How to read a patent

A number such as EP 4822876 A1 has three parts. The two letters say which office published it: EP is the European Patent Office, US the United States, CN China, JP Japan, KR South Korea, DE Germany, and WO the World Intellectual Property Organization for international applications.

The digits are that office's own serial number. They are only unique together with the office letters: US 4822876 and EP 4822876 are unrelated documents.

The letter and digit at the end are the kind code. It says what was published: usually A for an application and B for a granted patent. The same invention is published several times as it moves through an office, so EP 4822876 A1 and a later EP 4822876 B1 are two stages of one European patent.

An invention patent (a "utility patent" in the US) protects how something works. It is examined before grant and lasts at most 20 years from the filing date, if renewal fees are paid.

A utility model is a quicker, cheaper right offered by countries such as China (kind U), Germany (U1), Japan and Korea. It is registered without full examination and usually lasts 10 years.

A design patent or design registration protects how something looks, not how it works (US kind S, about 15 years from grant).

An international (PCT) application, published with WO, is not a patent. It is one filing that keeps the door open in more than 150 countries; protection only comes from the national or regional patents that follow it, usually within 30 or 31 months of the first filing.

Software is not a separate type: inventions implemented in software are ordinary invention patents, accepted when they solve a technical problem. US provisional applications are never published, so they appear only as the priority date of later patents.

Priority date: the first filing anywhere for this invention. Later filings in other countries within 12 months can claim it, so it is the date that counts when deciding what was new.

Filing date: when this particular application was filed. The 20-year maximum term runs from here.

Publication date: applications are usually published about 18 months after the priority date, whether or not they will ever be granted. That is why most new documents are applications (kind A).

Grant date: when the office decided to grant. Many applications are never granted, or are granted with narrower claims than they were filed with.

End: at most 20 years from filing, earlier if renewal fees stop or the patent is revoked. Medicines and plant-protection products can get up to five more years through a supplementary protection certificate. Dates on YouGotIdeas are estimates from the published record.

Companies file the same invention in several countries. All the documents that share the same priority filings form a patent family: for example a Japanese application, its US and Chinese counterparts, a European patent and a PCT application.

The EPO keeps two kinds of family: the simple family, with exactly the same priorities, and the wider INPADOC family, linked by any shared priority. YouGotIdeas uses the family to show where an invention is protected and to fetch its legal events only once per family.

Every patent is sorted into the Cooperative Patent Classification (CPC), shared by the European and US offices and used by many others. A code such as H01M 10/613 reads from broad to narrow.

H is the section (Electricity). H01 is the class (basic electric elements). H01M is the subclass (batteries and fuel cells), which is what YouGotIdeas calls an industry. 10 is the main group (secondary batteries, the rechargeable kind) and /613 the subgroup (cooling them).

The nine sections are A human necessities, B operations and transport, C chemistry and metallurgy, D textiles and paper, E fixed constructions, F mechanical engineering, lighting, heating and weapons, G physics, H electricity, and Y technologies that span sections, such as climate-change mitigation. A patent usually carries several codes, which is how one invention can sit in more than one industry.

The applicant is who filed: usually a company, sometimes a university or a person. Inventors are the people who made the invention, and they are always named, even when their employer owns the patent.

Ownership can change after filing through sales and mergers, and the published record does not always follow. YouGotIdeas shows the applicant as filed and merges spellings of the same company (for example Toyota written in English and in Chinese), labelling those merges as derived.

The title and abstract describe the invention briefly; they do not set what is protected. The claims do: numbered sentences at the end of the document that define exactly what others may not do. The description and drawings explain the claims, and the reference numbers in the drawings (10, 12, 14…) point at the parts named in the text.

YouGotIdeas shows the title, the abstract and the first drawing, and writes a plain-English reading from the title and abstract. That reading is labelled as AI, is checked against the abstract, and is never a legal interpretation of the claims.

Examiners list earlier documents that matter for novelty, with a letter: X means relevant on its own, Y relevant in combination with another document, and A general background. Many X citations suggest the claims may be narrowed before any grant.

Citations also show how ideas build on each other: YouGotIdeas uses them, together with shared classification codes and companies, to link industries.

A patent only protects in the countries where it was granted and is kept alive. The legal-status events published by each office (grant, lapse for non-payment, withdrawal, revocation) show where it stands.

YouGotIdeas reads those events from the EPO's INPADOC database and estimates a status and an end date. Event wording differs by country, so treat the status as a well-founded estimate and check the office register before relying on it.