Abstract: A pulse width modulation circuit includes a transistor pass element alternately switched on and off by an oscillator and connecting a power source to a load. Current through the transistor pass element is compared to a reference signal by a comparator. If the current through the transistor pass element exceeds the reference signal, the comparator generates a fault signal, and the transistor pass element is switched off for the remainder of the cycle. After a predetermined number of faults, the transistor pass element is switched off for a plurality of cycles. The pulse width modulation circuit prevents damage to the transistor pass element caused by the low initial resistance of the load and supplies sufficient current to slowly heat the load to steady state operation. This also allows for downsizing of the pass element for steady state conditions thereby saving product cost.

Abstract: An optical anti-theft system incorporates a member having a plurality of reflective surfaces. The plurality forms a pattern corresponding with the security code. The system additionally incorporates a base for receiving the member. The base incorporates a light source for generating a light beam to illuminate the plurality of reflective surfaces, and a light detector for sensing the illuminated plurality of reflective surfaces and for initiating a security function in response to the sensed illuminated plurality of reflective surfaces having the pattern.

Abstract: A power window system employs a computer based control that receives signals from a window position sensor. As the window moves, the position sensor produces periodic signals as an output. The computer cyclically looks for a change in the frequency of the signals as an indication that the window is obstructed and decelerating. Based on the instantaneous deceleration, the computer recalls a stored value for motor force. The recalled forces are accumulated in synchronism with the position sensor output during the deceleration, manifesting the force applied to the obstruction as the window presses on it. The window is reversed when the accumulated force exceeds a stored value. The uppermost window position is a stored value for the position sensor output obtained when the window is closed for the first time. Each time the window is closed thereafter, an offset is added to that value, the sum defining the point at which the window engages the window seal.