For a long time, projectors remained a specific office equipment for presentations and for showing slides during classes. The high price, low contrast and poor image quality discouraged the mass buyer.
But times have changed: in terms of price and image quality, projectors have approached TVs, but diagonals of tens of meters are unattainable for the latter
A 3D home theater with a wall-to-wall screen?
Bright and attractive advertising on any surface?
Quick design of any hall for any performance – from a rock concert to a scientific conference?
Projectors allow you to do all this and much more, you just need to understand their parameters and understand which of them are important in each particular case.
LCD. Projectors based on a single lumen LCD matrix are the most affordable of all available on the market. Unfortunately, such projectors can not boast of other advantages, except for the low price.
Image quality allows you to look at the screen only from a distance (near the picture it will “crumble” into colored spots).
The contrast of the image is low, because there is a large “empty space”between the pixels.
And since the manufacturer of a single-Matrix projector initially focuses on a low price, usually the resolution of the matrix is far from HD, and the lamp in the projector is inexpensive and dim. As a result, the brightness of the image allows you to fully use the projector only in complete darkness, and the low resolution “blurs” the image until the complete loss of small details.
For presentations in the office, for use in classrooms, such projectors are of little use. But as the basis of a home theater, they are quite suitable for not the most demanding viewer: the screen diagonal of more than two meters at the price of an inexpensive TV makes you close your eyes to the shortcomings of the picture.
3LCD. In projectors that use three clear LCD matrices, the image does not “crumble” into multi-colored pixels, even if you approach the screen. Thanks to this technology, the pixels on the screen are able to display any shades, and their useful area is much larger.
In 3LCD projectors, a separate monochrome LCD matrix is responsible for each color component. Rays of light pass through each of them separately, then they are combined into a whole using a prism.
3LCD projectors are characterized by good color reproduction and high-quality “images”. At the same time, their contrast is not as high as that of DLP projectors – even the highest quality LCD matrix can not provide complete non-transmission of light, and the “real” black color on a 3LCD Projector is not easy to achieve. In addition, liquid crystal matrices “do not like” high temperatures and require a constant puff of air to remove heat. This leads to the fact that a layer of dust gradually accumulates on the matrices, despite the presence of filters and their timely cleaning/replacement.
3LCD projectors are suitable for offices and educational institutions, as well as for home theaters. But when choosing a home theater projector, keep in mind that high-contrast 3LCD projectors are much more expensive than DLP projectors with similar characteristics.
DLP. In a DLP projector, the image is formed using a special DMD chip, on which there are many microscopic rotating mirrors that form a matrix of a certain size and resolution.
High resolution DMD chips contain millions of mirrors that are no larger than the thickness of a human hair. The light of the lamp falls on The Matrix, passing through the color wheel-a rotating transparent disk with sectors of different colors. When the projector works, the color components of the image are formed in turn, while the light beam passes through the corresponding sectors.
The control elements in the DMD chip are located behind the mirrors, and not around the pixels, as in LCD matrices, so DLP projectors have almost no gaps between the pixels.
Projectors using this technology are able to provide a “pure” black color: the micro-mirrors responsible for the Black color pixels reflect the light falling on them sideways, completely excluding it. The image generated by the DLP projector is characterized by sharpness and contrast.
The DMD chip is less susceptible to high temperatures, in addition, it has an effective heat sink on the back of the chip. The optical system of DLP projectors is located in a sealed case and does not require cleaning.
Recently, led-DLP projectors have become increasingly popular.
In them, color Rays are formed not when passing through the color wheel, but with the help of three powerful LEDs of different colors, which turn on in turn. Unfortunately, their brightness does not reach the brightness of gas discharge lamps, so the luminous flux of such projectors is small. But LED lamps are small in size and have a long service life.
The main disadvantage of DLP projectors is the”rainbow effect”. Because the color components of the image are projected in turn, at a high frame rate, they can refer to different frames. This is especially noticeable in dynamic scenes. The effect is manifested even if you simply change the direction of your gaze sharply-at different times, the eye captures different color components, which leads to the appearance of iridescent blurs on the edges of color transitions.
Manufacturers struggle with this effect in different ways: they increase the number of sectors in the color circle, increase the speed of its rotation, install 3 DMD chips – but all this leads to an increase in the cost of the projector.
Another disadvantage of DLP projectors is the difficulty with displaying shades of gray – in order for the eye to perceive subsequently changed pixels of different colors as a gray dot, the micro-mirror must turn especially accurately. On some DLP projectors, even on a static gray gradient, you can see colored stripes.
DLP projectors are also suitable for home theaters and presentations, although their strengths are more in demand when viewing movies, rather than charts and diagrams.
But when choosing a model for a home theater, first check how much you are hampered by the”rainbow effect” of DLP projectors. Because its influence is largely subjective-some people almost do not notice it, and some people are very annoyed about it.
LCoS technology (SRXD, D-IL, R3LCD) is designed to combine the advantages of both of the above technologies and eliminate their shortcomings.
In this technology, the image is formed by three monochrome LCD matrices (as in 3LCD), but not on the lumen, but with a reflection from their mirror substrate (as in DLP). Pixel control elements are located on the substrate, behind the pixels, and the useful area of the matrix is not reduced-the pixels are located close to each other. There is no “rainbow effect”, the picture is clear.
One drawback-while this is the most expensive technology-the LCOS projector will cost much more than both 3LCD and DLP projectors with similar features.
LCOS projectors, due to their high price, are currently available only in the professional segment and are used to create high-quality presentations, art installations, etc.
Pocket projector. The development of technology has led to the fact that the smallest projectors can really fit in your pocket – in size and weight, they are quite comparable to large smartphones.
Of course, their capabilities are more modest than those of full-size projectors: the low brightness of LED lamps and weak contrast do not allow them to be used in a bright room. But in the most total darkness, pocket projectors are able to create a fairly high-quality image with a diagonal of up to 40-60 inches.
The presence of a built-in battery and the ability to connect to a smartphone allow owners of such projectors to literally carry a cinema in their pocket and organize watching movies (or presentations) in any conditions.
However, the built-in battery lasts at best for 2 hours, so you need to look for an outlet. And the prices of ” children “are not” children ” at all – comparable full-size projectors will have many times better characteristics.
Portable projectors – all compact devices weighing 1.5-3 kg.
This type includes most projectors. They are quite mobile and easy to install and connect, often included with them is a carrying bag.
Projectors weighing 4 kg or more are designed primarily for fixed installation.
This class includes most professional installation projectors with high-brightness lamps, the ability to use in large halls and outdoors, etc.
The minimum and maximum diagonal projection dimensions determine the possible dimensions of the projected image.
The projection size corresponds to the projection distance: for example, the minimum projection distance, the diagonal of the image will be equal to the minimum diagonal projection size.
And the projection distance, in turn, corresponds to the focal length of the lens, which can vary in a limited range. Therefore, it will not be possible to get a clear image larger than the maximum (or less than the minimum).
Also consider the projection ratio (ratio of projection distance to projection width).
Thus, if the maximum projection size of the model is 100 “(220х120 cm) and the maximum projection distance is 5 m (projection ratio = 2.27), then to obtain a picture with a diagonal of 80″(180х100 cm), the projector should be placed in 180*2.27 = 4 meters from the screen. That is, in a 3-meter room the image of the maximum size is not obtained.
To get a large image at a short distance, there are ultrashort projectors-they have a minimum projection ratio.
Resolution is the number of pixels of which the image is composed in width and height. The higher the resolution, the sharper the image and the larger you can project it on a screen without any loss of quality. High resolution is important if the image needs to retain small details or readable text.
The resolution up to 800×600 is only suitable for viewing medium quality video (up to DVD). HD videos on this screen can also be watched, but the details will be lost.
For presentations containing small graphics, diagrams and text, a resolution of 1024×768 is recommended.
To watch HD movies without loss of quality, the resolution must be adequate-1920×1080. To watch video on large screens (7-10 meters diagonally or more) and the highest quality when playing 4K content, a resolution of 3840×2160 is recommended.
Aspect ratio. For office projectors and in educational institutions, it is better to choose projectors with a ratio of 4:3: presentations, documents and slides on such presentations is more convenient. And for the home theater, the best ratio will be 16:9 or 16: 10..
The luminous flux affects the brightness of the image. The higher the luminous flux, the higher the brightness of the projector.
A luminous flux of up to 400 Lm is only suitable for showing relatively small (60-80″) images in complete darkness. The luminous flux of this level is typical for portable projectors.
The luminous flux of 400-1000 LM is suitable for the organization of entry-level home theater. With these values, you can create a sufficiently bright image up to 100 ” in an unlit room in the evening.
A luminous flux of 1000-1800 lm makes it possible to distinguish information on the screen in partial light conditions.
Projectors with a luminous flux of more than 3,000 lumens are suitable for work in large well-lit rooms or outdoors.
The contrast of the projector is determined by the ratio of the brightness of black to that of white. Contrast is responsible for the depth of black (the so-called “pure black”), for the saturation of “images”, for the display of low-contrast elements.
For office projectors, this setting is not very important: in presentations and demonstration slides the images themselves are contrasting; halftones and color transitions do not occur often. Yes, and the” pure “black color in a lit office or public is not necessary to talk-the most “black” color on the screen will still be determined not by the characteristics of the projector, and the lighting of the room.
But for the home theater, the contrast ratio is important-a picture with a weak contrast will look faded and unexpressed.
Among cheap projectors, DLP technology offers better contrast. Projectors have a higher contrast ratio between DLP and 3LCD.
Which contrast to choose? The question is complicated, since there are several methods for measuring contrast, and which one was applied specifically by the manufacturer – it is not always possible to understand. The presence of a diaphragm on the projector allows the manufacturer to specify a dynamic contrast higher than the native one (with an unchanged aperture) hundreds of times. So dear projector with contrast plate of 2000: 1, can give much deeper and richer “image” than the market in declared contrast of 10,000:1.
When choosing a projector, be sure to pay attention to the life of the lamp: its price is sometimes close to the price of the projector itself. Lamps with a resource of 2000 hours when watching movies a day will be enough for a year or two of work, after which expensive repairs will be required.
If you want the projector to be able to be used independently, without a set-top box and a computer, pay attention to the presence of a TV tuner and playback from USB drives.
Just keep in mind, these options sometimes (especially on low-cost models) are implemented by the manufacturer on the residual principle. The reception quality of the TV tuner can be quite poor, the built-in media player can ignore some audio and video formats, and the USB connector can “hit” and refuse to read any hard drive.
3D support: this option is required for almost half of projectors, and many buyers (similar to 3D TVs) expect these projectors to show a polarized stereo pair. Alas, make at home IMAX 3D based on the projector c “3D support” will not work.
Most projectors with “3D support” only mean the ability to display an anaglific image. If you view an image through anaglyph (red-blue), glasses really a certain effect, but bad color rendering really impression.
Some projectors can work with stereo shutter-here the effect will be better, but these projectors are much more expensive, and glasses need to be purchased separately.
Projectors that display polarized stereo pairs exist, but they are very expensive and need special screens that do not violate polarization.