JPH02227955A - Low pressure mercury vapor filled electric discharge lamp - Google Patents

Abstract

PURPOSE:To control change in luminous length by connecting an end section close to the bulb end section of a filament arranged at one end side of the bulb with a power supply side, and thereby concurrently connecting an end remotely apart from the bulb end section arranged on the other end of the bulb with the power supply side. CONSTITUTION:A filament 3a arranged at the upper end section of a bulb 2 is connected with a power supply 7 side at a coil end 4b close to the sealing cut section of the bulb 2, and a filament 3b arranged at the lower end section of the bulb 2 is connected with the power supply 7 side at a coil end 5a apart from the sealing cut section of the bulb 2. Cathode spots are formed at high voltage points of the filaments 3a and 3b, that is, at the end sections A and A close to the power supply 7 at the early stage of their lives, and the cathode spots A and A are moved to the end section side which goes away from the power supply 7 as their lives expire, because electron emitting substances vanish, they are moved to spots B and B respectively at the final stage of their lives, and a positive column is moved roughly in parallel so that the length of the positive column is scaresely changed. This constitution can thereby maintain the positive column to be roughly same in length.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a low-pressure mercury vapor in which the axial direction of the coil filament sealed at both ends of the bulb is arranged substantially along the axial direction of the bulb. Regarding discharge lamps.

(Prior Art) A low-pressure mercury vapor discharge lamp, such as a fluorescent lamp lit with a single choke coil type ballast, has a lighting circuit configuration shown in FIG. 3 or 4.

That is, in FIGS. 3 and 4, l is a fluorescent lamp, and hot cathodes, that is, coil filaments 3a and 3b, are sealed at both ends of the bulb 2, respectively. Both ends of these filaments 3a, 9b are lead wires 4a,
4b, 5a, 5b, and these lead wires 4a
, 4b, 5a, and 5b are led out from the end of the valve 2 and connected to a bottle of a cap (not shown).

Such a fluorescent lamp l is connected to a lighting circuit and lit. In other words, 6 is a single choke coil type ballast,
7 is a power source.

Coil filament 3a of the fluorescent lamp l.

3b is such that one end thereof is connected to the power source 7, and in this case, one coil filament, for example 3a, is connected in series with the ballast B.

Further, the other ends of each of the coil filaments 3a and 3b are connected to a starting circuit 8. The starting circuit 8 consists of a circuit in which a lighting tube 9 and a capacitor lO are connected in parallel, and by connecting both ends of this circuit 8 to the other ends of the coil filaments 3a and 3b, this starting circuit 8 can be used as a fluorescent lamp. It will be connected in parallel to l.

In such a circuit structure, the bimetallic switch in the lighting tube 9 is closed before the fluorescent lamp 1 starts, and when the power switch is turned on and current flows from the power source 7 to the coil filaments 3a and 3b, As the coil filaments 3a and 3b begin to heat up, current flows to the lighting tube 9 and capacitor 10 of the starting circuit 8, and the lighting tube 9
The bimetal switch inside starts to generate heat. As the temperature rises, the filaments 3a and 3b begin to emit thermoelectrons, and when the bimetal switch in the lighting tube 9 is opened in accordance with this timing, the voltage stored in the capacitor 10 is applied to the filaments 3as and 3b. As a result, a glow discharge is started between the filaments 3a and 3b.

Therefore, the mercury sealed in the bulb 2 is evaporated and the mercury emits ultraviolet light, which excites the phosphor coating 11 (shown in FIG. 2) formed on the inner surface of the bulb l. It emits visible light.

While such a lamp is lit, the coil filament 3a,
Since a discharge current flows between 3b and 3b, no current flows through the starting circuit 8, and therefore the lighting tube 9 does not operate.

Furthermore, even if voltage fluctuations occur on the power source 7 side during such lighting, the fluctuations are absorbed by the ballast 6 to maintain stable discharge.

Incidentally, recent fluorescent lamps are increasingly being used as light sources for various devices and fields, such as backlights for liquid crystal displays and instrument panels. It is required to reduce the diameter.

For this reason, the coil filaments 3a and 8b sealed at the end of the bulb are changed from a horizontal suspension structure in which the coil axis of the filament 3a is along the radial direction of the bulb 2 to a structure in which the coil axis of the filament 3a is along the radial direction of the bulb 2, as shown in FIG. A structure is adopted in which the structure is changed to a vertical suspension structure along the two axial directions. The coil axis of the filament 3a is aligned in the axial direction of the bulb 2,
Alternatively, by arranging it in substantially the same direction as this direction, the diameter of the valve 2 can be made smaller.

In addition, in FIG. 2, 12 is the previously explained phosphor coating, 1
3 is a button stem.

(Issue m to be solved by the invention) However, as shown in FIG.
When a vertical suspension structure is adopted in which the coil axis of the valve 2 is arranged along the axial direction of the valve 2, the following problems occur.

That is, during lighting, the filament impedance inside the fluorescent lamp l is higher than the impedance of the discharge space, and therefore, at the beginning of its life, the impedance of the filaments 3a and 8b is lower, that is, the location where the voltage is higher, or in other words, Cathode spots are formed at the end near the power source 7, and discharge occurs between these cathode spots.

Such a cathode spot has the property of gradually moving toward the end portion away from the power source 7 as the electron emitting substance disappears over the life of the cathode spot.

In the case of the conventional circuit structure shown in FIG. 3, each of the vertically suspended filaments 3a and 3b is connected to the end of the discharge space (positive column side), that is, to the end of the coil remote from the sealed end of the bulb 2. The lead wires 4a and 5a are connected to the power source 7 side, and the filament 3a.

Lead wires 4b and 5b are connected to the end of the bulb 3b far from the discharge space side (positive column side), that is, to the end of the coil near the sealed end of the bulb 2, and are connected to the starting circuit.

Therefore, at the beginning of the life, cathode spots are formed at the ends ASA of each filament 3a, 3b on the discharge space side (positive column side), and a positive column is generated between these cathode spots. As the life progresses, such a cathode spot gradually moves to the bulb end side B, B, and a positive column is generated between these B, 8.

That is, as the life passes, the length of the positive column changes to L, causing a problem that the length of light emission gradually increases.

On the other hand, in the case of the conventional circuit structure shown in FIG. The lead wires 4a, 5a connected to are connected to the starting circuit, and are connected to the ends of the filaments 3a, 3b far from the discharge space side (positive column side), that is, the coil ends near the sealed end of the bulb 2. lead wire 4b,
5b is connected to the power source 7 side.

Therefore, at the beginning of the life, cathode spots are formed on the bulb end sides A and A of each filament 3a and 3b, respectively, and a positive column is generated between these cathode spots. and,
As the life progresses, such a cathode spot gradually moves to the discharge space side (positive column side) BsB, and a positive column is generated between these B and 8.

That is, in this case as well, the length of the positive column changes to L- as the life passes, and in this case, a problem arises in that the length of light emission gradually becomes shorter.

The present invention was made based on the above-mentioned circumstances, and is a low-pressure mercury vapor in which the length of the positive column does not change significantly even if the cathode spot moves with the passage of life, that is, the length of light emission hardly changes. The aim is to provide a discharge lamp.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, the filament disposed at one end of the bulb has its end close to the bulb end connected to the power supply side, and the filament disposed at the other end of the bulb. The filament disposed on the side has a circuit configuration such that the end farthest from the bulb end is connected to the power supply side.

(Function) According to the present invention, at the beginning of the life of the filament, a cathode spot is formed at the end of the filament placed at one end of the bulb, and a cathode spot is formed at the end of the filament placed at the other end of the bulb. A cathode spot is formed at the end of the filament far from the bulb end, and as the life progresses, these cathode spots move almost in parallel, so the length of the positive column does not change significantly, that is, the emission length can be maintained at approximately the same length.

(Example) The present invention will be described below based on an example shown in FIG.

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and the same members as in FIGS. 3 and 4 are given the same numbers.
1 is a fluorescent lamp, 2 is a bulb, 3a and 3b are hot cathodes, that is, coil filaments, 4a and 4b,
5a and 5b are lead wires.

Further, 6 is a single choke coil type ballast, 7 is a power source, 8 is a starting circuit, 9 is a lighting tube, and 10 is a capacitor.

As shown in FIG.
The filament 3a has a vertical suspension structure along the axial direction of the filament 3a.
The diameter of the valve 2 can be reduced by arranging the coil axis along the axial direction of the valve 2 or in substantially the same direction as this direction.

In this embodiment, the filament 3a placed at one end of the bulb 2, for example, the upper end, is placed at the end of the discharge space (positive column side), that is, the end of the coil remote from the sealed end of the bulb 2. The connected lead wire 4a is connected to the starting circuit 8, and the discharge space side (
A lead wire 4b connected to the end farthest from the positive column side, that is, the end of the coil near the sealed end of the bulb 2, is connected to the power source 7 side.

On the other hand, the filament 3b disposed at the other end of the bulb 2, for example, the lower end, is connected to the end on the discharge space side (positive column side), that is, the coil end that is away from the sealed end of the bulb 2. The lead wire 5a is connected to the power source 7 side, and the lead wire 5b is connected to the end of the filament 3b far from the discharge space side (positive column side), that is, the end of the coil near the sealed end of the bulb 2. is connected to the starting circuit 8.

In such a configuration, the filament impedance is larger than the impedance of the discharge space during lighting, and therefore, at the beginning of the life, the filament Ba, 3b
A cathode spot is formed at the lower impedance, that is, at a higher voltage location, or in other words, at the ends A, A closer to the power source 7.

In the case of this embodiment, one filament 3a has a valve 2
A cathode spot A is formed at the end of the coil near the sealed end of the filament 3b, and a cathode spot A is formed on the discharge space side (positive column side) on the other filament 3b.
A cathode spot A is formed at the end.

Therefore, a discharge occurs between these cathode spots A and A, and a long positive column is generated.

Since the electron-emitting substance disappears, these cathode spots A, A gradually move toward the end portions away from the power source 7 as the lifespan progresses, that is, they move to B, B, respectively, at the end of the lifespan.

In this case, in one filament 3a, on the discharge space side,
In addition, the other filament 3b moves toward the sealed end of the bulb 2, that is, the positive column moves almost in parallel, and therefore the length L of the positive column hardly changes.

Therefore, problems such as the light emission length changing with the passage of life are eliminated, and changes in light emission characteristics are reduced.

Note that the present invention is not limited to the above embodiments.

In other words, the single choke coil ballast 6 is used as the lighting circuit.
The present invention is not limited to those using a high-frequency lighting circuit, and may be, for example, a high-frequency lighting circuit.

Further, the fluorescent lamp is not limited to a straight tube type, but may have a curved discharge space.

The coil filament may also be arranged obliquely to the valve axis.

Furthermore, when selecting the connection of the electrode lead wire, if the lamp and lighting circuit are separate, it is sufficient to specify the connection direction, and if the lamp and lighting circuit are integrated in advance, it is sufficient to specify the connection direction at the time of assembly. Just make the connection.

[Effects of the Invention] As explained above, according to the present invention, at the beginning of the life of the bulb, a cathode spot is formed at the end of the filament placed at one end of the bulb, which is close to the bulb end side, and at the other end of the bulb. A cathode spot is formed at the end of the filament located far from the bulb end, and as the life progresses, these cathode spots move almost in parallel, so the length of the positive column changes significantly. In other words, the emission length can be maintained at approximately the same length.

Therefore, fluctuations in light emission characteristics are reduced.

[Brief explanation of the drawing]

Fig. 1 is a lighting circuit configuration diagram of a fluorescent lamp showing an embodiment of the present invention, Fig. 2 is a sectional view of one end of the lamp showing the structure of the filament installation, and Figs. It is a block diagram which shows the lighting circuit of a light lamp. 1... Fluorescent lamp, 2... Bulb, 3a, 3b.
・・Coil filament, 4a, 4b, 5a, 5b・
...Lead wire, B...Single tee yoke coil type ballast,
7...Power supply, 8...Starting circuit, 9...Lighting tube, l
O... Capacitor. Figure 1 Figure 2 Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A coil filament is sealed at both ends of the bulb,
In a low-pressure mercury vapor discharge lamp in which the coil axis direction of these filaments is arranged approximately along the bulb axis direction, and one end of each of these filaments is connected to the power supply side and the other end is connected to the starting circuit, one end of the above-mentioned bulb is used. The end of the filament placed on the side of the bulb is connected to the power source, and the end of the filament placed on the other end of the bulb is connected to the power source. A low-pressure mercury vapor discharge lamp characterized by having a circuit configured as follows.