Printing apparatus, discharge state detecting apparatus, and discharge state detecting method

A discharge state detecting apparatus for detecting a discharge state of a liquid droplet discharged from a head having a discharge surface in which a nozzle configured to discharge a liquid droplet in a first direction is opened, the discharge state detecting apparatus comprising;

• a light-emitter configured to emit light;
• a light-receiver configured to receive the light emitted from the light-emitter;
• a gradient adding member configured to add a gradient to a light intensity of an optical path of the light emitted from the light-emitter in each of a second direction and a third direction, the second direction and the third direction intersecting the first direction, the second direction and the third direction intersecting with each other;
• and
• a controller configured to detect a deviation of a flying direction of the liquid droplet discharged from the nozzle based on an amount of the light received by the light-receiver in a case that the liquid droplet discharged from the nozzle travels through the optical path at a position between the gradient adding member and the light-receiver.

A discharge state detecting method for detecting a discharge state of a liquid droplet in a printing apparatus:

• the printing apparatus including:
• a head having a discharge surface in which a nozzle configured to discharge a liquid droplet in a first direction is opened;
• a light-emitter configured to emit light;
• a light-receiver configured to receive the light emitted from the light-emitter;
• a gradient adding member;
• and
• a controller,
• the method comprising:
• adding a gradient to a light intensity of an optical path of the light emitted from the light-emitter in each of a second direction and a third direction by the gradient adding member, the second direction and the third direction intersecting the first direction, the second direction and the third direction intersecting with each other;
• causing the nozzle to discharge the liquid droplet, by the controller, so that the liquid droplet travels through the optical path to which the gradient is added;
• and
• detecting, by the controller, a deviation of a flying direction of the liquid droplet discharged from the nozzle based on an amount of the light received by the light-receiver in a case that the liquid droplet travels through the optical path.