Bar code printing device

A printing device comprising:

• a machine frame;
• a printing head supported by said frame and movable with respect to said frame from a rest position to a printing head printing position for printing a set of selected symbols on a label;
• said printing head further comprising:
• a plurality of type rings for printing said selected symbols;
• each said type ring being generally circular in shape and having a plurality of type heads formed thereon corresponding to respective ones of predetermined said symbols;
• said type rings having a selecting position in which they are spaced relatively far apart and can be rotated independently of each other for selecting said selected symbols;
• said type rings having a type ring printing position in which they are disposed relatively close together for printing;
• a stopper member supported on said printing head and having a protruding position in which it engages said machine frame to prevent said printing head from being moved to said printing head printing position;
• said stopper member having a retracted position in which it does not engage said machine frame and does not prevent said printing head from being moved into said printing head printing position;
• said stoppr member having a projecting cam follower formed thereon;
• a cam member having a cam surface against which said projecting cam follower is biased, said cam member being generally circular in shape and having a diameter approximately equal to or less than the diameter of said type rings and being coaxial with said type rings;
• said cam member being rotatable between first and second cam positions, wherein said first cam position corresponds to said selecting position of said type ring and to said protruding position of said stopper means, and said second cam position corresponds to said type ring printing position and to said retracted position of said stopper means;
• said cam member having a first groove formed in said cam surface which receives said cam follower when said cam member is in said second cam position, said stopper member being in said retracted position when said cam follower is received in said first groove;
• said cam member also having a second groove formed in said cam surface which is shallower than said first groove and which receives said cam follower when said cam member is in said first cam position, said stopper member being in said protruding position when said cam follower is received in said second groove;
• moving means for moving said type rings between said selecting position and said type ring printing position;
• said cam member cooperating with said moving means to move said stopper member from said protruding position to said retracted positon when said moving means moves said type rings to said type ring printing position.