JPH06152898A - Color ink jet recording method - Google Patents

Abstract

PURPOSE:To realize the compatibility of black ink with color ink in color recording without ink blotting by properly using black by means of black ink and black by means of plural kinds of color ink in accordance with the frequency of black recording picture element within a specified area. CONSTITUTION:Data is transferred from a host computer 306 and data stored in a reception buffer 307 is read by a system controller 301. Read data is stored after extending data corresponding to the respective kinds of color in the respective frame memories 308 of C, M, Y and Bk. The area recorded in a recording medium is divided into specified areas M and the black frequency within the area M is checked. It is judged whether the number expressing the black frequency is more than a value fixed as a specified value C or is equal to below the specified value C. When it is equal to or below the specified value C, recording is executed as in a conventional manner so that black is recorded by Bk ink. When it is more than the specified value C, Bk data within the area M is re-extended to C, M and Y data so that black is recorded by C+M+Y.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color ink jet recording method capable of recording a color image clearly and in high density. More specifically, it is specifically related to yellow (Y), magenta (M), cyan (C) or green (G). ), Red (R), blue (B) ink, and black (Bk) ink.

[0002]

2. Description of the Related Art Ink jet recording methods are used in printers, copying machines, facsimiles and the like because of their low noise, low running cost, easy miniaturization of devices, and easy colorization.

In general, a color ink jet recording method uses three color inks of cyan, magenta and yellow, and further four color inks with black added for color recording.

[0004]

In the conventional ink jet recording method, it was necessary to use a special paper having an ink absorbing layer in order to obtain a color image of high color development without ink bleeding. Due to the improvement of the method, a method in which printing suitability for plain paper, which is used in large quantities in printers and copying machines, has been put into practical use. However, the printing quality on plain paper has not yet reached a sufficient level. The most significant factor is compatibility between ink bleeding between the colors and black recording quality (particularly black characters and fine line recording quality).

Usually, when a color image is obtained on a plain paper by an ink jet recording method, a quick-drying ink having a high penetration speed into the plain paper is used. For this reason, the image does not have ink bleeding between each color, but the density is low overall, and around the recorded image area of each color, a slight amount of ink bleeds along the fibers of the paper, so-called feathering occurs. It's easy to do.

Feathering is relatively difficult to notice in a color image area, but is easily noticeable in a black image area, resulting in deterioration of recording quality. In particular, when the black image is a character or a thin line, it becomes an unclear character lacking sharpness and its quality is poor.

Therefore, in order to obtain a high-quality black record with little feathering and high density, it is necessary to use black ink having a relatively slow penetration rate into plain paper. However, in this case, ink bleeding of each color occurs at the adjacent boundary portion between the recording image areas of each color of black and color, and the quality is impaired.

As described above, the improvement of color recording quality by preventing ink bleeding between each color of black and color and reducing the feathering of black in particular has been a contradictory issue.

Therefore, Japanese Laid-Open Patent Publication No. 3-146355 proposes a method of not recording an area along the boundary area between black and color. However, this method has a drawback that a part of recorded data is lost.

Further, in Japanese Patent Laid-Open No. 4-158049, a multicolor head for color recording and a head for character recording are provided, and the multicolor head and the character recording head are switched based on a recorded image. A method of recording is proposed. However, in this method, in addition to the conventional multi-color head for color recording, a head for character recording is provided, so that cost increase and device enlargement are inevitable.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is to keep the black recording quality of characters, fine lines, etc. sharp, and to keep black and each color. The aim is to achieve both high-quality color recording without ink bleeding.

[0012]

In order to achieve this object, the present invention uses a black ink and a plurality of color inks having different recording medium penetrating characteristics from the black ink, In a color ink jet recording method for recording a color image on a recording medium, it is determined whether or not the recording frequency of black in a specific area on the recording position of the recording medium is larger than a specific value, and according to the determination result It is characterized by selecting whether to record black with a plurality of color inks or black ink.

As a result, black of black ink and black of a plurality of color inks are selectively used according to the recording frequency of black in a specific area on the recording medium.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of a recording apparatus for carrying out the ink jet recording method of the present invention.

A carriage 101 has a print head 102 and a cartridge guide 103 mounted thereon, and guide shafts 104, 10
5 can be scanned (driving not shown).

The recording paper 106 is fed into the main body by a paper feed roller 107, is pinched by a paper feed roller 108 and a pinch roller (not shown), and is sandwiched by a paper pressing plate 109 and is fed to the entire surface of the paper feed roller 108 for printing. It Two types of ink cartridges, a color ink cartridge 110 containing three colors of yellow, magenta, and cyan, and a black ink cartridge 111 are separately inserted into the cartridge 103 and communicate with the print head 102.

The yellow, magenta, and cyan inks stored in the color ink cartridge 110 are those that have a high penetration speed into the recording paper so that ink bleeding does not occur at color boundaries when forming a color image. Used. On the other hand, the black ink stored in the black ink cartridge 111 is relatively high in recording paper as compared with the above three types of color inks so that the black image has high density and high quality with less ink bleeding. Those with a slow penetration rate are used.

The print head 102 is shown in FIG. Yellow, magenta, cyan, and black ejection port groups are arranged on the front surface of the print head 102 in a straight line. Each group has 2 for yellow, magenta and cyan
Each of them has four discharge ports for black, and 64 discharge ports for black.

Each of these ejection ports is provided with an ink liquid passage communicating with the ejection port, and a common liquid for supplying ink to these liquid passages is provided behind the portion where the ink liquid passage is provided. A room is provided. The ink liquid path corresponding to each of the ejection ports is provided with an electrothermal converter that generates thermal energy used for ejecting ink droplets from these ejection ports and electrode wiring for supplying electric power to the electrothermal converter. ing. These electrothermal converters and electrode wirings are formed on the substrate 201 made of silicon or the like by a film forming technique. Further, the ejection port, the ink liquid passage, and the common liquid chamber are formed by stacking a partition wall made of a resin, a glass material, a top plate, etc. on the substrate. Further on the rear side, a drive circuit for driving the electrothermal converter based on a recording signal is provided in the form of a printed circuit board.

The silicon substrate and the printed circuit board 202 are attached to the same aluminum plate 203, and the pipes 204, which protrude in parallel with the aluminum plate 203.
Reference numeral 207 projects from a plastic member 208 called a distributor that extends in a direction perpendicular to the silicon substrate, and further communicates with a flow passage therein, and the flow passage communicates with a common liquid chamber.

There are four channels in the distributor for yellow, magenta, cyan and black.
A pipe is connected to each common liquid chamber.

About 40 ng from the yellow, magenta, and cyan discharge ports provided on the print head 102.
Ink is about 80n from the black discharge port.
g of ink is ejected.

The components of the used ink are as follows.

1. Y (yellow) C.I. I. Direct Yellow 86 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water balance

2. M (magenta) C.I. I. Acid Red 289 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water balance

3. C (cyan) C.I. I. Direct Blue 199 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water balance

4. Bk (black) C.I. I. Direct Black 154 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Water balance

As described above, C, M and Y have improved permeability by adding 1% of acetylenol EH to Bk. In addition to this, other additives include other surfactants, alcohols and the like.

FIG. 3 is an electrical control block diagram of the color ink jet recording apparatus described above.

Reference numeral 301 denotes a system controller for controlling the entire apparatus, and a storage element (ROM) in which a control program including a microprocessor is stored inside,
A memory element (RAM) and the like used when the microprocessor performs processing are arranged.

Reference numeral 302 is a driver for driving the print head in the main scanning direction, and similarly 303 is a driver for moving in the sub scanning direction. 304 and 305 are motors corresponding to the driver, which are speeds from the driver,
It operates by receiving information such as travel distance.

A host computer 306 is a device for transferring information to be printed to the printing device of the present invention.

Reference numeral 307 is a reception buffer for temporarily storing data from the host computer.
Data is accumulated until it is read from the system controller of.

A frame memory 308 expands each color data to be printed into image data, and has a memory size for printing. In this embodiment, a frame memory capable of storing one print sheet will be described, but the present invention is not limited to the size of the frame memory.

Reference numeral 309 is a storage element for temporarily storing each color data to be printed, and the storage capacity changes depending on the number of nozzles of the print head.

Reference numeral 310 denotes a print control unit for appropriately controlling the print head according to a command from the system control, and a print control unit for controlling the ejection speed, the number of print data, and the like.

311 is 312Y, 312M, 312C,
A driver for driving a 312 Bk head,
It is controlled by a signal from the print control unit 310.

FIG. 4 is an operation flow of the first embodiment. The part surrounded by the broken line is a characteristic part of the present invention.

In STEP 1, the host computer 30
6, the system controller 301 reads data stored in the reception buffer 307.

In STEP 2, the read data is C,
Data corresponding to each color is developed and stored in each of the M, Y, and Bk frame memories 308.

In STEP 3, the area to be recorded on the recording medium is divided into specific areas M, and the black recording frequency in the area M is checked. Specifically, as shown in FIG.
The recording data for one A4 size sheet stored in the frame memory is composed of 4 dots vertically and horizontally for a total of 16
The image is divided into specific areas M each including pixels, and the number of Bk recording pixels in each specific area M is counted. Here, it is determined whether this number is more than the two specified as the specific value C or is less than or equal to the specific value C. If No, that is, if it is less than or equal to the specific value C, the process directly proceeds to STEP 5. This is the same recording as the conventional one, and black is recorded with Bk ink. If Y, that is, more than the specific value C, the process proceeds to STEP 4.

In STEP 4, the Bk data in the specific area M is re-developed into C, M and Y data to eliminate the Bk data. That is, black is recorded as C + M + Y.
Then proceed to STEP5.

At STEP 5, the recording operation is performed as in the conventional case, and then the series of operations is ended.

In the processing of STEP 4, the bleeding of the Bk ink and the color ink on the recording medium, that is, the occurrence of bleeding depends on the frequency of black pixel recording in the specific recording area M, and is higher than a certain value. Is a process in which bleeding is likely to occur, and conversely, bleeding is less likely to occur at a frequency lower than a certain value.

The processing of STEP 4 is processed by software by an internal program in the system controller 301. This processing is not limited to this, and may be implemented by an electric circuit that is hardware in order to perform processing at higher speed, for example.

In this embodiment, the pixel pitch P is about 70.56 μm and the recording density is 360 dpi. Therefore, the number of recording pixels for recording A4 full size is about 2600 in the horizontal direction and about 3600 in the vertical direction.
The number of specific areas M is about 650 in the horizontal direction and about 900 in the vertical direction because the area is 4 × 4 pixels.

FIG. 7 is an example showing an image in which a black image and a color image are mixed on one sheet of recording paper.

The image portion A is a natural image such as a photograph, and is generally an image having a portion in which black recording pixels are frequently generated. At this time, the black recording portion expresses black by superimposing the three colors of C, M, and Y. This black is a relatively blurred black with a low OD, but since the CMY ink has a characteristic that it hardly bleeds, there is no color bleeding with other color recording parts,
The result is a high-quality image as a whole.

On the other hand, the image area B is an image in which black recording pixels are rarely generated, as in mechanical and electrical drawings. At this time,
The black recording portion expresses black with Bk ink. This black has no feathering and has a high OD, and thin lines and small characters are sharply recorded.

The right side of FIG. 7 is a character portion. Of the character part,
Regarding the portion recorded in black, the thin portion expressing the character is recorded in Bk, and the central portion of the thick portion is recorded in C + M + Y. At this time, bleeding occurs in the Bk part and the CMY part, but since both are black, there is no problem.

The value of the specific value C varies depending on the density of recording pixels, the characteristics of the ink used, the characteristics of the recording medium, the time from the recording of Bk ink to the recording of another color ink, and the like. Becomes Therefore, the optimum value is selected depending on the recording system used.

Although the case where a frame buffer for recording one page is provided is shown here, the present invention can be applied even if a line buffer is provided instead of the frame buffer.

(Second Embodiment) In the first embodiment, the case where the entire recording area is divided into the specific areas M and processed is shown. However, depending on the case, as shown in FIG. 8, even if the black recording frequency is low in the divided specific area M, the black recording pixels may be partially hardened in a continuous area. In this case, bleeding that occurs in the black recording area and the recording areas of other colors around the black recording area can be avoided by overlapping the same recording pixel in the vertical and / or horizontal directions and making the determination in STEP4. .

Specifically, as shown in FIG. 6 as an example, each pixel is used as a mask in which the specific region M is shifted by 1/2 in the vertical and horizontal directions, except for the periphery of the maximum recording region, twice. The determination process of STEP 4 is performed for each. The logical sum of the determination results of the overlapping processing for the same pixel is the determination result in this case. The calculation processing time is longer than that in the first embodiment, but the processing is more reliable.

(Third Embodiment) In the first embodiment, the case where the entire recording area is divided into the specific areas M each having four pixels in the vertical and horizontal directions and processed is shown.

This is not limited to this set of pixels, but may be a region M of m × n (m and n are integers of 2 or more) pixels in general. Further, in this case, the optimum value is selected as the value of the specific value C.

(Fourth Embodiment) In the first embodiment, the algorithm is simplified for easier and faster processing, and STEP4
Then, the recording frequency of the black pixel recording data in the specific area M is calculated, and the processing based on the result is performed.

Originally, the occurrence of bleeding between Bk and other colors occurs due to the interaction between Bk and other colors. Therefore, the specific value C may be a larger value depending on the recording frequency of C and / or M and / or Y in the specific area M.

FIG. 9 shows the frequency of color recording pixels in the specific area M, that is, the recording frequency in the specific area with respect to the total value T of the recording pixels of C, M, and Y (T (m × n) × 100%, m).
= 4, n = 4), it is a diagram illustrating the frequency of black recording pixels that can be recorded with Bk ink. In this example, the value of the specific value C is increased as the frequency of occurrence of color recording pixels in the specific area decreases. In the first embodiment, only the portion A is N
Although it was o, it was expanded to the part of B.

In this example, bleeding does not occur,
In addition, it is possible to use the Bk ink with a higher probability, and there is an advantage that the high quality black recording area can be further expanded.

The present invention has been described with reference to the embodiments. In the above embodiments, the recording head has been described by using the jet recording method in which bubbles are generated in the ink by using the thermal energy generated from the electrothermal converter and the ink is ejected by the action of the bubbles. It goes without saying that the present invention is also applicable to a so-called piezo type inkjet recording system in which the ink is ejected by causing a change in the state of the ink by using mechanical energy generated from the mechanical converter.

The present invention is also applicable to paper, cloth, non-woven fabric, and O
Applicable to all devices that use recording media such as HP paper,
Specific applicable devices include printers, copying machines, facsimiles, and the like.

[0064]

As described above, according to the present invention, a black ink and a plurality of color inks having different penetrating speeds are used, and the black ink is blacked according to the frequency of black recording pixels in a specific area. High-quality color recording that keeps good black recording quality such as characters and fine lines and does not cause ink bleeding between black and color by selectively using black with ink or black with multiple color inks It becomes possible to achieve both.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus to which the present invention can be applied.

FIG. 2 is a head mechanism diagram of an inkjet recording apparatus to which the present invention can be applied.

FIG. 3 is a block diagram of an inkjet recording apparatus control circuit to which the present invention is applicable.

FIG. 4 is a diagram showing an operation flow of the first embodiment.

FIG. 5 is a diagram showing a relationship between a recording area and a specific area.

FIG. 6 is a diagram showing a relationship between a recording area and a specific area overlapping with the recording area.

FIG. 7 is a diagram in which black and color are mixed.

FIG. 8 is a diagram showing black recording pixels in a specific area.

FIG. 9 is a diagram showing a relationship of the frequency of black pixels recordable with black ink with respect to the frequency of color recording pixels in a specific area.

[Explanation of symbols]

101 Carriage 102 Print Head 103 Cartridge 104 Guide Axis 105 Guide Axis 106 Recording Paper 107 Paper Feed Roller 108 Paper Feed Roller 109 Paper Pressing Roller 110 Color Ink Cartridge 111 Black Ink Cartridge 201 Silicon Substrate 202 Printed Circuit Board 203 Aluminum Plate 204 to 207 Distributor 208 Prosthetic member 301 System controller 302 Carriage motor driver 303 Paper feed motor driver 304 Carriage motor 305 Paper feed motor 306 Host computer 307 Receive buffer 308Y, 308M, 308C, 308Bk Frame memory for each color 309Y, 309M, 309C, 309Bk Data buffer for each color 310 print control unit 311 print Driver 312Y, 312M, 312C, 312Bk each color of the print head

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nao Yaegashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A color inkjet recording method for recording a desired color image on a recording medium using black ink and a plurality of color inks having different recording medium penetration characteristics from the black ink. It is determined whether the recording frequency of black in a specific area on the recording position of the medium is larger than a specific value, and black is recorded with multiple color inks or black ink according to the determination result. A color ink jet recording method, which comprises selecting whether or not to perform. 2. If the determination result is larger than the specific value, black is recorded with a plurality of color inks, and if it is less than the specific value, black ink is recorded. The color inkjet recording method described in. 3. The black recording pixel occurrence frequency in the specific area is determined a plurality of times at the same recording position on the recording medium,
The color inkjet recording method according to claim 1, wherein the color inkjet recording method is performed based on a logical sum of the determination results. 4. The size of the specific area has a minimum recording pitch P.
2. The color inkjet recording method according to claim 1, wherein the size is 2P × 2P or more, where P is P. 5. The color ink jet recording method according to claim 1, wherein the specific value is larger as the frequency of occurrence of recording pixels other than black in the specific area is smaller. 6. The color ink jet recording method according to claim 1, wherein the ink ejection amount per pixel of each color ink of the plurality of colors is smaller than the ink ejection amount per pixel of black ink. 7. The color ink jet recording method according to claim 1, wherein the ink is ejected by causing a state change in the ink by using heat energy generated from the electrothermal converter. 8. The color ink jet recording method according to claim 1, wherein the ink is ejected by causing a state change in the ink by using mechanical energy generated from the electromechanical converter.