Patent ID: 6184663
Filing Date: 2001-02-06
Classification: H05B,Y02B,Y10S

Abstract:
An apparatus for driving an electric load, comprising:a switch means interposed in a current feed path from a direct-current power source to the electric load for continuously varying an electric current flowing along the current feed path:a sensing resistor connected in series with the switch means for detecting a load current as a voltage value, the load current flowing into the electric load via the switch means:a trapezoidal wave generation circuit for generating a trapezoidal wave signal in response to externally applied commands to turn on and turn off the electric load, the trapezoidal wave signal having a trapezoidal waveform, the trapezoidal wave signal gradually varying from a first predetermined voltage to a second predetermined voltage when the electric load is turned on, the trapezoidal wave signal gradually varying from the second predetermined voltage to the first predetermined voltage when the electric load is turned off; anda control means for comparing the trapezoidal wave signal generated by the trapezoidal wave generation circuit and the voltage value provided by the sensing resistor, and for controlling the switch means in response to a result of the comparing so that the load current will vary in a trapezoidal shape in accordance with the trapezoidal wave signal.