Automated Fixtures - Vl 3500s shutter mechanism???

[photoatdv]

Okay so I saw a show last night that had VL3500's. I was talking to the lighting guys and they were talking about the shutters (which they used extensively). I know that it's a 4 blade shutter like on a leko, but it can rotate and change angle.

How exactly does this work? I found the VL3500 service manual, but still can't find much about it. I'm kinda confused about the multiple planes going on there. And yes, I am a geek :-).

And is the shutter mechanism the reason for the longer head? It looked really long (they were up on a truss so I couldn't see them very closely).

[Jby007]

Taken from the spec sheet


The fixture’s shutter mechanism is comprised of four frame blades that move
independently or in unison on two planes for a crisp, sharp image. The entire
assembly operates in a smooth, time-continuous motion using stepper motors
(two per frame blade and one for the entire mechanism). The shutter mechanism
can rotate 50° in either direction and the frame blades can tilt +/- 30°.

[derekleffew]

Originally Posted by photoatdv

...And is the shutter mechanism the reason for the longer head? It looked really long (they were up on a truss so I couldn't see them very closely).

Longer head than what? The VL3000Spot, VL3000Wash, and VL3500Spot all share the exact same dimensions, and appear identical from the outside. The VL3500Wash has a larger diameter lens. [Similarly, the MAC2000Profile (no shutters) and MAC2000Performance (with shutters) also look identical.]

The shutter channels for the VL3500Spot are:
CH Parameter Range
18 Shutter 1a 0 (open) - 255 (closed)
19 Shutter 1b 1 (open) - 255 (closed)
20 Shutter 2a 2 (open) - 255 (closed)
21 Shutter 2b 3 (open) - 255 (closed)
22 Shutter 3a 4 (open) - 255 (closed)
23 Shutter 3b 5 (open) - 255 (closed)
24 Shutter 4a 6 (open) - 255 (closed)
25 Shutter 4b 7 (open) - 255 (closed)
26 Rotation 0 - 255 (128 - center)

Thus a channel controls each end of each of the four blades; and channel 26 rotates the entire assembly, just like rotating the barrel on a SourceFour.

As for the "plane" thing: ideally one would want each shutter to be in its own plane, but this leads to issues with being able to achieve a sharp focus on all four shutters, so Vari-lite, like many ERS manufacturers, puts opposing shutters in the same plane.

[photoatdv]

I was more referring to how does it work mechanically. I'm confused about how the shutters are able to both move and change angles. I'm figuring the rotation is accomplished by having the whole framing mechanism rotate.

JD, or porkchop, or any of out other ML techs, anyone know?

Thanks Guys!

[derekleffew]

Perhaps this illustration, from http://www.vari-lite.com/clientuploa...500_User_0.pdf, plus an explanation, will illuminate.

(Looking at the larger drawing; ignore the smaller "Motor Side" drawing for now.) Frame Blades 1 and 3 are shown in their extreme closed position. The arm attached to Frame 1A motor moves CCW (left) to open the right-hand end of Blade 1 as the roller moves in the slot. The arm attached to Frame 1B motor moves CW (right) to open the other end of Blade 1 as the roller moves in that slot. To keep the blade square and not angled, both 1A and 1B must move the same distance at the same speed.

This is but one of many methods to achieve a linear action from a rotary motor. Most others use gears, which I believe is how Martin does it in the MAC2000Performance (certainly for the color mixing flags, except toothed belts instead of rack gears):

VEX Robotics Advanced Gear Kit


Hope this helps.

[photoatdv]

Yes, that does help !

When I was told that the shutter blades angles 30', I was thinking they meant towards or away from the lamp. Opps...

This does make sense. Though if I hadn't been on about an 18 hour day by the time I saw these and realize what the tech meant... I probably still would have asked how it worked. I really am too much of a geek sometimes... I always want to know how and why the gear works, not just how to use it.

[derekleffew]

Originally Posted by photoatdv

... I always want to know how and why the gear works, not just how to use it.

Be sure to put Automated Lighting, by Richard Cadena (There's a SECOND Edition? Already?!) on your holiday wish list.