JPS628134A - Light source device - Google Patents

Abstract

PURPOSE:To improve the light distribution of a fluorescent tube and to prevent the shielding of light by excess mercury by providing heat radiating members in contact with or proximity to part of the wall of the fluorescent tube. CONSTITUTION:The fluorescent tube 1 is housed into a lamp house 2 and the tube 1 is fixed by a lamp retainer 3 provided at one end of the house 2. Aluminum sheets 4, 5 are disposed as the heat radiating members so as to contact with both ends of the tube 1 except the main exposing region thereof. The sheets 4, 5 are fixed to the aperture of the house 2 by an adhesive agent 6 and a silicon grease 7 is coated to the parts thereof in contact with the tube 1 in order to improve heat conductivity. Aluminum foil 8 is wound as the reflecting member to partly enclose the wall of the tube 1 along the circumferential surface thereof. An insulating film 9 consisting of polyimide, etc., a plate heater 10 and a cover 11 made of a polycarbonate resin, etc. are successively wound thereon. A temp. sensor such as thermistor is attached to the wall of the tube 1.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a light source device used, for example, as a light source for exposing originals in copying machines, reading devices, etc., or as a light source in electrophotographic optical writing printers, and particularly relates to The present invention relates to a light source device that includes a fluorescent tube as a light emitting means and has means for stabilizing the amount of light.

[Prior art]

Conventionally, the above-mentioned light source device has a planar heater wrapped around a part of the wall of the fluorescent tube, and a cooling fan installed near the fluorescent tube. In this method, the heater and cooling fan were turned on and off depending on the temperature detected by a temperature sensor installed in the lamp, respectively, to maintain the fluorescent tube at a temperature with good luminous efficiency. be.

[Problems with conventional technology]

Generally, the amount of light from a fluorescent tube is determined by mercury vapor pressure and tube current. In particular, since mercury vapor pressure depends on temperature, luminous efficiency is determined by temperature. Generally, the luminous efficiency is highest when the tube wall temperature of the fluorescent tube is about 40 ("C), and decreases when the temperature is higher or lower than that.

In addition, since the mercury vapor pressure is determined by the temperature at the lowest point (coldest point) of the tube wall temperature, the temperature at this coldest point is approximately 40 (°C).
) is desirable.

However, in the conventional device described above, the temperature sensor is installed at the location where the average temperature of the fluorescent tube is detected. 'C) When the above is detected, the cooling fan is activated.

In this case, when the temperature of the tube wall is at its highest just before the cooling fan is activated, the amount of light at the center of the fluorescent tube decreases the most. When the fluorescent tube is cooled by a cooling fan, the luminous efficiency of the fluorescent tube as a whole increases, but because the part near the cooling fan is cooled more, the mercury vapor moves temporarily until it stabilizes. .

The amount of light in this part increases further. Furthermore, when the cooling fan stops, the opposite phenomenon occurs, and the amount of light in this area decreases. In this way, with conventional equipment.

As the cooling fan turns on and off, localized temperature changes occur, which changes the location of the coldest spot and its temperature, resulting in fluctuations in the amount of light and worsening the light distribution of the fluorescent tube. The problem arises.

Further, excess mercury within the fluorescent tube is deposited at the coldest point.

In conventional equipment, the location of the coldest spot varies depending on the structure of the mounting machine or the state during cooling. 2 Normally, when heating and cooling are not performed externally, the coldest spot is at both ends or in the center where the temperature is relatively low. It's easy to become.

Therefore, excess mercury tends to precipitate in these parts.

If this excess mercury precipitates on a portion of the aperture in front of the fluorescent tube, it will block light and adversely affect images in copying machines and the like.

[Purpose of the invention]

In view of the above-mentioned drawbacks of the conventional art, the present invention provides good light distribution of the fluorescent tube.
It is also an object of the present invention to provide a light source device that prevents light from being blocked by excess mercury.

[Key points of the invention]

In order to achieve the above object, the present invention is characterized in that, in a light source device equipped with a fluorescent tube, a heat radiating member is provided in contact with or in close proximity to a part of the tube wall of the two fluorescent tubes.

[Embodiments of the invention]

Nine embodiments of the present invention will be described below with reference to one drawing.

FIG. 1 is a perspective view showing an embodiment of the present invention. Here, a fluorescent tube 1 is housed in a lamp house 2 having a U-shaped cross section, and a lamp holder 3 is installed at one end of the lamp house 2.
The fluorescent tube 1 is fixed by. In addition, as a heat dissipation member, aluminum Mi, 4. 5 are arranged so as to contact both ends of the fluorescent tube 1 other than the main exposure area (the central area actually used as a light source). Here, as is clear from the AA sectional view shown in FIG. 2, the aluminum plate 4.5 is fixed to the opening of the lamp house 2 with an adhesive 6.

The contact portion with the fluorescent tube 1 is coated with silicone grease 7 to improve thermal conductivity.

Furthermore, in this embodiment, a reflective member with a thickness of about 50 [μm] is provided along the circumferential surface of the fluorescent tube 1 so as to surround a part of the tube wall.
An aluminum foil 8 is wrapped around the aluminum foil 8, and an insulating film 91 made of polyimide or the like, a heating layer 10 in the form of a sheet, and a cover 11 made of polycarbonate resin or the like are wrapped in order from above. here,
A temperature sensor (not shown) such as a thermistor is attached to the tube wall of the fluorescent tube 1, and a heater 10 and a cooling fan (not shown) are operated based on the tube wall temperature detected by this temperature sensor. .

This embodiment has the above-mentioned structure, and in particular, by providing the aluminum plate 4.5, the heat generated in the fluorescent tube 1 is transferred to the aluminum plate 4.5.
5 and is released to the outside. Therefore, altfl
! 4.5 is always the coldest point of the fluorescent tube l,
It is 10 to 30 degrees lower than other parts. Mole,
Even if the temperature of the tube wall rises due to self-heating or the like during continuous lighting of the fluorescent tube 1, the luminous efficiency of the fluorescent tube 1 will hardly decrease because it is determined by the temperature of the coldest point.

Further, even when the fluorescent tube 1 starts up immediately after lighting or when the cooling fan operates, the position of the coldest point does not change, and the temperature of the coldest point does not change suddenly.

The tube wall temperature changes uniformly throughout. Therefore, even in such a case, there is almost no variation in the amount of light from the fluorescent tube 1.

Prevents deterioration of light distribution. Figure 3 shows that as the tube wall temperature increases,
Changes in light intensity when the cooling fan operates are measured using aluminum plates 4 and 5.
A comparative example is shown between a case (1) in which the device is provided and a conventional case (n) in which the device is not provided. As is clear from the figure, in the case of ■, there is a large fluctuation (variation rate of 10.5%), while in the case of ■, there is almost no fluctuation (variation rate of 1.3%), and the amount of light is stable. Furthermore, in this example, aluminum F14.5
By.

By artificially providing the coldest point outside the main exposure area of the fluorescent tube 1, all excess mercury can be collected at this coldest point. Therefore, effective light is prevented from being blocked by excess mercury.

Furthermore, in this embodiment, an aluminum foil 8 is provided between the fluorescent tube 1 and the heater 10, and this aluminum foil 8 for the reflector is different from the aluminum vapor-deposited film conventionally used in its place. It has a heat distributing effect. That is, due to the thermal conductivity of the aluminum foil 8, the coldest point can be warmed up more quickly, and the temperature difference with the surrounding area can be reduced.

Therefore, even when lighting is started from a low temperature state, there is no drop in the amount of light immediately after warm-up, and the time required for warm-up is shortened. Figure 4 shows that at low temperature (5('
C) The rise characteristics of the light intensity when the lighting starts at '),
A comparative example is shown between a case (I [[)) provided with aluminum foil 8 and a conventional case (IV) provided with an aluminum vapor-deposited film. As is clear from the figure, in the case of ■, there is a large fluctuation (variation rate of 68.5%), whereas in the case of ■, there is little fluctuation (variation rate of 1006%).

In addition, this variation rate was also calculated|required by the formula mentioned above.

Furthermore, an aluminum foil 8 is provided between the fluorescent tube 1 and the heater 10, and this is grounded.

Leakage current flowing through the heater 10 can be prevented.

That is, the fluorescent tube 1 is generally lit at a high frequency.

Further, since the heater 10 operates at ACloo (V), leakage current is likely to occur in the heater 10 due to electromagnetic induction, but this is prevented by shielding with the aluminum foil 8.

In the above embodiment, an aluminum plate was used as the heat dissipation member, but any material with good thermal conductivity such as a copper plate or an iron plate may be used. Further, the shape of the heat radiating member is not limited to a plate shape, but may be, for example, a rod shape. Furthermore,
There is no need for the heat dissipation member to be in direct contact with the fluorescent tube, and it may be provided as close as possible to obtain a sufficient heat dissipation effect.

Further, in the above embodiments, for example, copper foil may be used instead of aluminum foil; that is, any material with good thermal conductivity and light reflectivity may be used.

〔Effect of the invention〕

As explained above, according to the present invention, since the position of the coldest point of the fluorescent tube is artificially determined by the heat dissipation means, the position of the coldest point of the fluorescent tube is This means that the temperature change at the coldest point can be kept to a minimum.This makes it possible to improve the light distribution of the fluorescent tube especially during continuous lighting, and also to keep the temperature of the fluorescent tube constant. By controlling this, it is possible to light the fluorescent tube in a state with the highest luminous efficiency.

Further, by arranging the heat dissipation means so that the position of the coldest point is outside the main exposure area, surplus mercury can be deposited outside the main exposure area, and light blocking due to this precipitation can be prevented.

Therefore, if the light source device according to the present invention is used as a light source for a copying machine, an optical writing printer, etc., extremely high quality and stable images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention. FIG. 2 is a sectional view taken along line A-A of the embodiment shown in FIG. FIG. 3 is a graph showing the variation in light amount when the cooling fan is operated, comparing the above embodiment with the conventional example. FIG. 4 is a graph showing a comparison of the rise characteristics of the light amount at the start of lighting between the above embodiment and the conventional example. 1... Fluorescent tube. 2... Lamp house. 4.5...Aluminum plate. 7... Silicone grease.

Claims (2)

[Claims] (1) A light source device comprising a fluorescent tube, characterized in that a heat radiating member is provided in contact with or in close proximity to a part of the tube wall of the fluorescent tube. (2) The light source device according to claim 1, wherein the heat radiation member is an aluminum plate.