JP2014153689A - Process cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge which is capable of obtaining a stable image density by reducing the change of a development gap, even when a developer carrier is in non-contact with an image carrier.SOLUTION: The process cartridge includes the developer carrier, the image carrier, a storage case storing the developer carrier and the image carrier, and a positioning member 16 attached to the side plate 11A of the storage case and supporting the developer carrier and the image carrier at a predetermined interval. The positioning member 16 and the side plate 11A are in contact with each other in the same plane. The positioning member 16 includes bearings 28 and 29 freely rotatably supporting each of the developer carrier and the image carrier and having one side end surfaces 28A and 29A being in contact with the side plate 11A. One side end surfaces 28A and 29A of the bearings 28 and 29 are located in the same plane as a contact surface C where the positioning member 16 and the side plate 11A are in contact with each other.

Description

  The present invention relates to a process cartridge in which a developer, a developer carrier, an image carrier, and the like are integrated as a unit, and an image forming apparatus such as a copying machine, a facsimile machine, and a printer on which the process cartridge is mounted.

  In an image forming apparatus using an electrophotographic two-component development system, the distance (development gap) between a developer carrier and an image carrier is a force (development capability) that causes the developer (toner) to adhere to the image carrier. ) Is greatly affected. Therefore, in order to obtain a uniform image density, it is necessary to reduce the change in the development gap.

  Conventionally, it has been proposed to improve the accuracy of the development gap by separating the function for positioning the development gap into separate members and tightening the dimensional accuracy of the separate members (see, for example, Patent Document 1). .

  It has also been proposed to improve the accuracy of the development gap by abutting a spacer, which is a part of the developer carrier, on the image carrier (see, for example, Patent Document 2).

  However, the prior art has a problem in that the dimensional variation in manufacturing the positioning member greatly affects the development gap. Further, when the spacer of the developer carrier is abutted against the image carrier, there is also a problem that the development gap changes due to wear between the image carrier and the spacer.

  An object of the present invention is to provide a process cartridge capable of obtaining a stable image density while suppressing a change in the development gap even when the developer carrying member and the image carrying member are not in contact with each other, and an image equipped with the process cartridge. It is to provide a forming apparatus.

  In order to solve the above-described problems, the present invention provides a developer carrier that carries a developer, an image carrier that forms an image by carrying a developer supplied from the developer carrier, and the developer. A carrier, a storage case for storing the image carrier, and attached to the storage case to support each of the developer carrier and the image carrier; and between the developer carrier and the image carrier. A positioning member for maintaining a constant spacing, wherein the positioning member and the storage case are in contact with each other in the same plane, and the positioning member includes the developer carrier and the image. A bearing portion that rotatably supports each of the carriers and whose one side end surface is in contact with the storage case is provided, and one side end surface of each of the bearing portions is the same as a contact surface that contacts the positioning member and the storage case Plane Characterized in that it located.

  According to the present invention, the one end surfaces of the bearing portions on the developer carrier side and the image carrier side are located in the same plane as the contact surface where the positioning member and the storage case are in contact with each other. Even if there is, it is possible to absorb the dimensional variation. As a result, it is possible to suppress the displacement of the developer carrier and the image carrier as much as possible, and a stable image density can be obtained.

It is a perspective view which shows the near side edge part of a process cartridge. Embodiment 1 is shown, (A) is a sectional view of a positioning member and a storage case before tightening a screw, and (B) is a sectional view of the positioning member and a storage case after tightening a screw. The prior art example is shown, (A) is sectional drawing of the positioning member and storage case before tightening a screw, (B) is sectional drawing of the positioning member and storage case after tightening a screw. It is the figure which showed the effect by Example 1 compared with the prior art example. FIG. 2 is a schematic configuration diagram of an image forming apparatus in which a process cartridge according to the first embodiment is mounted according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

Example 1
FIG. 1 is a perspective view showing the front end portion of the process cartridge 10, and the process cartridge 10 is pulled out in the direction of arrow A. FIG. The process cartridge 10 is mounted on an image forming apparatus such as a copying machine, a facsimile, or a printer.

  The process cartridge 10 has a storage case 11, in which a roller-shaped developer carrier 12 and a roller-shaped image carrier 13 are respectively stored. The developer carrier 12 carries toner (developer) on its outer peripheral surface. The image carrier 13 carries the toner supplied from the developer carrier 12 on its outer peripheral surface, and forms a toner image on the outer peripheral surface.

  In this embodiment, a two-component developing system is used as the process cartridge 10, and the developer carrier 12 and the image carrier 13 are not in contact (that is, the outer peripheral surface of the developer carrier 12 and the image carrier 13). In this state, there is a gap between the outer peripheral surface of the first and second outer surfaces.

  The storage case 11 is provided with a side plate 11A on the front side surface, and openings 14 and 15 are formed in the side plate 11A, respectively. A support shaft 12A provided at an end portion (front end portion) of the developer carrier 12 is passed through the opening portion 14, and an end portion (near side portion) of the image carrier 13 is passed through the opening portion 15. A support shaft (not shown) provided at the end portion is passed. In FIG. 1, when viewed from the direction of arrow B, the developer carrier 12 is disposed on the left side and the image carrier 13 is disposed on the right side.

  A plate-like positioning member 16 for positioning the developer carrier 12 and the image carrier 13 is provided outside the side plate 11A of the storage case 11. Through holes 17 and 18 are formed in the positioning member 16 in accordance with the support shaft 12A of the developer carrier 12 and the support shaft (not shown) of the image carrier 13 respectively. Further, in the positioning member 16, a screw through hole 19 is formed on the left side of the through hole 17, a screw through hole 20 is formed between the through hole 17 and the through hole 18, and a screw through hole 21 is formed on the right side of the through hole 18. Has been. The positioning member 16 is made of a molded resin.

  On the other hand, screw holes 22, 23, and 24 are formed in the side plate 11 </ b> A of the storage case 11 in accordance with the screw through holes 19, 20, and 21 of the positioning member 16. When viewed from the direction of the arrow B, the screw hole 22 is formed on the left side of the opening 14, the screw hole 23 is formed between the opening 14 and the opening 15, and the screw hole 24 is formed on the right side of the opening 15. The screw hole 22 is disposed opposite to the screw through hole 19, the screw hole 23 is disposed opposite to the screw through hole 20, and the screw hole 24 is disposed opposite to the screw through hole 21.

  Then, the screws 25, 26, and 27 are prepared, and the screw 25 is passed through the screw through hole 19 to the screw hole 22, the screw 26 is passed through the screw through hole 20 to the screw hole 23, and the screw 27 is passed through the screw through hole 21. Each is inserted into the screw hole 24. Thereafter, the positioning member 16 can be firmly attached to the side plate 11 </ b> A of the storage case 11 by tightening each of the screws 25, 26, and 27.

  At this time, the support shaft 12A of the developer carrier 12 is fitted into the through hole 17 of the positioning member 16, and the support shaft (not shown) of the image carrier 13 is fitted to the through hole 18 of the positioning member 16. As a result, the developer carrier 12 and the image carrier 13 are positioned so that their outer surfaces are slightly separated from each other.

  FIG. 2 shows a cross section of the positioning member 16 on the surface including the through holes 17, 18 and the screw through holes 19, 20, 21 and the side plate 11A on the surface including the openings 14, 15 and the screw holes 22, 23, 24. FIG. As shown in FIG. 2, the positioning member 16 is provided with bearings 28 and 29 as bearing portions so as to match the through holes 17 and 18. That is, the length of the through holes 17 and 18 (the length along the axial direction of the hole) is set shorter than the length of the screw through holes 19, 20, and 21 (the length along the axial direction of the hole). ing. And the bearings 28 and 29 are each embedded below the through-holes 17 and 18 (side which has a contact surface with the side plate 11A). A support shaft 12A of the developer carrier 12 is fitted to the bearing 28, and the developer carrier 12 is rotatably supported by the bearing 28. Further, a support shaft (not shown) of the image carrier 13 is fitted to the bearing 29, and the image carrier 13 is rotatably supported by the bearing 29.

  In this embodiment, the bearing 28 of the developer carrier 12 and the bearing 29 of the image carrier 13 have one side end surfaces (lower end surfaces) 28A and 29A that are in contact with the positioning member 16 and the side plate 11A. It is arrange | positioned so that it may be located in the same plane. That is, a contact surface C that is in contact with the side plate 11A of the storage case 11 is formed in the vicinity of the screw through-holes 19, 20, 21 of the positioning member 16, but the lower end surfaces of the bearings 28 and 29 are contact surfaces C. It is arranged to match the position of. The contact surface C is flat.

  Next, the operation of the present embodiment will be described with reference to FIGS.

  FIG. 3A is a cross-sectional view showing the main part of the conventional process cartridge (configuration of the side plate 11A of the storage case 11 and the positioning member 16 attached in contact therewith) corresponding to FIG. 2A. It is. In the conventional process cartridge, the side plate 11A of the storage case 11 is formed with recesses 30 and 31 in the portions where the openings 14 and 15 are formed, and the positioning member 16 is formed in the portion where the through holes 17 and 18 are formed. Convex portions 32 and 33 are formed. When the positioning member 16 is attached to the side plate 11A, the convex portions 32.33 are fitted into the concave portions 30 and 31, respectively, the support shaft 12A of the developer carrier 12 is fitted to the bearing 28, and the support shaft of the image carrier 13 is constructed. (Not shown) are fitted to the bearings 29 respectively. In addition, the depth of the recessed parts 30 and 31 is H (refer FIG. 3 (A)).

  However, in the process cartridge of FIG. 3, as shown in FIG. 3B, the length of the portion of the positioning member 16 in which the screw through hole 20 is formed has a length of the screw through hole 19 due to manufacturing dimensional variations. In some cases, the length is shorter than the portion where 21 and 21 are formed. In this case, a large gap S <b> 1 is generated between the upper surface of the side plate 11 </ b> A and the lower surface of the positioning member 16. When the screw 26 (see FIG. 1) is tightened through the screw through hole 20 in such a state, the positioning member 16 is greatly bent as indicated by a broken line P1. Therefore, the central axis L1 of the developer carrier 12 and the central axis L2 of the image carrier 13 are inclined as indicated by arrows C1 and C2, respectively. As a result, the development gap L (see FIG. 3A) indicating the distance between the central axis L1 of the developer carrier 12 and the central axis L2 of the image carrier 13 is greatly widened. The image carrier 13 is greatly displaced.

  On the other hand, in this embodiment, as shown in FIG. 2A, the bearing 28 of the developer carrier 12 and the bearing 29 of the image carrier 13 have the end surfaces of the positioning member 16 and the side plate 11A. Are arranged so as to be located in the same plane as the contact surface C that comes into contact with. Therefore, even if the positioning member 16 has dimensional variations in manufacturing, the conventional problem does not occur.

  For example, even if the length of the part in which the screw through hole 20 is formed is shorter than the part in which the screw through hole 19 or 21 is formed, there is a gap between the upper surface of the side plate 11A and the lower surface of the positioning member 16. Only a small gap S2 occurs. When the screw 26 is tightened through the screw 26 (see FIG. 1) through the screw through hole 20 in such a state, the positioning member 16 is bent slightly as shown by the broken line P2. Therefore, the central axis L1 of the developer carrier 12 and the central axis L2 of the image carrier 13 are inclined slightly as indicated by arrows D1 and D2, respectively. As a result, the development gap L (see FIG. 2A) does not widen greatly, and the developer carrier 12 and the image carrier 13 can be prevented from being greatly displaced. In this embodiment, since the recesses 30 and 31 as shown in FIG. 3 are not formed, the depth H of the recess is zero.

  FIG. 4 is a diagram showing the dimensional variation of the development gap in comparison with the present embodiment and the conventional example. As shown in FIG. 4, in this embodiment, the sensitivity of the development gap in the range of dimensional variation is smaller than that of the conventional example. Therefore, the dimensional variation of the positioning member with respect to the target development gap can be suppressed as compared with the conventional example.

  In this embodiment, one end surface 28A of the bearing 28 of the developer carrier 12 and one end surface 29A of the bearing 29 of the image carrier 13 are in contact with the contact surface C where the positioning member 16 and the side plate 11A of the storage case 11 are in contact. Located in the same plane. As a result, even if the positioning member 16 has a dimensional variation, the dimensional variation can be absorbed, and the displacement of the developer carrier 12 and the image carrier 13 can be suppressed as much as possible to obtain a stable image density. be able to.

  In FIG. 2, an example in which the portion in which the screw through hole 20 is formed is shorter than the portion in which the screw through holes 19 and 21 are formed, and the positioning member 16 is bent upwardly as indicated by a broken line P <b> 2. showed that. However, the present invention is not limited to this, and when the portion where the screw through hole 20 is formed is longer than the portion where the screw through holes 19 and 21 are formed, the positioning member 16 is deformed upwardly.

Example 2
Next, an image forming apparatus equipped with the process cartridge of Example 1 will be described. FIG. 5 shows a schematic configuration of the image forming apparatus according to the present embodiment.

  Reference numeral 50 denotes an image forming apparatus. In this image forming apparatus 50, image forming units 52, 53, 54, and 55 for each color are arranged along the traveling direction (arrow E) of the intermediate transfer belt 51. Here, each of the image forming units 52, 53, 54, and 55 includes the process cartridge of the first embodiment.

  The image forming units 52, 53, 54, and 55 are a K developing unit having black toner, a C developing unit having cyan toner, an M developing unit having magenta toner, and a Y developing unit having yellow toner.

  The image forming unit 52 includes a developing device 57 including a toner hopper that stores toner and a developing roller that forms a toner layer and supplies toner to a photosensitive drum (image carrier) 56. The image forming unit 52 includes a drum cleaner 58 that cleans the photosensitive drum 56, a charger 59 that charges the photosensitive drum 56, and an optical scanning device 60 that writes an electrostatic latent image on the photosensitive drum 56. Yes. The developing device 57 is provided with a toner supply roller (developer carrier) 57A.

  A toner hopper, a developing roller, a drum cleaner 58, a charger 59, and the like included in the image forming unit 52 are attached to a main body frame (not shown) and configured to be drawable from the main body of the image forming apparatus 50.

  The intermediate transfer belt 51 is drawn around a plurality of rollers and passes through the secondary transfer roller 61. The belt cleaner 62 removes residual toner on the intermediate transfer belt 51. The primary transfer roller 63 is disposed opposite to the photosensitive drum 56 and the like, and is disposed inside the intermediate transfer belt 51 and opposed to the photosensitive drum 56 and the like.

  The sheet 64 is pulled out from the sheet feeding device 65 by a pickup roller 66, passes through a separation roller, etc., and is contacted with the intermediate transfer belt 51 while being sandwiched between the secondary transfer roller 61 and its opposing roller 67, and an image is transferred. . Then, the paper 64 is sent to the fixing device 69 via the transport belt 68.

  The fixing device 69 includes a backup roller 70, an elastic roller 71, a heating roller 72, a fixing belt 73, and the like. The fixing belt 73 is stretched over the elastic roller 71 and the heating roller 72 and is driven by the rotation of the heating roller 72 or other rollers. The paper 64 is pressed against the elastic roller 71 by the backup roller 70.

  The heating roller 72 has heating means such as a halogen heater in a metal hollow shaft, and heats the fixing belt 73. The surface of the elastic roller 71 is formed of an elastic body such as silicon rubber, and the pressing force of the backup roller 70 makes the nip portion convex toward the elastic roller 71 and prevents the paper 64 from being wrapped around the fixing belt 73. Yes.

  In the case of forming an image, the photosensitive drum 56 is charged by the charger 59, and the photosensitive drum 56 is exposed by a laser beam corresponding to the image by the optical scanning device 60, and the potential on the photosensitive drum 56 is lowered. The exposed portion reaches the developing device 57 by the rotation of the photosensitive drum 56, the charged toner of the developing device 57 adheres to the image forming position, and a toner image is formed on the photosensitive drum 56.

  The toner image formed on the photosensitive drum 56 is transferred to the intermediate transfer belt 51 when the primary transfer roller 63 presses the intermediate transfer belt 51 against the photosensitive drum 56. The toner images on the photosensitive drums 56 of the image forming units 52, 53, 54, and 55 are similarly transferred to the intermediate transfer belt 51, thereby forming a color toner image.

  By the conveyance of the intermediate transfer belt 51, the toner image is transferred to the sheet 64 conveyed at the site of the secondary transfer roller 61. The sheet 64 on which the toner image is transferred is conveyed to a fixing device 69 by a conveying belt 68, and the toner is melted and fixed by heat and pressure to form a color image.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, each of the above embodiments is only an example of the present invention, and the present invention is not limited only to the configuration of each of the above embodiments. . Needless to say, changes in design and the like within the scope of the present invention are included in the present invention.

  For example, in the first embodiment, the case where the part where the screw through hole 19 is formed is shorter or longer than the other part has been described. However, the part where the screw through hole 19 or 21 is formed is more than the other part. The present invention can also be applied when the length is short or long.

  Moreover, in the said Example 1, although the contact surface C of the positioning member 16 and 11 A of side plates was three places, the contact surface C may be two places and may be four or more places.

  Further, the bearing portion is not limited to a general ball bearing or roller bearing, but may be a metal touch bearing.

DESCRIPTION OF SYMBOLS 10 Process cartridge 11 Storage case 11A Side plate 12 Developer carrier 13 Image carrier 14,15 Opening part 16 Positioning member 17,18 Through hole 19-21 Screw through hole 22-24 Screw hole 25-27 Screw 28, 29 Bearing ( Bearing)
28A, 29A One end face 50 Image forming apparatus 52-55 Image forming unit 56 Photosensitive drum (image carrier)
57 Developing Device 57A Toner Supply Roller (Developer Carrier)
C Contact surface L Development gap

JP-A-10-319716 JP 2006-329286 A

Claims (6)

A developer carrying member carrying the developer;
An image carrier for carrying the developer supplied from the developer carrier to form an image;
A storage case for storing the developer carrier and the image carrier;
A positioning member that is attached to the storage case and supports each of the developer carrier and the image carrier, and holds a constant distance between the developer carrier and the image carrier;
A process cartridge in which the positioning member and the storage case are in contact with each other in the same plane,
The positioning member is provided with a bearing portion that rotatably supports each of the developer carrier and the image carrier and whose one side end surface is in contact with the storage case.
The process cartridge according to claim 1, wherein one end face of each bearing portion is located in the same plane as a contact surface where the positioning member and the storage case contact.   Each bearing portion is embedded in the positioning member, and one side end surface of each bearing portion is flush with the end surface of the positioning member, and the storage case includes one side end surface of the positioning member and each bearing portion. The process cartridge according to claim 1, wherein a contact surface in contact with the surface is formed in a flat shape.   The process cartridge according to claim 1, wherein the positioning member is made of a molded resin.   The process cartridge according to claim 1, wherein the positioning member and the storage case are in contact with each other at at least two locations.   5. The positioning member according to claim 1, wherein the positioning member has a plurality of screw holes at locations corresponding to the contact surfaces, and is attached to the storage case by screws passed through the screw holes. The process cartridge according to one item.   An image forming apparatus comprising the process cartridge according to claim 1.