Hannu,
This is definitely not a logo you'd see often.
I could have sworn I saw it in one of my German catalogs, good thing I didn't
Wasn't able to find it yet.
Now I don't know where or when I saw this logo, maybe got confused with other German manufacturers with woman's face like Orion, Ernemann, Wunsche.
As far as dating it...
Well, it most likely a pre-1924 model (finder in the center).
Post 1914 (Weeka was established then).
Several features which are not often found on Welta cameras: early lily-shaped strap attachments, rare spring for the strut, outward-curved pull-out wings. I'd say it's close to 1920 +/- 3 years. Could be one of the Weeka's Welta models, haven't seen those though.
I'll keep an eye on the logo.
Eugene.