What Is a Leaf Switch?
Leaf switches are switches that conduct electricity by physically bringing two or three thin copper plates into contact with each other.
Like other types of switches, they have an ON-OFF or ON-ON function.
Some leaf switches have exposed contacts, while others are fitted with plastic covers. Both are simple in construction and have few parts, so if contact failure occurs, they can be restored with simple maintenance such as polishing the contacts and applying a contact revival agent.
Uses of Leaf Switches
Leaf switches are generally used to detect the position of the pickup body or motor of a CD player. Leaf switches with increased dust resistance and longer life are also used in pushbutton switches for elevators and other equipment.
When the pickup body moves to the end, it contacts the leaf switch and the contact turns ON. This controls the pickup body from moving any further when electricity flows through it. If the leaf switch has poor contact, it cannot detect that the pickup body has moved to the end, so it tries to move forcibly, which may cause a failure.
Principle of Leaf Switches
Leaf switches consist of two or three thin copper plates fixed to the base in a long protruding position. At the end of the copper plates is a contact point and on the other side is a terminal. The thin copper plates bend easily even with light force, and when the contact points come into contact with each other, electricity flows. By detecting this current on the circuit side, it is possible to detect the position of the desired object.
In the case of a leaf switch with two copper plates, the switch is OFF when they are far apart and ON when they are in contact with each other; in the case of a leaf switch with three plates, the central copper plate is originally in contact with one side, allowing the switch to flip where electricity flows.
Leaf switches have a simple construction in which electricity is conducted by the copper plates making contact, but over time the contacts can become worn and corroded. If the contacts remain corroded, electricity will not flow even if they are in contact, resulting in poor contact. As a countermeasure, gold, which is more corrosion-resistant than copper, is used in leaf switches that are used under severe conditions.