Abstract: A sync signal detection apparatus is provided wherein a sync signal represents the top of recorded data. The sync signal includes a plurality of marks each having a different pattern from the pattern of any other mark. The apparatus is equipped with a circuit for sequentially detecting the patterns of the individual marks in a reproduction mode. Also, a circuit is provided generating a sync pulse at the top of the data in accordance with the address pattern of the mark after a predetermined number of marks are detected. The apparatus ensures accurate reproduction of the recorded data with a small number of bits and an increase in data reliability.

Abstract: An optical disc apparatus provided with a recording correcting system for controlling variations in the recorded bit length. The recording correcting system may be controlled not only while the apparatus is put to work, but also during unoccupied times when the recording, reproducing, and erasing operations are not required from a higher level apparatus. Also, the controlling operation may be performed so that the value of the record correction may be renewed at proper time intervals. The repetition of the correction trial at the proper interval allows a time lapse after the apparatus power-supply is put to work to occur with no undesirable effects and the characteristic variation between respective discs during the disc exchange can be coped with.

Abstract: An audio visual system includes an audio cassette tape player, a central processor unit, a TV screen for displaying a desired pattern in accordance with a data derived from the audio cassette tape player, and a speaker system for providing audio announcement in accordance with information derived from the audio cassette tape player. The audio visual system displays a problem and five typical answers thereto. The student introduces his answer through a keyboard unit. When, for example, an answer key 3 is actuated, the audio visual system drives the audio cassette tape player to locate a commentary suited for response to the actuation of the answer key 3 whereby the commentary associated with answer key 3 is displayed and announced.

Abstract: An audio visual system comprising a reproduction system for reproducing audio sound information and picture data information recorded on a recording medium, a speaker system for audio sound output purposes, and a color TV screen for providing a visual display in accordance with the picture data information. The picture data information comprises a pattern data and instruction commands for selecting a desired display section on the color TV screen and a desired operation mode to be conducted by the audio visual system. The operation mode can be selected from the entire screen unicolor selection mode, background color change mode, pattern color change mode, display shift mode, small letter display mode, and capital letter display mode.