Apparatus for reading bar codes recorded on photographic film

In a photographic apparatus comprising a film carrier for holding a photographic film and a film feeding mechanism for feeding said photographic film in a film feeding direction, an apparatus for reading a DX bar code recorded along one major edge of said photographic film and a frame number bar code recorded along the other major edge, the DX bar code comprising a clock track and a data track, the frame number bar code comprising bars and spaces, and being represented by binary signals "1" and "0" which values are determined in correspondence to the width of the bars and spaces, wherein a narrower bar o space of said frame number bar code has the same width as that of each ar of said DX bar code, and a wider bar or space of said frame number bar code has a width two times as large as that of each bar of said DX bar code, the apparatus comprising:

• two bar code sensor units mounted at opposite sides of a path through which said photographic film passes, both of said bar code sensor units having the same construction, each said bar code sensor unit including first and second photosensor arrays, said first and second photosensor arrays being located along said path at positions corresponding to said clock track and said data track, respectively, along a line perpendicular to said film feeding direction wherein each said photosensor array comprises four photosensors disposed at a constant pitch said direction of movement of said photographic film, said pitch allowing two of said four photosensors to face one bar of said DX bar code at the same time;
• a plurality of differential amplifiers for generating a difference signal between the output signals from two adjacent photosensors of said photosensor array;
• a plurality of window comparators each generating a first signal of high level "H" when the output signal from each said differential amplifier is higher than a first reference voltage, and a second signal of low level "L" when the output signal from said differential amplifier is lower than a second reference voltage which is lower than said first reference voltage;
• means for generating said bar code data by sampling said first and second signals from said window comparators when either of said first and second signals from said window comparators changes;
• means for automatically discriminating between the DX bar code data and the frame number bar code data, based on two types of said bar code data read out with said two bar code sensors, and obtaining a film type from said discriminated DX bar code data and a frame number from said frame number bar code data;
• and
• means for judging a position of said photographic film in said film carrier based on said read-out two types of said bar code data, and means for outputting an alarm in response to an abnormal position of said photographic film in said film carrier.