Perusing patent filings is a great way to find out what your favorite mobile device company may be up to. For instance, one of the latest patent applications from RIM is interesting because it shows how the mob-e-mail and smartphone leader may attempt to improve the touch displays used in future BlackBerry models.

RIM, it appears, plans enhance its displays by merging the technology behind capacitive and resistive touch screens, both of which are used in today's smartphone, into a single new type of display that leverages the best of both worlds.

Capacitive displays are better for devices that rely on finger input, such as the iPhone. It detects a finger drawing off current from an electric field over the screen.

Whereas resistive, the cheaper technology, requires pressure to read input. Unlike capacitive, resistive technology works well with a stylus.

RIM's filing with the Patent Office is called ELECTRONIC DEVICE AND TOUCH SCREEN DISPLAY. The abract reads:

A touch screen display includes a display device, a resistive touch-sensitive overlay disposed on the display device and including a pair of touch-sensor layers separated by a gap, a resistive touch screen controller connected to each of the pair of touch-sensor layers for determining a position of a touch event on the touch-sensitive overlay and a capacitive controller connected to an outer one of the pair of touch-sensor layers for receiving input for determining changes resulting from capacitive coupling with the outer one of the pair of touch-sensor layers.

Combining capacitive and resistive screen types into a single hybrid display could get expensive, more so than either of them individually. So expect, if the display described in the filing becomes a reality, to initially only find it in high end smartphone. Perhaps in some future update to the BlackBerry Storm.