Typically monopolies lead to less efficient outcomes than competitive markets. How can a patent which grants a company the monopoly rights to a product result in an increase in welfare?

A patent refers to a right given to a firm by the government to solely produce a specified product or offer specific service over a certain period. Mostly, patents are given to individuals or companies who incentivize innovation. Through patents, a company enjoys a competitive advantage since it offers a unique product in the market, and market structure is monopolistic. Arguably, since the company enjoys monopoly power, it gains vast sales, which generates a lot of revenue. Thus upon earning revenues, the company increases its welfare.