I have a claim similar to:
the display of claim 1 wherein the image displayed is modified by at least one of:
- the image is brightened by increasing the voltage,
- the image is brightened by switching to the second polarization,
- the image is darkened by reducing the voltage or
- the image is darkened by switching to the first polarization.
If I understand correctly, this "at least one of a, b, or c" structure means it could be a, b, c, ab, ac, bc, or abc (i.e. any combination of a, b and c).
The process should be able to do any combination of 1 and 2 or any combination of 3 and 4 (choosing to do 1 or 2 ways to brighten an image at the same time or 1 or 2 ways to darken it).
The fact is, at different times you would want to do different things (e.g., in bright daylight you are more likely to want to brighten and at night you might be more likely to darken). So the clause was intended to list the ways we brighten or darken without muddying legal waters.
THE QUESTION: Could an examiner or potential infringer claim that since one of the combinations couldn't work AT THE SAME TIME (in this "any combination of" structure), like 1 and 3, that the claim was invalid because one of the combinations wouldn't work?
If the answer is "yes", what's a better approach without paying for a plethora of dependent claims?