DE1614217B2 - Process for the recovery of an excess of phosphor - Google Patents

Description

The invention relates to a method for recovering an excess of phosphor during application a luminescent screen on the inside of a bowl-shaped, essentially rectangular front glass for a cathode ray tube in which a suspension of a phosphor after being introduced into the bowl-shaped front glass by rotating the front glass in an inclined with respect to the horizontal plane Layer is piled evenly over the image area to be coated, after which the speed of rotation is increased in order to achieve an even drying of the layer. Procedure this Art are used in particular in the manufacture of color picture tubes.

A phosphor layer is generally applied to the inside of a bowl-shaped front glass applied to a picture tube by placing a phosphor suspension on approximately the center of the inner surface of an in Rotation offset front glass is poured. The suspension then gradually flows to the edge of the picture surface, and the excess piles up on the edge.

If the plane of rotation of the front glass is inclined, the excess flows to one side and then flows along the edge of the picture surface and along the raised edge of the front glass. Finally will the speed of rotation increased in order to achieve an even drying of the screen.

In the case of round front glasses, this excess can be easily mixed with one near the inner wall the stationary suction device attached to the front glass can be removed and recovered.

In the case of essentially rectangular front glasses, however, the suction device must be at the edge of the image area follow, requiring an intricate design.

The application is based on the task, in the case of the method mentioned at the beginning, on the edge of the picture subject to remove and recover any accumulated excess suspension.

This is achieved in that according to the invention before turning the front glass collecting container for Catch the excess fluorescent suspension from the outside against the corners of the front glass and held pressed against the corners, the collecting containers can be made of a flexible material be made.

depending on the excess amount of the suspension If necessary, the collection containers can be used several times before the collection Suspension must be removed.

The invention is explained in more detail below for an exemplary embodiment with reference to the drawing.

It shows

F i g. 1 is a plan view of a front glass rotating in an inclined plane,

F i g. 2 shows a section through a corner of the front glass according to FIG. 1,

F i g. 3 is a perspective view of a collecting container according to the invention.

In the drawing, 1 denotes the image area of a bowl-shaped front glass with a raised one Edge 2. The front glass is not yet connected to the cone of the color picture tube.

The front glass is attached to a receiving device 3, which can be set in rotation. Before that, however, collecting containers made of pliable and preferably plastic material are made 4 set against the edges 2 at the corners of the front glass. Springs 5 press the collecting container 4 firmly on. Then a phosphor suspension 7 is applied approximately to the center of the inner surface of the rotating front glass 1 poured, flows to the edges and forms a uniform luminous layer on the picture surface. the The plane in which the front glass rotates is arranged at an angle, so that the excess of phosphor suspension is 7 accumulates at the edge and flows along the edge of the screen surface. Then the speed of rotation of the front glass 1 enlarged to dry the screen. This will make the excess of phosphor suspension 7 due to the centrifugal force at the corners of the front glass 1 in the collecting container 4 hurled, as in F i g. 2 is shown.

The collecting containers 4 have a device shown in FIG. 3 shown suitable shape in such a way that the excess of phosphor suspension 7 can be completely collected therein.

The collecting containers 4 can optionally be used to collect the excess of phosphor suspension 7 several front glasses 1 are used before the amount of phosphor suspension 7 collected therein must be removed, which is then subsequently fed to the recovery. This recovery is necessary because the fluorescent suspension 7 for the production of screens for the color picture tubes very much is expensive. In addition, by the method according to the invention, splashing around of the excess occurs Phosphor suspension 7 prevented.

The collecting container 4 can also be designed differently.

1 sheet of drawings

Claims (2)

Patent claims: 1. Process for the recovery of an excess of phosphor when applying a Luminous screen on the inside of a bowl-shaped, essentially rectangular front glass for a cathode ray tube in which a suspension of a phosphor after being introduced into the bowl-shaped front glass by rotating the front glass in a relative to the horizontal Flat inclined position evenly distributed over the picture surface to be covered and the excess the suspension is accumulated at the edge of the picture surface, after which the speed of rotation increases is, in order to achieve an even drying of the layer, characterized in, that before turning the front glass (1) collecting container (4) to collect the excess placed on fluorescent suspension (7) from the outside against the corners of the front glass (1) and on the corners be held down. 2. Apparatus for performing the method according to claim 1, characterized in that the Collecting container (4) consist of a flexible material.