Display unit for fluorescent lamp deterioration

Abstract

Abstract PURPOSE: To prevent the deterioration of output picture signals by detecting automatically the deterioration of a fluorescent lamp by using a photo diode array in facsimile, etc. CONSTITUTION: Before manuscript 4 reaches read slit 5, the irradiating light of fluorescent lamp 1 is reflected from a white plate having a uniform background of slit 5 and is condensed onto photo diode array 3. Then, the output signal is obtained as a picture signal voltage at the center of each scanning period through analogue switches 8A and 8B, capacities 10A and 10B and buffer amplifiers 11A and 11B after being subjected to sample hold in 8. The output of amplifier 11A is compared with the fluorescent lamp deterioration reference voltage by 12A, and meanwhile, the output of both amplifiers is subjected to subtraction in 14 and addition in 15, and the output is compared with the fluorescent lamp deterioration reference voltage by 12B. Then, NOR is operated in 16 by both comparison outputs, so that lamp 1 can be decided to be deteriorated when LED 17 is lit COPYRIGHT: (C)1979,JPO&Japio

Inventors

• 👤 Masaru Kamimura

Bibliographic Details