1. Field of the Invention
The present invention relates to a recording apparatus for recording an image onto a recording sheet by a recording head.
2. Description of the Related Art
A recording apparatus is constructed so as to record an image onto a recording sheet such as paper, plastic sheet, or the like based on image information. The recording apparatuses can be classified into an ink jet system, a wire dot system, a thermal system, a laser beam system, and the like according to a recording system. In a recording apparatus of a serial type using a recording head which moves in the width direction of the recording sheet, the recording is executed to the whole recording sheet while alternately repeating the recording of an amount corresponding to one line and the conveyance of a predetermined pitch. In a recording apparatus of a line type which records only by a scan in the conveying direction of the recording sheet, the recording of the whole recording sheet is executed by executing the conveyance of the predetermined pitch while continuously executing the recording of one line in a lump.
FIG. 14 is a partial vertical sectional view of a recording apparatus of the related art. In FIG. 14, a recording head 1301 executes the recording by discharging ink onto a recording sheet S1. A platen 1302 supports the recording sheet S1 at a position where it faces the recording head 1301. A conveying roller 1303 conveys the recording sheet S1 on the upstream side of the recording head 1301 in the conveying direction of the recording sheet. A pinch roller 1304 generates a conveying force by coming into pressure contact with the conveying roller 1303. A sheet discharge roller 1305 ejects the recorded recording sheet S1 to the outside of an apparatus main body. A driven roller 1306 such as a spur or the like generates a conveying force by coming into pressure contact with the sheet discharge roller 1305. The recording apparatus is constructed in such a manner that a pressure contact point of the pinch roller 1304 to the conveying roller 1303 is deviated at the downstream side in the conveying direction of the recording sheet, thereby pressing the recording sheet S1 onto the platen 1302. A nip portion 1308 is formed between the sheet discharge roller 1305 and the driven roller 1306.
However, in the case of pressing the recording sheet onto the platen by deviating the pressure contact point of the pinch roller, an optimum position of the pinch roller differs depending on conditions such as recording sheet type, conveying conditions, environmental conditions, ink type, image forming area, and the like. Among those various kinds of conditions, there are also conditions which are reciprocal to one of a movement amount and the moving direction. Therefore, a certain margin is allowed for recording quality by using a method whereby the apparatus is designed based on an intermediate value of an optimum value, a method whereby design values are determined by weighting each recording condition, or the like.