Patent ID: 6429786
Filing Date: 2002-08-06
Classification: G01D,G08C

Abstract:
Sensor and evaluation system for acquiring data at a measuring point (3), especially for double sensors for detecting final positions and limit values, consisting of at least two sensors (1,1â€²,2,2â€²,16,16â€²) that are connected via a control circuit to a remotely located switching amplifier (13) with a current source or voltage source (9), whereby a connection wire (5,5â€²) leads from the current source or voltage source to the sensor (1,1â€²,2,2â€²,16,16â€²) and another connection wire (6,6â€²) leads from the sensor (1,1â€²,2,2â€²,16,16â€²) to an evaluation unit (10,10â€²), and the sensor signal of each sensor (1,1â€²,2,2â€²,16,16â€²) normally consists of a change in the current flow as compared to the current flow in the quiescent state of the sensor (1,1â€²,2,2â€²,16,16â€²) and said sensor signal is transmitted via the control circuit to the switching amplifier (13) in order to be evaluated there in an evaluation unit (10,10â€²) and to be output at an output stage (12,12â€²) in the form of signals (e.g. binary ZERO, ONE) as a function of the sensor (1,1â€²,2,2â€²,16,16â€²) and of the time, characterized by the following features:a) two sensors (1,1â€²,2,2â€²,16,16â€²)â€”a sensor pair (1â€³,2â€³16â€³)â€”are associated together with each of the two connection wires (5,5â€²,6,6â€²) to form the control circuit; b) an alternating current or alternating voltage interface (7,7â€²) is associated with each sensor pair (1â€³,2â€³16â€³), and said interface (7,7â€²) is located in the vicinity of the sensors (1,1â€²,2,2â€²,16,16â€²) and is capable of transmitting positive signals to and from one sensor (1,2,16) as well as negative signals to and from the other sensor (1â€²,2â€²,16â€²) of the sensor pair (1â€³,2â€³16â€³), whereby the two sensors (1,1â€²,2,2â€²,16,16â€²) of the sensor pair (1â€³,2â€³16â€³) are connected together antiparallel and are always operated alternately with respect to each other; c) on the basis of the polarity of the signals, the switching amplifier (13) establishes the association of the sensor signals of a sensor pair (1â€³,2â€³16â€³) that are transmitted via the same connection wires (5,5â€²,6,6â€²) to the sensor (1,1â€²,2,2â€²,16,16â€²) in question; d) the current source or voltage source (9) is a current source or voltage source with an alternating polarity.