Image forming apparatus

An image forming apparatus comprising:

• a recording head including a nozzle that jets liquid droplets;
• a liquid tank that retains liquid to be supplied to the recording head;
• a first flow path through which the liquid is supplied to the recording head;
• a second flow path connected to the liquid tank;
• a pressure adjustment valve connecting the first flow path with the second flow path, wherein a flow path resistance inside the pressure adjustment valve changes in accordance with a flow rate of the liquid flowing through the first flow path;
• a third flow path connecting the second flow path or the liquid tank with the pressure adjustment valve;
• a liquid sending unit that performs a liquid sending operation, the liquid sending unit being provided in the third flow path;
• a fourth flow path that connects the recording head with the liquid tank and bypasses the pressure adjustment valve;
• a flow path opening/closing valve that performs an opening/closing operation for opening and closing the fourth flow path;
• a liquid jetting amount detecting unit that detects a liquid jetting amount of the liquid droplets jetted from the recording head;
• and
• a control unit that controls the opening/closing operation performed by the flow path opening/closing valve and the liquid sending operation performed by the liquid sending unit, wherein
• the control unit controls the liquid sending unit to perform the liquid sending operation and controls the flow path opening/closing valve to close the fourth flow path when the liquid jetting amount detected by the liquid jetting amount detecting unit is greater than or equal to a predetermined amount that is determined in advance, and controls the liquid sending unit to stop the liquid sending operation and controls the flow path opening/closing valve to open the fourth flow path when the liquid jetting amount detected by the liquid jetting amount detecting unit is less than the predetermined amount, and
• the recording head is located at a higher position than that of the liquid tank, and the liquid flows to the recording head from the liquid tank via the pressure adjustment valve when the liquid droplets are jetted from the recording head.

An image forming apparatus comprising:

• a recording head including a nozzle that jets liquid droplets;
• a liquid tank that retains liquid to be supplied to the recording head;
• a first flow path through which the liquid is supplied to the recording head;
• a second flow path connected to the liquid tank;
• a pressure adjustment valve connecting the first flow path with the second flow path, wherein a flow path resistance inside the pressure adjustment valve changes in accordance with a flow rate of the liquid flowing through the first flow path;
• a third flow path connecting the second flow path or the liquid tank with the pressure adjustment valve;
• a liquid sending unit that performs a liquid sending operation, the liquid sending unit being provided in the third flow path;
• a fourth flow path that connects the recording head with the liquid tank and bypasses the pressure adjustment valve;
• a flow path opening/closing valve that performs an opening/closing operation for opening and closing the fourth flow path;
• a position detecting unit that detects a position of a movable member accommodated inside the pressure adjustment valve in such a manner as to move freely;
• and
• a control unit that controls the opening/closing operation performed by the flow path opening/closing valve and the liquid sending operation performed by the liquid sending unit, wherein
• the control unit controls the liquid sending unit to perform the liquid sending operation and controls the flow path opening/closing valve to close the fourth flow path when the position of the movable member detected by the position detecting unit is closer to the first flow path than a predetermined position that is determined in advance, and controls the liquid sending unit to stop the liquid sending operation and controls the flow path opening/closing valve to open the fourth flow path when the position of the movable member detected by the position detecting unit is closer to the second flow path than is the predetermined position, and
• the recording head is located at a higher position than that of the liquid tank, and the liquid flows to the recording head from the liquid tank via the pressure adjustment valve when the liquid droplets are jetted from the recording head.