JP2982027B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus,
In particular, when the transfer material is electrostatically adsorbed by the transfer belt to transfer the image on the photosensitive member to the transfer material and transported, the transfer material is preferably wrapped around the photosensitive member at the transfer portion and prevented from being a transport obstacle. And an electrophotographic apparatus comprising the same.

[0002]

2. Description of the Related Art A conventional electrophotographic apparatus is disclosed in
As described in JP-A-95668, in a registration roller section for feeding a transfer material to a photoreceptor, the transfer roller is conveyed with a certain nip width sandwiching the leading end of the transfer material between an elastic roller and a metal roller, and is directed downward to the photoreceptor. The curl was surely applied, and the transfer material was easily separated from the photoreceptor.

[0003]

The curl given to the leading end of the transfer material in the prior art described above is, in the case of a transfer apparatus using a transfer belt, because the transfer material is sandwiched between the transfer belt and the photosensitive member. However, it is almost completely lost. Further, the so-called sag at the leading end of the transfer material remains as it is, and a gap is formed between the leading end of the transfer material and the transfer belt. As a result, discharge occurs due to the transfer corona, and the transfer material remains wound around the photoconductor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic device having a means for preventing discharge due to a transfer corona generated in a minute gap between a tip of a transfer material and a transfer belt and preventing winding of the transfer material around a photosensitive member. A photographic device is provided.

[0005]

According to the present invention, in order to achieve the above object, a transfer material is electrostatically attracted to a surface of an insulating transfer belt, conveyed, and a toner image held on a photoreceptor surface is transferred to the transfer material. The present invention proposes an electrophotographic apparatus which includes means for releasing contact between a transfer belt and a photosensitive member when a leading end of a transfer material reaches a transfer section.

[0006] The means for releasing the transfer belt and the photoreceptor is, specifically, a movable roller provided on the inner peripheral surface side or outer peripheral surface side of the transfer belt near the transfer section, and means for driving this roller. It consists of.

In the case where a roller is provided on the outer peripheral surface side, it is desirable to form a small diameter portion of the roller over the width of the transfer member in order to avoid contact between the roller and the transfer member.

In any of the above electrophotographic apparatuses, a roller for tensioning the transfer belt at a position opposite to the movable roller with respect to the transfer portion can be provided.

According to another aspect of the present invention, there is provided an electronic apparatus comprising: means for releasing a transfer belt and a photoreceptor; a roller for suspending the transfer belt itself; and means for driving the roller. A photographic device is proposed.

In any of the above cases, the roller driving means is, for example, an eccentric cam.

[0011]

Before describing the operation of the present invention, the phenomenon of winding of a transfer material around a photosensitive member in the prior art will be described in more detail.

FIG. 9 is a perspective view showing the internal structure of a general electrophotographic apparatus. The transfer material, for example, the recording paper 4 conveyed from the hopper 13 is conveyed onto the transfer belt 2 by being sandwiched by the registration rollers 8. The transfer material 4 is further conveyed while being electrostatically attracted to the transfer belt 2. Transfer material 4
The transfer unit receives a transfer corona from a transfer unit 3 disposed on the back surface of the transfer belt 2 at the transfer unit, and transfers the developed image held on the photoconductor 1. When the transfer process is completed, the transfer material 4 is conveyed while being electrostatically attracted to the transfer belt 2, the transfer image is fixed by the fixing roller 6, and is discharged to the outside by the discharge roller 10. In FIG. 9, 5 is a conveyance guide for the transfer material 4, 7 is a tray for supplying the transfer material from the front of the electrophotographic apparatus, 9 is a cleaner for the photoconductor 1, and 11 is an electronic latent image on the photoconductor 1. It is a developing device.

FIG. 10 is a side view showing the state of the leading end of the transfer material 4 near the transfer section in the electrophotographic apparatus shown in FIG.

The transfer material 4 is transferred to the transfer unit 3 at the transfer unit 3b.
The transfer corona 3 a receives the transfer corona 3 a and is charged and electrostatically attracted to the transfer belt 2. If toner is present on the photoconductor 1, a gap is formed between the photoconductor 1 and the transfer material 4 through the toner.
Side is weakly attracted, remains adsorbed on the transfer belt 2, and is conveyed normally.

[0015] However, as shown in FIG.
When the gap 4b is formed between the transfer belt 2 and the transfer belt 2, the gap 4b
Then, the charge on the transfer belt 2 is discharged, and the transfer material 4 is charged to the opposite polarity to the transfer belt 2. When the transfer corona 3a becomes positively charged and the photoconductor 1 is negatively charged, when a gap discharge occurs, the transfer material 4 is positively charged. In particular, when there is no toner on the photoreceptor 1, the positively charged transfer material 4
Is attracted to the negatively charged photoconductor 1.

Further, the end face of the transfer material 4 may be deformed such as a sag 4a during cutting in the manufacturing process of the transfer material 4. The side of the sagging 4a is the transfer belt 2
When the transfer material 4 is sandwiched between the photosensitive member 1 and the transfer belt 2 at the transfer portion, a gap 4b is formed between the transfer belt 2 and the transfer material 4 by the sag 4a, and Furthermore, it becomes easy to be adsorbed.

FIG. 11 is a side view for explaining the winding of the transfer material 4 around the photosensitive member 1. In the transfer section, the transfer material 4
Once the leading end of the transfer material 4 is once attracted to the photoreceptor 1, the leading end of the transfer material 4 is separated from the transfer belt 2, so that a gap 4c is created between the transfer belt 2 and the transfer material 4, and the gap discharge further proceeds. Then, the transfer material 4 is further attracted to the photoconductor 1.

FIG. 12 is a diagram showing an example of the electrostatic attraction force of the transfer material 4 to the transfer belt 2 at each position. The attraction force of the transfer material 4 to the transfer belt 2 becomes smaller toward the end face, and particularly the end face becomes almost zero. Therefore, the transfer material 4
Once the end surface of the photoconductor 1 is adsorbed to the photoconductor 1, the adsorption to the photoconductor 1 continues, and the end surface is wound around the photoconductor 1.

In order to prevent the winding around the photosensitive member 1, when the leading end of the transfer material 4 reaches the transfer portion 3b, the contact between the transfer belt 4 and the photosensitive member 1 is released, and the discharge generated in the minute gap is reduced. It is thought that it should be avoided beforehand.

Therefore, in the present invention, the roller provided on the inner or outer peripheral surface of the transfer belt 2 near the transfer section 3b is moved when the leading end of the transfer material 4 reaches the transfer section.
The contact between the transfer belt 4 and the photoconductor 1 is released, and the transfer material 4
The discharge generated by the transfer corona 3a in the minute gap between the tip of the transfer belt 2 and the transfer belt 2 is prevented beforehand. As a result, it is possible to reliably prevent the transfer material 4 from being attracted to and wound around the photoconductor 1 side.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an electrophotographic apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is a side view showing a transfer device 14 in an embodiment of the electrophotographic apparatus according to the present invention. The transfer belt 2 is movable on the inner peripheral surface of the transfer belt 2 before the transfer portion 3b in the direction in which the transfer material 4 is transported, for example, in a direction perpendicular to the transport direction of the transfer material 4 so as to apply tension to the transfer belt 2. A roller 2a for bringing the photoconductor 1 into contact with the photoconductor 1 is provided.
The roller 2a is in contact with an eccentric cam 2b attached to a drive source (not shown), and is usually at a position where tension is applied to the transfer belt 2.

The transfer material 4 is fed from the hopper 13 and
After undergoing skew correction and transfer alignment by the registration roller 8, the sheet is conveyed to the transfer section 3b. The position of the leading end of the transfer material 4 is detected by detecting means (not shown), and the transfer material 4 is detected.
The eccentric cam 2b is driven at the same time when the leading end of the roller reaches the transfer portion 3b to move the roller 2a downward. As a result, as shown by 4d in FIG. 2, the transfer belt 2 is released from contact with the photoreceptor 1, so that the transfer belt 4 has a sag 4a at the leading end of the transfer material 4 and a transfer belt 2 as shown in FIG. Small void 4b
No discharge occurs.

Further, at the same time that the leading end of the transfer material 4 passes through the transfer portion 3b, the eccentric cam 2b is driven to move the roller 2a upward, return the transfer belt 2 to the original position, and return the photosensitive member 1
Contact. In this state, the toner is reliably transferred to the transfer material 4, and the transfer material 4 does not wrap around the photoconductor 1.

As described above, the roller 2 is located near the transfer portion 3b.
By providing the transfer belt 2 with the photosensitive member 1 while providing tension to the transfer belt 2, vibration and the like due to disturbance of the transfer material 4 in the transfer unit 3 b can be prevented, and image disturbance during transfer can be prevented. Very effective.

FIG. 3 shows that the transfer material 4 is placed on the inner peripheral surface of the transfer belt 2 on the side of the transfer material 4 that is more than the transfer portion 3b in the direction in which the transfer material 4 is conveyed.
FIG. 4 is a side view showing an embodiment in which a roller 2a is provided which is movable in a direction perpendicular to the transfer direction, for example, and applies tension to the transfer belt 2 to bring the transfer belt 2 and the photosensitive member 1 into contact. The roller 2a is in contact with an eccentric cam 2b attached to a drive source (not shown), and is usually at a position where tension is applied to the transfer belt 2. The driving method of the roller 2a by the eccentric cam 2b is the same as that in FIG.

In this embodiment, as in the embodiment shown in FIG. 1, an effect of preventing the transfer material 4 from being wound around the photosensitive member 1 can be obtained.

FIG. 4 shows rollers 2a and 2c before and after the transfer section.
FIG. 4 is a diagram showing an embodiment of a system in which the transfer belt 2 is placed in contact with the photosensitive member 1 while applying tension to the transfer belt 2 and the roller 2a before the transfer portion 3b is moved by the eccentric cam 2b. In this embodiment, since the roller 2c is additionally provided in the embodiment of FIG. 1, the effect of preventing the image from being disturbed at the time of transfer is further enhanced.

FIG. 5 shows rollers 2a and 2c before and after the transfer section.
To provide contact with the photoreceptor 1 while applying tension to the transfer belt 2, and the roller 2a on the side facing the transfer portion 3b
FIG. 4 is a diagram showing an embodiment of a method of moving the に よ り by an eccentric cam 2b. In the present embodiment, since the roller 2c is additionally arranged in the embodiment of FIG. 3, the effect of preventing the image from being disturbed at the time of transfer is further enhanced.

FIG. 6 is a diagram showing an embodiment of a system in which a movable roller 2a is disposed on the outer peripheral surface side of the transfer belt 2 and is driven by an eccentric cam 2b. The roller 2 a is pulled by a spring 12 in a direction to separate the transfer belt 2 from the photoconductor 1. Normally, the eccentric cam 2b pushes up the roller 2a. When the eccentric cam 2b is rotated, the roller 2a moves the transfer belt 2 away from the photoconductor 1. According to this embodiment, the same effects as those of the embodiment of FIG. 1 can be obtained.

Since the outer peripheral surface of the transfer belt 2 is the transfer surface of the transfer material 4, it may be necessary to prevent the roller 2a from contacting the transfer surface of the transfer material 4. FIG. 7 is a diagram showing the embodiment. In the present embodiment, the central portion of the roller 2a in the axial direction has a small diameter in order to avoid contact between the roller 2a for applying tension to the transfer belt 2 and the transfer material 4.

FIG. 8 is a view showing an embodiment of a system in which the roller 2d itself for suspending the transfer belt 2 is moved by the eccentric cam 2b attached to the drive source 2e. At the same time that the leading end of the transfer material 4 reaches the transfer portion 3b, the eccentric cam 2b is driven, the suspended roller 2d is moved, and the entire transfer device 14 including the transfer belt 2 is moved downward. The same effect as that of the embodiment can be obtained.

In any of the above embodiments, the means for driving the movable roller does not necessarily need to include the eccentric cam. That is, any mechanism such as a drive rod or a link mechanism can be used as long as the mechanism retracts the roller from the rotation area of the transfer belt.

[0034]

According to the present invention, a movable roller is provided on the inner peripheral surface or the outer peripheral surface of the transfer belt of the transfer section, and the roller is moved at the same time when the leading end of the transfer material reaches the transfer section, so that the transfer belt and the photosensitive member are moved. Release of the contact of the transfer material and the discharge that occurs in the minute gap between the transfer belt and the transfer belt can be avoided.
The winding of the photoconductor around the transfer material is eliminated.

[Brief description of the drawings]

FIG. 1 is a perspective view of a transfer belt that is movable in a direction perpendicular to a transfer material transport direction on an inner peripheral surface of a transfer belt before a transfer unit in a direction in which the transfer material is transported. FIG. 2 is a side view showing a transfer device in an embodiment of the electrophotographic apparatus according to the present invention, which is provided with 2a for making contact with the transfer device.

FIG. 2 is a diagram illustrating a state in which a transfer belt is separated from a photosensitive member in the embodiment of FIG. 1;

FIG. 3 is a view showing a state in which the transfer belt is movable in a direction perpendicular to the transfer material transport direction on the inner peripheral surface of the transfer belt in a direction in which the transfer material is transported and which is opposite to the transfer unit, and applies tension to the transfer belt and the photosensitive member; FIG. 4 is a side view showing an embodiment in which a roller for contacting the contact is provided.

FIG. 4 is a diagram showing an embodiment of a system in which rollers are arranged before and after a transfer unit, a transfer belt is brought into contact with a photoconductor while applying tension, and a roller before the transfer unit is moved by an eccentric cam. It is.

FIG. 5 is a diagram illustrating an embodiment of a system in which rollers are arranged before and after a transfer unit, a transfer belt is brought into contact with a photoconductor while applying tension, and a roller facing the transfer unit is moved by an eccentric cam. It is.

FIG. 6 is a view showing an embodiment of a system in which a movable roller is arranged on the outer peripheral surface side of the transfer belt and driven by an eccentric cam.

FIG. 7 is a diagram showing an embodiment in which the central portion in the axial direction of the roller has a small diameter in order to avoid contact between the roller for applying tension to the transfer belt and the transfer material in the embodiment of FIG. 6; .

FIG. 8 is a view showing an embodiment of a system in which a roller for suspending a transfer belt itself is moved by an eccentric cam attached to a driving source.

FIG. 9 is a perspective view showing the internal structure of a general electrophotographic apparatus.

FIG. 10 is a side view illustrating a state of a leading end of a transfer material near a transfer unit in the electrophotographic apparatus illustrated in FIG. 9;

11 is a side view illustrating winding of a transfer material around a photoconductor in the electrophotographic apparatus shown in FIG. 9;

FIG. 12 is a diagram illustrating an example of an electrostatic attraction force on a transfer belt at each position of a transfer material.

[Explanation of symbols]

 Reference Signs List 1 photosensitive member 2 transfer belt 2a moving roller 2b eccentric cam 2c transfer belt pressing roller 2d transfer belt suspension roller 2e drive source 3 transfer device 4 transfer material 4a sagging 4b, 4c gap 4d gap between transfer belt and photosensitive member 5 transport guide Reference Signs List 6 Fixing roller 7 Tray 8 Registration roller 9 Cleaner 10 Discharge roller 11 Developing device 12 Spring 13 Hopper 14 Transfer device

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/16 G03G 15/14

Claims (7)

(57) [Claims] 1. An electrophotographic apparatus for electrostatically adsorbing a transfer material to a surface of an insulating transfer belt, conveying the transfer material, and transferring a toner image held on a photoreceptor surface to the transfer material, wherein an end of the transfer material is transferred. An electrophotographic apparatus comprising: a unit that releases contact between the transfer belt and the photoconductor when the transfer belt reaches the transfer unit. 2. The electrophotographic apparatus according to claim 1, wherein the release means for releasing the transfer belt and the photoconductor is provided with a movable roller provided on an inner peripheral surface side of the transfer belt near the transfer section. An electrophotographic apparatus comprising: means for driving the roller. 3. The electrophotographic apparatus according to claim 1, wherein the release means for releasing the transfer belt and the photoconductor is provided on a movable roller provided on an outer peripheral surface side of the transfer belt near the transfer portion. An electrophotographic apparatus comprising: means for driving a roller. 4. The electrophotographic apparatus according to claim 3, wherein a movable roller provided on an outer peripheral surface side of the transfer belt near the transfer section has a small-diameter portion over a width of the transfer body. An electrophotographic apparatus characterized by the following. 5. The electrophotographic apparatus according to claim 2, wherein a roller for tensioning a transfer belt at a position opposite to the movable roller with respect to the transfer unit is provided. An electrophotographic apparatus characterized by the following. 6. The electrophotographic apparatus according to claim 1, wherein the release means for releasing the transfer belt from the photoreceptor includes a roller capable of suspending and moving the transfer belt, and a means for driving the roller. An electrophotographic apparatus, characterized in that: 7. An electrophotographic apparatus according to claim 1, wherein said roller driving means comprises an eccentric cam.