JP2001141666A - Optical disk defect inspection device - Google Patents

Abstract

(57) [Problem] To provide an optical disk defect inspection device capable of calibrating a device so as to perform a defect inspection more appropriately by providing a configuration for generating a pseudo defect signal for more accurate device calibration in the defect inspection device itself. provide. SOLUTION: A defect inspection apparatus for an optical disk is provided with a CPU 17, a D / A converter 19, an LD driver 8, and a pickup 7 for generating an RF signal b for generating a pseudo defect signal used for device calibration. Furthermore, this CPU 17
Is used to confirm the defect inspection ability and set the defect determination level using the generated pseudo defect signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk and a defect inspection apparatus for inspecting defects of a stamper used for manufacturing the optical disk.

[0002]

2. Description of the Related Art CD (Compact Disc) and DVD (Digita
An optical disc such as l Video Disc) includes time, address, and user information in a meandering groove called a wobble. The optical disk driver synchronizes the operation based on the information (wobble information) written in the wobble, or reads and writes information on the optical disk while seeking.

[0003] By the way, if the optical disk has scratches or dust,
As is well known, the wobble information cannot be accurately recognized by the driver, and a reading error or a writing failure in the driver may occur. To improve the reliability of optical discs by eliminating reading and writing defects due to scratches and dust,
The optical disk manufacturing process includes an inspection process for inspecting scratches and dust on an optical disk and a stamper used for manufacturing the optical disk. In the present specification, scratches and dust that affect reading and writing of an optical disk are collectively referred to as a defect, and a device used in a defect inspection process is referred to as an optical disk defect inspection device (or simply, a defect inspection device). It is assumed that.

FIG. 11 is a block diagram for explaining the configuration of a conventional general optical disk defect inspection apparatus.
Such an optical disk defect inspection apparatus is basically configured in the same manner as an optical disk driver, and further includes various feedback circuits, circuits for correcting signals, a larger memory, and the like. In the illustrated defect inspection apparatus, the optical disc A is set on the turntable 32,
The turntable 32 is rotated at a high speed of 500 to 3600 rpm by a turntable motor 33 driven by a slider 34. At the same time, the LD driver 38 controls the pickup 37 to irradiate the surface of the optical disk A with laser light having a predetermined power and beam diameter.

[0005] The laser light is reflected on the surface of the optical disk A and is converted into a push-pull signal a and an RF signal b.
Among them, the RF signal b branches off and the threshold signal generation circuit 5
0 is input to generate a threshold signal h. This threshold signal h
Is input to the defect signal generation circuit 51 together with the RF signal b not branched. FIGS. 12A and 12B are diagrams for explaining the processing performed by the defect signal generation circuit 51. FIG. 12A is a diagram for explaining a comparison between the threshold signal h and the RF signal b. (B) is a diagram showing a defect signal generated as a result. The RF signal b shown in FIG.
The peak that appears in FIG. 5 is caused by the scattering of the laser beam due to a defect on the surface of the optical disc A.

The defect signal generation circuit 51 compares the input threshold signal h with the RF signal b as shown in FIG. At this time, the RF signal b exceeding the threshold signal h
Is detected, and a binary signal shown in FIG. 12B, that is, a defect signal f is generated based on this signal. Defect signal f
Is input to the pulse width detector 46, converted into defect length data g, and input to the CPU 47. The CPU 47 detects the number and size of the defects of the optical disc A based on the defect length data g.

On the other hand, a push-pull signal a generated based on the reflected light is a BPF (bandpass filter) 39,
It is input to the CPU 47 as address information c via the binarization circuit 40 and the address decoder 41. The CPU 47
The address at which a defect exists on the optical disc A can be determined together with the address information c and the defect length data g. The data 1 on the defect thus obtained is stored in the memory 48 as needed.

In the defect inspection performed as described above,
The detection accuracy of the defect is determined by the value of the threshold signal h. In addition, the relationship between the actual defect and the defect signal f is grasped,
It is necessary to calibrate the defect inspection device so that the defect can be detected more accurately. For this reason, in the optical disk defect inspection apparatus, the optical disk for calibration called a reference plate or a stamper is used as the optical disk A in the defect inspection apparatus, and data relating to the defect is obtained to calibrate the defect inspection apparatus.

That is, a defect is previously formed on the reference plate, and an appropriate threshold value for defect inspection is set by comparing the defect with the defect signal f. Alternatively, the defect inspection apparatus is calibrated so that the defect signal f more accurately reflects the defect of the reference plate based on the difference between the data on the defect formed in advance and the defect signal f.

[0010]

However, in the optical disk inspected in the inspection step, for example, manufacturing variations may occur for each lot. Therefore, in the calibration using the reference plate, the defect inspection apparatus may not be able to be calibrated so that an appropriate defect inspection can be performed on an optical disk (optical disk under test) to be actually inspected. Furthermore, the defect inspection apparatus itself has a temporal change in an optical system such as a pickup and a drive system for driving the turntable, and the state may differ between a state in which data is acquired with the reference plate and a state in which the optical disk is inspected. Conceivable.

When a defect inspection apparatus for an optical disk is calibrated based on data acquired by a reference plate as in the prior art, even if the reference plate is initially formed with a defect as designed, it is used. In some cases, scratches and dust are formed, and the actual defect may be different from the defect at the time of formation.
In such a case, whether the difference between the defect signal f obtained by the reference plate at the time of the calibration of the defect inspection device and the predetermined defect signal to be compared is due to the state of the defect inspection device or the state of the reference plate. Therefore, there is a possibility that the defect inspection apparatus cannot be properly calibrated.

The present invention has been made in view of the above points, and a configuration for generating a more accurate pseudo defect signal for device calibration is provided in a defect inspection device itself, so that defect inspection can be performed more appropriately. It is an object of the present invention to provide an optical disk defect inspection apparatus capable of calibrating the apparatus.

[0013]

To solve the above-mentioned problems, the present invention is configured as follows. That is,
The invention according to claim 1 is a defect inspection apparatus for an optical disk or an optical disk for inspecting a defect of a stamper used for manufacturing an optical disk, wherein a pseudo defect signal generating means for generating a pseudo defect signal used for device calibration; A defect determination level setting unit configured to check a defect inspection capability and set a defect determination level by using the pseudo defect signal generated by the pseudo defect signal generating unit.

With this configuration, a function of generating a signal used for calibration can be added to the optical disk defect inspection apparatus itself. For this reason, the defect inspection apparatus can be calibrated using the optical disk on which the defect inspection is actually performed. Further, it is possible to confirm the defect inspection capability and set a defect determination level using this signal, and to maintain a constant defect inspection capability and defect determination level regardless of the state of each optical disk.

Further, the defect inspection apparatus can be calibrated by using an electrically generated pseudo defect signal. Therefore, for example, as compared with the case where calibration is performed using a reference plate or the like, it is possible to stably calibrate the defect inspection device for an optical disk irrespective of a change with time of the defect inspection device itself or the reference plate.

According to a second aspect of the present invention, the pseudo defect signal generating means emits light based on pseudo defect data set in advance to generate a pseudo defect signal, and the light emitting means comprises: An emission light adjusting means for detecting reflected light of the emitted light, and further adjusting the light emitted from the light emitting means based on the reflected light.

With this configuration, it is possible to calibrate the optical disk defect inspection apparatus so that a constant pseudo defect signal is always obtained according to the optical disk to be inspected. For this reason, the optical disk defect inspection apparatus can be calibrated so that a defect can always be detected with constant accuracy regardless of the variation of the optical disk to be inspected and the state change of the defect inspection apparatus.

According to a third aspect of the present invention, the pseudo defect signal is waveform data having a plurality of types of amplitudes or periods.

With this configuration, it is possible to always maintain a constant detection accuracy with respect to defect information obtained as signals having various amplitudes or periods.

According to a fourth aspect of the present invention, the pseudo defect signal generating means has a pulse generating means, and the pseudo defect signal is generated based on encoded data generated by the pulse generating means. Is what you do.

With this configuration, a pseudo defect signal can be generated with a relatively simple configuration.

According to a fifth aspect of the present invention, there is further provided a real data processing means for processing the real data extracted from the stamper having the defect or the optical disk to generate the pseudo defect signal. .

With such a configuration, a pseudo defect signal can be formed in accordance with the depth of the defect and the shape of the defect such as steep or gentle.

According to a sixth aspect of the present invention, the pseudo defect signal is a waveform signal having a plurality of amplitudes obtained by changing the reference to positive or negative with respect to a predetermined level, and having a constant period. It is characterized by the following.

With this configuration, it is possible to limit the range of the amplitude of a defect signal that can be detected as a defect signal, that is, to set a detection threshold. Accordingly, it is possible to calibrate the optical disk defect inspection apparatus so that the defect detection accuracy is set to be constant regardless of the variation of the optical disk to be inspected and the state change of the defect inspection apparatus.

According to a seventh aspect of the present invention, the pseudo defect signal is a digital waveform signal having a constant amplitude and a variable period.

With this configuration, the optical disk defect inspection apparatus is calibrated so that the period of the defect signal can be obtained with a constant measurement accuracy regardless of the variation of the optical disk to be inspected or the state change of the defect inspection apparatus. be able to.

According to an eighth aspect of the present invention, the pseudo defect signal is a sine wave having a constant amplitude and a variable period.

With this configuration, the defect of the optical disk can be obtained with a constant measurement accuracy regardless of the variation of the optical disk to be inspected, the change in the state of the defect inspection apparatus, and the shape of the pseudo defect signal. The inspection device can be calibrated.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 and 2 of the present invention will be described below. (Embodiment 1) The optical disk defect inspection apparatus according to Embodiment 1 of the present invention is an optical disk defect inspection apparatus for inspecting defects of an optical disk or a stamper used for manufacturing an optical disk. In the first and second embodiments of the present invention, the optical disk defect inspection apparatus is
An example applied to a defect inspection of an optical disk will be described.

An optical disk defect inspection apparatus according to the first embodiment uses a pseudo defect signal generating means for generating a pseudo defect signal used for device calibration and a pseudo defect signal generated by the pseudo defect signal generating means. Defect determination level setting means for confirming the capability and setting the defect determination level. Then, the pseudo defect signal generating means detects light reflected by the light emitted by the light emitting means, and a light emitting means for emitting light based on pseudo defect data set in advance to generate a pseudo defect signal, An emission light adjusting means for adjusting the light emitted from the light emitting means based on the reflected light is further provided.

FIG. 1 is a block diagram for explaining such an optical disk defect inspection apparatus according to the first embodiment. The illustrated configuration includes an LD driver 8, a pickup 7 driven by the LD driver 8 to irradiate the optical disc 1 with laser light, and laser light emitted by the pickup 7 generated from reflected light reflected on the surface of the optical disc 1. A tracking control unit 24 for processing a push-pull signal a, a BPF 9, a binarization circuit 10, an address decoder 11, a buffer amplifier 12 for processing an RF signal b,
A threshold signal generation circuit 20 including an LPF (low pass filter) 13 and an amplifier 14, a defect signal generation circuit 25, a pulse width detection circuit 16, and a CPU 1 for controlling the above configuration
7 and a memory 18 for storing the result of operation by the CPU 17 as necessary, or for storing data and programs used in the processing of the CPU 17.

Further, the CPU 17 of the first embodiment includes:
A pulse generator 26 as a pulse generating means is built in. The RF signal b serving as a pseudo defect signal is generated based on the encoded data generated by the pulse generator 26, as described later.

Further, the configuration shown in FIG.
(Turntable) A slider control unit 6 and a slider motor 5 are provided. The TT slider control unit 6 includes a CPU 17
The TT motor 3 that rotates the turntable 2 on which the optical disc 1 is placed is rotated in accordance with this control. Further, the TT slider control unit 6
Are configured to drive the slider 4 by controlling the slider motor 5. Note that the pickup 7 of the first embodiment is provided with a laser emission / tracking / focusing /
It is assumed that a quadrant diode is provided.

The optical disk defect inspection apparatus according to the first embodiment outputs the light quantity data d based on the pulse generated by the pulse generator 26, and D / A converts this signal to generate a light quantity control signal e. It has a D / A converter 19 for outputting. The LD driver 8 controls the laser beam emitted from the pickup 7 based on the light amount control signal e. By this control, the laser light irradiated by the pickup 7 and its reflected light change, and the RF signal b also changes.

In the above configuration, the CPU 17 for generating the RF signal b, the D / A converter 19, the LD driver 8, and the pickup 7 constitute the pseudo defect signal generating means of the first embodiment. The CPU 17 functions as a defect determination level setting unit that uses the generated pseudo defect signal to check the defect inspection capability and set a defect determination level. In the configuration serving as the pseudo defect signal generating means, the pickup 7 serves as the light emitting means, and the CPU 17, the LD driver 8, and the D / A converter 19 serve as the emitting light adjusting means.

Further, for example, the memory 18 of the CPU 17
Stores pseudo defect data set in advance to generate a pseudo defect signal. The pseudo defect signal is waveform data having a plurality of types of amplitudes or periods, and the pseudo defect data according to the present invention refers to data for generating such a pseudo defect signal. Embodiment 1
Here, it is assumed that a pseudo defect signal is generated by generating a pulse in the pulse generator 26 based on the pseudo defect data. The CPU 17 has three types of the pseudo defect data, and can generate three types of pseudo defect signals corresponding to each of the three types. The details of the pseudo defect signal will be described later.

The above configuration operates as follows to calibrate the optical disk defect inspection apparatus. That is, the CPU 17
Outputs the TT slider control information k to the TT slider control unit 6 and instructs the TT slider control unit 6 to rotate the TT motor 3 and the slider motor 5. The TT slider control unit 6 outputs a TT control signal i to the TT motor 3 and a slider control signal j to the slider motor 5 according to the instruction. T
The T motor 3 rotates the turntable 2 at 500 to 3600 rpm according to the TT control signal i. The slider motor 5 moves the slider 4 relatively to the optical disc 1.

Further, the CPU 17 outputs light amount data d at predetermined time intervals based on the pseudo defect data. The light amount data d is input to the D / A converter 19, where the D / A
The signal is subjected to A conversion and becomes a light amount control signal e. Light intensity control signal e
Is data that fluctuates according to the pseudo defect data,
The signal is input to the LD driver 8 to control the driving of the pickup 7 by the LD driver 8.

As a result, the pickup 7 irradiates a laser beam having a variation corresponding to the pseudo defect data toward the surface of the optical disk 1 to be actually inspected in the defect inspection step, and is reflected. If there is no defect or the like that scatters the laser light on the optical disk 1, a change in the irradiated laser light is reflected on the reflected light. Therefore, this variation is also reflected in the RF signal b which is a pseudo defect signal generated based on the reflected light.

Hereinafter, the light amount control signal e and the pickup 7
The relationship between the laser light emitted from the device and the RF signal b, which is a pseudo defect signal, will be described with reference to FIGS. FIG.
Light amount control signal e of Embodiment 1, irradiated laser light,
FIGS. 3A and 3B show the relationship between the RF signals b. FIG. 3A shows the light amount control signal e, FIG. 3B shows the laser light, and FIG. 3C shows the RF signal b. FIG. 2 is a diagram showing a relationship between a conventional light amount control signal e, an irradiated laser beam, and an RF signal b for comparison. FIG. 2A shows a light amount control signal e,
(B) shows the laser beam, and (c) shows the RF signal b. In FIGS. 2 and 3 (a) and (c), the vertical axis indicates voltage, and the horizontal axis indicates time. In FIGS. 2 and 3B, the vertical axis indicates the light amount, and the horizontal axis indicates the time.

In the conventional example shown in FIG. 2, when calibrating an optical disk defect inspection apparatus, first, an optical disk serving as a reference plate as the optical disk A is set on the turntable 32. Subsequently, a constant voltage is supplied from a voltage source (not shown) to the LD driver 38 as a light amount control signal e (FIG. 2A). The LD driver 38 controlled by such a light amount control signal e drives the pickup 37 so that the light amount shown in FIG. 2B irradiates a constant laser beam regardless of time. At this time, the laser light applied to the defect of the optical disc A is scattered, and the intensity of the reflected light fluctuates. As a result, a voltage fluctuation as shown in FIG. 2C also occurs in the RF signal b.

In a conventional optical disk defect inspection apparatus, R
A defect of the optical disc A is detected based on the F signal b, and defect length data g is further obtained. Then, the number of detected defects (density) is compared with the number of defects formed on the reference plate (density), and the difference between the obtained defect length data and the length of the defects formed on the reference plate is examined. Has been calibrated so that the defect inspection apparatus can detect defects more accurately.

On the other hand, in the optical disk defect inspection apparatus according to the first embodiment, calibration is performed on all optical disks to be inspected for defects in the optical disk defect inspection apparatus process. That is, the CPU 17 sets the light amount data d based on the pseudo defect data on each of the optical disks to be inspected.
Is output. The light quantity data d is converted by the D / A converter 19 into, for example, a light quantity control signal e shown in FIG. The LD driver 8 controlled by the light amount control signal e in FIG. 3A drives the pickup 7 so as to emit a laser beam having a light amount fluctuation reflecting the light amount control signal e (FIG. 3B). ).

R generated based on the reflected light of the laser light
A peak due to the voltage fluctuation appears in the F signal b as shown in FIG. This peak reflects the pseudo defect data on which the light quantity data d was based, and the RF signal b having such a peak was scattered on the surface of the optical disk having the defect represented by the pseudo defect data. R based on reflected light
This is similar to the F signal b. Therefore, the RF signal b
Becomes a pseudo defect signal.

The RF signal b generated as described above
Is branched after passing through the buffer amplifier 12, one of which is input to the threshold signal generation circuit 20, and the other is input to the defect signal generation circuit 25. The RF signal b input to the threshold signal generation circuit 20 is converted into a threshold signal h by the LPF 13 and the amplifier 14 and input to the defect signal generation circuit 25. The defect signal generation circuit 25 detects a defect by comparing the signal input here as the RF signal b with the threshold signal h. This detection result is input to the pulse width detection circuit 16 as a defect signal f, and is input to the CPU 17 as defect length data g.

The CPU 17 further determines whether or not the defect signal f is a predetermined signal based on the defect length data g. When the defect signal f is different from the predetermined signal, if the difference is equal to or more than the allowable value, the light amount data d and the light amount control signal e are corrected so that the difference between the two is within the allowable range. Controls the LD driver 8. For this reason, the laser beam emitted from the pickup 7 is corrected so as to always obtain a constant defect detection accuracy irrespective of the variation of the optical disk 1 or the temporal change of the state of the defect inspection apparatus. Can be calibrated.

Further, the pseudo defect signal used for such calibration is a signal created only by the processing performed by software as described above. For this reason, in the first embodiment, a calibration signal can be stably obtained irrespective of factors such as the processing accuracy of the optical disc and the stamper, and furthermore, damage over time. Therefore, in the first embodiment, the optical disk defect inspection apparatus can be calibrated with higher accuracy.

In the optical disk defect inspection apparatus according to the first embodiment, the push-pull signal a is generated from the light reflected on the surface of the optical disk 1, branched, and output to the tracking control unit 24 and the BPF 9. I have. The push-pull signal “a” output to the tracking control unit 24 is fed back to the pickup 7. Further, the push-pull signal a output to the BPF 9 is further input to the binarization circuit 10 and the address decoder 11, converted into address information c, and input to the CPU 17. By inputting such address information c together with the defect length data g, the CPU 17 can specify not only the size of the defect but also the position of the defect.

Next, three types of pseudo defect signals (hereinafter, referred to as pseudo defect signal 1, pseudo defect signal 2, and pseudo defect signal 3) used in the optical disk defect inspection apparatus according to the first embodiment will be described. (Pseudo Defect Signal 1) FIG. 4 is a diagram for explaining the pseudo defect signal 1, and FIG. 4A is a diagram showing an RF signal b generated as the pseudo defect signal 1 and a threshold signal h. ,
(B) is a diagram showing a defect signal f generated from the RF signal b and the threshold signal h shown in (a).

The pseudo defect signal 1 has a plurality of amplitudes obtained by changing the reference to positive or negative with respect to a predetermined level.
Moreover, it is a waveform signal having a fixed cycle. The illustrated pseudo defect signal 1 (RF signal b) has a constant period and
Of these, the time widths of the high output H and the low output L are also constant. The peak toward the low output side indicates the scattering of the laser beam due to the defect, and the defect length data g is determined based on the low output time width. Pseudo defect signal 1
In the example, the low output time width is set to be half of the high output time width, and when the high output time width is set as a reference T, the low output time width is expressed as 0.5T.

In the first embodiment, the pseudo defect signal 1
Was changed in the direction of low output (negative direction) in steps of 2.5% with respect to the predetermined amplitude, and was set so as to be in the range of 10% to 40% of the reference amplitude.
In the pseudo defect signal 1 shown in FIG. 4A showing a part thereof, the amplitude of the peak at the left end in the figure is 10% of the amplitude of the reference signal value, and the peak at the right end has an amplitude of 25%. Have.

The defect signal f is generated by comparing the above-described pseudo defect signal 1 with the threshold signal h. That is, only the signal exceeding the threshold signal h (below in FIG. 4) among the peaks included in the pseudo defect signal 1 is detected, and has the same time width and constant value S as the low output of this signal. A defect signal is generated as a digital signal. According to such processing, the detection accuracy of the defect signal f is determined by the value of the threshold signal h.

The determination of the threshold signal h is performed by an operator who calibrates the optical disk defect inspection apparatus. At this time, the operator selects a desired defect detection accuracy and sets the threshold signal h to a value corresponding to the accuracy. However, the set value may be different from the value actually compared with the pseudo defect signal as the threshold signal h due to the configuration of the apparatus. For this reason, the operator may, for example, set a predetermined value of 15
When it is desired to detect a signal having an amplitude of not less than% as a defect signal, the threshold signal h is set to a value such that the third signal from the left end of the signal shown in FIG. 4B is detected. According to the above processing, the accuracy of detecting a signal having an amplitude of 15% ± 2.5% of a predetermined value as a defect is guaranteed.

Next, a process of performing calibration using the pseudo defect signal 1 in the optical disk defect inspection apparatus according to the first embodiment will be described with reference to a flowchart shown in FIG. In the flowchart of FIG. 5, when the processing is started, first, the CPU 17 outputs the light amount data d (S1). The light quantity data d in this flowchart is based on the pseudo defect data for generating the pseudo defect signal 1 described above. In the optical disk defect inspection apparatus according to the first embodiment, the D / A converter 19 converts this to generate a light quantity control signal e,
Output to the D driver 8 (S2). Then, a laser beam based on the light quantity control signal e is emitted from the pickup 7 toward the optical disc 1 (S3).

The emitted laser light is reflected on the surface of the optical disk 1 to generate reflected light. An RF signal b serving as a pseudo defect signal is generated from the reflected light (S4). This pseudo defect signal is the pseudo defect signal 1 shown in FIG.
Becomes The generated pseudo defect signal is compared with a threshold signal h and converted into a defect signal f (S5). Defect signal f
Is further analyzed (S6), and the value of the threshold signal h is obtained so that the desired detection accuracy is obtained based on the instruction of the operator.
That is, it is used to determine the threshold (S7).

According to the above-described processing, it is possible to set a threshold value that can always obtain a constant defect detection accuracy irrespective of the variation of the optical disk and the change over time of the defect inspection apparatus.
Further, since the threshold value can be determined based on the electrically generated pseudo defect signal, it is possible to accurately specify the threshold value at which a desired detection accuracy is obtained. Further, by counting the generated defect signals, the amplitude of the pseudo defect signal actually detected can be determined. Therefore, due to the configuration of the device,
Even when the set threshold value is different from the actually used threshold value, it is possible to set a threshold value at which substantially desired detection accuracy is obtained.

(Pseudo Defect Signal 2) FIG. 6 is a diagram for explaining the pseudo defect signal 2. FIG. 6 (a) shows the RF signal b generated as the pseudo defect signal 2 and the threshold signal h. (B) is a diagram showing a defect signal f generated from the RF signal b and the threshold signal h shown in (a).

The pseudo defect signal 2 is a digital waveform signal having a constant amplitude and a variable period. That is, the illustrated pseudo defect signal 2 (RF signal b) is 50% of the amplitude (the value of the high output H and the value of the low output L) as a reference.
The peak toward the low output side shows the scattering of the laser beam due to the defect. In the pseudo defect signal 2, the high output time width is set to the reference T, and the low output time width is set to 0.6.
It was set to be changed from T to 3T in increments of 0.2T. The pseudo defect signal 2 in FIG. 6A shows a part of this.

The defect signal f shown in FIG.
It is generated by comparing the pseudo defect signal 2 shown in (a) with the threshold signal h. That is, only the signal that exceeds the threshold signal h (below in FIG. 6) among the peaks included in the pseudo defect signal 2 is detected, and has the same time width and constant value S as the low output of this signal. The defect signal f is generated as a digital signal. The defect length data g is determined based on the low output time width.

In the calibration of the optical disk defect inspection apparatus using the pseudo defect signal 2, the obtained defect length data g and the originally obtained defect length data are compared, and if the difference between the two is greater than an allowable value. Then, the light amount data d and the light amount control signal e are corrected so as to reduce the difference. According to such a process, the optical disk defect inspection apparatus according to the first embodiment always inspects a defect in a state where a predetermined defect detection accuracy can be obtained regardless of variations in the optical disk or changes in the defect inspection apparatus. Can be. In the example of the pseudo defect signal 2 shown in FIG. 6A, the detection accuracy of 0.2T can be guaranteed for the defect length regardless of the value of the defect length.

(Pseudo defect signal 3) RF signal b generated by a defect existing on an actual optical disk
Is determined by a combination of various factors such as depth, width, reflectance, etc., in addition to scattering intensity and defect length. Therefore, in the first embodiment, the defect inspection apparatus for the optical disk is calibrated using the pseudo defect signal 3, and the responsiveness of the RF signal b is also taken into consideration. FIG. 7 is a diagram for explaining such a pseudo defect signal 3. FIG. 7A is a diagram showing an RF signal b and a threshold signal h generated as the pseudo defect signal 3, and FIG. ) Is the RF signal b shown in FIG.
FIG. 5 is a diagram showing a defect signal f generated from a threshold signal h and a threshold signal h.

The pseudo defect signal 3 is a sine wave having a constant amplitude and a variable period. That is, the illustrated pseudo defect signal 3 (RF signal b) has a constant amplitude (high output H and low output L values), and the peak toward the low output side represents the scattering of laser light due to the defect. I have. Such a pseudo-defect signal 3 is used to constantly maintain a change in the defect signal due to the falling edge or shape of the RF signal b irrespective of variations in the optical disk and the state of the defect inspection apparatus. The change in the defect signal due to the falling edge or the shape of the RF signal b means that, for example, an accurate time width is guaranteed for the peak of the RF signal b whose falling edge is relatively steep, but relatively slow. For a changing shallow peak, the time width tends to be shorter depending on how the threshold value is determined.

Next, FIG. 8 is a flowchart showing a process of performing calibration using the pseudo defect signal 2 or the pseudo defect signal 3 in the optical disk defect inspection apparatus according to the first embodiment.
explain. In the flowchart of FIG. 8, when the processing is started, first, the CPU 17 outputs the light amount data d (S1).
1). Note that the light quantity data d in the flowchart is based on the pseudo defect data for generating the pseudo defect signal 2 or the pseudo defect signal 3. In the optical disk defect inspection apparatus according to the first embodiment, the D / A converter 19 converts this to generate a light amount control signal e and outputs it to the LD driver 8 (S12). Then, a laser beam based on the light quantity control signal e is emitted from the pickup 7 toward the optical disc 1 (S13).

The emitted laser light is reflected on the surface of the optical disk 1 to generate reflected light. An RF signal b serving as a pseudo defect signal is generated from the reflected light (S14). In addition,
This pseudo defect signal becomes the pseudo defect signal 2 shown in FIG. 6A or the pseudo defect signal 3 shown in FIG. 7A. The generated pseudo defect signal is compared with a threshold signal h and converted into a defect signal f (S15). The defect signal f is further analyzed (S16), and the light amount data d and the light amount control signal e are corrected based on the analysis result (S17).

Embodiment 2 Next, Embodiment 2 of the optical disk defect inspection apparatus of the present invention will be described. The optical disk defect inspection apparatus according to the second embodiment of the present invention is configured to further include actual data processing means for processing actual data extracted from the optical disk inspected in the defect inspection step to generate a pseudo defect signal. It is a thing.

FIG. 9 is a block diagram for explaining the configuration of the optical disk defect inspection apparatus according to the second embodiment. However, the configuration shown in FIG. 9 includes a portion configured similarly to the configuration of FIG. 1 described in the first embodiment. Therefore, in the second embodiment, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be partially omitted.

The optical disk defect inspection apparatus according to the second embodiment shown in FIG. 9 has a CPU 1 serving as a pseudo defect signal generating means and a defect determination level setting means as in the configuration of FIG.
7. D / A converter 19 serving as pseudo defect signal generating means, L
It has a D driver 8 and a pickup 7. further,
The optical disk defect inspection apparatus according to the second embodiment includes a tracking control unit 24 for processing the push-pull signal a,
A BPF 9, a binarization circuit 10, an address decoder 11,
Buffer amplifier 12, LP for processing RF signal b
Threshold signal generation circuit 2 including F13 and amplifier 14
0, a defect signal generation circuit 25, and a pulse width detection circuit 16.

Further, the CPU 17 is connected to the memory 18 and the TT slider control unit 6, and the TT slider control unit 6 controls the slider motor 5. The slider motor 5 is configured to drive the slider 4, and the slider 4 is connected to the TT motor 3 that rotates the turntable 2 on which the optical disk 1 is mounted and rotates.

Further, the optical disk defect inspection apparatus according to the second embodiment has an actual data processing section 27 comprising an amplifier 21, an A / D converter 22, and a buffer memory 23.
The optical disk defect inspection apparatus according to the second embodiment is configured to be able to analyze more complicated and diverse defects in detail in addition to the effects obtained in the first embodiment. Such an optical disk defect inspection apparatus is effective when analyzing a defect at a specific address on an optical disk in detail.

FIG. 9 shows a second embodiment of the present invention.
An optical disk defect inspection apparatus will be described. In the second embodiment, the optical disk 100 to be inspected is set on the turntable 2 and rotated. Then, the optical disk 100 is irradiated with a laser beam having a constant light intensity by the pickup 7, and the push-pull signals a and R
Generate the F signal b. The optical disk defect inspection apparatus according to the second embodiment recognizes a specific address of the optical disk 100 to be analyzed from the push-pull signal a and takes in the RF signal b of this address.

More specifically, the push-pull signal a branches into the address information c and the fetch start signal o in the address decoder 11. An RF signal b based on the light reflected by the optical disc 100 is input to the amplifier 21 via the buffer amplifier 12, where it is amplified and has the same voltage level as the light quantity control signal e. This RF signal b further includes A
The digital signal is converted into a digital signal by the A / D converter 22 and sequentially stored in the buffer memory 23.

At this time, the A / D converter 22 starts to fetch the RF signal b when the fetch start signal o is input from the address decoder 11. By this capture, the R stored in the buffer memory 23 as voltage data
The F signal b is output to the CPU 17 as a defect pattern signal m at every measurement of the optical disc 100. CPU 17
The defect pattern signal m is inputted, temporarily stored in the memory 18, and output to the D / A converter 19 while changing its amplitude or cycle at a predetermined timing, whereby the RF obtained at a specific address of the optical disc 100 is obtained.
A pseudo defect signal similar to the signal b can be generated.

FIG. 1 is a flowchart showing a process of performing calibration by the optical disk defect inspection apparatus according to the second embodiment.
0 and described. In the flowchart of FIG. 10, when the processing is started, first, the CPU 17 outputs the light amount data d (S21). The light quantity data d in the flowchart is data for controlling light of a constant intensity to be emitted from the pickup 7. In the optical disk defect inspection apparatus according to the second embodiment, the D / A converter 19 converts this to generate a light amount control signal e, which is output to the LD driver 8 to emit laser light from the pickup 7 (S22). .
Then, the RF signal b generated based on the reflected light is processed (S23), and it is determined whether or not the capture start signal o generated based on the push-pull signal a has been output (S24).

If the result of determination in step S24 is that the capture start signal o has not been output (S24: N
o) Wait until output. If the signal is output (S24: Yes), the capture of the RF signal b is started to create the defect pattern signal m (S25). The created defect pattern signal m is stored in the memory 18 (S26).

After the above processing, the defect pattern signal m stored in the memory 18 is read out if necessary, and
The light quantity data d is output from U17 to control the LD driver 8, and finally a pseudo defect signal unique to an address on the optical disc 100 is generated.

[0077]

The present invention described above has the following effects. That is, according to the first aspect of the present invention, the defect inspection apparatus can be calibrated using the optical disk on which the defect inspection is actually performed. It can be kept stable regardless of it. Further, the defect inspection apparatus can be configured such that a defect can be detected more accurately according to the characteristics of various types of optical discs.

Further, the defect inspection apparatus can be calibrated by using an electrically generated pseudo defect signal. Therefore, it is possible to calibrate the optical disk defect inspection apparatus based on a more accurate and stable defect signal. it can. According to such an optical disk defect inspection apparatus, the reliability of the defect inspection apparatus can be further improved.

According to the second aspect of the present invention, it is possible to calibrate an optical disk defect inspection apparatus so that a defect can always be detected with a constant accuracy regardless of variations in the optical disk to be inspected and changes in the state of the defect inspection apparatus. According to such an optical disk defect inspection apparatus, the reliability of the defect inspection apparatus can be further improved.

According to the third aspect of the present invention, a constant detection accuracy can always be maintained even for information relating to a defect obtained as a signal having various amplitudes or periods, and the reliability of the defect inspection apparatus can be further improved. .

According to the fourth aspect of the present invention, a pseudo defect signal can be generated with a relatively simple configuration, and furthermore, the configuration of a defect inspection apparatus for an optical disk can be simplified and downsized, and a pseudo defect signal can be generated. It is also possible to suppress an increase in cost due to the provision of.

According to the fifth aspect of the present invention, a pseudo defect signal can be formed in accordance with the defect depth or the shape of the defect such as steep or gentle, and a defect inspection can be performed in accordance with the actual defect state. Therefore, the reliability of the defect inspection device can be further improved.

According to the sixth aspect of the present invention, the optical disk defect inspection apparatus can be calibrated so that the defect detection accuracy is set to be constant regardless of the variation of the optical disk to be inspected or the state change of the defect inspection apparatus. . Therefore, the reliability of the defect inspection device can be further improved.

According to a seventh aspect of the present invention, the defect inspection apparatus for an optical disk is calibrated so that the cycle of the defect signal can be obtained with a constant measurement accuracy irrespective of the variation of the optical disk to be inspected or a change in the state of the defect inspection apparatus. be able to. For this reason, it becomes possible to accurately acquire data particularly on the defect length, and the reliability of the defect inspection apparatus can be further improved.

According to the present invention, the defect of the optical disk can be obtained with a constant measurement accuracy irrespective of the variation of the optical disk to be inspected, a change in the state of the defect inspection apparatus, and the shape of the pseudo defect signal. The inspection device can be calibrated. Therefore, the reliability of the defect inspection device can be further improved. The present invention provides a defect inspection apparatus for an optical disk capable of providing a configuration for generating a more accurate pseudo defect signal for device calibration in the defect inspection apparatus itself and calibrating the apparatus so that the defect inspection can be performed more appropriately. It can be said that it can do.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an optical disk defect inspection apparatus according to a first embodiment of the present invention.

FIG. 2 shows a conventional light amount control signal e, an irradiated laser beam,
FIG. 4 is a diagram illustrating a relationship of an RF signal b.

FIG. 3 is a diagram showing a relationship among a light amount control signal e, an irradiated laser beam, and an RF signal b according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a pseudo defect signal 1 according to the first embodiment of the present invention.

FIG. 5 is a flowchart illustrating a process performed by the optical disk defect inspection apparatus according to the first embodiment;

FIG. 6 is a diagram for explaining a pseudo defect signal 2 according to the first embodiment of the present invention.

FIG. 7 is a diagram for explaining a pseudo defect signal 3 according to the first embodiment of the present invention.

FIG. 8 is another flowchart for explaining a process performed by the optical disk defect inspection apparatus according to the first embodiment;

FIG. 9 is a block diagram illustrating an optical disk defect inspection apparatus according to a second embodiment of the present invention.

FIG. 10 is another flowchart for explaining processing performed by the optical disk defect inspection apparatus according to the second embodiment;

FIG. 11 is a block diagram for explaining a conventional general optical disk defect inspection apparatus.

FIG. 12 is a diagram for explaining processing performed by the defect signal generation circuit shown in FIG. 11;

[Explanation of symbols]

 1, 100 optical disk 2 turntable 3, 33 TT motor 4, 34 slider 5 slider motor 6 slider control unit 7, 37 pickup 8, 38 driver 10, 40 binarization circuit 11, 41 address decoder 12 buffer amplifier 14 amplifier 16, 46 pulse width detection circuit 18, 48 memory 19 D / A converter 20, 50 threshold signal generation circuit 21 amplifier 22 converter 23 buffer memory 24 tracking control unit 25 defect signal generation circuit 26 pulse generator 27 actual data processing unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 20/18 572 G11B 20/18 572F

Claims (8)

[Claims] 1. A defect inspection apparatus for an optical disk or an optical disk for inspecting a defect of a stamper used for manufacturing an optical disk, comprising: a pseudo defect signal generating means for generating a pseudo defect signal used for device calibration; An optical disk defect inspection device, comprising: a defect determination level setting unit configured to check a defect inspection capability and set a defect determination level using a pseudo defect signal generated by a signal generation unit. 2. A light emitting means for emitting light based on pseudo defect data set in advance to generate a pseudo defect signal, and a reflected light of light emitted by the light emitting means. 2. An optical disk defect inspection apparatus according to claim 1, further comprising: an emission light adjusting means for detecting the light emission and adjusting the light emitted from the light emission means based on the reflected light. 3. The optical disk defect inspection apparatus according to claim 1, wherein the pseudo defect signal is waveform data having a plurality of types of amplitudes or periods. 4. The pseudo-defect signal generating means includes pulse generating means, and the pseudo-defect signal is generated based on encoded data generated by the pulse generating means. An optical disk defect inspection device according to any one of the above. 5. The apparatus according to claim 1, further comprising actual data processing means for processing the actual data extracted from the stamper having a defect or the optical disk to generate the pseudo defect signal. An optical disk defect inspection apparatus according to any one of the above. 6. The pseudo-defect signal is a waveform signal having a plurality of amplitudes obtained by changing the reference to positive or negative with respect to a predetermined level and having a constant period. Item 6. An optical disk defect inspection device according to any one of Items 1 to 5. 7. The optical disk defect inspection apparatus according to claim 1, wherein the pseudo defect signal is a digital waveform signal having a constant amplitude and a variable period. . 8. The optical disk defect inspection apparatus according to claim 1, wherein the pseudo defect signal is a sine wave having a constant amplitude and a variable period.