What is printing?
The process of reproducing text and images using a master form or template, usually with the help of an external device called a printer that accepts text and graphic output from a computer and transfers the information to a surface. Printing can be traced back to early times where cylinder seals were used to imprint images on clay, and modern printing is typically done by using ink on paper (but can also be done on metals, plastics, composite materials and more).
There are many printing technologies, which can be divided into two main categories: impact and non-impact.
Impact printers include a mechanism that touches the paper to create an image. The two main impact technologies are Dot Matrix, in which small pins strike a ribbon coated with ink and cause the ink to transfer to the paper, and Character, which involves a ball with letters embossed on it striking against the ink ribbon and leaving an impression.
Non-impact methods do not touch the paper to create an image. Several methods are included in this category, like inkjet printers that use nozzles to spray drops of ink on the paper, laser printers that use dry ink, static electricity and heat to bond ink onto the paper, solid ink printers, dye sublimation and more.
Common methods of printing include: letterpress, offset lithography, flexography, gravure, screen printing and digital printing (which includes different methods like toner, magnetic digital print, laser and inkjet).
OLED (Organic Light Emitting Diodes) is a flat light emitting technology, made by placing a series of organic thin films (usually carbon based) between two conductors. When an electrical current is applied, light is emitted. OLEDs can be used to make displays and lighting, with possible applications that span TV sets, computer screens, mobile phones, decorative lighting and more. Since OLEDs emit light they do not require a backlight and so they are thinner than LCD displays, and are also more efficient, simpler to make and boast a better color contrast.
While OLED displays excel in color-contrast and efficiency compared to LCDs, they’ve also proven relatively hard to produce on a large scale. Current evaporation-based production techniques involve a lot of wasted material and risk of defects. OLEDs are also extremely sensitive to moisture and oxygen and therefore must be protected with a high performance encapsulating layer. All of these issues hinder OLEDs’ market takeover, but much work is put into resolving them.