JPH06348123A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] By reducing the sliding force between the drive-side journal of the developing roller drive shaft and the inner surface of the bearing when the developing unit is driven, good image quality without the occurrence of jitter images and the like can be obtained. Reduce bearing wear and the load on the drive unit of the copier body. [Structure] A leaf spring 10 fixed to a guide rail 5 by pressing portions of a driving side cam 9a and a driven side cam 9b which are rotated after the developing unit 1 is inserted onto a guide rail 5 in a main body 100 of a copying machine. Press the developing roller 3
Drive side bearing 4a and driven side bearing 4b of the photosensitive drum 6
In a copying machine in which the developing roller 3 is positioned by pressing the supporting side plates 6a and 6b of 0, the length 1 from the rotation center of the drive side cam 9a to the tip of the pressing portion is set to the rotation center of the driven side cam 9b. It should be shorter than the length L to the tip of the pressing part (conventional length). Further, a leaf spring 17 or the like that biases only the drive side of the guide rail 5 in the direction (arrow D) away from the photoconductor unit 6 may be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile and a printer, and more specifically, it is provided with a developing device having a developer carrying member arranged in contact with or in close proximity to the image carrying member. Image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, after the developing device is inserted into the guide member in the main body of the apparatus, the guide member is rotated by the pressing portions of the driving side cam and the driven side cam which are rotated to the pressing position. It is known that the two-step operation procedure of moving the guide member on which the developing device is mounted to the image carrier side by pressing the plate-shaped spring member attached to the image forming device is known. Further, in order to minimize the bite amount between the developer carrying member and the image carrying member and the variation (gap tolerance) of the gap, the bearing of the developer carrying member is abutted against the supporting side plate of the image carrying member for positioning. Is often used.

[0003]

However, in positioning the developer carrier in the image forming apparatus, the bearing of the developer carrier is abutted against the supporting side plate of the image carrier, so that the drive shaft of the developer carrier. The sliding force between the journal and the inner surface of the bearing increases, resulting in an increase in driving torque. In particular, when the developing device is driven, the driving force transmitted from the driving gear causes the driving-side bearing of the developer carrier to come into contact with the supporting side plate of the image carrier more strongly than to the driven side. As a result, the drive torque of the developing device may increase, a jitter image may be generated, and good image quality may not be obtained, the bearing may be worn, or a large load may be applied to the drive unit of the main body of the device. .

The present invention has been made in view of the above problems, and an object of the present invention is to obtain good image quality without generation of a jitter image, bearing wear, and drive portion of the apparatus main body. An object is to provide an image forming apparatus that can reduce the load.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 has a developer carrier arranged in contact with or in close proximity to the image carrier, and has a main body in an image forming apparatus. On the other hand, a developing device that can be freely attached and detached and an urging means that urges the developing device in the image forming apparatus to the image carrier side as necessary are provided, and the developing device is inserted into the main body of the image forming apparatus. After that, the driving side bearing and the driven side bearing of the developer bearing member are brought into pressure contact with the image bearing member or its supporting side plate by the urging means to position the developer bearing member, The pressing force of the driving side bearing to the image carrier or its supporting side plate when the developing device is driven is substantially the same as the pressing force of the driven side bearing to the image carrier or its supporting side plate. It is characterized by being configured as follows.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, there is provided a guide member for guiding the developing device while placing the developing device when the developing device is inserted into the main body of the image forming device. , A plate-like spring member mounted on the guide member on the driving side and the driven side of the rotating shaft of the developer carrying member as the urging means, and freely rotatable to press the plate-like spring member as necessary. A driving side cam and a driven side cam, wherein the length from the rotation center of the driving side cam to the tip of the pressing portion and the length from the rotation center of the driven side cam to the tip of the pressing portion are different. To do.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, a guide member is provided for guiding the developing device while mounting the developing device when the developing device is inserted into the main body of the image forming apparatus. A drive-side biasing unit that biases only the drive-side end of the guide member corresponding to the drive unit of the developer carrier in a direction away from or toward the image carrier. It is what

[0008]

According to the invention of claim 1, the urging means comprises:
The pressure contact force of the drive side bearing to the image carrier or its supporting side plate when the developing device is driven is configured to be substantially the same as the pressure contact force of the driven side bearing to the image carrier or its supporting side plate. . As a result, when the developer bearing member receives a force from the drive system toward the image bearing member when the developing device is driven, the sliding force between the journal on the driving side of the developer bearing member driving shaft and the inner surface of the bearing is smaller than the conventional one. can do.

According to the second aspect of the present invention, the length from the rotation center of the drive side cam to the tip of the pressing portion is different from the length from the rotation center of the driven side cam to the tip of the pressing portion. For example, when the developer carrying member receives a force from the drive system toward the image carrying member side when the developing device is driven, the length from the rotation center of the driving side cam to the tip of the pressing portion is calculated from the rotation center of the driven side cam. It is shorter than the length to the tip of the pressing part. As a result, after the developing device is inserted into the main body of the apparatus, the plate-shaped spring member is pressed by the pressing portions of the driving side cam and the driven side cam which are rotated to the pressing position, and the driving side bearing and the driven side of the developer carrying member are pressed. When the bearing is pressed against the supporting side plate of the image bearing member, the pressing force of the driving side cam on the plate-shaped spring member becomes smaller than the pressing force of the driven side cam, and before the developing device is driven, the above-mentioned guide is formed by the plate-shaped spring member. The force of the member toward the image carrier on the drive side and the pressure contact force of the drive side bearing to the image carrier or its supporting side plate are substantially zero or smaller than those on the driven side. Therefore, the pressure contact force of the drive side bearing to the image carrier or its supporting side plate when the developing device is driven can be made substantially the same as the pressure contact force of the driven side bearing to the image carrier or its supporting side plate. The sliding force between the journal on the drive side of the carrier drive shaft and the inner surface of the bearing can be made smaller than before.

According to the third aspect of the present invention, the drive side biasing means biases only the drive side end portion of the guide member corresponding to the drive portion of the developer carrying member toward or away from the image carrying member. Means are provided. For example, when the developer carrying member receives a force from the driving system toward the image carrying member side when the developing device is driven, only the driving side end of the guide member is moved relative to the image carrying member by the driving side biasing means. Energize away. As a result, the plate-shaped spring member is pressed by the pressing portions of the driving-side cam and the driven-side cam that are rotated to the pressing position after the developing device is inserted into the device body, and the driving-side bearing and the driven member of the developer carrier are driven. When the side bearing is brought into pressure contact with the supporting side plate of the image bearing member, the pressure contact force of the driving side bearing with respect to the image bearing member or its supporting side plate becomes substantially zero or smaller than that on the driven side.
Therefore, the pressure contact force of the drive side bearing to the image carrier or its supporting side plate when the developing device is driven can be made substantially the same as the pressure contact force of the driven side bearing to the image carrier or its supporting side plate. The sliding force between the journal on the drive side of the carrier drive shaft and the inner surface of the bearing can be made smaller than before.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. The configuration of each device other than the developing device of the copying machine and the image forming operation are the same as those in the conventional art, and thus the description thereof is omitted. FIG. 1 is a perspective view of a developing unit 1 as a developing device used in a copying machine according to this embodiment.
Supporting side plates 2a, 2 on the driving side and the driven side of the developing unit 1
A drive shaft of a developing roller 3 as a developer carrying member is rotatably supported on b. Further, a journal is formed on an extending portion of the drive shaft 3a of the developing roller 3 extending outside the support side plates 2a and 2b, and a drive side bearing 4a and a driven side bearing 4b are attached to each journal. .

The developing unit 1 can be mounted in the main body of the copying machine or removed from the main body of the copying machine as required. When mounting the developing unit 1 in the copying machine main body 100, as shown in FIG. 2, the front cover 101 of the copying machine main body 100 is opened, and the developing unit 1 is inserted from the direction of arrow A while holding the handle 1a. To do. At this time, the developing unit 1 is inserted while being placed on the guide rail 5 as a guide member provided inside the copying machine main body 100.

FIG. 3 is a perspective view showing a positional relationship between the developing unit 1 after the developing unit is inserted and the photosensitive unit 6 having a photosensitive belt as an image carrier disposed therein.
After inserting the developing unit 1 onto the guide rail 5, the manual lever 8 attached to the user side end of the lever rotation shaft 7 rotatably attached to the copying machine main body 100 is rotated in the direction of arrow B. Thus, the drive side cam 9a and the driven side cam 9b fixed to the driving side (back side) and the driven side (front side) of the lever rotation shaft 7 are plate-like spring members fixed to the guide rails 5. The spring 10 is pressed to move the guide rail 5 and the developing unit 1 mounted thereon in the direction of the photoconductor unit 20 (arrow C). At this time, as shown in FIG. 4, the driving side bearings 4a and the passive side bearings 4b at both ends of the developing roller 3 are pressed against the supporting side plates 6a and 6b of the photoconductor belt of the photoconductor unit 6, and the developing roller 3 Positioning is performed with respect to the photoconductor belt.

FIG. 5A is a perspective view showing a detailed structure of the guide rail 5 and its periphery, and FIG. 5B is a front view of the guide rail 5. The pair of pins 5a formed on the back side of the guide rail 5 are supported by the supporting long holes 102a of the rear plate 102 of the copying machine main body, and the supporting long holes 5b on the front side surface of the guide rail 5 are formed on the copying machine main body. The tip screwed to the front plate 103 is supported by a pin-shaped screw 11, and the guide rail 5 is movable in both directions of arrows C and D. In addition, a spring 13 is stretched between a pin 12 attached to the front side surface and the rear side surface of the guide rail 5 and a pin 104 attached to the rear side plate 102 and the front side plate 103 of the copying machine main body, and a guide is provided. The rail 5 is biased in the direction of arrow D. In order to move the guide rail 5 in the direction of arrow C, the manual lever 8 may be rotated around the rotation axis E in the direction of arrow B. As a result, the tips of the pressing portions of the driving side cam 9a and the driven side cam press the leaf spring 10 fixed to the guide rail 5, and the restoring force of the elastically deformed leaf spring 10 is greater than the urging force of the spring 13 in the direction of arrow D. As the size of the developing unit 1 increases, the guide rail 5 moves in the direction of arrow C, and the developing unit 1 on the guide rail 5 moves.
The driving side bearing 4a and the passive side bearing 4b at both ends of the developing roller 3 are pressed against the supporting side plates 6a and 6b of the photoconductor belt of the photoconductor unit 6 to position the developing roller 3 with respect to the photoconductor belt.

However, in positioning the developing roller 3, since the bearings 4a and 4b of the developing roller 3 are abutted against the supporting side plates 6a and 6b of the photosensitive belt, the journal of the drive shaft 3a of the developing roller 3 and the bearing 4a, The sliding force with the inner surface of 4b increases, and the drive torque increases. In particular, when the developing unit 1 is driven, the driving side bearing 4a of the developing roller 3 causes the supporting side plate 6a of the photoconductor belt to move more than the driven side bearing 4b due to the driving force transmitted from the driving side gear portion. Since it strongly contacts the 6b, the driving torque of the developing unit 1 increases, a jitter image is generated and a good image quality cannot be obtained, the bearing is worn,
Alternatively, there is a fear that a large load is applied to the drive unit of the copying machine body.

Therefore, in this embodiment, as shown in FIG. 6, the length 1 from the center of rotation of the driving cam 9a to the tip of the pressing portion is equal to the length from the center of rotation of the driven cam 9b to the tip of the pressing portion. It is shorter than L (conventional length). As a result, as shown in FIG. 7, the pressing force f ₁ of the drive side cam 9a against the plate spring 10 becomes smaller than the pressing force f _{2 of} the driven side cam 9b against the plate spring 10 and the driving side of the developing roller 3 is driven. Bearing 4a
Since the pressure contact force of the photosensitive belt 60 to the support side plate 6a is substantially zero or smaller than that on the driven side, the sliding of the journal on the drive side of the developing roller drive shaft 3a and the inner surface of the bearing 4a when the developing unit 1 is driven. Power can be reduced. Therefore, it is possible to obtain good image quality without the occurrence of jitter images, and to reduce bearing wear and the load on the drive unit of the copying machine main body.

The length L from the rotation center of the driven cam 9b to the tip of the pressing portion satisfies P <f ₂ in order to reliably position the developing roller 3 as shown in FIG. 8 (a). Is set to. Here, P is a tensile force by the spring 13 for separating the guide rail 5 from the photoconductor unit 6.

When the length l from the center of rotation of the drive side cam 9a to the tip of the pressing portion is set so as to satisfy f ₁ <P, as shown in FIG.
Before the driving of the photo bearing belt 4a and the photoconductor belt 60.
There is a case where a gap t is formed between the developing roller 3 and the supporting side plate 6a and the positioning of the developing roller 3 is incomplete. However, with the gap t generated, the main motor 1 of FIG.
4 is turned on, and the developing unit 1 is driven through the main body drive gear 15.
When the side drive gear 16 is driven, as shown in FIG. 7, a force F that moves the developing unit 1 toward the photoconductor unit 6 is generated. Here, when the pressure angle of the gear is α, the horizontal force is represented by Fcosα. Therefore, the driving side bearing 4a is also caused by the force Fcosα generated by the meshing of the teeth of the gears 15 and 16 even on the driving side where the positioning is incomplete.
The outer surface of is contacted with the supporting side plate 6a, and the target positioning is performed. The condition at this time is Fcos α + f ₁ > P.

In the above embodiment, the length l from the center of rotation of the driving cam 9a to the tip of the pressing portion is defined as the driven cam 9a.
Although it is shorter than the length L (conventional length) from the rotation center of b to the tip of the pressing portion, instead of this, the guide rail 5
A drive-side biasing unit that biases only the drive side in the direction (arrow D) away from the photoconductor unit 6 may be provided. FIG. 10 shows an example of a specific configuration of the drive side biasing means. A hole 102b is formed in the rear plate 102 of the main body of the copying machine, and a cut / bend portion 102c is formed in the hole 102b on the side of the photoconductor unit 6. On the other hand, a leaf spring 17 is attached to the inner surface of the guide rail 5 on the side of the photoconductor unit 6. Then, when the guide rail 5 is moved to the photoconductor unit 6 side, the leaf spring 17 moves in the hole 102b and comes into contact with the cut and bent portion 102c. At this time, T
The leaf spring 17 is configured so that the relationship of + P> f ₁ and (P <f ₁ ) is established (see FIG. 11). Here, the force T is
This is a force that acts on the drive side of the guide rail 5 in the direction away from the photoconductor unit 6 when the leaf spring 17 contacts the cut / bend portion 102c. Further, in this configuration, the length l of the driving side cam 9a and the length L of the driven side cam 9b are the same length, and the pressing force f of the driving side cam 9a against the leaf spring 10 is f.
₁ is substantially the same as the pressing force f ₂ of the driven cam 9b against the leaf spring 10.

With the configuration according to the above modification, the drive side bearing 4a of the developing roller 3 and the support side plate 6 of the photosensitive belt 60 are provided.
Since the pressure contact force to a is substantially zero or smaller than that on the driven side, it is possible to reduce the sliding force between the drive-side journal of the developing roller drive shaft 3a and the inner surface of the bearing 4a when the developing unit 1 is driven. Therefore, it is possible to obtain good image quality without the occurrence of jitter images, and to reduce bearing wear and the load on the drive unit of the copying machine main body.

Also in this structure, as shown in FIG. 8B, before the developing unit 1 is driven, a gap t is formed between the driving side bearing 4a and the supporting side plate 6a of the photosensitive belt 60. Although the positioning of the developing roller 3 may be incomplete due to this, as described above, the main motor 14 is turned on while the gap t is present, and the main body drive gear 1
When the drive gear 16 on the side of the developing unit 1 is driven via 5, a force F for moving the developing unit 1 toward the photoconductor unit 6 is generated as shown in FIGS. 7 and 11. Therefore, even on the drive side where the positioning is incomplete, the outer surface of the drive side bearing 4a contacts the supporting side plate 6a by the force Fcosα generated by the meshing of the teeth of the gears 15 and 16, and the desired positioning is performed. The condition at this time is Fcos α
+ F ₁ > P + T.

Further, in the above embodiment, the length 1 from the center of rotation of the driving cam 9a to the tip of the pressing portion is defined as the driven cam 9a.
The length L is shorter than the length L (conventional length) from the center of rotation to the tip of the pressing portion, but instead of this, the elastic characteristics of the leaf spring 10 may be different between the driving side and the driven side. That is,
The material, shape, and the like of each leaf spring 10 are set so that the restoring force of the leaf spring 10 on the driving side when the same pressing force is applied is smaller than the restoring force of the leaf spring 10 on the driven side.
In this case, the length l of the driving side cam 9a and the driven side cam 9b
The lengths L may be set to the same length. Also, the leaf spring 1
Instead of making the elastic characteristic of 0 different, the characteristic of the spring 13 may be made different between the driving side and the driven side.

Further, in the above embodiment, the photoconductor belt 60 is used as the image carrier, but instead of this, a photoconductor drum or the like may be used. In the above embodiment, the bearings 4a, 4b of the developing roller 3 are pressed against the supporting side plates 6a, 6b of the photosensitive belt 60 to position the developing roller 3, but instead of this, the bearings 4a, 4b are used. May be brought into direct pressure contact with the image bearing member itself, for example, a contact portion of the photoconductor belt with the shaft-rotating member, or the photoconductor drum.

Further, in the above embodiment, the leaf spring 10, the driving side cam 9a, the driven side cam 9b, etc. are used as the urging means for urging the guide rail 5 toward the photoconductor unit 6 side. The present invention is not limited to this, and a spring, a hydraulic device, or various urging means appropriately combining them can be used.

Further, in the above-described embodiment, the developing roller 3 receives the force in the direction from the gear of the driving system toward the photoconductor belt 60 when the developing unit 1 is driven. It can also be applied to the case where 3 receives a force in the direction away from the photoconductor belt 60 from the gear of the drive system. In this case, for example, the pressure contact force of the drive side bearing 4a to the support side plate 6a before the development unit 1 is driven is
Set to be larger than the pressure contact force on the driven side. As a result, both pressure contact forces when the developing unit 1 is driven become substantially the same, and the positioning of the developing roller 3 can be performed more reliably than before.

[0026]

According to the invention of claims 1 to 3, the pressure contact force of the driving side bearing of the developer bearing member to the image bearing member or its supporting side plate when the developing device is driven is the image bearing of the driven bearing. It is almost the same as the pressure contact force to the body or its supporting side plate, and the sliding force between the journal on the drive side of the development carrier drive shaft and the inner surface of the bearing when driving the developing device can be made smaller than before, so that the occurrence of a jitter image With good image quality without
The bearing wear and the load on the drive unit of the image forming apparatus main body can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a developing unit 1 used in a copying machine according to an embodiment.

FIG. 2 is an explanatory view of an inserting operation of the developing unit 1 into the copying machine main body 100.

FIG. 3 is a perspective view showing a positional relationship between the developing unit 1 and a photoconductor unit 6.

FIG. 4 is a perspective view showing a correspondence relationship between bearings 4a and 4b of the developing roller and supporting side plates 6a and 6b of the photosensitive belt.

FIG. 5A is a perspective view showing a detailed configuration of a guide rail 5 and its periphery. (B) is a front view of the guide rail 5.

FIG. 6 is a driving side cam 9a and a driven side cam 9 according to the embodiment.
The perspective view which shows the shape of b.

FIG. 7 is a front view showing a force acting on the developing unit 1 and the guide rail 5 according to the embodiment.

FIG. 8A is an explanatory diagram showing a pressure contact state between a bearing 4b and a support side plate 6b of the photoconductor unit 6 on the developing roller driven side. FIG. 6A is an explanatory view showing a pressure contact state between a bearing 4a and a supporting side plate 6a of the photoconductor unit 6 on the developing roller driving side.

FIG. 9 is a perspective view showing an outline of a drive system of a developing roller 3.

FIG. 10 is a partial perspective view showing a specific configuration of second biasing means according to a modification.

FIG. 11 is a plan view showing forces acting on the developing unit 1 and the guide rail 5 according to the modification.

[Explanation of symbols]

 1 Development Unit 3 Development Roller 4a Drive Side Bearing 4b Driven Side Bearing 5 Guide Rail 6 Photosensitive Unit 6a Drive Side Support Side Plate 6b Driven Side Support Side Plate 9a Drive Side Cam 9b Driven Side Cam 10 Leaf Spring 13 Spring 17 Leaf Spring 60 Photosensitive Body Belt 100 Copier body 102c Cutting and bending section

Claims (3)

[Claims] 1. A developing device, which has a developer carrying member arranged in contact with or in proximity to an image carrying member and is detachable from the main body of the image forming apparatus, and the developing device in the image forming apparatus are required. Urging means for urging the developing device into the image forming apparatus main body according to the above, and after inserting the developing device into the main body of the image forming apparatus, the urging means drives the bearing and the driven side of the developer carrying member. In an image forming apparatus for positioning the developer bearing member by pressing a bearing against the image bearing member or a supporting side plate thereof, the urging means is used for the image bearing member of the driving side bearing when the developing device is driven. Alternatively, the image forming apparatus is configured such that the pressure contact force to the supporting side plate thereof is substantially the same as the pressure contact force of the driven side bearing to the image carrier or the supporting side plate. 2. The image forming apparatus according to claim 1, further comprising a guide member for guiding the developing device while mounting the developing device when the developing device is inserted into the main body of the image forming device. A plate-shaped spring member attached to the guide member on the drive side and the driven side of the rotation shaft of the developer carrying member, and a rotatable drive side cam and driven side for pressing the plate spring member as necessary. A length from the center of rotation of the drive side cam to the tip of the pressing portion,
The image forming apparatus according to claim 1, wherein a length from a rotation center of the driven cam to a tip of the pressing portion is different. 3. The image forming apparatus according to claim 1, further comprising a guide member for guiding the developing device while mounting the developing device when the developing device is inserted into the main body of the image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising drive side biasing means for biasing only a drive side end portion of the guide member corresponding to the drive portion in a direction away from or toward the image carrier. apparatus.