JP4225316B2 - Sheet conveying device, image recording device - Google Patents

Description

  The present invention relates to a sheet conveying apparatus that nipping and conveying a sheet-like medium to be conveyed by a driving roller and a driven roller that is driven in pressure contact with the driving roller, and particularly to an image recording apparatus that includes the sheet conveying apparatus. The present invention relates to the pressure contact structure of the driven roller.

  Conventionally, in an ink jet image recording apparatus, as shown in FIG. 18, a recording sheet S fed from a sheet feeding cassette (not shown) is intermittently fed by a predetermined length toward a platen 102 that supports the recording sheet S. On the other hand, while the intermittent conveyance is stopped, the carriage 101 on which the recording head 100 is mounted is a direction orthogonal to the conveyance direction of the recording paper S (left and right direction in FIG. 18, hereinafter referred to as “sub-scanning direction”). The ink is ejected from the nozzles of the recording head 100 and adhered to the recording paper S while being slid in a direction perpendicular to the paper surface in FIG. 18 (hereinafter referred to as “main scanning direction”). To be recorded.

  The intermittent conveyance described above includes a pair of conveyance rollers 103 disposed on the upstream side of the platen 102 in the conveyance direction of the recording paper S, and a pair of conveyance rollers 103 disposed on the downstream side of the platen 102 in the conveyance direction of the recording paper S. The discharge roller pair 104 is rotated by a control unit (not shown).

  The conveying roller pair 103 includes a driving roller 105 that is driven by receiving a rotational force transmitted from a motor or the like, and a driven roller 106 that is pressed against the driving roller 105 by a coil spring 107. As shown in FIG. 18A, when the leading edge of the recording sheet S fed from the sheet feeding cassette enters the pressure contact portion of the conveying roller pair 103, the recording sheet S is rotated in a direction to return the recording sheet S to the upstream side in the conveying direction ( Further conveyance of the recording paper S to the downstream side in the conveyance direction is stopped by the conveyance roller pair 103 (corresponding to reverse rotation driving). Thereby, the skew of the recording paper S is corrected and the leading ends of the recording paper S are aligned. This operation is called so-called resist processing. The registration processing may be performed when the rotation of the conveyance roller pair 103 is stopped.

  When the registration process is performed, the driving roller 105 is rotationally driven in a direction in which the recording paper is conveyed downstream in the conveying direction. That is, it is driven to rotate forward. As a result, as shown in FIG. 18B, the recording sheet S is sandwiched between the driving roller 105 and the driven roller 106, and the conveyance of the recording sheet S by the conveying roller pair 103 is started. When the conveyance further proceeds, as shown in FIG. 18C, the trailing edge of the recording paper S comes out of the conveyance roller pair 103, and the recording paper S is conveyed only by the discharge roller pair 104. The discharge roller pair 104 includes a driving roller 108 and a driven roller 109 as in the case of the conveyance roller pair 103. The discharge roller pair 104 sandwiches the recording sheet S on which an image is recorded. For this reason, the pressure contact force is set to be small in order to prevent image deterioration.

  On the other hand, Patent Document 1 discloses a nip roller device in which the pressure-bonding direction of the driven roller is inclined by the same angle as the pressure angle caused by the engagement of a plurality of gears that transmit driving force from the driving roller to the driven roller. According to this, even if a rotational load is generated in the pressure angle direction, the nip pressure between the driving roller and the driven roller does not change.

JP-A-8-217285

  In the above-described conventional image recording apparatus, as shown in FIG. 19, the driven roller 106 supported so as to be movable in the direction perpendicular to the axis of the driven roller 106 and the axis of the driving roller 105, and the driven roller 106 are moved as described above. A coil spring 107 that biases in the same direction as the direction is disposed. FIG. 19 is an enlarged view showing details of the conveying roller pair 103. While the registration process is being performed on the recording paper S, as shown in FIG. 19A, the recording paper S is upstream of the pressure contact portion of the conveying roller pair 103 in the conveying direction and the leading end of each roller is Restrained in contact with the surface. When the registration process is performed for a predetermined time, the driving roller 105 is switched from the reverse rotation to the normal rotation in order to transport the recording paper S downstream in the transport direction. At this time, the rotation of the driving roller 105 is temporarily stopped (see FIG. 19B). Thereafter, the rotational force of the driving roller 105 is transmitted to the recording paper S. As a result, the driven roller 106 is retracted by the thickness h of the recording paper S against the coil spring 107, and the recording paper S is nipped by the conveying roller pair 103.

  However, at the moment when the recording paper S is sandwiched by the conveying roller pair 103, the spring force F1 of the coil spring 107 acts on the leading edge of the recording paper S and reacts from the recording paper S as shown in FIG. As a result, a reaction force F2 in a direction opposite to the spring force F1 acts on the surface of the driven roller 106. This reaction force F2 acts at a contact point Q upstream of the nip point P in the transport direction as shown in the figure. Accordingly, a rotational force F3 (component force of the reaction force F2) that reversely rotates the driven roller 106 by the spring force F1 and the reaction force F2 is generated. The spring force F1 is set to a relatively strong force so as not to cause a conveyance failure such as slipping when the recording paper is conveyed. The rotational force F3 rotates the driven roller 106 in the direction in which the recording paper S is returned to the upstream side in the transport direction (clockwise rotation in FIG. 19C), so that the driving roller 105 moves the recording paper S downstream in the transport direction. The action you are trying to do is diminished. As a result, slip occurs between the driving roller 105 and the recording paper S, and the amount of movement of the recording paper S in the downstream direction in the transport direction becomes smaller than a desired amount, or the amount of movement becomes non-uniform. Further, when the above-mentioned slip occurs partially in the width direction of the recording paper S, the recording paper S is skewed. As described above, the rotational force F3 in the clockwise direction acting on the driven roller 106 at the moment when the recording sheet S is sandwiched not only prevents the recording sheet S from entering the press contact portion, but also shifts the sandwiching timing of the recording sheet S. This is a problem because it causes the recording paper S to skew. Further, it is said that the so-called cueing amount secured at the leading edge of the recording paper S varies from recording paper to recording paper when the operation of matching the leading edge of the image recording area on the recording paper S with the image recording position is performed at the start of recording. Problems can also arise.

  Accordingly, the present invention has been made in view of the above circumstances, and the object of the present invention is to ensure that the leading end is clamped at the start of conveyance of a medium to be conveyed such as recording paper, It is an object of the present invention to provide a sheet conveying apparatus and an image recording apparatus that can prevent variations in the amount of cueing between the respective conveyed media.

(1) The present invention, and the conveying roller pair composed a driven roller that is pressed against the drive roller and the drive roller, which is driven to rotate driven, the driven roller rotation of the drive roller of the pressure contact state along a direction forming an angle of inclination α with respect to the first plane including the rotational axis of the shaft and the driven roller movably supported, retractable from the drive roller and the conveyance direction downstream side of the conveying roller pair And a biasing force that is provided on the downstream side in the transport direction with respect to the plane including the rotation axis of the driven roller and that presses the driven roller against the driving roller. Urging means to be added to the driven roller, and the inclination angle α is such that the corner in the thickness direction of the tip of the medium to be conveyed entering the pressure contact portion of the conveyance roller pair in the pressure contact state is the drive roller and Both driven rollers In a state where the roller surfaces are in contact, and a second plane including the rotation axis of the contact point and the driven roller between the corner portion and the roller surface of the driven roller of the conveyed medium, and the said first plane The sheet conveying apparatus is configured to be larger than the angle β formed.

  As described above, since the inclination angle α is set to be larger than the angle β, the driven roller is rotated forward by the pressing force acting on the transported medium and the reaction force when the transported medium is sandwiched by the transporting means. A rotational force is generated in the direction. As a result, the medium to be transported is easily drawn into the press-contact portion, and the transported medium is reliably held by the pair of transport rollers.

(2) Here, when the thickness of the transported medium is h, the radius of the driving roller is R, and the radius of the driven roller is r, the angle β is a positive minimum solution of the following equation: It is desirable. By calculating the angle β using such a calculation formula, the inclination angle α can be easily determined.

  (3) The biasing means applies a biasing force in a direction opposite to the retracting direction of the driven roller. Accordingly, since all the applied urging force works as a pressing force against the driving roller, the loss of the urging force is reduced.

  (4) Further, the drive roller is stopped or reversely rotated for a predetermined time when the leading end of the transported medium reaches the pressure contact portion of the transport roller pair, and then driven again or forwardly. It is preferable. As a result, when the conveyed medium enters the pressure contact portion, the driving roller is temporarily reversed or the driving roller is continuously stopped. Therefore, for example, even when the transported medium is fed in the skew state, the skew is corrected by the driving roller and the driven roller. The present invention is suitable for a sheet conveying apparatus in which such driving roller control is performed.

  (5) The present invention may be an image recording apparatus including the sheet conveying apparatus and an image recording unit that records an image on a sheet-like conveyed medium conveyed by the sheet conveying apparatus.

  (6) Further, the present invention is suitable as long as it is an image recording apparatus provided with an image recording means for recording an image by ejecting fine ink droplets onto a transported medium.

  According to the present invention, since the inclination angle α is set larger than the angle β, the driven roller is moved by the pressure contact force and the reaction force acting on the transported medium when the transported medium is sandwiched between the transport roller pair. A rotational force is generated in the direction of forward rotation. As a result, the medium to be transported is easily drawn into the pressure contact portion, and the medium to be transported is reliably held by the pair of transport rollers. As a result, the skew of the transported medium after the start of transport is reduced, and the variation in the cue amount for each transported medium becomes uniform.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. In addition, this embodiment is only an example of this invention, and it cannot be overemphasized that embodiment can be changed suitably in the range which does not change the summary of this invention.

  FIG. 1 shows an external configuration of a multifunction machine 1 according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the internal configuration of the multifunction machine 1. The multi-function device 1 is a multi-function device (MFD) having a printer unit 2 at the bottom and a scanner unit 3 at the top, and has a printer function, a scanner function, a copy function, and a facsimile function. The printer unit 2 of the multifunction device 1 corresponds to the image recording apparatus according to the present invention. Therefore, functions other than the printer function are arbitrary. For example, the image recording apparatus according to the present invention may be implemented as a single-function printer that does not have the scanner unit 3 and has no scanner function or copy function.

  The printer unit 2 of the multifunction device 1 is connected mainly to an external information device such as a computer, and records images and documents on recording paper based on print data including image data and document data transmitted from the computer. To do. Note that the multifunction device 1 is connected to a digital camera or the like, and records image data output from the digital camera or the like on a recording paper, or is loaded with various storage media such as a memory card and recorded on the storage medium. It is also possible to record the image data and the like on the recording paper.

  As shown in FIG. 1, the multifunction device 1 has a wide, thin, rectangular parallelepiped outer shape whose width and depth are larger than the height, and a lower portion of the multifunction device 1 is a printer unit 2. The printer unit 2 has an opening 2a formed in the front. The paper feed tray 20 and the paper discharge tray 21 are provided in two upper and lower stages inside the opening 2a. The paper feed tray 20 stores recording paper, which is a medium to be transported, and stores recording paper of various sizes such as B5 size and postcard size, for example, A4 size or less. As shown in FIG. 2, the tray surface of the paper feed tray 20 is expanded by pulling out the slide tray 20a as necessary, and for example, a legal size recording paper can be accommodated. The recording paper stored in the paper supply tray 20 is fed into the printer unit 2 to record a desired image and discharged to the paper discharge tray 21.

  The upper part of the multifunction device 1 is a scanner unit 3, which is configured as a so-called flat bed scanner. As shown in FIGS. 1 and 2, a platen glass 31 and an image sensor 32 are provided below a document cover 30 that can be opened and closed as a top plate of the multifunction machine 1. On the platen glass 31, an original for reading an image is placed. Below the platen glass 31, an image sensor 32 whose main scanning direction is the depth direction of the multifunction device 1 (left and right direction in FIG. 2) can reciprocate in the width direction of the multifunction device 1 (perpendicular to the paper surface in FIG. 2). Is provided.

  An operation panel 4 for operating the printer unit 2 and the scanner unit 3 is provided in the upper front portion of the multifunction machine 1. The operation panel 4 includes various operation buttons and a liquid crystal display unit. The multifunction device 1 operates based on an operation instruction from the operation panel 4. When the multifunction device 1 is connected to an external computer, the multifunction device 1 also operates based on an instruction transmitted from the computer via a printer driver or a scanner driver. A slot portion 5 is provided in the upper left part of the front surface of the multifunction machine 1. The slot unit 5 can be loaded with various small memory cards as storage media. By performing a predetermined operation on the operation panel 4, the image data stored in the small memory card loaded in the slot unit 5 is read out. Information about the read image data is displayed on the liquid crystal display unit of the operation panel 4, and an arbitrary image can be recorded on the recording paper by the printer unit 2 based on this display.

  Hereinafter, the internal configuration of the multi-function device 1, particularly the configuration of the printer unit 2 will be described with reference to FIGS. 1 to 5. As shown in FIG. 2, a paper feed tray 20 is provided on the bottom side of the multifunction machine 1, and a separation inclined plate 22 is provided on the back side of the paper feed tray 20. The separation inclined plate 22 separates the recording paper that has been multi-fed from the paper feed tray 20 and guides the uppermost recording paper upward. The sheet conveyance path 23 is directed upward from the separation inclined plate 22, then bends to the front side, extends from the back side to the front side of the multifunction machine 1, and is discharged through the image recording unit 24 (an example of image recording means). It leads to the paper tray 21. Accordingly, the recording paper stored in the paper feed tray 20 is guided by the paper conveyance path 23 so as to make a U-turn from the lower side to the upper side, reaches the image recording unit 24, and after image recording is performed by the image recording unit 24. The paper is discharged to the paper discharge tray 21.

  FIG. 3 is a partial enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 4 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. As shown in FIG. 3, on the upper side of the paper feed tray 20, a paper feed roller 25 that supplies recording paper stacked on the paper feed tray 20 to the paper transport path 23 is provided. The paper feed roller 25 is pivotally supported at the tip of the paper feed arm 26. The paper feed roller 25 is rotated by the drive transmission mechanism 27 in which a plurality of gears are engaged with each other, with the drive of the LF motor 71 (see FIG. 6) being transmitted.

  The paper feed arm 26 is arranged with a base shaft 26 a as a rotation shaft, and moves up and down so as to be able to contact and separate from the paper feed tray 20. As shown in FIG. 3, the paper feed arm 26 is rotated downward so as to come into contact with the paper feed tray 20 by its own weight or biased by a spring or the like. It is configured to be retractable upward. As the paper feeding arm 26 is rotated downward, the paper feeding roller 25 pivotally supported at the tip thereof presses against the recording paper on the paper feeding tray 20. In this state, when the paper feed roller 25 is rotated, the uppermost recording paper is fed out to the separation inclined plate 22 by the frictional force between the roller surface of the paper feeding roller 25 and the recording paper. The leading edge of the recording paper abuts against the separation inclined plate 22 and is guided upward, and is fed into the paper conveyance path 23. When the uppermost recording paper is sent out by the paper supply roller 25, the recording paper immediately below the recording paper may be sent out together due to friction or static electricity. However, the recording paper is restrained by contact with the separation inclined plate 22. Is done.

  The sheet conveyance path 23 is configured by an outer guide surface and an inner guide surface that are opposed to each other at a predetermined interval, except for a portion where the image recording unit 24 and the like are disposed. For example, the curved portion 17 of the sheet conveyance path 23 on the back side of the multifunction machine 1 is configured by fixing an outer guide member 18 and an inner guide member 19 to the apparatus frame. In the sheet conveyance path 23, particularly at a position where the sheet conveyance path 23 is bent, the roller surface is exposed to the outer guide surface so that the roller 16 is exposed to the outer guide surface, and the width direction of the sheet conveyance path 23 is axially rotatable. Is provided. The recording paper that is slidably in contact with the guide surface is smoothly transported by the rotatable rotary rollers 16 at locations where the paper transport path 23 is bent.

  An image recording unit 24 is provided in the paper transport path 23 (see FIG. 2). As shown in FIG. 3, the image recording unit 24 includes a carriage 38 that is mounted with an ink jet recording head 39 (see FIG. 5) and reciprocates in the main scanning direction. The ink jet recording head 39 includes cyan (C), magenta (M), yellow (Y), and ink through an ink tube 41 (see FIG. 4) from an ink cartridge disposed in the multifunction device 1 independently of the ink jet recording head 39. Black (Bk) color inks are supplied. While the carriage 38 is reciprocated, each color ink is selectively ejected as fine ink droplets from the ink jet recording head 39, whereby the recording paper conveyed on the mounting surface 42a (see FIG. 11) of the platen 42. Image recording is performed. 3 and 4 do not show the ink cartridge.

  FIG. 4 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. FIG. 5 is a perspective view showing a mechanism in the vicinity of the image recording unit 24. In FIG. 5, the ink tube 41 and the flat cable 85 are omitted. As shown in FIGS. 4 and 5, a pair of guide rails 43 and 44 are separated from each other by a predetermined distance in the recording paper conveyance direction (from the upper side to the lower side in FIG. 4) on the upper side of the paper conveyance path 23. Is extended in a direction (left-right direction in FIG. 4) perpendicular to the conveying direction. The guide rails 43 and 44 are provided in the casing of the printer unit 2 and constitute a part of a frame that supports each member constituting the printer unit 2. The carriage 38 is placed so as to be slidable in a direction orthogonal to the recording paper conveyance direction so as to straddle the guide rails 43 and 44. As described above, the guide rails 43 and 44 are arranged almost horizontally in the recording paper conveyance direction, so that the height of the printer unit 2 is reduced and the apparatus is thinned.

  The guide rail 43 disposed on the upstream side of the recording paper conveyance direction is a flat plate whose length in the width direction (left-right direction in FIG. 4) of the paper conveyance path 23 is longer than the reciprocating range of the carriage 38. The guide rail 44 disposed on the downstream side in the recording paper conveyance direction is a flat plate whose length in the width direction of the paper conveyance path 23 is substantially the same as that of the guide rail 43. The upstream end of the carriage 38 in the transport direction is placed on the guide rail 43, and the downstream end of the carriage 38 in the transport direction is placed on the guide rail 44, and the carriage 38 extends in the longitudinal direction of the guide rails 43, 44. Is slid. The edge 45 on the upstream side in the transport direction of the guide rail 44 is bent at a substantially right angle upward. The carriage 38 carried on the guide rails 43 and 44 slidably holds the edge 45 by a holding member such as a roller pair. As a result, the carriage 38 is positioned with respect to the recording paper transport direction and can slide in a direction orthogonal to the recording paper transport direction. That is, the carriage 38 is slidably supported on the guide rails 43 and 44 and reciprocates in a direction perpendicular to the recording paper conveyance direction with the edge 45 of the guide rail 44 as a reference. Although not shown in the drawing, a lubricant such as grease is applied to the edge 45 in order to make the carriage 38 slide smoothly.

  A belt drive mechanism 46 is disposed on the upper surface of the guide rail 44. In the belt driving mechanism 46, an endless annular timing belt 49 having teeth on the inside is stretched between a driving pulley 47 and a driven pulley 48 provided near both ends in the width direction of the paper conveyance path 23. It will be. A driving force is input from the CR motor 73 (see FIG. 5) to the shaft of the driving pulley 47, and the timing belt 49 moves circumferentially as the driving pulley 47 rotates. In addition to the endless annular belt, the timing belt 49 may be one that fixes both ends of the endless belt to the carriage 38.

  The carriage 38 is fixed to the timing belt 49 on the bottom surface side. Therefore, based on the circumferential motion of the timing belt 49, the carriage 38 reciprocates on the guide rails 43 and 44 with the edge 45 as a reference. An ink jet recording head 39 is mounted on such a carriage 38, and the ink jet recording head 39 is reciprocated with the width direction of the paper transport path 23 as the main scanning direction.

  The guide rail 44 is provided with an encoder strip 50 of a linear encoder 77 (see FIG. 6). The encoder strip 50 is in the form of a strip made of a transparent resin. A pair of support portions 33 and 34 are formed at both ends of the guide rail 44 in the width direction (reciprocating direction of the carriage 38) so as to stand up from the upper surface thereof. Both ends of the encoder strip 50 are engaged with the support portions 33 and 34, and are erected along the edge 45. Although not shown in the drawing, a leaf spring is provided on one of the support portions 33 and 34, and the end portion of the encoder strip 50 is locked by the leaf spring. This leaf spring prevents tension from acting on the encoder strip 50 in the longitudinal direction to cause slack, and when an external force acts on the encoder strip 50, the leaf spring elastically deforms, The encoder strip 50 is bent.

  The encoder strip 50 has a pattern in which light-transmitting portions that transmit light and light-shielding portions that block light are alternately arranged at a predetermined pitch in the longitudinal direction. An optical sensor 35 that is a transmission type sensor is provided at a position corresponding to the encoder strip 50 on the upper surface of the carriage 38. The optical sensor 35 reciprocates along the longitudinal direction of the encoder strip 50 together with the carriage 38, and detects the pattern of the encoder strip 50 during the reciprocation. The ink jet recording head 39 is provided with a head control substrate that controls ink ejection. The head control board outputs a pulse signal based on the detection signal of the optical sensor 35, the position of the carriage 38 is determined based on the pulse signal, and the reciprocation of the carriage 38 is controlled. 4 and 5, the head control board is covered with the head cover of the carriage 38 and is not shown in the drawings.

  As shown in FIGS. 4 and 5, a platen 42 is disposed below the paper transport path 23 so as to face the ink jet recording head 39. The platen 42 is disposed over the central portion of the reciprocating range of the carriage 38 through which the recording paper passes. The width of the platen 42 is sufficiently larger than the maximum width of the recording paper that can be conveyed, and both ends of the recording paper always pass over the platen 42. The platen 42 is disposed such that its placement surface 42a (see FIG. 11) is parallel to the installation surface of the multifunction machine 1.

  As shown in FIGS. 4 and 5, maintenance units such as a purge mechanism 51 and a waste ink tray 84 are disposed outside the range where the recording paper does not pass, that is, outside the image recording range by the ink jet recording head 39. The purge mechanism 51 sucks and removes bubbles and foreign matters from the nozzles of the ink jet recording head 39. The nozzle is not shown in the figure. The purge mechanism 51 includes a cap 52 that covers the nozzles of the ink jet recording head 39, a pump mechanism that is connected to the ink jet recording head 39 through the cap 52, and a moving mechanism that moves the cap 52 to and away from the nozzles of the ink jet recording head 39. Consists of. 4 and 5, the pump mechanism and the moving mechanism are below the guide frame 44 and are not shown in the drawings. When sucking and removing bubbles or the like from the inkjet recording head 39, the carriage 38 is moved so that the inkjet recording head 39 is positioned on the cap 52. In this state, the cap 52 is moved upward and is in close contact with the lower surface of the inkjet recording head 39 so as to seal the nozzle. By making the pressure in the cap 52 negative by the pump mechanism, ink is sucked from the nozzles of the inkjet recording head 39. Bubbles and foreign matter in the nozzle are sucked and removed together with the ink.

  The waste ink tray 84 is for receiving idle ink discharge from the inkjet recording head 39 called flushing. The waste ink tray 84 is formed on the upper surface of the platen 42 and within the reciprocating range of the carriage 38 and outside the image recording range. A felt is laid in the waste ink tray 84, and the flushed ink is absorbed and held by the felt. These maintenance units perform maintenance such as removal of air bubbles and mixed color ink in the ink jet recording head 39 and prevention of drying.

  As shown in FIG. 1, a door 7 is provided on the front surface of the casing of the printer unit 2 so as to be freely opened and closed. When the door 7 is opened, the cartridge mounting portion is exposed to the front side of the apparatus, and the ink cartridge can be removed. Although not shown in the drawing, the cartridge mounting portion is divided into four storage chambers corresponding to the ink cartridges, and each storage chamber stores an ink cartridge for holding each color ink of cyan, magenta, yellow, and black. The As shown in FIG. 4, four ink tubes 41 corresponding to the respective color inks are routed from the cartridge mounting portion to the carriage 38. The ink-jet recording head 39 mounted on the carriage 38 is supplied with ink of each color from the ink cartridge mounted on the cartridge mounting portion through each ink tube 41.

  The ink tube 41 is a tube made of synthetic resin, and has flexibility to bend following the reciprocation of the carriage 38. Each ink tube 41 led out from the cartridge mounting portion is pulled out to the vicinity of the center along the width direction of the apparatus, and is temporarily fixed to the fixing clip 36 of the apparatus main body. The portions of the ink tubes 41 from the fixed clip 36 to the carriage 38 are not fixed to the apparatus main body or the like, and the portions change their postures following the reciprocation of the carriage 38. In FIG. 4, the ink tube 41 extending from the fixed clip 36 toward the cartridge mounting portion is omitted.

  As shown in FIG. 4, the ink tube 41 is drawn by forming a curved portion where the portion from the fixed clip 36 to the carriage 38 is reversed in the reciprocating direction of the carriage 38. In other words, the ink tube 41 is routed so as to form a substantially U shape in plan view. The four ink tubes 41 are arranged in the horizontal direction along the recording paper conveyance direction in the carriage 38, and extend in the reciprocating direction of the carriage 38. On the other hand, in the fixed clip 36, four ink tubes 41 are arranged and fixed in a state of being stacked in the vertical direction. The fixed clip 36 is a member having a U-shaped cross section that opens upward, and the four ink tubes 41 that are stacked in the vertical direction with the ink tubes 41 inserted through the openings are integrated by the fixed clip 36. It is pinched. As a result, the four ink tubes 41 are bent into a substantially U shape as a whole while being twisted so that the horizontal arrangement becomes the vertical arrangement from the carriage 38 toward the fixed clip 36. Yes.

  The four ink tubes 41 have substantially the same length from the carriage 38 to the fixed clip 36. In the carriage 38, the ink tube 41 arranged on the most upstream side in the recording paper conveyance direction is arranged on the uppermost side in the fixed clip 36. The ink tube 41 disposed upstream of the ink tube 41 is disposed below the ink tube 41 in the fixing clip 36. By repeating this, the fixing clip 36 is sequentially arranged from the uppermost side to the lower side in order from the upstream side ink tube 41 in the recording paper conveyance direction in the carriage 38 toward the downstream side in the conveyance direction. Since the length of each ink tube 41 is substantially the same, the center of the substantially U-shaped curved portion of each ink tube 41 is curved so as to be shifted in the recording paper conveyance direction according to the arrangement of the carriage 38 in the recording paper conveyance direction. Thereby, in the curved portion, the four ink tubes 41 are aligned in an oblique direction from the upper side to the lower side, and interference between the ink tubes 41 when the posture changes following the carriage 38 is reduced. The In the present embodiment, four ink tubes 41 are shown. However, when the number of ink tubes 41 further increases, the ink tubes 41 on the upstream side in the recording paper conveyance direction in the carriage 38 are sequentially sequentially changed. They are sequentially arranged on the upper side of the fixed clip 36.

  A recording signal or the like is transmitted through the flat cable 85 from the main substrate constituting the control unit 64 (see FIG. 6) to the head control substrate of the ink jet recording head 39. The main board is disposed on the front side of the apparatus (front side in FIG. 4) and is not shown in FIG. The flat cable 85 is a ribbon-shaped cable in which a plurality of conductive wires that transmit electrical signals are covered with a synthetic resin film such as a polyester film and insulated, and electrically connects the main board and the head control board. .

  The flat cable 85 has flexibility to bend following the reciprocation of the carriage 38. As shown in FIG. 4, the flat cable 85 is routed by forming a curved portion where the portion from the carriage 38 to the fixed clip 86 is reversed in the reciprocating direction of the carriage 38. In other words, the flat cable 85 is routed so as to form a substantially U-shape in plan view with the strip-shaped front and back surfaces in the vertical direction. That is, on the front and back surfaces of the flat cable 85, the vertical line is oriented in the horizontal direction and the surface is spread in the vertical direction. The direction in which the flat cable 85 extends from the carriage 38 and the direction in which the ink tube 41 extends are the same as the reciprocating direction of the carriage 38.

  One end side of the flat cable 85 fixed to the carriage 38 is electrically connected to a head control board mounted on the carriage 38. The other end side of the flat cable 85 fixed to the fixing clip 86 is further extended and electrically connected to the main board. The portion where the flat cable 85 is bent in a substantially U shape is not fixed to any member, and changes its posture following the reciprocation of the carriage 38, as with the ink tube 41. As described above, the ink tube 41 and the flat cable 85 that change in posture following the reciprocating motion of the carriage 38 are supported by the rotation support member 100.

  On the apparatus front side of the ink tube 41 and the flat cable 85, a restriction wall 37 is extended in the apparatus width direction (left-right direction in FIG. 4). The restriction wall 37 is a wall having a vertical wall surface that abuts on the ink tube 41, and is erected in a straight line along the reciprocating direction of the carriage 38. The restriction wall 37 is provided in the extending direction of the ink tube 41 from the fixed clip 36 that fixes the ink tube 41, and all of the four ink tubes 41 arranged in the vertical direction by the fixed clip 36 can contact each other. Height.

  The ink tube 41 extends from the fixed clip 36 along the restriction wall 37, and swells in the direction away from the carriage 38 in other words, by contacting the wall of the restriction wall 37 on the apparatus rear side. It is regulated to be released. In a state in which the ink tube 41 is in contact with the regulation wall 37, the portion from the fixed clip 36 to the curved portion of the ink tube 41 is maintained in the vertical arrangement in the fixed clip 36. In the curved portion, the ink tube 41 is reliably maintained in a desired oblique arrangement.

  The fixing clip 36 is provided near the approximate center in the width direction of the apparatus, and fixes the ink tube 41 so as to extend toward the regulation wall 37. That is, the vertical wall surface of the restriction wall 37 and the direction in which the fixing clip 36 extends the ink tube 41 form an obtuse angle smaller than 180 ° in plan view. The ink tube 41 has flexibility, but also has an appropriate waist (bending rigidity). Therefore, the ink tube 41 is extended with an angle with respect to the regulation wall 37 by the fixing clip 36, so that the wall of the regulation wall 37 is formed. Pressed. As a result, in the reciprocating range of the carriage 38, the range in which the ink tube 41 can be moved along the restriction wall 37 increases, and the portion from the curved portion of the ink tube 41 to the carriage 38 is the rear side of the apparatus, in other words, the carriage. The range that bulges to the 38 side can be reduced.

  The fixing clip 86 is provided at a position near the center in the width direction of the apparatus and on the curved inner side of the fixing clip 36, and fixes the flat cable 85 so as to extend toward the regulation wall 37. . That is, the vertical wall surface of the regulating wall 37 and the direction in which the fixing clip 86 extends the flat cable 85 form an obtuse angle smaller than 180 ° in plan view. The flat cable 85 has flexibility, but also has an appropriate waist (bending rigidity). Therefore, the flat cable 85 is extended with an angle with respect to the regulation wall 37 by the fixing clip 86, so that the flat cable 85 is attached to the wall surface of the regulation wall 37. Pressed. Thereby, in the reciprocating range of the carriage 38, the range in which the flat cable 85 can be moved along the restriction wall 37 increases, and the portion from the curved portion of the flat cable 85 to the carriage 38 is the rear side of the apparatus, in other words, the carriage. The range that bulges to the 38 side can be reduced.

  As shown in FIGS. 3 and 5, on the upstream side in the transport direction of the image recording unit 24, there are a driving roller 87 and a pinch roller 88 (corresponding to a driven roller) disposed in a pressed state below the driving roller 87. A pair of conveying rollers 89 having the above is provided. The sheet conveying apparatus of the present invention is embodied with the conveying roller body 89 as a main component. The conveyance roller pair 89 is conveyed in the paper conveyance path 23 and performs registration processing on the recording paper inserted into the press contact portion of the driving roller 87 and the pinch roller 88, and after the registration processing is performed for a predetermined time, It is sandwiched and conveyed toward the platen 42.

  The pinch roller 88 is rotatably supported by a pinch roller holder 96 (an example of support means) while being pressed against the drive roller 87 with a predetermined urging force. The pinch roller holder 96 is supported by a holder support member 97 provided integrally with an internal frame 95 (see FIG. 3) that forms the housing of the multifunction machine 1 so as to be able to roll in the recording paper conveyance direction. By adopting such a support structure, when conveyance of the recording paper by the conveyance roller pair 89 is started, the pinch roller holder 96 moves while rolling to the conveyance position on the downstream side in the conveyance direction shown in FIG. It is maintained in that position during paper transport. When the trailing edge of the recording paper comes out of the conveying roller pair 89, the pinch roller holder 96 immediately moves while rolling to the retracted position upstream in the conveying direction shown in FIG. The configurations of the holder support member 97 and the pinch roller holder 96 and the support structure for supporting the pinch roller holder 96 by the holder support member 97 will be described in detail later.

  As shown in FIG. 3, a pair of discharge rollers 92 having a driving roller 90 and a spur roller 91 provided above the driving roller 90 is provided on the downstream side in the transport direction of the image recording unit 24. . The driving roller 90 and the spur roller 91 sandwich the recorded recording paper and convey it to the paper discharge tray 21. Since the spur roller 91 is in pressure contact with the recorded recording paper, the roller surface is uneven in a spur shape so as not to deteriorate the image recorded on the recording paper. The spur roller 91 is provided so as to be slidable in a direction in which the spur roller 91 contacts and separates from the drive roller 90, and is urged so as to be in pressure contact with the drive roller 90 by a coil spring (not shown). When the recording paper enters between the driving roller 90 and the spur roller 91, the spur roller 91 retreats against the urging force by the thickness of the recording paper and pinches the recording paper so as to be in pressure contact with the driving roller 90. . Thereby, the rotational force of the drive roller 90 is reliably transmitted to the recording paper.

  The driving rollers 87 and 90 are rotationally driven by a driving force transmitted from an LF motor 71 (see FIG. 6) connected to one end of the driving roller 87 in the axial direction. When the recording paper fed from the paper feed tray 20 enters the pressure contact portion between the driving roller 87 and the pinch roller 88, the driving roller is rotated (reversely driven) in a direction to return the recording paper to the upstream side in the transport direction. The leading edge of the recording paper that has reached the press contact portion is subjected to registration processing by the pin 87 and the pinch roller 88 that follows it, and the skew of the recording paper is corrected. The registration process can also be realized by stopping the driving roller 87 without driving it in the reverse direction.

  When the registration process is performed for a predetermined time, the driving roller 87 is rotationally driven (forward rotation driving) in a direction in which the recording paper is conveyed downstream in the conveying direction. As a result, the recording paper is nipped and conveyed downstream in the conveyance direction. The rotations of the drive rollers 87 and 90 are synchronized. The pattern of the encoder disk 93 that rotates together with the drive roller 87 is detected by the optical sensor 94 by a rotary encoder 76 (see FIG. 6) provided on the drive roller 87. Based on this detection signal, the rotation of the drive rollers 87 and 90 is controlled by the control unit 64 (see FIG. 6).

  The drive roller 87 is intermittently driven with a predetermined line feed width. Accordingly, the recording paper sandwiched between the driving roller 87 and the pinch roller 88 is intermittently conveyed on the platen 42 with a predetermined line feed width. The ink jet recording head 39 is scanned for each line feed, and image recording is performed from the leading end side of the recording paper. The leading end side of the recording paper on which image recording has been performed is sandwiched between a driving roller 90 and a spur roller 91. That is, the recording paper is intermittently conveyed with a predetermined line feed width with the leading end side sandwiched between the driving roller 90 and the spur roller 91 and the trailing end side sandwiched between the driving roller 87 and the pinch roller 88. In addition, image recording is performed by the ink jet recording head 39. When the recording paper is further transported, the trailing edge of the recording paper comes out of the driving roller 87 and the pinch roller 88 and is released from the nipping by the transport roller pair 89. That is, the recording paper is sandwiched only by the drive roller 90 and the spur roller 91 and is intermittently conveyed with a predetermined line feed width, and image recording is performed by the ink jet recording head 39 for each line feed. After image recording is performed on a predetermined area of the recording paper, the driving roller 90 is continuously rotated. As a result, the recording paper sandwiched between the driving roller 90 and the spur roller 91 is discharged to the paper discharge tray 21.

  FIG. 6 is a block diagram illustrating a configuration of the control unit 64 of the multifunction machine 1. The control unit 64 controls the overall operation of the multifunction machine 1 including not only the printer unit 3 but also the scanner unit 2, and is configured by a main board to which a flat cable 85 is connected. Since the configuration relating to the scanner unit 3 is not the main configuration of the present invention, detailed description thereof is omitted. As shown in the figure, the control unit 64 is a microcomputer mainly including a CPU (Central Processing Unit) 65, a ROM (Read Only Memory) 66, a RAM (Random Access Memory) 67, and an EEPROM (Electrically Erasable and Programmable ROM) 68. And is connected to an ASIC (Application Specific Integrated Circuit) 70 via a bus 69.

  The ROM 66 stores programs for controlling various operations of the multifunction machine 1. The RAM 67 is used as a storage area or a work area for temporarily recording various data used when the CPU 65 executes the program. The EEPROM 68 stores settings and flags that should be retained even after the power is turned off.

  The ASIC 70 generates a phase excitation signal and the like for energizing the LF (conveyance) motor 71 in accordance with a command from the CPU 65, applies the signal to the drive circuit 72 of the LF motor 71, and sends the drive signal via the drive circuit 72. By energizing the LF motor 71, the rotation of the LF motor 71 is controlled.

  The drive circuit 72 drives the LF motor 71 connected to the paper feed roller 25, the drive rollers 87 and 90, and the purge mechanism 51. The drive circuit 72 receives the output signal from the ASIC 70 and rotates the LF motor 71. The electrical signal is formed. In response to the electrical signal, the LF motor 71 rotates, and the rotational force of the LF motor 71 is fed via a known drive mechanism including a gear, a drive shaft, and the like, and the feed roller 25, drive rollers 87 and 90, and the purge mechanism 51. Is transmitted to.

  The ASIC 70 generates a phase excitation signal and the like for energizing a CR (carriage) motor 73 in accordance with a command from the CPU 65, applies the signal to the drive circuit 74 of the CR motor 73, and sends the drive signal via the drive circuit 74. By energizing the CR motor 73, rotation control of the CR motor 73 is performed.

  The drive circuit 74 drives the CR motor 73, receives an output signal from the ASIC 70, and forms an electric signal for rotating the CR motor 73. The CR motor 73 rotates in response to the electric signal, and the rotational force of the CR motor 73 is transmitted to the carriage 38 via the belt drive mechanism 46, whereby the carriage 38 is reciprocated. In this way, the reciprocation of the carriage 38 is controlled by the control unit 64.

  The drive circuit 75 selectively ejects each color ink onto the recording paper at a predetermined timing from the ink jet recording head 39, and outputs an output signal generated in the ASIC 70 based on a drive control procedure output from the CPU 65. The ink jet recording head 39 is driven and controlled. The drive circuit 75 is mounted on the head control board, and a signal is transmitted by a flat cable 85 from the main board constituting the control unit 64 to the head control board.

  Connected to the ASIC 70 are a rotary encoder 76 that detects the amount of rotation of the drive roller 87 and a linear encoder 77 that detects the position of the carriage 38. The carriage 38 is moved to one end of the guide rails 43 and 44 when the power of the multifunction machine 1 is turned on, and the detection position by the linear encoder 77 is initialized. When the carriage 38 moves on the guide rails 43 and 44 from this initial position, the optical sensor 35 provided on the carriage 38 detects the pattern of the encoder strip 50, and the number of pulse signals based on this detects the amount of movement of the carriage 38. It is grasped by the control unit 64. The controller 64 controls the rotation of the CR motor 73 so as to control the reciprocation of the carriage 38 based on the amount of movement.

  The ASIC 70 includes a scanner unit 3, an operation panel 4 for instructing operation of the multifunction device 1, a slot unit 5 into which various small memory cards are inserted, an external information device such as a personal computer, and a parallel cable or a USB cable. A parallel interface 78 and a USB interface 79 for transmitting and receiving data are connected. Further, an NCU (Network Control Unit) 80 and a modem (MODEM) 81 for realizing the facsimile function are connected.

  Next, the configuration of the holder support member 97 and the pinch roller holder 96 and the support structure of the pinch roller holder 96 will be described in detail with reference to FIGS. 7 is a perspective view showing a state in which the pinch roller holder 96 is supported by the holder support member 97, FIG. 8 is an exploded view of the holder support member 97 and the pinch roller holder 96, and FIG. 9 shows the configuration of the rolling bearing 125. FIG. 10 is a partially enlarged view for explaining the movement range of the pinch roller holder 96, and FIGS. 11 to 13 are schematic sectional views showing the positional relationship between the drive roller 87 and the pinch roller 88. 11 to 13, the thickness h of the recording paper S is exaggerated for easy explanation.

  The pinch roller holder 96 is formed in a long shape as shown in FIGS. 7 and 8, and is arranged so that the longitudinal direction thereof coincides with the width direction of the recording paper. Four roller accommodating chambers 98 and eight spring accommodating chambers 99 are provided on the upper surface of the pinch roller holder 96 facing the drive roller 87. The roller accommodating chamber 98 is formed at predetermined intervals in the longitudinal direction of the pinch roller holder 96. The pinch roller 88 is accommodated in the roller accommodating chamber 98 so that the rotation shaft 130 of the pinch roller holder 96 coincides with the longitudinal direction of the pinch roller holder 96. The spring accommodating chamber 99 is formed adjacent to both ends of the roller accommodating chamber 98. A coil spring 131 (an example of an urging means) is accommodated in the spring accommodating chamber 99 in a compressed state. Needless to say, the number of pinch rollers 88 and coil springs 131 and the accommodation method can be appropriately changed.

  The spring accommodating chamber 99 is partitioned by partition plates 132 provided upright on both sides in the longitudinal direction of the spring accommodating chamber 99. A bearing 133 is formed on the partition plate 132. The pivot shaft 130 of the pinch roller 88 is supported by a bearing 133. The bearing 133 is formed in a groove shape long in the depth direction of the roller accommodating chamber 98. The upper end portion of the groove of the bearing 133 is formed to be slightly smaller than the shaft diameter of the rotating shaft 130, and when the rotating shaft 130 is pushed into the bearing 133, the upper end portion of the groove is bent and widened, so that the rotating shaft 130. Insertion is accepted. Further, when the rotating shaft 130 is completely inserted, the upper end portion of the groove returns to the original shape, and is supported so that the rotating shaft 130 is not easily detached. Thereby, the rotating shaft 130 is pivotally supported by the bearing 133 so as to be vertically movable in the depth direction of the groove of the bearing 133. That is, the pinch roller 88 is pivotally supported in the depth direction of the groove of the bearing 133 so as to be movable up and down.

  The spring accommodating chamber 99 is formed in a concave shape in the same direction as the depth direction of the groove of the bearing 133 formed in the partition plate 132. The coil spring 131 is accommodated in the spring accommodating chamber 99, and the rotating shaft 130 of the pinch roller 88 is inserted into the bearing 133, so that the coil spring 131 is attached to the spring accommodating chamber 99 in a compressed state. As a result, the spring force of the compressed coil spring 131 acts to push the pinch roller 88 upward. That is, a pressure contact force against the driving roller 87 is applied to the pinch roller 88. Since the pinch roller 88 is urged by the coil spring 131 and supported by the bearing 133 in this way, when a recording sheet having a predetermined thickness is conveyed, the pinch roller 88 is pinched against the urging force of the coil spring 131 according to the sheet thickness. Roller 88 descends.

  As described above, the spring accommodating chamber 99 is formed in a concave shape in the same direction as the depth direction of the groove of the bearing 133. Therefore, the extending direction of the coil spring 131 coincides with the vertical movement direction of the pinch roller 88. As a result, all the urging force of the coil spring 131 is applied to the pinch roller 88 as a pressing force against the drive roller 87. Of course, if the mechanism is such that the pressure contact force to the drive roller 87 is applied to the pinch roller 88, the extension direction of the coil spring 131 and the vertical movement direction of the pinch roller 88 do not have to coincide with each other. Various springs such as a leaf spring can be applied as the coil spring 131. Further, any biasing means may be employed as long as it applies the pressure contact force to the pinch roller 88, and for example, an elastic member such as rubber can be applied.

  On the bottom surface of the pinch roller holder 96, four projecting pieces 135 are formed that engage with the four engaging grooves 134 (see FIG. 8) formed in the holder support member 97. The projecting piece 135 is a flat plate-like member that projects downward from the bottom surface of the pinch roller holder 96 and extends in the short direction of the pinch roller holder 96. By inserting the protruding piece 135 into the engaging groove 134, the protruding piece 135 is fitted into the engaging groove 134 with a predetermined play. In this state, the pinch roller holder 96 is supported by the holder support member 97 so as to be movable in the short direction of the holder support member 97, that is, in the recording paper transport direction, and the movement range is restricted within a predetermined range. .

  The holder support member 97 is formed in a long shape like the pinch roller holder 96, and is disposed in the inner frame 95 (see FIG. 3) so that the longitudinal direction thereof coincides with the width direction of the recording paper. Specifically, as shown in FIG. 3, the protrusion 140 formed on the bottom surface of the holder support member 97 is positioned and fixed to the inner frame 95 by being fitted into a hole (not shown) of the inner frame 95. A curved surface 136 is formed on the upper surface of the holder support member 97 as shown in FIG. The pinch roller holder 96 is supported from the bottom surface with the rolling bearing 125 interposed on the curved surface 136.

  As shown in FIG. 10, the curved surface 136 of the holder support member 97 is inclined downward from the upstream side in the transport direction toward the downstream side in the transport direction on the curved surface 136. The curved surface 136 is formed in a shape substantially coinciding with a cylindrical outer peripheral arc drawn around a revolution axis passing through a point O (hereinafter referred to as “revolution center point O”) shown in FIG. The revolution axis is set parallel to the rotation axis of the drive roller 87 (axis passing through the point A in the figure) and vertically above the rotation axis. Therefore, the rotation axis of the driving roller 87 and the revolution axis are included in the same vertical plane. The pinch roller holder 96 rolls and moves about the revolution axis passing through the revolution center point O by rolling and moving along the curved surface 136. At this time, since the pinch roller 88 is urged by the coil spring 131, the pinch roller 88 moves along the outer peripheral surface of the drive roller 87 while keeping the pressure contact with the drive roller 87 at all times. The revolution center point O is longer in the sectional distance between the revolution center point O and the curved surface 136 than in the sectional view between the point B serving as the rotation center of the pinch roller 88 and the curved surface 136. It is sufficient if it is set to a position.

  As shown in FIGS. 8 and 9, the rolling bearing 125 supports two rollers 126 arranged in tandem in the short direction of the holder support member 97 and these two rollers 126 so as to be integrally rotatable. And a roller support member 127. The roller support member 127 is attached on the curved surface 136 on the upper surface of the holder support member 97 while supporting the roller 126. Specifically, the engaging claws 128 having an L-shaped cross section formed on the roller support member 127 are engaged with four sets of engaged portions 137 (see FIG. 8) formed on the curved surface 136. It is attached by. As shown in the figure, four rolling bearings 125 are attached at predetermined intervals in the longitudinal direction of the holder support member 97. By supporting the pinch roller holder 96 with the rolling bearing 125 thus configured interposed on the curved surface 136 of the holder support member 97, the pinch roller holder 96 is supported so as to be able to roll. In the present embodiment, an example in which the rolling bearing 125 is used as a configuration that supports the pinch roller holder 96 so as to be able to roll is described. For example, instead of the rolling bearing 125, the curved surface 136 or the holder support member 97 It is also possible to adopt a configuration in which a rotating body is integrally provided on the bottom surface of the pinch roller holder 96 so as to be rotatable. For example, it is conceivable to incorporate a known roller bearing or ball bearing on the curved surface 136 or the bottom surface.

  On the curved surface 136 on the upper surface of the holder support member 97, four engagement grooves 134 that engage with the protruding pieces 135 are formed. The length of the engagement groove 134 in the short direction of the pinch roller holder 96 is formed sufficiently longer than the extended length of the protruding piece 135 in the short direction. A rib 138 extending further upward from the curved surface 136 of the holder support member 97 is formed at the rear end of the engagement groove 134 so as to continue upward from the inner wall on the rear side of the engagement groove 134. Yes. The rib 138 is for restricting rearward movement of the pinch roller holder 96. When the pinch roller holder 96 is supported by the holder support member 97 so as to be movable in the short direction with the protruding piece 135 engaged with the engaging groove 134, the front end of the protruding piece 135 and the front of the engaging groove 134 are supported. The forward movement of the pinch roller holder 96 is restricted by the contact with the inner wall on the side, and the backward movement of the pinch roller holder 96 is restricted by the contact between the rear end of the protruding piece 135 and the rib 138. The

  In the present embodiment, as shown in FIG. 10, the range of movement of the pinch roller holder 96 in the short direction (left and right direction in FIG. 10) is based on the revolution axis (the axis passing through the revolution center point O). The angle θ formed by the shaft and the vertical plane (corresponding to the first vertical plane) passing through the rotation axis of the drive roller 87 is pinched at a position where θ1 (> 0) to the rear side (upstream side in the transport direction) of the drive roller 87. The pinch roller 88 is located at a position where the angle θ formed with the vertical plane is θ2 (> θ1) from the conveyance position where the roller 88 is positioned (first position, the position indicated by the solid line in FIG. 10, see FIG. 17). The position is limited to the retracted position to be positioned (second position, position indicated by a broken line in FIG. 10, see FIG. 16). In other words, in a sectional view, an angle θ formed by a line segment OA connecting the revolution center point O and the point A and a line segment OB connecting the revolution center point O and the point B is in a range of θ1 ≦ θ ≦ θ2. The movement of the pinch roller holder 96 in the short direction is restricted.

  By configuring the pinch roller holder 96 and the holder support member 97 as described above, when the leading edge of the recording paper is nipped by the conveyance roller pair 89 (see FIG. 3) and the conveyance is started, the pinch roller holder 96 is It is rolled from the retracted position (see FIG. 16) to the transfer position (see FIG. 17). During the conveyance of the recording paper, the pinch roller holder 96 is maintained at the conveyance position. When the trailing edge of the recording paper comes out from the conveying roller pair 89, the pinch roller holder 96 rolls to the retracted position immediately after that, and the pinch roller holder is in the retracted position during non-conveyance of the recording paper. Maintained. The rolling principle of the pinch roller holder 96 will be described in detail later.

FIG. 11 shows the positional relationship between the drive roller 87 and the pinch roller 88. In the same figure, the code | symbol D shows the said conveyance position, and the code | symbol E shows the said backward position. A point B1 in the figure is the rotation center of the pinch roller 88 when the pinch roller 88 is positioned at the transport position D, and a point B2 is the rotation of the pinch roller 88 when the pinch roller 88 is positioned at the retracted position E. It is a dynamic center. In the present embodiment, as shown in FIG. 11, when the pinch roller holder 96 is in the retracted position E in a state where the driving roller 87 and the pinch roller 88 are in pressure contact, the pinch roller 88 is The grooves are arranged so that the depth direction of the grooves coincides with a straight line L1 (indicated by a one-dot chain line) in the drawing. Accordingly, the pinch roller 88 is supported by the pinch roller holder 96 so as to be retractable from the drive roller 87 along the straight line L1. The straight line L1 passes through the point B2 in a cross-sectional view, and the rotation axis of the drive roller 87 (axis passing through the point A in the figure) and the rotation axis of the pinch roller 88 (axis passing through the point B2 in the figure). Including a first plane (corresponding to a first plane of the present invention) , that is, a preset angle α (corresponding to a predetermined inclination angle α) with respect to a first plane perpendicular to the paper surface of FIG. 11 including the line segment AB2. ) Is inclined clockwise about the point B2. In other words, the pinch roller 88 is supported so as to be retractable from the driving roller 87 at an angle α with respect to the first plane and downstream in the transport direction. As long as the pinch roller 88 is supported so as to be retractable from the driving roller 87 along the straight line L1 downstream in the conveying direction, the shapes and configurations of the pinch roller holder 96, the curved surface 136, the bearing 133, and the like are as described above. It is not limited.

Further, as shown in FIG. 12, in this embodiment, when the recording paper enters from the direction of the tangent L2 passing through the nip point P between the driving roller 87 and the pinch roller 88 toward the nip point P, the recording is performed. In the state where the corners in the thickness direction of the leading edge of the paper are in contact with the surfaces of the driving roller 87 and the pinch roller 88 at points G1 and G2, and the driving roller 87 and the pinch roller 88 are in contact at the nip point P. Is the second plane (corresponding to the second plane of the present invention) including the radius line L3 of the pinch roller 87 passing through the point G1 and the pivot axis of the pinch roller 87, and the pivot axis of the drive roller 87. The pinch roller 88 is positioned so as to be larger than an angle β formed by the first plane including the rotation axis of the pinch roller 88. That is, when the pinch roller 88 is located at the retracted position E, the angle α is set so that α> β.

  In the printer unit 2 in which the pinch roller 88 is positioned as described above, the registration process for the recording paper S is completed, and the drive roller 87 rotates clockwise in FIG. 13 in order to transport the recording paper S downstream in the transport direction. When driven, the rotational force is transmitted to the upper surface of the recording paper S, and the leading edge of the recording paper S is pushed into the nip point P. At this time, as shown in FIG. 13, since the recording paper S has a thickness h, the pinch roller 88 is retracted in the inclination direction L1 against the coil spring 131.

  At the moment when the recording paper S is sandwiched by the conveying roller pair 89, the spring force F11 of the coil spring 131 acts on the leading edge of the recording paper S as shown in FIG. Are opposite directions and the same reaction force F12 acts on the point G1 on the pinch roller 87. As shown in the figure, the reaction force F12 acts on the downstream side in the transport direction with respect to the inclination direction L1. Therefore, a rotational force F13 (component force of the reaction force F12) that rotates the pinch roller 88 counterclockwise in the drawing is generated by the spring force F11 and the reaction force F12. As a result, the corner on the lower surface side of the leading edge of the recording paper S is smoothly guided toward the nip point P by the pinch roller 88, and the leading edge of the recording paper S is securely held by the conveying roller pair 89 without slipping. As a result, the skew of the recording paper S after the resist processing is prevented, and the cueing amount to be secured at the front end of the recording paper S becomes uniform.

かかる方程式（１）を用いることによって、α＞βとなる条件を満たすための閾値となる角度βを容易に求めることができ、ピンチローラ８８の位置決めが容易となる。 The angle β is obtained by the following equation (1), where h is the recording paper thickness, R is the radius of the driving roller 87, and r is the radius of the pinch roller 88. That is, the angle α is set to be larger than the minimum positive solution of the following equation (1).

By using this equation (1), the angle β serving as a threshold for satisfying the condition of α> β can be easily obtained, and the pinch roller 88 can be easily positioned.

  Next, the rolling principle of the pinch roller holder 96 will be described with reference to FIGS. 14 and 15. FIG. 14 is a schematic diagram in which the positional relationship between the driving roller 87 and the pinch roller 88 is represented by XY coordinates with the revolution center point O as the origin in a cross-sectional view of the conveying roller pair 89, and FIG. FIG. 6 is a diagram illustrating a state in which a recording sheet (indicated by reference numeral S) is sandwiched between conveyance roller pairs 89. Also in this figure, the center of rotation of the drive roller 87 is point A, the radius is R, the center of rotation of the pinch roller 88 is point B, and the radius is r. Further, the point A is located on the Y axis, and the revolution center point O (origin O) as the origin is located at a position away from the point A in the positive direction of the Y axis by a radius R of the driving roller 87 or more. To do. The origin O coincides with the center of the arc along the curved surface 136, that is, coincides with the revolution center point O. Further, the pinch roller holder 96 is located between the transport position D advanced θ1 (> 0) from the Y axis counterclockwise around the origin O and the retracted position E similarly advanced θ2 (> θ1) from the Y axis. Can be moved by rolling. Here, the position D corresponds to the transport position described above, and the position E corresponds to the retract position described above. For convenience of description of the present invention, the revolution center point O, point A, and point B are defined as shown in FIGS. 14 and 15, but it goes without saying that the center positions of the drive roller 87, the pinch roller 88, and the curved surface, respectively. Is not limited to the positions described above.

  Now, let θ be the angle formed by the line segment OA and the line segment OB when the pinch roller 88 is moved to an arbitrary position. That is, the range that the angle θ can take is θ1 ≦ θ ≦ θ2. The pinch roller 88 is urged in the direction of the drive roller 87 (direction of line segment AB) by a coil spring 131 accommodated in a compressed state in the pinch roller holder 96.

  As shown in the figure, when θ> 0, the center point O of the arc DE and the revolution center point A of the pinch roller 88 do not coincide with each other, so that as the angle θ increases, the pinch roller holder 96 becomes the driving roller. Relative to 87. Therefore, the coil spring 131 expands as θ increases. That is, the elastic energy E of the coil spring 131 decreases as θ increases. At this time, a moment M1 having a magnitude proportional to the decrease dE / dθ of the elastic energy E acts on the pinch roller 88 in the counterclockwise direction and around the point A, that is, in the direction perpendicular to the line segment AB.

  On the other hand, the pinch roller 88 generates a frictional force (friction moment) M2 ′ around the point B in the direction opposite to the rotational direction with the driven rotation. A moment obtained by converting the frictional force M2 ′ into a force around the point A, that is, in a direction perpendicular to the line segment AB is defined as M2. The frictional force M2 ′ generated at this time is a static frictional force generated on the sliding surface between the pinch roller 88 and its rotating shaft 130 as the pinch roller 88 rotates. In FIG. 14, the moment M2 is not shown.

  Further, when the pinch roller holder 96 rolls on the curved surface 136 of the holder support member 97, a rolling friction force (friction moment) M3 ′ is generated. This rolling friction force M3 'acts around the revolution center point O, that is, in a direction perpendicular to the line segment OB. A moment obtained by converting the frictional force M3 ′ into a force around the point A, that is, in a direction perpendicular to the line segment AB is defined as M3. Here, the rolling friction force is a moment M3. In FIG. 14, the moment M3 is not shown.

  Further, when the recording paper is conveyed by the driving roller 87 and the pinch roller 88, as shown in FIG. 15, a force W such as the elastic weight due to the weight of the recording paper or the bending of the recording paper is applied to the recording paper and the pinch roller 88. It works toward the center direction (point B direction) of the pinch roller 88 from the contact point. Due to this force W, a moment M4 is generated in the direction of decreasing θ. In particular, in the present embodiment, as shown in the figure, the recording paper is conveyed from above to the platen 34 by the same angle θ as the angle formed by the line segment OA and the line segment OB, so that it is ignored. Moment M4 is generated to such an extent that it cannot be performed. Note that the rigidity of the recording paper is EI.

  Furthermore, when the leading edge of the recording paper enters the clamping portion by the driving roller 87 and the pinch roller 88, or when the trailing edge of the recording paper comes out of the clamping portion, the length of the coil spring 131 is increased by the thickness h of the recording paper. Change. Specifically, in the former case, the coil spring 131 is contracted by a thickness h, and in the latter case, the coil spring 131 is expanded by a thickness h. Accordingly, in this case as well, the elastic energy of the coil spring 131 increases and decreases, and a moment M5 around A having a magnitude proportional to dE / dθ is generated, similar to the moment M1 described above.

  Here, the angle θ (θ1 ≦ θ ≦ θ2), the recording paper thickness h, and the recording paper rigidity EI are variables. Therefore, the moment M1 can be expressed as a function of θ and h, the moment M4 can be expressed as a function of θ and EI, and the moment M5 can be expressed as a function of h. Strictly speaking, the moments M2 and M3 are functions of θ and h, but are extremely small as compared to the moments M1, M4, and M5, and therefore are regarded as constants. In the following, the function of the angle θ is expressed as M1 (θ) and M4 (θ).

  This embodiment assumes that no slip occurs between the driving roller 87 and the pinch roller 88, and that the frictional force between the driving roller 87 and the pinch roller 88 and the frictional force between the pinch roller 88 and the recording paper are sufficiently large. In the embodiment, the moments M1 to M5 satisfy the following relational expressions.

That is, when the recording paper is not conveyed by the drive roller 87 and the pinch roller 88, the following equation (2) is established. At this time, the moment M2 works around the point A in the clockwise direction, and the moment M3 works around the point A in the counterclockwise direction.
M1 (θ) + M3> M2 (2)
Accordingly, in this case, the pinch roller holder 96 rolls upstream in the conveyance direction of the recording paper and moves backward. And the attitude | position is hold | maintained in the position (retreat position) of (theta) = theta2.

When the recording paper reaches the nipping portion of the driving roller 87 and the pinch roller 88 and the leading end of the recording paper is nipped by rotating the driving roller 87, the relationship of the following expression (3) is established. At this time, the moment M3 works around the point A counterclockwise, and the moment M5 works around the point A clockwise.
M1 (θ) + M3 <M4 (θ) + M5 (3)
At this time, the pinch roller holder 96 rolls to the downstream side in the transport direction, and the posture is held at the position θ = θ1 (transport position).

During the conveyance of the recording paper, the relationship of the following formula (4) is established. At this time, the moment M2 works clockwise around the point A, and the moment M3 works around the center A in the clockwise direction.
M1 (θ) <M2 + M3 + M4 (θ) (4)
Therefore, the pinch roller holder 96 is continuously held at the transport position D where θ = θ1.

When the trailing edge of the recording paper comes out of the nipping portion of the driving roller 87 and the pinch roller 88, the relationship of the following formula (5) is established. At this time, the moment M3 works clockwise around the point A, and the moment M5 works counterclockwise around the point A like the moment M1.
M1 (θ) + M5> M3 (5)
As can be understood from the above equation (5), only the moment M3 works as a frictional force with respect to the moment M1 (θ) + M5 generated when the trailing edge of the recording paper comes out of the holding portion of the driving roller 87 and the pinch roller 88. The moment M3 is a slight frictional force caused by the rolling bearing 125, and therefore does not act as a force for pushing the recording paper in the transport direction. Accordingly, in this case, almost all of the moment M1 (θ) + M5 acts to roll the pinch roller holder 96 upstream in the recording paper conveyance direction. Note that once the pinch roller holder 96 is retracted, the posture is maintained at the retracted position E of θ = θ2.

Even when the rear end of the recording paper comes out of the holding portion of the drive roller 87 and the pinch roller 88, even when the pinch roller holder 96 does not return to the position of θ = θ2 (retracted position E), By rotating the drive roller 87 in the reverse direction, the following formula (6) is established, and the pinch roller holder 96 can be rolled to the position of θ = θ2 (retreat position E).
M1 (θ) + M2> M3 (6)
In this case, the moment M2 works around the center A in the counterclockwise direction, and the moment M3 works around the center O in the clockwise direction.

  As described above, in the multi-function machine 1 that supports the pinch roller holder 96 via the rolling bearing 125 so as to be able to roll, the pinch roller 88 and the formula (2) to (6) By disposing the pinch roller holder 96, the holder support member 97, the coil spring 131, and the like, it is possible to reduce the amount of extrusion in the recording paper conveyance direction. In FIG. 12, since the pinch roller 88 is positioned so that the angle α is larger than the angle β, the rotational force F3 (FIG. 12) that is instantaneously generated when the leading edge of the recording paper S is pinched at the retracted position E. 13), the pinch roller 88 is rotated counterclockwise. As a result, the recording sheet S is securely held by the conveying roller pair 89. As a result, the conveyance deviation and the skew of the recording paper S do not occur, and a uniform cueing amount can be ensured.

  In addition, embodiment mentioned above is only an example of this invention, and can change suitably embodiment in the range which does not change the summary of this invention. Therefore, the support structure is not limited to the above-described support structure in which the pinch roller holder 96 is supported by the holder support member 97 and the pinch roller 88 rolls. For example, a slide moving mechanism disclosed in Japanese Patent Application Laid-Open No. 2004-168451 is applied. Is also possible. In this publication, when the trailing edge of the recording paper comes out from the clamping portion between the driving roller and the driven roller, the paper can slide and move in the conveyance direction of the recording paper and supports the driven roller. A moving mechanism is disclosed that is configured such that the driven roller is retracted to the upstream side in the transport direction in response to the reaction force from. Refer to this publication for details of this moving mechanism. Furthermore, the present invention can also be applied to the conveyance roller pair 89 in which the pinch roller 88 does not roll or slide and is always fixed at a predetermined position before and after conveyance of the recording paper.

FIG. 1 is a perspective view showing an external configuration of a multifunction machine 1 according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the internal configuration of the multifunction machine 1. FIG. 3 is an enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 4 is a plan view showing the main configuration of the printer unit 2. FIG. 5 is a perspective view showing a mechanism in the vicinity of the image recording unit 24. FIG. 6 is a block diagram illustrating a configuration of the control unit 64 of the multifunction machine 1. FIG. 7 is a perspective view showing a state in which the pinch roller holder 96 is supported by the holder support member 97. FIG. 8 is an exploded view of the holder support member 97 and the pinch roller holder 96. FIG. 9 is a perspective view showing the configuration of the rolling bearing 125. FIG. 10 is a partially enlarged view for explaining the movement range of the pinch roller holder 96. FIG. 11 is a schematic cross-sectional view showing the positional relationship between the drive roller 87 and the pinch roller 88 in the cross-sectional view of the conveying roller pair 89. FIG. 12 is a schematic cross-sectional view showing the positional relationship between the drive roller 87 and the pinch roller 88 in the cross-sectional view of the conveying roller pair 89. FIG. 13 is a schematic cross-sectional view showing the positional relationship between the drive roller 87 and the pinch roller 88 in the cross-sectional view of the conveying roller pair 89. FIG. 14 is a schematic diagram showing the positional relationship between the driving roller 87 and the pinch roller 88 by XY coordinates with the revolution center point O as the origin in a cross-sectional view of the conveying roller pair 89. FIG. 15 is a diagram illustrating a state in which the recording paper S is sandwiched by the conveyance roller pair 89 in FIG. FIG. 16 is a partial cross-sectional view showing a state in which the pinch roller holder 96 is located at the retracted position. FIG. 17 is a partial cross-sectional view showing a state in which the pinch roller holder 96 is located at the transport position. FIG. 18 is a schematic diagram for explaining a conventional recording paper transport mechanism. FIG. 19 is an enlarged view showing details of a conventional recording paper transport mechanism.

Explanation of symbols

1 ... Multifunction machine (image recording device)
DESCRIPTION OF SYMBOLS 2 ... Printer part 3 ... Scanner part 87 ... Drive roller 88 ... Pinch roller 89 ... Conveyance roller pair 96 ... Pinch roller holder 97 ... Holder support member

Claims (6)

A pair of conveying rollers having a driving roller that is rotationally driven and a driven roller that is pressed against and driven by the driving roller;
The driven roller, movably supported along a direction forming an angle of inclination α with respect to the first plane including the rotation axis of the rotating shaft and the driven roller of the drive rollers of the pressure contact state, and the conveying A support means for supporting the roller pair so as to be retractable from the drive roller to the downstream side in the conveying direction;
Provided on the downstream side of the plane perpendicular to the support direction of the support means and including the rotation axis of the driven roller, and applies a biasing force to the driven roller to press the driven roller against the driving roller. Power means,
The inclination angle α is such that the corner in the thickness direction at the tip of the medium to be transported entering the pressure contact portion of the transport roller pair in the pressure contact state is in contact with the roller surfaces of both the driving roller and the driven roller. sheet conveying those above a second plane including the rotation axis of the contact point and the driven roller between the corner portion and the roller surface of the driven roller of the conveying medium, greater than the angle β formed between the first plane apparatus. The angle β is the minimum positive solution of the following equation, where h is the thickness of the transported medium, R is the radius of the driving roller, and r is the radius of the driven roller. Sheet conveying device.

  The sheet conveying apparatus according to claim 1, wherein the biasing unit applies a biasing force in a direction opposite to a retracting direction of the driven roller.   4. The drive roller is stopped or reversely rotated for a predetermined time when the leading end of the transported medium reaches the pressure contact portion of the transport roller pair, and then driven again or forwardly. The sheet conveying apparatus according to any one of the above.   An image recording apparatus comprising: the sheet conveying apparatus according to claim 1; and an image recording unit configured to record an image on a sheet-like conveyed medium conveyed by the sheet conveying apparatus.   The image recording apparatus according to claim 5, wherein the image recording unit records an image by ejecting fine ink droplets onto a transported medium.

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