JPH11283777A - Discharge lamp lighting device, discharge lamp device and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To light a discharge lamp by applying a high-frequency A.C. voltage of which the waveform is regulated, enhance its luminous efficiency and reduce noise by installing a high-frequency generating means to apply a high-frequency A.C. voltage of which the waveform is so regulated as to flow a lamp current having a sufficient pause period between a pair of electrodes. SOLUTION: A high-frequency generating means 22 is installed between a pair of electrodes. The high-frequency generating means 22 includes a switching circuit 22b 1, generates a high-frequency A.C. voltage in response to the switching of the switching circuit 22b 1 and is equipped with a control means capable of controlling the ON-period and the OFF-period of the switching circuit 22b 1. A circuit structure to impart a sufficient pause period to a lamp current is thereby provided by regulating the ON-period and the OFF-period of the switching circuit 22b 1. That is, when the ON-period and the OFF-period of the switching circuit 22b 1 is appropriately regulated, the output wave form is set asymmetrical between its positive and negative sides by superimposing a D.C. component on the high-frequency alternating current, so that a sufficient pause period can be imparted to the lamp current.

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 discharge lamp in which a discharge medium mainly composed of a rare gas is sealed, a discharge lamp device and an apparatus using the same.

[0002]

2. Description of the Related Art Rare gas discharge lamps emit phosphors mainly by ultraviolet rays generated by rare gas discharge.
Since the luminous intensity does not depend on the temperature, the luminous flux rising characteristic at a low temperature is good, but there is a problem that the luminous efficiency is lower than that of a discharge lamp using mercury vapor discharge.

On the other hand, Japanese Patent Application Laid-Open No. 58-135563
Gazette, Japanese Unexamined Patent Publication No. Hei.
JP-A-2794 and JP-A-9-199285 disclose that the luminous efficiency is improved by pulsing a discharge lamp that emits visible light by exciting a phosphor layer with ultraviolet light generated by rare gas discharge. Is described.

FIG. 11 is a circuit diagram showing a discharge lamp lighting device disclosed in Japanese Patent Application Laid-Open No. 9-199285.

[0005] In the figure, 1 is an external electrode type fluorescent discharge lamp (discharge lamp), 6 is a DC power supply, 7 is a drive circuit, 8 switching elements, and 9 is a transformer.

[0006] The switching element 8 is turned on / off by a drive signal of a predetermined frequency output from the drive circuit 7. When the switching element 8 is turned on by the drive signal, a current flows through the path of the DC power supply 6 → the primary winding of the transformer 9 → the switching element 8 → the ground G, and energy is stored in the transformer 9. When the switching element 8 is turned off, the current flowing in the transformer is cut off, so that the energy stored in the transformer 9 is released, and the primary side and the secondary side of the transformer 9 are shown in FIG. A voltage waveform having a sharp rise, that is, a pulse voltage, is repeatedly generated and applied to the discharge lamp.

Thus, the voltage of the waveform having the only maximum peak within one cycle of the repetitive waveform of the ramp voltage becomes zero.
Is 2W with respect to the repetition period t of the voltage waveform.
o <t.

According to this conventional discharge lamp lighting device,
Since the luminous efficiency is improved about two to three times as compared with the case where a sine wave AC voltage is applied to the discharge lamp to light it, high illuminance can be obtained.

[0009]

However, when the lamp is lit by applying a pulse voltage to the discharge lamp as described above, the peak value of the pulse voltage becomes extremely high, so that the lamp is lit by applying a sine wave AC voltage. There is a problem that the noise becomes extremely large as compared with the case, which is a hindrance factor for practical use.

According to the study of the present inventor, in the case of rare gas discharge, if a lamp current is turned on with a pause period, an afterglow is generated to improve luminous efficiency.
It has been found that application of a pulse voltage is not an essential condition.
From this, the present inventor has discovered that even when an AC voltage is applied instead of a pulse voltage, the luminous efficiency can be improved if a pause period is generated in the lamp current.

The present invention has been made on the basis of the above findings, and uses a discharge lamp lighting device which emits light by applying a high-frequency AC voltage having a regulated waveform, has high luminous efficiency, and has little noise. An object is to provide a discharge lamp device and equipment.

[0012]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device, wherein an airtight discharge vessel in which a discharge medium mainly composed of a rare gas is sealed, and at least one of which is disposed on an outer surface of the discharge vessel. And a high-frequency generating means for applying a high-frequency AC voltage having a waveform adjusted by superimposing a DC voltage so that a lamp current having a pause period flows between the pair of electrodes of the discharge lamp having the pair of electrodes. It is characterized by having.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

The phrase "mainly composed of a rare gas" with respect to a discharge lamp means that it is allowed to contain mercury and the like in an auxiliary manner. It suffices if the main component of the discharge is a rare gas. Xenon is preferred as the rare gas, but if necessary, any one of krypton, argon, neon, and helium or a mixture of any two or more of them can be used.

The ultraviolet rays generated by the rare gas discharge may be directly led out of the hermetic container and used. However, the phosphor layer disposed on the inner surface side of the lamp is irradiated to convert it into visible light, Light can be used for illumination.

The material of the airtight container may be any material as long as it has airtightness and heat resistance to the operating temperature, but soft glass, hard glass or semi-hard glass is usually used. In the case where ultraviolet light is taken out of the discharge lamp and used for illumination, an airtight container that transmits ultraviolet light, such as quartz glass, is used.

Further, the shape of the airtight container is not limited.
Therefore, it can be formed in a tubular or flat shape. It may be a tube, a straight tube or a curved tube. Further, the curved tube may be annular, semi-circular, U-shaped, W-shaped, saddle-shaped or spiral-shaped.

Furthermore, the thickness and length of the tube are also arbitrary, and a size suitable for the application may be selected.

"At least one of the pair of electrodes disposed on the outer surface of the discharge vessel" means that both the pair of electrodes are disposed on the outer surface of the discharge vessel and that one of the electrodes is disposed on the outer surface of the discharge vessel. This is a meaning including an aspect in which the other electrode is provided inside the discharge vessel. If at least one of the pair of electrodes is disposed on the outer surface of the discharge vessel, a dielectric barrier discharge is generated because a capacitance having the wall of the discharge vessel as a dielectric is interposed between the electrodes. This is because the gas can be discharged to emit ultraviolet rays.

Further, one electrode is placed in the discharge vessel,
It extends along the other electrode (hereinafter, referred to as “external electrode”) disposed on the outer surface (hereinafter, referred to as “internal electrode”).
That. Accordingly, the discharge starting voltage and the discharge sustaining voltage of the discharge lamp can be reduced as compared with the case where the pair of electrodes is disposed on the outer surface of the discharge vessel.

Further, by grounding the electrode provided on the outer surface, radiation noise can be further reduced.

Furthermore, by energizing and heating the internal electrodes, thermions can be emitted to increase the lamp current and increase the amount of light.

When a phosphor layer is formed on the inner surface side of the discharge vessel, the type of the phosphor can be freely selected from known phosphors, and for example, a three-wavelength phosphor can be used. . In addition, "the inner surface side of the discharge vessel" means not only that the phosphor layer is directly formed on the inner surface of the discharge vessel,
This means that a phosphor layer can be indirectly formed, for example, by forming a protective film on the inner surface of the discharge vessel and then forming a phosphor layer thereon.

High frequency means means 1K
Hz or higher, preferably 4 to 200 KHz
Say.

The "AC voltage" refers to a mode in which positive and negative waveforms are applied alternately and continuously without a pause, and may be a positive-negative asymmetrical AC or a positive-negative asymmetrical AC.

The present invention is characterized in that the waveform of the high-frequency AC voltage is adjusted so that a lamp current having a sufficient rest period flows. Note that the “sufficient rest period” may be any value as long as afterglow occurs in the discharge lamp during the rest period of the lamp current.

The method of adjusting the waveform of the high-frequency AC voltage as described above does not matter, and therefore does not matter. For example, harmonics can be superimposed on the fundamental wave of a sine wave to make the rising and falling portions of the voltage waveform relatively steep, or a DC voltage can be superimposed to make a positive / negative asymmetric waveform. .

As a means for generating a high frequency, an inverter is generally used, but the invention is not limited to this.

In the present invention, since the discharge lamp is lit by applying a high-frequency AC voltage to the discharge lamp, there is not much radiation noise as in the conventional pulse lighting.

In addition, since the voltage waveform applied to the discharge lamp is adjusted, a sufficient rest period can be provided for the lamp current, so that an afterglow is generated, and the luminous efficiency is improved by the effect to obtain high illuminance. Can be.

As a result, the luminous efficiency obtained is somewhat lower than in the case of pulse lighting, but is a sufficiently high value as compared with sine wave lighting.

Further, since the voltage waveform can be easily adjusted, the circuit configuration can be relatively simplified.

Further, in the present invention, since the harmonic components are smaller than in the case of the pulse voltage, the radiation noise is small.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device,
2. The discharge lamp lighting device according to claim 1, wherein the high-frequency generating means outputs a high-frequency AC voltage having a waveform higher than that of the fundamental wave by superimposing the higher harmonics and having sharply rising and falling portions.

If the harmonic is an odd-order harmonic, the rising and falling portions of the voltage waveform can be sharpened. In practice, a sufficiently effective waveform can be obtained by superimposing the third harmonic with a phase having a lower peak value than that of the fundamental wave.

As a circuit configuration for superimposing harmonics, for example, high-frequency generation means for generating a fundamental wave may be used.
A configuration is adopted in which a resonance circuit that resonates with a harmonic is coupled, or a high-frequency generating unit that generates a fundamental wave and a high-frequency generating unit that generates a harmonic are used to superimpose their outputs and apply the resultant to a discharge lamp. be able to.

Thus, it has been found that if the waveform of the voltage applied to the discharge lamp is steep at the rising and falling portions, a sufficient rest period for the lamp current occurs.

Then, afterglow can be generated during the idle period.

According to a third aspect of the present invention, there is provided the discharge lamp lighting device according to the first or second aspect, wherein the high frequency generating means includes a switching means, and a first means resonating with a fundamental wave.
, An output transformer, and a second resonance circuit that is magnetically coupled to the output transformer and resonates at higher harmonics.

The present invention defines a circuit configuration for steepening the rising and falling portions of the voltage waveform to provide a sufficient rest period for the lamp current.

Since the waveform of the output voltage can be symmetrical,
It is preferable to use a high frequency generator having good waveform symmetry, for example, a parallel inverter.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device,
4. The discharge lamp lighting device according to claim 1, wherein the high-frequency generating means includes a switching means, generates a high-frequency AC voltage according to switching of the switching means, and sets an on-period and an off-period of the switching means. It is characterized by having adjustable control means.

The present invention specifies a circuit configuration for adjusting the on-period and the off-period of the switching means to provide a sufficient rest period for the lamp current. That is, by appropriately adjusting the on-period and the off-period of the switching means, it is possible to superimpose a DC component on the high-frequency AC to make the output waveform asymmetrical in the positive and negative directions. As a result, it is possible to provide a sufficient rest period for the lamp current. it can.

According to a fifth aspect of the present invention, there is provided a discharge lamp lighting device according to any one of the first to fourth aspects, an airtight discharge vessel in which a discharge medium mainly composed of a rare gas is sealed, and At least one of the discharge lamps includes a pair of electrodes disposed on the outer surface of the discharge vessel, and a discharge lamp connected to an output terminal of the discharge lamp lighting device.

According to the present invention, a discharge lamp device is constituted by using the discharge lamp lighting device and the discharge lamp according to the first to fourth aspects. The discharge lamp lighting device and the discharge lamp may be mechanically integrated integrally, but may be separated from each other and electrically connected as needed.

According to a sixth aspect of the present invention, there is provided an apparatus according to the present invention, wherein a discharge lamp is provided as an illumination light source.
And the discharge lamp device described above.

According to the present invention, there is provided an airtight discharge vessel in which a discharge medium mainly composed of a rare gas is sealed, and at least one of which comprises a pair of electrodes disposed on the outer surface of the discharge vessel. The present invention is applicable to any equipment for utilizing the light emission of a discharge lamp connected to the end.

"Equipment main body" refers to a portion excluding the discharge lamp device from all elements constituting the equipment.

Examples of the device include a lighting device, an image reading device, a backlight device such as a liquid crystal device, a pointer of a vehicle-mounted instrument, and the like.

In particular, the discharge lamp used in the present invention is:
Since at least one of the electrodes is an outer surface electrode provided on the outer surface of the discharge vessel, it is easy to adopt a configuration in which the electrode is led out from a slit formed between the electrodes, and thus is suitable for an image reading device or a backlight device. It is.

However, if necessary, if the outer surface electrode is made transparent, the directivity of light emission is lost, so that it is possible to use the light emitting device without directivity as a lighting device which is easier to design.

[0052]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a first embodiment of a discharge lamp used in the discharge lamp lighting device of the present invention.

FIG. 2 is a side view of the same.

In the figure, 11 is a discharge vessel, 12a, 1
2b is an outer surface electrode, 13 is an insulating coating, 14 is an aperture,
Reference numeral 15 denotes a phosphor layer.

The discharge vessel 11 has a cylindrical shape closed at both ends, and contains xenon as a discharge medium inside.

The outer electrodes 12a and 12b are connected to the discharge vessel 11
Facing each other in parallel along the longitudinal direction of the discharge vessel 11
It is arranged on the outer surface of. Discharge vessel 1 with aluminum foil
1 is attached to the outer surface.

The insulating coating 13 comprises the outer electrodes 12a, 12b
And disposed outside the discharge vessel 11.

The aperture 14 is a slit for guiding light emission to the outside, and is provided between the outer electrodes 12 a and 12 b and the insulating coating 13.

FIG. 3 is a cross sectional view showing a second embodiment of the discharge lamp used in the discharge lamp lighting device of the present invention.

FIG. 4 is a schematic longitudinal sectional view.

In the figure, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description is omitted.

In this discharge lamp, one of a pair of electrodes is constituted by an external electrode 12 and the other is constituted by an internal electrode 16.

Since the external electrode 12 can be formed on the entire circumference of the discharge vessel 11 except for the portion of the aperture 14, the radiation noise can be significantly reduced by lighting the external electrode 12 while grounding it. it can.

The internal electrode 16 is located substantially coaxially with the discharge vessel 11 because both ends are sealed between both end faces of the discharge vessel 11. The internal electrode 16 is formed of a tungsten filament coil, and is energized and heated by a filament heating power supply 17 to emit thermoelectrons.

Thus, the outer electrode 12 and the inner electrode 1
A high-frequency AC power supply 18 is connected between the terminals 6 to discharge.

FIG. 5 is a circuit diagram showing a first embodiment of the discharge lamp lighting device according to the present invention.

In the figure, 21 is an AC power supply, 22 is a high frequency generator, and 23 is a discharge lamp.

The AC power supply 21 can be a commercial AC power supply.

The high frequency generating means 22 comprises a rectified DC power supply section 22a and an inverter section 22b.

The rectified DC power supply section 22a includes a rectifier circuit and a smoothing capacitor. The input terminal is connected to the AC power supply 21 to rectify and smooth the AC, and the rectified DC is output to the output terminal. Output.

The inverter section 22b includes a switching circuit 22b1, an output transformer 22b2, a first resonance circuit 22
b3 and a second resonance circuit 22b4.

The switching circuit 22b1 switches direct current, and is of a parallel switching type in a parallel inverter.

The output transformer 22b2 includes primary windings p,
It has a secondary winding s and a tertiary winding t, and the switching output of the switching circuit 22b1 is applied to the primary winding p.

The first resonance circuit 22b3 is composed of a parallel circuit of the primary winding p of the output transformer 22b2 and the first capacitor C1, has a resonance frequency of 28 kHz, and defines a sine wave fundamental.

The second resonance circuit 22b4 comprises a parallel circuit of the tertiary winding t of the output transformer 22b2 and the second capacitor C2, has a resonance frequency of 84 kHz, and regulates a third harmonic.

The discharge lamp 23 has a discharge vessel 23a in the form of a straight tube having an outer diameter of 8 mm and a length of 320 mm, and contains xenon gas inside. The pair of electrodes 23b and 23c
It is made of aluminum foil and attached to the outer surface of the discharge vessel 23a.

When the lamp is turned on with a DC output voltage of 24 V of the rectified DC power supply unit 22a and a lamp current of 40 mA, and the illuminance is measured using the discharge lamp 23 for reading, the lamp is turned on by applying a sine wave AC voltage. Was 20000 lx, but in the present embodiment, it was 30000 lx.

The radiation noise was within the standard.

FIG. 6 is a waveform diagram showing an output voltage waveform and a lamp current waveform of the high frequency generator in the first embodiment of the discharge lamp lighting device of the present invention.

In the figure, v is the output voltage, and i is the lamp current.

The waveform of the output voltage v of the high frequency generator has a steep rising and falling portion due to the third harmonic being superimposed on the fundamental wave.

On the other hand, a pause k is formed in the lamp current i. Since the afterglow occurs during the idle period, the luminous efficiency is improved.

FIG. 7 is a circuit diagram showing a second embodiment of the discharge lamp lighting device according to the present invention.

In the figure, the same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

The inverter section 22b of this embodiment is of a single-type voltage resonance type. Note that f is the switching circuit 22
The control circuit of b1, wherein the ON period and the OFF period, that is, the duty ratio are adjustable.

FIG. 8 is a waveform diagram showing an output voltage waveform and a lamp current waveform of the high frequency generator in the second embodiment of the discharge lamp lighting device of the present invention.

In the figure, v is the output voltage, and i is the lamp current.

The output voltage v is a repetition of a waveform having a high positive polarity peak value and a waveform having a negative polarity substantially trapezoidal low peak value.

As for the lamp current i, a positive current flows when the output voltage v rises in a voltage waveform having a high positive peak value, and a negative current flows when the output voltage v falls. And
When the output voltage is a substantially trapezoidal waveform having a low negative peak value of v, the lamp current does not flow, and a pause period k occurs.

Therefore, also in the present embodiment, a pause period k can be generated in the lamp current, so that an afterglow occurs during the pause period, and the luminous efficiency is improved.

FIG. 9 is a circuit diagram showing a third embodiment of the discharge lamp lighting device according to the present invention.

In the figure, the same parts as those in FIG.

In the present embodiment, the second inverter 22bB is replaced with the first inverter 22bB in place of the second resonance circuit 22b4 in FIG.
The output transformer 22b is connected in parallel with the inverter section 22bA.
2 through a third tertiary winding t. The oscillation frequency of the second inverter unit 22bB is specified to be three times the oscillation frequency of the first inverter unit 22bA.

Thus, in this embodiment, an output voltage similar to that shown in FIG. 5 can be obtained.

FIG. 10 is a conceptual sectional view of a reading apparatus showing an embodiment of the apparatus of the present invention.

In the figure, 31 is a reading device, 31a is a discharge lamp, 31b is light receiving means, 31c is a signal processing device and a lighting circuit, 31d is a document placing surface, 31e is a reflecting mirror,
Reference numeral 31f denotes a case for storing the above components. The lighting circuit of the discharge lamp 31a has the circuit configuration shown in FIG.

The reading apparatus is applicable to OA equipment such as a copying machine, an image scanner, and a facsimile. Note that the operation of the reading device is well-known, and a description thereof will be omitted.

[0099]

According to the first to tenth aspects of the present invention,
A discharge lamp having a sufficient rest period flows between the electrodes of a discharge lamp having at least one of a pair of electrodes disposed on the outer surface of a discharge vessel in which a discharge medium mainly containing a rare gas is sealed. High-frequency generating means for applying a high-frequency AC voltage whose waveform has been adjusted, after-glow occurs during a period in which the lamp current is stopped, thereby improving luminous efficiency and obtaining high illuminance, and pulse lighting. Thus, it is possible to provide a discharge lamp lighting device having less radiation noise as compared with the first embodiment.

According to the second aspect of the present invention, in addition to the above, the high frequency generating means applies the output voltage to the discharge lamp in which the rising and falling portions of the voltage waveform are sharpened by superimposing the harmonics on the fundamental wave. As a result, it is possible to provide a discharge lamp lighting device in which a quiescent period is generated in the lamp current and an afterglow is generated during the quiescent period to improve the luminous efficiency.

According to the third aspect of the present invention, in addition, the high frequency generating means includes the first resonance circuit resonating with the fundamental wave and the second resonance circuit resonating with the higher harmonic wave.
It is possible to provide a discharge lamp lighting device that generates an output voltage having a steep rising and falling portion of a voltage waveform with a simple circuit configuration.

According to the fourth aspect of the present invention, in addition, the high frequency generating means is provided with the control means for adjusting the on-time and the off-time of the switching means. Lamp device that can be adjusted as described above.

According to the fifth aspect of the present invention, there is provided a discharge lamp device having a discharge lamp in which at least one of a pair of electrodes is disposed on an outer surface of a discharge vessel in which a discharge medium mainly containing a rare gas is sealed. Can be provided.

According to the sixth aspect of the invention, it is possible to provide a device having the effects of the first to fifth aspects.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a discharge lamp used for a discharge lamp lighting device of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a sectional view showing a second embodiment of the discharge lamp used in the discharge lamp lighting device of the present invention.

FIG. 4 is a schematic longitudinal sectional view of the same.

FIG. 5 is a circuit diagram showing a first embodiment of the discharge lamp lighting device of the present invention.

FIG. 6 is a waveform chart showing an output voltage and a lamp current of a high-frequency generator in the first embodiment of the discharge lamp lighting device of the present invention.

FIG. 7 is a circuit diagram showing a second embodiment of the discharge lamp lighting device of the present invention.

FIG. 8 is a waveform chart showing an output voltage and a lamp current of a high-frequency generator in a second embodiment of the discharge lamp lighting device of the present invention.

FIG. 9 is a circuit diagram showing a third embodiment of the discharge lamp lighting device of the present invention.

FIG. 10 is a conceptual cross-sectional view of a reading device showing an embodiment of the device of the present invention.

FIG. 11 is a circuit diagram showing a discharge lamp lighting device disclosed in JP-A-9-199285.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... AC power supply 22 ... High frequency generating means 22a ... Rectified DC power supply part 22b ... Inverter part 22b1 ... Switching circuit 22b2 ... Output transformer 22b3 ... First resonance circuit 22b4 ... Second resonance circuit 23 ... Discharge lamp

Claims (6)

[Claims] An airtight discharge vessel in which a discharge medium mainly composed of a rare gas is enclosed, and at least one of the discharge vessels having a pair of electrodes disposed on an outer surface of the discharge vessel. A discharge lamp lighting device comprising: a high-frequency generating means for applying a high-frequency AC voltage whose waveform is adjusted so that a lamp current having a sufficient rest period flows. 2. The discharge lamp lighting according to claim 1, wherein the high frequency generating means outputs a high frequency AC voltage having a waveform which is flatter than the fundamental wave and whose rising and falling portions are steep, by superimposing harmonics. apparatus. 3. The high-frequency generation means includes a switching means, a first resonance circuit resonating with a fundamental wave, an output transformer, and a second resonance circuit magnetically coupled to the output transformer and resonating at a harmonic. The discharge lamp lighting device according to claim 1 or 2, wherein: 4. The high-frequency generating means includes a switching means, generates a high-frequency AC voltage in accordance with switching of the switching means, and has a control means capable of adjusting an on-period and an off-period of the switching means. The discharge lamp lighting device according to any one of claims 1 to 3, wherein 5. A discharge lamp lighting device according to claim 1, wherein an airtight discharge vessel in which a discharge medium mainly composed of a rare gas is sealed, and at least one of which is disposed on an outer surface of the discharge vessel. And a discharge lamp connected to an output terminal of the discharge lamp lighting device. 6. A discharge lamp device according to claim 5, wherein the discharge lamp is provided as an illumination light source.
An apparatus comprising: