Choose between these two imaging technologies not always easy. Director Marcos Fernández, director of Christie for Spain and Portugal, brings in this detailed platform information to choose the best option for each application.
It is not easy to choose projector if we are not clear for what we need it. Reproduced in specification sheets, many projectors seem to us more or less equal. However, its operation and the quality of the image produced can make them completely different.
The rationale for these differences lies in the technology on which they are based, that can be (liquid crystal display) LCD, LCoS (liquid crystal on silicon) or DLP (digital light processing). In case outside little, own DLP has two varieties: a chip and three-chip.
Three-chip DLP is widely regarded as 'most of the more' in terms of image quality and screening standards. However, for applications that do not pursue the utmost in any aspect of concrete operating often enough with models DLP single chip or LCD technology. In this article we offer information to help you choose between the two technologies, whether with your application you are looking for the projection of data as if what you want is the viewing of videos, or both things.
The 'abc' of DLP
All DLP projectors are inside a chip DMD (digital micromirror device) covered with square mirrors of microscopic size, with a mirror for each pixel of the projected image.
All the mirrors rotate between two different angles: an angle that reflects the light from the projector lamp through the lens of the screen, creating a bright pixel; in doing so and another angle that reflects the light and away from the lenses to the an internal element that absorbs light, producing a dark pixel on the screen. To display an intermediate grey hue, all the mirrors rotate at high speed between both angles thousands of times per second.
Alone, the image that forms the DLP chip is seen in black and white. To produce images in color usually use two methods: a chip or three chips. The latter uses a DMD for each primary color (red, green, blue) that optically converge to produce a single image.
Single-chip approach is limited to use a DLP chip and is usually placed between the lamp and the DMD chip a disc that rotates at high speed and is called a color wheel.
The color wheel is divided into several areas, each of which contains a color filter. The minimum is one red, one blue and one green. Some projectors added a white segment to boost production of light, and others incorporated the yellow, cyan, or magenta.
Added in various combinations, three colors create a rich and colorful images. When you turn the wheel, each color lights, in quick succession, the DLP chip in a cycle that repeats several times per second. The image that is displayed on the DLP chip also complete cycles of information between the red, green and blue in sync with the wheel. Colors are your cycles at high enough speed so that the eye perceives the image to full color.
Some DLP projectors from a chip used, instead of lamp, Led (light emitting diodes) or a combination of Led and laser. Some of these models do not need color wheel to make colors cycle, performing this task electronically.
Principles of LCD
LCD projectors use a few small panels of liquid crystal, more that to reflect light, have been designed to transmit it. They generally use three panels, one for each color. Some projectors use a fourth panel to improve color reproduction.
Components of optical filters located on the inside of the projector divided white light from the lamp into the three colors (red, green and blue) then channelling them by their respective panels. The image is formed on a panel by altering an electrical signal (voltage) sent in quick succession to each pixel.
The result is the transmission of light through the LCD panel, creating on the screen a bright pixel; either the absorption of light by the panel, creating a dark pixel on the screen. Red, green and blue panels surround a Prism which ensures that all the resulting images are projected at the same place of the screen.
A chip vs. LCD: data or video content?
When choosing a projector for a particular application, it is important to ask ourselves what kind of content we will mainly show. Will it consist mostly of data for presentations, video playback, or a combination of both things?
Both the LCD and DLP chip projectors are suitable for both types of content. However, if our main need is the projection of data we would like to count with greater brightness which we can afford with a given budget. In that sense, a DLP projector of a chip designed for fixed installations will probably be the best option.
If, on the contrary, our needs are focused on video projection, colour reproduction must be impeccable, so the difference between a DLP projector of a chip and an appropriate LCD model will be minimal.
Today, and in a similar price range, there is not much difference in image quality or in brightness between a chip DLP projector and LCD projector. That said, here are a few distinctive characteristics that should know:
Color reproduction: all projector designs sacrifice shine for depth of projected colors, or otherwise. The option of an aspect goes inevitably to the detriment of the other. The result is that in some projectors colour is deep or accurate that in others, depending on what are its applications.
The typical commercial or business presentation may require brighter ambient lighting conditions; on the other hand, if what we need is to review data or brand standards, accuracy in color becomes priority, becoming also a prerequisite in video projection.
As a general rule, LCD projectors are placed in a medium term, showing acceptable colours in relation to the brightness project, while which are mainly intended for viewing of video sacrifice something light projection in the interests of a better chromaticism.
A chip DLP projectors cover one greater spectrum, ranging from models to presentations with colors simply appropriate to its function, to models with high quality colour designed for video. Some single chip DLP projectors offer the option of selecting playback settings optimum brightness or greater accuracy in color.
Color cycling speed in the case of a chip DLP, color cycling speed may vary according to the projector as well as, in some cases, depending on the settings of the software. Models to presentations the speed of colors tends to be slower than in the destined mainly to the viewing of video.
Therefore, some viewers perceive pictured a few fleeting multicolored traces (Rainbow) in the case of bright objects, especially when those objects are in motion. However, the perception of these devices varies depending on people.
Visibility of pixel: LCD projectors have greater distance between pixels that the DLP projectors, a circumstance which makes more visible the separation with the consequent reduction of the visual acuity of the image, something that, although it has much importance in a presentation It can be critical to watch a video. That is why images of DLP are considered more 'cinematic' the LCD images.
Lack of convergence: the lack of convergence is the term that refers an effect that can be that you've noticed in an LCD image: strips of color in horizontal and vertical lines. The effect occurs when the alignment that the images of the three LCD panels must be kept each other is not sufficiently accurate. And although the manufacturers make every effort to minimize it, the lack of convergence continues to affect some LCD projectors.
On the other hand, a chip DLP projectors have been designed with a unique creative chip image showing the three colors sequentially, by which a chip DLP projector will be free of the problem of the lack of convergence.
What happens with reliability?
Reliability is as important as performance, and the two technologies, LCD and DLP chip, work well in that aspect.
In the past, the projectors LCD panels could fail due to a progressive decomposition of ultraviolet (UV) light that seeps from the lamp.
A new technology that operates within the own LCD panel, called inorganic alignment layer, has meant an important step forward to increase the protection of the LCD against damage caused by ultraviolet light, yet, is solution continues without be the most appropriate in applications 24/7.
Image retention is a problem of the LCD. If an LCD projector or flat panel displays a static image for a prolonged period, the LCD tends to keep a post-Imagen effect, a kind of phantom image of the static image that remains visible with the new content already on-screen.
Most LCD manufacturers warn of the risk of this type of operation, a problem that can be especially serious in applications requiring operation (continued) 24/7, which enhances the chances of image retention. When required a 24/7 operation DLP projector option is much more advisable.
A chip DLP
In the case of the DLP, could think that a full mobile mirrors DMD chip is, of itself, unreliable by its mechanics and movement. However, while the mirrors are movable elements, they are so tiny that the forces involved in the movement are insignificant. Tests carried out over many years have shown that DLP chips are a great reliability and long life.
A key advantage of DLP technology is that, rather than internally absorb light in the imaging device to produce black, mirrors are limited to redirect the light to a 'absorber' inner light, which reduces thermal stress on the device (DMD) aum image I implementing considerably its life cycle.
Another traditional concern generated by the lamp-based chip DLP projectors is that is derived from the motor spinning the color wheel. It's an engine similar to the of the of the hard drives and that have proven to be highly reliable.
When it comes to reliability, another aspect to keep in mind is that a chip products sealed optics, which helps eliminate possible contamination of the panel which is often manifested in the screen in the form of dark spots or color distortion. On the other hand, it is not rare that LCD projectors require cleaning.
In conclusion, a chip projectors DLP and LCD projectors offer great value in a wide range of applications. In a given price range, products employing any technology tend to be similar in performance and results of operation.
However, there are fundamental differences between the two technologies, there are applications that, depending on the content - data or video, image quality and reliability – best fit one to the other. In this article, we have summarized the most relevant information to help you choose the best option for your application needs.
Director of Christie for Spain and Portugal
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