Inkjet recording device

Abstract

The objective is to minimize the decrease in printing speed and the degradation of image quality even when the power supply drops. [Solution] When the power supply information is at the first level, the dot arrangement is changed to one that increases the dispersion of printed dots compared to the second level, which is higher than the first level.

Description

[Technical Field]

[0001] The present invention relates to a recording device that performs recording using power from a wired connected device and a control method thereof. [Background technology]

[0002] Printing devices that operate solely on power supplied via a USB (Universal Serial Bus) interface (hereinafter referred to as USB bus power) are known.

[0003] Patent Document 1 discloses switching the printing mode depending on whether power is supplied via USB connection or AC power from the main power supply. It also discloses a low-power mode when connected via USB, which limits the number of ink ejection nozzles of the recording device and reduces the operating clock.

[0004] Furthermore, Patent Document 2 discloses that in a recording device equipped with a battery that can connect multiple interfaces, if the battery level is low, the interface connection that consumes the most power among the multiple interfaces is switched to an inactive state.

[0005] Furthermore, Patent Document 3 discloses that when power is supplied to the main unit based on a battery and power from a commercial power source, the voltage drop supplied to the head is obtained based on the circuit impedance and the head current value, and the head is driven based on that data. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-34455 [Patent Document 2] Japanese Patent Publication No. 2003-251893 [Patent Document 3] Japanese Patent Publication No. 2023-45997 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in the technology described in Patent Document 1 above, when power is supplied via USB connection, power consumption is reduced by limiting the number of ejection nozzles driven as a low-power consumption method, which results in a decrease in printing speed.

[0008] Patent Document 2 describes a configuration in which, depending on the battery status, the interface with the highest power consumption among multiple interfaces is disabled. As a result, in information processing equipment that has become common in recent years and only has USB and LAN, only one of them can be used, and communication becomes impossible on the disabled interface.

[0009] Furthermore, in Patent Document 3, the method for determining the power supply status is a switch between battery and commercial power, and it is not possible to control head drive or other functions based on the power supply status via an interface, such as when connected via USB.

[0010] The present invention aims to suppress a decrease in printing speed and a decline in image quality even when the power supply decreases. [Means for solving the problem]

[0011] The present invention provides an inkjet recording apparatus that operates by receiving power from a wired power supply means, comprising: a receiving means for receiving information on the power supply of the wired power supply means; and a dot arrangement control means for changing the arrangement of printed dots according to the power supply information received from the receiving means, wherein the dot arrangement control means changes the dot arrangement to increase the dispersion of printed dots when the power supply information received from the receiving means is at a first level, compared to when the power supply information received from the receiving means is at a second level higher than the first level. [Effects of the Invention]

[0012] According to the present invention, it is an object to suppress a decrease in print quality while suppressing a decrease in print speed even when the supplied power decreases.

Brief Description of the Drawings

[0013] [Figure 1] It is a block diagram of an inkjet recording apparatus according to a first embodiment. [Figure 2] It is an electric unit block diagram according to a first embodiment. [Figure 3] It is a table showing the power supply amount for each connection standard according to a first embodiment. [Figure 4] It is a determination table of a power supply method and dot arrangement according to a first embodiment. [Figure 5] It is a flowchart of control according to a first embodiment. [Figure 6] It is an image processing flow table according to a first embodiment. [Figure 7] It is a determination table of a dot arrangement control method according to a first embodiment. [Figure 8] It is a detailed explanatory diagram 1 of dot arrangement according to a first embodiment. [Figure 9] It is a detailed explanatory diagram 2 of dot arrangement according to a first embodiment. [Figure 10] It is a detailed explanatory table of dot arrangement according to a first embodiment. [Figure 11] It is an explanatory diagram of image characteristics provided for dot arrangement according to a first embodiment. [Figure 12] It is an explanatory diagram of dot arrangements with different dispersions according to a first embodiment. [Figure 13] It is an explanatory diagram of a quantization method according to a second embodiment. [Figure 14] It is a detailed explanatory diagram of a quantization method according to a second embodiment. [Figure 15] It is a detailed explanatory diagram of dot arrangement according to a first embodiment. [Figure 16] It is an explanatory diagram of a Dither matrix according to a first embodiment. [Figure 17]This is an explanatory diagram illustrating the dot arrangement with different dispersions according to the first embodiment. [Figure 18] This is an explanatory diagram of an inkjet recording apparatus according to the first embodiment. [Modes for carrying out the invention]

[0014] The embodiments of the present invention will be described in detail below. Note that the components described in these embodiments are merely illustrative examples of the present invention and do not limit the scope of this invention to them alone.

[0015] (First embodiment) Figure 1 shows an example of the hardware configuration of the recording device 1000 according to this embodiment.

[0016] Figure 1(a) shows an overall perspective view of the recording device. This figure shows the operating parts necessary for operation, including a liquid crystal panel 192 and buttons 191 that the user presses when making a decision. In this embodiment, the device has a liquid crystal panel and physical buttons, but a touch panel may also be used.

[0017] Figure 1(b) is a block diagram showing an example of the hardware configuration of the recording device 1000 according to this embodiment. It comprises a recording device printer 1000, a control unit 100, a printer unit 110, and an operation unit 111. In the control unit 100, the CPU (Central Processing Unit) 101 loads the control program recorded in the ROM (Read Only Memory) 103 into the RAM (Random Access Memory) 102, reads it when necessary, and performs various controls such as power-on control and recording control. The RAM 102 is the main memory of the CPU 101 and is used as a temporary storage area for loading various programs stored in the work area and ROM 103. The ROM 103 stores image data, various programs, and various setting information. In this embodiment, flash storage is assumed as ROM 103, but an auxiliary storage device such as a hard disk may also be used. In this embodiment, the recording device 1000 is assumed to have one CPU 101 using one memory (RAM 102) to execute each process shown in the flowchart described later, but other configurations are also possible. For example, multiple CPUs, multiple RAMs, ROMs, and storage devices can work together to execute each process shown in the flowchart described later. Alternatively, some processes may be executed using hardware circuits. The engine interface (hereinafter referred to as I / F) 104 connects the printer unit 110 and the control unit 100. Image data to be recorded by the printer unit 110 is transferred from the control unit 100 via the engine I / F 104 and recorded on the recording paper in the printer unit 110. The recording device 1000 in this embodiment is an inkjet recording device, and records images by ejecting ink from nozzles provided on the recording head when a head drive unit mounted on the recording head is driven. The operation unit I / F 105 connects the operation unit 111 and the control unit 100. The operation unit 111 is equipped with a liquid crystal display unit with touch panel functionality and operation keys, and functions as a reception unit that receives user instructions. The operation unit 111 is envisioned to include the operation buttons in part 191 of Figure 1(a) and the display LCD in part 192 of Figure 1(a).Network I / F 106 and USB I / F 107 control communication with the host computer PC 112 connected to the recording device 100, respectively.

[0018] Furthermore, USB-TypeC is being proposed as the standard for connecting to modern smart devices, and it is possible to supply power in addition to communication. In this connection, since power supply via USB-TypeC is assumed, a main power supply such as AC connection may not be necessary.

[0019] This embodiment will continue with an explanation based on USB-TypeC. When USB-TypeC is connected, power is also supplied to the recording device 100. The power supply board 108 may also be equipped with a rechargeable battery that can store power. Each part of the control unit 100 is connected to communicate via the bus 109.

[0020] Figure 2 is a block diagram of the power supply system of printer 1000, showing in more detail the configuration of the power supply board section 130 shown in Figure 1(b). Printer 1000 receives power from electric double-layer capacitor (EDLC) 204 V BAT It can be powered by inputting to ChargerIC203, and the power system of the printer's electrical system is controlled by the power system via ChargerIC203. Power is supplied from USB107, which receives connections from an external battery or smart device 120. BUS The current supplied by the ChargerIC203 charges the EDLC204. At the same time, the ChargerIC203 outputs from the EDLC204 to the DC-DC (boost) converter 206.

[0021] The DC-DC (boost) 206 is a boost circuit that increases the voltage from the Charger IC 203. The boosted voltage is used by the MotorDriver 208 to drive the motors of the reading and printing mechanisms, and is also used by the HeadDriver 209 as the power supply for the print head, handling relatively large loads. The boosted power supply is further connected to the DC-DC (buck) 207 circuit to generate the logic power supply voltage used by the ASIC 210, ROM 212, and DDR 211. Here, the ASIC 210 is a custom IC that includes the CPU and peripheral circuits. The Charger IC 203 is an IC that has functions for controlling the input current of the USB 107, controlling the charging of the EDLC 204, and protecting against abnormal operation. The Charger IC 203 communicates with the ASIC 210, which is connected via a Control serial bus. The Charger IC 203 determines the input current according to the external device supplying it.

[0022] In this embodiment, a determination is made in accordance with the USB-BC (USB Battery Charge) standard (hereinafter referred to as BC determination) and the USB-PD (USB Power Delivery) standard (hereinafter referred to as CC determination). Upon receiving the results of the BC determination and CC determination from the ChargerIC203, the ASIC210 determines the threshold values ​​for the charging current, full charge, and over-discharge voltage of the ChargerIC203 and sets the threshold values ​​for the ChargerIC203. The EDLC204 is an electric double-layer capacitor and controls charging from the ChargerIC203 according to the instructions of the ASIC210, and supplies power to the DC-DC (boost) 166, MotorDriver208, and HeadDriver209. BAT Power is supplied by the EDLC204 power supply V BAT The voltage can be transmitted from the ChargerIC203 to the ASIC210. ​​In addition, various information related to power supply can be transmitted from the ChargerIC203 to the ASIC210. ​​This information can be used for various controls of the printing device 101. For example, during the printing operation of the printer 1000, the power supply voltage of the EDLC204 can be transmitted. BATIf the voltage drops, the ASIC210 will stop printing and the EDLC204 power supply voltage will be reduced. BAT The ChargerIC203 is instructed to perform charging control until the voltage reaches a certain threshold. Power supply V BAT Upon receiving notification that the voltage has reached a certain threshold, the ASIC210 can perform a control operation to resume printing.

[0023] Furthermore, the inkjet ejection mechanism ejects small droplets from fine nozzles. When the machine is stopped and not in operation, it is necessary to keep this ejection mechanism moist to prevent the ink inside the nozzles from drying out and causing ejection problems during the next print job. The power supply voltage for driving the mechanism until capping is as described above. BAT If the threshold is exceeded, this power can be used to complete the capping process. If the USB cable is disconnected while the device is operating with power supplied from USB107, or if the power supply is stopped for any reason, the ChargerIC203 notifies the ASIC210, which immediately initiates an action to respond to the power cutoff, i.e., starts capping, and once capping is complete, the entire print job can be terminated.

[0024] An explanatory diagram of this capping is shown in Figure 18. Part 1701 in Figure 18 is the ink droplet ejection mechanism of the inkjet printer, and the CR motor part 1702 operates to eject droplets while moving back and forth on the paper surface part 1703, thereby printing.

[0025] When a print job is completed, or when a certain period of time or a predetermined number of reciprocations has been completed, the ejection mechanism 1701 moves to the capping mechanism 1710, causing the capping mechanism 1710 to rise and cover the ejection mechanism, thereby providing moisture protection to the nozzle. If there are no remaining print jobs, the process ends with the nozzle covered.

[0026] Figures 3(a) and (b) are tables showing the power supply amount for each connection standard. BC1.2 is based on the USB-BC (Battery Charge) standard. As a method for determining a charging USB port (CDP), a method of electrically determining using D+ and D- signal lines for USB data communication is defined. Also, in the case of a standard USB port that is not a charging port, after this detection is completed, communication based on the USB standard is performed, and within that, it is possible to discriminate the USB version. On the other hand, in USB Type-C, the PowerDelivery standard is defined, and the power supply amount can be notified by communication at the CC pin. Note that in the PowerDelivery standard, the supply power voltage can also be controlled from 5V to 48V, but in this figure, the maximum power is described as the value when supplying 5V.

[0027] Figure 3(b) is a decision table for determining the threshold value of V BAT voltage according to the USB power supply amount. The criterion for setting the threshold value of V BAT voltage, for example, threshold value 1 is set as the voltage threshold value at which the capping operation is possible only with the remaining power of the EDLC204 even when the USB power supply stops.

[0028] Figure 4 is a decision table showing the correlation of switching of dot arrangement control, which is characteristic of this embodiment determined by V BAT voltage and the USB power supply amount. In this embodiment, the printing mode uses dot arrangement control 1 when there is sufficient power supply and dot arrangement control 2 that is adapted when the power supply state decreases, and will be described below. The content of the decision table showing the correlation of the USB power supply amount, V BAT voltage, and the printing mode may be held as table data in the program memory, or may be implemented as discrimination code as program code.

[0029] Figure 5 is a flowchart from when the recording device receives power supply by a wired connection and starts printing until the printing operation of the job ends.

[0030] This process begins when the printer 1000 receives power via a wired connection, for example, when a USB cable is inserted. First, the ASIC 210 determines the power supply information of the inserted device. In this embodiment, a USB determination is performed to determine which USB cable is inserted (S501). Based on the determination result, the decision table explained in Figure 3(b) is used to determine V BAT Set the voltage threshold (S502), and ASIC210 will receive a voltage via ChargerIC203. BAT Detect the voltage (S503).

[0031] V detected in S503 in S504 BAT This is a step in which the voltage is compared with threshold 1 shown in Figure 3(b) to determine the branch. In S503, the V detected BAT If the voltage is below the threshold of 1, the process proceeds to S599, notifying the user of insufficient remaining power and the start of charging via the LCD panel 192, and the operation ends.

[0032] V detected in S503 in S504 BAT ga V BAT >When the threshold is 1, ASIC210 uses the USB power supply determination result determined in S501 and the V detected in S502. BAT The dot placement control method is determined by S505 based on the voltage and the decision table explained in Figure 4. In Figure 4, dot placement control 1 is selected when using a USB-TypeC connection with Power Delivery 3.0, dot placement control 2 is selected for Type-C, Power Delivery 2.0 connections, and Type-C standard and BC1.2 CDP connections, dot placement control 3 is selected for USB 3.1, and dot placement control 4 is selected for USB 2.0. A dot placement control with a low power supply may be used when the power supply is high. Details of dot placement controls 1 to 4 will be described later.

[0033] After the dot placement control settings are determined in S505, the printing process starts in S506. Once the predetermined electronic image is printed, the recording device's printing operation ends (S507). In this operation termination step, S507, the ASIC210 performs a capping operation to prevent ink drying in the fine nozzles of the ink ejection mechanism and to avoid ejection failures during the next print. Whether or not the minimum necessary power remains is determined by a Vbat check during the initial operation, so even if the USB-TypeC cable, which also provides power, is unplugged midway through, the capping operation can be completed after the final print pass.

[0034] Figure 6 shows the print control steps and is a flowchart illustrating the configuration of the processing performed by the recording device 1000 in this embodiment. In other words, in this embodiment, the image processing unit is configured by the elements for control and processing of the recording device 1000 shown in Figure 1. However, the embodiment is not limited to this one. For example, the image processing unit may be configured in the host PC 112 shown in Figure 1, or a part of the image processing unit may be configured in the host PC 112 and the other part in the recording device 1000.

[0035] Input processor 601 outputs image data received from host PC 112 to image processor 602.

[0036] The image processing unit 602 comprises an input color conversion process 603, an ink color conversion process 604, a quantization process 605, a dot pattern unfolding process 606, and a path decomposition process 607.

[0037] The input color conversion process 603 converts the input image data received from the input process 601 into image data corresponding to the color reproduction range of the recording device. The input image data is data representing color coordinates (R, G, B) in a color space such as sRGB, which is the color representation of the monitor. The input color conversion process 603 converts the input image data of each 8 bits R, G, B into image data corresponding to the color reproduction range of the recording device (R', G', B') using known methods such as matrix operations and processing using a three-dimensional LUT. In this embodiment, a three-dimensional lookup table is used, and interpolation is used in combination with it to perform the conversion process. The resolution of the 8-bit image data handled in image processing 602 is described as 600 dpi.

[0038] The ink color conversion process 604 converts the 8-bit R, G, and B image data processed by the input color conversion process 603 into image data using ink color signal value data for use in the recording device.

[0039] The quantization process 605 performs quantization on the 10-bit color signal value data of each ink color output from the ink color conversion process 604 to reduce the number of gradations. The quantization processes used in inkjet printers mainly use error diffusion (ED) and dithering using a threshold matrix. In this embodiment, the explanation will be given using dithering, but other quantization methods may also be used. Figure 16 shows an example of a threshold matrix used for dithering. Both threshold matrices have blue noise characteristics, but the threshold distributions are different from each other. This is not the only example. Two matrix examples are shown in this figure. The matrix in this figure is applied to each color. For example, the first matrix can be applied to C ink and the second matrix to M ink. This is not the only example of a matrix and the colors to which it is applied.

[0040] In the dot pattern unfolding process 606, the result of the quantization process 605 is unfolded into a printed dot pattern. Details will be described later using Figure 12.

[0041] The path decomposition process 607 divides the image data, which consists of 10-bit color signal values ​​for each ink color processed by the quantization process 605, into scan-specific data for recording over multiple scans.

[0042] The output process 608 drives the recording head based on the data divided for each scan by the path decomposition process 607, and ejects ink of each color onto the recording medium to perform recording.

[0043] Next, the details of the dot placement control method will be explained using Figures 8 to 10.

[0044] Figure 8 shows the detailed control contents of dot placement control methods 1 to 4, which are referenced in relation to the power supply amount, for the determination method of dot placement control setting S505 shown in Figure 6.

[0045] Figure 8 shows the setting conditions for the combination of ink color conversion processing S604 and quantization processing S605 in the actual image processing unit S602. Here, "thinning amount (%)" indicates the limiting amount of ink coating, i.e., the total amount of ink droplets ejected from the inkjet head. In this figure, the thinning amount for both C ink and M ink is 25%, resulting in the dot arrangement for solid printing of "dot arrangement control 4" in Figure 7. Similarly, Figure 9 shows the dot arrangement for solid printing of "dot arrangement control 2" in Figure 7, with the thinning amount for both C ink and M ink being 50%. In this embodiment, according to the tables in Figures 4 and 7, when the power supply is Type-C Power Delivery 3.0, the power supply is 3.0A (second level), and the normal (low dispersion) dot arrangement control of dot arrangement control 1 is performed. When the power supply is lower than that, for example, power supply BC1.2 USB2.0 (first level), the highly dispersion dot arrangement control of dot arrangement control 4 is performed.

[0046] In the ink color conversion process S604, the ink color conversion process is performed based on the "decimation amount (%)" corresponding to the supplied power. It is suitable to perform the calculation of the decimation amount in S604, where the values ​​for each ink color are determined. In addition, the dot sizes may differ. In that case, since the power required for dot ejection differs for each ink color, the decimation amount for each ink color should be determined taking these differences into consideration. Although Figure 7 shows a uniform value, the decimation amount can be changed for each ink color, as long as the total power falls within the predetermined range. Furthermore, to simplify the process, it is also possible to achieve this by brightening the input image density in the input color conversion process S603 of the preceding process.

[0047] "Declined Printing Amount (%)" is a relative value of the amount of print ink after decimation, with the maximum power supply being 100%. This indicates that, with the maximum power supply being 100%, the dot placement control 1 to 4 gradually reduces the amount of ink printed as the power supply decreases. By gradually reducing the printing amount in accordance with the power supply in this way, it is possible to prevent a decrease in speed.

[0048] Furthermore, in the same diagram, the Dither setting for quantization process S605 is controlled based on the difference in the dispersion of the printed dots. Normal processing with "low dispersion" is performed only when the power supply is at its maximum. When the power supply decreases, it is set to perform processing with "high dispersion".

[0049] The "dispersion of dot arrangement" in this embodiment will be explained using Figures 12(a) and 12(b).

[0050] Figure 12(a) shows the dot arrangement after quantization processing 605 in a 2x2 pixel at 600 dpi. The number of printed dots for each pixel of cyan ink (C ink) is shown as 1201 and 1204, and the number of printed dots for each pixel of magenta ink (M ink) is shown as 1202 and 1203, with the sum being 1203 and 1206. In this figure, the numerical value for each pixel indicates the number of printed dots on the paper, where "0" indicates a pixel with "0" printed dots, "1" indicates a pixel with "1" printed dot, and "2" indicates a pixel with "2" printed dots. Dot arrangements with "low dispersion" are 1201, 1202, and 1203, while dot arrangements with "high dispersion" are 1204, 1205, and 1206. In this figure, the case where one dot each of C ink and M ink is printed on a 2x2 pixel is shown.

[0051] Figure 12(b) shows the actual state of printed dots on paper using C ink and M ink. In reality, the printed dots are close to circular, and due to dot gain, their area is larger than that of actual 600 dpi pixels.

[0052] Furthermore, Figure 12(c) shows the total number of pixels for each number of printed dots in dot arrangements 1201 to 1206.

[0053] In Figure 12(a), in the single-color dot arrangement for each color, there is one pixel with "1 dot" and the remaining three pixels are pixels without printed dots. In the sum of C ink + M ink, there is a difference in the number of "0 dots", "1 dot", and "2 dots" between 1203 and 1206.

[0054] Figure 12(c) shows the difference in the number of occurrences. In 1203, there is one pixel with a sum of "2 dots," whereas in 1206 there are no pixels with a sum of "2 dots." Conversely, 1206 has two pixels with a sum of "1 dot," while 1203 has none. As a result, there are three pixels with "0 dots" in 1203, compared to only two pixels in 1206. In this embodiment, this difference in the degree to which pixels with overlapping C ink and M ink occur is called the "difference in dispersion." Furthermore, a dot arrangement in which the degree to which pixels with overlapping inks of both inks occur is relatively low is called a "dot arrangement with high dispersion," and a dot arrangement in which the degree to which pixels with overlapping inks of both inks occur is relatively high is called a "dot arrangement with low dispersion."

[0055] Furthermore, as can be seen from the print dot arrangement in Figure 12(b), in a 600dpi 2x2 pixel area, the area of ​​unprinted paper (white background) is larger for 1204 and smaller for 1208. Even when printing with the same number of dots of C ink and M ink, 1208 has a higher coverage rate on the paper surface, resulting in better color development efficiency and higher optical density even when the same amount of colorant is applied to the paper surface.

[0056] Furthermore, while this embodiment specifies the dot placement conditions for C ink and M ink, the ink colors are not limited to these. The same applies to other ink colors, as well as to inks of the same color.

[0057] Next, the method for controlling the dispersion of dot placement in this control system will be explained using Figures 8 to 11.

[0058] Figures 8 and 9 show the number of dots per pixel for cyan ink (C ink) after quantization processing 605 as 801, 804, 901, and 904, and the number of dots per pixel for magenta ink (M ink) as 802, 805, 902, and 905, and the total number of dots per pixel for cyan and magenta ink as 803, 806, 903, and 906. For the sake of simplicity, the size is schematically set to 8 pixels × 8 pixels, and the Dither matrix differs from that of Figure 16 mentioned above, but this does not affect the intent of this embodiment. In addition, although the dot arrangement conditions for C ink and M ink are defined in this embodiment, the ink colors are not limited to these.

[0059] Figure 8 shows the case where the recording duty cycle for each color of C ink and M ink is 25%, and Figure 9 shows the case where the recording duty cycle for each color is 50%.

[0060] In both figures, the numerical value for each pixel indicates the number of dots printed on the paper. "0" indicates a pixel with "0 dots," "1" indicates a pixel with "1 dot," and "2" indicates a pixel with "2 dots." Dot arrangements with low dispersion are 801, 802, 803 in Figure 8 and 901, 902, 903 in Figure 9. Dot arrangements with high dispersion are 804, 805, 806 in Figure 8 and 904, 905, 906 in Figure 9.

[0061] Figures 10(a) and 10(b) show the total number of pixels for each 8x8 pixel area under the conditions of Figure 8 and Figure 9, respectively. Figure 10(a) is for 25% duty cycle printing as in Figure 8, and Figure 10(b) is for 50% duty cycle printing as in Figure 9.

[0062] The following describes the characteristics using the dot arrangement when printing with a 25% duty cycle.

[0063] As shown in Figure 8, regardless of the difference in dispersion, in the single-color dot arrangement for each color, there are 16 pixels (= 8 pixels × 8 pixels × 25%) that are "1 dot" pixels, and the remaining 48 pixels are pixels without printed dots. On the other hand, due to the difference in dispersion, there is a difference in the number of "0 dots," "1 dots," and "2 dots" between the total of C ink + M ink 803 and 806.

[0064] Figure 10(a) illustrates this difference, showing that in a dot arrangement with low dispersion, there are fewer pixels with "2 dots" printed and consequently more pixels with "1 dot" printed. In this embodiment, this difference in the degree to which pixels with C ink and M ink overlap occur is called the "difference in dispersion." Furthermore, a dot arrangement in which the degree to which pixels with both inks overlap is relatively low is called a "dot arrangement with high dispersion," and a dot arrangement in which the degree to which pixels with both inks overlap is relatively high is called a "dot arrangement with low dispersion."

[0065] When printing at 25% duty cycle, the pixels where C ink and M ink overlap are not arranged in a highly dispersed dot pattern at all; rather, C ink and M ink are arranged in completely separate pixels.

[0066] Similarly, in Figure 9 at 50% duty cycle, the single-color dot arrangement for each color has 32 pixels (= 8 pixels × 8 pixels × 25%) with "1 dot" and the remaining 32 pixels with no printed dots. On the other hand, due to the difference in dispersion, there is a difference in the number of "0 dots," "1 dots," and "2 dots" between the total C ink + M ink of 803 and 806. In Figure 10(b), similar to the 25% duty cycle case, the dot arrangement with higher dispersion has a "lower" number of pixels with "2 dots" printed and a "higher" number of pixels with "1 dot" printed. The difference from the 25% duty cycle case is that even with the highly dispersed dot arrangement, 10 pixels with "2 dots" printed occur. This is because as the duty cycle increases, the number of pixels in the printed dots increases and they become denser. However, a dot arrangement where the number of pixels for "2-dot" printing, where C ink and M ink overlap, is relatively high is called a "low-dispersion dot arrangement," and a dot arrangement where the number of pixels is high is called a "high-dispersion dot arrangement."

[0067] Figure 17 shows the dither matrix used to realize the dot arrangements in Figures 8 and 9. Using this matrix, quantization processing is performed in S605 to realize the dot arrangements with different dispersions mentioned above.

[0068] By utilizing differences in the dispersion of dot arrangements, it is possible to improve image density and color reproduction. This will be explained using Figure 11. In Figure 11, the horizontal axis is the recording duty cycle, and the vertical axis is the saturation (C*). C* is defined by the CIE and is one of the indicators of "vividness" that shows the color reproduction quality of an image. A higher value indicates a more "vivid" appearance. In the figure, the solid line 1101 shows the relationship between the printing duty cycle and C* when the dot arrangement has low dispersion, and the dashed line 1102 shows the relationship between the printing duty cycle and C* when the dot arrangement has high dispersion. From low to intermediate duty cycles, 1102 tends to have a higher C*. As the duty cycle increases, the difference disappears, and at high duty cycles, they are almost the same. This is because, as the duty cycle increases, there are more instances of arrangements where C ink and M ink overlap, as shown in Figure 12(a) 1203, and arrangements where C ink and M ink are printed on different pixels, as shown in 1206. As mentioned earlier, the dot arrangement 1208 allows for a relatively higher paper surface coverage than the dot arrangement 1204, and there are more dot arrangements with good color development efficiency as the duty cycle increases. In particular, when performing decimal printing with a lower-than-normal power supply, as in this embodiment, image formation is performed using an intermediate duty cycle rather than a high duty cycle, and such "highly dispersed dot arrangements" are more advantageous for the overall color development of the image.

[0069] Next, the effects of controlling the printing method in this embodiment will be described.

[0070] As shown in Figure 7, by gradually reducing the amount of printing by thinning out the dots according to the power supply, it is possible to prevent a decrease in speed. Furthermore, by using a highly dispersed dot arrangement, it is possible to suppress the decrease in density and color development caused by thinned printing. In this embodiment, the control of the dot arrangement of C ink and M ink was explained, but it is not limited to this as long as the characteristics shown in Figure 11 can be reproduced. In Figure 11, the example of saturation C* is used for explanation, but similarly, even if the image density is shown using OD values, a highly dispersed dot arrangement will result in a relatively higher density and a more desirable image. Also, even in the case of a single color rather than multiple colors, if a highly dispersed dot arrangement as shown in Figure 12 can be realized, the intended effects of this embodiment can be expected to be similarly achieved.

[0071] Furthermore, when the power supply is high and the power supply during printing is sufficient, the dot arrangement is generally determined by considering the image effects due to variations in ink dot placement on the paper surface. In this embodiment, however, if the dot dispersion is relatively high when the power supply is reduced, it is possible to suppress the decrease in density and color development due to thinning printing.

[0072] In this embodiment, as described above, the arrangement of recording dots is controlled according to the supplied power, but the actual printed image on the paper differs for each control. By providing a means to notify the user of the printing status, it is expected that user convenience will be enhanced by informing the user at the time of printing that the output result will be different from the normal state. For example, the display LCD 192 can be used to notify the user in advance that the dot arrangement status will change. If the user knows in advance that the print job is different from the normal state, the user who wants to change it back to the normal state can change the power supply method and print. In addition, by showing the user the current power supply method at that time, the user will be able to clearly understand the current power supply status and reduce the effort required for confirmation. The content of the notification to the user here will be the name of the current power supply standard (see Figure 4) and, correspondingly, whether the printing status is normal or not. The display wording is not limited to this, as long as the user can understand the change in dot arrangement status and the power supply method (power supply status). Furthermore, the means of notifying the user does not have to be a means like the display LCD 192, and a simple configuration using LEDs would also be acceptable. In this case, the display of the printer status changes on the LCD192 is discontinued, and the changes are indicated by the number of LEDs and their blinking intervals, etc. This reduces the power required for the LCD192, and is expected to allow that power to be allocated to the printing operation.

[0073] (Second Embodiment) Next, a second embodiment will be described using Figures 13 and 14. In the first embodiment, a "highly dispersed dot arrangement" was achieved by switching the Dither pattern when the power supply was low, but a form in which a similar dot arrangement is achieved by another method will be described. Figure 13 shows the details of the quantization process S605 in Figure 6 in this embodiment. Figure 13(a) is a block diagram showing the quantization process including preprocessing, and the processing steps are shown in Figure 13(b).

[0074] In the figure, the data to be processed is shown as In1(x,y), and the reference data is shown as In2(x,y) and In3(x,y). Here, (x,y) represents the pixel position and is a coordinate parameter for the threshold acquisition unit 305 to select a threshold corresponding to the pixel position of the data to be processed from the threshold matrix.

[0075] The data converted into individual ink signal values ​​by S1304 is set to In1(x,y), In2(x,y), and In3(x,y). The colors for which you want to increase dispersion are set to In2(x,y) and In3(x,y), and the other colors are set to In1(x,y). Following the first embodiment, In2(x,y) and In3(x,y) will be set to the data for C ink and M ink, respectively. In1(x,y) is shown as data for one color for convenience, but it can contain data for multiple colors. Also, if the power supply is high and a highly dispersed dot arrangement is not required, each color can be input to In1(x,y) and processed independently.

[0076] The reference data In2(x,y) and In3(x,y) input to the color processing unit 304 are first input to the threshold offset amount calculation unit 308 (step S1301). Then, the threshold offset amount calculation unit 308 uses these reference data to calculate the threshold offset Ofs_1(x,y) for the data to be processed In1(x,y) (step S1302). In this embodiment, the threshold offset value Ofs_1(x,y) is calculated by (Equation 1). Ofs_1(x,y) = Σi[Ini(x,y)] ···(Equation 1)

[0077] Here, i is a parameter that individually indicates the reference data (hereinafter referred to as actual reference data) used to determine the threshold for the data to be processed In1 from among the reference data In2(x,y) and In3(x,y). The number and type of such actual reference data are predetermined for each data to be processed.

[0078] In this example, when the data to be processed is In1(x,y), the actual reference data is set to none (null), and when the data to be processed is In2(x,y), the actual reference data is set to In1(x,y). Also, when the data to be processed is In3(x,y), the actual reference data are set to In1(x,y) and In2(x,y). Therefore, the offsets Ofs_1(x,y) to Ofs_3(x,y) for each of the data to be processed, In1(x,y) to In3(x,y), can be expressed as follows from (Equation 1). Ofs_1(x,y) = Σi[In(x,y)] =0 (Equation 1-1) Ofs_2(x,y) = Σi[In(x,y)] =In1(x,y) (Equation 1-2) Ofs_3(x,y) = Σi[In(x,y)] =In1(x,y)+In2(x,y) (Equation 1-3)

[0079] Once the threshold offset values ​​Ofs_1(x,y) to Ofs_3(x,y) are calculated in this way, they are input to the threshold offset amount addition unit 1309. The threshold offset amount addition unit 1309 obtains the threshold Dth corresponding to the coordinates (x,y) of the data to be processed In(x,y) from the threshold acquisition unit 1305 (step S1303).

[0080] In step S1304, the threshold offset amount addition unit 1309 subtracts the threshold offset value Ofs_1(x,y) input from the threshold offset amount calculation unit 1308 from the threshold Dth(x,y) input from the threshold acquisition unit 1305 to obtain the quantization threshold Dth'(x,y). Dth´(x,y)=Dth(x,y)-Ofs_1(x,y) ···(Formula 2)

[0081] In this case, if Dth'(x,y) is a negative value, Dth_max (the maximum value of the thresholds that the dither pattern has) is added to obtain the quantization threshold Dth'(x,y). As a result, the quantization threshold Dth' is always between Dth'=0 and Dth_max. In other words, When Dth'(x,y)<0 Dth´(x,y)=Dth´(x,y)+Dth_max ···(Formula 3) Let's assume that.

[0082] Once the quantization threshold Dth'(x,y) is obtained by (Equation 2) or (Equation 3), the quantization processing unit 1306 compares the data to be processed In1(x,y) with the quantization threshold Dth'(x,y) and determines whether to record (1) or not record (0) the dot for the pixel position (x,y). This completes the process.

[0083] Figure 14 shows the range of thresholds (0 to Dth_max) arranged in the threshold matrix that are judged as recording (1) when multi-level data (In1 to In3) for each of the first to third colors are input. The horizontal axis represents the thresholds Dth0 to 4094, and 1710 is Dth_max (the maximum value of the thresholds of the dither pattern). Each line indicates the threshold range in which a dot is placed. In this example, for the first color, Ofs_1 = 0 from (Equation 1-1). Therefore, the pixel positions corresponding to the thresholds 0 to In1 (1702 to 1703) among 0 to Dth_max are set as recording (1).

[0084] For the second color, Ofs_2 = In1 from (Equation 1-2). Therefore, when quantized with the threshold Dth' obtained according to (Equation 2) and (Equation 3), the thresholds In1 to In1 + In2 (1705 to 1706) from the thresholds 0 to Dth_max arranged in dither pattern 310 are set to record (1).

[0085] For the third color, from (Equation 1-3), Ofs_3 = In1 + In2. Therefore, when quantized with the threshold Dth' obtained according to (Equation 2) and (Equation 3), among the thresholds 0 to Dth_max arranged in the threshold matrix, In1 + In2 to In1 + In2 + In3 (1708 to 1709) will be set as record (1). However, in this example, we assume that In1 + In2 + In3 exceeds Dth_max. In this case, for the region exceeding Dth_max, the threshold corresponding to the remainder when (In1 + In2 + In3) is divided by Dth_max, i.e., 0 to In1 + In2 + In3 - Dth_max, will be set as record (1). That is, the range of thresholds determined to be record (1) is In1 + In2 to Dth_max (1708 to 1710) and 0 to In1 + In2 + In3 - Dth_max (1707 to 1711).

[0086] Thus, in general color processing, while a common threshold matrix is ​​used, a unique quantization threshold Dth' is obtained for each color by offsetting the input values ​​of each color. Then, this newly obtained quantization threshold Dth' is used in the quantization process. This makes it possible to place C ink and M ink on different pixels, and as a result, a highly dispersed dot arrangement that exhibits the effect of this embodiment can be realized. In this way, by using this method, it is possible to achieve dot arrangements with different dispersions using a method other than switching the Dither matrix as in the first embodiment.

[0087] As described above, similar to the first embodiment, by gradually reducing the amount of printing in accordance with the power supply, it is possible to prevent a decrease in speed and suppress a decrease in density and color development due to thinning printing by using a dot arrangement with high dispersion.

[0088] In Figures 13 and 14 above, a quantization method using a Dither matrix is ​​employed to realize dot arrangements with different dispersion properties. This method is similar to known methods for controlling granularity in Dither. Quantization methods for controlling granularity have been disclosed not only in Dither but also in error diffusion methods. It goes without saying that by using these known quantization methods in the embodiments of this embodiment, it is possible to realize dot arrangements with different dispersion properties, similar to those in this embodiment.

[0089] Furthermore, while the first and second embodiments described the control of dot dispersion using two colors, C ink and M ink, the invention is not limited to this. The control of dot dispersion can be performed using three inks spaced apart, or multiple sets of two colors can be used, with dot dispersion control performed between colors in the same set. For example, the first ink set could be C ink and M ink, and the second ink set could be Y ink and K ink. Moreover, different quantization methods may be used for the first and second ink sets. For example, the first ink set could be controlled by the Dither pattern of the first embodiment, and the second ink set could be controlled by the Dither method described in the second embodiment, or a combination of error diffusion and the Dither method could be used. The intention of this embodiment is that different dot dispersions can be achieved by these combinations. As a result, by gradually reducing the amount of printing according to the power supply, it is possible to prevent a decrease in speed while achieving a highly dispersed dot arrangement, thereby suppressing the decrease in density and color development caused by thinning printing.

[0090] (Third embodiment) Next, a third embodiment will be described. In this embodiment, multi-level quantization is performed in the quantization process S605 in Figure 6, and the printed dot pattern is determined according to the multi-level in the dot pattern unfolding process S606. Such multi-level quantization is often used when the droplets of the printed dots are small and it is possible to form a high-resolution image relative to the quantization resolution.

[0091] Figure 15 shows the dot unfolding method of this embodiment. Figure 15 shows the dot arrangement for each output level of the quantization process S605. The quantization resolution is 600 dpi and the output value is 5 levels, and the configuration allows dot arrangement in units of 1200 dpi. Similar to the explanation of dot arrangement in the first embodiment, the dot arrangements for C ink only, M ink only, and C + M ink are shown, and the numerical value of each pixel also indicates the number of printed dots. The dispersion does not change for the dot arrangement of each single ink color. In the dot arrangement of C ink + M ink, it can be seen that the number of pixels with 2 printed dots differs from the dot arrangement with high dispersion, especially at quantization levels 2 and 3, and that inks with low dispersion appear more frequently.

[0092] In the dot pattern unfolding process S606, the dot pattern is switched for the same quantization level according to the supplied power, thereby enabling control of dispersion as in the first and second embodiments. Similar to the first and second embodiments, by gradually reducing the amount of printing according to the supplied power, it is possible to prevent a decrease in speed while suppressing a decrease in density and color development due to thinning printing by using a highly dispersed dot arrangement.

[0093] By combining the dot dispersion control method with different dot dispersion characteristics achievable in this embodiment with the dot dispersion control methods in the first and second embodiments, although the dispersion was in two stages in Figure 7, finer control becomes possible. As a result, it becomes possible to more optimally suppress density reduction and color degradation due to thinning printing according to the supplied power.

Claims

1. An inkjet recording device that operates by receiving power from a wired power supply means, A receiving means for receiving information on the power supply of the wired power supply means, The system includes a dot arrangement control means that changes the arrangement of printed dots according to the power supply information received from the receiving means, The dot arrangement control means is characterized in that, when the power supply information received from the receiving means is at a first level, the dot arrangement is changed to one that increases the dispersion of printed dots compared to when the power supply information received from the receiving means is at a second level higher than the first level.

2. The inkjet recording apparatus according to claim 1, characterized in that the process of changing the arrangement of printed dots performed by the dot arrangement control means includes at least one of either a quantization process or a dot pattern unfolding process.

3. The inkjet recording apparatus according to claim 2, characterized in that the quantization process in the dot arrangement control means includes at least one of the Dither method or the error diffusion method.

4. The inkjet recording apparatus according to claim 1, characterized in that the dot arrangement control means changes the arrangement of printed dots for at least two ink colors.

5. The inkjet recording apparatus according to claim 1, characterized in that the dot arrangement control means lowers the recording duty cycle on the paper when the power supply information received from the receiving means is at the first level compared to when the power supply information received from the receiving means is at the second level.

6. The inkjet recording apparatus according to claim 1, characterized in that the receiving means receives at least two stages of power supply information.

7. The inkjet recording apparatus according to claim 1, characterized in that the wired connection is a USB connection.

8. Having a means of display, The inkjet recording apparatus according to claim 1, characterized in that the display means indicates the state of change in the arrangement of printed dots.

9. The inkjet recording apparatus according to claim 8, characterized in that the display means indicates power supply information.

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