Projection type image display devices are applied to large-scaled projection televisions and widely being used as a device that receives an image signal from the outside, enlarges the image, and projects the image onto a panel, a wall surface, or the like as disclosed in Patent Document 1. In recent years, the projection type image display devices are also expected as a device capable of easily projecting, for example, an image obtained by a mobile terminal such as an iPhone or an iPad mini onto a wall surface, a surface of a desk, or the like in addition to display of an image signal from a personal computer (PC). A projection lens system including a reflective mirror (a free-form surface mirror) or a free-form surface lens for this is disclosed in detail in Patent Document 2.
USPTO Backgrounds
USPTO Backgrounds