JP2653026B2 - Optical information recording disk inspection method and inspection apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method and an inspection apparatus for inspecting scratches on the surface of an optical information recording disk and defects generated in an internal recording layer.

[0002]

2. Description of the Related Art Optical information recording disks include a read-only optical disk (hereinafter referred to as a ROM type optical disk) for reading information recorded on the disk, and an optical disk (hereinafter referred to as a RAM) capable of recording information. Type optical disk). The former ROM-type optical disk includes a light-transmitting substrate formed of, for example, polycarbonate, a reflective film formed by evaporating aluminum or gold, a protective layer for protecting the reflective film, and the like. Also,
The latter RAM type optical disk has a light-transmitting substrate formed of polycarbonate, a recording layer formed by coating an organic dye, and a reflective film formed by evaporating aluminum or gold.
It is composed of a protective layer for protecting the reflection film.

[0003] By the way, when such a ROM-type optical disk is reproduced or recorded or reproduced on a RAM-type optical disk, the surface of the light-transmitting resin substrate through which the light beam for reproduction or recording passes is damaged. If there is, or dust is mixed in the resin substrate, or a minute hole (pinhole) is generated in the reflection film, accurate reproduction and recording of information cannot be performed. Therefore, in the process of manufacturing the ROM type optical disk, the RAM type optical disk, and the like, it is necessary to inspect for defects such as scratches, dust, and pinholes.

Conventionally, as a method of inspecting such a defect, for example, light from a halogen lamp is irradiated through a slit onto the surface of an optical disk to be inspected, and reflected light or transmitted light is received by a CCD camera or the like. A semiconductor laser is used as a light source, the laser light is reflected by a polygon mirror, etc., and the surface of the inspection object is scanned, and the reflected light or transmitted light is received by the light receiver Inspection methods have been implemented.

[0005] The principle of such an inspection method is as follows. That is, light passed in a band shape by a slit or a polygon mirror is applied in the radial direction of an optical disk as an inspection object, and light is applied to the entire surface of the optical disk while rotating the optical disk once. At this time, if there is no defect in the light-transmitting substrate or the reflective film of the optical disk, the intensity of the reflected light is uniform, and the output of the light receiver is also uniform. On the other hand, when a defect such as a scratch occurs, the irradiation light is irregularly reflected at that portion, and the reflectance at that portion is particularly reduced. That is, the intensity of the reflected light is not uniform, and the output of the reflected light received by the CCD camera and converted into an electric signal is reduced at that portion. Thus, the electric signal can be processed by a computer to determine whether there is a defect.

[0006]

In contrast to the ROM type optical disk described above, a recordable RAM type optical disk has a recording layer formed between a translucent substrate and a reflective film. It is desired that the thickness of the recording layer is constant at any portion on the recording layer forming surface, and the tolerance of the thickness is very strictly controlled. This is because if the thickness of the recording layer is uneven, correct recording is not performed, and a problem occurs in that recorded information is reproduced incorrectly or cannot be reproduced.

When this recording layer is formed by applying an organic dye, it is difficult to prevent the occurrence of coating unevenness. For example, as one method of forming this recording layer on a disc-shaped translucent substrate, an organic dye is formed in the radial direction on the disc surface while rotating at high speed around the center of the disc-shaped substrate. In this case, a so-called spin coating method or the like for applying a recording layer material is used, but in this coating, a coating unevenness like a radial “tail” may occur.

However, the difference between the reflectivity of a recording layer having such a coating unevenness and the reflectivity of a normally applied recording layer is due to the reflection between the scratched portion and the normal portion as described above. Significantly smaller than the rate difference. Therefore, such a defect cannot be detected by the conventional inspection method as described above. This is because the inspection light conventionally used has low sensitivity to the difference in the thickness of the recording layer, so even if the thickness of the recording layer is different, it passes through the recording layer and is reflected by the reflection film. This is because the change in the light received by the light receiving unit is small.

In view of the above-mentioned problems of the prior art, the present invention provides a recordable RAM type optical disk.
An object of the present invention is to provide an inspection method and an inspection apparatus for an optical information recording disk capable of inspecting not only defects existing in the light-transmitting substrate and the reflection film but also irregularities in the coating thickness of the recording layer.

[0010]

That is, according to the present invention, as a method for achieving the above object, there is provided an optical information system in which at least a recording layer and a reflective film are sequentially formed on a translucent substrate. In the method for inspecting a recording disk, the recording layer is inspected by irradiating the recording layer with first inspection light having a wavelength absorbed by the material forming the recording layer, and measuring the light reflected from the reflection film. The first inspection and the second inspection light having a wavelength hardly absorbed by the material forming the recording layer are passed through the light-transmitting substrate, and the light reflected from the reflection film is measured to inspect the light-transmitting substrate. And an inspection method for an optical information recording disk, comprising:

Further, as an apparatus for carrying out the above-described inspection method of the present invention, there is provided an inspection apparatus for inspecting an optical information recording disk in which at least a recording layer and a reflection film are sequentially formed on a light-transmitting substrate. A first light source that irradiates the recording layer with inspection light having a wavelength absorbed by the material forming the recording layer, and a first light receiver that receives reflected light from the reflection film of the inspection light and measures the light. A second light source that irradiates the light-transmitting substrate with inspection light having a wavelength that is hardly absorbed by the material forming the recording layer, and a second light that receives reflected light from the reflection film of the inspection light and performs measurement. There is proposed an optical information recording disk inspection apparatus, which is provided with a light receiver.

[0012]

According to the method and apparatus for inspecting an optical information recording disk according to the present invention, the first light source irradiates the recording layer with the first inspection light having a wavelength particularly absorbed by the material forming the recording layer. Then, the reflected light is received by the first light receiver, and the presence or absence of coating unevenness of the recording layer made of the organic dye can be determined by the first inspection step of measuring. That is, when there is a difference in the film thickness of the recording layer, the difference in the film thickness can be determined from the difference in the amount of absorption of the inspection light when the inspection light is transmitted through the recording layer.
On the other hand, from the second light source, by irradiating the light-transmitting substrate with inspection light having a wavelength not absorbed by the recording layer material, receiving the reflected light with a second light receiver, and measuring the second inspection step, The inspection light is not absorbed by the organic dye that forms the recording layer, and therefore, is not disturbed by the recording layer, so that it is possible to inspect for a flaw on the light-transmitting substrate and dust inside the light-transmitting substrate.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an inspection apparatus for implementing the optical information recording disk inspection method of the present invention,
Here, the optical information recording disk 100 to be inspected is a recordable RAM type optical disk. As shown in FIG. 5, this optical information recording disk 100 is coated with a light-transmitting resin substrate 110 made of, for example, polycarbonate in a disc shape, and is coated with a uniform thickness on one main surface of the light-transmitting resin substrate. A recording layer 120 made of, for example, an organic dye, a reflection film 130 formed by evaporating aluminum or gold on the back surface of the recording layer 120, and a protective film 140 provided on the reflection film 130. I have.

As shown in FIG. 1, the optical information recording disk 100 is mounted on a rotatable rotating plate 10. Above the rotating plate 10, a first light irradiating section 20 and a second light irradiating section 30 are provided, and beside these, a first light receiving section 40 and a second light receiving section are provided, respectively. 50 are arranged correspondingly. In this figure, reference numeral 60 denotes a motor for rotating the rotary plate.
The rotation of the rotating shaft is transmitted to the rotating shaft of the rotating plate 10 via a torque transmission mechanism 65 such as a reduction gear, and rotates the rotating plate at a predetermined speed. An electric signal output by receiving the inspection light by the first and second light receiving units 40 and 50 is input to, for example, a control unit 70 including a computer, and is analyzed and inspected according to a predetermined program. . The control unit 70 controls the rotation of the motor 60 via a motor control circuit 80.

The first light irradiating section 20 is provided with a light source for generating light having a wavelength showing a particularly high absorptivity to an organic dye which is a material for forming the recording layer 120 of the optical information recording disk 100, On the other hand, the second light irradiation unit 30
The recording layer is provided with a light source that generates light having a wavelength that is hardly absorbed by the material. The first light irradiation unit 20
For example, as shown in FIG. 2, light from a semiconductor laser 21 as a light source is reflected by a rotating polygon mirror 22, and further,
As shown by a broken line, the light is incident on the surface of the transparent substrate 110 of the optical information recording disk 100 through the plane mirror 23 and the concave mirror 24 curved inward in the radial direction. That is, the laser beam from the semiconductor laser 21 can move in the radial direction of the optical information recording disk 100 from the center edge to the outer edge or in the opposite direction by rotating the polygon mirror 22. Done
Thus, it is possible to scan the surface of the light transmitting substrate 110 of the optical information recording disk 100 in the radial direction.

On the other hand, the second light irradiating section 30 can also be configured by using a semiconductor laser with the same structure as that shown in FIG. However, the wavelength of the irradiation light is a light having a wavelength that is not absorbed by the material for forming the recording layer, and has a different wavelength from the light irradiated from the first light irradiation unit 20. As another example, as shown in FIG. 3, a halogen lamp 31 is used, the emitted light is made linear through a slit 33 of a slit plate 32, and this linear light is transmitted through the optical information recording disk 100. The surface of the optical substrate 110 may be irradiated in the radial direction.

The first and second light receiving sections 40 and 50 are
Although a line-type CCD camera as shown in FIG. 1 can be used, for example, as shown in FIG. 4, reflected light coming out of the transparent substrate 110 of the optical information recording disk 100 is reflected by using a concave mirror 41. The light may be reflected so as to converge at one point, and a normal CCD camera 42 may be arranged at the converging point.

An inspection method of the optical information recording disk inspection apparatus of the present invention described above and its principle will be described below. The optical information recording disk 100 to be inspected is placed on the rotating plate 10, and the light from the first light irradiating unit 20 and the second light irradiating unit 30 is applied to the disk while rotating the rotating plate 10. Scanning is sequentially performed from the inside to the outside in the radial direction. Thereby, the light emitted from the first light irradiating section 20 and the second light irradiating section 30 are reflected on the surface of the optical information recording disk 100 and the interface between the layers, respectively, and thereafter, respectively, And is received by the light receiving sections 40 and 50 of the light receiving section. Further, the first and second light receiving units 40 and 50 output electric signals corresponding to the respective amounts of received light, and the control unit 70
Performs an inspection for the presence or absence of a defect by a predetermined calculation based on the detection signal.

First, the inspection of the recording layer 120 by the first light irradiation unit 20 and the light receiving unit 40 will be described. The laser beam L emitted from the first light irradiating section 20 to the optical information recording disk 100 passes through the light transmitting substrate 110 of the optical information recording disk 100 as shown by an arrow in FIG. Is incident on the organic dye recording layer 120 and a part thereof is reflected at the interface, and then exits through the surface of the light transmitting substrate 110 (L ′). Further, a part of the light of the organic dye incident on the recording layer 120 is also reflected at the interface of the reflection film 130, passes through the light-transmitting substrate 110 from the recording layer 120 again, and exits from the surface to the outside (L "). ).

Here, as shown in the figure, the wavelength of the inspection light L is λ, the thickness of the organic dye recording layer 120 is d,
Assuming that the angle of incidence of the inspection light on the recording layer is θ, the optical path difference Δ between these two reflected lights (L ′ and L ″) is expressed by the following equation: Δ = 2 · dn · cos θ Here, n = n _P / n _D , where n _P is the refractive index of the translucent substrate, and n _D is the refractive index of the recording layer 120.

The two reflected lights L ′ and L ″ emitted to the outside interfere with each other, but when the optical path difference Δ satisfies the following condition, the phases coincide with each other and become brighter. Δ = 2 · dn · cos θ = (2m + 1) · λ / 2 where m is an integer.

Here, for example, by appropriately setting the incident angle of the laser beam L (ie, changing θ), the recording layer 120 is adjusted so as to obtain the maximum reflectance when the recording layer 120 has the specified thickness d. I can do it. As a result, when the thickness d of the recording layer 120 deviates from the specified value,
The two reflected lights L ′ and L ″ do not have the same phase, the brightness thereof changes, the reflectance decreases or increases, and the amount of light received by the light receiving unit 40 changes. By detecting that the output from 40 has changed with respect to a predetermined value, the film thickness of the recording layer 120 is different from the specified value;
That is, it is possible to inspect whether there is a difference in the film thickness due to uneven coating of the organic dye or the like. For example, the control unit 7
0 indicates that the received light amount A of the first light receiving unit 40 is changed in the temporal change of the received light amount shown in FIG. 6 (that is, the optical information recording disk 100 is scanned in the radial direction as the time t elapses). It is determined to be defective if the value falls below the first threshold Th1.

Next, the inspection of the light transmitting substrate 110 by the second light irradiating unit 30 and the light receiving unit 50 will be described. Light emitted from the second light irradiator 30 to the optical information recording disk 100 passes through the light transmitting substrate 110 and the recording layer 120 and reaches the reflective film 130. This light is reflected on the surface of the reflection film, passes through the light transmitting substrate 110 and the recording layer 120 again, and is received by the second light receiving unit 50. Since the light from the second light irradiator 30 is not absorbed by the organic dye material of the recording layer 120, most of the light passes through the recording layer 120 unless there is a defect such as a scratch or dust on the optical path. Then, the light is reflected by the surface of the reflective film 130 and the amount of light received by the second light receiving unit 50 becomes a large value.

On the other hand, when there is a scratch on the surface of the light transmitting substrate 110 of the optical information recording disk 100, dust mixed therein, and pinholes or the like generated in the reflection film 130, the above optical path is changed. The passing light is irregularly reflected, the reflectance is reduced, and the amount of light received by the second light receiving unit 50 is reduced. Therefore, the control unit 70 can accurately inspect the defects of the translucent substrate 110 and the reflective film 130 by detecting that the output from the second light receiving unit 50 has dropped below a predetermined value. I can do it. For example, the received light amount B shown in FIG.
If the amount of light received by the second light receiving unit 50 falls below the second threshold Th2 in the temporal change of, it is determined to be defective.

In the above embodiment, the inspection using the two types of inspection light is performed at the same time. However, the inspection method of the present invention is not limited to this. 20 and the light receiving section 40, the recording layer 1
20 is inspected, and then the second light irradiation unit 30 and the light receiving unit 50 are inspected.
Thus, the presence or absence of dust entering the translucent substrate 110 may be inspected.

[0026]

As is apparent from the above description, according to the optical information recording disk inspection method and inspection apparatus of the present invention,
The effect is obtained that the inspection of the recording layer of the RAM type optical disk by the optical means, which has been difficult to inspect conventionally, can be performed together with the inspection of the light-transmitting substrate and the reflection film.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an inspection apparatus for performing an optical information recording disk inspection method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a detailed structure of a first light irradiation unit of the inspection device.

FIG. 3 is a perspective view showing another structure of the second light irradiation unit of the inspection device.

FIG. 4 is a perspective view showing a detailed structure of a light receiving section of the inspection device.

FIG. 5 is a partially enlarged sectional view of the optical information recording disk showing the operation and principle of the optical information recording disk inspection method of the present invention.

FIG. 6 is a graph showing an example of a change in the amount of received light to explain the inspection operation of the optical information recording disk of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotating plate 20 First light irradiation part 21 Semiconductor laser 30 Second light irradiation part 40 First light receiving part 50 Second light receiving part 60 Motor 70 Control part 100 Optical information recording disk 110 Translucent substrate 120 Recording layer 130 Reflective film 140 Protective film

Continuation of the front page (72) The inventor Takashi Ishiguro 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Yuden Co., Ltd. (56) References JP-A-63-142554 (JP, A) JP-A-60-147945 ( JP, A) JP-A 1-179245 (JP, U) JP-A 60-106216 (JP, U)

Claims (3)

(57) [Claims] 1. A method for inspecting an optical information recording disk in which at least a recording layer and a reflection film are sequentially formed on a light transmitting substrate, wherein a first wavelength of a wavelength absorbed by a material forming the recording layer is provided. A first inspection step of irradiating the recording layer with the inspection light and measuring the reflected light from the reflection film to inspect the recording layer; and a second inspection step of a wavelength hardly absorbed by the material forming the recording layer. A second inspection step of passing the inspection light through a light-transmitting substrate, measuring reflected light from the reflection film, and inspecting the light-transmitting substrate and the reflection film. Inspection method. 2. The optical information recording disk according to claim 1, wherein the first inspection light and the second inspection light are respectively radiated in a radial direction of the optical information recording disk while rotating the optical information recording disk. An inspection method for an optical information recording disk, wherein the first and second inspection steps are performed simultaneously. 3. An inspection apparatus for inspecting an optical information recording disk in which at least a recording layer and a reflection film are sequentially formed on a light-transmitting substrate, to inspect a wavelength absorbed by a material forming the recording layer. A first light source for irradiating the recording layer with light,
A first light receiver for receiving and measuring the reflected light of the inspection light from the reflection film, and a second light-receiving substrate for irradiating the light-transmitting substrate with inspection light having a wavelength hardly absorbed by the material forming the recording layer. An inspection device for an optical information recording disk, comprising: a light source; and a second light receiver for receiving and measuring the reflected light of the inspection light from the reflection film.