JPS642312B2 - - Google Patents

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 one-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 an original moved by a moving device (not shown), and 4 is a fluorescent lamp.

In such a document reading device, a fluorescent lamp 4 is used.
The light emitted from the image sensor 1a and reflected from the part of the reading line 5 on the original 3 toward the image sensor 1a forms an image on the light receiving part of the image sensor 1a by the lens 2a, while the light emitted from the fluorescent lamp 4 , one line is read by imaging the light reflected from the portion of the reading line 5 toward the image sensor 1b by the lens 2b on the light receiving section of the image sensor 1b.

However, in such conventional document reading devices, when the document 3 is not at the normal reading position, the image sensors 1a and 1b may read the same portion of the document 3 overlappingly, or conversely, a certain portion of the document may be read by the image sensors 1a and 1b. Both the image sensors 1a and 1b had a drawback that they could not be read.

FIGS. 2 and 3 show such a state (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 difference between the part read by the image sensor 1a and the part read by the image sensor 1b. There are no overlapping or missing parts in between. However, manuscript 3
When the reading position becomes position B, which is farther from the image sensors 1a, 1b than the normal reading position A within the depth of field of the lenses 2a, 2b, the image sensor 1a moves between points B ₁ - B ₄ to the image sensor 1b. reads between points B ₃ and B ₆ respectively. Therefore, the output of the reading device in this case is B in Figure 3.
The area between points B ₃ and B ₄ (b ₂ ) is output twice, and the area between points B ₁ and B ₂ (b ₁ ) outside the width of document 3 and between points B ₅ and B ₆ ( _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 L of the original 3.

On the other hand, in FIG. 2, when the reading position of the original 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 is turned off.
The image sensor 1b reads between C ₂ and C ₃ , between points C ₄ and C ₅ , and between points C ₁ and C ₂ (c ₁ ), and between points C _{3 and C 3} .
The area between C ₄ (c ₂ ) and between points C ₅ and C ₆ (c ₃ ) is not read by either of the image sensors 1a and 1b. Therefore, in this case, as shown in C in FIG. 3, a phenomenon occurs in which the reading device does not output c ₁ , c ₂ and c ₃ .

Such drawbacks also exist in document reading devices that use a stationary document type. FIG. 4 shows a conventional document reading device of a stationary document type. Reference numeral 6 denotes a document table made of a transparent glass plate, and a document 13 is placed on this document table 6.
By placing the document 13, the document 13 is read in a stationary state. 1a and 1b are image sensors, and 2a and 2b are lenses.

In the case of such a stationary document type, if the upper surface of the document table 6 is set as the normal reading position A as shown in the figure, the document 3 cannot take the position C, and a situation where information is missing is prevented. However, as shown in the figure, when a book or the like is used as the original 13, a part of the original 13 often takes position B, and there is a drawback that an output like B in FIG. 3 is frequently generated.

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 not being read by any of the image sensors. 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.

FIGS. 5 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 document 3 and the screen 7 .
Regarding the screen 7, one-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 are arranged on the same straight line extending in the main scanning direction. are arranged in Sensor imaging lenses 9a and 9b are provided between the screen 7 and the image sensors 1a and 1b. In addition, the 6th
In the figure, the arrow indicates the main scanning direction.

In the document reading device configured in this manner, light emitted from the light source and reflected at the reading line 5 on the document 3 is transmitted to the screen imaging lens 8.
The light imaged on the screen 7 is further transmitted through the screen 7, and is imaged on the light receiving parts of the image sensors 1a and 1b by the sensor imaging lenses 9a and 9b. As a result, the original 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 original 3 will not form an image on the screen 7 (please note that the screen 7 is ).

In addition, in this device, the image sensors 1a, 1b
It is also easy to determine the position of the screen 7 with respect to the sensor imaging lenses 9a and 9b.
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 will be Both image sensors 1
It is possible to prevent images from being formed on the light receiving sections of the image sensors 1a and 1b, or from light emitted from a certain part of the image of the original 3 on the screen 7 not forming an image on any of the light receiving sections of the image sensors 1a and 1b. .

As a result, the same portion of the document 3 will not be read by both image sensors 1a, 1b, or a portion of the document 3 will not be read by either of the image sensors 1a, 1b.

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

1a and 1b are image sensors arranged on the same straight line parallel to the document table 6 and extending in the main scanning direction; 9a and 9b are sensors for imaging provided between the screen 7 and the image sensors 1a and 1b; It's a lens.

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 original 13 is read by the image sensors 1a, 1b by forming images of the light onto the light receiving portions of the image sensors 1a, 1b by the sensor imaging lenses 9a, 9b.

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 to position D, etc. As a result, the sharpness of the image corresponding to the raised portion of the document 13 on the screen 7 decreases. Therefore, the sharpness of the corresponding portions of the images on the image sensors 1a, 1b will also be reduced, but as long as the position of the screen 7 is properly adjusted, the same portion of the document 13 will be visible on both image sensors 1a, 1b. will not be read twice.

In the above embodiment, the light reflected by the original is imaged on the screen, but the light transmitted through the original may be switched to the screen.

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.

Furthermore, in the above embodiment, two image sensors are used.
Although only one image sensor is used, it goes without saying that the present invention can also be applied to a document reading device that uses an even 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 this screen into multiple systems of optical systems. By forming images on multiple image sensors using the sensor imaging optical system, it is possible to avoid the possibility that the same part of the document will be read twice by adjacent image sensors, or that a part of the document will not be read by any of the image sensors. This provides an excellent effect of preventing image deterioration at the connections between the image sensors. Furthermore, since the image is once formed on the screen, a plurality of image sensors can be installed in a straight line, and the entire device can be made smaller.

[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 configuration diagram of the conventional device viewed from a direction perpendicular to the optical axis, and FIG. 3 is a perspective view of a conventional document moving type document reading device. 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. FIG. 5 is a diagram showing a document according to an embodiment of the present invention. A perspective view of a reading device;
FIG. 6 is a schematic configuration diagram of the embodiment as viewed from a direction perpendicular to the optical axis, and FIG. 7 is a schematic configuration diagram of another embodiment of the present invention viewed from a direction perpendicular to the optical axis. 1a, 1b... one-dimensional image sensor, 3...
Original, 7...screen, 8...imaging lens,
9a, 9b...Sensor imaging lens, 13...Document.

Claims (1)

[Claims] 1. A document illuminating means for illuminating a document, a translucent screen installed parallel to the main scanning direction of the document, and a translucent screen provided between the document and the screen, and a light source provided on the screen by the document illuminating means. one first lens that forms an image of the light coming from the original document, a plurality of image sensors arranged in a straight line parallel to the main scanning direction of the original document, and the image sensor and the screen. a plurality of second lenses, which are provided in one-to-one correspondence with each of the image sensors in between, and which form an image of light coming from the screen onto a light receiving section of the corresponding image sensor; Device.