JPS62154450A - Lighting system - Google Patents

Abstract

PURPOSE:To make a lighting system have high luminance, long service life and reach the specified luminous energy in a short time as well as to improve its builtup characteristic, by installing such a device that heats a discharge tube before its discharge. CONSTITUTION:An electrode 11 for impressing a high frequency electromagnetic field exists in the inner part of a discharge tube connected to a high frequency lamp source, covering a lamp circumferential surface at the edge side in the longitudinal direction of a lamp. Before lighting a lighting system 22, during a posture of standing by, both switches 1 and 2 come into contact with a terminal A, and a heating power source 8 heats the electrode 11 whereby gas inside the discharge tube is heated as far as about 30 deg.C in temperature. When these switches 1 and 2 come into contact with a terminal B and high frequency is impressed in the electrode, mercury gas inside the discharge tube comes into a state of being excited by a high frequency electric fields, and the generated ultraviolet rays are converted into visible rays by a phosphor. Since gas inside the discharge tube is heated and brought into a state of being easily excitable during a period of standing by, built-up time gets off with a short span.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field of the Invention) The present invention relates to a lighting device that can be applied from general lighting to office machines such as document reading devices.

(Background Art) Conventionally, lighting devices such as document reading devices use light sources such as fluorescent lamps and halogen lamps.

However, in recent years, there has been a demand for a light source with high brightness and long life in order to more reliably obtain document information.

Based on such requirements, light sources that do not have a filament for discharging inside the light source have been considered.

FIG. 17 is a cross-sectional view of this light source. Reference numeral 4 denotes a lamp. The inner surface of the lamp 4 is coated with a phosphor 3, and the interior thereof is filled with mercury and an inert gas. A protruding cylindrical portion 7 is formed in the lamp 4 so as to include the transformer 2. The transformer 2 consists of a core 6 and a coil 5, and both ends of the coil 5 wound around the core 6 are connected to a high frequency lamp power supply l.

When a high frequency voltage is applied to the coil 5 from the high frequency lamp power source 1, a high frequency electromagnetic field is generated around the coil 5. The electric energy of this electromagnetic field excites the mercury gas in the lamp 4, and the ultraviolet rays of the mercury caused by this excitation are converted into visible light by the phosphor 3 applied to the surface of the lamp 4.

In this configuration, energy is applied to the gas inside the lamp from the outside to cause it to discharge, so it takes a long time for the lamp to rise until it reaches a predetermined amount of light, and it requires less frequent on/off switching than in lighting devices such as document reading devices. It is not suitable for applications where it is desired to reach a predetermined amount of light in a short period of time due to a high amount of light. In addition, due to temperature unevenness within the lamp, it takes more time for the discharge state to become stable and for a stable luminescence distribution to occur.7IIt,$l (Purpose) The present invention solves the above problems. The present invention provides a lighting device that has high brightness, long life, reaches a predetermined amount of light in a short time, and has excellent start-up characteristics.

(Means for Solving the Problems) To achieve the above object, the present invention provides a discharge tube that generates visible light using a high frequency electromagnetic field;
Alternatively, it is an illumination device characterized by having an electrode provided nearby, a high frequency inlet/applying means for applying a high frequency to the electrode, and a heating means for heating the discharge tube before the discharge tube discharges.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the figures, the same members are given the same numbers.

FIG. 16 is a sectional view of an image forming apparatus equipped with a document reading section to which the illumination device of the present invention is applied.

Still another means includes a discharge tube that generates visible light by 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 that applies a high frequency to the electrode. This high frequency application means is characterized by having a first means for applying an output to the electrode that causes the discharge tube to discharge, and a second means for applying an output to the electrode that does not cause the discharge tube to discharge, thereby heating the discharge tube. It is a lighting device.

In the figure, 21 is a document placement cover, 22 is a document exposure device to which the illumination device of the present invention is applied, 23 is a first mirror, 24 is a second mirror, 25 is a lens mirror lens, and 26 is a third mirror. , an optical image is projected 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. 3
0 is a developing device for visualizing the latent image thus formed.

On the other hand, cut paper as a recording material in the paper feed star 2 car 31 is fed by a pickup roller 32, passed through a paper feed guide 33, and a visible image on the drum 27 is transferred by a transfer charger 34. 35, the sheet is converted into a fixed image by 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 a cleaner 38, and then removed from the drum 27 by an electricity remover 39 and an electricity remover lamp 40 in order to erase the electrical image remaining on the photoreceptor.
is removed and returns to its original state. Incidentally, reference numeral 41 denotes a blank exposure lamp which forms a bright portion of a latent image in order to prevent development from occurring when the optical system is backed up.

In the figure, E, E2, and E3 indicate exposed areas.

Of course, in this embodiment, the illumination device of the present invention can be used not only as the document illumination device but also as the static elimination lamp 40 and the blank exposure lamp 41.

Next, a lighting device according to an embodiment of the present invention will be described.

FIG. 1 is a simplified diagram showing one embodiment of the present invention.

In the figure, 1 indicates a high frequency lamp power supply, and 1
0 is an elongated discharge lamp, the glass is ordinary soda glass or pyrex glass, and the inner surface is coated with a predetermined phosphor. Furthermore, the discharge lamp is filled with mercury and an inert gas.

Reference numeral 11 denotes an electrode connected to a high-frequency lamp power source for applying a high-frequency electromagnetic field to the inside of the discharge tube, and covering the circumferential surface of the lamp on the longitudinal end side of the lamp. The material may be any ordinary conductor, but copper, stainless steel, etc., which are less prone to deterioration due to oxidation, are preferable.

Before the lighting device 22 is turned on, that is, during the stun/< Sw
, l and Sw,2 are in contact with terminal A, and heating power source 8
By heating the electrode 11, the gas inside the discharge tube is reduced to about 3
It is heated to 0°C.

When a lighting signal is added to this state, Sw, 1 and Sw
, 2 are in contact with terminal B, and a high frequency is applied to the electrodes. The mercury gas inside the discharge tube is brought into an excited state by the high-frequency electric field, and the generated ultraviolet rays are converted into visible light by the phosphor.

FIG. 2 is a block diagram illustrating the outline of this embodiment.

Input power is applied from the input power supply to the high frequency oscillation circuit to generate a high frequency, and then the voltage is amplified by the amplifier circuit and applied to the '1 pole via the transmission line.

According to this embodiment, since the gas in the discharge tube is heated during standby and kept in a state where it is easy to excite, the standby time can be shortened.

FIG. 3 shows another embodiment of the invention.

Here, the discharge tube is the same as that shown in FIG. 1, but the electrode is in contact with the discharge tube and is wound in a coil shape a plurality of times in the longitudinal direction of the discharge tube.

Hereinafter, the electrodes of the embodiments of the present invention will be explained using those shown in FIG. 1 and those shown in FIG. 3, but the electrodes are not limited to any shape in the embodiments, and either electrode shape may be used.

The coil-shaped electrode shown in FIG. 3 is preferable because it can supply a larger amount of power than the electrode having the shape shown in FIG. 1, and therefore can provide even higher brightness.

FIG. 4, FIG. 6, and FIG. 8 are block diagrams of different embodiments for explaining the outline of the embodiment of FIG. 3.

First, the embodiment shown in FIG. 4 will be explained. Input power is applied to the high frequency oscillation circuit from an input power source. The high frequency oscillator circuit is provided with a terminal a which outputs a high frequency wave with a voltage high enough to discharge the discharge tube via an amplifier circuit, and a terminal A which outputs the same frequency wave with a voltage high enough to discharge the discharge tube.

During standby, the amplifier circuit is in a conductive state when the terminals are connected, and a voltage sufficient to cause a discharge through the transmission path is applied to the electrodes.
The discharge tube does not discharge, the electrodes are heated, and the gas inside is in a state where it is easily excited at about 30°C.

When a lighting signal is input in this state, the terminal a and the amplifier circuit are brought into conduction by the switching means, a voltage sufficiently high to discharge the discharge tube is applied to the electrode, and the discharge tube enters the discharge state.

As shown in Figure 5, which shows the output applied to the electrodes, it is small during standby and large when turned on, and it is possible to switch between the heating state and the lighting state by changing the voltage state like this. be.

In this embodiment, as in the embodiments shown in FIGS. 6 and 8, which will be described later, the gas inside the discharge tube is in a state where it is easy to excite, so the rise time until discharge is short, and furthermore, the discharge is uniform throughout the length of the discharge tube. Since the heating is performed to a uniform temperature, there is no temperature unevenness in the longitudinal direction, and a uniform light emission distribution in the longitudinal direction can be obtained almost at the same time as discharge, which is particularly preferable in a document reading device.

Another embodiment will be described with reference to the block diagram of FIG.

During standby, a sufficiently low frequency output is applied to the electrodes through terminal d, which does not cause discharge, and the discharge tube is in a heated state (approximately 3
0°C), and when a lighting signal is input in this state 4, the switching means makes terminal C conductive, and an output with a frequency high enough to discharge the discharge tube is applied to the electrode. This causes the discharge tube to turn on.

According to this embodiment, the output voltage used for preheating is set high in order to control the discharge by frequency.

This increases the heating capacity.

As shown in FIG. 7, which shows the output applied to the electrodes, it is possible to switch between the heating state and the discharging state by setting the frequency to be sufficiently lower during preheating than during lighting.

Another embodiment will be described with reference to the block diagram of FIG.

During preheating, a low voltage is input from the input power source to the voltage controlled oscillator. Here, the voltage controlled oscillator has an output frequency that changes as the input voltage changes, and can control both the frequency and voltage.

When a lighting signal is input, a high voltage is input from the input power source to the voltage controlled oscillator, and an output with a sufficiently high voltage and high frequency is applied to the electrodes to discharge the discharge tube.
The discharge tube enters a discharge state.

FIG. 9 shows the output applied to the electrodes.

In this way, by lowering both the voltage and the frequency during preheating, it is possible to further ensure that no discharge occurs during preheating.

Further, according to the configuration shown in FIG. 3, there is no need to provide a special power source, and the cost and size can be reduced, which is preferable.

FIG. 10 is a simplified diagram of yet another embodiment.

A filament is provided at the end of the discharge tube, and during preheating, a current is applied to the filament by a filament heating power source 9 to an extent that the discharge tube does not discharge.

When the lighting signal is input, the filament power source 13 is brought into conduction by the switching means 9, and a current sufficient to discharge the discharge tube is applied to the filament, and the discharge tube is discharged.
Therefore, the filament power source 13 is turned off and the high frequency lamp power source is turned on to apply high frequency to the electrodes to maintain the discharge state.

FIG. 11 shows a timing chart of this embodiment.

In this way, by having a filament inside the discharge tube, performing preheating with the filament, and further performing a rising discharge with the filament inside the discharge tube, the rise time until the discharge state is reached is further shortened.

Further, since the filament is in an off state in the discharge state, the filament is not easily deteriorated and has a long life.

FIG. 12 is a simplified diagram of yet another embodiment.

This embodiment does not have a filament heating power source, and the filament power source 13 serves both heating and rising discharge.

FIG. 13 is a block diagram illustrating the outline of this embodiment.

The filament power supply is provided with a terminal e that outputs a current sufficient to discharge the discharge tube, and a terminal f that outputs a current sufficient to not discharge the discharge tube.

During standby, a low current that does not cause the discharge tube to discharge is applied from the terminal f to the filament to preheat it.

When a lighting signal is input, the switching means brings the filament into conduction with the terminal e, and a current sufficient to discharge the discharge tube is applied to the filament, causing the filament to rise and discharge. When the discharge state is reached, the filament power source is turned off and the discharge state is maintained by the high frequency lamp source.

Like the embodiment shown in FIG. 10, this embodiment is also preferable because it has a short startup time and does not require a special power source.

Next, the preheating temperature will be explained using FIG. 14. The horizontal axis shows the temperature of the discharge tube, and the vertical axis shows the rise time. Moreover, this result was measured based on the example shown in FIG.

As can be seen from the figure, the rise time is shortest near 30°C, and increases as the distance from this point increases. From this, it can be seen that preheating of 20° C. to 40° C. is preferable since the rise characteristics are excellent.

Ru.

FIG. 15 shows the effect of the present invention.

The solid line shows the rise characteristics without preheating, and the dashed line shows the rise characteristics with preheating (30'O).

It can be seen that when preheating is performed, the rise characteristic is significantly shortened to about 1/3.

It was also found that preheating quickly stabilized the discharge. This is thought to be due to the fact that fine temperature unevenness in the discharge tube was reduced by preheating.

Next, the high frequency used for discharge will be explained.

The inventors of the present invention carried out experiments with an eye toward improving brightness and power efficiency, and found that 106 to 108 Hz is preferable. Furthermore, in the embodiments shown in FIGS. 6 and 8, the frequency used for preheating is 10% in order to increase heating efficiency.
It has been found that 6H2 or less is preferable.

The present invention is not limited to the electrode shape of the embodiment, and any shape that allows a high frequency electromagnetic field to be applied to the discharge tube may be used.

Further, the electrode may be separated from the discharge tube, but it is preferable that the electrode be close to the discharge tube, and particularly preferably that it is in contact with the discharge tube.

(Effects) The lighting device of the present invention has excellent effects such as high brightness, long life, short start-up time, and easy to stabilize the amount of light.

[Brief explanation of drawings]

1 is a simplified diagram of one embodiment of the present invention; FIG. 2 is a block diagram illustrating the outline of the embodiment of FIG. 1; FIG. 3 is a simplified diagram of another embodiment of the present invention; 6 and 8 are different embodiments applied to FIG. 3, FIG. 5 is an explanatory diagram of the embodiment of FIG. 4, FIG. 7 is an explanatory diagram of the embodiment of FIG. 6, and FIG. 9 is an explanatory diagram of the embodiment of FIG. 8 is an explanatory diagram of the embodiment, FIG. 10 is a simplified diagram of yet another embodiment of the present invention, and FIG. 11 is a timing chart of the embodiment of FIG. FIG. 12 is a simplified diagram of yet another embodiment of the present invention, FIG. 13 is a block diagram outlining the embodiment of FIG. 12, FIGS. 14 and 15 are explanatory diagrams of the present invention, and FIG. 16 17 is a sectional view of an image forming apparatus to which the present invention is applicable, and FIG. 17 is an explanatory diagram for comparison with the present invention. In the figure, 1 is a high frequency lamp power supply, 10 is a discharge tube, and 11 is an electrode. Figure 7 Figure 8 Figure 874 Yu゛°''J It) Zρ 3ρ a 6tr (')

Claims (1)

[Scope of Claims] 1. A discharge tube that generates visible light using a high-frequency electromagnetic field, an electrode provided in contact with or near the outer wall of the discharge tube, and high-frequency application means that applies a high frequency to the electrode. A lighting device comprising a heating means for heating a discharge tube before the discharge tube discharges. 2. The lighting device according to claim 1, wherein the discharge tube has an elongated shape, and the electrodes are provided extending in the longitudinal direction of the discharge tube. 3. The lighting device according to claim 1 or 2, wherein the heating means includes at least one filament provided inside the discharge tube and a filament power supply that applies a current to the filament. . 4. The lighting device according to any one of claims 1 to 3, wherein the heating means heats the inside of the discharge tube to a temperature of 20°C to 40°C. 5. The lighting device according to any one of claims 1 to 4, wherein the lighting device is used in a document reading device. 6. A discharge tube that generates visible light by 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 a high frequency to this electrode, and this high-frequency application The means includes a first means for applying an output to the electrode that causes the discharge tube to discharge, and a second means for applying an output to the electrode that does not cause the discharge tube to discharge, thereby heating the discharge tube. lighting equipment. 7. Claims characterized in that the high frequency applying means is capable of changing the output frequency, and the second means applies a lower frequency to the electrode than the frequency applied to the electrode by the first means. The lighting device according to item 6. 8. Claims characterized in that the high frequency application means is capable of changing the output voltage, and the second means applies a lower voltage to the electrodes than the voltage applied to the electrodes by the first means. The lighting device according to item 6 or 7, respectively. 9. The illumination according to any one of claims 6 to 8, wherein the discharge tube has an elongated shape, and the electrodes are provided extending in the longitudinal direction of the discharge tube. Device. 10. Claim 6, wherein the heating means heats the inside of the discharge tube to a temperature of 20°C to 40°C.
9. The lighting device according to any one of items 9 to 9. 11. The lighting device according to any one of claims 6 to 10, wherein the lighting device is used in a document reading device.