JPS6363147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device that linearly reads an image of a document using two one-dimensional image sensors.

When reading wide documents or documents with high reading resolution using an image reading device such as a facsimile that uses a one-dimensional image sensor, for example, when reading a B4 width document (effective reading width 256 mm) at a resolution of 16 lines/mm. , 4096 elements are required as the number of detection pixels of a one-dimensional image sensor. However, when a one-dimensional image sensor with 4096 elements is currently manufactured, many defects occur due to the large number of detection pixels, resulting in an expensive product that does not match the performance and cost. For this reason, conventional devices of this type have used two one-dimensional image sensors with a detection pixel count of 2048, which are relatively inexpensive to manufacture.

As shown in FIG. 1, the configuration is such that a document 2 is conveyed by a platen roller 1, and an image of the document 2 is formed on two one-dimensional image sensors 4a and 4b by two lenses 3a and 3b, respectively. It is to be read with With this configuration, as shown in FIG. 1, when the original 2 floats above the platen 1, the image range _l1 at the center of the original 2 cannot be read by the two one-dimensional image sensors 4a and 4b. Therefore, in this case, when the image of the document 2 is read by the two one-dimensional image sensors 4a and 4b and the read image is recorded, the image is omitted at the center of the recorded image. Furthermore, in this configuration, the optical system is fixed and the object to be read is movable, and in the case of books, it is very difficult to transport them.

Therefore, as a solution for reading three-dimensional images such as books, an image of a book 6 placed on a platen glass 5 is converted into a one-dimensional image using two lenses 3a and 3b, as shown in FIG. sensor 4a,
4b, for example, fixing the document table glass 5 on the side of the book 6, and moving the one-dimensional image sensors 4a, 4b in a direction perpendicular to the reading direction of the one-dimensional image sensors 4a, 4b. Conceivable. In this configuration, the optical paths read by the two one-dimensional image sensors 4a and 4b intersect at the center A of the image. Therefore, when the binding part B of the book 6 is located at the center part A, the two one-dimensional image sensors 4a and 4b perform overlapping reading of images in the image range _l2 shown in FIG. The same holds true when the document floats up.

The present invention provides an image reading device that uses two one-dimensional image sensors, even if the original is floating from the reference reading position or the book has a binding section.
It is an object of the present invention to provide an image reading device that does not cause duplicate reading of those images. An embodiment of the present invention will be described below based on the drawings.

FIGS. 4 and 5 are configuration diagrams of essential parts of the present invention, respectively. In FIGS. 4 and 5, reference numeral 5 denotes an original platen glass, and the original 2 and books 6 are placed on the original platen glass 5. As shown in FIG. 7 is a reflecting mirror having a V-shaped cross section and having two reflected images. The reflecting mirror 7 is used to hold the manuscript 2 or the book 6.
An arbitrary point 0 on the perpendicular line X passing through the center of the image is set as a base point, and the images are arranged symmetrically with respect to the perpendicular line X from the base point 0. Further, the reflective surface P faces the image, and the angle θ formed with the perpendicular line X is an obtuse angle. Reference numerals 4a and 4b are one-dimensional image sensors that perform line scanning on the image in the main scanning direction and read the image. Lenses 3a' and 3b' form the images on one-dimensional image sensors 4a and 4b. Note that the reflective surface P is at an obtuse angle θ
By doing so, the lenses 3 are arranged so that the optical axes C of the two lenses 3a and 3b via the reflecting mirror 7 are approximately parallel to the perpendicular line X and located near the perpendicular line X.
I was able to place a' and 3b'.

FIG. 4 shows a one-dimensional image in which the lenses 3a' and 3b' are arranged so that the optical axes C of the two lenses 3a' and 3b' via the reflecting mirror 7 pass approximately on the perpendicular line X. The first bit of each of the sensors 4a and 4b is arranged on the optical axis. Therefore, when the image of the floating original 2 is read by the two one-dimensional image sensors 4a and 4b, the images do not intersect at the center A as in the conventional case. Therefore, there is no possibility that the image of the original 2 will be read partially overlappingly. However, with this configuration, if the edge precision of the base point 0 of the reflecting mirror 7 or the flatness near the edge is poor, the reflection angle of the reflected light of the image will change and the one-dimensional image sensor 4
Due to variations in the amount of light received by a and 4b, it may not be possible to read the image in the central portion A. FIG. 5 shows an embodiment that improves this point.

In the configuration shown in FIG. 5, only the lenses 3a', 3b' and the one-dimensional image sensors 4a, 4b are used so that the central part A of the image is reflected on the reflective surface with good flatness near the edge of the reflecting mirror 7. As shown in FIG. 5, it is characterized by being slightly spaced downward from the document table glass 5 in FIG. Therefore, the optical axis C of the two lenses 3a' and 3b' via the reflecting mirror 7 is almost parallel to the perpendicular line X and passes near the center part A of the image, so that the two one-dimensional Image sensor 4a, 4b
The optical paths of the first bits of each intersect at an angle of Δα° in the center of the image. Therefore, the image of the book 6 near the binding section is captured by the two one-dimensional image sensors 4.
When reading with a and 4b, the image range of _l3 is read overlappingly. However, the two lenses 3
By locating the optical axes of a' and 3b' near the edge of the reflecting mirror 7, the angle at which the optical paths intersect (Δα°)
is much smaller than in the past, and duplicate reading of images is not a problem in practice. Note that even if the original 2 floats, a similar effect can be obtained.

In the embodiments shown in FIGS. 4 and 5, when reading the entire image, for example, the document glass 5 on the side of the document 2 and the book 6 is fixed, and the mirror 7, lenses 3a', 3b', one-dimensional image sensor 4a, 4b is moved in a direction perpendicular to the main scanning direction of the one-dimensional image sensors 4a and 4b to perform reading.

In addition, since an image sensor generally reduces and reads a linear image of a document, the relationship between the distance L _A between the document and the lens and the distance L _B between the lens and the image sensor is as follows. Although L _A ≫ L _B ,
In the present invention, reflected light can be incident on the lens without increasing the distance between the original and the total reflection mirror, so the apparatus can be sufficiently miniaturized.

Furthermore, in the present invention, L _A which is sufficiently larger than L _B
Since the total reflection mirror is placed at the position, the size of the total reflection mirror is not limited, and the mirror position can be adjusted very easily at this position.

As is clear from the above examples, the present invention
Two reflecting mirrors that divide the reflected light of the image into two for one main scan are placed at positions facing the images of manuscripts, books, etc., and lenses and one-dimensional mirrors are placed at positions corresponding to each of the two reflecting mirrors. By installing an image sensor and a lens between the image sensor and the total reflection mirror, it is possible to eliminate partial redundant reading of images, even in the case of floating manuscripts or bound parts of books. Highly accurate reading can be achieved using two highly reliable and inexpensive image sensors that do not cause a decrease or variation in the light intensity of the sensor, and the device is compact and the mirror adjustment is very easy. Excellent image reading. It provides equipment.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of main parts showing an example of a conventional image reading device, FIG. 2 is a perspective view of main parts showing another example of the conventional structure, FIG. 3 is a front view of main parts of FIG. The figure is a block diagram of main parts showing one embodiment of the present invention, and FIG. 5 is a block diagram of main parts showing another embodiment. 3a', 3b'... Lens, 4a, 4b... One-dimensional image sensor, 7... Mirror.

Claims (1)

[Claims] 1. In an image reading device that reads an image of a document linearly and divided into two for one main scan using two one-dimensional image sensors, an image reading device is installed near a perpendicular line passing through the center of one main scanning width, and the image is divided into two for one main scan. two total reflection mirrors that reflect each of the reflected lights of the linear image, a pair of one-dimensional image sensors that receive the light reflected by the total reflection mirror, and each of the lights reflected by the total reflection mirror. a lens provided between the total reflection mirror and the one-dimensional image sensor for forming reflected light of a linear image on the one-dimensional image sensor; An image reading device characterized in that the two lenses are arranged so that optical axes of the two lenses are substantially parallel to the perpendicular line and pass near the center of the one main scanning width.