JP2768798B2 - Optical disk inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk inspection apparatus for measuring and inspecting an optical disk, and more particularly to an optical disk inspection apparatus suitable for grasping a signal recording state on an optical disk.

2. Description of the Related Art As a conventional apparatus for inspecting an optical disc, for example, as described in Japanese Patent Application Laid-Open No. 59-183310, a minute height which becomes a defect of the optical disc by using coherent light and an optical system is disclosed. Or, those that detect the shape and position of the depth are generally known.

[Problems to be Solved by the Invention] However, the conventional apparatus as described above has a configuration separate from a signal reproducing apparatus for reproducing a recording signal on an optical disk, and is not associated with the signal reproducing apparatus. Reproduction signals could not be detected and observed in correspondence. For this reason, in the conventional apparatus, it was not possible to specify how the detected abnormal shape or the like actually affects the reproduced signal.

On the other hand, it is useful not only for quality control of optical discs and optical disc recording devices, but also for improvement and development research of optical discs and the like, and there is a great demand for measuring such detection signals and reproduction signals in correspondence. Conceivable.

As shown in Table 1, methods for measuring an optical disc include a method using a microscope, a laser light interferometry, and a method for measuring a servo error signal using an oscilloscope. . The parentheses in Table 1 indicate whether measurement is possible regardless of the relationship with the reproduced signal.

In view of the above, an object of the present invention is to provide an optical disk inspection apparatus that can detect a detection result relating to a track shape, a missing bit and the like and a reproduction signal in a corresponding manner, and can specify a reproduction signal at an abnormal portion. It is in.

Means for Solving the Problems In order to achieve the above object, the present invention provides an optical system that irradiates a rotating optical disc with a light beam at a predetermined speed and receives reflected light from the optical disc, A sensor unit for detecting a moving position of a system pickup in a disk radial direction and a rotating position of the optical disk, a demodulating means for demodulating a reproduced signal from a signal obtained from the optical system, and a first storage for storing the reproduced signal Means, second storage means for storing at least one kind of detection signal obtained from the optical system, and position data obtained from the sensor section, display means for displaying the reproduced signal as an image, The reproduction signal stored in the storage means is sequentially read and displayed on the display means, and at the same time, the detection signal and the position stored in the second storage means are synchronized with the reproduction signal. Arithmetic control means for reading data and performing a predetermined inspection process.

Further, as one mode of the present invention, a first instruction means for stopping the video being displayed on the display means in the middle, and a defective part in a still image of the display means which is stopped by the instruction of the first instruction means Second instruction means for instructing a position of the reproduction signal, wherein the arithmetic control means extracts the detection signal and the position data corresponding to the defective portion in the reproduction signal designated by the second instruction means. Then, the information is converted into graphic information indicating the degree of the defect, and the information is displayed on the second display means.

Further, as another embodiment of the present invention, the apparatus further comprises reference value setting means for presetting a reference value for disk inspection with respect to one or more kinds of the detection signals, wherein the arithmetic control means controls a level of the detected detection signal. The pass / fail judgment is made by comparing with the reference value.

[Operation] In the present invention, the signals recorded on the optical disk are reproduced into the original video / audio signals, and at the same time, the detection signals (tracking error signal, focus error signal, tilt error signal, RF signal) obtained from the sensor section are obtained. ) Together with the position signal (r, θ) indicating the position of the pickup, temporarily store those signals, and then read out the reproduction (video) signal and the detection signal / position signal while making them correspond on the same time axis. The reproduced video is displayed on the monitor means, and various inspection processes relating to the optical disk are executed. Therefore, according to the present invention, it is possible to correlate the detection signal obtained by measuring the disk surface or the like with the reproduction signal, and to easily recognize the relationship between the defective portion of the disk and the defective portion on the reproduction signal. Therefore, according to the present invention, it is easy to measure the defective portion of the optical disk, and it is possible to measure the shape of the defective portion of the recording signal on the disk surface. As a result, the number of defective disks can be reduced.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an optical disk inspection apparatus according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical disk to be measured, 2 denotes an optical system, and 3 denotes a light-receiving detecting device that receives a light beam incident on the optical disk 1 via the optical system 2 and receives the reflected light. 4 is various detection data from the detection device 3 for light reception
ERR, RF, r and encoder 14 of optical disk rotation motor 13
Is a data storage device for temporarily storing the rotation angle data θ from the RAM, for example, a RAM (random access memory) or the like. Reference numeral 5 denotes a demodulator for demodulating a recording signal reproduced by the light receiving detection device 3, and an image signal (reproduction signal) demodulated by the demodulator 5 is displayed on a monitor display device (hereinafter, referred to as a CRT) 11. And stored in the frame memory 6. Reference numeral 7 denotes a personal computer (hereinafter abbreviated as a personal computer) as arithmetic control means for executing various inspections based on the detected data and the reproduced signal, and the arithmetic result is displayed on a second display device (CRT) 12. Is done. Reference numeral 8 denotes an operation key for giving a start instruction to the personal computer 7 and the frame memory 6.

2 to 7 show a detailed configuration example of the optical system 2 and the light receiving detection device 3 of FIG.

First, FIG. 2 shows the configuration of the optical system 2 of the pickup. The linearly polarized light (divergent light) of about 3 mW emitted from the laser diode 21 is divided by the diffraction grating 22 into three lights. The two lights on both sides are used for tracking detection,
The central light is used for focus detection and recording signals. After passing through the polarizing beam splitter (PBS) 23, 3
The divergent light of the book becomes parallel light by the collimating lens 24, and rises in the direction perpendicular to the disk by the prism mirror 25.

This light is converted into circularly polarized light by a quarter-wave plate 36, and the objective lens 27 incorporated in the two-dimensional actuator moves in the radial direction and the vertical direction of the disk 1, thereby forming a fine spot on the pit surface of the disk 1. Converged to connect 19. The light that has been diffracted by the pits in the disk 1 and that has been totally reflected by the reflecting surface and whose circularly polarized light has its rotation direction reversed is returned to the objective lens 27, follows the optical path in reverse, and passes through the quarter-wave plate 26 again. As a result, the light is converted into linearly polarized light orthogonal to the incident light, so that the light is reflected by the polarization beam splitter 23 without being transmitted, and reaches the photodiode (detector) 29. The cylindrical lens 28 is necessary for detecting a focus control signal.

FIG. 3 shows the principle of focus control signal detection. Third
As shown in FIG. 3A, the light reflected on the surface of the disk 1 and reflected by the polarization beam splitter 23 passes through the cylindrical lens 28 and strikes the light receiving surface of the photodiode 29. The disc 1 is too close to the focal position of the objective lens 27,
When it is too far away, the light receiving surface is hit by elliptical light as shown in FIG. 3 (B), and a focus error voltage as shown in FIG. 3 (C) can be detected.

On the other hand, the ± 1st-order lights split by the diffraction grating 22 (two of the two lights on the both sides of the three split lights) are connected to spots slightly separated on the same track by the objective lens 27 as shown in FIG. The reflected light of each is detected by a photodiode 29 for signal detection.
At both sides (A and C), and the difference between the track and the spot is detected from the difference.

FIG. 5 shows the change in the light hitting the photodiode 29.
FM, focus error, tracking error, and 4D
5 shows a signal pickup circuit for extracting a sum signal. The outputs of the four divided photodiodes B1 to B4 are amplified by the FM amplifier 31 through the capacitors via the capacitors. This signal is a video / audio FM signal with frequency components up to about 14 MHz. In this example, this signal is a pit presence / absence signal (RF signal)
Also used as

In the focus error detection, (B1 + B3)-(B2 + B4) is extracted by a differential amplifier for the low frequency components of B1 to B4.
The objective lens driving servo operates so that this signal becomes zero. In this example, this focus error signal is extracted as a detection signal.

The 4D sum detection is a sum of low frequency components B1 to B4, and the voltage increases when light is focused on the disk surface. This is used as a signal for turning on the focus servo loop.

In the tracking error detection, the output of the photodiodes A and C is taken as (AC) and taken out by a differential amplifier. The objective driving servo operates so that this signal becomes zero.
In this example, this tracking error signal is extracted as a detection signal.

FIG. 6A shows a laser driving circuit. As shown in FIG. 6 (B), the laser diode 21 is housed in one case together with the monitoring photodiode 41, so that the amount of light of the laser diode 21 can be detected by the monitor diode 21. Fig. 6 (A)
As shown in FIG. 7, the laser diode 21 stops emitting light except during play. When not playing, the laser ON SW is connected to GND, and the emitter and the collector of the transistor Q1 conduct, so that the IC1 pin is almost at the GND potential, and since the pin is at the potential, the transistor Q2 is cut off and the laser diode 21 is cut off. No current flows through.

When playing, the emitter of transistor Q1 is a laser
It becomes almost 5V by ON SW, and IC1 pin becomes electric potential. This potential fluctuates according to a monitor current Im flowing through the monitor diode (a current flowing through the monitor diode when laser light is irradiated). When the pin becomes a potential, the pin also becomes a potential, the transistors Q1 and Q2 become conductive, and a current flows through the laser diode.

The current of the laser diode 21 is
As a change in the monitor current flowing through 41, the IC1 pin is controlled (so that the monitor current, that is, the amount of laser light becomes constant), and a current of approximately 60 to 100 mA flows in a steady state.

FIG. 7 shows an outline of the tilt servo. The disk 1 is not perfectly flat, but is somewhat curved. The laser beam emitted from the pickup cannot be perpendicularly incident on the disk due to the warpage of the disk 1. As a result, optical distortion occurs in the laser light spot on the disk surface, the level of the tracking error signal output from the pickup decreases, and a crosstalk phenomenon in which the signal of the adjacent track leaks appears, and the disk groove The following performance and image quality are deteriorated. Therefore, in order to prevent various signal deteriorations due to the warpage of the disk, it is necessary to correct the inclination of the entire pickup according to the inclination due to the warpage of the disk.

The detection of the tilt of the disk is performed by a detector mounted near the objective lens actuator as shown in FIG. This detector includes a light emitting diode 44 and a pair of light receiving elements 45. When the disk 1 is in a warped state, the output of the light emitting diode 44 reflected by the disk and returned to the light receiving element 45 differs between the left and right sides of the light receiving element 45. Therefore, the inclination of the disk 1 can be taken out as a difference current between the output currents of both light receiving elements. The tilt mechanism is driven by this signal current, and is tilted in accordance with the tilt of the pickup disk. In this example, this signal current is extracted as a tilt error signal.

Further, as shown in FIG. 1, the pickup head is provided with a head position detection sensor 15 for generating position data r of the pickup optical system 2. Since this head moves linearly in the radial direction, a magnetoscene, for example, can be used as the sensor 15 thereof. The various detection signals described above are converted into digital signals by an A / D converter and stored in the data storage device 4.

Next, the operation of the embodiment of the present invention will be described with reference to FIG. 1 and FIG. 8 to FIG.

When the motor 13 is started by power input and the optical disc 1 to be measured rotates at a steady speed, the laser diode 21
A light beam from the optical disk 1 is irradiated through the optical system 2 toward a pit on the track of the optical disk 1, and the reflected light is received by the photodiode 29 (see FIG. 5) of the detecting device 3.
The detection device 3 receives the reflected light while moving in the radial direction of the optical disc 1 at a predetermined speed synchronized with the rotation speed of the motor 13. At this time, since the optical system 2 and the detecting device 3 are housed in the same housing, they move together.

Along with the above operation, the tracking error signal, the focus error signal, the tilt error signal (hereinafter referred to as an ER signal), and the pit presence / absence signal (RF signal) are read from the optical disk 1 by the RF signal reading position signal (RF signal). That is, the signal is converted into a digital signal by the A / D converter 9 together with the r signal and the θ signal as the pit position data) and stored in the data storage device 4. At the same time, the RF signal is reproduced by the demodulator 5 into a video signal (video signal) VD and an audio signal (audio signal) AD, and the video signal VD is stored in the frame memory 6.

When the above reading and storing operations on the optical disk 1 to be measured are completed and the operator turns on the operation key 8,
The personal computer (personal computer) 7 is started, and the personal computer 7 reproduces the reproduced video signal VD stored in the frame memory 6 and the detection signal E stored in the data storage device 4.
As shown in FIG. 8, the R and RF signals and the position signals r and θ are fetched while corresponding on the same time axis, and the reproduced video signal VD is displayed on the CRT 11 for displaying images.

When the operator (observer) visually observes the images projected one after another on the CRT 11, searches for a portion of the image that looks unusual, and turns the operation key 8 OFF (stop).
As shown in FIG. 9, a still image is displayed on the screen, and a position detection cursor (indicated by +) created by the personal computer 7 is superimposed on the screen by using a cursor key (not shown) on the above-mentioned unusual part. Then, as shown in FIG. 10, the personal computer 7 determines the presence or absence of the bit string information on the disk 1 indicated by the position detection cursor on the CRT 12 based on the detection signals ER and RF and the position signals r and θ. Project.

Next, the personal computer 7 calculates the degree of pass / fail by comparing the data of the detection signal of the abnormal portion displayed on the CRT 12 with a preset standard value, and displays the determination result on the CRT 12. Alternatively, the personal computer 7 creates a new standard for determining the quality of the disc 1 based on the abnormal portion indicated by the cursor, and
It is displayed on the CRT 12 and printed out by a printer (not shown).

Further, as shown in FIG. 11, in accordance with an instruction position detecting cursor above, the personal computer 7 detects signal ER corresponding to the defective portion indicated by V _E on the reproduced video signal VD shown in FIG. 8
・ Extract RF signal and position data r ・ θ, and based on these extracted signals, convert the abnormal signal amount into a shape amount and convert it to a track shape image that can be enlarged and displayed on the CRT 12 screen together with its position data. . Here, since the track distortion amount being displayed can be calculated from the position data r · θ, the personal computer 7 determines the quality of the track distortion amount based on a preset standard value, and displays the determination result on the CRT 12. be able to.

Further, the signal read from the data storage device 4 includes a tracking error signal indicating whether or not the pickup is located at the position on the track where the signal is recorded as described above, and the focus of the laser spot on the disk surface. Focus error signal indicating whether or not
There are a tilt error signal indicating the degree of inclination of the disk surface, an RF signal indicating the presence or absence of pits on the disk, an r signal indicating the position of the pickup in the disk radial direction, and a θ signal indicating the position of the pickup in the disk circumferential direction. A reference value as a criterion for determining whether or not the signal is a defective portion or an abnormal portion is previously set in an internal ROM or the like, and the personal computer 7 reads the signal from the data storage device 4 based on these reference values. Each signal is automatically inspected, and the image of the CRT 11 is stopped at a point exceeding the reference value, and the data of the abnormal state at that position is stored in a CR, for example, as shown in FIG. 9 or FIG.
It can also be displayed on T12. In this case, if the operator confirms the display screen and presses the operation key 8, the above-mentioned automatic inspection is resumed and stopped again when the abnormality is detected. When the above operation is completed, the inspection result displayed on the CRT 12 may be printed out from a printer (not shown).

The processing functions of the personal computer 7 include, for example, the following programs. Calculation and display of the physical distance between each data, measurement of measurement position, range, accuracy, modulation ratio indication, calculation of indicator area, enhancement of display contents, enlargement / reduction of screen, data processing (average value, standard deviation, maximum , Minimum), search for the data part over the specified length and below
Classification of pit intervals and filing of count data of the number of pits between designated positions.

The data items calculated and displayed by the personal computer 7 include, for example, the following. Track shape (radial direction
0.1 μm accuracy), track pitch (0.1 μm accuracy),
Pit width (radial length) (0.1 μm accuracy), eccentricity (1 μm accuracy), unevenness of disk surface (0.2-100 μm)
Accuracy), disk surface inclination (circumferential, radial),
Pit length (circumferential direction) (accuracy of 0.1 μm), distance between pits (circumferential direction) (accuracy of 0.1 μm), coordinates of data extraction position (approximately 0.1 μm).

Further, the same optical system as that of an ordinary optical disk player can be used as the optical system 2, and the hard disk of the personal computer 7 can be used as the data storage device 4.
Since the detection device 3 can have the same configuration as that of an ordinary optical disk player, the device of the present invention can be configured relatively inexpensively and simply.

In the above-described embodiment of the present invention, a read-only optical disk having pits (holes) is exemplified as the optical disk 1. However, the optical disk to be measured in the present invention is not limited to this. For example, an organic dye material may be used. It is needless to say that the present invention can be applied to a write-once optical disk, a rewritable magneto-optical disk, a rewritable optical disk using a phase transition phenomenon or an organic dye material, and the like.

[Effects of the Invention] As described above, according to the present invention, a video signal obtained by reproducing a recording signal of an optical disk and various detection signals detected at the same time are taken out and stored together with a position signal of a pickup, and then a reproduction signal is obtained. The readout signal and readout signal are read out while corresponding to the detection signal and the position signal on the same time axis, and the reproduced image is displayed and various inspection processes are performed. The relationship between the defective part and the defective part on the reproduction signal can be easily recognized, and a more appropriate inspection can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an optical disk inspection apparatus according to one embodiment of the present invention. FIG. 2 is a perspective view showing an example of the configuration of an optical system and a detection device shown in FIG. (B) and (C) are explanatory diagrams showing the operation of the four-division photodiode in the photodiode in FIG. 2, FIG. 4 is an explanatory diagram showing the operation of the three photodiodes in FIG. 2, and FIG. FIG. 6 is a circuit diagram showing a configuration example of a detection circuit of the detection device of FIG. 1, FIGS. 6A and 6B are circuit diagrams and explanatory diagrams showing the configuration of the laser generation circuit of FIG. 2, and FIG. 1 is a cross-sectional view showing a configuration example of a sensor that generates a tilt error signal which is one of the ERR signals in FIG. 1. FIG. 8 is a waveform of a signal read out synchronously from a frame memory and a data storage device by the personal computer in FIG. FIG. 9 is a timing chart showing an example. FIG. 10 is an explanatory diagram showing an example of display output, FIG. 10 is an explanatory diagram showing an example of correspondence between the display image of FIG. 9 and an error portion of the detection signal, and FIG. 11 is another example of display output in the embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical system, 3 ... Detection device for light reception, 4
... data storage device, 5 ... demodulator, 6 ... frame memory,
7: Personal computer (PC), 8: Operation keys, 9: A / D converter, 11, 12: Display device (CRT), 13
… Disc rotating motor, 14,15… sensor, 21… laser diode, 29… photodiode, 44… light emitting diode, 45… light receiving element.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/18 572 G11B 20/18 572F

Claims (3)

(57) [Claims] An optical system for irradiating a light beam on a rotating optical disk at a predetermined speed and receiving reflected light from the optical disk, a moving position of a pickup of the optical system in a disk radial direction, and rotation of the optical disk A sensor unit for detecting a position; a demodulation unit for demodulating a reproduction signal from a signal obtained from the optical system; a first storage unit for storing the reproduction signal; and one or more detection signals obtained from the optical system A second storage unit for storing the position data obtained from the sensor unit; a display unit for displaying the reproduction signal as an image; and sequentially displaying the reproduction signal stored in the first storage unit. Means for displaying the detection signal and the position data stored in the second storage means in synchronization with the reproduction signal and performing a predetermined inspection process at the same time as displaying the data on the reproduction means. Optical inspection apparatus characterized by comprising a stage. 2. A first instruction means for stopping a video being displayed on the display means in the middle, and a position of a defective portion in a still image of the display means which is stopped by an instruction of the first instruction means. The second control means, and the arithmetic control means extracts the detection signal and the position data corresponding to the defective part in the reproduction signal specified by the second specification means, and 2. The optical disk inspection apparatus according to claim 1, wherein the optical disk inspection apparatus converts the information into graphic information indicating the degree and displays the information on a second display unit. 3. A reference value setting means for presetting a reference value for disk inspection with respect to at least one kind of the detection signal, wherein the arithmetic control means determines a level of the detection signal taken in and a reference value. The optical disk inspection apparatus according to claim 1, wherein a pass / fail judgment is made by comparing.