JPH0583375B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color recording device, and particularly to a full-color inkjet recording device that performs recording by jetting ink as minute droplets onto a recording medium.

[Prior Art] Conventionally, when a color image is reproduced using a color inkjet printer, ink of three colors, cyan, magenta, and yellow, is contained in each ink cassette, and the ink is connected from there by a supply tube. The liquid is guided to the nozzle for each color, and discharged from the nozzle.
A subtractive color mixing method using three primary colors was used, which was mixed on the recording medium.

A device that moves a recording medium at a feed pitch for each nozzle section using an inkjet recording head that has nozzle sections that eject ink of three different colors integrally in a nozzle array and each nozzle section sequentially for each color. This is described in Japanese Patent Application Laid-Open No. 56-8266. However, this publication does not disclose three types of ink, magenta (M), yellow (Y), and cyan (C), and there is no suggestion about black ink, which is often used in recorded images.

The structure of a conventional color inkjet printer similar to this is schematically shown in FIG. That is,
The ink tanks 6 for cyan (C), magenta (M), and yellow (Y) and the three nozzles 2 for ink jetting are connected by ink supply pipes 7, and are printed based on external printing commands Pr. The arithmetic unit 4 that measures the ejection timing drives one or more nozzles 2 via a driver 3 to eject ink onto one dot on the recording medium 1 in order to develop a desired color.

Admittedly, this method of expression does not require the use of multiple colored inks, and has its attendant advantages. However, it is known that great difficulties are encountered when trying to obtain a color image that is faithful to the image information, highly detailed, and has a high dot density using this method. For example, in the subtractive color mixing method, other colors must be developed by mixing the above three colors, and the accuracy of the landing point greatly influences the accuracy of the color development.
Ghosts and moiré also occur, which impedes faithful reproduction of images. In view of this point, in order to improve the accuracy of the impact point, the most advanced technology is required for the processing accuracy and assembly accuracy of each nozzle 2. Furthermore, it was necessary to cover various characteristics caused by the physical properties of recording ink, such as delayed ejection timing and slow flying speed of ink droplets, and to back up the system to shoot ink droplets at the same point. .

Further, the mixing of inks is performed on the recording medium 1 (mainly paper), and when it is desired to develop color by mixing, the ink droplets are further overprinted. For this reason, the color spot becomes larger than the color spot formed by one monochromatic dot, resulting in a change in color tone. Furthermore, when ink droplets overlap, it often causes ink to flow out, resulting in image deterioration.Also, because there is another ink droplet ejected previously where the ink droplet lands, it is caused by rebound. The splash is intense and can stain the recording medium, and the splashed droplets can adhere to the tip of the nozzle, distorting the ejection direction and impairing the accuracy of the ink droplets.In addition, ink can accumulate at the tip of the nozzle, making it impossible to eject. It has also been known to fall.
In addition, when expressing black, yellow (Y),
Since it is expressed by mixing all the colors of magenta (M) and cyan (C), there is also the drawback that it is impossible to prevent the brightness from dropping further and giving a dark and depressed feeling.

Therefore, based on the above drawbacks, yellow (Y),
A color inkjet printer that performs color recording using seven colors of ink: magenta (M), cyan (C), black (B), red (R), green (G), and blue (BL) was developed in 1983. -53445.
However, in this invention, recording is performed using a total of 21 heads, three for each color.

FIG. 2 schematically shows the structure of such a color inkjet printer. In the figure, in addition to the three-color ejection system consisting of an ink tank 6 for yellow (Y), magenta (M), and cyan (C), a supply pipe 7, and a nozzle 2, there is also an ink jet system for black (B) and green (G). Equipped with four color injection systems: , red (R), and blue (BL).
It is configured to perform dot expression using seven colors, including the three primary colors Y, M, and C and the four colors obtained by mixing them. Of course, the ejection timing of each of the seven color ejection systems is controlled by the arithmetic unit 4 via the driver 3 in accordance with the external printing command Pr.

[Problems to be Solved by the Invention] However, when performing monochrome recording with a color inkjet recording apparatus having such a configuration, recording can only be performed at the same recording speed as when color recording is performed. Therefore, the color inkjet recording apparatus having such a structure has the disadvantage that it takes a huge amount of time to record a large amount of documents and the like.

[Summary of the Invention] Therefore, the present invention has been made based on the above-mentioned drawbacks, and it is possible to perform high-quality color recording and to record at a higher speed in monochrome recording than in color recording. The purpose of the present invention is to provide a color inkjet recording device that is easy to use.

In order to achieve the above object, the present invention provides an inkjet recording head equipped with nozzle sections arranged in color order to eject ink of three primary colors, black, and a color obtained by mixing the three primary colors in the direction in which a recording medium is transported; In a color inkjet recording device, the inkjet recording head has a moving mechanism that sequentially moves the recording medium in the transport direction in correspondence with the nozzle portions of each color, and the inkjet recording head has the number of nozzles in the nozzle portion that ejects black ink compared to the number of nozzles in the nozzle portion for other colors. The number of nozzles is greater than the number of nozzles in the nozzle section for ejecting ink, and the nozzles for ejecting the black ink are arranged at intervals of an integral multiple of the dot pitch in the moving direction of the inkjet recording head.

The present invention is capable of achieving high-speed recording of only black ink images, which has not been recognized in the past, at a higher level than recording using an inkjet recording head configured with the same number of nozzles for each color of multiple ink colors. It also has the following advantages: it is compact and can provide excellent image quality.

[Examples] The present invention will be described in detail below based on examples shown in the drawings.

3 and 4 show embodiments of the present invention. Third
In the figure, seven color ejection systems are provided: black (B), cyan (C), magenta (M), yellow (Y), green (G), red (R), and blue (BL). The ejection timing of each of the seven color ejection systems is controlled by an arithmetic unit 4 via a driver 3 in accordance with a printing command Pr from the outside. Then, there are more nozzles 2 for black (B) than nozzles for other colors (here, two), and in order to supply ink to these two nozzles, one ink supply pipe 7 is provided for each. It is provided.

Here, the nozzles 2 are arranged vertically and parallel to the transport direction of the recording medium 1 for each dot line, and a recording head equipped with these nozzles reciprocates over the recording medium 1 in a direction perpendicular to the transport direction of the recording medium. Recording is done by exercising. However, since only one color can be recorded per line in one-way movement, it goes without saying that the recording medium 1 is transferred line by line and recording is performed in accordance with the ejection timing generated by the arithmetic unit 4.

Then, these eight nozzles 2 are connected to a nozzle array 8.
Figure 4 shows the state in which it is installed.

In FIG. 4, two nozzle injection holes 9 for black are provided spaced apart by an integral multiple α of the dot pitch in the moving direction of the array (indicated by arrow T in the figure).

However, here, the reference numeral 9' indicates the injection holes of the nozzles of the other six colors.

By adopting such a configuration, in addition to the above-mentioned effects, it is possible to record documents, etc.
If only black is expected to be used frequently, the recording speed in the direction of movement of the array can be doubled by ejecting ink from the two black nozzles 2 at the same time.

In the above embodiment, the driver 3 and ink supply pipe 7 are provided independently for each nozzle, but it is also possible to share one driver and ink supply pipe for nozzles of the same color. Of course.

[Effects] As is clear from the above description, according to the present invention, nozzle portions are provided in color order to eject ink of three primary colors, black, and a color obtained by mixing the three primary colors in the direction in which the recording medium is transported. In the color inkjet recording apparatus, the inkjet recording head has a moving mechanism that sequentially moves the recording medium in the transport direction in correspondence with the nozzle sections of each color. The number of nozzles is greater than the number of nozzles in the nozzle section that ejects ink of other colors, and the nozzles that eject the black ink are arranged at intervals of an integral multiple of the dot pitch in the moving direction of the inkjet recording head. By doing so, it is possible to provide a color inkjet recording apparatus that can perform high-quality color recording and can perform monochrome recording at a higher speed than color recording.

[Brief explanation of the drawing]

1 and 2 are schematic configuration diagrams of a conventional color inkjet recording device, FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 4 is a front view of the nozzle array portion of FIG. 3. be. Explanation of symbols, 1...Recording medium, 2...Nozzle,
3... Driver, 4... Arithmetic device, 6... Ink tank, 7... Ink supply pipe, 8... Nozzle array.

Claims (1)

[Scope of Claims] 1. An inkjet recording head equipped with nozzle portions arranged in color order to eject ink of three primary colors, black, and a color obtained by mixing the three primary colors in the direction in which the recording medium is transported; In a color inkjet recording device, the inkjet recording head has a moving mechanism that sequentially moves in a transport direction in correspondence with a nozzle section, wherein the inkjet recording head has a number of nozzles in a nozzle section that ejects black ink, and a number of nozzles in the nozzle section that ejects ink of other colors. 1. A color inkjet recording apparatus, characterized in that the number of nozzles for ejecting the black ink is greater than the number of nozzles in the color inkjet recording head, and the nozzles for ejecting the black ink are provided at intervals of an integral multiple of the dot pitch in the moving direction of the inkjet recording head.