Abstract: A presence detecting apparatus and method are disclosed, the apparatus including an emitter array and receiver array configured, oriented and shielded to provide an effective detection area characterized by a truncated elliptical footprint, a background compensation network for automatically compensating for variations in environmental conditions in the detection area to provide a substantially constant detection sensitivity, and discriminating circuitry for discriminating signals indicative of a body in the detection area from transient and steady state signals. The emitter circuits and receiving and detecting circuits are capable of asynchronous operation, and the receiver array and detector array are housed so that the receiver array is substantially isolated from selected electromagnetic signals from the detector array.

Abstract: A speed control apparatus for controlling the rate of motion of a door is disclosed which includes a shaft connected with the door by a gear train for causing rotation of the shaft at a preselected relative rate of rotation related to the rate of motion of the door by a preselected ratio, a braking assembly including a brake drum spaced from the shaft and first and second brake shoes pivotably connected at one end thereof with a carrying member attached to the shaft and having a single biasing spring adjustably connected between the other ends thereof, the brake shoes having a contact surface made of a non-asbestos friction material for contacting the brake drum when a selected rate of rotation of the shaft is exceeded, and an improved housing which is more efficiently sealable against invasion of moisture into the housing and the escape of lubricants from the housing.