JPS6362458A - Lighting device - Google Patents

Abstract

PURPOSE:To eliminate the uneven luminous quantity radiated from a discharge tube in the lengthwise direction by controlling the quantity of power supplied to plural coil-shaped electrodes arranged to the thin and long discharge tube stimulated by a high frequency electromagnetic field. CONSTITUTION:Plural split coil-shaped electrodes 2a-2n are arranged to the outer circumference of the discharge tube 1 along its lengthwise direction. The coil-shaped electrodes 2a-2n are connected in parallel with a high frequency application means 3, a high frequency voltage whose frequency is 8-10MHz of 200V or over is applied from the high frequency application means 3 at the normal lighting state to attain excellent lighting. Moreover, the control means 200 is provided with a switch element 201 and a switch element control means 202 controlling the high frequency power applied from the high frequency application means 3. The radiated luminous quantity of the discharge tube in the lengthwise direction is uniformed by applying optional switching control to the switch element 201.

Description

[Detailed description of the invention] 3. Detailed explanation of the invention
The present invention relates to an illumination device that can be suitably used as a document reading device that illuminates a document and reads a document image in office equipment, that is, as an exposure means. In the following, the present invention will be explained mainly in relation to a document reading device for micro-service equipment, but the application of the illumination type device according to the present invention is not limited to this device. .

′ No ゛ bi! l! lL＼Conventionally, long length (slender shape) effective as a lighting device for document reading devices, etc.
As light sources, elongated fluorescent lamps, halogen lamps, etc. are often used.

Fluorescent lamps have a low light output and are normally used as lighting devices for low-speed office equipment. If the brightness (emitted light 1M) is increased, the internal filament installed inside the fluorescent tube will melt, so there is a limit to the increase in power supply, and in reality, it is not suitable for lighting equipment for high-speed small equipment. Not suitable.

On the other hand, halogen lamps have a large luminous value and a high speed
Although it is used for dexterity, 1) it generates more light in the infrared region wavelength than the visible light region required for reading documents in office equipment, 1. It not only has poor luminous efficiency, but 2. The generated heat is large, and a cooling device, especially a large cooling device, is required to reduce this heat generation effect. I$JJ It cannot be said that this is a desirable lighting device in today's world where smaller and cheaper equipment is desired.

The present applicant has proposed an elongated lamp (51 device) which solves the drawbacks of conventional fluorescent lamps and halogen lamps and is suitable not only for general illumination but also particularly as a document reading device for office equipment. (Japanese Patent Application No. 60-78782), as shown in FIG.
An electrode 2 is provided on the outer wall of the discharge tube 1 in the form of a plurality of coils wound along the pitching direction, and a high frequency application stage 3 for supplying high frequency power to the electrode.

To explain further, the discharge tube 1 is formed by coating a phosphor inside a narrow glass tube usually made of soda glass or pyrex glass. An ionizable starting inert gas such as A high frequency voltage 1 is applied to the L-type pole 2 by a high frequency applying means 3. High frequency application means 3
may have any configuration, but for example, as illustrated in FIG. 6, a high frequency oscillation circuit 4 that oscillates a high frequency wave,
and an input type ft5 for the high frequency oscillation circuit 4.

High 1. 'An amplifier 6 for amplifying the high frequency voltage from the four-wave oscillation circuit 5 to a desired voltage, and an L for matching the high frequency voltage from the amplifier 6 with the impedance of the discharge tube l.
C coupler 7.

When a high frequency voltage is applied to the pole 2 from the high frequency applying means 3 having such a structure, the mercury gas in the discharge tube is excited by the high frequency electromagnetic field and generates ultraviolet rays. The ultraviolet rays act on the phosphor coated on the inner wall of the discharge tube to generate light in the visible range.

J, Foot Temperature In the lighting device shown in Figure 5, the electrode 2 is provided outside the discharge tube, and unlike conventional fluorescent lamps and halogen lamps, there is no filament inside the discharge tube.
It has the advantage that the degree of deterioration of the electrode is extremely small, and the electrode can be replaced once it has deteriorated.

Furthermore, such a lighting device can output a tf of 4 degrees, which is equivalent to a halogen lamp, with a lower input power than a halogen lamp, and is capable of increasing the amount of light. In addition, such lighting devices do not generate high heat like conventional halogen lamps, and have extremely good luminous efficiency. There is an advantage that a small cooling device only needs to be prepared when nine office equipment, etc. are used, and there is no need to prepare a special cooling device depending on the case.

1. The lighting device described above has various advantages as described in L, but according to the research experiments of the present inventors, using a coil-shaped electrode 2 as shown in FIG. The 'ltr,
Illumination using a so-called high electromagnetic field application type coiled electrode 2, which supplies high frequency power to a pole, generates an electromagnetic field at the electrode, and applies a strong electromagnetic field to the discharge tube, causing the discharge tube to light up. The device 100 has found that high brightness causes electromagnetic field unevenness in the longitudinal direction of the discharge tube, which becomes a source of discharge unevenness, and the light l- along the length of the discharge tube becomes non-uniform. This is considered to be because the electromagnetic field is concentrated at the center in the longitudinal direction of the H7ti pipe, and the electromagnetic field is weaker at the ends.

As a result of conducting research experiments to solve such problems, the present inventors have divided the coiled electrode into multiple pieces along the pitching direction of the discharge tube, and arranged the coiled electrode in such a manner that the supply to each coiled electrode is fixed. It has been found that the conventional problems can be solved by controlling the power individually.

The present invention has been made based on this new knowledge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-intensity, long-life lighting device that eliminates discharge unevenness in the longitudinal direction of an emission tube, that is, unevenness in emitted light μ.

Another object of the invention is, in particular, to
A long and narrow emitting device that emits light using a high-frequency electromagnetic field, and can be suitably used for document reading devices in office equipment such as
It is an object of the present invention to provide a lighting device equipped with an rL tube that has high brightness and a long life without uneven illumination.

Question + 1 - 1 - Description for fortune-telling [The purpose is coupled with the lighting device according to the present invention. Briefly, the present invention provides an elongated discharge tube that emits light by a high-frequency electromagnetic field, a coiled electrode that is divided into a plurality of pieces along the longitudinal direction of the discharge tube, and a coiled electrode that is divided into a plurality of pieces along the longitudinal direction of the discharge tube. a high-frequency applying means for applying a high-frequency electromagnetic field to the discharge tube through the coil-shaped electrode; Vl 11 means to control and J14
In a preferred embodiment of the present invention, which is a lighting device characterized by , and is controlled according to the amount of light from the light detection means that detects the light interval of the discharge tube.

Scale 3 Next, the illumination 921 according to the present invention will be described in more detail with reference to the drawings.

Referring to FIG. 1, one embodiment of the lighting device according to the present invention is shown. In this embodiment, the configuration of the discharge tube 1 of the lighting device 100A is similar to the discharge tube 1 described in connection with FIG. Yes, and to give a more specific example, usually,
The discharge tube has an elongated shape with a diameter of 5 to 30 mm and a length of 300 mm. In this case, several T of Ar is applied inside the discharge tube.
According to the present invention, a plurality of coils, in this example, 2 to 8 coils, are formed on the outer periphery of the radiator along the longitudinal direction. Shape electrodes 2a, 2b, . . . 2n are arranged. Each coiled electrode 2a to 2n is typically, but not limited to, one of the discharge tubes 1 as shown in FIG.
Each of the coiled electrodes 2a to 2n is constructed by winding several turns of an insulating coated conductor over approximately half the circumference of the discharge tube, and generally has an arbitrary configuration depending on the size and shape of the discharge tube. is connected in parallel to the high frequency applying means 3 similar to that explained in connection with the
The frequency is 8MHz-10MHz, the voltage is 200V or more at VPP, and the duty ratio of high-frequency pulse is 5 to 90.
% high frequency voltage is applied to achieve good lighting. However, according to the research conducted by the present inventors, when the same power is supplied to all the coiled electrodes 2a to 2n, luminescent clay along the longitudinal direction of the discharge tube is generated as shown in graph B of FIG. It was found that it was non-uniform.

According to the invention, different electric power is supplied to each coiled electrode 2a-2n. Further, as shown in FIG. 1, the illumination device 100A of the present invention has a control means 200 for supplying different power to each of the coiled electrodes 2a to 2n, In this embodiment, 200 is a switching element 2゜1 (201a to 201n) which is connected in series to the coil-shaped coils 2a to 2n and controls the high frequency power supplied from the high frequency applying means 3;
The switch elements 201a to 201n are turned ON10F.
Switch element driving means 202 (
202a to 202n) and a signal processing device 203. The signal processing device 22203 is a light detection means that converts the output from the sensor 204 (204a to 204n) disposed near the discharge tube 1 and detects the emission ridge from the discharge tube 1 into a voltage value. It functions to receive and process the signal from 205 and send a control signal to the switch element driving means 2.2.

To explain further, according to the present invention, each coiled electrode 2a~
The high-frequency power from the high-frequency application #-stage 3 supplied to the high-frequency power source #2n increases in size at the electrode located at the end of the discharge tube l according to the supply power fluctuation signal transmitted from the control means 200. Then, it is controlled so that it becomes smaller. That is, at least one power variation factor of duty ratio, frequency, and voltage is input as a supply power variation signal to the switch elements 201a to 201n, and the power supply to each coiled electrode 2a to 2n is varied. When a duty ratio is adopted as a power fluctuation signal, the duty ratio is 95% for the coiled electrodes 2a and 2n at both ends of the discharge tube l, for example, as shown in FIG.
It was said that they were next to each other. For the lit electrode 2b, the duty ratio is set to 90%, and for the electrode 2d at the center of the discharge tube, the duty ratio is set to 80%. As a result of controlling the power supplied to each coiled electrode 2a to 2n in this way,
As shown in FIG. 4, the amount of light emitted from the discharge tube 1 increases as shown in FIG. The amount of emitted light can be made uniform along the longitudinal direction of the light source.

Further, according to the above embodiment of the present invention, the magnitude of the supply power fluctuation signal transmitted from the control means 200 depends on the signals from the sensors 204a to 204n and the light amount detection means 205 arranged adjacent to the discharge tube l. It is automatically controlled to obtain a uniform luminescence distribution in the longitudinal direction of the discharge tube, or in some cases to obtain a desired luminescence distribution that is not uniform. In the example of
By measuring the luminescence distribution of the discharge tube l in advance, the magnitude of the supply power fluctuation signal input from the control means 200 to the switch element 201 can be fixed to the desired design without providing the sensor 204 and the light amount detection means 205. It is also possible to set it to a value.

Furthermore, in the embodiment described above, the high frequency application means 3 are provided in one piece, but it is also possible to arrange one for each coiled electrode. Furthermore, in the above explanation, the number of turns of each coiled electrode is the same, but increasing the number of turns of each coil at the end of the discharge tube also increases the magnetic flux of the coil electrode and increases the amount of light emitted. effective.

The lighting device according to the present invention configured as described above can be suitably used not only for general illumination but also particularly for document reading devices of office equipment such as electrophotographic copying devices. . Equipped with an elongated discharge tube, uniform in the longitudinal direction of the discharge tube,
Alternatively, it has the features of high brightness and long life that can provide any emission distribution as desired. Further, it is possible to improve the reduction in light intensity at the end of the discharge tube, and the effective length of the discharge tube can be increased, which is also effective in downsizing the lighting device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of a lighting device according to the present invention. FIG. 2 is a schematic perspective view showing the structure of a discharge tube and a coiled electrode. FIG. 3 is a chart showing an example of a power fluctuation signal (duty ratio) transmitted from the control means. FIG. 4 is a graph showing the emitted light φ along the length direction of the discharge tube of the conventional lighting device and the lighting device of the present invention. FIG. 5 is a schematic configuration diagram of a conventional lighting device. FIG. 6 is a block diagram showing an example of high frequency application means. l: release'+[tubes 2a to 2n: coiled electrode 3: high frequency application means 200: control-L stage 201: switch element 202: switch element driving means 203: signal processing means 204: sensor 205: light 711 detection stage Agent Patent Attorney Akira Kurahashi Figure 2 Figure 3 a b : d ; = n

Claims (1)

[Claims] 1) An elongated discharge tube that emits light by a high-frequency electromagnetic field;
A coiled electrode divided into a plurality of pieces arranged along the longitudinal direction of the discharge tube, a high frequency applying means for applying a high frequency electromagnetic field to the discharge tube via each of the coiled electrodes, and each of the coils. It is characterized by comprising a control means for transmitting a power fluctuation signal supplied to each coiled electrode in order to vary the magnitude of power supplied to each coiled electrode, and controlling the magnitude of power supplied to each coiled electrode. lighting equipment. 2) The lighting device according to claim 1, wherein the supplied power fluctuation signal is at least one of a duty ratio, frequency, or voltage fluctuation signal of the supplied power. 3) The lighting device according to claim 1 or 2, wherein the control means is controlled according to the amount of light from a light amount detection means that detects the amount of light from the discharge tube. 4) The illumination device according to claim 1, 2 or 3, wherein each coiled electrode is connected in parallel to one high frequency application means. 4) The lighting device according to claim 1, 2 or 3, wherein the high frequency application means is provided for each coiled electrode.