JP2016014812A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a developer from overflowing when removing a developing device 4 from an apparatus body.SOLUTION: A stirring chamber 44 is connected to a discharge path 48 having a discharge port 47. These stirring chamber 44 and discharge path 48 are provided with a second stirring and conveyance screw 46 having a main conveyance screw part 46a, return screw part 46b, and discharge screw part 46c as a one body. On removal of the developing device 4 from an apparatus body, the second stirring and conveyance screw 46 is driven before the developing device 4 is removed from the apparatus body, so as to rotate the discharge screw part 46c to discharge the developer inside the discharge path 48 from the discharge port 47. With this configuration, a developer can be suppressed from dropping when the developing device 4 is removed.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having a plurality of these functions, and more particularly to a configuration in which a developing device can be detached from the apparatus main body.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a two-component developing method in which a nonmagnetic toner and a magnetic carrier are mixed and used as a developer has been widely used. In the two-component development method, the developer is deteriorated by long-term use, particularly the carrier is deteriorated. Therefore, the operation of changing the developer is performed with the long-term use of the image forming apparatus. For example, the developer containing the toner consumed by the developing operation of the developing device is replenished to the developing container, and excess developer in the developing container is discharged to a waste developer containing container disposed outside the developing container. Has been proposed (Patent Document 1).

JP 2010-256701 A

  In the case of the conventional configuration as described above, the mechanism for discharging the surplus developer is provided with a simple shutter at the developer outlet of the developer container so that the surplus developer is discharged to the waste developer container by gravity. Often discharged downward in the direction. Therefore, when the developing device is removed from the apparatus main body for maintenance or replacement of the developing device, there is a possibility that the developer accumulated in the vicinity of the developer discharge port may spill. For example, the developer may spill out from the vicinity of the shutter of the developer discharge port into the apparatus main body or in the vicinity of the apparatus main body due to vibration of the removing operation of the developing apparatus or tilting of the developing apparatus at the time of removal. Note that even if the developer discharge port is open in a horizontal direction other than the direction below the gravitational direction, if the developer accumulates near the developer discharge port, the developer may be spilled when the developing device is removed. There is sex.

  In view of such circumstances, an object of the present invention is to prevent the developer from spilling when the developing device is removed from the apparatus main body.

  The present invention provides an apparatus main body, a developing container which is detachable from the apparatus main body and has a discharge port for discharging the developer, a developing device having a conveying member for conveying the developer in the developing container, and the conveying member Driving means, control means for controlling the driving means, and an output unit for outputting information for instructing removal of the developing device or information relating to abnormality of the device, wherein the developer container contains developer. An accommodating portion that accommodates the accommodating portion; and a discharging portion that is connected to the accommodating portion and conveys the developer to the discharge port. The conveying member is disposed in the accommodating portion, and the developer in the accommodating portion is A main transport section that transports toward the discharge section, a sub transport section that transports the developer in a direction opposite to the developer transport direction by the main transport section before the discharge section of the housing section, and the discharge section Placed in the said containment And a discharge transport unit that transports the developer transported to the discharge unit beyond the sub transport unit toward the discharge port, and the control means is configured to connect the information from the output unit. In the image forming apparatus, the driving unit is automatically driven when the signal is output.

  The present invention also provides an apparatus main body, a developing container which is detachable from the apparatus main body and has a discharge port for discharging the developer, a developing apparatus having a conveying member for conveying the developer in the developing container, and the conveying member. Drive means, control means for controlling the drive means, and an input part for inputting information for instructing removal of the developing device, wherein the developing container contains a developer. And a discharge portion connected to the storage portion and transporting the developer to the discharge port, and the transport member is disposed in the storage portion, and the developer in the storage portion is transferred to the discharge portion. A main transport unit that transports the developer, a sub transport unit that transports the developer in a direction opposite to the developer transport direction by the main transport unit before the discharge unit of the storage unit, and the discharge unit. The sub-conveying section extends beyond the accommodating section And a discharge conveyance unit that conveys the developer conveyed to the discharge unit toward the discharge port, and the control unit inputs an instruction to remove the developing device by the input unit. In this case, the image forming apparatus drives the driving unit.

  The present invention also provides an apparatus main body, a developing container which is detachable from the apparatus main body and has a discharge port for discharging the developer, a developing apparatus having a conveying member for conveying the developer in the developing container, and the conveying member. Drive means, control means for controlling the drive means, and judgment means for judging that the developing device needs to be removed, the developer container containing a developer, A discharge unit connected to the storage unit and transporting the developer to the discharge port, and the transport member is disposed in the storage unit, and the developer in the storage unit is directed toward the discharge unit. A main transport unit that transports, a sub transport unit that transports developer in a direction opposite to the developer transport direction by the main transport unit before the discharge unit of the storage unit, and the discharge unit that is disposed in the storage unit. Past the sub-transport section from the section A discharge transport unit that transports the developer transported to the discharge unit toward the discharge port is integrally connected, and the control unit determines that the determination unit needs to remove the developing device. In this case, the image forming apparatus is characterized in that the driving means is automatically driven.

  Further, the present invention comprises an apparatus main body, a developing container that is detachable from the apparatus main body and has a discharge port for discharging the developer, and a developing device having a transport member that transports the developer in the developing container, The developer container includes a storage unit that stores a developer, and a discharge unit that is connected to the storage unit and transports the developer to the discharge port, and the transport member is disposed in the storage unit. A main transport unit that transports the developer in the storage unit toward the discharge unit, and transports the developer in a direction opposite to the developer transport direction by the main transport unit before the discharge unit of the storage unit. A sub-transport unit and a discharge transport unit that are disposed in the discharge unit and transport the developer transported from the storage unit to the discharge unit beyond the sub-transport unit toward the discharge port are integrally connected. Configured to manually drive the conveying member. In the image forming apparatus characterized by having a drive means.

  According to the present invention, the developer accumulated near the discharge port for discharging the developer is discharged by the discharge transfer unit by driving the transfer member when an instruction to remove the developing device from the apparatus main body is given. it can. For this reason, it is possible to prevent the developer from spilling when the developing device is detached from the apparatus main body.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view of the developing device according to the first embodiment. Similarly a cross-sectional view. Similarly longitudinal section. The perspective view of the stirring conveyance screw which concerns on 1st Embodiment. The top view which expands and similarly shows the discharge screw part side of a stirring conveyance screw. 1 is a block diagram showing a control circuit of an image forming apparatus according to a first embodiment. 1A is a diagram illustrating an example of an operation unit of the image forming apparatus according to the first embodiment, FIG. 2B is a diagram illustrating an example of replacement of a developing device displayed on the operation unit, and FIG. 2C is an error display on the operation unit. FIG. 4A and 4B are diagrams sequentially illustrating screens displayed on an operation unit when the developing device is replaced in the first embodiment. 6 is a flowchart illustrating an example of a developing device replacement mode according to the first embodiment. The figure which shows the relationship between the rotational speed of the stirring conveyance screw with respect to developer amount, and the maximum agent surface height. FIG. 5A is a schematic diagram illustrating a state in which the developer is discharged in the developing device replacement mode according to the first embodiment, and FIG. FIG. 10 is a schematic diagram illustrating various parameters of a developing device according to a second embodiment of the present invention. The schematic diagram which shows a mode that a developing agent is skipped by the stirring conveyance screw.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the image forming apparatus of the present embodiment will be described with reference to FIG.

[Image forming apparatus]
The image forming apparatus 100 is an electrophotographic full-color printer provided corresponding to four colors of yellow, magenta, cyan, and black and having four image forming units 1Y, 1M, 1C, and 1Bk. The image forming apparatus 100 is a toner image according to an image signal from a document reading device (not shown) connected to the image forming apparatus main body or a host device such as a personal computer connected to the image forming apparatus main body so as to be communicable. (Image) is formed on the recording material P. Examples of the recording material include sheet materials such as paper, plastic film, and cloth. The outline of such an image forming process will be described. First, in each of the image forming units 1Y, 1M, 1C, and 1Bk, the photosensitive drums (electrophotographic photosensitive members) 2Y, 2M, 2C, and 2Bk as image carriers are respectively provided. Each color toner image is formed. The toner images of the respective colors thus formed are transferred onto the intermediate transfer belt 16 and subsequently transferred onto the recording material P from the intermediate transfer belt 16. The recording material to which the toner image has been transferred is conveyed to the fixing device 13 and the toner image is fixed to the recording material. This will be described in detail below.

  The four image forming units 1Y, 1M, 1C, and 1Bk included in the image forming apparatus 100 have substantially the same configuration except that the development colors are different. Accordingly, in the following, when no particular distinction is required, the subscripts Y, M, C, and Bk attached to the reference numerals to indicate that the element belongs to any one of the image forming units will be omitted, and a general description will be given. .

  The image forming unit 1 is provided with a cylindrical photosensitive member, that is, a photosensitive drum 2 as an image carrier. The photosensitive drum 2 is rotationally driven in the arrow direction in the figure. Around the photosensitive drum 2, a charging roller 3 as a charging unit, a developing device 4 as a developing unit, a primary transfer roller 5 as a transfer unit, and a cleaning device 6 as a cleaning unit are arranged. A laser scanner (exposure device) 7 as an exposure unit is disposed above the photosensitive drum 2 in the drawing.

  Further, an intermediate transfer belt 16 is disposed to face the photosensitive drum 2 of each image forming unit 1. The intermediate transfer belt 16 is stretched by the driving roller 9, the secondary transfer inner roller 10, and the stretching roller 12, and rotates in the direction of the arrow in the drawing by driving the driving roller 9. A secondary transfer outer roller 15 is disposed at a position facing the secondary transfer inner roller 10 and the intermediate transfer belt 16, and a secondary transfer portion T <b> 2 that transfers the toner image on the intermediate transfer belt 16 to the recording material P. Is configured. A fixing device 13 is disposed downstream of the secondary transfer portion T2 in the recording material conveyance direction.

  A process for forming, for example, a four-color full-color image by the image forming apparatus 100 configured as described above will be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum 2 is uniformly charged by the charging roller 3. At this time, a charging bias is applied to the charging roller 3 from a charging bias power source. Next, the photosensitive drum 2 is exposed with a laser beam corresponding to an image signal emitted from the exposure device 7. As a result, an electrostatic latent image corresponding to the image signal is formed on the photosensitive drum 2. The electrostatic latent image on the photosensitive drum 2 is visualized by toner stored in the developing device 4 and becomes a visible image. In this embodiment, a reversal development method is used in which toner is attached to the bright portion potential exposed by laser light.

  The toner image formed on the photosensitive drum 2 is primarily transferred to the intermediate transfer belt 16 at the primary transfer portion T1 configured with the primary transfer roller 5 arranged with the intermediate transfer belt 16 interposed therebetween. At this time, a primary transfer bias is applied to the primary transfer roller 5. The toner remaining on the surface of the photosensitive drum 2 after the primary transfer (transfer residual toner) is removed by the cleaning device 6.

  Such an operation is sequentially performed in each of the yellow, magenta, cyan, and black image forming units, and the four color toner images are superimposed on the intermediate transfer belt 16. Thereafter, the recording material P stored in a recording material storage cassette (not shown) is conveyed from the supply roller 14 by the secondary transfer portion T2 in accordance with the toner image formation timing. Then, by applying a secondary transfer bias to the secondary transfer outer roller 15, the four-color toner images on the intermediate transfer belt 16 are secondarily transferred collectively onto the recording material P. The toner remaining on the intermediate transfer belt 16 without being completely transferred at the secondary transfer portion T2 is removed by the intermediate transfer belt cleaner 18.

  Next, the recording material P is conveyed to a fixing device 13 as a fixing unit. Then, the toner on the recording material P is melted and mixed by being heated and pressed by the fixing device 13 and fixed on the recording material P as a full-color image. Thereafter, the recording material P is discharged out of the apparatus. Thereby, a series of image forming processes (image forming operations) is completed. Note that it is also possible to form a single color or a plurality of colors of a desired color using only a desired image forming unit.

[Developer]
Next, the developing device 4 of this embodiment will be described with reference to FIGS. In this embodiment, as described above, the configurations of the developing devices for yellow, magenta, cyan, and black are all the same. The developing device 4 includes a developing container 40 that contains a two-component developer (hereinafter referred to as a developer) containing non-magnetic toner particles (toner) and magnetic carrier particles (carrier) as main components. In this embodiment, the mixing ratio of the toner and the carrier is about 1: 9 by weight. This ratio should be adjusted appropriately according to the charge amount of the toner, the particle diameter of the carrier, the configuration of the image forming apparatus 100, etc., and does not necessarily have to follow this value.

  The developing device 4 can be detached from the apparatus main body 101 (FIG. 1) of the image forming apparatus 100 and attached to the apparatus main body 101. In the mounted state, as shown in FIG. Placed in. In the developing device 4, a developing region portion of the developing container 40 facing the photosensitive drum 2 is opened, and a developer having a magnet 41 disposed in a non-rotating manner so as to be partially exposed to the opening portion. A developing sleeve 42 serving as a carrier is rotatably installed. The developing sleeve 42 is formed of a non-magnetic material, and rotates in the direction of arrow A in FIG. 3 during the developing operation to hold the two-component developer in the developing container 40 in a layered manner and transport it to the developing region. Then, a developer is supplied to the photosensitive drum 2 in the development area, and the electrostatic latent image formed on the photosensitive drum 2 is developed. The developer after developing the latent image is collected in the developing container 40 as the developing sleeve 42 rotates.

  In the developing container 40, a developing chamber 43 serving as a first chamber capable of storing the developer, and a circulation path for circulating the developer are formed by communicating with the developing chamber 43, and a first container capable of storing the developer. Two stirring chambers 44 are provided. A first agitating and conveying screw 45 and a second agitating and conveying screw 46 are provided as conveying members for conveying the developer in the developing chamber 43 and the agitating chamber 44. The agitation chamber 44 is provided with a supply port (not shown) for supplying a developer having toner and carrier from the developer supply device 60 (FIG. 3).

  A partition wall 50 is provided between the developing chamber 43 and the stirring chamber 44. At both ends of the partition wall 50, as shown in FIG. 2, openings 51 and 52 for delivering the developer are provided. In the present embodiment, an opening 52 is provided on the back side of the partition wall 50 and an opening 51 is provided on the front side. FIG. 3 shows a cross section of the developing device 4 as viewed from the back side of the apparatus main body 101, and the front side of FIG. 3 corresponds to the back side of the apparatus main body 101. Then, the two-component developer is conveyed and circulated in the developing container 40 while being agitated and mixed by the first agitating and conveying screw 45 and the second agitating and conveying screw 46 provided in the developing chamber 43 and the agitating chamber 44, respectively. The developer transport directions are in the direction of arrow B in FIG. 2 in the developing chamber 43 and in the direction of arrow C in the stirring chamber 44, and are transported in opposite directions.

  Further, as shown in FIG. 4, the stirring chamber 44 is provided with a discharge port 47 for discharging the developer in the stirring chamber 44. The discharge port 47 is provided outside the circulation path on the downstream side in the developer conveyance direction in the stirring chamber 44. That is, a discharge path 48 serving as a discharge unit is connected to the downstream end of the stirring chamber 44 in the developer transport direction, which is also a storage unit for storing the developer. A discharge port 47 is provided on the downstream side in the developer transport direction of the discharge path 48 so as to open downward in the gravity direction in the installed state.

  In order to transport the developer from the stirring chamber 44 to the discharge port 47 in this way, the second stirring and transporting screw 46 is configured as shown in FIGS. That is, as shown in FIG. 5, the main conveying screw part 46a as the main conveying part, the return screw part 46b as the auxiliary conveying part, and the discharging screw part 46c as the discharging and conveying part are integrally connected, and the second stirring A conveying screw 46 is configured. Specifically, each screw portion is configured by providing spiral blades on the rotation shaft 46d (on the rotation shaft). The main conveying screw part 46a is arranged in the agitating chamber 44 (inside the accommodating part), and conveys the developer in the agitating chamber 44 in the direction of arrow C in FIG. The return screw portion 46b conveys the developer in a direction opposite to the developer conveyance direction by the main conveyance screw portion 46a before the discharge path 48 of the stirring chamber 44. Here, “convey in the opposite direction” means not to return all of the developer but to convey a part in the opposite direction. The discharge screw part 46 c is arranged in the discharge path 48 and conveys the developer conveyed from the stirring chamber 44 to the discharge path 48 beyond the return screw part 46 b toward the discharge port 47.

  Here, the rotation shaft 46d is rotationally driven by a developing motor 205 (FIG. 7 described later). In addition, each screw part can convey the developer as described above by the rotation of the rotating shaft 46d by appropriately setting the inclination direction, the angle, and the diameter of the blade. More specifically, as shown in FIG. 4, a discharge port 47 is provided on the downstream side of the second stirring and conveying screw 46 of the developing device 4 in the developer conveying direction. A discharge screw part 46c is provided between the discharge port 47 and the stirring chamber 44 of the developing container 40 as shown in FIGS. Further, a return screw portion 46b that conveys the developer in a direction opposite to the main conveyance screw portion 46a is provided between the main conveyance screw portion 46a and the discharge screw portion 46c.

  On the downstream side of the main conveying screw part 46a and the return screw part 46b in the developer conveying direction, a discharge path 48 for discharging the developer is provided continuously to the developer conveying path 49 provided with the main conveying screw part 46a. ing. The height level of the bottom surface 48 a of the discharge path 48 is set to a level higher than the height level of the bottom surface 49 a of the transport path 49. The discharge path 48 is provided with a discharge screw portion 46 c that discharges excess developer to the discharge port 47. The conveying direction of the discharge screw part 46c is the same as the conveying direction of the main conveying screw part 46a.

  The developer replenishment and recovery operations in the developing apparatus 4 of this embodiment configured as described above will be described. As the replenishment developer, a developer containing a carrier in a certain proportion (about 10% by weight) is used. The ratio is not limited to this. As described above, the toner consumed by the image formation is used as the replenishment developer containing the carrier at a certain ratio, and the second agitation and conveyance screw of the developing container 40 is rotated by the rotation of the replenishment screw included in the developer replenishment device 60. 46 is supplied from the upstream side in the developer conveyance direction.

  If replenishment is performed so as to keep the toner density of the developer inside the developing container 40 constant, the amount of the developer in the developing container 40 increases with image formation. Since the replenishment developer is 90% toner and 10% carrier, the toner is consumed by the image formation, but the carrier is not consumed but remains in the developing container, and the replenishment is repeated to increase the amount of the developer. . When the amount of the developer increases in this way, a part of the developer conveyed by the main conveying screw part 46a of the second agitating and conveying screw 46 gets over the return screw part 46b and reaches the discharge path 48. And it is conveyed to the discharge port 47 by the discharge screw part 46c. The developer conveyed to the discharge port 47 is discharged from the discharge port 47 and transferred to the collection container 61 where it is collected and stored.

  In this way, the consumed toner is replenished by the replenishment developer, and at the same time, the developer concentration in the developer container 40 is kept constant while discharging the developer whose carrier is excessive. The component developer is automatically and gradually replaced.

[Developer]
Here, the two-component developer composed of toner and carrier contained in the developing container 40 will be described in detail. The toner includes colored resin particles containing a binder resin, a colorant, and other additives as necessary, and colored particles to which an external additive such as colloidal silica fine powder is externally added. Yes. The toner is a negatively chargeable polyester resin, and the volume average particle size is preferably 4 μm or more and 10 μm or less. More preferably, it is 8 μm or less. In this embodiment, it is assumed that the toner having a volume average particle diameter of 6 μm and a particle diameter of 8 μm or more is 10% of the whole, and that a toner having a particle diameter of 9 μm or more is 3% of the whole.

As the carrier, for example, surface-oxidized or non-oxidized iron, nickel, cobalt, manganese, chromium, rare earth and other metals and their alloys, or oxide ferrite can be preferably used. The method for producing the particles is not particularly limited. The carrier has a weight average particle diameter of 20 to 60 μm, preferably 30 to 50 μm, and a resistivity of 10 ⁷ Ωcm or more, preferably 10 ⁸ Ωcm or more. In this embodiment, 10 ⁸ Ωcm is used.

  For the toner used in this embodiment, the volume average particle diameter was measured by the following apparatus and method. As a measuring device, an SD-2000 sheath flow electric resistance type particle size distribution measuring device (manufactured by Sysmex Corporation) was used. The measuring method is as follows. That is, 0.1 ml of surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of 1% NaCl aqueous electrolytic solution prepared using primary sodium chloride, and 0.5 to 50 mg of a measurement sample is added. Add. The electrolytic aqueous solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. Then, by using the SD-2000 sheath flow electrical resistance type particle size distribution measuring apparatus, the particle size distribution of 2 to 40 μm particles is measured using a 100 μm aperture as the aperture to obtain a volume average distribution. The volume average particle diameter is obtained from the volume average distribution thus obtained.

In addition, a sandwich type cell having a measurement electrode area of 4 cm ² and an interelectrode spacing of 0.4 cm was used as the carrier resistivity used in this embodiment. Measurement was performed by applying an applied voltage E (V / cm) between the two electrodes to one electrode under a pressure of 1 kg and obtaining the carrier resistivity from the current flowing in the circuit.

[Developer removal operation]
Next, an operation when the developing device 4 is detached from the apparatus main body 101 in this embodiment will be described with reference to FIGS. FIG. 7 is a schematic diagram of a control circuit diagram of the image forming apparatus 100 of the present embodiment. A control unit 200 of the image forming apparatus 100 as a control unit of the present embodiment includes a CPU 201, a ROM 202, and a RAM 203, and performs image formation by controlling an image forming engine unit 204 including various motors and a power source. The image forming engine unit 204 includes a developing motor 205 as a driving unit. The developing motor 205 rotates and drives the first stirring and conveying screw 45, the second stirring and conveying screw 46, and the developing sleeve 42 of the developing device 4. The control unit 200 is connected to an operation unit (UI: user interface) 300 as an input unit. Specific examples of the operation unit 300 include an operation panel provided in the apparatus main body 101 and an external input terminal such as a personal computer.

  The CPU 201 stores in the RAM 203 the number of image formations (the number of image formations, the number of rotations of the developing sleeve, or the rotation time). When the number of times of image formation reaches the preset life counter of the developing device 4, the CPU 201 sends a sign prompting the developing device replacement work (instructing removal of the developing device 4) to the operation unit (output unit) 300. Display. Here, when the sign is displayed, the operation associated with image formation is stopped. The operations associated with image formation include, in addition to normal image forming operations, between images during continuous image formation (between sheets), a pre-rotation operation, and a post-rotation operation. The pre-rotation operation is an operation for driving the photosensitive drum or the like for a predetermined time before the start of the image forming operation, and the post-rotation operation is an operation for driving the photosensitive drum or the like for a predetermined time after the end of the image forming operation. In any case, the developing device 4 is driven, and the driving of the developing device 4 is stopped when the sign is displayed. An example of the operation unit 300 is shown in FIG. As shown in FIG. 8A, the operation unit 300 is provided with a display unit 301 that can display various signatures. An example of a sign that prompts the display unit 301 to replace the developing device is shown in FIG. In addition, as shown in FIG. 8C, the display unit 301 displays an error (information related to an abnormality in the apparatus) when an abnormality occurs in the image forming apparatus. When displaying such a sign or error display on the external input terminal, the CPU 201 functions as an output unit that outputs the sign or error to the external input terminal.

  In the present embodiment, a case where the user replaces the developing device 4 will be described as an example. As described above, when the developing device replacement sign is displayed on the display unit 301 and the user presses the user mode button 302 (FIG. 8A) of the operation unit 300, the display unit 301 displays FIG. 9A. Is displayed. Next, when the user touches the adjustment mode button 303, a screen shown in FIG. Next, when the user touches the developing device replacement mode button 304, the screen shown in FIG. Then, when the user designates colors (in this embodiment, four types of Y, M, C, and Bk, but not limited thereto), the developing device replacement operation is started.

  As shown in FIG. 10, when the developing device replacement mode button 304 is touched in FIG. 9B, the developing device replacement mode is started, and the CPU 201 that receives a command from the operation unit 300 prepares to send a command to the developing motor 205. Is started (S1). Next, the developing motor of the developing device to be operated is selected by performing color selection designated by the operation unit 300 on the screen of FIG. 9C (S2). Then, in response to a command from the CPU 201, the developing motor 205 of the designated color image forming engine is driven to start the operation of rotating the second stirring and conveying screw 46 of the developing device 4 (S3). Here, the time of the developing motor 205 designated in advance in the ROM 202 is confirmed. In this embodiment, the setting is made to rotate for 10 seconds (S4). Next, when the second agitating / conveying screw 46 rotates until the designated time, the developing motor 205 is stopped (S5). When the driving of the developing motor 205 is stopped, the developing device replacement mode is ended and the developing device can be removed.

  As described above, in the present embodiment, when the developing device 4 is removed from the apparatus main body 101, the second agitating and conveying screw 46 is removed before the developing apparatus 4 is detached from the apparatus main body 101 after the drive associated with image formation is stopped. Driven. That is, the CPU 201 of the control unit 200 drives the developing motor 205 when removing the developing device 4 after the operation accompanying the image formation including the post-rotation operation is stopped and the driving of the developing device 4 is also temporarily stopped. Specifically, when an instruction to remove the developing device is given by the operation unit 300, the developing motor 205 of the developing device 4 that has been stopped is driven. As a result, when the second agitating and conveying screw 46 is rotated, the discharge screw portion 46 c is also rotated, so that the developer accumulated in the discharge path 48 is discharged from the discharge port 47 to the collection container 61.

  Here, in this embodiment, the rotation speed of the developing motor 205 that rotates the second stirring and conveying screw 46 is the same as that during normal image formation. However, the rotation speed of the developing motor 205 may be faster or slower than the rotation speed during the normal image forming operation. If the rotation speed of the developing motor 205 at the time of removing the developing device 4 is made faster than that at the time of image formation, the developer surface height of the developer may increase, and the developer in the discharge path 48 is discharged. It may take time. On the other hand, when the rotational speed is slowed down, the force for jumping up the developer is weakened and the surface height of the developer is low and stable, and it takes no time to discharge the developer in the discharge path 48. Therefore, it is preferable that the driving speed of the second stirring and conveying screw 46 when removing the developing device 4 is slower than the driving speed of the second stirring and conveying screw 46 at the time of image formation. In any case, the driving time of the development motor 205 set in advance as described above is such that the developer in the discharge path 48 is reliably discharged from the discharge port 47 in consideration of the rotational speed of the development motor 205 and the like. It is preferable to set to.

  FIG. 11 shows the relationship between the rotation speed of the developing motor and the maximum developer surface height of the developer in the return screw portion 46b. As shown in the figure, it can be seen that the lower the rotational speed to some extent, the lower the surface height of the agent and the amount of agent flowing in the discharge path 48 decreases. That is, as the surface height of the developer increases, the amount of developer that gets over the return screw portion 46 b and is transported to the discharge path 48 increases, and it takes time to discharge the developer from the discharge port 47. Therefore, it is desirable to calculate and set the driving speed of the second agitating and conveying screw 46 so as to have a surface level lower than the height of the return screw portion 46b.

  In the case of this embodiment, the developer accumulated in the vicinity of the discharge port 47 for discharging the developer is discharged by driving the second stirring and conveying screw 46 before removing the developing device 4 from the apparatus main body 101. It can be discharged by the screw part 46c. That is, as shown in FIG. 12A, the second agitating and conveying screw 46 is driven by driving the developing motor 205, and the developer t (textured portion) in the discharge path 48 is discharged to the discharge screw portion 46c. It is conveyed to the outlet 47. At this time, since the developing device 4 is before being removed from the apparatus main body 101, the shutter 63 of the discharge port 47 is opened, and the developer t is placed in the collection container 61 (see FIG. 4) connected to the discharge port 47. Discharged. Then, by rotating the discharge screw portion 46c for a predetermined time (10 sec in the present embodiment), the developer t in the discharge path 48 is discharged as shown in FIG.

  For this reason, according to the present embodiment, it is possible to prevent the developer from spilling when the developing device 4 is detached from the apparatus main body 101. For example, the developer spills from the vicinity of the shutter 63 of the developer discharge port 47 into the apparatus main body 101 or around the apparatus main body 101 due to vibration of the removing operation of the developing apparatus 4 or tilting of the developing apparatus 4 during removal. Can be suppressed. As a result, the amount of developer spilling in the vicinity of the developer discharge port 47 accompanying the replacement operation of the developing device 4 can be reduced, and developer contamination can be prevented.

  In the case of the present embodiment, the user operates the operation unit with a sign of replacement of the developing device, so that the second agitating and conveying screw 46 is driven for a predetermined time before the developing device 4 is removed. However, when an error is displayed on the image forming apparatus 100, there may be other causes, but it may be assumed that the developer spills into the main body due to vibration of the image forming apparatus or the like for main body maintenance. For this reason, in such a case, the second stirring and conveying screw 46 of the developing device 4 may be automatically rotated. That is, the CPU 201 determines as a determination means that the developing device 4 needs to be removed due to an error or the like. When it is determined that the developing device 4 needs to be removed, the developing motor 205 is automatically driven as described above to discharge the developer in the discharge path 48 of the developing container 40. good. When driving automatically as described above, the developing motor 205 may be continuously driven without stopping the driving accompanying image formation.

  In addition, a hard switch (manual drive means) is mounted in the apparatus main body 101 so that the second agitating and conveying screw 46 of the developing device 4 can be driven whenever the developing device is replaced when the image forming operation is defective. May be. As such a hard switch, a user manually pushes the second agitating and conveying screw 46 such as a button for rotating the second agitating and conveying screw 46 by a pushing operation, a handle or a lever for rotating the second agitating and conveying screw 46. Anything can be used.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to FIGS. In the case of the first embodiment described above, during the replacement operation of the developing device 4, the second stirring and conveying screw 46 was rotated for 10 seconds. That is, the developer in the vicinity of the discharge port 47 is surely discharged by rotating the second agitating and conveying screw 46 for a long time. However, the longer the time when the developing device 4 is replaced, the more the user feels stress. Therefore, in the present embodiment, the optimum rotation time of the second agitating and conveying screw 46 during the replacement operation is calculated according to the shape of each part of the developing device 4 so that the replacement operation of the developing device 4 can be performed in as short a time as possible. I made it. Since other configurations and operations are the same as those in the first embodiment described above, the same components are denoted by the same reference numerals, detailed illustration and description thereof are omitted or simplified, and hereinafter the first embodiment. It demonstrates centering on a different part.

In FIG. 13, the parameters of the stirring chamber 44 and the second stirring and conveying screw 46 of the developing device 4 of the present embodiment are indicated by symbols. First, the predetermined time for rotating the second stirring and conveying screw 46 is T, the angular velocity of the discharge screw portion 46c (same as the angular velocity of the developing motor 205) is ω, and the blade from the return screw portion 46b of the discharge screw portion 46c to the discharge port 47 Let P be the number of turns. That is, let P be the number of wings of the discharge screw portion 46c between the end of the return screw portion 46b on the discharge screw portion 46c side and the discharge port 47. In this case,
T ≧ (2π / ω) × P (1)
If the predetermined time T is set so as to satisfy the condition, the developer in the discharge path 48 is discharged from the discharge port 47.

Next, let R be the distance (screw diameter) between one point on the circumference of the blade of the main conveying screw part 46a and one point on the circumference farthest from this one point. Further, an angle of a line connecting these two points with respect to the rotation axis M of the second stirring and conveying screw 46 is defined as θ. Further, the length of the return screw portion 46b in the conveying direction is L, and the gravitational acceleration is g. In this case,
L ≧ (R × ω) ² × sin θ × cos θ / 2 / g (2)
It is preferable to set the angular velocity ω so as to satisfy the above. This point will be described with reference to FIG.

FIG. 14 simply shows a case where the developer t flies from the top of the blades of the main conveying screw part 46a by the rotation of the main conveying screw part 46a. As shown in FIG. 14, the developer t is ejected from the main conveying screw portion 46 a at a speed V. At this time, when the flight time of the developer t is τ,
L ≧ V · cos θ · τ (3)
If the time τ is set so as to satisfy the condition, it can be assumed that the developer t ejected from the main transport screw portion 46a falls into the return screw portion 46b and does not reach the discharge screw portion 46c. Since V = (R / 2) ω, equation (3) is
L ≧ (R / 2) ω · sin θ · τ (4)
It becomes.

On the other hand, assuming a time when the developer t is blown and returned to the same height position (y-direction position) as the point where the developer is blown, τ is a parabolic motion.
y = V · cos θ · τ− (g / 2) τ ² (5)
It is expressed.

  Here, when y = 0, the time τ has elapsed, and is expressed by V = (R / 2) ω, so the above equation becomes as follows.

0 = (R / 2) ω · cos θ · τ− (g / 2) τ ²
So that
τ = (ω · R / g) · cos θ (6)
It becomes.

  When this equation (6) is substituted into equation (4), the above-described equation (2) is obtained. Therefore, the angular velocity ω satisfying the expression (2) is the maximum velocity at which the developer t ejected from the main conveyance screw portion 46a does not reach the discharge screw portion 46c.

  As described above, the angular velocity ω of the discharge screw portion 46c is set so as to satisfy the equation (2), and ω set in this way is substituted into the equation (1), so that in the configuration, the angular velocity ω in the discharge path 48 can be obtained in the shortest time. A predetermined time during which the developer can be discharged can be obtained. That is, by satisfying the expressions (1) and (2), the driving time of the developing motor 205 during the replacement operation of the developing device 4 can be set to a shorter time (such as the shortest time). In addition, it is desirable to incorporate many other parameters such as the developer amount and the developer deterioration state, but it has been confirmed that the effect is largely obtained by the above conversion formula.

Here, as an example of the second agitating and conveying screw 46, the shortest rotation speed and time by a screw shape having the following numerical values are determined.
L = 5mm, P = 4, R = 16mm, θ = 45 °
Substituting the above parameters into equation (2)
5 mm ≧ (16 mm × ω) ² × √2 ÷ 8 ÷ (9.8 × 10 ³ mm / sec)
ω ≦ 32.9 [rad / sec] ≈314 [rpm]
T ≧ 0.76 [sec]
As mentioned above, although an example of a certain screw shape was shown, if it is the conditions which satisfy | fill the said Formula, it will not be this limitation.

  In the case of the present embodiment, by determining the optimal rotation time of the discharge screw portion 46c, there is no stress on the user during maintenance or replacement of the developing device 4, and the developer near the developer discharge port 47 It becomes possible to prevent contamination.

  In each of the above-described embodiments, the case where the developer discharge port 47 faces downward in the gravity direction has been described. However, the present invention can be applied to a configuration in which, for example, the discharge port 47 opens in another direction such as a horizontal direction.

<Other embodiments>
In each of the above-described embodiments, the driving time for driving the second stirring and conveying screw when the developing device is removed has been described as being constant. However, the present invention is not limited to this. For example, when the amount of developer in the developing container (in the discharge portion) immediately before removal is small, the driving time can be shortened. Therefore, the driving amount of the second agitating / conveying screw may be changed by predicting the amount of developer in the discharge portion based on the image ratio printed immediately before removal or the toner consumption (toner replenishment amount). That is, when the image ratio is small, it may be determined that the amount of the developer in the discharge portion is small, and the driving time of the second agitating and conveying screw may be set small.

  4 ... developing device / 40 ... developing container / 44 ... stirring chamber (accommodating portion) / 46 ... second stirring and conveying screw (conveying member) / 46a ... main conveying screw portion (main conveying) Part) / 46b ... return screw part (sub-conveying part) / 46c ... discharge screw part (discharge conveying part) / 46d ... rotary shaft / 47 ... discharge port / 48 ... discharge path ( Discharging unit) / 100 Image forming apparatus / 101 Apparatus main body / 200 Control unit (control unit) / 201 CPU (determination unit) / 205 Development motor (driving unit)

Claims (8)

The device body;
A developing device detachable from the apparatus main body, having a discharge port for discharging the developer, and a developing device having a transport member for transporting the developer in the developer container;
Driving means for driving the conveying member;
Control means for controlling the drive means;
Information for instructing removal of the developing device, or an output unit for outputting information on abnormality of the device,
The developer container includes a storage unit that stores a developer, and a discharge unit that is connected to the storage unit and transports the developer to the discharge port.
The transport member is disposed in the storage unit, and transports the developer in the storage unit toward the discharge unit, and developer transport by the main transport unit before the discharge unit of the storage unit A sub-conveying section that conveys the developer in a direction opposite to the direction; and a developer that is disposed in the discharge section and that is conveyed from the storage section to the discharge section beyond the sub-transport section toward the discharge port. Constructed by connecting the discharge conveyance part to convey integrally,
The control means automatically drives the drive means when the information is output from the output unit.
An image forming apparatus. The device body;
A developing device detachable from the apparatus main body, having a discharge port for discharging the developer, and a developing device having a transport member for transporting the developer in the developer container;
Driving means for driving the conveying member;
Control means for controlling the drive means;
An input unit for inputting information for instructing removal of the developing device;
The developer container includes a storage unit that stores a developer, and a discharge unit that is connected to the storage unit and transports the developer to the discharge port.
The transport member is disposed in the storage unit, and transports the developer in the storage unit toward the discharge unit, and developer transport by the main transport unit before the discharge unit of the storage unit A sub-conveying section that conveys the developer in a direction opposite to the direction; and a developer that is disposed in the discharge section and that is conveyed from the storage section to the discharge section beyond the sub-transport section toward the discharge port. Constructed by connecting the discharge conveyance part to convey integrally,
The control means drives the driving means when an instruction to remove the developing device is input by the input unit.
An image forming apparatus. The device body;
A developing device detachable from the apparatus main body, having a discharge port for discharging the developer, and a developing device having a transport member for transporting the developer in the developer container;
Driving means for driving the conveying member;
Control means for controlling the drive means;
Determining means for determining that the developing device needs to be removed;
The developer container includes a storage unit that stores a developer, and a discharge unit that is connected to the storage unit and transports the developer to the discharge port.
The transport member is disposed in the storage unit, and transports the developer in the storage unit toward the discharge unit, and developer transport by the main transport unit before the discharge unit of the storage unit A sub-conveying section that conveys the developer in a direction opposite to the direction; and a developer that is disposed in the discharge section and that is conveyed from the storage section to the discharge section beyond the sub-transport section toward the discharge port. Constructed by connecting the discharge conveyance part to convey integrally,
The control means automatically drives the drive means when the judgment means judges that the developing device needs to be removed.
An image forming apparatus. The control means makes the driving speed of the conveying member when removing the developing device slower than the driving speed of the conveying member during image formation.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The control means drives the transport member for a predetermined time when removing the developing device.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The discharge conveyance unit is a screw having a spiral blade on a rotation shaft,
When the predetermined time is T, the angular velocity of the discharge transport unit is ω, and the number of turns of the blades from the sub transport unit to the discharge port of the discharge transport unit is P,
T ≧ (2π / ω) × P
The predetermined time T is set so as to satisfy
The image forming apparatus according to claim 5, wherein: The main transport unit is a screw having a spiral blade on the rotation axis,
The distance between one point on the circumference of the blade of the main transport unit and one point on the circumference farthest from this point is R, the angle of the line connecting these two points to the rotation axis is θ, and the sub-transport When the length of the part in the conveying direction is L and the gravitational acceleration is g,
L ≧ (R × ω) ² × sin θ × cos θ / 2 / g
The angular velocity ω is set to satisfy
The image forming apparatus according to claim 6. The device body;
A developing container detachable from the apparatus main body, having a discharge port for discharging the developer, and a developing device having a transport member for transporting the developer in the developer container,
The developer container includes a storage unit that stores a developer, and a discharge unit that is connected to the storage unit and transports the developer to the discharge port.
The transport member is disposed in the storage unit, and transports the developer in the storage unit toward the discharge unit, and developer transport by the main transport unit before the discharge unit of the storage unit A sub-conveying section that conveys the developer in a direction opposite to the direction; and a developer that is disposed in the discharge section and that is conveyed from the storage section to the discharge section beyond the sub-transport section toward the discharge port. Constructed by connecting the discharge conveyance part to convey integrally,
Manual driving means for manually driving the conveying member;
An image forming apparatus.

Images