HUD Cover Dirt Detection via Projected Pattern Outline

The system changes the visual appearance of dirty regions by projecting a detection pattern and analyzing reflected light to identify regions where dirt blocks the projected pattern. This allows invisible or hard-to-see dirt to be visualized through optical detection, resolving the contradiction between large display area and difficulty of detecting dirty regions.

A detection pattern (intermediary element) is projected onto the exit surface to mediate between the dirt and the detection system. The pattern serves as a reference that, when blocked by dirt, reveals the location and shape of dirty regions, enabling detection on large surfaces without requiring direct visual inspection.

The system provides visual feedback by displaying the detected dirty regions on the projection display device itself. This feedback mechanism guides users to specific areas requiring cleaning, transforming the difficult task of cleaning large surfaces into a simple task of cleaning only the identified dirty regions, thus resolving the contradiction between large display area and ease of cleaning.

The projection display device performs self-diagnosis by automatically detecting and displaying its own dirty regions. This self-service capability eliminates the need for manual inspection and guides users efficiently, making the cleaning process easier despite the large surface area.