JP3239263B2 - Transfer belt cleaning 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 apparatus for cleaning a transfer belt provided in an image forming machine such as an electrostatic copying machine, a laser printer, a facsimile, etc. And a transfer belt cleaning device provided with the fur brush.

[0002]

2. Description of the Related Art In an image forming machine such as an electrostatic copying machine, a laser printer or a facsimile, a transfer belt is used as a transfer device for transferring a toner image formed on a peripheral surface of a photosensitive drum onto transfer paper. Are widely used in practice. In a transfer device using a transfer belt as a transfer device, if a paper jam (JAM) or the like occurs in a transfer paper transport path, toner on the peripheral surface of the photosensitive drum may adhere to the surface of the transfer belt. If the transfer operation is performed in a state where the toner adheres to the surface of the transfer belt in this manner, the toner on the transfer belt adheres to the back surface of the next transfer paper, which causes the back stain of the transfer paper.

In order to solve such a problem, a transfer device using a transfer belt is provided with a cleaning device for removing toner attached to the surface of the transfer belt. As one type of this type of cleaning device, a type in which toner adhered to the surface of the transfer belt is removed by rotating the fur brush while contacting the transfer belt has been put to practical use.

[0004]

Therefore, when the surface of the transfer belt to which the toner adheres passes through the fur brush,
There is no problem if all the toner is removed by the fur brush, but it is difficult to reliably remove all the toner attached to the transfer belt. If the toner adhered to the transfer belt is not completely removed and residual toner is generated, the residual toner adheres to the back surface of the transfer paper at the next transfer and causes stain on the back of the transfer paper.

[0005] The present invention has been made in view of the above points, and its main technical problem is that when the surface of the transfer belt to which the toner adheres passes through the fur brush, the toner is not completely removed by the fur brush. An object of the present invention is to provide a transfer belt cleaning device that can prevent the residual toner from adhering to the back surface of the transfer paper at the time of the next transfer even if residual toner is generated in the transfer belt.

Another technical object of the present invention is to provide a transfer belt cleaning device which can prevent the fur brush from being clogged by the removed toner without impairing the cleaning function by the fur brush. is there.

[0007]

According to the present invention, in order to achieve the above technical object, a transfer roller is wound around a driving roller and a driven roller which are disposed parallel to each other at a predetermined interval. A cleaning device for a transfer belt disposed opposite to a photosensitive drum, the conductive fur brush being rotated while being in contact with the surface of the transfer belt, and formed on the photosensitive drum by the fur brush. A bias voltage applying means for applying a bias voltage for charging the toner with the same polarity as the charge polarity of the toner of the toner image to be formed; and a bias voltage applying means disposed in contact with the back surface of the transfer belt facing the fur brush. And a counter electrode. The bias voltage applying means is set to a voltage at which the toner can be charged to the saturation charge of the toner.

According to the present invention, a contact area between the fur brush and the transfer belt is provided with a strong electric field area where the counter electrode faces, and a counter electrode according to the present invention. A weak electric field region that is not opposed to the
A transfer belt cleaning device is provided. The strong electric field region and the weak electric field region are formed adjacent to each other in the moving direction of the transfer belt. It is desirable that the strong electric field region is formed downstream of the weak electric field region in the moving direction of the transfer belt. The fur brush may be arranged so as to face the drive roller, and the drive roller functions as a counter electrode. Further, the fur brush may be disposed so as to face the driven roller, and the driven roller may function as a counter electrode.
Other objects and features of the present invention will become apparent from the following description.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a transfer belt cleaning device constructed according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a transfer belt mechanism provided with a first embodiment of a cleaning device constructed according to the present invention. In FIG. 1, a photosensitive drum as an image carrier denoted by reference numeral 2 is rotatably disposed in a body housing of the image forming machine, and is driven to rotate in a direction indicated by an arrow A by a drive mechanism (not shown). The peripheral surface of the photosensitive drum 2 rotating in the direction indicated by the arrow A is uniformly charged to a specific polarity by a charger in a charging area (for example, +
800V). On the peripheral surface of the photosensitive drum 2 charged in this way, an electrostatic latent image of image information is formed by an exposure unit such as a laser unit in an electrostatic latent image forming area. The electrostatic latent image thus formed on the peripheral surface of the photosensitive drum 2 is developed into a toner image by a developing device in a developing area. Then, the toner image formed on the peripheral surface of the photosensitive drum 2 is transferred to a transfer sheet as described later when passing through the transfer area B.

A transfer belt mechanism 4 as a transfer device is provided in a transfer area B located below the photosensitive drum 2. The transfer belt mechanism 4 includes a drive roller 41 and a driven roller 42 disposed in parallel with each other at a predetermined interval, and is wound around the drive roller 41 and the driven roller 42 and is provided on the peripheral surface of the photosensitive drum 2. A transfer belt 43 that contacts the transfer area B; and a transfer roller 44 that is disposed to face the photosensitive drum 2 with the transfer belt 43 interposed therebetween in the transfer area B and contacts the back surface of the transfer belt 43.
And a bias voltage applying means 45 for applying a predetermined transfer bias voltage to the transfer roller 44.

The drive roller 41 and the driven roller 42
Has an axial length substantially the same as the axial length of the photosensitive drum 2, and is made of an aluminum alloy in the illustrated embodiment. Then, the drive roller 41 is rotationally driven in a direction indicated by an arrow by a driving unit (not shown), thereby operating the transfer belt 43 wound around the drive roller 41 and the driven roller 42 in a direction indicated by an arrow.

The transfer belt 43 includes the drive roller 4
1 and a width dimension substantially the same as the axial length of the driven roller 42, and in the illustrated embodiment, an endless endless member of about 0.6 mm in which urethane rubber is coated with a fluorotetrafluorocarbon resin (Teflon: trade name). It consists of a belt.
The transfer belt 43 has a volume electric resistance of 10 ⁶ to 10 ^12.
It is configured to be about Ωcm.

The transfer roller 44 is connected to the transfer belt 4
3 has an axial length that is substantially the same as the widthwise dimension of No. 3, and in the illustrated embodiment is made of foamed urethane rubber. The transfer roller 44 has a volume electric resistance of 10 ³ or more.
It is configured to be about 10 ⁴ Ω.

The bias voltage applying means 45 includes a power supply 4 for applying a predetermined bias voltage to the transfer roller 44.
51, and a constant current controller 452 disposed between the power supply 451 and the transfer roller 44. The transfer roller 44 has a charge polarity of the toner attached to the peripheral surface of the photosensitive drum 2 ( In the illustrated embodiment, a predetermined constant current (for example, +40 to +10
0 μA) is applied. The voltage at this time is +3 to +4 kV in the illustrated embodiment. In the illustrated embodiment, the driving roller 41 and the driven roller 42 are grounded.
Through the transfer belt 43 to remove the electric charge.

The illustrated transfer belt mechanism 4 includes a cleaning device 6 for removing toner adhered to the surface of the transfer belt 43. The cleaning device 6
A fur brush 61 disposed below the transfer belt 43 constituting the transfer belt mechanism 4 and rotated while contacting the surface of the transfer belt 43; and a bias voltage applying means for applying a predetermined bias voltage to the fur brush 61 62,
A counter electrode 63 disposed opposite to the fur brush 61 with the transfer belt 43 interposed therebetween;
1 is a toner scraping member 64 for dropping the toner removed from the surface of the transfer belt 43 from the fur brush 61.

The fur brush 61 includes a rotating shaft 611 made of metal and a conductive brush portion 612 mounted on the rotating shaft 611. The shaft is substantially the same as the width of the transfer belt 43 in the width direction. Direction length. The brush portion 612 is formed by implanting conductive polyester fibers on a conductive cloth, and is adhered to the peripheral surface of the rotating shaft 611 by a conductive double-sided adhesive tape. In the illustrated embodiment, the electrical resistance of the polyester fiber constituting the brush portion 612 is set to 10 ³ to 10 ⁴ Ω. The fur brush 61 thus configured is
Driving means (not shown) is rotated so as to move in the direction indicated by the arrow, that is, in the direction opposite to the moving direction of the transfer belt 43 at the contact portion with the transfer belt 43.

The bias voltage applying means 62 includes a power supply 621 for applying a predetermined bias voltage to the fur brush 61, and a constant current controller 622 disposed between the power supply 621 and the fur brush 61. The fur brush 61 has a predetermined constant current (eg, −) having the same polarity (minus polarity in the illustrated embodiment) as the charged polarity (minus polarity in the illustrated embodiment) of the toner.
5 to −40 μA). The voltage at this time is about -1.0 to -1.5 kV in the illustrated embodiment, and is desirably set to a voltage that can charge the toner to the saturation charge of the toner.

The counter electrode 63 is connected to the transfer belt 43.
Is arranged in contact with the back surface of the, and is grounded.

The toner scraping member 64 has a width dimension substantially equal to the axial length of the fur brush 61, and one end thereof is inserted into the brush portion 612 of the fur brush 61. .

The transfer belt mechanism provided with the transfer belt cleaning device in the embodiment shown in FIG. 1 is configured as described above, and its operation and effect will be described below. The transfer paper P fed by a transfer paper feeding means (not shown) is conveyed from the right side to the transfer area B in the figure. When the transfer paper P conveyed to the transfer area B passes between the photosensitive drum 2 and the transfer belt 43, the transfer paper P is attached to the peripheral surface of the photosensitive drum 2 by the bias voltage applying unit 45. By applying a predetermined bias voltage having a polarity opposite to the charged polarity of the toner via the transfer roller 44, the toner image attached to the peripheral surface of the photosensitive drum 2 is transferred to the transfer paper P. The transfer paper P on which the toner image has been transferred in this manner is conveyed leftward in the figure by the transfer belt 43, and is heated and fixed by fixing means (not shown) disposed on the left side of the transfer belt mechanism 4 in the figure. You.

If the transfer sheet P is not conveyed to the transfer area B due to the occurrence of JAM or the like during the image forming operation described above, the toner on the peripheral surface of the photosensitive drum 2 adheres to the transfer belt 43. The transfer belt 43 to which the toner has been attached in this way moves in the direction indicated by the arrow, and the toner attached to the transfer belt 43 is removed by the fur brush 61 of the cleaning device 6. The toner removed from the surface of the transfer belt 43 is dropped from the fur brush 61 by the toner scraping member 64 and stored in a toner receiver (not shown).

There is no problem if all the toner adhering to the transfer belt 43 can be removed by the fur brush 61. However, if residual toner is generated on the transfer belt 43 without being removed, the residual toner is removed during the next transfer. Transfer paper P
Adheres to the back surface of the transfer paper and becomes the back stain of the transfer paper. However, in the illustrated embodiment, the fur brush 6
Since a bias voltage having the same polarity as the charging polarity of the toner is applied to 1 by the bias voltage applying means 62, the residual toner is further charged through the fur brush 61. The amount of charge that charges the residual toner is, as described above, the saturated charge of the toner (for example, −30 μc /
g), and the voltage and current of the bias voltage applying unit 62 are set so that the residual toner can be charged to the saturation charge. In this way, when the amount of charge of the residual toner increases, the transfer area B
At the transfer roller 4 by the bias voltage applying means 45.
4 increases the electric attraction force to the transfer belt 43 to which a bias voltage having a polarity opposite to the charge polarity of the toner is applied, so that the residual toner may not adhere to the back surface of the transfer paper P at the next transfer. Absent.

Next, a second embodiment of the transfer belt cleaning apparatus constructed according to the present invention will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 2, the same members as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 described above in the positional relationship between the opposing electrode 63 and the fur brush 61 constituting the cleaning device 6. The counter electrode 63 in the embodiment shown in FIG. 2 is disposed on the upstream side in the moving direction of the transfer belt 43 from the approximate center of the contact area (FB) between the fur brush 61 and the transfer belt 43. For this reason, in the contact area (FB),
A strong electric field region (S) facing the counter electrode 63 and a weak electric field region (W) not facing the counter electrode 63 are formed.

The cleaning device 6 configured as described above
In, the removal of the toner attached to the surface of the transfer belt 43 is mainly performed in the weak electric field region (W). That is, since the electric field is weak in the weak electric field region (W), there is almost no electric repulsion acting between the fur brush 61 and the toner, and the original cleaning function of the fur brush is exhibited. On the other hand, in the strong electric field region (S), the fur brush 61 and the counter electrode 6
3, the electric repulsion acting between the fur brush 61 and the toner becomes stronger, so that the toner removed from the transfer belt 43 by the fur brush 61 is clogged between the eyes of the fur brush 61. The toner is scraped off by the toner scraping member 64 with the rotation of the fur brush 61 without causing clogging. For example, as in the embodiment shown in FIG. 1, the counter electrode 63 is disposed over the entire touch area (FB).
Although the function of preventing the fur brush from being clogged by the toner is sufficiently exhibited, there is one aspect that the intrinsic cleaning function of the fur brush is impaired. The reason for this is that the toner which is supposed to be scraped cannot be scraped or the toner which has been scraped once cannot be removed due to the strong electrical repulsion between the toner and the fur brush which the fur brush is trying to scrape off from the surface of the transfer belt. This is because the particles are scattered by the electric repulsion and adhere to the transfer belt again. However, in the embodiment shown in FIG. 2, the strong electric field region (S) and the weak electric field region (W) are formed in the contact region (FB) between the fur brush 61 and the transfer belt 43 as described above. ,
In the weak electric field region (W), a cleaning function for mainly removing toner is exhibited, and in the strong electric field region (S), a function for preventing clogging is exhibited. Therefore, it is possible to obtain a transfer belt cleaning device that can prevent the fur brush from being clogged by the removed toner without impairing the cleaning function. In the illustrated cleaning device 6, the ratio between the cleaning function and the clogging prevention function can be adjusted by changing the ratio between the weak electric field region (W) and the strong electric field region (S). In particular, when a flat electrode plate is used as the counter electrode 63 as in the embodiment shown in FIG. 2, the degree of freedom of the adjustment is large.

If the toner adhered to the surface of the transfer belt 43 is not removed by the fur brush 61 when passing through the contact area (FB), the residual toner is added to the strong electric field area (S). When the toner passes through the fur brush 61, the electric charge of the same polarity as the toner is charged to the substantially saturated electric charge of the toner.
Increases the electric attraction force to the transfer belt 43 to which a bias voltage having a polarity opposite to the charge polarity of the toner is applied, so that the residual toner may not adhere to the back surface of the transfer paper P at the next transfer. Absent.

Next, a third embodiment of the cleaning device constructed according to the present invention will be described with reference to FIG. In FIG. 3, the same members as those in the embodiments shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 described above in the positional relationship between the opposing electrode 63 and the fur brush 61 constituting the cleaning device 6. The counter electrode 63 in the embodiment shown in FIG. 3 is disposed on the downstream side in the movement direction of the transfer belt 43 from the approximate center of the contact area (FB) between the fur brush 61 and the transfer belt 43. For this reason, in the contact area (FB),
The strong electric field region (S) facing the counter electrode 63 is the counter electrode 6
The transfer belt 43 is formed on the downstream side in the moving direction of the transfer belt 43 from the weak electric field region (W) not facing the transfer belt 3. Therefore, in the weak electric field region (W) on the upstream side in the moving direction of the transfer belt 43, the toner adhered to the surface of the transfer belt 43 is removed by the fur brush 61, and the residual toner that has not been removed at this time is removed When passing through (S), a charge having the same polarity as the charge polarity of the toner is charged via the fur brush 61. For this reason, it is possible to reliably charge the slightly residual toner to the substantially saturated charge of the toner by the fur brush 61 while passing through the strong electric field region (S). Since the attraction force increases, the effect of preventing the transfer paper from adhering to the back surface at the time of the next transfer becomes more reliable.

Next, a fourth embodiment of the cleaning device constructed according to the present invention will be described with reference to FIG. In FIG. 4, the same members as those in the embodiments shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted. In the embodiment shown in FIG. 4, the fur brush 61 constituting the cleaning device 6 is disposed at a position facing the drive roller 41 of the transfer belt mechanism 4, and the drive roller 41 functions as a counter electrode. It is. Also in this embodiment, the contact area (FB) between the fur brush 61 and the transfer belt 43 includes:
A strong electric field region (S) facing the drive roller 41 as the counter electrode and a weak electric field region (W) not facing the drive roller 41 as the counter electrode are formed, as in the embodiment shown in FIG. The operation and effect of the invention can be obtained. Further, in the embodiment shown in FIG. 4, the driving roller 41 of the transfer belt mechanism 4 is configured to function as a counter electrode, so that the number of components can be reduced and the manufacturing cost of the apparatus can be reduced.

Next, a fifth embodiment of the cleaning device constructed according to the present invention will be described with reference to FIG. In FIG. 5, the same members as those in the embodiments shown in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof will be omitted. In the embodiment shown in FIG. 5, the fur brush 61 constituting the cleaning device 6 is disposed at a position facing the driven roller 42 of the transfer belt mechanism 4, and the driven roller 42 functions as a counter electrode. It is. In this embodiment, the contact area (FB) between the fur brush 61 and the transfer belt 43 includes:
A strong electric field region (S) facing the driven roller 42 as the opposing electrode and a weak electric field region (W) not opposing the driven roller 42 as the opposing electrode are formed, as in the embodiment shown in FIG. The operation and effect of the invention can be obtained. In the embodiment shown in FIG. 5, since the strong electric field region (S) is formed on the downstream side in the moving direction of the transfer belt 43 from the weak electric field region (W), the embodiment is similar to the embodiment shown in FIG. First, in the weak electric field region (W) on the upstream side in the moving direction of the transfer belt 43, the toner attached to the surface of the transfer belt 43 is removed by the fur brush 61. Fur brush 6 when passing
1, the electric charge having the same polarity as the charged polarity of the toner is charged, so that the fur brush 61 can reliably charge the residual toner to substantially the saturated charge of the toner while passing through the strong electric field region (S). As a result, the electric attraction force to the transfer belt 43 is increased, so that the effect of preventing the transfer paper from adhering to the back surface at the time of the next transfer becomes more reliable.

[0030]

Since the transfer belt cleaning device according to the present invention is constructed as described above, it has the following functions and effects.

That is, according to the present invention, the fur brush having conductivity which is rotated in contact with the surface of the transfer belt, and the same polarity as the charge polarity of the toner of the toner image formed on the photosensitive drum on the fur brush. A bias voltage applying means for applying a bias voltage for charging the toner with a polarity; and a counter electrode disposed in contact with the back surface of the transfer belt facing the fur brush, so that the toner adheres to the transfer belt. Even when the toner is not removed by the fur brush and residual toner is generated on the transfer belt, the residual toner is charged with a charge having the same polarity as the charged polarity of the toner. As a result, the residual toner does not adhere to the back surface of the transfer paper P during the next transfer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a transfer belt mechanism including a first embodiment of a cleaning device configured according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating a transfer belt mechanism including a second embodiment of a cleaning device configured according to the present invention.

FIG. 3 is a schematic configuration diagram showing a transfer belt mechanism including a cleaning device according to a third embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a main part of a transfer belt mechanism including a cleaning device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a main part of a transfer belt mechanism including a cleaning device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 2: photosensitive drum 4: transfer belt mechanism 41: drive roller 42: driven roller 43: transfer belt 44: transfer roller 45: bias voltage applying means 46: toner scraping member 451: power supply 452: constant current controller 6: cleaning Apparatus 61: Fur brush 611: Rotation axis of fur brush 612: Brush part 62: Bias voltage applying means 63: Counter electrode 621: Power supply 622: Constant current controller

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-209145 (JP, A) JP-A 8-69231 (JP, A)

Claims (7)

(57) [Claims] An apparatus for cleaning a transfer belt wound around a driving roller and a driven roller disposed in parallel with each other at a predetermined interval and disposed opposite to a photosensitive drum in a transfer area, A fur brush having conductivity which is rotated in contact with the surface of the transfer belt; and the same polarity as the charged polarity of the toner of the toner image formed on the photosensitive drum on the fur brush.
A bias voltage applying means for applying a bias voltage for charging the toner with a charge, a counter electrode disposed in contact with the back surface of the transfer belt facing the fur brush,
A cleaning device for a transfer belt, comprising: 2. The transfer belt cleaning device according to claim 1, wherein said bias voltage applying means is set to a voltage capable of charging the toner to a saturation charge of the toner. 3. The contact area between the fur brush and the transfer belt includes a strong electric field area where the counter electrode faces and a weak electric field area where the counter electrode does not face.
The transfer belt cleaning device according to the above. 4. The high electric field region and the low electric field region are formed adjacent to each other in a direction in which the transfer belt moves.
The transfer belt cleaning device according to the above. 5. The transfer belt cleaning device according to claim 4, wherein the strong electric field region is formed downstream of the weak electric field region in the moving direction of the transfer belt. 6. The transfer belt cleaning device according to claim 1, wherein the fur brush is disposed to face the driving roller, and the driving roller functions as the counter electrode. 7. The transfer belt cleaning device according to claim 1, wherein the fur brush is disposed to face the driven roller, and the driven roller functions as the counter electrode.