JP2002148921A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such as splashes of toner and development fogging by securing stable image density at all times irrespective of a print rate and toner consumption quantity. SOLUTION: This developing device is provided with a developer carrier 41 to be opposite to an image carrier 1, a developer supplying part 401 to supply a developer to the developer carrier 41, a developer stirring part 402 to stir and supply the developer to the developer supplying part 401, a peeling means to peel the developer the developing processing of which is completed on the developer carrier 41, a developer recovery part 403 to recover the developer peeled by the peeling means and to transport it to a downstream part of a non-image formation area of the developer supplying part 401, a first toner replenishing means 51 to send replenishment toner in the vicinity of upstream of the developer transporting direction of the developer stirring part 402 and a second toner replenishing means 52 to send the replenishment toner to the upstream side of the transporting direction of the developer of the developer recovery part 403.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, and a multifunction peripheral having these functions, and more particularly, to an electrostatic latent image formed on an image carrier. The present invention relates to an improvement in a developing device for developing an image.

[0002]

2. Description of the Related Art A conventionally known image forming apparatus such as an electrophotographic copying machine performs charging and exposure on an image carrier,
An electrostatic latent image is formed. The latent image formed on the image carrier becomes a toner image by a developing device, and is transferred onto a sheet by a transfer unit. Thereafter, the image is thermally fixed by a fixing device to form an image.

A developing device develops and visualizes an electrostatic latent image formed on an image carrier using a two-component developer composed of a toner and a carrier.

The developer whose toner has been consumed after the completion of the developing process in the developing area is collected and mixed with the replenished toner.
It is agitated and subjected to development again. The developer used in the developing device having such a configuration needs to maintain a constant toner density and a constant charge amount in order to obtain a stable toner image. The toner density is determined by the distribution of the toner consumed in the development and the replenishment toner. The charge amount is determined by frictional charging when the carrier and the toner are mixed. The developing device sufficiently agitates the two-component developer composed of the toner and the carrier,
The toner density distribution is made uniform and the amount of charge applied to the toner is saturated to stabilize the toner image.

FIG. 10 is a central sectional view of a conventional developing device. The developing device 4 is disposed close to and opposed to the image carrier 1 such as a photosensitive drum, and stores a developer.
0, developer carrier 41, magnetic field generating means 42, developer regulating member 43, supply member 44, transport member 45, stirring member 4
6, the collection member 49 and the like.

In the developing device 4, the toner in the toner replenishing means 50 is supplied to the upstream side in the transport direction of the stirring member 46, and is mixed and stirred with the developer contained in the developing device main body 40. The developer mixed with the toner is agitated and transported by the transport member 45, released by the supply member 44 in a direction orthogonal to the rotation axis, and supplied onto the developer carrier 41. The developer held on the developer carrier 41 is
After the amount of the developer is regulated by the developer regulating member 43, the developer is subjected to a developing process in a developing region where the image carrier 1 and the developer carrier 41 face each other, and then peeled off by the peeling magnetic pole of the magnetic field generating means 42. The sheet is conveyed by the collection member 49 after sliding down the inclined surface, and is sent to the stirring member 46 via the conveyance member 45 below.

In this developing device 4, the supply member is disposed obliquely below the center of the developer carrier, and the collection member 49 is disposed above the center of the developer carrier 41. The height of the device is likely to increase. To reduce the size of the apparatus, the developer regulating member 43 and the supply member 4
4. Measures such as reducing the outer diameter of the conveying member 45, the stirring member 46, and the collecting member 49 are taken. However, when these rotating members are reduced in diameter, problems such as poor stirring, poor conveyance, and poor development occur.

A conventional developing device supplies a developer from below a developing roller, performs a developing process in a developing area where an image bearing member and a developing magnetic pole of the developing roller are opposed to each other, and then strips off a magnetic pole installed above the developing roller. In order to peel off the residual developer from above the developing roller,
Even if the residual developer is peeled off, the residual developer immediately adheres to the developing roller, and a problem such as a development ghost easily occurs.

As a countermeasure, there is provided a developing device in which a peeling and conveying magnetic roller is installed above a peeling magnetic pole (release pole) of a developing roller, and the magnetic roller and the developing roller are set to the same bias to improve peeling. It was disclosed (Japanese Unexamined Patent Publication No.
204283, JP-A-2-140775, etc.).

However, in order to achieve high image quality, when the amount of the developer transported on the developing roller is used in the range of about 100 mg / cm ² to about 10 to 50 mg / cm ² , the developer adheres to the developer carrying member. Since even the toner contributes to the development, together with the developer after the development, the toner adhered on the developer carrier is also
It was necessary to transfer to the magnetic roller side for stripping and conveying. That is, when toner remains on the developer carrier of the developing roller, no toner remains on the developer carrier that transports the developer consumed in the development. The amount of toner including the toner on the developer carrier is reduced as compared with the area where the toner remains on the developer carrier, causing a difference in developability and developing ghost.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and an image forming apparatus for forming a stable image by solving the following problems.

(First Problem) A toner replenishing opening of a conventional toner replenishing means is provided only on an upstream side in a developer conveying direction of a stirring and conveying member rotatably supported in a developer collecting and stirring section. I have.

The toner replenishment is controlled by calculating a printing rate from a detection result of a toner density sensor installed upstream of the toner replenishing opening in the developer transport direction or image data, and calculating a toner corresponding to the printing rate. This was done by determining the supply amount.

However, there was no problem with the toner replenishment amount of less than 30% of the printing rate, but when the toner replenishment amount increased during copying at a high printing rate, a sufficient amount of charge was started in the developer collection and stirring section. Thus, problems such as increased image density, toner scattering and development fog occurred.

A first object of the present invention is to provide a toner replenishment control according to a printing rate, always ensuring a stable image density irrespective of a toner replenishment amount, and solving problems such as toner scattering and development fog. It is the purpose.

(Second Problem) The developer peeled off from the developer carrier is completely separated between the developer collecting and stirring section and the developing area, and a collecting and conveying section provided above the developer collecting and stirring section. When the cross-sectional area of the collecting and conveying unit is reduced (for example, when the outer diameter of the collecting member is set to 20 mm or less) for the purpose of downsizing, the position of the end of the stripping plate is reduced. When there is little developer in the collecting section when the developer is in the developer rising area, there is no problem, but the amount of developer per unit time conveyed by the developer carrier is conveyed in the axial direction by the collecting member. If the amount of the developer per unit time is larger than a certain amount, the developer tends to slip through at the tip of the peeling plate, so that the developer cannot be sufficiently peeled off from the developer carrier and an image such as a development ghost Density unevenness Problem occurs. In particular, in order to achieve the downsizing of the developing device, it is not possible to make the collecting section large, and even if a certain amount of developer accumulates in the collecting section, it is necessary to remove the developer without impairing the peeling property. It is.

A second object of the present invention is to solve the problem that even if the amount of developer per unit time conveyed from the developer carrier is larger than the amount of developer per unit time conveyed in the axial direction by the recovery member, The purpose of which is to reduce the developer stagnation occurring in the developer collection and stirring section and to always obtain a stable and uniform image without affecting the peeling of the developer from the developer carrier. It is.

Further, by reducing the overall height of the developing device, in a tandem type color image forming apparatus in which a plurality of developing devices are arranged in tandem in the height direction, the size of the image forming unit can be reduced by reducing the thickness of the developing device. .

[0019]

The above first object is achieved by a developing device described in any one of the following (1) to (3).

(1) A developer carrier facing an image carrier carrying an electrostatic latent image, a developer supply unit for supplying a developer to the developer carrier, and a developer supplied to the developer supply unit A developer agitating section for agitating the developer, a peeling means for peeling off the developed developer on the developer carrier, and a developer peeled off by the peeling means for collecting and developing the developer. A developer collection unit that conveys the developer to a downstream portion of the non-image forming area of the non-image forming area; a first toner replenishing unit that supplies replenishment toner near an upstream side of the developer agitating unit in a developer conveyance direction; A second toner replenishing means for feeding replenishment toner upstream in the developer transport direction.

(2) The developer is supplied to the developer carrier facing the image carrier carrying the electrostatic latent image by the developer supply unit, and the developer is regulated to a fixed amount by the developer regulating member. Developing in the region, peeling off the developer after the developing process from the developer carrier by a peeling means, sending the developer to a developer collecting section, and providing a second developer provided upstream of the developer collecting section.
The toner is replenished by the toner replenishing means, and the toner and the developer are agitated by the collecting member in the developer collecting section and transported from the downstream to the downstream of the non-image forming section of the developer supplying section. After the toner concentration is detected by the toner concentration detecting means provided in the image forming section, the toner is conveyed from a downstream portion of the non-image forming portion of the developer supply portion to an upstream portion of the developer stirring portion, and a first portion provided near the upstream portion is provided. Supplying toner from the toner replenishing means under the control of the toner concentration detecting means, agitating the replenished toner and the developer by a stirring member in a developer agitating section, and conveying the toner to a downstream portion; A one-way developer circulation path for conveying and supplying the developer to an upstream portion of the developing device.

(3) a developer carrier facing the image carrier for carrying the electrostatic latent image, a developer supply unit for supplying a developer to the developer carrier, and a developer supplied to the developer supply unit; A developer agitating section for agitating the developer, a peeling means for peeling off the developed developer on the developer carrier, and a developer peeled off by the peeling means for collecting and developing the developer. A developer collection unit that conveys the developer to a downstream portion of the non-image forming area of the non-image forming area; a first toner replenishing unit that supplies replenishment toner near an upstream side of the developer agitating unit in a developer conveyance direction; A second toner replenishing means for supplying replenished toner to an upstream portion of the developer transport direction, and a toner concentration sensor provided downstream of the developer supply portion in the developer transport direction. Means is a detection signal from the toner concentration sensor. The toner is supplied by the second
Wherein the toner replenishing means is controlled so as to replenish the toner at least at the time of forming a high print rate image based on the print rate calculated from the image data.

The second problem is as follows (4) to (4).
This is achieved by the developing device according to any one of (7).

(4) A developer is supplied by a supply member to a developer carrier facing the image carrier that carries the electrostatic latent image;
The developer is regulated to a fixed amount by a developer regulating member, the developing process is performed in a developing region, and the developer after the developing process is peeled off from the developer carrier by a peeling means and sent to a developer collecting unit. The developer is agitated by a collection member in the developer collection unit, and is transported from a downstream portion to a downstream portion of the non-image forming area of the developer supply unit, and is transported from the downstream portion to an upstream portion of the developer agitation unit. The toner is replenished by toner replenishing means provided in the vicinity of the toner supply section, the replenished toner and the developer are agitated by a stirring member in a developer agitating section and transported to a downstream portion, and further transported to a supply member in a developer supply section. Developing device,
The recovery member satisfies the following condition.

Vs × L × D1 <π × (A ² −B ² ) × p ×
R × K × α / 400 α = D2 / (π × (A ² −B ² ) × p × R × K) × 400 where Vs is the rotational peripheral speed of the developer carrier [cm / sec] L is A developer transport width [cm] in the axial direction of the developer carrier D1 is a developer transport amount per unit area [g / cm] regulated by the developer regulating member and transported onto the developer carrier.
² ] D2 is the amount of developer falling per unit time [g / sec] from the downstream opening of the developer collecting unit when the developer is stored in the developer collecting unit and the collecting member is rotated at a predetermined rotation speed. Is the outer diameter of the collecting member [cm] B is the outer diameter of the rotating shaft of the collecting member [cm] p is the screw pitch of the collecting member [cm] R is the number of rotations per second of the collecting member [rps] K is the bulk of the developer Density [g / cm ³ ] α is developer transport rate [%] (5) The developer is supplied to the developer carrier facing the image carrier carrying the electrostatic latent image by the supply member, and the developer regulating member is provided. The developer is regulated to a constant amount by a developing process, and the developing process is performed in a developing area. The developer after the developing process is peeled off from the developer carrier by a peeling means and sent to a developer collecting section. The developer is agitated by the collecting member, and the developer supply portion is Transported to the downstream portion of the non-image forming area, and transported from the downstream portion to the upstream portion of the developer stirring section,
The toner is replenished by toner replenishing means provided in the vicinity of the upstream portion, the replenished toner and the developer are agitated by a stirring member in a developer agitating portion and conveyed to a downstream portion. A developing device that conveys to an upstream portion of a member, wherein a developer protrudes from an upper lid that closes an upper portion of the developer collection unit between the stripping unit and the collection member in the vicinity of the collection member. A developing device provided with a backflow preventing member, wherein the developer collected by the collecting member is regulated by the developer backflow preventing member so as not to flow back to the stripping means.

(6) A developer is supplied from a supply member to a developer carrier facing the image carrier carrying the electrostatic latent image, and
The developer is regulated to a fixed amount by a developer regulating member, the developing process is performed in a developing region, and the developer after the developing process is peeled off from the developer carrier by a peeling means and sent to a developer collecting unit. The developer is agitated by a collection member in the developer collection unit and transported from a downstream portion to a downstream portion of the non-image forming region of the developer supply portion, and is transported from the downstream portion to an upstream portion of the developer agitation portion. The toner is replenished by toner replenishing means provided in the vicinity of the upstream portion, the replenished toner and the developer are agitated by a stirring member in the developer stirring portion and transported to the downstream portion. A developing device for transporting the developer to an upstream portion, wherein the stripping unit includes: a developer stripping magnetic pole that releases a residual developer on the developer carrier; and a developer stripping magnetic pole of the developer carrier. Installed in close proximity to a fixed A peeling roller that carries the developer on a rotatable rotating member, peels the developer from the developer carrier, and transports the developer to the collection member; and a peeling roller. And a stripping plate provided in the developer collecting portion in proximity to the developer stripping magnetic pole, and the gap between the tip of the stripping plate and the outer peripheral surface of the stripping roller is 0.4 mm or less. At the position where the tip of the peeling plate is not in contact with the developer rising at the developer peeling magnetic pole of the peeling roller, the developer rising at the developer peeling magnetic pole Wherein the angle is set within a range of 30 ° in the rotation direction from the most downstream position in the rotation direction.

(7) A developer is supplied from a supply member to a developer carrier facing the image carrier that carries the electrostatic latent image, and
The developer is regulated to a fixed amount by a developer regulating member, the developing process is performed in the developing region, and the developer after the developing process is peeled off from the developer carrier by a peeling means and sent to a developer collecting unit. The developer is agitated by the recovery member in the developer recovery unit and transported from the downstream to the downstream of the non-image forming area of the developer supply unit, and transported from the downstream to the upstream of the developer agitator, The toner is replenished by toner replenishing means provided in the vicinity of the upstream portion, and the replenished toner and the developer are stirred by a stirring member in a developer stirring portion and transported to the downstream portion,
Further, the developing device transports the developer to an upstream portion of the supply member in the developer supply unit, wherein the stripping unit includes a developer stripping magnetic pole that discharges a residual developer on the developer carrier, and A peeling plate provided in the developer collecting portion in proximity to the developer peeling magnetic pole, and a gap between a distal end portion of the peeling plate and an outer peripheral surface of the developer carrier,
0.4 mm or less, and, at the position where the tip of the stripping plate does not come into contact with the developer that stands at the developer stripping magnetic pole of the developer carrier, the developer stripping magnetic pole A developing device, wherein the angle is set within a range of 30 ° in the rotational direction from the most downstream position in the rotational direction of the rising developer.

The first and second problems are described in the following (8) and (9) provided with the developing device according to any one of the above (1) to (7). This is achieved by an image forming apparatus.

(8) A charging device and an exposure device for forming an electrostatic latent image on the image carrier, the developing device according to any one of (1) to (7), and a developing device formed by the developing device Transfer means for transferring the transferred toner image onto recording paper, paper feeding means for feeding recording paper to the transfer means, and fixing means for fixing a transferred image formed on the recording paper. Image forming device.

(9) A charging device for forming an electrostatic latent image on an image bearing member, a plurality of exposing devices, and any one of (1) to (7), each containing a developer of a different color. A developing device, a transfer unit that transfers a toner image formed by the developing device to recording paper, a paper feeding unit that feeds the recording paper to the transfer unit, and a transfer image formed on the recording paper. An image forming apparatus, wherein a plurality of color toner images are formed on the recording paper by a fixing unit for fixing.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiment of the developing device of the present invention, the structure of a color copying machine as an example of an image forming apparatus equipped with a plurality of developing devices of the present invention will be described.

(Configuration of Image Forming Apparatus) FIG. 1 is an overall configuration diagram of a color copying machine including an image forming apparatus main body 100 and an image reading apparatus 200.

The image forming apparatus main body 100 is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer body 6, a sheet feeding and conveying means, And a fixing device 24.

Image forming section 1 for forming a yellow image
0Y is a charging unit 2Y disposed around the photoreceptor 1Y,
It has an exposure unit 3Y, a developing device 4Y, and a cleaning unit 8Y. Image forming unit 10M that forms a magenta image
Has a photoreceptor 1M, a charging unit 2M, an exposing unit 3M, a developing unit 4M, and a cleaning unit 8M. The image forming section 10C for forming a cyan image has a photoreceptor 1C, a charging unit 2C, an exposing unit 3C, a developing device 4C, and a cleaning unit 8C. Image forming unit 10K for forming a black image
Has a photoreceptor 1K, a charging unit 2K, an exposing unit 3K, a developing unit 4K, and a cleaning unit 8K.

The intermediate transfer member 6 is wound around a plurality of rollers and is rotatably supported. Image forming unit 10Y,
Images of each color formed from 10M, 10C, and 10K are:
Transfer means 7Y, 7M, 7C, on the rotating intermediate transfer body 6,
The images are sequentially transferred by 7K (primary transfer), and a combined color image is formed. The sheet P stored in the sheet cassette 20 is fed by a sheet feeding unit 21, is conveyed to a transfer unit 7 A via sheet feeding rollers 22 A, 22 B, 22 C, registration rollers 23, and the like, and is transferred onto the sheet P in color. The image is transferred (secondary transfer). The paper P to which the color image has been transferred is subjected to a fixing process by the fixing device 24 and the paper discharging roller 2
5 and is placed on a discharge tray 26 outside the apparatus.

On the other hand, after the color image is transferred onto the sheet P by the transfer means 7A, the intermediate transfer member 6 obtained by separating the sheet P by curvature is used.
The remaining toner is removed by the cleaning means 8A.

5Y, 5M, 5C and 5K are the developing devices 4
A toner replenishing unit that replenishes new toner to Y, 4M, 4C, and 4K.

An image reading device 200 including an automatic document feeder 201 and a document image scanning and exposing device 202 is provided above the image forming apparatus main body 100. The document d placed on the document table of the automatic document feeder 201 is conveyed by a conveying means, and one side or both sides of the document is scanned and exposed by the optical system of the document image scanning and exposing device 202, and is sent to the line image sensor CCD. Is read.

The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing section 1 and then to an image writing section (exposure means) 3Y. ,
Send signals to 3M, 3C, 3K.

Image Forming Apparatus Main Body 1 in the Present Embodiment
In the case of 00, the automatic document feeder 201 includes an automatic double-sided document conveying means. Since the automatic document feeder 201 can continuously read the contents of a large number of documents d fed from the document mounting table at once and accumulate them in the storage means (electronic RDH function), the copying operation can be performed. It is conveniently used when copying the contents of a large number of documents by the function, or when transmitting a large number of documents d by the facsimile function.

The image reading device 200 reads a document image, calculates a printing rate, and integrates the printing rate. (Structure of Developing Device) FIG. 2 is a central sectional view of the developing device according to the present invention, and FIG. 3 is a schematic diagram showing circulation of the developer in the developing device. Hereinafter, the developing devices 4Y, 4M, 4C, and 4K will be referred to as a developing device 4 as a representative.

The developing device 4 includes a developing device main body 40, a developer carrier (developing sleeve) 41, a magnetic field generating means (magnet roll) 42, a developer regulating member (spike plate) 43, and a supply member (paddle wheel) 44. , Conveying member (conveying screw) 45, stirring member (stirring screw) 46, stripping roller 47, stripping plate 48, collecting member (collecting screw) 49, toner concentration sensor (toner concentration detecting means)
It is composed of TS and the like.

The developer carrier 41 is arranged to face the image carrier 1 carrying an electrostatic latent image, and is rotatably supported.

The magnetic field generating means 42 is disposed inside the developer carrier 41 and has a plurality of magnetic poles N1, N2, S1, S2,
S3. Two magnetic poles S2 and S3 adjacent to each other among the plurality of magnetic poles of the magnetic field generating means 42 are arranged with the same polarity to form a repulsive magnetic field. Magnetic pole S2 for removing developer
Removes and scatters the developer on the developer carrier 41. The developer receiving magnetic pole S <b> 3 sucks the developer supplied by the supply member 44 and causes the developer to adhere to the developer carrier 41.

The supply member 44 is a rotatable paddle for supplying the developer to the developer carrier 41, and brings the developer conveyed from the carrier member 45 near the developer receiving magnetic pole S 3 of the developer carrier 41. Supply evenly.

The transport member 45 is arranged in parallel with the supply member 44, and agitates the developer transported from the stirring member 46 and transports the developer to the supply member 44.

The stirring member 46 mixes the supplied new toner and the developer recirculated from the conveying member 45, stirs the mixed toner, and conveys the mixed toner to an upstream portion of the conveying member 45.

In the vicinity of the developer stripping magnetic pole S2 of the developer carrier 41, a stripping roller 47 is disposed. The peeling roller 47 includes a rotatable rotating member (sleeve) 47A and a columnar magnet body 47B housed inside the rotating member 47A and fixed to the developing device main body 40. The magnet body 47B is, for example, n1, n2, s1, s
The magnetic pole n1 is composed of five magnetic poles 2, 2 and s3.
The two magnetic poles s2 and s3 adjacent to and adjacent to the first developer stripping magnetic pole S2 form a repulsive magnetic field of the same polarity.

In the vicinity of the magnetic pole s2, the tip of the stripping plate 48 is in close or light contact. The stripping plate 48 and the stripping roller 47 form stripping means. The developer released from the surface of the developer carrier 41 by the developer peeling magnetic pole S2 of the developer carrier 41 is sucked by the magnetic pole n1 in the peeling roller 47, and is carried and transported by the rotating rotating member 47A. In the vicinity of the magnetic pole s2, the developer is stripped off by the stripping plate 48, and the developer collecting section 403 is formed.
Fall into.

The collecting member 49 rotatably arranged in the developer collecting section 403 receives and collects the developer which is peeled off by the stripping roller 47 and the stripping plate 48 and collects the same. And is transported outside the developing area of the developer carrier 41 on the downstream side in the transport direction. If the developer does not return to the developer carrying member 41, the collected developer may be supplied to the downstream side of the carrying member 45 in the carrying direction and into the developing area of the developer carrying member 41. . Alternatively, the developer collected by the collection member 49 is
It may be refluxed to the upstream part of No. 2.

The conveying member 45, the stirring member 46, and the collecting member 4
Numeral 9 denotes a spiral screw-shaped member which conveys the developer in the direction of the rotation axis and discharges the developer in a direction substantially perpendicular to the rotation axis.

The developing device main body 40 closes an upper opening of the lower main body 40A supporting the supply member 44, the conveying member 45, and the stirring member 46, a middle main body 40B supporting the recovery member 49, and the middle main body 40B. And an upper lid 40C.

The lower body 40A includes a developer supply section 401 for accommodating the supply member 44 and the transport member 45, and a stirring member 46.
And a developer stirring section 402 that accommodates the developer. The developer supply unit 401 and the developer stirring unit 402 are formed on both sides of the first partition 404 that stands upright from the bottom of the lower main body 40A.

A second partition 405 formed at the bottom of the middle body 40B rotatably supporting the recovery member 49 partitions the developer supply section 401 and the developer recovery section 403. A part of the middle main body 40B closes an upper opening of the developer stirring section 402.

The downstream side of the developer transport of the developer recovery section 403 and the downstream side of the developer transport of the developer supply section 401 are the second section.
The partition 405 communicates with a first opening 406 formed near the end.

A second opening 407 formed in the vicinity of one end of the first partition 404 is defined between the downstream side of the developer supply section 401 and the upstream side of the developer stirring section 402.
Is communicated with.

A third opening 408 formed in the vicinity of the other end of the first partition 404 is defined between the downstream side of the developer agitating section 402 and the upstream side of the developer supply section 401.
Is communicated with.

A toner concentration sensor TS provided at the bottom of the developer supply section 401 on the downstream side of the developer transport detects the toner density of the transported developer. In response to the toner density detection signal, the control unit 9 (not shown) causes the first toner replenishing unit 5
1 to drive the toner supply opening 409 provided near the upstream side of the developer agitating section 402 for transporting the developer.
Replenish. The first toner replenishing means 51 can optically detect the image density after the development processing, and can perform toner replenishment control in accordance with the detection result of the image density.

A toner supply opening 410 is provided on the upstream side of the collection member 49 in the developer collection section 403 in the developer conveyance direction, and new toner is supplied from the second toner supply means 52. The second toner replenishing means 52 is controlled for toner replenishment in accordance with image printing rate data described later.

The developer peeled off by the peeling roller 47 and the peeling plate 48 is recovered in the developer recovery section 403, and the recovered developer is transported by the recovery member 49 to the downstream side of the developer transport. The developer is returned into the developer supply unit 401 from the first opening 406 formed in the partition 405.

The developer in the developer supply section 401 is transported by the transport member 45 into the developer agitating section 402 from the second opening 407 formed at one end of the first partition 404. The developer transported into the developer agitating section 402 is transported by the agitating member 46 while mixing and agitating the toner and the developer supplied from the toner replenishing opening 409, and the other of the first partition 404. Third opening 40 drilled at the end
8 and is returned into the developer supply unit 401.
In the developer supply unit 401, the developer is transported in the axial direction by the transport member 45 and is discharged and supplied to the supply member 44. The supply member 44 radiates the developer while conveying it in the axial direction, and supplies the developer to the developer carrier 41.

The developer recovery section 403 and the developer supply section 401
The first partition provided near the end of the second partition 405 that separates
The opening 406 and the second opening 407 and the third opening 408 provided near both ends of the first partition 404 that separates the developer supply unit 401 and the developer stirring unit 402 are all provided with a developer carrier. It is preferable to be arranged in 41 non-image forming areas.

By increasing the rotation direction of the supply member 44 and the conveying member 45 so as to be the same as the rotation direction of the developer carrier 41, the efficiency of the developer supply to the developer carrier 41 is improved. In addition to this, stable developer supply becomes possible, and a good image can be obtained.

Further, by setting the rotation direction of the recovery member 49 to be opposite to the rotation direction of the developer carrier 41, it is possible to reduce the backflow of the developer in the developer recovery section 403. . Further, the developer conveying force of the supply member 44 is set to be smaller than the developer conveying force of the conveying member 45. As a result, it is possible to prevent developer packing from occurring on the downstream side of the supply member 44 in the developer transport direction, and to perform stable developer supply to the developer carrier 41 without impairing the durability of the developer. Becomes possible.

The developer contains a magnetic carrier having a magnetization of 20 to 70 emu / g in 1 kOe, a magnetic carrier having a particle diameter of 30 to 80 μm, and a magnetic carrier having a particle diameter of 3 to 80 μm. And a non-magnetic toner in the range of about 8 μm.
1 is applied with a developing bias in which an alternating electric field is superimposed, and the image carrier 1 having an electrostatic latent image is developed using the non-magnetic toner.

(Circulation of Developer and Replenishment of Toner) The circulation of the developer will be described with reference to the schematic diagram of FIG.

(1) On the upstream side of the developer stirring section 402, the developer refluxed from the developer supply section 401 and the developer recovery section 403 and the new toner are carried in, and the stirring member 4
The toner is agitated and mixed by 6, and is conveyed in the developer moving direction indicated by arrow V1.

(2) The mixed developer passes through the third opening 408 on the downstream side of the developer stirring section 402 and is introduced into the upstream side of the developer supply section 401. Developer supply section 401
Inside, the developer is transported to the supply member 44 as shown by the arrow V3 while being transported by the transport member 45 in the developer moving direction shown by the arrow V2.

(3) The supply member 44 does not have a transport function in the direction of the rotation axis, and transports the developer transported from the supply member 44 to the developer carrier 41 as shown by an arrow V4.

(4) The developer on the developer carrier 41 is developed in a developer region facing the image carrier 1. The developer whose toner concentration has decreased after the developing process is removed by the peeling roller 47 of the peeling means.
1 is peeled off as shown by an arrow V5, and moves on a peeling roller 47.

(5) The collected developer on the stripping roller 47 is stripped off by the stripping plate 48 and stored in the developer collecting section 403 as indicated by an arrow V6.

(6) The collected developer stored in the developer collecting section 403 is supplied with new toner from the second toner replenishing means 52 to the toner replenishing opening 410 on the upstream side of the developer collecting section 403. Mixed with. The mixed developer is
It is transported by the rotating recovery member 49 as shown by the arrow V7.

(7) The mixed developer is discharged from the first opening 406 on the downstream side of the developer recovery section 403, and out of the image area on the downstream side of the developer supply section 401 as shown by an arrow V8. It is carried in.

(8) First opening 4 of developer supply section 401
The developer supplied to the cartridge 06 is conveyed as indicated by an arrow V9, and after the toner concentration is detected by the toner concentration sensor TS, passes through the second opening 407 to agitate the developer as indicated by an arrow V10. It is introduced upstream of the part 402.

(9) In the developer agitating section 402, the toner is supplied by the first toner supply means 51 according to the toner concentration detection signal of the toner concentration sensor TS, and the developer joins the arrow V1.

The developer is conveyed in the circulation system as described above, but some of the developer is circulated between the developer supply section 401 and the developer stirring section 402 as indicated by arrows V1, V2, V9, and V10. I do.

(Control of Replenishment of Toner) Developing device 4 of the present invention
Is provided with a first toner supply means 51 connected to the toner supply opening 409 on the upstream side of the developer stirring section 402 and connected to the toner supply opening 410 on the upstream side of the developer collection section 403. The second toner supply means 52 is provided.

The first toner replenishing means 51 replenishes the toner with the control means 9 based on the detection signal from the toner density sensor TS so as to maintain a predetermined density.

The control means 9 calculates the printing rate from the image data at the time of image formation, and when the printing rate is high, the second toner replenishing means 52 uses the toner replenishing opening with a toner replenishing amount corresponding to the printing rate. The toner is supplied from the unit 410 to the developer collecting unit 403, and the developer is controlled to a predetermined toner concentration.

The toner density in the developer recovery unit 403 changes according to the printing rate at the time of image formation, and particularly when an image with a high printing rate such as a solid image is copied, the toner density is extremely reduced. I do.

By supplying a toner supply amount corresponding to the toner consumption amount of the solid image from the second toner supply means 52 to the toner supply opening portion 410 of the developer collecting section 403, the toner density is adjusted as described above. The developer is conveyed to the developer stirring section 402 without extremely lowering.

When the printing rate calculated from the image data is 30
%, The second toner replenishing means 52
As a result, the replenishment toner is sent upstream of the collection member 49 in the developer conveyance direction.

[0083]

[Table 1]

Table 1 shows that 200 sheets of A4 size paper P,
The toner density Tc at the time of continuous copying, the charge amount Q / M,
A developing device before the measure having only the first toner replenishing means 51 for controlling image density (reflection density), fog, and toner scattering;
First toner supply means 51 and second toner supply means 52
And a developing device after the measure having the following.

In the developing device before the countermeasures, an increase in image density, fogging, and toner scattering occurred at a printing rate of 90%.
In the developing device after the countermeasures, at a printing rate of 90%, the toner density Tc, the charge amount Q / M, and the image density were all stable, and fog and toner scattering were eliminated.

FIG. 4 shows a developing device before toner replenishment measures,
FIG. 9 is a characteristic diagram illustrating characteristics of a charge amount Q / M with respect to an image printing rate in a developing device after a toner replenishment measure.

In the developing device having only the first toner replenishing means 51 before the measure, when the copy rate is 30% or more, the charge amount Q / M decreases (see the diagram). In the developed developing device having the first toner replenishing means 51 and the second toner replenishing means 52, the decrease in the charge amount Q / M is eliminated in the case of a copy with a printing rate of 30% or more (see the diagram). ).

That is, the second toner supply means 52
The toner supplied to the upstream portion of the developer collecting section 403 has a long conveying path for mixing and stirring with the developer, and is thus sufficiently stirred and passed through the developer stirring section 402 to the developer supply section 401.
Transported to

Further, by supplying toner in real time to the developer whose toner concentration Tc has decreased in the developing process, the toner in accordance with the consumed toner amount can be replenished in real time.
And the charge amount Q / M is sufficiently increased.

(Evaluation of Uniformity of Solid Black Image and Collection Member) The collection member 49 of the developing device 4 of the present invention is characterized by satisfying the following conditions.

Vs × L × D1 <π × (A ² −B ² ) × p ×
R × K × α / 400 where Vs is the number of rotations of the developer carrier 41 [cm / sec] L is the axial length of the developer carrier 41 (developer conveyance width)
[Cm] D1 is the amount of developer transported per unit area [g] regulated by the developer regulating member 43 and transported onto the developer carrier 41.
/ Cm ² ] D2 collects the developer in the developer collecting section 403 and collects the developer.
The amount of developer fall per unit time from the opening of the developer collection unit [g / sec] when the 9 is rotated at a predetermined number of rotations A is the outer diameter of the collection member 49 [cm] B is the rotation of the collection member 49 Shaft outer diameter [cm] p is the screw pitch of the collecting member 49 [cm] R is the number of rotations of the collecting member 49 [rps] K is the bulk density of the developer [g / cm ³ ] α is the developer transport rate [%] In the developing device 4 that satisfies the above conditions, the developer is completely peeled off from the developer carrier 41 and the new developer is supplied from the developer supply unit 401, so that a uniform image can be obtained. The shape of the collecting member 49 will be described later with reference to FIG.

The method for obtaining the developer transport rate α is as follows. The developer is collected in the developer collecting section 403 and the developer collecting section 4 per unit time when the collecting member 49 is rotated at a predetermined rotation speed.
03 from the first opening 406 of the developer D2 [g / g
sec], and the developer transport rate α is determined from the following equation.

Α = D2 / (π × (A ² −B ² ) × p × R × K) × 400 For example, A = 1.8 cm, B = 0.6 cm, p = 2.5
cm, R = 4.2 rps, K = 1.9 g / cm ³ , developer drop amount D2 = 32 g per unit time
/ Sec, the developer transport rate α is α = 32 / (π × (1.8 ² −0.6 ² ) × 2.5 × 4.
2 × 1.9) × 400∴α = 70.9%. Table 2 below shows the relationship between the uniformity of the solid black image when the amount of developer movement on the developer carrier 41 is changed.
Shown in However, the developer conveyance width L is set to 33 [cm].

[0094]

[Table 2]

The result of the visual evaluation is a result corresponding to the above conditional expression. In addition, the developer collection unit 40 of the above result
The rotation direction of the rotation 3 is opposite to the rotation direction of the developer carrier 41, and is a rotation for transporting the developer in the axial direction along the side surface of the developer collection unit 403 opposite to the developer carrier 41 side. Direction, the backflow to the developer carrier 41 side is small, but in the same direction as the rotation of the developer carrier 41, the backflow increases. It tends to worsen (see Table 3).

[0096]

[Table 3]

Next, when the outer diameter of the collecting member 49 is increased,
Screw pitch p can also be increased at the same rate,
The developer conveyance force is improved. However, the larger the cross-sectional area of the recovery member 49 is, the more advantageous it is. However, since the size of the apparatus is increased, there is a limit to the increase in the outer diameter.

For example, the relationship between the outer diameter A of the screw of the collecting member 49 and the amount D2 of developer falling per unit time is as follows.
As shown below, the developer transfer performance is different. The smaller the outer diameter, the less the amount of developer transported in the axial direction, which is disadvantageous (see Table 4).

[0099]

[Table 4]

Here, the image was formed by setting the developer transport amount to the above-mentioned amount in the developing device 4 having the collecting member 49 having the outer diameter A = 2 cm or less. , The developer transport amount D1 is equal to the developer drop amount D2.
When a larger relationship (D1> D2) is satisfied (for example, A
= 2 cm, the developer conveyance amount setting is 0.049 g / c
m ² ), in which case the developer carrier 4
The phenomenon that the peeling performance of No. 1 was deteriorated and the uniformity was impaired occurred.

Therefore, by taking the following countermeasures, it has become possible to always ensure stable peeling performance.

For example, when the developer carrying amount per unit area of the developer carrier 41 is set to 0.06 g / cm ² or less, the rotation direction of the collection member 49 is opposite to the rotation direction of the developer carrier 41. And the rotation speed of the collection member 49 satisfies the following condition.

For example, Vs = 27 cm / sec, L = 3
3 cm, D1 = 0.06 g / cm ² , A = 2.0 cm,
B = 0.6 cm, p = 2.8 cm, K = 1.9 g / cm
^{3. In} the case of a developing device with α = 67.7%, R> 400 × (Vs × L × D1) / (π × (A ² −B ² )
× p × K × α) ∴ R> 400 × (27 × 33 × 0.06) / (3.1
4 × (2 ² −0.6 ² ) × 2.8 × 1.9 × 67.7) ∴R> 5.19 rps When the rotation speed per second is in the range of R> 5.19 rps, the collection member 49 is removed. When rotated, the amount of falling from the developer collecting section 403 becomes more than 53.5 g / sec.
(See Table 5)

[0104]

[Table 5]

The direction of rotation of the collecting member 49 is changed to the developer carrying member 4.
When the reverse rotation is performed with respect to the rotation direction of 1, the reverse flow of the developer can be reduced by rotating the rotation speed R of the collection member 49 at a rotation speed greater than 5.19 rps, and the developer conveyance amount D1
Is 0.06 g / cm ² and the outer diameter A of the collecting member 49 is 2c.
Even with m, uniformity can be ensured in a solid image.

In a configuration in which the rotation speed of the developer carrier 41 is variable, the collection member 4
It is also necessary to variably control the number of rotations of Nin.

However, the appropriate value of the developer transport amount varies depending on the system, and need not be limited to the above value. Further, the outer diameter of the developer carrying member 41 is 2 cm, and when the outer diameter is small, the rotation speed of the collecting member 49 is set higher than the above.

(Prevention of Backflow of Developer in Developer Recovery Section) FIG.
FIG. 6 is a cross-sectional view of a developing device showing another embodiment of the developer collecting section.

In the vicinity of the collecting member 49, between the stripping roller 47 of the stripping means and the collecting member 49, the developer collecting section 4 is provided.
A developer backflow prevention member 40D or 40E is provided from an upper lid 40C provided above the upper cover 03 to prevent the developer from flowing back to the stripping means. Developer backflow prevention member 40
D and 40E are members arranged orthogonally to the developer conveying direction. The shape of the developer backflow prevention members 40D and 40E is not limited to the shapes shown in FIGS.

Table 6 shows the developer guide ribs 40D or 4D.
The result of studying the developer transport rate α of the developing device 4 provided with 0E is shown.

[0111]

[Table 6]

The above results shown in Table 6 were obtained by confirming that the rotation speed of the recovery member 49 was 4.2 [rps]. By providing the developer backflow prevention member 40D or 40E, the developer conveyance rate α is improved, the developer conveyance amount of the collection member 49 is increased, and the developer that is going to flow back to the developer carrying member 41 side is improved. In order to reduce the flow of the developer, compared to a case where the developer backflow prevention member 40D or 40E is not provided,
Even when the number of rotations of the collection member 49 is set to be low, uniform performance is improved in a solid image. In addition, the performance is further improved by increasing the rotation speed of the collection member 49.

(Recovery Member) FIG. 7 is a side view of the recovery member 49.

The collection member 49 is formed of a double or more spiral screw on the same axis as the rotation shaft 490. The first screw 491 and the second screw 492 have the same outer diameter A and the same screw pitch p. B is the outer diameter of the rotation shaft 490 of the collection member 49.

For each single screw pitch p of the first screw 491 and the second screw 492, the screw pitch between the first screw 491 and the second screw 492 formed in a double helix is p / 2. In addition, it is possible to increase the developer conveyance amount in the rotation axis direction.

[0116]

[Table 7]

Table 7 shows the experimental results of the developer drop amount D2 and the developer transport rate α by the developing device provided with the recovery member 49 composed of the screws 491 and 492 formed in a double helix.

The experimental results shown in Table 7 confirm that the screw rotation speed of the recovery member 49 is 4.2 [rps].

Screws 491 formed in a double helix
492, the developer transport rate α is improved, and the amount of developer transported by the recovery member 49 is improved.
Even in the case where the number of rotations of the collecting member 49 is set lower than the conventional screw shape, the uniform performance in the solid image is improved.

Further, by using the screw rotation speed increase and the developer backflow prevention member 40D (or 40E) together, the developer conveyance amount of the collection member 49 is further improved, and the developing performance is improved.

(Developer Stripping Means) FIG. 8 is an enlarged sectional view of the stripping roller 47 and the stripping plate 48.

At the position where the gap δ between the leading end of the stripping plate 48 and the outer peripheral surface of the stripping roller 47 and the developer t rising from the developer stripping magnetic pole s2 of the stripping roller 47 do not come into contact with the developer, The uniformity of the development is determined by the installation angle θ of the tip of the stripping plate 48 in the rotation direction of the stripping roller 47, with the starting point in the rotation direction of the developer t rising at the agent stripping magnetic pole s2 as the base point. Was confirmed by the experimental results shown in Table 8 below.

[0123]

[Table 8]

[0124]

[Table 9]

The negative direction of the angle θ shown in Tables 8 and 9 above is the direction in which the developer comes into contact with the rising portion of the developer, and the positive direction is the direction in which it does not. Further, in the developer uniformity column, a circle indicates that the developer is uniformly applied to the developer carrier 41,
Good development processing is possible, and △ indicates that development processing is somewhat good. The mark “Δ” indicates that the development processing was slightly poor, and the mark “X” indicates that the development processing was defective.

A gap δ between the tip of the stripping plate 48 and the outer peripheral surface of the stripping roller 47 is set to 0.4 mm or less,
And a magnetic pole s2 for removing the developer of the removing roller 47.
At a position not in contact with the developer t which rises in the direction of rotation, the angle θ in the rotation direction of the peeling roller 47 is set to 30 from the most downstream position in the rotation direction of the developer t which rises in the developer peeling magnetic pole s2. By setting the tip of the peeling plate 48 within the range of °, a uniform developer layer is formed, and good development processing can be performed.

When the tip of the stripping plate 48 is brought into contact with the surface of the stripping roller 47, the setting range of the tip position of the stripping plate 48 is the widest. However, the contact of the stripping plate 48 adversely affects the durability of the surface of the stripping roller 47 and the durability of the developer. Therefore, it is a more preferable setting that the peeling plate 48 is in a non-contact state.

[0128]

[Table 10]

Table 10 shows that the gap δ between the tip of the stripping plate 48 and the outer peripheral surface of the stripping roller 47 was fixed at 0.4 mm, and the range of the tip of the stripping plate 48 (angle θ).
And the magnetic flux density X in the normal direction of the developer stripping magnetic pole S2.
Is the result of experimentally determining the uniformity of development in relation to The evaluation of uniformity of development was made by
The same applies to Δ, Δ, and X.

At a position where the peeling roller 47 does not come in contact with the developer t rising at the developer stripping magnetic pole s2, the starting point is the rotationally most downstream position of the developer t rising at the developer stripping magnetic pole s2. The tip of the stripping plate 48 is set within an angle θ of 30 ° in the rotation direction of the stripping roller 47, and the magnetic flux density X in the normal direction of the developer stripping magnetic pole s2 is determined. By setting it to 600 [Gauss] or less, the developer is reliably peeled off from the developer peeling magnetic pole S2, a uniform developer layer is formed, and good development processing is possible.

(Another Embodiment of Developing Apparatus) FIG. 9 (a)
FIG. 9B is a cross-sectional view of a developing device showing another embodiment of the present invention, and FIG. 9B is an enlarged cross-sectional view of a developer carrier 41 and a peeling plate 48. In addition, about the code | symbol used for drawing, the part which has the same function as FIG. 2 is attached | subjected. Further, points different from the above embodiment will be described.

In the developer collecting section 403 of the developing device 4,
Without a peeling roller, the leading end of the peeling plate 48 faces the vicinity of the developer peeling magnetic pole S2 of the developer carrier 41. The gap δ between the tip of the stripping plate 48 and the outer peripheral surface of the developer carrier 41 is set to 0.4 mm or less, and the tip of the stripping plate 48 is
At a position where the developer t which rises at the developer stripping magnetic pole S2 is not in contact with the developer rising at the developer stripping magnetic pole S2, an angle of 3 degrees from the most downstream position in the rotation direction of the developer t rising at the developer stripping magnetic pole S2.
By setting it within the range of 0 °, almost the same results as the experimental results shown in Table 8 above were obtained.

Further, the installation range (angle θ) of the position of the leading end of the stripping plate 48 is set within a range of 30 ° or less, and
When the magnetic flux density X in the normal direction of the developer stripping magnetic pole S2 is 6
By setting the value to be not more than 00 [Gauss], substantially the same results as the experimental results shown in Table 9 above were obtained.

By the above measures, the performance of stripping off the developer is ensured, so that the uniform performance in a solid image is improved. In addition, the performance is further improved by increasing the rotation speed of the collecting member 49, installing the developer backflow preventing members 40D and 40E, and using a double spiral configuration of the screw of the collecting member 49.

[0135]

According to the developing device of the present invention, the following effects can be obtained.

(1) Regardless of the printing rate, Q / M rise is ensured, a stable image density is always ensured, problems such as fogging and toner scattering are solved, and problems such as developer packing and developer depletion are caused. The occurrence is prevented.

(2) In the case of a low printing rate, since toner replenishment control is performed based on the detection result of the toner density sensor, stable toner density control can be secured, and a stable image density can be obtained. Further, when the printing rate is high, the toner is directly replenished to the developer having the lowered toner density, so that the Q / M rise is secured, the stable image density is always secured, and problems such as fog and toner scattering can be solved.

(3) Particularly, when the printing rate is 30% or more (the amount of toner (primary adhesion amount M / A =
0.8 mg / cm ² ) is 29.7 × 21 × 0.8 ×
0.3 = 150 mg), when toner is supplied at the upstream portion of the stirring and conveying portion, the toner does not rise to a predetermined charge amount Q / M.
Since toner is directly replenished to the developer whose toner density has decreased, the rising of the charge amount Q / M is ensured, a stable image density is always secured, and problems such as fogging and toner scattering can be solved.

(4) Backflow from the developer collecting section to the developing roller side can be prevented. In addition, the transportability in the axial direction can be improved without greatly increasing the cross-sectional area of the developer recovery section and the number of rotations of the recovery member, and there is no problem of density unevenness such as development ghost, and it is always stable. Thus, a uniform image can be obtained.

(5) Problems such as a decrease in toner density and a decrease in image density which occur during continuous mass printing are eliminated.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a color copying machine including an image forming apparatus main body and an image reading device.

FIG. 2 is a central sectional view of the developing device according to the present invention.

FIG. 3 is a schematic diagram illustrating circulation of a developer in a developing device.

FIG. 4 is a graph showing the relationship between the developing device before toner replenishment and the toner after replenishment.
FIG. 3 is a characteristic diagram showing characteristics of / M.

FIG. 5 is a cross-sectional view of a developing device showing another embodiment of a developer collecting section.

FIG. 6 is a cross-sectional view of a developing device showing still another embodiment of a developer collecting section.

FIG. 7 is a side view of the collection member.

FIG. 8 is an enlarged sectional view of a peeling roller and a peeling plate.

FIG. 9 is a sectional view of a developing device according to another embodiment of the present invention, and an enlarged sectional view of a developer carrier and a peeling plate.

FIG. 10 is a central sectional view of a conventional developing device.

[Explanation of symbols]

 1, 1Y, 1M, 1C, 1K Image carrier (photoconductor) 4, 4Y, 4M, 4C, 4K Developing device 5Y, 5M, 5C, 5K Toner replenishing means 40 Developing device main body 40C Top lid 40D, 40E Developer backflow prevention Member 401 Developer supply section 402 Developer stirring section 403 Developer recovery section 409, 410 Toner supply opening 41 Developer carrier (developing sleeve) 42 Magnetic field generating means (magnet roll) 43 Developer regulating member (spike plate) ) 44 Supplying member (paddle wheel) 45 Conveying member (conveying screw) 46 Stirring member (stirring screw) 47 Stripping roller 47A Rotating member 47B Magnet 48 Stripping plate 49 Collection member (recovery screw) 490 Rotating shaft 491 First Screw 492 Second screw 51 First toner replenishing means 52 Second toner supplement Means S2, s2 developer stripping magnetic pole S3 developer receiving pole TS toner concentration sensor (toner concentration detecting means) theta angle δ gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/08 G03G 9/10 9/09 15/06 101 9/10 15/09 Z 15/06 101 9 / 08 361 15/09 15/08 507E F-term (reference) 2H005 AA21 BA00 EA02 EA05 FA02 2H031 AC03 AC08 AC14 AC20 AC30 AE01 AE02 BA05 BA09 CA11 CA13 DA01 FA01 2H073 AA02 BA04 BA13 BA45 CA03 CA22 2H077 AA02 AB AC03 AC04 AC12 AC16 AD02 AD06 AD13 AD17 AD31 AD32 AD36 DA10 DA12 DB02 DB08 EA03 GA13

Claims (17)

[Claims] 1. A developer carrying member facing an image carrying member carrying an electrostatic latent image, a developer supply section for supplying a developer to the developer carrying body, and a developer supplying a developer to the developer supplying section. A developer agitating section for agitating and supplying the developer, a peeling means for peeling off the developed developer on the developer carrying member, and collecting the developer peeled off by the peeling means to remove the developer A developer collection unit that conveys the developer to a downstream portion of the non-image forming area of the supply unit; a first toner replenishing unit that supplies replenishment toner near the upstream of the developer agitating unit in a developer conveyance direction; A second toner replenishing means for feeding replenishment toner upstream in a developer transport direction. 2. A developing device comprising: a developer supply unit configured to supply a developer to a developer carrier facing an image carrier that carries an electrostatic latent image; a developer regulating member regulating the developer to a fixed amount; A developer is removed from the developer carrier by a peeling means and sent to a developer collecting section, and a second toner replenishing means provided upstream of the developer collecting section. By replenishing the toner, the toner and the developer are agitated by the collecting member in the developer collecting section and transported from the downstream to the downstream of the non-image forming section of the developer supply section,
After the toner concentration is detected by the toner concentration detecting means provided at the downstream portion, the toner is conveyed from the downstream portion of the non-image forming portion of the developer supply portion to the upstream portion of the developer agitating portion, and provided near the upstream portion. The first toner replenishing unit replenishes the toner under the control of the toner concentration detecting unit, agitates the replenished toner and the developer by a stirring member in a developer agitating unit, and conveys the developer to a downstream portion. A developing device, wherein a one-way flow developer circulation path is formed to transport and supply the developer to an upstream portion of the supply section. 3. The developing device according to claim 1, wherein the developer carrier has a developer peeling magnetic pole of the same polarity and a developer receiving magnetic pole. 4. The peeling means is disposed opposite to the developer carrying member and has a plurality of magnetic poles therein, and a peeling roller which comes into contact with or comes close to an outer peripheral surface of the peeling roller. The developing device according to claim 1, comprising a member. 5. A developer carrier facing an image carrier carrying an electrostatic latent image, a developer supply unit for supplying a developer to the developer carrier, and a developer supplied to the developer supply unit. A developer agitating section for agitating and supplying the developer, a peeling means for peeling off the developed developer on the developer carrying member, and collecting the developer peeled off by the peeling means to remove the developer A developer collection unit that conveys the developer to a downstream portion of the non-image forming area of the supply unit; a first toner replenishing unit that supplies replenishment toner near the upstream of the developer agitating unit in a developer conveyance direction; A second toner replenishing unit that supplies replenished toner to an upstream portion in a developer transport direction; and a toner density sensor provided downstream of the developer supply unit in the developer transport direction.
The first toner replenishing unit performs toner replenishment based on a detection signal from the toner density sensor, and the second toner replenishing unit performs at least a high printing ratio image formation based on a printing ratio calculated from image data. A developing device controlled to supply toner. 6. When the printing rate calculated from the image data is determined to be 30% or more, the second toner replenishing unit supplies replenished toner upstream of the developer collection unit in the developer transport direction. 6. The method according to claim 5, wherein
3. The developing device according to claim 1. 7. A developer is supplied to a developer carrier facing an image carrier carrying an electrostatic latent image by a supply member, and the developer is regulated to a fixed amount by a developer regulating member. After processing, the developer after the development processing is peeled off from the developer carrier by a peeling means and sent to a developer collecting section, and the developer is stirred by a collecting member in the developer collecting section and developed from a downstream section. The developer is transported to the downstream portion of the non-image forming area of the developer supply portion, is transported from the downstream portion to the upstream portion of the developer agitating portion, and is replenished with toner by toner replenishing means provided near the upstream portion. A developing device that stirs the developer with a stirring member in a developer stirring unit and conveys the developer to a downstream portion, and further conveys the developer to a supply member in a developer supply unit, wherein the collection member satisfies the following condition: A developing device, characterized in that: Vs × L × D1 <π × (A ² −B ² ) × p × R × K × α /
400 α = D2 / (π × (A ² −B ² ) × p × R × K) × 400 where Vs is the peripheral speed of rotation of the developer carrier [cm / sec] L is the axis of the developer carrier D1 is a developer conveyance amount per unit area [g / cm] regulated by a developer regulating member and conveyed on a developer carrier.
² ] D2 is the amount of developer falling per unit time [g / sec] from the downstream opening of the developer collecting unit when the developer is stored in the developer collecting unit and the collecting member is rotated at a predetermined rotation speed. Is the outer diameter of the collecting member [cm] B is the outer diameter of the rotating shaft of the collecting member [cm] p is the screw pitch of the collecting member [cm] R is the number of revolutions per second of the collecting member [rps] K is the developer Bulk density [g / cm ³ ] α is developer transport rate [%] 8. A developer is supplied to a developer carrier facing an image carrier carrying an electrostatic latent image by a supply member, and the developer is regulated to a fixed amount by a developer regulating member. Processing, the developer after the development processing is peeled off from the developer carrier by a peeling means and sent to a developer recovery section, and the developer is stirred by a recovery member in the developer recovery section and the developer is removed from a downstream portion. The developer is supplied to a downstream portion of the non-image forming area of the developer supply portion, is transported from the downstream portion to an upstream portion of the developer agitating portion, and is supplied with toner by toner replenishing means provided near the upstream portion. And a developer agitated by a stirring member in a developer stirring section and conveyed to a downstream portion, and further conveyed to an upstream portion of the supply member in a developer supply section, in the vicinity of the collection member. Between the stripping means and the collection member A developer backflow prevention member protruding from an upper lid for closing the upper part of the developer recovery section, wherein the developer recovered by the recovery member is regulated by the developer backflow prevention member, and the developer is peeled off. A developing device that does not flow backward to the means. 9. A developer is supplied to a developer carrier facing an image carrier carrying an electrostatic latent image by a supply member, and the developer is regulated to a fixed amount by a developer regulating member. Processing, the developer after the development processing is peeled off from the developer carrier by a peeling means and sent to a developer recovery section, and the developer is stirred by a recovery member in the developer recovery section and the developer is removed from a downstream portion. The developer is supplied to a downstream portion of the non-image forming area of the developer supply portion, is transported from the downstream portion to an upstream portion of the developer agitating portion, and is supplied with toner by toner replenishing means provided near the upstream portion. And a developer agitated by a stirring member in a developer stirring section and transported to a downstream portion, and further transported to an upstream portion of a transporting member in a developer supply section, wherein the stripping means is Releases residual developer on the developer carrier An image agent stripping magnetic pole, and a plurality of magnets installed and fixed in proximity to the developer stripping magnetic pole of the developer carrying member, and holding the developer on a rotatable rotating member. A peeling roller that peels off the developer from the developer carrier and conveys the developer to the collecting member; and a developer peeling roller of the peeling roller, which is disposed in the developer collecting portion in proximity to the developer peeling magnetic pole. A gap between the tip of the stripping plate and the outer peripheral surface of the stripping roller is set to 0.4 mm or less, and the tip of the stripping plate is At a position where it does not come in contact with the developer that rises at the developer stripping magnetic pole, the angle is set within a range of 30 ° in the rotation direction from the most downstream position in the rotation direction of the developer that rises at the developer stripping magnetic pole. A developing device, characterized in that: 10. The developing device according to claim 9, wherein the magnetic flux density in the normal direction of the developer stripping magnetic pole is 600 gauss or less. 11. A developer is supplied to a developer carrier facing an image carrier carrying an electrostatic latent image by a supply member, and the developer is regulated to a fixed amount by a developer regulating member. Processing, the developer after the development processing is peeled off from the developer carrier by a peeling means and sent to a developer recovery section, and the developer is stirred by a recovery member in the developer recovery section and the developer is removed from a downstream portion. The developer is supplied to a downstream portion of the non-image forming area of the developer supply portion, is transported from the downstream portion to an upstream portion of the developer agitating portion, and is supplied with toner by toner replenishing means provided near the upstream portion. And a developer agitated by a stirring member in a developer stirring section and transported to a downstream portion, and further transported to an upstream portion of the supply member in a developer supply section, wherein the stripping means is: Releases residual developer on the developer carrier A developer peeling magnetic pole, and a peeling plate disposed in the developer collecting portion adjacent to the developer peeling magnetic pole, and a tip end of the peeling plate and an outer periphery of the developer carrier. 0.4mm gap with the surface
At the position set below, the tip of the stripping plate is raised with the developer stripping magnetic pole at a position where it does not come into contact with the developer that is raised with the developer stripping magnetic pole of the developer carrier. An angle of 3 from the most downstream position in the rotational direction of the developer in the rotational direction.
A developing device characterized by being set within a range of 0 °. 12. The developing device according to claim 11, wherein the magnetic flux density in the normal direction of the developer stripping magnetic pole is 600 gauss or less. 13. The developing device according to claim 9, wherein a rotation direction of the collection member is a rotation in a direction opposite to a rotation direction of the developer carrier. 14. The developing device according to claim 9, wherein the collecting member is formed of a double or more spiral portion on the same rotation shaft. 15. The non-magnetic toner according to claim 1, wherein the developer has a magnetization in a range of 20 to 70 emu / g and a particle size in a range of 3 to 8 μm in 1 kilooersted of the magnetic carrier. A component developer, applying a developer bias in which an alternating electric field is superimposed on the developer carrier, and developing the image carrier having an electrostatic latent image with the non-magnetic toner. Claims 1, 2, 5, 7,
12. The developing device according to any one of 8, 9, and 11. 16. A developing device according to claim 1, further comprising: a charging device for forming an electrostatic latent image on the image carrier; and a toner image formed by the developing device. An image forming apparatus comprising: a transfer unit that transfers a recording sheet to a recording sheet; a sheet feeding unit that feeds the recording sheet to the transfer unit; and a fixing unit that fixes a transfer image formed on the recording sheet. . 17. The developing device according to claim 1, wherein a charging device for forming an electrostatic latent image on the image carrier, a plurality of exposure devices, and developers of different colors are stored. Apparatus, transfer means for transferring the toner image formed by the developing device to recording paper, paper feeding means for feeding the recording paper to the transfer means, and fixing for fixing the transferred image formed on the recording paper An image forming apparatus which forms a plurality of color toner images on the recording paper by means.