Monocular head mounted display. I've got my beady eye on you.............................................................................................................
In 2009 I posted an Instructable on how to make a pair of glasses with a head up display to one eye, using a pair of Olympus Eye-Trek video glasses.
My reason for these projects is that I believe wearable displays will become very useful in hospital medicine, particularly anesthesiology.
UPDATE June 2014: Updated much smaller more compact version due very soon with 3D printed shell.
Since then there has been a lot of interest recently due to the current Google Glass project, which puts a head up display in front of one eye in a very neat package resembling a pair of glasses with nose-piece, top frame across over eyes, but no lenses or lens-frames.
Funnily enough monocular displays are much more expensive than binocular ones despite only having the one display as they are perceived as semi-professional devices. The military use rugged versions and also there is a big push to bring them into medical applications.
This is my attempt to make a much better version than last time, somewhat inspired by the Steve Mann Eye-Tap project and also inspired by Martin Magni who has previously hacked the video glasses I intended to use. Specifically the aims this time are:
a) Not built into a pair of glasses. Instead we have a nose-bridge to locate one end, then a springy strap runs around the back of the head to a small pad under the ear on opposite side. This arrangement is inspired by a recent concept version of the Eye-Tap (which also originally used a glasses type frame).
b) Several DIY projects out there hack a display from one side of a pair of video glasses then mount it in an arm on a glasses frame in some way, often with a lot of experimentation required to get the correct alignment with the eye. In this project, I simply keep the factory alignment of one side of the video glasses I have used.
c) As small as possible: Most video glasses blot out all forward view and light entering from above and below. I want the exact opposite, I want to wear these while doing other things, so I want to see with one eye, and with the "video" eye also be able to see in stereo if I look up or down.
Although the display looks very close to my eye, I can easily see what I am doing in stereo if I look down normally (not all the way down, just glance downwards is enough). This is the advantage of the very slim display.
Many video glasses because they are wide and block out light, can tend to have a flat circuit board running the full width of the part in front of the face. This makes hacking them to make a one-eye display not impossible but tricky.
The Myvu-Crystal glasses are great as they are essentially two displays, with a separate cable to each side, linked in centre over the nose. The quality is pretty good and yet each display is physically very small.
I have a 3D printer and original plan was to remove the electronics of the display units and embed one in a printed structure over my eye. However the more I thought about it, the more I realised that the Myvu-Crystal eyepieces look pretty good anyway, and certainly better than anything I could design and print.
The springy band around the back of the head is actually from a gaming headset which comes with a springy band with a pad on the end, a single headphone, and a small boom microphone.
With some hacking I joined the two together and made a really neat very comfortable minimalist monocular head mounted display.
Also, it comes with an i-Phone / i-Pad / i-PodTouch connector so I can download movies or TV programmes from for example BBC iPlayer, onto an i-PodTouch in my pocket and watch them on the move. If they come out with any decent augmented reality apps in the future, I can use them. Otherwise I will stick to watching films and TV.
Obviously this also might interest the wearable computing community too. Took about 3 hours to do which is vastly less than my first attempt in 2009.
What you need:
Myvu Crystal video glasses or something similar ideally with an iPodTouch / iPad type connection option:
A basic gaming headset, the sort with only one headphone on one side and a pad on the other side.
Dremel with a cutting disk or something similar.
Epoxy glue or a glue gun.
Optionally a very small nut and bolt
Step 1: Google glasses and Steve Mann Eye-Tap
I have to credit Steve Mann here of the eye-tap project, see upper part of the image:
Also, Google are working on the Google-Glass project (lower part of the image).
I did not really want to use a spectacles frame or pair of safety glasses this time around to mount the display. I found inspiration for a way to do this from an image linked to the eye-tap project..........see next page...............
Step 2: Inspiration for this project
This is a lot more like it. These images are concepts for the eye-tap.
We use the nose bridge to keep one end stable, then have a springy band arrangement around back of the head to secure other end. The outer side of the display mount runs over the ear on that side, giving another fixed anchor point.
It just might work, so now I needed a really small pair of video glasses, ideally a pair with separate cable to each display, and one that does NOT have a circuit board that runs across in front of the face of the user.
There is a pair of video glasses that fit this description: The Myvu Crystal.
Note, they make other models but this is the one I wanted.
Step 3: Step 1: Find a pair of, ideally, Myvu Crystal video glasses
Here are the Myvu Crystals. You have to search around for them. Mine were from the US.
They also come in black but I quite like the amber look.
See how slim they are. See how no electronics crosses over the nose-bridge. Ideal for what I want to do.
Step 4: Step 2: Obtain a gaming headset / microphone with just one earphone.
Any cheapo gaming headset of similar design will do. Try to get one where the shape of the side with the headphone on is wide and flattish (or could be made flat) as we are going to embed the arm of one side of the video glasses into it. Black is also best colour so matches side arm of the video glasses.
Step 5: Step 3: Cut off the ear rest
I use an abrasive cutting disc in a Dremel for all these sorts of jobs.
Cut off the arm of the video glasses on the side you want to use, about 1cm BEHIND where all the cables come in bringing the video (too far forward and you cut all the cables and ruin it).
Step 6: Step 4: Remove mic and earphone from gaming headset
Again, using gentle force, dremel etc, remove the earpiece from the gaming headset and also remove the little boom microphone. Remove all wires. We only want to keep the springy band which will go behind the head.
Step 7: Step 5: Hollow out end of the gaming headset to take eyepiece
We now want to make a groove or socket into which we will glue/bolt the shortened end of the side arm of the video glasses.
Carve away gently and try to get the shapes to match so one will neatly fit the other.
Step 8: Step 6: Hollow out end of gaming headset
Looks neat from a distance, messier close up.
Step 9: Step 7: Test fit the two main parts, tape together.
Here I have temporarily taped the two parts together so can measure it up on my head and see if it fits or not, whether too tight, too loose and so on.
Step 10: Step 8: Test fitting of two main parts
Test fitting the cut end of the arm of the video glasses into recess I have carved in side of the gaming headset springy headband.
Step 11: Step 9: Side view of two parts taped together
Looks OK. Note how headband will not go over my head but actually around behind it. The pad I want to end up below and just behind my other ear.
Note how from the side everything is in same horizontal plane. This is not quite how you need it.
Step 12: Step 10: Get correct angle before gluing everything together
Here I have rotated the two parts at the point where the end of the arm of the video glasses and the recess I carved in the end of the headband meet, until I obtained the correct angle. See now how when the display is level and horizontal in front of my face, the pad on end of the springy headband will be under and behind my ear on opposite side.
For me this seemed to work best. Probably depends to some extent on shape of your own head so experiment using tape first before you glue anything together!
Step 13: Step 11: Cut the nose bridge
Cut the nose bridge.
Be careful to cut the correct side!
We want to keep the nose support.
If you cut it in centre the metal clip that holds the nose support to the amber frame will disintegrate so cut just to the far side of this metal structure.
Step 14: Step 12: Cut nose bridge at an angle
I tried to make the angle of my cut match the angle of the metal clip that the nose supports are mounted to.
The amber plastic is actually really tough so be careful cutting it. Take it slowly.
Step 15: Step 13: Cut off the ear bud
Cut off the ear bud.
The sound through the ear buds on the Myvu is not great. If you put even a really cheap pair of earbuds directly into the headphone socket of the iPodTouch, the sound will still be miles better. We do not have the earbud on other side anyway. I want to keep stereo sound so I opted to use separate earbuds in the headphone socket of the iPodTouch.
Step 16: Step 14: Inside connection plug
Martin Magni hacked some Myvu Crystals for his wearable computing project here:
He cut all the wires to the unused video display inside the plug that goes into the little control box that comes with the Myvu Crystals.
I chickened out as was worried some of the cut ends might short out against each other and damage the whole thing.
Step 17: Step 15: Cut wires to eyepiece you do not want to use.
So, I decided to leave some cable hang out and cut it there.
I cut all the ends as far as I could to different lengths so less likely to touch each other. Also used v sharp scissors so no wire fragments hanging out of the ends of each cut wire.
Carefully taped them up.
Also means if the left display breaks one day, I could resurrect the cut right hand display, although the soldering would be a bit of nightmare on all these tiny wires, probably just about possible though.
Step 18: Step 16: All ready for final glue
Here we are. When happy with the fit to your head, check the screen is in the right place for your eye. If sure you have everything right then glue two parts together.
Note, if you push the display right up close to your eye, you can still see it and focus "long range" on it just fine. Problem then is your eyelashes hit it when you blink! Need to get it just right for you.
Also put a very small bolt through where the 2 parts of the frame are joined, BEHIND the point where the cable comes in carrying the video etc. You do not want to drill through this cable during a momentary lapse of concentration.
Step 19: Step 17: All connected up and working
This is the general setup with an iPodTouch.
The iPod goes in left hand trouser pocket.
The small box for the Myvu is actually very light but hangs at level of my waist. Does not quite reach my pocket so needs a belt clip made for it ideally.
Step 20: Attempt to show view into lens
Here is an attempt to show the display, almost impossible to get it into focus however.
Step 21: More on the gaming headset I used
This is the gaming headset I used. Only chose this one as was low price, the side of it was vaguely flat and could be cut/dremelled to make a kind of socket to take the shortened side arm of the Myvu display.
Step 22: Rear view on my head
You can see here how cable runs over left ear and down. The springy band runs across back of my head and the pad sits just under and behind my right ear.
Later on I found some black ear buds with a longer than usual cable and very carefully and neatly ran each side across the frame and headband, then wrapped the cable around the cable of the myvu so still just one single cable down to left jeans pocket.