JP4337483B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that can store a plurality of developing units and a developing unit that is stored in the image forming apparatus.

  In recent years, colorization of image forming apparatuses has progressed, and four types of developing units each containing cyan (C), magenta (M), yellow (Y), and black (K) toners are stored in the image forming unit. 2. Description of the Related Art An image forming apparatus provided with a storage unit so that it can be stacked and stored is known (see, for example, Patent Document 1).

  In Patent Document 1, a developing roller is provided in front of the developing unit (photosensitive belt side), and driven gears are provided at both ends of the developing roller. Further, the main body is provided with a driving gear, and meshes with a driven gear provided in the developing unit. As the driving gear rotates, the developing unit moves back and forth, and the developing roller and the photosensitive belt can come into contact with each other. A guide groove is provided in the housing portion of the main body, and guide members are attached to both side portions of the developing unit. The guide member of the developing unit is fitted into the guide groove of the main body to determine the position of the developing unit in the main body.

JP 2002-278209 A

  In a color image forming apparatus, it is necessary to stack and store a plurality of developing units at predetermined positions of the image forming apparatus, which increases the size of the image forming apparatus main body. However, it is desirable that the image forming apparatus is small in size, and therefore, it is conceivable to reduce the size of the developing unit.

  For example, the positioning of the developing unit with respect to the main body in the image forming apparatus configured as in Patent Document 1 is performed by fitting the driven gear provided in front of the developing unit side with the driving gear of the main body and the guide groove. With the combined guide member.

  In such a configuration, the developing unit is thinned. However, if the developing unit is supported only at both ends, the developing unit is bent. It is conceivable to prevent bending by increasing the rigidity, but in order to increase the rigidity, it is necessary to thicken the bottom and top of the developing unit or to reinforce it with a hard member such as a metal plate. Such a development unit having high rigidity may become large in size, become heavy, and may increase the cost. If the size is increased, the developing unit, which is the original purpose, cannot be sufficiently thinned, and if the weight of the developing unit is increased, the mounting operation becomes complicated.

  In order to solve the above problems, an image forming apparatus capable of stacking a plurality of developing units and storing them in a horizontal direction, which is small in size and capable of positioning without developing each of the developing units, and its It is an object of the present invention to provide a developing unit that is housed in an image forming apparatus.

Means for Solving the Problems and Effects of the Invention

The image forming apparatus according to claim 1 includes at least a developer and a developer carrier, and a pair of side portions that rotatably support the developer carrier, a top portion, and the top portion. A plurality of development units each having a bottom portion are stacked in a horizontally detachable storage portion, and an image is formed on a print medium via the developer carrier, the image carrier, the transfer portion, and the fixing portion. In the forming apparatus, the developing units are provided on the both side portions, and a first positioning member that positions the developing unit by contacting the storage portion, and a plurality of developing units provided on the bottom and stacked on the bottom. A second positioning member that positions the developing unit by abutting with the developing unit positioned on the flat surface, and a flat surface that extends in the same direction as the storing direction in the storage portion on the top portion. When the knit is attached / detached, when the abutment part that is slidable in contact with the second positioning member and the other developing unit located under the developing unit are removed from the accommodating part, the accommodating part An auxiliary member capable of contacting the first positioning member, wherein the first positioning member is closer to the developing carrier than the second positioning member, and is between the first positioning member and the second positioning member. The developing unit has a center of gravity.

According to such a configuration, the first positioning member is supported by the storage portion, and the developing unit positioned below by the second positioning member on the opposite side of the first positioning member across the center of gravity of the developing unit is positioned above. Support the development unit directly. Since the second positioning member is provided at the bottom of the developing unit, the second positioning member of the lowermost developing unit is directly positioned on the bottom surface of the storage unit, and the other developing units are positioned in the developing unit. What is necessary is just to laminate | stack sequentially on. Since the abutting portion is formed of a flat surface extending in the same direction as the developing unit storage direction, the second positioning member provided on the bottom portion can be more reliably supported, and the developing unit is stored. When doing so, the second positioning member can be accommodated along the contact portion. When the developing unit located below is removed, the developing unit can be temporarily supported by the auxiliary member coming into contact with the storage portion. Therefore, the developing unit can be reduced in size and the developing unit can be prevented from being bent.

  The image forming apparatus according to claim 2, wherein the first positioning member in the image forming apparatus according to claim 1 restricts movement in a storage direction in which the developing unit is stored, and the second positioning member is the developing unit. Positioning in the height direction is performed.

  According to such a configuration, since the positioning is performed with respect to the storing direction and the height direction of the developing unit, it is possible to perform the positioning stably while preventing the developing unit from being bent.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, wherein the front of the abutting portion in the storage direction stored in the storage portion is inclined downward. It is characterized by.

  Since the front of the contact portion in the storage direction is inclined downward, the developing unit can be easily moved back and forth.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, wherein the contact portion and the second positioning member are formed of the same member. It is characterized by being.

  Since the contact portion and the positioning member are formed of the same member, errors due to the manufacturing process are reduced, and positioning is more accurate. The image forming apparatus according to claim 5 is the image forming apparatus according to any one of claims 1 to 4, wherein the second positioning member of the developing unit separated from the developer carrier. It is provided at the rear end. Since the second positioning member is provided at the rear end of the developing unit, the developing unit can be stably positioned at a separated position while preventing the developing unit from being bent.

  An image forming apparatus according to a sixth aspect is the image forming apparatus according to any one of the first to fifth aspects, wherein the second positioning member is a roller.

  Since the second positioning member is a roller, the developing unit can be easily moved.

  An image forming apparatus according to a seventh aspect is the image forming apparatus according to any one of the first to sixth aspects, wherein the second positioning member passes through the center of gravity of the developing unit and is disposed on both sides. It is located on the line orthogonal to the straight line which connects each provided said 1st positioning member, It is characterized by the above-mentioned.

  Since the second positioning member is positioned on a line passing through the center of gravity of the developing unit and perpendicular to the straight line connecting the first positioning members provided on both sides, the developing unit is positioned with stable three-point support. be able to.

  The image forming apparatus according to claim 8 is the image forming apparatus according to any one of claims 1 to 6, wherein a developer carrying member is rotated on one end side of the developing unit, and the developer is rotated. When the carrier is rotated, the driving unit further includes a driving unit that applies a load downward to the developing unit, and the second positioning member is provided closer to the driving unit than the center of the length in the width direction of the developing unit. It is characterized by being.

  When the developing unit has a driving unit that applies a load to the lower side, the developer carrier rotates so that the moment received by the developing unit is greater on the side having the driving unit than on the side having no driving unit. Become. Therefore, by providing a roller on the drive unit side so that the balance of the load applied to the developing unit is balanced, the load applied to one end of the developing unit and the load applied to the other end are balanced, and the developing unit can be supported stably.

  The image forming apparatus according to claim 9, wherein the first positioning member is both ends of a shaft that rotatably supports the developing carrier. The image forming apparatus described.

  Since both end portions of the shaft of the development carrier are directly used as the first positioning members, positioning can be performed with a simple configuration.

  An image forming apparatus according to a tenth aspect is the image forming apparatus according to any one of the first to ninth aspects, wherein the developing unit has a distance between the top portion and the bottom portion in the developing unit. The storage direction is different between the rear and the front.

  Since the distance between the top and bottom of the developing unit is different between the front and rear in the storing direction, when the developing units are stacked and stored, it is easy to store them between the developing units.

  An image forming apparatus according to an eleventh aspect is the image forming apparatus according to any one of the first to tenth aspects, wherein cyan (C), magenta (M), yellow (Y), and black (K). This is a four-cycle color laser printer in which development units containing the four color developers are arranged in parallel.

Embodiments of the present invention will be described with reference to FIGS. [Configuration of image forming apparatus]
First, an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a side sectional view of the image forming apparatus 1.

As shown in FIG. 1, the image forming apparatus 1 is provided with a paper feeding unit 3 in the lower part of the main body case 2 and an image forming unit 4 in the center.

  On the rear side of the main body case 2 (the right side in FIG. 1 is the front side and the left side is the rear side, the same applies hereinafter), a lid 21 that rotates about the hinge pin 21a is provided.

  Further, at the upper part of the main body case 2, a paper discharge port 22 for discharging the paper P on which a desired image is formed by the image forming unit 4 is provided.

  The paper feed unit 3 is located below the image forming apparatus 1 and includes a paper storage unit 31 and a paper feed roller 32.

  The paper storage unit 31 has a rectangular shape and is provided with a space for storing a plurality of sheets of paper P that are printing media. A handle 36 is provided on the front side (right side in FIG. 1) of the main body case 2. The user pulls the handle 36 in the horizontal direction, pulls out the paper storage unit 31, and sets a plurality of papers P so that the printing surface is on the upper side.

  The paper feed roller 32 is rotatably supported so as to abut on the front side (left side in FIG. 1) of the uppermost paper P among the papers P stored in the paper storage unit 31. As the paper feed roller 32 rotates clockwise, the uppermost paper P stored in the paper storage unit 31 is conveyed in the direction of arrow X.

  The image forming unit 4 includes a developing unit 11, a photosensitive unit 12, an intermediate transfer unit (transfer unit) 13, and a fixing unit 14.

  The developing unit 11 is provided on the front side (the right side in FIG. 1) inside the main body case 2. The developing unit 11 is provided with a storage unit 41 for storing a developing unit 46 including toner (developer) of each color.

  The developing unit 46 includes a developing unit 46C that stores cyan (C) toner 49C, a developing unit 46M that stores magenta (M) toner 49M, a developing unit 46Y that stores yellow (Y) toner 49Y, There are four types: a developing unit 46K containing black (K) toner 49K. Then, the developing unit 46M, the developing unit 46C on the developing unit 46M, and the developing unit 46K on the developing unit 46C are sequentially stacked and stored in the storage unit 41. Detailed configurations of the developing unit 46 and the storage unit 41 will be described later.

  As shown in FIG. 1, the photosensitive portion 12 is provided at the center inside the main body case 2 and includes a photosensitive belt (image carrier) 61, a laser scanner 62, a charger 63, and a cleaning unit 64.

  The photosensitive belt 61 is supported by rotating rollers 61a, 61b, and 61c. The photosensitive belt 61 can abut on an intermediate transfer belt 71 and four developing rollers (developer carrying members) 48 described later.

  A charger 63 is disposed below the main body case 2. The charger 63 faces the photoconductor belt 61 and charges the photoconductor belt 61.

The laser scanner 62 is provided below the storage unit 41. The laser scanner 62 is a well-known one formed by a laser beam generator, a polygon mirror, a lens, a reflection mirror, and the like (not shown). Laser light 6 based on image data generated by the laser light generator
2a is passed or reflected through a polygon mirror, a lens, and a reflection mirror. The laser beam 62a that has passed or reflected is irradiated onto the photosensitive belt 61 charged by the charger 63 at a high speed operation to form a charge pattern based on the image data.

  The cleaning unit 64 is provided on the opposite side of the charger 63 from the position where the laser scanner 62 is disposed (left side of the charger 63 in FIG. 1), and removes transfer residual toner from the photoreceptor belt 61.

  As shown in FIG. 1, the intermediate transfer unit 13 is provided between the photosensitive unit 12 and the fixing unit 14, and includes an intermediate transfer belt 71, intermediate transfer belt rollers 72 to 74, and a transfer roller 75. ing.

  A first intermediate transfer belt roller 72 is disposed at a position facing the photosensitive belt 61, and a second intermediate transfer belt roller 73 is disposed at a position facing the transfer roller 75. The intermediate transfer belt 71 is an intermediate transfer belt 71. The rollers 72 to 74 are supported at three points.

  The intermediate transfer belt 71 is rotated by the intermediate transfer belt rollers 72 to 74, contacts the photosensitive belt 61 at a position supported by the first intermediate transfer belt roller 72, and each color toner 49 formed on the photosensitive belt 61. Is transferred to the intermediate transfer belt 71. When all color toners are transferred to the intermediate transfer belt 71, the paper P is conveyed by the paper feed roller 32. When the paper P passes between the transfer roller 75 and the second intermediate transfer belt roller 73, the toner on the surface of the intermediate transfer belt 71 is transferred to the paper P. Thereafter, the paper P on which the toner 49 is transferred is conveyed to the fixing unit 14.

  The fixing unit 14 is provided on the rear side of the main body case 2 and above the transfer roller 75 and includes a pair of fixing rollers 81 and 82 facing each other. When the paper P passes between the fixing rollers 81 and 82, the fixing rollers 81 and 82 pressurize and heat the toner 49 transferred to the paper P to fix the toner 49.

  A paper discharge port 22 is provided above the fixing unit 14, and a pair of transport rollers 86 are provided near the paper discharge port 22. The paper P fixed by the fixing unit 14 is sent to the paper discharge port 22 through the pair of transport rollers 86.

  Next, the configuration of the developing unit 46 and the storage unit 41 will be described in further detail with reference to FIGS.

  2A is a perspective view when the top plate 47a of the developing unit 46 is up, FIG. 2B is a perspective view when the bottom plate 47b of the developing unit 46 is up, and FIG. 4 is a partial side view when the unit 46 is accommodated in the image forming apparatus 1, FIG. 4 is a partial top view when the developing unit 46 is accommodated in the image forming apparatus 1, and FIG. FIG. 6 is a partial rear view when the developing unit 46 is stored.

  As shown in FIG. 1, the developing unit 46 includes a developing roller 48, a toner 49, a supply roller 50, and the like inside a synthetic resin unit case 47.

The supply roller 50 is provided behind the developing roller 48 (on the right side in FIG. 1) and adjacent to the developing roller 48, and supplies the toner 49 to the developing roller 48. The developing roller 48 is supported by the developing roller shaft 51, and both end portions 51a of the developing roller shaft 51 protrude from both side surfaces 47c of the developing unit 46 (see FIGS. 3 and 4). The projecting end portions 51a of the developing roller shaft serve as a first positioning member. The surface of the developing roller 48 is coated with a conductive rubber material, and the toner has an electric charge, so that it adheres to the surface of the developing roller 48.

  As shown in FIG. 2, a driven portion 56a for driving the developing roller 48 is provided at one end of the developing unit 48 (on the right side in FIG. 2). The driven portion 56a meshes with a driving portion 56b provided in the image forming apparatus 1, and rotates in the arrow direction when the driving portion 56b is driven. The toner 49 adheres to a predetermined position of the photosensitive belt 61 as the developing roller 48 rotates.

  As shown in FIG. 2, the unit case 47 is integrally formed with a bottom 47b, left and right side surfaces (a pair of side portions) 47c, and a back surface 47d.

  The bottom 47b is formed in a shape in which a plurality of (three in this embodiment) arcs are continuous so that the toner can be stirred uniformly. Further, the front is rounded along the supply roller 50, and the front is further inclined upward (see FIG. 2B). The back surface 47d has a rectangular shape and extends upward vertically from the rear side of the bottom 47b. Side surfaces 47c are respectively provided continuously to the sides of the bottom 47b and the back surface 47d. The height h0 of the side surface 47c is longer than the sum of the height h1 of the back surface 47d and the thickness h2 of the top plate 47a described later. Since the back surface 47d and the side surface 47c are continuous with the bottom portion 47b, the side surface 47c protrudes upward from the back surface 47d. The upper surface of the protruding portion serves as an abutting portion 53 that abuts on a roller 52 described later. Further, the front side of the side surface 47c is inclined downward, and except for this inclined portion, the abutting portion 53 has a flat surface continuing to the front while maintaining a certain width.

  The top plate 47 a covers the upper part of the unit case 47 excluding the contact part 53. As shown in FIG. 3, an inclined portion 55 is formed on the front side of the developing unit 46 of the top plate 47a (left side in FIG. 3) so as to incline downward. The front of the bottom 47b is also inclined upward, and the distance between the top plate 47a and the bottom plate 47b is smaller at the front than at the rear. By having the inclined portion 55, when the developing unit 46 is accommodated in the accommodating portion 41, the developing unit to be accommodated between the two developing units 46 or between the developing unit 46 and the bottom surface 41a of the accommodating portion 41 is provided. 46 can easily enter. Here, the top is the top surface of the developing unit 46 (top plate 47a and contact portion 53).

  As shown in FIG. 2B, a bearing 57 is provided at the rear end of the bottom 47b so as to protrude below the bottom 47b. This bearing 57 has a groove 57a cut out so that the roller 52 can be attached from below. Each roller 52 has a shaft 52a protruding from the center of the disk. The roller 52 is attached by fitting the shaft 52a of the roller 52 into the groove 57a.

  The roller 52 contacts the contact portion 53 when the developing unit 46 is stored in the storage portion 41 (see FIG. 3). When the developing unit 46 is moved back and forth, the roller 52 is moved by rotating on the contact portion 53.

  As shown in FIG. 2, both end portions 51 a of the developing roller shaft 51 protrude in front of the side surface 47 c of the unit case 47, and insertion auxiliary protrusions 54 having the same shape on the left and right are provided on the rear side thereof.

  On the other hand, as shown in FIGS. 3 and 4, guide grooves 42 are provided on the left and right inner surfaces of the storage portion 41. By inserting the both end portions 51 a of the developing roller shaft 51 and the insertion auxiliary projection 54 according to the guide groove 42, the developing unit is guided so as to be stored in a predetermined position of the storage portion 41.

  The guide groove 42 is provided with a notch 42a at the end (see FIG. 3). By providing the notch 42a, the developing roller shaft 51 and the insertion assisting protrusion 54 are easily inserted into the guide groove 42 when the developing unit 46 is stored.

  Further, as shown in FIG. 4, a stopper 43 and a spring 44 are provided in the back of the storage portion 41. On the other hand, as shown in FIG. 1, the lid 21 is provided with a cam 26. After the developing unit 46 is stored in the guide groove 42, the lid 21 is closed and the cam 26 is rotated to move the developing unit 46 to a predetermined position against the urging force of the spring 44 (FIG. 4 ( a)). The spring 44 gives a force to push the developing roller shaft 51 back to the lid 21 side.

  Except for the time of image formation, the developing roller 48 and the photosensitive belt 61 provided in the photosensitive portion 12 are not in contact with each other (see FIG. 4B).

  The height A of the insertion assisting protrusion 54 is configured to be smaller than the width B of the guide groove (see FIG. 3). When no other developing unit 46 is stored below the developing unit 46 stored in the storage unit 41 of the main body, the insertion assisting protrusion 54 comes into contact with the bottom surface of the guide groove 42, thereby temporarily developing the developing unit. 46 is supported (see FIG. 5). When another developing unit 46 is stored below the stored developing unit 46, the roller 52 of the developing unit 46 located on the upper side and the contact portion 53 of the developing unit 46 located on the lower side contact each other. Therefore, the contact portion 53 supports the developing unit 46. At that time, the insertion assisting protrusion 54 is not in contact with the guide groove 42 (see FIG. 6).

The roller 52 attached to the bearing 57 of the developing unit 46 located at the lowermost portion (the developing unit 46Y in FIG. 1) is supported by contacting the bottom surface 41a of the storage unit 41 (see FIGS. 3 and 6). Further, both end portions 51 a of the developing roller shaft 51 are always positioned by the guide groove 42. [Print Processing Method in Image Forming Apparatus]
Next, a printing processing method by the image forming apparatus 1 in the present embodiment will be described with reference to FIGS. FIG. 7 is a side sectional view of the image forming apparatus 1 when the lid 21 is opened.

  As shown in FIG. 7, the user opens the lid 21 of the main body case 2, and defines the both end portions 51 a of the developing roller shaft 51 of the developing unit 46 and the insertion auxiliary protrusion 54 for each color along the guide groove 42. Store in place. At this time, the developing roller 48 on the front surface of the developing unit 46 is not in contact with the photosensitive belt 61.

  When the developing unit 46 is already stored under the developing unit 46 or when the lowermost developing unit 46 is stored, the rollers 52 provided on the bottom plate 47b of the developing unit 46 to be stored are stored. Is rotated along a contact portion 53 provided on the top plate 47a of the developing unit 46 located below. Then, after storing the developing unit 46 at each position, the lid 21 of the main body is closed. When replacing the developing unit 46, the developing unit 46 to be replaced may be attached and detached according to the procedure described above.

  When image data is sent from an external device, the laser scanner 62 emits laser light 62a according to the sent image data.

  When the laser beam 62a is irradiated, the laser beam 62a forms a charge pattern only at a predetermined position corresponding to the image data on the photosensitive belt 61 charged by the charger 63.

On the other hand, in the developing unit 11, the cam 26 formed on the lid 21 rotates to develop the developing unit 4.
6 is pushed out to the photosensitive portion 12. FIG. 1 shows a state in which the developing unit 46C is pushed out toward the photosensitive belt 61 by the rotation of the second cam 26C from the top.

  When the developing unit 46 is pushed out, the developing roller 48 of the developing unit 46 and the photosensitive belt 61 come into contact (see FIG. 4A). The toner 49 accommodated in the developing unit 46 is uniformly attached to the surface of the developing roller 48 that comes into contact with the photosensitive belt 61, and the developing roller 48 and the photosensitive belt 61 come into contact with each other, so The toner 49 adhering to the surface adheres to a predetermined position where the charge pattern of the photosensitive belt 61 is formed.

  When the processing for one page is completed, the cam 26 rotates again. Since the spring 44 always urges the front of both ends of the developing roller shaft 51 of the developing roller 48, the developing unit 46 is pushed back again (see FIG. 4B).

  As shown in FIG. 1, the toner attached to the photosensitive belt 61 from the developing roller 48 is transferred to the intermediate transfer belt 71. Untransferred toner that has not been transferred to the intermediate transfer belt 71 is collected by the cleaning unit 64. Subsequently, toner 49 of another color is attached to the photosensitive belt 61 from the developing roller.

  By repeating this operation four times, the four color toners 49 based on the image data are transferred to the intermediate transfer belt 71, and a desired image is formed. Then, the image formed on the intermediate transfer belt 71 is transferred to the paper P passing between the transfer roller 75 and the second intermediate transfer belt roller 73.

  Thereafter, the sheet P on which the image has been transferred passes between the fixing rollers 81 and 82 of the fixing unit 14 and the desired image is fixed. Thereafter, the paper P is discharged to the outside from the paper discharge port 22 of the apparatus main body by the pair of transport rollers 86, and the printing process ends.

  As described in detail above, in the image forming apparatus 1 according to the present embodiment, when a plurality of development units 46 are stacked and stored in the storage unit 41, the front of the development unit 46 is at both ends of the development roller shaft 51. 51a contacts the stopper 43 provided in the guide groove 42, respectively. Since the center of gravity of the developing unit 46 is between the developing roller shaft 51 and the roller 52, the rear of the developing unit 46 swings with the developing roller shaft 51 as a fulcrum. On the rear side of the swinging developing unit 46, the roller 52 and the abutting portion 53 of the developing unit 46 located on the lower side or the bottom surface 41a of the storage portion 41 abut. Accordingly, the movement of the developing unit 46 in the storage direction is restricted by both end portions 51 a of the developing roller shaft 51, and the height direction is positioned by the rollers 52. That is, the position of the developing unit 46 in the storage unit 41 is defined.

  Further, the developing units 46 accommodated in a stacked manner are not positioned independently, but the lowermost developing unit (46Y in FIG. 1) is positioned by the bottom surface 41a of the storing portion 41 and the guide groove 42. Then, the developing unit (46M in FIG. 1) positioned thereon is positioned by the contact portion 53 and the guide groove 42 provided in the lowermost developing unit 46Y. Therefore, the developing unit 46 is small in size and, even after being accommodated in the accommodating part 41, the abutment part 53 of the developing unit 46 supports the roller 52 of the developing unit located above, so that the developing unit 46 is under its own weight. The developing unit 46 is prevented from being bent.

  Further, if the positioning members are two protrusions protruding outward from the left and right side surfaces, the protrusions cannot be supported at four points unless the height of each protrusion is accurate. Particularly in a wide developing unit, it is difficult to accurately align the heights of the protrusions in this way. However, in this embodiment, since the developing unit located below supports the developing unit located above, the developing unit can be supported at an accurate position.

Further, when a color printer is configured by stacking a plurality of process units in which a developing unit and a photosensitive unit are integrated, a case portion for supporting the developing unit is required for each developing unit. However, in this embodiment, since the positioning is performed by bringing the developing units 46 into direct contact with each other, the storage portion 41 is high enough to store a plurality of (in this embodiment, four) developing units. Good. Therefore, the image forming apparatus 1 can be reduced in size. [Modification]
The present invention is not limited to the above configuration, and can be modified without departing from the present invention.

  The present embodiment is a four-cycle color laser printer, but is not limited thereto, and may be applied to, for example, a tandem color laser printer in which a photosensitive drum is arranged for each developing unit.

  Further, as shown in FIG. 8B, a reinforcing portion 93 extending in the direction perpendicular to the developing roller shaft 51 is provided at the center in the width direction of the bottom portion 47b, and a second positioning member is provided at the rear end of the reinforcing portion 93. A roller 91 may be provided. In such a configuration, the developing unit is supported at three points, that is, both ends 51 a of the developing roller shaft 51 as the first positioning member and the roller 91. By supporting at three points, the trouble of adjusting the heights of the plurality of second positioning members can be saved. Further, by providing the reinforcing portion 93, the developing unit is not easily deformed even when the load of the developing unit is applied to the second positioning member. At this time, the abutting portion 92 is provided at a position where it abuts on the roller 91 of the top plate (see FIG. 8A).

  The roller 91 is disposed at the rear end of the developing unit at a position away from the developing roller shaft on an extension line passing through the center of gravity of the developing unit and perpendicular to the developing roller shaft. Accordingly, since the developing unit in FIG. 8 is symmetrical in terms of weight, the roller 91 is provided at the center in the width direction of the developing unit.

  Moreover, the contact part 92 does not need to be comprised by the flat surface. For example, as shown to Fig.8 (a), the structure inclined toward the front may be sufficient. Since the contact portion 92 is inclined, the roller 91 rotates and moves along the inclination of the contact portion 92 during image formation.

  Further, as shown in FIG. 9, the roller 93 as the second positioning member may be provided on the driven unit 56 side from the center of the developing unit.

  As described above, when the driven unit 56a is provided at one end of the developing unit, the moment that the developing unit receives due to the driven unit 56a rotating in the arrow direction is the side on which the driven unit 56 is provided. Is higher than the other side (left side in FIG. 9). Therefore, it is preferable to provide the roller 93 at an optimal position where the balance of the load applied to the developing unit is balanced.

  Note that the second positioning member may not be a roller. For example, the protrusion may be a simple protrusion, or a surface may be contacted instead of the protrusion.

  In the present embodiment, the second positioning member is provided on the bottom 47b of the unit case 47 of the developing unit 46, and the contact portion is provided on the top, but as shown in FIG. 10, a roller 96 is provided on the top. A contact portion 97 may be provided on the bottom plate 47b. In such a configuration, the roller 96 provided on the top plate of the developing unit receives the contact portion 97 provided on the bottom plate 47b of another developing unit located above the developing unit. By providing a protrusion 98 such as a roller with which the bottom plate of the developing unit housed in the lowermost part comes in contact with the bottom surface of the housing part that houses the developing unit, the entire plurality of developing units can be positioned accurately.

  In the present embodiment, the contact portion is provided in a shape protruding from the top portion. However, as shown in FIG. 11, the contact portion may be a groove 99 extending from the rear to the front. At this time, the developing unit moves as the second positioning member passes through the groove 99.

  The first positioning member directly uses the developing roller shaft 51. However, for example, a protrusion that supports the developing roller shaft may be provided on the side surface, and the protrusion may be used as the first positioning member. With the first positioning member as a fulcrum, the rear of the developing unit is supported by its own weight on the bottom surface 41a of the storage unit 41 or the contact portion 53 of the developing unit 46 located below. That is, the center of gravity of the developing unit is between the first positioning member and the roller that is the second positioning member, the first positioning member is on the developing roller side, and the second positioning member is on the side opposite to the first positioning member. Is provided. Therefore, the first positioning member needs to be provided at a position close to the developing roller 48, specifically, in front of the middle of the developing unit. The roller is provided at a position further away from the developing roller than the first positioning member, specifically, at the rear side from the middle of the developing unit. In particular, as in the present embodiment, the first positioning member is provided at both ends of the developing roller shaft, and a roller is provided at the rear end of the developing unit farthest from the first positioning member, whereby positioning can be performed more stably. Further, the first positioning member does not have to be a protrusion, and it is sufficient if the developing unit can be supported from both ends of the developing roller at a position corresponding to the developing roller. For example, if the first positioning member has a concave shape on the side surface and can support the developing unit at a position corresponding to the developing roller, such as a supporting base provided in front of the storage unit, the concave portion is supported. Good. By providing the first positioning member at a corresponding position of the developing roller, it can be supported at an accurate position of the developing roller, and when the toner is attached to the photosensitive belt from the developing roller, the toner is uniformly attached. Can do.

  In addition, when the second positioning member is provided at two places in the width direction both ends of the developing unit, the first positioning member, the second positioning member, and the contact surface are provided on the side surfaces, respectively. can do. Thus, by comprising with the same member, the error for every member becomes small and positioning becomes accurate.

  In this embodiment, the front of the developing unit 46 is inclined, but the same effect can be obtained even if the rear of the developing unit is inclined.

1 is a side sectional view of an image forming apparatus according to an embodiment. It is a perspective view of the developing unit in the present embodiment. FIG. 3 is a partial side view when the developing unit in the present embodiment is housed in the image forming apparatus. FIG. 3 is a partial top view when the developing unit in the present embodiment is housed in the image forming apparatus. FIG. 4 is a partial rear view when the developing unit in the present embodiment is housed in the image forming apparatus. It is a rear view when all the developing units in this embodiment are stored. FIG. 3 is a side cross-sectional view of the image forming apparatus when a lid is opened in the present embodiment. It is a perspective view of the development unit in other embodiments. It is a perspective view of the development unit in other embodiments. FIG. 10 is a partial side view when a developing unit according to another embodiment is housed in an image forming apparatus. It is a perspective view of the development unit in other embodiments.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body case 3 Paper feed part 11 Developing part 14 Fixing part 41 Storage part 42 Guide groove 46 Developing unit 47 Unit case 48 Developing roller (developer carrier)
49 Toner (Developer)
51 Developing roller shaft 51a Both ends (first positioning member)
52, 93, 96 Roller (second positioning member)
53, 92, 94, 97, 99 Contact part 56a Driven part 56b Drive part 61 Photosensitive belt (image carrier)
P paper (medium to be printed)

Claims (11)

A developing unit having at least a developer and a developer carrying member, and having a pair of side portions that rotatably support the developer carrying member, a top portion, and a bottom portion facing the top portion is provided in a horizontal direction. In an image forming apparatus in which a plurality of layers are stacked in a detachable storage unit, and an image is formed on a print medium via the developer carrier, the image carrier, a transfer unit, and a fixing unit.
The developing unit is
A first positioning member that is provided on both side portions and positions the developing unit by contacting the storage portion;
A second positioning member that is provided at the bottom and positions the developing unit by contacting a developing unit positioned below the plurality of stacked developing units;
A flat surface extending in the same direction as the storage direction stored in the storage portion in the top portion, and a contact portion slidable in contact with the second positioning member when the development unit is attached or detached;
An auxiliary member that can come into contact with the storage unit when another development unit located under the development unit is removed from the storage unit;
The first positioning member is located closer to the developing carrier than the second positioning member, and has a center of gravity of the developing unit between the first positioning member and the second positioning member. Forming equipment.   The first positioning member restricts movement in a storage direction in which the developing unit is stored, and the second positioning member performs positioning with respect to a height direction of the developing unit. The image forming apparatus described.   3. The image forming apparatus according to claim 1, wherein the abutting portion is inclined in a downward direction in a storage direction in which the contact portion is stored in the storage portion.   The image forming apparatus according to claim 1, wherein the contact portion and the second positioning member are formed of the same member.   5. The image forming apparatus according to claim 1, wherein the second positioning member is provided at a rear end of the developing unit separated from the developer carrying member.   The image forming apparatus according to claim 1, wherein the second positioning member is a roller.   The second positioning member is located on a line passing through the center of gravity of the developing unit and perpendicular to a straight line connecting the first positioning members provided on both side portions. The image forming apparatus according to claim 1. On one end side of the developing unit, the developer carrying body is rotated, and when the developer carrying body is rotated, the driving unit further applies a load downward to the developing unit,
The image forming apparatus according to claim 1, wherein the second positioning member is provided closer to the driving unit than a center of a length in the width direction of the developing unit.   9. The image forming apparatus according to claim 1, wherein the first positioning member is at both ends of a shaft that rotatably supports the developing carrier. 10.   10. The image forming apparatus according to claim 1, wherein a distance between the top portion and the bottom portion of the developing unit is different between a rear side and a front side in a storage direction. . 4. A four-cycle color laser printer in which development units containing developer of four colors of cyan (C), magenta (M), yellow (Y), and black (K) are arranged in parallel. the image forming equipment according to any one of 1 to 10.

Images