Liquid Crystal Panel Research Articles

Integral imaging systems using interleaved Fresnel lenses and transmissive display panels

Integral imaging reproduces the light-ray space of a scene to realize a 3D vision. In particular, a coarse integral imaging system, featuring elemental lenses large enough to cover more pixels than the number of views, holds promise in applications like interactive visualization systems and automobile head-up displays (HUDs) for 3D display. However, conventional coarse integral imaging and coarse integral volumetric imaging systems face challenges related to visible seams in the lens array and the emergence of moiré patterns caused by layered liquid crystal panels (LCDs), that significantly degrade image quality. This paper presents a solution to these problems by employing an integrated interleaved Fresnel lens sheet to achieve seamless 3D images with smooth motion parallax while using layered transmissive panels to generate volumetric images free from moiré.

83‐2: Invited Paper: High‐Performance Liquid Crystal Grating for Holographic 3D Display Application

Fast‐switching high‐efficiency liquid crystal grating is a key component in holographic true‐3D display systems. In this paper, we present our research and development of a 10.7” liquid crystal grating with 2‐3 millisecond switching time, close‐to‐ideal deflection efficiency, and >100 polarization contrast. The high performance is achieved by optimizing the design and process of the liquid crystal grating panel as well as the optical module stack. Several key design principles are analyzed and verified. Based on the developed liquid crystal grating, a 10.4” full‐color naked‐eye holographic 3D display prototype is successfully realized.

Reference-free in situ rapid regional calibration of phase-only spatial light modulators.

Spatial light modulators (SLMs) have become an indispensable element in modern optics for their versatile performance in many applications. Among various types of SLMs, such as digital micromirror devices (DMD), liquid crystal-based phase-only spatial light modulators (LC-SLMs), and deformable mirrors (DM), LC-SLMs are often the method of choice due to their high efficiency, precise phase modulation, and abundant number of effective pixels. In general, for research grade applications, an additional SLM calibration step is required due to fabrication imperfection resulting in non-flat liquid crystal panels and varying phase responses over the SLM area. Here, we demonstrate a straightforward approach for reference-free orthogonal calibration of an arbitrary number of SLM subregions which only requires the same measurement time as global calibration. The proposed method requires minimal optical elements and can be applied to any optical setup as is. As a benchmark performance test, we achieved a 2.2-fold enhancement in correction efficiency for wavefront shaping through scattering media utilizing the calibrated 2160 subregions of the SLM, in comparison with a single global look-up table (LUT).

Complex RGB spatial light modulation with a dual-layer in-plane switching liquid crystal panel

Complex RGB spatial light modulators are required to produce full-color holographic displays. In particular, complex spatial light modulation, which modulates the amplitude and phase of incident light is essential for noiseless dynamic computer-generated hologram synthesis. The feasibility of full-color holographic image generation through the dual-layer in-plane switching liquid crystal plane is theoretically validated and experimentally demonstrated.

Innovative stacked liquid crystal panel for automotive display: driver-oriented privacy and passenger accessibility.

We propose a switchable privacy display with liquid crystals for co-driver displays (CDDs) in vehicles. The display minimizes driver distraction while allowing the co-driver to enjoy infotainment content. By combining electrically controllable birefringence (ECB) and hybrid-aligned nematic (HAN) cells, we control the viewing angle of the display. Our device achieves an operating angle of 30°, effectively blocking the driver's view while providing a wide viewing angle for the co-driver. It maintains excellent transmittance properties in privacy and public modes, with symmetric luminance characteristics. The versatility of the proposed display extends to various technologies like LCDs, OLEDs, and micro-LEDs. This switchable privacy display has the potential to enhance driver safety and infotainment experiences in vehicles.

Dual‐view integral imaging display with adjustable optimal viewing distance

AbstractWe propose a dual‐view integral imaging display that provides two three‐dimensional scenes at the same time. An adjustable pinhole array is generated by using a liquid crystal panel. The horizontal pitch of pinhole is adjustable, while the vertical one is unadjustable. The center of each elemental image is deviation from that of the corresponding pinhole. The light rays emitted from two kinds of elemental images are propagated into the left and right viewing directions. The horizontal viewing ranges are unrelated to the horizontal pitch of pinhole and the optimal viewing distance. By changing the horizontal pitch of pinhole, the optimal viewing distance is easily adjusted without loss of viewing angle. We developed an experimental apparatus and verified the proposed hypothesis.

Integral imaging three-dimensional display system with anisotropic backlight for the elimination of voxel aliasing and separation.

Compared with conventional scattered backlight systems, integral imaging (InIm) display system with collimated backlight can reduce the voxel size, but apparent voxel separation and severe graininess still exist in reconstructed 3D images. In this paper, an InIm 3D display system with anisotropic backlight control of sub-pixels was proposed to resolve both voxel aliasing and voxel separation simultaneously. It consists of an anisotropic backlight unit (ABU), a transmissive liquid crystal panel (LCP), and a lens array. The ABU with specific horizontal and vertical divergence angles was proposed and designed. Within the depth of field, the light rays emitted from sub-pixels are controlled precisely by the ABU to minimize the voxel size as well as stitch adjacent voxels seamlessly, thus improving the 3D image quality effectively. In the experiment, the prototype of our proposed ABU-type InIm system was developed, and the spatial frequency was nearly two times of conventional scattered backlight InIm system. Additionally, the proposed system eliminated the voxel separation which usually occurs in collimated backlight InIm system. As a result, voxels reconstructed by our proposed system were stitched in space without aliasing and separation, thereby greatly enhancing the 3D resolution and image quality.

High-Aperture-Ratio Dual-View Integral Imaging Display.

Low aperture ratio is a problem in the conventional dual-view integral imaging (DVII) display using a point light source array. A high-aperture-ratio DVII display using a gradient width point light source array is reported in this work. The elemental Images 1 and 2, which are alternatively aligned on a liquid crystal panel, are illuminated by the light rays emitted from an assigned point light source. The optical path is optimized by optimizing the widths of the point light sources. The aperture ratio of the proposed DVII display was demonstrated as 1.88 times the conventional DVII display. Experiments showed that the vertical viewing range is related to the vertical width of the first row point light source, whereas the aperture ratio is related to the vertical widths of all point light sources. By optimizing the widths of the point light sources, the aperture ratio is enhanced without loss of viewing range.

Programmable plenoptic function for high-quality directional backlight autostereoscopy

A directional backlight autostereoscopy is characterized with well-collimated illumination directionality but generating a homogeneous distribution over the entire display screen over large viewing volume presents significant technical challenge. By taking advantage of the freedom to optimize the backlight, imaging optics and display panel, the adoption of plenoptic function is proposed and applied to the directionally illuminated autostereoscopy to provide viewers to perceive high-quality glass-free three-dimensional display at various viewing locations. With the programmable light-emitting diode arrays and liquid crystal display panel in conjunction with composite Fresnel lens array, an ideal autostereoscopic display is demonstrated. Assisted by retina-tracking and plenoptic function harnessing, high-quality autostereoscopy can be perceived within a large viewing volume with a conventional directional backlight autostereoscopic system but without using extra hardware component.

11‐1: 100‐Microsecond Response In‐Plane‐Only Retardation Switching by Applied Voltage Polarity‐Dependent Smectic Liquid Crystals

Opposite direction short pulse insertion to an SSD (Smectic Single Domain) liquid crystal panel has revealed significant shortening of decay time from 250 ms with a simple pulse to 50 ms with the short pulse at 8 V, 1 ms main pulse duration preserving its in‐plane only retardation switching property.

Complex spatial light modulation capability of a dual layer in-plane switching liquid crystal panel

Complex spatial light modulator (SLM), which can simultaneously control the amplitude and phase of light waves, is a key technology for wide-range of wave-optic technologies including holographic three-dimensional displays. This paper presents a flat panel complex spatial light modulator that consists of dual in-plane switching liquid crystal panels with double-degrees of freedom of voltage inputs. The proposed architecture features single-pixel level complex light modulation enabling complex light modulation in entire free space, which is most contrast to conventional macro-pixel based complex modulation techniques. Its complex light modulation capability is verified with theoretical simulation and experimental characterization, and a three-dimensional holographic image reconstruction without conjugate noise. It is believed that the proposed flat panel complex SLM can be an essential device for a wide range of advanced wave optic technologies.

Selective detection of microcracks under the surface of glass substrates by non-contact stress-induced light-scattering method with temperature variations

Demand for flexible electronics is increasing due to recent global movements related to IoT. In particular, the ultra-thin glass substrate can be bent, its use is expanding for various applications such as thin liquid crystal panels. On the other hand, fine-polishing techniques such as chemical mechanical polishing treatments, are important techniques in glass substrate manufacturing. However, these techniques may cause microcracks under the surface of glass substrates because they use mechanical friction. We propose a novel non-contact thermal stress-induced light-scattering method (N-SILSM) using a heating device for inspecting surfaces to detect polishing-induced microcracks. In this report, we carry out the selective detection of microcracks and tiny particles using an N-SILSM with temperature variation. Our results show that microcracks and tiny particles can be distinguished and measured by an N-SILSM utilizing temperature change, and that microcrack size can be estimated based on the change in light-scattering intensity.

Development of a Fringe Printer With 0.35 μm Pixel Pitch

The development of computational devices can provide computer-generated holograms (CGH) of over 100 Giga-pixel easily. The performance improvement of the graphical processing unit makes calculations faster with a normal personal computer. In contrast, the output device of CGH is not reported much. Since CGH is a fringe pattern, high resolution and fine pixel pitch are required for the output device. We have been developing a direct fringe printer, which consists of a laser, an X-Y stage, an SLM, and optical parts available on the market. Our previous report presented a liquid crystal panel, which was used for SLM that had full HD resolution and 7 μm pixel pitch. Since the Pixel pitch of the liquid crystal panel is not small enough for CGH, the optical setup works to demagnify the pixel pitch of the printed fringe pattern. To record high resolution CGH, the calculated fringe pattern is split and exposed in tiles by the X–Y stage. The results showed a 0.44 μm pixel pitch and over 100 Gpixel CGHs. However, to output more high-quality CGH, the development of pixel pitch and resolution is very important. In this paper, we review the optical system of a fringe printer that achieved an output of 0.35 μm pixel pitch CGH. We also investigate the performance of the new fringe printer.

Research on fracture behaviour of the adhesive sealant based on energy failure criterion for TFT-LCD

The adhesive sealant is a crucial structure connecting color filters and thin film transistors in liquid crystal panels. Research on the fracture progress of the connection structure is heavily needed in reliability evaluation engineering. In this work, three types of adhesive sealants with different widths were tested by the uniaxial tensile experiment to obtain their fracture process curves, which conformed to the brittle fracture characteristics described by the bilinear cohesion zone model. Then, according to the theory of engineering fracture mechanics, the Dugdale-Barenblatt plastic zone model was employed to analyze the adhesive sealant with hole defects, and it was simplified to mode ? fracture mechanics problem. Calculating with finite element numerical simulation, the numerical relationship between the stress field of the internal defect and the external stress of the material was obtained, and the brittle fracture behavior model was deduced as related to the defect size. Applying the model to the adhesive sealant, the average error of the model value after the correction was reduced from 7.98-12.13% to 6.84-7.53%, and the overall error was only within 15%. The model includes the material’s basic characteristics and the defect’s size that affect the fracture process, provides a theoretical basis for predicting the fracture of the sealant and improving the strength of bonded joints, thus is of great significance for material application and fracture analysis in engineering.

Integral imaging 3D display based on dual time multiplexing with liquid crystal aperture array

AbstractDue to the limitations of the lens array of the integral imaging display, the viewing angle and resolution are mutually restricted in space, and are difficult to improve at the same time. We propose an integral imaging system based on dual time division multiplexing using a liquid crystal aperture array to improve viewing angle and resolution simultaneously. A liquid crystal panel is introduced into the traditional integral imaging display system as an adjustable aperture array, which is used to change the imaging effect of the micro‐lens array and to realize the dual time division multiplexing of elemental image pixels. The liquid crystal aperture array is controlled to gate different lenses and different positions on the lens at different times, then the corresponding elemental image array is rendered. Thus, the spatial constraints of viewing angle and resolution are transformed into the time domains by multiplexing. Based on the proposed scheme, this paper also proposes a synchronous rendering algorithm for elemental image array and aperture array patterns in the different multiplexing periods. To verify the feasibility of the scheme, we built a prototype display and the experimental results verified that our method achieved certain improvements in viewing angle and resolution.

P‐5.12: Research on Driving Method of Oxide TFT Liquid Crystal Panel Based on TED Scheme

A 13.3“ FHD 60Hz Oxide TFT‐LCD with MUX3 hove been developed using TED Scheme. Since the high mobility of oxide TFT,2 MUX schemes and 3 MUX driving method has been analyzed in TED Scheme. Display performance and Cost and Power consumption benefit from new MUX Driving Method with compensation. Due to material saving design in ted, the assembly material can be changed from PCB to only FPC. And the Screen‐to‐Body Ratio of Notebook can achieve from 70% up to 92% with TED IC by MUX3 design.

39‐1: Invited Paper: Advanced Hyper‐Viewing Angle Controllable LCD

We have developed a new viewing angle controllable liquid crystal panel we called it lens type switching cell, which can effectively control the light through a special electrode design and rubbing conditions. In the structure, the design of the switching cell combined with the based panel and the backlight is called Advanced Hyper‐Viewing Angle Controllable (AH‐VAC) LCD. This panel In addition to having a good anti‐peep effect, the sharing mode can also have a good light viewing angle characteristic according to the voltage setting.

Integral 3D/2D partially convertible display using geometric phase lens array

Conversion between three-dimensional (3D) and high-definition two-dimensional (2D) images is required to reproduce various video content. Conventional 3D/2D conversion methods based on integral 3D displays mainly aim to convert between 3D and 2D images on the entire display screen. Here, we propose a display method for partial conversion between 3D and 2D images using a geometric phase lens (GPL) array for the backlight control of a liquid crystal (LC) panel. In our method, the backlight is switched between a point light source (PLS) array and diffused light using a GPL array, diffusion plate, and polarization switching element. Integral 3D and high-definition 2D images are simultaneously reproduced on the same screen by displaying elemental images and 2D images on the LC panel according to the state of the backlight. Through numerical simulation experiments, we analyzed the resolution characteristics of 3D images and obtained the design policy of the PLS size and pixel size of the LC panel. Based on the analysis results, we prototyped a display system using a monochromatic LC panel with 8K resolution and evaluated the quality of backlight switching and resolution characteristics of 3D images. Further, we confirmed that 3D images with approximately 16,000 pixels and 2D images with 8K resolution are partially convertible.

P‐11.4: Development of PI‐less IPS/FFS Liquid Crystal Panel with Reactive Self‐Aligning Additive

In this work we demonstrate the development of the FFS‐mode self‐alignment LCD based on UV‐reactive additive and LC media. We have already successfully developed a prototype of 6.0 inch FFS LCD panel by using the self‐alignment technology. The self‐alignment LCD panel shows a considerable properties, such as high brightness and contrast ratio. The optic‐electrical characteristics are discussed in this report.

P‐5.3: Research on Driving Method of Oxide TFT Liquid Crystal Panel Based on TED Scheme

A 13.3“FHD 60Hz Oxide TFT‐LCD with MUX3 have been developed using TED Scheme. Since the high mobility of oxide TFT,2 MUX schemes and 3 MUX driving method has been analyzed in TED Scheme. Display performance and Cost and Power consumption benefit from new MUX Driving Method with compensation. Due to material saving design in ted, the assembly material can be changed from PCB to only FPC. And the Screen‐to‐Body Ratio of Notebook can achieve from 70% up to 92% with TED IC by MUX3 design.