JP2015001605A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of maintaining stable image quality by accurately supplying a constant amount of a carrier to a developing container and to provide an image forming apparatus.SOLUTION: A developing device 412 includes a guide part 120 including a first communication port 122 for introducing the carrier supplied from a carrier supply part 90 which is provided independently of a toner supply part 82 supplying toner to a developing container 816 through a toner supply path 83 and supplies the carrier to the developing container 816 by causing the carrier to freely drop through a carrier supply path 97, and a second communication port 124 for delivering the carrier to the developing container 816, and arranged above the developing container 816. The first communication port 122 and the second communication port 124 are arranged in positions not overlapped in a gravity direction and a slope part 128 guiding the carrier introduced through the first communication port 122 to the second communication port 124 is formed between the first communication port 122 and the second communication port 124.

Description

  The present invention relates to a developing device and an image forming apparatus.

  In general, an image forming apparatus (printer, copier, facsimile, etc.) using an electrophotographic process technology generates an electrostatic latent image by irradiating (exposing) a charged photoconductor with a laser beam based on image data. Form. Then, by supplying toner from the developing device to the photosensitive member (image carrier) on which the electrostatic latent image is formed, the electrostatic latent image is visualized to form a toner image. Further, after the toner image is directly or indirectly transferred to the paper, it is fixed by heating and pressurizing to form an image on the paper.

  Development methods for forming a toner image on a photoreceptor include a one-component development method that uses only toner as the main component of the developer and a two-component development method that uses toner and a carrier as the main components of the developer. In the two-component development method, the toner and the carrier are mixed and agitated to cause frictional charging in the toner. In order to stably charge the toner, it is ideal that the surface of the carrier does not change.

  In the two-component developing type developing device, the toner is consumed by the developing process, while the carrier is not consumed and remains in the developing device. Therefore, mechanical stress and thermal stress due to contact with the toner are accumulated on the carrier, and the surface is contaminated by the adhesion of the toner. As described above, when the carrier is deteriorated with time, the charge amount of the toner is decreased, so that the image quality is deteriorated such as fogging.

  Therefore, the developer in the developing device is periodically replaced. Further, since the toner consumption level and the carrier deterioration level in the developing device are different, that is, the timing for supplying the toner and the timing for supplying the carrier are different, the toner and the carrier can be supplied independently. A developing device has also been proposed (for example, Patent Document 1).

  Specifically, Patent Document 1 has a plurality of replenishment rollers having a measurement recess formed on the peripheral surface, and the supply roller is rotated to join the carrier introduced into the measurement recess to the toner supply path. A developing device is disclosed in which the toner and the carrier are supplied to the developing unit by the operation of a screw pump after the toner is discharged.

JP 2005-250347 A

  However, in the technique described in Patent Document 1, since the carrier is joined to the toner supply path, frictional charging occurs between the toner and the carrier in the middle of the toner supply path, and the toner adheres to the toner supply path.・ Clogging may occur. In this case, there is a problem in that a carrier of a certain amount cannot be stably replenished to the developing container containing the two-component developer because the carrier transportation in the toner replenishing path is hindered. In order to solve this problem, secondary means such as adjusting the pressure of the screw pump are required.

  In addition, a technique for supplying a developing container separately with a carrier that has fallen freely from a carrier accommodating portion that accommodates the carrier and a toner that has flowed down through a different path from the carrier, instead of merging the carrier with the toner replenishing path. Has been proposed. However, this technique has the following problems. That is, in the developing container, the developer (toner and carrier) is stirred and circulated by a rotating means such as a screw, so that the internal pressure in the developing container increases. Since the internal pressure in the developing container is released from the carrier supply port, the toner scatters or adheres to the carrier supply path disposed immediately above the carrier supply port. Furthermore, frictional charging occurs between the carrier that has flowed down the carrier supply path and the toner that is scattered or adhered in the carrier supply path, so that the amount of toner adhering to the carrier supply path increases. If the carrier flow-down region in the carrier supply path is restricted due to the adhesion of the toner, the transport of the free-falling carrier is hindered, and a fixed amount of carrier cannot be stably supplied to the developing container.

  In some cases, the carrier that has fallen freely along the carrier supply path and the toner that has flowed down the toner supply path are introduced from the same developer supply port. In this case, the carrier supply path is directly above the developer supply port. This causes the same problem as described above.

  As described above, if a certain amount of carrier cannot be accurately supplied to the developing container, the balance between the toner amount and the carrier amount in the developing container may be lost, and the charge amount of the toner may become non-uniform. Quality may be reduced.

  An object of the present invention is to provide a developing device and an image forming apparatus that can accurately supply a fixed amount of carrier to a developing container and maintain stable image quality.

The developing device according to the present invention includes:
A developing device that forms a toner image by developing an electrostatic latent image formed on a photoreceptor with a two-component developer composed of toner and a carrier,
A developer container containing the two-component developer;
A toner supply unit for supplying the toner to the developer container via a toner supply path;
A carrier supply unit that is provided independently of the toner supply unit and that freely drops the carrier through a carrier supply path extending in the direction of gravity and supplies the carrier to the developer container;
A first communication port that is connected to the carrier supply path and introduces the carrier supplied from the carrier supply unit; and a second communication port that leads the carrier to the developer container; A guide unit arranged in
With
The first communication port and the second communication port are arranged at positions where they do not overlap in the direction of gravity, and the first communication port and the second communication port are provided between the first communication port and the second communication port. A slope portion for guiding the carrier introduced through the mouth to the second communication port is formed.

  An image forming apparatus according to the present invention includes the above developing device.

  According to the present invention, since the first communication port and the second communication port are arranged at positions where they do not overlap in the direction of gravity, even if the internal pressure in the developing container is released from the second communication port, It is possible to prevent the toner from scattering or adhering to the carrier supply path connected to the one communication port. Further, frictional charging is prevented from occurring between the carrier flowing down the carrier supply path and the toner scattered or adhered in the guide portion. As a result, the flow of the carrier in the carrier supply path is not restricted by toner adhesion, that is, the carrier that has fallen freely is not hindered, and a certain amount of carrier can be supplied to the developing container with high accuracy and stable. Image quality can be maintained.

1 is a diagram schematically showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus according to the embodiment. It is a figure which shows the structure of a developing device. It is a figure which shows one structural example of the image development part. It is a figure which shows the structure of a guide part. It is BB arrow sectional drawing in FIG. It is a perspective view of a slope part. It is a figure which shows the example of 1 structure of a carrier accommodating part. It is a top view of a carrier guide part. It is XX arrow sectional drawing in FIG. It is a top view of a carrier distribution part. It is an upper perspective view of a carrier distribution part. It is a bottom view of a carrier distribution part. It is a downward perspective view of a carrier distribution part. It is a top view of a support frame. It is an upper perspective view of a support frame. It is a flowchart which shows an example of a carrier supply process. It is a timing chart which shows operation | movement of the measurement roller of a carrier accommodating part. It is a figure which shows a state transition when a carrier distribution part rotates. It is a figure which shows a mode when a support leg part gets over a level | step-difference part. It is a figure which shows the modification of a structure of a guide part. It is CC sectional view taken on the line in FIG.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
[Configuration of Image Forming Apparatus 1]
FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 shows a main part of the control system of the image forming apparatus 1 according to the present embodiment. An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421 (primary transfer). Then, after superposing four color toner images on the intermediate transfer belt 421, the toner images are transferred to the paper S (secondary transfer) to form an image.

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. Tandem system is adopted.

  As illustrated in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, and a control unit 100.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms an image on the paper S based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on the document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like in accordance with a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and explanation, common constituent elements are denoted by the same reference numerals, and Y, M, C, or K are added to the reference numerals when distinguished from each other. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 has an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. It is a negatively charged organic photoconductor (OPC) in which a generation layer (CTL) and a charge transport layer (CTL) are sequentially stacked. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative polarity. The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 is a two-component developing type developing device, and attaches toner of each color component to the surface of the photosensitive drum 413 to visualize the electrostatic latent image to form a toner image. The detailed configuration of the developing device 412 will be described later.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched around a plurality of support rollers 423 in a loop shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the belt running speed constant in the primary transfer portion. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face a roller 423B (hereinafter referred to as “backup roller 423B”) disposed on the downstream side of the driving roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. Specifically, a toner image is applied by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper S (the side in contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The sheet S to which the toner image is transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 includes a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 421 and removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) of the paper S, and the back surface (surface opposite to the fixing surface) of the paper S. A lower fixing unit 60B having a rear side support member to be disposed, a heating source 60C, and the like are provided. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the paper S is formed.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit. The fixing device F may be provided with an air separation unit that separates the sheet S from the fixing surface side member or the back surface side support member by blowing air.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, or the like is stored for each preset type. . The conveyance path unit 53 includes a plurality of conveyance roller pairs such as registration roller pairs 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and a fixing process is performed in the fixing unit 60. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

  FIG. 3 is a diagram illustrating the configuration of the developing devices 412Y, 412M, 412C, and 412K. As shown in FIG. 3, the developing devices 412Y, 412M, 412C, and 412K have developing units 81Y, 81M, 81C, and 81K that develop toner images of respective color components on the photosensitive drums 413Y, 413M, 413C, and 413K, respectively. Toner supply units 82Y, 82M, 82C, and 82K that supply toner of each color component to the units 81Y, 81M, 81C, and 81K, and carrier supply units 90 that supply carriers to the development units 81Y, 81M, 81C, and 81K, And a guide unit 120 for guiding the toner supplied from the toner supply units 82Y, 82M, 82C, and 82K and the carrier supplied from the carrier supply unit to the developing units 81Y, 81M, 81C, and 81K. That is, the developing device 412 has a configuration capable of independently supplying toner and carrier to the developing unit 81.

  The toner supply units 82Y, 82M, 82C, and 82K are provided for the respective developing devices 412Y, 412M, 412C, and 412K, and are connected to the developing units 81Y, 81M, 81C, and 81K through the toner supply paths 83Y, 83M, 83C, and 83K. Is done. A known technique can be applied to the toner supply unit 82.

  The carrier supply unit 90 accommodates a carrier and develops a carrier containing unit 92 that sends out a predetermined amount of carriers, a carrier bottle 91 that is detachably attached to the carrier containing unit 92, and a carrier sent from the carrier containing unit 92 The carrier guide part 93 supplied to each of the parts 81Y, 81M81C, and 81K, and the excitation part 98 that vibrates the carrier guide part 93 (a carrier distribution member 95 to be described later in detail) are provided.

  Only one carrier supply unit 90 is provided in common for the developing devices 412Y, 412M, 412C, and 412K. In order to supply the carrier by utilizing the free fall movement of the carrier due to its own weight, the carrier supply unit 90 is disposed above the development units 81Y, 81M, 81C, and 81K.

  The carrier supply unit 90 supplies a predetermined amount of carrier to the developing units 81Y, 81M, 81C, and 81K via carrier supply paths 97Y, 97M, 97C, and 97K connected to the carrier guide unit 93. The carrier supply paths 97Y, 97M, 97C, and 97K are extended in the direction of gravity from the carrier supply unit 90 toward the guide unit 120. “Extending in the direction of gravity” includes not only strictly extending in the vertical direction but also extending in an inclined or curved manner within a range that does not prevent the carrier from flowing down due to its own weight.

  The vibration unit 98 may be a vibration generating device that vibrates the carrier guide unit 93 from the outside, or may be a unit that generates vibration due to the internal structure of the carrier guide unit 93. In the present embodiment, the carrier guide portion 93 is vibrated by the internal structure of the carrier guide portion 93.

  The guide unit 120 is disposed above the developing unit 81 (developing container 816). The toner that has flowed down the toner supply path 83 and the carrier that has flowed down the carrier supply path 97 are separately introduced into the guide unit 120. The toner and the carrier introduced into the guide unit 120 are supplied to the developing container 816 included in the developing unit 81 through the developer supply port 816a communicating with the guide unit 120 (see FIG. 4). Details of the guide unit 120 will be described later.

  FIG. 4 is a diagram illustrating a configuration example of the developing unit 81. As shown in FIG. 4, the developing unit 81 includes a developing roller 811 (toner carrier), a transport roller 812 (developer carrier), stirring members 813 and 814, a developer regulating member 815, a developing container 816, and the like. . That is, the developing unit 81 forms a toner image on the photosensitive drum 413 by a so-called hybrid development method in which a two-component development method and a one-component development method are combined. 4 is merely an example, and a toner image is formed on the photosensitive drum 413 by using a two-component developer, that is, by a two-component development method (including a hybrid development method). If there is, there is no particular limitation.

  In the developing container 816, an agitating member 814, an agitating member 813, a conveying roller 812, and a developing roller 811 are sequentially arranged from the upstream side to the downstream side in the developer conveying direction (from the right side to the left side in FIG. 4). The developer container 816 has a developer supply port 816a (substantially above the stirring member 814 in FIG. 4) for supplying developer.

  The developer container 816 has a developer discharge port 816b (substantially below the transport roller 812 in FIG. 4) for discharging the developer. The developer in the developer container 816 is periodically discharged through the developer discharge port 816b and recovered in a developer recovery container (not shown).

  The agitating members 813 and 814 are constituted by an agitating screw extending in the axial direction, and agitate while circulating and conveying the developer between the agitating chambers 816c and 816d. As a result, the toner and the carrier contained in the developer come into frictional contact with each other and are charged to opposite polarities. Here, it is assumed that the carrier is positively charged and the toner is negatively charged. The negatively charged toner adheres to the periphery of the positively charged carrier mainly by the electrical attraction force of both. The developer is supplied to the transport roller 812 in the process of being transported by the stirring member 813.

  The conveyance roller 812 is a so-called magnet roller having a magnet body 812a that is fixed so as not to rotate and a cylindrical conveyance sleeve 812b that is rotatably arranged around the magnet body 812a. A developer regulating member 815 is disposed substantially above the conveying sleeve 812b and is spaced apart from the conveying sleeve 812b by a predetermined distance. The developer regulating member 815 is a plate-like member formed of a magnetic material such as a stainless steel material and extends in parallel with the transport roller 812. The magnet body 812a has a plurality of magnetic poles (not shown) extending in the axial direction of the transport roller 812. A magnetic field (lines of magnetic force) for transporting the developer by the transport sleeve 812b is formed by the plurality of magnetic poles.

  The developer supplied to the conveying sleeve 812b rises along the magnetic field lines formed by the magnet body 812a and forms a so-called magnetic brush. The developer is transported counterclockwise as the transport sleeve 812 b rotates, and is regulated to a certain thickness by passing through a gap with the developer regulating member 815.

  The developing roller 811 is a conductive roller made of a metal such as aluminum. The developing roller 811 may be one in which a coating such as a polyester resin is formed on the outer peripheral surface of the conductive roller. By forming an electric field between the developing roller 811 and the transport roller 812, only the toner is detached from the developer transported by the transport sleeve 812b and supplied to the developing roller 811. The developing roller 811 supplies toner to the photosensitive drum 413 to visualize the electrostatic latent image on the photosensitive drum 413.

  Further, the developing unit 81 employs a trickle developing system in which the developer is gradually replaced. That is, the developing unit 81 is configured to periodically replenish the developer from the developer replenishing port 816a and discharge the excess developer from the developer discharge port 816b (trickle mechanism). As the trickle mechanism, a known circulation overflow type or liquid level overflow type can be applied. As a result, the deteriorated carrier is replaced with a new carrier, so that the toner in the developing container 816 is always uniformly charged. Therefore, stable image quality can be realized regardless of the number of prints and environmental changes.

  FIG. 5 is a diagram illustrating a configuration of the guide unit 120. 6 is a cross-sectional view taken along the line BB in FIG. FIG. 7 is a perspective view of the slope portion 128 formed in the guide portion 120.

  The guide unit 120 has a first communication port 122 that is connected to the carrier supply path 97 and introduces the carrier supplied from the carrier supply unit 90 into the guide unit 120 in the upper part in FIG. That is, the internal space of the guide unit 120 and the internal space of the carrier supply path 97 communicate with each other through the first communication port 122 formed in the upper part of the guide unit 120 in FIG.

  The guide unit 120 is connected to a toner supply path 83 extending in the horizontal direction on the right side in FIG. 5 and has a third communication port 126 for introducing the toner supplied from the toner supply unit 82 into the guide unit 120. That is, the internal space of the guide unit 120 and the internal space of the toner supply path 83 communicate with each other through the third communication port 126 formed on the right side of the guide unit 120 in FIG.

  A conveying screw 831 extending in the horizontal direction is disposed in the internal space of the toner supply path 83 and the guide unit 120. One end side of the conveying screw 831 protrudes from the left part in FIG. 5 of the guide part 120 and is connected to a drive part (not shown) including a drive motor and a power transmission mechanism. The other end side of the conveying screw 831 is rotatably supported by the toner supply unit 82. The conveying screw 831 is a spiral screw in which spiral blades 832, 833, 834, and 835 having a predetermined spiral pitch are provided in a portion of the shaft 831 a located in the internal space of the toner supply path 83. The conveyance screw 831 supplies the toner supplied from the toner supply unit 82 into the guide unit 120 while conveying the toner in the left direction in FIG.

  In the lower part of FIG. 5, the guide unit 120 leads the carrier introduced through the first communication port 122 and the toner introduced through the third communication port 126 to the developing container 816. A communication port 124 is provided. The second communication port 124 is connected to the developer supply port 816 a of the developer container 816. That is, the internal space of the guide unit 120 and the internal space of the developing container 816 communicate with each other via the second communication port 124. 5 and 6, the flow direction of the carrier supplied from the carrier supply unit 90 is indicated by a dotted arrow, and the flow direction of the toner supplied from the toner supply unit 82 is indicated by a solid arrow.

  Here, the first communication port 122 is shifted from the position immediately above the developer supply port 816a of the developer container 816 to the downstream side in the toner transport direction. That is, the first communication port 122 and the second communication port 124 are arranged at positions that do not overlap in the direction of gravity. Here, the fact that they do not overlap in the direction of gravity means that when the parallel light is irradiated from the carrier supply path 97 side toward the first communication port 122, the shadow of the first communication port 122 appears on the second communication port 124. It means not projected.

  Between the first communication port 122 and the second communication port 124, a surface is formed in a planar shape, and the carrier introduced through the first communication port 122 is guided to the second communication port 124. A slope portion 128 is formed. As shown in FIG. 7, the angle θ of the slope portion 128 with respect to the horizontal plane is preferably set to 30 to 60 °, for example. As a result, the carrier flowing down from the carrier supply path 97 is smoothly guided to the second communication port 124 without stagnation. Note that the surface of the slope portion 128 may be formed in a curved surface shape (for example, a concave shape) instead of a planar shape.

  Incidentally, since the developer (toner and carrier) is stirred and circulated by the stirring members 813 and 814 in the developing container 816, the internal pressure in the developing container 816 increases. Since the internal pressure is released from the developer supply port 816a, the toner blows up into the guide portion 120. In the present embodiment, since the first communication port 122 and the second communication port 124 are arranged at positions where they do not overlap in the direction of gravity, even if toner is scattered in the guide portion 120 due to the release of the internal pressure, The toner can be prevented from entering the carrier supply path 97 connected to the first communication port 122 or adhering to the inner surface of the carrier supply path 97. Furthermore, frictional charging is prevented from occurring between the carrier that has flowed down the carrier supply path 97 and the toner scattered or adhered in the guide portion 120. In addition, since the slope portion 128 is formed, the carrier smoothly flows down toward the second communication port 124 without applying extra stress to the carrier that has fallen freely from the carrier supply path 97. be able to. Thus, the carrier flow area in the carrier supply path 97 is not restricted by the toner adhesion, that is, the carrier that has fallen freely is not hindered, and a certain amount of carrier can be supplied to the developing container 816 with high accuracy. . Therefore, the image forming apparatus 1 can maintain stable image quality.

Here, it is preferable that the carrier introduced through the first communication port 122 and the toner introduced through the third communication port 126 are not in direct contact. When the toner and the carrier are in direct contact with each other, frictional charging occurs, so that the charged toner easily adheres to the inner surface of the guide portion 120 and the like. This is because the supply of toner or carrier may be hindered by toner adhesion.
In the present embodiment, a direction regulating member 130 for regulating the flow direction of the carrier is provided on the surface of the slope portion 128. The direction regulating member 130 is a triangular roof-shaped member provided so as to cover a portion of the shaft 831 a of the conveying screw 831 that is located in the gravity direction of the first communication port 122. Since the direction regulating member 130 is provided, as shown in FIG. 6, the carrier introduced through the first communication port 122 is directed toward the peripheral portion of the second communication port 124 by the direction regulating member 130. Flow down (see dotted arrows). On the other hand, the toner conveyed to the inside of the direction regulating member 130 by the conveying screw 831 flows down to the vicinity of the center of the second communication port 124 (see solid arrow). In other words, the direction restricting member 130 has, for the second communication port 124, a region where the carrier introduced through the first communication port 122 is derived and a region where the toner conveyed by the conveyance screw 831 is derived. Divide into and. Therefore, since the carrier flowing down the carrier supply path 97 and the toner flowing down the toner supply path 83 are not in direct contact with each other, frictional charging is prevented from occurring, and toner or carrier supply is hindered by toner adhesion. Can be prevented.

  Further, the first communication port 122 is shifted from the position immediately above the developer supply port 816a of the developing container 816 to the downstream side in the toner transport direction. In other words, the first communication port 122 is provided on the downstream side of the second communication port 124 in the direction in which the toner is introduced via the third communication port 126. With this configuration, the toner introduced into the guide unit 120 via the third communication port 126 flows into the second communication port 124 before flowing down to the conveying screw 831 located in the gravity direction of the first communication port 122. It will flow down towards. Therefore, the direct contact between the carrier flowing down the carrier supply path 97 and the toner flowing down the toner supply path 83 can be suppressed, so that the toner or carrier supply is hindered by the adhesion of the toner. Can be prevented.

  Since the guide unit 120 has the above-described configuration, the timing at which the toner is supplied from the toner supply unit 82 and the timing at which the carrier is supplied from the carrier supply unit 90 are the same. Even when the timing at which the toner is introduced is the same as the timing at which the carrier is introduced into the guide portion 120, the carrier flowing down the carrier supply path 97 and the toner flowing down the toner supply path 83 are not in direct contact with each other. .

  FIG. 8 is a diagram illustrating a configuration example of the carrier accommodating portion 92. As shown in FIG. 8, the carrier accommodating portion 92 includes a carrier container 921 (carrier hopper), a measuring roller 922, a carrier regulating member 923, a remaining amount detecting sensor 924, and the like. The configuration of the carrier accommodating portion 92 shown in FIG. 8 is an example, and the carrier accommodating portion 92 can be configured as long as a predetermined amount of carriers can be accurately measured and the measured carrier can be dropped onto the carrier guide portion 93. There is no particular limitation.

  The carrier container 921 is formed in a substantially rectangular parallelepiped shape extending in the axial direction of the measuring roller 922. A substantially rectangular carrier supply port 921 c extending in the axial direction of the measuring roller 922 is formed in the lower portion of the carrier container 921. A measuring roller 922 is disposed below the carrier supply port 921c.

  The side wall 921d extending obliquely upward from one long side of the carrier supply port 921c is formed such that the end portion is separated from the peripheral surface of the measuring roller 922 by a predetermined distance. A carrier regulating member 923 as a layer thickness regulating member is attached to the side wall 921d.

  The carrier restricting member 923 is disposed on the diagonally upper side of the measuring roller 922 so as to be spaced apart from the measuring sleeve 922b by a predetermined distance. The separation distance between the carrier regulating member 923 and the measuring roller 922 is set to 0.1 to 1.0 mm, for example. The carrier restricting member 923 is a plate-like member formed of a magnetic material such as a stainless steel material, and extends in parallel with the measuring roller 922.

  Further, the side wall 921e extending obliquely upward from the other long side of the carrier supply port 921c is formed so that the end portion is close to the measuring roller 922. A rib 921f is continuously provided along the surface of the measuring roller 922 at the end of the side wall 921e. A tape-shaped magnetic seal 921g in which N poles and S poles are alternately formed in the width direction is attached to the inner surface of the rib 921f along the axial direction of the measuring roller 922. The rib 921f (magnetic seal 921g) and the measuring roller 922 are not in contact with each other, and the separation distance is set to 0.1 to 1.5 mm, for example. Since the carrier is restrained by the magnetic field formed by the magnetic seal 921g, it is held without free-falling.

  A carrier bottle 91 is connected to the upper portion of the carrier container 921 (see FIG. 3). When the remaining amount detection sensor 924 detects that the amount of carriers in the carrier container 921 is equal to or less than a predetermined amount, a certain amount of carriers is automatically supplied from the carrier bottle 91. For example, the control unit 100 performs opening / closing control of a shutter member (not shown) provided to be openable / closable at the supply port of the carrier bottle 91 based on a detection signal from the remaining amount detection sensor 924, whereby the carrier bottle 91 is controlled. A certain amount of carrier is automatically replenished. As a result, it is possible to prevent a problem that the carrier in the carrier container 921 becomes insufficient and a fixed amount of carrier cannot be supplied to the developing unit 81.

  The measuring roller 922 is a so-called magnet roller having a magnet body 922a that is fixed so as not to rotate and a cylindrical measuring sleeve 922b that is rotatably arranged around the magnet body 922a.

  The magnet body 922a has a plurality of magnetic poles N1, S1, and N2 extending in the axial direction of the measuring roller 922. The magnetic pole N1 is disposed corresponding to the layer thickness regulation position P3 where the carrier regulation member 923 regulates the layer thickness of the carrier. Here, since the carrier is attracted to the measuring sleeve 922b at the layer thickness regulation position P3, the layer thickness regulation position P3 and the carrier adsorption position P1 are the same. The magnetic pole N2 is arranged corresponding to the carrier detachment position P2 from which the carrier is detached and dropped. The magnetic pole S1 is disposed between the magnetic pole N1 and the magnetic pole N2.

  Here, the angle θ1 formed by the magnetic pole N1 and the vertical direction is preferably set to 45 ° ≦ θ1 ≦ 55 °. The angle θ2 formed by the magnetic pole N1 and the magnetic pole S1 is preferably set to 50 ° ≦ θ2 ≦ 70 °. The angle θ3 formed by the magnetic pole S1 and the magnetic pole N2 is preferably set to 50 ° ≦ θ3 ≦ 80 °. Thereby, carrier transportability and carrier peeling performance at the detachment position P2 can be ensured.

  When the magnetic poles N1, S1, and N2 are arranged in this manner, the following magnetic field is formed in the vicinity of the measuring sleeve 922b. That is, the end of the carrier regulating member 923 on the side of the measuring roller 922 is magnetized by the magnetic pole N1 to have a polarity (S pole) opposite to that of the magnetic pole N1. A magnetic field (lines of magnetic force) from the magnetic pole N1 toward the carrier restriction member 923 is formed at the layer thickness restriction position P3. A magnetic field that restrains the carrier to the measuring sleeve 922b is formed from the magnetic pole N1 and the magnetic pole S1 and the magnetic pole S1 and the magnetic pole N2 from the suction position P1 to the detachment position P2. In addition, a repulsive magnetic field (a magnetic field for separating the carrier from the measuring sleeve 922b) is formed by the magnetic pole N2 and the magnetic pole N1 on the downstream side in the carrier transport direction of the separation position P2.

  The carrier accommodated in the carrier container 921 is attracted to the magnetic pole N1 at the attracting position P1 and attracted to the measuring sleeve 922b. At this time, carrier spikes are formed in the normal direction of the measuring sleeve 922b along the magnetic field formed by the magnetic pole N1 and the carrier regulating member 923. While this state is maintained, the rising of the carrier passes through the layer thickness regulating position P3 as the measuring sleeve 922b rotates (counterclockwise). Panning is performed by a gap between the carrier regulating member 923 and the measuring sleeve 922b, and a carrier layer having a constant thickness is formed on the measuring sleeve 922b.

  The carrier whose layer thickness is regulated is restrained on the measuring sleeve 922b along the magnetic field formed by the magnetic pole N1 and the magnetic pole S1, and the magnetic field formed by the magnetic pole S1 and the magnetic pole N2, and is attracted as the measuring sleeve 922b rotates. It is transported from position P1 to desorption position P2.

  The carrier transported to the detachment position P2 is detached from the measuring sleeve 922b by its own weight. Since a repulsive magnetic field is formed at the detachment position P2 by the magnetic pole N2 and the magnetic pole N1, the carrier that has reached the detachment position P2 is easily detached from the measurement sleeve 922b without being restrained on the measurement sleeve 922b. Fall. Then, the carrier falls on a carrier guide portion 93 connected to the lower portion of the carrier accommodating portion 92 and is guided to a developing portion 81 as a supply destination via a carrier supply path 97 (see FIG. 3).

  FIG. 9 is a top view of the carrier guide portion 93. 10 is a cross-sectional view taken along the line XX in FIG. As shown in FIGS. 9 and 10, the carrier guide portion 93 includes a carrier receiving member 94 that receives the carrier that has dropped from the carrier accommodating portion 92, a carrier distribution member 95 that is connected to the lower portion of the carrier receiving member 94, and a carrier A support frame 96 or the like that supports the sorting member 95 so as to be able to rotate and slide is provided. The carrier receiving member 94, the carrier distribution member 95, and the support frame body 96 are molded bodies made of, for example, a resin material.

  In the present embodiment, the carrier distribution member 95 is rotated and slid to distribute the carrier to the plurality of developing units 81Y, 81M, 81C, 81K. The carrier may be distributed by sliding linearly relative to the support frame 96.

  The carrier receiving member 94 is a two-stage cylindrical member having an upper cylindrical portion 94A and a lower cylindrical portion 94B. The upper cylindrical portion 94A is formed in one region obtained by dividing the lower cylindrical portion 94B into four equal parts in plan view. A funnel-shaped upper carrier receiving portion 941 (hereinafter referred to as an upper receiving portion 941) having a diameter decreasing from the upper surface downward is formed from the upper cylindrical portion 94A to the lower cylindrical portion 94B. In addition, a carrier supply port 941a is connected to the lower portion of the upper receiving portion 941. The taper angle of the upper receiving portion 941 is set to an angle at which the carrier can roll (more than the repose angle (for example, 20 ° or more)). The carrier that has dropped to the upper receiving portion 941 falls to the carrier sorting member 95 via the carrier supply port 941a. Further, a peripheral wall 942 is formed on the lower peripheral edge of the lower cylindrical portion 94B, and the upper portion of the carrier distribution member 95 is loosely fitted inside the peripheral wall 942.

  The detailed structure of the carrier distribution member 95 is shown in FIGS. FIG. 11 is a top view of the carrier distribution member 95. FIG. 12 is an upper perspective view of the carrier distribution member 95. FIG. 13 is a bottom view of the carrier distribution member 95. FIG. 14 is a lower perspective view of the carrier distribution member 95.

  As shown in FIGS. 11 to 14, the carrier distribution member 95 is a substantially cylindrical member. In each region obtained by dividing the carrier distribution member 95 into four equal parts in plan view, funnel-shaped lower carrier receiving portions 95Y, 95M, 95C, and 95K (hereinafter referred to as lower receiving portions 95Y, 95M, 95C, 95K) are formed on the same circumference. In addition, carrier supply ports 95Ya, 95Ma, 95Ca, and 95Ka are connected to lower portions of the lower receiving portions 95Y, 95M, 95C, and 95K. The taper angles of the lower receiving portions 95Y, 95M, 95C, and 95K are set to an angle at which the carrier can roll (more than the repose angle (for example, 20 ° or more)), similarly to the upper receiving portion 941.

  A gear portion 951 connected to a gear transmission mechanism (not shown) is formed on the circumferential surface of the carrier distribution member 95 in the substantially vertical direction. A gear transmission mechanism (not shown) is connected to a motor (not shown). By driving a motor (not shown), the carrier distribution member 95 is rotated via a gear transmission mechanism (not shown) and the gear portion 951. Driving of the motor (not shown) is controlled by the control unit 100.

  One ends of carrier supply paths 97Y, 97M, 97C, and 97K are connected to the carrier supply ports 95Ya, 95Ma, 95Ca, and 95Ka (see FIG. 3). The carrier supply paths 97Y, 97M, 97C, and 97K are formed of flexible tubes having elasticity. The mounting angle of the carrier supply paths 97Y, 97M, 97C, and 97K is set to an angle at which the carrier can roll (more than the repose angle (for example, 20 ° or more)). The other ends of the carrier supply paths 97Y, 97M, 97C, and 97K are connected to the guide unit 120. On the lower surface of the carrier distribution member 95, for example, four hemispherical support legs 952 are formed projecting downward on the radially outer side of the carrier supply ports 95Ya, 95Ma, 95Ca, and 95Ka.

  The detailed structure of the support frame 96 is shown in FIGS. FIG. 15 is a top view of the support frame 96. FIG. 16 is an upper perspective view of the support frame 96. As shown in FIGS. 15 and 16, the support frame 96 is a substantially cylindrical member. On the bottom of the support frame 96, a mounting portion 961 for mounting the carrier distribution member 95 is formed in an annular shape. The lower part of the carrier distribution member 95 is loosely fitted inside the peripheral wall 963 of the support frame 96. That is, the carrier distribution member 95 is sandwiched from above and below in a rotatable state by the carrier receiving member 94 and the support frame 96.

  For example, a stepped portion 962 having a semi-cylindrical shape is provided horizontally at a position where the mounting portion 961 is divided into four equal parts. When the carrier distribution member 95 rotates, the height of the stepped portion 962 is set lower than the height of the supporting leg portion 952 so that the supporting leg portion 952 is in sliding contact with the placement portion 961.

  Here, the shape, size, position, and number of the support leg portions 952 and the step portions 962 are determined so that the support leg portions 952 get over the step portions 962 as the carrier distribution member 95 rotates. There is no particular limitation as long as vibration is generated. However, the support leg portion 952 and the step portion 962 are preferably formed point-symmetrically with respect to the center so that the carrier distributing member 95 is evenly vibrated.

  Further, when any of the lower receiving portions 95Y, 95M, 95C, and 95K of the carrier distribution member 95 is at the carrier drop position (a position corresponding to the carrier supply port 941a of the carrier receiving member 94), the step portion 962 is provided. However, it is preferable not to ride on the support leg 952. That is, the stepped portion 962 is preferably formed at a position corresponding to the middle between the two adjacent support leg portions 952 and 952. Thereby, the lower receiving portions 95Y, 95M, 95C, and 95K can receive the falling carrier in a stable state.

  Further, by setting the height of the stepped portion 962 high, the carrier distributing member 95 can be vibrated greatly. Furthermore, it is preferable that at least one of the support leg portion 952 and the step portion 962 is formed in a spherical shape so that the rotation operation of the carrier distribution member 95 is not hindered.

  At the time of carrier replenishment, the carrier sorting member 95 is rotated so that the lower receiving portions 95Y, 95M, 95C, and 95K are sequentially positioned at the carrier drop position. The carriers that have fallen to the lower receiving portions 95Y, 95M, 95C, and 95K are sent to the carrier supply paths 97Y, 97M, 97C, and 97K through the carrier supply ports 95Ya, 95Ma, 95Ca, and 95Ka. Then, the carrier flows down the carrier supply paths 97Y, 97M, 97C, and 97K, and together with the toner that flows down the toner supply paths 83Y, 83M, 83C, and 83K, the developing sections 81Y, 81M, and 81C through the guide section 120 , 81K (see FIG. 3).

  Specifically, the carrier is supplied according to the flowchart shown in FIG. FIG. 17 is a flowchart illustrating an example of the carrier supply process. The carrier supply process shown in FIG. 17 is realized by the CPU 101 executing a predetermined program stored in the ROM 102 when the image forming operation is started in the image forming apparatus 1, for example. With this carrier supply process, each block of the carrier supply unit 90 is controlled. 18 shows the operation of the measuring roller 922 of the carrier accommodating portion 92, and FIG. 19 shows the state of the carrier sorting member 95 in FIGS. 18 (a) to 18 (h).

  In the initial state, the lower receiving portion 95Y for Y of the carrier distribution member 95 is positioned at the carrier drop position, and the support frame 96 is positioned at an intermediate position between the adjacent support legs 952 and 952 of the carrier distribution member 95. It is assumed that the step portion 962 is located (see FIG. 19A).

  In step S101 in FIG. 17, the control unit 100 determines whether the carrier supply condition is satisfied. And the control part 100 waits until carrier supply conditions are satisfied, and when it determines with carrier supply conditions having been satisfied, it transfers to the process of step S102. The carrier supply condition is an index set in advance to determine that the developer in the developing unit 81 has deteriorated, and is, for example, the number of prints (for example, 1000 sheets) on which image formation has been performed. Carrier supply conditions are appropriately set according to development conditions and environmental conditions.

  In step S102, the control unit 100 rotates the measuring sleeve 922b to drop a predetermined amount of carrier onto the lower stage receiving portion 95Y for Y (for example, 5 seconds, see FIGS. 18A and 19A). The amount of the carrier supplied from the carrier supply unit 90 to the developing unit 81 is the amount of the carrier that has reached the separation position P2, that is, the separation distance G between the carrier regulating member 923 and the measuring sleeve 922b, and the amount of the measuring sleeve 922b. It is controlled by the amount of rotation. Since the separation distance between the carrier regulating member 923 and the measuring sleeve 922b is constant, by controlling the rotation amount of the measuring sleeve 922b with high accuracy, the fixed amount of carrier is dropped accurately and supplied to the developing unit 81. Can do. The dropped carrier rolls in the carrier supply path 97Y through the lower receiving portion 95Y and is supplied to the developing portion 81Y together with the toner. At this time, a part of the carrier (for example, about 1/10 of the supply amount) adheres to the surface of the lower receiving portion 95Y.

  In step S103, the control unit 100 rotates the carrier distribution member 95 (for example, 2 seconds, see FIGS. 18B and 19B). The rotation direction at this time (counterclockwise in FIG. 19B) is assumed to be normal rotation. Then, the lower receiving portion 95M for M is aligned with the carrier drop position.

  At this time, as shown in FIGS. 20A to 20C, the carrier distribution member 95 rotates and slides in a state where the support leg portion 952 is in contact with the placement portion 961 of the support frame 96. . Then, in the process in which the carrier distribution member 95 rotates, the support leg portion 952 gets over the stepped portion 962 located on the downstream side in the rotation direction. That is, since the carrier distribution member 95 moves up and down in a short time, the carrier distribution member 95 is vibrated. Therefore, the carrier adhering to the lower receiving portion 95Y for Y is shaken off by vibration, rolls on the carrier supply path 97Y, and is supplied to the developing portion 81Y together with the toner. A desired supply amount of carriers is supplied to the developing unit 81Y.

  Similarly, the carrier is supplied to the developing units 81M, 81C, 81K in the same manner as the carrier supply to the developing unit 81Y. That is, in step S104, the control unit 100 rotates the measuring sleeve 922b and drops a predetermined amount of carrier onto the lower M receiving portion 95M (for example, 5 seconds, see FIGS. 18C and 19C). ). The dropped carrier rolls in the carrier supply path 97M via the lower receiving portion 95M, and is supplied to the developing portion 81M together with the toner. In step S105, the control unit 100 causes the carrier sorting member 95 to rotate forward and aligns the C lower receiving portion 95C with the carrier drop position (for example, 2 seconds, see FIGS. 18D and 19D). ).

  Even if a part of the carrier (for example, about 1/10 of the supply amount) adheres to the surface of the lower receiving portion 95M, the carrier is shaken off by the vibration generated by the rotation operation of the carrier distributing member 95. A desired supply amount of carrier is supplied to the developing unit 81M.

  In step S106, the control unit 100 rotates the measuring sleeve 922b and drops a predetermined amount of carrier onto the lower C receiving portion 95C for C (for example, see FIG. 18 (e) and FIG. 19 (e) for 5 seconds). The dropped carrier rolls in the carrier supply path 97C via the lower receiving portion 95C and is supplied to the developing portion 81C together with the toner. In step S107, the control unit 100 causes the carrier sorting member 95 to rotate forward and aligns the lower receiving portion 95K for K with the carrier drop position (for example, 2 seconds, see FIGS. 18 (f) and 19 (f)). ).

  Even if a part of the carrier (for example, about 1/10 of the supply amount) is attached to the surface of the lower receiving portion 95C, the carrier is shaken off by the vibration generated by the rotation operation of the carrier distributing member 95. A desired supply amount of carrier is supplied to the developing section 81C.

  In step S108, the control unit 100 rotates the measuring sleeve 922b and drops a predetermined amount of carrier onto the lower K receiving portion 95K for K (see, for example, 5 seconds, FIGS. 18 (g) and 19 (g)). The dropped carrier rolls in the carrier supply path 97K through the lower receiving portion 95K, and is supplied to the developing portion 81K together with the toner. In step S109, the control unit 100 reverses the carrier distribution member 95, aligns the lower receiving portion 95Y for Y with the carrier drop position, and returns to the initial state (for example, 6 seconds, FIG. 18 (h), FIG. 19). (See (h)).

  Even if a part of the carrier (for example, about 1/10 of the supply amount) adheres to the surface of the lower receiving portion 95K, the carrier is shaken off by the vibration generated by the rotation operation of the carrier distributing member 95. A desired supply amount of carrier is supplied to the developing section 81K.

  Thereafter, the carrier is supplied every time the carrier supply condition is satisfied, for example, every 1000 images are formed. As described above, the carrier is supplied to each developing unit 81.

  In the developing unit 81, the excessive developer including the deteriorated carrier is discharged by the trickle mechanism with the supply of the carrier and the toner. As a result, the deteriorated carrier is replaced with a new carrier, so that the toner can be charged uniformly at all times, and a stable image quality can be realized regardless of the number of prints and environmental changes.

  As shown in FIG. 19, after the carrier is supplied to each of the lower receiving portions 95Y, 95M, 95C, and 95K, the support leg portion 952 gets over the step portion 962 at least once. Therefore, the carriers attached to the lower receiving portions 95Y, 95M, 95C, and 95K are reliably shaken off by vibration. After the carrier is supplied to all of the lower receiving portions 95Y, 95M, 95C, and 95K, the support leg portion 952 may only get over the step portion 962, but it adheres to the lower receiving portions 95Y, 95M, 95C, and 95K. In order to shake off the carrier, it is preferable to generate a vibration as much as possible.

[Effects of the present embodiment]
As described above in detail, in the present embodiment, the developing device 412 includes the developing container 816 that stores the two-component developer, and the toner supply unit 82 that supplies toner to the developing container 816 via the toner supply path 83. The carrier supply section 90 is provided independently of the toner supply section 82 and is connected to the carrier supply path 97 through a carrier supply path 97 extending in the direction of gravity and freely dropping the carrier and supplying the carrier to the developing container 816. A guide unit that has a first communication port 122 for introducing the carrier supplied from the carrier supply unit 90 and a second communication port 124 for leading the carrier to the developing container 816 and is arranged at the upper portion of the developing container 816. 120. The first communication port 122 and the second communication port 124 are arranged at positions that do not overlap in the direction of gravity. A slope portion 128 is formed between the first communication port 122 and the second communication port 124 to guide the carrier introduced through the first communication port 122 to the second communication port 124. .

  According to the present embodiment configured as described above, the first communication port 122 and the second communication port 124 are arranged at positions where they do not overlap in the direction of gravity, so that the internal pressure in the developing container 816 is the second pressure. Even if the communication port 124 is opened, the toner is prevented from scattering and adhering to the carrier supply path 97 connected to the first communication port 122. Furthermore, frictional charging is prevented from occurring between the carrier that has flowed down the carrier supply path 97 and the toner scattered or adhered in the guide portion 120. In addition, since the slope portion 128 is formed, the carrier smoothly flows down toward the second communication port 124 without applying extra stress to the carrier that has fallen freely from the carrier supply path 97. be able to. As a result, the flow of the carrier in the carrier supply path 97 is not restricted by the adhesion of the toner, that is, the transport of the carrier that has fallen freely is not hindered, and a certain amount of carrier can be supplied to the developing container 816 with high accuracy. , Can maintain stable image quality.

[Modification]
In the above embodiment, the example in which the toner supply path 83 and the carrier supply path 97 are connected to the guide unit 120 has been described, but the present invention is not limited to this. For example, only the carrier supply path 97 may be connected to the guide unit 120, and the toner supply path 83 may be connected to the developing container 816. In other words, the carrier that has fallen freely from the carrier supply path 97 and the toner that has flowed down through a different path (toner supply path 83) from the carrier may be separately supplied to the developing container 816. Even in this case, an effect similar to the effect in the above-described embodiment can be obtained.

  In the above embodiment, the example in which the first communication port 122 of the guide unit 120 is shifted from the position immediately above the developer supply port 816a of the developer container 816 to the downstream side in the toner transport direction has been described. As shown in FIGS. 21 and 22, the first communication port 122 is shifted from a position directly above the developer supply port 816a in a direction perpendicular to the toner conveyance direction in a plan view (the back side in FIG. 21). May be located. FIG. 21 is a diagram illustrating a configuration of the guide unit 140. 22 is a cross-sectional view taken along the line CC in FIG. In FIGS. 21 and 22, the same reference numerals as those shown in FIGS. 5 to 7 have the same functions, and therefore, redundant description is omitted here.

  The guide unit 140 has a first communication port 142 that is connected to the carrier supply path 97 and introduces the carrier supplied from the carrier supply unit 90 into the guide unit 140 at the upper part in FIG. That is, the internal space of the guide part 140 and the internal space of the carrier supply path 97 communicate with each other via the first communication port 142 formed in the upper part of the guide part 140 in FIG.

  The guide unit 140 has a third communication port 146 that is connected to a toner supply path 83 extending in the horizontal direction and that introduces toner supplied from the toner supply unit 82 into the guide unit 140 on the right side in FIG. That is, the internal space of the guide unit 140 and the internal space of the toner supply path 83 communicate with each other through the third communication port 146 formed in the right part of the guide unit 140 in FIG.

  The lower part in FIG. 21 of the guide part 140 is connected to the developer supply port 816a of the developer container 816. In the lower part of FIG. 21, the guide unit 140 leads the carrier introduced through the first communication port 142 and the toner introduced through the third communication port 146 to the developing container 816. A communication port 144 is provided. That is, the internal space of the guide part 140 and the internal space of the developing container 816 communicate with each other via the second communication port 144 formed in the lower part of the guide part 140 in FIG. 21 and 22, the flow direction of the carrier supplied from the carrier supply unit 90 is indicated by a dotted arrow, and the flow direction of the toner supplied from the toner supply unit 82 is indicated by a solid arrow.

  As shown in FIG. 22, in the guide unit 140, the carrier introduced through the first communication port 142 is inserted between the first communication port 142 and the second communication port 144. A slope portion 148 leading to 144 is formed. One end of the slope portion 148 is connected to the carrier supply path 97 via the first communication port 142.

  As shown in FIG. 22, the first communication port 142 and the second communication port 144 are arranged at positions that do not overlap in the direction of gravity. Here, the fact that they do not overlap in the direction of gravity means that when the parallel light is irradiated from the carrier supply path 97 side toward the first communication port 142, the shadow of the first communication port 142 appears on the second communication port 144. It means not projected.

  Since the first communication port 142 and the second communication port 144 are arranged at positions where they do not overlap in the direction of gravity, the first communication port 142 and the second communication port 144 are not affected even if toner is scattered in the guide unit 140 due to the release of the internal pressure in the developing container 816. It is possible to prevent the toner from entering the carrier supply path 97 connected to the one communication port 142 or adhering to the inner surface of the carrier supply path 97. Furthermore, frictional charging is prevented from occurring between the carrier that has flowed down the carrier supply path 97 and the toner scattered or adhered in the guide portion 140. In addition, since the slope portion 148 is formed between the first communication port 142 and the second communication port 144, no extra stress is applied to the carrier that has fallen freely from the carrier supply path 97. The carrier can smoothly flow down toward the second communication port 144. Thus, the carrier flow area in the carrier supply path 97 is not restricted by the toner adhesion, that is, the carrier that has fallen freely is not hindered, and a certain amount of carrier can be supplied to the developing container 816 with high accuracy. . Therefore, the image forming apparatus 1 can maintain stable image quality.

  In the vicinity of the exit of the slope portion 148 opposite to the first communication port 142, the carrier introduced through the first communication port 142 and the toner introduced through the third communication port 146 are present. A direction regulating member 150 that regulates the flow direction of the carrier is provided so as not to make direct contact. The direction regulating member 150 is a rectangular member provided so as to extend in the lower right direction in FIG. 22 to the vicinity of the shaft 831a of the conveying screw 831. Since the direction regulating member 150 is provided, as shown in FIG. 22, the carrier introduced through the first communication port 142 is directed toward the peripheral edge of the second communication port 144 by the direction regulating member 150. Flow down (see dotted arrows). On the other hand, the toner conveyed by the conveying screw 831 flows down to the vicinity of the central portion of the second communication port 144 (see solid line arrow). In other words, the direction regulating member 150 includes, for the second communication port 144, a region where the carrier introduced through the first communication port 142 is derived and a region where the toner conveyed by the conveyance screw 831 is derived. Divide into and. Therefore, since the carrier flowing down the carrier supply path 97 and the toner flowing down the toner supply path 83 are not in direct contact with each other, frictional charging is prevented from occurring, and toner or carrier supply is hindered by toner adhesion. Can be prevented.

  Since the guide unit 140 has the above-described configuration, the timing at which the toner is supplied from the toner supply unit 82 and the timing at which the carrier is supplied from the carrier supply unit 90 are the same. Even when the timing at which the toner is introduced and the timing at which the carrier is introduced into the guide portion 140 are the same, the carrier that has flowed down the carrier supply path 97 and the toner that has flowed down the toner supply path 83 are not in direct contact with each other. .

  In addition, each of the above-described embodiments is merely an example of actualization in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 81 Developing part 82 Toner supply part 83 Toner supply path 90 Carrier supply part 91 Carrier bottle 92 Carrier accommodating part 93 Carrier guide part 94 Carrier receiving member 95 Carrier distribution member (carrier distribution part)
95Y, 95M, 95C, 95K Lower carrier receiving part 96 Support frame (support frame part)
97 Carrier supply path 98 Excitation unit 100 Control unit 120, 140 Guide unit 122, 142 First communication port 124, 144 Second communication port 126, 146 Third communication port 128, 148 Slope unit 130, 150 Direction restriction Member 412 Developing device 816 Developing container 952 Support leg 962 Stepped portion

Claims (6)

A developing device that forms a toner image by developing an electrostatic latent image formed on a photoreceptor with a two-component developer composed of toner and a carrier,
A developer container containing the two-component developer;
A toner supply unit for supplying the toner to the developer container via a toner supply path;
A carrier supply unit that is provided independently of the toner supply unit and that freely drops the carrier through a carrier supply path extending in the direction of gravity and supplies the carrier to the developer container;
A first communication port that is connected to the carrier supply path and introduces the carrier supplied from the carrier supply unit; and a second communication port that leads the carrier to the developer container; A guide unit arranged in
With
The first communication port and the second communication port are arranged at positions where they do not overlap in the direction of gravity, and the first communication port and the second communication port are provided between the first communication port and the second communication port. A developing device characterized in that a slope portion for guiding the carrier introduced through the mouth to the second communication port is formed. The guide unit is connected to the toner supply path extending in a horizontal direction, and has a third communication port for introducing the toner supplied from the toner supply unit;
The second communication port leads the carrier introduced through the first communication port and the toner introduced through the third communication port to the developing container. The developing device according to claim 1.   The guide portion regulates the flow direction of the carrier so that the carrier introduced through the first communication port and the toner introduced through the third communication port do not come into direct contact with each other. The developing device according to claim 2, further comprising a direction restricting member.   The first communication port is provided on the downstream side of the second communication port in a direction in which the toner is introduced through the third communication port. The developing device according to 1.   5. The development according to claim 2, wherein a timing at which the toner is supplied from the toner supply unit and a timing at which the carrier is supplied from the carrier supply unit are the same. apparatus.   An image forming apparatus comprising the developing device according to claim 1.

Images