JPH07109529B2 - Copier developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> 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 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.
And a magnet support 11a that supports the magnet body 11, a sleeve 12 that is loosely fitted to the outside of the magnet body 11, and a sleeve support shaft 12a that supports 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 disposed above the developing tank 1, which is rotated by the density insufficient signal from the toner density sensor 8 to transfer the toner 2a from the toner box 18 to the developing tank 1. Supply.

<Problems to be Solved by the Invention> In the developing device A of the conventional copying machine, the sleeve 12 is expensive as shown in FIGS. 9 and 12, and therefore the covering area is covered by covering the whole negnet body 11. 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 the cost.

Another object of the present invention is to provide a developing device capable of improving the image quality.

<Means for Solving Problems> In the means for solving the 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. 1. A support shaft 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 rotary drive means E for the spindle 20.

An arc-shaped developer spike forming plate 24 made of a non-magnetic material is disposed between the magnet body 21 and the photoconductor 23, and the developer 2 is formed on the magnet forming 21 side of the spike forming plate 24. Magnetic powder 24d for making the developing pressure uniform is dispersed and arranged.

<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. At this time, since the magnetic powder 24d is dispersed in the spike forming plate 24, the magnetic fields of the magnets N and S are dispersed.
Then, by dispersing the magnetic field, the magnet body 21
Since the developing pressure of the developer 2 caused by the difference in the magnetic force in the radial direction is uniformly corrected, uneven development is prevented,
A good image can be obtained.

Further, by 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 occupying a large waist in the cost of the developing device A, and to reduce the cost of the entire developing device. .

<Embodiment> An embodiment of the developing device of the copying machine of 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 single longitudinal 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 drawing, 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 thereof, and a rotary drive means E for the support shaft 20 is provided.

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 scraped off at the end of the spike forming plate 24. Then, a developer scraping end 24a for moving it onto the spike forming plate 24 is formed, and magnetic powder 24d for making the developing pressure of the developer 2 uniform is dispersed on the spike forming plate 24. It was done.

As shown in FIG. 4, the magnet body 21 is composed of an arcuate 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 bristles forming plate 24 is formed of an outer (photoconductor side) non-magnetic conductive portion 24A (for example, made of aluminum or stainless steel) and a resin body 24B fixed inside the non-magnetic conductive portion 24A (magnet body side). , The magnetic powder 24d is a resin body 24
Sprinkled inside B.

The spike forming plate 24 is formed to have a length substantially equal to that of the opening 1a.

As shown in FIG. 2, the spike forming plate 24 has the developing scraping end 24a at the opposite end of the developing roller 22 in the rotational direction, and the developer flowing end 24b at the rotational end 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. 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.

Reference numeral 35 in FIG. 2 is a doctor for previously regulating the amount of the developer 2 transferred to the photoconductor 23. And the doctor 35
Is arranged on the photoconductor side of the scraping edge 24a of the bristling plate 24 and on the rotation direction side of the developing roller 22, and is formed on the lower surface of the opening end of the developed image 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 which 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 force lines, and the spikes 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 while being attracted by the magnetic force of the magnets N, S. 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. At this time, since the magnetic powder 24d is dispersed in the resin body 24B, the magnetic fields of the magnets N and S are dispersed. Then, by dispersing the magnetic field, the developing pressure of the developer 2 caused by the difference in the magnetic force of the magnet body 21 in the radial direction is uniformly corrected,
The developer 2 uniformly contacts the development point of the photoconductor 23, uneven development is prevented, and a good image is obtained. Further, when the rotation speed of the magnet body 21 is increased, the developing pressure of the developer 2 becomes more uniform, and a very good image can be obtained. In addition, a bias voltage is applied to the spike forming plate 24.

Further, the developer 2 which 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. It

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, 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 the same as that of the one 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. ,
It is formed thinner as it approaches 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.

Alternatively, the spike forming plate 24 may be formed only from the non-magnetic conductive portion 24A, and the magnetic powder 24d may be dispersed and fixed to the back surface of the non-magnetic conductive portion 24A.

<Effects of the Invention> As is apparent from the above description, according to the present invention, since the magnetic powder is dispersed in the spike forming plate, the magnetic field of the magnet is dispersed, and the magnetic field is dispersed, so that the magnet is dispersed. Since the developing pressure of the developer caused by the difference in magnetic force in the radial direction of the body is uniformly corrected, uneven development is prevented and a good image is obtained.

In addition, by rotating the magnet body that was conventionally fixed and providing the arcuate spike forming plate instead of the cylindrical sleeve, the large cost of the developing roller, which until now has been a large weight in the cost of the developing device. It is possible to reduce the cost of the developing device as a whole.

Further, conventionally, a bearing structure for supporting the support shafts of the magnet body and the sleeve was required, but according to the present invention, a bearing structure of only the magnet body is required, and when the structure of the entire developing device is simplified, It has an excellent effect.

[Brief description of drawings]

FIG. 1 is an enlarged vertical sectional 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 longitudinal sectional 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 single 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, 24d: magnetic powder, 25: support rod, B: rotating direction of magnet body (clockwise direction), N, S: magnet .

Claims (1)

[Claims] 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. And a rotation driving means for the spindle is provided, and an arc-shaped developer spike forming plate made of a non-magnetic material is disposed between the magnet body and the photoconductor. 2. A developing device for a copying machine, wherein magnetic powder for equalizing a developing pressure of a developer is dispersedly disposed on the magnet side of the above.