JPH05101313A - Recording and reproducing circuit - Google Patents

Abstract

PURPOSE:To improve storage capacity and the followup ability of a frequency on a recording and reproducing circuit in a magnetic disk device. CONSTITUTION:This circuit is constituted so that a switching means 21 switching a regenerative output is provided and simultaneously a waveform generating means 22 generating an AC waveform with a prescribed amplitude is provided. and the AC waveform is switched to be outputted to an AGC circuit 20 under writing and the regenerative output is switched to be outputted to the AGC circuit 20 after the writing is ended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing circuit in a magnetic disk device. AGC of magnetic disk unit
The circuit adjusts the reproduction output from the head drive circuit so as to have a predetermined amplitude.
In the case of d, there is a delay in the output time and a transient occurs.

It is necessary to prevent the occurrence of such transients and improve the storage capacity.

[0003]

2. Description of the Related Art As a conventional recording / reproducing circuit, for example, there is one shown in FIG. In FIG. 6, the data is temporarily stored in the write buffer memory 1, and the modulation circuit 2
After being modulated by, the data is written on the recording medium (magnetic disk) 5 by the head drive circuit 3 via the magnetic head 4.

That is, when the write gate signal from the controller 6 is at a high level (write level), the head drive circuit 3 performs a write operation. When the write gate signal becomes low level (read level), the head drive circuit 3 performs a read operation of reading data from the recording medium 5 via the magnetic head 4 and outputs it to the AGC circuit 7.

The AGC circuit 7 adjusts the reproduction output from the head drive circuit 3 to a constant amplitude. The reproduction output adjusted to have a constant amplitude is demodulated by the demodulation circuit 8 and then stored in the read buffer memory 9. Reference numeral 10 is a read / write control circuit. Next, the output of the AGC circuit 7 is shown in FIG. In FIG. 7, a indicates a write gate signal output from the controller 6 to the head drive circuit 3. When the write gate signal is at high level, writing is performed, and when it is at low level, reading is performed. b is the AGC circuit 7
Shows the output of. (1) shows the delay time, (2) shows the gap length, and (3) shows the transient in the case of Write to Read.

[0006]

However, in such a conventional recording / reproducing circuit, when the reproduction output is input at the time of reading, there is a delay in the output of the AGC circuit and a transient occurs, so that the gap length is reduced. The delay time was covered by securing a wide range. As a result, there is a problem that the gap length included in the format becomes large, the storage capacity cannot be improved, and the frequency followability cannot be improved.

The present invention has been made in view of such conventional problems, and provides a recording / reproducing circuit capable of improving the storage capacity and the frequency tracking capability by shortening the gap length. The purpose is to

[0008]

FIG. 1 illustrates the principle of the present invention. According to the present invention, as shown in FIG. 1, when the write gate signal from the higher-level device is at the write level, the write data from the higher-level device is passed through the magnetic head 14 to the magnetic disk 1.
9 and the reproduction output of the magnetic head 14 is output from the AGC circuit 20 when the write gate signal from the host device is at the read level.
In the recording / reproducing circuit that amplifies and outputs to a constant amplitude by means of the waveform generating means 2 for generating an AC waveform having a predetermined amplitude.
2 and switching means 21 for outputting either the output of the waveform generating means 22 or the reproduction output from the magnetic head 14 to the AGC circuit 20. The switching means 21 generates a waveform when the write gate signal is at the write level. The output of the means 22 is AGC
It is configured to output to the circuit 20 and to output the reproduction output of the magnetic head 14 to the AGC circuit 20 when the write gate signal is at the read level.

[0009]

During writing, the switching means switches to the waveform generating means, and the AC waveform having a predetermined amplitude generated by the waveform generating means is output to the AGC circuit. This allows AGC
The circuit is ready to output with a predetermined amplitude during writing. When the write is changed to the read, the switching means outputs the reproduction output to the AGC circuit.

Since the output of the AGC circuit is adjusted in advance so as to have a constant amplitude, the reproduction output can be output at a predetermined amplitude without delay by inputting the reproduction output, and the unstable component at the time of rising is removed. Outputs a waveform with constant amplitude. Therefore, the transient of the AGC circuit can be removed and the gap length can be shortened. as a result,
Since the gap length previously included in the format can be shortened, the storage capacity can be improved.

Further, since the AGC circuit outputs a waveform having a constant amplitude without an unstable component at the time of rising, it is possible to improve the frequency tracking ability.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 2 to 4 are views showing an embodiment of the present invention.
In FIG. 2, 11 is a write buffer memory, and the write buffer memory 11 temporarily stores data. 12
Is a modulation circuit, and the modulation circuit 12 modulates the data from the write buffer memory 11.

Reference numeral 13 denotes a head drive circuit. The head drive circuit 13 selects the magnetic head 14 and performs an amplifying action. As shown in FIG. 3, the head drive circuit 13 includes a plurality of buffer amplifiers 15 and 16 for performing amplification, for example.
And a plurality of selection circuits 17 for selecting the magnetic head 14. A write gate signal is given to the head drive circuit 13 from the controller 18, and when the write gate signal is at a high level, a write operation is performed, and when the write gate signal is at a low level, a read operation is performed.

The write data is recorded by the head drive circuit 13 via the magnetic head 14 to a recording medium (magnetic disk).
Written in 19. The data written in the recording medium 19 is read via the magnetic head 14 and amplified by the head drive circuit 13. 20 is an AGC circuit,
The C circuit 20 adjusts the reproduction output of the head drive circuit 13 to a constant amplitude.

Reference numeral 21 is a reproduction output switching circuit as a switching means. The reproduction output switching circuit 21 is a head drive circuit 13.
And the AGC circuit 20. Reference numeral 22 denotes an AC waveform generating circuit as a waveform generating means. The AC waveform generating circuit 22 generates an AC waveform having a predetermined amplitude and outputs it to the reproduction output switching circuit 21. The AC waveform generating circuit 22 generates an AC waveform having the same frequency and the same amplitude as the data written in the gap portion.

A write gate signal is input from the controller 18 to the reproduction output switching circuit 21, and the reproduction output switching circuit 21 outputs to the AC waveform generating circuit 22 when the write gate signal is at a high level, that is, during writing. When the write gate signal is switched to the AGC circuit 20 and the write gate signal is at a low level, that is, during reading, the head drive circuit 13 is switched and the reproduction output is reproduced.
Send to 0.

Reference numeral 23 is a demodulation circuit, and the demodulation circuit 23 is
The output of the AGC circuit 20 is demodulated. The demodulated data is stored in the read buffer memory 24 and then output to the controller 18. The controller 18 controls each part, and also sends a write gate signal to the head drive circuit 13 and the reproduction switching circuit 21. Incidentally, 25 is a write buffer memory 11, a read buffer memory 24,
A read / write control circuit for controlling the modulation circuit 12 and the demodulation circuit 23.

Next, the operation will be described. The data temporarily stored in the write buffer memory 11 is stored in the modulation circuit 12
After being modulated by, the head drive circuit 13 writes the data on the recording medium 19 via the magnetic head 14. During this writing, that is, while the write gate signal output from the controller 18 to the head drive circuit 13 and the reproduction output switching circuit 21 is at the high level, the reproduction output switching circuit 2
1 is switched to the AC waveform generating circuit 22.

Therefore, the predetermined AC waveform generated by the AC waveform generating circuit 22 is sent to the AGC circuit 20 via the reproduction output switching circuit 21. The AGC circuit 20 is adjusted in advance so that the output has a constant amplitude during writing. When the write gate signal becomes low level, the reproduction output switching circuit 21 switches from the AC waveform generating circuit 22 to the head driving circuit 13. As a result, the reproduction output from the head drive circuit 13 enters the AGC circuit 20 via the reproduction output switching circuit 21. In this case, the AGC circuit 20
The output is adjusted in advance so as to have a constant amplitude, and the reproduction output from the head drive circuit 13 is output with no delay from the time of switching to the lead and without transient (see FIG. 4).

Therefore, the transient of the AGC circuit 20 can be removed and the gap length can be shortened. As a result, the storage capacity can be improved. Further, since the AGC circuit 20 is adjusted in advance so that the AC waveform has a constant amplitude, it is possible to improve the frequency followability. Next, FIG. 5 is a diagram showing another embodiment of the present invention.

In FIG. 5, reference numeral 26 is a constant voltage generating circuit as a constant voltage generating means.
Generates a predetermined constant voltage and outputs it to the reproduction output switching circuit 21. While the write gate signal output to the reproduction output switching circuit 21 is at the high level, the reproduction output switching circuit 21 switches to the constant voltage generating circuit 26.

Therefore, a predetermined constant voltage is sent to the AGC circuit 20 via the reproduction output switching circuit 21. AGC
As the circuit 20, there is one that is made into one chip and that converts the reproduction output into a voltage. In such an AGC circuit 20, when a constant voltage is input, the output is adjusted in advance so as to have a predetermined amplitude. In this state, when the reproduction output is input to the AGC circuit 20, there is no delay from the time of switching to the read, and a waveform having a constant amplitude with no transient is output (see FIG. 4).

Therefore, also in this embodiment, the same effect as that of the above embodiment can be obtained.

[0024]

As described above, according to the present invention, the AG is switched in advance by switching by the switching means during writing.
A predetermined AC waveform or a constant voltage is output to the C circuit, and the head drive circuit is switched during reading to reproduce the output.
Since it is output to the GC circuit, there is no delay in output, transients can be removed, and the gap length can be shortened, so that the storage capacity can be improved and the frequency followability can be improved. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a configuration diagram of a head drive circuit.

FIG. 4 is an output waveform diagram of the AGC circuit.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is a diagram showing an output of a head drive circuit.

[Explanation of symbols]

 11: Write buffer memory 12: Modulation circuit 13: Head drive circuit 14: Magnetic head 15 and 16: Buffer amplifier 17: Selection circuit 18: Controller 19: Recording medium (magnetic disk) 20: AGC circuit 21, 22: Operational amplifier 23: Demodulation circuit 24: Read buffer memory 25: Read / write control circuit 26: Constant voltage generation circuit (constant voltage generation means)

Claims (2)

[Claims] 1. When the write gate signal from the host device is at the write level, the write data from the host device is recorded on the magnetic disk (19) via the magnetic head (14), and the write gate signal from the host device is read. A waveform generating means (22) for generating an AC waveform of a predetermined amplitude in a recording / reproducing circuit that amplifies the reproduction output of the magnetic head (14) to a constant amplitude by the AGC circuit (20) and outputs it when the level is reached.
And the output of the waveform generating means (22) and the magnetic head (1
One of the reproduction outputs from 4) is supplied to the AGC circuit (2
0) is provided with a switching means (21) which outputs the output of the waveform generating means (22) to the AGC circuit (20) when the write gate signal is at the write level.
When the write gate signal is at the read level, the magnetic head (1
A recording / reproducing circuit characterized in that the reproducing output of 4) is outputted to the AGC circuit (20). 2. When the write gate signal from the host device is at the write level, the write data from the host device is recorded on the magnetic disk (19) via the magnetic head (14), and the write gate signal from the host device is read. A constant voltage generating means (26) for generating a constant voltage in a recording / reproducing circuit that amplifies the reproduction output of the magnetic head (14) to a constant amplitude by an AGC circuit (20) and outputs it when the level is at a constant level. Output of means (26) and magnetic head (14)
A switching means (21) for outputting one of the reproduction output from the AGC circuit (20) is provided, and the switching means (21) is provided.
Outputs the constant voltage of the constant voltage generating means (26) to the AGC circuit (20) when the write gate signal is at the write level,
When the write gate signal is at the read level, the magnetic head (1
A recording / reproducing circuit characterized in that the reproducing output of 4) is outputted to the AGC circuit (20).