A color printing system for color-printing images or characters on a surface of a writing sheet. The color printing system includes a plurality of printing heads which are successively arranged in parallel to each other and a feeding device for moving the writing sheet in a direction perpendicular to the head-reciprocating directions. Each of the printing heads linearly reciprocates so as to go and return in directions along the surface of the writing sheet for the color printing and has a plurality of ink-discharging nozzles. The plurality of ink-discharging nozzles are successively arranged with a pitch which is equal to or greater than twice the pitch of the finally printed lines so as to write the images or characters on the writing sheet. The feeding device moves the writing sheet in a direction perpendicular to the head-reciprocating directions by predetermined distances. After the printing heads perform the going-direction printing operation, the feeding device moves the writing sheet by a distance cooresponding to M times the line-printing pitch where M is a predetermined number, and after the printing heads perform the returning-direction printing operation the feeding device moves the writing sheet by 2N - M times the line-printing pitch, where N is the number of the ink-discharging nozzles.
In an ink jet printer, a print head includes (N+1) nozzles arrayed in the paper feed direction. The distance between the adjacent nozzles is K times as long as the dot line pitch P. N and K are each an integer larger than 2, and mutually prime. The quantity of ink droplet discharged from each nozzle is adjusted so as to form on a print paper, dots each having the diameter at least 1.4 times as long as the dot line pitch. An interlaced print as the combination of a print of paths made by the N successive upper nozzles of the print head and a paper feed of N print line pitches is used for the print on the most part of the print paper. A minute-feed print as the combination of a print of paths made by the N successive upper or lower nozzles of the print head and a paper feed of one print line pitch is used for the print on the upper and lower end areas of the print paper that reject a perfect print by the interlaced print. With the combination of the interlaced print and the minute-feed print, a perfect print is made on the entire surface of the print paper.
The recording apparatus includes a recording head that performs dot-recording on the recording material through a plurality of recording elements arranged on the recording head; a mechanism to move the recording head in a main scan direction to perform recording; and a transport mechanism to feed the recording material in a sub-scan direction perpendicular to the main scan direction after each main scan operation. The transport mechanism is formed of a combination of driving elements including a driving source. The feeding distance that the recording material is fed in one feeding operation is set synchronized with the driving cycle of the driving elements including the driving source. This arrangement allows the recording head, which has an array of ink ejection nozzles arranged with a conventional density, to produce a dot-recorded image having a resolution two or more times higher than the conventional resolution.
Printing of a unit pixel (1/D=1/600) in 4-pass printing (64 nozzles, and a total sheet supply amount of 62/600 in four operations) is exemplified in an image printing apparatus capable of printing a uniform, high-quality image while avoiding printing of a visually nonuniform image in multipass printing of two or more passes. With an image printing apparatus as described herein, satellites can be uniformly printed on the right and left of a unit pixel.
A recording apparatus is provided with two or more kinds of sub-scanning amounts per main scan, and records a high quality image by reducing the bleeding between colors created characteristically by a multi-pass recording method. The number of times of main scanning to complete an image by a first discharge port array for black ink use and a second discharge port array for color ink use, respectively, are set to be m (m is a positive integer) and n (n is a positive integer) times. With respect to discharge ports to be used for recording in the first and second discharge port arrays, a distance between discharge ports which are positioned at upstream ends of the respective first and second discharge port arrays in the sub-scan direction is made equal to a length of a continuously conveying amount of (m+a) (a is a positive integer) times by combination of the at least two kinds of conveying amounts.
A paper feed operation is performed by a width less than one pixel (1/2) in addition to an integer multiple number of pixels (n/2) with respect to a basic number of pixels inherent to an ink jet recording apparatus having a multi nozzle head having n nozzles. When a plurality of pixel recording operations are performed for a single pixel region, ink dots land within a distance less than one pixel unit (1/2). Thus, a variation in ink surface density on a recording sheet in an overlapping print operation is reduced, thereby efficiently increasing the image density, and preventing blurring by promoting absorption and evaporation of an ink to and from a paper sheet.