Patent ID: 7052140

Claim:
An illumination device, comprising: a light-emitting tube including a light-emitting portion to emit an illumination light; an elliptical reflector having respective focal points in a vicinity of a location of the light-emitting portion of the light-emitting tube and further in an illuminated region from the location of the light-emitting portion; a parallelizing lens to make parallel the illumination luminous flux outgoing from the elliptical reflector; a first lens array in which small lenses having a flat rectangular shape, which split the illumination luminous flux parallelized with the parallelizing lens into a plurality of partial luminous fluxes, are arranged as a matrix composed of 6 rows and 4 columns in a longitudinal direction and lateral direction, respectively; a second lens array having a lateral width less than a lateral width of the first lens array and setting each partial luminous flux, split by the first lens array, parallel to an optical axis of the device; and a polarized light conversion element to convert each partial luminous flux outgoing from the second lens array into a partial luminous flux having a polarization axis in a prescribed direction, the polarized light conversion element includes: a first polarized light separation unit composed of a single polarized light separation surface to transmit the partial luminous fluxes having polarization axes in one direction and to reflect the partial luminous fluxes having polarization axes in other directions with respect to partial luminous fluxes of two rows, a first row and second row, of the second lens array and a single reflecting surface to further reflect the partial luminous fluxes having polarization axes in other directions that were reflected by the polarized light separation surface and to arrange them in a direction parallel to the partial luminous fluxes having polarization axes in the aforementioned one direction; a second polarized light separation unit which has a configuration with a left-right symmetry with respect to the first polarized light separation unit and is composed of a single polarized light separation surface to transmit the partial luminous fluxes having polarization axes in one direction and to reflect the partial luminous fluxes having polarization axes in other directions with respect to partial luminous fluxes of two rows, a third row and a fourth row, of the second lens array and a single reflecting surface to further reflect the partial luminous fluxes having polarization axes in other directions that were reflected by the polarized light separation surface and to arrange them in a direction parallel to the partial luminous fluxes having polarization axes in the aforementioned one direction; and a phase difference plate disposed in either a transmission region of the partial luminous fluxes having polarization axes in the one direction or a transmission region of the partial luminous fluxes having polarization axes in the other direction.