JPH01206208A - Checking apparatus of optical information storage medium - Google Patents

Abstract

PURPOSE:To measure continuously an amount of displacement, such as an amount of warp and an amount of plane vibration, of an optical information storage medium, by a method wherein an optical head element is moved continuously in the direction of the radius of the optical information storage medium to detect a physical characteristic continuously. CONSTITUTION:An optical disk 1, a body to be checked, is rotated at a prescribed speed by a spindle motor 3. An optical head 9 is disposed on the back side of the optical disk 1 so that it faces the disk, and it is displaced after the displacement of the optical disk 1. By moving the optical head 9 at a prescribed speed in the direction of the radius of the optical disk 1 while the optical disk 1 rotates, the amount of displacement, such as plane vibration, of the optical disk 1 is checked continuously on the whole of the optical disk 1. A displacement amount detector 53 detects the amount of displacement in the direction of the radius of the optical disk 1 and the amount of displacement in the direction of the rotating axis of the optical disk 1 on the basis of displacement amount signals from a plurality of photosensors, and delivers to an arithmetic processing device 57 informations on these detected amounts of displacement.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an optical information storage medium inspection device for inspecting optical information storage media such as optical disks, and in particular to an optical information storage medium inspection device that inspects optical disks for displacement such as wobbling. The present invention relates to an optical information storage medium inspection device that continuously inspects the entire surface of an optical disk.

(Prior Art) In recent years, optical information storage media such as optical disks have been widely used in image information storage and retrieval devices, music or video playback devices, and the like. This optical disk is subjected to various quality inspections at the final stage of the manufacturing process using an optical information storage medium inspection device, for example, inspections regarding physical characteristics such as wobbling and warping.

Such a conventional optical information storage medium inspection device is equipped with a spindle motor that rotates an optical disk, which is an optical information storage medium, at a constant speed, and also performs tracking control and focusing control to control the rotation of the optical disk. In addition to being displaced to follow the displacement such as surface shooting,
The optical head section is provided so as to be movable in the radial direction of the optical disk by a moving means such as a feed motor.

When measuring the amount of displacement such as wobbling or warping of an optical disk, the moving means is driven to position the optical head section at a specific measurement point in the radial direction of the optical disk, and the optical head is positioned at a specific measurement point in the radial direction of the optical disk. The optical disc is rotated with the head section positioned, and the amount of displacement accompanying the rotation of the optical disc is measured. When the measurement of the amount of displacement at this specific measurement point is completed, the moving means is driven to move the optical head to the next measurement point, and the optical disk is moved with the optical head positioned at the next measurement point. Measure the amount of displacement associated with rotation.

Thereafter, the optical head section is sequentially moved to specific measurement points set in the radial direction of the optical disk in the same manner, and the amount of displacement of the rotating optical disk is measured while the optical head section is positioned at the specific measurement point.

(Problem to be Solved by the Invention) As described above, in the conventional optical information storage medium inspection device, it is assumed that there are multiple measurement points in advance in the radial direction of the optical disk, for example, a large amount of displacement at the outermost circumference. At the same time, the amount of displacement caused by the rotation of the optical disk was sequentially measured with the optical head section positioned at each of these measurement points.
If a large number of measurement points are set, it takes time to inspect the entire surface of the optical disc.

On the other hand, if the number of measurement points on the optical disk to be measured is set to a small number, measurement time can be shortened, but on the other hand, measurement may be omitted.

The present invention has been made in view of the above, and an object of the present invention is to provide an optical information storage medium inspection device that can quickly inspect the amount of displacement such as wobbling of an optical disk over the entire surface of the optical disk. .

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides a rotary drive means for rotationally driving an optical information storage medium as an object to be inspected; an optical head part that is displaced in accordance with physical characteristics; a moving means that continuously moves the optical head part in a certain direction related to the optical information storage medium; Detection means for detecting.

(Function) In the present invention, the rotation drive means rotates the optical information storage medium. It also includes a moving means for continuously moving the optical head section, which is displaced in accordance with the displacement caused by the rotation of the optical disk, in a certain direction relative to the optical information storage medium, for example, in the radial direction. Therefore, when the moving means is driven to continuously move the optical head section in the radial direction of the optical information storage medium, the detection means detects the physical state of the optical information storage medium according to the continuous movement of the optical head section. Detect characteristics continuously.

In other words, by continuously moving the optical head section in the radial direction of the optical information storage medium with respect to the rotating optical information storage medium, the amount of displacement such as surface runout is swirled over the entire surface of the optical information storage medium. The test is performed continuously in a (spiral) pattern.

(Example) Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

First, a schematic configuration of an optical information storage medium inspection apparatus to which the present invention is applied will be described with reference to FIG.

An optical disk 1, which is an optical information storage medium to be inspected, is placed on a spindle motor 3, and the spindle motor 3 is driven to rotate at a constant speed, for example, 600 rpm, thereby rotating the optical disk 1 at a constant speed. .

On the other hand, an optical head 9 and various optical systems are arranged on a base 7 that is movable by a feed motor 5. The laser head 11 outputs a laser beam for displacement measurement, for example, a parallel beam of He-Ne laser beam. When the beam splitter 13 receives the laser beam from the laser head 11, it equally distributes it in two directions and outputs it. One of the laser beams split by this beam splitter 13 is sent to an interferometer 15. Lens 17. The light is applied to the optical head 9 via total reflection prisms 19a and 19b. The incident light P1 that has entered the optical head 9 in this way is as shown in FIG.
A total reflection mirror 23 attached to a predetermined position of the optical head 9
reflected.

The reflected light reflected by the total reflection mirror 23 passes through the total reflection prisms 19b and 19a and the lens 17 again and travels to the interferometer 15. In the interferometer 15, the reflected light reflected by the total reflection mirror 23 and the laser light from the laser head 11 which is incident via the beam splitter 13 are caused to interfere with each other.

The light receiver 25 receives the interference light from the interferometer 15 and outputs a displacement signal of the optical head 9, that is, a signal corresponding to the eccentric displacement of the optical disk 1 in the radial direction.

The other laser beam distributed by the beam splitter 13 passes through a total reflection mirror 33. Interferometer 35. The light is applied to the optical head 9 via the lens 37 and the total reflection prism 19C.

As shown in FIG. 3, the incident light P2 that has entered the optical head 9 in this manner is vertically raised by a total reflection blob 41 disposed at a predetermined position of the optical head 9, and then further reflected by a total reflection mirror 43. reflected. The reflected light reflected by this total reflection mirror 43 is returned to total reflection prisms 41, 19c,
and passes through lens 37 to interferometer 35 . The interferometer 35 causes the reflected light reflected by the total reflection mirror 43 to interfere with the laser light from the laser head 11 that is incident via the total reflection mirror 33 and the beam splitter 13. The light receiver 45 receives the interference light from the interferometer 35 and outputs a displacement signal of the optical head 9, that is, a signal corresponding to the displacement of the optical disk 1 in the direction of the rotation axis. Further, the resolution of the interferometer 35 and the interferometer 15 is set to, for example, about 1/64 or 1/128 of the wavelength of light, respectively.

Next, with reference to FIG. 1, the device configuration and electrical circuit configuration of the main parts of the optical information storage medium inspection apparatus according to the present invention will be explained.

As shown in FIG. 1A, the optical disk 1 placed on the spindle motor 3 is formed into a disk shape with a diameter of 130 mm. Further, this optical disc 1 has spiral grooves 1a formed on both the front and back sides of the optical disc 1, as shown in FIG. 1B. The depth of this groove 1a is a value that is sufficiently smaller than the amount of displacement such as wobbling or warping of the optical disc 1 to be measured. Further, the spindle motor 3 rotates at a constant rotation speed within the range of 300 to 3600 rpm, thereby rotating the optical disc 1 at a constant speed. Also, the feed motor 5 has a speed of, for example, 0.01 per second.
By moving the base 7 at a constant speed within the range of ~1011111, the optical head 9 is moved at a constant speed in the radial direction of the optical disk 1. The amount of movement of the optical head 9 by the feed motor 5 is set to, for example, a maximum value of 200III11 in order to cover the information area of the optical disc 1.

The angle detector 51 detects the rotation angle of the optical disc 1 based on the output signal from the spindle motor 3. The displacement amount detector 53 is connected to the light receivers 25 and 45 shown in FIG. The amount of displacement in the direction of the rotation axis of 1 is detected.

The radial position detector 55 detects the radial position of the optical disk 1 where the optical head 9 is located based on the output signal from the feed motor 5. The arithmetic processing unit 57 includes an angle detector 51, a displacement ω detector 53, and a radial position detector 55.
The arithmetic processing unit 57 detects the optical disc 1 based on the detection signals from the angle detector 51, the displacement detector 53, and the radial position detector 55.
Executes arithmetic processing related to inspection.

Next, the operation of the embodiment will be explained with reference to FIGS. 4 and 5.

First, the optical disk 1, which is an object to be inspected, is placed on a spindle motor 3, and by rotating the spindle motor 3 at a constant speed, the optical disk 1 is rotated at a constant speed. An optical head 9 is disposed facing the back side of the rotating optical disc 1, and is displaced to follow the displacement of the optical disc 1. That is, the optical head 9 is subjected to force servo control and tracking servo control. Specifically, focuser water control is performed to maintain a constant distance between the objective lens (not shown) of the optical head 9 and the track surface on which W41a of the optical disc 1 is formed, and the focuser water control is performed to prevent eccentricity of the track described above. Tracking servo control is performed in which the objective lens is moved in the radial direction of the optical disc 1 for follow-up control.

Thereby, the optical head 9 follows the displacement of the rotating optical disk 1.

Next, by rotating the feed motor 5 at a constant speed, the optical head 9 is moved in the radial direction of the optical disk 1 at a constant speed. By moving the optical head 9 at a constant speed in the radial direction of the optical disc 1 with respect to the rotating optical disc 1, the amount of displacement such as surface waviness of the optical disc 1 can be controlled in a spiral shape over the entire surface of the optical disc 1. can be inspected continuously.

The displacement amount detector 53 detects the amount of displacement of the optical disc 1 in the radial direction and the amount of displacement of the optical disc 1 in the direction of the rotational axis based on the displacement amount signals from the light receivers 25 and 45, and provides information regarding the detected displacement amount. is sent to the arithmetic processing unit 57. Further, the radial position detector 55 detects the position of the optical disk 1 on which the optical head 9 is located based on the output signal from the feed motor 5.
The detected optical head 9
, that is, information regarding the distance from the center point of the optical disc 1 to the arithmetic processing unit 57.

FIG. 4 is an explanatory diagram showing the amount of displacement with respect to the distance from the center point of the optical disc 1. As shown in FIG. By moving the optical disc 1 to , the amount of displacement of the optical disc 1 can be continuously inspected.

FIG. 5 shows a case where another optical disk was inspected, and the continuous displacement amounts as shown in FIG. 4 were processed for each rotation period of the optical disk 1.

As shown in FIGS. 4 and 5, the arithmetic processing unit 57 calculates the deflection [1] and the warp IJ L 2 based on the respective information from the displacement amount detector 53 and the radial position detector 55. . That is, each time the optical disc 1 rotates, the calculation processing bag E57 calculates the difference between the maximum displacement amount and the minimum displacement amount corresponding to one rotation of the optical disc 1 as the surface runout fi.
As L + , this fluctuation I&L + is calculated for each rotation period of the optical disc 1. Further, the arithmetic processing unit 57 calculates the difference between the maximum amount of displacement and the minimum amount of displacement over the entire surface of the optical disc 1 as the warpage L2.

Note that in the embodiment described above, the optical disc 1 is
Although the case where the amount of displacement of the optical disk 1 is optically inspected is shown as an example, the present invention is not limited to this, but the present invention is configured to detect the amount of displacement of the optical disk 1 based on a signal from an appropriate sensor. be able to. For example, a similar configuration can be made in which the amount of displacement of the optical disc 1 is detected based on the values of currents flowing through the respective focus coils and track coils for executing focus servo control and tracking servo control.

(Effects of the Invention) As described above, according to the present invention, the optical head portion, which is displaced in accordance with the displacement accompanying the rotation of the optical information storage medium, is moved in the radial direction of the optical information storage medium. Since the physical characteristics of the optical information storage medium are continuously detected by moving the optical information storage medium continuously, the amount of displacement such as the amount of warpage and surface runout of the optical information storage medium can be measured by moving the optical information storage medium continuously. can be measured continuously and in a short period of time over the entire surface, improving the accuracy and usefulness of the measurement.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG. 2 (A
＞ is a plan view of an optical information storage medium inspection apparatus to which the embodiment shown in FIG. 1 is applied, FIG. 2 (8) is a side view of FIG. 2 (A), and FIG. Fig. 4 is an explanatory diagram showing the case where the amount of displacement is continuously detected over the entire surface of the optical disc, and Fig. 5 is an enlarged view of the main part shown. FIG. 1... Optical disk 3... Spindle motor 5... Feed motor 7... Base 9... Optical head 53... Displacement amount detector 55... Radial position detector 57... Arithmetic processing Device

Claims (1)

[Scope of Claims] Rotational driving means for rotationally driving an optical information storage medium as an object to be inspected; an optical head section that is displaced in accordance with the physical characteristics of the optical information storage medium; and the optical head section. An inspection of an optical information storage medium, comprising a moving means for continuously moving the optical information storage medium in a certain direction relative to the optical information storage medium, and a detection means for continuously detecting displacement of the optical head section. Device.