Mongodb is not case sensitive

  mongodb, question

To implement a mongodb case-insensitive query, for example, the query field is key and the value of key is Rundown.
Now the way to realize the query key can match Rundown ,rundown, but it will not match Rundown1.
May I ask how this can be achieved?
Ps: I used mongdb’s java driver development.

With regular, such as:

db.xxx.find( { key: /^rundown$/i } );