1. Technical Field
The present invention relates to a fluid ejecting apparatus that is provided with a fluid ejecting head for ejecting fluid.
2. Related Art
An ink-jet printer is known as an example of various kinds of fluid ejecting apparatuses. An ink-jet printer ejects ink (fluid) onto a recording target medium such as a sheet of printing paper (target medium) from a recording head, which is an example of a fluid ejecting head. Such an ink-jet printer is hereinafter simply referred to as “printer”. When the non-ejection state of a printer, which is a state in which no ink is ejected from the nozzles of a recording head, continues for a long period of time, the surface of meniscus of ink retained inside the nozzles becomes dried. In such a case, there is a risk that the ink-ejection performance of a printer might deteriorate. In order to avoid poor ink ejection, a printer performs so-called flushing operation. In flushing, ink is forcibly discharged through nozzles on the basis of a control signal during a time period in which printing is not performed. This control signal is not related to printing operation.
For example, a serial printer or a lateral printer, which ejects ink from a recording head that moves in reciprocating motion along a plane over which a sheet of recording paper is transported during printing, performs flushing as follows. The serial/lateral printer causes the recording head to move to a non-printing area, which is located outside an area where printing is performed on a sheet of recording paper. A fluid catching unit, which is a catcher for receiving fluid, is provided at the non-printing area. Examples of the fluid catching unit are: a cap, a flushing box, or the like. The printer ejects ink as an example of fluid into the fluid catching unit for the purpose of flushing. A line head printer, which is equipped with a line-type recording head that does not move along a plane over which a sheet of recording paper is transported and is provided at somewhere over a paper transportation path in such a manner that the recording head extends throughout the entire width of the sheet in a direction that is orthogonal to the transportation direction of recording paper, performs flushing as follows. A fluid catching unit such as a cap or the like is configured as a movable member. The line head printer moves the fluid catching unit to a position where the fluid catching unit faces the nozzle formation surface of the recording head at the proximity thereof or in contact therewith. With the fluid catching unit facing the nozzle formation surface of the recording head, the printer ejects ink into the fluid catching unit for the purpose of flushing.
A part of an ink droplet discharged as waste ink into a fluid catching unit such as a cap or the like during flushing operation is formed into mist particles and floats inside the fluid catching unit. Such misty ink (hereinafter may be referred to as “ink mist”) sometimes floats out of the fluid catching unit through an opening that is formed as a part of the fluid catching unit. The opening of the fluid catching unit is an open region that is positioned opposite to a recording head during flushing operation. As an example of printers of late that are equipped with a mechanism for preventing the floating of ink mist to the outside of a fluid catching unit, a printer that is disclosed in JP-A-2001-191557 or JP-A-2002-137415 has been proposed in the art.
The related-art printer that is disclosed in the above patent documents is equipped with a negative pressure generating means that is connected to a fluid catching unit. An example of the negative pressure generating means is a suction pump. The negative pressure generating means operates to apply a suction force to the inside of the fluid catching unit during flushing operation. The internal pressure of the fluid catching unit becomes negative because of suction. Since the negative pressure generating means generates negative pressure inside the fluid catching unit during flushing operation, ink ejected from a recording head as waste ink is sucked by the negative pressure generating means together with air that flows into the fluid catching unit through the opening. Therefore, even when a part of an ink droplet discharged from the recording head as waste ink into the fluid catching unit turns into ink mist, the disclosed mechanism makes it possible to prevent the ink mist from floating out of the fluid catching unit.
The opening of the fluid catching unit is open not only during flushing operation but also during a time period in which flushing is not performed. Therefore, at the time of flushing, the negative pressure generating means sucks not only ink ejected from the recording head as waste ink into the fluid catching unit but also air that flows/flowed into the fluid catching unit through the opening. For this reason, the disclosed printer has a disadvantage in that the burden of the negative pressure generating means is inevitably heavy because it requires extra power due to and corresponding to the greater suction amount of air entering the fluid catching unit through the opening, which is a problem that remains to be solved.