JP7054880B2 - Printing equipment and printing method - Google Patents

Description

The present invention relates to a printing apparatus and a printing method.

As a method for forming an organic light emitting layer of an organic EL (Electro Luminescence) display panel, there is a method of forming a small molecule organic material or a high molecular weight organic material by a solvent coating method.

As one of the typical means for forming an organic light emitting layer by a solvent coating method, an inkjet printing device is used to eject ink droplets containing an organic light emitting material onto a pixel area of a display substrate to form an organic light emitting layer. There is a way to form. The ink droplets ejected at this time include an organic light emitting material and a solvent.

In a general inkjet printing apparatus, an inkjet head having a plurality of nozzles is used. With the recent increase in resolution and size of displays, the number of nozzles exceeds tens of thousands to 100,000, so the pitch between nozzles is narrowing. Therefore, when a droplet is ejected from each nozzle, the vibration of another nozzle adjacent to the own nozzle (hereinafter referred to as the adjacent nozzle) has an effect on the predetermined ejection nozzle (hereinafter referred to as the own nozzle). The degree of influence (hereinafter referred to as the amount of crosstalk) increases. In addition, in this specification, "adjacent" means that nozzles are adjacent to each other at a predetermined interval.

Further, when the own nozzle is in the ejection state, the amount of crosstalk is generally different between the case where the adjacent nozzle is in the ejection state and the case where the adjacent nozzle is in the non-ejection state. If the amount of crosstalk is different, the ejection speed and the ejection volume of the droplet from the own nozzle will change. For this reason, the landing position and the landing volume of the droplets ejected from the own nozzle differ between the case where the adjacent nozzle is in the ejection state and the case where the adjacent nozzle is in the non-ejection state, and the droplet is the target. It may protrude from the pixel area or the amount of landed droplets may change. As a result, coupling between pixel regions and changes in the film thickness of the light emitting layer occur, and color mixing points, vanishing points, and overlighting points occur in the pixels of the display.

In order to suppress this change in the crosstalk amount, a method of keeping the crosstalk amount constant regardless of the ejection state and the non-ejection state of the adjacent nozzles has been considered (see, for example, Patent Document 1). In this method, when the own nozzle is in the ejection state and the adjacent nozzle is in the non-ejection state, a fine drive pulse that can maintain the non-ejection state is applied to the adjacent nozzle. As a result, it is possible to generate the same amount of crosstalk in the adjacent nozzles in the non-discharged state as in the discharged state. As a result, the amount of crosstalk from the adjacent nozzles of all the nozzles in the ejection state can be kept substantially constant. By keeping the amount of crosstalk constant, it is possible to prevent the landing position and volume of all nozzles from fluctuating.

Further, in order to suppress the change in the amount of crosstalk, there is a method in which the ejection timing of the adjacent nozzle with respect to the own nozzle is slightly changed, the time of the crosstalk received by the own nozzle is shifted, and the fluctuation of the ejection state is reduced. (See, for example, Patent Document 2).

Further, there is a method of canceling the change in the landing position due to the change in the ejection speed by increasing or decreasing the flight speed of the ink by deforming the ejection waveform (see, for example, Patent Document 3).

Here, the method of Patent Document 1 will be described with reference to FIG. The method of Patent Document 1 is a head drive control method that solves the problem that when a nozzle in a ejection state and a nozzle in a non-discharging state are adjacent to each other, the drop velocity decreases due to pressure loss and the landing position shifts.

In FIG. 13, the common drive waveform Vcom is a waveform within one drive cycle. The common drive waveform Vcom includes a fine drive pulse P0 that vibrates the meniscus without ejecting droplets and an ejection pulse P1 that ejects droplets in chronological order. The fine drive pulse P0 is arranged in time series before the discharge pulse P1. The time interval between the fine drive pulse P0 and the discharge pulse P1 is set to a time difference such that the meniscus vibration due to the fine drive pulse P0 propagates to the discharge nozzle due to the discharge pulse P1 and the meniscus vibration and the discharge vibration resonate and vibrate. Has been done.

Further, as shown in FIG. 13, each nozzle 1 to 4 vibrates with the micro-vibration pulse P0 in the case of the non-discharge charge time, and is driven by the discharge pulse P1 in the case of the discharge charge time. As a result, the vibration propagating from the non-discharge nozzle to the discharge nozzle resonates. At the timing T2, the non-discharge fine vibration of the nozzle 1 is added to the discharge vibration of the nozzle 2, and at the timing T3, the non-discharge fine vibration of the nozzle 2 is superimposed on the discharge vibration of the nozzle 1 and the nozzle 3. As a result, the amount of crosstalk between the own nozzle and the other nozzle becomes constant regardless of whether the other nozzle is in the ejection state or the non-ejection state.

Next, the method of Patent Document 3 will be described with reference to FIG. The method of Patent Document 3 is a control method of a liquid injection device capable of suppressing the influence of residual vibration and making the injection characteristics of the liquid uniform.

FIG. 14A shows that the own nozzle is driven by the injection drive pulse DP1 at the timings Tn, Tn + 1, and Tn + 2. The injection drive pulse DP1 is a pulse adjusted to the first injection timing with respect to the LAT signal.

In FIG. 14B, the adjacent nozzles are driven by the injection drive pulse DP1 at the timing Tn, driven by the injection drive pulse DP2 at the timing Tn + 1, and driven by the injection drive pulse DP3 at the timing Tn + 2. It is shown that. The injection drive pulse DP2 is a pulse adjusted to a second injection timing earlier than the first injection timing with respect to the LAT signal. The injection drive pulse DP3 is a pulse adjusted to a third injection timing later than the first injection timing with respect to the LAT signal.

At the timing Tn, the adjacent nozzle is driven by the injection drive pulse DP1 so that the injection drive pulse DP1 of the own nozzle at the timing Tn + 1 does not fall within the “interval between injection instability”.

At the timing Tn + 1, the adjacent nozzles are driven by the injection drive pulse DP2 so that the injection drive pulse DP1 of the own nozzle at the timing Tn + 2 does not fall within the “interval between injection instability”.

Similarly to the above, after the timing Tn + 2, the injection drive pulse of the other nozzle is selected so that the injection drive pulse of the own nozzle does not fall within the “instantaneous injection interval”.

As a result, the own nozzle and the adjacent nozzle can use the injection drive pulse in which the injection is stable, and the crosstalk between the nozzles can be reduced.

Further, the injection drive pulse DP2 has a smaller pulse wave height difference than the injection drive pulse DP1. As a result, the injection speed of the ink can be slowed down, and the movement of the landing position due to the injection at a time earlier than that of the injection drive pulse DP1 can be offset. On the other hand, the injection drive pulse DP3 has a larger pulse wave height difference than the injection drive pulse DP1. As a result, the injection speed of the ink can be increased, and the movement of the landing position due to the injection at a time later than that of the injection drive pulse DP1 can be offset.

Japanese Unexamined Patent Publication No. 2016-010941 Japanese Unexamined Patent Publication No. 2005-238728 JP-A-2015-139915

However, the methods of Patent Documents 1 to 3 have a problem that the absolute amount of crosstalk cannot be suppressed to a very small amount.

For example, in order to realize high resolution of the display panel, it is required to reduce the volume amount of each nozzle and the distance between the nozzles (nozzle pitch) for the same coating area. That is, in each nozzle, it is necessary to reduce the discharge amount, shorten the distance between the nozzles, and increase the number of discharges.

In order to reduce the discharge amount and the nozzle pitch, it is necessary to reduce the size of the nozzle chamber, and the vibration generation amount of the own nozzle generated between the nozzle chambers and the vibration reception amount from other nozzles are remarkably increased. Therefore, it is necessary to reduce the absolute amount of crosstalk.

An object of the present invention is to provide a printing device and a printing method capable of remarkably suppressing the amount of crosstalk between the own nozzle and the adjacent nozzle regardless of the ejection state and the non-ejection state of the adjacent nozzles.

The printing device according to one aspect of the present invention is a printing device that prints an image on an object by using a plurality of nozzles arranged in a row and whose ejection of droplets is controlled based on a predetermined waveform. Of the plurality of nozzles, based on the information of the generation unit that generates the reference discharge waveform or the delayed discharge waveform having a predetermined delay amount with respect to the reference discharge waveform, and the image read from the predetermined storage unit. The control unit includes a control unit that assigns the reference discharge waveform or the delayed discharge waveform to the discharge nozzle that discharges the droplets, and the control unit includes two or more adjacent discharge nozzles. Of the group, the reference discharge waveform is assigned to the 2nth (n is an odd number) nozzle and the 2n + 1st nozzle, and the delayed discharge is assigned to the 2mth (m is an even number) nozzle and the 2m + 1st nozzle. A waveform is assigned, and the generating unit generates a reference non-ejection tickle waveform that generates a tickle vibration that is in phase with the reference ejection waveform and has a direction of displacement opposite to that of the reference ejection waveform. , The reference non-discharge tickle waveform is assigned to the first non-discharge nozzle which is adjacent to one end of the discharge nozzle group and does not discharge droplets .

The printing method according to one aspect of the present invention is a printing method for printing an image on an object by using a plurality of nozzles arranged in a row and controlling the ejection of droplets based on a predetermined waveform. Based on the first step of generating the reference discharge waveform or the delayed discharge waveform having a predetermined delay amount with respect to the reference discharge waveform, and the information of the image read from the predetermined storage unit, the plurality of nozzles Among them, a second step of assigning the reference discharge waveform or the delayed discharge waveform to the discharge nozzle for discharging the droplet is provided, and in the second step, two or more adjacent discharge nozzles are used. Among the included discharge nozzle groups, the reference discharge waveform is assigned to the 2nth (n is an odd) nozzle and the 2n + 1st nozzle, and the 2mth (m is an even) nozzle and the 2m + 1st nozzle are assigned. A third step of assigning the delayed discharge waveform and further generating a reference non-discharge tickle waveform that generates a tickle vibration that is in phase with the reference discharge waveform and has a direction of displacement opposite to that of the reference discharge waveform, and the discharge. Includes a fourth step of assigning the reference non-ejection tickle waveform to a first non-ejection nozzle that is adjacent to one end of the nozzle group and does not eject droplets .

According to the present invention, the amount of crosstalk between the own nozzle and the adjacent nozzle can be remarkably suppressed regardless of the ejection state or the non-ejection state of the adjacent nozzle.

Cross-sectional view showing a configuration example of a general inkjet head Explanatory drawing showing the drive waveform applied to the piezo element and the displacement amount of the meniscus generated when the drive waveform is applied. FIG. 2 is a diagram showing fluctuations in discharge speed when the pulse width T1 of the drive waveform of FIG. 2A is changed. Explanatory drawing when the drive timing of two adjacent nozzles is staggered The figure which shows the fluctuation of the ejection speed of one nozzle when the drive timing of two adjacent nozzles is shifted. The figure which shows the structural example of the inkjet printing apparatus which concerns on Embodiment 1 of this invention. The figure which shows the relationship between the pixel classification and the waveform classification which concerns on Embodiment 1 of this invention. The figure which shows the state of the interference of the vibration wave between the nozzles in the case of two-nozzle discharge which concerns on Embodiment 1 of this invention. The figure which shows the state of the interference of the vibration wave between the nozzles in the case of 3 nozzle discharge which concerns on Embodiment 1 of this invention. The figure which shows the state of the interference of the vibration wave between the nozzles in the case of 4 nozzle discharge which concerns on Embodiment 1 of this invention. The figure which shows the state of the interference of the vibration wave between the nozzles in the case of 5 nozzle ejection which concerns on Embodiment 1 of this invention. Sectional drawing which shows the structural example of the inkjet head which concerns on Embodiment 2 of this invention. The figure which shows the fluctuation of the ejection speed when the pulse width T1 of the drive waveform is changed in Embodiment 2 of this invention. The figure which shows the fluctuation of the ejection speed of one nozzle at the time of shifting the drive timing of two adjacent nozzles in Embodiment 2 of this invention. Sectional drawing which shows the structural example of the inkjet head which concerns on Embodiment 3 of this invention. The figure which shows the fluctuation of the ejection speed when the pulse width T1 of the drive waveform is changed in Embodiment 3 of this invention. The figure which shows the fluctuation of the ejection speed of one nozzle at the time of shifting the drive timing of two adjacent nozzles in Embodiment 3 of this invention. Sectional drawing which shows the structural example of the inkjet head which concerns on Embodiment 4 of this invention. The figure which shows the fluctuation of the ejection speed when the pulse width T1 of the drive waveform is changed in Embodiment 4 of this invention. The figure which shows the fluctuation of the ejection speed of one nozzle at the time of shifting the drive timing of two adjacent nozzles in Embodiment 4 of this invention. Explanatory drawing of the method of keeping a constant amount of crosstalk disclosed in Patent Document 1. Explanatory drawing of method for avoiding crosstalk influence time disclosed in Patent Document 2

(Vibration mechanism)
First, the mechanism of vibration generated when ink droplets are ejected from a nozzle will be described.

FIG. 1 is a cross-sectional view schematically showing the configuration of a general inkjet head 20. Hereinafter, the inkjet head 20 for ejecting ink droplets (hereinafter referred to as ink droplets) will be described as an example, but the liquid used for ejection is not limited to ink in carrying out the present invention.

The inkjet head 20 has a nozzle 12 which is an ink droplet ejection port, an ink chamber 14 communicating with the nozzle 12, and an actuator 30 provided corresponding to the ink chamber 14. The arrows in FIG. 1 indicate the flow of ink.

The ink flows into the inkjet head 20 from the supply port 40, and flows into the ink chamber 14 through the throttle flow path 15 on the upstream side (right side in the drawing). After that, the ink passes through the throttle flow path 15 on the downstream side (left side in the drawing) and is discharged from the ejection port 41 to the outside of the inkjet head 20. The supply port 40 and the discharge port 41 communicate with another ink chamber (not shown).

The nozzle 12 is a through hole for ejecting ink droplets, and its diameter is about 5 to 40 μm. Examples of the method for processing the through hole include a method such as laser processing, etching, or punching.

The ink chamber 14 has a function of appropriately storing the pressure generated by the vibration of the actuator 30. The ink chamber 14 is manufactured by heat diffusion bonding of a metal plate processed by etching or the like, or etching of a silicon material or the like.

For example, the drive waveform W shown in FIG. 2A is applied to the piezo element constituting the actuator 30. As a result, the piezo element is deformed, the volume of the ink chamber 14 changes, and ink droplets are ejected from the nozzle 12. In the upper part of FIG. 2A (the portion where the drive waveform W is shown), the horizontal axis shows the time after the drive waveform W is applied, and the vertical axis shows the voltage to be applied.

At this time, the meniscus of the ink formed on the nozzle 12 becomes the vibration V shown in FIG. 2A. In the lower part of FIG. 2A (the portion where the vibration V is shown), the horizontal axis shows the time after the drive waveform W is applied, and the vertical axis shows the displacement amount of the meniscus.

FIG. 2B shows the results of measuring the ejection speed of the ink droplets when the time of the pulse width T1 of the drive waveform W shown in FIG. 2A is changed. In FIG. 2B, the horizontal axis represents the time of the pulse width T1 shown in FIG. 2A, and the vertical axis represents the ejection speed of the ink droplet.

From FIG. 2B, it can be seen that the discharge speed changes depending on the time of the pulse width T1. When the pulse width T1 of the drive waveform is set with a period 1/2 times that of the natural vibration cycle Tr of the meniscus, the vibration wave of the meniscus resonates and the speed becomes faster. In the example of FIG. 2B, when the pulse width T1 is 2.8 microseconds, the ejection speed is the fastest, and the resonance period Tr in the inkjet head 20 is 5.6 microseconds.

Here, the evaluation of the ejection speed when a plurality of nozzles 12 are driven by using the inkjet head 20 will be described with reference to FIGS. 3A and 3B.

For example, as shown in FIG. 3A, it is assumed that the nozzle a and the nozzle b adjacent thereto are driven by shifting the timing Ts. The fluctuation of the ejection speed of the nozzle b at this time is shown in FIG. 3B. From FIG. 3B, it can be seen that the discharge speed is the fastest when the timing Ts is 4.2 microseconds. The resonance period Tr is 5.6 microseconds.

This is because, in addition to the vibration of the meniscus of the nozzle b itself, the vibration driven by the nozzle a propagates to the nozzle b, and the vibration waves interfere with each other and cross-talk, so that the speed of the nozzle b fluctuates. It is thought that this is the reason.

The vibration wave of the adjacent nozzle propagates with a time difference of 4.2 microseconds, which is 0.75 times the time of the vibration wave with resonance period Tr = 5.6 microseconds, and mutual interference of the vibration waves occurs. There is.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The components common to each figure are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

(Embodiment 1)
The inkjet head printing apparatus according to the first embodiment of the present invention (an example of the printing apparatus of the present invention) aims to suppress mutual interference of the above-mentioned vibration waves.

<Device configuration>
The configuration of the inkjet printing apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a configuration example of the inkjet printing apparatus of the present embodiment.

The substrate 1 is an object on which an image is printed due to the impact of ink droplets. Examples of the material of the substrate 1 include plastic and glass. The ink may land on the substrate 1 to form, for example, a functional film of an organic EL.

It is assumed that there are a plurality of pixel cells 2 (nine in the example of the figure) on the substrate 1, and each pixel cell 2 is satisfied with the required amount of ink by ejecting three drops. The black circles in the figure are the discharge positions, and the white circles in the figure are the non-discharge positions.

The coating image 3 is information (hereinafter, also referred to as discharge / non-discharge information) that two-dimensionally indicates the discharge position or the non-discharge position on the substrate 1. The ejection position is a position (pixel) on the substrate 1 on which ink droplets are ejected (that is, printing). The non-ejection position is a position (pixel) on the substrate 1 where ink droplets are not ejected.

The discharge position and the non-discharge position are two-dimensional coordinate positions including the nozzle arrangement direction and the stage scan (SCAN) direction of the substrate 1, and are the intersections of the broken lines in the figure.

Further, the rectangular circle in the figure is the pixel cell 2 described above. In the pixel cell 2, three drops of ink are ejected in a straight line along the nozzle arrangement direction.

Further, in the coated image 3, the black circles are the ejection pixels 4a, the black triangles are the delayed ejection pixels 4b, the white circles are the non-ejection pixels 4c, and the white triangles are the delayed non-ejection pixels 4d. These differences will be described later.

The print data holding memory 5 (an example of the storage unit) holds the coated image 3.

The moving stage 6 mounts the substrate 1 and moves the substrate 1.

The position detector 7 detects the moving position of the moving stage 6, and outputs information indicating the position (hereinafter, referred to as stage position information) to the discharge timing generator 8.

The ejection timing generator 8 generates a timing signal for ejecting ink based on the position indicated by the stage position information, and outputs the timing signal to the drive waveform signal generator 9.

The drive waveform signal generator 9 (an example of a generator) has a drive waveform (for example, a reference discharge waveform 9a, a delayed discharge waveform 9b, a reference non-discharge tickle waveform 9c, etc.) based on the timing signal received from the discharge timing generator 8. Alternatively, a signal with a delayed non-discharge tickle waveform 9d) is generated. The difference between these waveforms will be described later with reference to FIG.

The nozzle drive controller 10 (an example of the control unit) reads the ejection / non-ejection information (coating image 3) from the print data holding memory 5, and based on the information, outputs the driving waveform received from the driving waveform signal generator 9. Output to each nozzle a to l of the inkjet head 11.

The inkjet head 11 has a plurality of nozzles a to l for ejecting ink droplets. The inkjet head 11 ejects ink droplets based on the drive waveform received from the nozzle drive controller 10 for each nozzle a to l. The internal configuration of the inkjet head 11 is the same as the configuration of the inkjet head 20 shown in FIG.

Next, using FIG. 5, the pixel classification (discharge pixel 4a, delayed discharge pixel 4b, non-discharge pixel 4c, delayed non-discharge pixel 4d) and waveform classification (reference discharge waveform 9a, delayed discharge waveform 9b) of the coated image 3 are used. The relationship with the reference non-discharge tickle waveform 9c or the delayed non-discharge tickle waveform 9d) will be described.

The reference discharge waveform 9a and the delayed discharge waveform 9b shown in FIG. 5 are waveforms for discharge. The delayed discharge waveform 9b is a waveform delayed by a certain time (Td) with respect to the reference discharge waveform 9a. This constant time (Td) is set based on the resonance period. The details will be described later.

The reference non-ejection tickle waveform 9c and the delayed non-ejection tickle waveform 9d shown in FIG. 5 are non-ejection waveforms, and are tickle waveforms that swing the ink in the nozzle chamber (see FIG. 1). The delayed non-discharge tickle waveform 9d is a tickle waveform delayed by a certain time (Td) with respect to the reference non-discharge tickle waveform 9c.

The voltage in the tickle waveform varies depending on the type of ink and cannot be unconditionally determined, but it is a small voltage so that the ink in the ink chamber does not pop out from the nozzle. The pulse width of the tickle waveform is set to be equal to the pulse width of the discharge waveform.

The nozzle drive controller 10 outputs one of the drive waveforms shown in FIG. 5 for each nozzle a to l based on the ejection / non-ejection information (coating image 3) read from the print data holding memory 5. Specifically, the nozzle drive controller 10 outputs the reference ejection waveform 9a to the ejection pixel 4a and outputs the delayed ejection waveform 9b to the delayed ejection pixel 4b. Further, the nozzle drive controller 10 outputs a reference non-ejection tickle waveform 9c to the non-ejection pixel 4c and outputs a delayed non-ejection tickle waveform 9d to the delayed non-ejection pixel 4d.

<Process>
Hereinafter, each example of the operation of neutralizing the crosstalk from the adjacent nozzles (hereinafter referred to as the crosstalk neutralization operation), which is a feature of the present embodiment, will be described with reference to FIGS. 6 to 9.

First, the crosstalk neutralization operation when ink droplets are simultaneously ejected from two nozzles (hereinafter referred to as two nozzle ejection) will be described with reference to FIG. FIG. 6 is a diagram showing a state of interference of vibration waves between nozzles in the case of ejection of two nozzles.

In FIG. 6, the sine and cosine waveform schematically represents the vibration of the meniscus of the ink in each nozzle (the same applies to FIGS. 7 to 9). Actually, the vibration is attenuated with the passage of time, but for the sake of simplicity, the attenuation is omitted (the same applies to FIGS. 7 to 9).

Further, in FIG. 6, the vibration wave A shown by the solid line is a vibration waveform driven by the own nozzle. The vibration wave B shown by the dotted line is a vibration waveform driven by one adjacent nozzle (nozzle adjacent to the left side in the figure in FIG. 1). The vibration wave C shown by the alternate long and short dash line is a vibration waveform driven by the other adjacent nozzle (the nozzle adjacent to the right side in the figure in FIG. 1). The same applies to FIGS. 7 to 9 for these vibration waves A to C.

For example, among the nozzles a to d shown in FIG. 4, it is assumed that ink droplets are simultaneously ejected from the nozzle b and the nozzle c. In this case, the nozzle drive controller 10 performs the following crosstalk neutralization operation. That is, the nozzle drive controller 10 applies the reference ejection waveform 9a to the nozzle b and the nozzle c (may be referred to as “output”), and applies the reference non-ejection tickle waveform 9c to the nozzle a and the nozzle d. In addition, none of the waveforms shown in FIG. 5 is applied to the nozzles e to l.

As a result, for example, in the nozzle b, a vibration wave A driven by the nozzle b itself is generated, and the vibration wave B driven by the adjacent nozzle a and the vibration wave C driven by the adjacent nozzle c are delayed by a certain period of time. Is transmitted. Here, since the directions of vibration are opposite between the nozzle a and the nozzle c, the directions of displacement of the transmitted vibration wave are also opposite. Therefore, the vibration wave B and the vibration wave C transmitted to the nozzle b cancel each other out.

Therefore, the vibration wave of the nozzle b (an example of its own nozzle) itself does not interfere with the vibration wave transmitted from the nozzles a and c (an example of an adjacent nozzle), and normal ink droplet ejection can be realized.

Further, also in the nozzle c, the vibration wave B and the vibration wave C are canceled out in the same manner as in the nozzle b. Therefore, the vibration wave of the nozzle c (an example of its own nozzle) itself does not interfere with the vibration wave transmitted from the nozzles b and d (an example of an adjacent nozzle), and normal ink droplet ejection can be realized.

Next, with reference to FIG. 7, a crosstalk neutralization operation when ink droplets are simultaneously ejected from three nozzles (hereinafter referred to as three nozzle ejection) will be described. FIG. 7 is a diagram showing a state of interference of vibration waves between nozzles in the case of ejection from three nozzles.

For example, it is assumed that ink droplets are simultaneously ejected from the nozzles b, c, and d among the nozzles a to d shown in FIG. In this case, the nozzle drive controller 10 performs the following crosstalk neutralization operation. That is, the nozzle drive controller 10 applies the reference discharge waveform 9a to the nozzle b and the nozzle c, applies the delayed discharge waveform 9b to the nozzle d, and applies the reference non-discharge tickle waveform 9c to the nozzle a and the nozzle e. In addition, none of the waveforms shown in FIG. 5 is applied to the nozzles f to l.

As a result, the vibration wave B and the vibration wave C cancel each other out in the nozzles b to d. Therefore, the vibration wave of the own nozzle does not interfere with the vibration wave transmitted from the adjacent nozzle, and normal ink droplet ejection can be realized.

Next, with reference to FIG. 8, a crosstalk neutralization operation in the case where ink droplets are simultaneously ejected from four nozzles (hereinafter referred to as four nozzle ejection) will be described. FIG. 8 is a diagram showing a state of interference of vibration waves between nozzles in the case of 4-nozzle ejection.

For example, among the nozzles a to d shown in FIG. 4, it is assumed that ink droplets are simultaneously ejected from the nozzles b, c, d, and e. In this case, the nozzle drive controller 10 performs the following crosstalk neutralization operation.

That is, the nozzle drive controller 10 applies the reference discharge waveform 9a to the nozzle b and the nozzle c, and applies the delayed discharge waveform 9b to the nozzle d and the nozzle e. Further, the nozzle drive controller 10 applies the reference non-discharge tickle waveform 9c to the nozzle a and applies the delayed non-discharge waveform 9d to the nozzle f. In addition, none of the waveforms shown in FIG. 5 is applied to the nozzles g to l.

As a result, the vibration wave B and the vibration wave C cancel each other out in the nozzles b to e. Therefore, the vibration wave of the own nozzle does not interfere with the vibration wave transmitted from the adjacent nozzle, and normal ink droplet ejection can be realized.

Next, with reference to FIG. 9, a crosstalk neutralization operation in the case where ink droplets are simultaneously ejected from five nozzles (hereinafter referred to as five nozzle ejection) will be described. FIG. 9 is a diagram showing a state of interference of vibration waves between nozzles in the case of 5-nozzle ejection.

For example, among the nozzles a to d shown in FIG. 4, it is assumed that ink droplets are simultaneously ejected from the nozzles b, c, d, e, and f. In this case, the nozzle drive controller 10 performs the following crosstalk neutralization operation.

That is, the nozzle drive controller 10 applies the reference discharge waveform 9a to the nozzle b, the nozzle c, and the nozzle f, and applies the delayed discharge waveform 9b to the nozzle d and the nozzle e. Further, the nozzle drive controller 10 applies the reference non-discharge tickle waveform 9c to the nozzle a and applies the delayed non-discharge waveform 9d to the nozzle g. In addition, none of the waveforms shown in FIG. 5 is applied to the nozzles h to l.

As a result, the vibration wave B and the vibration wave C cancel each other out in the nozzles b to f. Therefore, the vibration wave of the own nozzle does not interfere with the vibration wave transmitted from the adjacent nozzle, and normal ink droplet ejection can be realized.

Although each crosstalk neutralization operation in 2 to 5 nozzle ejections has been described above, the crosstalk neutralization operation can be performed even when ink is ejected from 6 or more nozzles at the same time. That is, the crosstalk neutralization operation of this embodiment can be summarized as follows.

In the following description, the nozzles that eject ink droplets are collectively referred to as "ejection nozzle group". The ejection nozzle group includes two or more adjacent nozzles. Further, a nozzle adjacent to one end (for example, the left side) of the ejection nozzle group and not ejecting ink droplets is referred to as a "first non-ejection nozzle". Further, a nozzle that is adjacent to the other end (for example, the right side) of the ejection nozzle group and does not eject ink droplets is referred to as a "second non-ejection nozzle". For example, in FIG. 4, when the discharge nozzle group is nozzles b and c, the first non-discharge nozzle is nozzle a and the second non-discharge nozzle is nozzle d.

For example, the first non-discharge nozzle is a dummy nozzle. Then, a reference non-discharge tickle waveform 9c is assigned to the first non-discharge nozzle.

Further, in the discharge nozzle group, the reference discharge waveform 9a is assigned to the 2nth nozzle and the 2n + 1st nozzle (n is an odd number). On the other hand, in the discharge nozzle group, the delayed discharge waveform 9b is assigned to the 2mth nozzle and the 2m + 1st nozzle (m is an even number). In this way, either the reference discharge waveform 9a or the delayed discharge waveform 9b is assigned to each nozzle of the discharge nozzle group.

Either the reference non-discharge tickle waveform 9c or the delayed non-discharge tickle waveform 9d is assigned to the second non-discharge nozzle. For example, when the reference discharge waveform 9a is assigned to the nozzle located second from the second non-discharge nozzle group in the discharge nozzle group, the reference non-discharge tickle waveform 9c is assigned to the second non-discharge nozzle. On the other hand, for example, when the delayed discharge waveform 9b is assigned to the nozzle located second from the second non-discharge nozzle group in the discharge nozzle group, the delayed non-discharge tickle waveform 9d is assigned to the second non-discharge nozzle. ..

As described above, even if the number of nozzles is increased, the crosstalk neutralization operation of the present embodiment can be applied.

<Example of crosstalk neutralization operation>
The case where the above-mentioned crosstalk neutralization operation is performed by the inkjet head printing apparatus shown in FIG. 4 will be described.

Here, a substrate having 10 pixels in the nozzle arrangement direction (horizontal direction in FIG. 4) x 9 pixels in the stage scan direction (vertical direction in FIG. 4) using an inkjet head 11 provided with 12 nozzles a to l. The case of printing on the upper grid will be described as an example. Further, here, it is assumed that nine pixel cells 2 are arranged on the substrate 1 and three drops of ink are landed on each pixel cell 2.

First, using three pixel cells 2 and 12 pixels including 10 pixels in the nozzle arrangement direction and 2 pixels on both sides of those 10 pixels, ink droplets are ejected to the three pixel cells 2 in the nozzle arrangement direction. Decide which nozzle to use.

After that, the non-ejection pixel for the nozzle a, the ejection pixel or the non-ejection pixel for the nozzles b and c, the delayed ejection pixel or the delayed non-ejection pixel for the nozzles d and e, and so on. Make an assignment. The delayed ejection pixel or the delayed non-discharging pixel is a pixel in which the time Td (time 0.75 times the resonance period Tr) is shifted. Non-ejection pixels are assigned to the nozzle l.

For example, when the scan position is on the pixel cell 2, the non-ejection pixels 4c (white circles shown in FIG. 4) are assigned to the nozzles a, e, and l, and the reference non-ejection tickle waveform 9c is assigned. Further, the ejection pixels 4a (black circles shown in FIG. 4) are assigned to the nozzles b, c, f, g, j, and k, and the reference ejection waveform 9a is assigned. Further, the delayed ejection pixels 4b (black triangles shown in FIG. 4) are assigned to the nozzles d, h, and i, and the delayed ejection waveform 9b is assigned.

Further, for example, in a substrate grid whose scan position is other than the pixel cell 2, delayed non-ejection pixels 4d (white triangles shown in FIG. 4) are assigned to nozzles d, h, and i, and a delayed non-ejection tickle waveform is used. 9d is assigned. Further, the non-ejection pixels 4c (white circles shown in FIG. 4) are assigned to the nozzles a, b, c, e, f, g, j, and k, and the reference non-ejection tickle waveform 9c is assigned.

The drive waveform signal generator 9 is prepared to generate the reference discharge waveform 9a, the delayed discharge waveform 9b, the reference non-discharge tickle waveform 9c, and the delayed non-discharge tickle waveform 9d shown in FIG.

When the substrate 1 is mounted on the moving stage 6 and the moving stage 6 is moved, a four-phase position signal of a sine wave or a pulse wave is output from the moving stage 6 to the position detector 7. The position detector 7 converts the four-phase signal into a fine position signal and then outputs the signal to the discharge timing generator 8.

The discharge timing generator 8 generates a discharge timing signal based on the position signal so that the coating image 3 is completely printed on the substrate 1. Then, the discharge timing generator 8 outputs the discharge timing signal to the drive waveform signal generator 9 and the print data holding memory 5.

Based on the discharge timing signal, the drive waveform signal generator 9 has a reference discharge waveform 9a, a delayed discharge waveform 9b, a reference non-discharge tickle waveform 9c, and a delayed non-discharge tickle waveform 9d (collectively referred to as waveforms below). 9a-9d) is output to the nozzle drive controller 10.

The print data holding memory 5 outputs the pixel data of the nozzles a to l to the nozzle drive controller 10 for each ejection timing based on the ejection timing signal. The pixel data is, for example, data of four types of pixels 4a to 4d (see FIG. 5) corresponding to the coating image 3 in the print data holding memory 5.

The nozzle drive controller 10 selects one of the four types of waveforms 9a to 9d received from the drive waveform signal generator 9 based on the four types of pixel data from the print data holding memory 5. This selection is made for each nozzle a to l. Then, the nozzle drive controller 10 outputs any of the selected waveforms 9a to 9d to the inkjet head 11 for each nozzle a to l.

The inkjet head 11 ejects ink droplets or prevents ink droplets from being ejected for each nozzle a to l based on the waveforms 9a to 9d.

When the above operation is performed for the scan pixels of the coated image 3, the coated image 3 is printed on the substrate 1.

Further, there is a discrepancy between the landing position of the ink ejected based on the delayed ejection waveform 9b on the substrate 1 and the landing position of the ink ejected based on the reference ejection waveform 9a on the substrate 1. This is because the moving stage 6 moves the substrate 1.

Therefore, in order to correct the deviation, for example, the nozzle drive controller 10 calculates the discharge speed difference based on the moving speed of the substrate 1 or the inkjet head 11 and the distance between the inkjet head 11 and the substrate 1, and this The delayed discharge waveform 9b may be deformed so that the discharge speed is increased by the discharge speed difference, and the deformed delayed discharge waveform 9b may be output to a predetermined nozzle (for example, the nozzle d when three nozzles are simultaneously discharged). As a method of deforming the delayed discharge waveform 9b, for example, there are a method of increasing the rising angle (slew rate) of the rectangular portion of the waveform, a method of increasing the peak value potential of the rectangle, and the like.

In the example of FIG. 4, the nozzles a to l of the inkjet head 11 are arranged perpendicular to the substrate 1, but in order to narrow the pitch between the nozzles, the nozzles a to l are arranged diagonally. May be good.

<Effect>
According to the crosstalk neutralization operation described above, a reference waveform and a delay waveform are prepared, and they are repeatedly assigned to every two nozzles, and non-ejection waveforms are assigned to the nozzles at both ends of the entire nozzle row, so that between adjacent nozzles. It is possible to neutralize all the crosstalk in.

Therefore, in the present embodiment, the amount of crosstalk between the own nozzle and the adjacent nozzle can be remarkably suppressed regardless of the ejection state and the non-ejection state of the adjacent nozzles. As a result, for example, the landing position of the ink droplets and the volume amount of the ink droplets are stable, the film thickness of the light emitting layer can be made uniform without protruding from the pixel region, and the pixel has a high resolution with no blind spots, color mixing points, and uneven brightness. Electronic devices with high quality displays can be manufactured.

(Embodiment 2)
If the structure of the ink head head is different, the resonance period Tr is different, and the timing Ts for crosstalk between adjacent nozzles is also different. In the present embodiment, a case where an inkjet head 11a having a structure different from that of the inkjet head 11 (see FIG. 1) of the first embodiment will be used will be described with reference to FIGS. 10A to 10C.

FIG. 10A is a cross-sectional view showing a configuration example of the inkjet head 11a according to the present embodiment. FIG. 10B is a diagram showing fluctuations in the ejection speed of the inkjet head 11a when the pulse width T1 (see FIG. 2A) of the drive waveform is changed. FIG. 10C is a diagram showing fluctuations in the ejection speed of the nozzle b when the nozzle a of the inkjet head 11a and the nozzle b adjacent thereto are driven by shifting the timing Ts (see FIG. 3A).

As shown in FIG. 10A, the inkjet head 11a is different from the inkjet head 11 shown in FIG. 1 in that it includes a throttle flow path 16. The inkjet head printing apparatus shown in FIG. 4 includes an inkjet head 11a instead of the inkjet head 11.

When the pulse width T1 (see FIG. 2A) of the drive waveform is changed in the inkjet head 11a, the ejection speed becomes the fastest when the timing T1 is 3.3 microseconds as shown in FIG. 10B. The resonance period Tr is 6.6 microseconds.

Then, it is assumed that the nozzle a of the inkjet head 11a and the nozzle b adjacent to the nozzle a are driven by shifting the timing Ts. As shown in FIG. 10C, the ejection speed of the nozzle b at this time becomes the fastest when the timing Ts is 6.0 microseconds. At this timing Ts, the crosstalk from the adjacent nozzles becomes maximum.

Therefore, in the present embodiment, for example, the nozzle drive controller 10 sets the delay amount of the delayed waveform (delayed discharge waveform 9b, delayed non-discharge tickle waveform 9d) based on the ratio R before the start of printing. The ratio R is a ratio (Ts / Tr) between the resonance period Tr and the timing (arrival time of the vibration wave propagating from the adjacent nozzle) Ts.

For example, as described above, when the timing Ts is 6.0 microseconds and the resonance period Tr is 6.6 microseconds, the ratio R is about 0.91. The nozzle drive controller 10 is set to delay the delay waveform for a time 0.91 times the resonance period Tr of the reference waveform (reference discharge waveform 9a, reference non-ejection tickle waveform 9c).

(Embodiment 3)
In the present embodiment, a case where an inkjet head 11b having a structure different from that of the inkjet head 11 (see FIG. 1) of the first embodiment will be used will be described with reference to FIGS. 11A to 11C.

FIG. 11A is a cross-sectional view showing a configuration example of the inkjet head 11b according to the present embodiment. FIG. 11B is a diagram showing fluctuations in the ejection speed of the inkjet head 11b when the pulse width T1 (see FIG. 2A) of the drive waveform is changed. FIG. 11C is a diagram showing fluctuations in the ejection speed of the nozzle b when the nozzle a of the inkjet head 11b and the nozzle b adjacent thereto are driven by shifting the timing Ts (see FIG. 3A).

As shown in FIG. 11A, the inkjet head 11b is different from the inkjet head 11 shown in FIG. 1 in that it includes a throttle flow path 17 longer than the throttle flow path 15. The length of the throttle flow path 17 is about four times the length of the throttle flow path 15. The inkjet head printing apparatus shown in FIG. 4 includes an inkjet head 11b instead of the inkjet head 11.

When the pulse width T1 (see FIG. 2A) of the drive waveform is changed in the inkjet head 11b, the ejection speed becomes the fastest when the timing T1 is 3.7 microseconds as shown in FIG. 11B. The resonance period Tr is 7.4 microseconds.

Then, it is assumed that the nozzle a of the inkjet head 11b and the nozzle b adjacent to the nozzle a are driven by shifting the timing Ts. As shown in FIG. 11C, the ejection speed of the nozzle b at this time becomes the fastest when the timing Ts is 7.0 microseconds. At this timing Ts, the crosstalk from the adjacent nozzles becomes maximum.

Therefore, in the present embodiment, as in the second embodiment, for example, the nozzle drive controller 10 sets the delay amount of the delay waveform based on the ratio R before the start of printing. For example, as described above, when the timing Ts is 7.0 microseconds and the resonance period Tr is 7.4 microseconds, the ratio R is about 0.95. The nozzle drive controller 10 sets the delay waveform to be delayed for 0.95 times the resonance period Tr of the reference waveform.

(Embodiment 4)
In the present embodiment, a case where the inkjet head 11c having a structure different from that of the inkjet head 11 of the first embodiment (see FIG. 1) is used will be described with reference to FIGS. 12A to 12C.

FIG. 12A is a cross-sectional view showing a configuration example of the inkjet head 11c according to the present embodiment. FIG. 12B is a diagram showing fluctuations in the ejection speed of the inkjet head 11b when the pulse width T1 (see FIG. 2A) of the drive waveform is changed. FIG. 12C is a diagram showing fluctuations in the ejection speed of the nozzle b when the nozzle a of the inkjet head 11c and the nozzle b adjacent thereto are driven by shifting the timing Ts (see FIG. 3A).

As shown in FIG. 12A, the inkjet head 11c is different from the inkjet head 11 shown in FIG. 1 in that it includes an ink chamber 18 having a volume smaller than that of the ink chamber 14. The volume of the ink chamber 18 is about 1/4 of the volume of the ink chamber 14. The inkjet head printing apparatus shown in FIG. 4 includes an inkjet head 11c instead of the inkjet head 11.

When the pulse width T1 (see FIG. 2A) of the drive waveform is changed in the inkjet head 11c, the ejection speed becomes the fastest when the timing T1 is 1.8 microseconds as shown in FIG. 12B. The resonance period Tr is 3.6 microseconds.

Then, it is assumed that the nozzle a of the inkjet head 11c and the nozzle b adjacent to the nozzle a are driven by shifting the timing Ts. As shown in FIG. 12C, the ejection speed of the nozzle b at this time becomes the fastest when the timing Ts is 4.0 microseconds. At this timing Ts, the crosstalk from the adjacent nozzles becomes maximum.

Therefore, in the present embodiment, as in the second embodiment, for example, the nozzle drive controller 10 sets the delay amount of the delay waveform based on the ratio R before the start of printing. For example, as described above, when the timing Ts is 4.0 microseconds and the resonance period Tr is 3.6 microseconds, the ratio R is about 1.1. The nozzle drive controller 10 sets the delay waveform to be delayed for 1.1 times the resonance period Tr of the reference waveform.

As described above, according to the second to fourth embodiments, the crosstalk between the own nozzle and the adjacent nozzles is not limited to the ejection state and the non-ejection state of the adjacent nozzles, as in the first embodiment. The amount can be significantly suppressed. As a result, for example, the landing position of the ink droplets and the volume amount of the ink droplets are stable, the film thickness of the light emitting layer can be made uniform without protruding from the pixel region, and the pixel has a high resolution with no blind spots, color mixing points, and uneven brightness. Electronic devices with high quality displays can be manufactured.

The present invention is not limited to the above description of the first to fourth embodiments, and various modifications can be made without departing from the spirit of the present invention. Hereinafter, a modified example will be described.

[Modification 1]
In the first to fourth embodiments, the delay amounts of the delayed ejection waveform 9b and the delayed non-ejection waveform 9c are 0.5 to 1.5 times (preferably 0.75 times to 1.) the resonance period of the meniscus of the ink. It may be in the range of 1 times).

[Modification 2]
In the first to fourth embodiments, the reference non-discharge waveform 9c and the delayed non-discharge waveform 9d may not be used. In that case, the ejection pixels and the non-ejection pixels in which ink droplets are ejected at the same time at the time of scanning are assigned to a series of nozzles. For example, the reference discharge waveform 9a is assigned to the 2nth nozzle and the 2n + 1st nozzle (n is an odd number). Further, the delayed discharge waveform 9b is assigned to the 2mth nozzle and the 2m + 1st nozzle (m is an even number). The first nozzle and the final nozzle are the same as those in the above embodiment, and are dummy nozzles. This makes it possible to neutralize the crosstalk vibration between the nozzles generated by simultaneous ejection.

The printing apparatus and printing method of the present invention can alleviate changes in ejection speed due to crosstalk from adjacent nozzles, changes in volume of ejected droplets, deviation in landing position of droplets, etc., and improve printing quality. can. Therefore, the printing apparatus and printing method of the present invention include, for example, coating of a light emitting layer of an organic EL display panel, coating of decorative ink or resin encapsulating ink using UV curable ink, coating of conductive ink, and cosmetics. It can also be applied to the application of water-based inks for applications.

1 board 2 pixel cell 3 coated image 4a ejection pixel 4b delayed ejection pixel 4c non-ejection pixel 4d delayed non-ejection pixel 5 print data retention memory 6 moving stage 7 position detector 8 ejection timing generator 9 drive waveform signal generator 9a reference ejection Waveform 9b Delayed ejection waveform 9c Reference non-ejection tickle waveform 9d Delayed non-ejection tickle waveform 10 Nozzle drive controller 11, 11a, 11b, 11c, 20 Ink head 12 Nozzle 14, 18 Ink chamber 15, 16, 17 Squeeze flow path 30 Actuator 40 Supply port 41 Discharge port

Claims (6)

A printing device that prints an image on an object using a plurality of nozzles arranged in a row and controlling the ejection of droplets based on a predetermined waveform.
A generation unit that generates a reference discharge waveform or a delayed discharge waveform having a predetermined delay amount with respect to the reference discharge waveform.
A control unit that assigns the reference discharge waveform or the delayed discharge waveform to the discharge nozzle that discharges the droplets among the plurality of nozzles based on the information of the image read from the predetermined storage unit. Have and
The control unit
Of the discharge nozzle group including two or more adjacent discharge nozzles
The reference discharge waveform is assigned to the 2nth nozzle (n is an odd number) and the 2n + 1st nozzle.
The delayed discharge waveform is assigned to the 2mth nozzle (m is an even number) and the 2m + 1st nozzle.
moreover,
The generating part is
A reference non-discharge tickle waveform that generates a tickle vibration having the same phase as the reference discharge waveform and the direction of displacement is opposite to the reference discharge waveform is generated.
The control unit
The reference non-discharge tickle waveform is assigned to the first non-discharge nozzle that is adjacent to one end of the discharge nozzle group and does not discharge droplets.
Printing equipment. The generating part is
A delayed non-discharge tickle waveform having a predetermined delay amount with respect to the reference non-discharge tickle waveform is generated.
The control unit
The reference non-discharge tickle waveform or the delayed non-discharge tickle waveform is assigned to the second non-discharge nozzle that is adjacent to the other end of the discharge nozzle group and does not discharge droplets.
The printing apparatus according to claim 1 . The control unit
When the reference discharge waveform is assigned to the nozzle located second from the second non-discharge nozzle group in the discharge nozzle group, the reference non-discharge tickle waveform is assigned to the second non-discharge nozzle. ,
When the delayed discharge waveform is assigned to the nozzle located second from the second non-discharge nozzle group in the discharge nozzle group, the delayed non-discharge tickle waveform is assigned to the second non-discharge nozzle. ,
The printing apparatus according to claim 2 . The delay amount is in the range of 0.5 to 1.5 times the resonance period of the meniscus of the droplet.
The printing apparatus according to any one of claims 1 to 3 . A printing method for printing an image on an object using a plurality of nozzles arranged in a row and controlling the ejection of droplets based on a predetermined waveform.
The first step of generating a reference discharge waveform or a delayed discharge waveform having a predetermined delay amount with respect to the reference discharge waveform.
A second step of assigning the reference discharge waveform or the delayed discharge waveform to the discharge nozzle that discharges the droplet among the plurality of nozzles based on the information of the image read from the predetermined storage unit. Have,
In the second step,
Of the discharge nozzle group including two or more adjacent discharge nozzles
The reference discharge waveform is assigned to the 2nth nozzle (n is an odd number) and the 2n + 1st nozzle.
The delayed discharge waveform is assigned to the 2mth nozzle (m is an even number) and the 2m + 1st nozzle.
Further, a third step of generating a reference non-discharge tickle waveform that generates a tickle vibration having the same phase as the reference discharge waveform and the direction of displacement is opposite to the reference discharge waveform.
A fourth step of assigning the reference non-discharge tickle waveform to a first non-discharge nozzle adjacent to one end of the discharge nozzle group and not ejecting a droplet is included.
Printing method. In the third step,
Further, a delayed non-discharge tickle waveform having a predetermined delay amount with respect to the reference non-discharge tickle waveform is generated.
In the fourth step,
The reference non-discharge tickle waveform or the delayed non-discharge tickle waveform is assigned to the second non-discharge nozzle that is adjacent to the other end of the discharge nozzle group and does not discharge droplets.
The printing method according to claim 5.

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