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FRAUNHOFER INSTITUTE FOR PHOTONIC MICROSYSTEMS IPMS 2 1 1 Ultra compact projection 3 LASER PROJECTION MODULE module. 2 Concept of projection head with two 1D scanners. 3 LinScan MEMS scanning mirror. Introduction to the human eye appears. The scanner mirrors typically have a diameter of about Pico-projectors are considered the ultimate one millimeter and are manufactured Fraunhofer Institute for feature of future mobile telephones: Projec- from micro-crystalline silicon wafers with Photonic Microsystems IPMS tors so small that they can be integrated established processes in cost-effective lots into the mobile device. At present a projec- in the Microsystems technology clean room Maria-Reiche-Str. 2 tion the size of a television screen seems at Fraunhofer IPMS. 01109 Dresden possible from a short distance, and HD resolution is also in demand. Contact System architecture Dr. Michael Scholles Fraunhofer IPMS has already been active for Phone +49 351 8823-201 a few years in making customer solutions The laser projection system consists of [email protected] for pico-projectors available. The Institute the laser sources plus optics, the micro has been focusing on the principle of scanning mirror and system electronics laser beam steering for image generation. (see block diagram in fig. 3). The laser Just like a CRT in which an electron ray beam is collimated and directed onto the is deflected so that it stimulated one scanning mirror. Three different mirror image point after the other to light up, types are possible which have an influence one brightness-controlled laser beam (or on the way the image generated in detail. three in red, green and blue for full-color First type are bi-resonant mirrors with Quality Management display) is directed so quickly over the sinusoidal oscillations of the mirror around We are certified projection surface by a single miniaturized two perpendicular axes, a Lissajous figure Voluntary participation in regular monitoring according to ISO 9001:2008 scanner mirror that an image cohesive is projected onto a screen. By carefully www.ipms.fraunhofer.de ISO 9001:2008 n A C erti fica ti KR o DE ce rtified laserprojektionsmodul-e SPI-Flash DVI-D Analog Video DVI to RGB Video Processing Gdigital FPGA Implementation Bdigital AV to RGB RGB Digital DAC DAC Red Laser DAC Green Laser Blue Laser QDR-SRAM Power Unit 12 V Power Supply 4 Rdigital USB Position Detection USB 2.0 Mirror 4M x 18 200 V 3.3 V Position Detection 1.2 V, 1.8 V, 2.5 V, 3.3 V, 5 V 5V Scandrive-Chip choosing the frequency ratio for the two at Fraunhofer IPMS make advanced system Path to higher resolutions is set by the axes it can be ensured that the laser beam parameters (SVGA, i. e. 800 x 600 pixels new quasi-static scanner concept from hits every virtual pixel of the image grid and 60 fps) possible. The control circuit also Fraunhofer IPMS called LinScan. The basic overlay of the Lissajous pattern within the provides SVGA resolution. Support of grey technology doesn’t have to be changed, so time available for a given frame rate. By scales with 8 bit resolution per pixel and that our customers continue to profit from synchronous modulation of the laser source elementary color as well as the correction the seasoned manufacturing process. It is and driving of the mirror, arbitrary images of inhomogeneous illumination caused by sufficient to tilt the actuator combs toward can be projected. the varying beam speed in different parts each other permanently with a final micro- of the projection area are integrated in the assembly step, along with a small modifica- control unit. tion of the mechanical design. The Institute The demonstrators allow a direct connection with any standard analog or digital was able to show that a combination of video source, no special software to control The electronics accepts video data in digital resonant actuator on the quick horizontal the projector is required. Necessary adjust- form via DVI-D as well as analog signals. axis and LinScan on the slower vertical axis ments can be made directly. For backward compatibility with previous is possible for a two-dimensional scanner systems also sending data via USB 2.0 from like those necessary for pico-projectors. The a PC running a special control application laser beam can now make targeted jumps is possible. from line to line according to an externally Technical Parameters configured frequency. Pico-projectors with The bi-resonant micro mirrors used in full Figure 1 shows a module for monochrome a SVGA resolution (800 × 600) and higher featured laser projection demonstrators red image projection that comprises the will be easily practicable. achieve oscillation amplitudes of about laser, the micro optics and the micro 10° (fast axis) and 12° (slow axis) at driving scanning mirror. It has a volume of only voltage of 70 V and at normal pressure 17 mm x 7 mm x 5 mm. Full color capable with open-loop control. In order to cope systems still have larger dimensions. with long-term environmental changes, a Image projection closed-loop operation with position detection is required. Analog signal processing Applications Alternative Approaches is handled by the special Scandrive chip Rear projection Laser labeling that also features generation of voltage The second type of micro mirrors for laser pulses for driving the mirror. The oscillation projection also uses the Lissajous pattern frequencies of the available micro mirrors approach. However, instead of using a of about 1.2 kHz (slow axis) and 28 kHz single two-dimensional MEMS scanning (fast axis) allow a resolution of up to 640 x mirror, the projection head comprises two 480 pixels (VGA resolution) and refresh 1D mirrors. Figure 2 shows a drawing of rates of up to 50 Hz. Recent developments the projection head. Various exposure purposes 4 Block diagram of system electronics for laser projection module.