Digital cameras are indispensable devices for proximal remote sensing technology and show an excellent advantage that they can cover more extensive areas by one shot than a spectral radiometer can make a measurement of a target object in a limited scope. When we make a distribution map of vegetation index estimated from the images captured by commercial digital cameras with an auto exposure function on, it is sometimes seen that the areas with anomalously high values of vegetation index appear corresponding to darkest shadow areas in visible light images. To remove the anomalous areas, we set the minimum threshold luminance of the image and found it very effective to exclude the pixels with the luminance below this threshold value from the processing of estimation of the vegetation index. It was also revealed that the minimum threshold luminance has dependence on gamma values of the image.
Thermally activated delayed fluorescence (TADF) has attracted much attention for realization of highly-efficient and low-cost organic light emitting diodes (OLEDs). OLEDs based on 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), which is one of highly-efficient TADF emitters, have been demonstrated to exhibit external quantum efficiency more than 19%. To study the decay rates from excited states of 4CzIPN, the temperature dependence of photoluminescence quantum efficiency (PLQE) has been measured in the weak photoexcitation limit in 4CzIPN-doped 1,3-bis(9-carbazolyl)benzene thin films. Characteristic features of the temperature dependence of PLQE in the weak photoexcitation limit are found, and examined by using rate equations of singlet and triplet densities.
Leuco dyes, well-known multi-functional material, can exhibit excellent thermochromic properties by combining with developer molecule which is organic compound having a hydroxyl group and long alkyl chain. Our purpose of this research is to fabricate multifunctional material enabling control of both emission and coloration by combining leuco dye-developer system with emission materials. In this study, we investigated novel thermo-responsive dual-mode displaying media showing both reflective and emissive modes in red-green-blue (RGB) three primary colors. We employed the two kinds of leuco dye derivatives into the polymeric film as thermochromic material in order to improve the switching contrast of the emissive mode. As a result, we successfully demonstrated the control of coloration and emission in RGB colors with large contrast by thermal treatments.
An aqueous resin ink was developed which can offer excellent image qualities on non-permeating media such as plastic media with an inkjet printer. The print speed with this aqueous resin ink reaches the level of solvent-inks diffused as inks for non-permeating media for sign graphic, i.e., at least 30m2/h. In order to increase the print speed, it is important that the ink has good compatibility to the coating layer of non-permeating media. It was found that kinds of solvents added to the ink were highly related to the compatibility. Furthermore, such solvents have a particular feature in common. Solvents with specific range of fractional parameter have high coating layer-solving ability. To show validity of this mechanism, a new method for evaluation of ink fixation was developed. With this new method, it was proved that higher concentration of coating-layer-solving solvent gave ink faster fixation onto the non-permeating media.
Technology for evaluating resin materials using pulse nuclear magnetic resonance (Pulse NMR), which can measure the molecular mobility, were developed. One technique was evaluating the storage stability to heat, which was developed by focusing on the high molecular mobility of the low-temperature melting component of the crystalline polyester resins for toner. Compared to the temperature modulated differential scanning calorimetry (Temperature Modulated DSC), this technique can be evaluated simply with high sensitivity. Another technique was evaluating the resin hardness, which was developed by noting that the molecular mobility of low hardness resin was high. This technique can measure the sample in any form and obtain numerical information. And it was shown to be a suitable hardness evaluation method to supplement the pencil hardness test.
Transfer performance of xerographic process is represented in the point of transfer latitude by the electric field simulation. The latitude is defined by the bias voltage window between the minimum voltage to transfer toner images and the maximum voltage to prevent defects on the image caused by discharge inside the transfer nip. In this point of view, numerical analysis on the second transfer process in an intermediate transfer system is conducted. The results of the electric field simulation indicate that the latitude can be maximized by optimizing the thickness and specific resistance of the layer inside the bias transfer roller (BTR) and that difference of dependence of maximum transfer bias voltage and minimum transfer bias voltage to the system resistance generates the transfer latitude. The procedure is useful for product design process to develop reliable product with less resources.
Toner scatter is one of the major image degradations at 2nd transfer unit in xerographic process. To clarify the mechanism of the phenomenon, one-dimensional numerical simulations on the electric field including effects of discharge were executed to investigate electric forces on toner particles. In the simulation, the electric field intensity in the process direction on a printed area was defined as a characteristic value for evaluating the degree of toner scatter. As a result, it was found that the electric field which raises the toner scatter was generated when the charge on media in a contact area is not sufficient. Factorial effects calculated by the simulation model were in good agreement with the experimental ones.
To obtain the desired images from inkjet printers, it is important to control the coalescing and wetting behaviors of the ink droplets. However, predicting these behaviors quantitatively through an experimental approach is difficult because of the speed and the minuteness of such phenomenon. Therefore, the establishment of a simulation technology to predict these behaviors is in demand. In this study, an MPS simulation method was developed based on a particle method that considered the effect of surface tension acting on the liquid-liquid and liquid-solid interfaces. Quantitative prediction of the coalescing and wetting behaviors was made possible using this technology.
A dual-mode display device which can operate in both emissive and reflective modes, having advantages of both modes, is considerable promise as a next generation display. In this review, electrochemical switching systems, which enable simultaneous control of both emission and coloration, are reviewed in order to create the novel displaying materials. A luminescent europium(III) [Eu(III)] complexes, one of the important lanthanide (III) complexes, and electrochromic molecules of viologen derivatives were combined for appearance of the multi-functionality. The Eu(III) complex emission was controlled by the electrochromism of the viologen derivatives via an intermolecular energy transfer mechanism. When viologen derivatives were in a colorless state, a strong red emission was observed from the Eu(III) complex. On the other hand, the electrochemically colored viologen derivatives effectively quenched the red emission of the Eu(III) complex. However, these systems lacked quick response and high reversibility of the fluorescence modulations. Some of the researches for improving these disadvantage of primary study are described. Furthermore, numerical representations and multi-color representations with emissive and reflective modes were also achieved.
Recently electrophotographic machines are widely used for various applications in many countries. Then Organic photoconductor (OPC) is required higher durability such as abrasion resistance and lower toner filming. One of the key materials for high durable OPC is binder resin. This is an introduction of the properties and the development of binder resin for OPC.
In the field of printing technology, toner property is progressing for the demand of saving energy, high speed printing, color printing, high quality printing. According to the toner property progress, qualities of toner binder have been changing. Concerning styrene acrylate toner binder, I explain the relationship between toner properties and toner binder properties which are consisting monomers, molecular weight distribution, glass transition point, viscoelasticity.
Fixing process in the electrographic printer requires the use of a release agent such as silicone oil to prevent the adhesion of the toner of the hot roll surface. However, this method requires an oil tank and an oil coating device, thus the device becomes complex and large. Oil-less type of image forming devices have been developed that do not use release oil in the fixing device. Instead of using release oil, a release agent like paraffin wax is added within the toner formulation. In recent years, paraffin wax has been one of the most important components of monochrome and full-color toners in the electrographic printer. Essential properties in paraffin wax for the toners are melting point, penetration, viscosity, and so on.
The toners are comprised of many materials such as binder resins, colors, charged control materials, external additives and waxes. From the surge of recent environmental awareness, energy saving is requested in the field of electrophotography. Thus, the authentication system for the energy-saving product, such as product registration to International Energy Star Program is carried out positively. In electrophotographic printing device, energy saving of the fuser, which accounts for more than 70% of electricity consumption1), is very important. The wax for toner plays an important role in this fixing process. To save energy of the fuser, it is effective to hold down the temperature of the fuser. Therefore, it is effective to use low melting point wax, which promotes the softening of the polymeric product binder resins and develops a function at low temperature. On the other hand, the toner may be exposed to temperature of around 50 degrees during preservation. If a part of the wax melts when the toner is exposed at these temperature domains, troubles such as the blocking of the toner occur. I introduce high purity ester wax indicating a low melting point and sharp fusion behavior here.
GUNZE LIMITED has commercialized the intermediate transfer belt made of polycarbonate since 1989, and has been dedicated to improve the belt on the basis of customers' needs. In order to obtain high resolution of the electrophotography, it is required in transfer process to avoid degrading the toner image formed on the OPC, transfer it successively to overlap one another on the belt, and complete the color image formed by four toner images on the belt at once, to a wide variety of printing media. G2XC belt which GUNZE developed has showed its performance of the stability of the charge and its removal, and to give high-quality images stably for long period of time. In this report, studies on the image degradations were reviewed with the fundamental technologies, and how to prevent the image degradation by using practical material technologies.
In an electrophotography system, tonner cleaning process is to wipe off a residual tonner and other adhered substances not transferred to a media such as a paper but left an image-carrier in the transfer process before next image forming cycle. Polyurethane is generally used for a cleaner blade to remove residual tonners. It is superior to other polymer for abrasion proof, has sufficient mechanical strength without adding reinforcing agent and the contamination resistant function to the image-carrier or transfer medium. This document introduces a new technology of cleaning blade to meet the trend in printing/imaging market such as high image quality, long service life and energy saving through the explanation of the blade function, the characteristic of polyurethane and its material designing.
We explain on characteristics of silicone material included metal-silicon powder for OA equipment. Thermal conductivity silicone rubbers having superior to thermal stability are released by means of dispersing metal-silicon powder formed rigid surface-layer of SiO2 into silicone polymer The material is expected improvement of fusing performance by using for fusing roller and belt.
The cycloolefin resins are amorphous transparent resins which have a good optical properties and heat resistance. Therefore they attract attentions very much because the demands of downsizing, weight reduction, high performance and cost down to optical components are recently expanding. Conventional optical resins : Polymethylmethacrylate (PMMA) and Polycarbonate (PC) are known well. But they have the polar functional groups leading to high water absorption properties and property change due to environmental change. In addition, refractive index of PMMA is low and birefringence of PC is high. The cycloolefin resins are the resins which can solve the problems of PMMA and PC by introducing the cycloolefin unit to polyolefin. APELTM is the cycloolefin copolymer (COC) developed by Mitsui Chemicals, Inc. This resin has a superior optical properties : high refractive index and low birefringence and has a superiority among same kinds of cycloolefin resins. We explain about the structure, properties and applications of APELTM.