Developing apparatus and image forming apparatus

A method for controlling an image forming apparatus, including a development unit configured to supply toner to a photoconductor on which an electrostatic image is formed, a supply unit configured to supply toner to the development unit, and a sensor configured to detect a concentration of toner in the development unit, the method comprising:

• controlling the supply unit to perform a toner supply process, when the detected concentration of the toner is lower than a first value;
• controlling the sensor to detect the concentration of the toner after the toner supply process;
• counting the number of times the sensor detects the concentration of the toner to be higher than a second value that is higher than the first value;
• and
• controlling the supply unit to repeat the toner supply process, when the counted number is less than a predetermined number that is equal to or greater than two.

An image forming apparatus, comprising:

• a photoconductor configured to carry an electrostatic image;
• a development unit configured to supply toner to the photoconductor;
• a transfer unit configured to transfer the toner on the photoconductor to a medium;
• a supply unit configured to supply toner to the development unit;
• a sensor configured to detect a concentration of toner in the development unit;
• and
• a control unit configured to, in response to the detected concentration of the toner being lower than a first value:
• control the supply unit to perform a toner supply process,
• control the sensor to detect the concentration of the toner after the toner supply process,
• count the number of times the sensor detects that the concentration of the toner to be higher than a second value that is higher than the first value, and
• control the supply unit to repeat the toner supply process, when the counted number is less than a predetermined number that is equal to or greater than two.