It is impossible to search provisional patents online because provisional patents are never published (see Advantages and Disadvantages page). Furthermore, viewing a provisional patent would not give you much information because it has not yet gone through the entire patent process and you would not know what the final claims are. Therefore, it would be a lot smarter (and easier) to search for issued patents and pending patents that are related to your invention instead of trying to search for provisional patents.
Remember, you can only get a patent on an invention that is new and not obvious. So you should really spend some time making sure that nobody else has created the same thing as you before you waste your time and money on filing a patent application. The easiest way to do this is to spend an hour or two searching google.com and google.com/patents. Try to think of different keywords to describe your idea and search using those keywords. Using google.com/patents, print out or bookmark patents that are closely related to yours. You can then use those patents later as templates to help write your patent application. If you find something that is exactly the same, than you should not try to file a patent because the patent office will tell you that your idea is not new. However, most likely you will find one or two differences between your idea and what is already described in another patent and the patent application that you write should focus on those differences. Most new patent application are actually on slight improvements to old inventions and this is okay.
Videos on how to search provisional patents:
download powerpoint here: how-to-patent-search
download pdf of slides here: how-to-patent-search (1)
Next Up: When to File a Provisional Patent
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