JPH0990751A - Scraper device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an edge surely abut a developing roller, and stably peel a toner by providing a scraper which is made of a plate-like elastic body and is equipped with a base end portion, a tip edge elastically abutting the surface of a cylinder body, and a bent portion of a specific shape. SOLUTION: A scraper 31 made of a sheet-like elastic body is a rectangular sheet made of metal such as steel or the like, or a resin and the like, is equipped with specific elasticity, is parallel to a developing roller 13 in the lengthwise direction thereof, and a base end portion 32 is fastened to the low end portion of a partition wall 19 between a toner tank 17 and a roller case. An edge 33 which is the corner portion of the tip end low side of the scraper 31 abuts the surface of the developing roller 13. Between the base end portion 32 and the edge 33 and on the edge 33 side than the central portion thereof, a bent portion 34 protruding toward an anti-developing roller 13 side from a plane S linking the base end portion 32 and the edge 33. The bent portion 34 is bent with a proper angle, and its linear fold 34a extends along the lengthwise direction of the scraper 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scraper device suitable for removing and removing unnecessary substances adhering to the surface of a rotating cylinder from the surface. Examples of the cylindrical body include a developing roller of a developing device incorporated in an image forming apparatus using an electrophotographic process such as a copying machine or a printer, or a photosensitive drum.

[0002]

2. Description of the Related Art The developing device is an image forming device utilizing an electrophotographic process for visualizing an image portion (electrostatic latent image) formed on a surface of an image bearing member such as a charged photosensitive drum. Is. This developing device is classified into a dry developing type using powder toner and a liquid developing type using a developing solution in which toner is dispersed in a liquid. The dry developing method is classified into a one-component developing method using only toner as a developer and a two-component developing method using toner and a carrier. Among them, it is generally known that particularly in the one-component developing method, an image defect called a ghost in which an image density difference appears appears.

In the one-component developing method, a thin charged toner layer is formed on the surface of a developing roller provided in the vicinity of the image carrier, and the toner is deposited on the surface of the image carrier while rotating the developing roller. This is a developing method. Since the toner layer is extremely thin, almost all the toner corresponding to the image portion of the image bearing member disappears when it is subjected to development, while the toner of the non-corresponding portion remains as it is. Boundaries clearly occur. Toner is newly supplied to the non-corresponding portion until the next development, but the unevenness of the thickness remains as a history in the toner layer at that time, and the ghost is caused thereby.

In order to prevent this ghost, it is considered effective to remove the history by peeling and removing the toner that has not been used for development after the development, from the surface of the developing roller. As shown in FIG. 7, the device for peeling off the toner causes the scraper 3 made of a plate-like elastic body supported by the supporting member 2 to abut against the surface of the developing roller 1 rotating in the direction of arrow A, as shown in FIG. A relatively simple structure in which the toner T is peeled off is conventionally proposed. In the case of the device of FIG. 7, the scraper 3
The toner T peeled off from the surface of the developing roller 1 by passing over the scraper 3 and returning holes 2 formed in the supporting member 2.
After passing through a, it is returned to a toner tank (not shown).

According to such an apparatus, since a new toner is attached after the toner layer on the surface of the developing roller is peeled off, the history generated in the toner layer by the previous development is eliminated. As a result, there is no difference in the thickness of the toner layer, and good development is performed without ghost.

[0006]

In the apparatus as described above, it is important that the lower corner portion of the scraper 3, that is, the edge 3a is brought into contact with the surface of the developing roller 1 at an appropriate pressure. To do so, as shown in FIG.
Set angle θ of scraper 2 with respect to developing roller 1
1 and the working angle θ2 at the portion where the scraper 2 actually contacts the developing roller 1 are factors that influence the peeling ability. The set angle θ1 is an angle formed by the scraper 3 in a straight state assuming that the developing roller 1 is not present and a tangent line of the scraper 3 at the contact point with the developing roller 1. The working angle θ2 is an angle formed by a contact point when the scraper 3 is curved and actually contacts the developing roller 1, and a tangent line at the contact point. In principle, if the set angle θ1 is large and the working angle θ2 is also large, the edge 3a contacts the surface of the developing roller.

However, as shown in FIG. 7, when the set angle θ1 is increased, it is difficult for the toner T to climb over the scraper 3, the fluidity is deteriorated, and the toner T stays on the scraper 3. When the toner T is stagnant, it is not conveyed to the toner tank, and conversely overflows to the developing roller 1 side. In this case, the toner T may drop off on the surface of the image carrier, resulting in a remarkable defect in image quality.

When the set angle θ1 is large,
As indicated by the chain double-dashed line in FIG. 7, the scraper 3 is apt to be so-called “blip” as the developing roller 1 rotates. When the scraper 3 is turned over in this way, the peeling ability is lost at all. Therefore, it becomes necessary to reduce the set angle θ1 to the extent that this turning is not generated.

However, as shown in FIG. 8, if the set angle θ1 is too small, the tip of the scraper 3 floats and the flat lower surface of the scraper 3 is not the edge 3a.
It is apt to be rubbed on the surface of the so-called "belly". In this case, the working angle θ2 is 0
It becomes ゜. This bumping also occurs due to the balance with the length of the scraper 3. In this state, not only the toner layer cannot be separated from the developing roller 1, but also the toner is pressed against the surface of the developing roller 1. Then
The toner T sticks to the surface of the developing roller 1 to cause so-called filming, and as a result, large defects such as white spots occur in the image.

As described above, the scraper 3 is required to make a delicate and difficult adjustment of the set angle θ1 and the working angle θ2. In addition to this, the scraper 3 should be brought into uniform contact with the surface of the developing roller 1 in the axial direction thereof. Is important.
That is, if the scraper 3 is not in contact with the entire surface of the developing roller 1, the toner T in the non-contacting portion is naturally not peeled off. This problem occurs when the scraper 3 has a dimensional error, a mounting error, a deformation, or the like, or when the developing roller 1 is bent. Specifically, as shown in FIG. 9A, there is a phenomenon such as “one-sided contact” where only one side is in contact, and as shown in FIG. 9B, “floating” due to the distortion of the intermediate portion. . If the toner T cannot be partly peeled due to such a problem, a ghost will occur as described above.

In view of this, Japanese Patent Application Laid-Open No. 59-24875 discloses a technique for correcting uneven contact of a long plate-shaped member in the longitudinal direction. According to the publication, when the cleaning blade for removing the toner remaining on the photosensitive drum is supported by the supporting member, the supporting member has a shape divided in the longitudinal direction. With such a configuration, the supporting member is deformed as a whole, and the cleaning blade can follow the deformation and contact the photosensitive drum uniformly.

However, according to such a structure, it is assumed that the cleaning blade cannot completely follow the deformation of the supporting member depending on the rigidity of the cleaning blade, and the toner remains. Further, if the flexibility of the cleaning blade is improved in order to increase the followability, there is a concern that the contact pressure with the photosensitive drum becomes insufficient and the peeling ability becomes insufficient.

The present invention has been made in view of the above circumstances, and provides a scraper device in which the edge of the scraper is brought into proper contact with the surface of the developing roller to exhibit a stable toner peeling ability. It is an object.

[0014]

The scraper device of the present invention has been made to achieve the above object, and comprises a scraper made of a plate-like elastic body and a support member for supporting the scraper. Includes a base end portion supported by the support member, and a front end edge that faces the surface of the cylindrical body in the rotational direction thereof and elastically abuts, and further, the base end portion and the front end edge. A bent portion protruding from the plane connecting the base end portion and the front end edge to the side opposite to the cylindrical body is formed on the front end edge side with respect to the central portion between and.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. A. First Embodiment A-1. Configuration of First Embodiment (FIGS. 1 to 3) FIG. 1 shows a scraper device 10 according to a first embodiment of the present invention.
1 shows a developing device 11 of an image forming apparatus to which is applied. The developing device 11 includes a developing roller (cylindrical body) 13 arranged to face a photosensitive drum 12 which is an image carrier.
A toner layer forming section 14 for forming a toner layer on the surface of the developing roller 13, a toner supply section 15 for supplying toner (adhesion) T to the toner layer forming section 14, and an apparatus housing 16 for accommodating the entire apparatus. It consists of The device housing 16 includes a toner tank 17 that stores the toner T.
And a roller case 18 for accommodating the developing roller 13 are integrally formed. The toner tank 17 and the roller case 18 are partitioned by a partition wall (support member) 19 and are connected to each other by a toner supply port 20 opened in the partition wall 19.

The developing roller 13 is a magnet roller 21.
A sleeve 22 is attached to the surface of the roller case 18, is housed in the roller case 18, and is rotatably supported by the roller case 18. The developing roller 13 is the photosensitive drum 1.
The axis is parallel to 2 and is arranged so that a slight gap is formed between the surfaces of both. The developing roller 13 and the photosensitive drum 12 are each rotated in the direction of the arrow by a driving device (not shown).

The toner supply unit 15 is the toner tank 1
7 and an agitator 23 that supplies the toner T in the toner tank 17 to the toner layer forming unit 14. The agitator 23 is rotated in the direction of the arrow by a driving device (not shown), and the toner T is supplied from the toner supply port 20 to the toner layer forming unit 14 by the agitator 23.

The toner layer forming section 14 is a toner chamber 24 formed in the roller case 18 between the developing roller 13 and the partition wall 19 and a lower side of the developing roller 13 supported by the roller case 18. It is composed of a thinning blade 25 which is always in contact with the surface with an appropriate pressure. The toner T that has passed through the toner supply port 20 from the toner tank 17 is supplied to the toner chamber 24. The toner T in the toner chamber 24 adheres to the surface of the rotating developing roller 13 due to the magnetic force of the magnet roller 21, and then a toner layer having a constant layer pressure is formed by the thinning blade 25. It faces the drum 12.

The roller case 18 is open on the side of the photoconductor drum 12, and a part of the photoconductor drum 12 is inserted into the roller case 18 through the opening 18a. The toner T of the toner layer formed on the developing roller 13 and facing the photoconductor drum 12 moves to the image portion formed on the surface of the photoconductor drum 12 to visualize the electrostatic latent image, that is, is developed. .

Now, in the portion of the surface of the developing roller 13 after development, which does not correspond to the image portion of the photosensitive drum 12,
An undeveloped toner layer remains. This residual toner is
Before the new toner layer is formed in the toner layer forming unit 14, the scraper device 10 of the first embodiment peels and removes the toner layer.

As shown in FIGS. 2 and 3, the scraper device 10 includes a scraper 31 made of a plate-like elastic body.
And the partition wall 19 that supports the scraper 31. The scraper 31 is a rectangular thin plate (for example, a phosphor bronze plate having a thickness of about 0.1 mm) made of a metal such as steel or a material such as a resin, and has a predetermined elasticity. The 31 scraper has a longitudinal direction parallel to the developing roller 13, a base end portion 32 thereof is fixed to a lower end portion of the partition plate 19, and an edge (tip edge) 33 which is a lower corner portion of the tip end of the scraper 31 is a developing roller. It is in contact with the surface of 13. The edge 33 faces the surface of the developing roller 13 in the rotation direction thereof.

As shown in FIG. 3, the base end 32 and the edge 3
3, and a bent portion 34 projecting from the plane S connecting the base end portion 32 and the edge 33 to the side opposite to the developing roller 13 is formed on the edge 33 side with respect to the center portion thereof.
The bent portion 34 is bent at an appropriate angle, and a straight fold 34 a thereof extends along the longitudinal direction of the scraper 31. A plurality of return holes 19a are formed above the lower end of the partition plate 19 along the longitudinal direction of the scraper 31.

Further, as shown in FIG.
A large number of slits (flexibility imparting means) 35 extending from the edge 33 along the direction of the base end portion 32, that is, the width direction of the slit 33 are formed at equal intervals in the longitudinal direction. ing. These slits 35 are formed from the base end portion 32 to the front of the edge 33 via the bent portion 34. For example, the width dimension of the slits 35 is about 0.5 mm, and the pitch between the slits 35 is 2 m.
m is suitable for each. Also, the slit 3 at the tip
The remaining portion 31a where 5 is not formed has a length of about 1 mm.

As shown in FIG. 3, the base end portion 32 side of the bent portion 34 is curved toward the developing roller 13 side by elasticity, with the bent portion 34 as a boundary. The edge 33 side of the bent portion 34 remains flat with almost no elastic deformation. When the curved portion is the curved portion 36 and the flat portion is the flat plate portion 37, the flat plate portion 37 is fixed in a set state in which the base end portion 32 is fixed to the partition plate 19 and the edge 33 contacts the surface of the developing roller 13. It is substantially horizontal, and the curved portion 36 is gently inclined downward toward the partition wall 19. Due to this set state, the abutting portion on the surface of the developing roller 13 is the edge 33 which is the lower corner of the leading edge. The edge 33 is constantly in contact with the surface of the developing roller 13 by the elasticity of the curved portion 36 at a required pressure capable of separating the residual toner.

The set angle θ of the scraper 31
1 and the working angle θ2 are as shown in FIG. The set angle θ1 in this case is a line (corresponding to a curved portion in a natural state) extending along the base end portion 32 fixed to the partition plate 19 and a tangent line at the contact point of the line with the developing roller 13. It is an angle. Further, the working angle θ2 is determined by the flat plate portion 37 and the developing roller 13 of the edge 33.
Is an angle formed by the tangent line at the contact point with.

A-2. Operation and Effect of First Embodiment The operation of the scraper device 10 will be described together with the operation of the developing device 11. The toner T in the toner tank 17 is
The toner is supplied from the toner supply port 20 to the toner chamber 24 by the rotating agitator 23. The toner T adheres to the surface of the developing roller 13 that has entered the toner chamber 24 by the magnetic force of the magnet roller 21. Further, by passing through the thinning blade 25, a toner layer having a constant layer thickness is formed on the surface of the developing roller 13. When the toner layer faces the photoconductor drum 12, the toner T is transferred to the image portion formed on the surface of the photoconductor drum 12 and developed. On the surface of the developing roller 13 that has passed the developing area, the toner T that has not been used for developing remains.

The residual toner T is separated and removed by the edge 33 of the scraper 31 as the developing roller 13 rotates. The surface of the developing roller 13 after passing through the edge 33 has the history of the toner layer removed and the sleeve 2
2 is exposed. Therefore, the toner layer newly formed in the toner layer forming unit 14 is a toner layer having a favorable constant layer thickness without being affected by the previous toner layer. On the other hand, the peeled toner T flows along the inclination of the curved portion 36 of the scraper 31, passes through the return hole 19a, and the toner tank 1
It returns to 7 and circulates so that it may be used for development again.

According to the scraper device 10 described above, since the scraper 31 has the bent portion 34 protruding toward the side opposite to the developing roller 13, it is possible to secure a large working angle θ2 and reduce the set angle θ1. it can. That is, it is possible to implement the ideal setting state of the scraper, which cannot be set due to the conventional conflict.

According to the set state of the scraper 31,
Since a large working angle θ2 can be secured, the edge 33 accurately contacts the surface of the developing roller 13 and the toner peeling ability is sufficiently exhibited. Also, the conventional problem that the developing roller 13 is turned downward when the working angle θ2 is increased is eliminated by setting the set angle θ1 small. Furthermore, even if the set angle θ1 is small, the large working angle θ2 is secured as described above,
The phenomenon that the lower surface of the scraper 31 rubs against the surface of the developing roller 13 does not occur. That is, two contradictory set conditions are satisfied: a setting condition for reducing the set angle θ1 to prevent abdominal contact and a setting condition for increasing the working angle θ2 to prevent turning over.

Further, the scraper 31 is provided with the bent portion 34, so that the rigidity in the longitudinal direction is improved. However, since a large number of slits 35 are formed, the rigidity is reduced and the longitudinal direction is provided with flexibility. Therefore, even if the scraper 31 has a dimensional error, a mounting error, a deformation, or the like, or the developing roller 13 is bent and the edge 33 and the developing roller 13 are partially separated from each other, the scraper 31 follows the developing roller 13. Is deformed, and the edge 33 abuts the surface of the developing roller 13 over the entire length without a gap. That is, the problems such as the single contact shown in FIG. 9A and the floating shown in FIG. 9B do not occur.

As described above, the scraper 31 has the bent portion 3
4 is formed and the set angle θ1 and the working angle θ2 are appropriately set, and since many slits 35 are formed in the longitudinal direction, the edge 33
Accurately contacts the entire surface of the developing roller 13. Therefore, it is possible to prevent the occurrence of the toner history on the surface of the developing roller 13 and to obtain a good developed image quality in which ghost does not always occur.

Next, another embodiment based on the first embodiment will be described. In the reference diagram, the same components as those in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted.

B. Second Embodiment B-1. Configuration of Second Embodiment (FIG. 4) FIG. 4 shows a second embodiment of the present invention. In this scraper device 40, a flexible film (covering member) 41 that collectively covers the slits 35 is attached to the upper surface of the scraper 31 of the first embodiment.

B-2. According to the scraper device 40 of the second embodiment, even if the width of the slit 35 is wide, the toner T separated from the developing roller 13 is removed.
Does not fall into the slit 35 but is conveyed on the upper surface of the scraper 31 and surely returns to the toner tank 17. If the toner T drops through the slit 35, it may drop on the surface of the developing roller 13 cleaned by the scraper 31 and adhere to it in spots. Thus, if the toner T adheres to the surface of the developing roller 13 before the toner T in the toner chamber 24 adheres, it adversely affects the formation of a uniform toner layer and the spots are stretched in terms of image quality. The so-called "muscle unevenness" occurs, in which muscles are formed. However, in the present embodiment, although the slit 35 is formed, since the film 41 is attached, such a problem does not occur, and good image quality can be obtained.

C. Third Embodiment C-1. Configuration of Third Embodiment (FIG. 5) FIG. 5 shows a third embodiment of the present invention. In the scraper device 50, a large number of grooves (flexibility imparting means) 51 are formed in the scraper 31 instead of the slits 35 of the first embodiment. These grooves 51 are formed along the direction from the edge 33 toward the base end portion 32 and at equal intervals, except for the remaining portion 31a which is the front end edge.

C-2. Actions and Effects of Third Embodiment Due to the large number of grooves 51, the scraper 31 is provided with flexibility in the longitudinal direction like the slits 35, and thus the edge 33 is provided.
Accurately contacts the entire surface of the developing roller 13. Further, the large number of grooves 51 function as a conveyance path for the toner T, and the toner T is smoothly conveyed toward the toner tank 17.

D. Fourth Embodiment D-1. Configuration of Fourth Embodiment (FIG. 6) FIG. 4 shows a fourth embodiment of the present invention. In the scraper 31 of this scraper device 60, the bent portion 34 is gently curved. Further, the slit 35 and the groove 51 are not formed.

D-2. Action and effect of the fourth embodiment The scraper 31 has the bent portion 34 formed gently, so that the rigidity in the longitudinal direction is ensured and the scraper 31 also has appropriate flexibility. Therefore, it has flexibility in the longitudinal direction without forming slits or grooves, so that the edge 33 (not visible in FIG. 6) accurately contacts the surface of the developing roller 13 over the entire length. Further, since it is not necessary to form slits or grooves, the manufacturing cost is reduced.

E. Modifications of the Present Invention The present invention is not limited to the above-described embodiments, and various modifications can be made, for example, as follows. The edge 33 of the scraper 31 is always connected to the developing roller 13
In order to surely contact the surface of the scraper with an appropriate pressure, a pressing member that presses the scraper 31 from the upper surface is provided. The pressing member is preferably one having an elastic force such as a spring. A plurality of bent portions 34 are formed so that the contact point of the edge 33 with the developing roller 13 can be changed. In the first embodiment, the slit 35 is formed in a broken line shape in consideration of the balance between the rigidity and the flexibility of the scraper 31. In the second embodiment, the film 41 is attached to the lower surface or the upper and lower surfaces of the scraper 31. It is applied not only to the developing roller 13 of the developing device 11 but also as a cleaning blade for removing the toner adhering to the surface of the photosensitive drum 12. The invention is not limited to the image forming apparatus, but can be widely applied as an apparatus for peeling and removing the unwanted matter attached to the surface of the rotating cylindrical body.

[0040]

As described above, according to the invention described in claim 1 of the present invention, the scraper is not deformed under the influence of the rotation of the cylindrical body due to the bent portion formed on the tip edge side. , And because the tip edge contacts the surface of the cylinder at the most appropriate angle for peeling off unwanted deposits,
The deposits on the surface of the cylinder are effectively separated.

According to the invention of claim 2 of the present invention,
The scraper is provided with flexibility in a direction along the axial direction of the cylindrical body by a plurality of flexibility imparting means including slits or grooves. Therefore, even if the scraper has dimensional error, mounting error, deformation, etc., or even if the cylinder is bent, the scraper deforms following the cylinder and the entire length of the edge abuts the surface of the cylinder without any gap. Therefore, the peeling residue of the attached matter can be prevented.

According to the invention of claim 3 of the present invention,
Since the scraper is provided with the covering member that covers the flexibility imparting means, even if the flexibility imparting means is a slit, the adhered matter does not drop from the slit, and unnecessary troubles due to the fall are not caused.

[Brief description of drawings]

FIG. 1 is a side sectional view of a developing device to which a scraper device according to a first exemplary embodiment of the present invention is applied.

FIG. 2 is a perspective view of the scraper device according to the first embodiment of the present invention.

FIG. 3 is a side view of the same.

FIG. 4 is a side view of a scraper device according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a scraper device according to a third embodiment of the present invention.

FIG. 6 is a perspective view of a scraper device according to a fourth embodiment of the present invention.

FIG. 7 is a side view showing an example of a conventional scraper device.

FIG. 8 is a side view showing another example of the conventional scraper device.

FIG. 9 is a perspective view showing (a) a defect of a conventional scraper device, and (b) a perspective view showing another defect.

[Explanation of symbols]

10, 40, 50, 60 ... scraper device, 13 ... developing roller (cylindrical body), 19 ... partition wall (support member), 31 ...
Scraper, 32 ... Base end portion, 34 ... Bent portion, 33 ... Edge (tip edge), 35 ... Slit (flexibility imparting means), 4
1 ... Film, (covering member), 51 ... Groove (flexibility imparting means), S ... Plane, T ... Toner (adhered matter).

Claims (3)

[Claims] 1. A scraper device for removing deposits on a surface of a rotating cylindrical body, comprising: a scraper made of a plate-like elastic body; and a support member for supporting the scraper, wherein the scraper is the support member. A base end supported by the front end and a tip edge facing the surface of the cylindrical body in the rotational direction and elastically abutting, and further, a center between the base end and the tip edge. The scraper device is characterized in that a bent portion projecting from a plane connecting the base end portion and the tip edge to the side opposite to the cylindrical body is formed on the tip edge side of the portion. 2. The scraper is provided with a plurality of flexibility imparting means including slits or grooves extending from the leading edge along the base end direction at equal intervals in the axial direction of the cylindrical body. The scraper device according to claim 1, wherein: 3. The scraper device according to claim 2, wherein the scraper is provided with a covering member that covers the flexibility imparting means.