Apple patent is for mutual capacitance touch sensing device
Posted by Dennis Sellers 
Jan 10, 2008 at 11:01am
An Apple patent (number 20080006553) for a mutual capacitance touch sensing device has appeared at the U.S. Patent & Trademark Office. It relates generally to touch sensing devices used in portable electronic devices such as the iPhone and iPod touch. More particularly, the present invention relates to an improved mutual capacitance sensing touch device.
Here’s Apple’s summary of the invention: “The invention relates, in one embodiment, to a touch sensing device. The touch sensing device includes a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines, a source for driving a current or voltage separately though each drive line, a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines. The touch sensing device also includes a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array. Each node includes a drive electrode that is spatially separated from a sense electrode. The drive electrode is coupled to one of the drive lines and the sense electrode is coupled to one of the sense lines. Each node is set up with a different combination of drive and sense line coupled thereto.
“The invention relates, in another embodiment, to a touch sensing device that operates via mutual capacitance. The touch sensing device includes a mutual capacitance sensing node including a drive electrode that is spatially separated and juxtaposed next to a sense electrode. The drive electrode is coupled to a drive line and the sense electrode is coupled to a sense line of a mutual capacitance sensing circuit.
“The invention relates, in another embodiment, to a mutual capacitive sensing method. The method includes separately driving a voltage or current through each drive line. The method also includes capacitively coupling current between drive electrodes that are coupled to driven drive line and corresponding sense electrodes that are coupled to sense lines. The method further includes detecting capacitance at electrode pairs through each sense line each time a drive line is driven. The method additionally includes determining which electrode pairs have been touched based on detected capacitance. Moreover, the method includes performing actions based on which electrode pairs have been touched.”
A mutual capacitive touch sensing device is disclosed. The touch sensing device includes a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines; a source for driving a current or voltage separately though each drive line; and a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines. The touch sensing device also includes a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array. Each node includes a drive electrode that is spatially separated from a sense electrode. The drive electrode is coupled to one of the drive lines and the sense electrode is coupled to one of the sense lines. Each node is set up with a different combination of drive and sense line coupled thereto.
The inventor is Steve Hotelling. The graphic below is a circuit diagram of a mutual capacitive sensing input device, in accordance with one embodiment of the present invention.
The “Macsimum MWSF 2007 Coupon Book” is available for download. You can find it here and print it as a PDF. It has discounts, special offers and promotions in conjunction with the upcoming Macworld Conference & Expo in San Francisco.
Article Information
Comment on this Article Print this Article Email this Article Digg This
Contributor
Dennis Sellers
Dennis has been a newspaper editor/reporter (seven years) and teacher (seven years). He has over 4,000 magazine, newspaper and online articles to his credit. He has also covered the Mac and tech industries for over a decade for such online publications as MacCentral, MacMinute and now MacsimumNews.
