Apparatus for a record player distinguishing between recorded and unrecorded portions of a disc
US4707815A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1980 |
| Grant date | Nov 17, 1987 |
| Priority date | — |
| Expiry date | Aug 25, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B3/0957
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An unrecorded portion detecting apparatus for a record player. The apparatus has a device such as light-emitting diode for applying light to disc surface and a pair of light-sensitive devices such as phototransistors for sensing light reflected by the disc surface mounted on the tone arm. The pair of light-sensitive devices are separated from each other along a tracing line of the tone arm. The apparatus further has a circuit for producing a detecting signal at the time when the tone arm detects the unrecorded portion, resulting in an output signal from the leading device of the pair of light-sensitive devices. The circuit includes means for uniforming levels of the output signals of the pair of the light-sensitive devices under the same condition, means for differentiating the uniformed signals by a predetermined extent and means for comparing level relationship between the output signals. When the tone arm traces above a boundary when a recorded portion and an unrecorded portion adjoin each other, the level states of the devices as to sensing or not sensing a predetermined level of light are reversed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.