JPH0356614B2 - - 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,
Assuming a type that uses the so-called full exposure method,
The present invention relates to an improvement in an exposure apparatus in which flash illumination means is disposed within a reflective cavity surrounded by a highly reflective surface.

[Conventional technology]

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 FIG. 8, this has a housing 2 in which a cavity 1 in the shape of a substantially rectangular box is defined, and a rectangular opening is provided in the top part 2a of the housing, and a copy document 3 is inserted into the opening. A platen 4 made of glass or the like is mounted on which the housing 2 is placed, and the inner wall of the housing 2 is coated with a white diffuse reflection material to form the inner wall surface of the housing 2 as a highly reflective surface 5. A flash illumination means S is disposed inside the housing, and a lens mounting hole is provided approximately at the center of the housing bottom 2b, and an imaging lens 6 is mounted in the lens mounting hole. and the flash illumination means S
For example, one flash light source 8 is installed on the housing side periphery 2c along one side edge of the platen 4, and direct light is installed above the flash light source 8 and directed toward the platen 4. a shade 9 that blocks light, and a blocker 10 that is installed below the flash light source 8 and blocks light directed substantially directly below from the flash light source 8.
It is made up of.

According to this type, when the flash light source 8 emits light during exposure, the light from the flash light source 8 is transmitted through the shade 9 and the blocker 10.
The light is irradiated into the cavity 1 through the gap, and after being diffusely reflected by the high reflection surface 5, it reaches the platen 4. At this time, due to the light shielding effect of the shade 9, the amount of light based on the direct light from the flash light source 8 is not unevenly distributed to each part of the platen 4, and moreover, the direct light of a dangerous level is not directly transmitted to the operator etc. through the platen 4. Concerns about reaching the eyes of surrounding people and causing discomfort to the eyes of the operator etc. are eliminated. In addition, due to the light blocking effect of Brodka 10,
High reflective surface 5 located almost directly below flash light source 8
Since the reflected light from the platen 4 no longer reaches the platen 4 with a short optical path length, the amount of light based on the reflected light is distributed more to a part of the platen 4 than to other parts, and that part becomes a so-called bright spot. The situation is also avoided. Therefore, the amount of light irradiated from the flash light source 8 is distributed approximately equally to each part of the platen 4, and the distribution of the amount of light on the 4 surfaces of the platen is set to be approximately uniform, so that the entire surface of the copy document 3 on the platen 4 is It is illuminated with approximately uniform illuminance.
The original image of the copy document 3 illuminated in this way is then passed through the imaging lens 6 and a light amount correction filter 11 (see Japanese Patent Laid-Open No. 87747/1983) that corrects the decrease in light amount that occurs when passing through the imaging lens 6. The light is projected onto a predetermined photosensitive surface 12 with substantially uniform illuminance.

[Problem that the invention seeks to solve]

However, in the exposure device of such a conventional copying machine, most of the irradiated light from the flash light source 8 is completely blocked by the shade 9 and the blocker 10, and this light is emitted within the space between the shade 9 and the blocker 10. Therefore, the entire irradiation light from the flash light source 8 cannot be effectively used as illumination light on the platen 4 surface. For this reason, a part of the amount of light irradiated by the flash light source 8 is wasted, which not only deteriorates the illumination efficiency of the four platen surfaces, but also requires the use of the flash light source 8, which consumes more power to account for the loss of the amount of irradiation light. However, the problem arises that the cost of the light source increases accordingly. Further, the shade 9 is usually connected to the flash light source 8.
Since the shade 9 is provided close to the flash light source 8, a large amount of thermal energy from the flash light source 8 is conducted to the shade 9. At this time, since the shade 9 is usually formed in a simple flat plate shape, the shade 9
The heat dissipation area is extremely limited. Therefore, the thermal energy conducted to the shade 9 is not sufficiently released into the cavity 1, and accordingly, the thermal energy is gradually accumulated in the shade 9. As a result,
The temperature of the shade 9 itself becomes abnormally high, causing premature deterioration of the shade 9 due to the heat, resulting in a lack of protection for the flash illumination means S.

Furthermore, in the exposure device of a conventional copying machine, the illuminance of the photosensitive surface area corresponding to the shade is somewhat insufficient compared to other parts, which has a considerable adverse effect on the quality of the copied image.

This invention was made to solve the above problems, and it improves the illumination efficiency of the platen surface while ensuring the safety of the eyes of the operator and other people around him and reducing the cost of the light source. The present invention provides an exposure device for a copying machine which can effectively protect flash illumination means from heat and further improve the uniformity of illuminance distribution on a photosensitive surface.

[Means for Solving the Problems] That is, the present invention provides a housing having a substantially box-shaped cavity surrounded by a highly reflective surface and having an opening at the top, and a housing that is attached to the opening of the housing to place a copy original. A platen comprising a surface and formed of a transparent member, a flash illumination means disposed within the housing, and an imaging lens mounted in a hole formed approximately in the center of the bottom of the housing, A copying apparatus in which the entire surface of the copy document on the platen is substantially uniformly illuminated by illumination light from a flash illumination means, and the original image of the copy document is projected onto a predetermined photosensitive surface via the imaging lens. Assuming that the flash illumination means is an exposure device of a machine, the flash illumination means includes a flash light source installed in the housing, and is installed to cover at least an upper part of the flash light source and to correspond to the direct light path from the flash light source to the platen. The present invention is characterized in that the shade is formed into a blind shape by a group of reflective plates made of a semi-transparent member with low transmittance.

[Operation] According to the above-mentioned technical means, most of the light from the flash light source is blocked by the reflection plate group of the shade and guided to the platen after multiple reflections within the cavity, while a portion of the light from the flash light source is The light passes directly through the shaded portion and reaches the platen area above the shaded portion.

Thermal energy from the flash light source is conducted to the shade, and each reflection plate of the shade functions as a heat radiating member.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

In the embodiment shown in FIGS. 1 to 3, the basic configuration of the exposure device of the copying machine is almost the same as the conventional one.
A housing 2 in which a substantially box-shaped cavity 1 is surrounded by a highly reflective surface 5, a platen 4 attached to an opening in the top portion 2a of the housing, a flash illumination means S disposed within the housing 2, and a bottom portion 2b of the housing. and an imaging lens 6 that is attached to the lens attachment hole of the image forming apparatus.

In this embodiment, the flash illumination means S, unlike the conventional one, includes four flash light sources 20 (specifically, 20a to 20d) installed on the housing bottom 2b along each side edge of the platen 4;
It includes a shade 25 (specifically, 25 to 25d) that covers the upper and front side of each flash light source 20. As shown in FIG. 2 in particular, each shade 25 has a large number of flat plates 26 arranged at predetermined intervals in a substantially horizontal position, and the flat plates 26 are connected to each other via a connecting member 27. The flat plates 26 act as if they constitute a brine, and are attached to the housing bottom 2b and the housing side circumference 2c via brackets not shown. in this case,
Shade 2 covering above the flash light source 20
5 parts are each flat plate 2 in the horizontal plane direction.
6 are partially overlapped with each other, and are designed to block light directed upward from the flash light source 20. On the other hand, the shade 25 portion that covers the front side of the flash light source 20 is attached to each flat plate 2.
6 is arranged in a phase-polymerized manner.
Furthermore, each of the flat plates 26 is made of a semi-transparent member with low transmittance, and is adapted to reflect light with relatively high reflectance.

It should be noted that the same constituent members as in the prior art are designated by the same reference numerals as in the prior art, and detailed explanation thereof will be omitted here.

Therefore, according to the exposure device for a copying machine according to this embodiment, when each flash light source 20 emits light during exposure, most of the light from each flash light source 20 is directly or directly emitted, as shown in FIG. After being once blocked by the shade 25, the light is irradiated into the cavity 1 through each opening 28 of the shade 25.
At this time, most of the direct light from the flash light source 20 toward the platen 4 is blocked by the shade 25 that covers the upper part of the flash light source 20, as shown by arrow A. The light is not distributed non-uniformly to each part of the four sides, and there is no concern that the direct light will harm the eyes of the operator or other people around him. Further, among the reflected light from the high reflection surface 5 located almost directly below the flash light source 8, the light having a particularly short optical path length to reach the platen 4, as shown by arrow B,
Since it is mainly blocked by the shade 25 that covers the front side of the flash light source 20, the amount of light based on the reflected light is not distributed more to a part of the platen 4 than to other parts, and a part of the platen 4 is There is no concern that it will become a particularly bright bright spot. The light blocked by the shade 25 is transmitted to the flat plate 25 as shown by arrows A and B.
It is guided into the cavity 1 through the opening 28 of the shade 25 while being reflected between them. In this state, since the light irradiated into the cavity 1 is mainly directed toward the wall surface of the housing 2, the irradiated light reaches the platen 4 after being diffusely reflected by the high reflection surface 5 and the reflective surface of the shade 25. do. Therefore, the amount of light reaching each part of the platen 4 is distributed approximately equally, and the entire surface of the copy original 3 on the platen 4 is illuminated with approximately uniform illuminance. Then, the copy original 3 illuminated in this way
The original image is projected onto a predetermined photosensitive surface 12 with substantially uniform illuminance via an imaging lens 6 and a light amount correction filter 11, as in the conventional case.

In addition, in such an exposure process, the light blocked by the shade 25 is irradiated into the cavity 1 without being trapped within the shade 25.
The irradiated light from the flash light source 20 is used as illumination light for the platen 4 without any waste.

Furthermore, since the shade 25 is blind-shaped with a large number of flat plates 26, the surface area of the shade 25 is sufficiently larger than that of a simple flat plate shade. Therefore, even if the heat energy from the flash light source 20 is conducted to the shade 25, the heat energy conducted to the shade 25 is efficiently released into the cavity 1 because the heat radiation area of the shade 25 is large. Therefore, thermal energy is not accumulated in the shade 25 unnecessarily, and the situation where the temperature of the shade 25 becomes abnormally high and the shade 25 itself deteriorates due to heat is effectively prevented. Avoided.

Furthermore, in this embodiment, the shade 25 portion that covers the front side of the flash light source 20 is
As shown by arrow C in the figure, direct light directed diagonally downward from the flash light source 20 to the imaging lens 6 is also blocked, so that the direct light from the flash light source 20 passes through the imaging lens 6. The light does not reach the photosensitive surface 12, and the situation in which the projected image on the photosensitive surface 12 is damaged by the direct light is effectively avoided. Furthermore, the shade 25 portion that covers the front side of the flash light source 20 functions similarly to the conventional blocker 10, and the conventional blocker 10 is therefore unnecessary, reducing the number of parts constituting the flash illumination means S. Reduce.

Further, according to this embodiment, when the flash light source 20 emits light during exposure to substantially uniformly illuminate the 4 surfaces of the platen, the original image light of the copy document 3 on the platen 4 is mainly exposed on the photosensitive surface 12. In addition to reaching
A small amount of reflected light from the platen 3 reaches the platen. At this time, the distribution of the amount of reflected light on the photosensitive surface 12 matches the illuminance distribution inside the corresponding housing 2, but in the case of the comparative example type in which the shade 25 is formed of a non-transparent material, the shade 25 portion Since the reflected light from the cavity is once diffusely reflected within the cavity 1, as shown by D in Fig. 3,
The intensity level of the reflected light becomes weaker than the level of the reflected light from the highly reflective surface 5 of the housing 2. Therefore, the distribution of the amount of reflected light on the photosensitive surface 12 is lower at a portion of the photosensitive surface 12 corresponding to the shade 25 than at other portions, as shown by the imaginary line in FIG. The reflected light amount distribution becomes non-uniform. Therefore, even if the original image light amount distribution on the photosensitive surface 12 is kept approximately uniform as shown in FIG.
The light amount distribution of the above projected image becomes non-uniform due to the influence of the uneven reflected light amount distribution,
The copy image based on the projected image is damaged accordingly.
On the other hand, for the type of this embodiment,
Direct light from the flash light source 20 toward the platen 4 passes through the shade 25 with the intensity level attenuated as shown by symbol E in FIG. The illuminance distribution in the shade 25 portion and the high reflective surface 5 portion of the housing 2 becomes approximately uniform. Therefore, the distribution of the amount of reflected light on the photosensitive surface 12 is set to be approximately uniform as shown by the solid line in FIG. If it is sagging, the light amount distribution of the projected image on the photosensitive surface 12 will be set to be substantially uniform as shown in FIG. 5c. Therefore, the photosensitive surface 12
The illuminance distribution of the upper projection image becomes more uniform than in the comparative example, and the copy image based on the projection image is maintained better accordingly.

Next, a second embodiment shown in FIG. 6 will be described.

The flash illumination means S in this embodiment is
Similar to the above embodiment, a flash light source 20 and a shade 25 are provided, but unlike the first embodiment, a reflector 40 is provided below the flash light source 20.
are installed so that the light directed substantially directly below from the flash light sources 20 is reflected toward the high reflective surface 5 of the housing side peripheral portion 2c facing each flash light source 20.

Therefore, according to this embodiment, since the light directed substantially directly downward from each flash light source 20 is guided into the cavity 1 without being once blocked by the shade 25, the loss of the amount of irradiation light from the flash light sources 20 is reduced as described above. Compared to the example, it is suppressed to a lower level,
Accordingly, the illumination efficiency of the flash illumination means S is further improved.

The specific structure of the shade 25 is not limited to that shown in each of the above embodiments, and the design may be modified as appropriate, such as by holding the flat plate 26 that constitutes the blind shade 25 with a frame. No problem. Furthermore, in each of the above embodiments, the shade 25 is configured to cover the upper and front side of the flash light source 20;
The invention is not necessarily limited to this, but for example, as shown in FIG. 7, only the upper part of the flash light source 20 may be covered with a blind-like shade 35, and the front side of the flash light source 20 may be covered with a conventional blocker 10 or the like. The design may be changed as appropriate. Further, in each of the above embodiments, four flash light sources 20 and four shades are provided in the housing 2, but the present invention is not necessarily limited to this.
An arbitrary number of flash light sources 20 may be installed at desired locations, and shades may be provided correspondingly. Furthermore, it goes without saying that the design of other members constituting the exposure apparatus can be changed as appropriate.

〔Effect of the invention〕

As explained above, according to the exposure device for a copying machine according to the present invention, it is possible to effectively block the direct light directed from the flash light source toward the platen, so that the direct light can be used to protect the operator and other surrounding people. In addition to effectively eliminating the problem of harm to the eyes, the direct light from the flash light source toward the platen is first guided into the cavity and then used as illumination light for the platen, so the amount of light irradiated from the flash light source is wasted. This makes it possible to improve the illumination efficiency of the platen surface, and also to reduce the power consumption of the flash light source by eliminating the loss of the amount of irradiation from the flash light source. It is possible to reduce the cost of the light source. Further, according to the present invention, a large heat dissipation area is ensured for the shade covering the flash light source, so even if heat energy from the flash light source is conducted to the shade, the heat energy is not accumulated in the shade. Therefore, the temperature rise of the shade can be effectively suppressed. Therefore, a situation in which the shade deteriorates prematurely due to heat is avoided, and the flash illumination means can be effectively protected against heat.

In addition, since a part of the direct light from the flash light source toward the platen is attenuated and transmitted through the shade, the lack of reflected light in the platen area above the shade can be effectively resolved, and the This makes it possible to uniformize the distribution of the amount of reflected light on the photosensitive surface, thereby ensuring uniformity of the illuminance distribution of the projected image on the photosensitive surface, and maintaining good copy image quality.

[Brief explanation of drawings]

FIG. 1 is a perspective explanatory view showing a first embodiment of an exposure device for a copying machine according to the present invention, FIG. 2 is a view taken from the direction of the arrow in FIG. 1, and FIG. 3 corresponds to the - line in FIG. 1. FIG. 4 is an explanatory diagram showing the transmitted light path of the shade according to the embodiment, and FIG. 5 a, b
and c is an explanatory diagram showing the distribution of each light amount P of the original image light of the copy document, the reflected light from the platen, and the projected image light generated on the photosensitive surface along the line X-X in FIG.
FIG. 6 is a cross-sectional explanatory diagram of a main part showing a second embodiment of the exposure device for a copying machine according to the present invention, FIG. FIG. 8 is an explanatory cross-sectional view showing an example of a conventional exposure device for a copying machine. Explanation of symbols, S...Flash lighting means, 1...
Cavity, 2... Housing, 3... Copy original, 4... Platen, 5... Highly reflective surface, 6... Imaging lens, 12... Photosensitive surface, 20 (20a to 2
0d)... Flash light source, 25 (25a to 2
5d)... Shade, 28... Opening, 35...
Syed.

Claims (1)

[Claims] 1. A housing that surrounds a substantially box-shaped cavity with a highly reflective surface and has an opening at the top, and a platen that is attached to the opening of the housing and forms a placement surface for a copy original and is made of a transparent member. , comprising: a flash illumination means disposed within the housing; and an imaging lens mounted in a hole formed at the bottom center of the housing; the illumination light from the flash illumination means illuminates the surface of the platen. In an exposure device for a copying machine, which illuminates the entire surface of a copy document substantially uniformly and projects an original image of the copy document onto a predetermined photosensitive surface via the imaging lens, the flash illumination means is located inside the housing. a flashing light source installed in the flashing light source, and a shade installed to cover at least above the flashing light source and corresponding to the direct light path from the flashing light source to the platen, the shade being a semi-transparent member with low transmittance. 1. An exposure device for a copying machine, characterized in that it is formed into a blind shape by a group of reflective plates consisting of.