Projection Systems: Multimedia Presentations Come of Age
Elizabeth Greenfield · T.H.E. Journal Technological Horizons in Education · 1992
Projection systems extend the impact of a given presentation from one person to groups of people. They enhance small staff meetings or large lecture halls filled with students by enabling the audience to view text, graphics and animation, often in pseudo or true color. Participants are engaged and overall retention of the materials presented increased. Of the presentation devices available, different types of video/data projectors and panels are covered here. A definite trend is the continual modification of liquid crystal display (LCD) technology. From passive- to active-matrix, LCD is popping up in more and more places--whether replacing CRTs in video/data projectors or being integrated into light valve models. Participants are engaged and overall retention of the materials presented increased. Good news for those desiring to incorporate multimedia elements into their presentations: developers are now working to enhance LCD technology to better display motion video on panels in both real time and color. In fact, it is latest-breaking advancement. Through the use of many new technologies, some presented here, the multimedia picture is completed. That capability will become, in the near future, a de facto standard. * Evolution of the Panel For most small-scale presentations, LCD panels are virtually standard issue. Until recently, most panels displayed in monochrome--either black-on-white or white-on-black--offering several shades of grey. The next step was a twist on the shades-of-grey theory in which one color substituted for black and white. For example, many such panels offer eight shades of simulated color or 16 shades of magenta. Abundant and ever more affordable are true-color panels. Such models display 5,000 colors, 4,096 colors, 2,197 colors or 512 colors. Many passive-matrix monochrome and color panels can handle animation and simulations but not motion video. Educators who do not require motion video capabilities from a panel have many options from which to choose. For example, In Focus Systems manufacturers a standard, 16-color panel, the 1600LC, which projects at 640x480 resolution. This device is suited for educational applications since it supports Mac, DOS VGA and Apple IIGS platforms. Tucson Unified School District recently purchased 90 of the units to be used in its elementary, middle and secondary schools. Librarians in the elementary schools use the panels to teach groups of students how to use online reference materials; those in science and music classes are also benefitting. Just lately introduced and specifically relevant for multimedia presentations, thin film transistor (TFT) technology, or active matrix, supports the display of motion video by placing a transistor at every pixel location. These transistors apply voltage directly to the liquid crystal material at the pixel and holds that current until a signal makes it stop. However, not all TFT panels can inherently display motion video; some require that a video card be installed in the accompanying computer. All of the following models need such a card to handle video: * Dukane's latest foray into LCD panels, the MagniView Model 494, provides up to 117,000 true colors in 640 x 480 resolution. Offering a rear-projection capability, the unit also includes a remote control. The 494 is billed as the only LCD panel on the market that features a built-in memory drive, which displays up to 40 images and ten different sequences stored on one two-inch diskette. Dukane offers an accessory movie video interface adapter to allow the 494 to display video. * Chisholm offers the Rainbow Looking Glass, a TFT active-matrix LCD panel that offers 2,197 colors at 640 x 480 resolution. Included with the unit are VGA and Mac II video and monitor extension cables as well as a power supply. * Telex Communications, Inc. …