Michael Ansorge, Pierre-André Farine, Patrick Stadelmann, Steve Tanner
The presentation reports upon the conception and realization of a miniature very low-power microcamera system that has been embedded in a wristwatch so as to enable the spontaneous capture of photographs in everyday life based on timekeeping devices the users would naturally wear. The designed microcamera system is fully operational and incorporates specific optics and a color VGA format based image sensor, a viewfinder enabling the selection of the scene to be captured, an image preprocessing step for color interpolation and white/color balance, followed by a dedicated JPEG compatible still image compression algorithm producing fixed-sized encoded images. Finally, the user is given the possibility to screen a posteriori (postview mode) the set of images captured, e.g. to erase less interesting ones in order to liberate the corresponding storage space. The user interface is composed of a particular display usually indicating the time, that is switching into a camera management mode for the acquisition and postview of photographs. Moreover, the camera can communicate with a personal computer through a cradle either to download the set of photographs acquired, or to upload a set of operational parameters, while simultaneously reloading the accumulator supplying the microcamera of the wristwatch. The technological challenge induced by the dense integration requirement of the numerous peripheral devices, including the central processing capabilities, the user and communication interfaces, and the tight power consumption constraints to be fulfilled, ask for the elaboration of numerous innovative solutions out of which only few were published so far. The purpose of the presentation is to provide insight into the system organization and its breakdown into original inter-playing hardware and software components, which were finally validated by the realization of an industrial prototype and demonstrator. The multi-fold experience collected by the partners in the design proce- ss is of course nurturing further activities, and, from a didactic viewpoint, offered the opportunity to set up practical laboratories that were dispensed in the realm of the Summer Schools Highlights in Microtechnology coordinated by the European Associated Laboratory (LEA) and more recently funded by the EU FP6 Marie Curie programme.
2007
