Apparatus for producing a seamless copy from an unjointed original
AssigneeZed Instruments Limited
InventorsPeter M. Zollman, Keith G. Doyle
Life of this patent
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Abstract
A copying system has an artwork carrier cylinder and a printing cylinder, and electronic control means "stretches" the copy to exactly 360.degree. on the printing cylinder, to produce matched endless joints. The circumferential length of the original is first determined and then the original is scanned by a "read" scanner, the output of which is digitized and temporarily stored in memory. The contents of the memory are used to modulate a power laser during scanning to "write" on the printing cylinder but readout from the memory is adjusted in accordance with the circumferential length determined to produce the required jointing. The system may be varied to produce flexographic rollers, gravure cylinders or general copying.
Claims17
Copying apparatus for producing a seamless copy from an unjointed original having leading and trailing edges separated by a gap, said apparatus comprising:
- a first rotary carrier for carrying an original and a second rotary carrier including a copy surface;
- a "read" scanning means movable relative to the first carrier for scanning the original on the first carrier;
- a laser;
- means for passing the information from the "read" scan to said laser to modulate the output of the laser;
- means for causing relative movement between the modulated laser output and the second carrier so as to perform a "write" scan to transfer a pattern derived from the "read" pattern to the copy surface;
- said means for passing information including a store for storing data obtained in scanning the original;
- means for measuring the circumferential length of the original when on the first carrier;
- and store-controlling means connected to the output of the measuring means and effective to control the store in accordance with the measuring means output to ensure that each scan of the second carrier is filled by data from the original outside the gap.
Copying apparatus for producing a seamless copy from an unjointed original having leading and trailing edges separated by a gap, said apparatus comprising:
- a first rotary carrier for carrying an original and a second rotary carrier including a copy surface;
- a "read" scanning means movable relative to the first carrier for scanning the original on the first carrier;
- a laser;
- means for passing the information from the "read" scan to said laser to modulate the output of the laser;
- means for causing relative movement between the modulated laser output and the second carrier so as to perform a "write" scan to transfer a pattern derived from the "read" pattern to the copy surface;
- said means for passing information including a random-access memory (RAM) store for storing data obtained in scanning the original;
- measuring means for measuring the circumferential length of the original when on the first carrier store;
- control means for controlling said RAM store in accordance with the output of the measuring means to ensure that each scan of the second carrier is filled by data from the original outside the said gap;
- said measuring means including an artwork counter for storing a count representing the circumferential length;
- and said RAM store control including a write-address counter and a comparator for comparing the output of the artwork counter with the content of the write-address counter, a clock-pulse generator being coupled to said RAM store to initiate store-write operations and store-read operations during scanning, and the comparator initiating an additional store-write operation which also increases the content of the write-address counter each time the content of the write-address counter bears a predetermined relationship with the content of the artwork counter.
Copying apparatus for producing a seamless copy from an unjointed original having leading and trailing edges separated by a gap, said apparatus comprising:
- a first rotary carrier for carrying an original and a second rotary carrier including a copy surface;
- a "read" scanning means movable relative to the first carrier for scanning the original on the first carrier;
- a laser;
- means for passing the information from the "read" scan to said laser to modulate the output of the laser;
- means for causing relative movement between the modulated laser output and the second carrier so as to perform a "write" scan to transfer a pattern derived from the "read" pattern to the copy surface;
- said means for passing information including a store for storing data obtained in scanning the original;
- means for measuring the circumferential length of the original when on the first carrier;
- and store-controlling means connected to the output of the measuring means and effective to control the store in accordance with the measuring means output to ensure that each scan of the second carrier is filled by data from the original outside the gap;
- said means for passing information further including comparator logic having a binary output signal, dependent on the magnitude of the signal from the scanning means, for modulating the output of the laser to cause light to reach the second carrier in one binary state and to prevent light reaching the second carrier in the other binary state, and wherein the comparator logic is constructed to generate an output signal in the first binary state if either y>x(1+k), or x(1-k)<y<x(1+k) provided immediately before y was greater than x(1+k), where y represents the magnitude of the output signal of the scanning means, x represents a predetermined threshold level and k is a predetermined constant, the logic means being constructed to generate an output signal in the second binary state if either y<x(1-k), or x(1-k)<y<x(1+k) provided immediately before y was less than x(1-k).
Dependencies are inferred from the claim text.