JPH0648407B2 - Development device - Google Patents

Description

The present invention relates to a two-component developing device using a dry two-component developer of an electronic copying machine, and more particularly, to replenishing a developing sleeve with the developer.・
The present invention relates to a device for carrying, mixing and stirring independently.

[Conventional technology]

In this type of two-component developing device, each process of replenishing a developing sleeve with a developer, peeling from the sleeve, carrying, and mixing / stirring the toner and the carrier of the developer are independently performed.

FIG. 14 and FIG. 15 show an example of a conventional example. The upper screw 24 for replenishing the developing sleeve 3 with the developer, the stripping / conveyance of the developer from the sleeve 3, and the stirring and mixing with the supplied toner. Although it is composed of the lower screw 25, since the screws 24 and 25 are arranged in the same chamber, the developed developer is repeatedly used, and the mixing and stirring action with the toner is insufficient, resulting in uneven density, streak fogging, and the like. There is a problem in image quality such as ground fog and reversal fog. That is, the balance change of the toner consumed and the toner supplied in the longitudinal direction of the sleeve 3 is large, and an appropriate density cannot be obtained.

Further, Japanese Patent Laid-Open No. 51-15443 discloses a system in which two screws are made longer than the length of the developing sleeve and toner is replenished to the extended region, but one screw supplies and uses the developer to the developing sleeve. After that, the developer is transported, and the other screws are completely separated from the sleeve, and only serve to mix and transport the supplied toner and developer.
It is difficult to keep the toner density of the developer constant, and there is a drawback that a predetermined image density decrease or density unevenness in the axial direction of the developing sleeve occurs.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device which is constructed so that a mixture of two components can be utilized for development and which eliminates the problems of the conventional example.

(B) Structure of the Invention [Means for Solving the Problems] In the developing device of the present invention, a developing sleeve for carrying and carrying a two-component developer containing toner and carrier, and an opening for each developing sleeve. Two developer paths arranged one above the other, one guiding the transport of the developer supplied to the developing sleeve and the other guiding the transport of the developer removed from the developing sleeve after passing through the developing region, Disposed in the upper developer passage, arranged in the lower developer passage and an upper conveyance means for stirring and conveying the developer along the developing sleeve longitudinal direction,
Lower conveying means for stirring and conveying the developer along the longitudinal direction of the developing sleeve, wherein the upper and lower developer passages are extended further outward than the end portion in the longitudinal direction of the developing sleeve, An ascending communication path for transferring the developer from the lower developer passage to the upper developer passage is provided in this extension portion, and the developer conveying force of the upper developer conveying means is set to the developer of the lower developer conveying means. The developing device is characterized by being larger than the carrying force.

[Operation] In the present invention, the developer is transferred from the lower developer passage to the upper developer passage on the outer side of the longitudinal end portion of the developing sleeve. Therefore, in the ascending communication passage, gravity impedes the upward movement of the developer. In the present invention, the developer transporting force of the upper transporting means lowers the developer transporting force of the upper transporting means. Since it is larger than that, it is possible to prevent the developer from staying in a dense state in the ascending communication passage.

[Embodiment] FIG. 1 shows a first embodiment of the present invention. 1 is an image carrier,
2 is a developing device, 3 is a developing sleeve which rotates in the forward direction with the image carrier 1, the developer is conveyed to the image carrier side by the magnet 3a arranged in the sleeve, and the developing pole S1 forms a magnetic brush. Develop corresponding to the electrostatic latent image.

The developing device 2 is divided into upper and lower passages 2a and 2b by a horizontal partition plate 5, and upper and lower passages 2a and 2b are formed, and an upper screw (a member for moving the developer) 6 and a lower screw 7 are provided in the respective passages to face the developing sleeve 3. Then, the both ends A and B are extended longer than the sleeve 1, and the partition plate 5 is cut at the screw ends to form the connecting portions 5a and 5b of the upper and lower passages 2a and 2b. Reference numeral 10 denotes a shaftless screw provided in the upper and lower connecting portions 5a of the extension portion A, which is driven continuously and integrally with the screws of the upper and lower screws 6 and 7. Reference numeral 11 is a toner supply port provided on the upper wall of the developing device above the screw 10, and 9 is a toner concentration detector in the developer.

As shown in FIG. 1, when the sleeve 3 is rotated in the forward direction with the image carrier 1, the developed developer falls from the connecting portion 5b of the extension portion B into the lower passage 2b and is extended by the lower screw 7. The developer circulates so that it is conveyed to the portion A, is pushed up to the upper passage 2a by the shaftless screw 10 provided in the connecting portion 5a of the extension portion A, and is conveyed to the developing sleeve side by the upper screw 6.

During that time, when a toner concentration decrease signal is transmitted from the detector 9, a predetermined amount of new toner is supplied from the port 11 and the screw 1
When it is 0, it is sent to the upper passage 2a while being sufficiently stirred and mixed, and is conveyed along the sleeve 3 by the screw 6. The developer magnetically adhered to the surface of the sleeve 3 is applied to the sleeve 3 by the doctor blade 4 and the carrier pole N1 of the magnet, and the magnetic pole is formed at the developing pole S1 for development. .

The developed developer that has contributed to the development is accompanied by the sleeve 3, passes through the carrier leakage preventing magnetic blade 12 and enters the lower passage 2b, and is sent toward the extension A by the screw 7.
In the meantime, for example, the scraper 5a formed at the tip of the partition plate
Most of it is stripped off and transported.

FIG. 3 shows an embodiment in which the developing sleeve 3 is rotated in the direction opposite to that of the image carrier 1. In this case, the rotation directions of the screws 6 and 7 are also opposite to those in FIG. The arrangement relationship of the magnetic blades 12 is also reversed. That is, the lower passage 2b serves as a developing process passage, and the upper passage 2a serves as a developed developer transport passage.

The extension B may be omitted and may have a length substantially equal to that of the developing sleeve 3. Further, the toner supply position is not limited to the illustrated position, and the supply port is provided in the communication passage or the upstream side (the side to which the developed developer is sent). Further, as the member 10 for moving the developer in the upper and lower connecting portions 5a, a chain conveyor other than the illustrated example can be used.

FIG. 4 shows that the screws 6 and 7, and the developing device box 2 that surrounds the screws are formed to have substantially the same length as the developing sleeve 1, and the upper and lower connecting portions 5a are connected by the tube 12 to form an extension portion A. This is an embodiment in which the shaft screw 10 is arranged.

In this case, there is an advantage that the volume space of the extension portion A is smaller than that in the embodiment of FIG.

In the embodiment shown in FIG. 5, the tubular bodies 13 and 14 communicating with the upper and lower passages 2a and 2b are superposed on each other in the front and rear direction, and the connecting portions 5a are formed by communicating with each other at their intersections as shown in FIG. The screws 15 and 16 are provided in the tubular bodies 13 and 14, respectively.

FIG. 7 shows an embodiment in which the extension pipe 2b1 of the lower passage 2b rises obliquely upward and cross-communicates with the straight extension pipe 2a1 of the upper passage 2a to form the extension A and the communication portion 5a. The upper and lower screws 15 and 16 are crossed as in the example of FIG.

FIG. 8 shows a modification of the example of FIG. 4 in which the screws 6, 7, and 10 are 1
It is a book.

In the embodiment of FIGS. 9 and 10, the upper and lower passages 2
The relationship between the connecting portion 5a formed on the extension portion A of 1a and 21b and the screws 6 and 7 and 10 is the same as that in the above embodiment.

The developer, which contributes to the development and whose toner concentration is lowered, is accumulated at the rear bottom portion of the lower passage 21b of the case of the developing device 2, and is conveyed to the connecting portion 5a of the extension portion A of the developing sleeve 3 by the lower screw 7. At this time, an appropriate amount of toner is supplied by a stirring rod 26 by a signal from a toner concentration detector (not shown) from a toner hopper 27 provided in substantially the entire length of the developing device case via a long replenishing port 34 facing the substantially entire length of the lower screw 7. Then, the developer, which is carried together in the connecting portion 5a, is sufficiently agitated and mixed by the screw 10 and has a prescribed toner concentration, is carried by the upper screw 6 in the axial direction of the upper sleeve 6.

In the previous example, the upper screw 6 faces the developing sleeve 3 as shown in FIG. 1, but in the embodiment shown in FIG.
The partition 28 is surrounded by 8 and is provided with a developer supply opening 29 toward the sleeve 3. A developer reservoir 32 is provided facing one side of the sleeve 3 by the partition plate 30, the carrier pushing-back member 31, and the blade 4.

The developer supply opening 29 is provided in the partition wall 28 toward the sleeve 3 so as to increase the opening size in the direction in which the developer is conveyed by the screw 6. 11 to 14
The figure shows an example thereof. FIGS. 10 and 11 show the connection slot having the opening 29 gradually increasing in width from the upstream side to the downstream side, and the lower side 29a thereof being inclined downwardly toward the downstream side, and FIG. 12 shows the slot opening. This is an example of division into window hole shapes.

As shown in FIG. 7, in the developer closed circuit, the extension portion 2 is provided in the portion which is transferred from the connection portion 2b1 to the developing side passage 2a.
If the inlet of a1 or the inlet of the connecting portion 5a in FIG. 8 is narrowed, the developer may stay in the narrowed portion and still cause some density unevenness in the sleeve axial direction. . Therefore, as shown in FIG. 13, when the supply opening 29a is formed such that the front side is small and the back side is large, it is possible to eliminate uneven density in the sleeve axial direction.

In the yarn in which the developer of the present invention circulates in one direction in the closed circuit, the carry amount of the upper screw 6 needs to be larger than the carry amount of the lower screw 7. The means are: 1, the pitch of the upper screw> the pitch of the lower screw (when the rotation speed and the inner and outer diameters of the screw are the same) 2, the rotation speed of the upper screw> the rotation speed of the lower screw (the inner and outer diameters of the screw, If the pitch is the same) 3, Outer diameter of the upper screw> Outer diameter of the lower screw (when the screw inner diameter, pitch and rotation speed are the same) 4, Inside diameter of the upper screw <Inner diameter of the lower screw (Outer diameter of the screw, pitch, With the same rotation speed), this configuration solves the problem that the toner accumulates at the connecting portion 5a where the upper and lower screws merge, causing blocking, and the screw being broken or the container being broken.

C. Effect of the Invention As described above, the upper and lower screws function independently as two passages divided into upper and lower portions, one of which serves as a developer replenishing and conveying path to the developing sleeve and the other serves as a developed developer conveying path. As a result, the repeated use of the developer after use is reduced and uneven density in the axial direction of the sleeve is eliminated.

Even if the upper and lower two passages are extremely close to each other, the replenishment and the developed ones are not mixed. Therefore, the developing device is constructed in a very small size.

Further, since the above-mentioned two passages are extended longer than the developing sleeve and the extended portion is used as the agitation / mixing chamber, the agitation and mixing of the carrier and the toner are sufficiently performed, and problems such as uneven density, streak fog, background fog, and reverse fog are caused. Solvable.

Since it has a simple structure that is small and lightweight, it is easy to deal with high speed. Since the developer is circulated by one drive system without requiring any special stirring means, there is a great effect on labor saving.

[Brief description of drawings]

1 and 2 are a cross-sectional front view and a vertical sectional side view of the present invention,
FIG. 3 is a cross-sectional front view of another embodiment, FIGS. 4 and 5 are longitudinal side views of a part of another embodiment, and FIG. 6 is a cross-sectional side view of FIG. FIG. 8 is a vertical sectional side view of another embodiment of the connecting portion of the upper and lower passages, and FIGS. 9 and 10 are transverse sectional front views and vertical sectional side views of still another embodiment, FIGS. 11 to 13. Are front views of various embodiments of the developer supply opening to the developing sleeve, and FIGS. 14 and 15 are a transverse front view and a vertical side view of a conventional example. 1 ... Image bearing member, 2 ... Developing device, 2a / 2b ... Passage,
3 ... Development sleeve, 4 ... Doctor blade, 5 ... Partition plate, 5a ... Scraper, 6/7/10 ... Conveying screw, 11 ... Toner supply port, 12 ... Scraper, 1
3 ... Toner density detector.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-61-77877 (JP, A) JP-A-59-50467 (JP, A) JP-A-59-50466 (JP, A) JP-A-58- 220157 (JP, A) Actual opening Sho 58-13540 (JP, U) Actual opening Sho 60-193558 (JP, U) Actual opening Sho 55-6996 (JP, U)

Claims (1)

[Claims] 1. A developing sleeve that carries and conveys a two-component developer containing toner and carrier, and each has an opening to the developing sleeve, and one guides the conveyance of the developer supplied to the developing sleeve. The other is disposed in the upper developer passage and the two developer passages arranged vertically to guide the conveyance of the developer removed from the developing sleeve after passing through the developing area. The upper and lower developer passages, and the upper and lower developer passages, which are arranged in the lower developer passage and are agitated and conveyed, along the longitudinal direction of the developing sleeve. Is extended further outward than the end portion in the longitudinal direction of the developing sleeve, and an ascending communication passage for transferring the developer from the lower developer passage to the upper developer passage is provided in this extended portion, and Agent delivery means Developing apparatus is characterized in that a larger than the developer conveying force of the lower developer conveying means developer conveying force.