JP2021109362A - Method for setting component proportion ratio of droplets, droplet discharge device, and inkjet printer - Google Patents

Abstract

To provide a method for setting a component proportion ratio of droplets, that allows a suitable component proportion ratio of droplets to be easily set in a liquid discharge device for discharging droplets of a plurality of sizes.SOLUTION: In a method for setting a component proportion ratio of droplets according to the present invention, a first droplet to the m-th droplet (m being a natural number 3 or higher) are discharged. A component proportion ratio Rs of the first droplet becomes zero at a point where the total liquid amount Qi attains the maximum amount Qmax, after increasing to a point Q1 where the total liquid amount Qi attains the first liquid amount Q1. A component proportion ratio Rm of the n-th droplet (n being all natural numbers equal to 2 or higher but less than m) becomes zero at a point where the total liquid amount Qi attains the maximum amount Qmax, after increasing from a point Q1 where the component proportion ratio Rs of the (n-1)th droplet is maximal to a point Q2 where the total sum of the component proportion ratios Rs, Rm of the first droplet to the n-th droplet attains the maximum value Rmax. A component proportion ratio Rl of the m-th droplet increases from the point Q2 where the component proportion ratio Rm of the (m-1)th droplet is maximal to a point where the total liquid amount Qi attains the maximum amount Qmax.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for setting a composition ratio of droplets, a liquid ejection device, and an inkjet printer provided with the liquid ejection device.

Conventionally, a liquid discharge device for discharging a liquid has been known. Such a liquid ejection device is provided in, for example, an inkjet printer that ejects ink as a liquid. Among the liquid ejection devices provided in inkjet printers and the like, there are liquid ejection devices capable of simultaneously ejecting a plurality of types of droplets having different sizes. For example, Patent Document 1 discloses a liquid ejection device capable of forming three or more ink droplets having different sizes, and an inkjet printer provided with such a liquid ejection device.

In the liquid ejection device capable of forming a plurality of droplets having different sizes as described above, the composition ratio of each droplet is changed according to the amount of liquid ejected. For example, in the case of a liquid ejection device that ejects droplets of three sizes of small droplets, medium droplets, and large droplets, when the discharge amount of the liquid is small, the droplets are composed of only small droplets. As the amount of liquid discharged increases, medium droplets are added to the droplets. At that time, in some cases, the amount of droplets may be reduced. As the amount of liquid discharged increases, large droplets are added to the droplets. At that time, in some cases, the amount of small droplets or medium droplets may be reduced. The composition ratios of the small droplets, the medium droplets, and the large droplets are thus adjusted according to the discharge amount of the droplets.

Japanese Unexamined Patent Publication No. 2017-159463

In the liquid ejection device capable of forming a plurality of droplets having different sizes as described above, the liquid ejection quality is adjusted by changing the composition ratio of the plurality of droplets. For example, in the case of a liquid ejection device that ejects droplets of three sizes of small droplets, medium droplets, and large droplets, a banding problem is likely to occur when the discharged liquid is composed of only small droplets. Banding is a problem in which streaky unevenness occurs in the distribution of droplets. Further, when the composition ratio of large droplets is high in the discharged liquid, problems of lumps and graininess are likely to occur. Dama is an uneven distribution of droplets in which the dense portion of the droplets is conspicuous. The defect in graininess is uneven distribution of droplets in which the portion where the density of droplets is low is conspicuous. In the liquid discharge device, the composition ratio of a plurality of droplets is adjusted in order to minimize such a problem in a wide range.

Conventionally, the setting of the composition ratio of a plurality of droplets as described above has been performed by repeating the change of the composition ratio and the confirmation of the result. This change in composition ratio and confirmation of the result are repeated until a composition ratio of less problematic droplets is found over a wide range of liquid discharge amount. Therefore, it takes a lot of man-hours and time to set a suitable composition ratio.

The present invention has been made in view of this point, and an object of the present invention is to create a composition ratio of droplets in which a suitable composition ratio of droplets can be easily set in a liquid ejection device that ejects droplets of a plurality of sizes. It is to provide a setting method. Another object of the present invention is to provide a liquid discharge device capable of realizing such a method. Furthermore, it is to provide an inkjet printer provided with such a liquid ejection device.

The method for setting the composition ratio of the droplets disclosed herein is the first liquid in a liquid ejection device capable of forming first droplets to mth droplets (m is a natural number of 3 or more) having different sizes. This is a method of setting the composition ratio of each droplet according to the total amount of liquid, which is the total amount of liquid from the droplet to the mth droplet. The size of the first droplet to the mth droplet is set so as to increase in the order of the first droplet to the mth droplet. The composition ratio of the first droplet is increased to a point where the total liquid amount reaches a predetermined first liquid amount, and then becomes zero at a point where the total liquid amount reaches a predetermined maximum amount. Is set to decrease to. The composition ratio of the nth droplet (n is all natural numbers of 2 or more and less than m) is from the first droplet to the nth droplet from the point where the composition ratio of the (n-1) droplet is maximum. After the total of the constituent ratios of the above increases to a point where a predetermined maximum value is reached, the total amount of the liquid is set to decrease so as to become zero at the point where the maximum amount is reached. The composition ratio of the m-th droplet is set so as to increase from the point where the composition ratio of the (m-1) droplet is maximum to the point where the total liquid amount reaches the maximum amount.

Further, the liquid ejection device disclosed herein includes an ejection head capable of simultaneously forming first droplets to mth droplets (m is a natural number of 3 or more), and a control device for controlling the ejection head. There is.
The control device includes a first registration unit, a second registration unit, a third registration unit, a fourth registration unit, a calculation unit, and a discharge control unit. The sizes of the first droplet to the mth droplet are registered in the first registration unit. In the second registration unit, the maximum value of the total of the composition ratios of the first droplet to the mth droplet is registered. In the third registration unit, the maximum amount of the total liquid amount, which is the total of the liquid amounts of the first droplet to the mth droplet, is registered. In the fourth registration unit, the first liquid amount with respect to the total liquid amount is registered. The calculation unit calculates the composition ratio of the first droplet to the mth droplet according to the total amount of liquid. The discharge control unit discharges the first droplet to the m-th droplet from the discharge head based on the composition ratio of the first droplet to the m-th droplet calculated by the calculation unit.
The size of the first droplet to the mth droplet is set so as to increase in the order of the first droplet to the mth droplet. The composition ratio of the first droplet calculated by the calculation unit is increased until the total liquid amount reaches the first liquid amount, and then becomes zero at the point where the total liquid amount reaches the maximum amount. It is configured to decrease to. The composition ratio of the nth droplet (n is all natural numbers of 2 or more and less than m) calculated by the calculation unit is the first from the point where the composition ratio of the (n-1) droplet is maximum. After the total composition ratio of the droplet to the nth droplet increases to the point where the maximum value is reached, the total liquid amount is reduced to zero at the point where the maximum amount is reached. .. The composition ratio of the m-th droplet calculated by the calculation unit is increased from the point where the composition ratio of the (m-1) droplet is maximum to the point where the total liquid amount reaches the maximum amount. It is configured in.

According to the method for setting the composition ratio of the droplets and the liquid ejection device, the size of the first droplet to the mth droplet as a constant, the maximum amount of the total liquid amount, and the maximum of the total composition ratio of each droplet. By setting the value and the amount of the first liquid as a variable, the composition ratio of each droplet according to the total amount of liquid can be uniquely obtained. Further, according to the method for setting the composition ratio of the droplets and the liquid ejection device, if the ejection quality of the liquid is adjusted to a suitable quality in the region where the total liquid amount is equal to or less than the first liquid amount, the total liquid amount becomes the first. Suitable discharge quality is achieved even in the region where the amount of liquid is exceeded. Therefore, the setter can easily set a suitable composition ratio of each droplet only by determining the amount of the first liquid.

It is a perspective view of the inkjet printer which concerns on one Embodiment. It is a front view which shows the main part of an inkjet printer. It is a partial cross-sectional view of the vicinity of a nozzle of a discharge head. It is a waveform figure which shows an example of the drive signal for ejecting S drop, M drop, and L drop. It is a block diagram of an inkjet printer. It is a chart which shows the relationship between the total ink amount and the composition ratio of each ink drop.

Hereinafter, embodiments of the liquid ejection device according to the present invention and an inkjet printer provided with the same will be described with reference to the drawings. The embodiments described herein are, of course, not intended to specifically limit the present invention. In addition, members and parts that perform the same action are designated by the same reference numerals, and duplicate explanations are omitted or simplified.

FIG. 1 is a perspective view of an inkjet printer 10 according to an embodiment of the present invention. FIG. 2 is a front view showing a main part of the inkjet printer 10. In FIGS. 1 and 2, the symbols L and R indicate left and right, respectively. The symbols F and Rr indicate front and back, respectively. However, these are merely directions for convenience of explanation, and do not limit the installation mode of the inkjet printer 10.

The inkjet printer 10 is for printing on the recording medium 5. The recording medium 5 is an object on which ink is ejected. The recording medium includes not only paper such as plain paper, but also resin materials such as polyvinyl chloride (PVC) and polyester, and various materials such as aluminum, iron, and wood.

The inkjet printer 10 includes a casing 2 and a guide rail 3 arranged in the casing 2. The guide rail 3 extends in the left-right direction. A carriage 1 provided with a discharge head 15 for discharging ink is engaged with the guide rail 3. The carriage 1 reciprocates in the left-right direction (scanning direction) along the guide rail 3 by the carriage moving mechanism 8. The carriage moving mechanism 8 has pulleys 19b and 19a arranged on the left end side and the right end side of the guide rail 3. A carriage motor 8a is connected to the pulley 19a. The carriage motor 8a may be connected to the pulley 19b. The pulley 19a is driven by the carriage motor 8a. An endless belt 6 is wound around both pulleys 19a and 19b, respectively. The carriage 1 is fixed to the belt 6. When the pulleys 19a and 19b rotate and the belt 6 travels, the carriage 1 moves in the left-right direction.

The recording medium 5 is conveyed in the paper feed direction by a paper feed mechanism (not shown). Here, the paper feed direction is the front-back direction. A platen 4 that supports the recording medium 5 is provided in the casing 2. The platen 4 is provided with a grit roller (not shown). A pinch roller (not shown) is provided above the grit roller. The grit roller is connected to the feed motor 7 (see FIG. 5). The grit roller is driven by the feed motor 7 and rotates. When the grit roller rotates with the recording medium 5 sandwiched between the grit roller and the pinch roller, the recording medium 5 is conveyed in the front-rear direction.

The inkjet printer 10 includes a plurality of ink cartridges 11. Inks of different colors are stored in the plurality of ink cartridges 11. For example, the inkjet printer 10 includes five ink cartridges 11 for storing cyan ink, magenta ink, yellow ink, black ink, and white ink, respectively.

The ejection head 15 is provided for each color of ink. The ejection head 15 of each color and the ink cartridge 11 are connected by an ink supply path 12. The ink supply path 12 is an ink flow path that supplies ink from the ink cartridge 11 to the ejection head 15. The ink supply path 12 is composed of, for example, a flexible tube. A liquid feeding pump 13 is provided in the ink supply path 12. However, the liquid feed pump 13 is not always necessary and can be omitted. A part of the ink supply path 12 is covered with a cable protection guide device.

The ejection head 15 ejects ink toward the recording medium 5 and forms ink dots on the recording medium 5. By arranging a large number of these dots, an image or the like is formed on the recording medium 5. The ejection head 15 is provided with a plurality of nozzles 25 (see FIG. 3) for ejecting ink on a surface facing the recording medium 5 (lower surface of the ejection head 15 in this embodiment).

FIG. 3 is a partial cross-sectional view of the discharge head 15 in the vicinity of one nozzle 25. The discharge head 15 includes a hollow case 21 having an opening 21a and a diaphragm 22 attached to the case 21 so as to close the opening 21a. The diaphragm 22, together with the case 21, partitions the pressure chamber 23 in which ink is stored. The diaphragm 22 partitions a part of the pressure chamber 23. The diaphragm 22 is elastically deformable inside and outside the pressure chamber 23. The diaphragm 22 is configured to be deformable so as to increase and decrease the volume of the pressure chamber 23. The diaphragm 22 is typically a resin film or metal leaf.

The case 21 is formed with an ink inflow port 24 into which ink flows. The ink inlet 24 may be connected to the pressure chamber 23, and the position of the ink inlet 24 is not limited at all. Ink is supplied from the ink cartridge 11 to the pressure chamber 23 through the ink inlet 24, and the ink is stored. The nozzle 25 is formed on the lower surface 21b of the case 21.

The actuator 26 is in contact with the surface of the diaphragm 22 opposite to the pressure chamber 23 side. The actuator 26 here is a piezoelectric element. A part of the actuator 26 is fixed to the fixing member 29. The actuator 26 is connected to the control device 100 via a flexible cable 27. A signal is supplied to the actuator 26 via the flexible cable 27. In the present embodiment, the actuator 26 is a laminate in which a piezoelectric material and a conductive layer are alternately laminated. The actuator 26 expands or contracts when receiving a signal from the control device 100, and functions to elastically deform the diaphragm 22 to the outside or the inside of the pressure chamber 23. Here, a piezo element (PZT) in a longitudinal vibration mode is adopted. The PZT in the longitudinal vibration mode is expandable and contractible in the stacking direction. For example, it contracts when discharged and expands when charged. However, the type of the actuator 26 is not particularly limited.

In the discharge head 15 having such a configuration, the actuator 26 contracts, for example, by lowering the potential of the actuator 26 from the reference potential. Then, following this, the diaphragm 22 is elastically deformed from the initial position to the outside of the pressure chamber 23, and the pressure chamber 23 expands. The expansion of the pressure chamber 23 means that the volume of the pressure chamber 23 increases due to the deformation of the diaphragm 22. Next, by increasing the potential of the actuator 26, the actuator 26 extends in the stacking direction. As a result, the diaphragm 22 is elastically deformed inside the pressure chamber 23, and the pressure chamber 23 contracts. The contraction of the pressure chamber 23 means that the volume of the pressure chamber 23 becomes smaller due to the deformation of the diaphragm 22. Due to the expansion and contraction of the pressure chamber 23, the pressure in the pressure chamber 23 fluctuates. Due to the pressure fluctuation in the pressure chamber 23, the ink in the pressure chamber 23 is pressurized and discharged from the nozzle 25. After that, by returning the potential of the actuator 26 to the reference potential, the diaphragm 22 returns to the initial position and the pressure chamber 23 expands. At this time, ink flows into the pressure chamber 23 from the ink inflow port 24.

The ejection head 15 is configured to be capable of forming a plurality of ink droplets having different sizes at the same time. Here, the discharge head 15 discharges S droplets, M droplets, and L droplets having different sizes from each other. The ejection head 15 ejects ink droplets while changing the composition ratio of S droplets, M droplets, and L droplets according to the total ink amount of S droplets, M droplets, and L droplets (hereinafter referred to as total ink amount). do. The composition ratio of S drops, M drops, and L drops is commanded by the control device 100.

FIG. 4 is a waveform diagram showing an example of a drive signal for ejecting S droplets, M droplets, and L droplets. As shown in FIG. 4, the inkjet printer 10 generates a drive signal including five drive pulses P1 to P5 for each drive cycle. When forming the L droplet, the control device 100 supplies all the drive pulses P1 to P5 to the actuator 26. When forming M drops, the control device 100 supplies the actuator 26 with the third drive pulse P3 and the fifth drive pulse P5. When forming the S drop, the control device 100 supplies only the fifth drive pulse P5 to the actuator 26. However, the drive signal shown in FIG. 4 is only an example, and the mode of the drive signal is not limited.

The control device 100 is electrically connected to the feed motor 7 of the paper feed mechanism, the carriage motor 8a of the carriage movement mechanism 8, the liquid feed pump 13, and the discharge head 15. The control device 100 controls these operations. The control device 100 is typically a computer. The control device 100 includes, for example, an interface (I / F) that receives print data or the like from an external device such as a host computer, a central processing unit (CPU) that executes instructions of a control program, and a program executed by the CPU. It is provided with a ROM for storing the program, a RAM used as a working area for deploying the program, and a storage device such as a memory for storing the program and various data. The control device 100 is connected to the operation panel 150 (see FIG. 1). The operation panel 150 is a panel for the user to check the state of the inkjet printer 10 and make various settings. Although not shown, the operation panel 150 includes a display for displaying an operation screen and input keys.

FIG. 5 is a block diagram of the inkjet printer 10. As shown in FIG. 5, the control device 100 includes a configuration ratio setting unit 110 and a discharge control unit 120. The composition ratio setting unit 110 includes a first registration unit 111, a second registration unit 112, a third registration unit 113, a fourth registration unit 114, an input unit 115, and a calculation unit 116. The control device 100 may include other processing units, but illustration and description thereof will be omitted here.

The sizes of S droplets, M droplets, and L droplets are registered in the first registration unit 111. The sizes of the S drop, the M drop, and the L drop are set to increase in this order. The sizes of the S, M, and L drops registered in the first registration unit 111 are, here, the standard weights of the S, M, and L drops discharged from the discharge head 15. .. The standard weight of S, M, and L drops is determined, for example, by actually measuring the weight of the discharged S, M, and L drops. The size of the S drop, the M drop, and the L drop registered in the first registration unit 111 sets the composition ratio of the S drop, the M drop, and the L drop according to the total amount of ink in the calculation unit 116. Used as a constant for.

In the second registration unit 112, the maximum value of the total of the composition ratios of S drops, M drops, and L drops is registered. The composition ratio of ink droplets corresponds to the number of ink droplets ejected per unit area. In the present embodiment, the maximum value of the total composition ratio of S droplets, M droplets, and L droplets is set to 100%. However, where to set the standard (100%) of the composition ratio of S drops, M drops, and L drops is arbitrary, for example, the standard is set so that the maximum value exceeds 100% or falls below 100%. (100%) may be set. The total of the composition ratios of S drops, M drops, and L drops is set to be equal to or less than the above maximum value. Here, the number of ink droplets corresponding to the maximum value is set to the maximum number of ink droplets that the ejection head 15 can eject per unit area. In the case of multi-pass printing, the number obtained by multiplying the maximum number of ink droplets that can be ejected per unit area in one pass by the number of passes corresponds to the above maximum value.

The maximum amount of total ink is registered in the third registration unit 113. In the present embodiment, the maximum amount of total ink is set to the amount of ink when the composition ratio of L droplets is the maximum value (100%). In other words, the maximum amount of total ink is set to the amount of ink when all the nozzles 25 eject L droplets. When the total ink amount is the maximum amount, the ink amounts of S drops and M drops are both 0%. The maximum amount of the total ink amount corresponds to the maximum density of printing. The total amount of ink is expressed as a ratio with the maximum amount as 100%. The total amount of ink corresponds to the density relative to the maximum density of printing.

The first ink amount with respect to the total ink amount is registered in the fourth registration unit 114. As will be described in detail later, when the total ink amount is less than the first ink amount in the region where the total ink amount is small, the ejected ink is composed of only S droplets. When the total amount of ink becomes equal to or more than the first amount of ink, M drops are added to the composition of the ejected ink, and the composition ratio of S drops starts to decrease. The inkjet printer 10 according to the present embodiment is configured so that the user can change the first ink amount. The control device 100 includes an input unit 115 configured to be able to input the first ink amount. The input unit 115 displays, for example, an operation screen for inputting the first ink amount on the operation panel 150 of the inkjet printer 10. The fourth registration unit 114 is configured to register the first ink amount input by the input unit 115. The method for determining the first ink amount will be described later.

The calculation unit 116 calculates the composition ratio of S drops, M drops, and L drops according to the total amount of ink. Here, the calculation unit 116 continuously calculates the composition ratio of S drops, the composition ratio of M drops, and the composition ratio of L drops when the total amount of ink is 0% to 100%.

As will be described in detail later, the calculation unit 116 sets the composition ratio of the S droplets so as to increase until the total ink amount reaches the first ink amount. The composition ratio of the S droplet calculated by the calculation unit 116 becomes maximum at the point where the total ink amount becomes the first ink amount. The composition ratio of S droplets calculated by the calculation unit 116 becomes maximum and then decreases as the total ink amount increases. Specifically, the composition ratio of S drops decreases to zero at the point where the total ink amount reaches the maximum amount (100%).

Further, the calculation unit 116 increases the composition ratio of the M drops from the point where the composition ratio of the S drops is maximum (the point where the total ink amount becomes the first ink amount). The calculation unit 116 sets the composition ratio of the M drops so that the composition ratio of the M drops increases until the total of the composition ratios of the S drops and the M drops reaches the maximum value (100%). The composition ratio of M drops becomes the maximum at the point where the total of the composition ratios of S drops and M drops reaches the maximum value (100%). The composition ratio of M droplets calculated by the calculation unit 116 becomes maximum and then decreases as the total ink amount increases. Specifically, the composition ratio of M drops decreases to zero at the point where the total ink amount reaches the maximum amount (100%). This will also be described in detail later.

The calculation unit 116 sets the composition ratio of the L droplet to increase from the time when the composition ratio of the M droplet becomes maximum. The composition ratio of L droplets calculated by the calculation unit 116 increases until the total ink amount reaches the maximum amount (100%). Therefore, at the point where the total amount of ink is 100%, the ejected ink is composed of only L droplets, and the L droplets are ejected at the maximum density that can be ejected. This will also be described in detail later.

The discharge control unit 120 discharges the S drops, the M drops, and the L drops from the discharge head 15 based on the composition ratio of the S drops, the M drops, and the L drops calculated by the calculation unit 116.

Hereinafter, a procedure for setting the composition ratios of S drops, M drops, and L drops according to the total amount of ink by the calculation unit 116 will be described. In a liquid ejection device capable of forming a plurality of ink droplets having different sizes as in the present embodiment, the print image quality is adjusted by changing the composition ratio of the plurality of ink droplets. FIG. 6 is a chart showing the relationship between the total amount of ink and the composition ratio of each ink droplet. The horizontal axis of FIG. 6 is the total ink amount Qi. The maximum amount Qmax of the total ink amount Qi is 100% of the horizontal axis in FIG. The vertical axis of FIG. 6 is the composition ratio of S droplets, M droplets, and L droplets. The composition ratio of S drops is indicated by Rs. The composition ratio of M drops is indicated by Rm. The composition ratio of L droplets is indicated by Rl. The maximum value Rmax of the composition ratio of the ink droplets is 100% on the vertical axis of FIG. The total of the composition ratio Rs of S drops, the composition ratio Rm of M drops, and the composition ratio Rl of L drops is set to be 100% or less. Hereinafter, the description will be made on the assumption that the total ink amount Qi is gradually increased from 0% to 100%.

As shown in FIG. 6, the composition ratio Rs of S drops, the composition ratio Rm of M drops, and the composition ratio Rl of L drops calculated by the calculation unit 116 are any when the total ink amount Qi is "0%". Is also "0%". When the total ink amount Qi is increased from this state, the composition ratio Rs of S droplets increases from 0%. The composition ratio Rm of M drops and the composition ratio Rl of L drops do not increase at this point. As shown in FIG. 6, the composition ratio Rs of the S droplet increases linearly until the total ink amount Qi reaches the first ink amount Q1. In other words, the total ink amount Qi is increased by increasing the composition ratio Rs of the S droplets up to the point where the total ink amount Qi reaches the first ink amount Q1.

The first ink amount Q1 is registered in advance in the fourth registration unit 114, but can be changed by the user. The user can change the first ink amount Q1 according to the desired print quality. Among the parameters used in the calculation in the calculation unit 116, the size of the S drop, the M drop, and the L drop, the maximum amount Qmax of the total ink amount Qi, and the maximum value Rmax of the total of the composition ratios of each drop are constants. Is. The first ink amount Q1 is a variable that can be changed by the user.

The first ink amount Q1 is determined based on, for example, the degree of banding and graininess appearing in the printed image. Banding is a problem in which streaky unevenness occurs in the distribution of ink dots on which ink droplets land. The banding streaks generally appear parallel to the scanning direction of the carriage 1 (here, the left-right direction). Banding is likely to occur when there are few types of ink droplets, especially when only one type of ink droplet is used. Further, banding is more noticeable when the total ink amount Qi is large (print density is high). Therefore, in the region where the total ink amount is from 0% to the first ink amount Q1, banding is likely to occur, and the degree of banding tends to be worse as the total ink amount Qi is larger. Therefore, the first ink amount Q1 is set to be equal to or less than the total ink amount Qi so that the banding is within an acceptable range. Further, the defect of graininess is ejection unevenness in which a portion having a low density of ink dots is conspicuous. The image of the portion where the graininess defect occurs looks coarser than that of the other portions. The first ink amount Q1 is set with a balance between banding and graininess. By setting the first ink amount Q1 in this way, both the banding and the graininess in the region where the total ink amount is from 0% to the first ink amount Q1 are within the permissible range.

When the first ink amount Q1 is set, the composition ratio Rs of S drops, the composition ratio Rm of M drops, and the composition ratio Rl of L drops according to the total ink amount Qi are uniquely calculated. As shown in FIG. 6, the composition ratio Rs of the S droplet starts to decrease from the point where the total ink amount Qi is the first ink amount Q1. The composition ratio Rs of the S droplet becomes the maximum value Rsmax when the total ink amount Qi is the first ink amount Q1. From there, the composition ratio Rs of the S droplets starts to decrease so as to become zero at the point where the total ink amount Qi becomes the maximum amount Qmax (the point where the total ink amount Qi becomes 100%). As shown in FIG. 6, the composition ratio Rs of the S droplets linearly decreases from the maximum value Rsmax to zero while the total ink amount Qi increases from the first ink amount Q1 to the maximum amount Qmax.

The composition ratio Rm of the M droplet starts to increase from the point where the total ink amount Qi becomes the first ink amount Q1. The composition ratio Rm of the M droplet is zero at the point where the total ink amount Qi is the first ink amount Q1. The composition ratio Rm of the M droplet increases from there as the total ink amount Qi increases. At this time, the total amount of ink of S drops and M drops is equal to the total amount of ink Qi. As shown in FIG. 6, in the region until the total ink amount Qi reaches the second ink amount Q2, the composition ratio Rs of the S droplet continues to decrease, and the composition ratio Rm of the M droplet continues to increase. Since the constituent ratio Rs of the S droplet decreases linearly, the constituent ratio Rm of the M droplet increases linearly.

When the total ink amount Qi reaches the second ink amount Q2, the sum of the composition ratio Rs of the S droplet and the composition ratio Rm of the M droplet becomes the maximum value Rmax (100%). At the same time, the composition ratio Rm of the M droplet becomes the maximum value Rmmax. When the total ink amount Qi is the second ink amount Q2, the total of the composition ratio Rmmax of M drops and the composition ratio Rs2 of S drops is 100%. From there, the composition ratio Rm of the M droplet starts to decrease so as to become zero at the point where the total ink amount Qi reaches the maximum amount Qmax. As shown in FIG. 6, the composition ratio Rm of M droplets linearly decreases from the maximum value Rmmax to zero while the total ink amount Qi increases from the second ink amount Q2 to the maximum amount Qmax.

The composition ratio Rl of the L droplet starts to increase from the point where the total ink amount Qi becomes the second ink amount Q2. The composition ratio Rl of the L droplet is zero at the point where the total ink amount Qi is the second ink amount Q2. The composition ratio Rl of the L droplet increases from there as the total ink amount Qi increases. At this time, the total amount of ink of S drops, M drops, and L drops is equal to the total ink amount Qi. As shown in FIG. 6, the composition ratio Rs of S drops and the composition ratio Rm of M drops continue to decrease, and the composition ratio Rl of L drops continues to increase until the total ink amount Qi reaches the maximum amount Qmax. Since the constituent ratio Rs of the S droplet and the constituent ratio Rm of the M droplet decrease linearly, the constituent ratio Rl of the L droplet increases linearly. The composition ratio Rl of the L droplet becomes the maximum value Rlmax at the point where the total ink amount Qi reaches the maximum amount Qmax (100%). Rlmax is here 100%. At this time, the constituent ratio Rs of the S droplet and the constituent ratio Rm of the M droplet are both 0%. At the point where the total ink amount Qi is the maximum amount Qmax, the ejected ink is composed of only L droplets, and the L droplets are ejected at the maximum density that the ejection head 15 can eject.

As described above, in the inkjet printer 10 according to the present embodiment, the composition ratio of each ink droplet according to the total ink amount Qi is calculated only by setting the first ink amount Q1. Conventionally, the composition ratio of a plurality of ink droplets has been set by repeating changing the composition ratio and confirming the result. This change of the composition ratio and confirmation of the result are repeated until a composition ratio with less problem is found over a wide range of the total ink amount, which requires a lot of man-hours and time. On the other hand, in the inkjet printer 10 according to the present embodiment, the composition ratio of each ink droplet according to the total ink amount Qi is calculated only by setting the first ink amount Q1. Therefore, the man-hours and time required for setting the composition ratio of each ink droplet can be significantly saved.

According to the settings of the S-drop composition ratio Rs, the M-drop composition ratio Rm, and the L-drop composition ratio Rl as shown in FIG. 6, the print image quality is improved for the following reasons (1) to (3). can do.

(1) In the chart shown in FIG. 6, the region where banding is particularly likely to occur is a region where the total ink amount Qi is equal to or less than the first ink amount Q1. In this region, since only S droplets are discharged, banding is likely to occur. However, banding has been confirmed to be acceptable in this area. Therefore, in the region where the total ink amount Qi is equal to or less than the first ink amount Q1, no problematic banding occurs. It has also been confirmed that the graininess is within the permissible range in this region.

(2) In the chart shown in FIG. 6, S drops are ejected until the total ink amount Qi reaches the maximum amount Qmax while reducing the composition ratio after the point where the total ink amount Qi becomes the first ink amount Q1. Continue to be done. Similarly, after the point where the total ink amount Qi becomes the second ink amount Q2, the M droplets continue to be ejected until the total ink amount Qi reaches the maximum amount Qmax while reducing the composition ratio. Therefore, the types of ink droplets constituting the ejected ink increase as the total ink amount Qi increases. Banding is likely to occur when there are few types of ink droplets, especially when only one type of ink droplet is used. Therefore, according to the setting of the composition ratio of the ink droplets, it is possible to suppress banding in the region where the total ink amount Qi is the first ink amount Q1 or more. Further, banding is more noticeable when the total ink amount Qi is large, but according to the setting of the composition ratio of the ink droplets, the types of ink droplets constituting the ejected ink increase as the total ink amount Qi increases. Therefore, banding can be further suppressed.

(3) In the chart shown in FIG. 6, the composition ratio Rm of the M droplet increases until the sum with the composition ratio Rs of the S droplet reaches the maximum value Rmax (100%). Discharge of the L droplet is started from this point. That is, within the range in which the total ink amount Qi can be realized without adding L drops, S drops and M drops are ejected, and L drops are not ejected. The start of ejection of L droplets is set to the latest as long as other conditions allow.

In ink ejection, problems such as lumps and graininess are likely to occur when the composition ratio Rl of L droplets in the ejected ink is high. Dama is ejection unevenness in which a portion having a high density of ink dots is conspicuous. The part where the lump is generated looks like white particles. As described above, the defect of graininess is ejection unevenness in which the portion where the density of ink dots is low is conspicuous. The problem of lumps and graininess tends to occur when the composition ratio Rs of S drops and the composition ratio Rm of M drops are small and the composition ratio Rl of L drops is large in the region where the total ink amount Qi is large.

According to the setting of the composition ratio of each ink droplet according to the present embodiment, the ejection start of the L droplet is set to the latest as long as other conditions allow. Therefore, L droplets are not discharged, and therefore there is a wide area where problems of lumps and graininess are unlikely to occur. In addition, the area where L droplets are discharged and problems of lumps and graininess are likely to occur is narrow. Therefore, the problem of lumps and graininess can be suppressed.

As shown in (1) to (3) above, according to the method for setting the composition ratio of ink droplets according to the present embodiment, the composition ratio of ink droplets having less problem in a wide range of the total ink amount Qi can be easily obtained. Can be set.

Further, in the present embodiment, the maximum amount Qmax of the total ink amount Qi is set to the ink amount when the composition ratio Rl of the L droplet is the maximum value Rmax (100%). According to such a setting, the maximum amount Qmax of the total ink amount Qi corresponds to the maximum amount of ink that can be ejected by the ejection head 15. For example, if S drops or M drops are ejected from some nozzles 25 at the maximum amount Qmax of the total ink amount Qi, the ejection head 15 can eject the maximum amount Qmax of the total ink amount Qi. It becomes smaller than the maximum amount of ink. In other words, with such a setting, the ability of the discharge head 15 cannot be maximized. However, according to the method for setting the composition ratio of ink droplets according to the present embodiment, the ability of the ejection head 15 can be maximized.

Further, in the present embodiment, the first ink amount Q1 is configured so that the user can change the setting. According to such a configuration, the user can easily adjust the print image quality by himself / herself. For example, the user can change the first ink amount Q1 to a small value when he / she wants to suppress the banding in the low density region and to make the composition ratio of the ink droplets so as to allow some lumps and graininess in the high density region. ..

The preferred embodiment of the present invention has been described above. However, the above embodiments are merely examples, and the present invention can be implemented in various other embodiments.

For example, in the above-described embodiment, the types of ink droplets are S droplets, M droplets, and L droplets. However, the types of ink droplets may be four or more. The method of calculating the composition ratio of each ink droplet in the above-described embodiment can be extended as follows. That is, when the composition ratio of each ink droplet is set in the liquid ejection device capable of forming the first ink droplet to the mth ink droplet (m is a natural number of 3 or more) having different sizes, the configuration of the first ink droplet is formed. The ratio is set to increase to a point where the total ink amount reaches a predetermined first ink amount and then decrease to zero at a point where the total ink amount reaches a predetermined maximum amount. Further, the composition ratio of the nth ink droplet (n is all natural numbers of 2 or more and less than m) is from the first ink droplet to the nth ink droplet from the point where the composition ratio of the (n-1) droplet is maximum. After the total of the composition ratios of the above increases to the point where the predetermined maximum value is reached, it is set to decrease so as to become zero at the point where the total ink amount reaches the maximum amount. The composition ratio of the m-th ink droplet is set so as to increase from the point where the composition ratio of the (m-1) th droplet is maximum to the point where the total ink amount reaches the maximum amount. According to the method of setting the composition ratio of the ink droplets, the same effect as that of the above-described embodiment can be obtained when there are three or more types of ink droplets.

Further, in the above-described embodiment, the composition ratio of the ink droplets is set by the inkjet printer 10, but it is not necessary. The calculation of the composition ratio of the ink droplets described above may be performed outside the inkjet printer 10 by the setter of the inkjet printer 10. The calculation result may only be registered in the inkjet printer 10. Therefore, the inkjet printer 10 does not have to include a calculation unit or an input unit for inputting the first ink amount Q1 by the user. Even by such a method, the same effect as that of the above-described embodiment can be obtained.

In the above embodiments, the liquid is ink, but is not limited thereto. The liquid discharged by the liquid discharge device may be, for example, a resin material, various liquid compositions containing a solute and a solvent (for example, a cleaning liquid), or the like.

In the above embodiment, the actuator is a piezoelectric element in the longitudinal vibration mode, but the actuator is not limited to this. The actuator may be a piezoelectric element in the lateral vibration mode. Further, the actuator is not limited to the piezoelectric element, and may be, for example, a magnetostrictive element or the like.

In the above-described embodiment, the liquid discharge device is a discharge head mounted on the inkjet printer and a control device thereof, but the liquid discharge device is not limited thereto. The liquid discharge device can be mounted on, for example, various manufacturing devices that employ an inkjet method, a measuring instrument such as a micropipette, and can be used for various purposes.

10 Inkjet printer 15 Discharge head 100 Control device 111 1st registration unit 112 2nd registration unit 113 3rd registration unit 114 4th registration unit 115 Input unit 116 Calculation unit 120 Discharge control unit Qi Total ink amount (total liquid amount)
Qmax Maximum amount of total ink (maximum amount of total liquid)
Q1 First ink amount (first liquid amount)
Composition ratio of Rs S droplet (composition ratio of first droplet)
Composition ratio of Rm M droplet (composition ratio of second droplet)
Composition ratio of Rl L droplet (composition ratio of third droplet)
Maximum value of the total Rmax composition ratio

Claims (8)

In a liquid ejection device capable of forming first droplets to mth droplets (m is a natural number of 3 or more) having different sizes, it is the total amount of liquids of the first droplets to the mth droplets. It is a method of setting the composition ratio of each droplet according to the total amount of liquid.
The size of the first droplet to the mth droplet is set so as to increase in the order of the first droplet to the mth droplet.
The composition ratio of the first droplet is increased to a point where the total liquid amount reaches a predetermined first liquid amount, and then becomes zero at a point where the total liquid amount reaches a predetermined maximum amount. Set to decrease to
The composition ratio of the nth droplet (n is all natural numbers of 2 or more and less than m) is from the first droplet to the nth droplet from the point where the composition ratio of the (n-1) droplet is maximum. After the total of the constituent ratios of the above increases to the point where the predetermined maximum value is reached, the total amount of the liquid is set to decrease to zero at the point where the maximum amount is reached.
The composition ratio of the m-th droplet is set so as to increase from the point where the composition ratio of the (m-1) droplet is maximum to the point where the total liquid amount reaches the maximum amount.
How to set the composition ratio of droplets. The maximum amount of the total liquid amount is set to the liquid amount when the composition ratio of the mth droplet is the maximum value.
The method for setting the composition ratio of droplets according to claim 1. The liquid discharged by the liquid discharge device is ink.
The method for setting the composition ratio of droplets according to claim 1 or 2. Discharge the ink onto a paper medium.
The method for setting the composition ratio of droplets according to claim 3. A discharge head capable of forming first to mth droplets (m is a natural number of 3 or more) at the same time,
A control device that controls the discharge head and
With
The control device is
The first registration unit in which the sizes of the first droplet to the mth droplet are registered, and
A second registration unit in which the maximum value of the total of the composition ratios of the first droplet to the mth droplet is registered, and
A third registration unit in which the maximum amount of the total liquid amount, which is the sum of the liquid amounts of the first droplet to the mth droplet, is registered, and
A fourth registration unit in which the first liquid amount for the total liquid amount is registered, and
An arithmetic unit that calculates the composition ratio of the first droplet to the mth droplet according to the total amount of liquid, and
A discharge control unit that discharges the first droplet to the m-th droplet from the discharge head based on the composition ratio of the first droplet to the m-th droplet calculated by the calculation unit.
With
The size of the first droplet to the mth droplet is set so as to increase in the order of the first droplet to the mth droplet.
The composition ratio of the first droplet calculated by the calculation unit is increased until the total liquid amount reaches the first liquid amount, and then becomes zero at the point where the total liquid amount reaches the maximum amount. Configured to reduce to
The composition ratio of the nth droplet (n is all natural numbers of 2 or more and less than m) calculated by the calculation unit is the first from the point where the composition ratio of the (n-1) droplet is maximum. After the total composition ratio of the droplet to the nth droplet increases to the point where the maximum value is reached, the total liquid amount is reduced to zero at the point where the maximum amount is reached.
The composition ratio of the m-th droplet calculated by the calculation unit is increased from the point where the composition ratio of the (m-1) droplet is maximum to the point where the total liquid amount reaches the maximum amount. Is composed of,
Liquid discharge device. The maximum amount of the total liquid amount is set to the liquid amount when the composition ratio of the mth droplet is the maximum value.
The liquid discharge device according to claim 5. The control device includes an input unit configured to be able to input the first liquid amount.
The fourth registration unit is configured to register the first liquid amount input by the input unit.
The liquid discharge device according to claim 5 or 6. The liquid discharge device according to any one of claims 5 to 7 is provided.
The liquid discharged from the discharge head is ink.
Inkjet printer.

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