Here's a way to convert the string to uppercase:
Set the field rawValue to a variable, then perform .toUpperCase() and set to new variable.
For example,
var myVar = TextField1.rawValue;
var myNextVar = myVar.toUpperCase();
//Then, if you want to change the rawValue to reflect the upper case
TextField1.rawValue = myNextVar;
You can put this in the exit event, or do it as part of a submit, or what have you.
Lynne