Image formation device

Abstract

To reduce influence on an ink applied position when a recording head is cooled by using a fan in an image formation device.SOLUTION: An image formation device 100 includes: a platen 7 which holds a transported sheet 20 (a recording medium); a recording head 6 which discharges droplets to the sheet 20; a carriage 5 which is equipped with the recording head 6 and driven to scan and thereby perform printing; a fan 32 which cools the recording head 6 in the carriage 5; a head lifting mechanism 30 which may change a height direction position of the recording head 6 relative to the platen 7; and a control unit 34 which controls the rotation number of the fan 32. The control unit 34 changes the rotation number of the fan 32 according to the height direction position of the recording head 6 relative to the platen 7.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] An image forming apparatus such as an inkjet printer includes a recording head that ejects droplets of ink or the like onto a recording medium to form an image. In such an image forming apparatus, there is known a type in which the usable temperature range is set according to the ink characteristics, the specifications of the recording head, and the like, in order to eject droplets normally from the recording head.

[0003] Patent Document 1 discloses a configuration in which a blower fan is mounted on a carriage that carries and scans the print head, in order to suppress a rise in temperature of the print head and maintain the temperature within an appropriate range. Summary of the Invention [Problem to be solved by the invention]

[0004] Here, if the air current from the fan flows strongly toward the nozzle surface of the recording head, the droplets ejected from the recording head may be blown away by the air current and may deviate from the intended landing position.

[0005] An object of the present invention is to reduce the effect on the ink landing position when a fan is used to cool a print head in an image forming apparatus. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, an image forming apparatus according to one aspect of the present invention includes a platen that holds a recording medium being transported, a recording head that ejects droplets onto the recording medium, a carriage that carries the recording head and prints by scanning and driving it, a fan that cools the recording head within the carriage, a head lifting mechanism that can change the height position of the recording head relative to the platen, and a control unit that controls the rotation speed of the fan, and the control unit changes the rotation speed of the fan depending on the height position of the recording head relative to the platen. Effect of the Invention

[0007] When a fan is used to cool a print head in an image forming apparatus, the effect on the ink landing position can be reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an overall configuration of an image forming apparatus according to an embodiment; [Diagram 2] FIG. 2 is a perspective view showing a configuration of a main scanning mechanism of the carriage in FIG. 1; [Diagram 3] FIG. 1 is a schematic perspective view of a carriage according to an embodiment; [Figure 4] Schematic side view of a carriage [Diagram 5] Schematic diagram showing the sub-carriage in a raised state [Figure 6] Schematic diagram showing the operation of the fan in the carriage [Figure 7] Functional block diagram of a control unit related to print head cooling control [Figure 8] An example of the hardware configuration of the control unit [Figure 9] 1 is a flowchart of a first control of the print head cooling control according to the present embodiment. [Figure 10] FIG. 13 is a diagram showing an example of a first fan rotation speed control table; [Figure 11] 11 is a flowchart showing a second control of the print head cooling control according to the present embodiment. [Figure 12]FIG. 13 is a diagram showing an example of a second fan rotation speed control table; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0010] In the following description, the X, Y, and Z directions are perpendicular to each other. The X and Y directions are horizontal, and the Z direction is vertical. The X direction is the sub-scanning direction of the carriage 5 (the direction indicated by the arrow B in FIG. 1) and is the paper transport direction. The Y direction is the main scanning direction of the carriage 5 (the direction indicated by the arrow A in FIG. 1) and is the width direction of the paper. For ease of description, the positive Z direction may be referred to as the upper side and the negative Z direction may be referred to as the lower side in the following description.

[0011] Fig. 1 is a perspective view showing the overall configuration of an image forming apparatus 100 according to an embodiment. Fig. 2 is a perspective view showing the configuration of a main scanning mechanism 10 of a carriage 5 in Fig. 1.

[0012] As shown in Fig. 1, the image forming apparatus 100 according to this embodiment is a serial type inkjet recording apparatus. The image forming apparatus 100 includes an apparatus main body 1 and a support stand 2 that supports the apparatus main body 1. Inside the apparatus main body 1, a guide rod 3 and a guide stay 4, which are guide members, are hung between both side plates, and a carriage 5 is supported by the guide rod 3 and the guide stay 4 so as to be movable in the direction of arrow A (main scanning direction).

[0013] The carriage 5 is equipped with a recording head 6 consisting of a liquid ejection head that ejects ink droplets of each color: black (K), yellow (Y), magenta (M), and cyan (C). Each recording head 6 is equipped with a plurality of nozzles that eject droplets. Each recording head 6 also has an integrated head tank that supplies ink to the recording head 6.

[0014] The main scanning mechanism 10 that moves and scans the carriage 5 includes a drive motor 11 disposed on one side in the main scanning direction, a drive pulley 12 that is rotationally driven by the drive motor 11, a driven pulley 13 disposed on the other side in the main scanning direction, and a timing belt 14 that is a pulling member that is wound around between the drive pulley 12 and the driven pulley 13. Note that tension is applied to the driven pulley 13 outward (in the direction away from the drive pulley 12) by a tension spring.

[0015] In the recording area of ​​the main scanning area of ​​the carriage 5, the paper 20 is intermittently transported in the direction of arrow B (sub-scanning direction, paper transport direction) perpendicular to the main scanning direction of the carriage 5 by the suction transport unit.

[0016] A maintenance and recovery device 8 that maintains and recovers the recording head 6 is disposed in one end region of the main scanning region. Furthermore, outside the carriage movement region in the main scanning direction, or in the other end region of the main scanning region, a main cartridge 9 that contains ink of each color to be supplied to the subtank of the recording head 6 is detachably mounted in the device body 1. Furthermore, roll paper (hereinafter referred to as "paper 20") is set in the paper supply unit 21, but roll paper of a different width size can also be set.

[0017] In the image forming apparatus 100 configured as described above, image formation is performed as follows. First, the paper 20 conveyed from the paper feed unit 21 is conveyed by the conveying unit from the rear to the front of the device body 1 to the recording area. Next, the carriage 5 is moved in the main scanning direction, and while the suction conveying unit intermittently sends the paper 20 to the platen 7, the recording head 6 is driven in accordance with image information to eject droplets, thereby forming a desired image on the paper 20. Then, after the image has been formed, the paper 20 is cut to a predetermined length and discharged to a paper discharge tray arranged on the front side of the device body 1.

[0018] Although the configuration in which the paper 20 is cut and discharged has been described here, it is also possible to adopt a configuration in which the paper after image formation is wound up in the paper discharge section without being cut.

[0019] Next, the configuration of the carriage 5 will be described in detail.

[0020] Fig. 3 is a schematic perspective view of the carriage 5 according to the embodiment, and Fig. 4 is a schematic side view of the carriage 5.

[0021] As shown in FIGS. 3 and 4, a head holder 25 is held on the carriage 5 via a sub-carriage 18.

[0022] 3, the head holder 25 is equipped with recording heads 6a, 6b, and 6c arranged in a staggered pattern in the X direction (sub-scanning direction). When the recording heads are not to be distinguished from one another, they are referred to as "recording heads 6." The number of recording heads 6 mounted on the head holder 25 may be one, two, or more than three.

[0023] As shown in Fig. 3, the carriage 5 is provided with a reference shaft 15 as a reference member that extends in the same direction as the guide rod 3 (Y direction: main scanning direction). As shown in Figs. 3 and 4, a sub-carriage 18 is detachably and rotatably hung on the reference shaft 15 via an adjustment member 35. Also, as shown in Fig. 3, the sub-carriage 18 abuts against the carriage 5 in the rotation direction and is held (positioned).

[0024] 3 and 4, the adjustment member 35 is supported on the sub-carriage 18 so as to be rotatable around a sub-carriage rotation reference 37. That is, the adjustment member 35 is rotatable around the X direction (sub-scanning direction). The sub-carriage rotation reference 37 has a pin shape, and is configured to fix the adjustment member 35 by being inserted into the sub-carriage 18. Alternatively, it may be configured as a shoulder screw that is fastened to the sub-carriage 18.

[0025] 3, the sub-carriage 18 holds the head holder 25 by holding portions 18a, 18b along both ends of the head holder 25. Therefore, the sub-carriage 18 is detachably and rotatably hung on the reference shaft 15 via the adjustment member 35, and since the sub-carriage 18 holds the head holder 25, the head holder 25 is also held rotatably around the reference shaft 15.

[0026] By providing the reference axis 15 in the same direction (parallel) as the guide rod 3 of the carriage 5 in this way, the positional accuracy of the recording head 6 in the sub-scanning direction, height direction, tilt direction, and main scanning direction can be improved.

[0027] As shown in FIG. 4, below the carriage 5, a platen 7 is disposed for holding the transported paper 20.

[0028] By rotating the adjustment member 35 around the sub-carriage rotation reference 37, the sub-carriage 18 is supported at an angle with respect to the reference axis 15. Therefore, the parallelism between the recording head 6 and the platen 7 in the X direction (sub-scanning direction) can be adjusted.

[0029] As shown in Figs. 3 and 4, a cam member 38 is provided on the reference shaft 15. The cam member 38 has a peripheral surface that faces a direction perpendicular to the axial direction of the reference shaft 15. The shape of the peripheral surface as viewed in the Y direction is formed to have a major axis portion that is relatively far from the axis center of the reference shaft 15 and a minor axis portion that is relatively small, and is, for example, elliptical. The reference shaft 15 passes through the cam member 38, and the cam member 38 is fixed to the reference shaft 15 so as to surround the reference shaft 15 in the circumferential direction. This allows the cam member 38 to rotate integrally with the reference shaft 15.

[0030] 3 and 4, adjustment member 35 has a horizontal portion extending in the X direction and a vertical portion extending in the Z direction, and is formed so as to be L-shaped when viewed from the Y direction. Reference shaft 15 and cam member 38 are disposed below the horizontal portion of adjustment member 35, and the circumferential surface of cam member 38 is disposed so as to contact this horizontal portion from below. In other words, the circumferential surface of cam member 38 becomes a contact surface 39 with adjustment member 35.

[0031] The cam member 38 abuts against the adjustment member 35 at an abutment surface 39, and positions the sub-carriage 18 in the up-down direction. The rotation of the cam member 38 raises and lowers the sub-carriage 18, and the distance between the recording head 6 and the platen 7 can be changed. Therefore, the height of the recording head 6 can be adjusted according to the paper thickness, etc.

[0032] Here, the lifting and lowering operation of the sub-carriage 18 by the action of the cam member 38 will be described with reference to Figure 5 in addition to Figure 4. Figure 5 is a schematic diagram showing a state in which the sub-carriage 18 is lifted.

[0033] 4 shows a state in which the short diameter portion of the contact surface 39 of the cam member 38 is in contact with the adjustment member 35. At this time, the lower ends of the sub-carriage 18 and the head holder 25 are disposed at the same height as the lower end of the carriage 5. The distance between the recording head 6 and the platen 7 at this time is defined as D1.

[0034] On the other hand, FIG. 5 shows a state in which the reference shaft 15 has rotated approximately 90 degrees from the state in FIG. 4, and the long diameter portion of the abutment surface 39 of the cam member 38 is in contact with the adjustment member 35, as indicated by the arrow C. At this time, the horizontal portion of the adjustment member 35 is pressed upward by the abutment surface 39, and this pressing force causes the adjustment member 35, the sub-carriage 18 connected to the adjustment member 35, the head holder 25 connected to the sub-carriage 18, and the recording head 6 installed on the head holder 25 to rise together, as indicated by the arrow E. At this time, the height positions of the reference shaft 15, the carriage 5, and the platen 7 remain unchanged from those in FIG. 4. Therefore, the distance D2 between the recording head 6 and the platen 7 in the state in FIG. 5 becomes larger than the distance D1 in the state in FIG. 4, and the recording head 6 can be separated from the platen 7.

[0035] 4 and other examples show a configuration in which the cam member 38 and the reference shaft 15 are concentrically arranged, but the cam member 38 may be arranged so that the center of the elliptical shape is offset from the axis of the reference shaft 15. The cam member 38 may have any shape having at least the above-mentioned major axis and minor axis, and may have a shape other than an ellipse, such as an oval shape.

[0036] As a method for rotating the cam member 38, the cam member 38 can be fixed to the reference shaft 15 and rotated by rotating the reference shaft 15. The means for rotating the reference shaft 15 may be manual, or a drive source may be provided to automatically rotate the reference shaft 15 and raise and lower the recording head 6. This method makes it possible to operate the head raising and lowering of the carriage 5 from the outside.

[0037] By raising and lowering the head with the cam member 38, the distance between the recording head 6 and the platen 7 can be adjusted on the actual machine as desired to suit the printing medium, thereby expanding the range of print media that can be supported.

[0038] In this embodiment, the reference shaft 15, the cam member 38, and the adjustment member 35 function as a "head lifting mechanism 30" that can change the distance between the recording head 6 and the platen 7. Note that the head lifting mechanism 30 is not limited to a configuration that uses the cam member 38 or the like. For example, a configuration such as a ball screw and a guide rail may be applied.

[0039] As shown in FIG. 4 and FIG. 5, the platen 7 disposed below the carriage 5 has a built-in heater 31. The heater 31 functions as a temperature adjustment unit that adjusts the temperature of the platen 7 by heat generated by the apparatus itself. By adjusting the temperature of the platen 7 with the heater 31, it is possible to promote drying of droplets (ink) discharged from the recording head 6 to form an image on the paper 20 conveyed on the platen 7. In adjusting and controlling the temperature of the platen 7, a temperature detection sensor that detects the temperature of the platen 7 or the surroundings of the platen 7 may be provided. The temperature detection sensor may be disposed at any position as long as it can detect the temperature of the platen 7 or the surroundings of the platen 7. The temperature detection sensor may be provided not only to detect the temperature of the platen 7 or the surroundings, but also to detect the temperature of a specific part of the image forming apparatus, such as the recording head or its surroundings. By providing a temperature detection sensor, control based on the actual temperature of the apparatus becomes possible, and the accuracy of control is increased.

[0040] A carriage cover 33 may be provided on the carriage 5 to cover and house each element connected to the carriage 5. The carriage cover 33 is a box-shaped body that is disposed on the X-positive side of the carriage 5 in the perspective view of, for example, FIG. 3 and has an open bottom end surface 33A. As shown in FIGS. 4 and 5, an upper surface 33B of the box-shaped body of the carriage cover 33 is formed to be at the same height as the upper end of the carriage 5. The carriage cover 33 is formed to house at least the recording head 6, the adjustment member 35, and the cam member 38 inside.

[0041] Incidentally, the print head 6 of the carriage 5 tends to become unstable in ink ejection when the temperature becomes higher than a predetermined temperature that is generally determined in relation to the ink. Since the print head 6 is disposed close to and facing the platen 7, in the configuration in which the platen 7 is heated by controlling the heater 31 as in this embodiment, the print head 6 is easily affected by the rise in temperature of the platen 7. For this reason, in order to stabilize the ink ejection of the print head 6, it is necessary to cool the print head 6 against the heat from the platen 7.

[0042] 4 and 5, the carriage 5 is equipped with a fan 32. The fan 32 is installed, for example, on a side surface 33C of the carriage cover 33 on the X positive side, and blows air into the carriage cover 33.

[0043] 6 is a schematic diagram showing the operation of the fan 32 in the carriage 5. As shown by the arrow F in FIG. 6, when the fan 32 is operated, air F is blown into the carriage cover 33. Due to the influence of this blown air F, part of the air that was originally in the space inside the carriage cover 33 is pushed out of the carriage cover 33 through the gap. The air pushed out in this manner generates an airflow G on the side of the nozzle surface of the recording head 6, that is, the bottom end surface of the recording head 6 in FIG. 6. The airflow G that flows to the nozzle surface side cools the recording head 6, making it possible to suppress an increase in temperature of the recording head 6.

[0044] In such a mechanism for suppressing the rise in temperature of the recording head 6, if the air current G passing through the nozzle surface of the recording head 6 is strong, the ink dot droplets may be swept away while flying, causing the landing position accuracy to deteriorate, which may result in abnormal images. Therefore, although the air current G for cooling the recording head 6 is necessary, it must be suppressed to a level that does not affect the landing position accuracy.

[0045] Therefore, in this embodiment, print head cooling control is performed to adjust the rotation speed of the fan 32 to a degree that does not affect the landing position accuracy, depending on the height direction position of the print head 6 relative to the platen 7. This control is performed by a control unit 34 that controls the operation of the fan 32, reference shaft 15, heater 31, etc. The control unit 34 is installed at any location within the image forming apparatus 100, such as near the carriage 5 or the main scanning mechanism unit 10 of the carriage 5.

[0046] 7 is a functional block diagram of the control unit 34 related to print head cooling control. The control unit 34 has a head height control unit 341, a platen heater control unit 342, a fan rotation speed control unit 343, and fan rotation speed control tables 344 and 345 as functions related to fan rotation speed control.

[0047] The head height control unit 341 rotates the reference shaft 15 to adjust the position of a contact surface 39 of a cam member 38 fixed to the reference shaft 15, thereby controlling the height position of the recording head 6 with respect to the platen 7. The head height control unit 341 is electrically connected to, for example, a control system of a drive source of the reference shaft 15. The head height control unit 341 can output a control command according to a desired height position to the drive source of the reference shaft 15, and ultimately control the height position of the recording head 6.

[0048] The platen heater control unit 342 adjusts the heat generation temperature of the heater 31 to control the temperature of the platen 7. The platen heater control unit 342 is electrically connected to a control system of the heater 31. The platen heater control unit 342 outputs a control command to the heater 31 according to a desired set temperature of the platen 7, and can ultimately control the temperature of the platen 7.

[0049] The fan rotation speed control unit 343 controls the rotation speed of the fan 32. The fan rotation speed control unit 343 is electrically connected to a control system of a drive source of the fan 32. The fan rotation speed control unit 343 outputs a control command corresponding to a desired rotation speed to the fan 32 to control the rotation speed of the fan 32.

[0050] The fan rotation speed control tables 344 and 345 record input information including at least one of information on the height position of the print head 6 and information on the set temperature of the platen 7 in association with the fan rotation speed as output information. The fan rotation speed control unit 343 determines a control command for the fan rotation speed by referring to the fan rotation speed control tables 344 and 345. In this embodiment, as described later, two types of tables 344 and 345 are created, and the fan rotation speed control unit 343 selects the table to be used depending on the desired control.

[0051] The image forming apparatus 100 of this embodiment also includes a head height detection unit 36 ​​(detection unit). The head height detection unit 36 ​​detects the height position of the recording head 6 with respect to the platen 7. The height position is information such as the distance D1 shown in Fig. 4 or the distance D2 shown in Fig. 5. As a specific configuration of the head height detection unit 36, any configuration can be applied, such as a configuration in which the rotational position of the cam member 38 is recognized and determined by a sensor, or a configuration in which an optical length measuring sensor is disposed in the head holder 25.

[0052] The head height detection unit 36 ​​is electrically connected to the control unit 34, and outputs information about the detected height position to the fan rotation speed control unit 343. The fan rotation speed control unit 343 sets a rotation speed command for the fan 32 based on the height information input from the head height detection unit 36. Information about the set temperature of the platen 7 is also input to the fan rotation speed control unit 343 from the platen heater control unit 342. The fan rotation speed control unit 343 sets the rotation speed command for the fan 32 based on the set temperature information input from the platen heater control unit 342.

[0053] Fig. 8 is an example of a hardware configuration diagram of the control unit 34. As shown in Fig. 4, the control unit 34 can be physically configured as a computer device or a circuit board including a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102 and a ROM (Read Only Memory) 103 which are main storage devices, an input device 104 such as a keyboard and a mouse which are input devices, an output device 105 such as a display, a communication module 106 which is a data transmission / reception device such as a network card, an auxiliary storage device 107, and the like.

[0054] 7 are realized by loading predetermined computer software onto hardware such as the CPU 101, RAM 102, etc., to operate the communication module 106, the input device 104, the output device 105, etc. under the control of the CPU 101, and by reading and writing data from and to the RAM 102 and the auxiliary storage device 107. Among the functions of the control unit 34, the fan rotation speed control tables 344 and 345 can be realized by utilizing a part of the storage device such as the RAM 102 of the control unit 34 and the auxiliary storage device 107.

[0055] Image forming apparatus 100 of this embodiment includes a platen 7 that holds paper 20 (recording medium) to be conveyed, a recording head 6 that ejects droplets onto paper 20, a carriage 5 that carries the recording head 6 and performs printing by scanning and driving it, a fan 32 that cools the recording head 6 inside the carriage 5, a head lifting mechanism 30 that can change the height position of the recording head 6 relative to the platen 7, and a control unit 34 that controls the rotation speed of the fan 32. The control unit 34 changes the rotation speed of the fan 32 depending on the height position of the recording head 6 relative to the platen 7.

[0056] For example, in Patent Document 1 and other documents, there is a conventional technique in which a blower fan 32 is mounted on a carriage 5 that carries and scans a recording head 6 in order to suppress a temperature rise of the recording head 6 and maintain an appropriate temperature range. In these conventional techniques, when the airflow G from the fan 32 flows strongly toward the nozzle surface side of the recording head 6, the droplets ejected from the recording head 6 may be blown away by the airflow G and may deviate from the intended landing position. This problem tends to become more pronounced as the distance between the platen 7 that holds the paper 20 being transported and the recording head 6 disposed above the platen 7 becomes relatively large. On the other hand, when the distance between the recording head 6 and the platen 7 is large, the effect of heat generated by the heater 31 disposed on the platen 7 on the recording head 6 becomes smaller, and the temperature rise of the recording head 6 tends to become smaller.

[0057] Therefore, in this embodiment, as configured above, the head lifting mechanism 30 can change the height direction position of the recording head 6 relative to the platen 7, and the control unit 34 changes the rotation speed of the fan 32 according to the height direction position of the recording head 6 relative to the platen 7. With this configuration, the rotation speed of the fan 32 is controlled so that the airflow G is relatively weakened, particularly as the distance between the platen 7 and the recording head 6 increases, thereby making it possible to reduce the effect on the ink landing position when the recording head 6 is cooled using the fan 32 in the image forming apparatus 100. Furthermore, with this control, the cooling effect of the recording head 6 can be maintained even if the airflow G of the fan 32 is weakened when the distance between the platen 7 and the recording head 6 is assumed to be large.

[0058] Next, the procedure of print head cooling control will be described with reference to Figs. 9 to 12. The print head cooling control is outlined as follows. When the height position of the print head 6 relative to the platen 7 is relatively high, the temperature rise of the print head 6 caused by the platen heater 31 is smaller than usual. Therefore, even if the airflow G of the fan 32 is small (weak), the print head temperature can be maintained at a predetermined level. In addition, there is room for further adjustment of the airflow G of the fan 32 depending on the set temperature of the platen 7. For example, when the set temperature of the platen 7 is relatively low and the height position of the print head 6 is relatively high, the airflow G of the fan 32 can at least keep the temperature rise of the print head 6 within the specification range.

[0059] In this embodiment, control is performed to adjust the rotation speed of the fan 32 in consideration of at least one of the height position of the print head 6 and the set temperature of the platen 7, so as to reduce the effect on the ink landing position and to cool the print head 6. Specifically, a first control shown in Figs. 9 and 10 and a second control shown in Figs. 11 and 12 can be performed.

[0060] 9 is a flowchart of the first control of the print head cooling control of this embodiment. In the first control, the rotation speed of the fan 32 is made variable depending on the height position of the print head 6. In the first control, the fan rotation speed control unit 343 controls the rotation speed using a first fan rotation speed control table 344.

[0061] In step S101, an instruction to rotate the fan 32 is received. This instruction may be generated by the control unit 34 in response to the operation of the image forming apparatus 100, or may be received by the control unit 34 from another control device within the image forming apparatus 100.

[0062] In step S102, the head height detection unit 36 ​​checks the distance information (information on the height direction position) between the recording head 6 and the platen 7. The head height detection unit 36 ​​outputs the detected information on the height direction position to the fan rotation speed control unit 343 of the control unit 34.

[0063] In step S103, the fan rotation speed control unit 343 determines whether or not a fan rotation speed variable condition is met. Examples of the fan rotation speed variable condition include when the height direction position of the print head 6 acquired in step S102 is equal to or greater than a predetermined threshold value, when the set temperature of the platen 7 is equal to or less than a predetermined threshold value, etc. Information on the set temperature of the platen is provided to the fan rotation speed control unit 343 from the platen heater control unit 242.

[0064] If it is determined in step S103 that the fan rotation speed variable condition is met (YES in S103), the process proceeds to step S104, where the fan rotation speed control unit 343 determines the rotation speed of the fan 32 using the first fan rotation speed control table 344.

[0065] Fig. 10 is a diagram showing an example of the first fan rotation speed control table 344. As shown in Fig. 10, in the first fan rotation speed control table 344, information on the height direction position of the recording head (head height) and information on the change amount of the rotation speed of the fan 32 (fan rotation speed) are linked and recorded as one information set.

[0066] In the example of FIG. 10, four different head height types are set with "default" as the standard. "+1" means that the head height is a specified range above the standard height position set by default. "+2" means that the head height is a specified range above the upper limit height position of "+1". "+3" means that the head height is a specified range above the upper limit height position of "+2".

[0067] In the example of FIG. 10, the fan rotation speed is also set in four stages based on "default", which is the reference rotation speed of the fan 32. When the head height is "default", the fan rotation speed is also set to "default". When the head height is "+1", the fan rotation speed is set to "-5%", that is, a rotation speed that is 5% lower than the reference rotation speed. When the head height is "+2", the fan rotation speed is set to "-10%", that is, a rotation speed that is 10% lower than the reference rotation speed. When the head height is "+3", the fan rotation speed is set to "-15%", that is, a rotation speed that is 15% lower than the reference rotation speed.

[0068] The fan rotation speed control unit 343 obtains a command value for the fan rotation speed from a first fan rotation speed control table 344 illustrated in FIG. 10, using the information on the current height direction position of the print head 6 obtained in step S102.

[0069] On the other hand, if it is determined in step S103 that the fan rotation speed variable condition is not met (NO in S103), the process proceeds to step S105, where the fan rotation speed is set to the normal fan rotation speed by the fan rotation speed control unit 343. The normal fan rotation speed is, for example, the same value as "default" in FIG.

[0070] In step S106, the fan rotation speed control unit 343 controls the rotation of the fan 32 based on the command value for the fan rotation speed set in step S104 or S105. When the process of step S106 is completed, this control flow ends.

[0071] In the first control, the head height (height position of the recording head 6) can be changed stepwise by the head lifting mechanism 30. In addition, the fan rotation speed control unit 343 of the control unit 34 changes the rotation speed of the fan 32 stepwise according to the height direction position of the recording head 6. For example, by using a first fan rotation speed control table 344 shown in FIG. 10, the rotation speed of the fan 32 can be reduced stepwise as the head height increases. This makes it possible to more reliably reduce the deviation of the landing position of the ink dots ejected from the recording head 6 due to the influence of the airflow G of the fan 32 when the height position of the recording head 6 becomes higher relative to the platen 7.

[0072] 11 is a flowchart of the second control of the print head cooling control of this embodiment. In the second control, the rotation speed of the fan 32 is varied according to the height position of the print head 6 and the set temperature of the platen 7. In the second control, the fan rotation speed control unit 343 controls the rotation speed using a second fan rotation speed control table 345.

[0073] In step S201, an instruction to rotate the fan 32 is received. This instruction may be generated by the control unit 34 in response to the operation of the image forming apparatus 100, or may be received by the control unit 34 from another control device within the image forming apparatus 100.

[0074] In step S202, the head height detection unit 36 ​​checks the distance information (information on the height direction position) between the recording head 6 and the platen 7. The head height detection unit 36 ​​outputs the detected information on the height direction position to the fan rotation speed control unit 343 of the control unit 34.

[0075] In step S203, the set temperature of the platen 7 is confirmed by the fan rotation speed control unit 343. The fan rotation speed control unit 343 obtains information on the set temperature from the platen heater control unit 342, for example.

[0076] In step S204, it is determined whether or not a fan rotation speed variable condition is met by the fan rotation speed control unit 343. Examples of the fan rotation speed variable condition include a case where the height direction position of the print head 6 acquired in step S202 is equal to or greater than a predetermined threshold, a case where the set temperature of the platen 7 acquired in step S203 is equal to or less than a predetermined threshold, etc.

[0077] If it is determined in step S204 that the fan rotation speed variable condition is met (YES in S204), the process proceeds to step S205, where the fan rotation speed control unit 343 determines the rotation speed of the fan 32 using the second fan rotation speed control table 345.

[0078] Fig. 12 is a diagram showing an example of the second fan rotation speed control table 345. As shown in Fig. 12, in the second fan rotation speed control table 345, information on the height direction position of the print head (head height), information on the set temperature (heater temperature) of the platen 7, and information on the change amount of the rotation speed of the fan 32 (fan rotation speed) are linked and recorded as a set of information. Note that in the example of Fig. 12, as in Fig. 10, four stages are set as the type of head height, with "default" as the standard. The contents of each stage are the same as in Fig. 10.

[0079] 12, three heater temperature levels are set for each head height level: "20-40°C", "40-60°C", and "60-80°C". Furthermore, the fan speed is also set for each heater temperature level. In other words, a total of 12 fan speed levels are set by multiplying the four head height levels by the three heater temperature levels.

[0080] In the example of FIG. 12, when the head height is set to "default", the fan rotation speeds are all set to "default" regardless of the heater temperature.

[0081] When the head height is "+1", the fan speed is set to "-5%" when the heater temperature is "20~40°C", and the fan speed is set to "default" when the heater temperature is "40~60°C" or "60~80°C".

[0082] When the head height is "+2", the fan speed is set to "-5%" when the heater temperature is "20~40°C" or "40~60°C", and the fan speed is set to "default" when the heater temperature is "60~80°C".

[0083] When the head height is "+3", the fan speed is set to "-10%" when the heater temperature is "20~40°C", the fan speed is set to "-5%" when the heater temperature is "40~60°C", and the fan speed is set to "default" when the heater temperature is "60~80°C".

[0084] The fan rotation speed control unit 343 obtains a command value for the fan rotation speed from a second fan rotation speed control table 345 illustrated in FIG. 12, using information on the current height direction position of the print head 6 obtained in step S202 and information on the current set temperature of the platen 7 obtained in step S203.

[0085] On the other hand, if it is determined in step S204 that the fan rotation speed variable condition is not met (NO in S204), the process proceeds to step S206, where the fan rotation speed is set to the normal fan rotation speed by the fan rotation speed control unit 343. The normal fan rotation speed is, for example, the same value as "default" in FIG.

[0086] In step S207, the fan rotation speed control unit 343 controls the rotation of the fan 32 based on the command value for the fan rotation speed set in step S205 or S206. When the process of step S207 is completed, this control flow ends.

[0087] In the second control, the fan rotation speed control unit 343 of the control unit 34 changes the rotation speed of the fan 32 according to the temperature set by the heater 31 of the platen 7 and the height position of the recording head 6. For example, by using a second fan rotation speed control table 345 shown in FIG. 12, the fan rotation speed can be lowered according to the heater set temperature in addition to the height position of the recording head 6, and the influence of the landing position deviation due to the head height increase can be further reduced. This makes it possible to more reliably reduce the landing position deviation of ink dots due to the influence of the air flow G of the fan 32 caused by the height position of the recording head 6 being higher while suppressing the temperature rise of the recording head 6 due to the heating of the platen 7. In addition, since two types of information, the temperature set by the heater 31 of the platen 7 and the height position of the recording head 6, are taken into consideration, it becomes possible to more finely control the rotation speed of the fan 32 so as to achieve a good balance between the cooling effect of the recording head 6 and the effect of reducing the influence on the ink landing position.

[0088] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs.

[0089] In the above embodiment, a configuration in which the heater 31 is built into the platen 7 has been exemplified, but any element that can function as a temperature adjustment unit that adjusts the temperature of the platen 7 may be used other than the heater 31. The heater 31 may also be installed outside the platen 7 and configured to transfer heat generated by its own device to the platen. [Explanation of symbols]

[0090] 100 Image forming device 5 Carriage 6 Recording head 7 Platen 20 Paper (recording media) 30 Head lift mechanism 31 Heater (temperature control unit) 32 Fans 34 Control section 36 Head height detector (detector) [Prior art documents] [Patent documents]

[0091] [Patent Document 1] JP 2005-254619 A

Claims

1. a platen for holding the recording medium to be conveyed; a recording head for ejecting droplets onto the recording medium; a carriage that carries the recording head and that performs printing by scanning and driving the carriage; a fan for cooling the recording head in the carriage; a head lifting mechanism capable of changing a height direction position of the recording head with respect to the platen; A control unit for controlling the rotation speed of the fan; Equipped with the control unit changes the rotation speed of the fan in accordance with a height direction position of the recording head relative to the platen. Image forming device.

2. a detection unit that detects the height direction position of the recording head, the head lifting mechanism is capable of changing the height direction position of the recording head with respect to the platen in a stepwise manner, The control unit changes the rotation speed of the fan in a stepwise manner in accordance with the height direction position detected by the detection unit. The image forming apparatus according to claim 1 .

3. a temperature adjusting unit for adjusting a temperature of the platen, the control unit changes the rotation speed of the fan in response to a temperature set by the temperature adjustment unit of the platen and the height direction position.

3. The image forming apparatus according to claim 1 or 2.

Images