Recording device and control method of recording device

Abstract

To provide a recording device for circulating ink on a circulation path which can determine whether or not a circulation state of the ink is normal.SOLUTION: A recording device includes a recording head which includes a discharge port for discharging ink, and a pressure chamber for filling ink discharged from the discharge port, and discharges the ink from the discharge port and performs recording operation, circulation means for performing circulation operation to circulate the ink on a circulation path including the pressure chamber when the recording operation is performed, and a control part, where the control part acquires temperature information that is information on a temperature of the recording head, in a state in which the circulation means performs the circulation operation, and determines the circulation state of the ink on the circulation path, on the basis of the information on the temperature.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus that circulates ink through a printhead and a circulation path that includes the printhead, and a method for controlling the printing apparatus. [Background technology]

[0002] In inkjet printers, the evaporation of volatile components in the ink from the nozzles of the print head causes an increase in the viscosity of the ink near the nozzles. One known solution to this problem is to circulate the ink supplied to the print head within a circulation path. However, because the ink is circulated, fresh ink is constantly being supplied to the nozzles, which causes moisture to evaporate from the nozzles and gradually increases the ink concentration throughout the circulation path.

[0003] In order to prevent the ink concentration in the entire circulation path from increasing and the volatile components in the ink near the ejection ports from evaporating, Patent Document 1 describes a technology that stops the ink circulation when printing is completed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-121784 Summary of the Invention [Problem to be solved by the invention]

[0005] A print head may be equipped with a heater to raise the print head temperature and maintain it at a high level. The print head may also be equipped with a heat-generating element to cause the ink to bubble using thermal energy. Therefore, if printing is performed for a long period of time, the temperature of the print head may not drop completely even when the print head heating operation is stopped due to the heat accumulated in the print head components caused by the head heating heater and heat-generating element, and the temperature near the ejection ports may remain high.

[0006] Normally, when a print start signal is received, the circulation pump starts to drive and ink circulates, but even if the circulation pump is operating normally electrically, it is possible that ink may not actually circulate properly near the nozzles due to clogging of the ejection ports or nearby foreign matter or bubbles, etc. If such a state of ink circulation near the nozzles is left as it is, the ink near the ejection ports will thicken, which can affect ejection.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make it possible to determine whether the ink circulation state is normal in a recording device in which ink circulates through a circulation path. [Means for solving the problem]

[0008] The present invention employs the following configuration: a print head including a discharge port for discharging ink and a pressure chamber filled with ink to be discharged from the discharge port, the print head performing a printing operation by discharging ink from the discharge port; a circulation unit that performs a circulation operation for circulating ink in a circulation path including the pressure chamber when the recording operation is performed; A control unit; A recording device having: The control unit While the circulation unit is performing the circulation operation, temperature information is acquired, which is information regarding the temperature of the print head. A circulation state of the ink in the circulation path is determined based on the information about the temperature. The recording device is characterized by the above. [Effects of the Invention]

[0009] According to the present invention, in a recording apparatus in which ink circulates through a circulation path, it is possible to determine whether the ink circulation state is normal. [Brief explanation of the drawings]

[0010] [Figure 1] Perspective view of an inkjet recording apparatus [Figure 2] FIG. 1 is a perspective view schematically illustrating a recording head; [Figure 3] FIG. 2 is a diagram illustrating the configuration of a print head and a buffer tank. [Figure 4] A diagram showing the configuration of ejection ports and flow paths within the printing element substrate, and the flow of ink. [Figure 5] A perspective view of the recording element substrate when viewed from a direction perpendicular to the XY plane [Figure 6] (a) is an enlarged view of a part of the recording element substrate; (b) is a cross-sectional view taken along the cross-sectional line. [Figure 7] Block diagram of a control system installed in an inkjet recording apparatus [Figure 8] Flowchart of the circulation detection operation of the first embodiment [Figure 9] Image of print head temperature change after printing operation [Figure 10] (a) to (c) Tables for determining the predetermined value α in the first embodiment [Figure 11] Flowchart of a circulation detection operation in a modified example [Figure 12] Flowchart of the loop detection operation of the second embodiment [Figure 13] Table for determining the predetermined value α in the second embodiment [Figure 14] Flowchart of the circulation detection operation of the third embodiment [Figure 15] Flowchart of the circulation detection operation of the fourth embodiment DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the components described in these embodiments are not intended to limit the scope of the present invention. Furthermore, the materials, shapes, and the like of components described once in the following description will remain the same in subsequent descriptions unless otherwise specified. Well-known or publicly known technologies in the relevant technical field can be applied to configurations and processes not specifically illustrated or described. Furthermore, the present invention is not limited to these embodiments, and not all of the combinations of features described in these embodiments are necessarily essential to the solution of the present invention.

[0012] An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the appearance of an inkjet printing apparatus 50 (hereinafter also referred to as a printer) according to an embodiment. The printing apparatus 50 is a serial scan type printer that prints an image by scanning a print head in a direction (X direction) perpendicular to the conveyance direction (Y direction) of the printing medium P. The following description will be given taking as an example a printing apparatus 50 equipped with such a serial type print head. However, the present invention is not limited to this, and is applicable to printing element substrates, print heads, or printing apparatuses in general that may encounter the problems that the present invention is intended to solve. For example, the present invention is also applicable to line head type print heads.

[0013] The configuration of the recording device 50 and its operation during recording will be outlined with reference to FIG. The recording medium P is held by a spool 6. First, the recording medium P is transported in the Y direction from the spool 6 by a transport roller (not shown) driven by a transport motor via a gear. Meanwhile, at a predetermined transport position, a carriage motor (not shown) causes the carriage unit 2 to scan along a guide shaft 8 extending in the X direction. The method of transmitting the driving force from the carriage motor to the carriage unit 2 is not important. For example, a carriage belt may be used, or a combination of a lead screw that is rotationally driven by the carriage motor and extends in the X direction and an engagement portion that is provided on the carriage unit 2 and engages with a groove in the lead screw may be used.

[0014] During this scanning process, liquid such as ink is ejected from the ejection ports of a print head (described later) attached to the carriage unit 2, thereby recording an image having a certain bandwidth corresponding to the array range of the ejection ports. The timing of liquid ejection is controlled based on a position signal obtained by an encoder 7. In the ejection operation of this embodiment, the scanning speed is 40 inches per second, and the resolution is 600 dpi (1 / 600 inch). After recording is completed for one bandwidth, the print medium P is transported, and then recording is completed for the next bandwidth. By repeating this process, the desired image is formed on the print medium P. Note that an image may be recorded in a unit area on the print medium P in one scan (so-called one-pass recording), or may be recorded in multiple scans (so-called multi-pass recording).

[0015] The fed recording medium P is sandwiched and transported between a paper feed roller and a pinch roller (not shown) and guided to the recording position (main scanning area of the recording head) on the platen 4. Normally, the face of the recording head is capped when in a resting state, so prior to recording, the cap is opened to make the recording head or carriage unit 2 ready for scanning. After that, once data for one scan has been accumulated in the buffer, the carriage motor is used to scan the carriage unit 2, and recording is performed as described above.

[0016] The print head is attached to one end of a flexible wiring board 190 for supplying drive pulses for ejection drive, head temperature control signals, etc. The other end of the flexible wiring board 190 is connected to a control unit equipped with a control circuit such as a CPU that controls the printer. Also, a thermistor (not shown) is provided near the control unit as a temperature sensor for detecting the ambient temperature inside the inkjet printing apparatus.

[0017] FIG. 2 is a perspective view schematically showing a recording head 9 according to this embodiment. The recording head 9 is formed with a joint portion 25, to which an ink supply tube is connected. Ink is pressurized from an ink tank (not shown), reaches the recording head 9 through the supply tube, passes through a filter, and then flows into the flow path. Note that the recording device 50 according to this embodiment will be described taking as an example a configuration in which ink is circulated within the recording head 9, but the ink circulation configuration is not particularly limited. The ink circulation path may include an area outside the recording head 9.

[0018] Two recording element substrates 10a, 10b made of semiconductor or the like are attached to the ejection port formation surface, which is the surface of the recording head 9 facing the recording medium P. Each of the recording element substrates 10a, 10b has ejection port arrays 11-18 formed along the Y direction, which is orthogonal to the X direction, and is configured to be able to eject ink of multiple ink types. In this embodiment, it is configured to be able to eject ink of multiple colors.

[0019] As will be described later, a recording element array is formed at a position in the recording element substrates 10a and 10b opposite each of the ejection port arrays 11 to 18. The recording element substrates 10a and 10b are fixed with an adhesive to a support member 300 made of alumina, resin, or the like. Furthermore, the recording element substrates 10a and 10b are electrically connected to an electric wiring member 600 provided with wiring, and the electric wiring Communication with the control unit is performed via the wire member 600.

[0020] 3 is a diagram showing a schematic configuration of the print head 9 and buffer tank 401. A method of supplying ink to the print head 9 and buffer tank 401 and a method of circulating ink within the ejection ports in this embodiment will be described. While a schematic diagram of a flow path for one color is shown here, buffer tanks and flow paths for multiple colors may be provided in one print head, in which case multiple configurations similar to the one shown in the figure will exist. Furthermore, the print element substrates 10a and 10b will not be distinguished from each other and will be described as print element substrate 10.

[0021] The supply tube 301 is connected to the joint portion 25 of the print head through the inside of the carriage unit 2 and is in communication with a buffer tank 401. The supplied ink passes through a filter 405, passes through a flow path in the buffer tank, and reaches a first pressure control member 406. The first pressure control member 406 is connected to a second pressure control member 407 by two flow paths: a flow path including a valve 412 and a flow path via a pump 408.

[0022] Valves 411, 412 that open when a predetermined negative pressure is reached are disposed at the inlets of the first pressure control member 406 and the second pressure control member 407. The inlet of the first pressure control member 406 is provided in the flow path between it and the filter 405. The inlet of the second pressure control member 407 is provided in the flow path between it and the first pressure control member 406. The negative pressure at which valve 412 at the inlet of the second pressure control member 407 opens is set to be higher than the negative pressure at which valve 411 of the first pressure control member opens.

[0023] Ink flows into the recording element substrate 10 from the joint 25, passes through a first pressure control member 406, and reaches a common supply flow path 409 formed inside the recording head. The ink is then supplied from the common supply flow path 409 to individual supply flow paths (described later) of one or more ejection port arrays arranged inside the recording element substrate 10. Ink that is not ejected then passes near the ejection ports and flows into individual recovery flow paths (described later) inside the recording element substrate 10. The ink then passes through a common recovery flow path 410 formed inside the recording head 9 and is returned to the second pressure control member 407.

[0024] 4 is a diagram showing the configuration of ejection ports and flow paths formed in the recording element substrate 10, and the flow of ink. The recording element substrate 10 is configured such that an orifice plate 420 is laminated on one surface of a substrate 444, and a cover plate 440 is laminated on the other surface. An ejection port 132 is formed in the orifice plate 420. When ink is supplied to the flow path, it is maintained at a negative pressure such that a meniscus is formed on the ejection port surface.

[0025] Two flow paths, an inlet 421 and an outlet 422, are formed on both sides of the ejection port 132. In this embodiment, as shown in FIG. 4, one inlet 421 and one outlet 422 are arranged for every two ejection ports 132. The number of inlets 421 and outlets 422 is not particularly limited, and one inlet 421 and one outlet 422 may be provided for every ejection port 132, or one for every three or more ejection ports 132. The inlet 421 and the outlet 422 are connected to individual supply flow paths 431 and individual recovery flow paths 432, respectively, which are formed along the ejection port array direction. The individual supply flow paths 431 and individual recovery flow paths 432 are covered with a cover plate 440 and are connected to the common supply flow path 409 and the common recovery flow path 410 of the print head 9 via openings 441 in the cover plate 440. One or more openings 441 are provided for each individual supply flow path 431 and each individual recovery flow path 432. Furthermore, the number of openings 441 may be the same or different between the supply flow path and the recovery flow path.

[0026] (Configuration of the recording element substrate) FIG. 5 is a perspective view of the recording element substrate 10b when viewed from a direction perpendicular to the XY plane. 6A is a schematic plan view showing an enlarged portion of the recording element substrate 10b, and FIG. 6B is a schematic cross-sectional view taken along the cross-sectional line Xb-Xb in FIG. 6A.

[0027] In this embodiment, each of the ejection opening arrays 15 to 18 includes two arrays. These two arrays are arranged in the Y direction (arrangement direction) with each array being shifted by one dot at 1200 dpi (dots per inch) from the array facing each other. The ejection openings 13 in one array The number of outlets 132 in the two rows is 768, and a total of 1536 outlets 132 are provided in the two rows.

[0028] As shown in FIG. 6B, ejection elements 160 are provided at positions facing the ejection ports 132 in the Z direction. The ejection elements 160 are electrothermal transducers and will hereinafter also be referred to as main heaters. These ejection elements 160 are also arranged in the Y direction to follow the arrangement of the ejection ports 132. In this embodiment, 1200 dpi corresponds to approximately 0.02 mm. By applying a drive pulse to these ejection elements 160, thermal energy for ejecting ink from the ejection ports can be generated. Note that the ejection elements 160 are not limited to electrothermal transducers and may be, for example, piezoelectric elements. Hereinafter, an operational unit for ink ejection, including a pair of an ejection port 132 and an ejection element 160, will also be referred to as a "printing element."

[0029] For simplicity in the following explanation, of the 1,536 ejection ports 132 and ejection elements 160 included in a certain ejection port array, the printing element including the pair of ejection port 132 and ejection element 160 located most downstream in the Y direction will be collectively referred to as printing element No. 0. Furthermore, the pair of ejection port 132 and ejection element 160 located one position upstream of printing element No. 0 in the Y direction will be referred to as printing element No. 1. Hereinafter, the printing element Nos. will be defined in the same way, and the pair of ejection port 132 and ejection element 160 located most upstream in the Y direction will be collectively referred to as printing element No. 1,535.

[0030] Here, a plurality of temperature detection elements S (S1 to S9) are formed on the recording element substrate 10b and are evenly arranged on the recording element substrate 10b as temperature sensors for detecting the temperature of ink in the vicinity of the ejection elements 160. The temperature detection elements S are shown in a see-through manner in Figure 5. However, the locations where the temperature detection elements S are provided are not limited to this, as long as the ink temperature can be measured.

[0031] In this embodiment, the temperature of the ink inside the ejection port near the temperature detection element S is approximately the same as the temperature of the recording element substrate 10b at the position where the temperature detection element S is provided. Therefore, the temperature of the recording element substrate 10b is treated as the temperature of the ink.

[0032] In addition to the ejection elements 160, the recording element substrate 10b is also provided with heating elements 19a and 19b capable of heating the recording element substrate. Immediately before starting a recording operation, the control unit uses the heating elements 19a and 19b to perform temperature adjustment control to heat the ink to a constant temperature. This suppresses changes in the viscosity of the ink in the recording head 9, and makes it possible to maintain a constant viscosity regardless of the ambient temperature.

[0033] (Nozzle circulation configuration) In the recording element substrate 10b, pressure chambers 23 filled with ink are provided near the joint between the orifice plate 420 and the substrate 444. Ejection ports 132 are provided so as to penetrate from the pressure chambers 23 through the orifice plate 420. The above-mentioned ejection elements 160 are provided at positions in the pressure chambers 23 facing the ejection ports 132. In the recording element substrate 10b, the substrate 444 is also formed with individual supply flow paths 431 connected to the common supply flow path 409 and individual recovery flow paths 432 connected to the common recovery flow path 410, for each ejection port 132.

[0034] With the above-described configuration, the negative pressure on the recording element substrate 10b is relatively weak (the absolute value of the pressure is A flow is generated in which ink flows in from the common supply flow path 409, which has a relatively strong negative pressure (high absolute pressure value), and then flows out to the common recovery flow path 410, which has a relatively strong negative pressure (low absolute pressure value). More specifically, the ink flows in the order of the common supply flow path 409 → individual supply flow path 431 → pressure chamber 23 → individual recovery flow path 432 → common recovery flow path 410.

[0035] Here, when the ink in the pressure chamber 23 is ejected by driving the ejection element 160, part of the ink moving from the common supply flow path 409 to the common recovery flow path 410 is ejected from the ejection port 132 and discharged to the outside of the recording head 9. On the other hand, the ink that is not ejected from the ejection port 132 is recovered to the second pressure control member 407 via the common recovery flow path 410.

[0036] When the print head is filled with ink at an appropriate negative pressure so that a meniscus is maintained on the ejection port surface, the valve 411 at the inlet of the first pressure control member 406 is closed, and ink does not flow into the first pressure control member 406. However, if a strong negative pressure is applied to the ejection port by the suction operation of the cap of the recovery processing device, or if ink is ejected from the ejection port, and the negative pressure of the first pressure control member 406 increases, the valve 411 at the inlet opens, and ink flows into the first pressure control member.

[0037] As shown in FIG. 3 , the first pressure control member 406 and the second pressure control member 407 are connected to a pump 408. When the pump 408 is driven, ink is transferred from the second pressure control member 407 to the first pressure control member 406 via the pump 408. This increases the negative pressure in the second pressure control member 407, causing the valve 412 of the second pressure control member 407 to open, causing the ink to flow back from the first pressure control member 406 to the second pressure control member 407. At this time, a pressure difference is generated between the first pressure control member 406 and the second pressure control member 407, so that the ink passes through the flow path from the first pressure control member 406 to the common supply flow path 409, the cover plate opening 441, the individual supply flow path 431 of each ejection port array, and the inlet 421 in this order. At this time, some of the ink flows into the ejection ports 132.

[0038] The ink then passes through the flow path from the ejection port 132 to the outlet 422, the individual recovery flow path 432, the cover plate opening 441, and the common recovery flow path 410, in that order, before returning to the second pressure control member 407. The pump flow rate, the pressure loss in the flow path between the first and second pressure control members, and the opening and closing force of the inlet valve are adjusted so that the negative pressure inside the ejection port and the ink flow velocity are within a range that allows a meniscus to be maintained. The above configuration and control cause ink to move near the ejection port 132 in response to the drive of the pump 408. This suppresses an increase in ink viscosity due to drying inside the ejection port during printing, preventing deterioration of the ink ejection characteristics. While the printing element substrate 10b has been described in detail here, the printing element substrate 10a also has a similar configuration.

[0039] <Control system configuration> FIG. 7 is a block diagram showing the configuration of a control system installed in the recording apparatus 50 of this embodiment. The main control unit 100 includes a CPU 101, a ROM 102, a RAM 103, an input / output port 104, and an EEPROM 122. The CPU 101 performs processing operations such as calculation, control, determination, and setting. The ROM 102 functions as a memory for storing control programs to be executed by the CPU 101. The RAM 103 is used as a buffer for storing binary recording data indicating whether or not ink is ejected, and as a work area for processing by the CPU 101. The RAM 103 can also be used as a storage means for storing the amount of ink in the main tank before and after a recording operation, the free space in the sub-tank, and the like. The input / output port 104 inputs and outputs signals. The EEPROM 122 is used as a non-volatile memory.

[0040] The input / output port 104 is connected to a transport motor (LF motor) 113 for driving the transport roller, a carriage motor (CR motor) 114, the recording head 9, a recovery processing device 120, and other drives. Drive circuits 105, 106, 107, and 108 are connected to the input / output port 104. Each of these drive circuits 105, 106, 107, and 108 is controlled by a main control unit 100. The input / output port 104 is connected to various sensors, such as temperature detection elements S1 to S9, which are diode sensors that detect the temperature of the printhead 9, an encoder sensor 111 fixed to the carriage unit 2, and a thermistor 121 that detects the atmospheric temperature (environmental temperature) inside the printing device 50. The main control unit 100 is also connected to a host computer 115 via an interface circuit 110.

[0041] The drive circuit 107, which functions as a signal transmitter for the printhead, transmits and receives drive pulses to be applied as well as print data for printing, which are transferred via the flexible wiring board 190 described above.

[0042] The recovery process counter 116 counts the number of times the ejection elements 160 are driven in association with the recovery process, in which the recovery processing device 120 forcibly discharges ink from the print head 9. The preliminary ejection counter 117 counts the number of times the ejection elements 160 are driven in association with preliminary ejection, which is performed before printing starts, at the end of printing, or during printing. The borderless ink counter 118 counts the number of times the ejection elements 160 are driven when ejecting ink outside the print medium area when performing borderless printing. The ejection dot counter 119 counts the number of times the ejection elements 160 are driven during printing. The sum of the count values calculated by these counters 116 to 119 is stored in the EEPROM 122 as the cumulative number of times the ejection elements 160 in each ejection element array have been driven since the print head 9 was installed in the printing device 50. In this embodiment, the cumulative number of times the ejection elements 160 have been driven is calculated for each ejection element array. The EEPROM 122 can also store various information in addition to the cumulative number of times the ejection elements have been driven.

[0043] First Embodiment The circulation detection operation, which is a feature of the first embodiment, will now be described. Figure 8 shows a flowchart of a series of circulation detection operations performed by the main control unit 100. This flowchart starts after the recording operation by the recording head 9 has finished. As mentioned above, the circulation operation is started at the time of the recording operation in order to suppress an increase in ink viscosity due to drying inside the ejection ports and to prevent deterioration of the ink ejection characteristics. Therefore, the circulation operation is already being performed when this flowchart starts.

[0044] In step S801, the main control unit 100 stops driving the heating elements 19 for heating the recording element substrate 10, and stops temperature adjustment control of the recording head 9.

[0045] In step S802, the main control unit 100 brings a cap member (not shown) into contact with the ejection port surface of the print head 9 to close the cap. After the printing operation is completed, the processes of S801 and S802 are performed in parallel, and when the processes of S801 and S802 are completed, the process proceeds to S803.

[0046] In step S803, the main control unit 100 acquires information (temperature information) relating to the temperature of the print head 9 from the plurality of temperature detection elements S1 to S9 in the print element substrate. Hereinafter, T1 will be referred to as the first head temperature. This step corresponds to acquiring first temperature information at a first timing. In this embodiment, the maximum value of the temperatures detected by the temperature detection elements S1 to S9 is determined as the temperature of the print head 9. Note that the method for determining the temperature of the print head 9 is not limited to the above method. The average value of the detection values of the plurality of temperature detection elements S1 to S9 may also be used as the temperature of the print head 9. Alternatively, the temperature of the print head 9 may be determined from the temperatures of other components constituting the print head 9. Furthermore, the temperature detection elements arranged around the opening may be selected from the plurality of temperature detection elements S1 to S9 in the print element substrate to determine the temperature of the print head 9. This is because the flow path resistance is low near the opening 441, making it easy for ink to flow. This is because it is easy to read the temperature change due to the circulation state. Note that in S803, the environmental temperature, recording time, and recording duty ratio may also be acquired. Control using this information will be described later.

[0047] In step S804, the main control unit 100 waits for a predetermined time. "Waiting" means maintaining a state in which ink circulation is controlled without performing a printing operation. In other words, in this example, ink circulation control is continued for 30 seconds to observe changes in the temperature of the print head. Note that the wait time of 30 seconds is an example and is not limited to this.

[0048] Here, we will discuss temperature changes when circulation is operating normally and when it is not. Figure 7 is an image diagram of the print head temperature change transition after the end of a printing operation in this embodiment. The horizontal axis represents elapsed time, and the vertical axis represents print head temperature. The solid line is a graph when circulation is operating normally, and the dotted line is a graph when circulation is not operating (non-circulation). As shown in Figure 9, the slope of the temperature drop is gentle when circulation is operating normally, and the slope of the temperature drop is steep when circulation is not operating.

[0049] The reason for the relationship shown in Figure 9 is that, in this embodiment, ink is circulated within the print head. That is, because temperature modulation control and circulation are performed for the printing operation, the ink throughout the print head, not just near the ejection orifices 132, is warmed after printing is completed. Normally, when temperature modulation control is stopped while circulation is stopped, the ink near the ejection orifices 132 quickly cools. On the other hand, when circulation is operating, the cooled ink quickly flows away from the print element substrate where the temperature detection elements S1 to S9 are located and moves toward the top of the print head, and the ink, still at a high temperature, flows near the temperature detection elements. Therefore, in this embodiment, the temperature drop slope is gentler when circulation is operating normally. However, as mentioned above, the circulation mode is not limited to this embodiment, and the relationship between the circulation state and temperature change may vary depending on the circulation mode.

[0050] In step S805, the main controller 100 acquires the print head temperature again after a predetermined time has elapsed and sets this as the second print head temperature T2. This step corresponds to acquiring second temperature information at a second timing that is later than the first timing. Next, in step S806, the main controller 100 determines whether the difference (T1-T2) between the first print head temperature T1 and the second print head temperature T2 is less than the threshold value α. If the difference is less than the threshold value (S806=YES), it is determined that circulation is normal, and the process proceeds to step S809, where the circulation process is stopped and the circulation detection operation is terminated. On the other hand, if the difference is equal to or greater than the threshold value (S806=NO), it is determined that the circulation state is abnormal, and the process proceeds to step S807, where the circulation process is stopped, and then to step S808, where a print head recovery process is attempted and the circulation detection operation is terminated. In step S808, normal recovery processing may be performed, or based on the detection result that the circulation state is not normal, a more effective recovery processing than normal may be performed to clear the nozzle blockage, or a notification that the circulation is abnormal (notification to the user or notification requesting the dispatch of a service technician (service call)) may be performed.

[0051] Here, the threshold value α, which is the temperature difference for determining the circulation state, may be a predetermined value or may be determined based on various information. Examples of the various information include the ambient temperature, recording time, and recording duty ratio, which are acquired at the timing of S803. The ambient temperature is temperature information acquired by the thermistor 121. The recording time is, for example, the recording time (operating time) of the immediately preceding recording operation, which is acquired by referring to the operation record of the recording device 50. The recording duty ratio is a value calculated from the printing rate in the image data, and may be calculated by analyzing the image data or from the count value of the ejected dot counter 119. The printing rate or ink amount of the recorded image may be used instead of the duty ratio.

[0052] 10(a) to 10(c) show tables for determining the threshold value α based on the ambient temperature, the previous recording time, and the duty ratio of the image to be recorded. Note that the values in each table are merely examples and are not limiting.

[0053] In Figure 10(a), the threshold value α is determined according to the ambient temperature. The lower the ambient temperature, the faster the head temperature drops. Therefore, the lower the ambient temperature, the larger the threshold value α. In Figure 10(b), the threshold value α is determined according to the time of the previous recording. The longer the recording time, the more the effect of temperature accumulation remains, and the slower the head temperature drops. Therefore, the longer the recording time, the smaller the threshold value α. In Figure 10(c), the threshold value α is determined according to the duty ratio of the image to be recorded. The higher the duty ratio, the higher the temperature reached when the recording head heats up, and the slower the head temperature drops accordingly. Therefore, the higher the duty ratio, the smaller the threshold value α.

[0054] Note that any one of Figures 10(a) to 10(c) may be used, or multiple tables may be used. When multiple tables are used, the value of the threshold α may differ for each table. In that case, the largest value may be adopted. Alternatively, when multiple values are used, a mathematical formula including each value may be used instead of a table. In that case, a mathematical formula including the environmental temperature, recording time, and duty ratio as parameters is stored in ROM 102 in advance.

[0055] (Variation) FIG. 11 is a flowchart according to a modified example of this embodiment. While FIG. 8 judges the temperature difference between the print heads, FIG. 11 judges the temperature difference based on the relative amount of change in temperature. Explanations of steps that are the same as those in FIG. 8 will be omitted. In step S1106, the main control unit 100 divides the difference between the first head temperature T1 immediately after temperature modulation control and the second head temperature T2 after a 30-second wait by the time. This allows calculation of the coefficient β [°C / sec], which indicates the temperature change per unit time (β=(T2-T1) / 30 [°C / sec]).

[0056] In step S1107, the main control unit 100 compares the temperature relative change coefficient β with a predetermined value γ to detect the circulation state. That is, if the temperature relative change coefficient β is less than the predetermined value γ (S1107=YES), it means that the temperature change per unit time is relatively small, and it is determined that circulation is normal, and circulation is stopped and detection is terminated as in S809 of Figure 8. On the other hand, if the temperature relative change coefficient β is equal to or greater than the predetermined value γ (S1107=NO), the process proceeds to step S1108 to stop the circulation process, and then to step S1109 to perform head recovery process.

[0057] As described above, according to this embodiment, the circulation state of the nozzles can be detected by the temperature change of the print head after the end of a printing operation. If it is determined that the circulation state is not normal, recovery processing, an error notification, a service call, etc. can be performed, and ultimately, it becomes possible to prevent the ink near the ejection ports from thickening and causing ejection problems.

[0058] Second Embodiment Next, the second embodiment will be described, focusing on the differences from the first embodiment. In the first embodiment, the circulation state is detected after the printing operation, but in this embodiment, the same detection is performed before the printing operation starts.

[0059] FIG. 12 shows a flowchart of a series of circulation detection operations performed by the main control unit 100. This flowchart starts after the main control unit 100 receives a print start signal. Unless otherwise specified, the configuration and processing are the same as in the first embodiment. In step S1201, the main control unit 100 starts circulation of the print head. In step S1202, the main control unit 100 sets the cap to an open state. In step S1203, the main control unit 100 acquires the first head temperature T1 of the print head 9. Note that this The ambient temperature may be acquired.

[0060] In step S1204, the main control unit 100 starts temperature adjustment control of the print head 9. In step S1205, the main control unit 100 waits for a predetermined time. The length of time is not particularly limited, but may be, for example, one second. In step S1206, the main control unit 100 again acquires the second head temperature T2 after the predetermined time.

[0061] In step S1207, the main control unit 100 calculates the difference between the first head temperature T1 and the second head temperature T2 and compares it with a predetermined threshold value α (T2 - T1 < α?). If the difference is less than the threshold value α (S1207 = YES), it is determined that circulation is normal and the printing operation begins. If printing has not yet started, the circulation status is detected from the temperature rise and change until the target temperature is reached through temperature adjustment control within a predetermined time. If circulation is normal, ink that is still cold flows near the temperature detection element one after another, and as in the first embodiment, it is determined that circulation is normal based on the gradual temperature change. On the other hand, if the temperature difference is greater than or equal to the threshold value (S1207 = NO), it is determined that the circulation status is abnormal, and the flow proceeds to S1208, where the circulation process is stopped and the circulation detection operation is terminated by attempting print head recovery processing or the like.

[0062] The threshold value α for determining the circulation state may be a predetermined value stored in advance in ROM 102. Furthermore, if the ambient temperature is acquired by the thermistor 121 in S1203, the threshold value α may be determined based on the acquired ambient temperature by referring to a table such as that shown in FIG. 13. Note that in this embodiment, since detection is performed before the start of printing, the immediately preceding printing time and the duty ratio of the image to be printed are not used. Since the rate of head temperature rise slows as the ambient temperature decreases, the threshold value α in the table of FIG. 13 is set to a smaller value as the ambient temperature decreases.

[0063] <Third embodiment> Next, a third embodiment will be described, focusing on differences from the first and second embodiments. In this embodiment, circulation state detection control is not performed if the non-printing time since the end of the previous printing operation does not exceed a predetermined time. In this embodiment, the influence of temperature accumulation due to the previous printing operation can be eliminated, and false detection can be prevented.

[0064] 14 is a flowchart showing the details of the processing performed by the main control unit 100 in this embodiment. Portions not specifically mentioned have the same configuration and processing as those in the first and second embodiments.

[0065] In step S1401, if the non-recording time since the previous recording is longer than a predetermined time (which may be, but is not limited to, 20 minutes) (S1401=YES), the main control unit 100 proceeds to S1402 and S1403 and performs circulation state detection control. The contents of the circulation state detection control are the same as those in the first embodiment. On the other hand, if the non-recording time is less than the predetermined time (S1401=NO), the control ends.

[0066] According to this embodiment, it is possible to avoid erroneous detection due to determining the circulation state before the predetermined time has elapsed. Note that although Fig. 14 has been described with reference to an example of determining whether or not the circulation state detection control is necessary as described in the first embodiment, it can also be applied to the circulation state detection control before the start of a printing operation as described in the second embodiment.

[0067] <Fourth embodiment> Next, the fourth embodiment will be described, focusing on the differences from the first to third embodiments. Note that steps not specifically described can be executed in the same manner as in the second embodiment. In this embodiment, the circulation state detection control is performed after the recovery process has been performed, rather than before or after the printing operation. In this embodiment, the recovery process discharges ink near the ejection ports and replaces it with fresh, cool ink from the ink tank. As a result, the influence of temperature accumulation can be sufficiently eliminated and false detection can be prevented.

[0068] FIG. 15 is a flowchart showing the details of the processing performed by the main control unit 100 in this embodiment. Recovery processing is performed in step S1501. There is no particular restriction on the recovery processing method, but a recovery method with a higher ink replacement rate is preferable in that it can better eliminate the effect of temperature accumulation. In step S1502, circulation begins. Thereafter, circulation state detection control is performed as in the second embodiment. This embodiment makes it possible to detect the circulation state after recovery processing, understand the effect of the recovery processing, and prevent erroneous detection.

[0069] As described above, the configuration of each embodiment makes it possible to determine whether the ink circulation state within the print head is normal. Therefore, if it is detected that the circulation state is insufficient, processing within the print head is performed, and the ink circulation is normal, and the impact on the ejection ports due to increased ink viscosity is suppressed, allowing for normal printing.

[0070] [Configuration 1] a print head including a discharge port for discharging ink and a pressure chamber filled with ink to be discharged from the discharge port, the print head performing a printing operation by discharging ink from the discharge port; a circulation unit that performs a circulation operation for circulating ink in a circulation path including the pressure chamber when the recording operation is performed; A control unit; A recording device having: The control unit While the circulation unit is performing the circulation operation, temperature information is acquired, which is information regarding the temperature of the print head. A circulation state of the ink in the circulation path is determined based on the information about the temperature. A recording device characterized by: [Configuration 2] The control unit While the circulation means is performing the circulation operation, first temperature information is acquired, which is the temperature information at a first timing, and second temperature information is acquired, which is the temperature information at a second timing after the first timing; The difference between the first temperature information and the second temperature information is compared with a threshold value to determine the circulation state of the ink in the circulation path. 2. The recording device according to claim 1, [Configuration 3] The control unit determines that the circulation state is normal if the difference between the first temperature information and the second temperature information is less than the threshold value. 3. The recording device according to claim 2. [Configuration 4] If the difference between the first temperature information and the second temperature information is equal to or greater than the threshold value, the control unit determines that the circulation state is not normal and performs recovery processing for the print head or notifies the state of the print head. 4. The recording apparatus according to claim 2, wherein the recording apparatus is a recording medium. [Configuration 5] The control unit When the circulation means is performing the circulation operation, the temperature at the first timing and acquiring first temperature information, which is temperature information at a second timing after the first timing, and second temperature information, which is temperature information at a second timing after the first timing; A coefficient indicating a temperature change per unit time is calculated based on the first temperature information and the second temperature information, and the coefficient is compared with a threshold value to determine the circulation state of the ink in the circulation path. 2. The recording device according to claim 1, [Configuration 6] The control unit determines that the circulation state is normal if the coefficient is less than the threshold value. 6. The recording device according to claim 5, [Configuration 7] If the coefficient is equal to or greater than the threshold value, the control unit determines that the circulation state is not normal and performs recovery processing for the print head or notifies the state of the print head. 7. The recording device according to claim 5 or 6. [Configuration 8] The control unit determines the circulation state after the recording operation using the recording head. 8. The recording device according to claim 1, wherein the recording device is a recording medium. [Configuration 9] The control unit does not determine the circulation state before a predetermined time has elapsed after the recording operation. 9. The recording device according to claim 8. [Configuration 10] The control unit determines the circulation state after a recovery process for the recording head. 10. The recording device according to claim 1, wherein the recording device is a recording medium. [Configuration 11] The control unit determines the circulation state before the recording operation using the recording head. 11. The recording device according to claim 1, wherein the recording device is a recording medium. [Configuration 12] The threshold value is a predetermined value. 8. The recording device according to claim 2, wherein the recording device is a recording medium. [Configuration 13] The threshold value is a value determined based on at least one of the environmental temperature of the recording device, the recording time of the recording operation immediately before the ink circulation state is determined, and the amount of ink applied in the recording operation immediately before the ink circulation state is determined. 8. The recording device according to claim 2, wherein the recording device is a recording medium. [Configuration 14] the print head has a plurality of temperature detection elements on a substrate on which the ejection ports are formed, The control unit acquires the maximum value of the detection values of the plurality of temperature detection elements as the temperature information. 14. The recording device according to claim 1, wherein the recording device is a recording medium. [Configuration 15] the print head has a plurality of temperature detection elements on a substrate on which the ejection ports are formed, The control unit acquires, as the temperature information, a detection value by a temperature detection element that is closest to the ejection port, among detection values of the plurality of temperature detection elements. 14. The recording device according to claim 1, wherein the recording device is a recording medium. [Configuration 16] The circulation means includes a pump driven by the control unit. 16. The recording device according to claim 1, wherein the recording device is a recording medium. [Explanation of symbols]

[0071] 9: recording head, 23: pressure chamber, 50: recording device, 100: main control unit, 132: discharge port, 408: pump

Claims

1. a print head including an ejection port for ejecting ink and a pressure chamber filled with ink to be ejected from the ejection port, the print head ejecting ink from the ejection port to perform a printing operation; a circulation unit that performs a circulation operation for circulating ink in a circulation path including the pressure chamber when the recording operation is performed; A control unit; A recording device having: The control unit While the circulation unit is performing the circulation operation, temperature information is acquired, which is information regarding the temperature of the print head. A circulation state of the ink in the circulation path is determined based on the information about the temperature. A recording device characterized by:

2. The control unit While the circulation unit is performing the circulation operation, first temperature information is acquired, which is the temperature information at a first timing, and second temperature information is acquired, which is the temperature information at a second timing that is later than the first timing; The difference between the first temperature information and the second temperature information is compared with a threshold value to determine the circulation state of the ink in the circulation path.

2. The recording apparatus according to claim 1, wherein the recording apparatus is a recording medium.

3. The control unit determines that the circulation state is normal if the difference between the first temperature information and the second temperature information is less than the threshold value.

3. The recording apparatus according to claim 2.

4. If the difference between the first temperature information and the second temperature information is equal to or greater than the threshold value, the control unit determines that the circulation state is not normal and performs recovery processing for the print head or notifies the state of the print head.

3. The recording apparatus according to claim 2.

5. The control unit While the circulation unit is performing the circulation operation, first temperature information is acquired, which is the temperature information at a first timing, and second temperature information is acquired, which is the temperature information at a second timing that is later than the first timing; A coefficient indicating a temperature change per unit time is calculated based on the first temperature information and the second temperature information, and the coefficient is compared with a threshold value to determine the circulation state of the ink in the circulation path.

2. The recording apparatus according to claim 1, wherein the recording apparatus is a recording medium.

6. The control unit determines that the circulation state is normal if the coefficient is less than the threshold value.

6. The recording apparatus according to claim 5.

7. If the coefficient is equal to or greater than the threshold value, the control unit determines that the circulation state is not normal and performs recovery processing for the print head or notifies the state of the print head.

6. The recording apparatus according to claim 5.

8. The control unit determines the circulation state after the recording operation using the recording head. to give 8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

9. The control unit does not determine the circulation state before a predetermined time has elapsed after the recording operation.

9. The recording apparatus according to claim 8.

10. The control unit determines the circulation state after a recovery process for the recording head.

8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

11. The control unit determines the circulation state before the recording operation using the recording head.

8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

12. The threshold value is a predetermined value.

8. The recording apparatus according to claim 2, wherein the recording medium is a recording medium.

13. The threshold value is a value determined based on at least one of the environmental temperature of the recording device, the recording time of the recording operation immediately before the ink circulation state is determined, and the amount of ink applied in the recording operation immediately before the ink circulation state is determined.

8. The recording apparatus according to claim 2, wherein the recording medium is a recording medium.

14. the print head has a plurality of temperature detection elements on a substrate on which the ejection ports are formed, The control unit acquires the maximum value of the detection values of the plurality of temperature detection elements as the temperature information.

8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

15. the print head has a plurality of temperature detection elements on a substrate on which the ejection ports are formed, The control unit acquires, as the temperature information, a detection value by a temperature detection element that is closest to the ejection port, among detection values of the plurality of temperature detection elements.

8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

16. The circulation means includes a pump driven by the control unit.

8. The recording apparatus according to claim 1, wherein the recording medium is a recording medium.

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