projectors

projectors

The projectors are used to project the transparent materal.

we generally make use of the following thre types of projectors:

1.slide cum filmstrp projector

2.Overhead projector

3.Opaque projector

Slide cum filmstrp projector

As the name suggests, this type of projector are helpful in projecting slides as well as flimstrips on the screen and thus making it possible to view,in an enlarged from, the graphics like picture,charts,diagrams,photographs,maps,cartoons,posters,graphs and timelines related to the subject.

The basic design of a slide-cum-filmstrip projector is same as that of lantern slide projector.

uses.......

fore the use of this of type of projectors, teacher in charge should try to gain competency in this task of handing the seitches meant for the operation of vairous functions of the equipment along with the certain needed precaution.After that he can insert the desired filmstrips or slides one by one at the proper time of their instructional use and keep them on the screen as long as it is necessary.

overhead projector

The overdead projector,although having similar optical elements, repersents a lot of improvement over magic lantern, slide, and film projector.

uses.......

1.It contains an area of vertical projection besides the straight horizontal path of light available with the usual projectors.The path of the light rays is again changed to a horizontal one by a mirror placed at 45 angle.

2.It provides for the focusing of the image on the screen by vertical  movements foe the projection head(containing the objective lens and mirrior).

3.there is a provision of a constant flow of air past the lamp by a cooling fan in the base of the projector.

Advantags

1.Since the slides in this projector are placed on

top of the

glass prture, there is no difficulty in changing the slide.Moreover, the teacher may also see the slides exactly as the students do and thus is able to integrate his comments and teaching with wate is being projected on the screen.

2.The operational task of this projector also does not invole any difficulty.It simply requires turning of the power switch,placing the slide on the projection platfrom and focusing the image on the screen.

OPAQUE PROJECTOR

the slide-film projector and overhead projector discussed so far can only be used to the project the transparent material.

The opaque material,like picture,diagram and specimen can not be projected by these projectors.

The third type of projectors, namely opaque projec tor do away with this difficulty.

DISOPAQUE IGN AND  WORKING OF AN  PROJEC TOR

In opaque projector the principle of reflected light is used for the projection rather than the direct light transmission, as shown in thev diagram in Figure 3.4.

The projection area in the opaque projector lies at the base of the projector.

  1.Any material, whether transparent or non-transparent, related to instruction can be properly projected on the screenfor viewing by the entire class with the help of this projector.

2.IN this projector it is not essential to prepare slides of the graphic material for its visual display on the screen.material like photographs, picture, graphs, diagrams.

3.The most striking use of the opaque projector lies in the fact that it needs almost no arrangement or preparation with regard to mounting for the dispiay of graphic material on the screen.

4.All types of three-dimensional aid material such as actual objects,specimen, models and mock-ups can be projected on the screen by placing them on the platfrom of this equipment.

5.The projection carried out through this projecttor can prove quite helpful in the study of various topics related to the subject areas of history, geography and other social as well as environmental and natural sciencess.

6.A unique advantage of the opaque projector lies in the factthat it can be utilized with care for enlarging and other illustrative material to a chalkboard or to the large sheet of chart paper placed on the screen for tracung.