# Difference between a normal tactile switch/pushbutton and a detection switch/pushbutton

What is the general difference between a normal tactile switch/push button and a detection switch/push button?

I have heard that if in an application, for example, a pushbutton has to be pressed for a long time (several years) until it is used, detection switches/pushbuttons are guaranteed to still work whereas this is not granted with tactile pushbuttons. Is this true?

I'm asking about an application in medical technology, but also just general knowledge, as I can't seem to find any information about it!

• I have heard... please provide a link to your source information. Feb 8 at 13:40
• There is no link to the source, it is mouth-to-mouth propaganda from colleagues. this is why I wrote I heard and mentioned that I didn't find any information about it. Feb 8 at 14:42
• Then link to examples of the two types of switch. Feb 8 at 14:43
• All switches tend to have an electrical life and a mechanical life specified. You need to pick one that matches the expected life time of the product. Tact switches are mostly suitable for entering calibration modes etc that's only used a few times. They aren't something you should design in when designing (high quality) user interfaces. Feb 8 at 15:15
• @Lundin tact switches are used literally everywhere as device UI buttons. They are just hidden behind a custom device specific hats maybe for look and feel. They can also have a life of hundreds of thousands to millions of cycles, so not limited to rare events. Feb 8 at 22:06

The difference is the tactile feedback or the lack of it, i.e. what is the intended usage of the switch.

Tactile switches are meant to be directly operated by humans, so they are used as user interface buttons, they have definite operating force and they give touch feedback to user of the operation, maybe even a definite click sound.

Detection switches are not directly meant to be operated by humans so they don't need to have a definitive feel or withstand human force. Detection switches are used to detect for example if a door or laptop lid is closed or open.

At least one industrial switch maker has rated tact switches to have much more cycles of operating life than detect switches. So even if it is a medical device you select a suitable switch for suitable thing, if it is for UI or something else, as long as switch is rated for such thing in medical context.

Regular switches are designed for humans, meaning everything is tailored for the human user's experience. Usually having those 'tactile' bumps to let humans know the click is registered and such.

Detector switches are designed for mechanical movements, so usually has no tactile bumps being completely linear. Actuation forces will generally be quite low, as they're purely for detection, not to intervene with mechanical movements. And as you said, will always be guaranteed to work after being static for longer amounts of time.

Sometimes the lines between different switches can be quite vague, but if you understand the intent of those designs, it becomes easier.

Here's an example of a 'detection' switch.

It's a momentary push button switch with a 'normally closed' contact, that is kept open for an extended period by the glass pressing against it.

In the case of an emergency / fire, breaking the glass, with the hammer that's been provided, releases the push button. The resulting contact closure sets off the alarm.

• More likely the contact is held closed so that loop break will trigger the alarm. Feb 8 at 17:50
• Thank you, @Transistor. You're right, both 'NO' and 'NC' contacts would be available for fail-safe operation. Feb 9 at 3:05