JPH0452934Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an electrodeless discharge lamp operated at high frequency.

[Background Art] Generally, discharge lamps are classified into electrode type as shown in FIG. 5 and electrodeless type as shown in FIG. 6. The electrode type discharge lamp shown in FIG. 3 is widely used as a fluorescent lamp or a high-pressure mercury lamp. In the case of a fluorescent lamp, an airtight space 2 is formed by a translucent bulb 1 made of a glass bulb. A predetermined amount of discharge gas such as mercury vapor or rare gas is sealed inside the bulb, a phosphor 3 is coated on the inner surface of the translucent bulb 1, and discharge filament electrodes 4 for emitting thermoelectrons are provided at both ends. ing. Such a fluorescent lamp has a current limiting impedance 6 between the filament electrodes 4 which are appropriately preheated by a preheating means.
By applying a power source 7 through the filament electrode 4, a discharge is generated between the filament electrodes 4, and the ultraviolet rays generated by this discharge are converted into visible light by the phosphor 3, so that illumination light can be obtained. There is. However, such an electrode discharge lamp has the problem that it is difficult to turn it on instantly, to be compact, and to achieve high output, and furthermore, the thermionic emission characteristics of the filament electrode 4 are deteriorated, resulting in a short life span.

On the other hand, in the electrodeless discharge lamp shown in FIG. 4, a predetermined amount of discharge gas such as mercury vapor or rare gas is sealed in an airtight space 2 formed by a closed cylindrical light-transmitting bulb 1. At the same time, a phosphor 3 is applied to the inner surface of the light-transmitting bulb 1, a ring-shaped conductor 8 for applying a high-frequency power source is inserted to both ends of the light-transmitting bulb 1, and a high-frequency power source 9 is applied between the ring-shaped conductors 8. By applying a voltage, a discharge is caused within the translucent bulb 1, and the ultraviolet rays generated by the discharge are converted into visible light by the phosphor 3 to obtain illumination light. Although such electrodeless discharge lamps have the advantage of being faster to light than electroded discharge lamps, can be made smaller and have higher output, and have a longer lifespan, As the time becomes longer, a so-called blackening phenomenon occurs in which mercury adheres between the phosphor 3 and the light-transmitting bulb 1 in the vicinity of the ring-shaped conductor 8, resulting in a black portion X, as shown in FIG. There was a problem in that the luminous flux decreased and the light emitted from the portion L where the ring-shaped conductor 8 was extrapolated was blocked by the ring-shaped conductor 8, so that the light emission could not be used effectively.

[Purpose of the invention] The present invention has been made in view of the above points, and its purpose is to reduce the reduction in luminous flux due to the blackening phenomenon and shielding of the insertion part of the conductor to which a high frequency voltage is applied. An object of the present invention is to provide an electrodeless discharge lamp that can effectively utilize light emission without any problems.

[Disclosure of the invention] (Example 1) Fig. 1 shows an example of the invention, in which a predetermined amount of air is poured into an airtight space 2 formed by a closed cylindrical light-transmitting bulb 1. A discharge gas such as mercury vapor or rare gas is filled in, and a partially opened cavity 10 is provided in the translucent bulb 1.
A conductor 11 to which a high frequency voltage is applied is inserted inside the light-transmitting bulb 1.
An electrodeless fluorescent lamp is formed by applying a phosphor 3 to the inner surface of the lamp. Note that it goes without saying that it is not necessary to apply the phosphor 3 if there is no need to convert it into visible light, and in order to effectively output ultraviolet rays, it is necessary to use an ultraviolet transmitting material (for example, quartz) as the light transmitting bulb 1. Just use it. Further, the gas pressure of the discharge gas sealed in the airtight space 2 may be set to a low pressure like that of a general fluorescent lamp,
The pressure may be high as in the case of a lamp.

Now, by applying a high frequency voltage from the high frequency power supply 9 between the conductors 11, a discharge occurs in the light-transmitting bulb 1 and ultraviolet rays are generated, as in the conventional example shown in FIG. The light is then converted into visible light and illumination light is obtained. Here, if the discharge time becomes longer, a blackening phenomenon will occur due to the adhesion of mercury, but this blackening phenomenon occurs on the inner surface of the light-transmitting bulb 1, that is, the cavity, where the conductor 11 is adjacent, as shown in FIG. This blackened portion Y does not occur on the light output surface, that is, the surface coated with the phosphor 3, so that the reduction in luminous flux due to blackening does not occur. In addition, since the conductor 11 is inserted into the cavity 10, the light output surface is not blocked by the conductor 11 and the luminous flux is not reduced as in the conventional example shown in FIG. I'm starting to be able to do it.

[Effects of the invention] As described above, the present invention seals a predetermined amount of discharge gas such as mercury vapor or rare gas in an airtight space formed by a closed cylindrical light-transmitting bulb, and Cavities with openings on the end faces are provided at both ends of the light-transmitting bulb, and conductors to which a high-frequency voltage is applied are inserted into each cavity, and the light output of the electrode portion is reduced due to the blackening phenomenon caused by electric field concentration. This has the effect of being able to prevent a decrease in the temperature. In other words, blackening due to electric field concentration occurs on the outer surface of the cavity formed by recessing the end face of the bulb (the outer surface of the part that protrudes into the bulb), so blackening occurs on the outer peripheral surface of the translucent bulb. Therefore, there is an effect that a decrease in the optical output of the electrode portion can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an embodiment of the present invention.
Fig. 2 is an explanatory diagram of the same operation as above, Fig. 3 is a partially cutaway front view of a polarized discharge lamp, Fig. 4 is a partially cutaway front view of a conventional electrodeless discharge lamp, and Fig. 5 is an explanation of the operation of the same as above. It is a diagram. 1 is a translucent bulb, 2 is an airtight space, 3 is a phosphor, 9 is a high frequency power source, 10 and 10a are cavities, 1
1 and 11a are conductors.

Claims (1)

[Scope of utility model registration request] A predetermined amount of discharge gas such as mercury vapor or rare gas is sealed in an airtight space formed by a closed cylindrical translucent bulb, and an opening is provided at each end of the translucent bulb. An electrodeless discharge lamp characterized in that a cavity is provided and a conductor to which a high frequency voltage is applied is inserted into each cavity.