JP2002113904A - Color imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color imaging device capable of smoothing jags and reducing color displacement to the minimum degree by effectively functioning adjusting dots even in the case of recording with two or more colors superimposed, and achieving a high printing quality. SOLUTION: A Y adjusting dot 12 and a C adjusting dot 24 with a diameter larger than the diameter of the Y adjusting dot 12 are provided at a part of an outline 25 of an inclined part or a slant line part with respect to a dot of an ordinary size such as a Y dot 11 and a C dot 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus for obtaining a color image by superposing dots of a plurality of colors, and more particularly to a color image forming apparatus for forming a slanted line or a slanted portion formed of characters and figures. It relates to smoothing.

[0002]

2. Description of the Related Art In conventional image forming apparatuses such as electrophotography and ink jet, characters and figures are drawn as a group of dots in units of pixels. For this reason, when printing is performed by a conventional image forming apparatus, jaggies called jaggies occur at oblique lines and inclined portions of characters and figures, which adversely affects print quality. FIG. 4 is a diagram showing an outline of a hatched portion or an inclined portion. The outline 35 is formed by shifting a plurality of dots 36 one by one to the right in the drawing.

In order to solve this problem, the jaggies of the outline of the hatched portion or the inclined portion are reduced by adding an adjacent dot to the outline or the dot itself as an adjustment dot smaller than a dot of a normally used prescribed value and adding the adjustment dot. There is a way.

[0004]

Conventionally, color image forming apparatuses use C (cyan), M (magenta), Y (yellow), and K (black) developers and inks,
When drawing characters and figures in colors other than MY,
Recording is performed with Y superimposed. For example, drawing in a green color can be generally realized by overlapping C and Y colors.

As described above, when C, M, and Y are superimposed and recorded, it is necessary to match the superimposition positions of the C, M, and Y, but it is often difficult to superimpose the C, M, and Y at the same position. However, there has been a problem that a so-called dot shift occurs in which dots cannot be overlapped at the same position.

In the case where an adjusting dot is added as in the prior art, for example, when a character or a figure is drawn in the color of green, as shown in FIG.
With respect to a dot having a normal size as described above, both the Y adjustment dot 22 and the C adjustment dot 24 are attached to the portion located on the contour 25 of the inclined portion or the hatched portion. However, in such a case, the above-described dot shift is involved, and as shown in FIG. 5, the Y adjustment dots 22 and the C adjustment dots 24 are recorded with a shift, and are recognized as substantially large dots. There is a problem that the smoothing effect of the goats is weakened, and this tendency is particularly remarkable when C and M are mixed.

In order to solve this problem, when recording is performed using multiple colors such as C, M, Y, etc., there is a method of improving the jaggy smoothing effect by adding only one color adjustment dot. See JP-A-4-269774).

[0008] However, in such a case, although a certain smoothing effect is given to the jaw, there is a case where a color shift in a thin line is observed, and there is a problem in color reproducibility especially in a thin line. Was.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a plurality of recording units for recording a one-color image on paper or an image carrier. When reproducing a desired color by combining a plurality of recording units with different colors for the oblique and oblique portions, the diameter of the dot located at the contour of the oblique line or oblique portion is changed to the standard dot diameter. In a color image forming apparatus that uses a smaller adjustment dot to make a recording result look smoother, a color image forming apparatus that includes an outline detection unit that controls the size of the adjustment dot to be different for each recording unit and records the image. It is a device.

The term "recording" in the present invention refers to developing a developer on an image carrier or paper in the case of a color image forming apparatus by electrophotography, and in the case of a color image forming apparatus by ink jet or the like. Means jetting ink on paper.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view schematically illustrating a color image forming apparatus of the present invention. Reference numeral 1 denotes a color image forming apparatus main body. Reference numeral 2 denotes a photoconductor drum, and a photoconductor such as OPC or a-Si is used. Reference numeral 3 denotes a charging roller, which is configured so that a predetermined bias voltage can be applied to the surface of the photosensitive drum 2 from a power source (not shown). Reference numeral 4 denotes an exposure unit that irradiates image information from an external terminal to the charged surface of the photosensitive drum 1 with a laser beam to form a latent image. In this case, LED light may be used.

Reference numeral 5 denotes a developing device for developing a color toner on the formed latent image.
(Yellow) developing device 5a, M (magenta) developing device 5b, and C (cyan) developing device 5
A developing device 5d for developing c and K (black) is arranged.
Each developing unit 5 includes a toner container 50a containing yellow toner, a developing container 51a for developing toner supplied by a supply roller 52a, and a toner container 50b containing magenta toner and a supply roller 52b. A developing container 51b for developing the replenished toner includes
A toner container 50c containing cyan toner and a developing container 51 for developing toner replenished by a replenishing roller 52c
c is a toner container 5 further containing a black toner
A developing container 51d for developing the toner supplied by the supply roller 52d and the supply roller 52d is disposed above the color image forming apparatus. In the present embodiment, non-magnetic toner is used as the toner of each color. Reference numeral 31 denotes a cleaning unit, which removes toner that has not been transferred on the intermediate transfer drum 6 described below from the photosensitive drum 2.

Reference numeral 6 denotes an intermediate transfer drum, which performs a color transfer by repeating the operation of temporarily transferring the toner developed on the photosensitive drum 2 by applying a predetermined bias for each toner. 6a is a secondary transfer roller, 6b
Denotes a cleaning roller. Although not shown, the secondary transfer roller 6a and the cleaning roller 6b are provided with a retracting mechanism for retracting from the intermediate transfer drum 6 until the respective colors are completely overlapped.

Reference numeral 7 denotes a paper feed unit, which is a paper feed unit that has a large amount of paper stacked under the color image forming apparatus 1 and that conveys the uppermost paper by a paper feed roller 70.
a and a manual feed unit for transporting sheets one by one. The sheet sent from the sheet feeding means 7 is conveyed to the registration roller 60, and is sent to the secondary transfer roller 6a after the leading edge is aligned. Then, after the color-superimposed toner is transferred onto the sheet by the intermediate transfer drum 6, the sheet is conveyed toward the outlet side by the conveyance belt 8. Reference numeral 9 denotes a fixing unit, which is disposed near the exit side and fixes the secondary-transferred toner to the sheet by heat and pressure.

Numeral 10 denotes a paper discharging means, which is a face-up tray 10a for discharging the paper thermally fixed by the fixing means 9 with the printing surface up and a face-down tray 10b for discharging the paper with the printing surface down. Is arranged.

FIG. 2 is a diagram showing an algorithm of a contour detection unit provided in the image forming apparatus and used for detecting a portion of a character or a figure which requires a smoothing of a slanted portion or a slanted portion. The detecting unit expands the print data on the memory of the printer main body or the host side, compares the print data with data stored in advance, and detects an edge that requires smoothing in the print data. Is detected, and adjustment dots calculated from the detected result are generated to perform smoothing.

The present invention is characterized in that the contour detecting section generates adjustment dots corresponding to the respective developing units 5a to 5c differently from each other so as to correspond to a dot shift at the time of color superposition. By making such a difference, even when two or more colors are superimposed and recorded, the adjustment dots can be effectively operated to minimize the jagged smoothing and color shift of the hatched portion or the inclined portion, and color reproduction can be achieved. Gender is not affected.

In particular, weighting is performed on C, M, and Y, and M>
It is preferable to control the size of the adjustment dot so that C> Y or C>M> Y. This is Y
C and M have a greater effect on color reproducibility than
It is an object of the present invention to perform recording in three colors without using K, and to increase the size of the adjustment dots of the colors that are easily recognized by human eyes among them. The sizes of the M and C adjustment dots may be substantially the same. Further, as a method of adjusting the size of the adjustment dot, a method of changing a laser power applied from the exposure unit 4 to the photoconductor drum 2 can be used.
A method of varying the beam diameter at a position where the exposure unit 4 irradiates the photosensitive drum 2 or a method of varying the image forming processing speed including the photosensitive drum 2 may be performed.

For example, when printing a diagonal line or a slanted part of a character or a figure with a green color by such a contour detection unit, as shown in FIG. For the dot having the size, the Y adjustment dot 12 and the C adjustment dot 24 having the diameter of the dot larger than the diameter of the Y adjustment dot 12 are attached to the portion located at the contour 25 of the inclined portion or the oblique line portion. As a result, the jaw level of the contour 15 can be improved as compared with the conventional contour 25 shown in FIG.

[0021]

As described above, according to the color image forming apparatus of the present invention, two or more colors are superimposedly recorded in order to record the adjustment dots with different sizes for each recording section. Even in this case, the adjustment dots are made to act effectively to minimize the jagged smoothing and color misalignment of the hatched and inclined parts,
Further, it is possible to provide a color image forming apparatus capable of achieving high quality printing quality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a color image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating an algorithm of a contour detection unit according to the present invention.

FIG. 3 is a diagram showing a recording result of the present invention.

FIG. 4 is a diagram showing a conventional recording result.

FIG. 5 is a diagram showing a conventional recording result.

[Explanation of symbols]

1: color image forming apparatus main body 2: photosensitive drum 3: charging roller 4: exposure means 5, 5a to 5d: developing device 50a to 50d: toner container 51a to 51d: developing container 52a to 52d: supply roller 31: cleaning means 6: The toner that has not been transferred on the intermediate transfer drum 6 is removed from the photosensitive drum 2. 6a: secondary transfer roller 6b: cleaning roller 7: paper supply unit 70: paper supply roller 7a: paper supply unit 60: registration roller 8: transport belt 9: fixing unit 10: paper discharge unit 10a: face-up tray 10b: face Down tray 11, 21: Y dot 12, 22: Y adjustment dot 13, 23: C dot 14, 24: C adjustment dot 15, 25, 35: Outline 36: Dot

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H04N 1/46 H04N 1/46 Z 5C079 F term (Reference) 2C056 EA04 EA11 EB29 EB58 EC07 EC69 EE09 2C262 AA02 AA04 AA24 AA26 AB13 BB10 DA03 DA08 DA12 2H030 AA01 AD11 BB02 BB12 5B057 AA11 CA01 CA16 CB01 CB16 CE02 CE06 CE16 DB02 DB06 DC16 5C074 AA02 AA10 BB02 BB16 CC26 DD05 DD24 EE12 FF11 FF15 GG09 LA02 LAH

Claims (2)

[Claims] A plurality of recording sections for recording one-color images on a sheet or an image carrier, and oblique lines or oblique portions of characters, figures, or the like are formed for each dot by a combination of different colors depending on the plurality of recording sections. When reproducing a desired color, a color image forming apparatus that makes the contour look smoother by using an adjustment dot whose diameter is smaller than the diameter of a standard dot located at the contour of the hatched portion or the inclined portion. 3. The color image forming apparatus according to claim 1, further comprising an outline detection unit configured to control the size of the adjustment dot to be different for each of the recording units. 2. The printing apparatus according to claim 1, wherein the recording unit comprises three recording units for recording at least each color of cyan, magenta, and yellow, and the contour detecting unit determines the size of the adjusting dot by cyan>magenta> yellow. 2. The color image forming apparatus according to claim 1, wherein control is performed such that magenta>cyan> yellow.