JP2003162980A - Discharge lamp and lighting device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp and lighting device for the discharge lamp which sustain better lamp characteristics and are capable of controlling the lighting. <P>SOLUTION: Fig. 1 shows a light emitting tube, and electrodes 2 are sealed to sealing parts 5 of the both ends. Within the light emitting tube 1, mercury and argon gas, and an iodide of sodium and scandium as a light emitting material are sealed. The light emitting tube 1 is retained in an outer tube by a support 4 for the light emitting tube connected to a stem fused to the outer tube 3. The electrodes 2 comprise an electrode center bars 2a and coils 2b, an end of the electrode center bars 2a is connected to an end of a metal foil conductor 6 in the sealing parts, and the other end of the metal foil conductor 6 is connected to an electrode lead wire 7, while the other end of the electrode lead wire 7 is connected to the support 4 for the light emitting tube. Fig. 8 indicates a base and is electrically connected to the electrodes 2 via the stem, the support 4 for the light emitting tube, the electrode lead wire 7 and the metal foil conductor 6. The above discharge lamp can be useful for flicker of the discharge lamp by meeting a lamp power W≥17.7×EXP (3.4 × an area S of the electrode end). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp and a discharge lamp lighting device.

[0002]

2. Description of the Related Art A general high pressure discharge lamp is provided with a pair of electrodes in an arc tube made of a translucent material so that the inside is kept airtight, and a rare gas for starting the discharge lamp. And mercury, which acts as a buffer gas to maintain the voltage of the discharge lamp. In the case of a metal halide lamp, a metal halide is further enclosed, and in the case of a high-pressure sodium lamp, metallic sodium is enclosed.

One end of the electrode is sealed by a pinch seal or a frit so as to keep the arc tube airtight, is led out to the outside, and is connected to a power source through a starter, a ballast and the like. Then, a voltage is applied between the pair of electrodes to generate a discharge, and the heat of the generated discharge causes the enclosed metal to evaporate and be excited in the discharge space to emit a predetermined light.

These high-pressure discharge lamps are used in a wide range of fields because they have characteristics such as high brightness and high efficiency, and have been expanded in variety of light colors and light amounts and downsized. Further, recently, research and development have been promoted from the viewpoint of protecting the global environment, and reduction of the amount of use of mercury, which is a harmful substance, prolongation of life of lamps, energy saving, and the like.

One of them is research and development of so-called dimming lighting, in which the light output is freely changed by changing the input to the lamp, and a large amount of light can be obtained by increasing the input when necessary. When a large amount of light is not needed, the input can be narrowed down to reduce the amount of power used to save energy, which has already been put to practical use in fluorescent lamps and the like.

However, the dimming lighting of high pressure discharge lamps has been delayed in practical use except for some mercury lamps and high pressure sodium lamps. Dimming lighting of high-pressure discharge lamp is “flickering occurrence”,
This is because problems such as “light flux reduction due to blackening and devitrification promotion”, “occurrence of extinction”, and “light color change” are more likely to occur than in rated lighting in which lighting is performed only with predetermined power.

In describing the present invention, the discharge mechanism of the high pressure discharge lamp will first be briefly described below. When the power is turned on, a voltage is applied between the electrodes to generate an electric field. Electrons accelerated by this electric field collide with gas atoms and ionize them, so that secondary electrons are extracted from the cathode and a current rapidly flows. As the current increases, the Joule loss of the electrode increases, the cathode is heated, the cathode bright spot is formed, and thermionic emission is performed. Then, the lamp voltage suddenly drops and the arc discharge is started.
After that, electrons are supplied from the cathode by thermionic emission and field emission, and the discharge is maintained.

Generally, in a high pressure discharge lamp, electrons are mainly supplied by thermoelectron emission, and the ratio of electrons by field emission is small. The electrodes of the high-pressure discharge lamp are designed to balance the heating of the electrodes with the rated lamp current and the temperature drop due to heat dissipation from the electrodes so that the temperature at which the electrons required for discharge are constantly supplied is maintained. ing.

[0009]

If this temperature balance is lost for some reason, damage to the electrodes will be accelerated,
It adversely affects the lamp. For example, if the input energy is increased too much, the temperature of the electrode rises and the evaporation of the electrode becomes vigorous, so that the blackening of the arc tube progresses and the service life deteriorates. On the other hand, if the input energy is reduced too much, the electrode temperature drops, and it becomes difficult to maintain stable discharge only by supplying electrons by thermionic emission. Then, the cathode drop voltage rises in order to maintain the discharge, and an electrode bright spot is formed. Electrode bright spots are formed at locations where the electric field due to the cathode drop voltage is most likely to be concentrated. The place where the electric field is most likely to concentrate is not constant because it changes depending on the condition of the electrode surface, temperature, and the like. Therefore, the electrode bright spots move. When the movement of the electrode bright spots becomes intense, it is observed as "flicker of discharge".

When the electrode temperature is further lowered, a higher temperature is required to maintain the discharge. In order to obtain the required temperature, the electric field becomes stronger and the size of the electrode bright spot (area of the bright spot on the electrode surface) becomes smaller. For this reason, the temperature of the part where the bright spot is generated becomes higher, but the temperature of the other part of the electrode is further lowered by radiation and conduction, so that the temperature for maintaining the discharge cannot be obtained and the bright spot cannot be formed. That is, the discharge cannot be maintained and the lamp goes out. The phenomenon that the lamp temperature goes off due to a decrease in the electrode temperature due to the reduction of the input energy due to the dimming lighting is called "extinguishing during dimming".

A flicker-producing lamp is not suitable for illuminating a space such as a commercial space where high quality light is required. However, the lamp does not turn off immediately when flicker occurs. There is also an application in which power reduction is prioritized if there is a flicker that is not felt by humans even if the electrode bright spots move. On the other hand, the occurrence of extinction during dimming is not suitable for any application because the lamp goes out.

Efforts to avoid such problems and obtain a stable discharge are being actively carried out in various places, but the present situation is that the design guideline has not yet been sufficiently established.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high pressure discharge lamp and a high pressure discharge lamp capable of dimming lighting that can obtain a stable discharge until the end of its life. An object is to provide an electric lamp lighting device.

[0014]

In order to solve the above problems, according to the present invention, at least mercury and a rare gas are sealed in a transparent container in which electrodes are hermetically sealed. A discharge lamp, the cross-sectional area S (mm ² ) of the tip of the electrode,
When the discharge lamp power is W (W), W ≧ 39.6 × EXP (2.8 ×
S) is satisfied. This reduces the occurrence of flickering due to dimming lighting,
Stable dimming lighting can be performed.

A discharge lamp in which at least mercury and a rare gas are enclosed in a light-transmissive container in which electrodes are hermetically sealed, wherein a cross-sectional area S (mm ² ) of a tip portion of the electrode is emitted. In the case of the electric power W (W), W ≧ 17.7 × EXP (3.4 × S) is satisfied. This allows
Stable dimming lighting can be performed by reducing the occurrence of fading due to dimming lighting.

By satisfying W ≦ 537.4 × EXP (−0.2 × S), a predetermined luminous flux can be obtained at the end of life.

Further, the cross-sectional area S (mm ² ) of the tip of the electrode is
However, it is preferable that 0.2 ≦ S ≦ 0.8 is satisfied.

The present invention can also be applied to the case where the discharge lamp is a metal halide lamp containing a metal halide.

[0019]

1 is a schematic diagram showing an example of a high pressure discharge lamp according to the present invention. Reference numeral 1 denotes an arc tube made of quartz glass, and electrodes 2 are sealed to the sealing portions 5 at both ends. The arc tube 1 is formed in a substantially cylindrical shape having an inner diameter of 20 mm and a distance between electrodes of 35 mm. The arc tube 1 is filled with mercury, argon gas, and sodium and scandium iodide as a light emitting substance. The arc tube 1 is held inside the outer tube by an arc tube support 4 connected to a stem welded to the outer tube 3. A getter (not shown) is attached to the arc tube support 4. The electrode 2 is composed of an electrode mandrel 2a and a coil 2b, and one end of the electrode mandrel 2a is connected to one end of the metal foil conductor 6 in the sealed portion. The other end of the metal foil conductor 6 is connected to the electrode introduction line 7, and the other end of the electrode introduction line 7 is connected to the arc tube support 4. A heat insulating film made of zirconium oxide or the like is formed on a part of the arc tube from the electrode sealing portion. Then, nitrogen is enclosed in the outer tube. 8
Is a base and is electrically connected to the electrode 2 via the stem, the arc tube support 4, the electrode lead-in wire 7, and the metal foil conductor 6. The illustrated high pressure discharge lamp is connected to a commercial power source (not shown) via a pulse generator (not shown) capable of varying the input energy to the pulse generator and the pulse required for starting.

In the lamp having the above-mentioned structure, experiments were conducted by changing the dimensions of the electrode mandrel 2a and the coil 2b. As a result, it has been found that the characteristics such as flicker and extinction are less affected by the size of the coil 2b and largely depend on the cross-sectional area of the tip of the electrode mandrel 2a. Therefore, the description will be made below based on the dimensions of the electrode mandrel 2a. FIG. 2 is a table showing the diameter of the electrode mandrel 2a of the lamp used in the experiment of the present embodiment and the cross-sectional area of the tip of the electrode.

These lamps having the dimensions shown in FIG. 2 were turned on, and after the electric characteristics and light characteristics of the lamp were sufficiently stabilized, the state of discharge was observed while reducing the input lamp power. The ramp power reduction rate is 10W each,
In the region where the discharge becomes unstable, the number of steps is set smaller. Further, each time the lamp power was lowered, the lamp was held until the electric characteristics of the lamp were sufficiently stabilized. FIG. 3 shows the observation result of the discharge thus obtained when the lamp power was changed. FIG. 3 shows the state of discharge with the horizontal axis representing the cross-sectional area of the electrode tip and the vertical axis representing the lamp power.

For example, the discharge of a lamp made of an electrode having an electrode diameter of 0.5 mm and a cross-sectional area of the electrode tip portion of about 0.20 mm ² was stable at a lamp power of 400 W or 250 W. However, when the input power was further reduced, electrode bright spots began to form on the electrode surface from around 80 W, and flicker was observed. Moreover, when the input power was further reduced, the extinction occurred at 40W.

Similarly, the lamp discharge made with an electrode having an electrode diameter of 0.75 mm and a cross-sectional area of the electrode tip portion of about 0.44 mm ² was stable from 450 W to about 150 W of lamp power. As the input power was further reduced, electrode bright spots began to form on the electrode surface from around 120 W, and flicker was observed. Moreover, when the input power was further reduced, it disappeared at 72W.

Furthermore, the discharge of a lamp made with an electrode having an electrode diameter of 1.00 mm and a cross-sectional area of the electrode tip portion of about 0.79 mm ² was stable at a lamp power of 400 W, but from the vicinity of 360 W the electrode was discharged. Electrode bright spots began to appear on the surface and disappeared at 260W.

As a result of these observations, it was found that, in the relationship between the lamp power and the cross-sectional area of the electrode tip, flicker occurs when light control is performed up to the lamp power shown by the solid line in FIG. The solid line in FIG. 3 is represented by the following approximate expression.
Here, W represents the lamp power (W), and S represents the electrode tip cross-sectional area (mm ² ). W = 39.6 × EXP (2.8 × S) That is, it has been found that flicker can be prevented in a region where the relation of W ≧ 39.6 × EXP (2.8 × S) holds.

Further, it has been discovered that dimming is prevented when light control is performed up to the ramp power shown by the chain line in FIG. The chain line in FIG. 3 is represented by the following approximate expression. W = 17.7 × EXP (3.4 × S) That is, it was found that the extinction can be prevented in the region where the relation W ≧ 17.7 × EXP (3.4 × S) holds.

Next, FIG. 4 additionally shows the result of a life test performed on the lamp shown in FIG. 2 in FIG. For example, a lamp made with an electrode having an electrode diameter of 0.50 mm and a cross-sectional area of the electrode tip section of approximately 0.20 mm ² has a rated black life due to severe blackening when subjected to a life test with a lamp power of 500 W or more. The luminous flux value at that time has fallen below the default value.

Similarly, a lamp made of an electrode having an electrode diameter of 0.96 mm and a cross-sectional area of the electrode tip portion of about 0.72 mm ² has 4
When a life test was performed with a lamp power of 50 W or more, blackening was intense and the luminous flux value at the rated life was below the default value.

As a result of these observations, in relation to the lamp power with respect to the cross-sectional area of the electrode tip portion, the lamp lit beyond the lamp power shown by the one-dot chain line in FIG. It was found that the luminous flux value was below the default value. The alternate long and short dash line in FIG. 4 is represented by the following approximate expression. W = 537.4 × EXP (−0.2 × S) That is, in the region where the relation W ≦ 537.4 × EXP (−0.2 × S) holds, it was discovered that the specified luminous flux value can be maintained until the rated life.

In the above-mentioned embodiment, the above-mentioned embodiments have been described with reference to the metal halide lamp in which scandium and sodium iodide are enclosed.
Similar results could be confirmed in a high-pressure mercury lamp in which only a metal halide was enclosed without containing a metal halide.

The relational expressions thus found serve as a guideline for designing electrodes of a high-pressure discharge lamp that performs dimming lighting. For example,
It can be seen that when an electrode with an electrode tip cross section of 0.38 mm ² (electrode diameter 0.7 mm) is used, stable lighting can be achieved up to about 110 W without flicker. At the same time, it can be seen that if it is 500 W or less, the specified luminous flux can be obtained until the rated life. That is, a lamp using an electrode (electrode diameter 0.7 mm) having a cross-sectional area of the electrode tip portion of 0.38 mm ² can realize dimming lighting from 500 W to 110 W without flicker.

As another example, a 400 W rated lamp is
If you want to use and without dimming flickering to 25%, by obtaining the point of intersection is the solid line in Ranfu ° power 100W and 4, the cross-sectional area electrode tip when fix the electrode diameter of about 0.33 mm ² in 0.65mm I know there is. Therefore, if an electrode thinner than 0.65 mm is used,
It turns out that a 400W rated lamp can be used to dim up to 25% without flicker.

Similarly, for example, when it is desired to use a lamp rated at 400 W up to 25% without dimming, the electrode tip can be obtained by finding the intersection of the lamp power of 100 W and the chain line in FIG. The sectional area is about 0.51 mm ²
It can be seen that it is 0.81 mm. Therefore, it is clear that if an electrode thinner than 0.81 mm is used, a lamp rated at 400 W can be used for dimming up to 25% without dimming.

[0034]

According to the present invention, there is provided a discharge lamp in which at least mercury and a rare gas are enclosed in a light-transmissive container in which electrodes are hermetically sealed. S
(Mm ² ) and discharge lamp power W (W), W ≧ 39.6 × EXP
It is characterized by satisfying (2.8 × S). As a result, the occurrence of flickering due to dimming lighting can be reduced, and stable dimming lighting can be performed.

A discharge lamp in which at least mercury and a rare gas are enclosed in a light-transmissive container in which electrodes are hermetically sealed, wherein a cross-sectional area S (mm ² ) of a tip portion of the electrode is emitted. In the case of the electric power W (W), W ≧ 17.7 × EXP (3.4 × S) is satisfied. This allows
Stable dimming lighting can be performed by reducing the occurrence of fading due to dimming lighting.

By satisfying W ≦ 537.4 × EXP (−0.2 × S), a predetermined luminous flux can be obtained at the end of life.

Therefore, it was possible to provide a discharge lamp and a discharge lamp lighting device capable of performing dimming lighting while maintaining good lamp characteristics.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a high pressure discharge lamp according to the present invention.

FIG. 2 is a table showing the diameter of the electrode mandrel and the cross-sectional area of the tip of the electrode of the lamp according to the present invention.

FIG. 3 is a diagram showing a relationship between a lamp power in which flicker and extinguishment occur, with respect to an electrode tip end cross-sectional area according to the present invention.

FIG. 4 is a diagram showing a relationship between lamp powers for obtaining a predetermined luminous flux value at the rated life according to the present invention.

[Explanation of symbols]

1 High-pressure discharge lamp 2 electrodes 2a Electrode mandrel 2b coil 3 outer tube 4 arc tube support 5 Sealing part 6 Metal foil conductor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takuma Hashimoto             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Koji Nishioka             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Kazuhiko Sakai             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company F term (reference) 5C039 HH05 HH07

Claims (6)

[Claims] 1. A discharge lamp in which at least mercury and a rare gas are enclosed in a light-transmissive container in which an electrode is hermetically sealed, wherein a tip cross-sectional area S (mm ² ) of the electrode is emitted. A discharge lamp characterized by satisfying W ≧ 39.6 × EXP (2.8 × S) in the case of electric power W (W). 2. A discharge lamp in which at least mercury and a rare gas are enclosed in a light-transmissive container in which an electrode is hermetically sealed, wherein a cross-sectional area S (mm ² ) of a tip portion of the electrode is emitted. A discharge lamp characterized by satisfying W ≧ 17.7 × EXP (3.4 × S) in the case of electric power W (W). 3. The discharge lamp according to claim 1, wherein W ≦ 537.4 × EXP (−0.2 × S) is satisfied. 4. The cross-sectional area S (mm ² ) of the tip of the electrode
The discharge lamp according to any one of claims 1 to 3, wherein 0.2 ≦ S ≦ 0.8 is satisfied. 5. The discharge lamp according to any one of claims 1 to 4, wherein the container contains a metal halide. 6. The discharge lamp according to any one of claims 1 to 5, and control means for controlling lighting of the discharge lamp, wherein the control means varies electric power input to the discharge lamp. A discharge lamp lighting device characterized by the above.