Optical disk device

An optical disc device, optical disc technology, applied in optical recording head, head configuration/installation, recording/reproducing by optical method, etc., can solve the problems of deviation, tracking disturbance, tracking error signal disturbance, etc.

Inactive Publication Date: 2006-05-03
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, when there is a scratch on the surface of the optical disc, foreign matter is attached, or the recorded pit is damaged (this situation is called a defect), when the light beam enters the defective part, the defect will cause a large impact on the tracking error. Signal interference causes the tracking of the beam to change. When the beam leaves the defect part, the tracking will be disturbed or deviated

Method used

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no. 1 Embodiment approach

[0062] figure 1 An optical disc device according to the first embodiment of the present invention is shown.

[0063] exist figure 1 In the optical disc device shown, 1 is an optical pickup, 8 is an optical disc, 2 is a first output terminal for obtaining the return light of the preceding sub-beam, 3 is a second output terminal for obtaining the return light of the subsequent sub-beam, and 9 is for obtaining the return light of the main beam The 3rd output terminal, 4 is TE signal generating circuit (tracking error signal generating device), 6 is tracking control circuit (tracking control device), 7 is servo holding circuit (holding device), 10 is AGC circuit (AGC device), 11 is a focus control circuit (focus control means), and 39 is an AGC hold circuit (AGC hold means). The above structure, and the already described Figure 14 The optical disc device is the same, so its detailed description is omitted.

[0064] As shown in the first technical solution, the present invent...

no. 2 Embodiment approach

[0077] Figure 4 An optical disc device in the second embodiment of the present invention is shown. right with figure 1 The same symbols are attached to the same parts, and the description thereof will be omitted.

[0078] The optical disc device of this embodiment and figure 1 The difference of the first embodiment shown in the above is that the defect period detection circuit 5 is connected not only to the first output terminal 2 that outputs the E signal but also to the second output terminal 3 that outputs the F signal. Thus, the defect period can be detected by using the E signal that enters the defect period earlier than the main beam and the F signal that exits the defect period later than the main beam, thereby suppressing the amplitude of the tracking error signal when the tracking servo is maintained. It is possible to accurately detect the drop-out from the defect period, so it is possible to provide an optical disc device with little disturbance to the trackin...

no. 3 Embodiment approach

[0094] Hereinafter, an optical disc device according to a third embodiment will be described. This embodiment shows a further embodiment of the defect period detection circuit.

[0095] Figure 7 The structure of the defect period detection circuit of this embodiment is shown (sixth claim). right with Figure 5 The same symbols are attached to the same parts, and the description thereof will be omitted. and Figure 5 The difference is that a peak hold circuit and a valley hold circuit are connected between the E signal and F signal and the binarization circuit (pulse generation circuit), and a peak hold circuit and the output of the binarization circuit are connected between the above peak hold circuit and the output of the binarization circuit. Variable descent rate circuit.

[0096] Hereinafter, a detailed structure will be described. However, the structure related to the generation of the 3rd and 6th reference levels is related to the Figure 5 exactly the same and o...

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Abstract

The present invention provides an optical disc device capable of limiting disturbance to tracking control to a small amount even when there is a defective portion such as a scratch generated in the manufacturing process of the disc on the recording surface. The output terminal (2) is connected to the optical pickup (1), and outputs the return optical signal of the preceding sub-beam obtained by converting the return light of the preceding sub-beam before the main beam into an electrical signal. A defect period detection circuit (5) detects a defect period during a beam passing through a defect portion of an optical disc (8) based on a preceding sub-beam return light signal from the output terminal (2). The servo hold circuit (7) holds the tracking servo during the detected defect period. Therefore, even if the amplitude of the RF signal rapidly attenuates during the defect period, the defect period can be detected at an early stage of its attenuation, and the variation in the amplitude of the tracking error signal can be suppressed to be small.

Description

technical field [0001] The present invention relates to a 3-beam type optical disc device for reproducing and outputting information recorded on an optical disc. Background technique [0002] Generally speaking, in an optical disc device that reproduces an optical disc such as a CD (Compact Disk) or a DVD (Digital Versatile Disk), it is used to make the read light spot of the light beam from the optical pickup follow the pit on the optical disc. Tracking control (tracking servo) of the track of the string is essential. This tracking servo is performed by generating a tracking error signal based on a signal of return light (reflected light) from the optical disc detected by the optical pickup, and based on the tracking error signal. [0003] However, when there is a scratch on the surface of the optical disc, foreign matter is attached, or the recorded pit is damaged (this situation is called a defect), when the light beam enters the defective part, the defect will cause a l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/00G11B7/09G11B7/12G11B20/18
CPCG11B7/0948
Inventor 越田浩旨春井正德中田康夫坂善光金野耕寿片田真三康
Owner PANASONIC CORP
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