JP5583923B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus including a developing unit used in an image forming apparatus such as a copying machine or a printer which prints an image on a medium.

  In general, an image forming unit used in an electrophotographic printer is detachably attached to a printer, and a developing roller that forms a toner image on a photosensitive drum and a toner thin film on the surface by pressing the developing roller. And a developing blade for forming a layer.

  Since such an image forming unit always presses the developing roller with a predetermined pressing force by the developing blade even when stored without being mounted on the printer, the developing blade on the surface of the developing roller becomes longer as the storage period becomes longer. This causes a problem that the portion pressed by the deformation is deformed, a horizontal stripe is formed in the printed image, and the image quality is deteriorated.

  Therefore, a conventional electrophotographic printer includes a developing roller that forms a toner image on a photosensitive drum, and a developing blade that presses the developing roller to form a thin layer of toner on the surface thereof. An eccentric cam that moves the axis of the rotation shaft of the developing roller in the image forming unit, a gear that rotates the eccentric cam, an operation bar that is formed with a rack that meshes with this gear, and the operation bar in two vertical positions Two locking grooves are provided to lock the image forming unit. When the image forming unit is stored, the operating rod is pulled upward to retract the developing roller from the developing blade, and when installed, the operating rod is pushed upward to press the developing blade against the developing roller. Thus, deformation of the developing roller during storage is prevented. (For example, refer to Patent Document 1).

JP 2002-323017 A (mainly paragraphs 0029, 0030, 0033-0037, FIG. 14)

  However, in the above-described conventional technique, using an eccentric cam that moves the axis of the rotation shaft of the developing roller, a gear that rotates the eccentric cam, and an operation rod that is formed with a rack that meshes with the gear, Since the pressing force of the developing blade is changed, there is a problem that the configuration becomes complicated and the manufacturing cost increases.

  Further, if the processing accuracy of the eccentric cam, the gear, the rack formed on the operation rod, and the two lock grooves for locking the operation rod at two positions in the vertical direction is not increased, the pressing force of the developing blade at the time of mounting Further, there is a problem that the pressing angle is not stable, and the thickness of the toner thin layer formed on the surface of the developing roller varies and the image quality is deteriorated.

  The present invention has been made to solve the above-described problems, and has means for enabling a reduction in the pressing force of the developing blade (regulating member) during storage of the image forming unit (developing unit) with a simple configuration. The purpose is to provide.

In order to solve the above-described problems, the present invention includes an apparatus housing, a developer carrier, and a regulating member formed of an elastic material that presses the surface of the developer carrier at one end. An image forming apparatus comprising: a developing unit that is detachably attached to a housing; and a developer cartridge that contains developer and is detachably attached to a unit housing of the developing unit. A holding member that holds the other end of the member and changes the pressing force of the restricting member into a first pressing force and a second pressing force that is lower than the first pressing force, and provided in the unit housing A first restricting member and a second restricting member for contacting the other end of the holding member to restrict the pressing force of the restricting member, and the other end of the holding member. an elastic member for pressing the provided, the coercive of the first limiting member A cylindrical portion having a height less than the thickness of the holding member on the root side between the abutting portion with which the other end of the member abuts and a support portion which is an end portion on the opposite side of the abutting portion; A positioning pin having a conical taper surface formed on the tip side is provided, and a positioning hole is provided in the holding member to be fitted to a cylindrical portion of the positioning pin, and the developer cartridge to the unit housing of the developing unit is provided. Regardless of whether or not it is attached, the holding member is supported by the support portion of the first restricting member and guided to the tapered surface of the positioning pin, and the holding member is rotated by the elastic force of the restricting member. The other end of the holding member is brought into contact with the second restricting member to generate the second pressing force, and the developing unit is attached to the developing device in a state where the developer cartridge is mounted on the developing unit. when it is attached to, before The holding member by the pressing force by the elastic member by guiding the tapered surface of the positioning pin while supporting said holding member by the support portion of the first limiting member is rotated, the positioning hole of the holding member fitted into the cylindrical portion of the positioning pin is brought into contact with the other end of the holding member before Symbol first limiting member performs positioning, characterized in that generating said first pressing force.

  As a result, the present invention can reduce the pressing force applied to the developer carrier by the regulating member during storage of the development unit with a simple configuration, prevent deformation of the surface of the developer carrier, and The effect that quality can be improved is acquired.

Explanatory drawing which shows the side of schematic structure of the printer of Example 1. FIG. Explanatory drawing which shows the cross section of the image forming unit of Example 1. FIG. 3 is an explanatory diagram illustrating an appearance of the toner cartridge according to the first exemplary embodiment. Explanatory drawing which shows the external appearance of the image forming unit of Example 1. FIG. 3 is a perspective view showing the inside of the image forming unit of Embodiment 1. The partial expansion perspective view which shows the B section of FIG. Explanatory drawing which shows the state of the image development blade at the time of upper frame closing of Example 1. FIG. FIG. 8 is a partially enlarged plan view showing the inside of the image forming unit viewed from the direction of arrow C in FIG. Explanatory drawing which shows the action | operation of the image development blade of Example 1. FIG. FIG. 3 is an explanatory view showing a plane of an image forming unit equipped with a toner cartridge as viewed from the direction of arrow D in FIG. Explanatory drawing which shows the action | operation of the image development blade of Example 2. Explanatory drawing which shows the plane of the image forming unit which mounted the toner cartridge of Example 2. FIG. Explanatory drawing which shows the state of the developing blade at the time of toner cartridge mounting of Example 2 Explanatory drawing which shows the side of schematic structure of the printer of Example 3. FIG. Explanatory drawing which shows the state of the developing blade at the time of image forming unit mounting of Example 3 FIG. 15 is a partially enlarged plan view showing the inside of the image forming unit as seen from the direction of arrow E in FIG. Explanatory drawing which shows the action | operation of the image development blade of Example 3. Explanatory drawing which shows the action | operation of the image development blade of Example 3.

  Embodiments of an image forming unit and an image forming apparatus according to the present invention will be described below with reference to the drawings.

  In FIG. 1, reference numeral 1 denotes an electrophotographic printer as an image forming apparatus. A sheet conveyance path 4 having a plurality of conveyance rollers 3 and the like is provided in an apparatus housing 2 composed of an upper frame 2a and a lower frame 2b. It is generally arranged in an S shape.

  The upper frame 2a and the lower frame 2b are connected so as to be openable and closable by a hinge portion 5 provided at one end of each of the upper frame 2a and the lower frame 2b. Is disposed at one end of the sheet conveying path 4 and a sheet feeding section 7 for feeding sheets from the sheet feeding cassette 6 to the sheet conveying path 4 one by one. In addition, a stacker 9 is provided on the upper surface of the upper frame 2a to stack sheets of paper that have been printed out from a discharge roller 8 provided at the other end of the sheet conveyance path 4.

  A thickness detector 10 that detects the thickness of the paper fed from the paper feed cassette 6 along the paper conveyance direction and the fed paper are attached to the paper conveyance path 4 by an electrostatic effect. A transfer belt 11 to be conveyed and a fixing device 12 for fixing a toner image as a developer image on a sheet by pressure and heat are sequentially arranged, and a transfer device arranged between the thickness detection unit 10 and the fixing device 12 is arranged. Development that contains toner as developer of K color (black), Y color (yellow), M color (magenta), and C color (cyan) at positions facing the belt 11 across the paper conveyance path 4 An image forming unit 14 as a developing unit equipped with a toner cartridge 13 as an agent cartridge is arranged along the transport direction.

  Reference numeral 15 denotes a cam mechanism, which is disposed on both sides of the transfer belt 11 in the direction orthogonal to the conveyance direction (the depth direction in FIG. 1), and is an actuator such as a linear solenoid or a stepping motor disposed on the upstream side in the conveyance direction. It is driven by 15a.

  Reference numeral 16 denotes an exposure head as an exposure unit, which is configured by arranging a plurality of light emitters that emit light such as LEDs (Light Emitting Diodes) in a line, and is disposed so as to face above a photosensitive drum 19 (described later). The surface of the photosensitive drum 19 is exposed by the light of, thereby forming an electrostatic latent image.

  Reference numeral 17 denotes a transfer roller as transfer means, which is disposed opposite to the lower side of the photosensitive drum 19 with a sheet conveyed through the sheet conveying path 4, and is rotated independently of the photosensitive drum 19 by a driving source (not shown). It has a function of driving and transferring a toner image formed on the surface of the photosensitive drum 19 onto a sheet.

  As shown in FIG. 2, the image forming unit 14 of the present embodiment has a unit casing composed of an upper cover 14 a and a lower cover 14 b, and is orthogonal to the conveying direction of the lower cover 14 b (longitudinal direction of the photosensitive drum 19). Around the photosensitive drum 19 as an image carrier rotatably supported by side frames 18 (see FIG. 4) provided on both sides of the toner, a charging roller 20 as a charging means and development as a developer carrier A roller 21, a supply roller 22 as a developer supply means, a developing blade 23 as a regulating member, a cleaning blade 26 as a cleaning member, and the like are arranged, and the upper frame 2a of the printer 1 is opened to remove the lower frame 2b. It is detachably mounted at a predetermined position.

  The photosensitive drum 19 is a cylindrical member in which a photoconductive layer is formed on the surface of a conductive support made of a metal pipe or the like, and both end portions of the rotary shaft 19a provided on the axis of the photosensitive drum 19 are connected to the lower cover 14b. A gear 19b (see FIG. 8) provided at one end in the longitudinal direction of the photosensitive drum 19 is not shown, and is protruded from the side frame 18 provided on both sides and rotatably supported (see FIGS. 4 and 5). It is rotationally driven by a drive source such as a drive motor.

  Further, the projecting portion of the rotating shaft 19a from the side frame 18 is supported by side wall guides, which are U-shaped grooves formed on the side walls of both ends of the lower frame 2b, on both sides of the outer circumferential surface in the transport direction, and the outer periphery of the projecting portion. The lower surface is supported by the cam surface of the cam mechanism 15, and when the cam surface of the cam mechanism 15 is moved in the paper transport direction by the actuator 15 a, the entire image forming unit 14 is lifted upward, and the photoconductor The position of the drum 19 in the height direction moves.

  The charging roller 20 is formed by coating a metal rotating shaft 20a with a semiconductive rubber layer, and has a function of following the rotation of the photosensitive drum 19 to uniformly charge the photosensitive drum 19. ing.

  The developing roller 21 is formed by coating a metal rotating shaft 21a with a semiconductive rubber material such as urethane rubber, and meshes with a gear 21b (see FIG. 9) provided on the rotating shaft 19a of the photosensitive drum 19. 6, 8), and rotates in the opposite direction while contacting the photosensitive drum 19, and forms a toner image by attaching toner to the electrostatic latent image formed by the exposure head 16 on the photosensitive drum 19. Have.

  The supply roller 22 is formed by coating a foamed rubber material on a metal rotating shaft 22a, and is in contact with the developing roller 21 by a driving force transmitted from a gear 21b provided on the rotating shaft 21a of the developing roller 21. And has a function of supplying the toner from the toner cartridge 13 to the developing roller 21.

  The developing blade 23 is formed by bending the tip of an elastic material having elasticity, such as a stainless steel plate formed so that the length in the longitudinal direction is longer than the length in the direction perpendicular to the conveyance direction of the maximum size paper used for printing. A thin plate having an L-shaped cross-section formed, and an end opposite to the tip is sandwiched and held between a holder 24 and a blade presser 25 as a holding member fastened with a screw or the like. The back surface of the bent portion formed in the portion is in sliding contact with the surface of the developing roller 21 and has a function of reducing the toner thickness to a predetermined thickness by the pressing force and frictionally charging the toner. ing.

  The cleaning blade 26 is formed of a rubber-like elastic body, has its tip pointed in a direction opposite to the rotation direction of the photosensitive drum 19, and presses the outer peripheral surface of the photosensitive drum 19 with a predetermined pressing force. The toner remaining on the outer peripheral surface of the photosensitive drum 19 after the image is transferred has a function of scraping and removing the toner at the edge portion at the tip that is in sliding contact with the outer peripheral surface.

  As shown in FIG. 2, the toner cartridge 13 of the present embodiment is detachably mounted on the cartridge mounting portion 28 of the upper cover 14a of the unit housing. As shown in FIG. A developer discharge port 29 that is a rectangular long hole that is opened and closed by a formed shutter (not shown) is provided, and is rotated by a drive system (not shown) in the vicinity of the developer discharge port 29 in the toner chamber 13a of the toner cartridge 13. A stirring bar 30 (see FIG. 2) is provided.

  As a result, when the open / close lever 31 formed integrally with the end of the shutter is rotated in the direction of arrow A shown in FIG. 3 when the toner cartridge 13 is mounted in the image forming unit 14, the developer discharge port 29 is opened. The toner in the toner chamber 13 a is supplied from the developer discharge port 29 to the inside of the image forming unit 14 by the stirring bar 30 that is rotated by driving in the printing operation.

  Further, the toner cartridge 13 is provided with a waste toner collecting portion 32 (see FIG. 2) adjacent to the toner chamber 13a, and the waste toner scraped off from the surface of the photosensitive drum 19 by the cleaning blade 26 is an image. The waste toner is transported to a waste toner discharge port 34 (see FIG. 4) formed on the side frame 18 of the lower cover 14b by a transport spiral 33 (see FIG. 3) as a waste toner transport means provided in the forming unit 14. The toner is discharged and collected from the collection port 32a (see FIGS. 2 and 3) of the waste toner collection unit 32 fitted to the discharge port 34.

  As shown in FIGS. 5 and 6, the holders 24 for holding the developing blade 23 of the present embodiment between the blade presser 25 are provided on both sides in the longitudinal direction of the lower cover 14b of the unit housing of the image forming unit 14. A blade fixing portion 24a formed of a metal plate having a length in the longitudinal direction equivalent to the distance between the side frames 18 formed, and an extending portion that integrally extends from both ends of the blade fixing portion 24a are formed in a "<" shape. And an arm portion 24b (see FIG. 7) formed by bending it.

  Sponge seals 35 are disposed at both ends of the developing roller 21 and the supply roller 22 to seal toner leakage from these ends (see FIG. 8).

  At the center in the extending direction of the arm portion 24b of the holder 24, a predetermined position on the side frame 18 side of the step portion 37 as the first restricting member formed at the edge portion of the roller storage portion 36 of the lower cover 14b. A positioning hole 39 (see FIG. 9) into which the formed positioning pin 38 (see FIGS. 8 and 9) is fitted is provided.

  Further, the upper surface of the tip of the arm portion 24b opposite to the blade fixing portion 24a across the positioning hole 39 is on the side walls on both sides in the transport direction of the upper frame 2a of the printer 1, respectively. A free end on the opposite side of the attachment end of the compression coil spring 42 as an elastic member attached to the support member 41 fixed in correspondence with is arranged.

  As shown in FIG. 7, the compression coil spring 42 is provided on the side frame 18 side of the bottom plate 28 a of the cartridge mounting portion 28 of the upper cover 14 a of the image forming unit 14 when the upper frame 2 a of the printer 1 is closed. As a second limiting member provided integrally with the upper cover 14a between the through hole 44 (see FIG. 4) and the bottom plate 28a of the cartridge mounting portion 28 of the upper cover 14a and the step portion 37 of the lower cover 14b. The stopper plate 45 (see FIG. 5) is inserted into the insertion hole 46 to press the upper surface of the tip of the arm portion 24b of the holder 24.

  Further, as shown in FIG. 10, a relief portion 47 for inserting the compression coil spring 42 is provided at a corner portion on the toner chamber 13 a side opposite to the opening / closing lever 31 of the toner cartridge 13.

  When the upper frame 2a is closed, the urging force of the compression coil spring 42 resists the force in the direction in which the arm portion 24b tends to move away from the step surface of the step portion 37 by the elastic force of the developing blade 23. The force is set so that the lower surface of 24 b can be pressed against the step surface of the stepped portion 37.

  As shown in FIG. 9, the positioning pin 38 is formed with a cylindrical portion 38a having a height less than the thickness of the arm portion 24b on the root side, and with a conical tapered surface 38b on the tip side. When the lower surface of the arm portion 24b of the holder 24 is in contact with and locked to the step surface of the step portion 37 (two-dot chain line shown in FIG. 9), the cylindrical portion 38a is fitted into the positioning hole 39. Then, the holder 24 is positioned, and the surface of the tip of the developing blade 23 held by the holder 24 presses the surface of the developing roller 21 with a predetermined pressing force (first pressing force). By rotation in operation, a thin layer of toner of a predetermined thickness is formed on the surface.

  Further, when the pressing by the compression coil spring 42 to the distal end portion of the arm portion 24b is released (solid line shown in FIG. 9), the holder 24 guides the tapered surface 38b of the positioning pin 38 by the elastic force of the developing blade 23 itself. , The corner of the tip of the arm portion 24b is brought into contact with and locked to the lower surface of the stopper plate 45, and the back surface of the tip of the developing blade 23 held by the holder 24 is the surface of the developing roller 21. Is pressed with a second pressing force which is lower than a predetermined pressing force (first pressing force) and which does not cause deformation due to creep or the like on the rubber material coated on the surface of the developing roller 21.

  The operation of the above configuration will be described.

  When the stored image forming unit 14 is mounted on the printer 1 and a printing operation is performed, the toner containing a predetermined color in the cartridge mounting portion 28 of the upper cover 14a of the stored image forming unit 14 When the cartridge 13 is mounted and the open / close lever 31 formed integrally with the shutter of the toner cartridge 13 is rotated in the direction of arrow A (see FIG. 3), the developer discharge port 29 is opened.

  At this time, the developing blade 23 held by the holder 24 is in a position indicated by a solid line in FIG. 9, that is, a position where the tip of the arm portion 24b is locked to the lower surface of the stopper plate 45 by the elastic force of the developing blade 23. The surface of the developing roller 21 is pressed with a second pressing force.

  Next, when the upper frame 2a of the printer 1 is opened, the image forming unit 14 is mounted at a predetermined position of the lower frame 2b, and the upper frame 2a is closed, the upper frame 2a is attached to the support member 41 fixed to the upper frame 2a. One of the compression coil springs 42 is inserted into the escape portion 47 of the toner cartridge 13, the through hole 44 of the cartridge mounting portion 28, and the insertion hole 46 of the stopper plate 45 (see FIG. 10), and the other is the open / close lever of the cartridge mounting portion 28. 31 is inserted into the side hole 31, the through hole 44, and the insertion hole 46 (see FIG. 7), and the free end thereof presses the tip end portion of the arm portion 24 b of the holder 24 to be inserted into the positioning hole 39 of the arm portion 24 b. The holder 24 is guided by the tapered surface 38b of the positioning pin 38, as shown by a two-dot chain line in FIG. 9, that is, the arm portion 24b. The end portion is pressed by the pressing force of the compression coil spring 42, and the lower surface thereof is rotated to a position where it is locked to the step surface of the step portion 37, so that the holder 24 is aligned with the cylindrical portion 38 a of the positioning pin 38 and the positioning hole 39. The developing blade 23 held by this is pressed against the surface of the developing roller 21 with a predetermined pressing force (first pressing force).

  When the user transmits print information of the printed matter from an external personal computer or the like to the printer 1, the printer 1 that has received this starts a printing operation and feeds the paper in the paper feed cassette 6 to the paper transport path 4. The photosensitive drum 19 and the charging roller 20 of each image forming unit 14 are rotated and the photosensitive drum 19 is uniformly charged by the charging roller 20 having a predetermined charge. Then, print data generated in accordance with each color based on the received print information is sent to each exposure head 16, and light is irradiated from the exposure head 16 to the surface of the photosensitive drum 19, so that the surface of each photosensitive drum 19 is irradiated. An electrostatic latent image of each color is formed, and a thin layer of toner formed on the surface of the developing roller 21 when the developing blade 23 is pressed with a predetermined pressing force is rotated while contacting. The electrostatic latent image on the photosensitive drum 19 is developed and adhered, and the toner images are sequentially transferred onto the paper by the transfer roller 17 to form an image on the paper. The paper that has been fixed by the fixing device 12 and finished printing is discharged onto the stacker 9 of the printer 1 by the discharge roller 8.

  As described above, the image forming unit 14 according to the present embodiment is provided with the positioning hole 39 in the center portion of the arm portion 24b formed by bending the extending portion formed at both ends in the longitudinal direction of the holder 24 holding the developing blade 23, and positioning the positioning hole 39. The hole 39 is fitted and attached to the positioning pin 38 provided on the step portion 37 on the side frame 18 side of the lower cover 14b, and the positioning pin 38 is guided by the elastic force of the developing blade 23 when the image forming unit 14 is stored. The tip of the rotating arm portion 24b is engaged with the lower surface of the stopper plate 45 provided on the upper cover 14a, so that the pressing force applied to the surface of the developing roller 21 by the developing blade 23 is lower than a predetermined pressing force. When the upper frame 2a is closed after being attached to the printer 1, the upper end of the compression coil spring 42 provided on the upper frame 2a The front end of the groove portion 24b is pressed, the positioning hole 39 is fitted into the positioning pin 38 to position the holder 24, and the arm portion 24b is locked to the stepped portion 37 so that the developing roller 23 can Since the pressing force on the surface is a predetermined pressing force (first pressing force), the pressing force applied to the developing roller 21 by the developing blade 23 during storage of the image forming unit 14 can be reduced with a simple configuration. Even if the storage period becomes longer, deformation of the surface of the developing roller 21 can be prevented and image quality can be improved.

  Further, since the developing roller 21 is pressed with a low pressing force by the developing blade 23 even when the image forming unit 14 is stored, it is possible to prevent the generation of abnormal noise when the image forming unit 14 is transported or moved. Is possible.

  Further, an eccentric cam that moves the axis of the rotation shaft of the developing roller 21, a gear that rotates the eccentric cam, an operation bar that is formed with a rack that meshes with the gear, The pressing force of the developing blade can be made variable with a simple configuration without providing two lock grooves or the like that are locked at two positions, and the manufacturing cost of the image forming unit 14 can be reduced.

  Further, the tapered surface 38b for guiding the movement of the positioning hole 39 of the holder 24 is formed on the distal end side of the positioning pin 38, and the cylindrical portion 38a for fitting the positioning hole 39 is formed on the root side. The holder 24 can be positioned accurately by fitting the cylindrical portion 38a and the positioning hole 39, and the pressing force and the accuracy of the pressing angle when the image forming unit 14 is mounted can be moved smoothly. Thus, the thickness of the thin toner layer formed on the surface of the developing roller 21 can be stabilized.

  As described above, in this embodiment, arm portions having positioning holes formed at both ends of a holder for holding a developing blade made of an elastic material that forms a thin layer of toner on the surface of the developing roller are provided. Is fitted with a positioning pin provided on the step portion of the lower cover, and during storage, the arm portion is rotated with the positioning pin as a guide by the elastic force of the developing blade, and the tip of the stopper plate provided on the upper cover ( The second pressing member is locked to a second pressing force that is lower than a predetermined pressing force by the developing blade, and is attached to the printer 1 by the free end of the compression coil spring provided in the upper frame. The tip of the arm is pressed, the positioning hole is fitted to the positioning pin to position the holder, and the arm is locked to the stepped portion (first limiting member) to By making the pressing force by the roller a predetermined pressing force (first pressing force), the pressing force applied to the developing roller by the developing blade during storage of the image forming unit can be reduced with a simple configuration. In addition, deformation of the surface of the developing roller can be prevented and image quality can be improved.

  In the description of the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The holder 24 for holding the developing blade 23 of this embodiment between the blade presser 25 is formed in the same shape as in the first embodiment, and as shown in FIG. 11, the tip of the arm portion 24b of the holder 24 is formed. Is provided with a projection 52 for attaching a compression coil spring 51 as an elastic member, and the holder 24 is rotated with the taper surface 38b of the positioning pin 38 as a guide by the elastic force of the developing blade 23 itself. As shown by the solid line in FIG. 11, the compression coil spring 51 attached to the protrusion 52 is fixed to the stopper plate 45 when the corner of the tip of the arm portion 24b is in contact with and locked to the lower surface of the stopper plate 45. Through the through hole 44 (see FIG. 12) provided on the side frame 18 side of the bottom plate 28a of the cartridge mounting portion 28 of the upper cover 14a, The free end of which is formed so as to protrude on the bottom plate 28a of the cartridge mounting portion 28.

  Therefore, in this embodiment, when the toner cartridge 13 is not mounted on the cartridge mounting portion 28, that is, when the free end of the compression coil spring 51 is open, the elastic force of the developing blade 23 causes the holder 24 to The tip of the arm 24b is brought into contact with and locked with the stopper plate 45, and the back surface of the tip of the developing blade 23 held by the holder 24 applies a predetermined pressing force (first pressing force) to the surface of the developing roller 21. Press with a second pressing force lower than (pressure).

  Further, the opening / closing lever 54 formed integrally with the end of the shutter that opens and closes the developer discharge port 29 of the toner cartridge 13 of the present embodiment is formed in a substantially circular shape as shown in FIG. When the toner cartridge 13 is mounted on the cartridge mounting portion 28 of the upper cover 14a, one of the compression coil springs 51 is compressed by the bottom surface of the toner cartridge 13, and the other is the outer peripheral surface of the opening / closing lever 54, as shown in FIG. The upper surface of each arm portion 24 b of the holder 24 is pressed by the upper surface, and the lower surface of the arm portion 24 b is locked to the step surface of the step portion 37 (first limiting member) and held by the holder 24. The surface of the tip of the developed developing blade 23 presses the surface of the developing roller 21 with a predetermined pressing force (first pressing force).

  For this reason, the urging force of the compression coil spring 51 resists the force in the direction in which the arm portion 24b tends to move away from the step surface of the step portion 37 by the elastic force of the developing blade 23 when the toner cartridge 13 is mounted. The force that can press the lower surface of the arm portion 24 b against the step surface of the step portion 37 is set.

  The operation of the above configuration will be described.

  When the stored image forming unit 14 is mounted on the printer 1 and a printing operation is performed, the toner containing a predetermined color in the cartridge mounting portion 28 of the upper cover 14a of the stored image forming unit 14 When the cartridge 13 is mounted and the open / close lever 54 formed integrally with the shutter of the toner cartridge 13 is rotated in the direction of arrow A (see FIG. 3), the developer discharge port 29 is opened.

  At this time, the developing blade 23 held by the holder 24 is locked to the lower surface of the stopper plate 45 by the elastic force of the developing blade 23 at the position indicated by the solid line in FIG. 11 from the position where the surface of the holder 24 is pressed by the second pressing force, the position indicated by the two-dot chain line in FIG. 11, that is, the compression of the compression coil spring 51 by the bottom surface of the toner cartridge 13 and the opening / closing lever 54, The distal end of the arm portion 24 b is pressed and rotated with the taper surface 38 b of the positioning pin 38 inserted into the positioning hole 39 of the arm portion 24 b as a guide, so that the lower surface of the arm portion 24 b of the holder 24 is in contact with the stepped portion 37. The holder 24 moves to a position where it is locked to the step surface, and the holder 24 is positioned by fitting the cylindrical portion 38a of the positioning pin 38 with the positioning hole 39. Is, the developing blade 23 held thereto presses the surface of the developing roller 21 by a predetermined pressing force (first pressing force).

  Since the subsequent printing operation is the same as that of the first embodiment, the description thereof is omitted.

  As described above, the image forming unit 14 according to the present exemplary embodiment has a compression coil formed on the protrusion 52 provided at the distal end of the arm 24b formed by bending the extending portion formed at both ends in the longitudinal direction of the holder 24 that holds the developing blade 23. The spring 51 is attached and a positioning hole 39 is provided in the center thereof, and the positioning hole 39 is fitted and attached to a positioning pin 38 provided in the stepped portion 37 on the side frame 18 side of the lower cover 14b. During storage, the tip of the arm portion 24b that rotates with the positioning pin 38 guided by the elastic force of the developing blade 23 is engaged with the lower surface of the stopper plate 45 provided on the upper cover 14a, and the compression coil spring 51 is stopped by the stopper. The insertion hole 46 of the plate 45 and the through hole 44 of the bottom plate 28a of the cartridge mounting portion 28 of the upper cover 14a are inserted. The leading end is protruded into the cartridge mounting portion 28, and the pressing force of the developing blade 23 onto the surface of the developing roller 21 is set to a second pressing force lower than a predetermined pressing force, so that the toner cartridge 13 is moved to the image forming unit 14. At the time of mounting, the free end of the compression coil spring 51 projected into the cartridge mounting portion 28 is compressed by the toner cartridge 13 to press the tip end of the arm portion 24b, and the positioning hole 39 is fitted to the positioning pin 38 to hold the holder. 24 is positioned, and the arm portion 24b is locked to the step portion 37 so that the pressing force applied to the surface of the developing roller 21 by the developing blade 23 is set to a predetermined pressing force (first pressing force). With this configuration, it is possible to reduce the pressing force applied to the developing roller 21 by the developing blade 23 when the image forming unit 14 is stored. Even storage period is longer, to prevent deformation of the surface of the developing roller 21, it is possible to improve image quality.

  Further, since the developing roller 21 is pressed with a low pressing force by the developing blade 23 even when the image forming unit 14 is stored, it is possible to prevent the generation of abnormal noise when the image forming unit 14 is transported or moved. Is possible.

  Further, an eccentric cam that moves the axis of the rotation shaft of the developing roller 21, a gear that rotates the eccentric cam, an operation bar that is formed with a rack that meshes with the gear, The pressing force of the developing blade can be made variable with a simpler configuration without providing two lock grooves or the like that are locked at two positions, and the manufacturing cost of the image forming unit 14 can be reduced.

  As described above, in this embodiment, the compression coil spring is attached to the tip of the arm provided at both ends of the holder that holds the developing blade made of an elastic material that forms a thin layer of toner on the surface of the developing roller. A projection hole is provided, and a positioning hole is formed in the central portion thereof. The positioning hole is fitted to a positioning pin provided in a step portion of the lower cover, and the positioning pin is guided by the elastic force of the developing blade during storage. The arm portion is rotated, the tip thereof is locked to a stopper plate (second limiting member) provided on the upper cover, the free end of the compression coil spring 51 is protruded into the cartridge mounting portion 28, and the developing blade is used. The pressing force is set to a second pressing force lower than a predetermined pressing force, and when the toner cartridge is mounted, the compression coil spring is compressed with the toner cartridge to The tip of the part is pressed, the positioning hole is fitted to the positioning pin to position the holder, and the arm part is locked to the stepped part (first limiting member), and the pressing force by the developing blade is set to a predetermined value. By using the pressing force (first pressing force), the pressing force applied to the developing roller by the developing blade during storage of the image forming unit can be reduced with a simpler configuration, and the surface of the developing roller can be reduced. Image quality can be improved.

  In the description of the present embodiment, the same parts as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 14, a pedestal 62 having compression coil springs 61 as elastic members attached to the side walls on both sides in the direction orthogonal to the conveying direction of the lower frame 2b of the printer 1 of this embodiment is provided for each image forming unit. 14 is fixed correspondingly.

  The holder 24 that holds the developing blade 23 of this embodiment between the blade presser 25 and the side frame 18 provided on both sides in the longitudinal direction of the lower cover 14b of the image forming unit 14 is the same as in the first embodiment. Are formed by bending a blade fixing part 24a formed of a metal plate having a length in the longitudinal direction equivalent to the distance of the above and an extension part integrally extending from both ends of the blade fixing part 24a into a "<" shape. Arm portion 24b.

  As shown in FIGS. 15 and 16, the holder 24 has a fulcrum shaft 64 (see FIG. 16) as a rotation fulcrum rotatably supported by the side frame 18 at the bent portion of the arm portion 24b in the longitudinal direction. The lever part 65 extended in the opposite direction on the same plane as the arm part 24b is fixed to the protruding part of the fulcrum shaft 64 along the side frame 18 and fixed to the side part on both sides of the lower cover 14b. A free end of a compression coil spring 61 attached to a pedestal 62 fixed to the side wall of the lower frame 2b is disposed on the lower surface of the distal end portion of the lever portion 65 disposed outside the frame 18.

  When the holder 24 of this embodiment is in a state where the free end of the compression coil spring 61 is opened when the image forming unit 14 is stored, the holder 24 is elastic as shown in FIG. Rotating about the fulcrum shaft 64 by force, the corner of the tip of the arm portion 24 b is brought into contact with and locked to the lower surface of the stopper plate 45, and the back side surface of the tip of the developing blade 23 held by the holder 24 Presses the surface of the developing roller 21 with a second pressing force lower than a predetermined pressing force (first pressing force).

  When the image forming unit 14 is mounted on the lower frame 2b of the printer 1, as shown in FIG. 18, the free ends of the compression coil springs 61 attached to the pedestal portion 62 of the lower frame 2b are connected to the respective lever portions 65. The developing blade held by the holder 24 is pressed, the holder 24 is rotated about the fulcrum shaft 64, and the lower surface of the arm portion 24 b is brought into contact with the stepped surface of the stepped portion 37. The surface of the front end portion 23 presses the surface of the developing roller 21 with a predetermined pressing force (first pressing force).

  For this reason, the urging force of the compression coil spring 61 is such that the arm portion 24b tends to move away from the step surface of the step portion 37 by the elastic force of the developing blade 23 when the image forming unit 14 is mounted on the lower frame 2b. The force is set such that the lower surface of the arm portion 24 b can be pressed against the step surface of the step portion 37 against the force.

  The operation of the above configuration will be described.

  When the stored image forming unit 14 is mounted on the printer 1 and a printing operation is performed, the toner containing a predetermined color in the cartridge mounting portion 28 of the upper cover 14a of the stored image forming unit 14 The cartridge 13 is mounted, and the image forming unit 14 with the toner cartridge 13 mounted is mounted on the lower frame 2 b of the printer 1.

  At this time, the developing blade 23 held by the holder 24 is locked to the lower surface of the stopper plate 45 by the elastic force of the developing blade 23 at the position shown in FIG. 18 from the position where the second pressing force is pressed, that is, the free end of the compression coil spring 61 attached to the pedestal 62 of the lower frame 2b, as shown in FIG. When pressed, the holder 24 rotates around the fulcrum shaft 64 to move the lower surface of the arm portion 24b to a position where it is locked to the step surface of the step portion 37, and the developing blade 23 held by the holder 24 is moved to the developing roller. The surface of 21 is pressed with a predetermined pressing force (first pressing force).

  Since the subsequent printing operation is the same as that of the first embodiment, the description thereof is omitted.

  During standby before and after the printing operation of the printer 1, the cam mechanism 15 is attracted by the actuator 15a arranged on the upstream side in the transport direction and moved in the direction opposite to the transport direction (right direction in FIG. 14). Then, the protruding portion of the rotating shaft 19a of the photosensitive drum 19 supported on the cam surface of the cam mechanism 15 is moved upward to move the image forming unit 14 from the position during the printing operation to the upper retracted position.

  At this time, the tip end portions of the lever portions 65 arranged outside the side frames 18 on both sides of the lower cover 14 b of the image forming unit 14 are released from the pressing by the compression coil spring 61, and the holder 24 is elastic of the developing blade 23. The force rotates about the fulcrum shaft 64, the tip of the arm portion 24b is locked to the stopper plate 45, and the surface of the tip of the developing blade 23 presses the surface of the developing roller 21 with the second pressing force.

  As described above, the image forming unit 14 according to the present exemplary embodiment has the side frame of the fulcrum shaft 64 provided at the bent portion of the arm portion 24b formed by bending the extending portions formed at both ends in the longitudinal direction of the holder 24 holding the developing blade 23. 18 is provided with a lever portion 65 that extends in the opposite direction of the arm portion 24b, and the arm portion 24b that rotates around the fulcrum shaft 64 by the elastic force of the developing blade 23 when the image forming unit 14 is stored. The front end is locked to the lower surface of the stopper plate 45 provided on the upper cover 14a, and the pressing force applied to the surface of the developing roller 21 by the developing blade 23 is set to a second pressing force lower than a predetermined pressing force. At the time of mounting, the distal end portion of the lever portion 65 is pressed with the free end of the compression coil spring 61 provided on the lower frame 2b to rotate the holder 24 around the fulcrum shaft 64, The arm portion 24b is locked to the step portion 37 so that the pressing force applied to the surface of the developing roller 21 by the developing blade 23 is set to a predetermined pressing force (first pressing force). It becomes possible to reduce the pressing force to the developing roller 21 by the developing blade 23 when the unit 14 is stored, and even if the storage period is extended, the surface of the developing roller 21 is prevented from being deformed, and the image quality is improved. Can be improved.

  Further, while the printer 1 is on standby, the cam mechanism 15 moves the image forming unit 14 from the position during the printing operation to the upper retracted position, and the pressing of the tip of the lever portion 65 by the compression coil spring 61 is released. The tip of the arm portion 24b that rotates about the fulcrum shaft 64 by the elastic force of the developing blade 23 is engaged with the lower surface of the stopper plate 45 provided on the upper cover 14a so that the developing blade 23 applies the surface to the surface of the developing roller 21. Since the pressing force is the second pressing force lower than the predetermined pressing force, the pressing force applied to the developing roller 21 by the developing blade 23 during the mounting of the image forming unit 14 can be lowered, and the developing roller 21 during the mounting. Therefore, even when printing is not performed for a long time, the image quality can be improved.

  Furthermore, since the holder 24 is rotated around a fulcrum shaft 64 supported by the side frame 18 so as to be rotatable, the holder 24 can be smoothly rotated and also locked to the stepped portion 37. The thickness of the thin layer of toner formed on the surface of the developing roller 21 is improved by accurately positioning the holder 24 and improving the accuracy of the pressing force and the pressing angle when the image forming unit 14 is mounted. Can be stabilized.

  As described above, in this embodiment, the arm is formed on the protruding portion from the side frame of the fulcrum shaft provided in the bent portion of the holder that holds the developing blade made of an elastic material that forms a thin layer of toner on the surface of the developing roller. A stopper plate (second limiting member) provided with a lever portion extending in the opposite direction of the head portion, rotating the arm portion about the fulcrum shaft by the elastic force of the developing blade during storage, ) To make the pressing force by the developing blade a second pressing force lower than a predetermined pressing force, and when the printer 1 is mounted, the free end of the compression coil spring provided on the lower frame is the tip of the lever portion. , The arm part is rotated around the fulcrum shaft, the arm part is locked to the step part (first limiting member), and the pressing force by the developing blade is set to a predetermined pressing force (first pressing force). Pressure) As a result, the pressing force applied to the developing roller by the developing blade during storage of the image forming unit can be reduced with a simple configuration, and the surface of the developing roller can be prevented from being deformed to improve the image quality. it can.

  In each of the above-described embodiments, the image forming apparatus is described as a printer. However, the image forming apparatus is not limited to the above, and may be a copier, a facsimile machine, and a multifunction machine including a printer. Good.

DESCRIPTION OF SYMBOLS 1 Printer 2 Apparatus housing 2a Upper frame 2b Lower frame 3 Conveyance roller 4 Paper conveyance path 5 Hinge part 6 Paper feed cassette 7 Paper feeding part 8 Discharge roller 9 Stacker 10 Thickness detection part 11 Transfer belt 12 Fixing device 13 Toner cartridge 13a Toner chamber 14 Image forming unit 14a Upper cover 14b Lower cover 15 Cam mechanism 15a Actuator 16 Exposure head 17 Transfer roller 18 Side frame 19 Photosensitive drum 19a, 20a, 21a, 22a Rotating shaft 19b, 21b Gear 20 Charging roller 21 Developing roller 22 Supply roller 23 Developing blade 24 Holder 24a Blade fixing portion 24b Arm portion 25 Blade presser 26 Cleaning blade 28 Cartridge mounting portion 29 Developer discharge port 31, 54 Open / close lever 30 Stirring Stirring bar 32 Waste toner collection part 32a Collection port 34 Waste toner discharge port 35 Sponge seal 36 Roller storage part 37 Step part 38 Positioning pin 39 Positioning hole 41 Support member 42, 51, 61 Compression coil spring 44 Through hole 45 Stopper plate 46 Insertion Hole 47 Escape part 52 Projection part 62 Base part 64 Support shaft 65 Lever part

Claims (1)

A device housing;
A developing unit having a developer carrying member and a regulating member formed of an elastic material that presses the surface of the developer carrying member at one end, and is detachably attached to the apparatus housing;
In an image forming apparatus comprising: a developer cartridge that contains a developer and is detachably mounted on a unit housing of the developing unit;
A holding member that holds the other end of the restricting member at one end, and changes the pressing force of the restricting member into a first pressing force and a second pressing force lower than the first pressing force;
A first restricting member and a second restricting member, which are provided in the unit casing and restrict the pressing force of the restricting member by contacting the other end of the holding member;
An elastic member attached to the device casing and pressing the other end of the holding member;
Less than the thickness of the holding member on the root side between the abutting portion with which the other end of the holding member of the first limiting member abuts and a support portion which is an end portion on the opposite side of the abutting portion And a positioning pin having a conical taper surface formed on the tip side, and a positioning hole for fitting to the cylindrical portion of the positioning pin are provided in the holding member,
Regardless of whether or not the developer cartridge is attached to the unit housing of the developing unit, the restriction member is guided by the taper surface of the positioning pin while supporting the holding member by the support portion of the first limiting member. Rotating the holding member with the elastic force of the member to bring the other end of the holding member into contact with the second limiting member to generate the second pressing force;
When the developing unit is mounted on the apparatus housing with the developer cartridge mounted on the developing unit, the taper of the positioning pin supports the holding member with the support portion of the first limiting member. The holding member is rotated by the pressing force of the elastic member while being guided to the surface, and the positioning hole of the holding member is fitted to the cylindrical portion of the positioning pin for positioning, and the other end of the holding member is image forming apparatus characterized by pre SL is brought into contact with the first limiting member to generate said first pressing force.

Images