JPS60247809A - Magnetic head driving circuit - Google Patents

Abstract

PURPOSE:To minimize fluctuations of the transient current under a nonoperating condition and a recording current, by commonly connecting the respective one end of plural magnetic heads with the connecting mid-point of a pair of common ON/OFF switching means and flowing a bipolar recording current at a prescribed timing. CONSTITUTION:Pulse train recording currents are made to flow to magnetic heads H1-H4 by changing the timing from each other. At an equivalent circuit, the series circuit of parallel capacities C1-C4 at the time of OFF is connected in parallel and the capacity C0 of a common switching means S1 or S2 at the time of OFF is connected in parallel. Since the transient current flowing to the magnetic heads under a nonoperating condition is the one produced by the movement of accumulated charges of the capacity at the time of OFF only, the fluctuation of the transient current is sharply reduced. Moreover, fluctuations of recording currents made to flow to each magnetic head H1-H4 resulting from the fluctuation of ON resistances are also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head drive circuit suitable for application to a drive circuit for a multi-channel induction thin film magnetic head.

BACKGROUND TECHNOLOGY AND PROBLEMS The multi-channel induction type thin-film magnetic head used in digital audio tape recorders has a large number of head sections piled up in a small volume, and the number of turns of the coil for each head section has its own limit. Therefore, the recording current flowing through each head portion becomes relatively large. Therefore, if you try to use the recording current by flowing it into each head at the same time,
Since the heat generation and recording current of the multi-channel magnetic head become large, and the drive circuit becomes large, in order to avoid this, the pulse train current is supplied to the coils of each head section at different timings. It is known to perform digital recording.

As mentioned above, the multi-channel inductive thin film magnetic head is
Since a large number of head sections are provided in a small volume, it is necessary to integrate the magnetic head drive circuit by reducing the number of connecting wires to the coils of each head section. As a conventional example of such a magnetic throat drive circuit, there is
A circuit as disclosed in Japanese Patent No. 84012 has been proposed. Below, with reference to FIGS. 3 to 5, a description will be given of the magnetic/somatic drive circuit jIIi. Figure 3 shows the bottom part of the multi-channel induction band thin B'A Ml air head (
The magnetic head drive circuit for the case where there are four magnetic heads will be described below (Explanation 1-1). In Fig. 3,
H+ to H4 are magnetic heads serving as head portions constituting a multi-channel magneto-type magnetic throat.

Each coil of the magnetic heel l"H+~14< is sequentially connected in series, and both ends of the series circuit and the magnetic head 'll+"
The connection midpoints of each of Ll4 are bipolar transistors, Amami effect 191-Lancester (F]):
The on-off switch consists of 11 stages of semiconductor switches such as S'rr, S'p+, S! I+
, S 51 , S 51 and S 1 are connected to one terminal (to which current is supplied, respectively), and a similar terminal 11 : & S : 2. S 'yp, S S2゜S
The other terminal to which current is supplied through ap, SF, and z is connected to ground, and 61S is a current source that supplies a constant DC current between the terminal and ground.

Then, the L-in 11 flow is phase 11.
The timing will be made light and 'C4JL will be paid.
), each on/off switch means is controlled. For example, when applying a pulse current in one direction to the magnetic navel 11 (I to 1), the on-off switch means Si1 and Si2 are turned on at the same time, and when passing a pulse current in the opposite direction, the on-off switch means S4+ and Si2 are turned on. It turns on at the same time.Also, for the magnetic heel t"+-12~H,
Similarly to the above, it is possible to apply a +E reverse direction pulse and a current to each magnetic field F H2 to H4 depending on the ON/OFF control.

) The magnetic head F'! Interest! The current of the JJ circuit +11
The equivalent circuit with S omitted is shown as shown in FIG. 4G.

Immediately, '<1 to 71 and rivers 11 to 114 are each represented by a series circuit of 11 (resistance R, and inductance 1-51 to resistance R4 and inductance The series between H4 and 1 are further connected in series and 1,
This is connected to both sides of each (+ to 114) transistor capacitor pC1 to 01 or both ends of each series circuit and the connection midpoint. People are connected between and the connection 1112.

In the equivalent circuit of FIG. ;:■ is M["("4"). Then" (in states 1 and 2, for example, a magnetic navel)", it is assumed that +1 unidirectional pulse current is applied to Ht. Then, the potential at the midpoint of the connection between the capacitor C1 and the resistor R1 rises from the initial potential, and the potential at the midpoint of the connection between the inductance l-71 and the capacitor C2 drops to approximately the ground potential, so that the capacitor @01 is charged, and the capacitor C2 is discharged.As a result, a current of 7d transiently flows to each coil of the other magnetic hexagons i' H2 to H4, and each magnetic head 82 to 144 charges its respective track. erroneous writing edges or erroneous erasures are performed on the
The level, waveform, timing, etc. of the transient current flowing through the magnetic head in the three operating states vary depending on the distance to the operating magnetic head.

Furthermore, if there are variations in the on-resistance of the on-off switch means, the recording current flowing through each magnetic node will vary accordingly.

OBJECTS OF THE INVENTION In view of the above, the present invention significantly reduces the fluctuations in the transient current flowing through the magnetic head in the non-operating state, and also reduces the on-off switching means (each magnetic field due to variation in resistance). I would like to propose a method that will reduce the intensity of the tf style.

SUMMARY OF THE INVENTION A magnetic head drive circuit according to the present invention is an electric! 17+l'
A pair of common on/off switches are connected in series between a pair of terminals to which the di current is supplied, and one end of each of the plurality of θ air heads is connected to the midpoint of the connection of the pair of common on/off switches. im, and each other end is connected to a pair of terminals through on-off switch means in separate rows, respectively, and connected to a common on-off switch 41. Controls the on/off of a plurality of pairs of on/off switch means connected to each of the magnetic heads and the plurality of magnetic heads at predetermined timing.・It is characterized by sea urchins.

According to the present invention, the part N of the transient current flowing through the magnetic helenoid 1' in the non-operating state is significantly reduced, and
On-off switch: Due to variation in on-resistance of each one? It is possible to reduce the variation in the recording current flowing through the 2r magnetic head by reducing the number of times the magnetic head is driven.

Embodiment An embodiment of the present invention will now be described with reference to FIGS. 1 and 2. Figure 1 shows Kozu in this example C4), 1:
Similar to the conventional example shown in FIG. 3, when the present invention is applied to one drive cycle of a multi-channel, i-force induction type thin film magnetic head, In some cases, for example, four magnetic heads are provided.

In FIG. 1, parts i corresponding to those in FIG. is connected to the power supply terminal (and the other end is grounded. During the connection of S+, S, and S+, let i be P.

Then, commonly connect one end of the 21 ile of 1" H4 to the connection midpoint r], and connect each other end to the 1st stage SI'1. S21. SII, SL. through the on-off switch means 5121 Sll S] 2. S42 to the ground through the on-off switch means St, S2.
, S11 to S41, and S x2'' S42 are bipolar transistors, ■ semiconductor switches such as PAET, etc. 6 Next, the operation of this 11th*l magnetic head drive Il!JJ circuit will be explained. For example, magnetic head 1
The case where a recording current is applied to 1] will be explained. Magnetism-＼
When a recording current (pulse current) in the h- direction is caused to flow through the coil at the node H+, the on/off switch means So and S2
When turning on the switches S+ and 312 at the same time and passing the recording current (pulse current) in the continuous direction, turn on the switches S+ and 312 at the same time.
J is good. In the case of this figure 1, the pulse train recording current as shown in figure 5 is different from the phase rI (to 114). to flow.

Figure 2 shows the current source I of the magnetic head drive circuit of Figure 1.
11 (resistance R1 and inductance Lx = resistance R4 and inductance 1
．． 412) 1 for one column circuit. Each magnetic node H1~H
The parallel capacitances tic+"・C4 at the time of off of the on-off and inch means connected to 1, respectively, are connected in series, and these series circuits are connected in parallel, and for this parallel circuit, the common on-off switch hand IR3+! is connected to the off state of S2. Each time the capacitance co is connected in parallel.

According to the magnetic head drive circuit of JVR, as is clear from the equivalent circuit shown in FIG. # of capacitive force when off of a pair of on-off switch means connected to a magnetic head
Since this is caused only by the movement of the electric current, the variation in the transient current flowing through the magnetic head in the non-operating state is greatly reduced.

Further, when a recording current is applied to any one of the magnetic heads 1 (1 to H4), each current is passed through an on/off switch means S.
+ or S2, the variation in the recording current flowing through each of the magnetic heads H1 to H4 due to the variation in the on-resistance of the on-off switch means is approximately 1/2 of that in the case of the drive circuit shown in FIG. 3.

(The number of magnetic heads can be any number as long as it is 211111 + C, but preferably 3 or more.

Effects of the Invention According to the present invention, variations in the transient current flowing through the magnetic head in the non-operating state are significantly reduced, and
It is possible to reduce variations in the recording current flowing through each magnetic head due to variations in the on-resistance of the on-off switch Lf&.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the magnetic head drive circuit according to the present invention, Fig. 2 is a circuit diagram with 12 equivalent circuits of Fig. 1 removed, and Fig. 3 and 1 are circuit diagrams of a conventional magnetic head drive circuit. Figure 4 is a circuit diagram similar to Figure 3, Figure 5 is a waveform diagram.H4 is a magnetic head, Sl and S2 are a pair of magnetic heads.
On-off Swisso Chiro and others, to S1+, S11 and S+2
~S42 is an on-mefuno, I-nochi means, t is a power supply terminal,
IS has 2 castors. jfl:lte i't+ru. 11(”l Figure 2

Claims (1)

[Claims] A pair of common on/off switch means are connected in series between a pair of terminals to which a power supply current is supplied, one end of each of the plurality of magnetic heads is commonly connected to a connection midpoint of the pair of common on/off switch means, and each other end is connected in series. are respectively connected to the pair of terminals through separate pairs of on/off switch means,
By controlling the on/off of the pair of common on-off switch means and the plurality of pairs of on-off switch means respectively connected to the plurality of magnetic heads, bipolar recording is performed on the plurality of magnetic heads at a predetermined timing. A magnetic head drive circuit characterized by allowing current to flow.