Apple Invents an Advanced Stylus Touch Controller Architecture
On February 05, 2015, the U.S. Patent & Trademark Office published a pair of patent applications from Apple that reveals their second and third stylus patent applications for 2015 after applying for ten original patents in 2014. Last week we posted a report titled "Apple Invents a Superheterodyne Pen Stimulus Receiver to Overcome the Classic Stylus Latency Problem." Today Apple's patent application covers a new stylus touch controller architecture that recognizes both touch and stylus events. The depth of these patent applications from Apple clearly shows us just how sophisticated their future smart pen will be in contrast to the old dumb stylus of yesteryear.
Apple Invents a Stylus Touch Controller Architecture
In general, the touch sensitive device can recognize a touch or a hover event and the position of the event on the touch panel, and the computing system can then interpret the event in accordance with the display appearing at the time of the event, and thereafter can perform one or more actions based on the event.
Touch sensitive devices are being developed to recognize more and more types of touch and hover-events. Apple recognized that device circuitry needed to be developed to perform an increasing number of events in a timely and accurate manner.
Apple's invention generally relates to a stylus and, more specifically, to a stylus that can be used with a touch controller architecture that can be configured according to a scan plan.
More specifically, Apple's invention relates to a touch controller that can configure touch circuitry according to a scan plan, which can define a sequence of scan events to be performed on a touch panel. The touch controller can include a configurable transmit section to generate stimulation signals to drive the panel, a configurable receive section to receive and process touch signals from the panel, and a configurable memory to store the touch signals.
The touch controller can also include a programmable scan engine to configure the transmit section, the receive section, and the memory according to the scan plan.
The touch controller can advantageously provide more robust and flexible touch circuitry to handle various types of touch events at the panel. This also relates to an active stylus that can generate stimulation signals that can be detected by the touch controller during scan events at the panel.
Apple's patent FIG. 1 noted below illustrates an exemplary computing system implementing an exemplary touch controller that can detect both touch and hover events caused by objects such as a finger or a stylus.
A Stylus Spectral Scan
In Apple's patent FIG. 16 noted below we're able to see an exemplary method for handling a stylus spectral scan event. Here, the scan engine can receive a stylus spectral analysis scan event from a scan plan (#1605). The scan engine can then determine a stylus connection or reconnection status (1610).
If the stylus is not connected or reconnected, the scan engine can configure the touch circuitry to perform the stylus spectral analysis scan to determine one or more clean frequencies for the stylus (#1630) when the stylus is not transmitting.
If the stylus is connected or reconnected, the scan engine can then determine whether the stylus is synchronous or asynchronous (#1615). If the stylus is synchronous, the scan engine can configure the touch circuitry to perform a stylus spectral analysis scan. If the stylus is asynchronous, the scan engine can determine if the stylus is detected on the panel (#1620). If the stylus is detected on the panel, the scan engine can skip the stylus spectral analysis scan (#1625).
If the stylus is not detected on the panel, the scan engine can configure the touch circuitry to perform a stylus spectral analysis scan after which the computing system can communicate one or more clean stylus frequencies to the stylus and update the one or more stylus frequencies for detection in the touch controller (#1635).
Scan Architecture for a Touch Controller Configuring a Master-Slave Circuit
Apple's patent FIG. 18 noted above is an exemplary scan architecture for a touch controller configuring a master-slave circuit, which can include touch circuitry for a master touch circuit and touch circuitry for a slave touch circuit. .
In some examples, the master-slave circuit can be a single package containing two touch controllers, while in other examples the master-slave circuit can include two separate touch controller chips.
In the example of FIG. 18, the scan engine can configure both the master and slave touch circuitry to execute a scan plan together. For example, the master and slave touch circuitry can drive and sense different row and column traces such that the combination scans all of the rows and columns of the touch sensor panel.
As illustrated in FIG. 18, during the first scan event, both the master and slave circuitry can be configured to perform mutual capacitance column-column scans on the respective row and column traces. Similarly, the remaining scan events can be performed by the master and slave circuitry. When the panel scan engine generates an interrupt command, the slave circuit can transfer its scan event results to the master circuit, which can then send the results to the RAM for storage.
In some examples, the master and slave touch controllers can provide for a bi-directional data transfer to enable both controllers to have the full image of touch. Master-slave configurations can allow for scanning high density touch sensor panels (e.g. a 40.times.30 array of rows and columns) with low density circuits (master and slave circuits can each stimulate 20 rows and sense touch signals generated by any of the 40 rows on 15 columns).
Apple credits Shahrooz Shahparnia as the sole inventor patent applications 20150035769 and 20150035797 which were originally filed in Q3 2014. Considering that this is a patent application, the timing of such a product to market is unknown at this time. To review other Apple Smart Pen patent filings, see our archives.
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