Video projector

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A video projector or video projector is an optical device that receives a video signal and projects the corresponding image on a projection screen using a lens system, thus allowing to display still or moving images.

All video projectors use a very bright light to project the image, and the most modern ones can correct curves, blots and other inconsistencies through manual adjustments. Video projectors are mostly used in presentation or conference rooms, in teaching classrooms, although applications for home theater can also be found. The input video signal can come from different sources, such as a television tuner (terrestrial or satellite), a personal computer, and so on.

Another term similar to video projector is overhead projector which, unlike the first one, is implanted internally in the television set and projects the image towards the observer.

TRC projector **
Main article: TRC projector
The cathode ray tube (TRC) projector typically has three high performance cathode tubes, one red, one green and one blue, and the final image is obtained by superimposing the three images (additive synthesis) in analog mode.

Advantages: it is the oldest, but it is the most widespread in television sets.
Disadvantages: being the oldest, it is in extinction in favor of the other systems described in this point. TRC projectors are suitable only for fixed installations as they are very heavy and large, and also have the disadvantage of the electronic and mechanical complexity of color overlay.

LCD projector
The liquid crystal display system (LCD) is the simplest, therefore one of the most common and accessible for domestic use. In this technology, the light is divided into three and is passed through three liquid crystal panels, one for each fundamental color (red, green and blue); finally the images are recomposed in one, constituted by pixels, and are projected on the screen by means of an objective.

Advantages: it is more efficient than DLP systems (brighter images) and produces very saturated colors.
Disadvantages: a pixelation effect is visible (although the most recent advances in this technology have minimized it), the appearance of dead pixels is likely and the lamp life is approximately 2000 hours.
3D projector
Projector of last generation that shows images in a special screen treated so that the images that it projects surround the spectator giving the sensation of enveloping image.

Advantages: More inches with the projector, being able to see an image of for example 40 or 100 inches depending on the distance from the screen or area where we project.
Disadvantages: The lighting is slower than that of a television and the lamp life is shorter than that of a television panel. We will have to control the light in the room, in most cases leave it in the dark to enjoy better contrast and necessarily wear 3D glasses.
Overhead projector
A led picoprojector usually has 854 x 480 pixels and a brightness of 100 lumens and usually has a multicore processor.

Digital Projector
The digital projector is a device responsible for obtaining through a port, eminent video signals from the computer, processing the digital signal and decoding it so that it can be transmitted through light to micro mirrors that are responsible for digital projection.

History
Around 1880, Eadweard Muybridge invented the first projector (Zoopraxiscope), thus initiating movement and animation. Years later, it was the Lumière brothers who evolved this technology and created the first film projector.

Between 1940 and 1950, the invention of television and its arrival in homes, caused the projector to make a change in its technology, specifically, in the operation of CRT (Catadioptric Ray Tubes). In a CRT projector, the generated image is the same as in a common television. A color image (RGB model) is generated in analogue form using three red, green and blue tubes. These types of projectors were used until 1990.

In 2000, with the social situation and the desire to evolve, the first digital projection with DLP technology developed by Texas Instruments took place.

In this type of projectors with DLP operation, the image is created by means of micro mirrors, where each mirror represents a pixel of the image that will be projected. The number of mirrors will determine the resolution of the projected image. In this type of digital projectors, the contrast and depth suffer obvious improvements.

features
This type of projectors are characterized by having a great luminosity and brightness. This brightness is measured with Lumen, (the unit of measurement of the luminous flux). Another of its main features is the range, which is measured in inches. This is the maximum distance that can be displayed without losing quality or definition.

As for resolution, digital projectors offer a projection with a wide resolution, which is measured in pixels. This is the maximum number of pixels that the projector can display without losing image quality.

On the other hand, the consumption of digital projectors is measured in Watts, and is the energy that the projector needs for its operation.

This type of projectors, consist of a very high intensity lamp inside the barrel. This is responsible for determining the lifetime of the digital projector.

Preferably, the digital projectors must be placed in a fixed position. They are usually installed on ceilings or walls and it is for this reason that many work with remote control.