| 摘要 |
Device for a number of signal indicating elements and associated keys or switches, in which to each key or switch a threshold comparator (K1, K2, K3...) is allocated, the first input of which is connected to its associated key via one voltage divider each (R11/R13, R21/R23, R31/R33,...), the second input of which is connected to a first reference voltage source and the keys being connected to the summing voltage input of a latching-type comparator (DV) via one decoupling diode each (D11, D21, D31,...) and one series resistor each (R12, R22, R32,...), which are dimensioned in such a manner that the component of the voltage sum at the summing voltage input, when a key is operated, is smaller than the voltage of a second reference voltage source which is present at a second input of the latching-type comparator, that the component of the voltage sum, when a number of keys are operated, at the summing voltage input is greater than the voltage of the second reference voltage source, that the output of the latching-type comparator (DV) is connected to the second inputs of the threshold comparators (K1, K2, K3,...), in such a manner that when the voltage sum exceeds the second reference voltage, the output signal of the latching-type comparator (DV) is added to the first reference voltage and the key functions are thus not forwarded to the signal indicating elements. <IMAGE>
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