JPH0754398B2 - Original reading light source device - Google Patents

Description

The present invention relates to a document reading light source device used in an optical device such as a copying machine.

[Prior Art] Conventionally, electrodeless discharge lamps have been researched and developed in various places because of their features 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 type 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, the ultra-high-power straight-tube fluorescent lamp has the advantages of higher efficiency, less heat generation, and longer life than halogen bulbs, but on the contrary, there is a problem that sufficient light quantity cannot be obtained. Because the light output of the fluorescent lamp is
It is generally well known that the filament breaks when the filament electrode inside the lamp is lifted and a current exceeding the allowable current is flown.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 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 generated 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. 3 shows an original reading light source device using the electrodeless fluorescent lamp as described above. The electrodeless fluorescent lamp 1 has two straight tube portions which are parallel to each other, and both ends of the straight tube portion. A bulb 2 which communicates with each other in the vicinity to form a circulating discharge path, and an inductive coil 3 arranged along the circulating discharge path.
In addition, since it requires brightness and is a so-called aperture type, the reflection film 4 of titanium oxide or the like and the fluorescent body 5 are formed on the inner wall surface of the bulb 2, and a part of the inner wall surface is provided with an opening 6. The valve 2 is filled with a rare gas such as argon and a metal such as mercury. Further, the bulb 2 is provided with an exhaust pipe 7 in a part of the same discharge space and serves as the coldest portion of the lamp 1. The temperature of this coldest part, that is, the coldest point temperature determines the mercury vapor pressure in the lamp 1, and this mercury vapor pressure greatly affects the light output of the lamp 1. The relationship between the light output and the coldest spot temperature is as shown in FIG. 4, and it is well known that there is an optimum coldest spot temperature that maximizes the light output. In the figure, 8 is a high frequency (usually several MHz to several tens of MHz)
The oscillator circuit unit, 9 is a power supply unit, and 10 is a cable for transmitting high-frequency power from the high-frequency oscillator circuit unit 8 to the lamp 1.

FIG. 5 is a schematic configuration diagram showing an example in which the above-mentioned light source device is used in a copying machine. In the figure, 11 is a copying machine main body, 12 document table, 13 is a reflecting mirror, 14 is a photosensitive drum or CCD (charge coupled device). )
The light source unit case 15 for fixing the lamp 1 is arranged in the copying machine main body 11 so as to move in the left-right direction in the drawing while keeping a constant distance from the document table 12.

In the document reading light source device thus configured, the high frequency power from the oscillation circuit section 8 is transmitted to the coil 3 through the cable 9. As a result, the mercury gas in the bulb 2 is excited by the high frequency electromagnetic field and emits ultraviolet rays. The ultraviolet rays are converted into visible light by the fluorescent body 5 and emitted to the outside through the opening 6.

[Problems to be Solved by the Invention] However, such a document reading light source device has the following problems.

When the electrodeless discharge lamp 1 is turned on, excess mercury in the lamp 1 aggregates near the exhaust pipe 7, which is the coldest part. Then, when the lamp is turned off and then turned on again, the mercury condensed in the exhaust pipe 7 evaporates as the saturated vapor pressure of mercury in the lamp rises as the temperature of the lamp 1 rises. At this time, since the diffusion of mercury in the lamp 1 does not occur instantaneously, the ultraviolet radiation from the discharge space in the vicinity of the exhaust pipe 7 in the lamp 1 is stronger than that in the other discharge spaces, and the light output imbalance phenomenon occurs. Therefore,
The light distribution in the longitudinal direction of the lamp 1 will have an inclination.

Here, if the exhaust pipe 7 is provided near the central portion in the longitudinal direction of the lamp 1, the uneven light distribution in the longitudinal direction is improved,
Instead, in the lamp 1 having the shape in which the straight tube bulbs 2 are arranged in parallel with each other as described above and the discharge spaces communicate with each other near both ends, a difference in light output occurs between the bulbs 2 and 2.

Further, the excess mercury during lighting gathers from the inside of the lamp 1 to the exhaust pipe 7 (coolest part), but in that case, mercury that has been condensed before lighting reaches a portion far from the exhaust pipe 7. ,
It takes a considerable amount of time, and the light output from the lamp 1 and the light distribution fluctuate during that time, which is a serious problem as a document reading light source.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the time from the lighting to the stable light output, and improve the light output and light distribution distribution characteristics in the process of reading an original. In providing a light source device.

[Means for Solving the Problems] The present invention has a valve having at least two straight pipe portions that are parallel to each other, and forms a discharge path that communicates and circulates in the vicinity of both ends of the straight pipe portion, and the periphery thereof. In an original reading light source device including an electrodeless discharge lamp including an induction coil arranged along a discharge path and a circuit section for supplying high-frequency power to the lamp, the original reading light source device faces the two straight tube sections, respectively. As described above, the projection is formed to form the same space as the inside of the valve, and the inner diameter of the communicating portion is made smaller than the inner diameter of the straight pipe portion. In addition, the heating means is provided outside the communication portion.

Hereinafter, the present invention will be described based on examples.

FIG. 1 shows an embodiment of the electrodeless discharge lamp bulb according to the present invention. The difference from the conventional electrodeless discharge lamp is that the two straight pipe portions 2a, 2b constituting the bulb 2 are substantially centered. The exhaust pipes 7a and 7b as protrusions that form the same space as the inside of the valve 2 are provided so as to face each other, and the two straight pipe portions 2a and 2b of the communication portions 2c and 2d that communicate with each other near their ends. The diameter is smaller than the diameter of the straight pipe portions 2a and 2b.

When the electrodeless discharge lamp configured in this way is turned on,
The mercury that has condensed in the exhaust pipes 7a and 7b evaporates as the temperature inside the bulb 2 rises. Here, the temperature inside the valve 2 is higher in the communicating portions 2c and 2d than in the straight pipe portions 2a and 2b because the pipe diameter is smaller. Therefore, the mercury vapor condensed in one exhaust pipe 7a diffuses into the corresponding straight pipe portion 2a, and the mercury vapor condensed in the other exhaust pipe 7b diffuses into the corresponding straight pipe portion 2b and communicates with each other. The internal temperature of parts 2c and 2d is straight pipe part 2
Since the temperature of one exhaust pipe 7a is higher than that of the other exhaust pipe 7b due to some influence, the excess mercury is diffused in the straight pipe portion 2a and the excess mercury is connected to the communicating portions 2c, 2d. It takes a very long time to diffuse through and diffuse into the other exhaust pipe 7b, and it is used as the original reading light source device according to the present invention (such as continuous lighting for several tens of hours to several hundreds of hours or more). In (), it can be said that the mercury that has aggregated in both exhaust pipes 7a and 7b diffuses into the straight pipe portions 2a and 2b, respectively, and the excess mercury also aggregates in both exhaust pipes 7a and 7b. That is, the diffusion and aggregation of mercury vapor in the discharge space of the one straight pipe portion 2a is caused by the corresponding exhaust pipe 7a.
It can be said that the diffusion and aggregation of mercury vapor in the discharge space of the other straight pipe portion 2b depend on the temperature of the corresponding exhaust pipe 7b and are stable in each case.

Therefore, when such a lamp is turned on, the diffusion of mercury
The agglomeration phenomenon occurs in both straight pipe portions 2a and 2b in the same manner,
The light quantity stability and the light distribution characteristics at the initial stage of lighting are greatly improved as compared with the conventional lamp.

Next, FIG. 2 shows a different embodiment of the electrodeless discharge lamp bulb according to the present invention.
The diameters of the communicating portions 2c, 2d are made substantially the same as the diameters of the straight pipe portions 2a, 2b, and heating means 20a, 20b such as a heater are provided outside each of the communicating portions 2c, 2d, thereby providing another configuration. Is the same as that of the above-described embodiment, the same reference numerals are given to the same components and the description thereof is omitted.

In the electrodeless discharge lamp configured as described above, when the lamp is lit, a current is also applied to the heaters 20a and 20b to connect the communication portions 2c and 2d.
By heating the same, the same effect as in the above-mentioned embodiment can be obtained, and by heating even when the lamp is turned off, the mercury in the bulb 2 will be condensed in the exhaust pipes 7a, 7b in a short time, and a further effect. Is obtained.

[Advantages of the Invention] As described above, the present invention has a valve having at least two straight pipe portions that are parallel to each other, and forms a discharge path that circulates so as to communicate with each other near both ends of the straight pipe portion, and the periphery thereof. In an original reading light source device including an electrodeless discharge lamp including an inductive coil arranged along a discharge path and a circuit section for supplying high-frequency power to the lamp, the original reading light source device faces the two straight tube sections, respectively. As described above, by providing a protrusion that forms the same space as the inside of the valve, and by making the inner diameter of the communication part thinner than the inner diameter of the straight pipe part, or instead of making the inner diameter of the communication part thinner, heating the outside of the communication part. By providing the means, it is possible to provide the original reading light source device in which the stability of the light quantity immediately after the lamp is turned on and the light distribution distribution characteristic in the longitudinal direction of the lamp or in the direction orthogonal thereto are greatly improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the lamp bulb according to the present invention, FIG. 2 is a plan view showing a different embodiment of the lamp bulb according to the present invention, and FIG. 3 is a perspective view showing a conventional example. FIG. 4 is a characteristic diagram showing the relationship between the light output and the coldest spot temperature, and FIG. 5 is a schematic configuration diagram showing the light source section of the conventional copying machine. 1 ... Lamp, 2 ... Bulb, 2a, 2b ... Straight pipe part, 2c, 2d
...... Communication part, 3 ... Coil, 7a, 7b ... Protrusion, 20a, 20b ...
… Heating means.

Claims (2)

[Claims] 1. 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, and a valve which is arranged along the circulating discharge path. Electrodeless discharge lamp consisting of an induction coil,
In an original reading light source device provided with a circuit section for supplying high-frequency power to the lamp, a projection that forms the same space as the inside of the bulb is provided so as to face each of the two straight tube sections, and an inner diameter of the communication section is provided. An original reading light source device characterized in that the diameter is made smaller than the inner diameter of the straight tube portion. 2. The document reading light source device according to claim 1, wherein a heating means is provided outside the communicating portion instead of making the inner diameter of the communicating portion smaller than the inner diameter of the straight pipe portion.