Projector Applications Research Articles

P‐12.11: Novel, Liquid Crystal for High Performance Projector Application without Adjustment of Gamma Code, Optical and Reliability Evaluation

In this article, Novel n‐FFS liquid crystal material from Merck & JNC was used, a new type of liquid crystal JNC‐T40 with higher temperature operation with no blackening is published. The new type of liquid crystal JNC‐T40 without change the driving voltage of the original liquid crystal MLC under the condition of saving 6% compared with the current MLC. It has the similar performance in optical and reliability tests. The gamma curve from MLC 2.4 shift to JNC‐T40 2.2 shows high liquid crystal efficiency, which is significant for material saving.

High reliability and luminance of the color wheel by phosphor-in-inorganic silicone

High reliability and luminance of the color wheel in a laser light engine (LLE) employing novel phosphor-in-inorganic silicone (PiIS) fabricated at the low temperature of 180°C for laser projector applications is presented and demonstrated for the first time. Yellow (Y3Al5O12:Ce3+) and green (Lu3Al5O12:Ce3+) phosphors were uniformly mixed by inorganic silicone, organic silicone, and glass to fabricate as a phosphor color wheel. The PiIS-based color wheels showed better thermal stability than the phosphor-in-organic silicone (PiOS), about 3-7 times less lumen loss and 7-8 times less chromaticity shift under accelerated aging at 350°C for 1008 hours. The advantage of the PiIS fabricated at a low temperature of 180°C enabled the achievement of excellent thermal performance, which was similar to the phosphor-in-glass (PiG) fabricated at a high temperature of 680°C. The good thermal stability of the PiIS can be attributed to the high glass melting temperature of up to 510°C. Low-temperature fabrication, excellent optical performance, and high reliability of the proposed PiIS-based color wheels benefit as promising candidates to replace the current PiOS or PIG-based color wheels in the LLE modules for the next-generation laser projector applications.

Photon Starvation Artifact Reduction by Shift-Variant Processing

The x-ray computed tomography (CT) images with low dose are noisy and may contain photon starvation artifacts. The artifacts are location and direction dependent. Therefore, the common shift-invariant denoising filters do not work well. The state-of-the-art methods to process the low-dose CT images are image reconstruction based; they require the raw projection data. In many situations, the raw CT projections are not accessible. This paper suggests a method to denoise the low-dose CT image using the pseudo projections generated by the application of a forward projector on the low-dose CT image. The feasibility of the proposed method is demonstrated by real clinical data.

Experimental validation of axially polarized multilayer piezoelectric composite cylindrical transducers with adjustable multifrequency

The axially polarized multilayer piezoelectric composite cylindrical transducers with adjustable multifrequency capability have been proposed by adjusting the external electric resistance and the ratio of piezoelectric layer numbers between the actuator part and the sensor part, which have promising potential in designing the novel cymbal transducer for underwater sound projector and ultrasonic radiator applications. In the previous studies, the multilayer models were established to guide the design of the transducers with arbitrary layer number, and analyzed the dynamic characteristics theoretically. In this work, an experimental study is performed to validate the theoretical models and predictions. Piezoelectric rings with multiple concentric annular electrodes are designed to characterize the multilayer piezoelectric composite cylindrical transducers. The top surface of the piezoelectric rings is divided into two separate parts. One part is covered by multiple concentric annular electrodes, corresponding to the piezoelectric layers, and the other part is uncovered, corresponding to the elastic layers. Four prototypes are fabricated and each consists of four concentric annular electrodes. The impedance spectra are measured by the impedance analyzer to obtain the resonance and anti-resonance frequencies. Effects of two adjusting methods on the dynamic characteristics are evaluated experimentally. The experimental results basically coincide with the theoretical ones. This comprehensive experimental work assures the feasibility of using axially polarized multilayer piezoelectric composite cylindrical transducers with adjustable multifrequencies and confirms the benefit of the developed theoretical models for guiding the fabrication and optimization of this type of transducers.

Speckle-reduced green and yellow-green Nd:YVO4(YAG)/PPMgLN lasers for cinema exhibition industry

For exhibition industry, the application of RGB laser-illuminated projectors has already been demonstrated. However there are still some urgent scientific and technological issues to be solved. In this paper, the speckle issue of green and yellow-green all-solid-state Nd:YVO4 (YAG) / PPMgLN lasers is analyzed. We choose a well-designed multi-emitter array LD as pump sources to reduce the speckle contrast. Because the emitters of the array LD are independent of others, the speckle contrasts of the green and yellow-green lasers have been reduced to 1/24 and 1/6, respectively.

Increasing piezoelectric effect in radially polarized soft lead zirconate titanate (PZT) by pressure treating and its practical applications

Soft PZT/NAVY type II ceramic material is commonly used for underwater acoustics sensing applications due to its softer composition and higher electromechanical coupling coefficient than Navy Type I or Type III materials but can also be used for projector applications. The effective coupling coefficient (k-eff) of soft PZT hollow cylinders can be improved from 0.33 to 0.40 (20%) under axial pressure treatment and remains stable with time. The sensitivity of dielectric constant and piezoelectric modulus to compressive stress for hard and soft tangentially polarization ceramics is shown to be less than radially polarized ceramics. Effect of planar stress in spheres at moderate and deeper depths are presented. An experimental method is introduced that utilizes an air-pressurized chamber to deliver stress loads to the piezoceramic. The electromechanical properties (including k-eff, dielectric constant, piezoelectric modulus, and compliance) are measured dynamically using an impedance analyzer and resonance/antiresonance techniques. Pressure treated cylinders with improved k-eff is shown to be suitable for application that utilize pressure equalized (free-flooded) transducer designs and for air-backed transducer designs under moderate depths. The improved k-eff improves the power factor bandwidth of the transducer is further studied using equivalent electrical circuit model including the effect of external pressure.

82‐3: Red‐Enhanced Laser‐Phosphor Light Source with Quantum Dot Conversion Layer

We developed a red‐enhanced laser‐phosphor light source with quantum dot conversion layer for projector applications. This device uses dual‐layer wheel structure, in which a quantum dot layer is underneath a Ce:YAG phosphor layer. We demonstrated a high brightness and wide color gamut QD‐based light source.

Adiabatic-Molecular Dynamics Generalized Vertical Hessian Approach: A Mixed Quantum Classical Method To Compute Electronic Spectra of Flexible Molecules in the Condensed Phase.

We present a general mixed quantum classical method that couples classical molecular dynamics (MD) and vibronic models to compute the shape of electronic spectra of flexible molecules in the condensed phase without, in principle, any phenomenological broadening. It is based on a partition of the nuclear motions of the solute + solvent system in "soft" and "stiff" vibrational modes and an adiabatic hypothesis that assumes that stiff modes are much faster than soft ones. In this framework, the spectrum is rigorously expressed as a conformational integral of quantum vibronic spectra along the stiff coordinates only. Soft modes enter at the classical level through the conformational distribution that is sampled with classical MD runs. In each configuration, reduced-dimensionality quadratic Hamiltonians are built in the space of the stiff coordinates only, thanks to a generalization of the Vertical Hessian harmonic model and an iterative application of projectors in internal coordinates to remove soft modes. Quantum vibronic spectra, specific for each sampled configuration of the soft coordinates, are then computed at the desired temperature with efficient time-dependent techniques, and the global spectrum simply arises from their average. For consistency of the whole procedure, classical MD runs are performed with quantum-mechanically derived force fields, parameterized at the same level of theory selected for generating the quadratic Hamiltonians along the stiff coordinates. Application to N-methyl-6-oxyquinolinium betaine in water, dithiophene in ethanol, and cyanidine in water is presented to show the performance of the method.

Application of superpixel segmentation and morphological projector for structural changes detection in remote sensing images

Detection of structural changes in images is one of the important tasks of remote sensing (RS) data thematic analysis. The effective way to solve it is applying the Pyt'ev’s morphological projector to the pair of images of the same scene acquired on different dates. The main advantage of this method is its invariance to global brightness transformations, which in the case of RS images correspond to different parameters of the atmosphere or the different values of the brightness-contrast ratio of the scene. However, the classical Pyt'ev’s morphological projector and its regularized versions do not take into account the spatial connectivity of image samples. As a result, they ignore the textural features of images. In this article, we suggest the algorithm of structural changes detection based on superpixel segmentation and Pyt'ev’s morphological projector that takes into account local characteristics of the image pixels. In the experimental research, we analyzed the accuracies of the proposed and classical Pyt'ev’s structural change detection methods using simulated and real RS images. The comparison of two algorithms showed that the proposed method is more robust to the additive white Gaussian noise (AWGN) at different values of signal-to-noise (SNR) ratio. Additionally, the experiments with nonlinear brightness distortions (vignetting) of one of the pair of images demonstrated that the proposed method has lower false positive rates than the classical one.

32.1: Invited Paper: Q‐View: A Compression Technology for UHD Resolution, Low Power, and Low Cost LCOS Panels

Syndiant has successfully demonstrated its innovative Q‐View compression technology with the fabrication of a 4K UHD (3840x2160) LCOS micro‐display. The SYL2341 is a low‐power 0.55‐inch LCOS display for HMD and projector applications. Q‐View technology can be applied to higher resolutions beyond 4K, or to lower resolutions for significant reduction in die size and power consumption.

Laser speckle reduction utilized by lens vibration for laser projection applications

In this paper, a compact speckle reduction method utilizing vibrating lenses for laser beam scanning is proposed and demonstrated. The maximum speckle reduction efficiency was found to be 75.6% and 81.25% for a 532 nm diode-pumped solid-state (DPSS) laser and a 520 nm laser diode (LD), respectively. The minimum speckle contrast ratio observed using our method was 0.11 for the DPSS laser and 0.06 for the LD. The proposed method can provide speckle reduction with minimal power requirements, a low implementation cost, and no bending for the optical path of the laser beam. Additionally, this method is promising to withstand high-power lasers for use in high lumen laser projectors by optimizing the lens parameters. The demonstrated technique has a small form factor while simultaneously demonstrating a high degree of speckle reduction, which shows potential for speckle reduction in mini- and pico- laser projector applications.

Non‐planar projection performance evaluation and projector pose optimization

AbstractIn projector applications, the actual display effect is primarily dependent on two aspects: projector performance parameters (intrinsic properties), and projector placement (extrinsic properties). Many studies have been conducted on the impact of the original resolution, illumination, and contrast ratio on projection performance. However, few studies have focused on the influence of extrinsic properties, including the position and orientation of the projector on the projection effect. In this paper, three projection performance evaluation criteria—projection resolution, resolution difference, and projection distance difference—are proposed in terms of extrinsic properties. Based on these evaluation criteria, a projection performance evaluation function was constructed. Through this function, as well as optimization employing the multi‐start and Monte Carlo methods, projector pose parameters corresponding to optimal projection effects can be obtained. Evaluations demonstrated that the proposed projection performance evaluation criteria could correctly describe the impacts of projector placement on projection effects. Projection systems arranged according to the projector pose optimization methods achieved good performance on screens in difference shapes with different numbers of projectors, where the resolution and display improved with no change of projector hardware parameters. The optimal projector poses calculated using these optimization methods can provide theoretical guidance for practical projector placement.

Long-term stresses on linear micromirrors for pico projector application

Micro electromechanical system (MEMS) micromirrors are interesting devices to be adopted in pico projector application. In fact, together with laser sources, they can be adopted to obtain an always in focus projected image. The reliability of these devices is not yet been addressed. In this paper, we investigate the reliability of micromirrors subjected to long-term stresses. The preliminary results and their interpretation is addressed at the end of this paper. The results led us to think about two different degradation mechanisms. Permanent and recoverable stiffness variation can both influence the mechanical tilting angle of the device during long-term stresses. These two different mechanisms may affect the correct behavior of the device. Further measurements will be needed in order to validate the preliminary hypothesis made in the last section of this paper.

スライドプロジェクターと OHP を利用して演示実験を拡大して見せる(周期率)

スライドプロジェクターと OHP を利用して演示実験を拡大して見せる(周期率)

Combination of micro-scanning mirrors and multi-mode fibers for speckle reduction in high lumen laser projector applications.

In high lumen laser projectors, it is required to use laser diodes coupled to multi-mode fibers (MMFs) to obtain a high power illumination module. In this paper, we have fabricated an electromagnetic micro-scanning mirror (EM-MSM), and we have firstly demonstrated a speckle reduction method by the combination of the EM-MSM and the MMF. With the help of a condenser lens, laser beams modulated and reflected from the EM-MSM are coupled into the MMF within its acceptance angle. Because the fast scanning behavior of the EM-MSM results in the phase modulation and mode coupling among the MMF guided modes, the light intensity field distributions at the exit aperture of the MMF are changing. During the charge-coupled device (CCD) integration time, the random speckle patterns are integrated and homogenized by the CCD camera, and hence speckle is reduced. By driving the EM-MSM in raster scan, the lowest compound speckle contrast ratio at 0.0794 is obtained, where the EM-MSM half scanning angles are 0.4 ° and the optical power loss is lower than 4.5%. The demonstrated technique is compact and can endure the high power of the laser module; thus, it has a promising potential in high lumen laser projector applications.

Speckle reduction methods in laser-based picture projectors

Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

Quadrangle Detection Based on A Robust Line Tracker Using Multiple Kalman Models

Quadrangle and line tracking are essential for many real world applications of computer vision. In this paper, we propose a computationally efficient line tracker that can robustly and accurately track lines in an image. We use a multiple-model-Kalman filter (MMKF) scheme, which can handle line tracking accurately and robustly. The basic idea is to run N multiple sub-Kalman filters in parallel. Each filter is configured to use a different state transition model. All the filters are updated by the measurement at the same time following the conventional Kalman filter update process. The final prediction is a combination of outputs from all the Kalman filter modules. After lines are detected, we developed a scheme to merge the lines together to become suitable quadrangles. The experimental result shows that the proposed system can track lines and quadrangle robustly in real time. The result is useful in shape detection and should be suitable for building many mobile projector applications.

A Regulated Pulse Current Driving Technique in Green Laser Synthesis With Electrical to Optical Conversion Efficiency Improvement for Mobile Projectors

In this paper, we propose a regulated pulse current laser driver with the frequency double approach to synthesize green laser. Experiment results show that green laser synthesis conducted with the regulated pulse current driving (RPCD) technique has an electrical to optical conversion efficiency improvement of up to 78%, as compared to the DC driving technique with mean driving current of 250 mA at room temperature. This driver was fabricated with a 0.5 μm CMOS process and has a modulation frequency range of 300 kHz-700 kHz, a wide range of peak pulse current between 120 mA-900 mA with the average current range between 0 mA-280 mA. This paper not only demonstrated the synthesize procedure of green laser but also proposed driver with the RPCD technique enhances the electrical to optical conversion efficiency of green laser and its implementation in integrated circuit, making it a good match with green laser microchip to create a low cost, compact-sized device ideal for mobile projector applications.

A Robust Line Tracking Method based on a Multiple Model Kalman Filter Model for Mobile Projector Systems

Abstract Line tracking is essential for many real world applications of computer vision. In thispaper, we propose a computationally efficient line tracker that can robustly andaccurately track lines in an image. We use amultiple-model-Kalman filter (MMKF) scheme which can handle line tracking accurately and robustly. The basic idea is to run N multiple sub-Kalman filters in parallel. Each filter is configuredto use a different state transition model. All the filters are updated by the measurement atthe same time following the conventional Kalman filter update process. The finalprediction is a combination of outputs from all the Kalman filter modules. Theexperimental result shows that the proposed system can track a line robustly in real time. The result is useful in shape detection and should be suitable for building mobile projector applications.

Digital Driving Method for Low Frame Frequency and 256 Gray Scales in Liquid Crystal on Silicon Panels

A liquid crystal on silicon (LCoS) panel for projector applications is developed using a new digital driving method to increase the gray scale of the projected image without increasing the driving frequency. The LCoS panel, which has a wide video graphics array (WVGA) resolution, is fabricated using 0.18 μm CMOS process technology with an area of 9600 μm × 5800 μm. The projection system is successfully demonstrated using the fabricated LCoS panel and the proposed digital driving method. The measured results of the projection system show that the proposed driving method achieves an 8-bit gray scale at a driving frequency of 75.6 MHz, which is less than 13.7% of the frequency in previously reported methods such as frame rate control and pulse width modulation.