JP2007004079A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which toner is prevented from slipping through a cleaning blade by uniformizing the worn state of the cleaning blade without causing partial wear in order to prevent nonuniform deterioration of the cleaning blade and to extend the lifetime of a cleaning device. <P>SOLUTION: In the image forming apparatus which has a transfer member onto which a toner image on an image carrier is transferred, and in which a toner mark is transferred onto the transfer member, and according to signals obtained by reading the transferred toner mark through a reading means, control and correction for image formation are performed, the width of the transfer mark is made variable in a rotation direction of the transfer member at the transfer position of the toner mark on the transfer member every time an image is formed, so that nonuniform deterioration of the cleaning blade can be prevented without increasing toner consumption. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to marking of a toner mark that maintains the quality of a cleaning device over time without adding new parts to an intermediate transfer member cleaning device.

Conventionally, when a toner mark is transferred to an intermediate transfer member for the purpose of detecting a belt position or correcting a color misregistration amount in an image forming apparatus, the toner mark is intermittently transferred to a specific part (Patent Document 1). .
JP 2003-186278 A

  However, in the technique as described above, when the toner mark is cleaned, there is a problem that the cleaning blade deteriorates only partly due to the influence of the input toner and the quality of the cleaning device is lowered. In addition, the occurrence of a specific portion of wear, as indicated by the solid line in FIG. 5, causes a drop in quality such as toner passing through the cleaning blade or turning the blade.

  The present invention has been made in view of such circumstances, and prevents uneven cleaning of the cleaning blade and improves the life of the apparatus. As shown by the dotted line in FIG. An object of the present invention is to prevent the toner from slipping out by leveling the wear state instead of only a part of the wear.

  According to the first aspect of the present invention, there is provided a transfer body for transferring a toner image of an image carrier, a toner mark is transferred to the transfer body, and the transferred toner mark is read from a reading means by a signal obtained. In the image forming apparatus that performs control and correction for image formation, the width of the toner mark is changed in the rotation direction of the transfer body at the transfer position of the toner mark on the transfer body every time an image is formed. An image forming apparatus that performs control and correction.

  According to a second aspect of the present invention, there is provided a transfer body for transferring a toner image of an image forming apparatus capable of outputting an image of two or more colors, a toner mark is transferred to the transfer body, and the transferred toner mark is read. In an image forming apparatus that performs control and correction for image formation based on a signal obtained by reading from the means, the width of the toner mark is changed for each color, and a toner image having substantially the same shape is transferred for each color. An image forming apparatus characterized by the above.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, when the toner mark is transferred at an interval, the position of the toner mark can be varied in the axial direction.

  According to a fourth aspect of the present invention, there is provided a transfer body for transferring a toner image of an image forming apparatus capable of outputting an image of two or more colors, a toner mark is transferred to the transfer body, and the transferred toner mark is read. In an image forming apparatus that performs control and correction for image formation based on signals obtained by reading from the means, the position of the toner mark is changed for each color, and the toner image is transferred to the same position for each color. An image forming apparatus.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the image forming apparatus includes a device capable of moving a position of a sensor that reads a toner mark on the transfer body in an axial direction of the transfer body. It is characterized by.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the average circularity of the toner used is 0.90 to 0.99.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the shape factor SF-1 of the toner to be used is 120 to 180, and the shape factor SF-2 is 120. ˜190.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, when Dv of the toner to be used is a volume average particle diameter μm and Dn is a number average particle diameter μm, Dv / Dn is 1.05-1.30.

  According to the present invention, it is possible to prevent deterioration of only a specific part of the cleaning blade, and to maintain the quality of the blade even in the aging state. Further, by changing the width and position for each color, it is possible to minimize the variation in reading the toner marks of the respective colors.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the present exemplary embodiment, an electrophotographic color laser printer (hereinafter referred to as “laser printer”) is used as an example of an image forming apparatus.

  FIG. 1 is a schematic configuration diagram of a laser printer according to the present embodiment. This laser printer includes four toner image forming units 1Y, 1M, 1C, 1K (hereinafter referred to as “yellow” (Y), magenta (M), cyan (C), and black (K)). The subscripts Y, M, C, and K of the reference numerals indicate yellow, magenta, cyan, and black members, respectively, and the direction of movement of the transfer paper 100 (the belt 60 along the arrow A in the figure). In the traveling direction) from the upstream side. Each of the toner image forming units 1Y, 1M, 1C, and 1K includes photosensitive drums 11Y, 11M, 11C, and 11K as image carriers and a developing unit. The arrangement of the toner image forming units 1Y, 1M, 1C, and 1K is set so that the rotation axes of the photosensitive drums are parallel to each other and arranged at a predetermined pitch in the transfer paper moving direction.

  In addition to the toner image forming units 1Y, 1M, 1C, and 1K, the laser printer carries the optical writing unit 2, the paper feed cassettes 3 and 4, the registration roller pair 5, and the transfer paper 100, and each toner image forming unit. A transfer unit 6 as a belt driving device having a transfer conveyance belt 60 as a transfer conveyance member that conveys the sheet so as to pass through the transfer position, a belt fixing type fixing unit 7, a paper discharge tray 8, and the like. In addition, a manual feed tray MF and a toner supply container TC are provided, and a waste toner bottle, a duplex / reversing unit, a power supply unit, and the like (not shown) are also provided in a space S indicated by a two-dot chain line.

  The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photosensitive drums 11Y, 11M, 11C, and 11K while scanning the laser beam based on the image data. To do.

FIG. 2 is an enlarged view showing a schematic configuration of the transfer unit 6. The transfer conveyance belt 60 used in the transfer unit 6 is a high-resistance endless single-layer belt having a volume resistivity of 10 ⁹ to 10 ¹¹ Ωcm, and the material thereof is PVDF (polyvinylidene fluoride). The transfer conveyance belt 60 is wound around support rollers 61 to 68 so as to pass through the transfer positions that are in contact with and face the photosensitive drums 11Y, 11M, 11C, and 11K of the toner image forming units.

  Among these support rollers, the entrance roller 61 on the upstream side in the transfer sheet moving direction is disposed on the outer peripheral surface of the transfer conveyance belt 60 so that the electrostatic adsorption roller 80 to which a predetermined voltage is applied from the power source 80a is opposed. Yes. The transfer paper 100 that has passed between the two rollers 61 and 65 is electrostatically attracted onto the transfer conveyance belt 60.

  A roller 63 is a drive roller that frictionally drives the transfer conveyance belt 60, and is connected to a drive source (not shown) and rotates in the direction of the arrow. As a transfer electric field forming means for forming a transfer electric field at each transfer position, transfer bias applying members 67Y, 67M, 67C, and 67K are provided at positions facing the photosensitive drum so as to be in contact with the back surface of the transfer conveyance belt 60. ing. These are bias rollers provided with a sponge or the like on the outer periphery, and a transfer bias is applied to the roller core from each transfer bias power source 9Y, 9M, 9C, 9K. Due to the action of the applied transfer bias, a transfer charge is applied to the transfer conveyance belt 60, and a transfer electric field having a predetermined strength is formed between the transfer conveyance belt 60 and the surface of the photosensitive drum at each transfer position. In addition, a backup roller 68 is provided to keep the contact between the transfer paper and the photoconductor in the area where the transfer is performed, and to obtain the best transfer nip.

  The transfer bias applying members 67Y, 67M, and 67C and the backup roller 68 disposed in the vicinity thereof are integrally held by the swing bracket 93 so as to be rotatable, and can be rotated around a rotation shaft 94. This rotation is clockwise when the cam 96 fixed to the cam shaft 97 is rotated in the direction of the arrow.

  The entrance roller 61 and the suction roller 80 are integrally supported by the entrance roller bracket 90, and can be rotated clockwise from the state shown in FIG. A hole 95 provided in the swing bracket 93 and a pin 92 fixed to the entrance roller bracket 90 are engaged with each other, and rotate in conjunction with the rotation of the swing bracket 93. By the clockwise rotation of these brackets 90, 93, the bias applying members 67Y, 67M, 67C and the backup roller 68 disposed in the vicinity thereof are separated from the photoreceptors 11Y, 11M, 11C, and the entrance roller 61 and the suction roller 80 also moves downward. It is possible to avoid contact between the photoconductors 11Y, 11M, and 11C and the transfer conveyance belt 60 when forming a black-only image.

  On the other hand, the transfer bias applying member 67K and the backup roller 68 adjacent to the transfer bias applying member 67K are rotatably supported by the outlet bracket 98, and are rotatable about a shaft 99 coaxial with the outlet roller 62. When attaching / detaching the transfer unit 6 to / from the main body, the transfer unit 6K is rotated clockwise by operating a handle (not shown), and the transfer bias applying member 67K and the backup roller 68 adjacent thereto are moved from the black image forming photosensitive member 11K. They are separated.

  As shown in FIG. 1, a cleaning device 85 including a brush roller and a cleaning blade is disposed on the outer peripheral surface of the transfer conveyance belt 60 wound around the driving roller 63. The cleaning device 85 removes foreign matters such as toner adhering to the transfer conveyance belt 60.

  A roller 64 is provided downstream of the driving roller 63 in the traveling direction of the transfer conveyance belt 60 in a direction to push the outer peripheral surface of the transfer conveyance belt, and a winding angle around the drive roller 83 is ensured. A tension roller 65 for applying tension to the belt by a pressing member (spring) 69 (see FIG. 1) is provided in the loop of the transfer conveyance belt 60 further downstream from the roller 64.

  The one-dot chain line in FIG. 1 shown above indicates the conveyance path of the transfer paper 100. The transfer paper 100 fed from the paper feed cassettes 3 and 4 or the manual feed tray MF is transported by transport rollers while being guided by a transport guide (not shown), and is transported to a temporary stop position where the registration roller pair 5 is provided. The transfer paper 100 delivered at a predetermined timing by the registration roller pair 5 is carried on the transfer conveyance belt 60, conveyed toward the toner image forming units 1Y, 1M, 1C, and 1K, and passes through the transfer nips. .

  The toner images developed on the toner drums 11Y, 11M, 11C, and 11K of the toner image forming units 1Y, 1M, 1C, and 1K are superimposed on the transfer paper 100 at the transfer nips, respectively. It is transferred onto the transfer paper 100 under the action of pressure. By this superposition transfer, a full-color toner image is formed on the transfer paper 100.

  The surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K after the toner image transfer are cleaned by a cleaning device, and are further discharged to prepare for the formation of the next electrostatic latent image.

  On the other hand, after the full-color toner image is fixed by the fixing unit 7, the transfer paper 100 on which the full-color toner image is formed corresponds to the rotation posture of the switching guide G (see FIG. 1) and the first paper discharge. The direction is B or the second paper discharge direction C. When the paper is discharged from the first paper discharge direction B onto the paper discharge tray 8, it is stacked in a so-called face-down state with the image surface down. On the other hand, when the paper is discharged in the second paper discharge direction C, it is conveyed toward another post-processing device (such as a sorter or a binding device) (not shown), or is registered again for double-sided printing via a switchback unit. It is conveyed to the roller pair 5.

  FIG. 4 shows a mark transfer state on the intermediate transfer belt, which is a feature of this embodiment. The toner mark transferred onto FIG. 3 is scraped by the cleaning device 85 of FIG. For example, after the toner mark A in FIG. 3 is transferred five times, the toner mark A ′ is transferred once, and the repetition of this mark prevents the cleaning blade from partially deteriorating. FIG. 3 is a diagram showing an example in which the shape and position of the toner mark according to the embodiment of the present invention are changed so as to be on the reading position of the sensor. FIG. 3A shows the width of the toner mark changed. An example is shown, (b) shows an example in which the position of the toner mark is changed without changing the size of the toner mark so that the toner mark exists within the reading position of the sensor, and (c) shows a toner mark by changing the reading position of the sensor. It is explanatory drawing which shows the example which made it detect.

  By sequentially changing the toner mark form to the toner marks A to C, it is possible to prevent the cleaning blade from being deteriorated unevenly. The state of wear of the cleaning blade at this time is shown in FIG. If the sensor that reads the toner mark is placed on a device that is driven horizontally by a motor and a gear train, and the toner mark can be read by controlling the position of the sensor, the toner mark input position can be changed to change the toner mark. Non-uniform degradation of the blade can be prevented without increasing consumption.

  In the above embodiment, in the tandem printer in which the photosensitive drums 11Y, 11M, 11C, and 11K are arranged side by side on the transfer conveyance belt 60, the transfer electric field is superimposed on the transfer paper 100 at each transfer nip. Although the present invention is applied to the transfer unit 6 that is transferred onto the transfer paper 100 under the action of the nip pressure, a printer and a belt driving device to which the present invention can be applied are not limited to this configuration. In a transfer body in which an endless belt stretched around a plurality of rollers is rotationally driven by at least one of the rollers, a toner mark is transferred onto the transfer body, and finally the toner mark is removed by a cleaning device. Any image forming apparatus having a cleaning process can be applied.

In the present invention, FIG. 6A is a diagram schematically showing the shape of the toner for explaining the shape factor SF-1 and FIG. 6B is a diagram for explaining the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) 2 / AREA} * (100 [pi] / 4) .. Formula (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) 2 / AREA} × (100π / 4) .. Formula (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

  Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.

  When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a transfer unit according to an embodiment of the present invention. It is a figure which shows the example which changed the shape and position of the toner mark which concern on embodiment of this invention so that it may exist on the reading position of a sensor. FIG. 4 is a plan view of a toner mark on a transfer body according to an embodiment of the present invention. It is a schematic diagram for demonstrating the abrasion state of the cleaning blade which concerns on embodiment of this invention, and the abrasion state in a prior art. FIG. 3 is a diagram schematically illustrating a toner shape for explaining a shape factor according to an embodiment of the present invention.

Explanation of symbols

1Y, 1M, 1C, 1K Toner image forming unit 2 Optical writing unit 3, 4 Paper feed cassette 5 Registration roller pair 6 Transfer unit 7 Fixing unit 8 Paper discharge tray 9 Transfer bias power supply 9Y, 9M, 9C, 9K Transfer bias power supply 10 Photosensitive unit 11Y, 11M, 11C, 11K Photosensitive drum 60 Transfer conveyance belt 61-68 Support roller 67Y, 67M, 67C, 67K Transfer bias applying member 80 Electrostatic adsorption roller 80a Power supply 90 Entrance roller bracket 91 Shaft 92 Pin 93 Swing Moving bracket 94 Rotating shaft 95 Hole 96 Cam 97 Cam shaft 98 Exit bracket 99 Axis 100 Transfer paper 101 Toner mark A Belt running direction B First paper discharge direction C Second paper discharge direction S Space MF Manual feed tray G Switching guide

Claims (8)

A transfer member for transferring a toner image on the image carrier, transferring a toner mark to the transfer member, and reading the transferred toner mark from a reading unit; In an image forming apparatus that performs correction,
2. An image forming apparatus according to claim 1, wherein each time an image is formed, the width and width of the toner mark are changed in the rotation direction of the transfer body at the transfer position of the toner mark on the transfer body to perform the control and correction. A signal obtained by transferring a toner image of an image forming apparatus capable of outputting an image of two or more colors, transferring a toner mark to the transfer member, and reading the transferred toner mark from a reading unit In the image forming apparatus that performs control and correction for image formation,
An image forming apparatus, wherein a width of the toner mark is changed for each color, and a toner image having substantially the same shape is transferred for each color.   2. The image forming apparatus according to claim 1, wherein the position of the toner mark can be varied in the axial direction when the toner mark is transferred at intervals. A signal obtained by transferring a toner image of an image forming apparatus capable of outputting an image of two or more colors, transferring a toner mark to the transfer member, and reading the transferred toner mark from a reading unit In the image forming apparatus that performs control and correction for image formation,
An image forming apparatus, wherein a position of the toner mark is changed for each color, and a toner image is transferred to the same position for each color.   5. The image forming apparatus according to claim 3, further comprising a device capable of moving a position of a sensor for reading a toner mark on the transfer body in an axial direction of the transfer body.   5. The image forming apparatus according to claim 1, wherein the toner used has an average circularity of 0.90 to 0.99. 6.   The image forming apparatus according to any one of claims 1 to 4, wherein the toner has a shape factor SF-1 of 120 to 180 and a shape factor SF-2 of 120 to 190.   5. The toner according to claim 1, wherein Dv / Dn is 1.05 to 1.30, where Dv is a volume average particle diameter μm and Dn is a number average particle diameter μm. 2. The image forming apparatus according to item 1.

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