Recording apparatus

Abstract

To improve detection accuracy of humidity near a discharge port.SOLUTION: According to an aspect of the present invention, a recording apparatus includes a moving unit configured to relatively move a recording medium and a discharge unit including a discharge port configured to discharge a liquid onto the recording medium, an air blowing unit configured to blow air to the discharge port, and a detection unit configured to detect humidity of the air.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a recording device. [Background technology]

[0002] When an ejection head that ejects liquid such as ink does not eject the liquid for a long period of time, the volatile components in the liquid evaporate from the ejection ports, causing the liquid to concentrate, and the concentration of solid components such as pigments increases. An increase in the liquid concentration can cause ejection defects. Therefore, a technique is known that ejects the liquid from the ejection head when it is estimated that the concentration has increased (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-8513 Summary of the Invention [Problem to be solved by the invention]

[0004] The humidity near the ejection orifice affects the evaporation of volatile components in the liquid. Detecting the humidity inside the printing device can improve the accuracy of estimating the concentration of solid components in the liquid. However, when liquid is ejected during printing, a humidity distribution occurs inside the printing device due to the influence of the moisture in the ejected liquid. This can result in a discrepancy between the detection result of the humidity sensor and the humidity near the ejection orifice.

[0005] The present invention provides a technique for improving the accuracy of detecting humidity near the ejection orifice. [Means for solving the problem]

[0006] According to the present invention, a moving means for relatively moving a recording medium and a discharging means having a discharge port for discharging a liquid onto the recording medium; a blowing means for blowing air to the discharge port; and a detection means for detecting the humidity of the air. A recording device is provided. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technique for improving the accuracy of detecting humidity near the ejection port. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a recording apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of a transport unit of the recording apparatus of FIG. [Figure 3] FIG. 2A is an explanatory diagram showing the configuration of a discharge head, and FIG. 2B is an explanatory diagram showing the configuration of a heater board. [Figure 4] (A) is a cross-sectional view of the discharge head, and (B) is an explanatory diagram of the circulation unit. [Figure 5] FIG. 4 is a diagram showing the position of the ejection head during a printing operation. [Figure 6] FIG. 4 is an explanatory diagram of capping of the ejection head. [Figure 7] FIG. 2 is a block diagram of a control unit of the recording apparatus of FIG. 1. [Figure 8] 10 is a flowchart showing an example of processing executed by a control unit. [Figure 9] 1A is a flowchart showing an example of processing executed by a control unit, and FIG. 1B is a diagram showing an example of a setting table for evaporation rates. [Figure 10] 10 is a flowchart showing an example of processing executed by a control unit. [Figure 11] 10(A) to 10(C) are diagrams showing examples of data used in processing. [Figure 12] FIG. 10 is a diagram showing another example of the arrangement of the blower unit. [Figure 13] FIG. 10 is a diagram showing another example of the arrangement of the humidity sensor. [Figure 14] FIG. 10 is a diagram showing another example of the arrangement of the air blowing unit and the humidity sensor. [Figure 15]10A is a diagram showing another example of the configuration of the transport unit, and FIG. 10B is a diagram showing an example of application to a serial type recording apparatus. [Figure 16] FIG. 10 is a diagram showing another example of an ink discharge portion. DETAILED DESCRIPTION OF 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 scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] First Embodiment <Configuration of recording device> FIG. 1 is a schematic diagram of a recording apparatus 1 according to one embodiment of the present invention. The recording apparatus 1 is an apparatus that records an image by ejecting liquid ink onto a recording medium 100. In the figure, arrows X, Y, and Z indicate directions that intersect with each other, and the X direction and Y direction are horizontal directions that are perpendicular to each other. The Z direction is the up-down direction. In this embodiment, the X direction, Y direction, and Z direction indicate the overall length direction, depth direction, and height direction of the recording apparatus 1, respectively.

[0011] "Recording" not only includes the formation of meaningful information such as characters and figures, but also includes the formation of images, patterns, designs, etc. on a recording medium, whether meaningful or insignificant, or the processing of the medium, regardless of whether it is manifested in a way that can be perceived visually by humans. In addition, although sheet-like paper is assumed as the "recording medium" in this embodiment, it may also be cloth, plastic film, etc.

[0012] The recording apparatus 1 includes a feeding device 14, an image forming device 15, and a collection device 18. The feeding device 14 is a device that feeds recording media 100 to the image forming device 15. The feeding device 14 includes a stacking section 14a on which a plurality of recording media 100 before recording is stacked, and a transport mechanism 14b. In the present embodiment, a plurality of stacking sections 14a are provided, and a transport mechanism 14b is provided for each stacking section 14a. The transport mechanism 14b includes a pair of rollers that sandwich and transport the recording media 100.

[0013] The recovery device 18 is a device that recovers recorded recording media 100 that are discharged from the image forming device 15. The recovery device 18 includes a stacking section 18a on which a plurality of recording media 100, which are recorded products, are stacked, and a transport mechanism 18b. The transport mechanism 18b includes a pair of rollers that sandwich and transport the recording media 100.

[0014] The image forming apparatus 15 includes a transport unit 17 that transports the recording medium 100 in the X direction, a plurality of ejection heads 11a to 11d that eject liquid onto the recording medium 100, and lifting units 13a to 13d that raise and lower the ejection heads 11a to 11d. When the ejection heads 11a to 11d are referred to collectively or when there is no need to distinguish between the individual ejection heads 11a to 11d, they will be simply referred to as ejection heads 11. Similarly, when the lifting units 13a to 13d are referred to collectively or when there is no need to distinguish between the individual lifting units 13a to 13d, they will be simply referred to as lifting unit 13.

[0015] In addition to FIG. 1, please also refer to FIG. 2. FIG. 2 is a plan view of the transport unit 17. The transport unit 17 is an example of a movement mechanism that moves the ejection head 11 and the recording medium 100 relative to each other. In this example, the transport unit 17 moves the recording medium 100 relative to the stationary ejection head 11, thereby moving the two relatively. The transport unit 17 includes an endless transport belt 17, a plurality of rollers 17b that move the transport belt 17, and a suction device 17c. The plurality of rollers 17b are rotated around an axis in the Y direction by a drive source (e.g., a motor) not shown. The transport belt 17a moves cyclically counterclockwise as viewed in FIG. 1 due to the rotation of the plurality of rollers 17b.

[0016] The conveyor belt 17a can be made of a material such as resin or metal. The conveyor belt 17a is a conveyor medium for the recording medium 100, and travels in the X direction with the recording medium 100 placed on it in a portion of its travel section (referred to as the conveying section or the recording section). The conveyor belt 17a faces the lower surface of the ejection head 11 (the ejection port surface 110, which will be described later) in the transport section.

[0017] A large number of holes H are formed in the conveyor belt 17 at a predetermined pitch. The suction device 17c is equipped with, for example, an electric fan and is located below the conveyor belt 17 in the conveying section, generating an airflow that flows from above to downstream in the Z direction. Air is sucked through the large number of holes H in the conveyor belt 17 in the conveying section by the action of the suction device 17c. As a result, the recording medium 100 is conveyed while being adsorbed to the conveyor belt 17 in the conveying section, and the conveying behavior of the recording medium 100 can be stabilized. The suction air pressure can be, for example, -500 Pa. The conveying speed can be, for example, 0.5 m / s.

[0018] In this embodiment, the recording medium 100 is conveyed by suction using air suction, but it may also be conveyed by suction using static electricity. Also, a unit having a function of drying or cooling the recording medium 100 may be added to the conveying unit 17.

[0019] The ejection head 11 is a recording head that ejects liquid onto the recording medium 100 to record an image. The ejection head 11 is a full-line type head that extends in the width direction (Y direction) of the recording medium 100, and has liquid ejection ports arranged across a range that covers the width of the largest usable size recording medium 100. FIG. 2 shows an example of the width Wa of a medium-sized recording medium 100. The effective length (e.g., 368 mm) of the ejection port array of the ejection head 11 is contained within the width Wb (e.g., 380 mm) of the conveyor belt 17a.

[0020] The ejection heads 11a to 11d are arranged in a line from upstream to downstream in the transport direction of the recording medium 100. The ejection heads 11a to 11d eject different types of ink. For example, the ejection heads 11a to 11d eject four types of ink, namely, yellow ink, magenta ink, cyan ink, and black ink, in that order. These four types of ink are sometimes called basic color inks. Note that the type and number of inks and the order of ejection in the transport direction of the recording medium 100 (the arrangement order of the ejection heads 11a to 11d) are not limited to this.

[0021] The configuration of the ejection head 11 will be described with reference to Figures 3(A) and 3(B). Figure 3(A) is an explanatory diagram showing the configuration of the ejection head 11, and Figure 3(B) is an explanatory diagram of the heater boards. As shown in Figure 3(A), the ejection head 11 is provided with, as an example, 17 heater boards (printing element substrates) HB0 to HB16. Figure 3(B) shows an example of the configuration of heater board HB0, and the other heater boards HB1 to HB16 have a similar configuration.

[0022] The heater board HB0 has an ejection port array in which multiple ejection ports OP are aligned in the Y direction. The ejection port arrays are spaced apart in the X direction and are arranged in multiple rows (four rows in the example shown). The heater board HB0 also has a temperature sensor SR and a sub-heater SH, which is a heating element. When voltage is applied to the sub-heater SH, the sub-heater SH generates heat and heats the substrate of the heater board HB0, which then heats the ink near the substrate. By adjusting the ink temperature in advance using the sub-heater SH, ink can be ejected efficiently during ink ejection. The heater board HB0 is divided into 4 x 4 = 16 sections, with one sub-heater SH provided in each section. This makes it possible to heat the heater board HB0 on ​​a section-by-section basis.

[0023] The temperature sensor SR is a sensor for detecting the temperature of the heater board HB0. In this embodiment, the ink temperature can be set to a desired temperature by controlling the application of drive pulses to the sub-heater SH based on the temperature detected by the temperature sensor SR during and before printing.

[0024] 3A, the heater boards HB0 to HB16 are arranged in a staggered pattern so that the ends of the nozzle rows of adjacent heater boards overlap in the X direction. The lower surface of each ejection head 11 forms an ejection port surface 110 on which such an ejection port row is formed. Note that the ejection head 11 does not have to be configured with multiple heater boards HB0 to HB16, and may instead be configured with a single heater board having a long ejection port row in the Y direction.

[0025] 4A is an XZ cross-sectional view of the periphery of one ejection orifice OP. The ejection orifice OP is connected to an individual flow path 113 for each ejection orifice OP, and the individual flow path 113 is provided with a printing element 114 for each ejection orifice OP. This printing element 114 is, for example, an electro-thermal conversion element, and generates thermal energy when a drive pulse is applied. The generated thermal energy causes ink to bubble, and the ink is ejected from the corresponding ejection orifice OP. Note that the printing element 114 may be an electro-thermal conversion element, a piezoelectric element, an electrostatic element, or a MEMS element.

[0026] Ink flows in the individual flow paths 113 in the direction indicated by the arrows in Fig. 4(A). In this embodiment, ink is circulated and supplied to the ejection head 11. Fig. 4(B) is an explanatory diagram of a circulation unit 12 that circulates ink.

[0027] The recording device 1 includes a main tank 16, a sub-tank 120, and a circulation unit 12 for each ejection head 11. The main tank 16 and the sub-tank 120 are liquid containers that contain the ink to be ejected by the corresponding ejection head 11. For example, the main tank 16 and the sub-tank 120 that correspond to the ejection head 11a contain orange ink. When the pump P0 is driven, ink is supplied from the main tank 16 to the sub-tank 120. When a predetermined amount of ink has been supplied from the main tank 16 to the sub-tank 120, the ink supply is stopped, and ink is supplied again when the remaining ink in the sub-tank 120 becomes low, for example.

[0028] The circulation unit 12 includes pumps P1 and P2 and a pressure regulator 121. The pump P1 pumps ink from the sub-tank 120 to the pressure regulator 121 via a pipe 122. The pressure regulator 121 applies a pressure difference to the supplied ink and sends it to the ejection head 11. Ink on the relatively high pressure side is sent via a pipe 123, and ink on the low pressure side is sent via a pipe 124.

[0029] The ejection head 11 has common flow paths 111 and 112. The common flow path 111 is connected to a pipe 123 and is supplied with high-pressure ink. One end of the common flow path 112 is connected to a pipe 124 and is supplied with low-pressure ink. Each individual flow path 113 is connected between the common flow path 111 and the common flow path 112. Ink flows from the common flow path 111 through the individual flow paths 113 to the common flow path 112.

[0030] The other end of the common flow path 112 is connected to a pipe 125. The pump P2 pumps ink from the common flow path 112 to the subtank 120 via pipes 125 and 126. In this way, ink is circulated between the subtank 120 and the ejection head 11.

[0031] The lifting unit 13 will be described with reference to Figures 1 and 5. Figure 5 is a diagram showing an example of the height of the ejection head 11 during a recording operation.

[0032] The lifting unit 13 is a mechanism for changing the height from the surface of the recording medium 100 to the ejection port surface 110 of the ejection head 11 in the transport section of the transport belt 17a. In this embodiment, the height from the surface of the recording medium 100 to the ejection port surface 110 of the ejection head 11 is changed by lifting and lowering the ejection head 11, but the height may also be changed by lifting and lowering the transport unit 17.

[0033] A lifting unit 13 is provided for each discharge head 11, and the position of each discharge head 11 in the Z direction can be changed for each discharge head. For example, the lifting unit 13a lifts and lowers the discharge head 11a to change its position in the Z direction. In this embodiment, each discharge head 11 can be lifted and lowered individually, but multiple discharge heads 11 may be lifted and lowered by a single lifting unit 13. In this case, the positions of the multiple discharge heads 11 lifted and lowered by a single lifting unit 13 in the Z direction are changed in common. The lifting unit 13 includes, for example, a drive source such as a motor, and an operating mechanism that moves the discharge heads 11 using the driving force of the drive source. The operating mechanism is, for example, a ball screw mechanism, a belt transmission mechanism, a link mechanism, or the like.

[0034] During a recording operation, each ejection head 11 is positioned at a position (referred to as a recording position) where the height of the ejection port surface 110 relative to the surface of the recording medium 100 is height h1. Height h1 is a very small gap (for example, on the order of a few millimeters).

[0035] While waiting for a recording job to be executed, the ejection heads 11 may be moved to a retracted position and capped. Figure 6 shows an example of this. The ejection port surface 110 of each ejection head 11 is capped with a cap member 10. During capping, each ejection head 11 is moved to the retracted position by the lifting unit 13. The retracted position is a position where the height of the ejection port surface 110 relative to the surface of the recording medium 100 is h2, which is higher than height h1.

[0036] The cap member 10 is moved by a moving mechanism (not shown) between a capping position C1, which covers the ejection port surface 110, and a retracted position C2, which does not cover the ejection port surface 110, as shown in FIG. 6. The capping prevents the liquid component of the ink from evaporating from the ejection ports OP during standby (standby when not printing). Upon receiving a printing command, the cap member 10 moves from the capping position C1 to the retracted position C2, thereby canceling the capping state. The lifting unit 13 is then driven to lower the ejection head 11 to the printing position. The transport unit 17 then starts transporting the recording medium 100. An image is recorded on the recording medium 100 by synchronizing the timing of the recording medium 100 passing under the ejection head 11 with the timing of ink ejection. After the image is printed, the ejection head 11 is again raised to the retracted position, and capping is performed.

[0037] The ejection head 11 may be retracted and capped to perform an ejection performance recovery operation. As an example, a suction recovery operation may be performed in which ink is sucked from the ejection orifices OP of the ejection head 11. FIG. 6 shows an example in which ink is sucked from the ejection orifices OP of the ejection head 11 via the cap member 10 and piping using the pump P3, and then discharged into a waste liquid tank. In addition to this suction recovery operation, a preliminary ejection operation may also be used as an ejection performance recovery operation. In the preliminary ejection operation, ink is ejected from the ejection orifices OP of the ejection head 11. The destination of the ejection is, for example, the cap member 10.

[0038] <Blower unit and humidity sensor> Referring to FIG. 1, blower units 151a and 151b are provided on the top of a housing 150 that forms the outer wall of the image forming apparatus 15. The blower units 151a and 151b are electric fans that are positioned higher than the ejection heads 11 and blow air from outside the image forming apparatus 15 toward the ejection heads 11. The blower units 151a and 151b have the wind power to blow air toward the ejection ports OP of the ejection port surface 110. Arrow D1 indicates the path and direction of the airflow generated by the blower units 151a and 151b. The airflow is blown toward the top of the ejection head 11, flows downward through the gaps between adjacent ejection heads 11, and reaches the ejection port surface 110. By blowing air toward the ejection ports OP, the humidity of the air near the ejection ports OP can be stabilized.

[0039] The air blowing units 151a and 151b may have an output that generates an airflow stronger than the airflow generated by the conveyor belt 17a of the conveyor unit 17 or the conveyance of the recording medium 100. For example, the flow velocity of the airflow blown by the air blowing units 151a and 151b may be faster than the relative movement speed between the recording medium 100 and the ejection head 11. In this embodiment, this relative movement speed is the conveyance speed of the recording medium 100. Therefore, the flow velocity of the airflow blown by the air blowing units 151a and 151b may be faster than the conveyance speed of the recording medium 100. This allows the air blowing units 151a and 151b to more reliably blow air to the outlets OP of the ejection outlet surface 110.

[0040] If the air blown by the air blowing units 151a and 151b covers the entire width of the outlet surface 110 of the ejection head 11 in the Y and X directions, the humidity around all of the outlets OP can be stabilized. Therefore, the number of blowing units 151a and 151b is not limited to two, and three or more may be installed as necessary. In this case, for example, axial flow square fans may be arranged in a matrix in the X and Y directions. For example, a total of eight square fans may be arranged in two rows in the X direction and four rows in the Y direction.

[0041] A humidity sensor 153 is provided within the housing 150. The humidity sensor 153 is supported by a support plate 152. The support plate 152 is fixed to the top of the housing 150 and extends downward. The humidity sensor 153 measures the humidity of the air blown from the air blowing units 151a and 151b (particularly the air blowing unit 151b). In this embodiment, one humidity sensor 153 is provided, but multiple humidity sensors 153 may be installed at intervals in the Y direction, in which case the humidity may be the average value of the detection results of the multiple humidity sensors 153.

[0042] The humidity sensor 153 of this embodiment is intended to measure the humidity of the air near the ejection orifices OP to use as a parameter for estimating the ink concentration, as will be described later. However, the humidity sensor 153 is installed at a position away from the vicinity of the ejection orifices OP, and is designed to measure the humidity of the air in the blower units 151a and 151b. The reason for this will be explained below.

[0043] The location of the humidity sensor 153 can also be considered on the transport path of the recording medium 100. If the humidity sensor 153 is installed on the transport path of the recording medium 100, it must be located at a certain height so that the recording medium 100 does not come into contact with the humidity sensor 153. In this case, high-humidity air generated by the ejection of ink from the ejection head 11 during a printing operation reaches the position of the humidity sensor 153 arranged on the transport path by convection and diffusion. However, compared to this high humidity, the humidity of the recording medium 100 being transported at the same time is low, so the humidity of the air flowing near the ejection openings OP of the ejection head 11 may be lower than the humidity detected by the humidity sensor 153. As a result, during a printing operation, the correlation between the detection result of the humidity sensor 153 and the actual humidity near the ejection openings OP may be lost, which may result in inaccurate concentration estimation, as described below.

[0044] It is also conceivable to install the humidity sensor 153 on the ejection head 11 itself. However, if the humidity sensor 153 is installed on the ejection head 11 without providing a mechanism for controlling airflow near the ejection openings OP, as with the sending units 151a and 151b, this could cause the humidity sensor to malfunction. Specifically, fine ink mist generated by the printing operation is stirred up by convection and adsorbed onto the humidity sensor 153. As a result, the humidity sensor 153 may malfunction (measurement value may be offset). Furthermore, in this embodiment, the ejection head 11 is raised and lowered by the lifting unit 13. Installing the humidity sensor 153 on the ejection head 11 also poses a disadvantage in terms of wiring the sensor cable.

[0045] Simply placing the humidity sensor 153 at a position far from the ejection opening OP in order to mitigate the effects of ink mist may result in the same results as when the humidity sensor 153 is placed on the transport path of the recording medium 100. In other words, the humidity of the air flowing into the vicinity of the ejection opening OP of the ejection head 11 may be lower than the detection result of the humidity sensor 153, which may disrupt the correlation between the two.

[0046] For the above reasons, in this embodiment, the humidity sensor 153 is arranged at a position away from the vicinity of the outlet OP of the ejection head 11, and is configured to detect the humidity of the air blown to the outlet OP. In particular, in the configuration example of Fig. 1, the temperature sensor 153 is arranged downstream of the blower units 151a and 151b and upstream of the ejection head 11 in the flow direction of the air current generated by the blower units 151a and 151b.

[0047] <Control unit> 7 is a block diagram of the control unit 2 of the recording device 1. The control unit 2 includes a printer control unit 20 that controls the recording process. The printer control unit 20 includes a CPU 21 that controls the entire recording device 1, and a ROM 22 and RAM 23 for storing control programs executed by the CPU 21 and various data. An integrated circuit (Application Specific Integrated Circuit: ASIC) 24 incorporates a network controller, a serial IF controller, a head data generation controller, a motor controller, etc. The head control unit 25 generates final ejection data and drive voltages for ejection by the ejection head 11, and controls the elevation of the ejection head 11, etc.

[0048] The control unit 2 also includes a communication unit 26 that receives print jobs including print data from an external print server or an external PC, an operation control unit 27 that controls an operation panel that accepts user input, and a recording medium transport control unit 28 that controls the transport of the recording medium 100. The control unit 2 also includes a concentration control unit 29 that controls an adjustment operation to adjust the concentration of solid components in the ink circulated by the circulation unit 12. Each control unit includes at least one processor and at least one storage device that stores a program executed by the processor. The storage device is, for example, a semiconductor memory.

[0049] <Adjusting the concentration of circulating ink> The ink in the ejection head 11 increases in concentration as volatile components evaporate from the ejection orifices OP. Solid components include, for example, colorants (pigments) and resins. An increase in the concentration of solid components can cause ejection defects. Therefore, an adjustment operation is performed to adjust the concentration of circulating ink for each type of ink. In this embodiment, the adjustment operation is an operation to discharge ink from the ejection head 11. The concentration of solid components in circulating ink varies, and the concentration is often high for the ink in the ejection head 11. Discharging ink from the ejection head 11 can reduce the concentration of solid components in circulating ink. The operation to discharge ink from the ejection head 11 may involve discharging ink from the ejection head 11, or may involve suction via the cap member 10 using the pump P3 illustrated in FIG. 6. The adjustment operation may also include an operation to drive the pump P0 to refill ink from the main tank 16 to the subtank 120 in addition to discharging ink from the ejection head 11. Circulating ink with a high concentration of solid components can be diluted with fresh ink from the main tank 16.

[0050] When ink in the ejection head 11 is discharged as a result of the adjustment operation, the amount of waste ink increases. It is desirable to minimize unnecessary ink consumption. To achieve this, it is necessary to improve the accuracy of estimating the concentration of solid components. An example of the processing performed by the control unit 2 in relation to the adjustment operation of the concentration of solid components will be described. In this embodiment, the concentration of solid components is estimated, and adjustment operation is performed based on the estimation result. These processes can be performed at predetermined timings based on the passage of time, the amount of printing job executed, the amount of ink ejected, etc. In the following example, these processes are performed after the end of the printing operation for each execution of a printing job.

[0051] 8 is a flowchart showing an example of a process for estimating the concentration of solid components, which is executed by the concentration control unit 29. The concentration of solid components is estimated for each type of ink (i.e., for each ejection head 11), and here, pigments are assumed to be the solid components.

[0052] In step S1, it is determined whether or not there is an execution command for a recording job (recording command). If there is no recording command, the process ends. If there is a recording command, the process proceeds to step S2. In step S2, the current concentration estimate value (previous estimation result value) N x Load the concentration estimate N x is stored in the storage device of the concentration control unit 29, for example, and is updated based on the estimation result of the process in FIG. 8. Note that FIG. 11(A) shows the concentration estimation value N x The initial value of N ref This is an example of setting the initial value N ref is the pigment concentration in the fresh ink, and is stored in the storage device of the concentration control unit 29, for example.

[0053] In step S3, it is determined whether the printing operation has ended. If it is determined that the printing operation has ended, the process proceeds to step S4. In step S4, the evaporation amount V and the consumed ink amount (cumulative value) I are calculated. n , and circulating ink amount J n The evaporation amount V will be described later with reference to FIG. 9A. The circulating ink amount J n is the initial value of the amount of ink in the circulation path, and is set in advance based on the specifications of the circulation path. Figure 11(B) shows an example.

[0054] Ink consumption I n is the cumulative value of the amount of ink ejected in the printing operations up to now, and is mainly affected by the printing operation content of each printing job. The amount of ink ejected in a printing operation is calculated, for example, from the count value of the number of pixels in the printed image corresponding to the type of ink. For example, it can be calculated by multiplying the count value by the ejection amount of one ejection (for example, 2.0 [ng]). The amount of ink consumed in the current printing operation I c Plus, I n+1 I n+1 =I n +I c , and is calculated as follows.

[0055] In step S5, the current active estimate N x+1is calculated. This value is N x+1 ={N x ×(J n -I n )} / (J n -I n+1 -V) It is calculated as follows.

[0056] In step S6, the concentration estimate N x , Ink consumption I n But the value N x+1 , I n+1 The process is now complete. In this way, the estimated concentration value N x By updating the value, the pigment concentration of the ink in the circulation path can be managed.

[0057] The evaporation amount V obtained in step S4 of Fig. 8 is calculated from the evaporation rate of ink set at the ejection port OP. Fig. 9(A) shows the calculation flow for the evaporation amount V obtained in step S4 of Fig. 8. Fig. 9(B) is a table referenced to change the evaporation rate according to the head temperature and humidity.

[0058] In step S11, acquisition of the temperature of the temperature sensor SR is started. The detection results of the temperature sensor SR are sampled by the head control unit 25 for each of the heater boards HB0 to HB16 at intervals of 100 milliseconds.

[0059] In step S12, humidity measurement is started by the humidity sensor 153. Next, in step S13, the recording time T is calculated. The recording time T is the time (in seconds) from when the recording command is received and the cap 10 is opened (time T0), until the ejection head 11 is lowered from the retracted position to the recording position at height h1, the recording operation ends, and capping is completed again (time T1) (T=T1-T0). This recording time T can be calculated by measuring.

[0060] In step S14, the average value of the temperature for each of the heater boards HB0 to HB16 during the recording time T is calculated, and further the average value of the temperatures of the 17 heater boards HB0 to HB16 is calculated. In step S15, the average value of the detection result (humidity) of the humidity sensor 153 during the recording time T is calculated. The humidity is calculated as weight absolute humidity (unit: kg / kg Dry Air).

[0061] In step S16, the evaporation rate Vr is set by referring to the table. At this time, the evaporation rate value is set according to the average values ​​of the temperature and humidity calculated in steps S14 and S15. FIG. 9(B) shows an example of the evaporation rate setting table. The evaporation rate Vr is the rate per outlet OP and is specified in [ng / s] units. When the humidity is in range H1 and the temperature is in range T1, the evaporation rate Vr is 14 [ng / s].

[0062] The ranges for each range are as follows:

[0063] Range H1: Humidity <0.004 Range H2: 0.004≦Humidity<0.007 Range H3: 0.007≦Humidity<0.010 Range H4: 0.010≦Humidity<0.013 Range H5: 0.013≦Humidity Range T1: Temperature < 35℃ Range T2: 35℃≦Temperature<40℃ Range T3: 40℃≦ temperature In step S17, the evaporation amount V is calculated. The evaporation amount V is expressed as follows: V = Vr × T × N Here, N is the number of ejection openings OP. For example, if each of the heater boards HB0 to HB16 has 2048 ejection openings OP in 512 x 4 rows, the total number of ejection openings OP per print head 11 is 34816. The evaporation amount is estimated from the above.

[0064] 10 is a flowchart showing an example of a process related to the execution of the adjustment operation, which is a concentration determination process executed following the process of FIG. 8. In step S21, the concentration estimated value N x is a predetermined upper limit N max It is determined whether the upper limit N (predetermined density) is exceeded. max An example of the upper limit value N max is set for each type of ink and is stored in a storage device of the density control unit 29, for example.

[0065] Returning to Figure 10, the concentration estimate N x is the upper limit N max If it does not exceed the density, the process ends, and if it does exceed the density, the process proceeds to step S22. In step S22, an adjustment operation is performed. As described above, the adjustment operation includes the operation of discharging ink from the ejection head 11. At that time, the density estimated value N x The higher the value, the more ink may be discharged. The discharge amount may be increased by increasing the amount discharged in one cycle or by increasing the number of discharges. In step S23, the ink consumption amount I is increased by the amount of ink discharged in step S22. n This completes the process.

[0066] In this way, in this embodiment, the detection result of the humidity sensor 153, which has a correlation with the actual humidity near the ejection opening OP, is used to improve the accuracy of estimating the concentration of the solid component of the ink. As a result, it is possible to prevent ink from being wasted during the adjustment operation and reduce the amount of ink consumed.

[0067] Second Embodiment In this embodiment, a configuration example in which blower units are provided at multiple positions will be described. FIG. 12 is a schematic diagram of a recording apparatus 1 according to this embodiment. In the example of FIG. 12, blower units 154a to 154d are installed on the side (one side in the X direction) of the corresponding ejection heads 11a to 11d. The blower units 154a to 154d are electric fans that generate airflow downward in the Z direction. Arrow D2 indicates the path and direction of the airflow generated by the blower units 154a to 154d. The airflow passes downward between adjacent ejection heads 11 and reaches the ejection port surface 110. The airflow indicated by arrow D2 includes air from the blower units 151a and 151b. By blowing air to the ejection port OP, the humidity of the air near the ejection port OP can be stabilized.

[0068] Humidity sensor 153 is located downstream of fan units 151a and 151b and upstream of fan units 154a to 154d. Humidity sensor 153 detects the humidity of the air sucked in by fan units 154a to 154d. With this arrangement, the humidity of the air sent from fan units 151a and 151b is detected, and the air whose humidity has been detected is more reliably delivered to the vicinity of outlet OP by fan units 154a to 154d.

[0069] The configuration of this embodiment is advantageous in that it makes it easier for air to reach the vicinity of the ejection port OP in an apparatus that needs to narrow the distance in the X direction between adjacent ejection heads 11 due to space constraints, etc. Furthermore, it has the effect of increasing the correlation between the detection result of the humidity sensor 153 and the actual humidity near the ejection port OP.

[0070] Third Embodiment In this embodiment, a humidity sensor is disposed between adjacent ejection heads 11. Fig. 13 is a schematic diagram of a recording apparatus 1 according to this embodiment showing an example thereof. In the example of Fig. 13, humidity sensors 154a to 154d are installed on the side (one side in the X direction) of the corresponding ejection heads 11a to 11d. Each of the humidity sensors 154a to 154d is disposed at a predetermined distance (for example, 100 mm) from the ejection port surface 110 of the corresponding ejection head.

[0071] In this embodiment, as in the second embodiment, air blowing units 154a to 154d are arranged on the sides of the ejection heads 11a to 11d. Each humidity sensor 154a to 154d is located downstream of the corresponding air blowing unit 154a to 154d. On the other hand, air blowing units 151a and 151b are not provided.

[0072] Air is blown near the outlet OP by the air blowing units 154a to 154d, and the humidity of the air can be detected by the humidity sensors 154a to 154d, which has the effect of increasing the correlation between the detection results of the humidity sensors 154a to 154d and the actual humidity near the outlet OP.

[0073] In this embodiment, an example in which the blower units 151a and 151b are not provided has been described, but a configuration in which these are provided may also be used.

[0074] <Fourth embodiment> The air blowing unit may be configured to blow air from the side of the ejection port OP. Figure 14 is a schematic diagram of the recording apparatus 1 according to this embodiment. The air blowing unit 157 is configured to blow air from the side (from the side in the X direction) of the ejection head 11, rather than at a position where it takes in outside air. The air blowing unit 157 is an electric fan supported by a support plate 156 fixed to the housing 150. The air blowing unit 157 generates an air current in the direction of arrow D3.

[0075] In order to direct the airflow generated by the blower unit 157 intensively toward the vicinity of the discharge port OP, a guide plate 158 is provided around the blower unit 157. The airflow generated by the blower unit 157 is guided by the guide plate 158 to flow toward the vicinity of the discharge port OP.

[0076] The humidity sensor 159 is installed on the support plate 156a downstream of the blower unit 157. The humidity sensor 159 can detect the humidity of the air blown by the blower unit 157. The air blown from the blower unit 157 flows between the outlet surface 110 of the ejection head 11 and the conveyor belt 17a, which has the effect of increasing the correlation between the detection result of the humidity sensor 159 and the humidity near the ejection outlet OP.

[0077] In this embodiment, the air blowing unit 157 is configured to blow air from the upstream side to the downstream side in the transport direction of the recording medium 100 (from right to left in the X direction in FIG. 14). This is because the airflow generated by the transport of the recording medium 100 also flows from the upstream side to the downstream side in the transport direction, and the direction of the air blown by the air blowing unit 157 must be aligned with this airflow. By aligning the airflow direction with the transport direction of the recording medium 100, it becomes easier to cause the air from the air blowing unit 157 to flow between adjacent ejection heads 11, where the humidity is detected by the humidity sensor 159.

[0078] Fifth Embodiment In the above embodiment, the detection result of the humidity sensor is used to estimate the ink concentration, but the detection result of the humidity sensor can also be used for other purposes, such as changing the ink ejection amount or the transport speed of the recording medium 100 depending on the detection result of the humidity sensor.

[0079] Sixth Embodiment In the above embodiment, a conveyor belt-type conveying mechanism is exemplified as the conveying unit 17, but a roller-type conveying mechanism may also be used. FIG. 15(A) is a schematic diagram showing one example. For simplicity of explanation, only one ejection head 11 is shown. A roller pair 17d is disposed upstream of the ejection head 11 in the conveying direction of the recording medium 100, and a roller pair 17e is disposed downstream. The roller pair 17d conveys the recording medium 100 by rotating while sandwiching the recording medium 100. Similarly, the roller pair 17e also conveys the recording medium 100 by rotating while sandwiching the recording medium 100.

[0080] Seventh Embodiment In the above embodiment, a full-line head was used as the ejection head 11, but the present invention can also be applied to a serial-type recording device. Figure 15(B) is a schematic diagram showing an example. Multiple ejection heads 11' are mounted on a carriage CR, and the carriage CR is reciprocated by a scanning mechanism DR in the direction across the recording medium 100 (Y direction).

[0081] The scanning mechanism DR is, for example, a belt transmission mechanism, and includes a pair of pulleys spaced apart in the Y direction, an endless belt wound around the pair of pulleys, and a motor that rotates the pulleys. The carriage CR is fixed to the endless belt, and the carriage CR is moved by driving the motor to run the endless belt. The scanning mechanism DR is an example of a movement mechanism that moves the ejection head 11' and the recording medium 100 relative to each other.

[0082] In the example of Figure 15(B), the recording medium 100 is transported by a roller-type transport mechanism, as in the sixth embodiment. However, a transport belt-type transport mechanism, as in the first embodiment, may also be used. An image is recorded by alternately repeating a transport operation (intermittent transport operation) in which each pair of rollers 17d, 17e transports the recording medium 100 a predetermined amount in the X direction and a recording scan while transport is stopped. A recording scan is an operation in which ink is ejected from the ejection head 11' while moving the carriage CR on which the ejection head 11' is mounted.

[0083] Eighth Embodiment In the above embodiment, the discharge of ink from the ejection heads 11 and 11' was exemplified as an adjustment operation for adjusting the concentration of solid components in the ink circulated by the circulation unit 12. However, ink may be discharged from another location in the ink circulation path. FIG. 16 shows one such example. In the example shown in the figure, a pump P4 is provided in the pipe 125 between the ejection head 11 and the pump P2 to discharge ink into a waste tank. The pump P4 can discharge concentrated ink at a position downstream of the ejection head 11 in the flow direction of the circulating ink flow.

[0084] <Other embodiments> The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0085] <Summary of the embodiment> The above embodiments disclose at least the following recording devices.

[0086] Item 1. a moving means for relatively moving a recording medium and a discharging means having a discharge port for discharging a liquid onto the recording medium; a blowing means for blowing air to the discharge port; and a detection means for detecting the humidity of the air. A recording device characterized by:

[0087] Item 2. a moving means for relatively moving a recording medium and a discharging means having a discharge port for discharging a liquid onto the recording medium; a blowing means for blowing air to the discharge port; a detection means for detecting humidity, The detection means is disposed on a path of the airflow generated by the blowing means. A recording device characterized by:

[0088] Item 3. Item 2. The recording device according to item 2, The detection means is disposed downstream of the blowing means in the direction of the airflow. A recording device characterized by:

[0089] Item 4. Item 2. The recording device according to item 2, The detection means is disposed upstream of the blowing means in the direction of the airflow. A recording device characterized by:

[0090] Item 5. Item 4. The recording device according to any one of items 1 to 4, a flow velocity of the airflow blown by the blowing means is faster than a relative movement velocity between the recording medium and the ejection means; A recording device characterized by:

[0091] Item 6. Item 5. The recording device according to any one of items 1 to 5, a second ejection means having an ejection port for ejecting a liquid onto the recording medium; The moving means is the recording medium, the discharge means, and the second discharge means are moved relatively in a predetermined direction; the discharge means and the second discharge means are arranged side by side in the predetermined direction, The air blowing means is disposed so that the air passes between the discharge means and the second discharge means. A recording device characterized by:

[0092] Item 7. Item 6. The recording device according to any one of items 1 to 6, a control unit that controls an adjustment operation for adjusting the concentration of solid components in the liquid based on the detection result of the detection unit; A recording device characterized by Item 8. Item 7. The recording device according to item 7, a circulation means for circulating the liquid between a liquid containing means for containing the liquid and the discharge means; A recording device characterized by:

[0093] Item 9. Item 8. The recording device according to item 8, the adjusting operation includes an operation of discharging the liquid from the discharge means. A recording device characterized by:

[0094] Item 10. Item 8. The recording device according to item 8, the adjusting operation includes an operation of discharging the liquid from the discharging means. A recording device characterized by:

[0095] Item 11. Item 8. The recording device according to item 8, the adjusting operation includes an operation of sucking the liquid from the discharge means. A recording device characterized by:

[0096] Item 12. The recording device according to any one of items 1 to 11, the ejection means is a full-line type ejection head; A recording device characterized by:

[0097] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0098] 1 recording device, 11 ejection head, 151a blower unit, 151b blower unit, 153 humidity sensor, OP ejection port

Claims

1. a moving means for relatively moving a recording medium and a discharging means having a discharge port for discharging a liquid onto the recording medium; a blowing means for blowing air to the discharge port; and a detection means for detecting the humidity of the air. A recording device characterized by:

2. a moving means for relatively moving a recording medium and a discharging means having a discharge port for discharging a liquid onto the recording medium; a blowing means for blowing air to the discharge port; a detection means for detecting humidity, The detection means is disposed on a path of the airflow generated by the blowing means. A recording device characterized by:

3. 3. The recording device according to claim 2, The detection means is disposed downstream of the blowing means in the direction of the airflow. A recording device characterized by:

4. 3. The recording device according to claim 2, The detection means is disposed upstream of the blowing means in the direction of the airflow. A recording device characterized by:

5. 2. The recording device according to claim 1, a flow velocity of the airflow blown by the blowing means is faster than a relative movement velocity between the recording medium and the ejection means; A recording device characterized by:

6. 2. The recording device according to claim 1, a second ejection means having an ejection port for ejecting a liquid onto the recording medium; The moving means is the recording medium, the discharge means, and the second discharge means are moved relatively in a predetermined direction; the discharge means and the second discharge means are arranged side by side in the predetermined direction, The air blowing means is disposed so that the air passes between the discharge means and the second discharge means. A recording device characterized by:

7. 2. The recording device according to claim 1, a control unit that controls an adjustment operation for adjusting the concentration of solid components in the liquid based on the detection result of the detection unit; A recording device characterized by:

8. 8. The recording device according to claim 7, a circulation means for circulating the liquid between a liquid containing means for containing the liquid and the discharge means; A recording device characterized by:

9. 9. The recording device according to claim 8, the adjusting operation includes an operation of discharging the liquid from the discharge means. A recording device characterized by:

10. 9. The recording device according to claim 8, the adjusting operation includes an operation of discharging the liquid from the discharging means. A recording device characterized by:

11. 9. The recording device according to claim 8, the adjusting operation includes an operation of sucking the liquid from the discharge means. A recording device characterized by:

12. 2. The recording device according to claim 1, the ejection means is a full-line type ejection head; A recording device characterized by:

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