How Smartphones Use Light Sensors to Detect When You Are Talking
Apple's patent on using light sensors to help a phone accurately detect when it is pressed against your ear, preventing accidental screen touches.
Original patent title: “Using ambient light sensor to augment proximity sensor output”
Apple's patent on using light sensors to help a phone accurately detect when it is pressed against your ear, preventing accidental screen touches. Granted to Apple Inc in 2013 with 27 claims and 59 forward citations.
Key facts
Coverage
What does this patent actually cover?
This patent describes a method for improving the reliability of a phone's proximity sensor. Proximity sensors often struggle in low-light conditions, potentially failing to lock the screen when you hold the phone to your face. The system uses data from an ambient light sensor (ALS) to adjust the proximity reading dynamically. If the light level is very low, the system assumes the phone is likely covered by an object like a cheek or ear and adjusts the proximity threshold accordingly to ensure the screen turns off.
The gap
What does this patent NOT cover?
- Does not cover proximity sensing that relies exclusively on infrared or ultrasonic hardware without light sensor input.
- Does not cover methods that adjust screen brightness based on ambient light without also altering the proximity determination.
- Does not cover touch-based proximity detection that does not involve an earpiece-adjacent sensor configuration.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
It treats the ambient light sensor not just as a tool for screen brightness, but as a secondary data source to 'vet' the accuracy of the proximity sensor, effectively using two different types of hardware to solve a single signal-noise problem.
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
iPhone proximity sensor behavior during phone calls
Modern smartphone screen-off logic during calls
Why it matters
The bigger picture
This technology is essential for the modern smartphone user experience. Without it, phones would frequently wake the screen while on a call, leading to accidental inputs like muting the call or hanging up with your ear. It helped solidify the reliability of the iPhone during the transition to all-touch interfaces.
Filed
April 28, 2011
Granted
December 3, 2013
Market context
Who's building on this
Companies in this space
Apple continues to refine this sensor fusion approach in modern iPhones. Other major smartphone manufacturers like Samsung and Google also utilize similar multi-sensor inputs to manage screen states during calls, as sensor fusion is now a standard practice in mobile hardware engineering.
Market impact
This patent helped standardize the expectation that a smartphone screen should reliably turn off during a call. It provided a robust technical solution to a common usability frustration, effectively setting a baseline for hardware-software integration in the mobile industry.
Claim 1 — Plain English
What this patent covers
This patent describes a method for improving the reliability of a phone's proximity sensor. Proximity sensors often struggle in low-light conditions, potentially failing to lock the screen when you hold the phone to your face. The system uses data from an ambient light sensor (ALS) to adjust the proximity reading dynamically. If the light level is very low, the system assumes the phone is likely covered by an object like a cheek or ear and adjusts the proximity threshold accordingly to ensure the screen turns off.
The clever bit
It treats the ambient light sensor not just as a tool for screen brightness, but as a secondary data source to 'vet' the accuracy of the proximity sensor, effectively using two different types of hardware to solve a single signal-noise problem.
What it does not cover
- Does not cover proximity sensing that relies exclusively on infrared or ultrasonic hardware without light sensor input.
- Does not cover methods that adjust screen brightness based on ambient light without also altering the proximity determination.
- Does not cover touch-based proximity detection that does not involve an earpiece-adjacent sensor configuration.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Strong
Citation count
35/40
Highly cited
Claim breadth
18/20
Very broad protection
Recency
5/20
Granted 10–20 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
$328K – $1.0M
Midpoint $655K · 4.9 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.
The original legal language
Original claims
27 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Westerman, W. C., Hotelling, S. P., Yepez, R. G., & Herz, S. M. (2013). How Smartphones Use Light Sensors to Detect When You Are Talking (U.S. Patent No. 8,600,430). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/8600430/imessage
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US8600430"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4965188 · 1990
How to Make Many Copies of a DNA Piece with Heat
This patent describes the Polymerase Chain Reaction (PCR) method, a technique to make millions of copies of a specific DNA segment using a heat-resistant enzyme and repeated temperature changes.
Cetus Corp
US 4235871 · 1980
How to Encapsulate Active Materials in Lipid Bubbles Efficiently
This patent describes a method for trapping biologically active substances inside tiny, multi-layered fat bubbles called liposomes, using a specific water-in-oil emulsion and gel-forming process to improve how much material gets captured.
Individual
More to explore
More in Consumer Electronics
US 7657849 · 2010 · Apple Inc
How the iPhone's Slide-to-Unlock Gesture Works
US 7479949 · 2009 · Apple Inc
How Touchscreens Understand Your Finger Swipes and Scrolls
US 4528643 · 1985 · FPDC Inc
How Stores Make Custom Products On-Demand with Remote Approval
US 7469381 · 2008 · Apple Inc
How Touchscreens Show and Snap Back When You Scroll Past an Edge
New to patents?
Common Questions
Frequently Asked Questions
What does How Smartphones Use Light Sensors to Detect When You Are Talking cover?
Apple's patent on using light sensors to help a phone accurately detect when it is pressed against your ear, preventing accidental screen touches.
Who owns patent US 8600430?
Apple Inc owns this patent, granted in 2013.
When does this patent expire?
This patent is expected to expire on December 3, 2033, when the invention enters the public domain.
What is patent US 8600430 cited by?
This patent has been cited by 59 later patents that build on its ideas.
What problem does this patent solve?
This technology is essential for the modern smartphone user experience. Without it, phones would frequently wake the screen while on a call, leading to accidental inputs like muting the call or hanging up with your ear. It helped solidify the reliability of the iPhone during the transition to all-touch interfaces.
What does this patent NOT cover?
Does not cover proximity sensing that relies exclusively on infrared or ultrasonic hardware without light sensor input.
Same assignee
More from Apple Inc
Patent monitoring