JPH09148075A - Low pressure discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long lifetime and eliminate directionality in connection to a lighting circuit. SOLUTION: A discharge lamp concerned has a photo-transmissive bulb 2 which is fitted at the end with a base metal 1 and equipped with an electrode 4 where a main electrode 4a and another electrode 4b for starting are connected in series, wherein the main electrode 4a carries an electron emitting substance and works for the whole lighting lifetime given while the other electrode 4b has a low thermal capacity, carries an electron emitting substance, and is fed with current at starting and heated for the start of the discharge. The base metal is furnished internally with a rectifier bridge 8 which is connected with the two ends of the electrode 4 and controls the current direction flowing through the electrode 4 from the side with the starting electrode 4b toward the main electrode 4a.

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.

[0002]

5 to 9 show a conventional low-pressure discharge lamp. This low-pressure discharge lamp is a straight tube type fluorescent lamp, and a base 1 is provided at both ends thereof. An electron emissive material is applied to both inner ends of a light-transmissive bulb 2 in which a discharge gas containing a gas or an argon gas is sealed and activated, and at the same time, an electrode 4 supported by a pair of lead wires 3 is attached. It is equipped with.

Generally, in order to light a fluorescent lamp, which is a low-pressure discharge lamp, a current limiting element called a ballast is required because of its discharge characteristics. Therefore, when the low-pressure discharge lamp configured as described above is lit at a low frequency such as a commercial frequency, a choke coil 5a is used as the ballast 5 as shown in FIG. A starting switch 6 called a glow starter is used to start the lamp La.

Then, with the starting switch 6 closed, a current of about 1.5 times the discharge current is passed through the electrode 4 to cause the electrode 4 to move.
Is sufficiently heated, and then the starting switch 6 is opened, so that the kick voltage generated at both ends of the choke coil 5a, which is the ballast 5, is applied to the fluorescent lamp L.
The fluorescent lamp La is started by applying it to both ends of a. When a glow starter is used as the starting switch 6, when the power supply AC is turned on, a preheating current flows through the electrode 4 to sufficiently heat the electrode 4 to emit thermoelectrons, and as shown in FIG. Thus, the discharge A is generated at both ends of the electrode 4, and the fluorescent lamp La starts in about 1 to 2 seconds.

In recent years, an electronic switch has been used instead of the glow starter as the starting switch 6. The electronic starter switch 6 called the electronic starter has a preheating time controlled, so that the glow starter flashes tens of thousands of times to cause a lamp failure, while the electronic starter has hundreds of thousands of times. Blinking is possible, and the blinking life can be extended. When this electronic starter is used, the time required to start the fluorescent lamp La is about 0.8 seconds.

As a ballast, a high-frequency lighting device called an electronic ballast or an inverter ballast has been used for the purpose of improving efficiency. There are various circuit systems for this high-frequency lighting device,
For the purpose of simplifying the circuit and the like, a circuit type high frequency lighting device 5b in which a capacitor C is connected between one ends of opposing electrodes 4 as shown in FIG. 8 has become widespread.

High frequency lighting device 5b of this type of circuit system
Rectifies and smoothes the AC power supply AC and converts it into a high frequency to start and light the fluorescent lamp La. The high frequency lighting device 5b includes a control unit (not shown), and the control unit At the time of starting, the voltage applied to both ends of the fluorescent lamp La is lowered to such an extent that the lamp does not start to heat the electrode 4, and then the voltage is increased to several hundreds of volts to start the fluorescent lamp La. There are those that do not include a control unit in order to further simplify the circuit. In the high-frequency lighting device 5b having no control unit, a voltage of several hundreds of volts is applied between the electrodes 4 at both ends of the fluorescent lamp La and at the same time the electrode 4 is preheated as soon as the power supply AC is turned on. A current flows and the fluorescent lamp La starts in about 0.3 seconds.

That is, in this type of circuit type high frequency lighting device 5b, a voltage of several hundred volts is applied between both ends of the fluorescent lamp La at the same time when the power source AC is turned on, and the voltage causes a voltage of several hundred volts to be generated in the vicinity of the electrode 4. As shown in FIG. 9, a discharge (plasma) B different from the thermoelectron discharge in the case of using the glow starter is generated, and the fluorescent lamp La is started. It is presumed that this discharge was not caused by thermoelectrons as in the case of using a glow starter, but was caused by the voltage applied across the fluorescent lamp La.

[0009]

However, in the conventional low-pressure discharge lamp configured as described above, there is a case where the lamp is lit by the high-frequency lighting device 5b which does not have a control unit for controlling the preheating time. The fluorescent lamp lights up for about 0.3 seconds in a short time which is not sufficient to heat the electrode 4 sufficiently, and since plasma exists in the vicinity of the electrode 4, the electrode 4 should normally be turned on. Most of the preheating current that flows and heats the electrode 4 also flows through the plasma and the electrode 4
However, there is a problem that the heating becomes insufficient and the ion bombardment increases, and the blinking life of the lamp is shortened.

Therefore, the inventors of the present invention have shown in FIGS.
As shown in FIG. 1, a main electrode 4a that carries an electron emissive substance and has a long lighting life, and a main electrode 4a that carries an electron emissive substance and is energized and heated at the time of startup to reach a sufficient temperature before the main electrode 4a to start discharge. Low heat capacity starting electrode 4
The low-pressure discharge lamp provided with the electrode 4 in which b and b are connected in series was previously proposed. This low-pressure discharge lamp is a fluorescent lamp, and as shown in FIG. 11 (a), it is started by the starting electrode 4b having a small heat capacity at the time of starting, and thereafter, as shown in FIG. 11 (b), the emission point E Is moved to the main electrode 4a side.

However, when this low-pressure discharge lamp is connected to a lighting circuit equipped with a ballast as shown in FIGS. 12 and 13 and is lit, the lamp (discharge) current is such that the resistance of the electrode 4 becomes the smallest. Since the flow tends to flow, the emission point E is still present on the starting electrode 4b even after lighting. The starting electrode 4b is designed to have a small heat capacity so that the temperature rises sufficiently in a short time, and when the lamp current flows for a long time, the temperature becomes too high and the wire is immediately disconnected. There is also a problem that it is necessary to pay attention to the direction in which the electrode 4 is connected.

Further, in order to eliminate this directivity, the inventors of the present application connected one main electrode 4a in series to both ends of the starting electrode 4b as shown in FIG. 14, that is, the starting electrode 4a. A low-pressure discharge lamp provided with an electrode 4 in which 4b is sandwiched between main electrodes 4a was also previously proposed. In this low-pressure discharge lamp, the stems 7 arranged at both ends of the bulb 2 are provided with six introduction wires 3. Since the provided stem 7 is required, it tends to be difficult to manufacture the stem 7 and attach the electrode 4.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a low-pressure discharge lamp having a long life and no directivity of connection to a lighting circuit.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to the invention as set forth in claim 1, in which an electron emissivity is provided inside a translucent bulb 2 having a base 1 at its end. A low voltage having an electrode 4 in which a main electrode 4a carrying a substance and having a long lighting life and a starting electrode 4b carrying an electron emissive substance and having a low heat capacity, which is electrically heated at the time of starting and starts discharging, are connected in series. A discharge lamp, characterized in that rectifying bridges 8 for restricting a direction of a current flowing through the electrodes 4 from the starting electrode 4b side to the main electrode 4a side are connected to both ends of the electrode 4. Is.

According to a second aspect of the invention, in the low pressure discharge lamp of the first aspect, the rectifying bridge 8 is provided.
Is provided inside the base 1.

Further, in the invention according to claim 3, in the low-pressure discharge lamp according to claim 1 or 2, one end is near the starting electrode 4b, and the one end is the rectifying bridge 8
And an auxiliary anode 4c connected between the starting electrode 4b and the starting electrode 4b.

Further, the invention according to claim 4 is characterized in that, in the low-pressure discharge lamp according to claim 3, the auxiliary anode 4c is disposed on the front side of the starting electrode 4b. It is a thing.

[0018]

1 to 3 show a first embodiment of a low-pressure discharge lamp of the present invention. This low-pressure discharge lamp is, for example, a straight tube type fluorescent lamp for 20 W. It mainly comprises a valve 2 having a base 1 at both ends, an electrode 4 which is activated by applying an electron emissive material, and a rectifying bridge 8.

The bulb 2 is made of a light-transmissive material such as glass and is formed into a substantially cylindrical shape. Stems 7 are provided at both ends to hermetically seal the bulb 2 and a phosphor is applied to the inner wall of the bulb 2. . Further, a base 1 having a pair of lamp pins 1a is provided at both ends of the bulb 2, and an airtight space formed inside the bulb 2 is filled with a discharge gas containing mercury gas or argon gas. There is.

The electrode 4 carries an electron emissive substance and has a long lighting life, and the electrode 4 carries an electron emissive substance and is electrically heated at the time of starting to reach a sufficient temperature before the main electrode 4a to be discharged. It has a low heat capacity starting electrode 4b for starting. The main electrode 4a and the starting electrode 4b are connected to the lead wire 3 provided through the stem 7 that seals both ends of the valve 2 at both ends and held, and are connected to the main electrode 4a. One of the lead wires 3 and one connected to the starting electrode 4b are connected in the base 1, and the main electrode 4a and the starting electrode 4b are connected in series to form the electrode 4.

The rectifying bridge 8 is a rectifying circuit formed by connecting four diodes to regulate the direction of the current flowing through the electrode 4 in one direction, and its input ends a and b are connected to the lamp pin 1a. And the output terminals c and d
Is connected to both ends of the electrode 4 via the lead-in wire 3, and the rectifying bridge 8 is housed inside the base 1. That is, the rectifying bridge 8 is formed in a loop shape by connecting the first series part in which the anodes of the two diodes are connected and the second series part in which the cathodes of the two diodes are connected at both ends, Both ends are input ends a and b
And connected to the lamp pin 1a respectively,
The respective midpoints c and d of the first series part and the second series part are output ends, and one output end c is connected to the other lead-in wire 3 of the main electrode 4a which is one end of the electrode 4. The other output end d is connected to the other lead-in wire 3 of the starting electrode 4b which is the other end of the electrode 4. The four diodes here are Schottky barrier diodes (sc802
-04) was used.

In the low-pressure discharge lamp having such a structure, whichever direction the lamp pin 1a is connected to the lighting circuit, the preheating current flowing through the electrode 4 at the time of starting is regulated by the rectifying bridge 8 and started. It flows from the working electrode 4b side to the main electrode 4a side.

With such a configuration, in the low pressure discharge lamp according to the present embodiment, no matter which direction the lamp pin 1a is connected to the lighting circuit, the current flowing through the electrode 4 is rectified by the rectifying bridge 8. It is regulated and flows from the starting electrode 4b toward the main electrode 4a. At the time of starting, a preheating current flows through the electrode 4 to heat the electrode 4, the starting electrode 4b having a low heat capacity reaches a sufficient temperature before the main electrode 4a, and an emission point is formed there to easily start the electrode. Therefore, the discharge lamp has a long life, and after starting, the lamp (discharge) current of the discharge lamp tries to flow so that the resistance of the electrode 4 becomes the smallest, so that the emission point is on the power supply side of the main electrode 4a. Will be formed. Then, as shown in FIG. 2 and FIG. 3, in the cathode cycle, electrons e are emitted from the emission point E of the main electrode 4a, so that the current flows in the opposite direction, and the discharge current almost flows through the starting electrode 4b. Without flowing,
Also in the anode cycle, the electron e is emitted from the starting electrode 4
The discharge current hardly reaches the power source side of b and flows through the starting electrode 4b. Therefore, the connection of the electrode 4 to the lighting circuit of the discharge lamp has no directivity, and an excessive current does not flow to the starting electrode 4b having a low heat capacity, which reduces the risk of disconnection, resulting in a long service life and the electrode. It is sufficient to provide at most four lead-in wires 3 for supporting 4, so that it is easy to manufacture. Furthermore, since the rectifying bridge 8 is provided inside the base 1, the rectifying bridge 8 does not block the light emitted from the bulb 2.

FIG. 2 shows a second embodiment of the low-pressure discharge lamp of the present invention. The difference from the first embodiment is that it is near the starting electrode 4b, that is, on the front side. An auxiliary anode 4c made of a nickel wire having a diameter of 1 mm and a length of 10 mm is provided on the opposing electrode 4 side which is the discharge path side of the starting electrode 4b, and one end of which is a rectifying bridge 8 and the starting electrode 4b.
The third embodiment is similar to the first embodiment except that it is connected between the two.

Even with this structure, the same effects as those of the first embodiment can be obtained, and in the anode cycle,
Since the electrons e emitted from the emission point E of the cathode and reaching the anode are unlikely to be in the form of spots, the discharge current flowing out from the starting electrode 4b is also not in the form of spots. Is the starting electrode 4
There is a risk that the starting electrode 4b will be heated by flowing through b, but the provision of the auxiliary anode 4c increases the area of the anode and reduces the current density of the discharge current flowing into the starting electrode 4b. The electrode 4b is less likely to be overheated,
The risk of disconnection of the electrode 4 is further reduced, and the life can be further extended.

In the present embodiment, the auxiliary anode 4c is made of nickel wire, but the present invention is not limited to this, and any metal can be used as long as it does not react with mercury gas to form amalgam. Also, the shape and dimensions are not limited to those exemplified in this embodiment.

In each of the above embodiments, the rectifying bridge 8 is housed inside the base 1, but the present invention is not limited to this, and the rectifying bridge 8 may be built in near both ends of the valve 2. It can be anything.

[0028]

As described above, according to the present invention, no matter which direction the lamp pin is connected to the lighting circuit, the current flowing through the electrode is regulated by the rectifying bridge. It flows from the starting electrode toward the main electrode.
At the time of starting, the electrode is preheated, the starting electrode having a low heat capacity reaches a sufficient temperature before the main electrode, and the emission point is formed there to start easily, so that the discharge lamp has a long life. Become. Further, after starting, the discharge current tries to flow so that the resistance of the electrode becomes the smallest, so that an emission point is formed on the power supply side of the main electrode. And, in the cathode cycle, since electrons are emitted from the emission point of the main electrode,
The current flows in the opposite direction, the discharge current hardly flows through the starting electrode, and even in the anode cycle, the electrons reach the power supply side of the starting electrode and the discharge current almost flows through the starting electrode. There is no. Therefore, there is no directivity in connecting the electrodes to the lighting circuit of the discharge lamp, and an excessive current does not flow to the starting electrode having a low heat capacity, so that there is no fear of disconnection and a longer life can be achieved.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effects of the invention described, since the rectifying bridge is provided inside the base, the rectifying bridge does not block the light emitted from the bulb.

In addition to the effect of the invention described in claim 1 or 2, in the inventions of claim 3 and claim 4, in the anode cycle, it is emitted from the emission point of the cathode to the anode. Since the arriving electrons are unlikely to be in a spot shape, the discharge current flowing out from the starting electrode does not have a spot shape either, and if the discharge current is large, part of it will flow through the starting electrode and the starting electrode will heat up. However, by providing the auxiliary anode, the area of the anode is increased, the current density of the discharge current flowing into the starting electrode is reduced, and the starting electrode is less likely to be overheated. There is less fear and the life can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a main part of a low pressure discharge lamp according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the cathode cycle of the above.

FIG. 3 is a schematic diagram illustrating an anode cycle of the above.

4A and 4B show a main part of a low pressure discharge lamp according to a second embodiment of the present invention, wherein FIG. 4A is a schematic view of a connection state of electrodes, and FIG. 4B is a perspective view of the electrodes.

FIG. 5 is a perspective view showing a main part of a conventional low pressure discharge lamp.

FIG. 6 is a lighting circuit diagram of the above.

FIG. 7 is a perspective view for explaining a starting state by the above lighting circuit.

FIG. 8 is another lighting circuit diagram of the above.

FIG. 9 is a perspective view for explaining a starting state by the above lighting circuit.

FIG. 10 is a lighting circuit diagram of a low-pressure discharge lamp previously proposed by the inventors of the present application.

11A and 11B show the states of the above electrodes, FIG. 11A is a schematic diagram at the time of starting, and FIG. 11B is a schematic diagram after lighting.

FIG. 12 is a circuit diagram in which the low-pressure discharge lamp of the above is incorrectly connected.

FIG. 13 is a schematic view showing a state of the above electrode.

14A and 14B show different electrodes of the low-pressure discharge lamp previously proposed by the inventors of the present application, in which FIG. 14A is a schematic view of a connected state of the electrodes, and FIG. 14B is a perspective view of the electrodes.

[Explanation of symbols]

 1 Base 2 Valve 4 Electrode 4a Main Electrode 4b Starting Electrode 4c Auxiliary Anode 8 Rectifying Bridge

Claims (4)

[Claims] 1. A light-transmitting bulb having a base at its end, which carries an electron emissive material and carries an electron emissive material to maintain a lighting life, and an electron emissive material, and at the same time, is electrically heated to start discharging. A low-pressure discharge lamp having an electrode in which a starting electrode having a low heat capacity is connected in series,
A low-pressure discharge lamp, characterized in that a rectifying bridge is connected to both ends of the electrode so as to restrict the direction of a current flowing through the electrode from the starting electrode side toward the main electrode side. 2. The low-pressure discharge lamp according to claim 1, wherein the rectifying bridge is provided inside the base. 3. The low-voltage discharge according to claim 1, wherein an auxiliary anode having one end connected between the rectifying bridge and the starting electrode is provided in the vicinity of the starting electrode. Electric light. 4. The low-pressure discharge lamp according to claim 3, wherein the auxiliary anode is arranged on the front side of the starting electrode.