LCD PROJECTORS VS. DLP PROJECTORS - WHICH IS RIGHT FOR YOU?

When shopping for a digital projector, your first question might be: "Which type of projector technology is the best for me and what are the differences?"

Projectors come in two types - Liquid Crystal Display (LCD) projectors and Digital Light Processing (DLP) projectors -- referring to the mechanism the projector uses internally to compose images.


Both projection technologies have strengths and weaknesses, and it is important to know the differences so you can choose the technology that matches your needs. In this Aditiaudiovisuals.com article we will explain the technology behind LCD and DLP projectors allowing you to make an informed decision on the type of projector to purchase.

How does LCD technology work?

LCD projectors project light onto mirrors which split  it into three primary colours: red, green and blue. The colours then pass through three separate glass panels - called prisms - which is why this technology is referred to as 3LCD.

When light is projected through the LCD panels, individual pixels are opened or closed to allow light through or block it. The separate colours then converged using another prism and projected on to the screen.

What are the advantages of LCD Projectors?

1. More accurate colours
   LCD projectors do not have a colour wheel, which can reduce colour saturation.
   
2. Sharper imageLCD projectors have a slightly sharper image than DLP projectors at equal resolutions.
   
3. More light-efficient
   The same wattage lamp in an LCD and would produce a brighter image than in a simular DLP projector.

The disadvantages of LCD Projectors

The disadvantages of LCD are more relevant to video display than data applications.

1. Screen door effect
   The sharper image produced by LCD projectors can actually be a disadvantage, since the more precise focusing makes the pixilation ("chicken wiring" or "screen door effect") of an image more obvious.
   
2. Contrast
   LCD contrast may not be as good compared to DLP as LCDs cannot produce completely black images.
   This may not be an issue with newer, higher resolution 3LCD models.
   
3. Portability
   LCD projectors have more parts and so are bulkier and less portable than DLPs.
   
4. Image degradation
   With the addition of more parts,  LCD panels can experience long term image degradation where colour balance shifts and overall contrast is reduced.
   LCD panels can be expensive to replace.
   
   
5. Dead pixels
   Dead pixles can become a problem in LCD projectors, where one or more pixels turn permanently on or off.
   One pixel may not be noticible, but can become an annoyance if a cluster of pixels die.

How does DLP technology work?

Digital Light Processing or DLP is a proprietary system developed by Texas Instruments, and works differently than LCD projection. Most DLP projectors have a single chip instead of glass panels through which light is passed, and this chip has a reflective surface composed of thousands of tiny mirrors which correspond to individual pixels.

These mirrors move back and forth when beams of light hit the chip and direct the light from individual pixels either towards the projector lens or away from it. In order to define colours, DLP projectors have a colour wheel that consists of red, green and blue filters. The wheel spins between the light source and the DLP chip and alternates the colour of the light hitting the chip between red, green and blue. The mirrors tilt away from or into the lens path depending on how much of each color is required for each pixel at any given moment.

What are the advantages of DLP Projectors?

DLP projectors are a favourite amongst road warriors and home theatre enthusiasts for several reasons:

1. Portability
   DLP projectors tend to be smaller and easier to transport since they have one chip compared to the LCD''s 3 panels.
   
2. Higher Contrast
   The deep blacks achievable with DLP projectors make them very popular for home cinema applications.
   
3. Reduced Pixilation
   This is especially noticeable in comparisons of lower-end LCD and DLPs, and makes DLP a popular choice for smooth video applications.
   
4. Reliability
   DLPs tend to fail less often due to fewer parts and are less expensive to repair. DLP projectors have sealed optics, making them ideal for use in dusty environments.

The disadvantages of DLP Technology

1. The Rainbow effect
   You may experience a "rainbow" effect -- a momentary flash of rainbow-coloured stripes around brighter objects. This is typically only a problem in older DLP projectors without modern, faster 6-colour wheels.
   
2. Light leakage
   Some people may also experience "light leakage" from their DLP projector in the form of a grey band around the outside of the image.
   
   This is caused by stray light reflecting off the edges of the mirrors on the DLP chip. This can be avoided by installing black borders around the screen. Again, light leakage is generally only a problem in older DLP projectors.

Which technology is right for you?

The various advantages and disadvantages of LCD and DLP projectors mean each is suited for different applications. Lighter, less bulky DLP projectors are favored by presenters on the road and DLP projectors are also very popular with home theatre enthusiasts due to the higher colour saturation, better contrast and image stability. Entry level DLP home theater projectors are also very affordable.

LCD projectors are often more affordable then DLP projectors, making them attractive for education organizations. Their higher light output make them well suited for classrooms and larger conference facilities, as does their increased image sharpness. 

This makes them a good choice for displaying data-rich presentations such as spreadsheets and graphs.

LCD projection technology is currently leading DLP technology in market share due to the larger number of projectors using the LCD system. Sony and Epson are the largest LCD manufacturers, along with Hitachi and Sanyo. Optoma, InFocus and BenQ, on the other hand, use DLP technology.
The Future of LCD and DLP enhanced technology

Advances in LCD technology have been aimed at reducing the "screen door" problem and include:

• Higher resolutions
• Reductions in the gap between pixels
• The use of Micro-Lens Array (MLA) to boost the efficiency of light transmission through XGA-resolution LCD panels

The latest major DLP innovation is a projector system with 3DLP chips instead of the usual one. The three-chip DLP is similar to LCD technology in that the light is split up into red, green and blue by a prism and then each colour has a separate DLP chip off which the light is reflected. Three-chip DLP projectors are widely recognised as having the best looking images of all projector technologies, however they are also by far the most expensive.