Field emission display

Field emission display

The full name of FED in English is Field Emission Display, that is, field emission display. According to the electron emission source, FED can be divided into CNT (carbon nanotube type), SED (surface conduction type), Spindt (conical emitter type), BSD (ballistic electron emission type) and other types. At present, the most promising applications are mainly CNT and SED technology systems.

Introduction In the past, FED encountered many bottlenecks in the development, but from the application of carbon nanotube technology gradually rose to the floor, and the two companies CANON and TOSHIBA are also joint ventures to develop with SED technology. It seems that the end of FED still has Its potential.

Various flat panel display technologies have replaced CRT as the development goal in terms of image quality and cost, and Field Emission Display (FED) is developed with the extension of CRT technology, intending to seize this market with the advantages of CRT, Although it is similar in concept to CRT, it is still different from CRT technology in structure and material, so it still encounters many bottlenecks in its development. However, the use of nanotube technology in field emission display technology gradually has Large breakthroughs and developments, coupled with Canon and Thoshib ’s theory of using surface conduction to emit electrons to develop SED technology, a joint venture was established in October 2004 to develop, manufacture and sell SED panels. It is expected to be in August 2005 Mass production started, and people are looking forward to the new turn of the FED technology.

The principle of FED technology and the development of the field emission electrode theory were first proposed by RHEowler and LWNordheim in 1928. However, the field emission electrode element was developed based on semiconductor process technology, and the field emission electron was used as the display technology. It was developed by CASpindt in 1968. It was proposed to subsequently attract subsequent researchers to invest in research and development.

However, the application of the field emission electrode was not really noticed until after the French LETI CHENG company exhibited a finished display using the field emission electrode technology at the 4th International Vacuum Microelectronics Conference in 1991. And attracted Candescent, Pixtech, Micron, Ricoh, Motorola, Samsung, Philips and other companies to invest, FED also joined the ranks of many flat panel display technologies.

In the field emission display application, there is a vacuum belt between the transmitting and receiving electrodes. Therefore, a high voltage must be introduced into the transmitting and receiving electrodes to generate an electric field, so that the electric field stimulates electrons to hit the phosphor under the receiving electrode, and a luminous effect is generated. The principle of this kind of light emission is similar to that of a cathode ray tube (CRT), in which electrons hit the phosphor in a vacuum to emit light. The difference is that the CRT is emitted by a single electron gun and is controlled by a deflected orbit (DeflaTIon Yoke) The scanning direction of the electron beam emission, and the FED display has hundreds of thousands of active cold emitters, so the FED can achieve a space-saving effect than the CRT in construction. Secondly, the voltage part, CRT needs about 15 ~ 30KV working voltage, and the cathode voltage of FED is about less than 1KV.

Although FED is regarded as a desirable technology for CRT, it cannot be compared with the cost of CRT in the early stages of development, mainly because of field emission components. Although the Spindt-type micro-scale array was first proposed to realize the emission display technology, its array characteristics limit the display size. The main reason is that its structure includes a circular hole on each array unit. It contains a metal cone, and the lithography and evaporation techniques will limit the size during the production process.

The solution is to replace the Spindt field emission element technology. In 1991, when NEC published an article on carbon nanotubes, the researchers found that graphite synthesized with nanostructures, or carbon nanotubes as field emission elements can Get better field emission efficiency, so nanotube synthesis technology has become a new direction for FED research and development.

At present, in the field of nanotube field emission displays, Ise Electronics of Japan and Samsung of South Korea have invested earlier, and manufacturers such as SONY, Hitachi, Fuji Photo, Canon, Panasonic, Toshiba, Nikon and NEC have also proposed to be related to nanotechnology. Patent application, in which nano carbon tube is the main R & D project.

The large-scale field emission display panel is the first to promote Japan's Ise Electronics. The company has successfully used chemical vapor deposition to produce a 14.5-inch color nanotube field emission display with a brightness of 10,000cd / m2. In addition, Samsung in South Korea Announced a monochrome, 600cd / m2 15-inch carbon nanotube field emission display, and plans to develop a 32-inch nanometer carbon tube field emission display used in TV sets to successfully achieve low-voltage drive results below 100 volts.

1. Canon and Toshiba develop SED TV
In field emission display technology, Canon and Toshiba are developing surface-conduced electron emission displays (Surface-conducTIon Electron-emitter Display.SED). The technical principle of SED is mainly to use surface conduction to emit electrons. The difference between SED and CNT FED is that SED has the advantages of lower driving voltage, no need for coking electrode, and higher uniform brightness. Without a focusing electrode, the cost of the process can be effectively reduced, and the uniformity of brightness is a problem of thick film FED, because the uneven thickness of the film means that each pixel is at the same voltage, and the currents encountered are not equal, resulting in brightness on the screen Unevenness.

Table 1 SED and CNT FED technology difference technology SED CNT FED
Advantages 1 The efficiency of the source is more uniform and the brightness is more uniform.
2 The driving voltage is small
3 No focusing electrode is required. 1 Higher emission efficiency.
2 It is easier to build an army structure.
Disadvantages 1 Crack control is not easy, resulting in difficulty in improving yield.
2 The efficiency of electron emission is poor. 1Emission source control is not easy, and the brightness is not uniform.
2 The driving voltage is high.
3 The electron beam is easy to expand and requires a focusing electrode.

Table 2 Various display technology performance comparison technologies FED LCD PDP CRT
Power consumption â—Ž â—‹ â–³ â–³
Weight â—Ž â—Ž â—Ž â–³
Size-â—‹ â—Ž â—‹
Fineness â—Ž â—Ž â—‹ â—Ž
Operating environment â—Ž â—‹ â—‹ â—Ž
Brightness â—Ž â—‹ â—‹ â—Ž
Coordination â—Ž â—‹ â—‹ â—Ž
Color purity â—Ž â—Ž â—‹ â—Ž
Reaction speed â—Ž â–³ â—Ž â—Ž
Angle of view â—Ž â–³ â—Ž â—Ž
Process-â–³ â—‹ â—Ž
Material cost-â–³ â—‹ â—Ž
Drive circuit â—Ž â—Ž â–³ â—Ž

In terms of cost, according to Canon and Toshiba, the material cost of the drive circuit of the SED panel is similar to that of the LCD panel, and the material cost of the panel itself is equivalent to that of the PDP. Therefore, overall, it has cost advantages over LCD and PDP. In the initial stage of mass production, the fixed cost is higher, but Canon and Toshiba plan to reduce the cost of this part by 2010 to compete with other technologies.

2. The development of nanotube field emission in backlight modules In recent years, due to the relatively high cost of backlight modules for large-size LCD TVs, which has hindered the space and speed of the overall cost reduction, the development of the North Light Source in addition to the original cold cathode In addition to lamps, light-emitting diodes (LEDs), planar light source technology, and nanotube field emission technology have all begun to be developed for large-size liquid crystal panels.

In the development of nanotube carbon field emission backlight modules, Samsung Corning and LG Electronics of South Korea are currently investing in development, and the Taiwan Institute of Industrial Research Institute of Electronics will also develop samples of nanometer carbon tube field emission backlight modules. The Japan Nikkiso Co., Ltd. also exhibited samples of nanotube field emission backlight modules in January 2005.

Nikkiso and Japan Displaytech21 jointly developed a liquid crystal panel backlight module using carbon nanotubes in January 2005. The screen size of the sample exhibited this time is 3 inches. The technical principle is to use a glass substrate coated with a nano carbon tube as a cathode, and a glass substrate coated with a fluorescent material to form an anode, overlapping with a certain space, and using the nano carbon tube as an electron emission source. The emitted electron photo shoots on the fluorescent material, and then emits white light. The used carbon nanotube has a diameter of 20 NM, and is a multi-layered carbon nanotube with a smaller diameter carbon nanotube in one nanotube. The electric field intensity at the beginning of light emission is 0.74V / um, which is lower than the previous general 1 ~ 2V / um. Since the electric field intensity of the light emission can be reduced, the voltage applied between the carbon nanotube and the positive electrode can be reduced , To achieve the purpose of reducing power consumption. When used as a 32-inch TFT LCD backlight, the brightness is about 60W when it emits light at 10.000cd / m2. Compared with the use of CCFL and LED, the power consumption is lower. When it is expected to reach the practical level in 2006, the goal is to achieve a real brightness of 30,000cd / m2 and a lifespan of 50,000 hours. In terms of application, it is based on small and medium-sized LCD panels for mobile phones and vehicle-mounted terminal products. In the future, the plan will be developed to large-scale product fields such as large-screen LCD TVs and lighting equipment.

Manufacturer News
In the development of field emission displays, Ise Electronics of Japan and Samsung of South Korea invested earlier, but nanotechnology gradually paid attention to manufacturers, and the number of invested companies gradually increased. Sony, Hitachi, Fuji Photo, Canon, Panasonic, Toshiba, Nikon Manufacturers such as NEC also filed patent applications related to nanotechnology, with nanotubes as the main R & D project.

1. Ise Electronics
Ise Electronics of Japan showed a field emission display using carbon nanotube material at the SID conference as early as 1998. The emission current is about 200MA. Ise Electronics successfully produced a 14.5-inch color nanotube field emission display with a brightness of 10,000 cd / m2 using chemical vapor deposition at the end of 2001, and exhibited the use of nano at the Tokyo International Forum in March 2002 The 40-inch wide-screen field emission display of Mi Carbon Tube makes ISE Electronics the fastest-growing manufacturer of nano carbon tube field emission displays.

2. Canon / Toshiba
Canon and Toshiba used the theory of surface conduction to emit electrons to develop SED. Canon and Toshiba signed a contract in June 1999 to jointly develop the next-generation large-screen display technology—Surface-conduced Ton Electron Display (Surface-conducTIon Electron- Emitter Display)}, mainly used in 40-inch large-size displays. Canon is mainly responsible for the two technologies of electron emission and micro-manufacturing. Toshiba has extended its development with display technologies such as CRT and LCD, and plans the process technology required for mass production.
Toshiba exhibited SED trial products at CEATECJAPAN2004, the black brightness is 0.004cd / m2 (Toshiba measured LCD TV is .7cd / m2), the white brightness is 260cd / m2 (PDP is 0.7cd / m2) (PDP is 60cd / m2), Emphasize the super performance of SED in contrast.
Canon and Toshiba announced a joint venture to produce SED displays in September 2004. The new company SED Co., Ltd. is engaged in R & D, production and sales of SED technology. It began operations in October 2004 and is expected to invest US $ 18.3 billion to build SED production lines. Invested US $ 16.4 billion in mass production. The products are mainly used in large-size TVs of more than 32 inches. It is expected to start small-scale mass production of 50-inch SED panels in August 2005. The monthly output is about 3,000 pieces. It is expected that the production capacity will be expanded to With a monthly output of 75,000 pieces, the production capacity was increased to 1.8 million pieces per year in 2008 (about 150,000 pieces per month), and in 2010 it was increased to 3 million pieces per year, with a production scale of 250,000 pieces per month.
In terms of sales target, it reached 30 billion yen per year in 2007 and 200 billion yen per year in 2010.

3. Futaba Electronics
Japan Futaba Electronics successfully developed an inch-color FED panel in October 2002, and exhibited 8 trial products in the same year at CEATEC JAPAN 2002, which showed 16.7 million colors, a brightness of 400cd / m2, and power consumption It is 4W, and the panel thickness is only 2.8mm. The drive circuit module of FED is developed in cooperation with Murata Manufacturing Co., Ltd. However, the FED panel on display is still in the research and development stage, and the date of production has not yet been decided.
In February 2003, NanoTech 2003 Futaba Electronics also demonstrated the nanotube field emission display, resolution 16x16 pixels, each pixel size is 4mm x 3 mm, pixel gap is 2mm, brightness can reach 1.000cd / m2, cathode The voltage is 200 volts and the power consumption is 7W.
In July 2004, 4 inch to 11 inch full-color FED products of various models were displayed, of which 4 inch (resolution 240X64 pixels) and 4.3 inch (resolution 240X128 pixels) products, characterized by brightness up to 1.000cd / m2, other products Specifications, 5.9QVGA, brightness 800cd / m2, 8.0 inch WQVGA (resolution 480X234 pixels), brightness 500cd / m2, 11.3 inch VGA, brightness 350cd / m2.
Futaba Electronics released its FED production plan in November 2004. It is expected to produce about 11-inch automotive panels. The plan invests 8.5 billion yen in its production equipment. The production line was set up in 2006 and mass production began in 2007. The estimated revenue is 6 billion yen.

4. Sumsung
Sumsung SDI has been co-developing FED with the Sumsung Institute of Technology since the mid-1990s. The 12th International Vacuum Microelectronics Conference was held in Germany in July 1997. A 4.5-inch, 2.2mm thick, 800-volt working voltage, brightness It is 350cd / m2, and began to issue 18-inch FED samples in 2000. In 2001, a monochrome 15-inch carbon nanotube field emission display was also published, with a brightness of 600cd / m2.

Table 3 Canon and Toshiba joint venture SED company name SED Co., Ltd. Date of establishment October 2004 Business content Development, production and sales of SED panels Location of the company 9-22-5 Tamura, Hiratsuka City, Kanagawa Prefecture
Company Representative Representative President and President: Junichi Uzawa (now Canon Director and Director of SED Development)
Capital amount 1.05 billion yen Shareholder structure Canon accounts for 50.002%, Toshiba accounts for 49.998%
Number of employees About 300 (January 2005)

Sumsung Advanced Institute of Technology's FPD International 2004 in 2004 also emphasized the advantages of nano carbon tube field emission displays with carbon nanotubes as the electron source, and is ready for mass production in 2-3 years.

5. LG Electronics
LG Electronics and the Display Research Institute of the LG Institute of Comprehensive Technology developed the 5 to 6-inch FED in 2001. In 2002, it successfully developed a 20-inch field emission display and has plans to commercialize the FED.

6. Institute of Electronics, Industrial Technology Research Institute
In August 2001, the Institute of Electronics Research and Industry Research Institute announced the development of the first Taiwanese 4-inch carbon nanotube plant emission display (CNT-FED), which is beneficial to the low conduction electric field and high emission current density of nanotube And high stability, combined with FED technology to achieve the possibility of flattening the cathode ray tube, retain CRT affects quality, and has the advantages of power saving and small size, becoming a large-sized flat panel display with low driving voltage and high luminous efficiency .
In addition to the application of nanotube field emission technology on the display, the Institute of Electronics Research and Industry Institute also announced in December 2004 that the development of the 20-inch Carbon Nanotube Field Emission Back Light Unit (CNT) -BLU), which is mainly used for the backlight of large-size TFT LCD. Currently, the large-size TFT LCD backlight module still uses cold-cathode lamp (CCFL) as the backlight, but the large-size (above 30-inch) TFT LCD uses CCFL The length needs to be longer, which is more difficult to produce than the lamps used in notebook computers and monitors in the past, and the problems of uniformity of the screen, mercury content, and expensive optical film make the large-size TFT LCD backlight module The cost of LED has been greatly increased. Although many manufacturers have developed towards LED backlight modules, the application of nanotube field emission technology to the development of backlight modules has the advantages of uniform light source intensity, high luminous efficiency, and simple manufacturing process. Mi carbon tube field emission technology has one more application direction.

7. TECO Nano Materials
In 2002, TECO signed a cooperation agreement with Nanoelectronics, Materials and Chemical Research Institute of Engineering Institute on materials, materials and products of carbon nanotube. Commercialized development of Yuan, and development of carbon nanotube displays for TVs.
TECO Nano Materials, a subsidiary of TECO Group, received a subsidy of RMB 30 million from the Ministry of Economic Affairs in 2002, together with TECO Group's investment in the development of carbon nanotube displays and related materials. In addition to borrowing heavy industry research institutes, and carrying out individual research projects with universities such as National Taiwan University, Qingda University, Jiaotong University, Central Government, and Central Plains.

8. Others
In terms of other manufacturers, Mitsubishi Electric has developed a carbon nanotube field emission display, which is expected to be commercialized in 2006. Motorola ’s R & D department, Motorola Labs, announced in July 2003 that it has completed the nanotube field emission display technology and demonstrated a 15-inch sample. However, Motorola intends to set up its own factory to produce FED, and plans to open up technical patents to Manufacturers interested in developing.

CANDESCENT Technologyd, San Jose, California, built a 340,000-square-foot factory, but due to technology and market demand, it announced that it would abandon the production plan of the field-fired shooting team display, preparing to license the technology to other companies, and will transform from a manufacturer Companies focused on intellectual property rights.

Home appliance manufacturers choose unique technologies to strengthen competitiveness
In terms of large-size thin TV technology, LCD TVs, plasma TVs, rear projection TVs, and emerging SED TVs, major home appliance manufacturers gradually believe that they have their own unique technology to provide cost, image quality and capacity in the fierce competition Sufficient support, so in the recent development of Japanese display manufacturers, there has been a trend of {selection and concentration}. For example, Sharp announced the construction of the seventh-generation factory after mass production of the sixth-generation factory. Samsung and LG.Philips LCD also announced the construction of the seventh-generation factory. Plan, and Hitachi transferred the plasma display manufacturing company FHP from the Fujitsu Group to its own group, and cooperated with Panasonic in the development of plasma displays in R & D, manufacturing process, and procurement of components. Although Sony denied to withdraw from plasma The operation of TV, but also emphasizes that LCD TVs and rear projection TVs are the main development technologies. Therefore, under this wave of {selection and concentration}, manufacturers have their own unique technologies to establish the advantages of manufacturer development.


Table 4 The layout of home appliance manufacturers on flat-screen TVs
Company Direct-view thin TV Rear projection TV (Microdisplay-based RPTV)
LCD TV PDP TV SED TV transmissive LCD DLP LCOS
Hitachi â—‹ â—Ž
JVC â—‹ â—‹ â—Ž
Mitsubishi â—‹ â—‹ â—Ž
Panasonic â—‹ â—Ž â—‹ â—‹
Sanyo â—‹ â—Ž â—‹
Sharp â—Ž â—‹
Sony â—Ž â—‹ â—‹
Toshiba â—‹ â—‹ â—Ž â—‹
Samsung â—Ž â—‹ â—‹ â—Ž
LG â—Ž â—Ž â—‹ â—‹
Philips â—Ž â—‹ â—Ž (Announced in 2004)
Note: â—Ž: Main product development; â—‹: Product development

At a press conference held on the day before the opening of [2005 International CES] in January 2005, Toshiba Digital Media Network Corporation President Miu Fujii talked about the strategy of [using SED and HD DVD as future strategic products]. Toshiba believes that SED has the advantages of high contrast, wide viewing angle, and fast response speed of CRT, and is lighter and thinner than LCD TVs, and lower power consumption, so it actively develops its unique SED display technology and applies it to large-size thin TVs.

in conclusion
The current development of field emission display technology seems to be not so mature under the pressure of the development of mainstream liquid crystal displays, plasma displays, and organic electro-laser displays, but nanotechnology is actively encouraged by governments of various countries. Development is expected to have more breakthroughs. The display industry, which presents a diversified development in technology, how to develop its own sky in the competition of many technologies, the future of field emission display technology still needs the continuous efforts of relevant manufacturers.

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