Verfahren und Einrichtung zur Unterdrückung des Flimmerns bei der Wiedergabe eines Fernsehbildes.

摘要

584,916. Television. GES. ZUR FORDERUNG DER FORSCHUNG AUF DEM GEBIETE DER TECHNISCHEN PHYSIK AN DER EIDGENOSSISCHEN TECHNISCHEN HOCHSCHULE. Oct. 22, 1943, No. 17454. Convention date, Jan. 25. [Class 40 (iii)] Flicker is eliminated or reduced in a television receiver in which the image is produced by modifying the optical characteristics of elements in a continuously illuminated raster by means of a flicker wheel or like which causes periodic reduction of the illumination of the image additional to that produced by the waxing and waning of the modulation due to scanning. The receiver is similar to that described in Specification 543,485. Light from a source 11 is directed through a grille 15 and lens 16 and through the transparent disc 2 included within the receiving tube and carrying a transparent fluid film 1 which is deformed in accordance with charges induced by a scanning cathode-ray beam 9. The grille 15 is imaged by lens 16 on the elements of another grille 17 so that light only reaches screen 25 when and where film 1 is deformed, thus producing the received image on screen 25. The flicker wheel 28 is introduced just in front of the disc 2. The wheel is formed with sectors of varying opacity and is rotated in synchronism with the scanning. In one form the flicker wheel is formed with sectors comprising a number of radially-extending opaque fillets of varying width. In another form, the disc includes transparent sectors separated by opaque bars for producing the required interruption and in a variation of this form two similar discs are employed which may be separately rotated in synchronism either by the same or different motors, but with adjustable phase displacement to afford a controlled light interruption. The flicker wheel may be included in the cathoderay tube and may serve as a grid for collecting secondary electrons emitted from the film 1. The opacity of the flicker wheel may be adjusted to correct for variation in the illumination of the raster ; also the wheel may be inserted immediately in front of the viewing screen 25. The film 1 is slightly electrically conducting and is discharged and smoothed by a scraper 3 after being cooled by fluid circulating in cooler 4.