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Writing a patent application (page 4 of 8)

From: Canadian Intellectual Property Office


The description in your patent application starts off with general background information and moves on to more detailed information about your invention and its parts. By starting with an overview and continuing with more detail, you bring the reader along in a full description of your invention.

You must write a complete and full description because you cannot add any new information to your patent application once you have filed it. You can only make changes to the subject matter that the original drawings or description suggest. Be careful not to add any false information or leave out important items. If you hire a registered patent agent, they can help you get as much protection as possible for your invention.

Although drawings are not part of the description, you should refer to them to explain your invention. Include chemical and mathematical formulas in the description wherever it makes sense.

Some examples

Here is an example of a description for a collapsible tent frame. The applicant begins by giving background information and talking about similar patents. The section then continues with a summary of the invention. Following this is a list of the figures and a detailed description of each part of the invention.

The description of this patent for an electrical connector is divided into: background of the invention, a summary of the invention, a short description of the drawings and a detailed description of the invention.

Below are some "how to" instructions to help get you started. When you are happy with the description, you can begin the claims section. Remember that the description and claims are the main part of your application. Once you have polished these sections, most of your work is done!

How to write the description

When you are writing the description, try to follow this format:

You might find it helpful to jot down brief notes about the points you want to cover under the above headings. You may also wish to use this outline as a guide:

  1. Begin on a new page by stating the title of your invention. Make it short, precise and specific. For example, if your invention is a compound, say "Carbon tetrachoride" not "Compound". Avoid naming the invention after you or using the words “new” or “improved”. Aim to give your application a title that people can find using a few key words during a patent search.
  2. Write a general statement that explains the technical field related to your invention.
  3. Continue by writing background information that will help people who want to understand, search or examine your invention.
  4. Discuss the problems that inventors have faced in this area and how they have worked to solve those problems. This is often called giving prior art. Prior art is the published knowledge that relates to your invention. At this point in the process, applicants often quote previous similar patents.
  5. Write in general terms how your invention solves one or several of the problems that inventors have faced. What you are trying to show is how your invention is new and different.
  6. List the drawings giving the figure number and a brief description of what the drawings show. Remember to refer to drawings all through your detailed description, and use the same reference numbers for each part of the drawings.
  7. Describe your invention in detail. For a device or product, describe each part, how they fit together and how they work together. For a process, describe each step, what you start with, what you need to do to make the change, and the end result. For a compound, include the chemical formula, the structure, and the process that could be used to make the compound. You need to make the description fit all the possible alternatives that relate to your invention. If a part can be made out of several different materials, say so. You should aim to describe each part in enough detail so that someone could make at least one version of your invention.
  8. Give an example of how your invention could be used.

Note: You should also include any warnings not already commonly used in the field that would be necessary to prevent your invention from failing.

If it is relevant, give the biological sequence listing of your compound. The sequence is part of the description so you should not include it with any drawings.

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