JP2021056393A - Developing device and image forming apparatus - Google Patents

Abstract

To provide a developing device that can increase the accuracy in detecting the bulk of developer, and an image forming apparatus.SOLUTION: A developing device is a developing device that attaches toner to an electrostatic latent image formed on a surface of an image carrier to visualize the electrostatic latent image and thereby form a toner image, and comprises: a developer storage unit that has a metal part formed of metal and a non-metal part formed of non-metal and stores developer including toner; and a developer bulk detection unit that is arranged in the non-metal part and detects the bulk of the developer in the developer storage unit.SELECTED DRAWING: Figure 3

Description

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

Generally, in an image forming apparatus (printer, copier, facsimile, etc.) using electrophotographic process technology, laser light based on image data irradiates (exposes) a uniformly charged photoconductor (for example, a photosensitive drum). ), An electrostatic latent image is formed on the surface of the photoconductor. Then, the toner (developer) is supplied from the developing device to the photoconductor on which the electrostatic latent image is formed, so that the electrostatic latent image is visualized and the toner image is formed. The toner image is transferred directly or indirectly to the paper via an intermediate transfer body, and then heated and pressed by a fixing device to form an image on the paper.

In the two-component developing method in which toner and carriers are used as the main components of the developing agent, carriers are mixed with the toner in the toner cartridge at a constant ratio in order to suppress deterioration of the developing agent, and the carriers are newly mixed at the same time as the toner is supplied. A trickle developing method is known, which is a technique for keeping the bulk (liquid level) of the developer in the developing device constant by supplying carriers into the developing device and discharging the deteriorated carriers from the developing device. (See, for example, Patent Document 1).

Further, there is known a developer bulk detection unit that detects the bulk of the amount of the developer in the developing apparatus (see, for example, Patent Document 2).

Further, a developer stirring path is provided in the developing apparatus. A stirring screw is arranged along the axial direction in the developer stirring path. By rotating the stirring screw, the developer is conveyed in one direction while being agitated, and the toner contained in the developer and the carrier are in frictional contact with each other and are charged to opposite polarities. This frictional contact raises the temperature of the developing device. This temperature rise becomes remarkable as the image formation process is accelerated. However, it is necessary to suppress the temperature rise of the developing apparatus because the deterioration due to the stress of the developing agent progresses.

In order to suppress the temperature rise of the developing device, it is conceivable to mold the developing agent accommodating portion of the developing device with a metal material such as aluminum having high thermal conductivity. For example, Patent Document 3 describes a developing device having a developing agent accommodating portion molded from a metal material.

Japanese Unexamined Patent Publication No. 2019-28221 International Publication No. 2004/0893965 Japanese Unexamined Patent Publication No. 03-160482

By the way, in the developing apparatus described in Patent Document 3, it is necessary to provide a developing agent bulk detecting portion for detecting the bulk of the developing agent in the developing apparatus in a developer accommodating portion (case) formed of a metal material. .. Since the developer accommodating portion formed of a metal material has an adverse effect when detecting the bulk of the developer by, for example, the magnetic permeability, there is a problem that the accuracy of detecting the volume of the developer is lowered.

An object of the present invention is to provide a developing device and an image forming device capable of improving the detection accuracy of the bulk of a developing agent while suppressing a temperature rise of the developing device.

The developing apparatus according to the present invention for achieving the above object is
In a developing device that visualizes an electrostatic latent image and forms a toner image by adhering toner to an electrostatic latent image formed on the surface of the image carrier.
A developer accommodating portion having a metal portion made of metal and a non-metal portion made of non-metal and accommodating a developer containing the toner, and a developer accommodating portion.
A developer bulk detection unit, which is arranged in the non-metal portion and detects the bulk of the developer in the developer accommodating portion,
To be equipped.

The image forming apparatus according to the present invention includes the above-mentioned developing apparatus, and forms a toner image on the image carrier by the developing apparatus.

According to the developing apparatus of the present invention, it is possible to improve the accuracy of detecting the bulk of the developing agent while suppressing the temperature rise of the developing apparatus.

It is a figure which shows the whole structure of the image forming apparatus in embodiment of this invention. It is a top view which shows typically an example of the developing apparatus in embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line AA of the developing apparatus shown in FIG. It is a partially enlarged sectional view of FIG. FIG. 2 is a cross-sectional view taken along the line BB of the developing apparatus shown in FIG. It is a top view which shows typically the developing apparatus which concerns on a modification. FIG. 6 is a sectional view taken along line CC of the developing apparatus shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention.
The image forming apparatus 1 shown in FIG. 1 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. In the image forming apparatus 1, photosensitive drums 413 corresponding to the four colors of CMYK are arranged in series in the traveling direction (vertical direction) of the intermediate transfer belt 421, and each color toner image is sequentially transferred to the intermediate transfer belt 421 in a single procedure. The vertical tandem method is adopted.

That is, the image forming apparatus 1 transfers (primary transfer) the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photosensitive drum 413 to the intermediate transfer belt 421. Then, after superimposing the toner images of four colors on the intermediate transfer belt 421, the image is formed by transferring (secondary transfer) to the paper S.

As shown in FIG. 1, 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 conveying unit 50, a fixing unit 60, and a control unit 100.

The control unit 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU reads a program according to the processing content from the ROM, develops it in the RAM, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the expanded program. At this time, various data stored in the storage unit (not shown) are referred to. The storage unit (not shown) is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

Further, the control unit 100 is connected to an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via a communication unit (not shown). Send and receive various data. The control unit 100 receives, for example, image data transmitted from an external device, and causes the paper S to form an image based on the image data (input image data). The communication unit (not shown) is composed of a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.
The automatic document feeding device 11 conveys the documents placed on the document tray by the conveying mechanism and sends them out to the document image scanning device 12. The automatic document feeding device 11 makes it possible to continuously read images (including both sides) of a large number of documents placed on a document tray. The document image scanning device 12 optically scans the document conveyed on the contact glass from the automatic document feeding device 11 or the document placed on the contact glass, and the reflected light from the document is a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and the original image is read. The image scanning unit 10 generates input image data based on the scanning result by the document image scanning device 12. The image processing unit 30 performs predetermined image processing on the input image data.

The operation display unit 20 is composed of, 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 according to 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 or the like that performs digital image processing according to initial settings or user settings on the input image data. 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 (image density control). Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

The image forming unit 40 includes an image forming unit 41, an intermediate transfer unit 42, and the like for forming an image with each colored toner of the Y component, the M component, the C component, and the K component based on the input image data. The writing range of the image formed by the image forming unit 40 is preset.

The image forming unit 41 is composed of four image forming units 41Y, 41M, 41C, and 41K for the Y component, the M component, the C component, and the K component. Since the image forming units 41Y, 41M, 41C, and 41K have the same configuration, common components are indicated by the same reference numerals for convenience of illustration and description, and when distinguishing between them, the reference numerals are Y, M, and C. , Or K will be added. In FIG. 1, reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals for the other components of the 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: Under Coat Layer), a charge generation layer (CGL: Charge Generation Layer), and a charge transport layer (CTL) on the peripheral surface of a conductive cylindrical body (aluminum tube) made of aluminum. : Charge Transport Layer) is sequentially laminated to be a negatively charged organic photo-conductor (OPC).
The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, a phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and is exposed by an exposure apparatus 411 to generate a pair of positive and negative charges. The charge transport layer is composed of a hole transport material (electron donating nitrogen-containing compound) 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 charging device 414 is composed of, for example, a corona discharge generator such as a scorotron charging device or a corotron charging device. The charging device 414 uniformly charges the surface of the photosensitive drum 413 to a negative electrode by corona discharge.

The exposure device 411 is composed of, for example, a semiconductor laser. The exposure device 411 irradiates the photosensitive drum 413 with a laser beam corresponding to an image of each color component. The surface charge (negative charge) of the photosensitive drum 413 is neutralized by transporting the positive charge generated in the charge generation layer of the photosensitive drum 413 to the surface of the charge transport layer. As a result, an electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to the potential difference from the surroundings.

The developing apparatus 412 contains a developing agent for each color component (a two-component developing agent composed of a toner having a small particle size and a carrier), and electrostatically latent by adhering the toner for each color component to the surface of the photosensitive drum 413. The image is visualized to form a toner image. Specifically, a development bias voltage is applied to the developer carrier, and the charged toner on the developer carrier is exposed to the surface of the photosensitive drum 413 due to the potential difference between the surface of the photosensitive drum 413 and the developer carrier. Move to and stick to.
The details of the developing device 412 will be described later.

The drum cleaning device 415 has a drum cleaning blade or the like that is in sliding contact with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after the 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 composed of an endless belt, and is stretched in a loop on a plurality of support rollers 423. At least one of the plurality of support rollers 423 is composed of a driving roller, and the other is composed of a driven roller. For example, it is preferable that the roller 423A arranged on the downstream side in the belt traveling direction with respect to the primary transfer roller 422 for the K component is the drive roller. This makes it easier to keep the running speed of the belt in the primary transfer unit constant. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. By pressing the primary transfer roller 422 against the photosensitive drum 413 with the intermediate transfer belt 421 sandwiched between them, a primary transfer nip for transferring the toner image from the photosensitive drum 413 to the intermediate transfer belt 421 is formed.

The secondary transfer roller 424 is arranged on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B arranged on the downstream side of the drive roller 423A in the belt traveling direction. By pressing the secondary transfer roller 424 against the backup roller 423B with the intermediate transfer belt 421 sandwiched between them, a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S is formed.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photosensitive drum 413 is sequentially superimposed on the intermediate transfer belt 421 and the primary transfer is performed. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and a charge opposite to that of the toner is applied to the back surface side (the side that abuts the primary transfer roller 422) of the intermediate transfer belt 421 to obtain a toner image. It is electrostatically transferred to the intermediate transfer belt 421.

After that, when the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the paper S. Specifically, a toner image is obtained 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 on the back surface side of the paper S (the side that comes into contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The paper S on which the toner image is transferred is conveyed toward the fixing portion 60.

The belt cleaning device 426 has a belt cleaning blade or the like that is in sliding contact with the surface of the intermediate transfer belt 421, and removes the transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

In the intermediate transfer unit 42, instead of the secondary transfer roller 424, a secondary transfer belt is stretched in a loop on a plurality of support rollers including the secondary transfer roller (so-called belt-type secondary transfer). A unit) may be adopted.

The fixing portion 60 is on the upper fixing portion 60A having a fixing surface side member arranged on the fixing surface (the surface on which the toner image is formed) side of the paper S, and on the back surface (opposite surface of the fixing surface) side of the paper S. It includes a lower fixing portion 60B having a back surface side support member to be arranged, a heating source 60C, and the like.

When the upper fixing portion 60A is a belt heating method (see FIG. 1), the fixing belt is a fixing surface side member, and when the roller heating method is used, the fixing roller is a fixing surface side member. When the lower fixing portion 60B is of the roller pressurizing method (see FIG. 1), the pressurizing roller is the back surface side support member, and when the belt pressurization method is used, the pressurizing belt is the back surface side support member. By pressing the back surface side support member against the fixing surface side member, a fixing nip that narrowly holds and conveys the paper S is formed.

The fixing unit 60 fixes the toner image on the paper S by secondarily transferring the toner image and heating and pressurizing the conveyed paper S with the fixing nip. The fixing unit 60 is arranged as a unit in the fixing device F. Further, the fuser F may be provided with an air separation unit that separates the paper 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 first transport unit 53, a second transport unit 54, and the like.
Paper S (standard paper, special paper) identified based on the basis weight, size, etc. is stored in the three paper feed tray units 511 to 513 constituting the paper feed unit 51 for each preset type. ..

The first transport section 53 includes a plurality of transport roller sections including an intermediate transport roller section 531, a loop roller section 532, and a resist roller section 533. The first transport unit 53 transports the paper S fed from the paper feed unit 51 or an external paper feed device (not shown) to the image forming unit 40 (secondary transfer unit).

The second transport section 54 includes a switchback path 541 in which a plurality of transport roller sections are arranged and a back surface transport path 542. The second transport unit 54 reverses the paper S by once transporting the paper S to the switchback path 541, then switching back and transporting the paper S to the back surface transport path 542, and the first transport unit 53 (loop roller). It is supplied to the upstream of the unit 532).

The paper S fed from the paper feeding unit 51 or the external paper feeding device (not shown) is conveyed to the image forming unit 40 by the first conveying unit 53. Then, when the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is collectively secondarily transferred to one surface (surface) of the paper S, and the fixing process is performed on the fixing portion 60. Toner. The paper S on which the image is formed is discharged to the outside of the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

FIG. 2 is a plan view schematically showing an example of the developing apparatus 412 according to the embodiment. FIG. 3 is a cross-sectional view taken along the line AA of the developing apparatus 412 shown in FIG. FIG. 4 is a partially enlarged cross-sectional view of FIG. FIG. 5 is a sectional view taken along line BB of the developing apparatus 412 shown in FIG. In FIG. 2, the left-right direction is referred to as "axial direction", "one direction", or "long axis direction". Further, in FIG. 2, the vertical direction is referred to as a "minor axis direction". In FIG. 3, the developing roller 84 is omitted.

As shown in FIG. 2, the developing device 412 includes a developing device main body 80, a toner supply unit that supplies toner to the developing device main body 80 (not shown), and a carrier supply unit that supplies carriers to the developing device main body 80 (not shown). ) Is provided.

The developing apparatus main body 80 includes a developer accommodating unit 81, a stirring screw 82, a supply screw 83, a developing roller 84 (corresponding to the “developer carrier” of the present invention), a developer bulk detection unit 85, and a toner concentration detection unit. 86 is provided.

The developer accommodating unit 81 accommodates a two-component developer composed of toner and a carrier. The developer accommodating unit 81 has a circulation path 810 in which the developer circulates. The circulation path 810 includes a developer stirring path 811 and a developer supply path 812 extending parallel to the axial direction of the developing roller 84, a folded-back portion 813 connecting the paths 811 and 812 to each other at the left end in the axial direction, and a path 811. , 812 have a folded-back portion 814 that connects the 812 to each other at the right end in the axial direction.

As shown in FIGS. 2, 3 and 5, the developer stirring path 811 and the developer supply path 812 are partitioned by the partition wall 87. The developer agitation path 811 is farther from the developing roller 84 than the developer supply path 812. The developer transport direction in the developer stirring path 811 and the developer transport direction in the developer supply path 812 are opposite to each other. In the present embodiment, the axial lengths of the developer stirring path 811 and the developer supply path 812 correspond to the axial lengths of the partition wall 87.

As shown in FIGS. 2 and 5, the folded-back portion 813 has an opening 88 arranged at the left end in the axial direction of the partition wall 87. The folded-back portion 813 communicates the developer stirring path 811 and the developer supply path 812 with each other via the opening 88 at the left end in the axial direction. In the present embodiment, the axial length of the folded-back portion 813 corresponds to the axial width of the opening 88.

As shown in FIGS. 2 and 5, the folded-back portion 814 has an opening 89 arranged at the right end in the axial direction of the partition wall 87. The folded-back portion 814 communicates the developer stirring path 811 and the developer supply path 812 with each other via the opening 89 at the right end in the axial direction. The folded-back portion 814 communicates with a discharge path for discharging a part of the developer (the arrow indicates the discharge direction of the developer in FIG. 2). In the present embodiment, the axial length of the folded-back portion 814 corresponds to the axial width of the opening 89.

As shown in FIG. 2, a stirring screw 82 is arranged along the axial direction in the developer stirring path 811. The stirring screw 82 has a configuration in which blades 822 are spirally formed at a predetermined pitch over substantially the entire length of the shaft center 821 connected to a drive motor (not shown). The blade 822a arranged in the vicinity of the opening 88 from the developer stirring path 811 toward the developer supply path 812 spirals in the opposite direction to the blade 822 in order to circulate the developer in the developer supply path 812. It is formed in a shape. By rotating the stirring screw 82, the toner and the carrier are conveyed in the axial direction (from right to left in FIG. 2) while being agitated.

As shown in FIG. 2, a supply screw 83 is arranged along the axial direction in the developer supply path 812. The supply screw 83 has a configuration similar to that of the stirring screw 82, that is, the blades 832 are spirally formed at a predetermined pitch over almost the entire length of the shaft center 831 connected to the drive motor (not shown). .. The blade 832a arranged in the vicinity of the opening 89 from the developer supply path 812 toward the developer stirring path 811 spirals in the direction opposite to that of the blade 832 in order to circulate the developer in the developer stirring path 811. It is formed in a shape. By rotating the supply screw 83, the toner and the carrier are conveyed in the axial direction (from left to right in FIG. 2) while being agitated.

When the developer is conveyed in the developer stirring path 811 and the developer supply path 812, the toner contained in the developer and the carrier are in frictional contact with each other and are charged to opposite polarities. Here, the carrier is charged positively and the toner is charged negatively. The negatively charged toner adheres to the periphery of the positively charged carrier mainly by the electric suction force of both. Then, the developer is supplied to the developing roller 84 in the process of being conveyed through the developer supply path 812.

The developing roller 84 is, for example, a so-called magnet roller having a magnet body fixed so as not to rotate (not shown) and a cylindrical transport sleeve (not shown) rotatably arranged around the magnet body. The developing roller 84 supplies the developing agent to the photosensitive drum 413 on which the electrostatic latent image is formed. By supplying the toner carried on the transport sleeve to the photosensitive drum 413, the electrostatic latent image on the photosensitive drum 413 is developed.

The developer accommodating portion 81 is integrally composed of a metal portion and a non-metal portion. Here, the metal portion is formed of a metal material having high thermal conductivity, for example, aluminum. Further, the non-metal portion is formed of, for example, a resin material.

As shown in FIG. 2, the circulation path 810 of the developer accommodating portion 81 has a developer stirring path 811 and a developer supply path 812 partitioned by a partition wall 87, and a folded-back portion 815,814. In the developer stirring path 811, the right direction in FIG. 2 is referred to as "upstream side in the developer transport direction", and the left direction is referred to as "downstream side in the developer transport direction". Further, in the developer supply path 812, the left direction in FIG. 2 is referred to as "upstream side in the developer transport direction", and the right direction is referred to as "downstream side in the developer transport direction".

As shown in FIG. 2, the axial central portion PC of the circulation path 810 is composed of a metal portion. Further, the central portion PC in the axial direction faces the developing roller 84 in a direction orthogonal to the axial direction. The left end PL of the circulation path 810 in the axial direction is composed of a non-metal portion. The axial right end PR of the circulation path 810 is composed of a non-metal portion.

The developer stirring path 811 and the developer supply path 812 include a part of the axial central portion PC and a part of the axial right end portion PR. Therefore, the developer stirring path 811 and the developer supply path 812 are composed of a metal portion and a non-metal portion.

The folded-back portion 813 includes a part of the axial left end portion PL and the axial central portion PC. Therefore, the folded-back portion 813 is composed of a metal portion and a non-metal portion.

The folded-back portion 814 is included in the right end portion PR in the axial direction. Therefore, the folded-back portion 814 is composed of a non-metal portion.

As shown in FIGS. 2 to 4, the wall portion 817 of the axially central portion PC composed of the metal portion has a through hole HL penetrating in the inside / outside direction (vertical direction in FIG. 2) of the developer accommodating portion 81. ing. The non-metal portion 90 (resin member) is arranged so as to close the through hole HL from the outside of the developer accommodating portion 81.

The developer bulk detection unit 85 is attached to the wall portion 817 of the axially central portion PC via the non-metal portion 90. The developer bulk detection unit 85 is arranged at a position distant from the opening 88 on the upstream side in the developer transport direction. A known sensor for detecting the bulk (liquid level) of the developer in the developer accommodating unit 81 is used in the developer bulk detection unit 85. The developer bulk detection unit 85 is, for example, a magnetic permeability sensor that detects the magnetic permeability of the developer. The developer bulk detection unit 85 detects the volume of the developer in the developer housing 81, for example, with reference to a table showing the relationship between the distance between the sensor surface and the object to be detected and the detected value.

A sensor unit is arranged at the right end of the developer bulk detection unit 85. A connector portion is arranged at the left end portion of the developer bulk detection portion 85. That is, the connector portion is arranged on the downstream side in the developer transport direction. The sensor unit is arranged on the upstream side in the developer transport direction.

As shown in FIGS. 2 and 3, the toner concentration detecting unit 86 is arranged at the bottom portion 818 of the folded-back portion 813 via the non-metal portion 90. The toner concentration detection unit 86 detects the toner concentration. A known sensor is used for the toner concentration detection unit 86. The toner concentration detection unit 86 is, for example, a magnetic permeability sensor that detects the magnetic permeability of the developer. The toner concentration detection unit 86 detects the toner concentration by referring to, for example, a table showing the relationship between the toner concentration and the detected value.

The toner concentration detection unit 86 is arranged on the downstream side in the developer transport direction with respect to the developer bulk detection unit 85. In other words, the developer bulk detection unit 85 is arranged on the upstream side in the developer transport direction with respect to the toner concentration detection unit 86.

The developing device 412 in the above embodiment is a developing device that visualizes the electrostatic latent image and forms the toner image by adhering the toner to the electrostatic latent image formed on the surface of the image carrier. A developer accommodating portion 81 having a formed metal portion and a non-metal portion composed of non-metal and accommodating a developer containing toner, and a developer accommodating portion 81 arranged in the non-metal portion and in the developing agent accommodating portion 81. A developer bulk detection unit 85 for detecting the bulk of the developer is provided.

According to the above configuration, as compared with the case where the developer bulk detection unit 85 is arranged on the metal portion, the adverse effect of detecting the bulk of the developer is small, so that the detection accuracy of the bulk of the developer is improved. It becomes possible.

Further, in the above embodiment, the developer accommodating portion 81 has a through hole HL penetrating in the inward and outward directions of the developer accommodating portion 81, and the developer bulk detection unit 85 is a non-metal that closes the through hole HL. It is arranged in the part 90. As a result, since the developer accommodating portion 81 can be composed of a metal portion having high thermal conductivity, the heat generated by the frictional contact between the toner and the carrier is transferred to the outside through the developer accommodating portion 81. This makes it possible to prevent the temperature of the developing apparatus 412 from rising.

Further, in the above embodiment, the circulation path 810 is integrally composed of a metal portion and a non-metal portion 90. As a result, it is possible to improve the accuracy of detecting the bulk of the developer and to prevent the temperature of the developing apparatus 412 from rising.

Further, in the above embodiment, the central portion of the circulation path 810 in the axial direction is composed of a metal portion. Thereby, the temperature rise in the circulation path 810 can be prevented. Further, the axial end portion of the circulation path 810 is composed of at least a non-metal portion. This makes it possible to arrange the developer bulk detection unit 85 on the non-metal portion.

Further, in the above embodiment, the folded-back portion 814 communicates with a discharge path for discharging a part of the developer and is composed of a non-metal portion. As a result, the non-metal portion 90 can be extended to the discharge path relatively easily. Further, the developer bulk detection unit 85 can be arranged on the non-metal portion.

Further, in the above embodiment, the region facing the developing roller 84 in the developer supply path 812 (here, simply referred to as “region”) is composed of a metal portion. Specifically, the region is composed of, for example, an extruded aluminum material. On the other hand, when the region is made of resin, for example, the resin may be warped and it may be difficult to obtain the processing accuracy of the region. In the present embodiment, since the region is composed of an extruded aluminum material or the like, the processing accuracy of the region is easy to obtain as compared with the case of resin, and the gap between the region and the developing roller 84 is likely to be uniform. There is an advantage. This makes it possible to evenly convey the developer to the surface of the developing roller 84.

Further, in the above embodiment, the developer bulk detection unit 85 is arranged at a position separated from the opening 88 in the transport direction of the developer. In the opening 88, since the bulk (liquid level) of the developer is not stable in the region where the developer is fed by the stirring screw 82, the detection accuracy of the bulk of the developer is lowered. In the present embodiment, since the developer bulk detection unit 85 is arranged at a position away from the opening 88 on the upstream side, the bulk of the developer is stable and the detection accuracy of the bulk of the developer can be improved. ..

Further, in the above embodiment, the developer bulk detection unit 85 is arranged on the upstream side of the toner concentration detection unit 86 in the transport direction of the developer. In other words, the toner concentration detection unit 86 is arranged on the downstream side (closer to the opening 88) in the transport direction than the developer bulk detection unit 85. The region on the downstream side in the transport direction is a region where the developer tends to stay, but since the region has little fluctuation in the bulk of the developer, it can be used as a region for detecting the toner concentration.

Further, in the above embodiment, the sensor unit is arranged on the upstream side in the transport direction of the developer. The sensor unit outputs a detection signal according to the bulk of the developer. The connector portion is arranged on the downstream side in the transport direction of the developer. The connector portion is for transmitting a detection signal. This makes it possible to further improve the accuracy of detecting the bulk of the developer. Further, for example, since the length of the wiring extending from the connector to the downstream side in the transport direction is shortened, it is not necessary to take a large space for installing the developer bulk detection unit 85, and the efficiency of the installation space can be improved. Can be done.

Next, a modified example will be described with reference to FIG. FIG. 6 is a plan view schematically showing the developing apparatus according to the modified example. FIG. 7 is a sectional view taken along line CC of the developing apparatus 412 shown in FIG. In FIG. 6, a part of the blade 822 of the stirring screw 82 is shown by a broken line in order to make the shape of the non-metal portion 91 easy to understand. Further, in FIG. 7, the developing roller 84 is omitted. Further, in FIG. 7, the non-metal portion 91 is shown by hatching. In the modified example, a configuration different from that of the above embodiment will be mainly described, and the same configuration will be designated by the same reference numerals and the description thereof will be omitted.

In the modified example, the non-metal portion 91 extends from the folded portion 813 toward the developer stirring path 811. The non-metal portion 91 is arranged in place of a part of the metal portion constituting the developer stirring path 811. The developer bulk detection unit 85 is arranged in the non-metal portion 91 arranged in place of a part of the metal portion. As a result, it is not necessary to provide the through hole HL in the developer accommodating portion 81, and it is not necessary to close the through hole HL with the non-metal portion 90. Further, the developer bulk detection unit 85 can be arranged on the upstream side farther from the opening 88. As a result, the accuracy of detecting the bulk of the developer can be further improved.

Further, as can be seen by comparing the cross-sectional shape of the developer stirring path 811 shown in FIG. 3 with the cross-sectional shape of the developer stirring path 811 shown in FIG. 7, in the modified example, the non-metal portion 91 is a metal portion. The cross-sectional shape of the developer stirring path 811 at the position where it is arranged in place of a part is the same as the cross-sectional shape of the developer stirring path 811 at the position where the non-metal part 91 is not placed in place of a part of the metal part. is there. As a result, it is not necessary to widen the width of the developer stirring path 811 in the minor axis direction, and it is possible to prevent the developing device 412 from becoming large.

In the above-described embodiment and modification, the place where the developer bulk detection unit 85 is arranged is a non-metal portion in the developer stirring path 811, but the present invention is not limited to this, and the change in the bulk of the developer is not limited to this. It suffices if it is a region with a small amount of water and is a non-metal part.

In addition, the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

The present invention can be applied to an image forming system composed of a plurality of units including the image forming apparatus 1. The plurality of units include, for example, an external device such as a post-processing device and a network-connected control device.

PC Axial center PL Axial left end PR Axial right end 1 Image forming device 80 Developer body 81 Developer container 82 Stirring screw 83 Supply screw 84 Developer roller 85 Developer bulk detector 86 Toner concentration detector 87 Partition 88, 89 Opening 90 Non-metal part 91 Non-metal part 100 Control unit 412 Developing device 810 Circulation route 811 Developer stirring route 812 Developer supply route 813, 814 Folded part

Claims (15)

In a developing device that visualizes an electrostatic latent image and forms a toner image by adhering toner to an electrostatic latent image formed on the surface of the image carrier.
A developer accommodating portion having a metal portion made of metal and a non-metal portion made of non-metal and accommodating a developer containing the toner, and a developer accommodating portion.
A developer bulk detection unit, which is arranged in the non-metal portion and detects the bulk of the developer in the developer accommodating portion,
To prepare
Developing equipment. The developer bulk detection unit is a magnetic permeability sensor that detects the magnetic permeability of the developer.
The developing apparatus according to claim 1. The developer accommodating portion has a through hole penetrating in and out of the developer accommodating portion.
The developer bulk detecting portion is arranged in the non-metal portion that closes the through hole.
The developing apparatus according to claim 1 or 2. The developer accommodating portion has a circulation path through which the developer circulates.
The circulation path is integrally composed of the metal portion and the non-metal portion.
The developing apparatus according to any one of claims 1 to 3. In the circulation path, the developer stirring path and the developing agent supply path extending in parallel in a predetermined direction and the developer stirring path and the developing agent supply path are connected to each other at both ends in one direction so that the developer is circulated and conveyed. Has two folds and
The central portion of the circulation path in the predetermined direction is composed of the metal portion.
The end of the circulation path in the predetermined direction is composed of at least the non-metal portion.
The developing apparatus according to claim 4. One of the two folded portions communicates with a discharge path for discharging a part of the developer and is composed of the non-metal portion.
The developing apparatus according to claim 5. The other of the two folded portions is composed of the metal portion and the non-metal portion.
The developing apparatus according to claim 5 or 6. The region of the developer accommodating portion facing the developer carrier is composed of the metal portion.
The developing apparatus according to any one of claims 5 to 7. The circulation path has a partition wall that separates the developer stirring path and the developer supply path.
The folded portion is arranged at both ends in one direction of the partition wall, and has an opening in which the developer stirring path and the developer supply path communicate with each other.
The developer bulk detection unit is arranged at a position distant from the upstream side of the opening in the transport direction of the developer in the developer accommodating unit.
The developing apparatus according to any one of claims 5 to 8. A toner concentration detecting unit for detecting the toner concentration arranged at the bottom of the folded-back portion is further provided.
The developer bulk detection unit is arranged on the upstream side of the toner concentration detection unit in the transport direction of the developer in the developer storage unit.
The developing apparatus according to any one of claims 5 to 9. The developer bulk detection unit includes a sensor unit that outputs a detection signal according to the bulk of the developer and a connector unit for transmitting the detection signal.
The sensor unit is arranged on the upstream side of the developer accommodating unit in the transport direction of the developer.
The connector portion is arranged on the downstream side of the developer accommodating portion in the transport direction of the developer.
The developing apparatus according to any one of claims 5 to 10. The non-metal portion extends from the folded portion toward the developer stirring path and is arranged in place of a part of the metal portion constituting the developer stirring path.
The developing apparatus according to any one of claims 5 to 11. The developer bulk detecting portion is arranged in the non-metal portion arranged in place of a part of the metal portion.
The developing apparatus according to claim 12. The cross-sectional shape of the developer transport path at a position where the non-metal portion is arranged in place of a part of the metal portion is such that the developer is in a position where the non-metal portion is not arranged in place of a part of the metal portion. Same as the cross-sectional shape of the stirring path,
The developing apparatus according to claim 12 or 13. An image forming apparatus comprising the developing apparatus according to any one of claims 1 to 14, wherein a toner image is formed on an image carrier by the developing apparatus.

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