JP2541754Y2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a dry-type developing apparatus using a powder developer.

[Prior Art] Dry-type development using a powder developer in an image forming apparatus such as a copying machine, a facsimile, or a printer that forms an electrostatic latent image on a latent image carrier and visualizes the electrostatic latent image. The device has been widely adopted.

FIG. 3 shows a conventional example, in which a two-component developer containing at least a toner and a carrier is accommodated in a developing container 101 of the developing device exemplified here. This developer is magnetically supported on a cylindrical sleeve-shaped developer holding member 103 having a magnet body 102 provided therein, and the electrostatic charge formed on the surface of the latent image holding member 104 by the held developer. The latent image is developed into a visible image. In this example, a drum-shaped photoconductor is used as the latent image carrier.

Here, the developer holding member 103 that rotates counterclockwise
Carries and transports a developer for visualizing the electrostatic latent image formed on the latent image carrier 104.
The first developer transport rotation member 105 for supplying the developer to the peripheral surface of the 103 is configured as follows.

As shown in FIGS. 3 and 4, the first developer transport rotation member 105 includes a hollow shaft portion 105a extending substantially parallel to the developer carrying member 103, and a radially extending outer circumferential surface of the hollow shaft portion 105a. And a developer pumping blade 105b integrally formed with
A screw member wound spirally around this
105c. On the other hand, in the hollow shaft portion 105a, the shaft 10
A second developer transport rotation member 106 provided with a screw portion as shown in FIG. 6A is arranged. The two developer conveying rotary members 105 and 106 are driven to rotate at different linear velocities, for example, the latter is twice as fast as the former.

The developer in the developing container 101 is transported in the axial direction of the developer carrying member 103 with the rotation of the first developer transport rotating member 105 among them. In other words, the developer is conveyed in the direction of arrow A. At this time, the developer is pumped up in the circumferential direction of the hollow shaft portion 105a by the pumping action of the developer pumping blades 105b, and the developer is supplied to the developer carrying member 103. Is supplied to the peripheral surface.

In the developing device of this example, toner is supplied from a toner cartridge (not shown) into the developer in the developing container 101 by a toner supply roller 107. Can also supply toner.

As shown in FIG. 4, the developing container 101 has a cylindrical portion 101a.
Is formed so that toner is supplied from a toner hopper (not shown) through an opening 108 provided in the cylindrical portion 101a. On the other hand, the hollow shaft portion 105a of the first developer conveying rotary member 105, its one axial end, inlet 105a ₁ for introducing a replenished toner and the developer to the hollow shaft portion 105a is formed , yet the other axial end of the hollow shaft portion 105a, the outlet 105a ₂ for discharging the developer introduced into the hollow shaft portion 105a to the hollow shaft outer is formed.

The toner replenished through the opening 108, together with the developer sent in the direction of arrow A, enters the inlet 10 of the hollow shaft portion 105a.
5a ₁ enters the hollow shaft portion from the second developer transport rotation member 106
While stirring the replenishment toner and the developer introduced into the hollow shaft portion from the introduction port 105a ₁ , the first developer transport rotation member 10
5 by conveying in the opposite direction B developer conveying direction, is rotationally driven so as to discharge from the discharge port 105a ₂ the developer. The discharged developer is subsequently transported in the direction of arrow A by the first developer transport rotation member 105, and re-enters the hollow shaft together with the supplied toner. In this way, the developer circulates inside and outside the first developer transport rotation member 105 while being supplied with toner. Incidentally, such a developing device of the dual mixing system is disclosed in, for example,
It is shown in, for example, JP-A-62-19883.

In the developing device having the above configuration, the hollow shaft portion 1 from the inlet 105a ₁
When the toner and the developer contained in 05a are sent through the hollow shaft portion 105a by the second developer conveying rotation member 106, there is a problem that the toner and the developer are not mixed and stirred uniformly and uniformly.

For example, as shown in FIG. 5 (a), the replenished toner T and the developer G are transported along the screw surface of the second developer transport rotating member 106. At this time, As shown in FIG. 3B, the toner T slips off the developer G, and as shown in FIG.
The toner T is not uniformly dispersed therein. That is, the mixing and stirring properties with the replenishment toner were poor.
When the mixing and agitation properties are deteriorated, some of the toner does not rise to a predetermined charge amount, which causes a background image stain on a visible image. Further, if the mixing and stirring properties are deteriorated, the bulk toner is not pulverized, but remains in the developer as it is, and a black spot may appear on the image to cause an abnormal image.

After all, in the conventional developing device, although the developer transportability by the second developer transport rotating member is good, the flow of the developer during this transport is simple, and the developer flows so as to slip down regularly. Therefore, it is difficult to mix and stir the toner and the developer uniformly.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing apparatus which eliminates the above-mentioned conventional drawbacks, can uniformly mix and stir the toner and the developer when circulating and transporting the developer, and can suppress an increase in cost. Is to do.

[Means for solving the problem]

In order to achieve the above object, the present invention carries and transports a developer container containing a two-component developer and a developer for visualizing an electrostatic latent image formed on a latent image carrier. A developer carrying member, a hollow shaft extending substantially parallel to the developer carrying member, and a developer pumping blade integrally formed on an outer peripheral surface of the hollow shaft; The first developer that supplies the developer to the peripheral surface of the developer carrying member by the action of the developer pumping blade while transporting the developer in the developing container in the axial direction of the developer carrying member with the rotation of A transport rotating member, and a second developer transport rotating member disposed in the hollow shaft portion, wherein the supplied toner and developer are introduced into the hollow shaft portion at one axial end of the hollow shaft portion. The hollow shaft portion is formed at the other axial end of the hollow shaft portion. Outlet for discharging the developer introduced into the shank to the hollow shaft outer is formed, the second
The developer transport rotating member transports the replenishment toner and the developer introduced into the hollow shaft portion from the introduction port while stirring the developer and the developer in a direction opposite to the developer transport direction by the first developer transport rotating member. In a developing device that is rotationally driven to discharge the developer from the discharge port, the toner and the developer conveyed by the second developer conveying rotation member are captured and pumped up, and then the toner and the developer are removed. A developing device is characterized in that a developer catching portion for dropping its own weight toward the second developer conveying rotation member is formed on the inner wall surface of the hollow shaft portion itself.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing the developing device of the present embodiment. The basic structure and operation of the developing device shown here are the same as those of the conventional developing device described above with reference to FIGS. 3 and 4. There is no difference. In other words, the developing device shown in FIG. 1 also carries a developing container 1 for storing a two-component developer and a developer for visualizing an electrostatic latent image formed on the latent image carrier 4. Developer transport member 3 that transports the developer, first developer transport rotary member 5,
A second developer transport rotation member 6; the first developer transport rotation member 5 includes a hollow shaft portion 5a extending substantially parallel to the developer carrying member 3 in which the magnet body 2 is mounted; Developer pumping blade formed radially and integrally on the outer surface of the part
5b and screw member integrally wound around it
5c, and while the developer in the developing container 1 is being conveyed in the axial direction of the developer carrying member 3 with the rotation of the hollow shaft portion 5a, the developer is pumped up by the developer pumping blade 5b. The developer is supplied to the peripheral surface of the developer carrying member 3. The second developer transport rotation member 6 is disposed inside the hollow shaft portion 5a. At one axial end of the hollow shaft portion 5a, although not shown in FIG. An inlet for introducing the developer into the hollow shaft portion is formed, and at the other axial end of the hollow shaft portion 5a, the developer introduced into the hollow shaft portion 5a is discharged out of the hollow shaft portion 5a. A discharge port (also not shown) is formed. The second developer transport rotation member 6 includes:
A direction opposite to the developer transport direction (A direction in FIG. 4) of the developer by the first developer transport rotary member 5 while stirring the replenishment toner and the developer introduced into the hollow shaft portion 5a from the inlet. (Also in the direction B in FIG. 4), and is rotated so as to discharge the developer from the discharge port.

Here, the difference from the conventional developing device illustrated in FIGS. 3 to 5 is that, as shown in FIG. 2A, the inner peripheral surface of the hollow shaft portion 5a, that is, the inner wall surface itself, The point is that the grooves 10 extending in the axial direction are engraved at a predetermined pitch in the circumferential direction. Other configurations are the same as those of the conventional developing device, and therefore, further description of the same portions will be omitted.

As described above, in this example, the second developer transport rotation member 6 is at a higher speed than the first developer transport rotation member 5,
The rotation is performed in the same direction as the first developer transport rotation member 5. At this time, the replenished toner T and the developer G are transported in the hollow shaft portion 5 a by the second developer transport rotation member 6. . At this time, as shown in FIG. 2B, the toner and the developer conveyed by the second developer conveying rotation member 6 are
It enters the groove 10, is caught therein, and is pumped up in the circumferential direction of the inner wall surface of the hollow shaft portion 5a. That is, the toner is captured together with the developer in the groove 10 and is pumped up in the circumferential direction of the inner wall surface of the hollow shaft portion 5a. After that, the toner and the developer are rotated from the groove 10 by the second developer conveying rotation. It falls by its own weight toward the member 6. At this time, as shown in FIG. 2 (c), the toner is mixed with the developer. Then, while such an operation is being performed, the toner and the developer are conveyed in the axial direction along the screw surface of the second developer conveyance rotating member 6 as shown in FIG.

As described above, since the toner and the developer are conveyed while falling and flowing, the toner and the developer are uniformly mixed and stirred during this time. This makes it possible to charge each toner to a predetermined charge amount. In addition, when the agglomerated toner is present, it is caught in the groove 10 and then crushed when dropped by its own weight, so that the toner can be uniformly dispersed in the developer. Becomes Thus, the toner and developer are irregular and
Because of the complicated flow, the mixing and stirring properties of the two can be further improved.

The groove 10 captures and pumps up the toner and the developer conveyed by the second developer conveying rotation member 6, and then drops the toner and the developer toward the second developer conveying rotation member 6 by its own weight. This forms one configuration example of the developer capturing section, and the developer capturing section is formed on the inner wall surface of the hollow shaft section 5a itself. The developer catching portion may be formed in a spiral groove or a blade shape, or may be configured such that one and one protrusion are uniformly formed on the inner wall surface of the hollow shaft portion 5a.
In any case, the inner wall surface of the hollow shaft portion 5a may be made uneven so that the developer is easily captured.

Since the developer capturing portion as described above is formed on the inner wall surface of the hollow shaft portion 5a, the capturing portion is separate from the hollow shaft portion 5a, compared with a case where the capturing portion is inserted into the hollow shaft portion 5a. The structure of the developing device can be simplified and the cost can be reduced.

The present invention can also be applied to a developing device in which the developer carrying member rotates, the magnet body inside thereof rotates, or the developer carrying member is fixed immovably, and only the magnet body rotates.

[Effect of the invention]

According to the present invention, when the developer is transported by the second developer transport rotating member, an irregular flow of the developer is created, so that the replenished toner and the developer are evenly and uniformly. Mixing and stirring can be performed. As a result, the toner can be charged with a sufficient charge amount, so that the image quality can be further improved, and the background stain is less likely to occur. Further, when there is a lump of toner, it can be easily crushed, so that the occurrence of abnormal images such as spots can be prevented.
In addition, since the developer catching portion is formed on the inner wall surface of the hollow shaft portion, it is possible to effectively suppress the complexity of the structure of the developing device and an increase in cost thereof.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a dry developing device according to an embodiment of the present invention,
2 (a) to 2 (d) are explanatory views showing a state in which toner and developer fall and flow by a developer catching section of a first developer transport rotating member, and FIG. 3 is a view showing a conventional dry developing apparatus. FIG. 4 is a schematic cross-sectional view, FIG. 4 is a cross-sectional view showing first and second developer conveying and rotating members of the conventional example, and FIGS. FIG. 4 is an explanatory diagram illustrating a state in which a developer is transported. DESCRIPTION OF SYMBOLS 1 ... Development container, 3 ... Developer carrying member 5 ... 1st developer conveyance rotation member, 5a ... Hollow shaft part 5b ... Developer pumping blade, 6 ... 2nd developer conveyance rotation member

Claims (1)

(57) [Scope of request for utility model registration] A developing container containing a two-component developer;
A developer carrying member for carrying and transporting a developer for visualizing the electrostatic latent image formed on the latent image carrier; a hollow shaft extending substantially parallel to the developer carrying member; While having a developer pumping blade integrally formed on the outer peripheral surface of the shaft portion, while transporting the developer in the developing container in the axial direction of the developer carrying member with the rotation of the hollow shaft portion, A first developer conveying rotary member for supplying the developer to the peripheral surface of the developer carrying member by a pumping action of a developer pumping blade; and a second developer conveying rotary member disposed in the hollow shaft portion. An inlet for introducing the supplied toner and developer into the hollow shaft is formed at one axial end of the hollow shaft, and a hollow is formed at the other axial end of the hollow shaft. A discharge port for discharging the developer introduced into the shaft portion to the outside of the hollow shaft portion is formed. The second developer transport rotation member is configured to stir the replenishment toner and the developer introduced into the hollow shaft portion from the introduction port while stirring the developer and the developer in a direction opposite to the developer transport direction by the first developer transport rotation member. In a developing device which is transported and rotationally driven to discharge the developer from the discharge port, the toner and the developer transported by the second developer transport rotating member are captured and pumped, and then the toner and A developing device, wherein a developer catching portion for dropping the developer by its own weight toward a second developer conveying rotation member is formed on the inner wall surface of the hollow shaft portion itself.