| 摘要 |
PURPOSE:To simplify a circuit for forming a write signal by constituting a head driving party by connecting an active load of a flip-flop type, between a collector terminal of a pair of differential transistors of a current switch type, which have been connected both terminals of a coil and a constant-current source, and a power supply voltage terminal. CONSTITUTION:A pair of differential transistors Q1, Q2 are connected between both terminals A, B of a coil L, and a constant-current use transistor Q5 for making current flow to this coil, and they are constituted of NPN type bipolar transistors. Between a collector terminal of the transistors Q1, Q2 and a power supply voltage terminal Vcc of a circuit, transistors Q3 and Q4 being an active load are connected, and constituted of PNP bipolar transistors of a reverse conductive type. They are cross-connected to the collector terminals of the transistors Q2 and Q1 of the opposite side through plural pieces of diode trains D1-D3 and D4-D6 which have been connected in series, respectively. To base terminals of the differential transistors Q1 and Q2, a pair of complementary write signals Vin, -Vin are impressed, a head driving part is operated in the same way as a flip-flop circuit, and a direction of a current which is made to flow to the coil L is varied. |
