Inkjet image forming apparatus, method of designing same and method of improving image formation quality

A method of designing an inkjet image forming apparatus including:

• a liquid ejection head having an ejection surface in which a plurality of nozzles are arranged two-dimensionally;
• a scanning device which conveys at least one of the liquid ejection head and an image formation receiving medium on which liquid ejected from the plurality of nozzles is deposited, to cause relative movement between the image formation receiving medium and the liquid ejection head in a first direction;
• and a member which vibrates at a fixed frequency that is independent of a speed of the relative movement caused by the scanning device in such a manner that relative vibration is caused between the image formation receiving medium and the plurality of nozzles,
• wherein when vp represents a relative scanning speed produced by the scanning device in forming an image on the image formation receiving medium by the relative movement and droplet ejection from the liquid ejection head, fv represents the fixed frequency, and OSy represents an offset distance in the first direction of a pair of nozzles which form dots that are mutually adjacent in a second direction perpendicular to the first direction on the image formation receiving medium, of the plurality of nozzles arranged two-dimensionally, then nozzle arrangement in the liquid ejection head, the frequency of vibration of the member, and the relative scanning speed are specified in such a manner that relationship of OSy≈k×vp/fv (where k is a natural number) is satisfied.

A method of improving image formation quality of an inkjet image forming apparatus including:

• a liquid ejection head having an ejection surface in which a plurality of nozzles are arranged two-dimensionally;
• a scanning device which conveys at least one of the liquid ejection head and an image formation receiving medium on which liquid ejected from the plurality of nozzles is deposited, to cause relative movement between the image formation receiving medium and the liquid ejection head in a first direction;
• and a member which vibrates at a fixed frequency that is independent of a speed of the relative movement caused by the scanning device in such a manner that relative vibration is caused between the image formation receiving medium and the plurality of nozzles,
• the method comprising the steps of:
• acquiring information indicating a relative scanning speed produced by the scanning device when forming an image on the image formation receiving medium by the relative movement and droplet ejection from the liquid ejection head;
• acquiring information indicating the fixed frequency of the member;
• acquiring information indicating an offset distance in the first direction of a pair of nozzles which form dots that are mutually adjacent in a second direction perpendicular to the first direction on the image formation receiving medium, of the plurality of nozzles arranged two-dimensionally;
• and
• changing at least one of the relative scanning speed produced by the scanning device and the fixed frequency of the member so as to satisfy relationship OSy≈k×vp/fv (where k is a natural number, vp represents the acquired relative scanning speed, fv represents the acquired fixed frequency, and OSy represents the acquired offset distance).