Patent ID: 7618156

Claim:
A light irradiation device comprising an LED that irradiates light forward, an optical unit that makes an engagement with the LED with their axial lines aligned with each other by approaching the LED from the front side of the LED, a tubular first housing element having an opening at its rear end surface for inserting the optical unit, the LED and a thermal conduction member to be tightly attached to a rear surface of the LED into the inside of the first housing element in this order, a deciduous inhibition member that makes an engagement with a vicinity of the opening of the first housing element and that prevents the optical unit, the LED and the thermal conduction member that have been inserted into the first housing element from dropping off, a second housing element that blocks up the opening by being mounted on a predetermined position of the first housing element and that forms a housing together with the first housing element, and a projecting member that is arranged on the second housing element to project forward, wherein, at the predetermined position, the projecting member presses the rear surface of the LED through the thermal conduction member to engage the optical unit and the LED, thereby to align their axial lines.