Touch Sensors VS Mechanical Buttons

2019-07-22

Have you ever had a button that gets stuck when you press it?

Or how about one that won’t go down because something has fallen between the air gaps?


While mechanical buttons can be an inexpensive option for your design, they can also sometimes have problems. To solve this, a capacitive touch interface has been incorporated into a vast number of products. However, those can have issues of their own.


In recent years, capacitive touch interfaces have become commonplace on products that have traditionally used mechanical buttons. Products as diverse as remote controls, wall-mounted panels, white goods appliances, and of course smart phones all now routinely use capacitive input surfaces. Despite the popularity of capacitive sensing surfaces, designers should weigh both the advantages and disadvantages of capacitive sensing technology against older mechanical button technology before deciding on the best interface for their products.

 

In many cases, mechanical buttons require less current to monitor than capacitive sensing inputs because mechanical buttons can be tied to port match wake-ups that allow the system to be in an extremely low power state without waking for any monitoring or maintenance. Mechanical buttons are also generally less susceptible to generating false positive touch events due to coupled interference on the MCU’s input pin. This is because mechanical buttons are monitored using digital input pin logic, whereas capacitive sensing solutions require more sensitive analog hardware. Finally, mechanical buttons tend to do a better job of sensing touches from gloved hands, because many fabrics electrically insulate fingers and prevent capacitive sensing solutions from detecting them.


Capacitive sensing inputs became a popular choice for interface design because of the flexibility offered by capacitive sensing input surfaces compared to mechanical inputs. With capacitive sensing inputs, buttons can be shaped in a wide variety of ways, and slider and control wheel designs can be implemented in a way that can be visually attractive while not adding additional manufacturing burden.  A capacitive sensing input surface enables designers to create attractive and distinct products.


Capacitive sensing inputs also mean fewer mechanical parts on a bill of materials relative to a design with mechanical buttons. Many capacitive sensing interfaces consist only of a PCB with electrodes, an acrylic overlay, and a decal adhered to the overlay. This reduced BOM count can lower manufacturing cost and time. Fewer mechanical parts also means lower risk of failure in the field, as capacitive sensing buttons don’t wear out and break like mechanical buttons do.


Mechanical and capacitive solutions both have susceptibility to moisture, however. Mechanical button designs that are not waterproof can be permanently damaged when water slips into the product’s circuitry, often through gaps in the mechanical button components of the interface. Capacitive sensing solutions are often more robust against permanent damage because the acrylic overlays are often a solid acrylic material with no gaps or seams where moisture can enter. However, capacitive sensing solutions can detect false positive touch events due to moisture on the sensing surface without sophisticated firmware-implemented countermeasures.

It is suggested that you should still choose a way (touch sensors or mechanical buttons)that is more suitable for your own products according to the characteristics of the products and the needs of the users.

And welcome to check Reshine’s Capacitive and Resistive touch screen, custom touch is accepted.

smart touch


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