With the development of HDTV and the booming market for the DVD–successor, the Blu-Ray, more and more people are developing a taste for watching razor-sharp films. But if you want to view large, high-resolution images on a flat screen TV with a diagonal of 120 centimetres, you will quickly pay around 2000 euros for a device of this type. And this is exactly where the projectors come in!

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What are projectors?

Projectors are projectors that use various techniques to project an enlarged image onto a projection surface (wall, screen, etc.). A comparison with a slide show projector will probably help many, because it also throws (slide) images onto a wall.

The word "beamer" and the word "mobile phone" are not known abroad (with the exception of the Netherlands), but are a purely German invention. Apparently, the term goes back to the English verb "to beam" (= radiate). So if you tell an American that you have bought a new projector, he will assume that you have bought a stylish new BMW, since "projector" in English is colloquial for a BMW.

Why are projectors being used more and more frequently in home cinemas?

Of course, the development and introduction of high definition images was a leap of joy for many home theater fans. Finally, they could watch their movies in razor-sharp clarity on large flat-screen TVs and see every little detail. But at the latest by the 2006 World Cup in Germany, most home cinema fans – who were then also interested in football or at least the atmosphere – recognized that it could be much bigger. What is meant in this case is the image. At that time, many bars offered to broadcast the games on large screens. And what was used there? That's right, projector!

From then on, the starting gun was fired for the purchase of projectors and screens for those for whom their full HD flat screen television with a screen diagonal of 130 centimeters was too small.

What advantages do projectors offer in general?

The biggest advantage is obvious: films can be viewed in an almost cinema-like size in the four walls of your home. Current devices make it possible to project television and video images in HD format onto the wall, even outside of the darkened basement home cinema – with excellent contrasts and a screen diagonal that is (almost) only limited by the illuminated wall. And against a three meter wide, high-resolution screen, even the 50-inch flat-screen TVs look very small!

Devices that are ideal for creating a party atmosphere at sports events are now available for around 300 euros. You simply clear a sufficiently large wall, set up the projector at a suitable distance and place a laptop next to it for the input signal DVB-T-Stick. After the event, the projector quickly disappears back into the closet, as does the laptop. Movie buffs get shivers down their spines at first when they see the rather dull picture of the cheap devices - but in the end it's fun to watch a live broadcast of this size.

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What types of projectors are there and what are their advantages and disadvantages?

As is the case with normal television sets, which now differ in terms of the various techniques used to display the image (LCD, Plasma, Laser, LED, tube), there are also different models of projectors, which are often specialized in a single area of ​​application. So that you can get a small overview in advance, the most common projection techniques and their advantages and disadvantages are briefly explained here.

LCD projector:

In principle, liquid crystal projectors work in the same way as slide projectors. However, instead of a slide, they have small, transparent liquid crystal elements. The technology is explained relatively simply: a white light is split into the three primary colors with a prism and sent through three small LCD displays. A further prism then composes a color image from this. Particularly high-quality models use three different prisms – one for each of the three primary colors (red, green, blue). In the devices with only one prism, the primary colors are displayed next to each other, which leads to a coarser image impression.

In general, the LCD devices are characterized by their low price, their relatively quiet operating noise, their compact size and the good readability of texts. LCD models are less brilliant when it comes to film playback, because there are often streaking effects and poor black value display (black is displayed more as gray) as well as the so-called LCD memory effect, which causes burn-in, e.g. B. denoted by station logos for too long bright lighting. Therefore, these devices are more suitable for beginners!

DLP projector:

DLP–Beamers (Digital Light Processing) project the image using many small mirrors. The light is split into the three primary colors by a color filter wheel, which are then projected onto the screen one after the other. The color mixing is done by the human eye. For some people, this results in the so-called rainbow effect when viewing moving images, ie if the viewer's eye movement is not synchronous with the movement of the object on the screen, the three primary colors can flash briefly.

Beamer models that use DLP technology have good black values, response times and depth of field as well as high luminosity. In contrast to this is the still relatively high price, occasionally very loud fans, pale color reproduction, problems with the display of gray tones and the already mentioned rainbow effect. However, the problem of pale color reproduction only occurs with 1-chip DLP projectors. If you use models that have three chips, you can turn the disadvantage into an advantage.

LED projector:

LED projectors (Light Emitting Diode) use light-emitting diodes as the light source. Light-emitting diodes (LEDs) are very small (approx. 1cm) and are used not only in projectors but also in newer traffic lights, car tail lights or in combination as living room lights. As with DLP projectors, a DLP element is also used here for imaging.

LED projectors require little power and can therefore also be operated with a rechargeable battery, which supplies the device with power for up to three hours. Due to the hardly any heat generation due to high energy efficiency, LED projectors require little cooling, which makes the devices comparatively very handy. The light-emitting diode as a light source itself lasts up to 20.000 hours (normal projector lamps approx. 6.000 hours), but gets darker and darker with age. Disadvantages of these projectors are the insufficient luminosity, which is just enough for a picture with a diagonal of one meter in a very darkened room, as well as the currently still low Resolution of 800×600 pixels. However, Texas Instruments, among others, has models with a full HD resolution of 2009×1920 for mid-1080 pixel announced.

LCoS projector:

The Liquid Crystal on Silicon technique is still quite new on the market. Just like with LCD projectors, liquid crystal panels are used here. But instead of shining through them like an LCD projector, there is a mirror directly behind the crystals, so that the projection optics are more like those of a DLP projector.

LCOS–Beamers are offered in a compact design and deliver sharp images. However, this requires an input signal with a fixed resolution. In addition, there may be a slight dragging of the image and the burn-in of station logos (LCD memory effect) or similar.

Please note that not all manufacturers use the term LCoS for their projectors. At JVC this technology is called D-ILA technology, at Sony it is called SXRD. In the meantime, the first new mobile phones on the Japanese mobile phone market are also using LCoS for their displays.

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Purchasing Advisor - What to look out for!

Before the purchase

Before you run to the nearest electronics store (or look up an online retailer) and buy a suitable projector, you still have to give a lot of thought to the location of the projector. This may surprise you, but there are basic things to consider. The reason for this is: The desired image size and the required distance from the projector to the screen are defined by the optics of the device. This can only be exchanged for very high-priced models.

The aspect ratio (e.g. 16:9) and the distance from the viewer’s seat are the decisive factors for the size of the picture diagonal.
As a rule of thumb, you can remember: The first row of viewers should be seated twice as far from the screen as the picture is wide.
As a result, unless you enjoy moving furniture, you rarely come across canvases that are more than two meters wide in living rooms. Movie buffs should also consider the 7.1 system, which still needs enough space.

But what good is the best screen if it doesn't fit into the room at all? Key word: image height. It is not uncommon for a television set to be set up around which the surround system is placed. This means that the space above the TV edge is up to the blanket, minus approx. ten centimeters for the screen frame as the maximum picture height. If you are planning to use a roll-out screen, there is space for the box under the blanket from the calculation result.

Once we have found the maximum image height, we can use the aspect ratio – as an example here 16:9 – to calculate the maximum image width that a suitable screen may have. So you now divide the image height by nine and multiply it by 16. Sample calculation: Your room is 280 centimeters high, your television ends at 125 centimeters from the floor. After deducting the frame width (left and right ten centimeters each), this results in a maximum image width of 255 centimeters. (280 centimeters minus 125 centimeters divided by 9 multiplied by 16 minus 10 centimeters left minus 10 centimeters right).

If, according to Adam Riese and Eva Zwerg, this value is suddenly greater than half the distance between the seats, you should rather reduce the picture height rather than risk an uncomfortably large picture impression. Based on our calculation example and the above rule of thumb, your sofa would have to be placed a little more than five meters from the screen. You can easily find out the image diagonal with a pocket calculator. Take the square root of width squared plus height squared.

Once you have made the screen and seat preparations, you should consider where you want to place your projector. If you prefer ceiling mounting, you need an appropriate bracket, which in most cases has four screws in the blanket screwed and fixed to the projector with another four screws. Since the projector is attached "overhead", speak with the little feet blanket, check when purchasing whether your device has the ability to display the image rotated horizontally. When placing it in a cupboard or shelf, make sure that the exhaust air from the cooler can escape unhindered and place it at least one meter away from where you are sitting so that the possibly loud fan noise does not get on your mind at some point. In any case, for the sake of the image quality, you should set up the device in the middle of the screen, because every image adjustment on the projector not only affects the image quality, but also the uniformity of the illumination - even with models with lens shift.

Once the installation question has been solved, you only have to think about the cabling. Because you have to lay at least one power and signal cable at every installation site. The ideal solution for this is, of course, concealed installation.

Usage

Movie or TV? A valid question to ask yourself! If you mainly want to watch DVDs or Blu-Rays with your device, you have to look out for a projector that image format 16:9 supported to reduce the black bars at the top and bottom of the picture. A 4:3 projector that supports 16:9 switching is sufficient for normal TV programming.

However, since you often turn on the television throughout the day, you also have to pay attention to the luminosity. If you only want to watch films in the evening, an entry-level device with a lower brightness is sufficient, since it is dark in the evening anyway. However, if you need the projector for the TV program in the afternoon, e.g. B. for football broadcasts, the darkening alone for this occasion is a bit cumbersome in the long run. Therefore, your device needs a correspondingly high luminosity and high contrast for such an occasion.

The benchmark for the luminosity and thus the brightness of the image are the ANSI lumens, with which the luminosity on the projection surface is measured. For those who like to use the projector in darkened rooms (cellars or similar), a luminosity of approx. 1.000 ANSI lumens will usually be sufficient - devices that can be used in daylight, on the other hand, should have at least 2.000 ANSI lumens and contrast values ​​from 2000:1 ( Home cinema projectors require at least 1000:1). For comparison: A 100 watt light bulb generates a luminosity of 1350 ANSI lumens on a screen.

But not only the intended use is decisive for the required luminosity, but also the size of the room and the distance to the screen. The further away the projector is from the screen, the higher the luminosity must be.

Resolution

For DVD playback you need a resolution of 1280×720 pixels – the so-called WXGA standard. A resolution of 800×600 pixels is unsuitable and the XGA variant with 1024×768 pixels corresponds to the 4:3 format, which is why you can use such a model if you mainly want to watch TV with your projector. However, please do not think that an XGA device is HD-capable because it shows 768 picture lines, because these devices only have 1024 horizontal picture lines – which is not enough for HD (HD-Ready corresponds to 1280×720 pixels).

Regardless of whether it's film or television, your future device should at least be "HD ready". Because according to the plans of ProSiebenSat1 Media AG, the channels are to go on the air in high definition as early as 2010 (as of April 2009). But especially for those who already own a Blu-Ray player, the projector must have an HD Ready or even better Full HD logo. Because if the projector supports the same resolution as the films on the Blu-Ray disc, namely 1920×1080 pixels, you will be able to see every detail in your favorite film in the future. Even if your film has not yet appeared on a Blu-Ray disc, you will benefit from the high resolution of the projector, because the latest DVD and Blu-Ray players support scaling of the normal DVD image (576 vertical image lines) to 1080 vertical image lines (a so-called "upscaling").

A full HD projector has a resolution of 1920×1080 pixels. Information from the manufacturer can also 1080 or 1080p be. 1080i corresponds to playback in interlaced scanning, 1080p of full-screen playback. For more information on Full HD, see the appropriate Home Theater Knowledge Report!

picture quality

Apart from the already mentioned aspects of the purpose of use, the associated luminosity and the resolution, the contrast, black levels and color representation of the various projection technologies are explicitly discussed here again.

It should be known that contrast is defined as the distinction between light and dark tones. But how much contrast is useful? When a white field is displayed next to a black field, the eye cannot distinguish whether the contrast value is 1000:1 or 5000:1. There are also limits to maximum contrast in perception. However, it would be wrong to conclude from this that a contrast of more than 1000:1 is pointless, as is often claimed. Because the reason for this is simple: In a correspondingly dark environment, there is not only the contrast within the image, but also the difference to the black environment - this becomes particularly clear in a planetarium. But even in your own home cinema, an almost infinite contrast value is worth striving for, because the image boundaries are no longer visible with total black. Because at the edges there is not maximum white against black, but the residual light against absolute darkness. And here the eye still perceives differences.
In addition, the higher the contrast ratio, the brighter the colors appear. Therefore, as with any other home cinema device, the following applies to you: compare – if possible also in darkened sales rooms. In addition, not only the projector but also the screen contributes a large part to the high-contrast image. That's why not only home cinema enthusiasts should think about their wallets, but also those who only occasionally want to watch an old DVD in the evening, because even the best projector image loses a lot of light intensity and color on a white woodchip wallpaper!

As already mentioned in the first section of the report, the different types of projection have their individual advantages and disadvantages. LCD projectors, for example, still have problems with film playback, because smearing and burn-in effects as well as a barely sufficient black level display make these devices only interesting for business purposes and for beginners (also because of their low price!).

DLP projectors, on the other hand, excel in film playback with optimal depth of focus, luminosity and black levels. The pale color reproduction can be compensated for by purchasing a 3-chip DLP model. The only drawback is the still relatively high price and the sometimes loud fan.

The newer LED projectors are very compact, offer battery operation due to their low power consumption and have three times the lamp life. The disadvantage here, however, is that the film playback is not yet optimal and the relatively low luminosity, so that such devices prefer very dark rooms.

LCoS projectors work in a similar way to LCD devices, deliver sharp images and are offered in a compact design. Unfortunately, these models have almost the same disadvantages as their LCD half brothers: streaking and burn-in effects!

volume

It is also important to note the noise level of the device, because there are significant differences. Above all, the LCD and DLP models equipped with a large fan cause background noise of up to 40 dB! For comparison: a quiet conversation is around 30 dB. And the blowing of the fan can be annoying, especially in quiet scenes. Therefore, you should not only make sure that the device is set up sufficiently far away from your seat (see section "Before you buy"), but also that it operates relatively quietly - a value of 30 dB is still OK - however, a value that would be desirable which is below!

When buying, in addition to the specification of the volume, the position of the fan outlet in the case should also be considered - because that's where it is loudest. If there aren't many options for placing the projector in the living room, this can be a crucial detail!

Also worth mentioning is the connection between luminosity and fan. Because the stronger the luminosity, the hotter the lamp gets and the more powerful the fan has to work. It also consumes more power and becomes loud (increasing speed).

follow-up costs

Regardless of the type of projection, all projectors have one disadvantage in common: they age! After a few thousand hours (LCD/DLP approx. 4.000 hours, LED 20.000 hours), the lamps have to be replaced, which costs between 70 and 700 euros depending on the device. For example, if your projector lamp has a lifespan of 2.000 hours, this corresponds to a lifespan of one year with daily use of 5,5 hours!

Some projector models have an eco or whisper mode, which not only reduces the fan speed but also protects the lamp. Of course, a lamp that burns for 4000 hours costs less in the long run than one that burns for 2000 hours.

But in order to keep your costs as low as possible, you too can help to protect your projector lamp.

• Avoid using the device for short periods of time. If you e.g. For example, if you just want to watch the news, you better use your TV. Switching on and off causes the lamp to wear out a lot!

• After a film, first switch your projector to standby mode. Then the fan cools the lamp for a while. You should only switch off the device completely at the mains switch when the fan switches off.

• Operate the projector in the eco or whisper mode mentioned above. According to the manufacturer, this increases the life of the lamp by up to 50 percent! You can often find the eco or whisper mode in the projector menu under the items "Eco", "Silent" or "Cinema".

Connections

As with flat screen televisions, you will achieve the best picture results if your projector has at least one HDMI- or DVI-Interface offers, as these transport the digital data without loss of quality. Please note, however, that with an HDMI-capable projector you also have a Receiver Your property should name that Copy protection HDCP decrypted, otherwise you can look forward to a black picture during DVD and Blu-Ray playback (only an advantage for members of an occult sect)! For analog connections, connect the projector via a YUV-Video input on. S-Video connections are not recommended as the signal quality deteriorates noticeably here. The video images often work when Connection using the Composite-Connection flat and fuzzy, so test this type of connection in advance and switch to YUV or HDMI if necessary. However, please note: Since projectors work digitally internally, analog input signals are first digitized, which can lead to a loss of quality. If your PC transmits signals from time to time, the graphics card output (VGA or DVI) can be used.

To get an overview of the different cable types, you can also take a look at the report "HiFi and home cinema cables“ in the home cinema – throw knowledge!

Other

Most projectors still have some nice gimmicks on board, such as a zoom lens. This allows you to enlarge or reduce the image to fit the canvas. The larger the zoom range, the more leeway you have for the distance between the projector and the screen. Without a zoom lens, you have to move a projector back and forth until the image fills the screen exactly according to our calculation example.

A newer feature is the image offset, also called lens shift. If you do not have the space to place your projector in the middle of the screen as described in the "Before you buy" section, the image may look distorted. Lens shift is a mechanism that adjusts the lens and straightens the image again. Ideally, the projector can adjust the lens horizontally and vertically. Important note at this point: This mechanism works without loss of quality!

Keystone correction compensates for distorted images; the image is reduced in size. If a projector beams the image at an angle onto a screen, the image is distorted. In order to compensate for these image errors, many projectors offer trapezoidal correction in their menus. Disadvantages here: decreasing image sharpness and grey, unevenly wide borders at the edges of the image.

All models are actually able to save the settings, for example starting in Eco mode or the overhead display when mounted on the ceiling.

As part of the green IT offensive of many manufacturers of entertainment electronics, you should also pay attention to the power consumption (especially in standby mode)!

projection

Ideally, the surface that you want to "beam" should be a screen. But canvas is not just canvas.

One of the most important points in addition to the right size, which you have already found out using our example calculation, is a black border on the screen, which makes the images appear even more contrasting.
For fixed mounting under the blanket or on the wall you can use roller screens. Manual roller blind screens are already available for less than 100 euros. Models with an electric motor cost more than 200 euros in most cases. Roller blind screens often only have a thin and therefore slightly wavy cloth, which worsens the picture impression. Tripod screens can be set up quickly for a football game and then disappear again. However, they are often wavy (tip: leave them hanging for a long time) and there is also the realignment of the projector, since you do not set up the screen with millimeter precision every time.
If you are planning your own home cinema or if you have an understanding wife, you can also use a fixed frame screen that always hangs perfectly stretched in the same place, but is always visible without any tricks.

You also have to adapt the screen to the image format of the projector - i.e. a more square screen for 4:3 models or a more rectangular one for 16:9 playback.

But how do you recognize a good canvas from the diverse selection? In addition to the black frame and the taut cloth, the gain factor plays an important role. This indicates how bright the image appears on the screen when you are sitting directly in front of it. Values ​​between 0,8 and 1,2 are optimal for your own home cinema.

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The commissioning

If everything went smoothly, you can now watch films or watch TV with your projector. But for many it is not that easy, since the manuals are mostly written in technical jargon.

• If you have a television receiver for satellite or digital television (regardless of whether it is cable or antenna), connect your projector to the video output (yellow) there. Most TV receivers have one Scartoutput, but only a few projectors have a scart input. That's why you often need an appropriate one Adapter. Then connect the audio outputs of the receiver to your system

• If you use analogue television via cable or antenna, you can connect a video output on your television to the projector. However, the television must remain switched on during playback with the projector. Therefore set the picture there to the lowest brightness level. The Ton either your television or, with the appropriate wiring, your system.

• If you have a video or DVD recorder, you can use it as a TV receiver and connect your projector to a video output there. You then switch between the television programs with the remote control of the video recorder.

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Tip

You can often eliminate jerky pictures by connecting a DVD player with full-screen playback (progressive scan). If the projector is using YUV cameras, switch the YUV output to "Progressive Scan" in the player menu. With a digital connection (HDMI or DVI), select the picture format “576p” or “720p” (576 or 720 vertical lines in full screen) for DVD playback. Another advantage of this setting: Depending on the projector model, the image appears a little sharper.

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Here you get a small overview of the prices of the current projectors (as of early 2009):

notification procedure	image format	Resolution in pixels	Price
LCD	4:3	640 × 480	from approx. 150 euros
LCD	4:3	800 × 600	from approx. 250 euros
LCD	4:3	1024 × 768	from approx. 350 euros
LCD	16:9	964 × 544	from approx. 600 euros
LCD	16:9	1280 × 720	from approx. 500 euros
LCD	16:9	1920 × 1080	from approx. 1000 euros
DLP	16:9	854 × 480	from approx. 300 euros
DLP	4:3	800 × 600	from approx. 350 euros
DLP	4:3	1024 × 768	from approx. 450 euros