DE1241868B - Electron beam tubes for reproducing color images - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4WMWS PATENT OFFICE Int. CL:

H 04 η

EDITORIAL

HOIj
German class: 21 al - 32/54

Number: 1 241 868

File number: N 26040 VIII a / 21al

Filing date: January 7, 1965

Open date: June 8, 1967

The invention relates to a cathode ray tube with a fluorescent screen for displaying color images, in particular of color television pictures.

A fluorescent screen is often used for the reproduction of color images by means of a cathode ray tube with three phosphors used, which emit blue, green or red light when excited by electrons emit. In order to obtain a bright image, it is necessary that the phosphors have a high efficiency to have. For the blue and green components of the screen, one can choose from a large number of Choose fabrics that meet this requirement. For the red component, the choice is special limited. One of the most widely used substances is zinc cadmium sulfide activated with silver; Another substance that is also often used is zinc orthophosphate activated with manganese.

Internationally, the agreement was made that the color point of the red component of the wavelength 611 must correspond to ηΐμ. Although the red fluorescent substances mentioned above are at this wavelength emitting a sufficient amount of light, they have the disadvantage that they have an emission spectrum with a broad red band and thus have a considerable amount of excitation radiation convert into radiation with wavelengths of 611 ηΐμ. The lumen equivalent is therefore low.

Another particularly important point for phosphors for color display tubes is the so-called "weight of a lumen", which is proportional to 1 / y, where y represents the ordinate of the color point in the internationally established ΧΓΖ color diagram. This "weight" is unfavorable for the well-known red phosphors because of the high v-value.

A cathode ray tube according to the invention for the reproduction of color images has the characteristic on that the luminescent screen contains gadolinium oxide activated with europium as a red component.

Gadolinium oxide activated with europium is already known per se. About using this However, nothing is known of the substance in cathode ray tubes for the reproduction of color images. That with Europium activated gadolinium oxide is particularly suitable for this purpose, as it is when excited with electrons an emission spectrum with very narrow bands in the red part of the spectrum and has particularly strong lines at 612 and 614 ΐημ, i.e. very close to the normalized ones mentioned above Wavelength of 611 πΐμ for the red component.

The lumen equivalent of gadolinium oxide activated with europium is particularly high, namely

Cathode ray tube for displaying
Color images

Applicant:

N. V. Philips' Gloeilampenfabrieken,

Eindhoven (Netherlands)

Representative:

Dr.-Ing. H. D. Zeller, patent attorney,

Hamburg 1, Mönckebergstr. 7th

Named as inventor:

Alfred Bril,

Willem Lambertus Wanmaker,

Christianus Daniel Johannus Cornells de Laat,

Emmansingel, Eindhoven (Netherlands)

Claimed priority:

Netherlands of January 10, 1964 (6 400 107) - -

300 lumens per watt; the well-known silver-activated zinc-cadmium sulfide has a lumen equivalent of only 75 lumens per watt and the zinc phosphate activated with manganese 140 lumens per watt. the The luminous efficacy is between that of the two last-mentioned known phosphors.

The europium content is preferably chosen between 0.5 and 3 mol percent.

Apart from the favorable properties mentioned above, the europium activated gadolinium oxide also a particularly good temperature dependency, d. that is, even at high temperatures a high percentage of the radiation emitted at room temperature is still emitted. Through this it is possible to raise the fluorescent screens in a cathode ray tube according to the invention burden as it z. B. is the case when used to project color television images.

Claims (2)

Patent claims: 1. Cathode ray tube for reproducing color images, characterized in that that the luminescent screen contains gadolinium oxide activated with europium as a red component. 2. Cathode ray tube according to claim 1, characterized in that the amount of europium 0.5 to 3 mole percent of the amount of gadolinium oxide.