# How Keurig's Original Single-Serve Coffee Pod System Works > This 1994 patent describes the original Keurig system for brewing single cups of coffee using a special filter pod that holds coffee grounds and separates them from the brewed liquid. - **Patent:** US 5325765 - **Original title:** Beverage filter cartridge - **Owner:** Keurig Inc - **Granted:** 1994 - **Status:** Public domain (expired) - **Times cited:** 359 - **Field:** consumer_electronics, food_and_beverage, mechanical ## What it does This patent details a system for brewing beverages, specifically coffee, using a special cartridge. The cartridge has a base and a cover, both impermeable and pierceable. Inside, a filter element divides the cartridge into two chambers: one for beverage extract (like coffee grounds) and another for the brewed liquid. When you use the machine, liquid is injected into the first chamber to combine with the extract. The filter then lets the brewed beverage pass into the second chamber, from where it flows out. Claims 1 and 2 describe the core components: a housing with a brewing chamber, a pierceable cartridge inside, and means to inject liquid and collect the beverage. For example, Claim 15 specifies how the liquid inlet might go through one part of the housing and the outlet through another. ## What it does NOT cover - Beverage cartridges that are not internally divided by a filter element. - Systems where the filter element does not create two separate chambers within the cartridge. - Cartridges that are not pierceable by inlet and outlet means. - Brewing systems that do not use a removable cartridge. - Methods of brewing that do not involve combining liquid with a beverage extract stored in a chamber. ## The clever bit The key innovation was creating a self-contained, pierceable cartridge where the filter element itself acts as a divider, precisely separating the grounds from the brewed liquid and ensuring a clean, consistent brew without complex internal machine mechanisms for filtration. ## Real-world examples 1. Original Keurig K-Cup brewing machines 2. Early Keurig coffee pods ## Why it matters This patent is foundational to the single-serve coffee revolution. It describes the core technology behind the Keurig brewing system, which transformed how people make coffee at home and in offices by offering convenience and variety in a single-cup format. ## Frequently asked questions ### What does How Keurig's Original Single-Serve Coffee Pod System Works cover? This 1994 patent describes the original Keurig system for brewing single cups of coffee using a special filter pod that holds coffee grounds and separates them from the brewed liquid. ### Who owns patent US 5325765? Keurig Inc owns this patent, granted in 1994. ### 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 5325765 cited by? This patent has been cited by 359 later patents that build on its ideas. ### What problem does this patent solve? This patent is foundational to the single-serve coffee revolution. It describes the core technology behind the Keurig brewing system, which transformed how people make coffee at home and in offices by offering convenience and variety in a single-cup format. ### What does this patent NOT cover? Beverage cartridges that are not internally divided by a filter element. **Full plain-English explainer:** https://patentbrief.org/patent/us/5325765/keurig-single-serve-coffee-pod **Original patent:** https://patents.google.com/patent/US5325765 --- _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 a Coffee Maker Uses a Floating Valve to Heat Water](https://patentbrief.org/patent/us/3693535/mr-coffee-drip-coffee-maker) — A 1971 invention for a coffee maker that uses a floating valve to control water flow, ensuring water is heated efficiently without needing a massive, power-hungry heating element. - [How the Modern Disposable Paper Cup Was Invented](https://patentbrief.org/patent/us/1032557/dixie-cup-disposable-paper-cup) — A 1908 patent for a sanitary, single-use paper cup designed to prevent the spread of germs from shared public drinking vessels. - [How Polaroid's Instant Film Pods Work](https://patentbrief.org/patent/us/2543181/polaroid-instant-camera) — A 1951 invention by Edwin Land that enabled instant photography by packaging liquid developer inside a breakable pod attached to the film sheet. - [How the Modern Paper Drinking Straw Was Invented](https://patentbrief.org/patent/us/375962/drinking-straw-stone) — A 19th-century patent for a paper tube coated in wax, designed to replace natural rye grass straws for drinking beverages. - [How the Modern Waterbed Works](https://patentbrief.org/patent/us/3585356/waterbed-liquid-support) — A 1971 patent describing a liquid-filled, heated furniture support designed to cradle human bodies without letting them touch the bottom of the container.