Semiconductor Lamp for Phototherapy
A quadrichromatic semiconductor lamp with variable colour temperature for photo therapy of seasonal disorders is described. An optimal combination of colour rendering and luminous efficacy was found by selection of commercially available semiconductor emitters. LUXEONTM LXHL series emitters with the peak wavelengths of the spectral power distribution functions at 452 nm, 520 nm, 603 nm and 645 nm, respectively, were shown to provide appreciable values of the general colour rendering index (Ra>73) in the range of colour temperatures from 3217 K to 6504 K. The 3000-lm lamp was composed of 168 high-power light-emitting diodes and a current source with pulse-width modulation. The colour temperature of the lamp is controlled by setting the durations of the light flux pulses for each group of primary emitters by an 8-bit digital circuit at a constant 2.7-ms period of the pulses. Il. 7, bibl.7 (in Lithuanian, summaries in Lithuanian; Russian and English).
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