Abstract: An optical safety beam method and system. A transmitter periodically sends bursts of light pulses with varying strengths. The receiver analyzes the received light pulses to automatically adjust its sensitivity and to detect when the light path is partially obstructed even when there are stray light pulse reflections that reach the receiver.

Abstract: In an IR communication network, a method is described to optimize channel performance in the presence of strong and varying IR interference. The method controls of the channel gain based on quantitative measurement of the channel noise.

Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between the phase/frequency comparator and the voltage controlled oscillator causes the voltage controlled oscillator to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between the fixed frequency and the operating frequency.

Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between said fixed frequency and said operating frequency.

Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between said fixed frequency and said operating frequency.

Abstract: In an IR communication network, a method is described to optimize channel performance in the presence of strong and varying IR interference. The method controls of the channel gain based on quantitative measurement of the channel noise.

Abstract: A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between said fixed frequency and said operating frequency.

Abstract: An automatic door opening safety system particularly for use with garage doors is provided. The garage door includes a leading edge that moves from the open position, where the leading edge defines the top of the opening and a closed position, where the leading edge contacts the ground. A controller is provided for controlling movement of the door. An activation member provides an input to the controller to initiate movement of the door. A non-contact detector detects whether an obstruction is in the path of the door. The non-contact detector is positioned in front of the leading edge of the door, such that obstructions are detected at a predetermined distance in front of the leading edge of said door.