Image forming apparatus and image forming system

An image forming system, comprising:

• an image forming apparatus;
• and
• a toner container;
• wherein the image forming apparatus comprises:
• a printing device to which a toner container is mounted, and configured to perform printing using toner in the toner container;
• an ultrasonic sensor arranged so as to correspond to a mounting position of the toner container, and configured to (a) output an ultrasonic wave to a specific position of the toner container, (b) detect the ultrasonic wave that passes through the toner container, and (c) output a detection signal corresponding to an intensity of the detected ultrasonic wave;
• and
• a controller configured to determine whether the toner container is a genuine product or not on the basis of a level of the detection signal of the ultrasonic sensor when the toner container is mounted;
• wherein a housing of the toner container has at a specific position a thickness corresponding to production timing of the toner container;
• the ultrasonic sensor outputs the detection signal of a level corresponding to the thickness;
• and
• the controller (a) determines that the toner container is a genuine product if a level of the detection signal of the ultrasonic sensor is a level corresponding to a time point within a production term of the toner container;
• and (b) determines that the toner container is not a genuine product if a level of the detection signal of the ultrasonic sensor is not a level corresponding to any time point within a production term of the toner container.