Yuzo Nakano

Brightness property of micro-capsules diffuser screen in laser projection display

In recent years, the development of displays, projectors, and the like which use laser light sources have been advanced. As a laser light source is used, it provide wide color gamut and compact an optical system; on the other hand, the speckle noise is generated. We make a proposal about the microcapsule diffuser screen with the purpose of reducing the speckle noise on a laser rear projection display. This microcapsule diffuser screen has a screen surface in which microcapsules (~100um) containing charged diffuser particles are applied; where an electric field is charged from the outside and, thus, the diffuser particles in the capsule are randomly agitated to reduce the speckle noise. We have separately reported the effect of reducing speckle in relation to the driving parameters. The previous report, however, did not discuss how the configuration parameters within the microcapsule would affect the brightness, diffusion characteristics and other particulars. In this report, the authors used the Monte Carlo ray tracing method to study the diffusion characteristics of the microcapsule diffuser sheet with reference to the refractive index and diameters of the diffuser particles. The study confirmed that while the diffusion characteristics lowered with the diffuser particle diameter being 3.0μm or smaller the optical loss of the transmitting light significantly increased. Where designing the capsule profile based on the simulation model, a simple spherical profile failed to see that the actual measurement and calculated values did not agree with the other. The optical simulation model created based on a microscopic image confirmed that both values agreed. Thus, the authors confirmed that the latter was suitable for an optical simulation model.