Stepping motor having an odd number of windings,the windings being energized at all times

Claim 2

A stepping motor arrangement comprising a motor having an odd number P of star-connected field windings, the effective star point being connected to a reference voltage level, switchable means for connecting each of the windings alternately to first and second voltage levels, the first voltage level being positive with respect to the reference and the second voltage level being negative with respect to the reference but of equal magnitude to the first voltage level, and logic circuit means, driven by a succession of pulses, for controlling the switchable means to connect the windings in due order to the first and second voltage levels for stepping the motor through 2P steps per revolution, the windings being energized at all times.

Claim 3

A stepping motor arrangement as claimed in claim 1 wherein the logic circuit comprises a number, equal to the number of field windings, of bistable elements each having first and second outputs, and being controlled by signals to not more than two inputs comprising respectively a transfer signal input and a switching input, each said bistable element providing an output signal alternately at the first or second output in dependence upon the signal level sensed at the transfer signal input, the bistable element taking up the state dictated by the transfer input signal only when a signal pulse is applied to the said switching input, a generator of a succession of signal pulses being connected to the switching inputs of the bistable elements, transfer input signal for one bistable element being derived from another bistable element so that the succession of signal pulses applied to the switching inputs causes a cyclic sequence of changes of state of the bistable elements, the field windings being connected in due order to the two alternative voltage levels through a switching mechanism controlled by the outputs of the bistable elements.

Claim 4

A stepping motor arrangement as claimed in claim 2, wherein certain of the field windings are switched under the control of the first outputs of the bistable elements associated respectively with those field windings, while the other field windings are switched under the control of the second outputs of the respective associated bistable elements.

Claim 5

A stepping motor arrangement as claimed in claim 3, wherein alternatively operable configurations of interconnection between the outputs and the transfer inputs of the bistable elements are provided corresponding to forward and reverse driving cycles respectively, and means are provided for selecting which configuration of interconnection is rendered operative.