JPH10186851A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict a change in gap between a latent-image carrier and a developer carrier even in case an external force from a drive input part into a developing unit act and to prevent image-quality defect such as density irregularity by composing so as to restrict the swinging motion of the development unit which accompanies the external force acting on the drive input part. SOLUTION: The device is equipped with a latent-image positioning member 3 for positioning and fixing a latent-image unit 1 in relation to a device main body, a development positioning member 4 for positioning and engaging the developing unit 2 in relation to the latent-image unit 1 so that it is free to be swinguable, and a drive input member 5 for transmitting a driving force from a drive source 6 to a member to be driven. The drive input member 5 functions to take in the driving force from the drive source 6 and to transmit it the member to be driven which incorporates the developer carrier 2a. At the time, because the drive input member 5 is provided on a swing shaft that is shared with the development positioning member 4 of the developing unit 2, the developing unit 2 does not swing around the swing shaft even in case an external force acts on the drive input member 5.

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 for visualizing an electrostatic latent image on a latent image carrier, and more particularly, to a latent image unit including at least a latent image carrier, and a latent image unit. The present invention relates to an improvement in an image forming apparatus of a type having at least a developing unit including at least a developer carrier opposed to a carrier.

[0002]

2. Description of the Related Art In general, for example, as an electrophotographic image forming apparatus, an electrophotographic device such as a charger, a developing device and a transfer device is usually provided around a latent image carrier such as a photosensitive drum. Among these various devices, those having the same life are collectively made into a process cartridge, and a device that can easily be replaced when the useful life has expired has already been provided ( For example, see JP-A-2-123375 and JP-A-6-130741).

[0003] As a process cartridge of this type,
For example, as shown in FIG. 9, a latent image carrier 501, a latent image unit 500 including a charging device and a cleaning device (not shown), a developing roll 511 opposed to the latent image carrier 501, and other developing functions A developing unit 510 including components, and positions and fixes the latent image unit 500 in a main body housing (not shown).
0 is pivotally positioned and engaged with a pivot shaft (oscillation shaft) 512, and further, the developing unit 510 is urged in a predetermined direction by an urging spring 520.
A device in which the gap between the developing roller 511 and the developing roll 511 is adjusted by a gap adjusting member (not shown) such as a tracking roll has already been provided. And
An input gear (drive input gear) 513 for taking in a driving force from a driving developing motor (not shown) is provided outside the developing unit 510.
From the developing roller 51 via the transmission gear 514.
1 is transmitted.

[0004]

In this type of process cartridge, the input gear 513 is used.
Since the rotation shaft of the developing unit 510 and the pivot shaft 512 of the developing unit 510 are separated by a predetermined span L, for example, when an external force as shown by an arrow is applied to the input gear 513, the developing unit 510 51
2 and the latent image carrier 501
There is a technical problem that the gap between the developing roller 511 and the developing roller 511 fluctuates, and image defects such as density unevenness easily occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems. Even when an external force acts on a drive input portion into a developing unit, a latent image carrier and a developer An object of the present invention is to provide an image forming apparatus which suppresses a gap variation with a carrier and prevents image quality defects such as density unevenness.

[0006]

That is, according to the present invention, as shown in FIG. 1, a latent image carrier 1 for forming and carrying an electrostatic latent image is provided.
a latent image unit 1 including at least a developing unit 2 and a developing unit 2 including at least a developer carrier 2a opposed to the latent image carrier 1a. A positioning member 3 for positioning and fixing the developing unit; a developing positioning member 4 for positioning and engaging the developing unit 2 so as to be able to swing with respect to the latent image unit 1; And a drive input member 5 which receives a driving force from a driving source 6 and transmits the driving force to a driven member including a developer carrier 2 a in the developing unit 2.

In such technical means, the subject of the present application is not limited to one embodiment in which the latent image unit 1 and the developing unit 2 are provided, but can be naturally applied to an embodiment in which a plurality of units are provided for forming a color image. It is. As the latent image carrier 1a of the latent image unit 1, a photoconductor, a dielectric, or the like may be appropriately selected as long as an electrostatic latent image is carried and formed, and the form may be a drum shape or a belt shape. . The devices incorporated in the latent image unit 1 include:
A charging device, a cleaning device, a pre-transfer processing device, a pre-cleaning device, a pre-charging device, and the like may be appropriately combined as needed.

Further, as long as the developing unit 2 includes at least the developer carrier 2a, the developing unit is not limited to the type of the developer, the contact development, and the non-contact development. Absent. And the developing unit 2
Various devices required for development may be appropriately incorporated in addition to the developer carrier 2a, or a device irrelevant to development may be incorporated due to the necessity of layout. .

Further, the developing unit 2 is swingably positioned and engaged with the latent image unit 1 by the developing positioning member 4. Such a swing structure is employed as a support structure of the developing unit 2. Is a device for urging the developing unit 2 in a predetermined direction by an urging member such as a spring, and a gap adjusting member (provided coaxially with the developer carrier) between the latent image carrier 1a and the developer carrier 2a. By interposing a tracking roll or a tracking sheet sandwiched between the latent image carrier 1a and the developer carrier 2a) to maintain a constant gap between the two.

The drive input member 5 is a functional member for taking in the driving force from the drive source 6, and usually a drive is provided between the drive input member 5 and the developer carrier 2a and other driven members. A transmission member is interposed.

Next, the operation of the above technical means will be described. In FIG. 1, a drive input member 5 includes a drive source 6
And acts to transmit the taken-in driving force to the driven member including the developer carrier 2a. At this time, since the drive input member 5 is provided coaxially with the swing axis of the developing positioning member 4 of the developing unit 2,
Even if an external force acts on the drive input member 5, the developing unit 2 does not swing about the swing axis.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the accompanying drawings. FIG. 2 shows an embodiment of a color image forming apparatus to which the present invention is applied. In the figure, the color image forming apparatus vertically arranges image forming units 22 (specifically, 22a to 22d) of four colors (yellow, magenta, cyan, and black) in a main body housing 21 in a vertical direction. A paper feed cassette 23 for accommodating supply paper is disposed below the paper feed cassette 23, and a paper feed path serving as a paper feed path from the paper feed cassette 23 is provided at a location corresponding to each image forming unit 22. The road 24 is arranged vertically.

In this embodiment, the image forming units 22 (22a to 22d) form toner images for yellow, magenta, cyan, and black in order from the upstream side of the paper transport path 24. A process cartridge 30 for forming toner images of respective colors on the photosensitive drum 33 by, for example, electrophotography; and a laser for irradiating the photosensitive drum 33 with laser light to write an electrostatic latent image on the photosensitive drum 33 The image forming apparatus includes an exposing device 40 and a transfer roll 50 that is disposed to face the photoconductor drum 33 and transfers the toner images of the respective colors formed on the photoconductor drum 33 to a sheet (not shown).

Further, in the present embodiment, the paper feed cassette 2
3 is provided with a feed roll 61 for sending out the paper at a predetermined timing. The paper transport path 24 located between the feed roll 61 and the transfer portion of the most upstream image forming unit 22a has a nip on the entrance side. A transport roll 62 is provided, and an optical paper passage sensor 63 is provided downstream of the transport roll 62. In the present embodiment, the paper passage sensor 63 detects the leading edge of the paper, and for example, based on the detection timing, for example, each image forming unit 2
The writing timing of the electrostatic latent image of the second laser exposure device 40 is controlled.

Further, the most downstream image forming unit 22d
A fixing device 64 is provided in the sheet conveying path 24 located downstream of the fixing device 64.
Function as a nip transport roll 65 on the exit side. A discharge roll 66 for discharging the paper is provided downstream of the fixing device 64, and the discharged paper is stored in a storage tray 67 formed above the main body housing 21.

Next, the process cartridge 30 used in this embodiment will be described in detail with reference to FIGS. FIG. 3 shows the main body housing 21 of the process cartridge.
It is an exploded perspective view showing the outline of the support structure inside. In the figure, a process cartridge 30 includes a photosensitive drum 3
The latent image unit 31 includes a latent image unit 31 and a developing unit 32 that is swingably positioned and engaged with the latent image unit 31.

First, the latent image unit 31 will be described. As shown in FIGS. 4 to 6, the latent image unit 31 rotatably supports the photosensitive drum 33 on bearings on both side walls of the latent image housing 34, and also includes the photosensitive drum 33.
Are provided on both sides of the latent image housing 34, and a charging roll 35 for charging the photosensitive drum 33 in advance is provided in the latent image housing 34.
A cleaner 36 (for example, a cleaner housing 361 extending in the lateral direction) from which residual toner on the photosensitive drum 33 is removed.
(A mode in which a blade 362 for scraping residual toner is disposed at a position facing the photosensitive drum 33). Reference numeral 37 denotes a pressing spring that presses the charging roll 35 toward the photosensitive drum 33 with a predetermined pressure. Further, the width direction of the end of the latent image housing 34 opposite to the position of the photosensitive drum 33 (corresponding to the axial direction of the photosensitive drum 33)
A pair of substantially U-shaped positioning engagement grooves 101 are formed on both sides, and a positioning engagement hole 102 is formed through and penetrates substantially the center of both sides of the latent image housing 34 in the width direction below.

A support structure for the latent image unit 31 is provided on the apparatus main body side. In the present embodiment, the main body housing 21 includes a cartridge housing housing 211 for housing the process cartridge 30 and a transfer roll 50.
And a main body cover 212 that is rotatably supported and closes the opening of the cartridge housing housing 211 in an openable and closable manner. Latent image unit 31 in the present embodiment
Of the photosensitive drum 3 on the body cover 212 side.
3 are rotatably provided with positioning rolls 111 and 112 on which both end supporting portions 33a are contact-supported at a plurality of locations, while engaging with positioning engagement grooves 101 of the latent image unit 31 on both inner walls of the cartridge housing housing 211. In addition to the positioning pin 113 provided, a pressing roll 114 is provided for pressing both end supporting portions 33 a of the photosensitive drum 33 toward the positioning rolls 111 and 112.

In particular, in this embodiment, one positioning roll 111 is provided coaxially with the transfer roll 50 at both ends of the transfer roll 50. Further, support brackets 115 are provided on both inner walls of the cartridge housing housing 211.
A rotary arm 116 is rotatably supported on the support bracket 115 with an intermediate portion thereof being pivotally mounted. A pressing roll 114 is rotatably supported at the tip of the rotary arm 116, and the rotation arm 116 is A biasing spring 117 for pressing is provided between the other end and the support bracket 115, and the positioning pin 113 is projected from the support bracket 115.

Next, the developing unit 32 will be described. In the present embodiment, as shown in FIGS. 4, 5, and 7, the developing unit 32 is disposed below the latent image unit 31 and extends in the lateral direction.
The developing housing 121 contains a developer 127 (one-component developer composed of a non-magnetic developer or a magnetic developer) containing a toner of a predetermined color. Agitators 122 and 123 as a developer stirring member are disposed, and a developing roll 124 is disposed at an opening portion of the developing housing 121 facing the photosensitive drum 33.
A developer supply roll 125 for supplying the developer in the development housing 121 to the development roll 124 is disposed in the vicinity of the developer roll 121. Further, the layer thickness of the developer on the development roll 124 is regulated, A developer charging blade 126 is provided. A developing bias (not shown) is applied to the developing roll 124, and the developing roll 124
The upper developer (toner) flies to the photosensitive drum 33 side.

A positioning engagement hole 131 is formed in a substantially central portion of the developing unit 32 near the upper side of both widthwise side walls of the developing housing 121 so as to penetrate therethrough.
A positioning set pin (pivot shaft) is provided in the positioning engagement hole 131 of the image forming apparatus and the positioning engagement hole 102 of the latent image unit 31.
The developing unit 32 is swingably supported by the latent image unit 31.

Further, a drive transmission system 140 composed of, for example, a gear train is provided on the outer wall on one side in the width direction of the developing housing 121 of the developing unit 32. In this embodiment, the drive transmission system 140 is provided with an input gear 141 coaxially with the pivot shaft 132, as shown in FIGS. 5 and 7B, while the agitators 122 and 123 and the developing roll 1 are provided.
24, an agitator gear 142, 143, a development roll gear 144, and a developer supply roll gear 145 are provided coaxially with the developer supply roll 125, respectively.
1 through the agitator gear 142, the idler gear 146, and the agitator gear 123.
2 and 123, and idler gear 147,
Development Roll Gear 144 and Developer Supply Roll Gear 145
, The developing roll 124 and the developer supply roll 125 are driven to rotate. Reference numeral 148 denotes a blind cover for blinding the drive transmission system 140 from outside.

Further, in the present embodiment, as shown in FIG. 3, one drive motor 151 and a drive meshing with the input gear 141 of each process cartridge 30 are provided on the outer wall on one side in the width direction of the cartridge housing housing 211. A drive composed of a transmission gear 152, a drive gear 153 coaxially connected to each drive transmission gear 152, and one connected to the shaft of the drive motor 151, and an idler gear 154 interposed between and meshed with each drive gear 153. Distribution system 15
0 is provided.

Next, the assembly of the process cartridge 30 according to the present embodiment and the incorporation into the apparatus main body will be described. First, when assembling the process cartridge 30, as shown in FIGS. 5 and 8A, the developing unit 32 is disposed below the latent image unit 31, and the positioning engagement hole 102 of the latent image housing 34 is provided. After aligning the positioning engagement holes 131 of the developing housing 121 with each other, a positioning set pin (pivot shaft) 132 is passed through the positioning engagement holes 102 and 131 to integrate them. Further, in this embodiment, as shown in FIG. 8A, for example, a tracking sheet 160 for adjusting the gap between the non-image forming area of the photosensitive drum 33 and the developing roll 124 is interposed between the non-image forming area and the developing roll 124. Between the latent image unit 31 and the developing unit 32
The developing roller 124 may be pressed against the photosensitive drum 33 by the urging force of the urging spring 161 to hold the tracking sheet 160 therebetween. Note that, in FIG. 8A, the drive transmission system 140 is omitted.

Next, when the thus assembled process cartridge 30 is to be incorporated into the apparatus main body, the positioning pins 11 on the cartridge housing housing 211 side are used.
3 is engaged with the positioning engagement groove 101 of the latent image unit 31, and both end supporting portions 33 a of the photosensitive drum 33 are supported by the positioning rolls 111 and 112 on the main body cover 212 side, and the cartridge housing housing 211 side is supported. Both ends of the photosensitive drum 33 are supported by the pressing roll 114.
a may be pressed toward the positioning rolls 111 and 112.

When the process cartridges 30 are incorporated in the apparatus main body in this manner, the input gear 141 of each process cartridge 30 meshes with the drive transmission gear 152 of the drive distribution system 150. Therefore, the drive motor 1
The driving force from 51 is taken into the input gear 141 of the developing unit 32 of each process cartridge 30 via the drive distribution system 150, and the agitators 122, 123, the developing roll 124, and the like of each developing unit 32 via the drive transmission system 140. It is transmitted to the developer supply roll 125.

At this time, when an external force as shown by an arrow is applied to the input gear 141, for example, as shown in FIG.
1, the external force is applied to the engaging holes 102, 13 of the positioning set pin (pivot shaft) 132.
It is received at one edge. In this state, since a rotational moment about the pivot shaft 132 does not act on the developing unit 32, the developing roller 124 does not separate from the photosensitive drum 33.
No image quality defects such as density unevenness due to the fluctuation of the gap between the photosensitive drum 4 and the photosensitive drum 33 occur. In FIG. 8B, the input gear 141 of the drive transmission system 140,
Gear trains other than the idler gear 147 and the developing roll gear 144 are omitted.

Further, in the present embodiment, even if the photosensitive drum 33 has a variation in outer diameter, an eccentricity error, and a play in a bearing portion, positioning for supporting the outer diameter of the photosensitive drum 33 at two points. By the action of the rolls 111 and 112, the peripheral surface position of the photosensitive drum 33 facing the transfer roll 50 is always constant, and the surface speed of the photosensitive drum 33 passing through the transfer point is kept constant, and the transfer point The span between them is also kept constant. For this reason, in the transfer step, when the image is transferred from the photosensitive drum 33 to the paper, the fluctuation of the image magnification in the process direction is reduced, and the deterioration of the color image quality due to the deviation of the color registration is reduced.

[0029]

As described above, according to the present invention, the structure of the drive input section from the drive source is devised in the type in which the developing unit is swingably positioned and engaged with the latent image unit. , The swinging motion of the developing unit due to the external force acting on the drive input unit is suppressed. Therefore, even when an external force acts on the drive input unit into the developing unit, the latent image carrier and the developer Variations in the gap with the carrier can be suppressed, and thus image quality defects such as density unevenness can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an outline of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating an embodiment of an image forming apparatus to which the present invention has been applied.

FIG. 3 is an exploded perspective view of a main part of the image forming apparatus of FIG. 2;

FIG. 4 is an overall perspective view of a process cartridge used in the embodiment.

FIG. 5 is an exploded perspective view of FIG.

FIG. 6 is an explanatory diagram showing an outline of a latent image unit of a process cartridge.

7A is an explanatory diagram illustrating an outline of a developing unit of a process cartridge, and FIG. 7B is an explanatory diagram illustrating an outline of a drive transmission system of the developing unit.

FIG. 8A is an explanatory diagram showing an attached state of the process cartridge according to the embodiment, and FIG. 8B is an explanatory diagram showing a state when an external force acts on an input gear.

FIG. 9 is an explanatory diagram illustrating an example of a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Latent image unit, 1a ... Latent image carrier, 2 ... Developing unit, 2a ... Developer carrier, 3 ... Latent image positioning member, 4 ...
Development positioning member, 5: drive input member, 6: drive source

Claims (1)

[Claims] A latent image carrier (1) for forming and carrying an electrostatic latent image.
a) a latent image unit (1) containing at least a) and a developer carrier (2a) disposed to face the latent image carrier (1a)
And a developing unit (2) including at least a latent image positioning member (3) for positioning and fixing the latent image unit (1) with respect to the apparatus main body; and a latent image unit (1). A developing positioning member (4) for oscillatingly positioning and engaging the developing unit (2); and a driving force from a driving source (6) provided coaxially with a swing axis of the developing positioning member (4). And a drive input member (5) that is transmitted to a member to be driven including a developer carrier (2a) in the developing unit (2).