LCD 的危機 –SED

http://www.canon.com/technology/detail/device/sed_display/

Large, Slim Displays with Image Quality on Par with CRTs

The advent of the high-definition TV and the broadband network era has 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 display manufacturers are facing 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 (Surface-conduction Electron-emitter Display) has successfully met this challenge.

A Slim Structure Positioning Multiple Electron Emitters

The SED consists of a glass plate mounted with electron emitters, similar to a CRT\’s electron gun, in an amount equal to the number of pixels on the display. Positioned next to it is another glass substrate coated with a fluorescent substance. Between the two glass plates is a vacuum. The key to the electron emitters at the heart of the SED is an extremely narrow slit (several nanometers* wide) made from ultrafine-particle film between the two electric poles. Electrons are emitted from one side of the slit when 16 to 18 volts of electricity are applied. Some of these electrons are scattered at the other side of the slit and accelerated by the voltage (approximately 10kV) applied between the glass plates, and they collide with the fluorescent-coated glass plate, causing light to be emitted.

Providing Clear and Bright Images with Low Power Consumption

Comparison of CRT and SED

The electrons released by the tunneling effect scatter, and collide with the phosphor when accelerated by the application of voltage. As each color emits light when electrons collide with the coating of the phosphor divided into RGB, a light source like an LCD backlight is not required. Since SEDs apply the same light emission theory as CRTs, they can provide dynamic color expressions, a sharp picture, and perform faster video response than LCDs and plasma display panels (PDPs). In addition, SEDs do not require electronic beam deflection unlike CRTs, which makes it possible to create screens of more than 40\” in size that are only several centimeters thick. Low power consumption is another main feature of the new display technology.

SEDs convert electrical energy to light with an emission efficiency of 5 lumens (lm)/W or higher, resulting in energy consumption that is roughly one-third that of PDPs, and also surpasses CRTs and LCDs. In other words, SEDs are highly environment-friendly displays that meet the needs of the times.

Various Technologies Enabling an Efficient Production

Applying 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 researching a certain type of electron emitter in 1986. Using this emitter technology, we developed a small SED pilot unit, which offers excellent potential as a large and thin emissive display, in 1996. In 1999, we signed a codevelopment agreement with Toshiba Corporation, and our efforts are now targeting preliminary production of a large SED.