Line Styles and Conventions in Patent Drawing


A patent drawing made for an invention can increase the chances of your application being granted manifold. However, a patent drawing is a very structured document wherein you will have to put every element as per the specified norms. The conventions in patent drawing are set and they need to be followed for successfully serving the purpose of patent drawings. Even while adding a line you need to follow the guidelines meant for line styles in a patent drawing. Some of the important line types those we can use in drawings for patents are Solid Line, Phantom Line, Projected Line, Hidden Line, and Boundary Line.

These lines help the patent examiner to clearly understand the invention and get an idea of how the invention looks like to improve the scope of getting the patent. The patent drawings serve the purpose of explaining the invention to the patent examiner in an easier that the text can’t explain and therefore the purpose if served in a better way when different lines are added to these drawings.

Every patent office has their own set of guidelines to prepare patent drawings and these guidelines are to be abided in order to set the purpose of the patent drawings in right direction. These are conventions of patent drawing that must be followed for serving the purpose of it.

Also read: When is a Paten Drawing Needed?

With this article, we have come up with some important facts pertaining to line styles and conventions in patent drawings.

Thick Continuous: These are visible lines used on each view including arcs/circles/curves/title block and border.

Thick dashes: Like “Thick Continuous” lines these HIDDEN LINES too are used on each view. Dashes start and end with contact to a visible or hidden line.

Thin continuous: “THIN CONTINOUS LINES” are used for dimensioning lines, projection lines, leaders, letterform used in the title block.

Thin chain: Thin chain lines are CENTRE LINES used in the axis of solid forms; pitch lines (think roof line) etc.

Also read: How Patent Illustrator can Help Companies in their Patent Drafting Process?

Points to consider while using these lines:

  • All lines on any particular patent drawing should be either in pencil or ink, but not a mixture of both.
  • In case you are creating a patent drawing using a computer use the following line thickness:
Line styleMM
VISIBLE LINES used on each view; includes arcs/circles/curves/title block and border0.35
HIDDEN LINES used on each view. Dashes start and end with contact to visible or hidden lines0.35
THIN CONTINUOUS used for dimensioning lines, projection lines0.18
Center LINES, axis of solid forms, pitch lines0.18
  • The length and spacing of dashes should be consistent on any particular drawing(s)
  • Chain lines should start and finish with a long dash, but not too long, in a cutting plane.
  • When Centre-lines define Centre points they should cross one another at dash portions of the line.

Points to follow while doing dimension placement

  • ensure that they have dimensions for the height, width, and depth
  • ensure that they have included all crucial dimensions that allow the object to be interpreted
  • Use dimension where the shapes are shown and try to avoid dimensioning hidden lines
  • space dimension lines so that the dimensions are not overcrowded
  • Do not over-dimension the work as it can lead to confusion and an untidy drawing.

Services at PatSketch

At PatSketch, we draft your drawing systematically in accordance with the patent office rules and guidelines no matter how much complex your drawing is. Though seldom required, we do your iterations till you are satisfied. To have a look at our work, download few free samples available on our website or visit our website for pricing.

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