DE2816490C2 - cathode ray tube - Google Patents

Description

3. Cathode ray tube according to claim 1, characterized in that the figure shows a schematic plan view of a characterized in that the binder is a mixed poly color picture television tube 1 with an implosion protection arm is 30 mation 2 and a neck part 8. The conical part of the

4. Cathode ray tube according to claim 1, characterized in that the tube is covered with low-resistance coatings 5 with 3 characterized in that the binder is an acrylic acid - the high-voltage supply is designated by ester is. surround a free area 4, which has a sufficient

Isolation from the coverings applied on the outside

35 guaranteed. This area 4 is preferably still with

covered with a waterproofing varnish
To avoid crackling phenomena are now

The present invention relates to a cathode with the free areas of the conical part of the tube

Radiation tube with a glass cone part, the outer one of which is covered by a high-resistance coating 7, which is shown in the figure

re surface is partially shown with an electrically conductive, 40 hatched and the neck side about

low-resistance coating is provided, which together with up to the limit 6 extends. This high-resistance coating is

an electrically conductive connected to high voltage preferably has a transverse resistance that is approximately

Coating on the inner surface of the cone has a capacitor bil- lOOO times to 10 million times larger than the transverse resistance

det, and its not with the low-resistance coating consisted of the electrically conductive coating 5. The elec-

Covered outer surfaces with a high-resistance, electrically conductive coating 5 expediently consists of one

was made of a mixture of an organic binding, so-called Aquadag covering.

medium and a carbon modification are covered, The high-resistance coating 7 consists of a mixture

The one with the low-resistance coating in an electrical combination of organic binding agent and finely divided soot.

bond and has a transverse resistance, which is the particle size of the organic binder

at least 100 times, in particular at least 100 times, 50 at least 10 times larger than the particle size of the

is greater than that of the low-resistance coating. ßes. A so-called conductive carbon black is preferred as the carbon black

A large number of resistor coverings have already been used. The mean particle size of such a carbon

known from picture tubes that are made from a mixture of bin- ßes, for example, is around 23 nm.

consist of medium and conductive materials. As a conductive material, the organic binder has a particle

Hige materials are especially graphite or egg size from a few tenths to a few hundredths μπι.

senoxide known (DE-PS 9 27 280, US-PS 37 46 904, Polyvinylaceta-

DE-AS 22 57 497, DE-OS 15 14 828 and DE-OS te, copolymers and / or acrylic acid esters in loading

22 40 264). It is also known to add soot to organic pollutants. An aqueous one is used to produce the coverings

Binder for the production of high-resistance layer dispersion applied to the cone,

to use (DE-AS 18 09 363). 60

As far as these wilcrsiaiiuSbclägc üicdcröiiniig are 1 blue drawings

and are located on the outer surface of the picture tube,

are these surfaces mainly due to the chassis potential,
so that changes in resistance such as those caused by atmospheric conditions, 65
do not appear disruptive.

However, if known high-resistance coatings are used on the outer surface of picture tubes, such as

Claims (2)

1 2 it is the case with the generic document DE-PS patent claims: 9 27 280 so it is found that by different temperatures as well as by changing 1. Cathode ray tube with a glass co- humidity, the resistance value is very strong nut part, the outer surface of which can sometimes vary by an amount. Such fluctuations in the negative Electrically conductive, low-resistance coating stand values are, however, for coatings such as those at the beginning marked together with a to high voltage is unsuitable The object of the present invention is to provide The inner surface of the cone forms a capacitor and provides the basis for a cathode ray tube of the initially its not covered with the low-resistance coating 10 named type of specifying a resistance material that outer surfaces with a high-resistance coating its properties even with very different at- from a mixture of an organic binding- atmospheric conditions changes only so little that medium and a finely divided carbon fmodifika- no disturbances occur. tion are covered, with this external high-resistance This task is carried out according to the characteristic of the characteristic Covering with the low-resistance covering in electrical 15 characters of claim 1 solved Connection is and a transverse resistance is due to the application of such a high-resistance if the at least 100 times, preferably the covering, annoying audible crackling 10000 times, is greater than that of the low-resistance side, which is reduced when changes are made to the ges, characterized in that the fine picture tube applied high voltage ergebea distributed carbon modification soot is that the 20 It has been shown that the high-ohmic organic binder particles have their resistance layers in terms of their electrical resistance Surface is covered with the soot and that the parti behavior shows a very high degree of constancy, in particular The particle size of the soot is at least 10 times smaller, especially over a service life of several years is preferably 100 times smaller than that of the binder. Tube. 2. Cathode ray tube according to claim 1, characterized 25 on the basis of the embodiment shown in the figure that the binder is a polyvinyl acetate example, the invention will be explained in more detail below is tert