Electrophotography (EP) has been used for decades to print quickly, cheaply, and reliably in offices and homes around the world. It has been shown that the use of EP to print three-dimensional (3D) structures is feasible. In fact, multiple-layered prints are already commercially available in the form of color prints, but that is a limited number of layers. If the number of layers could be increased to produce functional 3D-printed structures, the desirable attributes of EP include: speed, reliability, selective coloring, ability to print a thermoplastic, multi-material printing, and the ability to print materials directly without the need for a transport medium, such as liquid ink formulations. Preliminary tests have confirmed the feasibility of using EP as an additive manufacturing (AM) technology. However, similar issues were encountered to those previously reported in the literature, namely the non-uniform brittle 3D structures that resulted as the number of layers increased. In order to determine the factors that affect the formation of these defects, an experiment was developed to identify these factors. Four independent factors were selected based on preliminary observations: the base substrate, the number of materials (i.e., colors), percentage fill (i.e., halftoning), and the use of graded transitions. A full factorial experiment was designed which resulted in 24 experimental conditions. The samples that were generated were measured at different layer intervals, 10, 20, and 30 for surface roughness, sample weight, height, curl, and surface quality as indicators of the progress. The results indicate that the base substrate plays an important role for how the sample curls but not for the smoothness of the surface; it also confirms that the more material is placed on the sample, the rougher the sample surface becomes. An interesting observation is that the leading edge of the sample into the fuser rollers was always rougher than the trailing edge.

A single-layer organic photoreceptor for electrophotography with relatively low concentrations of phthalocyanine pigments dispersed in a suitable insulating binder polymer, which exhibits the induction effect, is generally referred to as a high-gamma photoreceptor. Surface charges from corona ions can be injected into the photoconductive layer through chemicals adsorbed on the free surface generated by corona discharge. It has been confirmed experimentally and theoretically that an overcoat layer is effective in protecting the surface of the high-gamma photoreceptor from surface-charge injection. In this study, a high-gamma photoreceptor with X-type metal-free phthalocyanine pigment dispersed in polyester binder polymer is overcoated with isocyanate. The theoretical model, which takes into account the distributed structural-trap depth, demonstrates well the photoreceptor’s photoinduced-discharge and dark-discharge characteristics.

A reflection-type paper-like display based on electrically induced particle movement is proposed. The principle of the display is based on both black and white toner particles moved by applying voltage. Due to its excellent display characteristics, such as high contrast of black and white images and long image memory time, it is expected that the proposed display (called a “toner display”) will find use as electronic paper. The operation principle of the toner display is based on electrically induced movement of charged toner particles. Two types of charged particles (black and white) with opposite polarity are enclosed in the air space between two transparent electrodes. Black toner particles are attracted to the top electrode by electrostatic force across an insulating layer, to display a solid black image. The black toner particles can be transferred to the counter electrode by reversing the polarity of the electric field to display a solid white image. Experiments were carried out to examine the dependence of the display characteristics on the gap between electrodes and the mixing weight ratio of black and white particles. The display contrast and driving voltage were determined by the electrical charge of particles in the display cell. In this study, the triboelectric charges of particles in the display cell were measured using a charge-to-mass (Q/M) meter. These charges were determined to be dependent on the mixing ratio of the two types of particles. The triboelectric charging mechanism between small toner particles is also discussed.

In this article, principal component analysis is applied to pigmentation distribution in the whole face to obtain feature values, and the relationship between the obtained feature vectors and age is estimated by multiple regression analysis to simulate the changes of facial images in women of ages 10 to 80. Since the human face receives more attention than other body parts, a change of a small quantity of the features in a face makes a large difference to its appearance. We can divide the features into two categories. One category is physical features such as skin condition and shape, and the other is physiological features, which are influenced by age and health. In the beauty industry, the synthesis of skin texture is based on these two kinds of feature values. Previous works have analyzed only small areas of skin texture. By morphing the shapes of facial images to that of an average face and extending the analyzed area to the whole face, the authors’ method can analyze pigmentation distributions in the whole face and simulate the appearance of a face as a function of changing the person’s age.

In this article, an amorphous selenium (a-Se) flat-panel detector based on a high-gain, compact active pixel sensor (APS) architecture is proposed for digital radiography. The individual in-pixel APS circuits on the array consist of two thin-film transistors with read, reset, and DC bias signals supplied by two adjacent gate (row) lines by sequential row scanning. High-gain (>10), low dark current (∼1 fA), and 90% pixel area can be achieved for the x-ray detector at a 50 μm pixel pitch. A digital readout system is integrated with the 160 × 160 APS panel with 14-bit grayscale resolution and 160 μs integration time per scanning channel for x-ray image readout. The a-Se x-ray photoconductor is characterized by material structure and photocurrent response under x-ray irradiation. The fully integrated detector is demonstrated using x-ray phantom images.

A method is proposed for estimation of the wide-area color signals of the surrounding scene in the image reflected on the corneal surface. A digital color camera and the human eyeball are used to develop a simple imaging system without the need for any specialized devices. First, the authors introduce the corneal imaging system. Second, they correct the geometric distortion of the reflected image using gnomonic projection. Third, the color signals in the surrounding scene are estimated from the RGB image data according to the Wiener estimator. The corneal image consists of a combination of specular and diffuse reflections from the cornea and the iris. The desired color signals are recovered only from the specular reflection component after removing the diffuse reflection component. Finally, experiments are performed in several different conditions. The results demonstrate that the proposed corneal imaging method can estimate reliable color signals over a wide area.