JP2003163096A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can provide dimmer lighting maintaining good lamp characteristics. <P>SOLUTION: A high pressure discharge lamp 1 has an approximately cylindrically shaped luminous quartz tube 2 in which sodium iodide and scandium as luminous materials are sealed in addition to mercury and argon gas. The luminous quartz tube 2 is disposed in an outer tube 4 and nitrogen is sealed in the outer tube 4. Heat insulating film 3 is disposed near electrodes disposed in the luminous tube 2. Good dimmer lighting of prescribed luminous flux or more can be realized at rating life time of the lamp by using the discharge lamp lighting device on which a lamp stabilizer is installed, which detects the maximum value or the minimum value of derivative waveform of the lamp voltage and supplies the high pressure discharge lamp 1 the same power as the power that is supplied to the high pressure discharge lamp 1 just before fluctuation of the lamp voltage occurs. <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 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. Further, in the field of high pressure discharge lamps, JP-A-6-8
As shown in Japanese Laid-Open Publication No. 4496, research and development are actively conducted.

[0006]

However, in the metal halide lamp lighting device which is one of the discharge lamp lighting devices,
There was a concern that the life of the lamp would be impaired if the lamp was dimmed by supplying less than the rated power to the lamp. In the U.S.A., ballasts for metal halide lamps that are already equipped with dimming lighting means are on the market, but in order to secure the lamp life, the lamp power during dimming lighting should be 50% or more of the rated lamp power, and It is generally accepted that the lamp will be lit at rated power for at least 15 minutes at startup.

However, since the grounds for this view are not always clear, some lamp manufacturers have their own lighting time of 10 minutes at the rated power at the time of starting.

Further, generally, the dimming ratio indicating the ratio of the lamp power to the rated lamp power at the time of dimming is often determined in consideration of the energy saving rate and the cost rather than the travel characteristic of the lamp.

The present invention has been made in view of the above problems, and an object thereof is to provide a discharge lamp lighting device capable of maintaining dimming lighting while maintaining good discharge lamp characteristics. To do.

[0010]

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 lighting device having an electric lamp and control means for controlling lighting of the discharge lamp, wherein the control means performs lighting control with less power than the rated power of the discharge lamp. It is a thing. This allows the discharge lamp characteristics,
In particular, it is possible to suppress an adverse effect on the luminous flux maintenance factor.

Further, a dimming means for dimming the discharge lamp may be provided, and the characteristic of the discharge lamp during lighting may be discriminated and the dimming lower limit may be set.

Further, as the characteristic of the discharge lamp, the change of the discharge lamp voltage may be determined.

The change in the discharge lamp voltage may be determined by determining the change in the differential value of the discharge lamp voltage.

Further, as the characteristic of the discharge lamp, the change of the discharge lamp voltage and the discharge lamp current may be judged.

The change of the discharge lamp voltage and the discharge lamp current may be judged by the change of the phase difference between the discharge lamp voltage and the discharge lamp current.

Further, the change of the discharge lamp voltage and the discharge lamp current may be judged by the change of the discharge lamp current with respect to the discharge lamp voltage.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION It is considered that the cause of a decrease in lamp life when dimming lighting of a high pressure discharge lamp is caused by electrodes. Usually, the electrode temperature of the high pressure discharge lamp is designed to be in a temperature range in which thermoelectrons can be sufficiently emitted at the cathode when the lamp is lit with the rated lamp power. But,
If the electrode temperature falls too low due to the dimming lighting, electron emission from the cathode becomes insufficient as shown below.

The relationship between the thermionic emission current density J at the cathode and the absolute temperature T of the electrode is as follows: Richardson-Dashman equation when an external electric field E is applied, J = AT ² exp {-φ / kT + (e / ² kT) · (eE / πε ₀ ) ^1/2 } (1) Where A is a constant that depends on the material and surface condition of the electrode, φ is the work function of the electrode,
k is the Boltzmann constant, e is the elementary charge, and ε ₀ is the dielectric constant of vacuum.

In the equation (1), the external electric field E is small,
It is assumed that the second term of the exponent part of equation (1) can be ignored compared to the first term. At this time, in order to obtain the required current density J, there is a threshold value To at which the thermoelectrons can be emitted at the electrode temperature. If T> To, the current required to light the lamp can be easily discharged.
It can be seen that <To is substantially J = 0. Therefore,
If the electric power supplied to the lamp is lowered too much, the electrode temperature falls from the lower limit To of the appropriate temperature range, and thermionic emission at the cathode becomes insufficient.

In fact, even when the electrode temperature drops below To, the electric field E (cathode drop voltage) in the vicinity of the cathode is intensified, and the second term of the exponent part of the formula (1) becomes large (Schottky. Due to the increase of the effect), J = 0 is not immediately obtained. Further, when the electric field E is strengthened, there is a possibility that electrons are supplied from the cathode by the field electron emission mechanism in addition to the thermoelectron emission mechanism. Therefore, even if the electrode temperature falls below To, the discharge is maintained to some extent. It is thought to be done. However, on the other hand, it is considered that the probability of the electrode material scattering (sputtering) due to the impact of ions increases as the cathode drop voltage increases.

Therefore, when the lamp is lit in the state where the electrode temperature is lower than To, the arc tube may be blackened at an early stage, and the luminous flux maintenance factor may be lowered as compared with the case where only the rated lamp power is lit. To be worried. In addition, since blackening of the arc tube causes the temperature of the arc tube to rise during lighting, a rise in the lamp voltage and an increase in the impurity gas concentration inside the arc tube occur earlier than in the case of lighting only with the rated lamp power. However, there is a concern that the lamp life may be shortened due to the early non-lighting of the lamp.

In the United States, the lamp power during dimming lighting is equal to the rated lamp power in order to prevent the lamp life from being adversely affected.
It is considered that the general view that it is set to 50% or more is due to the above reason. However, it is difficult to think that the temperature range of electric power that can emit thermoelectrons is 50% or more of the rated lamp electric power regardless of the lamp of any manufacturer.
The rationale for the value of% is unclear. Therefore, the following dimming lighting experiment was carried out in order to obtain the dimming lighting lower limit value that would be different for each lamp and does not adversely affect the lamp life.

(Embodiment 1) FIG. 1 is a schematic view showing an example of a high pressure discharge lamp according to the present invention. 1 is a high-pressure discharge lamp, rated lamp power 400 W, arc tube inner diameter 23 mm, electrode distance 40 m
This is a metal halide lamp in which, in addition to mercury and argon gas, scandium and sodium iodide as light emitting substances are enclosed in a quartz arc tube 2 formed in a substantially cylindrical shape of m. The arc tube 2 is arranged in an outer tube 4, and nitrogen is enclosed in the outer tube 4. The heat insulating film 3 is arranged near the electrodes arranged in the arc tube 2.

The high pressure discharge lamp 1 is connected to a commercial power source through a pulse generator 5 shown in FIG. 2 and a dimming ballast 6 capable of changing lamp power by changing impedance. The following four types of lamps are used in this embodiment.

With reference to the lamp A, the lamp B is the arc tube 2
It is a lamp with a diameter of 8 mm and an arc tube inner diameter of 15 mm. The lamp C is a lamp in which the heat insulating film 3 applied near the sealing portion of the arc tube 2 is peeled off. Lamp D is a lamp in which iodide of indium, thallium, and sodium is enclosed as a light emitting substance.

In such a lamp and discharge lamp lighting device, 1) rated lamp power 2) 60% of rated lamp power 3) 50% of rated lamp power 4) 40% of rated lamp power 5) 30% of rated lamp power A lighting experiment was conducted with a lamp power of%.

The results are shown in FIG. The ● mark in the table indicates that the specified luminous flux value was obtained at the rated life of the lamp.
The mark indicates that the specified luminous flux value was not obtained at the rated lamp life, that is, the rated lamp life was deteriorated. Also,
The part marked with a double circle indicates that a luminous flux higher than the specified luminous flux was obtained during the rated life of the lamp.

Conventionally, there was a fear that the rated life of the lamp would be shortened if the dimming lighting is performed. However, as a result of experiments, it was discovered that there is a lamp that exhibits a better luminous flux maintenance rate than when the lamp is lit at the rated lamp power. That the luminous flux higher than the specified luminous flux value is obtained during the rated lamp life is, in other words, equivalent to the extended lamp rated life.

According to the results shown in FIG. 3, the lower limit of the lamp power (the lamp power changing from the ● mark to the × mark) at which the specified luminous flux value is obtained at the rated lamp life varies depending on the lamp, and is uniformly 50%. This indicates that in the conventional lighting device that performs dimming lighting with electric power or 25% lamp power, some lamps have a luminous flux maintenance factor below the specified value at the rated lamp life.

However, as a result of analyzing the data obtained by this experiment, it was found that there is a certain tendency in the change of the maximum value or the minimum value of the differential waveform of the lamp voltage. Here, the lamp voltage / lamp current waveforms are shown in FIG. 4, and the changes in the differential waveform of the lamp voltage are shown in FIGS. 5 and 6. As shown in FIG. 5, when the lamp power is reduced from the rated lamp power, the maximum value or the minimum value of the differential waveform of the lamp voltage becomes almost the same value up to a certain lamp power. However, as shown in FIG. 6, when the lamp power is further reduced, the maximum value or the minimum value of the differential waveform of the lamp voltage starts to change. The lamp power at which the maximum value or the minimum value of the differential waveform of the lamp voltage suddenly changes and the lamp power at which the specified luminous flux value cannot be obtained at the rated lamp life shown in Fig. 3 are the types of lamp. There was a good agreement regardless of. That is, it was discovered that the lamp power value immediately before the maximum value or the minimum value of the differential waveform of the lamp voltage starts to change is the lower limit value of the dimming lighting for the lamp to obtain the specified luminous flux value at the rated lamp life. is there.

In order to confirm the validity of the present invention, a lamp ballast 5 capable of detecting the fluctuation of the maximum value or the minimum value of the differential waveform of the lamp voltage and supplying the lamp power to the lamp immediately before the fluctuation occurs. A discharge lamp lighting device was built in, and a lighting experiment was conducted.

As a result, 95% or more of the tested lamps were able to obtain a luminous flux value equal to or higher than the specified luminous flux value at the rated lamp life. On the other hand, a lamp lit by a lighting device incorporating a lamp ballast 5 capable of supplying the lamp with a lamp power lower than the lamp power at which the maximum value or the minimum value of the differential waveform of the lamp voltage fluctuates, 90% or more could not obtain the specified luminous flux value at the rated lamp life.

As described above, the discharge lamp lighting device incorporating the lamp ballast capable of detecting the fluctuation of the maximum value or the minimum value of the differential waveform of the lamp voltage and supplying the lamp electric power immediately before the fluctuation occurs to the lamp. By using
It is possible to realize excellent dimming lighting in which a specified luminous flux value or a luminous flux value higher than the prescribed value can be obtained during the rated lamp life.

(Embodiment 2) Further, in addition to the method of detecting the variation of the maximum value of the differential waveform of the lamp voltage described in Embodiment 1, good dimming that at least a specified luminous flux value can be obtained at the rated lamp life. Since a characteristic change that serves as an index that can realize lighting is found, it will be described below.

As a result of analyzing the data obtained by the experiment described in Example 1, the lamp power at which the phase difference between the lamp voltage and the lamp current begins to change and the lamp power at which the specified luminous flux value cannot be obtained at the rated life. There was a good agreement with and regardless of lamp type. The phase difference between the lamp voltage and the lamp current can be quantitatively expressed by “lamp power factor: cos θ = W / (V × I)”. In the above equation, cos θ
Is the lamp power factor, W is the lamp power, V is the lamp voltage, and I is the lamp current. FIG. 7 shows the lamp power factor characteristic of the lamp C with respect to the lamp power as an example of the lamp that was tested. As shown by the solid and dotted arrows in the figure, the power factor changed significantly between 200W, which is 50% lamp power, and 160W, which is 40% lamp power, which is consistent with the results shown in Fig. 3. There is. That is, it was discovered that the lamp power value immediately before the lamp power factor started to change was the lower limit value of the dimming lighting for which the specified luminous flux value was obtained at the rated lamp life.

In order to confirm the validity of the present invention, a discharge lamp lighting device incorporating a lamp ballast capable of detecting a fluctuation in the lamp power factor and supplying the lamp power immediately before the fluctuation occurs is prepared. Then, the lighting experiment was conducted. As a result, 93% or more of the tested lamps were able to obtain a luminous flux value equal to or higher than the specified luminous flux value at the rated lamp life. On the other hand, 92% or more of the lamps lit by a discharge lamp lighting device that incorporates a lamp ballast that can supply a lamp power that is lower than the lamp power that causes fluctuations in the lamp power factor The specified luminous flux value could not be obtained at the end of life.

Therefore, a discharge lamp lighting device incorporating a lamp ballast capable of detecting a fluctuation in the lamp power factor (= phase difference between the lamp voltage and the lamp current) and supplying the lamp power immediately before the fluctuation occurs to the lamp. By using, it is possible to realize good dimming lighting in which a prescribed luminous flux value or a luminous flux value higher than the prescribed value is obtained at the rated life of the lamp.

(Embodiment 3) As yet another example, in addition to the methods described in Embodiments 1 and 2, good dimming lighting is realized in which at least a specified luminous flux value is obtained during the rated life of the lamp. Since a characteristic change that can be used as an index has been found, it will be described below.

The characteristics obtained by plotting the changes in the lamp voltage and the lamp current with respect to time with the lamp voltage as the horizontal axis and the lamp current as the vertical axis are generally called a Lissajous waveform. The Lissajous waveform drawn based on the lamp voltage / lamp current characteristics (FIG. 4) with respect to time obtained by the experiment described in Example 1 is shown in FIG. Is shown in FIG. The maximum or minimum value of the lamp current in the Lissajous waveform decreases with decreasing lamp power. The direction in which the maximum or minimum value of the lamp current moves as the lamp power decreases is
It moved in a substantially straight line up to a certain lamp power (the movement of the maximum value is shown by a solid arrow in FIG. 9). However, it has been found that the direction in which the maximum value or the minimum value of the lamp current moves changes below a certain electric power (the movement of the maximum value is indicated by a chained arrow in FIG. 9). A good agreement was found between the lamp power at which the maximum value or the minimum value of the lamp current started to change and the lamp power at which the specified luminous flux value could not be obtained during the rated lamp life, regardless of the type of the lamp.

That is, the lamp electric power value immediately before the moving direction of the maximum value or the minimum value of the lamp current in the Lissajous waveform is changed is the lower limit value of the dimming lighting for which the specified luminous flux value is obtained at the rated life of the lamp. Was discovered.

In order to confirm the validity of the present invention, it is possible to detect a fluctuation in the direction in which the maximum value or the minimum value of the lamp current in the Lissajous waveform moves and supply the lamp power to the lamp immediately before the fluctuation occurs. A lighting device incorporating a ballast was created and a lighting experiment was conducted. as a result,
More than 95% of the tested lamps were able to obtain a luminous flux value equal to or higher than the specified luminous flux value at the rated lamp life.
On the other hand, the discharge lamp lighting device incorporates a lamp ballast that can supply the lamp with a lower lamp power than the lamp power at which the maximum or minimum value of the Lissajous waveform fluctuates in the moving direction. In the lamps subjected to the above, 95% or more could not obtain the specified luminous flux value at the rated lamp life.

Therefore, the discharge lamp lighting incorporating the lamp ballast capable of detecting the fluctuation in the moving direction of the maximum value or the minimum value of the lamp current in the Lissajous waveform and supplying the lamp power with the lamp power immediately before the fluctuation occurs. By using the device, it is possible to realize good dimming lighting in which a prescribed luminous flux value or a luminous flux value higher than the prescribed value can be obtained at the rated lamp life.

It should be noted that Examples 1 to 3 are given as examples only, and, for example, the shapes of arc tubes and electrodes,
The parts other than those related to the essence of the present invention, such as the type and amount of the enclosed material, the presence / absence of the starter in the discharge lamp, the rated lamp power value, and the output waveform of the ballast, are limited to the above embodiment. Not to mention it.

[0044]

According to the present invention, by determining the discharge lamp characteristics during lighting and setting the dimming lower limit, it is possible to suppress adverse effects on the discharge lamp characteristics, particularly the luminous flux maintenance factor,
It was possible to provide 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 block diagram of a high pressure discharge lamp and a discharge lamp lighting device according to the present invention.

FIG. 3 is a table showing the luminous flux maintenance characteristics at the rated lamp life with respect to the lamp power according to the present invention.

FIG. 4 is a lamp voltage and lamp current waveform diagram according to the present invention.

FIG. 5 is a differential waveform diagram of the lamp voltage according to the first embodiment of the present invention.

FIG. 6 is a differential waveform diagram of the lamp voltage according to the first embodiment of the present invention.

FIG. 7 is a lamp power factor characteristic diagram according to the second embodiment of the present invention.

FIG. 8 is a Lissajous waveform diagram according to the third embodiment of the present invention.

FIG. 9 is a partial enlarged view of a Lissajous waveform according to the third embodiment of the present invention.

[Explanation of symbols]

1 High-pressure discharge lamp 2 arc tube 3 insulation film 4 outer tube 5 pulse ballast 6 pulse generator

   ─────────────────────────────────────────────────── ─── 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) 3K082 AA35 AA51 AA57 AA61 BA04                       BA24 BA31 BA58 BC23 BD03                       BD04 BD05 BD26 BD32 CA33                       CA36                 3K098 CC24 CC40 CC49 CC70 DD06                       DD18 DD20 DD43 EE33 FF03                       FF04 FF14 FF20

Claims (7)

[Claims] 1. A discharge lamp in which at least mercury and a rare gas are sealed in a transparent container in which electrodes are hermetically sealed.
A discharge lamp lighting device having a control means for controlling lighting of the discharge lamp, wherein the control means performs lighting control with less power than the rated power of the discharge lamp. apparatus. 2. The discharge lamp according to claim 1, further comprising a dimming unit for dimming the discharge lamp, determining a characteristic of the discharge lamp during lighting, and setting a dimming lower limit. Lighting device. 3. The discharge lamp lighting device according to claim 2, wherein a change in discharge lamp voltage is determined as a characteristic of the discharge lamp. 4. The discharge lamp lighting device according to claim 3, wherein the change of the discharge lamp voltage is determined by a change of a differential value of the discharge lamp voltage. 5. The discharge lamp lighting device according to claim 2, wherein a change in a discharge lamp voltage and a change in a discharge lamp current is determined as a characteristic of the discharge lamp. 6. The discharge lamp lighting according to claim 5, wherein the change in the discharge lamp voltage and the discharge lamp current is determined by a change in the phase difference between the discharge lamp voltage and the discharge lamp current. apparatus. 7. The discharge lamp lighting device according to claim 5, wherein the change in the discharge lamp voltage and the discharge lamp current is determined by a change in the discharge lamp current with respect to the discharge lamp voltage.