JPS6334832B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention generally involves ejecting a recording liquid called ink as small droplets from an orifice (discharge port) and causing the droplets to adhere to a recording surface. The present invention relates to a cleaning method for an inkjet recording apparatus that performs recording using an inkjet recording apparatus.

[Conventional technology]

Among the various recording methods currently known, it is a non-impact recording method that generates almost no noise during recording, is capable of high-speed recording, and does not require special fixing treatment on plain paper. The so-called inkjet recording method (liquid jet recording method), which allows recording to be carried out over a long period of time, is recognized as an extremely useful recording method. Various methods have been proposed for this inkjet recording method, some have been improved and commercialized, and others are still being worked on to put them into practical use. be.

In short, the inkjet recording method involves flying droplets of a recording medium called ink.
Recording is performed by attaching it to a recording member such as paper. The inkjet recording method is roughly divided into several types based on the method of generating recording liquid droplets and the control method for controlling the flying direction of the generated droplets.

Among them, one of the representative methods is, for example
UPS3596275 (Sweet method), USP3298030 (Lewis
and Brown method), etc., in which a droplet flow with a controlled amount of charge is generated by a continuous vibration generation method, and this droplet flow with a controlled amount of charge is uniformly distributed. By causing the droplet to fly between deflection electrodes to which an electric field is applied, recording is performed on the recording member while controlling the flying trajectory of the droplet. This method is also generally referred to as a continuous method.

Other typical methods that can be compared with this are, for example,
This is the method (Stemme method) disclosed in USP3747120. In this method, an electrical recording signal is applied to a piezo vibrating element attached to a recording head that has an orifice for ejecting liquid for recording, and this electrical recording signal is applied to the mechanical vibration of the piezo vibrating element. Recording is performed by ejecting droplets from the orifice and adhering them to the recording member whenever necessary according to the mechanical vibration. This is the so-called on-demand method.

[Problems to be solved by the invention]

As for the inkjet recording technology outlined above, several disadvantages have been pointed out in the past in putting it into practical use. Among them, the major drawback is that the ink ejection orifice of inkjet recording is extremely fine (approximately 5 μmφ to 200 μmφ).
Therefore, the ejection orifice becomes clogged due to ink drying while the recording operation is stopped. In this case, recording becomes impossible unless the clogging is cleared.

Therefore, various clogging prevention measures have been proposed.

One such method is to fill an ink flow path provided in a recording head with a liquid called clear ink, which does not contain a coloring agent and is only a solvent, and then leaves the liquid at rest. However, this method requires
The disadvantages are that recording cannot be started immediately because the recording head is already filled with clear ink, and that the clear ink and ink mix at the beginning of ejection, resulting in a decrease in the density of the ink.

Another method is to cover the tip of the recording head with a cap to seal the ejection port including the peripheral area. However, with this method, ink stains may remain around the ejection port, dust may adhere, etc.
There was a drawback that the discharge port could be damaged. In addition, when a so-called multi-use system in which a plurality of discharge ports are provided, there is a problem in that it takes too much time and effort.

Further, for example, Japanese Patent Application Laid-open No. 78135/1983 describes that during non-recording operations, ink in the ink-filled area is caused to flow out and air is introduced from the ejection nozzle into the ink-filled area.

Japanese Patent Application Laid-Open No. 53-97429 describes filling the recording head with a cleaning liquid that does not mix with the recording liquid when starting up the recording apparatus.

Japanese Patent Publication No. 44-4517 describes that when the recording apparatus is stopped and not used for a certain period of time, ink is removed from the nozzles of the recording apparatus using cleaning water.

Japanese Utility Model Publication No. 53-29737 describes that when a recording operation is stopped and a nozzle cleaning operation is performed, a cleaning liquid is ejected from the nozzle instead of ink.

However, the technical content described in any of the above-mentioned publications does not allow for an immediate transition from a cleaning operation to a high-quality recording operation with stable density because the ink and the cleaning liquid do not mix. However, it has not been possible to fully meet the technical demand for cleaning methods for inkjet recording apparatuses, which requires a greater degree of freedom in the selection of materials.

[Means for solving problems]

Therefore, in the present invention, by eliminating the drawbacks seen in the prior art, it is possible to completely prevent clogging of the ejection ports and ink flow paths during a printing pause, and to keep the surrounding area clean so that good printing can always be performed immediately. The main objective is to provide a novel cleaning method for an inkjet recording device that can be carried out well and stably.

To achieve this object, the present invention provides a cleaning method for an inkjet recording apparatus that performs recording by discharging a part of the ink in an ink path in a recording head from an ejection port communicating with the ink path. a step of emptying the ink path by discharging ink supplied from a tank from the ejection port, a step of supplying a cleaning solvent from a cleaning solvent tank to the empty ink path, and a step of supplying a cleaning solvent to the empty ink path; A cleaning method for an inkjet recording apparatus, comprising the step of discharging the filled cleaning solvent from the ejection port to empty the ink path again.

〔Example〕

In the present invention, after recording is completed, first, the supply of ink to the ink flow path in the recording head is cut off, and then clean air is passed through the flow path to remove the ink in the ink flow path to the outside of the head. put out. The ink that has come out of the head is sucked up by a suction device provided as necessary, and then returned to the ink tank. Next, a cleaning solvent made of, for example, a solvent containing an ink solvent component is flowed into the ink flow path, and this is also brought out of the head and sucked up by a suction device. After that,
Flow clean air into the ink flow path of the head again.
The cleaning solvent present in the ink flow path is substantially completely drained out of the ink flow path. In this manner, by cleaning and emptying the ink flow path of the recording head, the liquid jet recording apparatus is put into a rest state.

Then, when printing is restarted, it is only necessary to fill the ink flow path of the printing head with ink from the ink tank, so that stable printing can be performed at the same time as printing is restarted, and the concentration of the ink used remains unchanged. In addition, when recording is paused, there is no ink in the ink flow path in the head, so the area around the ejection port does not get wet and dust or ink dries around the ejection port, which causes unstable printing. Since solidification of the coloring agent is prevented, good ejection can be performed at any time with good immediacy. In addition, it is sufficient to supply ink, cleaning solvent, and air into the ink flow path of the recording head at approximately the same pressure (positive pressure), and in addition, when flowing these out of the ink flow path, the ejection port Since it allows more outflow, there is no possibility of inhaling dust from the atmosphere through the discharge port. In addition, since the cap is not mechanically covered, there are various problems that may occur when the cap is covered, such as dust from the cap (mainly dried colorant, etc.), scratches and defects around the discharge port due to cap collisions, etc. , completely eliminated, and in this respect as well, stable ink droplets can be ejected and a good recorded image can be obtained.

Embodiments of the present invention will be described in detail below with reference to the illustrated examples.

Example 1 Inkjet recording was carried out as described below using a recording head having a cylindrical electromechanical transducer 1 shown in FIG. The recording head shown in FIG. 1 consists of a tapered glass cylinder 3 (inner diameter 500 μmφ, outer diameter 700 μmφ, length 20 mm) with a discharge port 2 (50 μmφ) at the tip, a cylindrical electromechanical transducer 1 (made of PZT ceramics) , inner diameter 720μmφ, outer diameter 920μmφ,
length 13mm), electrodes 4, 5, conductive layers 6, 7, ink supply tube 8 (PVC tube, inner diameter 600μmφ, thickness
200μmφ). Note that the glass cylinder 3 and the electromechanical transducer 1 are bonded together using a modified epoxy adhesive. 1kHz to 10k for electrodes 4 and 5
By passing the Hz pulse, the electromechanical transducer 1 expands and contracts, and the ink that had filled the ink flow path 9 is ejected from the ejection port 2 and turns into droplets 10 toward the recording member 11. A cleaning method for an inkjet recording apparatus that carries out recording by mounting this type of recording head will be explained with reference to the system diagram shown in FIG. During recording, first, the pump 12 is started, the valves 14 and 15 are opened, and pressure is applied to the ink in the ink flow path in the recording head section 22 from the discharge port 2 shown in FIG. 1 to the extent that no ink is discharged. give it. The apparatus also includes an ink tank 13, valves 14 and 15, filters 16, 17, 18, 19, a cleaning solvent tank 20, and a drive circuit section 21 for driving a recording head section 22.

The details of the recording head constituting the head section 22 are as follows.
As shown in FIG. A droplet 23 ejected in response to an input signal input to the head section 22 flies toward a recording member 24, and recording is performed.

When recording is completed, the valves 14 and 15 on both sides of the ink tank 13 are closed, and the valve of the cleaning solvent tank 20 is opened to supply cleaning solvent into the ink flow path of the head section 22. Next, the valve of the cleaning solvent tank 20 is closed, and the valve 14 is opened to pass clean air that has been cleaned by the filter into the ink flow path of the head section 22.
Open 15. After the cleaning solvent has been substantially completely removed by clean air, close all valves. In this way, the ink flow path of the head section 22 is emptied, and the liquid jet recording apparatus is put into a rest state or a storage state.

If you pause the recording operation or save the liquid jet recording device as described above, when you resume recording,
Printing can be done immediately, and the resulting image quality is extremely good. Incidentally, the ink and cleaning solvent used in this example were as follows.

Ink composition: Distilled water, diethylene glycol, black dye, 60 parts, 35 parts, 5 parts (manufactured by Mitsubishi Kasei, Direct Fast Black B) Cleaning solvent: Distilled water, methanol, 50 parts, 50 parts Example 2 The parts shown in Figure 3 a, b, and c were By joining and assembling, a head having multiple discharge ports as shown in FIG. 4 was created.

In Fig. 3a, 25 is a common ink block, and 26 is a 1 mm thick glass plate with a width of 100 μm and a depth of 100 μm.
This is a grooved lid with grooves cut at a pitch of 250μ for passing 100μ ink. Further, 27 is an ink introduction tube.

The part shown in FIG. 3b is made in substantially the same manner as a conventional thermal heater. Incidentally, 2
8 is an alumina substrate with a thickness of O'7 mm, on which is a SiO film with a thickness of 4 μm, hafnium boride with a thickness of O'05 μm, aluminum with a thickness of 700 μm, and aluminum with a thickness of 1 μm.
SiO films are formed in this order by sputtering, vapor deposition, etc., and further, the common electrode section 29, individual electrode section 31, and heating element section 30 are formed using an etching technique. The size of the heating element 30 is
The size is 250μm×100μm, and the individual electrode pitch is 250μm. FIG. 3c shows an unnecessary ink absorbing section, which consists of a absorbing block 33 in which a 50 μm slit 32 is formed and a absorbing tube 34. The recording operation is illustrated in FIG.

FIG. 5 is a system diagram of this embodiment.

35 is the multi-nozzle head obtained as described above, 36 is a suction part, and 37 is a suction pump for suction. In addition to this, this recording apparatus also includes a pump 38, an ink tank 39, a cleaning solvent tank 40, and on/off valves 41 and 4 similar to those shown in the first embodiment.
2, filters 43, 44, 45, 46, and a drive circuit section 47. With this device, using ink with the following composition (pressure conditions: 0.4Kg/cm ² ),
Ink was ejected at a frequency of 5kHz.

Ink composition: Isopropanol diethylene glycol black dye 67 parts 30 parts 3 parts (Spiron Black MH Special manufactured by Hodogaya Chemical Industry Co., Ltd.) The ink pushed out of the head 35 by pressure is absorbed by the absorption part 36. Printing is performed when ink droplets 48 ejected in response to a signal adhere to a recording material 49.

After printing is completed, the valve opening and closing operations are performed in the same manner as in the first embodiment, and during the pause, the ink flow path of the head 35 is emptied and there is substantially no ink. Therefore, even if left for a long period of time, there will be no clogging due to ink drying. Furthermore, since the ink is introduced into the ink head 35 immediately after the printing operation is resumed, its rise is extremely quick.

The embodiment shown in FIG. 5 above can be modified as in the embodiment shown in FIG. 6 below. In the embodiment shown in FIG. 6, a recovered ink circulation system is added to the embodiment shown in FIG. Others 5th
Elements that are equivalent to those shown in the figures are given the same reference numerals. The ink pushed out of the head 35 by pressure or the like is absorbed by a suction section 36. This ink passes through the suction pump 37 again and passes through the conduit 5.
0 to the ink tank 39. Note that an on-off valve 51 is provided on the outlet side of the suction pump 37, and when the cleaning solvent is sucked out, the opening to the conduit 50 is closed and the cleaning solvent is discharged into a container outside the ink flow path of the recording head. do.

Incidentally, 52 is an on-off valve, and 53 is a filter. In this manner, unnecessary ink leaking from the head 35 due to pressurization or the like during a recording operation is recirculated and the ink is reused.

It goes without saying that in the embodiment shown in FIG. 5, when the recording operation is stopped, almost the same operation as in the embodiment shown in FIG. 5 is performed. .

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a cleaning method for an inkjet recording apparatus that always performs stable ink ejection, enables quick start of recording, and performs high-quality recording.

In particular, in the present invention, since the ink and cleaning liquid do not mix, it is possible to immediately shift from a cleaning operation to a high-quality recording operation with stable density, and moreover, there is a high degree of freedom in selecting materials for the ink and cleaning liquid. This method can fully meet the demand for cleaning methods for inkjet recording apparatuses, such as a method for cleaning inkjet recording apparatuses.

[Brief explanation of the drawing]

Figure 1, Figure 3a, Figure 3b, Figure 3c, Figure 4
The figure is a schematic diagram for explaining the details of the inkjet recording head used in the present invention.
5 and 6 are recording system diagrams for explaining embodiments of the present invention, respectively. In the figure, 2 is a discharge port, 13 and 39 are ink tanks, 20 and 40 are cleaning solvent tanks, and 22 and 35 are
is an inkjet recording head, 21 and 47 are drive circuit sections, 12 and 38 are pumps, and 14 and 1 are
5, 41, 42, 51, 52 are on-off valves, 23, 4
8 is an ink droplet, 11, 24, 49 are recording materials, 3
6 is a suction part, and 37 is a suction pump.

Claims (1)

[Claims] 1. In a cleaning method for an inkjet recording device that performs recording by discharging a part of the ink in an ink path in a recording head from an ejection port communicating with the ink path, the ink supplied from an ink tank to the ink path is cleaned. a step of emptying the ink path by discharging it from the ejection port; a step of supplying a cleaning solvent from a cleaning solvent tank to the empty ink path; and a step of discharging the cleaning solvent filled in the ink path. A method for cleaning an inkjet recording apparatus, comprising the step of discharging the ink from an outlet to empty the ink path again.