JPH04310606A - Magnetic tape device - Google Patents

Abstract

PURPOSE:To reduce the error generation probability by performing normally the data recording and the error detection even when the dust is stuck to a reading head and a writing head. CONSTITUTION:Along a forward direction, two writing heads WE1 and WE2 and two reading heads RE1 and RE2 are provided, and these writing heads WE1 and WE2 and reading heads RE1 and RE2 are alternatively used respectively. It is judged at which of the reading head or the writing head the error cause exists, by the coincidence/non-coincidence of two reading signals from the reading heads RE1 and RE2 when the error in the recording condition is detected and in accordance with the judged result, the reading head or the writing head is switched from the head during using to other head. Then, even when the dust is stuck to the reading head or the writing head, the data recording and the error detection can be normally performed and the reliability of the action of the magnetic tape device can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape device, and more particularly to a magnetic tape device having a mechanism for checking the recording state by read-after-write operations.

0002

[Prior Art] Conventionally, a serpentine type magnetic tape device has a structure in which a write head is provided at the front in the running direction of the tape, and a read head is provided at the back.During data recording, the write head records data on the tape. However, a method (read-after-write) is adopted in which it is determined whether or not recording has been performed correctly by reading out the recorded signal with a read head. If the data cannot be recorded normally, an error retry is performed in which writing of the same data is executed up to the specified number of times.

[0003] Furthermore, when reading recorded data,
A read head is used to perform a reproduction operation, and if the reproduction cannot be performed correctly, an error retry is performed in which the same part is read multiple times.

However, in the past, if dust or the like adheres to the write head gap, space loss occurs (a phenomenon in which a gap occurs between the tape and the head, making it impossible for the write current output to correctly contribute to magnetic flux changes on the tape). ) occurs, the read-after-write signal amplitude becomes small and normal recording is no longer possible. In this case, recording failures occur such as, for example, the start signal of the data recording area cannot be detected, the signal amplitude becomes less than a specified value, or an error occurs in the CRC check.

[0005] Furthermore, if dust adheres to the gap of the read head, the read data check of the read-after-write operation may determine that the data could not be recorded correctly, even though the tape was recorded normally. There is a problem that the recording operation is repeated again.

[0006]

Problems to be Solved by the Invention Conventionally, there has been a problem in that dust adhering to the read head or write head hinders normal data recording and error detection.

[0007] The present invention was made in view of the above points, and it is possible to perform data recording and error detection normally even if dust is attached to the read head or write head, thereby improving operational reliability. The purpose is to provide a high quality magnetic tape device.

[0008]

[Means and operations for solving the problems] A magnetic tape device according to the present invention includes a plurality of write heads and read heads arranged sequentially along the running direction of a magnetic tape, and data recording from among the plurality of write heads. a write head selection means for alternatively selecting a write head to be used for the read head selection means; a read data selection means for alternatively selecting read data read from each of the plurality of read heads; means for inspecting a recording state using the read data read from the plurality of read heads; means for detecting coincidence/mismatch of the read data read from each of the plurality of read heads; and means for detecting an error in the recording state by the inspection of the recording state. In this case, the apparatus is characterized by comprising means for switching either the write head or the read head to another write head or read head, respectively, depending on whether the read data match/mismatch.

This magnetic tape device is provided with a plurality of write heads and read heads, and each of the write heads and read heads is used selectively. When an error in the recording state is detected, it is determined whether the cause of the error is in the read head or the write head based on the match/mismatch of read data from multiple read heads. The head being used is switched to another head. Therefore, even if dust is attached to the read head or write head, data recording and error detection can be performed normally, and the reliability of the operation of the magnetic tape device can be improved.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a magnetic tape device according to an embodiment of the present invention. This magnetic tape device is a serpentine device that performs read-after-write operations, and includes a magnetic head section 11, a write switching circuit 12, a write circuit 13, and a write head switching circuit 14.
, first and second read signal amplification circuits 15 and 16, first and second read output detection circuits 17 and 18, a read switching circuit 19, a read head switching circuit 20, and a control section 21.

The magnetic head section 11 includes two write heads WE1 and WE2 arranged in front along the forward running direction of the magnetic tape, and two read heads RE1 and RE2 arranged behind them. , two write heads W01 and W02 are arranged in front along the reverse running direction, and two read heads R01 and R02 are arranged behind them.

In this magnetic head section 11, forward write heads WE1, WE2 and read head RE1 are used to record/reproduce even-numbered tracks of the magnetic tape.
, RE2 are used, and write heads W01, W02 and read heads R01, R02 in the reverse direction are used for recording/reproducing on odd-numbered tracks.

[0014] The read heads RE1 and RE2 are used for checking recorded data by read-after-write operation during recording operations on even-numbered tracks, and are used for reading data from the tape during data reading operations on even-numbered tracks. Ru.

Similarly, the read heads R01 and R02 are
During the recording operation of odd-numbered tracks, it is used to confirm recorded data by read-after-write operation, and during the data reading operation of odd-numbered tracks, it is used for reading data from the tape.

The write heads WE1 and WE2 are used for recording data on the tape during recording operations on even-numbered tracks. In addition, light heads W01, W0
2 is used for recording data on the tape during recording operations on odd-numbered tracks.

The write switching circuit 12 selectively selects two write heads provided in each of the forward and reverse directions according to the write head switching circuit 14. The write circuit 13 is a circuit that controls a current flowing to a selected write head based on a write signal waveform whose code has been converted by a circuit not shown.

The write head switching circuit 14 is composed of a register, and this register contains selection information specifying which of the two write heads is used in each of the forward and reverse directions. is set by the control unit 21.

The read signal amplification circuits 15 and 16 are circuits that amplify read signals from two read heads in the forward and reverse directions, respectively, and amplify minute currents read from the tape.

That is, the read signal amplification circuit 15 amplifies the read signal from the read head RE1 during recording/reproducing in the forward direction, and amplifies the read signal from the read head R01 during recording/reproducing in the reverse direction. Further, the read signal amplification circuit 16 amplifies the read signal from the read head RE2 during recording/reproducing in the forward direction, and amplifies the read signal from the read head R02 during recording/reproducing in the reverse direction.

The read output detection circuits 17 and 18 are circuits that detect the amplitude of the read signal from the read signal amplification circuits 15 and 16 (the actual amplitude within a certain period of time from the beginning of each block), respectively.

The read signal switching circuit 19 selects which read signal from the read signal amplification circuits 15 and 16 is to be used as the actual read signal. The selected read signal is sent to the host device via the control unit 21.

The read head switching circuit 20 is composed of a register, and selection information specifying which read signal from the read signal amplification circuits 15 and 16 is to be used is set in this register by the control unit 21. be done.

The control section 21 controls the recording/reproducing operation of this magnetic tape device in accordance with instructions from the host device, and checks the recording state by read-after-write operation when recording data.

In checking the recording state, when the control section 21 determines that dust has adhered to the read head, it switches the read head by changing the selection information of the read head switching circuit 20. Further, when it is determined that dust has adhered to the write head, the write head is switched by changing the selection information of the write head switching circuit 14. Figure 2
shows the operating procedure of such error processing executed by the control unit 21.

Here, the write head WE1 (the first write head in the forward direction) is used to execute the recording operation on the magnetic tape, and the read head RE1 (the first read head in the forward direction) is used to perform the read-after operation. Assume that writing (an operation to check whether recorded data was recorded correctly) is being performed.

First, during the recording operation (writing process), the control unit 21 first checks whether the writing process of the data length requested by the host device has been completed (step S11).

If it is not completed, the recorded data is subsequently recorded on the tape via the write circuit 13, the write switching circuit 12, and the write head WE1, and the recorded data is transferred to the read head RE1 and the read signal amplification circuit. 15
, read out via the read switching circuit 19 (steps S12, S13).

Next, the control unit 11 performs a CRC check (cyclic redundancy check) on the read signal from the read switching circuit 19 in order to confirm the recording state, and thereby determines whether or not the data has been recorded normally. (Step S13).

[0030] If the data is not recorded normally,
In order to determine whether the cause is a space loss in the write head or read head or another reason, the control unit 11 checks the signal amplitude of the read signal (step S14).

In checking the signal amplitude of the read signal, it is determined whether the effective amplitude output from the read output detection circuit 17 exceeds a specified value. If the signal amplitude exceeds the specified value, the current during recording was sufficient, but data errors have occurred due to other causes, and if the signal amplitude is below the specified value, either recording or playback may not be possible. It is determined that there was a problem (reduction in amplitude due to space loss between the read head and the magnetic tape or space loss between the write head and the magnetic tape).

Next, the control section 11 controls the read signal amplification circuit 15, in order to determine whether the cause of the error in the recorded data is on the write head side that is performing data recording or on the read head side. The read signals from No. 16 are compared (step S15).

If the read signals are equal, it is determined that a space loss has occurred on the write head side, and if the read signals are different, it is determined that a problem has occurred on the read gap side.

When the read signals are equal, that is, when it is determined that there is a problem on the write head side, the control section 11 changes the selection information of the write head switching circuit 14,
Light head WE1 which I used until now
to another write head WE2 (the second write head in the forward direction) (step S16).

Furthermore, if the read signals do not match, that is, if it is determined that there is a problem on the read head side, the control section 11 changes the selection information of the read head switching circuit 20, and switches the read head that has been used until now. The current read head RE1 is switched to another read head RE2 (second read head in the forward direction) (step S1).
7).

After switching between the read head and the write head in this manner, the control unit 11 prepares for rewriting, such as determining the data content to be recorded next (step S18), and then starts the writing process. Re-execute (steps S12 to S17).

On the other hand, if it is determined in step S14 that the amplitude of the read signal is normal, the process proceeds to step S1 without switching the read head or write head.
8 is prepared for rewriting, and the writing process is re-executed.

As described above, in this embodiment, two write heads WE1 and We2 are arranged along the forward direction.
, and two read heads RE1, Re2 are provided, and these write heads WE1, We2 and read heads RE1, Re2 are used alternatively, respectively. When an error in the recording state is detected, read head RE1
, it is determined whether the cause of the error is in the read head or the write head based on the match/mismatch of the two read signals from Re2, and depending on the result of the determination, the read head or write head is switched from the currently used head to another head. can be switched to

Therefore, even if dust is attached to the read head or write head, data recording and error detection can be performed normally, and the reliability of the operation of the magnetic tape device can be improved.

In this embodiment, error handling during data recording has been explained, but the probability of error occurrence can also be reduced during data reproducing operation by selecting the read head with a larger signal amplitude during reproducing. .

[0041]

As described above, according to the present invention, data recording and error detection can be performed normally even if dust is attached to the read head or write head.
Operation reliability can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic tape device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an error handling operation during data recording in the same embodiment.

[Explanation of symbols]

11...Magnetic head unit, 12...Write switching circuit, 14
...Write head switching circuit, 15, 16... Read signal amplification circuit, 17, 18... Read output detection circuit, 19... Read signal switching circuit, 20... Read head switching circuit, 21... Control section.

Claims (1)

[Claims] 1. A plurality of write heads and read heads sequentially arranged along the running direction of a magnetic tape, and write head selection for selectively selecting a write head to be used for data recording from among the plurality of write heads. means and
read data selection means for selectively selecting read data read from each of the plurality of read heads;
means for inspecting the recording state using the read data selected by the read data selection means; means for detecting coincidence/mismatch of the read data read from each of the plurality of read heads; A magnetic tape characterized by comprising means for switching one of the write head or read head to another write head or read head, respectively, depending on whether the read data matches or mismatches when a state error is detected. Device.