Patent GB-1251981-A (GB)
IPC: C03C17/00
Filed: 1968-08-16
Abstract: 1,251,981. Automatic continuous vacuum deposition apparatus. LIBBY & OWENS-FORD CO. Aug. 16,1968 [Aug.30, 1967], No.39192/68. Heading C7F. Automatically controlled apparatus for continuously vacuum coating glass or plastics sheets comprises a series of vacuum chambers interconnected end to end, a conveyor for passing the sheets through and discharging them from the chambers, carriers for vertically supporting the sheets on the conveyor and valves situated at the inlet and outlet of the series and between each chamber which are sequentially opened and closed according to the carrier's position in the chambers. The sequential and automatic opening or closing of the valves is effected through a circuit activated by limit switches contacted by the carriers when in the required position in the chambers. The circuit includes pressure switches pre-set to opwrate hydraulic pistons attached to the valves when the required chamber pressure is attained. The sequence of operations which is automatically controlled by limit switches, relays, timing devices, cams solenoids, hydraulic pistons, motor drives and chain belts all inter-connected in various circuits is shown generally in Figs. 1-3 (not shown). The glass sheets suspended at 7 degrees to vertical are washed at 22, rinsed and dried at 23 with air blast ionized in A.C. corona discharge, transferred to inspection station 24 and then via turntable 27 sheets are loaded in pairs and positioned vertically on loader 28. Sheets are automatically transferred via conveyor 150 to a bridging carrier 135 at station 10 and advanced through side 11 of transfer area 12 to entry 13 by conveyor unit 145 of vacuum chambers. Carriers are then transported in direction E through the vacuum chambers by conveyor with individual drives for eachconveyor section in each vacuum chamber. The conveyor comprises a pair of parallel monorails in each chamber and an endless chain belt. The carriers are supported by and move along the monorails and carry magnetized members for engaging the chain belt. The magnetized members are arranged so that the spacing allows continuous movement of the carriers through the chambers. The apparatus includes the following vacuum chambers in series, through which the sheets are sequentially passed:- 350 - De dusting chamber. Sheets subjected to jet of partially ironized air. 360 - Inlet valve. 370 - Entry chamber evacuated to 2 x 10<SP>-1</SP> to 5 x 10<SP>-3</SP> torr during travel of sheets. 361 - Second valve. 390 - Glow discharge cleaning chamber. 0 2  introduced to maintain 1 x 10<SP>-2</SP> to 1 x 10<SP>-3</SP> torr. 362 - Third valve. 420 - Pre-heating chamber, 1 x 10<SP>-4</SP> to 1 x 10<SP>-6</SP> torr, 200-700‹F. 363 - Fourth valve. 440 - Vacuum coating chamber, 1 x 10<SP>-4</SP> to 1 x 10<SP>-7</SP> torr. Electron beam evaporation sources arranged in vertical and horizontal rows in walls. Sources same or different, introduced through electron gun as powder or wire. First layer of C+ deposited and second layer of SiO 2 . Al coating deposited on unheated surface. Metal oxides or metal halides may be deposited. 364 - Fifth valve. 470 - Cooling chamber. Pressure raised from 1 x 10<SP>-4</SP> to 1 x 10<SP>-7</SP> to 2 x 10<SP>-1</SP> to 5 x 10<SP>-3</SP> torr. 365 - Sixth valve. 490 - Up to air chamber. Pressure increased to atmospheric during travel of sheets through chamber. 366 - Exit valve. The carriers with the coated sheets are transferred from exit 15 across transfer area 16 by shuttle transfer carrier 510 on to return monorail conveyor system 18. Conveyor drive units 550, 551, 552, 553 transport loaded carriers via conveyor drive 152, bridging carrier 136 and unloading conveyor drive 151 to discharge sheets at unloader 29. Empty carriers are then transferred to shuttle carriage 120 which carries them to loading station 10 via bridging carrier 135. Cycle is then repeated. The conveyor in the coating chamber 440 is divided into three sections driven at different speeds. The entry section travels e.g. at 80 f.p.m., the centre at 2-8 f.p.m. and the exit section at 80 f.p.m. The speed change is automatically effected via electromagnetic clutches and sprocket wheels. Up to 3 pairs of sheets in three carriers may be located in coating chambers 440 at one time and an integrating pulsing device operated by the pulses generated from the drives of the three sections monitors the distance between the carriers in the chamber.