Ok je vais continuer en anglais, parce que mon francais n´est pas le meilleur, si vous permettez..
Here is a timeframe for the logos

The 1st Logo from 1963, when the ZDF started. The creator of that Logo was an Illustrator and Designer named Woldemar G. Hörnig. In fact, before the Programm started on 1st of April 1963, there was a Logo-contest for all german designers. On 16th of January 1963 Hörnig won 1st prize and his Design was used from then on. He also got 6000 Marks for winning the contest. That logo was used in many different variations until 1992. Here are a few of them



The first three here were mostly used in print, the last one replaced the first on-screen design in 1970. It was used on screen till about 1972.
This Variation was only used to announce color-transmissions from the end of the 60s till about 1971. The Cube was animated, it was spinning and changing colors. Germany started in 1967 with color television.

In the seventies about 1973, they started to concentrate more to the three letters ZDF,so the first picture here is an example of that. There were also different variations. The second picture was then mostly used when the ZDF was signing off late at night until 1992.



The early eighties from 1981 on had the slogan "ZDF Ihr Programm-Your Program" This went on a few years, then the slogan was dropped as you can see in the last picture. The first major change came then in 1992:
The old logo with the two interlocked eyes and the two transmission poles was replaced with this design which was used until 2001.
when they changed their whole corporate design. Since the ZDF always was for german people the 2nd channel (ZDF=Zweites Deutsches Fernsehen=Deuxieme Chaine Allemande) they decided to use that to their advantage in their new logo. Considering the similarity of the letter "Z" and the number "2" , they replaced the Z with the 2 and making it the 2DF from then on.
Catweazle