https://patentbrief.org/company/central-investment-corp Plain-English explanations of patents assigned to Central Investment Corp, newest first. en-us Sat, 13 Jun 2026 10:12:27 GMT https://patentbrief.org/patent/us/3735375/smoke-detector-ionization A 1973 circuit design using a vacuum tube to detect microscopic resistance shifts in sensors like ionization chambers, commonly used in early smoke detectors. Tue, 22 May 1973 00:00:00 GMT https://patentbrief.org/patent/us/3735375/smoke-detector-ionization