| # | Country | Total Patents | |
|---|---|---|---|
| #1 | France | 11 | |
| #2 | United Kingdom | 2 |
| # | Industry | |
|---|---|---|
| #1 | Audio-visual technology | |
| #2 | Electrical machinery and energy | |
| #3 | Telecommunications | |
| #4 | Basic communication technologies |
| # | Technology | |
|---|---|---|
| #1 | Loudspeakers and microphones | |
| #2 | AC and DC conversion devices | |
| #3 | Advertising | |
| #4 | Transmission | |
| #5 | Amplifiers |
| Publication | Filing date | Title |
|---|---|---|
| GB311755A | Improvements in or relating to thermionic valve amplifiers | |
| GB310490A | Improvements relating to sound reproducing apparatus or loud speakers |