JP2786338B2 - Magnetic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording apparatus,
In particular, it relates to an improvement in a recording amplifier in a magnetic recording device.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration of a conventional magnetic recording apparatus. In the figure, 1 is a DC voltage power supply, 2 is an AC voltage signal source connected in series to the DC voltage power supply 1, 3 is a recording current amplifier having an AC voltage signal source 2 as an input, 4a, 4b,
4c and 4d are np connected to the output of the recording current amplifier 3.
switches composed of n transistors, 11a and 11
b, 11c and 11d are switches 4a, 4b and 4 respectively.
control signal sources for controlling c and 4d, 14a and 14
b, 14c and 14d are switches 4a, 4b and 4 respectively.
c, 4d, terminals for outputting signals to the outside, 7a, 7b, 7c, 7d are terminals 14a, 1d, respectively.
4b, 14c, 14d connected capacitors, 9a,
9b, 9c and 9d are capacitors 7a, 7b and 7 respectively.
current limiting resistors connected to c, 7d, 8a, 8b, 8
c and 8d are current limiting resistors 9a, 9b, 9c and 9 respectively.
d, capacitors 15a, 15b, 15c,
15d is a terminal for inputting a signal inside, 5a, 5
b, 5c and 5d are terminals 15a, 15b and 15 respectively.
switches 6a, 6b, 6c, and 6d are DC voltage power supplies connected to switches 5a, 5b, 5c, and 5d, respectively.
12a, 12b, 12c and 12d are switches 5 respectively.
a, 5b, 5c, 5d. Reference numerals 10a, 10b, 10c, and 10d are heads connected to the current limiting resistors 9a, 9b, 9c, and 9d, respectively, for recording signals on a magnetic medium.

Next, the operation will be described. The voltage of the AC voltage signal source 2 superimposed on the DC voltage power supply 1 is current-amplified by the recording current amplifier 3. The output of the recording current amplifier 3 is controlled by switches 4a, 4b, 4c, and 4d by heads 10a, 1a.
The periods for supplying the signal currents to 0b, 10c, and 10d are switched. Switches 4a, 4b, 4c, 4
The switching control of d is performed by control signal sources 11a and 11
The control is performed based on the control signals from b, 11c, and 11d, and the control signal waveform is shown in FIG. Switch 4a,
The switching timing of 4b, 4c, 4d is turned on when the control signals from the control signal sources 11a, 11b, 11c, 11d shown in FIG. 4 are high. Therefore, t ₁ , t ₂ ,
At times t ₃ and t _4, the heads 10a, 10b, 1
Signal currents flow sequentially in 0c and 10d and are recorded.

[0004] For example, in the period t ₁ the switch 4a is turned on, 4b, 4c, 4d is off, the terminal 14b, 14c, 14d has become impedance in the open state is high. In such a state, a signal easily jumps into the heads 10b, 10c, and 10d, and a crosstalk signal may be written on a recording medium although a recording current should not originally flow. To prevent this, switches 5a, 5b, 5
c, 5d are provided.

The switches 5a, 5b, 5c and 5d are controlled by control signals from control signal sources 12a, 12b, 12c and 12d, respectively. FIG. 4 shows the waveforms of the control signals. That is, as shown in FIG. 4, only the timing t ₁ the control signal source 12a is in wax, other control signal source 12
Since b, 12c and 12d are on, the switch 5a is off, the switches 5b, 5c and 5d are on and the terminal 1
5b, 15c and 15d are internal DC voltage power supplies 6b and 6
Because they are connected to c and 6d and have low impedance,
Crosstalk is less likely to occur.

FIG. 5 shows a specific configuration example of the recording current amplifier 3 shown in FIG. In the figure, 21 is a signal input terminal, and 22 and 23 are NPN constituting an emitter follower.
Bipolar transistors and PNP bipolar transistors, 24 and 25 are transistors constituting an output push-pull, and 26 is an output terminal. Transistor 27,
Reference numerals 28, 29, 30 and resistors 31, 32, 33, 34 denote constant current circuits, transistor 37 and resistors 35, 36 denote voltage sources for determining a constant current value, 38 denotes a power supply terminal, and 39 denotes a ground terminal.

A signal input from a terminal 21 passes through a transistor 22 constituting an emitter follower, is applied to an output transistor 25, and is current amplified. On the other hand, the signal passing through the transistor 23 forming the emitter follower enters the transistor 24 and is amplified. Since the emitters of the transistors 24 and 25 are commonly connected, the transistors 24 and 25 are connected to each other when a current flows from the output terminal 26.
Operates, and the transistor 25 operates when sinking current. Also, in order to allow a sufficient recording current to flow through the head without distortion, an idle current of about 6 mA is normally passed.

[0008]

The conventional magnetic recording apparatus is configured as described above, and requires a terminal for lowering the impedance for eliminating crosstalk, thereby increasing the circuit scale. .

When the standby state in which the switches 4a, 4b, 4c, 4d are all turned off continues for a long time, the capacitors 7a,
7b, 7c, and 7d leak, thereby lowering the voltage held in the capacitor. At the moment when the standby state is released, the charging current of the capacitor flows instantaneously. However, there is a problem that is incorrectly recorded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to prevent crosstalk without increasing the overall current consumption and to reduce the number of external components and terminals. The purpose is to get.

[0011]

According to the present invention, there is provided a magnetic recording apparatus comprising: a DC voltage source for supplying a DC bias voltage;
And an AC voltage signal superimposed on the DC bias voltage.
, A plurality of recording heads,
The amplified AC voltage signal is amplified, and the amplified AC voltage signal is amplified.
Is supplied to the recording head via a capacitor.
A plurality of recording current amplifiers
The applied DC bias voltage is sequentially applied to the plurality of recording current amplifiers.
Next, and input the DC bias voltage to the AC voltage signal.
Recording voltage to which no DC bias voltage with
Input to the current amplifiers
Switching means for switching the input of each
is there. Further, the magnetic recording apparatus according to the present invention is characterized in that
The current amplifier is connected to a DC bypass on which the AC voltage signal is superimposed.
When the bias voltage is input, the recording head
Of sufficient value to supply the widened AC voltage signal without distortion.
The idle current flows and the DC bias voltage is turned on.
When the power is supplied, the
It is configured to flow an idle current .

[0012]

According to the magnetic recording apparatus of the present invention, the recording current amplifiers are provided by the number of heads, and the input signal of the recording current amplifier is switched by a plurality of switches on the input side of the recording current amplifier, and the recording current is not supplied to the recording head. Also outputs a DC voltage that is the same as the DC bias voltage when the recording current flows through the recording head, so that the DC voltage is always applied to the capacitor even when the recording head is off, and the output DC voltage does not change whether it is on or off. Even in the standby state, the capacitor always holds the same charge, and no instantaneous current flows through the recording medium when the standby state is released. Meanwhile, the head
The impedance at the end is low,
The write of the peak signal is prevented.

In the present invention, the idle current at the output stage of the recording current amplifier when the recording current is not supplied to the recording head is made smaller than the idle current when the recording current is supplied to the recording head. , increase in power consumption is suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic recording apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a magnetic recording apparatus according to an embodiment of the present invention. In the drawing, reference numeral 1 denotes a DC voltage power supply, 2 denotes an AC voltage signal source connected in series to the DC voltage power supply 1, 3a, 3b, Reference numerals 3c and 3d denote recording current amplifiers provided in the same number as the number of heads, 13a, 13b, 13c,
13d denotes recording current amplifiers 3a, 3b, 3c, 3 respectively.
A switch for selecting whether to input an AC signal to the input of d with the same DC voltage. 11a, 11b, 11
c and 11d are switches 13a, 13b and 13 respectively.
c, 13d and recording current amplifiers 3a, 3b, 3c, 3
control signal sources for controlling d, 14a, 14b, 14
c and 14d are recording current amplifiers 3a, 3b and 3 respectively.
c, 3d, terminals for outputting signals to the outside, 7a, 7b, 7c, 7d are terminals 14a, 1d, respectively.
Capacitors connected to 4b, 14c, 14d, 10
a, 10b, 10c and 10d are capacitors 7 respectively.
a, 7b, 7c and 7d are heads for recording signals on a magnetic medium.

Next, the operation will be described. Switch 13
The signal of the AC signal source 2 superimposed on the bias voltage of the DC voltage power supply 1 is applied to each terminal a of the terminals a, 13b, 13c, and 13d, and the bias voltage of the DC power supply 1 is applied to the terminal b. I have. Switches 13a, 13b, 13c,
13d are control signal sources 11a, 11b, 11c,
11d, and the waveform of the control signal is as shown in FIG. Switches 13a, 13b, 1
3c and 13d are control signal sources 11a, 11b,
When the control signals from 11c and 11d are high, they are on the terminal a side, and when they are low, they are on the terminal b side.

Therefore, the recording current amplifiers 3a, 3b, 3
The same DC bias voltage is always output from c and 3d, and the capacitors 7a, 7b, 7c and 7d are always kept at the same voltage. Assume that the switches 13a, 13b,
13c and 13d are all on the terminal b side, and even if there is no signal at any output, the capacitor 7
Since a, 7b, 7c, and 7d have the same DC voltage, no current flows even at the moment when the standby state is released, thereby preventing erroneous writing of the instant signal on the recording medium.

However, in the configuration of this embodiment, the number of recording current amplifiers is increased as compared with the above-described conventional configuration.
If left untouched, the overall current consumption will increase significantly. Therefore, in the present embodiment, the recording current amplifiers 3a, 3b, 3c,
3d is configured as shown in FIG. That is, FIG. 2 shows a specific circuit configuration of a recording current amplifier of a magnetic recording apparatus according to an embodiment of the present invention. In the drawing, the same reference numerals as those of the conventional recording amplifier amplifier shown in FIG. The same or corresponding parts are shown, and 35a and 35b are transistors 2
The transistors 40 and the base resistor 41 are switches for switching the constant current, and the terminal 42 is a control terminal for switching the constant current.

In this circuit configuration, a transistor 40, a base resistor 41 and a control terminal 42 are added to the conventional device shown in FIG. 5, and the collector of the transistor 40 is connected between the resistors 35a and 35b. . Since the control terminal 42 is at a high resistance 3 5b are short-circuited by the transistor 40, the voltage of the voltage source that determines the constant current is lowered, the transistors 27, 28 and resistors 31 and 32,
The current value of the constant current source constituted by 33 and 34 decreases. Conversely, when the control terminal 42 is low, the voltage of the voltage source that determines the constant current decreases and the constant current value increases.

The control terminal 42 is connected to the control signal source 11a,
11b, 11c, and 11d, respectively, and by the above operation, the control signal sources 11a, 11b, 11c, and 11d.
Is high, the constant current is increased and the control signal sources 11a, 1
When 1b, 11c and 11d are low, the constant current is reduced.
Since the idle current flowing through the transistors 24 and 25 is proportional to the constant current, for example, when the terminal 42 is low, if the resistors 35a and 35b are selected so that the constant current becomes 1/10, the idle current becomes, for example, 6 mA to 0.1 mA. It is reduced to 6 mA.
When the idle current is 0.6 mA, the impedance of the output terminal 26 is about 22 ohms, which is the ON resistance 2 of the switches 5a, 5b, 5c, 5d of FIG.
This is not a problematic size compared to 0 ohms, and this can reduce crosstalk.

The total current consumption is 6 mA for the recording current amplifier turned on and 0.6 mA for the other three recording current amplifiers turned off.
Switches 4a, 4b, 4c, 4d and 5a, 5b, 5
It can be made smaller than the current for controlling c and 5d.

According to this embodiment, a terminal for lowering the impedance for eliminating crosstalk, which is conventionally required, is not required, so that the number of external components and terminals can be greatly reduced. The cost and size of the device can be reduced.

The recording current amplifiers 3a, 3b, 3c,
3d to the heads 10a, 10b, 10c, 10d, respectively.
Switches 13a, 13b, 13
recording current amplifiers 3a, 3b, 3c, 3
As the output of d, either the bias voltage of the DC power supply 1 or the voltage of the AC signal source superimposed on the bias voltage of the DC power supply is output. The same DC voltage as the DC bias voltage when the recording current is supplied to the recording head is output, so that the DC voltages of the capacitors 7a, 7b, 7c, and 7d remain unchanged regardless of whether they are on or off. Also, the same charge is always held in the capacitors 7a, 7b, 7c, 7d, and an instantaneous current flows when the standby state is released, so that the instantaneous signal is not erroneously written on the recording medium.

Each recording current amplifier is configured as shown in FIG. 2, and the idle current at the output stage of the recording current amplifier when the recording current is not supplied to the recording head is the idle current when the recording current is supplied to the recording head. Power consumption can be reduced to the same level as or less than the conventional one, and the impedance of the output terminal 26 can be reduced to the same level as the on-resistance of the conventional switches 5a, 5b, 5c, and 5d. Therefore, crosstalk can be reduced as in the related art.

[0024]

As described above, in the present invention, a recording current amplifier is provided for each head, and the same DC voltage as the DC bias voltage when the recording current is supplied to the recording head even when the recording current is not supplied to the recording head. Is output.
The DC voltage of the capacitor does not change whether it is on or off, and the same charge is always held in the capacitor even in the standby state, an instantaneous current flows when the standby state is released, and the instantaneous signal is erroneously written on the recording medium There is an effect that it can be prevented from being performed. Also, the impedance at the head end
Lowering crosstalk
There is fruit.

Further, since the idle current at the output stage of the recording current amplifier when the recording current is not supplied to the recording head is set to be smaller than the idle current when the recording current is supplied to the recording head, the power consumption is the same as the conventional one. There is an effect that it can be reduced to or less .

Further, according to the present invention, since a terminal for lowering impedance for removing crosstalk is not required, the number of external parts and terminals can be greatly reduced, and the cost and the size of the magnetic recording apparatus can be reduced. There is also an effect that it can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a magnetic recording apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a recording current amplifier of the magnetic recording device according to one embodiment of the present invention.

FIG. 3 is a diagram showing a conventional magnetic recording device.

FIG. 4 is a diagram showing a control signal waveform of each switch in the magnetic recording apparatus of the present invention and the conventional example.

FIG. 5 is a diagram showing a configuration of a recording current amplifier of a conventional magnetic recording device.

[Explanation of symbols]

Reference Signs List 1 DC voltage power supply 2 AC signal sources 3a, 3b, 3c, 3d Recording current amplifiers 13a, 13b, 13c, 13d Input changeover switches 11a, 11b, 11c, 11d Switch control signal lines 7a, 7b, 7c, 7d Capacitors 10a, 10b , 10c, 10d Heads 14a, 14b, 14c, 14d Terminal 21 Signal input terminal 38 Power supply terminal 39 Ground terminal 31, 32, 33, 34, 35a, 35b, 36, 41
Resistance 22, 24, 27, 30, 37 NPN bipolar transistor 23, 25, 28, 29 PNP bipolar transistor 26 Signal output terminal 42 Constant current switching control terminal

Claims (2)

(57) [Claims] 1. A direct current for supplying a direct current bias voltage.
An AC voltage signal is superimposed on the voltage source and the DC bias voltage.
An AC voltage signal source, a plurality of recording heads, and the AC voltage signal.
No. is supplied to the above recording head via a capacitor.
A plurality of recording current amplifiers and a DC bias voltage on which the AC voltage signal is superimposed.
Input to a plurality of recording current amplifiers sequentially, and
The bias voltage to a DC bias on which the AC voltage signal is superimposed.
Make sure that no voltage is input to the recording current amplifier.
Switching between inputs to multiple recording current amplifiers
A magnetic recording device comprising: a switching unit. 2. The magnetic recording apparatus according to claim 1, wherein
Te, the recording current amplifier, the alternating voltage signal is superimposed
When a DC bias voltage is input, the recording head
To supply the amplified AC voltage signal without distortion
Pass a sufficient value of idle current, and
When the idle voltage is input, it is smaller than the value of the idle current.
A magnetic recording apparatus characterized in that an idle current having a small value is passed.