The present invention relates to a glow discharge lamp which is suitable as a glow starter for starting a fluorescent lamp or a hot-cathode fluorescent lamp to operate, a luminaire utilizing the glow discharge lamp and an electrode for a glow discharge lamp.
A glow discharge lamp has been in heavy usage as a glow starter for starting a discharge lamp such as a cold-cathode discharge lamp, a hot-cathode fluorescent lamp etc., and a discharge lamp for display units.
The starting time of the glow discharge lamp used as a glow starter tends to become longer in the dark. Therefore, it has been desired to shorten the discharge starting time in the dark. Here, the discharge starting time of the glow starter is the sum of the discharge delay time, the glow discharge duration, the extinction time, and the pulse generating time. The reason of the discharge starting time becoming longer in the dark is because the supply amount of primary electrons runs short, and the discharge delay time becomes longer.
Conventionally, radioisotopes as described below have been employed for shortening the discharge delay time.
A very small amount of a radioisotope such as 147Pm are coated or adhered by an electrochemical process on the vicinity of the electrode, and then metal such as Ni is further plated on it (known art I).
Gaseous radioisotope such as 85Kr or 3H is filled in a discharge vessel (known art II).
Since in the known arts I and II ionizable filling in the discharge vessel is able to be constantly ionized by the radioisotope, a discharge promptly starts at the time of lighting operation. Thus an effect of shortening the discharge delay time is remarkable. However, manufacturing of radioisotope applications require production facilities which must conform a radiation safety standard and requires a strict control for safety handling even if a very small amount of radioisotope is contained therein.
For averting the drawbacks of radioisotope, a glow starter free from radioisotopes has been sought. Japanese Laid-Open Patent Application Hei.10-255724 (hereinafter, referred to as xe2x80x9cknown art IIIxe2x80x9d), discloses an application of phosphorescent phosphor for glow starters. According to the known art III, persistence is applied to an electrode surface even in the dark, so that photoelectrons are emitted, and primary electrons are supplied. Therefore, the discharge delay time is shortened. However, there is a limit to how long the specific amounts of the persistence can be preserved in a phosphorescent phosphor. According to the document, it is described that the limit of the time to preserve the specific amounts of the persistence in the Type-FL15 fluorescent lamp in the dark is 60 hours (2.5 days) to 90 hours (3.75 days) after turning on for 30 minutes with 100 lxc3x97 of light per day. Furthermore, since the phosphorescent phosphor has to be provided at a portion to which the outside light reaches, there is a restriction that a light shielding material cannot be used for a discharge vessel.
Moreover, Japanese Laid-Open Patent Application Sho.54-64873 (hereinafter, referred to as xe2x80x9cknown art IVxe2x80x9d), discloses an electroplating of zinc on electrodes in order to shorten the discharge starting time in the dark. In the known art IV, even though the plated zinc layer is oxidized, the oxidized layer sputters out by the glow discharge. So that the plated zinc layer is kept clean and tolerably active. Furthermore, the sputtering zinc atoms mate with impurity gases in the discharge vessel and adhere to the inner surface of the glass tube. Therefore, the ionizable filling is defecated and the releasing of the impurity gases from the glass tube is suppressed.
Therefore, according to the known art IV, since primary electrons are easily emitted from the electrode surface, the drawbacks shown in the known arts I to III are resolved.
However, according to the inventor""s investigation, the known art IV has a problem that zinc adhering to a bimetal movable electrode or a fixed electrode quickly sputters out in accompany with the glow discharge or the high voltage pulsing discharge. Therefore, the known art IV is impossible to preserve a quick-starting feature.
Especially, the higher the gas pressure of the ionizable filling is for suppressing the sputtering of emissive materials, the higher the discharge starting voltage will be. Accordingly, there will be the drawbacks that the discharge delay time becomes longer, and the discharge starting time also becomes longer.
Furthermore, in the known art IV, it is found to accompany a drawback that the discharge starting probability changes with the thickness of the zinc film.
Furthermore, in the known art IV, although the discharge starting operation voltage may be lowered by using zinc for an emissive material, the discharge starting voltage elevates according to the gradual exhaustion of the emissive material during the life performance, so that it becomes hard to discharge. As a result, there was a problem of the discharge starting time becoming longer.
The present invention has an object to provide a glow discharge lamp, a glow starter and an electrode for glow discharge lamps and glow starters wherein discharge starting property in the dark is improved by shortening the discharge starting time, and a luminaire using thereof.
The present invention still has an object to provide a glow discharge lamp, a glow starter and an electrode for glow discharge lamps and glow starters wherein a sputtering of emissive material is extensively decreased, and a luminaire using thereof. The present invention still has an object to provide a glow discharge lamp, a glow starter and an electrode for glow discharge lamps and glow starters wherein impurity gases in a gaseous ionizable filling is eliminated so as to suppress an undesirable discharge delay or a rise of the discharge starting voltage, and a luminaire using thereof.
The present invention still has an object to provide a glow discharge lamp, a glow starter and an electrode for glow discharge lamps and glow starters wherein the decrease of the restarting voltage is suppressed so as to stabilize their operations during the life performance, and a luminaire using thereof.
To achieve the above objects, a glow discharge lamp according to the first aspect of the present invention, comprises a discharge vessel, a pair of electrodes mounted in the discharge vessel, ionizable filling which is principally made of a rare gas filled in the discharge vessel, and an emissive material which is made of zinc simple substance adhering to at least one of the electrodes.
To achieve the above objects, a glow discharge lamp according to the second aspect of the present invention, comprises a discharge vessel, a pair of electrodes mounted in the discharge vessel, ionizable filling which is principally made of a rare gas filled in the discharge vessel, and an emissive material which is made of zinc-alloy adhering to at least one of the electrodes.
To achieve the above objects, a glow discharge lamp according to the third aspect of the present invention, comprises a discharge vessel, a pair of electrodes mounted on inside the discharge vessel, ionizable filling in the discharge vessel which is principally made of a mixture of a first gas including neon (Ne) and a second gas including at least one of krypton (Kr), xenon (Xe), and argon (Ar), and emissive material containing a zinc formed on at least one of the electrodes.
To achieve the above objects, a luminaire according to the fourth aspect of the present invention, comprises a luminaire main body, the glow discharge lamp as defined in any one of the above aspects, which is mounted on the luminaire main body and a fluorescent electrode mounted on the luminaire main body.
Additional objects and advantages of the present invention will be apparent to persons skilled in the art from a study of the following description and the accompanying drawings, which are hereby incorporated in and constitute a part of this specification.