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

Post by Gandalf » 10 Jul 2017, 22:09

Oh. I got it. Now I understood Daniel's second video on YouTube. And I tested it on my smart phone(black screen) with wallet case. Thank you guys, konos 93a, dpc, cday. Dpc's comment was decisive to understand it. Thank you so much.

My last question, how can I show the image on this Web site when I post it?

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

Post by Konos93a » 17 Jul 2017, 10:21

i imagine in 90 degrees you need more effort to flatten the page than 100 degrees ,or the page will get fold .(but thit is gonna tell you if happen people who have 90 degrees scanner )

about reflections you can solve that with a light in a taller spot . i mean if you enlarge the distance between the middle of the glasses and the light source.

so when you capture an image you can see a lighten cycle inside the space of the glass if you have not good degrees .

to upload image go to imageupload site upload an image and then choose the link like

( https://www.imageupload.co.uk/images/20 ... G_6630.jpg )

then when you post type ([img] hhttps://www.imageupload.co.uk/images/2016/11/28/IMG_6630.jpg [/img] with one h) between the link

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

Post by jck57 » 04 Aug 2017, 12:04

Could you instead of raising the height of the light source, simply put a shade or baffle between the light source and the books so that light falls only on the pages?

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

Post by Gandalf » 04 Aug 2017, 22:59

Konos93a wrote:
17 Jul 2017, 10:21
i imagine in 90 degrees you need more effort to flatten the page than 100 degrees ,or the page will get fold .(but thit is gonna tell you if happen people who have 90 degrees scanner )

: I think 90 degree is more better to flatten the page. If you make pages even it is hard because of the book's gutter. As Daniel Reetz said on his video, 90 degree still has a reflection adjacent glass. This is main problem. But when I am editing the pages it is OK. Because the reflection is other page I can cut or remove it in a scantailer software. But someone doesn't like it. Except this one 90 degree is better to make a diy scanner because of easy cutting, it is just square!

about reflections you can solve that with a light in a taller spot . i mean if you enlarge the distance between the middle of the glasses and the light source.
so when you capture an image you can see a lighten cycle inside the space of the glass if you have not good degrees

: You mean reflection is light glare or page reflection? If it is light glare you are right. But if I use 90 degree, the distance from lamp to platen is shorter than 100 degree. Anyway, it is 100 degree is more better than 100 degree to take good pictures.

Thank you your concerns for my questions.

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

Post by dpc » 08 Aug 2017, 15:01

jck57 wrote:
04 Aug 2017, 12:04
Could you instead of raising the height of the light source, simply put a shade or baffle between the light source and the books so that light falls only on the pages?
The problem isn't that the light hits the the "outer" portion of the platen that isn't covering the actual page (you can zoom-in with the camera or clip the final photo to eliminate any reflections in that area). The problem is that the light can be seen by the camera in a reflection off of the platen glass over the actual page. The only ways to prevent this is to change the light position or change the angle of the platen. Since the platen angle needs to be something larger than 90 degrees (100 deg. is pretty good number for most designs) in order to prevent the reflection of light from the adjacent platen glass, moving the light source higher is the only viable solution.

The light source can be positioned lower if you're scanning books with narrower pages (i.e. paperbacks). Since most scanners are designed based on the anticipated largest book size (platen glass pane size, cradle transverse movement, etc.), the light source position is typically static and not adjustable.

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

Post by daniel_reetz » 13 Aug 2017, 09:59

dpc wrote:
10 Jul 2017, 15:22
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.
This is the effect that dpc is talking about:

Image

I don't know what's going on with those platen videos in the old thread. They're still on YouTube, I haven't changed anything. It's possible that the old embed code is broken. :/

Basically, as you've heard, the answer to the thread title ("Which one is better?") is that this is an engineering exercise, so what is better depends on what resources you have and what you're trying to do. DPC's trig method is the simplest way to get a theoretical answer, and I found it easiest to just move the light source vertically until it disappears (as you see in the gif).

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

Post by jck57 » 14 Aug 2017, 11:28

dpc wrote:
08 Aug 2017, 15:01
jck57 wrote:
04 Aug 2017, 12:04
Could you instead of raising the height of the light source, simply put a shade or baffle between the light source and the books so that light falls only on the pages?
The problem isn't that the light hits the the "outer" portion of the platen that isn't covering the actual page (you can zoom-in with the camera or clip the final photo to eliminate any reflections in that area). The problem is that the light can be seen by the camera in a reflection off of the platen glass over the actual page. The only ways to prevent this is to change the light position or change the angle of the platen. Since the platen angle needs to be something larger than 90 degrees (100 deg. is pretty good number for most designs) in order to prevent the reflection of light from the adjacent platen glass, moving the light source higher is the only viable solution.

The light source can be positioned lower if you're scanning books with narrower pages (i.e. paperbacks). Since most scanners are designed based on the anticipated largest book size (platen glass pane size, cradle transverse movement, etc.), the light source position is typically static and not adjustable.
Got it. Here's what I think is a solution to the 90 degree reflection problem without raising the light source. Let me know if I'm wrong. In the first pic we see a single light source which will not be picked up by the camera as long as angle B is greater than angle A. In the second pic two light sources are used closer to the platen with a baffle between them.
reflect1.jpg
reflect2.jpg

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

Post by dpc » 14 Aug 2017, 19:38

Got it. Here's what I think is a solution to the 90 degree reflection problem without raising the light source. Let me know if I'm wrong. In the first pic we see a single light source which will not be picked up by the camera as long as angle B is greater than angle A. In the second pic two light sources are used closer to the platen with a baffle between them.
I want to be sure we're talking about the same thing, so when you say "90 degree reflection problem" do you mean the problem of the reflection from the adjacent platen pane on to the platen pane current being shot by the camera? That problem isn't associated with the position of the light source at all. That is affected by the viewing angle from the camera, which can be changed by moving the camera position relative to the surface of the platen pane. A camera mounted far away will allow you to decrease the angle between the two platen planes, while moving it closer will require the angle to increase. Theoretically, a camera located at infinity could use a platen angle of 90 degrees, but for our purposes we typically use something closer to 100 degrees.

Since your diagrams include a light source that leads me to believe that you're talking about a way to eliminate the reflection of the light source off the platen glass pane and back into the camera. Unfortunately your baffles won't fix this problem. The reason is that the lights (and the baffle) are visble to the camera in the reflected view off the platen glass. Have a look at the following modified drawing that you posted:

Image

I've added shading to the areas of space defining the direct and reflected view space for each camera (these colored areas overlap so it looks a little busy but I hope you can follow it and understand what I'm attempting to say).

Looking at 'cam 1' on the left, the direct view space is defined by a cyan triangle, from the camera lens down to the platen surface (it changes color along the way due to intersection with the other areas). Anything that lies in this triangle will be directly visible in a photo taken by camera 1. Similarly, anything residing within the orange triangular region from 'cam 2' to the other platen surface will be visible in photos taken from camera 2.

Now reflected light can also hit the platen glass and be reflected back into the camera. Going back to 'cam 1', there is an area defined in blue of the region in space that this camera can see reflected off of the platen glass. Since we're talking about reflected light, the brighter the object is that lies in that blue region, the more prominent its reflection will be off of the glass. That's why you paint your scanner parts matte black and it's also why you don't want any light sources positioned in this area. The same thing goes for the red colored area that denotes the reflected view space for 'cam 2'.
As you can see, the only safe place to put a light source so that it won't contribute reflected light into the cameras is the area above the intersection of the blue and red regions in the drawing (tiny inverted white triangle near upper portion of the image).

It's worth noting that we're looking at a 2D drawing of these various viewing regions in what is actually a 3D view space. Reflected light in front and behind the scanner can also contribute to glare on your platen surface. This isn't typically an issue since most people turn off room lights and don't wear headlamps when scanning books so there isn't a problem with light coming in from these directions.

Hope that helps!
-d

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

Post by jck57 » 15 Aug 2017, 10:53

How about synchronizing and sequencing the lights and cameras? Camera 1 fires with only the RH light on. Camera 2 fires with only the LH light on.

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

Post by duerig » 15 Aug 2017, 12:26

jck57, it would be simple to control lights with a relay in the same way that we control cameras. I've already done something like this in a different context. But I'm not sure where the lights are in this example. The pictures show the lights as being directly above the platen. This would make them shine light evenly on each side. Are you envisioning a divider of some kind which is opaque between a pair of lighting modules at the top?

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