JP2978408B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing apparatus using a one-component developer used for an image forming apparatus such as an electrophotographic apparatus.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional one-component developing type image forming apparatus. 8, reference numeral 1 denotes a photosensitive drum as an image carrier, 2 denotes a charging roller, 3 denotes a non-magnetic developing sleeve as a developer carrier formed of an aluminum or stainless steel pipe, and a developing sleeve 3 denotes a developing device. The image forming apparatus is rotatably mounted at a position of an opening facing the photosensitive drum 1 in a developing container 8 containing a magnetic toner 5 as a one-component developer. In the developing sleeve 3, a magnet 31 having a plurality of magnetic poles N and S alternately formed is installed immovably with respect to the rotation of the developing sleeve 3. Due to the magnetic action of the magnet 31, the toner 5 in the developing container 8 is rotated in the direction of arrow R2.
Carried on the surface of

At the position of the developing container 8 on the developing sleeve 3, an elastic blade 42 as a developer regulating member is
It is attached by bonding to 1. Elastic blade 42
Is in contact with the developing sleeve 3 at an abdomen of a free end portion of the developing sleeve 3 extending from the upper side in a direction opposite to the rotation direction indicated by the arrow R2 of the developing sleeve 3. The toner 5 carried on the developing sleeve 3
The thickness of the toner layer is regulated while passing through the contacting portion, whereby a thin toner layer is formed on the developing sleeve 3.

The toner layer on the developing sleeve 3 is conveyed to a developing section facing the photosensitive drum 1 by rotation of the developing sleeve 3, and the toner 5 is supplied to a latent image formed on the photosensitive drum 1. The latent image is developed and visualized as a toner image.

[0005] The obtained toner image is transferred onto a transfer material 10 by a transfer device (transfer roller) 9. Transfer roller 9
The transfer material 10 onto which the toner image has been transferred is transferred to a fixing device (not shown), where the toner image is fixed on the transfer material 10 by heat and pressure.
The sheet is discharged outside the image forming apparatus.

On the other hand, the photosensitive drum 1 is cleaned by a cleaning device 6 to remove the toner remaining on the surface thereof without being transferred, and then charged again by the charging roller 2 to repeat the image forming process.

In order to facilitate maintenance, the image forming apparatus uses the developing device 102 as a developing process unit and integrates the photosensitive drum 1, the charging roller 2, and the cleaning device 6 into an image forming process / cleaning unit. 101, each of these process units is installed in the apparatus main body as a detachable structure. Further, there has been widespread use of the above two units integrated as a process cartridge to further simplify maintenance.

The blade often holds the elastic blade with a metal plate 41 made of metal such as iron or aluminum. As one example, an elastic blade is made of two sheet metals,
Alternatively, there is a method of sandwiching between members that are comparable in strength. In this case, the elastic blade is often temporarily fixed to a member on one side to be sandwiched with a double-sided tape or the like for positioning. This is because the cost is low and the welding is not performed, so that the work safety is good.

[0009]

Incidentally, in recent years, there has been a tendency to reduce the particle diameter of toner to about 6 to 9 μm in order to improve the resolution of electrophotographic images. Smaller particle size toner has more particles per unit volume than larger particle size toner, so it is difficult to give each toner particle a chance to evenly contact the developing sleeve or blade surface, and to uniformly charge Difficult to let. In particular, in a non-contact developing type developing device, the charging efficiency of the toner is low and the toner is likely to be non-uniformly charged, the image density and the resolution are reduced, and the fogging of the non-image portion and the scattering of the toner are deteriorated.

For this reason, in order to uniformly charge the toner, the contact pressure between the elastic blade and the developing sleeve must be kept constant both in the longitudinal direction and up to the number of lifespans. For this purpose, the method of holding the elastic blade must be strong and stable.

In particular, as described above, in the method of sandwiching the elastic blade between the sheet metal and the sheet metal or a member having rigidity equivalent thereto, if the contact portion between the elastic blade and the sheet metal does not contact with uniform pressure over the entire area. Then, the elastic blade shifts or bends. For example,
If the spacer 43 is too high with respect to the thickness of the elastic blade 42 as shown in FIG. 9A, the elastic blade 42 does not receive the pressure from the sheet metal 41, so that it is very difficult to hold the elastic blade 42. Difficult. Further, if the pressure is too low as shown in FIG. 9B, the sheet metal 41 on the pressing side opens in a C-shape, and the elastic blade 42 is held in an unstable shape. In such a state, when the contact pressure is low, the influence is not so large. However, when the contact pressure is high, the elastic blade 42 is easily shifted, and a defective image such as uneven density often appears.

An object of a first invention according to the present invention is to solve the above-mentioned problems and to develop an image capable of obtaining an image without density unevenness by holding the elastic blade with a uniform pressure when sandwiching the elastic blade. It is to provide a device.

Another object of the present invention, in addition to the above objects, is to provide a developing device capable of improving the workability at the time of sandwiching.

Still another object of the third invention of the present application is to provide, in addition to the above objects, a developing device that does not deform even when an elastic blade receives a force from a developing sleeve.

Another object of the present invention is to provide a developing device in which the elastic blade is not displaced by an external force, in addition to the above objects.

[0016]

According to a first aspect of the present invention, the object is to provide a developing container for storing a developer,
A developer carrying member for carrying and transporting the developer; and an elastic developer regulating member disposed so that a free end thereof is in contact with the developer carrying member. In a developing device that transports the developer to a developing section facing the image carrier while developing a thin layer of the developer thereon, and develops and visualizes the formed latent image, the developer regulating member includes An end opposite to the free end is disposed between the supporting member attached to the developing container and a pressing member facing the supporting member via a spacer so as to contact the pressing member. The hardness of the spacer provided between the supporting member and the pressing member is equal to or greater than the hardness of the developer regulating member, and the developer regulating member and the pressing member are held between the supporting member and the pressing member. The hardness of the spacer provided between the members is determined by the developer Is achieved by member is less than the hardness.

According to the second aspect of the present invention,
The above object is achieved in the first aspect by the fact that the developer regulating member is attached to the supporting member with an adhesive.

Further, according to the third invention of the present application, the above object is achieved in the first invention or the second invention, in that the angle between the support member and the pressing member is an acute angle. Is done.

According to the fourth aspect of the present invention,
An object of the present invention is to provide the spacer according to any one of the first to third inventions, wherein a surface of the spacer provided between the developer regulating member and the pressing member on the side of the developer regulating member is uneven. Is achieved by

[0020]

According to the first aspect of the present invention, the hardness of the spacer provided between the support member and the pressing member is equal to or higher than the hardness of the developer regulating member. Even when a spacer having a lower hardness than the developer regulating member is sandwiched between the supporting member and the pressing member, the gap between the supporting member and the pressing member is maintained at a predetermined value. Then, when the low-hardness spacer and the developer regulating member that are in contact with the holding member are sandwiched between the supporting member and the holding member in which the predetermined gap is held, the developer regulating member and the holding member are interposed. Since the hardness of the spacer sandwiched between the pressing members is less than the hardness of the developer regulating member, the spacer collapses faster than the developer regulating member, and alleviates excessive collapse of the developer regulating member, The developer regulating member is held to such an extent that no deformation occurs between the supporting member and the pressing member. Therefore, the developer regulating member is not crushed more than necessary and is kept at a constant pressure, so that a stable image without density unevenness in the longitudinal direction can be obtained.

According to the second aspect of the present invention,
In the first aspect of the invention, since the developer regulating member is attached to the supporting member with an adhesive, the pressing member may be attached using the spacer as described above, and the workability is improved.

Further, according to the third aspect of the present invention, in the first aspect or the second aspect, the angle between the supporting member for holding the developer regulating member and the pressing member is an acute angle. This disperses the force received by the developer regulating member due to the rotation of the developer carrying member, prevents deformation due to the force, and keeps the contact pressure between the developer regulating member and the developer carrying member constant so as to apply to the toner. Tribo is also uniform,
A good image without density unevenness can be obtained.

According to a fourth aspect of the present invention,
In any of the first to third inventions,
By making the surface on the developer regulating member side of the spacer sandwiched between the developer regulating member and the pressing member uneven, the frictional force of the contact surface between the spacer and the developer regulating member is reduced. Enhance
Increase the holding force of the developer regulating member. Thereby, the displacement of the developer regulating member due to an external force or the like is prevented, the contact pressure between the developer regulating member and the developer carrier is always constant, and a good image without density unevenness is obtained.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a photosensitive drum as an image carrier, 8 denotes a developing container, and 5 denotes a magnetic toner as a one-component magnetic developer.
A non-magnetic developing sleeve 3 as a developer carrying body in which a fixed magnet 31 is enclosed is rotatably installed in an opening facing the photosensitive drum 1. On the developing sleeve 3, the layer thickness of the developer is set. The regulating blade 4 is in contact.

According to the present embodiment, the developing sleeve 3 is made of an aluminum pipe having a diameter of 16 mm,
It is rotated in one direction at a peripheral speed of 47 mm / sec. The fixed magnet 31 in the developing sleeve 3 has four magnetic poles N ₁ , S ₁ , N ₂ , and S ₂ having a magnetic flux density of 75 mT alternately arranged.

The toner 5 in the developing container 8 is
The toner is carried on the developing sleeve 3 by the magnetic force of 1 and is regulated by the blade 4 in contact with the developing sleeve 3 to form a toner layer having a predetermined thickness. The toner 5 formed on the toner layer is conveyed to a developing unit facing the photosensitive drum 1 with the rotation of the developing sleeve 3 and is used for developing a latent image on the photosensitive drum 1.

According to the present embodiment, the blade 4 comprises a supporting metal plate 4a as a supporting member and a pressing metal plate 4c as a pressing member.
And an elastic blade 4b as a developer regulating member sandwiched between the supporting metal plate 4a and the pressing member 4c, and a spacer (a) 4d and a spacer (b) 4e. The elastic blade 4b is a rubber member such as urethane, nylon, and silicone. The supporting metal plate 4a and the holding metal plate 4c may be made of metal or a material having rigidity equivalent thereto, and are typically aluminum, stainless steel or the like. The support sheet metal 4a and the elastic blade 4b may be pasted together with an adhesive or the like as a temporary fixing function to improve workability. Spacer (a) 4d is holding metal plate 4c
Is a member that is sandwiched in parallel so as not to incline with respect to the supporting metal plate 4a and pressed down with a constant pressure. The spacer (a) 4d does not have to be attached to the entire area in the longitudinal direction of the blade 4, and may be attached only to a screwing position for fixing the blade 4 to the developing container 8. The spacer (b) 4e is sandwiched between contact portions between the elastic blade 4b and the holding plate 4c.

The spacer (a) 4d has a role of positioning when the supporting plate 4a and the holding plate 4c are sandwiched, and the spacer (b) 4e does not crush the elastic blade 4b too much when sandwiched. There is a role of relaxation.

Here, the relationship between the hardness of the spacer (a) 4d, the hardness of the spacer (b) 4e, and the elastic blade 4b will be described. If the elastic blade 4b is too crushed when sandwiched between the supporting metal plate 4a and the holding metal plate 4c, the elastic blade 4b is bent or deformed, and a uniform contact pressure cannot be obtained. Therefore, in order to prevent the elastic blade 4b from being crushed too much, the spacer (a) 4
The hardness d (Asker C) is a material having a hardness equal to or higher than that of the elastic blade 4b, and the hardness of the spacer (b) 4e is lower than the hardness of the elastic blade 4b. Therefore, when sandwiched between the supporting plate 4a and the holding plate 4c, the distance from the supporting plate 4a to the holding plate 4c is determined to some extent by the width of the harder spacer (a) 4d, and the spacer (b) Since the hardness of the elastic blade 4e is low, the elastic blade 4e is crushed earlier than the elastic blade 4b.

Next, the relationship between the thickness of the spacer (a) 4d and the thickness of the spacer (b) 4e will be described. In order to uniformly sandwich the elastic blade 4b in the blade 4 of the type that sandwiches the elastic blade 4b using only the spacer (a) 4d, the height of the spacer (a) 4d must be equal to the thickness of the elastic blade 4b. Must be the same as However, the height may not match due to the thickness tolerance of the elastic blade 4b and the thickness tolerance of the spacer (a) 4d. In particular, when the thickness of the spacer (a) 4d is larger than the thickness of the elastic blade 4b, the width sandwiched between the supporting metal plate 4a and the holding metal plate 4c is determined by the spacer (a) 4d. Rather than obtaining a high pressure, it becomes difficult to maintain the pressure itself. Therefore,
It is necessary to tighten the tolerance of the thickness of the spacer (a) 4d and the elastic blade 4b. However, in the case of the blade 4 having the configuration of the present embodiment, the spacer (a) 4
Even if d is thicker than the elastic blade 4b, if the thickness when the elastic blade 4b and the spacer (b) 4e are combined as shown in FIG. 2 is larger than the thickness of the spacer (a) 4d, When the spacer (b) 4e is sandwiched between the holding metal plates 4c, the spacer (b) 4e has a low hardness.
Crush to a thickness of 4d. The elastic blade 4b receives a uniform pressure when the spacer (b) 4e is crushed, so that it can be stably held. Therefore, it is not necessary to tighten the thickness tolerance of the elastic blade 4b and the spacer (a) 4d, and the sum of the thicknesses of the elastic blade 4b and the spacer (b) 4e is larger than the thickness of the spacer (a) 4d. It is only necessary to set a tolerance range that increases, which is effective for improving the yield of each member and reducing costs.

This embodiment is constituted by using the following members.

Elastic blade 4b: Urethane rubber Thickness = 1.1 mm Hardness (Asker C) = 50 degrees Spacer (a) 4d: Acrylic resin thickness = 2.0 mm Hardness (Asker C) = 95 degrees Spacer (b) ) 4e: Silicone rubber Thickness = 1.4 mm Hardness (Asker C) = 38 degrees Supporting metal plate 4a: Aluminum thickness = 1.4 mm Pressing metal plate 4c: Aluminum thickness = 1.4 mm

In the present embodiment, the spacer is made of the above-mentioned material. As the material, the spacer (a) 4d is preferably a metal such as aluminum or a plastic such as ABS resin or phenol resin. A member that is hard to be crushed even if it is sandwiched by the holding sheet metal 4c, such as 70 to 100 degrees (Asker C), is suitable.
For rubber, rubber such as polyurethane rubber and acrylic rubber, and sponges such as foamed urethane and foamed EPDM are suitable for hardness of 20 to 60 degrees.

Regarding the thickness of the spacer, the spacer (a) 4d is most preferably from the upper limit of the thickness tolerance of the elastic blade to the thickness obtained by adding 1 to 5 mm to the value. Since the spacer (b) 4e is also thicker as the spacer (a) 4d is thicker, the ratio of the amount of the spacer (b) 4e crushed by the holding sheet metal 4c is smaller than the thickness, and the spacer (b) 4e is crushed. Elastic blade 4b due to variation in amount
There is a merit that the variation of the pressure received is small. However, if the spacer (a) 4d is too thick and the blade 4 becomes too large, the developing device becomes too large, and the blade 4 comes into contact with the photosensitive drum 1.
The above range is desirable.

The thickness of the spacer (b) 4e varies depending on the hardness of the spacer (b) 4e, and cannot be said unconditionally. However, when the screw or the like for fixing the blade 4 to the developing container 8 is tightened. The pressure received by the elastic blade 4b is preferably 50% to 90% of the pressure received by the supporting metal plate 4a.

The blade 4 having such a configuration (FIG. 1)
Is used, the elastic blade 4b is held at an appropriate and uniform pressure, and the elastic blade 4b does not bend or deform in any environment and even after the life of the cartridge is passed. . Therefore, the contact portion with the sleeve can be brought into contact with a constant pressure, so that a stable charge can be contributed to the toner, and a high-quality image with sufficient density can be obtained.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the angle (θ) between the holding plate 4c and the supporting plate 4a is an acute angle in the blade having the structure of the first embodiment.

FIG. 3 is a sectional view of the blade 4 having the structure of the present embodiment. In this embodiment, since the configuration is the same as that of the first embodiment, the above-described effects are obtained.
The following effects can be obtained by making the angle (θ) between c and the supporting metal plate 4a an acute angle.

In FIG. 4, when the developing sleeve 3 comes into contact with the blade 4 and rotates in the direction of arrow R2, the elastic blade 4b receives a force in the direction of arrow A in FIG. The force f is received in the direction of B, and the holding plate 4c tries to open outward with the screw 11 stop position as a fulcrum, so that the elastic blade 4b floats from the supporting plate 4a and the contact pressure decreases. For this force f, the first
In the configuration of the embodiment, as described above, the holding plate 4
Although c does not open even when it receives the force f, when the structure of this embodiment is further used, the force f is set by making the holding plate 4c angle to the support plate 4a as shown in FIG.
Is decomposed into fa and fb. Holding plate 4c is screw 11
The force that tries to open the stop position at the fulcrum is fa,
Since the force f is smaller than the force f, the elastic blade 4b can be more firmly held and stabilized.

In the present embodiment, the holding blade 4c is inclined (θ) with respect to the supporting plate 4a.
Presser plate 4 of spacer (a) 4d having hardness higher than b
The angle of the cross section on the side c is set to θ ° with respect to the side of the supporting metal 4a so that the holding metal 4c can be stably mounted. Since the spacer (b) 4e has a low hardness, the angle on the holding sheet metal side may or may not be set similarly to the spacer (a) 4d.

The angle θ between the holding metal plate 4c and the supporting metal plate 4a may be an acute angle, but if the θ is too large, the mounting of the holding metal plate 4c will not be stable.
It is preferable that 0 ° ≦ θ ≦ 30 °.

As described above, by using the blade 4 having the configuration of the present embodiment, low cost and safety can be achieved.
It is possible to prevent peeling of the elastic blade 4b, suppress a decrease in contact pressure due to durability and the like, and obtain a stable image throughout.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the surface of the spacer (b) 4e on the elastic blade 4b side is made uneven in the blade 4 having the structure of the first embodiment.

FIG. 6 is a sectional view of the spacer (b) of this embodiment. This is one in which the surface on the elastic blade 4b side is made uneven in a stepwise manner.

Elastic blade 4b of spacer (b) 4e
By making the surface on the side uneven, the elastic blade 4b
The frictional force of the contact surface with the elastic blade 4b is increased, and the holding of the elastic blade 4b becomes more stable.

When the developing sleeve 3 comes into contact with the blade 4 as shown in FIG. 7, the elastic blade 4b is bent along the developing sleeve 3, and the length of the arc of the elastic blade 4b on the side of the holding plate 4c ( Since P) is larger than the support metal plate 4a side (Q), the elastic blade is pulled in the direction of the arrow C because the elastic blade tries to return to the original shape. When the developing sleeve 3 rotates as described in the second embodiment, a force acts on the elastic blade 4b in the direction of arrow B as shown in FIG. In the present embodiment, it is possible to suppress the movement of the elastic blade 4b, which tends to move with the above-described force, and to completely fix the elastic blade 4b at the set position.

As other shapes of the surface irregularities of the spacer (b) 4e, those having a hemispherical convex portion are typical. If the other shapes are irregular, the above-described effects can be obtained. However, it is particularly preferable to sandwich the elastic blade 4b with a stepped shape in the longitudinal direction as shown in FIG. 6 to obtain a uniform contact surface with the elastic blade 4b. When the spacer (b) 4e is a flexible member such as a sponge, a material having an uneven surface such as sandpaper may be attached to the surface.

As described above, by using the blade 4 having the configuration of the present embodiment, low cost and safety can be achieved.
A uniform contact pressure can be obtained by stable holding, and a stable image without density unevenness can be obtained.

[0052]

As described above, the first embodiment according to the present application is described.
According to the invention, between the supporting member attached to the developing container and the pressing member facing the supporting member via the spacer, the developer regulating portion is provided together with another spacer that comes into contact with the pressing member. The hardness of the spacer that is sandwiched between the support member and the pressing member is equal to or greater than the hardness of the developer regulating member, and the spacer that is sandwiched between the developer regulating member and the pressing member is Since the hardness is less than the hardness of the member, it is possible to increase the tolerance of the spacer which had to be strict until now, and the developer regulating member is not crushed more than necessary, and the developer regulation is performed at a constant pressure. Since the members can be held, it is possible to obtain a stable image free from density unevenness in the longitudinal direction by the low-cost sandwiching type developer regulating member.

According to the second aspect of the present invention,
In the first aspect, since the developer regulating member is attached to the supporting member with an adhesive, the workability of the above-described sandwiching can be improved.

Further, according to the third aspect of the present invention, in the first aspect or the second aspect, the angle between the supporting member and the pressing member is made acute,
The developer regulating member can be prevented from being deformed by the force received from the developer carrier, the contact pressure between the developer regulating member and the developer carrier is always constant, and the tribo applied to the toner is also uniform. Therefore, a good image without density unevenness can be obtained.

According to the fourth invention of the present application,
In any of the first to third inventions,
By making the surface on the developer regulating member side of the spacer provided between the developer regulating member and the pressing member uneven, the displacement of the developer regulating member due to an external force or the like received on the developer regulating member is prevented, The contact pressure between the developer regulating member and the developer carrier is always constant, and a good image without density unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing thicknesses of an elastic blade and a spacer according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a blade according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a force received by an elastic blade when a developing sleeve rotates.

FIG. 5 is a schematic diagram showing a force applied to an elastic blade according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a shape of a spacer according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a force received by an elastic blade when a developing sleeve is in contact with the developing blade.

FIG. 8 is a sectional view showing an image forming apparatus showing a conventional example.

FIG. 9 is a diagram for explaining a problem of a blade when a spacer is used.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum (image carrier) 3 developing sleeve (developer carrier) 4a supporting metal plate (supporting member) 4b elastic blade (developer regulating member) 4c pressing metal plate (pressing member) 4d, 4e spacer 5 toner (developing) 8) Developing container

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References Jiyo Sho 62-9275 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) G03G 15/08 G03G 21/10

Claims (4)

(57) [Claims] 1. A developer container for storing a developer, a developer carrier for carrying and transporting the developer, and an elastic developer regulating member disposed such that a free end thereof is in contact with the developer carrier. While forming a thin layer of developer on the developer carrier by the developer regulating member, the developer is transported to a developing unit facing the image carrier, and the formed latent image is developed. In the developing device for visualizing, the developer regulating member has an end opposite to the free end, a supporting member attached to the developing container, and a pressing member opposed to the supporting member via a spacer. Between the supporting member and the pressing member, and the hardness of the spacer provided between the supporting member and the pressing member is controlled by the developer regulation. The hardness of the member is higher than that of the developer regulating member and the pressing member. A developing device, wherein the hardness of the spacer is less than the hardness of the developer regulating member. 2. The developing device according to claim 1, wherein the developer regulating member is attached to the supporting member with an adhesive. 3. The developing device according to claim 2, wherein the angle between the support member and the pressing member is an acute angle. 4. The developing device according to claim 1, wherein a surface of the spacer provided between the developer regulating member and the pressing member on the side of the developer regulating member is uneven.