The high cost of projectors is explained by their complex design: it is necessary to place millions of control elements on a couple of inches of matrix area, while ensuring that it can work in powerful lighting conditions. The answer to the question: “How to choose a projector?” depends primarily on its purpose. The requirements for an office model for presentations and for a home theater projector are very different. For example, if you need a portable device for road presentations, then compactness and brightness come first. If you are creating a home theater – image quality and quiet operation. To understand the advantages and disadvantages of different models, let’s first understand how modern projectors work.
The image is obtained by passing light through a liquid crystal matrix. This approach allows the production of portable portable models with good brightness characteristics. Among the disadvantages are the inevitable noise from the fan cooling the matrix (liquid crystals are very sensitive to overheating), image pixelization (the image is covered with a grid of matrix pixels), and the fact that liquid crystals have some inertia, familiar to many from LCD monitors and TVs. The higher the resolution of the matrix, the thinner the grid from the borders between pixels and the greater the range of resolutions that the projector can work with.
Often, several matrices are used to increase the brightness and image quality – this is how the most advanced liquid crystal projectors are arranged.
Projector Screens are among the most popular on the market. And the spread of cost depending on the model allows you to choose a projector of this type both in the office and for home use.
The heart of such a projector is a reflective matrix, consisting of a huge number of micromirrors. The light from the lamp is passed through a rotating light filter and, reflected from the matrix, hits the screen. Due to the fact that the matrix does not work through transmission, like a liquid crystal, the light flux hits the screen without loss, which gives a gain in brightness. Another advantage compared to LCD is that the boundaries between the mirrors are smaller than between the elements of the liquid crystal matrix, so the pixel grid is less noticeable. Well, the third plus is the lack of inertia. There are also disadvantages – the image is formed discretely (the point is either lit or not), while liquid crystals allow you to get different gradations of illumination.
There are several approaches to improve technology. The first is an increase in the number of matrices. The second is an increase in the number of filters. Most often, a transparent filter is added to the standard three colors – this allows you to increase the brightness of light areas (note that this approach is not entirely fair and often leads to a deterioration in color reproduction).
I would like to warn the reader against buying inexpensive DLP projectors for watching video. They often have a noticeable flickering effect, which leads to fatigue during prolonged viewing.
DLP projectors, along with LCD, occupy the most massive niche on the market.
This technology has taken the best from LCD and DLP. A complex matrix based on liquid crystals does not work for transmission, but for reflection, while the D-ILA matrix is able to operate in a much tougher temperature regime than LCD and has thinner boundaries between elements than DLP (the grids are almost invisible). Many experts consider this technology to be the most promising. Unfortunately, today D-ILA projectors are rather exotic, considering their exorbitant cost.
The image is formed using three kinescopes for each of the colors, the image from which is combined on the screen using three lenses. It is clear that portability cannot be expected from such a solution, and such projectors are very difficult to set up and require the help of a specialist. But the image quality is worth the effort! Faithful reproduction of colors and the finest shades and the absence of pixelation, no noise during operation – all this makes these models a good choice for an uncompromising home theater. In this case, you can see through your fingers that the device weighs a good 70 kilograms and provides a low level of brightness (this is not a problem in a dark room).
CRT technology is no longer used in the production of modern models, and those that can still be bought are very expensive.
Each of the technologies has its pros and cons. We hope that after studying them, you will have an idea of what the “pitfalls” of a particular model can be. Usually you have to choose between LCD and DLP models.
Some projector options
Lamp resource is a very important parameter, because a lamp can cost several hundred dollars. Typically, the manufacturer indicates this number in the main parameters of the projector (from tens to several thousand hours of operation, depending on the model). The lifespan can be extended by using a lower brightness viewing mode. You should also make it a rule: do not keep the projector on all the time. You should not turn on the projector in advance and should immediately turn it off after viewing (even having a screensaver turned on will not really help, because the lamp always shines with the same brightness!).
If you make a mistake in the brightness down, then the light in the room may be at the level of the light output of the projector. The result is almost nothing to see. The larger the image size, the higher the projector’s brightness requirements.
Let us give approximate estimates of brightness for different purposes.
- Brightness 800-1500 ANSI lumens can work only in partial dimming conditions, the approximate audience size is up to one hundred people.
- If you increase the brightness bar to 1500-2500 ANSI lumens, then the projector is able to function in bright light in an audience of up to 150 people.
- If you are the lucky owner of a model with a brightness of 2500 ANSI lumens or more, the image size can be very large, and the audience can reach 250 people.
Of course, these are only rough estimates, more accurate data can be obtained only by knowing the specific conditions of use.
It is characterized by the ratio of illumination of the brightest (white) to the darkest (black) part of the image. The higher the contrast, the better the finest shades of light are transmitted. In the case of DLP projectors with a bright part of the filter, the contrast may be slightly higher than the real one (because the white brightness is too high). Such a projector will remarkably “work out” schemes on a white background (showing a real contrast ratio of 2000: 1), but when showing a video, a bright sector will not help much
In order to get an image of the desired size, the projector must be at a certain distance from the screen. The shortest distance is for projectors with short throw lenses, the largest for those with long throw lenses.
The more of them, the better. You may come across the following options: HDMI, D-Sub or RGB for connecting to a computer as a monitor, DVI for connecting camcorders (mostly), S-Video and composite RCA are standard video inputs for DVD players. Also, modern projectors are equipped with a USB port and a card reader.
Correction of geometric distortions
The main distortion that you have to deal with is the trapezoid. Due to the fact that the projector is usually located below the screen, the picture takes not a rectangular, but a trapezoidal shape. This problem is usually solved by the projector’s processor, which recalculates the image accordingly so that it looks rectangular on the screen. But from the point of view of quality, a much better option is when the correction can be carried out optically, without loss of information (which is almost impossible to avoid when recalculating).
The screen is an indispensable accessory for the owner of the projector. One should not think that a whitewashed wall will successfully replace it. Modern screens are made of materials that are unique in their optical properties and can significantly improve image quality.
Ceiling and wall mounts help save space in your presentation room. With this mount, you will have to control the projector using a remote control , which can be purchased separately. It is very convenient if the remote control can also be used as a laser pointer (however, it can also be purchased separately).
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