JP2006235518A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that substantially prevents print fogging from occurring, by hindering a small amount of toner from being mixed into a large amount of deteriorating old toner. <P>SOLUTION: When toner empty is detected (S1: YES), the supply of toner to a developing cartridge from a toner cartridge is stopped, and recovery control is initiated such that toner is only returned to the toner cartridge from the developing cartridge (S5). Only when the recovery control is terminated, the toner cartridge is allowed to be replaced with a new one (S8). As a result, when a new toner cartridge is attached, little toner (deteriorated old toner) is left in the developing cartridge. Accordingly, even when new toner is supplied from the toner cartridge after the replacement, print fogging is substantially prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a so-called electrophotographic image forming apparatus that forms an image by developing an electrostatic latent image formed on an electrostatic latent image carrier with toner and attaching the image to a recording medium, and the image formation The present invention relates to a process cartridge usable in the apparatus.

  Conventionally, an electrostatic latent image carrier on which an electrostatic latent image is formed, a toner cartridge in which toner used for developing the electrostatic latent image is stored, and a toner cartridge stored in the toner cartridge Development means for developing the electrostatic latent image by attaching toner to the surface of the electrostatic latent image carrier, and toner attached to the surface of the electrostatic latent image carrier by the development means on the recording medium An image forming apparatus including a transfer unit for transferring, and a developing device in which the toner cartridge is detachable and at least the developing unit is accommodated is considered. In this type of image forming apparatus, when an electrostatic latent image is formed on the surface of the electrostatic latent image carrier, the developing means attaches the toner contained in the toner cartridge to the surface of the electrostatic latent image carrier. The electrostatic latent image is developed. Subsequently, the toner adhering to the surface of the electrostatic latent image carrier by the developing unit as described above is transferred to the recording medium by the transfer unit, so that the electrostatic latent image corresponds to the recording medium. Images can be formed. Further, since the developing device containing the developing means is configured so that the toner cartridge can be attached and detached, when the toner is consumed, the toner cartridge can be replaced and image formation can be continued.

Further, in this type of image forming apparatus, in order to supply the toner contained in the toner cartridge to the developing device, a supply means such as an agitator is provided in the toner cartridge, and the toner supplied to the developing device is further supplied with the toner cartridge. In order to return to the above, it has also been proposed to provide a return means such as an auger in the housing of the developing device. In this case, the toner can be circulated between the developing device and the toner cartridge by simultaneously operating the supply unit and the return unit. As a result, it is possible to prevent the toner from aggregating and becoming hard at one place, and as a result, the fluidity of the toner can be secured and the image quality can be improved (for example, see Patent Document 1). ).
JP-A-9-319201

  However, in this type of image forming apparatus, when the toner cartridge is replaced, the image quality may be deteriorated for the following reason. That is, it is known that the toner is deteriorated by repeating the image formation, and this is particularly noticeable by rubbing with a layer thickness regulating member or the like in non-magnetic one-component development. In addition, due to the deterioration of the toner, the charging performance of the toner may be lowered, and there may be a difference in chargeability depending on whether the toner is new or old. Here, if the old and new toners are mixed and rubbed together, the deteriorated toner and the new toner have superior and poor charging performance, and the charge amount is offset, so both toners are not charged to the same polarity, New toner is positively charged, and old deteriorated toner is negatively charged. When this negatively charged toner adheres to a positively charged portion of the electrostatic latent image, that is, a portion that is originally so-called white solid, a so-called printing fog is generated.

  However, if a large amount of positively charged new toner exists in the vicinity of the developing means such as the developing roller, the new toner having a high charge amount preferentially adheres to the developing roller due to the mirror image force, and the old toner is hardly used. Since it does not adhere to the developing roller, printing fog does not occur.

  However, when new toner enters a place where there is a large amount of negatively charged old toner near the developing roller, the negatively charged old toner preferentially adheres to the developing roller due to mirror image force, Print fog occurs. When a new toner cartridge is installed and new toner is supplied from there, this condition may be satisfied and printing fog may occur.

  Accordingly, an object of the present invention is to provide an image forming apparatus in which a small amount of new toner is mixed in a place where a large amount of deteriorated old toner is present, and print fog is hardly generated. It was.

  The present invention made to achieve the above object includes an electrostatic latent image carrier on which an electrostatic latent image is formed, and a toner cartridge in which toner used for developing the electrostatic latent image is accommodated. And developing means for developing the electrostatic latent image by adhering the toner contained in the toner cartridge to the surface of the electrostatic latent image carrier, and developing the electrostatic latent image carrier on the surface of the electrostatic latent image carrier. An image forming apparatus comprising: a transfer unit that transfers adhered toner to a recording medium; and a developing device in which the toner cartridge is detachable and contains at least the developing unit. Supply means for supplying the accommodated toner to the developing device; and return means operable to be independent of the supply means and returning the toner supplied to the developing device to the toner cartridge. Image forming apparatus, characterized in that was e.

  In the present invention configured as described above, the toner can be circulated between the toner cartridge and the developing device by simultaneously operating the supply unit and the return unit. In this way, when the toner is circulated and homogenized, it is possible to prevent the deteriorated old toner from aggregating and becoming hard at one place, and to ensure the fluidity of the toner, thereby improving the image quality. Can be improved.

  In the present invention, since the return means can operate independently of the supply means, when replacing the toner cartridge, the supply means is stopped and the return means is operated to remove the toner inside the developing device. Can be returned to the cartridge. If the toner cartridge is replaced in this state, the amount of toner (deteriorated old toner) is reduced in the developing device. Therefore, even if toner is supplied from a new toner cartridge, a small amount of deteriorated old toner is reduced. It is possible to prevent the new toner from being mixed. Therefore, in the present invention, it is possible to satisfactorily suppress the occurrence of print fog.

  The present invention does not limit the configuration of the return means, but the return means may return the toner to the toner cartridge while circulating the toner inside the developing device. . In this case, by circulating the toner inside the developing device, it is possible to further homogenize the toner, and to better suppress the mixing of a small amount of new toner that has not deteriorated with a large amount of deteriorated old toner. be able to.

  In the image forming apparatus of the present invention, the developing device may be configured to be detachable. In this case, the developing device can be replaced in accordance with the deterioration of the developing means, and the maintainability is improved. The electrostatic latent image carrier may be configured to be detachable. In this case, the electrostatic latent image carrier can be replaced in accordance with the deterioration of the electrostatic latent image carrier, and the maintainability is improved.

  In the image forming apparatus of the present invention, when the return unit operates while the supply unit is stopped, the developing unit may stop operating. Since the developing means conveys the toner toward the electrostatic latent image carrier, the toner can be returned to the toner cartridge more efficiently by stopping the developing means in this way. Therefore, in this case, it is possible to further suppress the mixing of a large amount of deteriorated old toner with a small amount of new toner that has not deteriorated, and further suppress the occurrence of printing fog.

  Still further, the image forming apparatus of the present invention includes a replacement timing detection unit that detects a replacement timing of the toner cartridge, and the return unit while the supply unit is stopped when the replacement timing detection unit detects the replacement timing. Control means for executing recovery control for operating the means may be further provided. In this case, when the toner cartridge reaches the replacement time, this is detected by the replacement time detection means, and the control for automatically returning the toner inside the developing device to the toner cartridge as described above is automatically performed by the control means. Can be executed.

  In this case, the apparatus further includes attachment / detachment detection means for detecting attachment / detachment of the toner cartridge or opening / closing of the attachment / detachment opening of the toner cartridge, and the replacement timing detection means is based on the amount of toner contained in the toner cartridge. After the replacement time is detected and the control means executes the collection control, when the attachment / detachment detection means detects attachment / detachment of the toner cartridge or opening / closing of the attachment / detachment opening of the toner cartridge, the control means The detection result of the replacement time detection means may be referred to after operating the supply means by a predetermined amount.

  Even if the replacement timing of the toner cartridge is detected by the replacement timing detection means, there is a case where the old toner cartridge that has been mounted up to that time is erroneously mounted again without replacing the toner cartridge with a new one. In such a case, a large amount of toner is stored in the toner cartridge by the above-described collection control. For this reason, when the replacement time detection means detects the replacement time based on the amount of toner contained in the toner cartridge, there is a possibility that an erroneous detection of the replacement time may occur in the subsequent control. Therefore, in the present invention, after the toner cartridge is replaced, the supply unit is driven by a predetermined amount, and the detection result of the replacement timing detection unit is referred to. For this reason, in this invention, the further effect that the misdetection of replacement | exchange time can be prevented arises. The predetermined amount may be set in advance to an appropriate amount according to the form of the toner cartridge and the supply means so that erroneous detection can be prevented as described above.

  In the image forming apparatus according to each aspect of the invention, the toner may be a non-magnetic single component toner. With non-magnetic one-component toner, if a large amount of deteriorated toner is mixed with a small amount of undegraded toner, the image quality is likely to be affected. However, as described above, such a situation can be satisfactorily avoided in the present invention. it can. Therefore, in this case, the effects of the above-described inventions become more prominent.

  Further, the process cartridge of the present invention made to achieve the above object is equipped with a toner cartridge in which toner used for developing an electrostatic latent image formed on the surface of the electrostatic latent image carrier is accommodated. A process that is configured to be capable of being attached to the surface of the latent electrostatic image bearing member to develop the latent electrostatic image and is detachable from the image forming apparatus. The cartridge is characterized in that it is operable independently of the toner supply operation from the toner cartridge, and is provided with a return means for returning the toner in the process cartridge toward the toner cartridge. If the image forming apparatus is configured by using the process cartridge of the present invention, the return means can operate independently of the toner supply operation from the toner cartridge. Therefore, when the toner cartridge is replaced, the supply operation is stopped. By operating the return means, the toner inside the process cartridge can be returned to the toner cartridge. Therefore, the image forming apparatus of the invention can be easily configured, and the same effect as that of the image forming apparatus of the invention is produced. That is, it is possible to suppress the mixing of a small amount of new toner that has not deteriorated with a large amount of deteriorated old toner, and the occurrence of print fogging can be suppressed.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an appearance of a laser printer 1 as an image forming apparatus to which the present invention is applied. The laser printer 1 according to the present embodiment forms an image with a positively chargeable non-magnetic one-component toner.

  As shown in FIG. 1, a paper feed cassette 3 is attached to the lower part of a cover 2 that covers the main body of the laser printer 1 from the outer periphery, and the front surface of the cover 2 (that is, the surface disposed in front of the laser printer 1 when installed). ) Is provided with a cover 4 of the cover 2.

  The lid portion 4 is provided with finger hooking portions 4a above both left and right ends. By pulling the finger hooking portions 4a, the lid portion 4 can be opened to the front with the hinge 4b at the lower end as the center as shown in FIG. Further, as shown in FIG. 3, the paper feed cassette 3 is provided so as to be able to be pulled out toward the front, and the paper feed cassette 3 can be attached to and detached from the laser printer 1 by being drawn out in this way.

  Next, FIG. 4 is a longitudinal sectional view showing the internal configuration of the laser printer 1. 4 corresponds to a cross-sectional view taken along line AA in FIG. As shown in FIG. 4, a support plate 5 urged upward by a spring 6 is provided inside the paper feed cassette 3, and on the support plate 5 on the front side further above the support plate 5. A paper feed roller 9 is provided that separates sheets (not shown) as recording media held in a stacked state one by one and supplies them in the direction of the image forming unit 7. In addition, in the paper conveyance path from the paper supply roller 9 to the image forming unit 7, the conveyance roller 11 that conveys the paper in cooperation with the paper supply roller 9 and the paper conveyed by the conveyance roller 11 are fed. A guide 13 that turns back about 180 ° along the outer periphery of the roller 9 and a pair of registration rollers 14 and 15 that lock the leading edge of the paper by appropriately stopping and correct the skew of the paper are sequentially arranged. ing.

  The image forming unit 7 includes a photosensitive drum 21 as an electrostatic latent image carrier provided in the photosensitive cartridge 20, and a transfer roller 22 as a transfer unit arranged to face the photosensitive drum 21. The sheet on which the toner image is formed as described later after passing between the photosensitive drum 21 and the transfer roller 22 is supplied to the fixing unit 31. In the fixing unit 31, the toner image formed on the sheet is sandwiched between the heating roller 33 and the pressing roller 35 and thermally fixed, and the sheet on which the image is fixed is further conveyed by a pair of conveying rollers 36 and 36. .

  The paper transported by the transport rollers 36 and 36 is guided to the upper side of the cover 2 by the guide 37 and discharged to a paper discharge tray 39 provided on the upper surface of the cover 2 by a pair of paper discharge rollers 38 and 38. A scanner unit 90 that exposes the photosensitive drum 21 with the laser beam L is disposed between the paper discharge tray 39 and the photosensitive cartridge 20.

  Next, the configuration of the image forming unit 7 and the scanner unit 90 will be described in more detail. The photoconductor cartridge 20 is rotatably provided with a photoconductor drum 21 having a photoconductive layer on its surface, and further includes a transfer roller 22 and a scorotron charger 23 as a charging unit that uniformly charges the surface of the photoconductor drum 21. It has. An electrostatic latent image is formed on the surface of the photosensitive drum 21 charged by the scorotron charger 23 by the laser light L incident from the scanner unit 90 through the exposure opening 20a. Subsequently, a developing roller 41 as a developing unit provided in the developing cartridge 40 described below supplies toner to the surface of the photosensitive drum 21, whereby the electrostatic latent image is developed. The toner attached to the photosensitive drum 21 in this manner is transferred to a sheet passing between the transfer roller 22 and an image is formed on the sheet by the above operation. Further, a paper dust collecting brush 24 to which a positive bias is applied is in contact with the surface of the photosensitive drum 21 after image formation, and the paper dust (negatively charged) adhering from the paper to the photosensitive drum 21 is contacted. It has been removed.

  As shown in FIG. 4, the developing roller 41 is rotatably supported by the developing cartridge 40, and is driven to rotate by a mechanism described later in contact with the photosensitive drum 21. The developing cartridge 40 includes a support portion 42 as a cartridge mounting portion that detachably supports the toner cartridge 60, and an opening 42 a through which toner is supplied from the toner cartridge 60 is formed in the support portion 42 ( (See FIG. 7). Further, the developing cartridge 40 is conveyed by an upper auger 43 and a lower auger 44 that circulate toner supplied from an opening 42 a provided in the central portion in the axial direction to both sides in the axial direction, and the upper auger 43 and lower auger 44. A supply roller 45 that supplies the toner to the developing roller 41 and a developing blade 47 that frictionally charges the toner attached to the surface of the developing roller 41 by the supply roller 45 to form a thin layer of toner are provided. ing. An agitator 61 for agitating the supplied toner and supplying it to the developing cartridge 40 side is rotatably provided inside the toner cartridge 60.

  Next, the configuration of the scanner unit 90 will be described. The scanner unit 90 includes a polygon mirror 91 that deflects and scans a laser beam L generated by a laser light emitting unit (not shown), and mirrors 92 and 93 that return the laser beam L deflected to the polygon mirror 91 toward the photosensitive drum 21. It has. Further, an fθ lens 95 is fixed to the optical path of the laser light L from the polygon mirror 91 to the mirror 92, and a cylindrical lens 97 is fixed to the optical path of the laser light L from the mirror 92 to the mirror 93.

  With the above configuration, an electrostatic latent image can be formed on the surface of the photosensitive drum 21 by emitting the laser light L at an appropriate timing while rotating the polygon mirror 91 and the photosensitive drum 21. Then, as described above, the electrostatic latent image is developed with toner via the developing roller 41 and transferred onto a sheet, thereby enabling image formation by electrophotography.

  Next, as shown in FIG. 5, when the lid portion 4 is opened and the handle 25 of the photosensitive cartridge 20 is further pulled forward, the photosensitive cartridge 20 is integrated with the developing cartridge 40 and the toner cartridge 60, and the attachment / detachment opening 2a. To the outside of the main body of the laser printer 1. The attachment / detachment opening 2 a is an opening of the cover 2 that is closed by the lid 4.

  Further, as shown in FIG. 6, when the handle 62 of the toner cartridge 60 is rotated upward, the toner cartridge 60 is divided from the developing cartridge 40 as will be described later, and when the handle 62 is further pulled forward, FIG. As shown in FIG. 4, only the toner cartridge 60 can be taken out from the apparatus main body of the laser printer 1 through the attachment / detachment opening 2a.

  Furthermore, as shown in FIG. 8, when the handle 25 of the photosensitive cartridge 20 is pushed down, the leaf spring 26 that engages and fixes the developing cartridge 40 is pushed down, and the handle 62 of the toner cartridge 60 is further rotated upward. If the toner cartridge 60 and the developing cartridge 40 are pulled to the front without being moved, the toner cartridge 60 and the developing cartridge 40 are integrally separated from the apparatus body of the laser printer 1 through the attachment / detachment opening 2a without being divided. Can do.

  Next, the configuration of each part constituting the image forming unit 7 will be described. FIG. 9 is a left side view illustrating the configuration of the photoconductor cartridge 20. In the following description, the near side in FIG. 4 is defined as the left side. As shown in FIG. 9, the handle 25 of the photoconductor cartridge 20 is fixed to the photoconductor cartridge 20 via a leaf spring 26. The leaf spring 26 has a bent portion 26a bent upward in a stepwise manner. When the developing cartridge 40 is attached to the photosensitive cartridge 20, the bent portion 26a is formed at the lower edge of the support portion 42. By engaging, the photosensitive cartridge 20 and the developing cartridge 40 are connected. Therefore, when the handle 25 is pushed down as described above (see FIG. 8), the engagement between the bent portion 26a and the lower edge of the support portion 42 is released, and the developing cartridge 40 is attached to and detached from the photosensitive cartridge 20. It becomes possible.

  Further, the metal rotating shaft 21a of the photosensitive drum 21 protrudes from the photosensitive cartridge 20 to the left and right sides, and rotates integrally with the photosensitive drum 21 from the rear (mounting direction side) end of the photosensitive cartridge 20. The gear 21b is exposed.

  On the other hand, as shown in FIG. 10, a guide groove 121 that guides the rotating shaft 21a is formed on the left inner wall surface of the main body of the laser printer 1, and a gear 121b that meshes with the gear 21b is provided. The gear 121b is configured to be drivable by a drum motor 122 (see FIG. 18). When the photoconductor cartridge 20 is mounted, the gears 21b and 121b are engaged with each other to transmit a driving force from the main body side to the photoconductor drum 21. It becomes possible.

  Next, FIG. 11 is a left side view illustrating a state in which the toner cartridge 60 is attached to the developing cartridge 40. As shown in FIG. 11, a drive shaft 51 to which a driving force is transmitted from the drive shaft 151 on the main body side is provided on the left side surface of the developing cartridge 40. The drive shaft 151 is provided with a flat plate-like convex portion 151a on the end surface, and the drive shaft 51 is formed as a cylindrical concave portion into which the drive shaft 151 can be fitted and a projection 51a that can be engaged with the flat plate-like convex portion 151a is formed. Both constitute a so-called drive coupling.

  As shown in FIG. 11, a gear 51 b that rotates integrally with the drive shaft 51 is formed. The gear 51 b includes a gear 41 a that rotates together with the developing roller 41, a gear 45 a that rotates together with the supply roller 45, and , Meshed with the gear 53 exposed on the left inner wall surface of the support portion 42.

  Further, the toner cartridge 60 is configured as follows, and can be switched between connection and disconnection with the developing cartridge 40. 12A and 12B show a state in which the handle 62 of the toner cartridge 60 is disposed at a position rotated upward (hereinafter referred to as a dividing position) as shown in FIG. 12A is a view of the support portion 42 of the developing cartridge 40 as viewed from the toner cartridge 60 side, and FIG. 12B is a view of the toner cartridge 60 as viewed from the support portion 42 side.

  As shown in FIG. 12B, the toner cartridge 60 includes a long cylindrical inner cylinder 63 in which toner is accommodated, and an outer cylinder 64 that is externally fitted to the center of the inner cylinder 63. Yes. The outer cylinder 64 is non-rotatably attached to the support portion 42 by engaging a protrusion 64 a protruding toward the support portion 42 with a long groove 42 b formed on the inner wall surface of the support portion 42. The inner cylinder 63 is integrally formed with the handle 62 described above, and is configured to be rotatable inside the outer cylinder 64 in accordance with the operation of the handle 62.

  Also, as shown in FIG. 12A, a shutter 48 made of a metal plate is disposed inside the support portion 42. The shutter 48 is supported at both ends by rails 42c formed on the inner wall surface of the support portion 42, thereby closing the opening 42a of the support portion 42 as shown in FIG. It is arranged so as to be movable in the inner circumferential direction of the support portion 42 between a position (see FIG. 12C) arranged to be displaced upward.

  Four protrusions 63 a are formed on the surface of the inner cylinder 63 to sandwich the vicinity of both ends of the shutter 48 from both sides in the circumferential direction. For this reason, when the shutter 48 is moved according to the rotation of the inner cylinder 63 and the handle 62 is rotated to the dividing position, as shown in FIG. 12 (A), the shutter 48 is a position that closes the opening 42a. It is arranged. The long groove 42b described above is further formed below the shutter so as not to overlap the shutter 48 disposed at this position. Moreover, the opening part 42a is comprised by the rectangular shape long in a horizontal direction, and the rectangular frame-shaped sponge 49 surrounding the opening part 42a is affixed on the inner wall surface of the support part 42 of the circumference | surroundings.

  An opening 64b having the same shape as the opening 42a is formed in a portion of the outer cylinder 64 that faces the opening 42a when the protrusion 64a is engaged with the long groove 42b. A shaped sponge 65 is affixed. The inner cylinder 63 also has an opening 63b having the same shape as the opening 64b. However, as shown in FIG. 12B, when the handle 62 is disposed at the dividing position, the opening 64b. And the opening 63b do not overlap at all. For this reason, even when the toner cartridge 60 is removed, the toner inside does not spill.

  Then, when the protrusion 64a is engaged with the long groove 42b and the handle 62 of the toner cartridge 60 is rotated downward as shown in FIG. 8 (hereinafter, this position of the handle 62 is referred to as a coupling position), FIG. 12 (D), the opening 64b and the opening 63b overlap. At this time, the shutter 48 is moved by the protrusion 63a to the upper part of the opening 42a as shown in FIG. 12C, so that the opening 64b and the opening 42a communicate with each other, and the toner cartridge 60 and the developing cartridge. The toner can be supplied to 40.

  Further, at this time, the sponge 49 and the sponge 65 are in close contact with each other, and the engaging portion 63c integrally formed on the outer peripheral surface of the inner cylinder 63 is engaged with the rail 42c, so that the openings 64b and 42a are sealed. As a result, toner does not spill outside. Further, the engagement between the engaging portion 63c and the rail 42c connects the developing cartridge 40 and the toner cartridge 60, and it is possible to attach and detach them together as described above (see FIG. 8). Conversely, by operating the handle 62 to rotate the inner cylinder 63 and releasing the engagement between the engaging portion 63c and the rail 42c, the developing cartridge 40 and the toner cartridge 60 are separated, as described above. Only the toner cartridge 60 can be taken out (see FIG. 7).

  A gear 61b that rotates integrally with the rotating shaft 61a of the agitator 61 is disposed outside the left end of the inner cylinder 63, and the gear 53 described above is located at a position facing the gear 61b in the support portion 42. Exposed. For this reason, the gear 53 meshes with the gear 61b when the toner cartridge 60 is mounted, and transmits the driving force transmitted to the driving shaft 51 to the rotating shaft 61a.

  Here, the agitator 61 is made of a resin material such as a flexible ABS resin, and the following members are integrally formed. That is, as shown in the sectional view of FIG. 13, the gear 61b and the rotation shaft 61a described above, the blade member 61c provided on the rotation shaft 61a, the flexible film member 61d provided on the blade member 61c, and the rotation shaft A wiper support 61e provided on 61a is integrally formed.

  The wiper support portion 61e is provided so as to protrude in a direction opposite to the protruding direction of the blade member 61c at both axial ends of the rotating shaft 61a. A wiper member 67 for wiping a toner remaining amount detection window 63d described below is fixed to each wiper support portion 61e. Each wiper member 67 is disposed so as to elastically contact the left and right inner wall surfaces of the inner cylinder 63 in order to wipe the remaining toner amount detection window 63d.

  The toner remaining amount detection window 63d is provided on the lower rear side of the inner cylinder 63 so as to face the left and right wall surfaces of the inner cylinder 63. Further, as shown in FIGS. 11 and 14, a circular light passing portion 42d is provided at a portion of the support portion 42 that faces the toner remaining amount detection window 63d.

  FIG. 14 is a right side view illustrating a state in which the toner cartridge 60 is mounted on the developing cartridge 40. As shown in FIG. 14, a drive shaft 54 is provided on the right side surface of the support portion 42, and this drive shaft 54 is connected to a drive shaft 154 (see FIG. 17) provided on the right side inner wall on the main body side and a so-called drive cup. Make up the ring. That is, the drive shaft 154 is provided with a flat plate-like convex portion 154a on the end surface, and the drive shaft 54 is formed as a cylindrical concave portion into which the drive shaft 154 can be fitted and a projection 54a that can be engaged with the flat plate-like convex portion 154a is formed. Has been. Further, a gear 54 b disposed on the right inner wall surface of the support portion 42 and rotating integrally with the drive shaft 54 meshes with gears 43 a and 44 a rotating integrally with the upper auger 43 and the lower auger 44, respectively.

  For this reason, when a driving force is transmitted from the driving shaft 154 to the driving shaft 54, the upper auger 43 and the lower auger 44 can be rotated by the driving force. Here, the upper auger 43 and the lower auger 44 are respectively formed with helical teeth 43b and 44b as shown in FIG. 15, and operate as follows by the rotation. That is, the lower auger 44 conveys the toner discharged from the opening 42a by the rotation of the agitator 61 in the left-right direction in the developing cartridge 40, and the upper auger 43 centers the toner accumulated on the left and right sides of the developing cartridge 40 in the center. The collected toner is returned to the toner cartridge 60 from the opening 42a.

  By the operations of the upper auger 43, the lower auger 44, and the agitator 61, the toner can be circulated between the developing cartridge 40 and the toner cartridge 60, and the toner can also be circulated in the developing cartridge 40. It is possible to prevent the toner from aggregating and hardening to ensure the fluidity of the toner. Note that the toner transport directions by the upper auger 43 and the lower auger 44 are indicated by arrows in FIG.

  Further, as shown in FIG. 15, a partition wall 55 is provided between the upper auger 43 and the lower auger 44 for smooth conveyance of the toner. FIG. 15 is a cross-sectional view of the developing cartridge 40 cut along the arrangement direction of the upper auger 43 and the lower auger 44. The configuration (gears 43a, 44a, etc.) disposed outside the developing cartridge 40 is shown in FIG. Illustration is omitted.

  Next, FIG. 16 is a partially enlarged view of FIG. 10, and shows a drive system on the main body side of the laser printer 1 for driving the drive shaft 151 described above. As shown in FIG. 16, the gear 151 b that rotates integrally with the drive shaft 151 meshes with the gear 171 that rotates integrally with the rotation shaft of the developing motor 170 via the gear 172. Therefore, when the developing motor 170 is driven, the developing roller 41, the supply roller 45, and the agitator 61 can be simultaneously driven via the drive shaft 51 as described above.

  Further, a drive system as shown in FIG. 17 is provided on the right inner wall surface of the main body of the laser printer 1 at a position facing the portion shown in FIG. As shown in FIG. 17, a guide groove 121 that guides the rotation shaft 21 a of the photosensitive drum 21 is also formed on the right inner wall surface, and the above-described drive shaft 154 is provided in the middle of the guide groove 121. A gear 154 b that rotates integrally with the drive shaft 154 meshes with a gear 176 that rotates integrally with the rotation shaft of the return motor 175. Therefore, if the return motor 175 is driven, the upper auger 43 and the lower auger 44 can be driven simultaneously via the drive shaft 54 as described above. The drive shafts 151 and 154 are provided so as to be able to protrude / retract, and are connected to a link mechanism (not shown) so as to protrude or retract in conjunction with closing or opening of the lid portion 4. When the lid portion 4 is opened, they are retracted, and the engagement between the drive shafts 151 and 154 and the drive shafts 51 and 54 is released. Therefore, the photosensitive cartridge 20, the developing cartridge 40, and the toner cartridge 60 can be attached and detached. Conversely, when the lid portion 4 is closed, they protrude, and the drive shafts 151 and 154 engage with the drive shafts 51 and 54. For this reason, it is possible to drive each of the aforementioned parts.

  As shown in FIGS. 12B and 13, a pair of spring receiving portions 66, 66 whose center in the circumferential direction is depressed are formed on the left and right sides on the surface of the inner cylinder 63 slightly above both sides of the handle 62. Has been. As shown in FIG. 2, a pair of pressing members 71, 71 urged in a protruding direction by a spring (not shown) is disposed on the inner surface of the lid portion 4, and the spring receiving portions 66, 66 close the lid portion 4. When pressed, it receives a pressing force from the pressing members 71, 71. The cartridges 20, 40, 60 are securely fixed in the apparatus by this pressing force. Further, an interference member 72 protrudes between the pressing members 71 and 71, and if the handle 62 is not disposed at the coupling position, the handle 62 and the interference member 72 interfere with each other to close the lid portion 4. It is configured not to be able to.

  Next, the control system of the laser printer 1 will be described. As shown in FIG. 18, the laser printer 1 includes a toner cartridge through the above-described cover sensor 198 such as a limit switch that detects the opening / closing of the lid 4 and the above-described toner remaining amount detection window 63d and the light passage portion 42d. And an empty sensor 199 such as a photocoupler that optically detects the presence or absence of toner in the toner cartridge 60. In the present embodiment, the empty sensor 199 includes a light emitting element 199a provided on the left inner wall surface of the main body of the laser printer 1 as shown in FIGS. 10 and 16, and an inner right side of the main body of the laser printer 1 as shown in FIG. It is comprised by the light receiving element 199b provided in the wall surface.

  The control unit 200 of the laser printer 1 is configured as a known microcomputer in which a CPU 201, a ROM 202, a RAM 203, and an I / O port 204 are connected by a bus 205. The I / O port 204 receives signals from the above-described cover sensor 198 and empty sensor 199, as well as a scanner unit 90, a drum motor 122, a developing motor 170, and a return motor 175. They are connected via circuits 211, 212, 213, and 214. In addition to the above, the I / O port 204 is connected to various known mechanisms such as an operation panel.

  FIG. 19 is a flowchart illustrating processing executed by the CPU 201 of the control unit 200 based on a program stored in the ROM 202. This process is repeatedly executed at a predetermined timing after the laser printer 1 is powered on.

  When the process is started, first in S1 (S represents a step: the same applies hereinafter), toner empty (toner is consumed and light frequently passes between the light passing portions 42d and 42d based on the detection signal of the empty sensor 199. It is determined whether or not the state has passed. That is, since the toner is agitated by the agitator 61 in the inner cylinder 63, light may pass between the light passing portions 42d and 42d even when there is sufficient toner. The passing period is longer. Therefore, in S1, it is determined whether or not the toner is empty based on the length of the period during which light passes between the light passage portions 42d and 42d. If the toner is not empty (S1: NO), the process proceeds to S2, a normal process such as forming an image on a sheet based on the input data is executed, and the process returns to S1. Until the toner becomes empty, the normal processing is continued by repeating the processing of S1 and S2.

  When the toner is empty (S1: YES), the process proceeds to S3, and the fact that the toner is empty is notified by a display on the operation panel and an alarm sound by a buzzer. In many cases, toner empty is detected during image formation on a sheet, but in subsequent S4, image formation is prohibited after the job being executed is completed.

  Further, in the subsequent S5, recovery control for driving the return motor 175 with the developing motor 170 stopped is started. By this collection control, the supply of toner from the toner cartridge 60 by the agitator 61 is stopped, and the rotation of the developing roller 41 and the supply roller 45 is also stopped. On the other hand, since the upper auger 43 and the lower auger 44 are driven, the toner in the developing cartridge 40 is conveyed left and right by the lower auger 44, and then conveyed to the center by the upper auger 43, and from the opening 42a to the toner cartridge 60. Returned to. This collection control is continued for a time sufficient to complete the collection of the toner in the developing cartridge 40 by another routine, and then automatically stopped (that is, both the developing motor 170 and the return motor 175 are stopped). The

  Therefore, in this process, after the collection control is started in S5, the process waits in S6 until the lid 4 is opened (S6: NO). That is, in response to the notification in S3, the user opens the lid 4 to replace the toner cartridge 60, but waits until the opening operation of the lid 4 is detected by the cover sensor 198.

  When the lid 4 is opened (S6: YES), the collection control is prohibited in S7, and in the subsequent S8, it is determined whether or not the collection control has already ended at that time. If not completed (S8: NO), an alarm sound is generated to notify the user that the toner cartridge 60 cannot be replaced in S9, and the lid 4 is closed by the user in accordance with the alarm sound. Until S10 waits (S10: NO). And if the cover part 4 is closed (S10: YES), a process will transfer to S5 again and the collection | recovery control will be continued.

  On the other hand, when the lid part 4 is opened after the end of the collection control (S8: YES), the process waits in S11 until the lid part 4 is closed by the user (S11: NO). Normally, the toner cartridge 60 is replaced by the user during this period. When the lid 4 is closed (S11: YES), the agitator 61 is driven by a predetermined amount in S12, and the developing cartridge 40 is filled with toner. Further, in subsequent S13, the prohibition of image formation set in S4 is canceled, and the process returns to S1 described above.

  According to the above processing, in this embodiment, when the toner is empty (S1: YES), the toner in the developing cartridge 40 is automatically collected in the toner cartridge 60 (S5). Then, after the toner cartridge 60 is replaced after the collection, the following effects are produced.

  When the non-magnetic one-component toner whose charging performance is deteriorated due to deterioration as in the laser printer 1 is frictionally charged, if the old and new toners are mixed and rubbed together, the deteriorated toner and the new toner are charged. Because of the superiority or inferiority in performance and the amount of charge is offset, both toners are not charged to the same polarity, and new toner is charged positively and deteriorated old toner is negatively charged. However, if a large amount of positively charged new toner exists in the vicinity of the developing roller 41, the new toner having a high charge amount preferentially adheres to the developing roller 41 due to the mirror image force, and the negatively charged toner is Printing fog does not occur even if it exists.

  However, when a large amount of old negatively charged toner is present in the vicinity of the developing roller 41, new toner enters the developing roller 41 preferentially to the negatively charged toner due to the mirror image force. It adheres and print fogging occurs. In a conventional laser printer, such a condition is satisfied when the toner cartridge is replaced, and print fogging may occur.

  On the other hand, in the present embodiment, in the state where the collection control is completed (S8: YES), the toner (deteriorated old toner) is low in the developing cartridge 40. Since the replacement of the toner cartridge 60 is permitted only in this state, even if the toner is supplied from the new toner cartridge 60, it is possible to prevent a small amount of new toner from being mixed with a large amount of deteriorated old toner. Therefore, in the present embodiment, it is possible to satisfactorily suppress the occurrence of printing fog.

  In this embodiment, after the toner cartridge 60 is replaced (S11: YES), the agitator 61 is driven a predetermined amount (S12), and the image formation prohibition is canceled (S13). Effects are produced.

  Even when toner empty is detected, the toner cartridge 60 may not be replaced with a new one, and the old toner cartridge 60 that has been mounted by mistake may be mounted again. In such a case, since a large amount of toner is stored in the toner cartridge 60 by the collection control, there is a possibility that erroneous detection may occur in the subsequent processing of S1. In the present embodiment, after the toner cartridge 60 is replaced (S11), the agitator 61 is driven by a predetermined amount (S12), and then the process proceeds to S1, so that erroneous detection of toner empty can be prevented. Further, by the above processing, image formation is performed after the developing cartridge 40 is filled with a sufficient amount of toner, so that it is possible to prevent image fading.

  In the above-described embodiment, the developing cartridge 40 is the developing device and the process cartridge, the agitator 61 is the supply means, the upper auger 43 and the lower auger 44 are the return means, the control unit 200 is the control means, and the empty sensor 199 is the empty sensor 199. The cover sensor 198 corresponds to the replacement time detection means and the attachment / detachment detection means. The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above-described embodiment, the replacement of the toner cartridge 60 is detected by the cover sensor 198. However, the toner sensor 60 may be detected by the cover sensor 198. Detection may be performed by providing an IC tag reader or the like.

  In the above embodiment, the replacement time is detected based on the amount of toner in the toner cartridge 60. However, the replacement time detection means in the present invention is based on, for example, the number of sheets on which an image is formed. Various forms are conceivable, such as detecting the replacement time.

  Furthermore, the present invention can be applied to various electrophotographic image forming apparatuses such as a copying machine, a facsimile machine, and a color laser printer. The electrostatic latent image carrier may be a photosensitive belt, It may be an electrostatic latent image carrier other than the body. The present invention can also be applied to an image forming apparatus provided with a so-called intermediate transfer belt. In this case, the intermediate transfer belt also corresponds to a transfer unit.

  Still further, the photosensitive cartridge 20 and the developing cartridge 40 may be fixed to the main body of the laser printer 1, and the photosensitive cartridge 20 and the developing cartridge 40 may be configured as an integral process cartridge. However, in the above-described embodiment, since the photosensitive cartridge 20 and the developing cartridge 40 are configured to be detachable individually, they can be replaced as appropriate, and the maintainability is excellent.

1 is a perspective view illustrating an appearance of a laser printer to which the present invention is applied. It is a perspective view showing the operation | movement which opens the cover part of the laser printer. It is a perspective view showing the operation | movement which pulls out the paper feed cassette of the laser printer. It is a longitudinal cross-sectional view showing the internal structure of the laser printer. It is a longitudinal cross-sectional view showing operation which takes out each cartridge of the laser printer integrally. It is a longitudinal cross-sectional view showing the movement which cuts off the toner cartridge and developing cartridge of the laser printer. FIG. 6 is a longitudinal sectional view illustrating an operation of taking out only a toner cartridge of the laser printer. It is a longitudinal cross-sectional view showing the operation | movement which takes out the developing cartridge and toner cartridge of the laser printer integrally. FIG. 6 is a left side view illustrating a configuration of a photosensitive cartridge of the laser printer. It is explanatory drawing showing the structure of the left inner wall face of the laser printer main body. FIG. 3 is a left side view illustrating a state where the toner cartridge is mounted on a developing cartridge. FIG. 4 is an explanatory diagram illustrating a configuration of a mechanism that switches connection / disconnection between the developing cartridge and the toner cartridge. FIG. 4 is a longitudinal sectional view illustrating a state where the toner cartridge is mounted on a developing cartridge. FIG. 6 is a right side view illustrating a state in which the toner cartridge is mounted on the developing cartridge. It is explanatory drawing showing the structure and operation | movement of the auger of the developing cartridge. 2 is a partially enlarged view showing a configuration of a left inner wall surface of the laser printer main body. FIG. It is the elements on larger scale showing the structure of the right inner wall face of the laser printer main body. It is a block diagram showing the structure of the control system of the laser printer. It is a flowchart showing the process performed with the control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser printer 2a ... Removable port 4 ... Cover part 7 ... Image forming part 20 ... Photoconductor cartridge 21 ... Photoconductor drum 22 ... Transfer roller 40 ... Developing cartridge 41 ... Developing roller 42 ... Supporting part 42a, 63b, 64b ... Opening Part 42d ... Light passage part 43 ... Upper auger 44 ... Lower auger 43b, 44b ... Spiral tooth 45 ... Supply roller 51, 151, 54, 154 ... Drive shaft 55 ... Partition wall 60 ... Toner cartridge 61 ... Agitator 62 ... Handle 63 ... Inner cylinder 63d ... Toner remaining amount detection window 64 ... Outer cylinder 90 ... Scanner unit 170 ... Development motor 175 ... Returning motor 198 ... Cover sensor 199 ... Empty sensor 200 ... Control unit L ... Laser light

Claims (9)

An electrostatic latent image carrier on which an electrostatic latent image is formed;
A toner cartridge in which toner used for developing the electrostatic latent image is stored;
Developing means for developing the electrostatic latent image by attaching toner accommodated in the toner cartridge to the surface of the electrostatic latent image carrier;
Transfer means for transferring the toner adhered to the surface of the electrostatic latent image carrier by the developing means to a recording medium;
A developing device in which the toner cartridge is configured to be detachable, and at least the developing means is accommodated;
An image forming apparatus comprising:
Supply means for supplying the toner contained in the toner cartridge to the developing device;
A return means operable independently of the supply means and returning the toner supplied to the developing device to the toner cartridge;
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the return means returns the toner to the toner cartridge while circulating the toner inside the developing device. The image forming apparatus according to claim 1, wherein the developing device is configured to be detachable. The image forming apparatus according to claim 1, wherein the electrostatic latent image carrier is configured to be detachable. 5. The image forming apparatus according to claim 1, wherein the developing unit stops operating when the return unit operates while the supply unit is stopped. A replacement time detecting means for detecting a replacement time of the toner cartridge;
Control means for executing recovery control for operating the return means while the supply means is stopped when the replacement time detection means detects the replacement time;
The image forming apparatus according to claim 1, further comprising: An attachment / detachment detecting means for detecting attachment / detachment of the toner cartridge or opening / closing of an attachment / detachment opening of the toner cartridge;
The replacement time detection means detects the replacement time based on the amount of toner contained in the toner cartridge;
After the control means executes the collection control, when the attachment / detachment detection means detects attachment / detachment of the toner cartridge or opening / closing of the attachment / detachment opening of the toner cartridge, the control means operates the supply means by a predetermined amount. 7. The image forming apparatus according to claim 6, wherein a detection result of the replacement time detection unit is referred to later. The image forming apparatus according to claim 1, wherein the toner is a non-magnetic one-component toner. A toner cartridge in which toner used for developing an electrostatic latent image formed on the surface of the electrostatic latent image carrier is accommodated is detachable.
At least developing means for developing the electrostatic latent image by attaching the toner contained in the toner cartridge to the surface of the electrostatic latent image carrier;
A process cartridge detachable from the image forming apparatus,
A return means that is operable independently of the toner supply operation from the toner cartridge, and returns the toner in the process cartridge toward the toner cartridge;
A process cartridge comprising: