Optical recording and reproducing apparatus, tilt correction method, tilt correction program and medium
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHideki Aikoh, Tohru Nakamura
Life of this patent
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Abstract
Tilt correction means is operated so that the degree of modulation represented by the ratio of the amount of the detected reflected light from the groove areas G and the amount of the detected reflected light from the flat land areas L becomes maximal in a state wherein focus servo-control is made effective. Hence, the present invention can provide a system applicable to all optical disks including recording types and reproduction-only types, and capable of detecting a tilt correction signal without providing any special countermeasures on optical disks and devices, whereby it is possible to obtain an optical recording apparatus not adversely affecting the usage feeling of a user.
Claims22
An optical recording and reproducing apparatus for optically recording and reproducing information, comprising:
- an optical head having (1) means of condensing light into a medium provided with first areas having dent portions or groove portions and substantially flat second areas, and (2) means of detecting signals from said medium, and
- tilt correction means of correcting the relative angle between said medium and the axis of light outgoing from said condensing means of said optical head, wherein
- while said medium is subjected to focus servo-control by using a light spot formed by said condensing means, said tilt correction means is operated so that a value based on the difference between the detection level of the reflected light in said first areas and the detection level of the reflected light in said second areas among the detection levels of light reflected by said medium and received and detected by said signal detection means becomes virtually maximal, thereby to correct said relative angle.
An optical recording and reproducing apparatus for optically recording and reproducing information, comprising:
- an optical head having (1) means of condensing light into a medium having tracks wherein pit rows or groove areas, and flat land areas formed alternately on a plane, and (2) means of detecting signals from said medium, and
- tilt correction means of correcting the relative angle between said medium and the axis of outgoing light from said condensing means of said optical head, wherein
- while said medium is subjected to focus servo-control by using a light spot formed by said condensing means, and when said signal detection means receives and detects the reflected light from said medium owing to said light spot, said tilt correction means is operated so that a value obtained by the following equation:
- |level L−level G|/|level L+level G| [Equation 2]
- in the relationship between the level (level G) of the reflected light in said pit rows or said groove areas and the level (level L) of the reflected light in said flat land areas, becomes virtually maximal, thereby to correct said relative angle.
An optical recording and reproducing apparatus for optically recording and reproducing information, comprising:
- an optical head having (1) means of condensing light into a medium wherein flat land areas and sample pit areas for detecting a tracking error signal by the sample servo-control method are formed on a plane, and (2) means of detecting signals from said medium, and
- tilt correction means of correcting the relative angle between said medium and the axis of outgoing light from said condensing means of said optical head, wherein
- while said medium is subjected to focus servo-control by using a light spot formed by said condensing means, and when said signal detection means receives and detects the reflected light from said medium owing to said light spot, said tilt correction means is operated so that a value obtained by the following equation:
- |level L−level S|/|level L+level S| [Equation 3]
- in the relationship between the level (level S) of the reflected light in said sample pit areas and the level (level L) of the reflected light in said flat land areas, becomes virtually maximal, thereby to correct said relative angle.
A tilt correction method for correcting the relative angle between a medium and the axis of outgoing light from condensing means in an optical recording and reproducing apparatus for optically recording and reproducing information, comprising an optical head having (1) said condensing means of condensing light into said medium provided with first areas having dent portions or groove portions and substantially flat second areas, and (2) means of detecting signals from said medium, wherein
- while said medium is subjected to focus servo-control by using a light spot formed by said condensing means, said relative angle is corrected so that a value based on the difference between the detection level of the reflected light in said first areas and the detection level of the reflected light in said second areas among the detection levels of light reflected by said medium and received and detected by said signal detection means becomes virtually maximal.
In an optical recording and reproducing apparatus focusing a light beam on an information medium having grooved portions and flat portions, the grooved portions interleaved with the flat portions,
- a method of correcting a relative angle between the light beam and the information medium comprising the steps of:
- (a) focusing the light beam on first areas having grooved portions and second areas having flat portions;
- (b) measuring intensity level of light reflected from the first areas and intensity level of light reflected from the second areas;
- (c) differencing the intensity levels of light measured in step (b) to obtain a first signal level;
- (d) repeating steps (a), (b) and (c) on other first and second areas to obtain a second signal level;
- and
- (e) correcting the relative angle between the light beam and the information medium based on a difference between the first signal level and the second signal level.
Dependencies are inferred from the claim text.