Patent ID: 9530309
Filing Date: 2016-12-27
CPC Classification: G01V,G08C,H03K

Claim Text:
1. An object detection system in which projectors and optical receivers of a plurality of multiple-optical-axis photoelectric sensors are connected to each other through communication lines to cause detection processes of the respective sensors to sequentially proceed on the basis of communication between the sensors, wherein the projector and the optical receiver of each of the multiple-optical-axis photoelectric sensors comprise timers configured to determine timings of operations in their own devices, respectively, the projector and the optical receiver in each of the multiple-optical-axis photoelectric sensors available to be a master device, with only one of the projectors and optical receivers individually functioning as the master device, the master device comprises a definition information producer configured to produce definition information that determines timings of detection processes in the respective devices including its own device on the basis of relationships between sensors in the system and the number of optical axes of the respective sensors, a definition information transmitter configured to transmit the definition information to the other devices in the system respectively, a timer controller configured, while recognizing a circulating period of the detection processes in the respective sensors on the basis of a measured time obtained by the timer of its own device and the definition information, to simultaneously transmit commands to require the operations of the timers to be synchronized with each other to the other devices in response to elapse of a time corresponding to a period in which the circulating period proceeds by a predetermined cycle, and a master detection controller configured to determine a timing at which the detection process should be executed on the basis of definition information matched with its own devices to execute the detection process, and each of the devices except for the master device comprises a storage configured to store the definition information transmitted from the master device, a timer corrector configured to correct the timer of its own device in response to a command from the master device, and a detection controller configured to determine a timing at which the detection process should be executed with reference to a time point at which the timer is corrected on the basis of the definition information matched with its own device to execute the detection process.