Thursday, July 17, 2008

Apple's iPhone multi-touch patents - updated July, 2008

Last week, several iPhone and multi-touch patents are published through USPTO.

User Interface

FIG. 9 illustrates a screen display of an interactive gesture learning application in the form of a game according to some embodiments of the present invention.

Although multi-touch increases input freedom, users have to remember many gestures to fully use their multi-touch devices. This patent application presents methods to make people naturally familiar with multi-touch gestures. One example is shown below, where a user learns multi-touch gestures by games such as Tetris, Final Fantasy, etc.



Improvement of usability by removing accidental activation

A plot of empirically determined data illustrating patch minor radii's ability to discriminate between palm contacts and other touch-surface contacts (e.g., fingertips and thumbs).

These patent applications details methods to identify objects on or above a touch screen. Such information is very useful to prevent accidental activation due to inadvertent contact.



A perspective view of an exemplary sensor panel with rows and columns on opposite sides of substrate according to one embodiment of this invention.

In these patents, you can find how Apple engineers mechanically configure the touch panel and other sensors into iPhone.


Sensor calibration

Like other sensors, capacitive touch sensors also suffer from various noises. To enhance the performance of the sensor system, it is crucial to calibrate sensors correctly. US 2008/0158176 and US 2008/0162996 present methods to calibrate sensors automatically.


New multi-touch screens and pads

An exemplary circuit capable of measuring pulse travel times to allow for equalization of the spatial dependency of the pulse travel times according to one embodiment of this invention.

In the patent application US2008/0158198, the author tries to build a single-layered multi-touch screen while iPhone utilizes a two-layered touch panel. Its sensing mechnism is unique. Let me quote the author's summary.

A multi-touch sensor panel can be constructed on a single surface of a touch substrate to reduce manufacturing costs and minimize light loss in transparent embodiments. The panel can be formed as a plurality of distributed RC lines arranged in an array of rows and columns. Each distributed RC line can include alternating connected transistors and metal pads formed on a single surface of a sensor panel substrate, with the drain and source terminals of the transistors connected to adjacent metal pads.

The proposed device is a single-layered capacitive touch screen and cannot capture two dimensional touch images. That is, it also suffers from ghost-touch phenomenon like other conventional touch screens. Although the patent application details disambiguation process, I don't think that it is a true multi-touch screen.

Ghost Touch

However, once the rows and columns containing finger contacts are known, the un-equalized left-to-right, right-to-left, top-to-bottom and bottom-to-top pulse travel time data can be used to determine the relative positions of the fingers within the rows and columns and un-ambiguously determine the positions of all the finger contacts. In particular, for each row indicating a possible contact, the pulse travel times for right-to-left and left-to-right are compared against other rows for which there were possible contacts, one by one, to establish the relative positions of the contacts across the rows. After all rows have been processed, the same process is then repeated for each column showing a possible contact. For each column indicating a possible contact, the pulse travel times for top-to-bottom and bottom-to-top are compared against other columns for which there were possible contacts, one by one, to establish the relative positions of the contacts across the columns.


In this patent, two types of sensors - IR sensors and capacitive touch sensors - are combined together to result in a new proximity detecting touch screens/pads. Following is a quotation from the patent application:

Future touch panels can detect multiple touches and near touches (within the near-field detection capabilities of their touch sensors) occurring at about the same time, and identify and track their locations.

In addition, the authors details various configuration of the hybrid touch sensors:

One or more proximity sensors can be used in conjunction with a multi-touch panel. In some embodiments, an exemplary multi-touch panel can include a proximity sensor located at every touch sensor or pixel. In other embodiments, a proximity sensor can be selectively deployed at certain pixels where the detection of touch or hover may be more critical, or in a spread pattern in broad hover-sensitive areas. In still other embodiments, some rows in the multi-touch panel could be proximity sensor rows, with others being touch sensor rows.


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