Backup archive until time with curent date auto !

 Hi,

  I use RMAN script to backup archivelogs:

     backup format '/archive/xbank_%t_%s.arcbk' archivelog until time "to_date('2011-11-22:11:30:00','YYYY-MM-DD:hh24:mi:ss')" delete input;

   

  But now, I don't want every backup I must open this script and edit time (ex: 2011-11-22 to 2011-11-23, ...etc...). How I can backup archivelog every day with scheduler from 7h AM to 10h AM every day but not edit current date ?

  Thanks