Fisheries Extension Education (2+1)

Components of the Projectors

1. Bulb – There are two types of bulbs are available. One is screen type and another one is pin type. The volt and watt is another capacity of the bulb that should be considered in fixing for the reelection purpose. The watt is the capacity of bulb i.e., 100, 300, 500 and 1000 w, where as volt is the quantity of current flow i.e., 120, 220 and 440 v. It may vary according to the type of the projector.

2. Reflecting Mirror – It is used in direct and indirect projection system to reflect the light from the projection lamp towards the condenser lens and object being projected. The reflector starts to scale or turn a dark colour, it would be advisable to replace it, or in the case of a large mirror such as that used in an opaque projector to have it resurfaced.

3. Lenses - The lenses are broken, improperly mounted or are allowed to get out of alignment. As a result poor pictures are projected on the screen. The condenser lens is located near the projection bulb, it is necessarily subject to considerable heat and often cracks or bakes.

Some of projectors equipped with an additional glass disc called a heat filter, which is designed to cut down the intensity of heat striking the film material. The heat material does not decrease the amount of illumination striking on the screen.

The purpose of the condenser lenses is to make the light rays to fall on the object uniformly. The objective lens focuses the picture as it is projected on the screen. Most of the objective lens is coated. A coated lens is treated with a special chemical that reduces reflection within the lens and allows more light to pass through the lens to the screen.

4. Screen - A good screen is essential for successful projection of the picture viewing. Some screens are wide angles, some are narrow angle and some another is made for rear projection. Screens should be selected with great care, depending upon the projection job and should be tried in the rooms where they will be used. The followings are some type of screens: 1. The beaded screen, 2. The Mattel screen, 3. The aluminum or silver screen, 4. Lenticular screen, 5. The translucent screen, 6. Plastic screen.