Electrostatic Latent Image Research Articles

Method for Estimating the Charge Density Distribution on a Dielectric Surface.

High-quality color output from digital photocopiers and laser printers is in strong demand, motivating attempts to achieve fine dot reproducibility and stability. The resolution of a digital photocopier depends on the charge density distribution on the organic photoconductor surface; however, directly measuring the charge density distribution is impossible. In this study, we propose a new electron optical instrument that can rapidly measure the electrostatic latent image on an organic photoconductor surface, which is a dielectric surface, as well as a novel method to quantitatively estimate the charge density distribution on a dielectric surface by combining experimental data obtained from the apparatus via a computer simulation. In the computer simulation, an improved three-dimensional boundary charge density method (BCM) is used for electric field analysis in the vicinity of the dielectric material with a charge density distribution. This method enables us to estimate the profile and quantity of the charge density distribution on a dielectric surface with a resolution of the order of microns. Furthermore, the surface potential on the dielectric surface can be immediately calculated using the obtained charge density. This method enables the relation between the charge pattern on the organic photoconductor surface and toner particle behavior to be studied; an understanding regarding the same may lead to the development of a new generation of higher resolution photocopiers.

Potential Profile Measurement and Mechanism Analysis of an Electrostatic Latent Image by Detecting Primary Electrons

Potential Profile Measurement and Mechanism Analysis of an Electrostatic Latent Image by Detecting Primary Electrons

Formation of electrically charged microdroplets in a nonpolar solvent and assembly into patterns on charged substrates

We developed a method to form microdroplets in a nonpolar solvent and then assemble these droplets in patterns on substrates. An electrical latent image was first formed, onto which the charged droplets were assembled. This process is based on a similar principle as the xerographic process but has been applied to liquids. The electrically charged droplets were dispersed in the nonpolar solvent using electro-emulsification.We used a double-nozzle configuration and flowed the continuous phase in a smooth jet to continuously form uniform droplets. The charged droplets in a nonpolar solvent were assembled on a latent electrostatic image. The droplet charge was estimated using simulations and experiments. The simulated and experimental results were in good agreement, and the droplet charge was found to be much higher than the charges of ordinary ionized particles because the droplet electrical charge was generated by induction between the liquid interface at the nozzle and the electrode.The droplet size was controlled by changing the flow rate of the dispersed phase, and the minimum diameter was 7μm. The droplets were successfully assembled on the latent images at various latent voltages which produced varying droplet size. Charged 7- and 80-μm droplets were used to form patterns on a 500-μm-wide latent line in a nonpolar solvent using electrostatic forces. The charged droplets were also assembled on a latent image of 400μmL/S. We plan to extend the use of this method to various applications, including sensors and composite materials.

Latent Image Measurement for Dot Pattern Formed by Scanning Laser Beam

A method that enables the measurement of an electrostatic latent image equipped with a laser scanning unit is proposed. One of the features of this method is that the laser scanning unit is arranged outside the vacuum chamber. The vibration and the electromagnetic field interference of a polygon motor do not affect the orbit of the electron beam because the polygon motor is kept away from the electron optics system. A pair of laser diodes (LDs) is used as the light source of the laser scanning unit. The measurement results obtained by the proposed method provide valuable new information on latent image characteristics for exposure conditions.

Potential Profile Measurement and Mechanism Analysis of an Electrostatic Latent Image by Detecting Primary Electrons

Potential Profile Measurement and Mechanism Analysis of an Electrostatic Latent Image by Detecting Primary Electrons

Potential Profile Measurement and Mechanism Analysis of an Electrostatic Latent Image by Detecting Primary Electrons

A new method that makes possible a potential profile measurement of an electrostatic latent image is proposed. When the surface potential is greater than the acceleration voltage of the primary electron, the velocity becomes zero before the electron hits the sample. As a result, the primary electron reaches a detector without reaching the sample. The surface potential profile can be measured by detecting primary electrons while changing the applied voltage to the substrate of a photoconductor. The significant feature of this method is that the charging, exposure, and detection devices are all incorporated in the same system, making real-time measurement possible. In order to confirm the phenomenon of reciprocity law failure, the potential depth of the latent image was measured by changing the delay time when double-pulse exposure was carried out. As a result, the latent image potential tends to be formed deeper as the delay time becomes longer. The developed Electrostatic Latent Image Measuring System (ELIMS) has good performance with a measurement potential resolution of 2 V.

INCREASING OF RADIOGRAPHIC CLINICAL VALUE BY USING OF RADIO PHOTO ELECTROSTATIC IMAGING SYSTEM (XERORADIOGRAPHY)

Ordinary Radiographic film sensitive emulsion is formed by crystals which are composed by millions of ions. According to the film texture, image constructive units number that interfere the image resolution are not increased more than a certain limitation in area unite. This innovation is to present an imaging system that to compare with common similar system has precedence such as highly image resolution, image edge sharpnessenhancement, contrast improvement, patient does reduction, rapid processing and cost decrease. The Xero technique is different physical method for imaging procedures in which instead of using the photochemical function, electrostatic effect has been used. The latent electrostatic images develop through toner powder, Because the toner powder particles are fine grain as small as a few compound molecules, Consequently, in the new method, image constructive units number which are described as the toner powder particles are much many more in number than crystals of radiographic films. Xeroradiophotography system is designed and constructed based on xero physical phenomenon in which image can be formed by taking advantage of both, X-Ray and visible light complex procedure for the purpose of X-Rays quality and patients body tissue side effect reduction at the time of exposure. This system has already been made as the first archetype in the world that is possible for optimum improving soon.

Observation of Electrostatic Latent Images and Surface Potential Measurement Using Scanning Electron Microscope

Electrostatic voltmeters are generally used for potential measurements of electrostatic latent images. In this study, we are using SEM (Scanning Electron Microscope) for more detailed observation and potential measurement of electrostatic latent images; SEM can visualize electrostatic latent images as an image brightness distribution. We focused on clarification of the relation between surface potential of electrostatic latent image and brightness of SEM images. Electrostatic latent images were formed on PET (Polyethylene terephthalate) film by a corona discharger. We have observed SEM images of the electrostatic images after measuring surface potential of each latent image by using electrostatic voltmeters. We then measured distributions of brightness of the SEM images. We have successfully shown the relation between the surface potential and the brightness of SEM images. We hope SEM observation can be an alternative method for detail observations and measurements of electrostatic latent images.

The Effect of Carrier Surface Morphology on the Triboelectric and Imaging Performance of Insulative Two-Component Xerographic Developers

Xerography is based on the development of latent electrostatic images by triboelectrically-charged toner particles. In a two-component (TCD) developer, the toner particles are triboelectrically charged via energetic mixing with polymer-coated magnetic carrier beads. Since the TCD xerographic development process is non-linearly related to TCD developer properties (e.g. toner charge, toner supply, powder flow mechanics, etc.), TCD aging can be a major factor for eventual imaging failure. In this review, simple parametric models of triboelectric charging and xerographic development will be combined to illustrate some of the major effects of changes in carrier bead surface chemistry on insulative TCD xerographic development.

Dielectric Properties Study of Thin Polymer Film Layers Used in LEP

Indigo's technology is based on Liquid Electro Photography (LEP). In this process an electrostatic latent image is first produced on the Photo Imaging Plate (PIP) and then ink is transferred to PIP. Afterward the ink is transferred to the intermediate transfer media, i.e. blanket and finally to the printing media (substrate). The electro ink is transferred mainly due to electrical fields (forces). In this process different types of polymeric coatings are used on the intermediate transfer media (blanket) and the electrical ink transfer depends strongly on these polymers electrical properties. In this work we present a technique for measuring electrical properties of different types of polymeric material coatings at different conditions. This unique set-up enables working under a wide range of physical parameters: temperatures, pressures, electrical voltages and frequencies. A theoretical study of the impedance behavior and equivalent electrical circle has been developed. The analysis shows good matching between experimental and theoretical results. This technique allows better understanding of development of new polymeric materials and determining process working points, especially temperature and electrical voltages.

Potential Profile Measurement and Mechanism Analysis of Electrostatic Latent Image by Detecting Primary Electrons

A new method that makes possible a potential-profile measurement of an electrostatic latent image is proposed. The key technology is to detect a primary electron. When a surface potential is greater than acceleration voltage of the primary electron, the velocity becomes zero before the electron hits a sample. As a result, the primary electron reaches to a detector without reaching the sample. The potential distribution can be measured by detecting primary electrons while changing an applied voltage of a backside. This method is that the means of charging, exposing, and detecting are all incorporated in the same system, making real-time measurement possible.This system is being used to analyze the basis of an electrostatic latent image formed on a photoconductor. In order to confirm a phenomenon of reciprocity law failure, the latent-image depth was measured by changing the delay time when exposure was carried out a couple of times. As a result, the latent-image depth tends to be formed deep when the delay time becomes long.

Review of Toner-Based Printing Technologies and Fundamentals of Toner Charging Mechanism

Toner-based printing technologies such as electrophotography have excellent electronic printing characteristics. The toner is controlled by electrostatic force, which is determined by the product of the toner charge and the electric field acting on the toner. In electrophotography the toner is attracted to an electrostatic latent image and forms an image. Because the toner is controlled by electrostatic force, high speed printing on plain paper can be realized. Electrophotography consists of six complex processes: charging, exposure, development, transfer, fixing, and cleaning. Various technologies have been proposed to realize a simpler printing mechanism. An electrostatic printing mechanism is described in which charging and exposure occur within a single process that generates an electrostatic latent image. As examples of direct printing by this simpler mechanism, TonerJet® and toner cloud beam are reviewed. As a fundamental element of toner-based printing technology, the toner charging mechanism is summarized.

Measurement of Electrostatic Latent Image on Photoconductors by Use of Electron Beam Probe

A novel method that makes possible the measurement of an electrostatic latent image on a photoconductor is proposed. An electrostatic latent image is formed by electron charging and by laser exposing of a photoconductor within a vacuum chamber. The electrostatic latent image is measured by detecting secondary electrons generated by the scanning of an electron beam probe. When a primary electron beam hits the photoconductor, secondary electrons are generated. Secondary electrons generated in a charged area travel to an electron detector. In contrast, secondary electrons generated in an exposed area are pulled back to the photoconductor, thereby decreasing the number of secondary electrons that reach the detector. The exposed and charged areas are determined in this way. The significant feature of this method is that the means of charging, exposing, and detecting are all incorporated in the same system, making real-time measurement possible. This method has good performance with high-resolution measurement on the order of microns.

A Conceptual Model of Toner Charge Admixing

During xerographic development, charged toner particles are removed from the developer by the latent electrostatic image, and are replaced by uncharged dispensed toner particles. As a result, the total toner population in a developer contains charged incumbent particles and uncharged added particles. To maintain image quality, the latter toner particles must rapidly chargeequilibrate with the already-charged toner particles in the developer. As outlined in the present paper, a conceptual chargeadmix model based on a direct graphical analysis can provide a clear picture of toner-carrier and toner-toner charge-admixexchange processes. The model starts with the “perfect” charge admix case, and this is then used as a base for the development of a model for atypical charge admix processes. The model also describes toner charging performance from the initial developer charge-up step through the charge spectra of the final toner admix step. In this paper, predictions from the conceptual model are also reviewed for various levels of developer mixing and aging.

Momentum-Control Scavenge-less Jumping Development

A new toner-based electrographic development process is presented, which we call “Momentum-Control Scavenge-less Jumping Development” (MC-SJD). It is similar to conventional jumping development in that an AC waveform is used to drive charged toner particles across a small gap from a toned donor roll towards a photoreceptor with a latent electrostatic image. Rather than allowing toner particles to impact the photoreceptor and potentially damage any existing toned image, a four-phase waveform is used to reduce the normal component of the toner's momentum prior to its impact with the photoreceptor. The toner thus forms a nearly static cloud of charged particles near the latent image, which then gently develops onto the photoreceptor. The MC-SJD process is equally applicable to both single and dual-component development subsystems. This approach is particularly useful for image-on-image color printing architectures, but may also help improve the image quality of monochrome and conventional color prints.

Toner Printing Technology

Toner printing technologies represented by electrophotography have big advantages in electronic printing. Toner is controlled by electrostatic force and forms images on paper. So, high speed and plain paper printing are realized. The electrophotography has six processes of charging, exposure, developing, transfer, fixing, and cleaning. Charging and exposure are unified into one process to form latent electrostatic image and electrostatic printing is developed. To realize simpler printing mechanism, TonerJet® and TCB (Toner Cloud Beam) are also proposed. Electrophotography is reviewed from the fundamental viewpoint. Other toner technologies are also reviewed.

An Analysis on both Voltage Sensitivity and High Spatial Resolution with a New Electrostatic Voltmeter Having Extremely High Input Impedance

We investigated the voltage sensitivity and spatial resolution of an electrostatic voltmeter with a high input impedance of 1016 Ω or higher, which was called HZ-ESVM, applied for measuring the electrostatic latent images on a photoconductor in an electro photographic printing system. We report the simulated and experimental results of the output voltage of the HZ-ESVM as a function of probe distance (gap) from the surface of the sample under test, and experimental results of spatial resolution.In the simulated results, the simulated output ratio of the voltage between the measurement electrode the sample under test could keep the value higher than 80% at a gap of 50 μm by using a probe with the protruded length of the measurement electrode L = 100 μm. Moreover, the simulated output voltage against sample voltage achieved 95% output at a gap distance of 50 μm using a probe with a shorter length of L = 10 μm. In the experimental results, the HZ-ESVM with a probe of L = 0.32 mm and a measurement electrode diameter of 0.55 mm could measure 100% of the input voltage of 600 V up to a gap distance of 65 μm. It is revealed that the voltage without physical contact between the measurement electrode and the sample under test can be measured with this proposed method.

Direct Circuit Formation Technology using Electrophotography

The application of printing technologies such as screen printing and ink jets should be an alternative for circuit formation technology in photolithography. We conducted work on the electrophotography method, which is one of these printing technologies used for laser printers and copiers, among other devices. This technology can achieve mass production with a continuous process and can form a large area pattern. Moreover, this technology is advantageous for producing many different kinds of limited pattern areas because changing the pattern is easy. In addition, the technology is also highly advantageous for forming a high-density pattern because the stroke width depends on not the drops (e.g., ink jet) but on an electrostatic latent image and the particle size.Metallic wiring by electrophotography has problems with electrification of metallic particles and conductive wiring because of low temperature heating. We examined a method of direct patterning of metallic nanoparticles that were ion electrified in liquid by liquid development. Afterwards, the pattern was baked at a low temperature to make it a conductor. The results were that we achieved a formation and transcription of a fine metallic wiring pattern with a width of 10 μm on an organic substrate.

Characteristics of Development

Two-component development systems using magnetic carriers and tribocharged toner particles are well established in electrophotography for high-quality development of electrostatic latent images at high speed. Two main approaches are used for these systems: development utilizing fixed magnets within a rotating developer roller, or development with a moving magnetic field, usually produced by a developer roller with a rotating magnetic core as well as a rotating outer surface or shell. The magnetic field from the rotating magnetic core provides a large amount of kinetic energy to the carrier and the toner particles moving toward the electrostatic latent image. Development to completion has been obtained with a rotating magnetic core development system. Completion is characterized by proportionality between the cube of the toner-charge-to-mass ratio, Q/m, and the voltage to completion, Vc, which is the difference between the developer bias and the voltage of the developed image.

Electrical Properties of a Magnetic Brush Using a High Resolution Field Probe

Dry powder xerographic marking systems are capable of high quality printing but there is still need to improve their capabilities to better compete in offset markets. Many of these systems use two component magnetic brush technology to develop latent electrostatic images. The electrical properties of the developer material which makes up the magnetic brush play a large role in the quality of the developed image. Our desire to improve image quality characteristics affected by development has led us to explore the magnetic brush in more detail.We have used a high resolution electric field probe to characterize the dielectric constant and conductivity of a two component developer in a magnetic brush. Standard techniques use large area cells which look at the integrated properties of the developer material and cannot resolve variations at the spatial scales that are relevant for image uniformity. Magnetic brush structure is likely to translate into local electric field variation during the development process producing variations in toned image density on the photoreceptor and ultimately in the final printed image. Variations in electrical properties due to position in the development zone and magnetic field are looked at and discussed in the context of image quality. Realistic particle simulations are compared to experimental data.