The Patently Apple site reported that the US Patent and Trademark Office has officially described another core iPhone multitouch patent, increasing the iPhone makers portfolio of patents. As per this report, the new multitouch related patent is based on the oscillator signal and circuit. It is key to sensing a touch event on a touch display, wrote Patently Apple.

According to Patently Apple, the growing arsenal of Apple patents will help the company in legal disputes against those vendors trying to copy iPhone and iPad designs. “It's one of the 200 patents that late Steve Jobs pointed to when launching the iPhone,” wrote Patently Apple.

As per the description, conventional touch panel technologies are limited to single point or touch event. But, in reality, multiple objects come into contact with the sensing surface. Hence, they lack the ability to track multiple points of contact at the same time. Also, many touch-panel devices use oscillating signals to power and clock electronic elements.

While there are several known methods of generating an oscillating signal, most of them do not provide a signal with precision and frequency predictability. Apple's granted patent corrects this problem. Apple said that they incorporate the content of several other major multitouch patents into this patent. Apple said, “In general, multi-touch panels may be able to detect multiple touches (touch events or contact points) that occur at or about the same time, and identify and track their locations.”

The Patently Apple report highlights a few major claims made by the company. It includes a method for tuning a local oscillator of an event-sensitive device, an event sensor device comprising a local oscillator circuit configured to generate an oscillating signal having a frequency at least partially based on an incoming control signal, and a calibration controller configured to modify a frequency of the oscillating signal by controlling the oscillating circuit.

Apple credits Thomas Wilson as the sole inventor of this patent which was originally filed in January 2007.