Circuit arrangement for setting a rotatable type carrier over the shortest path of rotation

Claim 1

A circuit arrangement for setting a rotatable type carrier, having character types carried on the periphery thereof, from one setting position by the shortest path of rotation to a new setting position, via a stepping motor, in response to pulse train elements derived from information characters input in binary coded form including new setting position and present setting position characters, comprising: a first comparison means for receiving the new and present position setting characters and emitting a first evaluation signal which is dependent upon the values of said characters relative to one another, including first means for forming the sum of the binary value of the low-value character and the inverted binary value of the higher-value binary character, and second means for forming a binary value corresponding to half the number of possible setting positions of the type carrier; a second comparison means connected to said first and second means and responsive to the binary values formed thereby to emit a second evaluation signal; switching means connected to said first and second comparison means and operable in response to said second evaluation signal to switch through the determined binary spacing quantity as a drive value when the same is equal to or less than half the attainable type carrier setting positions and to switch through the difference quantity between half the number of attainable type carrier setting positions and the determined binary spacing quantity as a drive value when the determined binary spacing quantity is greater than half the number of attainable type carrier spacing positions; Exclusive-or logic means connected to said first and second comparison means and responsive to said first and second evaluation signals emits a control command to produce an oppositely directed rotation of the drive motor, in the presence of a new setting position character, when the new position character is greater than the present position character or when the determined spacing is greater than half the attainable setting positions.