pctechguide.com

  • Home
  • Guides
  • Tutorials
  • Articles
  • Reviews
  • Glossary
  • Contact

LCD Projectors

Since the LCD panels of a projector are too small to apply a colour filter by vapour deposition in the same manner as notebook monitors, the light must first of all be split into the three primary colours of red, green and blue.

This task is performed by so-called dichroic (double-refracting) mirrors. These are produced by coating glass with metallic oxides inside a vacuum furnace. Different metallic oxides reflect only a specific part of the light spectrum, while allowing all other light components to pass through. Two dichroic mirrors arranged in series thus split white light into red, green and blue light.

LCD panels are used to block differing amounts of each colour, allowing a total of 16.7 million colours to be produced when the light paths are recombined in a dichroic cube. The recombined light is the launched via the projection lens onto the screen.

LCD

The introduction of polysilicon has made it possible to miniaturise the transistor elements in a projector’s LCD panels, enabling both higher light transmission and a reduction in the size. On the 0.9 inch panels of modern XGA projectors, for example, 786,432 pixels are located on the surface area of only 2.5 square centimetres. Since a projector three LCD panels, one for each of the primary colours, it possesses more than 2.36 million pixels which can be activated individually to guarantee absolutely precise rendition down to the smallest detail.

In order to clearly separate the individual pixels, LCD projectors employ a microfine grid to prevent the light from one pixel influencing the adjoining pixel. The light is thus partially absorbed before making impact with the liquid crystal layer, in order to prevent cross-fading. This means that although the grid has a positive effect on picture quality it also entails some loss of light.

High-end projectors compensate for this light loss by incorporating a micro lens array (MLA) in front of the microfine grid. Each of these tiny lenses concentrates the incoming light and directs the entire quantity of light exactly through the matrix, so as to ensure that the minimum possible quantity of light falls on and is absorbed by the grid itself.

As well as increasing luminous efficiency from between 50% to 70%, micro lens technology also minimises a type of pixelisation that afflicts LCD projectors. When a projector’s lens is sharply focused each individual pixel can appear on the screen as though in its own little black box. The lines of the boxes are where the control electronics stops the light from shining through the panel. It’s somewhat like looking at the scenery through a fly screen, and is thus referred to as the screen door effect.

Contrast levels on LCD projectors are determined by how efficient they are at blocking off light. This has to be done by each of the three LCD panels. The result is an image that has dark grey blacks rather than black blacks. This problem is of more relevance to video than to data applications.

Other issues with LCD projectors are:

  • Their susceptibility to heat; the organic compounds used in LCD filters – in particular the blue – can be broken down by excess heat, resulting in a degradation of image quality.
  • Dead Pixels; pixels can become permanently on or permanently off, and while this is barely noticeable with one dead pixel, the presence of multiple dead pixels can be a irritation.

On the plus side, LCD projectors are the elder statesmen of digital projection; they’ve been around for longer than rival technologies. The actual LCD panels are made by several companies – including Sony and Epson – and these are then incorporated into many different manufacturers’ designs. A consequence is wide availability and – especially for mid-level projectors – competitive prices.

Historically, LCD projectors delivered better colour saturation than the rival DLP technology. The principal reason for this was the inclusion of a clear segment in the colour wheel of early single-chip DLP projectors. While this had the effect of making the image is brighter than it would otherwise be, it also tended to reduce colour saturation. The advent of six-segment colour wheels in DLP projectors has significantly reduced LCD technology’s advantage in this area.

Another advantage of LCD is its superior light-efficiency. For a given lamp wattage, an LCD projector will generally have a higher ANSI lumens rating than a DLP projector. This enables LCD technology to compete extremely well in situations where high light output is required.

When the first portable LCD projectors appeared in 1993, they used high-temperature polysilicon (HTPS) VGA LCD panels and a small, high-brightness metal-halide lamp. By 2004 the first crop of projectors capable of 2K (1920 x 1080) resolution were coming to market and lumen ratings had reached 3000 and more.

No matter what display resolution is available, customers will always want more pixels on the screen. While research and development efforts will continue, it appears that we may be close to reaching the performance limit for transmissive LCD technology. The trend away from transmissive imaging technologies looks to be firmly established, and tomorrow’s higher-resolution projectors are likely to be based on reflective imaging technologies such as DLP and LCOS.

  • CRT Projectors
  • LCD Projectors
  • DLP Projectors
  • LCOS Projectors

Filed Under: Projectors

Latest Articles

Can Alexa Help Your Business To Become A Top Player On The Web?

Alexa Internet Inc. was founded in 1996 by Brewster Kahle and Bruce  Gilliat as an independent company and acquired by Amazon.com in 1999. Now simply recognized as Alexa, this now belongs to the web analytics service industry. Alexa acknowledges that it can provide subscribers commercial web traffic … [Read More...]

4 Top Challenges of Using Business Card Software

The graphic design industry is growing at a remarkable pace. According to research from IBIS World, the industry generated $14 billion in revenue last year. The rising costs of visual creative professionals have encouraged many people to try using design software themselves. Unfortunately, this is a … [Read More...]

SCSI Internal Configuration

Before mounting the device, you'll need to configure it via the jumper switch located on the rear of the drive. SCSI ID setting: The three leftmost jumpers are used to configure the drive's SCSI ID number. This can be assigned a value of 0 through 7. Usually, 7 is reserved for the … [Read More...]

Revolutionize Your Internet Experience with Orbi 960 – The Ultimate WiFi System

In a world where seamless connectivity is essential, slow and unreliable internet connections are a major problem. Whether you are running a business, … [Read More...]

Do You Need a VPN When Trading Cryptocurrency?

There’s no doubt that the biggest global industries in 2023 are tech-driven, while there remains a significant crossover between many of these … [Read More...]

Goodbye Bitcoin: the 3 alternative cryptocurrencies that have great upside potential, according to experts

Bitcoin has been a very lucrative investment for people that got into it early. One report from The Motley Fool pointed out that $10 of bitcoin … [Read More...]

Self-driving cars face their Achilles’ heel and may be targets of hackers

The market for self-driving cars is booming. Customers spent $22.22 billion on these autonomous vehicles in 2021 and they will likely spend more in … [Read More...]

How to avoid scams with bitcoin and other cryptocurrencies

Cryptocurrencies got a bad reputation when scams multiplied like ants on a piece of cake. Even today many people associate bitcoin and other … [Read More...]

WHAT IS CLOUD COMPUTING AND WHAT ARE ITS MAIN BENEFITS?

Users are Increasingly using cloud computing to store their information, which is replacing local storage. The business digitization process goes … [Read More...]

Guides

  • Computer Communications
  • Mobile Computing
  • PC Components
  • PC Data Storage
  • PC Input-Output
  • PC Multimedia
  • Processors (CPUs)

Recent Posts

CRT Monitor Resolution and Refresh Rates (VSF)

The most important aspect of a monitor is that it should give a stable display at the chosen resolution and colour palette. A screen that shimmers … [Read More...]

DVD Encoding

DVD-Video can be encoded to either MPEG-1 or MPEG-2, as summarised in the table below: MPEG-2 MPEG-1 PAL/ SECAM resolutions 720 x … [Read More...]

Direct3D

The key to the way Direct3D (D3D) allows the game developer to author games independently of PC's hardware is its … [Read More...]

[footer_backtotop]

Copyright © 2023 About | Privacy | Contact Information | Wrtie For Us | Disclaimer | Copyright License | Authors