Claims
- 1. A method of registering a position of an image region on an image surface of a printing plate with respect to a plate cylinder in an offset printing machine in which said printing plate is automatically fed to said plate cylinder and is clamped at an end portion of the printing plate adjacent to said image region onto said plate cylinder by a clamping device which is swingable relative to a base side line of said plate cylinder, said method comprising the steps of:
- drawing a first line, on the image surface at said end portion, which is in parallel with an outline of said image region adjacent to said end portion;
- drawing a second line, on the image surface at said end portion, which is perpendicular to said first line and passes through a center of said image region;
- detecting positions of said first and second lines and opposite lateral edges of said printing plate;
- calculating an amount of displacement of the position of said image region relative to a standard position in rotational, lateral and twist directions of said plate cylinder, on the basis of a relationship between the detected positions of said first and second lines and said lateral edges; and
- adjusting the position of said image region in the twist direction by swinging said clamping device relative to the base side line of said plate cylinder in correspondence with the calculated amount of displacement in the twist direction.
- 2. A method according to claim 1, further comprising the step of adjusting the position of said image region in the rotational direction by rotating the plate cylinder in correspondence with the calculated amount of displacement in the rotational direction.
- 3. A method according to claim 1, further comprising the step of adjusting the position of said image region in the lateral direction by moving said plate cylinder in the lateral direction in correspondence with the calculated amount of displacement in the lateral direction.
- 4. A method according to claim 1, wherein before the step of drawing said first line, an original is printed onto said image surface, and said first line is drawn in parallel with an outline of one side of said original at said end portion.
- 5. A method according to claim 1, wherein, in the calculating step, the amount of displacement in the rotational direction is determined as a predetermined function of a distance between an edge of said printing plate at said end portion and a first point on said first line and a distance between said edge and a second point on said first line, which is separated from said first position by a predetermined distance.
- 6. A method according to claim 1, wherein, in the calculating step, the amount of displacement in the lateral direction is determined as a predetermined function of a width of said printing plate and a distance between a lateral edge thereof and a predetermined point on said second line.
- 7. A method according to claim 1, wherein, in the calculating step, the amount of displacement in the twist direction is determined as a predetermined function of a distance between an edge of said printing plate at said end portion and a first point on said first line, a distance between said edge of said printing plate and a second point on said first line, which is separated from said first point by a predetermined distance, a width of said printing plate and a distance between said first and second points.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2-417184 |
Dec 1990 |
JPX |
|
3-144929 |
Jun 1991 |
JPX |
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Parent Case Info
This is a division of copending application Ser. No. 07/817,791, filed on Dec. 27, 1991, now U.S. Pat. No. 5,167,186.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
817791 |
Dec 1991 |
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