My cell phone when its keypad is locked (so that it ignores keypresses) displays a small picture of a key on the display. I find it rather confusing - IMO it should be a picture of a padlock which is just the same recognizable but indicates that the phone is "under lock", not "somehow related to a key".

I'd like to know why using a picture of a key could be advantageous in this scenario.

Why would one prefer using a picture of a key over a picture of a padlock to indicate that a device is locked?

7 Answers 7


You say a small picture of a key. It's a lot easier to depict a recognisable key than padlock at small sizes.

I'm guessing the icon may well appear in a notification area where either the vertical dimension or number of colours is particularly limited - many notification icons are one colour or greyscale/monochrome.

From experience, you can draw a recognisable key that's only 3 pixels high in black pixels only, a padlock needs to be at least 5 or 6 pixels high and isn't very recognisable at that size unless you add another colour or tone.


Sounds like just a bad design. Key = Un/lock action. Padlock = Un/locked state.


The only situations I can imagine where a key would be better are:

  • Where the application uses keys to signify 'locked' everywhere else (in which case, it'd probably be wiser to stick to convention than alter the entire interface
  • Where unlocking requires a password or pincode, and key icons signify sign-in points throughout the rest of the application
  • Where padlocks are used elsewhere to signify something else (like un-editable data), and testing confirms that users get confused

I thought mine used a lock (which would be more logical)- but despite having had it for several years I find it (a Nokia) also uses a key.

Displaying a Keys or a Lock indicates the locked state. Displaying nothing indicates the unlocked state. So it doesn't really matter.


Android, for example, uses the padlock instead of a key. I know in the past, usually in feature phones it was a key. But they would also word it differently. My Sony Ericssion feature phone used to say, "To unlock, press this key" and then have an image of a key there.


I'm guessing a key is easier to paint as an icon than a lock. That would be a good reason for the key icon being more popular.

The key indicates the action and the lock indicates the state, so no harm done.


The use of 'key' icon on a key-press symbolizes that you require a 'key' (metaphorically used) to unlock the device and a mere pressing of buttons wouldn't suffice. The 'key' here being a particular keypad combination or a physical button.

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