JP2019158089A - Belt device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt device capable of reducing a worker's labor when removing an endless belt 151. SOLUTION: In a belt device having a tension applying body 161 for applying tension by pressing to an endless belt 151, a holding body 158 for holding the tension applying body 151, and an urging means 162 for urging the holding body 162 in the belt pressing direction. Locking means 164 and 165 for locking the body 158 so as not to be moved by the urging force by the urging means 162 are provided. By this locking, the worker can separate the tension applying body 161 from the endless belt 151 without receiving the urging force by the urging means 162, so that the labor of the worker can be reduced. [Selection diagram] FIG. 11

Description

  The present invention relates to a belt device and an image forming apparatus including the belt device.

  2. Description of the Related Art Conventionally, a belt device having a tension applying body that applies tension to an endless belt by pressing, and an urging unit that exerts an urging force for urging the tension applying body in the belt pressing direction is known.

  For example, Patent Document 1 includes a rotational force transmission belt that is an endless belt, and a belt tensioner that includes a tension roller that is a tension applying body that applies tension to the belt and a coil spring that is a biasing unit. Yes. The tension roller of the belt tensioner is rotatably provided on one end side of a lever that can rotate around a rotation axis. The coil spring is fixed to the support so as to pull the other end of the lever. When the lever tries to rotate around the rotation axis by the pulling force of the coil spring, a tension roller provided on one end side of the lever comes into contact with the outer surface of the loop of the rotational force transmission belt and presses the rotational force transmission belt. By this pressing, tension is applied to the rotational force transmission belt.

  In this belt device, when removing the torque transmission belt from the pulley in the loop for maintenance, etc., it is necessary to expand the lever against the pulling force of the coil spring to separate the tension roller from the torque transmission belt. There is. Since the pulling force of the coil spring that applies a large tension to the rotational force transmission belt is strong, there has been a problem that a large labor is imposed on the operator in the above-described operation.

  In order to solve the above-described problems, the present invention provides a tension applying body that applies tension to an endless belt by pressing, and an urging means that exerts an urging force for urging the tension applying body in the belt pressing direction. In the belt apparatus having the above-described configuration, a locking unit that locks the tension applying body or the holding body that holds the tension applying body so as not to be moved by the urging force is provided.

  According to the present invention, there is an excellent effect that the labor of the operator when removing the endless belt can be reduced.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating an image forming unit of the printer. FIG. 3 is a perspective view showing a part of a belt device that exhibits a driving force for bringing a transfer belt and a secondary transfer roller between the printers apart from each other together with a secondary transfer roller and the like. FIG. 3 is a side view showing a secondary transfer nip of the printer and its surroundings. The perspective view which shows the belt holding mechanism of the belt apparatus of the printer. The perspective view which shows the supporting member of the belt holding mechanism. The perspective view which shows the rotation member of the belt holding mechanism. The perspective view which shows the tension arm of the belt holding mechanism. The side view which shows a belt holding mechanism. Sectional drawing which shows a part of tension arm fastened mutually by the locking bolt locking nut of the belt holding mechanism, and a part of rotation member. The side view which shows the belt holding mechanism at the time of replacement | exchange of a timing belt. FIG. 9 is a partial perspective view showing a part of a rotating member in a belt holding mechanism of a printer according to a first modification. The side view which shows the belt holding mechanism of the printer which concerns on a 2nd modification. The fragmentary perspective view which shows the edge part of the tension arm of the belt holding mechanism. The side view which shows the belt holding mechanism at the time of replacement | exchange of a timing belt.

Hereinafter, a printer for forming an image by an electrophotographic method will be described as an embodiment of an image forming apparatus to which the present invention is applied.
First, a basic configuration of the printer according to the embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating a printer according to an embodiment. This printer has an intermediate transfer belt 51 as an image carrier. Further, four image forming units 1Y, 1M, 1C, and 1K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images run on the intermediate transfer belt 51. It also has a tandem imaging unit arranged along the surface.

  The image forming units 1Y, 1M, 1C, and 1K have photoreceptors 11Y, 11M, 11C, and 11K. The photoconductors 11Y, 11M, 11C, and 11K are optically scanned by laser light emitted from the optical writing unit 80, and an electrostatic latent image is written thereon.

  The optical writing unit 80 emits laser light from the laser diode based on image information sent from an external device such as a personal computer. Specifically, the laser light L emitted from the light source is polarized in the main scanning direction by a polygon mirror that is rotationally driven by a polygon motor, and the photosensitive members 11Y, 11M, 11C, and 11K are passed through a plurality of optical lenses and mirrors. Irradiate the surface. Instead of the sulfur-based optical writing unit 80, an apparatus that performs optical scanning with LED light emitted from a plurality of LEDs of the LED array may be employed.

  The electrostatic latent images written in the image forming units 1Y, 1M, 1C, and 1K are developed by Y, M, C, and K developing devices, which will be described later, to become Y, M, C, and K toner images.

  Below the image forming units 1Y, 1M, 1C, and 1K, a transfer unit 50 is disposed as a transfer unit that moves the endless intermediate transfer belt 51 endlessly in the counterclockwise direction in the drawing. . In addition to the intermediate transfer belt 51, the transfer unit 50 includes a drive roller 52, a secondary transfer counter roller 53, a cleaning backup roller 54, four primary transfer rollers 55, a secondary transfer roller 56, a belt cleaning device 57, and the like. is doing. It also has a roller cleaning device 58 and the like.

  The intermediate transfer belt 51 is stretched by a driving roller 52, a secondary transfer counter roller 53, a cleaning backup roller 54, and four primary transfer rollers 55Y, 55M, 55C, and 55K disposed inside the loop. . Then, it is endlessly moved in the counterclockwise direction in the figure by the rotational force of the driving roller 52 that is driven to rotate counterclockwise in the figure by the driving means.

  The primary transfer rollers 55Y, 55M, 55C, and 55K sandwich the intermediate transfer belt 51 that is moved endlessly between the photoreceptors 11Y, 11M, 11C, and 11K. As a result, primary transfer nips for Y, M, C, and K where the front surface of the intermediate transfer belt 51 and the photoconductors 11Y, 11M, 11C, and 11K abut are formed.

  A primary transfer bias is applied to each of the primary transfer rollers 55Y, 55M, 55C, and 55K by a primary transfer power source. As a result, a primary transfer electric field is formed between the photoconductors 11Y, 11M, 11C, and 11K and the intermediate transfer belt 51. The Y, M, C, and K toner images on the photoreceptors 11Y, 11M, 11C, and 11K are primarily transferred onto the intermediate transfer belt 51 by the action of the primary transfer electric field and nip pressure. As a result, a four-color superimposed toner image is formed on the intermediate transfer belt 51.

  In the case of forming a monochrome image, the printer moves a support plate that supports primary transfer rollers 55Y, 55M, and 55C for Y, M, and C in the transfer unit 50. Thus, the intermediate transfer belt 51 is moved away from the photoconductors 11Y, 11M, and 11C by moving the primary transfer rollers 55Y, 55M, and 55C away from the photoconductors 11Y, 11M, and 11C and changing the stretching posture of the intermediate transfer belt 51. Separate. However, the primary transfer nip for K is maintained by continuously contacting the photosensitive member 11K with the intermediate transfer belt 51. In this state, of the four image forming units 1Y, 1M, 1C, and 1K, only the image forming unit 1K is driven to form a K toner image on the photoconductor 11K.

  The secondary transfer roller 56 of the transfer unit 50 is disposed outside the loop of the intermediate transfer belt 51, and the intermediate transfer belt 51 is sandwiched between the secondary transfer opposing roller 53 inside the loop. As a result, a secondary transfer nip where the front surface of the intermediate transfer belt 51 and the secondary transfer roller 56 abut is formed.

  While the secondary transfer roller 56 is electrically grounded, a secondary transfer bias output from the secondary transfer power source 200 is applied to the secondary transfer counter roller 53. As a result, a secondary transfer electric field for electrostatically moving the toner from the secondary transfer counter roller 53 side to the secondary transfer roller 56 side is formed between the secondary transfer counter roller 53 and the secondary transfer roller 56. The Note that a secondary transfer bias may be applied to the secondary transfer roller 56 and the secondary transfer counter roller 53 may be electrically grounded.

  Below the transfer unit 50, a paper feed cassette 100 that stores a plurality of recording sheets P in a bundle of sheets is disposed. In the paper feeding cassette 100, a paper feeding roller 101 is brought into contact with the uppermost recording sheet P of the paper bundle, and the recording sheet P is fed to the paper feeding path by being rotated at a predetermined timing. Send it out.

  A registration roller pair 102 is disposed near the end of the paper feed path. The registration roller pair 102 immediately stops the rotation of both rollers when the recording sheet P fed from the paper feeding cassette 100 is sandwiched between the rollers. Then, at a timing at which the sandwiched recording sheet P can be synchronized with the toner image on the intermediate transfer belt 51 in the secondary transfer nip, the rotational driving of both rollers of the registration roller pair 102 is resumed, and the recording sheet P is Send to the transfer nip.

  The four-color superimposed toner image on the intermediate transfer belt 51 brought into close contact with the recording sheet P at the secondary transfer nip is secondarily transferred collectively onto the recording sheet P by the action of a secondary transfer electric field or nip pressure. The recording sheet P having the full-color toner image or the monochrome toner image formed on the surface in this way is separated from the secondary transfer roller 56 and the intermediate transfer belt 51 by the curvature when passing through the secondary transfer nip.

  A fixing device 90 is disposed on the right side of the secondary transfer nip in the drawing. The fixing device 90 forms a fixing nip with a fixing roller 91 containing a heat source such as a halogen lamp and a pressure roller 92 that rotates while contacting with the fixing roller 91 with a predetermined pressure. The recording sheet that has passed through the secondary transfer nip is fed into the fixing device 90 and is sandwiched between the fixing nips in such a posture that the unfixed toner image carrying surface is in close contact with the fixing roller 91. Then, the toner in the toner image is softened by the influence of heating and pressurization, and a full-color image or a monochrome image is fixed. The recording sheet P discharged from the fixing device 90 is discharged to the outside of the apparatus through the post-fixing conveyance path.

  On the surface of the intermediate transfer belt 51 after passing through the secondary transfer nip, a small amount of transfer residual toner that has not been secondarily transferred to the recording sheet P, paper dust, and the like are adhered. They are removed from the surface of the intermediate transfer belt 51 by a belt cleaning device 57.

  Dirt such as paper dust or scattered toner adheres to the surface of the secondary transfer roller 56 after passing through the secondary transfer nip. They are removed from the surface of the secondary transfer roller 56 by a roller cleaning device 58.

  Since the image forming units 1Y, 1M, 1C, and 1K have the same configuration except that the colors of the toners used are different from each other, only one image forming unit 1 is attached to the end of the reference numeral hereinafter. In the following description, the subscripts (Y, M, C, K) of the colors are omitted.

  FIG. 2 is a schematic configuration diagram showing the image forming unit 1. The image forming unit 1 configured to be detachable from the printer main body includes a charging device 21, a developing device 31, a cleaning device 41, and the like in addition to the drum-shaped photoconductor 11 serving as a latent image carrier.

  The photoconductor 11 has an organic photosensitive layer formed on the surface of a drum-shaped substrate, and is driven to rotate in the clockwise direction in the drawing by a driving means.

  The charging device 21 generates a discharge between the charging roller and the photosensitive member 11 while bringing a charging roller to which a charging bias is applied into contact with or close to the photosensitive member 11, so that the surface of the photosensitive member 11 is normally charged with toner. Charge uniformly to the same negative polarity as the polarity. As the charging bias, a superposition of a DC voltage and an AC voltage is employed. Note that a method using a charging charger may be adopted instead of the method using a charging roller.

  The developing device 31 includes a developing sleeve 31a that is a developer carrying member and two screw members 31b and 31c that convey the developer while stirring in a storage container that stores a developer containing toner and a magnetic carrier. is doing. As the developing device 31, it is possible to employ a developing device that uses a one-component developer containing toner particles as a main component without including a magnetic carrier.

  A cleaning device 41 that cleans the surface of the photoconductor 11 after passing through the primary transfer nip includes a cleaning blade 41a that is a cleaning member and a cleaning brush roller 41b. The cleaning blade 41 a is in contact with the surface of the photoconductor from the counter direction with respect to the rotation direction of the photoconductor 11. Further, the cleaning brush roller 41 b is in contact with the surface of the photoconductor while rotating in the direction opposite to the rotation direction of the photoconductor 11. Then, the surface of the photoreceptor is cleaned by the cleaning blade 41a and the cleaning brush roller 41b.

  In this printer, it is possible to execute a shock cancellation operation for reducing shock jitter as necessary. When the recording sheet P enters or exits the secondary transfer nip, the shock jitter applies a load to the intermediate transfer belt 51 or the secondary transfer roller 56 to temporarily and rapidly increase the linear speed of the intermediate transfer belt 51. It is a phenomenon that decreases or increases. This is a phenomenon that easily occurs when a relatively thick recording sheet P is used. When the shock jitter occurs, image density unevenness is generated in synchronization therewith, which is not preferable.

  FIG. 3 is a perspective view showing a part of the belt device 150 that exerts a driving force for contacting and separating the intermediate transfer belt 51 and the secondary transfer roller 56 together with the secondary transfer roller 56 and the like. The secondary transfer roller 56 and the secondary transfer counter roller 53 disposed above the secondary transfer roller 56 are opposed to each other with the intermediate transfer belt 51 interposed therebetween. A biasing force applied to the secondary transfer counter roller 53 is applied to the secondary transfer roller 56 by a spring 67.

  The belt device 150 constituted by a stepping motor 155 or the like rotates the eccentric cam 61 to move the secondary transfer roller 56 closer to or away from the secondary transfer counter roller 53. The eccentric cam 61 is provided coaxially with the secondary transfer counter roller 53 at each of both axial ends of the secondary transfer counter roller 53.

  Ball bearings 62 are attached to both ends of the secondary transfer roller 56 in the axial direction so as not to prevent the rotation of the secondary transfer roller 56, and the eccentric cam 61 is abutted against the ball bearing 62. ing. When the cam shaft 61a to which the eccentric cam 61 is attached is rotated by the rotational driving force from the belt device 150, the eccentric cam 61 and the cam shaft 61a are D-cut so that the eccentric cam 61 also rotates at the same timing and at the same angle. It is fitted with a groove or the like.

  As a shape of the eccentric cam 61, a portion where the distance between the rotation center of the eccentric cam 61 and the outer shape portion is the shortest is shorter than the diameter of the secondary transfer counter roller 53. Further, the longest distance connecting the rotation center of the eccentric cam 61 and the outer shape portion is longer than the diameter of the secondary transfer counter roller 53.

  The rotation of the cam shaft 61a is controlled by the belt device 150. The belt device 150 transmits the rotational driving force of the driving pulley 153 disposed in the loop of the timing belt 151 that is an endless belt to the driven pulley 152 disposed in the loop. Then, the rotational driving force of the driven pulley 152 is transmitted to the eccentric cam 61.

  The eccentric cam 61 is abutted against the ball bearing 62, and the secondary transfer roller 56 is pushed down in the direction of separating from the intermediate transfer belt 51 against the urging force of the spring 67 by its forward rotation. Thereby, the gap amount between the intermediate transfer belt 51 and the secondary transfer roller 56 shown in FIG. 4 is increased. Further, the secondary transfer roller 56 is moved in the same direction as the urging force of the spring 67 by reverse rotation, thereby reducing the gap amount.

  In the shock canceling operation, the belt device 150 causes the intermediate transfer belt 51 and the secondary transfer roller 56 to be separated from each other when the sheet enters the secondary transfer nip, so that the impact when the sheet enters and the process linear velocity of the intermediate transfer belt 51 are increased. Suppress fluctuations (speed fluctuations). Similarly, when the recording sheet P comes out of the secondary transfer nip, the eccentric cam 61 is rotated by the belt device 150 so that the rear end of the recording sheet P passes through the secondary transfer roller 56 before passing through the secondary transfer nip. The intermediate transfer belt 51 is separated. As a result, the impact when the recording sheet P leaves the secondary transfer nip is also reduced.

Next, a characteristic configuration of the printer will be described.
FIG. 5 is a perspective view showing the belt holding mechanism 170 of the belt device (150). In the drawing, an idler pulley 154, a driven pulley 152, and a driving pulley 153 are disposed in the loop of the timing belt 151. The driven pulley 152 is rotatably held by a cam shaft (61a in FIG. 3).

  The driving pulley 153 is fixed to the motor shaft of the stepping motor (155) fixed to the main body side plate of the belt holding mechanism 170.

  Around the timing belt 151, a support member 156, a rotating member 157 that is a rotating body, and a tension arm 158 that is a holding body are disposed.

  FIG. 6 is a perspective view showing the support member 156. FIG. 7 is a perspective view showing the rotating member 157. FIG. 8 is a perspective view showing the tension arm 158. Hereinafter, the configuration of the belt holding mechanism 170 will be described with reference to FIGS.

  A support member 156 formed by bending a sheet metal is fixed to the main body of the belt holding mechanism 170, and a rotation shaft 159 is bridged between two opposing side plates (see FIG. 6). Also, a female screw hole 156a as a female screw is formed in the top plate that connects the two side plates.

  A rotating member 157 formed by bending a sheet metal has a hole 157b through which the rotating shaft 159 supported by the support member 156 passes through each of the two side plates facing each other. In a state where the rotation shaft 159 is passed through the two holes 157b, it is possible to rotate about the rotation shaft 159.

  A long hole 157a is formed on one side (right end side in the figure) of the rotating member 157 with the through hole as a boundary. Further, a bolt hole 157c is formed in the top plate that connects the two side plates so as to allow the bolts to pass therethrough. The role of the long hole 157a will be described later.

  In FIG. 7, the idler pulley 154 is shown together with the rotating member 157. The idler pulley 154 rotates on an axis fixed to the rotating member 157.

  The tension arm 158 shown in FIG. 8 has side plates 158c and 158d facing each other, and a bottom plate 158e connecting them. The bottom plate 158e is provided with a large opening, and the timing belt 151 is passed through the opening (see FIG. 5).

  A side plate 158c and a side plate 158d of the tension arm 158, which are formed by bending a sheet metal, have a hole 158a for allowing the rotation shaft 159 supported by the support member 156 to pass therethrough. In a state where the rotation shaft 159 is passed through the two holes 158a, it is possible to rotate about the rotation shaft 159.

  The side plate 158c and the side plate 158d of the tension arm 158 rotatably hold a tightener 161 as a tension applying body. Further, an elongated hole 158f is formed in the side plate 158d. The role of the long hole 158f will be described later.

  In FIG. 5, the rotation member 157 and the tension arm 158 can rotate independently of each other about the rotation shaft 159. The support member 156 supports both the rotating member 157 and the tension arm 158.

  Hereinafter, in order to facilitate visual understanding, the support member 156, the rotation member 157, and the tension arm 158 are deformed and illustrated.

  FIG. 9 is a side view showing the belt holding mechanism 170. In the figure, only the top plate is shown for the support member 156 for easy understanding. Further, the tension arm 158 is shown as a rectangular shape in the subsequent drawings for easy understanding.

  The rotating shaft 159 is supported by the support member 156 as described above. The bolt 163 passes through a bolt hole 157c (see FIG. 7) provided in the top plate of the rotating member 157 and is screwed into a female screw hole 156a (see FIG. 6) provided in the top plate of the support member 156. Thus, the rotation member 157 is screwed to the support member 156. By this screwing, the rotation of the rotation member 157 around the rotation shaft 159 is prevented. The bolt hole 157c, the female screw hole 156a, and the bolt 163 function as a rotation prevention unit that prevents the rotation of the rotation member 157.

  Hereinafter, with respect to the rotating member 157 and the tension arm 158, the left side in the drawing with the rotating shaft 159 as a boundary is referred to as one end side, and the right side in the drawing is referred to as the other end side.

  The torsion spring 162 as an urging means is held by the rotating shaft 159 with the rotating shaft 159 passing through the coil portion. In this state, one arm portion urges one end side of the tension arm 158 as a holding body in the direction of arrow B in the drawing, and the other arm portion pushes one end side of the rotating member 157 as a rotating body in the drawing to arrow A. Energized in the direction. That is, the torsion spring 162 urges the tension arm 158 and the rotation member 157 in a direction in which the angle formed by one end side of the tension arm 158 and the one end side of the rotation member 157 around the rotation shaft 159 is increased. . However, in the state shown in the drawing, the rotation member 157 is prevented from rotating by the rotation preventing means including the bolt 163 or the like, so that only the tension arm 158 is centered on the rotation shaft 159 by the urging force of the torsion spring 162. And tries to rotate in the direction of arrow B. Then, the tighter 161 held by the tension arm 158 comes into contact with the timing belt 151 from the surface side and presses the timing belt 151 in the direction of arrow C in the figure toward the inside of the loop. By this pressing, tension is applied to the timing belt 151.

  When the timing belt 151 is tensioned with a predetermined tension, the urging force of the torsion spring 162 balances with the force that the timing belt 151 tries to push back the tighter 161 in the direction opposite to the arrow C direction in the figure.

  The elongated hole 158f provided in the tension arm 158 and the elongated hole 157a provided in the rotating member 157 are opposed to each other in the axial direction of the rotating shaft 159 as illustrated.

  FIG. 10 is a cross-sectional view showing a part of the tension arm 158 and a part of the rotating member 157 that are fastened to each other by a locking bolt 164 that is a male screw and a locking nut 165 that is a female screw. In the figure, the locking bolt 164 is screwed with a locking nut 165 in a state where the locking bolt 164 is passed through the elongated hole 158f of the tension arm 158 and the elongated hole 157a of the rotating member 157. The tension arm 158 and the rotating member 157 are fastened to each other by this screw. In this state, the tension arm 158 urged in the urging direction by the torsion spring 162 shown in FIG. 9 is locked so as not to rotate in the urging direction. That is, the locking bolt 164 and the locking nut 165 function as locking means that locks the tension arm 158 so that the tension arm 158 is not rotated in the urging direction (direction of arrow B in FIG. 9) by the torsion spring 162.

  As shown in FIG. 9, when the tension arm 158 is not locked by the locking bolt (164) and the locking nut 165, the tighter 161 is pressed against the timing belt 151 by the urging force of the torsion spring 162. . Thereby, tension is applied to the timing belt 171. At this time, the timing belt is stretched with a tension corresponding to the urging force of the torsion spring 162. Even if the locking bolt 164 and the locking nut 165 are attached in this state and the rotation of the tension arm 158 is locked, the tension of the timing belt 151 is not changed. Therefore, the operation may be performed with the locking bolt 164 and the locking nut attached, or without the attachment, the timing belt 151 may be stretched with a predetermined tension by the urging force of the torsion spring 162.

  FIG. 11 is a side view showing the belt holding mechanism 170 when the timing belt 151 is replaced. When the timing belt 151 is replaced, as shown in the drawing, the rotating member 157 and the tension arm 158 are fastened by the locking bolt 164 and the locking nut 165. Thus, the tension arm 158 is locked to the rotating member 157 so as not to be rotated by the urging force of the torsion spring 162. Then, by removing the bolt 163 from the support member 156, the rotation member 157 and the tension arm 158 are integrally rotated about the rotation shaft 159. At this time, since the rotation of the tension arm 158 independent of the rotation member 157 due to the urging force of the torsion spring 162 is prevented by the locking bolt 164 and the locking nut 165, the urging force is applied to the operator's hand. There is no transmission. Since the timing belt 151 exerts a force that pushes back the tighter 161, the operator can rotate the rotating member 157 and the tension arm 158 integrally without using a strong force to separate the tightner 161 from the timing belt 151. Can do. Thereby, the timing belt 151 can be detached from the three pulleys (152, 153, 154) by substantially eliminating the tension of the timing belt 151.

  The idler pulley 154 plays a role of increasing the slack of the timing belt 151 when the tighter 161 is separated from the timing belt 151. By increasing the slack, the timing belt 151 can be attached and detached more easily.

  Next, modified examples in which a part of the configuration of the printer according to the embodiment is modified to another configuration will be described. Unless otherwise specified below, the configuration of the printer according to the modification is the same as that of the embodiment.

[First modification]
FIG. 12 is a partial perspective view showing a part of the rotating member 157 in the belt holding mechanism (170) of the printer according to the first modification. The rotating member 157 is not provided with a long hole for allowing the locking bolt to pass therethrough. Instead, as shown in the figure, the male screw 166 is fixed to the surface of the rotating member 157 main body by welding. The male screw 166 is passed through the elongated hole (158f) of the tension arm (158), and the locking nut (165) is screwed to the fastening member 157 and the tension arm (158).

  In such a configuration, when the timing belt (151) is removed. The work of passing the locking bolt through the long hole can be omitted, and the removal workability can be improved.

  Instead of fixing the male screw 166 to the rotating member 157, the male screw 166 may be fixed to the tension arm (158) and passed through the elongated hole (158a) of the rotating member 157.

[Second modification]
FIG. 13 is a side view showing the belt holding mechanism 170 of the printer according to the second modification. The belt holding mechanism 170 does not have a rotating member. The tension arm 158, which is a holding body, can be rotated about a rotation shaft 159. However, in the state shown in the drawing, one end side is fixed to the support member 156 by a bolt 163 that is a rotation prevention means. The movement is blocked.

  A tighter holding shaft 169 as a holding body for holding the tighter 161 passes through the long hole 158f of the tension arm 158 as the second holding body, and is held by the tension arm 158 so as to slide in the long hole 158f. Yes. A non-rotatable spring holding shaft 167 is fixed to the tension arm 158. The end of the spring holding shaft 167 and the tighter holding shaft 169 are connected by a coil spring 168 as urging means. The direction in which the tighter holding shaft 169 slides in the elongated hole 158f of the tension arm 158 is along the pulling direction (the biasing direction, arrow D direction in the figure) of the coil spring 168.

  In the drawing, only one end side in the longitudinal direction of the tighter holding shaft 169 is drawn, but the tighter holding shaft 169 is pulled by the coil spring 168 in the same manner on the other end side. By this pulling, the tensioner 161 abuts against the front surface of the timing belt 151 and presses the timing belt 151, thereby applying tension to the timing belt 151.

  FIG. 14 is a partial perspective view showing an end portion of the tension arm 158. Both ends of the tighter holding shaft 169 are male threads (hereinafter referred to as shaft end male threads). A locking nut 165 is screwed to each shaft end male screw. During normal operation, the screw of the locking nut 165 for each shaft end screw is loosened, so that the tighter holding shaft 169 can freely slide within the elongated hole 158f. For this reason, it is pulled in the direction of arrow D by the coil spring 168, and the tighter 161 presses the timing belt 151.

  When the timing belt 151 is removed, the locking nuts 165 screwed to the respective shaft end male threads 1a at both ends of the tighter holding shaft 169 are tightened so that the distance between them is reduced. As a result, the tighter 161 and the tighter holding shaft 169 are locked to the tension arm 158 so as not to slide in the elongated hole 158f.

  FIG. 15 is a side view showing the belt holding mechanism 170 when the timing belt 151 of the printer according to the second modification is replaced. The operator who has locked the tighter holding shaft 169 to the tension arm 158 as described above removes the bolt 163 from the support member and rotates the tension arm 158 about the rotation shaft 159. At this time, the sliding movement of the tighter holding shaft 169 due to the pulling force (biasing force) of the coil spring 168 is blocked by the shaft end male screw and the locking nut 165, so that the urging force is transmitted to the operator's hand. There is no. Since the timing belt 151 exerts a force to push the tighter 161 back, the operator can rotate the tension arm 158 and separate the tighter 161 from the timing belt 151 without using a strong force. Thereby, the timing belt 151 can be detached from the three pulleys (152, 153, 154) by substantially eliminating the tension of the timing belt 151.

  Further, since the printer according to the second modification is not provided with the rotating member, the cost can be reduced.

  So far, the belt device 150 having the endless belt timing belt 151 has been described. However, the present invention is also applicable to belt devices having other endless belts such as an intermediate transfer belt, a photosensitive belt, a developing belt, and a sheet conveying belt. Is possible.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
[First aspect]
In the first aspect, a tension applying body (for example, a tensioner 161) that applies tension to an endless belt (for example, the timing belt 151) and a holding body (for example, a tension arm 158 or a tensioner holding shaft 169) that holds the tension applying body. And a biasing means for biasing the holding body in the belt pressing direction (for example, a torsion spring 162, a coil spring 168), and a biasing force by the biasing means. And a locking means (for example, a locking bolt 164, a locking nut 165, and a shaft end male screw) for locking so as not to move.

  In the first aspect, after the movement of the holding body due to the urging force of the urging means is locked by the locking means, the holding body is moved in the direction to release the tension of the endless belt, and the tension applying body, the locking means, and the urging means. Move with. In this movement, not only the operator but also the tension applying body, the locking means, and the biasing means are moved together, so that the locking of the holding body in the biasing direction by the locking means can be continued. Therefore, the urging force by the urging means is not exerted on the operator's hand, and the labor of the operator when removing the endless belt can be reduced.

[Second embodiment]
A second aspect is the first aspect, wherein the holding body is configured to be rotatable about a rotation axis (for example, the rotation axis 159), and is configured to be rotatable about the rotation axis ( For example, a rotation member 157) and rotation prevention means (for example, a bolt 163 and a support member 156) for preventing rotation of the rotation body are provided, and one end side of the holding body around the rotation axis and the The urging means (for example, the torsion spring 162) is urged so as to urge the holding body and the rotating body in a direction (for example, the direction of arrow A or B in FIG. 9) to widen the angle formed with one end of the rotating body. The locking means (for example, the locking bolt 164 and the locking nut 165) is configured to lock the movement of the holding body by fastening the holding body and the rotating body so as not to change the angle. ).

  In the second aspect, in a state where the holding body and the rotating body are fastened by the locking means, after the rotating body is released from the rotation blocking by the rotation blocking means, the holding body and the rotating body around the rotating shaft. , And the tension applying body held by the holding body is separated from the endless belt. Then, the endless belt whose tension is eliminated by the separation is removed from the belt device. During this series of operations, it is not necessary to push down the tension applying body or the holding body against the urging force of the urging means, so that the labor of the operator when removing the endless belt can be reduced. it can.

[Third Aspect]
A third aspect is the second aspect, in which the holes (for example, the long holes 157a and 158f) through which the male screws (for example, the locking bolts 164) are passed are the other end side opposite to the one end side of the rotating body, And the male screw that passes through the hole of the rotating body and the hole of the holding body, and a female screwed to the hole. A screw (for example, a locking nut 165) is used.

  In the third aspect, the holding body can be locked to or released from the rotating body by a simple operation of tightening or loosening the female screw.

[Fourth aspect]
According to a fourth aspect, in the second aspect, a male screw is provided on any one of the other end side opposite to the one end side of the rotating body and the other end side opposite to the one end side of the holding body. (For example, a male screw 166) is provided with a hole (for example, a long hole 157a) through which the male screw is fixed to the other, and the male screw and a female screw screwed to the male screw are used as the locking means. It is a feature.

  In the fourth aspect, the holding body can be locked to the rotating body or unlocked by a simple operation of tightening or loosening the female screw. Further, unlike the third aspect, when removing the endless belt, the work of passing the male screw through the hole of the rotating body or the holding body can be omitted.

[Fifth aspect]
The fifth aspect is the second, third, or fourth aspect, in which a support body (for example, a support member 156) that supports the rotating body is provided, and the rotating body is screwed to the support body as the rotation preventing means. It is characterized by using a screwing means (for example, a bolt 163).

  In the fifth aspect, the rotation of the rotating body can be prevented or the rotation prevention can be released by a simple operation such as screwing or unscrewing.

[Sixth aspect]
A sixth aspect is the second, third, fourth, or fifth aspect, wherein a torsion spring (for example, a torsion spring 162) is used as the biasing means, and a coil portion of the torsion spring is passed through the rotating shaft, whereby the torsion spring The one end of the holding body is urged by one of the arm portions, and the one end side of the rotating body is urged by the other arm portion of the torsion spring. .

  In the sixth aspect, using the torsion springs that are widely available in the market, the holding body and the rotating body in a direction that widens the angle formed by one end side of the holding body around the rotating shaft and one end side of the rotating body. By energizing, cost can be reduced.

[Seventh aspect]
A seventh aspect is the first aspect, wherein the holding body (for example, the tighter holding shaft 169) can be rotated about a rotation shaft (for example, the rotation shaft 159) and the urging means (for example, the coil spring 168). ) And a second holding body (for example, a tension arm 158) that is movably held in an urging direction (for example, the direction of arrow D in FIG. 13), and a rotation blocking means (for example, a bolt) that prevents the second holding body from rotating 163), and the locking means (eg, shaft end male screw and locking nut 165) is configured to lock the movement of the holding body in the biasing direction on the second holding body. It is characterized by that.

  In the seventh aspect, in a state where the sliding movement of the holding body on the second holding body is locked by the locking means, the second holding body is released from the rotation blocking by the rotation blocking means, and then the rotation shaft The second holding body is rotated around the center to separate the tension applying body from the endless belt. Then, the endless belt whose tension is eliminated by the separation is removed from the belt device. During this series of operations, the urging force of the urging means is not exerted on the operator's hand, so that the labor of the operator when removing the endless belt can be reduced.

[Eighth aspect]
The eighth aspect is the second, third, fourth, fifth or sixth aspect, wherein the endless belt is driven from a driving pulley (for example, a driving pulley 153) disposed inside the loop. The driving force is transmitted to a pulley (for example, the driven pulley 152). With such a configuration, it is possible to reduce the labor of the operator when removing the endless belt from the belt device as the drive transmission means.

[Ninth aspect]
The ninth aspect is characterized in that an idler pulley is provided on the rotating body separately from the driven pulley. In such a configuration, when the rotating member is rotated to remove the endless belt, the attitude of the endless belt is changed from the attitude when the endless belt is driven. By such a change in posture, the endless belt can be further loosened to improve the workability of attaching and detaching the endless belt.

[Tenth aspect]
According to a tenth aspect, in an image forming apparatus (for example, a printer) including a belt device that moves an endless belt endlessly, the first, second, third, fourth, fifth, sixth, seventh, The eighth or ninth aspect is used.

152: Driven pulley 153: Driven pulley 154: Idler pulley 159: Rotating shaft 150: Belt device 151: Timing belt (endless belt)
156: Support member (a part of rotation prevention means, support)
157: Rotating member (rotating body)
157a: long hole (hole)
158: Tension arm (holding body, second holding body)
158f: Long hole (hole)
161: Tightener (tensioner);
162: Torsion spring (biasing means)
164: Locking bolt (part of locking means, male screw)
165: Locking nut (part of locking means, female screw)
166: Male screw 163: Bolt (part of rotation prevention means, screw fixing means)
165: Locking nut (part of locking means)
168: Coil spring (biasing means)
169: Tightener holding shaft (holding body)

Japanese Patent No. 3422543

Claims (10)

In a belt device having a tension applying body that applies tension to an endless belt, a holding body that holds the tension applying body, and an urging unit that urges the holding body in a belt pressing direction.
A belt device comprising a locking means for locking the holding body so as not to be moved by the urging force of the urging means. The belt device according to claim 1.
The holding body is configured to be rotatable around a rotation axis,
A rotating body configured to be rotatable about the rotating shaft, and a rotation preventing means for preventing rotation of the rotating body;
The urging means is configured to urge the holding body and the rotating body in a direction in which an angle formed by one end side of the holding body and one end side of the rotating body with respect to the rotating shaft is widened. ,
The belt device is characterized in that the locking means is configured to lock the movement of the holding body by fastening the holding body and the rotating body so as not to change the angle. The belt device according to claim 2.
A hole through which a male screw is passed is provided on the other end side opposite to the one end side of the rotating body, and the other end side opposite to the one end side of the holding body,
A belt device using the male screw penetrating through the hole of the rotating body and the hole of the holding body and a female screw screwed to the hole as the locking means. The belt device according to claim 2.
A hole through which a male screw penetrates is provided in one of the other end side opposite to the one end side of the rotating body and the other end side opposite to the one end side of the holding body, A belt device, wherein a screw is fixed to the other, and the male screw and a female screw screwed on the male screw are used as the locking means. The belt device according to claim 2, 3 or 4,
Providing a support for supporting the rotating body;
A belt device using screwing means for screwing the rotating body to the support as the rotation preventing means. The belt device according to claim 2, 3, 4 or 5,
Using a torsion spring as the biasing means,
The coil portion of the torsion spring is passed through the rotating shaft, the one end portion of the holding body is urged by one arm portion of the torsion spring, and the other arm portion of the torsion spring is used to bias the rotating body. A belt device characterized in that the one end side is biased. The belt device according to claim 1.
A second holding body which is rotatable about a rotation axis and which holds the holding body so as to be movable in a biasing direction by the biasing means;
A rotation preventing means for preventing rotation of the second holding body;
The belt device according to claim 1, wherein the locking means is configured to lock the movement of the holding body in the urging direction on the second holding body. The belt device according to claim 2, 3, 4, 5 or 6,
A belt device characterized in that the endless belt transmits a driving force from a driving pulley disposed inside the loop to a driven pulley. The belt device according to claim 8, wherein
In addition to the driven pulley, an idler pulley is provided on the rotating body. In an image forming apparatus including a belt device that moves an endless belt endlessly,
An image forming apparatus using the belt device according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9 as the belt device.

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