JPS58132260A - Copying machine - Google Patents

Abstract

PURPOSE:To obtain copy images of high quality of arranging plural Fresnel lenses one over another in or near the plane of an air image, and using a cylindrical Fresnel lens having an axis crossing a scanning direction as one of said Fresnel lenses and allowing it to move. CONSTITUTION:Fresnel lenses 10 and 11 are arranged in or near the image formation surface of a projection lens 7 and enlarged projection light from the projection lens 7 is converged to enter an image forming lens 7 arranged in a copying part 2. The upper Fresnel lens 10 consists of the cylindrical Fresnel lens having the axis perpendicular to the scanning direction (a) and is large enough to allow entire-picture light to be copied to strike the lens at the same time; the lower Fresnel lens 11 consists of the cylindrical Fresnel lens having the axis crossing the scanning direction (a) and is formed in a long and thin slit shape to allow the incidence of only part of the picture light. The Fresnel lenses 10 and 11 have the lens surfaces facing each other to reduce the loss of the quantity of transmitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for obtaining a copy image from an aerial alt-original image by slit exposure. In this apparatus, copies are made using reflected light from a document placed on a document table. When copying is performed using transmitted light from a microfilm or other transparent original, a copying machine of a size large enough to receive an aerial image over the entire surface of the original plate is used, as shown in Japanese Patent Publication No. 46-24187. Two Fresnel lenses are fixedly installed, and an enlarged image of the microfilm is projected onto the two Fresnel lenses.
The aerial image formed on the Fresnel lens is focused by a 7-resnel lens toward the center of an imaging lens of a copying device, and the light emitted from the imaging lens is projected onto a photoreceptor to obtain a copied image. However, this method uses two large 7-lens lenses, which is expensive and heavy, and there are problems in that the quality of the copied image deteriorates.

Figure 1, tm, (c) explains the state of light transmission through a 7-Lenel lens. Figure 1, Figure 1, (When a beam of light enters from the back surface of the 7-Lenel lenses l and 1' as shown in Bl, When a beam of light is incident on the lens-constituting surface (a surface with a sawtooth cross section) of a 7-lens lens 1' as shown in Fig. 1c), the emitted beam refracted by the lens is L'. There is no emitted light in the shaded area in Figure 1. The reason for this is that among the surfaces constituting the lens in a 7-Renel lens, the lens surface 1, which effectively contributes to the lens surface,
This is because almost no emitted light travels in the same direction as the emitted light beam L' due to refraction at the connecting surface 1b other than m.

For this reason, when making a positive copy image from positive film using electrophotography, 1. This area (the shaded area in FIG. 1) has a problem in that black smudges appear on the copy paper and the quality of the copied image deteriorates. 7 The quality of the reproduced image can be improved to some extent by reducing the pitch of the grooves of the Fresnel lens, but if two Fresnel lenses are stacked so that their rings intersect, The area near the intersection of the connecting surfaces appears as a black dot on the copy paper,
In either case, there was a problem that the quality of the image deteriorated. Furthermore, when making a positive copy image from a cinema film using the reversal development method of electrophotography, white streaks or white dots appear in the image area (black area) on the copy paper, which also affects the quality of the copy image. There was a problem that the value decreased.

The present invention aims to solve the above problems and obtain high quality copied images.

The present invention will be explained below with reference to the drawings.

The second diagram shows a copying apparatus according to an embodiment of the present invention, and this apparatus is also called a film printer. This copying device is composed of a film projection section l and a copying section 2,
The film projection section 1 is arranged above the copying section 2. The film projection section l includes an illumination light source 3, a condenser lens 4,
It has transparent plates 5 and 6 that hold the microfilm F between them, and a projection lens 7 that enlarges and projects the image of the microfilm F.

The microfilm F is movable in a predetermined direction, but when copying, it remains stationary at the position shown in the figure and is illuminated by light from a light source 3 through a condenser lens 4. A 7-lens lens lO. placed above the copying section 2 by the projection lens 7.
It is projected towards 11.

The 7-Renel lens 10.11 is arranged at or near the imaging plane of the projection lens 7, and focuses the enlarged projection light from the projection lens, and directs this focused light to the imaging lens arranged in the copying section 2. It allows the light to be incident.

As shown in FIG. 3, the upper Fresnel lens lO is a cylindrical Fresnel lens having an axis perpendicular to the scanning direction a, and has a relatively large shape that allows all the image light to be copied to be incident at the same time. F section's 7 Lenel lens l1 scanning direction a
It is a cylindrical 7-Resnel lens with an axis that intersects with the 0.0 Fresnel lens, which has a slit-like elongated shape that allows only a portion of the total image light to enter. The lens surfaces of the lenses are arranged to face each other.
The upper Fresnel lens 10 is fixed to the copying unit 20 case, and the lower Fresnel lens 11 moves back and forth at a constant speed along the upper Fresnel lens 10 in the scanning direction a.

In the copying section 2, various known means for forming a copy image are arranged.

A first reflecting mirror 12 is arranged below the Fresnel lens 11 in the 4IL'4 section 20 case, and a second reflecting mirror 13 is arranged opposite to the first reflecting mirror 12.

The first reflecting mirror 12 moves in the forward direction a from the solid line position shown in the figure at an appropriate constant speed together with the Fresnel lens 11 so as to scan the projected image of the microfilm F.
Also, the second reflecting mirror 13tj, the first reflecting mirror 12
It moves in the same direction at half the speed of. Then, the image scanned by the first reflecting mirror 12 passes through the second reflecting mirror 13 and enters the imaging lens 14 ←], and further passes through the fixed reflecting mirrors 15 and 16 and the slit member 17 S, and then passes through the electrophotographic photosensitive drum 18. projected on. Photosensitive drum 18F
It rotates at a speed corresponding to the scanning speed of the i111 reflecting mirror 12. When the scanning in all directions of the image is completed, the 7-Renell lens 11, the first reflecting mirror 12, and the second reflecting mirror 13 move back from the broken line position to the original solid line position.

The 7-Renell lens 11 and the reflecting mirrors 12, 13-15, and 16 have a length longer than the length of the image in the direction perpendicular to the scanning direction.

A charging device 2G, a developing device 21, a transfer charging device 22, and a cleaner 23 are provided around the photosensitive drum 18, respectively. 25 is a paper feeding roller that feeds one sheet of transfer paper from the paper sheet 25;
Reference numeral 7 denotes a conveyance belt that conveys the transfer paper on which the toner image on the photosensitive drum 18 has been transferred to the heat fixing device 2B, and a transfer paper discharge tray 29#i.

The imaging lens 14 is at the same magnification at the solid line position shown in the figure. Therefore, the aerial image formed near the 7 renel lens 1° 11 is at the same magnification by the imaging lens 14 and is then transferred to the photosensitive drum. 18.

7/' In the above apparatus, when a positive film is used as the microfilm F and an image on the microfilm is to be copied, the 7-lens V lens 11 and the first reflecting mirror 12 are moved around the circumference of the photosensitive drum 18 from the solid line position shown in the figure. The second reflecting mirror 13 is moved in the forward scanning direction 1 at a speed of -v. The projected image on the microfilm F is focused on the imaging lens 14 by the 7-lens lenses 10 and 11, and the focused 9-image Kenko is charged by the charger 20 and projected onto the photosensitive drum 18.

Here, as shown in FIG. 4, the intersection angle between the axis of the lower cylindrical Fresnel lens 11 and the scanning direction 1 is θ(0
0), if the cylindrical Fresnel lens 11 is provided,
During the copying operation, the cylindrical Fresnel lens 11 moves at a constant speed in the scanning direction aK, so that the missing portion of emitted light caused by the connecting surface IAK, which causes deterioration in the quality of the copied image, appears on the photosensitive drum 18 in a well-blurred state. When it is projected, as a result, the photosensitive drum 18 df & i. On the other hand, the missing part of the emitted light due to the connecting surface of the upper cylindrical Fresnel lens 10 is projected onto the photosensitive drum 18 without blurring, but it is possible to prevent the occurrence of black spots by making the pitch of the Fresnel lens finer. In addition, regarding the influence of the intersection of the connecting surfaces of both Fresnel lenses 10 and 110, since the axis of the lower Fresnel lens 11 is unclearly projected onto the photosensitive drum, no black dots will be produced on the photosensitive drum. Deterioration in the quality of the copied image is prevented.

The electrostatic latent image on the photosensitive drum 18 is developed with toner from a developing device 21, and this toner image is transferred onto transfer paper fed by a paper feed row 26. The transfer paper on which the toner image has been transferred is heated and fixed in the fixing device 28, and then transferred to the tray 2.
It is discharged at 9. The remaining toner on the photosensitive drum 18 is cleaned by a cleaner 23, and the photosensitive drum 18 can be used repeatedly. Copy #! formed on the transfer paper using the above device! The 7-Resnel lens 1o/11 produces a black sushi, and a high-quality copy image can be obtained without producing black spots.0 Note that the intersection angle of the axis of the cylindrical Fresnel lens 11 with respect to the scanning direction is -, and the 7-Resnel lens When the pitch (distance between grooves) is P, and the effective @ (length in the scanning direction) of the slit 8 of the slit member 17 is L, then θ = age - (where n is an integer) holds true. do. This intersection angle θ becomes the state shown in FIG. 4 when n=1, and the state shown in FIG. 5 when n=2.If On is increased, the intersection value becomes large. can be distributed and projected in the axial direction of the photosensitive drum, and a similar effect can be obtained. However, if n becomes large, the image will be distorted, so it is better not to make the remainder large. This is effective when the slit member is placed near the photosensitive drum and the projected image of the microfilm is scaled by the focusing lens 14 and projected onto the photosensitive drum, or when the slit member is placed in the middle of the optical path. @L is the effective width of the slit that would be required if the slit member was placed near the 7-Resnel lens 11.0 As the fixed 7-Resnel lens 10, an ordinary Fresnel lens with a large number of concentric circles with a sawtooth cross section is used. You may also use the Fresnel lens 11 and the Fresnel lens 10.
It is good to place it on top of the book. If a negative film is used as film F and a positive copy image is created by the reversal development method, a high-quality copy image can be obtained as described above.The copy original can be used not only for transparent originals such as film, but also for documents, etc. It is also possible to use a reflective original and copy the reflected light image of the original by projecting it onto a Fresnel lens.

In the above apparatus, the film projection section 1. The Fresnel lenses 10 and 11 are arranged as desired in the case of the copying section 2,
Remove these from the case, place a transparent glass plate in the place where the 7-lens lens 10 has been placed, place an original such as a document on this glass plate, and place this original on the first reflecting mirror. By illuminating with an illumination lamp that moves integrally with 12, it can be used as a normal copying device0. As the copying method, various known copying methods can be adopted in addition to the embodiments.0 According to the present invention, one of the Fresnel lenses can be made smaller and lighter, and furthermore, a high quality copy image can be obtained.

[Brief explanation of the drawing]

1(A), (B), and (0) are diagrams illustrating the incident light flux and the exiting light flux of a 7-Renel lens; FIG. 2 is a configuration diagram showing one embodiment of a copying apparatus to which the present invention is applied; Figure 3 is the main engine 1
Perspective view of a set of 7 renel lenses used in jlK, 4th
The figure is a diagram for explaining the intersecting state of the axis of the cylindrical Fresnel lens and the scanning direction, and FIG. 5 is a diagram for explaining the intersecting state when n = 2. Fresnel lens 12, 13, 15, 18-...Reflector 14...
・Muirin Lens 18...Photosensitive drum (A) Procedural amendment form (voluntary) 1. Indication of the case: Patent Application No. 14542, 1977 2. Name of invention copying device 3. Person making the amendment Relationship with the case: Patent applicant Location: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo ( telephone 7
5g-2111) Column 6 of ``Detailed Description of the Invention'' in the Specification, Contents of Amendment (1) Page 11 of the Specification, Line 7, 1 - Amend 'p J to 1' A) 4.

Claims (1)

[Claims] (+1) In an apparatus that copies an aerial image obtained by projecting an original image as an original image by slit exposure,
A plurality of Fresnel lenses are arranged one on top of the other on or near the plane of the aerial image, one of which is a cylindrical 7-Renel lens having an axis that intersects with the scanning direction, and the cylindrical 7-Renel lens is moved. A copying device that uses (2) When the slit width is L1 when the slit member is arranged near the aerial image plane, and the pitch of the grooves of the cylindrical 7-Renel lens is P, the intersection angle θ between the axis and the scanning direction is θ=-sin1nP. (n is a positive integer) The copying apparatus according to claim 1, wherein n is a positive integer. (3) The cylindrical 7-Renel lens moves back and forth at a constant speed.
Copying device as described in section. (4) The copying apparatus according to claim 1, wherein the 7-Lesnel lenses other than the cylindrical 7-Lessnel lens are cylindrical Fresnel lenses having an axis perpendicular to the scanning direction.