Wrinkle formation in conformable liquid crystal cells for use in a contact lens display

Wrinkle formation in conformable liquid crystal cells for use in a contact lens display was investigated. Smooth cells with minimal thickness were obtained when using an asymmetric configuration with a thin layer at the convex side and a thicker but threshold dependent layer at the concave side

Design and wrinkling behavior of a contact lens with an integrated liquid crystal light modulator

A new design of a spherically molded liquid crystal cell intended for embedding in a contact lens is proposed. Wrinkle formation in these cells was investigated and a correlation was found between the total thickness of the cell and its smoothness. Smooth cells with minimal thickness were obtained by using an asymmetric configuration with a thin layer at the convex side and a thicker but threshold dependent layer at the concave side. Active liquid crystal cells filled with a guest-host liquid crystal mixture exhibited uniform light modulation along their surface, paving the way towards a modulation-based contact lens display

Micromirror with electromechanical pulse width modulation

A novel micromirror design is presented that can be used as a pixel in a light valve. This mirror allows grey levels to be produced without the need for binary subframes. Analog pulsewidth modulation (PWM) will be achieved without needing extra transistors in the CMOS layer below the mirror structure. This can be done by exploiting an electro-mechanical phenomenon known as ‘pull-in’. It will be shown that it is possible to make the mirror switch from a positively tilted to a negatively tilted state and back with a duty ratio that is dependent on fixed voltages on two out of four addressing electrodes underneath the mirror. The other electrodes are driven with two independent triangular waveforms. The mirror thus performs an analog to PWM conversion at the MEMS level, not at the CMOS level. The number and the distribution of grey levels does not depend on the number of binary subframes or bitplanes, resulting in less severe speed requirements for the on-chip electronics

Spherically curved guest-host display for use in a contact lens

A spherically curved cavity filled with a dichroic dye doped liquid crystal was made using flexible LCD processing techniques in order to create a contact lens display technology. Processing issues are described and their influence on uniformity and contrast are discussed

Novel analog pulse-width-modulated 15-μm SiGe micromirrors

A novel six-electrode SiGe micromirror pixel enabling analog pulse-width modulation (PWM) in display applications is presented. Instead of utilizing bitplanes, arbitrary duty cycles can be realized, resulting in an analog gray-level distribution. This eliminates the posterization (contouring) effect that is typical for digital micromirrors. Moreover, the pixel design does not require the incorporation of electronic comparators and the gamma compensation can be processed externally. Two out of the six electrodes are used as landing electrodes. The other four attracting electrodes are driven by two anti-phase saw-tooth signals and two fixed analog voltage signals. By applying this signal scheme, the duty cycle of the mirror is modulated in an analog manner. Test vehicles were manufactured where SiGe is the microelectromechanical systems (MEMS) material. The use of SiGe as a structural layer is advantageous to build MEMS since the CMOS and MEMS layers can be deposited in a monolithic manner. Measurements using a Laser Doppler Vibrometer (LDV) have confirmed the feasibility of analog PWM for 15-μm SiGe micromirrors