Analog clock with hidden time display that selectively becomes visible according to the position of the hour and minute hands.

Abstract

The invention relates to a passive optical display system that enables the time indicators on the dial (1) of mechanical or analog clocks to be concealed in such a way as to be indistinguishable from the dial background (16) under ambient light and to be made visible only depending on the position of the hour (17) and / or minute hands (18). In the system, the hour (17) and minute hands (18) are arranged in a light-guided optical structure comprising a light-guided hand body (19) that collects ambient light and transmits it to the tip of the hand (24), a hand optical core (20), a hand light-gathering surface (21), a microprismatic / diffractive light input structure (22), and a hand reflective side surface / optical boundary surface (23). The guiding optical output (25) at the tip of the hand couples the transmitted light only to the display input area / optical coupling input (11) of the aligned concealed hour indicator / hour index (9) or concealed minute indicator / minute line (10).The dial (1) indicators are formed not as visible paint or print on the surface, but as optical receiver-emitter structures within the embedded optical indicator layer (7) located under the upper decorative dial layer (3). Sunlight or office light from above is limited by an optical masking layer (4), an angular selective optical limiter layer (5), or a micro-louver / micro-louver structure (6) so as not to activate the indicators. When the local light from the pointer is coupled to the relevant indicator via the indicator input region / optical coupling input (11), the light is carried along the internal micro-light guide (12) and emitted through the micro-scatter structure (14) and wide-angle light emission region (15) via the indicator output region (13), making only the relevant time information visible.

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