Mimaki Granted U.S. Patent for Inkjet Printer Ink Supply System

U.S. patent No. 8,506,060 has been issued to Mimaki Engineering Co., Ltd, of Japan for a novel ink supply system. The device solves the inner pressure problem in inkjet print heads.

It is said the inner pressure of a print head builds up as ink is forced out of the ink jet nozzles in a stream directed at the print medium. That pressure may cause a dripping problem. The Mimaki patented ink supply device includes a sub-tank of a smaller volume disposed in the supply line connecting the main ink tank and the print head. The print head is therefore maintained in a state of slight negative pressure by reducing the pressure in the sub-tank.

According to the patent specification, “The ink supply device is controlled such that a predetermined amount of ink is stored in the ink chamber of the sub-tank according to the amount of ink ejected from the nozzles. This prevents interruption of the ink supply to the print head.”

As one example, it is controlled to supply ink from the main tank to the sub-tank when the ink level in the sub-tank is detected to have fallen below a predetermined level. As a regular means of detecting the ink level, a structure is disclosed comprised of a float provided with a magnet that is vertically and movably placed to float on the ink and a sensor for detecting magnetism from the magnet is disposed at a predetermined level.