JP2007057865A - Image forming apparatus and process cartridge mounted on the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and a process cartridge which allow an image of high quality to be formed while preventing toner scattering even when replacing an image carrier of which the durable lifetime has come to an end. <P>SOLUTION: With respect to the image forming apparatus A including developer agitating means 1g and 1h, a developer carrier 1e, a toner carrier 1d, and an image carrier 1a, the image carrier 1a and the toner carrier 1d are integrally stored as a process cartridge 6, and the developer carrier 1e and the developer agitating means 1g and 1h are stored in a storage part 1q, and the process cartridge 6 is attachable to and detachable from an image forming apparatus main body and is linked with the storage part 1q when being attached to the image forming apparatus main body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that supplies a developer to an electrostatic latent image formed on an image carrier corresponding to a recorded image and visualizes the image, and a process cartridge provided in the image forming apparatus.

  2. Description of the Related Art Conventionally, for example, an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile machine includes a developer agitating unit that agitates a developer in which toner and a magnetic carrier (two-component developer) are mixed and conveys the developer. , A developer carrier that carries the developer supplied from the developer agitating means on the outer circumferential surface by the magnetic force of a plurality of built-in magnets, a developer carrier, and a part of the outer circumferential surface of the developer carrier. Of the developer carried by the developer carrier, and supplied only with toner (one-component developer) and transported while carrying the toner, and the toner carrier and each other A part of the outer peripheral surface of the toner is provided so as to face each other with a predetermined gap, and toner is supplied from the toner carrier to the outer peripheral surface on which the electrostatic latent image corresponding to the image to be recorded is formed to reveal the electrostatic latent image. For imaging There is provided with a bearing member (e.g., see Patent Document 1).

  In this type of image forming apparatus, the toner is not directly supplied to the electrostatic latent image formed on the image carrier from the two-component developer of the carrier carried on the developer carrier and the toner charged and adhered thereto, Only the toner is once carried on the toner carrying member and then supplied to the electrostatic latent image on the image carrying member. Thus, the image forming apparatus uses both the so-called two-component developing method and the one-component developing method.

In the image forming apparatus configured as described above, there is a disadvantage of the one-component developing method, that is, when the toner is supplied to the toner carrier, for example, it is not necessary to slide the toner supply roller, and the toner deterioration accompanying this is not necessary. In addition, the wear of the toner carrier can be lost. Further, the disadvantage of the two-component development method, that is, when supplying toner to the image carrier, the developer carried in a brush shape on the outer peripheral surface of the developer carrier comes into contact with the image carrier and the toner image is uneven. Problems such as occurrence or supply of the carrier together with the toner to the image carrier can be solved. For this reason, in the above-described image forming apparatus, the toner is properly charged by the advantage of the one-component developing method that can reliably supply only the toner to the electrostatic latent image and obtain a high-quality formed image, and friction with the carrier. In addition, since the toner can be transported while being charged and attached to a carrier, it is possible to have the advantages of the two-component development system that is capable of high-speed processing and is excellent in durability.
JP 2002-174951 A

  However, the above-described image forming apparatus has excellent durability, which is an advantage of the two-component development method, but has a problem that the number of members increases, resulting in an increase in cost. In particular, an image carrier on which an electrostatic latent image is formed needs to be replaced when an image of about 10,000 prints is formed, for example, for developing a recorded image including the image carrier. In the case where the developing means are integrated, the members having different endurance numbers reaching the end of their lives are exchanged in a lump, resulting in a problem that the cost is further increased.

  On the other hand, there is an image forming apparatus in which the image carrier and other members are formed separately, and only the image carrier that has reached the endurance life is replaced by replacing only the image carrier with a cartridge. However, even in such a configuration, in general, toner is often deposited between the image carrier and the toner carrier as image formation is performed, and this deposition occurs when the image carrier is removed. As a result, the toner is scattered to other parts of the image forming apparatus, and there is a problem in that the image is smeared due to toner drops. Further, there are cases where toner is scattered on the hands and clothes of the operator who performs the replacement to cause dirt.

  Furthermore, the gap accuracy between the image carrier and the toner carrier is required to be within an error range of, for example, about 100 to 200 μm in order to ensure the stability of the formed image. In the case of replacing the image carrier, there is a problem that the image quality of the formed image changes every time the cartridge-formed image carrier is replaced.

  SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides an image forming apparatus and a process cartridge that enable high-quality image formation while preventing toner scattering even when replacing an image carrier that has reached the end of its useful life. It is an object.

  In order to achieve the above object, the present invention provides the following means.

  The image forming apparatus according to the present invention includes a developer agitating unit that agitates and conveys a developer composed of toner and a carrier to which the toner is charged, and the developer supplied from the developer agitating unit magnetically. A developer carrying member that is carried while being carried, a toner carrying member that is carried while carrying the toner supplied from the developer carrying member, and an electrostatic latent image of a recorded image are formed from the toner carrying member. An image forming apparatus comprising an image carrier that is supplied with the toner and visualizes the electrostatic latent image, wherein the image carrier and the toner carrier are integrally accommodated as a process cartridge, and the developer The carrier and the developer agitating means are accommodated in an accommodating portion in the image forming apparatus main body, and the process cartridge is detachable from the image forming apparatus main body and attached to the image forming apparatus main body. And wherein the coupling is by that in the accommodation portion.

  In the image forming apparatus according to the present invention, when the process cartridge that integrally stores the image carrier and the toner carrier is detachable from the image forming apparatus main body and is attached to the image forming apparatus main body, the developer carrying is performed. When the image carrier reaches the end of its service life, the image carrier and the toner carrier can be removed and replaced at once without being separated by being connected to a housing portion that houses the body and the developer agitating means. Is possible.

  The process cartridge of the present invention is a process cartridge that can be attached to and detached from the main body of the image forming apparatus, and receives the toner from a developer carrier that carries a developer composed of toner and a carrier to which the toner is charged and attached. The image forming apparatus comprising: a carrier; and an image carrier on which an electrostatic latent image of a recorded image is formed and the toner is supplied from the toner carrier to visualize the electrostatic latent image. A developer agitating unit that is provided in the image forming apparatus main body and conveys the developer while being agitated, and is magnetically carrying the developer supplied from the developer agitating unit. It is connected with the accommodating part which accommodated the developer carrier to convey.

  In the process cartridge according to the present invention, an image carrier and a toner carrier are formed into a cartridge, so that the gap between the image carrier and the toner carrier is always maintained constant, It can be installed.

  According to the image forming apparatus and the process cartridge including the image forming apparatus according to the present invention, the image carrier and the toner carrier that are integrated as a process cartridge can be exchanged together. The gap between the image carrier and the toner carrier that directly affects the toner carrier is required to maintain a constant gap, and the gap accuracy between the toner carrier and the developer carrier has little influence on the image quality of the formed image. Since the image is separated at a part, it is possible to prevent the formed image from changing with the replacement of the process cartridge. Further, when the process cartridge is replaced, it is possible to prevent the toner deposited between the image carrier and the toner carrier from being scattered along with the removal of the process cartridge, and to prevent image smearing due to toner dropping. This makes it possible to always form a high quality image.

  Further, even when the image carrier and the toner carrier are made into a cartridge and the toner carrier is exchanged together with the image carrier, the toner carrier is a simple and relatively inexpensive member. Compared to the case where only a conventional image carrier is used as a process cartridge, the increase in product cost is slight. Considering the cost of cleaning the image forming apparatus due to the scattering of toner, the total cost can be reduced.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention and a process cartridge included in the image forming apparatus will be described with reference to FIGS. 1 to 5. The present embodiment relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a process cartridge, and forms an image using a developer in which a nonmagnetic toner and a magnetic carrier are mixed. The present invention relates to an image forming apparatus and a process cartridge.

  As shown in FIG. 1, the image forming apparatus A according to the present embodiment is a tandem image forming apparatus A, which is provided for each of magenta, yellow, cyan, and black according to the image signal of the recorded image. A plurality of developing means 1 for forming toner images of respective colors, an intermediate transfer body 2 having a transfer belt 2a to which toner images formed by the respective developing means 1 are sequentially transferred, and a recording body S such as a sheet are accommodated. Main components are a recording medium conveying means 3 that conveys the recording medium S while taking out the recording medium S from the cassette 3a, and a fixing means 4 that fixes the toner image transferred from the intermediate transfer body 2 to the recording medium S to the recording medium S. It is said that. Here, in the present embodiment, the image forming apparatus main body B is configured by combining the above-described components.

  As shown in FIGS. 1 to 3, the plurality of developing means 1 provided for each color are each formed in a substantially cylindrical shape, and are provided with a photosensitive drum (image carrier) provided to be rotatable around the axis O <b> 1. 1a, a charger 1b for uniformly charging the outer peripheral surface of the photosensitive drum 1a to a negative charge, and an outer peripheral surface of the photosensitive drum 1a provided upstream of the charger 1b in the rotation direction T1 of the photosensitive drum 1a. A cleaning device 1c that removes and cleans the toner adhering to the toner, and a negatively charged toner carried on the outer peripheral surface is supplied to an electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1a by a light running device 5 described later. A toner carrier 1d for forming a toner image on the photosensitive drum 1a, and a developer containing a fixed magnet body and a mixture of toner and a magnetic carrier are conveyed while being carried magnetically on the outer peripheral surface. Developer for supplying toner to body 1d A holding body 1e, a regulating bar 1f for forming a thin layer of the developer while regulating the amount of the developer carried by the developer carrying body 1e, and conveying the developer while stirring the developer 1e. And a pair of developer agitating means 1g and 1h. In addition, the outer periphery of the uniformly charged photosensitive drum 1a is scanned and exposed while irradiating a laser beam, thereby forming an electrostatic latent image on the photosensitive drum 1a according to the image signal of the recorded image. The apparatus 5 is provided in the image forming apparatus A separately from the developing unit 1.

  In the developing unit 1 configured as described above, the charger 1b, the cleaning device 1c, and the toner carrier 1d are disposed on the outer periphery in the radial direction of the photosensitive drum 1a along the outer peripheral surface, and the charger 1b is used as a reference. Are arranged on the downstream side in the rotation direction T1 of the photosensitive drum 1a in order. The photosensitive drum 1a and the toner carrier 1d are arranged close to each other so that their outer peripheral surfaces face each other with a predetermined gap within an error range of, for example, 100 to 200 μm. On the other hand, the photosensitive drum 1a, the charger 1b, the cleaning device 1c, and the toner carrier 1d are integrated into the process cartridge 6 while being housed in the first housing 1p. Further, in the process cartridge 6, the outer peripheral surface in the circumferential direction located between the cleaning device 1 c of the photosensitive drum 1 a and the toner carrier 1 d is exposed to the first casing 1 p while being exposed to the upper outside of the process cartridge 6. A first opening 1 i is provided so as to face, and a second opening 1 j is provided so that the lower outer peripheral surface of the toner carrier 1 d faces the lower outer side. Further, an engaging portion 1k that protrudes downward and outward is provided in a portion of the first housing 1p that forms the second opening 1j. The engaging portion 1k is a second housing (accommodating) described later. Part) is engaged with the part forming the opening part 11 of 1q to hold each other integrally. Here, the first housing 1p is also provided with an opening (not shown) for irradiating the photosensitive drum 1 with the laser light emitted from the light traveling device 5.

  On the other hand, the developer carrier 1e, the regulating bar 1f, and the pair of developer agitating means 1g and 1h are arranged in the second casing (accommodating) while arranging the pair of developer transport means 1g and 1h below the developer carrier 1e. Part) It is stored in 1q. The accommodating portion 1q is provided with an opening 1l that opens so that the outer peripheral surface that is rotated about the axis O2 of the developer carrier 1e and is sequentially positioned upward faces the upper outside. Further, in the accommodating portion 1q, a developer in which toner and a carrier are mixed is accommodated in a lower portion where the pair of developer conveying means 1g and 1h are disposed. Incidentally, toner storage tanks 8m, 8y, 8c, and 8b for storing toner for each color provided in the image forming apparatus A separately from the developing unit 1 are provided in a plurality of storage units of the plurality of developing units 1, respectively. 1q is connected and supplied.

  The process cartridge 6 and the housing portion 1q are integrated in a separable manner by engaging the engaging portion 1k of the process cartridge 6 with the opening 11 of the housing portion 1q, that is, the toner carrier 1d of the process cartridge 6 is integrated. Below each other, the developer carrying bodies 1e of the accommodating portions 1q are connected to each other. Further, in the state where the process cartridge 6 and the container 1q are connected as described above, the outer peripheral surfaces of the toner carrier 1d and the developer carrier 1e which are close to each other and are opposed to each other hold a predetermined gap. Yes.

  Incidentally, for example, an operation portion such as a lever (not shown) for raising and lowering the accommodating portion 1q and an intermediate transfer member 2 described later in detail is provided in the image forming apparatus A, and the developing means 1 configured as described above. By operating this operation section, it is possible to separate the process cartridge 6 and the accommodating section 1q as shown in FIG. Further, the separated process cartridge 6 is slidable on a rail (not shown) extended along the axis O1 of the photosensitive drum 1a in the image forming apparatus A, for example, and can be pulled out from the image forming apparatus main body B. It is said.

  On the other hand, the developing means 1 is provided with a bias voltage applying means 10 for applying a bias voltage between the toner carrier 1d and the developer carrier 1e as shown in FIG. The bias voltage applying means 10 includes a first voltage applying means 10a connected to the toner carrier 1d and a second voltage applying means 10b connected to the developer carrier 1e, and each has a transformer power supply 10c. It is configured. Here, the transformer power supply 10c of the first voltage application means 10a is a superimposed power supply of direct current (DC) and alternating current (AC). For example, the potential of the toner carrier 1d is DC-300V + AC1000V (voltage between peaks) / 3 kHz. Is done. Further, the transformer power supply 10c of the second voltage applying means 10b is a DC power supply. For example, when a toner, which will be described later in detail, is allowed to fly from the developer carrier 1e to the toner carrier 1d, the developer carrier. The potential of 1e is set to DC-600V. Conversely, when the toner is caused to fly from the toner carrier 1d toward the developer carrier 1e, the potential of the developer carrier 1e is set to DC0V.

  Further, as shown in FIG. 4, the toner carrier 1d and the developer carrier 1e are provided with toner carrier driving means 1m such as a motor for driving the toner carrier 1d and the developer carrier 1e around the axes O2 and O3, respectively. Means 1n are provided. The developing unit 1 controls the toner carrier driving unit 1m and the developer carrier driving unit 1n, and the first and second voltage applying units 10a and 10b, and the toner carrier 1d and the developer are controlled. A control means 11 is provided for changing the relative magnitude of each potential of the carrier 1e. In addition to this, the developing means 1 is provided with other driving means (not shown) for rotating the photosensitive drum 1a and the pair of developer agitating means 1g and 1h around the axis, respectively, in this embodiment. These descriptions are omitted.

  As shown in FIG. 1, each developing unit 1 configured as described above is a photosensitive member that faces the outer periphery of the transfer belt 2 a of the intermediate transfer member 2, which will be described in detail later, from the first opening 1 i. The outer peripheral surface of the body drum 1a is disposed along the transfer belt 2a while contacting. At this time, the developing means 1 for forming magenta, yellow, cyan, and black toner images are arranged in this order from the most upstream side with reference to the transfer direction (arrow direction) of the transfer belt 2a. Yes.

  The intermediate transfer body 2 is provided on the inner peripheral side of the transfer belt 2a, an endless transfer belt 2a that is circulated and moved by a driving roller 2b, a tension roller 2c, and support rollers 2d and 2e arranged on the inner peripheral side thereof. The plurality of primary transfer rollers 2f that press the transfer belt 2a against the outer peripheral surface of the photosensitive drum 1a of each developing means 1 disposed on the outer peripheral side of the transfer belt 2a, and the transfer direction (arrow direction) of the transfer belt 2a It is provided so as to face the support roller 2e disposed on the downstream side in the transfer direction with respect to the developing means 1 for forming a black toner image provided on the most downstream side of the transfer belt 2a and sandwich the transfer belt 2a with the support roller 2e. The secondary transfer roller 2g and the outside of the transfer belt 2a on the upstream side in the transfer direction with respect to the developing means 1 for forming a magenta toner image provided on the most upstream side in the transfer direction. Provided on the side, and a belt cleaning device 2h for removing toner attached to the transfer belt 2a.

  The recording medium conveying means 3 includes a plurality of conveying rollers 3b that rotate synchronously, conveys the recording medium S while taking it out of the cassette 3a, and between the secondary transfer roller 2g and the transfer belt 2a. It is for supply. Further, the recording medium S carrying the toner image by the secondary transfer roller 2g is conveyed to a fixing device 4 provided downstream in the recording medium S conveyance direction, which will be described later, and thereby the recording medium S on which the toner image is melted and fixed. Is further conveyed and discharged to the outside of the image forming apparatus main body B.

  The fixing device 4 includes a heating roller 4a and a pressure roller 4b that are provided so that their outer peripheral surfaces are in pressure contact with each other. The heating roller 4a is formed in a substantially cylindrical shape and is rotatable about a shaft. For example, the heating roller 4a is configured by winding a heat-resistant elastic layer such as silicon rubber around a metal core, and includes a heat source such as a halogen lamp therein. It is supposed to be. On the other hand, the pressure roller 4b is formed in a substantially cylindrical shape capable of rotating the shaft, and is configured, for example, by winding a heat-resistant elastic layer such as silicon rubber around a metal core. Such a fixing device 4 presses the toner image carried by the recording material S fed between the heating roller 4a and the pressure roller 4b while heating and melting the recording material S, and applies the toner image to the recording material S. Can be melt-fixed.

  Next, the operation of the image forming apparatus A having the above configuration will be described. Here, description will be made on the assumption that the control means 11 for controlling the developing means 1 also performs control other than the developing means 1.

  First, the process cartridge 6 and the accommodating portion 1q of the developing means 1 are held together by engaging the engaging portion 1k and the opening portion 11. When the image forming apparatus A in this state is operated, the acquired image signal of the recorded image is sent to the control unit 11 and an operation command is issued from the control unit 11 to the developing unit 1. Upon receiving the instruction, the developing means 1 uniformly charges the outer peripheral surface of the photosensitive drum 1a to a negative charge by the charger 1b, and the light traveling device 5 emits laser light in accordance with the image signal of the recorded image. An electrostatic latent image is formed. Further, when the image forming apparatus A is operated, the developer agitating units 1g and 1h that have received a command from the control unit 11 and the driving units 1m and 1n of the developer carrier 1e and the toner carrier 1d are driven. The developer in the container 1q is stirred and the developer is supplied toward the outer peripheral surface of the developer carrier 1e. The developer carrying member 1e magnetically carries the developer while rotating and conveys the developer to the opening 11 side of the housing portion 1q facing the toner carrying member 1d. At this time, the developer carried between the regulating rod 1f and the outer peripheral surface of the developer carrier 1e passes, so that the amount thereof is regulated and the developer on the developer carrier 1e is formed into a thin layer.

  At this time, as shown in FIG. 4, the first and second voltage applying means 10a and 10b provided on the toner carrier 1d and the developer carrier 1e are controlled by the control means 11, and the developer carrier 1e The potential Vp of the outer peripheral surface is, for example, DC-600V, and the potential Vt of the outer peripheral surface of the toner carrier 1d is larger than the potential Vp of the outer peripheral surface of the developer carrier 1e, for example, DC-300V + AC1000V (peak-to-peak voltage) / 3 Hz. It is said that. For this reason, in the developer carried on the developer carrier 1e and conveyed toward the opening 11l, only the negatively charged toner attached to the carrier is rotated on the axis while the positively charged carrier is held on the developer carrier 1e. It is carried by flying on the outer peripheral surface of the toner carrier 1d. Then, the toner carried on the toner carrying member 1d is conveyed to the photosensitive drum 1a side, and this toner is supplied to the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1a to form a toner image. Incidentally, at this time, the potential of the outer peripheral surface of the portion of the photosensitive drum 1a where the electrostatic latent image is formed is, for example, 0 to −50V, and the potential of the outer peripheral surface other than the electrostatic latent image is, for example, −500V. Has been.

  Such a toner image is formed on the photoconductive drum 1a of each developing unit 1 provided for each color, and the transfer belt 2a of the intermediate transfer unit 2 receives the command from the control unit 11 of the driving roller 2b. It is transferred in the transfer direction as it is driven. At this time, the transfer belt 2a is first pressed against the photosensitive drum 1a of the magenta developing means 1 provided on the most upstream side in the transfer direction by the corresponding primary transfer roller 2f, and the magenta toner image is transferred. Transfer is started on the outer peripheral surface of the transfer belt 2a. Then, the transfer belt 2a is sequentially conveyed, and each color toner image is superimposed on the toner image transferred by the developing means 1 on the upstream side in the conveyance direction, that is, magenta, yellow, cyan, and black. The toner images are sequentially superimposed, and finally, a color toner image in which the toner images of all colors are superimposed on the outer peripheral surface of the transfer belt 2a is formed. Then, the recording medium conveying means 3 that receives the operation command from the control means 11 conveys the recording medium S between the secondary transfer roller 2g and the transfer belt 2a, and the color toner image carried on the recording medium S by the transfer belt 2a. Is transcribed. The recording material S subjected to the secondary transfer is conveyed toward the fixing device 4 and passes between the heating roller 4a and the pressure roller 4b while applying heat and pressure, and the carried color toner image is melted. It will be fixed. Thus, the recording medium S on which the recording image is formed is further conveyed and discharged to the outside of the image forming apparatus main body B.

  Here, in the present embodiment, when the developing unit 1 finishes the image formation of the toner image of the image to be recorded, the developing unit 1 is connected to the developer carrier 1e based on the command of the control unit 11 that detects the end of the image formation. Further, the supply voltage of the second voltage applying means 10b is changed, and the potential Vp of the outer peripheral surface of the developer carrier 1e is set to, for example, DC0V, which is higher than the potential Vt of the toner carrier 1d. As a result, the toner is supplied from the developer carrier 1e toward the toner carrier 1d during the developing operation (from the container 1q toward the process cartridge 6), and remains in the state of being carried on the toner carrier 1d at the end of image formation. On the contrary, the toner that is present is returned from the toner carrier 1d toward the developer carrier 1e (from the process cartridge 6 toward the container 1q). Incidentally, at this stage, the potential of the outer peripheral surface 1a of the photosensitive drum 1a is uniformly set to, for example, −500V.

  FIG. 5 is a timing chart collectively showing the operating state of the developing unit 1 operating as described above over time. In this figure, drive means represent toner carrier drive means 1m and developer carrier drive means 1n, and in FIG. 5 (a) corresponding thereto, the drive means 1m, 1n operate in the vertical axis direction. It has been shown. FIG. 5B, which is referred to as image formation, shows an operating state of the developing unit 1 for forming a toner image on the photosensitive drum 1a, and shows that the vertical axis is operating. ing. Further, FIG. 5C shows the difference (applied voltage Vt−) of the potential Vp of the developer carrier 1e with respect to the potential Vt (DC component) of the toner carrier 1d by the first voltage application means 10a and the second voltage application means 10b. Vp). Here, the horizontal axis indicates the elapsed time, and this figure shows a state in which the developing unit 1 is operated so as to continuously form three toner images.

  As shown in FIG. 5, in the image forming apparatus A of the present embodiment, the entire developing unit 1 such as a driving unit starts its operation from time t1 when the operation unit 11 issues an operation command to the developing unit 1, and the time t1 The first toner image is formed from time to time t2. At this time, the potential difference between the toner carrier 1d and the developer carrier 1e is Vt−Vp> 0, and the toner charged to a negative charge flies from the developer carrier 1e to the toner carrier 1d and becomes toner. It is supplied to the carrier 1d. Further, the formation of the second toner image is started from time t3, and the formation of this toner image is completed at time t4. Then, after the image formation of the third toner image is completed at time t6, the potential difference between the toner carrier 1d and the developer carrier 1e is reversed so that Vt−Vp <0. The toner supplied from the portion 1q toward the process cartridge 6 and carried on the toner carrier 1d is returned from the process cartridge 6 toward the storage portion 1q to be carried on the developer carrier 1e. . In this state, after the toner carrier 1d is rotated once or more, driving of the driving units 1m and 1n is stopped, and voltage supply by the bias voltage applying unit 10 is stopped.

  On the other hand, in the image forming apparatus A in which the developing unit 1 operates as described above, each member such as the photosensitive drum 1a and the developing carrier 1e constituting the developing unit 1 has a different durable number that reaches the end of its life. For example, in the case of the photosensitive drum 1a having a diameter of 30 mm or less, it is necessary to replace the recording body after about 10,000 prints of the recording body. In some conventional image forming apparatuses, the photosensitive drum 1a is separable from other constituent members of the developing unit 1 and is a process cartridge that is detachable from the main body of the image forming apparatus. However, in this conventional image forming apparatus, the toner accumulated between the photosensitive drum 1a and the toner carrier 1d accompanying the image formation is removed when the photosensitive drum 1a as a process cartridge is removed from the image forming apparatus main body. There is a problem in that it scatters and adheres to the hands and clothes of the operator or contaminates the periphery of the developing means 1.

  In addition, the photosensitive drum 1a and the toner carrier 1d need to be installed with a high accuracy within an error range of, for example, 100 to 200 μm between the outer peripheral surfaces of the photosensitive drum 1a and the photosensitive drum while ensuring such a gap accuracy. It is very difficult for a general user to replace only 1a, and there is a problem that the image quality formed on the recording medium S changes each time the photosensitive drum 1a as a process cartridge is replaced. It was.

  On the other hand, in the present embodiment, the photosensitive drum 1a and the toner carrier 1d of the developing unit 1 are integrally accommodated as a process cartridge 6, and the process cartridge 6 can be separated while being integral with the accommodating portion 1q. Has been. The developing unit 1 configured as described above has the process cartridge 6 and the container 1q when the lever (operation unit) provided in the image forming apparatus is in the posture for image formation (toner image formation). They are held together and locked.

  When the process cartridge 6 integrated with the container 1q and attached to the image forming apparatus main body B in this way is removed from the image forming apparatus main body B and replaced, the lever is operated as shown in FIG. The housing portion 1q is lowered relative to the process cartridge 6 by about 1 mm, for example, and the engagement state between the engaging portion 1k of the first housing 1p of the process cartridge 6 and the opening portion 11 of the housing portion 1q is released. The At the same time, the intermediate transfer member 2 relatively rises, and the contact state between the photosensitive drum 1a of the process cartridge 6 and the transfer belt 2a is released. As a result, the developing means 1 is separated at the gap between the toner carrier 1d and the developer carrier 1e, and the process cartridge 6 is brought into a free state. Further, the free process cartridge 6 is pulled out along a rail (not shown) provided in the image forming apparatus main body B, for example, by pulling a lever outward of the image forming apparatus main body B. As a result, it is possible to replace the process cartridge 6 provided with the photosensitive drum 1a requiring replacement with a process cartridge 6 provided with a new photosensitive drum 1a. Further, by performing the above operations in reverse order, a new process cartridge 6 can be attached to the image forming apparatus main body B and connected to the accommodating portion 1q.

  The process cartridge 6 of this embodiment mounted on the image forming apparatus main body B in this way is a cartridge formed by integrally housing the photosensitive drum 1a and the toner carrier 1d, and the photosensitive drum 1a that requires high accuracy. And the toner carrier 1d are formed with a predetermined accuracy in advance. Therefore, the quality change of the formed image that has occurred every time the photosensitive drum 1a is replaced is inevitably generated, and stable image formation is possible even when the process cartridge 6 is replaced.

  In addition to this, as described above with reference to FIG. 5, the bias voltage applying means 10 is controlled by the control means 11 before the process cartridge 6 is replaced, and is supplied from the accommodating portion 1q toward the process cartridge 6. The toner carried on the toner carrying member 1d is returned from the process cartridge 6 toward the container 1q and carried on the developer carrying member 1e when the image forming operation ends. For this reason, when the process cartridge 6 is separated from the container 1q and removed from the image forming apparatus main body B, most of the toner in the process cartridge 6 is collected in the container 1q. . Therefore, toner does not scatter from the second opening 1j that opens downward from the process cartridge 6. Further, even when an impact or the like is applied in accordance with the separation of the process cartridge 6 and the accommodating portion 1q and a small amount of toner remaining in the process cartridge 6 falls downward through the second opening 1j, the process cartridge Since 6 is arranged above the accommodating part 1q, it will fall into the accommodating part 1q through the opening part 11 of the accommodating part 1q located just under it. Therefore, the process cartridge 6 is surely replaced without causing toner scattering.

  Therefore, in the image forming apparatus A and the process cartridge 6 having the above-described configuration, the photosensitive drum 1a and the toner carrier 1d are integrally accommodated as the process cartridge 6, so that the photosensitive drum 1a is replaced. In addition, the gap between the photosensitive drum 1a and the toner carrier 1d can be surely maintained and replaced with high accuracy, so that high-quality image formation can always be performed.

  In addition, a housing portion 1q is provided below the process cartridge 6 to be integrated, and a bias voltage applying means 10 for inverting the magnitudes of the potentials of the toner carrier 1d and the developer carrier 1e by the controller 11 is provided. Thus, toner scattering due to the replacement of the process cartridge 6 can be reliably prevented, and it is possible to prevent the toner from adhering to the formed image and the operator's hand and clothes.

  Further, in the case of the process cartridge 6 in which the toner carrier 1d is integrally accommodated in addition to the photosensitive drum 1a, the toner carrier 1d is a relatively simple member having a relatively simple structure. It is possible to reduce the cost as much as or less than that of a process cartridge using only the photosensitive drum 1a. That is, by using the process cartridge 6 of the present embodiment, image change and toner scattering associated with replacement can be prevented, and thereby, the useless recording medium S can be lost and the cleaning work associated with toner scattering can be lost. . In particular, it is not necessary to request a specialist (serviceman) for replacement of the photosensitive drum 1a and maintenance of toner scattering, which are required to be installed with high accuracy. Reduction can be achieved, and the total cost can be reduced.

  The embodiments of the image forming apparatus and the process cartridge according to the present invention have been described above. However, the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in the above-described embodiment, the description has been given on the assumption that the accommodating portion 1q is disposed below the process cartridge 6. However, the installation position may not be limited below the process cartridge 6. In the present embodiment, at the end of the image formation of the developing unit 1, a voltage is applied so that the toner flies from the toner carrier 1d toward the developer carrier 1e. There is no need to limit at the end of image formation. For example, it may be performed immediately before the process cartridge 6 is separated from the accommodating portion 1q. Further, the process cartridge 6 is provided with the photosensitive drum 1a, the toner carrier 1d, the charger 1b, and the cleaning device 1c, but at least the photosensitive drum 1a and the toner carrier 1d are formed into a cartridge. The charger 1b and the cleaning device 1c may be provided separately from the process cartridge 6.

  Further, the control means 11 of the present embodiment is not limited to the one that controls only the individual developing means 1 as shown in FIG. 4, and controls the plurality of developing means 1 together or the entire image forming apparatus A. May be controlled.

  Further, in the present embodiment, the engaging portion 1k is provided in the first housing 1p of the process cartridge 6, and the engaging portion 1k is engaged with the opening 11 of the accommodating portion 1q, so that the process cartridge 6 (first cartridge) Although the housing 1p) and the housing portion (second housing) 1q are connected, for example, an engaging portion may be formed on the second housing 1q to connect each other. Neither the means nor the means need to be limited.

  Furthermore, in the present embodiment, the image forming apparatus A is configured to form a color toner image by superimposing the toner images of the respective colors on the transfer belt 2a of the intermediate transfer body 2 and to carry the color toner image on the recording body S. In the present invention, the recording medium S is fed between the photosensitive drum 1a and the transfer belt 2a of each developing means 1 provided along the transfer belt 2a to form an image. The present invention may be applied to an image forming apparatus. In this embodiment, the image forming apparatus A that uses four colors of magenta, cyan, yellow, and black is described to form a full-color image. However, three colors of magenta, cyan, and yellow are used. The present invention may be applied to an image forming apparatus that forms a full-color image or an image forming apparatus that forms a monochrome image using only black.

1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a developing unit provided in the image forming apparatus of FIG. 1. FIG. 3 is a diagram illustrating a state where a process cartridge and a housing portion of the developing unit in FIG. 2 are separated. FIG. 3 is a block diagram of a control system of the developing unit shown in FIG. 2. 3 is a timing chart showing an operation of the developing unit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing means 1a Photosensitive drum (image carrier)
1b Charger 1c Cleaning device 1d Toner carrier 1e Developer carrier 1g Developer agitation means 1h Developer agitation means 1k Engagement portion 1p First housing 1q Storage portion (second housing)
2 Intermediate transfer member 2a Transfer belt 3 Recording member conveying means 4 Fixing device 5 Light running device 6 Process cartridge 10 Bias voltage applying means 11 Control means A Image forming apparatus B Image forming apparatus main body

Claims (5)

Developer agitating means for agitating and conveying a developer comprising toner and a carrier to which the toner is charged; and developer carrying for carrying the developer supplied from the developer agitating means while magnetically carrying the developer An electrostatic latent image of the image to be recorded is formed, and the toner is supplied from the toner carrier to form the static image. In an image forming apparatus provided with an image carrier on which an electrostatic latent image is visualized,
The image carrier and the toner carrier are integrally accommodated as a process cartridge, the developer carrier and the developer agitating unit are accommodated in an accommodating portion in an image forming apparatus main body, and the process cartridge is An image forming apparatus, wherein the image forming apparatus is attachable to and detachable from the main body of the image forming apparatus and is connected to the housing portion when the main body is attached to the main body of the image forming apparatus.   The image forming apparatus according to claim 1, wherein when the process cartridge is attached to the main body of the image forming apparatus, the developer carrier is disposed below the toner carrier.   Bias voltage applying means for applying a bias voltage between the toner carrier and the developer carrier; and control means for making the relative magnitudes of the potentials of the developer carrier and the toner carrier variable. The image forming apparatus according to claim 1, further comprising: A process cartridge that can be attached to and detached from the image forming apparatus main body,
A toner carrier for receiving the toner from a developer carrier carrying a developer composed of toner and a carrier to which the toner is charged; and an electrostatic latent image of a recorded image is formed from the toner carrier. And an image carrier that visualizes the electrostatic latent image, and is mounted on the image forming apparatus main body while stirring the developer. A process cartridge that is connected to an accommodating portion that accommodates a developer agitating unit that conveys and a developer carrying member that conveys the developer supplied from the developer agitating unit while magnetically carrying the developer. . An engagement portion is provided for connecting to the housing portion while arranging the developer carrier below the toner carrier when mounted on the image forming apparatus main body. 5. The process cartridge according to 4.

Images