Ink supply system with tube pump

An ink supply system for a writing instrument which operates with liquid ink;

• said system comprising:
• a housing for said writing instrument, said housing including a primary large-volume reservoir for ink, and a secondary, small-volume reservoir;
• a writing element connected to said housing;
• said secondary reservoir communicates with outside air and with said writing element;
• a tube pump which acts as a recharge valve, is controllable as a function of need, and connects said large-volume reservoir to said small-volume reservoir;
• which includes, as a drive mechanism for said tube pump, an electric motor in said housing;
• and which includes a battery in said housing for said electric motor;
• which includes a sensor associated with said secondary reservoir for monitoring the content thereof, and for controlling said drive mechanism for effecting said control of said tube pump;
• said large-volume reservoir being in the form of a replaceable ink cartridge;
• said housing including a seat for said cartridge, and associated with said seat, a spring contact arrangement for disconnecting said battery from said drive mechanism when no ink cartridge is provided on said seat;
• said ink cartridge being essentially at atmospheric pressure, and the pressure necessary to convey ink from said cartridge to said secondary reservoir is produced by said tube pump;
• said tube pump being a peristaltically-operating tube pump having a tube which essentially extends in the axial direction of said housing;
• said tube pump being provided with at least three successively connected chambers, each of which includes a radially moved piston, and has a portion of said tube disposed therein;
• said pistons successively and periodically squeeze together said portions of said tube.