CRT displays [was: computer graphics in the 1950s]

Christian Corti cc at
Sat Oct 25 07:11:55 CDT 2008

On Fri, 24 Oct 2008, der Mouse wrote:
>> I just want to mention that there were polar-coordinate tubes.
> Wow.  I can't even imagine how I'd build a deflection system that
> worked in polar coordinates.  Do you happen to know anything about how
> the deflection worked?

I've never seen such a tube in any equipment myself, but there is a very 
interesting (German) discussion on the RCA 3DP1 polar-coordinate tube:
Nonetheless I recommend having a look at this link as there are great 
pictures from the tube including pinout, data and photos from a 
disassembled tube.

This particular tube has four deflection plates as in an ordinary 
electrostatically deflected tube. You apply a sine/cosine voltage to the 
plates to create a circle. But additionally there's a needle at the center 
of the screen used for the polar deflection.

Maybe there is more information in the patents 2328259 (Polar 
coordinate cathode-ray tube, 1943) and 2864033 (Polar coordinate tube, 
1958), both found on, but the site seems to be 
non-functional at the moment.


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