JP2013040667A - Tension adjusting mechanism, driving device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tension adjusting mechanism that can suppress the movement of a stretching roller supporting member in a tension adjusting direction when the stretching roller supporting member is screwed to a device, and to provide a driving device and an image forming apparatus.SOLUTION: A screw inserting hole 111a is provided at a first fixed portion 107b of a bracket 107 to which a secondary sweeping motor 109 is screwed and which supports rotatably a driving pulley 101. The screw inserting hole has a substantially cross shape having a portion extending in parallel with a line segment AB connecting a rotational center of a driven pulley 103 and that of the driving pulley 101 which segment is a tension adjusting direction, and a portion extending in a direction orthogonal with respect to the line segment AB.

Description

  The present invention relates to a tension adjusting mechanism, a driving device, and an image forming apparatus.

  2. Related Art There is known an ink jet type image forming apparatus that records an image by ejecting ink droplets toward a recording sheet by an ink jet head that is an ink ejecting means mounted on a carriage that moves in the main scanning direction. Inkjet image forming apparatuses form an image by the ink droplets ejected from the inkjet head directly landing on the recording paper. In order to achieve high image quality, the ink droplet landing position on the recording paper Need to increase accuracy.

  In order to increase the landing position accuracy, it is necessary to convey the recording paper with high accuracy. In an inkjet image forming apparatus, an image is formed on a recording sheet while repeatedly conveying and stopping the recording sheet. Therefore, the drive transmission delay during the intermittent driving operation of the conveying belt that conveys the recording sheet is stopped. This greatly affects the position accuracy and leads to a decrease in landing position accuracy. Therefore, in the inkjet image forming apparatus, the transmission mechanism that transmits the driving force to the conveyance belt that conveys the recording paper is not a gear drive transmission mechanism that generates backlash as one of the causes of the drive transmission delay, A timing belt drive transmission mechanism suitable for precision drive is adopted.

  In the timing belt drive transmission mechanism, if the tension of the timing belt is less than the target tension, tooth skipping or timing belt vibration occurs, and the recording paper stop position accuracy deteriorates. If the timing belt is stronger than the target tension, the driving torque increases, power consumption increases, and an excessive load is applied to the bearing portion for bearing the tension roller, resulting in an early life of the apparatus. Japanese Patent Application Laid-Open No. 2004-228561 describes a drive device including a tension adjustment mechanism that adjusts the tension of a timing belt as a belt member.

FIG. 10 is a schematic configuration diagram of a tension adjusting mechanism described in Patent Document 1.
As shown in FIG. 10, the tension adjustment mechanism 500 described in Patent Document 1 includes a bracket 510 as a stretching roller holding member that rotatably supports a shaft 506 of a stretching roller 505 that stretches a timing belt 502, and And a spring 516 as an urging unit for pressing the tension roller 505 against the timing belt 502. One end of the spring 516 is fixed to the spring receiver 515 of the apparatus main body side plate, and the other end is fixed to the shaft 506 of the stretching roller to pull the stretching roller 505. The bracket 510 is formed with a long hole-like screw insertion hole 511 extending in the tension adjustment direction (left and right direction in the figure) in which two screws 512 are inserted at a predetermined interval. Two screws 512 are inserted into the bracket 510, and the bracket 510 is fixed to the apparatus main body by these two screws 512.

  To adjust the tension of the timing belt 502, first, the two screws 512 are loosened. Then, the tension roller 506 is moved to the right side in the drawing together with the bracket 510 by the tension force of the spring 516, and the movement of the tension roller 505 is stopped at a position where the tension of the timing belt 502 and the tension force of the spring 516 are balanced. As a result, the timing belt 502 is stretched with a target tension. Next, the bracket 510 is fastened to the apparatus main body with two screws 512.

  However, in the configuration described in Patent Document 1, when the bracket 510 is fixed to the apparatus main body with the screw 512 after tension adjustment, the fastening torque of the screw 512 in the tension adjustment direction is applied to the bracket 510 as shown in FIG. T1 and T2 work. Specifically, the fastening torque T1 is applied in the direction of loosening the tension in the direction above the screw insertion hole 511 of the bracket 510, and the tension is increased below the screw insertion hole 511 of the bracket 510 in the figure. A fastening torque T2 is applied in the direction. When screwed perpendicularly to the surface of the bracket 510, the fastening torque T1 applied to the upper side in the figure relative to the screw insertion hole 511 of the bracket 510 and the fastening torque T2 applied to the lower side in the figure relative to the screw insertion hole 511 are Since they are the same, they cancel each other and the bracket 510 is fixed without moving. However, when the screw is obliquely attached to the surface of the bracket 510, the contact pressure applied on the upper side of the screw insertion bracket 511 of the screw head bracket 510 and the screw insertion hole 511 in the drawing. The contact pressure applied to the lower side is different. Therefore, there can be a difference between the fastening torque T1 applied to the upper side in the drawing with respect to the screw insertion hole 511 of the bracket 510 and the fastening torque T2 applied to the lower side in the drawing with respect to the screw insertion hole 511. As a result, there is a problem that the bracket 510 moves in the tension adjustment direction due to the fastening torque of the screw 512 and is out of the target tension.

  The above problem is not limited to the tension adjusting mechanism of the timing belt, and a similar problem occurs in the tension adjusting mechanism that adjusts the tension of the belt member.

  The present invention has been made in view of the above problems, and its purpose is to suppress the tension roller holding member from moving in the tension adjustment direction when the tension roller holding member is screwed to the apparatus. It is an object of the present invention to provide a tension adjusting mechanism, a driving device, and an image forming apparatus that can do the same.

  In order to achieve the above object, the invention of claim 1 is characterized in that one of a plurality of stretching rollers for stretching a belt member is rotatably supported, and a screw is inserted into a screw insertion hole into which a screw is inserted. A tension roller holding member fixed to the apparatus main body by the screw, and a biasing means for biasing the tension roller holding member in a direction of applying a tension of the belt member, and inserting the tension roller holding member The hole extends in the tension adjusting direction of the belt member, and the tension roller holding member is fixed to the apparatus main body by the screw at a place where the tension of the belt member and the biasing force of the biasing means are balanced. In the tension adjusting mechanism, the tension of the screw head so that the portion of the screw head that is farthest from the rotation center of the screw in a direction orthogonal to the tension adjustment direction of the belt member does not contact the tension roller holding member. Rack holding It is characterized in that to constitute a timber.

  According to the present invention, the position of the head of the screw that is farthest from the rotation center of the screw in the direction orthogonal to the tension adjustment direction of the belt member does not contact the tension roller holding member. The fastening torque in the direction parallel to the tension adjustment direction applied to the holding member from the head of the screw is the tension head in the direction farthest from the rotation center of the screw in the direction perpendicular to the tension adjustment direction of the belt member. It can be made smaller than that in contact with the roller holding member. Therefore, the screw is inserted into the screw insertion hole obliquely with respect to the tension roller holding member, and the tension roller holding of the screw head is held on one side and the other side in the direction perpendicular to the tension adjustment direction across the screw insertion hole. Even if the contact pressure with respect to the member is different, the fastening torque difference in the direction parallel to the tension adjustment direction between the one side and the other side in the direction orthogonal to the tension adjustment direction across the screw insertion hole can be reduced. Therefore, it is possible to suppress the stretching roller holding member from moving in the tension adjustment direction. Thereby, the shift | offset | difference with respect to the target tension | tensile_strength of the belt member after screwing a tension roller holding member to an apparatus can be made small compared with the tension adjustment mechanism of patent document 1. FIG.

1 is a perspective view of an ink jet recording apparatus as an image forming apparatus according to an embodiment as viewed from the front. FIG. 3 is a side view showing an outline of the mechanism of the inkjet recording apparatus. FIG. 2 is a plan view showing an outline of a main part of the ink jet recording apparatus. The perspective view of a drive device. The front view of a drive device. The front view of the drive device before tension spring attachment. The front view of the drive device before bracket fixation. The figure explaining a mode that the screw was inserted in the screw insertion hole of the 1st fixing | fixed part, and the 1st fixing | fixed part was fixed to the motor attachment board. The schematic block diagram of the tension adjustment mechanism of a conveyance belt. The schematic block diagram of the conventional tension | tensile_strength adjustment mechanism.

Hereinafter, embodiments of an image forming apparatus to which the present invention is applied will be described.
FIG. 1 is an explanatory perspective view of an ink jet recording apparatus 100 as an image forming apparatus according to an embodiment as viewed from the front side. The ink jet recording apparatus 100 includes an apparatus main body 1, a paper feed tray 2 for loading paper mounted on the apparatus main body 1, and paper on which an image is recorded (formed) by being detachably mounted on the apparatus main body 1. And a paper discharge tray 3 for stocking. Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons, a display, and the like.

  The cartridge loading unit 4 includes a plurality of recording liquids (inks) that are different color materials, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. Ink cartridges 10k, 10c, 10m, and 10y, which are recording liquid cartridges as recording liquid storage means, are inserted from the front side of the apparatus main body 1 toward the rear side. Can be loaded. A front cover (cartridge cover) 6 that is opened when the ink cartridge 10 is attached or detached is provided on the front side of the cartridge loading unit 4 so as to be openable and closable. Further, the ink cartridges 10k, 10c, 10m, and 10y are configured to be loaded side by side in a vertical state.

  In the operation / display unit 5, the remaining amounts of the ink cartridges 10k, 10c, 10m, and 10y for each color are near-end at an arrangement position corresponding to the mounting position (arrangement position) of the ink cartridges 10k, 10c, 10m, and 10y for each color. The remaining amount display portions 11k, 11c, 11m, and 11y for each color for displaying the end are arranged. Further, the operation / display unit 5 is also provided with a power button 12, a paper feed / print resume button 13, and a cancel button 14.

  Next, the mechanism part of the ink jet recording apparatus 100 will be described with reference to FIGS. 2 is a side view showing the outline of the mechanism, and FIG. 3 is a plan view of the main part.

  In the mechanism part of the ink jet recording apparatus 100, the carriage 33 is mainly composed of a guide rod 31 and a stay 32 (see FIG. 2), which are guide members horizontally mounted on the left and right side plates 21A and 21B (see FIG. 3) constituting the frame 21. It is slidably held in the scanning direction, and is moved and scanned in the direction indicated by the arrow (carriage main scanning direction) in FIG. 3 via a timing belt by a main scanning motor (not shown).

  As described above, the carriage 33 includes a first recording head 34 a having a nozzle row for ejecting black (K) ink droplets and a nozzle row for ejecting cyan (C) ink droplets, and magenta (M). A second recording head 34b having a nozzle row for ejecting ink droplets and a nozzle row for ejecting yellow (Y) ink droplets is arranged in a direction crossing a plurality of ink ejection ports with the main scanning direction. It is mounted with the droplet discharge direction facing downward.

  As the ink jet head constituting the recording heads 34a and 34b, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, a metal phase caused by a temperature change A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet can be used.

  A driver IC is mounted on the recording heads 34a and 34b, and is connected to a control unit (not shown) via a harness (flexible print cable) 22. The carriage 33 is equipped with a head tank 35 for each color for supplying each color ink to each recording head 34. As described above, each color head tank 35 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 via the ink supply tube 36 of each color. The cartridge loading section 4 is provided with a supply pump unit 24 for feeding the ink in the ink cartridge 10, and the ink supply tube 36 is attached to the rear plate 21 </ b> C constituting the frame 21 in the middle of turning. It is held by the locking member 25.

  As shown in FIG. 2, one sheet 42 is fed from the sheet stacking unit 41 as a sheet feeding unit for feeding a sheet 42 as a recording sheet stacked on a sheet stacking unit (pressure plate) 41 of the sheet feeding tray 2. Opposite to the half-moon roller (sheet feeding roller) 43 and the sheet feeding roller 43 that are separated and fed one by one, a separation pad 44 made of a material having a large friction coefficient is provided, and this separation pad 44 is urged toward the sheet feeding roller 43 side. Yes. In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a pressing member 48 having 49. Further, a transport belt unit that is a transport unit for electrostatically attracting the fed paper 42 and transporting the paper 42 at a position facing the recording head 34 is provided. The conveyor belt unit includes an endless conveyor belt 51. The conveyor belt 51 is stretched between a conveyor roller 52 and a tension roller 53, and circulates in the belt conveyance direction (sub-scanning direction). ing. Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. Further, a guide member 57 is disposed on the back side of the conveyor belt 51 in correspondence with a printing area by the recording head 34.

  The conveyance belt 51 rotates in the belt conveyance direction (sub-scanning direction) in FIG. 3 when the conveyance roller 52 is rotationally driven with timing by the sub-scanning motor 109 (see FIG. 4). Further, as shown in FIG. 2, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and A paper discharge roller 63 is provided, and a paper discharge tray 3 is provided below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 3, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. Yes. The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a and 82b (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper blade 83 that is a blade member for wiping, an empty discharge receiver 84 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and the like are provided. . Here, the cap 82a is a suction and moisture retention cap, and the cap 82b is a moisture retention cap.

  The waste liquid of the recording liquid generated by the maintenance and recovery operation by the maintenance and recovery mechanism 81, the ink discharged to the cap 82, the ink attached to the wiper blade 83 and removed by the wiper cleaner 85, and the idle discharge receiver 94 was idled. The ink is discharged and stored in a waste liquid tank (not shown). Further, as shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 33, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An empty discharge receiver 88 for receiving the droplets at the time is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the recording head 34.

  In the ink jet recording apparatus 100 configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheets 42 fed substantially vertically upward are guided by the guide member 45, It is sandwiched between the counter roller 46 and conveyed, and further, the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °. At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control unit (not shown) to the charging roller 56 alternately, that is, an alternating voltage is applied and the conveying belt 51 alternates. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction, which is the circumferential direction. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  When the sheet 42 conveyed by the conveyance belt 51 reaches a position facing the recording head 34, the conveyance belt 51 is stopped and the movement of the sheet 42 is stopped. Then, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, during printing (recording) standby, the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the recording head 34 is capped by the cap 82 to keep the nozzles in a wet state, thereby preventing ejection failure due to ink drying. . Further, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the recording head 34 capped by the cap 82 (referred to as “nozzle suction” or “head suction”), and the thickened recording liquid and bubbles are discharged. Perform recovery action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

Next, a driving device for rotationally driving the conveyance belt 51, which is a characteristic point of the present embodiment, will be described.
FIG. 4 is a perspective view of the driving device 150, and FIG. 5 is a front view of the driving device 150. In FIG. 5, the display of the rotary encoder 102 is omitted.
The driving device 150 includes a sub-scanning motor 109 as a driving source, a transmission mechanism 130 that transmits the driving force of the sub-scanning motor using the timing belt 105, and tension adjustment as tension adjusting means that adjusts the tension of the timing belt 105. Mechanism 120.

  The transmission mechanism 130 includes a driving pulley 101 as a stretching roller fixed to the tip of the motor shaft of the sub-scanning motor 109, a driven pulley 103 as a stretching roller fixed to the shaft 104 of the conveying roller 52, and a driving pulley. 101 and a timing belt 105 stretched around a driven pulley 103. In addition, a rotary encoder 102 is provided on the shaft 104 of the transport roller 52, and based on a pulse signal from the rotary encoder 102, control is performed to transport the paper 42 by a predetermined amount and stop.

  As shown in FIG. 5, the tension adjusting mechanism 120 includes a bracket 107 as a tension roller holding member that rotatably supports a driving pulley 101 as a tension roller, and a bracket 107, with a sub-scanning motor 109 screwed thereto. The timing belt 105 includes a tension spring 106 as an urging means for urging in the tension applying direction. One end of the tension spring 106 is attached to a spring receiver 108 a of a motor attachment plate 108 provided on the side plate 21 </ b> A, and the other end is attached in an extended state to a spring receiver 114 provided on the bracket 107. The spring receiver 114 and the spring receiver 108a are provided on an extension line of the line segment AB connecting the rotation center of the driven pulley 103 and the rotation center of the drive pulley, and are tension springs attached to the spring receivers 114 and 108a. 106 urges the bracket 107 in a direction away from the driven pulley 103 in parallel with the line segment AB.

  The bracket 107 has a motor fixing portion 107a to which the sub-scanning motor 109 is fixed, and a first fixing portion 107b and a second fixing portion 107c for fixing to the motor mounting plate 108. The first and second fixing portions 107b and 107c protrude from the motor mounting plate 108 to the side opposite to the sub-scanning motor 109 side, and screw insertion holes 111a and 111b (see FIG. 6) into which screws 112 are inserted, respectively. I have. As shown in FIG. 6, the screw insertion hole 111 a provided in the first fixing portion 107 b is parallel to a line segment AB connecting the rotation center of the driven pulley 103 and the rotation center of the drive pulley 101, which is the tension adjustment direction. It has a substantially cross shape having an extending portion and a portion extending in a direction orthogonal to the line segment AB. On the other hand, the screw insertion hole 111b of the second fixing portion 107c has a long hole shape extending in parallel with a line segment AB connecting the rotation center of the driven pulley 103 and the rotation center of the drive pulley, which are tension adjustment directions.

  Further, the first fixing portion 107b and the second fixing portion 107c are each provided with a notch 113a extending in parallel with a line segment AB connecting the rotation center of the driven pulley 103 and the rotation center of the drive pulley, which are tension adjustment directions. 113b are provided. The notch 113a of the first fixed part 107b is provided on the side opposite to the driven pulley side of the first fixed part 107b, and the notch 113b of the second fixed part 107c is provided on the driven pulley side of the second fixed part 107c. Is provided. These cutouts 113a and 113b abut against a rotation restricting convex portion 110 that is a rotation restricting means protruding from the motor mounting plate 108, restricts the rotation of the bracket 107, and supports the bracket 107 before screwing.

  The bracket 107 is inserted into the apparatus main body from the conveying belt 51 side after the sub-scanning motor 109 is screwed to the motor fixing portion 107a. Then, the first and second fixing portions 107a and 107b are caused to pass through the opening 141 of the motor mounting plate 108 and face the surface of the motor mounting plate 108 opposite to the conveyance belt 51. Specifically, a notch 141a is provided in the upper portion of the opening 141 in the figure, and first, the first fixing portion 107b is passed through the opening 141 and the motor mounting plate 108 is opposite to the conveyance belt 51. Opposite the surface. Next, when the connecting portion of the first fixing portion 107b to the motor fixing portion 107a is abutted against the upper end of the notch portion 141a of the opening portion 141, the second fixing portion 107c can be passed through the opening portion 141. Next, when the second fixing portion 107c is passed through the opening 141, the bracket 107 is rotated clockwise in the figure, and the rotation restricting convex portion 110 is inserted into the notches 113a and 113b provided in the fixing portions 107b and 107c. (See FIG. 6). Thereby, the rotation restricting convex portion 110 abuts on the notches 113a and 113b, and the bracket 107 is supported on the apparatus main body (the motor mounting plate 108) by the rotation restricting convex portion 110. When the timing belt 105 is laid over the driven pulley 103 and the driving pulley 101, the tension spring 106 is attached to the spring receiving portion 114 of the bracket 107 and the spring receiving portion 108a provided on the motor mounting plate 108. Then, the bracket 107 is biased in a direction away from the driven pulley 103 by the tension spring 106. As a result, the drive pulley 101 that is rotatably supported by the bracket 107 moves together with the bracket 107 in a direction away from the driven pulley 103 and contacts the timing belt 105. The bracket 107 (drive pulley 101) stops moving at a place where the biasing force of the tension spring 106 and the restoring force of the timing belt 105 are balanced (see FIG. 7). Thereby, a target tension is applied to the timing belt 105. When a target tension is applied to the timing belt 105, first, the screw 112 is inserted into the screw insertion hole 111a of the first fixing portion 107b, and screwed into the screw hole 108b (see FIG. 7) provided in the motor mounting plate 108. Then, the first fixing portion 107b is fixed to the motor mounting plate 108.

FIG. 8 is a diagram illustrating a state in which the screw 112 is inserted into the screw insertion hole 111a of the first fixing portion 107b and the first fixing portion 107b is fixed to the motor mounting plate 108. In the figure, 112 a indicates the head of the screw 112, and 112 b in the figure is the screw portion of the screw 112.
FIG. 8A shows a state of fixing when the bracket 107 is at the reference mounting position, and FIG. 8B shows a state when the bracket 107 is closer to the driven pulley 103 than the reference mounting position. FIG. 8C is a diagram showing a state of fixation when the bracket 107 is on the side farther from the driven pulley 103 than the reference attachment position.

  As shown in FIG. 8A, when the urging force of the tension spring 106 and the tension of the timing belt 105 are balanced when the bracket 107 is at the reference position, the tension is orthogonal to the tension adjustment direction of the head 112a of the screw 112. The end in the direction (black circle in the figure) does not abut against the bracket 107 (first fixing part 107b), and the left and right parts of the screw head 112a in the figure are bracket 107 (first fixing). Part 107b). As a result, the fastening torque applied to the bracket 107 (first fixing portion 107b) at the time of screw fastening is a direction orthogonal to the tension adjustment direction as shown in the figure. As a result, when the first fixing portion 107 b is fixed to the motor mounting plate 108 with the screw 112, it is possible to suppress the bracket 107 from moving in the tension adjustment direction due to the fastening force of the screw 112.

  As shown in FIG. 8B, when the bracket 107 is closer to the driven pulley 103 than the reference mounting position, the end of the screw 112 in the direction orthogonal to the tension adjustment direction of the head 112a (in the drawing) The black circle) does not contact the bracket 107 (first fixing portion 107b), and the left portion of the screw head 112a in the drawing contacts the bracket 107 (first fixing portion 107b). Also in this case, the fastening torque applied to the bracket 107 at the time of screw fastening becomes a direction orthogonal to the tension adjustment direction as shown in the figure, and when the first fixing portion 107b is fixed to the motor mounting plate 108 with the screw 112, the screw 112 It is possible to suppress the bracket 107 from moving in the tension adjustment direction by the fastening force.

  Further, as shown in FIG. 8C, when the bracket 107 is on the side farther from the driven pulley 103 than the reference mounting position, the end portion of the screw 112 in the direction orthogonal to the tension adjustment direction of the head portion 112a. (Black circle in the figure) does not contact the bracket 107 (first fixing portion 107b), and the right portion of the screw head 112a in the drawing contacts the bracket 107 (first fixing portion 107b). Also in this case, the fastening torque applied to the bracket 107 at the time of screw fastening becomes a direction orthogonal to the tension adjustment direction as shown in the figure, and when the first fixing portion 107b is fixed to the motor mounting plate 108 with the screw 112, the screw 112 It is possible to suppress the bracket 107 from moving in the tension adjustment direction by the fastening force.

  Further, as shown in FIGS. 8A to 8C, when the first fixing portion 107 is fastened with the screw 112, the fastening torque acts in a direction orthogonal to the tension adjustment direction. There is a concern that the fastening torque of 112 may move or rotate in a direction orthogonal to the tension adjustment direction. However, in this embodiment, when the first fixing portion 107 is attached to the motor mounting plate 108 with the screw 112, the rotation restricting convex portion 110 abuts against the notches 113a and 113b of the bracket 107 as shown in FIG. ing. Therefore, when the first fixing portion 107 is fastened with the screw 112, even if the bracket 107 tries to move or rotate in the direction orthogonal to the tension adjustment direction by the fastening torque of the screw 112, the rotation restricting convex portion 110 is Regulate such movement. Therefore, when the first fixing portion 107 b is fastened with the screw 112, the bracket 107 does not move or rotate in a direction orthogonal to the tension adjustment direction due to the fastening torque of the screw 112.

  As described above, when the first fixing portion 107b of the bracket 107 is fixed to the motor mounting plate 108 with the screw 112, the screw is inserted into the screw insertion hole 111b of the second fixing portion 107c, and the second fixing portion 107c is fixed to the motor mounting plate. It is fixed to 108 with a screw 112. Since the screw insertion hole 111b of the second fixing portion 107c has a long hole shape extending in the tension adjustment direction, when the second fixing portion 107c is fixed to the motor mounting plate 108 with the screw 112, the tension of the head portion 112a of the screw 112 is increased. An end portion in a direction orthogonal to the adjustment direction comes into contact with the bracket 107 (second fixing portion 107c). As a result, when the second fixing portion 107c is fixed to the motor mounting plate 108, a fastening torque is applied to the second fixing portion 107c in the tension adjustment direction. However, at this time, since the first fixing portion 107b is fixed to the motor mounting plate 108, the second fixing portion 107c is moved in the tension adjustment direction by the fastening torque when the second fixing portion 107b is fixed with the screw 112. When such a force is generated, the bracket itself tries to rotate around the screw 112 fixing the first fixing portion 107b, and the bracket 107 itself does not translate in the tension adjustment direction. Even if the bracket 107 is about to rotate, the rotation of the bracket 107 is restricted by the rotation restricting convex portion 110 that abuts the notches 113a and 113b of the fixing portions 107b and 107c, so the second fixing portion 107b is attached to the motor. When fixed to the plate 108, the posture and position of the bracket 107 do not change.

  Thereby, even if the bracket 107 is fixed to the apparatus main body (motor mounting plate), the tension of the timing belt 105 does not fluctuate and a predetermined tension can be maintained. Thereby, tooth skipping and vibration of the timing belt 105 are suppressed, and the paper 42 can be stopped at a predetermined position with high accuracy. In addition, an unnecessary load is not applied to the transport roller 52 and the like, and it is possible to suppress an increase in power consumption due to an early life or an increase in torque of the sub-scanning motor 109.

  Further, it is necessary to screw the motor mounting plate 108 from the first fixing portion 107b of the bracket 107. Therefore, by stating that it is screwed from the first fixing portion 107b in the work specification, or by marking the fixing order on the first fixing portion 107b and the second fixing portion 107c of the bracket 107, The first fixing portion 107b can be screwed. Also, by making the screw insertion hole 111b of the second fixing portion 107c substantially cross-shaped like the screw insertion hole 111a of the first fixing portion 107b, which of the first fixing portion 107b and the second fixing portion 107c is made. Even if it is fixed to the motor mounting plate 108 first, it is possible to suppress the bracket 107 from moving in the tension adjustment direction.

  Further, when the tension of the timing belt 105 is readjusted during maintenance or the like, the screw 112 of the first fixing portion 107b and the screw 112 of the second fixing portion 107c are loosened. Then, the bracket 107 moves in the tension adjustment direction and stops at a position where the biasing force of the tension spring 106 and the tension of the timing belt 105 are balanced. When the operation is stopped, the first fixing portion 107b is fixed to the motor mounting plate 108 and the second fixing portion 107c is fixed to the motor mounting plate 108 as described above. Thus, in the present embodiment, the timing belt 105 can be stretched with a predetermined tension without moving the bracket 107 while measuring with a measuring instrument so that the timing belt 105 has a predetermined tension. And tension adjustment work can be easily performed.

  In the present embodiment, the conveyor belt unit and the timing belt 105 can be easily replaced. More specifically, when replacing the conveyor belt unit or the timing belt 105, the screw 112 of the first fixing portion 107b and the screw 112 of the second fixing portion 107c are loosened, the tension spring 106 is removed, and the timing is changed. The belt 105 is loosened. Thereby, the timing belt 105 can be easily removed and a new timing belt 105 can be easily attached. Further, since the tension of the timing belt 105 is released, the conveyor belt unit can be easily detached from the apparatus main body, and a new conveyor belt unit can be attached to the apparatus. At this time, the bracket 107 is supported by the rotation restricting convex portion 110. Even if the screw 112 of the first fixing portion 107b and the screw 112 of the second fixing portion 107c are loosened and the tension spring 106 is removed, It does not move or rotate vertically. Therefore, the tension spring 106 can be attached to the spring receiving portion 114 of the bracket 107 without performing any special positioning operation on the bracket 107 after replacing the conveyor belt unit or the timing belt. Therefore, it is possible to expect the effect of reducing the replacement work time of the transport belt unit and the timing belt 105.

  In the present embodiment, the screw insertion hole 111a of the first fixing portion 107b is formed in a substantially cross shape, and the end of the direction perpendicular to the tension adjustment direction of the screw head 112a is not brought into contact with the first fixing portion 107b when the screw is tightened. However, it is sufficient that the end portion in the direction orthogonal to the tension adjustment direction of the screw head 112a does not come into contact with the first fixing portion 107b when the screw is fastened. For example, the screw insertion hole 111a of the first fixing portion 107b has a long hole shape extending in the tension adjustment direction, and the periphery of the screw insertion hole 111a in the direction orthogonal to the tension adjustment direction is formed in a concave shape so You may make it the direction edge part orthogonal to the tension adjustment direction of the part 112a not contact | abut to the 1st fixing | fixed part 107b.

  In the present embodiment, the tension spring 106 is used as the urging means. However, for example, an elastic body such as rubber may be used.

  In this embodiment, the example in which the present invention is applied to the tension adjusting mechanism of the timing belt 105 has been described. However, the present invention can also be applied to, for example, a tension adjusting mechanism that adjusts the tension of the transport belt 51. . In this case, as shown in FIG. 9, the tension roller 53 is rotatably supported by the bracket 107. In the bracket 107, a long screw-shaped screw insertion hole 111 into which the two screws 112 are inserted is inserted, and the screw insertion hole 111 is screwed up and down (in a direction perpendicular to the tension adjustment direction) in the figure. A long hole-like retraction hole 122 extending in parallel with the insertion hole 111 is provided. The bracket 107 is supported by a plurality of roller members 123 so as to be slidable in the tension adjustment direction.

  The tension adjusting mechanism shown in FIG. 9 fixes the bracket 107 with the two screws 112 when the tension roller 53 stops at a place where the tension of the tension spring 106 and the tension of the conveying belt 51 is balanced. At this time, both ends of each screw 112 in the direction orthogonal to the tension adjustment direction of the head face the retraction hole 122, and when the bracket 107 is fixed to the apparatus main body with the two screws 112, Both ends in the direction orthogonal to the tension adjustment direction of the head do not contact the bracket 107. As a result, a fastening torque as shown in the drawing acts on the bracket 107, and a fastening torque parallel to the tension adjustment direction does not work. In addition, when the brackets 107 are fixed with the screws 112, a fastening torque as shown in the drawing works and a force that rotates the bracket 107 is generated, but the bracket 107 is supported by a plurality of roller members 123. There is no such thing as rotating. That is, in the configuration shown in FIG. 9, these roller members 123 function as rotation restricting means for restricting the rotation of the bracket 107. Therefore, even in this tension adjusting mechanism, the tension of the conveyor belt 51 does not change after the bracket is fastened, and a predetermined tension can be maintained. As a result, it is possible to prevent the conveyance belt 51 from slipping between the conveyance rollers 52 and shifting the paper conveyance stop position.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(1)
One of a plurality of stretching rollers such as a pulley for stretching a belt member such as the timing belt 105 is rotatably supported, and a screw is inserted into a screw insertion hole into which a screw is inserted, and is fixed to the apparatus main body by the screw. A tension roller holding member such as a bracket, and a biasing means such as a tension spring that biases the tension roller holding member in the direction of tension of the belt member. The insertion hole of the tension roller holding member is In the tension adjusting mechanism that extends in the tension adjusting direction of the belt member and the tension roller holding member is fixed to the apparatus main body by the screw at a place where the tension of the belt member and the biasing force of the biasing means are balanced. The portion of the screw head that is furthest away from the rotation center of the screw in the direction perpendicular to the tension adjustment direction of the belt member does not come into contact with the tension roller holding member. And configure Sulfur butterfly rack holding member. By providing such a configuration, as described above, when the tension roller holding member is screwed to the apparatus main body, the tension roller holding member is prevented from moving in the tension adjusting direction and changing the tension. can do.

(2)
In the tension adjustment mechanism according to the aspect described in (1) above, the position of the head portion of the screw that is farthest from the rotation center of the screw of the tension roller holding member in the direction orthogonal to the tension adjustment direction of the belt member; Opposing portions were formed in a hole shape or a concave shape. Thereby, it is possible to prevent the end portion of the screw head in the direction orthogonal to the tension adjusting direction of the belt member from coming into contact with the tension roller holding member.

(3)
In the tension adjusting mechanism according to the aspect described in (1) or (2) above, a rotation restricting means for restricting the rotation of the stretching roller holding member is provided. As a result, when the tension roller holding member is fastened to the apparatus main body, the tension roller holding member is not rotated, and it is possible to further suppress fluctuations in tension during screwing.

(4)
Further, in the tension adjusting mechanism according to the aspect described in (3) above, the rotation restricting means is constituted by a plurality of abutting means such as a rotation restricting convex portion that abuts against the stretching roller holding member and restricts rotation. . As a result, the tension roller holding member does not rotate, and it is possible to further suppress fluctuations in tension during screwing.

(5)
In the tension adjustment mechanism according to the aspect described in (4) above, the tension roller holding member is supported by a plurality of abutting portions so as to be movable in the tension adjustment direction of the belt member. Thereby, even if the bracket is not fixed with a screw, the bracket does not fall off from the apparatus main body. Therefore, it is possible to easily adjust the tension.

(6)
Further, in the driving device including a driving source such as a sub-scanning motor, a transmission mechanism that transmits a driving force of the driving source using a timing belt, and a tension adjusting unit that adjusts the tension of the timing belt, The tension adjusting mechanism according to any one of the above (1) to (5) was used. Thereby, the timing belt can be set to a target tension. Thereby, it becomes looser than the target tension, and the occurrence of tooth skipping and timing belt vibration can be suppressed. Also, it is too strong than the target tension, which increases drive torque, increases power consumption, and prevents the tension roller and timing belt from being loaded more than necessary, resulting in early life. Can do.

(7)
An image forming apparatus comprising: an image forming unit that forms an image on a recording sheet; a recording sheet conveying unit that conveys the recording sheet to the image forming unit; and a driving unit that drives a driven member provided in the apparatus main body. The drive device of the aspect described in (6) above was provided as drive means. Thereby, the driven member can be rotationally driven with high accuracy, and a high-quality image can be obtained.

(8)
Further, in the image forming apparatus according to the aspect described in (7), the image forming unit forms an image by ejecting ink onto the recording paper. ) Was used. Accordingly, the recording paper can be conveyed with high accuracy, and ink droplets can be landed on the recording paper with high accuracy. Thereby, a high quality image can be obtained.

100: inkjet recording apparatus 101: driving pulley 103: driven pulley 105: timing belt 106: tension spring 107: bracket 107a: motor fixing portion 107b: first fixing portion 107c: second fixing portion 108: motor mounting plate 108a: spring support Portion 108b: Screw hole 109: Sub scanning motor 110: Rotation restricting convex portions 111a, 111b: Screw insertion hole 112: Screw 112a: Screw head 114: Spring receiving portion 120: Tension adjusting mechanism 122: Retraction hole 123: Roller member 130 : Transmission mechanism 141 Opening 150: Drive device

JP-A-5-107827

Claims (8)

A tension roller holding member that rotatably supports one of a plurality of tension rollers that stretch the belt member, is inserted into a screw insertion hole into which a screw is inserted, and is fixed to the apparatus main body by the screw. When,
An urging means for urging the tension roller holding member in the tension applying direction of the belt member;
The screw insertion hole of the tension roller holding member extends in the tension adjustment direction of the belt member, and the tension roller holding member is a portion where the tension of the belt member and the biasing force of the biasing means are balanced. In the tension adjustment mechanism fixed to the apparatus main body by the screw,
The tension holding member is configured so that the position of the head of the screw that is farthest from the rotation center of the screw in a direction orthogonal to the tension adjustment direction of the belt member does not contact the tension roller holding member. Tension adjustment mechanism characterized by In the tension adjustment mechanism according to claim 1,
The portion facing the portion of the head of the screw that is farthest from the rotation center of the screw of the tension roller holding member in the direction orthogonal to the tension adjustment direction of the belt member is a hole shape or a concave shape. Features a tension adjustment mechanism. The tension adjusting mechanism according to claim 1 or 2,
A tension adjusting mechanism comprising a rotation restricting means for restricting the rotation of the tension roller holding member. In the tension adjustment mechanism of claim 3,
A tension adjusting mechanism, wherein the rotation restricting means comprises a plurality of abutting members that abut against the stretching roller holding member and restrict rotation. In the tension adjustment mechanism according to claim 4,
A tension adjusting mechanism, wherein the tension roller holding member is supported by the plurality of abutting portions so as to be movable in a tension adjusting direction of the belt member. A driving source;
A transmission mechanism that transmits the driving force of the driving source using a timing belt;
In a drive device comprising tension adjusting means for adjusting the tension of the timing belt,
6. A driving apparatus using the tension adjusting mechanism according to claim 1 as the tension adjusting means. An image forming unit that forms an image on recording paper;
Recording paper conveying means for conveying the recording paper to the image forming unit;
In an image forming apparatus provided with a driving unit that drives a driven member provided in the apparatus main body,
An image forming apparatus comprising the driving device according to claim 6 as the driving means. The image forming apparatus according to claim 7.
The image forming unit discharges ink onto the recording paper to form an image.
An image forming apparatus using the driving device according to claim 6 as a driving unit of the recording paper conveying unit.

Images