Droplet discharge device and control device, control method and program for the same

Abstract

To appropriately form an image contour.SOLUTION: A control unit causes ink drops Dx, Dy to be discharged such that the number (4) of the ink drops Dx per pixel of the edge Ix of an image I is larger than that (1) of the ink drops Dy per pixel of the non-edge Iy of the image I and the amount (10 pL) of one of the ink drops Dx constituting one pixel of the edge Ix is smaller than that (40 pL) of one of the ink drops Dy constituting one pixel of the non-edge Iy.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a droplet ejection device equipped with a head having nozzles, a control device thereof, a control method, and a program. [Background technology]

[0002] Patent Document 1 discloses a droplet ejection device equipped with a head having nozzles. An image is formed on a recording medium by droplets ejected from the nozzles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-080497 Summary of the Invention [Problem to be solved by the invention]

[0004] A droplet discharged from a nozzle may separate into a main droplet and a satellite droplet that is smaller than the main droplet. The greater the volume of each droplet, the easier it is for the droplet to separate into the main droplet and the satellite droplet. The satellite droplet may land at a position different from the position where the main droplet lands due to the influence of the air current around the nozzle. Therefore, when a droplet that forms the edge of an image on a recording medium separates into a main droplet and a satellite droplet, the satellite droplet lands at a position different from the position where the main droplet landed, causing the outline of the image to become blurred.

[0005] An object of the present invention is to provide a droplet ejection device capable of appropriately forming the contours of an image, a control device thereof, a control method, and a program. [Means for solving the problem]

[0006] The droplet ejection device of the present invention comprises a head having a nozzle and a control unit, and the control unit is capable of executing a recording process for recording an image on a recording medium by ejecting droplets from the nozzle onto the recording medium based on image data, and is characterized in that in the recording process, droplets are ejected from the nozzle so that the number of droplets per pixel of the edge portion of the image related to the image data is greater than the number of droplets per pixel of a non-edge portion that is a part other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is less than the amount of droplets per droplet constituting one pixel of the non-edge portion.

[0007] The control device of the present invention is a control device that controls a droplet ejection device equipped with a head having a nozzle, and is capable of executing a recording process to record an image on a recording medium by ejecting droplets from the nozzle onto the recording medium based on image data, and is characterized in that in the recording process, droplets are ejected from the nozzle so that the number of droplets per pixel of the edge portion of the image related to the image data is greater than the number of droplets per pixel of the non-edge portion, which is a part other than the edge portion of the image, and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is less than the amount of droplets per droplet constituting one pixel of the non-edge portion.

[0008] The control method of the present invention is a control method for controlling a droplet ejection device equipped with a head having a nozzle, and is characterized in that a recording process is performed to record an image on a recording medium by ejecting droplets from the nozzle onto the recording medium based on image data, and in the recording process, droplets are ejected from the nozzle so that the number of droplets per pixel of the edge portion of the image related to the image data is greater than the number of droplets per pixel of a non-edge portion that is a part other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is less than the amount of droplets per droplet constituting one pixel of the non-edge portion.

[0009] The program according to the present invention includes a droplet ejection device including a head having nozzles, A program that functions as a recording means for recording an image on a recording medium by ejecting droplets from the nozzle onto the recording medium based on image data, wherein the recording means ejects droplets from the nozzle so that the number of droplets per pixel in the edge portion of the image related to the image data is greater than the number of droplets per pixel in the non-edge portion, which is a portion other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is less than the amount of droplets per droplet constituting one pixel of the non-edge portion. Effect of the Invention

[0010] According to the present invention, the amount of droplets per droplet is small at the edge of the image, so that droplets are less likely to separate. Also, although the density of the edge may be low simply because the amount of droplets per droplet is small, the number of droplets per pixel at the edge is large, so that the density of the edge can be prevented from being low. This allows the contour of the image to be properly formed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a plan view showing an overall configuration of a printer according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the head shown in FIG. [Diagram 3] FIG. 2 is a block diagram showing the electrical configuration of the printer in FIG. [Figure 4] 2 is a flow chart showing a program executed by a control device of the printer in FIG. 1. [Diagram 5] 2 is a schematic diagram showing an example of an image recorded on paper by the printer of FIG. 1, illustrating the number of ink droplets for each pixel of the image and the amount per droplet; [Figure 6] FIG. 6 is a schematic diagram corresponding to FIG. 5, showing an example of an image recorded on paper by a printer according to a second embodiment of the present invention, illustrating the number of ink droplets per pixel of the image and the amount per droplet. [Figure 7]FIG. 6 is a schematic diagram corresponding to FIG. 5, showing an example of an image recorded on paper by a printer according to a third embodiment of the present invention, illustrating the number of ink droplets per pixel of the image and the amount per droplet. [Figure 8] FIG. 11 is a flow chart showing a program executed by a control device of a printer according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the following description, the X and Y directions are horizontal directions, and the Z direction is vertical. The X and Y directions are perpendicular to the Z direction, and the X direction is perpendicular to the Y direction. The X direction corresponds to the first direction of the present invention, and the Y direction corresponds to the second direction of the present invention.

[0013] First Embodiment 1 is a first embodiment of a droplet ejection device according to the present invention. The printer 100 includes a head 10 having a plurality of nozzles N, a carriage 20 that holds the head 10, a movement mechanism 30 that moves the carriage 20 and the head 10, a platen 40 that supports paper P from below, a transport mechanism 50 that transports paper P, and a control device 90. The paper P is an example of a recording medium according to the present invention.

[0014] The nozzles N form four nozzle rows N1 to N4 aligned in the Y direction. Each of the nozzle rows N1 to N4 includes a plurality of nozzles N aligned in the X direction. The nozzles N that form the nozzle rows N1 to N4 are aligned in the Y direction. The nozzle row N1 is an example of the first nozzle group of the present invention, the nozzle row N2 is an example of the second nozzle group of the present invention, the nozzle row N3 is an example of the third nozzle group of the present invention, and the nozzle row N4 is an example of the fourth nozzle group of the present invention. In this embodiment, the nozzles N that form the four nozzle rows N1 to N4 eject the same type of ink droplets. The nozzles N that form the four nozzle rows N1 to N4 eject black ink droplets.

[0015] The movement mechanism 30 includes a pair of guides 31, 32 that support the carriage 20, and a belt 33 connected to the carriage 20. The guides 31, 32 and the belt 33 extend in the Y direction. When a carriage motor 30m (see FIG. 3) is driven under the control of the control device 90, the belt 33 runs, and the carriage 20 and the head 10 move in the Y direction or the negative Y direction along the guides 31, 32. As a result, the head 10 and the paper P move relatively in the Y direction or the negative Y direction.

[0016] The platen 40 is disposed below the carriage 20 and the head 10. The paper P is supported on the upper surface of the platen 40.

[0017] The transport mechanism 50 has two roller pairs 51 and 52. The head 10, the carriage 20, and the platen 40 are disposed between the roller pairs 51 and 52 in the X direction. When the transport motor 50m (see FIG. 3) is driven under the control of the control device 90, the roller pairs 51 and 52 rotate while holding the paper P therebetween, and the paper P is transported in the X direction.

[0018] As shown in FIG. 2, the head 10 includes a flow passage unit 12 and an actuator unit 13.

[0019] A plurality of nozzles N (see FIG. 1) open on the bottom surface of the flow path unit 12. The flow path unit 12 has a common flow path 12a that communicates with an ink tank (not shown), and individual flow paths 12b that are individual for each nozzle N. The individual flow paths 12b extend from the outlet of the common flow path 12a through pressure chambers 12p to the nozzles N. A plurality of pressure chambers 12p open on the top surface of the flow path unit 12.

[0020] The actuator unit 13 includes a metallic vibration plate 13a arranged on the upper surface of the flow path unit 12 so as to cover the multiple pressure chambers 12p, a piezoelectric layer 13b arranged on the upper surface of the vibration plate 13a, and a plurality of individual electrodes 13c arranged on the upper surface of the piezoelectric layer 13b so as to face each of the multiple pressure chambers 12p.

[0021] The vibration plate 13a and the individual electrodes 13c are electrically connected to a driver IC 14. The driver IC 14 maintains the potential of the vibration plate 13a at the ground potential, while changing the potential of the individual electrodes 13c. Specifically, the driver IC 14 generates a drive signal based on a control signal from the control device 90, and supplies the drive signal to the individual electrodes 13c via a signal line 14s. The control signal includes a waveform signal FIRE and a selection signal SIN. As a result, the potential of the individual electrodes 13c changes between a predetermined drive potential (VDD) and a ground potential (0V). At this time, the actuator 13x, which is a portion of the vibration plate 13a and the piezoelectric layer 13b sandwiched between each individual electrode 13c and each pressure chamber 12p, is deformed, thereby changing the volume of the pressure chamber 12p, applying pressure to the ink in the pressure chamber 12p, and ejecting an ink droplet from the nozzle N. The actuator 13x is provided for each individual electrode 13c, i.e., for each nozzle N, and can be independently deformed according to the potential supplied to the individual electrode 13c.

[0022] 3, the control device 90 includes a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, and an ASIC (Application Specific Integrated Circuit) 94. Of these, the CPU 91 and the ASIC 94 are examples of the control unit of the present invention.

[0023] The ROM 92 stores programs and data for the CPU 91 and ASIC 94 to perform various controls. The RAM 93 temporarily stores data used when the CPU 91 and ASIC 94 execute the programs. The control device 90 is communicably connected to a PC (personal computer) 200, and receives a recording command including image data from the PC 200. The CPU 91 and ASIC 94 execute a recording process based on the recording command.

[0024] In the recording process, the ASIC 94 drives the driver IC 14, the carriage motor 30m, and the transport motor 50m in accordance with commands from the CPU 91 and based on recording commands received from the PC 200, and alternates between a transport operation for transporting the paper P a predetermined distance in the X direction by the transport mechanism 50 and a scanning operation for ejecting ink droplets from the nozzles N while moving the carriage 20 and the head 10 in the Y direction or the minus Y direction. As a result, dots of ink droplets are formed on the paper P, and an image is recorded.

[0025] The ASIC 94 includes an output circuit 94a and a transfer circuit 94b.

[0026] The output circuit 94a generates a waveform signal FIRE and a selection signal SIN, and outputs these signals to the transfer circuit 94b for each recording cycle. One recording cycle is the time required for the paper P to move relative to the head 10 by a unit distance corresponding to the resolution of the image formed on the paper P, and corresponds to one pixel.

[0027] The waveform signal FIRE is a serial signal obtained by serializing four pieces of ejection data. The four pieces of ejection data indicate the potential of the individual electrode 13c, and differ from each other in the number of pulses that change the potential of the individual electrode 13c between the ground potential (0V) and the drive potential (VDD) in one recording period, the pulse width, etc. As a result, the four pieces of ejection data differ from each other in the amount of ink droplets ejected from the nozzle N in one recording period. The four pieces of ejection data include first ejection data indicating that the amount of ink droplets ejected from the nozzle N in one recording period is zero (no ejection: 0pl), second ejection data indicating that the amount of ink droplets ejected from the nozzle N in one recording period is small (5pl), third ejection data indicating that the amount of ink droplets ejected from the nozzle N in one recording period is medium (10pl), and fourth ejection data indicating that the amount of ink droplets ejected from the nozzle N in one recording period is large (40pl).

[0028] The selection signal SIN is a serial signal including selection data for selecting one of the four ejection data, and is generated for each actuator 13x and for each recording cycle based on the image data included in the recording command.

[0029] The transfer circuit 94b transfers the waveform signal FIRE and the selection signal SIN received from the output circuit 94a to the driver IC 14. The transfer circuit 94b has built-in LVDS (Low Voltage Differential Signaling) drivers corresponding to each of the above signals, and transfers each signal to the driver IC 14 as a pulse-shaped differential signal.

[0030] In the recording process, the ASIC 94 controls the driver IC 14 to generate a drive signal for each pixel based on the waveform signal FIRE and the selection signal SIN, and supplies the drive signal to the individual electrode 13c via the signal line 14s. As a result, the ASIC 94 ejects ink droplets from each of the multiple nozzles N toward the paper P according to the ejection data selected from the four ejection data for each pixel.

[0031] Next, the program executed by the control device 90 will be described with reference to FIG.

[0032] The CPU 91 of the control device 90 first determines whether or not a recording command has been received from the PC 200 (S1).

[0033] When the CPU 91 determines that it has not received a recording command (S1: NO), the CPU 91 determines whether or not a predetermined time has elapsed since the CPU 91 first determined S1 in the program (S2).

[0034] When it is determined that the predetermined time has elapsed (S2: YES), the CPU 91 executes an inspection process for inspecting nozzle N for non-ejection (S3).

[0035] In S3, the CPU 91 determines whether or not there is a non-ejection for each nozzle N included in the head 10, and stores information identifying the nozzles N determined to be non-ejection in the RAM 93. For example, the head 10 is placed at a predetermined inspection position, and the driver IC 14 is driven to cause all the nozzles N included in the head 10 to eject ink droplets onto the cap. Then, based on a change in the potential of an inspection electrode arranged in the cap, it is determined for each nozzle N whether or not positively charged ink droplets have landed on the cap, i.e., whether or not there is a non-ejection. The inspection position is, for example, a position where the head 10 is not aligned with the platen 40 in the Z direction.

[0036] If it is determined that the predetermined time has not elapsed (S2: NO), or after S3, the CPU 91 returns the process to S1.

[0037] When it is determined that a recording command has been received (S1: YES), the CPU 91 determines whether the image quality mode indicated by the recording command is a high image quality mode (S4).

[0038] In this embodiment, the image quality mode indicated by the recording command is either a high image quality mode or a normal image quality mode, which has a lower image quality than the high image quality mode. The normal image quality mode and the high image quality mode have different image resolutions. The high image quality mode corresponds to the first mode of the present invention, and the normal image quality mode corresponds to the second mode of the present invention.

[0039] If it is determined that the high image quality mode is selected (S4: YES), the CPU 91 executes a first data generation process (S5), which will be described later.

[0040] If it is determined that the image quality mode is not high quality mode (that is, the image quality mode is normal quality mode) (S4: NO), the CPU 91 executes a second data generation process (S6) which will be described later.

[0041] The first data generation process (S5) corresponds to the data generation process of the present invention. In S5, the CPU 91 generates ejection data so that the number of ink droplets per pixel in the edge part of the image related to the image data is greater than the number of ink droplets per pixel in the non-edge part, which is a part other than the edge part of the image and has the same density as the edge part, and the amount of ink droplets per pixel in the edge part is less than the amount of ink droplets per pixel in the non-edge part.

[0042] "Generating ejection data" means that the output circuit 94a of the ASIC 94 generates a selection signal SIN for each actuator 13x and for each recording period to select one ejection data that meets the conditions from among the four ejection data.

[0043] Here, the number of ink droplets and the amount per droplet for each pixel of image I will be described with reference to Fig. 5. In Fig. 5, one square corresponds to one pixel.

[0044] 5 on the paper P, the number of ink droplets Dx per pixel is "4" and the amount of each ink droplet Dx is "medium (10 pl)" in the edge portion Ix of the image I. The number of ink droplets Dy per pixel is "1" and the amount of each ink droplet Dy is "large (40 pl)" in the non-edge portion Iy of the image I.

[0045] In the example of FIG. 5, the total amount of ink droplets Dx per pixel in the edge portion Ix (10 pl×4) is the same as the total amount of ink droplets Dy per pixel in the non-edge portion Iy (40 pl).

[0046] 5, the potentials of the individual electrodes 13c corresponding to the four nozzles N are changed based on the third ejection data, causing medium (10 pl) ink droplets Dx to be ejected from each of the four nozzles N. The four nozzles N are nozzles N that belong to each of the four nozzle rows N1 to N4 (see FIG. 1) and are aligned in the Y direction.

[0047] 5, the potential of the individual electrode 13c corresponding to one nozzle N is changed based on the fourth ejection data, causing a "large (40 pl)" ink droplet Dy to be ejected from that one nozzle N. That one nozzle N is a nozzle belonging to one nozzle row (for example, nozzle row N1) of the four nozzle rows N1 to N4 (see FIG. 1).

[0048] The four ink droplets Dx that make up one pixel of the edge Ix may or may not overlap each other.

[0049] Whether or not each pixel of the image I constitutes an edge Ix may be determined as follows.

[0050] The CPU 91 checks the data on the amount of ink droplets for each pixel in the Y direction included in the ejection data, and if the amount of ink droplets switches from zero to small, medium, or large, it determines that the pixel at the transition portion constitutes the edge portion Ix.The CPU 91 also checks the data on the amount of ink droplets for each pixel in the X direction included in the ejection data, and if the amount of ink droplets switches from zero to small, medium, or large, it determines that the pixel at the transition portion constitutes the edge portion Ix.

[0051] Alternatively, the CPU 91 checks data relating to the density of each pixel in the Y direction, and if the density difference between two pixels adjacent in the Y direction is equal to or greater than a predetermined value, determines that the pixel with the higher density of the two pixels constitutes the edge portion Ix. The CPU 91 also checks data relating to the density of each pixel in the X direction, and if the density difference between two pixels adjacent in the X direction is equal to or greater than a predetermined value, determines that the pixel with the higher density of the two pixels constitutes the edge portion Ix.

[0052] The CPU 91 may appropriately select the number of scanning operations while the conveyance is stopped according to the image quality and the recording speed indicated by the recording command. For example, the CPU 91 may select the number of scanning operations as one for a certain image quality, and two or more for a higher image quality than the above image quality. Also, for example, the CPU 91 may select the number of scanning operations as one for a certain recording speed, and two or more for a higher image quality than the above image quality.

[0053] In the second data generation process (S6), the CPU 91 generates ejection data so that the number of ink droplets per pixel of the edge portion Ix is the same as the number of ink droplets per pixel of the non-edge portion Iy, and the amount of ink droplets per pixel of the edge portion Ix is the same as the amount of ink droplets per pixel of the non-edge portion Iy.

[0054] In S5 and S6, the CPU 91 generates ejection data based on the result information of the inspection process (S3) stored in the RAM 93 so as not to eject ink droplets from a non-ejecting nozzle that has been determined to be non-ejecting, and to eject ink droplets from a nozzle N that is aligned in the Y direction or the minus Y direction with the non-ejecting nozzle and that belongs to a nozzle row other than the nozzle row to which the non-ejecting nozzle belongs among the four nozzle rows N1 to N4. For example, if one nozzle N that belongs to the nozzle row N1 is determined to be non-ejecting and the nozzles N that belong to the nozzle rows N2 to N4 are determined to be not non-ejecting, the CPU 91 generates ejection data so as to eject ink droplets Dx, Dy from a nozzle N that belongs to the nozzle rows N2 to N4 and is aligned in the Y direction with the non-ejecting nozzle.

[0055] After S5 or S6, the CPU 91 executes a recording process (S7). In S7, the CPU 91 issues a command to the ASIC 94 to drive the driver IC 14, the carriage motor 30m, and the transport motor 50m, and alternately performs a transport operation in which the transport mechanism 50 transports the paper P a predetermined distance in the X direction, and a scanning operation in which the carriage 20 and the head 10 move in the Y direction or the minus Y direction while ejecting ink droplets from the nozzles N. In the scanning operation, ink droplets are ejected from the nozzles N so that the number of ink droplets Dx per pixel of the edge portion Ix (four) is greater than the number of ink droplets Dy per pixel of the non-edge portion Iy (one), and the amount of ink droplets Dx per pixel of the edge portion Ix (10pl) is less than the amount of ink droplets Dy per pixel of the non-edge portion Iy (40pl).

[0056] After S7, the CPU 91 ends the program.

[0057] As described above, according to this embodiment, in the recording process (S7), the CPU 91 ejects ink droplets Dx and Dy from the nozzle N so that the number (4) of ink droplets Dx per pixel of the edge portion Ix of the image I is greater than the number (1) of ink droplets Dy per pixel of the non-edge portion Iy of the image I, and the amount (10 pl) of the ink droplets Dx constituting one pixel of the edge portion Ix is less than the amount (40 pl) of the ink droplets Dy constituting one pixel of the non-edge portion Iy (see FIG. 5). In this case, the ink droplets Dx are less likely to separate in the edge portion Ix because the amount per droplet is small. In addition, although the density of the edge portion Ix may be low simply because the amount per droplet is small, the large number of ink droplets Dx per pixel of the edge portion Ix can suppress the density of the edge portion Ix from being low. This allows the contour of the image I to be properly formed.

[0058] The nozzles N form four nozzle rows N1 to N4 (see FIG. 1). The nozzles N forming the nozzle rows N1 to N4 are arranged in a line in the Y direction. In the recording process (S7), the CPU 91 ejects four ink droplets Dx forming the edge portion Ix of the image I from the nozzles N that belong to each of the four nozzle rows N1 to N4 (see FIG. 1) and are arranged in the Y direction. That is, as the nozzles that eject the ink droplets Dx that form the edge portion Ix of the image I, not only the nozzles N of the nozzle row N1 but also the nozzles N of the nozzle rows N2 to N4 can be used. This increases the variation in ejection patterns, and even if there is a non-ejecting nozzle, ink liquid can be ejected from the other nozzles to make up for the non-ejected ink droplets.

[0059] If the CPU 91 determines in the inspection process (S3) that one nozzle N belonging to any of the four nozzle rows N1 to N4 is non-ejecting and the nozzles N belonging to the other nozzle rows are not non-ejecting, then in the recording process (S7), the CPU 91 does not cause the non-ejecting nozzle to eject ink droplets, but causes the nozzles N belonging to the other nozzle rows to eject ink droplets. In this case, by not using the non-ejecting nozzle and using the nozzles with a stable ejection state, deterioration of image quality can be suppressed.

[0060] In the recording process (S7), the CPU 91 ejects ink droplets Dx and Dy from the nozzles N so that the total amount of ink droplets Dx per pixel in the edge portion Ix (10pl x 4) is equal to the total amount of ink droplets Dy per pixel in the non-edge portion Iy (40pl) (see FIG. 5). In this case, it is possible to suppress both separation of the ink droplets Dx at the edge portion Ix and a decrease in density in the edge portion Ix in a well-balanced manner.

[0061] In the case of a high-image-quality mode in which sharp edges are required, the CPU 91 executes a first data generation process (S5). This reduces the amount of ink droplets Dy that make up one pixel at the edge Ix and increases the number of ink droplets Dx per pixel, thereby properly forming the edges of the image I. On the other hand, in the case of a normal image-quality mode in which sharp edges are not as required as in the high-image-quality mode, the CPU 91 executes a second data generation process (S6) and does not perform the above-mentioned control. In this case, the control can be simplified compared to when the above control is performed uniformly regardless of the mode.

[0062] In the recording process (S7), the CPU 91 ejects ink droplets Dy from the nozzles N so that the number of ink droplets Dy per pixel in the non-edge portion Iy is "1" (see FIG. 5). If the number of ink droplets per pixel is two or more, the image may appear grainy due to variations in the ejection of the two or more ink droplets. Therefore, by setting the number of ink droplets Dy per pixel to one in the non-edge portion Iy, which does not cause blurred contours, the graininess in the image can be suppressed.

[0063] Prior to the recording process (S7), the CPU 91 executes data generation processes (S5, S6) to generate ejection data. In the first data generation process (S5), the CPU 91 generates ejection data so that the number of ink droplets per pixel of the edge portion Ix is greater than the number of ink droplets per pixel of the non-edge portion Iy, and the amount of ink droplets per pixel of the edge portion Ix is less than the amount of ink droplets per pixel of the non-edge portion Iy (see FIG. 5). In this case, control for appropriately forming the contour of the image I can be effectively achieved.

[0064] <Second embodiment> Next, a printer according to a second embodiment of the present invention will be described.

[0065] In the first embodiment (see FIG. 5), the amount per droplet of the four ink droplets Dx that form one pixel on the edge portion Ix is the same "medium (10 pl)".

[0066] In contrast, in the second embodiment (see FIG. 6), the three ink droplets Dx that make up one pixel of the edge Ix include one “medium (10 pl)” ink droplet Dx1 and two “small (5 pl)” ink droplets Dx.

[0067] When ejecting ink droplets Dx that form one pixel of the edge Ix, the CPU 91 first ejects ink droplets Dx1 from the nozzles N of the nozzle row N1, and then ejects ink droplets Dx2 from the nozzles N of the nozzle rows N2 and N3.

[0068] In this embodiment, the total amount of ink droplets Dx per pixel in the edge portion Ix (10 pl+5 pl×2) is less than the total amount of ink droplets Dy per pixel in the non-edge portion Iy (40 pl).

[0069] As described above, according to this embodiment, when the CPU 91 ejects ink droplets Dx constituting one pixel of the edge portion Ix in the recording process (S7), it first ejects ink droplets Dx1 from the nozzles N of the nozzle row N1, and then ejects ink droplets Dx2 (ink droplets Dx2 with a smaller amount than the ink droplets Dx1) from the nozzles N of the nozzle rows N2 and N3. That is, the ink droplets Dx1 land on the paper P first, and after the ink droplets Dx1 permeate the paper P, the ink droplets Dx2 land with a smaller amount than the ink droplets Dx1. In this case, it is possible to obtain a desired density while suppressing the total consumption of ink droplets Dx.

[0070] In the recording process (S7), the CPU 91 ejects ink droplets Dx, Dy from the nozzles N so that the total amount of ink droplets Dx per pixel in the edge portion Ix (10pl+5pl×2) is less than the total amount of ink droplets Dy per pixel in the non-edge portion Iy (40pl) (see FIG. 6). In this case, separation of the ink droplets Dx in the edge portion Ix can be more reliably suppressed.

[0071] <Third embodiment> Next, a printer according to a third embodiment of the present invention will be described.

[0072] In the first embodiment (see FIG. 5), each pixel in the image I is divided into two types: an edge portion Ix and a non-edge portion Iy, whereas in the third embodiment (see FIG. 7), each pixel in the image I is divided into three types: an edge portion Ix, a non-edge portion Iy, and a transition portion Iz. The transition portion Iz is a portion between the edge portion Ix and the non-edge portion Iy that has the same density as the edge portion Ix.

[0073] In this embodiment, in the edge portion Ix, the number of ink drops Dx per pixel is "4", and the volume of each ink drop Dx is "small (5 pl)". In the non-edge portion Iy, the number of ink drops Dy per pixel is "1", and the volume of each ink drop Dy is "large (40 pl)". In the transition portion Iz, the number of ink drops Dz per pixel is "3", and the volume of each ink drop Dz is "medium (10 pl)".

[0074] As described above, according to this embodiment, in the recording process (S7), the CPU 91 ejects ink droplets from the nozzle N so that the amount (10 pl) of each ink droplet Dx constituting one pixel of the transition portion Iz is less than the amount (40 pl) of each ink droplet Dy constituting one pixel of the non-edge portion Iy and is greater than the amount (5 pl) of each ink droplet Dx constituting one pixel of the edge portion Ix. In other words, the amount of each ink droplet constituting one pixel is gradually reduced from the non-edge portion Iy through the transition portion Iz to the edge portion Ix. This suppresses separation of ink droplets near the edge portion Ix and makes the contour of the image sharper.

[0075] <Fourth embodiment> Next, a printer according to a fourth embodiment of the present invention will be described.

[0076] In the first embodiment (see FIG. 4), when the CPU 91 determines that the image quality mode indicated by the recording command is the high image quality mode (S4: YES), it executes a first data generation process (S5).

[0077] In contrast to this, in the fourth embodiment (see FIG. 8), when the CPU 91 determines that the image related to the image data included in the recording command indicates text (S24: YES), it executes a first data generation process (S5).

[0078] In the present embodiment, the program executed by the control device 90 is the same as that in the first embodiment, except that the process of S4 in the program executed by the control device 90 is replaced with the process of S24.

[0079] When the CPU 91 determines that a recording command has been received (S1: YES), it determines whether or not an image related to the image data included in the recording command shows characters (S24: determination process).

[0080] If it is determined that the image indicates text (S24: YES), the CPU 91 executes a first data generation process (S5).

[0081] When it is determined that the image does not show characters (S24: NO), the CPU 91 executes a second data generation process (S6).

[0082] As described above, according to this embodiment, when recording characters that require sharp edges, the CPU 91 executes the first data generation process (S5). This reduces the amount of ink droplets Dy that form one pixel at the edge Ix and increases the number of ink droplets Dx per pixel, thereby properly forming the edges of the image I. On the other hand, when recording a photograph or the like other than characters, the CPU 91 executes the second data generation process (S6) and does not perform the above-mentioned control. In this case, the control can be simplified compared to when the above-mentioned control is performed uniformly regardless of the type of image.

[0083] <Fifth embodiment> Next, a printer according to a fifth embodiment of the present invention will be described.

[0084] In the first embodiment, in the recording process (S7), the CPU 91 ejects ink droplets Dx, Dy from the nozzle N so that the total amount of ink droplets Dx per pixel of the edge portion Ix (10pl x 4) is the same as the total amount of ink droplets Dy per pixel of the non-edge portion Iy (40pl) (see Figure 5).

[0085] In contrast, in the fifth embodiment, in the recording process (S7), the CPU 91 ejects ink droplets from the nozzles N so that the total amount of ink droplets Dx per pixel in the edge portion Ix is greater than the total amount of ink droplets Dy per pixel in the non-edge portion Iy. For example, in the edge portion Ix, the number of ink droplets Dx per pixel is "4", and the amount of each ink droplet Dx is "15 pl". In the non-edge portion Iy, the number of ink droplets Dy per pixel is "1", and the amount of each ink droplet Dy is "40 pl".

[0086] As described above, according to this embodiment, the CPU 91 can more reliably suppress a decrease in density of the edge portion Ix by ejecting ink droplets so that the total amount of ink droplets Dx per pixel of the edge portion Ix is greater than the total amount of ink droplets Dy per pixel of the non-edge portion Iy.

[0087] Sixth Embodiment Next, a printer according to a sixth embodiment of the present invention will be described.

[0088] In the first embodiment, the nozzles N constituting the four nozzle rows N1 to N4 each eject black ink droplets, that is, ink droplets of the same type.

[0089] In contrast, in the sixth embodiment, the nozzles N constituting nozzle row N1 eject black ink droplets, the nozzles N constituting nozzle row N2 eject yellow ink droplets, the nozzles N constituting nozzle row N3 eject magenta ink droplets, and the nozzles N constituting nozzle row N4 eject cyan ink droplets.

[0090] In this embodiment, in the recording process (S7), the CPU 91 causes the nozzles N belonging to the nozzle row N1 to eject ink droplets constituting one pixel of the non-edge portion Iy, and causes the nozzles N belonging to each of the nozzle rows N2 to N4 aligned in the Y direction to eject ink droplets constituting one pixel of the edge portion Ix. That is, a composite black image is recorded on the edge portion Ix by overlapping a yellow ink droplet ejected from one nozzle N belonging to the nozzle row N2, a magenta ink droplet ejected from one nozzle N belonging to the nozzle row N3, and a cyan ink droplet ejected from one nozzle N belonging to the nozzle row N4. Composite black is also called tricolor black or process black.

[0091] As described above, according to this embodiment, the contour of a black image can be appropriately formed using the existing four-color head 10.

[0092] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various design modifications are possible within the scope of the claims.

[0093] For example, in the first embodiment (see FIG. 5), one pixel of the edge portion Ix is formed by ink droplets Dx ejected from each of the four nozzles N, but this is not limited to this. For example, one pixel of the edge portion Ix may be formed by four ink droplets Dx ejected from one nozzle N. In this case, the CPU 91 may eject four ink droplets Dx from one nozzle N when the transport of the paper P is stopped and the movement of the head 10 and the carriage 20 is stopped.

[0094] The number of droplets per pixel in the non-edge portion is one droplet in the above embodiment, but is not limited to this and may be two or more droplets.

[0095] In the above embodiment, the high-image-quality mode and the normal-image-quality mode, which are modes based on image quality, are exemplified as the first and second modes, but are not limited thereto. For example, in a configuration in which the number of scanning operations is increased to increase the number of droplets per pixel at the edge, the printing speed may be slower in the first mode than in the second mode. In this case, of the low-speed mode and the high-speed mode, which are modes based on the printing speed, the low-speed mode may be the first mode, and the high-speed mode may be the second mode.

[0096] In the sixth embodiment, the nozzle row N1 is not used for recording the edge portion, but the nozzle row N1 may be used for recording the edge portion. For example, the CPU 91 may cause the nozzles N belonging to the nozzle row N1 to eject ink droplets that form one pixel of the non-edge portion Iy, and may cause the nozzles N belonging to each of the nozzle rows N1 to N4 that are aligned in the Y direction to eject ink droplets that form one pixel of the edge portion Ix.

[0097] The recording medium is not limited to paper, but may be cloth, a resin material, or the like.

[0098] The head is not limited to a serial type, but may be a line type.

[0099] The liquid droplet ejection device according to the present invention is not limited to a printer, but may be a facsimile, a copier, a multifunction machine, or the like.

[0100] The program according to the present invention can be distributed by recording it on a removable recording medium such as a flexible disk or a fixed recording medium such as a hard disk, or can be distributed via a communication line. [Explanation of symbols]

[0101] 10 Head 30 Moving mechanism 90 Control device 91 CPU (control unit) 94 ASIC (control unit) 100 Printer (droplet ejection device) Dx, Dy, Dz Ink droplets (droplets) N Nozzle N1 nozzle row (first nozzle group) N2 nozzle row (second nozzle group) N3 nozzle row (third nozzle group) N4 nozzle row (fourth nozzle group) P Paper (recording medium) I Image Ix Edge Iy non-edge Iz transition part J pixel

Claims

1. A head having a nozzle; A control unit, The control unit is A recording process is executed to record an image on a recording medium by discharging droplets from the nozzles onto the recording medium based on image data; a droplet ejection device that ejects droplets from the nozzle in such a manner that, in the recording process, the number of droplets per pixel in the edge portion of the image related to the image data is greater than the number of droplets per pixel in the non-edge portion, which is a portion other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel in the edge portion is less than the amount of droplets per pixel in the non-edge portion.

2. the head includes a first nozzle group including a plurality of the nozzles arranged in a first direction, and a second nozzle group including a plurality of the nozzles arranged in the first direction, the nozzles constituting the first nozzle group, and a plurality of the nozzles aligned in a second direction perpendicular to the first direction; a moving mechanism for relatively moving the head and the recording medium in the second direction, the nozzles constituting the second nozzle group eject the same type of droplets as the nozzles constituting the first nozzle group, The droplet ejection device according to claim 1, characterized in that, during the recording process, the control unit ejects droplets that constitute one pixel of the edge portion from one nozzle of the first nozzle group and one nozzle of the second nozzle group that is aligned with the one nozzle of the first nozzle group in the second direction.

3. The droplet ejection device according to claim 2, characterized in that, when ejecting droplets that constitute one pixel of the edge portion during the recording process, the control unit ejects a first amount of droplets from nozzles of one of the first nozzle group and the second nozzle group that first deposits droplets on the recording medium, and ejects a second amount of droplets smaller than the first amount from nozzles of the other nozzle group.

4. The control unit is A test process for testing the nozzles for non-ejection is executable, 3. The droplet ejection device according to claim 2, characterized in that if, in the inspection process, it is determined that the nozzles of one of the first nozzle group and the second nozzle group are not non-ejecting but the nozzles of the other nozzle group are non-ejecting, in the recording process, droplets are not ejected from the nozzles of the other nozzle group, but are ejected from the nozzles of the one nozzle group.

5. 2. The droplet ejection device according to claim 1, wherein the control unit, in the recording process, ejects droplets from the nozzles so that a total amount of droplets per pixel in the edge portion is the same as a total amount of droplets per pixel in the non-edge portion.

6. 2. The droplet ejection device according to claim 1, wherein the control unit, in the recording process, ejects droplets from the nozzles so that a total amount of droplets per pixel in the edge portion is less than a total amount of droplets per pixel in the non-edge portion.

7. 2. The droplet ejection device according to claim 1, wherein the control unit, in the recording process, ejects droplets from the nozzles so that a total amount of droplets per pixel in the edge portion is greater than a total amount of droplets per pixel in the non-edge portion.

8. the image includes the non-edge portion, the edge portion, and a transition portion between the non-edge portion and the edge portion that has the same density as the edge portion; 2. The droplet ejection device according to claim 1, characterized in that, in the recording process, the control unit ejects droplets from the nozzle so that the amount of each droplet constituting one pixel of the transition portion is less than the amount of each droplet constituting one pixel of the non-edge portion and is greater than the amount of each droplet constituting one pixel of the edge portion.

9. The control unit is The head can be operated in either a first mode or a second mode different from the first mode, when the head is operated in the first mode, in the recording process, droplets are ejected from the nozzles so that the number of droplets per pixel in the edge portion is greater than the number of droplets per pixel in the non-edge portion, and the amount of each droplet constituting one pixel in the edge portion is less than the amount of each droplet constituting one pixel in the non-edge portion; 2. The droplet ejection device according to claim 1, characterized in that, when the head is operated in the second mode, in the recording process, droplets are ejected from the nozzle so that the number of droplets per pixel of the edge portion is the same as the number of droplets per pixel of the non-edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is the same as the amount of droplets per droplet constituting one pixel of the non-edge portion.

10. The control unit is A determination process is performed to determine whether the image shows text; when it is determined in the determination process that the image represents a character, in the recording process, droplets are ejected from the nozzles so that the number of droplets per pixel of the edge portion is greater than the number of droplets per pixel of the non-edge portion and the amount of each droplet constituting one pixel of the edge portion is less than the amount of each droplet constituting one pixel of the non-edge portion; 2. The droplet ejection device according to claim 1, characterized in that, if the judgment process determines that the image does not show characters, in the recording process, droplets are ejected from the nozzle so that the number of droplets per pixel of the edge portion is the same as the number of droplets per pixel of the non-edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is the same as the amount of droplets per droplet constituting one pixel of the non-edge portion.

11. the head includes a first nozzle group including a plurality of the nozzles arranged in a first direction, a second nozzle group including a plurality of the nozzles arranged in the first direction, the nozzles constituting the first nozzle group, and a plurality of the nozzles aligned in a second direction perpendicular to the first direction, a third nozzle group including a plurality of the nozzles arranged in the first direction, the nozzles constituting the second nozzle group, and a plurality of the nozzles aligned in the second direction perpendicular to the first direction, and a fourth nozzle group including a plurality of the nozzles arranged in the first direction, the nozzles constituting the third nozzle group, and a plurality of the nozzles aligned in the second direction perpendicular to the first direction, a moving mechanism for relatively moving the head and the recording medium in the second direction, the nozzles constituting the first nozzle group eject black droplets, the nozzles constituting the second nozzle group eject yellow droplets, the nozzles constituting the third nozzle group eject magenta droplets, and the nozzles constituting the fourth nozzle group eject cyan droplets, The control unit, in the recording process, A droplet constituting one pixel of the non-edge portion is ejected from one nozzle of the first nozzle group; 2. The droplet ejection device according to claim 1, characterized in that droplets constituting one pixel of the edge portion are ejected from one nozzle of the second nozzle group, one nozzle of the third nozzle group that is aligned in the second direction with one nozzle of the second nozzle group, and one nozzle of the fourth nozzle group that is aligned in the second direction with one nozzle of the third nozzle group.

12. The droplet ejection device according to claim 1 , wherein the control unit ejects droplets from the nozzles in such a manner that the number of droplets per pixel in the non-edge portion becomes one in the recording process.

13. The control unit is a data generation process for generating ejection data for ejecting droplets from the nozzles onto a recording medium in the recording process based on the image data, before the recording process; The droplet ejection device according to any one of claims 1 to 12, characterized in that in the data generation process, the ejection data is generated so that the number of droplets per pixel of the edge portion is greater than the number of droplets per pixel of the non-edge portion, and the amount of each droplet constituting one pixel of the edge portion is less than the amount of each droplet constituting one pixel of the non-edge portion.

14. A control device for controlling a droplet ejection device having a head with nozzles, A recording process is executed to record an image on a recording medium by ejecting droplets from the nozzles onto the recording medium based on image data; a control device for ejecting droplets from the nozzle in such a manner that, in the recording process, the number of droplets per pixel in the edge portion of the image related to the image data is greater than the number of droplets per pixel in the non-edge portion, which is a portion other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel in the edge portion is less than the amount of droplets per pixel in the non-edge portion.

15. A method for controlling a droplet ejection device including a head having nozzles, comprising: performing a recording process for recording an image on a recording medium by discharging droplets from the nozzles onto the recording medium based on image data; a control method for controlling the ejection of droplets from the nozzle in the recording process such that the number of droplets per pixel in the edge portion of an image related to the image data is greater than the number of droplets per pixel in a non-edge portion, which is a portion other than the edge portion of the image, and which has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel in the edge portion is less than the amount of droplets per pixel in the non-edge portion.

16. A droplet ejection device including a head having a nozzle, a program for causing the nozzles to eject droplets onto a recording medium based on image data, thereby functioning as a recording unit for recording an image on the recording medium, The recording means ejects droplets from the nozzle so that the number of droplets per pixel in the edge portion of the image related to the image data is greater than the number of droplets per pixel in the non-edge portion, which is a portion other than the edge portion of the image and has the same density as the edge portion, and the amount of droplets per droplet constituting one pixel of the edge portion is less than the amount of droplets per pixel of the non-edge portion.

Images