JPH09187961A - Ink detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive ink detection method enhanced in the degree of freedom of arrangement and capable of certainly detecting the presence of ink by utilizing the electrochemical reaction generated by the ink interposed between a pair of electrodes by applying voltage across a pair of the electrodes connected to a power supply. SOLUTION: Ink 12 in which a pair of electrodes 11 are immersed contains urea for stabilization, diethylene glycol for preventing evaporation and an alcoholic solvent, for example, isopropyl alcohol other than a dye or pigment and water. A pair of the electrodes 11 connected to a power supply 14 through conductors 13 generate electrochemical reaction in an electrolyte soln., Herein, as the electrodes 11, nickel is employed and, when a predetermined voltage is applied across a pair of the electrodes 11 by the power supply 14, nickel constituting a positive electrode is reacted with ammonium hydroxide in the ink 12 to form nickel hydroxide and ammonium ions. By this constitution, a current flows across positive and negative electrodes by electrochemical reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the presence or absence of ink used in a printing apparatus or the like.

[0002]

2. Description of the Related Art In a printing apparatus using ink, particularly an ink jet printing apparatus, the amount of ink which is a consumable item is measured, and when the ink in an ink tank for storing the ink runs out, the printing operation is stopped. Process such as urging the user to replace the ink tank. In addition to the printing work, the amount of waste ink discharged from the inkjet head that ejects ink is measured, and when the amount of this waste ink reaches the holding capacity of the waste ink tank, the printing work is stopped, We also perform processing such as urging the replacement of the waste ink tank.

Therefore, in order to detect the amount of ink in the ink tank and the amount of waste ink in the waste ink tank,
The methods listed in the following are conventionally performed.
That is, a conductive ink is used and a pair of electrodes with good corrosion resistance, such as gold plating, is used, and a potential is applied between the pair of electrodes to apply a potential between the electrodes based on the presence or absence of energization. The presence or absence of intervening ink is detected.

The amount of waste ink is calculated by calculating the amount of ink discharged from the print head to estimate the amount of ink remaining in the ink tank, and by calculating the amount of ink discharged from the print head other than during printing. To estimate.

The presence or absence of ink is detected by detecting the state of transmission or reflection of ink using an optical sensor.

The amount of ink is detected by floating the float on the ink surface and measuring the position of the float.

By detecting the weights of the ink tank and the waste ink tank with the load sensors, the remaining ink amount and the waste ink amount are detected.

The amount of ink is detected by placing the ink in a flexible bag and detecting the expansion / contraction state of the bag.

[0009]

The conventional methods for detecting the amount of ink in the ink tank and the amount of waste ink in the waste ink tank have the following disadvantages. That is, in the method of adopting a conductive ink and electrically plating the electrodes with gold, the ink material is limited in order to make the ink conductive, and expensive gold plating is applied to the electrodes. There is a need.

In the method of estimating the amount of ink ejected from the print head by calculation, a relatively large error occurs. Therefore, as a result of outputting the warning of the remaining ink amount and the waste ink amount in anticipation of this error, it is still used Although it is possible, waste of replacing the ink tank or the waste ink tank occurs. To avoid this,
The cost for reducing the error increases and becomes expensive.

In the method using the optical sensor, the optical sensor is expensive and irradiates the measuring light into the ink tank and the waste ink tank. Therefore, it is necessary to make at least a part of the wall surface of these tanks transparent. The degree of freedom in arranging the optical sensor is low.

In the method using the float, there are restrictions on the shape and arrangement of the ink tank and the waste ink tank,
Moreover, since these tanks are large, they are not suitable for carrying.

In the method using the weight sensor, the sensor is expensive in order to improve the measurement accuracy, and the arrangement is limited.

In the method in which ink or waste ink is put in the bag and the expansion / contraction state thereof is detected, it is necessary to further install the bag inside the tank, which is wasteful in terms of cost. Also,
In the case of waste ink, there is a problem that air is mixed in the bag.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method which is inexpensive, has a high degree of freedom in arrangement, and can reliably detect the presence or absence of ink.

[0016]

According to the ink detection method of the present invention, a pair of electrodes is connected to a power source, a voltage is applied between the pair of electrodes, and an electricity generated by the ink interposed between the pair of electrodes is used. It is characterized in that the presence or absence of ink is detected by utilizing a chemical reaction.

Here, it is desirable that the ink is an electrolyte solution. In this case, it is effective that the ink contains urea. Further, the electrochemical reaction may be a chemical change of the positive electrode of the pair of electrodes, at least the surface of the positive electrode of the pair of electrodes is aluminum,
It is preferably coated with nickel, copper, or iron.

The ink detection method described above can also be applied to an ink jet device. That is, in an inkjet device having an ink tank for storing ink and an inkjet head having an ink ejection port for ejecting ink supplied from the ink tank via an ink supply passage, the A pair of electrodes interposed between the electrodes and an ammeter incorporated between one of the electrodes and the power source, and the presence or absence of ink is detected by utilizing a chemical reaction caused by the ink interposed between the pair of electrodes. It may be detected.

In this case, the pair of electrodes may be arranged at the bottom of the ink tank, in the middle of the ink supply passage, or in the housing of the ink jet device. In addition, an ink path communicating with the ink ejection port is formed in the inkjet head,
The pair of electrodes may be arranged in this ink path. Similarly, a waste ink tank for storing the ink discharged from the inkjet head may be further provided, and the pair of electrodes may be arranged in the waste ink tank. Further, the pair of electrodes may be arranged on various electric circuit boards (or electronic circuit boards).

The above-mentioned pair of electrodes may be formed on a flexible printed wiring board.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, which shows the principle of the ink detection method according to the present invention, the ink 12 in which the pair of electrodes 11 is dipped is a dye or pigment and water, and urea for stabilization. It contains diethylene glycol for evaporation prevention and an alcohol solvent such as isopropyl alcohol. Urea CO (NH _{2) 2} is reacted with water H ₂ O to produce ammonia NH _3, ammonia NH ₃
Reacts with water H ₂ O to give ammonium hydroxide NH ₄
Since it becomes OH, the ink 12 becomes a weakly basic electrolyte solution. That is, CO (NH ₂ ) ₂ + H ₂ O → 2NH ₃ + CO ₂ NH ₃ + H ₂ O → NH ₄ OH.

The pair of electrodes 11 connected to the power source 14 through the lead wire 13 are those that cause an electrochemical reaction (electrode reaction) in the electrolyte solution, that is, those that have a high ionization tendency and do not form an oxide film. Is desirable. Specifically, aluminum, nickel, copper, iron or the like can be used. Among these, nickel is suitable for the electrode 11 of the present embodiment because it is easy to plate and form a film and forms a hydroxide film in water.

When nickel is used as the electrode 11 and a predetermined voltage is applied between the pair of electrodes 11 by the power source 14, the nickel Ni constituting the positive electrode reacts with ammonium hydroxide NH ₄ OH in the ink 12. Nickel hydroxide Ni (OH) ₂ and ammonium ion NH ₄ ⁺ are produced. That is, Ni + 2NH ₄ OH → Ni (OH) ₂ + 2NH ₄ ⁺ + 2e ⁻ , and this ammonium ion NH ₄ ⁺ reacts with water H ₂ O at the negative electrode to generate ammonium hydroxide NH ₄ OH and hydrogen H ₂ . That is, 2NH ₄ ⁺ + 2H ₂ O + 2e ⁻ → 2NH ₄ OH + H _{2 is obtained} , and a current flows between the positive electrode and the negative electrode by such an electrochemical reaction.

An ammeter 15 is provided in the middle of the lead wire 13 for connecting the negative electrode and the power source 14, and the pair of electrodes 11
If there is ink 12 between them, this ammeter 1
Since it is possible to confirm that an electric current is flowing by means of 5, it can be determined that the ink 12 is present between the pair of electrodes 11. Further, when the ink 12 is not present between the pair of electrodes 11, it can be confirmed by the ammeter 15 that no current is flowing. Therefore, it is determined that there is no ink 12 between the pair of electrodes 11. It will be possible.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the ink detecting method according to the present invention is applied to detect the presence or absence of ink in an ink cartridge of an ink jet apparatus will be described with reference to FIG.

That is, the ink cartridge in this embodiment includes an ink tank 21 for storing the ink 12.
An ink jet head 22 having an ink ejection port (not shown) for ejecting the ink 12 is integrally assembled, and the ink jet head 22 is positioned below the ink tank 21 when used.
It is detachably mounted on a carriage of an inkjet device (not shown). A connector portion 23 for electrically connecting to the carriage side is formed on the outer side wall of the ink tank 21, and the connector portion 23 has
A head wiring portion 24 formed on the outer side wall of the inkjet head 22 for electrically controlling the ejection of the ink 12 from the ink ejection port is connected.

The ink 12 in the ink tank 21 is supplied to the ink jet head 22 through an ink supply passage (not shown) having an opening 25 formed at the bottom of the ink tank 21. A pair of electrodes 11 plated with nickel are attached to the wall surface portion forming the opening 25 described above, and between the ink tank 21 and the ink jet head 22, the electrodes 11 and the previous connector portion are provided. Ink detection wiring 26 is provided to connect 23 to 23. The head wiring portion 24 and the pair of electrodes 11 are connected to a power source (not shown) provided on the main body side of an inkjet device (not shown) incorporating a carriage. further,
An ammeter (not shown) provided on the main body side of the inkjet device is interposed between the power source and one of the electrodes 11.

Therefore, when the ink 12 is not present in the electrode 11 portion, that is, when the ink tank 21 is empty, no current flows through the ammeter described above, and the ink 12 in the ink tank 21 is empty. By issuing a warning to that effect, it is possible to prompt replacement of the ink cartridge. In this case, based on the amount of ink remaining in the ink supply passage and the ink jet head 22, the subsequent ink ejection operations are counted to estimate the ink-less state almost accurately and interrupt the printing operation. By doing so, it is possible to prevent printing work without ink.

In this case, a voltage is applied between the pair of electrodes 11 to detect the presence or absence of ink in the ink tank 21 before the printing operation by the ink jet device, while the voltage application to the electrodes 11 is stopped in other states. By doing so, it is possible to avoid wasteful power consumption and minimize the generation of bubbles.

In the above embodiment, the electrode 11 is arranged at the bottom of the ink tank 21, but the ink jet head 22
It is also possible to incorporate it in the ink chamber formed inside, and an exploded structure of such another embodiment is shown in FIG.
Members having the same functions as those in the previous embodiment are designated by the same reference numerals, and duplicate description will be omitted.

That is, the ink jet head 22 integrally formed with the ink tank 21 is formed with an opening 31 whose one end faces the other end of an ink supply passage (not shown) communicating with the inside of the ink tank 21. Heater board 3 having a communication hole 32 communicating with 31 formed in the central portion
3 is attached to the tip of the inkjet head 22.
Further, a nozzle plate 36 having a plurality of ink ejection openings 34 and a pair of dummy ejection openings 35 formed at predetermined intervals is superposed on the heater board 33, and the ink ejection openings 34 and the dummy ejection openings 35 are interposed between them. An ink path (not shown) that is connected to each of the ink paths and a common ink chamber (not shown) that communicates with the base ends of these ink paths are formed. On the heater board 33 facing each ink path, the electrothermal conversion element 3 that ejects a predetermined amount of ink from the ink ejection port 34 by boiling the ink in the ink path.
7 are provided.

However, in this embodiment, the heater board 33 facing the ink path communicating with the dummy ejection port 35 is not the electrothermal conversion element 37 described above but a pair of electrodes 11 having nickel plating on the surface. Is provided,
Although the ink is not ejected from the dummy ejection port 35, the ink in each ink path is ejected from the ink ejection port 34 and the dummy ejection port 35 by using a pump or the like (not shown) during the recovery process of the inkjet head 22. When sucked to the recovery means side, the ink is reliably drawn into the ink passage of the dummy ejection port 35.

These electrothermal conversion element 37 and electrode 11
A board wiring portion 38 formed on the heater board 33 is connected to the electrothermal conversion element 37 and the electrode 1.
1 and the board wiring portion 38 can be formed using a film forming technique on a silicon wafer or the like. Further, the tab portion 39 of the head wiring portion 24 provided on the outer side wall of the inkjet head 22 is superposed on the board wiring portion 38 described above.

Therefore, by detecting the presence / absence of ink in the ink path exposed by the pair of electrodes 11, it is possible to accurately grasp whether or not there is ink in the ink chamber. The surface of the heater board 33 other than the electrodes 11 and the board wiring portion 38 is covered with a protective film (not shown) to withstand corrosion, current leakage, and the like.

In this case, a voltage is applied between the pair of electrodes 11 to detect the presence / absence of ink in the ink path before the printing operation by the ink jet device, and then a small amount of hydrogen bubbles generated in the ink path is removed. Therefore, it is desirable to discharge the ink in the ink passage in advance. In addition, by stopping the application of the voltage to the electrode 11 in other states, it is possible to avoid unnecessary power consumption and minimize the generation of bubbles.

An embodiment in which the ink detecting method according to the present invention is applied to a waste ink tank in an ink jet device will be described with reference to FIG. 4 showing a schematic structure thereof.

That is, the waste ink generated on the side of the ink jet head (not shown) during the recovery process is stored in the waste ink tank 42 by the waste ink collecting pipe 41. In the present embodiment, the inside of the waste ink tank 42 is left as a hollow, but the waste ink is discharged due to vibration or the like.
The ink absorber may be filled inside so as not to scatter from the inside. A tip end portion of a flexible printed wiring board is attached to an inner wall of an upper end portion of the waste ink tank 42, and the flexible printed wiring board 43 communicates with the pair of electrodes 11 and the pair of electrodes 11. The conducting wire 13 is printed. The surface of the electrode 11 is covered with a thin film of nickel, the conductor 13 is connected to a power source (not shown), and an ammeter (not shown) is provided on one side of the conductor 13.

Therefore, when the liquid surface of the waste ink in the waste ink tank 42 reaches the portion of the electrode 11, the pair of electrodes 11 are energized via the waste ink, and the waste ink from the ink jet head side is thus discharged. It is possible to issue a request to stop the discharge of the waste ink or to dispose the waste ink in the waste ink tank 42.

When ink adheres to various electric circuit boards (or electronic circuit boards) of an ink jet device, various problems such as defective conductivity may occur. The present invention can be applied to such a case.

That is, as shown in FIG. 5 showing an example of such an electric circuit board, a pair of electrodes 11 having predetermined intervals are formed in a pattern on the peripheral portion of the electric circuit board 51. The surface of 11 is covered with a nickel thin film. In addition, the electric circuit board 51
Above it is a connector 52 for connecting to a power supply not shown.
The terminals of the electrodes 11 are connected to the connectors 52, respectively. Each electrode 11 in this embodiment is
Although they are formed in a comb shape and face each other so as to be engaged with each other with a gap therebetween, there is no problem even if the shape is other than this.

Therefore, when the ink leaks onto the pair of electrodes 11 of the electric circuit board 51 for some reason, the pair of electrodes 11 becomes conductive and the presence of the ink can be detected. , Electric circuit board 5 due to leakage, corrosion, etc.
1 can be prevented from being damaged.

In this case, a voltage is constantly applied between the pair of electrodes 11 to detect the presence or absence of ink, and when the presence of ink is detected, safety measures such as power-off are taken. However,
In a normal state, since ink does not exist between the pair of electrodes 11, even if a voltage is constantly applied between the pair of electrodes 11, unnecessary power consumption does not occur.

In the fourth embodiment described above, the electric circuit board 51 is used.
Although the presence or absence of the above ink is detected, it can also be applied to the housing of an inkjet device, and as shown in FIG. 6 showing the external appearance of the electrode portion used in such a case, A pair of electrodes 11 is formed in a pattern on a rectangular flexible printed wiring board 61, and the surfaces of these electrodes 11 are covered with a thin film of nickel. A connector 62 for connecting to a power source (not shown) is connected to one corner of the flexible printed wiring board 61.
The terminal of the electrode 11 described above is connected to the. Similar to the embodiment shown in FIG. 5, each electrode 11 in this embodiment is
Although they are formed in a comb shape and face each other so as to be engaged with each other with a gap therebetween, there is no problem even if the shape is other than this.

Such a flexible printed wiring board 6
By mounting No. 1 on, for example, the bottom plate portion of the housing, it is possible to confirm that ink or the like has leaked onto this bottom plate, and take necessary measures to prevent ink leakage to the outside of the device. It becomes possible.

In this case, a safety measure is implemented such that a voltage is constantly applied between the pair of electrodes 11 to detect the presence or absence of ink, and a warning is issued when the presence of ink is detected. However, since ink does not exist between the pair of electrodes 11 in a normal state, wasteful consumption of electric power does not occur even if a voltage is constantly applied between the pair of electrodes 11.

[0046]

According to the ink detection method of the present invention, a pair of electrodes is connected to a power source, a voltage is applied between the pair of electrodes, and an electrochemical reaction generated by the ink interposed between the pair of electrodes is utilized. Since it is possible to detect the presence or absence of ink, there is no need to use conductive ink or expensive gold plating on the electrodes, it is inexpensive and has a high degree of freedom of arrangement, and the presence or absence of ink can be ensured. Can be detected.

When the ink detection method of the present invention is applied to an ink tank of an ink jet device, the presence or absence of ink in this ink tank can be detected. Similarly,
When applied to the ink path of an inkjet head,
The presence or absence of ink in this ink path can be detected.

When the ink detection method of the present invention is applied to the waste ink tank of an ink jet device, the waste ink storage limit in this waste ink tank can be detected, and the waste ink above this limit can be discharged. As a safety measure, it is not necessary to set a large capacity of the waste ink tank or use another expensive ink detection device, and it is possible to implement the safety measure with an inexpensive and simple configuration. Becomes

Furthermore, when the ink detection method of the present invention is applied to an electric circuit board or an electronic circuit board, ink leakage onto the electric circuit board or the electronic circuit board can be detected, and these circuit boards can be detected. It is possible to prevent damage in advance.

Similarly, when the present invention is applied to the housing of an ink jet apparatus, ink leakage inside the housing can be detected and ink leakage outside the apparatus can be prevented. Therefore, as a safety measure, an ink tank. Since it is not necessary to install an ink leakage prevention mechanism in the waste ink tank, it is possible to implement safety measures with an inexpensive and simple structure.

[Brief description of the drawings]

FIG. 1 is a principle diagram of an ink detection method according to the present invention.

FIG. 2 is a sectional view showing a schematic structure of an ink cartridge in an example in which the method of the present invention is applied to an ink tank of an inkjet device.

FIG. 3 is an exploded perspective view of an ink cartridge in an example in which the method of the present invention is applied to an ink path of an inkjet head.

FIG. 4 is a perspective view of an embodiment in which the method of the present invention is applied to a waste ink tank of an inkjet device.

FIG. 5 is a perspective view showing an appearance of an embodiment in which the method of the present invention is applied to an electric circuit board, and is a partially enlarged view in which a part thereof is extracted and enlarged.

FIG. 6 is a perspective view showing the appearance of an embodiment in which the method of the present invention is applied to a flexible printed wiring board.

[Explanation of symbols]

 11 Electrodes 12 Ink 13 Conductive Wire 14 Power Supply 15 Ammeter 21 Ink Tank 22 Inkjet Head 23 Connector Section 24 Head Wiring Section 25 Opening 26 Ink Detection Wiring 31 Opening 32 Communication Hole 33 Heater Board 34 Ink Discharging Port 35 Dummy Discharging Port 36 Nozzle Plate 37 Electrothermal Conversion Element 38 Board Wiring Section 39 Tab Section 41 Waste Ink Collection Tube 42 Waste Ink Tank 43 Flexible Printed Wiring Board 51 Electrical Circuit Board 52 Connector 61 Flexible Printed Wiring Board 62 Connector

Claims (10)

[Claims] 1. A pair of electrodes is connected to a power source, a voltage is applied between the pair of electrodes, and the presence or absence of ink is detected by utilizing an electrochemical reaction caused by the ink interposed between the pair of electrodes. An ink detection method characterized by the above. 2. The ink detection method according to claim 1, wherein the ink is an electrolyte solution. 3. The ink detection method according to claim 1 or 2, wherein the ink contains urea. 4. The ink detection method according to claim 1, wherein the electrochemical reaction is a chemical change of a positive electrode of the pair of electrodes. 5. The method according to claim 1, wherein at least the surface of the positive electrode of the pair of electrodes is coated with aluminum, nickel, copper, or iron. Ink detection method. 6. The pair of electrodes is located in an ink supply passage between an ink tank that stores ink and an inkjet head that discharges ink supplied from the ink tank. The ink detection method according to claim 1. 7. The ink detection device according to claim 1, wherein the pair of electrodes are located in a common ink chamber formed in an inkjet head that ejects ink. Method. 8. The ink detecting method according to claim 1, wherein the pair of electrodes are provided at an upper end portion of a waste ink tank from which ink is discharged. 9. The ink detection method according to claim 1, wherein the pair of electrodes are formed on a surface of a printed wiring board. 10. The ink detection method according to claim 9, wherein the printed wiring board is a flexible printed wiring board.