PROBLEM TO BE SOLVED: To detect a state of liquid in a transparent tube under a mild condition as compared to a conventional configuration.SOLUTION: The state detection sensor includes a light projection section 13 for projecting parallel light to a transparent tube 11, a light reception section 14 having a photo-detector, and a liquid existence determination section 151 for determining existence of transparent liquid in the transparent tube 11 according to a result of photo-detection by the light reception section 14. The photo-detector is disposed at a position corresponding to a focal position of the parallel light projected by the light projection section 13 and transmitted through the transparent tube 11, or at a distance from a position corresponding to the focal position with respect to the transparent tube 11 when the inside of the transparent tube 11 is filled with the transparent liquid, and the photo-detector receives the parallel light which is projected by the light projection section 13 and transmitted through the transparent tube 11.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2019,JPO&INPIT【課題】従来構成に対して緩い条件で、透明管内での液体の状態の検知を可能とする。【解決手段】透明管１１に平行光を投光する投光部１３と、透明管１１内が透明な液体で満たされている場合に投光部１３により投光されて当該透明管１１を透過した平行光の焦点位置に相当する位置、又は当該透明管１１に対して当該焦点位置に相当する位置より遠方に配置され、当該投光部１３により投光されて当該透明管１１を透過した平行光を受光する受光デバイスを有する受光部１４と、受光部１４による受光結果に基づいて、透明管１１内に透明な液体が存在するかを判定する液体有無判定部１５１とを備えた。【選択図】図１
