JPH08273620A - Fluorescent lamp and lighting apparatus thereof and light source apparatus and liquid crystal display apparatus employing thereof - Google Patents

Abstract

PURPOSE: To provide a fluorescent lamp, a fluorescent lamp containing mercury and xenon in air-tightly, with improved characteristics of rise time of luminous fluxes at the time of starting and light emitting efficiency, a lighting apparatus of the lamp, and a light source apparatus and a liquid crystal apparatus. CONSTITUTION: Regarding a fluorescent lamp 1 in which mercury and a rare gas of mainly xenon are sealed in a light emitting tubular bulb 2; the lamp has a characteristic that a phosphor body layer 3 containing a phosphor body 3a which emits light by receiving ultraviolet-ray radiated from mercury and a phosphor body 3b which emits light by receiving ultraviolet-ray with 200nm or shorter wavelength is formed. Consequently, at the time of starting at low temperature, the xenon-exciting type phosphor body emits visible light-ray by ultraviolet-ray with 200nm or shorter wavelength radiated mainly xenon and thus luminous fluxes at the time of starting can be increased. Moreover, since the mercury vapor pressure rises when the lamp reaches a stable lighting state, the mercury-exciting type phosphor body also emits visible light-ray and light emitting efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp containing mercury and xenon gas, a lighting device for lighting the lamp, a light source device using the same, and a liquid crystal display device.

[0002]

2. Description of the Related Art For example, a small cold cathode fluorescent lamp is used as a backlight of a liquid crystal display device or as a display pointer of various meters. A conventional cold cathode fluorescent lamp contains mercury as a light emitting substance and argon or neon as a rare gas. The vaporized mercury atoms are ionized and excited to emit 185 nm and 254 nm of mercury emission lines. The ultraviolet rays are emitted, and the ultraviolet rays are converted into visible light by a phosphor and emitted to the outside. Therefore, in the conventional lamp, the luminous efficiency depends on the vapor pressure of mercury, and when the lamp power is low and the bulb temperature is low, the mercury vapor pressure is low, and therefore the light emission amount is small, that is, at the time of starting. It has a problem that the luminous flux rising characteristics are not good.

As a measure against starting at such a low temperature, it has been proposed to use xenon or a mixed gas mainly containing xenon as a rare gas instead of argon or neon. Xenon gas starts discharge only with xenon itself and is not easily affected by temperature changes, so temperature characteristics are stable, and therefore reliable start-up is possible even when the ambient temperature is low, and the above-mentioned argon and neon are used. There is an advantage that the rising characteristics of the luminous flux are superior to those in the above case.

[0004]

By the way, such a mercury + xenon-encapsulated fluorescent lamp has hitherto been a fluorescent substance which emits visible light by being excited by ultraviolet rays of 185 nm and 254 nm emitted from mercury as a fluorescent substance, for example, Calcium halophosphate phosphors and three wavelength emission type phosphors have been used. This is because this type of mercury + xenon encapsulation type fluorescent lamp, when the bulb temperature rises after starting, promotes evaporation of the enclosed mercury and raises the mercury vapor pressure, which causes a large amount of UV emission by mercury. Become. When the lamp is in a stable lighting state, the amount of ultraviolet rays emitted from mercury is larger than the amount of ultraviolet rays emitted from xenon. Therefore, from the viewpoint of effectively utilizing the ultraviolet rays emitted from mercury when the lamp is in a stable lighting state, in the conventional case, a phosphor which is excited by ultraviolet rays of 185 nm and 254 nm emitted from mercury to emit visible light is used.

However, as described above, this type of mercury + xenon-encapsulated fluorescent lamp relies mainly on the emission of xenon when the vapor pressure of mercury is not sufficient at low temperature starting. However, the ultraviolet rays emitted from xenon gas mainly have wavelengths of 147 nm and 172 nm.
The ultraviolet rays in this wavelength range do not effectively excite the phosphor excited by the 185 nm and 254 nm ultraviolet rays emitted from the mercury.

As a result, the conventional mercury + xenon-filled type fluorescent lamp is superior in low-temperature startability to the conventional mercury + argon-filled type fluorescent lamp, but the luminous flux until stable lighting is insufficient. There was a problem that was.

The present invention has been made in view of the above circumstances. The object of the present invention is a mercury + xenon-encapsulated type fluorescent lamp, but the luminous flux until stable lighting can be further increased. An object of the present invention is to provide a fluorescent lamp having improved start-up characteristics, its lighting device, a light source device using the same, and a liquid crystal display device.

[0008]

The invention of claim 1 is mainly composed of a bulb; means for generating an electric discharge in the bulb; mercury and xenon enclosed in the bulb and emitting ultraviolet rays by the electric discharge. A rare gas; and a phosphor layer provided on the inner surface of the bulb, the phosphor layer having a phosphor that emits light by receiving ultraviolet rays emitted from the mercury and a phosphor that emits light by receiving ultraviolet rays of 200 nm or less. Is a fluorescent lamp.

Here, the means for generating electric discharge in the bulb may be a pair of cold cathodes sealed in the bulb, one internal cold cathode and one external electrode, or an external electrode. May be only. Further, it may be a hot cathode.

Further, the rare gas contains at least xenon, and xenon may be mixed with other rare gas such as neon. In short, xenon gas is sealed in the range of 30 to 100% as the rare gas. Good. Further, the lamp may have a straight tube shape, a ring shape, a U shape, a W shape, or another bent shape, or may have an aperture shape that emits light in a specific direction.

According to a second aspect of the invention, the phosphor layer has a phosphor that emits light by receiving ultraviolet rays emitted from mercury.
2. The fluorescent lamp according to claim 1, wherein the phosphor layer of 1) and a second phosphor layer having a phosphor that emits light upon receiving ultraviolet rays of 200 nm or less are laminated.

According to the third aspect of the present invention, the phosphor that emits light by receiving ultraviolet rays of 200 nm or less emits light mainly by receiving the ultraviolet rays of 147 nm and 172 nm emitted from xenon, and transmits the ultraviolet rays of around 250 nm, mainly 254 nm. It is a fluorescent substance, It is a fluorescent lamp of Claim 1 or Claim 2 characterized by the above-mentioned.

According to a fourth aspect of the present invention, the pressure for filling the rare gas is 20.
It is 0 Torr or less, It is a fluorescent lamp as described in any one of Claim 1 thru | or 3. Claim 5
The present invention is a fluorescent lamp lighting device, comprising: the fluorescent lamp according to any one of claims 1 to 4; and a lighting circuit for lighting the fluorescent lamp.

A sixth aspect of the present invention is a light source device comprising: the fluorescent lamp lighting device according to the fifth aspect; and a light source device body in which the fluorescent lamp lighting device is incorporated.

A seventh aspect of the present invention is a liquid crystal display device comprising: the light source device according to the sixth aspect; and a liquid crystal display panel which receives light emitted from the light source device on its back surface.

[0016]

According to the first aspect of the invention, as the phosphor, there are provided a phosphor that emits light by receiving ultraviolet rays emitted from mercury, and a phosphor that emits light by receiving ultraviolet rays of 200 nm or less. Therefore, when the engine is started at a low temperature, the xenon-excited phosphor emits visible light mainly due to the ultraviolet rays of 200 nm or less emitted from xenon, so that the luminous flux at the time of starting increases. Further, when the stable lighting state is reached, the evaporation of mercury becomes active and the mercury vapor pressure rises, so that the amount of ultraviolet rays emitted by mercury increases. In this case, the mercury-excited phosphor emits visible light, and the xenon-excited phosphor also emits visible light, which allows ultraviolet rays (254 nm) to pass therethrough without obstructing the penetration thereof, so that the light output during stable lighting is improved. . Therefore,
The luminous flux at the time of start-up increases, and compared with the conventional mercury + argon sealed type fluorescent lamp, the conventional mercury + xenon sealed type fluorescent lamp has improved rising characteristics of the luminous flux, and the luminous efficiency during stable lighting is also improved. improves.

According to the second aspect of the present invention, the phosphor layer has a first phosphor layer having a phosphor that emits light by receiving ultraviolet rays emitted from mercury, and fluorescent light that emits light by receiving ultraviolet rays of 200 nm or less. A laminated structure can be formed with the second phosphor layer having a body.

According to the third aspect of the present invention, the phosphor that emits light by receiving ultraviolet rays of 200 nm or less emits light mainly from 147 nm and 172 nm emitted from xenon and emits light by transmitting ultraviolet rays of 254 nm. because there is,
It efficiently receives ultraviolet rays and emits light, and the luminous flux at the time of cold start is increased.

According to the fourth aspect of the invention, since the total enclosed pressure of the rare gas is regulated to 200 Torr or less, the self-absorption of the rare gas is suppressed and the efficiency is reduced less. Moreover, even a thin valve is prevented from being damaged due to insufficient strength.

According to the inventions of claims 5 and 6,
It is possible to provide a fluorescent lamp lighting device and a light source device that are excellent in startability and luminous flux rising characteristics. According to the invention of claim 7, it is possible to provide a liquid crystal display device having excellent startability and rising characteristics of the luminous flux.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIGS. FIG. 1 shows the structure of a mercury + xenon sealed cold cathode fluorescent lamp and its lighting device. Reference numeral 1 is a mercury + xenon sealed cold cathode fluorescent lamp, 10 is a pulse voltage application device including a pulse inverter, and 11 Is a current limiting means.

The fluorescent lamp 1 has a long and narrow needle-shaped arc tube bulb 2, which has an inner diameter of 2.00 mm, for example.
Therefore, it has a cross-sectional area of 3.14 mm ² and is formed in a straight tube shape from lead glass having a length of 130 mm. A phosphor layer 3 is formed on the inner surface of the bulb 2. The phosphor layer 3 is
This embodiment has a two-layer laminated structure, and as shown in FIG. 1 (B), the inner surface of the bulb 2 is excited by ultraviolet rays having wavelengths of 185 nm and 254 nm emitted by mercury to emit visible light. First phosphor layer (mercury excitation type) 3a
And stacked on the discharge space side, ultraviolet rays of 200 nm or less, that is, wavelengths of 147 nm and 17 emitted by xenon.
It is composed of a second phosphor layer (Xe excitation type) 3b which emits visible light by ultraviolet rays of 2 nm.

The first phosphor layer 3a which emits visible light by the ultraviolet rays emitted by mercury is, for example, a calcium halophosphate phosphor 3Ca ₃ (PO ₄ ) ₂ .Ca (F, Cl) ₂ : S.
b, Mn, or a three-wavelength light emitting phosphor. The three-wavelength light-emitting phosphor may be, for example, Y ₂ O ₃ : Eu as a red phosphor and LaPO ₄ as a green phosphor.
Ce, Tb, BaMgAl ₁₄ O ₂₃ : E as a blue phosphor
u is used.

The second phosphor layer 3b, which emits visible light by ultraviolet rays of 200 nm or less, is made of, for example, Y ₃ (Al,
Ga) ₅ O ₁₈ ; Ce or Y ₂ SiO ₅ : Ce or BaAl ₁₂ O ₁₈ : Mn or Y ₃ Al ₅ O ₁₅ : Ce is used. These Y ₃ (Al, Ga) ₅ O ₁₈ ;
Ce phosphor, Y ₂ SiO ₅ : Ce phosphor and BaAl
_The emission intensity of each of the ₁₂ O ₁₈ : Mn phosphors with respect to the excitation wavelength is shown in FIG.
It is a phosphor that emits visible light when it receives ultraviolet rays of 0 nm or less, and has wavelengths of 147 nm and 172 emitted by xenon.
It is a phosphor that emits visible light by ultraviolet rays of nm.

A pair of cold cathodes 4 and 4 are sealed at both ends of the bulb 2 in the longitudinal direction. Each of the cold cathodes 4 and 4 is configured by joining a rod-shaped electrode body 6 to an electrode shaft 5 that also serves as a lead wire, and the electrode body 6 is formed of a nickel wire. The electrode shaft 5 is connected to a sealing wire 7 made of a metal having a coefficient of thermal expansion similar to that of glass, and the sealing wire 7 is sealed to a sealing portion 8 at the end of the bulb 2. The sealing wires 8 and 8 are connected to external lead wires 9 and 9, respectively.

The arc tube bulb 2 is filled with a predetermined amount of mercury and a predetermined pressure of xenon Xe or a rare gas mainly containing xenon. The total filling pressure of noble gas is 20
It is less than 0 Torr, and the partial pressure of xenon enclosed is more than 20 Torr. In the case of the present embodiment, a mixed gas in which neon Ne is mixed with xenon Xe is used, and for example, xenon Xe 60% and neon Ne 40%,
The total filling pressure is 50 Torr.

The cold cathode fluorescent lamp 1 having such a structure is
It is connected to a pulse voltage application device 10 such as the pulse inverter shown in FIG. 1 and a current limiting means 11.
The pulse voltage applying device 10 is adapted to apply a pulse having a rest period, that is, a pulse voltage having a predetermined duty ratio, between the cold cathodes 4 and 4. In this case, the pulse frequency is 30 to 80 kHz and the duty ratio τ is 2%.
As a result, it is 50% or less.

The current density of the cold cathode fluorescent lamp 1 of this type during stable lighting is regulated within the range of 0.75 mA / mm ² or less, and the sectional area of the bulb 2 is set to 20 mm ² or less. . The reason for restricting the current density to 0.75 mA / mm ² or less is that there is no point in increasing the current density by increasing the luminous efficiency to a saturated state even if the current density is increased beyond 0.75 mA / mm ^2. This is because the bulb 2 has a cross-sectional area of 20 mm ² or less because when the cross-sectional area exceeds 20 mm ² , self-absorption of xenon gas increases and luminous efficiency decreases. In the case of the above embodiment, the lamp current during stable lighting is 1.2 mA and the current density is 0.3.
It is 8 mA / mm ² . The operation of the cold cathode fluorescent lamp 1 having such a configuration will be described. When the lamp is on, xenon ionizes and excites to emit 147 nm and 172 nm UV radiation, and mercury vapor also ionizes and excites to emit 185 nm and 254 nm UV radiation.

By the way, when the ambient temperature is low, the evaporation of mercury is not sufficient, so that xenon is mainly ionized and excited to emit ultraviolet rays of 147 nm and 172 nm. This ultraviolet ray excites a phosphor that forms the second phosphor layer 3b and emits light by receiving an ultraviolet ray of 200 nm or less, and this phosphor emits visible light. The visible light is transmitted to the outside through the first phosphor layer 3a and the bulb 2.
Therefore, the luminous flux is increased and the rising of the luminous flux is accelerated as compared with the case where the second phosphor layer 3b is not provided.

FIG. 3 is a characteristic diagram showing the rising characteristics of the luminous flux at the time of low temperature starting, comparing the case of this embodiment with the case of the conventional case. In FIG. 3, characteristic a is for a conventional lamp in which a rare gas mixture of mercury, argon and neon is enclosed in the bulb (a phosphor layer is a three-wavelength emitting phosphor), and characteristic b is for mercury and xenon in the bulb. In the case of the conventional lamp in which the rare gas is filled (however, the phosphor layer is only the three-wavelength emitting phosphor), the characteristic c is in the case of the lamp of this embodiment in which the rare gas made of mercury and xenon is filled in the bulb (however, The phosphor layer is a laminated structure of the first phosphor layer 3a and the second phosphor layer 3b). The luminous flux rise at low temperature start is characteristic c
It can be seen that the case of the present invention shown by is most excellent.

When the bulb wall temperature rises and a stable lighting state is reached, the mercury vapor pressure rises, and the mercury vapor ionization and excitation increase. Then, ultraviolet rays of 185 nm and 254 nm are emitted from the mercury vapor, and when the ultraviolet rays pass through the second phosphor layer 3b, the phosphors of the second phosphor layer 3b are excited mainly by the ultraviolet rays of 185 nm to be visible. Emits light. Further, the 254 nm ultraviolet light passes through the second phosphor layer 3b and reaches the first phosphor layer 3a.
The three-wavelength light-emitting phosphor constituting a is excited. Therefore,
The first phosphor layer 3a also emits visible light. Therefore, visible light is emitted from both the first phosphor layer 3a and the second phosphor layer 3b during stable lighting.
These visible lights pass through the bulb 2 and are emitted to the outside.
Therefore, during stable lighting, compared to a conventional mercury + xenon enclosed type lamp with only one phosphor layer,
The luminous efficiency is improved, and the light output is increased as a whole.

Further, in the case of low power, the amount of ultraviolet rays emitted by mercury and the amount of ultraviolet rays emitted by xenon vary depending on the ambient temperature, as shown in FIG. However, since both of them emit at least ultraviolet rays, visible light is emitted from the first phosphor layer 3a and the second phosphor layer 3b, so that the luminous efficiency is improved and the light output is increased. .

By the way, the total filling pressure of xenon or a rare gas mainly containing xenon needs to be 200 Torr or less. When the total filling pressure of the rare gas is set to 200 Torr or more, the self-absorption of the rare gas is increased and the efficiency is lowered.
Since this type of lamp is a thin bulb, it is feared that it will be damaged due to insufficient strength. Therefore, the total filling pressure of the rare gas is
200 Torr or less is preferable.

Further, when the filling pressure of the entire rare gas is set to 200 Torr or less, the partial pressure of xenon may be selected according to the kind of the phosphor forming the second phosphor layer 3b. That is,
Xenon emits 147 nm and 172 nm UV radiation, whereas 147 nm UV radiation is predominantly atomic emission, whereas 172 nm UV emission is predominantly molecular emission. The enclosed gas pressure of xenon is, for example, 10 to 20.
When the Torr level is low, atomic emission occurs, and the ultraviolet radiation at 147 nm increases, and when the encapsulation pressure is higher than 20 Torr, molecular emission occurs and the ultraviolet emission at 172 nm increases.

As can be understood from FIG. 2, Y ₃ (Al, G
a) ₅ O ₁₈ ; Ce phosphor has a high efficiency of emitting visible light when excited by ultraviolet rays of 147 nm. Therefore, Y ₃ (Al, G
a) When ₅ O ₁₈ : Ce phosphor is used, the gas pressure of xenon may be lowered to about 10 to 20 Torr to increase the ultraviolet radiation of 147 nm. Further, the Y ₂ SiO ₅ : Ce phosphor and the BaAl ₁₂ O ₁₈ : Mn phosphor have high efficiency of being excited by ultraviolet rays of 172 nm to emit visible light.
These Y ₂ SiO ₅ : Ce phosphor and BaAl
_{When the 12} O ₁₈ : Mn phosphor is used, the pressure of the gas filled with xenon may be increased to 20 Torr or more to increase the ultraviolet radiation at 172 nm.

The mercury + xenon-filled type cold cathode fluorescent lamp 1 configured as described above can be used as a backlight of the liquid crystal display device shown in FIGS. 5 and 6, for example. In the liquid crystal display device shown in FIGS. 5 and 6, a backlight 21 is provided on the back surface of the liquid crystal display plate 20. The backlight 21 corresponds to the light source device of the present invention, and the backlight 21 is a light guide plate 2 made of translucent acrylic resin or the like.
2, the light guide plate 22 is surrounded by casings 23 on three sides except for the lower surface and one side surface. The casing 23 corresponds to the main body of the light source device, and the inner surface thereof forms the reflecting surface 24. On the open surface formed on one side of the casing 23, the cold cathode fluorescent lamp 1 of the mercury + xenon enclosure type as a light source is arranged.

The cold cathode fluorescent lamp 1 is housed in a cylindrical reflector 25 connected to face an open surface formed on one side of the casing 23. The inner surface of the cylindrical reflector 25 forms a reflecting surface 26, and the lamp 1 is housed in the reflector 25 with its lamp axis aligned with the center line of the reflector 25. The cylindrical reflector 25 is the case
A side wall facing the open surface formed on one side of the sing 23 is opened so that all the light emitted from the cold cathode fluorescent lamp 1 is introduced to one side surface of the light guide plate 22. .

The cold cathode fluorescent lamp 1 is adapted to be turned on by applying a pulse voltage from the pulse voltage applying device 10 shown in FIG. 1, and the light emitted from the lamp 1 is reflected by the reflector 25. The light is reflected by the inner reflection surface 26 and is introduced to one side surface of the light guide plate 22. The light introduced into the light guide plate 22 is reflected by the reflecting surface 24 formed on the inner surface of the casing 23.
The light is reflected by and is directed to the upper surface of the light guide plate 22. A light diffusing plate 27 is provided on the upper surface of the light guide plate 22, and the light directed to the upper surface of the light guide plate 22 is diffused by the light diffusing plate 27 so that the entire surface has substantially uniform brightness. Therefore, the liquid crystal display plate 20 arranged so as to face the light diffusing plate 27 is evenly illuminated from the back surface.

In such a liquid crystal display device, since the luminous flux rising characteristics at the time of starting the cold cathode fluorescent lamp 1 of mercury + xenon enclosure type are good, and the luminous efficiency during stable lighting is good, the liquid crystal display device is used as a liquid crystal display device. The start-up performance and the display performance during use are improved.

In the first embodiment, a phosphor that emits visible light by ultraviolet rays emitted by mercury, and a phosphor that emits visible light by ultraviolet rays of 200 nm or less, that is, ultraviolet rays of wavelengths 147 nm and 172 nm emitted by xenon. Are formed in different layers, and these first phosphor layers 3 are formed.
Although a and the second phosphor layer 3b have a laminated structure, the present invention is not limited to this, and the phosphor layer 3 having only one layer may be used as in the second embodiment shown in FIG. Good. However, this phosphor layer 3 emits visible light by a phosphor (first phosphor) that emits visible light by ultraviolet rays emitted by mercury and by ultraviolet rays of 200 nm or less, that is, ultraviolet rays of wavelengths 147 nm and 172 nm emitted by xenon. A phosphor (second phosphor) is mixed and used. Even in this case, the same effect as that of the first embodiment can be obtained.

Further, in the case of the first embodiment, the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type has been described in which the cold cathodes 4 and 4 are sealed inside both ends of the bulb 2, but the discharge is maintained. The means for doing so is not limited to this, and for example, the cold cathode 4 is sealed at one end of the bulb 2 and an external electrode is provided outside the bulb so that discharge is generated in the bulb between the cold cathode 4 inside and the external electrode. You may

Further, the fluorescent lamp 30 of the mercury + xenon enclosure type as in the third embodiment shown in FIG. 8 may be used. The fluorescent lamp 30 is provided with a pair of external electrodes 32, 32 facing each other and having a strip shape outside the bulb 31, and these external electrodes 32, 32 are connected to the pulse voltage applying device 10 and the current limiting means 11. As a result, electric discharge is generated in the bulb 31. Further, a phosphor coating 33 is formed on the inner surface of the bulb 31, and the phosphor coating 33 is excited by ultraviolet rays having wavelengths of 185 nm and 254 nm emitted by mercury to emit a visible light. Excitation type) 33a,
A second phosphor layer (Xe excitation type) 33b which emits visible light by ultraviolet rays having a wavelength of 200 nm or less, that is, ultraviolet rays having wavelengths of 147 nm and 172 nm emitted by xenon is laminated. Further, the valve 31 is filled with a predetermined amount of mercury and a predetermined pressure of xenon Xe or a rare gas mainly containing xenon in the range of the above-mentioned conditions.

Even with the external electrode type mercury + xenon encapsulation type fluorescent lamp 30 having such a structure, the luminous flux rising characteristics at the time of low temperature starting are excellent and the luminous efficiency is improved. Further, the present invention is not limited to the fluorescent lamp used as the backlight of the liquid crystal display device, but may be a small-diameter fluorescent lamp used as a pointer of a self-luminous type used in various meters, for example.

Further, the xenon gas may be mixed with another noble gas such as argon, neon or krypton. In short, xenon is mixed as the noble gas.
It may be enclosed in the range of 0 to 100%.

Furthermore, the invention can be implemented with an aperture type fluorescent lamp in which the emission intensity in a specific direction is increased.
Further, the present invention is not limited to the cold cathode fluorescent lamp and can be implemented with a hot cathode fluorescent lamp. An example applied to a hot cathode fluorescent lamp is shown in FIG. This example shows a case where the present invention is applied to a straight tube type fluorescent lamp 100 used as an exposure light source of a copying machine, and 101 is a straight tube type glass bulb and 10
Reference numeral 2 is a phosphor layer formed on the inner surface of the bulb 101.
The phosphor coating 102 is excited by ultraviolet rays having wavelengths of 185 nm and 254 nm emitted by mercury to emit visible light.
And a second phosphor layer (Xe excitation type) 102b which emits visible light by ultraviolet rays of 200 nm or less, that is, ultraviolet rays of wavelengths 147 nm and 172 nm emitted by xenon. It is configured.

Reference numeral 103 is a stem in which the end portion of the bulb 101 is closed, 104 is a lead wire, and 105 is a hot cathode. The stem 103 is provided with a thin tube 106 communicating with the discharge space, and the thin tube 106 houses an amalgam 107. As amalgam 107, 1 mercury Hg
A bismuth Bi-tin Sb-based alloy containing 5% by weight is used. Then, the valve 101 is filled with xenon or a rare gas mainly containing xenon within a range of 200 Torr or less.

When the fluorescent lamp 100 having such a structure is lit at an average current density of 3.9 mA / mm ² , the following operational effects are exhibited. That is, a straight tube type fluorescent lamp used as an exposure light source of a copying machine is required to have a large light output and a fast rise of a luminous flux. In order to increase the light output, it is necessary to flow a large current, but in this case, in the case of liquid mercury, the mercury vapor pressure rises too much and the efficiency drops. When the amalgam 107 is sealed in place of liquid mercury, the amalgam 107 has an action of adsorbing excess mercury vapor and controlling the mercury vapor pressure in the bulb 101. Therefore, when a large current is passed to increase the average current density, the light output is increased. Can be increased. However, since the amalgam 107 has an action of adsorbing saturated mercury vapor even when the ambient temperature is low, the mercury vapor pressure is low at the time of low temperature starting, and therefore, the rising characteristics of the luminous flux are inferior even when liquid mercury is used. There's a problem.

Therefore, in the fluorescent lamp shown in FIG. 8, xenon or a rare gas mainly composed of xenon is filled as the rare gas, and the fluorescent layer 102 has a wavelength 1 of mercury.
A first phosphor layer (mercury excitation type) 102a that emits visible light when excited by ultraviolet rays of 85 nm and 254 nm;
Ultraviolet rays of less than 00 nm, that is, the wavelength emitted by xenon 1
The second phosphor layer (Xe excitation type) 102b which emits visible light by ultraviolet rays of 47 nm and 172 nm constitutes a phosphor layer having a laminated structure.

In this way, xenon emits ultraviolet rays of 147 nm and 172 nm even when the mercury vapor pressure is low at the time of starting at low temperature, and these ultraviolet rays emit the ultraviolet rays of the second phosphor layer 10.
2b is excited to emit visible light. Therefore, the luminous flux at the time of low temperature start becomes large, and the luminous flux rising characteristic is improved. Further, during stable lighting, xenon and mercury simultaneously emit ultraviolet rays, and these ultraviolet rays emit the ultraviolet rays of the first phosphor layer 102a.
And the visible light is simultaneously emitted from the first phosphor layer 102b. Therefore, the light output is increased and the luminous efficiency is improved. Therefore, the light output is increased and the rising of the light flux is accelerated, which is effective when used as an exposure light source of a copying machine.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, and FIG. 1 (A) is a sectional view of a mercury + xenon sealed type cold cathode fluorescent lamp,
(B) figure is sectional drawing which follows the BB line of (A) figure.

FIG. 2 is a characteristic diagram showing the relationship between the excitation wavelength of each phosphor and its emission intensity.

FIG. 3 is a characteristic diagram showing luminous flux rising characteristics of a fluorescent lamp of the present invention and a conventional fluorescent lamp.

FIG. 4 is a characteristic diagram showing light output characteristics of mercury and xenon with respect to ambient temperature.

5 is an exploded perspective view of a liquid crystal display device using the cold cathode fluorescent lamp of FIG. 1 as a backlight.

FIG. 6 is a sectional view of the same liquid crystal display device.

FIG. 7 is a cross-sectional view of a mercury + xenon-filled type fluorescent lamp according to a second embodiment of the present invention.

FIG. 8 shows a third embodiment of the present invention, FIG. 8A is a sectional view of a cold cathode fluorescent lamp of a mercury + xenon enclosure type,
(B) figure is sectional drawing which follows the BB line of (A) figure.

FIG. 9 shows a fourth embodiment of the present invention, FIG. 9 (A) is a cross-sectional view of a mercury + xenon enclosed type hot cathode fluorescent lamp,
(B) figure is sectional drawing which follows the BB line of (A) figure.

[Explanation of symbols]

1 ... Mercury + xenon sealed type cold cathode fluorescent lamp 2 ... Bulb 3 ... Phosphor layer 3a ... First phosphor layer 3b ... Second phosphor layer 4 ... Cold cathode 10 ... Pulse voltage applying device 11 ... Current limitation Means 20 ... Liquid crystal display plate 21 ... Backlight 22 ... Light guide plate 25 ... Reflector 30, 100 ... Mercury + xenon sealed type fluorescent lamp 31, 101 ... Bulb 32 ... External electrode 104 ... Thermal electrode 33, 102 ... Phosphor layer 33a, 102a ... 1st fluorescent substance layer 33b, 102b ... 2nd fluorescent substance layer 107 ... Amalgam

Claims (7)

[Claims] 1. A valve; means for generating an electric discharge in the valve; a rare gas mainly containing mercury and xenon, which is enclosed in the valve and emits ultraviolet rays by the electric discharge; provided on an inner surface of the valve. And a phosphor layer having a phosphor that emits light by receiving the ultraviolet rays emitted from the mercury and a phosphor that emits light by receiving the ultraviolet rays having a wavelength of 200 nm or less, and a fluorescent lamp. 2. The phosphor layer includes a first phosphor layer having a phosphor that emits light when receiving ultraviolet rays emitted from mercury, and a second phosphor layer that has a phosphor emitting light when receiving ultraviolet rays of 200 nm or less. The fluorescent lamp according to claim 1, wherein the fluorescent material layers are stacked and formed. 3. A phosphor that emits light by receiving UV light of 200 nm or less is a phosphor that emits light mainly by receiving UV light of 147 nm and 172 nm emitted from xenon and transmits UV light at 254 nm. The fluorescent lamp according to claim 1 or 2. 4. The fluorescent lamp according to claim 1, wherein the filling pressure of the rare gas is 200 Torr or less. 5. A fluorescent lamp lighting device, comprising: the fluorescent lamp according to claim 1; and a lighting circuit for lighting the fluorescent lamp. 6. A light source device comprising: the fluorescent lamp lighting device according to claim 5; and a light source device body in which the fluorescent lamp lighting device is incorporated. 7. A liquid crystal display device, comprising: the light source device according to claim 6; and a liquid crystal display panel that receives light emitted from the light source device from a rear surface thereof.