Here is my rough drawing for a 17" horizontal folded projector.

Being that I am a total rookie at this, how close am I to getting this right? I'm not sure of the exact projection distance or screen size, so I didn't bother going to great lengths doing the proper calculations for the Pro-zoom Lens yet. Right now, the drawing is based on a samsung 17" 16:9 monitor/tv with a video scaler built in. Not sure if that's the exact monitor that I'm going to go with (big $$$). Just wanted to get a rough estimate of what I could get away with for form factor.

So, what do you all think? Am I on the right track? have I made any gross errors at this point?

Interior dimentions (without cutting fresnals down) are 23" wide by 18 3/4" deep and 17" tall. I think if I were to have the fresnals cut down to height to match the LCD, I could get the interior height somewhere around 11"-12".


Viewed from the top of the projector

looks interesting, BRAIN, what do you think??????

Man, thats pretty sweet!
You could modify it so that the Pro Lens is pointing towards the ceiling or the floor with a mirror on the outside the box bouncing the image to the far wall for a slim design.
Nice


peace

How are you going to focus it?

This is just a rough drawing. The 100mm pro lense has a focus mech built in as I understand it, but I plan on making a sliding zoom adjustment box for it, so I can adjust the throw.

That's looks pretty cool...but did you take into account the size of the lamp and reflector and the lamp's horizontal orientation?

damn, I knew I forgot something! lol.

oh well, back to the drawing board, gonna have to extend the box a bit now..

ok the new interior dimentions are 25.5" x 17.5"

I'll post a pic once I get all the measurements in place.

Hey Thomas,
I've also decided to use a 17" LCD TV, 16:9, tuner, scaler, component/VGA/SVHS inputs, maybe Faroudja chip etc. inside. Could you tell me the exact measures of the viewable size of your 1280x768 panel? And then its outer sizes, please...
I'm planning a compact folded thing, too.

havn't got the panel yet. Still mocking up designs to see what the form factor will be before I commit to a specific LCD panel.

Ok here is the new rough drawing. I adjusted the case size to accomidate the horizontal placement of the lamp, and I changed the gap between the fresnals and the lcd panel (15mm for the collumator, 20mm for the field fresnal)

again this is based on the samsung 17" TV/Monitor. I don't have the lcd yet, so the dimentions that I used in the drawing were based on the viewable area spec from samsung.

anyway, my big questions are
1. Did I calculate the lense placements correctly?
2. Can anyone see any inhearant flaws in the design?
3. Will having a folded design like this screw up using the field fresnal for keystoning adjustment?
4. Any cooling "gotcha's" you can see in this layout?

Obviously the drawing is not complete, but I want to cross check the layout before I start drawing in more detail.

I see you corrected your distance from the lcd to the pro lens to 572mm. You will need to have a barrier to keep the light from the lamp interferring with the focal lens section of the enclosure. I like how you shaved off some of the excess box for a more compact look.

Neat design. Are you going to implement a moving lens board?

Yes, I plan to. I have a few ideas that I'm going to draw up for the lens board, keystone adjustment and even a lamp focal point adjustment with enough range to remove the bulb when needed.

Just hope it all fits in the unit!

BTW, anyone have the exact exterior measurements of the pro lens, or a diagram?

I LIKE that design, looking forward to update.

here's my other idea, but the cabinet and mirrors are a little more complex.

I'm looking to make a coffee table to incorporate one of these.


Here is the light and lense layout.

and the cabinet (there are a few drawing mistakes I've corrected since this copy)

and here are both together

And an updated version of the horizontal unit

Just wondering, do these designs ( or any with a single mirror) reverse or invert the image. Would yo have to install the LCD backwards in the later design. Verses the two mirror design ( I like that one ) , which seams like the orentation is unchanged?

Oh, just noticed.... I like the bulb !

When you talk about a light barrier, do you mean a barrier to block light from the lamp that might get past the fresnels and hit the back of the projection lens? Not really sure what you mean by focal lens section. So for example a small barrier next to the proj lens without interfering with the cone of light from the field fresnel, but not allowing the back of the projection lens to see the lamp?

Thanks.. Ed

This single mirror design has lots of promise. esp. with prolens and 17" monitor.
I like the small footprint, and shall look deeper.

R

I'm very interested in this design also.

Thanks Thomas for taking the time to do this and sharing your hard work. I may ask you later down the road if I can use your design.

Now to see Brains offerings.

edit: Wow Thomas the "Big Dog" has taken a liking to your design, nice job!


peace

Just wondering if the bigger measure can go under 20" if you break the light path BEFORE the LCD, too? (I mean between the lamp and the LCD.)
By e.g. putting the lightsource above the LCD (in line with the proj.lens) and the light could reach the LCD using a mirror.
It would be great if the whole thing could fit into a 20"x20"x20" cube...

I think we can reduce it to this size with another mirror

Nice work. The most compact design hitherto conceived is accomplished by placing the panel in the box leaning forward by 45º. This obviously shrinks the height dimension. It also requires a tricky compound angle on the final mirror; requiring 3 mirrors in total, with a loss of transmittance equaling 24%. While the novetly of such a design appeals to me aesthetically, the light and image losses, compounded by the complexity of the design are souring me on the project. The whole project shaved a few inches in each dimension. That said, my 17" has been sitting stripped for 6 weeks while I pack boxes and answer questions. I really want my 17" projector so I'm just going to build it based on simple ideas that split the divide between size and performance.

Good idea brain - ANd I'm not saying you should build that 17 because I have the same monitor as you and want to discover as many nasty surprises that may be involved..but ...well ok I am hoping you get started first so I can leech..

Beware. It looks like there might be a second path for the light to take (asside from the desired one). I'm talking about the 3 mirror design here. I think it could go from the buld straight to the LCD, off the other two mirrors, and through the lens, going who knows where (floor? ceiling?). While the main image would probalby make it out ok, there's probalby other stuff that would come out too.

Really this comment pertains to all folded designs. Light will go along the path you intend, but it may also go along some others!

The fix is simple enough, block off the bulb!

Back to beer inventing.

Brett

I tried for about 4 hours to come up with a way to get a mirror on the bulb side of the lcd also, but with the short focus length of the fresnal, it was impossible to isolate the bulb properly. To do it properly, I think a different fresnel with an extended focus length would be needed.


I was also trying to keep the design as simple as possible so I didn't have a anurism while trying to get all the mirrors aligned perfectly. The single mirror design was appealing to me just for the simplicity factor.

The duel mirror design I like because it would make a cool coffee table projector where the lense box protrudes above the table and the rest sits below.

I'm a long ways from building one because I'm in the process of having a new house built and moving and such, but I can't wait to get started on it.

What if you try to use two 330mm focus fresnels? One between the LCD and projecting lens as usual, and one between the lamp and the LCD? (instead of the 220mm one)

I found this funny when I first read it, we are already turning the LCD backwards, why would this be a problem?

My first thought is that this would mean that the pcb that has to be unfolded out of the way of the LCD into the lamp side of the box creating a possible cooling problem.

ahhh... There's the rubb.

R

a 330mm FL fresnal would do the trick, However I don't think the 330mm FL fresnal offered is not large enough for a 17" widescreen LCD :angry:

But for a a regular 4:3 15" it would be just fine. However, just using a regular 4:3 15" lcd in this layout would enable you to make things much smaller anyway without a mirror on the lamp side of the lcd.

ahhh, the decisions, decisions -- the inginuity, and thoughts, my head hurts..........
but, hey, I like the design, and the help from all - let's keep it up

ok,

was a little bored at work today, so I drew another one. This one is still 17" widescreen, but is setup for ceiling mount with a built in -15 degree projection angle.

This one is interesting to me because I have no idea what I'm going to have to do to get the keystone setting right. The fresnal by design is already parallel to the screen, and the mirror placement may induce some keystone already. You'll see in the rough drawing of the side view that I have drawn the lens in two different orientations. I really have no clue which one would be preferable in this instance. Anyone know the answer to this?

here is the side view

Here is the top view

here is the end view

and an isometric view of the cabinet

and one of just the optics

Thomas, any updates for the horizontal design with the ProLens?


peace

(quote)
When you talk about a light barrier, do you mean a barrier to block light from the lamp that might get past the fresnels and hit the back of the projection lens? Not really sure what you mean by focal lens section. So for example a small barrier next to the proj lens without interfering with the cone of light from the field fresnel, but not allowing the back of the projection lens to see the lamp?


Sorry this is so late. Yes, I was talking about making sure that the only light that passes to the front section of the enclosure goes through the lcd and fresnels. In a later revision Thomas closed off the section where light would have gone by the lcd and struck the front section near the focal lens. You want to prevent all stray light from entering that part of the projector.

Mark8261,

Thanks for the reply, that's kind of what I thought. Sometimes it's easy to just look at the light cone and forget stray light.

Regards..
Ed

Not a whole lot to update. It will be some time before I get my lcd to finilize the measurements. But I did make up a parts sheet/cut list for the case based on the current measurements. (see picture below)

Anyone who want's to try one of these plans out is more than welcome to. The original was made with autosketch (SKF). If you have a cad program that will accept DWG, DXF, or CAD (quick cad) extensions, I can save to those formats also. I will gladly email the original (of any of these) in it's current form to anyone who would like it.

This is very similar to what I'm currently planning for my proj - except with a 15" screen. The top portion containing the lamp, LCD, and first mirror will actually be recessed into my ceiling, between the joists.

At least, that's what I'm thinking right now. We'll see.

As for the optics, I think that you can still adjust keystone by moving the field fresnel lens by 15 degrees (which is right at the limit of what you can correct this way without causing some optical probs). As for the projection lens, it should be tilted so it's parallel to the screen - this helps keep the whole image in focus, but not more than 5 degrees off-axis.

This is just my understanding from a few months of reading on here - haven't built my PJ or experimented yet.


Hope this helps,
Phil.

Thomas, I just wanted to say those designs look fantastic. You've got some talent there. As soon as I get all my parts i'm going to start experimenting, and hopefully come up with something that works well.

Have fun,
Jason

Wow, ask and you shall recieve.

Thanks Thomas. Will be soon when I start mine and I will be using a design close to that one but more square.

A couple of questions to whom can answer.
With the box pointing up or down, would placing a mirror on the outside of the box to bounce the image to the far wall be possible? I really want the box to be sticking out as little as possible and this way seems to be the best.
And would this method be able to do the keystone adjustments, or would doing the keystoning with the second fresnal be better?

Thanks in advance.


peace

I was also thinking along similar lines for my hideaway design. It seems to me that if you have the mirror out near the focal point of the projection lens, you could actually use a very small mirror - like 1"x1" or something.

Wherever you put it, and however you size it, though, you can have the mirror outside the box. This exposes it to dust, but if you've got an appropriate cleaner and are prepared to use it now and then, it shouldn't be a big deal.


Hope this helps,
Phil.

Thanks for the reply Phil.
I'm thinking something along the line of a lid with a mirror on it that I can open up when in use and closed when not, so this design will have it placed before the focal point, so I'm hoping something like a 12"Deep x 10"Wide will be large enough for the projectors bottom being at a height of around 5' to 6' with the center of the screen being at 4'.
Mainly thinking of pointing the projector down now.


peace

hi there, just checking on your progress

thanks.
andy