Segmented liquid crystal displays are considered quite an old and archaic display technology these days. They’re perhaps most familiar to us from their use in calculators and watches, where they still find regular application. [Joey Castillo] decided that he could get more out of these displays with a little tinkering, and rocked up to Remoticon 2021 to share his findings.
[Joey] got his start hacking on these displays via his Sensor Watch project – a board swap for the venerable Casio F-91W wristwatch, with the project now available on CrowdSupply. It kits out the 33-year-old watch design with a modern, low-power ARM Cortex M0+ microcontroller running at 32 MHz that completely revolutionizes what the watch can do. Most importantly, however, it repurposes the watches original segmented monochrome LCD.
Segment LCDs are usually small monochrome devices made out of glass, that have the benefit of using very little power in their operation. They come with a fixed layout, which cannot be changed – so they’re often designed specifically for a given purpose. A calculator will have segments laid out to display numbers, often in the usual 7-segment fashion, while a watch may add dedicated segments for displaying things like “AM,” “PM,” or “ALARM.” Continue reading “Remoticon 2021 // Joey Castillo Teaches Old LCDs New Tricks”→
The seven-segment display may be a bit prosaic after all these years, but that doesn’t mean there aren’t ways to spice it up. Coming up with a mechanical version of the typical photon-based display is a popular project, of which we’ve seen plenty of examples over the years. But this seven-segment display is quite a mechanical treat, and a unique way to flip through the digits.
With most mechanical displays, we’re used to seeing the state of each segment changed with some kind of actuator, like a solenoid or servo. [Shinsaku Hiura] decided on a sleeker design using a 3D-printed barrel carrying one cam for each segment. Each hinged segment is attached to an arm that acts as a follower, riding on its cam and flipping on or off in a set pattern. Which digit is displayed depends on the position of the barrel, which is controlled with a single servo and a pair of gears. It trades mechanical complexity for electrical simplicity and overall elegance, and as you can see from the video below, it’s pretty snappy.
We think the best part of this build is figuring out the shape of the cams. We wonder how they compare to the cam profiles in [Greg Zumwalt]’s mechanical display; it uses two separate discs with grooves, but the principle is pretty much the same.
Over the years we’ve seen many takes on the 7-segment display. Among the most interesting are the mechanical versions of what is most often an LED-based item. This week’s offering is from [John Burd], who published a very odd video showing off the clock he made. But look beyond YouTuber antics and you’ll see the stepper motors he used to turn the segments are dripping with graceful beauty. (Video, embedded below.)
Okay if you want to hear [Charlie Sheen] say “Raspberry P-eye”, this is the video for you. [John] used Cameo to get the (former?) star to talk about what was used to build the clock. Like we said, the video is weird. Let’s embrace that right away and then never talk about it again.
The thing is, the build is such a good idea. [John] went with some stepper motors you can source relatively cheaply from Ali Express and the like. Typically they’re around a buck or two each and have a couple of wings for screw mounting brackets. This builds on the segment displays we’ve seen that use hobby servos by allowing you finer control of how the segments move. Sure, the 90° rotation isn’t all that much to work with, but it will be much smoother and you can get fancy with the kinematics you choose. The only place we see room for improvement is the alignment of the segments when they are turned “off” as you can see the center segment in the video thumbnail below is not quite level. Maybe a linkage mechanism would allow for a hing mechanism that aligns more accurately while hiding the servos themselves behind the mounting plate? It’s in your hands now!
In the demo video you’ll also find some interesting test rigs built to proof out the project. One just endurance tests the mechanism, but the other two envision water-actuated segments. One pumps a hollow, transparent segment with colored liquid. The other tried to use water droplets sprayed in the air to illuminate laser segments. Both are cool and we’d like to see more of the oddball approaches which remind us of the ferrofluid clock.
Seven-segment displays have been around for a long time, and there is a seemingly endless number of ways to build them. The latest of is a mechanical seven-segment from a master of 3D printed mechanisms, [gzumwalt], and can use a single motor to cycle through all ten possible numbers.
The trick lies in a synchronized pair of rotating discs, one for the top four segments and another for the bottom three segments. Each disc has a series of concentric cam slots to drive followers that flip the red segments in and out of view. The display can cycle through all ten states in a single rotation of the discs, so the cam paths are divided in 36° increments. [gzumwalt] has shown us a completed physical version, but judging by CAD design and working prototype of a single segment, we are pretty confident it will. While it’s not shown in the design, we suspect it will be driven by a stepper motors and synchronized with a belt or intermediate gear.
Another 3D printed mechanical display we’ve seen recently is a DIY flip dot, array, which uses the same electromagnet system as the commercial versions. [gzumwalt] has a gift for designing fascinating mechanical automatons around a single motor, including an edge avoiding robot and a magnetic fridge crawler.
One thing we love here at Hackaday is when we get to track the evolution of a project over time. Seeing a project grow over time is pretty typical — scope creep is real, after all. But watching a project shrink can be a real treat too, as early versions get refined into sleeker and more elegant solutions.
This slimmed-down mechanical seven-segment display is a perfect example of that downsizing trend. When we saw [IndoorGeek]’s first vision of an electromechanical display, it was pretty chunky. Then as now, each segment is a 3D-printed piece with a magnet attached to the rear. The segments hover over solenoid coils, which when energized repel the magnet and protrude the segment, forming the desired digit. The old version used large, hand-wound coils, though, making the display pretty bulky front to back.
Version 2 of the display takes a page from [Carl Bugeja]’s playbook and replaces the wound coils with PCB coils. We’ve seen [Carl]’s coils on both rigid substrates and flex PCBs; [IndoorGeek] used plain old FR4 here. The coils occupy four layers so they have enough oomph to extend and retract each segment, and the PCB includes space for H-bridge drivers for each segment. The PCB forms the rear cover for the display, which is also considerably slimmed down for this version. What’s the same, though, is how good this display looks, especially with strong side-lighting — the shadows cast by the extended segments are striking against the plain white face of the display.
Congratulations to [IndoorGeek] on a great-looking build and a useful improvement over the original.
7-segment LED displays were revolutionary, finally providing a clear, readable and low-power numerical display solution. We’ve got plenty of other cheap display options now, but sometimes you just need the old nought-through-nine, and in a big, visible package, to boot. For those circumstances, consider whipping up a set of these 3D-printed seven-segment displays.
The build consists of a 3D printed frame, with each segment containing two WS2812B addressable LEDs. Each 7-segment assembly is then wired so they can be daisy chained, passing on data to the next digit in the chain. Paper is used to diffuse the LEDs for a smoother look, and a white 3D printed cover is printed for each digit to further spread the light and give a clean finish.
Being based on the WS2812Bs, it’s easy to drive such displays with just about any microcontroller or GPIO-equipped Linux board out there. We love big, beautiful displays – and the more artistic, the better. Video after the break.
The clock is a testament to [Ivan]’s design skills in the 3D printed space. Taking advantage of his large format printer, each segment consists of a front panel, large single-piece diffuser, LED carrier, and backing plate. There are plenty of nice touches, from the interlocking ridges between each digit, to integral printed arrows on the inside that guide installation of the LED strips. Fit and finish approaches the level of a commercial product, a reward for [Ivan]’s years of practice in the field.
Electronically, an ESP8266 runs the show, synchronizing the time over its in-built WiFi connection. Each segment contains 9 WS2812B LEDs, wired up in a single long strip that’s addressed by the microcontroller. This means that the segments can be lit up to any color of the rainbow, though [Ivan] is a man who best appreciates the look of classic red.