Patent Drawings: Understanding the Significance of Replacement and New Sheets

Patent offices can reject patent applications due to multiple reasons. One of the most common reasons for rejection is an error in patent drawings. While responding to the office actions (OAs) received after such rejections, applicants usually need to modify or add new figures in the drawings. The following article explains the type of sheets that applicants must append to patent drawings for addition or replacement of figures.

What is a Replacement Sheet and When is it Used?

A replacement sheet is a sheet that is used when the figures with defects are replaced with the modified figures. As per the U.S. Patent and Trademark Office (USPTO), every replacement sheet of a patent drawing must comply with § 1.84 and should include all the figures that appear in the original version of the sheet. The words “Replacement Sheet” must be written on the sheet that has been added as a replacement to the old sheet.

Case Study on Usage of Replacement Sheet after an Office Action

Fig.1: Office Action Received from the Patent Examiner

In the above OA received by the applicant, errors were marked by the examiner to highlight the required changes. The main issue in the drawing was the extension of lines in some areas that were neither a part of the claim nor were providing correct details of the invention’s parts. The examiner had asked the applicant to add replacement sheets wherever required and remove the extending lines (see Fig .2).

Fig.2: The Patent Drawing Issue Highlighted by the Examiner

Our Response to the Office Action

After reading the OA and the requirement of the examiner, we excluded the lines that were passing through the invention’s part. We also made other figures consistent with these changes. For ensuring this, we created a consistency sheet that helps to compare each part with other parts in all drawing views.

Fig.3: Modified Patent Drawing in Perspective View

It is important to note that the applicant must respond to the OA in the same layout and sheet size (letter or A4) as that of the original drawing submitted to the patent office. Since the applicant received the informal patent drawings in landscape layout and A4 size, our team responded using sheets with the same layout and size.

As per the patent office guidelines, the modified figures should be placed (on the sheets) within the margins, i.e., top: 2.5 cm, leftside: 2.5 cm, right side: 1.5 cm, and bottom: 1 cm. Based on these guidelines, the word “FIG.” was written at the bottom while the words “Replacement Sheet” were added to the centre of the top margin in portrait orientation. Since the page numbers were excluded in the OA, our team excluded the page numbers and redrew the figure by keeping all the patent drawing rules in mind. After the applicant filed the amended drawings, he got approval from the examiner in one go.

Common Issues Requiring the Addition of Replacement Sheets & Their Solutions

1. Inconsistency of parts or shading in design drawings

This problem occurs when the part shown in the perspective view is not visible in a similar view in another figure. To tackle this issue, applicants must create a consistency sheet for ensuring consistency of parts and updating them wherever required. This step should be followed by addition of replacement sheets.

2. Incorrect text height

When the textual height of drawings is less or more than the one prescribed by the patent office’s rules and regulations, applicants must change the height to 3.2 mm and also add a replacement sheet in place of the incorrect sheet.

3. Coloured images

Appending coloured images to the patent application can also lead to patent rejection as coloured images are not allowed by patent offices. This rejection can be overcome by using either black & white line drawings or greyscale images. After modifying the images, applicants must add a replacement sheet in place of the incorrect sheet.

What is a New Sheet and When is it Needed?

A new sheet is added to an OA response when the drawings are rejected due to lack of clarity. This can be due to the examiner’s inability to understand the drawing or visibility issues of an invention’s part in any of the drawing views that make it difficult to understand the exact shape, depth, or height of that part. So, it is suggested to either keep that part disclaimed or add a new sheet with that part projected correctly, i.e., projected with correct dimensional and surface details such as depth, height or contours. In essence, applicants must add a “New Sheet” when they add a new matter to the drawings.

Case Study on Usage of New Sheet after an Office Action

A client engaged Sagacious IP for filing the correct response to an OA that it received on an erroneous drawing, i.e., drawing with visibility issues related to an invention’s part. The reason for its rejection is that the ellipses mentioned in the patent draft/specification are missing in the drawing (see Fig. 4).

Fig.4: A Drawing that Does not Show a Part Mentioned in the Patent Specification

Solution to this Issue

To resolve the issue, our team added the required ellipses to the patent drawing. Since this addition made the drawing different from what it was at the time of filing, it was considered as a new matter. So, the team also added a new sheet.

Fig.5:  New Drawing with all Parts mentioned in the Patent Specification


Filing patent applications while ignoring the drawing rules of the concerned patent office leads to issuance of OAs. When responding to these OAs, it is necessary to add replacement or new sheets wherever required. Since adding these sheets while keeping the patent office rules in mind can be slightly tricky, it is advisable to hire experienced patent illustrators.

In case you are looking for patent drawing services, getting expert assistance is crucial. Sagacious IP offers patent drawings that are prepared keeping the drawing rules of the different patent offices in mind. Click here to know more about this service.

  • Punit Mehta (Illustration) and The Editorial Team

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