Digital projectors (also known as “data projectors“) are common hardware output devices used mainly in business and educational settings, as well as for entertainment. Digital projectors project an image onto a screen or wall. Most of the specifications used for screens are used for digital projectors (resolution, contrast ratio, connections) and brightness, measured in lumens.
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The bulb of a projector is capable of projecting intense (very bright) white light. The intensity of this light is measured in lumens. Next time you are at the supermarket, have a look at the torches on sale: they will most likely have a rating in lumens — 200 to 300 lumens would be a pretty bright hand torch. Most data projectors sport light bulbs rated 2000 or more lumens! The bulbs are extremely expensive and consume a lot of electricity so it is best to switch the projector off when not in use.
Most projectors connect via HDMI these days. A slightly older projector will connect via VGA (most projectors will have VGA and HDMI ports). A VGA cable can only transmit video (picture) data whilst an HDMI cable can transmit video and audio (sound) data. HDMI is also capable of transmitting data at a far faster rate than VGA.
More advanced projectors will have the ability to connect wirelessly and/or using an Ethernet cable.
The resolution of a projector, which is mainly responsible for the quality (how clear the image is) of the image, is measured in the same manner as a screen: the number of pixels across by the number of pixels down, for example, 1920 x 1080.
Digital projectors are usually installed attached to the ceiling of the venue to avoid people from blocking the projected image. This is one of the reasons they have remote controls!
They must be installed within the correct recommended range (distance) from the screen they are to be projecting on. The more powerful the projector the further away from the screen and the larger the image is. Less powerfully projectors must be installed closer to the screen or the picture will lose definition (clarity).
- Can be viewed by a large group of people in a large venue.
- Not as bright as a monitor so the room must be darkened.
- Does not offer the same clarity as a high-resolution monitor (generally has a lower resolution than a high-end monitor).
- Not suited to a small venue (needs to be a minimum distance from the surface it is to be projected onto).
- Usually most effective when mounted from the ceiling which can make installation and maintenance complicated.
- The aspect ratio is not always suitable for certain uses, e.g. widescreen movies.
- Lower contrast ratio than a monitor