Patents are used to help researchers make a profit from their work. The Wikipedia explains.
Free Patents Online
Is recommended as a source of free information. You can search by subject or by the originating research outfit. Sadly the Patent Office Library has been taken into the British Library, the ugly brick building near Saint Pancras but you can get access after an interview.
NTIS - National Technical Information Service
The NTIS is an American government source. It is splendid apart from one aspect. They charge money to get anything. This is a pity.
A patent (pronounced /ˈpætənt/ or /ˈpeɪtənt/) is a set of exclusive rights granted by a state (national government) to an inventor or their assignee for a limited period of time in exchange for a public disclosure of an invention.
The procedure for granting patents, the requirements placed on the patentee, and the extent of the exclusive rights vary widely between countries according to national laws and international agreements. Typically, however, a patent application must include one or more claims defining the invention which must be new, non-obvious, and useful or industrially applicable. In many countries, certain subject areas are excluded from patents, such as business methods and mental acts. The exclusive right granted to a patentee in most countries is the right to prevent others from making, using, selling, or distributing the patented invention without permission. It is just a right to prevent others' use. A patent does not give the proprietor of the patent the right to use the patented invention, should it fall within the scope of an earlier patent.
Under the World Trade Organization's (WTO) Agreement on Trade-Related Aspects of Intellectual Property Rights, patents should be available in WTO member states for any inventions, in all fields of technology, and the term of protection available should be the minimum twenty years. Different types of patents may have varying patent terms (i.e., durations).
There are international aspects to intellectual property law. Enforcing rights in foreign jurisdictions can be difficult.
The Patents Act 1977 (as amended)
1. Patentable inventions
3. Inventive step
4. Industrial application
4A. Methods of treatment or diagnosis
5. Priority date
6. Disclosure of matter, etc., between earlier and later application
Right to apply for and obtain a patent and be mentioned as inventor
7. Right to apply for and obtain a patent
8. Determination before grant of questions about entitlement to patents, etc.
9. Determination after grant of questions referred to before grant
10. Handling of application by joint applicants
11. Effect of transfer of application under section 8 or 10
12. Determination of questions about entitlement to foreign and convention patents, etc.
13. Mention of inventor
These are just some of the sections. They will not bother with perpetual motion machines, quite rightly.