Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1984-06-28
1987-11-10
Wan, Gene
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250204, G01J 136
Patent
active
047059419
ABSTRACT:
In an apparatus for detecting a focusing state of an optical system, a laser beam generated from a laser unit is transmitted through a beam splitter to a convergent lens. The laser beam is converged by the convergent lens and projected toward the surface of an optical disk. The laser beam reflected from the disk surface is reflected by the beam splitter and projected through the aperture of a light shielding plate to a photodetector. The photodetector has first and second photo sensitive regions arranged concentrically, and when the convergent lens is in a focusing state, the levels of the first and second photo signals from the first and second photo sensitive regions are equal to one another, and the output signal from the differential amplifier is maintained at zero level. When the convergent lens is approaches the focusing state from the position sufficiently separated from the optical disk, a positive output signal is generated from the differential amplifier. When the convergent lens gradually approaches from the position of the focusing state to the optical disk, the beam spot gradually becomes small on the photosensitive regions and again starts expanding, but the laser beam does not expand beyond a predetermined beam diameter on the photosensitive regions due to the light shielding plate. Therefore, the beam is retained at a predetermined value. Consequently, the output signal from the differential amplifier is not varied from the negative level to the positive level.
REFERENCES:
patent: 4370551 (1983-01-01), Fukuhara et al.
patent: 4521680 (1985-06-01), Ando
Patent Abstracts of Japan, vol. 8, No. 97, May 8th, 1984, p. (P-272) (1534); and JP-A-59-8146 (Ricoh) 17-01-1984.
Patent Abstracts of Japan, vol. 4, No. 184, Dec. 18th, 1980, p. (P-41) (666); and JP-A.55-125547 (Matsushita) 27-09-1980.
Ohgoshi Seiichi
Yamada Hisashi
Kabushiki Kaisha Toshiba
Wan Gene
LandOfFree
Apparatus for detecting a focusing state of an optical system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for detecting a focusing state of an optical system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for detecting a focusing state of an optical system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1069474