Invisible materials have attracted attention for anti-counterfeiting and traceability. We have focused on antimony-doped tin oxide (ATO), which can be used for the anti-counterfeiting and traceability applications. By controlling the amount of antimony doping, we have succeeded to prepare antimony tin oxide (ATO) inks with high transparency under visible light and high absorption under near-infrared light. In addition, by interpolating the color difference between the image to be given invisible information and the ATO ink, we have succeeded in imparting information on paper that is difficult to see in the visible region but readable in the near-infrared region.

The use of digital devices, especially for school learning, is growing rapidly. Although the use of digital devices has positive effects, their prolonged use can lead to visual fatigue, myopia, and physical fatigue. To address these concerns, we developed functions to measure viewing distance and posture by capturing the user's face and body position using the front camera of their digital devices. Furthermore, we derived an approximation equation to determine the viewing distance based on the interpupillary distance of the captured image and examined its validity. To measure posture, we proposed a method to determine whether the observer is leaning forward or upright. Using the developed functions, the simultaneous time-series measurement data of viewing distance and postural change were graphically presented, demonstrating that it is possible to presume the observer's condition and provide appropriate health support. Moreover, the application of the proposed measurement method in school learning was discussed.

We propose an adjustable-focus lens composed of a liquid crystal and a Fresnel lens fabricated from a liquid-crystalline polymer. Using vertically aligned liquid-crystalline polymers and fabricating Fresnel lenses by the imprinting method, we achieved uniform, vertically aligned liquid crystals on a Fresnel lens. The results demonstrate that a high-quality, adjustable-focus liquid-crystal lens that does not exhibit light scattering caused by the surface structure of the Fresnel lens can be realized.

We are focusing our research attention on the improvement of performance for the intelligent reflecting surfaces (IRS) using liquid crystals. By realizing characterization of dielectric properties in liquid crystals using coaxial line in a wide range of frequency dispersion from 1 to 50 GHz, it is revealed that the 3-ring or 4-ring compounds possessing a high nematic-isotropic transition temperature exhibit the effects of reduction for loss tangent. For improving response time and loss tangent of IRS antenna using liquid crystals, low loss tangent reaching closely to 0.01 at frequency over 40 GHz band and shortening decay time for the response in almost half were achieved simultaneously by introducing para-terphenyl liquid crystal compounds without polar groups.

In this paper, we have proposed an alingment-controlling sandwiched spacer that controls the alignment of liquid crystals (LC) in fixed-curvature LC displays without using an alignment film and serves as a spacer between rigid curved substrates. This spacer is flexible and does not require additional LC alignment film. The spacer was fabricated by a transfer method using polysiloxane resin. As a result, we fabricated curved LC devices using alignment-controlling spacer and curved glass, and this device can move LC alignment. It was found that the polysiloxane surface causes the liquid crystal molecules to be oriented perpendicularly to the polymer side surface. This device lead to durable curved LC displays without solid stick spacers that break easily.

This study proposed a two-direction electric field driving method for thick-film liquid crystal devices aimed at the millimeter-wave phase modulation of reflected arrays. The findings illustrate that a meticulous electrode shape design and strategic exploitation of the elastic orientation behavior yield both heightened liquid crystal molecule responsiveness and augmented phase modulation capabilities.

Gravure offset printing succeeded in forming bumps with a minimum diameter of 6 µm within 5% errors. We attempted to derive the design formulas for the intaglio cell shape in order to accurately print to the specified bump diameter. As a result of experiments, it is found that tapering the cell openings increased the amount of paste released from the intaglio. If the bore diameter of the cell was less than 10 µm, the printed bumps diameter depended on the aperture diameter, about our developed solder paste. We generalized what we reported at IDW ’23 and derived the design formulas that are applied to any paste or printing conditions. We applied the design formulas to a specific example and verified them usefulness.

Motion field coding is an essential technique for exploiting temporal correlations in the ongoing standard of Video-based Dynamic Mesh Coding (V-DMC), which is crucial for efficient dynamic mesh compression. In V-DMC, the motion field comprises a set of motion vectors (MVs) that represent the positional changes of vertices between corresponding decimated meshes (called base meshes in V-DMC) of current and reference frames. This paper presents an enhanced motion field coding approach that effectively reduces the number of MVs required. The proposed method leverages the observation that base meshes often contain duplicate vertices with identical MVs. By integrating these vertices, the method achieves a more compact representation, while distinct MVs for the few duplicate vertices are explicitly coded to preserve mesh quality. Experimental results using MPEG test sequences demonstrate that the proposed approach can decrease the MV data size by up to 20% without compromising the quality of the reconstructed meshes.