Index of Questions

A.  An ANSI lumen is the measure used to record the amount of brightness a projection device projects.  (as standardized by the American National Standards Institute)  An ANSI lumen is not a measure of "lumens" expressed in non-ANSI terms (and used to measure, for example, the output of overhead projectors). 

Q. How many ANSI lumens do I need to get a good image?

A.  Appropriate ANSI lumen rating depends on room lighting and screen size.  As a general rule of thumb, a rating of 400 to 600 ANSI lumens is adequate with a 60" diagonal screen with room lights off, but you should look for something in the 700 - 1000 range for a 100" to 150" screen with dim lighting, and at least 1300 ANSI lumens when you go to a 300" screen or want to project in bright lighting conditions.  The best way to be sure, of course, is to ask your EverTech Sales Representative to demonstrate several projectors under conditions typical to those you work under. 

Q. What is Digital Light Processing (DLP)?

A.  Digital Light Processing Technology from Texas Instruments:  Digital Light Processing (DLP) technology enables a projector to digitally control light as it creates images. Hundreds of thousands of digital light-switch micromirrors reflect beams of light to create and project an entire picture. These mirrors turn on or off hundreds of times per second to enhance detailed images. DLP picture elements ensure straight lines and sharp edges.

DLP projection technology displays every pixel evenly from one corner of the screen to the other. The distance between pixels is so minute (1/100 the thickness of a human hair) that images are projected with no observable lines between pixels. This means images are clear and crisp.  No more ragged and/or pixelated edges.

The DLP engine also uses a special lamp designed to provide the most uniform image possible. All of these elements combine to provide photo-realistic picture quality that is visually astounding. 

Q. What are DTV and HDTV?

A.  DTV, Digital Television, is a new broadcast standard that provides sound and picture quality far higher than the current NTSC broadcast standard in the US.  With DTV, viewers can view images up to six times the resolution of current television. HDTV, High Definition Television, is one of the formats that may be transmitted when DTV becomes available. HDTV broadcasts are the high end of the DTV broadcast. These broadcasts will have the best sound and picture quality  and the ability to broadcast in a wide screen format. 

Q. What is a Firewire?

A.  A Firewire is the new connection proposed for use with digital video devices, and which has already begun to show up on some digital camcorders.  Firewire consists of six total wires: two are for power, two for data, and two for synchronization. 

Q. What is keystone correction?

A.  Keystoning is when a projected image appears wider at the top or bottom due the projector's positioning somewhere offcenter from the screen.  The image usually appears in a trapazoid-like shape.  "Keystone correction", or "lens shift", corrects this distortion.  Most LCD projectors have a fixed keystone factor (allowing the projector's placement to be about an 8-degree angle higher or lower than the center of the screen).  Many new projectors allow you to adjust keystoning.  Adjustable keystoning allows you to place the projector on a desk, on carts or tables of various heights, or mount it on a ceiling of any heights with no image distortion. 

Q. What is an LCD panel?

A.  LCD stands for Liquid Crystal Display.  An LCD panel is a translucent (you can't see through it but light will pass through it) glass panel that shows a data or video image using a matrix of tiny liquid crystal displays, each creating one pixel ("picture element," or dot) that makes up the image.  In the past, these panels were often used with an overhead projector for a light source to create a reasonably effective computer projection device.  Nowadays, it almost always refers to the smaller (sometimes as small as a 1" diagonal!) panels used internally in the LCD data/video projectors of today. 

Q. What is an LCD projector?

A.  A self-contained unit that combines one or more LCD panels and a light source for use as a data and/or video projection device.  Much more convenient and efficient than using a separate LCD panel and overhead projector, LCD projectors come in a wide variety of size and capacity. 

Q. What is monitor loopthrough?

A.  An output on a projector or large-screen monitor that allows you to connect additional projectors or monitors to display the same image.

A loopthrough output is most commonly used to run a desktop computer monitor and its projected image--thus allowing you to sit or stand at the computer and always face your audience.  Another way to display the image in more than one place is with the use of a simple Y-cable.  It is wise to confirm compatibility with your projector before purchasing a Y-cable.  Use of the wrong Y-cable with computer signals can damage your equipment.  The Y-cable allows you to split the signal between your monitor/laptop and your projector(s).  A laptop's internal circuitry must split the signal between the laptop's monitor and the external device.  Although most laptops have such circuitry; some do not. 

Q. What is peak lamp life?

A.  Most LCD projectors use a metal halide source, which proffers a very white light and a life of 750 - 2,000 hours or more at no less than 50% initial brightness. They typically do not burn out, but rather, they gradually grow dimmer.  The dimming becomes obvious over time, giving you plenty of warning when the time for a replacement arrives.  With this type of lamp, total lamp life is not an especially useful measurement, as the lamp will continue to function long after they've dimmed beyond efficient usage levels.  Most manufacturers offer a peak rating.  Peak lamp life is the time the lamp will last at 75 - 90% of total brightness. 

Q. What is pixel mapping?

A.  Pixel mapping, otherwise known as "intelligent compression,"  "AccuBlend™," and "Fit-to- View^®,"  along with a variety of other names, uses a computer algorithm to map high resolution computer images to a lower resolution LCD.  Pixel mapping returns a much higher quality than "compression."  In the past, compression has returned a poorer quality image.  Now, with new digital compressing, the image retains almost all of its original quality.  Both the pixel mapping and the compressing algorithms work best when stepping down only one resolution setting.

Using an 800 x 600 projector you can get very good pixel-mapped 1024 x 768 images.   Going to 1280 x 1024, the image will be complete, but it may be blurry. 

Q. My Projector is 10 feet from the screen, how to I calculate the image dimensions?

A.  Once the throw ratio is determined (see above), we can calculate the diagonal distance of the image. For example, the DP5600 throw ratio is 1.9 (maximum) to 1.2 (minimum). Using the formula diagonal = distance / throw ratio, the diagonal can be calculated from which the width and height can be calculated. (NOTE: For the following calculation, only the dimensions for a maximum screen size of 10 feet have been calculated. Minimum screen size can be figured by using the DP5900's minimum ratio of 1.2.)

Calculate the maximum diagonal:

Once the diagonal has been calculated, the width and height can be calculated.  Use the following formulas:

width (horizontal) = diagonal x 4/5

height (vertical) = diagonal x 3/5

Calculate the maximum screen size:

Thus, at 10 feet from the screen, the maximum projected image will have the following dimensions:

Maximum zoom:
throw ratio = 1.9, diagonal = 5.3 feet, width = 4.2 feet, height = 3.2 feet
 

Q. What is resolution?

A.  The resolution of your computer display measures the amount of detail that can be seen in an image, expressed as the number of distinct horizontal and vertical lines visible on a test pattern. 

Q.What is horizontal and vertical resolution?

A.  A video or computer image is made up of rows of horizontal and vertical pixels. Its resolution is limited by the number of distinguishable rows, or lines, that the monitor or LCD device can form. "Horizontal resolution" or, more properly, "horizontal lines" is the number of distinct lines that you can count going across the image--but if you look at your monitor, these lines would actually go up and down, or vertically. "Vertical resolution" measures the number of distinguishable lines you can count from top to bottom in the image.

In computer projection, the number of lines is only limited by the signal coming out of the computer and the quality of the projection device. In television, the number of vertical lines of resolution is fixed: the American, or NTSC, standard is 525 vertical lines. The number of horizontal lines will vary with the quality of the monitor or projector used, but is still limited to less than 400 by NTSC standards. This limit is one of the barriers that will be broken by the introduction of Digital Television late in 1998. 

Q. What is a scan converter?

A.  A scan converter is a device that you connect between your computer and a regular television or monitor to allow them to display computer signals. The idea sounds good, but in reality when you convert a computer signal this way it becomes very difficult, or impossible, to read text, although pictures will look satisfactory. The reason for this becomes obvious if you refer to the above articles on VGA and Horizontal and Vertical resolution. Even the best televisions or non-data monitors are designed to NTSC standards which gives you a maximum resolution of 400 x 525. VGA computer signals are 640 x 480 and the higher resolution SVGA or XGA are fast becoming the standard making the problem even worse. No matter what you do, you can’t clearly display 640, or more, lines of information on a monitor only capable of 400. So, unless you are planning to display nothing but pictures, or very large text, a scan converter probably won’t do what you hope it will. 

Q. What is Throw Ratio?

A.  Throw ratio is the ratio between the projector's distance from the screen (throw distance) and the diagonal of the projected image. This number can be fixed or defined in a range if the projector has a zoom lens. 

To determine throw ratio, divide the projection distance by its respective image size diagonal.  If there is a range of image size diagonals, then the throw ratio will also be a range.  The Impression A10 (listed below) when projected at a distance of 4', has a minimum image diagonal of 1.9' and a maximum of 2.6'.

	4 1.9 = 2.1	(max throw)
	4 2.6 = 1.5	(min throw)

Below is list of throw ratios for some Proxima projectors:

Q.What is VGA?

A.  VGA, (the acronym for Video Graphics Array) measure the resolution of the video signal being output by a personal computer.  VGA, SVGA, XGA, and SXGA are all standardized "levels" of this measurement. The VGA "level" consists of 640 vertical lines x 480 horizontal lines, S-VGA, 800 lines x 600 lines, XGA, 1024 x 768, and S-XGA, 1280 x 1024.  The higher the resolution, the sharper, crisper and more detailed the image.  A higher resolution will also allow more to fit on your screen as it makes everything proportionally smaller. 

Q. What is a video line doubler?

A.  A video line doubler (or scan doubler) increases the number of lines of vertical resolution from 525 to 1,050 lines. Though it starts with a fixed, 525-line signal, the device uses a mathmatical algorithm to create 525 more lines in between the lines coming from the signal. The result is a much sharper image. 

Q. What is a wireless mouse control?

A.  A device that simulates the operation of your computer's mouse from a wireless remote control, generally the same control that operates your projector's other functions. 

Q. Why would I want a wireless mouse with my projector?

A.  A wireless mouse enables you to walk away from your computer during presentations.  Even if you find it difficult to precisely control the mouse pointer, you'll find it invaluable when using presentation software such as Powerpoint^® or Astound^®. Just having the ability to click the mouse buttons to advance or reverse the slides in a presentation make it a “must have” item for presenters.