JPS59209877A - Color ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent printing in a mixed color from occurring at the start of printing and enable to perform color dot printing with high quality, by a method wherein a printing action of each ink is performed in the direction toward a waste ink sump for a predetermined period of time. CONSTITUTION:After a predetermined period of time from the end of purging, a pump in an ink-supplying system ISS is not driven, while a head 1 drives piezoelectric converting elements 4 at, for example, a maximum frequency suitable for printing, in response to a command from a CPU, whereby all channels are simultaneously operated to jet inks continuously toward the waste ink sump 8. By this, mixed inks remaining in the nozzles 2 are completely discharged into the sump 8, and only the inks of pure colors are left in the nozzles 2. The waste ink sump 8 is provided, for example, along the moving direction of the head 1 between a printing region and a purging position. When a period of time sufficient for completely removing the mixed inks from the ink nozzles is passed, the continuous jetting is stopped by a command from the CPU. Thereafter, the head 1 leaves the position faced to the sump 8, is moved to a predetermined position faced to a recording paper, and after a predetermined time point, normal printing can be started.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color inkjet recording device, and in particular, one recording head is provided with color nozzles for two or more colors in close proximity, and ink is ejected from these thin nozzles. This invention relates to a color inkjet recording apparatus that records colored characters, figures, etc. on a recording medium such as paper by ejecting and flying small droplets.

In order to draw high-quality characters, figures, etc. on recording paper using a conventional color inkjet recording apparatus, fine ink droplets of equal diameter must be ejected regularly and intermittently. In order for such ink droplets to fly smoothly and to stably draw characters and figures on recording paper, the properties of the ink itself must be sufficiently uniform and stable. At the same time, it is necessary to prevent air bubbles from entering the ink flow path from the ink tank to the recording head.

In addition, drying of the ink in the nozzle, dust, paper powder, etc. can cause solidified matter in the ink, which often causes clogging. For this reason, ink may not be ejected or ejected unstablely, and ejection accuracy such as ejection efficiency, stability of ink droplet formation, and responsiveness may deteriorate, so it is necessary to remove these impurities as described above.

As described above, in an inkjet recording apparatus, it is an essential condition to completely remove air bubbles and solid matter generated or mixed in the ink flow path.

Many proposals have been made regarding a purge operation for removing (purging) air bubbles and foreign matter from the nozzles or other ink flow paths in the recording head. For example, Japanese Patent Application No. 57-156085 proposed by the present applicant also relates to this purge operation, and in an inkjet recording apparatus, for example, when the power is turned on, pressurized ink is flowed into the ink flow path or nozzle part, and the purge operation is performed. When the operation is performed, air bubbles and foreign matter inside the nozzle and recording head are discharged to the outside of the nozzle along with overflowing ink, and cleaning is performed.

In a color inkjet recording device, when two or more color nozzles are installed in the same recording head and the tip surfaces of the different color nozzles are close to each other, the different color inks overflowing onto the nozzle surface will mix. , it flows back into the nozzle due to surface tension, and for a while after the purge operation,
Inks of mixed colors are ejected, and ink of the original color cannot be ejected, making it impossible to print in a desired color on a recording medium such as paper.

Figure 1 shows an outline of a color inkjet recording device, and Figure 1(a) shows an example of an enlarged nozzle surface.The magenta and yellow inkjet heads will be explained below. . FIG. 1(b) shows a schematic configuration diagram. Although magenta and yellow nozzles are lined up on the front and back sides of one recording head 10, only the magenta color on the front side will be described here. On the nozzle surface 3, 12 magenta nozzles 2 (M) and 12 yellow nozzles 2 (Y) are arranged side by side. Each nozzle 2 is connected to a common ink chamber 5. A piezoelectric transducer element 4 is provided in the middle of the nozzle 2, separated by a wall for each nozzle. Furthermore, the magenta common ink chambers 5 are connected to an ink supply system ISS K via tubes 6 which are ink flow paths.

The common ink chamber 5 is always in a full state, and by applying a pulse signal to the piezoelectric transducer 4, an ink drop about the same diameter as the ink door is ejected from the tip of the nozzle 2 to draw characters and figures on the recording paper. Also, during purging, the pump of the ink supply system ISS is driven to pump ink into the head 1. The pumped ink overflows from the nozzle surface 3, and magenta and yellow colors are mixed on the nozzle surface.

Therefore, when printing is performed by scanning from left to right on the recording paper 11 after purging, for example, if the printing operation is performed while moving the print head 1 to the right with respect to the recording paper 11 as shown in FIG. Even if you try to print all the dots, the first few dozen characters will be printed in part 12A (one extra line) using cloudy red ink that is a mixture of yellow and magenta, and then the original color of yellow will be printed. This may cause problems such as parts printed with ink.

Purpose of the Invention The present invention provides a multi-nozzle head that can print in multiple colors, and when the nozzle surface is wetted, especially during a purge operation, multiple colors of ink overflow onto the nozzle surface mix and mix. Eliminates the problem that due to backflow into the color nozzle, a cloudy color ink that is different from the original color is ejected during printing for a while after that, making it impossible to reproduce the desired color on the recording medium. The purpose is to

Structure of the Invention The present invention is a color inkjet recording device in which nozzles are arranged close to each other and can print two or more colors, so that the printing operation of four inks is performed toward a waste ink reservoir for a certain period of time. This is achieved by a color inkjet recording device characterized by the following.

The present invention is particularly advantageous in that, after a purge operation, the cloudy ink in the nozzle is discharged by ejecting continuous jets toward a target other than the recording medium, so that the nozzle is filled with ink of the original color. This allows you to start normal printing after setting the

Embodiment FIG. 3 shows the configuration of a color inkjet recording apparatus of the present invention. The figure shows a single color, but a multicolor color has the same configuration as shown in the figure from four CPUs for each color in parallel. ing. FIG. 4 shows a time chart of the recording apparatus shown in FIG.

First, a barge operation is performed from time t1 to time t.

Purge is activated when the power is turned on or when a channel miss occurs. A purge command from the CPU is amplified by an amplifier, and, for example, the pump 7 of the magenta and yellow ink supply system (I8B) is driven, and ink of the same color is force-fed into each head 1 and overflows from the nozzle surface 3.

At time t, the drive of the pump 7 is stopped, and the overflow of ink from the nozzle 3 is also stopped. Subsequently, the ink within the head 1 returns from the pressurized state to the original ambient atmospheric pressure. Here, the ink that overflows onto the nozzle surface 3 and adheres to the nozzle surface 3 and remains is not only mixed with each color on the nozzle surface 3, but also flows back into the two nozzles 2.

After some time has passed, some of the ink left on the nozzle surface 3 is wiped off by the cleaning means, but some of it flows back into the nozzle 2 and the inside of the head 1 returns to its original atmospheric pressure, reducing the pressure. becomes stable and ready to start printing. However, if printing is started at this point, since turbid ink remains in the nozzle 2, printing will be performed in a color different from the desired color for a while, as shown in FIG.

Here, in the present invention, after a certain period of time t after the end of purge.

At this point, the ink supply system ISS pump is not driven and the CPU
In response to a command from , the head 1 drives the piezoelectric transducer 4 at the highest printable frequency, for example, and starts continuous ejection (continuous printing operation) toward the waste ink reservoir 8 on all channels simultaneously. As a result, all the cloudy ink in the nozzle 2 is discharged to the waste ink reservoir 8, and only the original pure color ink remains in the nozzle 2. Here, the waste tank 8 is provided, for example, along the moving direction of the head l, between the printing area (the area facing the recording paper) and the position where the purging is performed. At time t4, when sufficient time has elapsed for the mixed color ink to be removed from the ink nozzle, continuous ejection is stopped by a command from the CPU.

Thereafter, the head lid leaves the position facing the waste ink reservoir 8 and moves to a predetermined position facing the recording paper, and from time t onward, normal printing can begin.

The present invention described above is a technical means to prevent the turbid color of ink that occurs on the nozzle surface, so the nozzle position is located above the nozzle surface, so that there is a channel that does not cause backflow of turbid ink at the nozzle. If so, that channel does not need continuous injection.

In addition to the above-mentioned barge operation, for example, after replacing an ink cartridge, after the device receives a shock and ink overflows from the nozzle, and the overflowing ink flows back into the nozzle, or after the cleaning means Of course, the above-described continuous ejection may be performed after the head surface has been cleaned by cleaning the head surface, so that the cloudy ink in the nozzle can be completely discharged.

In addition, when continuous ejection is performed, the waste ink reservoir may be any device that collects unnecessary ink, such as a cap roller or waste ink collection drain, and if the head moves to the previous position and performs ejection, There is no need to newly install a separate collection waste ink reservoir.

Since the purpose of continuous ejection described above is to discharge cloudy ink, it is most effective to eject continuously by applying a pulse of the highest frequency to a piezoelectric transducer such as a piezo element, but it is not limited to this. The injection may be intermittent, and it is not necessary to inject all channels at the same time.

Effects of the Invention Conventionally, in color inkjet recording devices, printing was often done in a cloudy color unintentionally at the start of printing, but the present invention makes it possible to print extremely high-quality color tod prints.

[Brief explanation of the drawing]

Figure 1 shows an outline of a color inkjet recording device, with Figure 1(a) showing the nozzle surface and Figure 1(b) showing the nozzle surface.
shows a schematic configuration diagram.・Figure 3 shows the present invention l...
...Recording head 2.2 ((B), 2(Y)...Nozzle 3...
・°・Nozzle surface 4...Piezoelectric conversion element 5
...Common ink room 6...Tube 7...Pump 8...Waste ink reservoir agent Yoshimisuji Kuwabara Figure 2 U4 Figure Tokiga-11

Claims (3)

[Claims] (1) In a color inkjet recording device in which nozzles are arranged closely and can print two or more colors,
A color inkjet recording device characterized in that ink is printed toward a waste ink reservoir for a certain period of time. (2) A color inkjet recording apparatus according to claim 1, wherein the printing operation is performed after a purge operation. (3) The color inkjet recording apparatus according to claim 1 or 2, wherein the printing operation is performed continuously.