KR20080012581A - Intermediate transfer unit for color image forming apparatus - Google Patents

Abstract

An intermediate transfer unit for a color image forming apparatus is provided to compensate the tension of a transfer belt in real time through a tension roller and align rollers, thereby maintaining uniformly the rotation speed of the transfer belt. An intermediate transfer unit for a color image forming apparatus comprises a transfer belt(100), a driving roller(200), plural pressure rollers, plural transfer roller and a pressure elastic force adjusting unit(310,350). The transfer belt has a belt surface(110). The driving roller rotates the transfer belt. The plural pressure rollers provide a pressure elastic force to the belt surface in different directions. The plural transfer rollers contact the belt surface of the transfer belt. The pressure elastic force adjusting unit adjusts the pressure elastic force of the pressure rollers.

Description

Intermediate transfer unit for color image forming apparatus {INTERMEDIATE TRANSFER UNIT FOR COLOR IMAGE FORMING APPARATUS}

1 is a view showing a conventional color image forming apparatus.

2 is a perspective view showing an intermediate transfer unit for a color image forming apparatus of the present invention.

3 is a side view schematically showing an intermediate transfer unit for a color image forming apparatus according to an embodiment of the present invention.

4 is a side view schematically showing an intermediate transfer unit for a color image forming apparatus according to another embodiment of the present invention.

5 is a block diagram showing a belt tension control method using the intermediate transfer unit for the color image forming apparatus of the present invention.

** Explanation of Signs of Major Parts of Drawings **

100: transfer belt

310: tension roller

350: alignment roller

610: the first elastic member

620: second elastic member

The present invention relates to an intermediate transfer unit of a color image forming apparatus, and more particularly, to an intermediate transfer unit of a color image forming apparatus having a belt tension control unit for correcting it when the transfer belt is extended or meandering. It is about.

In general, an electrophotographic color image forming apparatus such as a laser beam printer, a digital copier, or a multifunction printer scans a laser beam on a plurality of photosensitive media to form an electrostatic latent image, and applies a developer to the photosensitive medium on which the electrostatic latent image is formed, thereby making it visible. Form an image. During the image forming operation, the print medium is supplied from the paper feed cassette to transfer the visible image, and then discharged to the outside of the image forming apparatus through a fixing process.

1 is a view showing a conventional color image forming apparatus.

The operation of the conventional image forming apparatus as described above will be described with reference to FIG. 1.

When a laser beam is irradiated on the photoconductor unit (not shown) to a plurality of photoconductors 11 charged at a constant potential, an electrostatic latent image is formed on the surface of the photoconductor 11. Then, when the developer supplied by the developing unit (not shown) adheres to the electrostatic latent image forming portion of the photosensitive member 11, a visible image is formed. The visible image is transferred to the transfer belt 13 while being pressed by a plurality of first transfer rollers 12 corresponding to each photosensitive member 11, and finally, the print medium P is finally printed by the second transfer roller 16. Is transferred). The print medium P on which the image image is transferred is discharged to the outside of the image forming apparatus after fixing. Here, the transfer belt 13 circulates in the same direction as the rotational direction of the photosensitive member 11, and a constant tension is applied to the driving roller 14 and the transfer belt 13 for driving the transfer belt 13 therein. The tension roller 15 is installed to support the transfer belt 13.

In such a print job, the transfer process is an important process that affects the quality of printing. Therefore, the image formed on the photosensitive member 11 must be moved to a desired point in sequence so that the transfer belt 13 does not have a shift in each color. Quality can be maintained. To this end, the transfer belt 13 should not have left and right flow in the traveling direction at constant speed, that is, the transfer belt should be stretched or flow should not occur in the transverse direction of the traveling direction. However, belts made of a flexible material have a problem of non-linear flow. Therefore, when the transfer belt 13 is extended, the traveling speed is not constant, in particular, there is a problem in that meandering occurs in the transverse direction with respect to the traveling direction.

When the transfer belt is thus stretched, the length of the transfer belt is variable. For this reason, the rotational speed of the transfer belt 13 is variable.

Therefore, there is a problem in that color implementation of a plurality of overlapping images is not accurately performed. That is, the visible images formed on the plurality of photoreceptors are superimposed on the transfer belt and the overlapping images are shifted from each other, resulting in a problem of poor image quality.

In addition, although a separate roller 17 is installed to maintain the tension of the transfer belt, it is difficult to cope with the height limitation, there is also a problem that a lot of restrictions on the installation space.

The present invention has been made to solve the above problems, and a first object of the present invention is to provide an intermediate transfer unit for a color image forming apparatus that can maintain a uniform rotation speed of the transfer belt.

A second object of the present invention is to provide an intermediate transfer unit for a color image forming apparatus which can maintain a constant tension of the transfer belt by correcting sagging of the transfer belt in real time.

A third object of the present invention is to provide an intermediate transfer unit for a color image forming apparatus which can prevent meandering of the transfer belt in the running direction.

A fourth object of the present invention is to provide an intermediate transfer unit for a color image forming apparatus which can improve the image quality of a superimposed image transferred by a transfer belt from a plurality of photosensitive members.

A fifth object of the present invention is to provide an intermediate transfer unit for a color image forming apparatus, which can be compactly solved by solving the height limitation of the installation space of the transfer unit.

In order to achieve the above object, the present invention provides an intermediate transfer unit of a color image forming apparatus.

The intermediate transfer unit includes a transfer belt having a belt surface, a driving roller for rotating the transfer belt, a plurality of pressure rollers providing pressure elasticity in different directions to the belt surface, and a belt surface of the transfer belt. A plurality of transfer rollers in contact with the pressure elastic force control unit for adjusting the pressure elastic force of the pressure rollers.

Here, each of the pressing rollers is preferably provided with a rotating shaft, a fixed frame connected to both ends of the rotating shaft for rotation support, and an elastic spring connected to the fixed frame to provide a pressing elastic force.

And, the direction of the pressing elastic force of the pressure rollers preferably form a direction perpendicular to each other.

In addition, it is preferable that the fixed frame in which the pressure roller generating the orthogonal pressing elastic force is rotatably supported flows integrally with a cleaning part for cleaning the outer surface of the transfer belt.

On the other hand, the pressure rollers are disposed on the side corresponding to the drive rollers and the tension roller to provide a first pressing elastic force along the first axis with the transfer belt, and along the second axis in the direction orthogonal to the first axis And a plurality of alignment rollers in contact with the belt surface of the transfer belt to provide a bi-pressing elastic force to the transfer belt.

Here, it is preferable that the second pressing elastic force has an elastic force smaller than the first pressing elastic force.

In addition, the alignment rollers may be disposed to intersect the outer circumferential driving surface and the inner circumferential driving surface of the transfer belt so as to be different from each other along the second axis.

On the other hand, the pressing elastic force adjusting unit is a sensor for measuring the distance value with the belt surface of the transfer belt, a control unit for receiving an electrical signal from the sensor and the preset error range of the reference distance value, and the measured distance value It is preferable to include the lifting means for determining whether or not included in the error range of the reference distance value, and if not included one or more of the pressing rollers to change the pressing position.

Hereinafter, an intermediate transfer unit of a color image forming apparatus according to an exemplary embodiment will be described with reference to the accompanying drawings.

Figure 2 is a perspective view showing an intermediate transfer unit for a color image forming apparatus of the present invention, Figure 3 is a side view schematically showing an intermediate transfer unit for a color image forming apparatus according to an embodiment of the present invention.

Referring to Figure 2, the intermediate transfer unit of the color image forming apparatus of the present invention is provided with a transfer belt 100 having a belt surface 110 is formed. An inner driving end of the transfer belt 100 is provided with a driving roller 200. The driving roller 200 is in contact with the inner surface of the transfer belt 100 to supply power to rotate the transfer belt 100.

The transfer belt 100 is provided with a plurality of pressing rollers 300 which are in contact with the inner driving surface 111 of the belt surface 110 and provide pressing elastic force in different directions to the transfer belt 100. .

The pressure rollers 300 are provided with one tension roller 310 and a plurality of alignment rollers 350.

Referring to FIG. 3, the tension roller 310 is circumscribed on the inner surface of the transfer belt 100 to correspond to the position of the driving roller 200. That is, the tension roller 310 and the driving roller 200 are disposed to face each other. The tension roller 310 has a first rotating shaft 311 is formed at both ends. Both sides of the tension roller 310 is provided with a first fixing frame 410 having a first rotating hole 411 is supported to rotate the first rotating shaft 311.

The first body frame 510 is provided to be spaced a predetermined distance from the first fixing frame 410 toward the driving roller 200 side. The first fixing frame 410 is further formed with a guide protrusion (not shown) to be fitted into a guide hole (not shown) formed along the X-axis direction of the first body frame 510.

A first elastic member 610 is interposed between the first fixing frame 410 and the first body frame 510. The first elastic member 610 generates a first compressive elastic force along the X axis direction.

Meanwhile, as shown in FIG. 4, the alignment rollers 350 are disposed at the same level inside the transfer belt 100. That is, it is disposed on the relaxation axis (A) of the transfer belt (100). The outer surfaces of the alignment rollers 350 are external to the inner driving surface 111 of the transfer belt 100. Each of the alignment rollers 350 is provided with a second rotation shaft 351 at both ends thereof. On both sides of each of the alignment rollers 350, a second fixing frame 420 having a second rotating hole 421 to which the second rotating shaft 351 is rotated is provided. The second body frame 520 is spaced apart from the second fixing frame 420 by a predetermined distance downward along the Y-axis direction. A second elastic member 620 is interposed between the lower end of the second fixing frame 420 and the second body frame 520. The second elastic member 620 generates a second compressive elastic force along the Y-axis direction.

In addition, each of the second body frames 520 on which the second elastic member 620 is supported is connected to the lifting means 710. An actuator may be adopted as the lifting means 710. The lifting shaft 711 of the lifting means 710 may follow a second axis, that is, a Y axis. In addition, guide frames 521 for guiding the flow direction of the second elastic member 620 are positioned at both sides of the elevating means 710. The guide frame 521 is mounted to the second body frame 520.

On the other hand, the intermediate transfer unit is provided with a plurality of transfer roller (800). The transfer rollers 800 are disposed on the other side of the alignment rollers 350. The outer surfaces of the alignment rollers 350 are positioned on the tension shaft B of the transfer belt 100 and are externally oriented to the inner driving surface 111.

On the other hand, one or a plurality of sensors 910 are located at a position spaced a predetermined distance from the inner driving surface 111 where the transfer rollers 800 are located. The sensor 910 is preferably located in the inner space of the transfer belt 100. The sensor 910 is a sensor that detects a distance value from the inner driving surface 111 in the tension axis B of the transfer belt 100. The detector may be any one of a distance sensor, an optical sensor, and an ultrasonic sensor capable of detecting a distance value. In addition, any sensor capable of detecting a distance value may be adopted.

The elevating means 700 and the sensor 910 are electrically connected to the controller 920. The controller 920 receives a distance value measured from the sensor 910 with the inner driving surface 111 in real time. The controller 920 presets an error range of the reference distance value. The controller 920 compares the measured distance value and the reference distance value with each other. The controller 920 determines that the transfer belt 100 is stretched when the measured distance value is out of an error range of the reference distance value.

The controller 920 may transmit a driving signal to the plurality of lifting means 700 at the same time, or may selectively transmit.

Next will be described the operation of the intermediate transfer unit according to an embodiment of the present invention through the configuration as described above.

2 and 3, the tension roller 310 is in a state in which the first rotating shaft 311 is rotatably supported by the first fixing frame 410. The first fixed frame 410 is provided with a first compressive elastic force generated along the first axis, that is, along the X axis by the first elastic member 610 supported by the first body frame 510. Accordingly, the first fixing frame 410 is moved along the guide hole formed in the first body frame 510. Therefore, a predetermined first tension is formed in the transfer belt 100 by the tension roller 310 in which the first pressing elastic force along the X axis is generated.

Accordingly, when the transfer belt 100 is out of the elastic modulus, the transfer belt 100 maintains a constant tension by the tension roller 310 to which the first pressing elastic force is applied, thereby transferring the transfer belt 100. It can easily correspond to the permanent deformation of.

Meanwhile, the second rotation shaft 351 of each of the plurality of alignment rollers 350 is rotated and supported by the second fixed frame 420. In addition, the outer surfaces of the alignment rollers 350 are circumscribed to the inner driving surface 111 of the transfer belt 100 at the same level. Each of the alignment rollers 350 is provided with a second compressive elastic force in the Y-axis direction by the second elastic member 620. Here, the elastic force of the second elastic member 620 is formed to be smaller than the elastic force of the first elastic member 610. That is, the spring adopted by the second elastic member 620 is a spring whose elastic modulus is smaller than the elastic modulus of the first elastic member 610.

Therefore, the plurality of alignment rollers 350 pushes the transfer belt 100 along the Y-axis direction. Therefore, a second pressing elastic force along the Y axis at a plurality of positions is provided on the relaxation axis (A) of the transfer belt 100, the second tension is formed on the tension axis (B) of the transfer belt (100).

That is, the transfer belt 100 is applied with a first compressive elastic force along the X axis and a second compressive elastic force at a plurality of positions along the Y axis, so that the press elastic force in different directions is applied. Therefore, a predetermined or more tensile force may be provided to the inner driving surface 111 at the tension axis B of the transfer belt 100 where the alignment rollers 350 are positioned.

In addition, the sensor 910 located in the inner space of the transfer belt 100 measures a distance value with the inner driving surface 111 in the tension axis B of the transfer belt 100 in real time. The measured distance value is transmitted to the controller 920. Here, the sensor 910 measures the distance values with the inner driving surface 111 at a plurality of locations and transmits them to the control unit 920, and the control unit 920 calculates average distance values with respect to the measurement distance values. It can also be used as a measurement distance value.

Subsequently, the controller 920 continuously drives the transfer belt 100 through the driving roller 200 when the measured distance value is included in an error range of a preset reference distance value. However, if the measured distance value is not included in the error range of the predetermined reference distance value, it is determined that the transfer belt 100 is increased. Accordingly, the controller 920 drives the lifting means 700 until the measurement distance value is within the error range. Accordingly, each of the lifting means 700 raises the second fixing frame 420 to a predetermined height along the Y axis until the measurement distance value is within the error range. That is, the alignment rollers 350 on the loosening axis A of the transfer belt 100 are raised to a predetermined height, and the inner driving surface 111 is positioned at a plurality of positions by the rising alignment rollers 350. Is provided with a second compressive modulus.

On the other hand, the control unit 920 may drive all the lifting means 700 as described above, or may select any one to drive only the selected lifting means 700. In addition, the controller 920 may select the lifting means 700 sequentially or in an irregular order.

Accordingly, the transfer belt 100 driven as described above is provided with the first pressing elasticity force in the X-axis direction and the second pressing elasticity force in a plurality of positions in the Y-axis direction, whereby the transfer roller 800 is positioned. The tension axis B of the belt 100 may have a constant tension in real time.

Accordingly, the rotational speed of the belt 100 on the tension shaft B of the transfer belt 100 can be kept constant. Therefore, since the transfer belt 100 is circumscribed with the plurality of transfer rollers 800 and rotates at a constant speed, color transfer of a plurality of overlapping images may be accurate.

In addition, when the outer surface of the alignment rollers 350 to form the same level so as to be in contact with the inner belt surface 111 of the transfer belt 100 as described above, and the loosening axis (A) of the transfer belt 100 and It is also possible to reduce the variable for the height between the tension axes (B).

In addition, as shown in FIG. 3, since the first fixing frame 410 of the tension roller 310 is connected to the cleaning unit 450 in one frame, the cleaning blade of the cleaning unit 450 may be 451 and the distance (L) between the outer surface of the transfer belt 100 can be kept constant. That is, even when the length of the transfer belt 100 in the X-axis direction is changed as the first fixing frame 410 is moved along the X-axis direction by the first elastic member 610, the gap L Can be kept constant.

In addition, it may correspond to the length change of the transfer belt 100 generated due to the warpage of the first rotation shaft 311 of the tension roller 310.

Accordingly, the cleaning efficiency by the cleaning blade 451 in which a predetermined distance (L) of foreign matters caught on the outer surface of the transfer belt 100 may be maintained constant.

As described above, referring to FIG. 4 again, the alignment belt is provided with the first pressing elastic force due to the tension roller 310 pressed in the X-axis direction and pressed in the plurality of Y-axis directions. As the second pressing force is simultaneously or selectively provided by the rollers 350, a constant tension is formed in the tension axis B of the transfer belt 100, and thus the rotational speed of the transfer belt 100 is increased. Explained to be constant.

Next, the intermediate transfer unit of the color image forming apparatus according to another embodiment of the present invention will be described with reference to FIG. 5.

As shown in FIG. 5, the placement of the tension roller 310 may be the same as that of the embodiment.

In particular, the configuration connected to the second rotary shaft 351 of the plurality of alignment rollers 350, the second pressing elastic force is applied along the Y axis may be the same as the above embodiment. However, in another embodiment of the present invention, the second pressing elastic force differs from each other so as to cross and contact the outer circumferential driving surface 112 and the inner circumferential driving surface 111 of the transfer belt 100 so as to be different from each other along the second axis. .

That is, as shown in Figure 5, when the alignment roller 350 is composed of four, a set of abutting the inner driving surface 111 corresponding to the relaxation axis (A) of the transfer belt 100 The first rollers 350 ′ provide the second pressing elastic force to the transfer belt 100 along the Y-axis upward direction ↑ by the second elastic member 620. In addition, another set of second alignment rollers 350 ″ in contact with the outer driving surface 112 of the transfer belt 100 are respectively positioned between the first alignment rollers 350 ′, The second elastic member 620 provides the second pressing elastic force to the transfer belt 100 along the Y-axis downward direction (↓).

Therefore, the second pressing elastic forces in the direction intersecting at different positions are provided to the belt surface 110 at the relaxation axis A of the transfer belt 100.

Accordingly, the transfer belt 100 is provided with a first pressing elastic force in the X-axis direction and second pressing elastic forces that cross at a plurality of positions in the Y-axis direction. Therefore, the second pressing elastic force is applied to the relaxation axis A of the transfer belt 100 in a zigzag form, so that the tension in the relaxation axis A of the belt 100 is in the longitudinal direction of the belt 100. Can be corrected sequentially. Because of this, the tension in the tension axis (B) of the transfer belt 100 can be formed constant. In addition, the rotational speed of the transfer belt 100 may also be formed constant.

In addition, the plurality of alignment rollers 350 as described above are respectively connected to the lifting means 700 as in the above embodiment. In addition, the configuration of the control unit 920 and the sensor 910 in the embodiment is the same.

However, since the alignment rollers 350 are positioned to correspond to each other with respect to the relaxation axis A of the transfer belt 100, the direction in which the lifting shaft 710 of the lifting means 700 operates. This is different from each other.

In addition to the operation of the control unit 920, the configuration of the tension roller 100 and the configuration of the cleaning unit 450 connected to the first fixing frame 410 of the tension roller 100 is the same as in the above embodiment Therefore, the operation according to this will also be omitted below.

As described above, the present invention has an effect of maintaining a constant tension of the transfer belt rotated by the driving roller by applying a predetermined elastic force to the tension roller inscribed in the rotating transfer belt.

In addition, by providing the elastic force in the direction orthogonal to the direction of the elastic force applied by the tension roller by using the alignment roller as the transfer belt, the tension of the transfer belt is assisted and the foreign matter between the belt and the rollers. This instantaneous change in rotational speed of the transfer belt can be prevented.

Therefore, the tension of the transfer belt is corrected in real time through the tension roller and the alignment rollers, thereby maintaining the rotation speed of the transfer belt at a constant level.

In addition, the present invention has the effect of preventing the meandering of the transfer belt in the running direction, thereby improving the image quality of the superimposed image transferred from the plurality of photosensitive members to the transfer belt.

In addition, it is also possible to maintain the tension of the transfer belt as described above as well as to solve the height limitation of the installation space of the transfer unit in a compact configuration.

Claims (8)

A transfer belt having a belt surface; A driving roller for rotating the transfer belt; A plurality of press rollers which provide press elasticity in different directions to the belt surface; A plurality of transfer rollers in contact with the belt surface of the transfer belt; And An intermediate transfer unit of a color image forming apparatus comprising a pressing elastic force adjusting unit for adjusting the pressing elastic force of the pressing rollers. The method of claim 1, Each of the pressing rollers has a rotating shaft, a fixed frame connected to both ends of the rotating shaft to support rotation, and an elastic spring connected to the fixed frame to provide a pressing elastic force. unit. The method of claim 1, And the direction of the pressing elastic force of the pressing rollers constitutes a direction orthogonal to each other. The method of claim 3, wherein And the fixed frame in which the pressure roller generating the orthogonal pressure elastic force is rotated and connected is integrally connected to a cleaning part for cleaning the outer surface of the transfer belt. The method of claim 1, The pressure rollers are disposed on a side corresponding to the driving rollers, the tension rollers providing a first pressing elastic force along a first axis with the transfer belt, and a second pressure along a second axis in a direction orthogonal to the first axis. And a plurality of alignment rollers in contact with the belt surface of the transfer belt so as to provide an elastic force to the transfer belt. The method of claim 5, The second pressing elastic force is an intermediate transfer unit, characterized in that it has an elastic force less than the first pressing elastic force. The method of claim 5, The alignment rollers are arranged in such a manner as to intersect the outer circumferential driving surface and the inner circumferential driving surface of the transfer belt so that the second pressing elastic force is different from each other along the second axis. . The method of claim 1, The pressing elastic force adjusting unit includes a sensor for measuring a distance value from the belt surface of the transfer belt, a control unit for receiving an electrical signal from the sensor, and setting an error range of a reference distance value, and the measured distance value is the reference value. It is determined whether or not included in the error range of the distance value, and if not included, the intermediate transfer of the color image forming apparatus, characterized in that it comprises lifting means for changing the pressing position by selecting one or more of the pressing rollers. unit.

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