JPH0524116Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technique for improving the starting performance of a discharge lamp equipped with a non-preheating internal discharge electrode.

[Prior art]

A discharge lamp equipped with a preheating type internal electrode emits thermionic electrons by sufficiently preheating the discharge electrode made of a filament to a high temperature before starting the discharge lamp, and these thermionic electrons immediately activate the cathode spot. form and start the discharge lamp. On the other hand, in a discharge lamp equipped with a non-preheating internal discharge electrode, a cathode spot must be formed through the gamma effect, in which the electric field between the discharge electrodes causes cations to collide with the cathode and emit secondary electrons. Does not fall apart. Therefore, in order to start a discharge in a discharge lamp having such a non-preheated internal discharge electrode, electrons and ions ionized by external light irradiation, ultraviolet rays, or even natural radiation must be ionized by an electric field. This requires accelerating it and colliding it with gas atoms to create an avalanche of electrons. For this reason, in the dark, the generation of photoelectrons caused by the photoelectric effect of the electrode due to external light is cut off, so there is a shortage of initial electrons necessary to generate an electron avalanche, and the formation of a cathode spot due to the γ effect, that is, an abnormal glow discharge or an arc. The so-called dark effect, in which the start of a steady discharge such as a discharge is delayed, becomes a problem. In particular, in order to eliminate the temperature dependence of the starting voltage caused by the temperature dependence of mercury vapor pressure, a non-preheating discharge lamp is filled with an inert gas such as xenon at a relatively high pressure without containing mercury vapor. In this case, the high pressure of the filled gas increases the number of times that electrons collide elastically with gas atoms, reducing the ability to generate the electron avalanche, so the dark effect becomes even more pronounced.

Conventionally, to deal with such dark effects, ⁶⁰ Co, ²³⁸ U,
Radioactive isotopes such as ⁶³ Ni and ¹⁴⁷ Pm are applied to the inner wall of the bulb, and the relatively large ionizing effect of the β rays constantly emitted from such radioactive isotopes generates the ions and ions required when starting the discharge lamp. It is possible to encourage the generation of electrons within the bulb, thereby generating enough initial electrons necessary to start the discharge, or to place a light emitting element outside the bulb to emit light to the discharge electrode. As a result, measures were taken to forcibly generate photoelectrons by the photoelectric effect of the discharge electrode even in the dark.

[The problem that the idea aims to solve]

However, when radioactive isotopes are used, the effects on the human body and the natural environment cannot be ignored when the discharge lamp is destroyed or disposed of, and for this reason, new and safe measures have been desired. Further, in a structure in which the light emitting element is arranged outside the bulb, a structure for attaching the light emitting element to the outside of the bulb and a new manufacturing process are required, and furthermore, the discharge lamp becomes larger by the amount of the light emitting element.

An object of the present invention is to provide a discharge lamp that can prevent starting delays and uneven starting characteristics due to darkness effects without using radioactive isotopes or external light emitting elements.

[Means to solve the problem]

As a means to solve the above-mentioned problems, the discharge lamp of the present invention includes a non-preheated internal discharge electrode sealed inside a bulb having a fluorescent coating on the inner surface and filled with inert gas. A structure is adopted in which a light emitting filament is placed near the internal discharge electrode and electrically insulated from the internal discharge electrode.

Forming the light emitting filament into a coil shape,
The inside of the coil can be filled with an electron emitting material.

[Effect]

According to the above-mentioned means, the light-emitting filament, which is energized to start the discharge lamp, irradiates light to the internal discharge electrode located near it, and this light generates photoelectrons due to the photoelectric effect of the internal discharge electrode. do.
The photoelectrons generated in this way act as initial electrons to generate an avalanche of electrons required to start a discharge, even in the dark, and quickly generate an abnormal glow discharge or arc discharge through the γ action. By starting a sustained discharge, it is possible to prevent delays in starting and uneven starting characteristics due to dark effects without using radioactive isotopes or external light emitting elements.

At this time, since the light-emitting filament is electrically insulated from the internal discharge electrode, in other words, the internal lead-in wires between the internal discharge electrode and the light-emitting filament are individualized, so the light-emitting filament is The lighting closed circuit and the discharge driving closed circuit including the internal discharge electrode can be configured as separate closed circuits. This works to form an electric field between the light-emitting filament and the internal discharge electrode in its vicinity during the lighting operation of the discharge lamp, and this electric field also accelerates the initial electrons, causing the cathode spot to rise due to the γ action. Accelerates formation.

In addition, the fact that the closed circuit for lighting and the closed circuit for driving discharge can be configured separately means that the current and voltage applied to the light emitting filament can be controlled below the rated value, regardless of the discharge power for the internal discharge electrode. This contributes to extending the life of the light-emitting filament.
In addition, the light-emitting filament does not need to function as an internal discharge electrode during sustained discharge.
At this time, the light emitting filament receives less electron impact than the internal discharge electrode. These things ensure a long service life for light-emitting filaments when a non-preheated internal discharge electrode that does not use a filament is employed.

When the coil of the above-mentioned light-emitting filament is filled with an electron-emitting substance, electrons are efficiently emitted from the electron-emitting substance due to the heat generated when the light-emitting filament is energized, and these emitted electrons have a γ effect similar to the above-mentioned photoelectrons. It promotes the production of cations for the purpose of oxidation, and acts to form cathode spots more quickly even in the dark. Since such an electron-emitting material is provided in a light-emitting filament that is not used as a substantial discharge electrode as described above, the electron impact during sustained discharge is reduced, and the electron-emitting material is Disintegration rate is reduced.

〔Example〕

1A and 1B are a partially longitudinal plan view and a partially longitudinal front view of a discharge lamp which is an embodiment of the present invention.

The discharge lamp shown in Fig. 1 has a power consumption of more than 10 watts, a total length of 500 mm or less, and is not particularly limited.
The inner diameter of the bulb is less than 10 mm, and it is applied to exposure lamps for electronic copying machines and image reading lamps for facsimile machines. A fluorescent coating 2 is formed on the inner surface of a glass bulb 1 in this discharge lamp. Both ends of the valve 1 are sealed by a pair of stem parts 3A, 3B, a pair of lead-in wires 4A, 4B are sealed to one stem part 3A, and a pair of lead-in wires 4A, 4B are sealed to the other stem part 3B. located 1
A book lead-in wire 5 is sealed with two lead-in wires 6A and 6B on both sides thereof. Stem part 3A, 3
The inside of the valve 1 sealed with B is filled with an inert gas such as xenon at a relatively high pressure of 100 Torr so as not to contain mercury vapor.

One internal discharge electrode 7 is provided on the pair of lead-in wires 4A, 4B, and the other internal discharge electrode 8 is provided on the lead-in wire 5 opposing this. Each of the internal electrodes 7 and 8 described above is not particularly limited, but
Two electrode plates 9 made of iron plated with nickel and coated with an alloy getter mainly composed of an intermetallic compound made of zirconium and aluminum.
One internal discharge electrode 7 is formed by joining the two electrode plates 9 described above in a V-shape, and the other internal discharge electrode 8 is formed by joining two electrode plates 9 flatly.

A light-emitting filament 10 made of tungsten or the like is installed over the lead-in wires 6A and 6B, and is disposed opposite to the middle part of the internal discharge electrode 8. Although not particularly limited, this light-emitting filament 10 has a structure in which an outer wire is first wound around a core wire, and the outer wire is wound secondly as an integral part, and an electron emitting material or an emitter is placed between the core wire and the first wound outer wire. BaCO ₃ that functions as a substance,
It is filled with alkaline earth oxides such as SrCO ₃ and CaCO ₃ . Most of the surface of the outer wire (not shown) of the light emitting filament 10 is exposed without being buried in the electron emitting material, and emits light when energized.

Next, an example of the operation when lighting the discharge lamp of this embodiment will be explained.

When the pressure of the filled gas increases, the ability to generate the electron avalanche required to start the discharge decreases, and in the dark, there is a shortage of initial electrons required to generate the electron avalanche. Under such conditions, for example, the lead-in wire 5 is coupled to the AC amplitude output terminal of a high-frequency inverter (not shown) via a discharge current limiting ballast capacitor (not shown), and the lead-in wires 4A and 4B are connected to the ground of the high-frequency inverter (not shown). It is coupled to the potential output terminal to form a high electric field between internal discharge electrodes 7 and 8. At the same time, the lead-in wires 6A and 6B are connected to a DC power supply circuit (not shown) to form a closed circuit including the light-emitting filament 10, and the filament 10 is energized. As a result, the light-emitting filament 10 emits light and transmits the light to the internal discharge electrode 8 nearby.
radiate to. Internal discharge electrode 8 that receives this radiation light
generates photoelectrons due to the photoelectric effect, and these photoelectrons are used as initial electrons to generate an electron avalanche required to start a discharge. Collision ionization of xenon atoms is caused by acceleration in an electric field.
The cations thus generated collide with the internal discharge electrodes 7, 8 of the cathode cycle and further emit secondary electrons. Due to such γ action, cumulatively 2
Next, when the emission of electrons increases, the discharge state changes to abnormal glow discharge or arc discharge, and cathode spots are formed in the internal discharge electrodes 7 and 8, and thermionic emission starts, resulting in a sustained discharge. achieve. In this way, even in darkness, the initial electrons for generating the electron avalanche required to start the discharge are generated by the emitted light from the light-emitting filament 10.
Delays in starting and uneven starting characteristics due to dark effects can be prevented without using radioactive isotopes or external light emitting elements.

When such a sustained discharge is achieved, ultraviolet rays are emitted by the positive column obtained from the discharge,
This ultraviolet light excites the phosphor coating 2 to generate visible light.

Since the light-emitting filament 10 is electrically insulated from the internal discharge electrodes 7 and 8, in other words, the lead-in wires between the internal discharge electrodes 7 and 8 and the light-emitting filament 10 are individualized. The circuit for lighting the light emitting filament 10 and the high frequency inverter circuit for applying discharge power to the discharge electrodes 7 and 8 can constitute an independent closed circuit. As a result, when an electric field is formed between the internal discharge electrode 8 and the light-emitting filament 10, photoelectrons as initial electrons are also accelerated by this electric field, so that even in the dark, the cathode The formation of dots is further accelerated.

Furthermore, the fact that the circuit for lighting the light-emitting filament 10 and the high-frequency inverter circuit for applying discharge power to the discharge electrodes 7 and 8 can be configured as independent closed circuits means that the light-emitting filament 10 can be configured as an independent closed circuit.
The current and voltage applied to the internal discharge electrodes 7 and 8 can be controlled to be below the rated value regardless of the discharge power applied to the internal discharge electrodes 7 and 8, which contributes to extending the life of the light-emitting filament 10. Furthermore, since the light-emitting filament 10 during sustained discharge does not substantially function as an internal discharge electrode, the light-emitting filament 10 at this time does not need to function as an internal discharge electrode.
0 receives less electron impact than the internal discharge electrodes 7 and 8. Due to these, it becomes possible to ensure a long life even for a light-emitting filament when a non-preheated internal discharge electrode that does not use a filament is employed.

Furthermore, by filling the coil of the light-emitting filament 10 with an electron-emitting substance as in this embodiment, electrons are efficiently emitted from the electron-emitting substance due to the heat generated when the light-emitting filament 10 is energized. These emitted electrons promote the production of cations for the γ action, and can further accelerate the formation of cathode spots even in the dark. Since such an electron-emitting substance is provided in the light-emitting filament 10, which is not substantially used as a discharge electrode for sustained discharge, as described above, electron impact during sustained discharge is reduced. This reduces the rate of disintegration of the electron emitting material.

In order to extend the life of the filament 10 as much as possible, it is desirable to cut off the electricity to the light-emitting filament 10 after the discharge lamp reaches a sustained discharge state.

2A and 2B are a partially longitudinal plan view and a partially longitudinal front view of a discharge lamp according to another embodiment of the present invention. The discharge lamp shown in the same figure is different from the discharge lamp shown in FIG.
The difference is that it is arranged so as to protrude toward the front, and the other configurations are the same as in FIG. In particular, the configuration shown in FIG. 2 is suitable when the inner diameter of the valve 1 is small. That is, it becomes easy to incorporate the light emitting filament 10 into a narrow space without contacting the internal discharge electrode 7 or the inner surface of the bulb 1.

3A, B, and C are a partial longitudinal plan view and a partial longitudinal front view of a discharge lamp according to another embodiment of the present invention;
FIG. The discharge lamp shown in the figure has a so-called aperture type in which a reflective coating 13 is provided on the outer surface of the bulb 11, leaving a narrow slit 12 along the length of the bulb 11, to increase luminous intensity or brightness. This is applied to a configuration like this. That is, in order to attract the positive column to the phosphor coating 14, a plurality of external electrodes 15A, 15B, for example, two external electrodes 15A and 15B are provided on the outer surface of the bulb 11, and the external electrodes 15A and 15B are provided on the outer surface of the bulb 11 in correspondence with the respective external electrodes 15A and 15B.
internal discharge electrode 16 on at least one end side of
A, 16B are also provided independently in plural numbers, and furthermore, a light emitting filament 18 is installed over a pair of lead-in wires 19A, 19B near the internal discharge electrode 17 on the opposite side.

When driving this discharge lamp to light up, a high frequency inverter can be used.
0B, each of the leads 21A and 21B drawn out from the external electrodes 15A and 15B is individually coupled to an AC amplitude output terminal of a high frequency inverter (not shown) via a discharge current limiting ballast capacitor (not shown), The other internal discharge electrode 17
The lead-in wire 22 coupled to is connected to the ground potential output terminal of the high frequency inverter (not shown).

When high frequency power is applied to the discharge lamp from this high frequency inverter, the internal discharge electrodes 16A, 16B and the other internal discharge electrode 17 are connected to each other.
A glow discharge is generated between the two, and the phosphor coating 14 is excited to emit light by ultraviolet rays generated from the spectrum of the inert gas. Here, an internal electrode 16 on one end side of the bulb is provided independently corresponding to the plurality of external electrodes 15A, 15B.
A, 16B generates a positive column between them and the internal electrode 17 on the other end side facing them, but the generated positive column is individually exposed to the phosphor due to the action of the corresponding external electrodes 15A, 15B. They are attracted in parallel to the coating 14, which results in an increase in the discharge area in the immediate vicinity of the phosphor coating 14. This increase in discharge area acts to increase the light output approximately in proportion to the current flowing through the discharge lamp when the current is increased in proportion to the number of external electrodes. That is, the critical point or saturation point of the light output, which can be increased in response to an increase in the current flowing through the discharge lamp, is raised. Therefore, it becomes possible to efficiently obtain high light output by increasing the current flowing through the discharge lamp.

In a discharge lamp having such a structure, as in the above embodiment,
By energizing the light emitting filament 18 and emitting light to the internal discharge electrode 17, it is possible to prevent delays in starting and uneven starting characteristics due to dark effects without using radioactive isotopes or external light emitting elements. Get the effect.

Although the present invention has been described in detail above, the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof.

For example, the present invention can be applied to a discharge lamp whose bulb is filled with mercury vapor. Furthermore, the structure of the internal discharge electrode is not limited to a plate-shaped electrode, and can be changed to any suitable structure that satisfies the conditions for use without preheating.

Further, when lighting a discharge lamp, by selecting the current level, cycle, and timing of energization for the light-emitting filament, it is possible to prevent the light-emitting filament from being subjected to ion bombardment at all or to that extent.

[Effect of idea]

Since the discharge lamp of the present invention has a light-emitting filament near the internal discharge electrode that is electrically insulated from the internal discharge electrode, there is no need to use a radioactive isotope or an external light-emitting element, and there is no delay in starting due to the dark effect. This has the effect of preventing unevenness in starting characteristics.

In particular, since the light-emitting filament is electrically insulated from the internal discharge electrode, the lighting closed circuit including the light-emitting filament and the discharge driving closed circuit including the internal discharge electrode are configured as separate closed circuits. By forming an electric field between the light-emitting filament and the internal discharge electrode in its vicinity during the lighting drive operation of the discharge lamp, this electric field also accelerates the initial electrons and causes the γ action to occur. This has the effect of further accelerating the formation of cathode spots.

In addition, since the closed circuit for lighting and the closed circuit for driving discharge can be configured separately, the power given to the light emitting filament can be controlled below the rated value, regardless of the discharge power for the internal discharge electrode. This can contribute to extending the life of the light emitting filament. Furthermore, since the light-emitting filament does not substantially need to function as an internal discharge electrode during sustained discharge, the light-emitting filament is not subjected to electron bombardment at this time compared to the internal discharge electrode.
These advantages have the effect that when a non-preheated internal discharge electrode that does not use a filament is employed, a long life can be guaranteed for the light-emitting filament as well.

By filling the coil of the light-emitting filament with an electron-emitting substance, the electrons emitted from the electron-emitting substance due to the heat generated when the light-emitting filament is energized are also cations for the γ effect, similar to the photoelectrons mentioned above. This facilitates the formation of cathode spots even in the dark. By providing such an electron emitting material in a light emitting filament that is not used as a substantial discharge electrode, electron impact during sustained discharge can be reduced and the disintegration rate of the electron emitting material can be eased. The effect is that it can be done.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a partially longitudinal plan view and a partially longitudinal front view of a discharge lamp which is an embodiment of the present invention, and FIGS.
B is a partially longitudinal plan view and a partially longitudinal front view of a discharge lamp that is another embodiment of the present invention; FIGS. 3A, B, and C are partially longitudinal plan views of a discharge lamp that is another embodiment of the present invention; They are a partial vertical front view and a cross-sectional view. 1... Bulb, 2... Fluorescent coating, 3A, 3B
...Stem part, 4A, 4B, 5, 6A, 6B...
Leading wire, 7, 8... Internal discharge electrode, 10... Light emitting filament, 11... Bulb, 15A, 15
B... External electrode, 16A, 16B, 17... Internal discharge electrode, 18... Light emitting filament.

Claims (1)

[Claims for Utility Model Registration] 1. A non-preheating internal discharge electrode is enclosed within a bulb that has a fluorescent coating on its inner surface and is filled with inert gas, and is located near the internal discharge electrode. A discharge lamp in which a light-emitting filament is arranged so as to be electrically insulated from the internal discharge electrode. 2 The light emitting filament has a coil shape,
2. The discharge lamp according to claim 1, wherein the coil is filled with an electron emitting material.