US4499572A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reading information or defect out of rotating disc
Assignee: Olympus Corp
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Filing: 1982-07-26
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Granted: 1985-02-12
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Expires: 2002-07-26
Abstract
Abstract In order to read out information recorded on a disc rotating at a constant angular velocity by means of a pick-up head movably arranged in a disc radius direction, a head position on the disc is detected to obtain a position signal representing a distance from a disc center to the pick-up head, and then a pulse signal having a frequency corresponding to the position signal thus obtained is generated. A detection signal supplied from the pick-up head and the pulse signal are supplied to an AND gate and pulses of the gated out pulse signal are counted by a counter. The number of the counted pulses represents correctly a length of the information recorded on the disc irrespective of position of the information on the disc.
Inventors
- 👤 Shozi Yoshikawa
- 👤 Masaharu Sakamoto
- 👤 Hiroshi Kodama
- 👤 Kunio Yamamiya
- 👤 Kiichi Kato
- 👤 Ken Ohsima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:36
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/36; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/95; G01N21/9506; G11B20/00; G11B20/02; G11B20/08; G11B20/10; G11B7/00; G11B7/002; G11B7/0037; G11B7/00375; G11B7/007; G11B7/013
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
119 words
A method of detecting information or defects out of a disc by rotating the disc at a constant angular velocity with respect to a pick-up head which is moved in a radial direction of the disc and scans the disc along spiral or concentric tracks to produce a detection signal, comprising the steps of detecting a position of the pick-up head above the disc to produce a position signal; generating in response to said position signal a pulse signal having a frequency which is proportional to a distance from a center of the disc to the pick-up head; and deriving an output signal from the detection signal supplied from the pick-up head under the control of said pulse signal.
Claim 2
Independent Claim
119 words
A method of detecting information or defects out of a disc by rotating the disc at a constant angular velocity with respect to a pick-up head which is moved in a radial direction of the disc and scans the disc along spiral or concentric tracks to produce a detection signal, comprising the steps of detecting a position of the pick-up head above the disc to produce a position signal; generating in response to said position signal a pulse signal having a frequency which is proportional to a distance from a center of the disc to the pick-up head; and deriving an output signal from the detection signal supplied from the pick-up head under the control of said pulse signal.
Claim 3
Dependent Claim
57 words
A method according to claim 1, wherein said output signal deriving step comprises a step of gating the pulse signal by means of the detection signal, and a step of counting by a counter the number of gated out pulses to derive the output signal having a numeral value representing a length of detected information or defect.
Claim 4
Dependent Claim
36 words
A method according to claim 1, wherein said output signal deriving step comprises a step of storing serially the detection signal in a shift register, while the pulse signal is used as a shift clock pulse.
Claim 5
Dependent Claim
19 words
A method according to claim 3, wherein said detection signal stored in the shift register is read out parallelly.
Claim 6
Dependent Claim
59 words
A method according to claim 1, wherein said step of detecting the position of the pick-up head comprises a step of generating a voltage having an amplitude which corresponds to the pick-up head position, and said pulse signal generating step comprises a step of generating said pulse signal from a voltage controlled oscillator which is controlled by said voltage.
Claim 7
Dependent Claim
40 words
A method according to claim 5, wherein the amplitude of said voltage is directly proportional to the distance between the pick-up head and the disc center and said frequency of the pulse signal is also directly proportional to said voltage.
Claim 8
Dependent Claim
23 words
A method according to claim 6, wherein said voltage is derived from a potentiometer whose variable arm is coupled with said pick-up head.
Claim 9
Dependent Claim
29 words
A method according to claim 2, wherein said counter is preset by an edge signal which is derived from the detection signal and is delayed by a short time.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |