Overhead proector

very useful tool before LCD projector.

1. OVERHEAD PROECTOR Presented By- SANJOG ZIMBAR

2. INDEX INTRODUCTION HISTORY MAJOR PARTS CONSTRUCTION WORKING ADVANTAGES DISADVANTAGES APPLICATION FUTURE DEVELOPMENT

3. HISTORY Created by FRENCH inventor “JULES DUBOSCH” in 1870 First used as cellphane roll over for police work Widely used I schools & bussiness in late 1950s and early 1960s A major manufacture in early period was the ‘3M” company But in 1953 “BUHL INDUSTRIES” became the leading contributor Very popular in 1990s as they were in almost every school in U.K. During world war 2 as a tool to train groups of survicemen .

4. INTORDUCTION Also called as “VIEWGRAPH” Basic but very reliable tool used to display images or written material onto a wall or screen . F0r audience and presenter can see properly. Consist of a large box containing a cooling fan & lamp, with a long arm extended above it.

5. MAJOR PARTS Lamp and Reflector- (with condensor ) Blower-(cooling Fan) Base Mirror- change the angle of the light Projection Stage- consist fresnel lens for magnifying & focusing image upword . Upper Section- 1. Focusing knob 2. mirror

6. CONSTRUCTION

7. WORKING With the help of focusing lens project light from an illuminated slide onto a projection screen where real image is formed . Depend upon size of transparencies used. Includes a mirror just after and before the focusing lens to fold optical system towards the horizontal. At the base the high intensity bulb with reflector is present which must be fan cooled. Condenser is most important part ,which is coollect all the light and concentrate on the fresnel lens.

8. working On the fresnel lens the transparencies is placed . also includes manual focusing mechanism which raise or lower the position of the focusing lens.

9. ADVANTAGES Simple technology Equipment Cost Transparencies Annotations

10. DISADVANTAGES Heat and Noise- fan create noise to dissipating heat created by the incandescend lamp Bulky and Heavy Equipment- difficult to carry for more than short distance . Projection Surface- required enough room Subject Matter- Display only which is write on the platform

11. APPLICATIONS Classrooms and Business conference rooms.

12. FUTURE DEVELOPMENT Now a days replacement for OHP , document cameras , computer projection system, and interactive whiteboard. Such system allow the presenter to project video directly from computer file using software such as microsoft ppt & libreoffice .

13. THANK Y0U….!