Patent EP-0029560-A1 (EP)
Inventor: BERTHOLD RAINER DIPL-PHYS
IPC: G07C9/00
Filed: 1980-11-15
Abstract: 1. Method for detecting and counting objects which are each case equipped with a response device (2) which is provided with a power and signal receiving device (21, 22) a storage device (26) which contains a multi-position identification allocated to the respective object, a comparing device (29) and a signal emitting device (27), in which method - a sequence of systematically varying interrogation signals is generated by a central interrogation device (1) which is provided with a power and signal transmitting device (11, 16), a signal receiving device (12), and a signal processing devic (13-15, 17) containing a signal generator (15) and a signal memory (14), - each interrogation signal of the sequence is compared with the stored identification by means of the comparing device (29) in each response device (2), - an identity signal is sent by the response device (2) concerned to the interrogation device (1) in the case of an agreement between an interrogation signal and a stored identification and - if an identity signal is received by the interrogation device, the associated interrogation signal is stored in the signal memory (4), characterized in that - in a number, corresponding to the number of positions of the identification, of successive interrogation cycles, in each case a number of interrogation signals is generated during each cycle, which interrogation signals are in each case composed of an address section and a data section and in which arrangement the address section determines the identification positions to be used for the comparison in the response devices and the data section comprises a number of search characters corresponding to the number of positions addressed, - the address sections of the interrogation signals are in each case modified from one cycle to the next in such a manner that the number of the identifications positions used for the comparison increases by one unit with each cycle, starting from the first position, within each cycle, the search character located in the end position of the data section of the interrogation signals of the respective cycle is modified in each case from one interrogation signal to the next, the search character concerned passing through all values permissible for this search character, - the identification positions called up in each case by the address section of each interrogation signal are compared in the response devices with the search characters, allocated by position, of the data section of the interrogation signal concerned, - the identity signals emitted in each case by the response devices in the case of identity between the search character and identification positions compared are used for storing in the interrogation device the combination of search characters triggering the identity signal, - the combinations of search characters stored in each case during an interrogation cycle are used in the subsequent interrogation cycle for occupying the corresponding data section positions preceding the last postion of the data section of the interrogation signals of this subsequent cycle, the identity signals received during the last cycle are counted in the interrogation device.