JP3014474U - Document reader - Google Patents

Abstract

(57) [Summary] [Object] To provide a copying machine capable of detecting the position and size of a document having an arbitrary shape or color by obtaining a document reading device provided with a document position detecting means that does not require trimming processing. [Structure] A document reading device is provided with a backlight unit that irradiates light from the back side of the document during exposure scanning of the document, and detects the presence or absence of a shadow of the document caused by the irradiation light from the backlight unit as a difference in brightness. Detects the position, size and shape of a document. By making the backlight unit white, there is no pixel component, so that the trimming process is unnecessary.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a document reading device equipped with a document position detecting means used in a simple stencil plate making device or a copying machine.

[0002]

[Prior art]

 The original reading device used in simple stencil plate making machines and copiers places the original on a light-transmissive original table made of glass, etc., and presses the original with the original cover. There is one that performs a prescan from the bottom of the table before scanning the original. By this prescan, it is possible to detect the position and size of the document placed on the document table, select a paper of an appropriate size, set the magnification, and correct the document misalignment.

In order to easily determine the size of a document and automatically feed a standard size paper of an appropriate size, one point of the document table is set as the origin, and two points in the vertical and horizontal directions from the origin are set below the document table. There is also one in which an optical sensor is arranged according to the side length of a standard document. This is because the original table is blocked by the original, and the optical sensors arranged in two directions, vertical and horizontal, detect the non-transparent portions, and the original is applied to the standard size from the non-transparent portions and the transparent portions. It is used for automatic paper feeding and setting of magnification for copiers.

As an example of a document reading device capable of detecting the position and size of a document placed on such a document table, there are the devices described in JP-A-56-120264 and JP-A-3-172707. You can In the device of Japanese Patent Laid-Open No. 56-120264, the original cover is provided with a repetitive pattern of straight lines at an equal pitch at right angles to the scanning direction. When the document and the repeated pattern are read as image data, the position where the straight line forming the repeated pattern is interrupted by the document is detected. From the detected position, the lengths of the two sides of the rectangular original and the original position are obtained by calculation.

FIG. 3 and FIG. 4 are explanatory views showing an example of a conventional document reading apparatus, and show the apparatus of Japanese Patent Laid-Open No. 3-172707. As shown in FIG. 3, the apparatus of Japanese Patent Laid-Open No. 3-172707 provides an equal-pitch linear repeating pattern on the original cover 11 at 45 ° with respect to the scanning direction, so that the equal-pitch linear repeating pattern is provided in the scanning direction. The detection accuracy is improved as compared with the apparatus of Japanese Patent Laid-Open No. 56-120264, which is installed in a right angle.

In one example given here, the document 13 is placed on the basis of the center alignment position set on the document table 12, the document cover 11 is closed, and scanning is performed by the document reading device. The image data as shown in is obtained and temporarily stored in the memory. The image data on the memory is scanned in the direction shown by the arrow, and the original covers the original cover, and as shown by the black dots in the figure, the portion where the repeated pattern of straight lines with equal pitch is interrupted is detected. When three or more detection points are lined up on a straight line, it is possible to detect the position and size of a document outside the standard size by recognizing it as the side of the document.

Further, since most of white or light color originals are used, a black pressure plate is used for the original cover to read the original and the original cover as image data, and the difference between the brightness data of the white or light color original and the black pressure plate is read. There is also one that detects the position and size of the document from the. By using the document reading device that can detect the position and size of the document as described above in a copier, etc., it can be used for automatic correction of document misalignment and automatic selection of printing paper for standard and non-standard size documents. are doing.

[0008]

[Problems to be solved by the device]

 In this way, the original reading device that can detect the position and size of the original does not require accurate alignment when placing the original on the original table, and it is possible to automatically select the printing paper. ing.

However, in the case of detecting the position and size of a document from the difference in brightness from a white document by using a black pressure plate on the document cover, the detection is not accurate when, for example, a document provided with a black edge is used. On the other hand, in the case where the document cover is provided with straight-line repeating patterns of equal pitch, the position and size of the document are calculated by detecting the portion where the straight line forming the repeating pattern is interrupted by the document. Since it is difficult to grasp the exact shape of the whole manuscript, it is not possible to use a manuscript of any shape and it is limited to a square manuscript.

[0010] Because the original cover that is the background of the original at the time of scanning is read, the read image data is used for printing and the like, whether the original cover uses a black pressure plate, the one in which a straight line repeating pattern with an equal pitch is provided In that case, it is necessary to perform trimming processing to erase the black plate and the repeated pattern part of the document cover, which is the background other than the document.

The trimming process for a square original is easy, but the trimming process for an irregular original is difficult. Therefore, for an original of any shape, the trimming process can be performed even if the position and size can be known. There are cases where it cannot be done. For this reason, the detection of the position and size of the document in the conventional document reading apparatus is intended only for the rectangular document and the white document.

The present invention provides a copier capable of detecting the position and size of a document having an arbitrary shape or color by obtaining a document reading device including a document position detecting unit that does not require trimming processing. To aim.

[0013]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, in the present invention, a document reading device having a prescan function is provided with a backlight unit that irradiates light from the back side of the document during prescanning of the document. The presence / absence of a shadow of an original generated by light is detected as a difference in brightness and darkness, and the position, size and shape of the original are detected.

A document reading apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view illustrating the outline of the structure of the document reading apparatus of the present invention. A document 3 is placed on the document table 2 with the reading surface facing down. The backlight unit 1 is provided so that the light emitting surface covers the back side of the document 3 placed on the document table 2.

FIG. 2 is a sectional view for explaining the document position detecting means of the document reading device of the present invention. When the backlight unit 1 irradiates the light, the portion blocked by the original 3 placed on the original table 2 forms a dark portion due to the shadow 5 of the original 3, and the portion illuminated by the light from the backlight unit 1 is bright. To form a part.

As shown by the arrow in the drawing, scanning is performed by the scanner 4 so that the portion of the shadow 5 formed by the original 3 placed on the original table 2 and the portion irradiated with the light from the backlight unit 1 are read. By determining the read image data and detecting lightness and darkness, the portion of the original 3 can be recognized and the size, position, and shape of the original can be obtained. Further, by making the back light unit 1 white, the trimming process becomes unnecessary.

The document reading device of the present invention is capable of grasping the size, position, and shape of a document as long as it is a document that can be shaded by the light emitted from the backlight unit. Can be used. Since the trimming process is unnecessary, the shape of the target document does not matter.

As the backlight unit used in the device of the present invention, one using electroluminescence, one combining a fluorescent tube and a light diffusion plate, or the like is used. In addition to this, an appropriate light emitting body can be used as the backlight unit.

[0019]

[Effect of device]

 As described above, the document reading apparatus of the present invention is provided with a backlight unit that irradiates light from the back side of the document, and detects the presence or absence of a shadow of the document caused by the irradiation light from the backlight unit as a difference between light and dark, and Got position, size and shape. Therefore, the position, size, and shape of the original can be obtained regardless of the background color of the original if the original has a shadow by the irradiation light.

It is possible to accurately detect the position, size, etc. of a color original or an original with a black border. If the backlight unit is made white, the trimming process is unnecessary, and therefore the original position, size, and shape can be obtained for originals of any shape, not limited to square originals. By equipping a copying machine with the document reading device of the present invention, it is possible to read a document at an arbitrary position on the document table, and it is easy to copy an irregular document.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating the outline of the structure of a document reading apparatus of the present invention.

FIG. 2 is a sectional view illustrating a document position detecting unit of the document reading device of the present invention.

FIG. 3 is an explanatory diagram showing an example of a conventional document reading apparatus.

FIG. 4 is an explanatory diagram showing an example of a conventional document reading apparatus.

[Explanation of symbols]

 1 Backlight Unit 2 Original Table 3 Original 4 Scanner 5 Shadow 11 Original Cover 12 Original Table 13 Original

Claims (2)

[Scope of utility model registration request] 1. A document reading apparatus having a prescan function, wherein means for applying light from the back side of the document at the time of prescanning the document, and light and dark produced by light emitted from the back side of the document by the means for applying the light. An original reading device comprising an original position detecting means for determining the position, size and shape of an original by determining the. 2. In an original reading apparatus having a prescan function, means for applying light by electroluminescence from the back side of the original during prescanning of the original, and light emitted from the back side of the original by the means for applying the light. An original reading device comprising an original position detecting means for detecting the position, size and shape of an original by discriminating the lightness and darkness caused by.