JPS58196684A - Driving method of coil for revolving magnetic field generation - Google Patents

Abstract

PURPOSE:To prevent a transient oscillating current that is produced when the coil current is discontinued, by giving a conduction control with the prescribed timing to a desired transistor (TR) of two sets of two pairs of MOS TRs of a switching element. CONSTITUTION:A revolving magnetic field generating coil 1 is driven by a triangular wave current (a), etc. which is produced by two sets of two pairs of MOS TRs Q1/Q3 and Q2/Q4. A conduction control is given to the TR Q4, etc. among the TRs other than the TR Q1 and Q3 which conduct in opposite polarities with the self-induced voltage of the coil 1 in a period T4 immediately before the current (a) is set at (O) due to the discontinuation of driving. As a result, the current flows backward through the TRs Q4 and Q2, and the current (a) is attenuated in terms of an exponent function. Therefore the transient oscillation is produced for the current (a) during a pause period T5 and on the basis of the parasitic capacity of an MOS TR of low power consumption. This ensures a driving method of a revolving magnetic field generating coil which has reduced malfunction with low power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coil drive circuit for keeping a coil drive circuit for generating a rotating magnetic field of a magnetic bubble memory element connected, and using an M08 transistor as a switching element particularly suitable for a low power consumption drive circuit.

In conventional coil drive circuits, bipolar transistors and diodes are used as switching elements, and positive and negative DC voltages are applied to the rotating magnetic field generating coil for a certain period of time. It was carrying a current.

However, bipolar transistors have large losses due to saturation voltage and cut-off losses due to the accumulation of carriers in the base, making it difficult to create a drive circuit with low circuit loss.

A drive circuit using Mo8 transistors as switching elements has been devised to overcome this drawback, but M
o1) Since the parasitic output capacitance of the transistor is large, the coil current R causes damped oscillation when the coil current is stopped, making it impossible to stably stop the -air bubble at the normal surface position. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for driving a coil drive circuit for generating a rotating magnetic field, which achieves low circuit loss and can stably stop Km air bubbles at normal positions. and,
The present invention clarifies the generation mechanism of damped vibration that occurs when the coil current is stopped in a drive circuit using a MOS transistor as a switching element, and eliminates the cause thereof.

The following 15j of the present invention! Example f: 1st. Figures 2 and 3
This will be explained using figures. Figure 91 shows MO in the switching element.
S) It is a circuit diagram of a coil drive circuit using a transistor. The rotating magnetic field generating coil 1 is an M08 transistor Q]#
Connected to the drains of Q3 (P channel) and QCs Q4 (N channel), Mu transistor Ql#
A DC power supply is connected to the source of Q3, and the sources of the MOS transistors Q21 and Q4 are grounded. 0 1 * Cz @C3, (4 capacitors are each MOS transistor QtIQ!IQ
This is the parasitic output capacitance of 31Q4.

Figure 2 shows the coil current waveform (a
), the input signal (b) of Ql #92, and the input signal (el) of QssQa.

The reason why damped vibration occurs will be explained by referring to Figure 1 and Figure 2. During period T1, signals are input to the Ql and QzO inputs.
, Ql and Qz are electrically connected. During this period, the DC power supply 6 is connected to the coil 1 with positive polarity (the case where the coil terminal voltage EE on the side connected to the train of Qs and Q4 is higher than the other terminal voltage is positive polarity). (addition) coil current increases. Ql at T2.

Ql is non-conducting and Q31Q' is due to the diode characteristic between the drain and the substrate, which conducts in the opposite direction due to the self-induced voltage of the coil), and the coil current is pushed back by the current S and begins to decrease. The same operation is performed at T3° and T4, although the polarity is different. At T4, Q
tsQz is conductive in the opposite direction, and Q31Q4 is in a non-conductive state because there is no input sign (!).At this time, C1, C2
is almost discharged to Ov, and CB, (:4 is charged to the voltage.The moment the coil current decreases from the negative peak to O and becomes 1, QleQz becomes non-conductive.) Since Q 3 # Q a is originally non-conductive, all transistors become non-conductive. The equivalent circuit at this point is shown in the third factor. After T4kl, there is a transient phenomenon in the Misaki circuit shown in Figure @3, and the charges charged in C3 and C4 start charging CI and C2 via coil 1, respectively, so a 1111 current flows in coil 1. . Since the fill 1 also includes one minute of resistance, this vibration becomes a damped vibration as shown in Fig. 2). The oscillating current gives a disturbance to the magnetic bubble when it is stopped at a normal position, causing read/write errors in the magnetic bubble storage device, and is an inconvenience that reduces the reliability of the device. there were.

In view of this point, the present invention realizes a low consumption drive circuit.
OS) Also in a transistor drive circuit, a method for driving a rotating magnetic field generating coil is provided that prevents damped vibration when the coil current is stopped, which is a cause of read and write errors in a magnetic bubble storage device.

The coil driving method according to the present invention will be explained in detail below. During period T4, as mentioned above, Q1sQz passes through K11 in the reverse direction, and QZI and Q4 are non-conductive, so (l
, CztfOVK discharge, 03. C4 is charged with a power supply of 8Et. When the coil current during this period becomes 0, by making Q4 conductive again at 11 seconds as shown in Figure 4, the coil current flows through Q4 and conducts QZ in the opposite direction. , t8 is a damped W flow with an index m melt. In addition, (1) is the input signal of the coil wire, the input signal of Q11Q2 (!if), (c) is the input signal of Qs, (dl and Q
4 input signals. In period T5, Ql#Q3
is non-conducting and Q2tQ4 is conducting, so (
1, CB is charged to a voltage of w and discharged to C2°cnFiov. During the period T5, the coil current becomes OA and q4 becomes non-conductive, but at this point, the loop of CI and C3 including coil 1 and the loop of Cz and C4 are in a steady state, so there is no overheating phenomenon. doesn't happen. At the end of the period T5, Q4 becomes non-conductive (1IAIII1), but at this point as well, no transient current flows because it is in a fixed state as in the previous state. Therefore, according to the coil driving method according to the present invention, even if a MOll) transistor with a large parasitic output capacitance is used as a switching element KJ'f3, the damped vibration when the coil current is stopped, which causes the magnetic bubble storage device to eject or write errors, can be suppressed. Therefore, it is possible to realize a low-loss drive circuit unique to a drive circuit using an Mo8 transistor as a switching element.

Further, in this practical example, the case of a triangular wave current has been explained, but it is clear that the same effect can be obtained when a trapezoidal wave spinning current is applied.

As described above, according to the present invention, an MO with a large parasitic output capacitance
Even if B transistors are used in the drive circuit of the rotating magnetic field generating coil, they do not cause damped vibrations when the coil current stops, which can cause reading and writing errors in magnetic bubble storage devices (Mo8). 11 low loss drive circuits unique to drive circuits! There are effects that can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a coil drive circuit for generating a rotating magnetic field using an Mo8) transistor as a switching element, and Fig. 2 is a circuit diagram of a coil drive circuit for generating a rotating magnetic field using an Mo8) transistor as a switching element. A timing diagram of the input signal of Q4, Fig. 3 is an equivalent circuit of the #0 drive circuit immediately after vibration starts when the coil current stops, and Fig. 4 shows a coil drive method that can prevent coil current vibration according to the present invention. FIG. 4 is a timing diagram of input signals realized. 1...Rotating magnetic field generation coil, 2#...OP channel MOB) Rungis 'Q', 3...N channel Mo1) Ranjistor Q2.4...P channel MO
1i) Transistor qs, S...N channel MOi
l) Transistor Q4.6...DC electric key, 7,8.8
．． 10...Qx*QzaQ3+Q4 parasitic output capacitance. Figure 1, Figure 2, Figure 3, Figure 4

Claims (1)

[Claims] Using four Mo8) transistors as switching elements,
1st. the drain of the second P-channel transistor and the third . A rotating magnetic field generating coil is connected to the drain of the fourth N-channel transistor, and the $1. The source of the second transistor is connected to a DC power source, and the source of the third transistor is connected to a DC power source. In a drive circuit where the source of the fourth transistor is grounded and a triangular wave or trapezoidal wave zero current is supplied to the coil, the self-induced voltage of the skeleton coil is reversed immediately before the coil current becomes OK when the coil current stops. Two transistors conductive with polarity v
Either one of the two outer transistors is turned on i1!
** A method for driving a coil for generating a rotating magnetic field, which suppresses transient oscillating current caused by the parasitic output capacitance of the Mo1) transistor and the inductance of the coil by increasing the voltage at 1K.