1. Field of the Invention
The present invention relates to an image recording apparatus and an image recording method in which a recording medium is fed by a feeding device based on a target feed amount and an image is recorded on the recording medium by a recording device. In particular, the present invention relates to the image recording apparatus and the image recording method in which the target feed amount is corrected.
2. Discussion of Related Art
There has been known an inkjet printer as an image recording apparatus which records an image on a recording sheet as a recording medium while the recording medium is intermittently fed. In the inkjet printer, a pair of rollers that are opposed to each other cooperate with each other to nip the recording sheet and feed onto a platen. When the recording sheet reaches the platen, the pair of rollers are intermittently rotated and driven by a predetermined feed amount. When the pair of rollers are temporarily stopped and the recording sheet is stopped on the platen, a recording head (a printhead) is reciprocated while the recording head is ejecting droplets of ink toward the recording sheet. The droplets of ink which are selectively ejected from the recording head are landed on the recording sheet such that a desired image is formed on the recording sheet. Because the above-mentioned operation is repeatedly performed, an image recording is sequentially performed from a top end or a leading end of the recording sheet to a bottom end or a trailing end thereof.
In the above-mentioned printer, a problem which is called “banding” may occur in a recorded image on the recording sheet. The banding is sometimes referred to as “white banding” or “stripe of light color”, or “black banding” or “stripe of dark color”. Although there are various causes of “banding”, one of the causes is due to extension or contraction (expansion or contraction) of the recording sheet. In the inkjet printer, it is known that the recording sheet is elongated or contracted when droplets of ink are landed on and permeated into the recording sheet. An amount of the extension or contraction of the recording sheet differs in a grain (fiber) direction in the sheet. In general, a sheet in which the grain direction is a lengthwise (longitudinal) direction or a machine direction of a cut sheet is referred to as “a machine-direction oriented sheet”, and a sheet in which the grain direction is a cross direction of the cut sheet along a short side thereof is referred to as “a cross-direction oriented sheet”. In a case where an image recording is performed such that the recording sheet is fed in the lengthwise direction of the recording sheet, it is generally mentioned that an amount of extension due to ink permeation of the cross-direction oriented sheet is larger than that of the machine-direction oriented sheet.
In the inkjet printer, in a case where the image recording is performed, e.g., in such a manner of interlacing, an area of the recording sheet on which the ink droplets are landed is extended, while another area of the recording sheet in which the image recording is not performed and in which a pair of feed rollers nip the recording sheet is not extended. In a case where the ink droplets are landed on a portion of the recording sheet corresponding to a portion between each pitch of a plurality of nozzles of the recording head in order to record an image of high resolution on the recording sheet, the recording sheet is fed by the feed rollers based on a feed amount depending on the pitch of the nozzles and a desired resolution. Since the area of the recording sheet on which the ink droplets are ejected from the recording head is extended, the ink droplets are landed in a position of the recording sheet that is located out of alignment with a targeted position thereof. Therefore, the banding occurs in the recorded image on the recording sheet.
Japanese Patent No. 2,786,234 (Patent Document 1) discloses that, as a volume of ink that is ejected from a recording head becomes larger, an amount of movement of the recording sheet relative to the recording head is controlled to become larger.
In Patent Document 1, the banding is reduced, but the amount of movement of the recording sheet relative to the recording head becomes larger, so that a recorded image on the recording sheet is stretched longer in a direction of movement of the recording sheet relative to the recording head. In a case where an image is recorded on a roll paper as the recording sheet as disclosed in Patent Document 1, the recording sheet can be elongated enough to correspond to the stretched image. In a case where an image is recorded on a cut sheet as the recording sheet, such problems occur that a margin of a bottom end of the recording sheet comes to be small or that a part of the image cannot be recorded on the recording sheet.
In a case where the feed amount of the recording sheet is made smaller when the recording sheet is contracted, for example, in a borderless printing on a cut sheet, a length of an image that is recorded on the cut sheet as the recording sheet becomes smaller, so that a margin is formed on a side of the bottom end of the recording sheet.