Hi! I've been thinking about HMDs lately. What's the cheapest possible way of making the smallest possible graphical display? I've got this idea, it could be bad, but let's go: Build some kind of a fast, tiny rotating device, allowing for rotation in both horizontal and vertical directions, directed by two currents (an X current, and a Y current). Put a very small, but focused light source on the front of the device (could be a led with a lens or something). Make electronics that controls the rotating device to steadidly increase the X voltage to the maximum, then increase the Y voltage one "step", and decrease the X voltage down to the minimum again. Repeat this until the max Y voltage has been reached, then reverse the process by decreasing the Y voltage instead of increasing it. At the same time as doing this, get the driving electronics to load values from a buffer, setting the focused light source to that value (a led has approx 2 volts max, so 0-255 will turn into 0-2 volts). Aim this construction against a partially transparent surface (could be very thin white paper). Voila! You have a television screen using lights instead of a catode cannon, and a piece of paper instead of a phosphor surface. Of course, this way of doing it would cause some vibration, but it may be worth a try. Only one problem: What would this rotating device be? Another display device, that'll cause less vibration: First, put a reasonably strong light source behind a surface that'll blur and spread the light. Then get a motor, and make a disk with holes going towards the center in a spiral. Make an extra hole on the disk, and put a sensor detecting if something is in the way of an IR light "over" the disk, so one pulse will be generated for each disk rotation. Put the light behind the disk. Make some electronics that'll load pixels from a RAM buffer into the light source as in the previous paragraph, and you've got yourself a screen. Another problem: You need to convert from linear coordinates to circular coordinates. BTW: If you recognize the disk display, it's actually a quite old invention. The first TV was made that way. ;) -- Thor`n -- Subcription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" toWear-Hard Mailing List Archive (searchable): http://wearables.blu.org
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