 |
 Projection Tv - Projection TV technology can create large screen sizes at a reasonable price.
|
|
|
|
|
Diy Projection Tv. In its basic and most simple form, you are just placing a magnifying glass in
front of your TV to project the image onto a wall.
|
DIY Projection TV
The CRT TV - fresnel lens type DIY projector:
In its basic and most simple form, you are just placing a magnifying
glass in front of your TV to project the image onto a wall. In the
process, you have to direct all light emitted by your TV onto the
screen through your lens - otherwise the whole process fails.
The best way to build a projection tv based on this principle is to
construct two 'open-ended' cardboard or thin plywood boxes - one
designed slightly smaller than the other such that the smaller box
can slide into the other.
The larger box should be designed to house a TV or computer monitor.
A projection lens is then fixed on the front of the smaller box and
the two are inserted into each other. Sliding the smaller box in or
out of the bigger one will help focus the image onto the screen.
This two-box set-up allows for ease of focusing and image size
adjustment.
Usually, the lens used in the process is a fresnel lens. While it is
possible to use any double convex lens (magnifying lens), yet due to
the curved nature of these lenses, the projected image will be
heavily distorted around the edges.
A fresnel lens is unique in that it is completely flat - it takes the
curve of a lens and reduces it to a flat shape by sectioning the
lens into a large number of concentric rings. Hence you get no real
distortion or bending of the image because every part of the lens
projects the whole image. For additional information on lenses,
click here.
The inside of the boxes is usually sprayed with black matt pant to
avoid undesirable effects as a result of internal reflections.
Focusing and projected image size are correlated - both are dependent
on the lens-to-Tv (or monitor distance) and the
lens-to-projection-screen distance.
Setting up this type of projector can be a timely process as
adjustments have to be made in small steps at a time to eventually
clearly focus your projector and adjust the image size.
This is all that it takes to build a projection tv using a fresnel
lens. This type of DIY projection tv unit works 'fine' as long as
you accept the design limitations:
|
|
|
|
Diy Projection Screen Tv
|
|
TV Sets
Back
Site Contents Map
Page Index A-Z
Site written by Gemma Littlemore