JPH0753083Y2 - 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.
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 conventional developing device A for a 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.

Further, it is an object of the present invention to provide a developing device capable of reducing the load torque applied to the drive unit of the developing roller.

<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. 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 rotary drive means E for the spindle 20.

An arc-shaped developer bristling plate 24 is arranged between the developing roller 22 and the photoconductor, and a doctor 35 for regulating the amount of the developer 2 attached to the bristling plate 24 is provided. A developer scraping end 24a for scraping off the developer 2 adhering to the magnet body 21 and moving it to the spike forming plate 24 is formed at the end of the stand forming plate 24. A non-magnetic separator a1 (press scraper) for separating a part of the developer 2 from the magnet body 21 is arranged on the opposite side of the magnet body 21 in the rotation direction of the magnet body 24a.
The a1 has a shape in which the separated developer 2 can move toward the spike forming plate 24.

<Operation> In the above means for solving the problem, the magnet body 21, which has been conventionally fixed, is rotated. Then, the developer 2 which is erected along the magnetic lines of force due to the magnetic forces of the magnets N and S moves with the rotation of the magnet body 21.

Most of the developer 2 adhered to the developing roller 22 that is weakly restrained by the magnetic force is sprung up by the separator a1.
2b is once separated from the magnet body 21. Since the separating body a1 and the scraping end 24a are close to each other, the spikes 2b separated from the magnet body 21 move toward the spike forming plate 24 as they are.

Further, the developer 2 which is not separated from the magnet body 21 by the separator a1, that is, the separator a1 and the magnet body 21.
The developer 2 that has entered the gap is scraped off by the scraping end 24 a by the rotation of the magnet body 21, and moves onto the spikelet forming plate 24. This is because the distance a from the outer peripheral surface of the magnet body 21 to the scraping end 24a is the separation body from the outer peripheral surface of the magnet body 21.
This is because it is set smaller than the distance b to a1.

In this way, a part of the developer 2 is separated from the magnet body 21 and moved onto the spike forming plate 24. That is, the developer 2 attached to the magnet body 21 is separated into two parts by the separating body a1 and the scraping end 24a, and is moved onto the spike forming plate 24, so that the developer 2 is removed at the scraping end 24a. The load torque of the magnet body 21 when scraping is reduced,
The life of the drive unit (drive motor 31) can be extended.

Further, when the developer 2 moves to 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 spike height of the developer 2 is regulated by the doctor 35,
It is conveyed on the spike 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.

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

<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 thereof, and a rotary drive means E for the support shaft 20 is provided.

An arc-shaped developer spike forming plate 24 is arranged between the developing roller 22 and the photoconductor 23, and scrapes off the developer 2 attached to the developing roller 22 at the end of the spike forming plate 24. A developer scraping end 24a is formed for moving on the bristling plate 24, and the developer scraping end 24a is provided on the opposite side of the developer scraping end 24a in the rotation direction of the magnet body 21 and close to the scraping end 24a. A small-diameter columnar non-magnetic separator for separating a part from the magnet body 21.
a1 (press scraper) is installed, and the magnet body
Distance b from the outer peripheral surface of 21 to the separator a1 (for example, 0.5 mm)
Is set to be larger than the distance a (for example, 0.05 to 0.1 mm) from the outer peripheral surface of the magnet body 21 to the scraping end 24a.

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 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. ,
It is formed from an arc-shaped spike forming portion 24c that connects the scraping end 24a and the sink end 24b.

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.
The distance a is extremely close to the peripheral surface of 22. At the scraping end 24a of the spike forming plate 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. Further, the front and rear end portions of the bristles forming plate 24 are fixed to the front and rear plates 26, 27 of the developing tank 1.

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 spike forming 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 developing tank 1.

As shown in FIG. 1, the separating body a1 is arranged slightly below the scraping end 24a, the separating body a1 is formed to be longer than the magnet body 21, and both ends of the separating body a1 are connected to the developing unit. It is fixed to the front and rear plates 26, 27 of the 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.

When the developing roller 22 rotates in the clockwise direction B, the part of the developer 2 attached to the developing roller 22 that is weakly restrained by the magnetic force is once separated from the magnet body 21 by the separating body a1 in a spiked state. To be done. Since the separating body a1 and the scraping end 24a are close to each other, the developer 2 separated from the magnet body 21 directly moves toward the spike forming section 24c as shown by the arrow C1.

Further, the developer 2 which is not separated from the magnet body 21 by the separator a1, that is, the separator a1 and the magnet body 21.
The developer 2 that has entered is scraped off by the scraping end 24a by the rotation of the magnet body 21, as shown by the arrow C2, and moves toward the spike forming portion 24c. This is because the distance a from the outer peripheral surface of the magnet body 21 to the scraping end 24a is
This is because the distance b is set to be smaller than the distance b from the outer peripheral surface of the separator a1.

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 developer 2
Reaches the spike forming portion 24c, 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.

The developer 2 that has not transferred to the photoconductor 23 on the bristling 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.

Thus, the developer 2 is separated from the magnet body 21 by the separator a1 immediately before the developer 2 is scraped by the scraping end 24a. That is, since the developer 2 adhering to the magnet body 21 is separated by the separating body a1 and the scraping end 24a in two steps, the load on the magnet body 21 when scraping the developer 2 at the scraping end 24a. The torque is reduced, and the life of the drive unit (drive motor 31) of the magnet body 21 can be extended.

The state of conveyance of the developer 2 in 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 adhered is large, the magnetic forces of the magnets N and S are less likely to reach the entire developer on the spike forming portion, so that the developer 2 is moved by the movement of the magnets N and S as shown in FIG. Although the direction of the tips of the developer changes, 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 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.
Then, in the second embodiment, even if the number of magnets N and S is reduced by half, by increasing the rotation speed of the developing roller 22, a good spike of the developer 2 can be formed. 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 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 sewn and an image of high quality 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.

Also, a plurality of separators a1 may be arranged side by side in the circumferential direction of the magnet body 21.

<Effect of the Invention> As is apparent from the above description, according to the present invention, a part of the developer is separated from the magnet body by the separator just before the developer is scraped by the scraping end, and the spikes are erected. Since the developer is moved to the forming plate, the load on the magnet body is reduced when the developer is scraped by the scraping end and moved to the spike forming plate, and the life of the drive unit of the magnet body can be extended.

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, in the past, a bearing structure for supporting the support shafts of the magnet body and the sleeve was required, but according to the present invention, when the bearing structure of only the magnet body is provided and 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 a main part of a developing device of a copying machine showing a first embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional plan view of the same, FIG. 4 is a vertical sectional view of a single developing roller, and FIG. 5 is a vertical sectional front view of a developing roller in a use state when a large amount of developer adheres to the developing roller. Similarly, FIG. 7 is a vertical sectional front view of a developing roller in a developing device of a copying machine showing a second embodiment of the present invention when a small amount of developer adheres to the developing roller. 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 entire vertical sectional front view of the developing device of the copying machine showing the conventional example, and FIG.
FIG. 11 is a front view of the same developing roller alone, and FIG. 12 is a vertical sectional front view of the same developing roller. 1: developing tank, a1: separator, 2: developer, 20: spindle, 21: magnet body, 22: developing roller, 23: photoconductor, 24: developer spike formation plate, 24a: scraping end, 24b: sink end, A: developing device, 24c:
Heading formation part, 25: support rod, B: direction of rotation of magnet body (clockwise direction), 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 comprises a support shaft rotatably supported by the developing tank, and a magnet body fixed to the support shaft and having a plurality of magnets on its outer peripheral surface. And 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, and the amount of the developer attached to the spike forming plate. Is provided, a developer scraping end for scraping the developer adhering to the magnet body and moving it to the spike forming plate is formed at the end of the spike forming plate. A separator for separating a part of the developer from the magnet body is disposed on the opposite side of the developer scraping end in the direction of rotation of the magnet body, and a separator is provided for separating a part of the developer from the magnet body. It was shaped so that it could move in the direction of the spike formation plate. A developing device of a copying machine, characterized and.