Abstract: A device for detecting a state of a liquid droplet discharged from each of nozzles placed in one or more rows, includes a light emitting element to emit a light beam to the liquid droplet from a nozzle in question, and a pair of light receiving elements disposed on both sides of a beam diameter of the light beam via an optical axis to receive scattered light occurring from the liquid droplet for detecting a state of the discharged liquid droplet on the basis of the scattered light. Either of the pair of the light receiving elements is selected for receiving the scattered light from the liquid droplet discharged from the nozzle according to a positional relation between the nozzle and the pair of light receiving elements.

Abstract: A device for detecting a state of a liquid droplet discharged from each of nozzles placed in one or more rows, includes a light emitting element to emit a light beam to the liquid droplet from a nozzle in question, and a pair of light receiving elements disposed on both sides of a beam diameter of the light beam via an optical axis to receive scattered light occurring from the liquid droplet for detecting a state of the discharged liquid droplet on the basis of the scattered light. Either of the pair of the light receiving elements is selected for receiving the scattered light from the liquid droplet discharged from the nozzle according to a positional relation between the nozzle and the pair of light receiving elements.

Abstract: An image forming system including a first image forming apparatus and a second image forming apparatus. The first image forming apparatus forms an image on a first side of a recording medium and has a mark forming device to form a mark on the recording medium. The second image forming apparatus forms an image on a second side which is the obverse of the first side, and has a mark detector to detect the mark at a predetermined position in a conveyance path of the recording medium and a calculator to calculate an expansion and contraction ratio of the recording medium in a first direction and in a second direction perpendicular to the first direction based on the output of the mark detector.

Abstract: An image forming system including a first image forming apparatus and a second image forming apparatus. The first image forming apparatus forms an image on a first side of a recording medium and has a mark forming device to form a mark on the recording medium. The second image forming apparatus forms an image on a second side which is the obverse of the first side, and has a mark detector to detect the mark at a predetermined position in a conveyance path of the recording medium and a calculator to calculate an expansion and contraction ratio of the recording medium in a first direction and in a second direction perpendicular to the first direction based on the output of the mark detector.