Nokia (deutschland) Gmbh

Matsushita Electronics (europe) Gmbh

Nokia Technology Gmbh

Nokia Unterhaltungselektronick Gmbh

Rolf Reidinger

Heinz Beckerle

Rolf Schmidt

Werner Wolfram

Heinz Lagger

Stefan Fischer

Heinz Becker

Heiko Fichtler

Werner Wolffram

The invention refers to a method of manufacturing color CRTs, in which the reject rate is reduced in by increasing the viscosity of the cleaning bath.

Method of manufacturing color CRT's

A color picture tube having a mask-frame combination which consists of a rectangular frame of a first material and of a mask of a second material, wherein the mask is connected to the frame by a plurality of welding spots, and notches and decoupling slots whose dimensions have a specific ratio with one another are provided at both sides of welding spots at the shorter sides.

Color picture tube having a mask of a first material connected to a

According to the prior art, springs (11/18) of a combination mask/frame (10) of picture tubes are joined to the frame by resistance welding. This welding technique is also customary when one of the springs (18) has a centering washer (20) at its free end. When combination mask/frames (10) designed in this manner are snapped repeatedly into and out of the shielding case (15), and when the shielding case (15) is stabilized or fritted to the neck of the picture tube, it can happen that the expansion characteristics of the combination mask/frame (10) are not homogeneous at the fourth spring (18) as compared to the other springs (11) under the picture tube's operating conditions. According to the invention, the centering washer (20) is joined to the spring (18) by laser welding, with laser beams (24) striking the side of the spring (18) facing the frame (10) from the inside (22) of the combination mask/frame (10), and joining the welding grooves (25) arranged in the spring (18) at their edges (26) to the centering washer (20).

Picture tube having centering washer and spring for joining a mask/frame

The following steps are performed in a method of lacquering the luminophore layer of a color picture tube: the luminophore layer is first prewetted, a first aqueous dispersion of a lacquer is applied to the prewetted luminophore layer, this first dispersion is fully dried and heated to above the film formation temperature of the lacquer, thereby producing a first lacquer film, a second aqueous dispersion is applied directly to the first lacquer film, where the said second aqueous dispersion has exactly the same components as the first dispersion and the concentration of the components in the second dispersion corresponds at least to a large extent to the concentration of these components in the first dispersion, and this second dispersion is fully dried and heated to above the film formation temperature of the lacquer, thereby producing a second lacquer film. This two-stage lacquering process makes it possible obtain screen brightnesses that are about 10% greater than can be obtained by means of conventional single-stage lacquering methods.

Method of lacquering the luminophore layer of a color picture tube

A mask-frame combination for a color picture tube includes a metal mask (12) placed over the frame with a skirting that overhangs the frame with an overhang height (H) and that is bent back toward the frame, and includes spot welds (15.1-15.12) located around the mask skirting for attaching the mask to the frame, wherein the mask skirting (13) bears against the outside of the frame (11) for attaching the mask where it is bent back, wherein the spot welds are arranged on each side of the long sides in such a manner that in each long side there is a central spot weld situated close to the mid-point of the long side and an outer spot weld on each side of the central spot weld and separated from the central spot weld by a distance of between D/14 and D/9, where D equals the length of the diagonal of the frame, and wherein the mask skirting is provided on each long side with openings (17) on two sides of each outer spot weld and adjacent thereto.

Mask-frame combination for a color picture tube

The following steps are performed in a method of lacquering the luminophore layer of a colour picture tube:

In a combined mask/frame for a colour picture tube, a mask is attached to a frame by means of spot welds which are positioned at the corners and adjacent to the long center axis and the short center axis. Of central importance is the fact that all spot welds are arranged as double spot welds instead of single spot welds which were usual until now. The single spot welds of each double spot weld are located basically at the same height of the mask skirt but are slightly separated from each other.

Growing community of inventors

Ebersbach, Germany

Rolf Reidinger