JP2683039B2 - Optical disc inspection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inspection device for inspecting an optical disk such as an optical disk or a compact disk for defects.

(Prior art)

For example, a conventional optical disk inspection apparatus vertically irradiates an optical disk 4 through a polarization beam splitter 2 and a focusing lens 3 from a laser light source 1 which generates light having a certain polarization plane, as shown in FIG. Then, the reflected light is received via the polarization beam splitter 2. When the optical disc 4 is irradiated with a light source having linearly polarized light, the reflected light has all the polarized components, so a part of the light is given to the photoelectric converter 5 via the polarization beam splitter and converted into an electric signal. It is provided to the signal processing unit 6. In the signal processing unit 6, the optical disc 4 is rotated by the rotation control mechanism 7, and the optical system or the optical disc 4 is scanned in the radial direction of the optical disc to identify the size of the defect from the reflected light level and the number of times the level is lowered. The number was detected by.

[Problems to be solved by the invention]

However, in such a conventional optical disc inspection device,
Since the laser beam is vertically incident on the optical disc, only the size and number of defects occurring in the optical disc can be inspected, and the type and position of the defect cannot be accurately determined.

The present invention has been made in view of the problems of the conventional optical disk inspection apparatus described above, and it is a technical object to make it possible to accurately determine not only the number of defects of an optical disk but also its type and position. To do.

[Means for solving the problem]

The invention according to claim 1 of the present application is an inspection device for inspecting an optical disk for defects, comprising: a rotation driving means for rotationally driving the optical disk; A light source that tilts and irradiates, a first photoelectric conversion element that detects reflected light that is reflected from the surface of the optical disk when irradiated by the light source, and a second photoelectric conversion element that receives diffracted light from a pit surface formed on the optical disk. A photoelectric conversion element, a polarization beam splitter that separates reflected light from the pit surface of the optical disc into reflected light having the same polarization component as the light source and reflected light of other components, and a light source separated by the polarization beam splitter. A third photoelectric conversion element that receives reflected light of the same polarization component and a fourth photoelectric conversion element that receives reflected light of another polarization component separated by the polarization beam splitter. And a pinhole on the pit surface of the optical disk is detected based on the decrease in the light receiving levels of the second and third photoelectric conversion elements, and the pit pattern of the optical disk is damaged based on the decrease in the light receiving level of the second photoelectric conversion element. To detect a defect on the surface of the optical disc based on the decrease in the light receiving levels of the first, second and third photoelectric conversion elements, and to detect the second, third
Defect detection means for detecting bubbles in the resin film of the optical disk based on the decrease in the light reception level of the photoelectric conversion element and the increase in the light reception level of the fourth photoelectric conversion element. The invention of claim 2 of the present application is configured by removing the second photoelectric conversion element from the invention of claim 1.

[Action]

According to the invention of claim 1 of the present application having such a feature, the light beam of the linearly polarized light component is irradiated from a direction inclined by a predetermined angle with respect to the vertical surface of the optical disk, and the reflected light on the surface is subjected to the first photoelectric conversion. The element receives the light and separates it into the reflected light from the pit surface formed in the optical disk. Then, the diffracted and reflected light of the reflected light from the pit surface is detected by the second photoelectric conversion element, and the reflected light having the same polarization component as the light source is reflected by the third photoelectric conversion element and the polarization component different from that. The light is separated and received by the fourth photoelectric conversion element.

By doing so, the pinholes existing on the pit surface of the optical disc are detected based on the decrease of the reflected light level obtained from the second and third photoelectric conversion elements, and the pit surface formed on the optical disc is not damaged. It is detected based on a decrease in the output of the second photoelectric conversion element. If there is a defect on the surface of the optical disk, it is detected based on the decrease in the output of the first to third photoelectric conversion elements, and if there is a defect such as a bubble inside the optical disk, the second and third photoelectric conversion elements are detected. It can be detected when the reflected light level of the element decreases and the reflected light level of the fourth photoelectric conversion element increases.

Further, in the invention of claim 2 of the present application, as in the invention of claim 1, a light beam having a linear polarization component is irradiated from a direction inclined by a predetermined angle with respect to the vertical surface of the optical disk, and the surface reflected light is subjected to the first photoelectric conversion. Light is being received by the element. Of the reflected light from the pit surface, the reflected light having the same polarization component as the light source is the third photoelectric conversion element, and the reflected light having a different polarization component is the fourth.
The light is separated and received by the photoelectric conversion element. In this way, if there are pinholes on the pit surface of the optical disc, or if there are surface defects or defects such as bubbles inside the optical disc, it is possible to detect each defect and eliminate the rare pit damage. And other damage will be detected.

[Explanation of Example]

FIG. 1 is a perspective view showing an optical system of an optical disc inspection apparatus according to an embodiment of the invention of claim 1 of the present application. In this embodiment, a laser light source having a linearly polarized component, for example, a He-Ne laser 11, is used as a light source, and the laser beam is given to a focusing lens 13 via a prism 12 having an elliptical light diameter. The light focused by the focusing lens 13 is emitted from the lower surface of the optical disc 14. The irradiation direction of this laser beam is assumed to be inclined at a predetermined angle θ with respect to the y-axis perpendicular to the optical disc 14, and for example, as shown in FIGS. 1 and 2, the x-axis perpendicular to the radial direction of the optical disc 14 is shown. It is assumed that the optical disc 14 is irradiated with the laser beam from the position above. Then, a first photoelectric conversion element is provided at a position where the reflected light from the surface of the optical disk 14 is received via the focusing lens 13.
For example, the photodiode PD1 is arranged. Also optical disc 1
The position where the diffracted reflected light is received among the reflected light from the surface 14b (hereinafter referred to as a pit surface) on which a predetermined pattern is formed by vapor-depositing aluminum or the like across the resin film 14a of 4, namely, the z direction in the radial direction. The photodiode PD2 which is the second photoelectric conversion element is arranged on the yz plane formed by the y-axis.
Further, the reflected light from the pit surface 14b is guided to the polarization beam splitter 15 via the focusing lens 13. Polarizing beam splitter 15
Is for transmitting the regular reflection light in which the polarization component of the laser light source 11 which is a light source is stored as it is, and for reflecting the light of the polarization component perpendicular thereto. The photodiode PD3, which is the third photoelectric conversion element, is provided at the position for receiving the specular reflection light, and the photodiode PD4, which is the fourth photoelectric conversion element, is provided at the position for receiving the reflected light of the polarization component perpendicular to the third photoelectric conversion element. Then, the optical disc 14 is driven at a predetermined speed by the rotation control mechanism 16 which is rotationally driven. The optical disk 14 and the rotation control mechanism 16, or the laser light source 11 to the polarization beam splitter 15
The photodiodes PD1 to PD4 are gradually moved in the z-axis direction to scan the entire surface of the optical disc 14.

Next, FIG. 3 is a diagram showing a signal processing section which constitutes a defect identifying means for detecting a defect of the optical disk 14 based on signals from these photodiodes. In the figure, the outputs of the photodiodes PD1 to PD4 are given to the I / V converters 21 to 24, respectively. The I / V converters 21 to 24 are photodiodes P, respectively.
The outputs of D1 to PD4 are converted into voltage signals and amplified, and the outputs are given to the comparators 25 to 28. Comparator 25
A constant threshold level is set for each of -28, and a given signal is converted into a binary signal. Comparator 25 ~
The outputs of 28 are given to 4-input type AND circuits 29 to 32, respectively. The AND circuits 29 to 32 determine the type of defect on the optical disk 14 based on this logic signal.

Next, the operation of this embodiment will be described with reference to FIGS. When inspecting an optical disk, the rotation control mechanism 16 is driven to rotate the optical disk 14 at a constant speed and the laser light source 11 is driven. The light from the laser light source 11 passes through a prism 12 and a focusing lens 13 and an optical disc 14
Is irradiated. If the optical disk to be inspected has no defect, surface reflected light of a certain level is obtained from the optical disk 14, and the light irradiated to the inside is reflected by the pit surface 14b. When a predetermined pit pattern is formed on the pit surface, diffracted light is obtained and received by the photodiode PD2. Further, the regular reflection light of the pit surface 14b has its polarization component preserved, and thus is received by the photodiode PD3 via the polarization beam splitter 15.

Now, as shown in FIG. 4 (a), when the pinhole is located on the pit surface of the optical disk 14, FIG.
As shown in (c), the output of the photodiode PD1 does not decrease, and the light amount levels of the diffracted light detected by the photodiode PD2 and the regular reflection light detected by the photodiode PD3 decrease. Therefore, the pinhole defect can be detected by the AND circuit 31.

Next, when the pit pattern of the optical disc 14 is damaged as shown in FIG. 4 (b), the surface reflected light level received by the photodiode PD1 does not change as shown in FIG. 6 (a). As shown in FIGS. 6 (b) and 6 (c), the level of the diffracted light obtained by the photodiode PD2 decreases, and the level of the specularly reflected light obtained by the photodiode PD3 correspondingly rises slightly. However, at this time, since the polarization component is preserved, the light receiving level of the photodiode PD4 is kept low. Therefore, such a signal change is detected by the AND circuit 32.

Further, as shown in FIG. 4 (c), when there is a defect on the surface of the optical disk 14, the irradiation light is diffusely reflected on the surface, and the photodiode PD that receives the reflected light from the surface is received.
The level of 1 decreases. Also through this defect the optical disc 1
Since the level of the laser light incident on the resin film 14a of No. 4 also decreases, the level received by the photodiodes PD2 and PD3 also decreases as shown in FIGS. 7 (b) and 7 (c). However, the reflected light, which is received by PD4 and whose polarization plane is rotated, is hardly received and the original state is maintained. Therefore, such a state change can be detected by the AND circuit 29.

Further, as shown in FIG. 4 (d), when there are defects such as bubbles in the synthetic resin surface of the optical disk 14, changes in the reflected light level are shown in FIGS. 8 (a) to 8 (d). The surface reflected light level of the photodiode PD1 does not change,
The light reception level of diffuse reflection light and regular reflection light received by the photodiodes PD2 and PD3 is lowered. However, since the polarization direction of light changes due to the bubbles, the light reception level of light received by the photodiode PD4 via the polarization beam splitter 15 increases. Therefore, such a change
Can be detected by 30. As described above, in the present invention, light is irradiated from a position inclined by a predetermined angle from the surface of the optical disc, four photoelectric conversion elements are provided, and the type of defect is identified by the relationship of the light receiving level of the photoelectric conversion elements.
These outputs may be counted as they are and output to the outside, or some kind of statistical processing may be performed.

Next, the ninth embodiment of the invention according to claim 2 of the present application will be described.
This will be described with reference to the drawings. 9, the same parts as those in FIG. 1 are designated by the same reference numerals. Also in this embodiment, the laser light source 11 is irradiated with laser light through a prism 12 and a focusing lens 13 from a direction inclined by a predetermined angle from a line perpendicular to the front surface of the optical disc 14, and the type of defect is determined based on the reflected light level. The detection is the same as in the first embodiment described above.
In this embodiment, a photodiode PD1 which is a first photoelectric conversion element is provided in order to receive the surface reflected light reflected from the surface of the optical disk 14. Further, the reflected light from the pit surface is separated via the polarization beam splitter 15 by the difference in the polarized surface. A photodiode PD3, which is a third photoelectric conversion element that detects specularly reflected light that passes through the polarization beam splitter 15, and a photodiode PD4 that is a fourth photoelectric conversion element, which detects reflected light reflected by the polarization beam splitter 15. To provide. The signal processing circuit is the same as that of the above-described embodiment except the I / V converter 22 and the comparator 26 that process the output of the photodiode PD2. In this embodiment, the damage of the pit pattern cannot be detected as shown in FIGS. 4 (b) and 6. However, since such damage is extremely unlikely to occur, defects of the optical disk other than the second photoelectric conversion element PD2 facing them are detected.

〔The invention's effect〕

Therefore, according to the invention of claim 1 of the present application, it is possible to determine the type and position of the defect on all surfaces of the optical disk by moving the optical system or the optical disk itself in the radial direction while rotating the optical disk. The invention of claim 2 has an effect that it is possible to determine the position and type of other damage except for the damage on the pit surface which hardly occurs.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical system of a disc inspection apparatus according to an embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a block diagram showing the structure of defect identifying means, and FIG. 4 (a). ，
(B), (c), and (d) are diagrams showing types of damage to the optical disk, and FIGS. 5, 6, 7, and 8 show photoelectric conversion elements PD1 to PD4 for damage to the optical disk, respectively. FIG. 9 is a perspective view showing an optical system of an optical disc inspection apparatus according to an embodiment of the invention of claim 2 of the present application, and FIG. 10 is a block diagram showing a configuration of a conventional optical disc inspection apparatus. . 11 ... Laser light source, 12 ... Prism, 13 ... Focusing lens, 14 ... Optical disk, 15 ... Polarization beam splitter,
16 …… Rotation control mechanism, PD1-PD4 …… Photodiodes

Claims (2)

(57) [Claims] 1. A rotation driving means for rotating an optical disk, a light source for generating a light beam having a linearly polarized light component and irradiating the light beam at a predetermined angle with respect to the surface of the optical disk, and a surface of the optical disk when irradiated by the light source. The first photoelectric conversion element for detecting reflected light reflected, the second photoelectric conversion element for receiving diffracted light from the pit surface formed on the optical disc, and the same light source as the reflected light from the pit surface of the optical disc A polarization beam splitter that separates the reflected light having a polarization component of and a reflected light of another component, and a third photoelectric conversion element that receives the reflected light of the same polarization component as the light source separated by the polarization beam splitter. A fourth photoelectric conversion element that receives reflected light of another polarization component separated by the polarization beam splitter, and a light reception level of the second and third photoelectric conversion elements. Detects pinholes on the pit surface of the optical disc based on the drop,
Damage to the pit pattern of the optical disc is detected based on the decrease in the light receiving level of the second photoelectric conversion element,
Defects on the optical disk surface are detected based on the decrease in the light reception levels of the second and third photoelectric conversion elements, and the decrease of the light reception levels of the second and third photoelectric conversion elements and the light reception of the fourth photoelectric conversion element. An optical disc inspection apparatus comprising: a defect identification unit that detects bubbles in a resin film of an optical disc based on a rise in level. 2. A rotation driving means for rotating and driving an optical disk, a light source for generating a light beam having a linearly polarized light component and irradiating the light beam at a predetermined angle with respect to the surface of the optical disk, and a surface of the optical disk when irradiated by the light source. A first photoelectric conversion element that detects reflected light that is reflected, and a polarization beam splitter that separates the reflected light from the pit surface of the optical disc into reflected light having the same polarization component as the light source and reflected light of other components. A third photoelectric conversion element that receives reflected light of the same polarization component as the light source separated by the polarization beam splitter, and a fourth photoelectric conversion element that receives reflected light of another polarization component separated by the polarization beam splitter. A pinhole on the pit surface of the optical disc is detected based on a decrease in the light receiving level of the photoelectric conversion element and the third photoelectric conversion element,
Defects on the surface of the optical disc are detected based on the decrease in the light receiving level of the third photoelectric conversion element, and based on the decrease in the light receiving level of the third photoelectric conversion element and the increase of the light receiving level of the fourth photoelectric conversion element. An optical disc inspection apparatus comprising: a defect identification unit that detects bubbles in a resin film of an optical disc.