How Digital Light Processing (DLP) works----make money online

today on Applied Science I'd like to

talk about how digital white projectors

work and so to demonstrate this I made a

macro scale digital mirror chip which

we'll have some fun with and then also

we'll zoom way in and check out what an

actual DLP chip looks like under the

scanning electron microscope okay so

let's get started

almost all projectors work on the same

basic principle you start with a light

source you filter the light source based

on the image data that you want to

display and then you use a lens to

transfer that image from within the

projector out to a projection screen so

in a film projector it's pretty

straightforward we've got our light

source you pass the film in front of it

and then you use a lens to transfer that

image to the screen and in an LCD

digital projector we'd have basically

the same thing but the plane of the film

is replaced with a liquid crystal which

allows the light through in certain

areas and not in other areas so we have

pixels that are clear and pixels that

are opaque one problem with liquid

crystal display projectors is that you

sometimes need three separate LCDs for

the colors red green and blue and this

complicates the optical path quite a bit

because you have to combine those three

colored optical paths back into one this

dlp projector gets around the problem of

requiring three separate light paths

like a lot of LCD projectors do and so

it's cheaper and has better performance

characteristics in some areas so let me

show you what's inside this thing we

have a bulb and this is a high intensity

discharge bulb like a mercury vapour

lamp and then a lens to get the light in

a nice column from this light bulb as

normally it's just spraying out in all

directions but we want to have a column

of light on this special DMD device in

DMD stands for digital micromirror

device I should note that DLP stands for

digital light processing which is a

trademarked name kind of like Xerox it's

become very common way to describe this

but that's actually a trademark name

owned by Texas Instruments and the

digital mirror device is an array of

tiny mirrors and when the mirror is

facing in the right direction it shines

light through our main projection lens

and then it forms an image out on the

projection screen here so it's basically

the same thing as an L

CD and but instead of the pixels being

clear or opaque the pixels are either a

mirror that's turned in the right

direction to shine light through this or

their turn to ways that the light

doesn't shine through the lens I owe a

big thanks to Mike's electric stuff for

donating this DLP chip to my channel

here and I cracked it open this is

actually what the case looks like and I

opened it up which took quite a bit of

doing originally I thought that the case

was soldered shut but it's actually been

welded and so I ended up using a dremel

just to grind away the casing here and

opened it up and this is what the chip

actually looks like so as you can see it

just looks like continuous mirror but

actually there's many many thousands of

tiny little mirrors that represent one

pixel each on the surface here so to get

of under understanding of how this works

I made a macro scale model so let's take

a look at that this is a model of the

digital micromirror device that's in the

projector and as you can see it's built

with a whole bunch of individual mirrors

and just like in the real DMD chip each

mirror has its own little hinge and so I

built this by starting with a plastic

grid and hot gluing down some thread

across the grid openings and then I cut

out a whole bunch of small mirrors from

a piece of mirrored acrylic and glued

those down with a washer on the back and

the original plan was to make tiny

little magnets electromagnets at winding

them on my lathe and then putting an

electromagnet behind each mirror and so

then I could move the mirror with an

electromagnet and I did actually get

this working it drew about 300 milliamps

I think at at 3 volts or so to get the

mirror to move however I scaled up the

effort mentally required to do this for

you know sixteen or twenty five or

thirty six mirrors and it wasn't going

to happen today so I came out with

another way of showing this that's a

whole lot easier here's all the washers

on the back of each mirror I can affect

them all globally just by using a really

big magnet so it's true I don't have

image control originally I was going to

have a microcontroller actually control

the electromagnet so I could generate a

primitive image with this thing which

which I might still do at some point if

I have enough time but I think this is

more than good enough to show the

concept

just keep in mind that the real digital

mirror device uses electrostatic

attraction which we'll talk about later

and I'm actually using a magnet this is

this would just be a permanent magnet

attraction just to show the thing in

motion

here's the model in action as you can

see I've got a light source set up and

it's shining on the mirror array and

then as I pass the magnet back and forth

behind the array you can see the pixels

turning on and off on the projection

screen and the trick is when the mirror

is reflecting the light through the

projection lens the image is transferred

from that array of mirrors out to the

projection screen and if the mirror is

tipped away the light just goes

scattering off in some direction that

doesn't go through the lens so

internally inside the projector there

has to be light dumped basically so the

mirror is either facing the light

directing the light out through the

projection lens or it's directing the

light into a basically a black panel

that just absorbs all that extra light

so you might be wondering how this

actually reduces the complexity from a

liquid crystal display projector like

why would we invent DLP if we already

had LCD working and also I didn't see

anything about colored light paths in

DLP if we've got the mirrors working

here like this how do we actually get

different color pixels and the answer

isn't that most DLP projectors systems

there's a color wheel that's spinning in

front of the light source so some of the

time the light is green and then they'll

also be color filters for red and blue

and sometimes even additional colors so

the trick is that we break the image up

such that when the green is when the

green filter is in place we adjust the

mirrors so that we get the green Channel

of our image and then when the color

filter rolls around to red we change the

mirrors around to display the red

Channel and if we do this quickly enough

your eye blends them all together

however you can see the separation of

colors if you're looking at a deal an

image from a DLP projector and you move

your eyes quickly by it you can actually

see the image separate into red green

blue the mirrors have to move

exceptionally fast to make this scheme

work in fact even more interestingly the

mirror is either on or off like we can't

make a pixel grey like we can with a

liquid crystal display and

lcd we can just give the pixel half

voltage and it will be semi-transparent

so we get a gray value but the mirror is

either directing light through or isn't

so the way that we get gray values with

a DLP projector is just to switch the

mirror on and off exceptionally fast the

mirrors are so small that they can move

from off to on in just you know 5 or 10

microseconds even so the chip is able to

switch the mirrors quickly enough to

make a gray level appear let's take a

close look at the DLP chip this is an

image of the chip in my standard light

microscope at the highest magnification

setting and each mirror you can make out

the grid of mirrors each mirror is about

10 microns on an edge on the order of a

red blood cell in order to get a clearer

view of the actual mirrors themselves we

need to use a scanning electron

microscope so I loaded the chip into my

SEM and got some very close-up photos of

the mirrors this region of the chip was

damaged I basically took a pair of

tweezers and just ever so lightly

touched the surface of the chip and just

the very slight amount of pressure that

the tweezers put on there just

completely blew off a few mirrors this

is good because now we can see the

suspension mechanism that actually holds

the mirror in place and allows it to

pivot back and forth and you can see

that the pivot the hinge is actually a

torsional hinge just like it is in my

macro scale model so instead of a piece

of thread it's a piece of silicon that

does the the hinging and the mirror tips

diagonally from corner to corner

remember that the force that causes the

mirror to move his electrostatic and so

the chip operates at something around 10

volts or something like that and just

the attraction from the mirror which is

held at one potential relative to the

potential of the electrodes at each

corner of the mirror is is only probably

about 10 volts or 20 at the most this

allows for very fast operation because

as soon as the voltage disappears there

is no more electrostatic attraction and

the mirror will snap back to its resting

position another drawback of LCD

projectors is that you lose half the

light right off the bat because of the

polarization filters needed to make the

liquid crystal display work now we don't

have that problem with DLP projectors

because there's no polarization necess

this means that you can get away with a

much smaller light source for a DLP

projector and then that reduces the

whole cost of the projector because you

don't need as big of a power supplier as

big of a light bulb and so on even with

the added difficulty of the color wheel

and the really high bandwidth needed to

drive the DLP chips it's still quite a

competitive display technology compared

to LCD okay hope you found that

interesting see you next time byeTop Paid Keyword :  earn cash online, google make money from home, earn money online without investment by clicking ads, free earn money website, online money making jobs, earn money online without investment by typing, online work for money, best online earning sites, make money online with google, online earning websites, money making websites, online earning websites for students,