter is permanently inoperable and after that the power supply is turned on again. However, no pulse voltage is generated.

An embodiment of the high pressure discharge lamp of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a schematic diagram showing a circuit configuration of an embodiment of a high pressure discharge lamp of the present invention, and FIG. 2 is a perspective view showing a configuration of a ceramic substrate on which a pair of electrodes forming a discharge gap 5 are arranged. 3 is a perspective view showing a unit of component parts including a thermal fuse element 4 and a ceramic substrate, and FIG. 4 is an enlarged view of a main part showing a component arrangement of the high pressure discharge lamp of the present invention.

As shown in FIG. 1, the high-pressure discharge lamp of the present invention is, for example, a sodium lamp having a pair of electrodes at both ends, and a rare gas such as xenon is enclosed therein together with sodium and mercury. A series circuit including an arc tube 1, a starter 2 connected in parallel to the arc tube 1, a first thermal response switch 3 and a temperature fuse element 4, a discharge gap 5, and a second thermal response switch 8 Through arc tube 1
A proximity conductor 7 for assisting the starting, which is arranged so as to contact the outer surface of the arc tube 1 and is connected to one electrode of the arc tube 1. Each of these components is arranged in an outer tube 6 whose interior is maintained in a high vacuum, and is connected to a ballast 9 and an AC power supply 10.

The starter 2 comprises a series circuit of a glow starter 2a and a heating resistor 2b for limiting the current flowing through the glow starter 2a. The first thermoresponsive switch 3 is for opening the circuit by the radiant heat from the arc tube 1 and shutting off the starter 2 during stable lighting of the high pressure discharge lamp. The thermal fuse element 4 is arranged in the vicinity of the heating resistor 2b, is heated by the self-heating of the heating resistor 2b, and is blown at a melting temperature or higher. The melting temperature of the thermal fuse element 4 is set higher than the temperature inside the outer tube 6 during stable lighting of the high pressure discharge lamp. The discharge gap 5 is connected in parallel to the series body composed of the glow starter 2a and the first thermoresponsive switch 3. The second heat-responsive switch 8 is for preventing the potential from being applied to the adjacent conductor 7 by opening the circuit due to radiant heat from the arc tube 1 during stable lighting of the high pressure discharge lamp. The second heat-responsive switch 8 is provided by the first heat-responsive switch 3 to ensure lighting when the high-pressure discharge lamp is restarted, that is, when the current to the high-pressure discharge lamp is cut off and turned on again. Is set so that the recovery time is short.

It is not always necessary to configure the circuit as shown in FIG.
It suffices to satisfy the condition that they are connected in parallel with a and in series with the series body of the heating resistor 2b and the thermal fuse element 4. For example, the first thermoresponsive switch 3 may be connected to any part of the series body including the glow starter 2a, the heating resistor 2b, and the temperature fuse element 4.

Next, an example of the structure of the discharge gap 5 is shown in FIG. In FIG. 2, the electrodes 5a and 5b are formed by baking tungsten powder on a ceramic substrate. Further, the electrodes 5a and 5b have terminals 11 and 12
Is attached. With such a configuration, the distance between the electrodes 5a and 5b of the discharge gap 5 can be kept constant.

As the heating resistor 2b shown in FIG. 1, an ordinary carbon film resistor may be used, or a flat ceramic heater may be used. In the latter case, as shown in FIG. 3, a required number of terminals can be attached to the flat plate-shaped ceramic heater which is the heating resistor 2b, and the discharge gap 5 shown in FIG. 2 can be integrally attached to form a unit. . As a result, the distance from the heating resistor 2b to the temperature fuse element 4 can be easily kept constant, and the component arrangement can be made compact. In FIG. 3, the terminals of the heating resistor 4 are 13 and 14, one electrode 5a of the discharge gap 5 is connected to the terminal 13, and the other electrode 5b of the discharge gap 5 is connected to the terminal 16, The fuse element 4 is connected to the terminals 14 and 15. Furthermore terminal 1
5 and 16 are connected to the same potential as both ends of the arc tube 1 in FIG. The terminal 17 is a mounting terminal for holding the entire unit at an appropriate position in the outer tube 6 of the high pressure discharge lamp, and is electrically non-conductive.

FIG. 4 shows specific mounting positions of the arc tube 1 and the thermal fuse element 4. As shown in FIG. 4, by installing the thermal fuse element 4 on the side opposite to the arc tube 1 with respect to the flat plate-shaped heating resistor 2b, the radiant heat of the arc tube 1 at the time of normal lighting directly causes the thermal fuse 4 to flow. Can be prevented from being irradiated. Therefore, it is possible to prevent thermal deterioration of the temperature fuse element 4 during lighting of the high pressure discharge lamp.

The high-pressure discharge lamp (high-pressure sodium lamp) configured as described above is connected to the power source 10 via the ballast 9.
When the voltage is applied, the glow starter 2a of the starter 2 starts the opening / closing operation, and a pulse voltage is generated between the terminals of the ballast 9. When the discharge of the arc tube 1 is started by the pulse voltage, the arc tube voltage decreases, so that the glow starter 2a stops its operation and the current flowing through the series circuit of the starter 2 also stops.

When the arc tube 1 operates normally, the time from application of the power supply voltage to the start of discharge of the arc tube 1 is several seconds at the longest. Therefore, even if it is heated by the heating resistor 2b during this period, the temperature fuse element 4
Does not reach the melting temperature. After that, when the temperature of the arc tube 1 rises, the heat of the arc tube 1 causes the first thermoresponsive switch 3 to open. Therefore, during stable lighting of the high pressure discharge lamp, the circuit of the starter 2 is maintained in a disconnected state.

On the other hand, at the end of the life of the high pressure discharge lamp, the starting voltage of the arc tube 1 remarkably rises, and a part of the current supply line to the arc tube 1 is cut off by a mechanical shock from the outside. As a result, when the arc tube 1 becomes incapable of starting, the arc tube 1 does not start discharging even if the power supply voltage is applied. At this time, the glow starter 2a continues to open and close, current continues to flow intermittently in the circuit of the starter 2, and the temperature of the heating resistor 2b rises. As a result, the temperature fuse element 4 is heated, and when the melting temperature thereof is exceeded, it is blown. As a result, the circuit of the starter 2 is permanently cut off, and thereafter, even if the high-voltage discharge lamp is left with the power supply voltage applied, or if the power supply voltage is repeatedly turned on, a pulse is generated. No voltage is generated and it is in a very safe state.

Further, at the end of the life of the high pressure discharge lamp or the like, when the starting rare gas in the arc tube 1 flows out into the vacuum outer tube 6 due to a decrease in the airtightness of the sealing portion of the arc tube 1,
Due to the presence of the rare gas, a discharge occurs between the electrodes 5a and 5b of the discharge gap 5 due to the pulse voltage at the start of the high pressure discharge lamp. When a discharge is generated in the discharge gap 5, a current limited by the resistance heating 4 flows through the discharge gap 5 to the heating resistor 2b, the temperature of the heating resistor 2b rises, and the temperature fuse element 4 melts at its melting temperature. If it becomes the above, it will fuse. If the thermal fuse element 4 is blown, no more current can flow in the circuit of the starter 2, so that the starter 2 is permanently inoperative and the high-pressure discharge lamp does not start. Therefore, it is possible to prevent a phenomenon in which the high-pressure discharge lamp operates in a state where the lamp voltage is low and the temperature of the ballast 9 excessively rises due to an increase in the lamp current.

[0027]

Next, specific examples of the present invention will be described. A 220 W high-pressure sodium lamp having the circuit configuration shown in FIG. 1 was prototyped. The arc tube 1 had an outer diameter of 9 mm and an electrode distance of 58 mm, and was filled with xenon as a starting rare gas at a pressure of about 27 kPa. The heating resistor 2b connected in series to the glow starter 2a has a side of 25 mm.
Ceramic heaters having square resistances of about 150Ω and 700Ω at room temperature and at a saturation temperature of about 750 ° C. were used. Further, as the temperature fuse element 4,
As shown in FIG. 3, a silver brazing wire having a diameter of 0.6 mm and a melting temperature of about 600 ° C. was attached at a position 3 mm away from the surface of the ceramic heater. As one electrode 5a of the discharge gap 5, a mixed oxide of barium, calcium, and yttrium, which is an electron emissive material, is applied and baked, and the distance between the electrode 5a and the electrode 5b is set to 3 mm, as shown in FIG. I installed it.

The high-pressure sodium lamp manufactured in this way is passed through a ballast for high-pressure mercury lamp of 250 W to 200 V.
When it was connected to the AC power source, the arc tube 1 started normally and went into a stable state through the process described above. Next, in order to perform an experiment in a state where the arc tube 1 cannot be started, after turning off the high-pressure discharge lamp and cooling it, the outer tube 6 is kept inside the outer tube 6 without destroying it by using a laser beam. The current supply line to the arc tube 1 was cut to make the arc tube 1 unstartable. When the power supply voltage was applied in this state, the current continued to flow in the circuit of the starter 2, the temperature of the ceramic heater as the heating resistor 2b rapidly rose, and the thermal fuse element 4 was blown after several tens of seconds. As a result, the circuit of the starter 2 was cut off, and the generation of the pulse voltage from the ballast 9 was stopped.

Further, since the hermeticity of the sealed portion of the arc tube 1 is lowered, a part of xenon as a rare gas for starting flows out from the arc tube 1 into the outer tube 6, so that the arc tube is realized. A lamp for experiment in which a pseudo arc tube whose xenon filling pressure was changed was held in the outer tube 6 together with 1 was made, and after the completion of the lamp, a hole was formed in the tube wall of the pseudo arc tube by the above-mentioned method with a laser. Xenon was allowed to flow into the outer tube 6.
When the power supply voltage is applied in that state, under the condition that the calculated xenon pressure in the outer tube 6 is 10 Pa or more, discharge occurs in the discharge gap 5 without starting discharge of the arc tube 1, and the temperature fuse element 4 is melted. did.

[0030]

As described above, according to the high pressure discharge lamp of the present invention, a pulse voltage is applied between both electrodes of a light emitting tube having a pair of electrodes at both ends and a light emitting substance enclosed therein. The starter for applying the voltage is installed in the outer tube whose inside is evacuated, and the starter is composed of a series circuit of a glow starter and a heating resistor, and a series circuit of the starter, the thermal response switch and the temperature fuse element. Since the discharge tube was connected in parallel with the arc tube and the discharge gap was connected in parallel with the glow starter, at the end of the life of the high-pressure discharge lamp, the starting voltage of the arc tube rose significantly and light was emitted due to mechanical shock from the outside. If the arc tube becomes unstartable due to a part of the current supply line to the tube being cut off, the glow starter will continue to open and close, and current will intermittently flow in the starter circuit. Continue heating resistor The temperature rises. As a result, the thermal fuse element is heated, and blows when it exceeds the melting temperature. As a result, the circuit of the starter is permanently cut off.After that, even if the high-voltage discharge lamp is left with the power supply voltage applied, or if the power supply voltage is repeatedly turned on, the pulse voltage Therefore, it is possible to provide a very safe high pressure discharge lamp.

On the other hand, when the starting rare gas in the arc tube flows out into the vacuum outer tube due to a decrease in the airtightness of the sealed portion of the arc tube, a pulse is generated at the time of starting the high pressure discharge lamp due to the presence of the rare gas. The voltage causes a discharge between the electrodes in the discharge gap. When discharge occurs in the discharge gap, a current limited by resistance heating flows through the discharge gap to the heating resistor,
When the temperature of the heating resistor rises and the temperature fuse element becomes higher than its melting temperature, it blows. If the thermal fuse element is blown, no more current can flow in the circuit of the starter, so that the starter is permanently inoperable and the restart of the high-pressure discharge lamp can be prevented. Therefore,
The high-pressure discharge lamp does not operate in the state where the lamp voltage is low, and it is possible to prevent the excessive temperature rise of the ballast due to the increase of the lamp current.

Further, by providing the temperature fuse element in the vicinity of the heating resistor of the starter, the heat generated by the heating resistor can be reliably transmitted to the temperature fuse element, and the starter of the starter in a state where the arc tube cannot be started. The energization time to the circuit can be shortened. Further, by forming the discharge gap by forming a pair of electrodes on the ceramic substrate,
A small gap spacing can be easily obtained. Also,
By including an electron emissive substance in at least one of the pair of electrodes in the discharge gap, the discharge in the discharge gap can be made more reliable.
Further, by using a ceramic heater as the heating resistor, the heating resistor can be formed in any shape. Furthermore, by making the heating resistor a flat plate shape and integrating the temperature fuse element and the discharge gap with the heating resistor, it is possible to easily keep the distance from the heating resistor to the temperature fuse element constant and to arrange the parts. Can be made compact. Further, by disposing the temperature fuse element on the opposite side of the heating resistor from the light emitting tube, it is possible to prevent the radiant heat of the light emitting tube from being directly applied to the temperature fuse when the high pressure discharge lamp is normally lit. It is possible to prevent thermal deterioration of the temperature fuse element during lighting of the high pressure discharge lamp.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a circuit configuration of an embodiment of a high pressure discharge lamp of the present invention.

FIG. 2 is a perspective view showing a structure of a ceramic substrate on which a pair of electrodes forming a discharge gap 5 are arranged.

FIG. 3 is a perspective view showing a unit of component parts including a temperature fuse element 4 and a ceramic substrate.

FIG. 4 is an enlarged view of essential parts showing the arrangement of parts of the high pressure discharge lamp of the present invention.

FIG. 5 is a schematic diagram showing a circuit configuration of a conventional first high pressure discharge lamp.

FIG. 6 is a schematic diagram showing a circuit configuration of a conventional second high pressure discharge lamp.

FIG. 7 is a schematic diagram showing a circuit configuration of a third conventional high pressure discharge lamp.

[Explanation of symbols]

 1: arc tube 2: starter 2a: glow starter 2b: heating resistor 3: first thermal response switch 4: thermal fuse element 5: discharge gap 5a: one electrode of discharge gap 5b: other electrode of discharge gap 6: Outer tube 9: Ballast 10: AC power supply

Claims (7)

[Claims] 1. An arc tube having a pair of electrodes at both ends and having a light emitting substance enclosed therein, and a starter for applying a pulse voltage between both electrodes of the arc tube are provided with a vacuum inside. A high pressure discharge lamp installed in a tube, wherein the starter is composed of a series circuit of a glow starter and a heating resistor, and the series circuit of the starter, a thermal switch and a temperature fuse element is connected in parallel with the arc tube. And a high-pressure discharge lamp in which a discharge gap is connected in parallel with the glow starter. 2. The high pressure discharge lamp according to claim 1, wherein the temperature fuse element is provided in the vicinity of a heating resistor of the starter. 3. The high pressure discharge lamp according to claim 1, wherein the discharge gap is formed by forming a pair of electrodes on a ceramic substrate. 4. Of the pair of electrodes of the discharge gap,
At least one electrode contains an electron emitting substance.
A high pressure discharge lamp as described. 5. The high pressure discharge lamp according to claim 1, wherein the heating resistor is a ceramic heater. 6. The high pressure discharge lamp according to claim 1, wherein the heating resistor has a flat plate shape, and a temperature fuse element and a discharge gap are integrated with the heating resistor. 7. The high pressure discharge lamp according to claim 6, wherein the thermal fuse element is arranged on the side of the heating resistor opposite to the light emitting tube.