JPH11174800A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the insufficient stirring state of developer and to eliminate the lowering and the irregularity of image density by sufficiently stirring toner and carrier at the initial stage of the stirring and transferring action of the developer by providing the part of a second communicating path with a toner supply port and a third developer stirring and transf erring means stirring and transferring the developer. SOLUTION: The developer in a developer container is made to circulate and transferred by the route of a first developer chamber 7, a first communicating path 11, a second developer chamber 8 and the second communicating path 12. Then, the toner supply port 13a supplying the toner to the developer and at least one or more third developer stirring and transferring means 15 stirring and transferring the developer are disposed at the part of the path 12. Besides, the path 12 is disposed in an area outside the end surface of a developing roller 3 in the longitudinal direction. Thus, since the newly supplied toner is sufficiently stirred with the developer in a developing device before it enters the chamber 7 and the concentration thereof is uniformized before it enters the chamber 8, triboelectrification is increased. Besides, the toner is prevented from being retained at the end part of the developing roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, as a developing device for an electrostatic latent image formed on the surface of an image carrier such as a photoreceptor or a dielectric, toner, which is a coloring fine particle, is made of iron powder called a carrier. Some use a two-component developer mixed with the above.

In such a developing device, there is provided means for transferring a developer obtained by stirring and mixing a toner and a carrier in a developer container in a predetermined direction.

FIG. 3 shows an example of such a developing device.
(A) is a cross-sectional side view, (b) is a longitudinal plan view.

Reference numeral 100 denotes an image bearing member as a member to be developed, which is, for example, a rotating drum type electrophotographic photosensitive member. The photoreceptor is rotated at a predetermined peripheral speed in the clockwise direction of the arrow, and an electrostatic latent image corresponding to the target image information is formed on the surface thereof by a latent image forming process unit (not shown).

[0006] Reference numeral 1 denotes a developing device,
And the photoconductor 100
The electrostatic latent image on the surface is developed as a toner image.

In the developing device 1, reference numeral 2 denotes a developing container, in which a two-component developer (not shown) in which a toner and a carrier are mixed is accommodated.

Reference numeral 3 denotes a developing sleeve as a developing member, which is disposed on the front side of the developing container 2 so that both shaft portions are rotatably supported between the rear side wall 4 and the front side wall 5 of the developing container. The rear half of the developing sleeve 3 is
And the front half surface is exposed outside the developing container 2.

In the developing device 1, the developing sleeve 3 is disposed so as to face the photosensitive member 100 with a predetermined gap therebetween. The facing portion between the developing sleeve 3 and the photosensitive member 100 is a developing section D. .

Reference numeral 6 denotes a partition member (partition plate) which divides the inside of the developer container 2 into two chambers 7 and 8 substantially parallel to the length of the developing sleeve 3, and is provided so as to protrude from the bottom wall of the developer container 2. I have. The chambers 8 on the developing sleeve 3 side of the two chambers 7.8
Is a second developer chamber, and a chamber 7 on the opposite side of the second developer chamber 8 from the developing sleeve 3 side is a first developer chamber.

Reference numerals 9 and 10 denote the first and second developer chambers 7.
Rotary screw shafts as first and second developer stirring / transporting means, respectively, disposed in the inside 8. The two rotary screw shafts 9 and 10 are respectively provided with first and second developer chambers 7 and 8.
, And has a length dimension substantially corresponding to the longitudinal dimension of the inside of the developing container 2.
It is arranged so as to be freely rotatable.

Development sleeve 3, rotating screw shaft 9.1
Numerals 0 are rotationally driven in a direction of an arrow at a predetermined peripheral speed by a drive system (not shown).

The developer in the first developing chamber 7 is rotated in one direction along the longitudinal direction of the chamber 7, in this embodiment, by the rotation of the rotary screw shaft 9 as the first developer stirring / transporting means in the developing chamber. The developing container 2 is transported while being stirred in the direction of arrow A from the front side wall 5 side to the rear side wall 4 side.

The developer in the second developing chamber 8 is rotated by a rotating screw shaft 10 as a second developer stirring / transferring means in the developing chamber, so that the first rotating screw shaft 9 is rotated.
In the direction opposite to the developer transfer direction, in this example, the developer container 2
Is transported while being stirred along the length of the chamber 8 in the direction of arrow B from the rear side wall 4 side to the front side wall 5 side. The partition member 6 prevents mixing of the developer stirred and transferred in the first developer chamber 7 and the developer stirred and transferred in the second developer chamber 8.

Reference numeral 11 denotes a portion between the downstream side of the first developer chamber 6 in the developer transfer direction and the upstream side of the second developer chamber 7 in the developer transfer direction (the back side wall 4 of the developing container 2 and the side of the partition member 6). A first communication path (developer circulation path) 11 provided between the first developer chamber 6 and the downstream side of the second developer chamber 7 in the developer transfer direction.
(Between the back side wall 4 of the developing container 2 and the end of the partition member 6 on the side thereof).
This is a communication path (developer circulation path).

Therefore, the developer in the developer container 2 of the developing device 1 is rotated by the first and second screw shafts 9 and 10 so that the first developer chamber 7, the first communication passage 11, The toner is circulated and transferred while being stirred and mixed in the second developer chamber 8 and the second communication path 12. By stirring and transferring the developer, the toner concentration of the developer is made uniform, and charge is applied to the toner.

A part of the developer transported while being stirred in the second developer chamber 8 by the second rotary screw shaft 9 is carried on the rotary developing sleeve 3 and transported to the developing section D, where With this toner, the electrostatic latent image on the surface of the photoconductor 100 is developed as a toner image. A predetermined developing bias is applied to the developing sleeve 3 from a power source (not shown).

The developer on the developing sleeve 3 which has passed the developing section D is transferred to the developer container 2 by the subsequent rotation of the developing sleeve.
It is transported back inside.

The toner concentration of the developer in the developing container 2 is consumed for developing the electrostatic latent image on the photosensitive member 100, and decreases with the consumption. Therefore, a means (not shown) for detecting the toner concentration of the developer in the developing container 2 is provided, and when the toner concentration detected by the detecting means decreases to an allowable lower limit, the toner supply hopper 13 By performing the operation of replenishing the toner in the first developer chamber 7, the toner concentration of the developer in the developing container 2 is always maintained and controlled in a predetermined concentration range.

[0020]

[Problems to be solved by the invention]. However, in the prior art, as a first problem, the function of the first developer stirring / transfer means 9 for stirring / transferring the developer in the first developer chamber 7 is biased toward the transfer rather than the stirring of the developer. For this reason, the developer in the first developer chamber 7 may be conveyed from the first communication path 11 into the second developer chamber 8 on the side of the developing sleeve 3 as a developing member without being sufficiently stirred. .

The toner supply port of the hopper 13 for supplying toner is placed on the first developer agitating / transferring means 9 in the area shown by the hatched portion in FIG. In this case, the developer in the first developer chamber 7 supplied with toner from the hopper 13 is conveyed into the second developer chamber 8 on the side of the developing sleeve 3 without being sufficiently stirred. There is.

If the developer is not sufficiently agitated, the charge per unit weight of toner (tribo) applied by the agitation becomes insufficient, and if the developer is conveyed to the developing sleeve 3 side, the image density becomes uneven. There was something.

[0023] As a second problem, the dimension L1 between the rear side wall 4 and the front side wall 5 of the developer container 2 is
, The downstream end 3 a of the developing sleeve 3 in the developer transfer direction B in the second developer chamber 8 is caused by the flow variation of the developer in the second developer chamber 8. The developer is close to the vicinity 14 of the front side wall 5 of the developer container 2, which is a curved portion and in which the developer is apt to be accumulated. In some cases, a decrease in density occurred at the end of the image drawn in FIG.

Accordingly, a first object of the present invention is to solve the problem of insufficient stirring of the developer and to sufficiently stir the toner and the carrier in the initial stage of the stirring and transfer of the developer in this type of developing device. Accordingly, it is possible to provide a larger tribo, and to eliminate a decrease in image density and unevenness.

A second object of the present invention is to prevent insufficient stirring of the developer agitated / transferred in the developing device (developer container) due to stagnation near the developing member, thereby reducing the amount of toner in the developer. When replenishing toner to a developer having a reduced toner concentration by preventing a partial tribo reduction, thereby eliminating a partial decrease in image density and increasing the total amount of toner in the developing device. It is to reduce temporary concentration fluctuations that occur rarely.

[0026]

SUMMARY OF THE INVENTION The present invention is a developing device having the following configuration.

(1) A developer container accommodating a developer comprising a toner and a carrier, a developing member for applying the developer in the developer container to a member to be developed, and a developer container extending in the longitudinal direction of the developing member. A partition member that is divided into two substantially parallel chambers, and a chamber on the developing member side of the two chambers is a second developer chamber, and a chamber on the opposite side of the second developer chamber from the developing member side is defined as a second developer chamber. When the first developer chamber is used, first developer stirring / transfer means for stirring / transferring the developer in the first developer chamber in one direction along the length of the chamber, and developer in the second developer chamber. Along the length of the chamber
A second developer agitating / transporting means for agitating / transferring the developer in a direction opposite to the developer transporting direction by the developer agitating / transporting means, and a downstream side of the first developer chamber in the developer transporting direction and a second developer chamber. A first communication path provided between the upstream side of the developer transfer direction and a second communication path provided between the downstream side of the second developer chamber in the developer transfer direction and the upstream side of the first developer chamber in the developer transfer direction; A developing device having a communication passage for circulating and transferring the developer in the developer container through a first developer chamber, a first communication passage, a second developer chamber, and a second communication passage; A toner replenishing port for replenishing toner to the developer, and at least one agitating / transporting developer.
A developing device comprising: at least one third developer stirring / transfer means; and wherein the second communication path is disposed in a region outside a developing member end face in a longitudinal direction of the developing member.

(2) The third developer stirring / transporting means is disposed at a position substantially horizontal to the first and second developer stirring / transporting means in the side sectional direction. The developing device according to (1).

(3) The third developer stirring / transporting means is disposed below the first and second developer stirring / transporting means in the side sectional direction. Developing device.

(4) The developing device according to any one of (1) to (3), wherein the developing member is a developing sleeve.

(5) The developing device according to any one of (1) to (4), wherein the developer stirring / transporting means is a rotary screw shaft.

<Operation> a) That is, similarly to the conventional apparatus, the toner concentration of the developer in the developing container is consumed for developing the latent image on the developing member side, and decreases with the consumption. When the toner concentration detected by the means for detecting the toner concentration of the developer in the developing container drops to an allowable lower limit, the toner is supplied from the toner replenishing section into the developer container of the developing device.

In this case, according to the present invention, as described above, a toner supply port for supplying toner to the developer and at least one third supply port for stirring and transferring the developer are provided in the second communication path.
The toner newly replenished in the portion of the second communication path is developed by the third developer stirring / transporting means before entering the first developer chamber. The developer in the apparatus is sufficiently agitated and enters the first developer chamber, and further transported while being agitated by the first developer agitating / transferring means in the first developer chamber, and is transferred from the first communication path to the second developer chamber. By entering the developer chamber, the toner is sufficiently stirred by the time the toner enters the second developer chamber, the toner concentration is made uniform, the tribo increases, and the image density unevenness and image quality as in the case of insufficient stirring are increased. Concentration reduction is prevented.

B) Since the second communication passage provided with the third developer stirring / transporting means is disposed outside the developing member end face in the longitudinal direction of the developing member, the second communication passage is provided. It is possible to increase the volume of the portion in the longitudinal direction, to linearize the flow of the developer in contact with the end of the developing member, to prevent stagnation, and to eliminate uneven image density due to a partial decrease in toner density. .

C) The total amount of the developer in the developing device is increased by expanding the volume of the second communication path provided with the third developer stirring / transfer means in an arbitrary direction. It is possible to reduce unevenness in image density due to a temporary or partial increase in the toner density of the developer at the time of toner supply as described above.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIG. 1) FIG. 1A is a cross-sectional side view of a developing device according to a first embodiment.
(B) is a vertical cross-sectional view. Constituent members and portions common to the developing device of FIG. 3 described above are denoted by the same reference numerals, and description thereof will not be repeated.

Reference numeral 13a denotes a toner supply port disposed above the second communication path 12, and reference numeral 15 denotes third developer stirring / transfer means disposed in the second communication path 12. The third developer stirring / transporting means in the present example is a rotary screw shaft like the first and second developer stirring / transporting means 9 and 10, and the front side wall 5 of the developer container 2 and the partition member The first and second developer agitating / transporting means 9 and 10 are arranged so as to be freely rotatable between the first and second end portions 6 and 6. The screw shaft as the third developer stirring / transporting means is driven to rotate at a predetermined rotation speed in the direction of the arrow.

The third developer stirring / transfer means 1
The portion of the second communication path 12 where the reference numeral 5 is disposed is disposed outside the developing sleeve end face in the longitudinal direction of the developing sleeve.

As described above, the toner supply port 13a for supplying toner to the developer and the third developer stirring / transfer means 15 for stirring / transferring the developer are provided in the second communication path 12 portion. As a result, the toner newly supplied to the second communication path 12 is stirred with the developer in the developing device by the third developer stirring / transfer means 9 before entering the first developer chamber 7. In the initial stage of the stirring / transferring process, the toner is sufficiently stirred and mixed into the first developer chamber 7, and is further transported in the first developer chamber 7 while being agitated by the first developer stirring / transferring means 9. By entering the second developer chamber 8 from the first communication path 11
The toner density is sufficiently agitated by the time the toner enters the second developer chamber 8 to make the toner density uniform, and the amount of tribo is increased, thereby preventing image density unevenness and image density reduction due to insufficient agitation. You.

Further, since the second communication passage 12 provided with the third developer stirring / transporting means 15 is disposed outside the developing roller end face in the longitudinal direction of the developing roller, the second communication passage is provided. The volume of 12 parts can be expanded in the longitudinal direction, the flow of the developer in contact with the developing roller end 3a is linearized to eliminate the stagnation, and the developer containing the toner is stably supplied to the entire developing sleeve. This makes it possible to eliminate uneven image density due to a partial decrease in toner density.

The total amount of the developer in the developing device can be increased by expanding the volume of the second communication path 12 provided with the third developer stirring / transporting means 15 in an arbitrary direction. This reduces unevenness in image density due to a temporary or partial increase in the toner density of the developer during toner replenishment.

<Second Embodiment> (FIG. 2) FIG. 2A is a cross-sectional side view of a developing device according to a second embodiment.
(B) is a vertical cross-sectional view.

The developing device of this embodiment is different from the developing device of the first embodiment in that the third developer agitating / transporting means 15 of the second communication path 12 is connected to the first developing means in the side sectional direction of the developing device. This is provided below the second developer stirring / transfer means 9 and 10. Other device configurations are the same as those of the developing device of the first embodiment.

The developing device of the present embodiment has the same operation and effect as the developing device of the first embodiment, and further has a larger capacity of the second communication passage 12 than the developing device of the first embodiment. As a result, the total amount of the developer in the developing device can be increased, and there is an effect of further reducing unevenness in image density due to a temporary or partial increase in the toner density of the developer during toner replenishment.

[0045]

As described above, according to the present invention, in this type of developing apparatus, insufficient stirring of the developer can be solved.
By sufficiently agitating the toner and the carrier in the initial stage of the agitation and transfer of the developer, it is possible to provide a larger tribo, and it is possible to eliminate a decrease in image density and unevenness.

Further, by preventing insufficient stirring of the developer agitated and transferred in the developing device due to stagnation near the developing member, it is possible to prevent a partial tribo of toner in the developer from lowering. In addition to eliminating the partial decrease in image density and increasing the total amount of toner in the developing device, temporary density fluctuations that occur rarely when replenishing toner to a developer whose toner density has decreased can be reduced. It became possible to reduce. Therefore, it is possible to impart sufficient tribo to the toner contained in the developer, and it is possible to obtain a good image by reducing the density or unevenness of the image.

Further, by preventing the developer from staying in the vicinity of the developing member, and by reducing the influence of the increase or decrease of the toner content in the developer, it is possible to reduce the decrease or unevenness of the toner in the developer, It has become possible to obtain an image with a uniform density.

[Brief description of the drawings]

FIG. 1A is a cross-sectional side view of a developing device according to a first embodiment, and FIG.

FIG. 2A is a cross-sectional side view of a developing device according to a second embodiment, and FIG.

FIG. 3A is a cross-sectional side view of a conventional developing device.
(B) is a longitudinal plan view

[Explanation of symbols]

REFERENCE SIGNS LIST 100 photoconductor (development member) 1 developing device 2 developer container 3 developing roller 6 partition member 7.8 first and second developer chambers 9, 10, 15 first, second, and third developer stirring Transfer means (rotary screw shaft) 11 and 12 First and second communication paths 13 Hopper 13a for supplying toner 13a Toner supply port

Claims (5)

[Claims] A developer container for storing a developer including a toner and a carrier; a developing member for applying the developer in the developer container to a member to be developed; A partition member that is divided into two parallel chambers, and a chamber on the developing member side of the two chambers is a second developer chamber, and a chamber on the opposite side of the second developer chamber from the developing member side is a second developer chamber. When one developer chamber is provided, a first developer stirring / transfer unit for stirring / transferring the developer in the first developer chamber in one direction along the length of the chamber; and a developer in the second developer chamber. A second developer agitating / transporting means for agitating / transferring along a length of the chamber in a direction opposite to a developer transporting direction by the first developer agitating / transporting means;
A first communication path provided between the downstream side of the developer chamber in the developer transport direction and the upstream side of the second developer chamber in the developer transport direction; a first communication path downstream of the second developer chamber in the developer transport direction; A second communication path provided between the first developer chamber, the first communication path, the second developer chamber, and the second communication chamber; In a developing device that circulates and transports the toner in a passage, a toner supply port that supplies toner to the developer and at least one or more third developer agitators that agitate and transport the developer are provided in the second communication path. A developing device, wherein a transfer means is provided, and the second communication path is provided in a region outside an end surface of the developing member in a longitudinal direction of the developing member. 2. The apparatus according to claim 1, wherein the third developer stirring / transporting means is disposed substantially horizontally with the first and second developer stirring / transporting means in a side sectional direction. 3. The developing device according to claim 1. 3. The apparatus according to claim 1, wherein the third developer stirring / transporting means is disposed below the first and second developer stirring / transporting means in a side sectional direction. Developing device. 4. The developing device according to claim 1, wherein the developing member is a developing sleeve. 5. The developing device according to claim 1, wherein the developer stirring / transferring means is a rotary screw shaft.