DK351274

• Main Authors: BOUWHUIS G, BRAAT J J M, JACOBS B A J
• Format: Patent
• Language: English
• Published: 24.02.1975
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

1479294 Optical recording PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 28 June 1974 [2 July 1973] 28824/74 Heading G5R In an optical record and playback arrangement for disc records in which the track width is less than the diameter of the radiation playback spot and in which the average number of recorded areas g per unit length of track varies e.g. as in a video disc with a frame recorded in each turn of the track, the width of the recorded areas is increased in proportion to the increase in said average number. The arrangement is particularly described with reference to a reflecting optical record of the type having areas g which vary in length with the recorded information and which are depressed “ wavelength of the playback radiation so that an antiphase radiation is produced in the playback detector as an area g is scanned in cancelling relationship to that reflected from the land 3 between tracks and the space t between recorded areas. As the length of the recorded areas decreases the average amplitude variation of the detected signal also varies so the width of the areas j is increased to compensate. In addition the non-linearity evidenced by the detector signal dropping to more than half the difference between maximum and minimum before the start of an area reaches the mid point of the playback spot, is compensated by shaping of the leading and trailing ends of the recorded areas. Figs. 9 and 10 (not shown). Recording apparatus for the disc for producing these changes in the shape of the recorded areas is described Fig. 11 (not shown).