How Computers Learn to Track Your Eyes Better
This patent describes a method for eye-tracking systems to get more accurate by first asking you to look at specific points, and then secretly improving its accuracy as you use the computer normally.
Original patent title: “Gaze calibration”
This patent describes a method for eye-tracking systems to get more accurate by first asking you to look at specific points, and then secretly improving its accuracy as you use the computer normally. Granted to Microsoft Technology Licensing in 2017 with 18 claims and 2 forward citations, and it is expected to expire in 2034.
Coverage
What does this patent actually cover?
The patent describes a way for computers to precisely track a user's eye movements, called gaze tracking. It uses a two-step process. First, an "explicit calibration phase" (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1) shows several "calibration markers" (like dots) on the screen. The user clicks or taps these markers, and the system records both where the user clicked and where their eyes were looking at that exact moment. This initial data helps the system learn how the user's eye movements relate to screen positions. Second, an "implicit calibration phase" (Claim 1) continuously refines this accuracy without interrupting the user. While the user interacts with the computer, like clicking on a button, the system checks if the actual click location is close to where the user's eyes were looking. If it is, this data helps "recalibrate the stream of gaze measurements" (Claim 1) and is stored in a "recalibration buffer" (Claim 1). If the click is far from the gaze, it might indicate an error, populating an "error buffer" (Claim 4) which can trigger a new explicit calibration (Claim 5). For example, if you're playing a game using eye-tracking, the system might initially ask you to click a few targets, then silently improve its tracking as you click on game elements.
The gap
What does this patent NOT cover?
- Does not cover gaze tracking systems that only use an initial setup without any continuous, background recalibration.
- Does not cover calibration methods that rely solely on passive observation of eye movements without requiring manual user input events (like clicks or touches).
- Does not cover systems where the implicit recalibration phase disturbs the user's ongoing interaction with the computing device.
- Does not cover calibration where the system cannot associate a manual user input event with a specific location on the display.
- Does not cover systems that only use an "error buffer" to trigger recalibration without also having a "recalibration buffer" for continuous refinement.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → lies in combining an initial, focused calibration with a continuous, "stealthy" recalibration that leverages normal user interactions. By using manual input events (like clicks) during regular use, the system can subtly correct its understanding of where the user is looking, making the eye-tracker more accurate and less intrusive over time.
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
Tobii eye trackers for PC gaming
Eye-tracking features in Microsoft Windows (e.g., Eye Control)
Accessibility tools for users with motor impairments
Virtual reality headsets with integrated eye tracking
Research systems for user experience studies
Why it matters
The bigger picture
Accurate gaze tracking is crucial for accessibility, gaming, and interacting with augmented or virtual reality. This patent helps make eye-tracking technology more practical by improving its reliability over time without constantly bothering the user. Better calibration means smoother, more natural control for users who rely on eye movements, or for applications where precise gaze input is critical.
Filed
April 30, 2014
Granted
August 8, 2017
Market context
Who's building on this
Companies in this space
Microsoft, the assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, continues to develop accessibility features and integrate eye-tracking into its operating systems and devices. Companies like Tobii AB are leaders in eye-tracking hardware and software, often incorporating sophisticated calibration techniques. Other firms developing VR/AR headsets, such as Meta and Apple, are also investing in integrated eye-tracking solutions that require robust calibration.
Market impact
This patent contributed to the development of more reliable and user-friendly gaze-tracking systems. By enabling continuous, non-disruptive recalibration, it helped make eye-tracking a more viable input method for a wider range of applications, from assistive technologies to immersive gaming, reducing the frustration of frequent manual recalibrations and improving overall user experience.
Claim 1 — Plain English
What this patent covers
The patent describes a way for computers to precisely track a user's eye movements, called gaze tracking. It uses a two-step process. First, an "explicit calibration phase" (Claim 1) shows several "calibration markers" (like dots) on the screen. The user clicks or taps these markers, and the system records both where the user clicked and where their eyes were looking at that exact moment. This initial data helps the system learn how the user's eye movements relate to screen positions. Second, an "implicit calibration phase" (Claim 1) continuously refines this accuracy without interrupting the user. While the user interacts with the computer, like clicking on a button, the system checks if the actual click location is close to where the user's eyes were looking. If it is, this data helps "recalibrate the stream of gaze measurements" (Claim 1) and is stored in a "recalibration buffer" (Claim 1). If the click is far from the gaze, it might indicate an error, populating an "error buffer" (Claim 4) which can trigger a new explicit calibration (Claim 5). For example, if you're playing a game using eye-tracking, the system might initially ask you to click a few targets, then silently improve its tracking as you click on game elements.
The clever bit
The novelty lies in combining an initial, focused calibration with a continuous, "stealthy" recalibration that leverages normal user interactions. By using manual input events (like clicks) during regular use, the system can subtly correct its understanding of where the user is looking, making the eye-tracker more accurate and less intrusive over time.
What it does not cover
- Does not cover gaze tracking systems that only use an initial setup without any continuous, background recalibration.
- Does not cover calibration methods that rely solely on passive observation of eye movements without requiring manual user input events (like clicks or touches).
- Does not cover systems where the implicit recalibration phase disturbs the user's ongoing interaction with the computing device.
- Does not cover calibration where the system cannot associate a manual user input event with a specific location on the display.
- Does not cover systems that only use an "error buffer" to trigger recalibration without also having a "recalibration buffer" for continuous refinement.
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
Moderate
Citation count
10/40
Early citations
Claim breadth
12/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
10/20
Granted 5–10 years ago
Assignee scale
20/20
Major company or institution
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
$62K – $200K
Midpoint $125K · 7.7 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
18 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Sellen, A. J., Woodberry, K. R., Ciptadi, A., Emfield, A. G., & Blake, A. (2017). How Computers Learn to Track Your Eyes Better (U.S. Patent No. 9,727,135). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/9727135/gaze-calibration
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 Computers Learn to Track Your Eyes Better cover?
This patent describes a method for eye-tracking systems to get more accurate by first asking you to look at specific points, and then secretly improving its accuracy as you use the computer normally.
Who owns patent US 9727135?
Microsoft Technology Licensing owns this patent, granted in 2017.
When does this patent expire?
This patent is expected to expire on April 30, 2034, when the invention enters the public domain.
What is patent US 9727135 cited by?
This patent has been cited by 2 later patents that build on its ideas.
What problem does this patent solve?
Accurate gaze tracking is crucial for accessibility, gaming, and interacting with augmented or virtual reality. This patent helps make eye-tracking technology more practical by improving its reliability over time without constantly bothering the user. Better calibration means smoother, more natural control for users who rely on eye movements, or for applications where precise gaze input is critical.
What does this patent NOT cover?
Does not cover gaze tracking systems that only use an initial setup without any continuous, background recalibration.
Same assignee
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