JPH0652449B2 - Toner layer thickness forming device - Google Patents

Description

The present invention relates to a toner layer thickness forming apparatus applied to an electrophotographic developing method in which a magnetic toner is used for development.

“Conventional Technology” Conventionally, for example, a direct current bias or an alternating bias voltage is applied to a developing position together with an electric field of an electrostatic image without directly contacting a toner layer with an electrostatic holding surface. In the so-called toner layer non-contact type electrophotographic development system, in which the toner is selectively flown onto the electrostatic holding surface, the toner layer thickness at the developing position carried on the toner carrier is determined by the development between the electrostatic holding surface and the toner layer thickness. Since the distance must be set to be equal to or less than the interval, the toner layer thickness regulation performed on the upstream side of the developing position is to form a thin and smooth toner layer having a desired film thickness and no unevenness. Is requested.

In order to satisfy such a request, the present applicant has previously proposed that a toner layer thickness regulating member that comes into contact with the toner carrier is used as a toner layer thickness regulating member that comes into contact with the toner carrier and that a cross-section of the toner layer thickness regulating member is perpendicular to the toner carrying direction. It is bent into a V shape, and the V-shaped corner is slightly rounded, specifically at least 1 m.
A thin plate-shaped elastic member having a slight radius of curvature of m or less and forming a slightly R-shaped bent corner is used, and the bent corner of the elastic member is pressed onto the toner carrier to regulate the layer thickness. By doing so, a toner layer thickness forming device is proposed in which the advantages of surface contact are utilized and the layer thickness is substantially regulated by line contact. (Japanese Patent Application No. 60-155227, the present technology is not known, and will be referred to as a basic invention hereinafter) "Problems to be solved by the invention" According to the basic invention, a thin film having a desired film thickness can be obtained with high accuracy at all times. To provide a layer thickness regulation means capable of forming a toner layer thickness, satisfying the above-mentioned requirements, and uniformizing the charging of the toner at the layer thickness regulation position without causing fog, bleeding, and white streaks. However, since a thin plate-shaped elastic member is used as the layer thickness control member, the elastic force of the elastic member is reduced over a long period of time, that is, settling occurs, and the settling is even at the pressure contact portion due to line contact. Since it does not occur in the first place, but occurs partially, it immediately appears as a disturbance in the film thickness in the transport direction, which may make it difficult to form a good image.

Further, in order to prevent the toner from scattering on both side ends of the toner carrier perpendicular to the toner conveying direction, the toner is substantially in line contact with the elastic member or the upstream side of the narrow strip-shaped bent corner portion at the both side end positions. In some cases, a sponge or other seal member is interposed between the carriers. However, with such a structure, the elastic member is applied at both end positions with the seal member and a central position sandwiched by the seal members. Because the reaction force (the force that resists the pressure contact force of the elastic member) is different,
The bent corners of the elastic member, which are close to the both side end positions and the side end positions, are firstly settled, and as a result, the toner film thickness on both side end sides becomes thicker, and good image formation is still obtained. Make it difficult.

In order to solve such a drawback, it is conceivable to increase the elastic force of the elastic member by thickening the elastic member. However, with this structure, the radius of curvature at the bending angle of the bending angle portion of the elastic member becomes large. As a result, the contact with the toner carrier cannot be made substantially in line contact, and contact is made by surface contact having a predetermined width. When the toner is deposited, the thickness of the toner layer is disturbed, and the effects of the basic invention cannot be achieved smoothly.

When the elastic member has a large thickness, the Young's modulus becomes larger than that when the elastic member has a small thickness, and therefore the elastic force, that is, the pressure contact force, changes greatly even if the arm bending amount is small. As the mounting accuracy increases, it becomes extremely difficult to obtain a desired film thickness, and similarly, the effects of the basic invention cannot be achieved smoothly.

The present invention maintains the thin plate of the elastic member and the substantial line contact work of the bent corner portion, while smoothly achieving the effect of the basic invention, which is a problem of the basic invention. It is an object of the present invention to provide a toner layer thickness forming apparatus capable of preventing the elastic member from being settled due to the above, and as a result, stably and always forming a uniform and smooth toner layer.

Another object of the present invention is to provide a sponge or other sealing member on both sides of the toner carrier,
An object of the present invention is to provide a toner layer thickness forming device capable of making the pressure contact force between the bent corner portion and the toner carrier uniform and stable in the direction orthogonal to the toner transport direction (hereinafter referred to as the axial direction).

[Means for Solving the Problems] In order to achieve the technical problem, the present invention is a fold formed in a slightly R shape with a minute radius of curvature of at least 1 mm as shown in FIG. Using a thin plate-shaped elastic member 2 bent into a substantially rectangular cross section through a bent corner 2a,
The bent corner portion 2a of the elastic member 2 is pressed against the toner carrier 1 along a direction orthogonal to the toner transport direction to form a toner layer thickness regulating member, and the toner carrier is arranged from the back side of the elastic member 2. A pressing force urging means 3 for urging a pressing force toward 1 is provided, and the urging means 3 is less in number at both side ends of the elastic member 2 and at a position separated from the bent corner portion 2a. A technical means is proposed in which the pressing force urging means 3 and the elastic member 2 cooperate with each other to urge a predetermined pressing force to the bent corner portion 2a to make the pressure contact force uniform.

In the present technical means, the material and shape of the elastic member 2 are as described in the basic invention, but the elastic member 2 is made of an aluminum plate, as briefly described repeatedly with reference to FIG.
It is made of phosphor bronze, SUS or other metal elastic plate and has a wall thickness of 0.05 to 0.5 mm and a radius of curvature R of the bent corner 2a.
Is at least 1 mm or less, more preferably 0.15 to 0.5 mm
And the penetration angle of the bent corner 2a (θ
1), the bending angle (θ2) and the clearance angle (θ3) are set as follows, respectively, so that the pressure contact portion A between the elastic member 2 and the toner carrier 1 can be maintained substantially in line contact.

θ1: 10 ° to 90 °, θ2: 10 ° to 160 °, θ3: 10 ° to (160 −θ1) ° Therefore, the fact that the above-mentioned V-shaped cross section is formed is not necessarily the present invention. A may exert a preferable effect when it is substantially in line contact, but it is not necessarily limited to this, and it is particularly problematic if it is a strip-shaped bent corner portion formed by a radius of curvature of at least 1 mm or less. Does not occur.

[Operation] According to such technical means, the pressing force urging means 3 for urging the pressing force from the back surface side of the elastic member 2 toward the toner carrier 1 is arranged at a position separated from the bending angle 2a. Therefore, it is possible to constantly apply a stable pressing force to the thin strip-shaped bending angle 2a without reducing the effect of thinning the elastic member 2 and changing over a long period of use.

That is, in the basic invention, since the pressing force at the press contact portion A is obtained only by the elastic member 2, the elastic member 2
Unless the arm is bent to some extent, a desired pressing force cannot be obtained, and therefore the elastic member 2 is liable to settle.

However, according to the present invention, the cooperation between the pressing force urging means 3 and the elastic member 2, that is, the arm bending amount (elastic force) of the elastic member 2 is reduced, and the pressing force of the pressing force urging means 3 is reduced. Since what is added is required to have a predetermined pressure contact force at the pressure contact portion A, it is inevitable that the elastic member 2 does not easily settle, and even if the elastic force of the elastic member 2 changes due to the settling Does not directly lead to fluctuations in the pressing force at the pressed portion A, and as a result, it is possible to always form a stable and smooth toner layer thickness.

Further, in a device in which a sponge or other seal member is interposed on both end sides of the toner carrier 1, the elastic member 2 is apt to be settled from a portion in the vicinity of that portion. Since the pressing force urging means 3 is arranged on the end side at a position corresponding to the seal member or a position close to the seal member, the pressing force at the pressure contact portion A does not weaken even after long-term use.

Therefore, by stabilizing the pressing force and homogenizing the pressing force in the axial direction, the toner film thickness on both side ends does not change in the axial direction, and it is possible to always form a stable and smooth toner layer thickness.

Further, according to the present invention, the pressing force urging means 3 is attached to the elastic member 2.
Since it is configured separately from the elastic member 2, the most preferable shape and material can be selected regardless of the elastic member 2. For example, the magnet body 13 is arranged on the back side of the elastic member 2 close to the bent corner portion 2a. Alternatively (see FIGS. 2 and 3 below), a pair of tape members 23, 23 'extending along both ends of the elastic member 2 in parallel with the toner conveying direction may be pulled and arranged. (See FIGS. 4 to 5) Further, the elastic member 2 may be pressed by using plate-like elastic members 33 and 33 'having a thickness larger than that of the elastic member 2 (see FIGS. 6 to 5).
(See FIG. 7), by using such a pressing force urging means 3, it is possible to further stabilize the toner layer thickness.

Further, according to the present invention, the pressing force urging means 3 has the bending angle 2a.
Since it is arranged at a position spaced apart from each other, the elastic effect of the bent corner portion 2a and the effect of the basic invention due to the thinning of the elastic member 2 can be reduced and the elastic force can be stabilized. In addition, the effects of the basic invention can be further promoted.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be exemplarily described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only thereto, but merely illustrative examples. Nothing more than.

FIGS. 1 to 3, 4 to 5 and 6 to 7 each show a developing device according to the first, second and third embodiments of the present invention. First, the common components will be described.

The non-magnetic sleeve 1 is made of a non-magnetic metal material such as aluminum, is configured to be rotatable in the arrow direction at a predetermined peripheral speed, and has a surface roughness of its outer peripheral surface set to 0.5 to 20 μm. Incidentally, the outer peripheral surface may be formed as fine irregular grooves in a hairline shape.

Reference numeral 4 denotes a photosensitive drum, which sets the developing interval between the photosensitive drum 4 and the non-magnetic sleeve 1 to be slightly larger than the toner layer thickness at the developing position.

5 is a fixed magnet assembly contained in the sleeve 1,
In the case of the first embodiment, in particular, an N pole fixed magnetic pole 5a is arranged on the upstream side of the elastic member 12 in the vicinity of the press contact portion A.
6 is a DC pulse generation circuit connected to the sleeve 1.

The thin plate-like elastic member 2 serving as a toner layer thickness regulating member has its base end side fixed to the support member 8 formed at the outlet of the toner container 7, and its free end side having a radius of curvature R of 0.15 to 0.5 mm. Bent in a rectangular shape with a curvature, and the bent portion (hereinafter referred to as a bent corner portion) 2a
Is brought into contact with the circumferential surface of the sleeve 1 with a predetermined pressing force and substantially in line contact.

A sponge-like seal member 9 is crushed and pinched between the support member 8 and the upstream side of the bending corner 2a of the elastic member 2 on both side ends of the sleeve 1, and both sides of the sleeve 1 are supported by the seal member 9. The end portions of the elastic member 2 are sealed between the bent corner portions 2a to prevent the toner from dropping and scattering from the both end sides.

According to such a construction, as is well known, after the high resistance magnetic toner negatively charged by frictional charging in the toner container 7 is carried on the peripheral surface thereof to the developing position, the toner is generated by the generating circuit 6. By the electric field effect of the formed switching bias, the toner carried on the sleeve 1 can be selectively flown to the electrostatic holding surface to perform the above-mentioned toner layer non-contact type electrophotographic development.

Next, the structure of the main part of each of the above-mentioned embodiments will be described.

FIGS. 1 and 3 show a developing device according to the first embodiment of the present invention. As described above, the elastic member 2 and the bent corner portion 2a of the fixed magnet assembly 5 contained in the non-magnetic sleeve 1 are described. A fixed magnetic pole of N pole at a position upstream of the and close to the bent corner portion 2a.
Arrange 5a.

Further, on the back side of the elastic member 2 corresponding to the fixed magnetic pole 5a, at a position upstream of the bent corner 2a slightly separated from the bent corner 2a, there is a rod shape having a different polarity (S pole) from the fixed magnetic pole 5a. A magnet body 13 is provided.

In this case, the elastic member 2 is formed of a non-magnetic metal elastic plate such as an aluminum plate or phosphor bronze. The fixed magnetic pole 5a is bent at the corner 2a.
The reason why they are arranged apart from is that the elastic force of the elastic member 2 at the bent corner portion 2a is retained.

According to this embodiment, a pressing force is applied to the elastic member 2 by a magnetic attraction force between the bar-shaped magnet body 13 and the fixed magnetic pole 5a, and since the pressing force is a magnetic force, it may be aged even after many years of use. It is always constant regardless of changes.

4 and 5 show a developing device according to a second embodiment of the present invention, in which a pair of tape members 23, 23 'are arranged along both side ends of the elastic member 2 in parallel with the toner conveying direction, The tape body 23,
After fixing one end side of 23 'to the screw portion 81 of the support member 8, the elastic member 2 is passed over and the free end 2b side is pressed and brought into contact with the peripheral surface of the non-magnetic sleeve 1 located on the downstream side,
The other end of the tape body 23, 23 'is fixed to a stopper shaft 20 located at the lower end side of the toner container 7 and arranged parallel to the axis of the sleeve 1, and the elastic member 2 is applied by the pulling force of the tape body 23, 23'. The pressing force is applied to the bent corner portion 2a while pressing the free end 2b side of the.

Note that, instead of using the independent stop shaft 20 as in the present embodiment, it may be directly fixed to the lower end side of the toner container 7.

In this case, the tape bodies 23, 23 'may be resin tapes having low frictional resistance, or adhesive tapes may be used so that the toner adheres to the adhesive surfaces.

According to this embodiment, a constant pressing force is always applied to the elastic member 2 by the pulling force of the tape members 23, 23 ', and the pressing force position of the tape members 23, 23' is set at the sealing member 9.
The seal member 9 is located on the opposite side of the seal member 9 because
The pressing force is strongest in the vicinity, and the pressing force is
A uniform pressure contact force is applied to the pressure contact portion of the bent corner portion 2a along the axial direction in balance with the reaction force of the.

Further, since the tape bodies 23 and 23 'are extended to the downstream side of the developing position of the sleeve 1 while being in contact with the peripheral surface of the non-magnetic sleeve 1 on the downstream side of the toner regulating position, the tape body on the downstream side of the toner regulating position is It is possible to prevent the toner from scattering toward the end of the magnetic sleeve 1.

6 and 7 show a developing device according to a third embodiment of the present invention, in which a pair of plate-like elastic members 33, 33 'having a thickness larger than that of the elastic member 2 is used. The base ends of 33, 33 'are fixed to the screw portion 81, and the free end side thereof is extended so as to be located at least below the lower end position of the co-supporting member 8,
It is configured to apply an elastic force toward the non-magnetic sleeve 1 side from the back side of the elastic member 2 on both ends of the bent corner portion 2a.

According to such an embodiment, since the plate-like elastic members 33, 33 'have a thickness larger than that of the elastic member 2, there is less risk of settling due to long-term use, and as a result, the elasticity is always maintained at a constant pressure. Since a pressing force is applied to the member 2 and the pressing position of the plate-like elastic members 33, 33 'is the position facing the seal member 9, the bending contact portion of the bent corner portion 2a is axially aligned. Uniform pressure contact force is applied.

"Effects of the Invention" As described above, according to the present invention, while smoothly achieving the effects in the basic invention brought about by the bending angle portions of the elastic member and the thin plate, there is a problem of the basic invention. It is possible to prevent the elastic member from being settled due to long-term use, and as a result, it is possible to stably and always form a uniform and smooth toner layer.

According to the present invention, even when a sponge or other sealing member is interposed on both end sides of the toner carrier, the pressure contact force between the bent portion of the elastic member and the toner carrier in the axial direction is uniform. Can be changed.

Therefore, according to the present invention, there are various remarkable effects such that a stable and good image can be always formed even after long-term use.

[Brief description of drawings]

FIGS. 1 to 3, FIGS. 4 to 5 and FIGS. 6 to 7 all show the first, second and third embodiments of the present invention, and FIG.
FIGS. 4 and 6 are schematic sectional views of the respective embodiments, and FIGS. 3, 5, and 7 are perspective views of relevant parts. FIG. 1 is an enlarged view of an essential part of FIG. 2 and also serves as an explanatory view of the principle of the present invention.

Claims (4)

[Claims] 1. A thin plate-shaped elastic member bent into a substantially rectangular cross-section through bending corners formed in a slightly R shape with a minute radius of curvature of at least 1 mm or less, and folding of the elastic member. The curved portion is pressed against the toner carrier along the direction orthogonal to the toner conveying direction to form a toner layer thickness regulating member, and a pressing force is applied from the back side of the elastic member toward the toner carrier. Is provided on both sides of the elastic member.
Further, the toner layer thickness forming device is arranged at a position separated from the bent corner portion. 2. The toner layer thickness forming apparatus according to claim 1, wherein the pressing force urging means is a magnet body disposed on the back side of the elastic member adjacent to the bent corner portion. 3. The pressing force urging means is formed by a pair of tape members extending along both ends of the elastic member in parallel with the toner conveying direction, and one end side of the tape member is above the elastic member. After the fixing, the free end side of the elastic member is pressed and brought into contact with the peripheral surface of the toner carrier located downstream thereof, and the other end of the tape member is fixed downstream of the developing position of the carrier. An apparatus for forming a toner layer thickness according to claim 1, characterized in that 4. A plate having a wall thickness larger than that of the elastic member, wherein the pressing force urging means urges an elastic force from a rear surface position of the elastic member on the upstream side of the bent corner portion toward the toner carrier. The toner layer thickness forming device according to claim 1, wherein the toner layer thickness forming device is a substantially elastic member.