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About Projector Technology

Projectors are not all the same, not just becuase of the obvious difference in brightness (lumens) or resolution but the technology that drives them is also different. We get asked every day which is the best and we are sorry to say that the debate will continue. It really depends on the colour accruacy you require, the brightness of the projector and of course your budget. Rather than give our vote to one technology of the other this projector information page looks at the technology, explains it and then gives benefits against each of the other technologies. However whether you by a LCD or 3 chip DLP you will have made a decision to purchase stunning quality on large scale. If you can afford to buy a LCOS projector then you will get the benefits of both LCD and DLP. In regard to LED this technology is in its infancy and the lumens output really only makes it suitable for single users, however watch this space as LED will be a force to reckon with in the near future.

3LCD or LCD- Projector manufacturers like Epson Sanyo Eiki Canon 

LCD Basics
Liquid Crystal Display pass light through LCD panels about the size of a postage stamp; the LCD panel is made up of miniscule panels ('pixels') that can be clear, opaque or some semi-clear point in between. These pixels take the form of the image to be created, and the light passes through the clear or partly-clear areas in the same way that light passes through the clear or grey parts of a negative.

The projector's lens, in turn, expands the image and directs the light onto the screen or viewing surface. This enlarges all the tiny details and creates clear, detailed and beautiful images with ultra-smooth movement. 

3-panel LCD System
A projector with the designed 3-panel Liquid Crystal Display ('3LCD') system uses dichroic mirrors to break the white light from the lamp into red, green and blue light. Each of the three colours of light is then passed through its own LCD panel and then recombined by a prism before being projected onto the screen. The result is smooth-moving images with rich, full colour, since all three basic colours are included in each pixel of the projected image at all times.

The Technology Behind the Internal Prism

All 3LCD projectors use a 3-chip, solid-state optical engine to deliver incredibly bright, true-to-life colour, creating an astonishing level of realism with every viewing. Projectors powered by 3LCD technology have 3-chips and a solid-state optical design, so there is no colour breakup or “rainbow effect.” With the fast-paced development of high-definition, rich colour video and projection content, the quality and impact of the colour produced by a projector has become extremely important. To date, buyers and users have had no way to determine if their projector is capable of producing rich, vivid colour however  this can now be measure by colour light output.  Colour Light Output is a metric that measures a projector’s ability to deliver colour. Developed by colour scientists using the same approach as White Light Output (Brightness) measurement, Colour Light Output provides a simple, accurate and easy-to-understand way to evaluate projector Colour Performance. Why is Colour Light Output Important? Colour Light Output is critically important because colour is a key indicator of picture quality. Colour Light Output provides users with a way to evaluate a projector’s Colour Performance to make better buying decisions.

3LCD seem to have a lower contrast ratio but that can be confusing as Contrast Ratio and Resolution give no information regarding a projector’s ability to reproduce colour. 

Incredible Detail- Smooth, seamless colour combined with an unparalleled greyscale range delivers incredible detail to every image displayed by a 3LCD projector. Greyscale is the shades of grey (from black to white) required for greater image depth and detail; it allows greater variation in shadows and brings superior accuracy to colour, creating a jaw-dropping, true-to-life visual experience.3LCD technology delivers sharper and brighter images with superior greyscale detail, as they  efficiently use light to project to the screen with no colour disruption.

Reliable Technology- LCD technology surrounds us – HDTVs, PDAs, mobile phones, monitors and more. With more than 50 million 3LCD chips shipped worldwide for projection, this powerful and road-tested technology is the optimal way to achieve the sharpest and most beautiful images

Replaceable filters Projectors, like all household electronics, are also prone to dust buildup. They are used in a variety of indoor environments, and can be affected by chalk dust in the classroom or standard household dust in a home theater setup. By preventing dust from reaching the projector interior, you ensure your investment will deliver better performance and a longer life.3LCD produces projectors that come with a replaceable air filter designed to trap pollutants on the filter surface, before they reach interior parts.  

DLP Technology

Not all DLP's are the same, which is a bit confusing.

How DLP works

At the heart of every DLP® projection system is an optical semiconductor known as the DLP® chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987. 

The DLP® chip is probably the world's most sophisticated light switch. It contains a rectangular array of up to 2

 million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair. When a DLP® chip is coordinated with a digital video or graphic signal, a light source, and a projection lens, its mirrors can reflect a digital image onto a screen or other surface. The DLP® chip and the sophisticated electronics that surround it are what we call DLP® technology

The greyscale image

A DLP® chip's micromirrors are mounted on tiny hinges that enable them to tilt either toward the light source in a DLP® projection system (ON) or away from it (OFF)-creating a light or dark pixel on the projection surface.

The bit-streamed image code entering the semiconductor directs each mirror to switch on and off up to several thousand times per second. When a mirror is switched on more frequently than off, it reflects a light grey pixel; a mirror that's switched off more frequently reflects a darker grey pixel.

In this way, the mirrors in a DLP® projection system can reflect pixels in up to 1,024 shades of grey to convert the video or graphic signal entering the DLP® chip into a highly detailed greyscale image.

Adding colour

The white light generated by the lamp in a DLP® projection system passes through a colour wheel as it travels to the surface of the DLP® chip. The colour wheel filters the light into red, green, and blue, from which a single-chip DLP® projection system can create at least 16.7 million colours. And the 3-chip system found in DLP Cinema® projection systems is capable of producing no fewer than 35 trillion colours.

The on and off states of each micromirror are coordinated with these three basic building blocks of colour. For example, a mirror responsible for projecting a purple pixel will only reflect red and blue light to the projection surface; our eyes then blend these rapidly alternating flashes to see the intended hue in a projected image.

Applications and configurations

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1-CHIP DLP® PROJECTION SYSTEM
Televisions, home theater systems and business projectors using DLP® technology rely on a single chip configuration like the one described above		 4-chip DLP® projection system
3-CHIP DLP® PROJECTION SYSTEM
DLP® technology-enabled projectors for vey high image quality or very high brightness applications such as cinema and large venue displays rely on a 3-chip configuration to produce stunning images, whether moving or still		 4-chip DLP® projection system

DLP have launced the Brillant Colour Projectors in a bid to take the claims that LCD provide better accruacy of colour

Color accuracy is paramount to a quality image. BrilliantColor™ not only improves color accuracy, it brightens secondary colors as well. This combination produces a new level of color performance that increases color brightness by up to 50% over other technologies and provides accurate true to life images.

DLP® projectors are famous for producing an incredible picture. Advances in BrilliantColor™ technology, which is now available in many DLP® projectors, are setting a new standard in colour performance. See why DLP® projectors are the best choice for business, education, home theatre, and much more.

DLP® Projectors with BrilliantColor™ technology feature multi-color processing to produce stunning, vibrant colors on the screen. Unlike other technologies such as LCD which use just 3 primary colors to produce the image, DLP® Technology with BrilliantColor™ uses up to six separate colours.

Colour accuracy is paramount to a quality image. BrilliantColor™ not only improves colour accuracy, it brightens secondary colors as well. This combination produces a new level of colour performance that increases colour brightness by up to 50% over other technologies and provides accurate true to life images.

LCOS Technology- Canon and JVC

What is LCOS technology?

Well, you could think of it as a hybrid between LCD and DLP. LCD uses liquid crystals, one for each pixel, on glass panels. Light passes through these LCD panels on the way to the lens and is modulated by the liquid crystals as it passes. Thus it is a "transmissive" technology. On the other hand, DLP uses tiny mirrors, one for each pixel, to reflect light. DLP modulates the image by tilting the mirrors either into or away from the lens path. It is therefore a "reflective" technology.

LCOS combines these two ideas. It is a reflective technology that uses liquid crystals instead of individual mirrors. In LCOS, liquid crystals are applied to a reflective mirror substrate. As the liquid crystals open and close, the light is either reflected from the mirror below, or blocked. This modulates the light and creates the image.

LCOS-based projectors typically use three LCOS chips, one each to modulate light in the red, green, and blue channels. In this it is similar to an LCD projector which uses three LCD panels. Both LCOS and LCD projectors deliver the red, green, and blue components of the light to the screen simultaneously. There is no spinning color wheel used in these projectors as there is in single-chip DLP projectors.

LCOS technology is usually very high resolution, and typically higher in price than most LCD and DLP products. There is no such thing as an SVGA resolution LCOS projector, and we know of only one very rare XGA resolution machine. Generally LCOS machines begin to appear in the SXGA (1365x1024) resolution class and higher. So by definition they are not cheap.

Nor are LCOS projectors particularly compact as compared to portable LCD and DLP units. The lightest LCOS machines to date weigh about 12 lbs. But they can get much larger and heavier than that.

So due to inherent high resolution and larger form factors, LCOS technology has not yet been adapted for cheaper mass-market portable projectors. Todays' LCD and DLP projectors sell in much higher unit volumes and are more appropriate for mobile presentation, classroom, and inexpensive home theater. For this reason LCD and DLP technologies get a lot more attention. Since LCOS does not sell in the volumes that LCD and DLP do, many assume it is not as good as LCD or DLP. Nothing could be more wrong. Many well-informed videophiles seeking the most elegant home theater solutions opt for products using LCOS technology because of its unique blend of performance characteristics that neither LCD nor DLP offer.

The Advantages of LCOS

LCOS projectors have several key advantages over the more popular technologies. First, due partly to inherent high resolution, and partly to high fill factors (minimal space between pixels) on the chips, visible pixelation on an LCOS machine is nonexistent. Even close up the pixel structure is less visible than you get with the high resolution 1280x720 DLP Mustang chip. So the resulting video image can be smooth as silk.

Second, with LCOS the pixel edges tend to be smoother compared to the sharp edges of the micro-mirrors in DLP. This gives them an analog-like response, whereas micro-mirrors add high frequencies that accentuate their digital nature. In practical terms, this gives the LCOS image a smoother, more natural look and feel, while DLP tends to impart a synthetic sharpness to the image that some would describe as harsh. (On the other hand, some people prefer the sharper image that DLP delivers. This is a matter of personal taste.)

Third, LCOS and LCD projectors deliver continuous red, green and blue simultaneously onto the screen. Single-chip DLPs deliver color sequentially, alternating between red, green, and blue one color at a time. Though DLP projectors can be capable of delivering rich, well saturated colors, both LCOS and LCD products tend to be superior in this regard. We believe this is due to the way color is managed sequentially in the DLP machines.

Fourth, the absence of a color wheel means there is no chance of you or anyone you invite into your theater being bothered by rainbow artifacts, eye-strain, or headaches that some people can be susceptible to when viewing single-chip DLP projectors. This is normally not a problem for most users of DLP products. And the more expensive high-end DLP systems have higher speed color wheels that further reduce these side effects as well as the percentage of the population that are bothered by them. But the lack of a color wheel in an LCOS projector eliminates the problem entirely.

The Limitations of LCOS

The primary weakness of LCOS technology is contrast. Currently most LCOS products are rated in the range of 500:1 to 800:1. So they do not have the contrast performance that most DLP products are able to achieve. The use of the new high contrast screen materials helps offset this weakness to some degree. And if there is indirect ambient light in the viewing space, the differences in contrast become much less of an issue.

Many LCOS projectors also have limited lamp life in the 1000 to 1500 hour range. And on certain models lamp replacements can be much more expensive than they typically are with LCD or DLP projectors. So these details should be checked before a purchase is made in order to get a clear idea of the cost of ownership.

Variations in LCOS designs

Though LCOS is a generic term, there are several different variations. The most popular LCOS implementation so far is that from JVC, which the company calls D-ILA, for Direct Drive Image Light Amplifier.

LED

What is an LED projector? That’s obviously the first question. LED (light emitting diodes), is not a technology that will replace, DLP, 3LCD, nor LCoS.Rather it is a lighting system for any and all of those projector types. So far, there are apparently several being shown, all called Pico LED projectors, but most using a DLP chip (although one with LCoS), with light provided by LED. The thing is, they are tiny!

 

At the moment LED have had a hard time. Certainly, they’re cool, but when you can buy a DLP projector for less than twice the price, that is 20 times brighter, and only about 4 times the bulk, and still under 2 pounds, not much demand, for a very dim smaller model. it just doesn’t work that great as a business presentation projector.Yes, projectors that weigh only an ounce or so.  

The Toshiba LED projector is less than 4 inches long and 2/3 inch high and it isn’t even one of the smaller ones.

True, they are really dim - 8-15 lumens right now, but sufficient to produce a reasonable looking image in a dark room, as large as 40 inches diagonal, they claim, but let’s say they can do 8-10 inches diagonal with some wash out in a moderately lit room, and probably do a decent job at 20 inches diagonal in a fully darkened room. Now, for something that falls in size and weight, about half way between a chapstick, and a pack of cigarettes, that’s impressive.

 

Optoma LED projector is the worlds first commercial thumb-sized projector

Imagine watching a U-tube video, as a 15 inch image instead of a 4 inch one on an iPhone or MP3 player with large display. Even better, watch a downloaded movie or TV show…

And that’s just the integrated side of the tiny LED projector market. Stand alone projectors, such as two I saw demonstrated there, were roughly the size of a Bic lighter (but thinner and a touch wider), or a large USB thumb drive (bigger than most of those). We are talking small. Think something no thicker than an iPhone, about 1/2 the width, and maybe 2/3 as long (that means an iphone is about as bulky as 3 or 4 of these combined. LED  will get brighter. Wait until they combine LED projectors and lasers for dynamic feedback, such as projecting a full sized keyboard and recognizing the keys as you “touch” them. That may well work for full speed typing on an iPhone or other small device. Now that really makes you wonder if we’ll still need laptops in a few more years.

  

Comparsion between the two main technologies- DLP Versus 3 LCD

 Colours

Projector A  3LCD Projector B- 1 chip DLP. Clearly projector A the 3LCD is producing better colours but DLP are fighting back with more segment wheels on the DLP. So if a projector has 3 colour segment wheel or 7 colour segment wheel the higher the number the closer it wil be to LCD colour quality. Also it matters if the dlp is a 1 chip or a 3 chip.


Rainbow Effect

DLP using a colour wheel that spins around this can cause something known as the Rainbow effect. These 1-chip sequential colour projectors use a rotating colour wheel that spins at a
rapid speed and displays colours sequentially. For some users this results in images displaying colour break-up or “rainbow effect,” which can be annoying and distract from the viewing experience. Projectors powered by 3LCD technology have 3-chips and a solid-state optical design, so there is no colour breakup or “rainbow effect.” Not all people are affected by this and as DLP technology gets better the occurances are reducing.

Screen door effect

The "Screen Door Effect" was noticed on the first digital projector, which was an LCD projector, made in 1984 by Gene Dolgoff, the inventor of the LCD Projector. To eliminate this artifact, Dolgoff invented "Depixelization", which used various optical methods to eliminate the visibility of the spaces between the pixels. To reduce this there are several options. First, DLP projectors suffer from this effect less than LCDs because, due to the nature of the panel design, the control circuitry isn't as large. More of the chip's surface is used to transmit light. Another option is to reduce the size of the individual pixels by using a higher resolution projector. Get those black lines small enough and you won't be able to see them.

Filter Free

In schools, conference rooms, auditoriums and in your home, LCD projectors require filters to keep dust out. These filters must prevent possible degradation to the optics and LCD panels. DLP® projectors enable sealed optics which do not require filters. The result? Lower maintenance needs which typically translates to significantly lower operating costs

Frequency for cleaning a projector’s filter is normally every 100 - 300 hours (1x every month to three months) and replacement of the filter is often recommended at each lamp replacement (Every 2,000 - 3,000 hours). Filter-free DLP® projectors eliminate the need for this periodic maintenance cleaning and replacement.

Home Cimena

DLP Cinema® technology is redefining the movie-going experience with an incredible all-digital experience. DLP® technology brings similar advantages to projectors, razor sharp picture, amazing video, incredible color and brightness. DLP® technology creates a picture so real and seamless — it's easy to forget that you aren't in the action. Ideal for sports and gaming, the ultra-fast DLP® chip has an unparalleled 16-microsecond pixel response time that allows DLP® technology to keep up with video on a level that other technologies cannot match. Watch one minute of sports on any projector powered by DLP® technology to see the difference for yourself

Lightweight

DLP® technology is the leader in lightweight projectors. Small enough to fit in the palm of your hand, the DLP® chip, is perhaps the most powerful display technology. It is the only display technology on the market that can enable the world's smallest projectors under 1-lbs., and light up the largest movie screens up to 75 feet. LCD projectors require 3 panels, while DLP® business and home projectors use only 1 panel, allowing manufacturers to design smaller, lighter and more innovative projectors.  However DLP projector can appear to get hotter than LCD's as there is less room for the fan to circulate the air.

Contrast Ratio- we have put this last as we are somewhat bemused by the contrast ratio's that some manufacturers claim to havebut cleary DLP does produce a higher contrast ratio.  DLP® uses a streamlined optical system that efficiently reflects light to the screen, resulting in a stunning viewing experience - crisper whites, ultra-rich blacks and images that "pop" on-screen, making it ideal for

The Essential Projector Guide - Click to find out everything you ever needed to know about Projectors. How to choose the right projector, how the differences in technology effect you. Explanation of Projector terms and what that means to you.

Projectors are what Just Projectors have been specialising in for the last 10 years. To understand what the benefits are of a projector , it is useful to know exactly what a it can do and also the different type of technologies which will help you decide which one  maybe say more useful as a business projector rather  than say a home cinema projector set-up. Firstly  what is a projector;  it is in fact an electrical device that when light is integrated with an optics system then the end result is a large image being displayed from say a computer , video source or a games console.  Projectors can be manufactured in 3 main types, LCD, DLP and  Lcos  .

DLP Projectors- which stands for digital light processing is the newest entrance and it has  revolutionised not only the pricing but also the longevity of the projector. So what are DLP Projectors, well Texas Instruments back in 1987 developed the DLP chip.  As with all things in the projector world things have moved on, in March 2008 the new DPP1500 chipset was developed which has brought about the Pico or micro projectors which amazingly means that it can be the size of a mobile phone, although it is time to say that these micro pico projectors still need to improve their light output to really be taken seriously.

DLP Projector have the advantage of being cheaper to make, hence a cheap projector price is available, the projector lamps do not deteriorate over their lamp life and the actual projector lamps are themselves in the region of £115 rather than a price tag of £220. So DLP projectors work in a different way from LCD Projectors

DLP  work by thousands of mirrors set out in an array of pixels to replicate the projectors resolution. Each mirror is thinner than a firth of a human hair. With the use of hinges the dlp chip mirrors create light and dark pixels by being either off or on. The white light generated then is shone through a colour wheel of up to six colours. The human eye sees all the colours and the result is a full colour image.

Features about DLP Projectors are that they do not require you to maintain the projector regularly as they do not any filter. They are able to achieve high contrast ratios which means blacks are black which is a particular favourite for a home cinema projector user.  So after reading all this about DLP projectors you might wonder why we sell other types of projectors such as LCD or Lcos Projectors, the simple fact is that often the colours are not as accurate. Benq, Acer, Optoma and Viewsonic are the main manufacturers of DLP.

LCD Projectors have been in existence longer than any other technology. The colours on these are extremely accurate and if you need a projector for use as a photographer or graphic designer then we would always recommend a LCD Projector. How does an LCD or sometimes known as 3LCD projector actually work, well there are three liquid crystal panels , a lamp , prism and filters. In lamp shines white light through a polarizing filter, then a series of dichroic mirrors .The three colour red, green and blue are then sent to a separate LCD panel; remember there are three of them. From there the LCD panels send the light through the dichroic prism which recombines the light and sends it out the main lens in the LCD projector to the surface against which it is projected. Each LCD can control one colour. So if you were to see a picture of a red plane against a blue sky, the green LCD would block the light from passing to the dichroic prism and out the lens. This is very technical but the upshot is that accuracy of colours is the key reason why people choose LCD projectors.  The projector lamp prices are higher and there is often deterioration over a period of time but the quality of an LCD is superior to a DLP Projector and when buying a HD home cinema projector that is what Just Projectors would recommend. The main manufacturers for LCD are Epson, Sanyo. Hitachi and higher end Mitsubishi.

Lcos or Liquid crystal over silicon projectors are a hybrid of LCD and DLP .  LCOS will produce the most accurate video that is capable of far better than either LCD or DLP. How does Lcos projectors work, light passes through these LCD panels on the way to the lens and is modulated by the liquid crystals as it passes. Thus it is a "transmissive" technology. Lcos uses liquid crystals instead of individual mirrors. Three LCOS chips, one each to modulate light in the red, green, and blue channels which is like LCD panels  The end result is a very high resolution image, they tend only to start at SXGA (1365x1024). So if the technology is so good why aren’t all projectors made that way, the simple reason is price, which out of the reach of most people who are buying a business projector. The contrast ratio on a Lcos projector is often restricted to around 500:1, lamp life is often shorted with them not achieving much more than 1500 hours so cost of ownership tends to be very high. And finally they are not any ultra portable Lcos projectors .LCOS  technology is usually very high resolution, and typically higher in price than most LCD and DLP products. There is no such thing as an SVGA resolution LCOS projector, and we know of only one very rare XGA resolution machine. Generally LCOS machines begin to appear in the resolution class and higher. So by definition they are not cheap to produce as are not many are sold there are few volume efficiencies achievable. If you can afford Lcos then the well-informed people buying home projectors will recognise that Lcos projectors have a lot to offer as they have all the benefit of LCD but without as the pixels are significantly smaller there is no chicken wire effect. Also the pixels are much smoother then DLP sharp edges, which again helps provide the smooth image quality. Typical manufacturers of Lcos projectors are Canon and JVC

So now Just Projectors have explained how projectors work and the different types of technology it is important to work out which one is suitable for your needs. There are 5 main choices you have when buying a projector; what resolution, what brightness, what technology, what inputs can it take and what is the throw ratio. Looking at all of these in turn.

Brightness is measured in Ansi lumens, this is standard that every projector is measured against so that you know if its 3000 Lumens then its brighter than say a 1500 lumens. It is not true to say that a brighter projector is always better as especially for home cinema projectors you would really be looking for a high contrast and the more lumens then that will reduce the contrast available. So it’s important to get the right lumens for the right requirement. We typically recommend 1200-1800 lumens for home theatre and over 2000 lumens for the business projectors. Education projectors often tend to be lower lumens but in recent months it seems that 2000 Lumens now is the minimum requirement. If you have an audience size of more than 50 people which in turn means you need a larger projector screen then the lumens output should be in the regard of 3000 lumens. Large venue projectors or projectors for meeting rooms should be around 3500 lumens upwards. If you are a mobile projector user then lower lumens is often acceptable as you are trying often to have ultra light projectors which usually are no so bright. With the emergence of Ultra short throw projectors then the lumens output can be reduced as the image doesn’t have to travel so far to get to projector screen and the ambient light has less effect on the projector image. Typically ultra short throw projectors are around 2000 lumens.

Resolution is the number of pixels that the projector displays its native resolution. Often projectors will claim to be SXGA projectors but in fact that is not their native resolution and some compression is taking place. The lowest resolution that is acceptable is SVGA (800x 600). These are the cheapest projectors and really you should only buy these is you have a very low budget. Take a look on your computer and change the display to see what SVGA resolution looks like and you will see that it is quite poor. If however you only want to use a it for showing Dvd’s or video content then a SVGA projector would be suitable. We sell more XGA projectors (1024 x 768) than any other type; although surprisingly this isn’t the resolution most people pcs or laptops run at but as these are the most affordable and there are more of these than any others available.  WXGA projectors (1280 x 720) are increasingly becoming popular now that people are beginning to enjoy viewing presentation is wide screen format. WXGA projectors also have the benefit that they mimic a HD resolution 720p, so if you wanted to have a business projector but also take it home and maybe use it for gaming then it would be more suitable than an XGA projector. In the last few years people have wanted HD projectors to view TV, play games or look at blu-ray dvd’s. In the past these have only targeted the home cinema market but there is now an emergence for HD projectors for graphic design and web design companies. The increased brightness of say the Optoma EH1020  with its 3000 lumens and 1080p projector HD resolution is a prime example of how the market is changing. Canon in the past have really had the corner on the SXGA+ (1400 x1050) projector market with their Canon XEED range but again with the HD range increasing this seems to be a less popular resolution. We do however still recommend SXGA+ projectors for camera club and photographers mainly because they use the Lcos technology which has been previously explained above.

Inputs on a projector are so important so do not ignore them when buying.. All machines will be supplied with composite video (yellow) connection which is the simplest but poorest quality signal. All are supplied with at least one VGA or also known as RGB connection which links to your laptop or pc. The better ones have two VGA inputs which always you display more than one input source at a time. Having a VGA output is useful when you want to display both your projector image and also to be able to view your monitor at the same time.  Component video or BNC which is the red/green/blue connection is a much higher quality than the composite video as it provides a correct display of the signal

S-Video is a standard connection supplied and like composite it is used for video it does slightly differ as it splits the video signal into two different components: Luminance and Chrominance which results in a better image quality than composite video. HDMI is fast becoming the must have connection as it is the basically a digital version of a scart connection and it has the advantage that it also carries audio.

Having a RS232 is basically a control connection to allow your projector to communicate with other devices such as electric screen.

Projector Throw Ratio Probably one of the most important specifications of any projector but most people don't know about it or don't know how to calculate this very simple formulae. If you are in mobile situation you might have limited space so knowing the throw is important. If you are installing then it is vital. If you know you screen size width say in metres (SS) then multiply the throw ratio (TR) and that will say how far away - distance (D) you need to place the projector. If there are two TR's then that is the zoom within that range SS x TR = D Eg screen size 2m , Throw Ratio 1.9 - 2.1 = 3.98m-4.2m Calculation 2 (SS) x 1.9 (TR) =3.98m away - distance the projectors needs to be from the screen 2 (SS) x 2.1 (TR) =4.2m away - distance the projectors needs to be from the screen Another example- a projector with a fixed lens- so must be placed at a exact distance SS x TR = D Eg screen size 2m , Throw Ratio 0.5 = 1m Calculation 2 (SS) x 0.5 (TR) 1m - distance the projectors needs to be from the screen So as you can see the lower the throw ratio (TR) the close or short the throw the projector is. Handy Hint 1: - If you have a tricky installation situation choose a projector that has a larger Throw Ratio range eg 1.4-2.1 which will give you greater flexibility Handy Hint 2: If you choose projector with an unusually large throw or short throw then bear in mind that any installation that you set up will mean that the next time you purchase a projector you will need to get a projector with the same throw ratio, and therefore maybe limit your choice in the future. If you want to know how big an image a certain projector will produce from a certain size then the calculation is still very simple Distance away from the screen (D) divided by Throw Ratio = Screen width (SS) Eg distance away 4m , Throw Ratio 1.5 - 1.8 = 2.22-2.6m image width or screen size Calculation 4 (D) / 1.8 (TR) =2.66m width of screen required 4 (D) / 1.5 (TR) =2.22m width of screen required So at 4m the image size will be between 2.22m and 2.6m An example- a projector with a fixed lens- so must be placed at a exact distance D/TR = SS E.g. distance away 4m , Throw Ratio 2 Calculation 4 (D) / 2 (TR) =2m width of screen required This means if you need a larger or smaller image then you have to move the projector as there isn't any zoom on the lens Every one of projecotr pages has a projector throw distance /screen size calculator too to make it easier for you

The last thing to mention is what is the future of projectors , certainly getting smaller for the mobile presenter, led technology has seen the emergence of the pico projectors or micro projectors which weigh less than 50g’s and Just Projectors believes that the low lumens output will be resolved within the next 5 years. Led projector with a combination of DLP technology has also seen the first lamp free projectors being made available, notably the Casio XJ-S range. They have a lamp life of 20,000 hours and without the mercury in any lamp is now the green option. 3D Projectors have always been available but now they are affordable. Using active technology DLP projectors can now show 3D using a single projector using the active shutter glasses and the prices are under £500 for a 3D solution. However a note of caution as yet 3D projectors only works with Sky TV if you purchase an Optoma 3d-xl adaptor.

Hopefully you would have found this article about projectors to be useful but please contact us at Just Projectors for all your projector needs.


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