OK guys, I need you input on this.

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I have started my lcd rear projection project using a Sony KP-46c70 46" big screen tv.

I am using the original lens setup in order to keep the angles correct to hit the screen.

The problem i am having is i think with the light source but may be the lens itself.

The TV originally used 6" crt tubes that measured 5 1/4" x 4 3/4".
The lcd i am using (when it gets here) is 4 1/8" x 3 1/8".

Now when the tv had its tubes it produced a great image that filled the screen until the main power board fried. So i ripped out the guts and decided to throw a Verge 5" lcd in it. The LCD is smaller then the original crt tube but refuses to produce a full screen image.

I have attached a link to my webspace that has all of the pictures so far. I am only using a plastic template right now that is identical in size to the lcd's screen.

Please take a look and advise me on what the problem may be.:D

Thanks, GordonPIctures are HERE
I think you need a fresnel

It looks to me like your setup is not sending any light through the corners of the "LCD" (plastic mockup) to the lens. CRTs emit light from all pixels pretty evenly, so you have to duplicate that when you switch to an LCD.

Try using a point-source lamp and a fresnel lens about 20 mm before the LCD. You could try a page magnifier from an office supply store, for a quick & dirty test. The lamp to fresnel distance should be at least the focal distance of the fresnel. Might be a bit brighter if that distance is a bit longer than the fresnel focal length. That would shape the light into more of a cone.

If you want to make it more compact, you can use two fresnels together. Their combined effective focal length (EFL) will be:

1/EFL = 1/fl1 + 1/fl2

So if they are identical, then the effective focal length will be half the individual focal lengths.

If you can match the cone of light coming from a parabolic flood to the input cone of the fresnel, then that could work too. Otherwise, you should put a spherical reflector behind a point source lamp.
the C lens thingy is still in there but the silicone cooling liquid is gone.

There is nothing blocking the light anymore as i have "trimmed" some brackets out of the way.

I should have the actual lcd here on Wednesday though for further testing.

This will work eventually i hope.

Thanks for the ideas so far,
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.