JPH06130801A - Doctor for developing device and method for working the same - Google Patents

Abstract

PURPOSE:To reduce a stress imparted to a developing agent and to prolong its life by forming the top end part in the upstream side in the rotational direction of a doctor regulating the napping of the developer on a developing roller into a circular-arc shape. CONSTITUTION:In the developing device provided with the freely rotatable developing roller 16 on a developing tank 12 and the doctor 31 regulating the napping of the developer of the developing roller 16, when a plate is punched out and the top end part is grounded, the doctor 31 is diagonally grounded so that the upstream side in the rotational direction of the top end part is separated from the developing roller 16 from the upstream side in the rotational direction of the top end part toward the downstream side, remaining the circular-arc shape formed at the time of punching. Therefore, when the doctor 31 regulates the napping of the developer on the developing roller 16, the stress imparted to the developer is reduced by the circular-arc shape formed on the top end part of the doctor 31 and the life of the developer can be prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a doctor for regulating the amount of developer on a developing roller in a developing device using a one-component or two-component developer such as an electrophotographic copying machine and a laser printer.

[0002]

2. Description of the Related Art In a conventional developing device, a developing roller in a developing tank magnetically adsorbs the developer, and the developer stands on the surface of the developing roller. Is regulated. Then, the developer regulated by the doctor is conveyed by the rotation of the developing roller and is brought into sliding contact with the photoconductor to develop the electrostatic latent image.

Since this doctor is formed by punching out a flat plate, as shown in FIG.
In the punching, arc-shaped sags, burrs, etc. are generated due to the gap between the molds 3 and 4.

However, in order to make the amount of the developer on the developing roller uniform, the straightness of the doctor was important.

Therefore, as shown in FIG.
The tip portion 2 of No. 2 was polished with the line BB 'to improve the straightness of the doctor.

[0006]

However, in the conventional method for polishing the doctor 1, since the doctor 1 is used perpendicularly to the side surface of the doctor 1, the doctor 1 loses the arc formed during punching, and the developing roller is not formed. The front end portion 2 on the upstream side in the rotation direction is an edge. Therefore, the stress on the developer is increased, the life of the developer is shortened, and the image quality is not uniform. In recent image forming apparatuses, high image quality is required, and the developing conditions that determine the image quality are becoming more severe. Improving the dimensional accuracy of the doctor that regulates the amount of developer on the developing roller. Was also an important issue.

In view of the above, an object of the present invention is to provide a developing apparatus doctor capable of improving image quality without stressing the developing agent.

[0008]

In the means for solving the problems according to claims 1 and 2 of the present invention, the developing roller 16 is rotatably provided in the developing tank 12 as shown in FIGS. In the developing device provided with the doctor 31 for controlling the spike of the agent, when the doctor 31 punches a flat plate and polishes the tip 33, the upstream side of the tip 33 in the rotational direction is an arc shape formed during punching. Leaving 34
The tip portion 33 is obliquely polished so as to be separated from the developing roller 16 from the upstream side to the downstream side in the rotation direction.

[0009]

In the above means for solving the problems, when the doctor 31 regulates the spike of the developer on the developing roller 16, the arcuate shape 34 formed at the tip portion 33 of the doctor 31 causes
Stress applied to the developer is reduced and the life of the developer is extended.

[0010]

FIG. 1 is a sectional view showing a developing device according to an embodiment of the present invention, FIG. 2 is a perspective view of a first stirring roller, FIG. 3 is a perspective view of a second stirring roller, and FIG. 4 is a perspective view of an agitator. FIG. 5 shows a doctor, (A) is a plan view thereof, (B) is a side view thereof, FIG. 6 is an enlarged view of the front end portion of the doctor, and FIG. 7 is a sectional view of a carrier.

As shown in FIG. 1, the developing device of the present embodiment comprises a developing tank 12 opposed to the photoconductor 11 and a toner replenishing tank 13 arranged above the developing tank 12.

A toner replenishing port 1 is provided above the developing tank 12.
4 and an opening / closing lid 15 for opening / closing the toner supply port 14.

A developing roller 16 is disposed in the developing tank 12 in the vicinity of the photoconductor 11, and the first and second agitating rollers 17, 1 are directed from the developing roller 16 toward the toner replenishing port 14.
8 are sequentially arranged, and the first and second stirring rollers 17 and 18 are arranged.
A conveyance magnet roller 19 is disposed above the space between
An agitator 20 is arranged below the toner supply port 14.

A toner replenishing roller 21 is rotatably installed in the toner replenishing tank 13, and the toner replenishing port 14 is provided.
Supply toner from.

The developing roller 16 is externally fitted to a support shaft 22 rotatably supported in the developing tank 12 and fixed to the developing tank 12, and a magnet body 23 is rotatably fitted to the magnet body 23. And a sleeve 24, which is rotationally driven counterclockwise by a motor.

The first stirring roller 17 is, as shown in FIG.
A roller shaft 17a rotatably supported by the developing tank 12,
A large number of fins 25 are provided so as to be perpendicular to the roller shaft 17a.

The second stirring roller 18 is, as shown in FIG.
A roller shaft 18a rotatably supported by the developing tank 12,
A large number of elliptical fins 26 are attached to the roller shaft 18a so as to be inclined.

As shown in FIG. 4, the agitator 20 is composed of a shaft 20a rotatably supported by the developing tank 12 and two fins 27 projecting in the tangential direction of the shaft 20a.

The transport magnet roller 19 is fitted on a support shaft 28 rotatably supported on the developing tank 12 and fixed to the developing tank 12, and a magnet body 29 is rotatably fitted on the magnet body 29. And a sleeve 30.

The rollers 16 to 20 are rotationally driven by a motor in conjunction with the direction of the arrow shown in FIG.

Above the developing roller 16, a doctor 31 for controlling the height of the spikes of the developer on the developing roller 16 is provided.
Are arranged.

As shown in FIG. 5, the doctor 31 is a flat plate punched by press working, and is screwed to the developing tank 12 through a hole 32. Then, as shown in FIG. 6, the tip end portion 33 of the developing roller 16 which controls the rising of the developer leaves an arcuate shape 34 formed during punching and leaves the developing roller 1 from the upstream side to the downstream side in the rotational direction.
The shape is inclined so as to be separated from 6.

In FIG. 1, reference numeral 35 is a first flow plate, 36 is a second flow plate, and 37 is a toner concentration sensor.

In the above structure, the toner replenished from the toner replenishing tank 13 through the toner replenishing port 14 is crushed by the agitator 20 and sent to the second stirring roller 18.

Then, the developer and the toner are agitated by the second agitating roller 18, the toner is rubbed against the carrier in the developer and charged to the opposite polarity to the electrostatic latent image, and a part of the toner is charged to the first stream. It is pumped up by the transport magnet roller 19 along the drain plate 35, and along the second sink plate 36.
Returned in the direction of. The remaining developer is the first stirring roller 1.
Flow toward 7 and stir further.

Then, the developer sent to the developing roller 16 magnetically adheres to the sleeve 24 to form a brush and a magnetic brush is formed, and the sleeve 24 is rotated to be conveyed to the photosensitive member 11 side. It

On the way, the developer is smoothly moved without receiving stress from the doctor 31, and is conveyed to the photoconductor 11 while the height of the spikes of the magnetic brush is regulated, and the electrostatic latent image on the photoconductor 11 is transferred. Development.

At this time, the amount of the developer on the developing roller 16 is determined by adjusting the clearance between the doctor 31 and the developing roller 16. Normally, this clearance is 0.5 to 2.0 mm, and the adjustment error is ± 0.025 to 0.
05 mm is common. However, this value is becoming severer year by year as the copy image quality becomes higher.

By the way, in order to control the spike of the developer, the clearance between the doctor 31 and the developing roller 16 must be adjusted, and the straightness in the longitudinal direction of the doctor tip 33 is important. In order to improve the straightness, the tip portion 33 is polished.

That is, when the flat plate is punched by a press, an arcuate shape 34 is generated due to the gap between the molds as shown in FIG. Conventionally, this arc shape has almost disappeared. Therefore, since the carrier 38 in the developer is composed of the Fe core material 39 and the Si coating material 40 as shown in FIG. 7, the coating material 40 is peeled off by the stress of the doctor 31 or the like, and the doctor 31 The life of the developer changes depending on the shape. Therefore, the arc shape 34
The presence or absence of the developer greatly affects the life of the developer.

Therefore, in the present embodiment, when the tip portion 33 of the doctor 31 is polished, polishing is performed up to the line AA 'shown in FIG. 6 so that the arcuate shape 34 is left as much as possible.

Then, the peeling test of the coating material 40 on the surface of the carrier 38 by aging with respect to the shape of the tip of the doctor 31 was conducted, and the result is shown in FIG. In the figure,
A is a conventional doctor, B is the doctor of this embodiment, and C is an unpolished doctor after punching.

The peeling of the coating material 40 on the carrier 38 is analyzed by a fluorescent X-ray analyzer. In a fluorescent X-ray analyzer, when a substance is irradiated with X-rays, part of the X-rays absorbed by the substance is emitted as fluorescent X-rays having a specific energy (wavelength) depending on the type of each element. The fluorescent X-rays are dispersed by a dispersive crystal, and the wavelength and intensity of the X-rays are measured to find out the type and amount of the element contained in the substance.

Then, the developer after 20,000 copies, 50,000 copies, and 100,000 copies are sampled by aging, the toner is removed by blow-off of the developer, and only the carrier 38 is left, and the fluorescent X-ray analysis is performed. Elemental analysis of the carrier 38 is performed by the apparatus. Then, the amounts of Fe and Si of the core material 39 and the coating material 40 of the carrier 38 are measured, respectively, and the amount of the coating material 40 with respect to the core material 39 (Si / F
Calculate the ratio of e).

As shown in FIG. 8, almost the same good results were obtained for B and C, but for A, the peeling of the coating material 40 of the carrier 38 was large.

In this way, the tip portion 33 of the doctor 31 is
However, by polishing with leaving the arc 34 formed during punching shown in FIG. 6, the stress applied to the developer is reduced and the peeling of the coating material 40 of the carrier 38 is reduced, so that the life of the developer is extended. be able to.

Further, in the conventional case, the straightness of the doctor is 0.05 mm, while the lengthwise dimension of the doctor is 467 mm.
However, in this embodiment, since the doctor straightness is improved to 0.03 mm and the doctor accuracy can be improved, it is possible to set severe developing conditions and obtain a high quality copy. be able to.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

[0039]

As is apparent from the above description, according to the inventions of claims 1 and 2, since the tip portion of the doctor is polished while leaving the arc formed during punching, the stress applied to the developer is reduced. However, the life of the developer can be extended.

Further, since the straightness of the doctor in the longitudinal direction is improved and the dimensional accuracy of the doctor is improved, the amount of the developer on the developing roller can be regulated uniformly. Therefore, there is an excellent effect that a severe development condition can be set and a high quality copy can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a developing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a first stirring roller.

FIG. 3 is a perspective view of a second stirring roller.

FIG. 4 is a perspective view of an agitator.

5A is a plan view of the doctor, and FIG. 5B is a side view of the doctor.

FIG. 6 is an enlarged view of the tip of the doctor.

FIG. 7 is a sectional view of a carrier.

FIG. 8 is a diagram showing a peeling ratio of a carrier coating material due to aging with respect to a doctor shape.

FIG. 9 is an enlarged view of the tip of the doctor when punching.

FIG. 10 is an enlarged view of the tip of a conventional doctor.

[Explanation of symbols]

 11 Photoreceptor 12 Developing Tank 16 Developing Roller 31 Doctor 33 Tip Part 34 Arc 38 Carrier 39 Core Material 40 Coating Material

Claims (2)

[Claims] 1. A developing device in which a developing roller is rotatably provided in a developing tank, and a doctor is provided for restricting the rising of the developer on the developing roller. A doctor for a developing device, wherein the is formed in an arc shape. 2. The doctor according to claim 1, wherein when the flat plate is punched and the tip portion is polished, the upstream side in the rotational direction of the tip portion remains the arc shape formed during punching, and the upstream side in the rotational direction of the tip portion. The method for processing a doctor of a developing device is characterized in that the polishing is performed obliquely so as to be separated from the developing roller toward the downstream side.