ROAD FACE PROJECTION SYSTEM

PROBLEM TO BE SOLVED: To provide a road face projection system by which a projection image can be viewed without making an occupant of an own vehicle wear glasses or the like while suppressing that the projection image on a road face is viewed by a person existing outside the own vehicle.SOLUTION: A road face projection system 10 comprises: an on-vehicle projector 12 which projects an image on a road face in front of a vehicle by near infrared light; a front window 13 in which a polarization control element 13a which functions as a quarter wavelength plate in a period of the application of a voltage, a polarization beam splitter 13b, and a wavelength conversion element 13c which converts near infrared light to visible light are laminated on one another from the outside of a vehicle, and which is switched to a state that the near infrared light permeates the polarization beam splitter by voltage control, or to a state that the near infrared light does not permeate the polarization beam splitter; and a control part 14 which pulse-oscillates the near infrared light when performing image projection by the near infrared light, and makes an oscillation cycle of the near infrared light and a permeation cycle of the near infrared light in the polarization beam splitter synchronized with each other by the voltage control applied to the polarization control element.SELECTED DRAWING: Figure 6 【課題】自車両の外にいる人に路面上の投影画像が見えることを抑制しつつ、自車両の乗員が特殊なメガネ等を装着しなくても投影画像を見ることができる路面投影システムを提供する。【解決手段】路面投影システム１０は、車両前方の路面に近赤外光による画像を投影する車載プロジェクタ１２と、電圧印加期間に１／４波長板として機能する偏光制御素子１３ａと、偏光ビームスプリッタ１３ｂと、近赤外光を可視光へ変換する波長変換素子１３ｃとが車外側から積層され、電圧制御によって近赤外光が偏光ビームスプリッタを透過する状態と、近赤外光が偏光ビームスプリッタを透過しない状態とに切り替わるフロントウィンドウ１３と、近赤外光による画像投影を行う際に近赤外光をパルス発振させ、偏光制御素子に対する電圧制御によって、近赤外光の発振周期と、偏光ビームスプリッタにおける近赤外光の透過周期とを同期させる制御部１４とを備える。【選択図】図６