JP2565198B2 - Magnetic disk device - Google Patents

Description

The present invention relates to a magnetic disk device such as a hard disk device or a floppy disk device connected to a computer.

[Outline of Invention]

The present invention relates to a magnetic disk device, in which a preceding erasing head is provided to improve recording characteristics, and the timing of signals at that time is controlled to solve a problem such as erroneous erasing. .

[Conventional technology]

In magnetic disk devices such as hard disk devices and floppy disk devices connected to a computer,
Conventionally, a so-called erasing head is not provided, and rewriting of data has been performed by writing new data by so-called overwriting. In a conventional floppy disk device, there is a case where an erase head called a tunnel erase head is provided after the write / read head, but it is necessary to restrict the recording width of a written track. The purpose is different from the present application.

However, in recent years, as the recording density of data on the recording medium has been increased, it is necessary to increase the coercive force (Hc) of the magnetic material that constitutes the disk. It has become difficult to secure the S / N. Therefore, it is considered to provide an erasing head (preceding erasing head) at a position preceding the write / read head.

However, in this case, a physical space is formed between the write / read head and the erase head. For this reason, if writing with the write / read head and erasing with the erasing head are performed at the same timing, an extra erasing portion corresponding to the leading portion of the erasing head is generated at the end of writing, and this writing is performed on the disk. If an attempt is made to reach the end of the write area defined above, the start of the next write area will be erroneously erased due to the preceding erasure.

Here, in an ordinary magnetic disk device, recording tracks on the disk are formed in an annular shape, and the start and end ends thereof are adjacent to each other. If, for example, the above-mentioned writing area is defined so as to extend substantially around one track, a synchronization signal or control signal necessary for writing and reading may be written in advance at the start end portion thereof. However, in such a case, if the erroneous erasing as described above is performed, there is a possibility that the subsequent writing and reading may be seriously hindered.

[Problems to be solved by the invention]

As described above, the conventional technique has a problem in that writing and reading may be hindered by erroneous erasing when the preceding erasing head is provided.

[Means for solving problems]

The present invention relates to a drive means (motor (2)) for rotationally driving a rotary disk type recording medium (disk (1)) having a plurality of writing areas, and an index signal (Id) according to the rotation of the recording medium. An index signal generating means (PG (11)) for generating, a writing / reading head (3) for writing / reading on the recording medium, and an erasing head provided at a position preceding the writing / reading head by a predetermined distance. (4) and erase head control means (control circuit (5)) for controlling the erase head. Based on the index signal (Id), the write / read head is read from the next write area. Also, the magnetic disk device is characterized in that the erasing by the erasing head is completed (switch (8)) when it is detected that the predetermined interval has come.

[Action]

According to this, the recording characteristics are improved by providing the preceding erasing head, and the risk of erroneous erasing is eliminated by controlling the timing of the end of this erasing according to the interval with the write / read head. be able to.

〔Example〕

In FIG. 1, (1) is a disc as a recording medium, and the disc (1) is rotated by a motor (2) at a constant angular velocity and is written on an arbitrary track on the disc (1). The read head (3) and the erasing head (4) are in contact with a position preceding the head (3). The head (3) is connected to the data output terminal (6) through the write / read control circuit (5). Further, the erase current from the erase current source (7) is supplied to the head (4) through the switch (8).

Further, the write gate signal (WG) supplied to the write control input terminal (9) is supplied to the write / read control circuit (5) and the AND circuit (10).

Further, a PG (11) for detecting the rotation phase of the disk (1) is provided, and an index signal (Id) extracted from this PG (11) is supplied to a delay circuit (12) having a delay time T _D described later. . In addition, this delayed index signal (I
d ') is supplied to the set terminal S of the RS flip-flop (13) and the original index signal (Id) is supplied to the reset terminal R of the flip-flop (13), and the Q output of this flip-flop (13) Is supplied to the AND circuit (10). The switch (8) is on-controlled by the output signal of the AND circuit (10).

Further, the delayed index signal (Id ') from the delay circuit (12) is output to the index output terminal (14).

In this device, for example, as shown in FIG. 2A, a track (1) from a PG (11) is the same as a track of a disk (1) in which a gap portion and a data portion in which a prescribed sync signal is recorded are formatted. As shown in FIG. B, the index signal (Id) is generated at a position T _D ahead of the start / end portion of the track.

Where the value of T _D is However, Gl is the distance between the heads (3) and (4), and v is the relative speed at the innermost circumference.

As a result, the delay circuit (12) outputs the signal (Id ') to the position corresponding to the start and end portions as shown in FIG. This signal (Id ') is the flip-flop (13).
Is supplied to the set terminal S and the original signal (Id) is supplied to the reset terminal R, so that the Q terminal of the flip-flop (13) has T _D immediately before the start and end portions as shown in FIG. An erase gate signal (EG) having a low potential is formed during the period.

On the other hand, the above-mentioned signal (Id ′) is transmitted to the index output terminal (1
4) is taken out. This allows an external controller (not shown) to output a signal (I
The signal taken out to the data input terminal (6) is detected from the time when d ') is supplied, and the write data is output from the time when the gap portion ends at the time of writing after the synchronization is pulled in. Supply to 6). At the same time, a write gate signal (WG) as shown in FIG. 8E is supplied to the control input terminal (9).

Then, the write gate signal (WG) is supplied to the write / read control circuit (5) to write data in this period, and the write gate signal (WG) and the flip-flop (13) The erase gate signal (EG) of the AND circuit (1
0) to form an erase control signal (E) as shown in FIG. F, and the switch (8) is on-controlled during the high potential period of this signal (E).

Therefore, in this device, during the writing of data, the control circuit (5) is set to the writing state during the period of the data, the erase current is supplied to the preceding erase head (4) through the switch (8), and the erase current is Is the index signal (I
It is cut off before T _D when d ′) is generated, and there is no risk of accidentally erasing the beginning and end of the recording track.

Thus, according to the above-described device, the recording characteristics can be improved by providing the preceding erasing head, and the timing of the end of this erasing is controlled according to the interval between the erasing head and the writing / reading head to prevent erroneous erasing. It is possible to eliminate the possibility of occurrence.

In the above-mentioned device, the external controller or the like considers the signal (Id ') as an index signal to operate, but in this case, this signal (Id')
If the disk (1) is formatted by using, this device can be handled from the outside in exactly the same way as the conventional one, and there is no need to modify the existing system, etc. Can be replaced.

Further, in this case, even if the value of Gl is changed, it can be dealt with only by changing the internal value of T _D , and the external controller or the like is not affected.

Furthermore, in the above-mentioned device, the delay circuit (12) of T _D can be configured by using a monostable multivibrator, a counter, a delay line, or the like, or a plurality of PGs (11) are provided to mechanically provide a signal (Id ′). ) May be formed.

The formation of the erase gate signal (EG) does not depend on the flip-flop (13), but if the time for one rotation of the disk (1) is known, the signal (Id ') indicates a monostable multivibrator or the like. It can also be formed by triggering.

Furthermore, the above-mentioned device is applicable even when the recording track of one round of the disc (1) is divided into a plurality of sectors as long as the index signal is formed at each boundary of these sectors. It is possible.

〔The invention's effect〕

According to the present invention, the recording characteristic is improved by providing the preceding erasing head, and the timing of the end of the erasing is controlled according to the interval between the erasing head and the writing / reading head, so that the erroneous erasing may occur. It can be resolved.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, and FIG. 2 is a diagram for explaining the same. (1) is a disk, (2) is a motor, (3) is a write / read head, (4) is a preceding erase head, (5) is a write / read control circuit, (6) is a data input / output terminal, (7) ) Is an erase current source, (8) is a switch, (9) is a write control input terminal,
(10) is an AND circuit, (11) is a PG, (12) is a delay circuit,
(13) is a flip-flop and (14) is an index output terminal.

Claims (1)

(57) [Claims] 1. A drive unit for rotationally driving a rotary disk type recording medium having a plurality of writing areas, an index signal generating unit for generating an index signal according to the rotation of the recording medium, and writing on the recording medium. A write / read head for performing a read / write operation, an erase head provided at a position preceding the write / read head by a predetermined distance, and an erase head control means for controlling the erase head are provided, and based on the index signal. A magnetic disk drive characterized in that when the write / read head detects that the write area is ahead of the next write area by the predetermined interval, the erase by the erase head is terminated.