JPH09191368A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read a reflecting original and a transparent original with the reader in which miniaturization and cost-reduction are realized and power consumption is reduced by using an existing optical system is used in common to read a reflection original and deteriorated resolution and uneven luminous quantity distribution are prevented. SOLUTION: In the case of reading a film original F, 1st and 2nd carriages 19, 20 are not moved and the 1st carriage 19 is at a standstill at a position of a reference white board 12 and a light of a light source 13 reflected in the reference white board 12 is reflected in a 1st mirror 14 and a 2nd mirror 15 to light up the film original F behind it. The light transmitted through the film original F is reflected in a 3rd mirror 16 and the image is formed by a lens 17 and photoelectric-converted by a CCD line image sensor 18. As a result, when the film original F moves between the 2nd mirror 15 and the 3rd mirror 16, the original is scanned in a subscanning direction and the original is scanned by the CCD line image sensor 18 in the main scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device for reading a reflection document and a transparent document, and more particularly to a document reading device suitable for a copying machine, especially a color copying machine.

[0002]

2. Description of the Related Art Various conventional methods for reading both reflective originals and transparent originals include, for example, (1) JP-A-59-198439 (2) JP-A-2-287528 (3) Ricoh Co., Ltd. Slide projector unit (trade name: "Puritail 750") (4) Japanese Patent Laid-Open No. 2-91630 is known.

In the above (1), a projector (lamp, lens, mirror, casing, etc.) for enlarging and projecting a film image on the entire surface of the original plate of the copying machine is installed outside the copying machine, and the above (2) In (3), the film is configured to be scanned in a slit-like shape in the sub-scanning direction by a special scanning mechanism, and in (4) above, a backlight system is proposed in which the film is directly placed on the original table and illuminated from behind. There is.

[0004]

However, in the above (1), a projector for enlarging and projecting the film image on the entire surface of the original plate of the copying machine is separately required.
The cost is high, and the power consumption for turning on the lamp of the projector is large, which causes a problem of heat generation. Further, since the image is projected on the entire surface of the original table of the copying machine, unevenness occurs in the two-dimensional illuminance distribution, and this problem cannot be solved.

In the above (2) and (3), since the film is scanned like a slit in the sub-scanning direction, the amount of light is small, and the unevenness of the illuminance distribution may be corrected by shading only in the length direction of the slit. It requires a special scanning mechanism and is expensive. The backlight method of (4) above has an advantage that the configuration is relatively simple,
Since the original is small (35 mm), the resolution will be significantly reduced if it is electronically scaled and enlarged on the digital copying machine side.
There is a problem of uneven light intensity distribution.

In view of the above-mentioned problems of the prior art, the present invention also serves as an existing optical system for reading a reflection original, thereby achieving downsizing, cost reduction, and power consumption reduction, as well as reduction in resolution and uneven light amount distribution. It is an object of the present invention to provide a document reading device for a reflective document and a transparent document that can prevent the above-mentioned problems.

[0007]

To achieve the above object, the present invention provides a light source for illuminating a reflection original, an optical system for forming an image of reflected light of the reflection original illuminated by the light source, and the optical system. A photoelectric conversion element for reading the main scanning direction of the reflective original by photoelectrically converting the reflected light imaged by
And a transparent original conveying means for moving the transparent original in the sub-scanning direction at right angles to the optical axis of the optical system.

Further, the lens of the optical system or the photoelectric conversion element is moved in the optical axis direction so that each image is formed on the light receiving surface of the photoelectric conversion element at the time of reading the reflective original and the reading of the transparent original. Is characterized by.

Further, a reference white plate for shading correction is provided on the contact glass on which the reflective original is placed, and the light source illuminates the reference white plate when reading the transparent original.

Further, a reference white plate for shading correction is provided on the contact glass on which the reflective original is placed, and when reading the transparent original, the shading correction is performed based on the read value of the reference white plate.

Further, the sub-scanning direction of the transparent original is scaled by changing the moving speed of the transparent original conveying means.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a configuration diagram showing an embodiment of a document reading device according to the present invention, FIG. 2 is an external view of the document reading device of FIG. 1, FIG. 3 is a configuration diagram showing a transport mechanism of the film document of FIG. 1, FIG. FIG. 3 is an explanatory view showing positions of the lens of FIG. 1 at the time of reading a reflective original and at the time of reading a film original.

In FIG. 1, a contact glass 11 is used for placing a reflection original, and a reference white plate 12 for shading correction is provided. The reflection original on the contact glass 11 and the reference white plate 12 are illuminated by the light source 13, and the light reflected downward is reflected by the first mirror 14.
Is reflected at a right angle in the horizontal direction by the second mirror 1
5 is reflected at a right angle downward and then the third mirror 1
6 at a right angle to the horizontal direction, and then the lens 17
Is image-formed by the CCD line image sensor 18 and photoelectrically converted by the CCD line image sensor 18.

The light source 13 and the mirror 14 are the first carriage 1
9, the mirrors 15 and 16 are mounted on the second carriage 20.
It is installed in. Then, when reading the reflective original, the first carriage 19 moves in the horizontal direction (sub-scanning direction) at a speed half that of the second carriage 20. That is, these optical systems 11 to 20 are general document fixed / optical system movable type scanners that read a reflective document. However, the lens 17 is configured to move to a different position in the optical axis direction and stop during reading of a reflective original and reading of a film original.

In this example, as shown in detail in FIG. 3, the rollers 1 to 4 for moving the film original F between the second mirror 15 and the third mirror 16 in the sub-scanning direction obstruct the optical path of the reflection original. In this example, the optical paths of the reflection originals are provided so as to cross each other at predetermined intervals in the horizontal direction so as not to exist. The roller 1 is connected to a drive system 5, and a belt 6 is suspended on the rollers 1 to 3 and rotated by the drive system 5.

On the rollers 1 to 4, a film mounting table 21 for mounting the film original F is provided so as to be movable in the horizontal direction as the rollers 1 to 3 rotate. As shown in Figure 2, the film insertion / ejection port 2
The film original F can be placed via the sheet 2. The roller 4 is in a free state and the film mounting table 21
Also, the film original F is driven by the movement thereof, and the film placing table 21 and the film original F are prevented from dropping.

In such a structure, the film original F
When reading, the first and second carriages 19 and 20 do not move, the first carriage 19 stops at the position of the reference white plate 12, and the light of the light source 13 reflected by the reference white plate 12 is reflected by the first mirror 14 and the second mirror 14. It is reflected by the mirror 15 and illuminates the film original F from behind. Then, the film original F
The light transmitted through is reflected by the third mirror 16 and focused by the lens 17, and the CCD line image sensor 18
Is subjected to photoelectric conversion. Therefore, when the film original F moves, it is scanned in the sub-scanning direction, and the main scanning direction is scanned by the CCD line image sensor 18.

Here, the reflection original surface, the surface of the film original F, the light receiving surface of the CCD line image sensor 18 and the respective positions of the lens 17 are designed so as to form an image at a predetermined magnification. That is, even if the film original F is placed between the second mirror 15 and the third mirror 16 of the existing reflection original reading optical system, the lens 17 does not form an image on the light receiving surface of the CCD line image sensor 18 as it is. The document F is moved to a position where an image is formed.

FIG. 4A shows the state of FIG.
(B) shows the relationship among the document, the lens, and the image forming position when reading the film document. In addition, as an example, FIG.
In (a), the width (about 300 mm, 150 mm on one side of the optical axis) in the lateral direction (main scanning direction) of the reflection original of A3 size is reduced 0.22 times by the lens 17 to about 66 mm (one side of the optical axis). Shows a case of forming an image on the light receiving surface of the CCD line image sensor 18 with a length of 33 mm).

In this case, the focal length of the lens 17 is 78 m
lens 17 is 420 mm from the reflection original, CC
It is located 93 mm from the D-line image sensor 18. Further, as the CCD line image sensor 18, it is possible to use one having a size of each pixel of 14 μm × 14 μm and a number of 5000 and a length of 70 mm (> 66 mm).

On the other hand, FIG. 4 (b) shows an example of 35
A case where a film original F having a size of mm is read at a magnification of 1 by the common lens 17 is shown. In this case, when the lens 17 is moved 63 mm toward the film original F, the lens 17 is located at a distance of 156 mm from both the film original F and the CCD line image sensor 18. The film original F
The positions of the lens 17 and the lens 17 are not limited to these numbers, and can be appropriately changed according to the length of the CCD line image sensor 18. Further, the film original F may be read by enlarging it, and it is possible to read not only 35 mm but also 4'x 5'film.
Further, instead of moving the lens 17, the CCD line image sensor 18 may be moved. Further, not only the original fixed / optical system moving type scanner but also the original moving / optical system fixed type can be applied. You can

Therefore, according to the present invention, since the existing reflection original reading optical systems 11 to 20, especially the light source 11 and the lens 17, are also used, the color correction such as γ correction and the color conversion processing circuit are negative. There is no need to provide it separately except for a film. Further, the reference white plate 12 is generally stored for each pixel of the CCD line image sensor 18 before reading the reflective original, and the read value of each pixel of the reflective original is divided by the read value of each pixel of the reference white plate 12. The reference white plate 1 is used to perform so-called shading correction for correcting unevenness of the light amount of the light source 11 in the main scanning direction, unevenness of sensitivity of each pixel of the CCD line image sensor 18, and the like.
The read value of each pixel 2 can be stored and used also when reading the film original F.

Further, by moving the lens 17 in the optical axis direction and changing the moving speed of the film original F, it is possible to easily perform the magnification change in the main scanning direction and the sub-scanning direction, respectively. Here, when the reflection original is enlarged in the main scanning direction, it is usually electrically performed by interpolating pixels, but since the enlargement of the film original F in the main scanning direction can be performed by the lens 17, it is electrically changed. Unlike double magnification, the number of pixels is increased by the lens 17, so that a clear image quality can be obtained as in the case of stretching silver halide photographs.

Finally, in comparison with the projection type conventional example, this projection type originally enlarges and projects a small photographic film on the large original table of the copying machine by the magnifying lens optical system of the projector, and further reduces the lens size of the copying machine. Since this is a system in which the image is reduced by the system and read by the CCD line image sensor 18, defocusing, image quality deterioration due to MTF, and light amount decrease due to the F value of the lens occur due to the two-system lens optical system. However, the present invention has an advantage that such a problem is small because the reading is performed by one lens optical system.

[0025]

As described above, according to the present invention, the transparent original is moved in the sub-scanning direction at right angles to the optical axis of the optical system for reading the reflective original. The existing optical system is also used for downsizing, cost reduction, power consumption reduction, and resolution reduction.
It is possible to prevent uneven light amount distribution.

Further, the lens of the optical system or the photoelectric conversion element is moved in the optical axis direction so that each image is formed on the light receiving surface of the photoelectric conversion element during reading of the reflective original and reading of the transparent original. Even if the transparent original is moved in the sub-scanning direction at right angles to the optical axis of the optical system, the image can be reliably formed, and the main-scanning direction can be magnified.

Further, a reference white plate for shading correction is provided on the contact glass on which the reflective original is placed, and the light source illuminates the reference white plate when the transparent original is read. It is not necessary to provide a circuit for color conversion or the like, so that it is possible to reduce the cost and reduce the trouble of setting the correction parameter.

Further, a reference white plate for shading correction is provided on the contact glass on which the reflective original is placed, and when the transparent original is read, the shading correction is performed based on the read value of the reference white plate, so that the transparent original is read. Therefore, a memory for shading correction and the like can be omitted separately, and the labor for designing the control sequence and the labor for shading compensation for the operator can be omitted. Further, since the sub scanning direction of the transparent original is scaled by making the moving speed of the transparent original variable, it is possible to prevent the resolution from being lowered at the time of enlargement.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a document reading apparatus according to the present invention.

2 is an external view of the document reading apparatus in FIG.

3 is a configuration diagram showing a transport mechanism for the film original of FIG. 1. FIG.

FIG. 4 is an explanatory diagram showing positions of the lens of FIG. 1 when reading a reflective original and when reading a film original.

[Explanation of symbols]

 F film original 1 to 4 roller 5 drive source 11 contact glass 12 reference white plate 13 light source 14 to 16 mirror 17 lens 18 CCD line image sensor 21 film mounting table 22 film insertion / ejecting port

Claims (5)

[Claims] 1. A light source for illuminating a reflection original, an optical system for forming an image of the reflected light of the reflection original illuminated by the light source, and a reflection original by photoelectrically converting the reflected light formed by the optical system. An original reading apparatus having a photoelectric conversion element for reading the main scanning direction and a transparent original conveying unit for moving the transparent original in the sub-scanning direction orthogonal to the optical axis of the optical system. 2. The lens of the optical system or the photoelectric conversion element is moved in the optical axis direction so that each image is formed on the light receiving surface of the photoelectric conversion element during the reading of a reflective original and the reading of a transparent original. The document reading device according to claim 1, wherein: 3. A reference white plate for shading correction is provided on a contact glass for mounting a reflection original, and the light source illuminates the reference white plate when a transparent original is read. The document reading device described. 4. A reference white plate for shading correction is provided on a contact glass on which a reflective original is placed, and shading correction is performed based on a read value of the reference white plate when reading a transparent original. The document reading device according to any one of items 1 to 3. 5. The document reading device according to claim 1, wherein the moving speed of the transparent document conveying means is made variable so as to change the magnification of the transparent document in the sub-scanning direction. .