JPS6275563A - Forming device for toner layer thickness - Google Patents

Abstract

PURPOSE:To prevent an elastic member from a generating deterioration due to the use of it for a long period by forming a pressing force exciting means for exciting pressing force from the back side of the elastic member to a toner carrier to excite the prescribed pressing force to a bent part on the basis of cooperated action of the pressing force exciting means and the elastic member. CONSTITUTION:A fixed N magnetic pole 5a is arranged on a position of a fixed magnet integrating body 5 included in a non-magnetic sleeve 1 where is close to the bent part 2a of the elastic member 2 on the upper side of the bent part 2a. On the other hand, a rod-like magnet body 13 having polarity (S pole) different from said fixed polarity 5a is arranged on a position of the back side of the elastic member 2 corresponding to the fixed member 5a where is slightly separated from the bent part 2a on the upper side of the bent part 2a. In this case, the elastic member 2 is formed by a non-magnetic metallic elastic plate such as an aluminium plate and a phosphorous bronze plate and the fixed magnetic pole 5a is arranged separately from the bent part 2a. Consequently, pressing force is excited upon the elastic member 2 by magnetic suction force between the magnetic body 13 and the fixed magnetic pole 5a and the elastic member is always fixed without the generation of a secular change even if the member is used for a long period because the pressing force is magnetic force.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a toner layer thickness forming device applied to an electrophotographic development method that performs development using magnetic toner, and particularly relates to a toner layer thickness forming device that is applied to an electrophotographic development method that performs development using magnetic toner. The present invention relates to a toner layer thickness forming device that uses a thin plate-like elastic member as a layer thickness regulating member and regulates the layer thickness by pressing a bent portion of the elastic member onto a toner carrier.

"Prior Art" Conventionally, for example, a DC bias or an alternating bias voltage is applied to a development position together with the electric field of an electrostatic image without directly contacting the toner layer with an electrostatic holding surface, and the electric field effect causes the toner to In the so-called non-contact electrophotographic development method in which a toner layer is selectively flown onto an electrostatic holding surface, the thickness of the toner layer carried on a toner carrier at the development position is determined by the development distance between the toner holding surface and the electrostatic holding surface. Since the toner layer thickness must be set to a value equal to or smaller than the interval, the toner layer thickness regulation performed upstream of the development position requires not only thinning but also the formation of a smooth and homogeneous toner layer with the desired thickness and no unevenness. is requested.

In order to satisfy this requirement, the present applicant first used a thin plate-like elastic member bent in a direction perpendicular to the toner transport direction as a toner layer thickness regulating member that contacts the toner carrier.
A toner layer thickness forming device that regulates the layer thickness by bringing the bent portion of the elastic member into pressure contact with the toner carrier, thereby effectively regulating the layer thickness through line contact while taking advantage of the advantages of surface contact. is proposed. (Patent application 1980-15522
No. 7) "Problems to be Solved by the Invention" According to the prior art, it is possible to form a thin toner layer with a desired thickness at all times with high precision, and the above-mentioned requirements are met, and the layer is Although it is possible to provide a layer thickness regulating means that uniformizes the toner charge at the thickness regulating position and does not cause fogging, bleeding, white streaks, etc., a thin plate-like elastic member is used as the layer thickness regulating member. Due to long-term use, the elastic force of the elastic member decreases, that is, it becomes sagging, and this sagging does not occur uniformly in the pressure-welded area due to line contact, but only partially. This immediately appears as a disturbance in the film thickness in the transport direction, making it difficult to form a good image.

Further, in order to prevent toner from scattering at both ends of the toner carrier perpendicular to the toner transport direction, a seal such as a sponge is installed between the upstream side of the bent portion of the elastic member and the toner carrier at both ends. Although there are cases where parts are interposed,
With such a configuration, the reaction force (force resisting the pressure contact force of the elastic member) applied to the elastic member is different at both end positions with the seal member interposed and at the center position sandwiched between the seal members. Therefore, it is close to the both end positions and the side end positions. Sagging occurs first at the bent portion of the elastic member, and as a result, the toner film thickness at both end sides becomes thicker, which also makes it difficult to form a good image.

In order to eliminate this drawback, it is conceivable to increase the elastic force of the elastic member by increasing the thickness of the elastic member, but with this configuration, the radius of curvature at the bending angle of the bent portion of the elastic member is large. As a result, the toner carrying member cannot be brought into contact with the toner carrier substantially by line contact, but by surface contact, and the toner adheres or adheres to the contact surface, resulting in a toner layer. The thickness is disturbed, and the effect of the prior art cannot be smoothly achieved.

Furthermore, when the elastic member is made thick, the Young's modulus becomes larger than when the elastic member is thin, so even a slight change in the amount of arm bending causes a large change in the elastic force, that is, the pressure contact force. As the mounting precision increases, it becomes extremely difficult to obtain a desired film thickness, and similarly the effects of the prior art cannot be smoothly achieved.

The present invention maintains the thinning of the member described above and the substantial line contact of the bent portions, and smoothly achieves the effects of the prior art, while also addressing the problems of the prior art. It is an object of the present invention to provide a toner layer thickness forming device that can prevent the elastic member from becoming sagging due to long-term use and, as a result, can consistently form a uniform and smooth toner layer.

Another object of the present invention is that even when sponges or other sealing members are interposed on both ends of the toner carrier,
It is an object of the present invention to provide a toner layer thickness forming device capable of equalizing and stabilizing the pressure contact force between a bent portion and a toner carrier in a direction perpendicular to the toner transport direction (hereinafter referred to as the axial direction).

In order to achieve this technical problem, the present invention, for example, as shown in FIG. In a toner layer thickness forming apparatus that uses a thin plate-shaped elastic member 2 bent in orthogonal directions and presses the bent portion 2a of the elastic member 2 onto the toner carrier 1 to regulate the layer thickness, the elastic member 2 The member 2 has a pressing force urging means 3 that applies a pressing force toward the toner carrier 1 from the back side, and the urging means 3 is small and located on both side ends of the co-elastic member 2, and has a bent portion. Placed in a position separated from 2a,
A technical means is proposed in which a predetermined pressing force is applied to the bent portion 2a by the cooperative action of the suppressing force urging means 3 and the elastic member 2, and the pressing force is made uniform.

In the Naoki technical means, the material and shape of the elastic member 2 are as explained in the prior art, but to briefly explain again based on FIG. 1, the elastic member 2 is made of an aluminum plate,
It is formed of a metal elastic plate such as phosphor bronze, SUS, etc., and has a wall thickness of 0.05 to 0.5 ff1m, and a radius of curvature R of the bent portion 2a of 0.15 to 0.5 mm, and furthermore, Penetration angle (θl), bending angle (02), relief angle (0
By setting 3) as shown below, the pressure contact area A between the elastic member 2 and the toner carrier 1 can be maintained in substantially line contact. 01:], O'~90',
θ2: lO"~1GO', 03:10°~(160
-θl)' The invention can exhibit a preferable effect when the pressure contact area A is substantially a line contact, but it is not necessarily limited to this, and the pressure contact area A is a thin strip-like surface contact. It can also be applied to cases close to .

"Operation" According to this technical means, the pressing force biasing means 3 that biases the pressing force toward the toner carrier 1 from the back side of the elastic member 2 is arranged at a position apart from the bent portion 2a. (1) A stable pressing force can always be applied to the bent portion 2a without reducing the effect of making the elastic member 2 thinner, and without changing even after long-term use.

That is, in the prior art, since the pressing force at the pressure contact area A is obtained only by the elastic member 2, the elastic member 2
Unless the arm is bent to a certain extent, the desired pressing force cannot be obtained, and as a result, the elastic member 2 described above tends to become sagging.

However, according to the present invention, the cooperative action between the pressing force urging means 3 and the elastic member 2, in other words, the amount of arm bending (elastic force) of the elastic member 2 is reduced, and the pressing force of the pressing force urging means 3 is reduced. Since the applied force only needs to be a predetermined pressure contact force at the pressure contact portion A, it is inevitable that the elastic member 2 is less likely to sag, and even if the elastic force of the elastic member 2 changes due to the stagnation, it will not change. This does not directly lead to fluctuations in the pressing force at the pressing portion A, and as a result, it is possible to always form a stable and smooth toner layer thickness.

Furthermore, in a device in which a sponge or other sealing member is interposed on both side ends of the toner carrier 1, the elastic member 2 is likely to sag from a portion close to the sealing member. Since the pressing force biasing means 3 is disposed on the end side at a position corresponding to or in the vicinity of the sealing member, the pressing force at the press contact area A will not weaken even after long-term use.

Therefore, by stabilizing the suppressing force and making the pressing force uniform in the axial direction, the toner film thickness on both end sides does not change in the axial direction, making it possible to always form a stable and smooth toner layer thickness.

Further, according to the present invention, the pressing force urging means 3 is connected 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 bent portion 2a
A magnet body 13 may be disposed on the back side of the elastic member 2 in the vicinity of the elastic member 2 (see FIGS. 2 and 3 below). The tape body 23.23° may be stretched and disposed (see FIGS. 4 and 5), and further pressed using a plate-shaped elastic member 33.33' having a wall thickness larger than that of the elastic member 2. It may be good (6th
(see Figures 7 to 7), 4 using such a pressing force urging means 3
t allows for better stabilization of the toner layer thickness.

Furthermore, according to the present invention, since the pressing force biasing means 3 is disposed at a position apart from the bent portion 2d, the elastic effect of the bent portion 2a and the thinning of the elastic member 2 can be achieved in the prior art. Since the elastic force can be stabilized without reducing the effect to the same extent, the effect of the prior art can be further enhanced.

Embodiment j Hereinafter, a preferred embodiment of the present invention will be explained in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangement of the components described in this embodiment are particularly Unless specifically stated, the scope of the present invention is not intended to be limited thereto, and is merely an illustrative example.

1 to 3, 4 to 5, and 6 to 7 all show developing devices according to first, second, and third embodiments of the present invention, and first, common components thereof will be explained.

The non-magnetic sleeve l is made of aluminum or other non-magnetic metal material, is configured to be rotatable at a predetermined peripheral speed in the direction of the arrow, and has a surface roughness of 0.5 to 20 islands. . Note that the outer peripheral surface may be formed as fine uneven grooves in a hairline shape.

4 is a photoreceptor drum, and the development interval between the photoreceptor drum 4 and the nonmagnetic sleeve l is set to be slightly larger than the toner layer thickness at the development position.

5 is a fixed magnet assembly contained within the sleeve 1;
In the case of the first embodiment, the pressure contact portion A of the elastic member 12 is particularly
An N-pole fixed magnetic pole 5a is arranged on the upstream side close to. 6 is a DC pulse generation circuit connected to the sleeve 1.

The thin plate-like elastic member 2, which is a toner layer thickness regulating member, has its proximal end fixedly attached to a support member 8 formed with a groove at the outlet of the toner container 7, and its free end side bent at a predetermined curvature. The bent part 2
A is brought into contact with the circumferential surface of the sleeve 1 with a predetermined pressing force so as to substantially form a line contact.

A sponge-like seal member 9 is crushed and held between the upstream side of the bent portion 2a of the elastic member 2 and the support member 8 on both side ends of the sleeve 1, and the seal member 8 holds the sleeve 1 on both sides. The space between the bent portions 2a of the side elastic member 2 is sealed to prevent the toner from falling and scattering from the both ends.

According to such a configuration, as is well known, after the high-resistance magnetic I-toner negatively charged by frictional electrification in the toner container 7 is carried on its circumferential surface and transported to the development position,
By the electric field effect of the switching bias generated by the generating circuit 6, the toner carried on the sleeve 1 is selectively flown onto the electrostatic holding surface, and the above-described non-contact electrophotographic development of the toner layer can be performed.

Next, the main structure of each of the above-mentioned embodiments will be explained.As described above, the fixed magnet assembly 5 contained in the non-magnetic sleeve 1 is placed on the upstream side of the bent portion 2a of the elastic member 2. Further, a fixed magnetic pole 5a having an N pole is disposed at a position close to the bent portion 2a.

Further, on the back side of the elastic member 2 corresponding to the fixed magnetic pole 5a, at a position on the upstream side of the bent portion 2a slightly spaced from the bent portion 2a,
A bar-shaped magnet body 13 having a different polarity (S polarity) from the fixed magnetic pole 5a 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 bent portion 2
The reason why they are arranged apart from a is to maintain the elastic force of the elastic member 2 at the bent portion 2a.

According to this embodiment, a pressing force is applied to the elastic member 2 due to the magnetic attractive force between the bar-shaped magnet body 13 and the fixed magnetic pole 5a, and since the suppressing force is a magnetic force, it will not deteriorate over time even after long-term use. It remains constant without any change.

FIGS. 4 and 5 show a developing device according to a second embodiment of the present invention, in which a pair of tape members 23 and 23' are arranged extending parallel to the toner conveying direction along both side ends of the elastic member 2, After fixing one end side of the tape body 23, 23' to the threaded part 81 of the support member 8, the non-magnetic sleeve located on the downstream side passes over the elastic member 2 and presses against the free end 2b side of the elastic member 2. The tape body 23.23' is brought into contact with the surface, and the other end side of the tape body 23.23' is fixed to a stop 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 tension of the tape body 23.23' is A pressing force is applied to the bent portion 2a while pressing the free end 2b side of the elastic member 2 with the force.

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

In this case, the tape body 23.23° may be made of a resin tape with low frictional resistance, or may be made of an adhesive tape or the like so that the toner adheres to the adhesive surface.

According to this embodiment, a constant pressing force is always applied to the elastic member 2 due to the tensile force of the tape body 23.23', and the suppressed position of the tape body 23.23' is approximately equal to the sealing member 9. Since they are on both opposite end sides, the pressing force is strongest near the seal member S, and the suppressing force is balanced with the reaction force of the seal member 8, and the pressing force is applied to the pressed part of the bent portion 2a in the axial direction. A uniform pressing force is applied along the line.

Further, the tape body 23, 23' is placed in contact with the peripheral surface of the non-magnetic sleeve 1 on the downstream side of the toner regulation level.
Since it extends to the downstream side of the development position, it is possible to prevent toner from scattering toward the end side of the non-magnetic sleeve 1 downstream of the toner regulation position.

6 and 7 show a developing device according to a third embodiment of the present invention, in which a pair of plate-shaped elastic members 33, 33° having a wall thickness larger than that of the elastic member 2 are used. 33.3
The base end of 3' is fixed to the screw part 81, and the free end side is extended so as to be located at least below the lower end position of the co-supporting member 8, and the back side of the elastic member 2 on both ends of the bent part 2a. 4 so as to bias the elastic force more toward the non-magnetic sleeve 1 side.
! has been completed.

According to this embodiment, since the plate-like elastic members 33 and 33' have a wall thickness larger than that of the elastic member 2, there is little risk of fatigue occurring even after long-term use, and as a result, the elastic member 33, 33' is always maintained at a constant pressure. A pressing force is applied to the member 2, and since the pressing position of the plate-shaped elastic member 33, 33° is a position facing the sealing member 9, the pressing force is applied to the bent portion 2a along the axial direction. Uniform contact force will be applied.

"Effects of the Invention" As described above, according to the present invention, the effects of the prior art, which are brought about by the thinning of the elastic member and the bent portion, can be smoothly achieved, while the problems of the prior art can be achieved. This prevents the elastic member 2 from becoming sagging due to long-term use, and as a result, a uniform and smooth toner layer can always be formed stably.

Further, according to the present invention, even when a sponge or other seal member is interposed on both ends of the toner carrier, the pressure contact force between the bent portion and the toner carrier in the axial direction can be made uniform. I can do it.

Therefore, the present invention has various remarkable effects such as being able to consistently form stable and good images even after long-term use.

[Brief explanation of drawings]

1-3, FIG. 4-5, and FIG. 6-7 all show the first, second, and third embodiments of the present invention, and FIG.
4 and 6 are schematic sectional views of each embodiment, and FIGS. 3, 5, and 7 are perspective views of essential parts thereof. FIG. 1 is an enlarged view of the main part of FIG. 2, and also serves as a diagram for explaining the principle of the present invention. Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Procedure amendment November 1985 to r date

Claims (1)

[Claims] 1) A thin plate-like elastic member bent in a direction perpendicular to the toner transport direction is used as a toner layer thickness regulating member that contacts the toner carrier, and the bent portion of the elastic member A toner layer thickness forming device that regulates layer thickness by being brought into pressure contact with a carrier, comprising a pressing force biasing means for biasing a pressing force from the back side of the elastic member toward the toner carrier, the biasing unit 2) The toner layer thickness forming device is characterized in that the co-elastic member is located at both ends of the co-elastic member and is spaced apart from the bent portion.2) The pressing force biasing means is located close to the bent portion. 3) The toner layer thickness forming device according to claim 1, wherein the toner layer thickness forming device is a magnet disposed on the back side of the elastic member. Formed by a pair of tape bodies extending in parallel, one end of the tape body is fixed above an elastic member, and then the peripheral surface of the toner carrier positioned downstream of the free end of the elastic member is pressed. 4) The toner layer thickness forming device according to claim 1, wherein the other end side of the tape body is fixed on the downstream side of the development position of the carrier 4) The pressing force biasing device means biases an elastic force toward the toner carrier from a rear position of the elastic member upstream of the bending portion;
The toner layer thickness forming device according to claim 1, wherein the toner layer thickness forming device is a plate-like elastic member having a wall thickness greater than that of the elastic member.