This disclosure relates to an image forming apparatus in which ink is jetted from a head nozzle to record an image on a recording medium, such as a sheet of paper.
An image forming apparatus may take various forms. In one example embodiment, the image forming apparatus takes the form of an inkjet recording apparatus, and includes a head having a plurality of ink-jetting nozzles from which ink is jetted. The ink is supplied to the head from an ink tank.
The inkjet recording apparatus generally includes a pump mechanism disposed in an ink supply path through which the ink is supplied to the head from the ink tank.
In some instances, an ejection state of the pump mechanism may become irregular (i.e., the ink may not eject properly) due to, for example, aggregates contained in the ink, or dust adhering to a surface of the nozzle. In such circumstances, streak-like blanks (i.e., white streaks) may appear in an image as it is recorded.
On these occasions, the inkjet recording apparatus performs a purge operation by jetting a large amount of ink from the ink-jetting nozzle to clean the inside of the nozzle so that the ink ejection state is returned to a normal state. The purge operation is performed by supplying a large amount of ink to the head of the inkjet recording apparatus from the ink tank with the pump mechanism.
However, ink viscosity may vary during the purge operation, causing the purge operation to damage the pump mechanism, or even to fail. The ink viscosity variations may occur as a result of temperature variations. For example, when ink is at low temperature, the ink viscosity becomes higher. Accordingly, when ink having a low temperature is supplied from the ink tank to the head by the pump mechanism, ink pressure may excessively rise in an attempt to ensure the ink makes it to the head.
In such a situation, however, members constituting ink flow paths and/or members constituting the pump mechanism may be damaged due to the excessively raised pressure.
Conversely, when ink temperature is high, the ink pressure becomes lower. Under these circumstances, a desired cleaning effect may not be obtained due to the lack of pressure.
In view of the above-mentioned problem, an inkjet recording apparatus is proposed as one type of image forming apparatus. The inkjet recording apparatus includes a temperature detection portion to detect a temperature, and an operation changing portion to change an operation of a pressurization pump of the inkjet recording apparatus in accordance with a detection result of the temperature detection portion.
USPTO Backgrounds
USPTO Backgrounds