JPH0973881A - High pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp which stops generation of pulse voltages if an emission tube cannot be started to operate or if a rare gas for starting the emission tube leaks out of an outer tube because of decrease in the airtightness of the sealed part of the emission tube, etc. SOLUTION: A series circuit of a starter 2 comprising a series circuit of a glow starter 2a and a heating resistor 2b, a first heat-reacting switch 3, and a current fuse element 4 is connected in parallel with an emission tube 1, and a discharge gap 5 is connected in parallel with the starter 2 or with a series circuit of the starter 2 and the first heat-reacting switch 3. When the glow starter 2a is heated by the heating resistor 2b, the glow starter 2a is closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure discharge lamp.

[0002]

2. Description of the Related Art Conventionally, for example, in a high pressure discharge lamp such as a high pressure sodium lamp, a starting rare gas such as xenon gas is filled in the arc tube and the filling pressure is increased. Improves efficiency. The structure of a general conventional high pressure discharge lamp is shown in FIG. As shown in FIG. 7, since the high-voltage discharge lamp has a high starting voltage, a starter 2 composed of a series circuit of a heat-responsive switch 2a such as a bimetal switch and a resistance heating element 2b for heating is arranged in parallel with the arc tube 1. It is connected and housed in the outer tube 8. In the starter 2, the resistance heating element 2b heats the heat-responsive switch 2a due to red heat, and the heat-responsive switch 2a is heated.
The current flowing through the ballast 9 is suddenly cut off by the opening of the switch to generate a pulse voltage.

The above-mentioned conventional high-pressure discharge lamp has the following two problems. First of all, when the starting voltage of the arc tube 1 significantly increases at the end of the life of the discharge lamp, or when the connection to the arc tube 1 is cut off for some reason such as mechanical shock from the outside, the arc tube 1 Does not start, the voltage of the power supply 10 continues to be applied to the starter 2, and the pulse voltage continues to be generated. If the power switch is left turned on in this state, pulse voltage continues to occur.

Secondly, in addition to the problem when the arc tube 1 cannot be started, at the end of the life of the discharge lamp, etc., the arc tube 1
In some cases, the airtightness of the sealed portion is deteriorated and the starting rare gas in the arc tube 1 flows out into the vacuum outer tube 8.
When the rare gas inside the arc tube 1 flows into the outer tube 8, the pressure of the rare gas inside the arc tube 1 is reduced, and in addition, the outer tube 8
The temperature of the arc tube 1 decreases due to convection and heat conduction by the rare gas inside. Therefore, the lamp voltage (the operating voltage of the arc tube 1) becomes lower than that in the normal operation, and the lamp current increases. An increase in lamp current causes an excessive rise in temperature of the ballast 9. Therefore, if left in this state, the ballast 9
There is a possibility that the service life of the ballast 9 may be shortened due to the temperature rise of the winding wire.

As a solution to this problem, for example, the method described in Japanese Patent Laid-Open No. 3-63177 is known. FIG. 8 shows the structure of another conventional high pressure discharge lamp using the method. In FIG. 8, a starter 2 composed of a series circuit of a heat-responsive switch 2a and a heating resistor 2b,
A current fuse element 4 for disconnecting the circuit of the starter 2 when an overcurrent flows is connected in series. In addition, the terminal 19 on the side of the current fuse element 4 of the starter 2 is arranged so as to be close to the dielectric body 20 having the opposite potential. In such a structure, when the starting rare gas leaks from the arc tube 1 and flows into the outer tube 8, when the pulse voltage is generated in the ballast 9 by the operation of the starter 2, the discharge of the arc tube 1 is started. Before, the discharge occurs between the terminal 19 of the starter 2 and the dielectric 20 of opposite potential in the vicinity thereof. 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, according to this method, immediately after the outflow of the rare gas due to a decrease in the airtightness of the sealing portion of the arc tube 1 or the like, the pressure of the rare gas flowing into the outer tube 8 is extremely low. In particular, when a glow starter that can obtain only a relatively low pulse voltage is used as the starter 2, there is a problem that the discharge in the outer tube cannot be reliably generated at a predetermined position.

The present invention has been made in order to solve the above two different problems at the same time. When the arc tube is in a non-startable state for some reason, and the airtightness of the arc tube sealing portion is improved. An object of the present invention is to provide a highly safe high-pressure discharge lamp in which a pulse voltage is not generated in both cases when a rare gas for starting flows out into the outer tube due to a decrease.

[0008]

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. And a starter for applying a pulse voltage to the inside of the outer tube whose inside is evacuated, the starter being composed of a series circuit of a glow starter and a resistance heating element, the starter, normally closed A heat-actuated switch and a current fuse element in series are connected in parallel with the arc tube, and
A discharge gap means is connected in parallel to the starter or a series body of the starter and the heat-responsive switch, and the glow starter is always closed by heat from the resistance heating element when the arc tube does not start. It is provided at the position where
The discharge gap means is arranged so as to blow the current fuse element through the discharge gap means when the starting rare gas flows into the outer tube from the arc tube.

In the above structure, it is preferable that the discharge gap means has a pair of electrodes formed on a ceramic substrate. Further, one of the electrodes of the discharge gap means is preferably a tungsten filament connected in series with the starter. Further, it is preferable that the tungsten filament further has a function of the current fuse element. Further, it is preferable that at least one of the electrodes of the discharge gap means contains an electron emitting substance. The resistance heating element of the starter is preferably a ceramic heater. Further, it is preferable that the resistance heating element of the starter has a flat plate shape, and the current fuse element and the discharge gap means are integrated on the surface of the resistance heating element.

[0010]

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. Is installed in an outer tube whose inside is evacuated, and the starter is composed of a series circuit of a glow starter and a resistance heating element, and a series circuit of the starter, a normally closed thermal response switch and a current fuse element is used. The discharge gap means is connected in parallel with the arc tube, the starter is connected with the discharge gap means in parallel, or the discharge gap means is connected in parallel with the series circuit of the starter and the thermal response switch. With this configuration, when the arc tube cannot be started for some reason, voltage is continuously applied to the starter composed of the series circuit of the glow starter and the resistance heating element, the glow starter is heated by the resistance heating element, and the glow starter is heated. The contact of is closed. Therefore, there is no change in the current flowing through the ballast, and the generation of pulse voltage is stopped. In addition, when a rare gas for starting the arc tube flows into the outer tube due to a decrease in the airtightness of the arc tube sealing part, a discharge occurs in the discharge gap, and the short-circuit current of the ballast passes through the discharge gap and the current fuse element. The current fuse element is blown. When the current fuse element is blown, no current flows in the starter circuit, and after that, no pulse voltage is generated even if the power is turned on again.

[0011]

Embodiment 1 Hereinafter, a first embodiment of the high pressure discharge lamp of the present invention will be described with reference to FIGS. 1 to 3. FIG.
Is a schematic diagram showing a circuit configuration of a first embodiment of a high pressure discharge lamp of the present invention, FIG. 2 is a perspective view showing a configuration of a ceramic substrate on which electrodes forming a discharge gap 5 are arranged, and FIG. It is a principal part enlarged view which shows the component arrangement of the high pressure discharge lamp of 1st Example. In the first embodiment, the case where the high pressure discharge lamp is a high pressure sodium lamp will be described.

As shown in FIG. 1, the high-pressure discharge lamp of the first embodiment has an arc tube 1 having a pair of electrodes at both ends, in which a rare gas such as xenon is contained together with sodium and mercury. A series circuit composed of a starter 2, a first thermoresponsive switch 3 and a current fuse element 4 connected in parallel to the arc tube 1, a discharge gap 5 connected in parallel to the starter 2, And a proximity conductor 6 for assisting the starting, which is arranged in contact with the outer surface and is connected to one electrode of the arc tube 1 through the second heat-responsive switch 7. Each of these components is arranged in an outer tube 8 whose inside is maintained in a high vacuum, and is connected to a ballast 9 and an AC power supply 10.

The starter 2 comprises a glow starter 2a and a series circuit of a resistance heating element 2b for limiting the current flowing through the glow starter 2a. The first heat-responsive switch 3 is for opening the circuit of the starter 2 by the radiation heat from the arc tube 1 during the stable lighting of the discharge lamp, and for disconnecting the circuit of the starter 2. The current fuse element 4 is configured to be blown out instantly when a current significantly larger than the current value determined by the resistance heating element 2b flows. The second heat-responsive switch 7 is provided for the arc tube 1 during stable lighting of the discharge lamp.
This is for preventing an electric potential from being applied to the adjacent conductor 6 by opening the circuit due to radiant heat from the. The second heat-responsive switch 7 has a recovery time longer than that of the first heat-responsive switch 3 in order to ensure lighting when the lamp is restarted, that is, when the current to the lamp is cut off and then turned on again. It is set to be short.

It is not always necessary to connect the first heat-responsive switch 3 to the position shown in FIG. 1, but to connect it to an appropriate position such as between the starter 2 and the current fuse element 4 to start the starter 2.
And the discharge gap 5 in the series circuit of the first thermal switch 3
May be connected in parallel.

Next, FIG. 2 shows an arrangement example of electrodes forming the discharge gap 5. The discharge gap 5 is formed by baking the electrodes on the ceramic substrate. Note that 11 and 1
Reference numerals 2 are terminals of the electrodes 5a and 5b of the discharge gap 5, respectively.

A starter 2 having a circuit configuration shown in FIG. 1, a first
FIG. 3 shows a specific arrangement example of the heat-actuated switch 3, the current fuse element 4, and the discharge gap 5. In FIG. 3, the glow starter 2a is provided so as to contact the resistance heating element 2b. The first thermoresponsive switch 3 is arranged above the glow starter 2a so that it is less likely to receive heat from the resistance heating element 2b. First thermal switch 3
A current fuse element 4 and a discharge gap 5 are provided between the and the glow starter 2a.

When the power supply voltage 10 is applied to the high-pressure discharge lamp (high-pressure sodium lamp) configured as described above via the ballast 9, the glow starter 2a of the starter 2 starts the opening / closing operation, and the ballast 9 of the ballast 9 is started. A pulse voltage is generated between the terminals. At this time, the glow starter 2a that constitutes the starter 2
The current flowing in the series circuit of the resistance heating element 2b is determined by the impedance of the ballast 9 and the resistance value of the resistance heating element 2b. Since the fusing current of the current fuse element 4 is set sufficiently higher than the current flowing through the starter 2, the current fuse element 4 will not be blown by this current. 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 the resistance heating element 2b heats the glow starter 2a during this period.
Does not reach the closed circuit temperature. On the other hand, at the end of the lamp life, the starting voltage of the arc tube 1 remarkably rises, or a part of the current supply line to the arc tube 1 is cut off by a mechanical shock from the outside. In the case where the electric power supply voltage is applied, the arc tube 1 does not start to discharge when the engine cannot be started. At this time, the glow starter 2a continues to open and close, and current continues to flow intermittently in the series circuit of the starter 2, the temperature of the resistance heating element 2b rises, and the glow starter 2a is heated. When the closing temperature of the contacts attached to the glow starter 2a is exceeded, the glow starter 2a
Always closes. As a result, there is no sudden change in the current flowing through the ballast 9, and the generation of pulse voltage is stopped.

Further, at the end of the life of the discharge lamp, etc., the airtightness of the sealed portion of the arc tube 1 is reduced, and the like.
When the starting rare gas therein flows out into the vacuum outer tube 8, a discharge occurs between the electrodes 5a and 5b of the discharge gap 5 due to the pulse voltage at the start of the discharge lamp due to the presence of the rare gas. Therefore, the short-circuit current of the ballast 9 changes to the discharge gap 5
Flow to the current fuse element 4 through the current fuse element 4
Will melt down. If the current fuse element 4 is blown, no more current can flow in the series circuit of the starter 2, so that the starter 2 is permanently inoperable and the discharge lamp does not start. Therefore, it is possible to prevent such a phenomenon that the lamp current increases due to the operation of the discharge lamp in the state where the lamp voltage is low, and the temperature of the ballast 9 rises excessively. Although the high pressure sodium lamp has been described in this embodiment, the same effect can be obtained also in a metal halide lamp in which a rare gas such as argon is enclosed in the arc tube 1 together with mercury and a metal halide.

[0020]

[Embodiment 2] FIG. 4 shows the structure of a second embodiment of the high pressure discharge lamp of the present invention. In the case of the second embodiment shown in FIG. 4, one electrode 5b of the discharge gap 5 is further connected in series to the series circuit of the glow starter 2a and the resistance heating element 2b constituting the starter 2 (the resistance heating element 2b and It is connected to the current fuse element 4. Further, the electrode 5b is composed of a tungsten filament which is heated to a red heat state by an electric current flowing through the series circuit of the starter 2. With such a structure, light emission is achieved. When the starting rare gas starts to flow from the arc tube 1 into the vacuum outer tube 8 due to a decrease in the airtightness of the sealed portion of the tube 1, the electrodes 5a and 5b of the discharge gap 5 are relatively early in the stage. A discharge can be reliably generated between them.

[0021]

[Embodiment 3] FIG. 5 shows the structure of a third embodiment of the high pressure discharge lamp of the present invention. In the case of the third embodiment shown in FIG. 5, the tungsten filament as one electrode 5b of the discharge gap 5 in the second embodiment shown in FIG. 4 also serves as the current fuse element 4. That is, the discharge gap 5
When a short circuit current flows through the ballast 9, the tungsten filament is blown out. In any of the configurations shown in FIGS. 1, 4 and 5, at least one electrode of the discharge gap 5 is coated with or contains an electron emissive material such as a metal oxide, so that the discharge gap The discharge in 5 can be made more reliable.

In each of the embodiments shown in FIGS. 1, 4 and 5, a normal carbon film resistor may be used as the heating resistor 2b. However, in the circuit configuration of the third embodiment shown in FIG. 5, for example, as shown in FIG.
A plate-shaped ceramic heater is used as a substrate, a necessary number of terminals are attached to the surface, and one electrode 5a of the discharge gap 5 and the other electrode 5 made of a tungsten filament are used.
b may be integrally attached to form a unit. In FIG. 6, terminals 14 and 15 of the heating resistor 2b, a terminal 16 for connecting one electrode 5a of the discharge gap 5 and one end of a tungsten filament to be the one electrode 5b of the discharge gap 5 are connected to the first thermal response. A terminal 17 for connecting to the switch 3 and a mounting terminal 18 for holding the entire unit in a proper position inside the outer tube 8 of the discharge lamp are additionally provided on the ceramic substrate.

Next, as a specific example of the high-pressure discharge lamp of the present invention, 22 having the circuit configuration of the third embodiment shown in FIG.
A 0 W high pressure sodium lamp was prototyped. The arc tube 1
The outer diameter was 9 mm, the distance between the electrodes was 58 mm, and xenon was sealed as a rare gas for starting at a pressure of about 27 kPa. The heating resistor 2b connected in series to the glow starter 2a is a square having one side of 25 mm and has resistance values of about 100Ω and 500 at room temperature and a saturation temperature of about 650 ° C., respectively.
A Ω ceramic coated heater was used. As one electrode 5a of the discharge gap 5, a tungsten coil electrode generally used in a high pressure discharge lamp was coated with a mixed oxide of barium, calcium and yttrium as an electron emissive material and fired. As the other electrode 5b of the discharge gap 5, a tungsten wire having a diameter of 95 μm, a mandrel diameter of 580 μm, a pitch of 130 μm
A filament having an effective length of 18 mm wound in step (4) was used and the distance from the electrode 5a was set to 5 mm, and the filament was attached as shown in FIG.

The unit constructed as described above is installed in the outer tube 8 with the surface on which nothing is attached facing the arc tube 1 side, and the closed circuit temperature of the contact is about 100 so as to contact the surface. A glow starter 2a at ℃ was attached. First
The heat-actuated switch 3 and the second heat-actuated switch 7 are designed so that the open circuit temperature is about 150 ° C., and both of them are as close as possible to the arc tube 1 in the outer tube 8 and the starter 2
It was installed at a position away from.

The high-pressure sodium lamp manufactured in this way was passed through a ballast for high-pressure high-pressure mercury lamp of 250 W,
When it was connected to a 0V AC power source, the arc tube 1 started normally through the above-described process and transitioned to a stable lighting state. next,
In order to perform an experiment in a state where the arc tube 1 cannot be started,
After turning off the lamp and cooling, use laser beam,
The current supply line to the arc tube 1 was cut in the outer tube 8 without destroying the outer tube 8 to make the arc tube 1 unstartable.
When the power supply voltage is applied in this state, the current continues to flow in the circuit of the starter 2, the temperature of the ceramic coating heater as the resistance heating element 2b rises rapidly, and the contact of the glow starter 2a closes after about 60 seconds. , The generation of pulse voltage stopped.

Further, in order to realize a state in which a part of xenon as a rare gas for starting flows out from the arc tube 1 into the outer tube 8 due to a decrease in the sealing portion of the arc tube 1, xenon is enclosed together with the arc tube 1. After making the experimental lamp in which the pseudo arc tube with various pressures was held inside the outer tube 8, after the completion of the lamp, a hole was made in the tube wall of this pseudo arc tube by the laser beam by the above-mentioned method, and the xenon was put into the outer tube. It was drained into When the power supply voltage is applied in this state, the xenon pressure calculated in the outer tube 8 becomes 1
Under the condition of 0 Pa or more, discharge occurred in the discharge gap 5 without starting discharge of the arc tube 1, and the tungsten filament was blown.

[0027]

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 resistance heating element.The starter, a normally closed thermal response switch and a current fuse element are connected in series. Connect the circuit in parallel with the arc tube,
Since the discharge gap means is connected in parallel to the starter or the series circuit of the starter and the thermal response switch, the starting voltage of the arc tube will rise significantly at the end of the life of the discharge lamp, or mechanical shock from the outside. When the arc tube becomes unstartable due to disconnection of a part of the current supply line to the arc tube, the glow starter continues to open and close, and the current continues to flow intermittently in the starter. Therefore, the temperature of the resistance heating element rises, the glow starter is heated, and when the contact closing temperature of the glow starter is exceeded, the glow starter always closes. As a result, there is no sudden change in the current flowing through the ballast, and the generation of pulse voltage is stopped.

On the other hand, when the starting rare gas in the arc tube flows out into the outer tube due to a decrease in the airtightness of the arc tube sealing portion or the like, the presence of the rare gas causes discharge by the discharge gap means by the pulse voltage at the start of the discharge lamp. Happens. Therefore, the short-circuit current of the ballast flows into the current fuse element through the discharge gap means, and the current fuse element is blown. Due to the blowout of the current fuse element, no more current can flow in the starter, so that the starter is permanently inoperative and the discharge lamp does not start. Therefore, there is an advantage that it is possible to prevent the insulation of the ballast and the lighting circuit wiring from being lowered and the abnormal temperature rise of the ballast to be prevented.

Further, since the discharge gap means is formed by forming a pair of electrodes on the ceramic substrate, a small gap interval can be easily obtained, so that the gas pressure inside the outer tube for starting the discharge can be easily set. Therefore, at the relatively early stage when the rare gas begins to flow from the arc tube into the vacuum outer tube, it is possible to surely cause the discharge between the electrodes of the discharge gap means. Further, by including an electron emissive substance in at least one of the electrodes of the discharge gap means, the discharge in the discharge gap means can be made more reliable. Also, by using one of the electrodes of the discharge gap means as a tungsten filament connected in series with the starter, the starting rare gas is evacuated from the arc tube due to a decrease in the airtightness of the sealed portion of the arc tube. When it starts to flow into the discharge gap, discharge can be surely caused by the discharge gap means at a relatively early stage. Further, by making the tungsten filament also function as the current fuse element, the number of parts can be reduced, the structure of the high-pressure discharge lamp can be simplified, and the discharge in the discharge gap means can be made more reliable. it can. In addition, the resistance heating element of the starter has a flat plate shape, and the current fuse element and the discharge gap means are integrated on the surface of the resistance heating element. Can be prevented.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a component structure of a discharge gap in the first embodiment.

FIG. 3 is an enlarged view of an essential part showing the arrangement of parts in the first embodiment.

FIG. 4 is a schematic diagram showing a circuit configuration of a second embodiment of the high pressure discharge lamp of the present invention.

FIG. 5 is a schematic diagram showing a circuit configuration of a third embodiment of the high pressure discharge lamp of the present invention.

FIG. 6 is a perspective view showing a unit of component parts of a high pressure discharge lamp according to a third embodiment.

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

FIG. 8 is a schematic diagram showing a circuit configuration of another conventional high pressure discharge lamp.

[Explanation of symbols]

 1: arc tube 2: starter 2a: glow starter 2b: resistance heating element 3: first thermal response switch 4: current fuse element 5: discharge gap 5a: one electrode of discharge gap 5b: other electrode of discharge gap 8: Outer tube 9: Ballast 10: Power supply voltage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hong Gion 1-1, Saiwaicho, Takatsuki City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd.

Claims (7)

[Claims] 1. An outer tube having a vacuum inside of a light emitting tube having a pair of electrodes on both ends and having a light emitting substance sealed therein, and a starter for applying a pulse voltage between both electrodes of the light emitting tube. The high-pressure discharge lamp installed in, wherein the starter is composed of a series circuit of a glow starter and a resistance heating element, wherein the starter, a normally closed thermal response switch and a current fuse element in series are parallel to the arc tube. And a discharge gap means is connected in parallel to the starter or a series body of the starter and the heat responsive switch, and the glow starter includes the resistance heating element when the arc tube does not start. The discharge gap means is provided at a position that is always closed by heat from the discharge tube, and when the starting rare gas flows out of the arc tube into the outer tube, the current fuse element is connected through the discharge gap means. A high-pressure discharge lamp, which is arranged so as to melt the child. 2. The high pressure discharge lamp according to claim 1, wherein the discharge gap means is formed by forming a pair of electrodes on a ceramic substrate. 3. One of the electrodes of the discharge gap means,
The high pressure discharge lamp according to claim 1, which is a tungsten filament connected in series to the starter. 4. The high pressure discharge lamp according to claim 3, wherein the tungsten filament further has a function of the current fuse element. 5. The high pressure discharge lamp according to claim 1, wherein at least one of the electrodes of the discharge gap means contains an electron emitting substance. 6. The high pressure discharge lamp according to claim 1, wherein the resistance heating element of the starter is a ceramic heater. 7. The high-voltage discharge according to claim 1, wherein the resistance heating element of the starter has a flat plate shape, and a current fuse element and a discharge gap unit are integrated on the surface of the resistance heating element. lamp.