JPH06105373B2 - 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, for example, an electrostatic transfer copying machine. And a developing device for.

<Prior Art> A conventional developing device for a copying machine is shown in FIGS.
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 toner 2a that has consumed the developer 2 due to the developing operation has decreased.
And have.

As shown in FIGS. 9 and 11, 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. 9 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. 8, reference numeral 17 denotes a toner replenishing roller disposed above the developing tank 1, which is rotated by a density shortage signal from the toner density sensor 8 to cause the toner 2a from the toner box 18 to the developing tank 1. To supply.

<Problems to be Solved by the Invention> In the conventional developing device A for a copying machine, as shown in FIGS. 8 and 11, 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.

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

<Means for Solving Problems> The means for solving the problems according to the present invention is, as shown in the sectional views of FIGS. 1 and 2, a developing device provided in the vicinity of the opening 1a facing the photoconductor 23 of the developing tank 1. The roller 22 is composed of a support shaft 20 rotatably supported by the developing tank 1 and a magnet body 21 having a plurality of magnets N, S on the outer peripheral surface fixed to the support shaft 20. An arc-shaped developer spike forming plate 24, which is provided from the rotation driving means E of 20 and has a length substantially equal to the opening 1a and is made of a non-magnetic conductor, is provided between the developing roller 22 and the photoconductor 23. Then, the developer 2 adhering to the developing roller 22 is scraped off at the end portion of the spike forming plate 24 to remove the spike forming plate 24.
A developer scraping end 24a for moving upward is formed, and a doctor 35 for regulating the amount of the developer 2 adhering to the spike forming plate 24 is located downstream of the scraping end 24a in the developer moving direction. It is distributed.

<Operation> In the above problem solving means, the magnet body 21, which has been conventionally fixed, is rotated. Then, magnet N, S
Due to the magnetic force of the developer 2, the developer 2 which is erected along the line of magnetic force 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 are erected on the ears forming plate 24,
The height of the spikes of the developer 2 is regulated by the doctor 35, and the developer 2 is conveyed to the spike forming plate 24. Then, the photoconductor 23 and the developer 2 come into contact with each other in the opening 1a, the developer 2 is transferred to the electrostatic latent image formed on the photoconductor 23, and development is performed.

By thus forming the spike forming plate 24 in an arc shape, it is possible to greatly reduce the cost of the developing roller 22, which has been a large weight in the cost of the developing device A, and to reduce the cost of the entire developing device. You can

<Examples> Examples of a developing device of a copying machine according to the present invention will be described below with reference to the drawings. First, the first embodiment of the present invention is shown in FIG. 1 as a whole vertical sectional front view, in FIG. 2 as a cross sectional plan view, in FIG. 3 as a single longitudinal sectional front view of a developing roller, and as shown in FIG. 4 and FIG. A description will be given based on the front view.

As shown in the drawing, the developing device A in the first embodiment of the present invention is provided with the developing roller 22 of 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 having the support shaft 20 fitted and fixed therein and having a plurality of magnets N, S on the outer peripheral surface thereof, and a rotation drive means E for the support shaft 20 is provided.

Further, an arc-shaped developer spike forming plate 24 is disposed between the developing roller 22 and the photoconductor 23, and the developer 2 attached to the developing roller 22 is scratched at the end of the spike forming plate 24. A developer scraping end 24a for picking up and moving it onto the spike forming plate 24.
Are formed.

As shown in FIG. 3, 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 clockwise by the driving means E in FIG. As shown in FIG. 2, 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. 1, the spike forming plate 24 has a developer scraping end 24a at the opposite end in the rotation direction of the developing roller 22 and a developer flowing end 24b at the end in the rotation direction of the developing roller 22. ,
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. 1, 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 is easily scraped off, and at the sinking end 24b, the developer 2 is 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.

Reference numeral 35 in FIG. 1 is a doctor for previously regulating the amount of the developer 2 transferred to the photoconductor 23. And the doctor 35
Are arranged on the photoconductor side and on the rotation direction side of the developing roller 22 with respect to the spikes and the scraping end 24a of the forming plate 24, and are formed on the lower surface of the opening end of the developing tank 1. 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 magnetic lines, and the ears 2b
It is said.

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 developer 2 that has not transferred to the photoconductor 23 on the spike forming portion 24c is conveyed to the stirring roller 3 side by the rotation of the developing roller 22 and is stirred again with the developer 2 in the developing tank 1. .

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. 4, 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 2 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, since the sleeve, the flange and the like 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 significantly reduced in cost. Therefore, the cost of the entire developing device can be reduced.

Next, a second embodiment of the present invention will be described based on a front view of a single longitudinal section of the developing roller shown in 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 peripheral portion 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.
Since the number of is reduced to half, 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.

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.

<Effects of the Invention> As is apparent from the above description, according to the present invention, the magnet body is rotated instead of the conventional developing roller composed of the fixed magnet body and the rotatable cylindrical sleeve,
By providing the arc-shaped spike forming plate made of a non-magnetic conductor only in the opening facing the photoconductor, the sleeve can be eliminated while maintaining good developing performance. Therefore, it is possible to significantly reduce the cost of the developing roller, which has been a large weight in the cost of the developing apparatus, and to reduce the cost of the entire developing apparatus. Moreover, conventionally, a bearing structure for supporting the support shaft of each of the magnet body and the sleeve was required, but the bearing structure of only the magnet body is used, and the structure of the entire developing device is simplified.

In addition, the spike-forming plate has a length almost equal to that of the openings, and the amount of developer adhered is regulated by a doctor, so it is possible to prevent scattering of the developer from the openings and eliminate image unevenness. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional front view of a developing device of a copying machine showing a first embodiment of the present invention, FIG. 2 is a cross sectional plan view of the same, FIG. 3 is a vertical sectional front view of a single developing roller, and FIG. Similarly, a vertical sectional front view of a usage state when a large amount of developer adheres to the developing roller, FIG. 5 is a vertical sectional front view of a usage state when a small amount of developer adheres to the developing roller, and FIG. FIG. 7 is a vertical sectional front view of the developing roller of the developing device of the copying machine showing the second embodiment of the present invention. FIG. 7 is a vertical sectional front view of the developing device of the copying machine showing the third embodiment of the present invention. FIG. 9 is an overall vertical sectional front view of the developing device of the copying machine, FIG. 9 is a cross-sectional plan view of the same, FIG. 10 is a single front view of the same developing roller, and FIG. 11 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: direction of rotation of magnet body (clockwise direction), N, S: magnet.

Claims (1)

[Claims] 1. A developing roller is provided in the vicinity of the opening of the developing tank facing the photoconductor, and the frictionally charged developer is erected on the developing roller so that the developer comes into contact with the photoconductor. In the developing device for developing by the above, the developing roller is composed of a support shaft rotatably supported in the developing tank, and a magnet body fixed to the support shaft and having a plurality of magnets on its outer peripheral surface. A rotation driving means for the spindle is provided, and an arc-shaped developer spike forming plate made of a nonmagnetic conductor and having a length substantially equal to the opening is disposed between the developing roller and the photoconductor. A developer scraping end for scraping the developer adhering to the developing roller and moving it to the spike forming plate at the end of the rising forming plate, and the amount of the developer adhering to the spike forming plate The doctor who regulates A developing device of a copying machine is also characterized in that disposed in the developer moving direction downstream side.