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Speaker 1: Welcome to Brain staff front house, Stuff works dot Com

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Speaker 1: where smart happens. Hi Am Marshall Brain with today's question,

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Speaker 1: what are motion cards and how do they work? Motion

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Speaker 1: cards are appearing everywhere these days. You can see them

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Speaker 1: on book covers, on DVD cases, even sometimes on boxes

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Speaker 1: of cereal. They've been around for a long time, but

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Speaker 1: lately they've increased dramatically in the number of images on

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Speaker 1: a card. Early versions only had two or three images,

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Speaker 1: but the new ones can hold enough images to simulate

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Speaker 1: a couple of seconds of video. Motion cards use a

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Speaker 1: special technology called lenticular printing. This process takes a batch

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Speaker 1: of images and prints alternating strips of each image on

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Speaker 1: the back of a transparent plastic sheet. The plastic sheet

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Speaker 1: has a series of curved ridges and bosston on it.

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Speaker 1: Each curved ridge is a lenticule. Each lenticule is approximately

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Speaker 1: point three millimeters wide. You can see them if you

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Speaker 1: look really closely at the motion card, and you can

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Speaker 1: also feel the ridges made by the lenticules. If you

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Speaker 1: can get a magnifying glass and get up next to

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Speaker 1: the edge of the card, you can actually see that

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Speaker 1: each one makes a little curved lens. When light passes

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Speaker 1: through the plastic sheet. It's reflected from smooth white paper

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Speaker 1: under the plastic sheet, and the returning light passes through

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Speaker 1: the image strips printed on the plastic sheet. The lenticule

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Speaker 1: is made in such a way that it refracts the

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Speaker 1: returning light at a specific angle and it magnifies the image.

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Speaker 1: The strips are aligned so that all the strips for

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Speaker 1: a particular image are reflected at the same angle. Because

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Speaker 1: of the refraction and the magnification, what you see is

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Speaker 1: a single complete image that appears to cover the entire card.

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Speaker 1: As you change the angle of the card in relation

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Speaker 1: to your line of sight, you see the different image

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Speaker 1: strips as a series of complete images. The whole thing

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Speaker 1: with motion cards started decades ago, but the printing and

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Speaker 1: alignment technologies of the time really only allowed two images

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Speaker 1: in the card. Today, with much higher resolution printing possible

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Speaker 1: and better lens manufacturing alignment, they can fit in ten

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Speaker 1: or more images. It's possible to get the alignment so

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Speaker 1: close now that it's possible to put a different image

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Speaker 1: into each eye because of their different viewing angles, and

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Speaker 1: this lets them create a three D kind of effect

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Speaker 1: with motion cards. For more on this, and thousands of

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Speaker 1: other topics because it how staff works. Dot com