JP2006001180A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that an apparatus becomes large and the number of recorded sheets per unit time cannot be increased by a constant transfer speed because a perimetric length of a transfer belt is necessary to be not smaller than a length with a length of an opening added to a maximum recording medium length, and that an excess ink sucked by a maintenance unit scatters to the perimeter and contaminates a recording medium adhering to the transfer belt at the time of wiping the excess ink of a head by a wiper. <P>SOLUTION: A belt unit which can increase the number of recorded sheets per unit time without being limited by a paper size of the recording medium is set. The maintenance unit which prevents ink adhesion to a recording medium transfer means and can also maintain a line head by a saved space is thus constituted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a rotary maintenance mechanism that is used by switching a recording medium conveyance mechanism.

  In general, a head unit mounted on a carriage of an image forming apparatus, a so-called inkjet printer, ejects ink onto a recording medium conveyed in a recording medium conveyance direction perpendicular to the head while scanning and moving in the recording medium width direction. Image formation is performed.

  The head section is divided into a plurality of parts in the recording medium width direction, and has nozzle rows arranged alternately or obliquely in the recording medium conveyance direction. Some of the nozzles on the end side of these nozzle rows are arranged so as to overlap each other on the end side of the nozzle row adjacent to either the front or rear in the recording medium conveyance direction. Further, as a mechanism for transporting the recording medium, a recording medium transporting mechanism that is arranged to face the head portion and includes a belt unit that transports the recording medium while adsorbing the recording medium is proposed. The transport mechanism includes a platen that rotatably supports the belt, and is provided so that the maintenance unit moves as necessary to face the head nozzle surface. The maintenance unit is equipped with a wipe mechanism that abuts the head and sucks ink from each nozzle, or removes ink remaining on the head surface around the nozzle, and recovers nozzles that have failed due to clogging. A function is provided for this purpose.

In addition, an image recording apparatus using ink that is easily dried has a cap function for airtightly covering the nozzle surface during non-operation to prevent ink drying. Further, as a maintenance process, an operation for discharging the thickened ink in the nozzles is also performed before image recording or between image recording operations, and a function for sucking out the discharged ink is also provided.

  As a prior art, Patent Document 1 is known as an example of an apparatus using a line head mechanism. As shown in FIG. 13, the conveyance belt 99 of the belt conveyance device is partially provided with an opening. The opening is arranged in accordance with the position of the maintenance unit provided on the platen. A conveyance belt 99 arranged around the platen adsorbs the recording medium 98 to the conveyance belt 99 by static electricity or negative pressure adsorption by corona ions and conveys the recording medium 98 so as to pass under the head portion.

  The opening provided in the conveyance belt 99 is stopped using the position detection means of the conveyance belt 99 so that the head unit 97 and the maintenance unit face each other. At this position, the maintenance unit is moved upward, passes through the hole, crosses the recording medium conveyance path, and comes into contact with the head unit 97. During the recording operation, the recording medium 98 is transported so as to be placed on a portion of the transport belt 99 where there is no opening at a timing based on the transport speed. As an example of taking this timing, a registration roller or the like is used. The leading end of the recording medium 98 adsorbed by the belt unit is brought into contact with the nip portion of the resist roller that is stopped, and the position and timing of the conveying belt 99 are measured to carry the medium.

  As another conventional example, Patent Document 2 in which a maintenance unit is not incorporated in a belt platen and a maintenance unit is arranged outside the belt platen as shown in FIG. 14 is also known. When carrying out maintenance using the head unit 100, the head unit 100 moves greatly to a position outside the belt platen where the head unit 100 faces the maintenance unit 101 and performs a discharge recovery operation. In this configuration, the head unit 100 returns to the position facing the recording medium conveying unit again after recording after the recovery operation.

As another conventional example, as shown in FIG. 15, a maintenance unit 103 is arranged in the vicinity of the head 102, and the maintenance unit 103 is moved to a position facing the ink ejection surface of the head 102 as necessary. 3 is also known.
JP 2001-287377 A JP 2002-059559 A JP 2003-011377 A

  In the above-mentioned Patent Document 1, the recording medium conveying means needs to be fed in synchronization with the conveying belt avoiding the opening position when adsorbing the recording medium. The peripheral length of the conveyor belt needs to be at least the maximum recording medium length plus the length of the opening. Further, the conveying speed of the belt unit that conveys the recording medium was conveyed at a constant speed in accordance with the fastest frequency at which the head unit can eject ink onto the recording medium. However, it is problematic to reduce the size of the apparatus and increase the cost due to an increase in the number of components, which is to avoid the opening position and to synchronize and to provide a conveyor belt having a circumference longer than the maximum recording medium length. Furthermore, when recording on a recording medium at a constant conveying speed, the feeding timing is determined by the timing of one revolution of the belt, so the time required for the conveying belt to make one revolution of the belt unit is the same regardless of the paper size of the recording medium. Since the number of recordings does not change, the number of recordings per unit time cannot be increased. In addition, since the maintenance unit and the ink head are brought into contact with each other through the opening of the conveyor belt, the maintenance unit uses a timing when the ink head and the maintenance unit are separated from each other or when the excess ink remaining on the head portion is wiped off by the wiper. The excess ink sucked was scattered around. There is a problem that the ink scattered around the recording medium adheres to the conveyance belt and then stains the recording medium adsorbed on the conveyance belt.

  The maintenance method according to Patent Document 2 described above is a method in which the head portion is largely moved to the position of the maintenance unit located outside the belt platen. In this method, bending deformation or vibration is applied to the ink supply tube to the head portion, and vibration is also applied to the head portion itself, so that the meniscus of the discharge nozzle portion of the head is destroyed and non-discharge occurs again. There's a problem.

  In addition, the maintenance method according to Patent Document 3 includes a method in which a maintenance unit is arranged in the vicinity of the head and the maintenance unit is opposed to the ink discharge surface as necessary. This method has a problem that the interval between the color heads in the recording medium conveyance direction becomes long and is easily affected by the skew and conveyance unevenness of the recording medium, and color misregistration on the recording medium occurs.

  Therefore, the present invention is provided with a belt unit capable of increasing the number of recordings per unit time without being limited to the paper size of the recording medium, preventing ink adhesion to the recording medium conveying means, and maintaining the line head in a space-saving manner. An object of the present invention is to provide an image forming apparatus having a maintenance unit.

  In order to achieve the object of the present invention, a recording unit that discharges ink to a recording medium to record an image, a recording medium conveying unit that conveys a recording medium so as to face an ejection port of the recording unit that discharges ink, Maintenance means that protects the ejection port by contacting the ejection port other than when the recording unit is driven, or restores the function by ejecting the ink, the recording medium transport unit, and the maintenance unit are integrally arranged on the front and back sides. A movable unit that is rotatable and provided opposite to the recording means; and a switching means that performs switching control by rotating the operating unit and makes either the recording medium conveying means or the maintenance means face the discharge port of the recording means. An image forming apparatus is provided.

  The image forming apparatus of the present invention can increase the number of recording sheets per unit time without being limited to the paper size of the recording medium, prevent ink from adhering to the recording medium conveying means, and perform a maintenance process in a space-saving manner for the line head. It can be carried out.

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

  1 and 2 show a configuration example of a first embodiment according to an image forming apparatus having a switching mechanism of the present invention. In the following description, in the drawing, the conveyance direction of the recording medium is the X-axis direction or the sub-scanning direction, and the direction orthogonal to the conveyance direction is the Y-axis direction, the main scanning direction, or the width direction of the recording medium. The direction perpendicular to the X-axis and Y-axis directions is taken as the Z-axis direction or the vertical direction.

  In the present embodiment, a recording unit 2 that forms an image by ejecting ink to a recording medium from a plurality of ejection ports, a recording medium conveyance unit 5 that conveys a recording medium so as to face the ejection ports, and a recording medium conveyance unit 6 An adsorbing portion 6 that generates a negative pressure during conveyance and adsorbs the recording medium, and contacts the surface on which the ejection port is provided except when the recording unit 2 is driven, and protects the ejection port and ink. A maintenance unit 7 that restores the recording function by ejection, a suction unit 8 that is provided in the maintenance unit 7 and sucks ink ejected from the recording unit 2 by negative pressure, and a recording medium transport unit 5 and a maintenance unit 7 There is a movable unit that is integrated with the front and back, and by switching by rotation, one of the switching mechanism 4 for directly facing the discharge port of the recording unit 2 and either suction or suction are selected and negative A negative pressure source 9 for applying pressure, And a control unit 1 for controlling these component parts. The switching mechanism 4 includes a vertical rotation mechanism 3b and a motor unit 3a that switches and drives the vertical rotation mechanism 3b.

The line head mechanism according to this embodiment will be described with reference to FIGS.
The head unit 14 has an array 34 composed of a plurality of nozzle arrays that can handle a plurality of colors of ink, for example, black (K), cyan (C), magenta (M), yellow (Y), and the like. The nozzle rows for each color of the head unit 14 are arranged along the main scanning direction. In the present embodiment, the ejection port is disposed so as to eject ink in the gravitational direction (vertically downward). The plurality of head units 14 are alternately held on both side surfaces of the head base 15. The head base 15 also extends in the main scanning direction like the nozzle row, and is arranged so that the nozzles at the ends of the head units 14 arranged on both side surfaces partially overlap in the recording medium conveyance direction. At this time, the nozzle pitch is fixed to the head base 15 in consideration of equal pitches in the main scanning direction.

  In such an arrangement, the head units 14 are alternately arranged with their positions shifted in the recording medium conveyance direction, so that the ejection timing is individually adjusted. By this adjustment, the plurality of head units 14 can form one line in the main scanning direction, that is, the width direction of the recording medium 11, and are driven in the same manner as a conventional one line head. The belt unit 33 is provided with an endless belt 21 that is stretched between the driven roller 18 and the driving roller 32, and conveys the recording medium 11 as it rotates. Therefore, the belt unit 33 is not limited by the length of the recording medium 11, and may have a minimum length (transport direction) sufficient to support and transport the recording medium 11 in the area of the platen portion, thereby saving space. Can be made.

With reference to FIG. 2 and FIG. 4, the configuration of the belt unit 33 serving as the recording medium conveyance unit 5 and its peripheral part will be described in detail.
The belt unit 33 provided to face the head unit 14 is sandwiched and supported by a pair of rotating frames 19 from both sides in the transport direction. A large number of small-diameter holes (not shown) are opened on the surface of the platen portion facing the head unit 14. The belt unit 33 in the platen portion includes an endless belt 21 that is stretched between the driven roller 18 and the driving roller 32. A number of small diameters are opened on the endless belt 21 in the belt unit 33. A chamber 22 for generating negative pressure is provided between the driven roller 18 and the driving roller 32 in the endless belt. The chamber 22 has a large number of small diameters only on the surface facing the head unit 14. The positioning portion 35 is formed on the belt unit 33 side so as to protrude from the rotary frame 19 so that the interval between the nozzle surface for ejecting ink of the head unit 14 and the recording medium 11 becomes a predetermined specified value. Is provided.

  Further, around the head unit 14 disposed opposite to the belt unit 33, a registration roller pair 10 that corrects an oblique displacement of the recording medium 11, a guide pair 12 for conveying the recording medium 11, a backup roller 13, and A guide 16 for guiding the recording medium 11 to the paper discharge roller pair 17 is provided in the vicinity.

The configuration of the maintenance unit 7 will be described in detail with reference to FIG.
The maintenance unit 31 is provided with a plurality of caps 27 so as to face the head unit 14. The cap 27 is biased toward the head unit 14 by a spring 28, and the spring 28 bends so that the cap 27 can be in close contact with the head unit 14 only when facing the ink head portion. The cap 27 is formed of an elastic member such as resin or rubber, and is provided with a suction hole (not shown) communicating with the negative pressure source 9. The cap 27 is provided inside the ink pan 26. The ink pan 26 has a box shape and is provided therebetween so as to prevent ink overflowing from the cap 27 from flowing down onto the belt unit 33. Further, an ink absorber 25 is affixed to the ink pan 26 to prevent spilled ink from adhering to the belt unit 33 due to the rotation of the rotating frame 19.
As shown in FIG. 4, a maintenance unit 31 and a belt unit 33 are provided on both the front and back surfaces of the rotating frame 19 and are integrally configured. In FIG. 4, the belt unit 33 faces the head unit 14, but the mechanism allows the head unit 14 and the maintenance unit 31 to face each other when the rotating frame 19 rotates 180 degrees.

The switching mechanism of the rotating frame 19 will be described with reference to FIGS.
FIG. 5 is a view of a cross section of one side of the rotating frame 19 that is paired on the left and right. The rotating frame 19 includes a belt unit 33 and a maintenance unit 31 as shown in FIG. 4, and both end portions of the rotating frame 19 have bent portions 20 and 24. The rotating frame 19 is rotatably held by a rotating shaft 40 via a bearing 53, and the rotating shaft 40 has a gear 36 fixed to the outside of the rotating frame 19.

  A motor 39 for applying a rotational driving force is fixed to the rotary frame 19, and a gear 38 is attached to the motor shaft. The gear 38 meshes with a gear 36 provided outside the rotating frame 19, and the rotating shaft 40 is interlocked with the rotation of the motor 39. In the image forming apparatus main body, a pair of brackets 30 are provided below the head unit 14. A pair of moving frames 29 are provided on the inner side with the rotating frame 19 in between, and are fitted via a rotating shaft 40 and a bearing 41. A gear 37 is fixed to the end of the rotating shaft 40 and meshes with the rack 42.

FIG. 6 is a view showing the configuration of the rotating frame 19 as viewed from the side.
The pair of brackets 30 shown in FIG. 6 are integrally formed by welding a long hole 44 opened in the longitudinal direction and a rack 42 in parallel therewith. The rotating shaft 40 and the shaft 43 are provided so as to penetrate the moving frame 29 in the direction of gravity. The rotating shaft 40 and the guide shaft 43 are engaged with elongated holes 44 provided in the brackets 30 on both sides. The guide shaft 43 functions as a stopper guide when the moving frame 29 descends to the lowest end of the long hole 44 in the bracket 30. Bending portions 20 and 24 provided at both ends of the rotary frame 19 are provided with holes 20a and 24a as shown in FIG. The holes 20a and 24a are opened so as to have some play in the rotation direction. The moving frame 29 rises, the cap 27 comes into contact with the head unit 14, the spring 28 is bent, and the cap 27 and the head unit 14 come into close contact with each other, so that the cap 27 fits in the head unit 14 within the range of play. Designed to be As shown in FIGS. 6 and 9, a solenoid 23 is fixed to the moving frame 29, and the plunger 23 a engages holes 20 a and 24 a provided in the rotating frame bending portions 20 and 24. The plunger 23a functions as a stopper that is allowed to rotate when the plunger 23a is detached and is prevented from rotating when the plunger 23a is engaged.

  With reference to FIG. 2 and FIG. 4, a conveyance / suction method by the recording medium 11 in the platen part and a maintenance / suction method of the head unit 14 will be described.

  First, the recording medium 11 is taken out one by one by a recording medium supply mechanism (not shown), abuts against the registration roller pair 10, and after the oblique displacement is corrected, passes through the guide pair 12, and passes through the endless belt 21 and the backup. It is conveyed to the nip portion composed of the roller 13. When the recording medium 11 is conveyed, the endless belt 21 passes through a large number of small diameters provided on the surface of the chamber 22 facing the head unit 14 and the endless belt 21 by negative pressure suction of the chamber 22 provided in the belt unit 33. Is sucked by negative pressure and conveyed.

  At this time, the distance between the recording medium 11 and the head unit 14 is kept constant by the positioning unit 35. The interval between the head unit 14 and the recording medium 11 is generally 1 mm to 3 mm, and the landing accuracy of the ejected ink improves as the interval decreases. The adsorbed recording medium 11 is transported to the platen portion below the head unit 14 and then ink is ejected from each nozzle to form an image. After that, it is guided by the guide pair 16, nipped by the paper discharge roller pair 17 and discharged outside the apparatus.

  In the maintenance / suction method of the head unit 14, the cap 27 protects the nozzle surface from dust and drying while in contact with the head unit 14. Further, by applying a negative pressure to the suction hole in a close contact state, the ink is sucked out from the nozzles of the head unit 14 so that the nozzles that can no longer eject ink during the recording or before or after the start of the recording are recovered. To work. The recovery function removes dust and bubbles clogged in the nozzle by setting the inside of the cap 27 to a negative pressure and sucking out the ink inside the head from the nozzle. A new meniscus is formed by the ink drawn to the tip of the nozzle and can be ejected again.

7 and 8 are diagrams illustrating a method of switching the rotating frame 19 from the maintenance unit 31 to the belt unit 33. FIG.
FIG. 7 shows a state in which the cap 27 is in close contact with the nozzle surface of the head unit 14 and protects the nozzle surface from drying, dust and the like. At this time, in the rotating mechanism, when the motor 38 rotates rightward (as viewed from the gear 39 side) while the plunger 23a of the solenoid 23 is engaged with the rotating frame 19, the gear 36 is connected via the gear 36. The rotary shaft 40 provided in front of is rotated, and the gear 37 provided in front of the gear 36 is driven to rotate. Thereafter, as shown in FIG. 5, the rack 42 and the gear 37 are engaged with each other, so that the moving frame 29 shown in FIG. 6 starts to descend. As a result, the cap 27 is detached from the head unit 14. The descent stops when the bearing portion of the guide shaft 43 reaches the lowermost end of the long hole 44 of the bracket 30. At this position, the solenoid 23 is driven to disengage the plunger 23a from the rotating frame bending portion 20a, and the motor 39 is further rotated to the right. Since the gear 37 and the rack 42 mesh with each other and the gear 37 cannot rotate, the gear 36 provided on the same rotation shaft 40 cannot rotate. Therefore, the gear 38 becomes a planetary gear with respect to the gear 36 and rotates around it. As a result, the rotating frame 19 starts to rotate as shown in FIG. When the belt unit 33 comes to a position facing the head unit 14, the drive of the solenoid 23 is stopped. The plunger 23a is engaged with the bending part 24, and the rotation frame 19 stops rotating. In this state, when the motor 39 is rotated counterclockwise, the rotating shaft 40 is rotated in the opposite direction through the meshed gears 38 and 36, and the moving frame 29 starts to rise due to the meshing of the gear 37 and the rack 42. . The highest point is detected by a sensor (not shown), and the drive of the motor 39 is stopped.

At that time, the belt unit 33 is opposed to the head unit 1 as shown in FIG.
Conversely, switching from the belt unit 33 to the maintenance unit 31 similarly causes the motor 39 to rotate clockwise when viewed from the gear 38 side, and the moving frame 29 rotates to move to the lowest point. By operating the solenoid 33 at that position, the plunger 23a is detached from the rotary frame 19, and the motor 39 rotates in the reverse direction. By setting the weight of all the members held by the moving frame 29 to a certain level or more, the moving frame 29 does not rise by the driving force of the motor 39, and the gear 38 rotates as a planetary gear around the gear 36. The rotary frame 19 rotates.

  When the maintenance unit 31 comes to a position facing the head unit 14, the solenoid 23 is turned off and the plunger 23 a is engaged with the rotary frame 19 to stop the rotation.

  When the rotation is stopped, the driving force of the motor 39 becomes a force for rotating the gear 36 and the gear 37, and the moving frame 29 is raised. The installation of the speed reduction mechanism between the motor 39 and the gear 38 serves to prevent the moving frame 29 from dropping due to its own weight even when the motor 39 is turned off. The switching configuration of the belt unit 33 and the maintenance unit 31 at a position apart from the position of the head unit 14 enables the movable part to switch without interfering with the surroundings.

  As shown in FIG. 2, the switching mechanism in the present embodiment is such that the suction unit 6 of the recording medium transport unit 5 and the suction unit 8 of the maintenance unit 7 are integrated with each other with respect to the recording unit 2. At the time of image formation, the recording medium 11 is attracted to the recording medium transport unit 5 and proper recording is performed while maintaining a uniform interval. In the recording unit 2, the suction unit 8 provided in the maintenance unit 7 is in close contact with the surface of the recording unit 2 on which the ejection port is provided, and sucks ink by negative pressure. The cap 27 is in close contact with the recording unit 2 and has a function of preventing dust and drying on the recording unit 2. By using the switching mechanism 4, any one of the recording unit 2, the recording medium transport unit 5, and the maintenance unit 7 is in opposition. From the above, this apparatus is a rotational movement mechanism using the motor 39 as a drive source, and the maintenance unit 31 and the belt unit 33 which are moving parts may be connected only by the power supply wiring. As a result, it is possible to realize a movable mechanism in an inexpensive and small space.

  Further, in the present embodiment, it has been described that the rotation stop of the rotation frame is performed by the engagement of the plunger 23a and the rotation frame 19, but a rotation position sensor may be separately provided and the rotation position may be stopped by a detected signal. .

  In addition to the plunger 23a, a separate stopper member may be provided to regulate the rotation angle. When the transporting JAM of the recording medium 11 occurs in the vicinity of the recording unit using a mechanism that moves the movable unit to a position separated from the head unit 14 using the motor 39 as a driving source, the belt unit 33 is moved to the head. It is also possible for the operator to perform JAM processing by separating from the unit 14.

FIG. 9 is a diagram showing a configuration in which the belt unit 33 is raised from the maintenance unit 31 so as to face the head unit 14 by the rotation mechanism.
At the time of switching from the maintenance unit 31 to the belt unit 33, in order to realize image formation without ink unevenness on the recording medium 11, the distance between the belt unit 33 and the head unit 14 is made uniform and correctly opposed. There is a need. For this reason, the rotating frame 19 has the positioning portion 35 in contact with a portion that does not participate in recording of the head unit 14 itself within a range of rotation angle, a part of the head base 15, or a part of the fixed frame that holds the head base 15. To be set.

  FIG. 9 shows a state in which the positioning portion 35 is in contact with a portion of the head unit 14 that does not participate in image formation, and the nozzle surface and the endless belt 21 are set in parallel with a predetermined interval (about 1 mm to 3 mm). Yes.

  With the above configuration, as shown in FIG. 9, when the belt unit 33 is set on the side facing the head unit 14, the belt unit 33 is lifted so as to be close to the head unit 14 and the head of the positioning unit 35. By the contact with the unit 14, the interval is appropriately positioned.

  In the present embodiment, a configuration example is provided in which the plunger 23a and the positioning hole of the rotating frame 19 have a play to operate the rotating frame 19 side. However, the present invention is not limited to this, and the rotation of the rotary frame 19 is positioned without play, and play is provided on the side of the head holding member such as the head base 15 to which the head unit 14 is attached with respect to the rotary frame 19. Is also possible. Or you may use together the play of rotation of the rotation frame 19, and the play of the head holding member side which has the head unit 14 together.

  FIG. 10 is a diagram showing a configuration example of a negative pressure switching mechanism of a negative pressure source that switches between the cap 27 and the chamber 22 of the negative pressure source belt unit 33 by one negative pressure source and generates a negative pressure in any one of them.

  In this negative pressure switching mechanism, the negative pressure source generated in the cap 27 and the negative pressure source generated in the chamber 22 of the belt unit 33 are not used at the same time. Can be used. The negative pressure source 9 is provided at a position lower than the rotation shaft, and one tube 46 connected to the negative pressure source 9 is connected to a dial 47 (described later) with which the rotation shaft 40 is fitted. Since the dial 47 is provided with two inlets, the tube 46 is branched into two upper and lower forks on the way and connected to each other.

  The negative pressure source 9 is installed at a position lower than the rotary shaft 40, for example, even when the maintenance unit 31 faces the head unit 14 and the belt unit 33 is set on the lower side than the maintenance unit 31. The branch point is at a position lower than the recording medium conveyance surface of the endless belt 21. Accordingly, it is possible to prevent the ink sucked from the maintenance unit 31 from flowing back to the belt unit 33 side. The tube 46 branched into two forks is connected to two inlets provided in the switching dial 47. The switching dial 47 is composed of two disks that are airtight and rotatably connected. One of these disks is fixed to the rotating frame 19 side, and the other is fixed to a moving frame 29 (not shown). The dial 47 is fitted coaxially with the rotary shaft 40. Both disks can be rotated 180 degrees. With this rotation, the suction path to the chamber 22 of the belt unit 33 and the cap 27 of the maintenance unit 31 is switched. The tube 46 connected to the negative pressure source 9 is supplied to an introduction port formed on the disk side fixed to the moving frame 29.

  In the dial 47 in which two tubes are connected to each inlet, an intake system is constructed using members such as a tube (not shown) up to the chamber 22 of the belt unit 33 and the cap 27 of the maintenance unit 31.

  The switching of the intake system is linked to the switching operation of the maintenance unit 31 and the belt unit 33 accompanying the rotation of the rotary frame 19. As a result, the dial 47 rotates, and the suction path from the negative pressure source 9 is switched. In this configuration, the unit on the side facing the head unit and the negative pressure source 9 are always connected and inhaled.

  In this embodiment, FIG. 10 is used, and the connection switching between the negative pressure source 9 and the maintenance unit 31 or the belt unit 33 uses the dial 9. However, the present invention is not limited to this, and it may be controlled to connect any unit and a negative pressure source using the electromagnetic valve 51 as shown in FIG.

  FIG. 11 shows a modification of the first embodiment described above. In this modification, a solenoid valve 51 is used instead of the dial 47. Constituent parts that are the same as those in the first embodiment described above are given the same reference numerals, and detailed descriptions thereof are omitted.

  This modification includes a negative pressure source 9, a tube 46, an electromagnetic valve 51, a belt unit 33, a chamber 22, a maintenance unit 31 and a cap 27. The two solenoid valves 51 perform alternate opening / closing control. In the alternate open / close control, the negative pressure of the negative pressure source 9 can be applied to either the chamber 22 or the cap 27.

  FIG. 12 is a view showing the height positional relationship of the branch portion of the tube 46. It is desirable that the branch portion 46 a of the tube 46 be provided below the chamber 22. It is desirable that at least the tube after branching at the branching portion 46a is arranged at a higher position than the portion before branching. Ink sucked from the cap 27 is prevented from flowing into the chamber 22 side by the branching portion 46a installed below the chamber 22.

  On the contrary, when the maintenance unit 31 faces downward, the waste liquid inside the cap 27 may drip. Therefore, the ink absorber 25 is provided directly under the maintenance unit 31 to prevent the inside of the apparatus from being contaminated with ink.

  In the present invention, the belt unit 33 having a suction belt has been described as an example of means for conveying the recording medium 11 facing the head unit 14. However, the present invention is not limited thereto, and only suction suction means that does not have a belt may be used.

  In the present embodiment, the cap 27 that covers the entire head unit 14 as shown in FIG. 7 has been described as an example. However, the present invention is not limited to this, and a cap that covers one or a plurality of nozzle rows may be used.

  According to the present invention, the switching mechanism is a movable unit in which a belt unit provided with a suction portion and a maintenance unit provided with a suction portion are combined in a front-back relationship. The suction unit of the belt unit and the suction unit of the maintenance unit have a common power source, and the drive source that rotates the movable unit and the rotary frame move up and down, and the drive source is single. Since the rotating frame is rotated 180 degrees by a single drive source and the movable unit facing the head unit is rotated, there is no need to move the head unit. At the time of image formation, the belt unit opposed to the head unit adsorbs the recording medium 11 conveyed by negative pressure adsorption by the chamber to the belt unit, and the positioning unit keeps the distance between the head unit and the recording medium constant so that proper recording is performed. I do. At the time of maintenance, the cap provided in the maintenance unit 7 is in close contact with the surface of the ink head provided at the ejection port for ejecting ink, and sucks ink left in the head by negative pressure suction. As it is, the cap 27 also has a function of being in close contact with the recording unit 2 and preventing dust and drying on the recording unit 2. By providing an ink absorber at the boundary between the belt unit and the maintenance unit, there is a function of preventing ink sucked through the cap from leaking to the recording medium conveying means when switching the surface facing the ink head. By using the switching mechanism 4, one of the recording unit 2, the recording medium transport unit 5, and the maintenance unit 7 faces each other, and only the facing unit is supplied with power. As described above, this apparatus is a rotational movement mechanism that prevents the ink from adhering to the recording medium through the recording medium conveying means, can maintain the line head mechanism in a small space, and uses the motor 39 as a single drive source. The suction unit provided and the suction unit provided in the belt unit use a single power source, thereby realizing an inexpensive maintenance mechanism.

1 is a block diagram of an image forming apparatus having a negative pressure switching mechanism according to a first embodiment of the present invention. 1 is a diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. It is a figure which shows the line head mechanism applied to the image forming apparatus of 1st Embodiment. FIG. 3 is a diagram illustrating a recording medium conveyance method in the image forming apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a cross section on one side of a rotating frame that is a left-right pair in the image forming apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a side surface of a rotating frame in the image forming apparatus of the first embodiment. FIG. 3 is a diagram illustrating adhesion between a head unit and a maintenance unit in the image forming apparatus according to the first embodiment. FIG. 3 is a diagram illustrating rotation start of a rotating frame in the image forming apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a configuration in which a belt unit ascends facing a head unit by a rotation mechanism in the image forming apparatus of the first embodiment. FIG. 3 is a diagram illustrating switching with a negative pressure source in the image forming apparatus according to the first embodiment. FIG. 3 is a schematic diagram when an electromagnetic valve is used instead of a dial in the image forming apparatus according to the first embodiment. It is a figure which shows the height relationship of the branch position of the pipe connected to a chamber and a cap from a negative pressure source. It is a figure which shows the structural example of the conventional recording-medium conveyance method. It is a figure which shows the structural example of the conventional maintenance unit. It is a figure which shows the structural example of the conventional maintenance unit.

Explanation of symbols

  1: control unit, 2: recording unit, 3: motor unit, 4: vertical rotation transfer mechanism, 5: recording medium transport unit, 6: suction unit, 7: maintenance unit, 8: suction unit, 9: negative pressure source, 10: registration roller pair, 11: recording medium, 12: guide pair, 13: backup roller, 14: head unit, 15: head base, 16: guide pair, 17: paper discharge roller pair, 18: driven roller, 19: Rotating frame, 20: rotating frame bending part, 21: endless belt, 22: chamber, 23: solenoid, 24: rotating frame bending part, 25: ink absorber, 26: ink pan, 27: cap, 28: spring, 29 : Moving frame, 30: Bracket, 31: Maintenance unit, 32: Drive roller, 33: Belt unit, 34: Array, 35: Abutting part, 36: Gear, 37 Gear: 38: Gear, 39: Gear, 40: Rotating shaft, 41: Bearing, 42: Rack, 43: Shaft, 44: Long hole, 45: Joint part, 46: Branch position, 47: Dial, 48: Case, 49: Joint part, 51: Solenoid valve, 52: Platen unit, 53: Bearing

Claims (11)

A recording means for recording an image by discharging ink to a recording medium;
A recording medium transporting means for transporting the recording medium so as to face an ejection port for ejecting ink of the recording means, and abutting the ejection port to protect the ejection port except when the recording unit is driven, or Maintenance means for recovering the function by discharging ink;
The recording medium conveying means and the maintenance means are arranged integrally on the front and back sides, and a movable unit that is rotatable and provided facing the recording means;
A switching unit that performs switching control by rotation of the movable unit, and makes one of the recording medium conveying unit and the maintenance unit face an ejection port of the recording unit;
An image forming apparatus comprising: The switching means is a moving means for moving the recording medium conveying means or the maintenance means relative to the recording means between a close position and a separate position;
A rotation selection unit that selects one of the recording medium conveyance unit and the maintenance unit by rotation at a position separated from the recording unit and opposes the discharge port;
2. The image forming apparatus according to claim 1, further comprising: Positioning in which a contact portion is arranged in a part of the movable unit combining the recording medium conveying unit and the maintenance unit and the movable unit, and the movable unit provided on the opposing surface of the recording unit is loosely fitted when switching. Having means,
2. The image forming apparatus according to claim 1, wherein the contact portion is positioned in contact with the recording unit at a position where the movable unit is close to the recording unit. In addition, the ink holding means disposed between the recording medium conveying means and the maintenance means,
2. The image forming apparatus according to claim 1, wherein ink dripping from the maintenance unit to the recording medium conveying unit is absorbed.   The image forming apparatus according to claim 1, wherein the ink holding unit is arranged below the gravitational direction of the movable unit including the recording medium conveying unit and the maintenance unit.   The recording medium conveying means and the maintenance unit have a common negative pressure source, and one path from the negative pressure source branches into two paths leading to the conveying unit and the maintenance unit, and the switching is performed. 2. The image forming apparatus according to claim 1, wherein the path of the negative pressure source is connected to the side switched by the means. The recording medium conveying means includes an adsorption means for adsorbing the conveyed recording medium on a conveying belt;
The maintenance means includes a suction means for sucking ink from the recording means when the cap member covers the head unit;
The image forming apparatus according to claim 1, further comprising: A head portion which is a recording means for recording an image by discharging ink to a recording medium;
A recording medium transport mechanism for transporting the recording medium so as to face an ejection port for ejecting ink of the recording means;
A maintenance mechanism that contacts the discharge port other than when the recording unit is driven and protects the head unit from dust and drying, or recovers the recording function by discharging ink;
A movable unit in which the recording medium conveying means and the maintenance means are disposed integrally on the front and back;
A cap member that is detachably provided in the maintenance mechanism and protects the head portion from dust and drying by contact;
A pair of rotating frames that rotatably support the movable unit on both sides from the recording medium conveyance width direction and hold the movable unit at a position facing the head unit;
A drive mechanism for moving the movable unit relative to the rotating frame;
A support shaft that rotatably supports the movable unit on the frame;
A rotation mechanism for rotating the movable unit about the support shaft;
A reciprocating mechanism for separating the support shaft and the movable unit from the head unit by a desired distance;
An image forming apparatus comprising:   9. The image forming apparatus according to claim 8, wherein the rotating mechanism and the reciprocating mechanism are driven by a driving source including a single motor.   The image according to claim 8, wherein the head unit is an ink jet head in which a plurality of nozzle rows that can correspond to a plurality of colors are arranged in a direction orthogonal to the recording medium conveyance width direction over a recordable width. Forming equipment.   The image forming apparatus according to claim 8, wherein the recording unit is an ink jet head in which a plurality of nozzles are arranged over a recordable width in a direction orthogonal to the recording medium conveyance width direction.

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