Quotation board system

Claim 1

Apparatus adapted to control the extent and direction of rotation of a single reversible electric motor which in turn rotates an endless belt having a set of spaced apart digits a... n thereon, the set containing n different integers arranged in an ordered sequence, to index any selected first digit at a display station and thereafter to index a second digit to said station, said apparatus minimizing the time required to rotate the belt to index the second digit for display by rotating the belt in one direction or another to minimize belt movement, said apparatus comprising: first means to produce a first unidirectional voltage of given polarity and having any one of n different discrete values, each value representing a different digit, said first voltage designating said first digit; second means to produce a second unidirectional voltage of like polarity and having any one of n different discrete values, each value representing a different digit, said second voltage designating said second digit; third means for comparing the first and second voltages to produce a control voltage having a first fixed null value when the first and second voltages Are equal, said control voltage having a range or values differing from the null value and dependent upon the difference between the first and second voltages when the first and second voltages are unequal; fourth means responsive to said control voltage and coupled to said motor to cause the motor to rotate in one direction to a position at which the second digit is indexed when the first and second voltages are unequal and the value of the control voltage exceeds that of a fixed reference voltage and to cause said motor to rotate in the opposite direction to a position at which the second digit is indexed when the first and second voltages are unequal and the value of the control voltage falls below that of said reference voltage, said motor remaining in fixed position without rotation when the first and second voltages are equal.