JPS6358797A - Lighting device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an illumination device that can be used for various purposes, and particularly to a document reading device that illuminates a document and reads a document image in office equipment, etc. In other words, the present invention relates to an illumination device that can be suitably used as an exposure means or the like. Hereinafter, in this specification, the present invention will mainly be described in connection with a document reading device for office equipment; however, the application of the illumination device according to the present invention is not limited to this device. .

'-1 of 1! -7 and 131 Conventionally, long sheets (
As elongated light sources, elongated fluorescent lamps, halogen lamps, etc. are frequently used.

Fluorescent lamps emit a small amount of light and are usually used as illuminating devices for low-speed office equipment.
If the power supply is increased to improve the brightness (light emitted light value), the internal filament installed inside the fluorescent tube will melt, so there is a limit to the increase in the power supply, and in reality, it is not suitable for lighting for high-speed office equipment. It is unsuitable as a device.

On the other hand, halogen lamps emit a large amount of light and are used for high-speed office equipment, but they emit more light in the infrared range than the visible light range required for reading documents in office equipment. Not only is the luminous efficiency low, but the heat generated by such wavelengths is large, and in order to reduce this heat generation effect, a cooling device, especially a large cooling bag, is required, making office equipment smaller and cheaper. It cannot be said that the lighting 92t is desirable today.

The present applicant has proposed an elongated illumination device which solves the drawbacks of conventional fluorescent lamps and halogen lamps and is suitable not only for general illumination but also particularly for document reading equipment in office equipment (patent application As shown in FIG. 3, the illumination device 100 includes a discharge tube 1 that emits light by a high-frequency electromagnetic field, and a plurality of coils arranged along the longitudinal direction of the elongated discharge tube l. The discharge tube 1 includes an electrode 2 wound around the outer wall of the discharge tube 1, and a high frequency applying means 3 for supplying high frequency power to the electrode. Alternatively, as shown in FIG. 4, in place of the coiled electrode 2 shown in FIG. 3, the illumination device 100 may include a material with low oxidation, such as copper or stainless steel, at or near both ends of the elongated discharge tube l. An annular plate electrode 2a made of a conductor such as the like is used. Although the electrode can be provided slightly apart from the outer wall of the discharge tube, it is usually preferable to provide the electrode in close contact with the outer wall of the discharge tube because the power loss applied to the discharge tube is small.

To explain further, in FIGS. 3 and 4, the discharge tube l
is usually formed by coating a phosphor inside a long and narrow glass tube made of soda glass or pyrex glass, and the inside of the discharge tube is filled with a discharge initiating material such as mercury and an inert gas such as Ar. . The electrode 2.2a includes:
A high frequency voltage is applied by the high frequency applying means 3. The high frequency applying means 3 may have any configuration, but for example, as illustrated in FIG. an amplification base 6 that amplifies the high frequency voltage from 5 to a desired voltage; and a discharge tube l
LC coupler 7 for matching the impedance of the LC coupler 7.

The electrode 2.
When a high frequency voltage is applied to 2a, the mercury gas within 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 light range.

In the lighting device shown in FIGS. 3 to 5 above, the electrode 2.2a is provided outside the discharge tube, and unlike conventional fluorescent lamps and halogen lamps, the lighting device does not have a filament inside the discharge tube. First, 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 apply a large amount of power to the electrodes, making it possible to increase the amount of light. In addition, such lighting devices do not generate high heat like conventional halogen lamps and have extremely good luminous efficiency, so when used in 1-hour office equipment, only a small cooling device is required. , there is an advantage that there is no need to specially prepare the cooling bag 2 in some cases. Furthermore, since the discharge tube can be formed into a long length, such an illumination device has the feature that it is extremely effective, especially when used as a document reading device, since uneven illumination does not occur across the width of the document.

The above-mentioned Teru'Jl'A position has various advantages as mentioned above, but according to the research experiments of the wood inventors, (1) the third
As shown in the figure, a coiled electrode 2 is used, high frequency power is supplied to the electrode, an electromagnetic field is generated by the electrode, and a strong electromagnetic field is applied to the discharge tube to light the discharge tube. did. So-called high i! Although the illumination device 21100 using the magnetic field application type coiled electrode 2 can achieve high brightness, the discharge of the discharge tube is greatly affected by fluctuations in load impedance.

Furthermore, the energy required to excite mercury, etc. in the discharge tube varies greatly depending on the temperature of the mercury, and there is a problem that stable lighting cannot be obtained.In other words, the initial lighting is very unstable, and the discharge tube may not light at all, or it may not turn on for a long time. Phenomena such as only half of the tube being illuminated may occur, and furthermore, it may take a considerable amount of time, for example 6 to 10 seconds, to turn on the tube. 2) In a lighting device using a so-called voltage application type electrode that applies a high voltage to an annular plate electrode to generate a discharge in the discharge tube as shown in FIG. 4, discharge of the discharge tube can be easily achieved. However, it was found that it has the disadvantage that it is difficult to obtain high brightness.

As a result of conducting many research experiments to solve these problems, the present inventors installed a voltage application type 'electrode and an electromagnetic field application type coiled electrode side by side in a discharge tube, and the power to both electrodes was set up in parallel. It has been found that the conventional problems can be solved by controlling the supply timing of the discharge tube according to the temperature of the discharge tube.

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

2'1'1'1 Brush J An object of the present invention is to provide a high-intensity, long-life lighting device that can achieve stable and reliable initial lighting.

Another object of the present invention is to provide a discharge tube with a preferably elongated shape that emits light by a high-frequency electromagnetic field, which can be suitably used in a document reading device of office equipment such as an electrophotographic copying device, and which is stable. It is an object of the present invention to provide a lighting device which can achieve reliable initial lighting in an extremely short period of time, and has a short rise time, high brightness, and a long life.

3. For aging - The above object is achieved by the lighting device according to the present invention. In summary, the present invention provides a discharge tube that emits light by a high-frequency electromagnetic field, a voltage application type electrode disposed at or near both external ends of the discharge tube, and a voltage-applying electrode disposed outside the discharge tube. an electromagnetic field application type coiled electrode; a high frequency application means for applying a high frequency electromagnetic field to the discharge tube via the voltage application type electrode and the electromagnetic field application type coiled electrode; A control means for controlling the supply timing of high frequency power from the high frequency applying means to the voltage applying type electrode and the electromagnetic field applying type coiled electrode in accordance with a signal from the temperature detecting means. This is a lighting device characterized by:

Next, the lighting device according to the present invention will be described in more detail with reference to the drawings.

Referring to FIG. 1, an illumination according to the present invention'! An embodiment with A is shown, and in this example, the discharge tube l and electrodes of the illumination device 100A are shown. , 2a have the same structure as the discharge tube l and electrode 2.2a described in connection with FIGS. 3 and 4. To give a more specific example, the discharge tube has a diameter of 5 to 3 mm and a length of 300 mm, and the inside of the discharge tube is filled with Artl-several Torr and Hg as a discharge initiator. In the produced discharge tube having the configuration shown in FIG. 1, the coiled electromagnetic field application type electrode 2 is supplied with a frequency of 8 MHz to 1OMH from the high frequency application means 3 during the normal lighting state.
2,? ! ! A high frequency voltage with a voltage of 200 V or more at VPP and a high frequency pulse duty ratio of 5 to 90% is applied to achieve good lighting.

However, when such a lighting device is used, at the time of initial lighting, the same voltage VPP as in the lighting state is applied to the main electrode 2.
If 8MHz to 10MHz is supplied at the same time, only half of the discharge tube will light up, and it will not be possible to light it up completely.

According to the present invention, as shown in FIG. J442a is installed. The plate electrode 2a is made of a conductive material that is less likely to be oxidized, such as copper or stainless steel. The plate electrode 2
Although a can be provided slightly apart from the outer wall of the discharge tube, it is usually preferable to provide it in close contact with the outer wall of the 7It tube because the power loss applied to the discharge tube is smaller.

As illustrated in FIG. 1, the high frequency application means 3 for supplying high frequency power to said electrode 2.2a are the same as the means described in connection with FIG. 5, but according to the invention 1
When lighting, first, power is supplied to the plate-shaped electrode 2a, the plate-shaped electrode generates a discharge to the extent that the temperature of the tube wall of the discharge tube is set to a predetermined temperature, and then the temperature of the tube wall of the discharge tube is set at a predetermined timing according to the temperature of the tube wall of the discharge tube. In order to supply power to the coiled electrode 2 at the electrode ? , 2a is provided.

According to this embodiment, the control means 20 includes, for example, a microprocessor (not shown) and a switching element that is driven and controlled by the microprocessor and switches the power supply between the electrodes 2.2a. 22, which is also driven and controlled by the microprocessor 21, and the electrodes 2, 2
A power fluctuation factor driving means (not shown) is provided which acts on the high frequency oscillation circuit 3 and the like to vary the magnitude of the power supplied to the circuit a, and drives and controls the power fluctuation factor of the circuit.

Further, according to the present invention, a temperature detection means 24 is provided which is in contact with the discharge tube and detects the tube wall temperature of the tube 1 and sends a signal to the microprocessor of the control means 20.

In the illumination device 100A having the above configuration, the switching element 22 is driven by the microprocessor of the control means 20, and the switching element 22 is driven by the microprocessor of the control means 20 in order to put the plate-shaped electrode, that is, the voltage application type electrode 2a, into the operating state. Contacts C and a are connected. At the same time, the control means 20 uses a microprocessor to drive the power variation factor driving means to control the electrode 2a.
It acts on the high frequency application means 3, for example, the high frequency oscillation circuit 4, so that a predetermined power is supplied to the high frequency applying means 3, for example, the high frequency oscillation circuit 4. As a result, preliminary high-frequency power is supplied to the discharge tube prior to lighting, and the atoms and electrons of mercury and Ar gas within the discharge tube repeat vibrations and enter a preliminary excited state, raising the temperature of the discharge tube to a certain temperature. The state is immediately before the start of discharge.

Next, when the temperature of the discharge tube 1 is detected by the temperature detection means 24, the signal is transmitted to the control means 20. The control means 20 operates as shown in FIG. At this point, contacts C and a are opened, and contacts c and b are connected. At the same time, the control means 20 operates the high frequency application means 3, that is, the high frequency oscillation circuit 4 in this embodiment, so that a predetermined power for lighting the discharge tube is supplied to the coiled electrode 2. As a result, the mercury and Ar, which were previously in an excited state, are brought into a completely excited state, and the discharge tube 1 immediately lights up, achieving high-intensity light emission. - As understood from the explanation above, when power is supplied to the coiled electrode 2, the supply of power to the plate electrode 2a is stopped;
It is also possible to continue supplying power to a for a predetermined period of time.

Figure 2 shows the relationship between the temperature of the wall of the discharge tube and the time for energizing the plate electrode 2a, that is, the switching timing. is understood.

For example, as mentioned above, if the diameter of the discharge tube is 5 to 30 mm and the length is 300 mm, several To
In a lighting device using a discharge tube l having the configuration shown in FIG. 1, which is manufactured by sealing Hg as a discharge initiating material, the high frequency applying means 3 applies a frequency of 10 Hz to the coiled electrode 2 during normal lighting conditions. −10” Hz, 'il
j Pressure is at VPP.

From OV, high-frequency power with a high-frequency pulse duty ratio of 5 to 90% is applied, but to the plate-shaped J42a, high-frequency power is applied from the high-frequency applying means 3 at a frequency of 10 Hz to 10 Hz and a voltage of 20 V or more at VPP. Good lighting with high rlra is achieved by applying high frequency power with a high frequency pulse duty ratio of 5 to 90%. That is, in the present invention, it is preferable that the main power supplied to the sub-electrode 2a be 10 to 50% of the power supplied to the main electrode 2.

When this illumination device is used in a document reading device such as a copying machine, a normal copying operation is performed after the illumination device is turned on as described above. When the copying operation is completed, the high frequency application means is also turned off. If a copying operation is to be performed continuously, the illumination device supplies preliminary power to the plate-shaped electrode and then supplies power to the coil-shaped electrode as before. It is possible to supply power and light up the discharge tube, but if the discharge tube is turned off for a short time, such as during continuous copying, the discharge tube may be turned on.
The temperature of the tube wall of the tube decreases little, and the step of supplying power to the plate electrodes can be omitted or extremely reduced.

The power fluctuation factor driving means of the control means 20 can be configured to control any one of the high frequency voltage, duty ratio, frequency, or any combination of α in the high frequency oscillation circuit 4.

In the explanation in H, power is supplied to the coil electrode 2 and the plate electrode 2a using one high frequency application means 3, and by controlling the power fluctuation factor of the means, 241 types of high frequency power are generated. Although it has been explained that two kinds of high frequency applying means are provided for the coil electrode and the plate electrode, and the configuration is such that a predetermined power is supplied to each electrode by switching with a switching element. It is also a moat.

The lighting device according to the present invention configured as described above is a general lighting device. Of course, it can be particularly suitably used in a document reading device of a TA device such as an electrophotographic copying machine, etc.
It is preferably equipped with a discharge tube having an elongated shape, and has the features of being able to achieve stable and reliable initial lighting, shortening the lighting time, and having high brightness and long life.

[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 graph showing the relationship between the temperature of the tube wall of the discharge tube and the time during which current is applied to the voltage-applying electrode. 3 and 4 are schematic configuration diagrams of conventional lighting devices. FIG. 5 is a block diagram showing an example of conventional high frequency l adding means. l: Radiation tube 11 2: High electromagnetic field application type electrode 2a: Voltage application type electrode 3: High frequency application means 20 Control means 22 Niswitching element 24: Temperature detection means Avoidance mode 7 Fig. 1 Figure Tube temperature T ('C)

Claims (1)

[Scope of Claims] 1) A discharge tube that emits light by a high-frequency electromagnetic field, a voltage application type electrode disposed at or close to both external ends of the discharge tube, and a voltage-applying electrode disposed outside the discharge tube. a high-frequency applying means for applying a high-frequency electromagnetic field to the discharge tube via the voltage-applying electrode and the electromagnetic field-applying coiled electrode, and controlling the tube wall temperature of the discharge tube. A control means for controlling the supply timing of high frequency power from the high frequency applying means to the voltage applying type electrode and the electromagnetic field applying type coiled electrode in accordance with a signal from the temperature detecting means. A lighting device characterized by: 2) The lighting device according to claim 1, wherein the high frequency power supplied to the voltage application type electrode is 10 to 50% of the high frequency power supplied to the high electromagnetic field application type coiled electrode. 3) The lighting device according to claim 1 or 2, wherein the high-frequency power to the voltage application type electrode is stopped after the discharge tube is lit.