As the performance of solid state light-sources, such as light-emitting diodes (LEDs) is rapidly improving, while prices are dropping, new applications for solid state light-sources are emerging. For some applications, where the maximum luminance is a key feature, LEDs, however, have not yet been widely adopted. Due to thermal management issues and the so-called droop, the loss of efficiency at excessive drive current densities, currently available LEDs still cannot meet the requirements on high luminance over time for, for example, automotive headlamp applications without rather complex and costly thermal management arrangements, such as large cooling fins and/or fans. The same is valid for other applications, such as for spotlights etc.
In addition, for automotive headlamps as well as for spotlights etc, it would be desirable to be able to control and change the illumination pattern electronically. For example, in the case of an automotive headlamp, it would be desirable to be able to control the illumination configuration depending on the driving conditions. Systems to achieve this, often referred to as Advanced Frontlighting Systems (AFS), exist. For instance, LED-based AFS-headlamps have been proposed, which are realized using an array of addressable LEDs, so-called pixel light.
Such an arrangement is, for example, disclosed by U.S. Pat. No. 7,429,918, where a number of LEDs are each arranged on a separate substrate, and each substrate can be individually controlled to a selected inclination angle. Hereby, various illumination configurations can be achieved, but with a complex arrangement having many moving parts that have to be individually controlled. Furthermore, heat management issues still remain to be addressed.