Microfilm search device and method

A microfilm search device for searching a desired frame from a microfilm by detecting the presence of frames from a density change in the running direction of the microfilm, comprising:

• a) an encoder for outputting a sampling signal for a predetermined feeding amount of the microfilm;
• b) a pair of optical fibers whose end faces are opposed to each other while the microfilm is placed between the end faces within a frame travel width;
• c) a light source for guiding light to one of said optical fibers;
• d) a photosensor for detecting a quantity of light incident on the other optical fiber to output a density signal;
• e) a binarizing section for binarizing the density signal into a white or black signal in synchronization with said sampling signal, the white signal representing a film transparent portion and the black signal representing a film non-transparent portion;
• f) a determination section for detecting a frame dimension or a dimension between frames based on the binarized density signal and comparing the dimension with a set value to determine the presence of frames and output a determination signal;
• and
• g) a searching section for searching for the desired frame based on said determination signal;
• wherein said determination section corrects the dimension to shorten the frame dimension or the dimension between frames obtained from the binarized density signal, when detecting the frame dimension or the dimension between frames from the length of a portion where the white signals are continuously obtained;
• wherein said determination section corrects the dimension to lengthen the dimension when detecting the dimension from the length of a portion where the black signals are continuously obtained;
• and
• wherein said determination section compares the corrected dimension with said set value to determine the presence of frames.

A frame/between-frames dimension detecting method for use in a microfilm search device for detecting the presence of frames from a density change in the running direction of a microfilm, comprising the steps of:

• guiding light to one of a pair of optical fibers whose end faces are opposed to each other with the microfilm placed therebetween;
• detecting the quantity of light incident upon the other optical fiber with a photosensor to obtain a density signal;
• binarizing the density signal into a white or black signal in synchronization with a predetermined feeding amount of the microfilm;
• obtaining a dimension of a frame or an interspace between frames based on the binarized density signal;
• correcting the dimension to shorten, when the dimension is detected from the length of a portion where the white signals are continuously obtained;
• and
• correcting the dimension to lengthen, when the dimension is detected from the length of a portion where the black signals are continuously obtained.

A microfilm search device for searching a desired frame from a microfilm by detecting the presence of frames from a density change in the running direction of the microfilm, comprising:

• a) an encoder for outputting a pulse signal for a predetermined feeding amount of the microfilm;
• b) a density sensor for detecting the film density of the microfilm along the running direction of the microfilm to output a density signal;
• c) a binarizing section for binarizing the density signal into a white or black signal in synchronization with said pulse signal, the white signal representing a film transparent portion and the black signal representing a film non-transparent portion;
• d) a counter for counting said pulse signal to obtain a film travel amount, said counter being reset at the time of frame detection and at the time of film reversing;
• e) a reverse detector for detecting a change of the film running direction to reset said counter;
• f) a determination section for counting the number of either one of the binarized signals based on said counter to determine the presence of frames and output a determination signal;
• and
• g) a searching section for searching for the desired frame based on said determination signal.