Compact Projector Using Folded Optical Path

The patent applies dimensionality change by transitioning from a parallel arrangement of optical elements to a folded optical path using mirrors and prisms. The light path is bent at multiple angles (e.g., 45-degree mirrors, roof prisms) to fold the optical train, allowing the projection lens unit to be positioned closer to the light source while maintaining the required optical distances. This effectively converts a linear thickness requirement into a multi-dimensional folded path, reducing the projector's overall thickness.

The patent applies inversion by reversing the traditional optical path sequence. Instead of having the projection lens unit directly follow the light source in a linear fashion requiring rear space, the design uses inverted/folded optical paths where mirrors and prisms redirect light at acute angles. This allows the projection lens to be positioned in a compact configuration behind the light source while still achieving the required image enlargement and projection capability without requiring excessive rear installation space.

The patent applies the nesting principle by arranging optical elements in a compact, space-efficient configuration. The folded optical path allows multiple optical components (light source, color separation elements, projection lens) to be nested within a reduced volume. The use of right-angle mirrors and roof prisms enables the optical train to be folded back on itself, effectively nesting the optical path within a smaller envelope volume while maintaining efficient light transmission from source to projection lens.