JPS5830654B2 - Warm body warmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a write circuit (write driver) for a storage device having a magnetic head, such as a magnetic disk device.

A magnetic disk device with high recording density generally uses a write circuit as shown in FIG.

In a magnetic disk drive, the magnetic state of the recording surface changes depending on the rise time, fall time, overshoot, etc. of the write current, so these characteristics are part of the main characteristics of the write circuit.

In the circuit system shown in Figure 1, the current rise time, etc. is basically determined by the inductance of the head coil L and the damping resistance R.
It is determined by the resistance value of 1.

Although the optimum rise time for magnetic recording differs depending on the outer circumference of the recording surface and each individual head, the rise time etc. cannot be changed in the circuit shown in FIG. 1.

An object of the present invention is to obtain a write circuit whose rise time and the like are variable by changing the equivalent damping resistance.

FIGS. 2 and 3 show examples of write circuits with variable rise times and the like.

In the circuit of Fig. 2, the field effect transistor Q3 is connected to a voltage VG.
Turns on and off under control.

When the transistor Q3 is turned on, if its resistance value is r(5N), the resistance value becomes a parallel resistance of R1 and (R2+r□N), and the rise time becomes slow.

Furthermore, if the voltage (G) is continuously controlled, the rise time, etc. can be continuously controlled.

In the circuit shown in FIG. 3, control is performed by turning on and off transistors Q4 and Q5.

The operation of this circuit will be explained with reference to FIG.

First, in FIG. 3, the power supply voltage +E3. 10E4 is a resistor R3, R when transistors Q4 and Q5 are on and the transient phenomenon of the write current has ended (no spike voltage is generated due to the inductance of the head coil L when switching the current).
4. Select an appropriate voltage so that no current flows.

The operation when transistors Q4 and Q5 are off is the same as the circuit shown in FIG.

Transistor Q4. When Q5 is on, immediately after transistor Q1 is on and transistor Q2 is off, the spike voltage ■1 falls and ■2 rises, as shown in Figure 4, and the damping resistor R1 receives (■2- ■1)/R1 current ■3 flows, but at the same time diode D1 and resistor R3
on Ic3 (V2 R3) through to transistor Q4
/ R3 current flows from transistor Q5 to the resistor.

A current of Ic4=(R4Vl)/R4 flows through the diode D4.

Immediately after transistor Q1 is turned off and transistor Q2 is turned on, spike voltage (1) rises, (2) falls, and diode D2. Current Ic3 flows through resistor R3, and current Ic4 flows through resistor R4 and diode D3.

Therefore, transistor Q4. The rise time is longer than when Q5 is off.

Also ■1. ■The spike voltage in step 2 becomes smaller.

In addition, in FIG. 3, D1 to D4 + R3-R5, Q
4. If a circuit consisting of Q5 is further added, multi-stage switching becomes possible.

Since the rise time and fall time of the write current can be changed by the control signal, appropriate writing can be performed on the outer and inner circumferences of the recording surface.

Furthermore, by controlling the rise time and the like for each bit of write data, it is possible to reduce the phase shift in magnetic recording when writing onto the recording surface with the magnetic head.

Therefore, it reduces the phase shift (shift of the peak time with respect to the reference time) of the read signal of the magnetic head, and ultimately contributes to reducing the error rate of the device.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional write circuit, FIG. 2 is a circuit diagram showing one embodiment of the present invention, FIG. 3 is a circuit diagram showing another embodiment of the present invention, and FIG. 4 is a circuit diagram showing another embodiment of the present invention. 3 is a waveform diagram of each. L...Head coil, R1...Dubbing resistor, Ql, Q2...Transistor, Q3...
...field effect transistor, Q4. Q5...
...Transistor.

Claims (1)

[Claims] 1. The rise time and fall time of the write current are determined based on the inductance, the switching element connected to both ends of the inductance, and the damping resistor connected in parallel to the inductance, and the rise time and fall time of the write current according to the inner and outer circumferential surfaces of the magnetic disk. A write circuit for a magnetic head that changes the magnetic head, characterized in that a current limiting circuit is provided in series or parallel to the damping resistor, and the rise and fall times of the write current flowing through the inductance to the magnetic disk are made variable. Write circuit for head.