JPS6052819A - Reader - Google Patents

Abstract

PURPOSE:To read faithfully an image by forming the projected image from an original picture and the original image from an original via telecentric optical system on a solid state image sensing element. CONSTITUTION:The main ray from an original advances in parallel with an imaging lens 5, passes through a stop 6 and arrives arrives at a solid state image sensing element 7 in the case of reading an ordinary original. The luminous flux limited by a stop around the main ray is thus converted together with the main ray as an original image on the element 7 via a telecentric optical system 4, by which the distortion-free original image is formed. A scanning optical system 12 repeats main scanning and auxiliary scanning and reads the entire area of the original. An original picture 1 illuminated by a lamp 18 via a condenser lens 16 is magnified and projected to a Fresnel lens 3 by a projecting lens 2 in the case of reading the projected image of the original picture. The image formed on the element 7 from the lens 3 is similarly virtually distortion- free. Since the image of the original and the original picture can be faithfully read in the above-mentioned way, the neat image having no distortion is formed when said image is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reading device for a facsimile machine, an electrophotographic copying device, etc., and particularly to a reading device capable of reading a projected image of an original image projected from a projection device in addition to reading a normal document. It is something.

Conventionally, as described in Japanese Unexamined Patent Publication No. 55-137767, an image forming lens is used in the sub-scanning direction in which a document is intermittently fed (-) by using reflected light from the document on an array of solid-state image sensors. ;2) While forming a document image, move the solid-state image sensor and the imaging lens in the main scanning direction that is perpendicular to the sub-scanning direction, and perform sub-scanning by one reciprocating operation of this movement in the main-scanning direction. There are devices that simultaneously read and scan multiple lines in different directions.In addition, when reading projected images of films such as microfilm, these original images are optically scanned onto the solid-state image sensor of the reading device. The projected image is enlarged or reduced through a system, and this projected image is intermittently moved in the sub-scanning direction in the same way as the original, and the solid-state image sensor is moved in the main scanning direction in the same way as above, so that the projected image of the original image is It is possible to read it.

For the above reasons, it is possible to interpose an imaging lens in the reading device and read a normal document with a solid-state image sensor, or to remove the imaging lens from the reading device and capture the projected image of the original image on microfilm etc. in the same solid-state image. It is possible to read the element in a manner similar to that described above. Such a reading device that can perform both reading using reflected light from an ordinary document and reading using projected light from an original image has many advantages, but it is difficult to take the imaging lens in and out of the reading device. The reading mechanism becomes complicated and the reading device itself becomes large, making it impractical. Therefore, without retracting the imaging lens from the reading device, the projected image of the original image is enlarged or reduced and projected onto the reflective document surface, and the image is formed on the solid-state image sensor through this projection image lens. It is conceivable to read the projected image of the original image by scanning this solid-state image sensor using the same reading method as for reading a reflective original. However, in this case, unlike forming an original image on a solid-state image sensor using an imaging lens using reflected light from a reflective original, this same imaging lens is used to form an image projected by a projection optical system. It is impossible to form it on a solid-state image sensor because the direction of the principal ray is different from that using reflected light.

Therefore, in order to change the direction of the principal ray of the projected image, that is,
A known method is to arrange a Fresnel lens as a field lens at a position above the document surface so that light forming a projected image travels in a direction perpendicular to the document surface. However, when the projected image of the original image formed on this Fresnel lens is formed on the solid-state image sensor (= the luminous flux of the projected image incident from the end of the imaging lens) using an imaging lens of a normal optical system, not a special optical system, As a result, the original image formed on the solid-state image pickup device appears to have extremely large aberrations.

Therefore, even if an image signal is obtained by scanning a solid-state image sensor using this method, this image signal itself is not faithful to the original image, so it is impossible to faithfully reproduce the read image. .

The present invention has been made in view of the above points and in order to improve the above-mentioned drawbacks. It is an object of the present invention to provide a reading device that can faithfully read an image of an original image and/or a document, and forms an image on a solid-state image pickup device by almost eliminating the image of the original image.

An embodiment of a reading device according to the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention, FIG. 1 is a simplified diagram of a reading device according to the present invention, and FIG. 2 is a schematic cross-section of this reading device applied to a projection and reflection type reading device. It is a diagram. In the figure, 1 is an original image with an image on film, etc., 2 is a projection lens, 3 is a Fresnel lens as a field lens, and 4 is a telescopic link optical system, which has an optical axis parallel to the optical axis of Fresnel lens 3. A diaphragm 6 having an aperture is arranged at the focal point of the imaging lens 5.

A solid-state image sensor 7 made of a CCD (charge coupled device) or the like is arranged at the imaging position of the telecentric optical system 4. The Fresnel lens 3 is located at the image forming position of the projection lens 2 and has a focal point at the exit pupil of the projection lens 2. 9 is a projector, and the original picture 1 mentioned earlier,
In addition to the projection lens 2 and Fresnel lens 3, there is a condenser lens 16 placed behind the original image, an illumination lamp 18 and a reflective shade 19 placed behind this, a fan 17 for cooling these, and a flattening of the original image 1. Original picture fixed frame 15 to be held
, a holder 14 for holding the original image 1, etc., and a fixing member 2 for temporarily fixing the holder 14 on the original platen 10.
It is composed of 0. Note that the Fresnel lens 3 is arranged near the top of the document table 10. 8
1 is the main body of the reading device, which holds the document mounting table 10, the telecentric optical system 4, the fixed image sensor 7, as well as the lamp 11 for illuminating the original (2), the telecentric optical system 4, and the solid-state image sensor 7. A scanning optical system 12 is provided movably in the main scanning direction which is a perpendicular direction and intermittently movable in the sub-scanning direction of arrow A perpendicular to this.
It is composed of. This scanning optical system is guided by a rail 13 and is moved in the main scanning direction by means (2) not shown, and is also moved intermittently in the sub-scanning direction ζ2 together with the lamp 11 by means (2) not shown. Further, the direction in which the pixels of the solid-state image sensor 7 are arranged is the sub-scanning direction.

When reading a normal document, the projector 9 is
A normal original is placed on the original placing table 10 and illuminated by the lamp 11. For example, as shown by the dashed line in Figure 2 (the chief ray from the two originals is
The light beam travels parallel to the optical axis of the imaging lens 5 (passes through two apertures 6 and reaches the solid-state image sensor 7. Therefore, the light flux limited by the aperture as the center of this chief ray is transmitted through the telecentric optical system. Since the original image is converged together with the chief ray as an original image on the solid-state image sensor 7 via the solid-state image sensor 4, an undistorted original image is formed on the solid-state image sensor 7. After one reciprocating operation of the scanning optical system 12 in the main scanning direction, the scanning optical system 12 moves in the sub-scanning direction (direction of arrow A) by the reading width, and then moves in the sub-scanning direction again. Reading begins.The scanning optical system 12 repeats such main scanning and sub-scanning to read the entire area of the original on the original placing table 10.Next,
When reading the projected image of the original image, the projector 9 is placed on the reading device main body 8 and fixed via the fixing member 2o.

At this time, the relationship among the original image 1, projection lens 2, Fresnel lens 3, imaging lens 5, telecentric optical system 4, and solid-state image sensor 7 is as shown in FIG. An original image 1 illuminated by a lamp 18 via a condenser lens 16 is enlarged and projected onto a Fresnel lens 3 by a projection lens 2. The principal ray of this projected image from the Fresnel lens 3 travels in a direction perpendicular to the surface of the document table 10, that is, in a direction parallel to the optical axis of the imaging lens 5, as shown by the dashed line, and forms an image. The light enters the lens, passes through the aperture 6, and converges on the solid-state image sensor 7 together with the light flux near the chief ray. The image formed on the solid-state image sensor 7 in this way has almost no distortion because it is formed via the Fresnel lens 3 that changes the principal ray of the projected image and the telecentric optical system 4 that removes aberrations of the imaging lens. It is faithful to the original image 1. This image is captured by the scanning optical system 12 while scanning the solid-state image sensor 7 in the sub-scanning direction (direction of arrow A).
After this reciprocating operation, the scanning optical system 12 moves by the reading width in the sub-scanning direction, and reading in the main-scanning direction is started by the solid-state image sensor 7. The entire area of the projected image of the original image 1 can be read by the scanning optical system 12 repeating such sub-scanning and main scanning.

The signals read from the solid-state image sensor 7 are outputted by an electrophotographic laser beam printer, inkjet printer, thermal printer, etc. after being subjected to appropriate signal processing, and are printed as a hard copy, or printed on a cathode ray tube or liquid crystal display board. It is displayed on a display device such as, or transmitted. In addition to this, the present invention can also use an in-plane refractive index distribution type plane lens having the same configuration as a matrix array of a large number of microlenses arranged in place of the Fresnel lens.
In the reading device shown in the figure, a normal reflective original may be used instead of the original 1. In addition to this, the scanning optical system was moved two-dimensionally to perform scanning, but the original image or document mounting table was moved one-dimensionally so that it could be scanned in either the sub-scanning or main-scanning direction. , and the original image etc. may be read by moving the scanning optical system in the remaining one dimension.

As described in detail above, the present invention is capable of reading an image faithfully to the image of a manuscript or an original image, so that when this image is reproduced, a clear image without distortion can be formed.

[Brief explanation of drawings]

FIG. 1 is a simplified diagram of an embodiment of the reading position according to the present invention;
FIG. 2 is a schematic cross-sectional view of the reading device of FIG. 1, which is suitable for projection and reflection type reading devices. 1... Original image 2... Projection lens 3... Fresnel lens 4... Telecentric light 15... Imaging lens 6... Aperture 7-... Solid-state image sensor 10... Original table 12・・・
・Scanning optical system

Claims (1)

[Claims] In a reading device that reads a projected image from an original image and/or a light image of a document using a solid-state image sensor, a telecentric optical system is used as an optical system to form the projected image and/or reflected light image on the image sensor. A reading device, characterized in that the projected image is guided to a telesend link optical system via a field lens.