US3872241A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video disc pickup with capacitive tracking
Assignee: Zenith Electronics LLC
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Filing: 1973-07-12
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Granted: 1975-03-18
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Expires: 1993-07-12
Abstract
Abstract The electrostatic pick-up system is used for deriving signals which represent video program information stored on a video disc and are suitable for application to a television receiver to reproduce the video program. The pick-up itself has an increased bearing or tracking surface, leading to longer life and may be constructed to track within a single record groove or, alternatively, may bridge across and couple to a series of such grooves for radial tracking while presenting a probe in proper sensing relation to the groove that is to be sensed in any particular revolution of the disc. A generally similar arrangement omits mechanical coupling of the pick-up to the disc and, in its place, uses an electrical system to maintain radial tracking. This last-mentionend embodiment permits both stop frame and slow motion or other variable speed presentation of the image information stored in the disc.
Inventors
- 👤 Robert Adler
- 👤 Roger W Knitter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:19
CPC Classifications
G; G11; G11B; G11B9/00; G11B9/06; G11B9/07; G11B21/00; G11B21/02; G11B21/10; G11B21/106; G11B3/00; G11B3/44; G11B3/46; G11B3/48; G11B9/075
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
264 words
An electrostatic pickup for sensing undulations formed in a pattern of grooves on the surface of a record disc to constitute a spatial representation and storage of the time variations of a signal to be reproduced, which disc further includes a conductive coating, said pickup comprising: a body of insulating material having a bearing or tracking surface with a length much greater than the pitch of the record grooves; a probe of conductive material extending through said body transversely of and intermediate the ends of said bearing surface and projecting into the plane of said bearing surface to sense the groove being tracked, said probe having a dimension measured along the direction of the groove that is small relative to the spatial wavelength of the signal stored on said disc; a first family of capacitive conductive elements supported by said insulating body and extending in the direction of and adapted to overlie one section of said groove patterns; and a second family of capacitive conductive elements also supported by said body and extending in the direction of and adopted to overlie a different section of said groove pattern, each of said capacitive conductive families of conductive elements individually exhibiting, with respect to the disc conductive coating, a capacitance having a predetermined reference value when said probe overlies the middle of a record groove being sensed but, each said family of elements exhibiting a different capacitance of a value which varies in sense and in amount in proportion to the radial displacement of said probe relative to the middle of the record groove being sensed.
Claim 2
Dependent Claim
264 words
An electrostatic pickup for sensing undulations formed in a pattern of grooves on the surface of a record disc to constitute a spatial representation and storage of the time variations of a signal to be reproduced, which disc further includes a conductive coating, said pickup comprising: a body of insulating material having a bearing or tracking surface with a length much greater than the pitch of the record grooves; a probe of conductive material extending through said body transversely of and intermediate the ends of said bearing surface and projecting into the plane of said bearing surface to sense the groove being tracked, said probe having a dimension measured along the direction of the groove that is small relative to the spatial wavelength of the signal stored on said disc; a first family of capacitive conductive elements supported by said insulating body and extending in the direction of and adapted to overlie one section of said groove patterns; and a second family of capacitive conductive elements also supported by said body and extending in the direction of and adopted to overlie a different section of said groove pattern, each of said capacitive conductive families of conductive elements individually exhibiting, with respect to the disc conductive coating, a capacitance having a predetermined reference value when said probe overlies the middle of a record groove being sensed but, each said family of elements exhibiting a different capacitance of a value which varies in sense and in amount in proportion to the radial displacement of said probe relative to the middle of the record groove being sensed.
Claim 3
Dependent Claim
60 words
An electrostatic pickup in accordance with claim 1 in which said body is supported on a tracking arm that comprises a transducer which, in response to an applied potential, deflects said body and said probe radially of the record groove being sensed in an amount and in a direction determined by the amplitude and polarity, respectively, of the applied potential.
Claim 4
Dependent Claim
77 words
An electrostatic pickup system including a pickup in accordance with claim 1 which further includes: means responsive to the capacitance variations of said first and second capacitive conductive elements for developing a control potential representing the sense and the amount of radial displacement of said probe from the middle of the record groove being sensed; and means for applying said potential to said transducer to maintain said probe in the middle of the record groove being sensed.
Claim 5
Dependent Claim
87 words
An electrostatic pickup of the type set forth in claim 1 in which the elements overlying said one section of said groove pattern confront predetermined portions of their underlying grooves while the elements overlying said different section of said groove pattern confront portions of their underlying grooves so that the capacitances exhibited by said first and second families of conductive elements vary in related amounts, but in opposite senses, in response to radial displacement of said probe relative to the middle of the record groove being sensed.
Claim 6
Dependent Claim
38 words
An electrostatic pickup in accordance with claim 1 in which said first family of elements are positioned along one side of said probe and said second family of elements are positioned along the opposite side of said probe.
Claim 7
Dependent Claim
34 words
An electrostatic pickup of the type set forth in claim 5 in which the center-to-center spacing of said elements in each of said families is substantially equal to the pitch of said groove pattern.
Claim 8
Dependent Claim
29 words
An electrostatic pickup in accordance with claim 1 in which conductive elements of each of said families are arranged in an interleaved pattern on each side of said probe.
Claim 9
Dependent Claim
37 words
An electrostatic pickup of the type set forth in claim 7 in which the center-to-center spacing of said elements in each of said families is substantially equal to 1 1/2 times the pitch of said groove pattern.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |