JPH0816963B2 - Recording / playback amplifier for 2-terminal magnetic head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a recording / reproducing amplifier for a magnetic head, and particularly to a technique effectively applied to a recording / reproducing amplification technique of a two-terminal magnetic head.

[Conventional technology]

A magnetic head is generally known as a means for recording / reproducing information on / from a magnetic surface recording medium.

For example, in a magnetic disk device that uses a magnetic disk, which is a type of magnetic surface recording medium, as a recording medium, a two-terminal thin film magnetic head and a recording / reproducing amplifier for a two-terminal thin film magnetic head are used as one means for achieving high recording density. It has come to be used.

That is, it is known that the two-terminal thin film magnetic head is suitable for achieving a high recording density as compared with the three-terminal monolithic magnetic head having a center tap using ferrite before that. Is small.

Therefore, in a read / write amplifier for a two-terminal thin film magnetic head, the head impedance noise generated by the inductance of the head and the input capacitance and input impedance of the read amplifier during reproduction is within the reproduction band as compared with a monolithic ferrite head. Therefore, the damping resistance element, which is indispensable in the case of the ferrite head and has a relatively small value for reducing the head impedance, which is connected between the head terminals, is unnecessary.

On the other hand, the two-terminal thin-film magnetic head has a drawback that the direct current resistance value is larger than that of a monolithic type ferrite head, and in particular, in order to achieve high density recording, the head is used to compensate for the decreasing S / N ratio. When the number of turns of the coil pattern is increased, the DC resistance value increases as the number of turns increases.

For example, in a two-terminal thin film magnetic head generally used at present, it is said that the DC resistance value is about 25 to 30Ω when the number of turns is 30.

Thus, when the DC resistance value of the head becomes higher than a certain level, the reproduction output generated between the head terminals at the time of reproduction due to the combined resistance value of the head resistance, the input impedance of the reproduction amplifier and the damping resistance connected between the heads. Is divided, and the effect that the input to the regenerative amplifier becomes smaller by that amount cannot be ignored. For this reason, the value of the damping resistance connected between the heads cannot be reduced below a certain level.

On the other hand, when the two-terminal thin film magnetic head is driven by a recording amplifier, for example, when the value of the recording current applied to the head is changed for the purpose of a characteristic test of the recording medium or the head itself or other purposes, the recording current waveform is over-exposed. There is a problem that the shoot changes greatly and deviates from the optimum current waveform.

For optimizing the recording current, for example,
As described in 1-25130, the switch for switching the current value and the digital / analog converter for converting the set value into an analog value are connected to the current supply section of the head driving transistor to set the switch. It is conceivable to make the current value of the drive transistor variable depending on the value to avoid the overshoot of the waveform of the recording current regardless of the change of the recording current amount.

[Problems to be Solved by the Invention]

However, in the related art, although some effects can be obtained in optimizing the recording current waveform,
No mention is made of measures against the above-mentioned decrease in reproduction output due to increase in resistance of the terminal thin-film magnetic head, and it is not possible to achieve both optimization of the recording current waveform and prevention of decrease in reproduction output due to increase in resistance. There is a problem.

Further, in the above-mentioned conventional technique, a complicated and expensive circuit element such as a digital / analog converter or a switch is required for optimizing the recording current waveform, which causes a problem that the circuit is complicated and the scale is increased.

Therefore, an object of the present invention is to optimize the recording current waveform,
It is an object of the present invention to provide a recording / reproducing amplifier for a magnetic head, which can achieve both prevention of reduction in reproduction output during reproduction.

Another object of the present invention is to provide a recording / reproducing amplifier for a two-terminal magnetic head capable of realizing reduction of manufacturing cost and improvement of operation reliability.

Still another object of the present invention is to provide a recording / reproducing amplifier for a two-terminal magnetic head which can easily cope with an improvement in recording density on the magnetic recording medium side.

The above and other objects and novel features of the present invention are as follows.
It will be apparent from the description of this specification and the accompanying drawings.

[Means for solving the problem]

The outline of a typical invention disclosed in the present application is briefly described as follows.

That is, the recording / reproducing amplifier for a two-terminal magnetic head according to the present invention includes a recording amplification section for supplying a recording current to the two-terminal magnetic head and a signal level conversion section for supplying a signal corresponding to information to be recorded to the recording amplification section. A recording / reproducing amplifier for a two-terminal magnetic head, comprising: a reproducing amplifier for amplifying a signal reproduced by the two-terminal magnetic head; and a reference voltage source connected to the terminal of the two-terminal magnetic head and the recording amplifier. A first damping unit including a resistance element interposed between the first damping unit, a switch unit that operates at the time of recording, and a resistance element connected in series to the switch unit, and two terminals in parallel with the first damping unit. The recording amplifier includes a second damping unit interposed between a terminal of the magnetic head and a reference voltage source connected to the recording amplifier, and the emitter of the recording amplifier contacts the two-terminal magnetic head. First and second transistors constituting the upper portion is connected the collector side to the reference voltage source is, collector side 2
A third transistor and a fourth transistor which are connected to the terminal magnetic head and constitute a lower stage portion, the first transistor of the upper stage portion and the fourth transistor of the lower stage portion, and the second transistor of the upper stage portion and the lower stage portion. The third transistors are each set as a set, and each set is alternately turned on / off repeatedly to perform an operation of alternately inverting the recording current flowing through the two-terminal magnetic head.

[Action]

In the recording / reproducing amplifier for a two-terminal magnetic head according to the present invention, the resistance element forming the first damping means is used during reproduction. That is, the first damping means is connected in parallel with the regenerative amplifier to form a combined resistance. By the way, as described above, when the head resistance value is large enough to be ignored with respect to the combined resistance by increasing the number of turns of the coil pattern of the thin film magnetic head for the purpose of realizing high density recording, The reproduction output generated at both ends of the head is divided between the head resistance and the combined resistance, and the output input to the reproduction amplifier is reduced accordingly. Therefore, from this viewpoint, the resistance value of the first damping means is large. Is desirable.

On the other hand, from the viewpoint of reducing the head impedance, the input capacitance of the reproduction amplifier, and the head impedance noise caused by the combined resistance, it is desirable that the combined resistance be small. Therefore, the optimum resistance value of the first damping means is determined where the best S / N ratio is obtained from the balance between the reproduction output value after the voltage division and the head impedance noise value. The resistance value of the damping means is several kΩ.

In addition, the second damping device provided in parallel with the first damping device.
The damping means has, for example, a configuration in which a switching means such as a diode whose anode side is connected to a recording voltage source and a resistance element are connected in series. For example, as shown in Examples described later, a recording amplification section Are connected in parallel between the collector and the emitter of the transistor constituting the.

Therefore, at the time of recording, the voltage drop due to the V _BE (base-emitter voltage) of the transistor that constitutes the recording amplification section becomes equal to the voltage drop at the diode that is the switching means, and is connected in series with the diode. This is equivalent to a resistive element being connected in parallel to the head. Therefore, the second damping means acts as a damping resistance during recording, and the recording current waveform can be optimized by setting the resistance value of the second damping means to a desired value. For example, in order to set the amount of overshoot of the recording current waveform to about 10%, the resistance value of the second damping means is about several hundred Ω.

This means that the optimum values of the damping means are different during reproduction and during recording, which cannot be achieved simply by providing a single damping as in the conventional case.

However, in the case of the present invention, the second damping means does not function as damping during reproduction due to the action of the switch means, so that different damping values can be realized during recording and during reproduction.

In other words, the playback output that occurs in the head during playback is usually a few hundred μV _PP (the peak-to-peak value of the waveform), which is sufficiently small, while the operating voltage of the diode is usually 800 mV, which is much higher. Sometimes the diode is O
Because it does not N.

Further, by adding a capacitive element such as a capacitor as a constituent element of the second damping means, the capacitor has a property of passing only direct current and not passing current. Therefore, the damping effect of the second damping means is obtained. Can be enabled only when the recording current applied to the head is reversed.

Therefore, according to the recording / reproducing amplifier for a two-terminal magnetic head of the present invention, it is possible to achieve both the optimization of the recording current waveform at the time of recording and the prevention of the reduction of the reproducing output at the time of reproducing.

Further, in the case of the present invention, since, for example, only a small number of diodes and resistance elements are used, there is no need for complicated and expensive circuit elements such as switches and digital-analog converters unlike the conventional case, and The cost can be reduced and the reliability of operation can be improved.

Further, as the recording density on the magnetic recording medium side increases, the magnetic energy that holds unit information decreases, and in order to reproduce information, the number of winding patterns in the thin-film magnetic head is increased to increase the magnetic energy. However, in the case of the present invention, it is possible to realize an increase in the number of turns without worrying about an increase in the DC resistance value. It is possible to easily cope with an increase in recording density.

Example 1 An example of a recording / reproducing amplifier for a two-terminal magnetic head according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram schematically showing an example of the configuration of a recording / reproducing amplifier for a two-terminal magnetic head which is an embodiment of the present invention.

Recording amplifier 1 connected to 2-terminal thin film magnetic head 2
Is a transistor 101 (first transistor) and a transistor 102 (second transistor) whose emitter side is connected to the two-terminal thin-film magnetic head 2 and whose collector side is connected to an arbitrary reference voltage source V ₁ to form an upper stage portion. And a transistor 103 (third transistor) and a transistor 104 (fourth transistor) whose collector side is connected to the two-terminal thin-film magnetic head 2 and constitutes the lower stage portion.

Then, the upper-stage transistor 101 and the lower-stage transistor 104, and the upper-stage transistor 102 and the lower-stage transistor 103 form a group, and the groups alternately repeat ON / OFF, whereby a two-terminal thin-film magnetic head is produced. The recording current flowing in 2 is alternately inverted.

Resistors 105 and 106 are connected to the base sides of the transistors 103 and 104 that form the lower stage, and the transistors 103 and 104 corresponding to changes in the base potential of the transistors 103 and 104 are connected.
By delaying the ON / OFF operation, the inversion time of the two-terminal thin film magnetic head 2 is matched.

A current source 11 is connected via a switch 14 to the emitter sides of the transistors 103 and 104 that form the lower stage, and supplies a current I ₂ to the recording amplifier 1.

Reference numeral 3 is an upper-stage transistor 10 that constitutes the recording amplifier 1.
An upper recording level converter that drives 1 and 102,
A plurality of resistors 109 and 110 and a plurality of transistors 10
7 and transistor 108.

Transistor 10 that constitutes the upper recording level converter 3
A current source 10 is connected to the emitter sides of 7 and 108 via a switch 13, and the upper recording level converter 3 is connected.
The current I ₁ is supplied to.

The lower signal level converter 7 is connected to the base side of the lower transistors 103 and 104 of the recording amplifier 1 via the resistors 105 and 106.

The lower signal level converter 7 and the upper recording level converter 3 are digital recording signals coming from the outside.
It is connected in parallel to a first recording level converter 6 which counts down 201 by a flip-flop or the like and converts it into a recording signal 202 and a recording signal 203 having opposite phases.

The signal level converter 7 for the lower stage is based on the recording signal 202 and the recording signal 203 input from the first recording level converter 6, and the transistors 101 and 102 in the upper stage of the recording amplifier 1 are used.
The recording signal 204 and the recording signal 205, which are in opposite phase to each other at a level lower than the base potential of, are generated and given to the transistors 103 and 104 on the lower stage side.

An example of the relationship between the recording signals 201 to 205 and the recording current applied to the two-terminal thin film magnetic head 2 is shown in FIG.

On the other hand, the two-terminal thin film magnetic head is connected to a reproduction amplifier 8 for performing first stage amplification of a reproduction output waveform generated between the terminals of the two-terminal thin film magnetic head 2.

The regenerative amplifier 8 includes a transistor 117 and a transistor 118 for first-stage amplification whose base side is connected to each terminal of the two-terminal thin-film magnetic head 2, and this transistor.
The transistors 123 and 124 for cascade connection have emitters connected to the collector sides of 117 and 118, respectively, and a plurality of load resistors 125 and 126 provided on the collector sides of the transistors 123 and 124.

In this way, the cascade connection makes it possible to prevent the occurrence of so-called mirror capacitance, which appears when the input capacitance of the regenerative amplifier 8 is multiplied by the gain of the regenerative amplifier 8, to reduce noise.

A voltage source + V ₂ and a voltage source + V ₃ are connected to the base side and the collector side of the transistors 123 and 124, and give an operating voltage of an arbitrary level.

A current source 12 is connected to the emitters of the transistors 117 and 118 for first-stage amplification via a switch 15 that is turned on during reproduction, and supplies a current I ₃ .

The regenerative amplifier 8 is connected to an amplifier 9 which receives the regenerated output obtained on the collector side of the transistors 123 and 124 constituting the regenerative amplifier 8 and further amplifies the latter stage. It is outputting.

A first damping 4 including a plurality of resistors 111 and 112 is provided between the terminal of the two-terminal thin film magnetic head 2 and the reference voltage source V ₁ .

That is, the plurality of resistors 11 forming the first damping 4
1 and 112 are 2-terminal thin film magnetic heads 2 during reproduction.
Of the transistors 117 and 118 constituting the regenerative amplifier 8, and at the same time, it acts as a damping resistance of

Here, as shown in FIG. 3, the head impedance is the inductance L of the two-terminal thin-film magnetic head 2 that causes a differential between the terminals of the two-terminal thin-film magnetic head 2.
The differential input capacitance of the regenerative amplifier 8 and the total capacitance C of the differential stray capacitance between the terminals of the two-terminal thin-film magnetic head 2;
With respect to the damping 4, it is caused by L, C, R, which becomes the differential resistance value R of the regenerative amplifier 8 connected in parallel with the resistors 111 and 112 that form the first damping 4.

At this time, assuming that the input impedances of L and C and the regenerative amplifier 8 are constant, the resistance of the first damping 4 11
By reducing 1 and 112, it is possible to reduce the head impedance in the reproduction band, as shown in FIG.

By the way, as shown in FIG. 4, a reproduction output generated between the terminals of the two-terminal thin-film magnetic head 2 by the voltage division by the above-mentioned differential resistance value R and the resistance value of the two-terminal thin-film magnetic head 2 is generated. In order to minimize this decrease in playback output,
As shown in the figure, it is necessary to increase the resistance value of the first damping 4.

In other words, it is the first to suppress the head impedance and prevent the reproduction output from decreasing to obtain the best S / N ratio.
There is an optimum value for the resistance 111 and the resistance 112 of the damping 4, which is generally a value of several kΩ.

In the case of this embodiment, a diode 115 is further provided between each terminal of the two-terminal thin-film magnetic head 2 and the reference voltage source V ₁ , for example, a plurality of resistors 113 and resistors 114 each having a resistance of several hundred Ω.
The second damping 5 configured by connecting the (switch means) and the diode 116 (switch means) in series,
It is provided in parallel with the first damping 4.

In the second damping 5, the anode sides of the diodes 115 and 116 are connected to the reference voltage source V ₁ , and
Resistors 113 and 114 in series with the diodes 115 and 116
Is connected to the terminals of the two-terminal thin film magnetic head 2, and functions as damping only during recording as described later.

Hereinafter, an example of the operation of the recording / reproducing amplifier for the two-terminal magnetic head of this embodiment will be described.

First, at the time of recording, the transistor of the recording amplifier 1
The operation when the pair of the transistor 102 and the transistor 103 is ON will be described.
Of course, the opposite set of transistor 101 and transistor 104 is ON
It goes without saying that the same is true for the case.

Now, when the transistor 102 is ON, in the upper recording level converter 3, the transistor 107 is ON and the transistor 108 is OFF. At this time, the base level of the transistor 102 is the reference voltage if the base current is ignored. Source V ₁
It becomes the same level as the electric potential (hereinafter referred to as V ₁ ) of.

On the other hand, the base of the transistor 101 than the potential of the reference voltage source V _1, a voltage drop below the level by the resistor 109 and the current I _1. Therefore, the emitter potential of the transistor 102 is at a level lower than V ₁ by 1V _BE .
Therefore, no current flows through the resistor 113 of the second damping 5 connected to the emitter of the transistor 102. this is,
This is because the level on the cathode side of the diode 115 connected in series with the resistor 113 is 1 V _BE lower than V ₁ .

On the other hand, in the second damping 5, the transistor 101
In the case of the resistor 114 and the diode 116 connected to the emitter side of the transistor 116, the transistor 102 and the two-terminal thin film magnetic head 2 are connected in parallel between the reference voltage source V ₁ and the emitter of the transistor 101. Is turned on, and the emitter of the transistor 102 and the cathode side of the diode 116 have the same potential. Therefore, the recording current I ₂ is divided into the two-terminal thin film magnetic head 2 and the resistor 114.

This is equivalent to the resistor 114 becoming a damping resistor connected between both terminals of the two-terminal thin film magnetic head 2.

Therefore, by arbitrarily changing the resistance value of the resistor 114, it is possible to suppress the overshoot amount and adjust the recording current waveform to be optimum as shown in FIG.

For example, in the case of a thin film magnetic head having a winding pattern with 30 turns, an optimum write current waveform can be obtained by setting the value of the resistor 114 to about several hundreds Ω.

At this time, the resistances 111 and 1 of the first damping 4 are
Although a current also flows through 12, the contribution to the damping effect is small because the resistance value is as large as several kΩ as described above.

On the other hand, at the time of reproduction, the level of the reproduced waveform generated between the terminals of the two-terminal thin film magnetic head 2 is at most several hundreds μV _pp ,
Since the potential difference of about 800 mV required for turning on the diodes 115 and 116 is much smaller, the diodes 115 and 116 do not turn on.

For this reason, no current flows through the resistors 113 and 114 during reproduction, the second damping 5 does not act as damping during reproduction, and it is possible to prevent a reduction in reproduction output due to partial pressure on the damping resistance side.

As described above, according to the recording / reproducing amplifier for the two-terminal magnetic head of the present embodiment, the first damping 4 and the second damping 5 perform the proper damping action at the time of reproducing and at the time of recording, respectively. The optimum S / N ratio can be obtained by appropriately setting the values of the resistors 111 and 112 forming the damping 4, and the resistors 113 and 1 forming the second damping 5 can be used at the time of recording.
By appropriately setting the value of 14, it is possible to optimize the recording current waveform, and it is possible to achieve both noise reduction during reproduction and prevention of reduction in reproduction output and optimization of the recording current waveform during recording. Become.

As a result, the recording density is increased on the magnetic recording medium side (magnetic energy for holding unit information without concern about a decrease in reproduction output due to an increase in DC resistance value accompanying an increase in the number of turns in the two-terminal thin film magnetic head 2). The increase in the number of turns in the two-terminal thin film magnetic head 2 can be realized, and a higher recording density in the magnetic recording medium can be achieved.

Further, in the regenerative amplifier 8, a plurality of transistors
With the configuration in which the 123 and 124 and the transistors 117 and 118 are connected in cascade, the input capacitance in the regenerative amplifier 8 can be reduced, which contributes to noise reduction and a plurality of sets of transistors corresponding to each of the plurality of two-terminal thin film magnetic heads 2. 117 and 118 through transistor 123
And by connecting in parallel to the emitter side of 124,
A channel (head) select configuration can be easily realized.

In addition, the first damping 4 and the second damping 5 are
Since it is composed of a small number of resistance elements and simple circuit elements such as diodes, it is not necessary to use complicated circuit parts such as digital-analog converters, reducing manufacturing costs and improving operation reliability. can do.

[Embodiment 2] FIG. 6 is a circuit diagram showing a main part of a recording / reproducing amplifier for a two-terminal magnetic head according to another embodiment of the present invention.

In the case of the second embodiment, the second damping 5A corresponding to the second damping 5 in the first embodiment is provided with a plurality of diodes 115a and a diode 116a, a plurality of resistors 113a and 114a, and a plurality of capacitors 121 and By configuring the capacitors 122 to be connected in series, the second damping 5A acts only when the recording current is reversed.

That is, by utilizing the property that the capacitors 121 and 122 block the DC component and pass only the AC component, for example, the capacitance of the capacitors 121 and 122 is made equal to that of a bus capacitor that transmits the frequency of the recording / reproducing signal. By doing so, it is possible to perform an appropriate damping action at the time of reversal at which the overshoot of the recording current becomes maximum, and for example, by appropriately selecting the combination of the capacitance of the capacitors 121 and 122 and the resistors 113a and 114,
The recording current waveform can be adjusted more optimally.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Nor.

For example, the switch means constituting the second damping means is not limited to the diode as exemplified in each of the above embodiments, but may be, for example, a MOS-FET, an analog switch, a Zener diode or the like.

〔The invention's effect〕

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, according to the recording / reproducing amplifier for a two-terminal magnetic head according to the present invention, a recording amplifying section for supplying a recording current to the two-terminal magnetic head and a signal for supplying a signal corresponding to information to be recorded to the recording amplifying section. A recording / reproducing amplifier for a two-terminal magnetic head, comprising a level converting section and a reproducing / amplifying section for amplifying a signal reproduced by the two-terminal magnetic head, the terminal being connected to the terminal of the two-terminal magnetic head and the recording / amplifying section. The first damping means, which comprises a resistance element interposed between the reference voltage source and a switching element, a switching means that operates during recording, and a resistance element that is connected in series to the switching means. And a second damping unit interposed in parallel between a terminal of the two-terminal magnetic head and a reference voltage source connected to the recording amplification unit. Includes first and second transistors having an emitter side connected to the two-terminal magnetic head and a collector side connected to the reference voltage source to form an upper stage section, and a collector side connected to the two-terminal magnetic head for a lower stage section. A third transistor and a fourth transistor constituting the first stage transistor, an upper stage first transistor and a lower stage fourth transistor, and an upper stage second transistor and a lower stage third transistor. Each group becomes a group, and each group alternately repeats ON / OFF.
Since the recording current flowing through the terminal magnetic head is alternately inverted, the resistance value of the resistance element in each of the first damping means and the second damping means is appropriately set, so that the recording and reproducing operations are performed. Thus, it is possible to realize the optimum damping characteristic, and it is possible to achieve both the optimization of the recording current waveform and the prevention of the reduction of the reproduction output during reproduction.

Moreover, since only a small number of resistance elements and simple circuit elements such as diodes or capacitors are used, complicated components such as a digital-analog converter are not required, which reduces manufacturing costs and improves operation reliability. Can be realized.

Furthermore, the sensitivity of detecting magnetic energy can be improved by increasing the number of turns of the winding pattern forming the two-terminal magnetic head without fear of adverse effects due to increase in DC resistance. It is possible to easily cope with the increase in the recording density.

[Brief description of drawings]

FIG. 1 is a circuit diagram schematically showing an example of the configuration of a recording / reproducing amplifier for a two-terminal magnetic head, which is an embodiment of the present invention, and FIG. 2 is a recording signal and a signal applied to a two-terminal thin film magnetic head. FIG. 3 is a diagram showing an example of the characteristics of a recording amplifier for a two-terminal thin film magnetic head, and FIG. 4 is a recording amplifier for a two-terminal thin film magnetic head. 5 is a diagram for explaining an example of the characteristics of FIG. 5, FIG. 5 is a diagram showing an example of the operation of the recording / reproducing amplifier for a two-terminal magnetic head according to one embodiment of the present invention, and FIG. FIG. 6 is a circuit diagram showing an example of a main part of a recording / reproducing amplifier for a two-terminal magnetic head that is Embodiment 2 of the present invention. 1 ... Recording amplifier, 2 ... 2-terminal thin film magnetic head (2-terminal magnetic head), 3 ... Recording level converter for upper stage, 4 ...
... first damping (first damping means), 5 ... second damping (second damping means), 5A ... second damping (second damping means), 6 ... first recording level converter, 7 ... Lower signal level converter, 8 ... Regeneration amplifier, 9 ... Amplifier, 10,11,12 ... Current source, 13,14,
15 …… Switch, 101,102,103,104 …… Transistor, 1
05,106 …… resistor, 107,108 …… transistor, 109,110,1
11,112,113,114 …… resistor, 115,115a, 116,116a …… diode (switch means), 117,118 …… transistor, 1
21,122 …… Capacitor, 123,124 …… Transistor, 12
5,126 …… Load resistance, 201,202,203,204,205 …… Record signal, 206,207 …… Playback output.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsutaka Onizawa 2880 Kozu, Odawara, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Kazuhisa Shiraishi 2880, Kozu, Odawara, Kanagawa Hitachi Ltd. Odawara In-factory (72) Inventor Maki Yoshinaga 2326 Imai, Ome-shi, Tokyo Inside Device Development Center, Hitachi, Ltd. (56) Reference JP-A 63-16401 (JP, A)

Claims (3)

[Claims] 1. A recording amplifying section for supplying a recording current to a two-terminal magnetic head, a signal level converting section for supplying a signal corresponding to information to be recorded to the recording amplifying section, and reproduction from the two-terminal magnetic head. A recording / reproducing amplifier for a two-terminal magnetic head, comprising a reproducing / amplifying unit for amplifying a signal, the resistor being interposed between a terminal of the two-terminal magnetic head and a reference voltage source connected to the recording / amplifying unit. A first damping means formed of an element, a switch means that operates at the time of recording, and a resistance element connected in series to the switch means, and a terminal of the two-terminal magnetic head in parallel with the first damping means. A second damping unit interposed between the recording amplifier and a reference voltage source connected to the recording amplifier, the recording amplifier having an emitter side connected to the two-terminal magnetic head; A first side and a second side transistor connected to the reference voltage source to form an upper stage portion, and a third side and a fourth transistor connected to the two-terminal magnetic head to form a lower stage portion on the collector side. , The first transistor in the upper stage and the fourth transistor in the lower stage, and the second transistor in the upper stage and the third transistor in the lower stage form a group, and the groups are alternately turned on / off. A recording / reproducing amplifier for a two-terminal magnetic head, wherein the recording current flowing in the two-terminal magnetic head is alternately inverted by repeating OFF. 2. A recording / reproducing amplifier for a two-terminal magnetic head according to claim 1, wherein said switch means constituting said second damping means is a diode whose anode side is connected to said reference voltage source. . 3. A recording / reproducing amplifier for a two-terminal magnetic head according to claim 1, wherein a capacitive element is added in series to said second damping means.