JPS6372263A - Picture reader - Google Patents

Abstract

PURPOSE:To attain the reading with high resolution without missing or duplication of picture information by arranging a reflection mirror in parallel with the main scanning direction and leading a picture in a prescribed range split along the main scanning direction to a photoelectric conversion element via the reflection mirror. CONSTITUTION:The photoelectric conversion element group 32 consists of 5 CCDs 38a-38e, and the CCDs 38a-38c are arranged on a line in crossing with the optical axis 40 of a lens 34 and in parallel with the main scanning direction of the original A at a prescribed interval. In this case, the lens 34 collects the light from the picture information between positions b5 and-b6, between b3 and-b4 and between b1 and-b2 among the picture information on the main scanning line B of the original A to the CCDs 38a-38c. On the other hand, the CCDs 38d, 38e are arranged on a line in parallel with the CCDs 38a-38c in a focal plane of the lens 34 and the light from the original A is led to the CCDs 38d, 38e via the reflection mirror-36. The CCDs 38d, 38e receive the light from the picture information between positions b4 and-b5 and between b2 and-b3 among the picture information of the original A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device, and more particularly to an optical system including a plurality of photoelectric conversion elements and a total reflection mirror arranged in two rows along the main scanning direction of a scanned object. The present invention relates to an image reading device that is capable of reading image information carried on the object to be scanned over a wide range while maintaining high resolution through a combination of the following.

In recent years, in the fields of printing and prepress, streamlining of work processes,
2. Description of the Related Art Image scanning, recording and reproducing systems that electrically process image information carried on a document to create a film original are widely used for the purpose of improving image quality.

This image scanning, recording and reproducing system basically consists of an image reading device and an image reproducing device. That is, in the image reading device, a document that is sub-scanned and conveyed in an image reading section is main-scanned by a charging conversion element and converted into an electrical signal.

Next, the image information photoelectrically converted by the image reading device is subjected to arithmetic processing such as gradation correction and edge enhancement according to the plate-making conditions in an image reproducing device, and then converted to an optical signal such as a laser beam. Recording and reproduction are performed on a record carrier made of a photosensitive material such as film.

Note that this recording carrier is developed by a predetermined developing device and used for printing or the like as a film original plate or the like.

By the way, when the image reading device main scans a document and reads its image information, a CCD is used as a photoelectric conversion element.
(charge coupled device) is mainly used. Here, the CCD has a large number of electrodes that perform photoelectric conversion arranged in a line shape at high density, and the number of pixels of an easily available CCD is about several thousand at most. Therefore, one C
When image information of a document is read using a CD, its resolution becomes quite coarse. On the other hand, producing a dedicated COD with a larger number of electrodes arranged in order to improve resolution requires a large manufacturing cost and is not realistic.

Therefore, in order to obtain high resolution, image information is generally read using a plurality of CODs. For example, in FIG. 1, a document A carrying image information has image information between one end a and a central portion a2 transmitted through a lens 2 to a CCD 4.
Further, image information between the center portion a2 and the other end portion a3 is read by the CCD 8 via the lens 6. By combining the electric signals from each CCD 4 and 8, image information between al, a, and can be obtained with high resolution.

However, if the condition shown by the broken line A+ occurs due to uneven conveyance of the document A due to the conveyance system, curvature of the document A, or misalignment of the lens 2.6, the section ΔL near the central portion a2 will be affected by the CCD4. and 8, and therefore, image information in this section ΔL may be missing. On the other hand, manuscript A is broken line A! In this case, the image information of the section ΔM in the vicinity of the center a2 of the document A will be read by both the CCDs 4 and 8 redundantly.

As a result, when configured as shown in Figure 1, two CCDs
A portion of the image information read by steps 4 and 8 is missing or overlapped, and when the image information is reproduced by the image reproducing device, the image becomes unclear.

In order to solve this problem, there is a device in which the CCDs 4 and 8 are arranged as shown in FIG. 2 (see Japanese Patent Laid-Open No. 58-111568).

In this case, the CCDs 4 and 8 are arranged close to each other, and the angle θ2 between the principal ray 1σb of the CCD 4 and the principal ray 12b of the CCD 8, which read the image information near the central portion at of the original A, is the angle θ2 in FIG. Principal rays 10a, 12a
The angle θ is set to be smaller than the angle θ. Therefore, for example, when the document A is in the state indicated by the broken line A, the section ΔL' in which image information is missing near the center portion a2 is smaller than the missing section ΔL in FIG. Similarly, when the document A is in the state indicated by the broken line A2, the overlap area ΔM' of image information near the center a2 is also smaller than the overlap area ΔM in FIG.

As a result, even if the document A varies between the broken lines AI and A2, there is very little loss or duplication of image information read by the CCDs 4 and 8.

However, in the image reading device configured in this way,
As in the case described above, a plurality of lenses 2 and 6 are required depending on the number of CCDs 4 and 8 used, which not only makes it extremely troublesome to adjust the positions of the respective lenses 2 and 6, but also The lens 2 that requires precision
It has been pointed out that the production of 6 and 6 requires a large amount of time and cost.

On the other hand, there is another conventional technique constructed as shown in FIGS. 3a and 3b (see Japanese Patent Publication No. 57-46266). In this case, the image carried on document A? The light from the ff information is φ1 and φt (
After being reflected by two total reflection mirrors 14a and 14b set at an angle of φ1>φt), it passes through the lens 16 to the CCD 18a.

20a and the CCDs 18b and 20b. Snapshot, CCD18a, 20a and CCD18b, 20
b is in the main scanning direction (third direction) of the document, as shown in Figure 3.
The image information of the document A reflected by the total reflection mirror L4a is read by the CCDs 18a and 20a, and the total reflection mirror The image information of the original A reflected by 14b is read by CCDs 18b and 20b.

In the image reading device configured in this way, the CCD 18a
, 18b, 18b, 203 questions, and 20a120b can be made as close as possible or overlap each other,
Each CCD 18a, 18b, 2 due to fluctuations in document A, etc.
Missing or overlapping image information between 0a and 20b is minimized. Further, the lens 16 that focuses the light from the image information on each CCD 18a, 18b, 20a, and 20b may be provided, which facilitates position adjustment and reduces costs.

However, light from image information carried on document A is transmitted to predetermined CCDs 18a, 18b, 20a, 20b.
In order to make the light incident on each of the total reflection mirrors 14a and 1,
The angles φ8 and φ2 of 4b must be set accurately,
It has been pointed out that the adjustment work is complicated.

The present invention has been made to overcome the above-mentioned disadvantages, and includes a plurality of photoelectric conversion elements arranged alternately in two rows along the main scanning direction of a scanned object. A total reflection mirror having a reflective surface parallel to the main scanning direction is disposed between the object to be scanned, and the image information carried on the object to be scanned is transmitted through the optical system to the first mirror.
The image information is read by the photoelectric conversion elements in the row and read by the photoelectric conversion elements in the second row via the total reflection mirror and the optical system, thereby maintaining high resolution over a wide range without missing or duplicating the image information. I can do it,
Moreover, it is an object of the present invention to provide an image reading device with a simple configuration.

In order to achieve the above object, the present invention provides an image reading device that uses a photoelectric conversion element to main scan and read image information carried on a scanned object that is conveyed in the sub-scanning direction. a plurality of photoelectric conversion elements alternately arranged in two rows; an optical system that focuses light from the image information on each of the photoelectric conversion elements; and a reflection parallel to the main scanning direction. The total reflection mirror has a surface and directs light from a predetermined range of image information divided along the main scanning direction to a predetermined photoelectric conversion element and reflects it through the optical system. shall be.

Next, preferred embodiments of the image reading device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIGS. 4a and 4b, reference numeral 30 indicates the main body of the image reading device according to the present invention. This main body portion 30 includes a photoelectric conversion element group 32 that photoelectrically reads image information carried on the document A, and a lens 34 that is an optical system for condensing light from the image information onto the photoelectric conversion element group 32. and a total reflection mirror 36.

The photoelectric conversion element group 32 is composed of five CCDs 38a to 38e, among which CCDs 38a to 38
c are arranged at predetermined intervals on a straight line that intersects the optical axis 40 of the lens 34 and is parallel to the main scanning direction (arrow Y direction) of the original A, as shown in FIGS. 5 and 6. . In this case, the lens 34 scans the image information on the main scanning line B of the document A between b, , b6, b, , , in FIG.
The light from the image information between b4 questions and s, bt is captured by CCD
The light is focused on 38a to 3'8C, respectively.

On the other hand, the CCDs 38d and 38e are arranged in the focal plane of the lens 34 on a straight line parallel to the CCDs 38a to 38c at predetermined intervals and alternately with respect to the CCDs 38a to 38c. In this case, a total reflection mirror 36 having a reflective surface 36a that is perpendicular to the scanning surface of the original and parallel to the main scanning direction (arrow Y direction) is disposed between the lens 34 and the original A. be done. In addition, the total reflection mirror 36 reflects light from the image information between b4.53 and b2.53 among the image information on the main scanning line of the document A on its reflective surface 36a in FIG. lens 3
4 to the CCDs 38d and 38e. Here, it is suitable for reading image information if the light sources that illuminate the document A are disposed close to each other along the main scanning direction (arrow Y direction).

The image reading device according to the present invention is basically configured as described above, and its operation and effects will be explained next.

Therefore, the light from the image information of the image in the document A enters one end of the CCD 38C via the lens 34 along the principal ray 42a. Furthermore, light from the image information b2 enters the other end of the CCD 38C via the lens 34 along the chief ray 42b. Therefore, the image information between b, ,b, is C0D
38C (see Figure 4a). on the other hand,
The light from the image information in b is incident on the reflective surface 36a of the total reflection mirror 36 along the principal ray 44a, and then reflected and incident on one end of the CCD 38e via the lens 34. Further, the light from the image information of b is incident on the reflective surface 36a of the total reflection mirror 36 along the principal ray 44b, and then reflected and incident on the other end of the CCD 38e via the lens 34. Therefore, the image information between b, , and b is read by the C0D 38e (see Figure 4). Similarly, the light from the image information of b3 and b4 in original A is the principal light 'fa42
c, CCD 38b through lens 34 along 42d
Since the image information between b3 and b4 is incident on the CCD 38
read by b. Further, the light from the image information b4, b enters the reflective surface 36a of the total reflection mirror 36 along the chief rays 44c, 44d, and is reflected by the lens 3.
4, the image information between b4 and b is read by the CCD 38d. Furthermore, the light from the image information of b, , b6 is the chief ray 42e, 42
Since the light enters the CCD 38a through the lens 34 along the direction f, image information between b, , and b6 is read by the CCD 38a.

In this way, the image information between s and b6 on the main scanning line B of the original A is read by the CCDs 38a to 38e and converted into electrical signals. In this case, CCD3
The image information read by 8a to 38e is electrically processed into a predetermined array, and an image signal for one line along the main scanning direction (arrow Y direction) is formed. Note that since the document A is conveyed in the sub-scanning direction (arrow X direction) by a conveyance means (not shown), image information of the entire surface thereof is converted into an electrical signal.

Here, for example, the image information between question s, , b2 and s, , b in document A is in the main scanning direction (direction of arrow Y).
CCDs 38c and 38e arranged closely along
read by. Therefore, even if the document A is displaced in the direction of the arrow Z, loss of image information, duplication, etc. in the vicinity of b2 can be suppressed to a minimum. Also,
Since the CCDs 38a to 38e are arranged alternately, the intervals between adjacent CCDs 38a and 38b, between 38b and 38c, and between 38d and 386 can be set small. 38e, it becomes possible to perform a light condensing action with sufficiently high precision and without optical distortion. As a result, compared to the case where a plurality of optical systems are used, the position adjustment of the lens 34 is not only easier (but also has the advantage of reducing costs). In an aspect, bl
, b2, bl, b4, and the image information between
8c and between b, , b, and b4, b,
The image information between the
, 38e.

Therefore, it is only necessary to adjust the position of only one total reflection mirror 36 so that it is parallel to the main scanning direction.
As in the prior art shown in Fig. 3, two total reflection mirrors 1
CCD 18a, 18b, 20a at each position of 4a, 14b
, 20b, which not only simplifies the work, but also simplifies the configuration.

As described above, according to the present invention, a plurality of photoelectric conversion elements are arranged alternately in two rows along the main scanning direction of a scanned object, and image information carried on the scanned object is transmitted through an optical system. First
The light from the image information is read by the photoelectric conversion elements in the column, and is reflected by a total reflection mirror having a reflective surface parallel to the main scanning direction, and is converted into photoelectric data in the second column via the optical system. It is configured to be read by an element. Therefore, adjacent photoelectric conversion elements can be disposed close to each other, and omission or duplication of image information between the photoelectric conversion elements can be suppressed. Therefore, it is possible to maintain high resolution and reproduce accurate images. In addition, since the optical system can be used in common for each photoelectric conversion element and two rows of photoelectric conversion elements can be arranged with one total reflection mirror, the configuration can be reduced to N wheels and inexpensive. There is also an advantage that operations such as position adjustment of the optical system are extremely easy.

Although the present invention has been described above with reference to preferred embodiment B, the present invention is not limited to this embodiment.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory front view of an image reading device according to the prior art, FIG. 2 is an explanatory front view of an image reading device according to another prior art, and FIGS. 4a and 4b are perspective views of the structure of the image reading device according to the present invention; FIG. 5 is a plan view of the image reading device according to the present invention; FIG. 6 is an explanatory side view of the image reading device according to the present invention. 30... Main body 32... Photoelectric conversion element group 34... Lens 36... Total reflection mirror 38a to 38e--CCD A-original FIG,
1 FIG, 2 FIG, 5 FIG, 3b FIG, 4b

Claims (2)

[Claims] (1) In an image reading device that main-scans and reads image information carried on a scanned object that is conveyed in the sub-scanning direction, image information is arranged alternately in two rows along the main scanning direction of the scanned object using a photoelectric conversion element. a plurality of photoelectric conversion elements, an optical system that focuses light from the image information on each of the photoelectric conversion elements, and a reflective surface parallel to the main scanning direction, An image reading device comprising a total reflection mirror that directs light from a predetermined range of image information divided along a predetermined range along a predetermined range of image information to a predetermined photoelectric conversion element and reflects the light through the optical system. (2) In the device according to claim 1, the total reflection mirror is arranged so that its reflection surface is parallel to the main scanning direction and the optical axis of the optical system, and Light from the image information is focused on the element via the optical system, and light from the image information is focused on the second row of photoelectric conversion elements via the total reflection mirror and the optical system. An image reading device comprising: