JPH0583962B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to the use of extra and
The present invention relates to an apparatus for inspecting the presence or absence of errors, and in particular to an apparatus capable of accurately inspecting the entire length of a track.

[Conventional technology]

When a disk-type magnetic recording medium whose recorded contents have been completely erased is read, a signal indicating some information is read from the disk. This phenomenon is called data leakage. The defects that occur are called extra errors. Conventionally, when inspecting for the presence or absence of extra errors at the stage of quality inspection of disk-type magnetic recording media, the entire section of the disk or track to be inspected is set as the write section, and the magnetic head is After energizing the track sharply to perform writing (that is, DC erasing) for the section, the DC current is abruptly cut off (see Figure 5 b and c), and then the track is read to eliminate the extra error. An inspection process was performed to check for the presence or absence of . Incidentally, FIG. 5a shows an index signal that serves as a reference when performing the above writing.

[Problem that the invention seeks to solve]

However, in this inspection method, the location on the track that was passing in the immediate vicinity of the head when the head was suddenly excited or when the DC current was abruptly cut off (i.e., the location on the track that is the start or end of erasing) is 5), the signal with the waveform shown in Figure 5d, which was written based on the current flowing to the head during the transient response, is read out during readout, making it impossible to determine the presence or absence of data leakage. It was gone. Therefore, there was a problem in that it was not possible to inspect the entire track for the presence of extra errors, and the quality of the disk to be inspected could not be fully guaranteed.

This invention was made in view of the above points,
It is an object of the present invention to provide a disk type recording medium inspection device that can accurately inspect the presence or absence of abnormalities such as extra errors over the entire track section.

[Means and actions for solving problems]

The disk-type recording medium inspection device according to the present invention writes a DC signal at a predetermined level over the entire section of a given track of a disk-type recording medium to be inspected, erases the recorded contents of the track, and then subsequently writes an erasing control means for writing in a part of the track while attenuating the signal level with a predetermined time constant and repeatedly erasing the recorded contents of the part, and reading out the track after the erasing operation is completed. The present invention is characterized by comprising: a test processing means for performing a test process for checking the presence or absence of an abnormality regarding the track based on the read signal.

When a DC signal of a predetermined level is written over the entire section of a certain track of the disk to be inspected under the control of the erasure control means, the recorded contents of the track up to that point are erased accordingly. . Next, in the track, starting from the point where the writing of the DC signal at the predetermined level is the end, the DC signal is written in a part of the section while the level is attenuated at a predetermined time constant under the control of the erase control means. will be written to. As a result, erasure of recorded contents is performed redundantly in this part of the section on the track. When all of the above write (erase) operations are completed, the track is then read out and the read signal is given to the inspection processing means. The inspection processing means performs an inspection process to determine the presence or absence of an abnormality regarding the track of the disk to be inspected based on this read signal.

Here, a waveform as shown in FIG. 5d is written at the point on the track where the write (erase) operation starts due to the transient response of the head, but this waveform overlaps at that point. It is erased when a DC signal is written. Furthermore, before the write (erase) operation is completed, the DC signal does not abruptly cut off, but its level attenuates with a predetermined time constant. A waveform such as that shown in FIG. 5d, which is caused by the transient response of the head, is not written at that location. Therefore, the read signal given to the test processing means after the end of the write (erase) operation does not contain any waveform like the one shown in FIG. Based on this read signal, it is possible to accurately inspect the entire track section of the disk to be inspected for abnormalities such as extra errors.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing an embodiment of a disk-type recording medium inspection apparatus according to the present invention. This disk type recording medium inspection device 1 is provided with a time control section 2 and a mode control section 3.
An index signal for the magnetic disk 11 to be inspected is given from a drive device 12 equipped with the magnetic disk 11 to be inspected.

The time control section 2 outputs a signal "1" as a DC current control signal for a period of time starting from the time when a certain index signal is given until the next index signal is given (that is, while the disk 11 rotates one rotation). The signal "1" is applied to the output line L1 as a write control signal for a period longer than the above-mentioned time by the time required for a discharge phenomenon of the capacitor 14, which will be described later, starting from the above-mentioned time.
This occurs in 2. The output line L1 of the time control section 2 is connected to the input of the gate circuit 4, and the output line L2 is connected to the input of the gate circuit 5. The mode control section 3 performs mode control of several inspection items based on the index signal. The mode control section 3 supplies the control inputs of output gate circuits 4 and 5 that generate a signal "1" when the "erase" mode is selected.

According to this invention, the inspection device 1 includes an analog
A gate circuit 7 and a capacitor 14 are provided. A DC current of a predetermined level is applied to the input of the analog gate circuit 7 from a DC current generator. The output signal of the aforementioned gate circuit 4 (that is, the DC current control signal of the time control section 2) is applied to the control input of this analog gate circuit 7, and the output current of the analog gate circuit 7 is applied to the capacitor 14. Capacitor 14 is connected when analog gate circuit 7 is opened (i.e. gate circuit 4
When the signal "1" is given as a DC current control signal from the time control unit 2 via That is, when the signal "1" is no longer applied as the DC current control signal), discharging is performed at a predetermined time constant.

The output of capacitor 14 is given to the input of write control gate circuit 8. Output of the aforementioned gate circuit 5 (i.e., write control signal of time control section 2)
is applied to the control input of the write control gate circuit 8, and the output current of the write control gate circuit 8 is applied to the read/write head 13 of the drive device 12 via the read/write separation section 9.

The inspection processing section 10 performs inspection processing for the presence or absence of extra errors on the disk based on the readout signal of the disk to be inspected, and outputs a signal indicating the inspection processing result. A signal read from the disk 11 by the head 13 is applied to the test processing 10 via the read/write separation unit 9.

Next, an example of testing for the presence or absence of extra errors on a hard magnetic disk using this testing device 1 will be described with reference to FIGS. 2 to 4. The index signal of the disk 11 that is rotationally driven on the drive device 12 begins to be given to the time control section 2 and the mode control section 3, and the time control section 2 starts to receive a certain index signal as shown in FIGS. 2a to 2c. Output lines L1, L2 starting from time t1
DC current control signal “1”, write control signal “1”
, respectively, and at this time, the mode control unit 3 selects the "erase" mode and sends the signal "1" to the gate circuit 4.
At this time, the DC current control signal “1” is applied to the control input of the analog gate circuit 7 via the gate circuit 4 to open the gate circuit 7, and the write control signal “1” is applied to the control input of the analog gate circuit 7. ” is applied to the control input of the write control gate circuit 8 via the gate circuit 5 to open the gate circuit 8.

At this time, the analog gate circuit 7 outputs a constant DC current based on the DC current supplied from the DC current generator 6, as shown in FIG. 2d. This DC current instantaneously charges the capacitor 14 and is applied to the head 13 as a write current via the write control gate circuit 8 and the read/write separation section 9, thereby exciting the head 13.
The head 13 writes this DC current into a certain track of the disk 11 to erase the recorded contents of that track.

As shown in FIG. 2a, when the next index signal is applied from the drive device 11 at time t2 (therefore, when the disk 11 is rotated one rotation and erasing is performed over the entire section of the track),
As shown in FIG. 2b, the time control section 2 no longer outputs the DC current control signal "1". At this time, the analog gate circuit 7 is closed, and a direct current that decays with a predetermined time constant begins to be discharged from the capacitor 14, as shown in FIG. 2d. This current is also applied to the head 13 as a write current via the gate circuit 8 and the read/write separation section 9. The head 13 continues writing (erasing) on the track using this direct current. Time t3 when the current discharged from the capacitor 14 becomes zero
When this time arrives, the time control section 2 no longer outputs the write control signal "1" as shown in FIG. 2c. At this time, the write control gate circuit 8 is closed, and all write (erase) operations for the track are completed. In other words, the above writing (erase)
As a result of the operation, as shown in FIG. 3, the recorded contents are erased over the entire section of the track and overlapping the section from the erase start point A to the end point B.

The erased track is then read out by the head 13, and the head 13 supplies a read signal covering the entire section of the track to the test processing section 10 via the read/write separation section 9. The inspection processing unit 10 performs inspection processing for the presence or absence of extra errors on the track on the disk 11 based on this read signal,
Outputs a signal indicating the inspection processing result.

Here, at time t1, which is the start of erasing, head 1
Due to the transient response of 3, a waveform as shown in FIG. It is erased at the time of the second erase (ie, time t2). Furthermore, before the erasure is completed, the DC current gradually decreases from time t2 to t3.
A waveform such as is not written at the location on the track where erasing ends (position B in FIG. 3). Therefore, the track readout signal given to the inspection processing section 10 after completing this erasing does not include the waveform shown in FIG. 5d, which is caused by the transient response of the head 13, as shown in FIG. Not yet. Thereby, the inspection processing section 10 can accurately perform inspection processing for the presence or absence of extra errors over the entire section of the track on the disk 11 based on this read signal.

In this manner, the inspection apparatus 1 can accurately inspect the entire track section of a hard magnetic disk for the presence or absence of extra errors without being affected by the transient response of the head.

In this embodiment, the extra
Although the present embodiment checks for the presence of errors, it may also be possible to check for the presence or absence of extra errors in other disk-type recording media such as flexible disk cartridges.

〔Effect of the invention〕

As described above, according to the disk-type recording medium inspection apparatus according to the present invention, it is possible to accurately inspect the entire track section of the disk-type recording medium to be inspected for abnormalities. Therefore, it becomes possible to improve the level of inspection and guarantee the quality of the disk-type recording medium more reliably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a disk-type recording medium inspection device according to the present invention, and FIG. 2 is a diagram showing an example of the temporal relationship of output signals of each part in the same embodiment. Figures illustrating the index signal output from the device, b and c depicting the DC current control signal and write current control signal output from the time control section, respectively, and d depicting the DC current output from the analog gate circuit. Figure 3 is a diagram showing an example of a hard magnetic disk read signal given to the inspection processing section in the same embodiment;
The figure shows an example of the section on the track of the magnetic disk where DC current is written in the same embodiment, and Figure 5 shows an example of the input/output signals of each part when using the conventional inspection method. In the figure, a shows an index signal, b shows a write gate signal, c shows a write current applied to the magnetic head, and d shows a read signal of the disk under test. DESCRIPTION OF SYMBOLS 1... Disk type recording medium inspection device, 2... Time control section, 3... Mode control section, 4, 5... Gate circuit, 6... Direct current generator, 7... Analog gate circuit, 8... ...Write control gate circuit,
9...read/write separation section, 10...inspection processing section, 11...magnetic disk, 12...drive device, 13...read/write head, 14...
capacitor.

Claims (1)

[Claims] 1. Writing a DC signal at a predetermined level over the entire section of an arbitrary track of a disk-type recording medium to be inspected, erasing the recorded contents of the track, and subsequently changing the level of the DC signal to a predetermined level. erasing control means for writing in a part of the track while attenuating with a time constant and erasing the recorded contents of the said section repeatedly; reading the track after the erasure control means finishes the erasing operation; A disk-type recording medium inspection device comprising: inspection processing means for inspecting the presence or absence of an abnormality regarding the track based on the read signal. 2. The erase control means includes a current generation means for generating a predetermined DC current, an analog gate circuit for inputting the DC current given from the current generation means, and a current generating means for inputting the DC current given from the current generation means, and a A capacitor that is instantly charged and discharged at a predetermined time constant when the analog gate circuit is closed; and a control that opens the analog gate circuit during at least one revolution of the disk-type recording medium to be inspected. 2. A disk-type recording medium inspection device according to claim 1, comprising: means.