Thomson Consumer Electronics Inc.

Rca Licensing Corporation

Andrew Good

Bruce G Marks

Frank R Ragland, Jr

Richard C Bauder

Thomas D Welles, Jr

A color picture tube has a rectangular shadow mask mounted therein in spaced relation to a viewing screen. A major axis passes through the center of the mask and parallels the long sides thereof and a minor axis passes through the center of the mask and parallels the short sides thereof. The mask has an aperture array that includes slit-shaped apertures aligned in columns that essentially parallel the minor axis and end at a border of the aperture array. Adjacent apertures in each column are separated by tie bars in the mask that are longitudinally offset from column to adjacent column. The spacing from tie bar to tie bar in a column is the tie bar pitch at a location on the mask. A first set of the aperture columns, comprising every other column, has full length ultimate apertures at least at one end thereof, and a second set of the aperture columns, comprising every other column not in the first set, has partial length ultimate apertures at least at one end thereof. The ultimate apertures of all of the aperture columns end on smooth curved border lines. The tie bar pitch of the columns decreases from the center of the mask to the short sides thereof, with the tie bar pitch in the region of the short sides of the mask being optimized to minimize moire at the sides of the screen during tube operation. The tie bar pitch along each column varies also from the center of the mask to the long sides of the mask.

Color picture tube shadow mask having improved mask aperture pattern

The present invention is an improvement in a method of screening a line screen slit mask color picture tube that includes coating a faceplate panel of the tube with a photosensitive material, inserting a slit shadow mask into the panel and exposing the photosensitive material by passing light from a line light source through a misregister correction lens and through the slits of the mask. The improvement comprises positioning a skew correction lens between the line light source and the misregister correction lens during exposure of the photosensitive material. The skew correction lens has a surface with a general overall cylindrical shape with deviations from the cylindrical shape being in the four corners of the skew correction lens.

Method for screening line screen slit mask color picture tubes

An improved color picture tube includes a shadow mask which has a rectangular periphery with two long sides and two short sides. The mask has a major axis, which passes through the center of the mask and parallels the long sides, and a minor axis, which passes through the center of the mask and parallels the short sides. The mask includes slit-shaped apertures aligned in columns that essentially parallel the minor axis. Adjacent apertures in each column are separated by tie bars in the mask. The widths of the tie bars are graded in dimension. The grading is at least partially related to the amount of tie bar stretch occurring in a similar size mask having different tie bar widths.

Color picture tube having shadow mask with improved tie bar grading

An improved method of making a color picture tube shadow mask includes first constructing an apertured flat mask which is formed into a domed contoured mask. The mask has a rectangular periphery with two long sides and two short sides. The mask has a major axis, which passes through the center of the mask and parallels the long sides, and a minor axis, which passes through the center of the mask and parallels said short sides. The mask includes slit-shaped apertures aligned in columns that essentially parallel the minor axis. Adjacent apertures in each column are separated by tie bars in the mask, with the spacing between tie bars in a column being the tie bar pitch at a particular location on the mask. The improvement comprises a first step of calculating the desired tie bar shadow locations at several discrete areas, for a given scan line pitch, as viewed from a distance in front of a viewing screen of a tube. The desired tie bar shadow locations are those locations that will give an optimized compromise for moire at each of the discrete areas. Next, the corresponding tie bar shadow locations on the screen are determined, taking into account the angles of the screen slope at the discrete areas. The corresponding tie bar pitches are then determined on a formed contoured shadow mask, taking into account the mask to screen spacing at each of the discrete areas. Then, the tie bar pitches on the unformed flat mask are calculated, by subtracting the stretch caused by the mask formign step. The stretch is determined by actual measurements of vertical pitch at the discrete areas on the apertured formed mask and by comparing these measurements with measurements made on the flat mask prior to forming. Finally, a least squares fitting is performed on the calculated flat mask tie bar pitches, to obtain the locations of tie bars at all areas on the flat mask.

Growing community of inventors

Reamstown, PA, United States of America

Andrew Good