JPH09199086A - Low-pressure mercury vapor discharge lamp and lighting device using the same - Google Patents

Abstract

(57) Abstract: To provide a low-pressure vapor discharge lamp which has a high emission intensity in the near infrared region and has a small amount of mercury adsorbed to improve the luminous flux maintenance rate, and an illumination device using the same. SOLUTION: Y activated with at least one of chromium and europium is formed on the inner surface of a translucent airtight container 1 in which a discharge is generated and mercury and a rare gas are sealed.
A low-pressure mercury vapor discharge lamp having a phosphor layer 20 having a AG structure and containing a phosphor having an emission peak wavelength in the near-infrared region. Since the near-infrared light emitting phosphor having the above YAG structure is used as the near-infrared light emitting phosphor, compared with the conventional iron-activated lithium aluminate phosphor,
The luminous intensity of near-infrared light is increased, and the adherence of mercury is small, so that the luminous flux maintenance factor is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure mercury vapor discharge lamp typified by a fluorescent lamp having an emission peak in the near infrared region and an illuminating device using the same.

[0002]

2. Description of the Related Art Fluorescent lamps having a light emission intensity in the near infrared region such as a wavelength of 650 nm to 800 nm are used as a light source for plant cultivation and a light source for OCR reading.
A conventional fluorescent lamp has an iron-activated lithium aluminate phosphor (Li) as disclosed in JP-A-52-89281 for increasing the emission intensity in the near infrared region.
AlO ₂ ; Fe) was used. Li AlO ₂ ; F
The e-phosphor has an emission peak wavelength at 740 nm and is effective in increasing the emission intensity in the near infrared region.

[0003]

However, the above-mentioned Li
Not only has it been found that the AlO ₂ ; Fe phosphor has a not so high emission intensity in the near infrared region, but it also has a problem that the luminous flux maintenance factor is not good because it has a property of easily binding to mercury. In particular, this type of Li AlO ₂ ; Fe phosphor has a strong effect of adsorbing mercury vapor in the discharge space.
The mercury adsorbed on the O ₂ ; Fe phosphor inhibits the UV phosphor from reaching the phosphor, reduces the visible light emission performance, and interferes with the transmission of visible light. Therefore, the luminous flux maintenance factor decreases as the lighting time elapses.

In particular, in compact fluorescent lamps and compact bulb fluorescent lamps, a thin glass tube having a tube diameter of about 10 mm to 17 mm is formed into a bent shape for high density, and a small and high luminous flux is emitted. The input power per unit length is higher than that of general fluorescent lamps. For this reason, the amount of mercury implanted per unit area of the phosphor increases, and the irradiation density of vacuum ultraviolet rays represented by 185 nm that affects the luminous flux maintenance factor of the phosphor increases. As a result, Li AlO
₂ ; Compact fluorescent lamps and compact fluorescent lamps that use Fe phosphors increase the amount of mercury adsorbed on Li AlO ₂ ; Fe phosphors, lower the luminous flux maintenance rate, and end the life of electrodes and circuit components. Therefore, there is a problem in that the long-life lamp, which is an advantage of the compact fluorescent lamp or the compact fluorescent lamp, cannot be used, such as the necessity of exchanging the lamp before it happens.

Further, in the case of a fluorescent lamp in which the mercury vapor pressure is high when the lamp is started and it takes several tens of minutes to several hours from the start to the stabilization of the characteristics, when the mercury vapor pressure is high. Since the amount of mercury injected per unit area of the phosphor increases, there is also a problem that deterioration of the phosphor, blackening of the glass, and reduction of the luminous flux maintenance factor due to adhesion of mercury to the phosphor tend to occur.

Therefore, the object of the present invention is to
It is an object of the present invention to provide a low-pressure vapor discharge lamp which has a high emission intensity in the near infrared region and has a small amount of mercury adsorbed to improve the luminous flux maintenance factor, and an illuminating device using the same.

[0007]

The low-pressure mercury vapor discharge lamp according to the invention of claim 1 is a low-pressure mercury vapor discharge lamp in which chromium and europium are formed on the inner surface of a transparent airtight container in which mercury and a rare gas are enclosed. A phosphor layer containing a phosphor having a YAG structure activated by at least one of the above and having an emission peak wavelength in the near infrared region.

Here, a phosphor having a YAG structure activated by at least one of chromium and europium and having an emission peak wavelength in the near infrared region means YAG.
A phosphor having a (yttrium alumina garnet) structure and an emission peak wavelength in the vicinity of 650 nm to 800 nm (hereinafter referred to as a near-infrared light emitting phosphor having a YAG structure), specifically, Y ₃ Al ₅ O ₁₂ ; Cr, Y ₃ Al
₅ O ₁₂ ; Eu, Y ₃ Al ₅ O ₁₂ ; Cr, Eu, Gd ₃ A
l ₅ O ₁₂ ; Cr, Y ₃ Ga ₅ O ₁₂ ; Cr, Gd ₃ Ga ₅
O ₁₂ ; Cr, Y ₃ Al ₂ Ga ₃ O ₁₂ ; Cr, Y ₃ AlG
a ₄ O ₁₂ ; Cr or the like is used.

For the phosphor layer, the near-infrared light emitting phosphor having the YAG structure may be used alone or in combination with another phosphor. The low-pressure mercury vapor discharge lamp is typified by a fluorescent lamp, but the means for generating an electric discharge inside may be sealed inside the translucent airtight container or provided outside. The electrode may be a hot cathode or a cold cathode. The transparent airtight container is usually formed of a glass tube. Noble gas is enclosed in this glass tube in addition to mercury.

The present inventors have found that the emission peak wavelength is 650 nm.
As a result of various investigations on phosphors in the vicinity of ~ 800 nm, the near-infrared light-emitting phosphor having the above YAG structure shows near-infrared light emission as compared with the conventional iron-activated lithium aluminate phosphor (Li AlO ₂ ; Fe). It has been found that not only the emission intensity is high, but also the adhesion of mercury is small and the luminous flux maintenance factor is excellent. Therefore, the lamp in which the near-infrared light-emitting phosphor having the YAG structure is applied to the inner surface of the glass tube to form the phosphor coating has a higher near-infrared emission intensity than the conventional lamp and is excellent in the luminous flux maintenance factor. Become a lamp.

According to a second aspect of the present invention, in the low-pressure mercury vapor discharge lamp according to the first aspect, the phosphor having a YAG structure and an emission peak wavelength in the near infrared region is a chromium-activated yttrium aluminate phosphor ( Y ₃ Al ₅ O ₁₂ ; Cr) is the main component.

Among the near-infrared light emitting phosphors having the YAG structure, the chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) has a particularly high near-infrared light emission intensity and an excellent luminous flux maintenance factor. ing.

According to a third aspect of the present invention, in the low-pressure mercury vapor discharge lamp according to the first or second aspect, a phosphor having the above YAG structure and having an emission peak wavelength in the near infrared region is used as the phosphor layer. And a fluorescent substance having a peak wavelength in the visible light region.

According to the low-pressure mercury vapor discharge lamp of claim 3,
When the lamp is turned on, not only light in the near-infrared region but also visible light can be obtained at the same time, so it can be used as a light source for lighting, and can be used in a wide range of fields including other light sources for plant cultivation. .

According to a fourth aspect of the present invention, in the low-pressure mercury vapor discharge lamp according to any one of the first to third aspects, the phosphor having an emission peak wavelength in the visible light region is a three-wavelength band emission type phosphor. It is characterized by being.

The three-wavelength band emission type phosphor is a mixture of three kinds of phosphors having peak wavelengths in red, blue and green wavelength bands. For example, a red phosphor has trivalent europium. Yttrium oxide phosphor Y ₂ O ₃ : Eu ³⁺ , a blue phosphor is a divalent europium-activated alkaline earth halophosphate phosphor (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl
₂ : Eu ²⁺ or divalent europium activated alkaline earth aluminate phosphor BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , and terbium Tb activated silica / phosphoric acid containing cerium Ce as a green phosphor Salt phosphor (La, Ce, T
b). (P, Si) O ₄ or the like can be used,
It may be combined with other phosphors as long as it is a three-wavelength band emission type.

If the phosphor that emits visible light is a phosphor of three-wavelength band emission type, in addition to light emission in the near infrared region, red, green,
Since light emission in the blue visible region is obtained, the luminous efficiency is improved and the applicable range is further widened.

According to a fifth aspect of the present invention, in the low-pressure mercury vapor discharge lamp according to any one of the first to fourth aspects, the phosphor layer has the YAG structure and emits light in order from the wall surface side of the hermetic container. It is characterized by being formed by a layer mainly composed of a phosphor having a peak wavelength in the near infrared region and a layer mainly composed of the visible light emitting phosphor.

Usually, when a near-infrared light emitting phosphor having a YAG structure and a visible light emitting phosphor are used in combination, it is often required to increase the emission intensity of visible light. According to the low-pressure mercury vapor discharge lamp of claim 5, the ultraviolet light emitted from the mercury in the discharge space excites the visible light emitting phosphor located on the discharge space side to emit visible light, and the visible light emitting phosphor is emitted. The ultraviolet light that has passed through excites the near-infrared light emitting phosphor having a YAG structure to emit near-infrared light. Since a large proportion of ultraviolet rays irradiate the visible light emitting phosphor located on the discharge space side, the amount of visible light emitted is larger than that in the case where the laminated structure is reversed.

According to a sixth aspect of the invention, in the low-pressure mercury vapor discharge lamp according to any one of the first to fifth aspects, a protective layer made of a metal oxide is provided between the inner surface of the hermetic container and the phosphor layer. It is characterized by that.

Generally, in the case of a lamp having a large input power per unit length or a lamp which is lit in an atmosphere having a high ambient temperature, mercury is penetrated through the phosphor layer from the discharge space side, and ultraviolet rays are emitted. Irradiate the glass after passing through the phosphor layer, and as a result, an alkaline component is deposited from the glass and reacts with the phosphor to cause a phenomenon such as deterioration of the brightness of the phosphor, blackening of the glass, and increased consumption of mercury. This leads to a decrease in the maintenance rate. On the other hand, according to the low-pressure mercury vapor discharge lamp of claim 6, since the protective layer made of metal oxide is provided between the inner surface of the airtight container and the phosphor layer, this protective film transmits the phosphor layer. It prevents the mercury from being injected and also prevents the ultraviolet rays that have passed through the phosphor layer from reaching the glass, preventing the alkaline components from precipitating from the glass, thus deteriorating the phosphor, blackening the glass, and mercury. The consumption of can be suppressed. As a result, the luminous flux maintenance factor can be increased.

According to a seventh aspect of the invention, in the low pressure mercury vapor discharge lamp according to the sixth aspect, the protective layer is Al ₂ O ₃ or TiO _2.
It is characterized by comprising at least one of ₂ , ₂ , SiO ₂ , ZnO, CeO ₂ , and Y ₂ O ₃ .

Al ₂ O ₃ , TiO ₂ , SiO ₂ , Zn
Metal oxides such as O, CeO ₂ , and Y ₂ O ₃ have an excellent effect of blocking transmission of mercury and ultraviolet rays and transmitting visible light, and are therefore suitable as a protective film.

The invention of claim 8 is the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 7, characterized in that an amalgam is contained in the hermetic container as a mercury vapor pressure control means.

A low-pressure mercury vapor discharge lamp using an amalgam as a mercury vapor pressure control means has an effect that the amalgam regulates the mercury vapor pressure in the discharge space to an optimum pressure when stable lighting is achieved. Can occur for several tens of minutes to several hours. If the state of high mercury vapor pressure continues for a long time as described above, the implantation of mercury ions into the phosphor or glass increases, and deterioration of the phosphor or coloring (blackening) of the glass tends to proceed early. As a phosphor used in such a situation, a conventional iron-activated lithium aluminate phosphor (Li
When AlO ₂ ; Fe) is used, mercury is easily adsorbed, so that the phosphor is deteriorated and the luminous flux maintenance factor is greatly reduced. On the other hand, a near-infrared light emitting phosphor having a YAG structure is less likely to adsorb mercury as compared with the above Li AlO ₂ ; Fe phosphor, so that the phosphor is less deteriorated and the luminous flux maintenance ratio is excellent. Become.

A low-pressure mercury vapor discharge lamp according to the invention of claim 9 is
The low-pressure mercury vapor discharge lamp according to any one of claims 1 to 8 and a lighting circuit are integrated, and a bulb-type fluorescent lamp is configured with a base connected to the lighting circuit. It is characterized by being

In this case, the lighting circuit includes an electronic ballast and a choke coil ballast, and may be a high frequency lighting type. The airtight container of the low-pressure mercury vapor discharge lamp may have a structure covered with a globe or a structure exposed to the outside.

The bulb-type fluorescent lamp has a bent glass tube so as to have a high density, and is designed to emit a high luminous flux in a small size. The input power per unit length is higher than that of a general fluorescent lamp. Therefore, the amount of mercury injected per unit area of the phosphor increases. As a result, the conventional Li AlO
₂ ; In the bulb-type fluorescent lamp using the Fe phosphor, the luminous flux maintenance rate decreases due to an increase in the amount of mercury deposited, and the electrodes and circuit components must be replaced before they reach the end of their service lives. On the other hand, when the near-infrared light emitting phosphor having the YAG structure is used, the amount of attached mercury is small and the luminous flux maintenance factor is improved.

An illumination device according to a tenth aspect of the invention is the illumination device according to the first aspect.
The low-pressure mercury vapor discharge lamp according to claim 9 is used as a light source. According to the invention of claim 10, it is possible to provide an OA device that makes use of the advantages of the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 9.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to a first embodiment shown in FIGS. FIG. 1 is a diagram showing the structure of a bulb-type fluorescent lamp, FIG. 2 is a configuration diagram of a phosphor coating formed on the inner surface of an arc tube, and FIG. 3 is a chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr)
FIG. 4 is a characteristic diagram showing the emission spectrum, FIG. 4 is a characteristic diagram showing the spectral energy distribution showing the emission intensity of the chromium-activated yttrium aluminate phosphor and the conventional iron-activated lithium aluminate phosphor, and FIG. 5 is the luminous flux maintenance factor. FIG. 6 is a diagram showing the amount of mercury consumed in the arc tube, and FIG. 7 is a characteristic diagram showing changes in the mercury vapor pressure in the tube at the time of starting.

In FIG. 1, reference numeral 1 is an arc tube corresponding to a translucent airtight container, which is formed by bending a straight glass tube having an outer diameter of 12 mm into a saddle shape. The end of the arc tube 1 is hermetically sealed by a stem 2, and an electrode 3 composed of a hot cathode is attached to the stem 2. The electrode 3 is formed of a tungsten coil filament and is supported by a pair of lead wires 4 and 4 which penetrate through the stem 2 and are guided. The electrodes 3 include BaO, SrO, and Ca (not shown).
An electron emissive material (emitter) such as O is applied.

A thin tube 5 is projected from the stem 2 and the thin tube 5 communicates with the discharge space. A main amalgam 6 made of mercury, bismuth Bi, indium In, etc. is accommodated in the thin tube 5, and an auxiliary amalgam 7 made of mercury, indium In, etc. is provided at a position close to the electrode 3 on the one lead wire 4. Is installed.

A phosphor layer is formed on the inner surface of the arc tube 1 as shown in FIG. This phosphor will be described later. The arc tube 1 is filled with a rare gas containing argon or the like at a predetermined pressure, for example, about 3 Torr.

The arc tube 1 has a partition plate 10 via an adhesive 11.
It is fixed to. The partition plate 10 is attached to one end of a synthetic resin cover 12. One end of the cover 12 is closed by the partition plate 10, and a screw-type base 13 such as E26 is attached to the other end. And
A high-frequency lighting electronic circuit device 15 mounted on a wiring board 14 is accommodated in the cover 12. The arc tube 1
Is electrically connected to this high frequency lighting type electronic lighting circuit device 15, and this high frequency lighting type electronic lighting circuit device 15 is electrically connected to the screw type base 13. Therefore, the arc tube 1 is lit at high frequency. The arc tube 1 is covered with a translucent globe 16 fixed to the partition plate 10.

The phosphor layer formed on the inner surface of the arc tube 1 will be described with reference to FIG. A phosphor layer 20 is formed on the inner surface of the glass tube 1 that constitutes the arc tube. The phosphor layer 20 has at least a near-infrared light emitting phosphor having a YAG structure. The near-infrared emitting phosphor having a YAG structure means, as described above, Y activated by at least one of chromium and europium.
Has an AG structure and has an emission peak wavelength of 650 nm to 80
It refers to a phosphor in the near infrared region of 0 nm, and specifically, Y ₃ Al ₅ O ₁₂ ; Cr, Y ₃ Al ₅ O ₁₂ ; Eu,
Y ₃ Al ₅ O ₁₂ ; Cr, Eu, Gd ₃ Al ₅ O ₁₂ ; C
r, Y ₃ Ga ₅ O ₁₂ ; Cr, Gd ₃ Ga ₅ O ₁₂ ; Cr,
_{Y 3 Al 2 Ga 3 O 12} ; Cr, Y 3 AlGa 4 O 12; C
At least one kind such as r is used.

In the case of this embodiment, a chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) which has a high near-infrared emission intensity and an excellent luminous flux maintenance factor is used. Such a chromium-activated yttrium aluminate phosphor may be used alone, but is also used in combination with a visible light emitting phosphor that emits visible light. The visible light emitting phosphor is a calcium halophosphate phosphor {3Ca ₃ (PO ₄ ).
₂ · CaX ₂ ; Sb, Mn (X is F, Cl)} may be used, but in this example, a three-wavelength band emission type rare earth phosphor is used. The three-wavelength emission type rare earth phosphor is, for example, trivalent europium-activated yttrium oxide phosphor Y ₂ O ₃ : Eu ^{3+ for} a red phosphor, and divalent europium-activated alkaline earth for a blue phosphor. Halophosphate phosphors (Sr, C
a, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ or divalent europium-activated alkaline earth aluminate phosphor Ba
Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ and terbium Tb-activated silicate / phosphate phosphor (La, Ce, Tb) / (P, Si) O ₄ etc. containing cerium Ce as the green phosphor. It is used.

When the chromium-activated yttrium aluminate phosphor and the visible light emitting phosphor are used in combination, they may be mixed to form a single-layer coating, but separate coatings are formed and laminated. It is better to have a structure.

The phosphor layer 20 shown in FIG. 2 is formed by laminating a layer 21 composed of a chromium-activated yttrium aluminate phosphor and a layer 22 of a visible light phosphor composed of a three-wavelength band emission type rare earth phosphor. There is. In this case, the chromium-activated yttrium aluminate phosphor layer 21 is provided on the glass tube 1 side, and
Visible Light Phosphor Layer 22 Made of Rare Earth Phosphor
Is provided on the discharge space side. The chromium-activated yttrium aluminate phosphor and the three-wavelength-emitting rare earth phosphor may be powder having an average particle size of 1.0 μm or less and 0.1 μm or more, and the chromium-activated yttrium aluminate phosphor layer 21. be in a film thickness t _1, and 3 the thickness t ₂ of the visible light phosphor layer 22 made of band fluorescent type rare-earth phosphor is equivalent film thickness, respectively, of these thickness t ₁ and t ₂ 1
The range of 0 μm to 30 μm is preferable.

By setting the film thickness t ₁ of the chromium-activated yttrium aluminate phosphor layer 21 to 10 μm to 30 μm, the amount of near infrared light emission can be increased. Film thickness is 10 μm
When it is less than the above value, the near infrared ray emission amount decreases, and when the film thickness exceeds 30 μm, the near infrared ray emission amount also decreases due to self-absorption of the phosphor layer.

Further, the film thickness t _{2 of the} visible light phosphor layer 22 made of the three-wavelength band emission type rare earth phosphor is also 10 μm to 30 μm.
If so, the amount of visible light emitted can be increased. When the film thickness is less than 10 μm, the amount of visible light emitted decreases, and when the film thickness exceeds 30 μm, the amount of visible light also decreases due to self-absorption of the phosphor layer.

Further, a protective layer 30 made of metal oxide is formed between the phosphor layer 20 and the glass tube 1. This protective layer 30 is made of Al ₂ O ₃ , TiO ₂ , Si.
It is composed of at least one of O ₂ , ZnO, CeO ₂ , and Y ₂ O ₃ , and has a film thickness t ₃ of 0.1 μm to 5 μm.
The range of m is good.

The operation of the self-ballasted fluorescent lamp having such a structure will be described. Input power 15W, lamp current 2
When this lamp is turned on at 00 mA (tube wall load 110 mW / cm ² ), ultraviolet rays emitted from mercury are emitted from the phosphor layer 20.
The phosphor layer 20 emits visible light and near infrared rays. That is, the phosphor layer 20 is formed by laminating a layer 22 of a visible light phosphor made of a three-wavelength band emission type rare earth phosphor and a layer 21 made of a chromium-activated yttrium aluminate phosphor, so that 3 The wavelength range emitting rare earth phosphor emits visible light, and the chromium-activated yttrium aluminate phosphor emits near infrared light having an emission peak at 720 nm. For this reason, in addition to visible light with three-wavelength light emitted for ordinary lighting, near-infrared light near 720 nm emits enhanced light. As a result, light sources for plant cultivation and OC
It is effective when used as a light source for R reading.

In particular, since the present embodiment is a light bulb type fluorescent lamp, it can be used as a light source for plant cultivation by attaching it to a screw-type socket of an existing plant cultivation facility together with other light sources. In addition, a large power saving effect can be obtained by replacing it with an incandescent light bulb.

The chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) has a shape of the emission spectrum depending on the concentration of Cr, that is, a peak wavelength or a tail to the long wavelength side or the short wavelength side. However, one example is shown in FIG. That is, in this case, it has an emission peak at 720 nm.

The chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) is shown in FIG. 4 when compared with the conventional iron-activated lithium aluminate phosphor (Li AlO ₂ ; Fe). As shown, the emission intensity of near infrared rays is about 2.5 times as strong. FIG. 4 shows the spectral energy distribution characteristics when only the near-infrared phosphor layer is formed on the inner surface of the arc tube without using the visible light phosphor, and the light emission of 600 nm or less is the emission spectrum of mercury. is there. As can be seen from FIG. 4, the conventional iron-activated lithium aluminate phosphor (Li AlO ₂ ; Fe) has an emission peak wavelength at approximately 740 nm, but has a low relative emission energy. (Y ₃
Al ₅ O ₁₂ ; Cr) has an emission peak at 720 nm,
The relative emission energy is about 2.5 times that of Li AlO ₂ ; Fe.

From this fact, chromium activated yttrium aluminate phosphor (Y ₃ Al
_The near infrared light emission intensity is higher when ₅ O ₁₂ ; Cr) is used.

FIG. 5 is a characteristic diagram of the luminous flux maintenance factor of the bulb-type fluorescent lamp shown in FIG. 1. The solid line shows the chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O _5).
12 ; Cr), the broken line shows the case of using a conventional iron-activated lithium aluminate phosphor (Li AlO ₂ ; Fe). From this figure, a chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅
It can be seen that the luminous flux maintenance factor is much better when O ₁₂ ; Cr) is used.

The reason for this is that the chromium-activated yttrium aluminate phosphor has a small effect of adhering mercury to the phosphor, and thus has a small effect of blocking ultraviolet rays and visible light. The amount of mercury consumed is clear from the experimental results shown in FIG.

From the above, the bulb-type fluorescent lamp of this embodiment has a high near-infrared emission intensity and an improved luminous flux maintenance factor. In the case of the bulb-type fluorescent lamp as described above,
Lighting is performed with a relatively high tube wall load, and the arc tube temperature also rises. For this reason, the mercury vapor pressure also becomes relatively high, and there is a concern that the implantation of mercury from the discharge space toward the tube wall will become violent.

On the other hand, in the present example, the chromium-activated yttrium aluminate phosphor (Y
_{Since 3} Al ₅ O ₁₂ ; Cr) is used, the ratio of mercury adhering to the near-infrared light emitting phosphor is small, and thus the near-infrared light emitting phosphor is less likely to deteriorate. Moreover, since the protective layer 30 made of a metal oxide is provided between the inner surface of the arc tube 1 and the layer 21 made of the chromium-activated yttrium aluminate phosphor, this protective film 30 is used as the fluorescent layers 22 and 2.
Mercury that has passed through 1 is prevented from being implanted into the glass, and ultraviolet rays that have passed through the phosphor layers 22 and 21 are prevented from reaching the glass. Therefore, the consumption of mercury is suppressed, the alkali component is prevented from precipitating from the glass,
Therefore, deterioration of the phosphor and blackening of the glass due to the alkaline component can be prevented. Also from this, the luminous flux maintenance factor can be increased.

The protective layer 30 is made of Al ₂ O ₃ , TiO _2.
2 , SiO ₂ , ZnO, CeO ₂ , and Y ₂ O ₃ and at least one of these oxides is excellent in the transmission of visible light and excellent in the action of blocking the transmission of mercury and ultraviolet rays, and therefore is protected. Suitable as a film.

Furthermore, since the bulb-type fluorescent lamp is lit in a state where the tube wall load is high and the arc tube temperature rises,
Amalgams 6 and 7 are used to maintain the mercury vapor pressure in the tube at an optimum level. In this case, in order to improve the starting ability of the lamp, the auxiliary amalgam 7 is used in the vicinity of the electrode 3, but in this case, a large amount of mercury is released from the auxiliary amalgam 7 immediately after starting. Therefore, the mercury vapor pressure in the tube becomes high as shown in FIG. As the lighting time elapses, the mercury vapor will be aggregated in the main amalgam 6 installed in the low temperature portion, and the excess mercury will be captured by the main amalgam 6. As described above, it may take several tens of minutes to several hours from the start to stabilize the mercury vapor pressure. In a fluorescent lamp having such operating characteristics, the mercury vapor pressure is high until the mercury vapor pressure stabilizes from the start. The situation continues, and at this time, there is a concern that the implantation of mercury from the discharge space toward the tube wall will also become violent.

However, in the present embodiment, chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) is used as the near-infrared light emitting phosphor, so that mercury is attached to the near-infrared light emitting phosphor. Therefore, the rate of deterioration of the near-infrared light emitting phosphor is reduced. Also,
A protective layer 3 made of a metal oxide is provided between the inner surface of the arc tube 1 and a layer 21 made of a chromium-activated yttrium aluminate phosphor.
Since 0 is provided, this protective film 30 blocks the implantation of mercury that has passed through the phosphor layers 22 and 21 into the glass, and prevents the ultraviolet rays that have passed through the phosphor layers 22 and 21 from reaching the glass. To do. Therefore, the consumption of mercury can be suppressed, and the alkaline component can be prevented from precipitating from the glass, thereby preventing the deterioration of the phosphor and the blackening of the glass. Also from this, the luminous flux maintenance factor can be increased.

In the above embodiment, the case of the bulb-type fluorescent lamp in which the arc tube 1 is covered with the globe 16 has been described, but the present invention is not limited to this, and as in the second embodiment shown in FIG. The present invention can be implemented even with a bulb-type fluorescent lamp having a structure in which the arc tube 1 is exposed to the outside. In this case, the arc tube 1 is formed by joining two U-shaped glass tubes at their ends to form one continuous discharge space. Also,
In the drawing of FIG. 8, the same members as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted.

The present invention may be applied to a straight tube fluorescent lamp. FIG. 9 shows a hot cathode type straight tube fluorescent lamp according to a third embodiment of the present invention.
Is the end of the arc tube 51 made of glass and the stem 52, 5
2, and the electrodes 52, 54 of the hot cathode made of a tungsten filament are attached to these stems 52, 52 via internal lead wires 53. The electrodes 54, 54 are coated with an electron emitting substance (emitter) made of BaO, SrO, CaO or the like, which is not shown.

Bases 55, 55 are attached to the ends of the arc tube 51, and base pins 56 ... Connected to the internal lead wires 53. A protective film 57 made of a metal oxide is formed on the inner surface of the arc tube 51, a near-infrared light emitting phosphor layer 58 is formed inside the protective film 57, and a visible light emitting phosphor layer is further formed inside the protective film 57. 59 are laminated.

The protective layer 57 is made of Al as in the previous embodiment.
₂ O ₃ , TiO ₂ , SiO ₂ , ZnO, CeO ₂ , Y ₂
It is composed of at least one of O ₃ . The near-infrared light emitting phosphor layer 58 is formed of chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr), and the visible light emitting phosphor layer 59 is a three-wavelength region emitting type. It is made of a phosphor. The arc tube 51 is filled with a predetermined amount of mercury and a rare gas such as argon.

Even with a fluorescent lamp having such a structure,
Since the chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr) is used as the near-infrared light emitting phosphor, the near-infrared light emission intensity is high, and the mercury deposition rate is small, so the mercury is consumed. And the luminous flux maintenance factor can be increased.

The straight tube fluorescent lamp 50 can also be used as a light source for OA equipment, and can be applied to, for example, a device for reading an image, a character or a bar code shown.
That is, FIG. 10 shows an image reading apparatus, and in FIG.
Is a fluorescent lamp having the structure shown in FIG. 9, and 61 is a reflector. The reflector 61 is formed by pressing an aluminum plate, for example, and its cross section has a partial elliptical shape, that is, approximately a U shape, and has a long shape along the bulb axis of the fluorescent lamp 50. The whole is almost gutter-shaped. The fluorescent lamp 50 is arranged substantially at the focal position of the reflector 61, and the light emitted from the lamp 50 is reflected by the reflector 61 and is condensed at a fixed position on the original placing glass plate 62. There is. A read original 63 is placed on the original placing glass plate 62, and the lower surface of the original 63 is illuminated by the above-mentioned light collection. Then, the reflected light is imaged on the photoelectric conversion element 65 through the optical imaging lens system 64 provided in the lower part. Therefore,
An image written on the original 63 is read by the photoelectric conversion element 65 via the optical imaging lens system 64 by the light emitted from the fluorescent lamp 50.

The fluorescent lamp 50, the reflector 61, the optical imaging lens system 64 and the photoelectric conversion element 65 are arranged in the frame 6
6, the integrated unit moves horizontally relative to the original placing glass plate 62, so that the image of the read original 63 is scanned. The fluorescent lamp is not limited to the hot cathode, but can be applied to a cold cathode fluorescent lamp.

In each of the embodiments described above, the structure in which the protective film is formed on the inner surface of the arc tube, the phosphor layer for near infrared light emission inside the protective film, and the visible light emitting phosphor layer inside the phosphor film is laminated. The protective layer is not always necessary. Further, the phosphor layer is not limited to the structure in which the near-infrared light emitting phosphor layer and the visible light emitting phosphor layer are stacked on the discharge space side, and as shown in FIG. A three-wavelength light-emitting phosphor layer 22 is provided on the inner surface, and a chromium-activated yttrium aluminate phosphor (Y ₃
A near-infrared light emitting phosphor layer 21 made of Al ₅ O ₁₂ ; Cr) or the like may be provided. However, for a lamp that wants to emit a large amount of visible light, a chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ;
A near-infrared emitting phosphor layer 21 made of Cr) or the like,
Inside this (the discharge space side), the three-wavelength band emission type phosphor layer 22 is provided.
Should be provided.

Further, as shown in FIG. 11B, the phosphor layer is composed of a three-wavelength band emission type phosphor and a chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅ O ₁₂ ; Cr). A single layer may be formed by mixing with a phosphor for emitting near infrared rays.

Furthermore, the phosphor layer is formed as shown in FIG.
As shown in the figure, the chromium-activated yttrium aluminate phosphor (Y ₃ Al ₅
It may be formed only by a near-infrared light emitting phosphor such as O ₁₂ ; Cr), and the spectral energy distribution in this case is shown in FIG.

The near-infrared light emitting phosphor of the present invention is a chromium-activated yttrium aluminate phosphor (Y ₃
Not only Al ₅ O ₁₂ ; Cr) but Y as described above
It has an AG (yttrium alumina garnet) structure,
Any phosphor having an emission peak wavelength in the vicinity of 650 nm to 800 nm may be used, and other phosphors may be Y ₃ Al ₅
O ₁₂ ; Eu, Y ₃ Al ₅ O ₁₂ ; Cr, Eu, Gd ₃ Al
₅ O ₁₂ ; Cr, Y ₃ Ga ₅ O ₁₂ ; Cr, Gd ₃ Ga ₅ O
₁₂ ; Cr, Y ₃ Al ₂ Ga ₃ O ₁₂ ; Cr, Y ₃ AlGa ₄
O _12; at least one may be used, such as Cr.

FIG. 12 shows the emission spectrum of the Y ₃ Al ₅ O ₁₂ ; Eu phosphor, and FIG. 13 shows the emission spectrum of Y ₃ Ga ₅ O ₁₂ ; C.
The emission spectrum of the r phosphor is shown in FIG.
d ₃ Al ₅ O ₁₂ ; Cr showing the emission spectrum of the phosphor,
Furthermore, FIG. 15 shows the emission spectrum of the Gd ₃ Ga ₅ O ₁₂ ; Cr phosphor. In the emission spectra of these phosphors, the peak wavelength slightly shifts toward the long wavelength side or the short wavelength side depending on the concentration of the activator, or the skirt of the peak waveform narrows or widens, but a typical example is shown here. It can be seen that each of these phosphors has a YAG structure and has an emission peak wavelength in the vicinity of 650 nm to 800 nm.

[0066]

As described above, according to the invention of claim 1, the near infrared light emitting phosphor has an emission peak wavelength of 650.
Since a phosphor having a YAG structure in the vicinity of nm to 800 nm was used, the conventional iron-activated lithium aluminate phosphor (L
Compared with the case of using iAlO ₂ ; Fe), the emission intensity of near-infrared rays becomes higher, and the adherence of mercury is less, so that the luminous flux maintenance factor is improved.

According to the invention of claim 2, as a phosphor having a YAG structure activated by at least one of chromium and europium and having an emission peak wavelength in the near infrared region, a chromium-activated yttrium aluminate phosphor. (Y ₃ A
Since l ₅ O ₁₂ ; Cr) is used, the emission intensity of near-infrared rays is particularly high, and the luminous flux maintenance factor is excellent.

According to the third aspect of the present invention, since the near-infrared light emitting phosphor having the YAG structure and the phosphor having an emission peak wavelength in the visible light region are used together as the phosphor layer, It becomes possible to obtain visible light emission at the same time as light emission, and it is possible to use in a wide range of fields such as a light source for illumination and other light sources for plant cultivation.

According to the invention of claim 4, since the three-wavelength band emission type phosphor is used as the phosphor whose emission peak wavelength is in the visible light region, in addition to light emission in the near infrared region, red, green,
Light emission in the blue visible region can be obtained, thus improving the luminous efficiency and further increasing the range of application of the lamp.

According to the invention of claim 5, the layer of the near-infrared light emitting phosphor having the YAG structure and the layer of the visible light emitting phosphor are formed in order from the wall surface side of the airtight container. The amount of visible light emitted is greater than in the opposite case.

According to the invention of claim 6, since a protective layer made of a metal oxide is provided between the inner surface of the airtight container and the phosphor coating, for example, a lamp having a large input power per unit length or a surrounding area. In the case of a lamp that is turned on in a high temperature atmosphere, the protective film prevents implantation of mercury that has passed through the phosphor layer, and prevents ultraviolet rays that have passed through the phosphor layer from reaching the glass. Therefore, it is possible to prevent the alkaline component from being deposited, thereby suppressing deterioration of the phosphor, blackening of the glass, and consumption of mercury. As a result, the luminous flux maintenance factor can be increased.

According to the invention of claim 7, the protective layer is made of Al ₂
O ₃ , TiO ₂ , SiO ₂ , ZnO, CeO ₂ , Y ₂ O
_Since it is composed of at least one of the _three metal oxides, it has an excellent effect of blocking transmission of mercury and ultraviolet rays and transmitting visible light.

According to the eighth aspect of the present invention, even in a lamp containing amalgam as a mercury vapor pressure control means in an airtight container, since the near-infrared light emitting phosphor having the YAG structure is used, deterioration of the phosphor is small. , The luminous flux maintenance factor becomes excellent.

According to the invention of claim 9, since the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 8 is applied to a compact fluorescent lamp, it is different from a conventional compact fluorescent lamp. The luminous flux maintenance factor is improved.

According to the invention of claim 10, since the low-pressure mercury vapor discharge lamp according to any one of claims 1 to 9 is used as a light source of a lighting device, any one of claims 1 to 9. It is possible to provide a lighting device that makes use of the advantages of the lamp described in the above.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a light bulb shaped fluorescent lamp according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a phosphor coating formed on the inner surface of the arc tube of the embodiment.

[FIG. 3] Yttrium aluminate phosphor activated with chromium (Y
₃ is a characteristic diagram showing an emission spectrum of ₃ Al ₅ O ₁₂ ; Cr).

FIG. 4 is a characteristic diagram showing spectral energy distributions showing emission intensities of a chromium-activated yttrium aluminate phosphor and a conventional iron-activated lithium aluminate phosphor.

FIG. 5 is a characteristic diagram showing a luminous flux maintenance factor.

FIG. 6 is a diagram showing the amount of mercury consumed in the arc tube.

FIG. 7 is a characteristic diagram showing a change in mercury vapor pressure in a tube at the time of starting.

FIG. 8 shows a second embodiment of the present invention, and is a diagram showing a configuration of a bulb-type fluorescent lamp with an exposed arc tube.

9A and 9B show a third embodiment of the present invention, wherein FIG. 9A is a diagram showing a configuration of a straight tube type fluorescent lamp, and FIG. 9B is an enlarged sectional view of a portion B in FIG. 9A.

FIG. 10 is a configuration diagram showing an example in which the fluorescent lamp of the embodiment is used as a light source of an image reading device.

FIGS. 11A to 11C are configuration diagrams of different phosphor layers.

FIG. 12 is a characteristic diagram showing an emission spectrum of a Y ₃ Al ₅ O ₁₂ ; Eu phosphor.

FIG. 13 is a characteristic diagram showing an emission spectrum of a Y ₃ Ga ₅ O ₁₂ ; Cr phosphor.

FIG. 14 is a characteristic diagram showing an emission spectrum of a Gd ₃ Al ₅ O ₁₂ ; Cr phosphor.

FIG. 15 is a characteristic diagram showing an emission spectrum of a Gd ₃ Ga ₅ O ₁₂ ; Cr phosphor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube 2 ... Stem 3 ... Electrode 4 ... Lead wire 5 ... Capillary tube 6 ... Main amalgam 7 ... Auxiliary amalgam 10 ... Partition plate 12 ... Cover 13 ... Screw type base 15 ... High frequency lighting type electronic circuit device 16 ... Globe 20 ... Phosphor layer 21 ... Chromium activated yttrium aluminate phosphor (Y ₃
Al ₅ O ₁₂ ; Cr) layer 22 ... 3-wavelength light emitting rare earth phosphor layer 30 ... Protective layer made of metal oxide 50 ... Hot cathode type straight tube fluorescent lamp 51 ... Arc tube 54 ... Hot cathode electrode 57 ... Protective film 58 ... Phosphor layer for emitting near infrared rays 59 ... Visible light emitting phosphor layer 61 ... Reflector of image reading device 62 ... Original placement glass plate 63 ... Read original 64 ... Optical imaging lens system 65 ... Photoelectric conversion element

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ariyoshi Ishizaki 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Within Toshiba Litec Co., Ltd. (72) Mitsuru Shiozaki 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo No. Toshiba Lighting & Technology Co., Ltd. (72) Inventor Masaaki Tamaya, No. 1, Komukai Toshiba-cho, Sachi-ku, Kawasaki City, Kanagawa Prefecture

Claims (10)

[Claims] 1. A translucent airtight container in which electric discharge is generated and mercury and a rare gas are sealed; YAG provided on the inner surface of the airtight container and activated with at least one of chromium and europium. A low-pressure mercury vapor discharge lamp having a structure, and a phosphor layer containing a phosphor having an emission peak wavelength in a near-infrared region. 2. The low-pressure mercury vapor discharge lamp according to claim 1, wherein the phosphor having the YAG structure and having an emission peak wavelength in the near infrared region is mainly a chromium-activated yttrium aluminate phosphor. A low-pressure mercury vapor discharge lamp characterized in that 3. The low-pressure mercury vapor discharge lamp according to claim 1 or 2, wherein the phosphor layer has the YAG structure and has an emission peak wavelength in the near infrared region and an emission peak wavelength of A low-pressure mercury vapor discharge lamp comprising a phosphor in the visible light region. 4. The low-pressure mercury vapor discharge lamp according to claim 3, wherein the phosphor having an emission peak wavelength in the visible light region is a three-wavelength region emission type phosphor. . 5. The low-pressure mercury vapor discharge lamp according to claim 3 or 4, wherein the phosphor layer has the YAG structure in order from the wall surface side of the hermetic container, and the emission peak wavelength is in the near infrared region. A low-pressure mercury vapor discharge lamp, characterized in that the low-pressure mercury vapor discharge lamp is formed by a layer mainly composed of a phosphor and a layer mainly composed of the visible light emitting phosphor. 6. The low-pressure mercury vapor discharge lamp according to claim 1, wherein a protective layer made of metal oxide is provided between the inner surface of the airtight container and the phosphor layer. Low pressure mercury vapor discharge lamp. 7. The low-pressure mercury vapor discharge lamp according to claim 6, wherein the protective layer is Al ₂ O ₃ , TiO ₂ , SiO ₂ , ZnO,
A low pressure mercury vapor discharge lamp comprising at least one of CeO ₂ and Y ₂ O ₃ . 8. The low-pressure mercury vapor discharge lamp according to claim 1, wherein an amalgam is contained in the airtight container as mercury vapor pressure control means. Mercury vapor discharge lamp. 9. A low-pressure mercury vapor discharge lamp according to any one of claims 1 to 8 and a lighting circuit are integrated, and a bulb-type fluorescent lamp having a base to which the lighting circuit is connected. The low-pressure mercury vapor discharge lamp is characterized in that 10. A lighting device comprising the low-pressure mercury vapor discharge lamp according to claim 1 as a light source.