Ceiling clocks were a bit of a thing back in the days when clock radios were a fixture of nightstands. The idea was to project the time onto the ceiling so you’d only have to roll over onto your back and open your eyes to check the time, instead of potentially disturbing your slumber by craning your neck around to see the front of the clock.
As we recall, what sounded like a good idea was iffy in practice, with low-end optics and either weak incandescent bulbs or blazing LEDs. This nifty VFD projection clock by [Thomas Shupfs] seeks to fix those problems, and from the look of it does a pretty good job. It takes advantage of something else that fell out of favor with consumers — analog photography — by tapping into the ready supply of unwanted lenses. He paired that up with an IVL2-7/5 vacuum fluorescent display inside a 3D printed case with a cone-shaped extension to hold the lens at the right distance above the display. [Thomas] says that the STM32 software only supports JSON-RPC over USB at this time, and includes a couple of Python programs with examples of how to set the time and check the accuracy of the clock.
[Thomas] compares the clock head-to-head against his old LED projection clock, as seen in the featured image above; we flipped it for a better idea of what it would look like from bed. We’ve got to say the soft blue glow of the VFD would be a lot more pleasant to wake up to than the bright red LED projection. But this soft white projection clock is nice too.
Thanks to [skymab] for the tip.
Really nice, I wonder what the focal distance from VFD to lens ended up being. Now at night staring at the ceiling, how would you know the alarm is on? I made the colons blink if ALM_ON and on steady if ALM_OFF but might add a tiny dot LED in the corner, just because I don’t want to sleep in and miss work.
The tube reminds me of the National Semiconductor MA1003 car clock module, that was a thing in the late 70’s to have in your car a VFD clock.
The distance to the VFD will be the same as the distance to the film plane of the original camera, the optics work the same forwards as backwards ;)
I have one on my bedside table — I think it’s the third one I’ve had? They’re amazingly convenient, not just because I’m so short sighted that I need the huge ceiling letters to be able to see the time. I had no idea these were considered unusual.
Are they actually good for short sighted people? I’m so short sighted I’ve always assumed I’d never be able to read it if it’s on the ceiling.
I like all of this, but I think that in this image the led is both dimmer and softer than the vfd. Plus, it’s generally agreed that for equal brightness, blue has more glare and more association with wakefulness than red.
Luckily, the greenish bluish VFD isn’t your only option; you can get other colors by putting a filter in front of it at cost of brightness. There’s ones that are natively other colors, but their life is worse. Not sure if high brightness on the durable phosphor is better than low brightness on the red or amber phosphors. I’ve not tried to go beyond using a pink filter to make it look white.
You can also get a pretty large brightness variation just by turning the aperture ring. Minimum could be between 0.6 and 1.6 percent of maximum that way, which is probably fine. Side effect is you may find your focus is slightly wrong at the brightest settings or if you want a crisp image you need to be in the middle somewhere. But it’s just large numerals so hey.
It occurs to me you could also fit the theme by mounting a color filter to the front of the camera lens. They used to be more common, maybe the same place you get the old lens will have some. If not, gel filters are easy enough to get, but still.
Expanding on spaceminions’ comment, we know (through measured melatonin studies) that blue light suppresses melatonin production (reducing our ability to sleep), so the red LED’s would be better in this way. I was thinking one of those tiny OLED displays I see everywhere would be good for this; perhaps a fixture to place over your Fitbit combined with the right app would be the least painful path (says the guy who never writes software).
Looking at the simplicity of this design has me wondering if a conical lens mount over a Raspberry Pi Zero and display hat might work for the same purpose. I’ve been looking for a good time projection display for quite a while.
Yea simple … an alarm clock that requires a SD card and a Linux os
Well, I was going to comment about the effect of blue vs red light, but two others already did, and did it better than me.
My only other comment is that the clocks I have had were always too small when projected from beside the bed – always had to have them way across the room. Then the gaps between the elements were exaggerated, making the time hard to read.
Now all you have to do is paint the ceiling with phosphor and raise the anode voltage to lightly above XRAY.
how much voltage does it need to shoot electrons through the air onto the ceiling? 🤔
Glow in the dark paint and a UV laser with galvo?
Hmm, or maybe use that zinc based GITD that discharges when longwave red or infrared hits it. You could make the whole area glow with a weak diffuse source, and then scratch out the time with the infrared part. Or just use a high power IR laser and one of those rare IR upconversion phosphors, because why not? Maybe something tenebrescent, like ‘hackmanite’ if trying to be unusual.
I was surprised to see that a slide projector lens was not used. Probably harder to find these days, compared with camera lenses, but these are large-aperture lenses optimized at full aperture, and some of them even have zoom.
“Ceiling clocks were a bit of a thing back in the days when clock radios were a fixture of nightstands.”
I bought a new one this year. I got 12 alarm clocks in my bedroom. I thought it was still normal to have alarm clocks?
Tip for anyone having a hard time to get up: there’s a free alarm app for the phone called “I can’t wake up”. It’s great. You have to play games on your phone, with memory games, math, etc. You can select which ones you want, difficulty levels etc. I didn’t make it nor do I know who makes it, I just have a very very hard time waking up and this app is really amazing.
I had to google ‘nightstands’ to find out it is a bedside table. I’d never heard that word before.