Why Apple’s 16-Inch Macbook Pro Knows What Angle You Open Your Lid


Apple 16 inch MacBook Pro Battery 111319 Credit: Apple

In an internal document for Apple Authorized Service Providers obtained by MacRumors, there’s a reference to a new “lid angle sensor” that seems to not only track the opening and closing of the MacBook’s lid, but the precise position that it’s opened to.

Although iFixit did a full teardown of the new 16-inch MacBook Pro earlier this week, it seems to have missed this new sensor the first time around, however after MacRumors pointed it out, iFixit took another look and discovered it nestled into the left-side hinge area of the MacBook Pro, with a magnet embedded in the hinge itself.

MacBook Lid Angle Sensor

Of course, a lid sensor by itself isn’t particularly new or surprising — Apple’s MacBooks have had them for years to detect when the lid is closed so that the MacBook can go to sleep, and to allow it to wake up when it’s reopened.

However, by all reports this sensor is considerably more sophisticated than anything Apple has done before, since it can actually determine exactly what position the lid is in, and possibly even how often it’s adjusted.

Why Would Your MacBook Pro Need This?

The service provider document seems to simply mention the sensor, but doesn’t appear to offer any explanation for exactly why it’s there, so there are few clues as to why Apple thinks it needs this.

iFixit takes the slightly cynical view that Apple may be using it to track how often the MacBook Pro’s lid is opened, closed, or adjusted for those situations like ‘Flexgate’ where the display or frayed flex cables need to be repaired. This could simply be for Apple’s own edification, but it’s also conceivably possible it could use this information to deny repairs in scenarios where it deems the lid to have been abused, such as being opened to extreme angles. It certainly wouldn’t be the first time that Apple would rather pretend a problem doesn’t exist.

No evidence has yet been found that Apple is actually logging any information from this sensor, however, so it could just as easily be something that Apple has put in place for a future macOS feature. While it’s hard to imagine a specific user-facing application for, it could be used for a future Face ID setup to help determine the camera angle, or even to control display illumination.

It could also simply be part of the advanced thermal management system on the new MacBook Pro, designed to adjust the fan speed and other cooling factors based on the angle of the lid, since airflow around a partially closed lid would be different than it would be when the lid is fully open.

Apple’s service document mentions the sensor primarily to explain to technicians how to calibrate it in the event of a display repair or replacement, but doesn’t offer any other information about why it’s there or what it could be used for.

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