Upgraded Raster Laser Projector Goes RGB

September 18, 2024 by Dave Rowntree 10 Comments

We’ve covered a scanning laser project by Ben Make’s Everything last year, and now he’s back with a significant update. [Ben]’s latest project now offers a higher resolution and RGB lasers. A couple of previous versions of the device used the same concept of a rotating segmented mirror synchronised to a pulsed laser diode to create scanlines. When projected onto a suitable surface, the distorted, pixelated characters looked quite funky, but there was clearly room for improvement.

More scanlines and a faster horizontal pixel rate

The previous device used slightly inclined mirrors to deflect the beam into scanlines, with one mirror per scanline limiting the vertical resolution. To improve resolution, the mirrors were replaced with identically aligned mirrors of the type used in laser printers for horizontal scanning. An off-the-shelf laser galvo was used for vertical scanning, allowing faster scanning due to its small deflection angle. This setup is quicker than then usual vector galvo application, as the smaller movements require less time to complete. Once the resolution improvement was in hand, the controller upgrade to a Teensy 4 gave more processing bandwidth than the previous Arduino and a consequent massive improvement in image clarity.

Finally, monochrome displays don’t look anywhere near as good as an RGB setup. [Ben] utilised a dedicated RGB laser setup since he had trouble sourcing the appropriate dichroic mirrors to match available lasers. This used four lasers (with two red ones) and the correct dichroic mirrors to combine each laser source into a single beam path, which was then sent to the galvo. [Ben] tried to find a DAC solution fast enough to drive the lasers for a proper colour-mixing input but ended up shelving that idea for now and sticking with direct on-off control. This resulted in a palette of just seven colours, but that’s still a lot better than monochrome.

The project’s execution is excellent, and care was taken to make it operate outdoors with a battery. Even with appropriate safety measures, you don’t really want to play with high-intensity lasers around the house!

Here’s the previous version we covered, a neat DIY laser galvo using steppers, and a much older but very cool RGB vector projector.

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Saving An Expensive Sony HW65ES Projector With Some Fresh Chips

January 2, 2024 by Maya Posch 11 Comments

When you’re the proud owner of a beast of a projector like the Sony HW65ES (£2800 in 2016), you are understandably upset when it stops working. In the case of [Wettergren] it appears that a lightning strike in the Summer of 2021 managed to take out the HDMI inputs, with no analog or other input options remaining. Although a new board with the HDMI section would cost 500 €, it couldn’t be purchased separately, and a repair shop quoted 1800 € to repair it, which would be a raw deal. So, left with the e-waste or DIY repair options, [Wettergren] chose the latter.

Suffice it to say that taking one of these large projectors apart is rather an adventure, as is extracting the input PCB. On this board some probing showed that while the HDMI 2 port showed some signs of life, with its DDC lines functioning and the EDID readable. The HDMI 1 port had a dead short on these lines, which got traced back to a dead Sil9589CTUC IC, while HDMI was connected to the Sil9679 IC next to it. With this easy part done, the trick was finding replacements for what is decidedly not an off-the-shelf component, but fortunately EBay came through. This just left the slow agony of microsoldering to replace the dead IC, which ultimately succeeded.

After the second repair attempt in May of 2022, the projector is still working in December of 2023, proving that a bit of persistence, a bit of EBay luck and a microsoldering bench with the skills to use it can bring many devices back from the brink to give them a happy second life.

Giant Demonstrator Explains How DLP Projectors Work

December 22, 2023 by Lewin Day 5 Comments

Texas Instruments developed digital mirror devices, and the subsequent digital light processing (DLP) projector, starting in the late 1980s. The technology is a wondrous and fanciful application of micro-scale electronics and optics. Most of us that have tangled with these devices have had to learn their mode of operation from diagrams and our own imagination. But what if you just built one at a large enough scale that you could see how it worked? Well, [jbumstead] did just that!

A real Digital Micromirror Device (DMD) consists of hundreds of thousands of mirrors, which would be impractical to recreate. This build settles for a simpler 5×5 array made using half-inch square mirrors. It uses solenoids to move each individual mirror between a flat and angled position to create the display. The solenoids are all under the command of an Arduino Mega which controls the overall state of the display and shows various patterns.

It’s not perfect, with the mirrors not quite matching in angles at all times, but it demonstrates the concept perfectly well. When you see it in action with light bouncing off it, you can easily understand how this could be used to make a display of many thousands of pixels in a projector arrangement. We’ve featured some other DLP hacks before, too, so dive in if you’re interested.

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Human AI Pin marketing picture. (Credting: Humane)

The AI Pin: A Smart Body Camera That Wants To Compete With Smartphones

November 11, 2023 by Maya Posch 21 Comments

Seeking to shake up the smartphone market, Humane introduced its ‘AI Pin’, which at first glance looks like someone put a very stylish body camera on their chest. There’s no display, only the 13 MP camera and some other optics visible above what turns out to be a touch panel, which is its main gesture-based input method, while it’s affixed to one’s clothing using either a magnet on the other side of the fabric, a wireless powerbank or a clip. Inside the unit you find a Qualcomm octa-core processor with 4 GB of RAM and 32 GB of eMMC storage, running a custom Android-based ‘Cosmos’ OS.

The AI Pin home screen, demonstrating why hand palms are poor projection surfaces. (Credit: Humane)

There is also a monochrome (teal) 720p laser projector built-in that provides something of a screen experience, albeit with the expectation that you use your hand (or presumably any other suitable surface) to render it visible. From the PR video it is quite clear that visibility of the projection is highly variable, with much of the text often not remotely legible, or only after some squinting. The hand-based gestures to control the UI (tilting to indicate a direction, touching thumb & index finger together to confirm) are somewhat of a novelty, though this may get tiresome after a day.

An article by [Ron Amadeo] over at Ars Technica also takes a look at the device, where the lack of an app ecosystem is pointed out, as well as the need for a mandatory internet connection (via T-Mobile). Presumably this always-on ‘feature’ is where the ‘AI’ part comes in, as the device has some voice assistant functionality, which seems to rely heavily on remote servers. As a result, this ends up being a quirky device with no third-party app support for a price tag of $700 + the $25/month for online service. Not to mention that people may look a bit odd at you walking around with a body camera-like thing on your chest that you keep rubbing and holding your hand in front of.

To be fair, it’s not often that we see something more quaint in this space come out than Google Glass, now many years ago.

Laser Projector Built From An Old Hard Drive

May 12, 2023 by Bryan Cockfield 41 Comments

Spinning hard drives are being phased out of most consumer-grade computers in favor of faster technology like solid-state drives and their various interfaces. But there’s still millions of them in circulation that will eventually get pulled from service — so what do we do with them? If you’ve got one that would otherwise be going in the garbage, they can be turned into some other interesting devices like this laser text projector.

Even the slowest drives spin at around 5000 RPM, which is perfect for this type of application. The device works by mounting twelve mirrors, each at a slightly different angle, on a drum which is spun by the drive’s motor. Bouncing a laser off of the spinning drum results in a projection of twelve horizontal lines. By rapidly switching the laser on and off depending on which mirror it’s pointing at, the length of each line can be controlled.

Thanks to persistence of vision, that allows you to show text on the surface that the laser is projected on. At speeds this high, it took [Ben] of Ben Makes Everything quite a few iterations to get it to a usable space. From sensors that were too slow to lasers not bright enough to 3D prints that were not accurate enough, he goes through the design of his build and the process in excellent detail.

After solving all of the problems including building his own constant-current laser power supply, and burning up a few laser diodes in the process, [Ben] has a laser projector capable of displaying readable text at a great distance which is also portable, running on a 12 V power supply. There are some possible areas of improvement that he notes as well, such as an unbalanced 3D printed part causing a bit of a wobble and the Arduino controller not being fast enough for more text. But it’s an impressive project nonetheless, similar to a two-mirror version we saw some time ago but with the ability to display text as well.

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No Home Cinema Is Complete Without A Motorized Projector

April 5, 2023 by Jenny List 5 Comments

In the home of the future, everything is automated. Some of us are already there, in dwellings fully tricked-out with IoT and smart home devices. But they don’t somehow look as futuristic as a home in which everything is motorized. We don’t know whether this was the intention, but we certainly get a futuristic vibe from [Sam Baker]’s home cinema projector mount. It’s no mere bracket, instead on command the projector descends from concealment in the ceiling on a custom scissor lift mechanism.

A scissor lift is a simple enough mechanism, but since he was 3D printing one that had to withstand the weight of the projector, it took him a while to get it right. Even the lead screw which drives it is also printed, turned by a stepper motor. As the brains of the unit needn’t be particularly accomplished, an Arduino Nano does the job well enough.

It’s fair to say that his projector isn’t the heaviest of models, but the result glides smoothly down from the ceiling for a perfect home cinema experience. We like it.

What’s Inside A Super-Cheap Projector? Not A Lot!

December 18, 2022 by Donald Papp 39 Comments

[Raymond Ma] has a penchant for browsing Aliexpress and purchasing curious pieces of hardware that are as high on promises as they are low on cost. This is a process he aptly sums up with his opening line of “I should have known better, but…” Luckily, these devices all get torn down and analyzed so we can each enjoy and share a little slice of disappointment.

One such item is the $30 USD YT200 mini projector, which at 320×180 is almost as low on pixels as it is on cost. Still, [Raymond] looks inside to find out if there is perhaps more hacking potential than there is image resolution.

The YT200 lacks any kind of normal video input, and the anemic 15 lumen output is brazenly branded as a feature to protect children’s eyes from excessive brightness.

Light from the single LED is collimated with some Fresnel lenses. That light passes through an LCD panel, and from there the image bounces off a mirror and through a focusing lens housed in a spiral guide. Focal adjustments are made with a small lever, and the whole assembly provides just enough friction to prevent the lens from moving out of focus on its own.

The device actually does work fairly well for what it is: a way to play a range of different media types off a connected USB storage device. As long as one is in a dark room, anyway.

[Raymond] hopes to find some alternate use for the device. Might we suggest projecting into a frosted glass globe to create a sort of spherical display? A spooky eye animation on a USB stick might pair well with that.