A continuous‐viewing‐angle‐controllable liquid‐crystal display using a blue‐phase liquid crystal

Abstract— A continuous‐viewing‐angle‐controllable liquid‐crystal display (LCD) using a blue‐phase liquid crystal is proposed. To realize both wide‐viewing‐angle (WVA) mode and narrow‐viewing‐angle (NVA) mode with a single liquid‐crystal panel, each pixel is divided into a main pixel and a subpixel. The main pixel is for displaying images in both modes. The subpixel is for displaying images in WVA mode and controlling the viewing angle in NVA mode. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.     

Resolution enhancement of integral‐imaging three‐dimensional display using directional elemental image projection

Abstract— A new approach to resolution enhancement of an integral‐imaging (II) three‐dimensional display using multi‐directional elemental images is proposed. The proposed method uses a special lens made up of nine pieces of a single Fresnel lens which are collected from different parts of the same lens. This composite lens is placed in front of the lens array such that it generates nine sets of directional elemental images to the lens array. These elemental images are overlapped on the lens array and produce nine point light sources per each elemental lens at different positions in the focal plane of the lens array. Nine sets of elemental images are projected by a high‐speed digital micromirror device and are tilted by a two‐dimensional scanning mirror system, maintaining the time‐multiplexing sequence for nine pieces of the composite lens. In this method, the concentration of the point light sources in the focal plane of the lens array is nine‐times higher, i.e., the distance between two adjacent point light sources is three times smaller than that for a conventional II display; hence, the resolution of three‐dimensional image is enhanced.     

An integral‐imaging‐based head‐mounted light field display using a tunable lens and aperture array

A head‐mounted light field display based on integral imaging is considered as one of the promising methods that can render correct or nearly correct focus cues and address the well‐known vergence‐accommodation conflict problem in head‐mounted displays. Despite its great potential, it still suffers some of the same limitations of conventional integral imaging‐based displays such as low spatial resolution and crosstalk. In this paper, we present a prototype design using tunable lens and aperture array to render 3D scenes over a large depth range while maintaining high image quality and minimizing crosstalk. Experimental results verify and show that the proposed design could significantly improve the viewing experience.     

Depth‐enhanced integral‐imaging 3D display using different optical path lengths by polarization devices or mirror barrier array

Abstract— Depth‐enhanced integral three‐dimensional (3D) imaging using different optical path lengths by using a polarization selective mirror pair or mirror barrier array is proposed. In the proposed approach, the enhancement of image depth is achieved by repositioning two types of elemental image planes, thus effectively two central depth planes are obtained. One of the two implementation methods makes use of the two‐arm structure that has different optical path lengths and polarization‐selective mirrors. The other utilizes the mirror barrier array. The primary advantage of the method with polarization devices is that we can observe 3D images that maintain some level of viewing resolution with a large depth difference without any mechanical moving part. The mirror barrier array has the advantage of the compact thickness. We demonstrated and verified our proposals experimentally.     

Practical implementation of a depth‐feeling‐enhanced two‐plane electro‐floating display system using three‐dimensional integral images

Abstract— Although there are numerous types of floating‐image display systems which can project three‐dimensional (3‐D) images into real space through a convex lens or a concave mirror, most of them provide only one image plane in space to the observer; therefore, they lack an in‐depth feeling. In order to enhance a real 3‐D feeling of floating images, a multi‐plane floating display is required. In this paper, a novel two‐plane electro‐floating display system using 3‐D integral images is proposed. One plane for the object image is provided by an electro‐floating display system, and the other plane for the background image is provided with the 3‐D integral imaging system. Consequently, the proposed two‐plane electro‐floating display system, having a 3‐D background, can provide floated images in front of background integral images resulting in a different perspective to the observer. To show the usefulness of the proposed system, experiments were carried out and their results are presented. In addition, the prototype was practically implemented and successfully tested.     

Integral floating‐image display using two lenses with reduced distortion and enhanced depth

Abstract— An integral floating display (IFD) with a long depth range without floating lens distortion is proposed. Two lenses were used to reduce barrel distortion of the floating lens and three‐dimensional (3‐D) image deformation from object‐dependent longitudinal and lateral magnifications in the floating‐display system, combined with an integral imaging display. The distance between the floating lenses is the sum of their focal lengths. In the proposed configuration, lateral and longitudinal magnifications are constant regardless of the distance of the integrated 3‐D images, so the distortions from the distant‐dependent magnifications of the floating lens do not occur with the proposed method. In addition, the proposed floating system expands the depth range of the integral imaging display. As a result, the display can show a correct 3‐D floating image with a large depth range. Experimental results demonstrate that the proposed method successfully displays a 3‐D image without floating lens distortions across a large depth range.     

Viewing‐angle‐enhanced integral imaging system using high‐refractive‐index medium and curved micro‐lens array

In the integral imaging (II) system using a curved micro‐lens array (MLA), the viewing angle is limited by the gap mismatch. Here, we propose a system to decrease the gap mismatch for enhancing the viewing angle. In the proposed system, a layer of high‐refractive‐index medium is assembled between the display panel and the curved MLA. The principle of the proposed II system is studied in detail. Simulations based on ray tracing are performed, and the results show that the proposed II system can effectively enhance the viewing angle.     

A viewing‐angle‐controllable blue‐phase liquid‐crystal display

Abstract— A viewing‐angle‐controllable liquid‐crystal display (LCD) is proposed. When the device is only driven by an in‐plane electric field, it exhibits a wide‐viewing‐angle (WVA) mode. And it exhibits narrow‐viewing‐angle (NVA) mode when it is driven by a vertical electric field as well as an in‐plane electric field. In this manner, the viewing angle of the device can be controlled from 100° to 30°. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.     

A toroidal‐lens designed structure for static type table‐top floating image system with horizontal parallax function

A new structure of horizontal parallax table‐top floating image system with toroidal‐lens optical film was developed. In this design, the circular arranged pico‐projectors limit the angular resolution of this system and display the floating image for surrounding viewing zones. In addition, the pinhole array and toroidal‐lens layer compose the optical film in the system and correspond with each other; both of them could be considered as a repeatable unit to control the spatial resolution of image. After passing through the optical film, the direction, position, shape, and divergence angle of light field could be controlled as fan ray, which has a widely scattered angle in latitude and high directivity in longitude direction. Moreover, to confirm the optical properties, the proposed structure was built in the commercially optical software, LightTools v8.3, which is widely used in the simulation of light distribution. Based on the imaging principle and the inverse light tracking method, displaying floating image with circular viewing zones would be achieved.     

Efficiency analysis for multi‐view spatially multiplexed autostereoscopic 2‐D/3‐D displays

Abstract— The wide‐viewing freedom often requested by users of autostereoscopic displays can be delivered by spatial multiplexing of multiple views in which a sequence of images is directed into respective directions by a suitable autostereoscopic optical system. This gives rise to two important design considerations — the optical efficiency and the resolution efficiency of the device. Optical efficiency is particularly important in portable devices such as cell phones. A comparison is given between lens and barrier systems for various spatial multiplexing arrangements. Parallax‐barrier displays suffer from reduced optical efficiency as the number of views presented increases whereas throughput efficiency is independent of the number of views for lens displays. An autostereoscopic optical system is presented for the emerging class of highly efficient polarizer‐free displays. Resolution efficiency can be evaluated by investigating quantitative and subjective comparisons of resolution losses and pixel appearance in each 3‐D image. Specifically, 2.2‐in.‐diagonal 2‐D/3‐D panel performance has been assessed using Nyquist boundaries, human‐visual contrast‐sensitivity models, and autostereoscopic‐display optical output simulations. Four‐view vertical Polarization‐Activated Microlens technology with either QVGA mosaic or VGA striped pixel arrangements is a strong candidate for an optimum compromise between display brightness, viewing angle, and 3‐D pixel appearance.     

Moiré‐reduction methods for integral videography autostereoscopic display with color‐filter LCD

Abstract— Moiré‐reduction methods for integral videography displays are proposed. Integral videography is based on the principles of integral photography and extended real‐time video processing. There are two moiré‐reduction methods that can be used for integral videography displays that have a lens array and a liquid‐crystal display. The first is color moiré, and the second is intensity moiré. To reduce color moiré, an optimized color‐filter layout in the liquid‐crystal display was used. To reduce intensity moiré, a defocusing method was used. Adesign of a viewing area for the integral videography display is also presented. To control the viewing area, the lens pitch and the shape of the integral videography elemental image was changed. A 5‐in. integral videography display was implemented by using the proposed methods, and an integral videography display was evaluated.     

Full‐parallax autostereoscopic display with scalable lateral resolution using overlaid multiple projection

Abstract— A method to increase the viewing resolution of an autostereoscopic display without increasing the density of microlenses is proposed. Multiple projectors are used for the projection images to be focused and overlaid on a common plane in the air behind the microlens array. The multiple overlaid projection images yield multiple light spots inside the region of each elemental lenslet of the microlens array. This feature provides scalable high‐resolution images by increasing the number of projectors. Based on the proposed method, a prototype display that includes 15 projectors was designed and built. 3‐D images were successfully reproduced on the prototype display with full parallax and a wide viewing angle of 70°.     

Tabletop integral imaging 3D display system based on annular point light source

When the viewers sitting around the table observe 3D images, the viewing direction is generally oblique and the viewpoints should be distributed as annular. In this paper, a tabletop integral imaging (II) three-dimensional (3D) display system based on annular point light sources is demonstrated, which can present 3D images to multiple viewers in a standard annular viewing area with oblique viewing direction. The proposed system consists of annular point light sources, a Fresnel lens, a lens array, a two-dimensional (2D) display panel, and a diffuser screen. Each point light source illuminates the Fresnel lens to form parallel light and then illuminates the lens array and the display panel. A viewing sub-area is generated at the position of the diffuser screen, in which the 3D images can be viewed. Multiple viewing sub-areas are created in a way of time-division multiplexing to form a 360° annular viewing area. Compared with the previous tabletop 3D display, the viewing area can be concentrated at an oblique angle near the tabletop. The experimental results demonstrate the feasibility of the tabletop II 3D display system.     

A high‐contrast front‐projection display system optimizing the projected light‐angle range

Abstract— The problem with front‐projection displays is that the screen contrast ratio decreases under bright‐ambient conditions. To overcome this problem, the design of a special screen, composed of the diffuser whose diffusing property shows top‐hat characteristics and a sawtooth reflector, is proposed. The screen diffuses the incident image light arriving at a projection‐angle range that is a lower‐angle range than the viewing‐angle range, and reflects the ambient light out of the viewing‐angle range. In this paper, the projection‐angle range and the viewing‐angle range was optimized to improve the contrast ratio of a front‐projection display. As a result, a special screen with the above‐mentioned diffusing property was realized, and a high‐quality front‐projection display with a high contrast ratio, even in a bright room, was achieved.     

Crosstalk‐free dual‐view integral imaging display

We propose a crosstalk‐free dual‐view integral imaging display. It is composed of a display panel, a barrier array, and a micro‐lens array. The central barrier is located at the vertical central axes of the display panel and the micro‐lens array to split the element image array and the viewing zone. Moreover, other barriers are located at the margins of the elemental images and corresponding micro‐lenses to eliminate the crosstalk. The lights emitting from the left and right half of the element image array are modulated by the left and right half of the micro‐lens array to reconstruct the right and left viewing zones, respectively. A prototype of the proposed dual‐view integral imaging display is developed, and good experimental results agree well with the theory.     

Transflective blue‐phase liquid‐crystal display with corrugated electrode structure

Abstract— A transflective polymer‐stabilized blue‐phase liquid‐crystal display (BP‐LCD) with a corrugated electrode structure is proposed. To balance the optical phase retardation between the transmissive (T) and reflective (R) regions, two device structures are proposed. The first device structure has the same inclination angles but different cell gaps in the T and R regions. And the second device structure has the same cell gap but different inclination angles in the T and R regions. Both of the device structures can obtain well‐matched VT and VR curves. This display exhibits low operating voltage, high optical efficiency, and a wide viewing angle.     

A high‐resolution autostereoscopic display system with a wide viewing angle using an LCOS projector array

Abstract— This study develops an autostereoscopic display based on a multiple miniature projector array to provide a scalable solution for a high‐resolution 3‐D display with large viewing freedom. To minimize distortion and dispersion, and to maximize the modulation transfer function (MTF) of the projection image to optimize 3‐D image quality, a dedicated projection lens and an accurate six‐axis adjusting platform for the miniature projector were designed and fabricated. Image‐blending technology based on a lookup table was adopted to combine images from 30 miniature projectors into a seamless single image. The result was a 35‐in. autostereoscopic display with 60 views ata 30° viewing angle, 90° FOV, and large range of viewing distance. The proposed system exhibits very smooth motion parallax when viewers move around in front of it.     

Self‐calibration three‐dimensional light field display based on scalable multi‐LCDs

Approach to achieve self‐calibration three‐dimensional (3D) light field display is investigated in this paper. The proposed 3D light field display is constructed up on spliced multi‐LCDs, lens and diaphragm arrays, and directional diffuser. The light field imaging principle, hardware configuration, diffuser characteristic, and image reconstruction simulation are described and analyzed, respectively. Besides the light field imaging, a self‐calibration method is proposed to improve the imaging performance. An image sensor is deployed to capture calibration patterns projected onto and then reflected by the polymer dispersed liquid crystal film, which is attached to and shaped the diffuser. These calibration components are assembled with the display unit and can be switched between display mode and calibration mode. In the calibration mode, the imperfect imaging relations of optical components are captured and calibrated automatically. We demonstrate our design by implementing the prototype of proposed 3D light field display by using modified off‐the‐shelf products. The proposed approach successfully meets the requirement of real application on scalable configuration, fast calibration, large viewing angular range, and smooth motion parallax.     

Prototyping and optical evaluation of 9‐in. OCB time‐division‐multiplexing 18‐view 3‐D display

Abstract— An integral imaging time‐division‐multiplexing 18‐view 3‐D display based on the one‐dimensional integral‐imaging (1‐D‐II) technique using a 9‐in. OCB‐LCD, lenticular sheet, and active shutter has been developed. By simulating a lens shape and a shutter structure and analyzing the light‐beam profile of the increasing‐parallax‐number region to find the best conditions, depth range, and viewing angle were an enhanced and a brighter and flicker‐less 3‐D image with smooth motion parallax was obtained.     

Nonuniform viewing angle of integral imaging display

While the viewing angle (VA) is an important parameter of three‐dimensional (3‐D) displays, a method has not yet been devised to determine the VA. We proposed a new approach to determine a VA of an integral imaging display. An integrated point appears at the cross section between collected rays and a lens array; the VA of the integrated point is thus equal to the angle between the two farthest rays. This approach is useful to determine the VA of all 3‐D displays, because a 3‐D point appears in the cross section of collected rays. The result of this study showed that the VA depends on the position of the integrated point and is smaller than the VA of the conventional calculation.