Patent EP0303373A1 successfully refreshed from Google Patents.
EP0303373A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical information recording apparatus provided with means for sampling and holding a servo signal when the intensity of a light beam is varied
Assignee: Canon Inc
•
Filing: 1988-07-28
•
Granted: —
•
Expires: 2008-07-28
Abstract
Abstract An optical information recording apparatus comprises a recording device for condensing into a spot-like shape a light beam intensity-modulated between at least two levels which are not zero, scanning the light beam on a recording medium and recording information thereon, a detector for detecting a signal indicative of the position error between the light beam spot and the medium in the focusing direction perpendicular to the surface of the medium or the tracking direction in a plane parallel to the surface of the medium which is perpendicular to tracks formed on the medium, a servo device for correcting the position error on the basis of the detected signal, means for varying the gain of the servo device in conformity with the intensity level of the light beam, and a device for sampling and holding the detected signal as long as at least the intensity of the light beam is halfway of the shift between different levels.
Inventors
- 👤 Satoshi Shikichi
- 👤 Shigeto Kanda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:25
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0941; G11B7/002; G11B7/0033
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
155 words
An optical information recording apparatus comprising: means for condensing into a spot-like shape a light beam intensity-modulated between at least two levels which are not zero, scanning the light beam on a recording medium and recording information thereon; means for detecting a signal indicative of the position error between said light beam spot and said medium in at least one of the focusing direction perpendicular to the surface of said medium and the tracking direction in a plane parallel to the surface of said medium which is perpendicular to tracks formed on said medium; servo means for correcting said position error on the basis of said detected signal; means for varying the gain of said servo means in accordance with the intensity level of said light beam; and means for sampling and holding said detected signal as long as at least the intensity of said light beam is halfway of the shift between different levels.
Claim 2
Dependent Claim
155 words
An optical information recording apparatus comprising: means for condensing into a spot-like shape a light beam intensity-modulated between at least two levels which are not zero, scanning the light beam on a recording medium and recording information thereon; means for detecting a signal indicative of the position error between said light beam spot and said medium in at least one of the focusing direction perpendicular to the surface of said medium and the tracking direction in a plane parallel to the surface of said medium which is perpendicular to tracks formed on said medium; servo means for correcting said position error on the basis of said detected signal; means for varying the gain of said servo means in accordance with the intensity level of said light beam; and means for sampling and holding said detected signal as long as at least the intensity of said light beam is halfway of the shift between different levels.
Claim 3
Dependent Claim
50 words
An optical information recording apparatus according to Claim 1, wherein said sampling and holding means samples and holds said detected signal before the intensity of the light beam starts the shift to another level, and releases the hold after said shift is terminated and before the next shift is started.
Claim 4
Dependent Claim
32 words
An optical information recording apparatus according to Claim 1, wherein said signal detecting means comprises a photoelectric conversion element which receives the reflected light of the light beam by said recording medium.
Claim 5
Dependent Claim
35 words
An optical information recording apparatus according to Claim 1, wherein said means for varying the gain varies the gain so that the product of the power of said light beam and the gain becomes constant.
Claim 6
Dependent Claim
55 words
An optical information recording apparatus according to Claim 1, wherein said recording means comprises an optical head including a light source and an objective lens for condensing a light beam emitted from said light source, and a motor for moving said recording medium relative to said optical head in the lengthwise direction of the tracks.
Claim 7
Dependent Claim
44 words
An optical information recording apparatus according to Claim 5, wherein said servo means comprises means for driving said objective lens in at least one of the focusing and tracking direction, and an electric circuit for feeding back said detected signal to said driving means.
Claim 8
Dependent Claim
82 words
An optical data storage apparatus comprising an optical head, means for scannning an optical recording medium and the head relative to each other, means for varying an intensity of radiation by the head, a closed loop control system for correcting position error between the head and the recording medium, means for varying the gain of the control system in accordance with the intensity of radiation, and means for holding the correction provided by the control system while the intensity is being varied.
Claim 9
Dependent Claim
82 words
An optical data storage apparatus comprising an optical head, means for scannning an optical recording medium and the head relative to each other, means for varying an intensity of radiation by the head, a closed loop control system for correcting position error between the head and the recording medium, means for varying the gain of the control system in accordance with the intensity of radiation, and means for holding the correction provided by the control system while the intensity is being varied.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.