In a previous article, we set out four tips for inventors, start-ups, and small businesses to consider before filing for a patent: (1) don’t wait to file your patent application; (2) decide where your invention will be practiced or marketed; (3) hire a patent attorney to prepare, file, and prosecute your patent application; and (4) request a professional prior art search. Those four tips are generally applicable to any subject matter, including chemical, mechanical, and software inventions.


Here we provide two additional tips for consideration before preparing a mechanical patent application. The term “mechanical invention” can refer to a variety of technologies, including medical devices, surgical instruments, hand tools, product packaging, exercise equipment, etc. To some in the patent world, the term mechanical invention functions as a catch-all: if an invention is not chemical, biotech, software, electrical, or a business method, then it is categorized as a mechanical invention. Below are a couple of tips to consider when preparing an application of this nature.

1) Include drawings of your invention, several drawings

Drawings may be the most important aspect of a mechanical patent application. In fact, for most applications the adage a picture is worth a thousand words rings true because many inventions are too complex to understand without drawings. Indeed, the relevant law states: “The applicant shall furnish a drawing where necessary for the understanding of the subject matter sought to be patented.”[i] Drawings are therefore required for most mechanical applications. As a rule of thumb, when there is any doubt as to whether a drawing should be included, it is advisable to include drawings because if the Patent Office determines that drawings are essential to understanding an application, then the filing date will not be established until the drawings are submitted.


There are additional benefits to including drawings with a patent application. For instance, any features shown in the original drawings but not described in the text of the specification can be later claimed without being considered impermissible “new matter.” In such a situation, the applicant will need to update the specification to include a description of any previously undescribed features that are added to an amended claim, but that description is not new matter because the drawings were provided on the filing date. Drawings, therefore, can provide cover for a draftsman’s initial ignorance—an unknowing that can subsequently be cured when a better understanding of the technology is developed during prosecution of the application.


It is important that drawings be submitted with the original disclosure because drawings submitted after the filing date cannot be relied on to overcome an examiner’s allegation of a non-enabling disclosure. In other words, if a patent examiner rejects one or more claims in an application because the specification fails to adequately describe how to make and use the invention, the Applicant cannot rely on drawings submitted after the filing date to rebut the examiner’s position. Additionally, drawings filed after the filing date cannot be relied on to argue the scope of a particular claim element.


Outside of prosecution, drawings may allow the relevant public to better understand a patented invention, and that understanding can help a layperson determine whether they might be infringing the patent. Armed with that knowledge, a potential infringer may decide to forge a different path in order to avoid litigation resulting from such an infringement.


It is further advisable to include multiple (non-redundant) drawings, including some that cover alternative embodiments of the patented invention. The disclosure of such alternatives can be offensive or defensive in nature. In this context, an offensive disclosure refers to a feature that is claimed in the application (and likely implemented in a commercial product)—a claim that could be asserted against a third party in an infringement action. A defensive disclosure, by contrast, refers to a feature that is unlikely to be claimed in the application. Although such a feature may not be claimed, the feature will be part of the application when it is published 18 months after the filing date, and the published application can serve as prior art to any later-filed applications. Accordingly, a disclosure included in an application for defensive purposes could prevent a third party from obtaining their own patent for a related item that could be a commercial threat to the marketed products protected by the claims in the application.

2) Try to quantify any improvements to the functionality of the invention

A new mechanical invention may be considered novel by the Patent Office and still subject to a prior art rejection based on a theory of obviousness. Obviousness rejections are the most common rejections issued by the Patent Office, but they can be rebutted via the submission of objective evidence of non-obviousness. When applicants submit such evidence, the patent examiner must reanalyze the rejection anew and balance the evidence of obviousness against the evidence of non-obviousness. The Manual of Patent Examining Procedure (MPEP)[ii] states: “Objective evidence relevant to the issue of obviousness must be evaluated by Office personnel. . . . Such evidence, sometimes referred to as ‘secondary considerations,’ may include evidence of commercial success, long-felt but unresolved needs, failure of others, and unexpected results.”[iii] Objective evidence is based on provable facts, not inventor bias, and the evaluator (e.g., patent examiner, judge) must consider such evidence from the perspective of a person having ordinary skill in the relevant art at the time of invention.


Generally, evidence of commercial success is not yet available at the time of filing a patent application. But the applicant may be aware of evidence derived from the prior art, such as evidence of a long-felt but unresolved need for the invention or evidence documenting the failure of others. Alternatively, a patent applicant may be aware of experimental evidence obtained from the laboratory, such as data or a result that was unexpected compared to data or trends disclosed in the prior art. More often than not, patent applicants rely on such evidence of “unexpected results” to rebut an obviousness rejection during patent prosecution. Indeed, such evidence may be the most important factor with respect to whether your invention is patentable or not.


Let’s consider a hypothetical example in which the structural features and primary function of a mechanical invention would have been considered obvious to a person skilled in the relevant art at the time of invention, and the patent examiner issues a rejection to each claim encompassing the invention. Having received an Office action with the rejection, the Applicant may come to the conclusion that the prior art references do support the examiner’s position. At this point, the Applicant must consider ways to overcome the rejection. One way to rebut an obviousness rejection is to submit evidence of unexpected results (sometimes with claim amendments). In this example, the Applicant realizes the effectiveness of the mechanical invention at carrying out the function was substantially better than what was expected at the time of invention. In some cases, the effectiveness of a device may be measured, and the results can be compared to the relative effectiveness of one or more existing devices in the relevant field. If the data obtained from such experiments does in fact show an unexpected result, then the data may be the basis for persuasively arguing why the rejection should be withdrawn and that a patent should be granted for the application claiming the device. Without the comparative data, the application was rejected and appeared to have little chance at ever being issued into a patent. With the comparative data, the rejection can be withdrawn, the application can be allowed, and the patent can be granted.


[i] 35 U.S.C. § 113.

[ii] Although the MPEP is not law, the examining procedures described therein must be followed by the patent examiners at the U.S. Patent & Trademark Office.

[iii] MPEP § 2141.

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