Document feed for optical scanner

In a system for optically reading data printed in transversely extending lines longitudinally spaced apart on a document comprising a scanning head including electro-optical means for scanning and reading data, means for supporting said scanning head for transverse movement relative to such a document and along each such line of data, drive means for moving such a document longitudinally relative to said scanning head, said drive means including friction drive roller means for engaging and moving such a document, a motor, means for drivingly connecting said motor to said roller means, and control means for said motor, the improvement in which said motor is a stepper motor having an output shaft which is advanced one step about its axis each time said motor is pulse and including a plurality of coils which are sequentially energized to move said motor output shaft each step, said control means including a ring counter having a plurality of outputs associated respectively with said coils, a driver for connecting each ring counter output to its associated motor coil and including means for producing pulses at a first predetermined frequency and pulses at a second and lower frequency, and a speed selector circuit for selecting which of said first and second frequency pulses are to be fed to said motor, and optical means for detecting lines of data on such a document and stopping longitudinal movement of such document, said optical means being operatively connected to said generating means and effective to control the pulse output of said generating means.

In a system for optically reading data printed in transversely extending lines longitudinally spaced apart on a document comprising a scanning head including electro-optical means for scanning and reading data, means for supporting said scanning head for transverse movement relative to such a document and along each such line of data, drive means for moving such a document longitudinally relative to said scanning head, said drive means including friction drive roller means for engaging and moving such a document, a motor, means for drivingly connecting said motor to said roller means, and control means for said motor, the improvement in which said motor is a stepper motor having an output shaft which is advanced one step about its axis each time said motor is pulsed and including a plurality of coils which are sequentially energized to move said motor output shaft each step, said control means including a ring counter having a plurality of outputs associated respectively with said coils, a driver for connecting each ring counter output to its associated motor coil and means for generating motor energizing pulses including an oscillator for producing pulses at a first predetermined frequency, a divider circuit for receiving such pulses and providing an output of pulses at a second and lower frequency, and a speed selector circuit for selecting which of said first and second frequency pulses is to be fed to said motor, said selector circuit being operatively connected to said oscillator and said divider circuit, and optical means for detecting lines of data on such a document and stopping longitudinal movement of such document, said optical means being operatively connected to said generating means and effective to control the pulse output of said generating means.