Electronic paper and electronic ink knowledge spread

What is electronic paper and electronic ink?

Electronic paper, also called digital paper. It is an ultra-thin, ultra-lightweight display that understands "a thin, soft, rewritable display that is paper-like." When it comes to electronic paper, electronic ink will inevitably be discussed. Graphically speaking, electronic paper is a thin film, and a layer of charged material "coated" on the film. This is electronic ink. This can also be seen as a thin embedded remote control panel. It has the following features: (1) Rewriting of content. Can rewrite or update any text or image, and browse a lot of content; (2) It is suitable for reading with the naked eye. Because of the high contrast, the text and images are clear and there is no change in any direction. Reading is comfortable. (3) Portability. Due to its light weight, the film is easy to carry, and can be folded and curled moderately. (4) It can maintain the display for a long time even when the power is off, and it is very energy-saving when used.

Various kinds of printed matter such as books and magazines and newspapers are being digitized, and the development of terminals for digital reading is also in progress. The problem in this area is how to make the reading and reading feel similar to the feeling when using paper. Only "electronic paper" does not constitute a display. As a necessary condition, it also includes ensuring compatibility between the image portion and the non-image portion, that is, legibility, and the ability to eliminate or rewrite the original text, save the image, and save energy.

This type of product is called "electronic paper," "digital paper," or "paper-like display." The goal is to create a paper-like product. The research has been conducted in two aspects. One is to make the display as a paper-like electronic screen that is "liquid crystal mode" or "electrophoretic mode", and the other is to change the content of the paper like a display. "Rewritable paper."

1. LCD mode

This method utilizes the property of the liquid crystal whose molecular arrangement is changed after the voltage is applied, and the contrast is expressed by adjusting the light transmittance and changing the direction of the light. Liquid crystal displays on notebook computers and other products are well known to us. The production idea of ​​the electronic paper liquid crystal display device is to separate the liquid crystal panel from the device portion that writes the image in order to achieve thinning and light weight, and to be able to curl and do things like the imaging paper. Writing can be achieved by various methods such as application of light, heat, surface charge, and the like.

2. Electrophoresis

This method realizes image display using microcapsules capable of changing the black-and-white state under voltage. The charged white titanium oxide particles and black toner particles in the microcapsules move up and down under a voltage to draw a black and white image. It is characterized by good contrast, brightness, vision, etc., low power consumption, light weight, easy to make it thin, free shape and so on. In addition, some products use the electrophoretic phenomenon of the charged toner to increase the contrast between black and white by increasing the density of the toner.

3. Rewrite paper

By using a thermal recording technique commonly used for products such as fax paper, dyes that are colored or decolorized at a specific temperature are used, thereby realizing graphic rewriting. Regardless of visual or sense of use, the product is almost no different from plain paper. This rewriting technique has been applied to point cards in electric supermarkets and monthly tickets for electric cars.

4. Reading terminal

The reading-only terminal has entered a practical stage. Companies have started to sell equipment for reading books, magazines, and other materials—reading-only terminals. Some of them use microcapsule-based electrophoretic displays. For example, SONY does LIBRIE. Since no electricity is consumed when the screen is not rewritten, using four alkaline batteries sold in the market, you can flip through a 10,000-page book with a resolution of 170ppi, a thickness of about 13mm, and the weight dropped to 200g for the first time. In addition, the aircraft can also play the characteristics of digital technology, to achieve sound reproduction, is expected to be used for language learning and other aspects. Now only monochrome products are displayed, and the price is as high as 40,000 yen (equivalent to about RMB 3,000). In addition, devices for displaying colors using a paper-like bendable display or an RGB color filter are also being developed. It can be said in the future that a part of the current paper print will be replaced by this electronic display method. If so, not only the production of existing prints can be replaced, but also the use of the same data to produce and provide electronic information content and other services will become necessary.