What Is a Switchhook?
Switchhooks, also called hook switches, are switches that are turned on and off by hanging an object on a hook.
They are mainly used for the switch located on the part of a landline telephone where the handset is placed. The name comes from the fact that the handset was hung on the hook of the main unit. The action of pressing the switchhook and speaking immediately during a call is called hooking, and is sometimes used to switch between on hold and talking, etc.
In recent years, cordless and mobile phones have become popular, eliminating the need to hook the handset on anything and reducing the number of products in use.
Usage of Switchhooks
Mainly used in fixed-line telephones. For public telephones and landline telephones used in offices and homes that have a corded handset, switchhooks are used because the call can be disconnected by placing the handset on the hook.
In recent years, cordless phones, such as cell phones and smartphones, have become widespread. Since cordless calls are switched on and off using buttons and other means, switchhooks are not used. As a result, the number of products in use is decreasing.
Principle of Switchhooks
Switchhooks have two states: on-hook when the telephone receiver is placed on the telephone, and off-hook when the receiver is lifted.
In the on-hook state, the switchhook is depressed by the handset and the contacts are released. In the off-hook state, the switchhook is released and the contacts are electrically connected.
The operating principle of the switchhook is that the weight of the handset presses the hook button, causing the button to rotate around its axis, which in turn rotates the internal switch lever and connects the contacts.
There is no electrical control of the switch. When a person hangs up, the motion of placing the handset down is used as an input, and electrical continuity is established by mechanical action. When a person picks up the receiver to make a call, the mechanical action is used as input to ensure electrical non-conduction of the switch.