Helmut Kampfer
14Patents
5h-index
22Co-inventors
66Inventor score
Filing activity: Aug 10, 1972 → May 4, 1992
Most-cited inventions
| Patent | Title | Area | Cited by | Status |
|---|---|---|---|---|
| US3933507A | Photographic light-sensitive and heat developable material | Physics | 37 | Expired |
| US4543308A | Photographic recording process | Physics | 32 | Expired |
| US5266451A | Color photographic recording material | Physics | 7 | Expired |
| US4987063A | Gradation variable black- and -white paper | Physics | 6 | Expired |
| US5006455A | Gradation-variable black-and-white paper | Physics | 5 | Expired |
| US4483799A | Hydroxy alkane sulfonic acid sulfoalkyl esters | Chemistry; Metallurgy | 4 | Expired |
| US4636460A | Photographic recording material and process for the production of photographic images | Physics | 3 | Expired |
| US5077183A | Color photographic recording material and a process for the preparation of a photographic silver halide emulsion | Physics | 2 | Expired |
| US4504668A | Process for the preparation of N-sulfoalkyl quaternary salts of nitrogen heterocyclics | Chemistry; Metallurgy | 2 | Expired |
| US4576907A | Color-photographic recording material | Physics | 1 | Expired |
| US3951664A | Light-sensitive material having developers embedded therein | Physics | 1 | Expired |
| US4308390A | Process for the production of sulphoalkyl quaternary salts | Chemistry; Metallurgy | 1 | Expired |
| US4539408A | Process for the preparation of sulphoalkyl quaternary salts | Physics | 1 | Expired |
| US4883880A | Process for the preparation of sulfoalkyl quaternary salts and for the production of alkane sultones | Chemistry; Metallurgy | 1 | Expired |
Source: USPTO / EPO open patent data. Inventor disambiguation is heuristic; counts are objective bibliographic measures.