Patent Drawing Requirements

Patent drawings have changed over time. Patent drawings have gradually shifted from being hand-drawn masterpieces to machine-drawn printouts. Hand drawings are a lost art that we probably will never recapture. Many of the formal requirements associated with patent drawings have also changed over time. The Patent Office is much more lax in its acceptance of patent drawings. Nevertheless, there are many requirements which it still reviews drawings for and will occasionally reject just after filing, or which an Examiner will object to later on. This article describes some, but not all, of the things the Patent Office reviews when it comes to drawings, as well as some best practices for drawings.

• Orientation of the page – the page is supposed to be oriented with sheet numbering at the top, or if the sheet is turned so that it is in landscape, with the sheet numbering at the right. I don’t believe the Office is strict with this requirement, but it is supposed to be a requirement.
• Orientation of the numbers – the sheet number is the only number, letter, or other indicia which can have a different orientation than the others. If the sheet is to be read in portrait, then all reference characters should be oriented in that direction. If the sheet is to be read in landscape, then all reference characters should be oriented to facilitate reading in that direction, other than the sheet number. There should never be inconsistent orientation among the reference characters.
• Words – other than reference characters, there should be no other marks, indicia, or words on a sheet Legends can be used but are subject to the Office’s final approval.
• Black and white drawings are normally used and are preferred. Only in rare cases can color drawings be used. Photographs are almost never permitted. The exception is when color drawings or photographs are the “only practicable medium for illustrating the claimed invention.”
• Greyscale drawings can really destroy the quality of your patent drawings once uploaded to the Patent Office. If you scan drawings in as black and white only, and be sure they are not greyscale, do so. The Patent Office pixelates greyscale drawings in a way that can often lead to a drawings rejection a year or two down the road.
• Margins – each sheet must include a top margin of at least 1 inch, a left side margin of at least 1 inch, a right side margin of at least 5/8 inch, and a bottom margin of at least 3/8 inch.
• Character of lines, numbers, and letters. All drawings must be made by a process which will give them satisfactory reproduction characteristics. Every line, number, and letter must be durable, clean, black (except for color drawings), sufficiently dense and dark, and uniformly thick and well-defined. The weight of all lines and letters must be heavy enough to permit adequate reproduction. This requirement applies to all lines however fine, to shading, and to lines representing cut surfaces in sectional views. Lines and strokes of different thicknesses may be used in the same drawing where different thicknesses have a different meaning.
• English reference characters should be used except where other languages are commonly used (such as Greek alphabet letters to indicate angles)
• Lead lines. Lead lines are those lines between the reference characters and the elements or structures. They should be straight or curved and should be as short as possible. They must originate in the immediate proximity of the reference character and extend to the feature indicated. Lead lines must not cross each other. Lead lines are required for each reference character except for those which indicate the surface or cross section on which they are placed. Such a reference character must be underlined to make it clear that a lead line has not been left out by mistake. Lead lines must be executed in the same way as lines in the drawing. See paragraph (l) of this section.

I have rarely or never seen the Patent Office enforce these rules. Don’t rely on that, though – they may change their policy any time, or they may decide to pick on your application!

• The sheets must not contain frames around the sight (i.e., the usable surface), but should have scan target points (i.e., cross-hairs) printed on two cater-corner margin corners.
• Orientation of multiple figures on one page. All views of the drawing must be grouped together and arranged on the sheets without wasting space, preferably in an upright position, clearly separated from one another, and must not be included in the sheets containing the specifications, claims, or abstract.
• Exploded views. Exploded views, with the separated parts embraced by a bracket, to show the relationship or order of assembly of various parts are permissible. When an exploded view is shown in a figure which is on the same sheet as another figure, the exploded view should be placed in brackets.