Projector

How does a projector work?

A projector can generate an image to project onto a screen to display an enlarged version of the original. This makes it possible to show presentations and video footage to several people in a room or hall. The first system was created in 1939 and nowadays it is impossible to imagine offices and conference rooms without a projector.

Types of projectors

There are roughly two types of projectors: DLP and LCD. Both types of projector can deliver excellent images, but they also have some drawbacks. Let us explain the technology behind these two projectors:

LCD (Liquid Crystal Display): This type of projector contains a grid between the lamp and the projection lens, on which the three primary colours - red, blue and green - are located. The white light from the lamp is split into these three colours and a colour image is then developed by three separate LCD screens. The liquid crystal elements create an image with natural colours and smooth transitions. Clear reproduction is a big advantage of this technique while maintaining the filter and reduced sharpness are seen as a disadvantage.

DLP (Digital Light Processing): These projectors work with hundreds of thousands of tiny mirrors that project light onto the screen. Each mirror corresponds to a pixel and the light that falls on it is provided with the correct colour via a colour wheel. The three primary colours are part of this wheel and are projected onto the screen by the mirror through the lens. The speed of the mirror's changing determines the brightness of the display. This technique requires less space than the LCD projectors and can therefore be used well in smaller spaces. The sound of the mirrors is a bit more obvious, but the contrast on these systems is high. Digital cinemas use a complex implementation of this system.

Light output

The light output is indicated in ANSI lumens and a higher value means more light. The amount of light you need depends on the room in which you will be using the projector. If it's a bright room, it is advisable to purchase a projector with at least 2500 lumens. In a room with less light, a projector with fewer lumens may also suffice. In addition to the light available, the projection distance of the projector also plays a role in the light output. Finally, the projection surface should also be looked at, as a screen can handle the light better than a standard white wall.

Resolution

In addition to the light output, the sharpness of the projected image depends on the resolution of the selected projector. Modern projectors work with a resolution of at least 1280x720 pixels (HD ready) and the resolution of the image plays a decisive role in the final image quality, just like with cameras and TVs. In addition to the wide variety of Full HD projectors (1920x1080 pixels), 4K projectors which give a resolution of 3840X2160 pixels are becoming more popular. So always consider what you'll be using the projector for in advance, as well as the quality of the desired image.

Viewing distance and placement

The minimum viewing distance to the image determines the sharpness of the image, as well as the strain on your eyes. On average, 1.6x the width of the screen is used to determine the minimum viewing distance. At a higher resolution (Full HD / 4K), the multiplication factor decreases. The ideal placement of the projector in front of the screen differs for LCD and DLP projectors. LCD projectors should be hung with the centre parallel to the bottom or top edge of the screen or the wall. DLP projectors should be hung a bit lower than the bottom or higher than the top. Projection can always be optimised with the help of a keystone correction.

Functions

Projectors can have numerous functions that increase viewing pleasure. With the use of Wi-Fi you can, for example, project an image straight from a laptop or smartphone. Optical zoom is another nice feature. This allows the projection distance to easily be changed. With a lens shift, it is even possible to rotate the image while the projector simply remains in its fixed position. This function means that a good image can still be shown, even when the projector has a different orientation to the screen. Projectors nowadays have enough connections (HDMI, DVI) to improve both ease of use and sound performance.