US Patent 7516939 Dual detection sensor system for washroom device

A detection system for a washroom device evaluates outputs from an active sensor and a passive sensor to determine whether to activate the device (e.g., operate a valve in a sink or a lavatory). The active sensor has a transmitter that directs a light beam to a selected zone and a receiver that detects whether the light beam is reflected back to the sensor. The passive sensor detects changes in a temperature signature around the washroom device. A controller evaluates the outputs from both the active sensor and the passive sensor to determine how to operate the washroom device.