Introduction: Privacy Monitor Hacked From an Old LCD Monitor

Picture of Privacy Monitor Hacked From an Old LCD Monitor

Finally you can do something with that old LCD monitor you have in the garage.
You can turn it into a privacy monitor! It looks all white to everybody except you, because you are wearing "magic" glasses!
All you really have tohave is a pair of old glasses, x-acto knife or a box cutter and some solvent (paint thinner)

Here is what I used:
an LCD monitor of course
single use 3D glasses from the movie theater (old sunglasses are just fine)
paint thinner (or some other solvent such as toluene, turpentine, acetone, methyl acetate, ethyl acetate etc)
box cutter (and CNC laser cutter :) but that you don't really need, I'm sure x-acto knife and a steady hand would do just fine)
screwdriver or a drill
paper towels

Step 1: Take the Monitor Apart

Picture of Take the Monitor Apart

Find an old monitor that you are willing to sacrifice.
Take off the plastic frame by unscrewing all screws from the back.

Step 2: Cut the Polarized Film

Picture of Cut the Polarized Film

Most LCD monitors have two films on the glass - a polarized one to filter out the light you are not supposed to see, and a frosted anti-glare film. The anti-glare film we don't need, the polarized one we do - it is used for the glasses. 

So, grab you cutting tool and cut the films along the edge. Don't be afraid to press, metal wont scratch the glass, unless there is sand or other abrasives on it.

Then, start peeling. Make sure to save the polarized film, also remember the orientation.

Step 3: Clean the Film Adhesive

Picture of Clean the Film Adhesive

After you remove the film, the glue will likely remain stuck to the glass, so here comes the messy part.
With some solvent, soften the glue and wipe it off with paper towels.
I started with OOPS, but that was not fast enough so I got some paint thinner.
I found out that if you cover the screen with paper towels and then soak them in paint thinner you can let it sit longer and dissolve the adhesive without running and evaporating.
Scrape off the soft glue with a piece of plastic or wood.
Be careful not to get paint thinner on the plastic frame, because it will dissolve it.

Step 4: Monitor - Done

Picture of Monitor - Done

After cleaning the adhesive, assemble everything back the way it was. Before even making the glasses, you can test the monitor with the polarized film!
Notice how the upper left corner looks clear, because it has the anti-glare film removed. That is the part we are going to use to make the glasses.

Step 5: Pop the Lenses Out

Picture of Pop the Lenses Out

For the glasses, I used single use 3D glasses from the movie theater, but you can use whatever you want.
Pop out the lenses or take the glasses apart if you can.

Step 6: Scan, Trace, Cut

Picture of Scan, Trace, Cut

If you are going to use a cnc blade or laser cutter, scan and trace the parts.
You can find a local vinyl or laser cutting service, or you could send them to an online service like
I scanned the frames so I can use them as a reference for the lens orientation.
Remember, this is a polarized film so the angle is critical. Back and front also matters.
If you don't have access to a cnc cutter or you don't want to wait for an online service, you can probably tape the old lenses on the film and then cut them out with an x-acto knife.

Step 7: Reassemble Glasses and Enjoy!

Picture of Reassemble Glasses and Enjoy!

Finally assemble the glasses and you are ready for some fun!
People might think you are crazy, staring at a blank white screen wearing sunglasses!
But I guess that makes it even more fun!


Legsmaniac (author)2018-01-17

Is there a way to make this screen look like it's off (ie black screen) to non-glasses wearers? A bright glaring white screen is a bit off-putting to onlookers,

ChrisM371 (author)2016-05-29

I think this needs 1 more hack to be really useful.
We need to figure out a way to feature an image on the white screen that gets filtered out by the glasses.
For instance, if instead of a white screen, anybody without glasses who walked into your office would see a spreadsheet, but with the glasses you wouldn't see the spreadsheet.
Too complex, or is it a possibility?

Print a full screenshot of the spreadsheet and taskbar onto a piece of thin, clear plastic. Convince people you can only see well with black and white, so you can make it a real high contrast print. But make sure any lines are thin. Apply this to the LCD, taking care to remove bubbles. Tehn jsut get uesd to seneig waht it looks lkie knid of srecwed up. The brain is amazing at adapting, and there is a good chance you read the last sentence naturally. Look again ^^.

XD do you read Cambridge research? If you raed any setcnene with the lteetrs gnoe arwy, tehn you can sltil raed it if the frist and lsat ltteres are in the smae palce as bofere.

Nveer raed Cabmidrge Rseaerch brefoe, but I saw tihs smoehwree and hvae uesd it to dmeontrstae my piont a few tmies.

Yea, it is pterty good at gtnietg a pnoit arcsos

S200 (author)RogerD52017-04-20

Good at getting a 'Pinot' across...?/

Good-Oh! :D

StephanoH (author)S2002017-10-14

Are you guys takling 'buot wine?

ashery (author)RogerD52016-06-07

I know that but you cant read this:

sw y cy pe on ts we.

RogerD5 (author)ashery2016-06-07

Full words please. Then I will translate it.

Wow that's actually not bad. Might work.

The brightness would have to be kept low as well to avoid drowning out the image of the spreadsheet with light.

Di Immortales (author)ChrisM3712016-06-07

That is a great idea, although i don't believe it can be done. You could maybe put a standing image, but then that would conflict with the image on the screen

BettyP3 (author)ChrisM3712016-05-29

Won't work. The crystals in a Liquid Crystal Display polarize the light to one direction or another, depending on their orientation, but doesn't actually block light. But when that polarized light shines through a polarized light filter (the film or glasses), it shows black or white depending on the orientation of the crystals or the filters. Without the polarized filter it's not possible for any image to be seen. The film he removed is a polarized light filter. So basically, he transferred the function it does from the screen, to the glasses. No matter were you place the filter, it will still polarize the light.

AdityaY1 (author)2016-12-21

Would taking out the polarising film interfere with the touch screen function of an smartphone?

MihajloP (author)AdityaY12017-01-24


AdityaY1 (author)2016-12-21

Can I do the same for my Micromax smartphone touch screen? Plz reply

rajendra.raju.94402343 (author)2015-01-09

can it work tft moniter

yes it works for all LCD, cellphones and LED's. and TFT screen too. I did in my child hood with small "digital calculator". None of my friend could use my calculator, But was master then in making calculations using the same calculator

BettyP3 (author)mfarooqi2016-05-29

It WILL NOT work on LEDs, TFTs, oLEDs, CRTs, or DLPs. It has to be an
LCD screen (Liquid Crystal Display), because the crystals work with
polarized light & a polarized light filter (the film).

tincupchalice (author)BettyP32016-05-30

Come on. TFT and LED are both LCD.

GerardoF10 (author)tincupchalice2016-12-14

LED backlight refers to an LCD, but OLED is organic LED. This is not LCD technology. An OLED screen is a matrix of millions of pixelwide LCD.

BettyP3 (author)tincupchalice2016-05-30

I take apart & fix this kind of stuff all the time for a living. An LCD monitor or TV may have an LED backlight these days instead of the older florescent backlighting of a few years ago, but it's still an LCD display, regardless of what kind of light is behind the display. A true LED, oLED, & TFT display does not use liquid crystals found in LCD displays & do not have a backlight behind the screen. They use a different technology entirely, so polarizing the light or using a polarized light filter wont make any difference. With oLED, LED, & TFT, displays, every pixel is a tiny LED that gives off it's own light & color. With LCD displays, the crystals & the polarized light filer, allow or block the light to shine through from a light source behind the screen. This will only work with LCD technology, don't ruin your oLED or LED screen just because some troll here likes to see people destroy their screens. Believe me, it won't work unless you have an LCD screen. If your screen is backlit by LEDS, it's still an LCD screen, not an LED screen, regardless of what the sales people said when you bought it. Likewise, don't screw with a plasma TV either. They don't use LCDs or have a backlight either. Just like true LED displays, each pixel is it's own light source, & there is no backlighting or polarizing.

ToaH (author)BettyP32016-09-22

Thank you for the reminder. Do you know how to tell the difference when looking at a monitor? There is a university surplus store that I hope to get a monitor from, but they don't label the monitors for sale

BettyP3 (author)ToaH2016-09-25

If it's fluorescent backlit, it's heavier than LED backlit. If it's 6 or more years old, it most likely is fluorescent backlit. All newer LCD displays are LED backlit.

Both types function the same & use polarized light, but the LED backlit ones use low voltage LEDs behind the screen, & the other uses high voltage thin fluorescent tubes behind the screen. When they get old or burn out, it is much easier to replace the LEDs & their power supply, than the fluorescent ones.

In theory, LEDs should last longer, but due to poor modern designs, crappy power supplies, over-pushing LEDs to or beyond their limits, & short-lived Chinese capacitors, you'll find in practice, most of them don't last very long at all, or grow dim in a few years.

IF it's an OLED display or plasma display, it will be 3-10 times more expensive than LCD displays. OLED & plasma displays won't change color, or loose contrast when viewing them off to the side like LCD panels do. but newer or better LCD panels don't do it as much as the older ones. Also plasma displays will be very heavy, & a bit thicker than other types except the very old style CRT (picture tube) displays.

adcurtin (author)BettyP32016-06-10

Nope, still wrong, sorry. TFT is a type of LCD screen. LED typically means LED backlit LCD (but is a terrible name). Both of which will work with this. I have _never_ seen LED screen refer to anything other than LED backlit LCD (well, for monitors at least).

OLED (the O is capital) will not work, and is the only display type you listed that every pixel is actually an LED itself.

if you want to provide a source saying otherwise, I might believe you, but right now, you're wrong.

static (author)adcurtin2016-06-24

I really don't know who is correct, but respectfully I was left with LOL when you demanded the party you challenged to supply supporting references, when you supplied none in your original challenge comment.. I suppose one shouldn't expect reliable informative comments in many internet comment sections

healthy_smoothies (author)static2016-07-24

hahahah so true!

adcurtin (author)static2016-06-25

spend 1 minute googling the things I said and the things she said. you'll easily find sources that back up some of the claims, and you won't find sources for other claims. Take a guess which category the source I was asking for falls under…

atgm (author)tincupchalice2016-05-30

LED as light source for an LCD display - yes, it will work.

Straight LED display (e.g. organic LED, old 8 segment calculator LED display or the other technologies Betty P3 listed) it will not work because those displays do not use polarized light.

mrdoc2 (author)2016-11-08

I fucked up monitor. I did everything; but I can't remove the glue and I the monitor is not clear when I look through the polarizing filter. I removed the anti-glare from the polarizing filter and then I cant see like the words. Is it becuase of the glue? How the heck do I remove it I used everything.

TikshanB (author)2016-10-14

Which type of polarzied glass used for sunglasses.How can i buy glass .online many types of polarized glass are available

TikshanB (author)2016-10-14

How can i buy online many types of polarized glasd is available

TikshanB (author)2016-10-14

Which type of polarzied glass used for sunglasses

JohnA71 made it! (author)2016-09-18

It worked. Sharing only the newbie headaches I learned.

1. LCD or LED. My LCD Monitor, like many, has an LCD screen, but is backlit (the white light behind the LCD screen) was LED. If you remove the LCD screen and reassemble monitor, you simply have a monitor shaped night lite.

2. This does not take brains. It takes time and patience. I spent 2-3 hours removing the filter from the LCD screen. Start the cutting with and exacto knife and once you have the edge lifting up from the LCD screen, use a blunt, flat-head screwdriver to slowly separate the filter from the glue holding it to the LCD screen. I can not stress this enough. Go slow and make small strokes to separate the filter from the glue on the screen.

3. Acetone worked nicely to remove the glue from the monitor. It warped my filter I took hours prying off. Only suggestion, re-read the author's instruction and follow it to a tee.

4. If you have separated the filter from the screen and are testing the visual aspect of seeing thru the filter, if you only have a clear picture when you are next to the monitor, I found I needed to separate the filter again. Turns out I scraped both sheets off the LCD monitor initially, resulting in only seeing the visual when really up close. Removing or separating the filter from the other layer did the trick. It, too, takes time.

5. Don't rush. I did and burned thru multiple monitors taking shortcuts or hurrying thru the filter removal. Ripping the filter when trying to peel it off the LCD screen was the biggest offender.

FaceInCake7. (author)2016-06-08

I find that the 3D glasses I got already filter the light, I can see the screen... If I tilt my head sideways. :P

But I have a problem. all these images show clear images, or minimal blur. The screen is really blurry for me unless the polarizing filter is right up against the screen.

Can anyone help me on this?

dls3491 (author)2016-06-06

if you used round frame sunglasses you could adjust polarization

RogerD5 (author)2016-06-01

Well, in a sense you are right. However, what we were talking about was pure steel. Steel CANNOT scratch glass. You were talking about alloys, not steel. Point taken, a utility knife can scratch glass though. Also, you mentioned Chromium being added. That was a little ignorant seeing as Molybdenum and Carbon are the real ones that do the job. And a buck knife having vanadium, well, you mentioned the toughness of vanadium. So you mean that your buck knife is pure metal spermicide? Interesting thought. You're arguing with a chemist.

ashery (author)RogerD52016-06-02

Yay, finally, someone who's found a use for my memorising the periodic table.

RogerD5 (author)ashery2016-06-02

The periodic table has a lot of secrets. Check out nitrogen. It will not only suffocate you due to lack of oxygen but also steal your reserve oxygen supplies, so an ordinary person will die in about 1-2 seconds of breathing in. It will feel normal too, because your body only checks that you breathe in air, and breathe out CO2. Also, thanks MH9 and ashery.

dgateley (author)RogerD52016-06-04

O.T. So why isn't it used in gas chambers?

RogerD5 (author)dgateley2016-06-04

Am I a forensic chemist? No. I really have no idea. Maybe there are chemicals that kill faster, or maybe they want their death row to suffer first. I have no idea.

RogerD5 (author)RogerD52016-06-04

I do know most gas chambers use hydrogen cyanide, which literally suffocates a person, better than water or a wet towel. However, nitrogen asphyxiation has been avoided twice, although more accurately postponed. Maybe the government wouldn't want to take that chance.

MH9 (author)RogerD52016-06-02

I like this chemist....

DarylM15 (author)2016-05-31

Does anyone know if this is possible with a laptop screen?

dgateley (author)DarylM152016-06-04

It needs be a laptop with an LCD screen. My initial hunt to find such a thing came up empty but if one is found I'll bet I can do it and probably will.

RogerD5 (author)DarylM152016-05-31

I don't suggest you sacrifice a laptop. I will work, but its better an old monitor so that if anything goes wrong, its just a sacrifice for curiousity rather than sacrificing a laptop.

LogernH (author)2015-01-31

Can you use polarized sunglasses instead of putting the polarized film in the glasses?

ShawnS31 (author)LogernH2015-10-27

I would really like to know as well. I have polarized sunglasses that I'd rather use than go through the trouble of making some. But also, it would mean that others with polarized glasses could also see your monitor.

AnishM14 (author)ShawnS312016-05-29

it depends on the orientation. it will work only if your glasses coincidentally have the same orientation as the polarized film of the monitor.

About This Instructable




Bio: I'm an electrical engineer interested in making stuff!
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