HMI Rocker Switch With Hall-Effect Switches

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1 Introduction

Working with complex machines such as vehicles, involves various tactile controls. Often these controls provide three states of operation, such as initiating a car door to lock, unlock, or remain idle and also when raising, lowering, or maintaining:

window position such as found on a car door
speed such as found in the cruise control of a car
the volume of the radio

In addition to these, there are likely many more possible applications and these need not be strictly relevant to an automobile. One particular type of tactile control that can be utilized for such state selection is the Rocker Switch. This document dives into the basic operating principles and shows the design process for one possible version of a rocker switch. Challenges in the design process are also documented.

Figure 1-1 summarizes the design flow presented in this document.

Figure 1-1 Design Flow

2 Design Process

2.1 Mechanical Implementation

Typically, the design begins with defining a system that executes a particular set of actions. In this case, the goal is a three-state switch in which there are two action states achieved when the user applies some force and another resting state, when the user applies no force or returns the switch to the default position. This actually might be achieved with multiple different styles of switch and is therefore subjective to the user preference, aesthetic, space, or cost. Figure 2-1 shows three possible mechanical options. This document explores what is necessary to make a three-state switch with the bottom option, the rocker switch.

Figure 2-1 Mechanical Options

A rocker switch can be generalized into four basic mechanical components: a base, axle, springs, and a rocker. In this case the base holds the axle and has cantilevers that serve as springs for returning the rocker back to the resting state when the user is not applying force. While these cantilevers are not the primary focus in this design, note that traditional metal spring alternatives were intentionally avoided as many are typically composed of iron which can influence the magnetic field shape from a nearby magnet and thereby complicate design.

Figure 2-2 Mechanical Implementation