JP2000133199A - Low-pressure discharge lamp and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low power consumption type low-pressure discharge lamp, that makes an anode drop zero by efficiently collecting discharge currents, and a lighting system. SOLUTION: In a low-pressure discharge lamp having a translucent tube with a discharge medium sealed therein and a pair of discharge electrodes 3 sealed at both ends of the translucent tube, each of the discharge electrodes 3 has a discharge electrode main body 3a connected and supported at both ends by a pair of inner leads 3d, 3d', a conducting cylinder 3b surrounding the discharge electrode main body 3a and connected to the inner lead 3d, and an insulator 3c which has an aperture 3c' electrically connected to a positive column by the discharge of the discharge electrode main body 3a, and which is placed in the aperture of the cylinder 3b opposite thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure discharge lamp, and more particularly, to a low-pressure discharge lamp having reduced electrode power consumption during commercial frequency operation.

[0002]

2. Description of the Related Art Low-pressure discharge lamps are widely used in general lighting, light sources for office automation equipment, and pixel light sources for large screens. By the way, a low-pressure discharge lamp is generally filled with a discharge medium such as mercury and at least one rare gas in a light-transmitting tube (for example, a glass bulb) provided with a phosphor film on an inner wall surface. The positive column discharge is generated in the discharge medium. Specifically, a hermetically sealed glass tube having a phosphor layer provided on an inner wall surface thereof, mercury and at least one rare gas sealed in the glass tube, and a rare gas sealed in the glass tube. It has a configuration including a pair of electrodes that generate a positive column discharge in a gas.

[0003] In the low-pressure discharge lamp, the electrodes are usually preheated by alternating current at a commercial frequency, and are maintained by supplying electric energy to a discharge medium through emission (starting) of the electrodes. For example, for a low-pressure fluorescent lamp,
The cathode is preheated by energizing the opposing electrodes,
Thermoelectrons are emitted from the electron-emitting substance (emitter) carried, and plasma discharge is started in the glass tube. Ultraviolet light (254 nm) is mainly radiated by the resonance radiation of the mercury atoms excited by the discharge energy, and the ultraviolet light is converted into a long wavelength by the phosphor film on the inner wall surface of the glass tube to function as a fluorescent lamp. Here, when the discharge medium directly emits visible light, the formation of the phosphor film can be omitted.

[0004] Conventionally, electron-emitting materials (emitters)
For example, an oxide obtained by adding a small amount of zirconium oxide to at least one oxide of barium oxide, calcium oxide, and strontium oxide is used. Further, the emission wavelength of the fluorescent lamp depends on the type of phosphor particles contained in the phosphor layer, and wavelengths from near ultraviolet to visible to near infrared have been obtained. Further, the light-transmitting tube (for example, a glass bulb) is not limited to a straight tube type, but may be a circular shape, a U shape, a saddle shape, or the like.
Many shapes are also complicated.

[0005]

In a low-pressure discharge lamp (for example, a fluorescent lamp), the power consumed by the electrodes is affected by the loss caused by the cathode drop and the anode drop. For example, at the anode, a current determined by current = area of anode × electron density × electron speed × 1/4 flows (discharge current). Here, the speed of the electrons is determined by the heat speed or the accelerating voltage at the anode falling part,
In addition, the electron density hardly fluctuates with time at several kHz or more, and the high-density plasma generated in the cathode cycle maintains a high value even in the anode cycle. Become. Therefore, the electrodes can collect the required discharge current, so that the anode drop becomes zero and the luminous efficiency in high-frequency lighting increases, but in commercial frequency lighting, the anode drop becomes zero as the anode drop becomes zero. Electron density does not increase.

On the other hand, as can be seen from the above equation, it is considered that by increasing the area of the anode, the discharge current can be collected even when the electron density is low, so that the anode drop can be reduced to zero. However, in practice, in order to reduce the anode drop to zero, the anode must be set larger than necessary, but there is still a problem in efficiency.

That is, in a simple plate-shaped anode or a cup-shaped anode, electrons are exclusively collected at the end near the positive column, and the entire area is not effectively used. In particular, in the case of a cup-shaped anode, light emission near the negative glow is sacrificed, which causes a problem that light efficiency is reduced.

The present invention has been made in view of the above circumstances, and provides a low-power-consumption type low-pressure discharge lamp and a lighting device that efficiently collect a discharge current and reduce the anode drop to zero. Aim.

[0009]

According to a first aspect of the present invention, there is provided a low-pressure lamp comprising: a light-transmitting tube having a discharge medium sealed therein; and a pair of discharge electrodes sealed at both ends of the light-transmitting tube. A discharge lamp, wherein the discharge electrode has a pair of inner leads connected and supported at both ends by a pair of inner leads; and a conductive cylinder surrounding the discharge electrode body and connected to the inner leads; A discharge in the vicinity of the discharge electrode main body having an opening connected to the positive column, and an insulator disposed at an opposite opening of the cylindrical body.

According to a second aspect of the present invention, in the low-pressure discharge lamp according to the first aspect, a phosphor film is formed on an inner wall surface of the light-transmitting tube that seals the discharge medium.

According to a third aspect of the present invention, in the low-pressure discharge lamp according to the first or second aspect, the cylinder of the discharge electrode is:
A transparent conductive film is formed on at least the inner wall surface of a light-transmitting material.

According to a fourth aspect of the present invention, in the low-pressure discharge lamp according to any one of the first to third aspects, the insulator disposed at the opening of the cylindrical body of the discharge electrode has at least a surface facing the anode column. In which a metal oxide film is formed.

The inventions of claims 1 to 4 are characterized by the structure of the discharge electrode sealed in the light-transmitting tube. That is, the discharge electrode body is surrounded by a cylindrical body having conductivity, and the cylindrical body is connected to the inner lead, and the discharge near the discharge electrode is electrically connected to the positive column at the opposite opening of the cylindrical body. In this configuration, an insulator having an opening is provided.

Here, the discharge electrode body is generally of a filament type such as a double coil or stick coil made of tungsten, for example. And barium oxide,
Applying (supporting) barium tungsten oxide, zirconium oxide, tantalum oxide, etc. with low vapor pressure, such as calcium oxide, strontium oxide, etc. to which a small amount of zirconium oxide is added, as an electron-emitting substance (emitter) I do. The electrode body may be a sintered (ceramic) electrode in which an emitter material that emits thermoelectrons by heating by electric discharge is sintered.

The conductive cylinder surrounding the discharge electrode main body is made of a metal such as nickel, iron or stainless steel, or has at least an inner wall surface coated with a tin oxide or indium oxide film. It is made of glass. The cylindrical body itself may be a simple cylindrical type, but it is preferable that both open ends are reduced in diameter (narrowed).

When the cylindrical body is entirely made of a metal having conductivity, it is preferable to coat the outer peripheral surface with an insulator, and the electrical connection between the conductive body and the inner lead is made. The position of the proper connection is not particularly limited.

Further, the insulator disposed at the opening facing the cylindrical body is, for example, a heat-resistant insulator such as mica, or a surface formed by coating a heat-resistant insulating film such as a metal oxide. The insulator needs to be opened at a substantially central portion so that the discharge near the discharge electrode is electrically connected to the positive column.

In the first to fourth aspects of the present invention, a low-pressure discharge lamp, for example, a fluorescent lamp, generally comprises a hermetic sealing type translucent tube, which is a glass bulb, provided with a phosphor film on an inner wall surface thereof. is there. The phosphors forming the phosphor film are, for example, SrB ₄ O ₇ : Eu ²⁺ , Sr ₁₀ (PO ₄ ) ₆ Cl ₁₂ :
Eu ²⁺ , (Sr, Ca) ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu ²⁺ , (Sr, Ca,
Ba) ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu ²⁺ , (La, Ce, Tb) PO ₄ , Y
₂ SiO ₅ : Ce, Tb, Zn ₂ SiO ₄ : Mn, Y ₂ O ₃ : Eu ³⁺ ,
Any phosphor usually used in the construction of a fluorescent lamp, such as YVO ₄ Y (P, V) O ₄ : Eu ³⁺ , may be used.

The discharge medium sealed in the hermetically sealed light-transmitting tube includes mercury, for example, neon, argon, krypton, xenon, and a mixed gas of these rare gases. On the other hand, the translucent tube is not limited to a straight tube type, but may be a circular shape, a U shape, a saddle shape, or the like.

According to a fifth aspect of the present invention, there is provided a lighting device comprising: a lighting device; and the low-pressure discharge lamp according to any one of the first to fourth aspects mounted on the lighting device. is there.

Here, the lighting equipment has a built-in lighting circuit, and is generally configured as a detachable type to which a low-pressure discharge lamp can be attached and detached, but it is also possible to adopt a configuration in which both are integrated. it can.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.

FIGS. 1, 2 and 3 show the main parts of the low-pressure discharge lamp according to the first embodiment. FIG. 1 is a partially cutaway sectional view, and FIG. 3 is a developed perspective view of the discharge electrode section. In the figure, 1 is a straight tube type glass tube that seals a discharge medium (rare gas, mercury, etc.), 2 is a phosphor film formed on the inner wall surface of the glass tube 1, 3 is both ends of the glass tube 1 Are a pair of discharge electrodes sealed respectively, and 4 is a base.

The glass tube 1 has an inner diameter of 24 m, for example.
m, a straight tube having a length of 1200 mm, and the phosphor film 2 is a mixture of three kinds of phosphors having emission regions of blue, green and red.
It is a wavelength type phosphor layer. The discharge electrode 3 has a discharge coil body 3a formed by applying an alkaline earth oxide to a triple coil made of tungsten, and an inner diameter of 16 mm, a height of 12 mm, and a thickness of about 0.2 mm with both ends being reduced in diameter. Nickel cylinder 3b
With a thickness of 1mm and an outer diameter of about 15.5mm
Mica insulating disc 3c with circular opening 3c 'of about 5mm
It is composed of

That is, a pair of inner leads 3d, 3d '
The discharge electrode main body 3a, both ends of which are connected and supported, is surrounded by a nickel cylindrical body 3b connected to one inner lead 3d, and the discharge of the discharge electrode main body 3a is electrically connected to a positive column. Further, the insulating disc 3c is integrally arranged in the facing opening of the nickel cylinder 3b. Here, the connection of the nickel cylinder 3b to the inner lead 3d is performed by connecting the tongue piece 3b 'to the nickel cylinder 3b in advance.
And the connecting tongue piece 3b ′ is connected to the inner lead 3d.
This is done by spot welding. Further, the integral arrangement of the insulating disc 3c with respect to the nickel cylinder 3b can be performed by clamping the nickel cylinder 3b at a reduced diameter portion of the opening.

Further, the discharge electrode body 3a and the like are sealed at the opening end of the glass tube 1 with a flare 3f with an exhaust pipe 3e that leads the inner leads 3d and 3d 'as airtight outer leads. After sealing and exhaust, the exhaust pipe 3e is sealed off. Further, the base 4 is provided with terminal pins 4a and 4b which are electrically connected to the outer leads.

The fluorescent lamp 5 having the above-described structure includes the terminal pins 4a,
When a current is applied to each of the discharge electrodes 3 via 4b, the discharge electrodes 3
Discharge starts between them, emitting ultraviolet light. Then, this ultraviolet light is converted into visible light by the phosphor film 2 and functions as a fluorescent lamp with high luminous efficiency. That is, this kind of fluorescent lamp is used as a light source by being assembled and mounted on a lighting fixture 6 as shown in FIG. In FIG. 4, reference numeral 6a denotes a lighting fixture body having a built-in lighting circuit 6b, and 6c denotes a socket portion for engaging and mechanically holding each of the terminal pins 4a and 4b at both ends of the fluorescent lamp 5 in engagement. It is.

In the lighting process by this lighting device, since the insulating disk 3c is electrically insulating, electrons are not collected by the insulating disk 3c and the insulating disk 3c is Electrons enter the inside of the nickel cylinder 3b through the opening 3c '. At this time, the opening 3c 'of the insulating disc 3c
However, since it is smaller than the cross-sectional area of the glass tube 1, the electric field strength at the portion passing through the opening 3c 'of the insulating disk 3c sharply increases, and the electron density increases.

Therefore, the electrons are collected in the nickel cylinder 3b in a state where the electron density is sufficiently high, so that the current necessary for the discharge is collected without the anode drop. Further, in the structure of the discharge electrode 3, since no electrons are collected at the end of the nickel cylinder 3b facing the positive column, the entire inner wall surface of the nickel cylinder 3b can be effectively used. . That is, the fluorescent lamp in which the discharge electrode 3 is sealed according to the present invention achieves both high efficiency by eliminating the anode drop and effective light use efficiency improvement by minimizing the area of the discharge electrode 3 at the same time. Can be.

As a second embodiment, in the structure of the above-mentioned fluorescent lamp, a glass cylinder is used as a base instead of the nickel cylinder 3b, and a conductive transparent film (for example, an indium oxide film) is provided on the inner wall surface. In the case of using such a material, the light emission of the negative glow can be used more effectively, so that the efficiency can be further improved. Also, the insulating disc 3c may be made of soda glass or lead glass instead of mica, and in the case of these glasses, the surface is coated with a metal oxide film such as alumina or yttria. If this is done, the penetration of mercury into the glass can be prevented, so that the transparency is maintained even when the lamp is operated for a long time, and the luminous flux maintenance rate is improved.

FIG. 5 is a sectional view showing the structure of a main part of a low-pressure discharge lamp according to a third embodiment.

In the discharge lamp of this embodiment, a dumet wire (introduction wire: outer lead and inner lead) is formed at both ends of a glass bulb 1 which forms a straight tube and has a translucent container having an outer diameter of about 3 to 15 mm, for example. A ceramic electrode 8 as a hot cathode to which 7 is connected is sealed facing each other at a separation distance of 260 mm, and a mixed gas of argon gas and mercury vapor as a discharge medium is filled in the glass bulb 1 as a filling gas. It is enclosed.

Here, the ceramic electrode 8 is a nickel-bottomed cylindrical holding member 8a having an open end, and is coaxially mounted in the holding member 8a. It comprises a cup 8b, granules (diameter: about 10 to 100 μm) 8c serving as thermionic radiators housed in the cup 8b, and an insulating disc 8d arranged in the opening of the cup 8b. The insulating disk 8d is a ceramic electrode 8
5 mm, and has an outer diameter enough to cover the opening end face of the holder 8a, and is disposed corresponding to the opening of the cup 8b. The circular plate 8d is provided with a circular opening 8d 'having a diameter of about 5 mm at the center so that the discharge is electrically connected to the positive column.

The holder 8a is not limited to nickel,
For example, the material may be tantalum, titanium, zirconium, aluminum, tungsten, an alloy containing one or more of these, or a material containing a nitride or oxide of the metal. Furthermore, thermionic emitters are mainly composed of, for example, a mixture of barium tantalic acid and a small amount of zircon oxide, and have a surface coated with a conductive thin film made of tantalum carbide or the like to improve spatter resistance. No.

The cup 8b coaxially mounted in the holder 8a is locked by bending a plurality of extensions 8a 'protruding from the opening end face of the holder 8a. That is,
The extended portion 8a 'of the holder 8a is bent inward at a substantially right angle to lock the opening end surface of the cup 8b, thereby preventing the cup 8b from moving or detaching in the axial direction, and also contributing to glow discharge and the like.
Next, the operation of the discharge lamp will be described.

When the discharge lamp is turned on, thermoelectrons are emitted between the opposed hot cathodes 8 and 8 respectively, and discharged between the hot cathodes 8 and 8 and irradiated with ultraviolet rays having a wavelength of 254 nm by mercury. The phosphor film 2 converts the light into visible light. The hot cathode 8 performs glow discharge as a cold cathode at the start of startup, and ions accelerated by a high cathode drop voltage heat the entire ceramic electrode 8 to increase the temperature.

On the other hand, the thermoelectron radiator 8c is granular and has a small heat capacity, and also has a high thermal resistance to the adjacent granules 8c, so that it is easy to raise the temperature. When the temperature reaches a temperature at which the particles can be released, the glow is transferred to an arc, a cathode luminescent spot is formed in the granules 8c, and the granules 8c are transferred to the cathode.

In this lighting operation, the side of the hot cathode 8 connected to the positive column is electrically insulated by the insulating disc 8d, so that electrons are not collected by the insulating disc 8d.
Electrons enter the inside of the cup 8b through the opening 8d 'of the insulating disk 8d. At this time, the opening of the insulating disc 8d
Since 8d 'is smaller than the cross-sectional area of the glass tube 1, the electric field intensity at the portion passing through the opening 8d' of the insulating disk 8d sharply increases, and the electron density increases.

Therefore, the electrons are collected in the cup 8b while the electron density is sufficiently high, so that the current necessary for the discharge is collected without the anode drop. The hot cathode 8
In the structure (1), electrons are not collected at the end of the cup 8b facing the positive column, so that everything in the cup 8b can be effectively used. That is, the discharge lamp in which the hot cathode 8 according to the present invention is sealed achieves both high efficiency by eliminating the electrode drop and effective light use efficiency improvement by minimizing the area of the hot cathode 8 at the same time. Can be.

In the above description, a fluorescent lamp or the like having a structure in which the phosphor film 2 is formed on the inner wall surface of the glass tube 1 has been described, but a structure in which a rare gas containing xenon is sealed as a discharge medium or a structure in which sodium is sealed is used. Similarly,
It has low power consumption and high efficiency, and has a long life.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. For example, the outer diameter, wall thickness,
The length, the shape, thickness, and length of the cylindrical body, the type of the phosphor forming the phosphor layer, and the like can be appropriately selected.

[0042]

According to the first aspect of the present invention, it is possible to provide a low-pressure discharge lamp which is economical because it can simultaneously reduce the interruption of light emission at the discharge electrode and the power consumption of the electrode.

According to the second aspect of the present invention, a fluorescent lamp of a low power consumption and high efficiency light emitting type can be provided.

According to the third aspect of the present invention, since the interruption of light emission at the discharge electrode portion is more effectively reduced, the reduction in electrode power consumption is achieved at the same time, and further practical use is achieved. A low-pressure discharge lamp with excellent properties can be provided.

According to the fourth aspect of the present invention, since the reduction in electrode power consumption is maintained for a longer period of time, a low-power-consumption, high-efficiency light-emitting fluorescent lamp with excellent durability can be provided. .

According to the invention of claim 5, the light efficiency is high,
In addition, since a low-pressure discharge lamp having reduced electrode power consumption is used as a light source, an economically effective lighting device can be provided.

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view showing a schematic configuration of a fluorescent lamp according to an embodiment.

FIG. 2 is an enlarged cross-sectional view showing a configuration of a discharge electrode unit of the fluorescent lamp according to the embodiment.

FIG. 3 is an enlarged perspective view showing a configuration of a discharge electrode sealing portion of the fluorescent lamp according to the embodiment.

FIG. 4 is a side view showing a schematic configuration of a lighting device according to the embodiment.

FIG. 5 is a sectional view showing a configuration of a main part of the discharge lamp according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass tube 2 ... Phosphor film 3 ... Discharge electrode 3a ... Discharge electrode main body (coil) 3b ... Conductive cylinder (cup) 3b '... Connection tongue 3c ... Insulating disc (Mica plate) 3c ': Opening (hole) of insulating disk 3d, 3d': Inner lead 3e: Exhaust tube 3f: Flare 4: Base 4a, 4b: Terminal pin 5: Low-pressure fluorescent light Lamp 6: Lighting device 6a: Lighting device body 6b: Lighting circuit 6c: Socket part 7: Lead wire (inner lead and outer lead) 8: Hot cathode (ceramic electrode)

Claims (5)

[Claims] 1. A low-pressure discharge lamp comprising: a light-transmissive tube having a discharge medium sealed therein; and a pair of discharge electrodes sealed at both ends of the light-transmissive tube, respectively. A discharge electrode main body connected and supported at both ends by a pair of inner leads; a conductive cylinder surrounding the discharge electrode main body and connected to the inner leads; and a discharge near the discharge electrode main body becomes a positive column. And an insulator disposed at an opposing opening of the cylindrical body. 2. The low-pressure discharge lamp according to claim 1, wherein a phosphor film is formed on an inner wall surface of the light-transmitting tube that seals the discharge medium. 3. The low-pressure discharge lamp according to claim 1, wherein the cylindrical body of the discharge electrode is made of a translucent material and a transparent conductive film is formed on at least an inner wall surface. 4. The insulator disposed at the opening of the cylindrical body of the discharge electrode has a metal oxide film formed on at least a surface facing the positive column. The low-pressure discharge lamp according to any one of the above. 5. A lighting device, comprising: a lighting device; and the low-pressure discharge lamp according to claim 1 mounted on the lighting device.