JP2856951B2 - Image forming device - Google Patents

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 or a printer employing a transfer system.

[0002]

2. Description of the Related Art FIG. 7 shows a schematic configuration of a conventional image forming apparatus. In FIG. 7, reference numeral 1 denotes a photosensitive drum as an image carrier, which is driven to rotate at a predetermined peripheral speed (process speed) in a direction indicated by an arrow in the figure.

In the course of rotation, the peripheral surface of the photosensitive drum 1 is uniformly and primarily charged to a predetermined polarity by the charger 2. Image exposure L corresponding to image information is performed on the charged surface by image exposure means such as exposure means, and an electrostatic latent image corresponding to the exposure pattern is formed. The electrostatic latent image is developed as a toner image Ta by the developing device 4, and the toner image Ta is transferred to a transfer nip n between the photosensitive drum 1 and a transfer roller 5 which is a transfer rotating member pressed against the photosensitive drum 1. Is sequentially transferred as a transfer toner image Tb to a transfer material P fed at a predetermined timing from a sheet feeding means (not shown). In FIG. 7, reference numerals 6 and 7 denote an inlet-side guide plate and an outlet-side guide plate which are guide members for guiding the transfer material P to the transfer nip portion n, which are fixed to the apparatus main body. ing.

The transfer material P that has passed through the transfer nip n is separated from the surface of the photosensitive drum 1 and conveyed to a fixing unit (not shown), where the transfer toner image Tb is fixed.
It is output as an image formed product (print / copy).
After the transfer, the surface of the photosensitive dome 1 is cleaned by the cleaning device 8 to remove residual contaminants such as transfer residual toner.
It is repeatedly provided for image formation.

Incidentally, the transfer roller 5 has a cored bar 5a.
And a conductive elastic layer 5b of conductive rubber or the like formed into a roller shape by molding or the like on the core 5a.
The both ends of a are rotatably supported by support members (not shown). The transfer roller 5 is disposed substantially parallel to the photosensitive drum 1, is pressed against the surface of the photosensitive dome 1 with a predetermined pressing force, and rotates at substantially the same peripheral speed as the photosensitive drum 1. Then, the power supply 9 transfers the photosensitive drum 1 to the transfer roller 5.
When a bias voltage having a polarity opposite to that of the toner image Ta is applied, the transfer member P introduced into the transfer nip n is electrostatically charged, and the toner image Ta on the photosensitive drum 1 is moved to the transfer member P side. Is transferred as a transfer toner image Tb.

[0006] As described above, the transfer roller 5
The surface layer is composed of a conductive elastic layer 5b. The conductive elastic layer 5b is compressed at the transfer nip portion n, and is decompressed when passing through the transfer nip portion n. Since the release is repeatedly performed, the life of the apparatus is significantly reduced due to fatigue, and the apparatus body is generally replaced several times before reaching the end of its life.

For this reason, the transfer roller 5 is incorporated in the apparatus main body so as to be detachable and replaceable. For maintenance such as replacement work of the transfer roller 5 or removal of the transfer material jammed in the transfer material transport path in the apparatus main body,
The image forming apparatus main body is configured to be largely openable, and process devices such as a photosensitive drum 1, a charging device 2, a developing device 4, and a cleaning device 8 are integrally configured as a process cartridge. It is done to be attached and detached.

Here, the support structure of the transfer roller 5 will be described with reference to FIG.

FIG. 8 is a cross-sectional view of the transfer unit. As shown, a pair of transfer roller bases 10 are mounted on the apparatus main body side. The bearing 1 is slidably fitted in
A spring 12 is compressed between the transfer roller 1 and the transfer roller base 10.

The transfer roller 5 is rotatably supported by the bearing 11 at both ends of the metal core 5 a, so that the transfer roller 5 is rotatably supported by the apparatus main body, and the photosensitive drum is supported by a spring 12. 1 to form a transfer nip n between itself and the photosensitive drum 1.

The transfer roller base 10 is provided with stopper claws 10b and 10c at the openings thereof. For example, since the process cartridge containing the photosensitive drum 1 is detached from the apparatus main body, the photosensitive drum 1 is moved to the apparatus main body. Even when the transfer roller 5 does not exist, the protrusion of the bearing 11 and the transfer roller 5 from the transfer roller
b, 10c. However, the stopper claw 10c
Is configured to rotate and open when subjected to a certain force or more, so that the transfer roller 5 can be taken out in the direction indicated by the arrow X in FIG.

[0012]

On the other hand, the transfer material inlet guide 6 is disposed near the transfer nip portion n between the photosensitive drum 1 and the transfer roller 5 to securely transfer the transfer material P to the transfer nip portion n. Plays the role of guiding the transfer nip n
When the transfer material P is far from the transfer roller 5, the transfer material P is guided to the transfer nip n while being in contact with the transfer roller 5, so that there is a problem that toner scatters during transfer.

Further, since the transfer material inlet guide 6 cannot be arranged within the range where the transfer roller 5 is taken out, if the transfer inlet guide 6 is arranged at the position indicated by the dashed line in FIG. 8, the transfer material P hits the photosensitive drum 1. However, since it is guided to the transfer nip n from the outside, it is sharply bent downward, so that there arises a problem that the printing accuracy is deteriorated and a jam is easily generated.

Therefore, as shown in FIG.
When the transfer material entrance guide 6 is fixed to a guide table 14 positioned by a shaft 13 fixed to the apparatus body and the transfer roller 5 is replaced, the transfer table entrance guide 6 is also removed. Even when the transfer roller 5 is moved closer to the transfer nip portion n, the problem of interference between the transfer roller 5 and the transfer material entrance guide 6 when removing the transfer roller 5 does not occur.

However, according to the above configuration, since one end of the guide table 14 is supported by the transfer roller 5, the guide table 14 swings about the shaft 13 following a change in the position of the transfer roller 5, and In addition, the position of the guide table 14 with respect to the photosensitive drum 1 fluctuates, causing a reduction in printing accuracy and scattering of toner, resulting in a problem that image quality is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to arrange a guide member of a transfer material at an optimum position and to maintain a high positional accuracy of the guide member with respect to an image carrier. It is another object of the present invention to provide an image forming apparatus capable of improving image quality.

[0017]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an image carrier and an image transfer device for transferring an image formed on the image carrier to a transfer material at a transfer position. In an image forming apparatus having a guide member for guiding a material, a positioning member for positioning the image carrier, and a guide holding member for holding the guide member, the guide member is detachably provided on the guide holding member. And
The guide holding member is attached to the positioning member, and a positioning surface of the guide holding member with the guide member is a mounting surface of the guide holding member to the positioning member.

[0018]

According to the present invention, the guide holding member for holding the guide member is attached to the positioning member for positioning the image carrier, and the guide member is detachably provided on the guide holding member. Since the positioning surface of the guide holding member is used as a mounting surface for the positioning member, the guide member can be freely arranged at an optimum position, and the positional accuracy of the guide member with respect to the image carrier is increased, and the printing accuracy is reduced. Image quality can be improved by preventing scattering of the developer and the developer.

[0019]

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

FIG. 3 is a longitudinal sectional view of an image forming apparatus according to the present invention.
The transfer material P stored in the inside is fed by a feed roller 52, and subsequently, a first feed roller pair 53 and a second feed roller pair 54 use the upper feed guide 55 and the lower feed guide 5.
6 is conveyed. Next, when the leading end of the transfer material P passes through the nip portion between the registration upper roller 57 and the registration lower roller 58 and the sensor (not shown) is turned off by the sensor lever 59, the driving of the paper feeding motor (not shown) is started. The transfer material P is stopped and maintains a standby state.

On the other hand, after a synchronization signal is sent from the host computer, writing of an image on the photosensitive drum 60, which is an image carrier, is started by the laser light L after a predetermined time, and at the same time, the paper feed motor is driven to transfer the image. The material P passes between the lower transfer guide 61 and the upper transfer guide 62, which are guide members, and is sent out to the transfer nip portion n of the photosensitive drum 60 and a transfer roller 63 which is a rotating body for transfer. Is a toner image is transferred. Thereafter, the transfer material P is transferred to the fixing device 6.
4, the toner image is fixed there, discharged by the discharge roller pair 65 outside the apparatus, and stacked on a discharge tray 66.

Here, the configuration of the transfer section of the image forming apparatus will be described in detail with reference to FIGS. FIG. 1 is a longitudinal sectional view of the transfer unit, and FIG. 2 is a partial plan view of the transfer unit.

As shown in the figure, a pair of transfer roller bases 67 are mounted on the apparatus main body side.
7, a bearing 68 is slidably fitted in the center direction of the photosensitive drum 60, and a spring 69 is compressed between the bearing 68 and the transfer roller base 67.

The transfer roller 63 has its core 63
a is rotatably supported by the bearings 68 so that it is rotatably supported by the apparatus main body and is pressed against the surface of the photosensitive drum 60 by a spring 69 to transfer the photosensitive drum 60 to the photosensitive drum 60. A nip n is formed. At least one of the pair of bearings 68 is made of a conductive material, and the transfer bias voltage is applied to the transfer roller 63 via a spring 69 and a bearing 68 made of a conductive material.

The transfer roller base 67 is provided with stopper claws 67b and 67c at the opening thereof. For example, since the process cartridge containing the photosensitive drum 60 has been removed from the apparatus main body, the photosensitive drum 60 is moved to the apparatus main body. Even when the transfer roller 63 does not exist, the protrusions of the bearing 68 and the transfer roller 63 from the transfer roller base 67 are prevented by the stopper claws 67b and 67c. However, the stopper claw 67 </ b> C is configured to rotate and open when it receives a certain force or more, and the transfer roller 63 can be attached to and detached from the transfer roller base 67.

On the other hand, the photosensitive drum 60 is positioned by being fitted into a concave portion 70a of a drum support 70 as a positioning member thereof.

The lower transfer guide 61 and the upper transfer guide 62 are fitted and fixed to a guide knob 71, respectively.
The guide knob 71 is moved by an arrow A in FIG.
Biased in the direction. Projection 61a of transfer lower guide 61
Is incorporated in a hole formed in a guide base 73 which is a guide holding member fixed to the surface 70b of the drum support base 70, and is urged by the guide spring 72 to be pressed against the surface 73a of the guide base 73. Thus, the lower transfer guide 61 and the upper transfer guide 62 are positioned.

The surface 73a of the guide table 73 is attached to the surface 70b of the drum support 70, and this surface 70b is provided in the recess 7 where the photosensitive drum 60 is positioned.
Since the positional accuracy of the lower end portion 61a of the lower transfer guide 61 with respect to the photosensitive drum 60 is maintained high, the positional accuracy of the lower end portion 61a of the lower transfer guide 61 is maintained high.

In this embodiment, the guide table 73, the lower transfer guide 61, and the upper transfer guide 62 are both made of sheet metal, and the guide table 73 is grounded to ground via a resistor (not shown). The lower transfer guide 61 and the upper transfer guide 62 that are in contact with the guide table 73 are also grounded to the ground via a resistor. The grounding to the ground in this way is to prevent the device carried by the transfer material P and accumulated in the guide table 73, the lower transfer guide 61, etc. from causing a discharge phenomenon and causing the apparatus to malfunction.
Further, the reason why the resistance is interposed between the ground and the ground is to prevent the charge from flowing abruptly to the transfer lower guide 61 from the transfer roller 63 to the transfer lower guide 61 and causing transfer failure.

Further, in order to prevent unevenness in the charge of the transfer material P charged by friction between the paper feed roller 52, the first transport roller pair 53, the second transport roller pair 54, and the registration roller pairs 57 and 58 shown in FIG. The static elimination brush 74 shown in FIG. 1 is guided to the ground through the brush holder 75 and the guide stand 73.

Further, an insulating sheet 76 such as Mylar is attached to the tip 61a of the lower transfer guide 61.
This prevents the bias voltage of the transfer roller 63 from leaking to the lower transfer guide 61.

When the photosensitive drum 60 is removed from the apparatus main body and the transfer roller 63 is replaced, the guide knob 71 is pulled in the direction of arrow B in FIG.
1 is disengaged from the guide spring 72, so that the transfer lower guide 6
1. Transfer upper guide 62, insulating sheet 76, neutralizing brush 7
4 and the brush holder 75 are integrally removed from the guide table 73. Therefore, since there is no obstacle above the transfer roller 63, the transfer roller 63 can be easily replaced. After the transfer roller 63 is replaced, if the guide knob 71 is again held and engaged with the guide spring 72, the lower transfer guide 61, the upper transfer guide 62 and the like are fixed again to the guide table 73 as a single unit.

As described above, in this embodiment, the guide base 73 is fixed to the drum support 70 for positioning the photosensitive drum 60, and the transfer lower guide 61 and the like are detachably attached to the guide base 73. As a result, the transfer lower guide 61 can be freely arranged at an optimum position, and the positional accuracy of the transfer lower guide 61 with respect to the photosensitive drum 60 is improved, thereby preventing a decrease in printing accuracy and toner scattering, thereby improving image quality. Can be achieved.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a longitudinal sectional view of a transfer portion of the image forming apparatus according to the second embodiment. In this figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In this embodiment, the drum support 70 also serves as the guide table 73 (see FIG. 1) in the first embodiment, and the other configuration is the same as that of the first embodiment.
Accordingly, the projection 61a of the lower transfer guide 61 is urged by the guide spring 72 and pressed against the surface 70b of the drum support 70, whereby the lower transfer guide 61 is positioned. The transfer lower guide 61 is grounded to ground via a resistor (not shown).

According to the second embodiment, the first
In addition to obtaining the same effects as those of the embodiment, it is possible to obtain the effects that the accuracy of parts can be increased, the number of parts can be reduced, the cost can be reduced, and the like.

FIGS. 5 and 6 show a third embodiment of the present invention. FIGS. 5 and 6 are longitudinal sectional views of the transfer section of the image forming apparatus according to the third embodiment. In these figures, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In this embodiment, a lever member 77 is provided which engages with a shaft 61b provided on the transfer lower guide 61 and a transfer roller shaft 63a, and the other structure is the same as that of the first embodiment. is there.

In this embodiment, the lower transfer guide 61 and the upper transfer guide 62 are held by the guide table 7 while holding the guide knob 71.
3, the lever member 77 is removed as shown in FIG.
And the transfer roller 63 is also removed. Then, when the lever member 77 is moved in the axial direction, the shaft 6
1b and 63a, the transfer roller 63 can be taken out alone.

According to the third embodiment, the first
The same effect as that of the embodiment can be obtained, and the stained transfer roller 6
Thus, the transfer roller 63 can be removed without touching the surface of the transfer roller 3.

[0041]

As is apparent from the above description, according to the present invention, the image carrier and the image formed on the image carrier are transferred to the transfer material in order to transfer the image formed on the image carrier to the transfer material at the transfer position. In an image forming apparatus having a guide member for guiding a material, a positioning member for positioning the image carrier, and a guide holding member for holding the guide member, the guide member is detachably provided on the guide holding member. The guide holding member is attached to the positioning member, and the positioning surface of the guide holding member with the guide member is an attachment surface of the guide holding member to the positioning member. At the optimum position, the positional accuracy of the guide member with respect to the image carrier can be kept high, and the image quality can be improved. It is.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a transfer unit of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial plan view of a transfer unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of the image forming apparatus according to the present invention.

FIG. 4 is a longitudinal sectional view of a transfer unit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a transfer unit of an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a transfer unit of an image forming apparatus according to a third embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a main part of an image forming apparatus employing a transfer method.

FIG. 8 is a longitudinal sectional view of a transfer unit of an image forming apparatus according to a conventional example.

FIG. 9 is a longitudinal sectional view of a transfer section of an image forming apparatus according to a conventional example.

[Description of Signs] 60 Image carrier 61 Transfer lower guide (guide member) 61b Shaft fixed to guide member 63 Transfer roller (transfer rotating body) 63a Transfer roller shaft (transfer rotating body) 70 Drum support (Image carrier positioning member) 73 Guide base (guide holding member) 77 Lever member P Transfer material

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Goto 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (56) References JP-A-2-72382 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) G03G 15/16

Claims (3)

(57) [Claims] An image bearing member formed on the image bearing member;
To the transfer position to transfer the image to the transfer material at the transfer position
A guide member for guiding the transfer material and positioning of the image carrier;
Positioning member to be fixed, and a guide for holding the guide member.
And a guide holding member , wherein the guide member is detachably provided on the guide holding member.
The guide holding member is attached to the positioning member.
And the position of the guide holding member with respect to the guide member.
The determining surface is the guide holding member to the positioning member.
An image forming apparatus comprising: a mounting surface . 2. The apparatus according to claim 1 , wherein said apparatus is formed on said image carrier.
A transfer rotator for transferring an image to a transfer material at the transfer position;
The transfer material passes between the image bearing member and the transfer rotating member.
The image forming apparatus according to claim 1, wherein a nip portion to be passed is formed . 3. The apparatus according to claim 1, wherein the apparatus comprises:
It has a lever member that engages with the shaft fixed to the guide member.
And detachably provided with this <br/> the image forming apparatus according to claim 1, wherein the lever member with respect to both axes.