Exactly, PIR motion detector was design to catch only moving target.
After reading this very informative article:
I'm thinking, all it takes is to hack cheap PIR, so it'd able to detect unmoving object as well -):
But the same time I understand, due PIR sensor limits on spectral recognition of the radiation it detects, it will never works. It can't see difference between warm or/and small object in front of it,
or very hot or/and big object far away.
Probably thermo-cam plus analytical algorithm of the image is only option
to design something reliable.
One question, if it for clock, what the point make it works for unmoving person?