JP2024082946A - Liquid discharge head, liquid discharge device, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head configured that a life of the head for removing scorch is determined for each head and can be replaced at proper timing.

SOLUTION: A liquid discharge head comprises: a discharge port for discharging liquid; a liquid chamber communicated with the discharge port; a heat generating element for generating energy required for discharging liquid; a protecting layer for blocking contact of the heat generating element with the liquid; a first electrode arranged on the protecting layer to cover at least the heat generating element and constituted of materials including metal that is eluted by an electrochemical reaction with the liquid; a second electrode for making the electrochemical reaction arise, provided to be electrically connectable to the first electrode through the liquid inside the liquid chamber; measuring means that measures a value concerning a film thickness of the first electrode and is utilized for measuring information concerning permissivity of execution of scorch removal that is executed to the first electrode; and a memory for memorizing the information.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

This disclosure relates to a liquid ejection head, a liquid ejection device, a control method, and a program.

One type of liquid ejection method is a recording device that employs the inkjet recording method. This recording device ejects liquid such as ink from ejection ports provided in a liquid ejection head, and records by depositing the liquid onto a recording medium such as paper. Inkjet recording methods include a method of ejecting liquid by utilizing the bubbling of liquid caused by thermal energy generated by electrothermal conversion elements, which enables high-quality and high-speed recording.

The liquid ejection head described above generally has multiple ejection ports, flow paths that communicate with each of the multiple ejection ports, and multiple electrothermal conversion elements that generate thermal energy used to eject ink. The electrothermal conversion elements are composed of a heating resistor and electrodes for supplying power to the heating resistor. The electrothermal conversion elements are covered with a lower protective layer having insulating properties, such as silicon nitride, thereby ensuring insulation between the ink and the electrothermal conversion elements.

When liquid is ejected, the heat generating portion of the electrothermal conversion element is exposed to high temperatures and is subjected to a combination of shocks caused by cavitation due to the bubbling and contraction of the liquid and chemical action of the ink. Therefore, an upper protective layer is provided on the heat generating portion to protect the heat generating resistor from shocks caused by cavitation and chemical action of the ink. The surface of this upper protective layer heats up to around 700°C and comes into contact with the ink, so it is required to have excellent film properties such as heat resistance, mechanical properties, chemical stability, and alkali resistance.

However, when heated to high temperatures, the coloring materials and additives contained in the ink break down at the molecular level, turning into a difficult-to-dissolve substance known as "kogane." When this kogane physically adheres to the upper protective layer, the heat transfer from the heating resistor to the ink becomes uneven, causing problems such as a slower ink ejection speed, unstable bubbling, and an increase in the energy required for ejection.

As a technique for addressing such problems, Patent Document 1 discloses a technique for removing kogation by forming the surface of the upper protective layer from a material that can be dissolved by an electrochemical reaction, such as iridium or ruthenium.

In the cleaning method for removing kogation disclosed in Patent Document 1, a positive potential is applied to a material layer that can be dissolved by an electrochemical reaction in liquid, causing the material layer to dissolve into the liquid, thereby removing the kogation adhering to the material layer. This material layer must have a film thickness of at least a specified value to protect the heating resistor from impacts caused by cavitation during ejection and from chemical reactions caused by the ink. Therefore, as the material layer dissolves due to cleaning, it is necessary to manage the amount of material layer dissolved by kogation removal so that the head can be replaced when the remaining amount of the material layer falls below a specified value.

Generally, the amount of elution of a material layer depends on the amount of electricity (coulomb amount) passing through the material layer, and if the conductivity of the liquid does not change, the amount of elution of the material layer at a constant voltage does not change, so the number of times kogation removal can be performed when using this material layer can be calculated in advance. However, the number of times kogation removal can be performed varies slightly depending on manufacturing variations in ink lots and manufacturing variations in the material layer. For example, if an ink that dissolves the material layer more easily is combined with a thinner material layer within the range of manufacturing variations, the number of times kogation removal can be performed will be reduced. On the other hand, if an ink that dissolves the material layer less easily is combined with a thicker material layer within the range of manufacturing variations, the number of times kogation removal can be performed will be increased.

JP 2008-105364 A

However, in Patent Document 1, when the number of times kogation removal can be performed is preset for each head, this number must be set to the minimum value among the values expected within the range of manufacturing variation. The reason for this is that if a value exceeding the minimum value is set, there is a possibility that kogation removal will be performed more than the allowable number of times, which poses the risk of head failure.

When the number of times kogation removal can be performed is set in this way taking manufacturing variations into account, depending on the head, it may be set to a number less than the number of times it can actually be performed. As a result, for a head that has performed kogation removal a preset number of times, even if kogation removal is still possible, it is considered to have reached the end of its life and cannot perform any more kogation removal, and the head must be replaced.

In view of the above problems, the present disclosure aims to provide a liquid ejection head that can determine the head lifespan for kogation removal for each head and can be replaced at the appropriate time.

One embodiment of the present invention is a liquid ejection head having an ejection port for ejecting liquid, a liquid chamber communicating with the ejection port, a heating element for generating the energy required to eject the liquid, a protective layer for blocking contact between the heating element and the liquid, a first electrode arranged on the protective layer so as to cover at least the heating element and made of a material containing a metal that dissolves by an electrochemical reaction with the liquid, a second electrode that is electrically connectable to the first electrode via the liquid inside the liquid chamber and causes the electrochemical reaction, a measuring means used to measure a value related to the film thickness of the first electrode and to measure information related to the permissibility of kogation removal to be performed on the first electrode, and a memory for storing the information.

This disclosure makes it possible to determine the lifespan of each head with respect to kogation removal and provide a liquid ejection head that can be replaced at the appropriate time.

FIG. 1 is a perspective view showing a schematic internal configuration of a recording apparatus; FIG. 3 is a perspective view showing the configuration of a head unit; FIG. 1 is a perspective cross-sectional view showing a schematic configuration of a recording element substrate; FIG. 3 is a cross-sectional view showing the configuration in the vicinity of a heating resistor in a recording head. FIG. 1 is a diagram for explaining the relationship between film thickness and resistance value. 1 is a flowchart of a first measurement process for measuring a time during which burnt removal can be performed. FIG. 2 is a plan view showing a schematic configuration of a recording element substrate; FIG. 3 is a cross-sectional view showing the configuration in the vicinity of a heating resistor in a recording head. 11 is a flowchart of a second measurement process for measuring a time during which burnt removal can be performed. 11 is a flowchart of a third measurement process for measuring the number of times that burnt removal can be performed. 4 is a flowchart of a fourth measurement process for measuring the number of times that burnt removal can be performed.

The technical feature of the present disclosure is to set the time and number of times that the kogation removal can be performed appropriately for each head. The contents of the present disclosure will be described in detail below with reference to the drawings. The following embodiments do not limit the present disclosure more than necessary, and not all of the combinations of features described in the following embodiments are necessarily essential as the means of solving the problems of the present disclosure. Furthermore, the relative positions and shapes of the components described in the following embodiments are merely examples unless otherwise specified, and are not intended to limit the scope of the present disclosure to only those. In this specification, a device that ejects liquid such as ink is called a "liquid ejection device," and an example of a liquid ejection device is an inkjet recording device. Furthermore, a head that ejects liquid such as ink is called a "liquid ejection head," and an example of a liquid ejection head is a recording head that an inkjet recording device has. Furthermore, ink, a treatment liquid for improving the fixability of ink, a treatment liquid for improving gloss, etc. are collectively called "liquid."

[First embodiment]
<Configuration of Recording Device>
First, a liquid ejection device having a liquid ejection head according to the first embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a perspective view showing a schematic internal configuration of a recording device having a recording head according to this embodiment, with a part cut away. Fig. 2 is a perspective view showing the configuration of a head unit. In this specification, an inkjet recording device (hereinafter abbreviated as "recording device") that ejects ink onto a recording medium to perform recording will be described as an example of a liquid ejection device. Therefore, in this recording device, the recording head that ejects ink to perform recording corresponds to the liquid ejection head that ejects liquid. As shown in Fig. 1, the longitudinal direction of the recording device 500 is defined as the X direction, the lateral direction is defined as the Y direction, and the height direction is defined as the Z direction.

The recording device 500 has a carriage 505 to which the head unit 410 can be detachably attached. The carriage 505 is attached to a belt 501 that is endlessly stretched between a drive pulley 503A and a driven pulley 503B. The carriage 505 is also slidably mounted on a guide shaft 502 that is arranged parallel to the extension direction of the belt 501. When the drive pulley 503A, which is driven by a carriage motor 504, rotates, the belt 501 rotates, and the carriage 505 moves in the direction of arrow A while being supported by the guide shaft 502. In other words, the carriage 505 is configured to be able to move back and forth as shown in the direction of arrow A according to the rotation direction of the drive pulley 503A.

The recording device 500 has an encoder sensor 508. The encoder sensor 508 detects the slits of a linear scale 507 extending in the X direction. The control unit of the recording device 500 detects the position of the carriage 505 in the X direction based on the detection result of the linear scale 507 by the encoder sensor 508.

The recording device 500 has a first conveying roller pair consisting of conveying rollers 509 and 510, and a second conveying roller pair consisting of conveying rollers 511 and 512. These conveying rollers are rotated by a conveying motor to convey the recording medium P in the direction of arrow B. The first conveying roller pair is located upstream in the Y direction, which is the conveying direction of the recording medium P, and the second conveying roller pair is located downstream in the Y direction. The first conveying roller pair and the second conveying roller pair are located in the Y direction so as to sandwich the area where ink is ejected by the head unit 410. The first conveying roller pair and the second conveying roller pair convey the recording medium P while nipping it, thereby maintaining the smoothness of the recording medium P at a position facing the recording head in the head unit 410.

In the recording device 500, a recording operation is performed by the control unit. The recording operation is an operation in which, while driving the carriage motor 504, the recording head of the head unit 410 ejects ink onto the recording medium P in accordance with recording data based on the detection results of the encoder sensor 508. When the control unit performs the recording operation, one band of image is recorded on the recording medium P. The control unit then drives the transport motor to perform a transport operation that transports the recording medium P in the direction of arrow B a distance equivalent to one band. In this way, the recording device 500 alternates between the recording operation and the transport operation to form a recorded image on the recording medium P.

The recording device 500 also includes a recovery unit 513 for performing maintenance on the recording head of the head unit 410 at a home position located at one end in the direction of arrow A. The recovery unit 513 includes a cap member for protecting the recording head and a pump for suctioning to generate negative pressure within the cap member.

As shown in FIG. 1, four head units 410 are arranged on the carriage 505. The first head unit of the four head units 410 is configured to eject cyan ink, the second head unit to eject magenta ink, the third head unit to eject yellow ink, and the fourth head unit to eject black ink. Each head unit 410 includes a tank that contains ink and a recording head for ejecting the ink contained in the tank. The head unit 410 also includes a wiring tape 402 (see FIG. 2) for supplying recording data, power, and the like to the recording head. As shown in FIG. 2, the wiring tape 402 includes contacts 403 for electrically connecting the head unit 410 to the recording device 500 when the head unit 410 is attached to the carriage 505.

In the recording device 500 according to the present embodiment, the head unit 410 is integrated with the tank and the recording head, but the present invention is not limited to this. In other words, the tank and the recording head may be separated. Specifically, the recording head is provided on the carriage 505, and ink is supplied to the recording head from a tank detachably provided in the recording device 500 via a tube or the like. In this case, a recording head may be provided for each color, or only one recording head capable of ejecting four inks may be provided. The number of inks used in the recording device 500 and the types of liquids ejected are not limited to those listed above. In other words, the number of inks may be only one color, or may be two, three, or five or more colors, and the type of liquid may be a processing liquid (fixing liquid, gloss agent, etc.) that performs a predetermined process on the recording medium P, other than ink.

<Liquid ejection head>
The configuration of the liquid ejection head will be described below with reference to FIG. 3. FIG. 3 is a perspective half-sectional view showing a schematic configuration of a recording element substrate 100 constituting a recording head as an example of a liquid ejection head according to this embodiment. The recording element substrate 100 includes a substrate 110 on which a liquid supply path 176 for supplying ink to a liquid chamber 172 and a liquid recovery path 174 for recovering ink from the liquid chamber 172 are formed. On one surface (hereinafter referred to as a first surface) of the substrate 110, a nozzle member 170 is provided on which an ejection port array consisting of a plurality of ejection ports 171 for ejecting ink is formed. In addition, on the other surface (hereinafter referred to as a second surface) of the substrate 110 facing the first surface, a cover plate 180 is formed.

The liquid supply path 176 and the liquid recovery path 174 extend along the extension direction of the ejection port array in the nozzle member 170. Furthermore, on the first surface of the substrate 110, a plurality of supply ports 173 communicating with the liquid supply path 176 are arranged along the extension direction of the ejection port array. Furthermore, on the first surface of the substrate 110, a plurality of recovery ports 177 communicating with the liquid recovery path 174 are arranged along the extension direction of the ejection port array.

A thermal action section for foaming the ink with thermal energy is formed on the first surface of the substrate 110 at a position corresponding to the ejection port 171. This thermal action section is made up of a recording element 150 (the recording element is also called a "heating resistor", "heating resistance element" or "electrothermal conversion element") (see FIG. 4) for ejecting ink to perform recording, and an electrode (first measurement electrode 301) that also serves as a cavitation-resistant layer to protect the heating resistor 150. The thermal action section is located inside a liquid chamber 172 formed in the nozzle member.

In addition, a terminal 190 is formed on the first surface of the substrate 110, which is electrically connected to the heating resistor 150 by electrical wiring (not shown) provided on the substrate 110. Therefore, the heating resistor 150 generates heat based on a pulse signal input via an external wiring board (not shown), boiling the ink in the liquid chamber 172. The force of bubbles caused by this boiling causes the ink to be ejected from the ejection port 171.

The cover plate 180 is provided with an opening 175 that communicates with the liquid supply path 176 and an opening (not shown) that communicates with the liquid recovery path 174. Ink is supplied to the recording head from this opening 175, and ink is recovered from the recording head through an opening that communicates with the liquid recovery path 174. Therefore, in the recording element substrate 100, as shown by arrow C, ink is supplied to the liquid chamber 172 through the opening 175, the liquid supply path 176, and the supply port 173. In addition, the ink supplied to the liquid chamber 172 is recovered through the recovery port 177, the liquid recovery path 174, and an opening that communicates with the liquid recovery path 174.

<Liquid ejection head substrate>
FIG. 4 is a cross-sectional view that shows a schematic diagram of a recording element substrate 100 as a liquid ejection head substrate according to this embodiment.

A heating resistor 150 is provided on the recording element substrate 100 on which a semiconductor element (not shown) is formed. An insulating protective layer (not shown) is formed on the heating resistor 150 to ensure insulation between the liquid and the heating resistor 150, and a cavitation-resistant layer 120 is formed on the insulating layer 150 to protect the heating resistor from impacts due to cavitation and chemical reactions due to ink. A nozzle member 170 is formed on the cavitation-resistant layer 120, and a liquid chamber 172 covered with a nozzle material is filled with liquid, and the nozzle member 170 is provided with an ejection port 171 for ejecting the liquid. The heating resistor 150 generates heat when given electrical energy, and imparts heat, which becomes ejection energy, to a part of the liquid above the heating resistor 150. The heating resistor is also called a "heating (resistance) element."

<Removing burnt food>
As shown in Fig. 4, a first electrode 121 and a second electrode 122 are formed on the recording element substrate 100 by a cavitation-resistant layer 120. The first electrode 121 and the second electrode 122 are electrically connected by a wiring path having a power source 142 and a switch 141, and can form an electrical closed circuit via the liquid in the liquid chamber 172. The components that make up this closed circuit are called "cleaning means." In this way, the first electrode 121 and the second electrode 122 are provided so as to be electrically connectable. The cleaning means may be provided in the liquid ejection head, or may be provided in the recording device instead of the liquid ejection head.

The heating resistor 150 applies heat energy a predetermined number of times during a recording (printing) operation, and during this application, the switch 141 of the cleaning means is open or the power supply from the power source 142 is stopped. After a certain amount of kogane has accumulated on the surface of the first electrode 121 above the heating portion of the heating resistor 150, a cleaning process is performed to remove the kogane. In the cleaning process, an electrochemical reaction occurs at the interface between the first electrode 121 and the liquid by closing the circuit of the cleaning means. This electrochemical reaction dissolves the surface of the first electrode 121 into the liquid, removing the kogane adhering to the surface of the first electrode 121.

The recording head has a first electrode 121, a second electrode 122, and a wiring layer that forms part of the wiring path. A typical recording device has a switch 141 and a power supply 142 outside the recording head, but in some cases, the switch 141 may be inside the recording head.

<Method for estimating remaining film thickness using resistance value>
As shown in Fig. 4, the recording element substrate 100 has a first measurement electrode 301 and a second measurement electrode 302 as a measurement means 300 for measuring a value related to the film thickness of the first electrode. Information obtained by the measurement means 300 is stored in a memory 310 (see Fig. 6) mounted on the liquid ejection head. The memory 310 may be formed on the recording element substrate 100, or may be outside the recording element substrate 100 as long as it is within the liquid ejection head. The memory 310 may be, for example, an EEPROM mounted on the liquid ejection head.

The measuring means 300 has a first measuring electrode 301 and a second measuring electrode 302. The first measuring electrode 301 and the second measuring electrode 302 are electrically connected by a wiring path having a power source 142 and a switch 141, and can form an electrical closed circuit via the liquid in the liquid chamber 172. The first measuring electrode 301 and the second measuring electrode 302 are formed of the same material as the first electrode 121 and the second electrode 122, and can be formed of a material containing a metal that can be dissolved by an electrochemical reaction, such as iridium or ruthenium. In addition, it is preferable that the first measuring electrode 301 is formed in the same pattern as the first electrode 121, and it is preferable that the second measuring electrode 302 is formed in the same pattern as the second electrode 122.

Since the measurement means 300 does not eject ink, the first measurement electrode 301 is not actually subjected to kogane removal, but an electrochemical reaction occurs by applying a voltage between the first measurement electrode 301 and the second measurement electrode 302, as in the above-mentioned kogane removal. This is called "virtual kogane removal". The first measurement electrode 301 is connected to a measurement means 700 for measuring the resistance value of the measurement means 300. The measurement means 700 can measure the resistance value of the first measurement electrode 301. In this embodiment, the measurement means 700 is provided inside the liquid ejection head, but it may be outside the liquid ejection head. Since it is necessary to apply a potential to the first measurement electrode 301 whose resistance value is measured, it is preferable to measure the resistance value when virtual kogane removal is not being performed. The surface of the first measurement electrode 301 is dissolved into the ink by an electrochemical reaction every time virtual kogane removal is performed, and as a result, the film thickness of the first measurement electrode 301 becomes thinner. As will be described later with reference to FIG. 5, as the film thickness becomes thinner, the resistance value of the first measurement electrode 301 becomes higher. Therefore, by utilizing this property, the remaining thickness of the first electrode 121 (cavity-resistant film) formed by the cavity-resistant layer 120 can be estimated based on the magnitude relationship between the measured resistance value and a predetermined threshold value related to the resistance value.

The relationship between film thickness and resistance will now be described with reference to FIG. 5. FIG. 5 is a diagram for explaining the relationship between the film thickness of the first measurement electrode 301 and the resistance. FIG. 5(a) shows a schematic diagram of the first measurement electrode 301 in a relatively thick state, FIG. 5(b) shows a state in which the film thickness is thinner than that of FIG. 5(a), and FIG. 5(c) shows a state in which the film thickness is thinner than that of FIG. 5(b). FIG. 5(d) is a graph showing the relationship between film thickness and resistance, and points corresponding to each film thickness of FIGS. 5(a) to (c) are plotted in FIG. 5(d).

As shown by the symbol (a) in FIG. 5(d), when the thickness of the first measurement electrode 301 is thick, the resistance value of the first measurement electrode 301 is low. Then, by performing virtual kogation removal, the surface of the first measurement electrode 301 dissolves into the ink and the thickness of the first measurement electrode 301 becomes thinner, and as shown by the symbols (b) and (c) in FIG. 5(d), the resistance value of the first measurement electrode 301 increases. Virtual kogation removal and resistance value measurement are performed alternately, and the time until the resistance value reaches a certain value or more is measured, and the information on that time is stored in memory 310.

For example, if the first measurement electrode 301 is formed so that it is entirely in contact with the liquid, continued application of a potential will cause the first measurement electrode 301 to dissolve, resulting in an extremely high resistance value, or in a so-called open state. A means for measuring time (time measurement means) measures the time until the open state is reached, and a writing means stores information about the measured time in memory. Note that the measuring means for measuring the resistance value, the time measurement means for measuring the time, and the writing means for writing information into memory may be located inside or outside the head.

The conditions for virtual kogation removal are preferably the same as the conditions for kogation removal when the head is actually driven. Virtual kogation removal may be performed using a direct current or a pulse. If the conditions for virtual kogation removal are the same as the conditions for kogation removal when the head is actually driven, the time measured by the time measurement means described above will be the time for which kogation removal is possible when the head is actually driven. This virtual kogation removal can be performed, for example, during electrical testing before the head (or recording device) is shipped. This results in a head with information about the time for which kogation removal can be performed stored in memory for each head. Another timing for performing virtual kogation removal is when the head is in the initial state immediately after it is attached to the recording device main body.

The conditions for virtual kogation removal before shipment, etc. may be changed from the conditions for kogation removal when the head is actually driven. In this case, the time difference due to different conditions in the time required for the resistance value to change by a specified amount is understood, and a correction based on this time difference (such as adding the difference) is made, thereby estimating the time in which kogation removal can be performed when the head is actually driven. For example, when performing virtual kogation removal at 10 V or higher, while performing actual kogation removal at around 1 V to 3 V, the dissolution of the first measurement electrode 301 progresses significantly, and a correction corresponding to this will be necessary. In this way, by changing the conditions and making corrections accordingly, the time required for measurement by the measurement means can be shortened.

<Measurement Process for Measuring Time Available for Kognet Removal (First Measurement Process)>
6 is a flowchart showing the flow of a first measurement process as one of the measurement processes for measuring the time during which kogation removal can be performed by performing virtual kogation removal according to the present embodiment. Note that, unless otherwise specified, the process of each of the following steps is executed by the CPU of the recording device.

First, in step S601, virtual kogation removal is started at a predetermined voltage, and at the same time, measurement of the time during which virtual kogation removal is performed (virtual kogation removal execution time) is started. As described below, each process from S601 to S604 may be executed repeatedly in some cases, and the execution time of virtual kogation removal in this step is measured to obtain the cumulative execution time over such repetitions. After this step, virtual kogation removal is performed for a certain period of time. Note that hereinafter, "step S~" will be abbreviated to "S~".

In S602, the virtual kogation removal is terminated and the measurement of the execution time of the virtual kogation removal is stopped.

In S603, the resistance value is measured.

In S604, it is determined whether the resistance value obtained in the most recent step S603 is equal to or greater than a predetermined threshold value. If the determination result in this step is true, it is assumed that the film thickness has fallen below a predetermined thickness, and the process proceeds to S605. On the other hand, if the determination result in this step is false, the process returns to S601, and virtual kogation removal is performed again for a certain period of time. The predetermined threshold value used in this step may be determined using a table such as that shown in FIG. 5(d), and is stored in advance in memory.

In S605, information on the accumulated time for which virtual kogation removal has been performed on the first measurement electrode 301 is written to memory as information indicating to what extent kogation removal on the first electrode 121 can be performed (information on execution acceptability). The information written in this step is used when actually performing a recording operation, and it is determined whether the recording head has reached the end of its life, for example, based on the magnitude relationship between the accumulated time indicated by the information and the accumulated time for which kogation removal has actually been performed. By providing a notification based on the result of such a determination, it is possible to notify the user at an appropriate time that head replacement is necessary.

<Configuration in which a measuring means is provided for each type of liquid>
The electrochemical reaction during kogation removal varies depending on the material of the first electrode and the type of liquid. When one head is used, the first electrode is generally made of one material, but multiple types of liquid are often used. In particular, inks such as cyan, magenta, yellow, and black are often used, and the components contained in the liquid differ. Since the types of liquid differ in this way, the electrochemical reaction differs, and the time during which kogation removal can be performed may also differ. Therefore, it is preferable to provide at least one measuring means for each type of liquid.

Figure 7 shows only the cavity-resistant layer and memory 310 on the recording element substrate. The recording element substrate has four nozzle rows (not shown), and the heating resistors (not shown) and cavity-resistant layers are arranged accordingly. Each row corresponds to an ink color, and each row (each color) has a measurement means 300. Virtual kogation removal is performed for each row, and the time available for kogation removal is measured, and the time information obtained by this measurement is stored in memory 310.

<Measurement means arrangement: Configuration using the cavity-resistant layer on top of the dummy heating resistor>
In the recording element substrate, a dummy heating resistor and a cavity-resistant layer may be formed next to the heating resistor that actually ejects ink. The reason for this is, for example, that in an ejection port array, the heating resistor portion at the end of the array is used for heat retention when heat is more likely to escape than the heating resistor portion at the center of the array. Ink is not actually ejected in the area of this dummy heating resistor. Therefore, the cavity-resistant layer that exists on the dummy heating resistor can be used as part of the measurement means.

At the ends of the recording element substrate (upper and lower sides in Figure 7), there is a cavitation-resistant layer 340 that exists on top of the dummy heating resistors. In the area of this cavitation-resistant layer 340, ink is not ejected and cavitation does not occur, so the cavitation-resistant layer is not necessary from the standpoint of protection from impacts due to cavitation. However, by using such a cavitation-resistant layer 340 as a measurement means, there is no need to provide a new pattern for the measurement means.

<Effects of this embodiment>
According to this embodiment, even if there are various manufacturing variations between heads, it is possible to accurately grasp the number of times that appropriate kogation removal can be performed and set this for each head.

In addition, the number of times kogation removal can be performed, taking into account the film thickness, can be determined by a single measurement when the head is in its initial state. This eliminates the need for a process to check the remaining film thickness while the head is in use, making it possible to reduce dead time.

[Other embodiments]
<Method for estimating remaining film thickness using reflectance>
FIG. 8 is a cross-sectional view showing a recording element substrate 100 in which the remaining film thickness is estimated by using reflectance instead of resistance as a substrate for a liquid ejection head according to the present disclosure. As shown in FIG. 8, a reflectance measuring means 350 for measuring the reflectance of a first measurement electrode 301 included in the measuring means 300 is provided on the upper part of the recording element substrate 100. The reflectance measuring means 350 measures the reflectance of the first measurement electrode 301, and the remaining film thickness of the first measurement electrode 301 can be estimated based on the measured reflectance. The reflectance measuring means for measuring the reflectance, the time measuring means for measuring the time until the reflectance becomes equal to or less than a predetermined threshold, and the writing means for writing the time information obtained by the measurement into the memory may be located outside the head. For example, the recording device main body may have a means for optically measuring the reflectance. In this case, in electrical inspection before the head is shipped at the manufacturing factory, it is preferable to measure the reflectance in the same manner as the recording device main body.

As described above, the reflectance measuring means 350 measures the reflectance of the first measurement electrode 301 based on the amount of light reflected by the first measurement electrode 301 by irradiating light from the upper part of the discharge port, and the film thickness is estimated based on the reflectance obtained by the measurement. For example, metal materials such as iridium used as a cavity-resistant layer have a relatively high reflectance. Therefore, when sufficient iridium remains, the reflectance is high. In contrast, when the iridium is dissolved and disappeared due to virtual kogation removal, the reflectance decreases because light is reflected by the insulating film layer and heating resistor below. By utilizing such a property, the reflectance is measured by the measuring means, and the film thickness of the first measurement electrode 301 after virtual kogation removal is performed can be estimated by using a table showing the correlation between reflectance and film thickness based on the measured reflectance. The above-mentioned table may be prepared in advance and stored in the memory of the recording device.

<Measurement Process for Measuring the Time Available for Kogation Removal Using Reflectance (Second Measurement Process)>
9 is a flowchart showing the flow of a second measurement process as one of the measurement processes for measuring the time during which kogation removal can be performed. Note that, unless otherwise specified, the process of each step below is executed by the CPU of the recording device.

First, in S901, virtual kogation removal is started at a predetermined voltage, and at the same time, measurement of the time during which virtual kogation removal is performed (virtual kogation removal execution time) is started. As described below, each process from S901 to S904 may be executed repeatedly in some cases, and the execution time in this step is measured to obtain the cumulative execution time over such repetitions. After this step, virtual kogation removal is performed for a certain period of time.

In S902, the virtual kogane removal is terminated and the measurement of the execution time of the virtual kogane removal is stopped.

In step S903, the reflectance is measured.

In S904, it is determined whether the reflectance obtained in the most recent S903 is equal to or less than a predetermined threshold. If the determination result in this step is true, it is assumed that the film thickness has fallen below a predetermined thickness, and the process proceeds to S905. On the other hand, if the determination result in this step is false, the process returns to S901, and virtual kogation removal is performed again for a certain period of time.

In S905, information on the execution time (accumulated time) of the virtual kogation removal is written to memory.

<Method for estimating remaining film thickness using the number of times virtual kogation removal is performed>
In the above embodiment, the cumulative value of the time during which virtual kogation removal was performed was used (FIG. 6, S601->S604 NO->S601), but the cumulative value of the number of times virtual kogation removal was performed may also be used.

When performing kogation removal, it is often determined in advance how much kogation removal will be performed in one kogation removal session. Specifically, for example, one mode of kogation removal involves passing a direct current for 30 seconds. In this mode, passing a direct current for 30 seconds constitutes one virtual kogation removal session, and the number of times the virtual kogation removal session is performed is counted and the count value information is recorded in memory.

Another form is to remove kogation by passing a current in pulses. Specifically, for example, one kogation removal is performed by applying 100 pulses. In this form, as with the above-mentioned form in which a direct current is passed for 30 seconds, one kogation removal is performed by applying 100 pulses, and the number of times virtual kogation removal is performed is counted and the information on this count value is recorded in memory.

<Measurement Process for Measure the Number of Times Kognetization Removal Can Be Executed (Third Measurement Process)>
10 is a flowchart showing the flow of a third measurement process, which is one of the measurement processes for measuring the number of times that kogation removal can be performed. Note that, unless otherwise specified, the process of each of the following steps is executed by the CPU of the recording device.

First, in S1001, the number of times kogation removal is performed is counted. As described below, each process of S1001 to S1004 may be executed repeatedly in some cases, and the count in this step is performed to obtain a cumulative count value across such repetitions. The initial value of the count value is 0, and 1 is added each time S1002 and S1003 are executed.

In S1002, virtual kogation removal is started at a predetermined voltage. After this step, virtual kogation removal is performed for a certain period of time.

In S1003, virtual kogation removal is completed.

In S1004, the resistance value is measured.

In S1005, it is determined whether the resistance value obtained in the most recent step S1004 is equal to or greater than a predetermined threshold value. If the determination result in this step is true, it is assumed that the film thickness has fallen below a predetermined thickness, and the process proceeds to S1006. On the other hand, if the determination result in this step is false, the process returns to S1002, and virtual kogation removal is performed again for a certain period of time. The predetermined threshold value used in this step may be determined using a table such as that shown in FIG. 5(d), and is stored in advance in memory.

In S1006, the count value information of the number of times kogation removal has been performed is written to memory.

<Measurement Process for Measure the Number of Times Kognation Removal Can Be Executed (Fourth Measurement Process)>
11 is a flowchart showing the flow of a fourth measurement process as one of the measurement processes for measuring the number of times that kogation removal can be performed. Note that, unless otherwise specified, the process of each of the following steps is executed by the CPU of the recording device.

First, in S1101, the number of times kogation removal is performed is counted. As described below, each process of S1101 to S1104 may be executed repeatedly in some cases, and the count in this step is performed to obtain a cumulative count value across such repetitions. The initial value of the count value is 0, and 1 is added each time S1102 and S1103 are executed.

In S1102, virtual kogation removal is started at a predetermined voltage. After this step, virtual kogation removal is performed for a certain period of time.

In S1103, virtual kogation removal is completed.

In step S1104, the reflectance is measured.

In S1105, it is determined whether the reflectance obtained in the most recent S1104 is equal to or less than a predetermined threshold. If the determination result in this step is true, it is assumed that the film thickness has fallen below a predetermined thickness, and the process proceeds to S1106. On the other hand, if the determination result in this step is false, the process returns to S1102, and virtual kogation removal is performed again for a certain period of time.

In S1106, the count value information of the number of times kogation removal has been performed is written to memory.

<Method for estimating remaining film thickness by image recognition>
In the above embodiment, the film thickness of the first measurement electrode 301 included in the measuring means 300 is estimated using the resistance value or reflectance, but the film thickness may be estimated based on an image. For example, it is possible to photograph the appearance of the first measurement electrode 301 on the recording element substrate and estimate the film thickness from the photographed image. In more detail, when the pixel values of each pixel constituting the photographed image are binarized, the remaining parts of the metal material such as iridium used as the cavity-resistant layer become white. By appropriately setting the threshold value for binarization, it is possible to make the remaining film thickness white (pixel value 0) and the remaining film thickness black (pixel value 1) when the film thickness is equal to or less than a predetermined threshold.

The imaging means for photographing the external appearance of the first measurement electrode 301 may be mounted on the recording device body. Such imaging means may also be installed in the head manufacturing factory.

<Line head: When there are multiple chips for one type of ink>
In a line head, multiple chips are mounted on one head, and each chip ejects one color ink. For each ink color corresponding to each chip, an ejection port 171, a liquid chamber 172, a heating resistor 150, a protective layer, a first electrode 121, a second electrode 122, and a measuring means 300 are provided. Note that it is sufficient for the memory 310 to have one memory for storing information on all the chips.

The lifespan of such a head is determined according to the shortest lifespan of all the chips. In other words, the lifespan of the head is equal to the lifespan of the shortest lifespan of all the chips. For this reason, it is preferable to provide at least one measuring means 300 for each of the multiple chips. It is also preferable to count the number of times that kogation removal can be performed for each chip and store information on the smallest count value in memory.

The present disclosure can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[Technical Features of the Present Disclosure]
The present disclosure includes the following configurations.

(Configuration 1) A liquid ejection head comprising: an ejection port for ejecting liquid; a liquid chamber communicating with the ejection port; a heat generating element for generating the energy required for ejecting the liquid; a protective layer for blocking contact between the heat generating element and the liquid; a first electrode arranged on the protective layer so as to cover at least the heat generating element and made of a material containing a metal that dissolves by an electrochemical reaction with the liquid; a second electrode arranged so as to be electrically connected to the first electrode via the liquid inside the liquid chamber and for inducing the electrochemical reaction; a measuring means used to measure a value related to the film thickness of the first electrode and to measure information related to the permissibility of kogation removal to be performed on the first electrode; and a memory for storing the information.

(Configuration 2) The liquid ejection head described in configuration 1, wherein the measurement means includes a first measurement electrode and a second measurement electrode, the first measurement electrode being formed in the same pattern as the first electrode, and the second measurement electrode being formed in the same pattern as the second electrode.

(Configuration 3) A liquid ejection head according to configuration 1 or 2, in which the value relating to the film thickness of the first electrode is the resistance value of the first measurement electrode, and the information is measured as the time until the resistance value becomes equal to or greater than a predetermined threshold value by performing virtual kogne removal on the first measurement electrode.

(Configuration 4) A liquid ejection head according to any one of configurations 1 to 3, in which the value relating to the film thickness of the first electrode is the reflectance of the first measurement electrode, and the information is measured as the time it takes for the reflectance to fall below a predetermined threshold value by performing virtual kogne removal on the first measurement electrode.

(Configuration 5)
A liquid ejection head described in any one of configurations 1 to 4, wherein the value relating to the film thickness of the first electrode is the resistance value of the first measurement electrode, and the information is the number of times that virtual kogane removal is performed on the first measurement electrode until the resistance value becomes equal to or greater than a predetermined threshold value.

(Configuration 6) A liquid ejection head according to any one of configurations 1 to 5, in which the value relating to the film thickness of the first electrode is the reflectance of the first measurement electrode, and the information is the number of times that virtual kogation removal is performed on the first measurement electrode until the reflectance becomes equal to or less than a predetermined threshold value.

(Configuration 7) A liquid ejection head according to any one of configurations 1 to 6, in which multiple types of liquid are used as the liquid, and the measuring means is provided for each type of liquid.

(Configuration 8) A liquid ejection head according to any one of configurations 1 to 7, in which a plurality of chips each having the ejection port, the liquid chamber, the heat generating element, the protective layer, the first electrode, the second electrode, and the measuring means are mounted.

(Configuration 9) A liquid ejection head according to any one of configurations 1 to 8, in which the pixel values of each pixel constituting a captured image of the appearance of the first measurement electrode portion are binarized using a predetermined threshold value.

(Configuration 10) A liquid ejection head having an ejection port for ejecting liquid, a liquid chamber communicating with the ejection port, a heat generating element for generating the energy required for ejecting the liquid, a protective layer for blocking contact between the heat generating element and the liquid, a first electrode arranged on the protective layer so as to cover at least the heat generating element and made of a material containing a metal that dissolves by an electrochemical reaction with the liquid, a second electrode provided so as to be electrically connectable with the first electrode via the liquid inside the liquid chamber and for generating the electrochemical reaction, and a memory, and a control means for measuring a value related to the film thickness of the first electrode, measuring information related to the permissibility of performing kogation removal on the first electrode, and storing the information in the memory.

(Configuration 11) A method for controlling a liquid ejection head having an ejection port for ejecting liquid, a liquid chamber communicating with the ejection port, a heat generating element for generating the energy required for ejecting the liquid, a protective layer for blocking contact between the heat generating element and the liquid, a first electrode arranged on the protective layer so as to cover at least the heat generating element and made of a material containing a metal that dissolves by an electrochemical reaction with the liquid, and a second electrode arranged to be electrically connected to the first electrode via the liquid inside the liquid chamber and for generating the electrochemical reaction, the method comprising the steps of measuring a value related to the film thickness of the first electrode, and measuring information regarding the permissibility of kogation removal to be performed on the first electrode, and storing the information in a memory.

(Configuration 12) The control method described in Configuration 11, further comprising a step of determining whether the liquid ejection head has reached the end of its life using the information.

(Configuration 13) A program for causing a computer to execute the method described in Configuration 11.

121 First electrode 122 Second electrode 150 Heating resistor 171 Discharge port 172 Liquid chamber 300 Measuring means 310 Memory

Claims (13)

A discharge port for discharging a liquid;
a liquid chamber communicating with the discharge port;
a heating element for generating energy required for discharging the liquid;
a protective layer for blocking contact between the heat generating element and the liquid;
a first electrode disposed on the protective layer so as to cover at least the heat generating element, the first electrode being made of a material containing a metal that dissolves by an electrochemical reaction with the liquid;
a second electrode provided to be electrically connectable to the first electrode via the liquid in the liquid chamber, the second electrode causing the electrochemical reaction;
a measuring means for measuring a value related to a film thickness of the first electrode and measuring information related to the permissibility of performing kogation removal on the first electrode;
A memory for storing said information;
having
A liquid ejection head comprising: the measuring means includes a first measurement electrode and a second measurement electrode,
The first measurement electrode is formed in the same pattern as the first electrode,
The second measurement electrode is formed in the same pattern as the second electrode.
The liquid ejection head according to claim 1 . the value relating to the film thickness of the first electrode is a resistance value of the first measurement electrode,
As the information, a time until the resistance value becomes equal to or greater than a predetermined threshold value due to execution of virtual kogation removal for the first measurement electrode is measured.
The liquid ejection head according to claim 2 . the value relating to the film thickness of the first electrode is the reflectance of the first measurement electrode,
As the information, a time until the reflectance becomes equal to or less than a predetermined threshold value due to execution of virtual kogation removal on the first measurement electrode is measured.
The liquid ejection head according to claim 2 . the value relating to the film thickness of the first electrode is a resistance value of the first measurement electrode,
As the information, the number of times the virtual kogation removal is performed on the first measurement electrode until the resistance value becomes equal to or greater than a predetermined threshold value is measured.
The liquid ejection head according to claim 2 . the value relating to the film thickness of the first electrode is the reflectance of the first measurement electrode,
As the information, the number of times the virtual kogation removal is performed on the first measurement electrode until the reflectance becomes equal to or lower than a predetermined threshold is measured.
The liquid ejection head according to claim 2 . As the liquid, a plurality of types of liquid are used,
The measuring means is provided for each type of liquid.
3. The liquid ejection head according to claim 1 or 2. a plurality of chips each having the ejection port, the liquid chamber, the heat generating element, the protective layer, the first electrode, the second electrode, and the measuring means are mounted;
3. The liquid ejection head according to claim 1 or 2. A pixel value of each pixel constituting a photographed image of the appearance of the portion of the first measurement electrode is binarized using a predetermined threshold value.
The liquid ejection head according to claim 2 . A discharge port for discharging a liquid;
a liquid chamber communicating with the discharge port;
a heating element for generating energy required for discharging the liquid;
a protective layer for blocking contact between the heat generating element and the liquid;
a first electrode disposed on the protective layer so as to cover at least the heat generating element, the first electrode being made of a material containing a metal that dissolves by an electrochemical reaction with the liquid;
a second electrode provided to be electrically connectable to the first electrode via the liquid in the liquid chamber, the second electrode causing the electrochemical reaction;
Memory,
A liquid ejection head having
and a control means for measuring a value related to a film thickness of the first electrode, measuring information related to the permissibility of performing kogation removal on the first electrode, and storing the information in the memory.
having
A liquid ejection device comprising: A discharge port for discharging a liquid;
a liquid chamber communicating with the discharge port;
a heating element for generating energy required for discharging the liquid;
a protective layer for blocking contact between the heat generating element and the liquid;
a first electrode disposed on the protective layer so as to cover at least the heat generating element, the first electrode being made of a material containing a metal that dissolves by an electrochemical reaction with the liquid;
a second electrode provided to be electrically connectable to the first electrode via the liquid in the liquid chamber, the second electrode causing the electrochemical reaction;
A method for controlling a liquid ejection head comprising:
measuring a value related to a film thickness of the first electrode and measuring information related to the permissibility of performing kogation removal on the first electrode;
storing said information in a memory;
having
A control method comprising: The method further includes a step of determining whether the liquid ejection head has reached the end of its life using the information.
The control method according to claim 11. A program for causing a computer to execute the method according to claim 11.

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