JP3254271B2 - Transfer transfer 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 electrophotographic image forming apparatus, in which a toner image on an image carrier is transferred onto a transfer sheet, and the transfer sheet is transferred and separated. is there.

[0002]

2. Description of the Related Art In general, a transfer paper is brought into contact with a photosensitive drum as an image carrier to transfer a toner image formed on the photosensitive drum. After transferring the transfer paper, the transfer paper is separated (peeled) from the transfer belt. However, when the transfer paper is separated, the toner is scattered from the toner image of the transfer paper by the peeling discharge, and a polka-dot scatter is formed on the image.
In order to prevent this, a method has been adopted in which a charge removing charger is disposed in the vicinity of a portion where the transfer paper is separated from the transfer belt to remove charges on the surface of the transfer paper and the transfer belt. In order to remove the electric charge, an AC corotron (AC corona charger) is generally used when a charge elimination brush is used or when a charge elimination charger is used.

[0003]

However, in the above-mentioned conventional transfer / conveying apparatus, it is necessary to treat ozone generated at the time of charge elimination, which leaves problems such as an increase in cost. Also, when a charge removing brush is provided in place of the charge removing charger, ozone is generated, although not as much as in an AC corotron. Furthermore, unless the contact conditions, material, resistance, etc. of the static elimination brush are set strictly,
Conversely, there is also a problem that the image is disturbed by the brush pitch of the charge removing brush. Accordingly, it is an object of the present invention to solve the above-mentioned conventional problems and to provide a transfer / transport apparatus capable of minimizing the disturbance of an image and the accompanying generation of ozone.

[0004]

According to a first aspect of the present invention, there is provided a transfer belt for transferring image information held on an image carrier onto a transfer sheet, and electrostatically attracting and transferring the transfer sheet. A transfer unit that drives the transfer belt, a charging unit that applies an electric charge to the transfer belt, and a guide member that guides the transfer sheet immediately after the transfer sheet is separated from the transfer belt; The volume resistivity of
10 ⁷ to 10 ¹⁰ Ωcm , and the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is ± 10 ³
Ωcm or less, the guide member has a plurality of rib-shaped convex portions in parallel, and when the height of the rib shape is h and the radius of curvature of the rib shape is R, h ≦ 3 (mm);
It is characterized by satisfying a relationship of R ≧ 3 (mm).
According to a second aspect of the present invention, there is provided a transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt. A transfer means provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, wherein the volume specific resistance of the transfer belt is 10 ⁷ to 10 ¹⁰ Ωcm , the volume specific resistance of the guide member with respect to the volume specific resistance of the transfer belt is within ± 10 ³ Ωcm , the mounting position of the guide member is adjustable, and the mounting position of the guide member is Is switched during double-sided copy and combined copy. According to a third aspect of the present invention, there is provided a transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt. A transfer means provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, wherein the volume resistivity of the transfer belt is 1
0 ⁷ to 10 ¹⁰ Ωcm , and the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is ± 10 ³ Ωc.
m , the mounting position of the guide member is adjustable, and the mounting position of the guide member is switched according to the type of transfer paper. According to a fourth aspect of the present invention, there is provided a transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt. ,
In a transfer conveyance device provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, the transfer belt has a volume resistivity of 10 ⁷ to 10. ¹⁰ Ωcm , the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is within ± 10 ³ Ωcm , and the mounting position of the guide member is adjustable, and the mounting position of the guide member is Switching is performed according to ambient humidity and temperature.

[0005]

According to the first aspect of the present invention, when the transfer paper is separated from the transfer belt, the volume resistivity of the transfer belt is reduced.
10 ⁷ to 10 ¹⁰ Ωcm , and the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is within ± 10 ³ Ωcm, so that the resistivity of the next guide member does not greatly change with the resistivity of the transfer belt. By suppressing the electric field fluctuation of the transfer sheet and making the guide member have a rib-like shape, the area where the transfer sheet and the guide member rub against each other is made relatively small, and the back stain of the transfer sheet is prevented.

According to the second, third and fourth aspects, when the transfer paper is separated from the transfer belt, the volume resistivity of the transfer belt is 10 %.
⁷ to 10 ¹⁰ [Omega] cm, since the volume resistivity of the guide member within ± 10 ³ [Omega] cm to the volume resistivity of the transfer belt, since the resistivity of the next guide member does not vary significantly with the specific resistance of the transfer belt, a transfer The electric field fluctuation of the paper is suppressed, and the mounting position of the guide member is automatically switched according to double-sided copy, composite copy, transfer paper type, ambient humidity and temperature, so that image distortion and separation in every situation The occurrence of jam is prevented.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a photosensitive drum 1 as an image carrier
1, a transfer belt 10 is provided, and a registration roller 1 for feeding the transfer paper to the transfer belt 10 is provided on the transfer paper transport path, in front of the transfer belt 10. The transfer belt 10 drives the transfer belt 10 and is connected to a power supply 12 to reduce the contact width of the transfer belt 10 with the bias roller 6 and the photosensitive drum 11 serving as a charging unit for applying a transfer voltage. It is supported by a backup roller 7, a first ground roller 8, and a second ground roller 9 for maintaining. Further, the transfer belt 1
A push-up lever 2 for bringing 0 into contact with the photosensitive drum 11 is arranged with the solenoid 3 connected.
Further, a cleaning blade 5 for cleaning the surface of the transfer belt 10 is provided in proximity to the second ground roller 9, and the collection bottle 4 is disposed below the cleaning blade 5. Further, a guide plate 13 which is a guide member for guiding the transfer paper toward a fixing device (not shown) is provided.

In this configuration, the transfer paper which has been fed from the paper feed cassette (not shown) to the registration roller 1 and is on standby is supplied at a timing with respect to the image position on the photosensitive drum 11, and the leading end of the transfer paper is provided. Comes up to the vicinity of the contact portion between the photosensitive drum 11 and the transfer belt 10, and at the same time, the push-up lever 2 pushes up the entire transfer belt 10 by the solenoid 3 and contacts the photosensitive drum 11. Thus, when the transfer belt 10 comes into contact with the photosensitive drum 11,
Current is applied to the bias roller 6 and the backup roller 7. Since the transfer belt 10 has a medium resistance (10 ⁶ to 10 ¹² ) as the electric resistance, the charge flows and the voltage decreases as the transfer belt 10 moves toward the second ground roller 9. Further, in the vicinity of the photosensitive drum 11, a toner image having a polarity opposite to the polarity applied to the transfer belt 10 is transferred onto the transfer paper on the photosensitive drum 11 by the charge applied by the bias roller 6. In this way, the transfer paper is polarized by the charging of the applied charge, and the transfer belt 10
An electrostatic force is generated by the above-described true charge and the polarization charge of the transfer paper, and the transfer paper is attracted to the transfer belt 10. And
After the toner image is transferred, the transfer paper conveyed is gradually transferred from the second ground roller 9 to the transfer belt 10 having a medium resistance during the conveyance.
Through which the charge amount is reduced. The speed at which the amount of charge of the transfer paper is reduced is greatly affected by the resistance value R and the capacitance C of the transfer paper, and is represented by a time constant τ of τ = CR. The transfer paper having weakened electrostatic attraction is separated from the transfer belt 10 by the curvature separation of the small diameter second ground roller 9 and the transfer paper near the entrance of the fixing device, and is guided by the guide plate 13 to fix the transfer paper. Sent to the device. At this time, it is considered that the diameter of the second ground roller 9 is preferably 14 to 16 mm.

At the same time as the trailing edge of the transfer paper comes out of the nip between the photosensitive drum 11 and the transfer belt 10, the solenoid 3 is turned off and the transfer belt 10 is separated from the photosensitive drum 11. This is when the photosensitive drum 11 is not transferred.
This is to prevent the photosensitive drum 10 from deteriorating due to the contact friction between the transfer belt 10 and the transfer belt 10. Further, on the transfer belt 10 being conveyed, there is also residual toner to which toner scattered without being transferred onto the transfer paper is directly attached.
Since the charge amount is reduced by the ground roller 9, the charge is scraped off by the cleaning blade 5 and collected by the collection bottle 4.

Next, the relationship between the volume resistivity of the transfer belt 10 and the guide plate 13 and the image disturbance will be described. When an experiment was performed on this relationship, the results shown in Table 1 were obtained. Here, Rv is a volume resistivity.

[0011]

[Table 1]

In the above table, regarding the image disturbance, ○ means that no occurrence occurs, Δ means that the occurrence occurs slightly, and X means that the occurrence occurs. As is clear from Table 1, if the volume resistivity of the guide plate 13 is within approximately ± 10 ³ Ωcm with respect to the volume resistivity of the transfer belt 10, no image disturbance occurs. This is because when the transfer paper is separated from the transfer belt 10, the volume resistivity of the guide plate 13 is reduced by the transfer belt 1.
It is considered that since the volume specific resistance does not greatly change to 0, the electric field fluctuation of the transfer paper is suppressed, and image disturbance is less likely to occur. Further, as shown in FIG.
Table 2 shows the relationship between the position of the guide plate 13 and the leading end of the guide plate 13, the image disturbance, and the relationship with the separation jam when passing high-quality 45 kg paper. However, the position of the tip of the guide plate 13 is H ₁ (mm), and the intersection of the vertical line from H ₁ and the extension of the transfer belt 10 in the transfer paper transport direction is H ₂ (m).
m), the gap between the transfer belt 10 and the tip of the guide member 13 is d (mm).

[0013]

[Table 2]

In the above table, regarding the display of image disorder,
It is the same as Table 1. As is apparent from Table 2, when the line segment H ₁ H ₂ is set to 5 mm or less and the gap d is set to 2 mm or less, both the occurrence of image disturbance and the occurrence of separation jam can be prevented. This is because the smaller the line segment H ₁ H ₂ , the smaller the electric field fluctuation at the time of separation of the transfer belt 10. However, if the gap d is increased to 3 mm or more, thin paper such as high-quality 45 kg paper will This is because separation is difficult to follow following the curvature and separation jam is likely to occur, and the gap d is desirably 2 mm or less. Table 3 shows the image disturbance with respect to the volume resistivity Rv of the transfer belt 10 and the guide plate 13 when the line segment H ₁ H ₂ is 5 mm and the gap d is 2 mm.

[0015]

[Table 3]

In the above table, the display of image disturbance is the same as in Table 1. As is clear from the comparison between Table 3 and Table 1, by defining the position of the guide plate 13,
It can be seen that the occurrence of image disturbance can be prevented more.

Next, an embodiment in which the mounting position of the guide plate 13 can be adjusted will be described. As shown in FIG. 3, the guide plate 13 is attached to the apparatus main body at a fulcrum 13a so as to be rotatable in the direction of arrow A with one end 13a as a fulcrum. By the way, as shown in Table 2, in order to prevent image disturbance, the value of the line segment H ₁ H ₂ may be reduced as much as possible. However, in the case of thin paper, separation jam is likely to occur. Also, the separation jam can be suppressed by reducing the gap d between the guide plate 13 and the transfer belt 10. However, when the gap is too close, the toner on the transfer belt 10 gradually adheres to the guide plate 13 and the transfer paper 10 Since the phenomenon of contamination occurs, there is a limit in reducing the gap d. Therefore, depending on the usage of a copying machine or the like using the transfer / conveyance device, if the thin paper is not used much and there are many double-sided copies, etc., the guide plate 13 is set at a position raised counterclockwise. Conversely, when thin paper is frequently used, priority is given to prevention of separation jam, and adjustment may be made so that the guide plate 13 is used with the position of the guide plate 13 lowered clockwise. Therefore, an embodiment of the guide plate 13 will be described. For example, as shown in FIG. 4, a fulcrum 13a is pivotally supported on the apparatus main body side, and a plurality (for example, 3
The fixing holes 13b are provided, and the positions of the guide plates 13 are adjusted by appropriately selecting the fixing holes 13b according to the use condition, and the fixing holes 13b are fixed to the apparatus main body side with screws or the like.

As shown in FIG. 5, the cam 1 is located at a middle position of the guide plate 13 which is pivotally supported on the apparatus main body side at the fulcrum 13a.
The guide plate 13 is urged toward the cam 14 by attaching a coil spring 15 having one end fixed to the apparatus main body side at the other end of the guide plate 13. In this configuration, the position of the guide plate 13 is appropriately changed by rotating the cam 14 by the operation of a clutch or the like (not shown). Therefore, if the copier or the like has an automatic double-sided copy function or an automatic combining mode, the position of the guide plate 13 is lowered to prioritize separation jam prevention during single-sided copying, and the double-sided tray is used during double-sided copying or combined copying. By operating the clutch before the sheet is re-fed, and raising the position of the guide plate 13 to prevent the image from being disturbed during double-sided copying or combined copying.

Next, an embodiment in which the position of the guide plate 13 is automatically shifted in accordance with the use condition will be described. As shown in FIG. 6, a light-transmitting sensor 18 is provided at a position on the paper transport path of a call roller 17 disposed near the paper feed cassette 16.
Is provided. In this configuration, the light transmittance of the transfer paper is detected by transmitting the light to the transfer paper fed from the paper feed cassette 16 by the light transmission sensor 18 and detecting the light. As a result, the difference between the OHP sheet or the second original drawing and the other transfer paper is electrically recognized, and these are automatically discriminated. In the case of the OHP sheet or the second original drawing, it is shown in FIG. As described above, the position of the guide plate 13 is raised and used by operating the clutch to prevent the occurrence of image disorder.
In this case, the sensor for detecting the transfer paper is the light transmission type sensor 1.
The reflection type sensor is not limited to 8, and may be a reflection type sensor.

Further, as shown in FIG.
A humidity sensor (or temperature / humidity sensor) 19 is provided in the vicinity of the feeding position of No. 6. In this configuration, the humidity is detected by the humidity sensor 19, and when the humidity is equal to or lower than the predetermined humidity, the clutch is operated to guide the guide plate 13 as shown in FIG.
It is used in an elevated position to prevent image disturbance that tends to occur at low humidity.

Next, an embodiment of the shape of the guide plate 13 will be described. In general, if a large number of small-size transfer sheets having a full toner image at both ends are used, the toner at the end of the transfer sheet adheres and accumulates on the guide plate 13, and the transfer sheet of a larger size is passed. Then, the toner on the guide plate 13 may adhere to the transfer paper and cause back contamination. In order to prevent this, as shown in FIG.
A plurality of 3c (projections) are formed in parallel. When an experiment was performed using the guide plate 13 with the volume resistivity of the guide plate 13 within ± 10 ³ with respect to the volume resistivity of the transfer belt 10, an image disorder occurs depending on the size of the rib shape 13 c. I understood that. Therefore, the rib shape 1
Table 4 shows the degree of occurrence of image disorder by changing the level of the height h of 3c and the radius of curvature R of the rib shape 13c. However, the volume resistivity 10 of the transfer belt 10
The volume resistivity of the guide plate 13 is set to 10 ¹⁰ Ωc for ⁷ Ωcm.
m.

[0022]

[Table 4]

As is clear from the above table, the rib shape 13c
When the height h is 3 mm or less and the radius of curvature R of the rib shape 13c is 3 mm or more, no image disturbance occurs.
This is probably because the higher the height h of the rib shape 13c and the sharper the shape of the tip of the rib shape 13c that slides on the transfer paper, the greater the electric field fluctuation and the more likely image disturbance occurs.

[0024]

As described above, according to the first aspect of the present invention, the transfer belt has a volume resistivity of 10 ⁷ to 10 ¹⁰ Ωc.
m , since the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is set to within ± 10 ³ Ωcm , there is no need for a means for removing electricity from the transfer belt and a means for removing electricity from the transfer paper, and generation of ozone can be minimized. . Also, the electric field fluctuation of the transfer paper separating portion of the transfer belt is reduced, and the occurrence of image disturbance can be prevented. Since the guide member has a plurality of rib-shaped convex portions in parallel, the occurrence of image disturbance is reduced. Not only can be prevented, but also the back stain of the transfer paper can be prevented.

According to the second, third and fourth aspects , the volume resistivity of the transfer belt is 10 ⁷ to 10 ¹⁰ Ωcm , and the volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is ± ¹⁰ % .
Since it is within 10 ³ Ωcm, there is no need for a means for removing electricity from the transfer belt and a means for removing electricity from the transfer paper, and the generation of ozone can be minimized. Also, the electric field fluctuation of the transfer paper separating portion of the transfer belt is reduced, and the occurrence of image disorder can be prevented.
Since the mounting position of the guide member is switched according to double-sided copy, composite copy, transfer paper type, ambient humidity and temperature, it is possible to prevent image disturbance and separation jam in all situations such as user usage. And the reliability of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a transfer / transport apparatus according to the present invention.

FIG. 2 is a configuration diagram illustrating a positional relationship between a transfer belt and a guide plate.

FIG. 3 is an explanatory view showing a guide plate whose mounting position can be adjusted.

FIG. 4 is an explanatory view showing an embodiment of a guide plate whose position can be adjusted.

FIG. 5 is a schematic configuration diagram showing a guide plate position adjusting mechanism.

FIG. 6 is a schematic configuration diagram illustrating a mechanism for determining the type of transfer paper.

FIG. 7 is an explanatory diagram showing a configuration for detecting humidity.

FIG. 8 is a perspective view showing a guide plate having a rib shape.

[Explanation of symbols]

 Reference Signs List 6 driving means 6, 7 charging means 10 transfer belt 11 image carrier 13 guide member 13c rib shape

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-133087 (JP, A) JP-A-63-83777 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 15/14 101

Claims (4)

(57) [Claims] 1. A transfer belt for transferring image information held on an image carrier onto transfer paper, electrostatically attracting and transferring the transfer paper, and a driving unit for driving the transfer belt;
In a transfer conveyance device provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, the transfer belt has a volume resistivity of 10 ⁷ to 10. ¹⁰ Ωcm
The guide member has a volume resistivity of ± 10 ³ Ωcm or less with respect to the volume resistivity of the transfer belt, and the guide member has a plurality of rib-shaped protrusions in parallel. A transfer / conveying apparatus characterized by satisfying a relationship of h ≦ 3 (mm) and R ≧ 3 (mm), where h is a height and R is a radius of curvature of the rib shape. 2. A transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt;
In a transfer conveyance device provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, the transfer belt has a volume resistivity of 10 ⁷ to 10. ¹⁰ Ωcm
The volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is within ± 10 ³ Ωcm , the mounting position of the guide member is adjustable, and
A transfer / conveying apparatus characterized in that the mounting position of the guide member is switched during double-sided copying and composite copying. 3. A transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt.
In a transfer conveyance device provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, the transfer belt has a volume resistivity of 10 ⁷ to 10. ¹⁰ Ωcm
The volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is within ± 10 ³ Ωcm , the mounting position of the guide member is adjustable, and
A transfer conveyance device, wherein the mounting position of the guide member is switched according to the type of transfer paper. 4. A transfer belt for transferring image information held on an image carrier onto a transfer sheet, electrostatically attracting and transferring the transfer sheet, and driving means for driving the transfer belt;
In a transfer conveyance device provided with a charging means for applying a charge to the transfer belt and a guide member for guiding the transfer paper immediately after the transfer paper is separated from the transfer belt, the transfer belt has a volume resistivity of 10 ⁷ to 10. ¹⁰ Ωcm
The volume resistivity of the guide member with respect to the volume resistivity of the transfer belt is within ± 10 ³ Ωcm , the mounting position of the guide member is adjustable, and
A transfer conveyance device, wherein the mounting position of the guide member is switched according to the surrounding humidity and temperature.