Generally, a patent application for the invention which has been either published or publicly displayed cannot be filed. However the Patents Act provides a grace period of 12 months for filing of patent application from the date of its publication in a journal or its public display in a exhibition organised by the Government or disclosure before any learned society or published by applicant. The details conditions are provided under Chapter VI of the Act (Section 29-34).
A Patent is a statutory right for an invention granted for a limited period of time to the patentee by the Government, in exchange of full disclosure of his invention for excluding others, from making, using, selling, importing the patented product or process for producing that product for those purposes without his consent.
Patent protection is territorial right and therefore it is effective only within the territory of India. However, filing an application in India enables the applicant to file a corresponding application for same invention in convention countries, within or before expiry of twelve months from the filing date in India. Therefore, separate patents should be obtained in each country where the applicant requires protection of his invention in those countries. There is no patent valid worldwide.