SURFACE CONDUCTION ELECTRON EMITTER DISPLAY

The SED has been developing since 1987. The flat panel display technology that employs surface conduction electron emitters for every individual display pixel can be referred to as the Surface-conduction Electron-emitter Display (SED). Though the technology differs, the basic theory that the emitted electrons can excite a phosphor coating on the display panel seems to be the bottom line for both the SED display technology and the traditional cathode ray tube (CRT)televisions. When bombarded by moderate voltages (tens of volts), the electrons tunnel across a thin slit in the surface conduction electron emitter apparatus. Some of these electrons are then scattered at the receiving pole and are accelerated towards the display surface, between the display panel and the surface conduction electron emitter apparatus, by a large voltage gradient (tens of kV) as these electrons pass the electric poles across the thin slit. These emitted electrons can then excite the phosphor coating on the display panel and the image follows. The main advantage of SED’s compared with LCD’s and CRT’s is that it can provide with a best mix of both the technologies. The SED can combine the slim form factor of LCD’s with the superior contrast ratios, exceptional response time and can give the better picture quality of the CRT’s. The SED’s also provides with more brightness, color performance, viewing angles and also consumes very less power (Fig.1.1(a)). More over, the SED’s do not require a deflection system for the electron beam, which has in turn helped the manufacturer to create a display design, that is only few inches thick but still light enough to be hung from the wall (Fig.1.1(b)). All the above properties has consequently helped the manufacturer to enlarge the size of the display panel just by increasing the number of electron emitters relative to the necessary number of pixels required. Canon and Toshiba are the two major companies working on SED’s. The technology is still developing and we can expect further breakthrough on the research.

HISTORY

Canon began SED research in 1986 and, in 2004, Toshiba and Canon announced a joint development agreement originally targeting commercial production of SEDs by the end of 2005. The 2005 target was not met, and several new targets since then have also slipped by. This failure to meet mass-production deadlines goes as far back as 1999, when Canon first told investors of its intentions to immediately begin mass-producing the technology. The lack of tangible progress has worried many investors and has prompted many critics. One critic called SED “the best display technology you’ve ever seen that may be stillborn”. During the 2006 Consumer electronics show in Las Vegas, Nevada. Toshiba showed working prototypes of SEDs to attendees and indicated expected availability in mid-to-late 2006. Toshiba and Canon again delayed their plan to sell the television sets to the fourth quarter of 2007. At the 2007 Consumer Electronics Show, no SED displays were to be found on The show floor. This led many analysts to speculate that the technology would never reach the consumer market.

                    

In October 2006, Toshiba's president announced the company plans to begin full production of 55-inch SED TVs in July 2007 at its recently built SED volumeproduction facility in Himeji. In December 2006, Toshiba President and Chief Executive Atsutoshi Nishida said Toshiba is on track to mass-produce SED TV sets in cooperation with Canon by 2008. He said the company plans to start small-output  production in the fall of 2007, but they do not expect SED displays to become a commodity and will not release the technology to the consumer market because of its expected high price, reserving it solely for professional broadcasting applications.                     

                    

The formation of SED Inc. in 2004 was certainly an acknowledgement by Canon that, no matter how good their engineering and technical prowess, they would have a difficult time manufacturing and mass-marketing this technology on their own. While CES 2005 was the moment for SED to prove its technology was alive and kicking, CEATAC 2005 and CES 2006 showed that SED Inc. could make multiple versions of that same 36-inch display with repeatable image quality and consistency. Hopefully we will see a Canon SED TV display at bo September 30th and CES2009 in Las Vegas next January. Canon has a reissue patent covering SED TV technology. United States Patent RE40, 062 was reissued February 12, 2008. It apparently has some modifications from previous SED TV patents. This may be the beginning of Canon’s attempt to produce SED panels without using the Nano-Proprietary patented technology.

ADVANTAGES

SEDs promise the same advantages over LCDs and Plasmas as CRTs are delivering today plus they will also be thin and much larger than CRTs.

1) SED TV Compared to CRT

SED is flat. A traditional CRT has one electron gun that scans side to side and from top to bottom by being deflected by an electromagnet or "yoke". This has meant that the gun has had to be set back far enough to target the complete screen area and, well, it starts to get ridiculously large and heavy around 36". CRTs are typically as wide as they are deep. They need to be built like this or else the screen would need to be curved too severely for viewing. Not so with SED, where you supposedly get all the advantages of a CRT display but need only a few inches of thickness to do it in. Screen size can be made as large as the manufacturer dares. Also, CRTs can have image challenges around the far edges of the picture tube, which is a non-issue for SED.

2) SED TV Compared to Plasma TV

Compared to Plasma the future looks black indeed. As in someone wearing a black suit and you actually being able to tell it's a black suit with all those tricky, close to black, gray levels actually showing up. This has been a major source of distraction for this writer for most display technologies other than CRT. Watching the all-pervasive low-key (dark) lighting in movies, it can be hard to tell what you're actually looking at without the shadow detail being viewable. Think Blade Runner or Alien. SED's black detail should be better, as Plasma cells must be left partially on in order to reduce latency. This means they are actually dark gray – not black. Plasma has been getting better in this regard but still has a way to go to match a CRT. Hopefully, SED will solve this and it's likely to. Also, SED is expected to use only half the power that a Plasma does at a given screen size although this will vary depending on screen content.

DISADVANTAGES

As with any phosphor-based technology, SED may also be susceptible to screen burn-in. This was a constant problem for people using CRT television monitors for security camera systems. Early plasmas also had this problem, but with phosphor development, the problem has largely been reduced.