Image forming apparatus

Abstract

To provide an image forming apparatus capable of suppressing a situation in which a pressing mark is formed on a medium.SOLUTION: An image forming apparatus 1 according to the present disclosure includes a transport mechanism 10 that transports a medium by a transport belt 11 in a state in which the medium is bonded to an adhesive, a pressing mechanism 30 that includes a pressing roller 31 that presses the medium against the transport belt 11, an image forming unit 20 that performs image formation on the medium, and a controller 40 that controls the transport mechanism 10 and the image forming unit 20 and operates the pressing mechanism 30 in conjunction with switching between a transport operation and an image forming operation. During the image forming operation, the pressing mechanism 30 is operated so that the pressing force applied to the medium becomes zero or smaller than the pressing force by the own weight of the pressing roller 31 while maintaining the state in which the pressing roller 31 is close to the medium.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Conventionally, inkjet textile printers (hereinafter referred to as image forming apparatuses) that perform inkjet printing on long sheet-shaped fabrics have been known.

[0003] In this type of image forming apparatus, a sticky resin called an adhesive (hereinafter referred to as adhesive) is applied to the conveyor belt, and a process is performed before printing to adhere the media (here, fabric) to the adhesive by pressing it with a pressure roller. In this type of image forming apparatus, the media is conveyed while fixed on the conveyor belt, and inkjet printing is performed. This is because, since the media is fabric, it is prone to expansion / contraction and positional misalignment during printing. In other words, in this type of image forming apparatus, fixing the media on the conveyor belt prevents degradation of the image quality of the image formed on the media. See, for example, Patent Document 1.

[0004] Furthermore, when the pressure roller presses the media, if the pressure of the pressure roller is too strong, the fibers on the surface of the fabric may curl or bend, resulting in a deterioration in the condition of the fabric surface. On the other hand, if the pressure of the pressure roller is too weak, the fabric may wrinkle and / or lift, resulting in an inability to properly fix the fabric and to record a pattern of suitable quality. Therefore, in this type of image forming device, the pressure applied to the media is generally adjusted to an appropriate value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-83040 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, this type of image forming apparatus often employs a method called a scan type, in which printing is performed while the head unit is scanned in a direction perpendicular to the transport direction of the medium.

[0007] However, in a scan-type image forming device, the media must be stopped while the head unit scans and prints, so printing is performed by repeating the process of media transport → transport stop → head unit scan (print). If pressure from the pressure roller continues to be applied to the same part of the media while transport is stopped, the surface condition of only that part may change, and after printing, a printing defect called a pressure mark may occur, where the color is different from other parts.

[0008] FIG. 1 shows an example of an indentation mark formed on a medium (here, fabric). FIG. 1A is a photograph of the fabric taken from above. FIG. 1B is an enlarged photograph of the area surrounded by a white frame in FIG. 1A. FIG. 1C is a further enlarged photograph of FIG. 1B. FIG. 1D is a side cross-sectional view of FIG. 1C. In FIG. 1, an indentation mark has been formed in area T1 of the fabric.

[0009] As described above, this type of image forming apparatus uses a pressure roller to apply pressure to the media (here, fabric) to adhere it to the adhesive on the conveyor belt. However, if pressure is applied to one part of the media for a longer period of time than other parts, the state of adhesion to the adhesive will differ from that of other parts. If the state of adhesion of the fabric to the adhesive differs, the ink will soak into that part differently from the other parts. As a result, an area will appear on a straight line along the pressure roller where the color after printing will differ from that of the other parts. This is called a pressure mark.

[0010] The present invention has been made in view of the above-mentioned problems, and has an object to provide an image forming apparatus that can prevent pressure marks from being formed on the medium. [Means for solving the problem]

[0011] The main invention that solves the above-mentioned problems is: a conveyance mechanism having a conveyance belt and an adhesive disposed on the conveyance belt, the conveyance mechanism conveying the medium on the conveyance belt while the medium is adhered to the adhesive; a pressure mechanism including a pressure roller disposed opposite the conveyor belt and pressing the medium against the conveyor belt, and a pressure receiving member disposed on the opposite side of the conveyor belt from the pressure roller; an image forming unit that forms an image on the medium; a control unit that controls the conveying mechanism and the image forming unit so that a conveying operation and an image forming operation are alternately and repeatedly performed, and that operates the pressing mechanism in conjunction with switching between the conveying operation and the image forming operation; Equipped with The control unit During the transport operation, the pressing mechanism is operated so that a pressing force due to the weight of the pressing roller is applied to the medium; During the image forming operation, the pressure mechanism is operated so that the pressure roller is kept close to the medium and the pressure applied to the medium is zero or smaller than the pressure caused by the weight of the pressure roller. An image forming apparatus. [Effects of the Invention]

[0012] According to the image forming apparatus of the present invention, it is possible to prevent pressure marks from being left on the medium. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a diagram showing an example of an indentation formed on a medium; [Figure 2] FIG. 1 is a diagram showing an example of the overall configuration of an image forming apparatus according to a first embodiment. [Figure 3](First embodiment) An enlarged view showing a state in which a pressure roller of an image forming apparatus presses a medium. [Figure 4] (First embodiment) An example of the configuration of an image forming unit of an image forming apparatus [Figure 5] (First embodiment) A diagram showing an example of the configuration of a control system of an image forming apparatus. [Figure 6] (First embodiment) A diagram showing the states of the pressing mechanism during each operation of the image forming apparatus (standby, conveying operation, and image forming operation). [Figure 7] (First embodiment) A diagram showing an example of the configuration of a support structure for a pressing mechanism. [Figure 8] (First embodiment) A diagram showing an example of the operation of the pressing mechanism. [Figure 9] (First embodiment) A time chart showing an example of the operation of each unit controlled under the control of the control unit. [Figure 10] (First embodiment) A time chart showing an example of the operation of each unit controlled under the control of the control unit. [Figure 11] (Second embodiment) A diagram showing the states of the pressing mechanism during each operation of the image forming apparatus (standby, conveying operation, and image forming operation). [Figure 12] (Second embodiment) A diagram showing an example of the configuration of a support structure for a pressing mechanism. [Figure 13] (Second embodiment) A diagram showing an example of the operation of the pressing mechanism. [Figure 14] (Third embodiment) A diagram showing an example of the configuration of a support structure for a pressing mechanism. [Figure 15] (Fourth embodiment) A diagram showing an example of the configuration of a support structure for a pressing mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0015] (First embodiment) <Overall configuration of image forming apparatus> Hereinafter, with reference to FIGS. 2 to 5, first, a schematic configuration of an inkjet image forming apparatus 1 (hereinafter abbreviated as "image forming apparatus 1") according to one embodiment of the present invention will be described.

[0016] Fig. 2 is a diagram showing an example of the overall configuration of the image forming apparatus 1. Fig. 3 is an enlarged view showing a state in which the pressure roller 31 of the image forming apparatus 1 presses the medium P. Fig. 4 is a diagram showing an example of the configuration of the image forming unit 20 of the image forming apparatus 1. Fig. 5 is a diagram showing an example of the configuration of the control system of the image forming apparatus 1.

[0017] The image forming apparatus 1 includes a conveying mechanism 10, an image forming section 20, a pressing mechanism 30, and a control section 40.

[0018] Any long sheet-like fabric can be used as the fabric serving as the media P. Examples of fabric include cotton, linen, silk, leather, and urethane fiber.

[0019] The conveying mechanism 10 includes a conveying belt 11 , a guide roller 12 , a feeder 13 , a peeling roller 14 , and a winder 15 .

[0020] The transport mechanism 10 transports the medium P sent out from the send-out machine 13 on the transport belt 11, and then transports it towards the winder 15. The send-out machine 13 rotatably supports a reel around which the medium P is wound in a roll, and sends the medium P out to the transport path. The winder 15 rotatably supports a reel that winds up the medium P, and winds up the medium P from the transport path after printing has been completed.

[0021] The conveyor belt 11 constitutes a conveying path that conveys the medium P sent out from the feeder 13 to the winder 15 via the image forming area of ​​the image forming unit 20. The conveyor belt 11 conveys the medium P along a predetermined conveying direction. The conveyor belt 11 is an endless belt that is looped and is stretched over a first conveyor roller 11b and a second conveyor roller 11c.

[0022] An adhesive 11a is applied to the conveying surface, which is the surface of the conveyor belt 11. Therefore, while the media P is being conveyed by the conveyor belt 11, it is fixed to the adhesive 11a formed on the conveying surface of the conveyor belt 11. Here, the adhesive 11a used is an adhesive organic solvent (i.e., adhesive) applied to a uniform thickness on the conveyor belt 11. However, adhesive tape may also be used as the adhesive 11a.

[0023] The guide roller 12 is disposed in the transport path between the feeder 13 and the pressure roller 31, and guides the transport path of the media P so that the media P fed from the feeder 13 wraps around the pressure roller 31. That is, the transport mechanism 10 according to this embodiment uses the guide roller 12 to guide the media P fed from the feeder 13 so that it wraps around the pressure roller 31, and places the media P on the transport belt 11 with an appropriate tension applied to the media P.

[0024] The peeling roller 14 is disposed in the transport path between the conveyor belt 11 and the winder 15, and peels the adhesive 11a from the medium P sent from the conveyor belt 11 to the winder 15. The peeling roller 14 rotates in response to the rotation of the conveyor belt 11. The outer peripheral surface of the peeling roller 14 is in a state in which a predetermined friction force is generated between the medium P and the peeling roller 14. When the peeling roller 14 rotates, the medium P transported by the conveyor belt 11 is pulled toward the peeling roller 14. As a result, the adhesive 11a is peeled off the medium P at a predetermined position after the medium P has passed through the image forming unit 20.

[0025] In this way, the medium P sent out from the feeder 13 is wound around the pressure roller 31 and then transported onto the conveyor belt 11. Then, as the medium P is transported on the conveyor belt 11, it passes through the pressure roller 31 of the pressure mechanism 30 and the image forming unit 20. Then, after passing through the image forming unit 20, the medium P is peeled off from the adhesive 11a of the conveyor belt 11 by the peeling roller 14, and then taken up by the winder 15.

[0026] The pressing mechanism 30 fixes the medium P to the adhesive 11a on the conveyor belt 11. The pressing mechanism 30 has a pressing roller 31, a pressure receiving member 32, and a support structure 33 (see FIG. 7) that supports the pressing roller 31 and the pressure receiving member 32.

[0027] The pressure roller 31 is disposed upstream of the conveyor belt 11 in the conveying direction (i.e., upstream of the image forming unit 20) and faces the conveying surface of the conveyor belt 11, and presses the media P against the conveyor belt 11. The pressure roller 31 has a weight of, for example, several hundred kg, and applies a pressing force to the media P due to its own weight. That is, the pressure roller 31 presses the media P against the conveying surface of the conveyor belt 11, thereby adhering the media P to the adhesive 11a. The pressure roller 31 is supported by a support structure 33 in a freely rotatable state on both sides of the conveyor belt 11 in the width direction (referring to the direction perpendicular to the conveying direction; the same applies hereinafter). That is, the pressure roller 31 is disposed so as to be able to press the media P against the conveyor belt 11 across the entire width in the width direction.

[0028] The pressure roller 31 has a built-in heater 31a and is configured to be able to heat the medium P by the heat generated by the heater 31a when applying pressure to the medium P. This makes it possible to smooth out wrinkles formed in the medium P. Furthermore, by heating the medium P, it is possible to improve the adhesion of the medium P to the adhesive 11a.

[0029] The pressure receiving member 32 is disposed on the back side of the conveyor belt 11, facing the pressure roller 31 across the conveyor belt 11. The pressure receiving member 32 receives the pressure applied to the media P by the pressure roller 31. That is, by sandwiching the media P between the pressure roller 31 and the pressure receiving member 32, the pressure of the pressure roller 31 due to its own weight is applied to the media P.

[0030] The pressure receiving member 32 is configured, for example, by a backup roller that rotates following the rotation of the conveyor belt 11. The pressure receiving member 32 is supported by a support structure 33 in a freely rotatable state on both sides of the width direction of the conveyor belt 11. However, the pressure receiving member 32 may be configured by a plate-shaped backup plate instead of a backup roller.

[0031] The conveyor belt 11 and the medium P pass between the pressure roller 31 and the pressure receiving member 32. As the medium P passes through, it is pressed against the conveyance surface by the pressure roller 31. As a result, the medium P is fixed to the adhesive 11a.

[0032] The support structure 33 supports the pressure roller 31 and the pressure receiving member 32. The support structure 33 is configured to be able to move the support position of the pressure roller 31 or the pressure receiving member 32 (in this embodiment, the support position of the pressure roller 31) up and down. The support structure 33 is configured to be able to change the support position of the pressure roller 31 so that the pressure is lower than the pressure caused by the weight of the pressure roller 31 during image formation operation of the image forming apparatus 1 (details will be described later).

[0033] The image forming unit 20 forms a predetermined image by ejecting ink onto the medium P, which is fixed with the adhesive 11a and transported by the transport belt 11. The image forming unit 20 has a head unit 21 and a head support unit 22 (see FIG. 4).

[0034] The head unit 21 has recording heads corresponding to the colors of black, cyan, magenta, and yellow, for example. Each recording head for a color has nozzles that eject the corresponding ink formed to face the transport surface. The head unit 21 according to this embodiment uses a piezo method for ejecting ink. The piezo method is a method in which pressure according to image data is applied to ink stored in a pressure chamber by an actuator that uses a piezoelectric element, and the ink is ejected from nozzles that communicate with the pressure chamber to form an image.

[0035] The head support section 22 supports the head unit 21 in a manner that allows the head unit 21 to move back and forth in a direction (hereinafter referred to as the scanning direction) perpendicular to the transport direction (Y direction in FIG. 4). The head support section 22 is attached, for example, to the housing 10a of the transport mechanism 10, and supports the head unit 21 in a state that allows it to slide against the housing 10a. The head support section 22 is configured to include guide rails that allow the head unit 21 to move back and forth along the scanning direction. That is, the image forming apparatus 1 according to this embodiment performs printing on the medium P using a scan printing method.

[0036] The control unit 40 has a CPU 41, RAM 42, ROM 43, storage unit 44, etc., and controls the overall operation of the image forming apparatus 1. That is, the CPU 41 reads a program corresponding to the processing content from the ROM 43, loads it into the RAM 42, and works with the loaded program to centrally control the operation of each block of the image forming apparatus 1. At this time, various data stored in the storage unit 44 is referenced. The storage unit 44 is configured, for example, with a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0037] The head driving section 50 is configured to include a driving motor that moves the head unit 21 back and forth along the head support section 22 (guide rail), and causes the head unit 21 to perform a scanning operation under the control of the control section 40. Then, under the control of the control section 40, the head driving section 50 supplies driving signals corresponding to image data to the recording elements of the head unit 21 at appropriate timing, thereby causing the nozzles of the head unit 21 to eject ink in an amount corresponding to the pixel values ​​of the image data.

[0038] The conveyance drive unit 60, under the control of the control unit 40, controls the operation of the conveyor belt 11, the feeder 13, the peeling roller 14, and the winder 15 of the conveyance mechanism 10. The conveyance drive unit 60 operates the conveyor belt 11 at a predetermined speed and timing, for example, by driving the motor of the conveyor roller 11b across which the conveyor belt 11 is stretched. The conveyance drive unit 60 also supplies drive signals to the motors that operate the feeder 13 and the winder 15, thereby controlling the operation of feeding out the media P from the feeder 13 and the operation of winding up the media P in the winder 15.

[0039] The image processing unit 70 performs predetermined image processing on the image data input from the input / output interface 80, and stores the obtained image data in the storage unit 44. This image processing includes correction processing for correcting the image data, as well as color conversion processing, gradation correction processing, pseudo-halftoning processing, and the like.

[0040] The input / output interface 80 is connected to an input / output interface of an external device (for example, a personal computer) and mediates the transmission and reception of data between the control unit 40 and the external device. The input / output interface 80 is configured, for example, by any one of various serial interfaces, various parallel interfaces, or a combination of these.

[0041] With the above configuration, the control unit 40 executes the printing operation, for example, as follows.

[0042] The control unit 40 first causes the transport mechanism 10 to transport the medium P in the transport direction (X direction in FIG. 4) by a width that allows image formation by the head unit 21, and then stops the transport. Then, with transport by the transport mechanism 10 stopped, the control unit 40 ejects ink according to the pattern of image data onto the medium P while scanning (Y direction in FIG. 4) the head unit 21. Then, after printing for one scan is completed, the control unit 40 again transports the medium P in the transport direction by the width of one scan.

[0043] In this way, the image forming apparatus 1 of this embodiment alternates between a transport operation for transporting the media P and an image forming operation for forming an image on the media P while the transport operation is stopped, thereby printing an image of the desired size on the media P.

[0044] <Detailed configuration of the pressing mechanism 30> The pressure mechanism 30 is configured so that the support position of the pressure roller 31 or the pressure receiving member 32 (in this embodiment, the pressure roller 31) is different when the image forming device 1 is in standby mode, during transport operation, and during image forming operation.

[0045] 6A, 6B, and 6C are diagrams showing the states of the pressing mechanism 30 during each operation (standby, transport operation, and image forming operation) of the image forming apparatus 1. FIGS. 6A, 6B, and 6C respectively show the states of the pressing mechanism 30 during the following operations. FIG. 6A: Image forming apparatus 1 is on standby (neither the conveying operation nor the image forming operation is being performed) FIG. 6B: During the conveying operation of the image forming apparatus 1 FIG. 6C: Image forming apparatus 1 during image forming operation

[0046] As described above, in the image forming apparatus 1 according to this embodiment, the pressure roller 31 presses the medium P against the conveyor belt 11, thereby adhering the medium P to the adhesive 11a on the conveyor belt 11. Then, by forming an image on the medium P while the medium P is fixed to the adhesive 11a on the conveyor belt 11, expansion / contraction and positional deviation of the medium P are suppressed. However, if the pressure of the pressure roller 31 due to its own weight continues to be applied to the same location, pressure marks will be generated on the medium P.

[0047] Therefore, the image forming apparatus 1 according to this embodiment employs a pressing mechanism 30 configured to be able to move the support position of the pressing roller 31 in the vertical direction. Under the control of the control unit 40, the pressing mechanism 30 adopts different support positions for the pressing roller 31 in the vertical direction during standby, during the conveying operation, and during the image forming operation.

[0048] Specifically, when the pressing mechanism 30 is on standby, the pressing roller 31 is completely separated from the conveyor belt 11. At this time, no pressing force is applied to the medium P by the weight of the pressing roller 31 (FIG. 6A). In this state, in preparation for the start of image formation, the medium P is introduced between the pressing roller 31 and the conveyor belt 11, and the adhesive 11a is applied to the conveyor belt 11.

[0049] During the conveying operation, the pressing mechanism 30 moves the pressing roller 31 downward from the standby state, and assumes a state in which all (or most) of the pressing force due to the weight of the pressing roller 31 is applied to the conveyor belt 11 between the pressing roller 31 and the pressure receiving member 32 (FIG. 6B). At this time, the pressing roller 31 is placed on the pressure receiving member 32.

[0050] As a result, the media P being transported by the transport belt 11 is adhered and fixed to the adhesive 11a on the transport belt 11. During the transport operation, the media P is constantly transported in the transport direction by the transport belt 11, so no pressure marks are generated.

[0051] During image formation, the pressure mechanism 30 moves the pressure roller 31 slightly upward from the time of the transport operation, so that the pressure roller 31 is in close proximity to (or in slight contact with) the media P (FIG. 6C). At this time, the pressure applied to the media P by the pressure roller 31 is zero or lower than the pressure due to the weight of the pressure roller 31.

[0052] If the pressure roller 31 were to be completely separated from the conveyor belt 11 during an image forming operation, as it is during standby, the pressure roller 31 would be raised significantly above the conveyor belt 11. During a print job, the medium P is wrapped around the pressure roller 31 and placed thereon with an appropriate amount of tension, and is placed on the conveyor belt 11 in a state where it is adhered and fixed by the adhesive 11a. Therefore, if the pressure roller 31 were to be raised significantly above the conveyor belt 11, a large back tension (i.e., a pulling force) would be applied to the medium P from the pressure roller 31. As a result, partial stretching would occur at the position of the medium P where it is introduced onto the conveyor belt 11, causing wrinkles.

[0053] For this reason, during image formation operations, the pressing mechanism 30 places the pressing roller 31 in close proximity to or in slight contact with the media P. However, from the perspective of suppressing expansion / contraction and positional misalignment of the media P even during image formation operations, it is preferable that a slight pressing force be applied from the pressing roller 31 to the media P. For this reason, it is preferable that the pressing mechanism 30 places the pressing roller 31 in slight contact with the media P even during image formation operations.

[0054] During this image forming operation, the conveying operation stops, so the pressure roller 31 comes into contact with the same point on the media P. In this state, however, the pressure applied to the media P by the pressure roller 31 becomes zero or extremely small, so the occurrence of pressure marks is avoided.

[0055] In this way, the pressing mechanism 30 according to this embodiment has the pressing roller 31 supported at different positions in the up-down direction during standby, during transport operation, and during image forming operation. That is, the pressing mechanism 30 according to this embodiment moves the support position of the pressing roller 31 so that the pressing roller 31 is at the top during standby, at the bottom during transport operation, and at an intermediate position between these two positions during image forming operation.

[0056] Hereinafter, the support position of the pressure roller 31 when the image forming apparatus 1 is on standby will also be referred to as the "standby position." Also, hereinafter, the support position of the pressure roller 31 when the image forming apparatus 1 is performing a conveying operation will also be referred to as the "pressing position." Also, hereinafter, the support position of the pressure roller 31 when the image forming apparatus 1 is performing an image forming operation will also be referred to as the "pressure suppressing position."

[0057] Fig. 7 is a diagram showing an example of the configuration of the support structure 33 of the pressing mechanism 30. The support structure 33 supports the pressing roller 31 and the pressure receiving member 32 on both sides in the width direction of the conveyor belt 11. Only the configuration on one side is shown in Figs. 7 and 8 below.

[0058] Fig. 8 is a diagram showing an example of the operation of the pressing mechanism 30. Fig. 8A, Fig. 8B, and Fig. 8C respectively show the states that the pressing mechanism 30 takes during the following operations. FIG. 8A: Image forming apparatus 1 is on standby (neither the conveying operation nor the image forming operation is being performed) FIG. 8B: During the conveying operation of the image forming apparatus 1 FIG. 8C: Image forming apparatus 1 during image forming operation

[0059] 8A, 8B, and 8C show the support structure 33 as viewed from the upstream side in the conveying direction, and the lower diagrams in 8A, 8B, and 8C show the rotational position of the eccentric cam 33d.

[0060] The support structure 33 of the pressing mechanism 30 includes a first support member 33a, a second support member 33e, a biasing spring 33b, an air cylinder 33c, an eccentric cam 33d, and a cam drive motor 33dd.

[0061] Here, the support structure 33 of the pressing mechanism 30 is configured to be attached to the housing 10a of the conveying mechanism 10. The housing 10a is a housing that supports the conveying belt 11 and extends along the conveying belt 11. Hereinafter, it will be abbreviated as "housing 10a."

[0062] The first support member 33a is a member that supports the pressure roller 31 on both sides of the media P so as to face the upper surface of the conveyor belt 11. The first support member 33a is supported by a biasing spring 33b and an air cylinder 33c so as to be movable up and down relative to the housing 10a. The first support member 33a is also disposed opposite an eccentric cam 33d attached to the housing 10a, and abuts against the eccentric cam 33d when the eccentric cam 33d is in a predetermined rotational position. That is, the first support member 33a moves up and down relative to the housing 10a (i.e., the conveyor belt 11) due to the biasing force received from the biasing spring 33b, the upward pushing force received from the air cylinder 33c, and the upward pushing force received from the eccentric cam 33d.

[0063] The biasing spring 33b has a first end (upper end) attached to the lower surface of the first support member 33a and a second end (lower end) attached to the upper surface of the housing 10a. The biasing spring 33b always exerts a biasing force on the first support member 33a to lift the first support member 33a upward. When the image forming apparatus 1 is on standby, the biasing force (reaction force) of the biasing spring 33b causes the pressure roller 31 to rise to the "standby position" (FIG. 8A). Note that the biasing spring 33b used has a biasing force (reaction force) greater than the weight of the pressure roller 31, for example.

[0064] The air cylinder 33c is an actuator that uses compressed air as a power source (not shown) to move its own piston up and down. The upper end of the piston of the air cylinder 33c is attached to the lower surface of the first support member 33a, and the lower end of the cylinder is attached to the upper surface of the housing 10a. The position of the air cylinder 33c is controlled by the control unit 40. Specifically, when the image forming apparatus 1 is on standby, the air cylinder 33c is placed with the piston pushed outward from within the cylinder. At this time, the air cylinder 33c is in a non-operating state and does not generate any external force.

[0065] On the other hand, air cylinder 33c operates to retract the piston into the cylinder during the transport operation and image forming operation of image forming apparatus 1. Then, air cylinder 33c operates to generate a force that presses down first support member 33a during the transport operation and image forming operation of image forming apparatus 1 (FIGS. 8B and 8C). In other words, during the transport operation and image forming operation of image forming apparatus 1, the downward force of air cylinder 33c cancels the reaction force of biasing spring 33b.

[0066] Here, during the conveying operation, the eccentric cam 33d is not in contact with the first support member 33a, so the first support member 33a moves downward due to the weight of the pressure roller 31, and the support position of the pressure roller 31 moves down to the "pressing position." As a result, the pressing force due to the weight of the pressure roller 31 is applied to the conveyor belt 11 and the pressure receiving member 32.

[0067] The eccentric cam 33d is attached to a bracket that stands on the top surface of the housing 10a and is disposed between the housing 10a and the first support member 33a. The eccentric cam 33d is attached to the bracket by a support pin so that it can rotate in a direction perpendicular to the conveyance direction (i.e., the width direction). Depending on its rotational position, the abutment surface of the eccentric cam 33d abuts against the abutment surface (i.e., the lower surface) of the first support member 33a, thereby pushing up the first support member 33a. The eccentric cam 33d is rotated by a cam drive motor 33dd connected to it.

[0068] The rotational position of eccentric cam 33d is controlled by control unit 40, which controls the operation of cam drive motor 33dd. Specifically, for example, when image forming apparatus 1 is on standby or performing a conveying operation, eccentric cam 33d takes a rotational position where its contact surface is out of contact with the contact surface of first support member 33a (hereinafter referred to as a non-contact rotational position). Then, for example, when image forming apparatus 1 is performing an image formation operation, eccentric cam 33d is rotated by cam drive motor 33dd, and its contact surface abuts against the contact surface of first support member 33a (hereinafter referred to as a contact rotational position). As a result, eccentric cam 33d exerts a force on first support member 33a to push up the first support member 33a. That is, when image forming apparatus 1 is performing an image formation operation, the support position of pressure roller 31, which has lowered to the "pressure position," is pushed up to the "pressure suppression position" by the pushing force of eccentric cam 33d (FIG. 8C).

[0069] The second support member 33e is a member that supports the pressure receiving member 32 so as to face the lower surface of the conveyor belt 11, and is attached to the side of the housing 10a.

[0070] With this configuration, the pressing mechanism 30 of this embodiment moves the support position of the pressing roller 31 to one of the "standby position," "pressing position," or "pressure suppression position" depending on the operating state of the image forming device 1.

[0071] That is, when the image forming apparatus 1 is on standby, the control unit 40 puts the air cylinder 33c in a non-operating state and the eccentric cam 33d in a non-contact rotation position, whereby the pressing mechanism 30 puts the pressing roller 31 in a state where it is raised to the "standby position" due to the reaction force of the biasing spring 33b (FIG. 8A).

[0072] Then, during the conveying operation of the image forming apparatus 1, the control unit 40 switches the air cylinder 33c to an operating state while maintaining the eccentric cam 33d in the non-contact rotation position, and the air cylinder 33c cancels the reaction force of the biasing spring 33b. As a result, the first support member 33a moves downward due to the weight of the pressure roller 31, and the support position of the pressure roller 31 moves down to the "pressing position" (FIG. 8B).

[0073] Then, the control unit 40 rotates the eccentric cam 33d to the contact rotation position while maintaining the air cylinder 33c in an operating state during image formation operation of the image forming apparatus 1. As a result, an upward force from the eccentric cam 33d acts on the first support member 33a, and the pressure roller 31 rises to the "pressure suppressing position" (FIG. 8C).

[0074] <Time chart of each part's operation> Next, an example of the operation of each unit of the image forming apparatus 1 according to this embodiment will be described.

[0075] 9 and 10 are time charts showing an example of the operation of each part controlled under the control of the control unit 40. Note that Fig. 9 shows the operation in the case of bidirectional printing, and Fig. 10 shows the operation in the case of unidirectional printing.

[0076] 9 and 10 show time charts of whether ink ejection (image forming operation) is being performed, whether the scanning operation of the head unit 21 is being performed, the speed of the conveyor belt 11 (conveying operation), and the support position of the pressure roller 31.

[0077] The image forming apparatus 1 according to this embodiment synchronously controls the image forming operation, the scanning operation of the head unit 21, the conveying operation, and the operation of the pressing mechanism 30 under the control of the control unit 40. That is, the image forming apparatus 1 according to this embodiment is characterized in that the support position of the pressing roller 31 is switched between the pressing position and the pressure suppressing position in synchronization with the intermittent belt conveying operation during printing.

[0078] 9, in bidirectional printing, ink is ejected and printing is performed during both forward and backward scans of the head unit 21. Therefore, belt transport is performed between each scan.

[0079] On the other hand, as shown in Figure 10, in unidirectional printing, ink is ejected and printed only during the normal forward scan. The backward scan is an operation to return to the initial position. The belt is transported only after the forward scan.

[0080] In both bidirectional printing and unidirectional printing, the operation of the pressing mechanism 30 is controlled by the control unit 40 as described above. That is, when the image forming apparatus 1 is on standby, the operation of the pressing mechanism 30 is controlled so that the pressing roller 31 is supported at the "standby position." When the image forming apparatus 1 is performing a conveying operation, the operation of the pressing mechanism 30 is controlled so that the pressing roller 31 is supported at the "pressing position." When the image forming apparatus 1 is performing an image formation operation, the operation of the pressing mechanism 30 is controlled so that the pressing roller 31 is supported at the "pressure suppressing position."

[0081] When switching from an image forming operation to a conveying operation, or when switching from a conveying operation to an image forming operation, it is desirable to consider the time it takes to switch the support position of the pressure roller 31 when determining the operation start timing for each section. That is, when switching from an image forming operation to a conveying operation, it is desirable to switch the support position of the pressure roller 31 immediately before the end of the image forming operation and immediately before the start of the conveying operation. Also, when switching from a conveying operation to an image forming operation, it is desirable to switch the support position of the pressure roller 31 immediately after the end of the conveying operation, and wait until the switch is complete before starting the image forming operation.

[0082] In this way, in the image forming apparatus 1 according to this embodiment, it is possible to prevent a large pressure from being continuously applied from the pressure roller 31 to the same location on the media P when transport is stopped. This makes it possible to suppress pressure marks.

[0083] <Effects> As described above, the image forming apparatus according to this embodiment a conveyance mechanism having a conveyance belt and an adhesive disposed on the conveyance belt, the conveyance mechanism conveying the medium on the conveyance belt while the medium is adhered to the adhesive; a pressure mechanism including a pressure roller disposed opposite the conveyor belt and pressing the medium against the conveyor belt, and a pressure receiving member disposed on the opposite side of the conveyor belt from the pressure roller; an image forming unit that forms an image on the medium; a control unit that controls the conveying mechanism and the image forming unit so that a conveying operation and an image forming operation are alternately and repeatedly performed, and that operates the pressing mechanism in conjunction with switching between the conveying operation and the image forming operation; Equipped with The control unit During the transport operation, the pressing mechanism is operated so that a pressing force due to the weight of the pressing roller is applied to the medium; During the image forming operation, the pressure mechanism is operated so that the pressure roller is kept in close proximity to the media and the pressure applied to the media is zero or less than the pressure due to the pressure roller's own weight.

[0084] Therefore, with the image forming apparatus according to this embodiment, it is possible to prevent the pressure of the pressure roller from being applied to the media due to its own weight (or to minimize the pressure) during image formation operations, which makes it possible to prevent the pressure of the pressure roller from being applied to the same position on the media for a long period of time due to its own weight, which would cause pressure marks to be left on the media.

[0085] In particular, in the image forming apparatus according to this embodiment, during image forming operation, the control unit operates the pressing mechanism so that the pressing roller is in contact with the media and the pressing force applied to the media is smaller than the pressing force due to the pressure roller's own weight.

[0086] This makes it possible to prevent pressure marks from being generated on the medium due to back tension from the pressure roller during image formation, and also to prevent expansion / contraction and positional deviation of the medium.

[0087] In particular, in the image forming apparatus according to this embodiment, an eccentric cam is used to support the pressure roller so that the support position of the pressure roller can be moved up and down.

[0088] By using an eccentric cam, it is possible to adjust the support position of the pressure roller with high precision while suppressing product costs. In addition, this makes it possible to quickly switch the support position of the pressure roller between the pressing position and the pressure suppression position. In other words, this makes it possible to prevent the imaging time from increasing due to the state switching of the pressure mechanism.

[0089] (Second embodiment) In the first embodiment, the pressing mechanism 30 is configured such that the support position of the pressing roller 31 is raised upward when changing from the state during the conveying operation to the state during the image forming operation.

[0090] The configuration shown in the first embodiment is useful in that the pressure applied to the medium P and adhesive 11a can be made almost zero at the pressure suppression position. However, with this configuration, the pressure roller 31 is moved up and down between the pressure position and the pressure suppression position during printing, which may cause wrinkles in the medium P depending on the back tension of the pressure roller 31. Furthermore, since the thickness of the medium P varies depending on the type of medium P (for example, approximately 100 μm to 5 mm), fine adjustment is required to position the pressure roller 31 so that it slightly contacts the medium P.

[0091] From this viewpoint, the pressing mechanism 30 according to this embodiment is configured to move the support position of the pressure receiving member 32 downward when changing from the state during the conveying operation to the state during the image forming operation.

[0092] 11A, 11B, and 11C are diagrams showing the states of the pressing mechanism 30 during each operation (standby, transport operation, and image forming operation) of the image forming apparatus 1. FIGS. 11A, 11B, and 11C respectively show the states of the pressing mechanism 30 during the following operations. FIG. 11A: Image forming apparatus 1 is on standby (neither the conveying operation nor the image forming operation is being performed) FIG. 11B: During the conveying operation of the image forming apparatus 1 FIG. 11C: Image forming operation of image forming apparatus 1

[0093] Specifically, the pressing mechanism 30 is in the same state as in the first embodiment during standby and conveying operation. That is, during standby, the pressing mechanism 30 is in a state in which the pressing roller 31 is completely separated from the conveyor belt 11 (FIG. 11A).

[0094] During the conveying operation, the pressing mechanism 30 moves the pressing roller 31 downward from its standby position, so that all of the pressing force due to the pressing roller 31's own weight is applied to the conveying belt 11 (i.e., the media P) between the pressing roller 31 and the pressure receiving member 32 (Figure 11B).

[0095] However, when switching from the conveying operation to the image forming operation, the pressing mechanism 30 according to this embodiment moves the pressure receiving member 32 from the normal position to the lower release position (FIG. 11C), so that the pressure receiving member 32 is completely separated from the conveyor belt 11.

[0096] At this time, the pressure receiving member 32 moves from the normal position to the release position, and the pressure roller 31 also moves down. However, at this time, the first support member 33a supporting the pressure roller 31 hits the stopper 33g (see FIG. 12), so the pressure roller 31 stops at a position slightly lower than the pressing position (=lower limit position).

[0097] At this time, most of the weight of the pressure roller 31 is received by the stopper 33g, but because the pressure roller 31 has moved from the normal position to the lower limit position, the pressure roller 31 slightly presses down on the conveyor belt 11. As a result, the pressing force due to the weight of the pressure roller 31 is applied to the conveyor belt 11 (i.e., the media P) in a state where the pressure receiving member 32 is not present on the back side of the conveyor belt 11, and the conveyor belt 11 bends downward due to elastic deformation.

[0098] As a result, the media P receives a pressing force from the pressure roller 31 that corresponds to the reaction force of the conveyor belt 11. However, this pressing force is much smaller than during the conveying operation, and does not contribute to the creation of pressure marks.

[0099] In this embodiment, the position of the pressure receiving member 32 during the transport operation is referred to as the "normal position" (FIG. 11B), and the position of the pressure receiving member 32 during the image forming operation is referred to as the "release position" (FIG. 11C).

[0100] 11C, the support position of the pressure roller 31 during image formation is depicted as a "lower limit position" that is slightly lower than the "pressing position." As described above, this represents the position where the first support member 33a that supports the pressure roller 31 abuts against the stopper 33g (see FIG. 12).

[0101] With the pressure mechanism 30 according to this embodiment, when switching between the conveying operation and the image forming operation, there is no need to move the support position of the pressure roller 31 up and down between the pressing position and the pressure suppressing position. This makes it less likely that wrinkles will occur in the media P due to back tension of the pressure roller 31. Furthermore, there is no need to adjust the position of the pressure roller 31 each time for each type of media P, taking into account its thickness.

[0102] However, in the configuration of the pressing mechanism 30 according to this embodiment, a slight pressing force is applied to the medium P due to the reaction force of the conveyor belt 11 even during the image forming operation.

[0103] Fig. 12 is a diagram showing an example of the configuration of the support structure 33 of the pressing mechanism 30 according to this embodiment, and Fig. 13 is a diagram showing an example of the operation of the pressing mechanism 30 according to this embodiment.

[0104] The pressing mechanism 30 according to this embodiment can be configured by, for example, a first support member 33a, a second support member 33e, a biasing spring 33b, an air cylinder 33c, an eccentric cam 33f, a cam drive motor 33ff, and a stopper 33g.

[0105] The basic configurations of the first support member 33a, the second support member 33e, the biasing spring 33b, and the air cylinder 33c are the same as those shown in the first embodiment. However, in the pressing mechanism 30 according to this embodiment, when switching from the conveying operation to the image forming operation, the eccentric cam 33f is used to switch the pressure receiving member 32 from the normal position to the release position.

[0106] That is, the eccentric cam 33f is attached to a bracket that protrudes from the side surface of the housing 10a, and is disposed so as to support from below the second support member 33e that supports the pressure receiving member 32. The eccentric cam 33f is attached to the bracket by a support pin so as to be rotatable in a direction perpendicular to the conveyance direction (i.e., the width direction). The eccentric cam 33f can move the second support member 33e up and down along the outer shape of its contact surface according to its own rotational position. The eccentric cam 33f is rotated by a cam drive motor 33ff connected to it.

[0107] The rotational position of eccentric cam 33f is controlled by control unit 40, which controls the operation of cam drive motor 33ff. Specifically, eccentric cam 33f takes a rotational position such that pressure receiving member 32 is located at a normal position, for example, when image forming apparatus 1 is on standby or performing a conveying operation. Then, when image forming apparatus 1 is performing an image formation operation, eccentric cam 33f is rotated by cam drive motor 33ff, and takes a rotational position such that pressure receiving member 32 is located at a release position.

[0108] In the pressing mechanism 30 according to this embodiment, when the image forming apparatus 1 is in a standby state, the pressing roller 31 is placed in a "standby position." When the image forming apparatus 1 is performing a conveying operation, the pressing roller 31 is placed in a "pressing position." This is the same as in the first embodiment.

[0109] The stopper 33g is a protrusion formed to stand upright from the upper surface of the housing 10a. The stopper 33g is disposed so as to face the lower surface of the first support member 33a that supports the pressure roller 31. The stopper 33g is formed at an appropriate height so that when the pressure receiving member 32 moves from the normal position to the release position during image formation operation, the pressure roller 31 will abut against the first support member 33a that supports the pressure roller 31 as it tries to lower. In other words, the stopper 33g is disposed so that the pressure roller 31 will stop at an appropriate position (lower limit position) when the pressure receiving member 32 moves to the release position.

[0110] As described above, the image forming apparatus 1 according to this embodiment can also minimize the pressing force of the pressure roller 31 on the media P due to its own weight during image formation. This makes it possible to prevent pressure marks from being left on the media P.

[0111] In this embodiment, the lower limit position of the pressure roller 31 is adjusted by the stopper 33g, but instead, the lower limit position of the pressure roller 31 may be adjusted by adjusting the downward pressure force of the air cylinder 33c, etc.

[0112] (Third embodiment) In the first embodiment, the configuration of the pressing mechanism 30 is such that, when changing from the state during the conveying operation to the state during the image forming operation, the support position of the pressing roller 31 is lifted upward using the rotational movement of the eccentric cam 33d.

[0113] In realizing the pressing mechanism 30 according to the present disclosure, means other than the eccentric cam 33d may be used as means for moving the support position of the pressing roller 31 up and down.

[0114] FIG. 14 is a diagram showing an example of the configuration of the support structure 33 of the pressing mechanism 30 according to this embodiment.

[0115] In this embodiment, a stepping motor 33h with a ball screw is used as a means for vertically moving the support position of the pressure roller 31 of the pressure mechanism 30. The stepping motor 33h is useful as a configuration for finely adjusting the support position of the pressure roller 31, similar to the eccentric cam 33d.

[0116] That is, for example, when the image forming apparatus 1 is on standby or performing a conveying operation, the stepping motor 33h is in a state where its contact surface is out of contact with the contact surface of the first support member 33a. And, for example, when the image forming apparatus 1 is performing an image forming operation, the stepping motor 33h is in a state where its contact surface abuts against the contact surface of the first support member 33a. As a result, during the image forming operation, the stepping motor 33h applies a force to the first support member 33a to push the first support member 33a upward. That is, during the image forming operation, the support position of the pressure roller 31, which has lowered to the "pressure position," is pushed up to the "pressure suppression position" by the pushing force of the stepping motor 33h (FIG. 8C).

[0117] As described above, the image forming apparatus 1 according to this embodiment can also minimize the pressing force of the pressure roller 31 on the media P due to its own weight during image formation. This makes it possible to prevent pressure marks from being left on the media P.

[0118] However, from the viewpoint of high-speed operation and parts cost, the eccentric cam 33d shown in the first embodiment is more useful than the stepping motor 33h.

[0119] (Fourth embodiment) In the first embodiment, the configuration of the pressing mechanism 30 is such that, when changing from the state during the conveying operation to the state during the image forming operation, the support position of the pressing roller 31 is lifted upward using the rotational movement of the eccentric cam 33d.

[0120] Media P come in a variety of thicknesses depending on the type. Therefore, if the distance between the pressure roller 31 and the conveyor belt 11 during image formation is fixed, there is a risk that excessive pressure due to the weight of the pressure roller 31 may be applied to the media P even during image formation.

[0121] From this perspective, the pressing mechanism 30 according to this embodiment is configured so that the distance between the pressing roller 31 and the conveyor belt 11 during the image forming operation can be adjusted.

[0122] FIG. 15 is a diagram showing an example of the configuration of the support structure 33 of the pressing mechanism 30 according to this embodiment.

[0123] The eccentric cam 33d according to this embodiment is disposed so that its support position in the vertical direction can be adjusted. Fig. 15 shows an embodiment in which a support position adjustment mechanism 33da for the eccentric cam 33d is provided on a bracket that attaches the eccentric cam 33d to the housing 10a. For example, the support position adjustment mechanism 33da is configured so that the position at which the eccentric cam 33d is pinned to the bracket can be changed.

[0124] As described above, according to the image forming apparatus 1 of this embodiment, the support position of the pressure roller 31 can be adjusted to accommodate media P of various thicknesses. This makes it possible to prevent excessive pressure from being applied to the media P due to the weight of the pressure roller 31 during image formation operations.

[0125] (Fifth embodiment) In each of the above embodiments, the image forming apparatus 1 according to the present disclosure is applied to a scan-type inkjet printer.

[0126] However, the image forming apparatus 1 according to the present disclosure can also be applied to a screen textile printing machine. That is, a screen textile printing machine is no different from a scan-type inkjet printer in that it applies an adhesive to a conveyor belt and applies pressure to the media against the adhesive with a pressure roller before printing. That is, when the image forming apparatus 1 according to the present disclosure is applied to a screen textile printing machine, the image forming unit 20 should be configured to be suitable for the screen printing method.

[0127] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Industrial Applicability]

[0128] According to the image forming apparatus of the present invention, it is possible to prevent pressure marks from being left on the medium. [Explanation of symbols]

[0129] 1. Image forming device 10. Conveying mechanism 10a housing 11 Conveyor belt 11a adhesive 11b, 11c Conveyor rollers 12 Guide roller 13 Delivery machine 14 Peeling roller 15 Winder 20 Image forming unit 21 Head Unit 22 Head support 30 Pressing mechanism 31 Pressure roller 31a Heater 32 Pressure receiving member 33 Support structure 33a first support member 33c Air Cylinder 33d, 33f eccentric cam 33dd, 33ff cam drive motor 33e second support member 33g stopper 33h Stepping motor 33da Support position adjustment mechanism 40 Control Unit 50 Head drive unit 60 Conveyor drive unit 70 Image processing section 80 Input / Output Interface P Media

Claims

1. a conveyance mechanism having a conveyance belt and an adhesive disposed on the conveyance belt, the conveyance mechanism conveying the medium on the conveyance belt while the medium is adhered to the adhesive; a pressure mechanism including a pressure roller disposed opposite the conveyor belt and pressing the medium against the conveyor belt, and a pressure receiving member disposed on the opposite side of the conveyor belt from the pressure roller; an image forming unit that forms an image on the medium; a control unit that controls the conveying mechanism and the image forming unit so that a conveying operation and an image forming operation are alternately and repeatedly performed, and that operates the pressing mechanism in conjunction with switching between the conveying operation and the image forming operation; Equipped with The control unit During the transport operation, the pressing mechanism is operated so that a pressing force due to the weight of the pressing roller is applied to the medium; During the image forming operation, the pressure mechanism is operated so that the pressure roller is kept close to the medium and the pressure applied to the medium is zero or smaller than the pressure due to the pressure roller's own weight. Image forming device.

2. The control unit operates the pressing mechanism during the image forming operation so that the pressing roller is in contact with the medium and the pressing force applied to the medium is smaller than the pressing force due to the weight of the pressing roller. The image forming apparatus according to claim 1 .

3. The transport mechanism wraps the medium around the pressure roller and places the medium on the transport belt while applying an appropriate tension to the medium. The image forming apparatus according to claim 1 .

4. The pressure roller has a built-in heater, and is configured so that when the medium is pressed against the conveyor belt, the heat generated by the heater can raise the temperature of the medium. The image forming apparatus according to claim 1 .

5. the pressing mechanism supports the pressing roller or the pressure receiving member so that the support position thereof can be moved up and down; The control unit moves the support position of the pressure roller or the pressure receiving member up and down when switching between the transport operation and the image forming operation. The image forming apparatus according to claim 1 .

6. the pressing mechanism has an eccentric cam disposed so as to be able to come into contact with the pressing roller or a support member that supports the pressure receiving member, When switching between the conveying operation and the image forming operation, the control unit rotates the eccentric cam to move the support position of the pressure roller or the pressure receiving member up and down. The image forming apparatus according to claim 5 .

7. The pressing mechanism is configured so that the distance between the pressing roller and the conveying belt during the image forming operation can be adjusted. The image forming apparatus according to claim 1 .

8. The control unit operates the pressing mechanism so that the pressing roller is completely separated from the conveying belt during the conveying operation or during a standby state other than the image forming operation. The image forming apparatus according to claim 1 .

9. The control unit operates the pressing mechanism in synchronization with a timing at which the conveying operation and the image forming operation are switched. The image forming apparatus according to claim 1 .

10. The pressure receiving member is a backup roller or a backup plate. The image forming apparatus according to claim 1 .

11. The pressure receiving member is disposed at a position that is at least the radius of the conveying roller from the position of the conveying roller around which the conveying belt is stretched. The image forming apparatus according to claim 1 .

12. The medium is a fabric. The image forming apparatus according to claim 1 .

13. Applied to scanning inkjet printers The image forming apparatus according to claim 1 .

14. Applied to screen printing machines The image forming apparatus according to claim 1 .

Images