JPH073410Y2 - Copier developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention transfers a developer to an electrostatic latent image formed on a photoconductor by exposure of an exposure lamp in an electrostatic transfer copying machine, for example. And a developing device for.

<Prior Art> FIGS. 9 to 12 show a developing device of a conventional copying machine.
The developing device A includes a developing roller 1, a stirring roller 3 for stirring the developer 2 (toner and carrier), a developing roller 6 for transferring the developer 2 to the photoconductor 4, and a photoconductor 4. Doctor 7 that regulates the amount of developer 2 that adheres
And a toner concentration sensor 8 for detecting the concentration of the developer 2 in which the developer 2 has been consumed by the developing operation and the toner 2a has decreased.

Then, as shown in FIGS. 10 and 12, the developing roller 6 is composed of three to five pole ferrite magnets 9 and a cylindrical magnet supporting rod 10 for supporting the magnets 9.
A magnet body 11, a magnet support shaft 11a for supporting the magnet body 11, a sleeve 12 loosely fitted to the outside of the magnet body 11, and a sleeve support shaft 12a for supporting the sleeve 12. And the magnet body 1
Reference numeral 1 is fixed to the developing tank 1 through a magnet support shaft 11a.

In this developing device A, the sleeve 12 is rotated, and the amount of the developer 2 attached to the sleeve 12 by the magnetic force of the magnet 9 is limited by the doctor 7 for developing.

Reference numeral 13 in FIG. 10 is a bearing for rotatably supporting the sleeve 12 in the developing tank 1. Reference numeral 14 is a rotation driving means for the sleeve 12, 15 is a drive motor thereof, and 16 is a gear for transmitting the driving force of the drive motor 15 to the sleeve support shaft 12a. Further, in FIG. 9, reference numeral 17 denotes a toner replenishing roller arranged above the developing tank 1, which is rotated by a density shortage signal from the toner density sensor 8 so that the toner 2a is transferred from the toner box 18 to the developing tank 1. To supply.

<Problems to be Solved by the Invention> In the developing device A of the conventional copying machine, as shown in FIGS. 9 and 12, the sleeve 12 is expensive, so that the entire covering area of the magnet body 11 is covered. Becomes larger,
There is a problem when the cost of the entire developing device becomes high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device for a copying machine, which can reduce costs.

Furthermore, it aims at providing the developing device which can prevent the deterioration of a developing agent.

<Means for Solving Problems> In the means for solving problems according to the present invention, as shown in the sectional views of FIGS. 1 and 2, a developing roller 22 is provided in the developing tank 1, and the developing roller 22 is the developing tank. Spindle 20 rotatably supported by 1
And a plurality of magnets N, S fixed on the support shaft 20 on the outer peripheral surface.
And a magnet body 21 having a.

A rotation driving means E of the support shaft 22 is provided, and an arc-shaped developer spike forming plate is provided between the developing roller 22 and the photoconductor 23.
24 is provided, and a separating means F for separating the developed image agent 2 from the magnet body 21 is provided.

The separating means F is arranged so as to face the magnet body 21 on the rotation direction side of the magnet body 21 with respect to the spike forming plate 24, and a separation assisting magnetic piece fa for concentrating the magnetic fields of the magnets N and S. And a developer separating piece fa which comes into contact with the magnet body 21 on the rotation direction side of the magnet body 21 with respect to the separation assisting magnetic piece fa.

<Operation> In the above means for solving the problem, the magnet body 21, which has been conventionally fixed, is rotated. Then, due to the magnetic force of the magnets N and S, the developer 2 which is erected along the magnetic lines also moves with the rotation of the magnet body 21. Then, when the developer 2 moves to the end of the arc-shaped spike forming plate 24 provided in place of the conventional sleeve, the spike forming plate 24
Magnets N and S that are scraped by the scraping end 24a of the
By the magnetic force of, the ears form on the ears forming plate 24.
Then, the photoconductor 23 and the developer 2 come into contact with each other, the developer 2 is transferred to the electrostatic latent image formed on the photoconductor 23, and development is performed.

Here, the magnetic piece fa for concentrating the magnetic fields of the magnets N, S causes the magnetic field N, S as shown in C of FIG.
And a magnetic piece fa are formed linearly. Panning plate
The developed developer 2 that has not transferred to the photoconductor 23 on 24 is
When the magnet body 21 is rotated to reach the vicinity of the separating means F, the developer 2 is densely gathered along the linear magnetic field, and as the magnet body 21 rotates, the developer 2 is separated from the surface of the magnet body 21 by a separating piece fb. Easily separated. Then, the developer 2 separated from the magnet body 21 is guided by the separation piece fb, and the arrow D
As described above, it is smoothly fed to the stirring roller 3.

In this way, the developer 2 is easily separated from the magnet body 21, and the separated developer 2 is sent to the stirring roller 3.
When the toner is agitated by the agitating roller 3 and adheres to the magnet body 21 again, the operation is repeated, so that the deterioration of the developer 2 can be prevented.

Further, by forming the spike formation plate 24 in an arc shape,
The cost of the developing roller 22, which has been a large weight in the cost of the developing device A, can be greatly reduced, and the cost of the entire developing device can be reduced.

<Embodiment> An embodiment of a developing device of a copying machine according to the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention is an enlarged vertical sectional front view of a main part of FIG. 1, an entire vertical sectional front view of FIG. 2, a cross sectional plan view of FIG. 3, and a vertical sectional front view of a developing roller of FIG.
Description will be given based on the vertical sectional front views of the usage state shown in FIGS. 5 and 6.

As shown in the figure, in the developing device A according to the first embodiment of the present invention, a developing roller 22 is provided in the developing tank 1, and the developing roller 22 is a support shaft 20 rotatably supported by the developing tank 1. And a magnet body 21 fixed to the support shaft 20 and having a plurality of magnets N, S on the outer peripheral surface.

A rotation driving means E for the support shaft 20 is provided, and an arc-shaped developer spike forming plate is provided between the developing roller 22 and the photoconductor 23.
24 is provided, and a developer scraping end 24a for scraping the developer 2 adhering to the developing roller 22 and moving it to the spike forming plate is formed at the end of the spike forming plate 24, and Separation means F for separating the used developer 2 from the magnet body 21 is provided, and the separation means F is arranged in the rotational direction of the magnet body 21 rather than the spike forming plate 24.
It is composed of a separation assisting magnetic piece fa for concentrating the N and S magnetic fields, and a developer separating piece fb which comes into contact with the magnet body 21 in the vicinity of the separation assisting magnetic piece fa.

As shown in FIG. 4, the magnet body 21 is composed of a cylindrical support rod 25 and the magnets N and S in which different poles are alternately embedded in the outer periphery of the support rod 25 at 45 ° intervals.

The developing roller 22 is disposed near the opening 1a formed on the side of the photoconductor 23 of the developing tank 1. The front and rear ends 20a, 20b of the support shaft 20 of the developing roller 22 are rotatably supported by the front and rear plates 26, 27 of the developing tank 1 via bearings 28, 29.

The developing roller 22 is rotated in the clockwise direction B in FIG. As shown in FIG. 3, the drive means E includes a drive motor 31, a motor-side gear 32 that fits on a rotary shaft 31a of the drive motor 31, and a shaft-side gear 33 that meshes with the motor-side gear 32. The shaft side gear 33 is externally fitted and fixed to the rear end portion 20b of the support shaft 20.

The ears forming plate 24 is made of a non-magnetic conductor (for example, made of aluminum or stainless steel) and has a length substantially equal to that of the opening 1a.

As shown in FIG. 2, the spike forming plate 24 has the developer scraping end 24a at the end opposite to the rotating direction of the developing roller 22 and the developer flowing end at the rotating side end of the developing roller 22. 24b
And the scraping end 24a and the sinking end 24b are formed by a continuous arc-shaped spike forming portion 24c.

The spike forming portion 24c is a circular arc concentric with the magnet body 21, and the magnet N, from the peripheral surface of the developing roller 22,
The magnets N and S are arranged so as to be separated by a reference distance L at which the magnetic force of S acts, and have a thickness t at which the magnetic forces of the magnets N and S favorably act.

The scraping end 24a and the sinking end 24b are formed at an acute angle as shown in FIG. 2, and the peripheral surface of the developing roller 22 (the developer 2
Of the developing roller.
Very close to the circumference of 22. And the spike formation plate
At the scraping end 24a of 24, the developer 2 attached to the developing roller 22 can be easily scraped off, and at the sinking end 24b, the developer 2 can be easily swept to the stirring roller side. The front and rear end portions of the bristling plate 24 are the front and rear plates 2 of the developing tank 1.
It is fixed at 6,27.

The separation piece fb and the magnetic piece fa are both formed in a plate shape, and are arranged on the outer peripheral portion of the magnet body 21 on the rotation direction side of the magnet body 21 with respect to the ear stand forming portion 24c of the ear stand forming plate 24. .

The separation piece fb and the magnetic piece fa are the front and rear plates 26, 27 of the developing tank 1.
It is supported and fixed to. As shown in FIG. 2, the separation piece fb
Are arranged on the magnet body rotation direction side with respect to the magnetic piece fa.

The separating piece fb is an acute-angle separating portion f1 at the tip that contacts the outer peripheral surface of the magnet body 21, and a developing roller 2 formed on the stirring roller side of the separating portion f1 and stirring the developed developer 2 separated by the separating portion f1. 3 and a feeding portion f2 for feeding the sheet. The concept of contact between the separating piece fb and the magnet body 21 includes a gap of up to about 0.1 mm in consideration of the driving torque up of the developing roller 22 and the friction of the developing roller contact portion of the separating piece fb.

The magnetic piece fa has a rectangular constant cross section.

Reference numeral 35 in FIGS. 1 and 2 is a doctor for previously regulating the amount of the developer 2 transferred to the photoconductor 23. And the doctor
35 is disposed on the photoconductor side of the scraping edge 24a of the spike forming plate 24 and on the rotation direction side of the developing roller 22.
Is formed on the lower surface of the open end. The other structure is the same as the conventional structure shown in FIG.

Explaining the operation next, when the drive motor 31 is driven,
The support shaft 20 rotates via the gears 32 and 33. Then, the magnet body 21 fixed to the support shaft 20 rotates. At this time, the developer 2 that has been stirred and frictionally charged by the rotation of the stirring roller 3 in advance has already gathered on the developing roller due to the magnetic force of the magnets N and S along the line of magnetic force, resulting in the arched spikes 2b. I'm running.

Then, when the developing roller 22 rotates in the clockwise direction B, the developer 2 attached to the developing roller 22 is scraped by the scraping end 24a of the spike forming plate 24, and the magnetic force of the magnets N and S causes the spike to be formed. Hold.

Further, when the developer 2 is conveyed in the clockwise direction B by the rotation of the developing roller 22, the doctor 35 regulates the amount of the developer 2 adhering to the spike forming portion 24c. And the photoconductor 23
And the developer 2 come into contact with each other, the developer 2 is transferred to the electrostatic latent image formed on the photoconductor 23, and development is performed. In addition, a bias voltage is applied to the spike forming plate 24.

Further, the developed developer 2 that has not transferred to the photoconductor 23 on the bristling portion 24c is conveyed to the agitating roller 3 side by the rotation of the developing roller 22 and again with the developer 2 in the developing tank 1. Be stirred. At this time, the magnetic field is linearly formed between the magnets N and S and the magnetic piece fa by the magnetic piece fa that concentrates the magnetic fields of the magnets N and S, as shown by C in FIG.
The arch-shaped spike 2b of the developer 2 is released.

Then, the developer 2 is densely packed along the linear magnetic field, and the developed developer 2 attached to the magnet body 21 is separated into pieces.
It is easily separated at the separating portion f1 of fb. Then, the developer 2 separated from the magnet body 21 is smoothly sent to the agitating roller 3 as indicated by an arrow D along the feeding portion f2 of the separating piece fb.

Further, the state of conveyance of the developer 2 at the spike forming unit 24c changes depending on the amount of the developer 2 attached to the developing roller 22. That is, when the amount of the developer 2 attached is large, the magnetic forces of the magnets N and S are less likely to reach the entire developer on the spike forming portion,
As shown in FIG. 5, the direction of the tips of the developer 2 is changed by the movement of the magnets N and S, but the movement of the developer 2 on the spike forming plate is small.

Further, when the amount of the developer 2 adhered is less than the proper amount, the magnetic force of the magnets N, S easily reaches the entire developer, so that the developer 2 is moved in the moving direction by the movement of the magnets N, S as shown in FIG. Move in the same direction on the spike forming plate.

For example, if the diameter of the developing roller 22 is 25 mm, the magnetic force of the magnets N and S is 700 gauss, and the thickness of the spike forming plate 24 is 1.0 mm, the amount of developer adhered to the spike forming plate 24 is 1 to 2 mm. It will be an appropriate amount.

As described above, the developed developer 2 attached to the magnet body 21 is easily separated at the separation portion f1 of the separation piece fb, and the developer 2 separated from the magnet body 21 is distributed along the feeding portion f2 of the separation piece fb. Then, the toner is smoothly sent to the stirring roller 3 as shown by the arrow D and is stirred again by the stirring roller 3, so that the deterioration of the developer 2 can be prevented.

Further, since the sleeve, the flange, etc. can be eliminated from the conventional developing roller and good development can be performed, the developing roller, which has been a large weight in the cost of the developing device A, can be greatly reduced in cost. The cost of the developing device as a whole can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the developing device A according to the second embodiment of the present invention, the magnets N and S of the developing roller 22 are arranged on the outer periphery of the supporting rod 25 at 90 ° intervals as shown in FIG. The other structure is similar to that of the first embodiment.

In the above structure, the magnets N, S are compared with the first embodiment.
The number can be reduced by half, and the cost can be further reduced.
In the second embodiment, even if the number of magnets N and S is halved, the developer 2 can form a good spike by increasing the rotation speed of the developing roller 22. Other functions and effects are similar to those of the first embodiment.

Next, a third embodiment of the present invention will be described based on the vertical sectional front view of FIG.

In the developing device A in the third embodiment of the present invention, the spike forming plate 24 is formed as shown in FIG. That is, the thickness of the spike forming plate 24 becomes maximum in the central portion of the spike forming plate 24, the maximum thickness t is equal to that of the spike forming plate 24 in the first embodiment, and the cross-sectional area continuously changes. The thickness is gradually reduced toward the scraping end 24a and the sink end 24b. The other structure is similar to that of the first embodiment.

In the above-described structure, the maximum thickness t of the ears forming plate 24 is set to a thickness that does not adversely affect the ears of the developer 2, so that the ears of the developer 2 are satisfactorily raised and a high-quality image is obtained. Other functions and effects are similar to those of the first embodiment.

It should be noted that 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.

For example, the shape of the spike forming plate 24 is not limited to the above embodiment, and may be formed in a polygonal shape close to an arc shape.

Further, the shape of the separation assisting magnetic piece fa is not limited to the above-mentioned embodiment, and may be formed in a columnar cross section.

In the case where the rotating direction of the magnet body 21 is opposite to that of the above embodiment, the separating means F is of course provided on the rotating side of the magnet body 21 (under the spike forming plate 24) in accordance with this. is there.

<Effect of the Invention> As is apparent from the above description, according to the present invention, the developed developer that has not transferred to the photoconductor on the spike forming plate is
When it comes to the vicinity of the separating means by the rotation of the magnet body, it becomes dense along the magnetic field between the magnet and the magnetic piece,
The separation piece easily separates it from the surface of the magnet body, agitates it with a stirring roller, and repeats the operation when it adheres to the magnet body again, so that the deterioration of the developer can be prevented. Moreover, since the developed developer can be easily separated from the surface of the magnet body, the load on the magnet body can be reduced and the life of the drive unit of the magnet body can be extended.

In addition, by rotating the conventionally fixed magnet body and providing an arcuate spike forming plate instead of the cylindrical sleeve, the material cost for the sleeve can be reduced.
It is possible to greatly reduce the cost of the developing roller, which has been a large weight in the cost of the developing apparatus, so that the cost of the entire developing apparatus can be reduced. Further, conventionally, a bearing structure for supporting the spindle of each of the magnet body and the sleeve was required, but the bearing structure of only the magnet body is required, and the structure of the entire developing device can be simplified.

[Brief description of drawings]

FIG. 1 is an enlarged vertical front view of essential parts of a developing device of a copying machine showing a first embodiment of the present invention, FIG. 2 is an overall vertical front view of the same, FIG. 3 is a cross-sectional plan view of the same, and FIG. 4 is the same. FIG. 5 is a longitudinal sectional front view of the developing roller alone, and FIG. 5 is a longitudinal sectional front view of the developing roller when the developing roller adheres to a large amount.
Similarly, FIG. 7 is a vertical sectional front view of a use state when a small amount of developer adheres to the developing roller, and FIG. 7 is a vertical sectional front view of a developing roller of a developing device of a copying machine showing a second embodiment of the present invention. FIG. 8 is a vertical sectional front view of a developing device of a copying machine showing a third embodiment of the present invention, FIG. 9 is an entire vertical sectional front view of a developing device of a copying machine showing a conventional example, and FIG. First
FIG. 11 is a front view of a single developing roller, and FIG. 12 is a vertical sectional front view of the same developing roller. 1: developer tank, 2: developer, 20: spindle, 21: magnet body, 22:
Developing roller, 23: photoconductor, 24: developer spike formation plate, 24
a: scraping end, 24b: sinking end, A: developing device, 24c: spike forming part, 25: support rod, B: rotating direction of magnet body (clockwise direction), F: separating means, fa: separating auxiliary magnetism Piece, fb: developer separation piece, N, S: magnet.

Claims (1)

[Scope of utility model registration request] 1. A developing roller is provided in a developing tank, and the developing roller has a support shaft rotatably supported by the developing tank, and a magnet body having a plurality of magnets on an outer peripheral surface fixed to the support shaft. In order to separate the developed developer from the magnet body, a rotation driving means for the spindle is provided, and an arc-shaped developer spike forming plate is arranged between the developing roller and the photoconductor. Separation means are provided,
The separating means includes a separation assisting magnetic piece arranged to face the magnet body on the rotation direction side of the magnet body with respect to the spike forming plate and for concentrating the magnetic field of the magnet, and the separation assisting magnetic piece. A developing device for a copying machine, which is also composed of a developer separating piece that comes into contact with the magnet body on the rotation direction side of the magnet body.