Pulse detection and conditioning circuit

A motor pulse sensing arrangement comprising the combination of:

• a motor for producing periodic commutation pulses representing the position of the motor;
• a drive circuit coupled to drive the motor;
• means coupled to the motor for continuously sensing the periodic commutation pulses and including a resistor serially coupled to the motor between the motor and the drive circuit, the resistor forming a junction with the motor at which the periodic commutation pulses are produced;
• and
• means coupled to the junction for recognizing only sensed periodic commutation pulses having an amplitude above a minimum acceptable level.

A pulse detection and conditioning circuit comprising the combination of:

• a balanced differential gain stage, coupled to receive pulses to be detected and conditioned, the balanced differential gain stage being differentially unbalanced by the receipt of a pulse;
• an adjustable differential gain stage coupled to the balanced differential gain stage and being differentially unbalanced by differential unbalancing of the balanced differential gain stage and in a ratio which is adjustable;
• and
• a unity gain comparator coupled to the adjustable differential gain stage and operative to compare differential unbalancing of the adjustable differential gain stage with a threshold value.

Apparatus for tracking the rotational position of an electric motor coupled to a motor drive circuit through a sensing resistor and through an electrical junction located between the motor and the sensing resistor, wherein a motor drive signal is provided between the motor drive circuit and the motor, the drive signal having positive and negative polarity commutation pulses, the apparatus comprising:

• a first differential amplifier having a differential input and having a balanced state, said first differential amplifier being electrically coupled to said electrical junction such that the balanced first differential amplifier becomes unbalanced by the presence of each commutation pulse at said electrical terminal;
• and
• a second differential amplifier coupled to the first differential amplifier and having a pair of output leads, the second differential amplifier providing a bias signal on one of said output leads upon the first differential amplifier becoming unbalanced by a positive polarity commutation pulse and providing a bias signal on the other of said output leads upon the first differential amplifier becoming unbalanced by a negative polarity commutation pulse;
• a transistor circuit having an output and at least one bias input for controlling the signal amplitude at the output, the transistor circuit being coupled at the bias input to at least one of said output leads of said second differential amplifier such that a negative polarity commutation pulse results in the biasing of the transistor circuit and a positive polarity commutation pulse results in a different biasing of the transistor circuit;
• and
• an output terminal coupled to the output of the transistor circuit, the output terminal providing an output signal having an amplitude dependent upon the amplitude of the bias signals applied to the bias input.

Apparatus for tracking the rotational position of an electric motor coupled to a motor drive circuit through a sensing resistor coupled in series with the motor, and through an electrical junction located between the motor and the sensing resistor, wherein a motor drive signal is provided between the motor drive circuit and the motor, the drive signal having positive and negative polarity commutation pulses, the apparatus comprising:

• a first differential amplifier having a differential input and being in a balanced state when the differential input is below a threshold, said first differential amplifier being electrically coupled to said electrical terminal such that the balanced first differential amplifier becomes unbalanced by the presence of a positive polarity or negative polarity commutation pulse at said electrical terminal;
• and
• a second differential amplifier coupled to the first differential amplifier and having first and second output leads, said second differential amplifier providing a bias voltage on said first output lead upon the first differential amplifier becoming unbalanced by a positive polarity commutation pulse, said bias voltage having an amplitude dependent upon the amplitude of said positive polarity commutation pulse, said second differential amplifier providing a second bias voltage on said second output lead upon the first differential amplifier becoming unbalanced by a negative polarity commutation pulse, said second bias voltage having an amplitude dependent upon the amplitude of said negative polarity commutation pulse;
• a first transistor, having a base coupled to said first output lead, for providing an output signal having an amplitude dependent upon the amplitude of the first bias voltage;
• a second transistor, having a base coupled to said second output lead, for providing an output signal having an amplitude dependent upon the amplitude of the second bias voltage;
• and
• a common output terminal responsive to said first and second transistors to provide said output signals of said first and second transistors.

Apparatus for tracking the rotational position of an electric motor coupled to receive a drive signal from a motor drive circuit, the drive signal having commutation pulses, the apparatus comprising:

• a sensing resistor electrically coupled between the motor and the motor drive circuit, in series with the motor and through an electrical junction located between the sensing resistor and the motor;
• a commutation pulse sensing and shaping circuit electrically coupled to sense and shape commutation pulses at said electrical junction;
• and
• a pulse counter electrically coupled to count commutation pulses sensed and shaped by said commutation pulse sensing and shaping circuit;
• wherein the count of the pulse counter is representative of the rotational position of said motor.

Apparatus for tracking the rotational position of an electric motor coupled to receive a drive signal from a motor drive circuit, the drive signal having commutation pulses, the apparatus comprising:

• a sensing resistor electrically coupled between the motor and the motor drive circuit, in series with the motor and through an electrical junction located between the sensing resistor and the motor;
• a commutation pulse sensing and shaping circuit electrically coupled to said electrical junction;
• and
• a pulse counter electrically coupled to said commutation pulse sensing and shaping circuit;
• wherein upon providing a drive signal to said motor, through said electrical junction, commutation pulses in the motor drive signal at said electrical junction are sensed and shaped by said commutation pulse sensing and shaping circuit, the sensed and shaped pulses are counted by said pulse counter and the count is representative of the rotational position of said motor.

Apparatus for tracking and controlling the rotational position of an electric motor that is coupled to receive a drive signal from a motor drive circuit, the drive signal having commutation pulses, the apparatus comprising:

• a sensing resistor electrically coupled between the motor and the motor drive circuit, in series with the motor and through an electrical junction located between the sensing resistor and the motor;
• a commutation pulse sensing and shaping circuit electrically coupled to said electrical junction;
• a pulse counter electrically coupled to said commutation pulse sensing and shaping circuit;
• and
• a drive control circuit electrically coupled with said pulse counter and said motor drive circuit;
• wherein upon providing a drive signal to said motor, through said electrical junction, commutation pulses in the motor drive signal at said electrical junction are sensed and shaped by said commutation pulse sensing and shaping circuit, the sensed and shaped pulses are counted by said pulse counter and a drive signal is provided to said motor drive circuit by said drive control circuit in response to the pulse count of said pulse counter.

A method for tracking the rotational position of an electric motor electrically coupled to receive a motor drive signal from a motor drive circuit, the motor drive signal having commutation pulses, the method comprising the steps of:

• electrically coupling a sensing resistor in series with the motor through an electrical terminal between the sensing resistor and the motor;
• sensing and shaping commutation pulses of the motor drive signal at said electrical terminal;
• and
• counting sensed and shaped commutation pulses, wherein the pulse count is representative of the rotational position of said motor.

A method for tracking the rotational position of an electric motor electrically coupled to receive a motor drive signal from a motor drive circuit, the motor drive signal having commutation pulses, the method comprising the steps of:

• biasing a differential gain amplifier into a balanced state;
• electrically coupling an input of said balanced differential gain amplifier between the motor drive circuit and the electric motor such that the balanced differential gain amplifier becomes unbalanced by the presence of each commutation pulse at said electrical terminal;
• and
• producing an output signal that traverses a predefined reference level upon said balanced differential gain amplifier becoming unbalanced.

An apparatus for comparing a signal to a reference level, the apparatus comprising:

• a first transistor having an input and a first and a second outputs;
• a second transistor having an input and a first and a second outputs, the first outputs of the first and second transistors being coupled to each other, and the second outputs of the first and second transistors being coupled to each other;
• a first device output coupled to the second outputs of the first and second transistors;
• a second device output;
• a third transistor having an input and an output, and being coupled to provide at its output the reference level for coupling to the second device output.