Phonograph record detecting arrangement

Apparatus for use in detecting the presence of a disc record on a turntable, including a source of energy and a detector of the energy, the arrangement being such that a path for the energy is set up between the source and the detector, the path being modified by the presence of a disc record on the turntable, said path having a straight portion lying in the plane of a disc on the turntable.

Apparatus for use in detecting the presence of a disc record on a turntable, including a source of energy and a detector of the energy, the arrangement being such that a path for the energy is set up between the source and the detector, that the path is modified by the presence of a disc record on the turntable, wherein the turntable defines a hole so arranged that the association of energy intercepting means with the hole can be used to modify the said energy path according to whether or not a disc is present on the turntable, said source and the detector both being located on the side of the plane in which the turntable lies opposite to that on which a record is located and a disc record, when present on the turntable, provides the energy intercepting means and causes a reflectivity to be presented to energy from the source passing through the hole which is different from that presented by the turntable.

Apparatus for use in detecting the presence of a disc record on a turntable, including a source of energy and a detector of the energy, the arrangement being such that a path for the energy is set up between the source and the detector, the path being modified by the presence of a disc record on the turntable, the turntable defining a hole so arranged that the association of energy intercepting means with the hole can be used to modify the said energy path according to whether or not a disc is present on the turntable, said turntable defining a plurality of the said holes, each at a different distance from the centre of the turntable, a respective associated means is provided in each hole for use in detecting a different size of disc record, and an insert having an energy reflecting wall in a hole.

Apparatus for use in detecting the presence of a disc record on a turntable, including a source of energy and a detector of the energy, the arrangement being such that a path for the energy is set up between the source and the detector, the path being modified by the presence of a disc record on the turntable, the turntable defining a hole so arranged that the association of energy intercepting means with the hole can be used to modify the said energy path according to whether or not a disc is present on the turntable, said hole defined by the turntable being a radially extending slot in the surface of the turntable, including detector means to detect the length of the said slot which is covered when a disc record is present on the turntable, thereby to enable a measure of the diameter of the record to be provided.

Apparatus for use in detecting the presence of a disc record on a turntable, including a source of energy and a detector of the energy, the arrangement being such that a path for the energy is set up between the source and the detector, the path being modified by the presence of a disc record on the turntable, and means for labelling the energy from the source whereby stray or ambient energy of the same type can be discriminated against.