Apparatus for inhibiting a plurality of disc records from being disposed on a turntable and grounding a disc record disposed on the turntable
US3970317A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1975 |
| Grant date | Jul 20, 1976 |
| Priority date | — |
| Expiry date | Apr 29, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B23/505
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a system for playing back prerecorded signals from a centrally apertured and grooved disc record having an exposed conductive region surrounding the aperture susceptible of accumulating electrical charge of sufficient magnitude to damage a groove-engaging signal pickup for transducing the disc record, an apparatus for inhibiting a plurality of disc records from being disposed on the player turntable while grounding the conductive region of a disc record disposed on the turntable is provided. An engaging member is mounted to a centering spindle secured to the turntable for rotation in a first and a second direction in response, respectively, to the passage of a disc record to-and-from a playback position of the disc record on the turntable. If a disc record is disposed on the turntable, the conductive region of the disc record is located remote from the turntable. When a first disc record is placed on the turntable in the playback position, a conductive portion of the engaging member extends sufficiently to engage the conductive region of the first disc record in order (1) to electrically connect the conductive region which is remote from the turntable to ground potential of the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.