Image forming apparatus including recording head for ejecting liquid droplets

A method for controlling an image forming apparatus comprising a sub tank to store liquid to be supplied to a recording head, a carriage mounting the recording head and the sub tank, a main tank to store the liquid to be supplied to the sub tank, a liquid feed device to supply the liquid from the main tank to the sub tank, and a displacement member provided at the sub tank and displaceable with a remaining amount of the liquid in the sub tank, the method comprising:

• detecting, by a first detector mounted on the carriage, a first position of the displacement member;
• detecting, by a second detector mounted on the apparatus body, a second position of the displacement member;
• detecting and retaining, by a detection retainer, a differential supply amount corresponding to a first displacement amount of the displacement member between the first position and the second position or a second displacement amount obtained by subtracting a predetermined displacement amount from the first displacement amount;
• providing a liquid consumption amount measuring device to receive a detection output of the first detector and measure a consumption amount of the liquid in the sub tank when the displacement member displaces from the first position in a direction in which the consumption amount of the liquid in the sub tank decreases;
• starting, by a supply controller, supply of the liquid from the main tank to the sub tank without using the second detector, when the consumption amount of the liquid measured by the liquid consumption amount measuring device reaches a predetermined threshold value, and supplying the liquid by the differential supply amount after the first detector detects the displacement member;
• and
• controlling by the supply controller, when the first position of the displacement member is detected with the first detector, and the remaining amount of the liquid in the sub tank is smaller than when the second position of the displacement member is detected with the second detector, the liquid consumption amount measuring device to start measuring the consumption amount of the liquid in the sub tank, after detection output of the first detector continues to be, for a first predetermined time, in a detection state in which the first detector detects the displacement member, and then shifts from the detection state to a non detection state in which the first detector does not detect the displacement member.

A method for controlling an image forming apparatus comprising a head tank to store liquid to be supplied to a recording head, a carriage mounting the recording head and the head tank, a main tank to store the liquid to be supplied to the head tank, a liquid feed device to supply the liquid from the main tank to the head tank, and a displacement member provided at the head tank and displaceable with a remaining amount of the liquid in the head tank, the method comprising:

• detecting, by a first detector mounted on the carriage, a first position of the displacement member;
• and
• detecting, by a second detector mounted on the apparatus body, a second position of the displacement member;
• providing a supply controller (i) to control driving of the liquid feed device to supply the liquid from the main tank to the head tank, and (ii) to detect and retain a differential supply amount corresponding to a displacement amount of the displacement member between the first position and the second position,
• wherein when the first position of the displacement member is detected with the first detector, the remaining amount of the liquid in the head tank is smaller than when the second position of the displacement member is detected with the second detector;
• measuring, by the supply controller, a consumption amount of the liquid in the head tank, when the liquid is supplied from the main tank to the head tank without using the second detector during printing operation, and starting, by the supply controller, supplying the liquid from the main tank to the head tank, when the consumption amount of the liquid reaches a predetermined threshold value at which a remaining amount of the liquid stored in the head tank is smaller than when the first detector detects the displacement member;
• controlling, by the supply controller after the first detector detects the displacement member, the liquid feed device to supply the liquid by the differential supply amount from the main tank to the head tank;
• starting, by the supply controller when the differential supply amount is less than a predetermined value, measuring the consumption amount of the liquid in the head tank at end of supplying the liquid by the differential supply amount;
• and
• starting, by the supply controller when the differential supply amount is not less than the predetermined value, measuring the consumption amount of the liquid in the head tank after supplying of the liquid by the differential supply amount ends and a detection output of the first detector shifts from a detection state in which the first detector detects the displacement member to a non detection state in which the first detector does not detect the displacement member.