According to 37 C.F.R. § 1.81, all utility and design applications require the submission and acceptance of formal drawings. Information on drawing requirements is based substantially on 37 C.F.R. § 1.84. There are two acceptable categories for presenting drawings with utility patent applications: black ink (black and white) and color.

Black and white drawings are normally required. On occasion, color drawings may be necessary as the only medium by which the subject matter sought to be patented in a patent application is disclosed. The USPTO will accept color drawings in utility patent applications and statutory invention registrations only after granting a petition explaining why the color drawings are necessary and payment of the requisite government fee.

Photographs are not ordinarily permitted in utility patent applications. The USPTO will accept black and white photographs in utility patent applications only in applications in which the invention is not capable of being illustrated in an ink drawing or where the invention is shown more clearly in a photograph. Only one set of black and white photographs is required. Furthermore, no additional processing fee is required.

Photographs have the same sheet size requirements as other drawings. The photographs must be of sufficient quality so that all details in the drawing are reproducible in the printed patent or any patent application publication.

Color photographs will be accepted in utility patent applications if the conditions for accepting color drawings have been satisfied.

A list of drawing requirements will include:

• Identification of Drawings
• Graphic Forms in Drawings
• Paper
• Views
• Exploded Views
• Partial Views
• Sectional Views
• Alternate Position
• Modified Forms
• Arrangement of Views
• Front Page View
• Scale
• Character of Lines, Numbers, and Letters
• Shading
• Symbols
• Legends
• Numbers, Letters, and Character References
• Lead Lines and Arrows
• Copyright or Mask Work Notice
• Numbering of Sheets of Drawing Views
• Security Markings
• Corrections

Holes
The drawing must contain as many views as necessary to show the invention. The views may be plan, elevation, section, or perspective views. Detailed views of portions of elements, on a larger scale if necessary, may also be used. All views of the drawing must be grouped together and arranged on the sheet(s) 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. Views must not be connected by projection lines and must not contain center lines. Waveforms of electrical signals may be connected by dashed lines to show the relative timing of the waveforms.

Patent Drawing - 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.

Patent Drawing - Partial Views
When necessary, a view of a large machine or device in its entirety may be broken into partial views on a single sheet, or extended over several sheets if there is no loss in facility of understanding the view. Partial views drawn on separate sheets must always be capable of being linked edge to edge so that no partial view contains parts of another partial view. A smaller scale view should be included showing the whole formed by the partial views and indicating the positions of the parts shown. When a portion of a view is enlarged for magnification purposes, the view and the enlarged view must each be labeled as separate views.

Where views on two or more sheets form, in effect, a single complete view, the views on the several sheets must be so arranged that the complete figure can be assembled without concealing any part of any of the views appearing on the various sheets.

A very long view may be divided into several parts placed one above the other on a single sheet. However, the relationship between the different parts must be clear and unambiguous.

Patent Drawing - Sectional Views
The plane upon which a sectional view is taken should be indicated on the view from which the section is cut by a broken line. The ends of the broken line should be designated by Arabic or Roman numerals corresponding to the view number of the sectional view, and should have arrows to indicate the direction of sight. Hatching must be used to indicate section portions of an object, and must be made by regularly spaced oblique parallel lines spaced sufficiently apart to enable the lines to be distinguished without difficulty. Hatching should not impede the clear reading of the reference characters and lead lines. If it is not possible to place reference characters outside the hatched area, the hatching may be broken off wherever reference characters are inserted. Hatching must be at a substantial angle to the surrounding axes or principal lines, preferably 45 .

A cross section must be set out and drawn to show all of the materials as they are shown in the view from which the cross section was taken. The parts in cross section must show proper material(s) by hatching with regularly spaced parallel oblique strokes; the space between strokes being chosen on the basis of the total area to be hatched. The various parts of a cross section of the same item should be hatched in the same manner and should accurately and graphically indicate the nature of the material(s) illustrated in cross section.

The hatching of juxtaposed different elements must be angled in a different way. In the case of large areas, hatching may be confined to an edging drawn around the entire inside of the outline of the area to be hatched. Different types of hatching should have different conventional meanings as regards the nature of a material seen in cross section.

Patent Drawing - Alternate Position
A moved position may be shown by a broken line superimposed upon a suitable view if this can be done without crowding; otherwise, a separate view must be used for this purpose.

Patent Drawing - Modified Forms
Modified forms of construction must be shown in separate views.

Patent Drawing - Arrangement of Views
One view must not be placed upon another or within the outline of another. All views on the same sheet should stand in the same direction and, if possible, stand so that they can be read with the sheet held in an upright position. If views wider than the width of the sheet are necessary for the clearest illustration of the invention, the sheet may be turned on its side so that the top of the sheet is on the right-hand side, with the appropriate top margin used as the heading space. Words must appear in a horizontal, left-to-right fashion when the page is either upright or turned so that the top becomes the right side, except for graphs utilizing standard scientific convention to denote the axis of abscissas (of X) and the axis of ordinates (of Y).

Patent Drawing - Front Page View
One of the views should be suitable for inclusion on the front page of the patent application publication and patent as the illustration of the invention.

Scale
The scale to which a patent drawing is made must be large enough to show the mechanism without crowding when the patent drawing is reduced in size to two-thirds in reproduction. Indications such as "actual size" or "scale 1/2" are not permitted on the patent drawings since these lose their meaning with reproduction in a different format.

Character of Lines, Numbers, and Letters
All patent 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.

Shading
The use of shading in views is encouraged if it aids in understanding the invention and if it does not reduce legibility. Shading is used to indicate the surface or shape of spherical, cylindrical, and conical elements of an object. Flat parts may also be lightly shaded. Such shading is preferred in the case of parts shown in perspective, but not for cross sections. See discussion of sectional views above. Spaced lines for shading are preferred. These lines must be thin, as few in number as practicable, and they must contrast with the rest of the drawings. As a substitute for shading, heavy lines on the shade side of objects can be used except where they superimpose on each other or obscure reference characters. Light should come from the upper left corner at an angle of 45 . Surface delineations should preferably be shown by proper shading. Solid black shading areas are not permit ted, except when used to represent bar graphs or color.

Symbols
Graphical drawing symbols may be used for conventional elements when appropriate. The elements for which such symbols and labeled representations are used must be adequately identified in the specification. Known devices should be illustrated by symbols which have a universally recognized conventional meaning and are generally accepted in the art. Other symbols which are not universally recognized may be used, subject to approval by the USPTO, if they are not likely to be confused with existing conventional symbols, and if they are readily identifiable.

Legends
Suitable descriptive legends may be used, or may be required by the examiner, where necessary for understanding of the patent drawing, subject to approval by the USPTO. They should contain as few words as possible.

Numbers, Letters, and Reference Characters
The English alphabet must be used for letters, except where another alphabet is customarily used, such as the Greek alphabet to indicate angles, wavelengths, and mathematical formulas.

Reference characters (numerals are preferred), sheet numbers, and view numbers must be plain and legible, and must not be used in association with brackets or inverted commas, or enclosed within outlines (encircled). They must be oriented in the same direction as the view so as to avoid having to rotate the sheet. Reference characters should be arranged to follow the profile of the object depicted.

Numbers, letters, and reference characters must measure at least 0.32 cm. (1/8 inch) in height. They should not be placed in the drawing so as to interfere with its comprehension. Therefore, they should not cross or mingle with the lines. They should not be placed upon hatched or shaded surfaces. When necessary, such as indicating a surface or cross section, a reference character may be underlined and a blank space may be left in the hatching or shading where the character occurs so that it appears distinct.

The same part of an invention appearing in more than one view of the drawing must always be designated by the same reference character, and the same reference character must never be used to designate different parts.

Reference characters not mentioned in the description shall not appear in the patent drawings. Reference characters mentioned in the description must appear in the patent drawings.

Lead Lines and Arrows
Lead lines are those lines between the reference characters and the details to which they refer. Such lines may 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.

Arrows may be used at the ends of lines, provided that their meaning is clear, as follows:

• on a lead line, a freestanding arrow to indicate the entire section toward which it points;
• on a lead line, an arrow touching a line to indicate the surface shown by the line looking along the direction of the arrow; or
• to show the direction of movement.

Copyright or Mask Work Notice
A copyright or mask work notice may appear in the patent drawing, but must be placed within the sight of the drawing immediately below the figure representing the copyright or mask work material and be limited to letters having a print size of 0.32 cm. to 0.64 cm. (1/8 to 1/4 inches) high. The content of the notice must be limited to only those elements provided for by law. Inclusion of a copyright or mask work notice will be permitted only if the authorization language set forth in 37 C.F.R. § 1.71(e) is included at the beginning of the specification.

Numbering of Sheets of Drawings and Views
The sheets of patent drawings should be numbered in consecutive Arabic numerals, starting with 1, within the sight (the usable surface). These numbers, if present, must be placed in the middle of the top of the sheet, but not in the margin. The numbers can be placed on the right-hand side if the drawing extends too close to the middle of the top edge of the usable surface. The drawing sheet numbering must be clear and larger than the numbers used as reference characters to avoid confusion. The number of each sheet should be shown by two Arabic numerals placed on either side of an oblique line, with the first being the sheet number and the second being the total number of sheets of drawings, with no other marking.

The different views must be numbered in consecutive Arabic numerals, starting with 1, independent of the numbering of the sheets and, if possible, in the order in which they appear on the drawing sheet(s). Partial views intended to form one complete view, on one or several sheets, must be identified by the same number followed by a capital letter. View numbers must be preceded by the abbreviation FIG. Where only a single view is used in an application to illustrate the claimed invention, it must not be numbered and the abbreviation FIG. must not appear.

Numbers and letters identifying the views must be simple and clear and must not be used in association with brackets, circles, or inverted commas. The view numbers must be larger than the numbers used for reference characters.

Security Markings
Authorized security markings may be placed on the drawings provided they are outside the sight, preferably centered in the top margin.

Corrections
Any corrections on patent drawings submitted to the USPTO must be durable and permanent.

Holes
No holes should be made by the applicant in the drawing sheets. Rather than use of a staple, a non-hole producing binder clip should be used.