Process and apparatus for coating display crt tube for electronic device

Abstract

A process for coating a front surface of a cathode ray, the process being characterized by using a ultraviolet ray setting plastic material as a coating material. According to the process, a preformed cathode ray tube bulb having a front surface is maintained with the front surface directed upwards and a transparent, fluidized or molten plastic material of ultraviolet setting property is discharged to the front surface of the bulb through a plurality of thin nozzles arranged in at least one row or one or more nozzles each having an elongated nozzle opening. In this instance, it is preferable that the molten plastic material discharged from the nozzles is received by a film forming surface which is arranged adjacent to the nozzles to form a thin plastic film before it reaches the front surface of the bulb. Preferably, the film forming surface is provided by a sheet of a material, such as a silicon rubber, which is not wettable to the plastic material. The plastic material received by the film forming surface is permitted to flow downwards forming a thin substantially uniform film. The cathode ray tube bulb is moved beneath the film forming surface with the front surface directed upwards. Thus, the front surface of the bulb is coated with a thin film of the plastic material. During the process of forming the coating layer or immediately after the process, ultraviolet ray is applied to the coating layer to set or solidify the plastic material in the layer.