# How the QR Code Works > The 1995 patent by Toyota Central R&D Labs that invented the QR code, using three distinct corner squares with a unique 1:1:3:1:1 pixel ratio to let scanners instantly find and read the code from any angle. - **Patent:** US 5726435 - **Original title:** Optically readable two-dimensional code and method and apparatus using the same - **Owner:** Toyota Central R&D Labs Inc - **Granted:** 1998 - **Status:** Public domain (expired) - **Times cited:** 250 - **Field:** consumer_electronics, software, automotive, ecommerce ## What it does The patent describes a square two-dimensional barcode containing data cells and three specific positioning symbols at its corners. These positioning symbols consist of concentric black and white squares. When a scanner draws a line through the center of any of these symbols at any angle, it always detects a specific pattern of dark and light widths in a 1:1:3:1:1 ratio. The scanner uses this unique ratio to locate the boundaries and rotational angle of the code. It then uses alternating light and dark timing cells to align its reading grid and decode the data stored in the remaining cells. ## What it does NOT cover - Does not cover standard one-dimensional barcodes that only store data along a single horizontal axis. - Does not cover two-dimensional codes that use circular or hexagonal grid layouts instead of a square matrix. - Does not cover codes that rely on color variations rather than binary dark and light cells to store data. - Does not cover codes that lack the specific 1:1:3:1:1 ratio positioning symbols at three corners. ## The clever bit The inventors realized that a 1:1:3:1:1 ratio of dark and light areas rarely occurs in printed text or packaging. By placing three squares with this exact ratio in the corners, a scanner can instantly find the code's orientation in a fraction of a second, regardless of rotation. ## Real-world examples 1. QR codes on restaurant tables for digital menus 2. Boarding passes and concert tickets scanned at gates 3. Mobile payment codes in apps like WeChat Pay and Venmo 4. Inventory tracking labels on automotive parts ## Why it matters This patent laid the foundation for the QR (Quick Response) code, which replaced traditional barcodes in manufacturing and logistics because it could hold vastly more data and be scanned from any angle. Originally designed to track automotive parts in Toyota factories, it became a global standard for mobile payments, digital ticketing, and contactless menus. ## Frequently asked questions ### What does How the QR Code Works cover? The 1995 patent by Toyota Central R&D Labs that invented the QR code, using three distinct corner squares with a unique 1:1:3:1:1 pixel ratio to let scanners instantly find and read the code from any angle. ### Who owns patent US 5726435? Toyota Central R&D Labs Inc owns this patent, granted in 1998. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 5726435 cited by? This patent has been cited by 250 later patents that build on its ideas. ### What problem does this patent solve? This patent laid the foundation for the QR (Quick Response) code, which replaced traditional barcodes in manufacturing and logistics because it could hold vastly more data and be scanned from any angle. Originally designed to track automotive parts in Toyota factories, it became a global standard for mobile payments, digital ticketing, and contactless menus. ### What does this patent NOT cover? Does not cover standard one-dimensional barcodes that only store data along a single horizontal axis. **Full plain-English explainer:** https://patentbrief.org/patent/us/5726435/qr-code-two-dimensional-barcode **Original patent:** https://patents.google.com/patent/US5726435 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Mobile Phones Can Securely Authorize Payments Using Random ID Codes](https://patentbrief.org/patent/us/7577616/method-and-apparatus-of-secure-authentication-and-electronic-payment-through-mobile-communication-tool) — A 2006 system that uses a mobile phone to receive and relay a unique, temporary ID code to a store terminal to verify and authorize a payment transaction. - [How Mobile Devices Use Tags to Close Restaurant Checks](https://patentbrief.org/patent/us/10559047/systems-and-methods-for-facilitating-closing-of-a-check) — A system for restaurant servers to open and close customer tabs by tapping a mobile device against a physical tag at a table. - [How Laser Printers Use Rotating Mirrors to Write Information](https://patentbrief.org/patent/us/3867571/laser-printer-starkweather) — A 1972 Xerox patent describing how to use a spinning mirror to scan a laser beam across a page, adjusting the speed of the data to keep the image sharp. - [How Douglas Engelbart Invented the Computer Mouse](https://patentbrief.org/patent/us/3541541/computer-mouse-input-device) — The 1970 patent for the X-Y position indicator, better known as the computer mouse, which allowed users to move a cursor across a screen for the first time. - [How Touchscreens Understand Your Finger Swipes and Scrolls](https://patentbrief.org/patent/us/7479949/iphone-multi-touch) — This patent describes how touchscreens use smart rules, called heuristics, to figure out if your finger movement means scrolling up, moving around a map, or flipping to the next photo, especially by looking at how you start your swipe.