JPH10198173A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently mix carriers and toner whose grain sizes are small by returning a surplus developer to a second developer stirring region with a flow straightening member and stirring the surplus developer and a supplied fresh developer, in this region. SOLUTION: This developing device consists of the flow straightening member 56 for returning the surplus developer to the second developer stirring region 44, first and second carrying members R1 and R2 for carrying a two-component developer, while stirring it, etc. At this time, the developer supplying port of a developing container 41 is provided in a part, nearer to the upstream side than a position where the developer drops from the flow straightening member 56 to the second developer stirring region 44. The toner supplied from the developer supplying port, of the developing container 41 is stirred/carried by the second/first carrying members R2 and R1. The developer supplied by the flow straightening member 56 drops from above the supplied toner, so that a mixing operation by the up and down movements of the toner newly supplied from a supplying position and the developer supplied by the flow straightening member 56 is added. Therefore, the toner and carriers whose grain sizes are small can be mixed more than heretofore.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed on an image carrier into a toner image in an image forming apparatus such as an electrophotographic copying machine or a laser printer. And a developing device using a two-component developer composed of a carrier.

[0002]

2. Description of the Related Art In a color image forming apparatus which has been in high demand in recent years, a method of superposing a plurality of color toners stored in a plurality of developing units on a recording medium is generally used. The following method is conventionally known as the above method. (a) Rotary method: a method in which a rotating body on which a plurality of developing devices are mounted is rotated, and developing devices of a plurality of colors are sequentially opposed to or contact with a photosensitive member to perform development. (b) Retract system: A system in which a plurality of developing units are arranged so as to be close to and retractable from the photoconductor, and are sequentially brought into contact with the photoconductor to perform development. (c) Tandem system: a system in which a set of one image carrier and one or a plurality of developing units arranged around the same is arranged in series and developed. In these types of developing units, a developing method using a two-component developer composed of a non-magnetic toner and a magnetic carrier is often used. In this method, it is necessary to uniformly mix the newly supplied non-magnetic toner with the carrier before reaching the developing area with the image carrier, and to sufficiently charge the toner required for development.

Conventionally, a toner replenishing port is provided near the start of transport of a transport agitating member farthest from a developing roll, and two transporters which rotate the replenished developer in opposite directions in the developing device. The developer is circulated in the developing container by the stirring member, and the charge and the uniformity of the toner and the carrier are performed by stirring in the circulation path before the developer adheres to the image carrier. At the same time, the toner and the carrier are transported to a developing roll to form a layer of a developer on the surface of the developing roll, and a final layer is formed and charged by a developer transport amount regulating member. Develop in the area.

[0004]

As described above, a copier,
With the spread of full-color printers, demands for higher image quality from the market are increasing. Among various items of image quality improvement, especially in a color photographic image, the granularity of toner has been regarded as a major factor in determining image quality.
In particular, in digital images, it is important to faithfully develop each pixel of an electrostatic latent image formed by a laser beam, and it is necessary to uniformly develop toner having the smallest possible diameter and uniform particle diameter. According to the inventor's research,
Select the developing conditions to suppress the selective development of the toner particle size (development where the toner having a large particle size is easily developed and the toner having a small particle size is difficult to be developed is not developed) and the particle size distribution of the toner is narrowed. Also, it was found that when the particle size was made smaller than before, very good image quality was obtained, especially in the low density image area.

In the magnetic brush developing system using a two-component developer, a process of developing an electrostatic latent image on an image carrier into a toner image is performed in the front side in the process direction (upstream in the rotation direction of the image carrier). ) Has a low-density image, and an adjacent low-density part is missing in an image in which a high-density image part is adjacent to the process direction side (downstream in the rotation direction of the image carrier), or a rear end in the low-density image part However, there is a problem of an image quality defect that the image is missing. In response to this, by reducing the particle size of the carrier to 50 μm or less than before,
It has been found to be greatly improved, and very good image quality can be provided.

However, when a carrier smaller than 20 μm is used as a small-diameter carrier, powder fluidity deteriorates, and therefore, there is a problem that the admix (mixing) property with the toner becomes extremely poor. Therefore, if a small-diameter carrier having a size of 20 μm or more is used, the admix property with the toner does not deteriorate. The fluidity of the developer can be measured by making a small hole in the bottom surface of the container containing the developer and measuring a speed at which a certain amount of the developer is discharged from the hole (developer falling speed). . The higher the developer falling speed, the higher the fluidity of the developer. When the particle size of the carrier is small, the fluidity deteriorates due to an increase in the area in contact with the surface of the carrier. In addition, when the weight of the carrier is reduced, the falling speed of the developer is reduced, so that the fluidity is deteriorated. Therefore, when the small-diameter carrier and the small-diameter toner are mixed, the fluidity of the developer is deteriorated. If the fluidity of the carrier is 30 sec / 50 g or more (measured value according to JISZ2502 measurement method) or more, the fluidity is very poor, so that the toner and the carrier are hardly mixed, the admix property is deteriorated, and the toner cannot be charged sufficiently. In particular, when a high-density image sample is continuously copied, a large amount of replenished toner is not mixed and charged sufficiently uniformly, so that density unevenness and fogging of a background portion (a phenomenon that toner adheres to a white portion) occur. There is a problem. Therefore, a developing device for improving the admix and developing with high image quality is required even when the fluidity of the carrier is 30 sec / 50 g or more.

Further, as described above, when the size of the developing device is reduced due to the miniaturization of the printer and the like, the amount of developer contained in the developing device is small, so the absolute amount of toner in the developing device is small, and the circulation speed of the developer must be increased. No. Accordingly, the time required for the replenishment toner to circulate in the developing device and reach the image carrier is shortened, and the amount of toner exchanged with the developer per unit number of copies increases, so that the toner is mixed and charged sufficiently uniformly. There is a problem of disappearing.

As a method for solving the above problem, the following technique (J01) is known. (J01) (Technology described in Japanese Patent Publication No. 2-35985) The following technique is described in this publication. (A) picking up a developer on a developing sleeve, transferring the developer to a wedge-shaped gap formed by the developing sleeve and the developer guide plate, and regulating the layer thickness of the developer by a doctor blade; Due to the friction between the developer and the side surface of the developing sleeve, a developer transported at a low speed and a developer transported at a high speed are generated. A technique in which these developers are agitated in the process of being conveyed and charge the developers. (B) A technique for improving the admix performance by circulating surplus developer accumulated upstream of a doctor blade of a developing sleeve to a supply rotating member or a developer pool.

(Problem of (J01)) The technique described in (J01) has the following problem. In the case of (a), the distance from the developer adhering to the surface of the developing roll to the doctor blade (developer conveying amount regulating member) is shortened due to the downsizing of the developing roll, and the developer is agitated during this time. The effect is reduced, and the developer is not sufficiently uniformly mixed and charged, so that the admix performance (mixing performance) as a developing container is reduced. In the case of (b), the surplus developer which has flowed back into the supply agent or the developer pool is supplied to the developing roll without being agitated. Is not sufficiently uniformly mixed and sufficient charging is not performed, so that the density unevenness and the fog occur in the background portion. When a developer having a small particle size and a small charge amount is used, the problem caused by insufficient stirring of the developer and the charge amount becomes even more serious.

The present invention has been made in view of the above circumstances, and has the following content as an object. (O01) To provide a developing device capable of sufficiently mixing a carrier and a toner having a small particle diameter and sufficiently charging even a small developing device.

[0011]

Next, the present invention devised to solve the above-mentioned problems will be described. Elements of the present invention are used to facilitate correspondence with elements of the embodiments described later. , The reference numerals of the elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(1st invention) In order to solve the aforementioned problem,
The developing device of the first invention of the present application has the following requirements: (A01) a cylindrical developing sleeve (2) for conveying a two-component developer composed of a toner and a carrier to a developing area (Q2); R0b) and the developing sleeve (R0b)
A plurality of magnetic poles (N1, S1,
A developing roll (R0) provided with a magnet roll (R0a) having N2, S2, and N3); (A02) a developing roll accommodating section (42) for accommodating the developing roll (R0); and a surface of the developing roll (R0) A developer transport amount regulating member (55) for regulating the amount of the two-component developer adhered to the developing area (Q2) and transported to the developing area (Q2); ), A first developer stirring area (43) extending in the axial direction, and disposed on the opposite side to the developing roll (R0) adjacent to the first developer stirring area (43), and both ends (E) in the axial direction. Are separated from the first developer stirring area (43) by a partition wall (45), and both ends (E) in the axial direction are connected to the first developer stirring area (43) and the partition wall is formed. (45) and the outer wall of the container extending along the partition wall (45). A developer developer container (41) having a second developer stirring area (44) formed therein, a developer supply port (48) for replenishing a new developer inside the container, and (A03) the developer transport amount regulating member (55). ) Returns the excess developer generated on the upstream side to the second developer stirring area (44), and is disposed opposite to the surface of the developing roll (R0) and close to the surface of the developing roll (R0). A rectifying member (56; 63) which comes into contact with the two-component developer conveyed while being adhered to the surface of the developing roll (R0); and (A04) is disposed in the first developer stirring area (43) to perform two-component development. A first transport member (R1) for stirring the developer while transporting the developer in the axial direction of the developing roll (R0), (A05) being disposed in the second developer agitating region (44) for transferring the two-component developer to the first transport member; A second transport member that stirs while transporting in the opposite direction to (R1) R2), (A06) an average particle diameter of 20μm or more, 50 [mu] m
The following carrier.

In the first aspect of the invention, as the developer supplied from the developer supply port (48), it is possible to use a two-component developer having a carrier and a toner, or a developer consisting only of a toner. is there.

(Operation of the First Invention) In the developing device of the first invention of the present application having the above-mentioned features, the developing roll accommodating portion (42) accommodating the developing roll (R0) of the developing container (41).
The first transport member (R) disposed in the first developer stirring area (43) extending in the axial direction of the developing roll (R0) adjacent to the first transport member (R0)
1) means that the toner and the average particle diameter are 20 μm or more and 50 μm
The two-component developer composed of m or less carriers is stirred while being transported in the axial direction of the developing roll (R0). The first developer stirring area (43) is connected to both ends (E) in the axial direction, and is formed between the partition wall (45) and a container outer wall extending along the partition wall (45). Developer stirring area (4
The second transport member (R2) arranged in 4) stirs while transporting the two-component developer in the opposite direction to the first transport member (R1). The two-component developer agitated while transported is a magnetic force of a magnet roll (R0a) having a plurality of magnetic poles (N1, S1, N2, S2, N3) on a cylindrical surface arranged inside a developing sleeve (R0b). And adheres to the surface of the cylindrical developing sleeve (R0b) and is conveyed to the developing area (Q2). The two-component developer makes uniform the transport unevenness by contacting a portion of the rectifying member (56; 63) arranged opposite to the surface of the developing roll (R0) close to the surface of the developing roll (R0). You. Further, the rectifying member (5)
6; 63), an appropriate pressure and frictional force are applied to the developer by the portion close to the surface of the developing roll (R0) and the surface of the developing roll (R0), so that the toner can be charged.

Excess developer generated on the upstream side of the developer conveying amount regulating member (55) is returned to the second developer stirring area (44) by the flow regulating member (56; 63). The returned excess developer is used by being stirred with the new developer supplied from the developer supply port (48) in the second developer stirring area (44). As a result, fogging and uneven density of a toner having a small particle diameter and a carrier having an average particle diameter of 20 μm or more and 50 μm or less which are indispensable for using a small developing device and improving the image quality are prevented, and a good image is obtained. can get.

(Second invention) In order to solve the above problems,
The developing device according to the second invention of the present application has the following requirements, and (B01) a cylindrical developing sleeve (B01) for transporting a two-component developer composed of a toner and a carrier to a developing area (Q2). R0b) and the developing sleeve (R0b)
A plurality of magnetic poles (N1, S1,
A developing roll (R0) provided with a magnet roll (R0a) having N2, S2, and N3); (B02) a developing roll accommodating section (42) accommodating the developing roll (R0); and a surface of the developing roll (R0). A developer transport amount regulating member (55) for regulating the amount of the two-component developer adhered to the developing area (Q2) and transported to the developing area (Q2); ), A first developer stirring area (43) extending in the axial direction, and disposed on the opposite side to the developing roll (R0) adjacent to the first developer stirring area (43), and both ends (E) in the axial direction. Are separated from the first developer stirring area (43) by a partition wall (45), and both ends (E) in the axial direction are connected to the first developer stirring area (43) and the partition wall is formed. (45) and the outer wall of the container extending along the partition wall (45). A developer developer container (41) having a second developer stirring area (44) formed therein, a developer supply port (48) for supplying new developer into the container, and (B03) the developer transport amount regulating member (55). ) Returns the excess developer generated on the upstream side to the second developer stirring area (44), and is disposed opposite to the surface of the developing roll (R0) and close to the surface of the developing roll (R0). A rectifying member (56; 63) which comes into contact with the two-component developer conveyed while being adhered to the surface of the developing roll (R0); (B04) a two-component developing device arranged in the first developer stirring area (43); A first transport member (R1) for agitating while transporting the developer in the axial direction of the developing roll (R0); (B05) a two-component developer disposed in the second developer agitating region (44) for transporting the two-component developer to the first transport member; A second transport member that stirs while transporting in the opposite direction to (R1) R2), (B06) 30sec / 50g or more of the carriers fluidity JISZ2502 assay.

In the second invention, as the developer supplied from the developer supply port (48), it is possible to use a two-component developer having a carrier and a toner, or a developer consisting only of a toner. is there.

(Operation of the Second Invention) In the developing device of the second invention of the present application having the above-described features, the developing roll housing section (42) for housing the developing roll (R0) of the developing container (41).
The first transport member (R) disposed in the first developer stirring area (43) extending in the axial direction of the developing roll (R0) adjacent to the first transport member (R0)
In 1), a two-component developer composed of a toner and a carrier having a fluidity of 30 sec / 50 g or more according to JISZ2502 is stirred while being conveyed in the axial direction of the developing roll (R0).
The first developer stirring area (43) and both ends in the axial direction (E)
And the partition wall (45) and the partition wall (45)
A second transport member (R2) disposed in a second developer stirring area (44) formed between the outer peripheral wall of the container and the outer wall of the container.
Agitates while transporting the two-component developer in a direction opposite to the first transport member (R1). The two-component developer agitated while being conveyed has a plurality of magnetic poles (N1, S1, N2, S2, N2) on a cylindrical surface disposed inside the developing sleeve (R0b).
N3) is applied to the surface of the cylindrical developing sleeve (R0b) by the magnetic force of the magnet roll (R0a) having N3), and is conveyed to the developing area (Q2). The two-component developer includes a rectifying member (56) disposed opposite to the surface of the developing roll (R0).
63) The unevenness of conveyance is made uniform by contacting the portion close to the surface of the developing roll (R0). In addition, a portion of the rectifying member (56; 63) close to the surface of the developing roll (R0) and the surface of the developing roll (R0) apply an appropriate pressure and frictional force to the developer, so that the toner is charged. Can be.

Excess developer generated on the upstream side of the developer conveying amount regulating member (55) is returned to the second developer stirring area (44) by the rectifying member (56; 63). The returned excess developer is used by being stirred with the new developer supplied from the developer supply port (48) in the second developer stirring area (44). As a result, even if a small developing device is used and a toner having a small particle diameter which is indispensable for improving the image quality and a carrier having a fluidity of 30 sec / 50 g or more according to JISZ2502 measurement method is used, fogging and density unevenness are generated. And a good image is obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1 of the first invention) Embodiment 1 of the developing device of the first invention of the present application is characterized in that the first invention has the following requirements. (A07) The developer supply The developing container (41), wherein the opening (48) is provided on the upstream side of a position where the developer falls from the rectifying member (56; 63) to the second developer stirring area (44). (Operation of the First Embodiment of the First Invention) In the first embodiment of the first invention of the present application having the above configuration, the developing container (4
The developer supply port (48) of 1) is provided on the upstream side from the position where the developer falls from the rectifying member (56; 63) to the second developer stirring area (44). Developing container (4
The toner supplied from the developer supply port (48) of 1) is stirred and transported by the second and first transport members (R2, R1). The developer replenished by the rectifying member (56; 63) falls from above the replenished toner.
The mixing operation by the vertical movement of the toner replenished from the replenishing position and the developer replenished by the rectifying member (56; 63) is added, so that the toner and the average particle diameter are 20 μm.
It is possible to mix carriers of m or more and 50 μm or less more than ever.

(Embodiment 1 of the Second Invention) The second embodiment of the present application
Embodiment 1 of the developing device of the invention is characterized in that the second invention has the following requirements. (B07) The developer supply port (48) is provided in the second developer stirring area (4).
The developing container (41) provided on the upstream side from the drop position of the surplus developer from the rectifying member (56; 63) to 4). (Operation of the Second Embodiment of the Second Invention) In the first embodiment of the second invention of the present application having the above-described configuration, the developing container (4
The developer supply port (48) of 1) is provided on the upstream side from the position where the developer falls from the rectifying member (56; 63) to the second developer stirring area (44). Developing container (4
The toner supplied from the developer supply port (48) of 1) is stirred and transported by the second and first transport members (R2, R1). The developer replenished by the rectifying member (56; 63) falls from above the replenished toner.
The mixing operation by the vertical movement of the toner replenished from the new replenishing position and the developer replenished by the rectifying member (56; 63) is added, and the toner and the fluidity are reduced according to JISZ.
The carrier of 30 sec / 50 g or more can be mixed more than ever by the 2502 measurement method.

[0022]

Next, examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In order to facilitate understanding of the following description, arrows X, Y,
The orthogonal coordinate axes X axis, Y axis, and Z axis are defined in the Z direction, and the arrow X direction is forward, the arrow Y direction is left, and the arrow Z direction is upward. In this case, the direction opposite to the X direction (front) (−X direction) is backward, the direction opposite to the Y direction (left) (−Y direction) is right, and the direction Z (upward) is opposite (−Z direction). Is below. Also referred to as the front-rear direction or the X-axis direction including the front (X direction) and the rear (-X direction), and the left-right direction or the Y-axis direction including the left (Y direction) and the right (-Y direction). Good,
It is referred to as a vertical direction or a Z-axis direction including the upper part (Z direction) and the lower part (-Z direction). Furthermore, in the figure, those with "•" in "○" mean arrows pointing from the back of the paper to the front, and those with "x" in "○" are from the table on the paper. It shall mean an arrow pointing to the back.

(Embodiment 1) FIG. 1 is an overall explanatory view of an image forming apparatus provided with a developing apparatus according to Embodiment 1 of the present invention. FIG.
FIG. 4 is an enlarged explanatory view of the developing device shown in FIG.
FIG. 2 is a sectional view taken along line II. FIG. 3 is an enlarged explanatory view of the developing device shown in FIG. 1, and is a sectional view taken along line III-III of FIG. 4 is an explanatory view of the developing container shown in FIG. 2, FIG. 4A is a perspective view of a developing device, and FIG. 4B is a perspective view of a state in which a developer supply member is removed from the developing device. FIG. 5 is a sectional perspective view of a main part of a developer discharge portion of the developing container shown in FIG. FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 7 is a perspective view of the rectifying member of the developing container. In FIG. 1, an image forming apparatus U includes a digital copying machine U1 as an image forming apparatus main body having a platen glass (transparent platen) A1 on an upper surface, and the platen glass A1.
An automatic document feeder U2 detachably mounted thereon is provided. The automatic document feeder U2 has a document feed tray TRk on which documents Gi (i = 1, 2,..., N,..., Not shown) of various sizes to be copied are stacked. I have. The document placed on the document feed tray TRk is transported to a copy position on the platen glass A1, and the copied document Gi is discharged to the document discharge tray TRh.

The copying machine U1 has a UI (user interface), an image input terminal IIT (hereinafter, referred to as IIT) as an image reading unit and an image as an image recording operating unit which are sequentially arranged below the platen glass A1. Output Terminal IOT (I
OT) and an IP provided between the IIT and the IOT.
S (image processing system).

The UI is a section for the user to input an operation command signal such as copy start and the like, and has a display section, a copy start button, a copy set number input key and the like. The display section displays information relating to the current setting state of the image forming apparatus U. An IIT as an original reading device disposed below the transparent platen glass A1 on the upper surface of the copying machine main body U1 includes an exposure system registration sensor (platen registration sensor) Sp and an exposure optical system 1 arranged at a platen registration position (OPT position). have. The exposure optical system 1 has a movable lamp unit 2, and the lamp unit 2 is configured by integrating a lamp 3 for illuminating a document and a first mirror 4. Further, the exposure optical system 1 has a movable mirror unit 5 that moves at half the speed of the lamp unit 2. This moving mirror unit 5
Is composed of a second mirror 6 and a third mirror 7.

Then, the lamp unit 2 moves in the left-right direction (Y-axis direction) in FIG. 1 in parallel with the original, and the moving mirror unit 5 moves at half the moving speed of the lamp unit 2. When the document Gi is moved by a distance of 1/2, the distance between the document Gi and the lens 8 is kept constant, and during that time, the reflected light of the document Gi illuminated by the lamp 3 passes through the exposure optical system 1. And is converged on a CCD (solid-state image sensor). The CCD
Has a function of converting the original reflected light converged on the imaging surface into an electric signal.

The IPS has image reading data output means 11 for adjusting the gain of an analog electric signal of a read image obtained by the CCD of the IIT, converting the analog signal into a digital signal, performing shading correction and the like, and outputting the digital signal. ing. The IPS has a write image data output unit 12 to which the image read data output from the image read data output unit 11 is input, and the write image data output unit 12 temporarily stores the image data. It has an image memory 13 to be used. The write image data output means 12 has a function of performing data processing such as density correction and enlargement / reduction correction on the input image read data and outputting the image read data to the IOT as write image data (laser drive data). ing.

The IPS write image data output means 12
The laser drive signal output device 14 of the IOT to which the image write data (laser drive data) output by the IOT is input, outputs a laser drive signal corresponding to the input image data to an ROS (optical write scanning device, that is, a latent image). Forming device). The ROS scans an electrostatic latent image writing position Q1 on the surface of the rotating image carrier 16 with a laser beam modulated by the input laser drive signal. The image carrier 16
Around the peripheral image writing position Q1
A charging charger 17 is disposed upstream of the developing device D, a developing device D is disposed at a developing position Q2 sequentially, and a transfer device 19 is disposed at a transfer position Q3 downstream of the latent image writing position Q1. Further, a cleaner unit 20 is disposed downstream thereof. The developing position Q2 and the transfer position Q3
Between them, a toner image density sensor SNd for detecting the density of a density detection toner image (that is, a patch) having a small area formed on the image carrier 16 is arranged.

In the copying machine main body U1, a first paper supply tray T1 and a second paper supply tray T2 for sequentially storing sheets, an intermediate tray for temporary stock used for double-sided copying, etc. T0, a third paper supply tray T3, a fourth paper supply tray T4, and a fifth paper supply tray T5 for storing a large number of sheets are detachably stored. And the first paper feed tray T
1, a first delivery roll R11, a first separating roll device R12, and a first takeaway roll device R13 are provided, and a first feed sensor SN1 is provided in front of the first takeaway roll device R13. Are arranged. The same delivery rolls R21,... R51, discarding roll devices R22,.
Takeaway roll devices R23,... R53, feed sensors SN2,. Further, a delivery roll R01, a takeaway roll device R03, a feed sensor SN0, and the like are provided for the intermediate tray T0. The intermediate tray T0 is a tray used when circulating the recording sheet (hereinafter referred to as a sheet) S on which the first copy has been performed at the time of double-sided copying or multiple copying, and retransmitting the recording sheet S to the transfer position Q3.

At the upper right side of the first paper feed tray T1, a manual feed tray 21 is provided. The sheets conveyed from the manual feed tray 21 by the paper feed rollers R6 and R7 and the respective sheets sent out from the respective paper feed trays T1 to T5 pass through the first sheet conveyance path 22 and are transferred to the transfer position Q.
It is to be transported to 3. First sheet transport path 2
2 is the first feed sensor SN
1 and the sheet registration sensor SNy. At the end of the first sheet conveying path 22, the transfer position Q3
A registration gate 23 and a registration roll 24 for temporarily stopping the conveyed sheet S and then carrying the sheet S to the transfer position Q3 are disposed on the upstream side in the sheet conveyance direction. The transfer device 19 arranged at the transfer position Q3 transfers the toner image on the surface of the image carrier 16 to the sheet S passing through the transfer position Q3. After the toner remaining on the surface of the image carrier 16 having passed through the transfer position Q3 is collected by the cleaner unit 20, the surface of the image carrier 16 is recharged with the charger 17 again.
Is charged uniformly.

The sheet S to which the toner image has been transferred at the transfer position Q3 is conveyed to the fixing position Q4 through the conveyance belt 26 of the second sheet conveyance path 25 connected to the sheet discharge tray TR. At the fixing position Q4, a pair of fixing rolls 27 and 2 including a heating roll 27 and a pressure roll 28 are provided.
A fixing device F having a fixing position Q4
Is configured to fix the unfixed toner image on the sheet S passing through the sheet S by heating and pressing. The fixing roll 27
A fixing heater 27h is built therein. In addition,
The surface temperature of the heating roll 27 is detected by a fixing temperature sensor SNt, and a fixing device discharge sensor SNf is disposed immediately after the fixing device F. A discharge roller 29 for discharging sheets to a sheet discharge tray TR is provided downstream of the fixing position Q4 in the second sheet transport path 25.
Is provided.

In the second sheet conveying path 25, a switching gate 31 is disposed upstream of the discharge roller 29.
The switching gate 31 is used when switching the transport direction of the sheet S on the second sheet transport path 25 to the direction of the sheet circulation path 32 or the sheet discharge tray TR. The sheet circulation path 32 is connected to a sheet reversing path 33 and the intermediate tray T0 via a switching gate. The switching gate 34 directs the sheet S of the sheet circulation path 32 to the sheet reversal path 33 when performing double-sided copying,
In the case of the multiple copy, the copy is made to go directly to the intermediate tray T0. The sheet-shaped and comb-shaped mylar gate 36 provided in the sheet reversing path 33 allows the sheet S to move downward by elastic deformation when the sheet S passing therethrough is conveyed downward. When the sheet S that has passed through the switch 36 is switched back and conveyed upward, the sheet S is guided in the direction of the intermediate tray T0. Sheet S once stored in intermediate tray T0
Are transported again from the intermediate tray T0 to the transfer position Q3 by the first sheet transport path 22.

In FIGS. 2 and 3, a developing device D arranged opposite to the image carrier 16 in the developing region Q2 contains a two-component developer composed of a negatively charged toner and a positively charged magnetic carrier. And a developing container 41 to be used. As described above, in the field of image quality improvement, in digital images, it is important to faithfully develop each pixel of the formed electrostatic latent image so that toner having the smallest possible diameter and uniform particle size can be uniformly obtained. It needs to be developed. Therefore,
In the first embodiment, the central particle size of the toner is 6.5 μm.
m, a two-component developer having a center particle diameter of the carrier of 35 μm.

The developing container 41 includes a developing roll accommodating section 42 for accommodating the developing roll R0 and the developing roll accommodating section 4
2 has a first developer pool 43 which is a first developer stirring area adjacent to the second developer pool and a second developer pool 44 which is a second developer stirring area adjacent to the first developer pool 43. I have. As shown in FIG. 6, between the first developer reservoir 43 and the second developer reservoir 44, partition walls 45 are provided at portions other than both ends thereof, and the first developer reservoir 43 is provided. The 43 and the second developer reservoir 44 are connected at connection portions E at both ends in the front-rear direction (X-axis direction). In FIG. 6, a first transport member R1 is disposed in the first developer reservoir 43, and a second transport member R2 is disposed in the second developer reservoir 44.

On the upper surface of the second developer reservoir 44, a developer supply port 48 is formed. In order to prevent the new developer supplied from the developer supply port 48 from being supplied and discharged immediately, a developer retaining section 50 for discharging the developer is disposed upstream of the developer supply port 48 in the developer transport direction. Have been. The developer reservoir 50 is a region of the second developer reservoir 44 shown in FIG. 6 and a region partitioned by the partition wall 45 from the first developer reservoir 43. (Excluding region). The region is a region in which the flow of the developer is limited in a certain direction by being partitioned by the partition wall 45 from the first developer reservoir 43 in which the surface height of the developer fluctuates due to the rotation of the developing roll R0, In addition, this is a region where the upper surface position of the developer is stable. The developer reservoir 50 includes a bottom surface 51a, an upper surface 51b, a side wall 51c parallel to a side wall of the developer reservoir 44, and the developer reservoir 4.
4. An outwardly protruding wall 51 having an upstream end wall 51d and a downstream end wall 51e disposed downstream of the developer to be conveyed.
Is formed. A developer outlet 52 is formed in the downstream end wall 51e at a portion near the developer reservoir 44. From the elements indicated by the reference numerals 42 to 52,
The developing container 41 (42 to 52) according to the first embodiment is configured.

The developer discharged from the developer discharge port 52 is collected in a developer collection container 54 through a developer discharge path 53. In FIG. 6, as the first and second transport members R1 and R2, conventionally known transport members having a transport screw mounted around a rotation axis are used, and the rear ends (-X Driven gears G1 and G2 meshing with each other are fixed to the side ends). The gear G1 of the first transport member R1 meshes with a gear G0 mounted on the rear end (-X side end) of the shaft of the developing roll R0. When a rotational force is transmitted to the gear G0 by a rotation driving device (not shown) and the gear G0 rotates, the gears G1 and G2 also rotate in opposite directions. Then, as shown in FIG. 6, the first and second developer reservoirs 43 and 4 are rotated by the first and second transport members R1 and R2 which rotate integrally with the gears G1 and G2.
The developer circulates in the area 4.

2 and 3, the developing roll R0
Is provided with a developing sleeve R0b outside the magnet roll R0a. The magnet roll R0a is provided with a pickup magnetic pole N1 for attracting the developer to the developing sleeve R0b, a trimming magnetic pole S1 located near the developer carrying amount regulating member 55 and contributing to regulating performance, and a carrying magnetic pole N2 for carrying the developer. ,
It is composed of a developing magnetic pole S2 for moving the toner onto the image carrier 16 and developing it into a toner image, and a pick-off magnetic pole N3 for peeling off the attached developer from the developing sleeve R0b.
With the rotation of the developing sleeve R0b of the developing roll R0,
The developer in the first developer pool 43 adheres to the surface of the developing sleeve R0b of the developing roll R0 by the magnetic poles N1 and S1 of the magnet roll R0a and is transported to the developing position Q2. . As shown in FIGS. 2 and 3, a developer transport amount regulating member 55 for regulating the layer thickness of the developer on the developing roll R0 is disposed in the developing roll accommodating portion.

The developing roller R0 is opposed to the developing roller R0 on the upstream side in the rotation direction of the developer conveying amount regulating member 55.
A plate-shaped rectifying member 56 is provided at a position where the rectifying member 56 can come into contact with the developer attached thereon. The rectifying member 56 is made of a rigid non-magnetic material (for example, stainless steel), and is disposed in the longitudinal direction of the developing
A developer guide 56a (see FIG. 7) extending obliquely and upward in the short side direction is formed on the upper surface at the position of the upstream / downstream connection portion of the stirring member R2. Further, as shown in FIG. 6, the rectifying member 56 is connected to the second developer reservoir 44 in the second direction.
It is shaped to extend above the transport member R2. Therefore, although the rectifying member 56 is arranged in the longitudinal direction of the developing container 41, the rectifying member 56 is
Excess developer is not returned to the downstream end of the second transport member R2 at the end (connecting portion E) at which the developer is transferred by the transport members R1 and R2. This is to prevent the excess developer from being sufficiently stirred because the distance from the downstream end to the developing roll R0 is short. In the present embodiment, in order to sufficiently stir the returned surplus developer and the new developer replenished from the developer replenishment port 48, the surplus developer is provided on the downstream side of the developer replenishment port 48. Dropped on new developer.

Since the closest point between the developing roll R0 and the rectifying member 56 is between the magnetic poles N1 and S1 of the magnet roll R0b, the contact area between the developer on the developing roll R0 and the rectifying member 56 is also the magnetic pole N1, It is between S1. Since the spike of the developer between the magnetic poles N1 and S1 has a shape along the circumferential direction of the developing roll R0, the developer density becomes higher as compared with the case where the developer is arranged extremely, and the packing effect (the rectifying member 56 and the The effect of the packing pressure formed in the flow path formed from the developing roll R0) is enhanced, and the uniformity tends to be increased.

Referring to FIG. 4B, developer supply cylinder support walls 57 are arranged before and after the developer supply port 48. As shown in FIG. 4A, the developer supply cylinder support walls 57, 5
A developer supply cylinder 58 is bonded to 7. An auger rotation shaft 59 and an auger rotation shaft 59 are provided in the developer supply cylinder 58.
A developer conveying auger 61 mounted around is rotatably arranged. A gear G is provided at one end of the auger rotating shaft 59.
3 is fixed and connected to a drive motor (not shown).

At one end of the developer supply cylinder 58, a developer storage container 62 is formed.
The high-concentration two-component developer (hereinafter, referred to as "high-concentration developer") supplied from the replenishing cylinder 62a on the upper surface is stored. From the developer storage container 62 to the developer supply cylinder 58
The high-concentration developer carried into the developer carrier auger 6
1 and is supplied to the second developer reservoir 44 from the developer supply port 48. The replenishment of the high-concentration developer is performed by a toner concentration sensor SNv (FIGS.
This is performed when the toner concentration Tb in the container detected by the above-described method is equal to or lower than the reference value Tbo. The replenishment of the high-density developer is also performed when the developed toner image density detected by the toner image density sensor SNd (see FIG. 1) is equal to or lower than a reference value.

(Operation of the First Embodiment) In the first embodiment for the developing device of the present invention having the above-described configuration, the image carrier 16 is
The surface is uniformly charged to a negative polarity by the charging device 17. Next, exposure is performed by ROS, and an electrostatic latent image is formed on the surface of the image carrier 16. The first and second transport members R1 and R2 accommodated in the first and second developer reservoirs 43 and 44 in the developing container 41 of the developing device D rotate in directions opposite to each other, and a developer supply port is provided. The high-concentration developer supplied from 48 is stirred and conveyed, and is made into a homogeneous two-component developer triboelectrically charged by the mixing action of the toner and the carrier. The uniformly mixed two-component developer is deposited in a layer on the peripheral surface of the developing sleeve R0b by the magnetic force of the magnet roll R0a. The developer on the surface of the developing roll R0 is formed in a uniform layer by the developer transport amount regulating member 55. At this time, the developer is conveyed by the rotation of the developing sleeve R0b.
Since the packing pressure increases in the flow path formed from 0, the developer density and the toner concentration are made uniform and the toner is charged. The uniform developer layer formed on the surface of the developing roll R0 is transported to the developing area Q2 by the rotational force of the developing sleeve R0b,
A developing bias in which the AC component is superimposed on the component is applied, and only the toner is moved toward the electrostatic latent image on the image carrier 16 to form a toner image.

On the other hand, the surplus developer that has not passed through the developer transport amount regulating member 55 moves between the developer transport amount regulating member 55 and the rectifying member 56 by receiving the rotational force of the developing sleeve R0b. When the developer roll R0 is released from the magnetic binding force of the developing roll R0, it flows on the upper surface of the rectifying member 56 and returns to the second transport member R2 of the second developer pool 44. At this time, although the rectifying member 56 is disposed in the longitudinal direction of the developing container 41, the guide portion 56a of the rectifying member 56
Accordingly, the surplus developer is not returned to the downstream end of the second transport member R2 at the end (connecting portion E) where the developer is transferred by the two transport members R1 and R2. This is to prevent the excess developer from being sufficiently stirred because the distance from the downstream end to the developing roll R0 is short. Since the returned surplus developer falls onto the replenished toner, the mixing operation due to the vertical switching of the developer becomes larger, and the mixing performance of the toner and the carrier and the charging ability to the toner are improved more than before. can do.

In the conventional configuration, the surplus developer stays on the upstream side (back side) of the developer conveying amount regulating member 55 due to the magnetic force. This stagnation gives the developer a stress (pressure and frictional force such that the surface layer of the carrier is peeled off or the external additive of the toner is peeled off), and the amount of the developer contributing to the development is reduced. The problem of accelerating the deterioration of the developer occurs. However, since the magnetic force acting on the developer on the rectifying member 56 by the magnet roll R0a is attenuated by the rectifying member 56, the developer flows on the rectifying member 56 and returns to the second developer reservoir 44. Therefore, the amount of the developer decreases on the upstream side of the developer conveyance amount regulating member 55, so that the amount of the developer contributing to the development can be increased. A sheet S such as a recording sheet or a transparent transfer material to which the toner image is transferred is taken out from the paper feed trays T0 to T5, is conveyed, and is temporarily stopped by the registration gate 23. At the transfer position Q3 between the image carrier 16 and the transfer device 19. At the transfer position Q3, the toner image on the image carrier 16 is transferred onto the sheet S by the transfer device 19.
Then, the sheet S on which the toner image has been transferred is fixed to the fixing device F.
Is heated and fixed, and is discharged to the sheet discharge tray TR. After the transfer of the toner image, the toner remaining on the surface of the image carrier 16 is scraped off by the cleaner unit 20.

When the above-described copying operation is repeated,
The toner in the developer contained in the developing container 41 of the developing device D of FIG. 6 is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration decreases.
This change in toner density is detected by an in-container toner density sensor SNv provided in the developing container 41. When the toner concentration Tb in the container falls below an appropriate range necessary for development, the developer transport auger 5 is driven by a driving motor (not shown).
9 is driven to replenish the high-concentration developer in the developer storage container 62 from the developer supply port 48 into the developer container 41.

On the other hand, the carrier in the developer in the developing container 41 is not consumed by the developing operation, but is agitated together with the toner in the developing container 41 or the magnetic force of the magnet roller of the developing roll R0. Due to the influence and the contact with the image carrier 16 and the toner, the toner adheres to the carrier surface, and the surface is gradually contaminated and deteriorated. When the carrier deteriorates in this way, the charging performance of the developer is reduced, and a predetermined amount of charge cannot be given to the toner, and the image quality is reduced. In FIG. 6, the developer circulating in the first and second developer reservoirs 43 and 44 is retained in a developer retaining portion 50 formed by an outwardly projecting wall 51 formed on a side wall of the developer reservoir 44. . The developer that is retained in the developer retaining section 50 and that is close to the developer reservoir 44 moves while being dragged by the developer being conveyed through the developer reservoir. This developer is supplied to a developer outlet 52 formed in a portion of the downstream end wall 51e near the developer reservoir 44.
Is discharged to the developer discharge path 53. The discharged developer is collected in the developer collection container 54.

The developer storage section 50 and the developer discharge port 52
Are disposed in the second developer reservoir 44 and the partition wall 4.
5 is disposed in a portion partitioned from the developer reservoir 43. The developer discharge port 52 is located at the position of the developing roll R
This is a position where the upper surface height of the developer is not changed by the influence of 0, and the developer height is stable. In addition, the position of the developer outlet 52 is a position where the developer is constantly conveyed by the second conveying member R2. Therefore, the developer retained in the developer retaining section 50 is the second developer.
When the developer is constantly dragged and moved by the transporting member R2, the developer is discharged from the developer discharging port 52.

(Embodiment 2) FIG. 8 is an enlarged explanatory view of a main part of Embodiment 2 of the developing device of the present invention. In the second embodiment, elements corresponding to the elements of the first embodiment are denoted by the same reference numerals, and redundant detailed description will be omitted. In the second embodiment, a rectifying member 63 having a shape obtained by bending a flat plate is used instead of the rectifying member 56 having the flat plate shape in the first embodiment. That is, the developer guide portions 63a are provided at both front and rear ends.
The rectifying member 63 has a second angle based on the inclination angle of the developing roll R0.
The inclination angle on the side of the developer agitating region 44 is formed more gently. In the second embodiment, the two-component developer stored in the developer storage container 64 is supplied to the developer supply port 48 of the developing container 41 by the auger rotating shaft 66 and the developer transport auger 67 supported by the auger rotating shaft 66. It is configured to be replenished. The auger rotating shaft 66 has a gear G at the outer end thereof.
4 is connected to a drive motor (not shown)
The rotation of the motor is transmitted via the gear G4.
With the configuration described above, the second embodiment has the same operation as the first embodiment. Further, by changing the inclination angle of the rectifying member 63 on the second transport member R2 side, the second transport member R2
Can be adjusted.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention can be applied to analog copying machines, printers, facsimile machines, and the like, in addition to digital copying machines. (H02) The present invention is not limited to a trickle-type developing device that always supplies a new toner while replacing a deteriorated carrier with a new carrier, but also a developing device that always supplies only new toner without replacing the carrier. It is also possible to apply to the device. (H03) In each of the above embodiments, instead of forming the developer storage container with one developer storage container containing a high-concentration developer having a high toner concentration, two storage containers, a toner storage container and a carrier storage container, are used. It is possible to separately control the supply of the toner and the carrier. Further, the developer storage container can be composed of two containers, a container storing a high-concentration developer having a high toner concentration and a toner storage container. (H04) In the invention, it is possible to arrange a paddle between the developing roll and the first transport member. (H05) The developer stagnation section and the developer discharge path of the present invention can be formed integrally with the outer wall of the container of the developing container, or can be formed easily with respect to the outer wall of the container. (H06) The developing device of the present invention is applicable to a rotary type and a tandem type color image forming apparatus. (H07) In the embodiment of the present invention, the rectifying member may be changed to a member having a triangular cross section instead of a plate-shaped member.

[0050]

The above-described developing device of the present invention has the following effects. (E01) It is possible to provide a developing device which can sufficiently mix a carrier and a toner having a small particle diameter and sufficiently charge even a small developing device.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus including a developing device according to a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of the developing device shown in FIG. 1 and is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged explanatory view of the developing device shown in FIG. 1 and is a sectional view taken along line III-III of FIG.

FIG. 4 is an explanatory view of the developing container shown in FIG. 2;
FIG. 4A is a perspective view of a developing device, and FIG. 4B is a perspective view of a state in which a developer supply member is removed from the developing device.

5 is a sectional perspective view of a main part of a developer discharging portion of the developing container shown in FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 2;

FIG. 7 is a perspective view of a rectifying member of the developing container.

FIG. 8 is an enlarged explanatory view of a main part of a developing device according to a second embodiment of the present invention.

[Explanation of symbols]

E: Both ends in the axial direction, (N1, S1): Between the poles, (N1, S1,
N2, S2, N3) ... magnetic pole, Q2 ... development area, R0 ... development roll, R0a ... magnet roll, R0b ... development sleeve, R1 ...
1st conveying member, R2 2nd conveying member 41 ... developing container, 42 ... developing roll accommodating part, 43 ... 1st
Developer stirring area, 44: second developer stirring area, 45: partition wall, 48: developer supply port, 55: developer conveyance amount regulating member, (56; 63): rectifying member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kei Hirata 2274 Hongo, Fuji Xerox Co., Ltd., Ebina-shi, Kanagawa Prefecture Inventor Yoshiharu Suga 2274 Hongo, Ebina City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. A developing device having the following requirements: (A01) a cylindrical developing sleeve for conveying a two-component developer composed of a toner and a carrier to a developing area; and a developing sleeve disposed inside the developing sleeve. A developing roll provided with a magnet roll having a plurality of magnetic poles on a cylindrical surface, (A0
2) a developing roll accommodating portion for accommodating the developing roll, a developer carrying amount regulating member for regulating an amount of the two-component developer adhered to the surface of the developing roll and being carried to the developing region; A first developer stirring region extending in the axial direction of the developing roll adjacent to the portion, and a portion disposed adjacent to the first developer stirring region on the opposite side to the developing roll and excluding both ends in the axial direction. The partition is partitioned from the first developer stirring region by the partition wall, and both ends in the axial direction are connected to the first developer stirring region and formed between the partition wall and a container outer wall extending along the partition wall. A second developer agitating area, a developer container having a developer supply port for replenishing a new developer inside the container, and (A03) the excess developer generated upstream of the developer transport amount regulating member by the second developer. Return to the stirring area A rectifying member that is arranged opposite to the surface of the developing roll and that comes into contact with the surface of the developing roll and that comes into contact with a two-component developer that is attached to and conveyed to the surface of the developing roll; (A04) the first developer stirring; (A05) a first transport member that is disposed in the area and agitates while transporting the two-component developer in the axial direction of the developing roll; (A06) The above-mentioned carrier having an average particle diameter of not less than 20 μm and not more than 50 μm. 2. The developing device according to claim 1, wherein the developer supply port is provided with:
The developing container provided upstream of a position where the developer falls from the rectifying member to the second developer stirring area. 3. A developing device having the following requirements: (B01) a cylindrical developing sleeve for conveying a two-component developer comprising a toner and a carrier to a developing area; and a cylindrical developing sleeve disposed inside the developing sleeve. Developing roll provided with a magnet roll having a plurality of magnetic poles on a cylindrical surface,
2) a developing roll accommodating portion for accommodating the developing roll, a developer carrying amount regulating member for regulating an amount of the two-component developer adhered to the surface of the developing roll and being carried to the developing region; A first developer stirring region extending in the axial direction of the developing roll adjacent to the portion, and a portion disposed adjacent to the first developer stirring region on the opposite side to the developing roll and excluding both ends in the axial direction. The partition is partitioned from the first developer stirring region by the partition wall, and both ends in the axial direction are connected to the first developer stirring region and formed between the partition wall and a container outer wall extending along the partition wall. A second developer stirring area, a developer container having a developer supply port for replenishing a new developer inside the container, and (B03) removing excess developer generated upstream of the developer transport amount regulating member with the second developer. Return to the stirring area A rectifying member which is arranged opposite to the surface of the developing roll and which comes into contact with the surface of the developing roll and which comes into contact with the two-component developer conveyed while being adhered to the surface of the developing roll; (B04) the first developer stirring; (B05) a first transporting member disposed in the region and agitating while transporting the two-component developer in the axial direction of the developing roll; and (B05) a two-component developer disposed in the second developer agitating region and mixing the two-component developer with the first transporting member. (B06) The carrier having a flowability of 30 sec / 50 g or more as measured by JISZ2502. 4. The developing device according to claim 3, wherein: (B07) said developer supply port is provided with:
The developing container provided upstream of a position where the developer falls from the rectifying member to the second developer stirring area.