Patent GB-1402378-A (GB)
Title: Video information storage and retrieval systems
IPC: G11B27/024
Filed: 1973-07-11
Abstract: 1402378 Video information storage and retrieval VIDEOFAX COMMUNICATIONS CORP 11 July 1973 [17 July 1972] 33112/73 Heading H4F In an arrangement for storing and retrieving documentary information, a T.V. camera, operated at a line scan rate which is a multiple of an established standard and a frame rate which is a corresponding sub-multiple of the standard, scans the document to produce high-definition video signals which are divided into contiguous, equal sections, such sections being temporarily stored on separate continuous tracks (e.g. on a disc or endless loop) and then transferred sequentially from the tracks to a permanent store comprising a recording medium suitable for recording only standard rate signals, e.g. magnetic tape, the retrieval mode then consisting of playing back the signal sections from the latter medium and re-recording them on the separate continuous tracks which are then played back to reconstitute the high definition video signal. With this arrangement the retrieved documents may be displayed with the same high-definition in which they were originally scanned without the need to employ extensive high-definition recording and storage apparatus for the permanent store. Fig. 1, shows the general arrangement in which the T.V. camera 12 operated at 1575 lines and 10 frames, (i.e. the multiple is three and the sub-multiple one-third, of the U.S. standard of 525 lines and 30 frames), scans the document 10 to produce corresponding high-definition video signals which are divided into three equal contiguous sections (each of 525 lines occurring in 1/30 sec.-the standard rate), such sections being temporarily recorded sequentially on individual endless tracks on a conventional magnetic disc storage recorder 14. Such recording may be effected by a set of three heads which, when another group of signal sections corresponding to a different document is to be recorded, may be mechanically indexed to the next set of three tracks or, alternatively, as many, electronically commutated, heads as there are tracks may be employed. In operation a "double-run" is effected, the first recording being viewed on a monitor 17 for test purposes and after erasure of which a second recording run is effected. The signals so recorded are then transferred (and thereby erased from the disc) to a standard magnetic tape recorder 13 on which they recorded, as shown in Fig. 2, in three respective adjacent addressed sections forming the permanent store. When retrieval of a document so stored is required a suitably addressed request causes the information in store 13 to be played-back and recorded on separate tracks on disc recorder 14 which is then played-back to provide the high-definition (1575 lines) for display on tube 16. Since the frame rate of such display is only ten frames per second the phosphor on the screen of tube 16 shows a square-wave decay characteristic and a persistence that suppresses a 10Hz flicker, this being feasible since the scanned document is stationary. Alternatively, a cathodochromic display may be employed or the speed of this disc may be increased by a factor of three. In this latter case, however, mechanical considerations set a limit of about 1200 r.p.m. for recording from the tape and 3600 r.p.m. for display. When the document contains coloured illustrations as well as printed text the latter is stored as described above whilst the former is stored by scanning with a conventional colour T.V. camera and temporarily storing the blue, red and green components on three separate tracks on the disc from which the components are transferred to the same tape on which the printed text is stored. In play-back, i.e. the retrieval, the colour component sections are played-back simultaneously to recreate the colour images whereas the sections containing the text material are played-back sequentially. The general organization of the system in which, employing existing common carrier lines, user stations may call-up display and make hard copies of available documents stored in a permanent store by a filing station is described with reference to Fig. 3 (not shown).