On May 16, 2013, the US Patent & Trademark Office published a patent application from Apple that reveals an all-new touch sensor panel design for larger displays. Today's touch sensor panels are designed like a checkerboard taking on a matrix of drive and sense lines arranged in rows and columns in horizontal and vertical directions. That may be fine for smaller touch displays but as the touch displays become larger such as those for a future MacBook or even an iMac, the current design becomes a drag on the speed of touch command execution. Apple's next generation touch sensor panel is likely to take on either a web-like design or one that incorporates thick diamond-like shapes so that the user's finger is more likely to hit the sensors faster and easier.
Apple's Patent Background
Part of Apple's patent background states that touch sensing pixels can be varied in size and/or spacing to enable touch sensitivity in large panels without increasing the number of drive and sense lines which can otherwise increase the processing burden and can cause negative optical artifacts when viewing the display device through the touch panel. However, increasing the size and/or spacing of the touch sensing pixels can negatively impact the resistance and capacitance (RC) time constant per pixel, thereby hindering touch sensitivity of the touch panel and limiting the speed at which the touch panel can operate.
Apple's Proposes a New Touch Sensor Panel Design
Technically speaking, Apple's invention relates to a touch sensor panel including a plurality of shaped drive lines and a plurality of shaped sense lines formed on the same layer and utilizing conductive jumpers in crossover locations, according to one example. The plurality of drive lines and the plurality of sense lines can be formed by interconnecting sections of at least one conductive material having a truncated diamond shape to reduce parasitic capacitance, although other shapes can also be used. Either the sections of the plurality of drive lines or the sections of the plurality of sense lines can be interconnected with one or more conductive cross-overs, which can be an opaque metal or other conductive material. A black mask or other opaque covering can be layered over the one or more conductive cross-overs to minimize visual artifacts. Also, at least one conductive dummy region can be disposed in an area of the touch sensor panel around the truncated diamond shaped sections of the plurality of drive lines and the plurality of sense lines to improve optical uniformity and enhance the touch detection capabilities of the touch sensor panel. One or more metal lines can be formed overlapping and electrically connected to the interconnected sections of each of the plurality of drive lines and the plurality of sense lines in order to further reduce resistance.
In an alternate example, the plurality of drive lines and the plurality of sense lines can be formed by interconnecting sections of interconnected conductive lines. According to an example, the interconnected conductive lines are formed of sections of at least one conductive material having an interdigitated comb design. The sections can be formed from a substantially transparent conductive material such as ITO, for example. Alternatively, the interconnected conductive lines may be thin metal lines in a web-like formation, without the substantially transparent conductive material.
Apple Invents All-New Touch Sensor Panel Design
In April we posted a report titled "Finally, Apple reveals their Hybrid Notebook Tablet Details." The report, amongst other things, discussed the Notebook-Tablet hybrid device's touch display and its unique technique of using magnets to remove and reattach the display to the keyboard.
Today, the US Patent Office revealed a new patent application from Apple that's all about an all-new touch sensor panel design. You should take note that Apple's patent application was only filed four months ago and it's not associated with any other patent such as provisional patent, nor is it a continuation of another older patent. This is why this is a patent to take careful notice of.
Admittedly, it's an overly technical patent that only those in the field of touch displays could truly appreciate. Apple provides us with very little to grasp onto here for their reasoning for this new sensor panel design except for one tiny admission. The new design is to accommodate larger displays for a computer system which they spell out at the very end of the patent as relating to a notebook, a future MacBook (Air or Pro). Although the technology could also apply to a future iPhone and iPod touch, Apple's all-important "Patent Claims" give the "computer system" priority in sequence, which isn't accidental.
Additionally, in the very first paragraph delving into the details of their invention they clearly state that "This relates to the formation of touch sensor panels, and in some examples, larger-size touch sensor panels." That's very specific.
Later in the patent to further clarify that the technology applies to a "computer system" Apple states that a "Computing system can also include host processor for receiving outputs from processor subsystems and performing actions based on the outputs that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device."
And lastly, Apple ends their patent application with mention of patent FIG. 13(c) which states the following: FIG. 13(c) illustrates an example personal computer that can include touch sensor panel (trackpad) and display, the touch sensor panel and/or display of the personal computer (in examples where the display is part of a touch screen) including a touch pixel design according to the various examples described herein."
Considering that this is a patent application and not a design patent, Apple only has to convey the idea and not the design. This is a 2013 patent, so obviously the design illustrated below isn't about an old MacBook. It's just a standard conceptual graphic. The point is that the larger display of Apple's patent claims is in fact a notebook.
At the end of the day, we've seen two recent Apple inventions that support the design of touch displays designed specifically for a notebook-tablet hybrid. To accommodate such a design, Apple has had to rethink the touch sensor panel design and that's a great indication that this is a serious research and development project on the move.
Apple credits Seung Hong, Martin Grunthaner, Steven Hotelling and Lynn Youngs as the inventors of this patent application which was filed in January 2013 and published today by the US Patent and Trademark Office.
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