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Apparatus for monitoring supply of electrically conductive writing fluid in a reservoir for an ink printing device which has three electrodes with one pair of the electrodes mounted in a region of the reservoir which is constantly moistened by the writing fluid and provides a first signal which prod

Apparatus for monitoring supply of electrically conductive writing fluid in a reservoir for an ink printing device which has three electrodes with one pair of the electrodes mounted in a region of the reservoir which is constantly moistened by the writing fluid and provides a first signal which produces a fluid comparison resistance. An additional electrode together with one of the pair of electrodes produces a signal which indicates the change of resistance as a function of the fluid level of the fluid. A control electronics component receives the first and second signals and supplies an output to a shutoff device. A generator and an inverter which receives an input from the generator supply pulses to two of the electrodes.

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An apparatus for monitoring the supply of electrically conductive writing fluid (I) in a reservoir (TB) for ink printer devices comprising, three electrodes (E1, E2, E3) for resistance measurements, one pair of electrodes (E2, E3) is mounted in a region of said reservoir (TB) which is constantly moi

An apparatus for monitoring the supply of electrically conductive writing fluid (I) in a reservoir (TB) for ink printer devices comprising, three electrodes (E1, E2, E3) for resistance measurements, one pair of electrodes (E2, E3) is mounted in a region of said reservoir (TB) which is constantly moistened by said writing fluid (TI) and provides a first signal which indicates a fluid-associated comparison resistance, and a further electrode (E1) together with one of said pair of electrodes (E2, E3) provides a second signal which indicates the change of resistance therein as a function of the fluid level of said fluid (TI), a control electronics means (SE) receiving said first and second signals, a cutoff means (AV) connected to said control electronics means (SE) to indicate when the level of said writing fluid (TI) falls below a minimum level, said first and second signals is produced with DC voltage pulses produced by a generator (RG) and an inverter (I) which produces pulses (M1) and inverted pulses (M3) which have the same amplitude and said further electrode (E1) receives said DC voltage pulses (M1) and one of said pair of electrodes receives said inverted pulses (M3) which are inverted relative to said pulse (MI) and a voltage (U2) indicative of the fluid level in said reservoir (TB) occurs at the other one of said pair of electrode (E2) of said pair electrodes (E2, E3).