JP3499513B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION[0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer and the like.
And a developing device of the image forming apparatus.[0002] 2. Description of the Related Art A toner and a carrier are provided on an electrostatic latent image carrier.
Developing by supplying developer consisting of components
In the developing device, the toner and the carrier in the developing housing
Agitating the toner to mix the toner and carrier and
Developer agitating means for performing triboelectric charging and transporting in a predetermined direction
It has been known. In recent years, space-saving image forming devices
Demands, especially a quadruple tandem with multiple developing units.
Color copiers and color printers
The downsizing of the developing device is essential.[0003] Disclosed the requirements for this developing device
JP-A-10-142942 exists as prior art
Developer supply means for supplying a developer to the electrostatic latent image carrier
And a developer provided near the developer supply means.
First stirring and conveying means for stirring and conveying in the direction of
The developer is provided below the stirring means and the developer is moved in a direction opposite to the first direction.
Second stirring and conveying means for stirring and conveying the developer in the second direction
And provided coaxially with the developing supply means,
The second stirring and conveying hand is driven in accordance with the driving of the feeding means.
Sending the developer conveyed by the step to the first stirring means
Feed means, the feed means comprising a first rotary three
In the second rotating sleeve, which is different from the
It has a magnetic pole for attracting the image agent, and is provided with a second stirring and conveying means.
The developer conveyed by the second rotating sleeve
By the rotation, the feeding means for sending to the first stirring and conveying means
Some have been disclosed.[0004] However, the above publication
In the developing device disclosed in Japanese Patent Laid-Open Publication No.
It is not enough in terms of miniaturization of the device. Especially the second stirring on the lower side
The developer is pumped from the conveying means to the upper first stirring / conveying means.
A magnet provided in a second rotating sleeve for feeding
The magnetic strength of the poles has a large contribution to the developer transport.
This has a significant effect on image quality. The present invention
Are a first stirring and conveying means and a second stirring and conveying means
In the developing device of the vertical stirring and conveying means provided with
From the second stirring and conveying means to the upper first stirring and conveying means
Pumping developer without stagnation and oversupply
More stable and high-quality developed images
And[0005] Means and Actions for Solving the Problems The above problems are solved.
In the present invention, in order to determine the
A developing sleeve that carries the image material and rotates;
A first agitator that is provided near the stirrer and agitates and transports the developer.
A stirring and conveying means, and
Downstream end of the developer in the conveying direction of the first stirring and conveying means
Receiving the developer, stirring the developer and transporting the developer.
Second stirring means for supplying to the sleeve, and the first stirring
Provided at a substantially central portion in the height direction between the first stirring means and the second stirring means.
Develop at the downstream portion in the developer conveyance direction by the second stirring means
Developing agent receiving and supplying to the first stirring means
In a developing device having a lifting means, a developer
The step is a rotating body having an even number of magnetic poles provided in the circumferential direction.
And the magnetic force A (10-4 T) of each pole of the developer pumping means.
The relation of the peripheral speed B (mm / sec) is 72000 ≦ A ·
B ≦ 300000The developer pumping means
When the magnetic force A (10 @ -4 T) is 500≤A≤1200Is
And features. Also, the developer pumping means has a magnetic pole.
Rotating body and there is no sleeve around it
In addition, the length in the width direction can be reduced.[0006] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.
explain. The developing device according to the present embodiment is
An example of a developing device using a photographic method
However, since the overall configuration is already well known, the present invention
Diagram of the developing device used in the Carlson process
Charging means, exposure means, cleaning means, etc. are not shown.
No.[0007] FIG. 1 shows a developing device according to an embodiment of the present invention.
FIG. 5 is a view of the developing device as viewed from above.
You. 2 is a sectional view taken along line AA in FIG. 1, and FIG.
FIG. 2 is a sectional view taken along line BB in FIG. The developing device 30 is a developing device.
A housing 144 is provided.
A leave 146 is provided. Development sleeve is aluminum etc.
And a magnet material 150 is disposed inside.
ing. Next, the developer stirring and conveying means is the first stirring and conveying means.
68 and provided immediately below the first stirring and conveying means 68
And a second stirring and conveying means 70. Stirring carrier
The step has spiral blades formed in the axial direction of the rotating shaft.
And transports the developer in a predetermined direction while stirring. In particular
The second stirring / conveying means is a developing sleeve in the developing housing.
And is located opposite to the developing sleeve.
Developer over the entire area of the developing sleeve
To supply the developer.[0008] Next, the developer pumping means 82 will be described.
I do. The developer pumping means 82 is as shown in FIG.
The vertical direction of the first stirring and conveying means and the second stirring and conveying means
At a substantially central portion, a first stirring and conveying means and a second stirring and conveying means
It is located to the right of the step. Developer pumping roller 86
Is made of a magnetic material, and N poles and S poles are alternately arranged in the circumferential direction.
And 4 poles each, 8 poles in total in the axial direction
Have been. The length of the pumping roller is preferably 15 to 50 mm.
Or 20 to 30 mm. Features of the present invention
However, the developer is agitated on the conveying means and the developing sleeve.
Developer stress caused by stagnation or shortage
First of all, in order to prevent the
The relationship between the magnetic force A of the pole and the peripheral speed B is 72000 ≦ AB
It is set to become. Is this relational expression and image
And the relationship between toner scattering outside the machine and image density.
It is shown in Table 1. The experiment was a tandem color printer.
Using A4 size PPC paper at 26 sheets / min
Check by printing up to 1000 sheets each time
Was. The developer used at this time was polyester as the binder.
Used, contains colorant and other additives,
8.5 μm diameter toner particles and central particles as magnetic material
A carrier using ferrite particles with a diameter of 60 μm
The toner concentration was adjusted at 4% by weight. Also on the pump
The length of the roller was 27 mm.[0009] [Table 1] [0010]In the table, “Developer blowing” refers to the current
The end of the image sleeve overflows from the weak magnetic part to the outside of the developing device.
State. In this experiment, the developer
Due to the shortage of pumping
The developer remains on the developer pumping means side of the
Where the magnetic force is weak at the end of the developer pumping means side of the leave
Some of them overflowed the developer. "Image fogging"
Insufficiently charged toner may not adhere to non-image areas.
"Toner scattering" means that the toner is
It refers to the state of adhering to a transmission path or the like. In this experiment, the developer
The toner is not sufficiently agitated due to the accumulation of
Some had legs. As for the image density,
The image density itself does not matter because it is maintained as
The feeling that the part is raised against the non-image part becomes stronger and total
Image quality is not good. More than necessary
Use of toner for
Is not economical for the user.
You.[0011] "Toner agglomeration" is caused by stagnant developer.
If the stress on the image agent increases, the toner flow
In this case, the mobility is deteriorated and the toner is hardened.
From the results shown in Table 1, the magnetic force A and the peripheral velocity B of each pole were
Pumping stays due to setting as above
The first stirring and conveying means and the developing sleeve
No fogging due to stagnation of developer at
It can be understood that a high-quality image is obtained. In addition, development three
Blow out the toner from the toner cartridge and in the first stirring and conveying means.
For toner aggregation, the value is up to 69000 ≦ AB
Can be reduced, but the above-mentioned image fogging and toner scattering
Therefore, it is impossible as a whole evaluation. Feature 2 of the present invention
First, the magnetic force A of each pole of the developer pumping means and
Set the relationship of speed B so that 300,000 ≧ AB
That you are doing. This relation and the turnip in the image
The relationship between toner scattering outside the machine and image density.
It is shown in FIG. The experiment was performed as described above.[0012] [Table 2] [0013]In this experiment, the pumping amount was large,
The developer does not stay in the second stirring and conveying means,
No blowing of the developer occurs. Image fogging and toner flying
For the dispersion, the amount of the developer in the second stirring and conveying means is reduced.
Decreasing the amount promotes deterioration of the developer. to this
Image fogging and photo-to-
Gnar scattering occurred. Image density is developed on the developing sleeve
It cannot be maintained due to insufficient supply of the agent. Also Tona
-For coagulation, the pumped developer is first agitated and transported.
The toner stays in the means, increasing the stress on the toner,
State. Therefore, the magnetic force A and the peripheral speed B of each pole are set to 300
Excessive pumping by setting 000 ≧ AB
That is, the first stirring and conveying means and the developing
Transfer developer without running out of developer in leave
Is performed, the pumping means and the second stirring and conveying means
No aggregation of toner at
Degree can be maintained. Is it due to toner deterioration
No fogging or toner scattering is observed. These experiments
From the above, the relationship between the magnetic force A and the peripheral speed B is expressed as 72000 ≦ A · B ≦
Although it was specified as 300,000, here we focus only on magnetic force
And 400 ≤ A ≤ 1600 (10-4T)
It is. Also, it may cause deterioration of the developer during pumping.
Speed control to avoid applying excessive stress to the developer
Alternatively, it is desirable to set the magnetic force distribution. Therefore,
Do not increase the peripheral speed of the developer pumping roller, and the magnetic force is large.
Considering the condition that it does not work, the value of magnetic force A
Is preferably 500 ≦ A ≦ 1200 (10 −4 T).[0014] As described above, according to the present invention, the developer is used in the second
Developer pumping means from the downstream side in the transport direction of the stirring transport means
Pump without stagnation and oversupply,
By sending to the agitating and conveying means, fog and toner scattering
High-quality developed image with stable and stable image density
Can be obtained. Also, the developer pumping means
Rotating body with magnetic poles, no sleeve around
Therefore, the length in the width direction can be shortened.

[Brief description of the drawings] FIG. 1 is an overall view of a developing device. FIG. 2 is a sectional view taken along line AA in FIG. FIG. 3 is a sectional view taken along line BB in FIG. 1; [Explanation of symbols] 28: electrostatic latent image carrier 30: Developing device 68: First stirring and conveying means 70: Second stirring and conveying means 82: developer pumping means 86: Developer pumping roller 144: developing housing 146: developing sleeve 150: Magnet material

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-142942 (JP, A) JP-A-7-64400 (JP, A) JP-A 7-121031 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 15/08 110 G03G 15/08 507

Claims (1)

(57) Claims: (1) A developing sleeve which faces a latent electrostatic image bearing member and rotates while carrying a developer, and a developer provided near the developing sleeve for stirring and transporting the developer. First stirring and conveying means,
A second developer is provided below the first stirring and conveying means, receives the developer at a downstream end in the conveying direction of the developer by the first stirring and conveying means, stirs and conveys the developer, and supplies the developer to the developing sleeve. A stirrer, and a developer provided at a substantially central portion in the height direction of the first stirrer and the second stirrer, and receiving the developer at a downstream portion in a developer conveying direction by the second stirrer; In a developing apparatus having a developer pumping means for supplying to the stirring means, the developer pumping means is a rotating body having an even number of magnetic poles provided in a circumferential direction, and a magnetic force A (10-) of each pole of the developer pumping means. 4T) and the peripheral speed B (mm / sec)
72000 ≦ A · B ≦ 300000 , and developer pumping
The magnetic force A (10-4T) of each pole of the lifting means is 500≤A≤
A developing device in the image forming apparatus, wherein the developing device is 1200 .