JPH11288687A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp which can be turned on by use of simple constitution and which utilizes negative glow. SOLUTION: A discharge lamp 1 has an arc tube 2 with a discharge medium sealed therein, a pair of lead wires 5 introduced into the tube 2, a pair of electrodes 6 disposed at the lead wires 5 while in a positional relationship such that a negative glow discharge can be brought about, and a filament 7 electrically connected at each end to the parts of the lead wires 5 near the pair of electrodes 6 and having an emitter applied thereto, the filament 7 having a cold resistance of 5 Ω or more and an electrode-to-electrode distance of 5 mm to 50 mm. When a voltage is applied between the lead wires 5, a current flows in the filament 7 between the electrodes 6 and thermoelectrons are radiated. When the filament resistance rises as the temperature of the filament 7 rises, the filament 7 becomes resistant to the flow of currents therein and a glow discharge is brought about between the electrodes 6. The discharge lamp 1 starts to emit light because of the glow discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a discharge lamp utilizing glow discharge.

[0002]

2. Description of the Related Art Most of fluorescent lamps widely used as light sources for general lighting are lit by arc discharge, and emit light using ultraviolet rays radiated from mercury by this discharge. .

[0003] The arc discharge is generally divided into a cathode descending part, a negative glow, a Faraday dark part, a positive column, an anode glow and an anode descending part, and the fluorescent lamp mainly uses the light emitted from the positive column.

Various studies have been conducted on arc discharge because of its high luminous efficiency. However, since a high voltage is required for dielectric breakdown of a discharge space, simplification and miniaturization of a lighting circuit are limited. there were.

On the other hand, the negative glow of the arc discharge also emits light at a relatively high intensity. For example, a fluorescent lamp utilizing negative glow light emission as described in Japanese Patent Application Laid-Open No. 3-84844 has been studied.

In this fluorescent lamp, a pair of hot cathodes composed of a filament are sealed in an arc tube, and by heating the filament, thermoelectrons are emitted to generate a glow discharge. It is described that since the fluorescent lamp has a low lamp voltage of about 20 V, it can be turned on with a relatively simple circuit configuration.

[0007]

In a conventional fluorescent lamp utilizing negative glow light emission, a filament for thermionic emission is provided on a pair of electrodes, and a lighting circuit for heating a filament is provided separately from a discharge circuit. Circuit was also required.

An object of the present invention is to solve the above-mentioned problems and to provide a discharge lamp utilizing negative glow light emission which can be turned on with a simple structure.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp comprising: an arc tube in which a discharge medium is sealed; a pair of lead wires introduced into the arc tube; At least a pair of electrodes arranged in a possible positional relationship; a cold resistance of not less than 5Ω, both ends of which are electrically connected to a lead wire near the pair of electrodes and an emitter applied, and a distance of not less than 5 mm between the electrodes And a filament of 50 mm or less.

In this claim and the following claims, the definition of each component is as follows, and a well-known configuration can be applied to a component that is not particularly defined.

The arc tube is made of a glass material such as soda lime glass, lead glass, borosilicate glass, quartz glass, etc.
It is made of a translucent ceramic or the like.

The discharge medium is sealed in the arc tube at a pressure that allows glow discharge, and a desired gas type is selected.

The filament is made of a high melting point metal material such as tungsten (W).
(r, Ca) An emitter material made of a material such as CO ₃ is applied. In addition, it is also possible to use a means for emitting thermoelectrons by heating and increasing the resistance value by replacing the filament with a filament.

The operation of the discharge lamp of claim 1 will be described. First, when a voltage is applied between the lead wires, a current flows through the filament between the two electrodes, and the filament is heated to emit thermoelectrons. When the resistance value of the filament increases as the temperature of the filament increases, it becomes difficult for a current to flow through the filament, and a negative glow is generated between the electrodes to generate a glow discharge. The discharge lamp starts to emit light due to the glow discharge. The filament has a cold resistance of 5 Ω or more, the distance between the electrodes is 5 mm or more and 50 mm or less, and the high resistance value reduces the power loss due to the filament, improves the lighting efficiency, and the distance between the electrodes facilitates glow discharge. , The discharge becomes stable.

According to a second aspect of the present invention, in the discharge lamp of the first aspect, the discharge medium is made of at least one of Ne, Ar, Kr, and Xe.

According to the discharge lamp of the second aspect, visible light is emitted among the resonance lines of the gas by the glow discharge. The type of gas to be filled as a discharge medium may be appropriately selected according to a desired emission color.

The discharge medium has a gas atomic weight of Ne to Xe.
In the case of an arc discharge fluorescent lamp, the larger the value becomes, the worse the startability of the lamp becomes. However, in this case, the use of glow discharge does not affect the startability, and a gas having a large atomic weight can be sealed. Also, the pressure of the filled gas can be increased.

Further, a phosphor layer may be formed in the arc tube, and visible light may be emitted by ultraviolet light emission among the resonance lines of the gas.

A third aspect of the present invention is the discharge lamp according to the first or second aspect, wherein the discharge medium comprises mercury and a rare gas,
The light emitting tube is characterized in that a phosphor layer is formed.

According to the discharge lamp of the third aspect, the phosphor layer emits visible light by radiating ultraviolet light which is a part of the resonance line of mercury, and can be efficiently lit to a desired emission color.

According to a fourth aspect, in the discharge lamp according to any one of the first to third aspects, a cover for supporting the arc tube is provided, and a lighting circuit is provided in the cover.

The cover includes one integrated with the base.

According to the fourth aspect of the present invention, since the lighting circuit necessary for lighting the discharge lamp is integrated, the size can be further reduced, and a bulb-type fluorescent lamp which can be substituted for an incandescent bulb is provided. It is also possible to do.

According to a fifth aspect of the present invention, in the discharge lamp according to any one of the first to fourth aspects, the pair of electrodes are disposed in a longitudinal direction of the arc tube.

According to the discharge lamp of the fifth aspect, when the discharge medium is composed of mercury and a rare gas and the phosphor layer is formed on the arc tube, a large amount of gas resonance lines act on the phosphor layer. Of these, ultraviolet rays can cause the phosphor layer in the arc tube to emit light effectively.

According to a sixth aspect of the present invention, there is provided the discharge lamp according to any one of the first to fifth aspects, further comprising: a cover for supporting the arc tube; and a base, wherein the coolest part of the arc tube is introduced into the cover or the base. It is characterized in that a heat conductive material is disposed in contact with the introduction portion.

According to the discharge lamp of the present invention, since the heat conductive material is disposed in the coldest part, the heat conductive material acts as a coolant, and the heat in the coldest part can be radiated well.

According to a seventh aspect of the present invention, in the discharge lamp according to any one of the first to sixth aspects, the lamp is lit by a DC power supply, and the cathode portion of the pair of electrodes is disposed substantially at the center of the arc tube. It is characterized by.

According to the discharge lamp of the seventh aspect, since the cathode portion is disposed substantially at the center of the arc tube, uniform light emission can be obtained.

An eighth aspect of the present invention is the discharge lamp according to any one of the first to seventh aspects, wherein an insulator is interposed between the pair of electrodes. As an insulator,
Mica, transparent glass, and the like can be appropriately selected.

According to the discharge lamp of the eighth aspect, the discharge path becomes longer, the arc discharge can be used in addition to the glow discharge, and the total luminous flux can be improved.

[0032]

1 to 3 show a first embodiment of a discharge lamp according to the present invention.

FIG. 1 is a sectional view of a bulb-type fluorescent lamp which is a first embodiment of the discharge lamp of the present invention.

A discharge lamp 1 has an arc tube 2 made of soda-lime glass. The arc tube 2 has a maximum outer diameter of about 3
5mm, PS like bulb shape for incandescent bulb
(Pearshape) It has a shape. Phosphor layer 3 on the inner surface
Are formed.

A stem 4 is sealed to the end of the arc tube 2, and a pair of lead wires 5 is introduced by the stem 4.

At the tip of the lead wire 5 in the arc tube 2, an electrode portion 6 integral with the lead wire 5 is provided. An end of the filament 7 is electrically connected near the electrode section 6.

The axial length of the filament 7 is about 15 m
m, and both ends are electrically connected by clamping the leading end of the lead wire 5. Filament 7
In order to easily release thermoelectrons, (Ba, Sr,
Ca) an emitter material consisting of CO ₃ is applied.

In the arc tube 2, an inert gas such as argon (Ar) and mercury are sealed as a discharge medium.

Reference numeral 8 denotes a cylindrical cover made of a PBT resin. The stem 4 side of the arc tube 2 is fixed at one opening with a silicone adhesive or the like, and the E-shaped base 9 is fitted at the other opening. Is formed. A high-frequency lighting circuit 10 for lighting the discharge lamp 1 is accommodated in the cover 8, and a lead wire 5 derived from the discharge lamp 1 is connected thereto, and a power supply line is connected to the base 9.

Here, a ballast choke is usually mounted on the lighting circuit 10 in order to stabilize the discharge current. In the discharge lamp of the present embodiment, in the glow or end glow state, the filament electrode itself becomes a current stabilizer. Therefore, no ballast choke for the circuit is required.

Next, the operation of the present embodiment will be described. First, when a voltage is applied between the lighting circuit 10 and the lead wire 5, a current flows through the filament 7 between the two electrodes 6, and the filament 7 emits thermoelectrons. Filament 7
When the temperature exceeds a certain temperature, it becomes difficult for a current to flow through the filament due to an increase in the filament resistance value, so that a negative glow is generated between the pair of electrodes 6 to generate a glow discharge. The discharge voltage at this time is about 10 V, and the lamp power is about 3
W.

The discharge lamp starts to emit light due to the glow discharge. Although the negative glow mainly occurs between the electrodes 6,
Depending on the shape and positional relationship of the electrode 6, glow discharge may occur in other places.

The glow discharge of the discharge lamp 1 emits mainly 254 nm ultraviolet rays which are a part of the mercury resonance line, and the ultraviolet rays excite the phosphor layer 3 to emit visible light.

The filament 7 of the discharge lamp 1 is
Since the cold resistance is as high as 5Ω or more, the power loss due to the filament 7 is reduced, and the lighting efficiency is improved.

According to the bulb-type fluorescent lamp of this embodiment,
Even in a discharge lamp utilizing negative glow light emission at low power, a filament for thermionic emission is provided between the electrodes 6, so that the number of parts is reduced and the lighting circuit is provided separately from the discharge circuit. There is no need to provide a heating circuit, and the lighting circuit can have a simple configuration.

FIG. 2 is a graph showing the relationship between the filament resistance and the filament current at which negative glow occurs.
FIG. 3 is a graph showing the relationship between the filament resistance value and the luminous efficiency (lm / W). The filament resistance is a measured value as a cold resistance.

The filament 7 sealed in the arc tube 2 is
In order to easily generate glow discharge with low power, the resistance value is set to 5Ω or more, and the length of the filament 7 is set to 5 mm or more and 50 mm or less in the axial direction for stabilization of glow discharge and strength characteristics of the filament.

By increasing the filament resistance, a negative glow can be generated with a small filament current. This contributes to downsizing of the circuit. Further, since the power loss due to the filament is reduced, the luminous efficiency can be improved. When the filament resistance exceeds 10Ω, the decrease in the filament current and the increase in the luminous efficiency do not change so much. Therefore, the filament resistance is preferably set to 10Ω or less. Since the characteristics are considered to change, in such a case, it may be 10Ω or more.

The discharge medium of the discharge lamp of this embodiment is a rare gas such as mercury and argon (Ar).
Neon (Ne), argon (Ar), krypton (K
r), one of the rare gases of xenon (Xe) or a mixed gas obtained by combining these. By glow discharge using a rare gas as a discharge medium, visible light can be emitted from the resonance lines of the rare gas. The type of the rare gas sealed as the discharge medium can be selected according to a desired emission color.

Next, FIGS. 4 to 8 show second to sixth embodiments of the discharge lamp of the present invention. 4 to 8
1 is a sectional view of a bulb-type fluorescent lamp which is an embodiment of a discharge lamp of the present invention. The difference from the first embodiment is mainly the arrangement of the electrodes, and the other configurations are the same.
The same reference numerals are given to the same portions as those of the embodiment, and the detailed description thereof will be omitted. First, FIG. 4 shows a second embodiment,
In the arc tube 2, one lead wire 5a on the stem 4 side and the other lead wire 5b are introduced. One lead wire 5 a extends from the stem 4 toward the inside of the arc tube 2, and is bent in the middle toward the long axis direction of the arc tube 2. The other lead wire 5b extends from the stem 4 to the vicinity of the top of the arc tube 2 along the long axis of the arc tube 2, and is bent inward in the middle.

At the tip of each of the lead wires 5a and 5b, a pair of electrode portions 6a and 6b are provided integrally with the lead wires 5a and 5b so as to face each other along the long axis direction of the arc tube 2.
In the vicinity of a and 6b, both ends of the filament 7 are electrically connected. The electrical connection of the filament 7 is made simultaneously with the mechanical holding by clamping the tips of the lead wires 5a, 5b.

Next, FIG. 5 shows a third embodiment. In the second embodiment, the case where a pair of electrode portions is provided has been described. In this embodiment, two pairs of electrode portions are provided. .

At the tips of the lead wires 5c and 5d, two pairs of electrode portions 6c, 6d and 6e are integrally formed with the lead wires 5c and 5d.
The electrodes 6c, 6d, 6e, and 6f are in parallel with each other along the longitudinal axis of the arc tube 2.

Further, both ends of the filaments 7a and 7b are electrically connected in the vicinity of the electrode portions 6c, 6d and 6e, 6f. The filaments 7a and 7b are electrically connected by connecting the distal ends of the lead wires 5c and 5d to the filament 7a.
This is done by winding around the ends of a and 7b and clamping the tip. By the above, filament 7
a and 7b are disposed along the long axis direction of the arc tube 2 and parallel to each other.

FIG. 6 shows a fourth embodiment, in which a pair of electrode portions 6g and 6h are attached to the tips of the lead wires 5e and 5f integrally with the lead wires 5e and 5f with respect to the long axis of the arc tube 2. 30
The arc tube 2 is provided so as to face each other along the major axis direction of the arc tube 2 at an angle.

Next, the operation of the second embodiment will be described. First, when a voltage is applied to the lead wires 5a and 5b from the lighting circuit 10, a negative glow is generated between the pair of electrode portions 6a and 6b, and a glow discharge is generated. Here, the electrode section 6
glow discharge generated between the electrodes 6a, 6b
Since b is provided along the major axis direction of the arc tube 2 so as to face the outer ring, the outer ring is bulged in the circumferential direction of the major axis of the arc tube 2 (shown by a broken line in FIG. 4).

The glow discharge radiates ultraviolet rays, which are mercury resonance lines, and excites the phosphor layer 3 to generate visible light.

The luminous intensity of the phosphor layer due to ultraviolet rays increases as the distance between the glow discharge portion and the phosphor layer decreases. In addition, the larger the surface area of the outer ring of the glow discharge portion facing the phosphor layer surface formed in the arc tube, that is, the larger the circumferential surface area, the more ultraviolet rays that are resonance lines act on the phosphor layer, and the phosphor layer is formed. It can emit light effectively.

Therefore, according to the present embodiment, since the electrode portions 6a and 6b are provided so as to face each other along the long axis direction of the arc tube 2, the distance between the glow discharge portion and the phosphor layer 3 is reduced, and the fluorescent light is emitted. Since the circumferential surface area of the glow discharge portion facing the body layer 3 is large, the phosphor layer 3 in the arc tube 2 can emit light effectively.

In the third and fourth embodiments, the phosphor layer 3 in the arc tube 2 can be made to emit light effectively by the same operation as in the second embodiment.

FIGS. 7 and 8 show the fifth and sixth embodiments. The arrangement of the electrodes is the same as that of the second embodiment. This will be mainly described.

First, FIG. 7 shows a fifth embodiment, in which the opening of a cylindrical cover 8 made of PBT resin is fixed to the stem 4 side of the arc tube 2 with a silicone adhesive or the like. An E-shaped base 9 is fitted in the other opening of the cylindrical cover 8.

In the space formed by the cylindrical cover 8 and the base 9, the partitioning plate 11 is located near the opening of the cylindrical cover 8.
And a high-frequency lighting circuit 10 for lighting the discharge lamp 1 is housed at a predetermined interval from the partition board 11.

The lighting circuit 10 includes a printed circuit board 10a
And a circuit element 10b such as a capacitor and a transistor disposed on the printed circuit board 10a. Here, through holes are formed in the partitioning board 11, and through these holes, an exhaust pipe 12 and lead wires 5 a and 5 b extending from the stem 4 constituting the coldest part of the arc tube 2 penetrate. I have.

The exhaust pipe 12 is a thin tube and extends almost to the center of the space formed by the partition board 11 and the printed circuit board 10a. The amalgam 13 is accommodated in the exhaust pipe 12.
On the other hand, the space is filled with a heat conductive substance 14 such as a silicone adhesive.

The lead wires 5 a and 5 b derived from the discharge lamp 1 and the power supply line derived from the base 9 are connected to a high-frequency lighting circuit 10.

Next, FIG. 8 shows a sixth embodiment, which has substantially the same configuration as that of the fifth embodiment. An opening of a cylindrical cover 8 made of PBT resin is fixed to the stem 4 side of the arc tube 2 with a silicone adhesive or the like, and an E-shaped base 9 is fitted into the other opening of the cylindrical cover 8. .

In the space formed by the cylindrical cover 8 and the base 9, the partitioning plate 11 is located near the opening of the cylindrical cover 8.
And a high-frequency lighting circuit 10 for lighting the discharge lamp 1 is housed at a predetermined interval from the partition board 11.

The lighting circuit 10 includes a printed circuit board 10a
And a circuit element 10b such as a capacitor and a transistor disposed on the printed circuit board 10a. Here, through holes are formed in the partitioning board 11, and through these holes, an exhaust pipe 12 and lead wires 5 a and 5 b extending from the stem 4 constituting the coldest part of the arc tube 2 penetrate. I have. Further, a through hole is formed substantially at the center of the printed circuit board 10a, and the through hole is formed in the through hole.
An exhaust pipe 12 extending through a space formed by the printed circuit board 1 and the printed circuit board 10a penetrates.

The exhaust pipe 12 has a thin tubular shape and accommodates the amalgam 13, while the space formed by the printed circuit board 10 a and the base 9 is filled with a heat conductive substance 14 such as a silicone adhesive. .

The lead wires 5 a and 5 b derived from the discharge lamp 1 and the power supply line derived from the base 9 are connected to a high-frequency lighting circuit 10.

Next, the operation of the fifth and sixth embodiments will be described. Also in the present embodiment, the phosphor layer 3 in the arc tube 2 can be made to emit light effectively by the same operation as the second embodiment.

In general, the brightness of the lamp depends on the mercury vapor pressure in the arc tube, and the mercury vapor pressure depends on the temperature of the coolest part of the arc tube. When the temperature of the coldest part increases, the mercury vapor pressure exceeds the optimum value, and the brightness decreases.

According to the present embodiment, since the coldest part is filled with the heat conductive material 14, the heat conductive material 14 acts as a coolant, and the heat of the coldest part and the high frequency lighting circuit 10 and the like is removed. Good heat dissipation is possible. Therefore, it is possible to provide a lamp that does not lower the brightness and does not lower the efficiency. Further, when a silicone adhesive is used for the heat conductive substance 14, members on which the silicone adhesive acts can be fixed to each other.

In each of the above-described embodiments, the arc tube has been described as having a PS shape.

FIGS. 9 and 10 show the seventh and eighth embodiments. The basic configuration is the same as that of each of the above-described embodiments, and a detailed description thereof will be omitted.

In the seventh embodiment shown in FIG.
At the tip of the lead wire 5 inside, an electrode part 6 integrated with the lead wire 5
Are arranged respectively. The electrode portion 6 is configured so that the lead wires 5 are bent inwardly in a “<” shape so as to approach each other, and the interval between the electrodes is maintained at 15 mm or less. An end of the filament 7 is electrically connected to the vicinity of the electrode portion 6, and the filament 7 is substantially V
It has a U-shape or U-shape, and its lower end is fixed to the stem 4 by an anchor 20. The both ends of the filament 7 are connected by clamping the tip of the lead wire 5.

In the eighth embodiment shown in FIG. 10, the top of the arc tube 2 has a tapered shape, and an electrode portion 6 integral with the lead wire 5 is provided at the tip of the lead wire 5 in the arc tube 2. Each is arranged. The electrode portion 6 is configured so that the lead wire 5 is bent outward to maintain a distance of 15 mm or less from each other, and an end of the filament 7 is electrically connected to the vicinity of the electrode portion 6. . The filament 7 has a substantially inverted V-shape or an inverted U-shape as a whole and is formed so as to conform to the inner surface shape of the arc tube 2, and the top is supported by an anchor 20 having one end fixed to the stem 4. . In addition,
Both ends of the filament 7 are connected by clamping the tip of the lead wire 5.

Generally, in this kind of discharge lamp, the relationship between the interval between the electrodes and the lamp voltage is such that the lamp voltage in a region where the interval between the electrodes is small corresponds to the cathode drop voltage, and the interval between the electrodes is more than 10 mm. It is known that a sudden change in the lamp voltage corresponds to the anode drop voltage. Therefore, by setting the interval between the electrodes, that is, the interval between the cathode and the anode to 10 mm or less, the anode drop voltage becomes zero.
Thus, a discharge lamp is obtained in which the lamp voltage is equal to the cathode drop voltage and the discharge plasma is only negative glow.

In the seventh and eighth embodiments, the above is achieved by setting the distance between the electrode portions 6 to 15 mm or less. In this case, in order to increase the cold resistance of the filament 7 to 5Ω or more, the filament 7 is substantially The filament 7 is formed in a V-shape or an inverted V-shape to secure the length of the filament 7.

Next, the operation of the seventh and eighth embodiments will be described. When a voltage is applied from the lighting circuit 10 between the lead wires 5, a current flows through the filament 7 between the two electrodes 6, and the filament 7 emits thermoelectrons. When the temperature of the filament 7 becomes equal to or higher than a certain temperature, a current hardly flows through the filament 7 due to an increase in the resistance value, so that a negative glow is generated between the pair of electrode portions 6 to generate a glow discharge. In this case, since the filament 7 has a high cold resistance of 5Ω or more, the power loss due to the filament 7 is reduced, and the lighting efficiency is improved.

FIG. 11 shows a ninth embodiment, and a detailed description of the basic configuration is omitted. This embodiment is a discharge lamp suitable for a type of lighting with a DC power supply. In the case of lighting with a DC power supply, since the anode and the cathode of the electrodes are fixed, the positive ions of mercury sealed in the arc tube collect on the cathode, causing a bias phenomenon of mercury. Then, a bias of light emission occurs in which only the cathode of one electrode emits light strongly and the other anode does not emit light, which causes uneven light emission in the arc tube.

In this embodiment, the basic configuration is the same as that of the seventh embodiment shown in FIG.
In this embodiment, the cathode of the electrode section 6 is disposed substantially at the center of the arc tube 2. In other words, the cathode is located at the center, and the other anode is offset from the center. Here, reference numeral 10 denotes a DC power supply lighting circuit.

According to the present embodiment, it is possible to improve the uneven light emission of the arc tube 2.

Next, FIGS. 12 to 16 show tenth and eleventh embodiments. This embodiment is particularly different from the above-described embodiments in that an insulator is interposed between the electrodes.

In the tenth embodiment shown in FIGS. 12 to 14, FIG. 12 is a front view showing a cross section of a part of a fluorescent lamp, FIG. 13 is a side view thereof, and FIG. 14 is a schematic top view thereof. is there. First, the arc tube 2 has a cylindrical shape, and an insulator 25 made of mica or transparent glass is disposed substantially at the center between the electrode portions 6 in the arc tube 2. The insulator 25 is in the shape of a rectangular plate, and has a notch 25a that is elongated and cut at the center thereof. This notch 25a is made of an insulator 25
Functions as an escape for the filament 7 when the light emitting element is disposed in the arc tube 2. The insulator 25 is supported on the stem 4 by inserting the lower portion of the insulator 25 into the groove 4 a formed in the stem 4 and fixing the anchor 21 to the stem 4. In this embodiment, in order to increase the cold resistance of the filament 7, a core wire (main wire) is used as a coil axis.
, A so-called true triple coil is used.

In the eleventh embodiment shown in FIGS. 15 and 16, FIG. 15 is a front view showing a cross section of a part of a bulb-type fluorescent lamp, and FIG. 16 is a schematic top view thereof. The main difference from the above-described eleventh embodiment is that in the case where the electrode portions 6 are arranged in the long axis direction of the arc tube 2, a circular insulator 25 is arranged in the horizontal direction so as to be interposed between the electrode portions 6. It is a point that has been established. Here, the insulator 25 has an elongated notch 25b extending from the center to the outer periphery. The cutout hole 25b functions as a relief for the lead wire 5 and the filament 7 when the insulator 25 is provided. The insulator 25 is supported by the lead wire 5, and the support is achieved by clamping the bent portion 50 formed on the lead wire 5 and the anchor 22 fixed to the lead wire 5. As in the eleventh embodiment, a so-called true triple coil is used for the filament 7 to increase the cold resistance.

According to the tenth and eleventh embodiments, since the insulator 25 is interposed between the electrode portions 6, the discharge is bypassed as shown in the figure, the discharge path becomes longer, and the input power is increased. Thus, light emission due to arc discharge can be generated in addition to light emission due to negative glow. Therefore, it is possible to obtain a discharge lamp having a high total luminous flux.

[0089]

According to the discharge lamp of the present invention, since the filament for thermionic emission is provided between the electrodes even in a discharge lamp utilizing negative glow light emission, the number of parts is reduced and the lamp is turned on. The circuit does not need to provide a filament heating circuit separately from the discharging circuit, and the lighting circuit can have a simple configuration. In addition, since the cold resistance of the filament is high, power loss due to the filament is reduced,
Since the lighting efficiency is improved and the distance between the electrodes is in a positional relationship in which glow discharge is likely to occur, the discharge can be stabilized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bulb-type fluorescent lamp which is a first embodiment of a discharge lamp of the present invention.

FIG. 2 is a graph showing a relationship between a filament resistance value and a filament current.

FIG. 3 is a graph showing a relationship between a filament resistance value and luminous efficiency.

FIG. 4 is a sectional view of a bulb-type fluorescent lamp which is a second embodiment of the discharge lamp of the present invention.

FIG. 5 is a sectional view of a bulb-type fluorescent lamp which is a third embodiment of the discharge lamp of the present invention.

FIG. 6 is a sectional view of a bulb-type fluorescent lamp which is a fourth embodiment of the discharge lamp of the present invention.

FIG. 7 is a sectional view of a bulb-type fluorescent lamp which is a fifth embodiment of the discharge lamp of the present invention.

FIG. 8 is a sectional view of a bulb-type fluorescent lamp which is a sixth embodiment of the discharge lamp of the present invention.

FIG. 9 is a sectional view of a bulb-type fluorescent lamp which is a seventh embodiment of the discharge lamp of the present invention.

FIG. 10 is a sectional view of a bulb-type fluorescent lamp which is an eighth embodiment of the discharge lamp of the present invention.

FIG. 11 is a sectional view of a bulb-type fluorescent lamp which is a ninth embodiment of the discharge lamp of the present invention.

FIG. 12 is a sectional front view showing a bulb-type fluorescent lamp which is a tenth embodiment of the discharge lamp of the present invention.

FIG. 13 is a side view showing a light-bulb-shaped fluorescent lamp according to the tenth embodiment in section;

FIG. 14 is a top view showing a cross-section of a bulb-type fluorescent lamp according to the tenth embodiment.

FIG. 15 is a sectional front view showing a bulb-shaped fluorescent lamp which is an eleventh embodiment of the discharge lamp of the present invention.

FIG. 16 is a top view showing a cross-section of a light bulb shaped fluorescent lamp according to the eleventh embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge lamp, 2 ... Arc tube, 3 ... Phosphor layer, 5 ... Lead wire, 6 ... Electrode, 7 ... Filament.

Claims (8)

[Claims] An arc tube in which a discharge medium is sealed; a pair of lead wires introduced into the arc tube; and at least one pair of wires arranged in a positional relationship such that a negative glow discharge can be generated in the lead wires. An electrode; a cold resistance of not less than 5Ω, both ends of which are electrically connected to a lead wire near the pair of electrodes and coated with an emitter, and a distance between the electrodes of 5 mm or more and 50 m
m or less filaments. 2. The discharge lamp according to claim 1, wherein the discharge medium is made of at least one of Ne, Ar, Kr, and Xe. 3. The discharge medium comprises mercury and a rare gas,
3. The discharge lamp according to claim 1, wherein a phosphor layer is formed on the arc tube. 4. The discharge lamp according to claim 1, further comprising a cover for supporting the arc tube, and a lighting circuit disposed in the cover or the base. 5. The discharge lamp according to claim 1, wherein the pair of electrodes are disposed in a longitudinal direction of the arc tube. 6. A cover for supporting the arc tube; and a base; a coolest part of the arc tube being introduced into the cover or the base, and a heat conductive material being disposed in contact with the introduction part. The discharge lamp according to any one of claims 1 to 5, wherein: 7. A lamp which is lit by a DC power supply and includes a pair of electrodes.
The discharge lamp according to any one of claims 1 to 6, wherein the cathode portion is disposed substantially at the center of the arc tube. 8. The discharge lamp according to claim 1, wherein an insulator is interposed between the pair of electrodes.