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Selective Touch Screen Disclosure Number: IPCOM000239230D
Original Publication Date: 2014-Oct-22
Included in the Prior Art Database: 2014-Oct-22
Document File: 4 page(s) / 595K

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Related People

Kovyazin, Rustam: INVENTOR


1) Capacitive and also projected capacitive touch screens detect user touch by change in capacitance. 2) Wearable signal generator is used. Electric signal fades while is passing through the user body. Different distances from the signal generators placement to the fingertips provide different path losses. Electric signal generator as the ring on the thumb or little finger is proposed but not limited. 3) If user touches the screen with fingertip then different level of signal inflicts different distortion on the touch screen surface. 4) Touch screen shall distinguish different levels of distortion, recognize coordinates, and which finger was used.

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Selective Touch Screen

By Rustam Kovyazin

Motorola Solutions, Inc.



Handheld devices are widely used. These devices are designed to use one or two finger usage and fingers are not distinguished. If different functions can be assigned to different fingers then it will significantly improve usability of handheld devices. This paper describes the method of distinguishing between fingertips which is based on WBAN approach.


Common handheld devices and tablets comprise a touch screen which is configured to be used by one or two fingers. One finger triggers the following gestures: taping, scrolling, dragging, etc. Two fingers trigger more complex gestures like zooming, rotating, etc. In both cases user interface (UI) does not distinguish fingers. If fingers are distinguished then new UI features, functionality, and user experience available for the devices with attached touch screen. Also new UI guidelines and recommendations may appear.

On the other hands desktop systems use pointing devices like mouse very intensively. Idea of desktop systems porting to the handheld devices is clear because user achieves the familiar UI. Right now desktop systems are hard to adapt to a handheld devices with attached touch screen. Common mouse contains at least two buttons: right and left. These buttons are assigned to the fingers’ gestures but substitution is not intuitive.

There is a need for a novel solution to the afore-mentioned problem.


The method of distinguishing between fingertips is based on Wireless Body Area Network (WBAN) application:

·         Electric signal generator is the wearable electronic device which is placed on the human (user) body.

·         Electric signal generator on-body placement makes signal run via different paths to the fingertips.

·         Electric signal fades while it passes though the human body. Different path to the fingertips inflicts different level of fading.

·         If user touches the surface of touch screen by the fingertip then different levels of the signal inflict different distortion of touch screen.

·         Touch screen detects different levels of distortion, recognizes coordinates, and which finger was used.


Proposed method can be applied to capacitive and capacitive projected touch screens. These types of touch screen form electrostatic field on the surface. If user performs the touch then it inflicts distortion of electrostatic field which can be measured as a change in capacitance.

Several methods of capacitance measurement exist. The following method is described in [1]:

·         Grid of electrodes is charged / discharged periodically and charging / discharging time (hereinafter referred as CD-time) is measured.

·         If user’s finger is nearby then electrode’s capacitance is charged and discharged much slower.

·         Thereby CD-time changes and identifies finger touch.

·         Electrode index identifies coordinates of the touch.

Modern touch screens detect only binary set of conditions: touch and no touch (refer to...