JPH0697604B2 - Electrodeless discharge lamp device - Google Patents

Description

Description: TECHNICAL FIELD The present invention encloses a gas body such as a rare gas or a metal vapor in a translucent valve, and applies a high frequency voltage to a coil circulated outside the valve, Discharge the gas inside,
The present invention relates to a so-called electrodeless discharge lamp device in which the emitted light or the generated ultraviolet light is used after being converted into visible light by a phosphor coated on the inner wall of the bulb.

BACKGROUND ART Conventionally, electrodeless discharge lamps have been researched and developed in various places because they have characteristics such as small size, high output, and long life.
There are various uses, but for example, an application as an original reading light source for an optical device such as an electronic copying machine or a facsimile is also conceivable.

The background of the use of the electrodeless discharge lamp as a document reading light source is as follows. That is, since the document reading light source requires a light amount, a halogen bulb, an ultra-high output straight tube fluorescent lamp or the like is currently used. However,
Halogen bulbs provide a sufficient amount of light, but have a short life,
It also has poor earthquake resistance. Further, since the efficiency is low, the heat generation is very large, a forced air cooling fan and a heat filter are required in the equipment, and the cost is high due to accident countermeasures.

On the other hand, an ultra-high output straight tube fluorescent lamp has the advantages of higher efficiency, less heat generation, and longer life than a halogen bulb, but on the contrary, there is a problem that a sufficient amount of light cannot be obtained. Because the light output of the fluorescent lamp is
It is generally well known that the filament is broken when a current exceeding the allowable current is applied due to the restriction of the filament electrode inside the lamp.Therefore, the electrode must be large, that is, the lamp diameter must be large or multiple The desired amount of light is obtained by arranging these lamps side by side. However, if such a measure is taken, there is a big problem that the space of the light source section becomes large and the optical design is not easy.

In contrast to such a conventional light source, the electrodeless discharge lamp described above does not have an electrode inside the lamp, so that there is no restriction due to the electrode and high output and miniaturization are possible.
Further, when an electrodeless fluorescent lamp in which a fluorescent material is applied to the inner wall of the lamp and a rare gas such as argon and a metal such as mercury are sealed in the lamp is used, the efficiency is high and the amount of heat generation is small.
Further, unlike the conventional straight-tube fluorescent lamp, it has various features such as no decrease in light in the vicinity of both tube end electrodes and excellent uniformity of light in the lamp tube axis direction.

FIG. 5 shows an original reading light source device using an electrodeless fluorescent lamp as described above. In the figure, reference numeral 1 is a so-called aperture type electrodeless fluorescent lamp, which does not have an electrode inside the bulb 2, A reflective film 3 of titanium oxide or the like and a phosphor 4 are deposited on the wall surface, leaving a part of the inner wall as an opening 5, and a rare gas such as argon or a metal such as mercury is placed inside the bulb 2. Is enclosed. Reference numeral 6 is an induction coil wound along the longitudinal direction of the electrodeless fluorescent lamp 1, 7 is a high frequency oscillation circuit, and 8 is a power source.

Such a device increases the light output from the opening 5 by making the lamp 1 into an aperture type as shown in FIG. 6, and at the same time, a reflector mirror arranged on the front surface of the lamp 1 based on the optical design. The optical illuminating means as described above ensures the necessary illuminance on the original surface.

FIG. 7 is a schematic configuration diagram showing the light source section of the copying machine.
Is a document table, 10 is a reflecting mirror, 11 is a photosensitive drum or CCD (charg
A light receiving portion 12 such as an e-coupled device) is an original, light emitted from the lamp 1 passes through the original table 9, and light reflected by the original 12 reaches the light receiving portion 11 via a mirror or a lens. .

However, such a document reading light source device has the following problems. That is, as shown in FIG. 8, if a high frequency current flows in the direction of the arrow in the induction coil 6 wound along the longitudinal direction of the electrodeless fluorescent lamp 1 at a certain time, the induction in the lamp 1 by the magnetic field then occurs. Like the electric field, the current Ia flows in the opposite direction to the coil current,
A loop current is formed in the lamp 1. At this time, if the electric power supplied to the lamp 1 is large, high-density plasma is uniformly formed inside the lamp 1, but the electric power supplied to the lamp 1 is, for example, dimmed. If the number is reduced, the high-density plasma may sometimes not be uniformly formed in the lamp 1 and may shrink to the region indicated by the broken line in FIG. At this time, the induced current Ib in the plasma seems to form a loop in the contracted plasma. This contracted plasma is not stable, and its region changes irregularly due to the metal vapor pressure inside. It has been confirmed by experiments that the conditions under which such contracted plasma is formed are influenced by many factors such as the shape of the lamp 1, the tube diameter, the internal gas pressure, and the supplied power.

Therefore, in the conventional electrodeless fluorescent lamp 1, when the power supplied is small, the plasma formed inside the lamp becomes irregular, which causes the light distribution in the longitudinal direction of the lamp to be extremely uneven, and When used as a document reading light source, this is a major drawback. Further, when electric power is supplied so that irregular contracted plasma is not formed, the tube wall temperature of the lamp 1 becomes extremely high, which is a serious problem in terms of quantum efficiency and life of the phosphor 4.

[Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrodeless discharge lamp device which uniformly emits light over the entire area of the lamp and is excellent in light emission efficiency and life. There is.

DISCLOSURE OF THE INVENTION The present invention relates to an electrodeless discharge lamp device in which a gas body enclosed in the bulb is discharged and emits light by applying a high-frequency voltage to a coil circulated outside the translucent bulb. The valve is constituted by a valve having at least two straight pipe portions which are parallel to each other and which communicate with each other near both ends of the straight pipe portion to form a circulating discharge path. It is characterized in that it is arranged along the electric path.

Hereinafter, the present invention will be described based on examples. FIG. 1 shows an embodiment of the present invention. The lamp 21 has two straight tubes 22.
While a and 22b are arranged in parallel with each other, both ends of the straight tubes 22a and 22b are connected to each other via bridges 28 and 29, respectively, to form one orbiting discharge path as a lamp internal space. Coil externally and along the orbiting discharge path
26 are arranged. In addition, inside the lamp 21,
As a gas body, a rare gas such as argon or a metal such as mercury in addition to the rare gas is sealed. Also, each straight pipe 22
A phosphor is applied to the inner wall surfaces of a and 22b as needed.

With this configuration, when a high-frequency current flows through the coil 26 in the direction of the arrow in the figure, the induced current Ia that flows in the lamp 21 due to the high-frequency current flows in the lamp 21 so as to form a loop. In this case, even if the power is reduced as in the conventional example, the induced current does not form another short-circuited loop, but continuously maintains a loop along the coil 26, and uniform light emission is maintained over the entire lamp. .

Moreover, since the lamp 21 is divided by the two straight tubes 22a and 22b, the surface area with respect to the volume is increased as compared with the conventional example. This means that when the same power is supplied to the lamp 21, the tube wall temperature of the lamp 21 is lower than that of the conventional example. Therefore, when the fluorescent substance is applied to the inside of the tube of the lamp 21, it is advantageous for the fluorescent substance, and it is possible to prevent the quantum efficiency of the fluorescent substance from decreasing and to prolong the life of the lamp significantly.

Next, FIG. 2 shows an example in which the electrodeless discharge lamp device according to the present invention is used as a document reading light source device.
The straight tube portions 22a and 22b of the lamp 21 are formed with opposing openings 25 and 25, respectively, as shown in the figure, and constitute an aperture type lamp. In the figure, 23 is a reflective film as described above, and 24 is a phosphor.

In such an apparatus, the emitted light from the straight tube portions 22a and 22b of the lamp 21 passes through the document table 9 through the aperture portion, that is, the opening 25, and is irradiated onto the document 12. The reflected light is a mirror
The light enters the light receiving unit 11 through the lens 30 and the lens 31. In this case, regarding the illuminance distribution in the lamp longitudinal direction, the straight pipe portion 22a,
Light is uniformly emitted between the bridges 28 and 29 connected to both ends of 22b, and the uniform emission length with respect to the entire length in the lamp longitudinal direction is
The length is significantly longer than that of the ultra-high power straight tube fluorescent lamp having electrodes inside the lamp, and as a result, the length of the lamp can be shortened, that is, the device can be downsized.

FIG. 3 shows a different embodiment of the present invention. The difference from the above embodiment is that the coil 26 is formed in a flat plate shape,
By arranging it so as to be in close contact with the outer periphery of the lamp 21,
Since other configurations are the same as those of the above-described embodiment, the description will be omitted by giving the same reference numerals to the same configurations. The coil 26 may be formed by directly vapor-depositing a heat-resistant conductive coating on the lamp 21.

With this configuration, the contact surface of the coil 26 to the lamp 21 is an optical reflection surface, and the straight tube portion 22a of the lamp 21,
The radiated light from 22b is effectively applied to the document surface through the opening 25 without applying a reflective film to the inner wall of the lamp 21. Therefore, the lamp cost can be reduced, the heat radiation effect from the surface of the coil 26 can be increased, the tube wall temperature of the lamp 21 can be further reduced, and the luminous efficiency of the lamp due to the increased degree of coupling between the coil 26 and the lamp 21. Can be improved.

FIG. 4 shows a further different embodiment of the present invention. A lamp 21 is composed of a bulb 22 bent in a U shape and a stem 32 connecting both ends of the bulb 22. 32 is preferably glass or ceramics. In addition,
In the figure, reference numeral 33 denotes a coldest spot control unit, which is a place where the internal temperature is the lowest during lamp lighting, that is, a coldest spot. As a result, the internal mercury vapor pressure can be controlled at this location. For example, by winding a heater around the coldest spot control unit 33 to preheat it, the starting stability at low temperatures is improved. Further, if the coldest spot control unit 33 is provided with a heat dissipation plate, it is possible to prevent a decrease in light output due to an excessive increase in mercury vapor pressure even during long-time lighting. Of course, it is also possible to provide a combination of a heater and a heat dissipation plate in the coldest spot control section 33, and to supply a current at a low temperature to raise the temperature of the heater and cut off the current when the temperature rises to form a discharge plate. Furthermore, by providing the coldest spot control unit 33,
It is also effective in that it is possible to improve the brightness unevenness due to the extraction of mercury on the light emitting surface of the lamp bulb, which has been a problem in conventional lamps.

Further, in this embodiment, both ends of the U-shaped valve 22 are connected to the stem 32.
However, one straight discharge path is formed by connecting the two straight pipes in parallel with each other as in the first embodiment, and connecting both ends of each straight pipe by a stem, Alternatively, a structure may be adopted in which one circulated discharge path is formed, or two straight pipes are arranged in parallel with each other instead of a U-shaped bulb, and one end of each is connected by a bridge. A configuration in which the straight pipes of the book are communicated with each other and the other end thereof is communicated with the stem may be used. Further, regarding the provision of the coldest spot control unit 33, by providing a protrusion that communicates with the lamp 21 in each of the above-mentioned embodiments,
It is clear that the same effect can be obtained.

[Advantages of the Invention] As described above, according to the present invention, by applying a high-frequency voltage to a coil wound outside the translucent bulb, the gas body enclosed in the bulb is discharged and emits no electrode. In the electric light device, the bulb is constituted by a bulb having at least two straight pipe portions that are parallel to each other, and communicating with each other near both ends of the straight pipe portion to form a circulating discharge path. By arranging along the above-mentioned circulation discharge path, a local loop of induced current is not formed in the lamp bulb, and the loop along the coil is constantly maintained to maintain uniform light emission throughout the lamp. It was possible to provide an electrodeless discharge lamp device.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a schematic configuration view showing an example in which the same is used as a document reading light source device, and FIG. 3 is a perspective view showing a different embodiment of the present invention. FIGS. 4 and 5 are perspective views showing still another embodiment of the present invention, FIG. 5 is a perspective view showing a conventional example, FIG. 6 is a sectional view of the same lamp section, and FIG. 7 is a light source section of a copying machine. FIG. 8 is a schematic diagram showing the operation, and FIG. 8 is a schematic view for explaining the operation of the conventional example. 21 ... Lamp, 22 ... Bulb, 26 ... Coil.

Claims (1)

[Claims] 1. An electrodeless discharge lamp device in which a gas body enclosed in the bulb is discharged and emits light by applying a high-frequency voltage to a coil wound outside the translucent bulb. The valve has at least two straight pipe portions that are parallel to each other, and is formed of a valve that communicates near both ends of the straight pipe portion to form a circulating discharge path, and the coil is provided along the circulating discharge path. An electrodeless discharge lamp device characterized by being provided.