JP2002258605A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable image over a long term by preventing the mark of a stirring member such as screw-shaped irregularity from appearing on the image in a developing device using a screw-like or paddle-like member for the purpose of carrying and stirring the developer. SOLUTION: This image forming device is provided with a 2nd regulating member 11 at a downstream position in a developer carrying direction by a 2nd screw 6 and at a more upstream position than a doctor 8, that is, between the 2nd screw 6 and the doctor 8. The screw-shaped mark formed on a developing sleeve 2 is eliminated by the 2nd regulating member 11, and the developer is made uniform. Appropriate development is always performed by regulating the developer to necessary height by the doctor 8 being a 1st regulating member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system, such as a printer using two-component development, a PPC, and a facsimile.

[0002]

2. Description of the Related Art A generally known two-component developing apparatus develops a latent image on a photoconductor at a first pole called a main pole, and then develops the latent image on a developing sleeve. Pass through a plurality of magnetic poles formed in the magnetic field. During this process, the agent after development is removed (agent removal), a new agent is pumped (pumping), and the height is regulated to deliver the required amount of agent to the development area (agent height regulation). , And the process of transporting the agent to the developing region again is repeated. These development, running out of agent, pumping up,
Stable development with few abnormalities is achieved by optimizing the direction, strength, and shape of the magnetic poles in accordance with the diameter and linear velocity of the developing sleeve so that height regulation can be properly performed.

FIG. 1 is a sectional view showing an example of an image forming section of this type of image forming apparatus. The developing sleeve 2 develops the latent image on the photoreceptor 1 charged and exposed by means not shown. The paper conveyed by the pair of paper feed conveyance rollers 3 at the lower right in the figure is transferred with a latent image on the photoreceptor 1 by the transfer roller 4 and is sent to a fixing unit (not shown) located at the upper part in the figure. The image is fixed.

The photoreceptor 1 and the developing sleeve 2 rotate in the directions indicated by arrows in the figure, and screws 5 and 6 for conveying toner are provided below the developing sleeve 2. The first screw 5 is provided at a position shifted to the left in the figure from the developing sleeve 2, and the second screw 6 is provided at a position slightly shifted to the left in the figure from the developing sleeve 2. Second
The first screw 5 is configured to transport the developer from the back (left side in the figure) to the front (right side in the figure), and the first screw 5 is configured to transport the developer from the front to the back. The arrangement of these screws 5, 6 is shown in FIG. In the figure, reference numeral 7 denotes a toner sensor.

FIG. 3 is a diagram showing a general arrangement of magnets on the developing sleeve 2. After the developer developed at the main pole (P1) is transported to the pole P2, the portion having a particularly weak magnetic force (P
In step 3), the developing sleeve 2 is peeled off. The second screw 2 is provided below the developing sleeve 2 as described above, and transports the developer from the back to the front on the developing sleeve 2.
The developer is pumped and lifted by the pole (P4), and the pole P5,
During conveyance at P6, only an appropriate amount of developer can be supplied to the pole P1 by the doctor 8, which is a member for regulating the height of the developer. Although the illustrated example has a six-pole arrangement, this arrangement differs depending on the diameter of the developing sleeve, the linear velocity, the developing configuration, and the like.

That is, in order to attach the developer to the developing sleeve 2, it is not always possible to draw a new uniform agent only by the magnetic force of the pumping. Therefore, a member for supplying the developer to the developing sleeve 2 is installed in the vicinity. What you do is common. Among them, a paddle-shaped member having a shape such as a rotating elliptical plate for supplying the developer to the developing sleeve 2 and a screw-shaped or elliptical plate in which the elliptical plate swings as the shaft rotates are generally used. It is. In the case of a paddle-shaped member, the supply of the agent to the developing sleeve goes smoothly, but the agent does not easily move in the axial direction of the developing sleeve, and density unevenness is likely to occur. Conversely, in the case of a screw-shaped member, there is a merit that the agent concentration in the developing unit tends to be uniform, but since the power for supplying the developer to the developing sleeve is weak, it is necessary to install the member near the developing sleeve. is there. For this reason, a screw mark easily occurs on the image.

FIG. 4 shows the state of the developer immediately after being pumped by the screw. Since the screws 5 and 6 are located in a portion where the pumping force is strong, screw marks 10 are observed in the developer 9 supplied to the developing sleeve 2. This pattern may appear in the image depending on the state of the developer, the environment, and the like.

Accordingly, the present invention provides a two-component developing apparatus using a screw-shaped or paddle-shaped member for transporting and stirring the developer. To prevent them from appearing in
An object is to obtain a stable image for a long time.

[0009]

According to a first aspect of the present invention, there is provided an image forming apparatus that uses two-component development and conveys the developer in an axial direction of a developing sleeve. In the image forming apparatus using the device, the developer pumped up between the developer regulating member for regulating the height of the developer on the developing sleeve and the stirring and conveying member used for conveying the developer is transferred to the developing sleeve. A second regulating member made of a resin or a metal material pressed against the second member.

According to a second aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the second regulating member has a two-layer structure, and each of the second regulating members has a rigidity made of resin or metal. And a highly elastic support member and a highly elastic strainable member.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the deflectable member is arranged in a downstream direction with respect to a flow of the developer conveyed to the developing sleeve. In addition, it is characterized in that it protrudes from the support member.

According to a fourth aspect of the present invention, in the image forming apparatus of the second or third aspect, the second regulating member has a wedge having an upstream end as a vertex in a direction in which the developer flows. It is characterized by having a shape.

According to a fifth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the second to fourth aspects, the flow of the developer from the upstream end of the support member to the flow of the developer. T1 <T2, where T1 is the distance to the developing sleeve and T2 is the distance from the downstream end.

According to a sixth aspect of the present invention, in order to achieve the above object, in the image forming apparatus of any one of the first to fifth aspects, a gap between the developing sleeve and the second regulating member is A gap between the developer regulating member and the developing sleeve is larger than a gap between the developing sleeve and the stirring and conveying member.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the following, portions common to the related art are denoted by the same reference numerals, and redundant description is omitted. FIG. 5 is a cross-sectional view of an image forming unit in one embodiment of the image device according to the present invention, and FIG. 6 is an enlarged cross-sectional view of the same. A second regulating member 11 is provided at a position downstream of the second screw 6 in the developer conveyance direction and upstream of the doctor 8, that is, between the second screw 6 and the doctor 8. As a result, the screw-shaped mark formed on the developing sleeve 2 is eliminated, and the developer becomes uniform after passing through the regulating member. By regulating this to a required height by the doctor 8, proper development can always be performed.

If the second regulating member 11 close to the developing sleeve 2 is made of a magnetic material, the magnetic field lines of the developing sleeve 2 change and the magnetic material is magnetized, so that the desired developing characteristics cannot be obtained. However, there is a possibility that abnormalities such as toner scattering may occur. Therefore, such a problem can be avoided by making the regulating member 11 non-magnetic.

Although the regulating member 11 can obtain the effect of preventing abnormal images even with a rigid body, if a rigid body is used, if the tip has irregularities, it will adversely cause an abnormal image. With this configuration, even if the tip has some irregularities, the agent is leveled by elasticity, so that an abnormal image is less likely to occur. In addition, manufacturing accuracy can be reduced, leading to cost reduction.

A gap A between the regulating member 11 and the developing sleeve 2
Is preferably larger than the gap X between the doctor 8 and the developing sleeve 2. As a result, the height of the developer 8 is regulated by the doctor 8 in which unevenness is reduced and uniformized in advance.
Appropriate development can be performed. Further, if the gap Y between the second screw 6 and the developing sleeve 2 is smaller than the gap between the regulating member 11 and the developing sleeve 2, the effect of uniformizing the unevenness of the developer formed on the developing sleeve 2 is sufficient. I can't get it. FIG. 6 illustrates a state in which the uneven developer (gap Y) is leveled by the regulating member 11 and the height thereof is regulated by the doctor 8 (the portion extending from the gap A to X) by the second screw 6 being pumped up. Show. The height is regulated by the doctor 8,
The scraped-off developer flows back to the agitating section by the screws 5 and 6 through the outside of the regulating member 11 as shown by an arrow e in the drawing.

Therefore, the gap X between the regulating member 11 and the developing sleeve 2, the gap X between the doctor 8 and the developing sleeve 2, and the gap Y between the second screw 6 and the developing sleeve 2, X <A <Y. There is a relationship.

FIG. 7 is a schematic diagram of an abnormal image in which screw traces appear. White stripes w appear on the image in a pitch shape. On the other hand, FIG. 8 shows an example of an image when the regulating member 11 of the present embodiment is partially used in the entire length of the developing sleeve 2. The white stripe w is not generated only in the portion to which the present embodiment is applied, that is, only in the portion Z corresponding to the portion where the regulating member 11 is provided.

FIG. 9 is an enlarged sectional view of an image forming unit in an embodiment of the image apparatus according to the present invention. The regulating member 21 of the present embodiment has a two-layer structure, in which a thin metal plate or a supporting member 22 made of resin, rubber, or the like, and a thin metal plate, or a deformable member 23 made of resin, rubber, or the like are bonded to each other. It is composed. The bonding means may be an adhesive, a double-sided tape, a sandwich, or the like. That is, in the present embodiment, since the regulating member 11 is configured by a single member in the previous embodiment,
This solves the problem that in order to obtain the optimum effect, it is necessary to search for various elastic members and select an appropriate elastic material.

The downstream end of the deformable member 23 is held in a fixed positional relationship with respect to the developing sleeve 2 with respect to the supporting member 21. The deformable member 23 protrudes to the downstream side, and is configured so that its elasticity can be effectively used. Further, by configuring the deformable member 23 to be located closer to the developing sleeve 2 than the support member 22, the developing sleeve 2 rotates and the developer is conveyed, and the deformable member 2
Even when the pressure of the developer is applied to 3, both members 22 and 23 are hardly peeled off.

Further, by devising the downstream shape of the support member 22 in the developer transport direction, it is possible to provide a configuration in which the flow of the developer in the developing unit is hardly obstructed. If the downstream end of the support member 22 is nearly horizontal, a part of the developer may stay on the support member 22 for a long time in some cases, and suddenly move to the developing sleeve 2 after the characteristics have changed with other developers. Could be supplied. Then, an abnormal image may be generated. Therefore, in the configuration of the present embodiment, a desired effect can be obtained by suppressing such side effects by forming a wedge shape.

In the present embodiment, the distance between the end of the regulating member 21 and the developing sleeve 2 is such that the distance T1 between the downstream end of the support member 22 and the distance T2 between the upstream end is T1 <.
It is configured to be T2. With this configuration, the developer attracted onto the developing sleeve 2 by the magnetic force is pressed while passing between the deformable member 23 and the developing sleeve 2 to increase the density. Further near the downstream end, the deformable member 23 bends due to the pressure of the developer, and the density of the developer is further increased by passing the developer therebetween, so that a partial density difference of the developer can be canceled.

For example, if the magnet of the developing sleeve 2 is 6
The distance Y between the developing sleeve 2 and the second screw 6 is 5 mm, and the distance X between the doctor 8 and the developing sleeve 2 is
0.35 mm, interval T1 between regulating member 21 and developing sleeve 2 = 3.0 mm, T2 = 6 mm, toner concentration of developer 4.5 wt%, linear speed of photoconductor 1 100 mm / s, linear speed of photoconductor 1 And the linear speed ratio of the developing sleeve 2 to the developing screw 2 is 1: 2.4, and the rotational speed ratio of the developing sleeve 2 to the second screw 6 is 16:
15. The thickness of the support member 22 = 2 mm, the material is ABS (acrylonitrile-butadiene-styrene resin), the thickness of the strainable member 23 is 0.3 mm, the material is PET, and the angle of the wedge-shaped portion is 45 degrees. The deformable member 23 was adhered with a double-sided tape, and the support member 22 was extended in the longitudinal direction of the developing sleeve 2 in parallel with the developing sleeve 2 and joined to a developing unit (not shown). I got

[0026]

As described above, the image forming apparatus according to the first aspect of the present invention has a structure in which the height of the developer is regulated upstream of the developer regulating member with respect to the rotation direction of the developing sleeve. By disposing the second regulating member downstream of the stirring and conveying member, the developer on the developing sleeve that has been pumped is evenly leveled before its height is regulated by the developer regulating member. Has the effect of preventing the developer unevenness from appearing on the image.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising:
As described above, by configuring the second regulating member with the support member and the deformable member, in addition to the above-described common effects,
There is an effect that the rigidity required for the second regulating member and an effective leveling action can be easily achieved at the same time.

According to a third aspect of the present invention, there is provided an image forming apparatus comprising:
As described above, in addition to the common effect, more effective development can be achieved by projecting the deformable member from the support member in the downstream direction with respect to the flow of the developer conveyed to the developing sleeve. There is an effect that a leveling action of the agent can be obtained.

An image forming apparatus according to a fourth aspect of the present invention comprises:
As described above, since the upstream end has a wedge shape in the direction in which the developer flows, in addition to the above-described common effect, by appropriately setting the distance between the member and the sleeve,
There is an effect that the sleeve can be leveled within a range that does not affect the height regulating member.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
As described above, the distance from the upstream end of the support member to the developing sleeve is T for the flow of the developer.
1. By setting the distance from the downstream end to T2 and T1 <T2, the overall arrangement of the second regulating member is configured such that the upstream side is wide and the downstream side is narrow, so that the developer is added to the above-described common effects. Has an effect that the developer can be effectively leveled as the density of the developer is conveyed.

An image forming apparatus according to a sixth aspect of the present invention comprises:
As described above, the gap between the developing sleeve and the second regulating member is larger than the gap between the developer regulating member and the developing sleeve, and smaller than the gap between the developing sleeve and the stirring and conveying member. In addition to the above-described common effects, the developer regulating member is configured to regulate the height of the developer in which unevenness is reduced in advance and uniform, so that proper development can be performed, and the uniformity of the developer can be further uniformized. The effect that it can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an image forming unit of an image forming apparatus.

FIG. 2 is a perspective view showing an arrangement of screws of the apparatus of FIG.

FIG. 3 is a diagram illustrating a magnetic pole arrangement of a general developing sleeve.

FIG. 4 is a front view showing a state of a developer on a developing sleeve.

FIG. 5 is a cross-sectional view of an image forming unit in an embodiment of the image device according to the present invention.

FIG. 6 is an enlarged sectional view of the same.

FIG. 7 is a schematic diagram of an abnormal image in which screw traces appear.

FIG. 8 is a schematic view of an image in which a screw mark does not appear by applying the present embodiment to a part.

FIG. 9 is an enlarged cross-sectional view of an image forming unit in an embodiment of the image device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing sleeve 3 Paper feed roller pair 4 Transfer roller 5, 6 Screw for toner conveyance 7 Toner sensor 8 Doctor 9 Developer 10 Screw mark 11, 21 Second regulating member 22 Support member 23 Strainable member

Claims (6)

[Claims] 1. An image forming apparatus using two-component developing and using a developing device that conveys the developer in the axial direction of a developing sleeve, wherein a developer regulating member that regulates the height of the developer on the developing sleeve is provided. An image forming apparatus comprising: a second regulating member made of a resin or a metal material for pressing the pumped developer against the developing sleeve between the developer and the stirring / transporting member used for transporting the developer. . 2. The image forming apparatus according to claim 1, wherein the second restricting member has a two-layer structure, and each of the second restricting member includes a highly rigid support member made of resin or metal and a highly elastic strainable member. An image forming apparatus comprising: 3. The image forming apparatus according to claim 2, wherein the deformable member projects from the support member in a downstream direction with respect to a flow of the developer conveyed to the developing sleeve. apparatus. 4. The image forming apparatus according to claim 2, wherein the second regulating member has a wedge shape with an upstream end as an apex in a direction in which the developer flows. 5. The image forming apparatus according to claim 2, wherein a distance from an upstream end of said support member to said developing sleeve is T1, and a distance from a downstream end is T2. An image forming apparatus, wherein T1 <T2. 6. The image forming apparatus according to claim 1, wherein a gap between the developing sleeve and the second regulating member is larger than a gap between the developer regulating member and the developing sleeve. An image forming apparatus, which is large and smaller than a gap between the developing sleeve and the stirring and conveying member.