JPH02122404A - Write data supervising device for magnetic recording - Google Patents

Abstract

PURPOSE:To detect the omission of a write pulse in the middle of a process in units of a pulse by comparing a write data pulse column with a flyback pulse column generated with a current change flowing through a magnetic head in units of a pulse. CONSTITUTION:When the pulse corresponding to a pulse A2 in the pulse column of write data A is omitted in the middle of the process, for a write current I1, since the change corresponding to the pulse A2 is not generated, a signal C3 of a flyback voltage signal C is omitted as well, and a pulse d2 of a flyback pulse D is omitted in the same way. In such a case, since an output (e) of a first flip flop 3 is not reset by the flyback pulse d2, a high level '1' is maintained until a next flyback pulse d3. Consequently, an output (a) of a second flip flop 4 is set at the high level '1' at the time of the arrival of a pulse A3 of the write data A. In such a way, by comparing the pulse column of the write data A with the pulse column of the flyback pulse (d), the omission in units of a pulse can be detected.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a write data monitoring device for magnetic recording.

[Conventional technology]

Conventionally, this type of write data monitoring device detects the flyback voltage of the magnetic head and monitors the time interval in which the flyback voltage occurs. A method has been adopted in which an alarm is output if a flyback voltage is not generated within a predetermined time.

[Problems to be Solved by the Invention] However, since the conventional write data monitoring device monitors the time interval of the flyback voltage as described above, it is difficult to solve the problem of bit-by-bit loss of write data. There was an inconvenience that it could not be detected at all.

[Object of the Invention] The object of the present invention is to improve the inconveniences of the conventional example, and in particular to monitor the pulse train of the write data for dropouts in the minimum pulse unit, thereby improving the reliability of the recorded data. It is an object of the present invention to provide a write data monitoring device for magnetic recording that can be used to monitor data.

[Means to solve the problem]

In the present invention, a flyback detection circuit detects a back electromotive force that changes according to write data and is generated when the power supply of the magnetic head changes; a first flip-flop that is set by the write data and reset by the output of the flyback detection circuit; The second flip-flop latches the output state of the first flip-flop when data arrives and uses the output as an alarm signal.

This aims to achieve the above-mentioned purpose.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The embodiment shown in FIGS. 1 and 2 includes a flybank detection circuit 2 that changes according to write data and detects a back electromotive force generated when the current of the magnetic head l changes, and a flyback detection circuit that resets with the write data. 2, and a second flip-flop 4 that latches the output state of the first flip-flop 3 when write data arrives and uses the output as an alarm signal. Flyback detection circuit 2
are connected to the magnetic head 1 in parallel.

Write data A is applied to the magnetic head 1 via a write circuit 10.

To explain this in more detail, write data A to be recorded on a magnetic recording medium and a write enable signal B that becomes active during data writing are input to the write circuit 10, and its output is connected to the magnetic head 1 and the flyback detection circuit 2. be done. The output of the flyback detection circuit 2 is connected together with the write enable signal B to the reset terminal of the first flip-flop 3 via an OR circuit 11. Write data A is connected and input to the trigger terminal Re= of the first flip-flop 3. The output terminal of the first flip-flop 3 is connected to the data terminal of the second flip-flop 4. Write data A is input to the trigger terminal of the second flip-flop 4, and write enable signal B is input to the reset terminal. The output terminal of this second flip-flop 4 is connected to a write circuit 10, and its output is sent to a control circuit (not shown) as an alarm signal a.

Next, the operation of the above embodiment will be explained.

When data is not written, the write enable signal B is at a low level "0", and the write circuit 10 is in an inactive mode. At the same time, the first and second flip-flops 3 and 4 are also reset, so the outputs e and a of the first and second flip-flops 3.4 are fixed at low level "0".

When writing data, the write enable signal B becomes a high level "1" and the write circuit 10 enters the operating mode. Simultaneously first and second flip-flop 3.4
Since the reset is also released, it enters the operating mode.

Here, as shown in FIG. 2, when each pulse for write data arrives in order of AI, Az, and Ax, the write current 11 flows to the magnetic head 1 according to the pulses At, At, and A3. As a result, the flyback voltage signal C is applied to both terminals of the magnetic head 1 as CI+2+C3...
(The flyback voltage signal f has the opposite polarity waveform of the flyback voltage signal C).

These flyback voltage signals c and f are waveform-shaped by the flyback detection circuit 2, and the flyback pulse d is L,
The signals are transmitted in the order of dz, dz, and so on.

The output e of the first flip-flop 3 is the write data A
It is set by the flyback pulse d and reset by the flyback pulse d. For this reason, pulse e is set at the rising edge of A, and reset at d.

Thereafter, they occur in the order of eZ+e3...

The output a of the second flip-flop 4 is always at a low level "0" because the state of the output e of the first flip-flop 3 is latched when the write data A arrives.

Next, a case will be described in which the pulse corresponding to A2 in the pulse train for write data is lost midway.

Write current ■1 does not change corresponding to A2 as shown by the broken line, so 03 is missing in the flyback voltage signal C as shown by the broken line, and d2 is also missing in the flyback pulse d. .

In this case, since the output e of the first flip-flop 3 is not reset by the flyback pulse d2, it maintains the high level "1" until the next flyback pulse d3. Therefore, the output a of the second flip-flop 4 becomes high level "1" when the pulse A3 of the write data A arrives.
is set to

That is, by comparing the pulse train of the write data A and the pulse train of the flyback pulse d, it is possible to detect the omission of each pulse.

As a result, if a pulse is missing in part of the input write data A, the write circuit 10 is immediately set to a non-operating mode, and at the same time, the control circuit is notified of an alarm state.

〔Effect of the invention〕

As described above, according to the present invention, since the write data pulse train and the flyback pulse train generated by the change in the current flowing through the magnetic head are compared pulse by pulse, the write pulse train is Therefore, it is possible to provide an unprecedented and excellent written data monitoring device for magnetic recording that can detect an intermediate omission of data, thereby greatly improving the reliability of recorded data.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a waveform diagram showing the operation of each part in FIG. 1. 1...Magnetic head, 2...Flyback detection circuit,
3.4...Flip-flop. Patent applicant: Japan Electric Co., Ltd. Agent: Patent attorney: Takahashi

Claims (1)

[Claims] (1) A flyback detection circuit that changes according to write data and detects a back electromotive force generated when the power supply of the magnetic head changes; a first flip-flop that is set by the write data and reset by the output of the flyback detection circuit; A write data monitoring device for magnetic recording, comprising a second flip-flop that latches the output state of the first flip-flop when data arrives and uses the output as an alarm signal.