Monitoring circuit for a door operating D.C. electric motor
First Claim
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1. A monitoring circuit for a door operating D.C. electric motor, said circuit comprising first means for detecting the back EMF of the motor and producing a load signal indicative of the magnitude thereof;
- and second means for detecting the time rate of change of the load signal and issuing an obstruction signal if the magnitude of the time rate or change of the load signal exceeds a predetermined value.
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Abstract
A monitoring circuit for a door operating D.C. electric motor, the circuit comprises a first means for detecting a back EMF of the motor and producing a load signal indicative of the magnitude of the back EMF, a second means for detecting the time rate of change of the load signal and issuing an obstruction signal if the magnitude of the time rate of change of the load signal exceeds a predetermined value.
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15 Claims
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1. A monitoring circuit for a door operating D.C. electric motor, said circuit comprising first means for detecting the back EMF of the motor and producing a load signal indicative of the magnitude thereof;
- and second means for detecting the time rate of change of the load signal and issuing an obstruction signal if the magnitude of the time rate or change of the load signal exceeds a predetermined value.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
Specification