Image forming apparatus

Abstract

To provide an image formation device that stables a discharge response to an amount of mixture of toner and carrier, prevents excessive discharge or excessive increase of the mixture thereof, and can stabilize the amount of mixture thereof within a developer tank under an environment variation, and T / D variation.SOLUTION: An image formation device comprises: a first agitation conveyance member 19 and second agitation conveyance member 20 that convey developer stored in a first developer agitation conveyance chamber and second developer agitation conveyance chamber while agitating the developer stored therein; a developer carrier that carries the developer agitated and conveyed by the second agitation conveyance member 20; a first communication part 21 and second communication part 22 that cause the first developer agitation conveyance chamber and second developer agitation conveyance chamber to communicate on one and other end sides of a developer tank; and a trickle discharge member 25 that is provided in the developer tank, and discharges the developer outside of the developer tank. The image formation device has the trickle discharge member 25 that is further on a downstream side of the first communication part 21 on the downstream side of the first agitation conveyance member 19, and both spiral blades of the first agitation conveyance member 19 and second agitation conveyance member 20 are fully lacking in the first communication part 21.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] This disclosure relates to an image forming apparatus having a trickle type developing unit.

Background Art

[0002] In an image forming apparatus using a two-component developer containing dev (a mixture of toner and carrier), while the toner consumed by image formation is newly replenished as needed, the carrier remaining in the developing device deteriorates over time. In order to extend the life of the developing device regardless of this carrier deterioration, a trickle method has been proposed in which new carrier is replenished while the deteriorated carrier is discarded little by little. In the trickle method, initially, a form in which the developer is circulated using a two-axis screw (agitating member) arranged horizontally was adopted, and when the height of the liquid level of the developer in the developing device became a certain level or more, a liquid level overflow type in which the carrier is discharged from the trickle discharge part became the mainstream.

[0003] When the fluidity of the developer changes or the operating speed of the developing device changes, the balance between the discharge force for discharging the developer from the trickle discharge part and the discharge blocking force for blocking the discharge of the developer in the developing device is disrupted, so the amount of developer present in the developing device fluctuates. When the fluidity of the developer changes or the operating speed of the developing device changes, there is a problem that the amount of developer present in the developing device fluctuates because the balance between the discharge force for discharging the developer and the discharge blocking force for blocking the discharge of the developer in the developing device is disrupted.

[0004] In order to solve the above problems, it has been proposed to provide a reverse blade member having a spiral part wound in the opposite direction to the spiral part of the agitating member of the two-axis screw on the upstream side of the trickle discharge part.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, in the technology disclosed in Patent Document 1, although there is a reverse vane member downstream of the second screw of the two-screw system, the helical screws rotate opposite each other at the communication point between the second screw and the first screw, which causes the liquid level of the deve to fluctuate up and down, resulting in the problem of excessive deve being discharged.

[0007] This disclosure was made to resolve the above-mentioned problems and aims to provide an image forming apparatus that can stabilize the discharge response to the amount of developer, prevent excessive discharge or increase of developer, and stabilize the amount of developer in the developing tank under environmental fluctuations and T / D fluctuations. [Means for solving the problem]

[0008] The image forming apparatus according to this disclosure comprises a developing tank having a first developer stirring and conveying chamber and a second developer stirring and conveying chamber for containing a developer; a first stirring and conveying member and a second stirring and conveying member for conveying the developer contained in the first developer stirring and conveying chamber and the second developer stirring and conveying chamber in a predetermined conveying direction while stirring it; a first connecting section and a second connecting section for connecting the first developer stirring and conveying chamber and the second developer stirring and conveying chamber at one end and the other end of the developing tank; and a trickle discharge section provided in the developing tank for discharging the developer contained in the developing tank to the outside of the developing tank. The trickle discharge section is located downstream of the first connecting section downstream of the first stirring and conveying member, and the spiral blades of the first stirring and conveying member and the second stirring and conveying member at the first connecting section are shaped so as not to splash the developer up.

[0009] Preferably, a shape in which the spiral blades do not splash up the developer is one in which at least a portion of the spiral blades of the first stirring and conveying member and the second stirring and conveying member are missing.

[0010] More preferably, the first stirring and conveying member includes a trickle reverse winding section provided coaxially with the first stirring and conveying member on the first communication section side, and the helical blades of the first stirring and conveying member and the second stirring and conveying member, with at least a portion missing, are in contact with the trickle reverse winding section.

[0011] In one embodiment of the present disclosure, the shape that prevents the helical blades from splashing the developer is such that a portion of the helical blades of the first stirring and conveying member and the second stirring and conveying member are covered by a cylindrical tube.

[0012] Preferably, the outer circumference of the cylindrical tube is in contact with the outer circumference of the first stirring and conveying member and the second stirring and conveying member.

[0013] More preferably, the first stirring and conveying member includes a trickle reverse winding section provided coaxially with the first stirring and conveying member on the first communication section side, and the cylindrical tube is in contact with the trickle reverse winding section.

[0014] The first stirring and conveying member includes a trickle discharge member having helical blades provided coaxially with the first stirring and conveying member on the side of the first communication section, and the winding direction of the helical blades of the trickle discharge member may be the same as the winding direction of the first stirring and conveying member.

[0015] It is preferable that the first stirring and conveying member is located further away from the developer carrier than the second stirring and conveying member. [Effects of the Invention]

[0016] According to this disclosure, in a trickle developing tank having a twin-screw configuration consisting of a first stirring and conveying member and a second stirring and conveying member, the blade shapes of the opposing twin-screw configurations at the communication section (developing transfer section) located before the trickle reverse winding section on the downstream side of the stirring and conveying member in the developing discharge direction are configured to prevent the developing from being thrown up.

[0017] As a result, we can provide an image forming apparatus that can stabilize the discharge response to the amount of developer, prevent excessive discharge or increase of developer, and stabilize the amount of developer in the developing tank under environmental fluctuations and T / D fluctuations.

[0018] The above objects, other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments made with reference to the drawings.

Brief Description of the Drawings

[0019] [Figure 1] It is a perspective view showing a specific configuration of a developing unit having a trickle discharge portion. [Figure 2] In FIG. 1, it is a view in the direction of an arrow of a cross-sectional portion indicated by arrow 2-2. [Figure 3A] It is a side view showing the vicinity of the trickle discharge portion of an image forming apparatus according to the first embodiment of the present disclosure. [Figure 3B] It is a perspective view showing the vicinity of the trickle discharge portion of an image forming apparatus according to the first embodiment of the present disclosure. [Figure 4A] It is a side view showing the vicinity of the trickle discharge portion of an image forming apparatus according to a modified example of the first embodiment of the present disclosure. [Figure 4B] It is a perspective view showing the vicinity of the trickle discharge portion of an image forming apparatus according to a modified example of the first embodiment of the present disclosure. [Figure 5A] It is a side view showing the vicinity of the trickle discharge portion of an image forming apparatus according to a further modified example of the first embodiment of the present disclosure. [Figure 5B] It is a perspective view showing the vicinity of the trickle discharge portion of an image forming apparatus according to a further modified example of the first embodiment of the present disclosure. [Figure 6A] It is a side view showing the vicinity of the trickle discharge portion of an image forming apparatus according to the second embodiment of the present disclosure. [Figure 6B] It is a perspective side view showing the vicinity of the trickle discharge portion of an image forming apparatus according to the second embodiment of the present disclosure. [Figure 6C] In FIG. 6A, it is a perspective view of a portion indicated by arrow 6C-6C. [Figure 6D] In FIG. 6A, it is a perspective view of a portion indicated by arrow 6D-6D. [Figure 7] It is a view showing the developing liquid surface in the second embodiment. [Modes for carrying out the invention]

[0020] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. First, the shape of the vicinity of the trickle discharge portion of an image forming apparatus having a trickle discharge portion according to one embodiment of the present disclosure will be described.

[0021] First, the specific configuration of the image forming apparatus having a trickle discharge unit according to this disclosure will be described. Figure 1 is a perspective view showing the specific configuration of a developing unit 57 having such a trickle discharge unit, and Figure 2 is a view in the direction of the arrow in the cross-sectional portion indicated by arrow 2-2 in Figure 1. Referring to Figures 1 and 2, the developing unit 57 is shown with the front side being the R side (rear side or back) and the rear side being the F side (front side or front), with a toner supply port 23 provided on the R side, and a first developer stirring and transport chamber 15 and a second developer stirring and transport chamber 16 extending in parallel from the R side to the F side, separated by a partition wall 18. Here, the developing tank 17 is composed of the first developer stirring and transport chamber 15 and the second developer stirring and transport chamber 16.

[0022] The first developer agitation and transport chamber 15 houses the first agitation and transport member (first screw) 19, the second developer agitation and transport chamber 16 houses the second agitation and transport member (second screw) 20, and above the second agitation and transport member 20 is a developer carrier (developing roller) 14 arranged in parallel with the second agitation and transport member 20. To hold these members, a photoreceptor positioning section (shaft fitting section) 28 is provided for positioning the photoreceptor and developing unit 57 (not shown).

[0023] The first stirring and conveying member 19 conveys a material (not shown) from the R side to the F side, and the second stirring and conveying member 20 conveys a material (not shown) from the F side to the R side. In other words, the first stirring and conveying member 19 and the second stirring and conveying member 20 constitute a twin-screw configuration facing each other. Therefore, they may be referred to as twin-screw 19 and 20 below.

[0024] The first developer agitation and transport chamber 15 has a trickle discharge section (not shown) which is an extension of the first developer on the F side, and a trickle discharge member 25 is provided inside the trickle discharge section, with a developer trickle discharge port 27 provided on the lower side of its end.

[0025] The partition wall 18 has interconnected sections at its ends on the R side and F side. The interconnected section on the F side is called the first interconnected section 21, and the interconnected section on the R side is called the second interconnected section 22. Arrows indicate the direction of development flow at each of the interconnected sections 21 and 22. On the front side of the R side, opposing arrows indicate the rotation directions of the first stirring and conveying member 19 and the second stirring and conveying member 20.

[0026] Next, a first embodiment of the present disclosure will be described. In the first embodiment, an image forming apparatus is provided in which a first communication section 21 is provided downstream of a first stirring conveying member 19 in a first developer stirring conveying chamber 15, and a trickle discharge section 26 having a trickle discharge member 25 provided coaxially downstream of the first stirring conveying member 19 in the first communication section 21 is provided, wherein the shape of the helical blades of the first stirring conveying member 19 and the second stirring conveying member 20 in the first communication section 21 is such that the developer does not splash up. The shape of the helical blades of the first stirring conveying member 19 and the second stirring conveying member 20 will be described in detail below. [First Embodiment] In the first embodiment of this disclosure, the helical blades of the first stirring and conveying member 19 and the second stirring and conveying member 20 are at least partially missing at the first connecting portion 21.

[0027] Figure 3A is a side view showing the vicinity of the trickle discharge section 26 of an image forming apparatus according to a first embodiment of the present disclosure, and Figure 3B is a perspective view thereof. As shown in Figures 3A and 3B, the first stirring and conveying member 19 is provided with a trickle reverse winding section 24, which is coaxial with the first stirring and conveying member 19 and is an extension thereof, and a trickle discharge member 25, on the F side (see Figure 1) of the first communication section 21. The trickle discharge member 25 is housed in the trickle discharge section 26, which is its casing, and a trickle discharge section outlet 27 for discharging deve is provided at the lower part of the F-side tip of the trickle discharge section 26.

[0028] Referring to Figures 3A and 3B, in this embodiment, in the first connecting section 21, both the helical blades of the first stirring and conveying member 19 and the second stirring and conveying member 20 are removed (the parts enclosed by dotted lines in Figures 3A and 3B).

[0029] In other words, here, both helical blades of the opposing twin-screw 19 and 20 located just before the trickle reverse winding section 24 are cut. By cutting the helical blades, when the opposing twin-screw 19 and 20 rotate, the developer pushed by both screws no longer collide with each other. This prevents unevenness and splashing of the developer surface, stabilizes the developer discharge from the trickle discharge section, and prevents excessive developer discharge even when there is little developer.

[0030] Specifically, this spiral blade cut reduces splashing of the developer towards the trickle discharge section, stabilizes the developer's expansion, and ensures a stable discharge rate.

[0031] For example, even under conditions of high temperature and humidity, high T / D, or high depletion, the cutting of the screws of the first stirring and conveying member 19 and the second stirring and conveying member 20 reduces the amount of material pushed into the trickle discharge section and stabilizes the amount of material discharged, resulting in smoother depletion discharge and improved discharge response.

[0032] Next, a modified example of this embodiment will be described. Figures 4A and 4B correspond to Figures 3A and 3B, which show this modified example. Note that in Figures 4A and 4B, the trickle discharge section and the trickle discharge section outlet are not shown.

[0033] In this modified example, all the blades of the first stirring and conveying member 19 are cut off, while the blades of the second stirring and conveying member 20 are not cut (see the area enclosed by the dotted line in Figures 4A and 4B). In this case as well, almost the same effect as in the previous embodiment can be obtained.

[0034] Next, a further modification of this embodiment will be described. Figures 5A and 5B correspond to Figures 4A and 4B, which show this further modification. In this modification, the spiral blades of the first stirring and conveying member 19 and the second stirring and conveying member 20 are partially cut (see the areas enclosed by dotted lines in Figures 4A and 4B). In this case as well, substantially the same effect can be obtained.

[0035] As described above, in this embodiment, the image forming apparatus has a trickle discharge section further downstream of the first communication section downstream of the first stirring and conveying member, and at least a portion of the helical blades of the first stirring and conveying member and the second stirring and conveying member are missing at the first communication section.

[0036] As a result, when the two opposing screws in the first connecting section before the trickle reverse winding section rotate, the developer pushed by both screws does not collide with each other, and the liquid level in the first connecting section can be stabilized. In addition, the amount of developer pushed into the trickle discharge section 26 (see Figure 3A) is reduced, and the amount of developer is also stabilized, so the discharge of developer from the trickle discharge section outlet 27 (see Figure 3A) becomes smoother, and the discharge response is improved.

[0037] Furthermore, the amount of cutting done on each blade is not to cut the entire blade, but for example, to cut only one side, or to cut half of each blade (half the height of the blade). In this case, it is possible to maintain a certain level of feed force in the direction of conveying the material while reducing the material from bouncing up and the unevenness of the material surface.

[0038] Here, it is even better if the cut portion of this blade is in contact with the front end of the trickle reverse winding section 24, as shown in Figures 3A and 3B. This is because the unevenness and movement of the first connecting section 21 will have less impact on the trickle discharge section 26.

[0039] Furthermore, as shown in Figures 3A and 3B, the first developer agitation and transport chamber 15 houses the first agitation and transport member 19, the second developer agitation and transport chamber 16 houses the second agitation and transport member 20, and a developer carrier (developing roller) 14 is positioned on top of the second agitation and transport member 20 in parallel with the second agitation and transport member 20. In this way, because the trickle discharge section 26 (see Figure 3A), which is provided continuously with the first agitation and transport member 19, is separated from the developing roller 14, the trickle discharge section 26 (see Figure 3A) is less affected by the magnetic field of the developing roller 14 and the peeling developer, the developing liquid level in the first communication section 21 is stabilized, and the appropriate amount of developing liquid can be discharged. [Second Embodiment] Next, a second embodiment of the present disclosure will be described. In the second embodiment, the shape of the helical blades of the first stirring and conveying member and the second stirring and conveying member that prevents the developer from splashing up is such that a portion of the helical blades of the first stirring and conveying member and the second stirring and conveying member are covered with a cylindrical tube. That is, in this embodiment, the shape of the helical blades of the opposing twin-screws in the first connecting section before the trickle reverse winding section 24 located downstream in the developer discharge conveying direction is such that the developer does not splash up, and a cylindrical tube is installed on the outer circumference of the blades of the opposing twin-screws.

[0040] Figure 6A is a side view showing the vicinity of the trickle discharge section of the image forming apparatus in this embodiment; Figure 6B is a perspective view showing the vicinity of the trickle discharge section of the image forming apparatus according to this embodiment; Figure 6C is a perspective view of the portion indicated by arrow 6C-6C in Figure 6A; and Figure 6D is a perspective view of the portion indicated by arrow 6D-6D in Figure 6A.

[0041] Figure 6A corresponds to Figure 3A of the previous embodiment. In Figures 6B to 6D, the trickle discharge section and the trickle discharge outlet are omitted from the illustration.

[0042] Referring to Figures 6A to 6D, in this embodiment, cylindrical tubes 34a and 34b are installed around the outer circumference of the helical blades of the first stirring and conveying member 19 and the second stirring and conveying member 20, which are opposing twin-screws, in the first connecting section 21 (see the areas enclosed by dotted lines in Figures 6A and 6B). When the opposing twin-screws 19 and 20 of the first connecting section 21 before the trickle reverse winding section 24 rotate, the outer circumferences of their blades are covered by the cylindrical tubes 34a and 34b, preventing the deposits from colliding and stabilizing the liquid level in the first connecting section 21. This prevents excessive discharge of deposits, even when there are few deposits.

[0043] Furthermore, by matching the outer circumference of the cylindrical tubes 34a and 34b with the outer diameter of the first and second screws 19 and 20 (by making them in contact with the outer circumference of the cylindrical tubes 34a and 34b), the step difference between the first and second screws 19 and 20 and the cylindrical tubes 34a and 34b is eliminated, reducing unevenness and movement of the deve at the first connecting section 21, and maximizing the amount of deve passing through the inside of the cylindrical tubes 34a and 34b, allowing for stable transport of the deve.

[0044] Furthermore, by positioning the cylindrical tubes 34a and 34b in contact with the trickle reverse winding section 24, the unevenness and movement of the development in the connecting section have less impact on the trickle discharge section.

[0045] In this embodiment, for example, the shaft diameter of the conveying screw is 8 mm, the outer diameter of the cylinder and the conveying screw is 18 mm, the wall thickness of the cylinder is 1.0 mm, and the blade height inside the cylindrical part is 4.0 mm.

[0046] Figure 7 shows the developer liquid level 37 in this embodiment and illustrates the effects of this embodiment. Referring to Figure 5, the presence of the cylindrical tube 34 in contact with the trickle reverse winding section 24 reduces the impact on the trickle discharge section 26 due to irregularities and turbulence of the developer in the first communication section 21. Furthermore, since the maximum amount of developer inside the cylindrical tube 34 is determined by the inner diameter of the cylindrical tube 34, the amount of developer in front of the trickle reverse winding section 24 does not become excessively large even when the developer fluidity deteriorates, such as during high temperature and high humidity / T / D increase, thus preventing a decrease in discharge volume due to developer clogging in the trickle reverse winding section 24. As a result, even when fluidity deteriorates, the amount of developer in the developing tank does not increase rapidly and the developing tank does not become overloaded with developer.

[0047] This disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the embodiments described above are illustrative and should not be constrained. Any modifications or changes within the equivalent scope of the claims of this disclosure are within the scope of this disclosure. [Industrial applicability]

[0048] According to this disclosure, it is possible to provide an image forming apparatus that can stabilize the discharge response to the amount of developer, prevent excessive discharge or increase of developer, and stabilize the amount of developer in the developing tank under environmental fluctuations and T / D fluctuations, making it useful as an image forming apparatus. [Explanation of symbols]

[0049] 14. Developer carrier (developing roller) 15. First Developer Agitation and Conveying Chamber 16. Second Developer Agitation and Conveying Chamber 17 Developer tank 18 Partition Wall 19. First stirring and conveying member (first screw) 20. Second stirring and conveying member (second screw) 21 1st communication part 22 2nd communication part 23 Toner supply port 24 Trickle reverse winding section 25 Trickle discharge member 26 Trickle discharge section 27 Trickle discharge outlet 28. Photoreceptor positioning section (shaft fitting section) 34 cylindrical tubes 37 Developing liquid level 57 Developing Unit

Claims

1. A developing tank having a first developer stirring and conveying chamber and a second developer stirring and conveying chamber, and containing a developer, A first stirring and conveying member and a second stirring and conveying member that convey the developer contained in the first developer stirring and conveying chamber and the second developer stirring and conveying chamber in a predetermined conveying direction while stirring the developer, A first connecting section and a second connecting section are provided at one end and the other end of the developing tank, connecting the first developer stirring and conveying chamber and the second developer stirring and conveying chamber. An image forming apparatus comprising a trickle discharge unit provided in the developing tank for discharging the developer contained in the developing tank to the outside of the developing tank, The trickle discharge section is located further downstream of the first communication section on the downstream side of the first stirring and conveying member, In the first connecting section, a portion of the spiral blades of the first stirring and conveying member and the second stirring and conveying member are covered by a cylindrical tube. An image forming apparatus characterized by the following.

2. The image forming apparatus according to claim 1, wherein the outer circumference of the cylindrical tube is in contact with the outer circumference of the first stirring and conveying member and the second stirring and conveying member.

3. The first stirring and conveying member includes a trickle reverse winding section provided coaxially with the first stirring and conveying member on the side of the first communication section, The image forming apparatus according to claim 2, wherein the cylindrical tube is in contact with the trickle reverse winding portion.

4. The first stirring and conveying member includes a trickle discharge member having spiral blades provided coaxially with the first stirring and conveying member on the side of the first communication portion, The image forming apparatus according to claim 1, wherein the winding direction of the helical blades of the trickle discharge member is the same as the winding direction of the first stirring and conveying member.

5. A developer carrier having a developer that is stirred and conveyed by the second stirring and conveying member, The image forming apparatus according to claim 1, wherein the first stirring and conveying member is further away from the developer carrier than the second stirring and conveying member.

Images