Junghans is a German watch company, which developed and patented it's own alarm movement J89 Minivox in 1949. Production started in 1951 and ended arround 1958. Junghans produced movements also for Bulova (see Bulova 12-B).
Three versions of J89 exists but with only minor changes between each other. In general J89 is a movement with joint spring barrel for alarm and time. Interesting fact is that Jungans introduced two separated crowns, one for alarm setting and one for alarm On/Off function which protected unpleasent change of alarm time while turning on/off the alarm (common complain to AS1475 for example).
Central crown in position 0: Winding time and alarm.
Central crown in position 1: Setting the time.
Upper crown: Setting alarm (only anti clockwise).
Lower crown: Alarm on (position 0)/ alarm off (position 1). Some versions have vice versa, stated is how my version works.