DIY Dual-Layer LCD monitor - can it match OLED??

when using a computer you may have at some point noticed that black on the display is never truly black it's a sort of hazy gray which results in images being somewhat flat and lifeless as any dark areas get washed out this of course isn't a problem for web browsing and general office tasks but it leaves a lot to be desired for anything else like gaming or watching movies now this issue actually occurs due to the way most computer screens generate an image which is by selective blocking light from an always lit backlight using an LCD panel if white is requested the LCD panel will let most of the light through but when an image is requested it will attempt to block the light at varying degrees across the panel to recreate the image when it comes to dark areas though it can't completely block all the light so some of the backlight inevitably leaks through washing out the image some displays fix this by using newer display Technologies which I'll be going into later but the problem is that they are really expensive we're talking $1,000 to $3,000 and I don't know about you guys but I wouldn't really want to spend that much just for a better looking gaming experience so is there a way we can improve things without breaking the bank maybe as I've just explained the way most computer screens work is by selectively blocking light from an always lit backlight so can't we just add an additional LCD panel in front of it to mult multiply this light blocking function well here I've got my old Gaming monitor it's nothing special it's just a full HD panel with a high refresh rate but as it's quite old now I've managed to pick up another one for cheap so let's take this one's panel out and put it in front of the original screen and see what happens the process for this starts out being fairly straightforward requiring the back panel to First be removed and any cables unclipped unfortunately things get a bit tricky when it comes to the panel itself as it is rather delicate and has been stuck in place with some kind of foam around its perimeter thankfully though using a plastic wedge helps to peel it away which finally frees the LCD panel to check that it still works I can reconnect it to the electronics and thankfully it appears to be okay and we can still see an image from it as long as it's in front of a light source but what if we place it in front of the original screen surprisingly it goes completely black it's still displaying an image as shown by this handheld light but for some reason the light from the lower screen gets entirely blocked and it will just not shine through the second panel this odd and somewhat disappointing behavior is actually a side effect of how LCD panels work as they rely on light polarization to block light and generate an image this means that both panels contain polarization layers so when one panel is placed in front they unintentionally interfere with each each other and block all light from passing through as they're not intended to be used like this so it might appear that this project has hit a bit of a dead end but thankfully that isn't the case because essentially all we have to do is disrupt the polarization between these two layers now you can actually get specialist depolarizing films that can do this but they are really hard to get so after much experimentation I've actually found that the cheapest and most effective way of doing it at home is to Simply use tracing paper as soon as the tracing paper is slid behind the top panel the image becomes visible this happens because the tracing paper causes the light to be rescattered in all directions effectively depolarizing it so that it doesn't get blocked by the second panel however here we can see our second challenge it is somewhat dim this really demonstrates the key problem with this method which is simply that it's just not that efficient because the light has to travel through two LCD panels as well as the paper so a lot is lost in the process however it is something that we can overcome with Brute Force by simply designing a much brighter backlight now the original backlight was basically just a strip of LED shining up into a sheet of acrylic which is designed to spread the light out with the help of various diffusion layers these can't be made to run any brighter without burning them up so my plan is to Simply add more of them LED strips are perfect for this as they're super cheap and can be arranged into a big grid that can be mounted behind the display another option is to use pre-made panels which were a bit quicker to wire up as you can see I've mounted mine onto some flat heat sinks which may be excessive but they will give us some more brightness Headroom if we need to drive them particularly hard as I'm really not sure how bright we need them to be yet this is just a prototype after all one issue with using LEDs in this to shine directly into the back of the LCD panel is that they produce Points of Light so to spread this out to act more like the original backlight I'm just using more tracing paper but as you can see in order for it to diffuse the light properly it needs to be several cenm away from the LEDs to hold this at the required distance it's necessary to screw and place some side panels to the back which gives us a front edge to mount a sheet of acrylic onto this serves to help to keep the tracing paper flat so essentially we've built a nice little light box this works really well to diffuse the light but how does it perform with the first LCD panel in front of it well it looks pretty good to me especially as it's not at full brightness in this shot so now it's time to add the second panel which is where the magic will hopefully start to happen this of course needs to be extracted from the second Monitor and before it gets placed on top I need to make sure that a sheet of tracing paper goes down first to act as a depolarizing filter after which the second LCD panel can be added once it's neatened up with some plastic trim it looks surprisingly okay although we're not quite done yet as we need to find somewhere to mount the rest of the electronics I've made a back plate out of a scrap piece of aluminium for this with the intention being to screw it to the original Stand this gives me somewhere to screw in place a power supply which is just a cheap enclosed type from eBay as well as somewhere to screw the original display driver boards as well as you can see there are two of these one for each LCD panel so with it all together the final thing to do is add a few precautionary fans to help to keep it all cool if necessary what a beast although it's quite thick from the front it looks pretty ordinary hopefully though its image quality will be far from ordinary so we'll test it out after a quick ad from hu hu Black Edition is a convenient and tasty way to have a nutritionally complete meal fast it's entirely plant-based with ingredients such as flax seeds pea protein and tapioca flour and for additional nutritional goodness all of this is complemented with 26 essential vitamins and minerals this makes for a high fiber high protein low carb meal that's completely free from artificial sweetness and flavorings it's super quick to prepare as well just add two scoops of it to 500 mL of water give it a good Shake and you're all set with a tasty nutritionally complete meal there are plenty of flavors to choose from and it's very coste effective as it works out to be1 186 per meal Which is less than some people pay for a morning coffee so click the link in the description if you'd like to order some hule for yourself and try it out so it's now the moment we've all been waiting for how does a DIY dual L CD monitor perform and what can it bring to the table let's find out as we've effectively got two displays to drive it's necessary to use an HDMI splitter to ensure that they get an identical signal by the way before we begin it's worth noting that using a camera to record any LCD screen results in some weird artifacts that aren't visible to the naked eye and they show up as weird hashes and rainbows there's nothing I can do about this unfortunately so try to look past it and pardon any out of focus shots which have helped to mitigate the issue anyway upon booting it up the first impression is wow that's a lot of contrast but I'm quickly distracted by text where there's a sort of weird softening to it due to the tracing paper that sits between the two panels blurring out the rear panel a bit to describe the effect is almost like adding a mild drop shadow in Photoshop but on close inspection it's actually not too far off pixel level dimming with only mild blooming showing itself on white pixels on a black background still this mostly affects office tasks which this monitor isn't really built for anyway so let's power up some games here the level of contrast that the Dual LCDs provide is strikingly obvious with dark areas of the image being Inky black and it's a night and day difference compared to a traditional LCD display activities like this is where this monitor really comes into its own and it looks incredibly rich another bonus that I wasn't anticipating is how vibrant the colors are because both LCD panels have color filters their purity is effectively multiplied two and I don't think I've ever seen such a vibrant display it's no wonder I suppose that this technique is used in professional color grading displays and it's worth noting that it's not at all like increasing the contrast setting on a TV it has instead literally increased the difference between the darkest and lightest parts of the image giving it a naturally higher cont rust ratio without having to force it so much so that it's actually quite hard to capture on camera with a standard LCD screen in shot though it makes it really obvious how well our DIY dual layer version is performing wild it's not all wonderful news however there is a major drawback power consumption the backlight alone uses over 250 watts and despite this the monitor is by no means bright it's actually dimmer than the original screens were capable of going by quite a long way which means that you can't properly appreciate HDR content for example and I think that this is the real reason why dual LCD displays haven't caught on they just aren't necessarily a good idea although looking purely at the costs to build a Dr y1 it still appears to be a compelling option assuming you have a Bas monitor already the costs break down to what's shown on screen alternative Technologies do exist though at the cheaper end of the scale you can get a backlit Zone dimming LCD display which selectively dims the brightness of the backlight over certain dark areas instead of attempting to fully block it they do suffer from an annoying level of blooming though which I personally really dislike but at least they are bright and good for office tasks too of course the ultimate display technology is OLED which has been around for years in TVs but has only recently become an option for computer monitors they have perfect black level performance as they can turn off each pixel independently if necessary but they are very expensive and can potentially suffer from image retention so it might not last as long as needed so despite its inefficiency I'm actually staggered with what we've been able to accomplish here even a few years ago this kind of image quality on any kind of computer monitor would be pretty staggering so uh that we've managed to do it DIY makes it all the more special now um I do have a few ideas as to how to make it more efficient and therefore brighter and I've posted about it on the DIY per per Forum if you do want to have a go building one yourself but other than that I'm Matt you've been watching DIY perks and I hope to see you next time goodbye for now

Channel: DIY Perks

Views: 2,363,970

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Id: ibEN9FTLdkI

Length: 12min 16sec (736 seconds)

Published: Mon Mar 13 2023