Printing liquid supply device, printing liquid circulation device and printing machine

A printing liquid supply device comprising:

• a pump that is interposed in a supply path of a printing liquid and pumps the printing liquid;
• and
• a viscosity measurement device interposed in the supply path to measure viscosity of the printing liquid,
• wherein the viscosity measurement device includes
• a passage part having a first passage portion in which a flow path cross-sectional area for the printing liquid is set to a first area, and a second passage portion which is disposed upstream of the first passage portion in a supply direction of the printing liquid and in which the flow path cross-sectional area for the printing liquid is set to a second area smaller than the first area, the passage part being interposed in the supply path and disposed on an upper side toward a downstream side in the supply direction of the printing liquid,
• a measurement tool which is pushed up by the printing liquid when supply of the printing liquid is performed, and falls in the printing liquid when the supply of the printing liquid is stopped, and
• a measurement part which is mounted to the second passage portion and measures the viscosity of the printing liquid, based on a time for which the measurement tool falls in a predetermined vertical area in the second passage portion, and
• wherein the first passage portion is provided with an enlarged diameter passage portion whose flow path cross-sectional area continuously increases from the second passage portion toward the downstream side in the supply direction of the printing liquid.