Patent ID: 8777426

Claim:
A projection type display comprising: an optical system including a focus lens and configured to project an image formed by an image modulator to a projection surface; a driver configured to move the focus lens along an optical axis with respect to the image modulator and the projection surface; a phase difference sensor configured to receive light of the image that has been projected; and a controller configured to calculate an in-focus position and to move the focus lens via the driver to the in-focus position for a focus control of the optical system, wherein in a case that, in a movable range of the focus lens along the optical axis, a part of the movable range where a blur of a projected image falls within a predetermined range even when a projection distance changes is defined as an allowable range, the controller, when the focus lens is located outside the allowable range, moves the focus lens to a predetermined position within the allowable range, and then calculates the in-focus position based on an output of the phase difference sensor to move the focus lens to the in-focus position.