JPH0481174B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a slit exposure device used in copying machines, facsimile machines, etc. The present invention relates to an improvement of a slit exposure device.

[Conventional technology]

To explain a conventional slit exposure apparatus using an original moving type as an example, this type of slit exposure apparatus has a transparent platen 1 movably provided as shown in FIG. An irradiation means S is fixedly disposed in the irradiation means S.
The original 2 placed on the platen 1 is illuminated in a slit shape from one end to the other, and a slit-shaped partial image of the original 2 is projected onto a predetermined photosensitive surface 4 via an imaging lens 3. The images are sequentially projected onto the screen.

In such a type, the lighting means S
For example, as shown in FIG. 3, this comprises a fluorescent lamp 5 in which a fluorescent paint 5a is applied to the inner wall of the tube through a reflective film (not shown), and a light condensing part M on the two sides of the original is provided with a fluorescent lamp 5. An opening 6 for light irradiation is provided by peeling off the reflective film and the fluorescent paint 5a in the form of a slit at opposing inner wall portions of the tube. In this case, since the irradiated light from the fluorescent lamp 5 is irradiated to the outside through the opening 6, the irradiated light is mainly directed toward the condensing part M on the surface of the document 2 facing the opening 6. The illuminance at the light condensing section M is set to a predetermined level. In FIG. 3, reference numeral 7 denotes a lamp heater that surrounds the fluorescent lamp 5 and heats the fluorescent lamp 5.

[Problem that the invention seeks to solve]

However, in such a conventional slit exposure apparatus, the fluorescent lamp 5 has a characteristic that the irradiated light from the opening 6 is diffused. light is manuscript 2
Not only is the light not efficiently focused on the light condensing part M on the surface, it becomes difficult to set the width of the light condensing part M narrowly. Therefore, in order to set the illuminance at the light condensing part M to be appropriate, it is necessary to use a fluorescent lamp 5 with a sufficiently large amount of irradiated light, and the power consumption of the fluorescent lamp 5 is accordingly reduced. This results in a situation where the amount of work increases.

As a means to prevent such a situation, conventionally, as shown by the imaginary line in FIG. A system has already been proposed in which the irradiated light from 6 is reflected directly or by the light condensing reflector 8 to be focused on a light converging portion M on the two sides of the document. According to this type,
Due to the light condensing effect of the condensing reflector 8, the illumination efficiency for the condensing part M on the second side of the original is improved to some extent. In addition to the luminous flux that goes directly to the condenser reflector 8, it is necessary to secure a certain amount of luminous flux that goes to the condensing reflector 8. Therefore, it is necessary to set the aperture angle θ of the aperture 6 of the fluorescent lamp 5 to a certain degree (approximately 60 to 75 degrees). degree). In this case, since the aperture angle θ becomes relatively large, the width of the condensing part M on the second side of the document is not sufficiently narrow, and as shown in FIG. The luminance at 6 is also lower than when the aperture angle θ is small, and accordingly, the illumination efficiency in the light condensing section M cannot be obtained as sufficiently high.

Therefore, as another conventional means for preventing such a situation, as shown in FIG.
The aperture angle θ at the aperture 6 is set to a narrow value of about 10 to 30 degrees, and a cylindrical lens 9 for condensing light is arranged between the aperture 6 and the platen 1 to condense light on the two sides of the document. A device in which the irradiated light from the aperture 6 is focused toward the portion M via the cylindrical lens 9 has already been proposed. According to this type, since the aperture angle θ is set small, the width of the condensing part M on the second side of the document is set sufficiently narrow, and the brightness at the aperture 6 is also as shown in FIG. Although the aperture angle θ is set sufficiently high, as the aperture angle θ is small, the absolute amount of light irradiated from the fluorescent lamp 5 tends to be insufficient. This includes the problem of poor lighting efficiency.

As a means for solving such problems, for example, the method disclosed in Japanese Patent Application Laid-Open No. 164362/1983 has been proposed.

In this method, a light source body is provided with a plurality of openings, and the light from the openings that goes directly toward the document surface is focused via a cylindrical lens onto a condensing section on the document surface.
The light from other openings is focused onto a light condensing portion on the document surface via a condensing reflector.

However, in this type, the light from the other openings is guided toward the condensing reflector while being sequentially reflected by the waveguide formed around the light source, so the light from the other openings is The amount of light attenuation is large, and the light from the light source cannot be used effectively.In addition, the light from one opening passes through the cylindrical lens to the condensing part on the document surface, and the light from the other aperture goes to the condensing reflector. There will inevitably be a difference in light intensity between the light that goes to the condensing part on the document surface through the
A technical problem has been found in that illuminance unevenness occurs in the scanning direction of the light condensing section on the document surface.

The present invention has been made to solve the above technical problems, and even if a light source with low power consumption is used, the illumination efficiency at the light condensing part on the document surface can be improved. The object of the present invention is to provide a slit exposure apparatus that can maintain extremely good illumination uniformity in a light condensing section.

[Means for Solving the Problems] That is, in the present invention, an illumination means is disposed below a transparent platen so as to be relatively movable, and the illumination means is used to illuminate the original placed on the platen. The illumination means is based on a slit exposure device that illuminates the original in a slit shape from one end to the other and sequentially projects slit-shaped partial images of the document onto a predetermined photosensitive surface via an imaging means. a first aperture with a small aperture angle that is disposed close to a plane perpendicular to the center of the light condensing part on the document surface and facing the light condensing part on the document surface; and a first aperture spaced apart from the first aperture. a light source body having a second aperture with a small aperture angle that is arranged and substantially opposite to a plane perpendicular to the center of the light condensing part on the document surface, and which diffusely irradiates light from each aperture; a condenser lens arranged opposite to the aperture of the document surface to focus the irradiated light from the first aperture toward a condenser section on the document surface; and a light source on a surface perpendicular to the center of the condenser section on the document surface. a concentrator disposed close to the opposite side of the body, facing the second opening of the light source body, and condensing and reflecting the irradiated light from the second opening toward a condensing section on the document surface; The light reflector is also provided with a light reflector.

In such technical means, it is sufficient that each aperture of the light source body has a small aperture angle, but considering the optical path length, the aperture angle of the second aperture is smaller than that of the first aperture. By making the aperture angle slightly larger, it is possible to more accurately adjust the balance of the amount of light on the left and right sides of the light condensing section on the document surface.

[Operation] According to the above-mentioned technical means, the high-intensity light from the first aperture with a small aperture angle of the light source is focused from one side of the condenser on the document surface via the condenser lens. incident.

On the other hand, the bright light from the second aperture with a small aperture angle of the light source is immediately guided to the condensing reflector via the shortest path, and is focused from the other side of the condensing part on the document surface through this condensing reflector. do.

At this time, the incident angle of the light that enters the light condensing part on the document surface from both sides is approximately close to the plane orthogonal to the light condensing part on the document surface, so the incident light is unnecessarily reflected on the platen surface. Never.

Therefore, the high-brightness light from each opening of the light source body is efficiently irradiated with a substantially uniform light amount to the condensing portion on the document surface with little loss of light amount.

〔Example〕

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

The embodiment shown in FIG. 1 is an application of the present invention to a document moving type slit exposure device, and the basic configuration of this slit exposure device is the same as the conventional one.
A movable platen 1 on which a document 2 is placed; an illumination means S fixedly disposed below the platen 1 for illuminating the document 2 on the platen 1 in a slit shape; an imaging lens 3 that sequentially projects partial images of the original document 2 onto a predetermined photosensitive surface 4;
We are preparing for this.

In this embodiment, the illumination means S has a fluorescent lamp 5 as a light source along one side of the platen 1, and this fluorescent lamp 15 has a reflective film on the inner wall of the tube, as in the conventional case. A fluorescent paint 15a is applied through a tube (not shown), but unlike the conventional one, two openings 16a and 16b for light irradiation are spaced apart in the longitudinal direction of the tube inner wall of the fluorescent lamp 15. It is formed. These openings 16a, 16
In both cases, the reflective film and the fluorescent paint 15a are partially peeled off, and the first opening 16a faces the condensing part M on the second side of the document and has a small opening angle θa of about 10 to 30°. On the other hand,
The second opening 16b opens toward the condensing section M of the second surface of the original in the direction along the second surface of the original, and has a small opening angle θb of about 15 to 45 degrees.

A cylindrical lens 19 serving as a component of the illumination means S is disposed at a portion facing the first opening 16a, and this cylindrical lens 19 is connected to the light condensing portion M on the second surface of the original.
The illumination light from the first opening 16a is focused toward the first opening 16a. Further, a condensing reflector 18 as a component of the illumination means S is disposed at a portion facing the second opening 16b, and this condensing reflector 18 condenses light on the two sides of the document. The second opening 1 toward the section M
The irradiation light from 6b is focused and reflected.

Further, in this embodiment, the condensing part M on the second surface of the document is located on the optical axis plane X of the imaging lens 3, and the fluorescent lamp 15 and the condensing reflector 18 are located on the optical axis They are arranged facing each other with X as the boundary, and are arranged close to the optical axis plane X at a distance of about 2 to 5 mm. Note that the reference numeral 17 is a lamp heater.

Therefore, according to the slit exposure apparatus according to this embodiment, when the fluorescent lamp 15 emits light during exposure, the first and second openings 16a, 16b are opened.
The irradiated light from the first opening 16a is focused on the condensing part M on the second side of the document via the cylindrical lens 19, while the irradiated light from the second opening 16b is focused. After being reflected by the light reflector 18, the light is focused onto a light focusing portion M on the second side of the document. At this time, since the first and second openings 16a and 16b are opened with small opening angles θa and θb, respectively,
Along with the light condensing action of each light condensing member, the width dimension of the condensing part M on the second side of the document is sufficiently narrow, and as shown in FIG. 5, the brightness of each opening 16a, 16b is also sufficiently high. is set as . On the other hand, each opening 1
Although the amount of light emitted from the fluorescent lamps 6a and 16b is not so large due to the small aperture angles θa and θb, the absolute amount of light emitted from the fluorescent lamp 15 is
Since it is given by the sum of the amount of light emitted from the fluorescent lamps 15a and 16b, there is no concern that the absolute amount of light emitted from the fluorescent lamp 15 will be insufficient. Therefore, if
Even if a fluorescent lamp 15 with relatively low power consumption is used, each opening 16a, 16b has high brightness.
The irradiated light reaches the light condensing part M having a narrow width with a sufficient amount of light, and a sufficiently high illuminance can be obtained in the condensing part M. Since the partial image of the document 2 in the condensing section M thus illuminated is projected onto a predetermined photosensitive surface 4 via the imaging lens 3, the illuminance of the projected image is also given as sufficiently high. .

Further, in this embodiment, the fluorescent lamp 1
5 and the light condensing reflector 18 toward the condensing part M, considering the positional relationship between the two, the light enters the condensing part M at a small incident angle φ ₁ with respect to the plane (corresponding to the optical axis X) perpendicular to the center of the condensing part M on the second side of the document , φ ₂ , so
The situation in which the intensity of the light heading toward the condensing section M is greatly attenuated when passing through the platen 1 is also effectively prevented.

In order to confirm the above-mentioned effect, in the configuration shown in FIG.
An illumination experiment was conducted with the small aperture angle θb of b being 20 degrees, the cylindrical lens 19 made of an acrylic round rod with a diameter of 10 mm, and the condensing reflector 18 made of polycarbon resin coated with aluminum vapor deposition. The results shown in FIG. 2A were obtained as the light intensity distribution near the light condensing section on the second side of the original. According to this, it has been found that the illumination light is focused in an extremely narrow range on the two sides of the document, and that a very high and stable amount of light can be obtained at the condensing section.

For comparison, we conducted a similar illumination experiment using the conventional type (with condensing reflector 8) shown in Fig. 3, and the light intensity distribution near the condensing part on the second side of the original is shown in Fig. 2 (b). The following results were obtained. According to this, the light intensity distribution near the light condensing part is just a gentle convex shape, so the width dimension of the light condensing part is not sufficiently narrowed, and furthermore, the light quantity of the light condensing part is also at the second level.
It turned out that this was only about 65% of what was shown in Figure A. Furthermore, when we conducted a similar illumination experiment using the conventional type shown in Figure 4, we found that the original 2
The results shown in FIG. 2C were obtained as the light intensity distribution near the light condensing part of the surface. According to this, although the width dimension of the light condensing part has become narrower to some extent, it has been found that the amount of light in the light condensing part is only about 50% of that shown in Figure 2A. From this result, it is clear that the illumination efficiency of the slit exposure apparatus according to the above example is superior to that of the conventional type.

In the above embodiment, the fluorescent lamp 15 is used as the light source, but the light source is not limited to this and may be selected as appropriate.
Furthermore, the positions of the openings 16a and 16b of the fluorescent lamp 15 are not limited to those shown in the above embodiments, and may be changed in design as appropriate. Furthermore, the arrangement and specific configuration of the fluorescent lamp 15, condensing reflector 18, etc. are not limited to those shown in the above embodiments, and of course the design can be changed as appropriate. Furthermore, in the above embodiment,
Although the present invention is applied to a document moving type slit exposure apparatus, it goes without saying that the present invention can also be applied to other types of slit exposure apparatus.

〔Effect of the invention〕

As described above, according to the slit exposure apparatus according to the present invention, the brightness of the light source can be set high while ensuring a sufficient amount of light irradiated from the light source, and the light can be focused with a narrow width on the document surface. Since the light emitted from the light source is efficiently focused toward the document surface, even if a light source with relatively low power consumption is used, the illuminance of the condensing section on the document surface can be set to a sufficiently high level. becomes possible, and
It is possible to improve the illumination efficiency in the light condensing section on the document surface.

In particular, in the present invention, since the high-intensity light from each aperture with a small aperture angle in the light source body is irradiated onto the condensing portion of the document surface from both sides with a substantially uniform light intensity, It is possible to maintain extremely good illumination uniformity in the light condensing section.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram showing one embodiment of the slit exposure device according to the present invention, and FIG. 2 shows the light intensity distribution characteristics near the condensing part on the document surface obtained in the slit exposure device according to the present invention and the conventional type. FIG. 3 is a cross-sectional explanatory view showing an example of a conventional slit exposure apparatus, FIG. 4 is a cross-sectional explanatory view showing another example of a conventional slit exposure apparatus, and FIG.
The figure is an explanatory diagram showing the relationship between the aperture angle of the aperture of a fluorescent lamp and the relative brightness of the aperture. [Explanation of symbols], M: condensing section, S: illumination means,
θa, θb...Small opening angle, 1...Platen, 2...
Original, 3...imaging lens, 4...photosensitive surface, 15...
... Fluorescent lamp (light source), 16a... First opening, 16b... Second opening, 18... Condensing reflector, 19... Cylindrical lens (condensing lens).

Claims (1)

[Claims] 1. Illumination means is disposed below a transparent platen so as to be relatively movable, and the illumination means illuminates a document placed on the platen in a slit shape from one end to the other end. In the slit exposure apparatus, the slit-shaped partial images of the document are sequentially projected onto a predetermined photosensitive surface via an imaging means, the illumination means being perpendicular to the center of the condensing part on the document surface. a first aperture with a small aperture angle, which is disposed close to the surface of the document surface, and which faces the light condensing section of the document surface; a light source body having a second aperture with a small aperture angle substantially facing perpendicular planes and emitting light from each aperture in a diffused manner; a condensing lens that focuses the irradiated light from the first opening toward a condensing section of the document; , comprising a condensing reflector that is disposed opposite to the second opening of the light source and that condenses and reflects the irradiated light from the second opening toward a condensing section on the document surface. slit exposure equipment. 2. The slit exposure apparatus according to claim 1, wherein the aperture angle of the second aperture is slightly larger than that of the first aperture. 3 The aperture angle of the first aperture of the light source is 10 to
The opening angle of the second opening is set to about 30°, and the opening angle of the second opening is 15°.
A slit exposure apparatus according to claim 1 or 2, characterized in that the angle is set at about 45 degrees.