Printing – Layout or registration
Reexamination Certificate
2001-03-15
2003-05-13
Hirshfeld, Andrew H. (Department: 2854)
Printing
Layout or registration
C101S463100, C101SDIG029
Reexamination Certificate
active
06561097
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet material positioning method and apparatus, in which sheet materials having a plurality of sizes are conveyed in a predetermined conveying direction so as to be loaded onto a surface plate, and the sheet materials are positioned at a predetermined position on the surface plate.
2. Description of the Related Art
A technique has been developed, in which a printing plate (hereinafter a photopolymer plate) in which a photosensitive layer (e.g., a photopolymer layer) is provided on a support is used, and in which an image is directly recorded on the photopolymer layer of the photopolymer plate by laser beams or the like. (This technique is used in an automatic exposure apparatus for printing plates.)
In this technique, an image is rapidly recorded onto a photopolymer plate, and thus, photopolymer plates need to be sequentially sent. Accordingly, it is preferable that a plurality of photopolymer plates are stacked in advance at a predetermined position and ready to be used, and that the photopolymer plates are automatically taken out one by one so as to be sent into an exposure section. After being sent into the exposure section, the photopolymer plates are preferably conveyed along a predetermined proper conveying path.
The photopolymer plate needs to be wound onto a printing drum at the time of printing, and in order to position the photopolymer plate on the printing drum, an automatic exposure apparatus for printing plates includes a process for forming a punch-hole in the photopolymer plate. The punching is carried out on a surface plate, which serves as a base for the exposure of the photopolymer plate, and is also for the sub-scanning movement. And the punch-hole serves as reference at the time of exposure.
Accordingly, the photopolymer plate delivered onto the surface plate must be positioned at a proper position.
In order to carry out the positioning, initially, an incline of the photopolymer plate is corrected, parallelism of the punch-hole of the photopolymer plate for a center line is corrected. Then, a direction of the photopolymer plate, in which the punch-hole is orthogonal to the center line, is determined based on inversion of output signals from a plurality of sensors (inversion from a photopolymer plate detected state to a photopolymer plate undetected state, or inversion from the undetected state to the detected state), which sensors are provided at positions, which are the corners of the photopolymer plate when the photopolymer plate is at the proper position. Namely, the incline of the photopolymer plate with respect to the center line of the surface plate on the surface plate is corrected, and the position of the photopolymer plate on the surface plate in a direction which is orthogonal to the center line is corrected by using the sensors.
However, the side of the photopolymer plate, which side is in the direction orthogonal to the center line, may have various sizes which are within a range from 400 mm to 745 mm in millimeter interval. Thus, if sensors are provided so as to be at the best position for the each of respective sizes of the photopolymer plates, an enormous number of sensors are required. Therefore, a predetermined number of sensors are disposed at predetermined positions within the above-described range (the predetermined number is a number which is fewer than the number of sizes of the photopolymer plates). The positioning of the photopolymer plate is carried out on the basis of a calculation result from detection results by the sensor. If the sensors are disposed at random positions in this way, the amount of movement for initially detecting a corner of the photopolymer plate by the sensor and the amount of movement obtained by the computations for positioning the photopolymer plate at the appropriate position vary depending upon the size of the photopolymer plate. As a result, there are disadvantages that, for example, the operation efficiency deteriorates, and the positioning accuracy varies depending upon the size of the photopolymer plate.
SUMMARY OF THE INVENTION
In consideration of the above facts, it is an object of the present invention to obtain a sheet material positioning method and apparatus, in which, positioning is carried out by a small number of sensors and at the time of positioning the sheet material, amount of movement for positioning can be minimized, and in which, improvement of the operation and stabilization of the positioning accuracy can be archived.
A first aspect of the present invention is a sheet material positioning method, in which, sheet materials having a plurality of sizes are conveyed in a predetermined conveying direction so as to be loaded onto a surface plate, and an incline and a position of the sheet material in a conveying direction of the sheet material with respect to a proper position are corrected, and the sheet material, whose incline and position with respect to the proper position have been corrected, is positioned at a predetermined position on the surface plate by being moved in a direction orthogonal to the conveying direction, by using a plurality of sensors for detecting at least one corner of the sheet material; and wherein at least one dimension of the sheet material in the direction orthogonal to the conveying direction has been recognized in advance; and wherein a sensor, which requires the smallest amount of movement of the sheet material for positioning the sheet material at the predetermined position, is selected from the plurality of sensors based on the recognized dimension of the sheet material, and the corner of the sheet material is detected by the selected sensor.
According to the first aspect of the present invention, with respect to the proper position, after the incline has been eliminated and the positioning in the conveying direction of the sheet material has been corrected, the sensor, which requires the smallest amount of movement of the sheet material for positioning, is selected based on the dimension of the sheet material. As a result, the time for positioning the sheet material can be shortened.
A second aspect of the present invention according to the first aspect is a sheet material positioning method, wherein, after the sheet material has been loaded onto the surface plate, a pressing member, which has a portion that is parallel to a side of the sheet material which side is orthogonal to the conveying direction, presses the sheet material to the proper position, so that the incline and the position in the conveying direction of the sheet material are corrected simultaneously.
According to the second aspect of the present invention, with respect to the proper position, the incline is eliminated and the positioning in the conveying direction of the sheet material is corrected in the following manner: After the sheet material has been loaded onto the surface plate, a pressing member, which has a line connecting at least two points, which line is parallel to a side of the sheet material which side is orthogonal to the conveying direction, is moved to the predetermined position, so that the incline and the positioning in the conveying direction of the sheet material are corrected simultaneously. In this way, the position of the side of the sheet material pressed by the pressing member is fixed, and thus, the sheet material can be easily positioned in the conveying direction thereof. However, since positioning of the sheet material in the direction which is orthogonal to the conveying direction on the basis of a center reference, if the size of the sheet material varies, the position of the sheet material in the direction which is orthogonal to the conveying direction respectively varies. As a result, the positioning method described in the first aspect is required, and the smaller the amount of movement of the sheet material for positioning, the shorter the time for positioning.
A third aspect of the present invention according to the first or second aspect is a sheet material p
Fuji Photo Film Co. , Ltd.
Ghatt Dave A.
Hirshfeld Andrew H.
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