Self-referencing start of plot system and method

Claim 1

A three portion mark for use on a print medium to indicate the start of plot of print lines on the print medium, comprising: a first portion of said mark above a reference line; a second portion of said mark beneath the reference line directly following in space the first portion; and a third portion above the reference line, said third portion being spaced from the first portion by the width of the second portion.

Claim 10

A method for generating a start of plot signal for use on a print medium, comprising the steps of: providing a three portion SOP mark on said print medium, said three portion SOP mark having in sequence a first portion above a reference line, a second portion below said reference line and a third portion above said reference line; said first portion of said mark, and computing a first quantity proportional to the size of the area sensed; sensing said second portion of said mark and computing a second quantity proportional to the size of area sensed; computing a third quantity proportional to the difference of the peak values of said first and second quantities; sensing said third portion of said mark and providing a fourth quantity proportional to the size of area sensed; and issuing a start of plot signal when said fourth quantity equal said third quantity.

Claim 23

A system for marking positions on a moving print medium, comprising: a series of equally spaced tick marks printed on said print medium, each of said tick marks having a width substantially equal to the spacing between successive tick marks; a plurality of patterns, mounted on an apparatus, each pattern substantially the same as a section of said series of tick marks, and each of said plurality of patterns is positioned such that when one of said plurality of patterns is matched against said series of tick marks as said series of tick marks moves with said moving print medium, the rest of said plurality of patterns are each lagging a different angular distance from said moving series of tick marks; projecting means for superimposing an image of said moving series of tick marks on to said apparatus; and sensing means for sensing the position of said image of said moving series of tick marks relative to each of said plurality of patterns, and providing a signal whenever said image of said moving series of tick marks coincides substantially with one of said plurality of patterns.

Claim 30

An apparatus for providing a timing means based on sensing a tracking line formed by a series of equally spaced marks printed on a moving printed medium comprising: first sensor means situated at a first location providing an output signal when said sensor means sense the passing of one of said series of equally spaced mark moved past said first location, such that as said series of equally spaced marks pass said first location at a periodic rate, said first sensor provides a first series of output signals at said periodic rate; second sensor means substantially the same as said first sensor means situated at a second location such that as said series of equally spaced marks pass said second location at said periodic rate, said second sensor means provides a second series of periodic signals of said periodic rate having a first time lag with respect to said first series of periodic signals by 1/4 time period between successive signals of said first series of periodic signals; third sensor means substantially the same as said first sensor means situated at a third location such that as said series of equally spaced marks pass said third location at said periodic rate, said third sensor means provides a third series of periodic signals of said periodic rate having a second time lag with respect to said first series of periodic signals by 1/2 the time period between successive signals of said first series of periodic signals; fourth sensor means substantially the same as said first sensor means situated at a fourth location such that as said series of equally spaced marks passed said fourth location at said periodic rate, said fourth sensor means provides a fourth series of periodic signal at said periodic rate having a third time lag said first series of periodic signals by 3/4 the time period of said first series of periodic signals, and such that said first, second, third and fourth series of periodic signals are in quadrature relation with each other; and signal processing means for combining said first, second, third and fourth series of periodic signals in time to provide a fifth series of periodic signals, each signal of said fifth series of periodic signals is generated in response to a signal from said first, second, third, and fourth series of periodic signal, and for providing said fifth series of periodic signal as said timing means.

Claim 34

An apparatus for providing a timing means as in any one of Claims 30 to 33 , further comprising sense means for providing a SOP signal when a three portion start of plot mark is sensed, such that said fifth series of periodic signal may begin to actuate mechanisms after said SOP signal is provided.