JPH0365553B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus, and particularly to an improvement in a developer replenishing means in a developing device thereof.

[Prior art and its problems]

An example of a conventional developing device will be explained with reference to FIG.

An electrostatic latent image is formed on the surface of the photoreceptor 1 by a charging and exposing means (not shown), and is sent to a developing area as the photoreceptor 1 rotates. The developing device 2 is constructed by arranging a non-magnetic sleeve 4 having a magnet roll therein, a stirring roll 5, and a regulating plate 6 in a hopper 3. The developer 10 is conveyed by the rotation of the non-magnetic sleeve 4, passes through the regulation plate 6 and is regulated to a constant height, and then comes into contact with the surface of the photoreceptor 1, making the electrostatic latent image on the surface of the photoreceptor 1 visible. Let it be image 7. The developer 10 after development is further conveyed by the rotation of the non-magnetic sleeve 4 and stirred by the stirring roll 5.

If the above development process is repeated, only the toner in the developer 10 is consumed and the toner concentration gradually decreases, resulting in a decrease in image density, so it becomes necessary to replenish the toner in the developer 10. As a method for replenishing the toner, there is a method in which the toner concentration in the developer 10 is measured and the toner 9 is replenished by the toner replenishing roll 8 in accordance with the measured toner concentration. However, this method has disadvantages in that it is easily affected by humidity and requires expensive parts such as detection sensors, leading to increased costs.

Furthermore, there are some devices that replenish toner by utilizing a change in the volume of the developer due to a change in the toner concentration of the developer. In this method, the opening of the toner hopper that stores toner is placed directly on the upper surface of the developer, and as the toner concentration decreases, the developer volume decreases and the level of the upper surface of the developer also decreases. Since there is a head difference between the openings, the stored toner is supplied to the developer from the opening. When the upper surface level of the developer reaches a position where the toner popper opening is again blocked by toner replenishment, toner replenishment is stopped. However, since this method is carried out based on the level of the top surface of the developing device, there is no problem when using the developing device in a normal horizontal state. If this operation is performed, or if this opening operation is performed in an image forming apparatus whose main body can be opened across the transfer paper transport path, the upper surface level of the developer in the developing device may become uneven and the horizontal state may become uneven. It will no longer be maintained.
Therefore, there is a difference in height between the upper surface level of the developer and the opening of the toner hopper, resulting in the inconvenience that toner replenishment is performed even though the toner concentration is sufficient. Excessive supply of toner also leads to deterioration of image quality.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide an image forming apparatus that can prevent excessive toner supply and provide stable images over a long period of time.

[Key points of the invention]

In order to achieve the above object, the present invention provides an image forming apparatus comprising a developing device having a developer that develops an electrostatic latent image on an image carrier, and a replenishing means for replenishing the developing device with a replenishing developer. In the apparatus, the replenishment is performed for a predetermined image forming operation period after the completion of a moving operation in which the developing device moves from a non-image forming operation position where the image forming operation is not performed to an image forming operation position where the image forming apparatus main body performs the image forming operation. It is characterized by stopping the means.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of the vicinity of the developing section of an image forming apparatus showing an embodiment of the present invention, and shows a state in which the developing device 13 is disposed at an image forming operation position where it can perform image forming operation. A photoreceptor 1, which is an image carrier, has a photosensitive layer 12 formed on a conductive substrate 11, and rotates in the direction of the arrow shown.

The developing device 13 includes a non-magnetic sleeve 15, a stirring plate 17, and a regulating member 18 in the developing hopper 14, and a toner 21 for replenishment is stored in the upper part of the developing hopper 14 by a partition plate 19. A storage portion is formed, and an opening 19a for replenishing the toner 21 is formed at the bottom of the partition plate 19. A shutter member 24 is provided in the opening 19a.
is provided.

The non-magnetic sleeve 15 is made of a cylinder made of aluminum or the like, rotates in the direction of the arrow shown in the figure, and is applied with a predetermined bias by a bias power supply 22. Further, inside the non-magnetic sleeve 15, a magnet roll 16 magnetized with multiple poles is disposed.

The developer 20 is mainly composed of magnetic material and has a particle size of 20~
It consists of a mixture of a 200 μm carrier and a toner whose main component is resin. The carrier may be a magnetic material coated with a resin or a magnetic material mixed with a resin, and the toner may be a resin mixed with a magnetic material. The developing device 13 configured in this manner can be taken out of the main body of the device, which is a non-image forming operation position where no image forming operation is performed, by means of a support structure (not shown) such as a slide rail, and can be converted into another developing device. configured to be possible.

The operation in the above configuration will be explained next. An electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive layer 12 by a charging and exposing means (not shown), and the electrostatic latent image is sent to a developing area as the photoreceptor 1 rotates.

On the other hand, as the developer 20 is stirred by the stirring plate 17, the toner in the developer 20 is triboelectrically charged and has a charge opposite in polarity to that of the electrostatic latent image on the surface of the photosensitive layer 12. The developer 20 is contained in a non-magnetic sleeve 15.
It is attracted to the surface, transported by the rotation of the non-magnetic sleeve 15, passes through the regulating member 18, the amount of attraction is regulated, and is sent to the part closest to the photoreceptor 1. At this closest portion, the developer 20 forms a spike with the main pole N ₁ of the magnet roll 16 and comes into contact with the surface of the photosensitive layer 12 . Due to the Coulomb force between the charge of the toner and the electrostatic latent image, a portion of the toner is transferred to the surface of the photosensitive layer 12, and the electrostatic latent image is developed into a toner image 23. The developer 20 after development is further conveyed by the rotation of the non-magnetic sleeve 15 and stirred by the stirring plate 17. When such a development process is repeated, the toner concentration of the developer 20 decreases due to toner consumption, and the volume of the developer 20 decreases until the toner replenishment opening 19a
The level of the upper surface of the developer that was in contact with the opening 19a decreases, and a gap is created between the developer and the opening 19a, and the toner falls, thereby replenishing the toner 21. A shutter member 24 is provided at 19a.

The shutter member 24 is used for automatically replenishing toner as the developing device 13 moves away from the image forming operation position of the main body of the image forming apparatus where image forming processing is possible to the non-image forming operating position where image forming processing is not performed. The developing device 13 is moved to the position where the opening 19a is closed, the developing device 13 is set again to the image forming operation position, and after a predetermined number of image forming operations are repeated, the toner replenishing opening 19a is automatically moved to the position where the opening 19a is opened. It also has a mechanism that gives the shutter member 24 a predetermined amount of reciprocating rotational movement after the shutter member 24 is in the open state. FIG. 2 shows a case where the shutter member 24 is in a closed state, FIG. 3 shows a case where the shutter member 24 is in an open state, and FIG. Each state is shown below.

Next, the opening/closing mechanism of the shutter member 24 will be further explained.

FIG. 5 is an axial sectional view showing the drive mechanism for the shutter member 24 with the developing device 13 set in the main body of the image forming apparatus, and FIG. 6 is a perspective view thereof.
In the axial direction of the shutter member 24, the developing device 1
The shutter shaft member 25 of the shutter member 24 that protrudes outside the developing hopper 14 on the rear side of 3 is provided with a coupling ring A26, and this engagement convex portion 26a
and a groove 27a on the engagement surface of the coupling B27 provided on the image forming apparatus main body side are connected.
And part of the coupling B27 has ratchet 2.
8 is provided, and a stopper 29 is fixed to the main body frame 31 by a mounting plate 30 so as to engage with this ratchet 28. A driven gear 33 is attached to the end of the driven shaft 32 provided with the coupling ring B27.
A drive gear 35 that meshes with the driven gear 33 is attached to the drive gear 35 . This idle shaft 34 is driven by a paper feed roller shaft 38 from a drive system of the main body by a gear g36.
is transmitted to gear f37 attached to
39 and gear d40 to the idle shaft 34. In this embodiment, the paper feed roller is configured to rotate twice for one image forming operation, and when transmitting the drive to the idle shaft 34, the gear e3
9 and gear d40, the speed is reduced to 1/2, and the idle shaft 34 rotates once per image forming operation. Note that 42 in the figure is a bearing.

As shown in FIG. 6, the drive gear 35 attached to the idle shaft 34 is provided with only two teeth, and rotates once for each image forming operation from the illustrated fixed position. Stop at .
At this time, the two teeth of the driving gear 35 and the driven gear 3
3, the driven gear 33 is moved by a predetermined amount (one tooth of the ratchet 28). In the embodiment, the driven gear 33 has a module of 1.25 and a number of teeth of 32.
As a result, the coupling B27 on the driven shaft 32 is driven by a predetermined amount, and the stopper 29 engages with each tooth of the ratchet 28. This coupling B27 is provided with six teeth of the ratchet 28, and engages the stopper 29 with each tooth of the ratchet 28. The coupling B27 is fed by a predetermined amount until the mating convex portion 26a is driven by the coupling B27. In other words, in this embodiment, coupling B2
7 is fed from the normal position (the state shown in FIG. 8a), and four teeth of the ratchet 28 are fed before the drive is transmitted to the coupling A26, that is, the image forming operation is repeated four times (see FIG. 8). The drive is transmitted to the coupling ring A26 from the state shown in FIG. ). Further, it receives drive transmission from the drive gear 35, but the ratchet 28 of the coupling B27 has only six teeth, and the driven shaft 32 is spring-biased in the opposite direction to the direction in which it is fed. Even if it is fed more than this, when the drive gear 35 and the driven gear 33 are disengaged, it rotates in the opposite direction and the stopper 29 engages with the last tooth of the ratchet 28 to stop it. In other words, after the six-sheet copying operation, the coupling B27 repeats reciprocating rotation for each one-sheet copying operation. Further, the shutter shaft portion 25 is biased by a spring in the direction in which the shutter member 24 closes, and therefore, the shutter member 24 is in the open state shown in FIGS. 3 and 4 for each copying operation. I repeat. In this way, the shutter member 24 reciprocates, and the shutter protrusion 24a also repeats the reciprocating movement. Therefore, this operation agitates the toner 21 and prevents the toner 21 from remaining in a bridge shape above the developing hopper 14 and not falling downward.

Since the main body of the image forming apparatus repeats the normal image forming operation until the shutter member 24 starts to open, the non-magnetic sleeve 15 and stirring plate 17 in the developing device 13 are driven, and for example, the developer 20 Even if the level on the top surface of the developer 20 is uneven due to unevenness or the like, the level on the top surface of the developer 20 can be made uniform by the stirring action after about four image forming operations. That is, after the developing device is set in the image forming operation position of the main body of the apparatus, the shutter member 24 is not moved until the upper surface level of the developer 20 becomes uniform.
Since the toner is opened, it is possible to prevent erroneous oversupply of toner due to unevenness of the upper surface level of the developer 20. Although the above settings are used in this embodiment, the configuration is not limited to the above settings depending on the shape of the stirring plate 17 and the stirring method, and any settings may be used as long as the level on the upper surface of the developer 20 is made uniform. good.

Next, a description will be given of the operation when separating the developing device 13 from the image forming operation position of the main body where the image forming operation is possible to the non-image forming operation position where the image forming operation is not performed. The coupling A26 and the coupling B27, which had been in an engaged state until then, are connected to the developing device 13.
The engagement state is released by separating the image forming operation position from the image forming operation position to the non-image forming operation position (see FIG. 7). As mentioned above, since the shutter member 24 is always biased by the spring so as to be in the closed state, the shutter member 24 is brought into the closed state at the same time as the engagement is released, thereby preventing the toner 21 from falling into the developer 20. do. Further, the coupling B27 moves in the axial direction to the position where it abuts against the engagement pin 43 by the operation of the compression spring 41, and at that time, the coupling B27
The engagement between the ratchet 28 of 27 and the stopper 29 is also released, and the driven shaft 32 rotates in the opposite direction to the feeding direction due to the spring bias. At this time, the stop pin 44 provided upright on the driven gear 33 attached to the driven shaft 32 comes into contact with a locking member (not shown), and the driven shaft 32 and the coupling B27 are stopped at the fixed position (the state shown in FIG. 8a). do.

Then, when the developing device 13 is set in the main body again, the state shown in FIG. 5 is obtained and the same operation as described above is repeated.

In this embodiment, the shutter member 24 and the coupling B27 are configured to return to their predetermined positions when the developing device 13 is attached and detached from the main body along with the moving operation of the developing device 13, but a part of the image forming apparatus main body is In the case of a device that can be opened along the transfer paper conveyance path, the shutter member 24 and the coupling B2 are
If 7 is configured so that it returns to a predetermined position, it is possible to prevent excessive replenishment of toner due to deviation of the developer due to opening of the main body, as in the present embodiment.

In addition, without using mechanical means as in this example,
It is also possible to control it, for example by electrical means.

〔Effect of the invention〕

As described above in detail, the image forming apparatus of the present invention has a simple configuration that prevents excessive toner replenishment.
A stable image can be formed over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional developing device, FIG. 2 is a block diagram of the vicinity of the developing section of an image forming apparatus showing an embodiment of the present invention, and FIGS. 3 and 4 are diagrams of the vicinity of the toner replenishment opening. 5 and 7 are cross-sectional views showing the opening/closing mechanism of the shutter member, FIG. 6 is a perspective view showing the opening/closing mechanism of the shutter member, and FIG. 8 shows the engagement relationship between coupling A and coupling B. FIG. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 13...Developing device, 15...Nonmagnetic sleeve, 20...Developer, 24...Shutter member, 26...Coupling A, 27...Coupling B, 28...Ratchet.

Claims (1)

[Scope of Claims] 1. An image forming apparatus comprising: a developing device having a developer for developing an electrostatic latent image on an image carrier; and a replenishing means for replenishing the developing device with replenishing developer; The replenishing means is stopped for a predetermined image forming operation period after the completion of a moving operation in which the developing device moves from a non-image forming operation position where the image forming operation is not performed to an image forming operation position where the image forming apparatus body performs the image forming operation. An image forming apparatus characterized by: 2. Claim 1, wherein the developing device is detachable from the main body of the image forming apparatus, and the moving operation of the developing device is an attaching operation.
The image forming apparatus described in . 3. The first aspect of the present invention is characterized in that a part of the main body of the image forming apparatus can be opened and closed, and the moving operation of the developing device is caused by the opening and closing operation of a part of the main body of the image forming apparatus. The image forming apparatus described in . 4. The image forming apparatus according to claim 1, wherein the replenishing means replenishes the developer in accordance with changes in the upper surface level of the developer in the developing device.