JPH11265798A - Discharge lamp lighting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting control method specified for a rare gas discharge lamp, and to maximize ultraviolet radiation efficiency and visible radiation efficiency through a fluorescent material. SOLUTION: In this lighting method, negative pulse voltage is impressed on transparent conductive film during the better part of time from before to after the rise of voltage pulse width impressed on both ends of a low-voltage discharge lamp 7, using the transparent conductive film loaded to a bulb of the low-voltage discharge lamp 7 and lamp bulb impressed pulse generator 9 impressing electric potential on the transparent conductive film. That is, maximization of visible radiation efficiency is realized by optimizing the impressed pulse voltage/current of the rare gas fluorescent lamp, pulse frequency, a pulse time interval, and the pulse voltage/pulse timing of the lamp bulb impressed pulse.

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 method capable of realizing highly efficient ultraviolet light emission and lighting a low pressure discharge lamp with high efficiency.

[0002]

2. Description of the Related Art Among low-pressure discharge lamps, discharge lamps filled with a mixed rare gas, that is, rare gas discharge lamps, have much lower luminous efficiency than lamps filled with mercury. However, the advantage of this rare gas discharge lamp is that it does not have the remarkable temperature characteristics which are a drawback of the mercury filled lamp.

For this reason, it is often used as a light source for information reading such as a copying machine and a facsimile, which always requires a constant light output without being affected by fluctuations in ambient temperature. In addition, since the rare gas discharge lamp does not contain mercury, it is receiving attention from the viewpoint of so-called "global environmental protection".

[0004] The means for increasing the luminous efficiency are to enhance the ultraviolet radiant flux emitted by the rare gas and to efficiently convert visible light from the ultraviolet radiation through a phosphor. Can be roughly divided into points.

[0005] Among them, as a means for efficiently emitting the former ultraviolet radiant flux, it is conventionally known that a lighting method using a square wave is superior to a lighting method using a sine wave. In addition, efforts have been made to optimize the frequency using parameters such as the tube diameter and tube length of the discharge tube, the type and gas pressure of the sealed gas, and the like.

For example, as typified by Japanese Patent Application Laid-Open No. 2-174097, the maximum value is often obtained by changing the pulse width and the duty ratio according to the valve specifications and the characteristics of the sealed gas. However, its luminous efficiency is lower than that of general lighting lamps, leaving room for improvement.

Further, as typified by Japanese Patent Application Laid-Open No. Hei 3-225745, there are many examples in which a pair of parallel band electrodes are provided on the outer surface of a straight tube bulb and a high frequency voltage is applied between the electrodes to light the lamp. Although it is disclosed, it can be used only in limited fields such as a light source for reading information, and cannot be used for general lighting because of its low luminous efficiency.

[0008]

SUMMARY OF THE INVENTION In view of the above, the object of the present invention goes back to the essence of the discharge characteristics of a rare gas discharge lamp and realizes highly efficient ultraviolet light emission. We can find a highly efficient lighting method.

[0009]

In order to solve this problem, a first invention is directed to a transparent conductive film mounted on a bulb of a low pressure discharge lamp, and a lamp bulb application pulse generator for applying a potential to the transparent conductive film. And applying a negative pulse voltage to the transparent conductive film before the rise of the voltage pulse width applied to both ends of the low-pressure discharge lamp and during a period including most of the time width after the rise.

In a second aspect of the present invention, a pulse applied to the transparent conductive film is provided by using a transparent conductive film mounted on a bulb of a low-pressure discharge lamp and a lamp bulb application pulse generator for applying a potential to the transparent conductive film. The discharge lamp is turned on such that the polarity of the pulse is positive and the pulse width is between the time before the fall of the pulse voltage applied to both ends of the low-pressure discharge lamp and the time including most of the time width after the fall. It is characterized by doing.

[0011] In a third aspect of the present invention, a pulse applied to the transparent conductive film is provided by using a transparent conductive film mounted on a bulb of a low pressure discharge lamp and a lamp bulb application pulse generator for applying a potential to the transparent conductive film. Has a temporally positive or negative polarity with respect to one of the electrodes of the lamp, and the negative applied pulse width includes the light emitting time due to pulsed light emission, while the positive applied pulse width includes the light emitting time due to afterglow. And controlling the pulse phase so that the discharge lamp is turned on.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control pulse generator for applying a high voltage pulse potential to a transparent conductive film on the surface of a re-valve, a step-up transformer driven by the control pulse generator and a switching transistor, and a variable nonlinear stable circuit. The present invention has found a lighting control method for optimizing a pulse voltage / current applied to a lamp, an application time interval, and afterglow light emission by a lamp. Hereinafter, embodiments of the present invention will be described.

Taking Xe gas as an example of a rare gas, a simplified excitation / emission operation diagram of this Xe gas is shown in FIG. In FIG. 2, Xe atoms at the time of low-pressure discharge are Xe *, Xe **, or Xe + depending on supplied electric energy.
Is a resonance line from Xe * to the ground level of Xe as main atomic emission when excited by the energy level of
7 nm radiation is observed.

However, if excessive electric energy is supplied in a short time in this excitation process, or if electric energy is supplied continuously, in the former case, ambipolar diffusion from ionized Xe or resonance other than resonance lines will occur. In the transition process, energy loss due to, for example, neutral atom / molecule collision increases, and in the latter case, a loss similar to the former occurs due to an increase in electron density.

By this means, it is possible to supply luminous efficiency in a short time by supplying an appropriate energy level, for example, a level slightly exceeding Xe *, and to supply the next electric energy after a certain pause. It is important in raising.

On the other hand, in a diatomic molecule of Xe 2, as shown in FIG. 2, mainly through the energy level of Xe *,
It constitutes a diatomic molecule and shifts to Xe2 * at a lower level than Xe *, and molecular emission at 172 nm or 158 nm, that is, excimer emission is observed.

In this case as well, electric energy of a level slightly exceeding Xe * is supplied in a short time such that the electron density does not increase, and low electron density which suppresses excitation to the level of Xe2 ** as much as possible. Is important for improving efficiency.

In this way, in order to increase the emission efficiency of the entire ultraviolet radiation while increasing the emission of excimer light, it is necessary to specify the form of electric energy to be supplied, that is, the form of input power, based on the above-mentioned idea.

Specifically, the pulse voltage Vp, the current Ip, and the application time width Tw with respect to a constant input power are specified in accordance with the shape of the arc tube, the type of the sealed gas, and the gas pressure.

Further, the afterglow phenomenon that emits light after the current is cut off greatly changes depending on the type and gas pressure of the sealed rare gas. In the case of Xe, if the energy level of Xe *, that is, the number of metastable atoms, is large, light emission during afterglow is 1%.
47 nm and 172 nm / 158 nm radiation are superimposed more. Of these, 172 nm and 158 nm radiation emits light with a slight delay to 147 nm, so it is important to supply the next electrical energy after this light emission ends.

On the contrary, if the re-application time after the interruption of the voltage pulse is shortened, the afterglow is sharply reduced and the luminous efficiency is reduced. Thus, the optimum repetition frequency f of the pulse is
Assuming that the pulse width is Tw and the afterglow extinction time after the fall of the pulse is Ta, it is expressed by Equation 1.

F = 1 / (Tw + Ta) (1) If f takes a value larger than the value on the right-hand side of Expression 1, the afterglow sharply decreases as described above. If the value on the right side is smaller than the value on the right side, the substantial duty ratio of the applied pulse decreases, and in any case, the luminous efficiency decreases.

Next, based on the above idea, as shown in FIG. 3, a negative lamp bulb pulse voltage Vb1 is applied to the transparent conductive film mounted on the entire tube wall, and then a pulse voltage is applied to both ends of the tube. When a pulse discharge is started by applying a voltage, electrons pass relatively near the center of the cross section of the tube, and an electric energy of a level slightly exceeding an appropriate energy level of Xe, for example, Xe *, with less electric energy. Energy can be supplied in a short time.

At this time, the Xe atom moves to the periphery of the tube due to the negative potential of the tube wall, and in the process, the excitation / emission between the levels such as Xe *, Xe ** and the Xe ground level, that is, the resonance line is generated. Radiate. Ultraviolet radiation radiated from Xe atoms at the tube periphery has less absorption and re-emission processes than ultraviolet radiation radiated from Xe atoms at the tube center, and this leads to an increase in luminous efficiency.

Further, in FIG. 3, when the pulse between the lamp electrodes a is turned off and a positive lamp bulb pulse voltage Vb2 is applied immediately before the after-glow light emission, electrons diffuse to the periphery of the tube to level the electron density. To increase the output of afterglow light emission and shorten the light emission time, that is, to improve the duty ratio of the pulse applied between the lamp electrodes.

On the other hand, Xe *, X
The density of Xe atoms such as e ** increases at the center of the tube, but during afterglow light emission, the transition from Xe *, Xe ** toward the Xe ground level, that is, 147,172 nm emission becomes dominant, and vice versa. The excitation probability of
The ultraviolet radiation absorption coefficient in the tube diameter direction will decrease. On the basis of these results, the afterglow light emission is improved in efficiency.

FIG. 1 is a diagram showing an example of a separately-excited inverter for explaining an embodiment for realizing the above-mentioned lighting conditions. In the figure, 1 is a DC power supply, 2 is a step-up transformer, 3 is a switching transistor, 4 is a control pulse signal generator, 5 is a variable nonlinear ballast composed of a T-shaped circuit of a choke coil and a nonlinear capacitor, and 6 is a surge pulse absorber. 7 is a hot cathode rare gas fluorescent lamp, 8 is a starter for starting, and 9 is a pulse generator for applying a lamp bulb.

The primary side circuit of the step-up transformer 2 represents a pulse voltage generating circuit driven by a pulse signal obtained by the control pulse signal generating device 4, and the primary side circuit is connected via the step-up transformer.
The boost pulse generated on the next circuit side is shaped into a rectangular wave via the variable nonlinear stabilizer 5 and supplied to the lamp.

The variable nonlinear ballast 5 includes a plurality of choke coils L inserted in series with the lamp and a plurality of nonlinear capacitors C inserted in parallel with the lamp.

The pulse waveform is 1 as described above.
A plurality of steps of the step-up transformer 2 are performed so that the pulse voltage Vp and the current Ip necessary to extract the excimer light of 72 nm and 158 nm to the maximum and to maximize the efficiency of ultraviolet radiation including 147 nm radiation are constant. The up terminal and the variable nonlinear stabilizer 5 are adjusted.

The control pulse signal generator 4 is driven at a frequency equal to the repetition frequency represented by the above equation (1).

Further, the pulse time width Tw is controlled by the control pulse signal generator 4 to turn off the switching transistor 3 so as to suppress the electron density in the arc tube to a certain value or less based on the above-described concept. A signal is transmitted and its time width is determined.

In this way, the switching transistor 3 is driven by a pulse capable of ensuring the maximum duty ratio while sufficiently ensuring the occurrence of afterglow.

On the other hand, with respect to the lamp bulb application pulse, the pulse amplified by the lamp bulb application pulse generator 9 based on the signal generated by the control pulse signal generator 4 is applied to the transparent conductive film applied to the inner surface of the lamp bulb. Apply.

The timing of this pulse with respect to the pulse applied between the electrodes is as shown in the time flowcharts of FIGS. That is, a negative pulse is applied to the lamp bulb immediately before the rising of the applied pulse between the lamp electrodes, and a positive pulse is applied immediately before the falling of the applied pulse between the lamp electrodes.

In other words, a high voltage A is applied to the lamp bulb.
The C pulse is applied with the polarity slightly reversed, slightly earlier than the phase of the pulse applied between the lamp electrodes.

The timing for applying these positive and negative pulses is as follows:
As in the emission waveform model shown in FIG. 3C, the pulse emission generated according to the ON / OFF of the pulse applied between the lamp electrodes and the after-glow emission are adjusted to be the maximum.

That is, as a means for maximizing the light emission, the pulse applied to the transparent conductive film has a positive or negative polarity with respect to the discharge plasma of the lamp, and the light emission time of the pulsed light emission is set to a negative applied pulse width. Is controlled, and the pulse phase is controlled such that the positive applied pulse width includes the emission time due to the afterglow.

As another means for maximizing the light emission, the absolute values of the voltages Vb1 and Vb2 of the pulse applied to the lamp bulb can be changed. A powerful control method can be provided in combination.

Further, a lamp bulb application pulse generator 9
The zero-potential point at the time of supplying the lamp to the lamp may be any one electrode of the lamp because the pulse voltage is usually higher than the lighting voltage.

However, this zero potential point may always be fixed to the lower side of the lamp voltage in the circuit as shown in FIG. In a so-called AC lighting circuit in which the polarity alternately changes due to a half-bridge circuit or the like, the zero potential point of the pulse supplied from the lamp bulb application pulse generator 9 to the lamp is inverted according to the timing of the AC lighting circuit. Thereby, it is possible to contribute to improvement of the luminous efficiency. The transparent conductive film may be applied to the outer surface of the bulb, and the surface may be covered with a transparent insulating film.

The zener diode 6 has a function of absorbing a constant high voltage or more and preventing a sudden change in the electron density in the discharge tube in case a high kick voltage is generated at the time of restriking. However, it goes without saying that the Zener diode 6 may be disconnected from the circuit at the time of starting the lamp, depending on the degree of its failure.

[0043]

As described above, according to the present invention, when lighting a low-pressure rare gas discharge lamp, the applied pulse voltage / current, pulse time interval and pulse repetition frequency are optimized, and an AC pulse is applied to the lamp bulb. By controlling ions and electrons in the discharge plasma in the radial direction of the tube, excimer light of 172 nm and 158 nm can be extracted to the maximum.

Further, the efficiency of ultraviolet radiation including 147 nm radiation is maximized, and 147
Visible light can be efficiently converted through a phosphor that can be expected to have a high quantum efficiency in the ultraviolet region longer than nm, and has a great practical value in industrial applications.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a discharge lamp lighting device according to an embodiment of the present invention.

FIG. 2 Principle diagram of rare gas discharge

FIGS. 3 (a) to 3 (c) are diagrams showing lamp applied voltages according to the present invention.
Light output time characteristics

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Step-up transformer 3 Switching transistor 4 Control pulse signal generator 5 Variable nonlinear stabilizer 6 Zener diode 7 Hot cathode type rare gas fluorescent lamp 8 Starting starter 9 Lamp bulb application pulse generator

Claims (4)

[Claims] 1. A rising of a voltage pulse width applied to both ends of the low pressure discharge lamp using a transparent conductive film mounted on a bulb of the low pressure discharge lamp and a lamp bulb application pulse generator for applying a potential to the transparent conductive film. A discharge lamp lighting method in which a negative pulse voltage is applied to the transparent conductive film before and during the time including most of the time width after the rise. 2. The method according to claim 1, wherein the polarity of the pulse applied to the transparent conductive film is positive, using a transparent conductive film mounted on the bulb of the low-pressure discharge lamp and a lamp bulb application pulse generator for applying a potential to the transparent conductive film. A discharge lamp lighting method wherein the pulse width is set so as to be between before the fall of the pulse voltage applied to both ends of the low-pressure discharge lamp and including most of the time width after the fall. 3. A transparent conductive film mounted on a bulb of a low-pressure discharge lamp, and a pulse generator for applying a potential to the transparent conductive film, wherein a pulse applied to the transparent conductive film is applied to one of the lamps. A pulse having a temporally positive or negative polarity with respect to the electrode, so that the negative applied pulse width includes the light emission time due to pulsed light emission, while the positive applied pulse width includes the afterglow light emission time. A discharge lamp lighting method that controls the phase. 4. The method according to claim 3, wherein the positive and negative pulse voltages applied from the lamp bulb application pulse generator to the transparent conductive film are adjusted so as to maximize the sum of pulsed light emission and afterglow light emission. Discharge lamp lighting method.