Pico projectors have been developing rapidly in the past few years. They have a high market potential as they could be embedded in many portable devices for large image and high resolution projection. Among the pico projector technologies, we investigated that liquid crystal on silicon (LCOS) technology could be suitable to be a pico projector by considering the manufacturing cost and the small size of projector feasibility. As the main goals of a pico projector are low cost and small size in volume, a novel space dithering algorithm was designed and investigated so that it can improve the resolution of the projection without any physical cost for a color filter LCOS pico projector and then probably reduce the whole size of a pico projector....[ Read more ]

Pico projectors have been developing rapidly in the past few years. They have a high market potential as they could be embedded in many portable devices for large image and high resolution projection. Among the pico projector technologies, we investigated that liquid crystal on silicon (LCOS) technology could be suitable to be a pico projector by considering the manufacturing cost and the small size of projector feasibility. As the main goals of a pico projector are low cost and small size in volume, a novel space dithering algorithm was designed and investigated so that it can improve the resolution of the projection without any physical cost for a color filter LCOS pico projector and then probably reduce the whole size of a pico projector.

The space dithering algorithm was designed and first investigated by computer simulations on four common and possible color sub-pixels patterns included delta RGB, mosaic RGBW, stripe RGB and stripe RGBW. Our computer simulations showed that the mosaic RGBW pattern performed better in resolution improvement compared with other color filter patterns. By using this color filter pattern, four times resolution would be improved.

The space dithering algorithm was then implemented on a 0.38” RGBW color filter LCOS (CF-LCOS) microdisplay which was made by adding RGBW pattern color filters on a 0.38” VGA color sequential LCOS (CS-LCOS) panel. The circuit driver for the 0.38” LCOS microdisplay was successfully implemented for color sequential and color filter projection separately. Also, a 0.38” QVGA RGBW CF-LCOS projector without space dithering algorithm and a 0.38” RGB VGA CS-LCOS projector were also developed and implemented for comparison. In addition, a 0.44” RGB VGA CF-LCOS projector was also found for comparison.

The results show that our proposed space dithering algorithm had a resolution improvement in both graphic and text content from QVGA to VGA. That means it improved the resolution virtually in four times. Also, the space dithering algorithm does not change the color performance compared with without this algorithm on the same panel.