JP2014040016A - Recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus capable of suppressing creases, floating, and elongation of a recording medium by exerting sufficient back tension on the recording medium to make the recording medium closely adhere to a recording medium conveyance drum.SOLUTION: A recording apparatus includes a recording head (an inkjet recording head 3) for recording an image, a recording medium conveyance drum 5 for conveying a recording medium 4 with a leading edge of the recording medium 4 retained therein, and a pressing roller 8 for pressing the recording medium 4 against the recording medium conveyance drum 5. The recording apparatus further includes a driving unit (a driving motor) that rotates the pressing roller 8 at a speed lower than a rotation speed of the recording medium conveyance drum 5, and a torque limiter connected between the pressing roller 8 and the driving unit.

Description

  The present invention relates to a recording apparatus such as an inkjet recording apparatus.

  Japanese Patent Application Laid-Open No. 2004-151867 discloses a direct recording type inkjet recording apparatus (sheet-fed rotary printing machine) that directly records characters and images on recording media such as paper, cloth, and plastic sheets. This ink jet recording apparatus is arranged with a recording medium transport drum (conveyance cylinder) for transporting a recording medium and an ink jet head (printing) disposed toward the recording medium transport drum and ejecting ink onto the recording medium on the circumference of the recording medium transport drum. Head). The holding device provided on the recording medium transport drum holds only the leading end of the recording medium and the recording medium transport drum rotates, thereby transporting the recording medium in close contact with the recording medium transport drum.

  Further, Patent Document 2 discloses a transfer-type ink jet recording apparatus that forms characters and images on an intermediate transfer member and transfers the characters and images from the intermediate transfer member to a recording medium. The inkjet recording apparatus is formed to be rotatable, and is disposed close to the outer peripheral surface of the intermediate transport body and an intermediate transport body that transfers the recording medium to the recording medium transport drum (drawing drum). And a conveyance guide for applying a negative pressure to the recording medium. In this ink jet recording apparatus, a negative pressure is applied to a recording medium on the circumference of the intermediate transport body from a suction hole provided in the transport guide.

JP 2002-292956 A JP 2009-220954 A

  In the invention disclosed in Patent Document 1, the leading edge of the recording medium is sucked and held on the recording medium transport drum, but the trailing edge is not sucked and held. For this reason, there is a problem that back tension is not applied to the recording medium, and the recording medium is wrinkled or floated.

  Furthermore, in the ink jet recording apparatus, it is desirable to bring the ink jet head and the recording medium as close as possible in order to eject ink to an accurate position of the recording medium. For this reason, it is desirable that the gripping device provided on the recording medium conveyance drum is arranged inside the recording medium conveyance drum so as not to protrude outside the outer periphery of the recording medium conveyance drum in order to avoid interference with the inkjet head. . However, when the holding device is inside the recording medium conveyance drum, the portion following the leading end of the recording medium held by the holding device inside the recording medium conveyance drum is not bent at the outer periphery of the drum due to rigidity. For this reason, after floating up to the outside of the outer periphery of the recording medium transport drum, it is held along the outer peripheral surface of the recording medium transport drum.

  If the recording medium is wrinkled or floated when ink is ejected, in the direct recording system, there is a possibility that the landing accuracy may be poor because the ink is not accurately applied to a predetermined position of the recording medium. Further, the recording medium may come into contact with the ink jet head, and there is a possibility that either one or both of the ink jet head and the recording medium may be scratched, and the ink applied to the recording medium may be rubbed or swollen.

  In the invention disclosed in Patent Document 2, a sufficient negative pressure can be applied to the recording medium when the contact area between the recording medium and the conveyance guide is wide. However, when the portion of the recording medium that has been transferred from the intermediate conveyance body to the recording medium conveyance drum becomes large and the contact area between the recording medium and the conveyance guide becomes narrow, the conveyance guide applies sufficient negative pressure to the recording medium. It becomes impossible. For this reason, sufficient back tension is not applied to the recording medium, and the recording medium is wrinkled and floated. In the transfer system, if the recording medium is wrinkled or lifted at the transfer section where the intermediate transfer member transfers characters or images to the recording medium, the recording position accuracy will not be correctly transferred to the target position. To do. Further, the recording medium is folded when the recording medium is folded and drawn into the intermediate transfer member and the recording medium transport drum.

  On the other hand, in the configuration of Patent Document 2, if the suction force of the transport guide is increased so that a sufficient negative pressure acts even if the contact area between the recording medium and the transport guide becomes narrow, the negative pressure on the recording medium is increased. Increases the excessive back tension. As a result, there is a problem that elongation occurs in the recording medium.

  Accordingly, an object of the present invention is to solve the above-described problems, and to apply a sufficient back tension to the recording medium so that the recording medium is in close contact with the recording medium conveyance drum, thereby suppressing wrinkling, floating and elongation of the recording medium. It is to provide an ink jet recording apparatus.

  In order to achieve the above-described object, the present invention provides a recording head for recording an image, a recording medium conveyance drum that conveys the recording medium while holding the tip of the recording medium, and a pressing roller that presses the recording medium against the recording medium conveyance drum And a drive unit that rotates the pressure roller at a speed slower than the rotation speed of the recording medium transport drum, and a torque limiter connected between the pressure roller and the drive unit.

  According to the present invention, when the pressing roller applies a back tension to the recording medium, the recording medium comes into close contact with the recording medium conveyance drum, and the occurrence of wrinkling and floating of the recording medium can be suppressed. As a result, ink can be accurately ejected onto the recording medium, and images and characters can be transferred, and the quality of images and characters formed on the recording surface of the recording medium is improved. Further, when the back tension applied to the recording medium increases, the torque limiter connected to the pressing roller acts and the speed of the pressing roller becomes the same as that of the recording medium transport drum, so that the back tension applied to the recording medium is reduced. It is corrected to a predetermined value. Therefore, the elongation of the recording medium can be suppressed.

It is sectional drawing of the inkjet recording device using the transfer system of this invention. In the inkjet recording apparatus of the present invention shown in FIG. 1a, FIG. In the ink jet recording apparatus of the present invention shown in FIG. 1a, it is a main part enlarged view showing a state in which the floating generated in the recording medium is eliminated by back tension. FIG. 3 is a cross-sectional view illustrating a recording medium conveyance drum, a pressure roller, a torque limiter, a connection gear, and a drive unit according to the present invention. FIG. 1B is a cross-sectional view showing a recording medium transport drum, a pressure roller, a torque limiter, a connecting gear, and a drive unit of the present invention in the state shown in FIG. 1B. It is a block diagram showing a control system of an ink jet recording apparatus using the transfer system of the present invention. It is sectional drawing which shows the implementation state whose press roller of this invention is reverse crown shape. It is sectional drawing of the inkjet recording device using the direct recording system of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1A is a cross-sectional view schematically showing a transfer type ink jet recording apparatus used in the first embodiment of the present invention, and FIG. 1B is an enlarged view of a main part thereof.

  The ink jet recording apparatus includes a rotatable intermediate transfer drum 1, an ink jet recording head 3, a moisture removal promoting device 6, a recording medium transport drum 5, and a cleaning device 7, which are positioned around the intermediate transfer drum 1, respectively. A coating device 2 is provided. Further, as shown in an enlarged view in FIG. 1 b, a press roller 8 and an intermediate transport drum 9 are disposed around the recording medium transport drum 5.

  The ink jet recording head 3 has a plurality of nozzle rows in a direction orthogonal to the rotation direction of the intermediate transfer drum 1. Specifically, the inkjet recording head 3 includes a black ink discharge nozzle row 3a, a cyan ink discharge nozzle row 3b, a magenta ink discharge nozzle row 3c, and a yellow ink discharge nozzle row 3d. Each ink is ejected toward the intermediate transfer drum 1. The moisture removal promoting device 6 removes moisture on the circumference of the intermediate transfer drum 1. The cleaning device 7 cleans the intermediate transfer drum 1 to wash away ink on the peripheral surface of the intermediate transfer drum 1. The coating device 2 applies an image fixing component (for example, a mixture of a polyvalent metal salt and a water-soluble organic solvent) for fixing ink on the peripheral surface of the intermediate transfer drum 1. The intermediate conveyance drum 9 is rotatable while being in contact with the recording medium conveyance drum 5, and transfers the recording medium 4 supplied from a paper feeding mechanism (not shown) to the recording medium conveyance drum 5. The recording medium transport drum 5 has a gripping claw 15 capable of gripping the tip of the recording medium 4 on the outer peripheral portion, and rotates while holding the recording medium 4 delivered from the intermediate transport drum 9 on the peripheral surface. Thus, the recording medium 4 is conveyed so as to pass through a position in contact with the intermediate transfer drum 1. The pressing roller 8 has a central axis parallel to the rotation axis of the recording medium conveyance drum 5, and can rotate while being in contact with the recording medium conveyance drum 5.

  FIG. 2a shows a drive unit for the recording medium transport drum 5 and the pressure roller 8 of the ink jet recording apparatus. As shown in FIG. 2a, the pressing roller 8 is connected to a torque limiter 10 that interrupts transmission of torque when a torque of a predetermined value or more is applied. The torque limiter 10 is connected to a pressing roller drive motor 13 that generates a rotational motion via connecting gears 11 and 12.

  FIG. 3 is a block diagram showing a control system for controlling the ink jet recording apparatus of the present embodiment.

  The control unit 20 for sending drive control signals for each member includes a CPU 20a that is a central processing unit, a ROM 20b that is a read-only memory, a RAM 20c that is a read / write memory, and a counter 20d that counts drive pulses and the like. doing. The CPU 20a reads a program and various data from the ROM 20b, etc., performs necessary calculations and determinations, and controls each member. The ROM 20b stores various programs necessary for the operation of the CPU 20a and various data necessary for recording such as character codes and dot patterns. The RAM 20c is a working area for temporarily storing data and calculation results being instructed by the CPU 20a, or a buffer area for storing various data input to the control unit 20 from the external device 21 or the like. It is made up of. The counter 20d counts the number of drive pulses of the intermediate transfer drum drive motor 27 that rotates the intermediate transfer drum 1, and transmits the information to the CPU 20a.

  The control unit 20 is connected to a recording medium detection sensor 31, an external device 21 such as a personal computer, a head driver 23, and motor drivers 24, 26, 28, and 29 via an interface 22. The recording medium detection sensor 31 detects the presence of the recording medium 4 on the circumference of the recording medium transport drum 5. The external device 21 sends image data or the like as a signal to the control unit 20. The head driver 23 drives the inkjet recording head 3 (see FIG. 1a). The motor driver 24 drives a recording medium conveyance drum drive motor 25 that rotates the recording medium conveyance drum 5 (see FIGS. 1a, 1b, and 2). The motor driver 26 drives an intermediate transfer drum drive motor 27 that rotates the intermediate transfer drum 1 (see FIGS. 1a and 1b). The motor driver 28 drives the pressure roller drive motor 13 that rotates the pressure roller 8 (see FIGS. 1a, 1b, and 2). The motor driver 29 drives an intermediate transport drum drive motor 30 that rotates the intermediate transport drum 9 (see FIGS. 1a and 1b).

  A method of performing transfer type recording by the ink jet recording apparatus having the configuration described above will be described.

  When a recording start command and image data are transmitted from the external device 21 to the control unit 20 via the interface 22, the CPU 20 a drives the intermediate transfer drum drive motor 27 using the motor driver 26 to move the intermediate transfer drum 1. Rotate. As the intermediate transfer drum 1 rotates, the cleaning device 7 cleans the outer peripheral surface of the intermediate transfer drum 1, and the coating device 2 applies an image fixing component onto the outer peripheral surface of the intermediate transfer drum 1. Further, the CPU 20 a uses the head driver 23 to eject ink from the inkjet recording head 3 onto the outer peripheral surface of the intermediate transfer drum 1 that has been cleaned and applied with the image fixing component, and image data supplied from the external device 21. Characters and images based on Thereafter, the moisture removal promoting device 6 removes moisture in the ink ejected on the outer peripheral surface of the intermediate transfer drum 1.

  On the other hand, according to the recording start command, the recording medium 4 is supplied onto the outer peripheral surface of the intermediate transport drum 9 from a paper feeding mechanism (not shown). The CPU 20 a drives the intermediate transport drum drive motor 30 using the motor driver 29 to rotate the intermediate transport drum 9, and the recording medium 4 is transported along the outer peripheral surface of the intermediate transport drum 9. The recording medium 4 supplied onto the outer peripheral surface of the intermediate transport drum 9 is gripped at the tip by a gripping claw 15 at a contact point with the recording medium transport drum 5, so that the intermediate transport drum 9 moves to the recording medium transport drum 5. Delivered. The recording medium transport drum 5 is rotated by the CPU 20 a driving the recording medium transport drum driving motor 25 using the motor driver 24 and the tip of the recording medium 4 is gripped by the gripping claws 15. It is held on the outer peripheral surface and conveyed. At this time, the CPU 20 a drives the pressing roller driving motor 13 using the motor driver 28 to rotate the pressing roller 8, and the recording medium 4 is pressed onto the outer peripheral surface of the recording medium transport drum 5. The recording medium 4 pressed on the outer peripheral surface of the recording medium transport drum 5 in this way is pressed against the outer peripheral surface of the intermediate transfer drum 1 on which characters and images are formed. As a result, characters and images formed on the outer peripheral surface of the intermediate transfer drum 1 are copied onto the recording medium 4. The recording medium 4 onto which the characters and images are transferred in this way is discharged from the outer peripheral surface of the recording medium transport drum 5 to the outside of the ink jet recording apparatus by a discharge mechanism (not shown). Further, the outer peripheral surface of the intermediate transfer drum 1 after the transfer is completed is cleaned by the cleaning device 7 and the ink is washed away, and the image fixing component is applied by the coating device 2 to prepare for the next recording.

  In this recording method, the recording medium 4 is conveyed to a character or image transfer position, that is, a contact point with the intermediate transfer drum 1 through a drum nip portion 16 sandwiched between the recording medium conveyance drum 5 and the pressing roller 8. . In the present embodiment, the recording medium transport drum 5 rotates at a rotational speed V1, and the pressing roller 8 rotates at a rotational speed V2 that is slower than V1. Since the recording medium 4 rotates on the outer periphery of the recording medium conveyance drum 5 at the same rotational speed V1 as that of the recording medium conveyance drum 5, the pressure roller 8 is relatively opposite to the recording medium 4 in the direction opposite to the conveyance direction. A force, that is, a frictional force toward the rear (upstream side) in the transport direction is applied to the recording medium 4. This frictional force serves as a back tension that urges the recording medium 4 toward the rear in the transport direction. Due to the back tension, the recording medium 4 is pulled without slack, so that the recording medium 4 is brought into close contact with the outer peripheral surface of the recording medium transport drum 5 and does not wrinkle or float. In order to generate the back tension, the friction coefficient between the recording medium transport drum 5 and the recording medium 4 needs to be set smaller than the friction coefficient between the pressing roller 8 and the recording medium 4. At this time, the following equation holds.

Friction coefficient between recording medium transport drum 5 and recording medium 4: μ
Friction coefficient between the pressure roller 8 and the recording medium 4: μ ′
Back tension applied to the recording medium 4: Fb
Vertical drag generated at the drum nip 16: N
Conveying force of the recording medium conveying drum 5 transmitted to the recording medium 4 through the gripping claws 15: Fd
μ <μ '
Fb = N × μ ′ = Fd + N × μ
V1> V2
FIGS. 1 b and 2 b show the ink jet recording apparatus when the rotation speed of the pressing roller 8 is changed to V2 ′ due to the torque limiter 10 acting due to the increase of the back tension applied to the recording medium 4. .

  The recording medium 4 is given a conveying force in the conveying direction from the recording medium conveying drum 5 via the gripping claw 15, and this conveying force is opposite to the back tension applied to the recording medium 4 by the pressing roller 8. It is power. For this reason, when the back tension generated by the pressing roller 8 increases, the recording medium 4 extends. Therefore, in the present invention, when the back tension applied to the recording medium 4 by the pressing roller 8 increases, the torque applied to the pressing roller 8 exceeds the limiter torque of the torque limiter 10 connected to the pressing roller 8, and the torque limiter 10. Is designed to slide at the connection with the shaft. When the torque limiter 10 acts, the rotational driving force transmitted by the pressing roller driving motor 13 via the coupling gears 11 and 12 is not transmitted to the pressing roller 8. Therefore, the active rotational drive of the pressing roller 8 is stopped, and the rotational speed V2 ′ of the pressing roller 8 rotates at a rotational speed equal to the rotational speed V1 of the recording medium transport drum 5 that is in contact with the recording medium 4. . At this time, since the rotation speeds of the pressing roller 8 and the recording medium transport drum 5 are the same, no force is generated on the recording medium 4 in the rearward direction in the transport direction due to friction, and no back tension is applied to the recording medium 4. At this time, the following equation holds.

Limiter torque of torque limiter 10: T
Radius of the pressing roller 8: r
T ≦ N × μ ′ × r
V1 = V2 '
Fb = 0
However, if the torque applied to the torque limiter 10 is reduced after the torque applied to the pressure roller 8 exceeds the limiter torque and then the torque applied to the torque limiter 10 decreases, the pressure roller drive motor 13 and the torque limiter are connected via the connecting gears 11 and 12. 10 connects again. As a result, the pressing roller 8 starts to actively rotate again, and the rotational speed of the pressing roller 8 becomes slower than the rotational speed of the recording medium transport drum 5, whereby back tension is applied to the recording medium 4.

  FIG. 1 c shows the ink jet recording apparatus when the recording medium 4 is lifted in the intermediate region 17 between the gripping claw 15 and the drum nip portion 16.

When the recording medium 4 floats in the intermediate area 17, the conveying force transmitted from the recording medium conveying drum 5 to the recording medium 4 via the gripping claws 15 is applied to the recording medium 4 in the drum nip portion 16. Is not transmitted until the floating of the recording medium 4 in the intermediate area 17 is resolved. If the conveying force is not transmitted to the recording medium 4, the torque limiter 10 does not act because a large torque is not generated in the pressing roller 8. Therefore, when the intermediate area 17 is floating, the pressing roller 8 rotates at a rotational speed V2 that is slower than the rotational speed V1 of the recording medium transport drum 5. Accordingly, the recording medium 4 in the intermediate area 17 is conveyed at a speed of V3 toward the rear in the conveying direction as a relative speed. As a result, the floating of the recording medium 4 proceeds toward the drum nip portion 16 at the relative speed V3, the floating of the recording medium 4 is eliminated, and the recording medium 4 comes into close contact with the circumference of the recording medium conveying drum 5. In addition, after the floating of the recording medium 4 is eliminated, a force is generated on the recording medium 4 toward the rear in the transport direction generated by friction on the recording medium 4 according to the principle described above. Since this force acts toward the rear in the conveyance direction of the recording medium 4, back tension is applied to the recording medium 4. As a result, the recording medium 4 is brought into close contact with the outer peripheral surface of the recording medium transport drum 5, and wrinkling and floating of the recording medium 4 can be suppressed. At this time, the following equation holds.
Fd = 0
V3 = V1-V2
N × μ <N × μ '

(Second Embodiment)
FIG. 4 is a cross-sectional view showing a structure that generates rotational driving in a transfer-type ink jet recording apparatus used in the second embodiment of the present invention.

  In the present embodiment, the ink jet recording apparatus has an outer diameter that continuously increases from the recording medium transport drum 5 and the relatively narrow diameter center portion toward both relatively thick diameter end portions. An inverse crown-shaped pressing roller 14 having a cylindrical shape is included. The reverse crown-shaped pressing roller 14 is connected to the torque limiter 10, and the torque limiter 10 is connected to the pressing roller driving motor 13 via the coupling gears 11 and 12.

  Since the reverse crown-shaped pressing roller 14 has a larger outer diameter at both end portions than the central portion, the pressure that the recording medium 4 receives from both end portions of the reverse crown-shaped pressing roller 14 is increased. Can be strongly pressed against the recording medium transport drum 5. Further, since the reverse crown-shaped pressing roller 14 presses the recording medium 4 at both ends, the recording medium 4 can be given a force for stretching the recording medium 4 in the direction of the arrow in FIG. As a result, it is possible to apply tension to the recording medium 4 in the direction orthogonal to the back tension. Therefore, wrinkles and floating of the recording medium 4 can be suppressed.

  In each of the above embodiments, the transfer type ink jet recording apparatus having the intermediate transfer drum 1 is used. However, as shown in FIG. 5, the ink is directly ejected to the recording medium 4 conveyed by the recording medium conveyance drum 5. You may use for the inkjet recording apparatus of a direct recording system. By using the direct recording type ink jet recording apparatus, it is not necessary to use the intermediate transfer drum 1, the coating apparatus, the moisture removal promoting apparatus, or the cleaning apparatus, and thus the cost of the entire apparatus can be reduced.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer drum 2 Application | coating apparatus 3 Inkjet recording head 4 Recording medium 5 Recording medium conveyance drum 6 Water | moisture-content removal acceleration | stimulation apparatus 7 Cleaning apparatus 8 Press roller 9 Intermediate conveyance drum 10 Torque limiters 11 and 12 Connecting gear 13 Drive motor 14 Reverse crown shape press Roller 15 Claw 16 Drum nip 17 Intermediate area

Claims (5)

A recording head for recording images;
A recording medium conveyance drum that conveys the recording medium while holding the leading end of the recording medium, a pressure roller that presses the recording medium against the recording medium conveyance drum, and a speed at which the pressure roller is slower than the rotation speed of the recording medium conveyance drum And a torque limiter connected between the pressing roller and the drive unit. The frictional force between the recording medium and the pressing roller is greater than the frictional force between the recording medium and the recording medium transport drum;
The recording apparatus according to claim 1. Having an intermediate transfer drum for transferring an image recorded by the recording head to the recording medium;
The recording apparatus according to claim 1, wherein: The pressing roller is disposed at a position for pressing the recording medium against an outer peripheral surface of the recording medium conveyance drum, and applies a force to the recording medium in a direction orthogonal to the conveyance direction of the recording medium;
The recording apparatus according to claim 1, wherein the recording apparatus is a recording apparatus.   The pressing roller has a central axis parallel to the rotation axis of the recording medium conveyance drum, and the outer diameter continuously increases from a relatively small diameter central portion toward both relatively large diameter ends. The recording apparatus according to claim 4, wherein the recording apparatus is a cylinder.

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