JPS6352303A - Erase timing controller for magnetic disk - Google Patents

Abstract

PURPOSE:To allow a wide range for the interval between the magnetic gap of a tunnel erase head and that of a recording/reproducing head and to obtain a small-sized magnetic recorder of high recording density by making the extent, by which the erase start timing is delayed behind the recording start timing, different between existence of the magnetic head in an outside peripheral area and that in an inside peripheral area. CONSTITUTION:The position of a magnetic head 11 in the diametral direction of a magnetic disk is detected and a timing switching signal is generated in a track counter 3 based on track position information, and this timing switching signal is supplied to a timing generating circuit 2. A timing generating circuit 2 is controlled by the timing switching signal, and the extent (value Ton) by which the erase start timing is delayed behind the recording start timing is made different between existence of the magnetic head 11 in the outside peripheral area and that in the inside peripheral area and is set to a value to satisfy prescribed relations.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic disk that is used in magnetic recording devices such as floppy disk drives, and is particularly suitable for use in small-sized, high-density magnetic recording devices. The present invention relates to an erase timing control device.

[Summary of the invention]

The present invention relates to an erase timing control device for a magnetic disk used in a magnetic recording device such as a floppy disk drive, in which erase start timing is adjusted relative to recording start timing in accordance with the position of a tunnel erase head in the radial direction of the magnetic disk. By varying the delay amount to a predetermined value, it is possible to increase the difference in the distance between the magnetic gap of the tunnel erase head and the gap of the recording/reproducing head, realizing a compact, high-density magnetic recording device. It is something that makes it possible.

[Conventional technology]

Conventionally, in a magnetic recording device such as a floppy disk drive device (hereinafter referred to as FDD) where the recording medium can be exchanged,
Generally, during recording, trimming and erasing is performed using a tunnel erase head provided close to the recording/reproducing head to prevent leakage of signals from one adjacent trunk or unerased signals.

FIG. 4 shows an example of a magnetic head used in an FDD.

FIG. 4 shows a front view of the magnetic head, and as shown in FIG.
The recording/reproducing head 31 and the tunnel erase head 3 are provided in close proximity to each other while being separated by an insulator 35.
3 constitute a magnetic head. A magnetic gap 32 is provided in the core of the recording/reproducing head 31, and a magnetic gap 34a is provided in the core of the tunnel erase head 33.
, 34b are provided. The gap distance GL (shown in the figure) between the magnetic gap 32 and the magnetic gaps 34a and 34b is set to a predetermined value so that they do not magnetically interfere with each other. For this reason, by shifting the recording start timing and erasing start timing, and the erasing end timing and playback start timing in a predetermined relationship, the desired area is erased and the desired area is played back. A timing generation circuit is provided.

For example, FIG. 5 shows an example of a track formant of a magnetic disk in an FDD. Assuming that the magnetic disk moves in the direction of the arrow in the figure, in such a format, the ID field 41 and data field 4
3 and start erasing in the area of the gap 42 between
Data field 43 and next sector ID field 4
Erasing must be completed in the gap 44 between 1 and 1, and it is necessary to form a timing that satisfies this condition.

Here, the time from when the recording current to the coil of the recording/reproducing head 31 is stopped at the time of transition from recording to reproduction until the erasing current to the coil of the RAD 33 is stopped during tunnel erase is T. ff (erase off time), and the time from when the recording current flows through the coil of the recording/reproducing head 31 until the erasing current flows through the coil of the tunnel erase head 33 as T and R (erase on time). The relationship between off time, erase on time, and gap interval GL will be explained with reference to FIGS. 6 to 9.

Furthermore, each symbol used in the explanation shall be defined as follows.

GL: Gap distance [μm].

α: Motor rotation fluctuation + light clock deviation.

T07: Erase on time [μs].

Toff: Erase off time [μs].

(2) Circumferential speed (m/s) on the predetermined track.

L,: Number of bytes of ID field 41 = synC + ■D
Address mark + ID + CRC.

Xo: Number of bytes of gap 42.

Ll: Number of bytes of data field 43 - 5 sync+
Data address mark + data + CRC.

XI: Number of bytes of gap 44.

T: Transfer time of 1 byte [μs].

T1: Read recovery time (time until read data settles down after erasing).

FIG. 6 shows the conditions under which continuous recording (multi-sector write) of reading the ID field 41 and writing to the data field 43 for each sector is possible (i.e.,
This shows a condition in which erasing is completed when the gap 32 of the recording/reproducing head 31 passes through the ID field of the next sector.

Perform formatting with the motor rotating at its slowest speed and the light crofter at its shortest (middle track in the diagram).
Assuming that writing is performed in the shaded area in the figure when the motor rotation is the fastest and the write clock is the longest, Toff is limited as shown in equation +1) below.

Here, Y= ((1-α)(Xo+L++X+)) −
((1+cr)(Xo+L++1))... (1)' Figure 7 shows the conditions in which erase-off is performed after passing through the data field 43 and no unerased data is left in the data field 43. . The conditions are most severe when the motor rotation is slowest and the light clock is shortest.
In this case, Toff is limited as shown in equation (2) below.

FIG. 8 shows the CRC whose erase on is ID field 41.
This shows a condition that is performed later and does not erase the CRC in the ID field 41. Lx=X.

- If "l' -v, T ea is limited to 1/ as shown in the following equation (3).

GL-TOfi v(1-cr)<XOTV(1-4
) FIG. 9 shows the conditions under which trimming and erasing can always be performed. If Lz = Xo ・T−v, T O+
'1 is limited as shown in equation (4) below.

T,,V(1+α) <GL +In formula 11, GL and V are not related, so G
Changing the lower limit of L does not affect the condition of Toff, and the condition becomes stricter in equation (2) because GL takes the upper limit value and V ``'' V @ i 6 (
(peripheral speed of the innermost track), so similarly GL
Even if you change the lower limit of T. Does not affect the conditions of ff, therefore, the erase off time TOff
does not need to be changed even if the lower limit of GL is changed unless the upper limit of GL is changed.

In addition, the case where the limit on erase on time T o +t is the most severe according to equations 31 and (4) is shown below (
5) It is shown in the formula.

G L -i-: Lower limit value of G L.

GL□X! Upper limit of GL.

Vsax: peripheral speed at the outermost trunk.

V @1 @: Peripheral speed on the innermost track.

As is clear from equation (5), when the lower limit value of GL is lowered, the upper limit of the erase on time T on becomes a smaller value, and the erase on time T o a is changed as the lower limit value of GL is changed. A need arises.

FIG. 10 shows Tol limited as described above.

It shows an example of the relationship between Toff and gap interval GL, where the vertical axis is T. 7 and Toff, and the horizontal axis shows the value of the gap distance GL. In Figure 10, 5
The TOff and GLO values of the trapezoidal area indicated by 1 are (11
And the conditions of formula (2) are satisfied. Also, T in the triangular area indicated by 53 in FIG. The values of 7 and GL satisfy the condition of equation (5).

However, the on/off timing of the erase current is
Since it is formed by a timing generation circuit consisting of a mono-multi-by-break, a counter circuit, etc., T o ,
, and Toff values vary depending on various conditions, and taking into consideration problems such as crosstalk between the recording/reproducing head 31 and tunnel erase head 33, the values of T6n, Tuft, and Toff that are actually possible are The value of GL is the value in the shaded area 52.54 in FIG. 10, which is even more limited. Generally T02. The upper limit ft of the possible value of GL is determined from the condition, and T on
Lower limit value from the condition! , is determined, and the magnetic head is processed so that the difference in the gap distance GL falls within the range of z, -i.

[Problem that the invention seeks to solve]

However, when trying to realize a compact FDD with high recording density, the absolute value of the gap distance GL becomes small, and T e a
Considering the difference in GL, the actually usable GL difference becomes very small. For this reason, there was a problem in that the processing of the magnetic head was extremely difficult.

Moreover, FIG. 11 shows the circumferential speeds V and T of a predetermined track. The two curves indicate the relationship between T and T in each track.
6 Indicates the upper and lower limits of PL. The area indicated by 55 in FIG. 11 is usable T. It has a value of 7,
In this case, the same T for all tracks. f
It is sufficient to set the value of i. However, if the difference in GL is increased, the relationship shown in FIG. 12 will occur, making it impossible to set the same TOFl value for all tracks. Such a phenomenon also occurs when miniaturization and high density are achieved, and in this case, it is necessary to reduce the difference in GL, which poses a problem.

Therefore, an object of the present invention is to widen the gap between the magnetic gap of the tunnel erase head and the magnetic gap of the recording/reproducing head, thereby realizing a compact magnetic recording device with high recording density. Our goal is to provide 11 timing system devices.

[Means for solving problems]

The present invention relates to a magnetic disk erase timing control device for controlling the erase timing of a tunnel erase head 8 which is provided in the vicinity of a recording/reproducing head 10 in the trailing direction of track extension. A magnetic disk characterized by comprising means 3 for detecting the position of the tunnel erase head 8 in the direction, and means 2 for varying the delay amount of the erasure start timing with respect to the recording start timing according to the output signal of the detection means 3. This is an erase timing control device.

[Effect]

In the track counter 3, the position of the magnetic head 11 in the radial direction of the magnetic disk is detected, a timing switching signal is generated based on the track position information, and this timing switching signal is supplied to the timing generation circuit 2. The timing generation circuit 2 is controlled by a timing switching signal, and the delay amount (T, % value) of the erase start timing with respect to the recording start timing is different when the magnetic head 11 is present in the outer circumferential area and when the magnetic head 11 is present in the inner circumferential area. 11 exists, and is set to a value that satisfies a predetermined relationship.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of the present invention, and in the first part, 2 is a timing generation circuit. The timing generation circuit 2 is composed of, for example, a mono multivibrator or the like, and forms an erasure timing signal by switching the delay amount of the erasure start timing with respect to the recording start timing in response to a timing switching signal from the track counter 3. It is.

Further, in FIG. 1, a broken line 11 indicates a magnetic head. As shown in FIG. 2, the magnetic head 11 is provided with a recording/reproducing head 10 and a tunnel erase head 8 adjacent to each other and separated by an insulator 14. A magnetic gap 12 is provided in the core of the recording/reproducing head 10, and magnetic gaps 13a and 13b are provided in the core of the tunnel erase head 8. The gap distance GL (shown in the figure) between the magnetic gap 12 and the magnetic gaps 13a and 13b is set to a predetermined value so that they do not magnetically interfere with each other.

A recording timing signal is supplied to an input terminal indicated by 1 in FIG. 1, and this recording timing signal is supplied to the timing generation circuit 2 and also to the recording circuit 9. For example, when the recording timing signal is set to a high level, a recording current is generated in the recording circuit 9.

This recording current is supplied to the recording/reproducing head 10, and writing is performed on the data field of the magnetic disk. Note that in FIG. 1, a circuit related to a reproduction system is omitted.

In addition, an index track (track number 00 on the outermost trunk) is connected to terminal 4 from the system controller, etc.
The detection signal is supplied to the track counter 3 via the terminal 4. For example, when an index track is detected, the detection signal is set to high level and the count value of the track counter 3 is reset.

A step signal is supplied to the terminal 5, which becomes, for example, a high level every time the magnetic head 11 crosses one track.
A step signal is supplied to the track counter 3 via a terminal 5. At the same time, a detection signal in the moving direction of the magnetic head 11 is supplied to the terminal 6, for example, a detection signal that becomes high level when moving toward the inner circumference and becomes low level when moving toward the outer circumference. The signal is supplied to the track counter 3 via.

The trunk counter 3 is configured to amplify and count the rise of the step signal when the detection signal in the moving direction of the magnetic head 11 is set to high level, and to count down the rise of the step signal when the detection signal is set to low level. has been done. The magnetic head 11 in the radial direction of the magnetic disk is determined by the count value of the track counter 3.
The position of the truck is detected and a timing switching signal is generated in the trunk counter 3 based on this track position information. For example, when it is determined that the magnetic nodal 11 exists in the outer circumferential region from the outermost trunk to a predetermined track that is approximately in the radial center of the magnetic disk, the timing switching signal is set to a low level. In addition, the recording head 11
If it is determined that the timing change signal exists in the inner circumferential area from the predetermined track approximately at the center to the innermost circumferential track, the timing switching signal is set to a high level. The timing switching signal generated by the track counter 3 is supplied to the timing generation circuit 2.

In the timing generation circuit 2, the delay amount of the erase start timing with respect to the recording start timing is switched according to the timing switching signal, and an erase timing signal is formed. Specifically, the value of the above-mentioned erase on time T on is different depending on whether the magnetic head 11 is present in the outer circumference side region or the Eff magnetic head 11 is present in the inner circumference side region, and the predetermined relationship is established. It is assumed that the value is within the satisfying range.

Figure 3 shows erase on time T. Indicates the range of possible values for 1. In FIG. 3, the upper solid curve indicates T at the circumferential speed ■ corresponding to each trunk. 1, and the lower solid curve indicates T6 at the circumferential speed ■ corresponding to each track.
．． , indicates the lower limit of . In FIG. 3, the value in the area indicated by 16 is the value of T a b set when the magnetic head 11 exists on the inner circumference side, and the value in the area indicated by 17 is the value for the magnetic head 11 on the outer circumference side. T set when the throat 11 exists. , is taken as the value of .

A predetermined time (T
An erase timing signal that rises to a high level, for example, with a delay of 0, ) is supplied from the timing generation circuit 2 to the erase circuit.

When the erase timing signal is set to high level, the erase circuit 7
An erase current is formed at . This erase current is supplied to the erase head 8, and the data field in which data was written just before is surely trimmed and erased.

In one embodiment of the present invention, a configuration has been described in which the value of T o ++ is changed at a track approximately at the center in the radial direction of the magnetic disk, but the value of T o ++ is changed at a plurality of locations.

The value of 7 may be changed to satisfy a predetermined relationship.

〔Effect of the invention〕

In this invention, the position of the magnetic head in the radial direction of the magnetic disk is detected by the track counter, a timing switching signal is generated based on the track position 'tftH, and this timing signal is supplied to the timing generation circuit. The timing generation circuit is controlled by a timing switching signal, and the delay amount (To) of the erase start timing with respect to the recording start timing is different when the magnetic head is present in the outer circumferential area and when the magnetic head is present in the inner circumferential area. and is made variable, and is set to a value that satisfies a predetermined relationship.

Therefore, according to the present invention, even when the difference in recording and erasing timing is set to the same value as in the conventional case, the gap interval G
A sufficient range of L can be ensured. Therefore, there is no need to increase the processing precision of the magnetic head, and it is possible to realize a sufficiently compact high-density magnetic recording device by extending conventional technology.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of this invention, FIG. 2 is a front view of a magnetic head in an embodiment of this invention, and FIG. 3 is a route diagram used to explain the operation of an embodiment of this invention. , FIG. 4 is a front view of the borosilicate head as an example, FIG. 5 is a route map of the track format as an example, and FIGS.
FIG. 12 is a route diagram used to explain a conventional magnetic disk erasure timing control device. Explanation of main symbols in the drawings 2: Timing generation circuit, 3rd rank counter,
8; tunnel erase head; 10: recording/reproducing head; 12, 13a, 13b: magnetic gap. Agent Patent Attorney Tadashi Sugiura Chiryota - Soto Figure 3 Boundary View Room Figure 5 Figure 6 3331

Claims (1)

[Scope of Claims] A magnetic disk erase timing control device that controls the erase timing of a tunnel erase head that is disposed trailing in the direction of track extension and close to a recording/reproducing head, comprising: a diameter of the magnetic disk; Erasing a magnetic disk, comprising: means for detecting the position of the tunnel erase head in the direction; and means for varying the delay amount of the erase start timing with respect to the recording start timing in accordance with the output signal of the detecting means. Timing control device.