JP2001160497A - Rare gas fluorescent lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid fluctuation of lamp illuminance in the process from initial stage of lamp lighting up to constant lighting in a rare gas fluorescent lamp lighting device which uses Ac rectangular wave pulses to light the lamp. SOLUTION: In a fluorescent lamp, of which excimer generating gas is sealed into a discharging container made of dielectric with a pair of electrodes on its outer and/or an inner wall and a fluorescent material in its inner wall, and a dielectric barrier discharge is made through above dielectric, and in a rare-gas fluorescent lamp lighting device furnished with lighting device for applying alternate current rectangular wave pulse to the above electrodes, if an effective voltage of the lamp voltage except the apical part is set as Va, and the effective peak-to-peak voltage except the apical part as Vb, voltage ratio Va/Vb is around 80% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp lighting device using a rare gas, and more particularly to a rare gas fluorescent lamp lighting device used for original reading illumination of information devices such as facsimile machines, copiers and scanners. .

[0002]

2. Description of the Related Art In recent years, fluorescent lamps have been used as original reading illumination for information devices such as facsimile machines, copiers and scanners, and as display light sources for large color display devices and the like. In these applications, lamps are required to be smaller, have higher brightness, have a longer life, and have higher reliability. Also,
As a fluorescent lamp, there has been known a fluorescent lamp in which metal electrodes that are electrically connected to the outside are protruded inside both ends of a discharge vessel and use discharge generated between the metal electrodes. Due to restrictions such as low efficiency of ultraviolet intensity obtained from discharge and discharge, lighting devices for fluorescent lamps using dielectric barrier discharge have come to be used. As one form of this dielectric barrier discharge, an external electrode type rare gas fluorescent lamp having a pair of electrodes provided outside the discharge vessel is known. May be disposed inside the discharge vessel. In addition, as a lighting device for an external electrode type rare gas fluorescent lamp, a rectangular wave pulse can provide higher luminance than a sine wave at the same applied voltage, so that a rectangular wave pulse is used as an external electrode type rare gas fluorescent lamp. A lighting device for lighting is used.

Japanese Patent Application Laid-Open No. 6-163006 discloses that in a normal external electrode type rare gas fluorescent lamp, a high voltage must be applied because discharge is performed through a glass bulb.
According to the technique disclosed in this publication, it is disclosed that by using a lighting device that applies an AC rectangular wave pulse to a fluorescent lamp, a high light output can be obtained without increasing the peak value of the applied voltage. ing.

[0004]

The present inventor has tried to turn on a rare gas fluorescent lamp using an AC rectangular wave pulse as disclosed in the above-mentioned publication. At this time, a large transformer impregnated with epoxy resin was used as a transformer in the lighting device 4, and the secondary side inductance was set to 120 mH, the lighting frequency was set to 60 kHz, and the lamp was turned on. As shown in FIG. In the initial stage, after a lapse of more than ten minutes, the lamp illuminance fluctuated by nearly 10%. In general, a light source used for a purpose such as a document reading operation is required to have high light stability. Therefore, a change in lamp illuminance is a fatal problem as a light source in these fields. As a means for preventing a change in the lamp illuminance, it is conceivable to stabilize the lamp illuminance by monitoring the light output, output current, output voltage, and the like, detecting those changes, and performing feedback control. The use of such a means is not preferable because it complicates the circuit device and increases the cost.

[0005] The object of the present invention, in view of the above problems,
In a rare gas fluorescent lamp lighting device that lights a rare gas fluorescent lamp using an AC rectangular wave pulse, rare gas fluorescent lamp lighting that prevents fluctuations in lamp illuminance in the process from the lamp lighting initial stage to a steady lighting state with a simple configuration It is to provide a device.

[0006]

The present invention employs the following means in order to solve the above-mentioned problems.

The first means has a pair of electrodes on an outer wall and / or an inner wall, has a phosphor on an inner wall, and seals an excimer-produced gas in a discharge vessel made of a dielectric. A rare gas fluorescent lamp lighting device comprising: a fluorescent lamp for performing a dielectric barrier discharge; and a lighting device for applying an AC rectangular wave pulse to the electrode, wherein the lighting device includes a lamp voltage of the lamp voltage of the fluorescent lamp. Where the effective rise voltage excluding the pointed voltage portion of Va is Va and the effective peak-to-peak voltage excluding the pointed voltage portion of the lamp voltage is Vb, the voltage ratio Va / Vb becomes approximately 80% or more. It is characterized by having.

[0008] A second means is the first means, wherein the resonance frequency of the resonance circuit formed between the lighting device and the fluorescent lamp is reduced so that the voltage ratio Va / Vb becomes approximately 80% or more. And / or the frequency of the AC square wave pulse output from the lighting device is set high.

A third means has a pair of electrodes on an outer wall and / or an inner wall, has a phosphor on an inner wall, and fills a discharge vessel made of a dielectric with an excimer-produced gas, via the dielectric. A rare gas fluorescent lamp lighting device comprising: a fluorescent lamp for performing a dielectric barrier discharge; and a lighting device for applying an AC rectangular wave pulse to the electrode, wherein the lighting device includes a lamp voltage of the lamp voltage of the fluorescent lamp. When the effective rising voltage excluding the peak voltage portion of the lamp is Va and the effective peak-to-peak voltage excluding the peak voltage portion of the lamp voltage is Vb, the illuminance variation rate from the start of lighting to the steady lighting state is 3 % Or less, and the voltage ratio Va / V
It is characterized by having a characteristic that b is about 72% or more.

A fourth means is the third means, wherein the illuminance variation rate is 3% or less and the voltage ratio Va / V
The resonance frequency of the resonance circuit formed between the lighting device and the fluorescent lamp is set low and / or the frequency of the AC square wave pulse output from the lighting device is increased so that b is approximately 72% or more. It is characterized by having been set.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing an outline of a rare gas fluorescent lamp lighting device according to this embodiment.

In FIG. 1, reference numeral 1 denotes a fluorescent lamp filled with a rare gas, 2 denotes a straight cylindrical glass bulb made of lead glass or the like, which is a dielectric constituting the rare gas fluorescent lamp 1, and 3, 3 '.
Is an external electrode to which an output voltage from the lighting device 4 is applied, which is an electrode provided on the outer wall of the glass bulb 2, and 4 is a lighting device which outputs an AC square wave pulse to be described later for driving the rare gas fluorescent lamp 1. It is.

A phosphor layer (not shown) is formed on almost half of the inner wall of the glass bulb 2.
A rare gas mainly composed of xenon is sealed in the glass bulb 2 at a pressure of several thousand Pa or more.

Several examples of rare gas fluorescent lamps applied to the rare gas fluorescent lamp lighting device of the present invention are shown in FIGS.
It is shown in (c). FIG. 9A is a sectional view of a fluorescent lamp having a pair of electrodes outside the discharge vessel shown in FIG. 1, and FIG.
FIG. 9 is a sectional view of a fluorescent lamp having two electrodes, and FIG.
(C) is a sectional view of a fluorescent lamp having a pair of electrodes inside a discharge vessel. 9B and 9C, the electrodes inside the discharge vessel are covered with a dielectric.

In addition to the examples shown here, a similar effect can be expected by arranging electrodes on the outer surface of the lamp and arranging rod-shaped electrodes at substantially the center of the interior of the lamp.

The operation of the rare gas fluorescent lamp lighting device will be described. The applied voltage output from the lighting device 4 is:
The voltage is applied to the inside of the lamp through the external electrodes 3 and 3 'by capacitive coupling of the discharge gas with the glass bulb 2, which is a dielectric. The discharge form inside the lamp belongs to a form known as an ozonizer discharge or a silent discharge for a long time. This discharge is described in, for example, Reference B. Elias
son and U.S. Kogelschatz "UV
Excimer Radiation Discha
rge "Appl. Phys. B46, 299 (198
The details are described in 8).

FIG. 2 is a diagram showing a detailed configuration of the lighting device 4 shown in FIG.

In FIG. 1, the voltage Vi of the DC voltage source is supplied from the outside. A DC voltage source is loaded with a capacitor 11 and is connected via a choke coil 12 to a switch element 13 using an FET or the like. When the switch element 13 transitions from the on state to the off state, the induced voltage generated in the choke coil 12 is:
The boosted DC voltage Vj is stored in the smoothing capacitor 15 via the diode 14. Incidentally, the chopper circuit including the choke coil 12, the switch element 13, the diode 14, and the smoothing capacitor 15 is called a step-up chopper circuit.

Switch elements 16 and 1 using FETs and the like
7. The inverter circuit composed of the step-up transformer 18 is configured by a push-pull system, and the output voltage Vj of the chopper circuit is connected to the center tap on the primary side of the step-up transformer 18. Here, the step-up transformer 18 has a steep change rate of the voltage applied to the lamp from the time immediately before the start of discharge to the time when the peak voltage value is reached after the start of discharge, such that the efficiency of excimer generation does not decrease. Is used.

The pulse width modulated control signal generated in the PWM control circuit 19 is input to an inverter gate signal generation circuit comprising transistors 20, 21 and resistors 22, 23, etc., whereby the gate signal G for the inverter circuit is generated.
U and GL are generated. Gate signal G for inverter circuit
U and GL are input to the gate terminals of the switch elements 16 and 17 for the inverter circuit via the resistors 24 and 25, respectively.

On the other hand, the chopper gate signal generating circuit is constituted by using a signal adder composed of diodes 26 and 27 and a resistor 28, and the choppers are input to the gate signals GU and GL for the inverter circuit. A circuit gate signal Gc is generated. The chopper circuit gate signal Gc is input to the gate terminal of the chopper circuit switch element 13 via a buffer circuit including transistors 29 and 30, a differentiating circuit including a capacitor 31 and a resistor 32, and a resistor 33.

Next, the principle of preventing illuminance fluctuation in the rare gas fluorescent lamp lighting device according to this embodiment will be described with reference to FIGS.

FIG. 3 is a diagram showing an equivalent circuit formed between the rare gas fluorescent lamp 1 and the lighting device 4 of the rare gas fluorescent lamp lighting device according to the present embodiment.

In FIG. 1, a rare gas fluorescent lamp 1 has a discharge resistance Rg formed in a discharge path of a discharge plasma space,
It is represented by a circuit element consisting of a discharge switch SWg, a condensed component Cg formed in a discharge plasma space, and a capacitor component Cd formed between glass bulbs as a dielectric between glass bulb electrodes. 18 and a rectangular wave pulse power supply E, and the space between the rare gas fluorescent lamp 1 and the lighting device 4 can be represented by a stray capacitance Ce such as a wiring or a transformer.

FIG. 4A is a diagram showing a lamp voltage waveform applied to the rare gas fluorescent lamp 1 in the equivalent circuit shown in FIG. 3, and FIG. 4B is a diagram showing the equivalent circuit shown in FIG. A lamp voltage waveform when the resonance frequency f of the formed resonance circuit is relatively high, and FIG. 4C shows a lamp when the resonance frequency f of the resonance circuit formed in the equivalent circuit shown in FIG. 3 is relatively low. It is a figure showing a voltage waveform.

As shown in FIG. 4A, of the lamp voltage waveforms, a voltage waveform indicated by A (hereinafter referred to as a resonance voltage portion) substantially corresponds to the rare gas fluorescent lamp in the equivalent circuit shown in FIG. It is considered that it is determined by the resonance frequency f of the resonance circuit formed between the lighting device 1 and the lighting device 4.

Here, the resonance frequency f = 1 / 2π√ (L
C) L is the secondary side inductance of the transformer 18 and C is the capacitance formed by the capacitances Cd and Cg of the rare gas fluorescent lamp 1, the floating capacitance Ce and the like.

In the lamp voltage, a voltage waveform indicated by B (hereinafter referred to as a rising voltage portion or a falling voltage portion) corresponds to an AC rectangular wave pulse applied from the lighting device 4 to the rare gas fluorescent lamp 1. It appears at the time of switching between positive and negative, and the larger the rising voltage portion B or falling voltage portion B, the greater the light emission amount of the lamp.

In the rare gas fluorescent lamp lighting device as shown in FIG. 2, the transformer 18 provided in the lighting device 4 generates heat due to iron loss, copper loss and the like when the lamp is turned on. As the transformer temperature rises and the permeability of the transformer core increases with the temperature rise,
The inductance L also increases.

Therefore, in the steady lighting state, as compared with the initial lighting of the rare gas fluorescent lamp 1, the resonance frequency f decreases as the inductance L increases, as is apparent from the above equation.
For example, from the lamp voltage waveform shown in FIG.
The operation shifts to the ramp voltage waveform shown in FIG.

FIG. 4C shows the ramp voltage waveform.
Compared with the lamp voltage waveform of (b), the resonance voltage portion A is horizontal, and the rising voltage portion B and the falling voltage portion B are large, so that the amount of lamp light emission is increased. Thus, it can be seen that the illuminance of the lamp varies with the variation of the resonance frequency f.

In the invention of the present embodiment, based on the above findings, in order to prevent the illuminance fluctuation due to the fluctuation of the resonance frequency f, the resonance voltage portion A is set to a horizontal state regardless of the fluctuation of the resonance frequency f from the start of lighting. Close the resonance voltage part A
Is intended to suppress the fluctuation of.

For this purpose, as shown in FIG.
The voltage Va is a rising (or falling) voltage excluding the peak voltage portion of the lamp voltage (hereinafter, referred to as an effective rising voltage), and the voltage Vb is a peak-to-peak voltage excluding the peak voltage portion of the lamp voltage. to peak)
When a voltage (hereinafter referred to as an effective peak-to-peak voltage) is used, the voltage ratio Va / Vb may be increased from the start of lighting of the lamp.

FIG. 5 shows a voltage ratio V for each of various transformers 18 used in a rare gas fluorescent lamp lighting device having a lighting device for applying an AC rectangular wave pulse to the rare gas fluorescent lamp.
5 is a graph showing the illuminance change rate at the start of lighting in a steady lighting state in a / Vb. Here, the illuminance variation rate is represented by the following equation.

Illuminance fluctuation rate = ｛(Illuminance at steady stable lighting−
Illuminance at start of lighting) / Illuminance at steady steady lighting｝ × 100
(%) In the figure, the horizontal axis represents the voltage ratio Va / Vb (%), and the vertical axis represents the illuminance variation rate (%), and a represents the case where a large transformer impregnated with epoxy resin is used as the transformer 18. Indicates the illuminance variation rate at each voltage ratio Va / Vb, and b indicates the illuminance variation rate at each voltage ratio Va / Vb when a large transformer not impregnated with epoxy resin is used as the transformer 18. Yes, c is transformer 1
8 shows the illuminance variation rate at each voltage ratio Va / Vb when a small transformer not impregnated with epoxy resin is used.

It is considered that a large transformer impregnated with an epoxy resin has a lower heat release than the large transformer not impregnated with the epoxy resin or a small transformer not impregnated with the epoxy resin, and the temperature of the transformer is easily increased. Can be

As is clear from the graph shown in FIG. 5, the voltage ratio Va / Vb is approximately 80% in each of the transformers.
With this setting, the illuminance variation rate of 3% or less, which does not hinder the light source for document reading, can be suppressed. Further, in the case of a certain transformer (for example, a large transformer b or a small transformer c), when the voltage ratio Va / Vb is set to approximately 72% or more, the illuminance variation rate is already 3% or less.
Further, the illuminance variation rate can be reduced.

FIG. 6 shows a transformer 18 using a large transformer impregnated with epoxy resin in order to set the voltage ratio Va / Vb to 80% or more as compared with the one having a large illuminance variation rate shown in FIG. Secondary inductance L of 240m
It is a figure which shows the change of the lamp illuminance from the start of lighting of a lamp to a steady lighting state when it is twice as large as H.

As is apparent from a comparison between FIG. 6 and FIG. 7, the illuminance variation is 10% or more at first, but according to the present embodiment, the illuminance variation can be reduced to 3% or less. .

FIG. 8 is a diagram for explaining another means for increasing the voltage ratio Va / Vb.

FIG. 8A shows a lamp voltage waveform when the frequency of the AC rectangular wave pulse is relatively low (frequency f1) in the rare gas fluorescent lamp lighting device shown in FIG.
(B) shows a comparative example in which the frequency of the AC rectangular wave pulse is relatively high (frequency f) in the rare gas fluorescent lamp lighting device shown in FIG.
It is a figure which shows the lamp voltage waveform in the case of 2).

In the figure, A is a rare gas fluorescent lamp 1
The voltage Va1 and Va2 determined by the resonance frequency f of the resonance circuit formed between the lighting device 4 and the lighting device 4 are effective rising voltages as described with reference to FIG. 4A, and the voltages Vb1 and Vb2 are also Similarly, as described with reference to FIG. 4A, the effective peak-to-peak voltage is used.

As shown in these figures, as compared with the frequency f1 of the AC rectangular wave pulse shown in FIG.
As the frequency f2 of the AC rectangular wave pulse increases as shown in FIG. 7, the positive and negative periods of the AC rectangular pulse are switched before the resonance voltage portion A decreases so much, so that the voltage ratio (Va
2 / Vb2)> voltage ratio (Va1 / Vb1), and the voltage ratio Va / Vb, as described with reference to FIG.
Can be increased, and the illuminance variation rate can be reduced.

In the above embodiment, the voltage ratio Va /
A case where the resonance frequency of a resonance circuit formed between the lighting device 4 and the fluorescent lamp 1 is set low in order to increase Vb;
Although the case where the frequency of the AC rectangular wave pulse output from the lighting device 4 is set to be high has been described, both may be used together as necessary.

[0046]

According to the first aspect of the present invention, by using a lighting device having a voltage ratio Va / Vb of about 80% or more, the lamp in the process from the initial stage of the lamp operation to the steady operation state is used. Fluctuations in illuminance can be suppressed without adding special circuit means, and is extremely effective as a light source such as a document reading light source.

According to the second aspect of the present invention, the resonance frequency of the resonance circuit formed between the lighting device and the fluorescent lamp can be set low, or the AC rectangular wave pulse output from the lighting device can be reduced. The voltage ratio Va / Vb can be set to be approximately 80% or more by a simple means such as setting a high frequency.

According to the third aspect of the present invention, the illuminance variation rate at the start of lighting is 3 with respect to the steady lighting state.
% Or less and a voltage ratio Va / Vb of about 72% or more is used, so that extra circuit means is added to the variation in lamp illuminance in the process from the initial lighting of the lamp to the steady lighting state. It can be easily reduced without the need.

According to the fourth aspect of the present invention, the resonance frequency of the resonance circuit formed between the lighting device and the fluorescent lamp can be set low, or the AC rectangular wave pulse output from the lighting device can be reduced. By simple means such as setting a high frequency, it is possible to easily set the illuminance variation rate to be 3% or less and the voltage ratio Va / Vb to be about 72% or more.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a rare gas fluorescent lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a detailed configuration of a lighting device 4 illustrated in FIG. 1;

FIG. 3 is a diagram showing an equivalent circuit formed between the rare gas fluorescent lamp 1 and the lighting device 4 of the rare gas fluorescent lamp lighting device according to the present embodiment.

4 is a diagram showing a lamp voltage waveform applied to the rare gas fluorescent lamp 1 in the equivalent circuit shown in FIG.

FIG. 5 is a graph showing an illuminance variation rate at the start of lighting in a steady lighting state at each voltage ratio Va / Vb for various transformers used in the rare gas fluorescent lamp lighting device.

FIG. 6 is a diagram showing a change in lamp illuminance from the start of lighting of the rare gas fluorescent lamp lighting device according to the present embodiment to the steady lighting state.

FIG. 7 is a diagram illustrating an example of a large change in lamp illuminance from the start of lighting of the rare gas fluorescent lamp lighting device to the steady lighting state.

FIG. 8 is a diagram for explaining another means for increasing the voltage ratio (Va / Vb).

FIG. 9 is a diagram showing several examples of a cross section of a rare gas fluorescent lamp applied to the rare gas fluorescent lamp lighting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluorescent lamp 2 Glass bulb 3, 3 'External electrode 4 Lighting device 11 Capacitor 12 Choke coil 13 Switch element for chopper circuit 14 Diode 15 Smoothing capacitor 16, 17 Switch element for inverter circuit 18 Boost transformer 19 PWM control circuit

Claims (4)

[Claims] An excimer-producing gas is sealed in a discharge vessel comprising a pair of electrodes on an outer wall and / or an inner wall, a phosphor on an inner wall, a dielectric, and a dielectric via the dielectric. In a rare gas fluorescent lamp lighting device including a fluorescent lamp to be subjected to barrier discharge and a lighting device that applies an AC rectangular wave pulse to the electrode, the lighting device includes a lamp voltage of the fluorescent lamp.
The effective rise voltage excluding the peak voltage portion of the lamp voltage is V
a, a rare gas fluorescent lamp having a characteristic such that a voltage ratio Va / Vb becomes approximately 80% or more when an effective peak-to-peak voltage excluding a pointed voltage portion of a lamp voltage is Vb. Lighting device. 2. The method according to claim 1, wherein a resonance frequency of a resonance circuit formed between the lighting device and the fluorescent lamp is set to be low so that the voltage ratio Va / Vb is approximately 80% or more, and / or A rare gas fluorescent lamp lighting device, wherein the frequency of the AC rectangular wave pulse output from the lighting device is set high. 3. A discharge vessel comprising a pair of electrodes on an outer wall and / or an inner wall, a fluorescent substance on an inner wall, and a dielectric discharge vessel is filled with an excimer-produced gas. In a rare gas fluorescent lamp lighting device including a fluorescent lamp to be subjected to barrier discharge and a lighting device that applies an AC rectangular wave pulse to the electrode, the lighting device includes a lamp voltage of the fluorescent lamp.
The effective rise voltage excluding the peak voltage portion of the lamp voltage is V
a, when the effective peak-to-peak voltage excluding the peak voltage portion of the lamp voltage is Vb, the illuminance variation rate from the start of lighting to the steady lighting state is 3% or less, and the voltage ratio Va / Vb A rare gas fluorescent lamp lighting device characterized by having a characteristic that is approximately 72% or more. 4. The method according to claim 3, wherein the illuminance change rate is 3% or less and the voltage ratio Va is less than 3%.
The resonance frequency of a resonance circuit formed between the lighting device and the fluorescent lamp is set low so that / Vb is approximately 72% or more, and / or the frequency of the AC square wave pulse output from the lighting device is reduced. A rare gas fluorescent lamp lighting device characterized by being set high.