Electronically Actuated Fixed Frame Projector Screen.

 

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Here’s the base for this whole project.  I constructed this TV stand a number of months prior to the projector screen.  I had wanted the ability to place a speaker below the TV, without using the speaker itself for a stand.

The TV is held in place by what is designed as a wall mount, held up by two steel beams that I drilled out bolt holes for, and bolted into place.

The speaker , the predecessor to the one I’m utilizing now, is a Statement Center Channel, designed by the awesome guys over at speakerdesignworks.com.

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Above is the construction of the articulating arm.  Notice the bicycle bottom bracket utilized as a bearing.  I had two of these sitting around, and figured they’d be effective.  In a repeat build, I’d recommend purchasing bearings.  They’d be equivalent cost, and far less hassle.

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The solution I came up with to clamp the bearing in place.  I used a Forstner bit to bore through the entire static aspect, which was then cut in half on the saw. Once fixed to the bearing, a hole was drilled in a superior-inferior axis, which bolted the upper and lower half through the bearing.  The bearing is aluminum, so a hole through it was very easy to cut.

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Glued the whole leg together, and making a trial run of the mechanism.  What’s important here is the attachment point of the actuator.  It pulls the posterior piece of the arm downwards from the 315º position, to the 225º position.  This translates to moving the anterior aspect of the arm from the 0º position, to the 90º position.  Its operating as a reverse lever, with, as I recall, about a 4:1 force magnification.

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Here’s the two arms bolted together.

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And here they are bolted into to steel beams.

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I won’t bore anybody with images telling you how to build a projector screen.  Such information is freely available all over the interwebs.
What I will note, is that the screen material is two layers of spandex, pulled tight.  It is acoustically transparent, which works very well with the dipole design of the Statement II (the giant speakers L and R, built several months prior, and, again, plans can be found at speakerdesignworks.com).  There is minor moire effect present, but highly infrequently.  In the future I believe a material that is designed as a projector material may have incrementally better results.  For now, I’m quite happy with the design.

Other thoughts/considerations:

The plan was to create a fixed frame acoustically transparent projector screen that did not have to be attached to a wall.  This goal has been achieved.  There are limitations to the design as it stands.  If a larger screen were desired, either the entire edifice would need to be further from the wall, to accommodate the appropriate screen height.  Or a second actuator system would be necessary, upon the projector screen, which would slide it upwards as the screen rotated down.  Such a system would not be overly difficult to add to the existing design.