Ink droplet expelling apparatus

An apparatus for expelling ink droplets in accordance with electric signals comprising:

• a printing head having two ink chambers and at least one nozzle for expelling ink, said chambers being disposed serially in the ink expelling direction and communicated with each other through an orifice;
• ink supply means communicated with at least one of said ink chambers for supplying said at least one of said ink chambers with ink,
• electric signal generating means for generating a first, a second and a third signal;
• and
• pressure generating means including a first and a second pressure generator arranged serially in the ink expelling direction for varying said ink chambers in volume, said first pressure generator being arranged to make high pressure in one of said ink chambers in response to said first signal and also to make another high pressure in said one ink chamber in response to said third signal to suppress pressure fluctuation in said one chamber caused by said first and second pressure generators, said second pressure generator being disposed closer to said nozzle than said first pressure generator and arranged to make high the pressure in another of said ink chambers in response to said second signal so as to cause said another chamber to expel an ink droplet out of said nozzle, said first signal being applied first to said first pressure generator, said second signal being applied to said second pressure generator with a predetermined time delay from said first signal, said third signal being applied to said first pressure generator with a predetermined time delay from said second signal.

An apparatus for expelling ink droplets in accordance with electric signals comprising:

• a printing head having a plurality of ink expelling nozzles, a common ink chamber and a plurality of ink chambers correspondingly respectively communicated with said ink expelling nozzles;
• ink supply means communicated with at least said common ink chamber for supplying at least said common ink chamber with ink;
• electric signal generating means for generating a first, a second, and a third signal;
• and
• pressure generating means including a plurality of individual pressure generators provided on said head respectively corresponding to said ink chambers, each of said ink chambers being communicated with said common ink chamber through an orifice and a common pressure generator provided on said head corresponding to said common ink chamber;
• said common pressure generator being arranged to make high pressure in said common ink chamber in response to said first signal and also to make another high pressure in said common ink chamber in response to said third signal to suppress pressure fluctuation in said ink chamber caused by said common an individual pressure generators, and
• each of said individual pressure generators being disposed closer to said nozzles than said common pressure generator and arranged to make high the pressure ins aid associated ink chambers in response to said second signal so as to cause said chambers to expel an ink droplet out of said nozzles, said first signal being applied first to said common pressure generator, said second signal being applied to a designated one of said individual pressure generators with a predetermined time delay from said first signal, and said third signal being applied to said common pressure generator with a predetermined time delay from said second signal.