PROBLEM TO BE SOLVED: To provide a medical X-ray photographic observation device of an edge light method which is easily made thin and light in weight and is capable of easily realizing a brightness performance stipulated by JIS-Z-4918-1995.SOLUTION: The medical X-ray photographic observation device is provided with a holding part 2 which holds an X-ray photographic film and a surface light source part 4 located behind the X-ray photographic film held by the holding part 2. The surface light source part 4 has a hot cathode tube 41, a light guide plate 40 and an electronic stabilizer for driving the hot cathode tube. The light guide plate 40 has a light incident edge surface 40a opposite to the hot cathode tube and a light emission surface 40b for emitting the light which is emitted from the hot cathode tube, is made incident on the light incident edge surface and is emitted. The electronic stabilizer has a rectification circuit part and has an inverter part which converts a direct current obtained on the rectification circuit part to a high frequency current. The inverter part has an oscillation circuit and a control circuit for controlling the action and the oscillation circuit is connected with the hot cathode tube. The electronic stabilizer is provided with a protection circuit which inputs a signal for stopping the action of the oscillation circuit when an output of the oscillation circuit becomes out the prescribed range.COPYRIGHT: (C)2006,JPO&NCIPI【課題】 薄型化及び軽量化が容易でJIS-Z-4918-1995で規定される輝度性能の実現が容易なエッジライト方式の医用X線写真観察器を提供する。【解決手段】 X線写真フィルムを保持する保持部2と、これにより保持されるX線写真フィルムの背後に位置する面光源部4とを備える。面光源部4は熱陰極管41と導光板40と熱陰極管駆動のための電子安定器とを有する。導光板40は熱陰極管と対向する光入射端面40aと熱陰極管から発せられ光入射端面に入射し導光される光を出射する光出射面40bとを有する。電子安定器は整流回路部とそこで得られる直流を高周波電流に変換するインバータ部とを有し、インバータ部は発振回路とその動作を制御する制御回路とを有し、発振回路が熱陰極管に接続されている。電子安定器は発振回路の出力が所定範囲から外れたときに発振回路の動作を停止させるための信号を制御回路へと入力する保護回路を備える。【選択図】 図3
