Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Which one is better? Platen's angle 100 or 90 degree?

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.
Gandalf
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Which one is better? Platen's angle 100 or 90 degree?

Post by Gandalf » 10 Jul 2017, 11:48

I usually made platen's angle 90 degree. But archivist model has 110 degree angle. Are there any reasots to use it? Could I know their's Strong points & Weak points? Links R ok.
Last edited by Gandalf on 10 Jul 2017, 17:49, edited 1 time in total.

Konos93a
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Re: Which one is better? Platen's angle 110 or 90 degree?

Post by Konos93a » 10 Jul 2017, 13:52

i think is 100 degree

why don't you make something that can change degrees?
the camera has to be stable but even their position can be changed .

Konos93a
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Re: Which one is better? Platen's angle 110 or 90 degree?

Post by Konos93a » 10 Jul 2017, 13:56

Image

Gandalf
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Re: Which one is better? Platen's angle 110 or 90 degree?

Post by Gandalf » 10 Jul 2017, 14:06

Thank you so much ! Excellent drawing! I like it. You are right! It's 100 degree. Sorry. After i wrote down i found i was wrong. I want to make a more simpler archivist model without CNC. So i want to know why Daniel used a platen of 100 degree angle.is it better than 90 degree? Because of More brighter?

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Re: Which one is better? Platen's angle 110 or 90 degree?

Post by cday » 10 Jul 2017, 14:34

Daniel Reetz has written about this and given his reasons for using 100 degrees, one thread found in a quick forum search may be worth reading:

Platen: Theory And Practice

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Re: Which one is better? Platen's angle 110 or 90 degree?

Post by dpc » 10 Jul 2017, 15:22

At 90 degrees the camera can see a reflection off of the adjacent platen pane. As you increase the angle between the two platen panes you can eliminate this effect. The amount you have to increase the angle depends on the field of view of the camera and this itself depends on the distance of the camera to the platen pane and the largest page size you plan to scan.

There's a trade-off worth mentioning here as you increase the platen angle between the two panes it makes the platen panes more conducive to picking up a reflection of the overhead light source. The mitigation for that is to move the light source farther away from the platen.

There is a sweet spot (perfect angle between platen planes) that ensures a minimum distance from the camera to the platen pane and a minimum distance of the light source above the platen. It's a straightforward trig exercise to calculate the various distances that the camera and light source need to be away from the platen pane (and platen 'v' gutter, respectively) and I think I've posted the formula here in the past (let me know if you can't find it).

A platen angle of 100 degrees is a pretty good number. Optimal on my scanner was closer to 101 degrees but it's difficult to get that when working with wood and by just moving the camera mount and light position an inch more away from the platen negated any problems associated with sloppy tolerances in the platen angle.

Gandalf
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Re: Which one is better? Platen's angle 100or 90 degree?

Post by Gandalf » 10 Jul 2017, 17:03

There's a trade-off worth mentioning here as you increase the platen angle between the two panes it makes the platen panes more conducive to picking up a reflection of the overhead light source. The mitigation for that is to move the light source farther away from the platen.
----------------------------------
According to your saying, is it better to use 90 degree angle because we can make a scanner shorter ( distance between platen and lamp)and save money? More farther, less lighter? Even though bigger angle can get more bright I have to move a light farther. More bright compensate will be reduced in a long distance. No difference is it right?

-----------------------------------------
There is a sweet spot (perfect angle between platen planes) that ensures a minimum distance from the camera to the platen pane and a minimum distance of the light source above the platen. It's a straightforward trig exercise to calculate the various distances that the camera and light source need to be away from the platen pane (and platen 'v' gutter, respectively) and I think I've posted the formula here in the past (let me know if you can't find it).
----------------------------------
You mean this.
https://ibb.co/h74Eua Sorry. animated gif is not working. Light glare disappears as the light is moving up.

Could you write down the link here for more my understanding please?

I think 90 degree angle more better than 100 when I read yours. Shorter distance between lamp and platen, less reflections. Am I right? I don't know why 100 is better still.

AND THANK YOU CDAY!
NO VIDEO LINK!
Anyway, Daneal said, "
Yeah, the 90 has the MAJOR advantage of being very easy to construct, which is why I chose it from the beginning. Nothing particularly wrong with going that way, but as always, we can improve... I'm not ready to recommend 100 degrees to everyone yet but I'm pretty close to saying it's ideal."

I want to know "why it is ideal". Please persuade me.
Last edited by Gandalf on 10 Jul 2017, 22:19, edited 1 time in total.

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Re: Which one is better? Platen's angle 100 or 90 degree?

Post by dpc » 10 Jul 2017, 20:08

According to your saying, is it better to use 90 degree angle because we can make a scanner shorter ( distance between platen and lamp)and save money? More farther, less lighter? Even though bigger angle can get more bright I have to move a light farther. More bright compensate will be reduced in a long distance. No difference is it right?
No, sorry if I wasn't clear. The problem with using 90 degrees is that the camera will "see" the reflected image of the adjacent plane. Daniel goes into that problem in detail in his video presentation regarding platen theory.

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Re: Which one is better? Platen's angle 100 or 90 degree?

Post by dpc » 10 Jul 2017, 20:26

Ugh. Just realized that Daniel's videos are no longer available (or it's some Adobe Flash thing that Windows 10 can't view). That would certainly make it hard for you to understand the adjacent platen pane reflection problem when using 90 degrees.

I'll see if I can come up with a few images to help explain things and post them here.

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Re: Which one is better? Platen's angle 100 or 90 degree?

Post by Gandalf » 10 Jul 2017, 21:56

dpc wrote:
10 Jul 2017, 20:08
The problem with using 90 degrees is that the camera will "see" the reflected image of the adjacent plane.
Do you mean the reflected image of the adjacent plane still show each other even at the 90 degree?

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