Projection display apparatus

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.