JPH01191379A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent a reading error from being generated and to improve operating efficiency by diagnosing off-track quantity to all data heads and setting optimum off-set data to an off-set register, which is equipped in correspondence to the respective data heads, when an off-track is generated. CONSTITUTION:In respective data heads 11-14, more than one auxiliary tracks are prepared and at the time of a power source input and in each constant time, the positioning of the data head is executed by the auxiliary tracks. Then, an auto-track diagnosing circuit 10 is equipped to automatically execute off-set seak operation until recording data can be read. Off-set data, which are used in case of the off-set seak operation, are stored to the respective data heads 11-14 and plural off-set registers 111-114 are equipped to output off-set data F0 to an off-set seak circuit 5 as needed. Thus, the reading error, due to an off-track can be removed and the operation efficiency of a whole system can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device equipped with head positioning means.

[Conventional technology]

Conventionally, this type of magnetic disk drive is capable of retrying the read operation using various methods when successive errors occur during a normal read operation.

For example, the relative positions of the servo surface and multiple data surfaces in the same cylinder are the same in the initial state (at the time of shipment from the factory), but after long-term operation, the spindle may change due to wear of mechanical parts or manufacturing variations. The shaft tilts, causing a relative misalignment between the servo head and the data head (referred to as off-track). For this reason, a situation arises in which the data recorded on the target track cannot be read by normal read operations.

In such a case, an offset command is given from a host device (such as a magnetic disk controller), and the magnetic disk device moves the carriage a predetermined distance forward or backward from the physical track center position (this is called an offset leak operation). ) and the read operation is retried.

FIG. 2 is a block diagram showing the positioning circuit section of the conventional magnetic disk device mentioned above. The conventional example shown in FIG. 2 includes a difference counter 10 that sets offset data U sent from a host device in advance of an offset command using a bus out U2 and a set difference signal U3, and an offset start signal U4. Offset data U is set to the offset leak circuit 30.

and an offset register 20 that sends out. For example, when a read error is detected and it is impossible to correct the repeated errors by retrying the normal read operation,
A method is adopted in which the host device sends an offset command to retry the read operation each time, and the contents of the offset register 20 are reset by the offset reset signal U each time when it becomes possible to continue reading. It is being

Since the above-described conventional magnetic disk device is equipped with only one offset register 20, when a different head is selected, the off-track amount usually differs for each head. For this reason, the offset t-i required for retrying the read operation is different, and each time a different head is selected, an offset command is required from the host device, which is complicated. In addition, if the HDA has already experienced off-track,
() lead disk assembly) for which a read operation is retried using an offset command, the read operation will not be performed every time unless reformatted (track including home address - rewrite for one cycle) is performed. This method has a major disadvantage in that the above-mentioned offset command must be used in operation, which significantly reduces the operational efficiency of the system.

[Purpose of the invention]

An object of the present invention is to provide a magnetic disk device that improves the disadvantages of the conventional example, and in particular almost completely eliminates repeated errors caused by off-track errors, thereby improving the operational efficiency of the entire system. It's about doing.

[Means for Solving the Problems] The present invention includes a head address decoder and readout aging circuit that selectively drive a plurality of data heads, a head movement control means that drives each data head based on a servo surface servo method, The head movement control means includes an offset leak circuit for position control that is attached to the head movement control means, and a magnetic disk control circuit that controls each of these components. The data head is equipped with at least one spare track, and the data head is positioned on the spare track when the power is turned on and at regular intervals. Furthermore, it is equipped with an auto-track diagnostic circuit that automatically performs an offset leak operation until the recorded data can be read out. Furthermore, the structure is such that the offset data used in the offset leak operation is stored in each data head each time, and a plurality of offset registers are provided to output the offset data and the offset leak circuit as necessary. There is.

[Embodiments of the invention]

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

The embodiment of FIG. 1 has a plurality of data heads 1.1□+
A head address decoder 2 and a read/write circuit 3 selectively drive data heads 1.13+1a, and each data head 1. ，
1□+1ff+1a based on a servo surface servo method, and an offset leak circuit 5 for position control attached to this head movement control means 4, each of these components A magnetic disk control circuit 6 is provided to control the magnetic disk. Here, in the servo surface servo method referred to in the head movement control means 4, specifically, servo track information dedicated to track positioning is written only on one surface of a plurality of magnetic disks, and is read out by a servo head 42 to be described later to track the track. Refers to a method of positioning.

Each data head 1. , 1□+1:l+14 is equipped with at least one spare track.

It is equipped with an auto-track diagnostic circuit 10 that positions the data head on a spare track when the power is turned on and at regular time intervals, and automatically performs an offset leak operation until recorded data can be read out. .

Then, the offset data used in the offset leak operation is transferred to each data head 1. ~14
In addition to storing the offset data F as necessary,
A plurality of offset registers 11 that output 0 to the offset leak circuit 5. ．． It is equipped with 11□, 113, and 114.

The magnetic disk control B circuit 6 outputs a read/write control signal 6A to the read/write circuit 3, and outputs a head address signal 6B to the head address decoder 2 to control these operations. It has become.

Multiple offset registers 11□11□, 11! , 11
．． is each data head 1. -14 are provided one by one. These offset registers 11. .

112.113,11. is head address decoder 2
The head select signal H,,H,,H3 which is the output signal of
,H.

Only one item is selected.

For example, when the fourth data head 14 is selected,
Only the fourth offset register 114 is selected. At the same time, the offset register 11 selected by this
．． The offset data F0, which is the output from the circuits 114 to 114, is input to the offset leak circuit 5 as described above.

The off-track diagnostic circuit 10 inputs the output signal Y0 from the read/write circuit 3, outputs an off-track diagnostic control signal J0 to the magnetic disk control circuit 6, and also outputs an offset signal J0 to the offset registers 11° to 114. Outputs data input signal FS.

Offset register 11 to which this offset data human input signal FS is input. ~11. is the offset register set signal R sent from the off-trunk diagnostic circuit at the same time.
8 and R, to set or reset each head 11 to 14.

Each offset register 11. ~11. From the head address decoder 2 to the read/write circuit 3 described above,
The head selector signals H1 to H4 are sent separately to the head selector signals H1 to H4.

The head movement control means 4 inputs the data described above.
14 and this carriage 40
It has a motor 41 that drives the servo head 12 and a servo head 12 mounted on the carriage 40. Further, this head movement control means 4 includes a servo signal demodulation circuit 4 that demodulates a servo signal 42A sent from this servo head 42.
3, a device determination control signal S which inputs the output of this servo signal demodulation circuit 43 and the output of the offset leak circuit 5 described above as an operation command and correction control signal 43A, respectively, and is constituted by the magnetic disk control circuit 6 described above; and a positioning drive circuit 44 that is controlled and operated.

Next, the offset data setting operation in the above embodiment will be explained.

The off-track diagnostic circuit 10 is activated when the power is turned on.

It is designed to operate for a certain period of time and at certain intervals. First, in order to diagnose the off-track amount in advance, the data written in the spare trough at the time of factory shipment (at the time of formatting) is read out, and the head is positioned on the spare track using the off-track diagnosis control signal J0. . Next, a read operation is sequentially performed for all heads, and if a track in which successive errors due to off-track occurs, an offset leak operation is performed and the read operation is retried.

At this time, the data head 11 that required offset operation
,1! , 13 or 14, the corresponding offset register 11. -11. The offset data F at that time
0, and repeat resetting and setting of the offset registers 111 to 114 until the successive errors are corrected,
Each offset register 11. -11, the optimum offset data F0 is set, and the off-track diagnostic operation is completed.

〔Effect of the invention〕

As described above, according to the present invention, when the power is turned on and at regular intervals, all the data is processed using the off-track diagnostic circuit and the data written in advance to the spare track in order to diagnose the amount of off-track. The amount of off-track for the head is diagnosed, and if off-track occurs, the optimal offset data is set in the offset register provided for each data head, so after the off-track diagnosis operation is completed, When reading from a host device,
HD A (llead Di) where off-track has occurred
skAssembly), the offset leak operation is automatically performed when selecting the head, so repeated errors due to off-track do not occur, and therefore the operational efficiency of this system can be improved, which is unprecedented. An excellent magnetic disk device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing a part of a conventional example. 1, ~14...Data head, 2...Decoder, 3
. . . Read/write circuit, 4. Head movement control means, 5. Offset leak circuit, 6. Magnetic disk control circuit, lO. Auto track diagnostic circuit.
11, to 114...Offset register. Patent applicant: Japan Electric Co., Ltd. Agent Patent attorney: Isamu Takahashi Figure 1 Figure 2

Claims (1)

[Claims] (1) A head address decoder and a read/write circuit for selectively driving a plurality of data heads, a head movement control means for driving each data head based on a servo surface servo method, and a head movement control means attached to the head movement control means. In a magnetic disk device having an offset leak circuit for position control and a magnetic disk control circuit for controlling each of these components, each data head is equipped with at least one or more spare track, and the power is turned on. The apparatus is equipped with an auto-track diagnostic circuit that positions the data head on the spare track at regular intervals and at fixed time intervals, and automatically performs an offset leak operation until the recorded data can be read out. A magnetic disk device characterized in that it is equipped with a plurality of offset registers that store offset data to be used for each data head each time, and output the offset data and the offset leak circuit as necessary.