JPH0917389A - High pressure discharge lamp, lighting device and lighting system - Google Patents

Abstract

PURPOSE: To improve a color rendering property particularly to a green color without reducing lamp efficiency, and lengthen the service life by using Na and Xe as a discharge medium, and setting a tube wall load, lamp electric current density, Xe pressure and an electric potential gradient in prescribed conditions. CONSTITUTION: Preferably, in a high pressure discharge lamp where Na and Xe are sealed in a light transmissive alumina ceramics made or quartz glass-made airtight vessel where a nitriding reforming layer is formed on an inside surface, an inside diameter of the vessel is set is D, and a distance between a pair of electrodes is set in L. When lamp voltage is VL and lamp electric power is WL, a tube wall load WL/πDL, lamp electric current density IL/π (D/2)<2> , XePxe and an electric current gradient VL/L are set in conditions expressed by an expression. Therefore, molecular light emission of Na-Xe is enhanced, and reduction in lamp efficiency and reduction in a light flux maintenance factor by reaction between a vessel material and Na are prevented. Use of Hg is also canceled. Preferably, characteristics are set so that lamp efficiency is not less than 100lm/w, and R3 is not less than 50 and a color temperature is not less than 2200K.

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 such as a high pressure sodium lamp in which at least sodium (Na) is enclosed in a bulb of an arc tube made of translucent alumina ceramics or quartz, a lighting device and a lighting device.

[0002]

2. Description of the Related Art Conventionally, as an airtight container material for an arc tube of a high-pressure sodium lamp of this type, a light-transmissive alumina (Al ₂₎ which is stable to sodium and is also excellent in strength, heat resistance and light transmission property. O ₃ ) ceramics are used.

In the airtight container 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.

[0004]

However, in such a conventional high-pressure sodium lamp, since the molecular emission of Na-Hg is higher than that of Na-Xe, the color temperature of the light color is about 2000K. It has a low color rendering property to green.

For this reason, there is a problem that the usage of this high-pressure sodium lamp is low and the demand is low in a park with lots of greenery such as trees.

[0006] Therefore, a method of increasing the color rendering property by increasing the sodium vapor pressure P _Na of the high-pressure sodium lamp to increase the D-ray absorption width is conceivable. However, this rather reduces the lamp efficiency significantly. There is a problem.

Further, in such a high-pressure sodium lamp, alumina (Al ₂ O) which is a constituent material of the arc tube bulb is used.
₃ ) or quartz reacts with sodium (Na), which is a luminescent metal, to generate a reaction product, so-called sodium disappearance occurs. As a result, the enclosed mercury increases relatively, the lamp voltage is raised, and problems such as extinguishing occur, and the luminous flux maintenance factor decreases due to a decrease in the number of luminescent materials, resulting in a decrease in life and a change in light color. large.

As a conventional technique for reducing the loss of sodium, Japanese Patent Laid-Open No. 62-262358 discloses a method of coating the inner surface of an alumina arc tube with aluminum nitride to lower the temperature of the central part of the arc tube. It is disclosed. However, since this prior art has a structure in which a special aluminum nitride film is formed on the inner surface of the arc tube bulb, the difference in the thermal expansion coefficient between the arc tube material and those films results in a silicon nitride film or The aluminum nitride film may be cracked, peeled off, or dropped.

With respect to this point, the prior art publication discloses that the film thickness of the aluminum nitride film may be 5 μm or less, but cracks may occur even if the film thickness is 5 μm or less. However, it is difficult to form a sufficiently effective film, and such a film has not been put to practical use at present.

Therefore, an object of the present invention is to provide a long-life high-pressure discharge lamp, a lighting device, and a lighting device which can improve the color rendering properties, particularly the color rendering properties for green color, without lowering the lamp efficiency. .

[0011]

According to the first aspect of the present invention,
An airtight container in which sodium and xenon are enclosed; a pair of electrodes for generating a discharge in the airtight container;
When the distance between the pair of electrodes is L, the inner diameter of the airtight container is D, the lamp voltage is V _L , and the lamp power is W _L , the tube wall load W _L / πDL and the lamp current density I _L / π (D /
2) ² , Xe pressure Pxe and potential gradient _VL / L satisfy the following conditions.

[0012]

(Equation 2)

The airtight container is a bulb of an arc tube or the like, and is made of a translucent alumina ceramics tube or a quartz tube. The tube wall load is a value obtained by dividing the input lamp power WL by the area inside the airtight container corresponding to the space between the electrodes.

The invention according to claim 2 is the invention according to claim 1, which further has characteristics that the lamp efficiency is 100 lm / W or more, R3 is 50 or more, and the color temperature is 2200K or more.

The third aspect of the present invention provides the first or second aspect.
In the invention described above, a heat insulating member is further provided around the pair of electrodes of the airtight container.

The invention described in claim 4 is the first to third aspects of the present invention.
The invention further comprises a layer containing nitrogen atoms formed on at least the inner surface of the airtight container.

Here, the layer containing nitrogen atoms is, for example, a nitriding modified layer formed by substituting nitrogen for oxygen component of alumina ceramics or quartz which is a constituent material of the arc tube bulb.
The nitride modified layer may be formed on the outer surface of the arc tube bulb. Since this nitriding modified layer has the property of improving the thermal conductivity, it becomes possible to effectively release the heat of the locally high temperature part to the other low temperature part, so that the occurrence of thermal strain is eliminated. It is possible to prevent damage. From this point, the durability of the arc tube is improved.

A fifth aspect of the invention is the invention according to the fourth aspect, wherein the airtight container is made of translucent alumina ceramics.

The invention according to claim 6 is the invention according to claim 4, wherein the airtight container is made of quartz glass.

[0020] The invention according to claim 7 is the invention according to claims 1 to 6.
The invention includes a high-pressure discharge lamp; and a lighting circuit for supplying electric power to the high-pressure discharge lamp to illuminate it stably.

[0021] The invention according to claim 8 is the invention according to claims 1 to 6.
The invention according to claim 1, further comprising: a high-pressure discharge lamp; and a main body of an instrument that accommodates the high-pressure discharge lamp.

[0022]

In each of the first to sixth aspects of the invention, for example, by reducing the tube diameter of the airtight container to a predetermined value, the tube wall load W _L / πDL and the lamp current density I _L / π (D / 2) ² ,
The Xe pressure Pxe and the potential gradient _VL / L are set within the predetermined conditions of [Equation 1] to increase the molecular emission of Na-Xe.

When W _L / πDL <14 W / cm ² , the lamp efficiency is drastically reduced, and when W _L / πDL> 20 W / cm ² , the alumina tube or the quartz tube reacts with the encapsulated Na and Na disappears. The luminous flux maintenance factor (% lm) is greatly reduced and the life is short.

At I _L / π (D / 2) ² <10 A / cm ² , Na-Xe molecular emission is small and I _L / π (D / 2) ² >.
At 35 A / cm ² , the luminous flux maintenance factor is greatly reduced and the life is short.

When V _L / L <15 V / cm, Pxe is low,
The decrease in lamp efficiency is large, and when V _L / L> 25 V / cm, the D-line absorption width is large and the decrease in lamp efficiency is large.

When Pxe <80 torr, the lamp efficiency is low, and when Pxe> 350 torr, it becomes difficult to start.

Further, according to the present invention, since Hg is not sealed in the airtight container, use of harmful Hg can be stopped and a highly efficient and long-life lamp can be provided. Further, according to the present invention, since the molecular emission of Na-Xe is high, it is possible to obtain the lamp characteristics according to claim 2 in which the color temperature is 2200K or more and R3 is 50 or more.

In the third aspect of the invention, since the heat insulating member is provided on the inner surface or the outer surface of the airtight container so as to surround the pair of electrodes, the temperature of the airtight container can be kept warm by the heat insulating member. Therefore, it is possible to suppress a decrease in lamp efficiency due to a decrease in airtight container temperature.

In the inventions of claims 4 to 6, since the nitriding modified layer containing nitrogen atoms is formed on at least the inner surface of the airtight container made of translucent alumina ceramics or quartz, the alumina ceramics of the airtight container or It is possible to effectively prevent the reaction between quartz and sodium as a luminescent substance. For this reason, it is possible to effectively prevent the disappearance of sodium as a light emitting substance, and thus it is possible to extend the lamp life without lowering the lamp efficiency. Also,
When the airtight container is made of quartz, the electrode sealing end can be crushed by pinching, so that the airtightness of the electrode sealing end can be improved.

Since the lighting device of the invention according to claim 7 and the lighting device according to claim 8 are equipped with the high-pressure discharge lamp according to any one of claims 1 to 6, the same effects as the high-pressure discharge lamp are obtained. Have.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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 this figure, a high-pressure sodium lamp 1 has a bulb 2 which is an airtight container and a translucent alumina ( For example, it is formed of Al ₂ O ₃ ) ceramics into a closed cylindrical shape, and the cylindrical valve body 2a and both axial end portions 2b and 2c thereof are integrally molded to form a monolithic shape. Through holes 3a and 3b are formed in the central portions of the both ends 2b and 2c, and conductors 4a and 4b made of niobium Nb or an alloy of niobium Nb and zirconium Zr are formed in the through holes 3a and 3b. Is inserted, and this conductor 4a,
4b through glass sealing agents 5a, 5b through holes 3a, 3b
It is airtightly bonded inside.

Electrodes 6a and 6b are welded to the inner ends of the conductors 4a and 4b protruding into the bulb 2. Each electrode 6
a and 6b are electrode shafts 7a made of, for example, tungsten,
Electrode coil 8 made of tungsten is provided at the tip of 7b.
a, 8b are constituted by wound plural times, and these electrodes coils 8a, the 8b, for example, BaO-CaO-WO ₃
The electron emitting material (emitter) such as is coated. This constitutes the arc tube 1A. In addition, an annular strip of molybdenum (M
o) A pair of heat insulating members 9a and 9b made of foil or the like are formed.

When the distance between the pair of electrodes 6a and 6b is L, the inner diameter of the bulb 2 is D, the lamp voltage is V _L , and the lamp power is W _L , the tube wall load W _L / πDL, the lamp For example, the inner diameter D of the valve 2 is reduced so that the current density I _L / π (D / 2) ² , the Xe pressure Pxe, and the potential gradient V _L / L satisfy the following conditional expressions.

[0035]

(Equation 3)

The bulb 2 of the arc tube 1A made of translucent alumina (Al ₂ O ₃ ) ceramics has a nitriding modified layer 10 formed on at least the inner surface thereof. The nitriding reformed layer 10 is made of alumina (Al ₂ O ₃ ) that constitutes the arc tube 2.
Is a layer containing nitrogen atoms having a reaction structure in which is replaced with nitrogen (N ₂ ), and the depth of this layer may be, for example, 0.05 μm or more, and is substantially formed to about 50 μm.

The high-pressure sodium lamp 1 having such a structure
Since the nitrided modified layer 10 is formed on the inner surface of the bulb 2 made of translucent alumina ceramics, it is possible to effectively suppress the reaction of the luminescent substance with sodium and prevent its disappearance. Therefore, it is possible to suppress the decrease of the luminous flux, increase the luminous flux maintenance factor, and reduce the light color change.
Regarding this effect, for example, a high-pressure sodium lamp 1 in which Hg is 5.43 mg, Na is 0.17 mg, and Xe is 25 torr in a bulb 2 having an internal volume of 2.5 cc at a rated power supply voltage for 5.5 hours. On (on) and off for 0.5 hours (o
ff), the lamp voltage change after lighting for 6000 hours was -5.0 to -0.2V, the luminous flux maintenance factor was 97% or more, and the color temperature (Tc) was 2450K or more. Compared with 2500 K at that time, there was almost no change in light color, and the effect of this embodiment was confirmed.

The nitriding reformed layer 10 is a layer having a reaction structure in which the oxygen (O ₂ ) component in the alumina (Al ₂ O ₃ ) forming the bulb 2 is replaced with nitrogen (N ₂ ). Therefore, the structure is inclined in the radial direction, and there is no fear of cracking, peeling, or falling off.

The high-pressure sodium lamp 1 having such a structure
As shown in the specifications of the following Table 1, the inner diameter D of the valve 2 and the distance L between the electrodes are variously changed to make a prototype,
For these prototypes, the initial characteristics after 100 hours of lighting were measured with the lamp voltage V _L as a parameter by controlling the temperature of the coldest part by the heat insulating members 9a and 9b.

[0040]

[Table 1] As a result, when W _L / πDL <14 W / cm ² , the lamp efficiency is drastically reduced, and when W _L / πDL> 20 W / cm ² , the alumina tube or the quartz tube reacts with the enclosed Na to generate Na.
The loss of luminous flux (% lm) was greatly reduced due to the disappearance, and the life was short.

Further, I _L / π (D / 2) ² <10 A / cm
² , the Na-Xe molecular emission was small and _IL / π (D /
2) When ² > 35 A / cm ² , the luminous flux maintenance factor is greatly reduced,
It had a short life.

When V _L / L <15 V / cm, Pxe is low,
The decrease in lamp efficiency is large, and when V _L / L> 25 V / cm, the D-line absorption width is large and the decrease in lamp efficiency is large.

When Pxe <80 torr, the lamp efficiency is small, and when Pxe> 350 torr, it becomes difficult to start.

Further, according to this embodiment, since Hg is not sealed in the airtight container, use of harmful Hg can be stopped and a highly efficient and long-life lamp can be provided. Furthermore, according to this example, since the molecular emission of Na-Xe is high, it is possible to obtain the characteristics that the color temperature is 2200K or higher and the R3 is 50 or higher.

Further, since the heat retaining members 9a and 9b are formed on the outer surface of the valve 2 so as to surround the pair of electrodes 6a and 6b, the temperature of the valve 2 can be retained by the heat retaining members 9a and 9b. . Therefore, it is possible to suppress a decrease in lamp efficiency due to a decrease in temperature of the bulb 2.

The bulb 2 of the arc tube 1A may be a split type alumina ceramic arc tube. In this arc tube, a cylindrical bulb body 2a and axial end portions 2b and 2c thereof are separately formed in advance.
b and 2c are hermetically sealed with a glass sealing agent.

FIG. 2 shows an example of a high-pressure sodium lamp 21 according to the second embodiment of the present invention. This is a high-pressure sodium lamp 1 shown in FIG. It is housed in the outer tube 22 of.

That is, in the high-pressure sodium lamp 21, the outer tube 22 is made of hard glass, a bulging portion is formed in the central portion, and a small diameter top portion 23a and a neck portion 23b are formed in the upper and lower portions thereof, It has a so-called BT shape. A cap 24 is attached to the end of the neck portion 23b.
The inside of the outer tube 22 is kept vacuum.

In the outer tube 22, for example, the arc tube 1 shown in FIG.
The arc tube 1A is accommodated in the outer tube 22 and is supported by a support wire 25 in the outer tube 22. The support wire 25 is formed of a conductive wire such as stainless steel in the shape of a rectangular frame. The upper part is locked in the top part 23 a of the outer tube 22 via the elastic piece 26, and the lower part is the stem. It is welded to one sealing line 28a that is sealed to 27.

One conductor 4a led out from the upper end of the arc tube 1A has an upper conductive holder 29a which also serves as a conductive wire.
Is electrically and mechanically connected to the support wire 25 via. The other conductor 4b led out from the lower end of the arc tube 2 is mechanically supported by another lower holder 29b via a conductive connector 34.

The lower conductor 4b of the arc tube 2 is electrically connected to another sealing wire 28b sealed to the stem 27 through the conductive connector 34 and the lower holder 29b. These sealing lines 28a and 28b are connected to the shell 24a of the base 24 and the eyelet 24b.

On the outer surface of the arc tube 1A, a proximity conductor 31 for assisting the starting is closely arranged 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 connected to the support wire 25. It is supported by the formed locking portion 35. In addition, 32 is a getter.

FIG. 3 shows an illumination device 41 according to the third embodiment of the present invention.
This is housed in the luminaire main body 42 using the high-pressure sodium lamp 21 as a light source. That is, the illuminating device 41 has the reflecting surface 4 on the inner surface of the luminaire main body 42.
It has a housing structure having an opening 2a and a bottom surface or one side surface. Front glass 4 on the bottom of the opening
3 may be provided. A socket 44 is attached to the side wall of the luminaire main body 42, and the base 24 of the high-pressure sodium lamp 21 is screwed into the socket 44 and attached to the luminaire main body 42.

The socket 44 is connected to a commercial power supply 46 via a lighting circuit 45 that is attached to the lighting fixture main body 42 or is provided outside the fixture main body 42 and includes a ballast. The power supply voltage is 200V and the lamp voltage is 100V ± 20V. This lighting circuit 45
Ballast is a dedicated ballast with an igniter that outputs a high voltage pulse for starting.

FIG. 4 shows an example of a high pressure sodium lamp 51 according to the fourth embodiment of the present invention, which is constructed by forming a bulb 52 with a quartz tube so that a pair of electrodes 5 can be formed.
Lead wires 54a, respectively connected to 3a and 53b,
A pair of sealing ends 52a of the valve 52 for sealing 54b,
Since it can be formed by heating and softening 52b and pinching it, the main feature is that the airtightness of each of the sealing end portions 52a and 52b can be enhanced.

In FIG. 4, reference numeral 55 is a nitriding reforming layer, and an appropriate amount of Na and Xe is enclosed in the valve 52 at an appropriate pressure so as to meet the above condition of [Equation 3]. Therefore, it has the same function and effect as the high-pressure sodium lamp 1 made of alumina ceramics.

[0057]

As described above, in each of the first to sixth aspects of the invention, for example, by reducing the tube diameter of the airtight container to a predetermined value, the tube wall load W _L / πDL, the lamp current density I _L / π (D / 2) ² , Xe pressure Pxe, and potential gradient V _L / L are set within the predetermined conditions of [Equation 1], and Na−
The molecular emission of Xe is increased.

When W _L / πDL <14 W / cm ² , the lamp efficiency is drastically reduced, and when W _L / πDL> 20 W / cm ² , the alumina tube or the quartz tube reacts with the encapsulated Na and Na disappears. The luminous flux maintenance factor (% lm) is greatly reduced and the life is short.

I _L / π (D / 2) ² <10 A / cm ² , Na-Xe molecular emission is small, and I _L / π (D / 2) ² >.
At 35 A / cm ² , the luminous flux maintenance factor is greatly reduced and the life is short.

When V _L / L <15 V / cm, Pxe is low,
The decrease in lamp efficiency is large, and when V _L / L> 25 V / cm, the D-line absorption width is large and the decrease in lamp efficiency is large.

When Pxe <80 torr, the lamp efficiency is small, and when Pxe> 350 torr, it becomes difficult to start.

Further, according to the present invention, since Hg is not sealed in the airtight container, use of harmful Hg can be stopped and a highly efficient and long-life lamp can be provided. Further, according to the present invention, since the molecular emission of Na-Xe is high, it is possible to obtain the lamp characteristics according to claim 2 in which the color temperature is 2200K or more and R3 is 50 or more.

In the third aspect of the invention, since the heat insulating member is provided on the inner surface or the outer surface of the airtight container so as to surround the pair of electrodes, the temperature of the airtight container can be kept warm by the heat insulating film. Therefore, it is possible to suppress a decrease in lamp efficiency due to a decrease in airtight container temperature.

In each of the fourth to sixth aspects of the invention, since the nitriding modification layer is formed on at least the inner surface of the airtight container made of translucent alumina ceramics or quartz, the alumina ceramics or quartz of the airtight container and the light emission are formed. It is possible to effectively prevent the reaction of the substance with sodium.
For this reason, it is possible to effectively prevent the disappearance of sodium as a light emitting substance, and thus it is possible to extend the lamp life without lowering the lamp efficiency. Further, when the airtight container is made of quartz, the electrode sealing end can be formed by pinching, so the airtightness of the electrode sealing end can be improved.

Since the lighting device of the seventh aspect of the present invention and the lighting device of the eighth aspect include the high pressure discharge lamp according to any one of the first to sixth aspects, the same effect as the high pressure discharge lamp can be obtained. Have.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a high pressure sodium lamp according to a first embodiment of the present invention.

FIG. 2 is a front view of an example of a high-pressure sodium lamp with an outer tube of a type in which the high-pressure sodium lamp shown in FIG. 1 is built in an outer tube.

FIG. 3 is a configuration diagram of an embodiment of a lighting device and a lighting device according to the present invention.

FIG. 4 is a partially cutaway front view of a high pressure sodium lamp according to another embodiment of the present invention.

[Explanation of symbols]

1, 21 High-pressure sodium lamp (made of translucent alumina ceramics) 1A Arc tube 2 Valve 2a Valve body 2b, 2c Valve end 3a, 3b Pair of through holes 4a, 4b Pair of conductors 6a, 6b Pair of electrodes 9a, 9b A pair of heat insulating films 10 Nitrided modified layer 22 Outer tube 24 Base 25 Support wire 27 Stem 31 Proximity conductor 41 Lighting device 42 Lighting equipment main body 42a Reflective surface 44 Socket 45 Lighting circuit 46 Power supply 51 High pressure sodium lamp (made of quartz)

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

Claims (8)

[Claims] 1. An airtight container in which sodium and xenon are sealed; a pair of electrodes for generating an electric discharge in the airtight container; a distance between the pair of electrodes is L, an inner diameter of the airtight container is D, When the lamp voltage is V _L and the lamp power is W _L , the tube wall load W _L / πDL and the lamp current density I _L / π (D /
2) A high-pressure discharge lamp characterized in that ² , Xe pressure Pxe and potential gradient _VL / L satisfy the following conditions. [Equation 1] 2. The high pressure discharge lamp according to claim 1, which has characteristics of a lamp efficiency of 100 lm / W or more, R3 of 50 or more, and a color temperature of 2200 K or more. 3. The high pressure discharge lamp according to claim 1, wherein a heat insulating member is provided around a pair of electrodes of the airtight container. 4. The high pressure discharge lamp according to claim 1, further comprising a layer containing nitrogen atoms formed on at least the inner surface of the airtight container. . 5. The high pressure discharge lamp according to claim 4, wherein the airtight container is made of translucent alumina ceramics. 6. The high pressure discharge lamp according to claim 4, wherein the airtight container is made of quartz glass. 7. A high-pressure discharge lamp according to claim 1, and a lighting circuit for supplying stable power to the high-pressure discharge lamp by supplying electric power thereto. Lighting device. 8. A lighting device comprising: the high-pressure discharge lamp according to claim 1; and a main body of a fixture that houses the high-pressure discharge lamp.