JPH056580A - Abnormal pit detection method and detection device - Google Patents

Abstract

PURPOSE:To count the number of abnormal pits on the entire surface of an optical disk by comparing the tracking error(TE) signal disturbance amplitude against a reference value. CONSTITUTION:When laser beams from a light pickup 2 are scanning the center of a pit, a TE signal becomes zero and when the beams move out of the center, it becomes light zero. By setting equation I, an abnormal pit is detected by the existence of a TE signal disturbance which is larger than a TE standard value. By doing this, the number of abnormal pits on the entire surface of the optical disk is counted. In the equation I, TE stands for an amplitude by a normal pit, TE' stands for an amplitude by an abnormal pit and TEref stands for a TE signal standard value.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and a device for detecting abnormal pits, and more particularly to a method and a device for detecting abnormal pits for checking a molded substrate of an optical disc.

[0002]

2. Description of the Related Art An optical disk is produced by transferring a stamper shape formed by mastering onto a substrate such as plastic and forming a layer of recording material on the substrate. Although there is a pre-format pit row on the stamper, since the size is as small as about 1 μm, the shape may not be correctly transferred onto the substrate, which may result in an abnormal pit. This is shown in FIG. That is, abnormal pits such as wall sagging and pit edge turning have occurred. Abnormal pits in the pre-formatted portion directly affect the signal quality of the optical disc, so it is necessary to check the substrate on which these abnormal pits exist by some method, but a method for detecting abnormal pits has not been clarified in the past.

Further, as shown in FIG. 15, as a characteristic of abnormal pits, there are many cases where the abnormal portion of the pit shape has a direction (inward or outward direction of the disc). Examining the occurrence distribution on the disk will give clues as to the cause of the occurrence of abnormal pits.

[0004]

An object of the present invention is to provide an abnormal pit detection method and a detection device using a tracking error signal (hereinafter referred to as a TE signal) obtained from an optical disk, and to detect the abnormal pit. The purpose is to accurately detect the angle of the abnormal pit, specify the position of the abnormal pit on the optical disc, and further determine the direction of the abnormal pit.

[0005]

In order to achieve the above object, the present invention provides (1)
The amplitude of the TE signal is compared with a reference value, and when the amplitude of the TE signal exceeds the reference value, it is regarded as an abnormal pit. Further, (2) in (1), the address part and the data part are distinguished from each other. , Only the address part is the target of the abnormal pit detection, and further, (3) the function of decoding the address part in the above (1) has a function to detect the address where the abnormal pit exists at the same time when the abnormal pit is detected. And even,
(4) It has a function of decoding the rotation angle and address of the optical disk, and at the same time as detecting the abnormal pit, detecting the angle and address on the optical disk where the abnormal pit exists, and (5) the rotation angle and the light of the optical disk. It has a function of decoding the position of the pickup, and at the same time as detecting the abnormal pit, detecting the angle and radius on the optical disc where the abnormal pit exists, or (6) having the function of determining the polarity of the tracking error signal, Simultaneously with the detection of the abnormal pit, the direction of the abnormal pit is determined, or (7) a TE signal generating circuit for extracting information on the optical disk by an optical pickup and receiving a signal from the optical pickup to generate a TE signal, A TE signal reference value generating circuit for generating a TE signal reference value for comparison with a TE signal from the TE signal generating circuit; And a comparison circuit for comparing the TE signal reference value with each other, and (8) in (7), an address for receiving a signal from the optical pickup and for distinguishing an address section from a data section. Section / data section identification circuit, a pulse generation circuit for inputting the output of the comparison circuit, an abnormal pit detection pulse from the pulse generation circuit, and the address section gate signal by the address section / data section identification circuit An AND gate circuit, and (9) in (7), an address section decoding circuit for receiving the signal from the optical pickup and decoding the address section, and a pulse generation for inputting the output of the comparison circuit. Circuit and the address decoded by the address decoding circuit is stored using the abnormal pit detection pulse from the pulse generation circuit as a write signal. That it consists of a memory, and further, in (10) (7),
An address section decoding circuit that receives a signal from the optical pickup and decodes an address section, an optical disk rotation angle decoding circuit, a pulse generation circuit that inputs the output of the comparison circuit, and an abnormal pit detection pulse from the pulse generation circuit By the address section decoding circuit and a memory for recording the address and the rotation angle decoded by the optical disk rotation angle decoding circuit. Further, (11) in (7), the signal from the optical pickup is received. An address section decoding circuit for decoding the address section, an optical disk rotation angle decoding circuit, a plurality of counters corresponding to the divided areas on the optical disk, a pulse generation circuit for inputting the output of the comparison circuit, and the address section Decoding circuit and optical disc rotation angle Before the address and rotation angle decoded by the decoding circuit A counter selection circuit that selects an appropriate counter from the counters, and counts the abnormal pit detection pulse from the pulse generation circuit to the counter selected by the counter selection circuit; and (12) above ( In 7), the optical pickup radial position decoding circuit, the optical disk rotation angle decoding circuit, a pulse generation circuit for inputting the output of the comparison circuit, and an abnormal pit detection pulse from the pulse generation circuit are used to decode the optical pickup radial position. And a memory for recording the radial position and the rotation angle decoded by the optical disk rotation angle decoding circuit, and (13) the optical pickup radial position decoding circuit in (7) above,
Optical disc rotation angle decoding circuit, a plurality of counters corresponding to the divided areas on the optical disc, a pulse generation circuit for inputting the output of the comparison circuit, the optical pickup radial position decoding circuit and the optical disc rotation angle decoding circuit A counter selection circuit that selects an appropriate counter from the counters according to the selected radial position and rotation angle, and counts an abnormal pit detection pulse from the pulse generation circuit in the counter selected by the counter selection circuit. It is characterized by. Hereinafter, description will be given based on examples of the present invention.

The TE signal is designed to be zero when the laser beam from the optical pickup scans the center of the pit, and nonzero when it is deviated from the center. The tracking servo circuit of the optical pickup controls the position of the laser beam so that the TE signal is always zero. However, a residual error occurs due to the characteristics of the servo circuit and the tilt of the optical disk. It is off center. Due to this slight displacement of the laser beam, even if the tracking servo is correctly performed on the normal pit, the TE signal is disturbed when the laser beam passes through the pit edge portion, and the amplitude is not zero. . This is shown in FIG. Further, the disturbance of the TE signal is significantly larger in the abnormal pit (the shape is not correctly transferred from the stamper) than in the normal pit (the shape is correctly transferred from the stamper), and is experimentally several times to 10 times as large as the normal pit. It was observed about twice. This is shown in FIG.

FIG. 1 is a block diagram for explaining an embodiment of an abnormal pit detection method and detection apparatus according to the present invention.
Is an optical disc, 2 is an optical pickup, 3 is a TE signal generation circuit, 4 is a TE signal reference value generation circuit, and 5 is a comparison circuit. Focusing on the amplitude of the disturbance of the TE signal, the reference value TEr
ef. Then, TE <TEref <TE '(TE: amplitude due to normal pit, TE': amplitude due to abnormal pit) is set, and an abnormal pit is detected by the presence of a TE signal disturbance larger than the TE reference value. Various measurements can be performed using the abnormal pit detection signal. For example, it is possible to know the number of abnormal pits on the entire surface of the optical disc by converting the abnormal pit detection signal into pulses and counting.

FIG. 2 is a diagram showing another embodiment of the method and apparatus for detecting abnormal pits according to the present invention. In the figure, 6 is a pulse generating circuit, 7 is an address part / data part identifying circuit, and 8 is an AND gate. , 9 are counters, and other parts having the same functions as those in FIG. 1 are denoted by the same reference numerals. In addition to the embodiment shown in FIG. 1, an address part / data part identification circuit 7 is provided, and the amplitude comparison of the TE signal is made effective only in the address part. The output of the comparison circuit 5 is input to the pulse generation circuit 6, and when an abnormal pit is detected, an abnormal pit detection pulse is generated. On the other hand, the address part / data part identification circuit 7 outputs an address part gate signal. The AND output of these two signals is an abnormal pit detection pulse in the address part and can be used for various measurements. In the embodiment of the present invention, by counting the output pulses of AND with the counter 9, only the abnormal pits in the address portion can be counted.

FIG. 3 is a diagram showing still another embodiment of the abnormal pit detection method and detection apparatus according to the present invention, in which 10
2 is an address decoding circuit, 11 is a memory, and the others are shown in FIG.
The same reference numerals are attached to the parts having the same functions as. Figure 1
In addition to the above embodiment, the address section decoding means 10 is provided to detect an address where an abnormal pit exists. The output of the comparison circuit 5 is input to the pulse generation circuit 6, and when an abnormal pit is detected, a pulse W is output to the memory 11.
R is output. On the other hand, the decoded address is output from the address decoding circuit 10 to the memory 11,
By writing the address output to the memory 11 as a write signal, the address at which the abnormal pit exists can be stored.

In the abnormal pit detection method described above, in order to specify the position on the optical disk where the abnormal pit exists, the position is estimated from the existing address by calculation. However, the position specification by calculation may not have sufficient accuracy for observation / analysis because the resolution in the angular direction is only one address. That is, it is unknown which part of one address has the abnormal pit. This is because one address is generally a circular arc of 10 degrees to several tens of degrees. On the other hand, since there are several to several tens of addresses in one track in the radial direction, sufficient accuracy can be obtained by calculation. Exist). An embodiment improved in view of this point will be described below.

FIG. 7 is a diagram showing another embodiment of the method and apparatus for detecting abnormal pits according to the present invention. In the figure, 21 is an optical disk, 22 is an optical pickup, 23 is a rotary encoder, and 24 is a TE signal generating circuit. , 25 is a TE signal reference value generation circuit, 26a is an address decoding circuit, 27 is a rotation angle decoding circuit, 28 is a comparison circuit, 29 is a pulse generation circuit, and 30a is a memory circuit. In addition to the embodiment of FIG. 1, the address decoding circuit 26a and the rotary encoder 2
3 and a rotation angle decoding circuit 27, and detects an address where an abnormal pit exists and an angle on the optical disk. The address decoding circuit 26a decodes the address of the optical disk being scanned by the optical pickup and stores it in the memory 30a.
Output to. The rotary encoder 23 is the optical disc 2
It rotates with 1 and outputs a pulse during rotation. A rotary encoder can obtain an angular resolution of about 0.1 °. The rotation angle decoding circuit 27 includes a rotary encoder 2
The pulses from 3 are counted and the rotation angle of the optical disc is output to the memory 30a.

The output of the comparison circuit 28 is the pulse generation circuit 2
9 and the pulse WR is output to the memory 30a when an abnormal pit is detected by the same method as in FIG.
When the abnormal pit is detected, the address output and the rotation angle output are written in the memory 30a by using WR as a writing signal to store the address where the abnormal pit exists and the angle on the optical disk. By calculating the radial position on the optical disk from the address among the data stored in the memory 30a and using it together with the angle data as shown in FIG. 11, the position on the optical disk where the abnormal pit exists can be specified.

FIG. 8 is a view showing still another embodiment of the abnormal pit detection method and detection apparatus according to the present invention, in which 30 is shown.
b counter selection circuit, C ₁ to Cn in a counter, and other portions of the same functions as Figure 7 are denoted by the same reference numerals. In this embodiment, as shown in FIG.
This is for knowing the number of abnormal pits in each area when divided. The output destinations of the address decoding circuit 26, the rotation angle decoding circuit 27, and the pulse generation circuit 29 are the counter selection circuit 30b.
b decodes the address output and the rotation angle output and selects the counter to be counted up. The counter n corresponds to the area n. When the abnormal pit is detected, the abnormal pit detection pulse UP is output from the pulse generation circuit 29 to the counter Cn selected by the counter selection circuit 30b.

FIG. 9 is a diagram showing still another embodiment of the abnormal pit detection method and detection apparatus according to the present invention, in which 26 is shown.
Reference numeral b is a radial position decoding circuit, reference numeral 31 is a linear encoder, and other parts having the same functions as those in FIG. The rotary encoder 23 rotates together with the optical disk 21, and outputs a pulse during rotation. The linear encoder 31 moves integrally with the optical pickup 22, and outputs a pulse while moving. 0.5-1.0μ with linear encoder
A resolution of about m can be obtained. Radial position decoding circuit 26b
Counts the pulses from the linear encoder and stores the radial position (on the optical disk) of the optical pickup in the memory 30a.
Output to. The rotation angle decoding circuit 27 counts the pulses from the rotary encoder 23 and outputs the rotation angle of the optical disc to the memory 30a.

The output of the comparison circuit 28 is the pulse generation circuit 2
9 and the pulse WR is output to the memory 30a when an abnormal pit is detected by the same method as in FIG.
When the abnormal pit is detected, the radius position output and the rotation angle output are written in the memory 30a by using WR as a writing signal to store the radius and the angle on the optical disc in which the abnormal pit exists. The position on the optical disc where the abnormal pit exists can be specified from the data stored in the memory 30a.

[0016] Figure 10 is a diagram showing still another embodiment of the abnormality pit detecting method and detecting apparatus according to the present invention, 30b counter selection circuit, C ₁ to Cn in the counter, other,
The parts having the same functions as those in FIG. 7 are designated by the same reference numerals.
The linear encoder 31 is provided in the optical pickup 22, and the radial position is output via the radial position decoding circuit 26b. The other operation is to know the number of abnormal pits in each area on the entire surface of the optical disk divided into n as in FIG.

FIG. 13 is a diagram showing still another embodiment of the abnormal pit detection method according to the present invention. In the figure, 41 is an optical disk, 42 is an optical pickup, 43 is a rotary encoder, 44 is a linear encoder, and 45a is TEref.
(+) Generation circuit, 45b is a TEref (-) generation circuit,
46 is a TE signal generating circuit, 47 is a radial position decoding circuit, 4
8 is a rotation angle decoding circuit, 49 is a comparison circuit, 50a is a pulse generation circuit (+), 50b is a pulse generation circuit (-), 5
Reference numeral 1 is a mask signal generation circuit, 52a and 52b are AND gate circuits, and 53 is a data processing circuit.

The rotation angle decoding circuit 48 includes the pickup 4
The focal angle position of No. 2 is decoded by the rotary encoder 43, and the rotation angle signal is output to the data processing circuit 54.
The radial position decoding circuit 47 decodes the focal position of the pickup 42 from the linear encoder 44 and outputs a radial position signal to the data processing circuit 54. The TE signal generation circuit 46 receives a signal from the optical pickup 42 and outputs a TE signal, and the TEref generation circuits 45a and 45b output a TE signal reference value for detecting an abnormal pit. The comparison circuits 49a and 49b output the comparison results of the both to the pulse generation circuits 50a and 50b. However, when the TE signal exceeds TEref as a result of the comparison, the pulse generation circuits 50a and 50b.
b outputs an abnormal pit detection pulse.

By the way, FIG. 16 shows the TE of the abnormal pit portion.
Although the signal is shown, since the polarity of the TE signal is different in the direction of the abnormal portion, that is, in the inner peripheral direction and the outer peripheral direction,
By distinguishing the abnormal pit detection pulse detected at the abnormal pit entry portion b, it is possible to determine whether the abnormal direction of the abnormal pit is inward or outward. In FIG. 16, the reference values TEref (+) and TEref (−) are respectively set to TE (+) <TEref (+) <TE (+) ′ TE (−)> TEref (−)> TE (−) ′. Set. The abnormal pit detection pulse is output even at the abnormal pit escape portion c, but in this embodiment, a mask signal generation circuit 51 is provided as a method of distinguishing the detection pulse, and the mask signal is output at the same time when the abnormal pit detection pulse at the time of pit entry occurs. The AND gate circuits 52a and 52b can output and output the abnormal pit detection pulse at the pit escape portion.

When an abnormal pit is detected, the abnormal pit detection pulse is output to the data processing circuit 53 in a state in which the abnormal direction is discriminated between the inner peripheral direction and the outer peripheral direction, and the rotation angle signal and the radial position signal are output. At the same time, it is written in the memory and the number of abnormal pits is also counted. FIG. 14 shows a simplified diagram for explaining an example of the result of the inspection according to the embodiment of the present invention (FIG. 13). In this way, not only the exact position and number of abnormal pits on the disc can be known, but also the direction of the abnormal pits and their distribution on the disc can be grasped.

[0021]

As is apparent from the above description, the present invention has the following effects. (1) Effects corresponding to claims 1 and 7: Abnormal pits can be detected by using the TE signal, and it becomes possible to count the abnormal pits over the entire surface of the optical disc. (2) Effects corresponding to claims 2 and 8: In the write once (WO; Write Once) type that can be written only once or the rewritable (RW) type that can be rewritten, the address part and the data part are distinguished. Generally, the pre-format pit exists only in the address part. In this type, the area for detecting abnormal pits is necessary and sufficient only in the address section, and if the abnormal pit detection function works in the data section as well, it is possible to erroneously detect irregularity in the amplitude of the TE signal due to defects as abnormal pits. There is a nature. Further, since the address part and the data part are identified and the amplitude comparison of the TE signal is performed only in the address part, W
An abnormal pit of an O / RW type optical disc can be detected stably without being affected by defects. (3) Effects corresponding to claims 3 and 9: Since the existence address can be specified at the same time when the abnormal pit is detected,
This has an effect that observation and distribution of abnormal pits can be easily performed. (4) Effects corresponding to claims 4, 10 and 11: Since the angle at which the abnormal pit exists can be detected accurately and the radial position can also be known, the position where the abnormal pit exists on the optical disc can be accurately measured. Can be specified. Therefore, there is an effect that the abnormal pits can be observed and analyzed accurately. (5) Effects corresponding to claims 5, 12, and 13: In addition to accurately detecting the angle at which the abnormal pit exists, the radial position at which the abnormal pit exists can be known regardless of the presence or absence of an address. Address does not exist /
Alternatively, it is possible to accurately specify the abnormal pit existence position on the optical disc that cannot be explained. Therefore, there is an effect that the abnormal pits can be observed and analyzed accurately. (6) Effect corresponding to claim 6: The function of judging the polarity of the TE signal is provided, and since the direction of the abnormal pit can be judged at the same time as the abnormal pit is detected, the cause of the abnormal pit can be effectively analyzed. .

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a method and a device for detecting abnormal pits according to the present invention.

FIG. 2 is a diagram showing another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 3 is a view showing still another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 4 is a diagram for explaining a disorder of a tracking error signal.

FIG. 5 is a diagram for explaining normal pits and abnormal pits.

FIG. 6 is a diagram showing a state of abnormal pits.

FIG. 7 is a view showing still another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 8 is a diagram showing still another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 9 is a diagram showing still another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 10 is a diagram showing still another embodiment of the abnormal pit detection method and detection device according to the present invention.

FIG. 11 is a diagram for explaining specifying a position on an optical disc where an abnormal pit exists.

FIG. 12 is a diagram for explaining the number of abnormal pits in each area where the entire surface of the optical disc is divided into n.

FIG. 13 is a diagram showing still another embodiment of the abnormal pit detection method according to the present invention.

FIG. 14 is a diagram showing an example of a result of inspection.

FIG. 15 is a diagram showing a shape of an abnormal pit.

FIG. 16 is a diagram showing a TE signal in an abnormal pit.

[Explanation of symbols]

1 ... Optical disc, 2 ... Optical pickup, 3 ... Tracking error signal (TE signal) generation circuit, 4 ... Tracking error signal (TE signal) reference value generation circuit, 5 ... Comparison circuit.

Claims (13)

[Claims] 1. A method for detecting abnormal pits, which comprises comparing the amplitude of a tracking error signal with a reference value, and if the amplitude of the tracking error signal exceeds the reference value, it is regarded as an abnormal pit. 2. The abnormal pit detection method according to claim 1, wherein the address part and the data part are distinguished from each other, and the abnormal pit detection is performed only in the address part. 3. The abnormal pit detection method according to claim 1, wherein the abnormal pit detection method has a function of decoding the address portion, and simultaneously detects an abnormal pit and also detects an address where the abnormal pit exists. 4. The abnormal pit according to claim 1, which has a function of decoding the rotation angle and the address of the optical disk, and detects the angle and the address on the optical disk where the abnormal pit exists at the same time when the abnormal pit is detected. Detection method. 5. The optical disc according to claim 1, which has a function of reading the rotation angle of the optical disc and the position of the optical pickup, and at the same time detecting the abnormal pit, detecting the angle and the radius on the optical disc where the abnormal pit exists. Abnormal pit detection method. 6. The abnormal pit detection method according to claim 1, which has a function of determining the polarity of the tracking error signal and determines the direction of the abnormal pit at the same time when the abnormal pit is detected. 7. A tracking error signal generating circuit for extracting information on an optical disk by an optical pickup, receiving a signal from the optical pickup and generating a tracking error signal, and comparing the tracking error signal from the tracking error signal generating circuit. For detecting the tracking error signal reference value, and a comparison circuit for comparing the tracking error signal with the tracking error signal reference value. . 8. A signal from the optical pickup is received,
Address part / data part identifying circuit for distinguishing the address part from the data part, a pulse generating circuit for inputting the output of the comparing circuit, an abnormal pit detection pulse from the pulse generating circuit, and the address part / data part identifying circuit 8. An abnormal pit detection device according to claim 7, further comprising an AND gate circuit for ANDing the gate signal of the address portion by the AND gate circuit. 9. A signal from the optical pickup is received,
An address section decoding circuit for decoding the address section, a pulse generation circuit for inputting the output of the comparison circuit, and a memory for storing the address decoded by the address section decoding circuit by an abnormal pit detection pulse from the pulse generation circuit. 8. The abnormal pit detection device according to claim 7, comprising: 10. An address section decoding circuit that receives a signal from the optical pickup and decodes an address section, an optical disk rotation angle decoding circuit, a pulse generation circuit that inputs the output of the comparison circuit, and the pulse generation circuit. 8. The abnormal pit detection device according to claim 7, wherein the abnormal pit detection pulse comprises a memory for recording the address and the rotation angle decoded by the address section decoding circuit and the optical disk rotation angle decoding circuit. 11. An address section decoding circuit which receives a signal from the optical pickup and decodes an address section, an optical disk rotation angle decoding circuit, a plurality of counters corresponding to divided areas on the optical disk, and the comparison circuit. And a counter selection circuit for selecting an appropriate counter from the counters according to the address and the rotation angle decoded by the address section decoding circuit and the optical disk rotation angle decoding circuit. The abnormal pit detection device according to claim 7, wherein the abnormal pit detection pulse from the circuit is counted by a counter selected by the counter selection circuit. 12. An optical pickup radial position decoding circuit,
The optical disk rotation angle decoding circuit, the pulse generation circuit for inputting the output of the comparison circuit, and the radius read by the optical pickup radius position decoding circuit and the optical disk rotation angle decoding circuit by the abnormal pit detection pulse from the pulse generation circuit. 8. The abnormal pit detection device according to claim 7, further comprising a memory for recording a position and a rotation angle. 13. An optical pickup radial position decoding circuit,
Optical disc rotation angle decoding circuit, a plurality of counters corresponding to the divided areas on the optical disc, a pulse generation circuit for inputting the output of the comparison circuit, the optical pickup radial position decoding circuit and the optical disc rotation angle decoding circuit A counter selection circuit that selects an appropriate counter from the counters according to the selected radial position and rotation angle, and counts an abnormal pit detection pulse from the pulse generation circuit in the counter selected by the counter selection circuit. The abnormal pit detection device according to claim 7.