(EN) To devise a variable magnification optical system for projection which, whilst maintaining telecentricity on the reduction side, has a simple 2-group configuration and is compact, lightweight and inexpensive, with good optical efficiency. The variable magnification optical system for projection essentially comprises two lens groups which are a first lens group (G1) which has positive refractive power which is movable when magnification is changed, and a second lens group (G2) which has positive refractive power which is movable when magnification is changed, and is configured such that the reduction side is telecentric.
(ZH) 本发明提供一种一边确保缩小侧的远心性，一边以2群结构这样简易的构成，实现小型化、轻量化和低廉化，并具有良好的光学性能的投影用变倍光学系统，和具备该投影用变倍光学系统的投影型显示装置。投影用变倍光学系统，实质上由变倍时移动的具有正光焦度的第1透镜群(G1)、和变倍时移动的具有正光焦度的第2透镜群(G2)这2个透镜群构成，且以缩小侧为远心的方式构成。
