bell button vs doorbell

bell button

noun
  • A small, round mechanical device which, when pressed, rings a bell to announce one's presence or call a servant, assistant, etc. 

  • A button in the form of a jingle bell, used as a fastener or decoration on a piece of clothing. 

doorbell

noun
  • A device on or adjacent to an outer door for announcing one's presence. It can be mechanical, directly sounding a bell, or a button that electrically sounds a chime or buzzer inside the building. 

  • A button that activates an electric doorbell. 

verb
  • To ring many doorbells of (target people or an area) in an effort to contact people and thereby spread information or solicit. 

  • To ring many doorbells in an effort to contact people and thereby spread information or solicit. 

How often have the words bell button and doorbell occurred in a corpus of books? (source: Google Ngram Viewer )