How to choose a projector for classroom
January 3, 2018 by admin in Gadgets

How to choose a projector for classroom

Projectors are really an essential equipment nowadays. People are using projectors in every area of daily life. Teachers are using it to teach the students in a better way. A meeting cannot be conducted perfectly without using a projector. So, you must know what is a projector, how does it work and how can you choose a good projector. Let’s learn about the uses of classroom projectors and how to choose a classroom projector.

First, an essential element is the width and height of the projection surface, so that all students can see the contents, even those that are further away. Therefore, the greater the distance between the projection surface and the furthest student, the larger the viewing area should be. Recently it has been identified that the projection in 4: 3 formats is not the most appropriate, so it tends to adopt larger formats, such as 16: 9 or panoramic. For this, it is convenient to perform several tests depending on the number of rows in each class.

When we have decided on the appropriate size of projection, we must measure the minimum brightness that is necessary for the classroom. It must be emphasized that more or less brightness does not make the projector better or worse, what makes it ideal is that it is adapted to the real needs of the classroom. Many people think wrong – that the brightness depends on the distance to which the projector is installed. This is not correct since the light output depends only on the area where the emitted light is dissipated. The brightness is measured in ANSI Lumens (ANSILm) and it is an international unit of measurement.

What you should check before buying a projector


Another important point is the contrast. It is a data that most manufacturers supply and is related to the quality with which the colors differ, considering the combination of them and the resolution of the image. This data is given by the relation between the projection of the white and the residual that leaves the light when it emits the black color. For example, a ratio of 500: 1 means that for every 500 ANSILm of brightness when the projector delivers the target, it leaves 1 ANSILm of light residual when it makes black.

In addition, the residual light must be added to the ambient light of the classroom that has natural light and artificial light. With this information, we will not know how to carry out the integration of an audiovisual system, but at least we can identify what they want to sell us and, above all, if the one who offers it has the minimum knowledge to face an installation of this type.


On the other hand, another data that the manufacturer usually provides us is the resolution, which refers to the number of points that make up the image. One of the lowest resolutions currently is the SVGA, which forms an image of 480,000 points or pixels (800 horizontal x 600 vertical). In contrast, the XGA resolution has 786,432 points (1024 × 768), which also makes the product more expensive. Certainly, the difference between one resolution and another is important when what is going to be projected contains very small letters or when the projected image exceeds 3 meters. For other uses, a high resolution would not be necessary.

Types of lamps

The useful life of a lamp is a key feature for the choice of the classroom projector since it is subjected to high temperatures for a long period of time and its replacement is usually expensive. The reason for the high cost of lamps is that when you have to change it, after 3,000 or 4,000 hours of use (about 4 years), the projector model will be discontinued, and the price of the lamp replacement will be much more expensive, so It is recommended to acquire brands of projectors that include replacement lamp.

There is another lamp technology that does not use mercury, which is eco-friendlier, and it uses a hybrid combination of laser and LED. The duration of the lamp is 20,000 hours (almost 7 times more than a mercury lamp), although this technology is somewhat more expensive.


There are 2 projection technologies: DLP and LCD. DLP stands for Digital Light Processing and LCD Liquid Crystal Display. DLP achieves an excellent image and does not use filters, thus reducing projector maintenance. The LCD projectors incorporate a filter that has to be changed with a certain frequency (depending on the dust in the classroom).


Some years ago, the projectors began to be used in the classrooms, with their easels and laptops. Until then, the teacher was behind the projector to give the class, but with the most recent introduction, the interactive whiteboard (PDi) has to be placed directly in front of the projection, so that in many occasions it receives directly the glow of the powerful Focus on the face. On the other hand, when turning to write in the PDI the focus itself generates an uncomfortable shadow that covers part of the contents. Who has not suffered this with their PDI if they work with a long-range projector?

To solve this problem, ensure correct visibility, avoid visual fatigue and reduce uncomfortable shadows, projector manufacturers have resorted to new solutions to reduce the projection distance between the projector itself and the PDI. Thus short and ultra-short range projectors appear. While long-range projectors are usually installed at a distance of 2 to 4 meters from the blackboard, these new, which incorporate wide-angle lenses or mirrors that open the beam of light, are installed at a much lower distance (between 0 ’60 and 1 m) and offer the same projection surface at a very close range.

These new models are usually installed on arms or extensible metal brackets that come out of the wall (unlike long-range projectors that are installed in the ceiling) and some models even include speakers of a certain power (10 to 15 w). In addition, with these projectors integrated into the new mobile supports for PDi (which are structures on wheels) are obtained integral solutions of great versatility, especially when you want to use it also in other classrooms of the center. If you are thinking about acquiring new projectors for your center, you may have to contemplate the usefulness of short and ultra-short-range projectors, since they will be very useful for use with PDIs.

Author Bio: Andrew Wyatt is the founder of Bestolin is a blog where Andrew and his team writes about different gadgets, scientific research and projects.

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