JPS61185857A - Electrodeless discharge lamp - Google Patents

Abstract

PURPOSE:To increase the light output while to improve the uniformity of brightness in axial direction by arranging a pair of metallic conductors in linear lamp along the axial direction of bulb while sandwitching the bulb thereby making the light emission length longer than the bulb length. CONSTITUTION:Metallic conductors 24, 25 are arranged in axial direction of bulb while sandwitching the bulb 20. High frequency electromagnetic field produced through high frequency oscillation circuit 26 will excite the metallic vapor in the bulb 20 to dissociate electrolytically thus to emit ultraviolet ray, but since a reflection film 22 and phosphor material 23 are applied onto the inner wall face of bulb 20, it is radiated as direct and indirect lights through a slit opening 21. Since the phosphor material 23, the reflection mirror 22 and the bulb 20 are arranged between the metallic conductors 24, 25 and the interior of the bulb 20, deceleration of flux is never influenced to emit light through the opening 21 over the entire range in axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an electrodeless discharge lamp that discharges metal vapor sealed in a bulb and emits light using a high-frequency electromagnetic field.

(Background Art) Aperture type fluorescent lamps have been widely used as light sources for copying machines, and a lighting device using this type of lamp generally has a configuration as shown in FIG. 1. An aperture type fluorescent lamp leaves a part of the inner wall surface of the bulb l, that is, an opening 2, and a reflective film 3 made of titanium oxide or the like.
The inside of the bulb 1 is filled with metal vapor such as mercury and an inert gas such as argon. The ultraviolet rays generated by the excitation of the internal metal vapor are emitted from the opening 2 in approximately one direction either directly or via the phosphor 4 and the reflective film 3. A pair of electrodes 5.5 disposed within the valve 1 are connected to a power source 7 via a ballast 6 and also to a starting control circuit 8.

However, in the light source lighting device for a copying machine as described above, since the electrode 5 is provided inside the bulb I, there are many problems such as reduction of the luminous flux at the end of the tube, blackening of the end of the tube during the life of the lamp, and difficulty in instantaneous lighting. In order to improve these problems, we created a high-frequency electromagnetic field between two metal conductors fitted near the end of the straight tube valve, which does not have an electrode inside the valve. proposed a light source lighting device for a copying machine using so-called electrodeless discharge, which is configured to excite metal vapor sealed in a bulb to emit light. FIG. 2 shows an example of such a light source lighting device for a copying machine, in which 10.11 is a metal conductor, 12
1 is a high frequency oscillation circuit, 13 is a straight tube valve, 14 is an opening, and 15 is a power source. Therefore, such a lighting device is
Since there are no electrodes or emitter materials inside the bulb 13, there is no luminous flux reduction at the end of the tube or blackening of the end of the tube during the lamp life as described above, and the lamp also has features such as excellent flashing life and instant lighting. have

However, in such a light source lighting device for a copying machine, there is a metal conductor 10 near both ends of the bulb 13 that does not transmit light.
11, radiation from inside the bulb 13 covered by the metal conductors 10 and 11 is blocked, and the substantial length of light emitted in the tube axis direction is shortened, resulting in poor efficiency as an apparatus. In other words, in a device that requires a light emitting length in the tube axis direction, such as a light source lighting device for a copying machine, the lamp length is increased by the width of the two metal conductors 10 and 11 in addition to the predetermined light emitting length. The width of the metal conductors 10 and 11 is determined by the relationship between the required optical output and the circuit design, oscillation frequency, etc., and cannot be made narrower without limit.
The wider the metal conductor 10.11, the greater the input into the lamp, which is advantageous in terms of light output). Therefore, there was a problem that the effective length of the lamp was shortened.

Furthermore, a high frequency oscillation circuit 12 that generates a high frequency electromagnetic field
As a specific circuit, the well-known Clapp circuit shown in Figure 3 is used in terms of design and cost, but the high frequency potential at point a in the figure is high. point b is at a low potential (so-called cold). In other words, since there is a high frequency potential difference between the metal conductors 10 and 11 fitted to the bulb 13,
The luminance of the bulb 13 in the tube axis direction has a negative gradient from point a to point b. For this reason, the above-mentioned light source device for an electrodeless copying machine has a major problem in terms of uniformity of brightness.

(Object of the Invention) The present invention has been made in view of the above problems, and its purpose is to increase the light output by increasing the light emission length with respect to the bulb length in an electrodeless discharge lamp, and to increase the luminance in the tube axis direction. The goal is to improve the uniformity of the process.

(Disclosure of the Invention) The present invention provides an electrodeless discharge lamp in which a high-frequency electromagnetic field is applied to a pair of metal conductors disposed in a straight lamp bulb to excite metal vapor sealed in the bulb to emit light. , characterized in that both the metal conductors are arranged facing each other along the bulb axis direction so as to sandwich the bulb.

The present invention will be explained below based on the embodiment shown in FIGS. 4 and 5. In the figure, reference numeral 20 denotes a straight tube-shaped lamp bulb, and a slit-shaped opening 21 is left on the inner wall surface of the bulb 20, and a reflective film 22 such as titanium oxide and a phosphor 23 are coated. Metal vapor such as mercury and inert gas such as argon are sealed inside.

Metal conductors 24 and 25 are arranged along the axial direction of the bulb 20 and facing each other so as to sandwich the bulb 20 therebetween. 26 is a high frequency oscillation circuit, and 27 is a power supply. Note that, as shown in FIG. 5, the metal conductors 24 and 25 are desirably disposed so as to be in contact with the outer wall surface of the bulb 20, but the present invention is not limited to this. If .25 does not touch each other, its shape,
The installation location does not matter.

Thus, the metal conductor 10 according to the conventional example. , 11 are fitted near the tube end of the lamp bulb 13, so the so-called inter-electrode distance (the metal conductors 10 and 11 can be considered as external electrodes) is approximate to the bulb length; According to the present invention, the so-called inter-electrode distance is
There is a difference in that the diameter is similar to that of the pipe, but there is no major difference in terms of circuit operation.

According to the present invention, the metal vapor within the bulb 20 is excited and ionized by the high frequency electromagnetic field generated by the high frequency oscillation circuit 26, and ultraviolet rays are emitted. Since the body 23 is coated, the slit-shaped opening 21 emits direct light and indirect light to the outside. Therefore, since the metal conductors 24 and 25 are connected to the inside of the pulp 20 via the phosphor 23, the reflective film 22, and the pulp 20, they do not have the same effect on luminous flux attenuation, and the bulb 20 is Emit light over the entire axial range.

Further, as an oscillation circuit 26 that generates a high frequency electromagnetic field,
When a ramp circuit is used as in the conventional example, a high frequency potential difference occurs between c and d shown in Fig. 4, and the luminance distribution in the tube radial direction is not uniform, but the high frequency potential along the tube axis direction is Since they are the same, the brightness distribution is uniform.

In the above embodiments, an aperture lamp for a copying machine has been described, but the present invention is not limited to this, and can also be applied to a general discharge lamp.

(Effects of the Invention) As described above, the present invention applies a high frequency electromagnetic field to a pair of metal conductors disposed in a straight tube-shaped lamp bulb to excite the metal vapor sealed in the bulb to emit light. In the electrodeless discharge lamp, by arranging the metal conductors facing each other along the bulb axis direction so as to sandwich the bulb, the light emitting length relative to the pulp length can be lengthened, and the light output can be increased. We were able to provide an electrodeless discharge lamp that can improve the uniformity of luminance in the tube axis direction.

[Brief explanation of the drawing]

1 and 2 are simplified diagrams showing a conventional example, FIG. 3 is a circuit diagram showing an example of a high frequency oscillation circuit used in the conventional example, and FIG. 4 is a simplified diagram showing an embodiment of the present invention. Fifth
The figure is a partially sectional perspective view of the valve section according to the above embodiment. 20... Lamp bulb, 21... Opening, 24.2
5... Metal conductor, 26... High frequency oscillation circuit.

Claims (1)

[Claims] (1) In an electrodeless discharge lamp that applies a high-frequency electromagnetic field to a pair of metal conductors arranged in a straight lamp bulb to excite metal vapor sealed in the bulb and emit light,
An electrodeless discharge lamp characterized in that both of the metal conductors are arranged facing each other along the bulb axis direction so as to sandwich the bulb.