A projector can be used to project films on to a wall, giving you a great viewing experience. All you need to know about technology, light intensity and lifespan of the bulbs.
Flat-screen TVs have got bigger and bigger over the past few years. But if you really want a large picture, a projector is just the thing. They take up a lot less space than a TV set and can project videos onto large surfaces such as a screen or a white wall. A full HD projector can easily reach a screen-size of up to three metres and more!
Projectors — technologies
DLP. Digital Light Processing works with a semi-conductor that contains millions of tiny mirrors. Each corresponds to a pixel. The miniature mirrors are moved by electrical pulses up to 5000 times per second and reflect the projected light to a greater or lesser extent depending on the angle. The colours are generated through a colour wheel.
LCD. LCD stands for liquid crystal display. With this technology, the projected light is directed through a mini LCD display. The liquid crystals of the display let light through to a greater or lesser extent depending on voltage. State-of-the-art LCD projectors generally work with three displays, one for each primary colour (red, green and blue).
LCoS. Liquid Crystal on Silicon technology is similar to that of LCD projectors, the difference being that the displays reflect the projected light. This makes for a greater intensity of light.
LED. The projector works with DLP technology, but without a bulb. Projected light is generated by small light-emitting diodes (LEDs) that light up in the primary colours at high speed.
How do you read the device specifications?
Anyone wanting to purchase a projector is confronted with a myriad of technical terms. You must be able to get to grips with the most important information contained in the specifications in order to find the right device:
Luminous flux. The brightness of the projector is measured in Lumen (lm). We often refer to ANSI Lumen because the original standard comes from the American Nation Standards Institute. But this standard was withdrawn in 2003. To determine Lumen, measurements are carried out at nine points on the projection surface and an average is calculated. It is set in relation to the size of the projected surface and the result is the value of Lumen. A rule of thumb is at least 500 Lumen per square metre of projected surface.
Resolution. This specifies how many pixels are contained in the image generated by a projector. The most common is full HD resolution (1920 x 1080 pixels), but there are also projectors with 1024 x 768, 1280 x 800 and 1920 x 1200 pixels. Resolution is not related to the selected size of the projected surface. Models with 4K or ultra-HD resolution are still hard to find and come at a cost.
Contrast ratio. This is determined from the ratio of the maximum and minimum brightness of the image displayed by the projector. The higher it is, the higher the contrast and sharper the image.
Types of port. They dictate which sources can be connected to a projector. Common ones are HDMI, composite (RCA), VGA and S-Video. There are also models that can be connected via cable or WiFi to a network or can be played back directly from a memory medium via a USB port.
Nothing lasts forever: Projector bulbs
Bulbs are the material expendable parts of a projector (exception: LED devices). It generates light for the projection and therefore has to be powerful. The lifespan of projector bulbs depends on the model. For most this is between 2000 and 4000 hours. But we advise replacing the bulb if the quality of the image deteriorates and the colours appear to be less bright.
But replacement bulbs come at a cost: 100 to 200 euro. So when choosing your projector, find out about the lifespan of the bulb and how much it will cost to replace it.
Photo credits: fotolia/79640505/smuay
