JPH0929985A - Cleaning method of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an efficient cleaning method of an ink jet head by a method wherein the scorch produced on a heater part is removed by driving the ink jet head during non-recording operation with an aqueous solution containing electrolyte different from recording ink. SOLUTION: The outermost layer 6 of a heater is made of Ta, which is electrically insulated from a calorific heater part 10 and in which induced current occurs by energizing the calorific heater part 10 in pulses so as to cause electrochemical reaction in Ta by means of the current in order to melt Ta. As the removing liquid of scorch, the water solution consisting of one pt.wt. of ammonium phosphate, 20 pts.wt. of diethylene glycol and 79 pts.wt. of water is prepared and poured through the ink feeding port of a head. The discharging of the solution is performed by emplyng a driver to the head under the same driving conditions as those under the state being installed to a printer such as 1×10<5> pulses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning an ink jet head for recovering the function of the ink jet head which supplies thermal energy to ink supplied from an ink tank to generate bubbles and eject ink. Is.

[0002]

2. Description of the Related Art A liquid jet recording apparatus for ejecting a liquid by utilizing thermal energy uses, for example, an electrothermal converter as an energy generating means for ejecting the liquid, and the thermal energy generated here is converted into a liquid by its heat acting surface. It acts and vaporizes to generate bubbles. Recording is performed by ejecting the liquid from the ejection port due to the pressure variation of the liquid caused by the generation of the bubbles.

Recording by this system has advantages that a high resolution can be obtained in a recorded image and the recording head can be miniaturized because the ejection ports for ejecting the recording liquid can be arranged at a high density. Have

[0004]

In the recording head using the bubble jet method, the ink in the nozzle is heated by applying the electric pulse corresponding to the recording signal to the heater as described above, and the ink contacting with the heater is obtained. Is partially boiled to form air bubbles (bubbles), and the ink is ejected by the bubbles. When used for a long time, dyes, organic impurities, etc. in the ink are burnt on the heater and the foaming becomes unstable, Problems such as defective ejection of droplets and stable ejection of droplets may occur.

For this reason, conventionally, a dye having a high heat resistance was used and sufficient purification was performed to reduce the amount of impurities in the dye, thereby making it difficult to cause kogation.
There are problems that the manufacturing cost of the ink is high and the types of dyes that can be used are limited.

Furthermore, it is difficult to eliminate the occurrence of kogation even if a dye that hardly causes kogation is used. For example, in a printer of a type in which an ink tank is separated from an ejection head, ink is used. When the tank is replaced many times, or when the ink tank and the ejection head are integrated into the cartridge type head and ink is repeatedly refilled in the cartridge, kogation accumulates and ejection fails. It may happen. Also, it was not possible to recover the cartridge and regenerate the head at the recycling plant.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for cleaning an ink jet head capable of removing kogation occurring on the heater portion of the ink jet head. is there.

[0008]

Therefore, the method of cleaning an ink jet head according to the present invention has a function of an ink jet head which supplies thermal energy to ink supplied from an ink tank to generate bubbles to eject the ink. A method for cleaning an inkjet head for recovery, wherein an inkjet head is driven at the time of non-recording by using an aqueous solution containing an electrolyte different from that of the recording ink to remove kogation generated on the heater section that generates the thermal energy. Or the surface of the heater section that generates the thermal energy has electrical conductivity, and supplies an aqueous solution containing an electrolyte onto the heater section that generates the thermal energy. , Remove the kogation generated on the heater part by energizing the surface of the electrically conductive heater part With the configuration and having a that process, it is intended to achieve the above object.

Further, the aqueous solution containing the electrolyte is supplied by activating the ink jet head by a structure characterized by containing a phosphate ion or a structure characterized by containing a water-soluble organic solvent. The above-mentioned object is achieved by a structure characterized in that the number of pulses of electric power is 1 × 10 ⁶ or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been made in view of the above problems, and is characterized in that an aqueous solution containing an electrolyte is used to drive a heater, or the surface of the heater is energized to remove kogation.

According to the study of the present inventor, when driving is performed using an aqueous solution containing an electrolyte, an electrochemical reaction occurs due to an electric current flowing on the heater surface, and a part of the electrically conductive layer on the heater surface is dissolved. It became clear that kogation on the surface of the heater was peeled off from the heater together with the electrically conductive layer on the surface of the heater when it went out into the aqueous solution, and the kogation was removed. Further, according to the study of the inventor, as the electrolyte, Li ⁺ , Na ⁺ , K ⁺ , R as cation species are used.
Monovalent ions such as b ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , S
divalent ions such as r ²⁺ and Ba ²⁺ , trivalent ions such as Al ³⁺ ,
As anions, F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , OH ⁻ ,
Any known material such as NO ₃ ⁻ , SO ₄ ²⁻ , PO ₄ ³⁻ can be used, but especially when phosphoric acid (PO ₄ ³⁻ ) is contained, kogation can be efficiently removed.

The concentration of these electrolytes is 0.001N
~ 1N can be preferably used.

Further, it is desirable that the kogation removing liquid does not contain a coloring material, an organic impurity, a transition metal ion, etc. which cause kogation, because the kogation removing efficiency is high. However, if the kogation removal rate is high, a small amount of these may be contained, and in particular, a small amount of the color material may be added for the purpose of facilitating observation of the ejection state during kogation removal.

In addition, in order to stabilize foaming in the aqueous solution and to improve the solubility and removal efficiency of kogation components, water-soluble solvents such as alcohols, glycols, glycerin, ketones, ethers, amines, imines, etc. May be included.
Furthermore, as the liquid property of the aqueous solution, any of acidic, alkaline, and neutral can be used, but if acid or alkali is used depending on the material of the heater surface, the kogation removal rate can be increased. On the contrary, if a neutral removal liquid is used, the kogation removal speed is slightly slowed, but there is an advantage that damage to the constituent members of the head is reduced.

The driving method may be the same voltage and pulse waveform as in the case of recording an ordinary image, or may be higher voltage and longer pulse than those in the case of recording an image.
In the latter case, kogation can be removed faster than in the former case. On the contrary, the driving may be performed with a lower voltage and a shorter pulse, and further without ejecting droplets or causing foaming. In this case, it takes a longer time to remove kogation, but there is an advantage that damage to the heater surface can be reduced.

As the number of pulses applied to remove kogation, the more the number of pulses applied, the better the kogation is removed. However, in order to prolong the life of the heater for recording, it is preferable that the number of pulses is small. Therefore, 1 × 10 ⁶ pulses or less, more preferably 1 × 10 ⁵ pulses or less, and further preferably 1
A pulse number of × 10 ⁴ pulses or less is used.

Examples will be described below.

(Embodiment 1) In this embodiment, a used ink jet cartridge collected from a user will be described as an example in which kogation is removed and a head is regenerated in a recycling plant.

FIG. 1 is a perspective view of an ink jet cartridge, which comprises an ink tank portion 101 and an ink ejection portion (head) 102 including an ejection heater. In the recycling process, after performing a visual inspection of the cartridge and the like, the ink ejection unit 102 is separated from the ink tank unit 101 and kogation is removed.

FIG. 2 is an illustration of the ink ejecting section. In the actual kogation removal process, the discharge part is handled as it is, but it is shown in the assembly drawing in FIG. 2 for the sake of clarity. FIG. 3 is an explanatory view showing a cross section of the heater portion.

The heater outermost layer (6 in FIG. 3) is formed of tantalum (Ta). This Ta is electrically insulated from the exothermic heater part, but when the exothermic heater part is energized in a pulsed manner, an induced current is generated, and this current causes an electrochemical reaction of Ta to cause melting.

An aqueous solution having the following composition is prepared as a kogation removing liquid and is injected from the ink supply port of the head.

Ammonium phosphate 1 part by weight Diethylene glycol 20 parts by weight Water 79 parts by weight The head was driven by a driving driver under the same driving conditions as when the printer was mounted, and 1 × 10 ⁵ pulses were discharged.

In the actual recycling step, after the kogation removing step, the head is subjected to other necessary repair processing,
It is connected to an ink tank and regenerated.

In order to confirm the effect of this embodiment, the head before and after the kogation removal is disassembled, and the heater part (1 in FIG. 3) is disassembled.
As a result of observing (0), a brown to black lumpy deposit was observed before the kogation removal, but a bright yellow color of the Ta surface of the heater surface was observed after the kogation removal step. As for the ejection performance, the ejection speed was higher than that before the kogation removal, the speed variation (standard deviation of the ejection speeds of a plurality of times of the same nozzle) was small, and the ejection volume was increased. Although the kogation removing liquid of this embodiment is colorless, a small amount of coloring material may be added in order to easily know whether the ejection during the removing process is normal.

In the present embodiment, the heating heater is energized and the kogation is removed by the induced current. However, the kogation may be removed by directly passing a current to Ta on the heater surface.

(Embodiment 2) The ink jet head to be cleaned in this embodiment is the same as that in Embodiment 1 except that the heater portion has the structure shown in FIG.

The heater portion 10 of the ink jet head to be cleaned in this embodiment is characterized in that the heat generating portion is in direct contact with the ink as shown in FIG. Therefore, the heat transfer to the ink is efficient, and the foaming to the ejection can be efficiently performed. On the other hand, as a material of the heating resistor, an electrochemically stable material is used because an electrochemical reaction is likely to occur when it is in direct contact with the ink. For example, the heating resistor is TaIr.

After the ink tank and the ink ejection portion are separated in the same manner as in Embodiment 1, the following kogation removing liquid is used for driving.

0.01 part by weight of NaOH 100 parts by weight of water The head was filled with this solution, and 5 × 10 ⁴ pulses were discharged.

After that, it was promptly washed with pure water and another regeneration step was performed. Also in this example, it was confirmed that the burnout was removed and the discharge performance was improved.

(Embodiment 3) This embodiment is a cleaning method for removing kogation of the ink jet cartridge 200 called a separation tank system as shown in FIG.

According to this method, the ink tank 201 has the head 202 with the connecting claw 222 and the connecting claw guide groove 223.
The ink tank 201 can be easily replaced by the user. Therefore, by exchanging only the ink tank 201, the head portion 202 can be used for a long period of time, the running cost can be reduced, the amount of dust can be reduced, and the labor and cost of collection can be saved, and environmental problems can be reduced. Is also effective.

In FIG. 5, 220 is an ink supply hole, and 221 is an ink supply hole.

When the user replaces the ink tank or when the ink is still left in the ink tank and the print density is lowered or the image is disturbed due to kogation, the kogation removing liquid shown in FIG. 6 is used. By attaching the inlet tank 203 to the head 220 and performing ejection, kogation can be removed.

As the kogation removing liquid, the same one as used in Example 1 is packed in the tank 203 and supplied. At this time, it is desirable to change the tank shape and size so that it can be distinguished from the tank containing the recording ink. Also,
A mechanical shape or an electrical contact may be provided to identify that the printer body is the kogation removing liquid. It is also preferable to add a small amount of coloring material to the kogation removing liquid so that the user can surely know whether discharge for kogation removal is performed.

The number of pulses for removing kogation is 1 × 1.
0 is applied to about ⁵ pulses, a predetermined time to the user as the method, or a recording paper predetermined number, how get driving, a dedicated switch or a sequence for performing the kogation removal printer body provided to the user As a result, it is possible to use a method in which a drive for removing kogation is activated, a method in which the printer body automatically identifies the tank containing the kogation removal liquid, and performs driving.

[0038]

As described above, according to the present invention,
Even if kogation accumulates due to long-term use of the inkjet head, it can be removed, and the head can be recycled and repeatedly used for a long time.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an ink jet cartridge whose function is restored in a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an ink ejection unit of an inkjet cartridge.

FIG. 3 is a cross-sectional view of a heater unit of an ink jet cartridge whose function is restored in the first embodiment.

FIG. 4 is a cross-sectional view of a heater portion of an ink jet cartridge whose function is restored in the second embodiment.

FIG. 5 is a perspective view of a heater portion of an ink jet cartridge whose function is restored in the third embodiment.

FIG. 6 is an explanatory perspective view showing a process of Example 3.

[Explanation of symbols]

 1 Substrate 2 Heat Storage Layer 3 Heating Resistance Film 4 Wiring Conductor 5 Electrical Insulation Layer 6 Protective Film 10 Heater Section

Claims (7)

[Claims] 1. A method for cleaning an ink jet head, which recovers the function of an ink jet head for generating bubbles and ejecting ink by supplying thermal energy to the ink supplied from an ink tank, the electrolyte being different from a recording ink. A method for cleaning an inkjet head, comprising a step of driving an inkjet head at the time of non-recording by using an aqueous solution containing the above to remove kogation generated on the heater portion which generates the thermal energy. 2. A method of cleaning an ink jet head, which recovers the function of an ink jet head that supplies thermal energy to ink supplied from an ink tank to generate bubbles and eject ink, wherein the heater generates the heat energy. The surface of the part has electrical conductivity, and an aqueous solution containing an electrolyte is supplied onto the heater part that generates the thermal energy, and the surface of the electrically conductive heater part is energized to generate on the heater part. A method for cleaning an inkjet head, comprising the step of removing burnt deposits. 3. The method for cleaning an inkjet head according to claim 1, wherein the aqueous solution containing the electrolyte contains phosphate ions. 4. The inkjet head cleaning method according to claim 1, wherein the aqueous solution containing the electrolyte contains a water-soluble organic solvent. 5. The inkjet head cleaning method according to claim 1, wherein the number of pulses of electric power supplied to drive the inkjet head is 1 × 10 ⁶ or less. 6. The method for cleaning an inkjet head according to claim 1, wherein the aqueous solution containing the electrolyte does not contain a coloring agent. 7. The method for cleaning an inkjet head according to claim 1, wherein the aqueous solution containing the electrolyte contains a coloring agent.