JP2017021170A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, in a system in which an opposing roller of a transfer cleaning blade serves as a tension (driven) roller of a transfer belt as well, a change in attitude of the blade occurring due to a separation operation of a primary transfer roller by rotating the belt in a reverse direction and prevent chattering and turning-up of the cleaning blade.SOLUTION: During steps from full-color output to standby for subsequent output, prior to the state of standby for subsequent output after transition from a total separation state to a Bk single mode (HP), an image forming apparatus rotates a transfer belt in a reverse direction (forward rotation for a driving direction of a cleaning blade, and reverse direction for a driving direction of the transfer belt) and makes a transition to the state of standby for subsequent output.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tandem type image forming apparatus provided with a cleaner blade that cleans the surface of a transfer belt by bringing its tip into contact with the surface of a moving transfer belt, and an image forming method in the apparatus.

  As an image forming apparatus such as a copying machine, a printer, or a facsimile, for example, an image forming station that forms toner images of different colors along a transfer belt conveyed in a predetermined direction as disclosed in Patent Document 1 below. There is known a so-called tandem type image forming apparatus in which a plurality of image forming devices are arranged. In such an image forming apparatus, a color image is formed by superimposing toner images of different colors formed by a plurality of image forming stations on the surface of a transfer belt. The color image formed on the belt surface is transferred to a transfer medium such as paper.

  In such an image forming apparatus, a cleaner blade may be provided to remove toner remaining on the surface of the transfer belt. The cleaner blade removes residual toner from the surface of the transfer belt by bringing its tip into contact with the surface of the transfer belt conveyed in a predetermined direction.

  However, there are cases where foreign matters such as paper dust adhere to the transfer belt surface in addition to the residual toner. Most of such foreign matter is removed from the transfer belt surface by the cleaner blade in the same manner as the residual toner. However, some foreign matter adheres to the tip of the cleaner blade and is between the tip of the cleaner blade and the transfer belt surface. It may get caught. As a result, a gap is formed between the cleaner blade and the surface of the transfer belt, and the residual toner may slip through the gap, so that the residual toner may not be removed satisfactorily.

  For this reason, as shown in Patent Document 1 below, the driven roller with which the cleaner blade abuts is urged in the urging direction D, and a plurality of transfer members are positioned at the image forming stations Y, M, C, and K for transfer. The belt is pushed against and contacted with the image forming stations Y, M, C, and K by pressing the primary transfer roller, and the transfer member (primary transfer) is moved away from the image forming station as necessary. At the position where the cleaner blade comes into contact with the transfer belt due to this separation movement, the transfer belt moves in the direction opposite to the conveying direction, and the foreign matter adhering to the cleaning blade is temporarily moved from the position where the cleaning blade and the transfer belt are in contact with each other. By releasing and rubbing, foreign matter adhering to the cleaning blade is removed.

  Further, in Patent Document 2, when applied to an apparatus for cleaning the transfer belt surface with a cleaner blade, there is provided a reverse rotation mechanism in the drive system of the transfer belt, and means for separating foreign matter adhering to the tip of the cleaner blade. An apparatus structure has been proposed which is realized with a simple configuration.

Japanese Unexamined Patent Publication No. 2007-9378 JP 2004-102178 A

  In view of the above prior art, the following configuration has been proposed in order to avoid complication and enlargement of the apparatus.

As a method of separating the primary transfer roller,
・ The transfer belt drive motor and the separation motor are separated by a single motor. ・ To shorten the time from printing start in Bk single color mode to paper discharge and to reduce the load on other stations in Bk single color mode. A state in which the primary transfer roller only in the Bk station is pressed is defined as a home position (hereinafter referred to as HP).

・ In order to maintain the switching speed from Bk single color mode to full color output, in the same drive, full color (all stations) → all separated → Bk (HP) → full color (all stations) The primary transfer roller is separated.
1. At that time, the behavior of the cleaning blade 140 of the intermediate transfer belt 136 in the process until the next output standby after full color output is as follows.
2. Full color (all stations) → looseness of the intermediate transfer belt 136 at the time of full separation is corrected by the driven tension roller 137d in FIG. Further, since the belt is sandwiched between the two-roller roller 138 and the drive roller 137a, the belt moves in the forward direction (reverse to the drive direction) with respect to the cleaning blade 140. The toner or the like is moved to the upstream side of the cleaning blade 140 and stopped.
3. At the time of transition from all separation to Bk single color mode (HP), the belt moves in the counter direction (forward direction with respect to the driving direction) with respect to the cleaning blade 140 contrary to the above. At the time of operation when fully separated, the amount of movement of the intermediate transfer belt 136 at the position of the cleaning blade 140 is reduced, and the contact between the cleaning blade 140 and the intermediate transfer belt 136 is depleted of lubricant. Thus, the cleaning blade 140 is stopped while the posture of the cleaning blade 140 is retracted with respect to the driving direction of the intermediate transfer belt 136. 1. The cleaning blade 140 is restrained in a state where the posture of the cleaning blade 140 is retracted with respect to the driving direction of the intermediate transfer belt 136. When the lubricant is insufficient at the contact portion between the cleaning blade and the transfer belt, there is a possibility that start-up wrinkles and chatter may occur.

An image forming method according to the present invention includes:
In the process until the next output standby after the full color output,
After the transition from the fully separated state to the Bk single mode (HP), before the next output standby state, the transfer belt is reversely rotated (from the cleaning blade, forward rotation / reverse rotation from the transfer belt drive direction). , And the next output standby state.

  According to the image forming method of the present invention, in the system in which the opposing roller of the cleaning blade also serves as the tension roller (driven) of the transfer belt, the belt rotates reversely due to the blade posture change caused by the separation operation of the primary transfer roller. This eliminates chattering / turning of the transfer cleaning blade.

1 is an overall configuration diagram of an image forming apparatus according to Embodiment 1. FIG. 1 is an overall configuration diagram of an image forming apparatus when a primary transfer roller is completely separated according to Embodiment 1. FIG. 1 is an overall configuration diagram of an image forming apparatus of a Bk single color mode according to Embodiment 1. Operation flowchart at the end of the brewing operation according to the first embodiment Overall configuration diagram of the image forming apparatus of S4 in the operation flowchart at the end of the brewing operation according to the first embodiment The figure which shows the state of the contact position vicinity of the cleaning blade 140 of S4 of the operation | movement flowchart at the time of completion | finish of the brewing operation | movement which concerns on this Example 1. FIG. Overall configuration diagram of the image forming apparatus of S5 and S7 in the operation flowchart at the end of the brewing operation according to the first embodiment The figure which shows the state of the contact position vicinity of the cleaning blade 140 of S5 and S7 of the operation | movement flowchart at the time of the end of the brewing operation | movement which concerns on this Example 1. FIG. FIG. 6 is an overall configuration diagram of the image forming apparatus in S6 in the operation flowchart at the end of the brewing operation according to the first embodiment. The figure which shows the state of the contact position vicinity of the cleaning blade 140 of S6 of the operation | movement flowchart at the time of the end of the brewing operation | movement which concerns on this Example 1. FIG.

[Example 1]
FIG. 1 shows the configuration of a first embodiment of the image forming apparatus of the present invention. The printer uses an electrophotographic image forming process to display an image represented by image forming data input from an image input terminal (for example, image data read by a scanner or print data input from a personal computer). Then, a visible image is formed (printed) on a recording medium such as plain paper or thermal paper, that is, copied.

  Inside the main unit 102 in the printer main body, a print engine as a digital printing system, a scanning output system 103, a cartridge unit 105 in which toner cartridges for each color of Y 1, M 2, C 3, and K are arranged, and a recording paper are scanned A standard transport system 107 made up of various roller members for accommodating the output system 103 and discharging recording paper printed by the scanning output system is accommodated.

  The first paper feed tray 190 disposed under the main unit 102 includes various rollers 19 2 (a pickup roller 192 a and a feed roller pair 192 b) and various paper sensors 194 (paper remaining level sensor 194 a). And a paper sheet detection sensor 194 b) and a tray table 1 9 9, and a sheet for storing a recording sheet of a predetermined size (it is possible to cope with a plurality of sizes by changing the position of the stopper) Cassette 198.

  The feeder unit 196 feeds recording sheets from the sheet cassette 198 one by one and sends them to the standard transport system 107 in the main unit 102.

  The scanning output system 103 transfers an image to an intermediate transfer member belt, which is an example of a first transfer material, using a drum, which is a photosensitive member, and a primary transfer roller, which is an example of a first image carrier. By using an intermediate transfer belt as a second image carrier, a transfer image portion of the intermediate transfer belt and a recording sheet as an example of an output medium as a second transfer material are sandwiched between secondary transfer roller pairs. In this configuration, an image is printed (formed) on a recording medium by transferring the image onto a recording sheet.

  That is, the scanning output system 103 first attaches the Y 1, M 2, C 3, and K color print execution units 130 (Y, M 1, C 3, and K respectively) that are juxtaposed at a constant interval in one direction; The same applies to the above; when referring collectively, the color is omitted).

  The print execution unit 130 contacts and transfers the toner image formed on the photosensitive drum 131 which is the first image carrier to the intermediate transfer belt 136 which is the first transfer material and which is the second image carrier. It functions as a first transfer part.

  A photosensitive drum 131 is disposed at the center of the print execution unit 130, and around the photosensitive drum 131, a cleaner 132 that collects toner remaining without being transferred onto the photosensitive drum 131, and a photosensitive drum. A primary charger 133 that uniformly charges the surface of the body drum 131 to the same polarity as the toner; a developer 134 that visualizes the latent image formed on the photosensitive drum 131 as a toner image; and a toner output signal. And a writing scanning optical system comprising a laser light source (not shown) for recording a latent image on the photosensitive drum 131, a polygon mirror, and other mirrors.

  In addition, a primary transfer roller 135 is disposed at the upper portion of the print execution unit 130 for each color so as to face the photosensitive drum 131 so as to sandwich the intermediate transfer belt 136.

  The primary transfer roller 135 is, for example, an aluminum cored bar provided with a dielectric surface layer made of a predetermined resin, and is pressed against the photosensitive drum 131 via the ITB. Charges are supplied to the primary transfer roller 135 from a charge supply source (not shown), so that the surface potential of the primary transfer roller 135 is charged to a predetermined bias potential (for example, about +1 kV). ing.

  The intermediate transfer belt 136 is suspended on a plurality of belt conveyance rollers 137. For example, in the figure, there are provided a drive roller 137a, a backup roller 137c, and a tension roller 137d.

  A secondary transfer roller 138 is disposed at a position facing the drive roller 137a among the plurality of belt conveying rollers 137. In the vicinity of the tension roller arranged on the left side in the drawing, a belt cleaning blade 140 for collecting toner remaining without being transferred onto the intermediate transfer belt 136 is arranged. The tension roller 137d is opposed to the counter direction in the counter direction.

  Similar to the primary transfer roller 135, the secondary transfer roller 138 is, for example, an aluminum cored bar provided with a dielectric surface layer made of a predetermined resin, and is pressed against the drive roller 137a.

  The drive roller 137a and the secondary transfer roller 138 are brought into pressure contact with each other, and the toner image formed on the intermediate transfer belt 136, which is the first transfer material and the second image carrier, is used as the second transfer material. A second transfer unit configured to contact and transfer to a print sheet as an output medium is configured.

  When the toner image arrives at the second transfer site as the intermediate transfer belt 136 rotates, the printing paper as the second transfer material is supplied from the standard conveying system 107 to the second transfer unit in synchronism with this, and simultaneously shown in the drawing. A transfer bias is applied to the secondary transfer roller 138 by a charge supply source (for example, a transfer high-voltage power supply), and the toner image on the intermediate transfer belt 136 side is transferred to a second transfer material (output medium / printing paper). The

  For this reason, for example, similarly to the primary transfer roller 135, the secondary transfer roller 138 is supplied with a charge from a charge supply source (not shown), so that the surface potential of the secondary transfer roller 138 has a predetermined bias potential (for example, + About 1 kV).

  In addition, a voltage control unit for controlling the transfer output applied to each of the first transfer unit and the second transfer unit is provided, and the intermediate transfer belt 136 formed of an endless belt covers a predetermined range in the belt circumferential direction. Detecting the output current value during the constant voltage control by the voltage control unit, and determining the transfer output voltage to the first transfer unit or the second transfer unit controlled by the voltage control unit based on the detected output current value The transfer bias in the first transfer portion or the second transfer portion is controlled.

  Further, on the right side in the figure in the main unit 102, in order to discharge the printed recording paper fed from the secondary transfer roller 138 to the outside of the apparatus, the secondary transfer roller 138 is disposed downstream of the recording paper conveyance direction. For example, various conveying rollers such as a fixing roller 139 are provided.

  In the scanning output system 103 having such a configuration, first, the surface of the photosensitive drum 131 is negatively charged by the primary charger 133 with the same polarity as that of the toner, and becomes a V D potential. Thereafter, a yellow (Y) laser light source (not shown) as an exposure light source is driven by a yellow toner output signal (for example, an on / off binarization signal), thereby converting the yellow toner output signal into an optical signal. Then, the photosensitive drum 131 Y is irradiated with the converted laser light. As a result, the laser beam scans the photosensitive drum 131 Y charged by the primary charger 133 Y after being cleaned by the cleaner 132 Y, thereby forming an electrostatic latent image on the photosensitive drum 131 Y. . That is, the exposed portion on the photosensitive drum 131 that has been exposed to an image has a smaller absolute value of the potential and becomes a V L potential to form an electrostatic latent image.

  The electrostatic latent image is visualized as a toner image by the developing device 134 Y to which yellow toner is supplied. That is, a thin layer of toner is coated on a sleeve (not shown) rotatably attached to the developing device 134, and this toner is negatively charged. Since the sleeve is given a potential between the dark potential V D and the light potential V L of the photosensitive drum 131 by an external power source, the toner on the sleeve is transferred only to the portion of the light potential V L of the photosensitive drum 131. Thus, the electrostatic latent image is visualized.

  Thereafter, the photosensitive drum 131 Y and the primary transfer roller 135 Y form a pair, and the intermediate transfer belt 136 is nipped and conveyed, whereby the toner image is transferred to the intermediate transfer belt 136. That is, in the process of nipping and conveying the intermediate transfer belt 136, the intermediate transfer belt 136 is charged from the primary transfer roller 135 to the charged charge (negative charge in this example) of the photosensitive drum 131 (this example) The toner image on the photosensitive drum 131 is transferred and transferred to the intermediate transfer belt 136 as the first transfer material by the electric attraction, so that the intermediate transfer belt 136 is transferred to the second transfer belt 136. Function as an image carrier. After the transfer, excess toner is removed (cleaned) by the cleaner 132 from the photosensitive drum 131Y.

  Similarly, charging is performed by the primary chargers 133 M, 133 C, and 133 K based on the corresponding toner output signals of M, C, and K obtained sequentially at a constant interval with respect to the yellow toner output signal. By scanning the photosensitive drums 131 M, 131 C and 131 K, electrostatic latent images are sequentially formed on the photosensitive drums 131 M, 131 C and 131 K.

  Each electrostatic latent image is sequentially converted into a toner image by developing units 134 M, 134 C and 134 K to which toner of each color is supplied, and each toner image is intermediated by primary transfer rollers 135 M, 135 C and 135 K. Transfer is sequentially performed on the transfer belt 136. After transfer, excess toner is removed from the photosensitive drums 131 M, 131 C and 131 K by the cleaner 132.

  After this transfer, the portion of the intermediate transfer belt 136 where the image is transferred (transfer image portion) is conveyed in the direction of the secondary transfer roller 138. On the other hand, the standard transport system 107 transports the recording paper toward the contact portion between the drive roller 137a and the secondary transfer roller 138 by a pair of registration rollers. Then, the transfer image portion on the intermediate transfer belt 136 and the recording sheet are conveyed to the downstream side while being sandwiched by the secondary transfer roller 138, thereby printing the image on the recording sheet.

  The recording paper on which the toner images of Y, M, C, and K are sequentially multiplex-transferred in this way is peeled off from the intermediate transfer belt 136 and conveyed to a fixing unit 1 39 having a fixing roller for fixing. The toner image is fixed by heat on the recording paper by the toner image being fixed by the roller, and then discharged outside the machine such as a standard discharge tray. In addition, the primary transfer roller separation mechanism performs drive transmission from an intermediate transfer belt drive unit (not shown) by a separation drive connection unit 151.

  The separation driving unit performs a separation operation of the primary transfer roller according to a circumferential phase. FIG. 2 shows a state in which the primary transfer roller is all St apart.

  Similarly, FIG. 3 shows the position of the primary transfer roller 135K in the Bk single color output mode. During the Bk single color operation, only the primary transfer roller 135K is paired with the photosensitive member 131K, and the intermediate transfer belt 136 is nipped and conveyed. At this time, 135Y to 135C are in a state of being separated from the photosensitive drum 131.

  In addition, since the separation operation of the primary transfer roller 135 described above is performed in a circumferential phase as described above, it is driven only in one direction, and the separation operation according to this embodiment is a full color (installation for all stations). ) → All separation → Bk wearing (HP) → Full color (all station wearing)...

  Next, referring to the flowchart of FIG. 4, a stop sequence in the full color mode will be described. As described above, image formation is performed and print output is performed (S1). Next, if full color output is performed, after completion of image formation (S2 / S3), driving of the photosensitive drum and the intermediate transfer belt is stopped. FIG. 5 shows the state of the image forming apparatus according to this embodiment at this time. FIG. 6 shows a contact state between the cleaning blade 140 and the intermediate transfer belt 136.

  FIG. 6 shows a state where the cleaning blade 140 blocks each toner, and a lubricant such as toner exists between the cleaning blade 140 and the intermediate transfer belt 136 in the vicinity of the intermediate transfer belt 136. At this time, the cleaning blade 140 in the vicinity of the intermediate transfer belt is pulled in the driving direction of the intermediate transfer belt.

  Next, the drive is transmitted to a primary transfer roller separation drive (not shown), and the primary transfer rollers 135 of all the St are separated from the photosensitive drum 131 and the intermediate transfer belt 136. (S5) FIG. 7 shows the state of the image forming apparatus according to this embodiment at this time. FIG. 8 shows a contact state between the cleaning blade 140 and the intermediate transfer belt 136 at this time.

  When the primary transfer roller 135 is separated by all St, the intermediate transfer belt 136 is maintained in tension by the tension roller 137d. However, since the drive roller 137a is not driven, the position of 137d changes in order to maintain the tension. Thus, when viewed from the cleaning blade 140, the intermediate transfer belt 136 moves in the direction of the arrow, and rotates in the forward direction in the direction opposite to the driving direction or in the direction in which the cleaning blade 140 contacts.

  As a result, the lubricant present in the vicinity of the cleaning blade 140 and the intermediate transfer belt 136 moves upstream in the driving direction of the intermediate transfer belt 136 of the cleaning blade 140, and the cleaning blade 140 transfers the intermediate transfer belt. In the vicinity in contact with the belt 136, the tip of the cleaning blade 140 is driven by the intermediate transfer belt 136 and is not pulled into the intermediate transfer belt 136.

  Next, according to S6, only the primary transfer roller 135K of BkSt comes into contact with the photosensitive drum. FIG. 9 shows the state of the image forming apparatus according to the present embodiment at this time. FIG. 10 shows a contact state between the cleaning blade 140 and the intermediate transfer belt 136 at this time. Contrary to S5, since the primary transfer roller 135K of BkSt contacts only the photosensitive drum only with the primary transfer roller 135K, the intermediate transfer belt 136 moves in the driving direction of the intermediate transfer belt. However, since S6 is in contact only with the primary transfer roller 135K with respect to the movement amount of S5, the movement amount of the intermediate transfer belt is different and is smaller than S5.

  As a result, as shown in FIG. 10, the lubricant is positioned in the vicinity of the tip of the cleaning blade 140 at an amount higher in the driving direction of the intermediate transfer belt 136 than the point where the cleaning blade 140 and the intermediate transfer belt 136 are in contact with each other. The tip of the cleaning blade 140 is in a state of being pulled in the driving direction of the intermediate transfer belt.

  Next, in S7, the photosensitive drum 135K or 135 (Y to K) and the intermediate transfer belt 140 are rotated in reverse to bring the cleaning blade 140 and the intermediate transfer belt 136 into contact with each other as in FIG. (S8) When the image formation is in the BK single color mode, after the image formation, the photosensitive drum 135K and the intermediate transfer belt 136 are stopped (S9 / S10), and the process proceeds to S8.

  By this action, in the system in which the opposing roller of the cleaning blade 140 also serves as the tension roller 137d of the intermediate transfer belt, the intermediate transfer belt 136 is reversely rotated by the separation operation of the primary transfer roller 135 to cause the intermediate transfer belt 136 to reversely rotate. To prevent the cleaning blade 140 from chattering / turning over.

102 main unit, 103 scanning output system, 105 cartridge section,
107 Standard transport system

Claims (3)

A driving roller and a driven roller that is urged in a direction away from the driving roller by an urging means and reciprocates in the urging direction;
It is stretched over at least two blades, the blade facing roller and at least the driving roller and the blade facing roller, and is rotated and conveyed in a predetermined conveying direction.
The transfer belt and the blade-opposing roller are integrated with the blade-opposing roller, and reciprocate in the urging direction along with the blade-opposing roller.
A cleaner blade that cleans the surface of the transfer belt by bringing its tip into contact with the blade-opposing roller via the transfer belt;
Arranged in the transport direction downstream of the blade facing roller in the transport direction and upstream of the drive roller in the transport direction
A color image is formed by superimposing toner images of different colors that are arranged and primary transfer onto the surface of the transfer belt.
N image forming stations (N ≧ 2) and one-to-one for each of the N image forming stations inside the transfer belt
An image forming apparatus including N transfer members disposed opposite to each other with the transfer belt interposed therebetween,
The N transfer members are positioned on the image forming station side, and the transfer belt is moved to the image forming station by the N transfer members.
An image forming method for causing the image forming apparatus to execute an image forming operation by enabling the primary transfer of a toner image at all image forming stations by being pressed against each other, and is necessary after the image forming operation is performed. In accordance with the above, an image forming method characterized in that the following press releasing step and tension releasing step are executed. 2. The image forming apparatus according to claim 1, wherein, in the pressing release step and the tension releasing step, when the tension is released after the pressure is once released, the intermediate transfer belt rotates in the reverse conveyance direction. 3. . 2. The press release process and the tension release process, wherein when the tension release is performed after the pressure release is once performed, the intermediate transfer belt is rotated after the completion of image formation in the reverse conveyance direction. The image forming apparatus described in 1.