Choosing a LCD Projector Manufacturer
Unlike older overhead projectors, modern digital models use metal-halide lamps with an excellent color spectrum. They deliver 2,000 to 15,000 American National Standards Institute (ANSI) lumens.
LCoS projectors are generally pricier than LCD and 1-chip DLP, but they offer superior inherent blacks and contrast. JVC and Sony each offer a range of models, including native 4K ones.
Technology
LCD (Liquid Crystal Display) technology has been around for a while – it’s used in TV screens and computer monitors, and you’ve probably seen it in handheld devices like smartphones. But when it was first used in a projector in the 1980s, it revolutionized big-screen presentations and entertainment by offering high resolution, bright images that are more life-like than older projection technologies.
These devices work by passing a metal-halide lamp’s light through a combination prism or spinning color wheel that separates the light into the red, green and blue components of a video signal. The polarizers and the LCD panels allow only a specific part of the light to pass through, and as a result, each pixel can be opened or closed to display different colors.
The three imagers – one for each color – are then combined by the light engine and projected onto the screen using a lens. The pixel structure can be visible at close range, particularly on 720p or lower resolutions, and this is sometimes referred to as the “screen door effect.” Some companies, such as Panasonic, use an optical element they call smooth screen in their LCD projectors to modify the pixels to reduce this visibility.
Many modern LCD projectors use Digital Micromirror Device (DMD) imagers with a native resolution of up to full digital cinema 4K (4096×2160). Some home-theater models lcd projector manufacturer feature 1080p DMDs, which are able to simulate UHD by shifting the pixels back and forth diagonally a fraction of a pixel 120 times per frame using an oscillating optical refracting plate called an e-shift algorithm.
Design
The first commercial LCD projectors were bulky and expensive. Even the state-of-the-art at InfoComm Projection Shoot-Out back in 1994, with VGA (640×480) resolution and all-analog inputs, could crank out only about 500 lumens with relatively poor uniformity and had a retail price of $8,000.
The most popular projectors are based on 3-chip DLP technology, which has a large share of both business and education models as well as the pico category of compact, portable devices. These use three projector chips instead of one to achieve higher brightness ratings and more stable color.
Most LED projectors use metal-halide lamps for their light sources, which produce a broad spectrum of colors and high white light output. They’re also a lot less expensive to operate than most traditional projectors, consuming about half as much electricity.
Other projection technologies also exist, including outdoor projection tv the liquid crystal on silicon (LCOS) displays used in some premium home-theater projectors. These are a little more expensive than the typical LCD projector, but they provide superior picture quality and offer a much wider range of features.
Most LCD projectors with 1080p imagers simulate UHD (4K) resolution by using a technique called pixel-shifting. In this approach, an optical refracting plate oscillates back and forth to shift the final image diagonally by about a half-pixel for each frame. This greatly increases the number of pixels and reduces the “screen-door” effect visible on a standard home-theater screen.
Performance
LCD projectors have traditionally offered rich color saturation and image sharpness. At my first InfoComm projection shoot-out in 1994, a state-of-the-art LCD projector from a top brand was available for $8,000. It had VGA (640×480) resolution and all-analog inputs, could crank out about 500 lumens, with poor uniformity, weighed 25lb. to 30lb. and cost between $8,000 and $10,000.
Today’s LCD projectors use the same technology that is used in televisions and computer monitors. The tiny control transistors that make up each LCD pixel are manufactured on large wafers using amorphous silicon or low-temperature polysilicon processes. These chips are then cut to size and bonded together for each projector imager. In addition to delivering high-resolution imaging, modern LCD projectors also offer advanced features such as wireless connectivity and interactive capabilities.
Like DLP projectors, most LCD projectors employ three DMDs, one for red, green and blue. However, there are less-expensive models that use just one DMD. These single-chip units typically produce twice as many color lumens as competing DLPs, producing vivid individual colors that blend in our brains to create a full-color image. LCoS (liquid crystal on silicon) projectors are another option. General Electric demonstrated its first low-resolution LCD projectors in the 1970s, and JVC introduced the world’s first 1080p home-theater model based on LCoS technology, called SXRD, in 1998.
Maintenance
Projectors require powerful lamps that must be shielded from dust, durable power systems, complex circuitry for filtering inherent electrical interference, a system of air and, at times, liquid cooling as well. The components are highly sensitive and can be irreparably damaged if not handled properly. This makes the maintenance procedures a major part of their overall operation.
The most common problem with projectors is dust contamination. This can manifest as a tinted image or specks on the screen. These spots are caused by dust on the polarized plates of an LCD or on the color modules in a DLP projector. Neither type of projector is completely immune to the problem, but both can be reduced by following a regular maintenance cycle.
Dust can also clog intake and exhaust vents, causing overheating. Clean the filters as often as your user manual instructs and avoid using your projector in areas with dusty conditions.
Never move a projector while the lamp is on or when it is hot. Be sure to turn off the projector, unplug it from the outlet and let it cool down before attempting to remove it. When disconnected from the outlet, use a soft, dry cloth to remove any excess grease or oil. Be very careful when handling the plug and avoid touching it with your bare hands.