Edge-Lit, Thin LCD TVs Are Having Early Heat Death Issues

August 15, 2024 by Maya Posch 60 Comments

Canadian consumer goods testing site RTINGS has been subjecting 100 TVs to an accelerated TV longevity test, subjecting them so far to over 10,000 hours of on-time, equaling about six years of regular use in a US household. This test has shown a range of interesting issues and defects already, including for the OLED-based TVs. But the most recent issue which they covered is that of uniformity issues with edge-lit TVs. This translates to uneven backlighting including striping and very bright spots, which teardowns revealed to be due to warped reflector sheets, cracked light guides, and burned-out LEDs.

Excluding the 18 OLED TVs, which are now badly burnt in, over a quarter of the remaining TVs in the test suffer from uniformity issues. But things get interesting when contrasting between full-array local dimming (FALD), direct-lit (DL) and edge-lit (EL) LCD TVs. Of the EL types, 7 out of 11 (64%) have uniformity issues, with one having outright failed and others in the process of doing so. Among the FALD and DL types the issue rate here is 14 out of 71 (20%), which is still not ideal after a simulated 6 years of use but far less dramatic.

Cracks in the Samsung AU8000's Light Guide Plate (Credit: RTINGS) — Cracks in the Samsung AU8000’s Light Guide Plate (Credit: RTINGS)

As part of the RTINGS longevity test, failures and issues are investigated and a teardown for analysis, and fixing, is performed when necessary. For these uniformity issues, the EL LCD teardowns revealed burned-out LEDs in the EL LED strips, with cracks in the light-guide plate (LGP) that distributes the light, as well as warped reflector sheets. The LGPs are offset slightly with plastic standoffs to not touch the very hot LEDs, but these standoffs can melt, followed by the LGP touching the hot LEDs. With the damaged LGP, obviously the LCD backlighting will be horribly uneven.

In the LG QNED80 (2022) TV, its edge lighting LEDs were measured with a thermocouple to be running at a searing 123 °C at the maximum brightness setting. As especially HDR (high-dynamic range) content requires high brightness levels, this would thus be a more common scenario in EL TVs than one might think. As for why EL LCDs still exist since they seem to require extreme heatsinking to keep the LEDs from melting straight through the LCD? RTINGS figures it’s because EL allows for LCD TVs to be thinner, allowing them to compete with OLEDs while selling at a premium compared to even FALD LCDs.

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Home Automation Controller Uses Chalk

June 4, 2021 by Chris Lott 10 Comments

Responding to the Rethink Displays challenge of the 2021 Hackaday Prize contest, freelance design engineer [Rick Pannen] brings a retro look to his DIY home automation controller. You could be forgiven for not even realizing it is a controller at first glance. [Rick] built this using a magnetic chalk board and installed all the control electronics on the back. The main processor is a Raspberry Pi 400 running Raspian with IOBroker and Node-Red. Panel lettering and graphics are done free-hand with, you guessed it, chalk.

The controls on this panel are an eclectic hodgepodge of meters, switches, and sensors that [Rick] scored on eBay or scavenged from friends. We are curious about the simple-looking rotary dial that sends a pulse train based on the number set on the dial — this seems to have all the functionality of an old phone’s rotary dial without any of the fun.

But [Rick]’s design allows for easy changes — dare we say, it encourages them — so maybe we’ll see a salvaged rotary dial added in future revisions. Also note the indoor lighting ON/OFF switch that must be a real joy to operate. We wonder, is there any way the controls could be magnetized and moved freely around the board without permanently attaching them? Maybe an idea for version 4 or 5.

This design has a lot of possibilities, and we look forward to any upgrades or derivative versions of this unique home automation controller. Let us know in the comments below if you have any suggestions for expanding upon this idea.

Artwork Spans Fifty Years Of Display Technology

May 9, 2021 by Chris Lott 20 Comments

Swiss artist and designer [Jürg Lehni] was commissioned to create an artwork called Four Transitions which has been installed in the HeK (House of electronics Arts) in Basel. This piece visually depicts the changes in technologies used by public information displays, such as those in airports and train stations. As the title of the installation suggests, four different technologies are represented:

Flip-Dot, early 1960s, 15 each 7 x 7 modules arrayed into a 21 x 35 pixel panel
LCD, 1970s and 1980s, two each 36 x 52 modules arrayed into 52 x 76 pixel panel
LED, 2000s, six each 16 x 16 RGB modules arrayed into a 32 x 48 pixel panel
TFT, current, one 24 inch module, 1200 x 1920 pixel panel

The final work is quite striking, but equally interesting is the summary of the the design and construction process that [Jürg] provides on Twitter. We hope he expands this into a future, more detailed writeup — if only to learn about reverse engineering the 20 year old LCD controller whose designer was in retirement. His tweets also gives us a tantalizing glimpse into the software, controllers, and interconnections used to drive all these displays. There is quite a lot of interesting engineering going on in the background, and we look forward to future documentation from [Jürg].

You may recognize [Jürg] as the creator of Hektor, a graffiti output device from 2002 which we’ve referenced over the years in Hackaday. Check out the short video below of the displays in operation, and be sure to unmute the volume so you can listen to the satisfying sound of 735 flip-dots changing state. [Jürg] also gives in interview about the project in the second video below. Thanks to [Niklas Roy] for sending in the tip about this most interesting exhibition.

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Electronics For Aliens

October 6, 2015 by Nava Whiteford 79 Comments

We are surrounded by displays with “millions” of colors and hundreds of pixels per inch. With super “high fidelity” sound producing what we perceive to be realistic replicas of the real world.

Of course this is not the case, we rarely stop and think how our electronic systems have been crafted around the limitations of human perception. So to explore this issue, in this article we ask the question: “What might an alien think of human technology?”. We will assume a lifeform which senses the world around it much as we do. But has massively improved sensing abilities. In light of these abilities we will dub it the Oculako.

Let’s begin with the now mostly defunct CRT display and see what our hypothetical alien thinks of it. The video below shows a TV screen shot at 10,000 frames per second.

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