JP5942378B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus including a two-component developing type developing apparatus.

  In general, an electrophotographic image forming apparatus (printer, copying machine, facsimile, etc.) forms an electrostatic latent image by irradiating (exposing) laser light based on image data to a charged photoreceptor. By attaching toner to the electrostatic latent image, the electrostatic latent image is visualized to form a toner image. Then, the toner image is directly or indirectly transferred to the paper, and then fixed by heating and pressing 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 deteriorated developer in the developing device is periodically replaced. Further, since the degree of deterioration of the toner and the carrier in the developing device is different, a developing device that can supply the toner and the carrier independently has also been proposed (for example, Patent Documents 1 and 2).

Specifically, Patent Document 1 has a replenishment roller having a measurement recess formed in the peripheral surface, and a carrier supply that supplies the carrier put into the measurement recess to the developing unit by rotating the supply roller. A developing device having a section is disclosed.
Patent Document 2 discloses a developing device including a carrier supply unit that supplies a carrier to the developing unit by opening and closing a carrier replenishment shutter provided at the bottom of the carrier storage container.

JP 2005-250347 A Japanese Patent Laid-Open No. 10-63074

  In the developing device described in Patent Document 1, in order to supply a certain amount of carrier to the developing unit, it is necessary to prevent the carrier introduced into the measuring recess from leaking from the gap between the replenishing roller and the carrier passage. . However, when the sealing property between the replenishing roller and the carrier passage is enhanced, the replenishing roller slides with respect to the carrier passage, and thus a problem arises in terms of durability. That is, in the developing device described in Patent Document 1, it is difficult to achieve both the sealing performance that prevents leakage from the peripheral edge of the supply roller and the durability of the supply roller.

  In the developing device described in Patent Document 2, if the opening / closing function is disabled while the replenishment shutter is open, the carrier continues to flow out to the developing unit. Further, in the developing device described in Patent Document 2, the amount of carrier supply is controlled by the opening and closing time of the replenishment shutter. However, as the amount of carrier contained in the container changes, the bulk density changes and the time per hour changes. It is difficult to obtain high quantification because the amount of falling of the material changes.

  Thus, if a certain amount of carrier cannot be accurately supplied to the developing unit, the balance between the toner amount and the carrier amount in the developing unit may be lost, and the toner charge amount may become non-uniform, resulting in image quality. May decrease.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is capable of improving the durability of the carrier supply unit and forming an image having a developing device that can accurately supply a certain amount of carrier from the carrier supply unit to the developing unit. An object is to provide an apparatus.

An image forming apparatus reflecting one aspect of the present invention is a development that forms a visualized toner image by developing an electrostatic latent image formed on a photoreceptor with a developer composed of toner and a carrier by a two-component development method. An image forming apparatus comprising a unit,
A carrier supply unit for supplying the carrier to the developing unit; and a toner supply unit for supplying the toner to the developing unit,
A carrier container for accommodating the carrier;
A measuring sleeve that is rotatably supported in the carrier container and holds the carrier on a peripheral surface and conveys the carrier from an adsorption position to a desorption position;
A magnet body which is included in the measurement sleeve so as not to rotate, and forms a magnetic field so that the carrier is conveyed along with the rotation of the measurement sleeve;
Between the suction position and the desorption position, a layer thickness regulating member that is arranged to be opposed to the measurement sleeve by a predetermined distance and that trims the carrier held on the measurement sleeve;
A carrier guide unit that guides the carrier that is detached and dropped at the desorption position to the developing unit,
A controller that controls the amount of rotation of the metering sleeve so that a predetermined amount of the carrier reaches the detachment position;
A plurality of the developing units corresponding to different color components,
The carrier guide is
A plurality of carrier channels connected to each of the developing sections;
A gate selection unit that selects any one of the carrier flow paths as a supply destination of the carrier,
The gate selector is
A funnel member for receiving the carrier detached from the measuring sleeve;
A plurality of connection ports communicating with each of the carrier flow paths are formed on the same circumference, and have a funnel receiving member that rotatably supports the funnel member,
The funnel member rotates so that a flow-down port of the carrier formed in the funnel member coincides with any of the connection ports.
An image forming apparatus reflecting one aspect of the present invention is a development that forms a visualized toner image by developing an electrostatic latent image formed on a photoreceptor with a developer composed of toner and a carrier by a two-component development method. An image forming apparatus comprising a unit,
A carrier supply unit for supplying the carrier to the developing unit; and a toner supply unit for supplying the toner to the developing unit,
A carrier container for accommodating the carrier;
A measuring sleeve that is rotatably supported in the carrier container and holds the carrier on a peripheral surface and conveys the carrier from an adsorption position to a desorption position;
A magnet body which is included in the measurement sleeve so as not to rotate, and forms a magnetic field so that the carrier is conveyed along with the rotation of the measurement sleeve;
Between the suction position and the desorption position, a layer thickness regulating member that is arranged to be opposed to the measurement sleeve by a predetermined distance and that trims the carrier held on the measurement sleeve;
A carrier guide for guiding the carrier that is detached and dropped at the removal position to the developing unit;
A carrier holding member that is disposed opposite to and spaced from the measuring sleeve outside the carrier conveyance region extending from the adsorption position to the desorption position, and forms a magnetic field so as to hold the carrier; and
A first magnetic pole for forming a magnetic field for restraining the carrier in the carrier transport region extending from the attracting position to the desorbing position;
A second magnetic pole for forming a magnetic field for desorbing the carrier at the desorption position;
A third magnetic pole arranged corresponding to the layer thickness regulating position where the layer thickness regulating member is arranged,
A control unit is provided that controls a rotation amount of the measuring sleeve so that a predetermined amount of the carrier reaches the detachment position.

  According to the present invention, it is possible to realize an image forming apparatus including a developing device that can improve the durability of the carrier supply unit and can accurately supply a certain amount of carrier from the carrier supply unit to the developing unit.

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 the developing device which concerns on embodiment. It is a figure which shows an example of a image development part. It is a figure which shows the carrier measurement part which concerns on 1st Embodiment. It is a figure which shows the positional relationship of the measurement roller and carrier regulation member in 1st Embodiment. It is the figure which looked at the carrier guide part from the upper part. It is the figure which looked at the carrier guide part from diagonally upward. It is the figure which looked at the carrier guide part from diagonally downward. It is a flowchart which shows an example of a carrier supply process. It is a figure which shows the carrier measurement part which concerns on 2nd Embodiment. It is a figure which shows the positional relationship of the measurement roller and carrier regulation member in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
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 a control system of the image forming apparatus 1 according to the 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 C (cyan), M (magenta), Y (yellow), 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 (secondary transfer) to a sheet to form an image.
In the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of CMYK 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 procedure. Tandem system is adopted.

  As illustrated in FIGS. 1 and 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 conveyance 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 a sheet 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 (scanner) 12, 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 a 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 includes image forming units 41Y, 41M, 41C, and 41K, and an intermediate transfer unit for forming an image using each color toner of Y component, M component, C component, and K component based on input image data. 42 etc. are provided.

  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 image forming unit 41Y for the Y component are denoted by reference numerals, and the components 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, for example, an undercoat layer (UCL), a charge generation layer (CGL), a charge transport layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube). It is a negatively charged organic photoreceptor (OPC: Organic Photo-conductor) in which CTL (Charge Transport Layer) is sequentially laminated.

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. When the photosensitive drum 413 is irradiated with laser light, 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. Then, 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 contains a developer of each color component (for example, a two-component developer composed of a toner having a small particle diameter and a magnetic material), and causes the toner of each color component to adhere to the surface of the photosensitive drum 413. Thus, the electrostatic latent image is visualized 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 in sliding contact with the surface of the photosensitive drum 413. Transfer residual toner remaining on the surface of the photosensitive drum 413 after the primary transfer is scraped off and removed by a drum cleaning blade.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421 serving as an intermediate transfer member, a primary transfer roller 422, a secondary transfer roller 423, a driving roller 424, a driven roller 425, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is an endless belt, and is stretched around a driving roller 424 and a driven roller 425. The intermediate transfer belt 421 travels at a constant speed in the direction of arrow A by the rotation of the driving roller 424. When the intermediate transfer belt 421 is pressed against the photosensitive drum 413 by the primary transfer roller 422, the toner images of the respective colors are sequentially superimposed on the intermediate transfer belt 421 and primarily transferred. When the intermediate transfer belt 421 is pressed against the sheet S by the secondary transfer roller 423, the toner image primarily transferred to the intermediate transfer belt 421 is secondarily transferred to the sheet S.
The belt cleaning device 426 includes a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 421. Transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer is scraped off and removed by a belt cleaning blade.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the conveyed paper S at the nip portion. For the fixing unit 60, for example, an air separation type fixing device including a fixing unit 61 and an air separation unit 62 is applied.

  The transport unit 50 includes a paper feed unit 51, a transport mechanism 52, a paper discharge unit 53, and the like. In the two paper feed tray units 51a to 51c constituting the paper feed unit 51, paper (standard paper, special paper) S identified based on the basis weight, size, etc. of the paper is accommodated for each preset type. Is done.

The sheets S accommodated in the sheet feed tray units 51a to 51c are sent one by one from the top, and are conveyed to the image forming unit 40 by a conveyance mechanism 52 having a plurality of conveyance rollers such as a registration roller 52a. At this time, the registration portion where the registration rollers 52a are arranged 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 53 having a discharge roller 53a.

  FIG. 3 is a diagram illustrating a configuration of the developing device 412. As illustrated in FIG. 3, the developing device 412 includes a developing unit 81 that forms a toner image on the photosensitive drum 413, a toner supply unit 82 that supplies toner to the developing unit 81, and a carrier supply that supplies a carrier to the developing unit 81. Part 90 and the like. 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 developing devices 412Y, 412M, 412C, and 412K, and are connected to the developing units 81Y, 81M, 81C, and 81K through the toner flow paths 83Y, 83M, 83C, and 83K. Is done. A known technique can be applied to the toner supply unit 82.

  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 using the free fall movement of the carrier due to its own weight, the carrier supply unit 90 is disposed above all of the developing unit 81.

FIG. 4 is a diagram illustrating an 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 toner flowing down the toner channel 83 and the carrier flowing down the carrier channel 933 are mixed and supplied to the developing container 816 via the developer supply port 816a.

  Further, 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 positioned substantially above the conveying sleeve 812b and is opposed to the conveying sleeve 812b with 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 photoconductive drum 413 to visualize the electrostatic latent image on the photoconductive 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 showing the carrier weighing unit 92 according to the first embodiment, and FIG. 6 is a diagram showing the positional relationship between the weighing roller 922 and the carrier regulating member 923.
As shown in FIG. 5, the carrier weighing unit 92 includes a carrier container 921, a weighing roller 922, a carrier regulating member 923, a remaining amount detection sensor 924, and the like.

  The carrier container 921 is formed in a substantially rectangular parallelepiped shape extending in the axial direction of the measuring roller 922, and has a substantially upper half carrier accommodating portion 921a (carrier hopper) and a substantially lower half roller accommodating portion 921b. A substantially rectangular carrier supply port 921c extending in the axial direction of the measuring roller 922 is formed in the lower portion of the carrier accommodating portion 921a. 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 oppositely and diagonally above the measuring roller 922, with a predetermined distance G from the measuring sleeve 922b. The separation distance G 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 part of the carrier container 921. When the remaining amount detection sensor 924 detects that the amount of carriers in the carrier accommodating portion 921a is equal to or less than a predetermined amount, a certain amount of carriers is automatically supplied from the carrier bottle 91. ing. For example, a shutter member (not shown) that can be opened and closed is provided at the supply port of the carrier bottle 91, and the control unit 100 controls the opening and closing of the shutter member based on the detection signal from the remaining amount detection sensor 924. .

That is, the carrier supply unit 90 includes a carrier container 921 based on the detection result of the remaining amount detection sensor 924 (carrier amount detection unit) that detects the amount of the carrier accommodated in the carrier container 921 and the remaining amount detection sensor 924. Are provided with a carrier replenishment unit (carrier bottle 91, control unit 100) for replenishing a predetermined amount of carrier.
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.

  A carrier guide 93 is connected to the lower part of the carrier container 921. The carrier weighed by the carrier weighing unit 92 falls to the carrier guide unit 93 and is guided to the developing unit 81 as a supply destination (see FIG. 3).

  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, it is desirable that the angle θ1 (see FIG. 6) formed by the perpendicular direction of the magnetic pole N1 is set to 45 ° ≦ θ1 ≦ 55 °. Further, it is desirable that the angle θ2 (see FIG. 6) formed by the magnetic pole N1 and the magnetic pole S1 is set to 50 ° ≦ θ2 ≦ 70 °. Further, it is desirable that the angle θ3 (see FIG. 6) formed by the magnetic pole S1 and the magnetic pole N2 is 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 (separation distance G) 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 and falls to the carrier guide portion 93. Since a repulsive magnetic field is formed by the magnetic pole N2 and the magnetic pole N1 at the detachment position P2, 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.

As described above, the magnet body 922a according to the first embodiment has the magnetic poles N1, S1, and N2 that form a magnetic field for restraining the carrier in the carrier transport region from the attracting position P1 to the desorbing position P2. Magnetic poles), magnetic poles N1 and N2 (second magnetic pole) that form a magnetic field (repulsive magnetic field) for detaching carriers at the detaching position P2, and a carrier regulating member 923 (layer thickness regulating member) are arranged. And a magnetic pole N1 (third magnetic pole) arranged corresponding to the layer thickness regulating position P3.
Thereby, a certain amount of carriers can be reliably transported to the detachment position P2 and can be easily detached. Accordingly, a certain amount of carrier can be easily supplied to the developing unit 81.

7 is a view of the carrier guide portion 93 as viewed from above, FIG. 8 is a view of the carrier guide portion 93 as viewed from obliquely above, and FIG. 9 is a view of the carrier guide portion 93 as viewed from obliquely below.
As shown in FIGS. 7 to 9, the carrier guide portion 93 includes a funnel member 931 that receives the carrier that has fallen from the carrier weighing portion 92, a funnel receiving member 932 that rotatably supports the funnel member 931, and a carrier from which the carrier flows down. A flow path 933 and the like are provided.

  In the funnel receiving member 932, four carrier circulation ports 932a (Y), 932a (M), 932a (C), and 932a (K) and one carrier receiving portion 932a (H) are formed on the same circumference. The Carrier flow paths 933Y, 933M, 933C, and 933K are connected to the carrier circulation ports 932a (Y), 932a (M), 932a (C), and 932a (K), respectively. The carrier receiving portion 932a (H) is closed, and prevents the carrier from flowing out by mistake.

  The funnel receiving member 932 has a rotation shaft 932b that rotatably supports the funnel member 931 at the center. The rotating shaft 932b is connected to a motor (not shown), and the funnel member 931 rotates along the inner peripheral surface of the funnel receiving member 932 by rotating the motor.

  At the bottom of the funnel member 931, the carrier flow port 932 a (Y), 932 a (M), 932 a (C), 932 a (K) of the funnel receiving member 932, or the carrier receiving portion 932 a ( A carrier supply port 931a corresponding to any one of (H) is formed. The inner surface of the funnel member 931 is formed in a tapered shape toward the carrier supply port 931a. This taper angle is set to an angle at which the carrier can roll (at least an angle of repose (for example, 20 °) or more).

The carrier supply channel 933 is configured by an elastic flexible tube. The mounting angle of the carrier supply channel 933 is set to an angle at which the carrier can roll (at least an angle of repose (for example, 20 °)).
One end of each of the carrier supply channels 933Y, 933M, 933C, and 933K is connected to the carrier flow port 932a (Y), 932a (M), 932a (C), and 932a (K) of the funnel receiving member 932, respectively. The other ends of the carrier supply channels 933Y, 933M, 933C, and 933K are connected to a supply port (not shown) formed in the middle of the toner channel 83.

  The carrier that has fallen from the carrier measuring unit 92 rolls on the tapered inner surface of the funnel member 931 and is collected at the carrier supply port 931a. The carrier flows down the selected carrier flow path 933 and is supplied to the developing unit 81 together with the toner flowing down the toner flow path 83.

When supplying the carrier to the developing unit 81, the carrier replenishing port 931a of the funnel member 931 is made to coincide with one of the carrier circulation ports 932a (Y), 932a (M), 932a (C), and 932a (K). In addition, the funnel member 931 is rotated. On the other hand, when the carrier is not supplied to the developing unit 81, the funnel member 931 is rotated (home position) so that the carrier supply port 931a of the funnel member 931 is positioned at the carrier receiving portion 932a (H).
Specifically, the carrier is supplied according to the flowchart shown in FIG.

  FIG. 10 is a flowchart illustrating an example of the carrier supply process. The carrier supply process shown in FIG. 10 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.

In step S101, the control unit 100 determines whether or not a 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 funnel member 931 so that the carrier supply port 931a is aligned with the Y carrier circulation port 933a (Y).
In step S103, the control unit 100 rotates the measuring sleeve 922b to drop a predetermined amount of carrier onto the carrier guide unit 93 (funnel member 931). The dropped carrier rolls in the carrier flow path 933Y via the funnel member 931, and is supplied to the developing unit 81Y together with the toner.

  Here, 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 removal position P2, that is, the separation distance G between the carrier regulating member 923 and the measuring sleeve 922b, and the measurement. It is controlled by the amount of rotation of the sleeve 922b. 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.

  Similarly to steps S102 and S103, carrier supply to the developing unit 81M (steps S104 and S105), carrier supply to the developing unit 81C (steps S106 and S107), and carrier supply to the developing unit 81K (step S108). , S109) is performed.

When the supply of the carrier to the developing units 81Y, 81M, 81C, 81K is completed, in step S110, the control unit 100 rotates the funnel member 931 and sets the carrier supply port 931a to the carrier receiving unit 933a (H) which is the home position. Return to.
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 described above, the image forming apparatus 1 is rotatably supported in the carrier container 921, holds the carrier on the peripheral surface, and conveys it from the suction position P1 to the detachment position P3, and the measurement sleeve 922b. A predetermined distance G from the measuring sleeve 922b is included between the magnet body 922a which is included in a non-rotatable manner and forms a magnetic field so that the carrier is transported as the measuring sleeve 922b rotates, and the attracting position P1 and the detaching position P2. A carrier restricting member 923 (layer thickness restricting member) that is disposed oppositely and spaced from each other and that cuts the carrier held on the measuring sleeve 922b and a carrier that is detached and dropped at the detaching position P2 are guided to the developing unit 81. The amount of rotation of the metering sleeve 922b is controlled so that a predetermined amount of carriers reach the detachment position P2. And a control unit 100 which, a.

As a result, with the rotation of the measuring sleeve 922b, the carrier that has been trimmed to a constant thickness at the layer thickness regulation position P3 is conveyed, and a certain amount of carrier that has reached the detachment position P2 is accurately supplied to the developing unit 81. .
In addition, since the carrier is magnetized and conveyed by the magnet body 922a using the magnetization characteristics of the carrier, the carrier does not leak from the peripheral edge of the measuring roller 922. Further, since the carrier is not dropped from the carrier container 921 as it is, even if the amount of carrier (bulk density) in the carrier container 921 changes, a certain amount of carrier can be supplied to the developing unit 81.

  In addition, since the magnet body 922a maintains a magnetic force semipermanently, the carrier supply unit 90 has high durability. Further, since there is no part that gives mechanical stress to the carrier other than the carrier regulating member 923 in the carrier measuring unit 92, the soundness of the carrier is maintained.

In this way, the developing device 412 that can improve the durability of the carrier supply unit 90 and can accurately supply a certain amount of carrier from the carrier supply unit 90 to the developing unit 81 is realized. Further, in the image forming apparatus 1, since the toner is uniformly charged by the developing device 412, the stability of the image quality is remarkably improved.
Furthermore, since it is not necessary to periodically replace the developer by a service person, machine downtime can be reduced.

Further, the image forming apparatus 1 includes a gate selection unit (funnel member 931 and funnel receiving member 932) that selects any one of the carrier flow paths 933Y, 933M, 933C, and 933K as a carrier supply destination.
As a result, it is possible to supply the carrier to the plurality of developing units 81 simply by providing one carrier supply unit 90, so that the apparatus configuration is simplified.

In the image forming apparatus 1, the carrier supply unit 90 is positioned above the developing unit 81, and the carrier detached from the measuring sleeve 922 b flows down the carrier guide unit 93 by a free fall movement.
Thereby, since it is not necessary to separately provide a member (such as a transport screw) for transporting the carrier, the apparatus configuration is further simplified.

[Second Embodiment]
FIG. 11 is a diagram illustrating a carrier weighing unit 92 according to the second embodiment, and FIG. 12 is a diagram illustrating a positional relationship between the weighing roller 922 and the carrier regulating member 923.
The second embodiment is different from the first embodiment in the configuration of the carrier weighing unit 92, and the other configurations are the same. Therefore, only the carrier weighing unit 92 will be described. Further, the same or corresponding components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be simplified.

  As shown in FIG. 11, the carrier weighing unit 92 includes a carrier container 925, a weighing roller 922, a carrier regulating member 923, a remaining amount detection sensor 924, an impeller 926, and the like.

The carrier container 925 is formed in a substantially rectangular parallelepiped shape extending in the axial direction of the measuring roller 922, and includes a carrier housing part 925a (carrier hopper) in a substantially right half part and a roller housing part 925b in a substantially lower half part.
An impeller 926 is rotatably disposed in the carrier accommodating portion 925a. The right side of the carrier accommodating portion 925a is closed by the measuring roller 922 (except for the layer thickness regulation position P3). The carrier accommodated in the carrier accommodating portion 925a is efficiently conveyed to the measuring roller 922 by the impeller 926.

A side wall 925c extending obliquely upward from the bottom is formed in the carrier container 925, and a carrier regulating member 923 as a layer thickness regulating member is attached to the side wall 925c.
The carrier restricting member 923 is disposed oppositely and obliquely below the measuring roller 922, with a predetermined distance G from the measuring sleeve 922b. The separation distance G 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, a carrier bottle 91 is connected to the upper portion of the carrier container 925 (carrier accommodating portion 925a). Then, when the remaining amount detection sensor 924 detects that the amount of carriers in the carrier accommodating portion 925a is equal to or less than a predetermined amount, a certain amount of carriers is automatically supplied from the carrier bottle 91. ing.

  Moreover, the lower part of the roller accommodating part 925b is open | released and the carrier guide part 93 is connected so that the carrier conveyed by the measurement sleeve 922b can fall. The carrier weighed by the carrier weighing unit 92 falls to the carrier guide unit 93 and is guided to the developing unit 81 as a supply destination.

  The measuring roller 922 is a so-called magnet roller in which a cylindrical measuring sleeve 922b is rotatably attached to the outer periphery of a magnet body 922a fixed so as not to rotate.

  The magnet body 922a has a plurality of magnetic poles S1, N1, and S2 extending in the axial direction of the measuring roller 922.

  The magnetic pole S1 is disposed corresponding to the suction position P1 for attracting the carrier to the measuring sleeve 922b. 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. The magnetic pole S1 is arranged corresponding to the carrier detachment position P2 from which the carrier is detached and dropped.

Here, the angle θ1 (see FIG. 12) formed by the magnetic pole S1 and the magnetic pole N1 is preferably set to 35 ° ≦ θ1 ≦ 45 °. The angle θ2 (see FIG. 12) formed by the magnetic pole N1 and the magnetic pole S2 is desirably set to 35 ° ≦ θ2 ≦ 45 °. Further, it is desirable that an angle θ3 (see FIG. 12) formed by the magnetic pole S1 and the horizontal direction is set to 80 ° ≦ θ3 ≦ 90 °.
Thereby, carrier transportability and carrier peeling performance at the detachment position P2 can be ensured.

When the magnetic poles S1, N1, and S2 are thus arranged, 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 constrains the carrier to the measuring sleeve 922b is formed from the magnetic pole S1 and the magnetic pole N1, and the magnetic pole N1 and the magnetic pole S2 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 S2 and the magnetic pole S1 on the downstream side in the carrier transport direction of the separation position P2.

The carrier accommodated in the carrier container 925 is attracted to the magnetic pole S1 at the attracting position P1 and attracted to the measuring sleeve 922b. The attracted carrier is restrained on the measuring sleeve 922b along the magnetic field formed by the magnetic pole S1 and the magnetic pole N1, and is transported from the attracting position P1 to the layer thickness regulating position P3 as the measuring sleeve 922b rotates.
At the layer thickness regulating position P3, 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 (separation distance G) 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 S2, and is transported from the layer thickness regulating position P3 to the separation position P2 as the measuring sleeve 922b rotates. The

  The carrier transported to the detachment position P2 is detached from the measuring sleeve 922b by its own weight and falls to the carrier guide portion 93. Since a repulsive magnetic field is formed by the magnetic pole S2 and the magnetic pole S1 at the detachment position P2, 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.

As described above, the magnet body 922a according to the second embodiment has the magnetic poles S1, N1, and S2 that form the magnetic field for restraining the carrier in the carrier transport region from the attracting position P1 to the desorbing position P2. Magnetic poles), magnetic poles S1 and S2 (second magnetic pole) that form a magnetic field (repulsive magnetic field) for detaching carriers at the detaching position P2, and a carrier regulating member 923 (layer thickness regulating member) are arranged. And a magnetic pole N1 (third magnetic pole) arranged corresponding to the layer thickness regulating position P3.
Thereby, a certain amount of carriers can be reliably transported to the detachment position P2 and can be easily detached. Accordingly, a certain amount of carrier can be easily supplied to the developing unit 81.

  Further, as in the first embodiment, the developing device 412 that can improve the durability of the carrier supply unit 90 and can accurately supply a certain amount of carrier from the carrier supply unit 90 to the developing unit 81 is realized. Further, in the image forming apparatus 1, since the toner is uniformly charged by the developing device 412, the stability of the image quality is remarkably improved. Furthermore, since it is not necessary to periodically replace the developer by a service person, machine downtime can be reduced.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be changed without departing from the gist thereof.
For example, the configuration of the magnetic poles of the magnet body 922a of the measuring roller 922 is not limited to the configuration shown in the above embodiment.
In the above embodiment, a color image forming apparatus including a plurality of developing devices 412Y, 412M, 412C, and 412K has been exemplified. However, the present invention is also applied to a monochrome image forming apparatus including only one developing device. be able to. In this case, a gate selection unit (funnel members 931 and 932) for selecting a carrier supply destination is not necessary.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Operation display part 30 Image processing part 40 Image forming part 50 Conveying part 60 Fixing part 81 Developing part 82 Toner supply part 83 Toner flow path 90 Carrier supply part 91 Carrier bottle 92 Carrier measurement part 921 Carrier Container 922 Measuring roller 922a Magnet body 922b Measuring sleeve 923 Carrier regulating member 924 Remaining amount detection sensor 93 Carrier guide unit 100 Control unit

Claims (5)

  An image forming apparatus including a developing unit that forms a visualized toner image by developing an electrostatic latent image formed on a photoconductor with a developer composed of toner and a carrier by a two-component development method,
  A carrier supply unit for supplying the carrier to the developing unit; and a toner supply unit for supplying the toner to the developing unit,
  A carrier container for accommodating the carrier;
  A measuring sleeve that is rotatably supported in the carrier container and holds the carrier on a peripheral surface and conveys the carrier from an adsorption position to a desorption position;
  A magnet body which is included in the measurement sleeve so as not to rotate, and forms a magnetic field so that the carrier is conveyed along with the rotation of the measurement sleeve;
  Between the suction position and the desorption position, a layer thickness regulating member that is arranged to be opposed to the measurement sleeve by a predetermined distance and that trims the carrier held on the measurement sleeve;
  A carrier guide unit that guides the carrier that is detached and dropped at the desorption position to the developing unit,
  A controller that controls the amount of rotation of the metering sleeve so that a predetermined amount of the carrier reaches the detachment position;
  A plurality of the developing units corresponding to different color components,
  The carrier guide is
  A plurality of carrier channels connected to each of the developing sections;
  A gate selection unit that selects any one of the carrier flow paths as a supply destination of the carrier,
  The gate selector is
  A funnel member for receiving the carrier detached from the measuring sleeve;
  A plurality of connection ports communicating with each of the carrier flow paths are formed on the same circumference, and have a funnel receiving member that rotatably supports the funnel member,
  2. The image forming apparatus according to claim 1, wherein the funnel member rotates so that a flow-down port of the carrier formed in the funnel member coincides with one of the connection ports.
A first magnetic pole for forming a magnetic field for restraining the carrier in the carrier transport region extending from the attracting position to the desorbing position;
A second magnetic pole for forming a magnetic field for desorbing the carrier at the desorption position;
The image forming apparatus according to claim 1, further comprising: a third magnetic pole disposed corresponding to a layer thickness regulating position where the layer thickness regulating member is arranged. The carrier supply unit is positioned above the developing unit;
The image forming apparatus according to claim 1 or 2 wherein the carrier desorbed from said metering sleeve, characterized in that flow down the carrier guide portion with a free-falling movement. A carrier amount detector for detecting the amount of the carrier contained in the carrier container;
The image according to any one of claims 1 to 3 , further comprising: a carrier replenishment unit that replenishes the carrier container with a predetermined amount of the carrier based on a detection result by the carrier amount detection unit. Forming equipment. An image forming apparatus including a developing unit that forms a visualized toner image by developing an electrostatic latent image formed on a photoconductor with a developer composed of toner and a carrier by a two-component development method,
A carrier supply unit for supplying the carrier to the developing unit; and a toner supply unit for supplying the toner to the developing unit,
A carrier container for accommodating the carrier;
A measuring sleeve that is rotatably supported in the carrier container and holds the carrier on a peripheral surface and conveys the carrier from an adsorption position to a desorption position;
A magnet body which is included in the measurement sleeve so as not to rotate, and forms a magnetic field so that the carrier is conveyed along with the rotation of the measurement sleeve;
Between the suction position and the desorption position, a layer thickness regulating member that is arranged to be opposed to the measurement sleeve by a predetermined distance and that trims the carrier held on the measurement sleeve;
A carrier guide for guiding the carrier that is detached and dropped at the removal position to the developing unit;
A carrier holding member that is disposed opposite to and spaced from the measuring sleeve outside the carrier conveyance region extending from the adsorption position to the desorption position, and forms a magnetic field so as to hold the carrier; and
A first magnetic pole for forming a magnetic field for restraining the carrier in the carrier transport region extending from the attracting position to the desorbing position;
A second magnetic pole for forming a magnetic field for desorbing the carrier at the desorption position;
A third magnetic pole arranged corresponding to the layer thickness regulating position where the layer thickness regulating member is arranged,
An image forming apparatus comprising: a control unit configured to control a rotation amount of the measuring sleeve so that a predetermined amount of the carrier reaches the detachment position.

Images