How a projector works. Which projector to choose for home theater. Optical design of a two-matrix DLP projector

The image on which is displayed on a transmissive (for projection TVs) or reflective (for projectors) screen, the size limit of which for projection TVs is about 110 inches, and up to several meters for projectors.

According to the principle of operation, among video projectors and projection TVs, the following types are distinguished: on picture tubes (CRT), on LCD (LCD) matrices, on LCD matrices on a silicon substrate (LCOS) and with a micromirror device (.

Projection TVs and projectors on LCD (LCD) matrices have 3 main matrices

Micro-mirror projection TVs are more commonly referred to as DLP. At the heart of DLP technology is an optical semiconductor, a digital micromirror device, or DMD, which was invented in 1987 by Larry Hornbeck of Texas Instruments. A DMD crystal is a high-precision matrix that digitally converts light, in other words, a high-speed microcircuit, the surface of which consists of many microscopic mirrors that reflect light. A beam is formed using millions of microscopic mirrors. Each such mirror corresponds to one pixel in the projected image. When a digital video or graphic signal enters the DLP system, a microscopic electrode located under each DMD mirror is activated, causing the mirror to tilt either towards the light source or in the opposite direction. When the mirror is tilted towards a light source, it reflects one pixel of light through the projection lens onto the screen. When tilted in the opposite direction, light does not hit the mirror and the corresponding pixel space remains dark. Each DMD mirror is capable of tilting thousands of times per second. By varying the length of time the light hits the mirror, you can achieve the display of different shades of gray. If the mirror is tilted towards the light for longer than in the opposite direction, it displays a light gray pixel, and when the tilt time from the source is longer, it displays a dark gray pixel. Thus, DMD mirrors can display up to 1,024 shades of gray for ultra-precise black and white images. The last stage of digital light processing is converting the resulting monochrome image into color. Most DLP systems add color by using a light filter called a "color wheel" that is placed between the light source and the DMD mirror panel. As the color wheel rotates, red, green, and blue light consistently fall on the DMD micromirrors. By coordinating the angle of each mirror with these flashes of light, a standard DLP system can reproduce over 16 million different colors.

LCD TVs on a silicon substrate are arranged as follows. The LCD is located on top of a single mirrored substrate. Light from the lamp hits the mirror surface through the LCD matrix. Thus, a ready-made "picture" is reflected on the screen. Various methods are used to effectively add color to a black and white image. The technology was originally based on a single-chip principle. Light was added by high-frequency time division - a red, green or blue picture was alternately projected onto the screen (as a competing option - the color wheel in DLP TVs). Today, three-chip technology is used - like a regular LCD, LCOS uses a separate matrix for each of the three colors. This allows you to display colors much more accurately and realistically.

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See what "Video Projector" is in other dictionaries:

112. Video projector E. Video projector F. Projecteur vidéo A device for displaying color or black and white television images using optical projection onto a screen

Choosing a home theater projector, buyers are well aware that they need the best multimedia device, but they do not always understand the intricacies of its characteristics. Now, many models of the world's leading firms are represented on the domestic market of the Russian Federation: Sony, Epson, Optoma, BenQ and others, so choosing a decent projector, and not an analogue of the Chinese assembly, is not so easy.

Home theater projectors appeared on the domestic market recently, but immediately gained popularity among the wealthy part of buyers. Over time, the production of these products increased, budget models appeared, which are gladly acquired by representatives of different strata of society. Like any other technique, projectors have their advantages and are not without disadvantages.

Advantages:

• good ratio of the screen diagonal and the cost of the projector;
• the set takes up much less space than a TV with a similar diagonal.

Disadvantages:

• preparation of the premises is necessary;
• the screen is purchased separately, if with a remote control (remote device), then at the price of a budget projector;
• noise impact from the cooling system;
• periodic lamp replacement is required if the projector is not category LED.

Types of projectors

How to choose a home theater projector and at the same time get a really reliable and high-quality device? Experts say that you can watch movies on any kind of such devices, it all depends on your personal preference. Among the models intended for demonstration of cinema at home, there are three main ones:

1. Entertainment centers " all in one bottle», Which includes the projector itself, a player, an acoustic system. Such devices have the main advantage of being easy to install and operate. It is enough to connect the device to the mains, match with the position of the screen, and you can enjoy viewing. The main disadvantage is the weak characteristics of the built-in speaker system.
2. The entry-level cinema product is a home theater projector equipped with matrix with a resolution of up to 1280x720 (800). Manufacturers refer to them as entertainment models: Epson EH-TW450, BenQ W1070. These products have a good ratio of image quality to cost, therefore experts recommend their purchase to the general population.
3. The high class of projection devices for the home is Full HD with a matrix resolution of 1080 pixels (1920 x 1080). This type includes Sony VPL-VW350ES, BenQ W3000 and others. These multimedia products provide projection of any format of information that comes from different sources: camcorder, PC, TV tuner, game console.

Projectors are also classified according to the way the light passes from the lamp into . The advantages of the former include a very high contrast and an even distribution of the color gamut over the entire screen area, while the latter have no rainbow effect and high efficiency with less power consumption.

Key parameters

When buying, it is necessary, in addition to the cost, to pay attention to the following parameters:

1. Light flow should be in the range of 1000-2000 lm. Such an image is clearly visible in a lighted room, and there is no need to observe a partial or complete shading mode.
2. Contrast limit - from 1000: 1 to 2000: 1. If this figure is lower, then the dark scenes in the film will be almost indistinguishable.
3. Noise level cooling systems. The best option is to buy a product with a low noise level, which will not be heard behind the noise effects from the film demonstration;
4. Projection color gamut... It is independently regulated, but it must be borne in mind that all colors must be natural.

In addition, of particular importance is lamp life... As a rule, this parameter depends on the intensity of device operation: if you watch a movie every day for 1.5 hours, then the lamp will last from 3.5 to 7 years.

According to statistics, users change the lamp once, then the projector itself must be replaced with a more advanced model.

Light Emitted by Diode (LED)

LED lighting sources are used everywhere. There are low power led type projectors. The leading manufacturers of modern cinema projectors assure that new products will be on sale soon. Instead of an incandescent lamp, they will use color diode systems with a service life of up to 30,000 hours, that is, until the end of the life of the projector itself.

Replacing an outdated projection lamp with an LED at the present stage of development of technical capabilities is not a big deal, but only DLP projectors are suitable for working with LED light sources.

Leading companies use LED in conjunction with lCoS matriceswhich also work on the principle of light reflection. Their engineers assure that the dawn of this technology will come soon.

How the projector of the future works

At least three diodes are used: red, green and blue, yellow and blue are added so that the color rendition has a more saturated color. There is no light wheel in LED products - an electrical circuit is installed that switches backlight diodes imperceptibly to the eye, as a result you see a bright color picture on the screen.
Advantages:

1. Weight and dimensions... LED + DLP made it possible to place all the components as close as possible and create miniature projectors, no more than a box of CDs.
2. Energy consumption: LED consumes 10 times less than lamps and can run on battery power.
3. Life time... The lamp has no more than 3 thousand, LED - 20 thousand hours without reducing the brightness.

The disadvantages include only one thing: the best examples of led-type projectors have a luminous flux of only a few hundred lumens. This is only enough for creating small images in a slightly darkened room.

For example, BenQ's Joybee GP1 miniature LED projector can produce images from 38.1 to 203.2 cm diagonally in 4: 3, 16: 9 aspect ratios. It weighs 640 g, has a built-in speaker, D-Sub connector and a USB port for external storage.

Projector of the future

Let's briefly talk about the latest developments of the Japanese company Epson, which is part of the well-known diversified concern Seiko Group, which produces laser printers, scanners, PCs, tuners and other modern electronic products.

Projector technology based laser module instead of a classic lamp, it allows you to deliver quality that will captivate you with natural color and image clarity. Even the darkest scenes will be perfectly visible thanks to the high-speed contrast control.

Such a projector is absolutely maintenance-free; the module service life is 30 thousand hours.

What should be the distance between the projector and the screen?

Standard products require 2.5 to 4 m for the image to be clearly focused, but this distance is not acceptable for all rooms. In this case, it is necessary to purchase a short-focus apparatus that perfectly transmits an image at a distance of 1.5-2 m.

Pay attention to products that can change the focal length of the built-in optical system. Just install the device and make the necessary settings on site.

Such a projector has one peculiarity: the farther from the surface onto which the image is projected, the larger each pixel and, accordingly, the entire image will stand out.

Which device to choose?

For the price, the most acceptable option for a living room is the BenQ W1070 + with a very good image quality for 98 thousand rubles, which has become the hallmark of the Taiwanese company BenQ. A lamp with a brightness of 2000 lumens allows you to watch movies without dimming, the maximum possible expansion, a 3D image. At a distance of 2.5 m, we get an image with a diagonal of 100 inches (2.54 m), besides this there are other pleasant surprises: it works wirelessly, receives video using a module with a range of 30 m.

This model is BenQ's trademark and has won numerous awards and prestigious awards at exhibitions. In international ratings he is among the leaders.

For a more affluent buyer, there is a BenQ W6000 at a price of up to 128 thousand rubles, 3D glasses are included in the kit. Comparative characteristics of these two models are shown in the table:

BenQ has a 50% share of the global projection market despite constant attempts by competitors to tarnish its products in various ways. The preference of buyers still remains on the side of the Taiwanese company, while the quality and technical capabilities of the manufacturer continue to grow steadily. BenQ's engineering department uses nanotechnology and is constantly on the pulse.

Selecting the screen

In second place after the projector itself is precisely this device, without which home cinema does not exist. The screen can be purchased on a tripod stand. But experts offer the best solution: buy an inexpensive suspended version and fix it on the ceiling. This is a real space saver.

When buying, it is important to remember that Chinese experts have already copied all the screen models. Therefore, ask the seller for a certificate.

With special attention, it is necessary to pay attention to the material: products with a matte white coating or a light gray canvas have priority. They make it possible to place spectators and projection equipment more freely.

Choosing a place to install the device

Projector purchased, screen selected, remaining. There are many options for use: the device is installed on a coffee table, a high bedside table, or mounted on a special bracket to the ceiling.

Be aware of the subsequent serviceability and the availability of a replacement projection lamp.

An ordinary, led or laser home theater projector is designed to provide comfort and convenience for watching various films and video materials, so it should work silently, have excellent characteristics in terms of brightness, resolution and color rendering. Before heading to the store, check out the user reviews - you might like one of these top models.

Choosing a projector for your home or home theater is a rather complicated procedure; you will need to take into account a number of certain factors. A large number of models with different functions can often confuse buyers. The article will consider characteristics that will help simplify the purchase of such equipment.

Today these devices used in many areas... Home projectors allow you to enjoy watching a movie on a big screen at home or show a presentation at school or work. Wherein screen diagonal can significantly exceed 100 inches. The size of the projector is small so it can be easily placed in any living room. The home theater device operates with the lights off.

How to choose a projector

When choosing such a technique, you will need to take into account a number of nuances that will directly affect the quality of work and functionality. Brightness, color quality and contrast are key purchasing specifications. Additional properties are also worth paying attention to, as they often improve the experience of using it.

Brightness

The brightness of a home video projector is characterized by the amount of light it emits. So they say, because the brightness from the light source will vary depending on the screen size. This indicator is measured in lumens and can range from 2,700 to 20,000 lumens. It should be borne in mind that the brightness and contrast will decrease when you adjust the color rendering.

Also, the brightness may change depending on selected mode... Most models have vivid, presentation, and accurate modes. The last mode will have maximum accuracy and minimum brightness.

If the projector will be used under additional lighting, the brightness should overpower this background light. In high light conditions, the picture quality will fade into the background, the strength of brightness will be much more important. This indicator will directly depend and cost... If the projector is to be used in a dedicated darkened room, 700 lumens will be sufficient. For simple living rooms or other rooms, it is better to choose models with a brightness of about 2000 Lm.

Contrast

Under the contrast characteristic implied ratio black and white. This indicator affects the quality of the picture and the level of its perception by humans. The contrast level can be determined by image quality stationary objects or things in motion.

With a low value of this property, dark objects may merge with black, and it will be difficult to see them in the image. To avoid this you need adjust the gamma correctly for different viewing modes.

To assess the level of contrast, experts recommend consider the following factors:

• This characteristic is influenced by the level of lighting in the room.
• The contrast does not greatly affect the legibility of the display of the inscriptions under additional light.
• Color nuances are independent of contrast.
• Brightness is capable of neutralizing the lack of contrast under certain conditions.
• The declared level of this characteristic corresponds only when using the device in an illuminated room, especially for cheap ones.

Projection technology - types of projectors

There are a large number of technologies, each of which has its advantages and disadvantages.
The most common are the following matrix options:

• Cathode ray tubes... This technology includes the very first projectors, which were created back in the 70s. Such devices are distinguished by high resolution, but they do not have high brightness. Their weight and cost are extremely high, so they are practically not used at home.
• Liquid crystal... A completely different technology is used for these devices. The Epson brand is engaged in the production of such projectors. When creating them, three displays with a polysilicone base are used, this allows you to guarantee acceptable color reproduction and a long service life.
• Micromirrors... This technology allows for a richer picture in comparison with liquid crystal screens. This is achieved due to the smaller spacing between the mirrors, their reflection, and minimal loss of light. The principle of this technology is to consistently display colors on the screen.
• Three-matrix... In devices made with this technology, light is filtered when passing through mirrors. The disadvantages of this design include the lack of black color, possible matrix burnout and the lattice effect.
• Reflective Lcos... This technology allows light to pass through by opening or closing a reflective crystal. Most of these devices have a matrix with a resolution of 1365x1024. The disadvantages include the high cost.

Color rendering

This parameter characterizes smooth transition from black to any base shade. Also, the ability to adjust the color rendition will depend on it. Quality projectors allow you to adjust the white saturation to any base color. There is a possibility of regulating in increment or offset.

Lens

Often, most projectors output at right angles to the lens or with little vertical offset. This offset is called offset, but it is not always indicated in the specifications. Projectors middle price category have an additional horizontal offset that can be adjusted. AT expensive models such settings can be made with the remote control and stored in the device's memory. This feature will help you adapt the projector to a living room or other room of any size.

3D Mode

A significant disadvantage of watching videos with 3D is loss of power luminous flux of the device. So for this mode, it is better to choose a gadget with extra brightness.

Also, ghosting and flickering of the image is possible when viewing. In projectors for 3D implementation can be used active and passive way.

Resolution

This parameter characterizes the number of pixels in width and height that form the image. The higher the number, the clearer the picture will be at the same screen size. The budget models have a resolution of 800x600, the picture quality will be low. But the Full HD resolution (1920x1080) will allow you to enjoy watching the movie to the fullest.

Throw ratio

A home projector is best to choose with a function horizontal and vertical lens shift, which will move the lens and help in creating the correct image on the screen, even when the unit is installed in the corner of a room. In this case, the resolution and clarity of the image will not be cut.

Connectors and interfaces

This nuance is also quite important. Large number of connectors allow to connect additional equipment or acoustic system. To connect any set-top boxes, you must definitely choose a suitable video interface. The most commonly used connectors are DVI, VGA and HDMI. Also available possibility of purchasing adapters in case the interface does not fit.

Screens for projectors

The projection screen will help transfer the image to the screen without loss of quality... There are solutions with electric or manual control, portable and stationary. For home use, an electrically controlled stationary screen is the best choice.

How much does a projector cost

By cost, the following categories can be distinguished:

• Budget... Their price is within 1000 dollars. The disadvantages of this choice include the lack of brightness and contrast, as well as low resolution.
• Middle class... Devices under $ 3,000 have no significant drawbacks. In comparison with budget options, they differ in additional functions, optimal brightness and contrast indicators.
• Flagships... Devices over $ 3,000 have state-of-the-art ultra-high-resolution projection technology and excellent image quality.

A home projector will have an average cost of $ 2,000. Such a device will have an optimal price-performance ratio.

How does a projector work

The device connects to a computer, camera or other device with a suitable connector and broadcasts an image or video to a special screen. Projecting a picture is carried out according to one of the previously discussed technologies.
The principle of operation is as follows:

1. Laser or special lamp creates 3 color components that can be combined.
2. Then a sophisticated focusing and sweeping technology projects an image... This uses a mirror system.
3. There is an opportunity display a picture on any surface, including uneven ones.

The choice of the best projector depends primarily on its purpose.

Features of home projectors

Home theater projectors must be able to display high-quality dynamic scenes (such as movies, videos, sports) and provide equally good results for different sources or signal standards. Unfortunately, the implementation of these features costs a lot of money, and for models with a "natural" resolution in 4K - they are completely inadequate.

It's no surprise that manufacturers are looking for various clever ways to get high definition pictures without using expensive full-fledged 4K chips. JVC calls this technology "e-Shift", Epson calls it "4K Enhancement", Texas Instruments calls it "XPR" (Optoma projectors). In principle, they all implement the idea of \u200b\u200boptical shift of half-frames with subsequent superposition, just each in its own way. By the way, the benefit of such pseudo-4K is also when viewing less clear content. The same pixel grid (mosquito) dissolves almost completely. However, due to some loss of sharpness.

The specific requirement for home projectors can be minimum delay time - for gamers, this parameter is extremely important. Video format 3D is now capable of demonstrating the vast majority of models. The only thing that, to get a full-fledged home theater surround sound, you will have to buy a speaker system of the appropriate level.

Features of projectors for work and study

Educational goals and business needs involve working with static images. Consequently, projectors for offices and classrooms most often they can easily do without complex subsystems of hardware-software interpolation and scaling, color management and other expensive chips. Their matrices are focused on "computer" resolutions, and "cinematic" ones are displayed with a significant truncation of the used area. It is clear that the latter affects the clarity of the resulting image not in the best way. This group is also not without advanced functionality, but it takes specific forms. For example, support for interactive modes of operation.

General characteristics

The main interface for connecting projectors is HDMI, and many models are equipped with a couple of such connectors. If you have several signal sources, they will definitely not be superfluous.

Almost all projectors have learned to interact with smartphones and other devices using the MHL protocol. For convenient connection of portable equipment, they often have ports USB... Here, a useful functionality can be considered the ability to simultaneously charge mobile gadgets through this connector. It should be borne in mind that the presence of a USB interface does not mean the ability to work with flash drives. Such "buns" are only for projectors with built-in media players. Moreover, the latter is "smarter", the more video formats can be played offline.

Depending on the intended distance from the screen, projectors should be selected and along the "length" of the focus... The most short-focusing models are able to form an image with a large diagonal, being literally centimeters from a wall, canvas or board. On the other hand, such devices (as a rule) are not suitable for projection from a distance. Finally, the brightness of the resulting picture depends on a number of factors, the main among which are the distance to the screen, the power of the emitted luminous flux and the level of illumination of the room. For most home theater projectors and partially shaded rooms, a flux of 1500-2000 lumens is sufficient.

We present to your attention a selection of very worthy and popular models for various purposes in the category of inexpensive and medium-priced projectors, which have earned good reviews from buyers and experts in 2018. There cannot be completely universal solutions here, therefore, choosing the best projector for an office or for a home theater should be based on the range of tasks to be solved, as well as the expected conditions of its operation.

In the era of high definition technology, projectors are gaining in popularity as they allow you to recreate the atmosphere of a real cinema in your home. Of course, this idea can also be realized with a large LCD TV with 4K video support.

However, content with such a resolution is still rare, and TVs of this class are not cheap. Today's Full HD projectors are capable of delivering superb picture quality and take up significantly less space.

LCD vs DLP

Modern projectors use LCD (Liquid Crystal Display) and DLP (Digital Light Processing) technologies, which differ in the principle of image formation. In the case of DLP, a miniature mirror acts as a pixel. In front of the set of such “pixels”, a rotating filter is installed, divided into color segments.

The light is transmitted through a light filter, hits the mirrors and is reflected from them onto the screen. LCD technology uses matrixes that are illuminated by light reflected from a system of mirrors. Each mirror is a light filter and supplies only one of the three primary colors to the matrix.

Of course, both of these technologies have both advantages and disadvantages: for example, LCD projectors provide rich colors, and DLP solutions have higher contrast. Among the disadvantages of LCD-models, it is worth noting a smaller depth of black color, while DLP-projectors have a “rainbow effect”. However, in modern devices, these shortcomings are almost invisible.

In our various benchmarks, LCD projectors outperform DLP solutions by a small margin. As you know, the projection LCD technology was developed by the Japanese company Epson, and the first device based on this principle was created 25 years ago. All these years, the technology has been significantly improved and refined.