JPH0380465A - Index signal output system for magnetic disk device - Google Patents

Abstract

PURPOSE:To process data in high speed by executing the time delaying, recording an index pattern at a part of the data track, and outputting the index signal with a corresponding timing to the index pattern respectively each magnetic head. CONSTITUTION:A shift resister 20 shifts the index signal (a) with a delay clock signal (k) and outputs (n) pieces of delay index signals. By the head number held at a latch circuit 21 selector 22 selects and outputs the delay index signal corresponding to the head number from (n+1) delay indexes output of the resistor 20. By a clock (k) the pulse width generating circuit 24 samples the selecting index (l) from the selector 22 and outputs an outside index signal (h) of any pulse width. The signal (h) is recorded in a part of the data track as an index pattern. In such a manner, the read/write of the data can be accurately processed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an index signal output method for outputting an index signal indicating the start of a data track on a magnetic disk in a magnetic disk device.

[Conventional technology]

FIG. 3 is a diagram showing the configuration of a conventional magnetic disk device.
2 is a magnetic disk located on the magnetic disk 1 for recording and reproducing information. 3 is a spindle motor that holds the magnetic disk 1 and rotates it at a constant speed. 4 is a carriage, and the magnetic head 2 is
is held and moved in the radial direction on the magnetic disk 1. Reference numeral 5 denotes a voice coil motor that provides driving force for moving the carriage 4. A base 6 holds the spindle motor 3, carriage 4, and voice coil motor 5. Reference numeral 7 denotes an index detection circuit, which generates an index signal every time the magnetic disk rotates once.

Next, the operation will be explained.

Storage and reproduction of information in a magnetic disk device is performed by a plurality of magnetic heads 2 facing a plurality of magnetic disks 1, respectively. The position of the magnetic head 2 is controlled by position information recorded in advance on at least one surface of the magnetic disk l.

FIG. 4 is a diagram showing the magnetic disk 1, and 8 indicates a data track on the magnetic disk 1. Recording/reproduction data is opposed to any one magnetic head selected from a plurality of magnetic heads 2. It is configured on a magnetic disk 1. ? j!
Writing and reading are performed on any one of the several concentric data tracks 8.

FIG. 7 shows a block diagram of a conventional magnetic disk device.
In FIG. 7, IO is a head drive circuit that amplifies read data from a data head 2a and a read/write circuit 11.
Send to. Also, during writing, a write current is caused to flow through the data head 2a based on data from the read/write circuit 11.

The read/write circuit 11 is connected to a read/write interface circuit 12 and converts read/write data. The read/write interface circuit 12 sends and receives data to and from a host system (not shown). Reference numeral 13 denotes a head selection circuit which selects any one of the plurality of data heads 2a based on the head selection signal f received via the read/write interface circuit 12.

A servo amplifier 14 amplifies servo data obtained from the servo head 2b. A position detection circuit 15 is connected to the servo amplifier 14 and the head drive circuit 10, and detects the radial position of the servo head 2b and the head 1' head 2a.

A position control circuit 16 sends an actuator movement signal to the voice coil drive circuit 17 to control the data head 2a selected by the output of the position detection circuit 15 on the data trunk 8. Further, the selected data head 2a, which has the function of moving the magnetic head 2 on the magnetic disk l in the radial direction and positioning it on an arbitrary data track 8 by a seek command signal e from a host system (not shown), is moved to the data track. 8, a seek combination signal g is sent out as a positioning completion signal. Details of head positioning directions by the servo head and data head are shown in, for example, previously filed Japanese Patent Application No. 58-221484. 7
is an index detector which detects the index recorded on the servo pattern and outputs an index signal a once per rotation. FIG. 8 shows the index signal and data timing of a conventional magnetic disk device for reference.

For reference, FIG. 9 shows the timing of data write in a conventional magnetic disk device.

In a conventional magnetic disk drive, the data structure of all data heads is based on the index signal a, and the address section and the data section are recorded starting from the position of the index signal a.

In this manner, in the conventional magnetic disk device, when receiving the seek command signal e, the seek combination signal g is set to LOW, the head is moved, and when the movement is completed, the seek combination signal is set to HIGH. Next, when the head select signal f is received, the seek comp signal g is set to [, ow for a certain period of time again, and the positioning of the data head 2a is executed. Data read/write operations are prohibited while the head is moving, and the seek combination signal g
It is executable only when is Hlgh.

[Problem to be solved by the invention]

Conventional magnetic disk drives are configured as described above, so when continuously reading or writing data up to head HoNHn, there is time for head switching and head positioning, so the head data after switching is Unable to read/write the beginning continuously, 1
I had to wait for rotation. This poses a problem, particularly when initializing data on all heads and all data tracks, a large amount of dead time is required for waiting for rotation.

In order to solve the above-mentioned problems, a disk control device disclosed in Japanese Patent Application Laid-Open No. 180964/1983 is known. This prior art uses a first counter that counts up to a certain value from the input of an index detection signal in order to eliminate the waiting time after switching the head number when processing multiple tracks continuously while switching the head number. A second counter is provided that counts the count completion output of the first counter up to a certain value using the head number as an initial value.For example, if one counter malfunctions, the output of the index signal is This causes problems such as timing shifts and data read/write processing cannot be performed accurately.

This invention was made to solve the above-mentioned problems, and is an indexing system for magnetic disk devices that can minimize the rotational wait due to head switching and perform data read/write processing accurately and at high speed. The purpose is to obtain a signal output method.

[Means to solve the problem]

The index signal output method according to the present invention switches the index signal indicating the start of the data track 8 on the magnetic disk 1 according to the selected head number so that there is no delay in read/write processing due to waiting for rotation of the magnetic disk 1. It is characterized by an index delay circuit 18 having a function of performing a time delay and recording an index pattern on a part of the data track 8, and outputting an index signal for each magnetic head 2 at a timing according to the index pattern. That is.

[Effect]

The index delay circuit 18 switches the index signal according to the selected head number, performs a time delay so that there is no delay in read/write processing due to waiting for rotation of the magnetic disk 1, and prints an index pattern on a part of the data track 8. Record.

Therefore, the index signal is output for each magnetic head 2 at a timing corresponding to the index pattern.

〔Example〕

FIG. 1 is a block diagram of a magnetic disk device employing an index signal output method according to an embodiment of the present invention. In FIG. 1, components corresponding to those shown in FIG. 7 are designated by the same reference numerals, and their explanations will be omitted. In FIG. 1, the index signal 18 is switched depending on the head number selected by the head selection circuit 3 to time-delay the index signal so that there is no delay in read/write processing due to waiting for rotation of the magnetic disk 1, and the data track 8 ( This is an index delay circuit which has a function of recording an index pattern in a part of the circuit (see FIG. 4).

FIG. 5 is a block diagram of the index delay circuit. In FIG. 5, a shift register 20 shifts the index signal a input from the index detection circuit 7 using a delay clock k, and outputs n delayed index signals. 21 is a latch circuit and head selection circuit 13
The head number output from the head is latched and held by the delayed clock signal k. 22 is a selector which selects the shift register 2 according to the head number held in the latch circuit 21.
A delay index signal corresponding to the head number is selected from n+1 delay index outputs from 0 and output.

23 is a delay clock circuit which divides the frequency of clock 1 synchronized with index signal a and outputs delayed clock k. 24
is a pulse width monitoring circuit, which is composed of an integrated circuit such as, for example, a product name 74L3123, which samples the selection index l outputted from the selector 22 using a delay clock k and outputs an external index signal H having an arbitrary pulse width. This external index signal is recorded as an index pattern on a part of the data track 8, and thereafter the external index signal is outputted according to the recorded index pattern.

Next, the operation will be explained. FIG. 6 shows a time chart showing the operation of the index delay circuit 18, and FIG. 2 shows the read/write timing in the magnetic disk device according to this embodiment.

In FIG. 6, if the period of the delay clock is indicated by t2, the delay time from index signal a, then the delay time T7 from index signal a for head number n is T,
”t, xn+t.

Estimated positioning time due to head switching, 1° width 3m
It is about s. t2 is determined by clock l,
When tzA-Q is 5 m, To = 0.5 ms.

TI=3.5ms, Tt=6.5ms.

Referring to FIG. 2, the read/write timing of the magnetic disk device according to this embodiment will be explained. When the seek operation by the seek command signal e is completed and the seek combination signal g is sent out, the corresponding magnetic head is selected by the head select signal f. If the head HO is selected at this time, a delay index corresponding to the head HO is output to the external index h, and data reading/writing is performed.

Next, when head H1 is selected, a delay index signal corresponding to head H1 is output. The index of head H1 lags the index of head HO by a delay time t, so even if there is a head switch after writing or reading one track of head HO data, the data of head H1 can be read with almost no waiting time. It is possible to read and write. This is particularly effective when writing and reading data for all heads.

〔Effect of the invention〕

As described above, according to the present invention, the index signal is switched depending on the selected head number, and the index pattern is applied to a part of the data track by time delaying so that there is no delay in read/write processing due to waiting for rotation of the magnetic disk. Since the index signal is outputted at a timing according to the above index pattern for each magnetic head, it is possible to shift the start of the data track corresponding to each magnetic head. The rotational wait is minimized, the access time of the magnetic disk device is shortened, and data read/write processing can be performed accurately and at high speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic disk device employing an index signal output method according to an embodiment of the present invention, and FIG.
The figures are timing charts for explaining the read/write timing in this embodiment, FIG. 3 is a configuration diagram of the magnetic disk device, FIG. 4 is a plan view of the magnetic disk, and FIG.
The figure is a block diagram of the index delay circuit in Figure 1, Figure 6 is a timing chart for explaining the operation of the index delay circuit, Figure 7 is a block diagram of a conventional magnetic disk drive, and Figure 8 is a block diagram of the index delay circuit. FIG. 9 is a timing chart for explaining the timing of index signals and data in the conventional example. FIG. 9 is a timing chart for explaining the timing of reading and writing data in this conventional example. 1... Magnetic disk, 2... Magnetic head, 8... Data track, 18... Index delay circuit.

Claims (1)

[Claims] In a magnetic disk device equipped with a plurality of magnetic disks for recording information and a magnetic head for recording and reproducing information on these magnetic disks, an index signal indicating the start of a data track on the magnetic disk is selected. An index delay circuit is provided which has a function of recording an index pattern on a part of the data track by switching the head number according to the head number and recording an index pattern on a part of the data track by performing a time delay so that there is no delay in read/write processing due to waiting for rotation of the magnetic disk. An index signal output method for a magnetic disk device, characterized in that an index signal is output for each magnetic head at a timing according to the index pattern.