Patent Application
20140119782
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2012-239088 filed on Oct. 30, 2012, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an image forming apparatus capable of forming a monochrome image in a single color and a color image composed of a plurality of colors.
An image forming apparatus such as a color printer includes, for example, a plurality of photosensitive drums that allow toner images for respective colors of black, yellow, magenta, and cyan to be formed thereon, and an intermediate transfer belt onto which the toner images formed on the plurality of photosensitive drums are to be transferred. The toner images for respective colors formed on the photosensitive drums are primarily transferred onto the intermediate transfer belt, and then collectively secondarily transferred onto a paper sheet from the intermediate transfer belt. Thus, a color image is formed on a paper sheet.
The above-described intermediate transfer belt extends over a drive roller linked with a drive source such as a motor, and a plurality of driven rollers. The intermediate transfer belt is rotated (endlessly moved) along with rotation of the drive roller, whereby toner images are sequentially transferred at positions opposing to the respective photosensitive drums.
The intermediate transfer belt may meander to deviate in the width direction of a roller during rotation. If the intermediate transfer belt meanders during rotation, when toner images are primarily transferred onto the intermediate transfer belt from the respective photosensitive drums, the positions of the toner images are displaced from each other, and this may cause color shift.
Conventionally, an image forming apparatus is known which includes a meandering resolving mode in which the orientation of a driven roller is set to a meandering resolving position so that the meandering intermediate transfer belt will return to a target position (reference position or such a range), and an equilibrium retaining mode in which the orientation of the driven roller is set to an equilibrium position so that the intermediate transfer belt will be retained at the target position. The image forming apparatus can return the meandering intermediate transfer belt to a target position by executing the meandering resolving mode.
The intermediate transfer belt may abnormally meander due to assembly defect of a drive mechanism such as a drive roller, for example. In the case where the intermediate transfer belt abnormally meanders, it may be impossible to return the intermediate transfer belt to a target position even if the image forming apparatus is operated in the above meandering resolving mode. In this case, printing by the image forming apparatus is automatically stopped. Then, until the defect is repaired, the image forming apparatus cannot perform either color printing and monochrome printing.
An image forming apparatus according to one aspect of the present disclosure includes a first image carrier, a plurality of second image carriers, a transfer belt of endless belt type, a drive roller, a driven roller, a first opposing portion, a plurality of second opposing portions, a movement mechanism portion, position information acquiring portion, a first control portion, and a second control portion. A toner image is to be formed on the first image carrier. Toner images are to be formed on the plurality of second image carriers. The toner images formed on the first image carrier and/or the second image carriers are to be transferred onto the transfer belt of endless belt type. The drive roller supports the transfer belt in a rotatable manner and is capable of rotating the transfer belt. The driven roller supports the transfer belt in a rotatable manner. The first opposing portion is provided opposing to the first image carrier via the transfer belt and causes the transfer belt to contact the first image carrier. The plurality of second opposing portions are provided opposing to the plurality of second image carriers via the transfer belt and are each capable of being positioned at either contact positions that cause the transfer belt to contact the plurality of second image carriers or separation positions that cause the transfer belt to be separated from the plurality of second image carriers. The movement mechanism portion moves the positions of the plurality of second opposing portions to the contact positions or the separation positions. The position information acquiring portion acquires position information with respect to a width direction about the transfer belt. The roller position adjustment mechanism adjusts the orientation of a rotary shaft of the driven roller. The first control portion determines correction information for returning the transfer belt to a predetermined target position, based on the position information about the transfer belt acquired by the position information acquiring portion, and controls the roller position adjustment mechanism based on the correction information. The second control portion, in the case where, during the control for the roller position adjustment mechanism based on the correction information by the first control portion, the transfer belt does not return into a correction range centered on the target position within a predetermined time and is out of the correction range, controls the movement mechanism portion so as to change the positions of the plurality of second opposing portions.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description with reference where appropriate to the accompanying drawings. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.
Hereinafter, an embodiment in the case where an image forming apparatus according to the present disclosure is applied to a printer capable of four-full-color printing and monochrome printing will be described with respect to the drawings.
With reference to
As shown in
As shown in
As shown in
In addition, as shown in
Next, each component will be described in the order, the image forming portion 30, the sheet feed/discharge portion 40, and then the belt device 20.
First, the image forming portion 30 will be described. In the image forming portion 30, electric charging by the charging portions 10a, 10b, 10c, and 10d, light exposure by the laser scanner units 4a, 4b, 4c, and 4d, development by the developing devices 16a, 16b, 16c, and 16d, primary transfer by an intermediate transfer belt 7 (hereinafter, may be referred to as a “belt” with no reference character) and the primary transfer rollers 13a, 13b, 13c, and 13d, electricity removal by the electricity removing devices 12a, 12b, 12c, and 12d, and cleaning by the drum cleaning portions 11a, 11b, 11c, and 11d, are performed sequentially from upstream to downstream (left to right in
In addition, in the image forming portion 30, secondary transfer by the intermediate transfer belt 7, a secondary transfer roller 8, and the drive roller 17, and fixing by the fixing portion 60, are performed.
The photosensitive drums 2a, 2b, 2c, and 2d are image carriers formed by cylindrical members. In the present embodiment, the photosensitive drum 2a is a second image carrier on which a toner image for yellow (Y) is to be formed, the photosensitive drum 2b is a second image carrier on which a toner image for cyan (C) is to be formed, the photosensitive drum 2c is a second image carrier on which a toner image for magenta (M) is to be formed, and the photosensitive drum 2d is a first image carrier on which a toner image for black (B) is to be formed.
Upon formation of a color image, toner images for the respective colors are formed on the photosensitive drums 2a, 2b, 2c, and 2d. On the other hand, upon formation of a monochrome image, a toner image for black is formed on the photosensitive drum 2d while toner images are not formed on the other photosensitive drums 2a, 2b, and 2c.
The photosensitive drums 2a, 2b, 2c, and 2d are provided so as to be rotatable in directions indicated by arrows around an axis extending in a direction perpendicular to the movement direction of the intermediate transfer belt 7. Electrostatic latent images are to be formed on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.
The charging portions 10a, 10b, 10c, and 10d are provided facing to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The charging portions 10a, 10b, 10c, and 10d each uniformly charge the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d into negative (minus polarity) or positive (plus polarity).
The laser scanner units 4a, 4b, 4c, and 4d function as light exposure units. The laser scanner units 4a, 4b, 4c, and 4d are provided being spaced from the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The laser scanner units 4a, 4b, 4c, and 4d each include a laser light source, a polygon mirror, a motor for driving the polygon mirror, and the like (with no reference characters) not shown.
The laser scanner units 4a, 4b, 4c, and 4d scan and expose, to light, the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d based on image information inputted from an external apparatus such as a PC (personal computer). Electric charges on portions of the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d that have been scanned and exposed to light are removed. Thus, electrostatic latent images are formed on the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d.
The developing devices 16a, 16b, 16c, and 16d are provided being associated with the respective photosensitive drums 2a, 2b, 2c, and 2d and facing to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The developing devices 16a, 16b, 16c, and 16d apply toners for respective colors to electrostatic latent images formed on the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d, whereby toner images for respective colors are formed on the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The developing devices 16a, 16b, 16c, and 16d respectively correspond to four colors of yellow, cyan, magenta, and black. The developing devices 16a, 16b, 16c, and 16d include development rollers facing to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d, stirring rollers for stirring toners, and the like (with no reference characters).
The toner cartridges 5a, 5b, 5c, and 5d are provided being associated with the respective developing devices 16a, 16b, 16c, and 16d, and contain toners for respective colors to be fed to the respective developing devices 16a, 16b, 16c, and 16d. The toner cartridges 5a, 5b, 5c, and 5d contain a toner for yellow, a toner for cyan, a toner for magenta, and a toner for black, respectively.
The toner feed portions 6a, 6b, 6c, and 6d are provided being associated with the respective toner cartridges 5a, 5b, 5c, and 5d and the respective developing devices 16a, 16b, 16c, and 16d. The toner feed portions 6a, 6b, 6c, and 6d feed toners for respective colors contained in the respective toner cartridges 5a, 5b, 5c, and 5d to the respective developing devices 16a, 16b, 16c, and 16d. The toner feed portions 6a, 6b, 6c, and 6d are connected to the respective developing devices 16a, 16b, 16c, and 16d via toner feed paths not shown.
On a side of the intermediate transfer belt 7 opposite to the photosensitive drums 2a, 2b, 2c, and 2d, the primary transfer rollers 13a, 13b, 13c, and 13d are provided opposing thereto, respectively. A predetermined portion of the intermediate transfer belt 7 is sandwiched between the respective primary transfer rollers 13a, 13b, 13c, and 13d and the respective photosensitive drums 2a, 2b, 2c, and 2d. The sandwiched predetermined portion is pressed to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d.
Primary transfer nips N1a, N1b, N1c, and N1d are formed between the photosensitive drums 2a, 2b, 2c, and 2d and the primary transfer rollers 13a, 13b, 13c, and 13d, respectively. At the primary transfer nips N1a, N1b, N1c, and N1d, toner images for respective colors developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially primarily transferred onto the intermediate transfer belt 7. Thus, a four-full-color toner image is formed on the intermediate transfer belt 7.
It is noted that as described later, the primary transfer rollers 13a, 13b, and 13c, the driven roller 16, and a tension roller 19 are provided so as to be movable in the up-down direction in
In the printer 1, upon formation of a four-full-color toner image, the primary transfer rollers 13a, 13b, and 13c, the driven roller 16, and the tension roller 19 are moved downward in
In addition, in the printer 1, upon formation of a monochrome toner image, the primary transfer rollers 13a, 13b, and 13c, the driven roller 16, and the tension roller 19 are moved upward in
In
In addition, in
A primary transfer bias applying portion (not shown) applies, to the primary transfer rollers 13a, 13b, 13c, and 13d, primary transfer biases for transferring toner images for respective colors formed on the respective photosensitive drums 2a, 2b, 2c, and 2d onto the intermediate transfer belt 7.
The electricity removing devices 12a, 12b, 12c, and 12d are provided facing to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The electricity removing devices 12a, 12b, 12c, and 12d radiate light onto the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d, thereby removing electricity (removing electric charge) on the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d after primary transfer.
The drum cleaning portions 11a, 11b, 11c, and 11d are provided facing to the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d. The drum cleaning portions 11a, 11b, 11c, and 11d remove residual toners or adhered substances on the surfaces of the respective photosensitive drums 2a, 2b, 2c, and 2d, and convey the removed toner and the like to a predetermined recovery mechanism, thus recovering them.
The transfer portion 50 transfers a toner image transferred onto the surface of the intermediate transfer belt 7, onto a paper sheet T. The transfer portion 50 includes the secondary transfer roller 8 and the drive roller 17.
The secondary transfer roller 8 is a roller for secondarily transferring a four-full-color toner image primarily transferred onto the intermediate transfer belt 7, onto a paper sheet T. A secondary transfer bias applying portion (not shown) applies, to the secondary transfer roller 8, a secondary transfer bias for transferring a four-full-color toner image formed on the intermediate transfer belt 7 onto a paper sheet T.
The secondary transfer roller 8 is caused to contact or be separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is configured to be movable to a contact position that causes the secondary transfer roller 8 to contact the intermediate transfer belt 7 or a separation position that causes the secondary transfer roller 8 to be separated from the intermediate transfer belt 7. In detail, the secondary transfer roller 8 is placed at the contact position when a four-full-color toner image or a monochrome toner image primarily transferred onto the surface of the intermediate transfer belt 7 is to be secondarily transferred onto a paper sheet T, and placed at the separation position in the other cases.
The drive roller 17 is provided on a side of the intermediate transfer belt 7 opposite to the secondary transfer roller 8.
A predetermined portion of the intermediate transfer belt 7 is sandwiched between the secondary transfer roller 8 and the drive roller 17. A secondary transfer nip N2 is formed between the intermediate transfer belt 7 and the secondary transfer roller 8. At the secondary transfer nip N2, a paper sheet T is pressed to the outer surface (surface onto which a toner image has been transferred) of the intermediate transfer belt 7. At the secondary transfer nip N2, a four-full-color toner image primarily transferred onto the intermediate transfer belt 7 is secondarily transferred onto a paper sheet T.
The fixing portion 60 melts and pressurizes toners for respective colors forming a toner image secondarily transferred onto a paper sheet T, thereby fixing the toners on the paper sheet T. The fixing portion 60 includes a heating rotary body 60a to be heated by a heater (not shown), and a pressurizing rotary body 60b to be pressed to the heating rotary body 60a. The heating rotary body 60a and the pressurizing rotary body 60b sandwich a paper sheet T having a toner image secondarily transferred thereon, to pressurize the paper sheet T, while conveying the paper sheet T downstream. When the paper sheet T is conveyed being sandwiched between the heating rotary body 60a and the pressurizing rotary body 60b, the toner transferred thereon is melted and pressurized. Thus, the toner transferred onto the paper sheet T is fixed on the surface of the paper sheet T.
Next, the sheet feed/discharge portion 40 will be described. As shown in
The manual sheet feed portion 64 for containing a paper sheet T is provided on a left side surface (at the left in
The conveyance path L for conveying a paper sheet T includes the first conveyance path L1 from the cassette sheet feed portion 51 to the secondary transfer nip N2, the second conveyance path L2 from the secondary transfer nip N2 to the fixing portion 60, the third conveyance path L3 from the fixing portion 60 to the sheet discharge portion 61, the manual conveyance path La which passes a paper sheet fed from the manual sheet feed portion 64 to merge into the first conveyance path L1, and the return conveyance path Lb which returns a paper sheet conveyed from downstream to upstream on the third conveyance path L3 to the first conveyance path L1 while inverting the paper sheet.
The first conveyance path L1 conveys a paper sheet T contained in the sheet feed cassette 52 to the image forming portion 30. The manual conveyance path La conveys a paper sheet T contained in the manual sheet feed portion 64 to the registration roller pair 80 described later.
In addition, a first merging portion P1 and a second merging portion P2 are provided on the first conveyance path L1, and a first branching portion Q1 is provided on the third conveyance path L3.
The first merging portion P1 is a merging portion where the manual conveyance path La merges into the first conveyance path L1. The second merging portion P2 is a merging portion where the return conveyance path Lb merges into the first conveyance path L1. The first branching portion Q1 is a branching portion where the return conveyance path Lb branches from the third conveyance path L3.
On the first conveyance path L1 (in detail, between the second merging portion P2 and the secondary transfer roller 8), a sheet detection sensor (not shown) for detecting a paper sheet T, and a registration roller pair 80 for correcting skew (oblique sheet feed) of a paper sheet T or adjusting a timing in accordance with formation of a toner image by the image forming portion 30, are provided. The sheet detection sensor is provided immediately before (on the upstream side in the conveyance direction) the registration roller pair 80 in the conveyance direction of a paper sheet T. The registration roller pair 80 performs the above correction or timing adjustment based on detected signal information from the sheet detection sensor, to convey a paper sheet T.
A first conveying roller pair 82 is provided between the first merging portion P1 and the second merging portion P2 on the first conveyance path L1. The first conveying roller pair 82 is provided on the downstream side of the sheet feed roller pair 81, and holds and conveys a paper sheet T conveyed by the sheet feed roller pair 81, to the registration roller pair 80.
The return conveyance path Lb is a conveyance path provided for, upon both-side printing on a paper sheet T, causing a side (not printed yet) of the paper sheet T opposite to a side on which printing has been already performed, to face to the intermediate transfer belt 7. A plurality of second conveying roller pairs 83 for conveying a paper sheet T to the second merging portion P2 are provided at predetermined intervals on the return conveyance path Lb. The return conveyance path Lb can invert a paper sheet T conveyed from the first branching portion Q1 to the sheet discharge portion 61 side, and return the paper sheet T to the first conveyance path L1, thus conveying the paper sheet T to the upstream side of the registration roller pair 80 provided on the upstream side of the secondary transfer roller 8. At the secondary transfer nip N2, a predetermined toner image is transferred onto a side on which printing has not been performed yet, of the paper sheet T inverted by the return conveyance path Lb.
A rectification member 58 is provided on the first branching portion Q1. The rectification member 58 rectifies the conveyance direction of a paper sheet T conveyed from the fixing portion 60 through the third conveyance path L3 from upstream to downstream, so as to be directed toward the sheet discharge portion 61, and rectifies the conveyance direction of a paper sheet T conveyed from the sheet discharge portion 61 through the third conveyance path L3 from downstream to upstream, so as to be directed toward the return conveyance path Lb.
The sheet discharge portion 61 is formed at the end of the third conveyance path L3. The sheet discharge portion 61 is provided on the upper side of the apparatus main body M. The sheet discharge portion 61 opens toward the left side surface (leftward in
A discharged sheet accumulation portion M1 is formed on the opening side of the sheet discharge portion 61. The discharged sheet accumulation portion M1 is formed on the upper surface (outer surface) of the apparatus main body M. The discharged sheet accumulation portion M1 is a portion of the upper surface of the apparatus main body M, that is recessed downward. The bottom surface of the discharged sheet accumulation portion M1 is formed by a top cover member M2 which forms a part of the upper surface of the apparatus main body M. Paper sheets T discharged from the sheet discharge portion 61 after predetermined toner images have been formed thereon are stacked and accumulated on the upper surface of the top cover member M2 forming the discharged sheet accumulation portion M1. It is noted that sensors (not shown) for sheet detection are provided at predetermined positions on the conveyance paths.
Next, the belt device 20 will be described. The belt device 20 is a device capable of rotating the intermediate transfer belt 7 and correcting meandering of the belt. The belt device 20 includes the intermediate transfer belt 7, the driven roller 16, the drive roller 17, the first drive motor 18, the tension roller 19, a belt sensor 21 as position information acquiring portion, a roller position adjustment mechanism 22, and a support roller 23 (see
The intermediate transfer belt 7 is an endless belt extending over a plurality of rollers including the driven roller 16, the drive roller 17, the tension roller 19, and the like. Toner images for respective colors are primarily transferred onto the intermediate transfer belt 7 from the primary transfer rollers 13a, 13b, 13c, and 13d. In addition, the toner images for respective colors primarily transferred onto the intermediate transfer belt 7 are secondarily transferred onto a paper sheet T at the position of the secondary transfer roller 8.
The driven roller 16 is a roller supporting the intermediate transfer belt 7 in a rotatable manner. The driven roller 16 is supported by the roller position adjustment mechanism 22 (described later).
The drive roller 17 is a roller that supports the intermediate transfer belt 7 in a rotatable manner and rotates the intermediate transfer belt 7. The drive roller 17 rotates in a predetermined direction by a rotational force given by the first drive motor 18.
The first drive motor 18 is a device that gives a rotational force to the drive roller 17. The first drive motor 18 is electrically connected to the control portion 100 (described later). The rotation speed of the first drive motor 18 is controlled by a drive signal outputted from the control portion 100.
The tension roller 19 is a roller that energizes the intermediate transfer belt 7 from inside to outside. The energizing force by the tension roller 19 gives a predetermined tension to the intermediate transfer belt 7.
The driven roller 16 and the drive roller 17 are set such that their respective rotary shafts (with no references) are parallel to each other, and provided at positions opposite to each other in the longitudinal direction of the intermediate transfer belt 7. The intermediate transfer belt 7 rotates around a plurality of rollers including the driven roller 16, the drive roller 17, the tension roller 19, and the like along with rotation of the drive roller 17.
Next, a peripheral part including the belt sensor 21 and the roller position adjustment mechanism 22 will be described.
As shown in
In addition, as shown in
Here, the light reception range of the light reception portion 25 will be described. As shown in
The center line a shown in
During rotation of the intermediate transfer belt 7, the control portion (first control portion) 100 described later controls the roller position adjustment mechanism 22 so as to cause the position of the belt end surface 7a to coincide with the target position, thereby correcting (hereinafter, may be referred to as “meandering correction”) meandering of the intermediate transfer belt 7. By the meandering correction, position shift of a toner image when a plurality of toner images are primarily transferred onto the intermediate transfer belt 7 from the photosensitive drums 2a, 2b, 2c, and 2d is suppressed, whereby a four-full-color image with no color shift can be obtained.
When the light receiving elements r1 to r20 have received light radiated by the light emitting portion 24, the light receiving elements r1 to r20 output voltage values corresponding to the light reception amounts as the light amount detection signals to the control portion 100. When light radiated by the light emitting portion 24 is shielded by the belt end surface 7a, the voltage values outputted from the light receiving elements r1 to r20 also vary in accordance with the light shielded amount (light shielding position). The control portion 100 specifies the position of the belt end surface 7a based on the voltage values of the light amount detection signals outputted from the respective light receiving elements r1 to r20.
Specifically, for example, in
As shown in
In addition, as shown in
Further, as shown in
In
The belt sensor 21 detects the position of the belt end surface 7a at predetermined time intervals. The control portion 100 controls the roller position adjustment mechanism 22 so that the position of the belt end surface 7a comes close to the target position (see
As shown in
Therefore, by adjusting the inclination direction (upward/downward) of the rotary shaft 32 of the driven roller 16, the belt end surface 7a can be moved toward the front side in the width direction of the belt or toward the rear side opposite thereto.
In addition, by adjusting the inclination angle of the rotary shaft 32 of the driven roller 16, the speed of movement of the belt end surface 7a toward the front side in the width direction of the belt or toward the rear side opposite thereto can be changed.
As shown in
The second drive motor 38 is a device that gives a rotational force to the gear 37. The second drive motor 38 is formed by a pulse motor. The second drive motor 38 is electrically connected to the control portion 100 (see
The support frame 33 is a member provided in the width direction of the driven roller 16 and extending along the longitudinal direction of the intermediate transfer belt 7. The bearing 34 is provided at one end portion 33a of the support frame 33. In addition, the other end portion 33b of the support frame 33 is supported by the swing support shaft 35. The cam 36 contacts a contact portion (not shown) provided at the one end portion 33a of the support frame 33.
The roller position adjustment mechanism 22 configured as described above moves the belt end surface 7a of the intermediate transfer belt 7 in the width direction of the belt in the following manner. First, the control portion 100 outputs a predetermined number of drive pulses based on a light amount detection signal outputted from the light reception portion 25, thereby generating a drive force on the second drive motor 38. The drive force (rotational force) generated on the second drive motor 38 is transmitted to the gear 37 via the output shaft 39, whereby the gear 37 is rotated. Along with this, the cam 36 formed integrally with the gear 37 swings the one end portion 33a of the support frame 33 based on the swing support shaft 35. Thus, the other end portion 32a of the rotary shaft 32 of the driven roller 16, supported by the bearing 34, is inclined upward or downward based on the one end portion of the rotary shaft 32.
For example, if the other end portion 32a of the rotary shaft 32 of the driven roller 16 is moved downward on the front side, the driven roller 16 is inclined to descend from the rear side to the front side. Therefore, the intermediate transfer belt 7 gradually moves to the front side in the lowering direction along with the rotation thereof. On the other hand, if the other end portion 32a of the rotary shaft 32 of the driven roller 16 is moved upward on the front side, the driven roller 16 is inclined to ascend from the rear side to the front side. Therefore, the intermediate transfer belt 7 gradually moves to the rear side in the lowering direction along with the rotation thereof.
The inclination angle of the rotary shaft 32 of the driven roller 16 can be adjusted by the number of drive pulses outputted from the control portion 100 to the second drive motor 38. In addition, the rotation direction of the second drive motor 38 can be switched by the polarity (+/−) of the drive pulses being changed. By switching the rotation direction of the second drive motor 38, the inclination direction of the rotary shaft 32 of the driven roller 16 can be changed.
The greater the inclination angle of the rotary shaft 32 of the driven roller 16 is made, the faster the movement of the intermediate transfer belt 7 in the width direction becomes. In addition, when the inclination angle is adjusted, the faster the rotation speed of the drive roller 17 is made, the faster the movement of the intermediate transfer belt 7 in the width direction becomes. It is noted that control performed when the control portion 100 corrects meandering of the intermediate transfer belt 7 will be described later.
Next, the configurations of the operation portion 70, the storage portion 75, the movement mechanism portion 90, and the control portion 100 (see
The operation portion 70 has a plurality of keys (not shown). The plurality of keys are operated in such a case of changing the setting or resetting a job of the printer 1, for example. When one of the keys has been operated, the operation portion 70 transmits a signal corresponding to the operated key to the control portion 100. In addition, the operation portion 70 includes a display panel which displays the state of the printer 1, a message, or the like, operation buttons such as a power key and a reset key, and the like (these are not shown).
It is noted that in order to display a message or the like on the display panel, the control portion 100 (described later) controls a display panel drive portion (not shown) to cause the display panel drive portion to supply a drive signal, a timing signal, and the like to the display panel.
The storage portion 75 is composed of a hard disk, a semiconductor memory, and the like. The storage portion 75 stores image data or the like supplied from the above-described external apparatus.
Next, the movement mechanism portion 90 will be described.
The movement mechanism portion 90 includes a frame 91, an eccentric cam 92, and a third drive motor 93.
The frame 91 is a frame member formed substantially in a rectangular U-shape in planar view. The frame 91 supports the primary transfer rollers 13a, 13b, and 13c, the driven roller 16, the drive roller 17, and the tension roller 19 in a rotatable manner, at both ends of each roller in the width direction. The frame 91 is supported so as to be rotatable around a rotary shaft 23a of the support roller 23.
In addition, the frame 91 is energized by a spring 14 as an energizing member in the clockwise direction around the rotary shaft 23a of the support roller 23. The support roller 23 has a function of supporting the frame 91 via the rotary shaft 23a, and a function of retaining the primary transfer nip N1d upon formation of a monochrome toner image.
The eccentric cam 92 is a member for moving the frame 91 to a contact position or a separation position (described later), and fixing the frame 91 at the contact position or the separation position. As shown in
The third drive motor 93 is a device that gives a rotational force to the eccentric cam 92. The third drive motor 93 is electrically connected to the control portion 100 (described later). The rotation of the third drive motor 93 is controlled by a drive signal outputted from the control portion 100.
In the case where four-full-color printing is performed in the printer 1, a rotational force is given from the third drive motor 93 to the eccentric cam 92, to rotate the eccentric cam 92 to a first position at which the major axis direction of the eccentric cam 92 is substantially perpendicular to the intermediate transfer belt 7. When the eccentric cam 92 has rotated to the first position, the frame 91 pressed by the eccentric cam 92 rotates counterclockwise around the rotary shaft 23a of the support roller 23 against the energizing force of the spring 14.
As a result, as shown in
On the other hand, in the case where monochrome printing is performed in the printer 1, a rotational force is given from the third drive motor 93 to the eccentric cam 92, to rotate the eccentric cam 92 to a second position at which the minor axis direction of the eccentric cam 92 is substantially perpendicular to the intermediate transfer belt 7. When the eccentric cam 92 has rotated to the second position, the frame 91 rotates clockwise around the rotary shaft 23a of the support roller 23 by the energizing force of the spring 14.
As a result, as shown in
Next, the control portion 100 will be described. The control portion 100 includes a CPU, a RAM, and a ROM (not shown). The RAM is a storage device having a function of temporarily storing various types of data and a function as a working area upon calculation. The ROM is a storage device having a function as a flash memory for storing various programs. The CPU is a computing device that reads a program from the ROM and executes the program. The CPU, and the RAM and the ROM receive and transmit data with each other via a data bus (not shown). The CPU executes a program read from the ROM and thereby executes processing in accordance with the content of the program. In addition, the control portion 100 has a timer function (hereinafter, may be referred to as a “timer”) of counting time.
The control portion 100 controls the belt device 20, the image forming portion 30, the sheet feed/discharge portion 40, and the movement mechanism portion 90. In addition, the control portion 100 has functions as a first control portion and a second control portion described later. Hereinafter, the control portion 100 when functioning as the first control portion is referred to as a “control portion (first control portion) 100”, and the control portion 100 when functioning as the second control portion is referred to as a “control portion (second control portion) 100”.
The control portion (first control portion) 100 determines an inclination direction and an inclination angle of the rotary shaft of the driven roller 16, based on a light amount detection signal (position information about the transfer belt) outputted from the belt sensor 21 (acquired by the position information acquiring portion), and controls the roller position adjustment mechanism 22 so that the rotary shaft of the driven roller 16 will be directed in the inclination direction at the inclination angle.
Specifically, in the case where the position of the intermediate transfer belt 7 specified based on a light amount detection signal outputted from the belt sensor 21 is within the correction range (detection range A1: see
In addition, in the case where the position of the intermediate transfer belt 7 specified based on a light amount detection signal outputted from the belt sensor 21 is out of the correction range and within the allowable range (detection range A2: see
It is noted that the control portion (first control portion) 100 determines an inclination direction and an inclination angle of the rotary shaft of the driven roller 16 by referring to a data table (ROM) on which light amount detection signals (voltage values) outputted from the belt sensor 21 are respectively associated with inclination directions and inclination angles of the rotary shaft of the driven roller 16 that are required for returning the intermediate transfer belt 7 to the predetermined target position.
In addition, upon the control for the roller position adjustment mechanism 22 in order to return the intermediate transfer belt 7 to the predetermined target position in the second correction, the control portion (first control portion) 100 controls the roller position adjustment mechanism 22 so as to make the inclination angle of the rotary shaft of the driven roller 16 greater than that in the first correction.
In addition, in the emergency case where the position of the intermediate transfer belt 7 specified based on a light amount detection signal outputted from the belt sensor 21 is out (detection range A3: see
Further, in the case where, even though the roller position adjustment mechanism 22 is controlled by the function of the first control portion, the intermediate transfer belt 7 does not return into the correction range centered on the target position within a time t1 (predetermined time) and is out of the correction range, the control portion (second control portion) 100 controls the movement mechanism portion 90 so as to change the positions of the primary transfer rollers 13a, 13b, and 13c (a plurality of second opposing portions).
Specifically, in the state in which the primary transfer rollers 13a, 13b, and 13c (a plurality of second opposing portions) are positioned at the contact positions, in the case where, even though the roller position adjustment mechanism 22 is controlled in accordance with the inclination direction and the inclination angle (correction information) of the rotary shaft of the driven roller 16 by the function of the first control portion, the intermediate transfer belt 7 does not return into the correction range within the time t1 (predetermined time) and is out of the correction range, the control portion (second control portion) 100 controls the movement mechanism portion 90 so as to move the primary transfer rollers 13a, 13b, and 13c to the separation positions.
In addition, in the state in which the primary transfer rollers 13a, 13b, and 13c (a plurality of second opposing portions) are positioned at the separation positions, in the case where, even though the roller position adjustment mechanism 22 is controlled in accordance with the inclination direction and the inclination angle (correction information) of the rotary shaft of the driven roller 16 by the function of the first control portion, the intermediate transfer belt 7 does not return into the correction range within the time t1 (predetermined time) and is out of the correction range, the control portion (second control portion) 100 controls the movement mechanism portion 90 so as to move the primary transfer rollers 13a, 13b, and 13c to the contact positions.
In addition, if the intermediate transfer belt 7 has returned to the correction range by the control for the movement mechanism portion 90 which has changed the positions of the primary transfer rollers 13a, 13b, and 13c (a plurality of second opposing portions), the control portion (second control portion) 100 controls the movement mechanism portion 90 so as to retain the changed positions of the primary transfer rollers 13a, 13b, and 13c.
The functions of the control portion 100 as the first control portion and the second control portion described above will be described later with reference to the flowchart.
Next, the operation of the printer 1 configured as described above will be described. First, with reference to
(Operation in Case of Performing One-Side Printing on Paper Sheet T)
A paper sheet T contained in the sheet feed cassette 52 is fed to the first conveyance path L1 by the forward feed roller 55 and the sheet feed roller pair 81, and then conveyed to the registration roller pair 80 through the first merging portion P1 and the first conveyance path L1 by the first conveying roller pair 82.
On the registration roller pair 80, skew correction of the paper sheet T and timing adjustment in accordance with formation of a toner image in the image forming portion 30 are performed.
The paper sheet T discharged from the registration roller pair 80 is introduced through the first conveyance path L1 to a portion (the secondary transfer nip N2) between the intermediate transfer belt 7 and the secondary transfer roller 8. Then, a toner image is transferred onto the paper sheet T between the intermediate transfer belt 7 and the secondary transfer roller 8.
Thereafter, the paper sheet T is discharged from between the intermediate transfer belt 7 and the secondary transfer roller 8, and then introduced through the second conveyance path L2 to a fixing nip between the heating rotary body 60a and the pressurizing rotary body 60b in the fixing portion 60. Then, at the fixing nip, a toner is melted and fixed on the paper sheet T.
Next, the paper sheet T is conveyed through the third conveyance path L3 to the sheet discharge portion 61, and discharged from the sheet discharge portion 61 to the discharged sheet accumulation portion M1 by the discharge roller pair 53. Thus, the one-side printing of the paper sheet T contained in the sheet feed cassette 52 is completed.
On the other hand, in the case of performing one-side printing on a paper sheet T placed on the manual tray 65, the paper sheet T placed on the manual tray 65 is fed through the manual conveyance path La by the sheet feed roller 66, and then conveyed through the first merging portion P1 and the first conveyance path L1 to the registration roller pair 80. The operation performed thereafter is the same as the above-described operation of the one-side printing on a paper sheet T contained in the sheet feed cassette 52, and therefore the description thereof is omitted.
(Operation in Case of Performing Both-Side Printing on Paper Sheet T)
In the case of one-side printing, as described above, a paper sheet T on which one-side printing has been performed is discharged from the sheet discharge portion 61 to the discharged sheet accumulation portion M1, and thus the printing operation is completed.
On the other hand, in the case of performing both-side printing, a paper sheet T on which one-side printing has been performed is inverted from the side for the one-side printing and conveyed again to the registration roller pair 80 through the return conveyance path Lb, whereby both-side printing is to be performed for the paper sheet T.
In detail, the operation until the paper sheet T on which one-side printing has been performed is discharged from the sheet discharge portion 61 by the discharge roller pair 53 is the same as the operation for the one-side printing described above. However, in the case of both-side printing, in the state in which the paper sheet T on which one-side printing has been performed is held by the discharge roller pair 53, rotation of the discharge roller pair 53 is stopped and then the discharge roller pair 53 is caused to rotate in the reverse direction. If the discharge roller pair 53 is thus rotated in the reverse direction, the paper sheet T held by the discharge roller pair 53 is conveyed in the reverse direction (direction from the sheet discharge portion 61 to the first branching portion Q1) through the third conveyance path L3.
As described above, if the paper sheet T is conveyed in the reverse direction through the third conveyance path L3, the paper sheet T is rectified into the return conveyance path Lb by the rectification member 58, and then merges into the first conveyance path L1 via the second merging portion P2. Here, the paper sheet T has been inverted from the side for the one-side printing.
Further, the paper sheet T is subjected to the correction or the adjustment by the registration roller pair 80, and then introduced through the first conveyance path L1 into the secondary transfer nip N2. Since a side of the paper sheet T on which printing has not been performed yet faces to the intermediate transfer belt 7 as a result of passing through the return conveyance path Lb, a toner image is transferred onto the side on which printing has not been performed yet, whereby both-side printing is performed.
Next, the processing procedure in the case where the control portion (first control portion and second control portion) 100 executes meandering correction for the intermediate transfer belt 7 will be described.
In step ST101 shown in
In step ST102, the control portion (first control portion) 100 specifies the position (hereinafter, may be referred to as a “detected belt position”) of the belt end surface 7a of the intermediate transfer belt 7 based on the acquired light amount detection signal.
In step ST103, the control portion (first control portion) 100 determines whether or not the detected belt position is within the correction range (detection range A1). In step ST103, if the control portion (first control portion) 100 has determined that the detected belt position is within the correction range (YES), the control portion (first control portion) 100 advances the process to step ST104. On the other hand, in step ST103, if the control portion (first control portion) 100 has determined that the detected belt position is out of the correction range (NO), the control portion (first control portion) 100 advances the process to step ST105.
In step ST104 (determined YES in step ST103), the control portion (first control portion) 100 executes the first correction (meandering correction in a normal case), whereby the process of the present flowchart is ended. In the first correction, the control portion (first control portion) 100 determines a drive direction and a drive amount of the second drive motor 38 in accordance with the detected belt position, and outputs a drive signal with a drive pulse number corresponding to the drive direction and the drive amount, to the second drive motor 38. In addition, the control portion (first control portion) 100 controls the rotation speed of the first drive motor 18 so that the rotation speed (belt movement speed) of the drive roller 17 will become a speed for the first correction. Therefore, the intermediate transfer belt 7 rotates at the movement speed for the first correction.
On the other hand, in step ST105 (determined NO in step ST103), the control portion (first control portion) 100 determines whether or not the detected belt position is out of the correction range (detection range A1) and within the allowable range (detection range A2). In step ST105, if the control portion (first control portion) 100 has determined that the detected belt position is out of the correction range and within the allowable range (YES), the control portion (first control portion) 100 advances the process to step ST106. On the other hand, in step ST105, if the control portion (first control portion) 100 has determined that the detected belt position is out of the correction range and not within the allowable range (NO), the control portion (first control portion) 100 advances the process to step ST108.
In step ST106 (determined YES in step ST105), the control portion (first control portion) 100 controls the belt device 20 to stop output of a drive signal to the first drive motor 18, whereby the printer 1 interrupts print processing. At the same time, the control portion (first control portion) 100 controls the display panel drive portion (not shown) to display, on the display panel (not shown) of the operation portion 70, a message for notifying that the print processing is interrupted because meandering correction for the belt is being performed.
In step ST107, the control portion (first control portion) 100 executes the second correction (meandering correction in an abnormal case). Specifically, the control portion (first control portion) 100 sets a drive amount of the second drive motor 38 to the maximum value irrespective of the detected belt position, and outputs a drive signal with a drive pulse number corresponding to the maximum drive amount, to the second drive motor 38. As a result, the inclination angle of the rotary shaft 32 of the driven roller 16 becomes greater than the inclination angle set for the first correction.
In addition, in step ST107, the control portion (first control portion) 100 controls the rotation speed of the first drive motor 18 to the maximum value so that the rotation speed (belt movement speed) of the drive roller 17 will become faster than that for the first correction. As a result, the rotation speed of the first drive motor 18 becomes faster than that for the first correction. Therefore, the intermediate transfer belt 7 rotates at a speed (high speed) faster than the movement speed for the first correction.
On the other hand, in step ST108 (determined NO in step ST105), the control portion (first control portion) 100 executes processing for emergency. Specifically, the control portion (first control portion) 100 controls the belt device 20 to stop output of a drive signal to the first drive motor 18, whereby the printer 1 interrupts print processing (emergency stop). At the same time, the control portion (first control portion) 100 controls the display panel drive portion (not shown) to display, on the display panel (not shown) of the operation portion 70, a message for notifying that the print processing is interrupted because of abnormal meandering of the belt. Then, the process of the present flowchart is ended.
It is noted that in step ST108, the control portion (first control portion) 100 may control the display panel drive portion (not shown) to display, on the display panel of the operation portion 70, a message for notifying that inspection by a maintenance staff is needed, together with the message for notifying that the print processing is interrupted.
In step ST109 shown in
In step ST110, the control portion (second control portion) 100 determines whether or not the time counted by the timer has reached the time t1. In the determination of step ST110, if the control portion (second control portion) 100 has determined that the time counted by the timer has reached the time t1 (YES), the control portion (second control portion) 100 advances the process to step ST111. It is noted that the count of the timer is reset when the time counted by the timer has reached the time t1.
On the other hand, in the determination of step ST110, if the control portion (second control portion) 100 has determined that the time counted by the timer has not reached the time t1 yet (NO), the control portion (second control portion) 100 returns the process to step ST110.
In step ST111 (determined YES in step ST110), the control portion (second control portion) 100 acquires a light amount detection signal from the light reception portion 25 (belt sensor 21).
In step ST112, the control portion (second control portion) 100 specifies the detected belt position of the intermediate transfer belt 7 based on the acquired light amount detection signal.
In step ST113, the control portion (second control portion) 100 determines whether or not the detected belt position is within the correction range (detection range A1). In step ST113, if the control portion (second control portion) 100 has determined that the detected belt position is within the correction range (YES), the control portion (second control portion) 100 advances the process to step ST104 (see
In step ST114 (determined NO in step ST113), the control portion (second control portion) 100 determines whether or not the intermediate transfer belt 7 is positioned at the contact position where the intermediate transfer belt 7 contacts the photosensitive drums 2a, 2b, and 2c. In step ST114, if the control portion (second control portion) 100 has determined that the intermediate transfer belt 7 is positioned at the contact position (YES), the control portion (second control portion) 100 advances the process to step ST115. On the other hand, in step ST114, if the control portion (second control portion) 100 has determined that the intermediate transfer belt 7 is not positioned at the contact position (NO), that is, is positioned at the separation position, the control portion (second control portion) 100 advances the process to step ST116.
In step ST115 (YES in step ST114), the control portion (second control portion) 100 controls the movement mechanism portion 90 to change the position of the intermediate transfer belt 7 from the contact position to the separation position (move the primary transfer rollers 13a to 13c to the separation positions).
In step ST116 (NO in step ST114), the control portion (second control portion) 100 controls the movement mechanism portion 90 to change the position of the intermediate transfer belt 7 from the separation position to the contact position (move the primary transfer rollers 13a to 13c to the contact positions).
In step ST117 shown in
In step ST118, the control portion (second control portion) 100 determines whether or not the time counted by the timer has reached the time t2. In the determination of step ST118, if the control portion (second control portion) 100 has determined that the time counted by the timer has reached the time t2 (YES), the control portion (second control portion) 100 advances the process to step ST119. It is noted that the count of the timer is reset when the time counted by the timer has reached the time t2.
On the other hand, in the determination of step ST118, if the control portion (second control portion) 100 has determined that the time counted by the timer has not reached the time t2 yet (NO), the control portion (second control portion) 100 returns the process to step ST118.
In step ST119 (YES in step ST118), the control portion (second control portion) 100 acquires a light amount detection signal from the light reception portion 25 (belt sensor 21).
In step ST120, the control portion (second control portion) 100 specifies the detected belt position of the intermediate transfer belt 7 based on the acquired light amount detection signal.
In step ST121, the control portion (second control portion) 100 determines whether or not the detected belt position is out of the correction range (detection range A1). In step ST121, if the control portion (second control portion) 100 has determined that the detected belt position is out of the correction range (YES), the control portion (second control portion) 100 advances the process to step ST108 (see
On the other hand, in step ST121, if the control portion (second control portion) 100 has determined that the detected belt position is within the correction range (NO), the control portion (second control portion) 100 advances the process to step ST122.
In step ST122 (NO in step ST121), the control portion (second control portion) 100 determines whether or not the intermediate transfer belt 7 is positioned at the contact position where the intermediate transfer belt 7 contacts the photosensitive drums 2a, 2b, and 2c. In step ST122, if the control portion (second control portion) 100 has determined that the intermediate transfer belt 7 is positioned at the contact position (YES), the control portion (second control portion) 100 advances the process to step ST123. On the other hand, in step ST122, if the control portion (second control portion) 100 has determined that the intermediate transfer belt 7 is not positioned at the contact position (NO), that is, is positioned at the separation position, the control portion (second control portion) 100 advances the process to step ST125.
In step ST123 (YES in step ST122), the control portion (second control portion) 100 fixes the position of the intermediate transfer belt 7 at the contact position. Specifically, the control portion (second control portion) 100 retains the status of a flag set in a predetermined area of the RAM and indicating that the intermediate transfer belt 7 has moved to the contact position.
In step ST124, the control portion (second control portion) 100 sets the print mode to four-full-color printing, and controls the belt device 20 to output a drive signal to the first drive motor 18. Thus, in the printer 1, the belt device 20 is driven and four-full-color printing is restarted. At the same time, the control portion (second control portion) 100 controls the display panel drive portion (not shown) to display, on the display panel (not shown) of the operation portion 70, a message for informing that four-full-color printing is able to be performed, whereby the process of the present flowchart is ended.
On the other hand, in step ST125 (NO in step ST122), the control portion (second control portion) 100 fixes the position of the intermediate transfer belt 7 at the separation position. Specifically, the control portion (second control portion) 100 retains the status of a flag set in a predetermined area of the RAM and indicating that the intermediate transfer belt 7 has moved to the separation position.
In step ST126, the control portion (second control portion) 100 sets the print mode to monochrome printing, and controls the belt device 20 to output a drive signal to the first drive motor 18. Thus, in the printer 1, the belt device 20 is driven and monochrome printing is restarted. At the same time, the control portion (second control portion) 100 controls the display panel drive portion (not shown) to display, on the display panel (not shown) of the operation portion 70, a message for informing that monochrome printing is able to be performed, whereby the process of the present flowchart is ended.
It is noted that in steps ST124 and ST126, the control portion (second control portion) 100 may control the display panel drive portion (not shown) to display, on the display panel of the operation portion 70, a message for notifying that inspection by a maintenance staff is needed, together with the message for notifying that four-full-color printing or monochrome printing is able to be performed.
Next, a specific example in which the control portion (first control portion and second control portion) 100 performs meandering correction for the intermediate transfer belt 7 based on the process of the flowcharts shown in
First, the case where the intermediate transfer belt 7 falls within the correction range by the second correction (meandering correction in an abnormal case) will be described.
It is noted that dotted-dashed lines “a”, “b1” and “b2” shown in
As shown in
In addition, when the position of the belt end surface 7a of the intermediate transfer belt 7 is out of the correction range (detection range A1) and within the allowable range (detection range A2) (interval S2), the second correction (meandering correction in an abnormal case) is executed. Here, in the conventional meandering correction (see
On the other hand, in the meandering correction (see
Thus, the meandering correction of the present embodiment shown in
Next, the case where the intermediate transfer belt 7 does not fall within the correction range even after the second correction is performed for a predetermined time will be described.
As shown in
Then, if the position of the belt end surface 7a of the intermediate transfer belt 7 does not return into the correction range (detection range A1) even after the second correction is performed for the time t1 in the interval S2 as shown in
Thereafter, as shown in
On the other hand, as shown in
Then, if the position of the belt end surface 7a of the intermediate transfer belt 7 does not return into the correction range (detection range A1) even after the second correction is performed for the time t1 in the interval S2 as shown in
Thereafter, as shown in
The tendency of the above-described meandering of the intermediate transfer belt 7 varies between the cases where the intermediate transfer belt 7 is positioned at the contact position and the separation position with respect to the photosensitive drums 2a to 2c. It is considered that this is because, when the intermediate transfer belt 7 is made contact with or separate from the photosensitive drums 2a to 2c, a conveyance speed difference due to torsion or change in tension of the intermediate transfer belt 7 occurs on the front side or the rear side of the intermediate transfer belt 7.
Therefore, in the case where the intermediate transfer belt 7 does not return into the correction range even after the second correction is performed for a predetermined time (time t1), if the positional relationship (contact/separation) between the photosensitive drums 2a to 2c and the intermediate transfer belt 7 is changed, the tendency of meandering of the intermediate transfer belt 7 can be changed. Therefore, in the second correction, in the case where the intermediate transfer belt 7 does not return into the correction range, if the positional relationship between the photosensitive drums 2a to 2c and the intermediate transfer belt 7 is changed, the possibility that the intermediate transfer belt 7 will return into the correction range increases.
Then, in the case where the intermediate transfer belt 7 has returned into correction range after the positional relationship between the photosensitive drums 2a to 2c and the intermediate transfer belt 7 has been changed, if the positional relationship between the photosensitive drums 2a to 2c and the intermediate transfer belt 7 at this time is fixed, the printer 1 can be driven in either print mode of color printing or monochrome printing.
The printer 1 according to the above embodiment provides the following effects, for example.
In the printer 1 according to the present embodiment, in the case where the intermediate transfer belt 7 does not return into the correction range even though the roller position adjustment mechanism 22 is controlled by the function of the first control portion so as to correct meandering of the intermediate transfer belt 7, the control portion (second control portion) 100 controls the movement mechanism portion 90 so as to change the positions of the primary transfer rollers 13a to 13c (a plurality of second opposing portions).
Thus, in the second correction, if the intermediate transfer belt 7 does not return into the correction range, the positions of the primary transfer rollers 13a to 13c are changed, whereby the possibility that the intermediate transfer belt 7 will return into the correction range increases. Then, if the intermediate transfer belt 7 has returned into the correction range after the positions of the primary transfer rollers 13a to 13c have been changed, the printer 1 can be driven in either print mode of color printing or monochrome printing in accordance with the positions of the primary transfer rollers 13a to 13c at this time. Therefore, when abnormal meandering of the intermediate transfer belt 7 has occurred, the printer 1 according to the present embodiment can prevent, as much as possible, occurrence of the state in which neither color printing nor monochrome printing can be performed.
In addition, if the intermediate transfer belt 7 has returned into the correction range after the movement mechanism portion 90 has been controlled so as to change the positions of the primary transfer rollers 13a to 13c, the control portion (second control portion) 100 retains the changed positions of the primary transfer rollers 13a to 13c.
Thus, if the intermediate transfer belt 7 has returned into the correction range after the positions of the primary transfer rollers 13a to 13c have been changed, the positions of the primary transfer rollers 13a to 13c at this time are retained, whereby the printer 1 can be continuously driven by either print mode of color printing or monochrome printing.
In addition, in the case where the intermediate transfer belt 7 does not return into the correction range even though the roller position adjustment mechanism 22 has been controlled by the function of the first control portion so as to correct meandering of the intermediate transfer belt 7, if the positions of the primary transfer rollers 13a to 13c are the contact positions, the control portion (second control portion) 100 controls the movement mechanism portion 90 so that the positions of the primary transfer rollers 13a to 13c will become the separation positions.
Thus, in the case where the positions of the primary transfer rollers 13a to 13c are the contact positions (four-full-color printing), if the intermediate transfer belt 7 does not return into the correction range, the positions of the primary transfer rollers 13a to 13c become the separation positions (monochrome printing). Therefore, the printer 1 can execute monochrome printing.
In addition, in the case where the intermediate transfer belt 7 does not return into the correction range even though the roller position adjustment mechanism 22 has been controlled by the function of the first control portion so as to correct meandering of the intermediate transfer belt 7, if the positions of the primary transfer rollers 13a to 13c are the separation positions, the control portion (second control portion) 100 controls the movement mechanism portion 90 so that the positions of the primary transfer rollers 13a to 13c will become the contact positions.
Thus, in the case where the positions of the primary transfer rollers 13a to 13c are the separation positions (monochrome printing), if the intermediate transfer belt 7 does not return into the correction range, the positions of the primary transfer rollers 13a to 13c become the contact positions (four-full-color printing). Therefore, the printer 1 can execute four-full-color printing. In addition, in this case, the printer 1 can also execute monochrome printing as well as four-full-color printing.
In addition, the control portion (first control portion) 100 determines an inclination direction and an inclination angle of the rotary shaft of the driven roller 16 in accordance with the position of the intermediate transfer belt 7 detected by the belt sensor 21, and controls the roller position adjustment mechanism 22 so that the rotary shaft of the driven roller 16 will be directed in the inclination direction at the inclination angle.
Therefore, in accordance with the position of the meandering intermediate transfer belt 7, the intermediate transfer belt 7 can be swiftly returned into the correction range.
Although preferred embodiments of the present disclosure have been thus described, the present disclosure is not limited to the above embodiments but may be carried out in various modes.
The movement mechanism portion 90 of the present embodiment includes the eccentric cam 92 and the third drive motor 93 as a mechanism for moving the frame 91 supporting the primary transfer rollers 13a to 13c to the contact position or the separation position with respect to the photosensitive drums 2a to 2c. Instead, the movement mechanism portion 90 may be formed by a drive motor and a gear mechanism. In this case, the gear mechanism is rotated by a rotational force of the drive motor, whereby the frame 91 supported by the rotary shaft 23a of the support roller 23 can be moved to the contact position or the separation position.
The movement mechanism portion 90 may be formed by a rod and an actuator linked with the frame 91. In this case, the rod is driven by motive power generated by the actuator, whereby the frame 91 supported by the rotary shaft 23a of the support roller 23 can be moved to the contact position or the separation position.
The control portion (first control portion) 100 of the present embodiment determines an inclination direction and an inclination angle of the rotary shaft of the driven roller 16 by referring to a data table (ROM) on which light amount detection signals (voltage values) outputted from the belt sensor 21 are respectively associated with inclination directions and inclination angles of the rotary shaft of the driven roller 16 that are required for returning the intermediate transfer belt 7 to a predetermined target position. Instead, an inclination direction and an inclination angle of the rotary shaft of the driven roller 16 may be calculated by a calculation expression using a light amount detection signal (voltage value) as a parameter.
In the present embodiment, an example where the image forming apparatus according to the present disclosure is applied to a printer capable of four-full-color printing and monochrome printing, has been described. Instead, the present disclosure can be applied to general image forming apparatuses configured such that an endless belt can be moved to a contact position and a separation position with respect to a photosensitive drum. For example, the present disclosure can be applied to a copy machine, a facsimile machine, or the like having such a configuration.
It is to be understood that the embodiments herein are illustrative and not restrictive, since the scope of the disclosure is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-239088 | Oct 2012 | JP | national |
