Connecting People and Products – The User Interface Part IV : Keys and Controls

19 Mar


Part IV (Final) : Keys and Controls

Crux of it…

Thoughts on keys, controls and related designs.


Displays and indicators provide vital information on a process or application. Most applications demand user intervention often. If the display screen real estate is limited, then several screen pages are required to display volume of data  and different parameters. There needs to be a way to intervene as and when needed or when required to view different screens and set process parameters.Keys and controls play vital role in user interaction.

Let us discuss the key points to be considered while designing keypads and providing for controls.





Normal human psychology would be to look toadjacent displays for any of their actions.

Keys and controls related to a display must be grouped and placed adjacent to the same. This also helps the user to access the right keys even during emergencies.




When we change TV channels through remote, we need instant response. While running on the treadmill, we require the speed to change as quickly as possible and comfortable , as soon as we press the key. A key press if not responded by the system within about 200 msecs, the user becomes aware of the same and experiences discomfort on continuous usage.

Immediate feedback such as a clicking beep would instantly make the user understand that his key action has been recognized by the system. For a rotary control, the clicking noise of engagement automatically informs the user that the control has moved to the next position.


Suitable Precision

                                                                                                                                  Low Precision

Low Precision

Precision of adjustment for a control must be suitable for the application. When we use a normal table fan, it may be sufficient to have a control which has only four positions – OFF, LOW, MEDIUM AND HIGH. Fan does not require a control which sets RPM from 0 to 1000.

                                  High Precision


High Precision


A hair dryer can have only three control settings – OFF, LOW, HIGH, whereas a refrigerating system used in a clinical laboratory may need settings in Centigrades starting from -50 Degrees.

Providing a high precision control for a lower application requirement can be inconvenient while vice-versa can be catastrophic.





Identification & Shapes



Clear labeling of the controls and keys will prevent improper operation. Keys used for incrementing and decrementing can be triangular in shape. Buttons used in emergency situations can be of larger sizes and of colors that easily stand out.

Embossing of key pads will provide the tactile satisfaction to the user and gives a nice operating experience.



User Interface has grown leaps and bounds with touch screens and high resolution graphic displays. New operating systems like Android facilitate easy and seamless interface making the user experience unforgettable.


I have chronicled my thoughts so far in these four parts in the sincere hope that it could prove useful to those who need it.



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