Subject: Re: cheap-shit laser displays From: Danny Ayers <danny.ay...@gmail.com> To: Kragen Javier Sitaker <kra...@canonical.org> Cc: kragen-...@canonical.org
On 8 July 2010 09:37, Kragen Javier Sitaker <kra...@canonical.org> wrote: > 12kHz is a horizontal scan on a 320×200 60Hz-refresh display; 28.8kHz > is a horizontal scan on a 640×480 60Hz-refresh display. The > newly-fashionable 16:9 aspect ratio gives you more screen space than > 4:3 for the same number of horizontal scans; 1024×600 is the same > number of pixels as 900×680, but at a 12% lower horizontal scanning > frequency. You could carry this much further, e.g. with a 8:3 or 16:3 > aspect ratio. > > The cones of cheap dynamic earphones can move hundreds of microns at, > I hope, tens of kilohertz. I would imagine so - many earphones can give reasonable response at 10kHz+. My guess though is that the deflection would be significantly non-linear. There should also be some advantage here in driving the scan with a sine wave, I believe it would reduce the 'bounce' of overtones a sawtooth would create. Although it may turn out to be straightforward to compensate for non-linearity using analog and/or physical components, I suspect there may be advantages in doing a lot of this this digitally. For example, a crude (but fastish) 1 bit D/A converter followed by an analog resonant filter, with extra damping on the moving parts might be combinable to provide an accurate scan curve. Cheers, Danny. -- http://danny.ayers.name -- To unsubscribe: http://lists.canonical.org/mailman/listinfo/kragen-discuss
