| 摘要 |
1280494 Measuring ultraviolet radiation DETEC S A 4 Aug 1969 [5 Aug 1968; 4 June 1969] 38924/69 Heading G1A To measure the intensity of ultraviolet radiation emitted by a U.V. tube in a narrow band of wavelengths including 2537A, which intensity is indicative of the germicidal efficiency of the tube 1, a filter 3 for passing only the above wavelength band is situated between the tube and a photo-cell 4 whose output is fed to a threshold device including a signalling device 7. As shown in Fig.1, a shutter 2 is placed between the tube and one or more interference filters 3, the shutter ensuring that light is incident on the photo-cell only when it is desired to make an intensity measurement. In the embodiment of Fig.2, the shutter movement is controlled by a relay 10, and with the shutter open, when the intensity of light in the narrow wave band is below a predetermined level transistor 5 becomes conducting. Thus, relay 14 closes contact 15, causing operation of multivibrator 6. In this way, neon lamp 7 flashes intermittently when the radiation intensity is below a predetermined level. Alternatively, indicator 7 could give acoustic signals. In further embodiments Figs.3 and 4 (not shown) the circuitry is modified such that the neon lamp flashes when the radiation intensity is above a predetermined level, which level may be adjusted using a potentiometer (77). The single photo-cell may be replaced by a plurality of photo-cells connected in parallel. |
