Presentation Equipment

Many people use laptop systems to host presentations to audiences that can range in size from the boardroom to an auditorium. For all but the smallest groups of viewers , some means of enlarging the computer display is necessary. Most portable systems are equipped with a standard VGA jack that allows the connection of an external monitor.

Notebooks typically enable the user to choose whether the computer's screen image should be sent to the notebook's internal LCD screen, to an external monitor, or to both. Users can toggle among these options, usually by hitting a certain keystroke combination or by adjusting the system BIOS. Depending on the capabilities of the video display adapter in the computer, you might be able to use a greater display resolution on an external monitor than available on the internal LCD panel. However, if you want to display simultaneously on both an internal and external screen, you will obtain the best results if both displays have the same resolution. For example, if your laptop screen has XGA resolution (1024x768) and you are using an external monitor with SVGA resolution (800x600), you should set your laptop screen to SVGA resolution if you want to get good results on both screens simultaneously .

For environments in which the display size of a standard external monitor is not large enough, several alternatives exist, including LCD panels for use with overhead projectors, digital projectors, and large plasma displays.

See "Liquid Crystal Displays (LCDs)," p.491 (Chapter 11)

Analog TV Projectors

For many years the only way to project a computer screen was to use an analog TV projector. These were large suitcase-size devices. On the front panel of these devices are three large projection lenses, one each for red, green, and blue light. These projectors were usually bolted either to the ceiling or to an audiovisual cart.

Because of their large size, high price tags, and low resolution, analog TV projectors have been replaced by newer technologies.

Overhead LCD Display Panels

An LCD display panel is similar to the LCD screen in your computer, except that there is no back on it, making the display transparent. To use this panel, you have to place it over a standard overhead projector, which projects the image onto a large screen. The display technologies and screen resolution options are the same as those for the LCD displays in portable systems. In recent years, many users have abandoned LCD display panels in favor of self-contained digital projectors. Because of this, most vendors of overhead LCD display panels have discontinued these products, although many AV houses might still have them available for rental.

Digital Projectors

Most people who want to display an image for a large group of people now use a digital projector. These units are typically small but project bright images with high contrast. They do an excellent job, not only with computer images, but also with video signals from a VCR or a DVD player. Best of all, the prices for these devices continually drop. We have already seen prices drop below $1,000 and should continue to see further decreases. Just 5 years ago, the typical price was over $5,000.

Basically, a digital projector is a self-contained unit that is in effect a combination of a transparent display panel and a projector. The unit connects to the VGA video output connector on the system, just like a regular monitor, and frequently includes speakers that connect with a separate cable. Not all LCD projectors are portable; some are intended for permanent installations. The portable models vary in weight, display technologies, and the brightness of the lamp, which is measured in ANSI lumens. Typical portable projectors have ANSI lumen outputs ranging from 500 to 3,000 or higher, with prices ranging from well under $2,000 to well over $10,000. Less expensive projectors are typically SVGA (800x600) resolution, whereas more expensive models are typically XGA (1,024x768) or higher resolution.

Digital projectors can display images at several resolutions. All but one of these resolutions are made possible by averaging or interpolating pixels in order to enable the native resolution of the projector to simulate other resolutions. To display an image with the best clarity, always use the native resolution of the projector. All other resolutions that the projector claims to support will appear slightly blurry by comparison.

For best results, match the resolution of your projector to the native resolution of your notebook computer. For example, if your notebook computer has an XGA (1,024x768) resolution screen, make sure your projector has this same native resolution. Having the projector and your notebook's built-in screen match resolutions usually enables you to take advantage of simultaneous display ”a great benefit for presenters.

Internally, digital projectors use one of two different techniques to form an image: an array of three LCD panels or a DLP mirror chip.

LCD Projectors

The oldest and least expensive technology used in digital projectors is LCD technology. The LCD approach is said to provide better color fidelity, but it often gives an image a window-screen look ”as if the image is being seen through a typical window screen.

In this technology, a beam of light from a bright lamp is separated into three beams, each of which pass through a separate tiny LCD screen typically less than an inch in size. Most recent LCD projectors use 0.7-inch LCDs. The three LCD screens correspond to the red, green, and blue components of the image. The three resulting images are then combined and projected out to a screen.

One of the most popular examples of an LCD projector is the Toshiba TLP-S30U (see Figure 14.21). Its use of LCD technology and its relatively low native resolution of 800x600 has enabled it to be one of the most affordable projectors on the market. With a weight of 4.8 pounds , it is also one of the lightest LCD projectors available.

Figure 14.21. The Toshiba TLP-S30U, a popular LCD projector.

DLP Projectors

DLP projectors use DLP, or Digital Light Processing , chips from Texas Instruments. Projectors using this technology tend to be smaller but more expensive than LCD projectors. Typically, images from DLP projectors do not have the window-screen look that is characteristic of LCD projectors. The latest DLP projectors also offer extremely good contrast, which is important for entertainment applications such as displaying movies.

In DLP projectors, a bright beam of light is projected on a tiny array of thousands of microscopic mirrors. Each pixel of an image is controlled by a single mirror. Color is usually provided by a rotating wheel of color filters.

The compact nature of DLP projector technology has been put to good use lately in some very lightweight models. These projectors, such as the InFocus LP-120, weigh just slightly more than 2 pounds and are not much larger than a Tom Clancy paperback book.

Flat-Panel Plasma Displays

These amazing displays are becoming more and more common in corporate boardrooms ”and even some living rooms. The main factor is their stunning appearance. These displays are often extremely large ”usually 42 inches in diagonal or larger ”and extremely thin. They look more like picture frames than televisions . A DVD movie or High Definition TV picture viewed on one of these screens is stunning.

A plasma screen consists of hundreds of thousands of tiny gas-filled cells. In effect, the cells are like microscopic fluorescent bulbs . When a current is applied to the cells, the electrons free themselves from the atoms of gas and form a plasma, which glows . Similar to a color television, the cells are located behind a matrix of tiny red, green, and blue filters. Almost any color can be obtained by applying the right combination of these three primary colors.

Most plasma displays can readily connect to the VGA connector on a laptop for use as a high-quality presentation tool. Note, however, that some of the low-cost plasma screens (that is, below $5,000) do not offer very high resolutions ”often below 800x600. Many plasma displays feature unusual resolutions (for example, 852x480 and 1024x1024) that may not be supported directly by a laptop's graphics adapters.

TV Connections

One of the simplest display solutions is a feature that is being incorporated into many of the high-end laptop systems on the market today. It enables you to connect the computer to a standard television set. Called TV-Out , it usually consists of an RCA jack that can supply a composite video television signal. In addition to providing support for the North American NTSC television standard, a few notebooks also support the European PAL standard. If your portable computer doesn't have a TV-Out connector, PC Cards and add-on adapter boxes are available to provide this feature. These products convert the VGA signal to a form that is compatible with the NTSC or PAL TV standards.

Obviously, an integrated TV-Out connector is an extremely convenient solution because it provides an image size that is limited only by the type of television available, costs virtually nothing, and adds no extra weight to the presenter's load when a TV is available. However, the display resolution of a television set does not approach that of a computer monitor, and the picture quality suffers as a result. It is recommended that you test the output carefully with various size television screens before using TV-Out in a presentation environment. To obtain the best results in presentations, use simple sans-serif fonts, such as Arial and Helvetica, in relatively large sizes. Also, limit the amount of text on any given screen to achieve best results with TV-Out devices.

S-Video

Some notebooks have an S-Video connector. This enables your notebook to display a higher resolution image than would otherwise be possible with the standard TV-Out connector.

In some notebooks from Dell, the S-Video connector does double duty. In addition to connecting with a standard S-Video cable, it can also connect to a standard composite video cable with the help of a short adapter.

Digital Video Interface (DVI)

In time, the traditional RGB or VGA connector on notebooks and desktops will be replaced by a DVI (Digital Video Interface) connector. Unlike the older VGA connector, which was analog, the DVI connector can supply a true digital link that will be less subject to noise from other nearby electronic devices.

Currently DVI connectors can be found only on certain high-end video components. These include desktop video adapters, digital projectors, large plasma displays, and certain high-priced LCD displays. A few PC Card adapters are available to provide notebooks with this capability when needed for use with high-end displays.

Perhaps the easiest way to equip a laptop with a DVI connector is to insert a Display-to-Go PC Card from Margi (www.margi.com). In addition to a standard analog (VGA) connector, Display-to-Go can interface with both Digital Flat Panel (DFP) and DVI connectors.

Another advantage of a video card such as this is that it supports the multiple-monitor capability of recent versions of Windows. This card works as a secondary graphics adapter, enabling Windows to spread its images over two displays. Users are thus able to run separate applications on their notebook LCD and their external secondary display. A typical scenario is that of presenters launching their presentations and dragging them to the secondary display devices for their audience to see. At the same time, they could launch their notes on the laptop screens, which would be visible only to them.

TV-In

A small number of notebooks are equipped not only with a TV-Out connector but also with a TV-In port. With the right software, these notebooks can record or capture images from a TV or video camera. For notebooks without this feature, an optional PC Card can provide a TV-In connector.

The TV-In feature of laptops uses an RCA jack and accepts standard composite video signals. In order to handle the higher quality images available from today's digital mini-DV camcorders, you should use an IEEE 1394 (or FireWire) interface. In addition to passing video signals from the camcorder to the laptop (and back), the IEEE 1394 interface also enables digital video-editing software on the laptop to control the camcorder in order to facilitate the transfer of images.

Outside of Sony and Apple, very few notebook vendors are currently equipping their systems with IEEE 1394 interfaces. In most cases, you will have to use a special interface card, described next .