The following is the graph comparing the number of granted patents per IPC section among Japan, the United States and Europe(EP) in the past 20 years.
(IPC:International Patent Classification)
A: HUMAN NECESSITIES
B: PERFORMING OPERATIONS; TRANSPORTING
C: CHEMISTRY; METALLURGY
D: TEXTILES; PAPER
E: FIXED CONSTRUCTIONS
F: MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
As shown above, United States has the largest number of granted patents in three countries , especially in the classification sections of G(PHYSICS) and H(ELECTRICITY).
However, there are more patents in Japan than in US or EP in the sections about B(PERFORMING OPERATIONS; TRANSPORTING),D(TEXTILES; PAPER),E(FIXED CONSTRUCTIONS).
Then the Japanese patent search and analysys in these field particularly seems to be important in order to grasp and understand the prior arts or invalidate the certain patent.
It should be noted that the above data are only registered patents and there are more patent applications in three.