4" LCD Projector
Hi I have a portable dvd player that still work but with a bad screen(TFT). Backlight(square tube) went out. I was wonder if it's possible to turn that in to LCD projector. I'm trying to get away from the big box projector (15" screen) I want to try to get it as small as possible as the same size as the real one for $1,000+. I dont really need 150", as long as I have a big enough screen 50"+. Anyone have suggestion?
I haven't had time to upload my plan diagram.
Hi I have a portable dvd player that still work but with a bad screen(TFT). Backlight(square tube) went out. I was wonder if it's possible to turn that in to LCD projector. I'm trying to get away from the big box projector (15" screen) I want to try to get it as small as possible as the same size as the real one for $1,000+. I dont really need 150", as long as I have a big enough screen 50"+. Anyone have suggestion?
I haven't had time to upload my plan diagram.
The chances are that the screen will have an appalling resolution, slow response time and poor contrast ratio, however if you think you can live with these then there's no reason not to use it. I'd imagine it would be ok on a small projection screen if you're planning to use it to watch TV, don't expect cinema / theatre quality from it though.
One thing you will need to do is to ensure that any circuitry behind the LCD can be folded out of the way, preferably before destroying your player altogether. You might need to extend an FCC cable (flat small ribbon cable) or two which whilst a bit fiddly isn't too expensive.
If you find that you can't fold the circuitry out of the way then maybe take a look at the Lilliput screens or the PS2 screen, people on here have managed to get some very good results with them. Again they're fairly cheap and I believe are easy to work with.
Have you looked for other parts yet? You may need to be careful with the bulb dimensions as some can be quite long and therefore would needlessly increase the size of your box. At least if you are only after a small projection screen then you can go with a 250W MH bulb or equivalent.
HTH, hopefully others have some points to add.
Steve
One thing you will need to do is to ensure that any circuitry behind the LCD can be folded out of the way, preferably before destroying your player altogether. You might need to extend an FCC cable (flat small ribbon cable) or two which whilst a bit fiddly isn't too expensive.
If you find that you can't fold the circuitry out of the way then maybe take a look at the Lilliput screens or the PS2 screen, people on here have managed to get some very good results with them. Again they're fairly cheap and I believe are easy to work with.
Have you looked for other parts yet? You may need to be careful with the bulb dimensions as some can be quite long and therefore would needlessly increase the size of your box. At least if you are only after a small projection screen then you can go with a 250W MH bulb or equivalent.
HTH, hopefully others have some points to add.
Steve
4" LCD
If the LCD is really only 4" diagonal, then you can make a very tiny simple projector using a CRT projection lens. These go for under $15 on eBay and surplusshed.com all the time, and can project up to a 5" LCD. This kind of lens goes right up against the LCD, which makes for a small box.
I would put a 150 Watt double-ended MH lamp behind it with the shortest focal length fresnel you can find (maybe 200 mm?) as a condensor about 25 mm before the LCD. The lamp to fresnel spacing would be the same as the focal length of the fresnel.
Add a spherical reflector for the lamp, some fans, UV and IR filters, and you will have a very small projector that can make a small screen image that will be limited only by your LCD's resolution. But you could start with the $15 lens and a bright incandescent floodlight to see what the image quality will look like before buying any of the rest.
If the LCD is really only 4" diagonal, then you can make a very tiny simple projector using a CRT projection lens. These go for under $15 on eBay and surplusshed.com all the time, and can project up to a 5" LCD. This kind of lens goes right up against the LCD, which makes for a small box.
I would put a 150 Watt double-ended MH lamp behind it with the shortest focal length fresnel you can find (maybe 200 mm?) as a condensor about 25 mm before the LCD. The lamp to fresnel spacing would be the same as the focal length of the fresnel.
Add a spherical reflector for the lamp, some fans, UV and IR filters, and you will have a very small projector that can make a small screen image that will be limited only by your LCD's resolution. But you could start with the $15 lens and a bright incandescent floodlight to see what the image quality will look like before buying any of the rest.
4" LCD Projector
Thanks for the advice and suggestion guys. I will try it and learn as i go. These are what i'm working with just to get the idea of projection.
Mintek 5" 4:3 Portable DVD TFT with the player outside the box.
Kodak Lens F:2.8 102mm (heard that it's wrong choice)
Plastic Fresh Snail Len
Home Torcheire Halogen Lamps
I like that plan from ....i forgot the ID......5" PS1 LCD screen. I think that's small enough for me.
OH, I put 4" screen instead of 5"
Thanks for the advice and suggestion guys. I will try it and learn as i go. These are what i'm working with just to get the idea of projection.
Mintek 5" 4:3 Portable DVD TFT with the player outside the box.
Kodak Lens F:2.8 102mm (heard that it's wrong choice)
Plastic Fresh Snail Len
Home Torcheire Halogen Lamps
I like that plan from ....i forgot the ID......5" PS1 LCD screen. I think that's small enough for me.
OH, I put 4" screen instead of 5"
halogen lamp
The one advantage of a CRT projection lens is that you can be pretty sloppy about the lighting, and still get a reasonable image. If you really want to try one of those long skinny halogen tubes, then I would make a beer-can reflector: Cut open an aluminum can by cutting off the ends and then making one neat cut up the side. (Wear gloves! Very easy to cut yourself doing this.) Then open it up and form a two dimensional parabola. You may have to add some wood or metal pieces for the sides to keep the can metal in the right shape. If you put your halogen tube an inch or so from the center of the parabola, you should get a pretty even parallel beam from the whole reflector surface. Play around with the shape until you do.
Put that right behind the LCD and it should work okay without any fresnels at all, as long as you are using a CRT projection lens that is as large as the LCD.
If you want to use a smaller lens, then you will have to use fresnels to condense a point-source lamp's light into the lens.
Either way, a halogen lamp will give you a yellow-tinted image. Not as bad a those parking lot sodium lights, but metal halide lamps look much whiter.
The one advantage of a CRT projection lens is that you can be pretty sloppy about the lighting, and still get a reasonable image. If you really want to try one of those long skinny halogen tubes, then I would make a beer-can reflector: Cut open an aluminum can by cutting off the ends and then making one neat cut up the side. (Wear gloves! Very easy to cut yourself doing this.) Then open it up and form a two dimensional parabola. You may have to add some wood or metal pieces for the sides to keep the can metal in the right shape. If you put your halogen tube an inch or so from the center of the parabola, you should get a pretty even parallel beam from the whole reflector surface. Play around with the shape until you do.
Put that right behind the LCD and it should work okay without any fresnels at all, as long as you are using a CRT projection lens that is as large as the LCD.
If you want to use a smaller lens, then you will have to use fresnels to condense a point-source lamp's light into the lens.
Either way, a halogen lamp will give you a yellow-tinted image. Not as bad a those parking lot sodium lights, but metal halide lamps look much whiter.
5" LCD Projector
Hey thanks again for the help Guy. I look under "CRT PROJECTOR LENS" on ebay I don't see any under $50. With "BUY IT NOW" filter, I saw $70 plus $30S&H the cheapest price. I went to surplusshed.com and I didn't know what to put in the search because there wasn't "CRT" for me to select. You're probably saying "dang, this boy!" Well, I'm a newbie
Hey thanks again for the help Guy. I look under "CRT PROJECTOR LENS" on ebay I don't see any under $50. With "BUY IT NOW" filter, I saw $70 plus $30S&H the cheapest price. I went to surplusshed.com and I didn't know what to put in the search because there wasn't "CRT" for me to select. You're probably saying "dang, this boy!" Well, I'm a newbie
CRT projection lens
Here is an expensive example from eBay. I have seen a lot of these go for more like $15 US:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=32862&item=5765839493&rd=1
The lens specs would be at least 5" (125 mm) diameter, focal length in the 6" to 8" range (150 to 200 mm). If they only tell you focal length and f-ratio, then diameter = fl / f-ratio. So a 200 mm fl f1.6 would have a diameter of 125 mm.
It doesn't look like surplusshed has any right now, but you could try doing a google (or froogle) search for "CRT projection lens". There was also mention on some thread in this forum about somebody having around 50 of them in his basement.
Here is an expensive example from eBay. I have seen a lot of these go for more like $15 US:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=32862&item=5765839493&rd=1
The lens specs would be at least 5" (125 mm) diameter, focal length in the 6" to 8" range (150 to 200 mm). If they only tell you focal length and f-ratio, then diameter = fl / f-ratio. So a 200 mm fl f1.6 would have a diameter of 125 mm.
It doesn't look like surplusshed has any right now, but you could try doing a google (or froogle) search for "CRT projection lens". There was also mention on some thread in this forum about somebody having around 50 of them in his basement.
Re: CRT projection lens
That would be Curt Palme. If you're interested in that type of lens you can contact him here http://www.curtpalme.com/
Guy Grotke said:
That would be Curt Palme. If you're interested in that type of lens you can contact him here http://www.curtpalme.com/
I'm about to start buying parts.... let me know if I'm missing something, or if there's a better part I could be using.
LCD: ProView PL576Ws 15.4" Widescreen LCD Display
Lamp: UHI-S400DD USHIO
Ballast: High Pressure Sodium Sola/Howard (maybe something else???)
Lense: 135mm Long-Throw Projection Lens Triplet
Fresnel: 320mm x 400mm 550mm FL (I'm doing a split design and I don't know what the first fresnel should be)
Reflector: i don't know
I'm using a 15" LCD so I don't need a condensor lense right?
LCD: ProView PL576Ws 15.4" Widescreen LCD Display
Lamp: UHI-S400DD USHIO
Ballast: High Pressure Sodium Sola/Howard (maybe something else???)
Lense: 135mm Long-Throw Projection Lens Triplet
Fresnel: 320mm x 400mm 550mm FL (I'm doing a split design and I don't know what the first fresnel should be)
Reflector: i don't know
I'm using a 15" LCD so I don't need a condensor lense right?
good stuff!
redd38:
That stuff you listed will work fine. If you get a 200 to 220 mm fl condensor (first) fresnel (such as lumenlabs or 3dlens), then put it that same distance from the lamp arc. With this kind of geometry, a pre-condensor lens would not be worth the trouble.
If you get a 330 mm fl condensor fresnel, then the right pre-condensor lens would help gather more light. But, I would just use a 220 and not bother with a pre-condensor lens.
You can pay a lot for an optical-quality spherical reflector from places like Edmonds, but again I would not bother. Try a polished stainless steel mixing bowl from one of the DIY projector sites. They are under $10 precut to fit your Ushio lamp.
Don't forget UV & IR filtering, and one or more fans for forced-air cooling.
redd38:
That stuff you listed will work fine. If you get a 200 to 220 mm fl condensor (first) fresnel (such as lumenlabs or 3dlens), then put it that same distance from the lamp arc. With this kind of geometry, a pre-condensor lens would not be worth the trouble.
If you get a 330 mm fl condensor fresnel, then the right pre-condensor lens would help gather more light. But, I would just use a 220 and not bother with a pre-condensor lens.
You can pay a lot for an optical-quality spherical reflector from places like Edmonds, but again I would not bother. Try a polished stainless steel mixing bowl from one of the DIY projector sites. They are under $10 precut to fit your Ushio lamp.
Don't forget UV & IR filtering, and one or more fans for forced-air cooling.
no
Car headlights are parabolic, with the lamp filament a bit deeper into the "dish" than the focal point. That makes the resulting beam spread slightly.
A spherical reflector is used with the lamp arc placed at the exact center of curvature. Every ray that hits the reflector is reflected right back through the lamp arc and out the other side. The condensor fresnel "sees" all of this as a single bright point source. If the distance from the lamp arc to the condensor fresnel is exactly the focal length of the fresnel, then parallel rays will come out the other side of the fresnel. A field fresnel can then be used to focus all of those parallel rays to a point inside the projection lens.
There are other possible ways to do it, but any design that can't focus most of those rays into the projection lens will not give you a bright screen image.
Car headlights are parabolic, with the lamp filament a bit deeper into the "dish" than the focal point. That makes the resulting beam spread slightly.
A spherical reflector is used with the lamp arc placed at the exact center of curvature. Every ray that hits the reflector is reflected right back through the lamp arc and out the other side. The condensor fresnel "sees" all of this as a single bright point source. If the distance from the lamp arc to the condensor fresnel is exactly the focal length of the fresnel, then parallel rays will come out the other side of the fresnel. A field fresnel can then be used to focus all of those parallel rays to a point inside the projection lens.
There are other possible ways to do it, but any design that can't focus most of those rays into the projection lens will not give you a bright screen image.
very small projector
Hello All,
I have been reading through these posts for two days now trying to gain some insight into building a custom video projector.
I am currently working on a project where a very small projector is needed to fit within an internal cavity...a robotics app.
There are a few products coming out at the end of the year...the pocket projector type video projectors. A friend saw one at a trade show this week and said that the mitsubishi one...although small, is still very dim in a dark room.
I would like to try my hand at a home made version before paying 1000+ for a product that doesnt quite seem there yet.
I have a 2.5" lcd screen from accelvision...their products are quite good.
I have been looking at the luxeon v portable l.e.d. for a light source.
Aside from that I would need a lense assembly that can fit within a 1.5" diamter cavity.
I cant really go with a lamp due to the regual heat/fan issues.
Based on what I have read I still need to spec a fresnel lense (x?) and the lense...as well as filters?.
What I ultimately need to do is produce a 2-3' image on a screen if possible with the projector being a few feet away from the screeen surface.
I am not expecting crisp bright home theater pictures...but I would like to know if it is possible to rig something up that is at least on par with the pocket projector forecasts.
Any help would be greatly appreciated.
Thank you in advance
Jason
Hello All,
I have been reading through these posts for two days now trying to gain some insight into building a custom video projector.
I am currently working on a project where a very small projector is needed to fit within an internal cavity...a robotics app.
There are a few products coming out at the end of the year...the pocket projector type video projectors. A friend saw one at a trade show this week and said that the mitsubishi one...although small, is still very dim in a dark room.
I would like to try my hand at a home made version before paying 1000+ for a product that doesnt quite seem there yet.
I have a 2.5" lcd screen from accelvision...their products are quite good.
I have been looking at the luxeon v portable l.e.d. for a light source.
Aside from that I would need a lense assembly that can fit within a 1.5" diamter cavity.
I cant really go with a lamp due to the regual heat/fan issues.
Based on what I have read I still need to spec a fresnel lense (x?) and the lense...as well as filters?.
What I ultimately need to do is produce a 2-3' image on a screen if possible with the projector being a few feet away from the screeen surface.
I am not expecting crisp bright home theater pictures...but I would like to know if it is possible to rig something up that is at least on par with the pocket projector forecasts.
Any help would be greatly appreciated.
Thank you in advance
Jason
tiny projector
Scaling down from the size of my screen, a 4000 - 5000 lumen light source should give you a nice image in a dark room, not so nice in a well-lit room. If you can find that in an LED, then you might be able to make it work. (But I doubt that you can: LEDs are LESS efficient than Metal Halide lamps, so they make more heat per lumen.) You could do it with a 40 - 50 Watt MH lamp & ballast. If that is too bulky, then you might consider an exotic car headlight. Or maybe just a small 100 Watt halogen lamp with a good heat mirror to cut the IR.
You could use a fresnel condensor system, but your LCD is small enough that you could use a regular convex lens instead. surplusshed.com has several in that diameter or larger for about $6 US.
I think your main difficulty will be the tight space: You won't have much room for long focal lengths. A parabolic reflector eliminates the need for a condensor fresnel. You can put it very close to the LCD. The projection lens would have to be around 75 mm fl, to get a 27.5" image from 3 feet. The LCD to lens distance would be around 81 mm. Not bad. With this design, a 90 mm fl field lens placed about 10 mm before the LCD would direct all the light into your projection lens.
Scaling down from the size of my screen, a 4000 - 5000 lumen light source should give you a nice image in a dark room, not so nice in a well-lit room. If you can find that in an LED, then you might be able to make it work. (But I doubt that you can: LEDs are LESS efficient than Metal Halide lamps, so they make more heat per lumen.) You could do it with a 40 - 50 Watt MH lamp & ballast. If that is too bulky, then you might consider an exotic car headlight. Or maybe just a small 100 Watt halogen lamp with a good heat mirror to cut the IR.
You could use a fresnel condensor system, but your LCD is small enough that you could use a regular convex lens instead. surplusshed.com has several in that diameter or larger for about $6 US.
I think your main difficulty will be the tight space: You won't have much room for long focal lengths. A parabolic reflector eliminates the need for a condensor fresnel. You can put it very close to the LCD. The projection lens would have to be around 75 mm fl, to get a 27.5" image from 3 feet. The LCD to lens distance would be around 81 mm. Not bad. With this design, a 90 mm fl field lens placed about 10 mm before the LCD would direct all the light into your projection lens.
Guy,
Thanks for the tips.
As you can tell I am new to this end of design.
I did a few more hours of research after my original posts and read your comments about MH light sources.
Any idea if there are dc versions? The system is needs to be portable and I have a limited 24v dc supply onboard.
With approx. 7.2 aH of juice I fear a MH bulb and a dc to ac convertor isnt going to result in long viewing times.
Any alternative you can think of?
Other question I have is...due to the small space...what is the likelyhood of a triplet magnifier vs. a projection lense working?
Thanks for the tips.
As you can tell I am new to this end of design.
I did a few more hours of research after my original posts and read your comments about MH light sources.
Any idea if there are dc versions? The system is needs to be portable and I have a limited 24v dc supply onboard.
With approx. 7.2 aH of juice I fear a MH bulb and a dc to ac convertor isnt going to result in long viewing times.
Any alternative you can think of?
Other question I have is...due to the small space...what is the likelyhood of a triplet magnifier vs. a projection lense working?
lamps & lenses
There are DC MH lamps, but they all take more like 90 volts. I think you are stuck with halogen tungsten. I am sure you could find a wide assortment of very bright marine halogem lamps that run on 24 VDC. Color LCD projectors are very inefficient: As I said earlier, I think you will need 50-60 Watts of lamp to get a viewable image. You can do the math...
Regarding the projection lens: Does the image need to be perfect? Maybe a little barrel distortion would look okay for this application. In that case, you could just use a simple planoconvex or positive meniscus lens. Hard to beat $6 from surplusshed.com.
If it does need to be perfect, then you need a projection lens. A magnifier will not be optimised for a wide enough field of view. The problem is that you need something with around 75 mm fl to get the image size at the throw distance you mentioned. It will have to cover the 63 mm wide LCD from a distance of 81 mm, so it will need a pretty wide angle FOV. Maybe a large format camera lens?
There are DC MH lamps, but they all take more like 90 volts. I think you are stuck with halogen tungsten. I am sure you could find a wide assortment of very bright marine halogem lamps that run on 24 VDC. Color LCD projectors are very inefficient: As I said earlier, I think you will need 50-60 Watts of lamp to get a viewable image. You can do the math...
Regarding the projection lens: Does the image need to be perfect? Maybe a little barrel distortion would look okay for this application. In that case, you could just use a simple planoconvex or positive meniscus lens. Hard to beat $6 from surplusshed.com.
If it does need to be perfect, then you need a projection lens. A magnifier will not be optimised for a wide enough field of view. The problem is that you need something with around 75 mm fl to get the image size at the throw distance you mentioned. It will have to cover the 63 mm wide LCD from a distance of 81 mm, so it will need a pretty wide angle FOV. Maybe a large format camera lens?
lense
Guy,
Thanks again for the help.
This part of the project is turning into its own little nightmare.
I was wondering if you had any links for acceptable yet small diameter projection lenses. I need the overall diameter of the lense assembly to be no larger than 1-1.25"...case included in that spec.
I know they exist...I saw a infocus lp120 today with a pretty small lense on the front end.
Have you come across a supplier for any such beast?
Guy,
Thanks again for the help.
This part of the project is turning into its own little nightmare.
I was wondering if you had any links for acceptable yet small diameter projection lenses. I need the overall diameter of the lense assembly to be no larger than 1-1.25"...case included in that spec.
I know they exist...I saw a infocus lp120 today with a pretty small lense on the front end.
Have you come across a supplier for any such beast?
possible lenses
look at these at surplusshed.com:
http://www.surplusshed.com/detail.cfm?ID=L1196
http://www.surplusshed.com/detail.cfm?ID=L3277
http://www.surplusshed.com/detail.cfm?ID=L3278
The first is a simple lens that would fit within a 1" hole, and give you the size image & throw distance you mentioned, with a 2.5" LCD. But it will not have an image that focusses at the center and the corners at the same time.
The latter two are good multi-element lenses, but their mounting may be too large for you. Their light paths would not be all that large, so maybe you could mount one sticking out from the surface of your robot. Actually, at these prices (ie. $7 each) you could get two to mount on the "head": Use one for projection and the other for machine vision.
What about the 2.5" LCD you mentioned? That is not going to fit in a 1.25" wide chamber!
look at these at surplusshed.com:
http://www.surplusshed.com/detail.cfm?ID=L1196
http://www.surplusshed.com/detail.cfm?ID=L3277
http://www.surplusshed.com/detail.cfm?ID=L3278
The first is a simple lens that would fit within a 1" hole, and give you the size image & throw distance you mentioned, with a 2.5" LCD. But it will not have an image that focusses at the center and the corners at the same time.
The latter two are good multi-element lenses, but their mounting may be too large for you. Their light paths would not be all that large, so maybe you could mount one sticking out from the surface of your robot. Actually, at these prices (ie. $7 each) you could get two to mount on the "head": Use one for projection and the other for machine vision.
What about the 2.5" LCD you mentioned? That is not going to fit in a 1.25" wide chamber!
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