JP3355721B2 - 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 image forming apparatus for developing and visualizing an electrostatic latent image, for example, a transfer apparatus such as a copying machine and a laser beam printer.

[0002]

2. Description of the Related Art In a transfer apparatus using an electrophotographic technique, there is a method in which a transfer material formed of a dielectric belt or an insulating drum is used for both transferring and transferring a sheet.

In this method, a cleaning mechanism is required in the following cases.

(1) When a toner image is transferred onto a transfer material When a sheet is stopped due to a jam or other obstacle during the conveyance and the conveyed sheet does not reach the transfer section, it is formed on a photosensitive member. The transferred toner image may be directly transferred onto a transfer material instead of paper.

[0005] This is because when the machine detects a failure such as a jam and the control unit issues a stop command, the photosensitive drum, the drive motor for the transfer material and the power supply to the transfer unit are stopped until the energization of the transfer unit is actually stopped. This occurs because the toner image formed on the transfer portion reaches the transfer portion.

In addition, when printing is performed on the edge of the sheet (front, rear, left and right), the sheet may be shifted due to the accuracy of sheet running, and the toner may be transported to the transfer unit.

In this case, a toner image remains on the transfer material near the outside of the sheet.

(2) When fogging toner is transferred When a sheet smaller than the width of the transfer material is used, there is no latent image in the non-sheet passing area (the area where the belt does not contact the sheet), but the background image (Fogging) in which toner adheres to the toner.

Therefore, the fog toner in the non-sheet passing area is transferred to the transfer material.

In addition, when cut paper is used as the paper, there is an interval between the traveling paper and the paper.

As in the non-sheet passing area, since fog toner is generated between the sheets, the fog toner is transferred onto the transfer material.

(3) In the case where paper dust adheres to the transfer material The surface of the paper is rubbed by sliding of rollers of a transport system, and paper dust is generated.

If a large amount of paper dust adheres to the transfer material and accumulates in a large amount, the adhesion between the paper and the transfer material deteriorates, which causes a drum wrap (a phenomenon in which the paper is attracted to the photoconductor).

In general, the above-described method for removing dirt includes a method of pressing an edge of an elastic blade made of urethane rubber or the like against a transfer material surface to remove toner, or a method of rotating a fur brush at high speed to mechanically remove toner. There is a method to remove.

[0015]

However, the elastic blades and fur brushes used in the conventional transfer device cleaning mechanism always come into contact with the running transfer material when the transfer device is driven, so that they are relatively early. Wear and deterioration, and its cleanability is deteriorated.

When the cleaning property of the transfer material is deteriorated, the toner image adhered on the transfer material cannot be cleaned. Or the suction force between the transfer material and the sheet is reduced, which causes the aforementioned drum wrap or the like.

An object of the present invention is to provide a transfer apparatus having a cleaning mechanism capable of stably maintaining the transfer material for a longer period of time when cleaning residual toner on the transfer material as compared with the related art. .

[0018]

SUMMARY OF THE INVENTION The object of the present invention is to provide a transfer material.
And transfer the transfer material onto the toner image carrier via the transfer material.
Press to transfer charge of opposite polarity to toner on the back of transfer material
Formed on the toner image carrier by applying
Transfer device that transfers the transferred toner image onto the transfer material.
After the transfer step, the toner remaining on the surface of the transfer material,
Opposite polarity to the charge on the surface of the toner image carrier on foreign matter such as paper dust
A charge providing means for providing a charge of
A transfer material drive that faces the charge applying means with the transfer material interposed therebetween.
A moving member, and when the printing is not performed, the charge applying means switches the
Make the current value flowing into the copying material drive member greater than during printing
It is achieved by that.

[0019]

According to the present invention having the above-described structure, the toner remaining on the surface of the transfer material after the completion of the transfer step, at the time of non-printing such as at the time of a recovery operation after a failure such as a jam or at the time of an initialization operation by turning on the power supply, Foreign matter such as paper dust, that is, foreign matter such as toner and paper dust to which a charge having a polarity opposite to the charge on the surface of the toner image carrier is applied is moved to the toner image carrier side by the movement of the transfer belt, and the existing toner image is removed. It is cleaned by a carrier surface cleaning cleaner.

[0020]

【Example】

(Embodiment 1) An embodiment in which the present invention is applied to a laser beam printer employing electrophotography will be described with reference to FIG.

After the surface of the photoconductor 1 is uniformly charged by corona discharge of the charger 2, a latent image is formed by a light source 3 such as a semiconductor laser or an LED, and toner is formed on the photoconductor 1 by a developing device 4. Adhere to.

After the paper 5 is conveyed by a transfer belt 6 made of a dielectric material having both a paper conveyance function and a transfer function, the toner image on the photoreceptor 1 is transferred by the transfer device 7 to the paper 5.
Is transferred to

Thereafter, the toner image on the sheet 5 is fixed by the fixing roll 8, and the transferred toner image on the photoreceptor 1 is cleaned by the cleaner 11 via the precharge 9 and the erase lamp 10, and then the next image is formed again. Move on to the process.

The transfer belt 6 is held at both ends by a driving member 12 and a sliding member 13, and is rotated by a motor (not shown) provided near the driving member 12.

The paper 5 conveyed by the transfer belt 6 has a high voltage (high-voltage power supply 1) having a polarity opposite to that of the toner (plus) at a portion where the transfer belt 6 and the photosensitive member 1 are in contact.
The toner image on the photoreceptor 1 is transferred by the transfer device 7 to which the high voltage from (4) is applied.

Thereafter, the paper 5 is peeled off from the transfer belt 6, and the peeling discharge generated at this time causes a phenomenon in which the toner is scattered, thereby causing contamination in the apparatus.

In order to prevent this, the driving member 12 and the discharger 15 have opposite polarity (plus) to the toner, respectively.
(High voltage from the high-voltage power supplies 17 and 16) is applied to apply a charge having a polarity opposite to that of the toner on the back surface of the sheet 5 to prevent the toner from scattering.

As will be described later, the high-voltage power supply 17 for applying a voltage to the driving member 12 is switchable, and a high voltage is normally applied to the driving member 12.

As described above, since the transfer belt 6 has both the sheet conveying function and the transfer function, there is usually no need for cleaning.

However, when the toner image is transferred onto the transfer belt 6 for any reason, cleaning is required.

Here, the mechanism for cleaning the transfer belt 6 according to the present embodiment will be described in detail with reference to FIG.

The toner image 18 transferred onto the transfer belt 6 due to a jam or other obstacle is unstable because the polarity of the transfer belt 6 is opposite (plus) to the toner as shown in FIG. 2A. However, the polarity is almost uniform (minus).

A high voltage (high voltage from a high-voltage power supply 16) having a polarity opposite to that of the toner (high voltage) is applied to a discharger 15 provided near the driving member 12.
By switching the high-voltage power supply 17 in the opposite direction to the normal operation, a large amount of positive current flows from the discharger 15 to the drive member 12 via the grounding portion.

Due to the flowing current, the minus toner image adhered to the surface of the transfer belt 6 is inverted to plus as shown in FIG.

As shown in FIG. 2C, since the transfer belt 6 and the photoconductor 1 are in contact with each other with a constant nip width (W) indicated by reference numeral 19, the inverted positive toner image 2 is inverted.
0 moves to the photoreceptor 1 side which is charged to a negative potential in the transfer section, and is cleaned by the cleaner 11.

Normally, after a failure such as a jam, a process for removing these is performed, and then a recovery operation is performed.

This is done by cleaning the toner image remaining on the photoreceptor 1 and the transfer belt 6 due to an obstacle such as a jam, and driving each mechanism unit to check whether there is any abnormality in each process before the next printing. In this case, the operation is confirmed. Here, the charger 2, the precharge 9, the erase lamp 10, the cleaner 11, and the discharger 15 are in an activated state, and the exposure and development processes are stopped (however, the developing machine 4 is driven and a developing bias is applied). The voltage is OFF).

Then, the toner image transferred onto the transfer belt 6 is cleaned by moving to the photosensitive member 1 side during the recovery operation as described above.

As means for increasing the current flowing into the driving member 12, there are other means such as the discharger 15
May be increased, or the polarity of the high voltage power supply 17 may be switched.

(Embodiment 2) FIG. 3A shows that the current flowing from the transfer unit 7 to the photosensitive member 1 is increased during non-printing such as during a recovery operation after a failure such as a jam or an initialization operation by turning on the power. It is something to do.

As shown in FIG. 3B, the toner image 20 that has been inverted to the positive direction on the transfer belt 6 is
A current flows by an electric field formed therebetween, and a force acts in a direction in which the toner image 20 moves to the photoconductor 1 side.

Therefore, by increasing the voltage or current applied to the transfer unit 7, the adhered toner can easily move to the photosensitive member 1 side, and the cleaning property of the transfer belt 6 is improved.

As described above, when a toner image is generated on the belt 6 due to an obstacle such as a jam, the cleaning current of the transfer belt 6 is improved by increasing the current flowing from the transfer unit 7 to the photosensitive member 1 during non-printing. Then, the back side of the paper is hardly stained.

Similarly, by increasing the current flowing in advance in response to the passage of the fogging toner between the running paper sheets, the cleaning performance of the fogging toner can be improved.

(Embodiment 3) The current flowing from the discharger 15 into the drive member 12 changes greatly depending on the ambient temperature and humidity.

This is because the electric resistance of the transfer belt 6 increases at low temperature and low humidity.

FIG. 4A shows a difference in current flowing into the driving member 12 due to a change in temperature and humidity. Even if the current of the power supply applied to the discharger 15 is the same,
Depending on the value of the temperature and the humidity, it becomes difficult for the current to flow through the driving member 12, and in such a case, the polarity of the toner is hardly inverted.

That is, in the low-temperature and low-humidity region indicated by oblique lines in FIG. 4B, the toner is hardly moved from the transfer belt 6 to the photosensitive member 1, so that the cleaning property is deteriorated and the back side of the paper is stained.

FIG. 5 shows that the transfer device is provided with sensors 21 and 22 for detecting temperature and humidity, respectively, and the current flowing into the drive member 12 is controlled based on the detected values.

The temperature and humidity sensors 21 and 22 are provided around the transfer device.
The detected values are converted into digital signals by the output converters 23 and 24, respectively, and sent to the control unit 25.

When the temperature and humidity change and the cleaning performance falls within a certain range indicated by hatching in FIG. 4B, the driving member 1
By controlling the high-voltage power supply 26 of the discharger 15 so as to increase the current flowing into the transfer belt 2, the cleaning property of the transfer belt 6 is maintained even in an environment where the charge amount of the toner is unlikely to be inverted, such as at low temperature and low humidity. be able to.

The control of the inflow current may be performed by changing the voltage of the high voltage power supply 17 instead of the above, and instead of detecting the temperature and humidity, the electric resistance and surface charging voltage of the transfer belt 6 may be detected. .

(Embodiment 4) Adhered toner moves in the nip area between the photoreceptor 1 and the transfer belt 6, and the longer the nip area, the longer the contact time between the two. Is set to a certain value in consideration of the drum wrap and transfer efficiency.

Therefore, when the nip width (W) 19 between the photoreceptor 1 and the transfer belt 6 is larger than that during the printing, in addition to the above-described increase in the current flowing into the driving member 12 during the non-printing, the transfer is increased. The cleaning property of the belt 6 is further improved.

In FIG. 6A, the nip width 19 between the photosensitive member 1 and the transfer belt 6 at the time of toner transfer is set to (W) by holding members 27 and 28, and the holding members 27 and 28 Each of the holding members 27 and 28 is fixed by an eccentric cam (not shown) in each of the holding members 27 and 28. By rotating these eccentric cams, the holding members 27 and 28 can move upward.

That is, at the time of a non-printing operation such as a recovery operation after a failure such as a jam or an initialization operation by turning on the power,
Holding member 2 by a stepping motor (not shown)
By rotating the eccentric cams 7 and 28 by 180 °, the holding members 27 and 28 are moved upward, and the transfer belt 6 is lifted, and as shown in FIG. The nip width 19 expands to (W1).

As described above, at the time of non-printing, in addition to the above-described increase of the current flowing into the driving member 12, the nip width 19 between the photosensitive member 1 and the transfer belt 6 is made larger than that at the time of printing (W). As a result (W1), the cleaning property of the transfer belt 6 is further improved.

(Embodiment 5) FIG. 7 shows a case where a toner image is transferred onto the transfer belt 6 due to an obstacle such as a jam or when the transfer belt 6 is detached from the paper when printing to the end of the paper.
When the toner image is transferred on the transfer belt 6, the cleaning performance of the transfer belt 6 is further improved by adding a cleaning mechanism in addition to the increase in the current flowing into the driving member 12 described above.

The cleaning mechanism comprises an elastic blade 29 made of urethane rubber, phosphor bronze, or the like, and a mounting member 30 for holding the elastic blade 29.

At the time of normal printing, as shown in FIG.
The transfer belt 6 and the elastic blade 29 are in a non-contact state.

When a toner image is generated on the transfer belt 6 due to a jam or the like, or when printing is performed up to the edge of the sheet, the sheet is shifted due to the paper running accuracy, and the toner is conveyed to the transfer unit. When the toner image remains near the outside of the sheet, the elastic blade 29 is pressed against the transfer belt 6 as shown in FIG.

The details of driving the mounting member 30 of the elastic blade 29 are omitted, but by rotating the mounting member 30 by a predetermined angle by a stepping motor, the elastic blade 29 comes into contact with the transfer belt, and the mounting member 30 is moved as described above. The elastic blade 29 and the transfer belt 6 are brought into a non-contact state by rotating the transfer belt 6 by a predetermined angle in the reverse direction.

At the time of operation after recovery from a failure such as a jam,
That is, during non-printing or when printing is performed up to the edge of the sheet, the toner 33 adhered to the transfer belt 6 is removed by the discharger 1
After passing through 5, it is dropped to some extent by the elastic blade 29 and accumulated in the waste bottle 34.

The remaining toner 35 that could not be cleaned by the elastic blade 29 is positively charged by passing through the discharger 15 and moves to the photoconductor 1 side.

For this reason, there is an advantage that the mounting accuracy of the elastic blade 29 does not need to be increased and the control as in the second embodiment is not required.

Further, as described above, the elastic blade 29 is used only at the time of non-printing or printing to the end of the sheet, and is not used at any other time. In other words, the problem of the above problem, that is, the problem that the elastic blade is worn and deteriorated relatively early due to the constant contact with the running transfer material when the transfer device is driven can be eliminated, and the life of the elastic blade can be extended.

In this embodiment, the cleaning member is an elastic blade. However, the cleaning member is not limited to this and may be a brush.

In the first to fifth embodiments, the cleaning of the transfer belt 6 for both transferring the toner image to the paper and transporting the paper has been described. However, the toner image is temporarily transferred from the photosensitive member to the intermediate transfer member. The present invention can also be applied to cleaning of an intermediate transfer medium in a method of finally transferring this to a sheet.

[0069]

According to the present invention, when the residual toner on the transfer material is cleaned, there is an effect that the cleaning of the transfer material can be stably maintained for a long period of time as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the internal structure of a laser beam printer equipped with a transfer device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a cleaning mechanism according to the present invention.

FIG. 3 is a cross-sectional view of a transfer device according to a second embodiment of the present invention.

FIG. 4A is a diagram for explaining the influence of a change in ambient temperature and humidity on a power supply current applied to a discharger indicated by reference numeral 15 in each embodiment and a current flowing from the discharger 15 to a driving member 12; is there. (B) is a diagram for explaining the relationship between ambient temperature and humidity and cleaning characteristics.

FIG. 5 is a sectional view of a transfer device according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a transfer device according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view of a transfer device according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 2 ... Charger, 3 ... Light source, 4 ... Developing machine, 5 ...
Paper, 6 transfer belt, 7 transfer device, 8 fixing roll,
9: Precharge, 10: Erase lamp, 11: Cleaner, 12: Transfer belt driving member, 13: Transfer belt sliding member, 14: High voltage power supply, 15: Discharger, 1
6, 17 high-voltage power supply, 18 toner image, 19 nip width (W, W1), 20 inverted plus toner image, 21
... temperature sensor, 22 ... humidity sensor, 23, 24 ... output converter, 25 ... control unit, 26 ... high voltage power supply, 27, 28 ... nip width holding member, 29 ... elastic member, 30 ... elastic blade mounting member, 31 ... Fog toner, 32: paper powder, 33: toner adhered on the transfer belt 6, 34: waste bottle, 35:
Remaining toner that could not be cleaned by the elastic blade 29.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinji Asai 1060 Takeda, Katsuta-shi, Ibaraki Pref.Hitachi Koki Co., Ltd. (72) Inventor Yasuo Kikuchi 1060 Takeda, Katsuta-shi, Ibaraki Pref.Hitachi Koki Co., Ltd. (72) Inventor Masato Miwa 1060 Takeda, Katsuta-shi, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (56) References JP-A-63-247779 (JP, A) JP-A-1-105980 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) G03G 15/16-15/16 103

Claims (8)

(57) [Claims] A transfer material that is conveyed, pressed against the toner image bearing member via the transfer material, and a charge having a polarity opposite to that of the toner is applied to the back surface of the transfer material by a transfer device;
In a transfer device for transferring a toner image formed on a toner image carrier onto a material to be transferred, foreign matters such as toner and paper dust remaining on the surface of the transfer material after the transfer process are completed. And a charge providing means for providing a charge having a polarity opposite to that of the transfer material.
A transfer material driving member facing the means, and when printing is not performed,
Current value flowing into the transfer material driving member from charge applying means
A transfer device larger than at the time of printing . 2. The method according to claim 1, wherein said charge applying means is a corona charger.
2. The transfer device according to claim 1, wherein: Wherein a voltage is applied between the transfer material driving member and the ground at the time of printing, when not printing, the transfer material driving member transfer device according to claim 1, wherein configured to connect to ground the. 4. The transfer device has a mechanism for detecting temperature and humidity. Based on the detected value, the current value flowing from the charge applying means to the transfer material driving member during non-printing is smaller than that during printing. 2. The transfer device according to claim 1 , wherein the transfer device is configured to perform large control. It is 5. A transfer device includes a mechanism for detecting the electrical resistance of the transfer material, by the detection value, when not printing, the electrostatic
Transfer device configured claims 1, wherein to control larger than when printing a current value flowing into the transfer material driving member from load imparting means. It is 6. The transfer device includes a mechanism for detecting the surface charging voltage of the transfer material, by the detection value, when not printing, front
The transfer device of claim 1, wherein configured to control larger than when printing a current value flowing into the transfer material driving member from the serial charging unit. 7. A nip width between a toner image carrier and a transfer material is made variable, and a nip width between the toner image carrier and the transfer material during non-printing is made larger than a nip width during printing. The transfer device according to any one of claims 1 to 6 , configured as described above. 8. The transfer device includes a cleaning member, and transfers the cleaning member only during an operation after recovery from a failure such as a jam, during non-printing such as an initialization operation by turning on a power source, and during printing of a sheet edge. 2. The structure according to claim 1, wherein the material is in contact with the material.
The transfer device according to any one of claims 1 to 7 ,