Hyungki Hong

Reduction of spatially non-uniform 3D crosstalk for stereoscopic display using shutter glasses

Abstract In 3D technology, when the image isolation between the left image and right image is incomplete, each eye can see not only wanted image but also unwanted image as well. And for some types of 3D technology, this leakage of the unwanted image is not spatially uniform. In making this leakage less noticeable by the modification of the 3D image data, one value of the modification condition can make the leakage smaller at one position but larger at other positions of the 3D display due to this non-uniformity. When the modification conditions dependent on the display positions are determined and applied to the image data, the leakage is observed to reduce at all the positions of the 3D display.

Angular dependence of the performance of stereoscopic liquid‐crystal‐display (LCD) television using shutter glasses (SG)

— 3-D cross-talk typically represents the ratio of image overlap between the left and right views. For stereoscopic LCDs using shutter-glasses technology, 3-D cross-talk for stereoscopic LCD TV with a diagonal size of 46 in. and vertical alignment (VA) mode was measured to change from 1% to 10% when the stereoscopic display is rotated around the vertical axis. Input signals consist of the left and right images that include patterns of different amounts of binocular disparity and various gray levels. Ghost-like artifacts are observed. Furthermore, intensities of these artifacts are observed to change as the stereoscopic display is rotated about the vertical axis. The temporal luminance of the LCD used in stereoscopic TV was found to be dependent on the viewing direction and can be considered as one cause of the phenomenon of angular dependence of performance for stereoscopic displays.

Analysis of the performance of the electric-field-driven liquid crystal lens (ELC Lens) for light of various incident angles

The electric-field-driven liquid crystal lens (ELC) induces the lens effect by the spatially non-uniform distribution of the refractive index. A scheme to analyse the performance of the ELC lens for the lights of various incident angles is devised by the calculation of the phase through the ELC lens and the determination of light ray directions from these phases. The calculated results show that the ELC lens changes the incident light of the plane wave into a focused wave and the focal distance becomes shorter for larger incident angles.

Analysis of polarisation change in an electric field-driven liquid crystal lens of cylindrical type where LC are aligned twisted

Electric field-driven liquid crystals (ELC) use the non-uniform distribution of LC directors and show strong dependence on the polarisation direction of the incident light. Phase changes by an ELC lens where LC directors are twisted are investigated. When the polarisation direction of incident light is parallel to the rubbing of the LC cell of the ELC lens on the side of the incident light, the polarisation direction of the propagating light follows the twist of the LC directors. Hence, outgoing light is still linearly polarised and its phase profile can be controlled to match that of a geometric cylindrical lens.

Simple method of characterizing the spatial luminance distribution at the user position for autostereoscopic 3‐D display

— The image quality of autostereoscopic 3-D displays strongly depends on the user position. So, characterization of the spatial luminance distribution at the user position is important. For the measurement of the spatial luminance distribution, a method that places a diffuser screen at the user position and is illuminated by a 3-D display has been investigated. By placing the diffuser screen and 3-D display non-parallel, the luminance distribution at the various distances can be determined. Though the accuracy of this measurement method is somewhat limited, the measuring procedure is fast and simple, compared with other time-consuming methods.

Change of the observed binocular disparity of the moving 3D object in 3D technology based on the time-division

Abstract In 3D technology based on the time-division, the time difference exists between the observed images of the left and the right eye. When the moving 3D image is displayed, this time difference can cause the change of the observed binocular disparity and the perceived depth, compared with those of the static 3D images. The amount of the disparity change is investigated in consideration of 3D display and 3D capturing device. Detailed effect and methods of preventing this change are described.

Motion artifacts observed in 3-D LCDs that use shutter glasses (SG 3D)

— Motion artifacts observed in 3-D LCDs using shutter glasses (SG 3D) has been investigated. A ghost-like artifact has been observed for static images due to incomplete image separation between the left and right views. The observed motion artifacts are different for the left and right views. And they occur even for images with zero binocular disparity. In this respect, the phenomena of observed artifacts in 3-D moving images are differentfrom those of 3-D static images. 3-D motion artifacts were analyzed and are related to the moving speed of the images and the amount of binocular disparity.

Analysis of focal length of blue-phase liquid crystal (BPLC) cylindrical lens for the light of the various incident angles and polarisations

Horizontally non-uniform electric field along the vertical direction inside blue-phase liquid crystal (BPLC) layer induces the Gradient index (GRIN) lens effect. Dependence of lens performance on the incident angle and polarisation is investigated by calculating the spatial phase distribution and the direction of wave front for lights passing through the BPLC layer. The calculated trajectories of light rays show that the focal distance for e-wave is less affected by the incidence angle than the focal distance of the o-wave. This can be attributed to the fact that steepness of spatial distribution of the effective refractive index for e-wave decreases for the larger incident angles.

Analysis of the generation of multi-domain in vertical alignment (VA) mode caused by the fringe field on the side of the lower substrate

The generation of multi-domain vertical alignment (VA) is important in order to reduce the dependence of electro-optical characteristics on viewing angle characteristics. Fringe fields of different intensities are generated by the control electrode and slit pattern of the pixel electrode on the side of the lower substrate. These fringe fields are used to generate the multi-domain inside the liquid crystal cell. As the voltage of the control electrode is fixed and AC voltage is applied to the pixel electrode, domains of different configurations are induced depending on the (+) or (-) sign of the first frame. Once domains are generated, these remain unchanged for much longer than the duration time of one frame, even at the pixel voltage of the opposite sign.

Polarisation rotator consisting of two layers of twisted nematic LC, which shows little dependence on the initial polarisation direction and the wavelength

ABSTRACT Performances of typical HWP (half-wave plate) or the one layer of the twisted nematic LC as the polarisation rotator are affected by the wavelength of the incident light and the initial polarisation direction of the incident linear polarisation. A new configuration that two layers of the twisted LC were aligned with the angular difference of 90°, was considered. Theoretical analysis by Jones matrix was used to derive the change of the polarisation state at the proposed configuration and to investigate the dependence on the wavelength and the initial polarisation direction. Commercial LC simulator was used to quantitatively investigate the effectiveness of the proposed configuration. Theoretical analysis and the calculated results show that the performance of the proposed configuration was less dependent on wavelength as compared with the one layer of twisted nematic LC. GRAPHICAL ABSTRACT