Servomechanism with driving rotor winding and braking rotor winding

Claim 2

A servomechanism including, an electric motor of the commutator type having a rotor with a pair of rotor windings, separate commutator means connected to each of said rotor windings, circuit means adapted to receive a DC driving signal current and connected to one of said rotor windings through the respective commutator means for rotating said rotor in at least one direction, and a resistance circuit connected to the other of said rotor windings through the other respective commutator means and operative upon rotation of the rotor to produce an electrical torque on said rotor for braking said rotor at least when the DC driving signal current in said one of said rotor windings drops below a given value.

Claim 3

The servomechanism as defined in claim 1, wherein said resistance circuit includes at least one switch means, said switch means connected to said circuit means and operated by the driving signal current, whereby said resistance circuit is closed by said switch means as soon as the driving signal current falls below a given value.

Claim 4

The servomechanism as set forth in claim 2 wherein as soon as said resistance circuit is closed by said switch means, said resistance circuit produces in said other of said rotor windings the electrical braking torque.

Claim 5

The servomechanism as defined in claim 1, wherein the driving signal current is dependent on the difference between the desired opening of a camera diaphragm and the actual opening of the diaphragm, and the motor controls the diaphragm opening.

Claim 6

A servomechanism including an electric motor of the commutator type having a rotor with a pair of rotor windings, separate commutator means connected to each of said rotor windings, circuit means adapted to receive a driving signal current and connected to each said rotor winding through the respective separate commutator means for energization by the driving signal current, each said rotor winding disposed on said rotor such that respective energization causes the motor to rotate in a respective different direction, a respective resistance circuit shunting each said rotor winding through the respective commutator means, and upon rotation of the rotor by one of said rotor windings the resistance shunting circuit of the other of said rotor windings operative to produce an electrical torque on said rotor for braking said rotor at least when the driving signal current in said one of said rotor windings drops below a given value.

Claim 7

A servomechanism including an electric motor of the commutator type having a rotor with a pair of rotor windings, separate commutator means connected to each of said rotor windings, circuit means adapted to receive a driving signal current and connected to each said rotor winding through the respective separate commutator means for energization by the driving signal current, each said rotor winding disposed on said rotor such that respective energization causes the motor to rotate in a respective different direction, a respective resistance circuit shunting each said rotor winding through the respective commutator means, and upon rotation of the rotor by one of said rotor windings the resistance shunting circuit of the other of said rotor windings operative to produce an electrical torque on said rotor for braking said rotor at least when the driving signal current in said one of said rotor windings drops below a given value.

Claim 8

The servomechanism as defined in claim 5, including a respective unidirectional conductor connected in series with each said respective shunt resistanCe for preventing driving signal current from flowing through the respective said shunt resistance.

Claim 9

The servomechanism as defined in claim 6, including a respective transistor connected between each said rotor winding and said circuit means for enabling energization of the respective said rotor winding when the respective transistor conducts, and control circuit means connected to said circuit means and adapted to produce the driving signal current to bias each said transistor to conduct or not to conduct in dependence on the direction in which the motor is to turn.

Claim 10

The servomechanism as defined in claim 7, wherein said control circuit means includes a differential amplifier having a pair of output terminals respectively connected to said respective transistors.

Claim 11

The servomechanism as set forth in claim 8, in which said control circuit means includes an electrical bridge having an output circuit connected to said differential amplifier for driving the same, a source of potential energizing said electrical bridge, said electrical bridge including a photoelectric element whereby said electrical bridge is operative to produce a driving signal current in the said output circuit dependent on the amount of illumination received by said photoelectric element.

Claim 12

The servomechanism as defined in claim 9, wherein said source of potential includes a source of reference potential and, with respect to said source of reference potential, a source of maximum potential and a source of an intermediate potential, said electrical bridge is connected across said sources of maximum and reference potentials, and said pair of rotor windings are connected across said sources of maximum and intermediate potentials via said respective transistors.

Claim 13

A servomechanism including an electric motor of the commutator type having a rotor with a pair of rotor windings, separate commutator means connected to each of said rotor windings, circuit means adapted to receive a driving signal current and connected to one of said rotor windings through the respective commutator means for rotating said rotor in at least one direction, a resistance circuit connected to the other of said rotor windings through the other respective commutator means and operative upon rotation of the rotor to produce an electrical torque on said rotor for braking said rotor at least when the driving signal current in said one of said rotor windings drops below a given value, a relay, said relay including a winding connected to said circuit means and adapted to be energized by the driving signal current, said relay including a contact connected in series with said resistance circuit, and said contact being closed to complete said resistance circuit when the driving signal current falls below a given value.

Claim 14

A servomechanism including an electric motor of the commutator type having a rotor with a pair of rotor windings, separate commutator means connected to each of said rotor windings, circuit means adapted to receive a driving signal current and connected to one of said rotor windings through the respective commutator means for rotating said rotor in at least one direction, a resistance circuit connected to the other of said rotor windings through the other respective commutator means and operative upon rotation of the rotor to produce an electrical torque on said rotor for braking said rotor at least when the driving signal current in said one of said rotor windings drops below a given value, a relay, said relay including a winding connected to said circuit means and adapted to be energized by the driving signal current, said relay including a contact connected in series with said resistance circuit, and said contact being closed to complete said resistance circuit when the driving signal current falls below a given value.