Method and apparatus for precision location of a perforation
First Claim
1. A marker detection apparatus for a marker in a moving media comprising:
- a detector for sensing the marker;
storage means for storing a location magnitude of the marker relative to said detector as sensed by said detector; and
trigger means for triggering storage of the location magnitude in said storage means based on marker characteristics sensed by said detector.
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Abstract
The present invention is a system that includes a quadrant detector with an axis between the detector elements aligned with the direction of film motion. The output of the detector is used by an analog signal processor composed of adders and subtractors to produce signals for detecting the center of the perforation and lateral displacement of the perforation and to provide an illumination adjustment signal. Control logic connected to the analog processor produces signals indicating perforation edge crossings. The center crossing signal is used to control sampling of an illumination adjustment signal and a lateral displacement signal while the edge crossing signals are used for a timing reference for the bottom edge of the film frame. The control logic also detects these trigger signals, controls the capture of the illumination and displacement signals and provides an interrupt to a computer to indicate the capture operation is complete. The computer then retrieves the captured values and uses the values to adjust the position of the image from the film captured by a video detector.
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Citations
17 Claims
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1. A marker detection apparatus for a marker in a moving media comprising:
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a detector for sensing the marker; storage means for storing a location magnitude of the marker relative to said detector as sensed by said detector; and trigger means for triggering storage of the location magnitude in said storage means based on marker characteristics sensed by said detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for determining motion of a perforation in film, comprising:
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a light source shining light through the film; a rectangular quadrant detector over which the perforation moves as the film moves and including first, second, third and fourth adjacent light sensitive elements sensing the light from said light source passing through the perforation, the first and second elements comprising a first pair, the third and fourth elements comprising a second pair, the first and fourth elements comprising a third pair and the second and third elements comprising a fourth pair, the third and fourth pairs having therebetween a motion axis aligned with the direction of perforation motion, the first and second pairs having therebetween a transverse axis perpendicular to the motion axis; an analog processor connected to said quadrant detector and producing Hop, dHop, Weave, Amplitude, Left and Right side analog signals from the outputs of said light sensitive elements, the hop signal crossing zero when the light passing through the perforation falls equally on each side of the transverse axis, the Weave signal having a sign dependent on whether more of the light passing through the perforation falls on one or the other side of the motion axis and having a magnitude corresponding to the proportion of the light falling on a dominant side, the Amplitude signal being proportional to a total amount of light passing through the perforation and falling on said elements; a differentiator connected to said analog processor and producing a differential Hop signal; a first comparator connected to said differentiator and producing top and bottom edge signals when top and bottom edges of the perforation cross the transverse axis; a second comparator connected to said analog processor and producing a zero crossing signal when the Hop signal crosses zero; a trigger control register storing an indication of which of the top, bottom and zero crossing signals should trigger a motion determination cycle; control logic connected to said first and second comparators and to said trigger control register, and producing a time latch signal, a selection signal, a conversion signal, a storage signal and an interrupt signal responsive to the indication, the top and bottom edge signals and the zero crossing signal; a multiplexer connected to said analog processor and said control logic, and selecting one of the Weave, Amplitude, Left, Right, Hop and dHop analog signals responsive to the selection signal; a clock counter counting time; a time latch connected to said control logic and said clock counter and storing the time responsive to the time latch signal; an analog to digital converter connected to said multiplexer and said control logic and converting the selected one of the Weave and Amplitude signals into a digital value response to the conversion signal; a storage latch connected to said analog to digital converter and said control logic and storing the digital value responsive to the storage signal; and a computer connected to said control logic, said time latch and said storage latch and retrieving the time and the digital value responsive to the interrupt signal.
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16. An apparatus for determining characteristics of a marker moving along a motion axis of a moving media, comprising:
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sensing means for sensing a center, a top edge and a bottom edge of the marker; time storage means for storing a time at which one of the center, top edge and bottom edge are sensed; and motion storage means for storing an amount of motion of the marker transverse to the motion axis when the time is stored.
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17. A method of determining characteristics of a marker moving along a motion axis of a moving media, comprising the steps of:
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(a) sensing a center and top and bottom edges of the marker; (b) storing a time at which the one of the center top edge and bottom edge are sensed; and (c) storing one of an amount of motion of the marker transverse to the motion axis and an amplitude of proportional to a size of the marker.
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Specification