Ribbon cartridge for printing machines

A ribbon cartridge for a typewriter or other printing machine of the type comprising rotatable feed means and a control lever, and in which the cartridge comprises a casing having a bottom portion, a front wall, a rear wall, two side walls and a cover portion;

• a typing ribbon carried by said casing and having an operative portion stretched outside said casing;
• a feed spool winding a non-used typing ribbon;
• a take-up spool on which the typing ribbon is rewound after the typing ribbon has been used, wherein said feed spool comprises a core tube, on which one end of the typing ribbon is fixed, and a flange which is fixed to the bottom of the core tube, and wherein said take-up spool comprises a core tube;
• means for causing said rotatable feed means to drive the take-up spool for winding the typing ribbon thereon;
• and wherein the bottom portion and the cover portion of said casing comprise support means for supporting and guiding the feed spool and the take-up spool in the casing adjacent to one of said side walls and another of said side walls, respectively;
• and tensioning and signalling means for causing the operative portion of said typing ribbon to be held tensioned without slackening and for enabling said control lever to cooperate with an internal portion of the typing ribbon unwinding from said feed spool, said tensioning and signalling means defining a combination comprising:
• a first aperture in the bottom portion having the form of a circular sector disposed adjacent to the core tube of the take-up spool and configured to house the rotatable feed means in order to cause said rotatable feed means to engage the typing ribbon which is wound on the take-up spool and to rewind the typing ribbon on said take-up spool for unidirectional feeding of the typing ribbon;
• a resilient blade which is integral with both the rear wall and the bottom portion of said casing adjacent to said feed spool, wherein the flange of said feed spool is provided on its outside edge with a series of peripheral notches and wherein said resilient blade cooperates with the series of peripheral notches to prevent casual rotation of the feed spool and thus uncontrolled unwinding of the typing ribbon;
• a seat in the bottom portion positioned adjacent to but spaced from the first aperture having a predetermined form for housing the core tube of the take-up spool;
• a resilient tongue which is integral with the bottom portion of said casing, is provided with a pawl member and is housed with said pawl member in the seat, wherein the core tube of said take-up spool is provided with a series of saw teeth positioned in the seat and coplanar with the pawl member of the resilient tongue, and wherein the pawl member of said resilient tongue cooperates with the series of saw teeth of the core tube of the take-up spool for enabling the rotary movement of said core tube in the direction of winding of the typing ribbon but preventing the rotary movement of said core tube in the other direction, even when the cartridge is removed from the typewriter;
• guide elements disposed adjacent to the front wall of said casing and to the flange of said feed spool for guiding said internal portion of the typing ribbon internally to the casing;
• said guide elements comprising a first guide element adjacent to said one side wall and a second guide element adjacent to said flange, wherein said internal portion of the typing ribbon comprises a first postion directed frontwardly toward said front wall, a second portion between said first and said second guide elements, and a third portion directed rearwardly from said second element toward the rear wall;
• and
• means defining a second aperture in the bottom portion of said casing disposed between the guide elements in front of said internal portion of the typing ribbon;
• wherein said second aperture is configured to house said control lever in order to cause said control lever to control the unwinding of the typing ribbon from the feed spool and to cause the second portion of said internal portion of the typing ribbon to form a V-shaped loop in the typing ribbon between the guide elements during the normal rewinding of the typing ribbon, and to signal complete unwinding of the typing ribbon from the feed spool when the tension in said typing ribbon eliminates the V-shaped loop formed in the second portion of said internal portion.