Patent ID: 7185990

Claim:
A projection display apparatus for expanding and projecting an image, which is formed by an optical modulator, using a projection lens comprising: a light source for illuminating the optical modulator; a first lens array for dividing light emitted from the light source into a plurality of partial luminous flux; a second lens array for superimposing the plurality of partial luminous fluxes emitted from the first lens array onto the optical modulator; and a diaphragm mechanism, which is disposed between the light source and the optical modulator, for controlling an amount of light from the light source, wherein a traveling direction of the light emitted from the light source is defined as a Z-axis, a direction perpendicular to the Z-axis is defined as an X-axis, and a direction perpendicular to a plane formed by the Z-axis and the X-axis is defined as a Y-axis, wherein an area of an opening of the diaphragm mechanism changes in a direction of the X-axis or the Y-axis, wherein the diaphragm mechanism has a diaphragm blade or a pair of diaphragm blades both of which are positioned in the Y-axis direction with an interval, wherein areas of respective plural lenses included in the first lens array or the second lens array, which are light-shielded by a side-portion of the opening of the diaphragm blade or each of the pair of diaphragm blades, include different light-shielded areas, wherein the diaphragm blade or each of the pair of diaphragm blades has a shape in such a manner that illuminance is substantially uniformly changed at a plane where the light emitted from the light source is projected while the area of the opening of the diaphragm mechanism changes wherein the image formed by the optical modulator has a rectangular shape, and a short side direction of the rectangular shape of the image corresponds to the Y-axis, and the side-portion of the opening of the diaphragm blade or the each of the pair of diaphragm blades has a stepwise shape and a width along an X-axis light-shielded by each step of the stepwise shape corresponds to a width along the X-axis of respective one of the respective plural lenses.