JPS63117336A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To detect a defect which becomes a defect in recording at the time of recording in real time by detecting a defect of an optical disk and the sticking of dust by utilizing an erasure beam. CONSTITUTION:A photodetecting element 19 detects the reflected light of a light spot M from the optical disk and the light is amplified by an amplifier 21 and applied to a detector 22. A light spot M for erasure is a longer circular spot than a spot L, but a light beam for erasure with constant power. The output of the amplifier 21 which amplifies the output of the detecting element 19 for detecting the reflected light of the spot M is therefore a signal which has a drop if the optical disk has a defect or if dust sticks on the surface of the disk. Thus, the defect of the optical disk or the sticking f the dust is detected by using the light beam for erasure, so a defect which becomes a drop-out at the time of the recording is erased while detected, and recording is carried out.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an optical recording/reproducing device that uses a laser beam to record, reproduce, and erase signals in a disc-shaped recording medium (hereinafter referred to as an optical disk) at high density. be.

In particular, it is an object of the present invention to provide an apparatus that prevents errors in recording and reproducing due to defects in optical discs and adhesion of dirt and dust in optical recording and reproducing apparatuses, and performs highly reliable recording and reproducing.

Conventional technology In devices that record and reproduce signals on optical disks by focusing a laser beam into a minute light spot of about 1 μm using a lens, etc., there are cases where there are defects in the recording film of the optical disk, or defects in the substrate on which the recording film is deposited. If there is a large foreign object or if there is still large dirt or dust attached to the surface of the optical disc, a recording or reproduction signal will be lost, causing a dropout of the reproduction signal. In data files, etc., dropouts can cause errors, which can be a serious problem.

For this reason, in the past, optical discs were inspected at the time of shipment by irradiating playback light to detect defective dust-attached areas, and only discs with no major defects were used, or the parts to be recorded were pre-checked using the bli-check method. A method has been used in which defects are inspected using reproduction light, areas with defects are skipped, and only good areas are recorded.

Problems to be Solved by the Invention However, even if a defect-free disk is inspected at the time of shipment and shipped, a problem arises in that dust adheres to the disk and dropout occurs during subsequent use.

Furthermore, the pre-check method has the drawback that the area to be recorded is inspected with a reproduction light, and it takes time to record. The present invention provides a solution to these drawbacks.

Means for Solving the Problems The present invention is an erasure method that uses the thermal energy of a laser beam to change the state of the recording film of an optical disk to a phase transition between an amorphous state and a crystalline state to record, reproduce, and erase signals. The present invention provides a system suitable for a recording/reproducing apparatus using a type of optical disc.

In such a recording/reproducing apparatus, during recording, an erasing beam for erasing a previously recorded signal and a recording/reproducing beam for recording a new signal are irradiated on the same track with a slight interval between them. An override method is used in which data is recorded while being erased. This erase beam is used to detect defects and dust on optical discs.

By using the present invention, it is possible to detect in real time defects in the optical disk and defects that cause recording failures during recording, such as dust adhesion on the surface, and feedback can be immediately provided to the recording, making it possible to perform highly reliable recording.

Embodiment FIG. 1 shows a radial cross-sectional view of an optical disk used in the present invention. The optical disc 1 has a base member 2 made of a transparent material, and the base member 2 has a width W and a depth d.

Grooves with a track pitch P are formed as guide tracks 3 in a spiral shape or a concentric circle shape. Thickness t on top of that
A recording thin film 4 is formed by a method such as vapor deposition, and a protective layer 5 is provided thereon. The guide track 3 has a depth d1 and a width W so that it functions as an optically detectable guide track for the laser irradiation light 6. The guide track 3 allows the irradiation light 6 to record or reproduce a signal along a specific groove.

FIG. 2 shows the configuration of an embodiment of the present invention. In Figure 2, −
The area surrounded by the dotted chain line records and reproduces the signal.

An optical head for erasing is shown. 7 shows a semiconductor laser that generates light with a wavelength λ1, and its output light beam is
Indicated by A condenser lens 8 condenses the divergent output light of the semiconductor laser into a substantially parallel light beam.

9 is a filter that transmits light with wavelength λ1 and reflects light with wavelength λ2, which will be described later; 10 is a filter with wavelength λ1. A polarizing beam splitter effective for light of λ2, 11 a cloudy wave plate for wavelength λ1, and 12 an aperture lens.

The light beam e of the semiconductor laser 7 passes through these optical elements and enters the aperture lens 12. The aperture lens 12 narrows down the incident light beam e to form a substantially circular light spot L on the guide track 3 as shown in FIG.

13 is a semiconductor laser that generates a light beam m having a wavelength λ2, and 14 is a condenser lens.

Reference numeral 16 denotes a % wavelength plate for the wavelength λ2, and the filter 16 has a function of transmitting the light of the wavelength λ1 and reflecting the light of the wavelength λ2. Light beam m emitted from semiconductor laser 13
is reflected by the polarizing beam splinter 1°, and the wavelength plate 1
After passing through the polarization beam splitter 1o, the beam is reflected by the filter 16, passes through the % wave plate 15 again, this time passes through the polarizing beam splitter 1o, passes through the % wavelength plate 11, and enters the aperture lens 12. As shown in FIG. 3, the aperture lens 12 forms an oval optical spot (M) on the guide track 3 which is substantially the same as the optical spora (L), and whose major axis direction coincides with the direction of the guide track. In order to arrange the light spots L and M on the guide track as shown in FIG. This can be achieved by giving it a value.

The oval light spot (M) can be obtained, for example, by reducing the beam width in the track direction of the light beam m incident on the aperture lens 12, or by another method, but the details thereof will be omitted.

The circular first optical spot (L) thus obtained is used for recording or recording/reproduction, and the oval second optical spot M is used for erasing signals.

The reflected light from the optical disk of the light beam e is passed through the aperture lens 1.
2. Wave plate 11. Polarizing beam splitter 1o, y4 wavelength plate 15. The light passes through a filter 16 and is guided to a photodetector 18 via a lens 17 for obtaining control signals for focus and tracking.

The photodetector 18 is configured with a 4-split PIN diode,
From these outputs, a reproduction signal and a control signal for focusing and tracking of the first light spot (L) are obtained using a known method.

On the other hand, the light beam m reflected from the optical disk passes through the aperture lens 12 and the 3A wavelength plate 11. Here, for example, by using a semiconductor laser with a wavelength λ1 of 780 nm and a wavelength λ2 of 830 nm, most of the light transmitted through the % wavelength plate 11 is reflected by the polarizing beam splitter 1° toward the semiconductor laser 7, and is further reflected by the filter 9. The light is reflected by the light receiving element 19 and guided to the light receiving element 19.

The aperture lens is held by an aperture lens drive element 20 so as to be movable in two axes: an optical axis direction for focusing and a direction perpendicular to the track for tracking.

Therefore, the first light spot 7)L and the second light spot M are moved simultaneously and by the same amount in the direction perpendicular to the track by the aperture lens drive element 20. The aperture lens driving element 20 may have a known voice coil type structure, and although the details are omitted, for example, the aperture lens is held by an elastic body and is composed of a focusing coil, a magnetic circuit, a tracking coil, and a magnetic circuit. can be adopted, and focus control corresponding to the surface wobbling of the optical disk of the first light spot L using known technology;
Tracking control for track eccentricity can be performed.

At this time, naturally the second optical spora) M also moves in the same way.

The positional relationship for recording and reproducing signals of the optical spoiler) L and the optical spoiler) M is shown in FIG. 3, with the optical disk being rotated in the direction indicated by the arrow M. Therefore, when recording a signal, the previously recorded signal is first erased using the erasing optical spot V, and a new signal is recorded using the optical spoiler L. At the time of recording, even if no signal is recorded on the optical disc, an optical spoiler (M) for erasing is irradiated.

The light receiving element 19 receives the reflected light from the optical disc M (optical spot).
The signal is detected by the amplifier 21, amplified by the amplifier 21, and then added to the detector 22. The light spot M for erasing is a more elliptical spot than the spot L, but it is a light beam with a partial power for erasing. Therefore, the output of the amplifier 21, which amplifies the output of the detection element 19 that detects the reflected light of the spot (M), becomes a signal whose output drops if there is a defect in the optical disc or dust adhering to the disc surface, as shown in Figure 4B. Become.

The detector 22 is generally composed of a comparator, and compares the output level of the amplifier 21 with the detection level at which dropout occurs during recording, as shown in FIG. Generate a pulse as shown in C. The width of this pulse indicates the size of the defect or dust, and indicates the width at which dropout occurs during recording. The detector 22 may be configured to include a low-pass filter for removing the recorded signal remaining after erasure, high frequency noise, and the like.

Effects of the Invention According to the present invention, since defects and dust adhesion on an optical disk are detected using an erasing light beam, it is possible to perform erasing and recording while detecting defects such as dropouts during recording. If there is a major defect, recording can be immediately stopped and recording can be performed at a location free of defects. In other words, the state of the optical disc at the time of recording is inspected, making it possible to perform an extremely reliable inspection. In addition, since inspection is performed at the same time as recording, highly reliable recording can be performed at high speed without requiring extra time for inspection unlike the Blicheck method.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram showing a part of an optical disk used in an optical recording/reproducing apparatus of the present invention in cross section, FIG. 2 is a principle diagram of an optical recording/reproducing apparatus in an embodiment of the present invention, and FIG. FIG. 4 is a perspective view showing the arrangement of an optical disk and a light spot in the present invention, and is a detection waveform diagram of a portion where there is a defect or adhesion of dust. 7...Semiconductor laser, 8...Condensing lens, 9°16...Filter, 10...
Polarizing beam splitter, 11.15... Wave plate, 12.14.17... Lens, 18...
...Photodetector, 19...Photodetector, 20...
...Lens drive element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4

Claims (1)

[Claims] a first optical spot for recording and reproduction; the first optical spot is located in front of a track formed on the optical disk;
and a means for creating a second light spot for erasing close to the first light spot, a means for detecting light reflected from the optical disk of the second light spot, and a means for detecting the reflected light. 1. An optical recording/reproducing device comprising a detection means for detecting defects on an optical disc, dust adhesion on the surface, etc. based on signals.