JP2007094092A - Image forming apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and its control method for detecting an engaging failure occurring when a process cartridge is attached to an apparatus main body and controlling to eliminate the engaging failure when the engaging failure is detected. <P>SOLUTION: The control method for the image forming apparatus which forms an image to a recording medium by being equipped with a process cartridge which is freely detachable to the image forming apparatus and provided with at least an image carrier and a developing roller, detects a connecting failure with the process cartridge (S3 to S6), and drives, when the connecting failure is detected, the developing roller to be rotated for a specified amount (S9). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic method and a control method thereof.

  A process cartridge used in a laser printer or the like includes a photosensitive drum as an image carrier, a charging roller as a charging member, a developing roller as a developing member, and the like. A charging member and a developing roller are brought into contact with the photosensitive drum, and a coupling member that can be positioned at a position away from the photosensitive drum is provided.

  When the process cartridge is mounted, if it is not mounted properly, the tooth contact occurs between the gears that transmit the rotation from the drive motor of the apparatus main body to the photosensitive drum and each roller. When such tooth contact occurs, the process cartridge cannot be inserted into a predetermined position. In this state, when the cover of the apparatus main body is closed and the power is turned on, the apparatus starts initial rotation. However, since the gears are misaligned due to the contact with the tooth tips, they do not mesh and the photosensitive drum does not rotate even if the drive motor of the apparatus main body is rotated. Further, since the rotation of the developing roller is performed only when the image is formed, the initial rotation ends without the state of contact with the teeth being eliminated. When such a phenomenon occurs, the contacting conveyor belt rotates while the photosensitive drum is stopped, so that rubbing marks and scratches are generated at the contact portion between the surface of the photosensitive drum and the conveying belt. When such rubbing marks are generated, the potential of the portion where the rubbing marks are generated fluctuates during image formation, causing a problem called a rubbing memory in which horizontal stripes of one rotation pitch of the photosensitive drum appear on the image. .

In order to solve such a problem, Patent Document 1 discloses a configuration in which the bar pressing member aligns the gears in a predetermined phase before the cartridge unit is completely mounted, so that the tooth contact does not occur. The technology to make is described.
Japanese Patent Laid-Open No. 6-258884

  However, the conventional example requires a mechanism for performing phase alignment between gears, which is disadvantageous in terms of downsizing and cost reduction of the apparatus.

  An object of the present invention is to solve the above-mentioned conventional problems.

  A feature of the present invention is that an image forming apparatus that detects an engagement failure that occurs when a process cartridge is mounted on the apparatus main body, and that controls the engagement failure when the engagement failure is detected, and its control. It is to provide a method.

In order to achieve the above object, an image forming apparatus according to an aspect of the present invention has the following configuration. That is,
An image forming apparatus that is detachably attached to an image forming apparatus and that mounts a cartridge including at least an image carrier and a developing roller to form an image on a recording medium,
Detecting means for detecting poor connection with the cartridge;
And developing driving means for rotating the developing roller by a predetermined amount when the connection failure is detected by the detecting means.

In order to achieve the above object, a method for controlling an image forming apparatus according to an aspect of the present invention includes the following steps. That is,
A control method for an image forming apparatus, which is detachable from an image forming apparatus and mounts a cartridge including at least an image carrier and a developing roller to form an image on a recording medium,
A detection step of detecting a connection failure with the cartridge;
A development driving step of rotating the developing roller by a predetermined amount when the poor connection is detected in the detection step.

  According to the present invention, when an engagement failure occurring when the process cartridge is mounted on the apparatus main body is detected and the engagement failure is detected, the engagement failure can be eliminated.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are essential to the solution means of the present invention. Not exclusively.

  First, the overall configuration of the color image forming apparatus according to the present embodiment will be described.

  FIG. 1 is a diagram illustrating the overall configuration of a laser printer 100 which is an aspect of a color image forming apparatus according to an embodiment of the present invention.

  The color laser printer includes an image carrier 1 (photosensitive drums 1a to 1a) that rotates at a constant speed for each color of Y (yellow), M (magenta), C (cyan), and Bk (black) in order from the lower side of FIG. 1d) and an image forming unit having a color developing device 4 (4a to 4d). The transport belt 11 sequentially transports the transfer material S fed from the feeding unit to the image forming unit in order to sequentially transfer the toner images developed in these image forming units onto the transfer material S. The transfer material S onto which the toner image has been transferred is conveyed to the fixing unit 20 where the color image is fixed on the transfer material S. The transfer material S on which the toner image is fixed in this manner is discharged to the discharge unit 24 on the upper surface of the apparatus by the rotation of the discharge roller 23. Each of the process cartridges 7 (7a to 7d) including these four color developing devices is configured to be detachable from the printer main body.

  Next, the operation of the parts related to the present embodiment will be sequentially described in detail for the configuration of each part of the color laser printer 100.

  In each process cartridge 7, the image carrier (photosensitive drum) 1 is integrally formed with the container of the developing device 4 and is detachably supported with respect to the printer main body 100. Units can be replaced independently. An image carrier (photosensitive drum) 1 according to the present embodiment is configured by applying an organic photoconductor layer to the outside of an aluminum cylinder, and is rotatably supported by a container of the photosensitive drum 1. Further, by transmitting a driving force of a driving motor (not shown) to one end of the photosensitive drum 1, the photosensitive drum 1 is rotated counterclockwise in FIG. 1 according to an image forming operation. Further, the driving force branched from the driving motor is transmitted to the developing rollers (40a to 40d) in the developing device, and the developing roller is rotated at a predetermined peripheral speed.

  The intermediate transport belt 11 is synchronized with the outer peripheral speed of the photosensitive drum 1 in order to multiplex-transfer the toner image on the photosensitive drum 1 visualized by each developing device 4 onto the transfer material S during the color image forming operation. To rotate clockwise. The transfer material S transported from the paper feed cassette 17 is electrostatically held on the intermediate transport belt 11 and sequentially transported to the transfer sections for each color. The toner image formed on each photosensitive drum 1 is disposed at a position facing the photosensitive drum 1 with the intermediate conveyance belt 11 interposed therebetween, and is a transfer that is a contact point with a transfer roller 12 (12a to 12d) to which a transfer voltage is applied. Are transferred onto the transfer material S on the intermediate conveyance belt 11 by multiple transfer. The intermediate conveyor belt 11 is supported by the main body on four axes (13, 14a, 14b, 15) with the driving roller 13 as a fulcrum. By transmitting the driving force of a driving motor (not shown) to one end of the driving roller 13 at the rear of the drawing, the intermediate conveyance belt 11 is rotationally driven according to the image forming operation. Reference numerals 49a to 49d denote developing units that form toner images corresponding to the respective colors, and reference numerals 60a to 60d denote cleaning blades that remove the remaining toner corresponding to the respective colors from the surface of the photosensitive drum 1.

  Next, an operation when image formation is performed by the laser printer 100 according to the present embodiment will be described.

  First, the sheet feeding roller 18 is rotated to separate one sheet of the transfer material S in the sheet feeding cassette 17 and conveyed to the registration roller 19. On the other hand, the photosensitive drum 1 and the intermediate conveyance belt 11 rotate in a direction indicated by an arrow at a predetermined outer peripheral speed V (hereinafter referred to as a process speed).

  The photosensitive drums 1 (1a to 1d) whose surfaces are uniformly charged by the charging unit 49 (49a to 49d) are subjected to laser exposure corresponding to the images of the respective colors from the scanner unit 3 (3a to 3d). A latent image is formed. Simultaneously with the formation of the latent image, the developing roller is rotationally driven to attach toner to the latent image on the photosensitive drum 1. At this time, development is performed by applying a voltage having the same polarity as the charging polarity of the photosensitive drum 1 and substantially the same potential. At the same time, the toner image on the photosensitive drum 1 is transferred to the transfer material S on the intermediate conveyance belt 11 at the transfer position downstream of the developing unit 4. At this time, transfer is performed by applying a voltage having a characteristic opposite to that of the toner image to the transfer portion. Each scanner unit 3 (3a to 3d) includes a semiconductor laser (10a to 10d) and a polygon mirror 9 (9a to 9d) that reflects laser light emitted from the laser.

  The above steps are performed separately for each of the four color toner images and at a timing such that the leading edges of the toner images on the transfer material S coincide. In this way, a full color image can be formed by transferring the four color toner images onto the transfer material S in a multiple transfer manner.

  The transfer material S starts to be conveyed from the above-described registration roller 19 in accordance with the timing when the first color toner image reaches the transfer portion. The transfer material S to which the toner images are applied in the order of YMCBk and the full color image is transferred is peeled off from the intermediate conveyance belt 11 and conveyed to the fixing unit 20, and after toner fixing, a discharge tray via a discharge roller pair 23. 24 is discharged with the image surface facing downward.

  Next, the process cartridge 7 according to the present embodiment will be described in more detail with reference to FIGS.

  2 and 3 are a main sectional view and a perspective view of the process cartridge 7, respectively. Since the yellow, magenta, cyan, and black process cartridges 7 (7a, 7b, 7c, and 7d) all have the same configuration, only one cartridge will be described here.

  The process cartridge 7 includes an image carrier unit 50 and a developing unit 4. The image carrier unit 50 includes a drum-shaped image carrier (photosensitive drum) 1 that is an image carrier, a primary charging unit (charging roller) 2, and a cleaning unit (cleaning unit) 60. The developing unit 4 includes developing means (developing device) for developing the electrostatic latent image on the photosensitive drum 1.

  In the image carrier unit 50, the photosensitive drum 1 is rotatably attached to the cleaning frame 51 via bearings 31 (31a, 31b) (bearings) (FIG. 3). A charging roller 2 for uniformly charging the surface of the photosensitive drum 1 and a cleaning blade 60 for removing toner remaining on the photosensitive drum 1 are disposed on the periphery of the photosensitive drum 1. Further, the residual toner removed from the surface of the photosensitive drum 1 by the cleaning blade 60 is sequentially sent to a waste toner chamber 53 provided behind the cleaning frame 51 by a toner feeding mechanism 52. 2 is transmitted according to the image forming operation by transmitting the driving force of the driving motor disposed in the apparatus main body 100 on the one end side of the process cartridge 7 on the back side in FIG. Driven in the direction of arrow X (counterclockwise).

The developing unit 4 includes a developing roller 40 that contacts the photosensitive drum 1 and rotates in the direction of arrow Y (clockwise) in FIG. 2, a toner container 41 that contains toner, and a developing frame 45. The developing roller 40 is rotatably supported by the developing frame body 45 through bearing members 47 and 48. Further, on the circumference of the developing roller 40, there are a toner supply roller 43 that contacts the developing roller 40 and rotates in the arrow Z direction (clockwise) in FIG. A certain developing blade 44 is arranged. Further, in the toner container 41, a toner transport mechanism (developer stirring transport blade) 42 for stirring the stored toner and transporting it to the toner supply roller 43 is provided. The developing unit 4 is entirely swayed with respect to the photosensitive drum unit 50 by pins 55a around the support shafts 55 provided on bearing members 47 and 48 attached to both ends of the developing unit 4, respectively. It has a suspended structure that is supported movably. When the process cartridge 7 is a single unit (not attached to the apparatus main body 100), the developing unit 4 is always urged by the pressure spring 54 so that the developing roller 40 comes into contact with the photosensitive drum 1 by a rotational moment about the support shaft 55. Has been. Further, the toner container 41 of the developing unit 4 is provided with an action receiving portion for contacting and functionally connecting a separation / contact switching means (described later) of the apparatus main body 100 when the developing roller 40 is separated from the photosensitive drum 1. The rib 46 is integrally provided.
Next, an operation mechanism when the process cartridge 7 is mounted on the apparatus main body 100 will be described in detail with reference to FIGS.

  FIG. 4 is a perspective view showing the vicinity of the side plate in the apparatus main body for explaining the process cartridge mounting method according to the present embodiment. In FIG. 4, only the photosensitive drum 1 and the bearing 31 are shown for the process cartridge 7 in order to easily explain the description of the present embodiment. In practice, however, the process cartridge 7 is integrally configured with the charging roller 2, the developing unit 4, the cleaning unit 6 and the like as described above with reference to the drawings.

  As described above, in the single state of the process cartridge 7, the developing roller 40 is always in contact with the photosensitive drum 1 as shown in FIG. As shown in FIG. 4, the process cartridge 7 has a bearing 31 (on the photosensitive drum 1) along guide grooves 34 (34 a to 34 h) which are mounting means provided on the left and right side plates 32 from the direction of the arrow (the front side of the apparatus). 31a, 31b) are inserted into the apparatus main body 100 by inserting them. At this time, the transfer belt 11 is retracted together with, for example, the front cover of the apparatus main body 100 to open the insertion portion of the process cartridge 7. As shown in FIG. 6, the position of the process cartridge 7 is determined by pressing the bearing 31 against the abutting surfaces 37 and 38 of the guide groove 34.

  Here, the pressing method of the process cartridge 7 in the apparatus main body 100 is as follows.

  FIG. 5 is a partial cross-sectional view showing a positioning part for the process cartridge according to the present embodiment to the image forming apparatus. FIG. 6 is a partial cross-sectional view showing a positioning portion of the process cartridge for the image forming apparatus according to the present embodiment.

  As shown in FIG. 5, a coupling 39 is caulked on the left and right side plates 32, and the pressing member 30 is supported on the coupling 39. When the process cartridge 7 is inserted, the pressing member 30 rotates in the clockwise direction in FIG. 5 and is positioned as shown in FIG. Thus, the bearing 31 is pressed against the abutting surfaces 37 and 38 (FIG. 6) of the guide groove 34 with a force of about 1 kgf (≈9.8 N) in the direction of the arrow F. At this time, on the back side of the apparatus main body 100 in the insertion direction of the process cartridge 7, the developing roller 40 is separated from the photosensitive drum 1 against the urging force of the developing unit 4 by the pressure spring 54 (FIG. 2). A separation cam 80 (80a to 80d) (FIG. 1) is disposed. These separation cams 80 (80a, 80b, 80c, 80d) are provided in the development units 4 (4a, 4b, 4c, 4d) of the respective colors of yellow, magenta, cyan, and black as developing roller separation / contact switching means. The boss 46 (46a, 46b, 46c, 46d) (FIG. 1) is moved up and down.

  FIG. 7 is a perspective view showing a mechanism for switching the separation and contact between the photosensitive drum and the developing roller according to the present embodiment.

  In the present embodiment, the separation cam 80 (80a to 80d) is rotated by the driving means shown in FIG. 7, that is, the DC motor 90, and the boss 46 (46a to 46d) of the developing unit 4 moves up and down with this rotation. To do. Thereby, a position where the developing roller 40 abuts on the photosensitive drum 1 and a position where the developing roller 40 is separated from the photosensitive drum 1 are created.

  FIG. 9 is a cam diagram (relationship between the separation cam and the developing clutch) according to the present embodiment.

  In this embodiment, all the developing rollers 40 and the photosensitive drums 1 are in contact with the bosses 46 (46a to 46d) at the maximum radius of the separation cams 80 (80a to 80d) of all colors of yellow, magenta, cyan, and black. The separated state is a standby state ((1) in FIG. 9). Further, a state in which all the developing rollers 40 and the photosensitive drums 1 are in contact with the boss 46 at the minimum radius of the separation cams 80 (80a to 80d) of all colors of yellow, magenta, cyan, and black is in a full color state (FIG. 9). (5)). Further, a state in which the separation cams 80 (80a, 80b, 80c) of three colors of yellow, magenta, and cyan are in contact with the boss 46 at the maximum radius and the black separation cam 80d is in contact with the boss 46 at the minimum radius is a monocolor state. . In this color state, only the black developing roller 40 contacts the photosensitive drum 1 ((8) in FIG. 9). Thus, one of these three states can be selected.

  In the full color mode, the developing roller 40 contacts the photosensitive drum 1 in the order of yellow (1st) → magenta (2st) → cyan (3st) → black (4st) to perform the developing operation ((1 in FIG. 9). ) To (5)). After the completion of the developing operation, the developing roller 40 is separated from the photosensitive drum 1 in the order of yellow (1st) → magenta (2st) → cyan (3st) → black (4st), and printing is finished (FIG. 9 ( 5) to (1) state).

  That is, in the present embodiment, as shown in the cam diagram of FIG. 9, each color separation cam 80 (80a, 80b, 80c, 80d) has a profile, and each color separation cam 80 (80a, 80b). , 80c, 80d) by shifting the phase, the above-described mode switching is made possible.

  As shown in the cam diagram of FIG. 9, the states (1) to (8) exist. Each state is as follows.

  (1) is a state in which the developing roller of the developing unit for all colors and the photosensitive drum are separated.

  (2) shows a state in which the developing roller of the yellow developing unit and the photosensitive drum are in contact with each other (magenta, cyan, and black are separated).

  (3) is a state in which the developing roller of the yellow and magenta developing unit and the photosensitive drum are in contact with each other (cyan and black are in a separated state).

  (4) is a state in which the developing roller of the yellow, magenta, and cyan developing units and the photosensitive drum are in contact with each other (black is in a separated state).

  (5) is a state where the developing roller of the developing unit for all jobs and the photosensitive drum are in contact (full color mode).

  (6) shows a state in which the developing roller of the yellow developing unit is separated from the photosensitive drum (magenta, cyan, and black are in contact).

  (7) is a state in which the developing roller and the photosensitive drum of the yellow and magenta developing unit are separated (cyan and black are in a state).

  (8) is a state in which the developing roller and the photosensitive drum of the yellow, magenta, and cyan developing units are separated from each other (black is in a contact state, mono color mode).

  FIG. 1 described above shows the state (1), in which the developing rollers and the photosensitive drums of all the developing units are separated from each other. In this state, the separation cams 80a to 80d described above are in contact with the bosses 46a to 46d, and the boss 46 moves in the direction of the arrow in the drawing to separate the developing roller and the photosensitive drum.

  FIG. 17 shows the state (5), in which the developing rollers of all the developing units are in contact with the photosensitive drums.

  Further, FIG. 18 shows a state (8), in which the developing roller of the black developing unit and the photosensitive drum are in contact with each other. In this state, the bosses 46a to 46c of the yellow, cyan, and magenta developing units move in the direction of the arrow in the drawing to separate the developing roller and the photosensitive drum.

  FIG. 8 is a perspective view of the drive unit of the process cartridge according to the present embodiment.

  In the present embodiment, the unit that drives the process cartridge 7 includes a gear 71d that rotates the photosensitive drum 1 from a driving motor 70d that is a driving unit provided for each color as shown in FIG. 8, and a developing roller. 40 is branched into a series 72d for rotationally driving 40. In the present embodiment, an outer rotor motor (DC motor) is employed as the drive motor. Further, developing clutches 74d and 75d as drive switching means are provided on the driving side of the developing roller 40 so that the developing roller 40 can be rotated and stopped when the photosensitive drum 1 is rotating.

  As described above, in this embodiment, the photosensitive member driving means for driving each photosensitive drum 1 and the developing driving means for driving each developing roller 40 are a single motor common to each process cartridge. The rotational driving force from the apparatus main body 100 side is generated by the photosensitive member drive transmission means and the development drive transmission means that are functionally connected to the drive unit on the apparatus main body 100 side with the process cartridge 7 mounted on the apparatus main body 100. These are transmitted to the photosensitive drum 1 and the developing roller 40, respectively.

  FIG. 10 is a perspective view for explaining the photosensitive member drive transmission means according to the present embodiment. The parts common to those in the above-mentioned drawings are indicated by the same symbols, and their explanation is omitted.

  Here, the photosensitive member drive transmission means is a drive transmission means using a coupling. A gear 71 (71a to 71d) that rotates integrally with the coupling 76 on the apparatus main body 100 side slides in the axial direction of the photosensitive drum 1 so as to come into and out of contact with each other. The process cartridge 7 can be attached / detached by opening the cover on the front surface of the apparatus main body and simultaneously rotating the transport belt unit to the attachment / detachment position of the process cartridge 7. The separation / contact mechanism for separating / connecting the coupling 76 (76a to 76d) is interlocked with the rotation operation of the conveyor belt unit. When the process cartridge 7 is attachable / detachable, the process cartridge 7 is separated, and when the process cartridge 7 is moved to the image forming position, the coupling 76 is engaged.

  The development drive transmission unit is a drive transmission unit using gears. Gears (coupling gears) 77 (77a to 77d) on the apparatus main body side are fixed, and the gears mesh with each other when the process cartridge 7 is mounted.

  With such a drive configuration, the rotational driving of the photosensitive drums 1 for each color can be controlled independently, so that it is possible to control to reduce color misregistration that is always a problem in an inline-type full-color image forming apparatus. In addition, the rotational driving of the developing roller 40 can be stopped while the photosensitive drum 1 is rotationally driven. Naturally, it is much cheaper to provide the clutch as described above than to provide another motor for driving the developing roller 40.

  In the present embodiment, the developing clutches 74d and 75d perform connection for rotating the developing roller 40 and disconnection without rotating the developing roller 40 by rotation of the clutch gear 97d (FIG. 8). The clutch gear 97d has a cam shape in the thrust direction, and the clutch cam 73d moves in the thrust direction as the clutch gear 97d rotates. Along with this, the clutch 75d moves in the thrust direction, whereby the clutch 74d is connected and disconnected. The clutch gear 97d is connected to the gear 96d, and the gear 96d rotates with the rotation of the gear 95d via the shaft. Here, the gear 95d and the gear 96d have the same number of teeth. The gear 95d is connected to a separation gear 94d attached to the separation shaft 81d. The separation gear 94d and the clutch gear 97d have the same number of teeth, and the phase relationship between the rotation of the separation cam 80d attached to the separation shaft 81d and the clutch gear 97d is always the same. Thereby, the rotation of the separation cam 80 and the ON / OFF operation of the clutches 74 and 75 are synchronized.

  As shown in FIG. 9, as the separation cam 80 rotates the developing roller 40 from the contact position to the separation position, the development clutches 74 and 75 are shifted from the ON state to the OFF state. In this embodiment, the developing roller 40 stops rotating after the developing roller 40 is separated from the photosensitive drum 1, and the developing roller 40 contacts the photosensitive drum 1 after the developing roller 40 rotates. Further, in the state (home position) of FIG. 9 (1) (home position), the developing rollers 40 of all the colors are stopped from rotating. Further, in the state (5) (full color mode), the developing rollers 40 for all the colors rotate, and in the state (8) (mono color mode), only the black developing roller 40d rotates and the developing rollers for other colors. 40a-40c is set to be in a stopped state.

  FIG. 11 is a diagram illustrating a tooth tip contact state in the embodiment of the present invention.

  When the process cartridge 7 is mounted on the apparatus main body 100, the development drive transmission means is a drive transmission using gears, and the position of the gear 77 on the apparatus main body side is fixed. For this reason, depending on the phase of the gear, when the teeth are correctly meshed with each other, there are cases where the tooth tips come into contact with each other (FIG. 11) (FIG. 11 is necessary for explanation in order to facilitate understanding). Except for the part). When these gears are properly meshed with each other, image formation can be performed without any problem. However, as shown in FIG. 11, the process cartridge 7 cannot be inserted into a predetermined position when a tooth tip occurs, and the bearing 31 cannot be pressed against the abutting surfaces 37 and 38 of the guide groove 34.

  In this state, when the cover of the apparatus main body is closed and the power is turned on, the apparatus 100 starts initial rotation. At this time, the couplings (triangular shapes) 76 and 39 between the photosensitive drum and the apparatus main body are misaligned so that they do not mesh with each other, and even if the drive motor 70 (70a to 70d) is rotated, the photosensitive drum 1 (1a to 1d) is rotated. ) Does not rotate. Further, the rotation of the developing roller 40 is performed only when an image is formed. This is for preventing deterioration of the developer by not stirring the developer when unnecessary. Therefore, the developing roller 40 does not rotate during this initial rotation. Therefore, the tooth contact state remains unresolved, and the initial rotation ends without engaging the photosensitive drum 1 and the coupling (triangular shape) 76, 39 on the apparatus main body side. That is, the gears 77 and 78 are brought into contact with each other without being engaged with each other.

  When such a phenomenon occurs, the conveying belt 11 that is in contact with the photosensitive drum 1 is rotated while the photosensitive drum 1 is stopped, so that a rubbing mark or a scratch is generated at the contact portion between the surface of the photosensitive drum 1 and the conveying belt 11. . When such rubbing marks are generated, the potential of the portion where the rubbing marks are generated fluctuates during image formation, causing a problem called a rubbing memory in which a horizontal streak of one rotation pitch of the photosensitive drum 1 appears on the image. To do.

  As a solution to such a problem, it is conceivable to simultaneously rotate and drive the conveyor belt 11 and the developing roller during initial rotation. As a result, even if tooth tip contact occurs, by rotating the gear 77 on the apparatus main body 100 side, the tooth tip contact is eliminated and the gears (couplings) 77 and 78 are engaged. In this way, the process cartridge 7 can be pulled into a predetermined position (position where it abuts against the abutting surfaces 37, 38 of the guide groove 34) by the pressing member 30. As a result, the misalignment between the couplings 76 and 39 is eliminated, and the couplings 76 and 39 can engage with each other and perform a normal operation. However, as described above, if the developing roller is rotationally driven other than during image formation, there is an adverse effect that the deterioration of the developer progresses. Therefore, a good image can be printed throughout the life of the process cartridge 7 by using the minimum necessary drive transmission. It becomes possible to do.

  Hereafter, the characteristic part of this Embodiment is demonstrated.

  FIG. 12 is a block diagram showing the configuration of the main part of the laser printer 100 according to the first embodiment. The same parts as those in the above-mentioned drawings are indicated by the same symbols, and the description thereof is omitted.

  The controller unit 1200 controls the overall operation of the printer 100. A display unit 1201 is provided in the operation unit of the printer 100 and displays messages and various data for the user. A power source 1202 supplies power to each unit of the printer 100. The driving source 1203 rotationally drives the cam 80 described above. The storage element 1204 is a memory such as an EEPROM or a flash memory. The storage element 1204 is provided in the cartridge 7 and stores, for example, a time during which the cartridge 7 is used, a toner consumption (toner remaining amount), and the like. The drive voltage means 78 corresponds to the coupling 78 described above. The coupling gear 71 and the drive voltage gear 77 correspond to the coupling gears 71 and 77 described above. The drive source 70 is a motor for driving the rotation of the photosensitive drum 1 described above. The cam 80 is the separation cam described above.

  FIG. 13 is a flowchart for explaining control processing by the controller unit 1200 of the laser printer 100 according to the present embodiment.

  First, in step S1, initial rotation is started, the presence or absence of the process cartridge 7 is detected, and whether or not the process cartridge 7 is attached to the main body is detected. If the cartridge 7 is not mounted, the process proceeds to step S2, and a warning is displayed to the user that the cartridge 7 is not mounted. In step S1, it waits for the cartridge 7 to be mounted.

  When the cartridge 7 is mounted in step S1, the process proceeds to step S3, and detection control is performed to determine whether the coupling is defective. In step S <b> 3, a rotation start signal is output to the drive motor 70 that transmits the drive to the photosensitive drum 1. Next, in step S4, it waits for a predetermined time, for example, 2.3 to 2.35 seconds, and when this predetermined time elapses, the process proceeds to step S5 to output a rotation stop signal and rotate the drive motor 70. To stop. Next, in step S6, the rotational speed of the drive motor 70 is measured 250 msec after the rotation stop signal of the motor 70 in step S5. In step S7, it is determined whether the rotational speed of the drive motor 70 is larger or smaller than a threshold value (500 rpm in the present embodiment). If the rotational speed is larger than the threshold value (500 rpm in the present embodiment), it is determined that the coupling is normal, the process proceeds to step S10, and the process proceeds to the standby state.

  On the other hand, if the rotational speed is smaller than the threshold value (500 rpm in the present embodiment) in step S7, it is determined that the coupling is not normal and the process proceeds to step S8, where it is determined whether the number of retries is the second time. When the number of retries is the first time, the process proceeds to step S9, where the developing roller 40 is rotated minutely to eliminate the tooth contact. Thereafter, the process proceeds to step S3, and the coupling failure is detected again.

  If it is determined in step S8 that the number of retries is the second, the process proceeds to step S11, where a display warning of a defective cartridge 7 is issued.

  Here, the initial rotation refers to an operation that is performed when a cover that needs to be opened or closed to replace the process cartridge 7 is opened or closed when the process cartridge 7 is replaced, when power is turned on, or when jamming is performed.

  As described above, according to this embodiment, when the coupling failure of the cartridge occurs, the developing roller 40 is rotated by a minute amount to eliminate the tooth tip contact, thereby causing the photosensitive drum to wear due to the tooth tip contact. Can be prevented.

  FIG. 14 is a graph for explaining the reason why a coupling failure can be determined in the present embodiment.

  When the couplings 77 and 78 of the photosensitive drum 1 are normally engaged, the rotational load torque of the photosensitive drum 1 is applied. Therefore, when the rotation stop signal is output after the rotation of the drive motor 70 is started, the rotation of the drive motor 70 is stopped in about 200 to 280 msec. However, when the coupling is defective, the load of the rotational load torque is not applied, so it takes 500 msec or more to stop the rotation of the motor. Accordingly, it can be determined that a coupling failure occurs when the rotational speed of the drive motor 70 is large with respect to a predetermined threshold (e.g., corresponding to 250 msec), and that the meshing is normal when the rotational speed is small.

  Next, the minute rotation driving of the developing roller 40 in step S9 in FIG. 13 will be specifically described.

  First, the clutch 74 of the drive train of the developing roller 40 is connected. Next, the drive motor 70 is rotated for a minimum time during which the gear 77 on the apparatus main body side can rotate at least two or three teeth, and the rotation of the drive motor 70 is stopped. Finally, the clutch 74 is disconnected. Thus, by rotating the gear 77 on the apparatus main body side by several teeth, the tooth tip contact state can be eliminated.

  Further, the presence / absence detection of the process cartridge in step S1 can be performed by using the storage element 1204 or by providing a cartridge 7 attachment / detachment sensor. In this embodiment mode, determination is made by reading data in the memory element 1204.

  Even if there is no means for detecting whether or not the process cartridge 7 is mounted, the above control is effective. In this case, steps S1 and S2 are omitted in the flowchart of FIG. If an error is detected at this time, a message indicating that the process cartridge 7 is not installed correctly or no process cartridge 7 is present can be displayed to warn the user.

  By performing such control, it is possible to obtain a good image while reducing the rotation of the developing roller 40 and preventing the deterioration of the developing material.

  Further, even when a phenomenon of tooth tip contact occurs, the apparatus can be put into a standby state without any harmful effects. Further, it is not necessary to provide a mechanism for solving the problem without unnecessarily extending the initial rotation time. For this reason, there is an effect that the apparatus main body can be reduced in size and cost.

<Embodiment 2>
Next, a second embodiment of the present invention will be described.

  FIG. 15 is a block diagram illustrating the configuration of the laser printer 100 according to Embodiment 2 of the present invention. As apparent from comparison with FIG. 12 of the first embodiment described above, FIG. 15 is different in that a drive motor 1300 for the drive transmission gear 77 is provided. Other configurations of the printer 100 are the same as those of the first embodiment.

  FIG. 16 is a perspective view of the drive unit of the process cartridge according to Embodiment 2 of the present invention.

  In the second embodiment, the unit for driving the process cartridge 7 is provided with drive motors 70 and 70 'for driving the photosensitive drum 1 and the developing roller 40 independently for each color. Further, outer rotor motors (DC motors) are employed as the drive motors 70 and 70 '. Therefore, the rotation and stop of the developing roller 40 can be arbitrarily switched regardless of the rotation of the photosensitive drum 1. The rotational driving force from the apparatus main body 100 side is generated by the photosensitive member drive transmission means and the development drive transmission means that are functionally connected to the drive unit on the apparatus main body 100 side with the process cartridge 7 mounted on the apparatus main body 100. These are transmitted to the photosensitive drum 1 and the developing roller 40, respectively.

  Here, as shown in FIG. 10, the photosensitive member drive transmission means is a drive transmission means using a coupling, and a gear 71 rotating integrally with the coupling 76 on the apparatus main body 100 side is an axis of the photosensitive drum 1. It is configured to be separated by sliding in the direction. The process cartridge 7 can be attached / detached by opening the cover on the front surface of the apparatus main body and simultaneously rotating the transport belt unit 5 to the attachment / detachment position of the process cartridge 7. The separation mechanism for separating and coupling the coupling 76 is interlocked with the rotation operation of the transport belt unit 5. That is, when the process cartridge 7 can be attached and detached, the process cartridge 7 is separated, and when the process cartridge 7 is moved to the image forming position, the coupling 76 is engaged. The developing roller drive transmission means is drive transmission means using gears. The gear 77 on the apparatus main body side is fixed, and the gears mesh with each other when the process cartridge 7 is mounted.

  With such a drive configuration, the drive of the photosensitive drums 1 for each color can be controlled independently. As a result, it is possible to control to reduce color misregistration that is always a problem in an inline-type full-color image forming apparatus. Further, the developing roller 40 can be rotated and stopped regardless of the driving of the photosensitive drum 1.

  When the process cartridge 7 is attached to the apparatus main body 100, the drive transmission means of the developing roller is a drive transmission by a gear, and the position of the gear 77 on the apparatus main body side is fixed. For this reason, as described with reference to FIG. 11 described above, depending on the phase of the gear, when the teeth are correctly meshed with each other, there are cases where the tooth tips come into contact with each other.

  In this state, when the cover is closed and the power is turned on, the apparatus 100 starts initial rotation. At this time, since the couplings 76 and 39 are misaligned, they cannot be engaged with each other, and even if the drive motor 70 is rotated, the photosensitive drum 1 does not rotate. Further, since the developing roller is driven only when an image is formed, the developing roller does not rotate during the initial rotation. Therefore, the state of contact with the teeth remains unresolved, and the initial rotation ends without the couplings 76 and 39 of the photosensitive drum 1 being engaged. When such a phenomenon occurs, as described above, a rubbing mark or a scratch is generated at the contact portion of the surface of the photosensitive drum 1 with the transport belt 11 to cause a problem.

  Thus, in the second embodiment, the same control as in the first embodiment (FIG. 13) is performed. In the developing roller driving micro-rotation control (step S9) according to the second embodiment, the driving motor 70 ′ is rotated by a minimum time during which the gear 77 on the apparatus main body side can rotate at least two to three teeth. 'Stop. The tooth tip contact state can be eliminated by rotating the gear 77 on the apparatus main body side by several teeth. Therefore, the tooth contact state can be eliminated without rotating the photosensitive drum 1 at all. As a result, it is possible to more effectively solve problems such as rubbing memory. Further, the clutch connection / separation operation becomes unnecessary, and the operation time can be shortened.

  Here, in the second embodiment, a DC motor is used as the drive motor 70 ′ of the developing roller 40, but another drive source such as a stepping motor may be used.

  The configuration described in the above embodiment is not limited to an image forming apparatus using a conveyance belt, but is similarly effective for an image forming apparatus using a photosensitive belt and an intermediate transfer member.

  As described above, according to the present embodiment, a coupling failure that occurs at the same time when the tooth tip contact between gears between the process cartridge inserted into the image forming apparatus and the apparatus main body occurs is detected, Control for eliminating tooth tip contact is executed. As a result, the apparatus main body can be put into a standby state without causing problems such as image defects.

  Further, since control for solving the problem is performed only when a coupling problem occurs, unnecessary time is not spent for initial rotation in a state where no problem occurs.

  Furthermore, since it is not necessary to provide a mechanism for eliminating the tooth tip contact, the apparatus can be reduced in size and cost. Therefore, the above problem can be solved.

  Further, the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or an apparatus composed of a single device (for example, a copier, a facsimile machine, etc.). It may be applied.

  Another object of the present invention is to mount a storage medium recording software program codes for realizing the functions of the above-described embodiments in a system or apparatus, and read and execute the installed program codes from the storage medium. Is also achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, the functions of the above-described embodiment are realized by executing the program code read by the computer. In addition, the operating system (OS) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. It is.

  Furthermore, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, and the CPU of the main body executes part or all of the processing. Thus, the functions of this embodiment may be realized.

  The storage medium for supplying the program includes, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, and nonvolatile memory. There are cards. Furthermore, ROM and DVD (DVD-ROM, DVD-R) are also included.

  Alternatively, the browser of the client computer may be used to connect to a homepage on the Internet, and the computer program itself of the present invention or a compressed file including an automatic installation function may be downloaded from the homepage to a storage medium. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the claims of the present invention.

  Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

1 is a diagram illustrating an overall configuration of a laser printer that is an aspect of a color image forming apparatus according to an embodiment of the present invention. FIG. FIG. 3 is a main cross-sectional view of a process cartridge according to the present embodiment. It is an assembly perspective view of a process cartridge according to the present embodiment. FIG. 5 is a perspective view showing the vicinity of a side plate in the apparatus main body for explaining a process cartridge mounting method according to the present embodiment. It is a fragmentary sectional view showing a positioning part to an image forming device of a process cartridge concerning this embodiment. It is a fragmentary sectional view showing a positioning part to an image forming device of a process cartridge concerning this embodiment. FIG. 4 is a perspective view showing a mechanism for switching separation and contact between the photosensitive drum and the developing roller according to the present embodiment. It is a perspective view of the drive part of the process cartridge which concerns on this Embodiment. It is a cam diagram which concerns on this Embodiment. FIG. 5 is a perspective view illustrating a photosensitive member drive transmission unit according to the present embodiment. It is a figure explaining a tooth tip contact state in an embodiment of the invention. FIG. 2 is a block diagram illustrating a configuration of a main part of the laser printer according to the first embodiment. It is a flowchart explaining the control processing by the controller part of the laser printer which concerns on this Embodiment. It is a graph explaining the reason why a coupling failure can be determined in the present embodiment. It is a block diagram explaining the structure of the laser printer which concerns on Embodiment 2 of this invention. It is a perspective view of the drive part of the process cartridge which concerns on Embodiment 2 of this invention. It is a figure which shows the state of (5) of FIG. 9 in the laser printer which concerns on embodiment of this invention. It is a figure which shows the state of (8) of FIG. 9 in the laser printer which concerns on embodiment of this invention.

Claims (13)

An image forming apparatus that is detachably attached to an image forming apparatus and that mounts a cartridge including at least an image carrier and a developing roller to form an image on a recording medium,
Detecting means for detecting poor connection with the cartridge;
A developing driving means for rotating the developing roller by a predetermined amount when the connection failure is detected by the detecting means;
An image forming apparatus comprising:   The detecting means detects the connection failure based on a time from when the drive motor of the image carrier is rotated to when the rotation of the drive motor stops from a stop signal for stopping the rotation. The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 1, wherein the predetermined amount is a rotation amount corresponding to a predetermined number of pitches of a gear that transmits rotation to the developing roller. And a drive source for rotating the image carrier and the developing roller,
The image forming apparatus according to claim 1, further comprising a transmission unit that selectively transmits a driving force from the driving source to the image carrier and the developing roller. Furthermore, two drive sources that respectively rotate and drive the image carrier and the developing roller;
4. The image forming apparatus according to claim 1, further comprising a transmission unit configured to transmit a driving force from the two driving sources to the image carrier and the developing roller. 5.   6. The image forming apparatus according to claim 4, wherein the driving source includes a DC motor.   The image bearing member and the driving source are engaged by coupling, and the developing roller and the driving source are engaged by gears. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the detection unit detects a connection failure when the cartridge is mounted on the image forming apparatus. A control method for an image forming apparatus, which is detachable from an image forming apparatus and mounts a cartridge including at least an image carrier and a developing roller to form an image on a recording medium,
A detection step of detecting a connection failure with the cartridge;
A development driving step of rotating the developing roller by a predetermined amount when the poor connection is detected in the detection step;
A control method for an image forming apparatus, comprising:   In the detecting step, after the rotation of the driving motor for the image carrier, the connection failure is detected based on a time from the stop signal for stopping the rotation until the rotation of the driving motor stops. The method of controlling an image forming apparatus according to claim 9.   The method of controlling an image forming apparatus according to claim 9, wherein the predetermined amount is a rotation amount corresponding to a predetermined number of pitches of a gear that transmits rotation to the developing roller.   12. The image forming apparatus according to claim 9, wherein the image carrier and the drive source of the image forming apparatus are engaged by coupling, and the developing roller and the drive source are engaged by a gear. 2. A method for controlling an image forming apparatus according to item 1.   13. The image forming apparatus control method according to claim 9, wherein the detecting step is executed when the cartridge is mounted on the image forming apparatus.

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