JPH059720Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a document illumination device for a document reading device or a copying machine.

[Technical background]

3 and 4 show conventional examples of document illumination devices such as document reading devices and copying devices that use fluorescent lamps as light sources.

In other words, 1 is a fluorescent lamp that is a light source, 2 is an arc-shaped sheet heater that controls the temperature of the fluorescent lamp, and 3 is a fluorescent lamp that is a light source.
5 is a socket for holding a fluorescent lamp 1, and 5 is an original glass on which an original 8 to be read or copied is placed and supported. The document illumination device moves relative to the document 8 to scan the document. 6 is a heat generating layer of the planar heater 2, and 7 is an insulating layer.

Note that there is a space between the document glass and the illumination device, but this is necessary in the design to take into account the deflection of the document glass and the change in height due to the movement of the document table. It is installed closest to the base glass.

The amount of light from a fluorescent lamp depends on the temperature of its tube wall, and it is generally said that it emits light most efficiently at around 40°C. Therefore, when a fluorescent lamp is cold, even if the fluorescent lamp is powered and emits light, sufficient light cannot be obtained immediately, and it takes several seconds to several tens of seconds for the tube wall temperature to rise.

Therefore, a planar heater is installed so that when the tube wall temperature of the fluorescent lamp is set to around 40 degrees Celsius in advance and power is applied to the fluorescent lamp, the amount of light rises instantaneously and a predetermined amount of light is obtained. This heater has an arcuate shape for efficient heating, and is tightly attached to the fluorescent light so as to wrap around it using its own elasticity.

In order to efficiently illuminate a document, it is more effective to minimize the distance l between the document reading position A and the tube wall of the fluorescent lamp than to use a reflector or a light guiding member. Generally, the thickness of the heating layer 6 of the planar heater 2 is 0.3 to 0.5 mm, and the thickness of the insulating layer 7 is 0.5 to 0.8 mm.
From the viewpoint of heat generation performance and safety, the wall thickness of the planar heater should be about 1.5 to 2 mm. In addition, the planar heater is attached so that it hugs the fluorescent lamp with its own elasticity, and in order to obtain sufficient clinging force, and to increase the area of the heating layer to obtain heating performance and heat retention performance, the opening angle θ is generally 100
~150℃.

Therefore, when the planar heater 2 is installed in the design of a lighting device, the distance l has to be made longer by the wall thickness of the planar heater 2 compared to when no planar heater is installed. .

As a result, the amount of light at the document reading position A is reduced and the fluorescent lamp cannot be used efficiently, resulting in shorter replacement intervals.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an original illuminating device that can efficiently illuminate an original.

[Configuration overview]

In order to achieve the above object, the present invention provides an original illumination device having an arc-shaped planar heater in close contact with a fluorescent lamp, in which the tip of the planar heater near the document support member in the circumferential direction faces the document support member. The tip is tapered.

〔Example〕

Fig. 1 is a sectional view of the embodiment of the present invention, and Fig. 2 is a cross-sectional view of the embodiment of the present invention.
3 is a cross-sectional view of the planar heater portion in the figure
Components having the same functions as those in FIG. 4 are given the same reference numerals, and explanations are omitted unless particularly necessary.

As shown in FIGS. 1 and 2, the end (circumferential end) of the opening of the arcuate sheet heater 2 is provided to a position facing the document table glass and the adjacent fluorescent light. By making the insulating layer at this end tapered and thin, it becomes tapered and has a distance l compared to a planar heater with the same wall thickness.
It is possible to make it shorter. As an example, if we use a planar heater 2 with a uniform wall thickness of 1.5 mm and a lighting device with a distance l of 11 mm, the aperture angle is the same,
By using the planar heater 2 shaped according to the present invention, it is possible to shorten the distance l by about 1 mm, and as a result, the amount of light at the document reading position A can be reduced by about 10%.
can be increased. Further, since the aperture angle θ can be made the same as that shown in FIG. 4, the clinging power to the fluorescent lamp and the heat retaining power are not reduced.

In Figures 1 and 2, both circumferential ends of the sheet heater 2
1 and 22 are tapered so that only the end 21 near the original glass 5 is tapered,
The end portion 22 may have a shape as shown in FIG.

However, by tapering the end portion 22 as well, it becomes possible to bring the two lamps 1 closer to each other, which contributes to improving the illuminance at point A.

〔effect〕

As explained above, the document illumination device according to the present invention tapers the thickness of the opening of the sheet heater to bring the fluorescent lamp closer to the document, thereby increasing the amount of light at the document reading position and efficiently using the fluorescent lamp. can be used.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the embodiment of the present invention, and Fig. 2 is a cross-sectional view of the embodiment of the present invention.
3 is a sectional view of the planar heater in the embodiment, FIG. 3 is a sectional view of the conventional example, and FIG. 4 is a sectional view of the planar heater of the conventional example. 1 is a fluorescent lamp, 2 is a sheet heater, and 5 is a document glass.

Claims (1)

[Scope of utility model registration request] In a document illumination device that has an arc-shaped planar heater that is in close contact with a fluorescent lamp, the tip of the planar heater that is closer to the document support member in the circumferential direction is provided to a position facing the document support member; A document illumination device characterized by being tapered.