JPS6059572A - Method for controlling retry of magnetic tape device - Google Patents

Abstract

PURPOSE:To prevent frequent generation of reproducing errors by moving the position of a magnetic head finely and vertically to retry the magnetic head for the purpose. CONSTITUTION:When an error is generated in read-out data by a reading circuit 7 for a recording block between the leading end and final end detected through a leading end/final end detecting circuit 13, retry is executed by the prescribed number of times. If a reproducing error is detected, a fine movement commanding circuit 16 is controlled by a control circuit 14, a magnetic head pair 2 is moved finely and vertically through a positioning control circuit 10 and the fine movement is repeated until the reproducing error is removed. Consequently, the positional shear of the magnetic heads from track width is corrected and frequent generation of the reproducing errors is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a retry control method for a magnetic tape device when a reproduction error is detected even after a predetermined number of retries when an information reproduction error is detected.

(b) Background of the technology As the usage of information processing systems becomes more sophisticated and complex, small cartridge-type magnetic tape devices are becoming more and more convenient to handle and carry as backup storage devices, and are also convenient for storing information. Demand is increasing.

The requirements for a backup storage device include:
Although the cost is low, the storage capacity is required to be equal to or greater than that of conventional technology. The serpentine system has been adopted to meet this demand.

What is the serpentine method? When recording information on multiple trunks on a magnetic tape medium, a recording/playback head equivalent to multiple tracks is provided, and the recording/playback head is used in two directions, one for forward direction and one for reverse direction. As a group,
This is a method for recording by running a magnetic tape medium in both forward and reverse directions one track at a time through multiple trunks. Although this method can considerably reduce the cost of installing an expensive magnetic head and recording/reproducing circuit, there is a risk that the quality of reproduced information will deteriorate.

It is desired to realize a magnetic tape device that can meet the above market demands and problems at a low cost and that can ensure quality above a certain level.

(C) Prior Art and Problems As an example of the prior art, a low-cost magnetic tape device employing the serpentine system will be described with reference to the drawings.

Fig. 1 is a configuration diagram of a conventional serpentine magnetic tape device, and Fig. 2 shows an example of recording on a magnetic tape medium using the serpentine method. (A) shows recording example 1, and (B) records example 2. Each is shown below.

In the figure, 1 is a magnetic tape medium, 2 is a magnetic head pair,
3 is a read head, 4 is a write head, 5 is an erase head, 6 is a start/end detector, 7 is a readout circuit, 8 is a bottom positioner, 9 is a stepping motor, 10 is a positioning control circuit, and 11 is a coarse movement instruction circuit. , 12 indicates a write circuit, 13 indicates a start/end detection circuit, 14 indicates a control circuit, and 15 indicates a data block.

Here, P is the width between the trunk and the center of the track, P is the track width on the magnetic tape medium 1, Δ is the positional deviation width of the magnetic head pair 2, a is the forward running direction of the magnetic tape medium 1, and b is the magnetic head pair 2, C shows the magnetic head pair 2 at the normal position on the track, and d shows the magnetic head pair 2 at a position shifted upward by Δ from the normal position on the track. Also, the starting end and ending end on the magnetic tape medium 1 are the magnetic tape medium 1.
This refers to the starting position and ending position of the data block 15 with respect to the forward running direction a of the data block 15.

Magnetic head pair 2 for serpentine method is write head 4
It is composed of two sets, one set being the reading head 3 and the other.

One set is for recording/reproducing in the forward running direction a of the magnetic tape medium 1, and the other set is for recording/reproducing in the reverse running direction. The read head 3 and the write head 4 are the write head 4. viewed from the running direction of the magnetic tape medium 1. They are arranged in the order of the reading head 3, and the written information is immediately reproduced by the reading head 3 to check the written information.

In the serpentine method of information recording, information is recorded from the starting end of a data block 15 that is created so that information is treated as a single unit, and when the starting end/end detector 6 detects that it is the end end, the starting end/end detecting circuit 13 Via control circuit 1
Output to 4. The control circuit 14 switches the magnetic head to be used via a circuit not shown, and outputs information to the coarse movement instruction circuit 11 to instruct movement to the next track. The coarse movement instruction circuit 11 has positioning control circuits 17 & 10.
to position the magnetic head pair 2 to the next track. Once the positioning is completed, the device then travels in reverse from the terminal end to the starting end and starts recording information. The above steps are repeated to record the information on all the tracks by drawing two travel trajectories of the magnetic hend pair shown in FIG. 2(A).

To increase the storage capacity per roll of magnetic tape in the above magnetic tape devices, either (1) increase the recording density, or (2)
) or increase rack density.

Furthermore, in order to increase the track density, accurate positioning of the magnetic node pair 2 is required.

However, the magnetic tape medium 1 is generally
The relative position of the track width P and the magnetic head pair 2 may shift as shown in FIG. 2(B) due to the curvature of the magnetic tape guide (not shown) and the width difference between the magnetic tape medium 1 and the magnetic tape medium 1. Further, even if the positional deviation is adjusted at the starting end or the ending end of the magnetic tape medium 1, the deviation may occur in the middle. In such a case, the output level of the read head 3 is reduced by half, and the resolution of the reproduced signal deteriorates. Furthermore, in the case of the above-mentioned method of recording information by positioning the magnetic head pair 2 on a predetermined track of the magnetic tape medium 1 with increased track density, the relative position between the track width P and the magnetic head pair 2 is small. There is a problem in that misalignment often causes errors as playback errors during information playback.

(d) Purpose of the Invention The present invention aims to provide a new retry control method for a magnetic tape device that eliminates the above-mentioned drawbacks, and in particular, it is an object of the present invention to provide a retry control method for a magnetic tape device that eliminates the above drawbacks. If this causes many playback errors, the position of the magnetic head may be slightly moved in the vertical direction when retrying when a playback error occurs.

An object of the present invention is to realize a retry control method for a magnetic tape device that can correct the positional deviation of a magnetic head with respect to the track width and prevent frequent reproduction errors.

(e) Structure of the Invention The present invention records information after positioning the recording/reproducing head at a predetermined track position at the beginning and end of a data block, which is a physical unit of information recorded on a magnetic tape medium. /A playback error is detected during information playback in the magnetic tape device that performs playback.

If a playback error is detected again after a predetermined number of retries, the recording/playback head position is shifted by a predetermined amount in the vertical direction from the predetermined position of the track, and the retry is performed to adjust the recording/playback head position for the trunk width. This can be achieved by a retry control method for a magnetic tape device, which is characterized by correcting the positional deviation of the reproducing head and making it possible to prevent the reproduction errors from occurring frequently.

(f) Examples of the invention The present invention will be explained below with reference to the drawings.

FIG. 3 shows an embodiment of a serpentine magnetic tape device according to the present invention.

In the figure, 16 indicates a minute movement instruction circuit.

Other symbols are the same as those in FIG. 1 and indicate the same contents.

In this embodiment, a magnetic tape medium 1 for magnetically recording information,
Read head 3. A magnetic head pair 2 consists of two sets, one set being a write head 4, a read head 3 reads information recorded on the magnetic tape medium 1 and outputs it to the read circuit 7, and a read head 3 reads information recorded on the magnetic tape medium 1 and outputs the information from the write circuit 12 to the magnetic tape. A write head 4 records information on the medium 1, an erase head 5 erases previously recorded information on the magnetic tape medium 1 using a drive signal from a write circuit 12 when writing information with the write head 4, and records on a data block 15. a start/end detector 6 that detects signals indicating the start end and end end of the reading head 3; a readout circuit 7 that converts information from the read head 3 so that it can be easily processed by subsequent circuits and outputs the converted information to the control circuit 14; A head positioner 8 that moves the magnetic head pair 2 by driving a stepping motor 9, a stepping motor 9 that drives the head positioner 8 by a signal from a positioning control circuit 10, and a coarse movement instruction circuit 11 or a fine movement instruction circuit 16 for moving the stepping motor 9. a coarse movement instruction circuit 11 that outputs a trunk-to-trunk movement instruction signal to the positioning control circuit 10;
, converts write information from the control circuit 14 so that it can be recorded by the write head 4 and outputs it, and converts signals from the write circuit 12 that outputs signals to the erase head 5 and the start/end detector 6. A micro-movement circuit that outputs an instruction signal to the start/end detection circuit 13 that outputs to the control circuit 14, the control circuit 14 that controls the operation of the entire magnetic tape device, and the positioning control circuit 10 to slightly move the magnetic head pair 2 in the vertical direction. It is composed of an instruction circuit 16.

The operation of this embodiment will be explained with reference to FIG. 2(B) and FIG. 3.

For information writing using the serpentine method, see “(C
) Prior Art and Problems", so it will be omitted here.

As shown in Figure 2 (B), Δ from the trunk's normal position C.
When the reading section 3 reads information at a position d shifted in the -F direction, the read information signal is outputted to the control circuit 14 via the reading circuit 7. Control circuit 14 transfers this information to a host device (not shown). When a host device (not shown) detects a reproduction error from the transferred information, it instructs the control circuit 14 to retry. The control circuit 14 uses a circuit (not shown) to return the magnetic tape medium 1 to a predetermined position and reread it. The reread information is transferred to the host device (not shown) through the same route as before, and when a reproduction error is detected again, the control circuit 14 is commanded to try again in the same way as before. The control circuit 14 repeats the retry. The number of times this is repeated is counted within the control circuit 14, and when it is repeated a predetermined number of times, the control circuit 14 causes the minute movement instruction circuit 16 to
A signal is issued to instruct a minute movement of the position of the pair of magnetic heads 2. The minute movement instruction circuit 16 outputs a minute movement instruction signal to the positioning control circuit 10 to move the magnetic head pair 2 downward from position d by δ. If a retry is made in this state of 0 and there is no reproduction error, reading continues with the state moved by δ. If a reproduction error is still detected, repeat the minute movement. However, the number of repetitions is within the number specified by the control circuit 14. The minute movement width δ is in the range of D>>δ, P/2>δ≧P/4.

(g) Results of the Invention According to the present invention as described above, the position of the magnetic head is slightly moved in the vertical direction when retrying when an information reproduction error is detected, and the position of the magnetic head with respect to the 1-rank width is adjusted. One result is that it is possible to provide a magnetic tape device that can correct misalignment and prevent frequent information reproduction errors.

[Brief explanation of drawings]

FIG. 1 shows the configuration of a conventional serpentine magnetic tape device, FIG. 2 shows an example of recording on a magnetic tape medium using the serpentine method, and FIG. 3 shows an embodiment of the serpentine magnetic tape device according to the present invention. . In the figure, l is a magnetic tape medium, 2 is a magnetic tape pair, 3 is a read head, 4 is a write head, 5 is an erase head, 6 is a start/end detector, 7 is a read circuit,
8 is a navel positioner, 9 is a stepping motor, 10
11 is a positioning control circuit, 11 is a coarse movement instruction circuit, 12 is a write circuit, 13 is a start/end detection circuit, 14 is a control circuit, 15 is a data block, and 16 is a fine movement instruction circuit. 2

Claims (1)

[Claims] In a magnetic tape device, information is recorded/reproduced after the recording/reproducing head is positioned at a predetermined track position at the beginning and end of a data block, which is the physical unit of information recorded on a magnetic tape medium. If a playback error is detected during playback and a playback error is detected again after a predetermined number of retries, the position of the recording/playback head is shifted by a predetermined amount in the vertical direction from the predetermined position of the track and a retry is performed. A retry control method for a magnetic tape device, characterized in that: