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.

What it covers

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 doesn't 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.

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.

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