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Functional Block Diagram

For the purpose of this report, a simplified electric toothbrush block diagram shows the logic and translation use cases. Simplified Block Diagram for Personal Care Electronics shows an example of this block diagram. Each red block has an associated use-case document. Table 1 and Table 2 provide links to the associated use-case document. For a complete block diagram, see the interactive online end equipment reference diagram for an electric toothbrush. This block diagram can be used in other electric personal care devices using internal motors, such as electric razors.

Figure 1 Simplified Block Diagram for Personal Care Electronics

Logic and Translation Use Cases

Each use case is linked to a separate short document that provides additional details including a block diagram, design tips, and part recommendations. The nearest block and use-case identifiers are listed to match up exactly to the use cases shown in the provided simplified block diagram.

Shifting a Device Between Modes

Many electric personal care devices have multiple modes of operation, such as different power or speed levels. These modes are often controlled separately from the device power button. Turning the device on sets the device to a pre-defined state, from which a separate button can be used to switch the device mode.

There are multiple possible configurations of this setup that allow for different numbers of modes and control inputs. For these configurations, each mode output is tied to the enable of a motor driver. Only one of the mode outputs can be active at a time. All other mode outputs are low. Triggering the circuit causes the active mode output to change.

Figure 2 Separate Inputs for Mode Control and Device Enable

• The left image shows a configuration supporting 2 modes and the right image shows a configuration supporting more than 2 modes
• These configurations default to mode 1 being active when the device is turned on
• Expanding the number of modes can be done by expanding the logic between the shift register output an input. An example expanding the number of modes from 3 to 4 is shown.

Figure 3 Single Input for Mode Control and Device Enable

• This configuration has a "mode 0" in which all of the modes are turned off. The device defaults to mode 0 and returns to mode 0 after cycling through the other modes.
• Expanding the number of modes can be done by expanding the logic between the shift register output and input. An example expanding the number of modes from two to three is shown.

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