A booklight invisible to everyone but you

One of the problems about sleeping in the same room as your toddlers is that you can't use standard booklights for the fear of waking them up.
This is also true (for me) when reading on the airplane.

Off-the-shelf booklights are really bright from all around.

This is why I decided to create this booklight that is (near) invisible from everyone else but you.

From the reader, it's looks as bright as any other booklight,

but from an offset angle, it's hard to tell if it's even on or not.


As you can see, the further you move away from the front of the book (where the reader probably is), the light appears darker.
Because of this, you can read books in the dark without worrying about annoying those around you.

Make one for yourself

I also have a quick introductory video on how it works:

(1) Create the frame

I made a frame by hand-sawing wood, but it can really be anything. 3D print it if you like.
You have to make sure you make the measurements considering the size of the book.
Also attach some LEDs on the side.
These tape LEDs I used are pretty convenient.

 

(2) Apply privacy filter

This is the most important step: go buy a privacy screen filter for tablets (like these) and apply it over your frame.

Privacy screen filters work to allow light travelling perpendicularly to the film through, but cuts light travelling at an angle.

By applying this over the LED, it lets only light that is travelling towards the reader, and makes it invisible to those around you, which is exactly what we want.

You may need to do some painting to ensure that light doesn't leak from gaps and cracks between the filter and the frame.

(3) The "page turning" switch
At the moment, there is a serious flaw with usability which is that, whenever you lift the booklight from the page you're reading (to turn the page), light leaks from beneath.
This means that for every page turn, people around you are treated to a flash of LED light.
This is why I added a tact switch to the bottom of the booklight which presses ON only when the booklight is placed on a book.
This means that the light turns itself off automatically when you're page turning, which is great!
Take a look at the video above to see how this works.


Attach a battery pack, and you're done.


An option you could do is add an off-tact switch to the top of the booklight too, so that if you place the booklight between pages, you can use it as a bookmarker (and it'll turn off automatically when you do.)
Another thing I've thought about is putting a sensor (e.g accelerometer) to measure your page turning, and detect when you've fallen asleep, to turn off automatically.

I've personally found this to be really useful, and it's allowed me to get back into the habit of reading books before going to sleep.
I'd love to hear feedback/suggestions, and hope others will try making one of their own.

Ken 16/02/24