Recording device, control method, storage medium, and program

Abstract

This technology provides a way to prevent nozzles that have not experienced a serious decrease in dispensing performance from being incorrectly identified as non-dispensing. [Solution] The recording device comprises: a discharge means having a nozzle for discharging liquid onto a recording medium; a circulation means for circulating the liquid between the discharge means and a liquid storage section containing the liquid; a detection means for detecting the liquid discharge state of the nozzle; an acquisition means for acquiring temperature information of the nozzle; and, when the discharge state is detected by the detection means after a recording operation in which the discharge means records onto the recording medium, a setting means for setting a detection preparation time based on the temperature information, during which the circulation means circulates the liquid between the end of the recording operation and the detection of the discharge state.

Description

Technical Field

[0001] The present invention relates to a recording apparatus.

Background Art

[0002] In a recording apparatus typified by an inkjet recording apparatus, an image is recorded on a recording medium by discharging ink from nozzles of a discharge head. In such a recording apparatus, the discharge performance of the nozzles may deteriorate due to clogging of the nozzles or the like, and there may be a case where it becomes difficult to discharge ink (non-discharge). Patent Document 1 discloses a technique for detecting non-discharge of nozzles and performing image compensation or recovery of the discharge performance of the nozzles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Due to the temperature of the discharge head, the moisture in the ink in the nozzles evaporates and the ink thickens. In some cases, the nozzles may be determined to be non-discharging due to the thickened ink. However, nozzle non-discharge caused by ink thickening may be resolved by reducing the degree of thickening. Therefore, for example, by performing a non-discharge determination after an aspiration operation or the like for aspirating ink from the nozzles, it is possible to avoid determining that nozzles that have not reached a serious deterioration in discharge performance are non-discharging. However, performing an aspiration operation or the like every time a non-discharge determination is made may increase the ink consumption or reduce the recording efficiency.

[0005] The present invention provides a technique for avoiding the determination that nozzles that have not reached a serious deterioration in discharge performance are non-discharging.

Means for Solving the Problems

[0006] According to the present invention, A dispensing means having a nozzle for dispensing liquid onto a recording medium, and a circulation means for circulating the liquid between the dispensing means and the liquid storage section containing the liquid, A detection means for detecting the liquid discharge state of the nozzle, An acquisition means for acquiring the temperature information of the nozzle, The system includes a setting means for setting a detection preparation time based on temperature information, during which the liquid is circulated by the circulation means between the end of the recording operation and the detection of the discharge state, when the discharge state is detected by the detection means after a recording operation in which the discharge means records to the recording medium. A recording device characterized by the above is provided. [Effects of the Invention]

[0007] This invention provides a technique to avoid misidentifying nozzles that have not experienced a serious decrease in dispensing performance as non-dispensing. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram of a recording device according to one embodiment of the present invention. [Figure 2] Block diagram of the control unit of the recording device shown in Figure 1. [Figure 3] Perspective view of the discharge head. [Figure 4] A schematic diagram and a close-up view of the chip's configuration. [Figure 5] Diagram illustrating the recovery unit. [Figure 6] Diagram illustrating the recovery unit. [Figure 7] Diagram illustrating the circulation system. [Figure 8] A flowchart for temperature control. [Figure 9] (a) is a table showing the correspondence between the difference between the target temperature and the detected temperature and the sub-heater rank, and (b) is a table showing the correspondence between the sub-heater rank and the operating time. [Figure 10](a) to (c) are explanatory diagrams for explaining the action of liquid circulation on the thickening of liquid in the nozzle. [Figure 11] (a) and (b) are diagrams showing the temperature change of the nozzle in the discharge state. [Figure 12] Flowchart showing an example of the process executed by the main control unit. [Figure 13] Diagram showing an example of a table for setting the detection preparation time. [Figure 14] Flowchart showing an example of the process executed by the main control unit. [Figure 15] Diagram showing an example of a table for setting the detection preparation time. [Figure 16] Diagram showing an example of a table for setting the detection preparation time. [Figure 17] Flowchart showing an example of the process executed by the main control unit. [Figure 18] Flowchart showing an example of the process executed by the main control unit.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0010] <First Embodiment> (Configuration of the Recording Device) FIG. 1 is a schematic diagram of a recording apparatus 101 according to an embodiment of the present invention and is a front view of the recording apparatus 101. The recording apparatus 101 of the present embodiment is an inkjet recording apparatus that performs recording by ejecting a liquid onto a recording medium. The recording apparatus of the present embodiment is a sheet-fed recording apparatus that can record an image by ejecting a plurality of types of inks having different colors from a reaction liquid as the liquid onto the recording medium. Note that the recording method is not limited to the sheet-fed type, and a rotary type that performs recording on a roll paper or the like may be used. In each figure, arrows X and Y indicate horizontal directions orthogonal to each other, and arrow Z indicates the vertical direction. The X direction is the longitudinal direction of the recording apparatus 101, and the Y direction is the width direction of the recording apparatus 101.

[0011] Note that "recording" includes not only the case of forming significant information such as characters and figures, but also the case of forming an image, pattern, pattern, etc. on the recording medium regardless of whether it is significant or not, or performing processing on the medium, regardless of whether it is manifested so that it can be perceived visually by a human. Further, in the present embodiment, a sheet-like paper is assumed as the "recording medium", but it may be cloth, plastic film, or the like.

[0012] The recording apparatus 101 is composed of modules such as a paper feeding module 1000, a recording module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, a reversing module 6000, and a paper discharging and stacking module 7000. The sheet S, which is cut paper supplied from the paper feeding module 1000, is conveyed along a conveyance path in the X direction, processed by each module, and discharged to the paper discharging and stacking module 7000.

[0013] The paper feeding module 1000 has three accommodating portions 1100a to 1100c for accommodating the sheet S. Each of the accommodating portions 1100a to 1100c can be pulled out to the front side of the apparatus. The sheet S is fed one by one by a separation belt and a conveyance roller in each of the accommodating portions 1100a to 1100c and conveyed to the recording module 2000. Note that the number of the accommodating portions 1100a to 1100c is not limited to three, and may be one, two, or four or more.

[0014] The recording module 2000 includes a register correction unit (not shown), a belt unit 2200, and a recording unit 2300. Sheets S transported from the paper feed module 1000 are corrected for tilt and position by the register correction unit and then transported to the belt unit 2200. The recording unit 2300 is positioned opposite the belt unit 2200. The recording unit 2300 has multiple discharge heads (recording heads) 22 that discharge liquid onto the transported sheets S from above.

[0015] The sheet S is transported by suction using a belt unit 2200, ensuring clearance between the sheet and the discharge surface (bottom surface) of the discharge head 22. Multiple discharge heads 22 are arranged in a row along the transport direction (X direction). In this embodiment, five discharge heads 22 are provided, and each head discharges one of four inks: Ye (yellow), Ma (magenta), Cy (cyan), and Bk (black), or Pr (reaction solution). Each discharge head 22 is a full-line head extending in the Y direction, and the liquid discharge range in the Y direction includes the width of the sheet S. The number of discharge heads 22 and the type of liquid discharged are not limited to those described above. In this embodiment, a method using a heating element is employed as the liquid discharge method. However, other methods such as a method using a piezoelectric element, a method using an electrostatic element, or a method using a MEMS element can also be employed.

[0016] Each color of ink and reaction solution is supplied to the discharge head 22 via tubes from an ink tank (not shown). The sheet S on which the image has been recorded by the recording unit 2300 is transported by the belt unit 2200. A scanner may be placed downstream of the recording unit 2000 in the transport direction to detect misalignment and color density of the image formed on the sheet S and correct the recording operation.

[0017] The drying module 3000 includes a decoupling unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 is a unit that reduces the liquid content in the ink applied to the sheet S by the recording unit 2300, thereby improving the adhesion between the sheet S and the ink. The sheet S on which an image has been recorded by the recording unit 2300 of the recording module 2000 is transported to the decoupling unit 3200 located within the drying module 3000. The decoupling unit 3200 can transport the sheet S from above using air pressure and belt friction. By loosely holding and transporting the sheet S on the belt, displacement of the sheet S on which the ink image has been formed is prevented.

[0018] The sheet S, transported from the decoupling unit 3200, is then carried by suction on the drying belt unit 3300. Simultaneously, hot air is applied from the hot air blowing unit 3400 located above the belt to dry the ink-applied surface of the sheet S. In addition to the method of applying hot air, the drying method may also be configured by combining a method of irradiating the surface of the sheet S with electromagnetic waves (such as ultraviolet or infrared rays) or a conductive heat transfer method using contact with a heating element.

[0019] The fixing module 4000 has a fixing belt unit 4100. The sheet S conveyed from the drying module 3000 passes between a heated upper belt unit and a heated lower belt unit in the fixing belt unit 4100. This allows the ink to be fixed to the sheet S.

[0020] The cooling module 5000 has multiple cooling units 5100 and cools the high-temperature sheet S conveyed from the fixing module 4000. The cooling units 5100 draw outside air into the cooling box with a fan, increase the pressure inside the cooling box, and cool the sheet S by blowing air from nozzles formed in the conveying guide onto the sheet S. The cooling units 5100 are arranged on both sides in the Z direction with respect to the conveying path, so that the sheet S can be cooled from both sides.

[0021] Furthermore, the cooling module 5000 has a switching unit for switching the transport path. The transport path of the sheet S can be switched depending on whether the sheet S is being transported to the inversion module 6000 or to the double-sided transport path used during double-sided recording.

[0022] During double-sided recording, the sheet S is transported to a transport path below the cooling module 5000 and further transported along the double-sided transport path of the fuser module 4000, drying module 3000, recording module 2000, and paper feed module 1000. The sheet S is then transported again to the register correction unit, belt unit 2200, and recording unit 2300 of the recording module 2000, where the image is recorded. The fuser module 4000 is equipped with a reversal unit 4200 in the middle of the double-sided transport path to reverse the front and back sides of the sheet S.

[0023] The reversal module 6000 has a reversal unit 6400. The orientation of the ejected sheets S can be freely changed. The ejection and stacking module 7000 has a top tray 7200 and a stacking section 7500, and stacks the sheets S transported from the reversal module 6000 in an aligned manner.

[0024] The recovery unit 17 is a mechanism for maintaining and restoring the discharge performance of the discharge head 22. The recovery unit 17 has a cap section 18 on which a cap mechanism 181 (see Figure 4) is located, and a cleaning section 19 on which a cleaning mechanism 191 (see Figure 5) is located. The cap section 18 and the cleaning section 19 are movable in the X direction by a drive mechanism (not shown).

[0025] (Control unit) Figure 2 is a block diagram of the control unit in the recording device 101. The control unit is an electronic circuit having a main control unit 111 and a recording engine unit 200. The controller 209 controls various mechanisms of the recording engine unit 200 according to instructions from the main controller 201 of the main control unit 111. The details of the control configuration are described below.

[0026] In the main control unit 111, the main controller 201, which is composed of a CPU, controls the entire recording device 101 using the RAM 205 as the work area, according to the program and various parameters stored in the ROM 206. For example, when a recording job is input from the host device 114 via the host interface (IF) 202, the image processing unit 207 performs predetermined image processing on the received image data according to the instructions of the main controller 201. Then, the main controller 201 transmits the processed image data to the recording engine unit 200 via the engine interface (IF) 204.

[0027] The recording device 101 may acquire image data from the host device 114 via wireless or wired communication, or it may acquire image data from an external storage device (such as a USB memory stick) connected to the recording device 101. The communication method used for wireless or wired communication is not limited. For example, Wi-Fi (Wireless Fidelity) (registered trademark) and Bluetooth (registered trademark) can be used as communication methods for wireless communication. USB (Universal Serial Bus) and the like can be used as communication methods for wired communication.

[0028] The operation unit 113 is a mechanism for the user to perform input and output to the recording device 101, and is, for example, a touch panel. The user can set the recording mode and recognize information from the recording device 101 via the operation unit 113.

[0029] In the recording engine unit 200, the controller 209, which is composed of a CPU, controls the various mechanisms of the recording device 101, using the RAM 211 as the work area, according to the program and various parameters stored in the ROM 210.

[0030] When various commands and image data are received via the controller interface (IF) 208, the controller 209 temporarily stores them in the RAM 211. The controller 209 instructs the image processing controller 212 to convert the stored image data into recording data that the discharge head 22 can use for recording operations. Once the recording data is generated, the controller 209 instructs the discharge head 22 to perform a liquid discharge operation based on the recording data via the head interface (IF) 217. At this time, the controller 209 controls the transport operation of the sheet S via the transport control unit 216. In accordance with the instructions of the controller 209, the discharge operation by the discharge head 22 is performed in conjunction with the transport operation of the sheet S, and the recording operation is carried out.

[0031] The movement control unit 215 changes the position of the discharge head 22 according to the operating status of the recording device 101, such as the maintenance status and recording status. The supply control unit 213 controls the circulation device 218 so that the pressure of the liquid supplied to the discharge head 22 is within an appropriate range. Details of the circulation device 218 will be described later.

[0032] The recovery control unit 214 controls the operation of the recovery unit 17 when performing recovery operations related to the discharge performance of the discharge head 22. The temperature control control unit 220 controls the temperature of the discharge head 22 so that it remains within an appropriate range when the recording operation is performed. The non-discharge determination unit 219 determines the discharge state of each nozzle based on the detection results of sensors 226 that detect the liquid discharge state of each nozzle of the discharge head 22. In this embodiment, the sensor 226 is provided for each nozzle and is a temperature sensor that detects the temperature of the nozzle. In this embodiment, the temperature change after the driving voltage for discharging liquid is applied to the heating element of the nozzle is measured by the temperature sensor 226. The discharge state of each nozzle is determined by whether or not there is an inflection point in the temperature change curve, which is the result of the detection.

[0033] Figure 11(a) shows the temperature waveform before filtering for non-discharge detection in this embodiment. In this embodiment, the non-discharge determination unit 219 determines the discharge state for each nozzle by acquiring the waveform of the temperature change for each nozzle before and after discharge.

[0034] Figure 11(a) compares the waveforms of temperature changes in the ejection state and the non-ejection state, with the horizontal axis representing time and the vertical axis representing the output value of sensor 226 (lower voltage indicates higher temperature). In both the ejection and non-ejection states, applying the drive voltage to the heating element of the nozzle causes the temperature to rise, and then the temperature drops after ejection. However, the temperature drops more in the ejection state than in the non-ejection state. During ejection, the temperature drops at the moment when the stretched portion of the ink droplet returns to the nozzle side. If no ink droplet is ejected, the temperature does not drop, so this difference allows us to determine whether or not the system is in a non-ejection state.

[0035] Figure 11(b) shows the waveform of the temperature change after filtering for non-discharge detection in this embodiment. In the state shown in Figure 11(a), the difference between the discharge state and the non-discharge state is small, and there is a possibility of false detection due to the influence of noise. In this embodiment, the non-discharge determination unit 219 performs filtering by differentiating and amplifying the waveform of the temperature change. In this embodiment, a threshold is set in Figure 11(b), and if the peak of the waveform of the temperature change is above the threshold, it is determined to be a discharge state, and if it is below the threshold, it is determined to be a non-discharge state.

[0036] This method for determining non-discharge is merely one example, and other methods can also be employed. For example, an optical sensor may be positioned so that the ejected ink droplets obstruct the optical axis, and the ejection status of each nozzle may be determined by detecting the presence or absence of ink droplets obstructing the optical axis. Alternatively, an inspection pattern may be recorded in the margin of the sheet S, and the ejection status of each nozzle may be determined by optically reading the inspection pattern with a sensor (scanner).

[0037] (Discharge head configuration) The configuration of the discharge head 22 will now be described. Figure 3 is a perspective view of the discharge head 22. The discharge head 22 has a tip 223 equipped with multiple nozzles for discharging liquid, which is arranged in the longitudinal direction (Y direction) of the discharge head 22. Positioning parts 221 are provided at both ends of the discharge head 22 in the Y direction for positioning the discharge head 22 in a predetermined position in the recording unit 2300. The positioning part 221 includes a contact part 221a consisting of a recess with a conical slope, a contact part 221b consisting of a groove with two V-shaped planes, and a contact part 221c consisting of a plane.

[0038] Figure 4 is a schematic diagram and a partially enlarged view illustrating the configuration of the chip 223. The chip 223 is provided with a plurality of subheaters 224 for adjusting the temperature of the chip 223. The subheaters 224 are heating elements different from the heating elements provided in each nozzle, and are provided in two rows in each of the 40 temperature control regions shown in a grid. The 40 temperature control regions are identified by dividing the chip 223 into 10 sections in the Y direction and 4 sections in the X direction, as shown by the solid lines. A temperature sensor 225 is also provided in each temperature control region.

[0039] The tip 223 also has nozzle rows in each of the 16 regions in the X direction, as shown by the dashed lines. Each nozzle row consists of a number of nozzles 309 arranged in the Y direction, and in this embodiment, the tip 223 has 16 nozzle rows.

[0040] As shown in the enlarged section of Figure 4 (elliptical region), subheaters 224 are positioned above and below the row of nozzles 309. A temperature sensor 226 is associated with each nozzle 309, and temperature information for determining non-discharge status is obtained for each nozzle 309 by the temperature sensor 226.

[0041] The number and arrangement of the subheaters 224 are not limited to those shown in Figure 4; any number and arrangement that allows for temperature control of the entire area of ​​the chip 223 by the subheaters 224 is acceptable. Similarly, the number and arrangement of the temperature sensors 225 are not limited to those shown in Figure 4; any number and arrangement that allows for the acquisition of temperature information for each subheater 224 is acceptable. Furthermore, the arrangement and shape of the chips 223 are not limited to those shown in Figure 4. For example, the shape of the chips 223 may be a parallelogram other than the rectangle shown, or it may be a rectangle, trapezoid, or other quadrilateral. Moreover, the discharge head 22 may be configured to have multiple chips 223 arranged in the short direction of the discharge head 22, or the arrangement of the chips 223 in the discharge head 22 may be a staggered arrangement.

[0042] (Composition of the recovery unit) The configuration of the recovery unit 17 will be described with reference to Figures 5 and 6. As shown in Figure 5, each cap mechanism 181 within the cap section 18 is equipped with multiple spherical positioning members 182 for positioning the discharge head 22. The positioning members 182 are arranged at each end of the cap mechanism 181 in the sheet width direction (Y direction). Three positioning members 182 are required to position one discharge head 22 relative to the cap mechanism 181, with one on the front side and two on the back side. The positioning of the discharge head 22 and the cap mechanism 181 is achieved when the positioning sections 221 provided at both ends of the discharge head 22 come into contact with the positioning members 182 of the cap mechanism 181. By being positioned relative to the discharge head 22, the cap mechanism 181 protects the tip 223 of the discharge head 22 and enables negative pressure suction by the negative pressure suction mechanism described later.

[0043] As shown in Figure 6, the cleaning unit 19 is equipped with multiple spherical positioning members 192 for positioning multiple discharge heads 22. The positioning members 192 are located inside the cleaning unit 19, at each end in the sheet width direction (Y direction), and are held by beam members 193a and 193b that are arranged across the sheet transport direction. Three positioning members 192 are required to position one discharge head 22 relative to the cleaning unit 19, with one located on the front beam member 193a and two on the rear beam member 193b inside the cleaning unit 19. The positioning of the discharge head 22 and the cleaning unit 19 is achieved by the positioning parts 221 provided at both ends of the discharge head 22 contacting the positioning members 192 of the cleaning unit 19.

[0044] Furthermore, the positioning configuration is not limited to a configuration using a spherical positioning member; it may also be a configuration in which a part of the discharge head 22 abuts against the cleaning section 19, or a configuration in which positioning is performed using holes and pins provided in the cleaning section 19 and the discharge head 22.

[0045] The cleaning mechanism 191 includes a cleaning fluid application unit 50, a fluid removal unit 60, and a negative pressure application unit 70. The cleaning fluid application unit 50 applies cleaning fluid to the tip 223 of the discharge head 22. The fluid removal unit 60 removes ink, paper dust, and cleaning fluid adhering to the discharge head 22. The negative pressure application unit 70 applies negative pressure to the tip 223 of the discharge head 22 to remove ink adhering to the nozzle 309 and remove bubbles in the flow path.

[0046] Furthermore, as shown in Figure 6, the cleaning unit 19 has a moving mechanism (not shown) that moves the cleaning mechanism 191 along a wiping direction D perpendicular to the sheet transport direction. The cleaning mechanism 191 removes ink and debris from the nozzle surface of the discharge head 22 by a combination of a cleaning liquid application unit 50, a liquid removal unit 60, and a negative pressure application unit 70.

[0047] During maintenance, the operation of each unit is as follows: the discharge head 22 is moved away from the cap 18 in the device height direction (Z direction) from a state where the discharge head 22 and the cap 18 are in contact; the cap 18 is moved away from the discharge head 22 in the device longitudinal direction (X direction); and the cleaning unit 19 is moved closer to the discharge head 22 in the device longitudinal direction (X direction).

[0048] Next, the discharge head 22 is moved in the device height direction (Z direction) toward the cleaning unit 19, and cleaning is performed with the discharge head 22 and the cleaning unit 19 in contact. Once cleaning is complete, the discharge head 22 is moved away from the cleaning unit 19 in the device height direction (Z direction) from the state where the discharge head 22 and the cleaning unit 19 are in contact. The cleaning unit 19 is moved away from the discharge head 22 in the device longitudinal direction (X direction), and the cap unit 18 is moved toward the discharge head 22 in the device longitudinal direction (X direction). Finally, the discharge head 22 is moved toward the cap unit 18 in the device height direction (Z direction), and maintenance is completed with the discharge head 22 and the cap unit 18 in contact.

[0049] (circulation device) The configuration of the circulation device 218 will be described with reference to Figure 7. Figure 6 is a schematic diagram of the circulation device 218 provided for each discharge head 22 (Ye, Ma, Cy, Bk, Pr) in the recording device of this embodiment. Figure 7 shows the configuration of one circulation device 218, and the recording device 101 is equipped with a circulation device 218 for each discharge head 22.

[0050] The discharge head 22 is connected to a liquid storage section (buffer tank) 301 that contains liquid by a liquid supply passage 302, and the liquid supply passage 302 is filled with liquid. The circulation device 218 drives the upstream pump 303 to remove impurities from the ink in the liquid storage section using a filter 304 and supply it to the discharge head 22. A valve 305 that can be switched between an open state and a closed state is provided between the upstream pump 303 and the discharge head 22.

[0051] The ejection head 22 includes an upstream liquid chamber 306 in the direction of liquid supply flow and a downstream liquid chamber 308. When liquid is filled into each of the two divided liquid chambers, ink is ejected from the nozzle 309 to record an image on the recording medium sheet S. A filter 307 is provided between the liquid chambers 306 and 308 to separate them. This filter 307 may have a mesh structure with many holes. This filter 307 can reduce the ingress of impurities into the liquid chamber 308.

[0052] In the discharge head 22, liquid is discharged based on image data, while the liquid that was not discharged and filled into the liquid chamber 308 is recovered into the liquid storage section via the downstream flow path 310 by the drive of the downstream pump 311. The circulation device 218 drives the downstream pump 311 and the upstream pump 303 to configure a circulation path that circulates the liquid from the liquid supply flow path 302 through the discharge head 22 and then through the downstream flow path 310 to the liquid storage section.

[0053] Furthermore, the circulation device 218 includes a relief valve 312 and a relief passage 313, which are differential pressure valves for releasing the liquid supply pressure from the upstream pump 303, in order to keep the supply pressure on the discharge head 22 constant when supplying liquid to the discharge head 22. The relief valve 312 is not opened and closed by a drive mechanism, but is constantly biased by a spring, and is configured to open when a predetermined pressure is reached. For example, if the amount of liquid supplied per unit time from the upstream pump 303 is greater than the sum of the discharge amount per unit time from the discharge head 22 and the flow rate per unit time from the downstream pump 311, the relief valve 312 opens in accordance with the pressure acting on it. This forms a circulating passage consisting of a part of the ink supply passage 302, the relief passage 313, and the liquid storage section 301. By providing the relief passage 313, the amount of ink supplied to the discharge head 22 is adjusted according to the amount of ink consumed by the discharge head 22, and the pressure in the ink supply passage 302 can be stabilized regardless of the image data.

[0054] When replacing the ejection head 22, it is necessary to open the inside of the ejection head 22 to the atmosphere when performing the ink removal process. For this reason, an ink removal channel 315 and an ink removal valve 314 are provided, which branch off from the valve 305 in the ink supply channel 302 to the ejection head 22 and allow for communication with the atmosphere.

[0055] The circulation device 218 may continuously circulate the liquid in the flow path by constantly driving the upstream pump 303 and the downstream pump 311 while the recording device 101 is powered on. However, constantly circulating the ink in the flow path will increase the power consumption of the recording device 101. Therefore, it is desirable to circulate the liquid at the minimum necessary intervals.

[0056] The circulation period is, for example, 5 minutes after the recording device 101 is powered on. Alternatively, it is the period from the start to the end of the recording operation. Alternatively, it is the period from the start to the end of non-discharge detection. When the recording device 101 is powered off, the discharge head 22 is covered by the cap mechanism 181 to suppress evaporation of the liquid in the nozzle 309. However, if the power is off for a long time, evaporation gradually progresses and the ink in the nozzle 309 becomes thicker. Therefore, circulation is performed for 5 minutes after powering on to eliminate this thickening. Also, depending on the power-off time, the discharge performance of the nozzle may not be fully restored in 5 minutes of circulation, in which case cleaning is performed by the cleaning mechanism 191 after powering on. Furthermore, since the discharge head 22 is not covered by the cap mechanism 181 from the start to the end of the recording operation, the ink is circulated to stabilize discharge. And, although the discharge head 22 is covered by the cap mechanism 181 from the start to the end of non-discharge detection, the ink is circulated to perform non-discharge detection under the same conditions as during the recording operation.

[0057] (Temperature control) The temperature control of the discharge head 22 will now be described. Figure 8 is a flowchart of the temperature control performed by the temperature control control unit 220, which is executed when a recording job is started. Temperature control is performed for each temperature control area as described with reference to Figure 4. In S1, the detection results are obtained from each temperature sensor 225. In S2, the difference ΔT between the target temperature and the temperature detected by the temperature sensor 225 is calculated.

[0058] In S3, a sub-heater rank is selected for each temperature control region according to ΔT. The sub-heater rank will be described later. In S4, the sub-heater 224 for the corresponding temperature control region is driven by the sub-heater rank selected in S3. In this embodiment, if the target temperature is set to 37°C and the temperature detected by the temperature sensor 225 is less than 37°C, the sub-heater driving time increases as ΔT increases.

[0059] Then, in S5, if the temperature control flag is ON, the temperature control unit 220 repeats the processes from S1 to S4, and terminates the process when the temperature control flag is turned OFF. The temperature control flag is turned OFF when the recording job is completed.

[0060] In this embodiment, the temperature control temperature of the ejection head 22 is set to 37°C, but it is not limited to 37°C, and the temperature control temperature of the ejection head 22 may be changed depending on the configuration of the ejection head 22 and the physical properties of the ink. Furthermore, the purpose of temperature control of the ejection head 22 is to ensure the stability of ink ejection, that is, to reduce variations in the ejection amount by reducing the temperature distribution within the tip 223. Therefore, if the stability of liquid ejection is not a problem even without temperature control of the ejection head 22, it is not necessary to temperature control the ejection head 22.

[0061] The subheater rank and subheater operating time in S3 and S4 of Figure 8 will be explained below. Figure 9(a) is a correspondence table between ΔT and subheater rank. In Figure 9(a), the larger ΔT, the larger the value of the subheater rank. For example, when ΔT = 0.3, the subheater rank = 3, and when ΔT = 1.2, the subheater rank = 9. Figure 9(b) is a correspondence table between subheater rank and subheater operating time. In Figure 9(b), the larger the subheater rank, the larger the subheater operating time. For example, when the subheater rank is 3, the subheater operating time = 3 (= 1 + 1 + 1) and the subheater non-operating time = 13. When the subheater rank is 9, the subheater operating time = 9 (= 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1) and the subheater non-operating time = 7. In this embodiment, the unit of subheater operating time is 3 μs. When the subheater rank is 3, the system repeats between 9 μs of subheater operation and 39 μs of subheater deactivation. When the subheater rank is 9, the system repeats between 27 μs of subheater operation and 21 μs of subheater deactivation.

[0062] (Increased viscosity and non-discharge of liquid in the nozzle) The circulation of the liquid by the circulation device 218 has the effect of eliminating the thickening of the liquid that occurs in the nozzle 309. However, the effect varies depending on the degree of thickening. The following explanation will be given with reference to Figures 10(a) to 10(c). Figures 10(a) to 10(c) are schematic diagrams of the vicinity of the nozzle 309 viewed from the side. The nozzle 309 has an opening that opens on the lower surface of the discharge head 22, and a liquid circulation channel is connected to this opening. The nozzle 309 has a heating element 309a that discharges liquid at a position opposite the opening. Arrow d1 indicates the direction of the circulating liquid flow, and a longer length indicates a faster flow velocity. Arrow d2 indicates the evaporation of water from the liquid, and a greater number of arrows indicates a greater amount of evaporation. Arrow d3 indicates the dissolution of the thickened liquid in the circulating flow, and a greater number of arrows indicates a greater amount of dissolution.

[0063] Figure 10(a) illustrates the state near the nozzle 309 when there is no temperature rise in the discharge head 22. In this embodiment, temperature control is not performed when recording is not in progress. Therefore, the temperature of the liquid in the nozzle 309 and the temperature of the liquid in the circulation path are approximately the same.

[0064] The initial state in Figure 10(a) shows the state immediately after the start of liquid circulation. Since the liquid near nozzle 309 is not thickened, there is no decrease in the thickened liquid due to dissolution into the circulating liquid, and instead, there is an increase in the thickened liquid due to evaporation. As the amount of thickened liquid near nozzle 309 increases, the amount of thickened liquid dissolved in the circulating flow increases, and the amount of liquid evaporated decreases. The liquid near nozzle 309 thickens until these two factors become equal.

[0065] Ultimately, the steady state shown in Figure 10(a) is reached. In the steady state, there is a relatively low-viscosity thickened liquid near the nozzle 309, but this does not hinder liquid discharge, so recovery of discharge performance is unnecessary.

[0066] Figure 10(b) illustrates the state near the nozzle 309 when the temperature rise of the discharge head 22 is relatively small. During recording, temperature control is performed, so the temperature of the liquid inside the nozzle 309 rises to 37°C, which is the target temperature for temperature control. When the liquid is further discharged, the thermal energy of the heating element 309a acts on the liquid, causing the liquid to rise in temperature.

[0067] The initial state in Figure 10(b) represents the state immediately after liquid circulation and temperature control have started. Since the liquid near nozzle 309 is not thickened, there is no decrease in the thickened liquid due to dissolution into the circulating flow, and an increase in the thickened liquid due to evaporation occurs. As the amount of thickened liquid near nozzle 309 increases, the amount of thickened liquid dissolved into the circulating flow increases, and the amount of liquid evaporated decreases. The ink near nozzle 309 thickens until these two factors become equal.

[0068] Ultimately, the steady state shown in Figure 10(b) is reached. The faster flow velocity of the circulating flow compared to Figure 10(a) is due to a decrease in the viscosity of the liquid near the nozzle 309, caused by the temperature control of the discharge head 22 and the rise in temperature during recording. The greater amount of thickened liquid dissolved in the circulating flow compared to Figure 10(a) is due to the increased flow velocity of the circulating flow near the nozzle 309. Also, the greater amount of liquid evaporation compared to Figure 10(a) is due to the increased temperature of the liquid near the nozzle 309. In the steady state, a thickened liquid with moderate viscosity exists near the nozzle 309. Discharge is difficult in this state, but the initial state shown in Figure 10(b) can be restored by circulating the liquid with the circulation device 218 without temperature control of the discharge head 22.

[0069] Figure 10(c) illustrates the state near the nozzle 309 when the temperature rise of the discharge head 22 is large. During recording, temperature control is performed, so the temperature of the liquid inside the nozzle 309 rises to 37°C, which is the target temperature for temperature control. When liquid is further discharged, the thermal energy of the heating element 309a acts on the liquid, causing it to rise in temperature. Figure 10(c) shows an example where there are many discharge nozzles during recording, and assumes a large temperature rise due to discharge.

[0070] The initial state in Figure 10(c) represents the state immediately after the start of liquid circulation and temperature control. Since the liquid near nozzle 309 is not thickened, there is no decrease in the thickened liquid due to dissolution into the circulating flow, and instead, there is an increase in the thickened liquid due to evaporation. As the amount of thickened liquid near nozzle 309 increases, the amount dissolved into the circulating flow increases and the amount of liquid evaporated decreases, so the liquid near nozzle 309 thickens until the two are equal.

[0071] Ultimately, the steady state shown in Figure 10(c) is reached. The faster flow velocity of the circulating flow compared to Figure 10(b) is due to a decrease in the viscosity of the liquid near the nozzle 309 caused by the temperature control of the discharge head 22 and the temperature rise during recording. The greater amount of thickening liquid dissolved in the circulating flow compared to Figure 10(b) is due to the increased flow velocity of the circulating flow near the nozzle 309. Also, the greater amount of liquid evaporation compared to Figure 10(b) is due to the increased temperature of the liquid near the nozzle 309. In the steady state, a highly viscous thickening liquid is present near the nozzle 309. Discharge is difficult in this state, so recovery of the discharge performance is necessary. Even if the liquid is circulated by the circulation device 218 without temperature control of the discharge head 22, it is not possible to recover to the initial state shown in Figure 10(c). In this case, the initial state shown in Figure 10(c) can be recovered by a recovery operation (e.g., pre-discharge or suction discharge) in the recovery unit 17.

[0072] In summary, if the viscosity of the liquid near nozzle 309 is in the steady state shown in Figure 10(a), no recovery is necessary. If the viscosity of the liquid near nozzle 309 is in the steady state shown in Figure 10(b), the liquid can be recovered to the initial state shown in Figure 10(b) by circulating it with the circulation device 218 without controlling the temperature of the discharge head 22. If the viscosity of the liquid near nozzle 309 is in the steady state shown in Figure 10(c), the liquid can be recovered to the initial state shown in Figure 10(c) using the recovery unit 17.

[0073] (Recovery of discharge performance due to circulation time) As shown in Figure 10(b), the circulation of liquid by the circulation device 218 has a certain effect in recovering the decrease in discharge performance caused by the viscosity increase of the liquid near the nozzle 309. By circulating the liquid by the circulation device 218 before the discharge state is determined by the non-discharge determination unit 219, it is possible to avoid determining that the nozzle 309 is not discharging when it has not yet experienced a serious decrease in discharge performance.

[0074] It is also possible to perform a recovery operation by the recovery unit 17 before the non-discharge determination unit 219 determines the discharge state. However, circulating the liquid with the circulation device 218 is more advantageous than the recovery operation by the recovery unit 17 in terms of increased liquid consumption and reduced recording efficiency due to recovery time. In particular, when the discharge head 22 is a full-line type as in this embodiment, it may take time to move to the recovery unit 17 and to perform operations after moving, making liquid circulation by the circulation device 218 advantageous.

[0075] When the discharge state is determined by the non-discharge determination unit 219 after the completion of a recording job, the degree of viscosity increase of the liquid near the nozzle 309 is affected by the degree of temperature rise of the discharge head 22 during the execution of the recording job. Therefore, in this embodiment, the time for circulating the liquid between the end of the recording operation and the detection of the discharge state is set based on the temperature of the discharge head 22. This prevents the nozzle 309 from being judged as non-discharging when it has not yet experienced a serious decrease in discharge performance, and also allows setting a waiting time before determining the discharge state to be only as long as necessary for the viscosity to be resolved according to the degree of liquid viscosity increase.

[0076] Figure 12 is a flowchart showing an example of processing performed by the main control unit 111, and in particular, it is a flowchart showing an example of processing to detect the nozzle discharge state after the recording operation.

[0077] In S11, the recording operation related to the recording job is started. In S12, temperature information of the nozzle 309 is acquired. In this embodiment, the temperature of the nozzle 309 is identified for each chip 223. As temperature information, the detection results of each temperature sensor 225 of the chip 223 are repeatedly acquired during the recording operation.

[0078] In S13, a provisional detection preparation time is set for each chip 223 each time temperature information is acquired in S12. In this embodiment, the detection preparation time is set based on the highest temperature among the detection results of each temperature sensor 225 of the chip 223. Figure 13 shows a table for setting this time.

[0079] In the table in Figure 13, for example, if the maximum temperature T is 41°C or higher but less than 42°C, the detection preparation time is set to 10 seconds. On the other hand, if the maximum temperature T is higher, 42°C or higher but less than 43°C, the detection preparation time is set to a longer 15 seconds.

[0080] Furthermore, in the example shown in Figure 13, the higher the maximum temperature T, the longer the detection preparation time is set. This is because the higher the maximum temperature, the more the liquid in the nozzle 309 thickens, and therefore it takes longer for the thickened liquid to dissipate through liquid circulation.

[0081] In the example shown in Figure 13, the detection preparation time is 0 seconds when the maximum temperature is below 40 degrees Celsius. This is because, at temperatures within this range, it is assumed that almost no viscosity increase of the liquid near the nozzle 309 occurs.

[0082] Return to Figure 12. In S14, the recording operation related to the recording job is completed. In S15, a detection preparation time is set for each ejection head 22. Here, first, the longest detection preparation time is identified for each ejection head 22 from among the detection preparation times for each chip 223 set in S13. The identified longest detection preparation time is set as the detection preparation time for that ejection head 22.

[0083] In S16, each discharge head 22 waits for the detection preparation time set in S15 while the liquid is circulated by the circulation device 218. Once the detection preparation time has elapsed, in S17, a discharge state detection process and a non-discharge determination process are performed for each discharge head 22. Here, liquid is discharged from each nozzle 306, and the non-discharge determination unit 219 identifies the nozzle 306 that is not discharging based on the detection result of the sensor 226.

[0084] As described above, in this embodiment, during the detection preparation time in S16, the upstream pump 303 and downstream pump 311 of the circulation device 218 are driven to circulate the liquid. The thickened liquid in the discharge head 22, which has thickened due to the recording operation, is diffused into the circulating flow, so the thickening of the liquid in the nozzle 309 is eliminated, as illustrated in Figure 10(b). Since the discharge state detection and non-discharge determination in S17 are performed with the thickening eliminated, the detection accuracy of non-discharge nozzles can be improved.

[0085] Furthermore, if the liquid is being circulated by the circulation device 218 while S16 is in standby mode, other operations can be performed. For example, operations such as changing the position of the discharge head 22 or the position of the cap portion 18 may be performed while in standby mode.

[0086] <Second Embodiment> If the thickened liquid cannot be eliminated by liquid circulation alone, a recovery operation may be performed to restore the discharge performance. In this embodiment, the execution of pre-discharge is controlled as a recovery operation. Pre-discharge is a liquid discharge operation that does not contribute to recording, with the aim of restoring the discharge performance of the nozzle 309. Figure 14 is a flowchart showing an example of processing performed by the main control unit 111 in this embodiment, and is a flowchart of a processing example that replaces the example in Figure 12.

[0087] In S21, the recording operation related to the recording job begins. The processes in S22 to S27 are repeatedly executed for each chip 223 during the recording operation.

[0088] In S22, temperature information of the nozzle 309 is acquired. In this embodiment, the temperature information is obtained from the detection results of each temperature sensor 225 of the chip 223. In S23, it is determined whether the highest temperature detected by each temperature sensor 225 of the chip 223 acquired in S22 is above a threshold. In this embodiment, the threshold is 46°C. If the highest temperature is above the threshold, the process proceeds to S25; otherwise, the process proceeds to S24.

[0089] In S24, the pre-ejection flag, which determines whether or not to perform pre-ejection after the recording operation, is set to OFF, and the process proceeds to S26. The pre-ejection flag is a flag whose ON and OFF states are managed using, for example, the recording area of ​​RAM 205. In S26, a provisional detection preparation time W is set. In this embodiment, the detection preparation time W' is set from the highest temperature among the detection results of each temperature sensor 225 of the chip 223. Figure 15 shows a table for setting this, and is a table that replaces the table in Figure 13. The example in Figure 15 is basically the same as the example in Figure 13, but in the example in Figure 15, there is no specification for the detection preparation time when the highest temperature T is 46℃ or higher. This is because, as will be described later, pre-ejection is performed when the highest temperature T is 46℃ or higher.

[0090] Return to Figure 14. In S25, the pre-discharge flag, which determines whether or not to perform pre-discharge after the recording operation, is set to ON, and the process proceeds to S27. In S27, the provisional detection preparation time W' is set to 0.

[0091] In S28, the recording operation related to the recording job is completed. In S29, it is determined whether there are any chips 223 with the reserve ejection flag ON for each ejection head 22. For ejection heads 22 that contain chips 223 with the reserve ejection flag ON, the process proceeds to S30. For ejection heads 22 where all reserve ejection flags are OFF, the process proceeds to S31.

[0092] In S30, pre-discharge is performed on the discharge head 22, including the tip 223 with the pre-discharge flag set to ON, while the liquid is circulated by the circulation device 218. The nozzles 309 that are subject to pre-discharge are all nozzles 309 of the tip 223 with the pre-discharge flag set to ON. In S32, the pre-discharge time Wd required for the pre-discharge in S30 is calculated, and then the process proceeds to S33.

[0093] In S31, the preliminary discharge time Wd is set to 0 seconds. In S33, a detection preparation time W is set for each discharge head 22. Here, first, a provisional detection preparation time Wmax is identified for each discharge head 22. In identifying the provisional detection preparation time Wmax, first, for each discharge head 22, the longest detection preparation time is identified from the detection preparation times W' for each chip 223 set in S26 or S27. The identified longest detection preparation time W' is set as the provisional detection preparation time Wmax for that discharge head 22.

[0094] The detection preparation time W is calculated as W = Wmax - Wd. In the discharge head 22 where preliminary discharge has been performed, the time for liquid circulation by the circulation device 218 during preliminary discharge is removed.

[0095] In S34, it is determined whether the detection preparation time W calculated for each discharge head 22 in S33 is W>0. If W>0, the process proceeds to S35; otherwise, the process proceeds to S36. In S35, each discharge head 22 waits for the detection preparation time W set in S33 while the liquid is circulated by the circulation device 218. Once the detection preparation time has elapsed, the process proceeds to S36. In S36, a discharge state detection process and a non-discharge determination process are performed for each discharge head 22. Here, liquid is discharged from each nozzle 306, and the non-discharge determination unit 219 identifies the nozzle 306 that is not discharging based on the detection result of the sensor 226.

[0096] As described above, in this embodiment, pre-discharge is performed for nozzles 309 of chips 223 whose temperature information indicates a temperature above a threshold. Since the thickened liquid in nozzles 309 that has thickened during the recording operation is discharged by pre-discharge, for example, the state of nozzle 309 changes from the steady state in Figure 10(c) to the initial state in Figure 10(c), and the thickening is eliminated. Since the discharge state detection and non-discharge determination in S36 are performed with the thickening eliminated, the detection accuracy of non-discharging nozzles can be improved. In addition, while pre-discharge is being performed, the liquid is circulated by the circulation device 218 in the discharge head 22, so that time is excluded from the detection preparation time. Therefore, the thickening of the liquid in nozzles 309 that are not pre-discharged is also eliminated, and unnecessary detection preparation time can be reduced.

[0097] <Third Embodiment> The detection preparation time may be varied depending on the position of the chip 223 in the Y direction. Figure 16 shows an example of a table for setting the detection preparation time from the highest temperature in this embodiment, and is a table that replaces the example in Figure 15 of the second embodiment. This embodiment is also applicable to the first embodiment (Figure 13).

[0098] In the example shown in Figure 16, a detection preparation time is defined for each number of chip 223. Chip numbers 0 to 16 indicate the arrangement of each chip 223, with the chips 223 arranged in numerical order in the Y direction. Chip 223 with chip number 0 and chip number 16 are located at one end and the other end in the Y direction.

[0099] In this embodiment, the circulation device 218 supplies liquid to the discharge head 22 from one end in the Y direction of the discharge head 22 and discharges the liquid from the other end. Therefore, at the ends in the Y direction, the flow rate or velocity of the circulating liquid at chips 0 and 16 is smaller than at the other chips 223. Consequently, the viscosity reduction effect due to the circulating flow is low at these chips 223. Therefore, in the example in Figure 16, the detection preparation time for chips 0 and 16 is set to be longer than the detection preparation time for the other chip numbers. By setting a longer detection preparation time, the viscosity reduction effect at the maximum temperature can be obtained similarly at each chip 223.

[0100] <Fourth Embodiment> In the second embodiment, if the thickened liquid is difficult to eliminate by liquid circulation alone, the execution of pre-discharge is controlled as a recovery operation to restore discharge performance, but the execution of suction discharge may also be controlled. Suction discharge is an operation in which the recovery unit 17 forcibly sucks out the liquid in the discharge head 22 using negative pressure. Figures 17 and 184 are flowcharts showing an example of processing performed by the main control unit 111 in this embodiment, and are flowcharts of processing examples that replace the example in Figure 14.

[0101] In S41, the recording operation related to the recording job begins. The processes in S42 to S49 are repeatedly executed for each chip 223 during the recording operation.

[0102] In S42, temperature information of the nozzle 309 is acquired. In this embodiment, the temperature information is obtained from the detection results of each temperature sensor 225 of the chip 223. In S43, it is determined whether the highest temperature detected by each temperature sensor 225 of the chip 223 acquired in S22 is greater than or equal to the threshold T1. In this embodiment, the threshold T1 is 46°C. If the highest temperature is greater than or equal to the threshold T1, the process proceeds to S44; if it is less than the threshold T1, the process proceeds to S45.

[0103] In S44, it is determined whether the highest temperature detected by each temperature sensor 225 of the chip 223, acquired in S22, is greater than or equal to the threshold T2. The threshold T1 is a temperature higher than the threshold T2, and in this embodiment, it is 52°C. If the highest temperature is greater than or equal to the threshold T2, the process proceeds to S47; otherwise, the process proceeds to S46.

[0104] In S45, the pre-discharge flag, which determines whether or not to perform pre-discharge after the recording operation, and the suction flag, which determines whether or not to perform suction discharge after the recording operation, are both set to OFF, and the process proceeds to S48. The pre-discharge flag and suction flag are flags whose ON and OFF states are managed using, for example, the recording area of ​​RAM205. In S46, the pre-discharge flag is set to ON and the suction flag is set to OFF. In S47, the pre-discharge flag is set to OFF and the suction flag is set to ON.

[0105] In S48, a provisional detection preparation time W is set. In this embodiment, the detection preparation time W' is set from the highest temperature among the detection results of each temperature sensor 225 of the chip 223. The detection preparation time W' can be set using the table illustrated in Figure 15 or Figure 16. In S49, the provisional detection preparation time W' is set to 0.

[0106] In S50, the recording operation related to the recording job is completed. In S51, it is determined whether there are any chips 223 with the reserve ejection flag ON for each ejection head 22. For ejection heads 22 that contain chips 223 with the reserve ejection flag ON, the process proceeds to 52. For ejection heads 22 where all reserve ejection flags are OFF, the process proceeds to S53.

[0107] In S52, pre-discharge is performed on the discharge head 22, including the tip 223 with the pre-discharge flag ON, while the liquid is circulated by the circulation device 218. The nozzles 309 that are subject to pre-discharge are all nozzles 309 of the tip 223 with the pre-discharge flag set to ON. In S54, the pre-discharge time Wd required for the pre-discharge in S52 is calculated, and then the process proceeds to S55. In S53, the pre-discharge time Wd is set to 0 seconds.

[0108] In S55, it is determined whether there is a chip 223 with the suction flag ON for each discharge head 22. For discharge heads 22 that contain a chip 223 with the suction flag ON, the process proceeds to 56. For discharge heads 22 where all suction flags are OFF, the process proceeds to S57.

[0109] In S56, the discharge head 22, including the tip 223 with the suction flag ON, is suctioned and discharged by the recovery unit 17 while the liquid is circulated by the circulation device 218. The nozzles 309 targeted for suction and discharge are all nozzles 309 of the tip 223 with the suction flag set to ON. In S58, the suction time Ws required for the suction and discharge in S56 is calculated, and then the process proceeds to S59. In S57, the suction time Ws is set to 0 seconds.

[0110] In S59, a detection preparation time W is set for each discharge head 22. Here, first, a provisional detection preparation time Wmax is identified for each discharge head 22. In identifying the provisional detection preparation time Wmax, first, for each discharge head 22, the longest detection preparation time W' among the detection preparation times W' for each chip 223 set in S48 or S49 is identified. The identified longest detection preparation time W' is set as the provisional detection preparation time Wmax for that discharge head 22.

[0111] The detection preparation time W is calculated as W = Wmax - Wd - Ws. In the case of a discharge head 22 where preliminary discharge is performed, the time is removed because the liquid is circulated by the circulation device 218 during the preliminary discharge. Similarly, in the case of a discharge head 22 where suction discharge is performed, the time is removed because the liquid is circulated by the circulation device 218 during the suction discharge.

[0112] In S60, it is determined whether the detection preparation time W calculated for each discharge head 22 in S59 is W>0. If W>0, the process proceeds to S61; otherwise, the process proceeds to S62. In S61, each discharge head 22 waits for the detection preparation time W set in S59 while the liquid is circulated by the circulation device 218. Once the detection preparation time has elapsed, the process proceeds to S62. In S36, a discharge state detection process and a non-discharge determination process are performed for each discharge head 22. Here, liquid is discharged from each nozzle 306, and the non-discharge determination unit 219 identifies the nozzle 306 that is not discharging based on the detection result of the sensor 226.

[0113] As described above, in this embodiment, pre-discharge is performed on the nozzle 309 of the chip 223 whose temperature information indicates a temperature of threshold T1 or higher, and suction discharge is performed on the nozzle 309 of the chip 223 whose temperature indicates a temperature of threshold T2 or higher. Since the thickened liquid in the nozzle 309 that has thickened during the recording operation is discharged by pre-discharge or suction discharge, for example, the state of the nozzle 309 changes from the steady state in Figure 10(c) to the initial state in Figure 10(c), and the thickening is eliminated. Since the discharge state detection and non-discharge determination in S62 are performed with the thickening eliminated, the detection accuracy of non-discharging nozzles can be improved. In addition, while pre-discharge or suction discharge is being performed, the liquid is circulated by the circulation device 218 in the discharge head 22, so that time is excluded from the detection preparation time. Therefore, the thickening of the liquid in the nozzle 309 where pre-discharge or suction discharge is not performed is eliminated, and unnecessary detection preparation time can be reduced.

[0114] <Other Embodiments> In the above embodiment, a full line head was exemplified as the discharge head 22, but the present invention is also applicable to recording devices of other recording methods. For example, it is applicable to serial recording devices that repeatedly perform recording scanning, in which liquid is discharged while the discharge head moves in the main scanning direction, and intermittent transport of the recording medium.

[0115] Furthermore, the present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0116] <Summary of Embodiments> The above embodiments disclose the inventions of the following items.

[0117] Item 1. A dispensing means having a nozzle for dispensing liquid onto a recording medium, and a circulation means for circulating the liquid between the dispensing means and the liquid storage section containing the liquid, A detection means for detecting the liquid discharge state of the nozzle, An acquisition means for acquiring the temperature information of the nozzle, The system includes a setting means for setting a detection preparation time based on temperature information, during which the liquid is circulated by the circulation means between the end of the recording operation and the detection of the discharge state, when the discharge state is detected by the detection means after a recording operation in which the discharge means records to the recording medium. A recording device characterized by the following features.

[0118] Item 2. A recording device as described in item 1, The setting means is, If the temperature information indicates a first temperature, set the first time as the detection preparation time. If the temperature information indicates a second temperature that is higher than the first temperature, the detection preparation time is set to a second time that is longer than the first time. A recording device characterized by the following features.

[0119] Item 3. A recording device as described in item 1, The setting means is, The higher the temperature information indicates, the longer the detection preparation time is set. A recording device characterized by the following features.

[0120] Item 4. A recording device as described in any one of items 1 to 3, After a recording operation in which the discharge means records to the recording medium, when the detection means detects the discharge state, the system includes a recovery control means that performs a recovery operation to restore the discharge performance of the nozzle between the end of the recording operation and the detection of the discharge state, based on the temperature information. A recording device characterized by the following features.

[0121] Item 5. A recording device as described in item 4, The recovery control means is When the temperature information indicates a temperature above a threshold, the recovery operation is performed. A recording device characterized by the following features.

[0122] Item 6. A recording device as described in item 4 or item 5, The recovery operation is the operation of discharging the liquid from the nozzle. A recording device characterized by the following features.

[0123] Item 7. A recording device as described in item 4, The recovery control means is When the temperature information indicates a temperature above a first threshold, the first recovery operation is performed. If the temperature information indicates a temperature that is higher than or equal to a second threshold, which is higher than the first threshold, a second recovery operation is performed. A recording device characterized by the following features.

[0124] Item 8. A recording device as described in item 7, The system includes a recovery means for sucking the liquid from the nozzle, The first recovery operation is the operation of discharging the liquid from the nozzle, The second recovery operation is the operation of sucking the liquid from the nozzle by the recovery means. A recording device characterized by the following features.

[0125] Item 9. A recording device as described in any one of items 1 through 8, The dispensing means comprises a plurality of chips arranged in a predetermined direction, Each tip is equipped with multiple nozzles for dispensing the liquid, The acquisition means acquires the temperature information for each chip. A recording device characterized by the following features.

[0126] Item 10. A recording device as described in item 9, The setting means is, For each chip, according to its position in the predetermined direction, a temporary time for circulating the liquid by the circulation means is specified, and the detection preparation time of the discharge means is set based on the temporary time. A recording device characterized by the following features.

[0127] Item 11. A recording device as described in item 10, The circulation means circulates the liquid so that it flows in the predetermined direction in the discharge means. The setting means is, The longer the time for the chip closer to the end in the predetermined direction, A recording device characterized by the following features.

[0128] Item 12. A recording device as described in item 10 or item 11, The setting means sets the longest possible time as the detection preparation time for the discharge means. A recording device characterized by the following features.

[0129] Item 13. A recording device as described in item 9, The setting means is, The detection preparation time is set based on the highest temperature among the temperature information for each chip. A recording device characterized by the following features.

[0130] Item 14. A recording device as described in any one of items 9 through 13, The aforementioned dispensing means is a full line head, The predetermined direction is the longitudinal direction of the full line head. A recording device characterized by the following features.

[0131] Item 15. A recording device as described in any one of items 9 through 14, The detection means is a temperature sensor provided for each nozzle. A recording device characterized by the following features.

[0132] Item 16. A recording device as described in any one of items 9 through 14, The acquisition means acquires the detection result of the temperature sensor provided on the chip as temperature information. A recording device characterized by the following features.

[0133] Item 17. A dispensing means having a nozzle for dispensing liquid onto a recording medium, and a circulation means for circulating the liquid between the dispensing means and the liquid storage section containing the liquid, A detection means for detecting the liquid discharge state of the nozzle, A control method for a recording device equipped with, A step of acquiring temperature information of the nozzle, The system includes a setting step, in which, after a recording operation in which the discharge means records onto the recording medium, the detection means detects the discharge state, and the circulating means circulates the liquid between the end of the recording operation and the detection of the discharge state, the circulating means sets a detection preparation time based on the temperature information. A control method characterized by the following:

[0134] Item 18. A storage medium containing a program that causes a computer to execute the control method described in item 17.

[0135] Item 19. A program that causes a computer to execute the control method described in item 17.

[0136] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0137] 101 Recording device, 22 Discharge head, 111 Main control unit, 218 Circulation device, 225 Temperature sensor, 226 Sensor

Claims

1. A dispensing means having a nozzle for dispensing liquid onto a recording medium, and a circulation means for circulating the liquid between the dispensing means and the liquid storage section containing the liquid, A detection means for detecting the liquid discharge state of the nozzle, An acquisition means for acquiring the temperature information of the nozzle, The system includes a setting means for setting a detection preparation time based on temperature information, during which the liquid is circulated by the circulation means between the end of the recording operation and the detection of the discharge state, when the discharge state is detected by the detection means after a recording operation in which the discharge means records to the recording medium. A recording device characterized by the following features.

2. A recording device according to claim 1, The setting means is, If the temperature information indicates a first temperature, set the first time as the detection preparation time. If the temperature information indicates a second temperature that is higher than the first temperature, the detection preparation time is set to a second time that is longer than the first time. A recording device characterized by the following features.

3. A recording device according to claim 1, The setting means is, The higher the temperature information indicates, the longer the detection preparation time is set. A recording device characterized by the following features.

4. A recording device according to claim 1, After a recording operation in which the discharge means records to the recording medium, when the detection means detects the discharge state, the system includes a recovery control means that performs a recovery operation to restore the discharge performance of the nozzle between the end of the recording operation and the detection of the discharge state, based on the temperature information. A recording device characterized by the following features.

5. A recording device according to claim 4, The recovery control means is When the temperature information indicates a temperature above a threshold, the recovery operation is performed. A recording device characterized by the following features.

6. A recording device according to claim 4, The recovery operation is the operation of discharging the liquid from the nozzle. A recording device characterized by the following features.

7. A recording device according to claim 4, The recovery control means is When the temperature information indicates a temperature above a first threshold, the first recovery operation is performed. If the temperature information indicates a temperature that is higher than or equal to a second threshold, which is higher than the first threshold, a second recovery operation is performed. A recording device characterized by the following features.

8. A recording device according to claim 7, The system includes a recovery means for sucking the liquid from the nozzle, The first recovery operation is the operation of discharging the liquid from the nozzle, The second recovery operation is the operation of sucking the liquid from the nozzle by the recovery means. A recording device characterized by the following features.

9. A recording device according to claim 1, The dispensing means comprises a plurality of chips arranged in a predetermined direction, Each tip is equipped with multiple nozzles for dispensing the liquid, The acquisition means acquires the temperature information for each chip. A recording device characterized by the following features.

10. A recording device according to claim 9, The setting means is, For each chip, according to its position in the predetermined direction, a temporary time for circulating the liquid by the circulation means is specified, and the detection preparation time of the discharge means is set based on the temporary time. A recording device characterized by the following features.

11. A recording device according to claim 10, The circulation means circulates the liquid so that it flows in the predetermined direction in the discharge means. The setting means is, The longer the time for the chip closer to the end in the predetermined direction, A recording device characterized by the following features.

12. A recording device according to claim 10, The setting means sets the longest possible time as the detection preparation time for the discharge means. A recording device characterized by the following features.

13. A recording device according to claim 9, The setting means is, The detection preparation time is set based on the highest temperature among the temperature information for each chip. A recording device characterized by the following features.

14. A recording device according to claim 9, The aforementioned dispensing means is a full line head, The predetermined direction is the longitudinal direction of the full line head. A recording device characterized by the following features.

15. A recording device according to claim 9, The detection means is a temperature sensor provided for each nozzle. A recording device characterized by the following features.

16. A recording device according to claim 9, The acquisition means acquires the detection result of the temperature sensor provided on the chip as temperature information. A recording device characterized by the following features.

17. A dispensing means having a nozzle for dispensing liquid onto a recording medium, and a circulation means for circulating the liquid between the dispensing means and the liquid storage section containing the liquid, A detection means for detecting the liquid discharge state of the nozzle, A control method for a recording device equipped with, A step of acquiring temperature information of the nozzle, The system includes a setting step, in which, after a recording operation in which the discharge means records onto the recording medium, the detection means detects the discharge state, and the circulating means circulates the liquid between the end of the recording operation and the detection of the discharge state, the circulating means sets a detection preparation time based on the temperature information. A control method characterized by the following:

18. A storage medium storing a program that causes a computer to execute the control method described in claim 17.

19. A program that causes a computer to execute the control method described in claim 17.

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