JPH07141702A - Optical disk inspecting device - Google Patents

Abstract

PURPOSE:To detect desired fine defects without recording and reproducing signals in a separate state by setting a variable slice level linked with a base line light quantity for the photodetection signal of a laser beam. CONSTITUTION:The laser beam from a laser beam source 1 is detected by a photodetector 4 via a converging lens 2 and an optical disk 3 and the defect detection is executed by a means 5. A photodetector light quantity signal 10 detected by the photodetector 4 is inputted to a base line light quantity judging circuit 14 in a defect detecting means 5. The light quantity level of the deflectless part of the optical disk is judged within this circuit 14 and a signal is sent as the base line light quantity to a slice level setting circuit 15. The fluctuating slice level is set in accordance with the base line light quantity and the bright slice level and dark slice level are sent to the defect detecting circuit 16. The dark defect and bright defect are detected by using the bright slice level and dark slice level for the photodetector light quantity signal 10 in this circuit 16.

Description

Detailed Description of the Invention

A detailed description of the present invention will be given in accordance with the following items.

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc inspection apparatus.

[0003]

2. Description of the Related Art An optical disk inspection apparatus will be described below with reference to the drawings.

FIG. 2 shows the structure of a basic optical disk inspection apparatus, and FIGS. 14, 15 and 16 show waveforms in the process of detecting a defect of an optical disk by the defect detecting means 5.

In FIG. 2, a laser light source 1 for generating a laser beam for irradiating the optical disc 3,
It is composed of a converging lens 2 for converging a laser beam on the optical disc 3, a light receiving element 4 for receiving the laser beam transmitted through the optical disc 3, and a defect detecting means 5 for processing a light reception signal of the laser beam transmitted through the optical disc 3. Was there.

[0006]

However, in the optical disc inspection, it is difficult to detect fine defects stably without erroneous detection due to the influence of fluctuations in transmittance in the optical disc.

The problems in the defect detecting means 5 will be described below.

As can be seen from FIG. 14, a varied laser beam light amount 10 (hereinafter referred to as a baseline light amount) may be obtained even in an area which is not a defective portion of an optical disk, and a case where a bright defect 21 occurs. However, the bright defect 21 could not be detected at the bright slice level 22 because it was hidden in the fluctuation range of the baseline light amount. Similarly, the dark defect 20 cannot be detected at the dark slice level 24.

Further, the pit area bright defect 91 as shown in FIG. 15 has a smaller amount of received light than the mirror level and the land level, and therefore the defect cannot be detected at the bright slice level 22. Similarly, since the groove area dark defect 90 and the mirror area dark defect 92 have a larger amount of received light than the pit level, it is impossible to detect the defect at the dark slice level 24.

Further, as shown in FIG. 16, in the user area, the user area bright defect 129 is not detected at the user area bright defect slice level 123,
The user area bright defect 127 is detected. Similarly, the user area dark defect 130 is not detected at the user area dark defect slice level 124, and the user area dark defect 128 is detected at the user area dark defect slice level 124. However, the management area bright micro-defects 125 generated in a data area (hereinafter, referred to as a management area) which is to be particularly strictly inspected cannot be detected at the user bright defect slice level 123. Similarly, the management area dark fine defects 126 are the user dark defect slice level 1
The defect detection signal 13 obtained cannot be detected by 24.
Only the defect indicated by 3 will be detected.

Therefore, if a strict bright slice level 131 is set in order to detect fine defects, the management area bright fine defects 125 can be detected, but at the same time, the user area bright is not required to be detected. The fine defects 129 are detected. Similarly, when the strict dark slice level 132 is set, the management area dark fine defects 1
Although it is possible to detect 26, the user area dark microscopic defect 130, which does not require detection at the same time, is detected, and the defect detection signal obtained is 134.

Therefore, in order to deal with such a problem,
Finally, in a separate inspection, as a practical use inspection, it was inevitable to detect a defect by recording and reproducing a signal and comparing the basic signal and the reproduced signal.

Therefore, the present invention solves the above-mentioned problems, and an object thereof is to improve the ability to detect a target fine defect without recording or reproducing a signal in a separate step. It is in.

[0014]

Means for Solving the Problems (1) A laser light source for generating a laser beam for irradiating an optical disc, a converging lens for converging the laser beam on the optical disc, and a laser beam light amount changed by the optical disc. In an optical disc inspection apparatus including a light-receiving element and a device for processing a light-receiving signal of a light-receiving element that receives a laser beam light amount, a variable slice level linked to the baseline light amount is set for the laser beam light-receiving signal to detect defects. It was possible to do.

(2) In the inspection device of (1), it is possible to detect defects by setting a fluctuating slice level corresponding to a change in the baseline light amount in an optical disc in which the baseline light amount fluctuates. Is.

(3) In the inspection apparatus of (1), even if there is no defect in the optical disc, the slice level of the laser beam received by the light receiving element differs depending on the preformat area. Is set to detect defects.

(4) In the inspection device of (1), the inspection device requires different inspection levels depending on the area in the same optical disk, and at least two or more depending on the area for the received light signal of the laser beam receiving element. By providing the defect detection slice level of, it is possible to have different inspection levels depending on the area.

[0018]

In the present invention, since the fine defect which is buried in the change in the baseline light amount is detected, the fine defect can be detected by using the variable slice level corresponding to the change in the baseline light amount.

Further, in order to detect fine defects buried in the difference in the baseline light amount depending on each premaster area of the optical disc, different slice levels are set for each premaster area. It is possible to detect minute defects that are buried in the line light amount.

In addition, according to the area in the same optical disc,
In order to detect non-detection of defects that do not require detection and to detect micro defects that require detection, by providing different slice levels depending on the area, it is possible to detect only defects that require detection.

[0021]

【Example】

(Embodiment 1) In the embodiment 1, according to the variation of the laser beam light quantity by the optical disk of claim 1 and the variation of the baseline light quantity, the slice level for defect detection is adjusted to the variation of the baseline light quantity, An example in which the defect detection is performed based on the variable slice level will be described.

Embodiments of the present invention will be described below with reference to the drawings. 2 is a block diagram of a basic transmission type optical disc inspection apparatus, FIG. 3 is a circuit block diagram of the defect detecting means of FIG. 2, and FIG. 4 is a signal waveform in the defect detecting means of FIG.

In FIG. 2, a laser light source 1 for generating a laser beam for irradiating the optical disc 3, a converging lens 2 for converging the laser beam on the optical disc 3, an optical disc 3, and a laser beam transmitted through the optical disc 3 are received. The light receiving element 4 is composed of a defect detecting means 5 for detecting a defect from a signal received by the light receiving element 4.

Inside the defect detecting means 5, as shown in FIG. 3, the light receiving element light amount signal 10 detected by the light receiving element 4 is
It is input to the baseline light amount determination circuit 14, and the light amount level of the defect-free portion of the optical disc is determined in the baseline light amount determination circuit 14, and a signal is sent to the slice level setting circuit 15 as the baseline light amount. The slice level setting circuit 15 sets a slice level that has changed based on the baseline light amount, and sends the bright slice level 22 and the dark slice level 24 shown in FIG. 4 to the defect detection circuit 16. In the defect detection circuit 16, the dark defect 20 and the bright defect 21 are detected by multiplying the light receiving element light amount signal 10 by the bright slice level 22 and the dark slice level 24.

FIG. 4 shows the signal waveforms that can be confirmed inside the defect detection circuit 16. The light slice level 22 that has changed and the dark slice level 24 that has changed are received with respect to the change in the baseline light amount. It can be confirmed that the dark defect 20 and the bright defect 21 can be detected stably by applying the element light amount signal 10.

Furthermore, by synchronizing the light receiving element light amount signal 10 with the bright slice level 22 and the dark slice level 24, it is possible to detect defects with higher accuracy.

Further, in detecting the defect, the embodiment has been described in which the bright defect slice level and the dark defect slice level are used in combination. However, even if the inspection device uses either one, the intention of the present invention is not limited. It is possible to detect a defect by setting a variable slice level to be set.

(Embodiment 2) In Embodiment 2, a variable slice level corresponding to a change in the baseline light quantity due to a change in the light quantity due to the change in the optical disc transmittance of claims 1, 2 and 3 is adopted. , For optical disks that show different transmittance depending on the pre-formatted area of the optical disk,
An example of defect detection in which different slice levels are set for each area will be described.

Embodiments of the present invention will be described below with reference to the drawings. 5 is an external view of an optical disc, FIG. 2 is a block diagram of a basic transmission type optical disc inspection apparatus, and FIG.
3 is a circuit block diagram of the defect detecting means of FIG. 2, and FIG. 1 is FIG.
3 shows a signal waveform in the defect detecting means of FIG.

FIG. 5 shows the appearance of the optical disc. The optical disc 43 is composed of pre-format areas including a groove area 40, a pit area 41, and a mirror area 42. At the time of performing a defect inspection, the light amount received by the light receiving element 4 has different transmittances in the respective pre-format areas. The light amount of the laser beam affected by the transmittance of each preformat area is incident on the light receiving element 4. Therefore, when the optical disc inspection is executed, various reflected light amounts are incident on the light receiving element 4 without being limited to the occurrence of defects.

FIG. 2 is a block diagram of a transmission type optical disc inspection apparatus. Since the configuration is the same as that of the first embodiment, the description thereof is omitted here.

The inside of the defect detecting means 5 is composed of the blocks shown in FIG. 13, and the light receiving element light amount signal 10 detected by the light receiving element 4 is input to the baseline light amount judging circuit 150, and inside the baseline light amount judging circuit 150. Then, the mirror area baseline light intensity 1 of the part of the optical disc where there is no defect
57, the groove area base line light amount 158 and the pit area base line light amount 159 are determined, and the respective mirror area, groove area and pit area signals 156 are determined.
To the slice level switching gate circuit 154.

On the other hand, on the basis of the mirror level baseline light quantity 157 set by the base line light quantity judging circuit 150, the mirror slice level setting circuit 151
The variable bright slice level 141A and the variable dark slice level 142A at the mirror level shown in (a) are set,
A signal is sent to the slice level switching circuit 154.

Similarly, the base line light amount judgment circuit 150
Land level baseline light intensity 158 set by
In the present embodiment, the land slice level setting circuit 152 uses the land level in FIG.
The variable bright slice level 141C and the variable dark slice level 142C at the land level shown in (b) are set,
A signal is sent to the slice level switching circuit 154.

Similarly, the base line light amount judgment circuit 150
The pit slice level setting circuit 153 sets the variable bright slice level 141B and the variable dark slice level 142B at the pit level as shown in FIG. A signal is sent to the level switching circuit 154.

Slice level switching gate circuit 15
In 4, the determination was made by the baseline light amount determination circuit 150,
Based on the area signal 156, the variable bright slice level 141A in the mirror area, the varying dark slice level 142A, the varying bright slice level 141B in the pit area, the varying dark slice level 142B, and the varying bright slice in the land level shown in FIG. The level 141C and the varying dark slice level 142C are selected, the varying bright slice level 141 and the varying dark slice level 142 are set, and a signal is sent to the defect detection circuit 155.

In the defect detection circuit 155, the variable light slice level 141 and the variable dark slice level 142 are applied to the light receiving element light amount signal 10 as shown in FIG. Therefore, at the variable bright slice level 141, it becomes possible to detect the pit light fine defects 144, the mirror light fine defects 147, and the land light fine defects 143, and the bright defect signal 149A is obtained. Similarly, the light receiving element light amount signal 10
On the other hand, in the variable dark slice level 142, it becomes possible to detect defects of the pit dark fine defects 146, the land dark fine defects 145, and the mirror dark fine defects 148, and the dark defect signal 1
49B is obtained.

Therefore, the defect signal 149 can be obtained as the sum of the bright defect signal 149A and the dark defect signal 149B.

Further, the slice level switching circuit 154
By adjusting the slice level switching timing of, the defect can be detected more stably.

Further, in detecting the defect, the embodiment has been described by using the bright defect slice level and the dark defect slice level together, but even if the inspection apparatus uses either one, the intention of the present invention is as follows. It is possible to detect a defect by a slice level obtained by combining variable slice levels of different slice levels.

(Third Embodiment) In the third embodiment, the defect detection adopting two or more slice levels corresponding to the change in the amount of reflected light due to the change in the amount of reflected light due to the preformatted states of claims 1 and 3. An example will be described.

Embodiments of the present invention will be described below with reference to the drawings. 5 is an external view of an optical disc, FIG. 6 is a basic configuration diagram of a reflection type optical disc inspection apparatus, FIG. 7 is a circuit block diagram of the defect detecting means 5 of FIG. 6, and FIG. 8 is a defect detecting means of FIG. The signal waveform of is shown.

FIG. 5 shows the appearance of an example of an optical disc. The optical disc is composed of preformatted areas including a groove area 40, a pit area 41, and a mirror area 42. At the time of performing a defect inspection, the light amount received by the light receiving element 4 is different because the preformatted areas have different reflectances. The amount of reflected light that is affected by the reflectance of the pre-formatted area is incident on the light receiving element 4. Therefore, when the optical disc inspection is executed, various reflected light amounts are incident on the light receiving element 4 without being limited to the occurrence of defects.

FIG. 6 is a block diagram of a reflection type optical disc inspection apparatus, which includes a laser light source 1 for generating a laser beam for irradiating the optical disc 3, a converging lens 2 for converging the laser beam on the optical disc 3, an optical disc 3, From the beam splitter 6 for reflecting the laser beam reflected from the optical disk to the light receiving element 4, the light receiving element 4 for receiving the laser beam reflected from the optical disk, and the defect detecting means 5 for detecting a defect from the signal received by the light receiving element 4. Composed.

The inside of the defect detecting means 5 is composed of the circuit block shown in FIG. 7, and the light receiving element light amount signal 10 detected by the light receiving element 4 is input to the baseline light amount judging circuit 72, and the baseline light amount judging circuit 72. Among them, the mirror area baseline light quantity, the groove area baseline light quantity, and the pit area baseline light quantity of the defect-free portion of the optical disc are determined, and a signal is sent to the slice level switching gate circuit 73 as the respective baseline light quantities.

Slice level switching gate circuit 73
Then, the mirror area gate signal 64 based on the mirror area baseline light quantity, the groove area gate signal 63 based on the groove area baseline light quantity, and the pit area gate signal 6 based on the pit area baseline light quantity.
2, respectively, and the mirror level defect gate circuit 7
7. Land level defective gate circuit 78 (In the present description, assuming that tracking is performed on land in the groove area, the signal level will be input to the light receiving element 4 as a land level for the sake of description. When the tracking is performed in the in-groove, the obtained signal level becomes the groove level.), And the signal is sent to the pit level defect gate circuit 79.

Next, the operation of the defect detection circuit and the defect gate circuit will be described with reference to FIG.

In the mirror level defect detection circuit 74, the input of the light receiving element light amount signal 10 is compared with the mirror area bright defect slice level 81 and the mirror area dark defect slice level 82 to perform defect detection. However,
At this point, the mirror area dark defect slice level 82 causes the non-defective groove area 40 and pit area 4
The whole area of 1 will be detected as a defect. Therefore, the mirror level defect gate circuit 77 causes the mirror level defect detection signal 65 and the mirror area defect detection gate signal 6 to be detected.
By obtaining the product of 4, the mirror area defect detection signal 68
As a signal of only the defect in the mirror area can be obtained.

Similarly, the land level defect detection circuit 75 performs defect detection by comparing the input of the light receiving element light amount signal 10 with the groove area bright defect slice level 83 and the groove area dark defect slice level 84. However, at this point, the entire non-defective mirror area 42 is detected as a defect by the groove area bright defect slice level. Further, the entire groove area dark defect slice level 84 also detects the entire non-defective pit area 41 as a defect. Therefore,
By obtaining the product of the land level defect detection signal 66 and the land area defect detection gate signal 63 by the land level defect gate circuit 78, only the groove area defect signal can be obtained as the groove area defect detection signal 69.

Similarly, the pit level defect detection circuit 76 compares the input of the light receiving element light amount signal 10 with the pit area bright defect slice level 85 and the pit area dark defect slice level 86 to detect a defect. However, at this point, the mirror area 42 and the groove area 40 are changed by the pit area bright defect slice level 85.
Therefore, the product of the pit level defect detection signal 67 and the pit area defect detection gate signal 62 is obtained by the pit level defect gate circuit 79 as the pit area defect detection signal 70 of the pit area. Only the defect signal is obtained.

Further, by adjusting the gate signal generation timing of the slice level switching gate circuit 73, the defect can be detected more stably.

Further, in detecting the defect, the embodiment is described by using the bright defect slice level and the dark defect slice level together. However, even if it is an inspection apparatus using either one, the intention of the present invention is obtained. It is possible to set different slice levels to detect defects.

(Fourth Embodiment) In the fourth embodiment, in the inspection device according to the first and the fourth embodiments, which requires different slice levels depending on the area in the same optical disk, the received signal of the laser beam receiving element is An embodiment in which defect detection is performed by providing at least two defect detection slice levels will be described.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 9 is an example of the appearance of an optical disc showing area division for optical discs that require different inspection slice levels, FIG. 10 is the configuration of a basic reflection type optical disc inspection device, and FIG. 11 is a circuit block diagram of defect detection means. 12 shows signal waveforms in the defect detection circuit of FIG.

The optical disc shown in FIG. 9 has a management area 10
0 and the user area 101.

The structure of the reflection type optical disc inspection apparatus shown in FIG. 10 includes a laser light source 1 for generating a laser beam for irradiating the optical disc 3, a converging lens 2 for converging the laser beam on the optical disc 3, and an optical disc 3. A beam splitter 6 for reflecting the laser beam reflected from the optical disk 3 to the light receiving element 4, a light receiving element 4 for receiving the laser beam reflected from the optical disk 3, and a light receiving element 4 It is composed of a defect detection circuit 5 for detecting a defect from a signal received by and a scanning position detecting means 7 for detecting an inspection position on the optical disc 3.

Next, the operation will be described with reference to the drawings.

The inside of the defect detecting means 5 is composed of the circuit block shown in FIG. 11, and the scanning position signal 110 detected by the scanning position detecting means 7 is inputted to the scanning position detecting circuit 112, and the inside of the scanning position detecting circuit 112 is shown. Then, the inspection position of the optical disk is determined, and the scanning position information 113 for setting by the slice level setting circuit 114 is generated. In the slice level setting circuit 114, a management area bright defect slice level 121 and a management area dark defect slice level 122 are respectively set during scanning of the management area 100 based on the scanning position information 113, and the defect detection circuit 116 is set in the management area. The defect level is set for the slice level of 100 and the defect detection is performed on the light receiving element light amount signal 10 detected by the light receiving element 4, and the management area fine bright defect 125 is detected by the management area bright slice level 121. Further, the management area dark slice level 122 enables defect detection of the management area fine dark defect 126.

On the other hand, while scanning the user area 101, the user area bright defect slice level 123 and the user area dark defect slice level 124 are set respectively, and are set as the slice level of the user area 101 in the defect detection circuit 116, and the light receiving element is set. The defect detection is performed on the light receiving element light amount signal 10 detected in step 4, and the user area bright defect 127 is detected by the user area bright defect slice level 123.
Is detected. Further, the user area dark defect slice level 124 detects the user area dark defect 128.

Therefore, in this inspection, in the management area, the management area fine bright defect 125 and the management area fine dark defect 126 are detected by the severe slice level, the management area bright defect slice level 121, and the management area dark defect slice level 122. it can. On the other hand, in the user area, since the rough slice level, the user area bright defect slice level 123, and the user area dark defect slice level 124 are set, the user area bright defect 127 and the user area dark defect 128 are detected, but the user The area fine bright defect 129 and the user area fine dark defect 130 are not detected, and the defect detection signal 117 is obtained.

In the fourth embodiment, the management area 100 and the user area 101 have been described as an example, but the present invention is not limited to concentric area division, and at least two areas are provided.
Defects are detected by using different slice levels for three or more areas.The area is a radial area division, a concentric circle and a radial combination, or a square not depending on the above. It can also be used in other areas.

Further, in detecting the defect, the embodiment has been described in which the bright defect slice level and the dark defect slice level are used in combination. It is possible to set different slice levels to detect defects.

[0063]

As described above, according to the present invention, when inspecting an optical disc, different slice levels are provided for the variable slice level or the pre-formatted area of the optical disc, or different slice levels are provided for different areas of the optical disc. By setting the level, the following effects can be obtained.

By using the variable slice level when inspecting the optical disk 3, it is possible to stably detect the fine defects buried in the fluctuation of the baseline light amount with good reproducibility.

Further, by providing different slice levels depending on the preformat area of the optical disc,
It is possible to detect an undetectable defect that is buried in the fluctuation of the baseline light amount due to the pre-formatting of the optical disc.

Further, when different inspection levels are set for a plurality of areas of the optical disk, the inspection is performed using different inspection levels corresponding to the areas. It is possible to inspect at the inspection level.

[Brief description of drawings]

FIG. 1 is a defect detection waveform diagram using a variable slice level according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a basic transmission type inspection apparatus for inspecting a defect of an optical disc which is an embodiment of the present invention.

FIG. 3 is a block diagram of an inspection apparatus using a variable slice level of an optical disc according to an embodiment of the present invention.

FIG. 4 is a defect detection waveform diagram when a variable slice level according to an embodiment of the present invention is used.

FIG. 5 is an external view of an optical disc used as an example that is an embodiment of the present invention.

FIG. 6 is a configuration diagram of a basic reflection type inspection apparatus for inspecting a defect of an optical disc according to an embodiment of the present invention.

FIG. 7 is a block diagram of an inspection apparatus using a slice level switching function of an optical disc according to an embodiment of the present invention.

FIG. 8 is a defect detection waveform diagram for performing defect detection using slice level switching according to an embodiment of the present invention.

FIG. 9 is an external view of an optical disc showing a management area and a user area used as an example that is an embodiment of the present invention.

FIG. 10 is a configuration diagram of a basic reflection type inspection apparatus for inspecting a defect of an optical disc according to an embodiment of the present invention.

FIG. 11 is a block diagram of an inspection apparatus using a slice level switching function according to a disk inspection position in an embodiment according to the present invention.

FIG. 12 is a defect detection waveform diagram in which defect detection is performed using slice level switching according to the optical disc position in the embodiment according to the present invention.

FIG. 13 is a block diagram of an inspection apparatus using a slice level switching function according to a preformatted area of an optical disc in an embodiment according to the present invention.

FIG. 14 is a defect waveform diagram which is buried in a baseline fluctuation in the example of the conventional inspection apparatus.

FIG. 15 is a defect waveform diagram which is buried in a preformatted signal of an optical disc in an example of a conventional inspection apparatus.

FIG. 16 is a defect waveform diagram showing a problem when the same slice level is used in the embodiment of the conventional inspection apparatus.

[Explanation of symbols]

 1: Laser light source 2: Converging lens 3: Optical disk 4: Light receiving element 4 5: Defect detection circuit 6: Beam splitter 10: Light receiving element light amount signal input 141: Fluctuating bright slice level 142: Fluctuating dark slice level 147: Mirror area Bright defect 148: Mirror area dark defect 143: Groove area bright defect 145: Groove area dark defect 144: Pit area bright defect 146: Pit area dark defect 149: Defect detection signal

Claims (4)

[Claims] 1. A laser light source for generating a laser beam for irradiating an optical disc, a converging lens for converging the laser beam on the optical disc, a light receiving element for receiving the laser beam light amount changed by the optical disc, and a laser beam light amount. An optical disc inspecting device, comprising: a device for processing a light receiving signal of a light receiving element that has received a light beam, wherein a variable slice level is set for the light receiving signal of the laser beam to detect a defect. 2. The inspection apparatus according to claim 1, wherein in the optical disc in which the light amount of the laser beam received by the light receiving element fluctuates even in a defect-free portion, a fluctuating slice level corresponding to a change in the laser beam light amount in the defect-free portion is set. Then, an optical disc inspection apparatus characterized by performing defect detection. 3. The inspection apparatus according to claim 1, wherein even for an optical disk having no defect, an independent slice level is set for each area of the disk having a different amount of light received by the laser beam of the light receiving element depending on the area, and a defect level is set. An optical disk inspection device characterized by performing detection. 4. The inspection apparatus according to claim 1, wherein the inspection apparatus requires different inspection levels depending on areas within the same optical disc, and at least two or more defect detection slices are provided for a light reception signal of a laser beam light receiving element. An optical disk inspection device characterized by providing a level.