This chapter presents background knowledge on the display technologies and their development pathways leading up to the development of the flat panel television industry. This background knowledge is important for understanding the nature of uncertainty faced. It is also necessary for interpreting the analysis performed in the subsequent chapters of this dissertation.
The characteristics of the competing display technologies vary greatly.
Accordingly, the development pathways they traveled and uncertainties they faced also differed. Furthermore, suitability for the various non-TV display applications differed between the technologies. Some technologies were suitable for more applications – providing opportunity for further investment – than others. The technologies discussed in this chapter include those that have been commercially used in TV sets as well as some that have not but were thought to have potential to be used.
Introduction to Display Technologies for Flat Panel TV applications
This section describes the different display technologies competing for use in the flat panel TV application over the time period of the study. The intention here is to familiarize the reader sufficiently with the competing technologies so as to facilitate understanding of the detailed actions of the firms over the study period. Significant effort was made to ensure the study covered the relevant technologies. Appendix Two contains a typology of display technologies as further evidence of this effort.
The technologies described in this section include: liquid crystal, plasma, organic EL, field emission display and plasma addressed liquid crystal. The most common of these is liquid crystal.
When used in a display, liquid crystal materials work like shutters controlling light flow. A white light source behind the liquid crystal shines through the liquid crystal layer and a number of filters that are layered on the display glass. Applying different levels of electricity to small areas of the crystals causes them to change their orientation, blocking or unblocking the light from shining through. Figure 3-1 depicts the general principle for the typically used twisted nematic liquid crystal mode.
In color LCD panels, pixels on the display are made up of different colored sub-pixels (typically, red, green, and blue), each of which has a color filter and an associated switch to control the liquid crystal shutter. Closing all of the shutters on the sub pixels results in the pixel becoming black. Leaving them all open results in white. These switches used to control the liquid crystal make up a matrix across the display.
Each LCD cell is addressed through a matrix, which can be active matrix (AM- LCD) or a passive matrix (PM-LCD). However, active matrix is required for higher quality, higher resolution applications. Passive matrix proved unsuitable for applications like TV. Thin Film Transistor (TFT) is the primary active matrix technology, although diodes can also be used for active matrix switching.
Figure 3-1: Diagram of Twisted Nematic Liquid Crystal Cells
There are several sub-technologies belonging to TFT-LCD. These include: amorphous silicon (a-Si), low temperature poly-silicon (LTPS), and high temperature poly-silicon (HTPS). Amorphous Silicon is the predominant LCD technology today; it is used in flat panel televisions and a large variety of other applications. LTPS is capable of very high-resolution display, and has been used in high quality cell phones, cameras, and laptops. It has not been manufactured for very large screen applications. HTPS is also capable of very high-resolution display. HTPS are typically very small panels that are used in projection systems and near eye displays. With a few minor exceptions due to data availability issues, option-like investments in LCD are tracked at this sub-technology level in this dissertation.
Plasma display technology works in a way similar to florescent lighting. PDPs are made up of many sub-pixel cells, each containing electrical connectors, a gas, and a colored phosphor similar to those used in CRT displays. The color of the phosphor determines the color of the sub-pixel. When electricity flows, it causes the gas to become plasma, which in turn causes phosphors on the screen to glow. In order for the process to occur quickly enough to be useable in a TV, all of the cells need to receive a certain level of electricity even when they are dark. In the past, PDPs were developed using direct current and alternate current; however, direct current panels were found to have very short lifetimes, so this type was completely dropped by all firms in the industry.
Organic Electroluminescence (OLED) is a solid-state technology; electrical current is run to a cell containing OLED materials, which causes the cell to emit light. Color is achieved through one of two ways: white color OLED materials can be used with color filters, or red, blue, and green OLED materials may be used without filtration. One of the attractions of OLED to manufacturers has been its relative simplicity because it requires fewer layers than LCD and does not need a backlight. Like LCD, OLED cells are switched on and off by active or passive matrices. Active matrix is required for larger applications. OLED technology can be divided along the different kinds of OLED
materials used: small molecule materials and large molecule materials. Kodak has key patents for small molecule and Cambridge Display Technology (CDT) has key patents for large molecules.
Field Emission Display (FED) is similar to having many tiny CRTs next to each other. Each pixel has its own electron gun (emitter), which is fired across a small vacuum to light a phosphor on the screen. A large number of emitter types have been
developed by different firms interested in this technology. Many firms conducted R&D on this technology. Despite announcements that it would be used in television sets this has not happened.
Plasma Addressed Liquid Crystal (PALC) is another display technology briefly developed with the intention of being used in television sets. The general idea of the technology combined plasma and LCD. Plasma was used instead of TFT to drive the system and liquid crystals worked as shutters as with regular LCD panels. Development activities were limited to a small number of firms. Although PALC does not rank in the top potential flat panel television technologies in retrospect, it is of interest in that several firms did make option like investments in the technology.
This section has provided a brief introduction of the display technologies followed in this study. The section following considers the requirements for flat panel TV.
Potential Television Displays
There are a number of attributes of a display that make it more or less suitable for TV applications. These include: display size, image quality, energy requirements, lifespan, production requirements and production cost. These different requirements are considered below with regard to the major competing technologies. The bulk of this discussion focuses on three main competing technologies: LCD, PDP, and OLED. Each technology has moved along a different development trajectory and has faced different uncertainties over time.
Data on specifications of flat panel displays was gathered as evidence of how the different display technologies changed over time with regard to the attributes discussed below. No single source carried panel specifications for the entire period, and there was a period of several years in the middle of the study where data was unavailable. The Nikkei BP series carried panel specifications for the years 1994 through 1995. The Fuji Chimera series listed panel specifications for the years 2001 through 2007. Additional observations outside of this time frame were available from these same sources in several instances, allowing some observations as early as 1991. Unfortunately, there is a gap in coverage between these sources for the years 1999 and 2000. In the charts below, years with no data are represented by dashed lines connecting the points where data was available. The entire database of panel specifications gathered here has over 2,800 records.
Display size. Television sets come in a variety of different sizes, however the main TV of the household tends to be a larger one in the living room of the house. Early TFT-LCDs were small and expensive. Limitations to LCD size were due to issues with production quality (larger screen = higher potential for defects) and limited size of early production equipment. Costs were also an issue. Only relatively recently has production of large LCD panels become feasible.
PDPs did not face the same size-related technological barriers as LCD and were produced in large sizes from early on. The situation with PDP was the opposite of LCD. It was difficult to make large LCDs, and difficult to make PDPs small. PDPs are
comprised of many small cells each of which must hold a gas. It is more difficult to make small pockets than large. As a result, pixel size and display size started out large.
Chart 3-1 below depicts how the state of the art in terms of panel size changed over the years for LCD and PDP technologies. Early PDP TVs were released in the 1998-1999 timeframe, when the technology was already capably of sizes over 40 inches, twice the diagonal measure of the largest LCD panels at the time.