JP2531293B2 - Defect inspection device for disc-shaped information recording medium - Google Patents

Description

The present invention relates to a defect inspection apparatus for disc-shaped information recording media such as optical discs, magnetic discs, and magneto-optical discs.

[Problems to be Solved by Prior Art and Invention]

In a disc-shaped information recording medium such as an optical disc, a signal is recorded on a spiral or concentric track.
Therefore, unlike a magnetic tape in which signals are linearly recorded, a wide range of defects over a plurality of adjacent tracks,
That is, burst defects may occur.

FIG. 23 shows the disc-shaped information recording medium and the state of its burst defects. In this example, the disk-shaped information recording medium 51 has spirally formed tracks, and there are defects 52a over 5 tracks and defects 52b over 2 tracks. When a reproduction signal is obtained from such a disc-shaped information recording medium, seven dropout pulses P1 to P7 are detected as shown in FIG.

Only by detecting the dropout pulse, the number of individual defects on the track of the disc-shaped information recording medium can be detected, and whether or not there is a so-called burst defect in a lump, and the number and position thereof are determined. It cannot be detected. For this reason, in the past, an operator often used visual inspection using a microscope, for example, to detect a burst defect.

For the purpose of detecting such a burst defect, for example, the invention of Japanese Patent Publication No. 63-27779 has been proposed. The invention of Japanese Examined Patent Publication No. 63-27779 has a circuit diagram as shown in FIG. 25, and the signal states of the respective parts are as shown in the timing chart of FIG.

In the figure, 53 is an input terminal for a reproduction signal from the disc-shaped information recording medium, and the dropout pulse as shown in FIG. 10 is included as the dropout pulse a as shown in FIG. 26 (A). There is. This dropout pulse a is input to the flip-flop 54.

The flip-flop 54 enters the set state as shown in FIG. 26 (B) when the dropout pulse a is input from the input terminal 53, and its output signal b becomes high level.

The counter 55 counts the clock CL input from the terminal 56 when the flip-flop 54 is in the set state and the high-level output signal b is input, and the result is a predetermined number, specifically, a drop. When the number corresponding to a time slightly shorter than the time from the first pulse generation of the out pulse a to the one rotation of the disk is reached, the counting end signal is output. When this counting end signal is given, the monostable multivibrator 57 is triggered and outputs a rotational position pulse d having a predetermined width as shown in FIG. 26 (D). The rotational position pulse d is given to the flip-flop 58 and the monostable multivibrator 59.

When the rotational position pulse d is applied, the monostable multivibrator 59 outputs a pulse c as shown in FIG. 26 (C), which is applied to the reset terminal of the flip-flop 54. As a result, the flip-flop 54 is reset as shown in FIG. 26 (B), and the counting of the counter 55 is stopped. The pulse c output from the monostable multivibrator 59 is also given to the counter 60.

When the next dropout pulse a'is input to the input terminal 53 again during the period when the rotational position pulse d output from the monostable multivibrator 57 is at high level, the flip-flop 54 is set again and the counter 55 counts. The flip-flop 58 is set in synchronization with the falling edge of the output pulse d of the monostable multivibrator 57.
A signal e as shown in FIG. 26 (E) is output. The state of the flip-flop 58 is determined by the signal d and the signal b. If the signal b is at the high level when the signal d falls, the flip-flop 58 is in the set state, and if the signal b is at the low level, the flip-flop 58 is reset. Be put in a state.

When the dropout disappears after the disk has rotated three times from the first dropout, the flip-flop 54 continues to be reset by the output pulse c of the monostable multivibrator 59, and the flip-flop 58 causes the falling edge of the signal d and the signal b. It is reset by the low level of. When the flip-flop 58 falls, the monostable multivibrator 61 outputs a dropout end signal f as shown in FIG. 26 (F).

As described above, the output pulse c of the monostable multivibrator 59 is input to the counter 60. The counter 60 counts the number of output pulses c, that is, the number of continuous tracks having dropouts. The count value of the counter 60 is given to the gate circuit 66. The output signal of the monostable multivibrator 61 is given to the gate circuit 66 as a trigger signal. With such a configuration, when the dropout end signal f is output, the number of continuous tracks having dropouts is output from the gate circuit 66.

In this embodiment, the gate circuit 66 outputs the number of continuous tracks, not the number itself. The gate circuit 66 classifies the number into three levels and outputs a signal from the terminal 66a, 66b or 66c corresponding to the three levels. Dropout end signal f
Is supplied as a reset signal to the counter 60 via the delay circuit 68.

As described above, in the invention of Japanese Examined Patent Publication No. 63-27779, the rotational position pulse d is generated due to the occurrence of the dropout, and if the dropout pulse a exists correspondingly, a series of defects are formed in a lump in the radial direction of the disk. The presence of aggregated so-called burst defects is detected.

However, in the invention of Japanese Patent Publication No. 63-27779 mentioned above, when a plurality of defects are present on the same track at a certain interval, in the circuit having the above configuration, one defect on the same track is present. Since it is only possible to detect, it is necessary to prepare a plurality of sets of circuits, or to perform a plurality of inspections by slightly shifting the timing of dropout detection. Further, the size of the burst, that is, the length of the disc-shaped information recording medium in the circumferential direction cannot be detected.

Japanese Unexamined Patent Publication No. 64-72087 proposes a method for determining and inspecting the position of dropout on a magnetic disk. This method determines the dropout angle (circumferential position) and radial position, stores these positions, and controls the position of the magnetic disk facing the inspection device such as a microscope based on the stored position information. To do. However, in such a method, even if there is a burst defect, the position of the magnetic disk is controlled for each unit dropout (for one bit of data),
The inspection efficiency is poor.

Further, the defect includes a physical defect and a data defect, and since these types are related to the process after the defect detection, their identification,
Although memory is required, the two publications mentioned above do not disclose any technology to meet such demands.

The following optical disc recording format is ISO standard 5.25.
The inch type will be explained.

Tracks are formed on the disc-shaped information recording medium 51 in a spiral shape or a concentric shape. As shown in Fig. 27, PEP (Phase Encode Par
t) Control track 51A, SEP (Standard Format Pa
rt) It is divided into a control track 51B, a user area 51C, and a SEP control track 51D. Data such as recording / reproducing conditions of the disc-shaped information recording medium 51 is recorded in each control track, and the user area
51C is used by the user to record arbitrary data.

In the disc-shaped information recording medium 51, each track other than the PEP control track 51A is radially divided to form a sector. Each sector is composed of a header section 50A in which track and sector addresses are recorded and a data section 50B for recording data.
However, the data part 50B of the SEP control tracks 51B and 51D
As described above, various data of the disc-shaped information recording medium 51 is recorded, and the data section 50B of the user area 51C is a section for the user to record data, and is unrecorded at the inspection stage in the factory. Is. A flag section 50C is formed on the top side of the data section 50B of the user area 51C.

In the disc-shaped information recording medium 51 having such a format, the type of defect and the inspection method are different in each part. For example, since the data portion 50B of the user area 51C is unrecorded, there can be no data defect here, only a physical defect. On the other hand, both types of defects may occur in the header portion 50A of the user area 51C, and in the case of a data defect, since the inspection content is different, it is necessary to identify the type of the defect. So, in the past, SFP
In the user area, since the header section 50A and the data section 50B are alternately present over the entire circumference, the inspection of only the header section 50A over the entire track and the inspection of only the data section 50B are combined twice. I was going to do it. Therefore, there is a problem that the inspection efficiency is low.

The present invention has been made in order to solve such a problem, and treats individually detected 1-bit defects as a defect block collectively based on the position information thereof, and further Disc-shaped information that can be easily handled in subsequent microscopic inspections, etc., by detecting the type and storing information on the type, position, and size of the defect, defective lump, and performing reproduction once for the defect detection. An object of the present invention is to provide a defect inspection device for a recording medium.

[Means for solving the problem]

In order to achieve such an object, in the defect inspection apparatus of the present invention, a means for detecting a defect by a reproduction signal from a disc-shaped information recording medium, a means for detecting the type of the detected defect, and a detected A means for detecting the radial position and the circumferential position of the defect, a means for dividing the defect into defect lumps based on the detected position, a means for calculating the radial dimension and the circumferential dimension of the defect lump, and the detected Type of defect or defective mass,
And means for storing the position and dimensions.

[Action]

The information recording medium to be inspected is applied to a reproducing device to obtain a reproduced signal. The defect is detected by the reproduction signal, and the type, the radial position and the circumferential position are also detected. Next, based on these detected positions, the defects that are approaching are grouped as a defect block, and the radial and circumferential dimensions thereof are calculated. Then, the types, positions, and dimensions of these defects and defective blocks are stored. An inspection using a microscope is performed using this stored content.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment of an optical disc.

FIG. 1 is a block diagram showing the overall configuration of the device 1 of the present invention (enclosed by a broken line). An optical disk (not shown) to be inspected is loaded into a reproducing apparatus (optical disk drive) 2, and an analog reproduced signal obtained by this is sent to a defect dimension information detecting section 3 and an A / D (analog / digital) converter 4. Is entered. The defect size information detection unit 3 detects the size of the defect and supplies it to the defect type detection unit 7. The A / D converter 4 converts the input analog reproduction signal into a digital signal, and the reproduction data is input to the control track error detection section 5 and the address decoding / gate signal generation / header error detection section 6. The control track error detection section 5 detects an error included in the control data recorded in the data section 50B of the SFP control tracks 51B and 51D, and gives the result to the defect type detection section 7.

The address decoding / gate signal generation / header error detection unit 6 uses the SFP control tracks 51B and 51D and the user area 51C included in the reproduced data as header units 50, respectively.
The address signal reproduced from A is decoded to identify the area on the track, and the result is output to the track position information detection unit 9 and the angle / sector position information detection unit 10, and is also recorded in each information recording area being reproduced. In response, a gate signal is generated and output to the defect type detection unit 7. It is also output to the angular sector position information detection unit 10. The address decode / gate signal generation / header error detection unit 6 also detects an error (header error) included in the data recorded in each header unit 50A, and supplies the result to the defect type detection unit 7.

The defect type detection unit 7 detects the defect detection result provided from the defect size detection unit 3, the control track error detection unit 5, and the address decode / gate signal generation / header error detection unit 6 and the information on the defect type from the gate signal. Then, the result is stored in the memory 11.

The reproducing apparatus 2 outputs one rotation pulse for each rotation of the optical disk, and this pulse is input to the angle / sector position information detecting unit 10 and the track position information detecting unit 9. The track position information detection unit 9 detects information about a track having a defect or an error from the rotation pulse and the address decoding result supplied from the address decoding / gate signal generation / header error detection unit 6, and stores it in the memory 11.

The angle / sector position information detecting unit 10 detects a defect or an error from the reference position on the disc-shaped information recording medium based on the result of the rotation pulse and the address decoding, the gate signal generation, and the address decoding provided by the header error detecting unit 6. Information about angles and sectors is detected and stored in memory 11.

The memory 11 stores the detection results of the defect type detection unit 7, the track position information detection unit 9 and the angle / sector position information detection unit 10 described above.

The computer 8 reads the defect and error data stored in the memory 11 and detects a defect block described later, and further outputs position information of the XY stage for inspecting an optical disc to be detected by a microscope.

Defect size detection unit 3, A / D converter 4, control track error detection unit 5, address decode / gate signal generation / header error detection unit 6, defect type detection unit 7, track position information detection unit 9, angle / Sector position information detector 10, memory 1
The defect detection apparatus 1 of the present invention is configured by 1 and the computer 8.

Each part will be described in detail below. First, the defect dimension information detection unit 3 will be described.

FIG. 2 is an enlarged schematic view of burst defects existing on the disc-shaped information recording medium.

In the figure, the lower side of the disk 20 is the center of rotation and the upper side is the outer edge portion. A large number of tracks T are formed on the disk 20, and the eleventh tracks T11 to T21 are shown as an example in FIG.
Track T21 is shown.

21 is a burst defect.
It runs from 13th track T13 to 20th track T20.
Therefore, the number of cross tracks is 8, and the track center is the 17th track T17.

Now, assuming that the 20th track T20 is being reproduced by the reproducing device 2, for example, the circumferential length information of the defective portion hatched in the drawing is obtained from the defect dimension information detecting unit 3. The defect dimension information detection unit 3 is included in the reproduction signal,
A dropout pulse generation circuit 3a that obtains a dropout pulse by detecting a signal caused by a defect, and a counter that counts the length of each dropout pulse as the number of clocks.
With 3b.

The counter 3b uses the circumferential length of the counted defect as an 11-bit binary number and the selector 7a of the defect type detection unit 7 (FIG. 3).
Output to bits 0, 1, 2 to A, B of.

FIG. 4 shows the data format (a), gate signal, and error signal (b) for one sector of the user area 51C.
(H) is illustrated. The address decoding / gate generation / header error detection unit 6 gate generation unit (FIG. 8) issues various gate signals based on this format (a).

FIG. 4B shows the gate signals of the SFP control tracks 51B and 51D, which are "L" when the user area 51C is reproduced. This gate signal is given to the selectors 7a, 7b, 7c of the defect type detecting section 7 shown in FIG. Fig. 4 (c)
The header gate shown in (1) becomes "H" during reproduction of the header area, and this is output to the bit F of the defect type detection unit 7. The flag gate shown in FIG. 4 (d) becomes "L" level only in the flag area (ODF, UFO3) at the beginning of the data area. This gate signal is given to the defect type detection unit 7 as a bit E. FIGS. 4 (e) and 4 (f) show the presence / absence of a data error in the SFP control track and a SYNC / RESYNC error in the data area of the SFP control track. If there is no such error as shown in the figure, it remains "L". Is. These signals are output from the SFP control track area data detector 5. Both error signals are output to the bits D and C of the defect type detector 7.

When there is a defect in the data area of the user area 51C, the timing is as shown in FIG. 4 (g), and when there is a defect signal in the flag area, it is shown in FIG. 4 (h). As shown, a pulse also appears at that timing. As described above, these pieces of dimensional information are input to bits 0 to B of the defect type detection unit as an 11-bit binary number.

FIG. 5 shows the error occurrence status of the header part. When a signal indicating a CRC (Cyclic Reduducy Check) error is obtained in the header area, CRC1, CRC2, CRC3 or a pulse indicating an SM error is obtained and output to bits 3, 2, 1, 0 of the defect type detector 7, respectively. To be done. The error in the header area is performed by the header error detection unit of the address decoding / gate signal generation / header error detection unit 6.

FIG. 6 is a timing chart when there is a data error in the SFP control track. The control gate signal is at high level as shown in FIG. 6 (b). Control track error detector 5 is SFP
If there is an error in the control track 51B or 51D, it is detected and a signal as shown in FIGS. 6 (e) and 6 (g) is output, and this is output to the bit D and the bits 0 to B of the defect type detection section 7. Output.

Fig. 7 shows SYNC and RESY of the same SFP control track.
The time chart when there is an error in NC is shown. In this case, the same as in the case of FIG. 6 except that a high level signal appears in the SYNC and / or RESYNC area.

FIG. 8 is a block diagram showing the configuration of the address decode / gate signal generator / header error detector 6. A / D
The reproduced data digitized by the converter 4 is given to the sector mark (SM) detection section 6a and the address mark (AM) detection section 6b of the gate generation section, and the sector mark detection section 6a is provided in the user area 51C and the SFP control area. The sector mark in the header area of 51B, 51D is detected, and if it is not obtained or there is an abnormality, an SM error signal is issued. This is output to bit 0 of the selector 7b as shown in FIGS. When the SM detection unit 6a detects the sector mark SM, the sector counter 6c is reset by this and the clock counting (not shown) is started. The count value is input to the gate generator 6d, and the gate generator 6d outputs a header gate signal and a flag gate signal according to the count value. The output gate signal is given to the selector 6e.

On the other hand, the address mark output from the address mark detection unit 6b is input to the address demodulation unit 6f, where address data is obtained and given to the track position detection unit 9 and the angle / sector position information detection unit 10. The address is checked by the CRC check unit 6h. If there is an error as a result of the check, a CRC error signal (CRC1,2,3) is output and given to the defect type detection unit 7. The gate generator 6g checks from the address whether it is the control area 51B, 51D or the user area 51C, and outputs a control track gate signal which becomes "H" in the former case, and this is the defect type via the selector 6e. It is input to the detection unit 7. The selector 6e is provided with a signal indicating whether or not the optical disc to be detected is formatted (non-formatted), thereby selectively outputting the header gate signal, the flag gate signal, and the control track gate signal.

The defect type detection unit 7 outputs 16-bit defect size / type data based on inputs from the defect size detection unit 3, the control track error detection unit 5, and the address decode / gate generation / header error detection unit 6. This 16-bit data is stored in the memory 11 together with the 16-bit data represented by the angle / sector from the angle / sector position information detecting unit 10 and the 16-bit data representing the track from the track position information detecting unit 9.

FIG. 9 shows an example of this stored data. FIG. 9A shows an example of a defect in the user area 51C or a defect in an unformatted disc. As described above, the LSB side is 0, 1, 2 ...
The defect size data is entered in 12 bits of A and B, and all 4 bits C, D, E, and F on the MSB side are 0.

FIG. 9B shows the data when the flag area of the format disc is defective, and the 4-bit data on the MSB side is "0100". That is, the flag gate is "H" for this defect.

FIG. 9 (c) shows the case where a header error exists,
The MSB side 4 bits are "1000", and the LSB side 4 bits are 0, 1, 2, and 3 according to SM error, CRC1, 2, and 3 errors, respectively.
Becomes The middle 8 bits are meaningless for this error, and are sectors rather than the second 16-bit angle.

FIG. 9D shows a data error in the control track, and in this case, the MSB side 4 bits are "0010". In addition, Fig. 9 (e) shows SYNC and RESYNC errors. The MSB side 4 bits become "0001" and the difference between SYNC error and RESYNC error is L.
It is identified by 2 bits on the SB side. Also in these cases, the data of the other part of the first 16 bits is meaningless.

FIG. 10 shows the codes of the above MSB side 4 bits and LSB side bits.

Next, data processing by the computer 8 will be described. 11 and 12 are flowcharts showing a processing procedure for defect type determination when the defect size / type data stored in the memory 11 is read as described above.

First, the computer 8 reads the defect data and sequentially examines the dimension data portion from the MSB side as shown in FIG. If the Fth bit is "1", the process proceeds to the header error subroutine (Fig. 12), and if the Fth bit is "0", the Eth process is executed.
If the bit is "1", it is determined that there is a flag area defect, if the Eth bit is "0" and the Dth bit is "1", it is determined that there is a control track data error, and the Dth bit is " If the 0th bit and the 0th C bit are "0", it is determined that the user area defect or the unformatted disc defect,
If the Cth bit is "1" and the 0th bit is "1", it is determined that a SYNC error has occurred. If the 0th bit is "0" and the 1st bit is "1", it is determined that a RESYNC error has occurred. To do.

In the header error subroutine, if the 0th bit is "1", it is judged as an SM error, and if the 0th bit is "0" and the 1st bit is "1", it is judged as a CRC1 error. If the first bit is "0" and the second bit is "1", it is determined that a CRC2 error has occurred, the second bit is "0" and the third bit is "1".
If so, it is determined to be a CRC3 error.

The computer 8 determines the type of defect from the defect data as described above.

Next, a procedure for classifying defective data into defective blocks will be described. FIG. 13 is a flowchart of the main routine, and FIGS. 14 to 17 are flowcharts of the subroutine.

The memory 11 stores the defect size / type data as described above. FIG. 18 shows an example of this stored information, and its size (SIZE), track number (TRACK) and angle (ANG
LE) is shown. No. is the alignment number, CLASS is expressed in S, M, L in three steps according to the size (here, all are M), and R is the distance from the center of the track.
The computer 8 reads such data, sorts the defect data in the descending order of the tracks (in order from the largest value to the smallest value), and then initializes the parameter I to "1" (steps S1 and S2). I is the number of sorted defect data. FIG. 19 is a list of data after sorting.

Letting [I] be the number of the track where the I-th defective data exists, if [I + I]-[I] is "0", it means that there is another defective data on the same track.
"-1" means that defective data exists in the adjacent track. If it is "-2" or less, it means that the defect data exists on the discontinuous track, that is, that at least one track is separated and two defects exist. Therefore, in step S3, [I + 1]-[I] is calculated and the defects are classified (steps S3, S4, S5, S6).

In the computer 8, the result of step S3 is "0" or "-1".
In case of, both of them are counted (steps S7, S8),
In the case of "-2" or less, since continuous defects have been detected in steps S5 and S8 by that time, the track number of the center thereof is stored (step 9).

In FIG. 19, when I = 1, [I-1]-[I] is 17133-18411≤-2, and the defect of the track of [I] = 18411 is regarded as the defect on the discontinuous track.

When I = 2, 17132−17133 = −1, so it is regarded as a defect on a continuous track. This state continues until I = 20.

At I = 21, 11954−17114 ≦ −2, so the 22nd defect is regarded as a defect of a track which is discontinuous with the previous one. Then, the 2nd to 21st defects are recognized as one defect block. In step S9, the centers of the 2nd to 21st tracks are obtained and stored as 11 or 12.

Similarly, the defects on the 22nd and 23rd tracks are also recognized as defective blocks.

In this example, there is no defect corresponding to [I + 1]-[I] = 0.

The computer 8 performs the above processing for all the defect data while incrementing the parameter I by "1" (steps S10 and S11).

Next, the computer 8 initializes the parameter J to "1" (step S12), and checks whether the track [J] (Jth track) is the center of the continuous defect or not in the above step S9.
Judgment according to the data stored in (step S1
3). If "YES", the process of the burst defect subroutine (step S15) shown in FIG. 14 is executed, and if "NO", the process directly proceeds to step S15.

The burst defect subroutine will be described later in detail in the 14th
The process is as shown in the flowchart of the figure, and the upper and lower limits of the continuous defective track indicating the range where the tracks having the defective data are continuous, the central track, and the continuous number are detected. The computer 8 executes this process with the parameter J
While incrementing by 1 (step S1
6) If completed, the defect separation subroutine is executed (step S17).

This defect separation subroutine is a process for separating defects on the same track based on the circumferential angle of the disc-shaped information recording medium, which will be described later in detail with reference to the flowchart shown in FIG. In other words, when a plurality of defects are present on the same track, it is detected whether one burst defect is formed or is a separated defect depending on the angle from the reference position of the disc-shaped information recording medium.

When the processing of the defect separation subroutine of step S17 is completed, the computer 8 outputs the result to, for example, a CRT display or a printer (step S18).

FIG. 14 is a detailed flowchart of the burst defect subroutine.

First, the computer 8 initializes the parameter M to J (step S20), and increments the parameter M by "1" until "M + 1"-[M] becomes smaller than "-2" (step S22). , [M + 1]-[M] is "-2"
If it becomes smaller (step S21), the track number [M]
Is set as the lower limit of continuous defective tracks, that is, the innermost track (step S23).

In this process, the track numbers are sequentially checked from the center of the continuous defect, that is, the defect block, and if the track numbers are separated by 2 or more, it is determined that they are the ends of the defect block. For example, if M = J = 12 in the defect masses of Nos. 2 to 21, M is incremented in order from [13]-[12] = 17122-17123 and [22]-[21] = 11954-17114≤-2. When this happens, M = 21 is set as the innermost track of this defective block.

Similarly, the computer 8 initializes the parameter L to J (step S24) and increments the parameter L by "1" until [L-1]-[L] becomes larger than "2" (step S24). S26), if [L-1]-[L] becomes larger than "2" (step S25), the track of the track number [L] is set as the upper limit of continuous defective tracks, that is, the track at the outer limit of the defect block (step S25). Step S27).

Finally, the computer 8 stores the upper and lower limits of the continuous defective track and the center track, and calculates and stores the number of continuous tracks using the upper and lower limit values (step S2).
8).

In the example of FIG. 19, when L = 12 is calculated and L = 2, [1]-[2] = 18411-17133 ≧ 2 and L =
The second track is the outermost track.

FIG. 15 is a flowchart of the defect separation subroutine.

First, the computer 8 initializes the parameter K to "1" (step S31), stores the data of each track of the first burst defect (defect block) (step S32), and executes the processing of the angle subroutine (step S33). ).

The angle subroutine will be described in detail as shown in the flow chart of FIG. 16. In short, whether a plurality of defects on the same track constitute one burst defect,
Alternatively, it is a routine for determining whether the defects are separated from each other.

By the processing of the angle subroutine in step S33, it is determined whether the plurality of defects on the same track are a group of burst defects or different burst defects. Therefore, the computer 8 increments the parameter K by "1". After performing the above-described processing for each burst defect (step S35), the process returns.

 FIG. 16 is a flowchart of the angle subroutine.

First, the computer 8 sorts the same defect blocks, that is, the Kth burst defect angle (ANGLE) in descending order (step S40). Figure 20 shows the results sorted in descending order of angle.

Next, the parameter N is initialized to "1" (step S4
1), the angle [N] of the defect number N in the burst defect that is the processing target in step S32 of the defect separation subroutine
With respect to [N]-[N-1] ≤0.3 °, the number of defects is counted as continuous defects in the circumferential direction of the disc-shaped information recording medium (steps S42, S43), and [M]- [M
If +1] is larger than 0.3 °, it is determined that the defect of number N and the defect of N + 1 are different, and the processing of the burst data subroutine (step S44) is executed. It should be noted that in the example of FIG. 20, two defect masses do not exist in the circumferential direction.

The computer 8 executes the above process while incrementing the parameter N by "1" until the parameter N reaches the number of burst defects (steps S45, S46), and returns when the parameter N reaches the number of burst defects.

FIG. 17 is a flowchart of the burst data subroutine. In this subroutine, the computer 8 stores the angle center of the burst data, the track center, the number of continuations, and the maximum value of the width direction dimension, and returns. The angle center and the width direction dimension are calculated based on the counting result of step S43.

As described above, the computer 8 detects the burst defect based on the data stored in the memory 11.

FIG. 21 shows a result of the burst defect inspection by the device of the present invention, which is a schematic diagram showing the disc-shaped information recording medium (optical disc) to be inspected and the burst defects existing on the information recording surface, and FIG. This is a list of burst defects that can be obtained.

In Fig. 21, "*" indicates a burst defect, numbers indicate sector numbers, "SIZE (max)" in Fig. 22 indicates the maximum width direction of the burst defect, and "TRACK (center)" indicates a burst defect. "TRACK (cross)" is the number of tracks that the burst defect straddles, "ANGLE (center)"
Is the angle of the center of the burst defect on the same basis as above,
“R” indicates the distance from the center.

〔The invention's effect〕

According to the method of the present invention as described above, it is possible to inspect a defect by one-time reproduction. It is also possible to combine many 1-bit defects into a defect block. Furthermore, since the size and position of the defective mass are stored, subsequent inspection with a microscope can be performed efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of the device of the present invention, and FIG.
FIG. 7 is a schematic diagram of a burst defect, FIG. 3 is a block diagram of a main part of a defect type detection unit, FIGS. 4 to 7 are timing charts of gate signals, FIG. 8 is a block diagram of a gate generation unit, and FIG. Is a format diagram of defect size type data, FIG. 10 is a code diagram of defect types, FIGS. 11 and 12 are flowcharts for determining defect types, FIG. 13 is a flowchart showing a processing procedure for classification into defective blocks, and FIG. Is a flow chart of the burst defect subroutine, FIG. 15 is a flow chart of the defect separation subroutine, FIG. 16 is a flow chart of the angle subroutine, FIG. 17 is a flow chart of the burst data subroutine, FIGS. FIG. 22 is a schematic diagram showing an example of inspection results, FIG. 22 is a list diagram showing the data, and FIG. 23 is a schematic diagram showing a disc-shaped information recording medium and burst defects existing thereon. FIG. 24 is a waveform diagram showing a dropout pulse, FIG. 25 is a block diagram showing a configuration example of a conventional defect inspection apparatus, FIG. 26 is a timing chart for explaining its operation, and FIG. 27 is an ISO standard optical disc. It is a block diagram of an information recording area. 3 ... Defect dimension information detection unit, 5 ... Control track error detection unit, 6 ... Address decoding / gate generation / header error detection unit, 7 ... Defect type detection unit, 8 ...
Computer, 9 ... Track position detection unit, 10 ... Angle / sector position information detection unit, 11 ... Memory In the drawings, the same reference numerals indicate the same or corresponding portions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Koji Shindo, 8-1-1 Tsukaguchihonmachi, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Corporation Industrial Systems Research Center

Claims (1)

(57) [Claims] 1. A means for detecting a defect by a reproduction signal from a disk-shaped information recording medium, a means for detecting the type of the detected defect, and a radial position and a circumferential position of the detected defect. Means, means for dividing defects into defect blocks based on the detected positions, means for calculating radial and circumferential dimensions of the defect blocks, and type, position and size of the detected defects or defect blocks A defect inspection apparatus for a disk-shaped information recording medium, comprising: