A team from Microsoft Research in China, which developed the new system, said wireless charging pads are more convenient than traditional wired smartphone chargers, but they still require users to consciously place their phone in a specific spot.
The new AutoCharge system allows users to put their phone down anywhere on a regular table to be recharged.
Using an overhead camera and object recognition software, AutoCharge continuously scans the table top, looking for smartphone-shaped objects.
It can detect one in less than a second and then it shines a beam of focused light onto it. Both the camera and the light can rotate, in order to image and illuminate the target from an optimum angle, 'Gizmag' reported.
A photovoltaic (PV) panel on that phone subsequently generates electricity from that light, charging the phone's battery.
The researchers said that in tests of the prototype using a phone-sized PV panel, it was found to charge phones approximately as fast as some wired chargers.
In order to keep from continuously lighting up phones that don't need charging, AutoCharge utilises a system in which the PV panel powers a microcontroller and an LED indicator on the top surface of the phone.
When the phone is first illuminated, that LED blinks in a specific pattern, indicating the battery's current charge level. AutoCharge uses its camera to detect that pattern, and only keeps illuminating the phone if it needs to get charged.
Once the phone's battery is full, the LED will flash in a different pattern, letting AutoCharge know that it's time to stop.