Projection systems have been used for many years to project motion pictures and still photographs onto screens for viewing. Image projection systems using multimedia projection systems have become popular for conducting sales demonstrations, business meetings, and classroom instruction. Projection-type display apparatuses capable of projecting an enlarged image from a personal computer modulates an output light from a light-source lamp using a light valve such as a liquid-crystal display panel based on an image signal, and enlarges and projects the modulated light image on a projection screen through a projection lens. The image projector typically includes a lamp module removably housed inside the image projector. The light source typically includes a replaceable lamp module for generating and directing light toward the image-forming device before it is projected onto the screen. Various types of projectors, such as overhead and LCD projectors, include a lamp, that is, a light source such as an incandescent or quartz bulb, that enables the projection of images onto a screen. In order to produce adequate light intensity, the lamp module includes a light source which may be, for example, a metal-halide or other type of arc lamp, an incandescent lamp, or a fluorescent lamp. a metal halide lamp, A xenon lamp, and a high-pressure mercury lamp may be used as a light-source lamp for the projection-type display apparatus. These light-source lamps emit a relatively stable light for a few thousand hours. Arc discharge lamps have been widely used in fixed and portable projectors because of the ability of arc discharge lamps to produce high intensity light. High-pressure mercury vapor discharge lamps have a high luminance and therefore utilized for a light source of such optical devices as a liquid crystal projector, with the lamp being positioned so that the light emitting region (arc) is located at the focal point of a reflector mirror such as a parabolic mirror. Typical image projection lamp assemblies include a lamp located within a reflector. This assembly is usually positioned within the projector housing near the projection engine by a ceramic collar to which the reflector is attached. The lamp used in projection display systems requires periodic adjustment for optimum light distribution on the display screen and for maximum overall brightness of the projected image. Careful alignment and orientation of the lamp within the optical projection system is very important to obtaining bright and well-defined projected images.
