Patent ID: 7600472

Claim:
A pump control mechanism comprising: a pump unit that feeds liquid stored in a liquid supply source to a container and has: a pump member; and a motor that drives the pump member and is controlled based on control information; and an information memory that stores: a control table having a plurality of the control information; and target information corresponding to a target driving speed of the motor when the motor is driven, wherein the control table includes time zone sections corresponding to one driving cycle of the pump member, each of the time zone sections having the control information for increasing or decreasing a driving force of the motor in accordance with a magnitude of a load of the motor, wherein the time zone sections include a control information increasing section for locally increasing the driving force and a control information reducing section for locally reducing the driving force, wherein the control table contains an area where the control information increasing section and the control information reducing section are alternately repeated, wherein an average of the control information in the area is set to be larger than the control information required to drive the motor in the area, wherein the control information is a duty ratio for carrying out PWM control at a pulse voltage applied to the motor, wherein the duty ratio of the last section in the time zone sections corresponding to one driving cycle of the pump member is set to the control information increasing section, and wherein the duty ratio of the last section is higher than the duty ratio of the initial section in the time zone sections and is lower than an average of the duty ratio in the time zone sections.