Large flat-screen televisions for digital broadcasting are currently the focus of much attention. Heralded as the new generation of high-quality large flat-screen display, the SED (Surface-conduction Electron-emitter Display), jointly developed by Canon and Toshiba Corporation, is almost ready for practical application. Its greatest feature is the ability to produce vivid color images that surpass conventional types of display. Also, the SED delivers exceptional overall image quality—fast video-response performance, high contrast, high gradation levels—and low power consumption.
The advent of digital Hi-Vision broadcasting and the broadband network era, along with nextgeneration DVDs, digital cameras and digital video camcorders, is expected to fuel the spread of highdefinition, high-quality next-generation content. These trends have led to demand for larger screens and higher image quality. However, enlarging CRT (cathode ray tube) screens, today’s most common display, entails making the units significantly heavier and deeper. A major challenge facing display manufacturers has been how to develop a new kind of display offering the same picture quality as a CRT in a slim yet large unit. Canon’s SED has successfully met this challenge.
Display principle: Exceptional image quality achieved because of self-emitting screen
The SED, based on a new type of flat-panel display technology, was created through the merging of Canon’s proprietary electron-emission and microfabrication technologies with Toshiba’s CRT technology and mass-production tehcnologies for liquid crystal displays (LCDs) and semiconductors.
Like conventional CRTs, SEDs utilize the collision of electrons with a phosphor-coated screen to emit light. Electron emitters, which correspond to an electron gun in a CRT, are distributed in an amount equal to the number of pixels on the display.
Comparison of CRT and SED
The key to the electron emitters, at the heart of the SED, is an extremely narrow slit several nanometers wide between two electric poles. Electrons are emitted from one side of the slit when approximately 10V of electricity are applied. Some of these electrons are scattered at the other side of the slit and accelerated by the voltage (approximately 10 kV) applied between the glass substrates; causing light to be emitted when they collide with the phosphor-coated glass plate.
Structure of Electron Emitter
Since SEDs apply the same light emission theory as CRTs, they provide dynamic color expression, a sharp picture, and faster videoresponse than LCDs and plasma display panels (PDPs). In addition, SEDs do not require electronic beam deflection, making possible screens of more than 40 inches in size that are only several centimeters thick.
Emission efficiency: Low power consumption achieved due to high efficiency
Low power consumption is another main feature of the new display technology. SEDs convert electrical energy into light with a higher emission efficiency than other display types, resulting in power consumption that is two-thirds that of PDPs, and also surpasses CRTs and LCDs. In other words, SEDs are highly earth-friendly, meeting the needs of the times.
Production technology: Application of inkjet technology
With the application of inkjet printing technology to develop a high-performance electron emitter and a screen-printing method to produce matrix wiring, we are improving production technologies to manufacture large-screen panels at low cost.
Canon began SED research in 1986 and, in 1999, began joint development activities with Toshiba with the aim of commercializing an SED product. Canon and Toshiba, deciding that the joint development had a definite future, established a joint venture company SED Inc. in October 2004. Plans for the new company call for the commercialization of SED panels primarily for largescreen flat-panel televisions. Preparations to start production are currently underway.
taken from canon.com