Stereoscopic 3D glasses controller
August 2010
 
This is a controller for stereoscopic 3D active shutter glasses that I have made. It is based on a ATMega8 8-bit microcontroller listening on VGA signals between computer and display screen.
Stereoscopic 3D vision is achieved by showing each eye an image of an object from it's own perspective. Active shutter glasses create that effect by showing different image to every eye in separate time periods. When left eye image is rendered on screen, right eye is blocked, and when right image is rendered left eye is blocked. If time periods are small enough, eye does not recognise blank periods of time, and both images are fused into a single three-dimensional image. An eye sees 25-30 images per second, so for the eye not to recognise blank periods, at least 60 images per second (Hz) are needed for one eye. That is, to be able to show 60 images per eye, screen needs to be able to show 120Hz.

Active shutter glasses have LCD film over each eye. The film is transparent when not powered, and become opaque when voltage is applied.

This controller powers the glasses left and right eye LCD film in correct time periods. For the controller to know when to enable left or right eye to see image, it needs to know which image is displayed on screen. Controller recognises which image is displayed on screen by listening the VGA signals between computer and display screen.

Iz3d driver is configured to show first (top) line of image in different color based on image displayed. Controller listens the vertical and horizontal timing signal and counts the image lines to skip the back porch part of the display image and when first line is display it measures voltage on red and blues signal lines of VGA signal. When red line is shown, red signal line is high and blue signal line is low, and for the blue line it is opposite. Based on the voltages of red and blue signal lines, controller puts voltage on one or the other eyes LCD film. ADC on microcontroller is used to measure voltage of red and blues signal lines.


Tags: 3d ATmega8 AVR
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