| 摘要 |
PURPOSE:To make quicker the response of a circuit board bias voltage to the fluctuation of the power source voltage by providing a bypassing means with the output edge in the bias generating circuit of the circuit board. CONSTITUTION:A free running oscillator 201 supplies with a driving circuit 202 an output with a square wave or the one almost similar to the wave. The circuit 202, on receiving the output, rectifies the wave form and supplies it to one end of a capacitor 203 for an AC connection. Due to the clamping action of an MIS type transistor Tr205 connected to a diode, the level of the signal at the other end of the capacitor 203 is so changed that it makes the threshold voltage VTH maximum while the TH-VCC (VCC means the power source voltage) minimum. For the negative voltage, the circuit board is saturated with electrons via the MIS type Tr204 and the board is biased negatively. Now the board bias generating voltage is once reduced in the negative direction because of the quantitative connection between power source-circuit board when the power source voltage has changed to indicate a lower voltage value, but its regular value is quickly recovered as a resistor 208 is attached to the circuit to bypassing it. |
