Electronic paper summary and toner display

Preface

Entering a highly-informed society in the 21st century, human beings are planning to achieve a comfortable and ample social life in order not to be subjected to external pressure, and they can achieve a smooth interface between people and information, and combine the strengths of paper with electronic display panels. The new expression media of strengths is digital paper or electronic paper. Digital paper has been defined as thermal rewriting media and words containing electronic paper. The characteristics of this digital paper are as follows:
Digital paper can be read or written anywhere at any time.

Intelligence rewriting: Any text or image can be rewritten.

Suitable for reading with the naked eye: rarely irritates the naked eye from the display surface.

Portability: Because the film is lightweight, it is portable and adaptable.

Maintaining the image: In the absence of electricity, the display can be maintained for a long time.

One. Display principle

It is a display that combines physical and chemical phenomena.

Physical aspects:

molecular

Optical Anisotropic Layered Cholesteric Liquid Crystals

Dye Molecular Alignment - Dichroic Dye Liquid Crystal Resin

particle

Particle Movement - Microcapsule Electrophoresis, Toner Display Board

Particle Rotation - Twist Ball

Phase Change - Transparent White Turbidity Rewrite

Chemical aspects:

Hair color - colorless dye rewrite

Photochromic

Second, the form of electronic paper

There are two forms of electronic paper that can be considered. One of these forms, just like the paper used today, is a rewrite paper that can rewrite letters and images multiple times. Re-write paper is used in the same way as current hard-copy printers use non-impact printers. As long as the printer is supplied with rewriting paper, it erases all of it first, and then writes the information. The user does not feel that the image has been erased at all and is used like usual paper. The second form is a thin-film display panel that is easy to carry, and it is hoped that a reflection type display that does not make the eyes feel tired even when staring at them for a long time. With a CPU and a semiconductor memory, it can be read by pressing a button. Electronic books and e-books. And hope to hang with the network, so that arbitrary access.

(1) Display, recording device separation type

Re-entry paper consisting of rewriting possible display layers and base paper is combined with a printer for erasing records. To erase records, thermal heads, ion currents, needle electrodes, liquid crystal panels, etc. are provided.

(2) Display, recording part integrated

The display layer and the control film are integrated into a thin film display panel.

Three. rewritable marking (rewritable marking)

As a currently published rewriting technique, a transparent white turbid type rewriting mark and an achromatic erasing type rewriting mark using a colorless dye, which are all thermal recording methods, are recorded by a thermal head. In the transparent white turbid type, fine particles of fatty acid are dispersed in the polymer film and heated to 110°C or higher, and the resin expands due to melting of the fatty acid. Thereafter, the fatty acid is cooled down, and the fatty acid is in a state of being in a liquid state, and the expanded resin is solidified. Thereafter, the fatty acid cures and shrinks to become polycrystalline fine particles, a gap is formed between the resin and the fine particles, and light is scattered by the voids to appear white. Next, when the heating is performed within the temperature range of 80 to 110°C, a part of the fatty acid is melted, and the resin thermally expands to fill up the voids. In this state, it is cooled and becomes a transparent state, achieving elimination of images. Rewriting marks using leuco dyes utilize reversible coloration and decolorization reactions between a colorless white dye and a sensible decolorizer with a long chain alkyl group. By heating with the thermal head, the leuco dye reacts with the decolorizing agent to form a color, and it is quenched as it is, and the colored state can be maintained. Then, after the heating is slowly cooled, the phase separation occurs due to the self-agglomeration of the long-chain alkyl group of the decolorizing agent, and the leuco dye and the decolorizing agent are isolated by physical action and achromatized.

Four. Electronic paper

(1) Microcapsule electrophoresis

This technology was originally developed by the United States MIT and E-Ink company. In the transparent microcapsules, blue liquid and white microparticles are placed, and white particles are electrophoresed according to the applied voltage to display images formed by white and cyan. The fine particles of titanium oxide used in the white particles are charged and stably dispersed in the blue insulating liquid. This microcapsule was coated with a silicone adhesive as an adhesive on a film with an ITO electrode. After the negative charge pattern is applied to the surface by ion flow, the white particles move to the lower part of the microcapsules, so that a blue image is drawn from the surface, and then the full charge of positive charge causes the white particles to move to the microcapsules. At the top, the surface becomes white and the image is erased.

(2) Turn the ball

Xerox Corporation and 3M Corporation of the United States jointly researched and developed the electronic paper with twisted ball method. This is a method in which white and black spherical particles are painted on each half of the ball, the direction of which is controlled by the electric field, and the image is displayed by white and black. Two-color particles are coated on the film with silicone resin as a binder, and cavities are formed around the particles and filled with a specific liquid. The white side of the particle surface is negative, and the black side is positive, showing a difference between the two colors. The charge forms a dipole. If a negative charge pattern is applied to the surface of this paperboard, the particles will rotate so that the black hemisphere will face upwards. If a positive charge is applied to the surface of the paperboard, the white hemisphere will face upwards so that an image can be displayed.

(3) 2-color dye liquid crystals

For the recording-type dome-shaped liquid crystal molecule A, a dichroic dye is blended to form a peritectic state, and a voltage is applied to the liquid crystal to change the arrangement of the liquid crystal molecules and also to change the absorption of the pigment. On the ITO transparent electrode, a mixture of liquid crystal, dichroic dye, and resin was coated to a thickness of 6 μm. The pigment began to form an irregular direction and was gray. However, according to the ion current recording and writing image, the dye was oriented to generate a white image. record of. The media is then heated above 60°C and returned to the original grey state, so that the image can be erased. In contrast, if the corona discharge is turned into a white state first, the thermal head may be used for thermal writing to form an image. This technology has been studied by Dainippon Printing Corporation and Tokai University.

(4) Liquid Crystal Organic Photosensitive Composite Film

In the absence of an electric field, cholesteric liquid crystals are oriented in parallel, and the color light is selected for reflection by accommodating the helical pitch of the liquid crystal. In the weak electric field, the focal conic orientation becomes, and light is transmitted to maintain its state. If the electric field is further strengthened, the parallel orientation is returned. With this change of electric field, display and non-display can be controlled. To write to the media, simply laminate the organic photoconductive film to control the partial pressure of the liquid layer. It can display 600dpi pattern or 8-point text, and can be further made into A6 on-demand media. It is reported that RGB can be overlapped to display color.

(5) Toner display board

Between two glass plates with ITO transparent electrodes, filled with black powder and white particles applied voltage, the black powder moves between the electrodes, showing black and white, the black powder is used conductive powder, white particles It is easy to slide fluorocarbon particles. A charge transport layer is coated on the ITO electrode, which functions to inject positive charges from the electrode into the toner. The black powder contacting the lower electrode is charged by charge injection from the charge transport layer, and moves toward the upper electrode due to a coulombic attraction force with the negative charge of the upper electrode. At this time, the white powder layer is drilled and moved to the black powder of the upper electrode, and the charge transport layer is used as an insulating layer and is attached by Coulomb force.

At this time, when viewed from the above, it is black, and then the polarity of the applied voltage is switched. Then, the black powder moves toward the lower electrode and adheres to the charge transport layer on the lower electrode. At this time, white particles are seen from above. It is white. By changing the polarity of the applied voltage in such a way, black or white can be displayed.

Conclusion

In the 21st century Internet era, people are looking forward to having rewritable paper and manuscript paper with the same softness as paper. Electronic notebooks made of portable electronic paper were born, and the rewriting paper and paper had almost the same texture. It can be repeated many times on the printer. Because it is used in the same form as today's hard copy, it is easily accepted by users. Moreover, electronic notebooks made of electronic paper bundles can also provide access to digital data and can store information through records. Because of so many uses, people are eagerly looking forward to the emergence of electronic paper.