DIFF Subgroup
H04R 21/02 Microphones
Introduced: September 1968
Full Title
Full titles differ between systems:
IPC:
Variable-resistance transducers > Microphones
CPC:
Variable-resistance transducers (gaseous resistance transducers H04R23/00; magneto-resistive transducers H04R23/00) > Microphones
Of 5 combined children, 0 exist in both systems.
5 codes are CPC-only extensions.
Child Classifications
Navigate with arrow keys, Enter to open