JPH07244933A - Method of initializing digital information recording medium - Google Patents

Abstract

PURPOSE:To provide a method of initializing a digital information recording medium capable of drop-out inspecting at a uniformized sensitivity over the whole area to be inspected of the recording medium after shortening an inspection time by using a format signal as a drop-out inspection signal. CONSTITUTION:In a format circuit 12, the recorded format signal is read out from the recording medium in which the format signal is recorded on a prescribed area through a magnetic head 24, and whether or not the format signal is written correctly is inspected. Together with that, in a drop-out inspection circuit 14, the read out format signal is compared with a prescribed threshold value set according to the period of the format signal, and the presence of the drop-out is inspected based on the compared result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for initializing a digital information recording medium for recording a format signal in a predetermined area.

[0002]

2. Description of the Related Art Conventionally, for a magnetic disk such as a floppy disk, a so-called format signal for defining an address of the magnetic disk is recorded in advance as digital information for the convenience of the user. This format signal is recorded in the format process of manufacturing a magnetic disk.

On the other hand, in a so-called certifying step, which precedes the above-mentioned formatting step, a magnetic disk is inspected for defects such as dropout (Japanese Patent Laid-Open No. 62-1 / 1987).
No. 73675), and as a result, only the good products are conveyed to the above-mentioned formatting process and the recording and inspection of the formats are performed (Japanese Patent Laid-Open No. 3-2831).
44).

The dropout inspection in the certifying step is generally performed as follows. That is, first, of the signals used for recording on the magnetic disk, the single cycle signal sequence of the shortest cycle is recorded as the inspection signal over the entire recording area of the magnetic disk. After that, the inspection signal is reproduced, and the slice level of the inspection is set using the average value of the amplitude of the reproduced signal as a reference value. Then, it is determined whether or not there is a dropout by comparing this slice level with the reproduction signal.

At the time of the dropout inspection in the certifying step, for example, for a 3.5-inch micro-floppy disk having a capacity of 2 MB, one rotation is performed for each track (1) inspection signal recording, (2) dropout inspection, and (3) seek. In the end, three rotations of the magnetic disk are required to inspect one track.

Furthermore, after a product which has passed the certifying process is conveyed to the formatting process and a format signal is recorded for each track, a comparison test with the original format signal is performed to check whether the recorded data has an error. And so on.

[0007]

As described above, in the conventional initialization method, many processes are performed for inspection in the certify process and the format process, and the total required time becomes extremely long. , It is requested to shorten this.

As a method for responding to such a demand, a certifying step and a formatting step are combined into one step, the above format signal is used as a dropout inspection inspection signal, and a format data comparison inspection is performed by a reproduced format signal. It is possible to reduce the inspection time by performing the dropout inspection as well as the inspection.

However, since the above format signal is generally modulated and recorded by a system such as FM or MFM, the reproduced format signal does not become a single cycle signal sequence, and a plurality of cycle signals having different cycles depending on the information content. It becomes a line. Therefore, the format signal basically has a different signal amplitude for each half wavelength. Therefore, in such a case, if the dropout inspection is performed at a single slice level as in the conventional case, it becomes impossible to perform the inspection with uniform sensitivity over the entire circumference of the track. That is, a signal with a short signal period has a small signal amplitude and thus has high dropout detection sensitivity, while a signal with a long signal period has a large signal amplitude and thus has low dropout detection sensitivity, and therefore an accurate dropout inspection is required. Will be difficult to do.

The above problem is not limited to the case of initializing the magnetic disk but may occur similarly in the case of initializing various digital information recording media.

The present invention has been made in view of the above circumstances, and uses the format signal as the dropout inspection signal to shorten the inspection time, and then the inspection area of the recording medium. It is an object of the present invention to provide a method for initializing a digital information recording medium that can perform a dropout inspection with uniform sensitivity over the entire area.

[0012]

A method for initializing a digital information recording medium according to the present invention does not set a slice level at the time of dropout inspection to a single level as in the conventional case, but a cycle of a format signal. It is intended to achieve the above-mentioned object by setting according to.

That is, the recorded format signal is read from the digital information recording medium in which the format signal is recorded in a predetermined area to detect whether or not the format signal has been correctly written.
The read format signal is compared with a predetermined threshold value set according to the cycle of the format signal, and a signal defect is detected based on the comparison result.

The "digital information recording medium" is not particularly limited as long as it is a recording medium capable of recording digital information, and is not limited to a magnetic recording medium such as a magnetic disk such as a floppy disk or a hard disk, but also an optical recording medium. It is a concept including other types of recording media such as information recording media.

The "cycle of the format signal" means the cycle of each signal component forming the format signal.

The "predetermined threshold value" is a threshold value (slice level) set so as to obtain a uniform dropout inspection sensitivity over the entire area to be inspected of the recording medium. This "predetermined threshold value" is specifically set to a large value for a long-cycle signal component whose signal amplitude increases and a small value for a short-cycle signal component whose signal amplitude decreases. To be done.

[0017]

As described above, the format signal read from the recording medium is compared with a predetermined threshold value set according to the cycle of the format signal, and based on the comparison result. Since the signal defect (dropout) is detected, not only the format signal can be used as the dropout inspection signal, but also the sensitivity of the dropout inspection is made uniform over the inspected area of the recording medium. It can be

Therefore, according to the present invention, the inspection time can be shortened by using the format signal as the dropout inspection signal.
The dropout inspection can be performed with uniform sensitivity over the entire inspection area of the recording medium, and the inspection accuracy can be improved.

[0019]

EXAMPLE An example of the method for initializing the digital information recording medium according to the present invention will be described below.

FIG. 1 is a block diagram showing an initialization device 10 used in this embodiment.

The initialization device 10 is provided with a format circuit 12 and a dropout inspection circuit 14 for recording a format signal on a floppy disk, reproducing / inspecting the format signal, and inspecting a dropout. It has become.

The format circuit 12 includes a format pattern generator 16, a signal recording circuit 18, a signal reproducing circuit 20, and a format pattern inspecting circuit 22.

The format pattern generator 16 includes
A format signal (format pattern) for one track of the floppy disk is generated as digital information, and this format signal is output to the signal recording circuit 18. Then, this signal recording circuit 18
Modulates the format signal by the FM or MFM method, outputs a current signal corresponding to the modulated format signal to the magnetic head 24, and the magnetic head 24
The above-mentioned format signal is written to a predetermined position of the floppy disk via a track for each round of the track.

On the other hand, a current signal (that is, a format signal as an analog signal) read from the floppy disk one track at a time via the magnetic head 24.
Is reproduced as a format signal converted into a digital signal in the signal reproduction circuit 20, and then input to the format pattern inspection circuit 22.
Then, the format pattern inspection circuit 22 carries out an identification inspection as to whether or not the input format signal is the same as the format pattern generated by the format pattern generator 16, for example, by comparing or bit by bit data. It is designed to measure the margin. The format pattern inspection circuit 22 can be composed of various inspection circuits conventionally used for format pattern inspection.

The format circuit 12 selectively outputs either the format signal from the signal recording circuit 18 to the magnetic head 24 or the input of the format signal from the magnetic head 24 to the signal reproducing circuit 20. A double changeover switch 26 is provided.

Next, the dropout inspection circuit 14, which is a characteristic part of the apparatus of this embodiment, will be described.

The dropout inspection circuit 14 is a circuit for detecting a dropout of a format signal read from the floppy disk via the magnetic head 24 during the format pattern inspection, and includes a period detection circuit 28 and a threshold selection. The circuit 30, the delay circuit 32, the half-wave rectification circuit 34, the envelope detection circuit 36, and the comparator 38 are provided.

A format signal read from the floppy disk via the magnetic head 24 and reproduced as a digital signal in the signal reproducing circuit 20 is input to the cycle detecting circuit 28. The digitized format signal is composed of a plurality of cycle signal sequences, and the cycle detection circuit 28 detects the cycle of each signal component included in the plurality of cycle signal sequences from the format signal. .

The threshold selection circuit 30 sequentially selects the thresholds of the dropout inspection set in accordance with each cycle detected by the cycle detection circuit 28, and the selected threshold is comparator 38. It is designed to output to.

The threshold value is set as follows. That is, the detection level for the same dropout defect is measured for all cycles by a preliminary test. Then, using the defect detection level in the shortest cycle (dropout detection standard value cycle) as a reference, the fluctuation rate in other cycles is calculated, and a predetermined threshold value in which this fluctuation rate is added is applied to all cycles. It is done by setting.

On the other hand, the format signal (analog signal) after being read from the floppy disk through the magnetic head 24 and before being input to the signal reproducing circuit 20, the delay circuit 32, the half-wave rectifying circuit 34 and the envelope detecting circuit 36. Is output to the comparator 38 via.

The delay circuit 32 makes a threshold from the format signal reproduction so that the output timing of the signal from the envelope detection circuit 36 to the comparator 38 coincides with the output timing of the signal from the threshold selection circuit 30 to the comparator 38. The signal output timing from the delay circuit 32 is delayed by the delay time due to the signal processing up to the value selection. The format signal output from the delay circuit 32 is half-wave rectified by the half-wave rectifier circuit 34, and then the envelope of the half-wave rectified format signal is detected by the envelope detection circuit 36. 38
It is designed to output to.

The comparator 38 compares the level of the envelope signal from the envelope detection circuit 36 with a threshold value which is sequentially selected by the threshold value selection circuit 30 in accordance with the cycle of the format signal, and a part of the envelope signal is compared. However, when the level becomes smaller than the above threshold value, it is determined that there is a dropout defect.

The envelope signal is a curve whose level changes depending on the portion of the format signal consisting of a plurality of periodic signal sequences. However, since the threshold level also sequentially changes according to the period of the format signal, the dropout test is performed. The sensitivity can be made uniform over the entire area of the floppy disk to be inspected.

As described above in detail, in the present embodiment, the format signal read from the floppy disk is compared with a predetermined threshold value set according to the cycle of the format signal, and the comparison result is obtained. Since the dropout detection is performed based on this, not only the format signal can be used as the dropout inspection signal, but also the sensitivity of the dropout inspection can be made uniform over the inspected area of the floppy disk. it can.

Therefore, according to the present embodiment, by using the format signal as the dropout inspection signal, the inspection time can be shortened, and the entire inspection area of the floppy disk is made uniform. Dropout inspection can be performed with the specified sensitivity,
The inspection accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an initialization device used in an embodiment of an initialization method of a digital information recording medium according to the present invention.

[Explanation of symbols]

 10 Initialization Device 12 Format Circuit 14 Dropout Inspection Circuit 16 Format Pattern Generator 18 Signal Recording Circuit 20 Signal Reproducing Circuit 22 Format Pattern Inspection Circuit 24 Magnetic Head 26 Double Changeover Switch 28 Cycle Detection Circuit 30 Threshold Selection Circuit 32 Delay Circuit 34 Half-wave rectification circuit 36 Envelope detection circuit 38 Comparator

Claims (1)

[Claims] 1. A digital information recording medium in which a format signal is recorded in a predetermined area, the recorded format signal is read to detect whether or not the format signal has been correctly written, and to read the format signal. A method for initializing a digital information recording medium, comprising: comparing the formed format signal with a predetermined threshold value set according to the cycle of the format signal, and detecting a signal defect based on the comparison result.