Superboy #104

Jor-El invents the Phantom Zone Projector as a more humane way to punish criminals than sending them into space and successfully submits it into a Science Council competition. The disgruntled loser of the competition, Gra-Mo, takes over Krypton's robots to take his revenge, and ironically becomes the last criminal to be punished in the old way. Months later, after many convicts have been sent into the Phantom Zone, the prisoners try to take over Jor-El's mind with mental telepathy, so he blasts the Zone Projector into space with other forbidden weapons.