JP2009067569A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device eliminating the need of adjusting both of a carrying mechanism and an ink head group, in a carrying direction adjusting method when a gap is generated between a carrying direction of an image recording medium by the carrying mechanism and a carrying direction of an image recording medium by a carrying roller due to the unevenness of component accuracy of the carrying roller or mounting accuracy. <P>SOLUTION: A head frame holding an ink head; and a driving roller 15a directly positioning the carrying mechanism carrying sheets at a position opposite to the ink head, and correcting skewing or adjusting carrying timing are held by an arm 43a extended from the head frame. By an adjusting screw, a driving bearing 44a is moved in a ring guide hole 45 formed in the arm 43a to move the driving roller 15a in a carrying direction of the sheets. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an improvement in an image forming apparatus that adjusts a conveyance roller in a conveyance direction of a recording medium by a conveyance roller.

  The image forming apparatus ejects ink liquids of each color from a plurality of ink head groups, that is, ink liquids of each color of black (k), cyan (c), magenta (m), and yellow (y) to record an image. Some form an image on a medium. In such an image forming apparatus, a transport mechanism for transporting an image forming medium is provided, and black (k), cyan (c), magenta (m), and yellow (y) ink liquids are provided above the transport mechanism. It has a recording unit that fixes and arranges the ejected ink head group at a predetermined interval along the conveyance direction of the image forming medium.

  Note that the transport mechanism adopts a configuration in which, for example, an endless belt is supported by applying tension with a plurality of rollers, the rollers are driven to rotate, and the belt is moved. On the carry-in side (upstream side) of this conveyance mechanism, a pair of the image formation medium for introducing the image formation medium into the belt platen by regulating and correcting the rotation of the conveyance direction (skew) of the image formation medium or rotating the stationary mechanism. A conveyance roller is provided.

  Here, in order to realize high-accuracy image quality, the recording direction of the image recording medium regulated by the conveyance roller (correcting skew) and the image recording by the conveyance mechanism at a position facing the ink head group. Printing accuracy is ensured because the media transport directions match and the nozzle rows of the ink head groups held in the recording unit are provided in parallel to the direction perpendicular to the image recording media transport direction. Is done.

  That is, if the positional relationship described above is not stable, in the superposition of the four colors formed on the image recording medium, a positional shift occurs between the pixels of each color, resulting in a color shift in the formed image, and a high accuracy. Good printing cannot be secured.

  In order to solve such a problem, the following Patent Document 1 discloses a recording unit that holds an ink head group, an extension arm that is provided integrally with the recording unit, and a rotary arm that is rotatably held by the extension arm. Image forming apparatus having a regulating unit that is provided in the conveyance roller, a conveyance mechanism at a position facing the recording unit, and a recording unit and a conveyance mechanism, and regulates a positional relationship between the recording unit and the conveyance mechanism by mutual contact Has been proposed.

With the above configuration, since the recording unit and the transport mechanism are directly positioned by the regulating unit during image formation on the image recording medium, the positional relationship between the recording unit and the transport mechanism is always kept constant. It is possible. Further, since the conveyance roller is rotatably held by an arm extending from the recording unit, the positional accuracy between the recording unit and the conveyance roller can be kept constant.
JP 2006-212927 A

  However, in the apparatus described in Patent Document 1, if a deviation occurs between the conveyance roller and the recording unit due to variations in the accuracy of parts of the conveyance roller itself, attachment errors, or the like, an image recording medium by the conveyance roller is used. Discrepancies also occur in the transport direction of the image recording medium and the transport direction of the image recording medium by the transport mechanism whose positioning is regulated by the recording unit. As a result, the conveyance direction of the image recording medium must be adjusted by the conveyance mechanism.

  Here, if the conveyance direction of the image recording medium is adjusted by the conveyance mechanism with respect to the conveyance roller, a deviation occurs between the nozzle array of the ink head group and the conveyance direction of the image recording medium by the conveyance mechanism. Good printing cannot be ensured, and eventually the position of the ink head group needs to be adjusted.

  Therefore, the present invention has been made in view of the above circumstances, and the object thereof is not to adjust both the transport mechanism and the ink head group due to variations in the accuracy of parts and mounting accuracy of the transport roller. An image forming apparatus is provided.

  In order to solve the above problems, an image forming apparatus of the present invention includes a transport mechanism that transports a recording medium, and at least a width of the recording medium in a direction orthogonal to the transport direction of the recording medium transported by the transport mechanism. A line head arranged over the head, a head frame that holds the line head substantially in parallel at a predetermined interval, and is spaced apart from the transport mechanism at a position facing the transport mechanism; and the head frame and the transport mechanism A restricting portion that regulates the mutual positional relationship between the head frame and the transport mechanism, and an arm that is provided integrally with the head frame and that extends to the recording medium introduction side in the transport mechanism; A registration roller that is held by an arm and restricts the conveyance posture when the recording medium is introduced into the conveyance mechanism and introduces the recording medium into the conveyance mechanism, and is introduced by the registration roller And having a an adjustment mechanism for adjusting the registration rollers so that the conveying direction of the recording medium conveyed by the conveying direction and the conveying mechanism of the recording medium match.

  Further, the image forming apparatus of the present invention is disposed over the width of the recording medium at least in the direction perpendicular to the conveying direction of the recording medium conveyed by the conveying mechanism and the conveying mechanism. A line head, a head frame that holds the line head substantially in parallel at a predetermined interval, is disposed at a position facing the transport mechanism and is separated from the transport mechanism, and a head frame provided on the recording medium introduction side of the head frame And at least two restricting members that restrict the mutual positional relationship between the head frame and the transport mechanism, and an arm that is movably provided on the head frame and that extends to the recording medium introduction side of the transport mechanism; A registration roller that holds the recording medium and restricts the conveying posture when the recording medium is introduced into the conveying mechanism and introduces the recording medium into the conveying mechanism. Both are positioned by two restricting members, and rotated around one of the at least two restricting members as a fulcrum, so that the recording medium transported by the registration roller is transported by the transport mechanism. The registration roller is adjusted so that the conveyance direction of the medium matches.

  According to the present invention, it is possible to provide an image forming apparatus that does not require adjustment of both the transport mechanism and the ink head group due to variations in component accuracy and mounting accuracy of the transport roller.

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

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a side view schematically showing an image forming apparatus according to the first embodiment of the present invention, and FIG. 2 is a perspective view schematically showing the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a perspective view of a head frame as a recording unit and a registration roller unit as a conveyance roller of the image forming apparatus according to the first embodiment of the present invention as viewed from below, and FIG. FIG. 5 is a perspective view showing a relationship between a belt platen serving as a transport mechanism, a head frame, and a registration roller pair during image formation of the image forming apparatus according to the first embodiment. FIG. 5 is a diagram illustrating the first embodiment of the present invention. FIG. 6 is a detailed view showing the holding and adjusting unit of the registration roller pair of the image forming apparatus, and FIG. 6 shows the holding unit and the adjusting unit of the registration roller pair of the image forming apparatus according to the first embodiment of the present invention from the back side. FIG. 7 is a detailed view showing the first embodiment of the present invention. FIG. 8 is a detailed view showing a holding unit and a driving unit of a registration roller pair of the image forming apparatus in FIG. 8, and FIG. 8 is an adjustment direction of the registration roller pair as viewed from above the image forming apparatus in the first embodiment of the present invention. It is explanatory drawing showing. However, FIG. 8 exaggerates the adjustment angle for explanatory purposes.

  In FIG. 1, the image forming apparatus 10 according to the first embodiment has a paper feed tray 12 removably attached to a side surface (left side surface in FIG. 1) of the apparatus main body 11. In the paper feed tray 12, sheets 13 as a large number of image recording media are placed and accommodated. A pickup roller 14 is provided at the paper feed end of the paper feed tray 12 (the right end in FIG. 1). The pickup roller 14 picks up the sheets 13 stored in the paper feed tray 12 one by one and feeds them into the apparatus main body 11.

  A registration roller pair 15 as a transport roller is disposed on the transport path extension line of the sheet 13 fed into the apparatus main body 11 from the pickup roller 14. The registration roller pair 15 includes a driving roller 15a on the driving side and a driven roller 15b that follows the rotation of the driving roller 15a. The driven roller 15b is biased by the driving roller 15a. ing.

  From the upstream side to the downstream side in the sheet (sheet) conveyance direction of the registration roller pair 15, the upper registration guide 16a and the lower registration guide 16b have a distance suitable for the sheet 13 to pass between them. Open and arranged. As a result, the sheet 13 is fed from the pickup roller 14 to the registration roller pair 15 in a state where the sheet 13 is stable in the vertical direction. Then, the transported posture in which the skew has occurred is forcibly corrected to the correct posture by the registration roller pair 15.

  The sheet 13 whose transported posture is corrected is transported to a belt platen 18 as a transport mechanism at a predetermined timing. The belt platen 18 includes a belt 19, a belt driving roller 20, a belt driven roller 21, a tension roller 22, a platen 23, and suction fans 24a and 24b, and is attached to platen frames 26a and 26b, respectively. Together, these form a belt platen 18. The belt platen 18 is loaded on an elevating mechanism 27, and the elevating mechanism 27 moves up and down (moves in the Z-axis direction in the figure) to make the interval with the head frame 30 described later variable.

  The belt driving roller 20 and the belt driven roller 21 are disposed on the paper discharge side and the paper supply side of the platen frames 26a and 26b, respectively. The tension roller 22 is disposed inside the belt at the approximate center of the lower circulation portion of the belt 19.

  The belt 19 is configured in an endless belt shape, and an infinite number of holes are provided on the surface thereof. The belt 19 is stretched between the belt driving roller 20 and the belt driven roller 21. Further, the tension roller 22 pushes the lower circulation portion of the belt 19 outward and urges the belt 19 to move the belt 19 to the above three. It is stretched between the rollers. In this state, the belt 19 forms a sheet conveying surface in the upper circulation portion between the belt driving roller 20 and the belt driven roller 21.

  The platen 23 is a plate-like member in which an infinite number of holes are formed, and is disposed along the inner side of the belt on the sheet conveying surface of the belt 19. Under the platen 23, suction fans 24a and 24b are arranged. The platen 23 is processed with a predetermined flatness so that the sheet 13 does not meander, and is fixed to the platen frames 26a and 26b while maintaining the flatness.

  Both ends of the belt driving roller 20 and the belt driven roller 21 are rotatably held so as to be parallel depending on the processing accuracy of the platen frames 26a and 26b. The tension roller 22 is held by the platen frames 26a and 26b in a state in which tension is applied to the belt 19 and the shift of the belt 19 (biased in either the right or left direction perpendicular to the moving direction) can be adjusted.

  A head frame 30 is disposed above the belt platen 18. The head frame 30 positions and holds the ink heads 31k, 31c, 31m, and 31y. The ink heads 31k, 31c, 31m, and 31y form a line head by one or a plurality of ink heads. In this embodiment, a plurality of ink heads are arranged in a staggered pattern to form a single color line head. For example, the ink heads 31k and 31c are provided for each color of black, cyan, magenta, and yellow. , 31m, 31y.

  The ink heads 31k, 31c, 31m, and 31y are equal to or greater than the width of the sheet 13 in the direction orthogonal to the conveying direction of the belt 19 and in parallel with the respective ink heads 31k, 31c, 31m, and 31y. Thus extending in the Y-axis direction and held by the head frame 30 at a predetermined interval.

  In addition, on the sheet conveyance path downstream from the belt 19, image recording is performed on the right side surface of the apparatus main body 11 in FIG. 1, and the sheet is discharged for discharging the sheet 13 conveyed from the belt 19. A roller pair 33 and a paper discharge tray 34 on which the sheet 13 discharged from the paper discharge roller pair 33 is placed and stored are provided.

  Next, a configuration for positioning the head frame 30 and the belt platen 18 will be described.

  Positioning pins 37a, 37b, 37c, and 37d as restricting members are attached to the four corners of the lower surface of the head frame 30 in a suspended state. The two positioning pins 37a and 37b on the upstream side of the sheet 13 have a stepped shape, and the two positioning pins 37c and 37d on the downstream side of the sheet 13 have a stepped shape. I am doing.

  On the other hand, positioning holes 41 a and 41 b are formed in the platen 23 of the belt platen 18. Then, the positions of the head frame 30 and the platen 23 in the X and Y axis directions are regulated by the fitting of the positioning pins 37a and 37b and the positioning holes 41a and 41b, respectively, so that the positioning is performed.

  Further, when the upper surface of the platen 23 abuts against the stepped portions of the positioning pins 37a and 37b and the tip surfaces of the positioning pins 37c and 37d, the head frame 30 and the belt platen 18 are positioned in the vertical direction (Z-axis direction). This is a configuration in which positioning is performed. As described above, the positioning pin and the positioning hole serve as a restricting portion that positions the belt platen 18 and the head frame 30. In this embodiment, the positioning pins 37a, 37b, 37c and 37d are provided in the head frame 30 and the positioning holes 41a and 41b are provided in the platen 23. However, the positioning holes 41a and 41b are provided in the head frame 30 and the platen 23 is provided. Positioning pins 37a, 37b, 37c, and 37d may be provided on the surface.

  On the other hand, the head frame 30 is stacked and held on the apparatus main body frame 39 by a total of three points, that is, two points on the upstream side of conveyance of the sheet 3 and one point on the downstream side. Among them, the two points on the upstream side of the conveyance commonly use positioning pins 37a and 37b for positioning with the belt platen 18, and the positioning pins 37a and 37b are fitted into positioning holes (not shown) provided in the apparatus main body frame 39. To do. Thus, the head frame 30 is positioned on the apparatus main body frame 39.

  Next, the configuration of the registration roller pair 15 and the adjustment mechanism of the registration roller pair 15 will be described in detail.

  On both side surfaces of the head frame 30, arms 43 a and 43 b that are positioned and fixed toward the upstream side of conveyance of the sheet 3 are extended. A pair of registration rollers 15 is held at the tips of these arms 43a and 43b. The arms 43a and 43b are positioned and fixed to the head frame 30. The driving rollers 15a of the registration roller pair 15 are held at the ends of the arms 43a and 43b that are not fixed to the head frame 30 via the driving bearings 44a and 44b.

  A bearing fitting hole is formed in each of the arms 43a and 43b. Among these, the bearing fitting hole of one arm 43b has a perfect circle shape, and holds the outer shape of the drive bearing 44b all around. On the other hand, the bearing fitting hole of the other arm 43a is formed as a ring guide hole 45 that is substantially parallel to the nozzle surface and the conveying surface of the head and has a long hole shape. Two external shapes of the drive bearing 44a are held in contact with the side surface of the short side of the long hole of the ring guide hole 45.

  Further, a slide member 46 is attached to the arm 43a, and the slide member 46 is provided with a hole for holding the entire outer periphery of the drive bearing 44a. That is, the drive bearing 44a is held by two plates, the slide member 46 and the arm 43a. The slide member 46 has a guide long hole 47a having a long hole shape substantially parallel to the nozzle surface and the transport surface of the head.

  Two external points of the guide pin 48a fixed to the arm 43a are in contact with and guided by the side surface of the short side of the long hole. That is, the drive bearing 44a is inserted into the ring guide hole 45 provided in the arm 43a, and the guide pin 48a is inserted into the guide long hole 47a provided in the slide member 46, thereby using the two long holes as guides. The slide member 46 is movable in the conveyance direction of the sheet 13.

  The slide member 46 is biased by the compression spring 49 in the conveyance direction of the sheet 13 with respect to the arm 43a. Further, the compression spring 49 has an adjustment screw 50 for connecting the slide member 46 and the arm 43a. When the adjustment screw 50 is rotated in a predetermined direction, the slide member 46 is moved in the conveyance direction of the sheet 13 while being urged by the compression spring 49 with respect to the arm 43a.

  Accordingly, when the slide member 46 held by the arm 43a moves in the conveyance direction of the sheet 13, the drive bearing 44a held by the slide member 46 moves. Then, the drive roller 15a is configured to be able to change the angle θ in the transport direction with the other non-moving drive bearing 44b as a fulcrum (see FIG. 8).

  Here, the ring guide hole 45 and the guide long hole 47a are both long holes, but the present invention is not limited to this, and the drive roller 15a moves so as to be parallel to the conveyance direction of the sheet 13. Any shape may be used.

  On the other hand, the driven roller 15b of the registration roller pair 15 is urged by the driving roller 15a. Both ends of the driven roller 15b are held by the urging plates 53a and 53b via the driven bearings 54a and 54b. The biasing plate 53 a on the side where the slide member 46 is provided is held by a fulcrum pin 55 a fixed to the slide member 46. Further, the biasing plate 53b on the side where the slide member 46 is not provided is held by a fulcrum pin 55b fixed to the arm 43b. The urging plates 53a and 53b are rotatably held around the fulcrum pins 55a and 55b, respectively. The urging springs 56a and 56b urge the driven roller 15b to the drive roller 15a. It is configured.

  Since the biasing plate 53a on the side where the slide member 46 is provided is held by the slide member 46, when the slide member 46 is moved in the transport direction of the sheet 13, the biasing plate 53a is also integrated. Move. That is, the driving roller 15a and the driven roller 15b are configured to be integrated and the angle thereof can be varied.

  The drive mechanism of the drive roller 15a is disposed on the side where the slide member 46 is not provided. The driving roller 15 a is connected to the registration motor 60 via a registration clutch 57 and connection gears 58 a and 58 b that are connected to a gear formed on the registration clutch 57. Thereby, the drive of the registration motor 60 is transmitted to the drive roller 15a.

  Between the arms 43a and 43b, an upper registration guide 16a and a lower registration guide 16b are arranged vertically opposite to each other so as to be fixed to the arms 43a and 43b in parallel with the registration roller pair 15. A distance suitable for the sheet 13 to pass between the upper registration guide 16a and the lower registration guide 16b. Thus, the sheet 13 conveyed from the pickup roller 14 is guided to the registration roller pair 15 and further guided from the registration roller pair 15 to the belt platen 18.

  Next, the operation of the image forming apparatus in the first embodiment will be described.

  First, when power is input to the image forming apparatus 10 and an image forming instruction is input from an operation panel (not shown) of the image forming apparatus 10, a lifting mechanism is provided from a control unit (not shown) of the image forming apparatus 10. 27 raises the belt platen 18. As the belt platen 18 is raised, the positioning holes 41a and 41b formed in the platen 23 are fitted to the positioning pins 37a and 37b fixed to the lower surface of the head frame 30, and the head frame 30 and the belt platen are fitted. 18 positioning is performed.

  When the belt platen 18 is further raised, the stepped portions of the positioning pins 37a and 37b and the bottom surfaces of the positioning pins 37c and 37d abut against the upper surface of the platen 23, and the head frame 30 and the belt platen 18 are positioned in the vertical direction. . Due to the abutment, the driving of the elevating mechanism 27 is stopped by a control unit (not shown).

  Thereafter, the registration roller pair 15, the belt driving roller 20, and the paper discharge roller pair 33 are driven, and then the pickup roller 14 is driven. As a result, the uppermost sheet 3 placed in the paper feed tray 12 is taken out from the paper feed tray 12 by the pickup roller 14. Then, the sheet 3 is sent between the upper registration guide 16a and the lower registration guide 16b on the upstream side of the registration roller pair 15 in the paper conveyance direction.

  The sheet 13 reaches the gripping portion (nip portion) formed by the opposing portion of the driving roller 15a and the driven roller 15b of the registration roller pair 15 while being guided by the upper registration guide 16a and the lower registration guide 16b. To do. At this time, the rotation of the drive roller 15 is temporarily stopped by the registration clutch 57. As a result, the sheet 13 conveyed toward the registration roller pair 15 hits the grip portion, and is temporarily stopped by the registration roller pair 15 that is temporarily stationary, and the conveyed posture is forced. That is, if the sheet 13 has skew, the skew is corrected.

  Then, after a predetermined time, the rotation restraint by the registration clutch 57 is released, the rotation of the driving roller 15a is started, and the driven roller 15b is also started to follow the driving roller 15a. Thus, the sheet 13 passes between the upper registration guide 16a and the lower registration guide 16b while being guided, and is sent out onto the belt 19 of the belt platen 18 at a predetermined speed.

  On the belt 19, suction forces by the suction fans 24 a and 24 b are applied through innumerable holes provided in the platen 23 and innumerable holes provided in the belt 19. The sheet 13 fed from the registration roller pair 15 onto the belt 19 is rotated by a belt driving roller 20 rotated by a driving source (not shown) and a belt driven roller 21 driven by the belt driving roller 20 as shown in FIG. In this state, the belt 19 is circulated and moved in the clockwise direction, and is conveyed in the X direction at a predetermined conveyance speed while being adsorbed by the aforementioned suction force.

  Then, the sheet 3 conveyed by the belt 19 of the belt platen 18 is applied to the head frame 30 corresponding to each color of black (K), cyan (C), magenta (M), and yellow (Y). The ink is transported under the ink heads 31k, 31c, 31m, and 31y that are mounted and arranged. Then, ink droplets are ejected from the ink heads 31 k, 31 c, 31 m, 31 y onto the sheet 13 at the timing when the image formation position is reached, and an image is recorded on the sheet 13. Then, the sheet 13 on which the images of the respective colors are overlapped and recorded is discharged out of the apparatus by the discharge roller pair 33 and is placed and accommodated in the discharge tray 34.

  The head frame 30 is assembled by adjusting the positions of the ink heads 31k, 31c, 31m, and 31y with reference to the positioning pins 37a and 37b, and the belt platen 18 is positioned so that the positioning pins 37a and 37b are fitted. The belt conveyance direction is adjusted with reference to the holes 41a and 41b, and assembly is performed.

  Since the head frame 30 and the belt platen 18 are assembled and adjusted based on the same reference and are positioned based on the same reference when forming an image, the ink heads 31k, 31c, 31m, and 31y stacked on the head frame 30 are positioned. The nozzle row and the conveying direction of the sheet 13 by the belt platen 18 are maintained at a substantially right angle. However, even when the positional relationship between the belt platen 18 and each of the ink heads 31k, 31c, 31m, and 31y is secured during image formation, the rear end of the sheet 13 comes out of the gripping portion of the registration roller pair 15, and the belt platen When the sheet 13 is transferred onto the sheet 18, if there is an angle error between the conveyance direction of the sheet 13 of the registration roller pair 15 and the conveyance direction of the sheet 13 of the belt platen 18, the sheet 13 The transport direction changes, and image unevenness occurs in the image formed on the sheet 13.

  For example, when attention is paid to the overlapped color of black and yellow by the ink head 31k and the ink head 31y, the overlap state may be different between the leading edge and the trailing edge of the sheet 13. When such image unevenness is recognized, it is necessary to make an adjustment so that the conveyance direction of the sheet 13 by the pair of registration rollers 15 and the conveyance direction of the sheet 13 by the belt platen 18 coincide.

  In the adjustment, the conveyance direction of the sheet 13 by the belt platen 18 can be adjusted in accordance with the conveyance direction of the sheet 13 by the registration roller pair 15. However, if the conveyance direction of the sheet 13 by the belt platen 18 is adjusted, the nozzle rows of the ink heads 31k, 31c, 31m, and 31y are positioned at right angles to the conveyance direction of the sheet 13 by the belt platen 18. The relationship will not be maintained. In this case, the angle adjustment of the ink heads 31k, 31c, 31m, and 31y is required in accordance with the conveyance direction of the sheet 13 by the belt platen 18.

  According to the present embodiment, the conveyance direction of the sheet 13 by the registration roller pair 15 is adjusted, whereby the conveyance direction of the sheet 13 by the registration roller pair 15 and the conveyance direction of the sheet 13 by the belt platen 18 are adjusted. Are matched. The screw fixing the slide member 46 fixed to the arm 43a is loosened, and the adjustment screw 50 connecting the arm 43a and the slide member 46 rotates in a predetermined direction. Then, by the rotation of the adjusting screw 50, the slide member 46 is driven by the drive guide 44a and the ring guide hole 45 formed in the arm 43a, and the guide pin 48a fixed to the arm 43a and the guide length formed in the slide member 46. It is guided by the hole 47a. As a result, the sheet 13 is moved in the conveyance direction. One end of the driving roller 15a of the registration roller pair 15 is held by the slide member 46 via the driving bearing 44a, and the other end is held by the opposite arm 43b via the driving bearing 44b. Therefore, the drive roller 15a rotates by a predetermined angle with respect to the direction orthogonal to the transport direction of the sheet 13 with the drive bearing 44b held by the arm 43b and having no slide member 46 as a fulcrum. It is moved (moved). More specifically, the belt platen is rotated (moved) while maintaining a state substantially parallel to the conveying surface of the belt platen. Since the screw hole for fixing the slide member 46 has a playable shape, the slide member 46 can be fixed to the arm 43a again with a fixing screw after adjusting the position of the slide member 46. . One end of the driven roller 15b is also held by the biasing plate 53a held by the slide member 46, and the other end is held by the biasing plate 53b held by the opposite arm 43b. Therefore, the driven roller 15b is synchronized with the driving roller 15a. Thus, the angle of the driven roller 15b is also variable. That is, the angle of the drive roller 15a and the driven roller 15b is made variable while the parallelism between the drive roller 15a and the driven roller 15b is ensured.

  In the image formed on the sheet 13, the registration of the pair of registration rollers with respect to the conveyance direction of the sheet 13 by the belt platen 18 is checked while checking the overlapping state of the ink at the leading edge and the trailing edge of the sheet 13. 15, the conveyance direction of the sheet 13 is adjusted. In addition, in the image formed on the sheet 13, the overlapping state of the ink is checked at the leading edge and the trailing edge of the sheet 13, and the adjustment is performed by reading the image with a scanner or a CCD. For example, the adjustment amount is automatically calculated by calculating the deviation amount of the ink landing, and the adjustment screw 50 is rotated in accordance with the adjustment value based on the result.

  This adjustment eliminates the need to adjust the angle between the belt platen 18 and each of the ink heads 31k, 31c, 31m, and 31y, and simplifies the adjustment. This is also effective when the registration roller pair 15 is periodically replaced.

  Before the registration roller pair 15 is replaced, an image may be disturbed when the registration roller pair 15 is replaced with an apparatus that realizes high image quality. This is due to a tolerance of parts of the registration roller pair 15 itself and an attachment error. Since the high image quality can be realized before the replacement, the positional relationship between the belt platen 18 and each of the ink heads 31k, 31c, 31m, and 31y is properly maintained, so that only the registration roller pair 15 is adjusted. good.

  Each of the ink heads 31k, 31c, 31m, and 31y held by the head frame 30 is assembled with the positioning pins 37a and 37b adjusted in position and angle, so that unit guarantee is performed and the belt platen 18 Also, the unit guarantee is performed by adjusting the conveying direction of the belt 19 with respect to the positioning pins 37a and 37b provided on the jig.

  When assembled as an image forming apparatus, the positioning pins 17a and 37b of the head frame 30 are fitted into the positioning holes 17a and 17b of the belt platen 18 to be positioned, so that each ink fixed to the head frame 30 is fixed. The right angles of the heads 31k, 31c, 31m, 31y and the conveying direction of the belt platen 18 are secured.

  On the other hand, the registration roller pair 15 is held by the arms 43 a and 43 b extended from the head frame 30 without being held by the apparatus main body frame 39. The head frame 30 is positioned with respect to the apparatus main body frame 39 by using positioning pins 37 a and 37 b for positioning with the belt platen 18.

  With the above configuration, the apparatus is configured based on the positioning pins 37a and 37b of the head frame 30, so that even if some distortion occurs in the apparatus main body frame 39, the head frame 30, the belt platen 18, the registration roller pair. 15. The positional accuracy of each of the apparatus main body frames 39 is maintained, and stable high-quality image formation can be realized.

  Further, the angle of the registration roller pair 15 can be adjusted with respect to the head frame 30 and the belt platen 18 which are guaranteed by the positioning pins 37a and 37b. As compared with the method of adjusting each of the ink heads 31k, 31c, 31m, 31y and the belt platen 18 with respect to the transport direction of the leaf paper 13, an image forming apparatus capable of simplifying the adjustment can be provided.

  In the first embodiment described above, a method of fixing the separate arms 43a and 43b to the head frame 30 is adopted. However, the head frame 30 may be integrally extended. . In the adjustment of the registration roller pair 15, the method of the adjusting screw 50 is adopted, but a fine screw feeding mechanism such as a micrometer head may be adopted. Furthermore, although the adjustment screw 50 is driven manually in the present embodiment, a configuration may be adopted in which a gear and a motor are connected to the adjustment screw 50 for automatic adjustment.

  In this embodiment, the ink heads 31k, 31c, 31m, and 31y are configured as a line head with a plurality of heads arranged in a staggered manner, but one long line head per color. It is good also as a structure of.

(Modification)
In the first embodiment described above, the positioning of the head frame 30 and the arms 43a and 43b is not described in detail. However, as a modification, the configuration shown in FIG. 9 or FIG. 10 may be adopted. good.

  Regarding the positioning pins 37a and 37b for positioning the belt platen 18 and the head frame 30, in the first embodiment, the positioning pins 37a and 37b are attached to the lower surface of the head frame 30 in a suspended state. Alternatively, as shown in FIG. 10, at least the positioning pins 37 a and 37 b may be provided so as to penetrate above the head frame 30. In this case, holes for fitting to the positioning pins 37a and 37b are provided in the arms 43a and 43b for positioning.

  With this configuration, the positioning pins 37a and 37b for positioning the head frame 30 and the belt platen 18 are also used for positioning the arms 43a and 43b and the head frame 30. It becomes pins 37a and 37b. Therefore, since the unit guarantee standard for each unit can be unified, it is possible to improve the assembly accuracy when each unit is assembled.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.

  In the second embodiment, the basic configuration of the image forming apparatus is the same as that of the first embodiment shown in FIGS. 1 to 8 and the modification shown in FIGS. The same applies to the basic operation. Therefore, for these configurations and operations, the same reference numerals are assigned to the same parts, and illustration and description thereof will be omitted, and only the configurations and operations of different parts will be described.

  In the first embodiment described above, the registration roller is adjusted directly with respect to the registration roller. However, in the second embodiment, the adjustment is performed by adjusting the arm that holds the registration roller. A portion for fixing (holding) the arm to the head frame is fixed (held) with reference to a positioning pin provided on the head frame. The arm adjusts the angle by using one of the positioning pins as a rotation center and loosely fitting the other.

  Hereinafter, the second embodiment of the present invention will be described with reference to FIGS. 11 to 17.

  FIG. 11 is a perspective view showing a relationship between a belt platen serving as a transport mechanism, a head frame, and a registration roller pair during image formation of the image forming apparatus according to the second embodiment of the present invention. FIG. FIG. 13 is a detailed view showing the adjustment unit of the registration roller pair of the image forming apparatus in the second embodiment from above. FIG. 13 is a holding unit of the registration roller pair of the image forming apparatus in the second embodiment of the present invention. FIG. 14 is a detailed view showing the holding and driving unit of the registration roller pair of the image forming apparatus according to the second embodiment of the present invention, and FIG. 15 is a detailed view showing the second embodiment of the present invention. FIG. 16 is a detailed view showing the holding and driving unit of the registration roller pair of the image forming apparatus. FIG. 16 is a partial detailed view of the adjusting unit of the registration roller pair of the image forming apparatus according to the second embodiment of the present invention. In the second embodiment of the present invention An image forming apparatus, which is a diagram of the adjustment direction of the registration roller pair as seen from above the apparatus. However, FIG. 17 exaggerates the adjustment angle for explanatory purposes.

  First, the configuration of the registration roller pair 15 will be described in detail.

  The head frame 30 is positioned and held by an adjustment arm 65 having a shape extending toward the upstream side of conveyance of the sheet 13. A registration roller pair 15 is held at the tip of the adjustment arm 65. The adjustment arm 65 is positioned on the head frame 30 by positioning pins 37a and 37b for positioning the head frame 30 and the belt platen 18. The positioning pins 37 a and 37 b are provided so as to penetrate the upper surface of the head frame 30.

  The adjustment arm 65 is provided with a hole that fits the outer shape of the positioning pin 37a at a position corresponding to the positioning pin 37a, and the positioning pin 37a is fitted therein. On the other hand, an arc hole 67 having a long hole shape on an arc is provided at a position corresponding to the positioning pin 37b, and the positioning pin 37b is inserted therein. The positioning pins 37a and 37b are provided with urging rings 66a and 66b to prevent the adjustment arm 65 from coming off.

  Two opposing side surfaces (arm portions 68a and 68b) are formed on the extended tip of the adjustment arm 65 on the side not fixed to the head frame 30 so that the registration roller pair 15 can be disposed therebetween. Has been. The driving roller 15a of the registration roller pair 15 is rotatably supported at both ends by arm portions 68a and 68b via driving bearings 44a and 44b.

  On the other hand, the driven roller 15b of the registration roller pair 15 is urged by the driving roller 15a. The arm portions 68a and 68b of the adjustment arm 65 are provided with urging plates 53a and 53b that are rotatably held by fulcrum pins 55a and 55b, respectively. The driven roller 15b is rotatably held at both ends via the urging plates 53a and 53b via the driven bearings 54a and 54b. The urging plates 53a and 53b are configured such that the driven roller 15b is urged to the driving roller 15a by the urging springs 56a and 56b.

  The drive mechanism of the drive roller 15a is disposed with respect to the one arm portion 68b. The driving roller 15a is connected to the registration motor 60 via a gear formed on the registration clutch 57 and connection gears 58a and 58b. Thereby, the driving of the registration motor 60 is transmitted to the driving roller 15a.

  Next, the adjustment mechanism of the registration roller pair 15 will be described.

  Another cam clutch 71 is fixed to the tip of the registration motor 60 described above. A cam gear 72 that is integrated with the cam is disposed so as to be connected to the cam clutch 71. When the drive roller 15a is driven, when the rotational drive is transmitted to the drive roller 15a by the registration clutch 57, the connection by the cam clutch 71 is released and the rotational drive is not transmitted to the cam gear 72. . Further, when the rotational drive is transmitted to the cam gear 72, the rotational drive of the registration motor 60 is transmitted to the cam gear 72 by the cam clutch 71. At this time, the connection by the registration clutch 57 is released, and the rotational drive is not transmitted to the drive roller 15a.

  The adjustment arm 65 is configured so that tension is applied to the head frame 30 by a spring 73. That is, the spring 73 is tensioned so that the cam portion of the cam gear 72 fixed to the adjustment arm 65 contacts the contact portion 74 of the head frame 30. With the screw fixing the adjustment arm 65 loosened, the registration clutch 57 is released, the connection to the drive roller 15 a is released, and the cam clutch 71 is connected to the cam gear 72. When the registration motor 60 is driven in this state, the cam gear 72 is rotated, and the cam portion formed on the cam gear 72 rotates while being in contact with the contact portion 74 of the head frame 30. The adjustment arm 65 is biased by the spring 73 with respect to the cam gear 72. Therefore, the adjusting arm 65 rotates along the circular arc hole 67 about the positioning pin 37a as a rotation center (fulcrum) along the locus of the cam. As the adjustment arm 65 rotates, the registration roller pair 15 held by the adjustment arm 65 is configured to be moved by a predetermined angle with respect to a direction orthogonal to the conveyance direction of the sheet 13. At this time, the registration roller pair 15 (adjustment arm 65) is moved in a state where the registration roller pair 15 (adjustment arm 65) is maintained substantially parallel to the conveying surface of the belt platen.

  Between the arm portions 68a and 68b, an upper registration guide 16a and a lower registration guide 16b are arranged vertically opposite to each other so as to be fixed to the arm portions 68a and 68b in parallel with the registration roller pair 15. The upper registration guide 16a and the lower registration guide 16b are arranged at a distance suitable for the sheet 13 to pass between them. As a result, the sheet 13 conveyed from the pickup roller 14 is guided to the registration roller pair 15 and further from the registration roller pair 15 to the belt platen 18.

  Next, an operation in the image forming apparatus having the configuration according to the second embodiment will be described.

  According to the second embodiment, the conveyance direction of the sheet 13 by the registration roller pair 15 is adjusted, whereby the conveyance direction of the sheet 13 by the registration roller pair 15 and the sheet 13 by the belt platen 18 are adjusted. The transport directions are matched.

  First, a screw fixed to the adjustment arm 65 and fixing the adjustment arm 65 is loosened. Then, the operation of the operation panel (not shown) releases the connection of the registration clutch 57 connected to the drive roller 15a. Next, the cam clutch 71 connected to the cam gear 72 is connected.

  When the registration motor 60 is driven in a state where the cam portion of the cam gear 72 is urged by the spring 73 against the abutting portion 74 of the head frame 30, the cam gear 72 is rotated and the cam portion formed on the cam gear 72 is driven. Rotates while contacting the contact portion 74 of the head frame 30. The adjustment arm 65 is biased with respect to the cam gear 72. Therefore, the adjusting arm 65 rotates along the arc hole 67 with the positioning pin 37a as the rotation center (fulcrum) along the locus of the cam, and the angle of the registration roller pair 15 held by the adjusting arm 65 can be changed. Become.

  Since the screw hole for fixing the adjustment arm 65 has a playable shape, the adjustment arm 65 can be fixed to the head frame 30 again with a fixing screw after adjusting the position of the adjustment arm 65. it can.

  Since the driven roller 15b is also held by the urging plates 53a and 53b held by the adjustment arm 65, the angle of the driven roller 15b can be changed in synchronization with the drive roller 15a. That is, the angle of the drive roller 15a and the driven roller 15b can be changed integrally while the parallelism of the drive roller 15a and the driven roller 15b is ensured.

  Since the upper registration guide 16 a and the lower registration guide 16 b are also fixed to the adjustment arm 65, the angle can be changed integrally while maintaining the positional relationship with the registration roller pair 15.

  In the image formed on the sheet 13, a pair of registration rollers is checked with respect to the conveying direction of the sheet 13 by the belt platen 18 while checking the overlapping state of the ink at the leading and trailing ends of the sheet 13. 15, the conveyance direction of the sheet 13 is adjusted.

  In addition, in the image formed on the sheet 13, as a method for checking the overlapping state of the ink at the leading edge and the trailing edge of the sheet 13 and adjusting it, the image is read by a scanner, a CCD, etc. For example, a method of automatically calculating an adjustment amount by calculating an amount of landing deviation and rotating the registration motor 60 in accordance with an adjustment value based on the result may be used.

  As a result, as in the first embodiment described above, the angle adjustment between the belt platen 18 and each of the ink heads 31k, 31c, 31m, and 31y becomes unnecessary, and the adjustment can be simplified. Further, according to the present embodiment, since the adjustment of the registration motor 60 is utilized and the adjustment is performed by the cam gear 72, the angle of the registration roller pair 15 can be finely adjusted with a simple configuration.

  Further, the driving roller 15a, the driven roller 15b, the upper registration guide 16a and the lower registration guide 16b are held by the adjustment arm 65. By making the angle of the entire adjustment arm 65 variable, the positional accuracy of each component is improved. Adjustment can be performed while being securely held.

  The configuration of the ink heads 31k, 31c, 31m, and 31y is a line head composed of a plurality of heads arranged in a staggered manner as in the first embodiment described above, but one for each color. It is good also as a structure of a long line head.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings.

  In the third embodiment, the basic configuration of the image forming apparatus is the same as that of the first embodiment shown in FIGS. 1 to 8, the modification shown in FIGS. This is the same as the second embodiment shown in FIGS. 11 to 17, and the basic operation is also the same. Therefore, for these configurations and operations, the same reference numerals are assigned to the same parts, and illustration and description thereof will be omitted, and only the configurations and operations of different parts will be described.

  Hereinafter, the third embodiment of the present invention will be described with reference to FIGS.

  FIG. 18 is a side view schematically showing an image forming apparatus according to the third embodiment of the present invention, and FIG. 19 is a diagram illustrating conveyance during image formation of the image forming apparatus according to the third embodiment of the present invention. FIG. 20 is a perspective view showing a relationship between a belt platen as a mechanism, a head frame, and a registration roller pair. FIG. 20 shows details of a holding unit and an adjustment unit of the registration roller pair of the image forming apparatus according to the third embodiment of the present invention. FIG. 21, FIG. 21 is a detailed view showing the holding and driving unit of the registration roller pair of the image forming apparatus in the third embodiment of the present invention, and FIG. 22 is an image forming apparatus in the third embodiment of the present invention. FIG. 23 is an exploded view of the driving roller holding portion for the belt platen of the image forming apparatus according to the third embodiment of the present invention.

  First, the configuration of the registration roller pair 15 and the adjustment mechanism of the registration roller pair 15 will be described in detail.

  The platen frames 26 a and 26 b of the belt platen 18 have a shape extending toward the upstream side of conveyance of the sheet 13. An adjustment plate slide member 46 is held on the extended portion of the platen frame 26a so that the position thereof can be adjusted, and a holding plate 77 is positioned and fixed on the extended portion of the platen frame 26b. Yes. A pair of registration rollers 15 is held between the slide member 46 and the holding plate 77 via a bearing.

  The slide member 46 has two long holes, a ring guide hole 78 and a guide long hole 79a. The ring guide hole 78 and the guide long hole 79a are formed into long holes in a direction substantially parallel to the nozzle surface and the transport surface of the head. In the ring guide hole 78, a guide bearing 80a in which the front end shaft of the belt driven roller 21 is fitted inside is inserted so as to maintain its outer shape. A guide pin 48a provided on the platen frame 26a is inserted into the guide long hole 79a. Thereby, the position of the slide member 46 is regulated and held by the platen frame 26a.

  Further, the slide member 46 has a guide bearing 80 a inserted into a ring guide hole 78 provided in the slide member 46, and a guide pin 48 a is inserted into a guide long hole 79 a provided in the slide member 46. The slide member 46 can be moved in the transport direction of the sheet 13 using one long hole as a guide.

  On the other hand, the holding plate 77 has one perfect circular hole and one guide long hole 79b. Among these, the guide long hole 79b has a shape in which the direction substantially parallel to the nozzle surface and the transport surface of the head is the longitudinal direction, like the slide member 46. Further, the perfect circular hole is provided on the axis of the belt driven roller 21. The outer shape of the guide bearing 80b in which the tip shaft of the belt driven roller 21 is fitted inward is fitted in the perfect circle hole. A guide pin 48b provided on the platen frame 26b is inserted into the guide long hole 79b. Thereby, the position of the holding plate 77 is held by the platen frame 26b.

  The drive roller 15a is rotatably held by the slide member 46 and the holding plate 77 via drive bearings 44a and 44b. Accordingly, when the slide member 46 held by the platen frame 26a moves in the transport direction of the sheet 13, the drive bearing 44a held by the slide member 46 moves. Then, the drive roller 15a is configured to be able to change the angle with the drive bearing 44b held by the other holding plate 77 as a fulcrum. A cam gear 72 is rotatably held on the platen frame 26a. A movable gear 82 is provided so as to be connected to the cam gear 72. The cam gear 72 includes a cam portion 72 a that contacts the abutting portion 74 of the slide member 46 and a gear portion 72 b that meshes with the movable gear 82.

  On the other hand, since the movable gear 82 has a shape in which screws are integrally formed, when the movable gear 82 is rotated, the movable gear 82 moves in the axial direction of the screw according to the pitch of the screw. That is, by setting the number of teeth of the movable gear 82 to be smaller than the number of teeth formed on the cam gear 72, the number of rotations of the cam gear 72 can be reduced with respect to the number of rotations of the movable gear 82, The rotation of the cam gear 72 can be finely adjusted.

  Further, since the movable gear 82 moves in the axial direction of the screw depending on the pitch of the screw, the gear width is set wide so that the movable gear 82 does not come off the cam gear 72 even if the movable gear 82 moves.

  Further, half of the cam portion 72a of the cam gear 72 forms a smooth cam curve, and the other half has a plurality of surfaces processed at an arbitrary adjustment pitch. In the slide member 46, tension is applied by the spring 43 in a direction in which the contact portion 44 provided on the slide member 46 is urged against the cam gear 72. Here, when the movable gear 82 is rotated in a state where the screw fixing the slide member 46 is loosened, the cam gear 72 rotates in conjunction with the cam portion 72a formed on the cam gear 72. It rotates while contacting the abutment portion 44. Since the slide member 46 is biased with respect to the cam gear 72, the guide bearing 80a and the guide pin 48a are along the long hole shapes of the ring guide hole 78 and the guide long hole 79a, respectively, along the locus of the cam. Move while being guided. As a result, the registration roller pair 15 is moved in a state in which the registration roller pair 15 is maintained substantially parallel to the conveying surface of the belt platen.

  On the other hand, the driven roller 15b of the registration roller pair 15 is urged by the driving roller 15a. Both ends of the driven roller 15b are held by the urging plates 53a and 53b via the driven bearings 54a and 54b. The urging plates 53a and 53b are held by the slide member 46 and fulcrum pins 55a and 55b fixed to the holding plate 77, respectively. The urging plates 53a and 53b are rotatably held around the fulcrum pins 55a and 55b, respectively, and the driven roller 15b is urged to the driving roller 15a by the urging springs 56a and 56b. It is configured.

  Since the biasing plate 53a on the side where the slide member 46 is provided is held with respect to the slide member 46, if the slide member 46 is moved in the transport direction of the sheet 13, the biasing plate 53a also Moves together in the transport direction. In other words, the driving roller 15a and the driven roller 15b are integrated so that the angle can be changed.

  The drive mechanism of the drive roller 15a is disposed on the side where the slide member 46 is not provided. The drive roller 15a is connected to the registration motor 57 via a registration clutch 57 and connection gears 58a and 58b, and the drive of the registration motor 60 is transmitted to the drive roller 15a.

  Between the slide member 46 and the holding plate 77, an upper registration guide 16 a and a lower registration guide 16 b are disposed in parallel with the registration roller pair 15 so as to face each other in the vertical direction. The upper registration guide 16a and the lower registration guide 16b are arranged at a distance suitable for the sheet 13 to pass between the upper registration guide 16a and the lower registration guide 16b. It is held in a certain state.

  By the upper registration guide 16a and the lower registration guide 16b, the sheet 13 conveyed from the pickup roller 14 is guided to the registration roller pair 15, and further from the registration roller pair 15 to the belt platen 18.

  Next, an operation in the image forming apparatus 10a having the above-described configuration will be described.

  According to this embodiment, the conveyance direction of the sheet 13 by the registration roller pair 15 and the conveyance direction of the sheet 13 by the belt platen 18 are adjusted by adjusting the conveyance direction of the sheet 13 by the registration roller pair 15. Match. The screw fixing the slide member 46 fixed to the platen frame 26a is loosened, and the movable gear 82 is rotated. When the cam gear 72 rotates in conjunction with the rotation of the movable gear 82, the cam portion 72 a formed on the cam gear 72 rotates while contacting the contact portion 74 of the slide member 46. Since the slide member 46 is biased by the spring 73 with respect to the cam gear 72, the slide member 46 is guided along the cam trajectory by a ring guide hole 78 formed in the guide bearing 80 a and the slide member 46. The guide pin 48a fixed to the platen frame 26a and a guide long hole 79a formed in the slide member 46 are guided to move in the transport direction of the sheet 13 (X direction in FIG. 18).

  One end of the driving roller 15a of the registration roller pair 15 is held by the driving bearing 44a held by the slide member 46, and the other end is held by the holding plate 77 on the opposite side via the driving bearing 44b. Therefore, the angle of the drive roller 15a can be changed with the drive bearing 44b held by the holding plate 77 as a fulcrum.

  Since the screw hole for fixing the slide member 46 has a play shape, after adjusting the position of the slide member 46, the slide member 46 is fixed to the platen frame 26a again with the fixing screw. be able to. Similarly, one end of the driven roller 15b is held by the biasing plate 53a held by the slide member 46, and the other end is held by the biasing plate 53b held by the holding plate 77 on the opposite side. . Therefore, the angle of the driven roller 15b can be changed in synchronization with the drive roller 15a. The driving roller 15a and the driven roller 15b can change the angle integrally while maintaining the parallelism of the driving roller 15a and the driven roller 15b.

  In the image formed on the sheet 13, the registration of the pair of registration rollers with respect to the conveyance direction of the sheet 13 by the belt platen 18 is checked while checking the overlapping state of the ink at the leading edge and the trailing edge of the sheet 13. 15, the conveyance direction of the sheet 13 is adjusted. Since the upper registration guide 16a and the lower registration guide 16b are also held on the holding plate 77 on one side and held on the slide member 46, the upper registration guide 16a and the lower registration guide 16b are also integrated with each other while maintaining the positional relationship with the registration roller pair 15. The angle can be changed.

  In addition, in the image formed on the sheet 13, as a method for checking the overlapping state of the ink at the leading edge and the trailing edge of the sheet 13 and adjusting it, the image is read by a scanner, a CCD, etc. For example, a method of automatically calculating an adjustment amount by calculating a deviation amount of landing and rotating the movable gear 82 according to an adjustment value based on the result can be used. As a result, as in the first embodiment described above, the angle adjustment between the belt platen 16 and each of the ink heads 31k, 31c, 31m, and 31y becomes unnecessary, and the adjustment can be simplified.

  Further, according to the third embodiment, the angle adjustment by the rotation of the cam gear 72 can be finely adjusted manually with a simple configuration of the movable gear 82 in which the gear and the screw are integrally formed. In addition, the cam portion 72a of the cam gear 72 has a half of a smooth cam curve, and the other half is configured as a shape having a plurality of surfaces processed at an arbitrary adjustment pitch. It is also possible to use properly depending on the situation.

  Further, since the registration roller pair 15 is held with respect to the belt platen 18, for example, as a method of positioning the initial position at the time of assembly, a jig contacting the shaft of the belt driven roller 21 is used as the registration roller pair 15. Adjustment at the time of assembling can be easily performed by providing the driving roller 15a and adjusting and fixing the driving roller 15a according to the belt driven roller 21.

  The ink head is configured as one long line head per color, but as in the first and second embodiments described above, a plurality of heads arranged in a staggered manner It is good also as composition to do. In the third embodiment, the rotational drive of the cam gear 72 is manually rotated using the movable gear 82. However, the cam gear 72 may be automatically adjusted by connecting a motor to the cam gear 72.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

1 is a side view schematically showing an image forming apparatus according to a first embodiment of the present invention. 1 is a perspective view schematically showing an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view of a head frame as a recording unit and a registration roller unit as a conveyance roller of the image forming apparatus according to the first exemplary embodiment as viewed from below. FIG. 3 is a perspective view illustrating a relationship between a belt platen serving as a conveyance mechanism, a head frame, and a registration roller pair during image formation of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a detailed view illustrating a registration roller pair holding and adjusting unit of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is a detailed view showing a holding portion and an adjustment portion of a registration roller pair of the image forming apparatus according to the first embodiment of the present invention from the back side. FIG. 3 is a detailed diagram illustrating a holding unit and a driving unit of a registration roller pair of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating an adjustment direction of a registration roller pair when the image forming apparatus according to the first embodiment of the present invention is viewed from above the apparatus. FIG. 10 is a perspective view for explaining positioning of a head frame and an arm of an image forming apparatus in a modification of the first embodiment of the present invention. FIG. 10 is a perspective view for explaining positioning of a head frame and an arm of an image forming apparatus in a modification of the first embodiment of the present invention. FIG. 10 is a perspective view illustrating a relationship between a belt platen serving as a conveyance mechanism, a head frame, and a registration roller pair during image formation of an image forming apparatus according to a second embodiment of the present invention. FIG. 7 is a detailed view showing an adjustment unit of a registration roller pair of an image forming apparatus according to a second embodiment of the present invention from above the apparatus. FIG. 10 is a detailed view illustrating a holding unit for a registration roller pair of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a detailed diagram showing a registration roller pair holding and driving unit of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a detailed diagram showing a registration roller pair holding and driving unit of an image forming apparatus according to a second embodiment of the present invention. FIG. 6 is a partial detail view of an adjustment unit of a registration roller pair of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is an explanatory diagram illustrating an adjustment direction of a registration roller pair when an image forming apparatus according to a second embodiment of the present invention is viewed from above the apparatus. FIG. 6 is a side view schematically showing an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a perspective view illustrating a relationship between a belt platen serving as a conveyance mechanism, a head frame, and a registration roller pair during image formation of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a detailed view illustrating a holding unit and an adjustment unit of a registration roller pair of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a detailed view showing a registration roller pair holding and driving unit of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a detailed view illustrating a shape of an adjustment cam of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is an exploded view of a driving roller holding portion for a belt platen of an image forming apparatus according to a third embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 10a ... Image forming apparatus, 11 ... Apparatus main body, 12 ... Paper feed tray, 13 ... Sheet paper (paper), 14 ... Pickup roller, 15 ... Registration roller pair, 15a ... Drive roller, 15b ... Drive roller, 16a ... upper registration guide, 16b ... lower registration guide, 18 ... belt platen, 19 ... belt, 20 ... belt drive roller, 21 ... belt driven roller, 22 ... tension roller, 23 ... platen, 24a, 24b ... suction fan, 26a, 26b ... Platen frame, 27 ... Elevating mechanism, 30 ... Head frame, 31k, 31c, 31m, 31y ... Ink head, 33 ... Paper discharge roller pair, 34 ... Paper discharge tray, 37a-37d ... Positioning pins, 39 ... Main body Frame, 43a, 43b ... Arm, 44a, 44b ... Drive bearing, 45 ... Ring guide hole, 4 ... Slide member, 47a ... Guide hole, 48a ... Guide pin, 49 ... Compression spring, 50 ... Adjustment screw, 53a, 53b ... Biasing plate, 54a, 54b ... Driven bearing, 55a, 55b ... Supporting pin, 57 ... Register Clutch, 58a, 58b ... coupling gear, 60 ... registration motor, 65 ... adjustment arm, 66a, 66b ... biasing ring, 67 ... arc hole, 68a, 68b ... arm part, 71 ... cam clutch, 72 ... cam gear, 73 ... spring 74 abutment portion 77 holding plate 78 ring guide hole 79 a 79 b guide long hole 80 a 80 b guide bearing 82 movable gear

Claims (12)

A transport mechanism for transporting the recording medium;
A line head disposed over at least the width of the recording medium in a direction orthogonal to the conveying direction of the recording medium conveyed by the conveyance mechanism;
A head frame that holds the line head substantially in parallel at a predetermined interval, and is disposed apart from the transport mechanism at a position facing the transport mechanism;
A restriction unit that is provided in the head frame and the transport mechanism, and regulates a mutual positional relationship between the head frame and the transport mechanism;
An arm that is provided integrally with the head frame, and that extends to the recording medium introduction side of the transport mechanism;
A registration roller that is held by the arm and restricts a conveying posture when the recording medium is introduced into the conveying mechanism and introduces the recording medium into the conveying mechanism;
An adjustment mechanism that adjusts the registration roller so that the conveyance direction of the recording medium introduced by the registration roller coincides with the conveyance direction of the recording medium conveyed by the conveyance mechanism;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the adjustment mechanism adjusts an angle of the registration roller in a state in which the adjustment mechanism maintains a state substantially parallel to a conveyance surface that conveys the recording medium. apparatus.   The adjustment mechanism is provided at one end of a shaft of the registration roller, and moves the registration roller by a predetermined angle in the conveyance direction of the recording medium with the other end serving as a fulcrum. Item 3. The image forming apparatus according to Item 2. The adjustment mechanism includes a slide member that holds the registration roller, and a moving member that moves the slide member relative to the arm.
By moving the slide member by the moving member, the registration roller is moved by a predetermined angle in a state in which the registration roller is maintained in a substantially parallel state with respect to a transport surface for transporting the recording medium of the transport mechanism. The image forming apparatus according to claim 1. The registration roller includes a driving roller and a driven roller that rotates following the driving roller. One end of the driving roller is held by the slide member via the arm, and one of the driven rollers Is held by a support plate rotatably supported by the slide member,
The image forming apparatus according to claim 4, wherein the adjustment mechanism further includes a biasing member for biasing the driven roller to the driving roller.   The image forming apparatus according to claim 5, wherein the adjustment mechanism adjusts an angle of the pair of registration rollers while maintaining parallelism between the driving roller and the driven roller.   The arm on one end side of the driving roller is formed with a long hole whose longitudinal direction is the conveyance direction of the recording medium, and the driving roller is supported by the long hole. The image forming apparatus according to 5.   The slide member is formed with a long hole whose longitudinal direction is the conveyance direction of the recording medium, and the arm is formed with a pin that engages with the long hole. 6. The image forming apparatus according to claim 4, wherein the moving direction of the slide member is restricted.   The restricting portion restricts a positional relationship between the transport mechanism and the head frame so that a transport direction of the recording medium by the transport mechanism is orthogonal to a direction in which the line head held by the head frame is disposed. The image forming apparatus according to claim 1.   10. The restricting portion has at least two restricting members on an introduction side of the recording medium of the head frame, and the arm is positioned by the at least two restricting members. Image forming apparatus.   The restricting portion includes at least two restricting members on the recording medium introduction side of the head frame, the arm is positioned by the at least two restricting members, and the adjusting mechanism is configured to include the at least two restricting members. The image forming apparatus according to claim 1, wherein the position of the registration roller is adjusted by rotating the arm with any one of the regulating members as a fulcrum. A transport mechanism for transporting the recording medium;
A line head disposed over at least the width of the recording medium in a direction orthogonal to the conveying direction of the recording medium conveyed by the conveyance mechanism;
A head frame that holds the line head substantially in parallel at a predetermined interval, and is disposed apart from the transport mechanism at a position facing the transport mechanism;
Provided on the recording medium introduction side of the head frame, and at least two regulating members for regulating the mutual positional relationship between the head frame and the transport mechanism;
The head frame is movably provided, and an arm extended to the recording medium introduction side in the transport mechanism;
A registration roller that is held by the arm and restricts a conveying posture when the recording medium is introduced into the conveying mechanism and introduces the recording medium into the conveying mechanism;
Comprising
The arm is positioned by the at least two restricting members, and rotates about one of the at least two restricting members as a fulcrum, thereby conveying the recording medium introduced by the registration rollers. And the registration roller is adjusted so that the conveyance direction of the recording medium conveyed by the conveyance mechanism coincides.

Images