JP2015018125A - Image forming unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in quality of printed images.SOLUTION: An image forming unit of the present invention includes a rotatable rotating body, a coupling that receives the driving force of the rotating body, a torsion spring that is attached to the coupling so as to fasten an annular part, a rotation regulating unit that regulates the rotation of the torsion spring when the rotating body rotates with the coupling, and a rewind regulating unit that is arranged opposite to the outer surface of the annular part of the torsion spring and regulates the rewind of the torsion spring when the rotation of the torsion spring is regulated by the rotation regulating unit. With this configuration, the rewind of the torsion spring is securely regulated from the outer surface side of the annular part by the rewind regulating unit, while the rotation of the torsion spring is regulated by the rotation regulating unit, so as to regulate the fastening force of the torsion spring, and thereby securely preventing a change in the rotation speed of the rotating body due to a change in load applied by the torsion spring to the rotating body together with the coupling, and preventing deterioration in quality of printed images.

Description

  The present invention relates to an image forming unit and an image forming apparatus, and is suitable for application to, for example, an electrophotographic printer (hereinafter also referred to as a printer).

  The conventional printer forms a toner image on the surface of the photoconductive drum while rotating the photoconductive drum provided in the toner cartridge by the driving force of the motor, and transfers the toner image to the surface of the recording paper. A printed image is formed on the surface of the recording paper.

  However, in the printer, an external force other than the driving force of the motor is applied to the photoconductive drum by pressing a developing roller, a cleaning blade, etc., and the rotational speed of the photoconductive drum (hereinafter referred to as this) is formed when a printed image is formed. When the drum rotation speed is changed by an external force, a toner image formation failure occurs, and as a result, the quality of the printed image deteriorates.

  For this reason, the printer fixes a gear to one end of the shaft of the photoconductive drum and attaches a coil spring to the central stud of the gear via two washers having a small friction coefficient, so that one washer is attached to the side wall of the gear. And one end of the coil spring is in contact with the other washer.

  When the printer rotates the gear together with the photoconductive drum according to the operation of the motor during image formation, the other end of the coil spring is separated from the side wall of the gear via one washer. The toner cartridge is rewound while being engaged with a ridge provided on the toner cartridge.

  In this way, the printer applies a load to the photoconductive drum that rotates in accordance with the driving of the motor by the coil spring during image formation (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-102097 (7th page, 8th page, FIGS. 10 to 14)

  However, in the conventional printer, one end of the coil spring is brought into contact with the other washer having a small friction coefficient. For this reason, in the printer, when the image is formed, the coil spring slides with respect to the other washer and the load applied to the photoconductive drum may change with the rotation speed of the drum. There is still a problem that it is still insufficient to prevent the deterioration of quality.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an image forming unit and an image forming apparatus capable of preventing deterioration of the quality of a printed image.

  In order to solve such a problem, in the present invention, a rotating body that is provided so as to be rotatable in a predetermined rotating direction via a rotating shaft and carries a developer for image formation on the surface, and a rotating body at one end of the rotating shaft. A coupling that receives a driving force, a torsion spring that is attached so as to tighten an annular portion on the coupling, a coupling that receives the driving force, and a rotating body together with the coupling. When rotating in the rotation direction, the rotation restricting portion that restricts the rotation of the torsion spring in the rotation direction and the outer surface of the annular portion of the torsion spring are arranged opposite to each other, and the rotation restricting portion restricts the rotation of the torsion spring. At this time, a rewinding restriction portion for restricting rewinding of the torsion spring is provided.

  Therefore, in the present invention, while the rotation of the torsion spring is restricted by the rotation restricting portion, the unwinding of the torsion spring can be reliably restricted from the outer surface side of the annular portion and the tightening force can be adjusted. As a result, the rotating body together with the coupling is rotated with a load applied by a torsion spring to cancel the external force, and the load is changed and the rotational speed of the rotating body is reliably prevented from changing. Can do.

  According to the present invention, a rotating body that is provided so as to be rotatable in a predetermined rotating direction via a rotating shaft and carries a developer for image formation on the surface, and rotates integrally with the rotating body at one end of the rotating shaft. A coupling that receives the driving force, a torsion spring that is attached to the coupling so as to tighten the annular portion, and the coupling receives the driving force, and the rotating body rotates in the rotation direction together with the coupling. When the torsion spring is disposed to face the outer surface of the annular portion of the torsion spring and the rotation restricting portion for restricting the rotation of the torsion spring in the rotation direction, And a rewinding restricting part that restricts the rewinding of the torsion spring. It is possible to adjust the tightening force by reliably regulating the unwinding of the spring from the outer surface side of the annular part. As a result, the rotating body together with the coupling is applied with a load by the torsion spring to cancel the external force The image forming unit and the image forming apparatus capable of reliably preventing the rotation speed of the rotating body from changing due to the rotation of the rotating body and thus preventing the deterioration of the quality of the printed image are realized. can do.

1 is a schematic side view illustrating a configuration of a color printer according to an embodiment. It is a rough-line perspective view which shows the external appearance structure (1) of a 1st image forming unit. It is a rough-line exploded perspective view which shows the external appearance structure (2) of a 1st image forming unit. FIG. 2 is a schematic side view showing an internal configuration of a first image forming unit. FIG. 6 is a schematic perspective view illustrating a configuration of a developing unit coupling provided in a right side frame of the developing unit. FIG. 3 is a schematic side view showing a configuration of a right end portion of the first image forming unit. It is a rough-line perspective view which shows the structure of a drive unit. FIG. 6 is a schematic perspective view for explaining the loading of the first image forming unit into the printer housing. It is a rough-line perspective view with which it uses for description of engagement with a drum unit drive part and a drum unit coupling. FIG. 6 is a schematic cross-sectional view for explaining the engagement between the drum unit driving unit and the drum unit coupling when the photosensitive drum rotates with a drum driving force. FIG. 6 is a schematic side view for explaining an external force applied to the photosensitive drum when rotating in one rotation direction. FIG. 6 is a schematic cross-sectional view for explaining the engagement between the drum unit driving unit and the drum unit coupling when the photosensitive drum rotates by receiving an acceleration external force together with the drum driving force. It is a rough-line perspective view which shows the structure (1) of a photosensitive drum. FIG. 6 is a schematic cross-sectional view showing a configuration (2) of the photosensitive drum. It is a rough-line disassembled perspective view which shows the structure (1) of a drum unit coupling. It is a rough-line perspective view which shows the structure (2) of a drum unit coupling. It is a rough-line perspective view which shows the structure of the rotation control part provided in the right side frame of the drum unit. FIG. 6 is a schematic side view for explaining the restriction of rotation of the torsion spring in one rotation direction by the rotation restriction unit when the photosensitive drum rotates in one rotation direction. It is a rough-line perspective view with which it uses for description of the spring winding direction at the time of attaching a torsion spring to a drum unit coupling. It is a rough-line side view which shows the structure of the rewinding control part provided in the cover. It is a rough-line side view with which it uses for description of the regulation of rewinding by the rewinding control part when the rotation to the one rotation direction of a torsion spring is controlled.

The best mode for carrying out the invention (hereinafter, also referred to as an embodiment) will be described below with reference to the drawings. The description will be given in the following order.
(1) Embodiment (2) Other embodiments

(1) Embodiment (1-1) Configuration of Color Printer In FIG. 1, reference numeral 1 denotes a color electrophotographic printer (hereinafter also referred to as a color printer) according to an embodiment as a whole. The color printer 1 includes, for example, a substantially box-shaped housing (hereinafter also referred to as a printer housing) 2 whose right end surface in the drawing is the front surface 2A.

  Incidentally, in the following description, the upper direction of the color printer 1 indicated by the arrow a1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the upward direction of the printer. The direction opposite to the upward direction of the printer is also referred to as the downward direction of the printer. When it is not necessary to distinguish between these, or when both are indicated, they are collectively referred to as the upward and downward direction of the printer.

  In the following description, the direction in front of the color printer 1 indicated by the arrow b1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the front direction of the printer. The direction opposite to the front direction of the printer is also referred to as the rear direction of the printer. When it is not necessary to distinguish between these directions or when both are indicated, they are collectively referred to as the front and rear direction of the printer.

  Furthermore, in the following description, the left direction of the color printer 1 indicated by the arrow c1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the printer left direction. The direction opposite to the left direction of the printer is also referred to as the right direction of the printer. When it is not necessary to distinguish between these, or when both are indicated, they are collectively referred to as the left and right direction of the printer.

  The printer housing 2 has a concave portion (hereinafter referred to as a recording paper receiving medium) on which a rectangular recording paper 5 serving as a medium having a printed image formed thereon is placed on the rear end of the upper surface 2B and delivered to the user. 2BX is also formed.

  Further, the printer housing 2 discharges the recording paper 5 for discharging the recording paper 5 on which the print image is formed from the inside of the printer housing 2 to the recording paper delivery section 2BX at a predetermined position on the rear inner wall of the recording paper delivery section 2BX. An outlet (not shown) is formed. Furthermore, the printer housing 2 is provided with a door (not shown) that can be opened and closed at the left end, for example.

  On the other hand, an image forming unit 7 for forming a color print image on the surface of the recording paper 5 (that is, printing a color image to be printed) is provided in the printer casing 2 from the center to the upper end. It has been.

  In the printer housing 2, a recording paper supply unit (hereinafter referred to as a paper supply unit) for supplying (that is, paper supply) the recording paper 5 to the image forming unit 7 for forming a print image is provided at the lower end. 8) is also provided.

  The image forming unit 7 stores, for example, four colors of toner as developers of four colors of yellow (Y), magenta (M), cyan (C), and black (K) so as not to overlap each other. The first to fourth toner cartridges 10 to 13 are included.

  The image forming unit 7 forms toner images as developer images using the toners supplied from the corresponding first to fourth toner cartridges 10 to 13. The four first to fourth image forming units 14 to 14 form toner images as developer images. 17 is also included.

  Further, the image forming unit 7 includes a transfer unit 18 that transfers the toner images formed by the first to fourth image forming units 14 to 17 to the surface of the recording paper 5, and four color toner images on the surface of the recording paper 5. It also has a fixing unit 19 for fixing the toner.

  The first to fourth toner cartridges 10 to 13 are each formed, for example, in a substantially box shape having a relatively long predetermined length. The first to fourth toner cartridges 10 to 13 are in a posture in which the longitudinal direction of the first to fourth toner cartridges 10 to 13 is parallel to the left-right direction of the printer with the door opened with respect to the printer housing 2. It is detachable so that it can be inserted from the left side and pulled out to the left side.

  As a result, when the first to fourth toner cartridges 10 to 13 are loaded in the printer casing 2, for example, black (K) is formed at a predetermined equal interval from the front side to the rear side at the upper end portion of the printer casing 2. ), Cyan (C), magenta (M), and yellow (Y).

  The first to fourth image forming units 14 to 17 are each formed, for example, in a substantially box shape having a relatively long predetermined length. The first to fourth image forming units 14 to 17 are arranged in the longitudinal direction of the first to fourth image forming units 14 to 17 (hereinafter referred to as the unit longitudinal direction) with the door open to the printer housing 2. (Also referred to as a direction) is detachably provided so as to be inserted from the left side in a posture parallel to the horizontal direction of the printer and pulled out to the left side.

  As a result, when the first to fourth image forming units 14 to 17 are loaded in the printer housing 2, the first to fourth image forming units 14 to 17 are arranged at predetermined equal intervals from the front side to the rear side under the first to fourth toner cartridges 10 to 13. They are arranged in order.

  Incidentally, in the printer housing 2, between the first to fourth toner cartridges 10 to 13 and the first to fourth image forming units 14 to 17, a substantially square cylindrical first to fourth toner supply path is provided. 20 to 23 are arranged in order from the front side to the rear side.

  Therefore, when the first to fourth image forming units 14 to 17 are loaded in the printer housing 2, the corresponding first to fourth toner cartridges 10 to 10 via the first to fourth toner supply paths 20 to 23. 13 is connected.

  Here, the first to fourth image forming units 14 to 17 will be described in detail later, but each of them is a photosensitive drum 25 as an image carrier that carries a developer (toner) as a developer image (toner image). To 28 are supported so as to be rotatable in one rotation direction indicated by an arrow d1 in the drawing around a drum rotation shaft as an image bearing member rotation shaft parallel to the unit longitudinal direction (that is, the printer left-right direction). The first to fourth image forming units 14 to 17 include, in place of the photosensitive drums 25 to 28, one drive roller, one or a plurality of driven rollers, and these drive rollers as an image carrier. An endless photosensitive belt stretched around the driven roller may be provided.

  The first to fourth image forming units 14 to 17 use the toner supplied from the corresponding first to fourth toner cartridges 10 to 13 via the first to fourth toner supply paths 20 to 23, respectively. A toner image is formed on the surfaces of the drums 25 to 28 (that is, the surface of the drum main body as the image carrying main body).

  The transfer unit 18 is disposed below the first to fourth image forming units 14 to 17 in the printer housing 2. Under the fourth image forming unit 17, a driving roller 30 for driving the belt is provided on the left and right sides of the printer. Centering on a roller rotation axis parallel to the direction, the rotation is provided in the other rotation direction opposite to the one rotation direction.

  In addition, the transfer unit 18 is provided with a tension roller 31 below the first image forming unit 14 so as to be able to rotate in other rotational directions around a roller rotational axis parallel to the left-right direction of the printer.

  Further, the transfer unit 18 is provided at a predetermined position below the drive roller 30 and the tension roller 31, and a counter roller 32 is provided so as to be able to rotate in other rotation directions around a roller rotation axis parallel to the printer left-right direction. Yes.

  The transfer unit 18 is stretched across the drive roller 30, the tension roller 31, and the opposing roller 32 so that an endless transfer belt 33 forms an inverted triangle.

  The transfer unit 18 is provided with four primary transfer rollers 34 to 37 inside the transfer belt 33 so as to be able to rotate in other rotation directions around a roller rotation axis parallel to the horizontal direction of the printer. The upper portions of the surfaces of the four primary transfer rollers 34 to 37 are pressed against the lower portions of the surfaces of the corresponding photosensitive drums 25 to 28 via the transfer belt 33.

  Further, the transfer unit 18 is provided with a secondary transfer roller 38 below the counter roller 32 so as to be rotatable in one rotation direction about a roller rotation axis parallel to the horizontal direction of the printer, and on the surface of the secondary transfer roller 38. The upper part is pressed against the lower part of the surface of the counter roller 32 via the transfer belt 33.

  The fixing unit 19 is disposed on the rear side of the secondary transfer roller 38 and the counter roller 32 of the transfer unit 18. For example, a heating roller 40 provided with a heater therein has a roller rotation shaft that is parallel to the horizontal direction of the printer. Is provided so as to be rotatable in other rotational directions.

  The fixing unit 19 is provided with a pressure roller 41 that can rotate in one rotation direction around a roller rotation axis parallel to the left-right direction of the printer, and the upper portion of the surface of the pressure roller 41 is disposed on the heating roller 40. It is pressed against the lower part of the surface with a predetermined pressing force.

  On the other hand, the paper feed unit 8 is provided with a paper feed tray 43 in which a plurality of recording papers 5 are stacked in a state where the longitudinal directions of the recording papers 5 are stacked in parallel with the longitudinal direction of the printer.

  Further, the paper feed unit 8 is provided with a feed roller 44 for feeding the recording paper 5 from the paper feed tray 43 one by one so as to be rotatable in one rotation direction about a roller rotation axis parallel to the left-right direction of the printer. Yes.

  In addition to this, in the printer casing 2, the recording paper 5 is placed in the image forming unit 7 from near the front upper side of the paper feed tray 43 to the front of the secondary transfer roller 38 and the counter roller 32 of the transfer unit 18. A conveyance unit (hereinafter also referred to as a sheet feeding conveyance unit) 45 that conveys the sheet to the sheet feeding is disposed.

  The sheet feeding conveyance unit 45 conveys the recording sheet 5 fed from the sheet feeding tray 43 to the image forming unit 7 by various conveyance path forming components such as a plurality of conveyance rollers, a plurality of conveyance guides, and a conveyance motor. A conveyance path (hereinafter also referred to as a sheet feeding conveyance path) is formed.

  Further, in the printer housing 2, a transport unit that transports the recording paper 5 on which the print image is formed on the surface for discharging from the recording paper discharge port from the vicinity of the fixing unit 19 to the vicinity of the recording paper discharge port. (Hereinafter, this is also referred to as a discharge transport unit) 46 is arranged.

  The discharge conveyance unit 46 is a conveyance path for conveying the recording paper 5 fed from the fixing unit 19 to the recording paper discharge port by various conveyance path forming components such as a plurality of conveyance rollers, a plurality of conveyance guides, and a conveyance motor. (Hereinafter, this is also referred to as a discharge conveying path).

  By the way, a control unit (not shown) such as a microcomputer for overall control of the entire color printer 1 is provided in the printer housing 2. The color printer 1 is wirelessly or wiredly connected to a host device (not shown) such as a personal computer that instructs the color printer 1 to print a color image to be printed.

  Accordingly, the control unit is provided with image data representing a color image to be printed from the host device, and when the printing of the color image is instructed, the control unit forms a print image on the surface of the recording paper 5 (that is, prints). Execute the forming process.

  When the print image forming process is executed, the control unit performs the first through fourth predetermined motors for driving the first through fourth image forming units 14 through 17 (hereinafter also referred to as unit drive motors). In the fourth image forming units 14 to 17, the photosensitive drums 25 to 28 and various rollers to be described later are rotated in one rotation direction or the other rotation direction for toner image formation.

  In addition, the control unit applies a predetermined voltage for toner image formation to various rollers of the first to fourth image forming units 14 to 17 from a predetermined voltage source.

  In addition, the control unit rotates the driving roller 30 in the transfer unit 18 via a predetermined motor for driving the transfer unit 18, and in conjunction with the rotation, the transfer belt 33 together with the tension roller 31 and the counter roller 32. Rotate in the other direction of rotation.

  In addition to this, the control unit applies a predetermined voltage for toner image transfer from the predetermined voltage source to the primary transfer rollers 34 to 37 and the secondary transfer roller 38 of the transfer unit 18.

  Further, the control unit heats the heating roller 40 by causing the heater of the fixing unit 19 to generate heat via a predetermined heater power source. In addition, the control unit rotates the heating roller 40 and the pressure roller 41 in the other rotation direction and the one rotation direction opposite to each other in the fixing unit 19 via a predetermined motor for driving the fixing unit 19.

  In this state, the control unit operates the conveyance motor to drive the sheet feeding conveyance unit 45 and the discharge conveyance unit 46, and then rotates the feeding roller 44 in one rotation direction via a predetermined motor. The feeding roller 44 feeds one sheet of recording paper 5 from the paper feeding tray 43 to the image forming unit 7 through the feeding paper feeding conveyance path.

  At this time, the control unit controls the first to fourth image forming units 14 to 17 based on the image data given from the host device to form toner images on the surfaces of the photosensitive drums 25 to 28, respectively. The image is transferred so as to overlap the surface of the transfer belt 33 in order.

  When the control unit conveys the recording paper 5 to the secondary transfer roller 38 through the paper feeding conveyance path, the control unit continues to convey the recording paper 5 between the transfer belt 33 and the secondary transfer roller 38. Then, the toner image on the surface of the transfer belt 33 (that is, toner images of four colors) is transferred to the surface of the recording paper 5 and delivered to the fixing unit 19.

  The control unit heats and presses the recording sheet 5 while conveying the recording sheet 5 so as to be sandwiched between the heating roller 40 and the pressure roller 41 in the fixing unit 19, so that the four color toner images are formed on the surface of the recording sheet 5. After being melted and fixed, a color print image is formed, and then discharged to the recording paper delivery unit 2BX so as to be conveyed to the recording paper discharge port via the discharge conveyance path.

  In this way, the control unit can deliver the recording paper 5 having a color print image formed on the surface thereof to the user via the recording paper delivery unit 2BX.

(1-2) Configuration of Image Forming Unit Next, the configuration of the first to fourth image forming units 14 to 17 will be specifically described. However, the first to fourth image forming units 14 to 17 are configured in the same manner except that different monochrome toners are used to form toner images.

  Therefore, hereinafter, for example, the configuration of the first image forming unit 14 among the first to fourth image forming units 14 to 17 will be described, and the configurations of the other second to fourth image forming units 15 to 17 will be described. Description is omitted.

  As shown in FIGS. 2 and 3, the first image forming unit 14 is provided with a drum unit 50 as an image carrier unit having the above-described photosensitive drum 25.

  The first image forming unit 14 is for forming a developer image (toner image) on the surface of the photosensitive drum 25 (that is, for developing an electrostatic latent image formed on the surface of the photosensitive drum 25 as will be described later). Further, a developing unit 52 as a developer carrying unit having a developing roller 51 as a developer carrying body for carrying developer (toner) is also provided. Instead of the developing roller 51, the developing unit 52 may be provided with a plurality of rollers as a developer carrier and an endless developing belt stretched around the plurality of rollers.

  The drum unit 50 has a front end portion of a left side frame 54 as an image carrier support portion joined to a left end of a drum storage frame 53 as an image carrier storage portion that is long in the left-right direction of the printer, and a right end of the drum storage frame 53. The front end portion of the right side frame 55 as the image carrier support portion is joined to form an approximately U-shaped appearance.

  Further, the developing unit 52 has a left side frame 57 as a developer carrier supporting part joined to the left end of a roller accommodating frame 56 as a developer carrier accommodating part that is long in the left-right direction of the printer. A right side frame 58 as a developer carrier support part is joined to the right end to form a substantially box-like appearance.

  In the first image forming unit 14, the developing unit 52 is mounted between the rear end portion of the left side frame 54 and the rear end portion of the right side frame 55 of the drum unit 50.

  As shown in FIG. 4, the drum unit 50 has an opening that is long in the left-right direction of the printer from a predetermined position on the rear surface of the drum storage frame 53 to a predetermined position on the lower surface.

  In the drum unit 50, a concave portion that is long in the left-right direction of the printer is formed at the rear end portion of the upper surface of the drum storage frame 53, and a long slit is formed in the left-right direction of the printer at the bottom of the concave portion.

  On the other hand, the developing unit 52 has an opening that is long in the left-right direction of the printer at a predetermined position on the front surface of the roller storage frame 56. Further, the developing unit 52 is formed with an intake port (not shown) for taking in toner supplied from the first toner cartridge 10 via the first toner supply path 20 at a predetermined position on the upper surface. .

  In addition to the photosensitive drum 25, the drum unit 50 includes a charging roller 60 as a charging unit that charges the surface of the photosensitive drum 25 for forming an electrostatic latent image that is a basis of the toner image, and the photosensitive drum 25. A cleaning blade 61 is provided as a residual developer removing unit that removes toner remaining after the transfer of the toner image onto the transfer belt 33 from the surface. The drum unit 50 may use a plurality of rollers as charging units and an endless charging belt stretched around the plurality of rollers instead of the charging roller 60. The drum unit 50 may be provided with a cleaning roller as a residual developer removing unit instead of the cleaning blade 61.

  Actually, the photosensitive drum 25 has a drum main body portion having a predetermined length and a predetermined outer diameter such that the drum rotation shaft projects the shaft left end portion and the shaft right end portion from the main body left end surface and the main body right end surface of the drum main body portion. It is provided as such.

  The photosensitive drum 25 has a drum housing frame 53 in which the drum rotation axis is parallel to the left-right direction of the printer and most of the drum body is housed. In a state of protruding downward, the left side frame 54 and the right side frame 55 are supported so as to be rotatable in one rotation direction via the drum rotation shaft.

  The charging roller 60 includes, for example, a roller main body formed of a semiconductive elastic material so as to have a predetermined length and a predetermined outer diameter. Is protruded from the main body left end surface and the main body right end surface of the roller main body portion.

  The charging roller 60 is housed in the drum housing frame 53 with the roller rotation axis parallel to the left-right direction of the printer, and the roller body portion is housed in the rear oblique lower portion of the surface of the roller body. In a state of being pressed against the portion, the left side frame 54 and the right side frame 55 are supported so as to be rotatable in the other rotation direction via the roller rotation shaft. Accordingly, when the photosensitive drum 25 rotates in one rotation direction, the charging roller 60 can rotate in the other rotation direction in conjunction with the rotation.

  The cleaning blade 61 is formed in a substantially strip shape having a predetermined length by an elastic body such as urethane rubber, epoxy rubber, or acrylic rubber.

  The cleaning blade 61 is stored in the drum storage frame 53 in parallel with the left-right direction of the printer, and one edge is directed obliquely downward on the rear side, and the other edge is a predetermined position on the front inner wall of the drum storage frame 53. It is fixed to the blade support part 62 provided in.

  Accordingly, the cleaning blade 61 presses one edge portion against the front portion of the surface of the photosensitive drum 25. Accordingly, when the toner image is transferred from the surface of the photosensitive drum 25 to the transfer belt 33, the cleaning blade 61 is not transferred to the transfer belt 33 from the front side portion after the toner image is transferred to the transfer belt 33 on the surface. The toner remaining on the toner can be removed.

  The drum unit 50 is dropped into the lower end portion of the front inner wall that is obliquely lower front of the cleaning blade 61 in the drum storage frame 53 when the cleaning blade 61 removes toner from the surface of the photosensitive drum 25. A groove-like residual toner conveyance path 53A that is long in the printer left-right direction is provided.

  Incidentally, the drum unit 50 is configured such that the toner transport body 63 formed with the rotation shafts provided at the left end and the right end of the spiral transport main body portion is placed on the left side in a state where the transport main body portion is stored in the residual toner transport path 53A. The frame 54 and the right side frame 55 are supported so as to be rotatable in the other rotation direction via the rotation shafts on one end side and the other end side.

  In the toner transport body 63, a gear (not shown) fixed to the left end of the transport main body is engaged with a gear fixed to the left end of the drum main body of the photosensitive drum 25. By rotating in the other rotation direction according to the rotation in the rotation direction, the toner can be transported in the residual toner transport path 53A and discharged to the outside of the first image forming unit 14.

  On the other hand, in addition to the developing roller 51, the developing unit 52 includes a first supply roller 65 and a second supply roller 66 as developer supply members that carry a developer (toner) for supply to the surface of the developing roller 51. And a toner blade 67 as a developer thickness regulating portion for regulating the thickness of the toner carried on the surface of the developing roller 51 (that is, the surface of the roller body as the developer carrying main body). . In the present embodiment, the developing unit 52 is provided with the two first supply rollers 65 and the second supply roller 66 as developer supply bodies. However, one supply roller may be provided. At least one or more may be provided.

  The developing roller 51 is formed so as to have a predetermined length and a predetermined outer diameter by, for example, a semiconductive urethane rubber in which a conductive material such as carbon is added to a urethane rubber material and an electric resistance is appropriately adjusted. A roller rotation shaft made of conductive metal is provided on the roller body so that the left end and the right end of the shaft protrude from the left end surface and the right end surface of the roller main body.

  The developing roller 51 has a roller housing frame 56 in which the roller rotation shaft is parallel to the left-right direction of the printer, and most of the roller body is housed. However, the front part of the surface of the roller body projects from the opening. In a state where it is pressed against the rear portion of the surface of the photosensitive drum 25, it is supported by the left side frame 57 and the right side frame 58 so as to be rotatable in the other rotation direction via the roller rotation shaft.

  The first supply roller 65 is formed by rotating a conductive metal roller on a roller body portion as a developer supply body portion formed to have a predetermined length and a predetermined outer diameter by, for example, a semiconductive foamed silicon sponge. The shaft left end portion and the shaft right end portion of the shaft are provided so as to protrude from the main body left end surface and the main body right end surface of the roller main body portion.

  The first supply roller 65 has a roller main body stored in the roller storage frame 56 with the roller rotation axis parallel to the left-right direction of the printer, and the front portion of the surface of the roller main body is set to the rear portion of the surface of the developing roller 51. In the pressed state, it is supported by the left side frame 57 and the right side frame 58 so as to be rotatable in the other rotation direction via the roller rotation shaft.

  The second supply roller 66 is formed in the same manner as the first supply roller 65, for example. The second supply roller 66 has a roller main body stored in the roller storage frame 56 with the roller rotation axis parallel to the left-right direction of the printer, and a front diagonal upper portion of the surface of the roller main body is inclined rearward of the surface of the developing roller 51. While being pressed against the lower portion, the left side frame 57 and the right side frame 58 are supported so as to be rotatable in the other rotation direction via the roller rotation shaft.

  The toner blade 67 is formed in a substantially strip shape having a predetermined length using a metal such as stainless steel or phosphor bronze, or a rubber material such as silicone rubber.

  The toner blade 67 is housed in the roller housing frame 56 in parallel with the left-right direction of the printer, and the other edge portion is directed to a predetermined position on the front inner wall of the roller housing frame 56 in a state where one edge portion is inclined rearward and downward. Is fixed to a blade support 68 provided in Accordingly, the toner blade 67 presses one edge portion against the upper portion of the surface of the developing roller 51.

  Therefore, when the toner is transferred from the surface of the developing roller 51 to the electrostatic latent image on the surface of the photosensitive drum 25, the toner blade 67 sets the toner on the surface of the developing roller 51 to a predetermined thickness, and then It can be transferred to a latent image.

  Incidentally, the first image forming unit 14 has an exposure head 69 as an exposure unit for exposing a charged portion on the surface of the photosensitive drum 25 to form an electrostatic latent image.

  The exposure head 69 has a head case that is long in the left-right direction of the printer. A plurality of LED (Light Emitting Diode) elements are arranged in the head case, and the lens array faces the light emitting surface of the plurality of LED elements. And the outer surface is exposed.

  However, the exposure head 69 is disposed in the printer casing 2, and when the first image forming unit 14 is loaded in the printer casing 2, the outer surface of the lens array faces the slit of the drum storage frame 53. I am letting.

  As a result, the exposure head 69 exposes the charged portion of the surface of the photosensitive drum 25 through the slits of the drum housing frame 53 with the irradiation light output from the light emitting surfaces of the plurality of LED elements, and the electrostatic latent image on the surface. Can be formed.

  In addition to this, as shown in FIG. 5, the developing unit 52 has a substantially cylindrical coupling (hereinafter referred to as “this”) for obtaining a driving force from the above-described unit driving motor (not shown) in the printer housing 2. 70 (also referred to as developing unit coupling).

  The developing unit coupling 70 has a substantially triangular engaging recess 70A formed at the tip surface, and a drive transmission gear 70B and a coupling rotating shaft (not shown) are provided at the base portion in this order.

  The developing unit coupling 70 is supported, for example, at a predetermined position in the right side frame 58 so as to be rotatable in one rotation direction via a coupling rotating shaft parallel to the left-right direction of the printer. It protrudes from the inside of the frame 58 to the right side.

  Further, the developing roller 51 has a shaft right end portion of the roller rotation shaft 51A inserted into the right side frame 58, and a drive gear 71 is fixed to the shaft right end portion. The developing roller 51 meshes the drive gear 71 with the drive transmission gear 70B.

  Further, the first supply roller 65 also has a shaft right end portion of the roller rotation shaft 65A inserted into the right side frame 58, and a drive gear 72 is fixed to the right end portion of the shaft. The first supply roller 65 meshes the drive gear 72 with the drive transmission gear 70B.

  Furthermore, the second supply roller 66 also has a shaft right end portion of the roller rotation shaft 66A inserted into the right side frame 58, and a drive gear 73 is fixed to the right end portion of the shaft.

  In the developing unit 52, one intermediate gear 74 is rotatably provided at a predetermined position in the right side frame 58, and the drive gear 72 of the first supply roller 65 and the second supply roller 66 is interposed via the intermediate gear 74. 73 are connected.

  Thus, when the developing unit coupling 70 rotates in one rotation direction, the developing unit 52 rotates the developing roller 51, the first supply roller 65, and the second supply roller 66 in the other rotation direction in conjunction with the rotation. be able to.

  As shown in FIG. 6, the photosensitive drum 25 has a substantially cylindrical cup for obtaining a driving force from the above-described unit driving motor (not shown) in the printer housing 2 at the right end of the drum rotation shaft. A ring (hereinafter also referred to as a drum unit coupling) 77 is provided.

  The drum unit coupling 77 will be described later in detail, but the drum unit coupling 77 has, for example, a plurality of concave portions (for example, substantially fan-shaped) on the surface of the engaging portion 77A that is a tip portion protruding rightward from the right side frame 55 at the right end of the coupling. Three) engaging groove portions 77AX are formed at equiangular intervals.

  That is, in the drum unit coupling 77, the tip end portion of the right end of the coupling has a plurality of substantially fan-shaped (for example, 3) between the plurality of engagement groove portions 77AX and the engagement groove portions 77AX around the center engagement hole portion 77AZ. Are formed as an engaging portion 77A provided with an engaging protrusion 77AY.

  Further, the drum unit 50 is attached so that an opening is formed at the front end portion of the side surface of the right side frame 55 and a cover 78 having a cylindrical coupling insertion portion 78A protruding on one surface closes the opening. It has been.

  Therefore, the drum unit 50 inserts the coupling right end portion of the drum unit coupling 77 into the coupling insertion portion 78A of the cover 78 to protect it from the outside, and the engaging portion 77A through the hole of the coupling insertion portion 78A. It is exposed.

  In the drum unit 50, a coupling insertion hole 55 </ b> A is formed at a front end portion of the side surface of the right side frame 55 at a position facing the developing unit coupling 70.

  The drum unit 50 exposes the leading end portion of the developing unit coupling 70 by inserting the developing unit coupling 70 into the coupling insertion hole 55A.

  On the other hand, as shown in FIG. 7, a drive unit 80 for driving the first image forming unit 14 is disposed in the printer casing 2 on the back side of the loading position of the first image forming unit 14. Yes.

  The drive unit 80 has a substantially flat rectangular casing (hereinafter also referred to as a unit casing) 81, and a plurality of connecting gears (connected to the output shaft of the unit driving motor) in the unit casing 81. (Not shown) is provided.

  The drive unit 80 supports a substantially cylindrical drum unit drive unit 82, to which a drive gear (not shown) is fixed, in the unit casing 81 so as to be rotatable in one rotation direction. It is meshed with one connecting gear.

  In the drum unit driving portion 82, an engaging shaft 82B corresponding to the engaging hole portion 77AZ of the drum unit coupling 77 projects from the center portion of the engaging surface 82A.

  The drum unit driving portion 82 has a substantially fan-column-like engaging claw portion 82 </ b> C corresponding to the plurality of engaging groove portions 77 </ b> AX of the drum unit coupling 77 protruding from the edge portion of the engaging surface 82 </ b> A.

  The drive unit 80 exposes the engagement surface 82A of the drum unit drive unit 82 in the unit housing 81 through a corresponding hole 81AX formed in the left side surface 81A.

  Further, the drive unit 80 supports a substantially stepped cylindrical developing unit drive unit 83, to which a drive gear (not shown) is fixed, in the unit casing 81 so as to be rotatable in the other rotation direction. It is meshed with one connecting gear.

  In the developing unit driving portion 83, a triangular prism-shaped engaging convex portion 83B corresponding to the engaging concave portion 70A of the developing unit coupling 70 protrudes from the central portion of the front end surface 83A.

  The drive unit 80 protrudes the tip end portion of the developing unit drive portion 83 to the left side through a corresponding hole portion 81AY formed in the left side surface 81A.

  With this configuration, when the unit drive motor operates, the drive unit 80 rotates the drum unit drive unit 82 in one rotation direction in accordance with the operation (that is, rotation of the output shaft), and the development unit drive unit 83 also It can be rotated in one rotation direction.

  As shown in FIG. 8, when the first image forming unit 14 is loaded in the printer housing 2, the drive unit 80 presses the side surface of the right side frame 55 of the drum unit 50 against the left side surface 81 </ b> A or closes it. Let

  Here, in the cover 78 described above, the coupling insertion portion 78A has a predetermined thickness, and a tapered portion that is tapered is provided at a tip portion thereof. For this reason, when the first image forming unit 14 is loaded in the printer housing 2, the cover 78 guides the insertion of the coupling insertion portion 78 </ b> A into the hole 81 </ b> AX of the drive unit 80 by the taper portion. The drum unit coupling 77 is inserted into the unit housing 81 together with the coupling insertion portion 78A through the hole 81AX.

  As shown in FIG. 9, when the drum unit coupling 77 is inserted into the unit housing 81, the drive unit 80 drives the drum unit into the engagement hole 77 </ b> AZ and the plurality of engagement grooves 77 </ b> AX of the drum unit coupling 77. The drum unit driving portion 82 can be connected to the drum unit coupling 77 by engaging the engaging shaft 82B and the plurality of engaging claws 82C of the portion 82 so as to be inserted.

  Therefore, in addition to the protection function of the drum unit coupling 77 described above, the coupling insertion portion 78A of the cover 78 has a drum portion coupling 77 and a drum unit by the taper portion when the first image forming unit 14 is loaded into the printer housing 2. It also functions as a connection guide with the drive unit 82.

  At this time, the driving unit 80 engages the engaging concave portion 70A of the developing unit coupling 70 so as to insert the engaging convex portion 83B of the developing unit driving portion 83 so that the developing unit driving portion 83 is engaged with the developing unit cup. It can be connected to the ring 70.

  As a result, when the unit drive motor operates, the drive unit 80 can rotate the drum unit coupling 77 in one rotation direction by the drum unit driving unit 82 in response to the operation.

  Accordingly, at this time, the drive unit 80 can rotate the photosensitive drum 25 in one rotation direction together with the drum unit coupling 77 in the first image forming unit 14.

  The drive unit 80 can rotate the charging roller 60 pressed against the photosensitive drum 25 in the other rotation direction in conjunction with the rotation of the photosensitive drum 25 in the first image forming unit 14.

  Further, the drive unit 80 can rotate the developing roller 51 in the other rotation direction while being pressed against the photosensitive drum 25 in conjunction with the rotation of the developing unit coupling 70 in the first image forming unit 14.

  Further, the drive unit 80 rotates in the other rotation direction while pressing the first supply roller 65 and the second supply roller 66 against the development roller 51 in conjunction with the rotation of the development unit coupling 70 in the first image forming unit 14. Can be made.

  By the way, when the first image forming unit 14 is loaded in the printer housing 2, the roller rotation shaft of the charging roller 60, the roller rotation shaft 51 </ b> A of the developing roller 51, the roller rotation shaft 65 </ b> A of the first supply roller 65, 2 The roller rotation shaft 66A of the supply roller 66 is electrically connected to the corresponding charging roller voltage source, developing roller voltage source, and supply roller voltage source in the printer housing 2 via the drive unit 80, respectively.

  Thus, the first image forming unit 14 can form an electrostatic latent image on the surface of the photosensitive drum 25 via the charging roller 60 in response to application of a predetermined voltage to the charging roller 60 by the charging roller voltage source. Can be charged to a state.

  The first image forming unit 14 can carry toner on the surface of the developing roller 51 in accordance with application of a predetermined voltage to the developing roller 51 by the developing roller voltage source, and the toner can be applied to the surface of the photosensitive drum 25. Can be transferred (attached) to the electrostatic latent image for development (that is, toner can be transferred to the electrostatic latent image on the surface of the photosensitive drum 25).

  Further, the first image forming unit 14 responds to the application of a predetermined voltage to the first supply roller 65 and the second supply roller 66 by the supply roller voltage source, and the surface of the first supply roller 65 and the second supply roller 66. The toner can be carried on the toner, and the toner can be supplied to the surface of the developing roller 51.

  In addition, in the first image forming unit 14, for example, a gear ratio between the drive transmission gear 70 </ b> B and the drive gear 71 of the developing roller 51 is appropriately selected, and the developing roller 51 is made to be faster than the rotational speed of the photosensitive drum 25. It is made to rotate at a high predetermined rotational speed.

  As a result, the first image forming unit 14 causes the surface of the developing roller 51 to slide with respect to the surface of the photosensitive drum 25 when the developing roller 51 rotates together with the photosensitive drum 25 in the other rotation direction and one rotation direction opposite to each other. An appropriate amount of toner for developing the electrostatic latent image can be transferred (attached) from the surface of the developing roller 51 to the surface of the photosensitive drum 25.

  In the first image forming unit 14, for example, the gear ratio between the drive transmission gear 70 </ b> B and the drive gears 72 and 73 of the first supply roller 65 and the second supply roller 66 is appropriately selected. The second supply roller 66 is rotated at a predetermined rotational speed that is lower than the rotational speed of the developing roller 51.

  Accordingly, when the first supply roller 65 and the second supply roller 66 are rotated in the same other rotation direction together with the developing roller 51, the first image forming unit 14 has the first supply roller 65 and the second supply roller 65 with respect to the surface of the developing roller 51. 2 The surface of the supply roller 66 is slid so that the toner can be accurately supplied from the surfaces of the first supply roller 65 and the second supply roller 66 to the surface of the developing roller 51.

  With this configuration, the first image forming unit 14 can form a toner image on the surface of the photosensitive drum 25 and transfer it to the surface of the transfer belt 33 as described above.

  In other words, the control unit operates the unit drive motor during the formation of the print image to rotate the photosensitive drum 25 in one rotation direction in the first image forming unit 14 and the charging roller 60 in conjunction with the rotation. Then, while rotating a part of the surface against a part of the surface of the photosensitive drum 25, the photosensitive drum 25 is rotated in the other rotation direction.

  Further, the control unit rotates the developing roller 51 in the first image forming unit 14 in the other rotation direction while pressing a part of the surface of the developing roller 51 against a part of the surface of the photosensitive drum 25, and the first supply roller 65 and the first roller. (2) The supply roller 66 is rotated in the other rotation direction while a part of the surface is pressed against a part of the surface of the developing roller 51.

  Further, the control unit uses a charging roller voltage source, a developing roller voltage source, and a supply roller voltage source, so that the roller rotation shaft of the charging roller 60, the roller rotation shaft 51A of the development roller 51, the roller rotation shaft 65A of the first supply roller 65, (2) A voltage having a voltage value corresponding to the roller rotation shaft 66A of the supply roller 66 is applied.

  Accordingly, the control unit charges the surface of the photosensitive drum 25 by the charging roller 60 and supplies toner to the surface of the developing roller 51 by the first supply roller 65 and the second supply roller 66.

  In this state, the control unit controls the exposure head 69 of the first image forming unit 14 based on the corresponding color data included in the image data of the color image to be printed, and sends the exposure head 69 with the color data. The corresponding irradiation light is output.

  As a result, the control unit forms an electrostatic latent image on the exposed portion of the first image forming unit 14 by irradiating the charged portion on the surface of the photosensitive drum 25 with irradiation light.

  Further, the control unit transfers (attaches) toner from the surface of the developing roller 51 to the electrostatic latent image on the surface of the photosensitive drum 25 in the first image forming unit 14 (that is, develops the electrostatic latent image with toner). Thus, a toner image is formed on the surface of the photosensitive drum 25.

  In this way, the control unit forms a toner image on the surface while rotating the photosensitive drum 25 in one rotation direction in the first image forming unit 14, and transfers the formed toner image from the surface to the surface of the transfer belt 33. can do.

  As shown in FIG. 10, in the drum unit coupling 77, as described above, the engagement shaft 82B of the drum unit drive unit 82 is inserted into the engagement hole 77AZ, and the drum unit drive unit is inserted into each of the plurality of engagement grooves 77AX. 82 engaging claws 82C are inserted.

  Accordingly, the drum unit coupling 77 generates a driving force (hereinafter also referred to as a drum driving force) applied from the driving unit 80 via the drum unit driving unit 82 for rotating the photosensitive drum 25 according to the operation of the unit driving motor. Can receive.

  However, when the drum unit driving portion 82 is connected to the drum unit coupling 77, the tip end portion of the engagement shaft 82B is formed in a tapered shape in order to realize easy and reliable connection, and the engagement hole portion 77AZ. So that it can be plugged in securely.

  The drum unit driving portion 82 is selected such that the length in one rotation direction of the plurality of engagement claw portions 82C is shorter than the length in one rotation direction of the plurality of engagement groove portions 77AX of the drum unit coupling 77. The engaging claw 82C can be surely inserted into the engaging groove 77AX.

  Therefore, the drum unit coupling 77 has a front surface 82CX of the engaging claw portion 82C on the rear surface 77AYX of the plurality of engaging protrusions 77AY when the drum unit driving portion 82 rotates in one rotation direction according to the operation of the unit driving motor. When it is pressed, it rotates in one rotation direction.

  Incidentally, the rear surface 77AYX of the engagement protrusion 77AY of the drum unit coupling 77 is a rear surface when viewed in one rotation direction, and the front surface 82CX of the engagement claw portion 82C of the drum unit driving unit 82 is in one rotation direction. This is the front side when viewed in.

  Thus, when the drum unit coupling 77 is rotated in one rotation direction by receiving the drum driving force as described above, the photosensitive drum 25 can be rotated in the one rotation direction at a predetermined rotation speed together with the drum unit coupling 77. Incidentally, in the following description, the rotation speed when the photosensitive drum 25 rotates only with the drum driving force is also referred to as a drum specified rotation speed.

  However, as shown in FIG. 11, the photosensitive drum 25 has external forces F1 and F2 for accelerating the drum specified rotational speed and an external force F3 for decelerating in addition to the drum driving force during rotation in one rotation direction. F4 is added.

  Actually, in the first image forming unit 14, during the rotation of the photosensitive drum 25 in one rotation direction as described above, the developing roller 51 is pressed against the photosensitive drum 25 with a predetermined pressing force and is faster than the drum predetermined rotation speed. It is rotating in the other rotation direction at the rotation speed.

  Therefore, the rotational speed of the photosensitive drum 25 is accelerated by pulling from the developing roller 51 in one rotation direction during rotation in one rotation direction (that is, the photosensitive drum 25 is rotated at a rotation speed faster than the drum predetermined rotation speed). The external force F1 is applied.

  In the first image forming unit 14, basically, while the photosensitive drum 25 rotates in one rotation direction, the transfer belt 33 is basically pressed against the photosensitive drum 25 through the primary transfer roller 34 with a predetermined pressing force. The drum is rotated in the other rotation direction at a rotation speed substantially equal to the drum specified rotation speed.

  However, in the first image forming unit 14, for example, if there are variations in the formation accuracy and arrangement accuracy of components such as the photosensitive drum 25, the transfer belt 33, and the driving roller 30 and the tension roller 31 that contribute to the rotation thereof, Due to the variation, the transfer belt 33 may rotate in the other rotational direction at a rotational speed slightly higher than the drum predetermined rotational speed.

  In such a case, the rotational speed of the photosensitive drum 25 is slightly accelerated by pulling the photosensitive drum 25 from the transfer belt 33 in one rotation direction during rotation in one rotation direction (that is, slightly faster than the drum predetermined rotation speed). An external force F2 is applied such as rotating at a rotational speed.

  Further, in the first image forming unit 14, during rotation of the photosensitive drum 25 in one rotation direction, the charging roller 60 is rotated in the other rotation direction in conjunction with the rotation of the photosensitive drum 25 in one rotation direction.

  However, since the charging roller 60 rotating in the other rotation direction is pressed against the photosensitive drum 25 with a predetermined pressing force during rotation in one rotation direction, the rotation speed is slightly reduced from the charging roller 60. An external force F3 is applied such that it is rotated (that is, rotated at a rotational speed slightly slower than the drum-specified rotational speed).

  Furthermore, in the first image forming unit 14, the cleaning blade 61 that is fixedly arranged is pressed against the photosensitive drum 25 with a predetermined pressing force during the rotation of the photosensitive drum 25 in one rotation direction.

  For this reason, the external force F4 is applied to the photosensitive drum 25 so as to slightly reduce the rotation speed from the cleaning blade 61 during rotation in one rotation direction (that is, to rotate at a rotation speed slightly slower than the drum specified rotation speed). It has been added.

  As for the external force applied to the photosensitive drum 25, external forces F1 and F2, which are applied from the developing roller 51 and the transfer belt 33 and accelerate the rotational speed, are applied from the charging roller 60 and the cleaning blade 61, and the rotational speed is reduced. The external forces F3 and F4 are greatly exceeded.

  Therefore, when the entire external forces F1 to F4 applied to the photosensitive drum 25 are viewed (that is, when the external forces F1 to F4 are summed), the rotation speed is accelerated (that is, the rotation is faster than the drum specified rotation speed). External force (hereinafter referred to as acceleration external force) such as rotating at a speed) is applied.

  Therefore, as shown in FIG. 12, the drum unit coupling 77 engages the front surfaces 77AYY of the plurality of engaging protrusions 77AY when an acceleration external force is applied to the photosensitive drum 25 rotating in one rotation direction. The drum unit driving unit 82 is rotated at a rotational speed faster than the drum prescribed rotational speed so as to be pressed against the rear surface 82CY of the joint claw 82C, and is also rotated in one rotation direction at the high rotational speed.

  Incidentally, the front surface 77AYY of the engagement protrusion 77AY of the drum unit coupling 77 is a front surface when viewed in one rotation direction, and the rear surface 82CY of the engagement claw portion 82C of the drum unit drive unit 82 is in one rotation direction. This is the rear surface when viewed.

  Thus, when the acceleration external force is applied in this way, the photosensitive drum 25 rotates in one rotation direction together with the drum unit coupling 77 at a rotation speed faster than the drum predetermined rotation speed.

  For this reason, the first image forming unit 14 is formed so that it can rotate at the drum specified rotation speed even if it receives an acceleration external force while the photosensitive drum 25 rotates in one rotation direction.

  Therefore, the configuration of the photosensitive drum 25 and the configuration of the drum unit 50 for rotating the photosensitive drum 25 at the drum predetermined rotation speed will be specifically described below.

  As shown in FIGS. 13 to 16, the photosensitive drum 25 includes the drum body 85 and the drum rotation shaft 86 as described above. The drum body 85 is formed, for example, by providing a photoconductive layer in which a charge generation layer and a charge transport layer are sequentially laminated on the surface of a conductive substrate such as drum-shaped aluminum having a predetermined outer diameter. An organic photoreceptor 85A is provided.

  The drum body 85 has the above-described gear 85B attached to the left end of the organic photoreceptor 85A, and a shaft insertion hole (hereinafter also referred to as a right shaft insertion hole) at the right end of the organic photoreceptor 85A. A substantially stepped cylindrical shaft locking portion 85C having 85CX is attached and formed.

  The drum body 85 has a shaft insertion hole 85BX (hereinafter also referred to as a left shaft insertion hole) in the center of the gear 85B. Further, the drum main body 85 has a right shaft insertion hole 85C on the right end surface of the shaft locking portion 85C (that is, the right end surface of the main body). It is formed to intersect at 85CX.

  On the other hand, the drum rotation shaft 86 is selected to have a predetermined length that is longer than the length of the drum body 85. The drum rotation shaft 86 is inserted at a predetermined position near the right end of the shaft on the front surface with a first pin passing through the center of the rotation axis perpendicular to the longitudinal direction of the drum rotation shaft 86 (hereinafter also referred to as the axial longitudinal direction). A hole is formed.

  Further, in the drum rotation shaft 86, a shaft positioning pin 87 for positioning the mounting position with respect to the drum main body portion 85 is inserted into the first pin insertion hole portion, and one end portion and the other end portion of the shaft positioning pin 87 are formed on the surface. It protrudes from the facing position.

  The drum body 85 then inserts the shaft positioning pin 87 into the shaft positioning groove 85CY by sequentially inserting the left end of the drum rotation shaft 86 into the right shaft insertion hole 85CX and the left shaft insertion hole 85BX of the drum body 85. Is inserted and locked to the bottom of one of the linear portions, and the mounting position of the drum rotation shaft 86 is positioned.

  As a result, the drum main body 85 projects the left end of the drum rotation shaft 86 from the gear 85B to the left, and the right end of the drum projects from the shaft locking portion 85C to the right. It is provided so that it can rotate integrally.

  In the drum unit 50, a left bearing mounting hole portion 54A and a right bearing mounting hole portion 55B are formed at predetermined positions on the inner surfaces of the left side frame 54 and the right side frame 55.

  Further, in the drum unit 50, a pair of a left bearing portion 88 and a right bearing portion 89 are attached to the left bearing mounting hole portion 54A and the right bearing mounting hole portion 55B of the left side frame 54 and the right side frame 55.

  The photosensitive drum 25 has a shaft left end protruding from the left shaft insertion hole 85BX to the left side of the gear 85B on the drum rotation shaft 86 and is inserted into the left bearing portion 88, and is locked from the right shaft insertion hole 85CX. The right end portion of the shaft protruding to the right side of the portion 85C is inserted into the right bearing portion 89.

  Thus, the photosensitive drum 25 is supported by the left side frame 54 and the right side frame 55 of the drum unit 50 through a pair of left bearing portion 88 and right bearing portion 89 so as to be rotatable in one rotation direction.

  By the way, the drum unit 50 is provided with a coupling arrangement portion 55CX which is a space surrounded by a substantially stepped cylindrical partition plate 55C on the right side of the right bearing portion 89 in the right side frame 55.

  The coupling arrangement portion 55CX is formed as a space where the side surface side of the right side frame 55 is wider (ie, has a larger diameter) than the width (ie, diameter) on the right bearing portion 89 side.

  Incidentally, in the following description, a narrow space portion on the right bearing portion 89 side in the coupling arrangement portion 55CX is also called a narrow arrangement area, and a wide space portion on the side surface side of the right side frame 55 is arranged in a wide arrangement. Also called an area.

  Therefore, in the photosensitive drum 25, the right end portion of the drum rotation shaft 86 is inserted into the coupling arrangement portion 55CX, and the right end portion of the shaft is positioned near the side surface of the right side frame 55.

  Then, the drum rotation shaft 86 is positioned at a predetermined position closer to the right end of the shaft than the position supported by the right bearing portion 89 on the surface (that is, a predetermined position in the wide arrangement area of the coupling arrangement portion 55CX) and the longitudinal direction of the shaft. A second pin insertion hole that passes through the center of the rotation axis at right angles is formed.

  The drum rotation shaft 86 has a coupling positioning pin 90 for positioning the mounting position of the drum unit coupling 77 inserted in the second pin insertion hole, and one end and the other end of the coupling positioning pin 90 are connected to each other. It protrudes from the facing position on the surface.

  For example, the drum unit coupling 77 is made of a predetermined resin material such as a silicone resin having a relatively small friction coefficient, and the coupling left end 77B, the coupling center 77C, and the coupling right end have substantially different outer diameters. It is formed in a cylindrical shape.

  Incidentally, the drum unit coupling 77 has a coupling left end 77B, a coupling right end, and a coupling center so that the outer diameter increases in the order of the coupling left end 77B, the coupling right end, and the coupling center 77C. 77C is selected to have different predetermined outer diameters.

  The drum unit coupling 77 has a plurality of engagement groove portions 77AX and a plurality of engagement projection portions 77AY provided at the tip end portion of the coupling right end portion as described above, and the engagement portion 77A protruding rightward from the right side frame 55. It is formed as.

  The drum unit coupling 77 passes through the coupling center perpendicular to the longitudinal direction of the drum unit coupling 77 (hereinafter also referred to as the coupling longitudinal direction) on the left step surface of the coupling center portion 77C. A coupling positioning groove 77CX for positioning the mounting position with respect to the shaft 86 is formed.

  Further, the drum unit coupling 77 has a pair of substantially V-shaped pin insertion guides 77BX extending from the coupling left end surface to the bottom of the coupling positioning groove 77CX at a position opposed to the surface of the coupling left end 77B. Yes.

  The drum rotation shaft 86 inserts the shaft right end into the shaft insertion hole 77D of the drum unit coupling 77, so that the coupling positioning pin 90 is moved to the bottom of the coupling positioning groove 77CX via the pair of pin insertion guides 77BX. The drum unit coupling 77 is attached to the right end of the shaft by inserting and locking.

  As a result, the drum rotation shaft 86 is inserted into the shaft insertion hole 77D of the drum unit coupling 77 up to the root portion of the coupling right end so that the cup rotation shaft 86 is inserted into the narrow arrangement area of the coupling arrangement portion 55CX. The drum unit coupling 77 is provided so as to be rotatable integrally with the ring left end portion 77B and the coupling central portion 77C and the root portion of the coupling right end portion disposed in the wide arrangement area.

  By the way, the drum unit coupling 77 is provided so as to rotate integrally with the drum rotation shaft 86 of the photosensitive drum 25 as described above. The acceleration external force given above is transmitted through the drum rotation shaft 86. That is, the drum unit coupling 77 indirectly receives the acceleration external force described above when rotated in one rotation direction together with the photosensitive drum 25.

  For this reason, the drum unit coupling 77 applies a load (hereinafter also referred to as a deceleration load) that causes the root portion of the right end of the coupling to decelerate the rotation in one rotation direction to the drum unit coupling 77. The torsion spring 92 is attached to a mounting portion (hereinafter also referred to as a spring mounting portion) 77E, and the surface is formed in a smooth cylindrical shape.

  The drum unit coupling 77 is connected to an annular portion (hereinafter also referred to as a spring annular portion) 92A of the torsion spring 92 from one end portion (hereinafter also referred to as a spring one end portion) 92B side of the torsion spring 92. The right end of the ring is inserted.

  As a result, the drum unit coupling 77 causes the torsion spring 92 to bring the spring end portion 92B close to the right step surface of the coupling central portion 77C (ie, slightly to the spring mounting portion 77E that is the base portion of the coupling right end portion). Attached).

  The torsion spring 92 is made of a predetermined metal wire having a diameter of about 1.0 [mm], for example, so that the spring one end 92B protrudes from the outer surface of the spring annular portion 92A, but the other end is a part of the spring annular portion 92A. (That is, not projecting to the outer surface side of the spring annular portion 92A).

  In the following description, in the spring annular portion 92A of the torsion spring 92, the outer surface is also called the annular portion outer surface, the inner surface is also called the annular portion inner surface, the outer diameter is also called the annular portion outer diameter, and the inner diameter is also called the annular portion inner diameter. Furthermore, when it is not necessary to distinguish between the outer diameter of the annular portion and the inner diameter of the annular portion, or when both are indicated, these are collectively referred to as a spring diameter. In the following description, the diameter of the metal wire forming the torsion spring 92 is also referred to as a spring wire diameter.

  In addition, the torsion spring 92 is selected so that the inner diameter of the annular portion is smaller than the outer diameter of the spring mounting portion 77E so as to apply a deceleration load to the drum unit coupling 77.

  Therefore, the torsion spring 92 is attached to the spring attachment portion 77E so that the spring annular portion 92A is tightened with a predetermined tightening force (ie, the inner surface of the annular portion is pressed against the surface of the spring attachment portion 77E). Yes.

  Further, when the torsion spring 92 is attached to the spring attachment portion 77E of the drum unit coupling 77, the tip end portion of the spring one end portion 92B protrudes outward from the surface of the coupling center portion 77C.

  The right side frame 55 of the drum unit 50 has a notch formed in the upper part of the wide arrangement area of the coupling arrangement part 55CX in the partition plate 55C.

  Thereby, the right side frame 55 protrudes the front-end | tip part of the spring one end part 92B of the torsion spring 92 to the upper side of the wide arrangement | positioning area through the notch part of the partition plate 55C.

  Further, the right side frame 55 is formed with a notch portion in the partition plate 55C, so that the rear edge portion of the notch portion (that is, the rear portion remaining without being notched) is formed on the upper portion of the partition plate 55C. Is provided as a rotation restricting portion 55CY for restricting rotation in one rotation direction.

  Therefore, when the drum unit coupling 77 rotates in one rotation direction, the drum unit 50 restricts the torsion spring 92 from rotating in one rotation direction by causing the tip of the spring one end portion 92B to abut against the rotation restricting portion 55CY. be able to.

  As a result, the drum unit 50 is slid while the inner surface of the annular portion of the torsion spring 92 is in pressure contact with the surface of the spring mounting portion 77E, and the drum unit coupling 77 is applied in one rotation direction with a deceleration load applied by the torsion spring 92. Can be rotated.

  As a result, the drum unit 50 can also rotate the photosensitive drum 25 integrated with the drum unit coupling 77 in one rotation direction with a deceleration load applied by the torsion spring 92.

  By the way, when the drum unit coupling 77 rotates in one rotation direction, the torsion spring 92 is moved to the spring annular portion 92A by the rotation of the drum unit coupling 77 even if rotation in the one rotation direction is restricted by the rotation restriction portion 55CY. A rotational force is applied to pull and rotate in one rotation direction.

  For this reason, as shown in FIG. 19, even if the rotational force in one rotation direction acts in this way, the torsion spring 92 tightens the spring annular portion 92A from the spring one end portion 92B side to the spring mounting portion 77E. In order to prevent the tightening from becoming unnecessarily strong, the spring annular portion 92A is configured so that the spring winding direction of the metal wire from the spring one end 92B side to the other end (that is, the winding direction of the metal wire in the spring annular portion 92A) The coupling 77 is formed so as to coincide with the other rotation direction opposite to the one rotation direction when rotating, and is attached to the spring attachment portion 77E.

  As a result, when a rotational force in one rotation direction acts on the spring annular portion 92A in a state in which the rotation in one rotation direction is restricted, the spring annular portion 92A is moved to the spring one end portion 92B side accordingly. Thus, the spring diameter is widened to prevent the spring mounting portion 77E from being tightened excessively. That is, the torsion spring 92 prevents an excessive deceleration load from being applied to the photosensitive drum 25 together with the drum unit coupling 77 when rotation in one rotation direction is restricted by the rotation restricting portion 55CY. The portion 92A prevents the surface of the spring mounting portion 77E of the drum unit coupling 77 from being worn.

  However, as shown in FIGS. 20 and 21, the cover 78 has a case where the inner diameter of the coupling insertion portion 78A into which the torsion spring 92 is inserted together with the drum unit coupling 77 is not rewound at all. A predetermined inner diameter larger than the outer diameter of the annular portion is selected.

  Further, the cover 78 extends from the left end to the right end of the inner surface 78AX facing the outer surface of the annular portion of the torsion spring 92 in the coupling insertion portion 78A, for example, parallel to the central axis of the coupling insertion portion 78A (that is, both in the coupling longitudinal direction). A plurality of (for example, four) rewinding restricting portions 78AY that are rib-shaped in parallel are projected at equal intervals.

  Further, the cover 78 is selected to have a predetermined outer diameter so that the outer diameter of the coupling insertion portion 78A can be inserted into the wide arrangement area of the coupling arrangement portion 55CX. Therefore, when the cover 78 is attached to the right side frame 55, the rear oblique upper portion of the left end portion on the outer surface of the coupling insertion portion 78A is brought close to the rotation restricting portion 55CY.

  In the cover 78, a concave portion wider than the spring wire diameter is formed as a spring one end accommodating portion 78AZ at a predetermined position near the rotation restricting portion 55CY on the left end surface 78AM of the coupling insertion portion 78A.

  Thus, when the torsion spring 92 is inserted together with the drum unit coupling 77 into the coupling insertion portion 78, the cover 78 stores the root portion of the spring one end portion 92B in a non-contact state with the spring one end storage portion 78AZ. The left end of each of the plurality of rewinding restricting portions 78AY slightly protrudes to the left side of the spring annular portion 92A and the right end slightly protrudes to the right side of the spring annular portion 92A. ing.

  When the spring annular portion 92A is not rewound, the plurality of rewinding restricting portions 78AY are, for example, about 0.5 [mm] narrower than the spring wire diameter from the outer surface of the annular portion. When the spring annular portion 92A is rewound and the spring diameter is widened, the coupling insertion portion is arranged so that the outer surface of the annular portion abuts against the projecting surface to restrict rewinding. The protrusion height from the inner surface 78AX of 78A to the protrusion surface is appropriately selected.

  That is, even if the spring annular portion 92A is rewound from the spring one end portion 92B side, when the spring diameter is increased by a predetermined amount smaller than the spring wire diameter, the plurality of rewinding restricting portions 78AY have the annular portion outer surface on the protruding surface. The projecting height is selected so that the drum unit coupling 77 is applied with a deceleration load that cancels the above-described acceleration external force by causing the abutting and rewinding to suppress the spread of the spring diameter.

  As a result, when the drum unit coupling 77 rotates in one rotation direction according to the operation of the unit drive motor, the drum unit 50 is rewound by restricting the rotation of the torsion spring 92 in one rotation direction by the rotation restricting portion 55CY. Then, the rewinding can be restricted from the outer surface side of the annular part by the plurality of rewinding restriction parts 78AY, and the tightening force can be adjusted together with the amount of expansion of the spring diameter.

  At this time, the drum unit 50 is slid while the annular portion inner surface is pressed against the surface of the spring mounting portion 77E even if the tightening force is adjusted together with the amount of spread of the spring diameter. A deceleration load is applied to the ring 77 to cancel the acceleration external force, and the drum unit coupling 77 can be rotated in one rotation direction by the drum driving force received from the drum unit driving unit 82 as in the case described above with reference to FIG. .

  Therefore, the drum unit 50 can also rotate the photosensitive drum 25 integrated with the drum unit coupling 77 in one rotation direction by applying a deceleration load by the torsion spring 92 to cancel the acceleration external force.

  In this way, the drum unit 50 responds to the drum driving force transmitted from the drum unit driving unit 82 to the drum unit coupling 77 even when the photosensitive drum 25 receives an acceleration external force when the print image is formed. The drum can be stabilized and rotated in one rotation direction at a specified rotation speed.

  Therefore, in the drum unit 50, when the print image is formed, the rotation speed of the photosensitive drum 25 becomes faster than the drum regulation rotation speed, and the toner image formed on the surface contracts in one rotation direction as compared with the original shape. Can be prevented from occurring.

  By the way, in the drum unit coupling 77, the shaft right end of the drum rotation shaft 86 extends to the portion related to the spring mounting portion 77E of the coupling right end with respect to the shaft insertion hole 77D (that is, the shaft right end of the drum rotation shaft 86). The shaft tip portion is inserted so as to be positioned in the spring mounting portion 77E.

  As a result, the drum unit coupling 77 can efficiently transmit the deceleration load applied to the spring mounting portion 77E by the torsion spring 92 to the drum rotation shaft 86 and accurately cancel the acceleration external force applied to the photosensitive drum 25. .

  The drum unit coupling 77 receives the deceleration load applied by the torsion spring 92 in this way at the right end portion of the drum rotation shaft 86 via the spring mounting portion 77E, so that deformation or breakage due to the application of the deceleration load, A change in the mounting posture with respect to the drum rotation shaft 86 and a displacement of the mounting position can also be prevented accurately.

  The drum rotation shaft 86 applies a deceleration load applied to the spring mounting portion 77E of the drum unit coupling 77 by the torsion spring 92 at the shaft tip portion closer to the shaft right end surface than the support position by the right bearing portion 89 at the shaft right end portion. is recieving. Thereby, the drum rotating shaft 86 makes the distance from the support position by the right bearing part 89 to the application position of the deceleration load as long as possible at the right end of the shaft.

  Therefore, even if the right end portion of the drum rotation shaft 86 is eccentric due to bending due to the application of a deceleration load, the right bearing portion 89 can suppress the eccentricity. As a result, the drum rotation shaft 86 can be stably rotated in one rotation direction without decentering the drum body 85 integrated with the drum rotation shaft 86.

(1-3) Operation and Effect of Embodiment In the above configuration, in the color printer 1, the drum unit 50 can be rotated in one rotation direction via the drum rotation shaft 86 in the first to fourth image forming units 14 to 17. A drum unit coupling 77 is provided at the right end of the drum rotating shaft 86 of the photosensitive drum 25 supported by the drum 25, and a torsion spring 92 is tightened to a spring mounting portion 77E of the drum unit coupling 77 with a predetermined tightening force. I tried to install in the state.

  In the color printer 1, when the drum unit coupling 77 rotates in one rotation direction in accordance with the operation of the unit drive motor in the drum unit 50 in the first to fourth image forming units 14 to 17, one rotation direction of the torsion spring 92 occurs. The rotation restricting portion 55CY for restricting the rotation to is provided.

  In the color printer 1, the rotation of the torsion spring 92 in one rotation direction is restricted to the drum unit 50 in the first to fourth image forming units 14 to 17 with the drum unit coupling 77 rotating in one rotation direction. Thus, when the torsion spring 92 is unwound, the unwinding restricting portion 78AY for restricting the unwinding is provided to face the outer surface of the annular portion.

  Therefore, the color printer 1 rotates the photosensitive drum 25 together with the drum unit coupling 77 in one rotation direction in the first to fourth image forming units 14 to 17 in accordance with the operation of the unit drive motor when forming a print image. While the rotation restricting portion 55CY restricts the rotation of the torsion spring 92 in one rotation direction, the unwinding restricting portion 78AY accurately regulates the unwinding of the torsion spring 92 from the outer surface side of the annular portion, thereby increasing the amount of spring diameter. At the same time, the tightening force can be adjusted.

  Therefore, the color printer 1 applies the deceleration load to the drum unit coupling 77 by the torsion spring 92 and cancels the acceleration external force, and the photosensitive drum 25 is used as a drum driving force integrally with the drum unit coupling 77 to which the deceleration load is applied. It is possible to reliably prevent the rotation speed of the photosensitive drum 25 from being changed by changing the deceleration load applied to the drum unit coupling 77 by the torsion spring 92 by rotating the drum drum at a corresponding drum specified rotation speed. .

  According to the above configuration, in the color printer 1, in the drum units 50 of the first to fourth image forming units 14 to 17, the shaft right end portion of the drum rotation shaft 86 of the photosensitive drum 25 supported to be rotatable in one rotation direction. A drum unit coupling 77 is provided, and a torsion spring 92 is attached to the drum unit coupling 77 with a predetermined tightening force, and a rotation restricting portion 55CY for restricting rotation of the torsion spring 92 in one rotation direction is provided. At the same time, the unwinding restricting portion 78AY for restricting unwinding of the torsion spring 92 is provided to face the outer surface of the annular portion.

  As a result, when the color printer 1 forms a print image, the first to fourth image forming units 14 to 17 use the rotation restricting portion 55CY to restrict the rotation of the torsion spring 92 in one rotation direction, while the rewind restricting portion. 78AY can reliably regulate the rewinding of the torsion spring 92 from the outer surface side of the annular portion to adjust the tightening force. As a result, the photosensitive drum 25 can be driven together with the drum unit coupling 77, and the deceleration load can be applied by the torsion spring 92. When the external acceleration force is applied and the acceleration external force is canceled, the drum is rotated in one rotation direction at a drum specified rotational speed corresponding to the drum driving force, and the deceleration load applied to the drum unit coupling 77 by the torsion spring 92 is changed. It is possible to reliably prevent the rotation speed from changing.

  Therefore, the color printer 1 can prevent the toner image formed on the surface of the photosensitive drum 25 from shrinking in one rotation direction and causing a formation defect, and as a result, it can almost certainly prevent the quality of the printed image from deteriorating. can do.

  In the color printer 1, a drum unit coupling 77 is inserted into a cover 78 attached to the right side frame 55 of the drum unit 50, and this is protected from the outside, and a coupling for guiding the connection with the drum unit driving unit 82. An unwinding restricting portion 78AY is provided on the inner surface 78AX of the insertion portion 78A.

  That is, in the color printer 1, the coupling insertion portion 78A of the cover 78 is provided with a rewinding restriction function as well as a protection function and a connection guide function for the drum unit coupling 77.

  Therefore, the color printer 1 can prevent the configuration from becoming complicated by providing the rewind restricting portion 78AY for the drum unit 50 as a dedicated one separately from other components.

  In the color printer 1, the unwinding restricting portion 78 </ b> AY of the inner surface 78 </ b> AX of the coupling insertion portion 78 </ b> A in the cover 78 is a rib parallel to the coupling longitudinal direction when the drum unit coupling 77 is inserted into the coupling insertion portion 78 </ b> A. It was made to form in a shape.

  Accordingly, when the color printer 1 is formed so that the coupling insertion portion 78A regulates the unwinding of the torsion spring 92 by the unwinding restricting portion 78AY and optimally adjusts the tightening force together with the amount of spring diameter spread, for example, The productivity can be improved as compared with the case where the coupling insertion portion 78A is formed so that the entire inner surface 78AX functions as a rewinding restriction portion.

  Further, in the color printer 1, a plurality of rewinding restricting portions 78AY are provided on the inner surface 78AX of the coupling insertion portion 78A, and when the spring annular portion 92A of the torsion spring 92 is not rewound, the protruding surface from the outer surface of the annular portion is used as the spring wire material. When the spring annular portion 92A is unwound and the spring diameter is widened by forming a gap L1 narrower than the diameter, the outer surface of the annular portion is abutted against the projecting surface, and rewinding is restricted. I did it.

  Therefore, when the color printer 1 regulates the rewinding of the torsion spring 92 by the plurality of rewinding restricting portions 78AY while restricting the rotation of the torsion spring 92 in one rotation direction by the rotation restricting portion 55CY, the torsion spring 92 Thus, the deceleration load for canceling the acceleration external force can be accurately generated and applied to the photosensitive drum 25 together with the drum unit coupling 77.

  Further, in the color printer 1, a spring one end storage portion 78AZ is formed on the left end surface 78AM of the coupling insertion portion 78A, and when the torsion spring 92 is inserted into the coupling insertion portion 78 together with the drum unit coupling 77, the spring one end storage portion. 78AZ is housed in the root portion of one end 92B of the spring so that the projecting surface of the rewinding restricting portion 78AY is reliably opposed from the left end to the right end of the outer surface of the annular portion along the central axis of the spring annular portion 92A. I made it.

  Accordingly, when the rotation restricting portion 55CY restricts the rotation of the torsion spring 92 in the one rotation direction, the color printer 1 more reliably rewinds the torsion spring 92 from the outer surface side of the annular portion by the plurality of rewind restricting portions 78AY. Therefore, the tightening force can be adjusted accurately.

  Further, in the color printer 1, the torsion spring 92 is attached to the drum unit coupling 77 so as to be related to the insertion position of the right end portion of the drum rotation shaft 86.

  Therefore, the color printer 1 efficiently transmits the deceleration load applied to the drum unit coupling 77 by the torsion spring 92 to the drum rotation shaft 86, and accurately cancels the acceleration external force applied to the photosensitive drum 25 by the deceleration load. Can do.

  In addition, in the color printer 1, in the drum unit coupling 77, the application of a deceleration load by the torsion spring 92 may cause deformation or breakage, a change in the mounting posture with respect to the drum rotation shaft 86, and a displacement in the mounting position. Can be prevented.

  Further, in the color printer 1, the torsion spring 92 is attached to the drum unit coupling 77 so as to be related to the shaft tip portion closer to the shaft right end surface than the support position by the right bearing portion 89 at the shaft right end portion of the drum rotation shaft 86. did.

  Accordingly, the color printer 1 can increase the distance from the support position by the right bearing portion 89 to the deceleration load application position as much as possible at the right end portion of the drum rotation shaft 86.

  As a result, in the color printer 1, even if the right end portion of the drum rotation shaft 86 is deflected due to the application of a deceleration load or the like, the eccentricity is suppressed by the right bearing portion 89 and the drum rotation shaft 86 is suppressed. The drum main body 85 integrated with can be stably rotated in one rotation direction without being eccentric.

(2) Other embodiments (2-1) Other embodiments 1
In the above-described embodiment, the case where the rotation restricting portion 55CY is provided on the partition plate 55C in the right side frame 55 in the drum unit 50 has been described.

  However, the present invention is not limited to this. For example, the coupling insertion portion 78A of the cover 78 is formed with a notch that is parallel to the central axis (that is, parallel to the longitudinal direction of the coupling), and one of the notches. The edge portion may be provided as a rotation restricting portion.

  In the case of such a configuration, the present invention forms, for example, the torsion spring 92 such that one end thereof is a part of the spring annular portion 92A and the other end protrudes from the outer surface of the spring annular portion 92A.

  In the present invention, the torsion spring 92 is placed on the spring mounting portion 77E of the drum unit coupling 77 so that one end is close to the right step surface of the coupling central portion 77C and the other end is positioned on the engaging portion 77A side. May be attached so as to be engageable with the rotation restricting portion of the coupling insertion portion 78A. The present invention can obtain the same effect as that obtained by the above-described embodiment even with such a configuration.

(2-2) Other embodiment 2
In the above-described embodiment, the case where the torsion spring 92 is attached to the drum unit coupling 77 provided on the photosensitive drum 25 and the rotation restricting portion 55CY and the rewind restricting portion 78AY are provided on the drum unit 50 has been described.

  However, the present invention is not limited to this, and various configurations different from the configuration according to the above-described embodiment can be applied to the developing unit 52. Accordingly, the drum unit can be applied to the developing unit 52 according to the configuration. Similarly to the 50 side, a rotation restricting portion and a rewind restricting portion may be provided together with the torsion spring.

  That is, in the present invention, in the developing unit 52, the surface of the first supply roller 65 and the surface of the second supply roller 66 are pressed against the surface of the developing roller 51, and the toner blade 67 is pressed.

  Therefore, in the present invention, for example, the developing roller 51 is directly provided with a developing unit coupling that receives a driving force, and at least one of the first supply roller 65 and the second supply roller 66 has a coupling that receives the driving force. If the developing roller 51 is configured to rotate in a direction opposite to that of the above-described embodiment at a rotational speed faster than the rotational speed of the developing roller 51, the developing roller 51 has a rotational speed faster than a prescribed rotational speed. There is a possibility of rotating in the other direction.

  Therefore, according to the present invention, in the case of such a configuration, in the developing unit 52, a torsion spring is attached to the developing unit coupling 70 provided on the developing roller 51, and the right side frame 58 of the developing unit 52 is provided, as in the drum unit 50 side. If the rotation restricting portion and the rewind restricting portion are provided on the developing roller 51, the developing roller 51 can be stabilized at a specified rotation speed and rotated in the other rotation direction.

  Further, in the present invention, for example, at least one of the first supply roller 65 and the second supply roller 66 is provided with a coupling that receives a driving force on the roller rotation shaft, and makes one rotation opposite to the above-described embodiment. If it is configured to rotate in the direction, an acceleration external force is applied from the developing roller 51, and there is a possibility of rotating at a rotational speed faster than a prescribed rotational speed.

  Therefore, in the case of such a configuration, the present invention attaches a torsion spring to the coupling provided on the first supply roller 65 or the second supply roller 66 in the development unit 52 in the same manner as the drum unit 50 side. If the right side frame 58 is provided with a rotation restricting portion and a rewind restricting portion, the first supply roller 65 and the second supply roller 66 can be stabilized and rotated in one rotation direction at a specified rotation speed. .

(2-3) Other Embodiment 3
Further, in the above-described embodiment, the image forming apparatus and the image forming unit according to the present invention are provided in the color printer 1 described above with reference to FIGS. The case where the present invention is applied to the image forming units 14 to 17 has been described.

  However, the present invention is not limited to this, and an image forming apparatus for forming a printed image such as a monochrome electrophotographic printer, a multifunction printer, a facsimile machine, a multifunction peripheral, and a copying machine, and a removable image forming apparatus are provided. The present invention can be widely applied to various image forming units.

(2-4) Other Embodiment 4
Furthermore, in the above-described embodiment, the photosensitive drum described above with reference to FIGS. 1 to 20 is provided as a rotating body that is provided so as to be rotatable in a predetermined rotating direction via a rotating shaft and carries a developer for image formation on the surface. The case where 25 is applied has been described.

  However, the present invention is not limited to this, and a drum body formed by providing a photosensitive layer having a predetermined thickness such as selenium or amorphous silicon on the outer peripheral surface of a conductive substrate such as drum-shaped aluminum. An organic photosensitive layer having a predetermined thickness formed by dispersing a charge generating agent and a charge transporting agent in a binder resin is provided on the outer peripheral surface of an inorganic photosensitive drum having a portion or a conductive substrate such as drum-shaped aluminum. An organic photosensitive drum having a drum main body formed as described above and a photoconductor having a drum main body formed by providing a photoconductive layer on the outer peripheral surface of a cylindrical conductive substrate can be applied.

  The present invention also provides the developing roller 51, the first supply roller 65, the second supply roller 66, one driving roller provided with a coupling, one or a plurality of driven rollers, and these driving rollers as rotating bodies. An endless photosensitive belt stretched around a driven roller, one driving roller provided with a coupling, and one or a plurality of driven rollers, and an endless developing belt stretched around the driving roller and the driven roller, Essentially, it is driven through the coupling, such as one driving roller provided with a coupling, one or more driven rollers, and an endless supply belt stretched around these driving rollers and driven rollers. As long as the rotating body is rotated by receiving a force and an acceleration external force is applied during the rotation, the rotating body of various other configurations can be widely applied.

(2-5) Other Embodiment 5
Furthermore, in the above-described embodiment, the drum unit coupling 77 described above with reference to FIGS. 1 to 20 is applied as a coupling that is provided at one end of the rotating shaft so as to rotate integrally with the rotating body and receives a driving force. The case was described as above.

  However, the present invention is not limited to this, and the shape of the engaging portion 77A is different from that of the developing unit coupling 70 and the drum unit coupling 77 described above as long as it is provided at one end of the rotating shaft and can be attached with a torsion spring. Various other configurations such as a drum unit coupling can be widely applied.

(2-6) Other embodiment 6
Further, in the above-described embodiment, the case where the torsion spring 92 described above with reference to FIGS. 1 to 20 is applied as the torsion spring attached to the coupling by tightening the annular portion has been described.

  However, the present invention is not limited to this, and the above-described torsion spring 92 is formed by winding a metal wire in a reverse direction to form a spring annular portion, and positioning one end closer to the shaft end surface of the rotating shaft than the other end. Various other configurations of torsion springs such as a torsion spring attached to the coupling can be widely applied.

(2-7) Other Embodiment 7
Further, in the above-described embodiment, when the coupling receives a driving force and the rotating body rotates in the rotation direction together with the coupling, the rotation restriction unit restricts the rotation of the torsion spring in the rotation direction. The case where the rotation restricting portion 55CY described above with reference to FIGS. 1 to 20 is applied has been described.

  However, the present invention is not limited to this, and various other types of rotation restricting portions such as a rotation restricting portion provided in the coupling insertion portion 78A of the cover 78 can be widely applied.

(2-8) Other embodiment 8
Further, in the above-described embodiment, the rewinding restricting portion that is disposed to face the outer surface of the annular portion of the torsion spring and restricts the rewinding of the torsion spring when the rotation restricting portion restricts the rotation of the torsion spring. As described above, the case where the plurality of rewinding restricting portions 78AY described above with reference to FIGS. 1 to 20 is applied has been described.

  However, the present invention is not limited to this, and the inner surface 78AX of the coupling insertion portion 78A of the cover 78, the right side frame 55 of the drum unit 50 (for example, the inner surface of the partition plate 55C), the spring annular portion 92A of the torsion spring 92 is provided. Various other configurations of the unwinding restricting part such as at least one unwinding restricting part provided to face the outer surface can be widely applied.

(2-9) Other Embodiment 9
Furthermore, in the above-described embodiment, the case where the coupling insertion portion 78A provided in the cover 78 described above with reference to FIGS. 1 to 20 is applied as the coupling insertion portion into which the coupling is inserted has been described. .

  However, the present invention is not limited to this, and other various coupling insertion portions such as a coupling insertion portion provided in the right side frame 55 of the drum unit 50 can be widely applied.

(2-10) Other Embodiment 10
Further, in the above-described embodiment, the rotating shaft of the rotating body is illustrated as a support portion that rotatably supports a predetermined support position closer to the other end than the one end portion inserted into the shaft insertion hole portion of the coupling. The case where the left side frame 54 and the right side frame 55, the left bearing portion 88, and the right bearing portion 89 of the drum unit 50 described above with reference to FIGS.

  However, the present invention is not limited to this, and the support portions having various other configurations such as the drum storage frame 53 and the left bearing portion 88 and the right bearing portion 89 provided in the drum storage frame 53 are widely applied. be able to.

  The present invention relates to an image forming unit provided in an image forming apparatus such as a color electrophotographic printer, a monochrome electrophotographic printer, a multi-function printer, a facsimile, a multifunction peripheral, and a copying machine, and the color electrophotographic printer, It can be used for image forming apparatuses such as monochrome electrophotographic printers, multi-function printers, facsimile machines, multifunction machines, and copiers.

  DESCRIPTION OF SYMBOLS 1 ... Color printer, 14 thru | or 17 ... Image forming unit, 25 ... Photosensitive drum, 50 ... Drum unit, 51 ... Developing roller, 51A ... Roller rotating shaft, 52 ... Developing unit, 55, 58 ... Right side frame, 55C ... partition plate, 55CX ... rotation restricting portion, 70 ... developing unit coupling, 77 ... drum unit coupling, 78 ... cover, 78A ... coupling insertion portion, 78AX ... inner surface, 78AY ... rewinding restricting part, 86 ... drum rotating shaft, 92 ... torsion spring, 92A ... spring annular part, 92B ... one end of spring.

Claims (9)

A rotating body that is rotatably provided in a predetermined rotating direction via a rotating shaft and carries a developer for image formation on the surface;
A coupling provided at one end of the rotating shaft so as to rotate integrally with the rotating body and receiving a driving force;
A torsion spring attached to the coupling so as to tighten an annular portion;
A rotation restricting portion for restricting rotation of the torsion spring in the rotational direction when the coupling receives the driving force and the rotating body rotates in the rotational direction together with the coupling;
An image provided with an unwinding restricting portion that is disposed to face the outer surface of the annular portion of the torsion spring and restricts the unwinding of the torsion spring when the rotation restricting portion restricts the rotation of the torsion spring. Forming unit. A coupling insertion portion into which the coupling is inserted;
The rewinding restricting unit is
The image forming unit according to claim 1, wherein the image forming unit is provided on an inner surface of the coupling insertion portion facing an outer surface of the annular portion of the coupling. The rewinding restricting unit is
The image forming unit according to claim 2, wherein the image forming unit is provided on the inner surface of the coupling insertion portion in a rib shape parallel to a longitudinal direction of the coupling. The rewinding restricting unit is
When the torsion spring is not rewound, the protruding surface facing the outer surface of the annular portion is provided on the inner surface of the coupling insertion portion so that a gap narrower than the spring wire diameter is formed from the outer surface. The image forming unit according to claim 3. The coupling insertion part is
5. The image forming unit according to claim 2, wherein the coupling is guided when the driving unit that applies the driving force to the coupling and the coupling are coupled. 6. The coupling is
The one end of the rotating shaft is inserted into the shaft insertion hole and provided at the one end,
The torsion spring is
The said annular part is attached with respect to the said coupling so that the said annular part may relate to the insertion position of the said one end part of the said rotating shaft inserted in the said shaft insertion hole part. The image forming unit according to claim 4 or 5. A support unit that rotatably supports the rotation shaft of the rotating body at a predetermined support position closer to the other end than the one end inserted into the shaft insertion hole of the coupling;
The coupling is
The one end of the rotating shaft is inserted into the shaft insertion hole and provided at the one end,
The torsion spring is
The said annular part is attached with respect to the said coupling so that the said annular part may relate to the insertion position of the front-end | tip part of the said one end part of the said rotating shaft inserted in the said shaft insertion hole part. The image forming unit according to claim 4, claim 5, or claim 6. The rotating body is
An image carrier that carries the developer as a developer image on the surface. Claim 1, Claim 2, Claim 3, Claim 4, Claim 6, or Claim 7 The image forming unit described. An image forming apparatus comprising the image forming unit according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, or claim 8.

Images