Inkjet recording device, print control device, and print control method

Abstract

The objective is to enable printing settings that are independent of ink density. [Solution] In the inkjet printer 100A, the control unit 200A determines the ink concentration based on the ambient temperature measured by the temperature measuring unit 275 and the ink viscosity measured by the ink viscosity measuring unit 274 using the ink concentration determination unit 1001A, and the ink particle temperature control unit 1002A controls the temperature set value of the ejected ink to the heating heater 276 based on that ink concentration.

Description

[Technical Field]

[0001] The present invention relates to, for example, an inkjet recording apparatus, a print control apparatus, and a print control method. [Background Art]

[0002] Among inkjet printers, charge-controlled inkjet printers are mainly used as industrial printers for applications such as printing serial numbers, expiration dates and the like on products that are moving along a production line.

[0003] This charge-controlled inkjet printer is configured to pressurize liquid ink filled in an ink tank with a pump and supply the pressurized ink to nozzles of a print head.

[0004] Therefore, for example, Patent Document 1 discloses a configuration that controls ink temperature so that the temperature of ink ejected from nozzles becomes a predetermined temperature suitable for a set print setting. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-91174 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] When the temperature of ink is lower than the temperature suitable for a predetermined print setting, the ink viscosity becomes higher than the ink viscosity suitable for the predetermined print setting. By using the technology of Patent Document 1 mentioned above, the temperature of ink ejected from nozzles is heated to a predetermined temperature, thereby adjusting the ink viscosity to one suitable for the predetermined print setting. Accordingly, high-precision printing that enables ink ejection to a target position can be realized.

[0007] However, in order to achieve high-precision printing with predetermined printing settings, it is desirable that the ink density also be suitable for those settings. Ink density can change, for example, due to solvent entering the ink tank. Therefore, in conventional technologies such as the one described in Patent Document 1 above, even if the ink temperature is set appropriately, changes in ink density are not taken into account, making it difficult to achieve clean printing.

[0008] The object of the present invention is to provide an inkjet recording device, a print control device, and a print control method that reduce the decrease in print quality caused by fluctuations in ink density. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the above objectives, one embodiment of the present invention is an inkjet recording apparatus having a temperature measuring unit for measuring ambient temperature and an ink viscosity measuring unit for measuring ink viscosity, and ejecting ink to perform a printing process, characterized in that it comprises a control unit that determines the ink concentration based on the ambient temperature measured by the temperature measuring unit and the ink viscosity measured by the ink viscosity measuring unit, controls the temperature set value of the ejected ink based on the determined ink concentration to control the printing process, and a print head that prints on the object to be printed based on the control of the control unit.

[0010] Another embodiment of the present invention is an inkjet recording apparatus having a speed sensor for detecting the ink ejection speed and ejecting ink to perform a printing process, characterized in that it comprises a control unit that controls a temperature set value of the ejected ink based on the ejection speed measured by the speed sensor, and a print head that prints on a workpiece based on the control of the control unit.

[0011] Another embodiment of the present invention is a printing control device that has a temperature measuring unit for measuring ambient temperature and an ink viscosity measuring unit for measuring ink viscosity, and performs a printing process by ejecting ink, characterized in that it comprises a determination unit for determining the ink concentration based on the ambient temperature measured by the temperature measuring unit and the ink viscosity measured by the ink viscosity measuring unit, and a control unit for controlling the temperature set value of the ejected ink based on the ink concentration determined by the determination unit.

[0012] Another embodiment of the present invention is a print control device that has a speed sensor for detecting the ink ejection speed and ejects ink to perform a printing process, and is characterized by comprising a control unit that controls the temperature set value of the ejected ink based on the ejection speed measured by the speed sensor.

[0013] Another embodiment of the present invention is a printing control method for a system that ejects ink to perform a printing process, wherein the system has a speed sensor and a heating heater, and is characterized in that it determines an ink temperature setpoint based on the ink ejection speed detected by the speed sensor, and controls the ink temperature in the heating heater based on that temperature setpoint. [Effects of the Invention]

[0014] According to the present invention, it is possible to reduce the decrease in print quality caused by fluctuations in ink density. Problems, configurations, and effects other than those described above will be clarified by the following description of this embodiment. [Brief explanation of the drawing]

[0015] [Figure 1] This is a configuration diagram showing the external appearance of an inkjet printer in Embodiment 1 of the present invention. [Figure 2] This is a diagram showing the internal configuration of an inkjet printer in Embodiment 1 of the present invention. [Figure 3] This is a block diagram showing the functions of an inkjet printer in Embodiment 1 of the present invention. [Figure 4]It is a flowchart illustrating the operation in Embodiment 1 of the present invention. [Figure 5] It is an explanatory diagram illustrating the temperature dependence of ink viscosity in Embodiment 1 of the present invention. [Figure 6] It is an explanatory diagram illustrating the method for determining the set value of heating temperature in Embodiment 1 of the present invention. [Figure 7] It is an explanatory diagram illustrating the temperature dependence of ink viscosity in Embodiment 1 of the present invention. [Figure 8] It is a diagram showing the method for determining the set value of heating temperature in Embodiment 1 of the present invention. [Figure 9] It is a configuration diagram showing the internal configuration of an inkjet printer in Embodiment 2 of the present invention. [Figure 10] It is a block diagram showing the functions of an inkjet printer in Embodiment 2 of the present invention. [Figure 11] It is a flowchart illustrating the operation in Embodiment 2 of the present invention. [Figure 12] It is an explanatory diagram illustrating the temperature dependence of the ejection speed of ink particles in Embodiment 2 of the present invention. [Figure 13] It is an explanatory diagram illustrating the method for determining the set value of heating temperature in Embodiment 2 of the present invention. [Figure 14] It is an explanatory diagram illustrating the temperature dependence of the ejection speed of ink particles in Embodiment 2 of the present invention. [Figure 15] It is an explanatory diagram illustrating the method for determining the set value of heating temperature in Embodiment 2 of the present invention. [Figure 16] It is a block diagram showing the functions of an inkjet printer in Embodiment 3 of the present invention. [Figure 17] It is a flowchart illustrating the operation in Embodiment 3 of the present invention. [Figure 18] It is a configuration diagram showing a printing system according to Embodiment 4 of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0016] The present invention will now be described in detail with reference to specific embodiments. The object of this embodiment is to provide a highly robust inkjet printer that adjusts the heating setting value using ink density as a feedback value in order to reduce the deterioration of print quality due to fluctuations in ink density.

[0017] It should be noted that the present invention is not limited to the embodiments described below, and it will be easily understood by those skilled in the art that its configuration can be modified without departing from the technical idea or spirit of the invention. In addition, in the configuration of the embodiments described below, the same reference numerals are used for parts that are the same device or have similar operation or function, and redundant explanations may be omitted. Furthermore, the positions, sizes, shapes, and ranges of each component shown in the drawings are simplified for the purpose of facilitating understanding of the present invention, and do not represent the actual positions, sizes, shapes, and ranges of each component.

[0018] [Embodiment 1] Embodiment 1 of the present invention describes a method for determining the ink concentration by measuring the ambient temperature and ink viscosity, and adjusting the heating setting value using the ink concentration as a feedback value.

[0019] The printing device in this embodiment 1 will be described in detail with reference to Figures 1 to 8. An inkjet printer, which is a charge-controlled inkjet recording device, will be used as an example of the printing device.

[0020] First, let's briefly explain inkjet printers. In a nozzle, supplied ink is continuously ejected as an ink column. However, by applying an excitation voltage to a piezoelectric element or similar device adjacent to the nozzle during ejection, a periodic perturbation is imparted to the ink. This perturbed ink column is then broken, forming continuously (periodically) generated ink particles that fly at high speed. The magnitude of the perturbation can be adjusted by the excitation voltage.

[0021] By placing a charging electrode at or near the cut point in the ink where these ink particles are formed, and generating an electric field around this charging electrode, each ink particle in high-speed flight can be charged.

[0022] At the charging electrode, an electric field corresponding to the printed content is applied, thereby imparting the necessary amount of charge to each ink particle according to the printed content. Downstream from the charging electrode, a deflection electrode consisting of two electrodes to which a constant voltage is applied is positioned. As each charged ink particle flies through the deflection electrode, its flight direction is deflected according to the amount of charge it has been imparted.

[0023] The system then uses a transport device to attach these deflected ink particles to the object being printed on while it is in motion, thereby printing the image onto the object using the ink particles.

[0024] Furthermore, ink particles that are not charged within the charging electrode travel in a straight line through the deflection electrode, are captured by the gutter, and are collected in the ink container as recovered ink, which is then reused for discharge from the nozzle. During this process, organic solvent components in the ink volatilize, so the volatilized ink solvent components (supplementing solution) are replenished into the ink as needed to maintain an appropriate ink concentration.

[0025] In such inkjet printers, it is necessary to maintain the "cutting position"—the point at which the ink column ejected from the nozzle is cut and becomes an ink particle (the distance from the nozzle tip to the point where the ink particle is formed)—at an appropriate location. If this position is not maintained, the flying ink particles cannot be properly charged at the charging electrode, making it impossible to achieve high-quality printing. Therefore, it is important to appropriately control this cutting position so that it falls within a predetermined range.

[0026] The cutting position can be adjusted by the pump pressure used to eject ink from the nozzle and the excitation voltage applied to a piezoelectric element installed adjacent to the nozzle. More specifically, the cutting position is adjusted by applying the excitation voltage to the nozzle, or more precisely, to the piezoelectric element installed adjacent to the nozzle.

[0027] By the way, printing environments and materials vary widely, and there are multiple types of inks that can be used with inkjet printers.

[0028] Furthermore, appropriate printing conditions vary depending on various factors, including the type of ink, the nozzle, and the temperature environment which affects the surrounding ink temperature. Printing conditions include the values ​​of excitation voltage, excitation frequency, pump pressure, charging voltage, and deflection voltage.

[0029] For each type of ink and ink temperature, it is difficult to achieve high-precision printing unless the printing settings, such as the pump pressure for ink ejection and the applied excitation voltage, are appropriately configured. Therefore, when printing, it is necessary to set the pump pressure and excitation voltage conditions appropriately before printing. (Overall configuration of an inkjet printer) First, we will explain the configuration using Figures 1 to 3.

[0030] As shown in Figure 1, the inkjet printer 100A of this embodiment 1 comprises a main unit 1 and a print head 2.

[0031] The main unit 1 and the print head 2 are connected by a cable 4. The main unit 1 contains an ink tank that stores printing ink, a circulation pump that draws ink from the ink container and supplies it to the print head 2, a pressure reducing valve that adjusts the ink to a predetermined pressure, and piping that connects these components. The ink, adjusted to the predetermined pressure, is output from the main unit 1 and supplied to the nozzles in the print head 2 via cable 4.

[0032] The print head 2 receives ink, generates ink particles internally, applies the necessary charge to these ink particles, and then deflects them to print on the object to be printed (dot printing). In addition, a display unit 5 and a reading unit 7 are provided on the front of the main body 1.

[0033] The display unit 5 displays information regarding operations that the user should perform. This display unit 5 has a touch panel input function on the top of the screen, allowing the user to input information (data) by operating it.

[0034] The reading unit 7 is provided to read information recorded on an information recording medium attached to an ink cartridge or the like. The information recording medium is, for example, an IC tag, a barcode, or a two-dimensional code (for example, QR code (registered trademark)). In the case of a QR code, the method involves picking up the ink type and comparing it with the ink type recorded in the ROM to read the corresponding ink information. Alternatively, there is a method of picking up information not recorded in the ROM from the IC and storing it in the ROM. For example, the reading unit 7 reads an IC tag and obtains ink information such as viscosity-temperature and velocity-temperature associated with the corresponding ink type.

[0035] Since users may simultaneously perform operations such as inputting data via the display unit 5 and bring the IC tag of the ink cartridge close to the reading unit 7, the reading unit 7 is located near the display unit 5.

[0036] Furthermore, a control unit (control unit 200A in Figure 2) is provided within the main unit 1, which performs control using information input from the display unit 5 and the reading unit 7. The control unit 200A controls the pump and valves within the main unit 1, as well as the nozzles and electrostatic electrodes located within the print head. Control signals (drive signals, etc.) from the control unit 200A are supplied to the print head 2 via lines arranged within the cable 4.

[0037] (Internal configuration of an inkjet printer) Next, the specific configuration of the inkjet printer 100A in this embodiment 1 will be explained using Figure 2. In Figure 2, the inkjet printer 100A includes a main unit 1, a print head 2, and a control unit 200A. A print object detector 3 is also installed outside the inkjet printer 100A. This print object detector 3 detects the object to be printed 261 (product, etc.) moving on the transport device 260 and outputs it to the control unit 200A. The control unit 200 can use this detection signal to optimally adjust the timing of the start of printing.

[0038] (Main unit configuration) In Figure 2, the main body 1 is the part of the inkjet printer 100A excluding the print head 2. That is, in this embodiment, the main body 1 includes an ink supply unit, an ink recovery unit, and a control unit 200A. The control unit 200A may be provided outside the main body 1. The ink supply unit is a device for supplying ink to the nozzles 211 of the print head 2.

[0039] The ink supply unit in this second embodiment consists of an ink tank 240 containing ink 241, a circulation pump 245, a pressure reducing valve 246, a filter 250, an auxiliary ink tank 251, a supplemental fluid tank 252, and piping 232a.

[0040] Furthermore, the ink recovery unit recovers the ink particles captured by the gutter 215 into the ink tank 240, and in this embodiment, it is composed of a recovery pump 233 and piping 232b.

[0041] The ink tank 240 is connected to the nozzle 211 by piping 232a. Meanwhile, the gutter 215 is connected to the ink tank 240 by piping 232b. Piping 232a and 232b constitute the ink flow path. A circulation pump 245 and a pressure reducing valve 246 are installed in the middle of piping 232a.

[0042] A filter 250 is installed between the circulation pump 245 and the pressure reducing valve 246. The placement of the filter 250 is not limited to the above position. The filter's primary purpose is to reduce clogging of the piping 232a and the nozzle 211. Therefore, it can be installed at any position in the piping 232a where this purpose can be achieved. Ink 241 in the ink tank 240 is drawn up by the circulation pump 245 and supplied to the nozzle 211 after its pressure is adjusted by the pressure reducing valve 246.

[0043] Furthermore, in this embodiment 1, an auxiliary ink tank 251 and a replenishment fluid tank 252 are connected to the ink tank 240, allowing for the replenishment of their respective fluids. Here, the auxiliary ink tank 251 replenishes ink when the ink in the ink tank is depleted.

[0044] The replenishment fluid tank 252 is used to supply replenishment fluid to the ink tank 240 and to properly adjust the viscosity of the ink 241. The replenishment fluid is a liquid used to replenish the solvent, which is a highly volatile component contained in the ink.

[0045] (Print head configuration) Next, the configuration of the print head 2 shown in Figure 2 will be described in detail. The print head 2 is equipped with a nozzle 211 that receives ink supplied by pressure-fed through piping 232a and discharges an ink column 221.

[0046] The nozzle 211 is equipped with a piezoelectric element 212 (vibrator) for vibrating the ejected ink column. By applying an excitation voltage from the control unit 200A to the piezoelectric element 212, vibration is applied to the ink column 221, causing it to break midway and generating ink particles 222. Due to the vibration of the ink column 221, the ink particles are continuously generated and fly at high speed.

[0047] The print head 2 also includes a charging electrode 213, a deflection electrode 214, and a gutter 215. The charging electrode 213 forms an electric field to charge the ink particles 222 generated by the nozzle 211. The deflection electrode 214 changes its trajectory according to the amount of charge of the charged ink particles 222. The gutter 215 collects ink particles that did not contribute to printing.

[0048] At the charging electrode 213, an electric charge corresponding to the shape of the characters to be printed is applied to the ink particles in flight, causing the ink particles to become charged. The charged ink particles then fly through the deflection electrode 214. A constant voltage is applied to the deflection electrode 214, and the direction of flight of each charged ink particle is deflected according to the amount of charge applied to it as it flies through the deflection electrode.

[0049] The ink particles 222 deflected by the deflection electrode 214 fly toward the object to be printed 261 being transported by the transport device 260, and by adhering to the object to be printed 261, printing is performed on the object to be printed 261.

[0050] The movement of the conveying device 260 is monitored by a rotary encoder 262. The rotary encoder 262 generates pulse signals according to the movement speed of the conveying device 260.

[0051] The movement speed detected by the rotary encoder 262 is input to the control unit 200A of the inkjet printer 100A, and is used by the control unit 200A to adjust the printing timing.

[0052] Thus, while the inkjet printer 100A is in operation, ink particles 222 are continuously ejected even when the object to be printed 261 has arrived at the printing position and printing is not taking place.

[0053] Therefore, the electrostatically controlled inkjet printer 100A is also called a continuous inkjet printer or a continuous-type inkjet printer.

[0054] (Configuration of control unit 200A) Next, the control unit 200A, which controls the print head 2 and the main unit 1, will be described. The control unit 200 controls the excitation voltage applied to the piezoelectric element 212 of the nozzle 211, the charging voltage applied to the charging electrode, the deflection voltage applied to the deflection electrode, the pressure of the ink supplied to the nozzle, etc., according to the set software parameters. Here, the elements controlled as the excitation voltage are the excitation voltage value and the excitation frequency.

[0055] Note that detailed explanations regarding the control of the ink supply and ink recovery units of the main unit 1 will be omitted below.

[0056] First, the control unit 200A in this embodiment 1 includes an MPU 201 (microprocessing unit), a ROM 202 (read-only memory), a RAM 203 (random access memory), and the like. The MPU 201 performs calculation processing to control the main unit 1 and the print head 2. The ROM 202 stores the control program and data necessary for the operation of the MPU 201. Here, the control program includes, for example, the processing shown in Figure 4. The RAM 203 temporarily stores data required during program execution. The ROM 202 records ink information for the ink 241 and software parameter values ​​optimized for control.

[0057] Ink information includes, for example, information about the ink type name or solvent of ink 241. The software used for print control of ink 241 and operation control of the inkjet printer sets various parameter values ​​for print control.

[0058] Furthermore, the control unit 200A includes an input panel 204 for inputting print content and setting values, and a display control unit 205. The input panel 204 corresponds to the touch panel of the display unit 5. The display control unit 205 controls the content displayed on the display unit 5, such as the input data and print content.

[0059] Furthermore, the control unit 200A is provided with a bus line 206. The MPU 201, ROM 202, RAM 203, input panel 204, and display control unit 205 are all connected via the bus line 206, enabling the transmission and reception of signals between each device.

[0060] Similarly, the other devices within the control unit 200A, as described below, are also connected to the bus line 206, enabling them to transmit and receive signals from each other. The bus line 206 also has the function of transmitting data signals, address signals, and control signals from the MPU 201.

[0061] Furthermore, the control unit 200A can be connected to the storage device 209, which stores programs, print data, and the like. The control unit 200A stores the data stored in the storage device 209 in its internal RAM 203.

[0062] A typical example of the storage device 209 is a USB memory stick. The control unit 200A controls the excitation voltage, pump pressure, charging voltage, deflection voltage, etc., according to the set software parameters.

[0063] The control unit 200A also includes a charging voltage generation circuit 207 and an excitation voltage generation circuit 208. The charging voltage generation circuit 207 applies a voltage to the charging electrode 213 such that the charge applied to the ink particles 222 corresponds to the amount of the character signal. The excitation voltage generation circuit 208 generates a high-frequency excitation voltage to be applied to the piezoelectric element 212 provided on the nozzle 211.

[0064] By applying an excitation voltage to the piezoelectric element 212, the ink column 221 immediately after being ejected from the nozzle 211 is vibrated, allowing for the continuous generation of ink particles. The charging voltage generation circuit 207 and the excitation voltage generation circuit 208 are also connected to the bus line 206.

[0065] Based on the information obtained from the ink viscosity measuring unit 274 and the temperature measuring unit 275 of the ink viscosity measuring unit, the ink density determination unit 280 determines the ink density and sets the temperature value of the heating element 276 installed on the print head 2. The position of the heating element 276 can be changed as appropriate, but it is preferable to install the heating element 276 on the print head 2, as shown in Figure 2. This arrangement makes it difficult for the ink heated by the heating element 276 to cool down. The method for determining the ink density and the method for determining the temperature value will be described later.

[0066] (Functions of Control Unit 200A) Next, we will explain the functions using Figure 3. The control unit 200A includes, for example, an ink density determination unit 1001A, an ink particle temperature control unit 1002A, and the like, as shown in Figure 3.

[0067] The ink concentration determination unit 1001A determines the ink concentration based on the ink viscosity provided by the ink viscosity measurement unit 274 and the ambient temperature provided by the temperature measurement unit 275, and outputs the determined ink concentration to the ink particle temperature control unit 1002A. Here, ambient temperature refers to the temperature obtained by the temperature measurement unit 275 measuring the area in which ink is ejected from the nozzle.

[0068] The ink particle temperature control unit 1002A calculates a temperature set value based on the ink concentration input from the ink concentration determination unit 1001A and outputs the calculated temperature set value to the heating heater 276. The heating heater 276 changes its temperature based on the temperature set value and heats the ink. Here, if the reading unit 7 cannot read the IC tag or reads invalid information, the heating function of the heating heater 276 may be disabled for safety reasons.

[0069] The ink density determination unit 1001A may be implemented using hardware such as an integrated circuit, or it may be implemented in software as a function of the MPU 201. For the ink viscosity measurement unit 274, a gravity-feed viscometer or a rotational viscometer can be used as the measurement method, and either may be employed.

[0070] (Method for determining ink concentration by viscosity measurement) Next, we will explain the operation using Figures 4 to 8. First, we will explain the overall operation using Figure 4. First, the ink viscosity measured by the ink viscosity measuring unit 274 is input to the ink concentration determination unit 1001A (step S001), the ambient temperature measured by the temperature measuring unit 275 is input to the ink concentration determination unit 1001A (step S002), and the ink concentration is determined in the ink concentration determination unit 1001A based on the ink viscosity and ambient temperature (step S003).

[0071] Furthermore, the ink particle temperature control unit 1002A calculates a temperature setting value based on the determined ink density (data) (step S004), and controls the temperature setting of the heating heater 276 based on the calculated temperature setting value (data) (step S005).

[0072] While the ink viscosity measurement unit 274 and temperature measurement unit 275 perform measurements continuously, the temperature control of the heating heater 276 by the control unit 200A (ink particle temperature control unit 1002A) may be performed at regular intervals (for example, every 30 minutes). The viscosity measurement frequency and calculation timing are not limited to this, as a higher measurement frequency is desirable.

[0073] Next, we will explain ink concentration based on the relationship between viscosity and ambient temperature using Figures 5 to 8. The graphs in Figures 5 to 8 are ink curves plotting the characteristics of ink concentration derived from the relationship between ink viscosity and ambient temperature.

[0074] First, the method for determining ink concentration using the ink viscosity measuring unit 274 and the temperature measuring unit 275 will be explained in detail. The ink viscosity η is a value that depends on the temperature T, as shown in (1) below.

[0075]

number

[0076] In this embodiment 1, an ink with A = 5.0 (mPa·s) and B = -0.02 ( / ℃) was used. A is the viscosity at 0℃, and B is a coefficient that depends on the ink. Also, in this embodiment 1, for convenience, the ink concentration was defined as 100% when it matched the ink viscosity expected in the viscosity measurement temperature environment. When it deviated from the ink viscosity expected in the viscosity measurement temperature environment, the ink concentration value was defined by the percentage of deviation. The definition formula is shown in equation (2) below.

[0077]

number

[0078] η is the viscosity at 100% ink concentration, and η' is the viscosity at the ink concentration being evaluated. In the example ink curve in Figure 5, the ink concentration is defined as 90% when the ink viscosity at 20°C is 3.02 mPa·s, which is 90% of the assumed viscosity η20 = 3.35 mPa·s. In the example ink curve in Figure 7, the ink concentration is defined as 110% when the ink viscosity is 3.69 mPa·s, which is 110% of the assumed viscosity η20.

[0079] (Method for determining the temperature setting value of heating element 276) In a 20°C environment, the heating element 276 was set to ensure that the ink column 221 ejected from the nozzle 211 reached 40°C. While a temperature difference between the heating element and the ink column may occur depending on the arrangement of the heating element and the nozzle, unless otherwise specified, the temperature setting of the heating element in the following text refers to the temperature of the ink column.

[0080] First, we will describe the method for determining the temperature setting of the heating element when the ink concentration is lower than 100%, using Figures 5 and 6. As a result of adding excessive replenishing fluid, the ink viscosity measured by the ink viscosity measuring unit 274 decreased to 3.02 mPa·s at 20°C, and the ink concentration was determined to be 90% according to the definition above.

[0081] In Figure 5, the viscosity of the ink column after heating to 40°C is η40 = 2.25 mPa·s if the ink concentration is 100%, but it becomes 2.02 mPa·s because the ink concentration is 90%, which could cause fluctuations in the optimal printing settings (pump pressure, excitation voltage).

[0082] Therefore, as shown in Figure 6, the temperature setting of the heating element was changed to 35°C so that the viscosity of the ink column at an ink concentration of 90% was η40 = 2.25 mPa·s. As a result, despite the decrease in ink concentration, the optimal printing settings were maintained.

[0083] Next, the method for determining the temperature setting of the heating element when the ink concentration is higher than 100% will be described using Figures 7 and 8. As a result of insufficient addition of the supplemental fluid, the ink viscosity measured by the ink viscosity measuring unit 274 rose to 3.69 mPa·s at 20°C, and the ink concentration was determined to be 110% according to the definition above.

[0084] In Figure 7, the viscosity of the ink column after heating to 40°C is η40 = 2.25 mPa·s if the ink concentration is 100%, but it becomes 2.47 mPa·s because the ink concentration is 110%, which could cause fluctuations in the optimal printing settings (pump pressure, excitation voltage).

[0085] Therefore, as shown in Figure 8, the temperature setting of the heating element was changed to 45°C so that the viscosity of the ink column at an ink concentration of 110% was η40 = 2.25 mPa·s. As a result, despite the decrease in ink concentration, the optimal printing settings were maintained.

[0086] The ink concentration characteristics derived from the relationship between ink viscosity and ambient temperature described above may be set by the algorithm of the program executed by the MPU201, or they may be stored in the memory device 209 and read when the MPU201 program is executed.

[0087] In this embodiment 1, the measurement of the ejection speed may also be taken into consideration. In this case, a speed sensor is placed near the strobe 272 of the print head 2. The control unit 200B can then measure the ejection speed detected by the speed sensor and take that into consideration when setting the print settings.

[0088] Regarding the relationship between ejection speed and ambient temperature, ejection speed tends to increase as the ambient temperature rises, but tends to decrease as the ink density decreases. On the other hand, even if the heating temperature is set low, the ejection speed remains the same before and after the setting, even if the ink density changes. Also, regarding the relationship between ejection speed and ambient temperature, even at the same ambient temperature, a faster ejection speed tends to decrease the ink density. On the other hand, even if the heating temperature is set high, the ejection speed remains the same before and after the setting, even if the ink density changes.

[0089] Therefore, by adjusting the temperature setting of the heating element 276 so that the ink particle ejection speed reaches the target speed, the optimal printing settings can be maintained even if the ink density decreases or increases. The relationship between the ejection speed and ambient temperature described above will be explained with reference to the drawings in Embodiment 2, which will be described later.

[0090] The ink density characteristics derived from the relationship between ejection speed and ambient temperature described above may be set by the algorithm of the program executed by the MPU201, or they may be stored in the memory device 209 and read when the MPU201 program is executed.

[0091] As described above, according to this embodiment 1, the control unit 200A of the inkjet printer 100A determines the ink concentration in the ink tank 240 from the ambient temperature and ink viscosity, and determines the ink heating setting so that the ink viscosity or ink ejection speed at ejection is constant, thus enabling printing settings that are independent of ink concentration. As a result, sufficient adaptation to changes in ink concentration is achieved, and robustness is improved.

[0092] [Embodiment 2] Next, Embodiment 2 will be described using Figures 9 to 15. In Embodiment 2, an inkjet printer will also be used as an example of a printing device. First, the configuration will be described using Figures 9 and 10.

[0093] This second embodiment has the same basic configuration as the first embodiment described above, but differs in that, for determining the ink concentration, it uses the ink particle ejection speed v (m / s) using a camera 271, a strobe 272, or a speed sensor 273 that detects the ink ejection speed, instead of the ink viscosity measuring unit 274 and the temperature measuring unit 275 of the ink viscosity measuring unit. This speed sensor 27 determines the ink ejection speed based on an image of the ink particles, a capacitance sensor, or electrical signal information. The electrical signal information includes information on the difference in the passage time between two or more points in the print head until the charged ink particles are collected in the gutter.

[0094] The control unit 200B of this second embodiment includes, for example, an ink density determination unit 1001B and an ink particle temperature control unit 1002B, as shown in Figure 10, as part of its functional configuration.

[0095] The ink density determination unit 1001B determines the ink density based on the ink ejection speed output from the speed sensor 273, and outputs the determined ink density to the ink particle temperature control unit 1002B.

[0096] The ink particle temperature control unit 1002B calculates a temperature set value based on the ink concentration input from the ink concentration determination unit 1001B, and outputs the calculated temperature set value to the heating heater 276. The heating heater 276 changes the temperature based on that temperature set value.

[0097] (Method for determining ink density by speed measurement) Next, we will explain the operation using Figures 11 to 15. First, we will explain the overall operation using Figure 11. Figure 11 is a flowchart explaining the operation in this second embodiment. In the control unit 200B, the ink density determination unit 1001B receives the ink ejection speed detected by the speed sensor 273 as input (step S011) and determines the ink density based on that ejection speed (step S012).

[0098] Furthermore, the ink particle control unit 1002B calculates a temperature setting value based on the ink concentration, which is data indicating the determination result, and determines it as control data (step S013). Based on the calculated temperature setting value (data), it controls the temperature setting of the heating heater 276 (step S014).

[0099] Although the speed sensor 273 measures continuously, the temperature control of the heating heater 276 by the control unit 200B (ink particle temperature control unit 1002B) may be performed at regular intervals (for example, every 30 minutes).

[0100] Furthermore, Figures 12 to 15 will be used to explain the details. The graphs in Figures 12 to 15 are ink curves plotting the characteristics of ink concentration derived from the relationship between ejection speed and ambient temperature.

[0101] First, we will explain how to derive v using camera 271 and strobe 272. By flashing strobe 272 in synchronization with the excitation frequency f (Hz) of piezoelectric element 212, it is possible to observe the ink particles ejected from the nozzle in a still image.

[0102] The inter-ink particle distance λ(m) is extracted from the analysis of the image captured using camera 271, i.e., the still image of the ink particles, and v is calculated from the following equation (3).

[0103]

number

[0104] Next, we will explain how to derive v using the velocity sensor 273. The velocity sensor 273 is not particularly limited as long as it is a sensor capable of observing the velocity of ink particles ejected from the nozzle. For example, the following configurations are possible.

[0105] Two capacitance sensors are placed at a distance C (m) apart in the path through which ink particles fly from the nozzle to the gutter. When ink particles ejected from the nozzle are charged by a charging electrode and pass through the two capacitance sensors, induced power is generated in the capacitance sensors. From the time difference Δt between the generation of organic power in the two sensors, v is calculated from equation (4) below.

[0106]

number

[0107] Alternatively, one capacitance sensor may be used, and the time difference Δt may be defined as the time it takes for the ink particles to be captured in the gutter. In that case, C is the distance between the capacitance sensor and the gutter. Since the ejection speed v is inversely proportional to the viscosity, the ink concentration was determined by the following equation (5) based on the definition of ink concentration using the ink viscosity ratio described above.

[0108]

number

[0109] v is the ejection speed at 100% ink concentration, and v' is the ejection speed at the target ink concentration.

[0110] (Method for determining the temperature setting value of the heating element) In a 20°C temperature environment, the heating element 276 was set to ensure that the ink column 221 ejected from the nozzle 211 reached 40°C. The ejection speed measured by the speed sensor 273 with 100% ink density was v40 = 20.0 m / s at 40°C.

[0111] First, we will describe the method for determining the temperature setting of the heating element 276 when the ink concentration is lower than 100%, using Figures 12 and 13. As a result of adding an excess of the supplementing fluid, the ejection speed measured by the speed sensor 273 increased to 22.2 m / s at 20°C, as shown in Figure 12. Since the ejection speed v is inversely proportional to viscosity, the ink concentration was determined to be 90% based on the definition of ink concentration described above.

[0112] As a result, there was a risk of fluctuations occurring in the optimal printing settings (pump pressure, excitation voltage). Therefore, as shown in Figure 13, the temperature setting of the heating element 276 was changed to 35°C so that the ink particle ejection speed was v40 = 20.0 m / s at an ink concentration of 90%. As a result, despite the decrease in ink concentration, the optimal printing settings were maintained.

[0113] Next, we will describe the method for determining the temperature setting of the heating element 276 when the ink density is higher than 100%, using Figures 14 and 15. As a result of insufficient input of the supplemental fluid, the ejection speed measured by the speed sensor 273 decreased to 18.2 m / s at 20°C, as shown in Figure 14.

[0114] Since the ejection speed v is inversely proportional to viscosity, the ink concentration was determined to be 110% based on the above definition of ink concentration. As a result, there was a risk of fluctuations occurring in the optimal printing settings (pump pressure, excitation voltage).

[0115] Therefore, as shown in Figure 15, the temperature setting of the heating element 276 was changed to 35°C so that the ink particle ejection speed was v40 = 20.0 m / s at an ink concentration of 110%. As a result, despite the increase in ink concentration, the optimal printing settings were maintained.

[0116] The ink density characteristics derived from the relationship between ejection speed and ambient temperature described above may be set by the algorithm of the program executed by the MPU201, or they may be stored in the memory device 209 and read when the MPU201 program is executed.

[0117] As described above, according to this embodiment 2, the control unit 200B of the inkjet printer 100B determines the ink concentration in the ink tank 240 from the ejection speed detected by the speed sensor 273, and determines the ink heating setting so that the ink viscosity or ink ejection speed at the time of ejection remains constant. As a result, printing (including printing) settings that are independent of ink concentration are possible. Consequently, sufficient adaptation to changes in ink concentration is achieved, and robustness is improved.

[0118] [Embodiment 3] Next, Embodiment 3 will be described using Figures 16 and 17. In Embodiment 3, an inkjet printer will also be used as an example of a printing device.

[0119] This third embodiment has the same basic configuration as the second embodiment, but is characterized by using a camera 271, a strobe 272, or a flight speed sensor 273 to determine the ink particle ejection speed v (m / s) and adjusting the temperature of the heating heater 276 without determining the ink concentration from the ejection speed.

[0120] The control unit 200C of this embodiment 3 includes, for example, an ink particle temperature control unit 1002C, as shown in Figure 16, as part of its functional configuration.

[0121] The ink density determination unit 1001B determines the ink density based on the ink ejection speed output from the speed sensor 273, and outputs the determined ink density to the ink particle temperature control unit 1002B.

[0122] The ink particle temperature control unit 1002B calculates a temperature setpoint based on the ejection speed output from the speed sensor 273 and outputs this calculated temperature setpoint to the heating heater 276. The heating heater 276 changes the temperature based on this temperature setpoint.

[0123] Furthermore, regarding the operation, as shown in Figure 17, in the control unit 200C, the ink particle temperature control unit 1002C receives the ink ejection speed detected by the speed sensor 273 as input (step S021), calculates a temperature set value based on that ejection speed and determines it as control data (step S022), and controls the temperature setting of the heating heater 276 based on the calculated temperature set value (data) (step S023).

[0124] Although the speed sensor 273 measures continuously, the temperature control of the heating heater 276 by the ink particle temperature control unit 1002C of the control unit 200C may be performed at regular intervals (for example, every 30 minutes).

[0125] Furthermore, even when controlling the temperature solely by the ejection speed, the characteristics of ink concentration derived from the relationship between ejection speed and ambient temperature, as used in Embodiment 2 described above, can be utilized. In other words, if the ejection speed is known, the ambient temperature can be determined, and the temperature can be adjusted to match the appropriate ink concentration based on the relationship between ejection speed and ambient temperature.

[0126] In the aforementioned Embodiment 2, the configuration is based on determining the ink concentration in the ink tank 240 from the ejection speed detected by the speed sensor 273. According to Embodiment 3 described above, the control unit 200C determines the ink heating setting so that the ink viscosity or ink ejection speed at the time of ejection remains constant, so that printing (including printing) settings that are independent of ink concentration are possible. As a result, sufficient adaptation to changes in ink concentration is achieved, and robustness is improved.

[0127] [Embodiment 4] Next, the printing system 400 of this embodiment 3 will be explained using Figure 18. In this embodiment 4, an inkjet printer will also be used as an example of a printing device.

[0128] The printing system 400 consists of an inkjet printer 100D and a printing control device 200D. The inkjet printer 100D and the printing control device 200D are connected via a communication network 300. The communication network 300 may be wired or wireless.

[0129] The inkjet printer 100D of this embodiment 4 corresponds to the inkjet printer 100A of embodiment 1 described above, with the characteristic functions of the control unit 200A (for example, the ink density determination unit 280) removed. The same exclusion applies to the other embodiments 2 or 3, and these correspond to structural variations.

[0130] The print control device 200D in this embodiment 4 is a PC (Personal Computer), a mobile terminal, a server, etc. The print control device 200D is composed of, for example, a processor such as a CPU (Central Processing Unit), a storage device such as memory and an HDD (Hard Disk Drive), an input device such as a keyboard, mouse, or touch panel, a display device such as a display, and a communication device such as a network I / F.

[0131] The processor executes a program stored in the memory device to achieve functions similar to, for example, the optimal phase detection circuit 210 and the ink density determination unit 280 of Embodiment 1.

[0132] As described above, according to this embodiment 4, the printing system 400 is composed of a printing control device 200D and a static charge-controlled inkjet printer (for example, an inkjet printer 100D), and the control unit is provided outside the static charge-controlled inkjet printer, thereby enabling the static charge-controlled inkjet printer to be miniaturized and controlled remotely. In this case as well, sufficient adaptation to changes in ink density is possible, and robustness is improved.

[0133] In this embodiment 4, since the print control device 200D controls the printing of the inkjet printer 100D via the network 300, it goes without saying that it may also control the printing of other inkjet printers to respond to similar changes in ink density. In this case, the control unit D is connected to multiple different inkjet printers in a communicative manner and controls the temperature setpoint for each inkjet printer to execute the printing process. The connection to each inkjet printer may be wired or wireless.

[0134] Furthermore, as a variation of Embodiment 1 described above, a configuration combining viscosity measurement and velocity measurement is also possible, in which case there is the effect of double-checking. Of course, the same applies to Embodiments 2 and 3.

[0135] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described.

[0136] Furthermore, it is possible to replace some of the configurations of one embodiment described above with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of one embodiment described above. In addition, it is possible to add, delete, or replace some of the configurations of each embodiment with those of other embodiments.

[0137] Furthermore, some or all of the above configurations and functions may be implemented in hardware, for example, by designing them as integrated circuits. Alternatively, the above configurations and functions may be implemented in software by having the processor interpret and execute programs that implement each function. Information such as programs, tables, and files that implement each function can be stored in memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD. [Explanation of Symbols]

[0138] 1 Main unit 2 Print head 4 Cables 5 Display section 7. Reading Unit 100A, 100B, 100C, 100D inkjet printers 200A, 200B, 200C Control Unit 200D Printing Control Unit 201 MPU 202 ROM 203 RAM 204 Input Panel 205 Display Control Unit 206 Bus Line 211 Nozzles 240 Ink Tanks 241 Ink 271 Camera 272 Strobe lighting 273 Speed ​​Sensor 274 Ink viscosity measurement section 275 Temperature measurement section 276 Heating heater 300 Communication Networks 400 Printing Systems 1001A, 1001B Ink density determination unit 1002A, 1002B, 1002C Ink Particle Temperature Control Unit

Claims

1. An inkjet recording apparatus comprising a temperature measuring unit for measuring ambient temperature and an ink viscosity measuring unit for measuring ink viscosity, wherein ink is ejected and printing is performed, The system includes a control unit that determines the ink concentration based on the ambient temperature measured by the temperature measuring unit and the ink viscosity measured by the ink viscosity measuring unit, and controls the temperature set value of the ink to be dispensed based on the determined ink concentration. An inkjet recording apparatus characterized by printing on a printable object based on the control of the control unit.

2. An inkjet recording device equipped with a speed sensor for detecting the ink ejection speed, which ejects ink and performs printing processing, The system includes a control unit that controls the temperature setpoint of the ejected ink based on the ejection speed measured by the speed sensor, An inkjet recording apparatus characterized by printing on a printable object based on the control of the control unit.

3. In the inkjet recording apparatus according to claim 1 or claim 2, An inkjet recording apparatus characterized by having a heating heater whose temperature set value is controlled by the control unit, and a print head that ejects heated ink.

4. In the inkjet recording apparatus according to claim 1, The control unit is characterized in that it determines the ink concentration based on the characteristics of the ink concentration derived from the relationship between the ink viscosity and ambient temperature for each type of ink.

5. In the inkjet recording apparatus according to claim 4, An inkjet recording apparatus characterized in that an external information recording medium records ink information indicating the characteristics of the ink density, and further has a reading unit for reading the ink information from the information recording medium.

6. In the inkjet recording apparatus according to claim 2, The system includes a determination unit that determines the ink concentration based on the ejection speed measured by the speed sensor, The control unit controls the temperature set value of the ink to be ejected based on the ink concentration determined by the determination unit, thereby enabling the inkjet recording apparatus.

7. In the inkjet recording apparatus according to claim 6, The control unit controls the temperature setpoint based on the characteristics of the ink concentration derived from the relationship between the ejection speed and the ambient temperature, thereby enabling the inkjet recording apparatus.

8. In the inkjet recording apparatus according to claim 2, The inkjet recording apparatus is characterized in that the speed sensor determines the ink ejection speed based on an image of the ink particles, a capacitance sensor, or electrical signal information.

9. In the inkjet recording apparatus according to claim 8, The print head includes a gutter for ejecting the ink and for collecting the ink particles, The speed sensor is connected to a print head equipped with a gutter for collecting the ink particles. The inkjet recording apparatus is characterized in that the electrical signal information includes information on the difference in the passage time of the charged particles at two or more points within the print head until they are collected in the gutter.

10. A print control device for an inkjet recording apparatus, having a temperature measuring unit for measuring ambient temperature and an ink viscosity measuring unit for measuring ink viscosity, and ejecting ink to perform printing processing, A determination unit that determines the ink concentration based on the ambient temperature measured by the temperature measuring unit and the ink viscosity measured by the ink viscosity measuring unit, A control unit that controls the temperature set value of the ink to be ejected based on the ink concentration determined by the determination unit, A printing control device characterized by comprising:

11. A print control device for an inkjet recording apparatus that has a speed sensor for detecting the ink ejection speed and ejects ink to perform printing processing, A printing control device characterized by comprising a control unit that controls the temperature set value of the ejected ink based on the ejection speed measured by the speed sensor.

12. A print control device according to claim 11, wherein the control unit is connected to a plurality of inkjet recording devices, and the control unit controls the temperature set value for each of the plurality of inkjet recording devices.

13. A printing control method for an inkjet recording device that ejects ink to perform printing, The inkjet recording device has a speed sensor and a heating heater, and the printing control method is characterized by determining an ink temperature set value based on the ink ejection speed detected by the speed sensor, and controlling the ink temperature in the heating heater based on the temperature set value.

14. A printing control method according to claim 13, characterized in that the temperature set value is controlled based on the characteristics of the ink concentration derived from the relationship between the ejection speed and the ambient temperature.

Images