Advice on choosing and buying a projector
Where will the projector be placed?
The room size, the width and length of the room, the size of the audience, the distance between the screen and the projector and where the projector will be placed are all important parameters to consider when choosing a projector.
How large is the room where the projector will be used and how large is the distance between the screen and the person in the audience placed furthest from the screen?
A big room with a large distance between the screen and the last row of the audience requires a projector with high light output to produce a picture large enough to be seen. TCO certified projectors are certified to provide an optimal picture quality on a specific area, TCO Image Size i.e A TCO Image Size of 3 m2 is equal to a diagonal picture size of 100 inches.
In large lecture halls it is possible to use two projectors in parallel to double the light output.
If there is a chance that the person presenting will be between the projector and the projected image then choose a short throw projector. A short throw projector is equipped with a lens that projects a large image at a short distance.
The diagrams below give you an idea of what is necessary.
Office Projectors 4:3 ratio with ambient light of 100 lux
Video Projectors 4:3 ratio with ambient light of 20 lux
The light level in the room is an important factor to consider when choosing a projector
A bright room requires a projector with higher light output compared to what is required in a dark room. How much more depends on the ambient lighting condition.
In the table below (video projector) you get an idea of how much more light output is required in bright lighting conditions to maintain the same TCO Image Size.
| Ambient light level |
How TCO Image Size is affected |
Increase the light output to maintain same TCO Image Size |
Dark
(20 lux) |
100% |
0 |
Low light
(60 lux) |
88% |
+14% |
Moderate light
(100 lux) |
78% |
+28% |
Bright light
(200 lux) |
50% |
+100% |
Which projector technology suits my needs?
There are different technology types
The most common are DLP (Digital Light Processing) and LCD (Liquid Crystal Display).
Additional technology is LCoS (Liquid Crystal on Silicon). The technical development for DLP and LCD projectors with LED (Light Emitting Diods) based light is rapid.
Many manufacturers have short throw projectors which is a projector (regardless of technology) equipped with a lens that projects a large image on a screen placed a short distance from the projector.
DLP (Digital Light Processing)
In a DLP projector, light from the projector's lamp is directed onto the reflective surface of the DLP chip which is made up of thousands of tiny mirrors. Each mirror represents a single pixel. The mirrors wobble back and forth, directing light either into the lens path to turn the pixel on, or away from the lens path to turn it off.
In high quality DLP projectors, there are three separate DLP chips, one each for the red, green, and blue channels. However, in less advanced DLP projectors there is only one chip. In order to define color, there is a color wheel that consists of red, green, blue, and sometimes white (clear) filters. Projectors with a color wheel with upto six colors, adding the accent colors of cyan, magenta and yellow are entering the market in order to increase the color quality. This wheel spins between the lamp and the DLP chip and alternates the color of the light hitting the chip from red to green to blue. The mirrors tilt away from or into the lens path based upon how much of each color is required for each pixel at any given moment in time. This activity modulates the light and produces the image that is projected onto the screen.
Pros with DLP projectors:
- High light output
- Long life time
Cons with DLP projectors:
- A rainbow effect can occur
LCD (liquid crystal display)
LCD projectors usually contain three separate LCD glass panels, one each for red, green, and blue components of the image signal being fed into the projector. As light passes through the LCD panels, individual pixels ("picture elements") can be opened to allow light to pass or closed to block the light, as if each little pixel were fitted with a Venetian blind. This activity modulates the light and produces the image that is projected onto the screen.
Pros with LCD projectors:
- Bright colors and high resolution
Cons with LCD projectors:
- The filter needs regular cleaning
- After some time of usage the LCD panels give a yellowish picture
- Shorter life time and less deep blacks than DLP
LCoS (Liquid Crystal on Silicon)
LCoS combines the DLP and LCD technologies. 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 DLP projectors.
Pros with LCoS technology:
- Very high resolution
Cons with LCoS technology:
- Expensive
Consider the following when choosing screen
The screen is another important factor for an excellent picture experience.
Take the following into consideration when choosing a screen for your projector:
You need to consider what picture size, TCO Image Size, you want to have and what aspect ratio the pictures will have.
What type of screen do you want?
Here are some example of the choices:
- A frame mounted screen fixed to the wall
- A ceiling mounted screen that is possible to pull up and down manually or by a motor
- A Portable screen with a stand
Choose a screen there the light reflecting, gain, features fulfill your needs
Gain is the screens ability to reflect light in a specific angle to the audience.
A screen can have a gain range from 0.8 and onwards. A screen with gain factor 1.0, also named no gain, reflects the light evenly in all directions. This type of screen is preferable in cinemas with a large audience. The higher a gain-factor the more light will be reflected from the middle of the screen and less from the sides.
Maintaining your screen
Screens get dirty and dusty and regular maintenance is preferable for a good picture experience.
More to consider when bying a projector
If you want to have a portable projector check the total weight of projector, cable and bag. Some projectors are equipped with a handle to facilitate transport.
To minimize environmental influence when using a projector have the following in mind:
Choose a projector with low energy consumption.
Use the ECO mode for lower energy consumption and increase life time of lamp.
Maintain the projector according to manufacturers’ specification.
Find out more:
Advice on choosing and buying a projector
Advice on using a projector
Advice on disposing of an old projector
Advantages of a TCO Certified projector
