The single-chip DLP design has a unique advantage over all three-chip or three-panel systems: since there is only one imaging chip, convergence problems don't exist. There is simply nothing to go out of alignment. Contrast advantages. However, with the introduction of inorganic LCD panels that are now used in most LCD p home theater products, DLP's traditional advantage in contrast within the home theater market niche has been neutralized to a large extent.
No image persistence. If one displays a static image for an extended period of time, an LCD projector with organic LCD panels may have a tendency to retain a subtle ghost of that image even after the subject matter is switched to another image.
This does not occur on a DLP projector. Nor does it occur on LCD projectors that use inorganic panels. Some of the advertising hyperbole has blown the seriousness of this issue out of proportion. Burn-in, in traditional usage, refers to permanent damage that can be suffered by CRT or plasma phosphor-based displays. Once a static image has been etched into a phosphor display through long term exposure, it cannot be removed. This is a different phenomenon than we see on LCDs.
On organic LCD displays, when image persistence occurs, it is temporary and can normally be erased by displaying a white screen for a period of time. Nevertheless, the point is that image persistence does not occur on either DLP projectors or inorganic LCD projectors.
So on these products there is never any need to take steps to erase a persisting image. No degradation of image quality over time. There is usually no degradation of image quality on DLP projectors when used over long periods of time, other than that which might result from excessive internal dust build-up. But in any event, the DLP chips themselves will not degrade.
Conversely, LCD panels and polarizers can degrade with time, causing color shifts, unevenness of illumination, and reduction of contrast. The degree to which LCD degradation is a problem on current products is somewhat of a mystery since those who know the most about it the LCD manufacturers don't discuss it publicly.
This issue will be discussed further below. Pixels tend to have sharper definition on an LCD projector, and this can produce a more visible pixel structure in the image. This is often called the screendoor effect, since the picture on low resolution projectors can look like it is being viewed through a screendoor.
First, LCD makers have achieved smaller interpixel gaps, making the screendoor effect much less visible. Second, the average native resolution of projectors being sold today has increased dramatically over what it was several years ago. With increases in resolution come smaller pixels and a less noticeable pixelation across the board. Note: There is a disadvantage to having less distinct pixel structure, which is reduced image sharpness. We will discuss this further below. DLP leads in miniaturization.
The single-chip light engine affords the opportunity for extreme miniaturization that LCD cannot quite match. At the moment there are 15 DLP projectors on the market that weigh less than 3 lbs and put out more than lumens. By comparison, the lightest 3LCD projector on the market weighs 3.
Color wheels can produce rainbow artifacts. The problem people point to most frequently as a weakness in DLP is its tendency to produce "rainbow artifacts. They occur at random, and they only last for an instant. But for people who are sensitive to them, they can be quite distracting.
If you are engrossed in a film or video, they can take you entirely out of the video experience. Rainbow artifacts are a problem only on single-chip DLP products, and for the most part, only those using slower speed color wheels. Typically the problem manifests itself when the viewer is watching movies or video. When viewing static images such as presentation charts or photographs, people generally do not experience the problem. The rainbows occur because of the sequential color updating from the wheel or LED.
As the color wheel spins or the LEDs change, the image on the screen is either red, green, or blue at any given instant in time. The technology relies upon your eyes not being able to detect the changes from one to the other. However, when your eye moves rapidly in response to some movement in the picture, you can get a red, green, and blue update on three different points on your retina, thus producing the impression of a rainbow. Not everyone perceives rainbows the same way.
Many people have less sensitive eyes and cannot detect rainbow artifacts at all. Others see them quite readily. There is no way to know whether you are among those who can or cannot see them except by watching a DLP projector yourself.
Since LCD projectors and 3-chip DLP projectors always deliver a constant red, green, and blue image simultaneously, they do not create rainbow artifacts. On DLP projectors with color wheels, rainbow artifacts are reduced by increasing the speed of the wheel. With one red, green, and blue filter in the color wheel, updates on each color happened 60 times per second.
This rotation speed in the first generation products was known as a "1x" rotation speed. The doubling of the color refresh rate reduced the time between color updates, and so reduced the visibility of rainbow artifacts for most people. But a 2x rotation speed was still not fast enough for products to be used in home theater and video applications.
Today, some DLP projectors being built for the home theater market use a color wheel containing two sets of red, green, and blue filters. This wheel still spins at RPM, but because red, green, and blue are refreshed twice in every rotation rather than once, the industry refers to this as a 4x rotation speed. And by increasing the physical rotation speed beyond RPM, some projectors now have 5x or 6x speed wheels. For the large majority of users, the 5x and 6x speed wheels in most current home theater models have reduced rainbow artifacts in video display to the point where they are of little or no concern.
This is perfectly fine if the presentation matter is static charts, graphics, photography, or anything that does not stimulate rapid eye movement. We do not recommend DLP projectors with 2x speed wheels to buyers for whom video display or part time home theater are important intended uses.
Some DLP projectors have excellent color saturation, and some are exceptionally poor. This is related more to the vendor's implementation than anything inherent in the technology itself. Advocates of 3LCD technology have been quite vocal about the lack of color brightness on single-chip DLP products, particularly those that have white segments in the color wheel. This phenomenon is worth commenting on.
When a color wheel has a white clear segment, the lumen output of the projector is increased dramatically, and the ANSI lumen rating skyrockets. Most business class DLP products have white segments in the wheel to boost the all-important lumen rating. Conversely, most DLP projectors built for home theater have no white segments because they can compromise color saturation and the overall balance of the video image.
Moreover, the lumen rating is not a big driving factor in the sale of home theater projectors. When you use a light meter to measure the brightness of red, green, and blue on an LCD projector, the sum of the values usually adds up to the brightness reading you get for white. This makes sense because on an LCD projector, white is created by turning the red, green, and blue channels all fully on.
But on a DLP projector, this is often not the case. Due to the presence of a white segment in the wheel, the white reading can be as much as double the sum of the brightness readings for red, green, and blue. In other words, if an LCD projector measures lumens of white light, you will also get lumens of color light out of it. If a DLP projector measures lumens of white, you might get only lumens of actual color light from it, the rest being white light.
Because of this, proponents of 3LCD technology have been lobbying for color brightness specs to be included along with ANSI lumen specs on the industry's specification sheets, and support for this has been building in the industry. Not surprisingly, Epson and Sony have already begun to publish color brightness specs on their LCD projectors to drive home the point. The color spec is always the same as the ANSI lumen rating, and the specs will read, as an example, " lumens color light output, lumens white light output.
This is especially true when the color wheel contains the basic red, green, blue, and white filters only. Many DLP projectors have complementary color filters such as cyan, magenta, and yellow. In this situation the color brightness measurements become more problematic. Thus we can understand why Texas Instruments and the DLP projector vendors have little interest in publishing color brightness specifications.
From a practical perspective, we have mixed feelings about all of this. But neither does the color brightness spec.
Ironically, this can be particularly true when the "BrilliantColor" feature is enabled. Though BrilliantColor boosts the brightness of the image, it can substantially reduce color saturation in the process. It is peculiar that in order to get the richest and most saturated color from many DLP projectors, one needs to turn BrilliantColor off. This is not universally true of all DLP projectors with BrilliantColor, since the BrilliantColor system can behave quite differently based on how it is implemented by the vendor.
Oddly enough, on some DLP models with white segments in the wheel, even those on which color brightness falls far short of white, we see a rich, vibrant color that can easily match an LCD projector in the same price and lumen class. One reason is that the color filter configuration of the wheel has a lot to do with the end results.
Another reason is that, though the DLP's color brightness may fall short of white, the effect of the DLP's inherent contrast advantage helps to compensate for it. That compensating effect cannot be quantified in a spec. Even when color brightness falls very far short, the picture sometimes does not end up looking much dimmer at all when put side by side with an LCD projector of the same white light output.
When a DLP projector's color vibrancy looks poor next to a comparably priced and spec'd LCD projector, it is due to a variety of design and product cost decisions made by the vendor, and not anything inherent to DLP technology per se. DLP can look truly spectacular or downright dismal depending on what is done with it. With so many variables in play, the specs can't tell the whole story, even if a color brightness spec were added to the mix.
The publication of color brightness specs would be interesting, and would certainly draw attention to a noteworthy technical difference between LCD and DLP. But it is not conclusive information that would help an astute buyer sort out which model to buy. Dithering artifacts. At any moment in time, each mirror position on a DLP chip is either fully on to render maximum brightness, or fully off to render black.
Therefore, the way the DLP chip renders gray is to flip the mirrors on and off very rapidly, such that they are on just enough of the time for the eye to average the "on's and off's" to a desired level of perceived brightness.
This approach to rendering grays is called dithering. It works well enough for rendering gray values, but it can produce some visible instability in solid fields, mostly dark areas, referred to as dithering artifacts. Stock analysis. Market Research. ET NOW. Brand Solutions. Video series featuring innovators.
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The same image is created by the three LCD panels, but each with different hues due to the colored light through the panel. The images then combine in a prism, resulting in a single image with up to Finally, the image is passed through the lens for projection onto a screen.
DLP technology is 'reflective'. In a single-chip DLP projector, light from the lamp enters a reverse-fisheye, passes through a spinning color wheel, crosses underneath the main lens, and reflects off a front-surfaced mirror, where it is spread onto the DMD.
From there, light either enters the lens or is reflected off the top cover down into a light-sink to absorb unneeded light. In LCD projectors there are always three LCD panels, and they are always light transmissive devices rather than reflective or direct view displays.
Being light-source agnostic, DLP technology can effectively use a variety of light sources. Typically, the main DLP light source is a replaceable high-pressure xenon arc lamp unit.
For LCD projectors, Metal-halide lamps are used given their outputting an ideal color temperature and a broad spectrum of color. Smaller metal-halide lamps make LCD projectors smaller, hence more portable than most other projection systems. Here are two helpful shopping links for projectors on Amazon.
Liquid Crystal Display, known as LCD, works by putting a bulb inside the television which produces light. This light is then transferred to millions of crystals , in which an electric flow is used to change the colors on and off, assigning the right color onto the screen.
The colors are red, green or blue liquid crystals. One advantage of LCD is it conveys better color saturation. They are bright, crediting them as a better entertainment set than DLP.
They can be hung on the wall because of their size, which is less than 4 inches in depth, and less than 50 inches long.
Therefore, it allows viewing in a wide room, wherein some areas are not directly in front of the television. This is due to the crystals, and not with the light source, wherein the green color will fade, resulting in a red or blue tint. There is no other option but to change the TV set. Secondly, is the black level and contrast weakness, which are signi.
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