Apparatus and method for measuring droplet information, and inkjet printing system

A method for measuring droplet information of a droplet information measuring device, comprising:

• illuminating a droplet ejected onto a surface of a substrate from an inkjet printing device with first light and second light simultaneously or sequentially;
• photographing, by a camera, the droplet being illuminated by at least one of the first light and the second light from above the droplet;
• and
• analyzing at least one image photographed by the camera to acquire droplet information related to the droplet,
• wherein the first light has a first optical characteristic and is emitted in an oblique direction with respect to the surface of the substrate, and
• wherein the second light has a second optical characteristic different from the first optical characteristic and is emitted in a direction perpendicular to the surface of the substrate.

An inkjet printing system, comprising:

• an inkjet printing device;
• and
• a droplet information measuring device configured to measure droplet information of a droplet ejected onto a substrate by the inkjet printing device,
• wherein the droplet information measuring device comprises:
• a first light source module configured to emit a first light having a first optical characteristic, the first light being emitted from the first light source module in an oblique direction with respect to a surface of a substrate on which the droplet is positioned;
• a second light source module configured to emit a second light having a second optical characteristic that is different from the first optical characteristic, the second light being emitted from the second light source module in a direction perpendicular to the surface of the substrate;
• a camera configured to photograph the droplet being illuminated with at least one of the first light and the second light from above the droplet;
• and
• a control module configured to analyze at least one image photographed by the camera to acquire droplet information therefrom.