| 摘要 |
A lighting control unit comprises a light sensor and a wireless receiver, and is adapted to output a control signal that is active when the light sensor detects a low light condition or the wireless receiver detects an incoming activation signal. The wireless receiver is preferably adapted to respond to an encoded signal, in order to prevent false activations. The wireless receiver can be one adapted to distinguish two incoming signals, a first signal being the activation signal and a second signal on receipt of which the control unit is adapted to de-activate the control signal regardless of the state of the light sensor. This enables a further mode of operation in which the lamp is disabled, such as for maintenance work. In a second aspect, the present invention provides a lighting control unit comprising a wireless receiver adapted to output a first control signal that is active when an incoming signal is detected and a light sensor adapted to output a second control signal that is active when a low light condition is detected, and an OR operator to which the two control signals are delivered. The wireless receiver can be one comprising two channels, a first channel adapted to output the first control signal and a second channel that is adapted to output an over-ride signal, the invert of which is delivered to an AND operator together with the output of the OR operator. Generally, a radiofrequency receiver is the most suitable form of wireless receiver. An area lighting system incorporating such a lighting control unit, and a street light unit comprising an upright column and, at an upper region thereof, a lamp and such a lighting control unit are also described. |
