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Ah, I misread your question. According to their notes, "Rather than a single touchscreen controller, Apple went with a multi-chip solution to handle the larger

by m_eiman 14y ago

Ah, I misread your question. According to their notes, "Rather than a single touchscreen controller, Apple went with a multi-chip solution to handle the larger screen size, à la iPad.". But I'd guess that it's not (just) the size that makes them use two chips; since they're different chips they probably have different strenghts and weaknesses. Or maybe just having two different representations of each touch make it possible to be more accurate.

pja 14y ago
Maybe one for multitouch and one for more accurate single touch detection?
- esolyt 14y ago
  There can't be separate touch controller for "multitouch". In fact the word multitouch is not even a technical term. Touchscreens are multitouch by default. The two chips probably work in parallel to handle the needs of the larger touchscreen. Galaxy Tab 10.1 actually has three Atmel touch controllers, which is probably why scrolling on it is smoother than most Android devices.
  - pja 14y ago
    Enlighten me: How exactly does having two, or even three controllers make for smoother scrolling? Assume I know nothing about touch screen controllers!
    - Someone 14y ago
      Speculation (I know nothing about the technology, either): There are two factors to smooth scrolling: - high-resolution, low latency measurement of finger location. - fast, low latency scrolling of screen content. I guess one can use multiple detectors to increase spatial resolution of position detection. For example, with two detectors that each have a X DPI resolution, one could place them in two layers, staggered from each other behind the screen to double resolution in one direction. Alternatively, if there is no technical limitation to DPI, it might be a limitation to the controllers one can buy. If they have a maximum number of lines they can detect, one could use two controllers, each one covering half the screen, and double resolution that way.

by m_eiman 14y ago

pja 14y ago

Maybe one for multitouch and one for more accurate single touch detection?

esolyt 14y ago
There can't be separate touch controller for "multitouch". In fact the word multitouch is not even a technical term. Touchscreens are multitouch by default. The two chips probably work in parallel to handle the needs of the larger touchscreen. Galaxy Tab 10.1 actually has three Atmel touch controllers, which is probably why scrolling on it is smoother than most Android devices.
- pja 14y ago
  Enlighten me: How exactly does having two, or even three controllers make for smoother scrolling? Assume I know nothing about touch screen controllers!
  - Someone 14y ago
    Speculation (I know nothing about the technology, either): There are two factors to smooth scrolling: - high-resolution, low latency measurement of finger location. - fast, low latency scrolling of screen content. I guess one can use multiple detectors to increase spatial resolution of position detection. For example, with two detectors that each have a X DPI resolution, one could place them in two layers, staggered from each other behind the screen to double resolution in one direction. Alternatively, if there is no technical limitation to DPI, it might be a limitation to the controllers one can buy. If they have a maximum number of lines they can detect, one could use two controllers, each one covering half the screen, and double resolution that way.