GB869397A - Method and apparatus for filming articles by vacuum deposition - Google Patents

Abstract

869,397. Coating by vapour deposition. LIBBEY-OWENS-FORD GLASS CO. June 29, 1959 [July 2, 1958], No. 22167/59. Class 82(2) Sheets are coated by vapour deposition in an evacuated chamber by sealing a sheet in an intake chamber, simultaneously evacuating said intake chamber and cleaning a side of the sheet to be coated transferring the sheet through an opened communication to the coating chamber, closing the communication, coating the sheet while evacuating a discharge chamber, transferring the coated sheet through an opened communication to the evacuated discharge chamber, closing the communication, bringing the discharge chamber up to atmospheric pressure, and removing the coated sheet therefrom. The sheets may be glass, metal, or plastic. As shown, sheets 48 of glass in carriers 49 move successively into positions F, E, D, C, B, and A in intake chamber 21, cleaning chamber 22, coating chamber 23, and discharge chamber 24. When intake chamber 21 is empty, valve 26 is opened to the atmosphere, and the chamber supplied with dry air from dryer 25 to prevent the ingress of moisture. Fresh sheets 48 are charged, valve 26 closed, and vacuum pump 28 begins to reduce the pressure in the chamber. During the first portion of the evacuation dust free air is directed from guns 29 on the surface of the glass and dust collected at 30. Plutonium probes 31 prevent the formation of a static charge on the glass which may be heated meanwhile by heaters 32. When chamber 21 reaches a pressure of 10<SP>-3</SP> mm. Hg, valve 27 is opened and the sheets are advanced to position E in cleaning chamber 22 where they are further heated by heaters 33. At position D the sheets are glow discharge cleaned in a confined inner chamber 34 by a glow plate 35, the vacuum in the chamber being reduced while cleaning from 10<SP>-4</SP> mm. Hg to 1-10 microns Hg by introducing oxygen through pipe 37. In positions C and B the sheets are moved to at least 40 inches from evaporant sources 39 and 40 which are screened from each other by baffle 41. The vacuum chamber 23 is maintained at 10<SP>-5</SP> mm. Hg by pump 43. The coated sheets pass through valve 45 to discharge chamber 24 from which they can pass via valve 46 and out of the apparatus. A modification discloses the intake, cleaning, and discharge chambers made equal in width to the vacuum chamber (Fig. 7 not shown) so that it is unnecessary to provide equipment for moving the carriers away from and towards the centre line in the vacuum chamber. In another modification (Fig. 8 not shown) parallel pairs of intake, cleaning, and discharge chambers are used to overcome the same problem while, in a further embodiment (Fig. 9 not shown) a modified vacuum chamber is used in which evaporant sources 39 and 40 are adjacent the outer walls of the chamber so that the carriers are able to travel through each chamber without diversion from a straight line path.