JP2004111301A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device most suitable for illumination of an office, of which a rise time is short even under low temperatures, which does not flicker even when an ambient temperature is fluctuated, and generates a less heat value. <P>SOLUTION: The light source device including a window for removing visible light, is provided with a discharge container with discharge gas containing carbon monoxide sealed, a phosphor for radiating the visible light by ultraviolet irradiation, and a power supply means for supplying microwave power. The discharge gas radiates the ultraviolet light and visible light when excited by a microwave. The phosphor radiates the visible light when the ultraviolet light is irradiated, and the visible light is emitted from the window. The discharge container preferably transmits an ultraviolet ray and the phosphor is preferably arranged outside the discharge container. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light source device that emits visible light, which is preferably used for general lighting, for example.
[0002]
[Prior art]
Fluorescent lamps that emit visible light, especially white light, generally emit ultraviolet light due to the discharge of mercury vapor or a rare gas, and irradiate the phosphor layer with the generated ultraviolet light. Excites and emits visible light. Then, the visible light radiated into the discharge vessel of the fluorescent lamp is transmitted through the discharge vessel, led out to the outside, and used for illumination or the like.
[0003]
A hot cathode fluorescent lamp is used for general lighting. The hot cathode fluorescent lamp has a pair of internal electrodes provided inside a discharge vessel, and is filled with mercury and a rare gas. The electrodes arranged in the discharge vessel are composed of filaments, and thermions emitted from the filaments excite the rare gas to generate a discharge, and the heat generated by the discharge evaporates mercury in the discharge vessel. When the discharge by mercury vapor becomes dominant, ultraviolet rays having a wavelength of 154 nm or 265 nm are emitted from the excited mercury, and the ultraviolet rays irradiate the phosphor, and the phosphor emits visible light.
[0004]
A cold cathode fluorescent lamp used as a light source for a backlight of a liquid crystal panel or the like has substantially the same basic structure and light emitting operation mechanism as the above-described hot cathode fluorescent lamp. That is, a pair of internal electrodes is provided inside the discharge vessel, and mercury and a rare gas are sealed therein. Hot cathode fluorescent lamps use thermoelectrons radiated from filaments, while cold cathode fluorescent lamps use secondary electrons radiated from cold cathodes, and both fluorescent lamps differ in this respect.
[0005]
As described above, the fluorescent lamp in which mercury is sealed is to heat liquid mercury at room temperature and utilize vaporized mercury vapor.Therefore, when the fluorescent lamp is turned on, a desired power is supplied from power-on. There is a disadvantage that the time until light intensity is obtained (that is, the rise time) is long. In addition, since the amount of mercury vapor changes depending on the ambient temperature of the fluorescent lamp, there is a disadvantage that the ambient temperature characteristics are poor.
[0006]
As a fluorescent lamp in which mercury is not sealed, for example, a rare gas fluorescent lamp is known. A rare gas fluorescent lamp of an external electrode type has only a rare gas sealed inside a discharge vessel, and a pair of external electrodes is disposed on the outer surface of the discharge vessel, and a high voltage of several kV order is applied to the electrodes. , Causing a dielectric barrier discharge. Excimer molecular emission emitted from the rare gas obtained by such discharge excites the phosphor to emit visible light from the phosphor.
Further, in an internal electrode type rare gas fluorescent lamp, the electrode is a cold cathode, and the phosphor is irradiated with ultraviolet light generated by discharge of the rare gas, and visible light is emitted from the phosphor.
Such a rare gas fluorescent lamp that does not contain mercury has the advantages of a short rise time and excellent ambient temperature characteristics, but has a higher luminous efficiency than a fluorescent lamp that contains mercury. It is not suitable as a light source for general illumination because it is low. Therefore, it is widely used in fields such as a reading light source of a copying machine.
[0007]
[Patent Document 1] Japanese Patent Application Laid-Open No. 10-188989 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-351572 [Patent Document 3] Japanese Patent Application Laid-Open No. 9-92227 [Patent Document 4] Japanese Patent Application Laid-Open No. 5-251407 ]
[Problems to be solved by the invention]
Recently, from the viewpoint of energy saving, there are not a few offices in which lighting is used only when it is necessary. Therefore, in fluorescent lamps, lighting is frequently used repeatedly.
As a result, in a fluorescent lamp in which mercury is sealed, there is a disadvantage that, compared to a case where the lamp is continuously lit, the mercury is apt to be insufficiently evaporated and a sufficient illuminance cannot be obtained immediately after the lamp is lit. It is becoming more pronounced.
[0009]
In addition, when the fluorescent lamp is arranged near the air outlet of the cooling, the temperature of the discharge vessel of the fluorescent lamp is easily reduced, and it becomes impossible to obtain a desired mercury vapor, and the rise time is reduced. It will be longer and flicker.
In addition, the above-mentioned problem similarly occurs not only in office lighting but also in lighting devices used at low temperatures, for example, lighting in a large refrigerator or a large freezer.
[0010]
In view of the above circumstances, even if we consider using rare gas fluorescent lamps that do not contain mercury for the purpose of shortening the rise time and improving the stabilization of illuminance, the output of rare gas fluorescent lamps can be increased. To achieve this, it is necessary to increase the size of the discharge vessel and apply a higher voltage than before, which is actually very difficult.
Therefore, the problem to be solved by the present invention is that the rise time is short even at a low temperature, no flicker occurs even if the ambient temperature fluctuates, and the calorific value is small. A light source device is provided.
[0011]
[Means for Solving the Problems]
Therefore, the light source device of the present invention is a light source device having a window for extracting visible light, a discharge vessel filled with a discharge gas containing carbon monoxide, and a fluorescent light emitting visible light by ultraviolet light irradiation. And a power supply means for supplying microwave power, wherein the discharge gas emits ultraviolet light and visible light when excited by the microwave, and the phosphor emits the ultraviolet light. Irradiates visible light, and emits visible light from the window.
Further, it is preferable that the discharge vessel has an ultraviolet transmittance, and the phosphor is disposed outside the discharge vessel.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a light source device according to an embodiment of the present invention, and is a cross-sectional view schematically showing a configuration example assuming an office lighting device.
[0013]
The microwave oscillator 11 is provided at one end of the waveguide 12, and generates a microwave of 2.45 GHz. The generated microwave is radiated to the waveguide 12 by an antenna (not shown), and is branched from the waveguide 12 to the resonators 13a, 13b, and 13c and propagated.
Windows 14a, 14b, and 14c are formed by metal mesh on the lower bottom surface of the resonators 13a, 13b, and 13c on the paper surface, and lamps 20a and 20b are provided in hollow portions inside the resonators 13a, 13b, and 13c. , 20c are stored.
[0014]
A directional coupler 15 is provided between the microwave oscillator 11 and the waveguide 12. When the lamps 20a, 20b, and 20c are broken and the lamps are turned off due to failure or the like, the directional coupler 15 loses the matching between the magnetron and the lamp load, increases reflected waves, and reflects the reflected waves. This is for preventing a problem such as a wave destroying the microwave oscillator 11 and is intended to prevent a reflected wave from returning to a power supply.
[0015]
FIG. 2 is an enlarged view of the lamp according to the present invention, and is a cross-sectional view of the discharge vessel cut in the tube axis direction.
The lamp 20 a has a discharge vessel 21 in which carbon monoxide (CO) as a discharge gas is sealed, an outer tube 22 disposed outside the discharge vessel 21, and an inner surface of the outer tube 22. Phosphor 23. The discharge vessel 21 is a closed vessel in which both ends of a cylindrical tube having an outer diameter of 26 mm and a length of 150 mm are sealed, and is made of a dielectric material having transparency to ultraviolet rays, specifically, synthetic quartz. . The discharge vessel 21 is filled with, for example, 130 Pa of carbon monoxide as a discharge gas at room temperature. Note that a suitable inert gas may be mixed with the carbon monoxide.
[0016]
The outer tube 22 is made of a material that does not have transparency to ultraviolet light having a wavelength of 350 nm or less, and is made of, for example, fused quartz, borosilicate glass, aluminosilicate glass, or the like, having an inner diameter of about 30 mm, an outer diameter of 34 mm, and a length of 160 mm. It is.
[0017]
No electrodes are provided inside the discharge vessel 21, and power is supplied by microwaves.
This reason is closely related to the behavior of carbon monoxide during discharge.
During discharge, carbon monoxide is separated into carbon and oxygen, and the separated carbon adheres and accumulates on the inner surface of the discharge vessel 21 to cause an undesired phenomenon that light transmittance is significantly reduced. As a result, the light transmittance of the discharge vessel is impaired, but on the other hand, oxygen separated from carbon monoxide etches the deposited carbon, floats in the discharge vessel, and the light transmittance of the discharge vessel 21 is reduced. When a certain amount of carbon deposits and reaches an equilibrium state, a stable discharge can be maintained. That is, in the discharge of carbon monoxide, an equilibrium state is reached in the reaction with the inner surface of the discharge vessel 21.
[0018]
However, when the electrode is disposed in the discharge vessel, tungsten generally used as a discharge lamp electrode has a property of absorbing carbon, so carbon dissociated by the discharge is absorbed by the electrode, This results in a discharge with a very high oxygen ratio, and as a result, the desired ultraviolet light is not emitted. That is, in the discharge of the carbon monoxide gas, an equilibrium state is not reached in the reaction with the electrode.
The lamp in the light source device according to the present invention has a structure in which no electrode is provided inside the discharge vessel, and therefore, since there is no carbon absorption by the electrode as described above, the emission of ultraviolet light is maintained, and the phosphor is used. Can be supplied stably with the amount of ultraviolet radiation to be applied to the substrate, and as a result, the output of visible light can be increased.
[0019]
When microwave power of 50 to 500 W is applied from the microwave oscillator 11 to the waveguide 12, the carbon monoxide gas reaches a discharge state, and ultraviolet rays originating from the 4th positive molecular line, that is, 250 Ultraviolet light in the range of 300 nm and a wavelength of 200 nm or less is emitted.
Further, at the same time as the ultraviolet light, visible light having a wavelength in the range of 400 to 800 nm is emitted.
[0020]
The visible light and the ultraviolet light obtained as described above pass through the synthetic quartz and are emitted to the outside of the discharge vessel 21.
[0021]
Then, ultraviolet light having a wavelength in the range of 250 to 300 nm and a wavelength of 200 nm or less that has passed through the discharge vessel 21 irradiates the phosphor 23 applied to the inner surface of the outer tube 22.
[0022]
The phosphor 23 is excited in the range of wavelengths from 250 nm to 350 nm and on the short wavelength side in response to ultraviolet rays obtained from the discharge of carbon monoxide described above, that is, ultraviolet rays having a wavelength of 250 to 350 nm and ultraviolet rays having a wavelength of 200 nm or less. The one that has a spectrum is used.
An example of a phosphor, halo phosphate phosphors _{((Sr, Ca) 10 (} PO 4) 6 C l2: Eu 2+ , etc.), phosphate phosphor _{(Sr 2 P 2 O 7:} Eu 2+ , etc.) , silicate phosphor _{(Sr 2 Si 3 O 8 ·} 2SrC l2: etc. ^{Eu 2+),} and the like. Although the dominant wavelength of light emission of the phosphor varies depending on the phosphor, visible light emission in a wavelength range of 400 to 800 nm can be obtained by a combination of several kinds of phosphors.
[0023]
Then, the visible light of 400 to 800 nm generated from the discharge of carbon monoxide from the outer tube 22 of the lamp 20 and the visible light of 400 to 800 nm obtained by irradiating the phosphor 23 with ultraviolet light are transmitted through a window in the lighting device. It will be emitted from 14a, 14b, 14c.
[0024]
The emission of the visible light by the phosphor is emitted from the window formed in the resonator together with the visible light generated by the discharge of the discharge gas, and the office can be illuminated brightly and clearly.
[0025]
As described above, according to the lighting device of the present invention, visible light is obtained by exciting the discharge vessel filled with carbon monoxide with microwaves, and simultaneously emitted ultraviolet light is made visible by the phosphor. By converting the light into light, the output of visible light can be further increased. As a result, it is possible to obtain a high-output light source device in which the illuminance is stable from the initial stage of lighting of the lamp and which has excellent rising characteristics and ambient temperature characteristics.
[0026]
In the present invention, it is needless to say that the present invention is not limited to the above configuration, but can be appropriately changed. For example, in the above embodiment, the fluorescent substance and the discharge vessel are applied to an outer tube separate from the discharge vessel, but may be applied directly to the outer surface of the discharge vessel. Further, a fluorescent material may be applied to a plate-like member having light transmissivity and arranged in the resonator. In addition, if a phosphor with low gas adsorption is used, the phosphor can be applied to the inner surface of the discharge vessel. The shape of the discharge vessel is not limited to a tubular shape as described above, and a rectangular box shape may be used. Further, the same operation / effect can be obtained by a method of lighting by applying a high frequency of MHz instead of microwaves. Therefore, it is also possible to light with high frequency power of MHz band instead of microwave power. . Thus, from the viewpoint of efficiency, it is better to light up with microwaves. In the case of lighting with high frequency power in the MHz band, the lamp has a configuration in which electrodes are arranged outside the discharge vessel.
[0027]
【Example】
The light emitting state of the light source device according to the above embodiment will be described based on examples.
When microwave power of traveling wave power of 300 W was applied to the waveguide by a microwave oscillator composed of a magnetron, it was visually confirmed that carbon monoxide started discharging and visible light was emitted from the discharge vessel. Was done.
[0028]
The radiated light amount of the light radiated by the discharge of carbon monoxide was measured by a radiated light amount measuring device, and the indicated value was 97 mW / cm ² .
The emitted light emitted by the discharge of carbon monoxide has a chromaticity point (x, y) = line (0.29, 0.32), a color temperature of 8300 K, an average color rendering index (Ra) of 96, and general lighting. It was found that it was a visible light which could be used sufficiently and that it had good characteristics.
FIG. 3 shows the emission spectrum of the emitted light in the visible region. The vertical axis is the relative value of the amount of radiation.
[0029]
Further, an ultraviolet cut filter was attached to the sensor for measuring the amount of emitted light, and the amount of emitted light was measured. The indicated value was 52 mW / cm ² . That is, it was confirmed that the same ultraviolet output as the visible light output was emitted.
When this emitted light was applied to a phosphor (a general phosphor having an excitation wavelength center wavelength of 254 nm), strong visible light emission was obtained from the phosphor.
[0030]
Further, a phosphor was applied to the outer surface of the discharge vessel, and the amount of radiation including the light emitted from the phosphor was measured. As a result, visible light radiation of 121 mW / cm ² was obtained.
[0031]
When microwave power was applied in a state where the ambient temperature of the light source device was set to about 0 ° C., the light amount instantaneously rose, and no flickering or the like occurred. As described above, according to the light source device according to the present embodiment, even when the ambient temperature is relatively low, a high-output light source device having excellent startup characteristics can be obtained.
[0032]
[Comparative example]
A lamp having the same configuration as that shown in FIG. 2 is provided with a pair of external electrodes on the outer surface of the discharge vessel, and is lit by applying a voltage of 70 W, a peak voltage of 3.5 kV (900 mA peak voltage), and a frequency of 70 kHz. did. As a result, a light blue discharge was generated, but ultraviolet light originating from the 4th positive molecular line was weak and sufficient visible light could not be obtained.
[0033]
【The invention's effect】
As described above, visible light is obtained by discharge-exciting the discharge vessel filled with carbon monoxide with microwaves, and simultaneously the emitted ultraviolet light is converted into visible light by the fluorescent substance, so that the rising characteristics and A high-output visible light source having excellent ambient temperature characteristics can be obtained, and a light source device suitable for general illumination can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a light source device according to an embodiment of the present invention.
FIG. 2 is a sectional view in the tube axis direction of the lamp.
FIG. 3 is a continuous light emission spectrum of a lamp according to an example due to carbon monoxide discharge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Microwave oscillator 12 Waveguide 13a, 13b, 13c Resonant chamber 14a, 14b, 14c Window 15 Directional coupler 16 Non-reflection termination 20a, 20b, 20c Lamp 21 Discharge container 22 Outer tube 23 Phosphor

Claims (2)

A light source device having a window for extracting visible light,
A discharge vessel filled with a discharge gas containing carbon monoxide, a phosphor that emits visible light by ultraviolet light irradiation, and a power supply unit that supplies microwave power,
The discharge gas emits ultraviolet light and visible light by being excited by the microwave,
The phosphor emits visible light by being irradiated with the ultraviolet light,
A light source device, wherein visible light is emitted from the window. The light source device according to claim 1, wherein the discharge container has an ultraviolet transmission property, and the phosphor is disposed outside the discharge container.

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