Today, the U.S. Patent and Trademark Office published two patent applications from Apple that reveal details behind their new Apple Pencil. The first filing is titled "Stylus Tilt and Orientation Estimation from Touch Sensor Panel Images." The second Apple Pencil invention is titled "Reduce Stylus Tip Wobble when Coupled to Capacitive Sensor."
In the first Apple Pencil patent application Apple notes that as touch sensing technology continues to improve, touch sensitive devices are increasingly being used to compose and mark-up electronic documents. In particular, styli have become popular input devices as they emulate the feel of traditional writing instruments. When a stylus interacts with a touch sensitive device, information about the stylus' orientation relative to the touch sensitive device (i.e., the tilt of the stylus) can allow the touch sensitive device to more accurately map the stylus' location on the touch sensor panel by minimizing the parallax error between the stylus tip and the touch nodes of the touch sensor panel.
Apple's first Apple Pencil related invention relates to detection of an orientation of a stylus relative to a touch sensitive surface. In one example, a touch image of the stylus tip and the hand used to grasp the stylus can be captured by the touch sensor panel and analyzed to determine the stylus' orientation relative to the surface of the touch sensor panel. The analysis can include estimating the size of the user's hand, determining the distance away from the user's hand at which the stylus tip makes contact with the touch sensor panel, and determining an angle of tilt based on the estimated size of the user's hand and the distance between the tip and the user's hand.
Apple's patent FIG. 6 illustrates an exemplary touch on a touch sensor panel by a user's hand and stylus; FIGS. 7a and 7b illustrate exemplary touch images of portions of a user's hand and stylus; FIG. 8a illustrates an exemplary method for determining a tilt of the stylus relative to a touch sensor panel.
Apple tells us in the marketing literature that "Two tilt sensors built within the tip of Apple Pencil calculate the exact orientation and angle of your hand. As you naturally write or draw, the relative positions of each of these sensors can be detected by the Multi-Touch display. So you can create shading effects simply by tilting Apple Pencil the way you would a charcoal or conventional pencil."
Apple's patent FIG. 8b illustrates an exemplary method for determining a tilt of the stylus relative to a touch sensor panel.
In the example of FIG. 8b, the user's hand can appear on a touch image to be composed of an ellipse (representing the side of the hand) with a plurality of knuckles represented by circles. You could read more about FIG. 8b in Apple's patent filing under patent point #0037.
Apple patent application 20150331508 was originally filed in Q2 2014. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
The second Apple Pencil patent application published today is titled "Reduce Stylus Tip Wobble when Coupled to Capacitive Sensor." This second stylus invention relates to an algorithm for reducing stylus tip wobble for a stylus translating on a surface over and between electrodes of a touch sensor panel. You could read more about this invention here.
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