JP7643066B2 - Liquid ejection device, liquid ejection method, and liquid ejection device for battery components - Google Patents

Description

The present invention relates to a liquid ejection device, a liquid ejection method, and a liquid ejection device for battery components.

Conventionally, liquid ejection devices are known that eject and apply liquid onto an ejection receiving medium transported in a predetermined transport direction to form an ejection receiving area.

In addition, for the purpose of reducing the amount of liquid consumed during maintenance, etc., a configuration has been disclosed in which a test waveform drive signal is applied to the recording head when drawing and recording a desired image on a recording medium, and at least one of the voltage, frequency, and waveform shape is changed from the recording waveform drive signal applied to the recording head, thereby ejecting with a greater ejection force than when the recording waveform drive signal is applied, thereby forming a test pattern (see, for example, Patent Document 1).

However, with the configuration of Patent Document 1, there was a concern that if the drive signal was switched while an image was being formed on the recording medium, the quality of the ejected area that was formed would decrease.

The present invention aims to prevent deterioration in the quality of the ejected area that is formed.

A liquid ejection device according to one aspect of the present invention is a liquid ejection device that ejects and applies liquid onto an ejection receiving medium transported in a predetermined transport direction to form an ejection receiving region, and includes a plurality of liquid ejection units capable of ejecting the liquid based on a drive waveform, an output unit capable of outputting the drive waveform to each of the plurality of liquid ejection units, an acquisition unit that acquires information indicating properties of the liquid, and a switching unit that switches the drive waveform based on the properties, the plurality of liquid ejection units including a first liquid ejection unit and a second liquid ejection unit that is disposed at a position different from the first liquid ejection unit along the transport direction, and the positions on the ejection receiving medium where the liquid is applied by each of the first liquid ejection unit and the second liquid ejection unit when the properties satisfy a predetermined condition are spaced apart along the transport direction.

The present invention makes it possible to suppress deterioration in the quality of the ejected area that is formed.

1 is a diagram showing an example of the configuration of a film forming apparatus according to an embodiment; 3A and 3B are diagrams illustrating an example of the configuration of an ink ejection unit according to the embodiment. FIG. 4 is a block diagram of an example of a functional configuration of a control unit according to the embodiment. 11 is a flowchart of an example of processing by a control unit according to the embodiment. FIG. 11 is a diagram showing an example of temperature change of ink over film formation time. 6A and 6B are diagrams showing examples of driving waveforms, in which FIG. 6A shows a diagram before switching, and FIG. 6B shows a diagram after switching. 7A and 7B are diagrams showing an example of change in ink application state due to switching of driving waveforms, with FIG. 7A being a comparative example and FIG. 7B being a diagram of this embodiment.

Below, a description of the embodiment of the invention will be given with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicate descriptions will be omitted as appropriate.

The embodiments shown below are illustrative of a liquid ejection device for embodying the technical concept of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended as examples, and are not intended to limit the scope of the present invention thereto. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity of explanation.

The liquid ejection device according to the embodiment ejects and applies liquid onto an ejection receiving medium that is transported in a predetermined transport direction, thereby forming an ejection receiving area.

The ejection receiving medium includes, for example, an electrode substrate (current collector) used in an electricity storage device such as a battery, a power generation device such as a fuel cell, a solar power generation device, etc., and also includes an electrode in which an electrode material layer such as an active material is formed on an electrode substrate. The liquid ejection device applies a liquid in which various materials, including a powdered active material or a catalyst composition, are dispersed in a liquid to the ejection receiving medium, and then fixes and dries the liquid to form an ejection receiving region such as an electrode having a film containing the various materials on the ejection receiving medium.

When such a liquid ejection device ejects liquid continuously for a long period of time, the properties of the liquid may change due to temperature changes in the ejected liquid, etc. Here, the properties of the liquid refer to the nature or state of the liquid. The properties of the liquid include the physical properties of the liquid, such as the viscosity or surface tension of the liquid.

The drive waveform that drives the liquid ejection unit of a liquid ejection device is often adjusted to match the properties of the liquid so that the liquid is ejected properly without ejection abnormalities such as non-ejection or deflected ejection. However, if the properties of the liquid change due to continuous ejection over a long period of time, the drive waveform may no longer match, and the liquid may no longer be ejected properly.

In this case, it is preferable to store multiple drive waveform data adjusted for different liquid properties in advance in a storage unit or the like, and to make it possible to switch the drive waveform using the stored drive waveform data in response to changes in the liquid properties.

However, if the drive waveform is switched while forming the ejected area, the ejection characteristics change transiently, resulting in abnormal areas, which can degrade the quality of the ejected area that is formed. These abnormal areas include streak areas, which are areas where the amount of ejected liquid differs from the surrounding area and extends in a streak-like pattern.

For example, when a liquid ejection device includes multiple liquid ejection units arranged along the transport direction and the drive waveform for ejecting from each of the multiple liquid ejection units is switched, the liquid ejected in a state where the ejection characteristics have changed transiently concentrates at a specific position along the transport direction on the ejection receiving medium, making the abnormal area more noticeable. As a result, the quality of the ejection receiving area that is formed deteriorates.

In an embodiment, the liquid ejection device includes a plurality of liquid ejection units capable of ejecting liquid based on a drive waveform, an output unit capable of outputting a drive waveform to each of the plurality of liquid ejection units, an acquisition unit that acquires information indicating the properties of the liquid, and a switching unit that switches the drive waveform based on the properties of the liquid.

The multiple liquid ejection units include a first liquid ejection unit and a second liquid ejection unit that is arranged at a position different from the first liquid ejection unit along the transport direction, and when the properties of the liquid satisfy a predetermined condition on the ejection medium, the positions at which the liquid is applied by each of the first liquid ejection unit and the second liquid ejection unit are spaced apart along the transport direction.

For example, the switching unit switches between the drive waveforms output to the first liquid ejection unit and the second liquid ejection unit when the liquid properties satisfy a predetermined condition. The liquid properties are the liquid temperature, etc., and the predetermined condition is satisfied when the liquid temperature changes to a predetermined threshold value or more.

Also, "separate" means that the centers of the liquids are separated, and in this embodiment, it specifically means that they are not adjacent to each other. However, as long as the centers of the liquids are separated, it is not necessary that some of the liquids are separated.

As a result, when the drive waveform is switched, the liquid ejected in a state in which the ejection characteristics of the first liquid ejection unit and the second liquid ejection unit change transiently is dispersed apart along the transport direction. As a result, the number of abnormal areas formed is reduced, making it possible to suppress deterioration in the quality of the ejected areas.

The following describes an embodiment using as an example a film forming device that forms a film on a non-permeable substrate by ejecting ink onto the substrate. Here, the substrate is an example of a medium to be ejected, ink is an example of a liquid, the film is an example of a region to be ejected, and the film forming device is an example of a liquid ejection device.

[Embodiment]
<Overall configuration example of film forming apparatus 100>
First, the overall configuration of the film forming apparatus 100 will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating an example of the overall configuration of the film forming apparatus 100. Fig. 1 shows the inside of the film forming apparatus 100 seen through from a direction substantially perpendicular to a conveying direction 20 of a material 2 to be coated.

As shown in FIG. 1, the film forming device 100 has an unwinding section 1, an application section 3, a curing section 4, a drying section 5, a winding section 6, and a control section 7. The application section 3 also has ink ejection sections 30a, 30b, 30c, and 30d.

The film forming device 100 conveys the workpiece 2 along the conveying direction 20 using the unwinding section 1 and the winding section 6, while applying ink ejected from each of the ink ejection sections 30a, 30b, 30c, and 30d included in the application section 3 onto the workpiece 2. The film forming device 100 forms a continuous, uniform film on the workpiece 2 by irradiating the ink applied onto the workpiece 2 with ultraviolet light using the curing section 4 to harden it, and by blowing warm air into the drying section 5 to dry it.

The unwinding section 1 rotates the unwinding roll 11, which can rotate with the material 2 wound around it, and unwinds the material 2 wound around the roll, thereby running and transporting the material 2 from the unwinding section 1 to the coating section 3. The winding section 6 winds the material 2 around the rotated winding roll 61 and winds it up, thereby running and transporting the material 2 from the drying section 5 to the winding section 6.

In addition to the unwinding section 1 and the winding section 6, conveying rollers and the like not indicated with a reference number are also used as conveying means for conveying the material to be coated 2. The conveying rollers, the unwinding section 1, and the winding means constitute the conveying means for the material to be coated 2.

The material 2 to be coated is continuous along the conveying direction 20. The film forming device 100 conveys the material 2 to be coated along the conveying path between the unwinding section 1 and the winding section 6. The length of the material 2 to be coated along the conveying direction 20 is at least longer than the conveying path between the unwinding section 1 and the winding section 6. The film forming device 100 is capable of continuously forming a film on the material 2 to be coated that is continuous along the conveying direction 20.

The ink is composed of a liquid that realizes the function of a film. There are no particular limitations as long as the ink ejection section has a viscosity and surface tension that allows it to be ejected, but it is preferable that the viscosity is 30 mPa·s or less at room temperature and pressure, or when heated or cooled.

More specifically, these include solutions, suspensions, emulsions, etc. that contain solvents such as water and organic solvents, electrode materials such as dyes, pigments, and active materials, functionalizing materials such as polymerizable compounds, resins, and surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural dyes. These can be used, for example, as printing inks, surface treatment liquids, components of electronic elements and light-emitting elements, and liquids for forming various devices such as electronic circuit resist patterns.

The coating unit 3 applies the ink ejected by each of the ink ejection units 30a, 30b, 30c, and 30d onto the workpiece 2. The coating unit 3 is provided with the ink ejection units 30a, 30b, 30c, and 30d along the transport direction 20 of the workpiece 2. However, this is not limited to this, and the coating unit 3 can be provided with two or more ink ejection units along the transport direction 20.

In addition, since the ink ejection units 30a, 30b, 30c, and 30d have the same configuration, they will be collectively referred to as the ink ejection unit 30 unless otherwise specified. In addition, in this embodiment, the ink ejection units 30a, 30b, 30c, and 30d eject the same type of ink.

The ink ejection unit 30 has multiple nozzle rows in which multiple nozzles are arranged. The film forming device 100 is provided with the ink ejection unit 30 so that the ejection direction of the ink ejected from the nozzles is toward the workpiece 2. Each of the ink ejection units 30a, 30b, 30c, and 30d is an example of a plurality of liquid ejection units capable of ejecting ink based on a drive waveform.

The material to be coated 2 may be a non-permeable substrate such as a metal sheet on which a layer mainly made of particles is provided. The layer mainly made of particles provided on the non-permeable substrate may be, for example, a graphite layer.

Non-permeable substrates include metal sheets such as aluminum, copper, stainless steel, nickel, and platinum, and resin films such as polypropylene film, polyethylene terephthalate film, and nylon film.

The curing unit 4 has light sources 40a and 40b. When the light sources 40a and 40b are not distinguished, they are collectively referred to as light source 40. The light source 40 has a curing function of irradiating the ink applied on the substrate 2 with ultraviolet light to cure the ink layer into a resin layer.

As the light source 40, for example, a mercury lamp such as a low-, medium-, or high-pressure mercury lamp, a tungsten lamp, an arc lamp, an excimer lamp, an excimer laser, a semiconductor laser, a high-output UV-LED, a YAG laser, a laser system combining a laser with a nonlinear optical crystal, a high-frequency induced ultraviolet generator, an electron beam irradiation device such as EB cure, an X-ray irradiation device, etc. can be used. Among these, it is preferable to use a high-frequency induced ultraviolet generator, a high- or low-pressure mercury lamp, a semiconductor laser, etc., in order to simplify the system. In addition, a focusing mirror and a scanning optical system may be provided in the light source 40.

The drying section 5 has heaters 50a, 50b, and 50c. When heaters 50a, 50b, and 50c are not distinguished from one another, they are collectively referred to as heater 50. The heater 50 heats the ink formed on the substrate 2 to dry the remaining solvent in the ink, and functions as a curing or drying means or a heating or heating mechanism that promotes curing or dries the ink.

The heater 50 can be, for example, an infrared lamp, a roller with a built-in heating element (heat roller), a blower that blows out warm or hot air, or a furnace that introduces boiler-type hot air using water vapor, etc.

The control unit 7 is a control device that controls the entire film forming apparatus 100. There are no particular limitations on the location where the control unit 7 is located, and it can be determined appropriately.

<Configuration example of ink ejection unit 30>
Next, Fig. 2 is a diagram for explaining an example of the configuration of the ink ejection unit 30. Fig. 2 is a diagram showing the ink ejection units 30a, 30b, 30c, and 30d as viewed from the ink ejection direction side. The material 2 to be coated is transported along the transport direction 20 while facing the ink ejection units 30a, 30b, 30c, and 30d.

The ink ejection unit 30 is a line-type ink ejection unit. A "line-type ink ejection unit" is one in which nozzles that eject ink are arranged across the entire width of the material 2 in the width direction (the direction perpendicular to the transport direction 20).

As shown in FIG. 2, each of the ink ejection units 30a, 30b, 30c, and 30d has four inkjet heads 9 arranged in a direction substantially perpendicular to the transport direction 20. The inkjet head 9 is an example of a liquid ejection head. The inkjet head 9 is also a general term for the four inkjet heads. The inkjet head 9 has multiple nozzles 10 arranged in a direction substantially perpendicular to the transport direction 20, and ejects ink from each of the multiple nozzles 10.

Four inkjet heads 9 each having a plurality of nozzles 10 are arranged in a direction substantially perpendicular to the transport direction 20, so that ink can be ejected across the entire width of the workpiece 2. Note that while FIG. 2 illustrates an example of a configuration in which one ink ejection section 30 has four inkjet heads 9, it is sufficient for the ink ejection section 30 to have at least one inkjet head 9. Note that the width of the ink ejection section 30 does not necessarily have to be the entire width of the workpiece 2, and can be determined as appropriate.

In the inkjet head 9, the means for applying a stimulus to the ink to eject the ink can be appropriately selected according to the purpose, and for example, a pressure device, a piezoelectric element, a vibration generator, an ultrasonic oscillator, a light, etc. can be used. Specifically, there are piezoelectric actuators such as piezoelectric elements, shape memory alloy actuators that use a metal phase change due to temperature change, and electrostatic actuators that use electrostatic force.

Among these, the most preferable is one that applies a voltage to a piezoelectric element attached to a position called a pressure chamber (also called a liquid chamber, etc.) inside the ink flow path inside the inkjet head 9. In this inkjet head 9, the application of a voltage causes the piezoelectric element to bend, reducing the volume of the pressure chamber, thereby pressurizing the ink in the pressure chamber and ejecting the ink as droplets from the nozzle.

The ink ejection section 30 includes an inkjet ejection unit. The inkjet ejection unit is a collection of functional parts and mechanisms related to the ejection of ink from the ink ejection section 30. The inkjet ejection unit includes at least one of the following components: a supply mechanism, a maintenance and recovery mechanism, and a liquid ejection head movement mechanism, combined with the ink ejection section 30.

<Example of functional configuration of control unit 7>
Next, the functional configuration of the control unit 7 will be described with reference to Fig. 3. The control unit 7 executes a process of switching the drive waveform based on the temperature of the ink held inside and ejected by the ink ejection unit 30.

As shown in FIG. 3, the control unit 7 has an acquisition unit 71, a drive waveform storage unit 72, a drive waveform retention unit 73, an output unit 74, a switching unit 75, and an amplifier unit 76. Of these, the functions of the output unit 74, the switching unit 75, and the amplifier unit 76 are realized by electric circuits, and some of these functions can also be realized by software (CPU; Central Processing Unit). These functions may also be realized by multiple circuits or multiple pieces of software.

The function of the drive waveform storage unit 72 is realized by a non-volatile storage device such as a hard disk drive (HDD), and the function of the drive waveform retention unit 73 is realized by a volatile storage device such as a random access memory (RAM).

The acquisition unit 71 acquires temperature information of the ink ejected by the ink ejection unit 30 based on the resistance value input from the thermistor 31 provided in the ink ejection unit 30. The temperature of the ink is an example of a property of the liquid. The thermistor 31 is also an example of a detection unit that detects the temperature of the liquid.

The thermistor 31 is provided in each of the four inkjet heads 9 of the ink ejection unit 30, and its resistance value changes depending on the temperature of the inkjet head 9. The temperature of the inkjet head 9 is approximately equal to the temperature of the ink contained therein, and ink temperature information can be obtained from the resistance value output by the thermistor 31.

The acquisition unit 71 acquires ink temperature information from the resistance value output by at least one of the thermistors 31 provided in each of the four inkjets 9. Alternatively, the ink temperature information may be acquired from the average value of the resistance values output by two or more thermistors 31.

The drive waveform storage unit 72 stores drive waveform data that has been adjusted in advance so that the ink ejection unit 30 can eject ink appropriately. The drive waveform is a drive voltage signal that is applied to the ink ejection unit 30 and includes a waveform that causes the ink ejection unit 30 to eject ink. The drive waveform data is data that indicates the drive waveform.

The drive waveform for causing the ink ejection unit 30 to eject ink appropriately varies depending on the temperature of the ink, so the drive waveform storage unit 72 stores drive waveform data for multiple drive waveforms that have been pre-adjusted for each ink temperature.

The drive waveform storage unit 73 functions as a buffer that stores some of the multiple drive waveform data stored in the drive waveform storage unit 72. The drive waveform storage unit 73 has memory areas A and B, and acquires drive waveform data corresponding to changes in ink temperature from the drive waveform storage unit 72 and stores it in each of the memory areas A and B.

For example, the drive waveform storage unit 73 stores the drive waveform data before switching in one of the memory areas A and B, and stores the drive waveform data after switching in the other. Then, the drive waveform data stored in each of the memory areas A and B is updated as needed in response to changes in the ink temperature.

The output unit 74 can output to the ink ejection unit 30 a drive waveform generated based on the drive waveform data stored by the drive waveform storage unit 73 in each of memory areas A and B. The output unit 74 can output the drive waveforms before and after switching in parallel to each of the ink ejection units 30a, 30b, 30c, and 30d.

The switching unit 75 has a function of switching the drive waveform based on the ink temperature information. Specifically, the switching unit 75 switches based on the ink temperature indicated by the information input from the acquisition unit 71 so that either the pre-switching or post-switching drive waveform output by the output unit 74 is output to each of the ink ejection units 30a, 30b, 30c, and 30d via the amplification unit 76. The switching may be performed using a switch circuit or by software.

The switching unit 75 also switches the drive waveform at a timing when the positions where the ink ejected by each of the ink ejection units 30a, 30b, 30c, and 30d land on the workpiece 2 are separated along the transport direction 20. As a result, the ink ejected by each of the ink ejection units 30a, 30b, 30c, and 30d land on the workpiece 2 at positions separated along the transport direction 20 and are applied.

In other words, the position where the ink ejection unit 30a applies ink to the workpiece 2 when the drive waveform for ejecting ink from the ink ejection unit 30a is switched and the position where the ink ejection unit 30b applies ink to the workpiece 2 when the drive waveform for ejecting ink from the ink ejection unit 30b is switched are separated along the transport direction 20.

In this case, the ink ejection unit 30a corresponds to an example of a first liquid ejection unit, and the ink ejection unit 30b corresponds to an example of a second liquid ejection unit. However, this is not limited to this, and the first liquid ejection unit may be any of the ink ejection units 30a, 30b, 30c, and 30d, and the second liquid ejection unit may be any of the ink ejection units 30a, 30b, 30c, and 30d that is different from the first liquid ejection unit.

The amplifier unit 76 amplifies the drive waveform input from the switching unit 75 and outputs it to each of the ink ejection units 30a, 30b, 30c, and 30d.

The piezoelectric element 32 included in the ink ejection unit 30 inputs the drive waveform output by the amplifier 76. The piezoelectric element 32 expands and contracts in response to the drive waveform, applying positive or negative pressure to the ink in the liquid chamber. The ink ejection unit 30 can eject ink in response to the pressure applied by the piezoelectric element 32.

<Example of processing by control unit 7>
Next, the process by the control unit 7 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the process by the control unit 7. The process shown in Fig. 4 is triggered by the timing at which the control unit 7 receives an operation to start film formation by a user via an operation unit of the film forming apparatus 100 or the like.

First, in step S41, the acquisition unit 71 acquires information indicating the temperature of the ink ejected by the ink ejection unit 30 based on the resistance value input from the thermistor 31.

Next, in step S42, the switching unit 75 sets the ink temperature indicated by the information acquired by the acquisition unit 71 as a comparison value.

Next, in step S43, the drive waveform holding unit 73 acquires two of the multiple drive waveform data stored in the drive waveform storage unit 72 and holds them in memory areas A and B, respectively. For example, the drive waveform holding unit 73 holds the drive waveform data before switching that corresponds to the ink temperature, which is the comparison value, and is rising, in memory area A, and holds the drive waveform data after switching in memory area B. The drive waveform data after switching corresponds to the temperature closest to either the low temperature side or the high temperature side of the drive waveform data before switching.

Next, in step S44, the output unit 74 outputs to the ink ejection unit 30 the drive waveform generated based on the drive waveform data stored by the drive waveform storage unit 73 in each of memory areas A and B.

Next, in step S45, the acquisition unit 71 acquires information indicating the temperature of the ink ejected by the ink ejection unit 30 based on the resistance value input from the thermistor 31.

Next, in step S46, the switching unit 75 determines whether the ink temperature change is equal to or greater than a predetermined threshold. The ink temperature change is the difference between the ink temperature indicated by the information acquired by the acquisition unit 71 and the temperature set as the comparison value. After making the determination, the switching unit 75 updates the comparison value to the temperature indicated by the ink temperature information acquired by the acquisition unit 71.

If it is determined in step S46 that the threshold value is exceeded (step S46, Yes), the process proceeds to step S47; if it is determined that the threshold value is not exceeded (step S46, No), the process proceeds to step S49.

Next, in step S47, the switching unit 75 switches so that the post-switching drive waveform output by the output unit 74 is output to the ink ejection unit 30 via the amplifier unit 76.

Next, in step S48, the drive waveform storage unit 73 updates the drive waveform data it stores.

For example, the drive waveform storage unit 73 stores in memory area A the post-switching drive waveform data stored in memory area B. Then, when the temperature is rising (when the value obtained by subtracting the temperature before the change from the temperature after the change is a positive value), the drive waveform storage unit 73 acquires drive waveform data that is suitable for a temperature higher than the temperature for which the post-switching drive waveform data is suitable from the drive waveform storage unit 72 and stores it in memory area B. On the other hand, when the temperature is falling (when the value obtained by subtracting the temperature before the change from the temperature after the change is a negative value), the drive waveform storage unit 73 acquires drive waveform data that is suitable for a temperature lower than the temperature for which the post-switching drive waveform data is suitable from the drive waveform storage unit 72 and stores it in memory area B.

Next, in step S49, the control unit 7 determines whether or not to end the process.

If it is determined in step S49 that the process is to be terminated (step S49, Yes), the control unit 7 terminates the process, and if it is determined that the process is not to be terminated (step S, No), the control unit 7 repeats the process from step S44 onwards.

In this way, the control unit 7 can execute the process of switching the drive waveform based on the temperature information of the ink ejected by the ink ejection unit 30.

<Example of ink temperature change>
Next, a change in temperature of the ink discharged by the ink discharge unit 30 will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of a change in temperature of the ink over a film formation time.

When film formation is performed continuously for a long period of time, the temperature of the ink changes due to the influence of changes in the internal temperature of the film forming device 100 and heat generated by driving the inkjet head 9. Graph 51 shown in Figure 5 shows the change in ink temperature according to such film formation time.

The physical properties of the ink, such as its viscosity, change depending on the ink temperature, and the ejection characteristics change. For example, as the ink temperature rises, the ink viscosity decreases and the viscous resistance decreases, so if the same drive waveform as when the ink temperature is low is used, the ejection speed will be faster than desired. As a result, the landing position of the ejected ink on the substrate 2 will deviate from the desired position. In addition, the volume of the ejected ink droplets will be larger than desired, and the size and thickness of the dots formed by the ejected ink droplets landing on the substrate 2 will be larger. As a result, unevenness will occur in the ink applied to the substrate 2, and the quality of the film formed may be reduced.

For example, in applications where a liquid ejection device forms images at predetermined intervals on a substrate such as paper, it is possible to eliminate the effects of abnormal areas by switching the drive waveform using invalid areas such as between the images that are formed.

However, in applications where a uniform film is continuously formed on the workpiece 2, such as the film forming device 100 according to this embodiment, there are no invalid areas, so the invalid areas cannot be used to switch the drive waveform, and the effect of the abnormal areas becomes particularly noticeable.

Therefore, in this embodiment, the drive waveform can be switched depending on the ink temperature. The multiple horizontal bars shown on graph 51 represent the time range in which the same drive waveform is used. A number of drive waveforms corresponding to the number of horizontal bars adjusted according to the ink temperature are stored in drive waveform storage unit 72, and the drive waveform is switched depending on the ink temperature.

For example, the multiple stored drive waveforms are adjusted so that the ejection force decreases as the ink temperature increases. By switching the drive waveform according to the ink temperature, the ink ejection speed and droplet volume remain roughly constant regardless of the ink temperature.

For example, when the drive waveform corresponding to horizontal bar 53 switches to the drive waveform corresponding to horizontal bar 52, the drive waveform switches at almost the same timing as shown by timing 52a and timing 53b, so the ejection characteristics change transiently in response to the switching. As a result, abnormal areas such as streaks caused by changes in the ink ejection speed and density unevenness caused by changes in the volume of the ink droplets may occur. If the abnormal areas caused by the ink ejected by each of ink ejection units 30a, 30b, 30c, and 30d are concentrated in close positions along the transport direction 20, the abnormal areas become more noticeable.

In contrast, in this embodiment, when the drive waveform is switched, each of the ink ejection units 30a, 30b, 30c, and 30d applies ink to positions spaced apart along the transport direction 20 on the substrate 2. As a result, the positions of the abnormal areas are dispersed along the transport direction 20, and the abnormal areas are reduced compared to when abnormal areas caused by multiple ink ejection units are concentrated at close positions along the transport direction 20.

<Driving waveform example>
Next, the drive waveform will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the drive waveform. Fig. 6(a) shows the drive waveform before switching, and Fig. 6(b) shows the drive waveform after switching. The horizontal axis of Fig. 6 indicates time, and the vertical axis indicates potential.

As shown in FIG. 6(a), the driving waveform 33 before switching is an example of a first driving waveform that includes pulse waveforms P1a, P2a, and P3a. Pulse waveforms P1a and P2a are negative pressure waveforms that cause the ink ejection head to eject ink. Application of pulse waveforms P1a and P2a ejects two small droplets that merge in flight to become a medium-sized droplet. Pulse waveform P3a is a positive pressure waveform that has the function of suppressing vibrations that remain on the liquid surface after ejection.

The pulse interval Ta represents the time interval between the pulse waveform P1a and the pulse waveform P2a. The pulse width Δta represents the pulse width of the pulse waveform P2a. The falling time t1a represents the falling time included in the pulse waveform P2a, and the rising time t2a represents the falling time included in the pulse waveform P3a.

As shown in FIG. 6(b), the driving waveform 34 after switching is an example of a second driving waveform that includes pulse waveforms P1b, P2b, and P3b. Pulse waveforms P1b and P2b are negative pressure waveforms that cause the ink ejection head to eject ink. Application of pulse waveforms P1b and P2b ejects two small droplets that merge in flight to become a medium-sized droplet. Pulse waveform P3b is a positive pressure waveform that has the function of suppressing vibrations that remain on the liquid surface after ejection.

The pulse interval Tb represents the time interval between the pulse waveform P1b and the pulse waveform P2b. The pulse width Δtb represents the pulse width of the pulse waveform P2b. The falling time t1b represents the falling time included in the pulse waveform P2b, and the rising time t2b represents the falling time included in the pulse waveform P3b.

The potential difference V1 indicates the potential difference of the negative peak potential between the pulse waveform P1a and the pulse waveform P1b. The potential difference V2 indicates the potential difference of the negative peak potential between the pulse waveform P2a and the pulse waveform P2b.

Drive waveform 33 and drive waveform 34 have different peak potentials on the negative side of the pulse waveform so that potential differences V1 and V2 are generated. Compared to drive waveform 33, drive waveform 34 has a smaller peak potential on the negative side by the amount of potential differences V1 and V2, and has a smaller ejection force. When the ink changes from a low temperature to a high temperature, drive waveform 33 is switched to drive waveform 34, and the ejection force is reduced, thereby reducing changes in the ink ejection speed or ink droplet volume, etc., before and after the drive waveform is switched.

Although FIG. 6 shows an example in which the potential of the drive waveform is different, this is not limiting. The switching unit 75 may switch the drive waveform 33 to a drive waveform 34 that is different from the drive waveform 33 in at least one of the potential contained in the pulse waveform, the fall timing, the pulse width, the rise timing, and the time interval between multiple pulse waveforms. Which items to switch can be appropriately selected depending on the properties of the ink.

<Example of change in ink application state due to switching of driving waveform>
Fig. 7 is a diagram showing an example of a change in the ink application state due to switching of the drive waveform. Fig. 7(a) is a diagram showing a comparative example, and Fig. 7(b) is a diagram showing this embodiment. Fig. 7 shows a dot array formed by applying ink ejected from each of the ink ejection units 30a, 30b, 30c, and 30d onto the material to be coated 2. The dot array is formed by arranging dots of ink ejected from each nozzle of the ink ejection unit in a direction perpendicular to the transport direction 20.

In FIG. 7, each dot array is repeatedly applied along the transport direction 20. Dot arrays shown with the same type of hatching represent dot arrays produced by the same ink ejection unit.

The comparative example is a case where this embodiment is not applied.

In FIG. 7(a), dot array 35aX is formed with ink ejected by ink ejection unit 30a. Dot array 35bX is formed with ink ejected by ink ejection unit 30b. Dot array 35cX is formed with ink ejected by ink ejection unit 30c. Dot array 35dX is formed with ink ejected by ink ejection unit 30d.

Dot array 35aX' is formed from ink ejected by ink ejection unit 30a when the drive waveform is switched. Dot array 35bX' is formed from ink ejected by ink ejection unit 30b when the drive waveform is switched. Dot array 35cX' is formed from ink ejected by ink ejection unit 30c when the drive waveform is switched. Dot array 35dX' is formed from ink ejected by ink ejection unit 30d when the drive waveform is switched.

In dot arrays 35aX', 35bX', 35cX', and 35dX', the ink ejection characteristics change transiently when the drive waveform is switched, and the volume of the ejected ink droplets becomes smaller, resulting in smaller dots.

In the comparative example, as shown in region 701, dot arrays 35aX', 35bX', 35cX', and 35dX' are concentrated in close positions along the transport direction 20. As a result, the difference from the other regions is more noticeable.

On the other hand, in FIG. 7(b), dot array 35a is formed with ink ejected by ink ejection unit 30a. Dot array 35b is formed with ink ejected by ink ejection unit 30b. Dot array 35c is formed with ink ejected by ink ejection unit 30c. Dot array 35d is formed with ink ejected by ink ejection unit 30d.

Dot array 35a' is formed from ink ejected by ink ejection unit 30a when the drive waveform is switched. Dot array 35b' is formed from ink ejected by ink ejection unit 30b when the drive waveform is switched. Dot array 35c' is formed from ink ejected by ink ejection unit 30c when the drive waveform is switched. Dot array 35d' is formed from ink ejected by ink ejection unit 30d when the drive waveform is switched.

In dot arrays 35a', 35b', 35c', and 35d', the ink ejection characteristics change transiently when the drive waveform is switched, and the volume of the ejected ink droplets becomes smaller, resulting in smaller dots.

In this embodiment, the dot arrays 35a', 35bX', 35c', and 35d' are spaced apart along the transport direction 20. In other words, the dot arrays formed by the ink ejected by each of the ink ejection units 20a, 30b, 30c, and 30d when the drive waveform is switched are not adjacent to each other along the transport direction 20. As a result, compared to the dot arrays 35aX', 35bX', 35cX', and 35dX', there are fewer differences from other areas, and abnormal areas are reduced.

In addition, because there are dots made with the same type of ink nearby, the differences with other areas are further reduced due to the merging and leveling (averaging) effects of the same type of ink.

Note that in FIG. 7, dots formed with ink having a small droplet volume are shown as an example of abnormal regions, but abnormal regions are not limited to this. For example, when the ink ejection speed differs, the position of the dots shifts along the transport direction 20, resulting in a streaky region that extends in a direction approximately perpendicular to the transport direction 20. For this streaky region as well, the abnormal region mitigation effect can be obtained in the same manner as described above.

<Effects of the Film Forming Apparatus 100>
As described above, in this embodiment, the film forming apparatus 100 (liquid ejection apparatus) includes a plurality of ink ejection sections 30 (liquid ejection sections) capable of ejecting ink (liquid) based on a drive waveform, an output section 74 capable of outputting a drive waveform to each of the plurality of ink ejection sections 30, an acquisition section 71 that acquires information indicating the temperature (properties) of the ink, and a switching section 75 that switches the drive waveform based on the ink temperature.

The multiple ink ejection units 30 include an ink ejection unit 30a and an ink ejection unit 30b arranged at a position different from the ink ejection unit 30a along the transport direction, and when the temperature of the ink satisfies a predetermined condition on the coated material 2 (ejection medium), the positions at which ink is applied by each of the ink ejection units 30a and 30b are spaced apart along the transport direction 20.

The switching unit 75 switches between the drive waveforms output to the ink ejection units 30a and 30b when the temperature of the ink satisfies a predetermined condition. The predetermined condition is satisfied, for example, when the temperature of the liquid changes to or exceeds a predetermined threshold value.

As a result, when the drive waveform is switched, the ink ejected in a state in which the ejection characteristics of the ink ejection units 30a and 30b change transiently is dispersed along the transport direction 20. As a result, the number of abnormal areas formed is reduced, and deterioration in the quality of the film (ejected area) can be suppressed.

In this embodiment, each of the ink ejection units 30 includes four (multiple) inkjet heads (liquid ejection heads) arranged in a direction intersecting the transport direction 20. This allows a film to be formed over a wider area along the width direction of the material 2 to be coated.

In this embodiment, the drive waveform 33 includes pulse waveforms P1a and P2a, and the switching unit 75 switches the drive waveform 33 (first drive waveform) to a drive waveform 34 (second drive waveform) that is different from the drive waveform 33 in at least one of the potential, fall timing, pulse width, rise timing, and time interval between multiple pulse waveforms included in the pulse waveforms P1a and P2a. This allows the ink ejection unit 30 to eject ink appropriately in accordance with the properties such as the temperature.

Other Preferred Embodiments
In the above embodiment, the ink ejection units 30a, 30b, 30c, and 30d eject the same type of ink, but the present invention is not limited to this. When at least two or more ink ejection units 30 eject the same type of ink, the same effect as described above can be obtained.

In addition, although the configuration in which the drive waveform is switched for each of the ink ejection units 30a, 30b, 30c, and 30d has been exemplified, the present invention is not limited to this. The same effect as described above can be obtained even when the drive waveform is switched for each of the inkjet heads 9 included in each of the ink ejection units 30a, 30b, 30c, and 30d.

The timing of switching the drive waveform may be different for each ink ejection unit 30 or each inkjet head 9, or may be switched at approximately the same timing for all inkjet heads 9 of all ink ejection units 30. Since all inkjet heads 9 of all ink ejection units 30 are located at different positions, if the drive waveform is switched at approximately the same timing, the positions at which all inkjet heads 9 of all ink ejection units 30 apply ink will be spaced apart along the transport direction 20. As a result, the same effect as described above can be obtained.

In the above embodiment, the driving waveform is switched in response to changes in the ink temperature, but the same effect can be obtained when the driving waveform is switched in response to changes in other ink properties such as humidity or air pressure.

The film forming apparatus 100 shown in the above-described embodiment can be used for various purposes. For example, a film can be formed on a component contained in a battery such as a storage battery, using the component as the ejection medium.

The components that make up a battery are manufactured by stacking various films, such as electrode layers, insulating layers, and active material layers, and it is required to uniformly form a film that is uniform in thickness and free of internal defects. The film forming device 100 can form a film that reduces abnormal regions and suppresses quality degradation due to abnormal regions, making it particularly suitable for applications in which a film is formed on components that include batteries. The film forming device 100 is an example of a liquid ejection device for battery components.

Although the embodiments have been described above, the present invention is not limited to the specifically disclosed embodiments above, and various modifications and variations are possible without departing from the scope of the claims.

In addition, all ordinal numbers, quantities, and other numbers used in the description of the embodiments are provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the exemplified numbers. In addition, the connections between the components are provided as examples to specifically explain the technology of the present invention, and the connections that realize the functions of the present invention are not limited to these.

The embodiment also includes a liquid ejection method. For example, the liquid ejection method is a liquid ejection method by a liquid ejection device that ejects and applies liquid onto an ejection receiving medium transported in a predetermined transport direction to form an ejection receiving region, in which a plurality of liquid ejection units eject the liquid based on a drive waveform, output the drive waveform to each of the plurality of liquid ejection units, acquire information indicating the properties of the liquid, and switch the drive waveform based on the properties, and the plurality of liquid ejection units include a first liquid ejection unit and a second liquid ejection unit that is disposed at a position different from the first liquid ejection unit along the transport direction, and when the properties satisfy a predetermined condition, the positions on the ejection receiving medium where the liquid is applied by each of the first liquid ejection unit and the second liquid ejection unit are separated along the transport direction. By such a liquid ejection method, it is possible to obtain the same effect as the above-mentioned liquid ejection device.

Furthermore, each function of the embodiments described above can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, and devices such as an ASIC (Application Specific Integrated Circuit), DSP (digital signal processor), FPGA (field programmable gate array), and conventional circuit modules designed to execute each function described above.

1 Unwinding section 11 Unwinding roll 2 Material to be coated 20 Transport direction 3 Coating section 30, 30a, 30b, 30c, 30d Ink ejection section (an example of a liquid ejection section)
31 Thermistor (an example of a detection unit)
32 Piezoelectric elements 33, 34 Drive waveforms 35a, 35b, 35c, 35d Dot arrays 35a', 35b', 35c', 35d' Dot array after drive waveform switching 4 Curing unit 5 Drying unit 6 Winding unit 61 Winding roll 7 Control unit 71 Acquisition unit 72 Drive waveform storage unit 73 Drive waveform retention unit 74 Output unit 75 Switching unit 76 Amplification unit 9 Inkjet head (an example of an ink ejection head)
10 Nozzle 100 Film forming device (liquid ejection device, liquid ejection device for battery components)
P1a, P2a, P3a Pulse waveform P1b, P2b, P3b Pulse waveform V1, V2 Potential difference

JP 2011-201050 A

Claims (9)

A liquid ejection device that ejects and applies liquid onto an ejection receiving medium transported in a predetermined transport direction to form an ejection receiving region,
a plurality of liquid ejection units capable of ejecting the liquid based on a drive waveform;
an output unit capable of outputting the driving waveform to each of the plurality of liquid ejection units;
An acquisition unit that acquires information indicating a property of the liquid;
A switching unit that switches the drive waveform based on the property,
the plurality of liquid ejection units include a first liquid ejection unit and a second liquid ejection unit disposed at a position different from the first liquid ejection unit along the transport direction,
A liquid ejection device in which, when the properties satisfy specified conditions, the positions at which the liquid is applied by each of the first liquid ejection unit and the second liquid ejection unit on the ejected medium are spaced apart along the transport direction. The liquid ejection device according to claim 1, wherein the switching unit switches between the drive waveforms output to the first liquid ejection unit and the second liquid ejection unit when the property satisfies a predetermined condition. the property being a temperature of the liquid discharged by the liquid discharger,
3. The liquid ejection device according to claim 1, wherein the predetermined condition is satisfied when the temperature of the liquid changes to a predetermined threshold value or more. The liquid ejection device according to any one of claims 1 to 3, wherein each of the plurality of liquid ejection sections includes a plurality of liquid ejection heads arranged in a direction intersecting the transport direction. each of the plurality of liquid ejection units has a detection unit for detecting a temperature of the liquid;
The liquid ejection device according to claim 1 , wherein the property includes the temperature detected by the detection unit. The liquid ejection device according to any one of claims 1 to 5, wherein the first liquid ejection unit and the second liquid ejection unit eject the same type of liquid. The driving waveform includes a pulse waveform,
A liquid ejection device as described in any one of claims 1 to 6, wherein the switching unit switches the first drive waveform to a second drive waveform that is different from the first drive waveform in at least one of the potential, fall timing, pulse width, rise timing, and time interval between multiple pulse waveforms contained in the pulse waveform. A liquid ejection device according to any one of claims 1 to 7,
The liquid ejection device for battery components, wherein the ejection receiving medium is a component contained in a battery. A liquid ejection method using a liquid ejection device, which ejects and applies liquid onto an ejection receiving medium transported in a predetermined transport direction to form an ejection receiving region, comprising:
a step of discharging the liquid from a plurality of liquid dischargers based on a drive waveform;
outputting the driving waveform to each of the plurality of liquid ejection units;
acquiring information indicative of a property of the liquid;
and switching the drive waveform based on the property.
the plurality of liquid ejection units include a first liquid ejection unit and a second liquid ejection unit disposed at a position different from the first liquid ejection unit along the transport direction,
A liquid ejection method, wherein when the properties satisfy predetermined conditions, the positions on the ejection medium at which the liquid is applied by each of the first liquid ejection section and the second liquid ejection section are spaced apart along the transport direction.

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