How to detect when a book is opened.

I am trying to determine the best way to go about monitoring the opened/closed status of a physical book.

The book is affixed to a platform and only the left side of the book can be opened/closed. The right side of the book is affixed.

Things I have considered:

*Hall sensor placed on the platform with magnet glued into the cover of the book so that when the book is opened, the front cover magnet touches the sensor. This is probably the best solution so far, but it doesn't really report when the book is "opened". It only report when the front cover is touching the platform and the book is completely opened.

*Photosensor placed in the same position so that the front cover blocks out light when it casts a shadow over the sensor. This would work, and trigger the "open" status quicker than the hall sensor, but there are other elements in my project that interfere with this sensor (its a long story).

*Hall sensor/magnet placed on the interior pages. Perhaps I could hollow out a few pages to hide these objects inside, but it would interfere with the reading of the book or make certain pages unreadable. The sensor needs to be as invisible as possible.

I think thats all I have thought of right now. Thanks in advance for all your brilliant ideas!

An accelerometer embedded inside the front cover. This would give the angle of the cover relative to its closed position. Wires to wherever the Arduino is hidden will need to be made of spring steel (like guitar strings) or tinsel wire to give the required fatigue resistance.

mikb55: An accelerometer embedded inside the front cover. This would give the angle of the cover relative to its closed position. Wires to wherever the Arduino is hidden will need to be made of spring steel (like guitar strings) or tinsel wire to give the required fatigue resistance.

Ahh this is a great idea! I might try embedding it in the spine of the book, as the spine changes angle almost as quickly as the front cover does when it opens. Thank you!

Flex sensor in the back of the book comes to mind.

Hi,

if the book cover is going to be fully open or fully closed then a couple of reed relays, as used in burglar alarm contacts, and a magnet in the cover should work.

Peter

book...book... I seem to remember that term.....

can you put a dust sensor nearby ? in the TV shows, they always show someone blowing off the dust.

the hall sensor can detect magnetic fields. a sufficiently powerful magnet placed under the book, may be able to be detected through the closed book

a light sensor on the book would see changes of light based on people standing over it, things placed on top, etc. a light sensor inside the front cover would be covered unless the book was opened. it would have to be located so papers of the closed book covered it, but not cover as the book opened.

I like the flex sensor and the acceleromater, both seem more independent from the pages of the book.

I think we need more of the details of the visibility of the device. and also the allowable size of it. Whatever you have, it will need power.

If this is an escape room prop, it is much easier than if it were a book in someone's library that should not easily be observed if it is any different than any other book.

Lastly, the spine opens with a gap. some sort of switch could be placed in that gap so the normal tension/pressure of the cover materials versus the no tension when opened. there are pressure sensitive mats like the membrane keys we use.

dave-in-nj:
Whatever you have, it will need power.

OP mentions the book being fixed in place; so bringing power to it (and a signal wire away from it) invisibly should be easy.

wvmarle:
OP mentions the book being fixed in place; so bringing power to it (and a signal wire away from it) invisibly should be easy.

it sounds like a prop for an escape room. that being the case, some destruction of the pages to allow for a magnet might be allowable. yes, he said he wanted to make it hard to know if the sensor exists…
A large magnet on the bottom and a Hall sensor on the top would be easy and readily available technology.
a tilt sensor, mercury in glass tube, could be inserted in the cover. they make them very tiny.

The age old resultant effecting of opening a book is added knowledge. :) :)

Maybe a weigh scale under the book area.

When the book is open, the open book will place some of its weight on the surface other than that where it is attached.

arduino_guidance_terminal: *Hall sensor placed on the platform with magnet glued into the cover of the book so that when the book is opened, the front cover magnet touches the sensor. This is probably the best solution so far, but it doesn't really report when the book is "opened". It only report when the front cover is touching the platform and the book is completely opened.

So put the Hall sensor under the book itself to detect the first act of lifting the cover. Given the magnet is strong - and thin!