Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2000-08-01
2002-09-10
Tran, Thang V. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S053370, C369S044270
Reexamination Certificate
active
06449232
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for use in an apparatus for recording and reproducing a reproduction-only optical disk and a recording/reproducing optical disk.
BACKGROUND ART
An apparatus for recording and reproducing information onto/from a disk, such as, typically, DVD-RAM driving apparatuses, needs to be compatible with a plurality of types of disks having different substrate thicknesses, track patches or recording densities, and the like. Accordingly, the apparatus should determine the type of a disk loaded in the recording/reproducing apparatus and transition to a state of the apparatus suitable for the disk.
To determine the type of a disk, the control circuit or the signal processing circuit is operated in an approximate manner to reproduce an address signal recorded on the disk, or to search a region called table of Contents (TOC) or a region called control track into which information on the number of signal recording surfaces, pit density, track pitch, or the like is recorded for reproduction of the information therein. U.S. Pat. No. 5,587,981 discloses such a method for determining the type of a disk.
However, there is a problem in that conventional recording/reproducing apparatuses cannot always reproduce information recorded on the loaded disk. There is also a problem in that it takes a long time to determine the type of the loaded disk.
In view of the above-described problems, an object of the present invention is to provide a method for determining the types of a plurality of disks, whereby a single apparatus can record and reproduce disks compliant with different standards.
DISCLOSURE OF THE INVENTION
A method according to the present invention for determining the type of a disk, includes a first step of determining a substrate thickness of the disk based on a focusing error signal representing a positional deviation of the focal point of a light beam from a recording surface of the disk, when a focusing section for bringing the light beam into a focus on the disk is moved in such a way as to approach or withdraw from the recording surface of the disk; a second step of determining the number of recording surfaces of the disk when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk and a third step of determining whether or not the disk can be recorded and reproduced using a tracking error signal representing a positional deviation of the focal point of a light beam from a track of the disk, when the light beam crosses the track,
wherein at least one of the second step and the third step is performed after the first step is performed, thereby attaining the above-described object.
The focusing section may include a plurality of focusing characteristics; and in the first step, the substrate thickness of the disk may be determined based on the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk while the focusing characteristics of the focusing section are switched.
The focusing section may include a plurality of objective lenses having different focusing characteristics; and in the first step, the substrate thickness of the disk may be determined based on the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk while the objective lenses are switched.
In the first step, the substrate thickness of the disk may be determined based on the amplitude of the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk.
In the first step, the substrate thickness of the disk may be determined based on a signal obtained by synthesizing the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk with at least part of one of reflected or transmitted light from the disk.
In the first step, the substrate thickness of the disk may be determined based on the amplitude of a signal obtained by synthesizing the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk with at least part of one of reflected or transmitted light from the disk.
In the second step, the substrate thickness of the disk may be determined based on the number of detections of a predetermined waveform in the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk.
In the second step, the substrate thickness of the disk may be determined based on the number of detections of in-focus positions in the focusing error signal when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk.
In the second step, the substrate thickness of the disk may be determined based on the number of detections of a change from an intermediate value to a bottom value and a change from the bottom value to the intermediate value of the focusing error signal, in a predetermined order, when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk.
A change from an intermediate value to a peak value of the focusing error signal may be detected by comparing the focusing error signal with a first reference value; a change from the peak value to the intermediate value of the focusing error signal may be detected by comparing the focusing error signal with a second reference value; the first reference value may be defined to be larger than the intermediate value of the focusing error signal; and the second reference value may be defined to be smaller than the intermediate value of the focusing error signal.
The second step may include the steps of: determining one of a first internal state or a second internal state based on a position, on which the light beam is brought into a focus, when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk; and calculating by adding or subtracting a predetermined value based on the determined internal state and the focusing error signal, wherein the internal state determining step and the calculating step may be repeated in at least a part of an interval where the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk; and the number of recording surfaces of the disk is determined based on the result of the calculation.
The first internal state may be where the focal point of the light beam is in focus; and the second internal state may be where the focal point of the light beam is out of focus.
The focusing position of the light beam may be detected based on an order in which the focusing error signal transitions at least one of a first reference value, a second reference value, a third reference value, and a fourth reference value when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk.
The focusing section may be moved in such a way as to approach or withdraw from the recording surface of the disk, the internal state determining step determines that the internal state transitions to the first or second state in the case of detecting any one of transition from the first reference value to the second reference value or transition from the fourth reference value to the third reference value.
In the calculating step: the predetermined value may be added when the focusing error signal transitions from the fourth reference value to the third reference value, in the second internal state; the predetermined value may be added when the focusing error signal transitions from the first reference value to the second reference value, in the first internal state; the predetermined value may be subtracted when the focusing error signal transitions from the fourth reference value to the th
Kuwahara Masaya
Maruyama Masuo
Mohri Masanari
Nishihara Yasuo
Sakaguchi Akihiro
Matsushita Electric - Industrial Co., Ltd.
Renner Otto Boisselle & Sklar
Tran Thang V.
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