LCD PROJECTOR TECHNOLOGY
When choosing a new projector, one of the first decisions will often be whether to buy an projector which uses Liquid Crystal Display (LCD) technology or a projector which uses the Digital Light Processing (DLP) projector technology. It can be a difficult decision for a number of reasons. Most obviously because both types of technology essential perform the same function - projecting an image on to a screen.
Often people will favour one technology over another because they are familiar with the manufacture or have used the product before. For those who have no experience, knowing the strengths and weaknesses of both LCD projectors and DLP projectors can be important to make sure the right kind of projector technology is chosen for the task at hand.
This Projector Source Canada article will focus on Liquid Crystal Display (LCD) projector technology, to give you a good idea of the applications where LCD will be the most appropriate choice of projector to invest in. To do this, we will describe how LCD projectors function to display an image and then discuss the advantages and disadvantages of LCD projector technology.
What is LCD technology?
LCD, which stands for Liquid Crystal Display, is currently the most popular type of projector technology available on the market to consumers, having gained a greater market share than the competing Digital Light Processing (DLP) technology developed by Texas Instruments. This was originally because LCD projectors were cheaper to manufacture and so were more affordable for consumers, although at the expense of a reduction in the quality of the projected image.
Recent technological advancements in projectors have seen both increases in the quality of LCD projector images and decreases in the price of DLP projector technology. Both technologies are now able to offer sharp, vibrant images at lower costs than in the past, but LCD projectors are still generally wider spread than DLP projectors.
To produce an image, LCD projectors use a number of liquid crystal panels through which light is passed, unlike in DLP projectors where a Digital Micromirror Device is used. How an LCD projector works will be covered in a separate section below.
What is 3 LCD technology?
The "3" in 3LCD refers to the number of LCD panels, or chips, used inside a 3LCD projector. When using three LCD panels each primary colour has a dedicated chip, where as one-chip projectors use a rotating colour wheel to sequentially display colours. The main advantage that 3LCD offers is that there is no "rainbow effect" which is a problem some users can experience where they perceive a separation of the colours which produces a rainbow like shadow on fast moving images, causing an irritating distraction. 3LCD projectors are often the choice of projectors for movie theatres since they can display up to 68.7 billion colours.
Technical specifications of liquid crystal display technology
When buying an LCD projector it is important to be aware of what the technical specifications listed on projector feature sheets refer to. Here are the most important elements to be aware of:
The LCD projector''s contrast ratio:
The higher the figure for an LCD projector''s contrast ratio, the brighter the image that will be projected on to the screen.
The LCD projector''s throw distance:
A projector''s throw distance is the length that the image can be projected -- basically the maximum distance between the projector''s lens and the projection screen.
The number and type of inputs:
The type and number of devices that can be connected up to the projector will be determined by the incoming connection ports on the projector. It is important to compare the connectors that your input device uses with the connectors on the projector to make sure you get the best image possible.
The number of pixels the LCD projector can display:
An LCD projector''s pixel count will determine the resolution of the image that will be displayed. Usually, the higher the resolution, the better the quality of the projected image.
The LCD projector''s lens:
The qualities of the projector''s lens is a very important feature. Remember to check the abilities of the lens. Lens shift and zoom capabilities allow the image to displayed clearly from variable distances. Short throw lenses will mean that the projector can render a large image on to a projection screen from very small distances, whereas a long throw projector lens is one which can produce a small image from much further away from the screen.
The LCD projector''s aspect ratio:
A projector''s aspect ratio affects the dimensions of the image that is projected on to the screen. A widescreen 16:9 aspect ratio is preferable for projecting films since they also use a 16:9 aspect ratio. Many laptops know also use this specification.
How does an LCD projector produce an image?
Inside an LCD projector there are three glass LCD panels that are dedicated to each of the primary colours (red, blue, and green). When light enters the projector from the projector''s lamp, two mirrors are used to divide the light into these three colours before sending them to their specific panels.
Thousands of tiny pixels compose these panels. After being electrically charged these pixels are used to allow variable amounts of light to pass through them to compose the final image. Using a prism the three colours from the LCD panels are recompiled before projecting the final image on to the screen.
What are the advantages of LCD projectors?
The reasons for the popularity of LCD projectors can be attributed to several advantages:
Energy efficiency has recently become an important factor for consumers and businesses alike when buying electronic devices. LCD projectors are typically more efficient with the light that the projector''s lamp produces i.e. an LCD projector will produce a brighter image than a DLP projector when using a lamp with the same wattage rating.
Better brightness levels
Images appear to have a greater saturation when projected using LCD technology, meaning that although a corresponding DLP projector might have a higher contrast ratio, the same projection on an LCD projector may appear brighter.
No rainbow effect
In terms of disruptions to image quality, LCD projectors are not affected by screen burn-in, picture processing noise, or "the rainbow effect" which is often seen in single chip DLP projectors using a colour wheel.
What are the disadvantages of LCD projectors?
Like any other device that uses LCD technology, dead pixels can become a problem in LCD projectors. A dead pixel refers to a pixel that has stopped functioning and is either permanently on or off, which causes a black, white or coloured dot to constantly appear on the screen. While these are generally unnoticeable in isolated situations, when they appear in clusters they can be highly distracting.
Reductions in portability
Since LCD projectors are composed of more parts than DLP projectors, their housings tend to be bulkier which has the side effect of making them less portable. This can be an important consideration for those presenting on the move, although LCD projector technology, like most electrical technology, is getting smaller all the time.
Long-term image degradation can become a problem if an LCD projector is frequently used over a long period of time. The internal machinery of an LCD projector is composed of many more individual parts than DLP projectors. This consequence of this is that the internal components of LCD projectors are more likely to fail and when replacing them they are more expensive to replace than DLP parts.
As LCD projectors heat up faster than DLP projectors, LCD projector fans tend to be much louder when operating than their DLP equivalents.
"Chicken wire" effect
A problem known as the ''chicken wire'' effect can occasionally occur in LCD projectors, especially older models. This is when the grid type pixel pattern of the LCD''s panels can become noticeable on screen, causing the image to appear pixelated.
When would you want to use LCD technology?
As the technology in LCD projectors is far cheaper to produce and is also highly versatile, LCD projectors can be adapted for many different purposes. Hence why they are currently the leading projector type in the projector market.
The cheaper price of LCD projectors makes them preferable when operating under a limited budget or buying many projectors in bulk. For these reasons, schools and universities frequently use LCD projectors. High-end LCD models with high contrast ratios are also available which are suitable for use in home theatres.
The higher light output of LCD projectors means that they are a good choice for classrooms and larger conference facilities. LCD projectors also benefit from increased image sharpness which makes LCD a great choice of projector technology for displaying data-rich presentations such as Excel spreadsheets and detailed graphs.
Which manufacturers produce LCD projectors?
As LCD projectors currently hold 65% of the projector market penetration and are cheaper to produce, they are slightly more popular amongst manufacturers of projectors. While DLP is a proprietary technology owned by Texas Instruments, LCD is a technology that is free to be altered and improved upon by any manufacturer. In fact, Sony and Epson both produce their own type of LCD technology. This allows for projectors to be produced that are tailored to specific user applications such as a home theatre.
We hope you enjoyed this article by Projector Source Canada. For more information, or to purchase a display and projector for your business or home, visit us online at http://www.projectorsourcecanada.ca
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