THE RADIOVISION CHRONICLE
By Roger DUPOUY
1931 to 1935 : Moving from 30 lines to 180 lines.
14th of April 1931: First Public Television Demonstration.
This demonstration was done in 30 lignes of definition. Its used the equipments, machines and devices of the Montrouge's C.D.C television laboratory, managed by René BARTHELEMY.
The demo took place at the Electricity High School located in the city of Malakoff near Paris. At that time, the TV transmitter was in C.D.C. Montrouge, using a 30 mirrors drum camera for flying spot analysis. On the other side, in Malakoff, a the receiver with a scanning disc reproced the image. It was a Brillouin-type disc equiped with lens in place of holes to give more light. The image was spread on a square grounded glass of abour 40 centimeters in size. In order to have the large audience to see the images, three mirrors reflected the image in front of the public (see photos). By then, BARTHELEMY's work on the 60 lines definition is going on, but no formal demo are possible yet.
25th. of April 1935.
Celebrating the First 60 lines Television Broadcasting.
On the photo below, in front of the camera, Miss Beatrice BRETTY, a famous actriz of the Comédie Française, tell the audience about her trip in Italy with the actors.
In front of Her, behind the glass put in place to isolated from the motor's noise, one can see the 60 lines mechanical camera.
This demonstration took place at the PTT studio, 103, rue de Grenelle - Paris. Most of the TV receivers used by then to watch the transmission were cathodic.
At that time, BARTHRELEMY, pressed by the PTT Minister , George MANDEL, hardly worked on the 180 lines defintion, to compete with the German. This task found its achievement by end 1935!
This took place at the same location as for the previous 60 lines at the PTT studio. The 180 lines mechanical camera has a two spirals special scanning disc, which speed is 3000 rpm. It has very tiny hole and the loss of light through them is considerable.
Consequently, the studio need as much as
50.000 lux, of light to satisfy the camera.
A special cooling system has to be put in place to lower the temperature from around 55 degrees to around 24 degrees. By that time, the 180 lines receivers were fully cathodic.
End 1936, mark in France the end of the 60 lines programs and consiquently, the end of mechanical television.
See article by Paul BERCHE: 1st official television demonstration