How Digital Light Processing (DLP) works
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- เผยแพร่เมื่อ 8 มิ.ย. 2024
- Digital Light Processing projectors use a chip that is covered with tiny mirrors that tilt back and forth. When the mirror is tilted one way, it reflects light out through the front of the projector, creating a bright pixel. When the mirror is tilted the other way, the pixel is dark. In this video, I explain how DLP works and show a macro-scale model.
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Yessss!
Am I the only one thinking "holy shit we are able to create and assemble mechanically moving objects so small that you need an SEM to look at them" ?
That is amazing. Sure nobody bats an eye anymore at 22nm processors but.. We're talking actually mechanically moving things
I agree. It is pretty amazing. What's even more amazing is that we use devices with this kind of complexity every day, and don't bat an eye. Or the fact that you can buy a chip made using this super complex and mega-expensive-to-develop manufacturing technology for literally .1$ a pop.
It won't be a very interesting IC chip, but, doesn't mean it's not amazing that it exists and is sold for basically nothing!
Not only do you need powerful microscopes to look at some of these mechanical system, but we have even brought down mechanical systems to the point where their vibrational modes need to be treated quantum mechanically. See eg k-lab.epfl.ch/page-102900-en.html
MEMS (Micro Electromechanical Systems)
en.wikipedia.org/wiki/Microelectromechanical_systems
NEMS (Nano Electromechanical Systems)
en.wikipedia.org/wiki/Nanoelectromechanical_systems
***** There is an effort underway to make a Babbage engine about 1 cm on a side. Why? Parts that tiny can run at millions of operations a second. A Babbage machine can do a lot in a single clock cycle.
+Cooking With Cows I'm totally amazed too. I was hoping he would go into the other method of getting all the colours. Same principlal with the mirrors but there are 3 light sources pointing from different angles. So the mirrors have to move in more directions, even more tiny moving parts.
Adding a few more things, I spent several months doing competitive analysis of DLP chips when I worked at Hewlett Packard. The torsion hinge is not silicon but a titanium/aluminum alloy. Lots of interesting material properties of Ti/Al I won't get into here.
The most important thing missing from the narrative is that this device was the first truly micro electro-mechanical device. I say that because it is not just electrostatics that are responsible for the mirror motion. If you look carefully at the SEM images, you will see that, under the mirrors, there 4 little tabs attached to the posts. These are actually tiny springs. When a mirror is flipped to one side, the electrical force holds it down. What is really interesting here is that when it is time to flip the mirror, a short voltage spike is applied to the "down" side. This pulls the mirror down on these little springs then lets it go. The result is a very fast flip to the other side where there is a voltage applied to hold it there until it is time to flip it the other way.
If you are wondering why it is this way, think about the inverse square law. On the down side, the mirror is about 100 nanometers from the electrode. On the up side, the mirror is a couple of microns from the electrode. The force on the down side is hundreds of times that of the up side. It will flip by pulling from the up side but it will be way too slow for a video projector. Pull down really hard for a microsecond then let go and the mirror flips really fast! Pretty cool technology from TI.
Note that Hewlett Packard didn't ever produce a projection chip. They spent a lots of millions and couldn't come up with something that could do better that the DLP chip. But, that's another story...
that's fascinating! the stronger force available is in the wrong direction, so use that to pull it against a spring and then let go... clever. I just assumed that they used the piezo effect to move the mirrors. Any short explanation as to prefering electrostatic?
cool
wow how can you make something so small and perfect?. if we can make tech that small then whats keeping us from making nanobots?
Very interesting info. Thanks !
I worked on DMD for about 12 years.
Just so you know i was lurking through internet at 3:00 am in the morning, found this video and decided to watch it instead of sleeping ! nice video and keep them coming !
If you ever come across a 3 channel projector, they have a really neat prism inside for splitting and recombining combining the light.
I recenty bought an old 3 chip DLP projector off of ebay just so I could take it apart.
Fascinating stuff inside this thing. Might make a video!
I work on cinema projectors for a living. Those 3 DMD chip light engines are super fascinating and make up the majority of modern day cinema projectors. Single DMD chips are cool to with the color wheel they instead of the prisms.
This is a necessary video because other videos tend to emphasize CGI and theory. However, this is one of those technological subjects where the old fashioned approach works best. Great video and thanks for your hard work.
You nailed it nicely!
Thumbs up from a projector sales guy of 15 years ago!
This was the best video on DLP projector technology I've seen. I love your channel. You could have made a simple color wheel to explain the secret sauce: the timing between the DMD and the wheel, but even without that, this video was excellent. Thanks!
Interesting video, Ben. It would be cool to see your macro-DLP in action. It'd also be cool to see the area in the projector that the mirrors reflect light to when not sending it to the lens - a negative I guess.
I like the idea of taking the "negative" image and displaying it on a screen.
Interesting?! That was mind blowing! I've always wondered how those work.
Same here.
How does it create black? :)
***** Basically the mirrors are pulled so that they reflect the light away from the lens so that it stays within the projector instead of going onto the screen. Also, nice seeing you around here! I have watched many of your videos!
@@possiblydavid it's been five years, but five years too long that you didn't catch that this was obviously, blatantly sarcastic.
Whoa, this was way more amazing than I thought. Thank you so much for detailed and well presented video. Seeing the actual physical item is so much amazing than an animation.
I just cannot imagine how much work has been put into the manufacturing process of this. The engineers that started this idea must've been extremely ambiguous to make this concept a reality. I can hardly even believe it.
As ever Ben, you offer a clear and accessible study of things. Many thanks for sharing your passion for investigating and questioning how things work!
I'd just like to say that I have been watching your videos for about a year or so now and they are amazing little lessons into your line of work and expertise. I believe the quality of the "lessons" have improved greatly and I am eager to see how this evolves in the future.
Thanks! I really appreciate your comment. Practice certainly makes it easier for me to make better videos. I've deliberated whether adding higher production value items (intro/outro, clickable links, animations, voice-overs, better shot setup, etc) would be worthwhile. I think that many folks watch my content because the videos are clear, but do not have any high production value features. They are also free of BS, rambling, paid placement, etc. On the other hand, I do wish that I could show certain concepts with animations that are more illustrative than my drawings. Let me know what your thoughts are.
Applied Science
I am part of the audience that appreciates the clarity, lack of paid placement and lack of rambling (although I think rambling can build a type of ethos similar to Q&A at the cost of clarity). I would not trade any of these "virtues" for animations (your paper ones are pretty good). I think links improve the quality of the lesson and increase chances of people watching other videos of yours and give us an idea of the sources you use. I think you already have great shot setup, voice-over and outro. I think the fact that you respond to a high number of comments is also very admirable and enhances your educational value. This channel is a great example for TH-cam education. I too am interested in the future of education and will certainly look to your channel when I finish my current schooling (PhD microbiology... I love the SEM pictures you take. I'm currently using one for my research and it is how I found your channel in the first place :D) as an example of how I might set up my own TH-cam content. Thanks again!
Here's the teardown video of the projector this DLP came from th-cam.com/video/RzikiKqbA1U/w-d-xo.html
mikeselectricstuff Interesting how they use three DMD chips and a dichroic prism to combine the colors rather than a color wheel. I wish they used that method at my local cinema, because it's distracting whenever I move my eyes quickly and see the color separation.
lednerg Indeed, I saw this yesterday and wondered why it was happening
+lednerg Thats wierd. I was under the impression the color wheel derived DLP systems were consumer grade stuff and the commercial units like for theaters always had separate light sources or a prism. Interesting.
+lednerg That's bullshit that these theaters are using digital projectors. Film still looks amazing, and I can totally tell when a movie is being projected by a digital projector. I dont want to pay $13 to basically watch projected video. Especially when the technology is not good enough that the average viewer can easily see the flaws, like the DLP rainbow effect, or the screen door pixels.
A new theater opened up by me that doesn't have the color separation problem, so that's definitely where I'm going from now on.
DarthHater100 I saw Hateful Eight in 70mm at one of the few theaters that still has a film projector available. It actually took maybe 10 minutes for me to adjust to the 48hz strobing, something I hadn't anticipated. The picture was absolutely gorgeous, well worth going out of my way to see it.
Wow!! I took apart one of DLP-s and I found this chip, and I didn't know how this thing works without polarisation. I thought that is a normal LCD chip with mirror behind. Thank you very much for this insight! I can't believe that this projector is actually mechanical! Good work Ben, I'm looking forward to more awesome videos! Take care! :)
As a kid we got a tour of a movie theater. They said that there are thousands of mirrors. I thought that they meant they were layered on top of each other. This is cool to see it under microscope, it makes way more since now.
I always wondered what kind of "pixel" projectors used! But when I see the electron microscope image, now I wonder how on earth that can be manufactured. such tiny machinery...
Its one of the best channels on YT Man !
Tons of knowledge for free and a good quality one - in depth and interesting.
One of the rare internet treasures - I think I will back it up form my children.
for some reason this is even more amazing to me than a microprocessor, how do you make a mirror that small, how do you make that something mechanical this small operate reliably, probably millions of DLP projectors that have been running for 20 years now still out there still working.
Very clear and concise explanation of DLP technology.
Cool, thanks.
I knew most of the theory, but what your videos add is always the hands-on part, actually seeing the real stuff. The missing link between theory and practice.
Thank you for the extremely well thought out presentation concerning the T.I. DSL properties and complete explanation of that proprietary system. I have a pico-projector that implements the DSL and I have always wondered why I would catch a glimpse of the RGB in their singular state when walking by the projector or moving my head/eyes just right. That is one hell of a system and can only imagine how smart the individual is that was able to put it all together and have it work so well.....thanks again!
The first HDTV I ever owned was a Samsung DLP set... It was one of the earliest DLP TV sets, and it suffered from major design-flaws in the "light-tunnel" and the color wheel. The "light-tunnel" was, quite literally, a tunnel lined with mirrors that was supposed to channel light straight into the DLP chip. Stupidly, they designed it such that every *other* mirror in the tunnel was held in place with glue, and the ones that weren't held in place with glue were held in place by friction from their neighboring mirrors. So, eventually, the mirrors dropped off the sides of the "light-tunnel" and reduced the amount of light reaching the DLP chip.
The color-wheel was the 2nd problem -- it used a stepper-motor to "align" the colors with the DLP chip, which was completely ridiculous -- all it took to screw that up was one little glitch in the stepper-motor, and suddenly the colors weren't aligned properly with the picture that the DLP chip was displaying, so everything looked like a rainbow. After 3 years or so, the set was so badly compromised, that I had to toss it out and buy a new TV. Really ticked me off, too, because when it was brand-new it had a picture that was far better than any LCD or Plasma set of its day. I wish they had designed that set better.
What a piece of art and technology! Thanks for bringing this so elegantly to our attention!!
it was very interesting and informative and i thought that was all.. then you pulled out the electron microscope...
What's also amazing is the computing and switching power to control, organize and synchronize all this stuff to make it work.
fantastically throughout and well explained; loved the visual aids and macro model!
finish this and play tetris on the wall.
Awesome video, very cool. I'm surprised you don't have more subscribers. Your videos are some of the most interesting and informative videos on TH-cam.
Thank you for a great introduction to this technology. Very inspiring.
This is so much better than those animated videos trying to explain the same thing, thanks a lot!
Excellent, makes this very easy to understand - thank you.
Thanks for sharing. The explantion is excellent as allways.
really liked your video buddy no skipping or anything :) watched the whole thing
Very nice and clear video. Thanks for uploading.
how are the tiny mirrors made and places where they need to be? Is it a chemical process like etching away the parts you don't need?
Good question. Yes, the chip is made by a photolithographic process, just like silicon integrated circuits. The mirror itself is made by depositing a relatively thick layer of aluminum, then etching away all of the metal between mirrors. The process will also likely require a dissolvable support material that holds the aluminum layer at the correct height, then is washed away to allow the mirror to pivot freely. I'm not sure if the DMD chip is evacuated or has an inert gas charge -- probably vacuum.
I'd like to add that often a process called MEMS "machining" (Microelectromechanical Systems) is employed nowadays in which layers are added and removed using various processes such as lithography, electron beam etching, and vapor deposition (among many many other). MEMS technology is extremely useful for manufacturing micro scale mechanical systems including gears, springs, etc. If you do a google search for "MEMS gear" there's a cool image of a spider mite sitting on top of a rack and opinion made through MEMS processes. This is also the same technology used to make digital accelerometers and gyroscopes used in everything from cell phones to F22 raptors.
gizmoguyar
www.google.com/search?tbm=isch&q=%22MEMS+gear%22
I think they etch silicon the same way they do microchips, gyro's, and accelerometers.
gizmoguyar (I did a google image search.... ) AMAZING! Awesome tiny mechanics and machines! Thanks for the info.
I study Micro & Nano Systems Engineering, and this video was really helpful as an example. Thanks for the effort! It was amazing.
Very well explained i have just purchased a DLP HD projector and am amazed that one bulb can create such an amazing picture and wanted to know how and now I do thanks grate video.
Very ingenious demonstration model.
Great tutorial !!. Congrats !! I needed to understand DLP technology in an easy way. This video worked for me!. Thanks a lot !!
Very good explanation of DLP. Always did wonder, nut never looked it up.
Great videos. Keep up the good work.
I love this micro suspension! Great episode as always!
Superb and excellent way to make people like me understand about the mechanisms behind DLP projection.
Hats off to you for the hard work done by u to build this working mirror mechanism it’s amazing …
Thanks for sharing this complex knowledge behind DLP Chip …👏
Thanks for showing the DLP chip under the SEM. Now I know why early DLPs were prone to pixel failures.
great video with outstanding explanation
just replaced the DLP chip in my Mitsubishi. Super interesting to see in 'innards'. Off to see how they manufacture it now. Amazing to be able to work in such small detail.
My electromagnetics professor worked for TI and did RnD for the DMD. He gave two lectures explaining the math behind the forces of the torsion spring and the 'capacitor' (gap between mirror-plate and electrode).
The steady state relationship between the force of the torsion spring and the force between the two plates of the capacitor relative to the change in distance between the plates of the capacitor with only one intersection where the forces are equivalent, yields an astounding simplification where all variables (voltage, area of plates, spring constant) except one cancel out, leaving only the distance between the capacitor, d/3.
The d/3 represents the steady position held when the mirror is 'turned on'. When the force of the spring is equivalent to the force of the mirrors electrostatic attraction to the electrode. Which can then be calculated into the angle at which light is reflected from the mirror ... and thereby all of the mirrors in the array.
Another elegant simplification for a boundary of the laws of physics, all because we want to watch cool movies on bigger screens.
physicstasks.eu/3250/capacitor-with-plate-on-a-spring#:~:text=Air%20capacitor%20consists%20of%20two,down%20(the%20plates%20remain%20parallel.
Wow! Well done! Thanks for the video. Very clever science taking place.
I am so glad I found your channel. Great stuff!!!
I learnt loads from this. Great presentation , thanks!
Wow! Such a great explanation once again, Ben! Thanks.
Excellent illustration!
LOVE your videos! I work at the US Patent & Trademark Office in Circuits and it's cool to see everything in person!
This is a very useful intro to DMD / DLP, many thanks!
Nice video ! Impressive technology :o
Coolest thing I've seen in a while. I had no clue how it worked. Thanks
Awesom explanation. Thanks for your time and efford!
Great informational video. Loved it
Definitely an interesting video as I begin to research and muck about with DLP 3D printing.
That is so much more complicated than I had expected
Well done! Truly enjoyed this video!
That was really interesting. I have always wondered how these things work. Thanks!
Once took one of these apart and couldn't figure out how it worked.
Thanks for the explainer :)
You never cease to amaze. Thank you!
Great explanation, and great video
Ben, your channel is sweet. It's like a modern, more technical version of an old favorite of mine The Secret Life of Machines.
What a clear and informative video. You are awesome!
This was so helpful!! Thank you and it was truly fascinating.
Thank you! You explained well with examples...
Great video Ben. I see the SEM is working nicely.
Btw, Mike from mikeselectricstuff is them man. You two are star content producers. Very underrated.
Very informative, even 5years later. Thank you.
Now this is what I love to hear :) Thanks for the info! Now I know what to look for my next projector :) Cheers!
great video - very informative. well spoken.
Amazing video. Thanks for helping me understand this technology!
Great video Ben!
Very cool, I never thought about the binary nature of DLP's and how to get variable brightness from them, thank's for the info.
It's funny you put this out today, I just mentioned the rainbow effect you get from DLP like illumination in LED flat bed scanners in my last video but I filmed it months ago.
Really enjoyed watching every second of this! It’s amazing what these DLP chips do. That Dell projector was my first DLP! It’s fascinating the similarities to camera sensors and I wonder why they don’t use tiny color filters over slightly smaller mirrors to actually make individual RGB pixels instead of using a color wheel. Our current projector does 3D and it’s interesting how that work as these tiny mirrors are in sync with the shutter glasses. Sometimes I do see the rainbow effect from the color wheel but it doesn’t bother me much. 😄
Fascinating stuff Ben - thank you.
Brilliantly explained..thanks and keep it up😀👍
Great video. And Mike..... is everywhere!!!
Very impressive. Thanks for sharing !
ONE OF THE BEST VIDEOS ABOUT ( DLP) SEE
Thank you for this amazing demo
This is awesome! I kinda fancy having a go at making the macro scale one. Would love to see what you make of it
I owned a DLP rear projection TV that I kept 9 years and it never lost any pixels. The little mirrors really do last.
Excellent presentation.. thanks for the time.
Thank you very much that was extremely interesting and has given me great insight into DLP technology
VERYY GOOD INFORMATIVE VIDEO, KEEP IT UP MAN....
This was a great explanation
The best channel in the world!!!
You would make a very good teacher.
Nice video.
Every time I think about DLP and moving mirrors I think about the sound they make. But well, they move so fast, and they are only 10um in size that I do not think they make any real sound...
I think having macro-DLP working would be cool. Even monochromatic one!
this video is very well made, thank you!
Amazing explanation. Thanks for sharing! :)
Really, extremely, fully usefulllll! God bless you and everyone! An interesting way to explain and very clear! Thank you so much!
Wow, now I'm in the interesting part of youtube. Awesome channel, awesome videos! Thank you!
i never seen exploration like this thank you sir
dude! absolutely love your channel. thank you so much for sharing
Thank you...great description