Fabrication method for cathode ray tubes uses low-cost siloxane resin formulations. The resins contain sufficient methyl or phenyl groups for solubility in organic solvents. After vaporization and baking, the polymerized material is stable under vacuum and under temperatures required for tube fabrication

Bullinger, H.

Hilborn, E. H.

English

NASA Technical Reports Server

September 1970
	
Brief 70-10454 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Multilayer Screen Gives Cathode Ray Tube High Contrast 
Phosphor
Ultraviolet Transmitting Layer 
Fluorescent Laver_.......ø.} ___	 - ------	
-
*--__ Tube Face 
Long Wave Bandpass Filter
Antireflection Layer 
Fabrication Layers of High Contrast Cathode Ray Tube 
Designers and manufacturers of display instruments 
should know about this novel fabrication method 
for high contrast cathode ray tubes. This technique 
features compatibility with vacuum bakeout pro-
cedures and temperature, conformability to curved 
surfaces, applicability to large areas, use of ordinary 
tooling procedures, and economy of manufacturing 
operations. 
To remove tube size limitations and permit eco-
nomical fabrication, low-cost siloxane resin formula-
tions containing particulate or dissolved materials 
substitute for expensive thin glass filters and fluores-
cent glasses previously, employed. The resins contain 
sufficient methyl or phenyl groups for solubility in 
organic solvents. After vaporizing the solvent, a short 
baking cycle drives off the organic groups, leaving a 
polymerized material stable under vacuum and under 
'the temperatures required for tube fabrication. 
The fabrication method provides for low diffuse 
reflectance of ambient light. Employing nonreciprocal 
filtering overcomes objections to earlier approaches 
or applications involving high ambient illumination 
vels, such as in aircraft cockpits.
The cathode ray tube face consists of a layer of 
ultraviolet emitting phosphor upon which the electron 
beam impinges; a second layer of shortwave bandpass 
filter material to transmit this energy; a third layer of 
fluorescent material that converts the short wave-
length energy into visible energy; and a final layer 
consisting.of a longwave bandpass filter which trans-
mits this visible energy, while simultaneously blocking 
shortwave energy which could stimulate the fluores-
cent layer. Since the two filters have no mutual band-
pass, no ambient energy can reach the phosphor layer 
to be reflected with concomitant reduction in the 
contrast of imagery displayed on the tube face. The 
tube face appears black except where information is 
being presented. 
An embodiment of the invention is shown in the 
drawing. The tube face serves as a substrate upon 
which several layers are deposited. Powdered fluores-
cent glass in a glass resin carrier comprises the fluo-
rescent layer. After applying the formulation and 
drying to obtain a thickness of 3 to 10 mils, baking 
the coating polymerizes the resin. The fluorescent 
glass used must have reasonable conversion efficiency 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19700000438 2020-03-17T00:48:59+00:00Z
and a refractive index matching that of the glass resin. 
The ultraviolet transmitting layer (see drawing) 
must be thin to avoid lateral spreading of energy from 
the phosphor into the fluorescent layer. This require-
ment eliminates the need of matching refractive in-
dices, since the broadening due to refraction in thin 
layers is negligible here. 
A thin film of magnesium fluoride is evaporated 
on the front surface to reduce further the ambient 
illumination.
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: TSP70- 10454 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: E. H. Hilborn and H. Bullinger

Electronics Research Center

(E RC- 10217) 
Brief 70-10454	 Category 01


Multilayer screen gives cathode ray tube high contrast

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