Technology Used in Multimedia Projectors
Multimedia projectors are continually evolving to produce clearer, brighter images, used in theaters and bright places. Canon has developed the LCOS reflective liquid crystal panel and the AISYS optical system, focused on further improving image quality.
AISYS (Aspectual Illumination System)
A Multimedia Projector Optical System Offering Compact Size and High Image Quality
Canon mounts its own reflective liquid crystal panels, LCOS (Liquid Crystal On Silicon) in its multimedia projector image display devices.*1 LCOS panels are the ideal type of reflective liquid crystal panel for displaying high-resolution images, but they must be used with a polarization beam splitter (PBS). However, it is difficult to achieve brightness in a compact body design when using LCOS and PBS together. Canon took on the challenge of solving this problem by developing the unique Aspectual Illumination System (AISYS) optical system.
When the AISYS illumination optic system converges light from the light source, it independently controls the light in both the vertical and horizontal directions. The light is converged at a smaller angle in the vertical direction in order to prevent light leakage*2 in the PBS and LCOS, thus improving contrast. It is converged at a larger angle in the horizontal direction in order to increase brightness. This is accomplished by positioning optical elements which only act horizontally or vertically within the optical system.
AISYS has now evolved into its fourth generation.
The third generation featured a newly developed fly-eye lens,*3 with multiple lenses arranged vertically and horizontally, working together as a unidirectional convex lens. The newly developed fly-eye lens and the new optical design greatly reduced the number of lenses used, and achieved reduced size and cost while enhancing brightness and maintaining high contrast performance. In addition, the use of a projection lamp with high color rendering performance and design that took into account the sensory characteristics of the human eye enabled Canon to realize even more faithful color reproduction.
Changes in the fourth-generation AISYS include a repositioning of optical system elements, reducing color separation / combination system and overall optical system size. Thanks to these optical design refinements, in the fourth-generation AISYS, the projection lens is located 20% closer to the light source versus the third-generation AISYS, contributing to overall size reduction and brightness improvement.
- *1 Image display devices
Liquid crystal panels can be either transmissive or reflective. Since drive circuits lie between the pixels on transmissive panels, the non-transmissive parts create a grid-like pattern in the projected image. With reflective panels, the drive circuits are behind the pixels, enabling the panel to project a smooth, seamless image.
- *2 Light leakage
The leakage of light onto the image surface when displaying black.
In LCOS panels and the PBS, light beams entering at a high angle of incidence results in light leakage and reduced contrast.
- *3 Fly-eye lens
A lens composed of multiple single lenses packed closely together, both vertically and horizontally, resembling a fly's eye.
High definition video can be viewed in the CANON VIDEO SQUARE.
High-Performance Lenses with Reduced Distortion and Chromatic Aberration
Canon's UD series is a lineup of aspherical lenses with advanced optical designs and superior optical performance. As projection lenses for Canon's multimedia projectors, the UD series assures zero distortion and reduced chromatic aberration of magnification and axial chromatic aberration over the entire zooming range. The floating design / inner focus design adopted for individual lenses minimizes the quality change for images which are projected off-center near the margin of the frame.