| 摘要 |
A method and apparatus employing optical type techniques are provided for use in reliably sensing the juxtapositional relationship between successively relevant portions of an object and a sensing unit that are relatively movable, in accurately maintaining a predetermined juxtapositional relationship between such portions of the object and the sensing unit during relative movement therebetween, and, when appropriate to the application, in also faithfully sensing other information carried by such portions of the object. The method and apparatus are characterized by eliminating any need for mechanical engagement between the sensing unit and the portions of the object to which the sensing unit responds and by utilizing only optical type coupling between such portions of the object and the sensing unit for the transfer of all information to be acquired by the sensing unit from the object. An important and currently preferred application of the method and apparatus, in which both positional and other information are sensed, is in playing ordinary phonograph records without inducing wear thereto in the course of sensing the recorded information. In the context of the mentioned application, both information for controlling the juxtapositional relationships between the record and the sensing unit with respect to both spacing and groove tracking and information with respect to the recorded audio material are sensed. In other contemplated applications, the sensing of only that information needed for controlling juxtapositional relationships may be desired, or the other information to be sensed may represent digitally encoded data, etc.
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