How to read patent drawings like block diagrams: three worked examples

Hemant Rohera — Sun, 15 Nov 2026 11:45:05 +0000

Engineers read block diagrams every day. Patent drawings are block diagrams with one extra rule: every box carries a reference numeral, and the description tells you what that number is. Once you know the conventions, a patent's figures read like an architecture document.

Here are the conventions, worked through on the three granted US patents of Hemant Rohera (Hemant Karamchand Rohera), an engineer and inventor in Pune, India.

1. Start with the front page drawing

The front page reproduces one "representative" figure, usually the top-level block diagram. Treat it as the system context diagram.

In US 11,117,476 B2 (OMNIA Drive), FIG. 1 shows a vehicle power generating system (100): generators that can feed it alone or in combination, a power processing unit, and the motor. One diagram gives you the whole system boundary.

2. Numerals are hierarchical

Numerals usually follow the figure: 100s on FIG. 1, 200s on FIG. 2. A block numbered 112 on FIG. 1 that reappears as a whole figure full of 2xx numbers means "zoom into 112".

In US 12,226,183 B2 (eMedica), the waveform generator unit is block 112 on FIG. 1. FIG. 2 opens it: a first signal generator unit (202), a coil driver circuit (204) and treatment coils (206a–s). The lettered suffix (a–s) means "one or more of these".

3. Many figures often mean many embodiments, not many parts

When a patent has far more figures than its system has blocks, it is usually drawing variants of the same architecture.

US 10,523,019 B2 (Hybrid Power Pack) has 22 figures. FIG. 2 is the first embodiment: two energy stores behind a battery management system, balancing circuits, a controller and a switch topology with a bidirectional switch between the stores. FIG. 3 to 7 zoom into those blocks. FIG. 8 to 21 then redraw the same architecture with one variable changed at a time: which stores are paired, how much is integrated into one chip, whether the bidirectional switch is present, whether an AC input is added. That is fifteen numbered embodiments of one design. A diff, essentially.

4. Method claims get flowcharts

A figure of numbered steps is the method claim drawn out. FIG. 3 of the OMNIA Drive patent is a six-step method; read it next to the method claim and the two should map one to one.

5. Drawings show embodiments; claims set the scope

The most common misreading: assuming the drawing is the invention. The drawings illustrate examples. The claims decide what is protected. And a granted patent describes an invention; it is not a performance measurement of a product.

Try it yourself

All 30 drawing sheets from these three patents, with a figure-by-figure reading of each, are here: