The Cathode Ray Tube site, Cathode Ray Tubes. (original) (raw)

Karl Ferdinand Braun
1850-1918

The Cathode Ray Tube site

electronic glassware
History and Physics Instruments

The Braun tube, this small early 1900 tube is in fact a cold Cathode Crookes tube with an internal mica screen covered with phosphorescent paint. The neck contains a glass diaphragm with a small 2mm hole to let only a tiny electron beam go through (focus) which can be deflected by an (electro) magnet to produce a spot on the screen. Click here to see the family of educational CRT's sold by Max Kohl early 1900 and here by Müller-Uri.

Thomson's experimental tube
Click on the picture to see the original tube in The Cavendish Lab at the University of Cambridge.

The beginning of the CRT Century which would last more than 100 Years!

In Europe there were several companies active with the early CRT techniques like,
Leybold & Von Ardenne, Emil Gundelach, Philips, Lorenz AG, Telefunken AG, Otto Pressler,
Gladitz GmbH, Fernseh AG, Radio AG, D.S.Loewe, Baird Television, Marconi-EMI and Cossor.
Some of them were closely connected to RCA or the Farnsworth company. Most of these firms
had also long reputations in early science vacuum tube technology.

In the US General Electric, The Bell laboratories, National Union, Westinghouse, RCA Victor,
Farnsworth Television, and Dumont developed their pre-War CRT's.
The first used CRT's were the low pressure argon filled tubes. In these low vacuum tubes the
focus of the beam was regulated by controlling the heater current like the Western 224.
The first US commercial available high vacuum CRT developed by Zworykin, at that time working
for Westinghouse (part of RCA) was the high vacuum RCA 906.

Vladimir Kosma Zworykin demonstrated this tube in the first RCA TV receiver in 1929 and named
the CRT [Kinescope](tv crt.html), it was used with 60 lines at 12 frames per second. Zworykin played an
important role in the electronic TV development, he eventual became director of RCA, in those
days the leading CRT producing company in the US. RCA made large progress in developing
different and better tubes for TV, radar and oscilloscopes.

Farnsworth television also produced for a short period low vacuum tubes for his television
receivers, this CRT's were called Oscillite which never became successful like the RCA tubes.
Another important player on the US CRT market was Allen B Dumont who developed his
own CRT's and started CRT production in 1931 in his garage mainly for oscilloscopes,
later also for Television. There were tubes produced by DuMont with only one deflection plate,
this could be done by placing the gun under an angle pointing towards the side of the tube.
For TV use, magnetically deflecting won over statically deflection due to the high tensions needed
in the deflection amplifier circuits for tubes with large screen sizes.

In Japan Kenjiro Takayanagi at the Hamamatsu Higher Technical Institute worked on CRT
television since 1924. He started the production of high vacuum CRT's in 1930 built by
Dr. Asao at the research Institute of Tokyo Shibura Electric Company. The early CRT displays
were used with 40 lines flyingspot scan techniques, the camera tubes were not yet developed.
In 1936 he presented a 30 Hz 245 lines interlaced all electronic television system. Going further
in 1937 to 441 lines competing with the rest of the world, in 1939 Nippon Electric Company
produced the first domestic TV sets for the Japanese market.

With the increasing TV market, mass production of CRT's was the result.
These pictures above are from the Philips tube factory about 1947.

Philips TV projection tube [1]
This tube with a hollow face to prevented picture distortion on a 40 x50 cm screen.

Philips DW31-2 CRT [6]
This is a 31cm TV tube from 1937.
DW means double electrostatic deflection.
MW means magnetic deflection.
SW means only one pair of electrostatic deflection plates, this can be used
together with magnetic deflection.
The W stands for white phosphor.

Philips TV projection CRT 1949 [1]
Due to distortion problems with bigger tubes Philips developed small projection CRT's.

Early Ediswan CRT [1]
This is one of the first known Ediswan
CRT's with screw connections on the base.
Type AH and BH were sold in 1934 used in the first 30 lines TV receiver.

No, it's not me ! [6]
It's actually a 50cm Telefunken CRT from 1938 with a total length of 85 cm, these were used in mirror TV's.

Joseph John Thomson (1856-1940)
Professor of Physics at the Cambridge University, proved in
1897 that Cathode rays were streams of particles
(corpuscles) that carried a negative charge and were 2000
times lighter than the hydrogen atom and called electrons.

He used his new developed CRT to measure the mass to
charge m/e ratio.
You can find a detailed description here at the University of
Canberra. Thomson's work has been a great contribution to
science and the development of Cathode Ray tubes.
A complete description of Thomson can be found at the
American Institute of Physics including audio recordings of
him about his discovery, definitely a must see web site for
anyone interested.

JJ Thomson developed his tube just slightly earlier than
Braun's tube and has two internal electrostatic deflection
plates instead of the magnetic deflection Braun used in his
early experiments. Although Thomson's type of deflection is
used in many CRT designs, the common name in most
European country's is still Braun tube.

J.J. Thomson in the Cavendish Lab

Cathode Ray Tubes
From the beginning to the end....

Annalen der Physik und Chemie
F. Braun 1897
See [here](Annalen der Physik.html) the translation of the
original German publication.

THE EARLY DAYS OF THE CRT

Allen Balcom DuMont
1901 - 1965

Manfred von Ardenne
1907 - 1997 [1]

Collection of Radio-AG D.S Loewe CRT's 1937.
These are high vacuum tubes. [6]

Two Lorenz CRT's 1937. [6]
Electrostatic deflection for projection use.

Vladimir Kosma Zworykin
1889-1982

Click on the pictures for the original German documentation from Gundelach and information about the Fernseh AG Company.
From this fine web site.
Foundation for German communication and related technologies.

Early RCA TV advertisement

Karl Ferdinand Braun (1850-1918)
A German physicist working at the Physics Institute of the Strasbourg University (from 1895-1918) developed the first cold Cathode Ray tube with magnetically beam deflection.He used a diaphragm and a mica screen covered with phosphor to produce a visible spot. The principle was based on the Crookes deflection tube.
This tube, build for him by Franz Müller, successor of Geissler was called after its inventor, the Braun tube.

Braun used this tube as an indicator tube to visualize alternating currents and described this in 1897, it was in fact the first oscilloscope.

Harris J Ryan introduced a similar tube in 1903 in the USA as an alternating current wave indicator, known as the Braun-Ryan tube.

The first ideas of using Cathode rays (Braun's tube) for Television came from the Englishman Campbell Swinton in 1908. The Frenchman Rignoux and the Russian Rosing experimented also with the Braun's tube for the same reason, just like Belin and Holweck who used Cathode rays for their TV receiver and demonstrated it in Malmaison in 1928.
At that time, mechanical TV was the only way to transmit moving images.

A biography of Braun can be found here.

Television before and during WWII

From the 1930's on, electronic TV developments started in Europe and the US, many companies produced series of electronic TV sets more than 25.000 sets were produced in the US when the War stopped the production. From 1935 the developments in Germany were under strict orders from the Nazi regime, in march of that same year the Fernsehgruppe Paul-Nipkow started their first TV Broadcasting with the Von Ardenne mechanical camera system using film, and later also with Iconoscope cameras at the Olympic Games in 1936, using techniques with permission from RCA and Farnsworth Television.

Companies like Loewe AG and Lorenz AG were held under rigorous military control and Von Ardenne joined like many other German scientists the Nazi regime. From 1939 the TV manufacturing in Germany stopped completely due to the beginning of the War. German Nazi Television, only limited to Berlin for fifty high placed persons and a few public TV places called Fernsehstubes for the propaganda TV. In 1943 after the bombings on Berlin the surviving TV equipment went to occupied France where the Germans built a new TV studio in Paris at 180 Rue de l'Université with the name "Magic City". It was completely built by Telefunken A.E.G and Fernseh AG, and was used until August 16 1943 when they took all equipment back to Germany. Look here for an interesting Dutch television documentary about recently found (1999) original Nazi film-for-TV footage.

In Britain the first public TV BBC Broadcasting started in London 1933 in the Crystal Palace facility, Europe's largest TV studios, home of the Baird television company using mechanical cameras. Although the Baird company had connections with Farnsworth, their Dissector pickup tube was not used due to its poor light sensitivity.
The Crystal Palace burned to the ground in 1936 but Baird's CRT production plant housed in the same building was spared.
After the fire the BBC banned Baird's mechanical camera system and was replaced by the Marconi-EMI all electronic system. (EMI had license cross-connections with RCA) During WWII, the TV production in the US and UK stopped almost completely, development of radar and oscilloscope techniques for the War industry had now more priority. You can find more info about early British television on these fine web sites Baird's Independent Television and Baird Television.
See also the Camera tubes page.