| 摘要 |
A fluorescent X-ray viewer includes a photosensor within the housing proximate to the fluorescent lamps for detecting the intensity of the light prior to transmission through the X-rays or other transparencies to be viewed. A dimming circuit is used to adjust the intensity of the fluorescent lamps to less than the nominal value, and feedback through the photosensor is used to maintain the light intensity output at a substantially uniform level to compensate for line and load variations and aging and changes of the efficiency of the fluorescent lamps. The X-ray viewer is provided with an LED warning indicator which is energized when the lamps have deteriorated to an extent which requires replacement.
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