Compared with other portable devices, smart watches need low energy consumption and can change the color of the display screen. But with ambient light sensor in the narrow fuselage is very difficult. Apple may have by April this year to apply for the patent to solve this problem. The application is designed by Apple's human perception of environmental light. "Apple mentioned environmental sensor the traditional light sensing technology rely on embedded at the bottom of the screen. The apple iPhone and iPad are in the bottom of the screen with the ambient light sensor module.

Compared with the mobile phone and tablet computer, smart watches.Apple Watch internal space less like Apple Watch has been equipped with a loudspeaker and optical detection equipment, including a large heart rate sensor and induction charging device. Apple mentioned in the patent, can increase the ambient light sensor in the Apple below Watch, this design can increase the function without affecting the appearance the case.

Apple said that the body or the skin can become ambient light and optical sensor interface. Through the skin of the ambient light can be reflected back to the optical sensor, and converted into a measurable current or voltage. In some cases, the sensor can detect different light and environmental light, the collected data can be used to adjust the equipment the screen, more accurately restore the screen color, also is the basis of True Tone display. Currently, Apple has been equipped with True Tone display in the 9.7 inch iPad Pro.