GB1578491A

GB1578491A - Television display tube

Info

Publication number: GB1578491A
Application number: GB1138678A
Authority: GB
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1977-03-25
Filing date: 1978-03-22
Publication date: 1980-11-05
Also published as: FR2385218A1; NL7703233A; DE2810781A1; JPS53118971A

Description

(54) TELEVISION DISPLAY TUBE (71) We, N.V. PHILIPS' GLOEILAM PENFABRIEKEN, a limited liability Com- pany, organised and established under the laws of the Kingdom of the Netherlands, of Emmasingel 29, Eindhoven, the Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: The invention relates to a television display tube comprising means to generate three electron beams, a display screen comprising regions of substances luminescing in three different colours, and a colour selection electrode having apertures for assigning each electron beam to luminescent regions of one colour, said apertures being arranged in substantially vertical rows in such manner that the outer rows follow the slightly curved side edges of the colour selection electrode.

Such a television display tube is disclosed in British Patent Specification 1,442,877.

In such a television display tube the distances between the rows of apertures in the colour selection electrode cannot, of course, have the same value everywhere. It has been found, however, that a so-called varying mask pitch is often annoying to the viewer.

It is the object of the invention to provide a television display tube of the kind mentioned in the preamble in which the mask pitch varies in such manner as to reduce this annoyance.

According to the invention there is provided a television display tube comprising means to generate three electron beams a display screen comprising regions of substances luminescing in three different colours, and a colour selection electrode having apertures for assigning each electron beam to luminescent regions of one colour, said apertures being arranged in substantially vertical rows in such manner that the outer rows follow the slightly curved side edges of the colour selection electrode, characterised in that the distances between the rows along any horizontal line over the surface of the colour selection electrode are equal and the distances between the rows regularly decrease from the horizontal centre line towards the upper and lower edges of the colour selection electrode.

An embodiment of the invention will be described by way of example in greater detail with reference to the accompanying diagrammatic drawing, in which: Figure 1 is a sectional view of a television display tube embodying the invention, and Figure 2 is a front elevation of the colour selection electrode of the tube.

The television display tube shown in Figure 1 comprises in a glass envelope 1: means 2 to generate three electron beams 3 4 and 5, a display screen 6 having phosphor regions luminescing in red, green and blue, and a colour selection electrode 7 (shadow mask) having a large number of apertures 8 for assigning each of the electron beams 3,4 and 5 to phosphor regions of one colour. The tube furthermore comprises a set of deflection coils 9 to deflect the electron beams 3, 4 and 5 over the display screen 6.

Figure 2 is a front elevation of the colour selection electrode 7. The apertures 8 are arranged in vertical rows, four of which are referenced 10, 11, 12 and 13, some other rows being shown only by their centre lines: the actual number of rows is much larger than can be shown and the apertures and their mutual distances are much smaller than can be shown. As shown in Figure 2 the extreme right-hand row 13 follows the right-hand edge 14 of the colour selection electrode 7. The central row 10 is straight.

The curvature of the rows increases gradually towards the left-hand edge 15 and the right-hand edge 14. The distances between the rows along any horizontal line, for example horizontal line 16, are equal. Along a horizontal line through the centre of the colour selection electrode the pitch is, for example, 0.770 mm and towards the upper and lower edges said horizontal pitch gradually decreases to, for example 0.733 mm in a display tube having a screen diagonal of 66 cm and a maximum deflection angle of 110 .

WHAT WE CLAIM IS: 1. A television display tube comprising means to generate three electron beams, a diaplay screen comprising regions of substances luminescing in three different colours, and a colour selection electrode having apertures for assigning each electron beam to luminescent regions of one colour, said aper tures being arranged in substantially vertical rows in such manner that the outer rows follow the slightly curved side edges of the colour selection electrode, characterised in that the distances between the rows along any horizontal line over the surface of the colour selection electrode are equal and the distances between the rows regularly decrease from the horizontal centre line towards the upper and lower edges of the colour selection electrode.

2. A television display tube substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. horizontal line through the centre of the colour selection electrode the pitch is, for example, 0.770 mm and towards the upper and lower edges said horizontal pitch gradually decreases to, for example 0.733 mm in a display tube having a screen diagonal of 66 cm and a maximum deflection angle of 110 . WHAT WE CLAIM IS:

1. A television display tube comprising means to generate three electron beams, a diaplay screen comprising regions of substances luminescing in three different colours, and a colour selection electrode having apertures for assigning each electron beam to luminescent regions of one colour, said aper tures being arranged in substantially vertical rows in such manner that the outer rows follow the slightly curved side edges of the colour selection electrode, characterised in that the distances between the rows along any horizontal line over the surface of the colour selection electrode are equal and the distances between the rows regularly decrease from the horizontal centre line towards the upper and lower edges of the colour selection electrode.