JPS5850859A - Original reader - Google Patents

Abstract

PURPOSE:To prevent a picture from deteriorating at connection points between image sensors by focusing an image, arriving from a screen, on plural image sensors through plural optical systems for sensor image formation. CONSTITUTION:Light emitted from a light source and reflected at a readout line 5 on an original is passed through a lens 8 for screen image formation to form an image on a screen 7, and the light is further transmitted through the screen 7 to form an image on photodetection parts of image sensors 1a and 1b through lenses 9a and 9b for sensor image formation, thus reading the original 3 by the image sensors 1a and 1b. Light reflected by the original 3 is passed through the lens 8 for screen image formation as one system to form the image on the screen, so even if the original 3 shifts in readout position, light reflected at the same part on the original never forms overlapping images at different parts on the screen 7, and light reflected at some part on the original 3 fails in image formation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document reading device that reads a document using a plurality of image sensors.

Since there is a limit to the number of pixels that can be provided on one image sensor, the document reading device uses a plurality of image sensors to read the document if necessary.

FIG. 1 shows a document moving type document reading device using two -dimensional image sensors among conventional document reading devices of this type. 1a and 1b are image sensors arranged on the same straight line; 2a and 2b are lenses; 3 is a document moved by a moving device (not shown); and 4 is a fluorescent lamp.

In such an original reading device, light is emitted from the fluorescent lamp 4, and the image sensor 1a of the reading line 6 on the original a is emitted from the fluorescent lamp 4.
The light reflected in the portion toward the image sensor 1a is imaged by the lens 2a on the light receiving portion of the image sensor 1a, while the light emitted from the fluorescent lamp 4 is reflected in the portion of the reading line 6 toward the image sensor 1b side. light is lens 2b
One line is read by forming an image on the light receiving section of the image sensor 1b.

However, in such a conventional document reading device, when the document 3 is not at the normal reading position, the image sensor 1
There is a drawback that the same portion of the document 3 may be read overlappingly on the image sensors 1a and 1b, or a certain portion of the document may not be read by either the image sensors 1a or 1b.

FIG. 2 and FIG. 3 show such a state (note that the arrow S in FIG. 2 indicates the main scanning direction). In FIG. 2, when the document 3 is at the normal reading position indicated by position A (usually this position is considered to be the best focus), there is a gap between the part read by the image sensor 1a and the part read by the image sensor 1b. To,
There are no duplicates or missing parts. However, when the reading position of the original 3 is within the depth of field of the lenses 2a and 2b, the reading position of the image sensors 1a and 1b is lower than the normal reading position A.
When the image sensor 1a reaches position B, which is far away from the point
Read between each. Therefore, the output of the reading device in this case will be as shown in Figure 3, B'', and the output will be at point B5-
114 (b2) is output twice, and the points B1-B2 (b, ) and the points B6-B on the outside of the width of the document 3 are output twice.
6 interval (b3) is also output.

Further, as a result, the image information of the original 3 is output after being reduced in size than the actual width of the original 3.

On the other hand, in FIG. 2, when the reading position of the document 3 is at position C, which is closer to the image sensors 1a and 1b than the normal reading position A, the image sensor 1a moves between points C2 and C, and the image sensor 1b moves between points C4 and 1b. The points between C5 and C5 are read respectively, and the points between C1 and C2 (C1), between C3 and C (Co) and between C6 and C (C3) are not read by either of the image sensors 1a and 1b. . Therefore, in this case, a phenomenon occurs in which the above-mentioned 0, +02 and C are not output from the reading device, as shown in C in FIG.

Such drawbacks also exist in document reading devices that use a stationary document type. FIG. 4 shows a conventional document table with a stationary document, and by placing the document 13 on this document table 6, the document 13 is read in a stationary state.・1°:1
2a and 2b are lenses.

In the case of such a stationary original type, the original platen 6 is used as shown in the figure.
If the upper surface of ' is the normal reading position A, then the document 3 is at position C.
This will prevent situations in which information is missing due to unavailability. However, as shown in the figure, when a book or the like is used as the manuscript 13, a part of the manuscript 13 often takes the position B, and the third
There was a drawback that output like B in the figure frequently occurred. .

The present invention has been made to solve the above-mentioned conventional drawbacks, such as the same part of a document being read redundantly by multiple image sensors, or a part of the document being not read by any image sensor. The purpose of the present invention is to provide a document reading device that does not cause problems.

The present invention will be described below based on embodiments shown in the drawings.

6 and 6 show an embodiment of the original moving type. Reference numeral 3 denotes a document, which is moved in the sub-scanning direction by a document moving device (not shown). 4 is a fluorescent lamp that illuminates the original 3, and 7 is a translucent screen installed parallel to the original 3.

A system of screen imaging lenses 8 is provided between the original 3 and the screen 6.

Regarding the screen 7, -dimensional image sensors 1a and '1b are provided on the opposite side of the original 3 and the screen imaging lens 8, and these sensors 1a and 1b extend in the main scanning direction. arranged on the same straight line. The screen 7 and the image sensors 1a and 1b
Sensor imaging lenses 9a and 9b are provided between the two. Note that in FIG. 6, the arrow indicates the main scanning direction.

In the document reading device configured in this way, the light emitted from the light source and reflected at the reading line 6 on the document 3 is imaged on the screen 7 by the screen imaging lens 8, and the screen 7 The light imaged on the screen 7 passes through the screen 7, and the sensor imaging lenses ga and sb
By forming an image on the light receiving portions of the image sensors 1a and 1b, the original document 3 is read by the image sensors 1a and 1b.

Here, the light reflected by the original 3 is imaged on the screen 7 by one system of screen imaging lenses 8, so even if the reading position of the original 3 is shifted, the light reflected from the same part of the original 3 is not reflected. The light reflected from a certain part of the document 3 will not form an image on the screen 7 (note that the screen 7 is not sufficiently large). ).

Furthermore, in this device, it is easy to determine the position of the screen 7 with respect to the image sensors 1a, 1b and the sensor imaging lenses 9a, gl).

Therefore, if the position of the screen 7 is adjusted to correspond to the position A of the original 3 in FIG. 2, the light emitted from the same part of the image of the original 3 on the screen 7 can be Image sensor 1a.

1b, or light emitted from a certain part of the image of the original 3 on the screen 7 is transmitted to the image sensor 1a, 1b.
It is possible to prevent the image from not being formed even on the light receiving portion which is shifted by b.

As a result, the same part of the document 3 is displayed on both image sensors 1.
This eliminates the possibility that one reading is missed by either of the image sensors 1a or 1b, or a part of the document 3 is not read by either of the image sensors 1a or 11).

FIG. 7 shows an embodiment in which the present invention is applied to a document reading device of a stationary document type. 6 is a manuscript table made of a transparent glass plate, 7
8 is a screen provided parallel to the document table 6, and 8 is a screen imaging lens provided between the document table 6 and the screen 7.

,..., b- are image sensors, sa, 9 arranged on the same straight line parallel to the original document assembly and extending in the main scanning direction.
b is a Senna imaging lens provided between the screen 7 and the image sensors 1a and 1b.

In this embodiment, as in the previous embodiment, the light reflected by the original 13 placed on the original platen 6 is imaged on the screen 7 by the screen imaging lens 8, and is further transmitted through this screen. The light is transmitted to the sensor imaging lenses 9a, 9.
By forming an image on the light receiving parts of the image sensors 1a and 1b by the image sensor b, the original 13 is focused on the image sensors 1a and 1b.
will be read more.

Therefore, the same effects as in the embodiment described above can be obtained. That is, if the surface of the document table 6 is the best focus position of the screen imaging lens 8, and a part of the document 13 such as a book is lifted from the top surface of the document table 6, the screen 7 The sharpness of the image corresponding to the raised portion of the upper document 13 is reduced. Therefore, the corresponding parts of the images on the image sensors 1a, 1b will also have reduced sharpness, but as long as the position of the screen 7 is properly adjusted, the same part of the original 1a will overlap on both image sensors 1a, 1b. It will not be read as such.

In the above embodiment, the light reflected by the original is imaged on the screen, but the light transmitted through the original may be imaged on the screen. Furthermore, in the above embodiment, the screen is translucent and the light transmitted through the screen is imaged on the image sensor, but the screen is of a reflective type and the light reflected on the screen is imaged on the image sensor. You can also do this.

Further, in the embodiments described above, a lens is used as an image forming means, but an image forming means other than a lens may be used.

1. Furthermore, in the embodiment described above, only two image sensors are used, but it goes without saying that the present invention can also be applied to a document reading device that uses a larger number of image sensors.

As is clear from the above description, the document reading device according to the present invention forms an image of the light coming from the document on the screen using one system of screen imaging optical system, and further focuses the light coming from the screen into multiple systems. By forming an image on multiple image sensors using the sensor imaging optical system of the sensor, it is possible to prevent the same part of the document from being read twice by adjacent image sensors, or part of the document from being read by all the image sensors. This provides an excellent effect of preventing image deterioration at the connections between the image sensors.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional document moving type document reading device, FIG. 2 is a schematic diagram of the conventional device viewed from a direction perpendicular to the optical axis, and FIG. 3 is a change in the document reading position. According to the above,
An explanatory diagram showing changes in the output of a conventional device; FIG. 4 is a schematic configuration diagram of a conventional stationary document reading device viewed from a direction perpendicular to the optical axis; and FIG. 6 is a diagram showing the present invention and one embodiment. FIG. 6 is a schematic configuration diagram of the embodiment as seen from a direction perpendicular to the optical axis, and FIG. 7 is a perspective view of another embodiment of the present invention as seen from a direction perpendicular to the optical axis. It is a schematic block diagram. 1a, 1b...-dimensional image sensor, 3...
...Manuscript, 7...Screen, 8...
- Imaging lens, sa, eb...Sensor imaging lens, 13...Original. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A plurality of image sensors, a screen, one system of screen imaging optical system for forming an image of a document on the screen, and a plurality of image sensors are provided in one-to-one correspondence with each of the image sensors, The image sensor receives the corresponding light.