JPH08250065A - Ceramics discharge lamp, its lighting device and lighting system - Google Patents

Abstract

PURPOSE: To provide a ceramics discharge lamp having a long life which can prevent frickering out by effectively preventing mercury rich while eliminating necessity for a starting pulse, by providing a constitution such that rare gas and only sodium as a luminescent metal are sealed in a luminous tube. CONSTITUTION: A ceramics discharge lamp comprises a luminous tube 2 formed of permeable alumina ceramics sealing at least sodium, rare gas as starting gas in the luminous tube 2 to decrease starting voltage to eliminate necessity for a starting pulse and a means of generating a discharge in the luminous tube 2. Only sodium as a luminescent metal, sealed in the luminous tube 2, is used to set a seal amount of this sodium larger than the amount evaporated during lighting the lamp. A sodium seal amount is preferable 0.120mg/cc or more per unit volume of the luminous tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to at least sodium (N) in an arc tube made of translucent alumina ceramics.
The present invention relates to a ceramics discharge lamp such as a high pressure sodium lamp in which a) is enclosed, a lighting device for the same, and a lighting device.

[0002]

2. Description of the Related Art Conventionally, as an arc tube for a high-pressure sodium lamp of this type, a translucent alumina (A) which is stable to sodium and is also excellent in strength, heat resistance and translucency.
An arc tube made of l ₂ O ₃ ) ceramics is used.

In the arc tube made of translucent alumina ceramics, appropriate amounts of mercury and sodium (N
a) and, for example, xenon (Xe) are enclosed and the xenon gas pressure is increased to significantly improve the lamp efficiency.

However, since this xenon gas has a high starting voltage (discharge starting voltage), a dedicated ballast with an igniter (pulse generation circuit) is required, and for starting a high voltage of about 1000 to 3000 V from this igniter, for example. A pulse is applied between the pair of electrodes so as to be superimposed on the power supply voltage, discharge is started in the arc tube, and the arc tube is lit (started). The output of the lighting pulse is stopped after the lamp is lit.

However, when the arc tube is not lit at the end of its life due to some reason, this high-voltage starting pulse is repeatedly output from the igniter, which causes electromagnetic wave noise and dielectric breakdown between wirings. Therefore, there is a possibility that wiring short circuit or fusing may occur.

Further, there is a problem in that an expensive and large-sized dedicated device with an igniter must be used as the ballast.

Therefore, for example, neon (Ne) and argon (A) are used as the starting gas for lowering the starting voltage so that the pulse starting by the igniter becomes unnecessary.
It is considered that the mixed gas with r) is filled in the arc tube instead of xenon.

However, this noble gas lowers the starting voltage as well as the lamp efficiency. Therefore,
In order to prevent such a decrease in lamp efficiency, it is conceivable to increase the wattage charged to the arc tube to increase the wall load.

However, when the load on the tube wall is increased, the lamp temperature rises. This time, alumina (Al ₂ O ₃ ) which is a constituent material of the arc tube and sodium (N) which is a luminescent metal are used.
The reactivity with a) or sodium ion is increased to increase the amount of reactants produced. As a result, the disappearance amount of sodium as a luminescent metal increases.

For this reason, the phenomenon that the ratio of the enclosed amount of mercury to sodium is apparently increased, that is, so-called mercury rich, and the lamp voltage rises. As a result, there is a problem of short life in that the discharge during lighting cannot be maintained and disappears.

Further, since sodium, which is a luminescent metal, disappears, there is a problem that luminous efficiency is lowered and luminous flux is lowered.

The present invention has been made in consideration of the above circumstances, and its purpose is to eliminate the need for a starting pulse and to prevent extinction by effectively preventing mercury rich, etc. An object of the present invention is to provide a discharge lamp, its lighting device, and a lighting device.

[0013]

The present invention is configured as follows in order to solve the above-mentioned problems.

The invention according to claim 1 of the present application is an arc tube made of translucent alumina ceramics for enclosing at least sodium; and a starting voltage is enclosed in this arc tube as a starting gas so that a starting pulse is unnecessary. In a ceramic discharge lamp having: a rare gas that reduces the emission of light; and a means for generating a discharge in the arc tube, the luminescent metal sealed in the arc tube is only the sodium, and the sealed amount is during lighting of the lamp. It is characterized in that it is larger than the amount that evaporates.

According to the second aspect of the present invention, the amount of sodium enclosed is 0.120 mg per unit volume of the arc tube.
/ Cc or more.

Further, the invention according to claim 3 of the present application is
An arc tube made of translucent alumina ceramics that encapsulates at least sodium; a rare gas that is encapsulated as a starting gas in the arc tube to reduce the starting voltage so that a starting pulse is unnecessary; and a discharge is generated in the arc tube. In the ceramic discharge lamp having means for suppressing the discharge lamp, the luminescent metal sealed in the arc tube is only the sodium, and the sealed amount is an amount that almost entirely evaporates during the lighting of the lamp. .

Furthermore, in the invention according to claim 4 of the present application, the amount of sodium enclosed is 0.0 per unit volume of the arc tube.
It is characterized in that it is 05 to 0.120 mg / cc.

According to the invention of claim 5 of the present application, an arc tube made of translucent alumina ceramics enclosing at least sodium; and a starting gas is enclosed in the arc tube so that a starting pulse is unnecessary. A ceramic discharge lamp comprising: a rare gas that lowers a starting voltage; and a means that generates a discharge in the arc tube.
The luminescent metals sealed in the arc tube are sodium and mercury, and the sealed amount of these is almost the entire amount that evaporates while the lamp is on.

Further, the invention according to claim 6 of the present application is
The rare gas is characterized by being a mixed gas of neon and argon.

Furthermore, the invention according to claim 7 of the present application is characterized in that the starting voltage is 500 V or less.

Further, the invention according to claim 8 of the present application is characterized by comprising an outer tube for accommodating the arc tube.

Further, the invention according to claim 9 of the present application is
A light emitting tube made of the translucent alumina ceramic according to any one of claims 1 to 8 is characterized in that sodium is enclosed as a light emitting metal.

Furthermore, the invention according to claim 10 of the present application is the ceramic discharge lamp according to any one of claims 1 to 8, or the high-pressure sodium lamp according to claim 9, and this discharge lamp or lamp. And a lighting circuit for stably lighting the power by supplying electric power.

The invention according to claim 11 of the present application is
It is characterized by comprising the ceramic discharge lamp according to any one of claims 1 to 8 or the high-pressure sodium lamp according to claim 9 and an instrument main body for housing the discharge lamp or the lamp.

It is characterized in that

Furthermore, the invention according to claim 10 of the present application is the ceramic discharge lamp according to any one of claims 1 to 7, or the high-pressure sodium lamp according to claim 8, and this discharge lamp or lamp. And a device main body that accommodates.

[0027]

A discharge lamp according to any one of claims 1 to 8,
Alternatively, in the high-pressure sodium lamp according to claim 9, since a rare gas that reduces the starting voltage such as a mixed gas of neon and argon is enclosed in an arc tube made of translucent alumina ceramics, a high-pressure starting pulse is used. No need to start. For this reason, a pulse generating circuit such as an igniter can be omitted, and a wiring short circuit or a fusing due to a dielectric breakdown between the wiring due to continuous output of a high-voltage starting pulse when the arc tube is imperfect, and an electromagnetic wave Noise can be prevented in advance.

The ceramic discharge lamp according to any one of claims 1, 2 or 5 to 8 or the high pressure sodium lamp according to claim 9 uses only sodium.
The total amount is almost completely evaporated while the lamp is lit, so more than the so-called complete evaporation amount is enclosed in the arc tube,
In order to improve the lamp efficiency, the wattage charged to the arc tube is increased to increase the load on the tube wall, and the reactivity of alumina (Al ₂ O ₃ ) which is a constituent material of the arc tube and sodium which is a luminescent metal is high, Even if the amount of sodium lost increases, the amount lost can be supplemented with a surplus.

Further, since mercury is not enclosed in the arc tube, it is possible to prevent the phenomenon that the apparent amount of enclosed mercury is larger than that of sodium, that is, so-called mercury rich.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since the lost amount of sodium can be replenished by the surplus amount, it is possible to prevent or suppress the decrease in the evaporation amount during lighting, and therefore, it is possible to prevent the luminous efficiency from decreasing. Can be maintained.

Further, the ceramic discharge lamp according to any one of claims 3, 4 or 6 to 8 or the high pressure sodium lamp according to claim 9 uses only sodium.
Almost all of it evaporates almost completely while the lamp is on, so only the so-called complete evaporation amount is enclosed in the arc tube, so in order to improve the lamp efficiency, increase the watt input to the arc tube to reduce the wall load. As a result, the reactivity between alumina (Al ₂ O ₃ ) which is the constituent material of the arc tube and sodium which is the light emitting metal is high, and even if the amount of sodium lost increases, mercury is not enclosed in the arc tube. Therefore, it is possible to prevent the phenomenon that the apparent amount of mercury is larger than that of sodium, that is, so-called mercury rich.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since there is no surplus in the enclosed sodium, for example, when the arc tube is subjected to external vibration, the surplus sodium moves to a high temperature portion in the arc tube, the sodium vapor pressure rises rapidly, and the lamp voltage is increased. It is possible to prevent the phenomenon in which the rises and disappears.

Further, even if the power supply voltage of the lamp fluctuates, almost all the amount of sodium is evaporated, so that fluctuation of the vapor pressure of sodium can be almost prevented. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

The ceramic discharge lamp according to any one of claims 5 or 6 to 8 or the high pressure sodium lamp according to claim 9 contains mercury and sodium.
Almost all of it evaporates almost completely while the lamp is lit. Only the so-called complete evaporation amount is enclosed in the arc tube, so the wattage to the arc tube is increased to improve the lamp efficiency. And the reactivity of alumina (Al ₂ O ₃ ) which is a constituent material of the arc tube and sodium which is a luminescent metal is high and the amount of sodium disappeared increases,
Since the enclosed amount of mercury is the complete evaporation amount, that is, a very small amount, the rise of the lamp voltage can be prevented or suppressed. For this reason, it is possible to prevent the light from going out during lighting, and it is possible to prolong the life.

Further, since the enclosed sodium has no surplus, it is possible to prevent the excess sodium from moving to a high temperature portion in the arc tube when the arc tube is subjected to external vibration. Therefore, it is possible to prevent a phenomenon in which the sodium vapor pressure sharply rises due to the movement of sodium, the lamp voltage rises, and the lamp goes out.

Further, even if the power supply voltage of the lamp fluctuates, sodium is almost completely evaporated, so that fluctuation of the vapor pressure of sodium can be almost prevented. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

A lighting device according to claim 10 and claim 11.
The lighting device described does not require an expensive and large igniter that is a pulse generation circuit, and is equipped with a ceramic discharge lamp such as a high-pressure sodium lamp that can use an inexpensive general-purpose ballast, so that the cost is reduced. It can be reduced.

Further, since the ceramic discharge lamp has a long life which can prevent the lamp from being extinguished during lighting, it is possible to provide a lighting device and a lighting device which can prevent the extinguishing.

[0041]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a partial vertical cross-sectional view of an embodiment in which the present invention is applied to a high-pressure sodium lamp, in which the high-pressure sodium lamp 1 is lit at a starting voltage of 500 W or less, for example. Then, the arc tube 2 is made of translucent alumina (Al ₂ O ₃ ) ceramics, for example, in a closed cylindrical shape.
b, through holes 3a, 3b are formed, and niobium Nb or niobium Nb is formed in these through holes 3a, 3b.
4a, 4 made of an alloy of zirconium and zirconium Zr
b is inserted, and the conductors 4a and 4b are airtightly joined to the through holes 3a and 3b by the glass sealing agents 5a and 5b.

Electrodes 6a, 4a, 4b are formed on the inner ends of the conductors 4a, 4b, respectively.
6b is welded. Each of the electrodes 6a, 6b is formed by winding electrode coils 8a, 8b made of tungsten a plurality of times around the tip ends of electrode shafts 7a, 7b made of tungsten, and these electrode coils 8a, 8b are made of, for example, BaO. It is coated with an electron emissive material (emitter) such as -CaO-WO _3.

The arc tube 2 having such a structure has, for example, a total length of 8
8mm, outer diameter 8.55mm, inner diameter 6.85mm, wall thickness 0.85
In this arc tube 2, an appropriate amount of mixed gas of sodium Na and neon (Ne) and argon (Ar) as a rare gas for starting is enclosed, and mercury is not enclosed. Then, the amount of sodium that is almost completely evaporated during the lighting of the lamp, that is, a larger amount than the total amount of evaporation is filled. For example, 1.65 mg / cc is filled per unit volume of the arc tube 2, and the excess sodium 9 is left in the coldest part in the arc tube 2, for example, the outer peripheral corner on the lower end 2b.

Therefore, since only sodium is enclosed in the arc tube 2 in a larger amount than the complete evaporation amount, in order to improve the lamp efficiency, the watt supplied to the arc tube is increased to increase the load on the wall of the arc tube to cause the light emission. Alumina (Al
₂ O ₃ ) and sodium, which is a luminescent metal, have high reactivity, and even if the amount of sodium, which is a luminescent metal, is increased,
The lost amount can be replenished with a surplus amount.

Further, since mercury is not enclosed in the arc tube 2, it is possible to prevent the phenomenon that the apparent amount of enclosed mercury is larger than that of sodium, that is, so-called mercury rich.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since the lost amount of sodium can be replenished by the surplus amount, it is possible to prevent or suppress the decrease of the evaporation amount of sodium during lighting, and thus to prevent the reduction of the luminous efficiency. Yes, the luminous flux can be increased.

On the other hand, the mixed gas of neon and argon lowers the discharge starting (starting) voltage so that it is not necessary to light it by a high-voltage starting pulse.
An expensive igniter that outputs a high-voltage starting pulse can be omitted, and both the number of parts and the cost can be reduced. Also, since the igniter can be omitted, if the arc tube 2 during its life does not light up for some reason, electromagnetic noise is generated by the high-voltage starting pulse repeatedly output from the igniter, or the insulation between the wirings is destroyed. At the very least, it is possible to prevent the occurrence of wiring short-circuiting and fusing beforehand.
Further, the encapsulation amount of the mixed gas of neon and argon into the arc tube 2 is 99.5% and 0.5% in terms of mol ratio.
Although it is 0 torr (normal temperature), it is not limited to this value as long as the Penning effect can be obtained.

As in the arc tube 2c shown in FIG. 2, both ends in the axial direction are open, and a pair of upper and lower end plugs 2 made of an alumina ceramic disk are provided in the both open ends.
When d and 2e are fitted and they are airtightly fixed to the arc tube 2c with an adhesive such as the glass solder 10, when the excess sodium 9a of the enclosed metal comes into contact with the glass solder 10, they react with each other. As a result, the airtightness of the arc tube 2c is lowered or broken. For this purpose, for example, the lower conductor 4b is formed in a medium volume, and the excess sodium 9a is stored therein, while the lower conductor 4b is stored.
A small hole 11 is opened at the inner end of b to remove excess sodium 9
A may be connected to the inside of the arc tube 2c to prevent the excess sodium 9a from contacting and reacting with the glass solder 10 to eliminate the above-mentioned inconvenience.

The enclosed amount of sodium may be set to the complete evaporation amount. Here, the complete evaporation amount is an amount by which almost all the amount of sodium is evaporated almost completely while the lamp is on, and it is an amount that may be slightly left in the evaporation tubes 2 and 2c. For example, the almost complete evaporation of sodium is
0.007 to 0.120 mg / cc per unit volume of 2c.

As described above, when the amount of enclosed sodium is the complete evaporation amount, the arc tube 2, in order to improve the lamp efficiency.
The wattage charged to 2c is increased to increase the load on the tube wall, and alumina (Al ₂ O ₃ ) which is a constituent material of the arc tubes 2 and 2c,
Even if the reactivity with sodium, which is a luminescent metal, is high and the amount of sodium lost increases, mercury is not enclosed in the arc tubes 2 and 2c, so the apparent amount of mercury enclosed is sodium enclosed. It is possible to prevent a phenomenon in which the amount is larger than the amount, so-called mercury rich, in advance.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since there is no surplus in the enclosed sodium, it is possible to prevent the surplus sodium 9a from moving to a high temperature portion in the arc tubes 2 and 2c when external vibration is applied to the arc tubes 2 and 2c. be able to. Therefore, it is possible to prevent the vapor pressure of sodium from abruptly rising due to the movement of sodium and the lamp voltage from rising and extinguishing.

Further, even if the power supply voltage of the lamp fluctuates, the sodium is almost completely evaporated, so that the fluctuation of the vapor pressure of sodium can be almost prevented. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

Further, the arc tubes 2 and 2c may be filled with a completely evaporated amount of mercury and sodium amalgam. In this case, alumina (Al ₂ O ₃ ) which is a constituent material of the arc tube and sodium which is a luminescent metal are used even if the wattage supplied to the arc tube is increased to increase the tube wall load in order to improve the lamp efficiency. Even if the reactivity is high and the disappearance amount of sodium increases, the amount of mercury enclosed is the complete evaporation amount, that is, a very small amount, so that the rise of the lamp voltage can be prevented or suppressed. For this reason, it is possible to prevent the light from going out during lighting, and it is possible to achieve a long life.

Since there is no surplus in the enclosed sodium, it is possible to prevent the excess sodium 9a from moving to a high temperature portion in the arc tube when the arc tubes 2 and 2c are subjected to external vibration. Therefore, it is possible to prevent the vapor pressure of sodium from abruptly rising due to the movement of sodium and the lamp voltage from rising and extinguishing.

Further, even if the power supply voltage of the lamp fluctuates, the sodium vapor is almost completely evaporated, so that the fluctuation of the vapor pressure of sodium can be almost prevented. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

FIG. 3 is a high-pressure sodium lamp 1 shown in FIG.
The high pressure sodium lamp 21 in which the arc tube 2 is housed in a translucent outer tube 22 made of, for example, hard glass is shown. That is, the high pressure sodium lamp 21 has an outer tube 22.
Is formed of hard glass, a bulge is formed in the center thereof, and a small diameter top portion 23a and a neck portion 23b are formed in the upper and lower portions thereof to form a so-called BT shape. A cap 24 is attached to the end of the neck portion 23b. Outer tube 2
The inside of 2 is kept vacuum.

The arc tube 2 shown in FIG. 1 is housed in the outer tube 22, and the arc tube 2 is supported by the support wire 25 in the outer tube 22. Support wire 2
Reference numeral 5 denotes a conductive wire such as stainless steel formed in a square frame shape, and the upper part of the outer tube 22 is provided with an elastic piece 26.
While being locked in the top part 23a of the above, the lower part is welded to one sealing line 28a sealed to the stem 27.

One conductor 4a led out from the upper end of the arc tube 2 is electrically and mechanically connected to the support wire 25 through an upper conductive holder 29a which also serves as a conductive wire. The other conductor 4b led out from the lower end of the arc tube 2 is mechanically supported by another lower holder 29b via an insulator, and this lower holder 29b is mechanically attached to the support wire 25. . Therefore, the arc tube 2 has holders 29a, 29b at the upper and lower ends.
And is supported by the support wire 25 via the holders 29a and 29b.

The lower conductor 4b of the arc tube 2 is connected to the lead wire 3
It is electrically connected to another sealing wire 28b which is sealed to the stem 27 through 0. These sealing wires 28a and 28b are connected to the shell 24a of the base 24 and the external terminals 24b.

On the outer surface of the arc tube 2, a proximity conductor 31 for assisting the starting is arranged in close proximity or spirally wound. The proximity conductor 31 is made of a refractory metal made of at least one kind of molybdenum, tungsten, tantalum, niobium, iron, nickel, etc., one end of which is supported by a piece of bimetal 33 and the other end of which is attached to the upper holder 29a. It is supported by the formed locking portion. Reference numeral 32 is a getter, which can be configured as a metal halide lamp by replacing the above sodium with sodium of a metal halide.

High-pressure sodium lamp 1 having such a configuration
1 is used as a light source of a lighting device 31, as shown in FIG. 4, for example. That is, the illuminating device 31 has a reflecting surface 32a on the inner surface of the luminaire main body 32, and has a housing structure in which the lower surface or one side surface is opened. A socket 34 is attached to the side wall of the luminaire body 32, and the base 14 of the high-pressure sodium lamp 11 is screwed into the socket 34 and attached to the luminaire body 32.

The socket 34 is adapted to be connected to a commercial power supply 36 via a lighting circuit 35 which is attached to the lighting fixture main body 32 or which is provided outside the fixture main body 32 and includes a ballast. The power supply voltage is 200V and the lamp voltage is 130V ± 10V. This lighting circuit 45
Is a general-purpose ballast that has a choke coil and a power factor improving capacitor, and does not have an igniter that outputs a high-voltage pulse for starting. That is, since the starting gas is low because the rare gas sealed in the arc tube 1 is a mixed gas of neon and argon, a high-voltage starting pulse is unnecessary.

[0066]

As described above, according to the present invention, since a rare gas, such as a mixed gas of neon and argon, which lowers the starting voltage is enclosed in the arc tube made of translucent alumina ceramics, a high pressure There is no need to start with a start pulse. For this reason, it is possible to prevent wiring short-circuiting or fusing due to insulation breakdown between wirings due to continuous output of a high-voltage starting pulse when the arc tube is imperfect, and electromagnetic noise.

Further, since almost all the amount of sodium is almost completely evaporated during the lighting of the lamp, that is, a larger amount than the so-called complete evaporation amount is enclosed in the arc tube, it is possible to improve the lamp efficiency. Alumina (Al which is a constituent material of the arc tube
₂ O ₃ ) and sodium, which is a luminescent metal, have high reactivity, and even if the amount of sodium, which is a luminescent metal, is increased,
The lost amount can be replenished with a surplus amount.

Further, since mercury is not enclosed in the arc tube, it is possible to prevent the phenomenon that the apparent amount of enclosed mercury is larger than that of sodium, that is, so-called mercury rich.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since the lost amount of sodium can be replenished by the surplus amount, it is possible to prevent or suppress the decrease of the evaporation amount during lighting, and therefore, it is possible to prevent the luminous efficiency from decreasing. The luminous flux can be increased.

Also, since only the so-called complete evaporation amount of sodium, which is almost completely evaporated during lamp operation, is enclosed in the arc tube, the sodium is injected into the arc tube in order to improve the lamp efficiency. Alumina (Al which is a constituent material of the arc tube
₂ O ₃ ) has a high reactivity with sodium, which is a luminescent metal, and even if the amount of sodium lost increases, mercury is not enclosed in the arc tube, so the apparent amount of mercury enclosed is sodium. It is possible to prevent a phenomenon in which the amount is larger than the enclosed amount, that is, so-called mercury rich.

As a result, it is possible to prevent or suppress an increase in the lamp voltage due to mercury rich, so that it is possible to prevent the lamp from extinguishing during lighting and to prolong the life.

Further, since the enclosed sodium has no surplus, it is possible to prevent the surplus sodium from moving to a high temperature portion in the arc tube when external vibration is applied to the arc tube, for example. Therefore, it is possible to prevent the vapor pressure of sodium from rapidly rising due to the movement of sodium and the lamp voltage from rising to cause extinction.

Further, even if the power supply voltage of the lamp fluctuates, since sodium is almost completely evaporated, it is possible to prevent fluctuation of the vapor pressure of sodium. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

Further, since almost all of mercury and sodium are almost completely evaporated while the lamp is lit, only so-called complete evaporation amounts are enclosed in the arc tube, respectively.
In order to improve the lamp efficiency, the wattage charged into the arc tube is increased to increase the load on the tube wall, and the reactivity between alumina (Al ₂ O ₃ ) which is a constituent material of the arc tube and sodium which is a luminescent metal is high, Even if the disappearance amount of sodium increases, the amount of mercury enclosed is a complete evaporation amount, that is, a very small amount, so that an increase in the lamp voltage can be prevented or suppressed. For this reason, it is possible to prevent the light from going out during lighting, and it is possible to prolong the life.

Furthermore, since there is no surplus in the enclosed sodium, it is possible to prevent the excess sodium from moving to a high temperature portion in the arc tube when external vibration is applied to the arc tube. Therefore, it is possible to prevent the vapor pressure of sodium from abruptly rising due to the movement of sodium and the lamp voltage from rising and extinguishing.

Further, even if the power supply voltage of the lamp fluctuates, the sodium vapor is almost completely evaporated, so that the fluctuation of the vapor pressure of sodium can be almost prevented. Therefore, the fluctuation of the lamp voltage can be prevented or suppressed, so that the lighting stability can be improved.

A lighting device according to claim 10 and claim 11.
The lighting device described does not require an expensive igniter that is a pulse generation circuit, and is equipped with a ceramic discharge lamp such as a high-pressure sodium lamp that can use an inexpensive general-purpose ballast, so that the cost can be reduced. You can

Further, since the ceramic discharge lamp has a long service life capable of preventing extinction during lighting, it is possible to provide a lighting device and a lighting device capable of preventing extinction.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an example of a high pressure sodium lamp which is an example of a ceramics discharge lamp according to the present invention.

FIG. 2 is a vertical sectional view of an example of a high-pressure sodium lamp according to another embodiment of the present invention.

FIG. 3 is a front view of an example of a high-pressure sodium lamp with an outer tube in which the high-pressure sodium lamp shown in FIG. 1 is housed in an outer tube.

FIG. 4 is a configuration diagram of an embodiment of a lighting device and a lighting device according to the present invention.

[Explanation of symbols]

 1,11 High-pressure sodium lamp 2,2c Arc tube 3a, 3b Pair of through holes 4a, 4b Pair of conductors 6a, 6b, 15a, 15b Pair of electrodes 9,9a Excess sodium 10 Glass solder 11 Small hole 12 Outer tube 14 Base 15 Support wire 17 Stem 21 Proximity conductor 31 Lighting device 32 Lighting fixture body 32a Reflective surface 34 Socket 35 Lighting circuit 36 Power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Issei Uchida 4-3-1 Higashi-Shinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation (72) Takayuki Aoki 4-3-1, Higashi-Shinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation

Claims (11)

[Claims] 1. An arc tube made of translucent alumina ceramics enclosing at least sodium; a rare gas enclosed as a starting gas in the arc tube to reduce a starting voltage so that a starting pulse is unnecessary; In a ceramic discharge lamp having means for generating an electric discharge in the tube, the luminous metal enclosed in the arc tube is only the sodium, and the amount of the encapsulation is larger than the amount evaporated during the lighting of the lamp. A ceramic discharge lamp characterized in that 2. The ceramic discharge lamp according to claim 1, wherein the amount of sodium enclosed is 0.120 mg / cc or more per unit volume of the arc tube. 3. An arc tube made of translucent alumina ceramics enclosing at least sodium; a rare gas enclosed as a starting gas in the arc tube to reduce a starting voltage so that a starting pulse is unnecessary; In a ceramic discharge lamp having means for generating an electric discharge in the tube, the luminescent metal sealed in the arc tube is only the sodium, and the sealed amount is an amount that almost entirely evaporates during lighting of the lamp. A ceramic discharge lamp characterized in that 4. The ceramic discharge lamp according to claim 3, wherein the amount of sodium enclosed is 0.005 to 0.120 mg / cc per unit volume of the arc tube. 5. An arc tube made of translucent alumina ceramics enclosing at least sodium; and a rare gas encapsulated as a starting gas in the arc tube to reduce the starting voltage so that a starting pulse is unnecessary; In the ceramic discharge lamp having means for generating a discharge in the arc tube, the luminescent metals sealed in the arc tube are sodium and mercury, and the sealed amounts of these are almost all while the lamp is on. A ceramics discharge lamp characterized by the amount of evaporation. 6. The ceramic discharge lamp according to claim 1, wherein the rare gas is a mixed gas of neon and argon. 7. The ceramic discharge lamp according to claim 1, wherein the starting voltage is 500 V or less. 8. The ceramic discharge lamp according to claim 1, further comprising an outer tube accommodating an arc tube. 9. A high-pressure sodium lamp, characterized in that sodium is enclosed as a light-emitting metal in the light-transmitting alumina ceramics arc tube according to any one of claims 1 to 8. 10. The ceramic discharge lamp according to any one of claims 1 to 8, or the high-pressure sodium lamp according to claim 9, and lighting for stably lighting by supplying electric power to the discharge lamp or the lamp. A lighting device comprising a circuit. 11. A ceramic discharge lamp according to any one of claims 1 to 8 or a high pressure sodium lamp according to claim 9, and an instrument main body for housing this discharge lamp or lamp. Lighting device.