[Pete]

I've heard it said that six-element color wheels are 50% less likely to have rainbow artifacts. does anyone know why this is so?

 

[kmartin]

I talked to a DWIN rep who was demoing the Transvision at a local A/V shop this past Thursday and asked him that very question. He said that a six segment (RGBRGB) color wheel would most likely decrease the amount of time and distance any given color was away from intersecting with the light path and therefore reduce the latency that contributes to producing the effect. It sounded reasonable, but I don't think it takes into account all the variables that produce the effect (i.e. - brightness, the accuracy of the DMD in regards to reflection timing and synchronization with each color element, etc...). I remember reading on another forum that the color wheel can sometimes get misaligned, either through usage or because of a manufacturing defect, and cause further problems with the rainbow effect.

 

[JoeFloyd]

Doubling the color segments to 6 has the same effect as spinning the color wheel at twice the refresh rate.


The important thing that is being minimized here is the time between transitions of a single color. The total time a given color is project will remain about the same. The end result is that as objects move relative to the projected image the degrees of arc covered by the object while being illuminated by a single color between transitions will be reduced. The threshold of sensitivity to this single color strobe effect varies from person to person, but with reasonable amounts of motion and a six segment color wheel, the visibility of the rainbow effect will be decreased.


However, the human visual system is not a linear detector. It's more of a logarithmic system so it's likely that doubling the number of color segments will have an effect that is either very dramatic or not so dramatic depending on the physical thresholds of the retina and brain to perceive the color transitions. Based on the anecdotal evidence, it would seem likely that doubling the number of color segments will have a dramatic effect and almost completely eliminate the perceived rainbow effect for the vast majority of human population.


[This message has been edited by JoeFloyd (edited 04-29-2001).]

 

[Pete]

That makes sense. Thank you.

 

[bentsai]

Hi, just a newbie jumping in here but:


I read from one link off of some other post here that the new Plus projector soon to be released in Japan (called "Piano" or something like that? DLP 848x600 600 lumen machine) has a 4x color rate. According to the brochure, it has a 3 segment color wheel that spins at 4 times the "normal" speed. I assume this means 12 color segments per cycle, correct?


Does this mean that the DLP has to refresh 4 times faster? Does this wear out the DLP? (if there is such a thing.....) If this refreshing is not instantaneous, shouldn't that introduce noise as the refresh rate increases?


Just some lingering questions.