JPH0467303A - Write/read circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To realize a magnetic disk device in which a position error signal can be obtained even in the middle of a write operation and which has a high positioning precision by obtaining reproduced output from a read/write head in the middle of the write operation and writing a servo signal, for example, in a deep layer which is not used in data recording. CONSTITUTION:A write waveform generation circuit 1 outputs a write waveform similar to the output of the read/write head 2 in the middle of the write operation. The output 22-23 and the output 24-25 of the read/write head 2 are added to a subtraction circuit 5, and the output is set to be the input 27-26 of a read circuit 4. Thus, the change of a magnetic field, which the head reproduced from the medium can be amplified and reproduced in the read circuit 4 even while the read/write head 2 writes data. Furthermore, servo information in the deep layer part 11b is amplified and reproduced in the read circuit 4 while data is written in the surface part 11a of the magnetic disk medium 11 and it can be used as the servo signal of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk drive, and more particularly to a write/read circuit and a device using the same.

[Conventional technology]

Conventionally, in the write/read circuit of this type of magnetic disk device, only the output of the read/write head is directly connected to the read amplifier.

[Problem to be solved by the invention]

In the conventional write/read circuit described above, only the output of the read/write head was directly connected to the read amplifier.
During a write operation, the read circuit input is saturated due to a voltage drop due to the flyback voltage and write current, resulting in a drawback that a read operation cannot be performed.

[Means to solve the problem]

The present invention relates to a write/read circuit for a magnetic disk device, which includes a read/write head for writing or reading information on a magnetic disk medium, and a read/write head connected to the read/write head so that the read/write head performs a write operation. a write circuit; a write waveform generation circuit that generates a pseudo write waveform equivalent to the output of a read/write head when the write circuit performs a write operation on a magnetic disk medium;
It has a subtraction circuit that performs subtraction between the output of the read/write head and the output of the write waveform signal generation circuit, and a readout circuit that inputs and amplifies the output of the subtraction circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a write waveform signal generation circuit diagram, Fig. 3 is a diagram showing waveforms of each part of Fig. 1, and Fig. 4 is a waveform of each part of Fig. 3. FIG.

In FIG. 1, a write control signal 20 and a write data signal 21 are input to a write waveform signal generation circuit 1 and a first write circuit 3, and the output of the first write circuit 3 is connected to a read/write head 2. Furthermore, it is connected to one input of the subtraction circuit 5 as a head output signal. Further, the output of the write waveform generation circuit 1 is similarly connected to the other input of the subtraction circuit 5, and the output 2627 of the subtraction circuit 5 is connected to the other input of the subtraction circuit 5.
is connected to the readout circuit 4.

Here, the write waveform generation circuit 1 is a circuit that outputs a write waveform similar to the output of the read/write head 2 during a write operation, and for example, as shown in FIG. By using the second write circuit 12 that has the same characteristics as the RAD 11 and the write circuit 3, it is possible to easily create a write waveform similar to the output of the read/write head 2, and it is also possible to make a comparison using an equivalent circuit. It can be easily realized.

Further, the magnetic disk medium 13 is composed of a surface layer 13a and a deep layer 13b. The surface layer 13a is used for recording and reproducing data, and servo information is written in the deep layer 13b.

Next, FIG. 3 shows the output waveforms of each part in FIG. 1.

All outputs are expressed as differential. Here, the outputs 22-23 of the write waveform signal generation circuit 1 and the outputs 24-25 of the read/write head 2 are added in opposite phases to each other via the resistor of the subtraction circuit 5, and the outputs are applied to the input 2 of the readout circuit 4.
It becomes 7-26. Compared to the output of the original read/write head 2, this signal 27-26 is much less influenced by the voltage drop at the head due to flyback voltage and write current, and is amplified within the dynamic range of the input of the readout circuit 4. has a possible amplitude.

As a result, even when the read/write head 2 is writing data, the read circuit 4 can amplify and reproduce changes in the magnetic field that the head is reproducing from the medium, and write data on the surface layer 11a of the magnetic disk medium 11. While
The servo information in the deep portion 11b is amplified and reproduced by the readout circuit 4, and is used as a servo signal for the device.

In this case, the outputs 24-25 have surface layer signals 24-25 (a) and deep layer signals 24-25 (b) as shown in FIG.
The surface layer/deep layer composite playback signal 24-25
(C), and the reproduced waveforms 24-25 during writing (
d) and amplifies it to output the amplifier output 28.
-29 (e) and pass it through a filter to reproduce the deep signal.

〔Effect of the invention〕

As explained above, according to the present invention, reproduction output is obtained from the read/write head during a write operation, so by writing, for example, a servo track signal in a deep layer that is not used for data recording, the write operation can be performed. Among these, a position error signal can be obtained, and a highly reliable magnetic disk device with high positioning accuracy can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a write waveform signal generation circuit diagram, FIG. FIG. 3 is a diagram showing a surface signal and a deep signal in a waveform. DESCRIPTION OF SYMBOLS 1... Write waveform generation circuit, 2... Read/write head, 3... First write circuit, 4... Read circuit, 5... Subtraction circuit, 11... Dummy head, 12...
... second write circuit, 13 ... magnetic disk medium,
13a...surface layer part, 13b...deep layer part, 20...
Write control signal, 21...Write data signal, 22-
23... Output of write waveform generation circuit 1, 24-25.
...Output of read/write head 2, 26-27...Input of readout circuit 4, 28-29...Output of readout circuit 4, 24-25 (a)...Surface signal, 24-25(
b)...Deep signal, 24-25(c)...Surface layer/deep layer combined reproduced signal, 24-25 (d)...Reproduced waveform during writing, 28-29 (e)...Amplifier output.

Claims (1)

[Scope of Claims] A read/write head for writing or reading information on a magnetic disk medium, a write circuit connected to the read/write head and for performing a write operation with the read/write head, and the write circuit. a write waveform generation circuit that generates a pseudo write waveform equivalent to the output of the read/write head when the read/write head performs a write operation on the magnetic disk medium; and the read/write head output and the write waveform signal generation circuit. A magnetic disk device comprising: a subtraction circuit that performs subtraction with an output; and a readout circuit that inputs and amplifies the output of the subtraction circuit.