JP2595032B2 - Magnetic recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device that supplies a pulse current to a two-terminal recording head, and more particularly to a magnetic recording device that can easily connect a recording head to a circuit. .

[Conventional technology]

A drive circuit for a recording current of a conventional magnetic recording apparatus is provided with a pulse current by connecting both ends of a two-terminal recording head to a current driver as described in JP-A-61-11905. There was something as shown.

In this manner, when supplying pulsed current in the positive direction of the recording head 6 current I _W is closes the Yotsute switch S _{1, 4} to Arajime gate signals G _{1, 4,} gate signal G _{2, 3} Switches S ₂ and S ₃ are opened by the
Close Yotsute switch S ₅ to G _{5, 6,} so that at the same time open the switch S _6. That this shall current of the constant current source I _S is supplied as a pulse current flowing in only the recording head 6 while closing the S _5.

In this drive circuit, the current of the current source I _S is supplied substantially directly recorded head, advantage that the accuracy of the pulse current value is high has been made.

[Problems to be solved by the invention]

However, in the above-described conventional art, the number of switches is as large as six, which complicates the configuration of the drive circuit. Both terminals of the recording head must be connected to the drive circuit. When trying to implement multiple tracks, it became difficult.

An object of the present invention is to supply a pulse current to a recording head with a drive circuit having a simple circuit configuration, and to make it possible to connect one end of the recording head to a voltage source, thereby facilitating drawing out of a terminal of the recording head. Is to do.

[Means for solving the problem]

Above object, the circuit diagram of FIG. 1, and the second gives the variation of the constant potential at the timing for supplying the pulse current I _W as shown in the timing Chiya over bets Figure example, the output voltage V of the voltage driver 1 such as TTL _o Capacitor 2 and resistor 3
Connected to one terminal of the recording head 6 through a, it is achieved by connecting the other terminal of the recording head to a constant voltage source V _E.

[Action]

Capacitor 2 operates to differentiate the output voltage V _o of the voltage driver 1. I connexion recording current I _W to this, the negative direction of the pulse current at the time of changing the pulse current of a positive direction, the V _o2 reversed V _o1 when the output voltage V _o is changed from V _o1 to V _o2 .

At this time, assuming that the relationship between the capacitance C of the capacitor 2 and the resistance value R of the resistor 3 is a resistance component R _H and an inductance component L _H of the recording head, C = 4L _H / (R + R _H ) ² . . By doing so, the recording current I _W is such that the rise time _Tr is minimized as shown in FIG. Becomes Where V is the change the width of the potential of _{V o (V o2 -V o1)} . The maximum value I _WMAX of I _W (t) at this time is The pulse current width T _pw at 0.5 × I _WMAX is given by T _pw ≒ 5 · L _H / (R + R _H ) (3)

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

Input signal V _i removes the DC component, a capacitor 11 and a bias voltage source for supplying a bias current to the NPN transistor
Via a resistor connected 12 to V _B, it is input to the base terminal of the NPN transistor 13 constituting the Emitsutahorowa.
The collector terminal of the transistor 13 is connected to the constant voltage source V _CC, emitter terminals via a constant current source I _S constant voltage source V _EE
It is output as the output voltage V _o of the voltage driver 1 is connected to. The voltage V _o is configured to be inputted to the other terminal of the recording head 6 having one end grounded via a series circuit of a capacitor 2 and resistor 3.

Through a step-shaped voltage change of Emitsutahorowa the input signal V _i, are output at substantially the same voltage change V _o, supplies a pulse current I _W of the formula (1) to the recording head 6.
At this time, the magnitude of the constant current source I _S is set larger than I _WMAX.

This embodiment is suitable for a relatively small current recording current driving method in which the magnitude of the pulse current is several tens mA _{o_p} , and the circuit configuration is simple. Moreover, since the active element can be realized only by the NPN transistor, high-speed voltage driving is easy, and a pulse current of several ns can be supplied.

Specifically, the resistance component of the head R _H = 20Ω, the inductance component L _H = 5 μH, and the pulse current width I T of T _pw = 50 ns.
_When supplying a current of _WMAX = 20 mA _{o_p} , from equation (3), R _H
+ R = 500Ω, so R = 480Ω, from which C = 40nF,
Also, V = 13.5V is obtained from equation (2).

 A second embodiment of the present invention will be described with reference to FIG.

The configuration of the present embodiment will be described below. The input signal V _i is V _i
Are connected to the base terminals of an NPN transistor 131 and a PNP transistor 132, respectively, to which emitter terminals are connected via capacitors 111 and 112 for removing the DC component. The base terminal of the transistor 131 is connected to the constant voltage source V _CC through a resistor 141, is connected to the anode terminal of the diode 121. The base terminal of the transistor 132 is
Connected to a constant voltage source V _EE via a resistor 142,
The diode 122 is connected to the cathode terminal thereof, and the anode terminal of the diode 122 is connected to the diode 127 described above.
Connected to the cathode. The collector terminals of the transistors 131 and 132 are connected to constant voltage sources V _CC and V _EE , respectively. Such a circuit in a connected relationship with the voltage driver 1 such, taking the connecting point connecting the respective emitter terminals of the output V _o Torajisuta 131 and 132. This voltage V _o, the capacitor 2
This is configured to be input to the other terminal of the recording head 6 having one end grounded via a series circuit of the resistor 3 and the resistor 3.

Step-like change in voltage of the input signal V _i is resistor 141,14
2. A bias voltage is added to the base terminals of the transistors 131 and 132 via a bias circuit composed of the diodes 121 and 122, and is input. Voltage change was although connexion V _i is output at substantially the same voltage change V _o, supplies a pulse current I _W of the formula (1) to the recording head 6.

This embodiment is suitable for a recording current drive of a relatively large current having a pulse current of several hundred _{Ao_p} .

According to the present embodiment, the current supply from the constant voltage sources V _CC and V _EE can be set to almost the pulse current supplied to the recording head, and a reduction in power consumption of the voltage driver can be expected.

 A third embodiment of the present invention will be described with reference to FIG.

This embodiment is a circuit for supplying a pulse current to a multi-head device. The input signals _{Vi1 to Vi} are respectively input to the voltage drivers D1 _{to Dn as} described in the above embodiment. These outputs _Vo1-n are respectively connected to capacitors C
It is connected to the input terminal of the multi-conductor cable 7 via a series circuit consisting of 1 _{to n} and resistors R 1 to _n . Further, the output terminal of the cable 7 is connected to the input terminals of the recording head elements H1 _to Hn in which one end of the multihead 60 is shared. The common terminal 8 of the multihead 60 is connected to the ground terminal of the voltage driver via the conductor of the cable.

In response to the step-like voltage changes of the input signals _Vi1 to _n , the voltage drivers D1 to _n output the voltages _Vo1 to _n , and supply the pulse currents to the recording _{heads H1} to _{Hn according} to the above equation (1). I do.

According to the present embodiment, the multi-head 60 having one end shared
Can be adopted, and the number of terminals of the multihead 60 and the number of conductors of the cable can be set to n + 1 of the number n of heads, so that the multihead can be easily formed. In addition, each voltage driver D
_By changing the timings at which the pulse voltages are supplied by changing the output voltages V _{o1 to n} of the multi-head 60, the current capacity of the conductor connected to the common terminal 8 of the multi-head 60 and the voltage driver D 1 to _n There is also an effect that the current capacities of the constant voltage sources V _CC and V _EE can be reduced.

〔The invention's effect〕

According to the present invention, a pulse current can be supplied to a recording head by a driving circuit using a voltage driver having a simple circuit configuration, and one terminal of the recording head can be connected to a voltage source, so that the terminal of the recording head can be easily pulled out. .

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing the principle configuration of the present invention, and FIG.
FIG. 3 is a timing chart showing the operation of FIG. 1, FIG. 3 is a detailed view of a pulse current waveform according to the present invention, and FIGS.
FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 7 is a circuit diagram showing a conventional recording current drive circuit. 1 ...... voltage driver, 2 ...... capacitors, 3 ...... resistor, the resistance component of the 4 ...... recording head, the inductance component of the 5 ...... recording head, 6 ...... recording head, I _W ...... recording current, V _i …… Input signal, V _o …… Voltage driver output.

Claims (1)

(57) [Claims] 1. A magnetic recording apparatus for supplying a pulse-like recording current to a two-terminal recording head, a voltage driver whose potential changes by a fixed amount when driving the pulse current, and a two-terminal one terminal connected to a constant voltage source at one end. In a magnetic recording apparatus in which a recording head, the voltage driver and the other terminal of the recording head are connected by a series circuit of a capacitor and a resistor, the capacitance C of the capacitor
And the resistance component of the recording head,
Assuming that R _H and the inductance component are L _H , C = 4L _H / (R +
R _H ) ² .