Improvements relating to the manufacture of cathode ray tubes

• Main Authors: SEATS PETER, BAYFORD LESLIE JOHN CHARLES, ZOUCH LESLIE ERIC
• Format: Patent
• Language: English
• Published: 15.07.1953
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS; ELECTRICITY

694,232. Luminescent screens for cathode-ray tubes. ELECTRIC & MUSICAL INDUSTRIES Ltd. Dec. 16, 1949 [Dec. 16, 1948], No. 32538/48. Class 39(i) In the manufacture of cathode-ray tubes wherein a liquid film-forming substance is applied to a liquid-covered fluorescent screen of the tube, the film-forming liquid is applied from a dispenser which is supported by a carriage mounted for vertical movement in a guide, the carriage being lowered until the end of the dispenser is in proximity to the liquid-covered screen, whereupon the film-forming liquid is released and the carriage raised until the dispenser is out of the tube, the carriage and guide being so constructed that no vibration occurs to impair the formation of the film during the lowering and raising movement. As shown, the cathode-ray tube envelopes 9, Fig. 1, are held to trolleys 7 by inflatable holders 8, which may be of the type described in Specification 694,233, the trolleys being coupled to an endless belt 6. Along the upper run of the belt the envelopes are charged with phosphor suspension from device 10 and subsequently, the phosphor particles having settled on the base of the envelope, a solution of a film-forming substance is applied from a dispenser mounted on a carrier 11. As each trolley reaches a predetermined position along the upper run of the belt a lever 45, Fig. 3, on the carrier is manually depressed to cause a roller 43 to engage a recess in the trolley and thus couple the trolley to the carrier which is mounted on rails for movement therewith. During movement of the carrier 11, the carriage 23 is automatically lowered whereby dispenser tube 35 is introduced into the envelope. The lower end of tube 35 is provided with a wire 40 (as described in Specification 675,853) which serves to prevent ripples as the solution is delivered on to the liquid surface on the end of the screen, contact of the wire with the liquid automatically actuating a valve (not shown) whereby solution is delivered from reservoir 36 down tube 35. After a predetermined time, the valve is automatically closed, the carriage is raised and the carrier is disengaged from the trolley and moved backwards for coupling to the next trolley in the series. The operations are electrically controlled. During further travel of the envelope the solvent evaporates to leave a film of the organic substance, the liquid beneath the film being discharged down a shoot 55 as the belt passes over pulley 1. In their inverted position along the lower rim of the belt, the envelopes are dried by hot air, the holders 8 being finally deflated and the envelopes removed. Specification 694,286 also is referred to.