Patent ID: 7331662

Claim:
An ink cartridge, comprising: an ink containing section including an ink absorbing body made of a porous material for retaining ink, the ink cartridge satisfying: { T·S /( C·D·μ·L·Q )} 0.5 ≧( N·R )≧γ· h /( T·B ) where T is a surface tension of the ink, expressed in Newton per meter, absorbed in the ink absorbing body; S is a cross-sectional area of the ink absorbing body, expressed in square meter, when the ink absorbing body is contained in a compression state in the ink containing section; C is a coefficient of C=1.88×10 5 ; D is a diameter of a nozzle, expressed in meter, through which the ink containing section ejects ink; μ is a viscosity of the ink in Pa·s; L is a height in meter of the ink absorbing body when the ink absorbing body is contained in a compressed state in the ink containing section; Q is a maximum amount of ink, expressed in cubic meter per second, ejected from the nozzle; N is a cell density, expressed in the number of pores per inch, of the ink absorbing body before the ink absorbing body is contained in the ink containing section; R is a compressibility, which is a volume ratio of the ink absorbing body when the ink absorbing body is contained in a compressed state in the ink containing section to the ink absorbing body before the ink absorbing body is contained in the ink containing section; γ is a specific gravity of the ink; and h is a maximum vertical head height, in meter, of the ink containing section relative to an ink supplying throat oriented in an arbitrary position; and B is a coefficient of B=0.0161.