| 摘要 |
In such a measuring device, in order to measure the relative position of two objects the periodic scanning signals (S1, S2) obtained during scanning of the grid division (la) of a grid scale (1) by means of the grid divisions (2a, 2b) of a grid scanning plate (2) are fed to an evaluation device (W) for determining the measured values for the relative position of the two objects. At the same time, the two periodic scanning signals (S1, S2) are supplied to an error detection device (F) which transmits an error signal in the event of defective signal parameters of the two scanning signals (S1, S2). The amplitude levels of the two scanning signals (S1, S2) are each checked on both sides of their zero line in the error detection device (F) for an upper limiting value and for a lower limiting value, this checking being performed periodically in an alternating fashion. In the error-free state, the error detection device (F) supplies a periodic detection signal (ES), and in the defective state an aperiodic detection signal (Figure 1). <IMAGE>
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