JPH02235761A - Method for cleaning ink jet head - Google Patents

Abstract

PURPOSE:To certainly clean the front surface of an ink jet head by impregnating a cleaning blade with an alcohol solution to set the same to a wet state and specifying the relative moving speed of the cleaning blade and the ink jet head. CONSTITUTION:A cleaning blade 31 shaped into a porous structure is immersed, for example, in a solution, which is prepared from 60-70wt.% of a high viscosity alcohol hard to evaporate such as glycorine, 10-20wt.% of low viscosity alcohol such as ethanol and the remainder of water, for about 5 min to be impregnated with said solution. Next, a carriage is moved to slide the cleaning blade 31 with an ink jet head 50 to clean said ink jet head 50 and, at this time, when the relative speed of the ink jet head 50 and the cleaning blade 31 is set to 5.0mm/sec or less, the effect of the capillary phenomenon of the cleaning blade is sufficiently obtained to perform cleaning certainly.

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an ink jet head of an ink jet printer,
In particular, this is an ink jet head cleaning method that cleans the periphery of the orifice that jets the ink droplets. (Explanation) Conventional technology An inkjet printer rotates a drum wrapped around recording paper at high speed, and multiple ink jet heads are arranged on a carriage arranged around this drum, and each ink jet head records ink. The inks are sprayed onto paper to create a monochromatic image or a color image by mixing inks with each other. By the way, for example, in a so-called on-demand type ink ejection head that ejects ink droplets by applying a weak pressure change to an ink reservoir, there is a distance of only a few meters at most between the ink droplet and the recording paper, and the ink Droplets bounce off the recording paper and solidify on the front surface of the ink jet head, and often attract fibers and dust from the recording paper, resulting in clogging of the jet nozzle. Fig. 5 is a schematic diagram of an inkjet printer using a conventional device, in which a carriage arm (3) pivotally supported on a slider shaft (3) faces a recording paper (2) wound around a rotating drum (1). 4) an ink jet head (5a);
<5b), (5C), and (5d) are arranged, and each ink jet head (5
Ink droplets are ejected from a), (5b), (5C), and (5d) to print on recording paper (2). At one end of the rotating drum (1) are pads (6a), (6b), (6C) on which the ink jet heads (5a), (5b), (5C), (5d) are placed after printing is completed. , (6d) are disposed, and each ink jet head (5a), (5b), (
5C) and (5d) are moved by a carriage arm (4) between a print position facing the rotating drum (1) and a home position facing each of the pads (6a) to (6d). ．． And one end of the rotating drum (1) and the pad (6a>~
Cleaning equipment between <6d>! (30) is installed. The cleaning device (30) accommodates a cleaning liquid in a cleaning bowl formed in an inverted U shape, and a cleaning blade (31a) made of polyurethane or the like with its lower end immersed in the cleaning liquid.
)(3lb>(31c) The upper end of (31d) is made to protrude from above the cleaning tank, and the ink jet heads (5a) to (3lb) between the home position and the print position are
5d), facing the movement area of the ink jet head (5a) ~
There is a device that removes dust and the like by bringing the front surface of the cleaning device (5d) into sliding contact with the cleaning device (32) while the device (5d) moves between the two positions. For example, Utsukaisei 58-128
Details in Publication No. 034. However, the above-mentioned apparatus requires a cleaning bowl for supplying the cleaning liquid to the cleaning blade (31g), and therefore cannot be made smaller. Therefore, as shown in Japanese Patent Application No. 62-294943, a cleaning device that does not require a cleaning tank is created by immersing the cleaning blade in an alcohol solution and setting it in a wet state. Proposed. (c) Problems to be solved by the invention As mentioned above, in inkjet printers,
It is necessary to keep the ink ejecting head's orifice and its surroundings clean at all times. That is, if dust or excess ink adheres to the rift, even if no clogging occurs, it will affect ink ejection and deteriorate printing quality.
Particularly in the case of Color Bunonta, this appears as a color shift. By the way, when cleaning is performed using the cleaning blade described above, there are cases where deposits are left behind on the front surface of the ink jet head. After extensive study, the inventors of the present invention found that the relative speed between the cleaning blade and the ink jet head affects the cleaning state of the ink jet head. In other words, when we analyzed the causes of unwiped areas, we found the following. The frictional force between the head and cleaning blade and the capillary action of the cleaning blade cannot be utilized, resulting in unwiped residue. Furthermore, when the viscosity of the same ink increases due to temperature changes, the force of adhesion to the nozzle surface increases, resulting in unwiped residue. The present invention is based on this knowledge and provides a cleaning method that reliably cleans the front surface of an ink jet head. (2) Means for Solving the Problems The present invention moves an inkjet head relative to a cleaning blade made of a porous structure, brings the cleaning blade into sliding contact with the inkjet head, and cleans the orifice of the inkjet head. A method of cleaning an ink jet head by wiping its surroundings, the cleaning blade being impregnated with an alcohol solution and set in a wet state, and the relative movement speed between the cleaning blade and the ink jet head being 5.0 m/sec or less. It is characterized by being set to . (E) Function When the relative movement speed between the cleaning blade and the ink jet head is set to 5.0 mm/sec or less, the effect of the capillary phenomenon of the noning blade can be sufficiently obtained, and cleaning can be performed reliably. (F) Example Hereinafter, an example of the present invention will be explained with reference to FIGS. 1 to 4. First, an ink jet head to which the present invention can be applied will be explained with reference to FIG. FIG. 3 is a schematic cross-sectional view showing the ink jet head of an airflow type ink jet printer. This shows the recording paper that arrived. The ink jet head (50) has a head main body (51) in the shape of a thick disk, and a diaphragm (52) on the rear side.
It is closed at a), and the front side is a diaphragm plate (52c).
The pressure chamber (52) closed at
The ink is completely formed around the outer periphery and the front of the ink, and the front side is closed by an ink nozzle plate (53b) equipped with an orifice (53a)! (53), and an air chamber (54b) closed by an air nozzle plate (54b) formed over the outer periphery and front of this ink chamber (53), and equipped with an air nozzle (54a) at a position where the front side faces the inner orifice (53a). 5
4). The pressure chamber (52) is filled with ink, and the ink chamber (53) is connected to an ink cartridge (not shown) via an ink tube (53d), and is filled with the ink that can be supplied from there, and is further filled with air. The chamber (54) has an air tube (54
d) is connected to an air pump (not shown).

When an electric signal is applied to the diaphragm (52a), the diaphragm (52a)
The vibration of a) is propagated to the diaphragm plate (52c) using the ink in the pressure chamber (52) as a pressure propagation medium, and the vibration of the diaphragm plate (52c) is propagated to the ink in the ink chamber (53) as a pressure wave, This ink is ejected as ink droplets from the air chamber (54).
Recording is performed by blowing the air onto the recording tank 61) together with the air flow ejected from the air nozzle (54a). On the other hand, when the orifice (53a) is not in use, even if the orifice (53a) becomes clogged due to dryness or is subjected to mechanical impact, the orifice (53a)
In order to eliminate the problem of air being sucked into the ink chamber (53) through a), a pad is applied to the air nozzle (54a) to close it, while the control valve is closed to open the air chamber (54). It is opened to the atmosphere and the diaphragm (52a
), the air chamber (54) is supplied with ink from the air rifice (53a), and the metal body inside the air chamber (54) is filled with ink while the air in the air chamber (54) is released into the atmosphere. ing. When reusing, the pad is removed, the air pump is driven, the control valve is opened, pressurized air is supplied into the air chamber (54) through the air tube (54b), and the ink in the air chamber (54) is discharged. , After that, printing begins as shown in Figure 3. Next, the cleaning device applied to the present invention will be explained with reference to FIGS. 1 and 2. Figure 1 is a perspective view of the cleaning device, and Figure 2 is a longitudinal sectional view. As is clear from the figure, the cleaning device (30) of the present invention includes each ink droplet ejecting device (5g) (5b
) (5c) Four contact parts (31a) (3lb>(31
c) (31d) and the corresponding contact parts (31a) (3lb) (3
1c) (31d>)
32) and a cleaning blade (31). The cleaning blade (31) is an integrally molded porous structure made of urethane foam or the like.
The support part (32) of this cleaning blade (31) is held on the arch-shaped holding body (35) with pins (36) (36). Then, use the above-mentioned cleaning blade (31
) is pre-impregnated with a cleaning solution that does not easily evaporate and is set to a wet state. In other words, a highly viscous alcohol that is difficult to evaporate, such as glycerin, is
A cleaning blade (31) in which a porous structure has been formed is added to a solution prepared in the range of 0 to 70% by weight, 10 to 20% by weight of a low-viscosity alcohol such as ethanol, and the remainder being water. The cleaning blade (31) is impregnated with the solution by dipping for a minute.Next, the carriage is moved and the above-mentioned cleaning blade (31) and ink jet head (50) are brought into sliding contact for cleaning. Tables 1 and 4 show the results of an experiment on cleaning the ink jet head (50) by allowing various changes in the moving speed of the carriage, that is, the relative speed between the ink jet head (50) and the cleaning blade (31). As shown in the figure.The things that have a negative impact on print quality are:
Since this is a case where ink remained on the circumference of the air nozzle (54a) of the ink jet head (50), the amount of ink remaining on the entire circumference was taken as 100%, and the amount of unwiped residue was measured. After cleaning was performed at various temperatures of 15°C, 25°C, and 35°C while varying the relative movement speed, measurements were performed. The viscosity of ink has a characteristic that the lower the temperature, the higher the viscosity, and at 35°C it is 6, Ocp,
It is 8.5 cp at 15°C. As is clear from Table 1 and Figure 4, printing is normally carried out with the area around the ink jetting head (50) maintained at around 30°C, so the relative movement speed must be 5.011111/sec or less. It can be seen that when the setting is set to , there is no leftover wiping under normal operating conditions, and reliable cleaning can be performed.Furthermore, when the relative movement speed is 3.3 mm/sec or less, there is no leftover wiping at all at each temperature.

<<G>> Effects of the Invention As explained above, according to the cleaning method of the present invention, ink can be reliably removed without leaving any ink on the ejection surface of the ink ejection head, making it possible to continuously perform good printing. can.

[Brief explanation of the drawing]

1 and 2 show a cleaning device used in the present invention, with FIG. 1 being a perspective view and FIG. 2 being a sectional view. FIG. 3 is a schematic sectional view showing the ink jet head, FIG. 4 is a measurement diagram showing the relative movement speed and cleaning state at each ink temperature, and FIG. 5 is a perspective view showing the ink jet printer. 31, 31a to 31d...Cleaning blade, 5
0, 5a to 5d... Ink jet head, 53... Orifice 54a... Air nozzle. Figure 4). , Dori special axis A (m hit S)

Claims (1)

[Claims] (1) moving a cleaning blade made of a porous structure relative to the ink jetting head, and slidingly contacting the cleaning blade with the ink jetting head;
A method for cleaning an ink jet head that wipes an orifice of the ink jet head and its surroundings, the cleaning blade being impregnated with an alcohol solution and set in a wet state, and the relative movement speed between the cleaning blade and the ink jet head being A method for cleaning an ink jet head, characterized in that the speed is set to 5.0 mm/sec or less.