How Touchscreens Tell Real Touches From False Ghost Touches
A method for capacitive touchscreens to distinguish between actual finger presses and false ghost signals that occur when multiple points are touched simultaneously.
Original patent title: “Ghost resolution for a capacitive touch panel”
A method for capacitive touchscreens to distinguish between actual finger presses and false ghost signals that occur when multiple points are touched simultaneously. Granted to Elan Microelectronics Corp in 2013 with 19 claims and 2 forward citations, and it is expected to expire in 2029.
Coverage
What does this patent actually cover?
When you touch a capacitive screen in two places, the grid of wires can sometimes create two extra 'ghost' points, making the device think you touched four spots. This patent describes a method to resolve this by charging the intersecting wires at each suspected point and measuring the resulting capacitance. By comparing the summed-up electrical values of these points, the system can mathematically determine which points are physically being touched and which are merely electrical artifacts. It then removes the false ghost points from the system's active list.
The gap
What does this patent NOT cover?
- Does not cover touchscreens that use resistive technology rather than capacitive sensing.
- Does not cover software-level gesture recognition or palm rejection algorithms.
- Does not cover hardware designs that physically prevent ghosting through shielding or specialized grid layouts.
- Does not cover methods that rely solely on time-domain analysis without concurrent charging of traces.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
Instead of just looking at raw signal strength, the method uses a comparative summation of capacitance values across intersecting traces to mathematically isolate the 'real' signal from the 'ghost' signal.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Early multi-touch capacitive smartphone screens
Capacitive tablet digitizers
Industrial touch-control panels
Why it matters
The bigger picture
Multi-touch screens rely on a grid of sensors. When users touch multiple points, the grid can report ambiguous data. This patent provided a specific mathematical approach for manufacturers like Elan Microelectronics to improve accuracy in early multi-touch devices, reducing the frustration of 'phantom' inputs that plagued early smartphone and tablet screens.
Filed
December 30, 2009
Granted
December 31, 2013
Market context
Who's building on this
Companies in this space
Elan Microelectronics remains a major player in the touch controller IC market. Their work in ghost resolution is standard practice for companies designing capacitive touch controllers, including competitors like Synaptics and Cypress Semiconductor, who utilize similar signal processing techniques to maintain touch accuracy.
Market impact
This technology helped stabilize the user experience for multi-touch devices during the rapid expansion of the smartphone market between 2010 and 2015. By providing a reliable way to filter noise, it enabled more complex multi-finger gestures to be implemented without the risk of erratic input behavior.
Claim 1 — Plain English
What this patent covers
When you touch a capacitive screen in two places, the grid of wires can sometimes create two extra 'ghost' points, making the device think you touched four spots. This patent describes a method to resolve this by charging the intersecting wires at each suspected point and measuring the resulting capacitance. By comparing the summed-up electrical values of these points, the system can mathematically determine which points are physically being touched and which are merely electrical artifacts. It then removes the false ghost points from the system's active list.
The clever bit
Instead of just looking at raw signal strength, the method uses a comparative summation of capacitance values across intersecting traces to mathematically isolate the 'real' signal from the 'ghost' signal.
What it does not cover
- Does not cover touchscreens that use resistive technology rather than capacitive sensing.
- Does not cover software-level gesture recognition or palm rejection algorithms.
- Does not cover hardware designs that physically prevent ghosting through shielding or specialized grid layouts.
- Does not cover methods that rely solely on time-domain analysis without concurrent charging of traces.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Early stage
Citation count
10/40
Early citations
Claim breadth
13/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$55K – $175K
Midpoint $109K · 3.5 yr remaining · industry ×1.6
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
19 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Lin, M., Kuo, P., Tao, Y., Tsai, H., & Lin, C. (2013). How Touchscreens Tell Real Touches From False Ghost Touches (U.S. Patent No. 8,619,056). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/8619056/ghost-resolution-for-a-capacitive-touch-panel
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Touchscreens Tell Real Touches From False Ghost Touches cover?
A method for capacitive touchscreens to distinguish between actual finger presses and false ghost signals that occur when multiple points are touched simultaneously.
Who owns patent US 8619056?
Elan Microelectronics Corp owns this patent, granted in 2013.
When does this patent expire?
This patent is expected to expire on December 30, 2029, when the invention enters the public domain.
What is patent US 8619056 cited by?
This patent has been cited by 2 later patents that build on its ideas.
What problem does this patent solve?
Multi-touch screens rely on a grid of sensors. When users touch multiple points, the grid can report ambiguous data. This patent provided a specific mathematical approach for manufacturers like Elan Microelectronics to improve accuracy in early multi-touch devices, reducing the frustration of 'phantom' inputs that plagued early smartphone and tablet screens.
What does this patent NOT cover?
Does not cover touchscreens that use resistive technology rather than capacitive sensing.
Patent monitoring