US3654401A
Expired / Lapsed
US
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Playback system with radiation guide member having a slide portion extending into the groove
Assignee: Licentia Patent Verwaltungs GmbH
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Filing: 1970-05-28
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Granted: 1972-04-04
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Expires: 1990-05-28
Abstract
Abstract An improved system for reproducing signals stored on a recording medium in the form of undulations corresponding to the signals, the undulations generally being formed as a spiral groove. The undulations on the recording medium are moved past a suitable radiation source, such as a light source, and the density of the radiation emanating from the undulations, which is a function of the curvature of the undulation, is detected by a suitable radiation detecting means after it passes through a suitable slit aperture arranged at a predetermined distance from the recording medium surface so that variations in the density are a function of the undulations. The undulations may be either frequency or phase modulated with respect to the signal and their amplitude can be modified as a function of their recorded wavelength in such a manner that the curved surface portions of the undulations have nearly the same focal length for all occurring wavelengths. The tracking of the playback system is improved by providing a radiation guide member which slides along the raised portions of the surface of the recording medium and has a slide member which extends into the particular groove or portion thereof being scanned. Formed within the guide member is an element which is optically effective for the type of radiation utilized to collect the emanating radiation and aids in its evaluation. This element may be either the slit aperture itself or a collecting lens which directs the emanating radiation to the slit aperture.
Inventors
- 👤 Gerhard Dickopp
- 👤 Helmut Batsch
- 👤 Eduard Schuller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:07
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
265 words
In a system for playing back, by means of a beam of parallel light radiation, signals recorded in the form of a carrier frequency which is frequency or phase modulated with the signals and within a groove or grooves on the surface of a recording medium by means of undulations of said surface corresponding to the time sequence of the signal values, wherein said record medium is moved relative to said beam of light radiation and wherein a slit aperture and said surface bearing the undulations are disposed In the path of said beam of radiation at such a distance from one another that a change in the density of the radiation emanating from the surface bearing the deformations results in the plane of the slit aperture, said change in density being dependent on the undulations existing on said surface in the direction of the relative movement of the recording medium and said reading beam and which change in density at least qualitatively reproduces the course of the undulations, and wherein means are provided behind said slit aperture for detecting the radiation passing through said slit aperture; the improvement comprising: radiation guide means positioned in the path of said beam of said radiation, said guide means including a slide member which extends into the particular groove or portion thereof on said surface of said record medium from which it is desired to play back the recorded signal, said guide means including means optically effective for the type of radiation employed for aiding in the evaluation of the light density fluctuations produced in said particular groove.
Claim 2
Dependent Claim
265 words
In a system for playing back, by means of a beam of parallel light radiation, signals recorded in the form of a carrier frequency which is frequency or phase modulated with the signals and within a groove or grooves on the surface of a recording medium by means of undulations of said surface corresponding to the time sequence of the signal values, wherein said record medium is moved relative to said beam of light radiation and wherein a slit aperture and said surface bearing the undulations are disposed In the path of said beam of radiation at such a distance from one another that a change in the density of the radiation emanating from the surface bearing the deformations results in the plane of the slit aperture, said change in density being dependent on the undulations existing on said surface in the direction of the relative movement of the recording medium and said reading beam and which change in density at least qualitatively reproduces the course of the undulations, and wherein means are provided behind said slit aperture for detecting the radiation passing through said slit aperture; the improvement comprising: radiation guide means positioned in the path of said beam of said radiation, said guide means including a slide member which extends into the particular groove or portion thereof on said surface of said record medium from which it is desired to play back the recorded signal, said guide means including means optically effective for the type of radiation employed for aiding in the evaluation of the light density fluctuations produced in said particular groove.
Claim 3
Dependent Claim
23 words
The playback system as defined in claim 1 wherein said optically effective means is said slit aperture which extends through said guide means.
Claim 4
Dependent Claim
59 words
The playback system as defined in claim 1 wherein said optically effective means is a lens arrangement which reproduces the plane of evaluatable primary light density variations directly produced by the undulations in a second plane bearing corresponding secondary light density variations, whereby said secondary light density variations can then pass through said slit aperture to said detecting means.
Claim 5
Dependent Claim
27 words
The playback system as defined in claim 1 wherein the sides of said guide means which are adjacent the neighboring grooves are provided with a radiation-impermeable coating.
Claim 6
Dependent Claim
65 words
The playback as defined in claim 1 wherein said guide means is provided with laterally extending surfaces for contacting the raised portions of said surface forming the walls between adjacent grooves, and wherein said slide member engages the groove profile with lateral play and extends into said groove to such a distance that the base thereof does not touch the groove bottom bearing the undulations.
Claim 7
Dependent Claim
80 words
The playback system as defined in claim 5 wherein said optically effective means is a slit aperture which is constructed to be clearly permeable for the type of radiation employed and comprises two parallel bordering surfaces which are disposed perpendicular to the direction of relative movement between said guide means and the surface of the groove being scanned, said bordering surfaces being portions of said guide means, and being substantially centrally located between the peripheral surfaces of said guide means.
Claim 8
Dependent Claim
26 words
The playback system as defined in claim 6 wherein said slit aperture takes up a central spatial portion within the outline surfaces of said guide means.
Claim 9
Dependent Claim
120 words
The playback system as defined in claim 7 wherein an objective lens is provided in the path of said reading beam of radiation between the outlet of said slit aperture and said detecting means for producing an intermediate reproduction of the slit aperture outlet, the aperture of said objective lens being so dimensioned that when a slit aperture with well reflecting bordering planes is used the outer beams of the reading beam bundle of rays which exit under acute angles with respect to the optical axis of the reading beam bundle are covered over the entire permissible fluctuation range of the position of the guide element with respect to the groove being scanned in both the axial and radial directions.
Claim 10
Dependent Claim
42 words
The playback system as defined in claim 6 wherein the length of said slit aperture is not larger than one-half of the shortest recorded wavelength, wherein the width of said slit aperture is approximately equal to the width of the recorded undulations.
Claim 11
Dependent Claim
35 words
The playback system as defined in claim 9 wherein the depth of said slit aperture is substantially greater than the length thereof and wheRein said bordering surfaces of said slit aperture have good reflecting properties.
Claim 12
Dependent Claim
36 words
The playback system as defined in claim 6 wherein said slit aperture is filled with a solid transparent material which is permanently connected to said bordering surfaces and with the adjacent portions of the guide means.
Claim 13
Dependent Claim
41 words
The playback system as defined in claim 11 wherein said transparent material has an index of refraction such that total reflection results along said bordering surfaces in the usable range of the optical impingement angles occurring at the slit aperture entrance.
Claim 14
Dependent Claim
80 words
The playback system as defined in claim 5 wherein said optically effective means is a lens arrangement which reproduces the plane of evaluatable primary light density variations directly produced by the undulations in a second plane bearing corresponding secondary light density variations, whereby said secondary light density variations can then pass through said slit aperture to said detecting means, and wherein said lens arrangement contains a condensor lens whose image length is selected to be greater than the object length.
Claim 15
Dependent Claim
41 words
The playback system as defined in claim 13 wherein at least the portion of said guide means which is disposed in the path of said beam portion to be evaluated consists of a material which is clearly permeable for the radiation.
Claim 16
Dependent Claim
15 words
The playback system as defined in claim 14 wherein said lens is a cylindrical lens.
Claim 17
Dependent Claim
57 words
They playback system as defined in claim 14 wherein the clearly permeable portion of said guide means bears a collector lens on its side facing away from said record medium, with the axis of said lens being perpendicular to the direction of relative movement of said guide means with respect to the undulation-bearing groove surface being scanned.
Claim 18
Dependent Claim
54 words
The playback system as defined in claim 16 wherein the length of said slit aperture is at least approximately equal to one-half of the shortest recording wavelength contained in the undulations, multiplied by the enlargement factor between said plane of the primary light density variations and said plane of the secondary light density variations.
Claim 19
Dependent Claim
34 words
The playback system as defined in claim 17 wherein the width of said slit aperture is substantially larger than the width of the light track in said plane of the secondary light density changes.
Claim 20
Dependent Claim
19 words
The playback system as defined in claim 18 wherein said detecting means is mechanically connected with said slit aperture.
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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) | 1975-04-04 | 1975-10-04 | 1976-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-04 | 1979-10-04 | 1980-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-04 | 1983-10-04 | 1984-04-04 | $7700.00 | Window Closed / Lapsed |