Inspection Checklist

Inspection Checklist for Utility Patent Drawings

Use this chapter as a pre-filing checklist for utility patent drawings.
Where helpful, references to other chapters are shown in parentheses—for example:
(see “Figure Standards,” §2 Spacing Between Figures).

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1. Media & Source Artwork

1.1 Raster vs. Vector

• [ ] Do you have raster images (scans, JPEG/PNG) of black line drawings?
• [ ] Are all lines smooth, solid, and dark enough? (see “Line Quality Standards,” §2 Character of Lines)
• [ ] Are all characters at least 3.2 mm (⅛", ~12 pt) and clearly readable? (see “Character Size Standards,” §1)

• [ ] If yes to both, the raster image may be used.
  If no, redraw as a clean vector line drawing.

• [ ] Do you have color raster images?

• [ ] Have you converted them to black-and-white?
• [ ] After conversion, are line and text quality still acceptable?
• [ ] If no, redraw as vector line drawings.

1.2 Fills, Photos, and Prototypes

• [ ] Are there any gray, color, or solid-black fills used to show shape instead of lines?
• [ ] Convert them to outline + hatching/shading lines only (no solid fill), unless they are intentional color claims. (see “Line Quality Standards,” §3 Hatching & Shading)
• [ ] Are there any photos or bitmap images that could be shown as line art?
• [ ] Trace or redraw them as vector black line drawings.
• [ ] Are drawings based on rough prototype photos?
• [ ] Have you simplified/idealized parts so they look like clean engineered views, not rough product photos?

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2. Sheet Setup: Paper, Margins, and Numbering

2.1 Paper Size & Margins

(see “Page & Margin Standards” chapter)

• [ ] Are all sheets the same size (Letter 8.5"×11" or A4 210×297 mm)?
• [ ] Does every sheet respect the minimum portrait margins (imaginary, not drawn)?
• [ ] Top ≥ 1 in (25 mm)
• [ ] Left ≥ 1 in (25 mm)
• [ ] Right ≥ 0.6 in (15 mm)
• [ ] Bottom ≥ 0.4 in (10 mm)
• [ ] For landscape sheets, are margins applied as if the sheet were in portrait?
  (Top 1 in, bottom 0.6 in, left 0.4 in, right 1 in.)

2.2 Sheet Numbering

• [ ] Are sheets numbered in Arabic numerals using the format:
  sheet_number / total_sheets (e.g., 1/4, 2/4, 3/4, 4/4)?
• [ ] Is the sheet number placed:
• [ ] On the top center, just under the top margin, or
• [ ] In the upper-right of the sight if the center is occupied by a figure?
• [ ] For landscape sheets, is the sheet number:
• [ ] Placed on the right side of the sheet,
• [ ] Oriented as though the sheet were in portrait?

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3. Figure Layout, Orientation, and Numbering

(see “Figure Standards” & “Figure Number Standards”)

3.1 Orientation & Spacing

• [ ] Is each figure upright relative to the top of the sheet (portrait or landscape)?
• [ ] On landscape sheets:
• [ ] Are figures and text rotated into landscape, while sheet numbers stay in portrait orientation?
• [ ] Are figures far enough apart so their lines and parts cannot be confused?
• [ ] Are there no construction/projection lines connecting separate figures
  (except for electrical waveforms showing timing)?

3.2 Size and Arrangement

• [ ] Are figures made as large as possible within the margins without crowding?
• [ ] Are figures arranged so:
• [ ] Lower-numbered figures appear on earlier sheets.
• [ ] Figure numbers increase from sheet to sheet (do not restart at FIG. 1).
• [ ] On each sheet, figures generally progress left-to-right, top-to-bottom.

3.3 Figure Numbers & Prior Art Labels

(see “Figure Number Standards”)

• [ ] Are all figures numbered in consecutive Arabic numerals beginning with FIG. 1?
• [ ] Is each figure prefixed with “FIG.” or “Fig.” (e.g., “FIG. 3”)?
• [ ] Does each figure number refer to one specific figure only?
• [ ] If the figure shows prior art, is it labeled “Prior Art” next to or just below the figure number
  (e.g., FIG. 1 — Prior Art)?

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4. Special View Types

4.1 Sectional Views

(see “Figure Standards,” §11 Sectional Views)

• [ ] Where internal structure must be shown, are sectional views provided?
• [ ] On the corresponding general view:
• [ ] Is there a broken cutting plane line?
• [ ] Are arrows at each end showing the direction of sight?
• [ ] Is the section figure number written next to the arrows (e.g., “2” or “2–2”)?
• [ ] In each sectional view:
• [ ] Are cut surfaces hatched (e.g., at ~45°)?
• [ ] Are adjacent parts distinguished by changes in hatch angle/spacing?

4.2 Partial Views & Tiled Figures

(see “Figure Standards,” §9 Partial Views)

• [ ] If a figure is too large for one sheet, is it split into partial views?
• [ ] For mechanical views:
• [ ] Are partial figures arranged so sheets can be tiled without ambiguity (side-by-side, top-to-bottom, or grid)?
• [ ] Are dot–dot–dash (phantom) lines used along broken edges?
• [ ] Are all partial sheets labeled with the same base figure number plus letter suffixes (e.g., FIG. 3A, FIG. 3B)?
• [ ] For flowcharts/diagrams:
• [ ] Are connector circles with letters (A, B, C…) used to show continuation?
• [ ] Are matching connectors used on the continuation sheet?

4.3 Shortened (Broken) Figures

(see “Figure Standards,” §10 Shortened Figures)

• [ ] For very long objects, are they shortened instead of squeezed into tiny scale?
• [ ] Are breaks shown with standard break symbols (zig-zag / phantom) and no essential detail removed?

4.4 Exploded Views & Brackets

(see “Figure Standards,” §8 Exploded Views)

• [ ] Where assembly relationships are important, are exploded views provided?
• [ ] Are parts separated enough to show how they fit?
• [ ] Are projection lines used as needed to indicate alignment?
• [ ] If the figure has disconnected components:
• [ ] Are brackets used to “embrace” all parts that belong to the same figure, even when not exploded?

4.5 Enlarged Views

• [ ] Are enlarged views provided for small or complex areas?
• [ ] In the general view:
• [ ] Is the enlarged region surrounded by a dashed circle or boundary?
• [ ] Does the circle carry a reference indicating the enlarged figure number?
• [ ] In the enlarged figure:
• [ ] Is the same circle/boundary shown around the enlarged area?

4.6 Moving Parts & Motion Arrows

(see “Figure Standards,” §12 Moving Parts)

• [ ] For mechanisms with moving parts:
• [ ] Are arrows used to show directions of motion (linear and rotational)?
• [ ] If multiple arrows appear, are they distinguished with different reference numbers?
• [ ] Are phantom lines or additional figures used appropriately to show alternate positions?

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5. Reference Numbers & Lead Lines

(see “Reference Number Standards” & “Lead Line Standards”)

5.1 Reference Numbers

• [ ] Does every part mentioned in the specification have a reference number in the drawings?
• [ ] Does every numbered part in the drawings appear in the written description?
• [ ] Is each part given one unique number (same number for same part in all figures)?
• [ ] Are identical, interchangeable parts given the same number only when not distinguished in text?
• [ ] Are letters used only for:
• [ ] non-tangible elements (e.g., airflow A) or
• [ ] standard electronics notation (R1, C2, etc.)?
• [ ] Are all characters (numbers & letters):
• [ ] in a simple, non-ornate font (no script or decorative styles)?
• [ ] at least 3.2 mm (⅛", ~11 pt) high, except subscripts/superscripts?

5.2 Placement of Reference Numbers

• [ ] Are numbers placed close to the part they identify, but not overlapping it?
• [ ] Are they positioned far enough from other parts to avoid ambiguity?
• [ ] Are they preferably outside the figure where possible to reduce clutter?
• [ ] Are they never drawn over any object or hatch lines?
  (White background or hatch gaps are used where numbers lie on cross-sections.)

5.3 Lead Lines & Underlines

• [ ] Does every reference number connect to its feature via a lead line or underline?
• [ ] Are lead lines:
• [ ] straight or smoothly curved
• [ ] clearly pointing to the part, with the end touching the object
• [ ] not crossing or overlapping other lead lines whenever possible
• [ ] positioned at a distinct angle from nearby shape edges to avoid confusion?
• [ ] If a part appears in multiple figures, are separate lead lines and numbers used in each figure (no single number with two lead lines connecting figures)?
• [ ] Where numbers lie directly on a surface or section, is a simple underline used instead of a lead line, with hatching interrupted to leave room—used sparingly?

5.4 Arrows

• [ ] Are arrows used correctly to:
• [ ] designate a group of parts with a single number,
• [ ] indicate the cutting plane and direction for sectional views,
• [ ] or show movement?
• [ ] Where multiple arrows appear, are they given distinct reference numbers to avoid confusion?

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6. Line Quality, Types, and Hatching

(see “Line Quality Standards”)

6.1 Line Quality

• [ ] Are all drawings in black lines (no gray anti-aliasing or colored lines)?
• [ ] Are all lines:
• [ ] Dense and dark enough to survive photocopying and reduction?
• [ ] Uniform in thickness along their length (except intentional thick vs. thin line use)?
• [ ] Smooth, not jagged, with no feathered or pixelated edges?
• [ ] Unbroken, with no random gaps?

6.2 Line Types

• [ ] Are allowed line types used correctly:
• [ ] Solid for visible edges and shading lines
• [ ] Dashed for hidden edges
• [ ] Phantom (dash–dot–dot–dash) for parts not claimed or for continuation edges
• [ ] Dash–dot–dash projection lines (e.g., in exploded views) when needed?
• [ ] Are broken line styles used consistently across all figures?

6.3 Hatching & Shading

• [ ] Are hatch lines thin, evenly spaced, and at a consistent angle (typically ~45°)?
• [ ] Are adjacent parts in section distinguished by:
• [ ] different hatch angles, or
• [ ] different spacing/offsets?
• [ ] Are there no large solid black areas except bar graphs or explicit color-claim graphics?

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7. Prohibited Elements

(see “Prohibited Elements” chapter)

• [ ] No scale notes such as “Actual Size” or “Scale 1:2.”
• [ ] No morally offensive or irrelevant images.
• [ ] No trademarks/service marks (e.g., logos) unless proprietary rights are established.
• [ ] No centerlines drawn solely to show axes of circles (rarely enforced but best avoided).
• [ ] No circles or brackets surrounding reference numerals.
• [ ] No descriptive phrases like “ON/OFF SWITCH” or “SERATED SURFACE” outside of allowed contexts:
• [ ] Flowcharts
• [ ] Block diagrams
• [ ] Tables and graphs where labels are indispensable.
• [ ] No copyrighted artwork used without ownership/permission.
• [ ] No lines connecting separate figures, except between electrical waveforms to show timing.

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8. Quality-Control Questions (Final Review)

Use these questions for a final QC pass or to instruct an assistant:

• [ ] Are all figures aligned and evenly spaced, with consistent margins and layout?
• [ ] Are figure numbers, sheet numbers, labels, and line types consistent across pages?
• [ ] Are all text elements:
• [ ] the approved simple font (e.g., Arial-like, non-ornate)?
• [ ] at or above minimum size?
• [ ] black only, with no color or gray?
• [ ] Do reference numbers and text fit within shapes or areas without touching borders?
• [ ] Are line breaks, spacing, and alignment clean and readable?
• [ ] Are lead lines:
• [ ] clearly distinguishable from object edges,
• [ ] not crossing each other unnecessarily,
• [ ] not shared between separate figures?

Special Cases

• [ ] Dimensions are omitted unless critical to understanding or distinguishing from prior art.
• [ ] Exploded views:
• [ ] Use brackets and/or projection lines correctly.
• [ ] Long objects:
• [ ] Properly shortened with break symbols, or split into partial views if needed.
• [ ] Sectional views:
• [ ] Have cutting plane indicators, arrows, and varying hatching where appropriate.
• [ ] Enlarged views:
• [ ] Have clear callouts and matching figure numbers.
• [ ] Special content types (if present) all comply with line, text, and numbering rules:
• [ ] electronic schematics
• [ ] block diagrams & flowcharts
• [ ] graphs & waveforms
• [ ] chemical formulas
• [ ] tables
• [ ] screenshots / GUI figures
• [ ] mixed symbolic + physical drawings

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By running each drawing set through this checklist—and cross-referencing the detailed rules in the other chapters—you can systematically catch most USPTO drawing defects before filing and keep your utility figures consistent, clear, and examination-ready.