JPS62150695A - Lighting apparatus - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application of the Invention) The present invention relates to a lighting device in which light can be adjusted to a predetermined or desired value. More specifically, the present invention relates to a lighting device that can be used for general lighting as well as business machines such as image forming devices.

(Background Art) Conventionally, fluorescent lamps and halogen lamps have been widely used as light sources for lighting devices.

Fluorescent lamps and halogen lamps cannot achieve high brightness because the filament breaks when high power is applied. Furthermore, there was a problem that the filament inside the discharge tube deteriorated due to the gas, making it impossible to obtain a long life.

In view of this problem, a light source that does not have a filament inside the discharge tube and emits light by applying high frequency waves has recently been considered.

However, it has been confirmed that with such a light source that does not have a filament inside the discharge tube, it is very difficult to adjust the amount of light to a predetermined or desired value.

In other words, when the high-frequency voltage applied to the discharge tube is changed, the matching relationship between the discharge tube side and the high-frequency application side also changes, making the light amount unstable, and in order to adjust this, extremely high voltage is required. Precision and high-level technology are required.

In addition, the method of changing the impact coefficient by turning off the high-frequency application device on and off generates a transient high voltage, which not only accelerates the deterioration of the device, but also causes the amount of light to become unstable due to the noise generated by turning on and off. There's a problem.

(Objective) The present invention solves the above problems and provides a lighting device that not only has high brightness and long life, but also can stably adjust the amount of light to a predetermined or desired value.

(Summary of the Invention) To achieve the above objects, the present invention provides a discharge tube that irradiates visible light with a high-frequency electromagnetic field, an electrode provided in contact with or near the outer wall of the discharge tube, and a high-frequency electromagnetic field applied to the electrode. A lighting device comprising a high frequency applying means for applying a high frequency wave, the high frequency applying means having a high frequency generating means for generating a high frequency wave, and an impedance control means for controlling an impedance of the high frequency generating means. be.

(Example) FIG. 7 is a sectional view of an image forming apparatus to which the illumination device of the present invention can be applied.

In the figure, 7 is a document placement cover, 22 is an illumination device of the present invention,
23 is a first mirror, 24 is a second mirror, 25 is an in-mirror lens, and 26 is a third mirror, which project an optical image onto the photosensitive drum 27 by subjecting the document to slit exposure. Reference numeral 28 denotes primary and secondary chargers for forming a latent image on a photoreceptor having an insulating layer on its surface, which are integrally constructed here. Note that the above optical image is exposed simultaneously with the secondary charging. Furthermore, an electrostatic latent image is formed on the surface of the drum 27 by the full-surface exposure lamp 29. 30 is a developing device for visualizing the latent image thus formed.

- On the other hand, the cut paper as a recording material in the paper feed stacker 31 is fed by a pickup roller 32, passed through a paper feed guide 33, and the visible image on the drum 27 is transferred by a transfer charger 34, and then the paper is transferred to a transport section. 35, the sheet is converted into a fixed image in a fixing device 36, and is discharged to a sheet discharge stacker 37.

The developer remaining on the drum 27 during the transfer process is removed by the cleaner 3.
After being removed in step 8, the drum 27 is neutralized by a static eliminator 39 and a static eliminator 4° to erase the electric image remaining on the photoreceptor, and returns to its original state. In addition, 41 is a blank exposure lamp which forms a latent image bright portion in order to prevent development from being performed when the optical system is backed up. In the figure, E, E
2, E3. indicates the exposed area.

Of course, in this embodiment, it is also possible to apply the illumination device of the present invention to the static elimination lamp 4o and the blank exposure lamp 41 in addition to the document illumination device.

Next, the lighting device of the present invention will be explained.

FIG. 1 is a schematic diagram of a lighting device 1 of the present invention.

In the figure, 2 is a discharge tube with mercury and inert gas sealed inside.
The inner walls are coated with fluorescent material. 3 is a power supply line for supplying high frequency power to the electrode 4. Reference numeral 5 denotes a slit portion which is not coated with phosphor, and is a region through which visible light inside the discharge tube passes. It is necessary to give directionality to the slit, and this configuration is effective for this slit portion.

Furthermore, since there is no filament inside the discharge tube, high power can be applied, and the discharge tube has high brightness and long life.

6 is a DC power supply, 15 is a high frequency oscillation unit, and in this embodiment, 10
Oscillates at MHz. Reference numeral 16 denotes an amplifying section, and 17 an impedance matching section, which includes a variable high-voltage capacitor 18 and adjusts the impedance to an optimum value according to the load impedance.

9 is a light amount sensor, 10 is a light amount detection section, 11 is an integrator, 12
13 is an A/D conversion section, 13 is a control section, and 19 is a motor drive section (for example, a stepping motor) having a small motor.

Next, the operation shown in FIG. 3 will be explained.

Reference numeral 15 denotes a sine wave oscillation section which oscillates at a high frequency of, for example, 10 MHz, and 16 amplifies the voltage thereof.

The amplified high-frequency voltage is generated by supplying high-frequency power to the electrode 4 via the impedance matching section 17 and the low-loss transmission line 3, thereby exciting the mercury gas inside the discharge tube 5. Ultraviolet light is converted into visible light by a phosphor.

Next, a feedback system for keeping the amount of light emitted constant will be explained.

9, the integrator 1
1, the signal is roughly converted into a digital signal via an A/D converter, and the signal is supplied to the controller 13.

The light amount data supplied to the control unit 13 is stored in advance in the internal R.
It is compared with the appropriate light amount value data stored in the OM 20 in the arithmetic unit 21, and data is determined according to the difference.

The data corresponding to the difference is outputted from the control section 13, supplied to the small stepping motor via the motor drive section 19, rotated by the number of pulses corresponding to the data, and the capacitance of the high voltage capacitor inside the impedance matching section 17. change. In other words, the amount of light is kept constant by supplying pulses corresponding to the insufficient or excessive amount of light from the control section to the motor and changing the output impedance. FIG. 2 shows changes in the current flowing through the fluorescent lamp when the capacitance of the high voltage capacitor 18 in this embodiment is changed and the output impedance of the high frequency applying means 8 is changed.

It has been experimentally found that the tube current changes greatly with respect to the output impedance, and changes almost linearly.

It can be seen that it is possible to control the amount of light by utilizing the change in the discharge tube current by changing the output impedance of the impedance matching section of the output stage of the high frequency application means 8 in this way. As shown in Fig. 3, for example, if the load impedance seen from the high frequency application means side of the discharge tube is Zffl, and the impedance on the high frequency application means side seen from the load side is Za2, then the discharge tube serving as the load Z can supply maximum power to the side. ! = When ZQ2. At this time, the brightness is at its maximum, and the brightness decreases as it deviates from this point. Therefore, the brightness can be freely selected based on the relationship between ZQL and Za2.

FIG. 4 shows the change in the voltage conversion value of the light amount obtained from the sensor 9 via the light amount detection circuit 13, which is the amount of light emitted from the discharge tube when the impedance Za2 on the high frequency application means side is changed by the output capacitor of the impedance matching section. FIG. In this way, it is possible to control the amount of light by changing the output impedance on the side of the high frequency application means.

FIG. 5 is a flowchart showing a sequence for keeping the amount of light constant at a predetermined value. The power is turned on at 5TEPI, and first, at 5TEP2, appropriate light amount data (determined in advance by experiment) stored in the ROM is taken in.

5Import the light amount data from the current light source with TEP35
Compare with the appropriate light amount data in TEP4 and if they do not match (S
At TEP5), a pulse is sent to the motor and the amount of light is changed by changing the capacity of the variable capacitor in the impedance matching section.

If they match, stop the sending pulse with 5TEP6 and 5TE
Returns at P7.

In this way, it is possible to keep the light amount of the lighting device constant by detecting the light amount with the light amount detection means, feeding it back, and controlling the output of the high frequency application means.

Further, it is also possible to change the light amount to a desired value by inputting a signal (not shown) to the motor drive section 19 to change the light amount to a desired value and controlling the variable capacitor.

FIG. 6 shows another embodiment of the invention. In the drawings, the same reference numerals are given to the same members.

The power supply line is connected to the impedance matching section 17 as in FIG.

Here, the electrode 4 is wound in a coil shape a plurality of times in the longitudinal direction of the tubular light source. The rigid electrode shape is a more preferable embodiment, since it is possible to supply higher radio frequency power and obtain even higher luminance than in the case of the electrode shape of the embodiment shown in FIG.

Next, the high frequency used in the present invention will be described.

In the lighting device of this embodiment, the amount of light changes depending on the frequency. When we experimentally investigated the frequency to improve brightness, power efficiency, etc., we found that it emits light at a frequency of several KHz or more, but 10'' to 108 Hz is preferable.

In this embodiment, a variable capacitor was used to change the impedance of the high frequency application means, but the present invention is not limited to this, and may also use a variable resistor or both, and further change the impedance electronically. It's a good thing.

Further, it is clear that the present invention is not limited to a tubular discharge tube, but may be a spherical discharge tube, a flat discharge tube, or the like.

Further, although the electrode may be located away from the discharge tube, it is preferable that the electrode be closer to the discharge tube, especially in contact with the discharge tube.

(Effects) As described above, the present invention has higher brightness and longer life than conventional fluorescent lamps and halogen lamps, and can stably adjust the amount of light to a predetermined or desired value. be.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of an embodiment of the present invention. 3 and 4 are explanatory diagrams of the present invention, FIG. 5 is a flowchart showing the sequence of the present invention, FIG. 6 is a diagram showing another embodiment of the present invention, and FIG. 7 is a lighting device of the present invention. 1 is a cross-sectional view of an image forming apparatus to which the invention is applicable. In the figure, 2 is a discharge tube, 4 is an electrode, 8 is a high frequency application means, 1
8 is a variable capacitor.

Claims (6)

[Claims] (1) It has a discharge tube that irradiates visible light with a high-frequency electromagnetic field, an electrode provided in contact with or near the outer wall of the discharge tube, and a high-frequency application means for applying high frequency to the electrode, A lighting device characterized in that the high-frequency applying means includes a high-frequency generating means for generating a high-frequency wave and an impedance control means for controlling the impedance of the high-frequency generating means. (2) Claim (1) characterized in that the impedance control means has a variable capacitance or a variable resistance, and controls the value of the variable capacitance or variable resistance.
The lighting device described in Section 1. (3) According to claim (1) or (2), the discharge tube is tubular and has a slit portion extending in its longitudinal direction and not coated with a phosphor. Lighting device as described. (4) The lighting device according to claim (3), wherein the lighting device is used in an image forming apparatus. (5) Claims (1) to (4) characterized in that the impedance control means controls the impedance of the high frequency generation means according to the amount of light from the discharge tube.
The lighting device described in any of paragraphs. (6) The lighting device according to any one of claims (1) to (5), wherein the high frequency is 10^6 to 10^8 Hz.