Flcos, DMD, and more for HMD

[kwakeham]

Hi all,

I recently stumbled onto this board and have been back and forth the last week. I'm a kind of person with numerous projects and not enough time so who know's if I'll ever build anything.

I was on digikey the other day and it looks like you can order SVGA FLCOS imagers for <100 dollars canadian. qHD (960x540) is on the way. They are non-stock but do not have any miniumum, I've yet to contact digikey. They also have 852x480 and a few others. I need to sign up to get the datasheet on these and was patiently waiting yesterday on approval from Micron. They are quite small, so for HMD use but may need some decent optics which from the sounds of it is a problem. They work like DLP micro projectors with sequenced LED's. Could have potential, simiple digital RGB interface.

I own a DLP projector and I wanted to answer a question I haven't been able to find online. If you have a light and an eye at the right angle, can you look at a DMD and see an image directly, or do you need a lense assembly and it to be projected onto something because they are mirrors (theoritically a very tiny range for the human eye to see the light). DLP projectors are dirt cheap, especially used ones with dead bulbs on ebay. I've ordered one to see, an infocus LP130 which is XGA. Postal strike means it might be a while before I get it, and figure out how to start it without a lamp. Thought I've seen videos on ebay of a russian fellow using the ballast on an approximate wattage sodium lamp I think. If anyone has already answered this I haven't found it. The size of the supporting electronics seem to be an issue as well.

I also own a 13.3" laptop and had to replace the screen. It's tiny thin and super light. I'm looking for something more immersive on driving games. what I want is head tracking with a moving screen with a decent FOV (but don't have to be totally immersive). At about 6-7 inchs the 13.3 screen seems to fit the bill and I can focus on it without too much eyestrain without needing extra optics. I would like to mount it to a motorcycle helmet and have a IMU (accelerometer / gyro) to do head tracking (a friend does this for his masters in engineering). Any thoughts? Anyone know of an 13.3" pc screen or similar sized screens that wouldn't require something like a TI TFP401A DVI interface chip to get out the digital RGB?

I appoligize in advance if I asked something that's already been answered, I searched the forums and didn't find anything but it wasn't a comprehensive search by any means.

Cheers

[cybereality]

Interesting. So you are planning on building an HMD? Are you going for mono-only or are you considering stereo options (for example with 2 screens)?

[kwakeham]

I think it depends on a few factors.

I've little experience with Stereoscopic imaging but it is attractive with the FLCOS or DMD. The larger display it's obvously less attractive from the size and weight. I saw someone use two higher res 5.6", I believe, here which does present some possibilities. Like I said, my interest is a more immersive racing situation rather than me being several feet away from a 22" LCD. If the DMD device is viewable it could prove to be interesting solution.

My plan is to do some optics research when I have the time -- to figure out what I need, but I think the consensus is that small imagers make for poor FOV, while larger (4-7") makes it hard to get optics. So my one 13.3 screen idea is obviously not stereoscopic unless using something like shutter glasses too.

Has anyone done stereoscopic with two mirrors on 45 degrees direct to larger screens?

[ShawmK]

There's a digital photo viewer currently available that uses two portable media players and a pair of mirrors. I haven't had a chance to see one "in the flesh" but people who have say the quality is excellent, and the field of view is enormous.

http://www.cyclopital3d.com/3DPhotoView ... anchor_120

[Johnny-Mnemonic]

...but people who have say the quality is excellent, and the field of view is enormous.

Looks like it's printed photo version have the same optics "Stunningly wide 47 degree field of view".
So 47 degree FOV isn't enormous, it's like in old VFX-1 helmet, or close to Fat-Shark HMD.

However it is good, I'm just curious why they didn't provide some kind of video input capabilities?

[kwakeham]

I stumbled onto that cyclopital3d viewer recently, it looks to use two 4.3" LCD's that are two PMP called alphatrion HD
http://www.chinabuye.com/ainol-v6000hdv ... ayer-white" onclick="window.open(this.href);return false;

There was an 8" 1280x768 PMP from china made mention on engadget today. Though this could still be an optics problem
http://www.engadget.com/2011/06/28/gadm ... d-for-179/" onclick="window.open(this.href);return false;

My projector is in the mail, hoping it'll be holding a line low from the bulb invertor to get it to start the main electronics without a lamp.

[kwakeham]

Projector came. After opening it, and shorting the output of the optocoupler on the ballast to ground the projector would keep the colour wheel spinning.

Turns out, YES you can see an image if you look directly at the DMD.... however there is a light sensor that synchronizes the hardware to the colour wheel rather than the colour wheel to the hardware. Thus without a high powered lamp it can't synchronize and I just get static B/W image (only after flashing the sensor with a LED flashlight) that is based on a single sample. So sadly I think the DMD device for direct viewing is out, as I suspected (and the controller hardware is 3 massive IC's).

Not giving up on it. Might try a High powered Cree LED to see if it can trip the sensor.