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From the author of Types of Claims

Types of Claims

Claims can generally be categorized as apparatus claims, method claims, or combinations that are called the ever-dreaded “means-plus-function” claims. An apparatus claim describes a structure without describing what that structure does. An example apparatus claim is claim 1 from Asa Whitney’s US patent 1,653 for a locomotive engine (see Figure 1):

    1. The combination of the cog, or spur, wheel, with the two pair of driving wheels nearest to them, in combination with the rod connecting the front and rear wheels with the middle wheels, by which combination of the cog wheels and connecting rods with the driving wheels, the power the engine is communicated to the whole number of the driving wheels when the engine is put in motion.

Figure 1 Sample pages from Whitney's locomotive patent.

A method claim describes a function without describing the actual hardware or structure of the invention that performs the function. An example method claim is claim is claim 1 from Larry Page’s US patent 6,285,999 for a search engine (see Figure 2):

    1. A computer implemented method of scoring a plurality of linked documents, comprising:

    obtaining a plurality of documents, at least some of the documents being linked documents, at least some of the documents being linking documents, and at least some of the documents being both linked documents and linking documents, each of the linked documents being pointed to by a link in one or more of the linking documents;

    assigning a score to each of the linked documents based on scores of the one or more linking documents and

    processing the linked documents according to their scores.

Figure 2 A sample from Page's patent for a linked database

A means-plus-function claim describes an apparatus and also describes its function. It usually, but not always, contains the term “means for[el]” An example means-plus-function claim is claim 5 from Thomas Edison’s US patent 1,046,414 for a phonograph (see Figure 3):

    5. In a recording device for, recording sound waves, the combination with a body, of a diaphragm carried, thereby, a lever having at one end an adjustable connection with said body, said connection permitting, longitudinal adjustment of said lever, a support carried by said lever and adapted to engage the record, and means for adjusting the other end of said lever relative to said body, substantially as described.

Figure 3 Sample pages from Edison's phonograph patent

Means-plus-function claims are generally not good because in order to show that a device infringes on your patent, you must show that it has the structure described in the claim and that it also has the function described in the claim. It is better to divide the methods and the means into separate claims. Unfortunately, Thomas Edison didn’t have my advice; otherwise, he wouldn’t have written a means-plus-function claim and could have been a very successful inventor.

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