PURPOSE: To prevent the infeasiability of distance detection due to battery exhaustion and assure safety by transmitting the signal indicating the discharged state of a battery from a transponder to a transceiver side.
CONSTITUTION: A transceiver 10 is fitted at the rear section of a hydraulic shovel 1, and a transponder 20 is fitted to the helmet of a worker 2. The transceiver 10 has an arithmetic circuit measuring the distance D0 to the transponder 20 and transmits the calculated distance D0 to the control device 4 of a driver's cab 3. The control device 4 compares the distance D0 with the prescribed reference value and drives a warning device on the driver's cab 3 to display a danger when the transponder 20 (worker 2) is approaching. When a battery stored in the transponder 20 is made the consumed state, i.e., the so-called battery exhausted state, the control device 4 reports it to an operator. The transponder 20 has the detecting function of the remainder (discharged state) of the battery and transmits the detected data of the battery remainder to the transceiver 10 side on the transmitted wave.
SUGAWARA KAZUHIRO
TANAKA YASUO
AOKI SHIGENORI
