WO2023162421A1

WO2023162421A1 - Printing device and printing method

Info

Publication number: WO2023162421A1
Application number: PCT/JP2022/046258
Authority: WO
Inventors: 晃澄岡本; 紗也加北村; 芳樹水野
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス
Priority date: 2022-02-25
Filing date: 2022-12-15
Publication date: 2023-08-31
Also published as: JP2023124417A

Abstract

Provided is technology capable of reducing the temperature fluctuation range of ink in a discharge head even if the amount of ink flowing into the discharge head fluctuates. A flow rate prediction unit (93) predicts the flow rate of ink flowing from an ink tank (311) to a discharge head (21) after a predetermined time from the present time. A first heater control unit (91) controls a heater unit (351) on the basis of a flow rate (Fp1) predicted by the flow rate prediction unit (93). An outlet temperature sensor (371) measures a temperature (Te3) of the ink flowing from the heater unit (351) to the discharge head (21). A second heater control unit (92) controls the heater unit (351) on the basis of the difference between the temperature (Te3) measured by the outlet temperature sensor (371) and a preset target temperature (Ttg).

Description

Printing device and printing method

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

Conventionally, there has been known a printing apparatus that forms an image on a base material by ejecting ink from an ejection head onto the surface of the base material while conveying the base material in a continuous form by a roll-to-roll method. In this type of printing apparatus, ink viscosity management is generally important.

For example, when the temperature of the ink drops, the viscosity increases, which causes uneven ejection, which causes problems such as deviation of the landing position of the ink and the occurrence of streaks. Therefore, in some cases, a mechanism for heating the ink is provided for the purpose of keeping the ink temperature constant.

For example, in Patent Document 1, ink is circulated in a circulation path connected to an ejection head, and the ink flowing through the circulation path is heated by a hot water unit.

JP 2016-055501 A

However, the temperature of the ink in the ejection head may fluctuate irregularly according to the amount of ink flowing into the ejection head from an ink tank that stores unused ink. For this reason, there is a possibility that the temperature fluctuation range of the ink may become large only by uniformly heating the ink in the ejection head.

An object of the present invention is to provide a technique capable of reducing the temperature fluctuation range of the ink in the ejection head even if the amount of ink flowing into the ejection head fluctuates.

In order to solve the above problems, a first aspect is a printing apparatus, comprising: an ejection head for ejecting ink onto a surface of a substrate; an ink tank capable of storing the ink; An ink supply unit that supplies ink, a heater unit that heats the ink flowing from the ink tank to the ejection head, and a flow rate prediction unit that predicts the flow rate of the ink that will flow from the ink tank to the ejection head after a predetermined time from the present time. a first heater control unit that controls the heater unit based on the flow rate predicted by the flow rate prediction unit; a first temperature measurement unit that measures the temperature of ink flowing from the heater unit to the ejection head; A second heater control section for controlling the heater section based on a difference between the temperature measured by the first temperature measurement section and a preset target temperature.

A second aspect is the printing apparatus of the first aspect, wherein the flow rate prediction unit predicts the flow rate based on ejection information indicating the amount of ink ejected from the ejection head.

A third aspect is the printing apparatus of the second aspect, further comprising an ejection control section that controls the ejection head based on print data, and the ejection information includes the print data.

A fourth aspect is the printing apparatus according to any one of the first aspect to the third aspect, further comprising a second temperature measurement section that measures the temperature of the ink in the ink tank, and the first heater control section controls the heater section based on the difference between the temperature measured by the second temperature measurement section and a preset target temperature.

A fifth aspect is the printing apparatus according to any one of the first aspect to the fourth aspect, further comprising a third temperature measurement section for measuring a temperature outside the ink tank, wherein the first heater control section The heater section is controlled based on the temperature measured by the third temperature measurement section.

A sixth aspect is the printing apparatus according to any one of the first aspect to the fifth aspect, further comprising a flow rate measuring section for measuring a flow rate of ink supplied from the ink tank to the ejection head, The 1-heater control section controls the heater section based on the flow rate measured by the flow rate measurement section.

A seventh aspect is a printing method comprising: a) a prediction step of predicting the flow rate of ink flowing from the ink tank to the ejection head after a predetermined time from the current time; and c) measuring the temperature of the ink flowing from the heater to the ejection head. and b-2) controlling the heater unit based on the difference between the temperature measured in c) and a preset target temperature.

According to the printing apparatuses of the first to sixth aspects, the temperature fluctuation width can be reduced by controlling the heater section based on the predicted value of the flow rate of the ink flowing to the ejection head.

According to the printing apparatus of the second aspect, the flow rate can be accurately predicted based on the ink ejection amount.

According to the printing device of the third aspect, the flow rate can be accurately predicted based on the print data.

According to the printing apparatus of the fourth aspect, by controlling the heater section based on the temperature difference between the target temperature and the temperature of the ink in the ink tank, the temperature of the ink in the ejection head can be appropriately adjusted.

According to the printing apparatus of the fifth aspect, the temperature of the ink inside the ejection head can be appropriately adjusted by controlling the heater section based on the temperature outside the ink tank.

1 is a diagram showing the configuration of a printing apparatus according to an embodiment; FIG. 3 is a block diagram showing connections between a control unit and each unit of the printing apparatus; FIG. It is a control block diagram for controlling a heater part. FIG. 5 is a diagram showing temperature fluctuations of ink at the outlet position of the heater section; FIG. 5 is a diagram showing the correspondence relationship between the temperature of ink at the inlet position of the heater section and the width of temperature fluctuation;

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. It should be noted that the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them. In the drawings, for ease of understanding, the dimensions and numbers of each part may be exaggerated or simplified as necessary.

<1. embodiment>
FIG. 1 is a diagram showing the configuration of a printing apparatus 1 according to an embodiment. The printing device 1 is a device that performs printing using an inkjet method. More specifically, the printing apparatus 1 ejects ink from the plurality of ejection heads 21 to 24 onto the substrate W while transporting the substrate W in the form of a long belt with the plurality of transportation rollers 12. record an image on the surface of the The substrate W is, for example, a flexible medium such as printing paper, resin film, cardboard, or metal thin film.

As shown in FIG. 1, the printing apparatus 1 includes a transport mechanism 10, a printing section 20, a supply section 30, an encoder 60, a camera 70, a plurality of various sensors 80, and a control section 9.

The transport mechanism 10 transports the base material W in the transport direction along the longitudinal direction of the base material W along a predetermined transport route. The conveying mechanism 10 has an unwinding roller 11 , a plurality of conveying rollers 12 and a winding roller 13 . A substrate W is stretched over these rollers. The base material W is unwound from the unwinding roller 11 and conveyed along a predetermined conveying path while being supported by the plurality of conveying rollers 12 . Each transport roller 12 guides the substrate W to the downstream side of the transport path by rotating around an axis extending in a direction perpendicular to the transport direction. The substrate W transported by the plurality of transport rollers 12 is wound around the take-up roller 13 . A tension is applied to the substrate W in the transport direction. This suppresses slackness and wrinkles of the base material W during transportation.

The transport mechanism 10 further has a motor 14 that rotates some rollers (hereinafter referred to as "drive rollers"). The transport mechanism 10 may include multiple motors 14 . Motor 14 is electrically connected to controller 9 . When the motors 14 are driven, a command value for rotating the motors 14 is input to each motor 14 from the control unit 9 . Then, the motor 14 is driven according to the command value, and the drive roller rotates. As a result, the base material W is conveyed from the unwinding roller 11 toward the winding roller 13 .

The printing unit 20 is a processing unit that ejects ink droplets (hereinafter referred to as "ink droplets") onto the base material W conveyed by the conveying mechanism 10 . The printing unit 20 has a plurality (four in this example) of ejection heads 21-24. The ejection heads 21-24 have the same structure. In addition, the ejection heads 21 to 24 are arranged at intervals along the direction in which the substrate W is conveyed. Note that the substrate W moves substantially parallel to the arrangement direction of the plurality of ejection heads 21-24 below the plurality of ejection heads 21-24. At this time, the surface (printing surface) of the base material W faces upward (toward the ejection heads 21 to 24).

In addition, each of the ejection heads 21-24 has an internal space capable of storing ink and a plurality of nozzles (not shown). A plurality of nozzles are arranged in parallel with the width direction of the substrate W on the lower surface of each of the ejection heads 21-24. Further, each of the plurality of nozzles has a piezo element as a pressure generating element (not shown) and an ejection port communicating with the internal space of each of the ejection heads 21-24. During ink ejection, the ink flows down from the internal space to the vicinity of the ejection port. Then, the ink in the vicinity of the ejection port is pressurized by the action of the piezo element, thereby ejecting droplets of ink from the ejection port. The ink ejection method may be a so-called thermal method in which a heater is used as a pressure generating element to heat the ink in the vicinity of the ejection port to generate bubbles.

Each of the ejection heads 21 to 24 directs from a plurality of nozzles toward the upper surface of the base material W, each of K (black), C (cyan), M (magenta), and Y (yellow), which are color components of a multicolor image. of ink droplets are respectively ejected. That is, the ejection head 21 ejects K-color ink droplets as a processing substance onto the upper surface of the base material W at the first printing position P1, which is the processing position on the transport path. The ejection head 22 ejects C-color ink droplets as a processing substance onto the upper surface of the substrate W at a second printing position P2, which is a processing position downstream of the first printing position P1. The ejection head 23 ejects M-color ink droplets as a processing substance onto the upper surface of the substrate W at a third printing position P3, which is a processing position downstream of the second printing position P2. The ejection head 24 ejects Y-color ink droplets as a processing substance onto the upper surface of the substrate W at a fourth printing position P4, which is a processing position downstream of the third printing position P3.

In this embodiment, the first printing position P1, the second printing position P2, the third printing position P3, and the fourth printing position P4 are arranged at equal intervals along the transport direction of the base material W. The ejection heads 21 to 24 respectively record monochromatic images on the top surface of the substrate W by ejecting ink droplets. Then, a multicolor image is formed on the upper surface of the substrate W by superimposing the four monochromatic images. Further, each of the ejection heads 21 to 24 can print on the upper surface of the base material W by ejecting ink droplets.

The supply unit 30 is a unit that supplies ink to the ejection heads 21-24. The supply unit 30 has a plurality (four in this example) of ink supply systems 31 . A plurality of ink supply systems 31 are connected to the ejection heads 21 to 24, respectively, and supply inks of corresponding colors to the ejection heads 21 to 24, respectively. The ink supply system 31 that supplies ink to the ejection head 21 will be described below.

The ink supply system 31 has an ink tank 311 , a pipe 321 , a pump 331 , a flow meter 341 , a heater section 351 , an in-tank temperature sensor 361 , an outlet temperature sensor 371 , and a liquid level sensor 381 .

The ink tank 311 stores unused ink. One end of the pipe 321 is connected to the internal space of the ejection head 21 . The other end of the pipe 321 is connected to the ink tank 311 . A pump 331 is installed in the pipe 321 . A pump 331 generates a flow of ink from the ink tank 311 toward the ejection head 21 . The pump 331 is, for example, a pump equipped with a brushless motor. The pipe 321 and the pump 331 are an example of an “ink supply unit” that supplies ink from the ink tank 311 to the ejection head 21 . The ink in the ink tank 311 may be sent to the ejection head 21 by a pressurizing mechanism that pressurizes the inside of the ink tank 311 . In this case, the pressure mechanism functions as an "ink supply section".

The flow meter 341 is installed in the pipe 321. A flow meter 341 measures the flow rate of ink flowing through the pipe 321 . The flow meter 341 transmits a signal indicating the measured flow rate to the controller 9 .

When ink droplets are ejected from the ejection head 21 toward the substrate W, the amount of ink in the ejection head 21 decreases. The controller 9 inputs a drive value to the pump 331 according to the decrease in the amount of ink in the ejection head 21 . As a result, the pump 331 is driven according to the drive value, and an amount of ink corresponding to the decrease in ink in the ejection head 21 is supplied from the ink tank 311 to the ejection head 21 . Similarly to the ejection head 21, the other ejection heads 22-24 are supplied with ink from the corresponding ink supply system 31, respectively.

The heater section 351 heats ink supplied to the ejection head 21 . The heater section 351 is installed on the pipe 321 . The heater section 351 is positioned between the pump 331 and the flow meter 341 . The heater section 351 heats the ink flowing through the pipe 321 .

The in-tank temperature sensor 361 (second temperature measuring unit) is installed inside the ink tank 311 . The in-tank temperature sensor 361 measures the temperature of the ink stored in the ink tank 311 . The in-tank temperature sensor 361 transmits a signal indicating the measured temperature to the controller 9 .

The outlet temperature sensor 371 (first temperature measurement unit) is installed on the pipe 321 . The outlet temperature sensor 371 is positioned between the heater section 351 and the ejection head 21 . The outlet temperature sensor 371 measures the temperature of ink flowing from the heater section 351 to the ejection head 21 via the pipe 321 . In this example, the outlet temperature sensor 371 is provided at the outlet position of the heater section 351 . Therefore, the temperature of the ink immediately after passing through the heater section 351 is measured. However, the outlet temperature sensor 371 may be positioned closer to the ejection head 21 than the heater section 351 . The outlet temperature sensor 371 transmits a signal indicating the measured temperature to the controller 9 .

The liquid level sensor 381 is a sensor for measuring the amount of ink in the ejection head 21 and measures the height of the ink liquid level in the ejection head 21 . The liquid level sensor 381 is, for example, a non-contact sensor that detects the height of the liquid level using ultrasonic waves. The liquid level sensor 381 transmits a signal indicating the measured liquid level to the controller 9 .

The supply unit 30 has an outside air temperature sensor 39 (third temperature measurement unit). The outside air temperature sensor 39 is positioned outside the ink tank 311 and measures the outside air temperature outside the ink tank 311 .

The encoder 60 is attached to the axis of one of the plurality of transport rollers 12 (the transport roller 121 in the example of FIG. 1). The encoder 60 detects the rotation of the transport roller 121 and outputs a continuous pulse signal synchronized with the rotation of the transport roller 121 to the controller 9 . The continuous pulse signal is data that reflects changes over time in the transport speed of the substrate W transported by the plurality of transport rollers 12 including the transport roller 121 .

The camera 70 is an imaging device that captures the printed surface (front surface) of the base material W that has passed through the printing unit 20 . The camera 70 is arranged to face the printing surface of the base material W at an imaging position P5 downstream of the four ejection heads 21 to 24 in the transport path. The camera 70 has, for example, a line sensor in which a plurality of imaging devices such as CCDs and CMOSs are arranged in the width direction. While the substrate W is being transported by the transport mechanism 10, the camera 70 acquires image data of the printed substrate W by photographing the printed surface of the substrate W at predetermined intervals. The camera 70 transmits the obtained image data to the control section 9 .

A plurality of various sensors 80 are measuring instruments for measuring the transport state of the substrate W, in addition to those listed above. A plurality of various sensors 80 are provided at a plurality of measurement points on the transport path of the substrate W. As shown in FIG. Various sensors 80 acquire measured values at respective measurement locations. The measurement items of the various sensors 80 include, for example, the vertical displacement of the base material W (the amount of displacement in the direction perpendicular to the base material W), the tension applied to the base material W, the position of the edge of the base material W in the width direction, etc. can be included. Various sensors 80 that measure the same item may be arranged at a plurality of positions on the transport route. While the substrate W is being transported by the transport mechanism 10, the plurality of various sensors 80 constantly measure the state of each measurement location. The various sensors 80 then transmit signals indicating the obtained measurement values to the control unit 9 .

FIG. 2 is a block diagram showing connections between the control unit 9 and each unit of the printing apparatus 1. As shown in FIG. The control unit 9 controls operations of the printing apparatus 1 . The control unit 9 has a processor 901 configured by a CPU or the like, and a storage unit 903 configured by a RAM, hard disk, or the like. Storage unit 903 stores program 90P and various data.

The program 90P is provided by the recording medium M. The program 90P is recorded on the recording medium M so as to be readable by the control section 9, which is a computer. The recording medium M is, for example, a USB (Universal Serial Bus) memory, an optical disk such as a DVD (Digital Versatile Disc), or a magnetic disk.

The control unit 9 controls the motor 14 of the transport mechanism 10, the ejection heads 21 to 24 of the printing unit 20, the pump 331 of the supply unit 30, the flow meter 341, the heater unit 351, the tank internal temperature sensor 361, the outlet temperature sensor 371, It is communicably connected to the liquid level sensor 381 and the outside air temperature sensor 39 . Also, the control unit 9 is communicably connected to the encoder 60, the camera 70, and various sensors 80. FIG.

The ejection control unit 90, the first heater control unit 91, the second heater control unit 92, the flow rate prediction unit 93, and the learning unit 94 shown in FIG. 2 are functions realized by the processor 901 executing the program 90P. . The ejection control unit 90 controls ejection of ink from the ejection heads 21 to 24 based on print data indicating an image to be printed on the base material W. FIG. The first heater control section 91 and the second heater control section 92 control the heater section 351 . Functions of the first heater control section 91, the second heater control section 92, the flow rate prediction section 93, and the learning section 94 will be described with reference to FIG.

<Control of heater>
FIG. 3 is a control block diagram for controlling the heater section 351. As shown in FIG. In the following description, the case of controlling the heater section 351 of the ink supply system 31 connected to the ejection head 21 will be mainly described. Also in the ink supply system 31 connected to the ejection heads 22-24, control similar to that shown in FIG. 3 is performed.

The first heater control section 91 and the second heater control section 92 output heater command values CV1 and CV2 to the heater section 351, respectively. As an example, the heater command values CV1 and CV2 are values indicating power values applied to heaters included in the heater section 351 . The heater unit 351 heats the heater according to the sum of the input heater command values CV1 and CV2.

The first heater control unit 91 executes feedforward (FF) control. The first heater control unit 91 controls the heater command value CV1 so that the temperature of the ink in the ejection head 21 reaches a preset target temperature Ttg after a predetermined time (for example, after several seconds or several tens of seconds). to output

Specifically, the first heater control section 91 controls the heater section 351 based on the flow rate predicted by the flow rate prediction section 93 . The flow rate prediction unit 93 uses the flow rate prediction model 931 to predict the flow rate Fp1 of the ink flowing into the ejection head 21 after a predetermined period of time. The flow rate Fp1 may be the flow rate at a point in time in the future, or may be a flow rate fluctuation waveform that indicates the time fluctuation of the flow rate. The flow rate prediction model 931 is stored in the storage section 903 . The flow rate prediction model 931 outputs the flow rate Fp1 after a predetermined time from the input variable Vi.

The input variables Vi are the print pattern indicated by the print data, the head driving waveform output to the ejection head 21 by the control unit 9 to drive the ejection head 21, the ink ejection count, and the or a combination of these information. The print data indicating the print pattern, the head drive waveform, the ink ejection count, and the ink liquid surface height are ejection information indicating the amount of ink ejected from the ejection head 21 . By using the discharge information as the input variable Vi, the flow rate after a predetermined time can be predicted with high accuracy. In particular, by including the print pattern indicated by the print data in the input variable Vi, the flow rate after a predetermined time can be predicted with high accuracy.

The learning unit 94 performs machine learning to construct the flow rate prediction model 931. The control unit 9 stores the flow rate measured by the flow meter 341 in the storage unit 903 . The learning unit 94 learns the relationship between the input variable Vi and the flow rate measured by the flow meter 341 after a predetermined time from the time corresponding to the input variable Vi based on a supervised machine learning algorithm, thereby forming a flow rate prediction model. Build 931.

The machine learning algorithms used in learning section 94 are simple regression algorithms,
It may be a decision tree model (random forest or gradient boosting, etc.), a deep learning algorithm (convolutional neural network). Appropriate machine learning algorithms or combinations of input variables Vi may also be selected depending on the type or characteristics of the ink used. Also, the learning unit 94 may update the flow rate prediction model 931 by performing machine learning periodically or based on an instruction input from the user. Accordingly, deterioration of the flow rate prediction model 931 can be suppressed by updating the flow rate prediction model 931 .

When using the print pattern, the flow rate prediction unit 93 may generate the ink discharge amount (consumption amount) as intermediate data from the density information of each color indicated by the image data. The flow rate prediction model 931 may be configured to output the flow rate Fp1 using this intermediate data as an input variable Vi. Also, the flow rate prediction model 931 may be constructed so as to output the flow rate Fp1 with the image data as the input variable Vi. In this case, the flow prediction model 931 may be constructed by a supervised deep learning algorithm.

In addition, when using the liquid level height displacement measured by the liquid level sensor 381, the flow rate prediction model 931 calculates the inclination (differential value) of how the ink decreases from the liquid level height displacement measured during printing. , and the slope may be used as the input variable Vi.

When constructing the flow rate prediction model 931, the ink characteristics (viscosity, specific heat, thermal conductivity, etc.) may be included in the model in order to make the model versatile. In this case, one model can handle inks with various characteristics. Also, the model may include information about the device configuration (for example, the volume inside the ejection head 21). In this case, one model can correspond to various device configurations.

A temperature difference DT1 (=Ttg−Te1) between the target temperature Ttg and the tank internal temperature Te1 measured by the tank internal temperature sensor 361 is input to the first heater control unit 91 . Based on the temperature difference DT1 and the flow rate Fp1 output by the flow rate prediction section 93, the first heater control section 91 sets the heater command value CV1 so that the heater section 351 is warmed in advance in preparation for the temperature drop due to the flow rate fluctuation. to output

The first heater control section 91 may determine the heater command value CV1 based on a lookup table that defines the relationship between the flow rate Fp1 and the temperature difference DT1 and the heater command value CV1. Alternatively, the first heater control unit 91 may determine the heater command value CV1 using an inference model that inputs the flow rate Fp1 and the temperature difference DT1 and outputs the heater command value CV1. This inference model may be constructed using a machine learning algorithm similar to the flow prediction model 931 described above.

As shown in FIG. 3, the first heater control section 91 may output the heater command value CV1 based on the outside air temperature Te2 measured by the outside air temperature sensor 39. The tank internal temperature Te1 is strongly influenced by the temperature outside the ink tank 311 . Therefore, the ink can be appropriately heated by determining the heater command value CV1 in consideration of the outside air temperature Te2.

As shown in FIG. 3, the first heater control section 91 may output the heater command value CV1 based on the flow rate Fc1 measured by the flow meter 341. In this case, the first heater control unit 91 can determine the heater command value CV1 according to fluctuations in the flow rate that can occur after the lapse of a predetermined time from the current time, so that the ink can be heated appropriately.

The first heater control unit 91 may output the heater command value CV1 based on the thermal properties of the ink (specific heat, thermal conductivity, etc.). The thermal properties of the ink are provided to the first heater controller 91 based on user input. Thermal properties of the ink can play a large role in the amount of heat to be applied. Therefore, the ink can be appropriately heated by determining the heater command value CV1 in consideration of the thermal characteristics of the ink.

The first heater control unit 91 may output a negative heater command value VC1 when the predicted flow rate Fp1 decreases. In this case, since the value of the heater command value VC2 given to the heater section 351 can be reduced, the heating amount of the heater section 351 can be reduced (or set to zero) according to the predicted decrease in the flow rate Fp1. can be done. As a result, it is possible to prevent the ink from being heated more than necessary when the flow rate of the ink to the ejection heads 21 to 24 is reduced.

The second heater control unit 92 executes feedback (FB) control. FB control is preferably PID control. However, FB control may be PI control. The second heater control unit 92 sets the heater command value CV2 to the heater unit 351 based on the difference value DT2 (=Ttg−Te3) between the target temperature Ttg and the ink temperature Te3 at the outlet position measured by the outlet temperature sensor 371. output to The second heater control unit 92 determines the heater command value CV2 so that the ink temperature Te3 at the outlet position approaches the target temperature Ttg.

FIG. 4 is a diagram showing temperature fluctuations of the ink at the exit position of the heater section 351. FIG. In FIG. 4 , the horizontal axis indicates time, and the vertical axis indicates temperature measured by the outlet temperature sensor 371 . In FIG. 4, a waveform G11 indicates a temperature change when only the FB control by the second heater control section 92 is performed. A waveform G12 indicates a temperature change when FF control is performed by the first heater control unit 91 in addition to FB control. A waveform G2 in FIG. 4 indicates the fluctuation of the ink flow rate Fc1 measured by the flow meter 341. FIG.

As shown in FIG. 4, when the flow rate Fc1 increases, the temperature Te3 rises after the temperature Te3 momentarily drops in both waveforms G11 and G12. However, as shown in the waveform G11, in the case of only the FB control, the heating of the heater section 351 is delayed, so the temperature fluctuation range (difference between the maximum temperature and the minimum temperature during one cycle of heating ON/OFF) increases (specifically, is about 1.4° C.). On the other hand, as shown by waveform G12, by adding FF control to FB control, the temperature fluctuation range becomes smaller than in the case of only FB control (specifically, about 0.8° C.). Also, the waveform G11 is out of the allowable temperature range (here, 32° C.±0.5° C.), while the waveform G12 is almost within the allowable temperature range. By performing FF control based on the predicted flow rate Fp1 in this way, the temperature fluctuation range can be reduced.

FIG. 5 is a diagram showing the correspondence relationship between the temperature of the ink at the inlet position of the heater section 351 and the width of temperature fluctuation. In FIG. 5, the horizontal axis indicates the temperature of the ink at the inlet position (that is, the temperature of the ink before being heated by the heater section 351; hereinafter referred to as "heater inlet position temperature"), and the vertical axis indicates the temperature fluctuation range. indicates In FIG. 5, the graph G31 shows the correspondence when only the FB control by the second heater control unit 92 is performed, and the graph G32 shows the correspondence when the FF control is performed by the first heater control unit 91 in addition to the FB control. Show relationship.

As shown in graph G31, in the case of only FB control, in order to achieve the target temperature fluctuation width (eg, 1° C.), the heater inlet position temperature is set to a relatively high temperature (eg, approximately 23° C. or higher). There is a need. On the other hand, as shown in graph G32, by adding FF control to FB control, the target temperature fluctuation range can be achieved at a relatively low heater inlet temperature (for example, about 16° C. or higher). That is, by combining the FF control by the first heater control section 91 and the FB control by the second heater control section 92, the condition of the heater inlet position temperature can be greatly relaxed. As a result, the temperature control system can be simplified by omitting a heater for heating the ink in the ink tank 311 . However, providing a heater in the ink tank 311 is not prevented.

<2. Variation>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

For example, in the above embodiment, ink is supplied in one direction from the supply unit 30 to each of the ejection heads 21-24. However, a circulation path for circulating ink may be provided between the supply section 30 and each of the ejection heads 21-24. Further, a circulation path may be provided for circulating the ink within the ejection heads 21 to 24 . Alternatively, a heater section for heating the ink may be provided on the circulation path, and the heater section may be controlled by the first heater control section 91 and the second heater control section 92 .

Although the present invention has been described in detail, the above description is, in all aspects, exemplary and the present invention is not limited thereto. It is understood that numerous variations not illustrated can be envisioned without departing from the scope of the invention. Each configuration described in each of the above embodiments and modifications can be appropriately combined or omitted as long as they do not contradict each other.

1 printing device 9 control unit 21-24 ejection head 39 outside temperature sensor 90 ejection control unit 91 first heater control unit 92 second heater control unit 93 flow rate prediction unit 95 motor drive unit 311 ink tank 321 pipe 331 pump 341 flow meter 351 Heater part 361 In-tank temperature sensor 371 Outlet temperature sensor 931 Flow rate prediction model W Base material

Claims

A printing device,
an ejection head for ejecting ink onto the surface of a substrate;
an ink tank capable of storing the ink;
an ink supply unit that supplies the ink from the ink tank to the ejection head;
a heater unit that heats the ink flowing from the ink tank to the ejection head;
a flow rate prediction unit that predicts the flow rate of ink flowing from the ink tank to the ejection head after a predetermined time from the current time;
a first heater control unit that controls the heater unit based on the flow rate predicted by the flow rate prediction unit;
a first temperature measurement unit that measures the temperature of ink flowing from the heater unit to the ejection head;
a second heater control unit that controls the heater unit based on the difference between the temperature measured by the first temperature measurement unit and a preset target temperature;
A printing device.
The printing device according to claim 1, wherein
The printing apparatus, wherein the flow rate prediction unit predicts the flow rate based on ejection information indicating the amount of ink ejected from the ejection head.
The printing device according to claim 2,
an ejection control unit that controls the ejection head based on print data;
further comprising
A printing apparatus, wherein the ejection information includes the print data.
The printing apparatus according to any one of claims 1 to 3,
a second temperature measuring unit that measures the temperature of the ink in the ink tank;
further comprising
The printing apparatus, wherein the first heater control section controls the heater section based on a difference between the temperature measured by the second temperature measurement section and a preset target temperature.
The printing apparatus according to any one of claims 1 to 4,
a third temperature measuring unit that measures the temperature outside the ink tank;
further comprising
The printing apparatus, wherein the first heater control section controls the heater section based on the temperature measured by the third temperature measurement section.
The printing apparatus according to any one of claims 1 to 5,
a flow rate measurement unit that measures the flow rate of ink supplied from the ink tank to the ejection head;
further comprising
The printing apparatus, wherein the first heater control section controls the heater section based on the flow rate measured by the flow rate measurement section.
A printing method comprising:
a) a prediction step of predicting the flow rate of ink flowing from the ink tank to the ejection head after a predetermined time from the current time;
b) heating the ink flowing from the ink tank to the ejection head with a heater;
c) measuring the temperature of the ink flowing from the heater section to the ejection head;
Said step b) is
b-1) controlling the heater unit based on the flow rate predicted by the step a);
b-2) controlling the heater unit based on the difference between the temperature measured in c) and a preset target temperature;
printing methods, including;