| 摘要 |
PURPOSE:To enable the detection of the phase of charging signals correctly at a high speed by discharging a smoothing signal with a switching element for the charged level of ink particles in respective phases detected with the shifting of the charging signal at a fixed cycle. CONSTITUTION:A phase detection signal of n phase by which ink particles are charged is detected with a sensor 8 and inputted into an analog-digital converter 24 via a smoothing circuit comprising an amplifier 12, resistors 20 and 23 of resistance values R1 and R2 respectively, a capacitor 22 of a capacitance C1 and a diode 21. When connected to the input thereof, a transistor 30 operated by a switch timing circuit 32 can minimizes a time constant C1R1 while maximizing the time constant C1R2, which will shorten the rise time of a phase discrimination signal to reduce ripples. The transistor 30 will be switched by the circuit 32 and discharged at a change of the phase, causing a falling instantaneously. In addition, the use of a value immediately before the falling as analog-digital conversion data can provide a stable data while shortening the phase detection signal by one phase thereby enabling a higher speed and a higher frequency. |
