JPH0794150A - Rare gas discharge lamp and display device using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rare gas discharge lamp and a display device that emit ultraviolet light having a wavelength equal to or close to that of the case of using mercury without using mercury, and improve luminous efficiency. A rare gas discharge lamp in which at least one kind of rare gas for light emission and at least one kind of halogen gas are enclosed in an arc tube 1 and mercury is not used. The ultraviolet ray is emitted from each of the rare gas and the halogen, and the ultraviolet ray in the wavelength range equivalent to that of mercury is emitted, so that the emission intensity of the ultraviolet ray can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare gas discharge lamp called a mercury-less fluorescent lamp which does not use mercury as a light emitting substance, and a display device using the rare gas discharge lamp.

[0002]

2. Description of the Related Art Generally, a fluorescent lamp is formed by forming a phosphor coating on the inner surface of an arc tube having electrodes sealed at both ends, and filling the arc tube with a rare gas such as mercury and argon. By discharging the mercury between the electrodes, the mercury in the arc tube is evaporated and the mercury atoms are excited and ionized.
This is the mercury resonance line emitted when this mercury atom is excited 1
The 85 nm and 254 nm ultraviolet rays are converted into visible light by a phosphor formed on the tube wall, and this visible light is emitted to the outside of the arc tube. Therefore, mercury is essential for fluorescent lamps of the type described above. However, the lamp using mercury has the problem of resource depletion,
There is a social problem of environmental pollution when mercury is abandoned,
Lamps that do not use mercury are being developed.

As such a mercury-free lamp, that is, a mercury-less lamp, xenon Xe is used instead of mercury.
Is known as a rare gas discharge lamp in which the fluorescent substance is excited by the ultraviolet rays emitted by xenon to emit visible light, so-called xenon rare gas discharge lamp, which is already used as a display light source for OA equipment. Has been done.

However, in the conventional xenon rare gas discharge lamp, electrodes are sealed inside the end portions of the arc tube, and discharge is generated between these internal electrodes to sustain this discharge, and the xenon atom is generated by this positive column. It excites (Xe ^* ) to emit ultraviolet rays having a wavelength of 147 nm. The ultraviolet ray emission form by such discharge has a large self-absorption effect at 147 nm, the effective utilization rate of ultraviolet rays is low, and since this wavelength is far from 185 nm which is one resonance line of mercury, it is excited by the resonance line of mercury. Therefore, when a phosphor developed to emit visible light is used, the luminous efficiency of visible light is not good. For example, the above xenon noble gas discharge lamp can be used as a cerium-activated yttrium silicate phosphor Y ₂ SiO ₅ :
When it is applied to Ce, it has a drawback that only about 10% of the luminous efficiency can be obtained even with the same input as compared with the ultraviolet light emission by mercury.

In view of the above, there has been proposed a lamp in which electrodes are formed on the outer wall of the arc tube and discharge is generated in the arc tube by the external electrodes. When the electrode is an external electrode, this causes so-called silent discharge, and a minute discharge occurs on the inner surface of the tube wall of the arc tube. In other words, in this product, the tube wall acts as a capacitor, and a minute discharge like a whiskers occurs on the surface of the tube wall. This is because the insulating action of the glass immediately extinguishes the discharge, and the discharge continues like a positive column. In addition, a discharge that converges does not occur. According to such a silent discharge, a large amount of excimer (excimer = one molecule in the ground state and one molecule in the excited state) associate with each other from the xenon encapsulated in the arc tube as shown in the following [Chemical formula 1]. The resulting dimer) can be generated.

[0006]

[Chemical 1]

The above-mentioned xenon excimer (Xe ₂ ^* ) has a characteristic that it emits ultraviolet rays of 173 nm. In this wavelength region, there is little self-absorption, and one resonance line of mercury, 185 nm.
As compared with the internal electrode type xenon rare gas discharge lamp, the amount of emitted ultraviolet light increases and the emission intensity of visible light increases.

[0008]

However, in the xenon noble gas fluorescent lamp for performing the silent discharge by using the external electrodes as described above, the xenon excimer emits ultraviolet rays of 173 nm, and therefore the luminous efficiency of visible light is high. However, the emission of ultraviolet rays does not occur in the vicinity of 254 nm, which is the other resonance line of mercury, so that the excitation function of the phosphor in this portion is not effectively utilized. Therefore, there is still a problem that the efficiency is low.

The present invention has been made in view of the above circumstances. The object of the present invention is not to use mercury,
However, it is an object of the present invention to provide a rare gas discharge lamp that emits ultraviolet rays having a wavelength equal to or close to that of the case of using mercury to improve luminous efficiency, and a display device using the rare gas discharge lamp.

[0010]

According to a first aspect of the present invention, there is provided a rare gas discharge lamp in which a discharge rare gas is enclosed in an arc tube and ultraviolet rays emitted from the rare gas are emitted. The above rare gas for discharge and at least one kind of halogen gas are enclosed. The invention of claim 2 is characterized in that a phosphor coating is formed on the inner surface of the arc tube. The invention of claim 3 is characterized in that discharge is generated in the arc tube by an electrode provided outside the arc tube. The invention according to claim 4 is characterized in that the filling pressure of the rare gas for discharge is 1000 Pa or more. The invention of claim 5 is characterized in that the discharge rare gas is xenon. The invention of claim 6 is characterized in that the halogen gas is filled at a filling pressure equal to or lower than the vapor pressure specific to the halogen at 20 ° C.
The invention of claim 7 is characterized in that the halogen gas is at least one of bromine and iodine. Claim 8
The invention according to claim 1, wherein the phosphor coating is not formed on the inner surface of the arc tube, and the rare gas discharge lamp according to claim 1, which is provided outside the discharge lamp and emits light by receiving ultraviolet rays emitted from the discharge lamp. A display device comprising: a display unit having a light body layer.

[0011]

According to the inventions of claims 1 and 2, since the rare gas for discharge and the halogen are enclosed in the arc tube, the rare gas atom, the excimer of the rare gas, the excimer of the halogen and the compound of the rare gas and the halogen are contained. Ultraviolet light is emitted from each of the excimers and the like, and ultraviolet light in a wavelength range equivalent to that of mercury is emitted, so that the emission intensity of visible light can be increased. According to the third aspect of the invention, so-called silent discharge is generated in the arc tube by the electrode provided outside the arc tube, and a large amount of excimer is generated, so that the ultraviolet ray output is increased.

According to the fourth aspect of the present invention, since the filling pressure of the rare gas for discharge is 1000 Pa or more, a large amount of excimer of the compound of the rare gas for discharge and halogen can be generated. According to the invention of claim 5, since the rare gas for discharge is xenon, the ultraviolet ray generation efficiency is good. According to the invention of claim 6, since the halogen gas is sealed at a sealing pressure lower than the vapor pressure specific to the halogen at 20 ° C., the vapor pressure of the halogen does not change even when the temperature exceeds 20 ° C. Therefore, the change in the amount of halogen light emission due to the temperature change is small, and the change in the light output due to the temperature change can be prevented. According to the invention of claim 7, since at least one of bromine and iodine is used as the halogen gas, the generation efficiency of ultraviolet rays is good. According to the invention of claim 8,
Even in rare gas discharge lamps that do not form a phosphor coating on the inner surface of the arc tube, the phosphor provided in the display section is excited to emit visible light when receiving the ultraviolet rays emitted from this discharge lamp. Since the rare gas discharge lamp as a light source has a high ultraviolet output, the display performance is high.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS. In this valve 1, xenon Xe, argon Ar, krypton Kr, neon N
At least one rare gas selected from e and the like and at least one halogen group element selected from bromine Br, iodine I, chlorine Cl, fluorine F, and the like are enclosed.
In the case of this embodiment, xenon Xe is enclosed as a rare gas and bromine Br is enclosed as a halogen. Xenon X
The e gas is sealed at 1000 Pa or more, for example, 10000 Pa (partial pressure), and the bromine Br as a halogen has a vapor pressure (20,000) intrinsic to bromine when the temperature reaches 20 ° C.
Pa) or less, for example, 2000 Pa (partial pressure).

External electrodes 3 and 4 are provided on the outer surface of the bulb 1 so as to face each other. These external electrodes 3 and 4 have a band structure along the axial direction of the bulb 1, and are attached to the outer surface of the bulb 1 by means such as applying a conductive paint or joining a conductive metal piece. There is. These external electrodes 3 and 4 are connected to an AC power supply 5. This AC power source 5 has a frequency of several kHz to several tens of kHz.
It is a high frequency light source that supplies a sine wave of Hz.

The mercury-free halogen-containing xenon rare gas discharge lamp having such a structure has a frequency of several kHz between the external electrodes 3 and 4.
When a high frequency sine wave of several tens of kHz, for example, 20 kHz is supplied, many whisker-like silent discharges are generated on the inner surface of the tube wall. This discharge generates a local minute glow discharge on the inner surface of the tube wall, and this glow discharge is immediately extinguished,
Another minute glow discharge is generated at another point, and this glow discharge is immediately extinguished. Such a minute discharge is generated over the entire inner surface of the tube wall, and becomes a silent discharge as if the entire discharge is even.

By such discharge, the xenon Xe and bromine Br enclosed in the arc tube 1 exist in the form of xenon atom (Xe ^* ) and bromine atom (Br ₂ ^* ), respectively, and the excimer of these xenon ( Xe ₂
^* ), And in the form of an excimer (XeBr ^* ) of a compound of xenon Xe and bromine Br. Moreover, the xenon atom Xe is an excimer (Xe ₂ ^* ) as shown in [Chemical formula 1].
This excimer (Xe ₂ ^* ) repeats the reaction of ionization as shown in the following [Chemical formula 2].

[0017]

[Chemical 2]

The excimer (XeBr ^* ) of the compound of xenon Xe and bromine Br repeats association and separation as shown in the following [Chemical formula 3].

[0019]

[Chemical 3]

Further, the xenon atom (Xe ^* ) has a wavelength of 1
The xenon excimer (Xe ₂ ^* ) emits an ultraviolet ray having a wavelength of 173 nm while emitting an ultraviolet ray of 47 nm. Further, the excimer of bromine (Br ₂ ^* ) emits an ultraviolet ray of 289 nm, and the excimer of xenon Xe and bromine Br (XeBr ^* ) emits an ultraviolet ray of 283 nm, as shown in [Table 1] below.

[0021]

[Table 1]

That is, in the arc tube 1, ultraviolet rays having a wavelength of 147 nm emitted from a xenon atom (Xe ^* ) and a wavelength of 17 emitted from an excimer (Xe ₂ ^* ) of xenon.
3 nm UV, 289 nm UV emitted from bromine excimer (Br ₂ ^* ) and xenon Xe
And bromine Br excimer (XeBr ^* ) emits ultraviolet light having a wavelength of 283 nm at the same time.

Therefore, ultraviolet rays close to the resonance lines of 185 nm and 254 nm, which are the resonance lines of mercury, are emitted, and a phosphor developed to emit visible light by being excited by the resonance line of mercury was used. In this case, the luminous efficiency of visible light is improved.

For example, when the cerium-activated yttrium silicate phosphor Y ₂ SiO ₅ : Ce is used as the phosphor coating 2, it is 1% as compared with the lamp not mixed with bromine Br.
An efficiency improvement of 5% or more was recognized.

Further, in the case of the present embodiment, the bromine Br is sealed in such a state that when the temperature reaches 20 ° C., it becomes equal to or lower than the intrinsic vapor pressure of bromine (20,000 Pa), for example, 20,000 Pa (partial pressure). Therefore, the ambient temperature is 2
There is no source of bromine even at temperatures above 0 ℃, 20,000
It does not significantly exceed Pa, and the vapor pressure hardly changes up to about 200 ° C. On the other hand, when bromine Br ₂ is excessively enclosed, the vapor pressure has the property of changing with temperature, so the ambient temperature changes and the temperature of the coldest part changes from startup to stabilization. In the process of bromine Br
The vapor pressure of ₂ changes, which changes the light emission state of halogen, which changes the light output. That is, when bromine is excessively enclosed in the arc tube 1 in a liquid state, the characteristic B in FIG.
As shown in, the evaporation of bromine is promoted as the temperature rises, and the evaporation pressure of bromine increases rapidly.
0 Pa, about 70,000 Pa at 50 ° C, about 2 at 75 ° C
At 00000 Pa and 100 ° C., it rises to about 500000 Pa. Therefore, the luminescence amount of bromine changes as the temperature of the tube wall changes, and the total light output changes accordingly.

However, in the present embodiment, the encapsulation pressure of bromine Br is set to 200 ° C. when the temperature is 20 ° C.
00 Pa) or less, for example, 20000 Pa (partial pressure), so even if the temperature rises to about 200 ° C., there is no bromine vapor supply source, so as shown by the characteristic A in FIG. There is almost no change, and therefore, there is no change in the luminescence amount of bromine, and the change in the total light output can be reduced. From this, it is possible to reduce changes in the ambient temperature and changes in the light output when the luminous flux rises.

In order to generate the silent discharge, it is effective to apply a high frequency of several kHz to several tens of kHz by a sine wave and light it with a pulsed current. However, when the lighting frequency is increased to about several MHz, the discharge continues, but a decrease of 283 nm is observed due to the XeBr ^* excimer. This is because the pulsed discharge cannot be performed due to the increase in the lighting frequency, and the so-called rest period is shortened, so that there is no time allowance for XeBr ^* to be separated into Xe and Br, and therefore a decrease of 283 nm occurs. Guessed. From this point, XeBr ^*
It is effective to supply a pulsed lamp current in order to obtain the intensity of 283 nm by the decomposition of the excimer, and it is preferable to apply a high frequency of several kHz to several tens of kHz by a sine wave.

Further, it is desirable that the filling pressure of the rare gas is 1000 Pa or more. When the filling pressure of the rare gas is less than 1000 Pa, the decrease of 283 nm by the XeBr ^* excimer is observed. It is considered that this is because the number of xenon atoms Xe decreases, the chance of collision between xenon Xe and bromine Br decreases, and the number of XeBr ^* excimers generated decreases. The rare gas filling pressure is 300,000 Pa.
It is known that it may be raised to some extent.

In the above embodiment, xenon X is used as the rare gas.
While e was used and bromine Br was used as a halogen, an example in which iodine I was used instead of bromine Br as a halogen will be described. With iodine I, the wavelength 147 nm emitted from the xenon atom (Xe ^* ) and 173 nm emitted from the excimer of xenon (Xe ₂ ^* )
In addition to the ultraviolet rays of the above, as can be seen from [Table 1], ultraviolet rays having a wavelength of 342 nm emitted from the excimer of iodine (I ₂ ^* ) and wavelengths of 253 nm emitted from the excimer of the compound of xenon Xe and iodine I (XeI ^* ). Ultraviolet rays are emitted. Therefore, as the phosphor coating 2, 400
The intensity of visible light is increased by using an optical body having a wide excitation sensitivity in the wavelength range of nm or less, for example (Ba, C
a, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu phosphor is effective.

In addition to the xenon Xe, the rare gas may be at least one selected from the above-mentioned argon Ar, krypton Kr, neon Ne, etc., and the halogen is bromine Br or iodine I. Chlorine Cl and fluorine F outside
It may be at least one kind of halogen group element selected from the above, and the emission wavelengths of these excimers and excimers obtained by the combination thereof are as shown in [Table 1].

Furthermore, the present invention is not limited to a lamp in which silent discharge is performed by the external electrodes 3 and 4. For example, in FIG.
And, as shown in FIG. 5, a cold cathode 7,
Even in the case of a cold cathode rare gas discharge lamp in which 7 is sealed, excimers can be generated and ultraviolet light can be emitted in a plurality of wavelength regions. In FIG. 4, reference numeral 8 is a current limiting means. An example of an experiment in which the relationship between the temperature of the coldest part of the bulb and the relative total luminous flux is measured in the rare gas discharge lamp having the structure as shown in FIG. 4 will be described. A phosphor coating 2 made of LaPO ₄ is formed on the inner surface of a bulb 1 having an inner diameter of 8 mm.
000 Pa of xenon and 8000 Pa of bromine at 20 ° C. (the vapor pressure corresponds to the vapor pressure of 0 ° C.) were enclosed in a gas state. When a high frequency of 20 kHz was applied with a lamp current of 20 mA, an efficiency improvement of 20% or more was recognized as compared with a lamp not mixed with bromine Br.

When bromine is excessively enclosed in a liquid state, as shown by the characteristic D in FIG. 5, the change in the relative total luminous flux is large with the change in the temperature of the coldest part.
In the case of the present invention in which the enclosed pressure is regulated to 8000 Pa at 0 ° C., as shown by the characteristic C in FIG. 5, there is little change in the relative total luminous flux due to the change in the temperature of the coldest part, and therefore the change in the optical output due to the temperature change. It was confirmed that there were few.

The present invention can also be carried out in a rare gas discharge lamp in which one electrode is an internal cold cathode and the other electrode is an external electrode. Furthermore, in the case of the above embodiment, the phosphor coating 2 is formed on the inner surface of the arc tube bulb 1,
Although the ultraviolet rays emitted from the rare gas for discharge and the halogen gas are converted into visible light by the phosphor coating 2 and emitted, the discharge lamp does not always emit visible light and emits ultraviolet rays. The discharge lamp may be a rare gas discharge lamp. Although not shown, the ultraviolet light emitted from such a rare gas is used as a light source of an ultraviolet exposure device or is irradiated to a display portion such as a display plate provided outside the rare gas discharge lamp. It can also be used in a device that converts the visible light into a predetermined visible light by the phosphor layer formed on the display. Therefore, in a rare gas discharge lamp in which a discharge rare gas is enclosed in the arc tube and ultraviolet rays emitted from this rare gas are emitted,
It may be a rare gas discharge lamp in which at least one kind of rare gas for discharge and at least one kind of halogen gas are enclosed in the arc tube.

[0034]

As described above, according to the present invention, since the rare gas for discharge and the halogen are enclosed in the arc tube, the rare gas atom, the excimer of the rare gas, the excimer of the halogen and the compound of the rare gas and the halogen are included. The excimer or the like emits ultraviolet rays, respectively, and emits ultraviolet rays in a wavelength range equivalent to that of mercury, so that the emission intensity of ultraviolet rays can be increased. Therefore, it is not necessary to use mercury, and it is possible to solve social problems such as resource and environmental pollution.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a rare gas discharge lamp according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a characteristic diagram showing changes in vapor pressure of bromine due to changes in temperature.

FIG. 4 is a sectional view showing a schematic configuration of a rare gas discharge lamp according to another embodiment of the present invention.

FIG. 5 is a characteristic diagram showing how the total luminous flux changes as the temperature of the coldest part of the bulb changes.

[Explanation of symbols]

1 ... Arc tube 2 ... Fluorescent film 3, 4 ...
External electrode 5 ... High frequency power supply 7 ... Cold cathode

Claims (8)

[Claims] 1. A rare gas discharge lamp in which a rare gas for discharge is sealed in an arc tube and ultraviolet rays emitted from the rare gas are discharged, wherein at least one kind of the rare gas for discharge and at least one kind are contained in the arc tube. A rare gas discharge lamp characterized by being filled with the halogen gas of. 2. The rare gas discharge lamp according to claim 1, wherein a phosphor coating is formed on the inner surface of the arc tube. 3. The rare gas discharge lamp according to claim 1, wherein discharge is generated in the arc tube by an electrode provided outside the arc tube. 4. The filling pressure of the rare gas for discharge is 1000 P.
It is a or more, The claim 1 or Claim 2 characterized by the above-mentioned.
Noble gas discharge lamp described in. 5. The rare gas discharge lamp according to claim 1, wherein the rare gas for discharge is xenon. 6. The rare gas discharge lamp according to claim 1, wherein the halogen gas is filled at a filling pressure equal to or lower than a vapor pressure specific to the halogen at 20 ° C. 7. The rare gas discharge lamp according to claim 1, wherein the halogen gas is at least one of bromine and iodine. 8. A rare gas discharge lamp according to claim 1, wherein a phosphor coating is not formed on the inner surface of the arc tube, and light is emitted by receiving ultraviolet rays emitted from the discharge lamp provided outside the discharge lamp. A display device comprising: a display unit having a phosphor layer.