To provide a device for detecting an amount of ink for a stencil printing machine which can control, to an adequate value, radiation noise occurring in a capacitance type sensor which detects the amount of ink in an ink reservoir.
A control signal from a detection circuit 9f to an oscillator circuit 9a is turned on/off in response to a level of a clamping signal from an arithmetic processing unit 300 which is turned off during the release of a clamping plate which clamps a stencil master to be attached to a plate cylinder. When the clamping signal is turned on, the control signal is turned on, so that the oscillator circuit 9a oscillates and the amount of ink in the ink reservoir is detected. At that time the clamping plate hardly functions as an antenna for the radiation noise because the clamping plate being closed is not positioned on a propagation path of the radiation noise occurring in the oscillator circuit 9a. Meanwhile, the clamping plate 18 being released is positioned on the propagation path of the radiation noise, the clamping signal is turned off and the control signal is turned off as well. Accordingly the oscillator circuit 9a is not electrified and any radiation noise does not occur. Thus, the clamping plate 18 does not function as the antenna for the radiation noise.
Masakazu Ito
Shunichi Takahashi
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