JPH1197194A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a high efficiency ultraviolet ray range illumination by optimizing a pulse voltage and current applied to a lamp, application time interval and aftergrow illumination by means of a step-up transformer driven by a control pulse generator and a switching transistor and a variable nonlinear stabilizer. SOLUTION: A plurality of step-up terminals of a step-up transformer 2 and a variable nonlinear stabilizer 5 are controlled so that a pulse voltage Vp and a current Ip required to take out the maximum level of excimer beam of 172 nm, 158 nm and to enhance a ultraviolet radiation efficiency including the radiation of 147 nm can be made constant, in relation to the waveform of pulse. While generation of aftergrow is thus assured sufficiently, with the pulse for securing the maximum duty ratio, a switching transistor is driven. Accordingly, the maximum efficienty of ultraviolet radiation is attained including the radiation of excimer beam of 172 nm, 158 nm and the radiation of 147 nm.

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 for lighting a low pressure discharge lamp.

[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 such as a copier or a facsimile for reading information, which always requires a constant light output without being affected by fluctuations in the 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".

[0003] The means for increasing the luminous efficiency are how to enhance the ultraviolet radiant flux emitted by the rare gas, and how to efficiently convert visible light from the ultraviolet radiation via a phosphor. Can be roughly divided into points.

Among these, as the former means for efficiently emitting ultraviolet radiation, it is conventionally known that a lighting method using a rectangular wave is superior to a lighting method using a sine wave. Also, efforts have been made to optimize the frequency by using the tube diameter and tube length of the discharge tube, the type and gas pressure of the sealed gas as parameters, and the like. However, an efficient lighting control method according to the intrinsic characteristics of the rare gas discharge has not been realized.

[0005]

The problem to be solved by the present invention goes back to the essence of the discharge characteristics of rare gas discharge lamps, and how to find a practical control method for realizing highly efficient ultraviolet light emission. is there.

[0006]

According to the present invention, a pulse voltage / current applied to a lamp and a voltage applied to a lamp are controlled by a step-up transformer and a variable nonlinear ballast driven by a control pulse generator and a switching transistor. A lighting control system that optimizes the time interval and afterglow emission is found.

Further, a lighting control system which maximizes the luminous efficiency of excimer light by adding information of an excimer light measuring sensor to the lighting control system is found.

Furthermore, a lamp emission measuring sensor is added to the lighting control system and the excimer light measuring sensor to find a lighting control system that maximizes the effective ultraviolet radiation of the phosphor.

[0009]

Embodiments of the present invention will be described below.

(Embodiment 1) Taking Xe gas as an example of a rare gas, a simplified excitation / emission operation of this Xe gas is shown in FIG.

In FIG. 2, Xe atoms at the time of low-pressure discharge are excited to the energy level of Xe *, Xe **, or Xe + according to the supplied electric energy, and Xe * to Xe 147 nm which is the resonance line
Radiation is observed.

However, if excessive electric energy is supplied in a short time or electric energy is continuously supplied in the excitation process, in the former case, bipolar diffusion from ionized Xe or non-resonant lines may 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 an appropriate energy level, for example, electric energy of a level slightly exceeding Xe * in a short time, and to supply the next electric energy after a certain pause, thereby improving the luminous efficiency. It is important in raising.

On the other hand, in the 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 Xe ₂ * at a lower level than Xe *, and molecular emission at 172 nm or 158 nm, ie, excimer emission is observed. In this case as well, electric energy of a level slightly exceeding Xe * is supplied in a short time so that the electron density does not increase, and a low electron density that suppresses excitation to the Xe ₂ ** level as much as possible is maintained. Is important for improving efficiency.

In this way, in order to increase the luminous efficiency of the entire ultraviolet radiation while increasing the emission of excimer light, it is necessary to specify the electric energy to be supplied, that is, the form of the input power, based on the above-described concept. Specifically, the pulse voltage Vp and the current I for a constant input power
The purpose is to specify p and the application time width Tw according to the specifications of the shape of the arc tube and the type and gas pressure of the sealed gas.

Also, the afterglow phenomenon that emits light after the current is cut off greatly changes depending on the type of rare gas and the gas pressure. In the case of Xe, if there are many (energy level) metastable atoms of Xe *, the emission at the time of afterglow is 147 nm.
And 172 nm and 158 nm radiation are superimposed more. Of these, 172 nm and 158 nm radiation is 147 n
Since light is emitted with a slight delay from m, it is important to supply the next electric energy after the light emission ends.

On the other hand, if the re-application time after the interruption of the voltage pulse is shortened, the afterglow sharply decreases and the luminous efficiency decreases. Thereby, the optimum repetition frequency f of the pulse
Is expressed by equation (1), where Ta is the afterglow extinction time after pulse application.

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

FIG. 1 is a diagram illustrating an example of a separately-excited inverter for explaining a first embodiment for realizing the above-mentioned lighting conditions.

In FIG. 1, 1 is a DC power supply, 2 is a step-up transformer, 3 is a switching transistor, 4 is a control pulse generator, 5 is a variable nonlinear stabilizer comprising a T-shaped circuit of a choke coil and a nonlinear capacitor, 6 is A Zener diode (or ZNR may be used) for absorbing a surge pulse, 7 is a hot cathode type rare gas fluorescent lamp (hereinafter referred to as a lamp), and 8 is a starter for starting.

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 generator 4, and a step-up pulse generated on the secondary circuit side through the step-up transformer 2 is a variable non-linear circuit. The light is shaped into a rectangular wave via the ballast 5 and supplied to the lamp 7. The variable nonlinear ballast 5 includes a plurality of choke coils L inserted in series with the lamp 7 and a plurality of nonlinear capacitors C inserted in parallel with the lamp 7.

Further, 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 generator 4 is driven at a frequency equal to the repetition frequency represented by the above equation (1). Further, with respect to the pulse time width Tw, a control signal for turning off the control transistor is transmitted from the control pulse generator 4 to 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. , Determine the time span.

In this manner, the switching transistor 3 is driven by a pulse capable of ensuring the maximum duty ratio while sufficiently ensuring the occurrence of afterglow. Thereby, the excimer light of 172 nm and 158 nm is maximized. In addition, the efficiency of ultraviolet radiation including 147 nm radiation is also maximized, so that visible light can be efficiently converted from ultraviolet radiation through a phosphor that can be expected to have high quantum efficiency in a long wavelength region. is there.

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.

In FIG. 1, 7 is described as a hot cathode fluorescent lamp, but it is obvious that an electric field discharge fluorescent lamp having external parallel electrodes may be used instead.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. Here, the bulb of the lamp 7 shown in FIG. 1 is made of a glass material capable of transmitting the vacuum ultraviolet region, and the lamp 7 is a rare gas discharge lamp in which all or a part of the tube excludes a phosphor. Hereinafter, the points different from FIG. 1 will be mainly described.

The half value width of the excimer light measuring sensor 9 is 10n.
It is manufactured to have a maximum spectral responsivity around 172 nm at about m, and the lamp radiation measurement sensor 10 has a substantially constant spectral responsivity in the range of 130 nm to 180 nm.

The control pulse generator 14 calculates the optimal lighting frequency of excimer light emission based on the intensity of excimer light detected from the information of the excimer light measuring sensor 9 and the extinction time of the afterglow, and calculates this as the switching transistor. Input to 3 to drive the lamp 7.

That is, since the excimer light measuring sensor 9 can measure not only the magnitude of the excimer light but also the duration of the afterglow immediately after the pulse is turned off, the constant value is set in the description of the above equation (1). The minute fluctuation of the afterglow extinction time Ta caused by a change other than the lighting condition can be corrected, and the pulse repetition frequency f is further optimized.

In another system, signals from both the excimer light measuring sensor 9 and the lamp radiation measuring sensor 10 are sent to the control pulse generator 14. The control pulse generator 14 analyzes these two signals and changes the three parameters of the pulse width and repetition frequency, and the ramp applied pulse voltage variable signal to be sent to the step-up transformer 2 and sends them to the switching transistor 3. And maximizing excimer radiation and maximizing effective ultraviolet radiation.

Further, by providing a set frequency input terminal 11 as shown in FIG. 4 to the above-described feedback circuit function, even if a command to change the set frequency is received from outside the lighting device, the control pulse generator 14 By extending the calculation function of the above, the optimum lighting conditions can be manually or automatically determined in the feedback circuit.

The expansion of the arithmetic function can be easily realized by adding an arithmetic function of a CPU, that is, a microcomputer, in addition to the function of the control IC for the switching regulator which the control pulse generator 14 originally had. FIG. 3 shows an example of a schematic flowchart for explaining the operation of the CPU.

In FIG. 3, after lighting at a constant power, the pulse time width Tw and the repetition frequency f are calculated and controlled while changing the pulse voltage and current, and the effective ultraviolet radiation is measured. Here, the effective ultraviolet radiation will be described. When converting ultraviolet radiation into visible radiation with a phosphor, the excimer light radiation measurement sensor 9
If the irradiance at 172 nm and the total irradiance at 172 nm obtained from FIGS. 10 and 10 are a and b, respectively, ka + (ba), that is, (k−1) a + b represents the effective ultraviolet irradiance of this phosphor.

Here, k represents an increment of the excitation wavelength sensitivity at 172 nm of the phosphor, and is assumed to be a value larger than 1. The maximum effective irradiance and its lighting control conditions are determined by selecting a local maximum value from this data group, further shifting the repetition frequency f, and experimentally confirming the afterglow extinction time Ta.

Although the schematic flow in FIG. 3 shows a start from a constant power, it goes without saying that a method of controlling the lighting system through the above flow while automatically or manually changing the power can be used. .

(Embodiment 3) Next, a third embodiment of the present invention will be described below. When the lighting device with the feedback circuit function according to the second embodiment is incorporated as a light source device for reading information such as a copying machine or a facsimile, the lamp 7 may be a hot cathode rare gas fluorescent lamp or a The excimer light measuring sensor 9 and the lamp radiation measuring sensor 10 as electric field discharge fluorescent lamps having external parallel electrodes can be substituted for the photoelectric output of the information reading sensor as a visible range photometric sensor.

Further, a function of receiving a switching command of the lighting frequency required from the entire system from the set frequency input terminal 11 and realizing a function capable of immediately responding to the setting of the optimum lighting condition can be realized.

[0039]

As described above, according to the present invention, when operating a low-pressure rare gas discharge lamp, the excimer of 172 nm and 158 nm is optimized by optimizing the applied pulse voltage / current, pulse time interval and pulse repetition frequency. Light can be extracted to the maximum.

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 configuration diagram illustrating a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 Principle diagram of rare gas discharge

FIG. 3 is a schematic flowchart of lighting control according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating a discharge lamp lighting device according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DC power supply 2 Step-up transformer 3 Switching transistor 4 Control pulse generator 5 Variable nonlinear ballast 6 Zener diode 7 Rare gas fluorescent lamp 8 Starter 9 Excimer light measurement sensor 10 Lamp radiation measurement sensor 14 Control pulse generator

Claims (3)

[Claims] 1. A low-pressure rare gas discharge lamp is controlled to be turned on with a pulse voltage and a current for maximizing ultraviolet radiation including excimer light and a lighting time width, and a repetition frequency is a sum of the lighting time width and the after-glow extinction time. A discharge lamp lighting device including a lighting circuit driven at a frequency represented by a reciprocal. 2. An excimer light measuring sensor, and a control pulse generator for generating an optimum repetition frequency of the excimer light based on the intensity of the excimer light detected from information of the sensor, the afterglow extinction time and the lighting time width. A discharge lamp lighting device comprising: 3. An excimer light measuring sensor, a lamp radiation measuring sensor, and a phosphor effective ultraviolet radiation are calculated based on the above two types of sensor information to obtain an optimum repetition frequency, lighting time interval, pulse voltage and current. And a control pulse generator for generating a discharge pulse.