PROBLEM TO BE SOLVED: To provide a light energy time-sharing distribution apparatus, a plant factory, a building, a light energy time-sharing distribution method, and a rotating cylinder which can distribute light energy in a time division fashion at high speed with a simplified apparatus structure while suppressing influence of heat generation.SOLUTION: A light energy time-sharing distribution apparatus 20 according to an embodiment includes: a rotating cylinder 1 that has an outer peripheral surface 3 and rotates around a central axis as a rotation axis, the rotating cylinder 1 having the outer peripheral surface 3 comprising a first reflection surface 4a that reflects an incident light entering from one direction in a first direction 7a and a second reflection surface 4b that reflects it in a second direction 7b； a first reflected light guide path 13a that guides the light reflected in the first direction 7a to a first illumination range 15a； and a second reflected light guide path 13b that guides the light reflected in the second direction 7b to a second illumination range 15b. A shape of a section that is perpendicular to the rotating axis in the first reflection surface 4a and the second reflection surface 4b includes a part of a logarithmic spiral curve 9 centered at the rotation axis.SELECTED DRAWING: Figure 4【課題】発熱の影響を抑えつつ、装置の構造を簡素化し、光エネルギーを高速で時分割分配することができる光エネルギー時分割分配装置、植物工場、建築物、光エネルギー時分割分配方法及び回転筒を提供する。【解決手段】実施形態に係る光エネルギー時分割分配装置２０は、外周面３を有し中心軸を回転軸として回転する回転筒１であって、一方向から入射する入射光を、第１方向７ａに反射する第１反射面４ａ及び第２方向７ｂに反射する第２反射面４ｂを含む外周面３を有する回転筒１と、第１方向７ａに反射された光を、第１照明範囲１５ａに導光する第１反射光導光路１３ａと、第２方向７ｂに反射された光を、第２照明範囲１５ｂに導光する第２反射光導光路１３ｂと、を備える。第１反射面４ａ及び第２反射面４ｂにおける回転軸に直交した断面形状は、回転軸を中心とした対数螺旋曲線９の一部を含む。【選択図】図４
