How does the 'Automatically Sleep and Wake' toggle switch work?

[Dr. Drib]

This is a serious question.

I'm one of the few who purchased a new and bad (?) Kobo Origami cover for my new Kobo Libra 2.

When folded back, almost any slight alignment/movement of the case causes the ereader to turn off. So, I simply disabled the sleep/wake function by turning off the firmware toggle switch on my Reader.

This works fine - and I can live with it - but I was wondering how this toggle switch actually works to neutralize the sleep/wake function of the Reader.

By the way, I love how the Reader simply 'slips' into the cover. It's so easy to disengage the Reader from the case. Sometimes I use the case and sometimes I don't. But...the toggle switch now stays off.

[NiLuJe]

What the software sees when the hall sensor is tripped is essentially a key press (on contact, e.g., cover closed) and a key lift (on lift, e.g., cover opened), so it's as "simple" as ignoring those.

(Note the quotes, because said events might actually wake the device up if alseep regardless of what userland does with it, so it requires further trickery to avoid false wakeups, but a sane implementation should be transparent to the user on that front... when it works (c.f., the varied history of battery issues with wonky covers )).

Note that some/all (never had one with a cover myself) Kindles went the extra mile to cover (ha!) more of those potential cover issues by having *multiple* hall sensors, some calibrated for the front of the device, and some calibrated for the back.

[JSWolf]

I have a Kobo origami cover and I cannot get it to put my Libra 2 to sleep when it's fully folded back. It works perfectly.

My You could try some aluminum foil to block the magnets on the back.

[Dr. Drib]

I heard that aluminum foil does not actually block magnets.

Do you have any additional info on aluminum foil?

And do you know where is the magnet on the cover placed?

[Quoth]

Originally Posted by Dr. Drib

I heard that aluminum foil does not actually block magnets.

It doesn't, but of course the extra gap due to the foil will reduce the magnetic field.

[NiLuJe]

The position of the sensor (and by extension, of the cover's magnet(s)) is highly device-specific (it's often near a corner, or at least close to/behind the bezel: it's rarely stranded in the middle of the device ). I have a fridge magnet on hand that I use to test this ;p.

[Dr. Drib]

Originally Posted by NiLuJe

The position of the sensor (and by extension, of the cover's magnet(s)) is highly device-specific (it's often near of corner, or at least close to/behind the bezel: it's rarely stranded in the middle of the device ). I have a fridge magnet on hand that I use to test this ;p.

I hadn't thought of that. I'll try it and see where the magnet is located.

[NiLuJe]

You'll want a clunky one with an actual strong enough magnet, not a sticker-like flat one .

(Or... basically, a magnet? Actual magnets used for pinning stuff down on black/white boards might do the job too).

[fogice]

The magnet is here on the Libra 2. I successfully used aluminum foil folded to be 8 layers thick behind this spot.

I'm also curious to know how the sensor works.

[Dr. Drib]

Originally Posted by fogice

The magnet is here on the Libra 2. I successfully used aluminum foil folded to be 8 layers thick behind this spot.

I'm also curious to know how the sensor works.

I discovered where the magnet was, and your post further verifies that.

I used aluminum foil, but it didn't work. Based upon your solution, I'll try again and use more.

Thank you.

[Dr. Drib]

Increasing the thickness of the aluminum foil did the trick.

[JSWolf]

Originally Posted by fogice

The magnet is here on the Libra 2. I successfully used aluminum foil folded to be 8 layers thick behind this spot.

I'm also curious to know how the sensor works.

That's not a picture of a Libra 2. Would you mind showing us on a Libra 2 instead of a Libra H2O?

[Quoth]

Originally Posted by fogice

The magnet is here on the Libra 2. I successfully used aluminum foil folded to be 8 layers thick behind this spot.

I'm also curious to know how the sensor works.

It's not a magnet. It's a transistor like device that's sensitive to a magnetic field. It's called the Hall effect, so they are sold as Hall Effect Sensors. They are about half the size of a match head.

A piece of card or plastic will work as well as aluminium foil, as it's just the spacing.

Before the Hall Effect Sensor was perfected as a commercial device the simplest magnet operated switch was the reed switch. The smallest ones are slightly bigger diameter glass tube than a match stick, and about half the length, with the two metal reeds inside that contact if a strong enough magnet is close enough. Still used as sensors on doors and windows for burglar alarms till recently.

Some ereaders do have magnets inside to act as a catch for a cover. This is a stupid idea (loads in a Sage) because the magnets may cancel the sleep cover magnet of a second eink, phone or tablet when stacked on a table or in a bag. These are stronger magnets than the small one in a cover to operate the Hall Sensor device in the eReader, phone or tablet.

Gory technical details that are mostly correct. I have a bunch of the sensors in a drawer that look like little plastic cased transistors for "projects". A reed switch is bulky and fragile. The Hall Effect sensor can give a variable output so can bed used even for a contactless throttle on an electric scooter or machine as well as to compare magnets.
https://en.wikipedia.org/wiki/Hall_effect

[fogice]

Originally Posted by JSWolf

That's not a picture of a Libra 2. Would you mind showing us on a Libra 2 instead of a Libra H2O?

Ah, shoot. I did an image search for Libra 2, and that's the one I grabbed. I drew the star on it myself, so I know that is the correct location for the on/off sensor.

[fogice]

Originally Posted by Quoth

The Hall Effect sensor can give a variable output so can bed used even for a contactless throttle on an electric scooter or machine as well as to compare magnets.

Cool! So it is possible that the threshold value that they use for on/off might just be set too low. I wonder if that's a user-accessible value somewhere in the config files.