JPS63253507A - Magnetic recorder and reproducing device - Google Patents

Abstract

PURPOSE:To always make stable alternating currents to flow even if the number of magnetic heads varies and, as a result, the tuning frequency of the secondary winding of a boosting transformer changes so as to stabilize the operation of a magnetic recorder and reproducing device, by installing a feedback control circuit which controls the output voltage of the secondary winding to a fixed level to each of AC signal generators which make alternating currents to flow to closely provided plural magnetic heads. CONSTITUTION:AC signal generators 2 are respectively connected with plural magnetic heads 1 which are adjacent to each other of a magnetic recorder and reproducing device and the number of the head 1 to be used can be changed. A boosting transformer 3, whose secondary winding is connected with one of the heads 1, is provided to each of the generators 2 and AC signals from an oscillator 5 are supplied to the primary winding of the transformer 3 in a state where the AC signals are superimposed upon the current of a DC power source 6 by switching the signals with a transistor (Tr) 4. A feedback control circuit 11 equipped with an integrator 13 is provided at the connecting point A of the Tr 4 and transformer 3 and the voltage of the primary winding of the transformer 3 is maintained at a fixed level by means of an output voltage Vs which is obtained by rectifying, integrating, and transducing the voltage across the connecting point A, so as to make the output voltage of the secondary voltage always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device having a plurality of G1 heads.

2. Description of the Related Art A conventional magnetic recording and reproducing apparatus of this type is constructed as shown in FIG. The second AC signal generators 2a+, 2b are configured as follows. Transistors 4a and 4b connected in series to the primary sides of step-up transformers 8a and 8b provided for each magnetic head la+lb are connected to an oscillator 5.
The output voltage of the DC power supply 6 is boosted by the step-up transformers 8a and 8b, and the inductance of the step-up transformers 8a and 8b and the magnetic head la,
lb inductance and capacitor 7a I 7
The frequency of the oscillator b is tuned to the frequency of the oscillator 5, and an alternating current is applied to the magnetic heads la and lb.

When the magnetic heads "a" and "tb" are located close to each other, when a current is applied to one magnetic head taI2, an induced current also flows to the other magnetic head Ib, and the signal recorded by the magnetic head 1b is An inconvenience arises in that part of the data is erased. Therefore, if no current is applied to one of the magnetic heads [a or tb, the first magnetic head. second control signal 8
a*sb is selectively applied to the external pressure transformer 8a.
, 8b, the transistor 25a is interposed on the primary side of the transistor 25a.
t or 25b to stop the oscillation of the oscillation circuit, and at the same time, the first. or second control signal 8a e 8b
Depending on the transistor 9a, job or 9b, L
Ob is turned off to turn off the magnetic head 1a or the closed circuit of 1a, thereby preventing the induced current from flowing.

Problems to be Solved by the Invention In such a conventional configuration, it is necessary to prevent alternating current from flowing to one of the adjacent magnetic heads 1a or 1b.
In the first case and the second case in which alternating current is passed through both magnetic heads la #tb, the inductance of the i-type head changes due to mutual induction. magnetic head ta or 1b
When the inductance changes slightly, the tuning frequency on the secondary side of the step-up transformer 8a * 8b changes, and the current flowing through the magnetic head changes between the cylindrical case and the second case, and the erasure rate changes. [changes], and the frequency characteristics of recording changed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing device in which the erasure rate and recording frequency characteristics do not change even if the number of magnetic heads used changes.

Means for Solving the Problems The magnetic recording/reproducing apparatus of the present invention connects a plurality of magnetic heads close to each other to respective separate AC signal generators,
The AC signal generating device includes a secondary winding of a step-up transformer that generates an AC signal to be applied to the magnetic heads. The present invention is characterized by the provision of a feedback control circuit that controls the output voltage to be constant regardless of the number of magnetic heads used.

According to this configuration, a feedback control circuit is provided in the AC signal generator of each magnetic head to control the output voltage of the secondary winding of the step-up transformer to a constant level, so the number of magnetic heads used in the magnetic head is reduced. Even if the inductance changes due to a change in the current, the same current can be passed through the magnetic head.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 6. Note that since the configurations of the AC signal generators respectively connected to the plurality of magnetic heads disposed close to each other are the same, one AC signal generator 2 will be described as an example.

In FIG. 1, the feedback control circuit port is constructed as follows. In other words, the primary winding of step-up transformer 8 and transistor 4
The voltage at the connection point A is half-wave rectified by the rectifier diode 12, integrated by the integrator 18 and converted to voltage vs, and the output voltage vo of the DC power supply 6 is determined based on the voltage vs. The output voltage of the primary winding of step-up transformer 8 is kept constant, the output voltage of the secondary winding of step-up transformer 8 is kept constant,
Even if the tuning frequency on the secondary side of the step-up transformer 8 changes,
The current flowing through the magnetic head 1 is kept constant.

In the embodiment shown in FIG. 1, the output voltage vo of the DC power supply 6 is controlled based on the voltage at the connection point A. The output voltage V of the DC power supply 6 is based on the terminal voltage of the resistor 14. As shown in Figure 8, the step-up transformer 3
A resistor for current detection connected in series to the magnetic head 1 as shown in FIG. The same effect can be obtained even if the feedback control circuit (2) is configured to control the output voltage vo of the DC power supply 6 based on the terminal voltage of the device 16.

In FIGS. 1 to 4 above, the voltage of the divider 18 vs.
As shown in FIG. 5, the output voltage vo of the DC power supply 6 is controlled by controlling the transistor 17 with the output of the integrator I8, controlling the base potential of the transistor 4, and controlling the secondary voltage of the step-up transformer 8. It is also possible to maintain the output voltage of the winding constant.

FIG. 6 shows another embodiment. The feedback control circuit (2) is configured as follows. A transistor 18 as a switching element is interposed between the base and emitter of the transistor 4, and a first constant voltage diode 20 is connected between the base and the tap 19 of the secondary winding of the step-up transformer 8. However, a second constant voltage diode 21 is connected between the tap 19 and the base of the transistor 18. In this case, when the negative peak voltage of the tap t9 of the step-up transformer 8 exceeds the reverse voltage of the first voltage regulator diode 20, the signal of the oscillator 5 is transmitted through the diode 22 and the secondary winding of the step-up transformer 8. grounded, transistor 4
Input to is prohibited, and transistor 4 is turned off. When the positive peak voltage exceeds the reverse voltage of the second constant voltage diode 21, current flows through the diode 28 to the transistor 18, making the transistor 18 conductive, and similarly turning off the transistor 4. Thereby, the secondary voltage of the step-up transformer 8 is controlled to be constant.

In FIGS. 1 to 4 and 6 showing each of the above embodiments, the magnetic head 1 is directly grounded, but in reality, the Swiss-Sochi circuit 24 shown in FIG. 7 is grounded. It is interposed between.

fi 4 ＾force + kft1 As described above, according to the present invention, each AC signal generating device that sends an AC current to a plurality of magnetic heads close to each other is configured to control the output voltage of the secondary winding of the step-up transformer to be constant. A feedback control circuit is provided, so even if the number of magnetic heads used changes, the inductance of the magnetic heads changes, and the tuning frequency on the secondary side of the step-up transformer changes, a stable alternating current flows through the magnetic heads. This makes it possible to maintain stable erasure rate and recording frequency characteristics even when the magnetic head used is changed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts of one embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIGS. 2 to 6 are block diagrams of other embodiments, respectively.
FIG. 7 is a block diagram of a conventional magnetic recording/reproducing device. DESCRIPTION OF SYMBOLS 1...Magnetic head, 2...AC signal generator, 8.
...Step-up transformer, 4°...Transistor [switching transistor] i6...DC power supply, Kame 1°...Feedback control circuit, 12...Rectifier diode, 13...Cost divider, 14.16...・Resistor for current detection, 20.
21... 1st. Second voltage regulator diode.

Claims (1)

[Scope of Claims] 1. A separate AC signal generator is connected to each of a plurality of magnetic heads close to each other, and the number of magnetic heads used is switched by flowing AC current among the magnetic heads. Additionally, the AC signal generator is provided with a feedback control circuit that controls the output voltage of the secondary winding of the step-up transformer that generates the AC signal to be applied to the magnetic heads to be constant regardless of the number of magnetic heads used. magnetic recording and reproducing device. 2. An AC signal generator is connected to a DC power source by connecting the primary winding of a step-up transformer and a switching transistor in series, and the DC power source is connected so that the terminal voltage at the connection point between the transistor and the primary winding is constant. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic recording and reproducing apparatus is configured to control the output voltage of the switching transistor or the base potential of the switching transistor. 3. The AC signal generator is connected to a DC power source by connecting the primary winding of a step-up transformer, a switching transistor, and a current detection resistor in series, and 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic recording and reproducing apparatus is configured to control the output voltage of a DC power supply or the base potential of the switching transistor. 4. Connect the AC signal generator to a DC power source by connecting the primary winding of the step-up transformer and the switching transistor in series, and adjust the output of the DC power source so that the divided voltage of the secondary winding of the step-up transformer is constant. 2. The magnetic recording/reproducing device according to claim 1, wherein the magnetic recording/reproducing device is configured to control a voltage or a base potential of the switching transistor. 5. The AC signal generator is connected to a DC power source by connecting the primary winding of a step-up transformer and a switching transistor in series, and a current detection resistor is connected in series between the secondary winding of the step-up transformer and the magnetic head. Claim 1 characterized in that the output voltage of the DC power supply or the base potential of the switching transistor is controlled so that the terminal voltage of the current detection resistor is constant.
The magnetic recording and reproducing device described in . 6. An AC signal generator is connected to a DC power supply by connecting the primary winding of a step-up transformer and a switching transistor in series, and connects the control terminal of a switching element interposed between the base and emitter of the switching transistor to the step-up transformer. A first constant voltage diode is connected between the connection point of the secondary winding of the transformer, and a second constant voltage diode is connected between the connection point and the base of the switching transistor. A magnetic recording and reproducing device according to claim 1.