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There has been so much written by the computer press regarding active matrix color displays that STN color ( Super Twisted Nematic; also referred to as passive matrix) screens have been somewhat overshadowed. The reality is that for many users STN technology (especially the newer dual scan screens) also offers high quality color with the added advantages of being more affordable and more available than active matrix displays.
The choice between which color technology to purchase should be based on several factors including a user's application, budget, and desired delivery time. The purpose of this paper is to provide insight as to which technology will best suit a user based on the factors mention above.
Choosing A Display To Match Your Application
Both STN and active matrix display technologies offer outstanding color that will please even the most demanding notebook users. Although active matrix technology does provide some advantages and is a necessity for a few applications, many users will find STN color perfectly suited for their requirements. When is dual scan STN color a great choice for your application? When is owning a notebook with an active matrix display a necessity versus an expensive luxury? In order to answer these questions, it is necessary to understand the strengths of each technology and how these strengths apply to the user's application.
Dual Scan STN: Exceptional Color At An Affordable Price
With the advent of dual scan technology, STN displays have made quantum leaps forward in the areas of color quality, response time, and overall desirability. Those users whose only memory of STN (passive) technology is the older, washed out displays will be stunned by the vibrant colors, higher contrast, and quicker response times of the newer dual scan screens. With this dramatic improvement, STN displays now offer outstanding color capabilities at extremely affordable prices. Users can expect to be able to purchase STN color notebooks at street prices that are up to $600 less than active matrix models. STN is also the easiest of the color displays to produce and thus is more readily available in all dimensions including the larger 9.5" size. Since they are easier to build, STN color displays can be expected to ship in much larger quantities than other technologies for the foreseeable future. In addition, STN provides the advantage of providing better viewing than other color technologies in bright, sunlit conditions (quantifiable as perhaps 10% better to the naked eye).
Users will find that dual scan STN color displays are now extremely well suited for almost all of their applications including Windows-based software, as well as all word processing, spreadsheet, and data base packages. In addition, much of the proprietary software that
has been developed for sales force automation and data collection use very basic primary colors.
In this case, purchasing active matrix technology is an expensive luxury and STN color will truly provide the best, most economical solution. Until recently, the video controllers used for STN color displays did not support 256 colors at 640 x 480 resolution. This made notebooks with the active matrix screens and their superior video controllers a requirement for high quality photo scans. However, Toshiba's new T4700CS supports 256 colors on the notebook's screen and has thus taken the next step in making STN color displays successful, more cost effective alternatives to active matrix.
Active Matrix: The Ultimate Color Display
Although active matrix technology is priced significantly higher than other displays, it does offer some important advantages when compared to other technologies. First, active matrix displays exhibit considerably faster response speeds than other screens. Secondly, displays using active matrix technology offer significantly wider viewing angles than STN color screens. On a lesser scale, active matrix displays also offer advantages in terms of contrast and color saturation. Knowing that an active matrix display's primary advantages are its super fast response time and wide viewing angle makes it easy to identify the applications where it will excel. Since full motion video and sophisticated animation depend heavily on fast response times to eliminate blurring, active matrix displays are considered essential for displaying these applications in the best possible manner. Also, its wider viewing angle almost makes active matrix a must when the notebook will be used for presenting to groups of 3 or more that will be gathering around the computer. Of course, if a presentation is being given using an external display device (i.e. external monitor, In Focus overhead panel...), then a notebook with either an STN or active matrix display will provide the same results as long as the video out capabilities are similar. On the negative side, active matrix displays are difficult to produce, resulting in far less availability and significantly higher prices than STN screens. The higher price delta will be a fact of life throughout time, while the constrained availability situation is expected to last at least through the end of 1994.
Summary
Both of the display technologies discussed in this paper provide outstanding color capabilities. Users that rely heavily on full motion video and sophisticated animation in their applications will more than likely require an active matrix display. Likewise, users who will be presenting to groups of more than three people gathered around their notebook should look almost immediately to active matrix. For all other applications, however, users should start their evaluations by examining the STN color models and owe it to themselves to evaluate this solution before they move on to the more expensive active matrix technology. Users should also understand that, in general, STN color is lower in cost and more readily available than active matrix. With this full understanding of the technologies and other surrounding issues, users will be ensured of buying the color technology that truly fits their needs, their time frame for delivery, and their budgets.
Notes On Toshiba's Newest Color Notebooks
T4700C Series: The T4700C series provides Toshiba's most powerful notebook computers and boasts the following features: 50MHz i486DX2 processor, two PCMCIA slots, 200MB or 320MB hard disk drives, and a choice of a 9.5" STN (T4700CS) or 9.5" active matrix (T4700CT) display. Both models enjoy enhanced video performance provided by local-bus video and a graphics accelerator. The T4700CS is Toshiba's first dual scan color model to support 256 colors at 640 x 480 resolution meaning that this cost effective notebook provides the most striking dual scan STN display to date. The T4700CT will ship in December and is expected to experience constrained availability for the foreseeable future. The T4700CS will start shipping in large quantities in January 1994 and is being offered at a street price that is approximately $600 less than the T4700CT.
T1950CS and T1950CT: The T1950 series provides the power of a 40MHz i486DX2 processor in a notebook computer affordable to even the most price conscious user. Key features include a 14.5mm PCMCIA slot, choice of 120MB, 200MB, or 320MB hard disk drives, 4MB of RAM standard, and the new BallPoint mouse 2.0 with Quickport. The T1950CS offers a large 9.5" dual scan display with 16 colors at 640 x 480 resolution; the T1950CT offers an 8.5" active matrix screen that supports 256 colors at 640 x 480 resolution. The T1950CS will have an approximate $400 street price advantage versus the T1950CT. While both models are in full production, the T1950CS is expected to available in much larger quantities for the near term.
"Dual scan screens deliver richer colors with less smearing than the single-scan passive-matrix screens."
PC Computing January 1994
"As long as manufacturing yields on active matrix screens remain low, prices will remain high. For the frugal buyer, dual-scan passive-matrix technology -- in which the top and the bottom halves of the screen are refreshed independently at twice the normal refresh rate -- provides an excellent alternative to the high end."
PC Computing January 1994
"The biggest decision you'll make about a color notebook is whether to go with active or passive displays; the greatest determinant in your decision will be price."
PC Magazine December 21, 1993
"Why is your next notebook going to have a color display? Prices on passive-matrix color notebooks continue to plummet because the screens are relatively easy to produce. Manufacturing yields on active-matrix displays remain low, however. Their prices have coasted along and are expected to stay where they are through the end of 1994."
PC Computing January 1994
"...if you're doing basic chores like word processing or spreadsheet work, you'd do well to save yourself some money and go with a passive unit."
Computer Shopper May 1993
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Toshiba America Information Systems Inc. (" TAIS ") shall not be liable for damages of any kind for use of this information, Which is subject to change without notice. Copyright 1994, 1995 TAIS.