What type of button is this on a remote control
The remote control of my TV has two kinds of buttons. There are "normal" ones for the digits etc. which work by bringing a conductive material on the underside of the button in contact with the board of the remote control to establish contact.
And then there are these round silver buttons in the centre for the remote. One pushes their curved surface down to bring it into contact with, presumably, a contact below (not visible from the outside).
How is this later type of button called? I don't need a specific part name or number, just a general category name would be helpful.
2 answers
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| User | Comment | Date |
|---|---|---|
| samcarter | (no comment) | Feb 3, 2024 at 14:45 |
Such a domed button is usually called a "membrane switch", at least here in the US. As you say, the small metal bubble makes contact with something underneath when pressed.
Advantages of membrane switches over the capacitive or conductive sense switches in the rest of your remote include better environmental immunity, a positive click feel, and they can be pushed directly by the user (no additional button required).
A Membrane switch is also usually more convenient electrically. It is a true switch, in that there is a contact that is either closed or open. A capacitive sense switch requires active circuitry to sense, although that's cheaply available in custom ICs for that purpose, and many microcontrollers nowadays.
The downside of membrane switches over the other buttons in your unit is that they are more costly to manufacture.
It's a bit strange that there are two types of switches in the same unit. People don't usually expect a positive feel from TV remote buttons, and any dirt immunity is negated by the other buttons not having it. Maybe this unit was cobbled together from existing parts to get it out quickly.
It is interesting to see how they deposited these carbon electrodes over solder mask and copper traces both under the button foil switches and membrane switches alike which offer more tactile feel. Both offer capacitance changes to non-conductive switches. The membrane switches are mounted on their own clear insulator laminate.
All sensors are configured in a matrix for typical scanning mode typically by a single IC interfaced to a low-budget uC.
The advantage of capacitance switches are better reliability and silent operation except for the sealed membranes which give better tactile feel. Using an audio range signal the sensor IC easily detect the reflection of signals when the gap is reduced < 1mm with programmable sensitivity.
How they chose the need for tactile membranes over the printed fingers must have been based on the frequency of fast operations to reduce false negative operations with the benefit of tactile response.
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