Electric motor having Hall generators and control circuit

Claim 1

An electric motor having Hall generators and a control circuit comprising: rotor means including a rotor having an inner periphery, a pair of permanent magents of different polarities secured to said inner periphery of said rotor, said pair of permanent magents being opposite to each other and angularly extending in a limited arc along said inner periphery of said rotor to produce mangetic fluxes of different polarities, said rotor having a pair of unmagnetized portions producing no magnetic flux angularly extending over a limited arc along said inner periphery between said pair of permanent magnets and being opposite to each other; armature means including an armature having three poles and a coil wound around each of said poles, said coils being connected to each other; Hall generator means including a pair of Hall generators angularly spaced from each other with respect to the axis of rotation of said rotor, said Hall generators being responsive to a first one of said permanent magnets to produce a first electric signal and being responsive to a second one of said permanent magnets to produce a second electric signal, said Hall generators being responsive to said unmagnetized portions of said rotor to produce no electric signal; and control circuit means including a control circuit having two pairs of comparator devices, a first pair of comparator devices being electrically connected to one of said Hall generators, a first one of said first pair of comparator devices being responsive to said first electric signal produced by said one of said Hall generators to produce a first electric output, and a second one of said first pair of comparator devices being responsive to said second electric signal produced by said one of said Hall generators to produce a second electric output, said first and second ones of said first pair of comparator devices being responsive to an absence of an electric signal from said one of said Hall generators to produce no electric output, a second pair of comparator devices being electrically connected to the other of said Hall generators, a first one of said second pair of comparator devices being responsive to said first electric signal produced by said other of said Hall generators to produce a first electric output, and a second one of said second pair of comparator devices being responsive to said second electric signal produced by said other of said Hall generators to produce a second electric output, said first and second ones of said second pair of comparator devices being responsive to an absence of an electric signal from said other of said Hall generators to produce no electric output, said control circuit means further including a logic circuit having a pair of gates each having three inputs selectively connected to said outputs of said first and second pairs of comparator devices, each of said gates producing an electric output when said three inputs receive no electric output from said first and second pairs of comparator devices to which said three inputs are selectively connected, each of said gates producing no electric signal when one of said three inputs receives an electric output from said first and second pairs of comparator devices to which said three inputs are selectively connected, said electric outputs of said first and second pairs of comparator devices and of said pair of gates being connected to said coils of said three-pole armature and cooperating to control an electric current flowing through said coils in order to continuously rotate said rotor means.