JPH0449696B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an exposure device for a copying machine, and in particular,
This invention relates to an improvement in an exposure apparatus that employs a so-called full-surface exposure method using a single flash light source.

[Prior art]

A conventional exposure device for this type of copying machine is disclosed in, for example, Japanese Patent Laid-Open No. 115058/1983.
As shown in FIGS. 1 and 2, this has a housing 2 that defines a substantially box-shaped cavity 1, and the inner wall of this housing 2 is coated with a white diffuse reflection material. The inner wall surface of the housing 2 is formed as a high slope 3, while an opening is formed in the top part 2a of the housing 2, and a platen glass 4 on which a copying object 10 such as a manuscript is placed is inserted into the opening. A flash light source 5, such as a flash xenon lamp, is installed on one side of the inner wall surface of the side peripheral portion 2b of the housing 2 via a bracket 6, and a flash light source 5, such as a flash xenon lamp, is installed on one side of the inner wall surface of the side peripheral portion 2b of the housing 2, and a flash light source 5, such as a flash xenon lamp, is installed via a bracket 6. A lens mounting hole is provided, and an imaging lens 7 is inserted into the lens mounting hole via a lens case 8.

In such a type, if the direct light from the flash light source 5 is directed directly to the platen glass 4, not only will the light intensity distribution on each part of the platen glass 4 surface be likely to become uneven, but it will also cause trouble to the operator's eyes. Usually, the flash light source 5 is placed above the flash light source 5.
A lamp shade 11 is installed to cover the platen glass 4 and block direct light from the flash light source 5 toward the platen glass 4. In addition, the light from the flash light source 5 is subjected to multiple reflections within the cavity 1 and then heads toward the platen glass 4.
Since the flash light source 5 is disposed biased toward one side of the side circumferential portion 2b of the housing 2, as shown by the imaginary line in FIG. After being reflected, the light immediately reaches a portion of the platen glass 4 that is close to the flash light source 5. in this case,
Since the above-mentioned optical path length is shorter than the others, the amount of light in the portion of the platen glass 4 close to the flash light source 5 inevitably increases, and accordingly,
This area becomes a bright spot with higher illuminance than other areas, causing a loss in copy image quality. In order to avoid the occurrence of such bright spots, a blocker 12 is conventionally installed below the flash light source 5. This blocker 12 is, for example, shown in FIGS. 1 to 3.
As shown in the figure, there is a bottom plate part 13 made of metal such as aluminum and arranged horizontally facing the flash light source 5, and a bottom plate part 13 that is erected on the periphery of the bottom plate part 13 except for the edge near the housing 2. A side plate portion 14 surrounding the flash light source 5 is provided between the side plate portion 14 and the wall surface of the housing 2 . In this case, the light directed substantially directly downward from the flash light source 5 will be blocked by the bottom plate portion 13 of the blocker 12, and even if the light reflected by the bottom plate portion 13 attempts to head toward the platen glass 4, the platen glass 4 will be blocked by the platen glass 4. Since the light directed toward the glass 4 is effectively blocked by the side plate portion 14, the situation in which bright spots are formed on the surface of the platen glass 4 can be effectively avoided. In addition, in Figures 1 and 3,
Reference numeral 15 designates a notch provided in a part of the side plate portion 14 of the blocker 12 for light passage.

Therefore, according to such a conventional exposure device for a copying machine, when the flash light source 5 emits light during exposure, the light from the flash light source 5 is transmitted through the gap 18 between the lampshade 11 and the blocker 12 into the cavity 1. The light is irradiated into the cavity 1 and reaches the platen glass 4 after multiple reflections within the cavity 1. At this time, due to the action of the lamp shade 11 and the blocker 12, the light intensity distribution on the four surfaces of the platen glass becomes approximately uniform.
Copying object 1 on platen glass 4 with approximately uniform illuminance
0 entire surface is illuminated at the same time. As a result, the illuminated original image of the entire copying machine 10 is transmitted to the predetermined photosensitive surface 9 through the imaging lens 7 with substantially uniform illuminance.
Therefore, the copy image quality based on the projected image is secured to a certain extent.

However, in such a conventional exposure device for a copying machine, the blocker 12 is installed so as to surround the flash light source 5, so that the light directed substantially directly below from the flash light source 5 is transmitted through the lampshade 11 and the blocker. 12, and does not work as illumination light on the four sides of the platen glass. For this reason, the flash light source 5
Not only is a part of the amount of illumination light emitted from the device was wasted, but the flash light source 5, which consumes a large amount of power, must be used to compensate for the loss of the amount of illumination light, resulting in an increase in cost. .

In addition, in the case of a type in which only one flash light source 5 is installed, such as the exposure device of a conventional copying machine, there is a technical problem that the illuminance of the area of the platen glass 4 on the side far from the flash light source 5 is insufficient. Challenges still remain.

As a conventional means for solving this technical problem, for example, by applying the technology disclosed in Japanese Patent Application Laid-open No. 55-29899, a reflector is disposed in the lower part of the flash light source 5.
The light directed substantially directly downward from the flash light source 5 is directed to the inner wall surface (corresponding to a reflective member) of the housing 2 on the side facing the flash light source 5, and the illuminance of the area of the platen glass 4 on the side away from the flash light source 5 is supplemented. Conceivable.

However, in this type, the reflection direction of the reflector is limited to the direction (one direction) of the inner wall surface of the housing 2 facing the flash light source 5, so if the flash light source 5 with a small axial dimension is used, the flash light source 5 It is not possible to solve the problem of insufficient illuminance on the side portion of the platen glass 4 located on the side of the light source 5. For this reason, conventionally, a flash light source 5 with an axial dimension that is approximately equal to the dimension of one side edge of the platen glass 4 has been used.
With the increase in size, the housing 2 has to be increased in size, resulting in the technical problem of increasing the size of the device itself.

This invention was made to solve the above technical problem, and it is possible to effectively utilize the amount of light emitted from the flash light source without wasting it without making the flash light source unnecessarily large. The present invention provides an exposure device for a copying machine that further improves the uniformity of illuminance distribution on a surface.

[Means for Solving the Problems] That is, the present invention includes a housing that defines a substantially box-shaped cavity and has an inner wall surface formed as a high slope, and a housing that is attached to an opening formed at the top of the housing. a platen that constitutes a surface on which a copy is placed and is made of a transparent material; a flash light source installed on one side of an inner wall surface of a side peripheral portion of the housing; and direct light directed from the flash light source toward the platen. a lampshade installed above the flash light source so as to block the flash light source, and an imaging lens installed in a hole formed approximately in the center of the bottom of the housing, and multiplexes the light from the flash light source within the cavity. The exposure device of a copying machine is assumed to be such that the entire surface of the object to be copied on the platen is simultaneously illuminated by reflection, and the certified original image of the object to be copied is projected onto a predetermined photosensitive surface via the imaging lens. A reflector was installed below the flash light source to diffusely reflect the light directed substantially directly below from the flash light source toward the inner wall surface of the housing facing the flash light source and the inner wall surface of the housing located on the side of the flash light source. It is characterized by this.

[Function] According to the above-mentioned technical means, the light directed almost directly below from the flash light source is directed to the inner wall surface of the housing facing the flash light source and the inner wall surface of the housing located on the side of the flash light source via the reflector. Once there was a diffuse reflection.

Therefore, the situation in which the light directed almost directly below the flash light source is immediately reflected within the housing and goes toward the platen side is eliminated, and the light from the reflector is guided to the inner wall surface of the housing on the side away from the flash light source. The amount of light irradiated from this part increases compared to the type without a reflector.

[Example] Hereinafter, the present invention will be described in detail based on an example shown in the accompanying drawings.

In the embodiment shown in FIGS. 4 and 5, the exposure apparatus includes a housing 2, a platen glass 4, a flash light source 5, a lampshade 11, and
and an imaging lens 7, but unlike the conventional one, a reflector 20 is provided below the flash light source 5.

The reflector 20 is configured as a plate-like member made of glossy aluminum or any metal with aluminum vapor-deposited on its surface, and whose length is approximately equal to the length of the flash light source 5. The reflector 20 has a reverse slope 21 on a curved surface facing the flash light source 5, and is further provided with a bead 27 having a mountain-shaped cross section in the center thereof.
7 is formed as another opposite slope 21d whose reflection direction is substantially orthogonal to the reflection direction of the opposite slope 21, and the opposite slope 21 directs light from the flash light source 5 toward the housing 2.
The side periphery 2b of the housing 2 is diffusely reflected toward the part A facing the flash light source 5, and the reverse slope 21d allows the light directed substantially directly below from the flash light source 5 to be reflected from the side periphery 2b of the housing 2. The light is diffused and reflected toward a portion located on the side of the flash light source 5.

In addition, in FIGS. 4 and 5, reference numeral 22 is a mounting piece for the reflector 20, and reference numeral 23 is a stopper for mounting the reflector 20.

Further, in this embodiment, a filter 25 is provided on the photosensitive surface 9 side of the imaging lens 7, and has a transmittance obtained as the reciprocal of cos ⁴ θ depending on the angle of incidence (θ) on the imaging lens 7. The filter 25
is attached to the lens case 8, for example.

Therefore, according to the exposure apparatus of the copying machine according to this embodiment, when the flash light source 5 emits light, the light from the flash light source 5 is transmitted through the gap 26 between the lampshade 11 and the reflector 20, as shown by arrow a. The light is directly irradiated into the cavity 1, and after multiple reflections within the cavity 1, it reaches the platen glass 4.

Furthermore, as shown by arrows b and c in FIG. 4 and FIG.
21d, the light is diffusely reflected and irradiated into the cavity 1, and after being diffusely reflected on the inner wall surface A of the housing 2, it undergoes multiple reflections within the cavity 1, and finally reaches the platen glass 4.

At this time, since the light traveling substantially directly below from the flash light source 5 has a short optical path length and does not reach the part of the platen glass 4 that is close to the flash light source 5, the part of the platen glass 4 that is close to the flash light source 5 is bright. Not only can the situation where the light become a spot be avoided, but also the flash light source 5 can be
There is no situation where the light that goes almost directly below from the flash light source 5 gets stuck in the space between the reflector 20 and the lampshade 11, and the light that goes almost directly below the flash light source 5 is directed to the side far away from the flash light source 5 where the amount of light is insufficient. The amount of light on the inner wall surface A of the housing 2, specifically, on the inner wall surface of the housing 2 facing the flash light source 5 and on the inner wall surface portion of the housing 2 located on the side of the flash light source 5, is increased.

Therefore, the light from the flash light source 5 is uniformly irradiated onto each part of the inner wall surface of the housing 2, and after multiple reflections within the cavity 1, the amount of irradiated light on each part of the 4 surfaces of the platen glass becomes more uniform than before. , the entire surface of the object 10 on the platen glass 4 is simultaneously illuminated with more uniform illuminance.

In addition, in this embodiment, the above-mentioned copy object 1
0 The entire original image has uniform illuminance through the imaging lens 7.
Even if it is projected through the imaging lens 7, the amount of projected light will decrease by cos ⁴ θ depending on the angle of incidence (θ), due to the characteristics of the imaging lens 7.
The reduced light amount is corrected to the original light amount again by the filter 25, so that the projected image of the entire object 10 to be copied is maintained at a uniform illuminance after passing through the filter 25, and is projected onto the photosensitive surface 9. be done. Therefore, there is no concern that the quality of the copy image based on the projected image on the photosensitive surface 9 will be impaired.

Regarding the specific configuration of the reflector 20,
The reflector 20 is not limited to the one shown in the above embodiment, and for example, the reflector 20 may be formed in a multi-stage sawtooth wave shape, and reflective surfaces 21, 21d as shown in the embodiment may be formed at each step. Of course, the design of other parts constituting the exposure apparatus can be changed as appropriate.

[Effects of the Invention] As described above, according to the exposure device for a copying machine according to the present invention, the light from the flash light source is irradiated into the cavity directly or through a reflector without waste, so that the light from the flash light source is not wasted. In addition to being able to use the amount of light emitted from the flash light source effectively as illumination light on the platen surface, there is no loss in the amount of light emitted by the flash light source, so the power consumption of the flash light source does not increase unnecessarily. Accordingly, the cost of the flash light source can be reduced accordingly.

Further, according to the exposure device for a copying machine according to the present invention, the light that causes bright spots is actively distributed to the cavity region on the side away from the flash light source where the light amount is insufficient. The distribution of the amount of light within the platen can be made uniform, and the distribution of illuminance on the platen surface can be made more uniform.

Furthermore, according to the exposure device for a copying machine according to the present invention, the direction of reflection of light from the reflector is outside the inner wall surface of the housing facing the flash light source.
Since the inner wall surface of the housing located on the side of the flash light source is also targeted, even if the flash light source has a small axial dimension in conjunction with the box-shaped housing, the inner wall surface of the housing on the side away from the flash light source 5 will be covered. It is possible to reliably supply light to the platen surface and to make the illuminance distribution uniform on the platen surface, thereby effectively preventing the flash light source from increasing in size.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of an exposure device of a conventional copying machine, and FIG.
3 is an enlarged perspective view showing a specific example of a Brodska; FIG. 4 is a sectional view similar to FIG. 2 showing an embodiment of an exposure device for a copying machine according to the present invention;
The figure is a perspective view of the main part. Description of symbols, 1...Cavity, 2...Housing, 2a...Top, 2b...Side periphery, 2c...Bottom, 3...High reflective surface, 4...Platen glass (platen), 5...Flash Light source, 7... Imaging lens, 9... Photosensitive surface, 10... Subject to be copied, 11...
...Lampshade, 20...Reflector.

Claims (1)

[Claims] 1. A housing defining a substantially box-shaped cavity and having an inner wall surface formed with a high slope, and a transparent material that is attached to an opening provided at the top of the housing to constitute a surface on which a copy is placed. a platen formed of a metal platen, a flash light source installed on one side of the inner wall surface of a side peripheral portion of the housing, and a flash light source installed above the flash light source so as to block direct light directed from the flash light source toward the platen. The lampshade includes a lampshade and an imaging lens attached to a hole formed in the bottom center of the housing, and the light from the flash light source is reflected multiple times within the cavity to simultaneously illuminate the entire surface of the object to be copied on the platen. In the exposure device of the copying machine, which projects the illuminated original image of the object to be copied onto a predetermined photosensitive surface through the imaging lens, there is a device located below the flash light source, which is located approximately directly below the flash light source. 1. An exposure device for a copying machine, characterized in that a reflector is installed to diffusely reflect light directed toward an inner wall surface of a housing facing a flash light source and an inner wall surface of a housing located on the side of the flash light source.