Vdo Adolf Schindling Ag

Robert Belz

Klaus Kronenberg

Bernd Haussmann

Matthias Giron

Wolfgang Obst

A method is provided for synchronizing the counter of an electronic control device with the zero position, defined by a mechanical stop, of a pointer in an indicating instrument. The pointer is driven via a step-down gearing by a stepping motor having two windings perpendicular to each other and a two-pole rotor. The two windings are connected alternately to a source of voltage and to a measuring mechanism for determining the voltage induced in a winding not traversed by current. The pointer moves stepwise up to the mechanical stop, and the counter is set to zero in the absence of an induction. The method is substantially less expensive than prior methods. Upon an assembling of the stepping motor and the indicating instrument, a given alignment of the two-pole motor is associated with the zero position of the pointer, and the rotor is brought into this given alignment each time upon the start of the method. Thereupon the determination of the induction is effected each time only in the position of the rotor which follows this given alignment by one step.

Method of synchronization for an indicating instrument with

A method of producing an input variable for a cross-coil indicating instrument from a measurement signal is disclosed in which the frequency of the measurement signal is converted into a frequency-proportional input current for the cross-coil indicating instrument (11). Furthermore, a circuit is disclosed in which an input terminal for the measurement signal is connected to a period measuring device (3, 4, 5) the output of which is connected to a divider (6). The output of the divider feeds a control variable which is proportional to the frequency of the measurement signal (f.sub.M) to an input (13) of a processing circuit (8, 10). The known method and the known circuit have the disadvantage that, in case of a low frequency of the measurement signal, a jerky movement of the pointer of the indicating instrument (11) can be observed. In order to eliminate this jerky movement, an input current which brings the cross-coil indicating instrument 11 to a predetermined value, independent of the actual frequency, is produced below a predetermined first frequency value of the measurement signal.

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Wiesbaden, Germany

Robert Belz