The Multimedia projectors for several years become popular all over the world. Their use on presentation and counsel, on lecture and in scholastic simulator, in home movie-theatre and conference hall, on disco and in club. Appears all more producers projector, but projectors themselves become brighter and easier. They find using in different area of the lifes. On work, and in education, and on rest projectors do our life an удобнее. What be видеопроекторы?

Technology production видеопроектора and defines his(its) quality

1. CRT (ELT) - most aging technology of the creation projector. The Main element of such projector are three electronic-beam tubes, which and form the scene. Average brightness forms 200-500 ANSI Lm. Value: high permit (before 2500 points), контрастность (more 1000:1) and splendid цветопередача. Only, the трехматричные DLP-projectors approach to him on quality of the picture when reproducing the videosignal. The Defect: big weight - 30-100 kgs, high cost - from $12.000 and above, difficulty of the montage and nastroyki. Recommended sphere of the using - home video.
2. CD-projectors - a main element data видеопроекторов is one or three LCD-matrixes, which work at bright spot, as film in motion-picture camera. Average brightness data видеопроекторов - 700-2500 ANSI Lm, but permit from 800х600 before 1280х1024. Value: small weight - from 2,5 kgs, high brightness and цвето-saturation, simplicity of the use, small price. Usually, LCD-projectors give visual more bright and saturated picture, than, for instance, DLP-projectors under same declared by producer to brightness. The Defect: difficulty with reproducing the black colour and halftone, a certain "мозаичность" scenes.
3. The Advisable sphere of the using - a demonstrations статичных and анимированных scenes though exist the copies, oriented on home movie-theatres. 3. DLP-projectors - a base data видеопроекторов is DMD-matrix, consisting of микрозеркал, which is illuminated consecutively by primary colors (RGB) and works at reflection. Average brightness 700-2000 ANSI Lm, permit from 800х600 before 1280х1024. Value: in contrast with LCD-projector, the best reproduction video and black colour, absence of the visible distances between point. The Defect: статичные to demonstrations and bright cartoons look at oneself usually a little worse, than on similar LCD-projector to account of smaller saturation. The Advisable sphere of the using - from presentation before home movie-theatre. Exist also 2-h and 3-h matrix DLP-projectors beside which quality well above, brightness - before 12.000 ANSI Lm, but also the price on them - from $25.000 and above. The Data to models видеопроекторов are used or on exhibition, or in greater movie-theatre, working with digital carrier.
4. D-ILA-projectors are built on technologies, offered JVC - LCD-matrix, working at reflection. The Projectors made on this technologies, have usually matrix by permit 1365х1024 or 1048х1536 point, brightness 1000-4000 ANSI Lm. Value: projectors possess the excellent контрастностью and saturation. The Defect: high price. The Advisable sphere of the using - ideal suit for demonstration high-quality graphs and film.
5. LDT-projectors - technology of their fabrication is founded on lazer. This is the most latest technology, industrial issue which will begin only in 2000 Inaccessible for the other technology parameters: brightness, контрастность, permit and the price (more $200.000) in several times above, than beside existing видеопроекторов. The Producers promise the more available prices to 2005.

Projectors CRT

Contains three radiating picture tube, creating on platform with colour люминофорами bright scenes small sizes in primary colour R,G and B. These scenes three lenses in optical independent channel проецируются on screen, where optical are exactly combined and form the general colour scene. This type projector exists more than 60 years and has the most high-quality amongst all projector picture. However all advantage CRT-projector to the ful possible to see when viewing only high-quality, professional video recordings in well obscured premises, on screen диагональю before 2 metres. CRT-projectors rather bulky (the weight, as a rule, more than 50 kgs) and require skilled and neat address. After any transportation they need for skilled adjustment for joining on screen three primary scenes. They Are Used in road club and небедных organization, since have a best permit and цветопередачу. They Are Used only as stationary device for small common-room

Liquid-cristal projectors

The Liquid-cristal projectors LCD - a most wide-spread variety projector, founded on using ZHK, LCD (Liquid Crystal Display) of the matrixes. Modern LCD-projectors use the термостойкие active ZHK-panels on полисиликоне (P-si TFT) and thin-film transistor TFT and reach the permits QXGA (2048x1536). The Process of the work LCD-projector in general type looks so: light flow at дихроичной optometrists is split on three forming (R,G,B) and is given on three matrixes, which form slide for each of colour hereon by means of again optometrists (the complex system of the prisms) light flow is going to together and through lens проецируется on screen. Understandable that, getting through просветные LCD-matrixes, light flow weakens, but matrixes are warmed. Exactly so for a long time LCD-projectors vastly yielded the modulation-type projector reflected light flow (ILA, D-ILA, DLP) on such main for projector factor, as light flow and контрастность, since greater light flow сильнее warmed the matrixes. The Other defect LCD-projector was big time of the delay (more than 45 ms) - time, for which fluid crystals of the matrix could change the position in space. This brought about that that contour trains appeared on screen for quickly moving fragment of the scene.

However using the active matrixes since time of the delay less 30 ms allows проецировать change the scene practically real-time. Use полисиликоновой to technologies in production LCD-matrixes, which allows the matrix to bear the more high temperature, and hereupon use in LCD-projector powerful металлогалогенные lamps. In each pixel of the matrix on полисиликоне is used transistor of the smaller size, due to that light easier passes VWXbe drafty matrix. All this has brought about that that LCD-projectors today reached brightness 7700 ANSI-люмен and even above that allows to use them even for professional using (for instance, in movie-theatre). The Company Sanyo, for instance, with the help of special mechanical device combines two LCD-projector for collaboration, their light flows form and reach the values 14000 ANSI-люмен and above under контрастности before 1000:1. On correlation price capacity LCD-projectors are the most best. Probably so they and are the most mass and bought мультимедиапроекторами (before 70 % volumes market). In высокоэффективных projector are used so so-called convertors полязизации, for instance, Polarized Beam Splitter (PBS) in projector Sanyo, which principle of the work is illustrated on drawing.

Besides, all more broad using find and other optical components, so named микролинзовые rasters, for instance, Microlens Array, servicing each pixel of the scene, conditionally shown on fig. in the manner of simple конденсорных of the lenses on LCD panel directly. Their device is shown on drawing.

Here, each cell микролинзового raster focuses passing through corresponding to pixel light by so as he does not виньетировался the opaque surface of the substrate, occupied controlling field transistor.

And however to here new nor was thought up, don't care this does not avoid two principle defects projector with x-rayed LCD panel. In described optical system they work with getting through them light flow, absorbing i.e. diffusing in the manner of heats not missed his(its) part. Besides here impossible reach the absolute transparency of the pixels because of presence in them opaque component of the electronics, for instance, токопроводящих conductor, greatly reducing efficient area пискселя. Practically she grows shorter on 30-50 % depending on sizes of the pixel and efficiency микролинзовых raster.

Main features LCD-projector

The Main technical feature projector are brightness and supported permit, as well as контрастность and size. Brightness modern projector varies within from 600 before 7700 ANSI-люмен. Some producers, combining light flows two ganged projectors, obtain brightness in 14000 ANSI-люмен. The Projectors with light flow 600 ANSI-люмен are used in obscured premiseses with screen before 100 diagonally (the width - 200 refer to, height - 150 refer to).

To use the projectors in незатемненных premiseses, exists the formula of the calculation to brightness depending on size of the screen: if light flow of the projector in 500 once exceeds the area of the screen with good covering, that his(its) brightness will correspond to brightness of the screen greater colour television set. For instance, for screen by size 150х200 refer to that is to say 3 square metres, ideal will be a projector with brightness 1500 ANSI-люмен. But even in this case straight line засветка screen, particularly solar, must be excluded. Usually correct decision is an installing the screen in obscured niche or corner, in which out-of-work light while rest premises can be not obscured. All modern projectors are equiped with вариообъективами, which allow, not moving projector for screen in a certain range, change maximum and minimum of the scene diagonally. As a rule, projectors by brightness 600-1000 ANSI-люмен can проецировать maximum size of the scene before 200 diagonally (the width - 406 refer to, height - 305 refer to), brightness 1200-2500 before 300 diagonally (the width - 610 refer to, height - 457 refer to), but the most bright projectors 2600 ANSI-люмен and above can проецировать maximum scene before 400 diagonally (the width - 812 refer to, height - 610 refer to). When functioning(working) two-set projector by brightness 5200 ANSI-люмен and more maximum size of the scene can reach 600 or more than 15 metres diagonally! The Distance from projector before screen usually forms minimum 1,4 m, and size of the scene does not exceed 30-40 diagonally, but greatly - before 15 m. When distance before screen can not be big, use additional короткофокусный lens with zoom (for instance, in room for negotiations) that allows to enlarge the size to projections. When before screen more, than 15 m, use additional длиннофокусный lens with zoom (for instance, big conference hall) that allows to focus scene on screen

The Second most most important factor видеопроектора is his(its) permit. On this factor all projectors are divided on SVGA, XGA, UXGA-projectors with permit accordingly 800х600, 1024х768,1280х1024. Under maximum size of the scene size pixel can reach 1х1,5 refer to so if be too close to screen, possible see пикселизацию scenes. It Is Considered that border to differentiality separate pixel screen scene is found on distance 1,5 m. So, for instance if width of the screen forms 2 m, that spectator is not recommended be closer, than in 3 m from screen. Today in LCD-projector are used LCD-panels size 0,7; 0,9 and 1,3 inches. The Sizes pixel in XGA-matrix are reduced before 18х13 мкм. An efficient area pixel has Under so small size big importance with provision for his(its) opaque area that is to say real participating in inflexions passing light flow. The Problem of the increase to efficiency pixel dares use an микролинзовых raster, focusing passing light flows in the centre each of pixel so that light flow avoids the opaque area and increases on 40% more then. Some are a known producers today use technology an микролинзовых raster commencing even with younger models projector (for instance, Sanyo).

For projector by of no small importance factor is контрастность - an attitude of luminosity at demonstrations white and black flap. Beside many companies of the producers this factor is declared from 400:1 before 800:1 and above. Though this and not quite so. Test test in Laboratory of the facilities of the image to information (Moscow, are published in journal PC Magazine RE # 12/2002) have shown that контрастность, measured under factory installation, more or less corresponds to (or even above) declared by producer. But here is контрастность, measured with exposed by gray wedge (as follows this factor and influences upon depth of the perception and succulence of the paints of the scene, since this test guarantees the image whole sulphur градиентного of the wedge), can differ before half from declared factors in the most worst side (beside some projector and more. Under that that there is models, beside which at test контрастность even above declared by producer parameter).

There is differences and on brightness (the light flow), declared by producer and measured by real light flow. Beside majority of the producers difference between declared and measured by light flow forms from 15 before 20 %, but beside some - nearly 50%, in smaller side i.e. when buying the projector by declared brightness in 1000 ANSI-люмен possible gain the projector by brightness in 850 and even in 550 ANSI-люмен. Such a facts.

The Last, important factor of the projector - a weight and his(its) size. The Weight LCD-projector varies from 2,5 kgs (the size from 298 h 84 h 215 mms) and before 17 kgs (the size 439х277х604 mm). Average weight of the average projector forms from 3 before 5 kgs, and he liberally fits in bag from beneath ноутбука (even along with cord). The Portable projectors by weight before 3 kgs much comfortable carry together with ноутбуком in one briefcase, but presence of the portable screen on tripod allows to organize the presentation or lecture in any place practically, without person of preparation. More gabarit projectors, as a rule, use stationary, placing, as a rule, on fastening under ceiling. At possibility to install the projector in the middle common-room (after all focal length is numbered in 15 m or slightly more with special lens), as well as fix the projector on ceiling (for instance, on year platform), projector possible to put(deliver) behind special просветного of the screen. All these metamorphoses with scene allow to do the additional functions a projector (basically to account digital effect).

Mikrozerkalinye projectors DMD

The Chip DMD presents itself light modulator, consisting of matrix thumb aluminum mirror, which amount corresponds to the optical permit of the projector. The Mirrors by size 16х16 мкм bear up on substrate by means of mechanical подпружиненных подвесов, allowing him to turn round within 10 degrees, as shown in drawing.

On each микрозеркальный pixel подведены control and pair address electrode united with cell SRAM on KMOP substrate. The Combination controlling and address voltages электроста-тически declines the mirror to one of the extreme positions, corresponding to conditions "is included" and "is switched off". In the first event reflected микрозеркалом light falls into optical system of the projection lens, but in втором scatters and is absorbed. Control position mirror is realized by method to digital width-pulse inflexion with frequency by flap, but level color forming light flow on each pixel is defined by relative time of the finding his(its) микрозеркала in included position on temporary interval of each television field. Length last (20 ms for television systems 625 lines, 50 flaps/with, beside 17 ms for seen on screen of a part of raster) is subjected to 10-class sampling by electronics DLD projector, which provides 1024 levels of the light flow each pixel in channel primary colour. Rest is based on physiological ability of the vision to average instant brightness and color tone of all pixels of the screen scene. That this was got better, is used increase the frequency to switchings of the pixels by by transformations long pulse enabling the pixels in collection more short same total length within each field.

Exist two varieties DLP-projector: with three DMD and with one DMD. In the event of with three crystals DMD (on one DMD on each primary colour R,G,B) scene is got more bright, with high контрастностью, is since reflected from mirror practically whole light flow loss-free. Additionally time of the optical switching the conditions микрозеркал does not exceed 2 мкс (10 мкс with provision for fading the connecting processes). As a result essential advantage DLP-projector is an absence on screen contour train for быстродвижущимися fragment of the scenes that because of clumsinesses of molecules fluid crystal exists beside projector with ZHK-panel. Beside DLP-projector is absent also effect засветки white pixel nearby black that provides the best transmission contrasting transition and fine line. On all parameter DLP-projectors with three DMD are best in its class. However because of that that block DMD (which is sold for producers projector company Texas Instruments in the manner of finished module Optical Engine, containing chips DMD, electronics of control and optical system with the source of the light and ventilator) is a device more complex, but therefore expensive. The most wide-spread (and comparatively inexpensive) projector DLP are a projectors DLP with one DMD. When using only one микрозеркальной of the matrix DMD increases the load on vision because of that that scene on screen appears consecutively in each of three colours. The Process looks as follows: between the source of the light and matrix DMD is found revolving светофильтр, containing three colour sectors (recently started to use and with four sectors - three colour and one transparent), and on эране is alternately formed scene for each colour. However brain perceives the holistic colour scene. This possible, since our vision has determined inertia . The Frequency of the change colour forms 150 Hz (180 Hz for system NTSC) that not always is it is enough for exception visual artifact. The Spectators, which long time look DLP-projector with one DMD, note certain утомляемость visions. In this connection possible confirm that scene одночиповых projector DLP vastly yields the трехчиповым. And however to account of high brightness and контрастности projectors DLP with one DMD are second on распространенности in the world (before 30% market projector) subsequent to LCD-projector.

Author: А. V. Savin It Is Added: 03.05.2007