Transcript 675 nm
Mirasol Displays MAE 268 Erik Bettis Josh Saylor Introduction • MEMS device developed by Qualcomm – Low power display • Uses ambient light as source • Operation requires very low voltages – Replacement for current LCD screens • Cell phones and other small devices – Enhance viewability in direct light • Brightness of display increases as ambient light intensifies • Light reflection of up to 50% Erik Bettis Current Products Hisense C108 Handset Inventec V112 Smartphone G-Core Mini Caddy Erik Bettis Mirasol Technology • • • • Interferometric Modulation (IMOD) Low power consumption Increased readability in direct light Bistability – Hysteresis – Built in Memory • Pixels – Color Generation • Interference • Spatial Dithering Erik Bettis Interfermetric Modulation (IMOD) • Enables reflective, direct view and flat panel displays • Refresh rates on the order of microseconds – Video-rate capable • Contrast Ratio: >15:1 • Reflectivity: ~ 50% • Wall Street Journal – Contrast Ratio: 4:1 – Reflectivity: ~ 60% Erik Bettis Power Metrics • Mirasol IMOD Display vs. TFT LCD Displays Video Time Typical Use Multi Media Use 4.5 Hours 206 min 160 min 3.3 Hours 70 min 24 min Erik Bettis Increased Readabilty Erik Bettis What is Bistability? • Main feature of Mirasol devices that allows for low power consumption. • Allows for pixels to be left on or off with near-zero power drain. – Uses imbalance between electromechanical forces and mechanical forces to hold membrane in place with very low power. • Provides built in memory for pixel placement Erik Bettis Hysteresis • Stage 1 – Constant bias voltage holds membrane in open state • Stage 2 – Positive pulse applied to drive membrane into collapsed state • Stage 3 – Constant bias voltage holds membrane in collapsed state • State 4 – Negative pulse applied to snap membrane back to open position Erik Bettis Bistability and Hysteresis in Mirasol Erik Bettis Pixel Design and Color Generation • Pixels create patterns of Red, Green and Blue to create 256k color range – Interference • Reflects different wavelengths to create different colors – Red: λ = 675 nm – Green: λ = 520 nm – Blue: λ = 450 nm – Dithering • Meshes different amounts of Red, Green and Blue to create new colors – Similar to mixing paint colors on the nano-scale Josh Saylor Examples of Spatial Dithering Colors as Assigned Color perceived Josh Saylor Interference Josh Saylor Proposal of New Design Advantage: Analog mirror control allows for multiple colors from a single unit Blue: 450 nm Green: 520 nm Red: 675 nm 50 μm Glass Thin Film Electrode Pull in distance (450 nm) Rigid SiO2 Support Mirror Analog operating region (225 nm) Spring Si substrate Side Profile (not to scale) Josh Saylor Spring Fabrication Spring can easily be machined by standard surface micro-machining procedures SiO2 Support Spring Material Compressible Design 0V Josh Saylor Pull In Voltage and Spacing Values Used Max Voltage = 5 V Permittivity = ε0 = 8.85x10-12 F/m Mirror will collapse against thin film at 5 Volts Area = (50 μm)2 = 2.5x10-9 m2 Initial spacing = 675 nm Fpull-in = = 1.4x10-6 N k = Fpull-in / Δxspring = 6.1 N/m Vpull-in = =5V Josh Saylor Pixel Design of New Layout 100 μm 350 μm New Design 4 units per pixel Current Design 42 units per pixel One color per unit Temporal and Spatial dithering still possible Resolution Scaling Factor of 10 The old 1.4 inch display with 176 x 144 resolution would increase to 1760 x 1440 pixels with new design Josh Saylor Questions