JP2001337536A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in which a contact state between a cleaning means and an carrier belt is maintained to be nearly constant even though the carrier belt is contracted or elongated because of temperature change in the inside of a device. SOLUTION: This device is provided with a driving roller 215 and a driven roller 214 on which the carrier belt 216 is extended and rotated, a tension means 12 to adjust the tension of the carrier belt by abutting on the carrier belt, and a cleaning means 16 to clean the carrier belt. The cleaning means 16 is arranged between the driving roller 215 and the tension means 12, and the driven roller 214 to support the carrier belt 216 is supported by a main frame 18 through an auxiliary supporting member 14a whose coefficient of thermal expansion is large so that the contact state between the cleaning means 16 and the carrier belt 216 is maintained to be nearly constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt made of a resin or the like for supporting an image formed from a recording material such as toner, a recording paper onto which the recording material has been transferred, and cleaning the belt. The present invention relates to an image forming apparatus having a cleaning unit, and more particularly to an image forming apparatus having a temperature correction function for cleaning conditions for cleaning the belt.

[0002]

2. Description of the Related Art In recent years, in an image forming apparatus for forming a color image, in order to form an image at a high speed, a tandem system in which a plurality of image forming stations are arranged to face an intermediate transfer carrier and a recording material transfer carrier. Image forming apparatuses are being actively developed. In a tandem type image forming apparatus, since a plurality of image forming stations are arranged in the apparatus, the size of the apparatus tends to increase. In addition, the structure of the device becomes complicated, and maintenance and measures for troubles tend to be difficult.

Therefore, it is necessary to devise the arrangement of process units such as an image station to avoid an increase in the size and complexity of the apparatus. For this reason, a belt-shaped intermediate transfer member that carries a toner image in an overlapping manner and a carrier that carries a recording sheet onto which a toner image is transferred are used. As shown in FIG. 6, this belt-shaped carrier 302
(Hereinafter, referred to as a transfer belt 302) includes a plurality of rollers 3
It is installed with a certain tension maintained by the support 04 and the support. Further, the transfer belt 302 generally uses one of the rollers as a driving roller, and is driven to rotate by its rotation operation.

In the transfer belt 302, since a residual toner remains on the surface of the transfer belt 302 during image formation, a cleaning device 306 for cleaning the surface of the transfer belt 302 for each image formation is required. As the cleaning device 306, the cleaning blade 3
06a is generally in contact with the surface of the transfer belt 302 to remove residual toner.

[0005] The cleaning device 306 is provided to perform cleaning at a portion other than the portion where the transfer belt 302 is supported by the roller 304.
That is, the cleaning blade 306a is moved to the transfer belt 30 at a portion where the roller 304 is not provided on the back side of the transfer belt 302.
2 and cleaning is performed. The reason is that if cleaning is performed at a position where the transfer belt 302 is supported by the roller 304, the transfer belt 302 and the roller 3
04, the transfer belt 3
This is to prevent the formation of irregularities on the surface of the substrate No. 02.
If irregularities are formed on the surface of the transfer belt 302, a cleaning failure is caused, and as a result, a good image cannot be formed.

Further, since the transfer belt 302 is formed of resin or the like, it easily expands and contracts due to a change in temperature. Therefore, the transfer belt 302 is provided with a tension adjusting mechanism 308 for adjusting the tension of the transfer belt 302 itself. The tension adjusting mechanism 308 applies a load to the transfer belt 302 in a direction substantially perpendicular to the tension direction of the tension roller 308a by a tension spring 308b in order to absorb expansion and contraction of the transfer belt 302 due to a temperature change or the like. Is to load. In general, the cleaning device 306 and the tension adjusting mechanism 308
Image forming station (photosensitive drum 310,
The transfer roller 310a is disposed on the side opposite to the side on which the transfer roller 310a is disposed.

[0007]

However, the position of the transfer belt 302 is unstable in a portion where there is no belt support member such as a roller 304 on the back surface of the transfer belt 302. In particular, the position of the transfer belt 302 between the roller 304 and the tension roller 308a changes greatly when the expansion and contraction of the transfer belt 302 due to a temperature change is corrected by the tension roller 308b. There is a method of solving this problem by inserting a rotation supporting member fixed between the cleaning device 306 and the tension roller 308a. In this case, a strong roller member is used as the rotation supporting member and a bearing or the like is used. The transfer belt 302 must be supported, so that the number of expensive parts increases and the cost increases. In addition, the tension of the transfer belt 302 changes due to a change in the circumferential length of the transfer belt 302 due to a temperature change, and the cleaning blade 306 a The state of contact with the belt 302 also changes.

[0008] Roller 304 and tension roller 308a
When the cleaning device 306 is provided between the cleaning device 306 and the cleaning blade 306a,
Angle of Contact between Transfer Belt and Transfer Belt 302 (Cleaning Condition)
Will change. Cleaning blade 3
The state (cleaning condition) of bite 06a into the transfer belt 302 also changes. Specifically, in a high temperature state, the transfer belt 302 expands, so that the transfer belt 302 is spread outward, as indicated by the broken line in FIG. 7 (3), the contact angle θ between the cleaning blade 306a of the cleaning device 306 and the transfer belt 302 is 1 in a normal state.
It expands to 19 ° while it is 7 °.

In a low temperature state, the transfer belt 302 contracts, so that the transfer belt 302 contracts inward,
It becomes like the one-dot chain line in FIG. Along with this, as shown in FIG. 7B, the contact angle θ between the cleaning blade 306a of the cleaning device 306 and the transfer belt 302 is reduced to 14 °. As a result, the frictional resistance between the cleaning blade 306a and the transfer belt 302 changes, causing the cleaning blade 306a and the transfer belt 302 to vibrate. This vibration causes problems such as generation of abnormal sound and occurrence of cleaning failure.

The present invention has been made in view of such a problem, and an object of the present invention is to automatically correct the expansion and contraction of the transfer belt 302 due to a temperature change, and to make the roller 304 and the tension roller 308 a Another object of the present invention is to provide an image forming apparatus which does not cause the above-described problems such as generation of abnormal noise and poor cleaning even when a cleaning device 306 for the transfer belt 302 is installed between the two.

[0011]

In order to achieve the above object,
The image forming apparatus according to claim 1 of the present invention includes a carrier belt, a plurality of support members that stretch and rotate the carrier belt, and contact the carrier belt to reduce the tension of the carrier belt. A tensioning means for adjusting, and a cleaning means for cleaning the carrier belt, wherein at least one of the plurality of support members is a fixed support member having a fixed mounting position. Is disposed between the fixed support member and the tension means, wherein the plurality of supports for supporting the carrier belt so that the contact state between the cleaning means and the carrier belt is substantially constant. It is characterized in that the position interval of the support member is automatically corrected for a temperature change.

According to this configuration, even if the temperature changes, the contact state between the carrier belt and the cleaning member hardly changes, so that the optimally set cleaning state can be always maintained. Therefore, it is possible to prevent the occurrence of cleaning failure and the generation of abnormal noise due to a change in the contact state between the carrier belt and the cleaning member.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising:
2. The image forming apparatus according to claim 1, wherein the fixed support member is installed and fixed to a main frame, and at least one of the plurality of support members that is not a fixed support member is a movable support member. The support member is larger than the thermal expansion coefficient of the main frame, and further, through an auxiliary support member made of a material larger than the thermal expansion coefficient of the carrier belt, between the fixed support member and the movable support member. It is characterized by being installed on the main frame.

According to this configuration, for example, when the temperature rises, the carrier belt and the main frame expand, but the auxiliary support member supporting the moving support member expands further, and
The distance between the movable support member and the fixed support member is extended. As described above, for a carrier belt having a long circumference and a large amount of expansion and contraction with respect to a temperature change, expansion and contraction of the carrier belt can be corrected by the relatively short auxiliary support member.

According to a third aspect of the present invention, there is provided an image forming apparatus comprising:
The image forming apparatus according to claim 2, wherein the tension unit is inscribed in the carrier belt, and connects a fixed portion of the auxiliary support member to a main frame and an operation portion that supports the movable support member, It is characterized in that the direction of the position change of the tension means with respect to the temperature change is set to intersect. According to this configuration, the change in the adjustment position of the tension means can be canceled out by the change in the length of the auxiliary support member and the change in the circumferential length of the carrier belt due to the temperature change. Therefore, the contact state between the cleaning member and the carrier belt can be maintained in a good state.

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising:
The image forming apparatus according to claim 2, wherein
The auxiliary support member may be supported by a regulating member that regulates displacement in a direction intersecting a direction connecting the fixed portion and the action portion, for example, in a direction orthogonal to the direction between the fixed portion and the action portion. Features. According to this configuration,
It is possible to prevent the auxiliary support member from being bent, etc., and it is possible to reliably correct for a temperature change.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
5. The image forming apparatus according to claim 2, wherein a moving support member supported by the auxiliary support member on a periphery of the carrier belt, the carrier belt and a cleaning member. 6. It is characterized in that the tension means is arranged between the contact point and the contact point. According to this configuration, even if the auxiliary support member is displaced to correct for a temperature change, the position of the carrier belt at the contact point between the carrier belt and the cleaning member does not change. Therefore, the contact state between the cleaning member and the carrier belt can be kept constant.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising:
The image forming apparatus according to any one of claims 1 to 5, wherein the carrier belt is a transfer / transport belt that carries a recording member that records an image. According to this configuration, the belt surface is reliably cleaned, and the back surface of a recording member such as recording paper can be prevented from being stained.

According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising:
The image forming apparatus according to any one of claims 1 to 5, wherein the carrier belt is an intermediate transfer belt for laminating and carrying a toner image and transferring the toner image to a recording member. I do. According to this configuration, the untransferred toner remaining on the belt is reliably removed, and a good image can be formed without adversely affecting the next image formation.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a digital color copying machine as an image forming apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a front cross section of an embodiment of a digital color copying machine according to the present invention. In FIG. 1, a document table 111 and an operation panel are provided on the upper surface of the main body of the digital color copying machine 1, and an image reading unit 110 and an image forming unit 210 are provided inside the main body of the copying machine 1. The upper surface of the document table 111 is supported so as to be openable and closable with respect to the document table 111, and has a predetermined positional relationship with respect to the surface of the document table 111 and a duplex automatic document feeder (RADF).
tic Document Feeder) 112 is attached.

Further, the automatic two-sided automatic document feeder 112
First, the document is conveyed such that one surface of the document faces the image reading unit 110 at a predetermined position on the document table 111,
After the image reading for this one side is completed,
The original is inverted so that the other surface faces the image reading unit 110 at a predetermined position on the original
To be conveyed toward. Then, after the two-sided image reading for one document is completed, the double-sided automatic document feeder 112 discharges this document and performs a double-sided conveyance operation for the next document. The operation of conveying the document and reversing the front and back is controlled in relation to the operation of the entire copying machine.

The image reading section 110 is disposed below the document table 111 for reading an image of a document conveyed onto the document table 111 by the automatic duplex document feeder 112. The image reading unit 110 includes the platen 111
Scanning body 113 reciprocating in parallel along the lower surface of
114, an optical lens 115, and a photoelectric conversion element C
And a CD line sensor 116.

The original scanning members 113 and 114 are composed of a first scanning unit 113 and a second scanning unit 114. A first scanning unit 114 includes an exposure lamp 113a for exposing the surface of the original image, and a first mirror 113 for deflecting a reflected light image from the original in a predetermined direction.
b, and reciprocates in parallel at a predetermined scanning speed while maintaining a fixed distance from the lower surface of the document table 111. The second scanning unit 114 has second and third mirrors 114a and 114b for further deflecting the reflected light image from the document deflected by the first mirror of the first scanning unit 113 in a predetermined direction. Then, the scanner reciprocates in parallel with the document table 111 while maintaining a constant speed relationship with the first scanning unit 113.

The optical lens 115 reduces the reflected light image from the document deflected by the third mirror 114b of the second scanning unit 114, and forms the reduced light image at a predetermined position on the CCD line sensor 116. It is to let. In the present embodiment, the optical lens 115 reduces the document width on the document table 111 at a predetermined magnification, and
6 is formed.

The CCD line sensor 116 photoelectrically converts the formed light image in order and outputs it as an electric signal. The CCD line sensor 116 reads a black-and-white image or a color image, and outputs R (red), G (green), and B (blue).
This is a three-line color CCD capable of outputting line data color-separated into each color component. The document image information converted into an electric signal by the CCD line sensor 116 is further transferred to an image processing unit (not shown) and subjected to predetermined image data processing. Note that the CCD line sensor 116 may be a one-line monochrome CCD.

Next, the configuration of the image forming unit 210 and the configuration of each unit related to the image forming unit 210 will be described.
Below the image forming unit 210, there is provided a paper feed mechanism 211 that separates sheets (recording media) P stacked and accommodated in a sheet tray one by one and supplies the separated sheets to the image forming unit 210. The paper P separated and supplied one by one is
The timing is controlled by a pair of registration rollers 212 disposed in front of the image forming unit 210 and the image forming unit 2
It is transported to 10. Further, the sheet P on which an image is formed on one side is re-supplied and conveyed to the image forming unit 210 in synchronization with the image formation of the image forming unit 210.

Below the image forming section 210, a transfer / transport belt mechanism 213 is disposed. The transfer conveyance belt mechanism 213 includes a driving roller (support member, fixed support member) 21.
The paper P is electrostatically attracted to a transfer / transport belt 216, which is a carrier belt stretched so as to extend substantially parallel between the transfer roller 5 and a driven roller (support member, movable support member) 214, and is transported. Has become.

Further, a fixing device 217 for fixing the toner image transferred and formed on the sheet P to the sheet P downstream of the transfer / conveyance belt mechanism 213 in the sheet conveyance path.
Is arranged. The sheet P that has passed through the nip between the pair of fixing rollers of the fixing device 217 passes through a conveyance direction switching gate 218 and is discharged by a discharge roller 219 to a discharge tray 2 attached to an outer wall of the copying machine main body 1.
20 is discharged.

The switching gate 218 is connected to the sheet P after fixing.
Is selectively switched between a path for discharging the sheet P from the copying machine main body 1 and a path for re-supplying the sheet P to the image forming unit 210. The sheet P whose transport direction has been switched again toward the image forming unit 210 by the switching gate 218 is turned upside down via the switchback transport path 221, and then the image forming unit 210 is turned over.
Is supplied again.

Above the transfer belt 216 in the image forming section 210, a first image forming station Pa, a second image forming station Pb, and a third image forming station are disposed adjacent to the transfer belt 216. P
c and a fourth image forming station Pd are arranged in order from the upstream side of the sheet transport path. The transfer conveyance belt 216 is frictionally driven by the drive roller 215 in the direction indicated by the arrow Z in FIG. 1, grips the sheet P fed through the sheet feeding mechanism 211 as described above, and transfers the sheet P to the image forming stations Pa to. Conveyed sequentially to Pd.

Since each of the image stations Pa to Pd has substantially the same configuration, one of them will be described in detail. Each image station Pa, Pb, Pc, Pd
Include photoconductor drums 222 that are driven to rotate in the direction of arrow F shown in FIG. Each photosensitive drum 222
A charger 223 for uniformly charging the photosensitive drum 222, a developing device 224 for developing the electrostatic latent image formed on the photosensitive drum 222, and a developed photosensitive drum 222 A transfer discharger 225 for transferring the upper toner image onto the sheet P and a cleaning device 226 for removing the toner remaining on the photosensitive drum 222 are sequentially arranged along the rotation direction of the photosensitive drum 222.

Further, above each photosensitive drum 222,
Laser beam scanner units 227a, 227b,
227c and 227d are provided respectively. Since the laser beam scanner units 227a to 227d have the same configuration, one of them will be described in detail. The laser beam scanner unit 227a includes a semiconductor laser device (not shown) that emits dot light modulated according to image data, and a polygon mirror (deflecting device) for deflecting a laser beam from the semiconductor laser device in the main scanning direction.
240, and an fθ lens 241 and mirrors 242 and 243 for forming an image of the laser beam deflected by the polygon mirror 240 on the surface of the photosensitive drum 222.

The laser beam scanner 227a receives a pixel signal corresponding to a black component image of a color original image, the laser beam scanner 227b receives a pixel signal corresponding to a cyan component image of a color original image, and the laser beam scanner 227c. The pixel signal corresponding to the magenta color component image of the color original image is output to the laser beam scanner 2
A pixel signal corresponding to the yellow component image of the color document image is input to 27d.

As a result, an electrostatic latent image corresponding to the color-converted document image information is formed on each photosensitive drum 222 of each of the image stations Pa to Pd. The developing device 224 of the image station Pa has black toner, the developing device 224 of the image station Pb has cyan toner, the developing device 224 of the image station Pc has magenta toner, and the image station Pd has The developing device 224 contains yellow toner, and the electrostatic latent image on each photoconductor drum 222 is developed with the toner of each color. Thereby, the image forming unit 2
The document image information color-converted at 10 is reproduced as a toner image of each color.

The paper P supplied from the paper feeding mechanism 211 is
The sheet is conveyed without shifting between the first image forming station Pa and the fourth image forming station Pd while being attracted onto the transfer conveying belt 216. The driving roller 21 is disposed between the fourth image station Pd and the fixing device 217.
Almost immediately above 5, a static eliminator 229 is provided. An alternating current is applied to the neutralizer 229 to separate the paper P electrostatically attracted to the transport belt 216 from the transfer transport belt 216.

In the digital color copying machine 1 having the above configuration, cut sheet-shaped paper is used as the paper P.
When the sheet P is sent out of the sheet cassette and supplied to the guide of the sheet feeding path of the sheet feeding mechanism 211, the leading end of the sheet P is detected by a sensor (not shown). Is temporarily stopped by the pair of registration rollers 212 based on the detection signal output from the pair. Then, the paper P is sent onto the transfer / conveying belt 216 rotating in the direction of arrow Z in FIG. 1 at the timing of each of the image stations Pa to Pd.
Is transported and supplied.

In each of the image stations Pa to Pd, a toner image of each color is formed, and is superposed on the display surface of the paper P conveyed by being electrostatically attracted by the transfer / conveyance belt 216. Fourth image station Pd
When the transfer of the image by the printer P is completed, the sheet P is sequentially transferred from the leading end portion thereof by the charge removing device 229 to the transfer conveyance belt 216.
It is peeled off from above and guided to the fixing device 217. Finally, the paper P on which the toner image has been fixed is discharged onto a paper discharge tray 220 from a paper discharge port (not shown).

In the above description, the laser beam is scanned and exposed by the laser beam scanner units 227a to 227d to write light on the photosensitive drum. However, a writing optical system (LED head) including a light emitting diode array and an imaging lens array may be used instead of the laser beam scanner unit. The LED head is smaller in size than the laser beam scanner unit, and has no moving parts and is silent. Therefore, it can be suitably used in an image forming apparatus such as a tandem type digital color copying machine which requires a plurality of optical writing units.

FIG. 2 is a schematic front sectional view showing the structure of a digital color copying machine 2 which is another image forming apparatus according to the embodiment of the present invention. Components having the same configuration and function as those of the digital color copying machine 1 described in FIG.
The description is omitted.

This digital color copying machine 2 has a transfer and conveyance belt 216 in the digital color copying machine 1 shown in FIG.
Instead of the intermediate transfer belt 216 as a carrier belt
'Is provided. The digital color copying machine 1 is for directly transferring the toner images of each color formed in each of the image stations Pa to Pd onto the sheet P adsorbed on the transfer conveyance belt 216. On the other hand, in the digital color copying machine 2, each of the image stations Pa to P
The toner images of the respective colors formed by d are temporarily superimposed and transferred onto the intermediate transfer belt 216 '. And
The toner images of the respective colors stacked on the intermediate transfer belt 216 ′ are simultaneously transferred onto the sheet P.

Next, the configuration around the transfer / transport belt 216 in the digital color copying machine 1 of FIG. 1 and the intermediate transfer belt 216 'in the digital color copying machine 2 of FIG. 2 will be described in detail with reference to FIGS. explain. Note that the configuration described below is substantially the same for the transfer conveyance belt 216 and the intermediate transfer belt 216 ′ as the carrier belts.
Only 6 will be described. 3 to 5, some of the components shown in FIGS. 1 and 2 are omitted.

As shown in FIG. 3, the transfer conveyance belt 216
Is stretched around the driven roller 214 and the driving roller 215. The driven roller 214 and the driving roller 21
Reference numeral 5 is attached to a main frame 18 fixed to the main body of the digital color copying machine 1. The drive roller 215 is a fixed support member whose rotation axis is fixed to the main frame 18. The drive roller 215 rotates the transfer conveyance belt 216 by being rotated by a drive system (not shown). On the other hand, the driven roller 214
Is a moving support member whose rotation axis is supported so as to be movable in the horizontal direction with respect to the main frame 18 via a stretching position adjusting mechanism 14 described later.

The transfer conveyance belt 216 is provided with a tension adjusting mechanism (tension means) 12 and a tension position adjusting mechanism 14 (see FIG. 4 described later). The tension adjusting mechanism 12 is provided inside the transfer conveyance belt 216 on the side opposite to the side where the photosensitive drums 222 a to 222 d are installed with respect to the transfer conveyance belt 216. The stretch position adjusting mechanism 14 is provided for the driven roller 214 that stretches the transfer / transport belt 216, and moves the driven roller 214 in the direction in which the transfer / transport belt 216 is stretched (horizontal direction). Is to be displaced.

On the outer periphery of the transfer / conveying belt 216,
A cleaning unit (cleaning means) 16 is provided. The cleaning unit 16 is provided outside the transfer conveyance belt 216 on the opposite side of the transfer conveyance belt 216 from the side where the photosensitive drum 222 is installed.

The tension adjusting mechanism 12, the cleaning unit 16 and the stretch position adjusting mechanism 14 will be described in more detail. The tension adjusting mechanism 12 includes a tension roller 12a, a tension roller support plate 12b, a tension spring 12c, and a guide pin 12d. The tension roller 12a is rotatably supported by a rotation shaft fixed to the tension roller support plate 12b via a bearing. The tension roller 12a is in contact with the inside of the transfer conveyance belt 216.

The tension roller support plate 12b is fitted in a long hole provided in the tension roller support plate 12b, and is substantially in the direction in which the transfer conveyance belt 216 is stretched by guide pins 12d fixed to the main frame 18. It is provided movably in the vertical direction. The tension roller support plate 12b supports the other end of the tension spring 12c whose one end is supported by the main frame 18.

As a result, the transfer conveyance belt 216
A substantially constant load in the outward direction is always applied via the tension roller 12a. Then, the transfer conveyance belt 216
Has a substantially constant tension. That is, the transfer conveyance belt 216 is stretched until the tension of the transfer conveyance belt 216 and the force of the tension spring 12c are balanced. Here, two tension rollers 12a are provided, and the tension rollers 12a are set so that the load of the tension spring 12c acts at a substantially intermediate position between the tension rollers 12a.

The cleaning unit 16 comprises a cleaning blade (cleaning member) 16a and a cleaning blade holder 16b. The cleaning blade holder 16b is mounted on the main frame 1
8 and is fixed at a predetermined position, and supports the cleaning blade 16a. Then, the cleaning blade 16 a contacts the transfer conveyance belt 216, so that the toner remaining on the transfer conveyance belt 216 can be removed. Here, the cleaning blade 1
6a and the transfer conveyance belt 216 make an angle of about 17 °.
It is set to be.

The position at which the cleaning blade 16a contacts the transfer / transport belt 216 (hereinafter referred to as the cleaning position) is the position at which the tension roller 12a contacts the transfer / transport belt 216, and the position at which the drive roller 215 contacts the transfer / transport belt. 216. That is, the cleaning position is set at a position opposite to the tension position adjusting mechanism 14 with respect to the tension roller 12a.

Thus, a stretching position adjusting mechanism 1 to be described later
4, the position of the driven roller 214 is displaced.
The above-described angle between the cleaning blade 16a and the transfer conveyance belt 216 can be kept substantially constant. Then, the cleaning conditions can be maintained in an optimal state. In particular, it is preferable that the cleaning position is near the drive roller 215 within the above range. Thereby, at the contact position between the cleaning blade 16a and the transfer conveyance belt 216, the transfer conveyance belt 216
In this case, the effect of vibration can be reduced, the contact state can be stabilized, and cleaning can be performed stably.

The tension position adjusting mechanism 14 will be further described with reference to FIGS. As shown in FIG. 4, the tension position adjusting mechanism 14 includes an auxiliary support member 14a, a fixing screw 14b, and a stepped screw (restriction member) 14c. The auxiliary support member 14a is formed from a member having a large thermal expansion coefficient. This auxiliary support member 14
As a material forming a, a material having a thermal expansion coefficient larger than the thermal expansion coefficient of the main frame 18 and the thermal expansion coefficient of the transfer conveyance belt 216 is used. As this material,
Specifically, polyacetal and nylon are preferred. By integrally molding a member made of such a material, a member having a predetermined length in the longitudinal direction is formed.

One end of the auxiliary support member 14a in the longitudinal direction is fixed to the main frame 18 between the fixed roller 215 and the driven roller 214 by a fixing screw 14b. The other end supports the rotation shaft of the driven roller 214. Then, the fixing position A (hereinafter, referred to as a fixing position A) by the fixing
A range C (hereinafter, referred to as a fixed portion) and a supporting position B (hereinafter, referred to as an action portion) of the rotating shaft of the driven roller 214.
In the expansion and contraction range, the auxiliary support member 14a expands and contracts in response to a change in temperature, so that the transfer conveyance belt 21
6 can be displaced in the stretched position by the driven roller 214.

The fixed portion A is located on the driving roller 215 side with respect to the position where the driven roller 214 supports the rotating shaft. As a result, when the temperature rises and the transfer conveyance belt 216 extends, the distance between the driven roller 214 and the drive roller 215 increases. Also, when the transfer conveyance belt 216 contracts due to a decrease in temperature, the distance between the driven roller 214 and the drive roller 215 decreases.

The auxiliary support member 14a is formed with a long hole whose longitudinal direction is set in the expansion and contraction direction in the expansion and contraction range C. The movable support portion D is formed by fitting a stepped screw 14c (a regulating member) fixed to the main frame 18 into the elongated hole. This supports the load (in particular, the gravity applied to the driven roller 214) in the direction perpendicular to the longitudinal direction of the auxiliary support member 14a.

Further, since the auxiliary support member 14a is manufactured by resin molding, its sectional shape is shown in FIGS. 5 (1) to 5 (5) in order to improve the load resistance in the vertical direction with respect to the longitudinal direction and to prevent bending. It is formed in a shape as shown in (3). In the resin molding, it is necessary to make the wall thickness uniform, and preferably the cross-sectional shape shown in FIGS. Here, in order to adjust the tension position of the transfer conveyance belt 216, the driven roller 214
Utilizing the thermal expansion of the auxiliary support member 14a for supporting
The position of the driven roller 214 may be controlled by an actuator capable of electronic control.

[0056]

An embodiment of the present invention will be described. Here, the cleaning blade 16a of the cleaning unit 16 uses urethane rubber having a thickness of 2 mm and a width of 320 mm. Then, the cleaning blade 16a
In a state of protruding about 10 mm from the cleaning blade holder 16b, it is fixed so as to come into contact with the transfer conveyance belt 216 at an angle of 17 ° (FIG. 7).
(See (1)).

The allowable range of the angle (cleaning angle) between the transfer belt 216 and the cleaning blade 16a is 17 ° ± 1 °, and within this range, the cleaning performance is good. The transfer conveyance belt 216 used had a circumference of 860 mm. As a material of the transfer conveyance belt 216, polyimide (PI), polycarbonate (PC), polyvinylidene fluoride (P
VDF), an ethylene-tetrafluoroethylene polymer (E
TFE) is common. These materials have a thermal expansion coefficient (linear expansion coefficient) of 5 to 8 × 10 ⁻⁵ (/ K). Here, the transfer conveyance belt 216 was formed of polyimide having a thickness of 100 μm. In the case of polyimide, the coefficient of thermal expansion (linear expansion coefficient) is 5.8 × 10 ⁻⁵ (/ K).

Here, the use environment of the digital color copying machine 1 is usually 5 to 35 ° C., but a temperature difference of about 40 ° C. occurs because the temperature in the apparatus is higher than the ambient temperature. Therefore, when the temperature change is 40 ° C., the transfer conveyance belt 216 expands and contracts by about 2 mm in the circumferential direction. Considering that the transfer conveyance belt 216 is folded back and stretched, when the temperature change is 40 ° C.,
The transfer conveyance belt 216 expands and contracts by 1 mm in the stretching direction.

The auxiliary support member 14a was formed of polyacetal or nylon having a coefficient of thermal expansion of 10 × 10 ⁻⁵ (/ K). Then, the extension and contraction range C of the auxiliary support member 14a (the fixed position by the fixing screw 14b and the driven roller 2)
The range between the positions of the 14 rotating shafts and the supporting positions) was set to 250 mm. As a result, a temperature change of 40 ° C.
mm. That is, the position of the driven roller 214 can be corrected by 1 mm.

Thus, the expansion and contraction of the transfer support belt 216 can be absorbed by the expansion and contraction of the auxiliary support member 14a. Although the thermal expansion of the main frame 18 and the like is not considered here, it is not necessary to consider this thermal expansion because it is sufficiently smaller than the thermal expansion of the transfer conveyance belt 216 and the auxiliary support member 14a.

With this configuration, when a temperature change of 40 ° C. was given to actually perform the image forming operation, the change in the cleaning angle (cleaning condition) between the transfer / conveyance belt 216 and the cleaning blade 16a was set within the allowable range (1).
7 ° ± 1 °). Then, it was confirmed that the transfer conveyance belt 216 was well cleaned, and a sheet on which a good image without residual toner was formed was formed.

[0062]

As can be understood from the above description, in the image forming apparatus of the present invention, the contact state between the carrier belt and the cleaning member hardly changes even if the temperature changes. The cleaning state can be always maintained, and the occurrence of cleaning failure and the generation of abnormal noise due to the change in the contact state between the carrier belt and the cleaning member can be prevented.

Further, when the auxiliary support member expands and contracts further with respect to the expansion and contraction of the carrier belt, the expansion and contraction of the carrier belt can be absorbed and corrected. If the direction connecting the fixing portion of the auxiliary support member to the main frame and the operation portion supporting the support member is set to intersect with the direction of the position change of the tension means with respect to the temperature change, the adjustment position of the tension means changes. Can be canceled, and the contact state between the cleaning member and the carrier belt can be maintained in a good state.

If the auxiliary support member is supported between the fixed portion and the operating portion by a restricting member that restricts displacement in a direction intersecting the direction connecting the fixed portion and the active portion, bending of the auxiliary support member can be prevented. Therefore, it is possible to surely correct the temperature change. On the circumference of the carrier belt, if tension means is disposed between the moving support member supported by the auxiliary support member and the contact point between the carrier belt and the cleaning member, the cleaning member and the carrier belt can be separated. The contact state can be kept constant.

When the carrier belt is used as a transfer / conveying belt for carrying a recording member for recording an image, the belt surface is reliably cleaned, and the back surface of the recording member such as recording paper can be prevented from being stained. In addition, if the carrier belt is used as an intermediate transfer belt for laminating and carrying a toner image and transferring the toner image to a recording member, untransferred toner remaining on the belt is surely removed, and is used for the next image formation. Without any adverse effects,
A good image can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a front cross section of a digital color copier including an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing a front cross-section of an example of another digital color copying machine including the image forming apparatus according to the present invention.

FIG. 3 is a main configuration diagram showing a transfer conveyance belt mechanism and a cleaning unit.

FIG. 4 is an essential part perspective view showing a relationship between an auxiliary support member and a movable support member.

FIG. 5A is a cross-sectional view of the auxiliary support member of FIG.
(2), (3) is sectional drawing of each other auxiliary support member.

FIG. 6 is a main configuration diagram showing a conventional transfer conveyance belt mechanism and a cleaning unit.

FIGS. 7A and 7B are operation explanatory diagrams showing a positional relationship between a cleaning unit and a transfer belt, wherein FIG. 7A shows a normal temperature state, FIG. 7B shows a low temperature state, and FIG.

[Explanation of symbols]

 Reference numerals 1 and 2 Digital color copier 12 Tension adjusting mechanism (tension means) 14 Tension position adjusting mechanism 14a Auxiliary support member 14c Stepped screw (restriction member) 16 Cleaning unit (cleaning means) 18 Main frame 214 Follower roller (moving support member) 215 Drive Roller (Fixed Support Member) 216 Transfer Conveying Belt (Carrier Belt) 216 ′ Intermediate Transfer Belt (Carrier Belt) 222 Photoconductor Drum A Fixed Part B Working Part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Nakayama 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Corporation (72) Inventor Koichi Nakamura 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Incorporated (72) Inventor Fumio Shimadzu 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H032 AA05 BA18 BA30 CA02 CA14

Claims (7)

[Claims] A carrier belt; a plurality of support members for stretching and rotating the carrier belt; tension means for abutting on the carrier belt to adjust the tension of the carrier belt; Cleaning means for cleaning a body belt, wherein at least one of the plurality of support members is a fixed support member having a fixed mounting position, and the cleaning means includes the fixed support member and a tension means. Wherein the distance between the plurality of support members supporting the carrier belt is set to a temperature such that the contact state between the cleaning unit and the carrier belt is substantially constant. An image forming apparatus, wherein correction is performed in response to a change. 2. The fixed support member is mounted and fixed to a main frame, and at least one of the plurality of support members that is not a fixed support member is a movable support member,
The movable support member is provided between the fixed support member and the movable support member via an auxiliary support member made of a material having a larger thermal expansion coefficient than the main frame and further having a larger thermal expansion coefficient than the carrier belt. The image forming apparatus according to claim 1, wherein the image forming apparatus is supported by the main frame. 3. A direction in which the tension means is inscribed in the carrier belt and connects a portion where the auxiliary support member is fixed to the main frame and an operation portion which supports the movable support member, and a position of the tension member with respect to a temperature change. 3. The image forming apparatus according to claim 2, wherein the directions of the fluctuations are set to intersect. 4. The auxiliary support member is supported by a regulating member that regulates a displacement between the fixed part and the action part in a direction intersecting a direction connecting the fixed part and the action part. The image forming apparatus according to claim 2, wherein: 5. The tension means is arranged on a periphery of the carrier belt between a moving support member supported by the auxiliary support member and a contact point between the carrier belt and a cleaning member. The image forming apparatus according to any one of claims 2 to 4, wherein: 6. The image forming apparatus according to claim 1, wherein the carrier belt is a transfer / transport belt that carries a recording member for recording an image. 7. The image forming apparatus according to claim 1, wherein the carrier belt is an intermediate transfer belt for laminating and carrying a toner image and transferring the toner image to a recording member.
Item 10. The image forming apparatus according to item 1.