JPH11160973A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unsatisfactory image-quality, resulting from unsatisfactory feed of a development bias, and electric wave noise by securely feeding the development bias to a developing unit. SOLUTION: At the side of the developing unit 18 is a power receiving part 24, into which a power-receiving member 32 is freely slidably inserted. The developing unit 18 is provided with a metal plate 34 which contacts the shaft 22 of a magnet roll 20. A compression coil spring 36 is inserted into the projection 26 of the power receiving part 24, to energize the power receiving member 32. A high-voltage power feed part 38 to which a contact plate 40 is mounted in contact with the power receiving member 32 is provided in the direction of the side of a rotating body 16, and a high-voltage power source is connected to the contact plate 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for an image forming apparatus such as a printer, a copying machine, or a facsimile which can use a developing device without replacement until the life of the device and can form a toner image on recording paper. More particularly, the present invention relates to a rotary developing device having a developing bias power supply mechanism.

[0002]

2. Description of the Related Art Generally, a rotary developing device is used in a full-color printer and a full-color copying machine. In this rotary developing device, when a developing device of a color to be developed is opposed to a photoconductor, a developing bias is supplied to the developing device to develop a latent image on the photoconductor.

As a method of supplying a developing bias to the developing device, a power supply member (for example, stainless steel) for supplying power is provided on a main body side of an apparatus such as a full-color printer and a full-color copying machine, and the power supply member is opposed to the power supply member. In general, a conductive power supply member (for example, stainless steel or the like) is provided at a position where the toner is supplied, and the two members are brought into contact at the developing position.

A common feature of these methods is that both the power supply member on the apparatus main body side and the power supply member on the developing device side use metal-based materials.

[0005]

However, in the above-described power supply mechanism for supplying the developing bias, since the power supply members on the apparatus main body side and the developing device side are each made of metal, the following problems occur. .

The first problem is that a discharge product adheres to the contact portion due to sliding of the contact portion during the supply of the developing bias or sliding of the contact portion due to rotation of the developing device. There is a possibility that the power supply of the developing bias is hindered and a power supply failure of the developing bias occurs.

As a second problem, the contact portion slides due to the rotation of the developing device. At this time, sliding noise (noise) increases due to sliding of the metals, and in some cases, abnormal noise occurs. There is a fear.

The present invention has been made in view of the inconveniences of the prior art, and reliably supplies a developing bias to a developing device to prevent poor image quality due to insufficient supplying of a developing bias and generation of radio noise. Another object of the present invention is to provide a developing device capable of reducing sliding noise.

[0009]

According to a first aspect of the present invention, there is provided a developing device for supplying a developing bias from the main assembly side to the developing device while rotating the developing unit relative to the main assembly. A power supply member and a power supply member on the side of the developing device in contact with the power supply member are arranged on the side surface, which is the end of the developing device, along a turning axis for turning the developing device. The center of the developing roll of the developing device is arranged in the inside.

In the developing device according to the second aspect of the present invention, a developing bias is supplied from the device main body to the developing device while rotating the developing device relative to the apparatus main body, and the developing device is sequentially opposed to the photosensitive member to form an image. In the developing device, at least one of the power supply member on the apparatus main body side and the power supply member on the developing device side that comes into contact therewith is formed in a convex shape with a conductive resin.

According to a third aspect of the present invention, in the developing device of the second aspect, at least one of the power supply member on the apparatus main body side and the power supply member on the developing device contacting the main body has elasticity. And

According to a fourth aspect of the present invention, in the developing device of the second aspect, the power supply member has a surface resistance such that a voltage drop of the power supply member is 1% or less at an applied voltage of a developing bias to be used. It is characterized by having done.

According to a fifth aspect of the present invention, in the developing device according to the second aspect, the forming temperature of the conductive resin when forming the power supply member ranges from 60 ° C. to a temperature at which the conductive resin can flow. It is characterized by having.

The operation of the developing device according to claim 1 will be described below. The developing device according to the present invention supplies a developing bias from the device main body to the developing device while rotating the developing device with respect to the device main body. The members are respectively arranged on the side surfaces which are the ends of the developing device along the pivot axis for pivoting the developing device. Further, the center of the developing roll of the developing device was arranged in the locus of the rotation of the developing device around the rotation axis.

That is, the developing device is a rotary developing device in which the developing device rotates around a rotation axis, and a power supply position which is a position of the power supply member on the developing device side when the power is supplied by contacting the power supply member on the device main body side. Is arranged in the vicinity of the rotation center which is the pivot of the developing device.

On the other hand, in the case of the rotary developing device, the developing bias is applied not only at the time of development but also at a predetermined timing even when the developing device is opposed to the photosensitive member and even when the developing device is separated from the photosensitive member. Supply is required.

More specifically, when it is necessary to supply a developing bias to the developing position within a range of, for example, ± 25 degrees around the rotation axis of the rotary developing device, a sliding distance between the power supply members is required. And the wear on the surface of the power supply member increases. In the conventional developing device, since the power supply members are disposed on the outer peripheral surface side of the rotary developing device, the sliding distance is further increased.

According to the structure of the present invention, since the power supply position is located near the rotation center of the rotary developing device, the sliding distance between the power supply members is minimized. As a result, the developing bias is reliably supplied to the developing device, and not only the image quality defect due to the insufficient supplying of the developing bias and the occurrence of radio noise can be prevented, but also the wear of the surface of the power supply member is minimized, and It is possible to achieve downsizing of parts and downsizing of an apparatus such as an image forming apparatus.

The operation of the developing device according to claim 2 will be described below. In the present invention, at least one of the power supply member on the apparatus main body side and the power supply member on the developing device side in contact therewith is formed in a convex shape with a conductive resin.

That is, in a rotary developing device in which the power supply member for supplying the developing bias with the rotation is rubbed, with such a configuration, the convex contact portion of the conductive resin is rubbed with the mating member. Wears it little by little, so that a new surface state contact always comes into contact. As a result, it is possible to always supply a stable supply of the developing bias, and it is possible to prevent image quality defects and radio noise from occurring.

Further, the power supply member on the apparatus main body side and the power supply member on the developing device side slide with each other. At this time, the sliding movement (noise) does not increase because the metals do not slide.

Also, since at least one of the power supply members is formed in a convex shape, there is only one contact point for supplying the developing bias. That is, when a plurality of contacts are provided, contact of one of the contacts may become unstable. In this case, a discharge occurs at the contact, causing rapid wear in the conductive resin. In addition, there is a problem that a discharge product adheres due to this discharge to cause a power supply failure or to cause radio noise.

On the other hand, according to the configuration of the present invention, since the power supply member is formed in a convex shape and the contact point is one point, reliable contact can be ensured, and stable power supply can be performed.

The operation of the developing device according to claim 3 will be described below. The present claim also has the same configuration as that of claim 2, and duplicate description will be omitted. However, in the present invention, at least one of the power supply member on the device main body side and the power supply member on the developing device side that comes into contact with the power supply member has elasticity.

In a rotary developing device, since the device main body and the developing device usually have many components, the contact portion between the power supplying member on the device main body side and the power supplying member on the developing device side may be changed due to variation in component dimensions. It was very difficult to keep the bite amount (contact pressure) constant.

According to the structure of the present invention, the contact portion can be reliably contacted by the elasticity, and the variation in the contact pressure can be made very small. As a result, the contact pressure can be set lower, and as a result, the wear of the contact portion of the conductive resin can be minimized, and the life of the device can be extended.

The operation of the developing device according to claim 4 will be described below. The present claim also has the same configuration as that of claim 2, and duplicate description will be omitted. However, in the present invention, the upper limit of the surface resistance of the power supply member made of the conductive resin is defined.

Normally, carbon fibers are exposed on the surface of the conductive resin, and conductivity is secured by using this portion as a contact portion. In general injection molding, for example, a film is formed on the surface. As a result, the carbon fibers may not be exposed on the surface. In such a case, the surface resistance becomes extremely high, and the voltage of the developing bias is reduced, resulting in poor image quality.

On the other hand, it is extremely difficult to aim at a resistance value of 0 with a general conductive resin in which carbon fibers are mixed in a resin base material, because of its physical properties. Therefore, if the upper limit of the surface resistance of the power supply member made of the conductive resin is defined as in the present invention, the upper limit of the surface resistance can be grasped in accordance with various use conditions, and the mass productivity of the conductive resin can be secured.

The operation of the developing device according to claim 5 will be described below. The present claim also has the same configuration as that of claim 2, and duplicate description will be omitted. However, in the present invention, the forming temperature of the conductive resin when forming the power supply member is set to 60 ° C.
To the temperature at which the conductive resin can flow.

Therefore, by performing injection molding in a temperature range of 60 ° C. or less and a temperature at which the conductive resin can flow, a power supply member made of a conductive resin can be easily manufactured. As a result, it is possible to obtain a developing device that reliably supplies the developing bias to the developing device by using the power supply member, prevents image quality defects due to insufficient supply of the developing bias, and prevents the occurrence of radio noise and reduces the sliding noise. Becomes possible.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the developing device of the present invention will be described with reference to FIGS.

An image forming apparatus such as a printer, a copying machine, or a facsimile, which constitutes the apparatus main body, incorporates the developing device 10 according to one embodiment of the present invention. Further, as shown in FIGS. 1 to 3, the developing device 10 includes a photosensitive drum 12, and a stepping motor (not shown) rotates around the rotation axis G beside the photosensitive drum 12 in FIG. A rotating body 16 that is rotated in the CW direction is provided. The rotating body 16 includes the developing device 1
8C, M, Y, and B are mounted, and the developing devices 18C, M, Y, and B are turned around the turning axis G as the rotating body 16 rotates.

The developing device 18C has a C (cyan) developer in which a toner and a carrier are premixed, and the developing device 18M has an M (magenta) developer in which a toner and a carrier are premixed. However, in the developing device 18Y, a Y (yellow) developer in which a toner and a carrier are premixed, and in a developing device 18B, a B (black) developer in which a toner and a carrier are premixed, respectively Is housed.

As shown in FIG. 2, the developing device 18 is provided with a rotatable magnet roll 20 as a developing roll. The magnet roll 20 is rotated by a gear mechanism (not shown) provided on the shaft portion 22. It has become.
The magnet roll 20 forms a magnetic brush by adsorbing a carrier contained in the developer by a magnetic force, and supplies the toner adsorbed to the carrier to the photosensitive drum 12. As a result, the electrostatic latent image is visualized on the photosensitive drum 12.

As shown in FIG. 2, on the side surface of the developing device 18, a power receiving section 24 as a power supply member on the developing device 18 side is provided.

The power receiving section 24 has a protruding section 26 integrally protruding from one end of the developing device 18. The protrusion 26
A hole 28 having a constant diameter is formed from the inside to the outside of the developing device 18, and the hole 28 is provided with a step 30 on the tip side of the protruding portion 26.

A power receiving member 32 having a hemispherical tip 32A is slidably inserted into the hole 28. On the side opposite to the end 32A side of the power receiving member 32, a step portion 3 is provided.
Flange 32B so as to engage with
Are formed.

On the other hand, the power receiving member 32 is formed of a conductive resin by injection molding in a convex shape, and has such a surface that the voltage drop of the power receiving member 32 is 1% or less by the applied voltage of the developing bias to be used. The power receiving member 32 has a resistance.

The developing device 18 is provided with a metal plate 34 which comes into contact with the shaft portion 22 of the magnet roll 20, and a metal compression coil spring 36 is inserted into the hole 28 of the projecting portion 26. Have been. The compression coil spring 36 is provided between the power receiving member 32 and the metal plate 34 in a compressed state by a predetermined amount.
The power receiving member 32 is urged in a direction to protrude from the power receiving member 32. The metal compression coil spring 36 is connected to the shaft 2.
2 and the metal plate 34, the magnet roll 20 and the power receiving member 32 are electrically connected.

As shown in FIG. 1, these power receiving sections 24 are arranged at 90 ° intervals in the circumferential direction and at the same distance from the rotation axis of the rotating body 16, and are shown in FIGS. 1 to 3. As described above, the high voltage power supply section 38 which is a power supply member on the apparatus main body side is provided on the side of the rotating body 16.

The high-voltage power supply section 38 is a leaf spring made of a metal (stainless steel or the like) plate arranged so as to be elastically deformed along the axial direction (arrow A direction) of the rotating shaft G of the rotating body 16. A plate 40 is attached. The contact plate 40 is set to have such a length that the rotating body 16 rotates by 50 ° until the power receiving member 32 comes into contact with the contact plate 40 and then separates.
The spring stroke L is set to be 2.5 mm.

Further, the developing device 10 includes a high-voltage power supply (not shown) for applying a bias voltage to the magnet roll 20, and the high-voltage power supply is connected to the contact plate 40.

Next, the operation of the developing device according to this embodiment will be described. As is well known, the photosensitive drum 12 is charged by a charging roller and is exposed to a laser beam as a writing element to form an electrostatic latent image. The electrostatic latent image is stored in a magnet roll 20 of a developing device 18C containing a C (cyan) developer, a magnet roll 20 of a developing device 18M containing a M (magenta) developer, and Y (yellow). 3), the magnet roll 20 of the developing unit 18Y containing the developer, and the magnet roll 20 of the developing unit 18B containing the developer of B (black) sequentially face the photosensitive drum 12, and are visualized in full color. You.

In the present embodiment, when the rotating body 16 is rotated by the stepping motor, as shown in FIG. 1, a developing device 18 for performing development first (for example, a developing device 18C containing a developer of C (cyan)) is used. ) Contacts the contact plate 40.

Further, the rotating body 16 rotates by 50 ° until the power receiving member 32 comes into contact with the contact plate 40 and then separates. When the power receiving member 32 comes into contact with the contact plate 40, the high voltage power supply is turned on.

When the high-voltage power supply is turned on, the magnet roll 2
0, a bias voltage is applied, and the toner in the developing device 18C is attracted to the electrostatic latent image portion on the photosensitive drum 12 by a potential difference between the bias voltage and the electrostatic latent image portion formed on the photosensitive drum 12, Thereby, development of the electrostatic latent image is performed.

In the developing device 10 of the present embodiment,
The high-voltage power supply unit 38 and the power receiving unit 24 on the side of the developing device 18 that comes into contact with the high-voltage power supplying unit 38 are arranged on the side surfaces that are the ends of the developing device 10 along the turning axis G that rotates the developing device 18.

Further, as shown in FIG.
The center P of the magnet roll 20 of each developing device 18 is arranged in a locus around which the rotating body 16 of the developing device 10 is rotated, and the power receiving member 32 of each power receiving unit 24 is formed of a conductive resin in a convex shape. Is formed.

That is, the developing device 10 is a rotary developing device in which the developing device 18 rotates around the rotation axis G,
Receiving unit 24 on the side of developing device 18 when power is supplied by contact with
Is set to the turning axis G of the developing device 10.
In the vicinity of the rotation center.

Therefore, according to the present embodiment, since the power supply position is arranged near the rotation center of the rotary developing device, the sliding distance between the power receiving unit 24 and the high voltage power supply unit 38 is minimized. . As a result, the developing bias can be reliably supplied to the developing device 18, and not only the image quality failure due to the insufficient supply of the developing bias and the occurrence of radio noise can be prevented, but also the wear of the surface of the power receiving member 32 can be reduced. In addition, downsizing of components and downsizing of an apparatus such as an image forming apparatus can be achieved.

On the other hand, since the power receiving member 32 is formed in a convex shape with the conductive resin, the convex contact portion of the conductive resin wears little by little by rubbing with the mating member, and the contact having a new surface state is always in contact. Will do. As a result, in combination with the above, stable and stable power supply of the developing bias can be performed more reliably, and poor image quality and generation of radio noise can be more reliably prevented.

Further, the high-voltage power supply section 38 and the power receiving section 24 on the side of the developing device 18 slide with each other. At this time, since the metal does not slide with each other, the sliding noise (noise) does not increase.

On the other hand, in the present embodiment, the high-voltage power supply section 38 and the power receiving section 24 on the side of the developing device 18 have elasticity by the compression coil spring 36 and the contact plate 40, respectively. The spring stroke L of 2.
It is set to be 5 mm.

Therefore, the contact portions can be reliably contacted by the elasticity, and the variation in the contact pressure can be extremely reduced. As a result, the contact pressure can be set lower. As a result, in combination with the above-described arrangement of the power supply position, the wear of the contact portion of the power receiving member 32 formed of the conductive resin can be minimized, and the life of the device can be prolonged. it can.

On the other hand, the spring stroke L, which is the amount of bite between the power receiving member 32 and the contact plate 40, is specifically 2.5 m
The reason why m was set is that the spring stroke L was set to 0.
It has been found that a small amount of about 3 mm can sufficiently prevent poor image quality and generation of radio noise.
This is because it has been found that the amount of wear is also sufficiently small.

Further, in this embodiment, the power receiving member 32 has a surface resistance such that the voltage drop of the power receiving member 32 is 1% or less at the applied voltage of the developing bias to be used. That is, if the upper limit of the surface resistance of the power receiving member 32 by the conductive resin is defined as in the present embodiment, the upper limit of the surface resistance can be grasped in accordance with various use conditions, and the mass productivity of the conductive resin can be secured. it can.

In the present embodiment, the forming temperature of the conductive resin when forming the power receiving member 32 is set in a range from 60 ° C. to a temperature at which the conductive resin can flow.

Accordingly, by performing injection molding in a temperature range of 60 ° C. or less and a temperature range at which the conductive resin can flow, the power receiving member 32 made of the conductive resin can be easily manufactured. became.

In the present embodiment, the developing is performed by continuously rotating the rotating body 16, but the developing may be performed by temporarily stopping the rotating body 16.

In the present embodiment, the power receiving member 32 on the developing device 18 side is made of a conductive resin. However, the power receiving member 32 may be made of metal and the member on the high voltage power supply section 38 side may be made of a conductive resin. . Further, as the conductive resin used in the present embodiment, POM or nylon containing carbon fiber can be considered, but other resin materials may be used.

[0062]

Since the developing device of the present invention has the above-mentioned structure, the developing bias is reliably supplied to the developing device, and the image quality defect and the radio noise caused by the insufficient supplying of the developing bias can be prevented. It has an excellent effect that dynamic sounds can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a developing device according to an embodiment.

FIG. 2 is a front view of a main part of the developing device according to the embodiment.

FIG. 3 is a view taken in the direction of arrow 3-3 in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Developing device 12 Photoreceptor drum 18 Developing device 24 Power receiving part 32 Power receiving member 38 High voltage power supply part 40 Contact plate

Claims (5)

[Claims] 1. A developing device for supplying a developing bias to a developing device from an apparatus main body while rotating the developing device with respect to the apparatus main body. The members are respectively arranged on the side surfaces which are the ends of the developing device along the turning axis for turning the developing device, and the center of the developing roll of the developing device is disposed in the locus of rotating the developing device around the turning axis. A developing device, characterized in that: 2. A developing device for supplying a developing bias from the device main body to the developing device while rotating the developing device with respect to the device main body, and sequentially forming the developing device so as to face the photosensitive member, thereby forming an image. A developing device, wherein at least one of the power supply member on the apparatus main body side and the power supply member on the developing device side in contact with the main body is formed in a convex shape with a conductive resin. 3. The developing device according to claim 2, wherein at least one of the power supply member on the side of the apparatus main body and the power supply member on the side of the developing device in contact with the main body has elasticity. 4. The developing device according to claim 2, wherein the power supply member has a surface resistance such that a voltage drop of the power supply member is 1% or less at an applied voltage of a developing bias to be used. 5. The developing device according to claim 2, wherein a molding temperature of the conductive resin when forming the power supply member is in a range from 60 ° C. to a temperature at which the conductive resin can flow. .