Patent
Automatic focusing device
Tsuneshi Yokota
- 14 Jun 1982
17
TL;DR: In this article, an automatic focusing device includes an optical head which comprises a focusing lens system and an optical sensor, which is driven to focus a reading laser beam or a recording laser beam on an optical disk.
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Abstract: An automatic focusing device includes an optical head which comprises a focusing lens system and an optical sensor. The focusing lens system focuses a reading laser beam or a recording laser beam on an optical disk. The optical sensor generates photoelectric signals which correspond to the sections of a beam spot formed by a laser beam reflected from the optical disk. Record signal components corresponding to a recording laser beam are removed from the photoelectric signals by switch circuits. The photoelectric signals no longer containing record signal components are supplied to envelope detectors. The envelope detectors generate envelope signals each formed of signal components which correspond to a laser beam reflected from the surface of the optical disk. According to the difference between the envelope signals the focusing lens system is driven to thereby focus a laser beam on the optical disk.
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Citations
Patent
Optical disc players
Hajime Yano
- 09 Feb 1984
TL;DR: In this paper, an optical disc player is used to cause a light beam to impinge through an object lens on a recording surface of a record disc and to receive a reflected light beam passing through the object lens from the recording surface by photodetecting means.
28
Patent
Automatic focusing system with dual diffraction gratings and converging means
Hamada Akiyoshi,Mitsutoshi Yagoto,Murakami Masanori +2 more
- 31 Jul 1989
TL;DR: In this paper, an automatic focusing system for forcusing on an optical disk, the system including a laser beam source, an objective lens, a photodetector for detecting a focusing error, a beam splitter disposed between the beam source and the objective lens and a pair of diffraction gratings disposed by the laser source to form a moire pattern on the photodeter means is presented.
16
Patent
Focus adjustment system for optical disk apparatus
Masahiro Takahashi
- 02 Aug 1990
TL;DR: A focus adjustment system for an optical disk apparatus has a monitor detector that detects the power of a light beam emitted from a laser, and a peak detector produces a peak-detect signal when peak beam power is detected as mentioned in this paper.
16
Patent
Magneto-optic read-out method and apparatus with polarization correction means
Joseph F. Revelli,Douglas G. Stinson,Stuart D. Perry +2 more
- 17 Feb 1987
TL;DR: In this article, an improved method and apparatus for optically reading pre-recorded magnetic information on a magneto-optic recording element is presented. But the authors focus on the problem of minimizing the adverse effect of unpredictable variations in the state of polarization of the beam of radiation used for read-out.
16
Patent
Method and apparatus for optical recording and reproduction with tracking servo reducing track offset
Toshimitsu Kaku,Kazuo Shigematsu,Hisataka Sugiyama,Takeshi Maeda,Masahiro Takasago +4 more
- 11 Aug 1988
TL;DR: In this paper, an optical recording and reproducing apparaus comprising a light source directing a light spot toward a recording medium, a detection system detecting light reflected from the recording medium to derive an electrical signal from the reflected light, an information processing circuit modulating the intensity of the light spot according to writing pulses, and a tracking servo circuit carrying out servo operation on the basis of the electrical signal and including an extracting circuit connected to a source of extracting pulses having a pulse width at least equal to the writing pulse width.
11
References
Patent
Optical focussing device
Claude Bricot,Jean Claude Lehureau +1 more
- 07 May 1976
TL;DR: In this article, a cylindrical lens is arranged in the path of a light beam reflected by the data carrier and arranged in such a way that the light spot obtained there, normally substantially circular in shape, is distorted by elongation if focussing of the read-out beam on the carrier is incorrect.
77
Patent
Focus control system for optical read-out apparatus
Yoshihiro Utsumi
- 12 Mar 1979
TL;DR: In this paper, a focus control circuit produces an output signal corresponding to the phase relationship of the outputs from the photodetector elements, for delivery to a drive coil capable of electromagnetically moving the objective toward and away from the record disc for readjustment of the distance therebetween.
31
Patent
Optical scanning apparatus with focussing system
Bierhoff Martinus Petrus Maria,Immink Kornelis Antonie +1 more
- 13 Jun 1980
TL;DR: In this article, a phase detector is used to detect an incorrect control point of a focussing system and a correction signal is generated by the phase detector to correct the error.
26
Patent
Controlled system for focussing a read-out light beam
Claude Tinet
- 14 Nov 1974
TL;DR: In this article, a controlled system for focussing a read-out light beam onto a moving track carrying information, comprising a focussed objective lens for forming a periodic motion along its optical axis, under the action of a pilot device, is presented.
24
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