Method and apparatus for film weave correction

A method for detecting the position of sprocket hole in a film recording or reproducing apparatus which employs a continuous motion film drive comprising the steps of

• causing the scanning beam to scan the sprocket hole in a vertical direction to detect a first vertical edge of the sprocket hole,
• causing the scanning beam to scan the sprocket hole in a vertical direction to detect a second vertical edge of the sprocket hole,
• positioning the scanning beam within the sprocket hole based on the detection of a vertical edge, and
• causing the scanning beam to scan the sprocket hole in a horizontal direction.

An apparatus for determining the position of a sprocket hole in a film recording or reproducing apparatus which employs a continuous motion film drive comprising

• a source of a scanning beam for scanning the sprocket hole,
• a scanning beam for scanning at least the sprocket hole,
• means to divert the scanning beam to sweep in a vertical direction to detect at least a vertical edge of the sprocket hole,
• means to position the scanning beam in the sprocket hole,
• means to divert the scanning beam to sweep in a horizontal direction to detect a horizontal edge of the sprocket hole.

An apparatus for determining the position of a sprocket hole in a film recording or reproducing apparatus which employs a continuous motion film drive comprising

• a source of a scanning beam for scanning the sprocket hole,
• a scanning beam for scanning at least the sprocket holes;
• means to divert the scanning beam to sweep in a vertical direction to detect upper and lower vertical edges of the sprocket hole,
• means to position the scanning beam in the center of the sprocket hole, and
• means to divert the scanning beam to sweep in a horizontal direction to detect a horizontal edge of the sprocket

A method of detecting the edge of a sprocket hole in a film recording or reproducing apparatus which employs a continuous motion film drive, in which a scanning beam scans the film and sprocket hole, and a detector which measures the intensity of the transmitted beam, comprising the steps of

• detecting the level of the transmitted beam,
• generating a reference signal from the level of the transmitted beam which reference signal is less than the level of the transmitted beam,
• comparing the level of the transmitted beam with the reference signal, and
• indicating a crossing of the scanning beam with the sprocket hole edge when the transmitted beam is equal to or less than the reference signal.

A apparatus for detecting the crossing of a detector beam with the edge of a sprocket hole in a film recording or reproducing apparatus which employs a continuous motion film drive including electronic means comprising

• a clamping amplifier,
• a fast peak detector,
• means to reduce the signal from the fast peak detector, and
• a comparator for comparing the output of the clamping amplifier and the signal from the fast peak detector as reduced.

A method for reducing error in application of a weave correction signal in film recording or reproducing apparatus which employs a continuous motion film drive for film containing frames comprising

• defining a window of acceptable weave correction signals,
• comparing the weave correction signal for the current film frame with a comparator,
• applying the weave correction signal for a current film frame if the weave correction signal is within the window of acceptable weave correction signals, and
• applying the last weave correction signal which was within the window of acceptable weave correction signals if the weave correction signal for the current film frame is not within the window of acceptable weave correction signals.

An apparatus for elimination of horizontal and vertical film weave in a film reproduction apparatus which detects the position of the sprocket hole of the film by sensing transmission of light through the film to generate a current weave correction signal comprising

• a scanning beam in the form of a weave corrector cross,
• a detector for said scanning beam,
• an edge detector comprising a fast peak detector, and a comparator for comparing the output of the fast peak detector and said detector,
• means for defining a window of acceptable weave correction signals,
• means to apply the current weave correction signal if it is within the window of acceptable weave correction signals, and
• means to apply the last weave correction signal which was within said window if the current weave correction signal is not within said window.