JP3671757B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to residual toner adhering to the photoreceptor in the image forming equipment for cleaning with a cleaning member, more particularly, it reduces the frictional resistance between the photosensitive member by applying toner to the new cleaning member after replacement It relates to an image forming equipment of that.
[0002]
[Prior art]
In an image forming apparatus such as a copying machine, a printer, or a facsimile using an electrophotographic system, a toner image formed on the surface of a photoreceptor is not completely transferred onto a transfer sheet, and untransferred toner remains. In order to perform the image forming operation continuously, it is necessary to completely remove and clean the residual toner by the cleaning member. As the cleaning member, a blade formed of an elastic body such as polyurethane is often used. In this configuration, the edge of the blade is brought into contact with the photoconductor to scrape off residual toner. However, in order to prevent cleaning failure due to edge wear, it is necessary to periodically replace the blade with a new blade (new cleaning member). .
[0003]
However, if the new blade and the cleaned photoconductor are in direct contact with each other, the frictional resistance is too great and the blade may be damaged. Therefore, an operator may apply setting powder to the blade or activate the developing means. In order to reduce the mutual frictional resistance, a new blade is brought into contact with the photosensitive member after the toner is attached to the photosensitive member to form a setting toner image.
[0004]
However, in the method in which the operator applies the setting powder to the blade, it is difficult to make the method of applying the powder uniform, unevenness occurs, and the same blade damage problem may occur at a place where the amount of powder is small.
[0005]
In the method of forming the setting toner image on the photoconductor, there is no problem of uneven powder amount, but when the setting toner image is scraped off with a new blade, the leading edge of the setting toner image is already downstream of the blade. To the position of the pre-charge exposure means, the charging means or the exposure means, etc., thus causing the problem that the toner is scattered and the pre-charge exposure means, the charge means or the exposure means is soiled. . That is, when a new blade is replaced and the new blade is first brought into contact with the photoconductor, if the setting toner image is not formed on the photoconductor, the photoconductor is directly rubbed and the new blade is damaged. Therefore, it is necessary to make the new blade contact with the setting toner image being formed, but for safety reasons, the tip of the setting toner image inevitably moves downstream from the blade contact position. The toner is scattered and contaminated on the pre-charging exposure means, charging means or exposure means downstream of the blade.
[0006]
[Problems to be solved by the invention]
It is an object of the present invention to provide an image in which the cleaning member is not damaged due to friction with the photosensitive member after replacement with a new cleaning member, and the toner adhered on the photosensitive member for setting does not scatter and stain the inside of the image forming apparatus. A forming apparatus and a novel cleaning member adjusting method are provided.
[0007]
[Means for Solving the Problems]
The above object of the present invention can be achieved by the following constitution.
[0008]
1. A photosensitive member that forms an electrostatic latent image; a driving unit that drives the photosensitive member; a developing unit that attaches toner to the electrostatic latent image formed on the photosensitive member to form a toner image; and In an image forming apparatus comprising: transfer means for transferring to transfer paper; and an exchangeable cleaning member that contacts the photoconductor and scrapes residual toner remaining on the photoconductor after transfer.
A load adjusting means for adjusting a contact load between the cleaning member and the photosensitive member;
Control means for controlling operations of the driving means, the developing means, and the load adjusting means;
The load adjusting means comprises a cam mechanism for adjusting the contact load by driving,
The control means activates the load adjusting means when the new cleaning member is brought into contact with the photosensitive member for the first time after the cleaning member is replaced with a new cleaning member, so that the contact load of the new cleaning member is set as a normal residual toner. The contact load when scraping off the toner is adjusted to be smaller, and the driving unit is operated to drive the photoconductor, and the developing unit is operated to attach toner to the photoconductor to form a setting toner image. An image forming apparatus controlled to form.
[0009]
2. When the leading edge of the setting toner image comes downstream from the contact position of the new cleaning member and the photosensitive member or the corresponding contact position, the control means operates the load adjusting means to move the new cleaning member. 2. The image forming apparatus according to 1 above, wherein the image forming apparatus is adjusted to a contact load when scraping off the residual toner, and drives the photosensitive member by operating the driving unit.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the image forming apparatus of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to this.
[0013]
1 is a schematic configuration diagram of a copying machine as an image forming apparatus, FIG. 2 is a schematic configuration diagram of an image forming unit of the copying machine, FIG. 3 is a front sectional view of a cleaning unit having a cleaning member, and FIG. FIG. 5 is a schematic view showing a part of the cleaning unit, and FIG. 6 is a timing chart for explaining a part of the operation of the image forming apparatus.
[0014]
In FIG. 1, the copying machine 101 stores transfer paper 105 inside the main body, and the transfer paper 105 used for the image forming operation is carried into the paper feeding unit 109 one by one by a paper feed roller 106 having a double feed prevention mechanism. . The sheet feeding unit 109 is disposed immediately before the image forming unit 1 and includes a loop roller 110 and a registration roller 111.
[0015]
On the other hand, in the image forming unit 1, the photosensitive drum 2 (photosensitive member) is rotated in the direction of arrow A by a driving unit to be described later, and a uniform potential is applied by the charging electrode 3. Digital data corresponding to a document (not shown) on the placement glass 113 is acquired and subjected to image processing. Based on the digital data subjected to this image processing, the surface of the photosensitive drum 2 on which the scanning exposure unit 114 is rotating is detected. Irradiate to form an electrostatic latent image corresponding to the original. Next, the electrostatic latent image is visualized by a developing unit 5 (developing means), and a toner image is developed on the surface of the photosensitive drum 2.
[0016]
The registration roller 111 is driven in synchronization with the rotation of the photosensitive drum 2, and the transfer paper 105 is sent to the transfer electrode 7 (transfer means). The transfer sheet 105 sent to the transfer electrode 7 is transferred with the toner image formed on the photosensitive drum 2, and then the transfer sheet 105 is separated from the photosensitive drum 2 by the separation electrode 8 and the separation claw 9. Then, the transport unit 117 transports to the fixing unit 118. A cleaning unit 11 disposed on the downstream side in the rotation direction of the photosensitive drum 2 with respect to the separation claw 9 cleans the surface of the photosensitive drum 2 after transfer to remove foreign matters, residual toner, and the like. When the residual toner is removed, the charging electrode 3 charges the surface of the photosensitive drum 2 again in preparation for the next image forming operation.
[0017]
The recycle pipe 6 conveys the residual toner collected by the cleaning unit 11 to the developing unit 5. The conveyed toner is used again for development. The developing unit 5 incorporates new toner supplied from a toner cartridge (not shown), and consumes new toner by executing an image forming operation. The collected toner is mixed into this new toner. In the present invention, the toner obtained by mixing the collected toner into the new toner is also referred to as a new toner.
[0018]
In the fixing unit 118, the transfer paper 105 is heated and pressurized to fix the toner image. In the case of single-sided copying, the transfer paper 105 is nipped by the transport roller 119 and sent to the paper discharge tray 123. In the case of double-sided copying, the transfer paper 105 on which the toner image has been fixed is sent to the stacker 120 through the evacuation conveyance path 121 by the conveyance roller 119 and temporarily evacuated. The transfer paper 105 temporarily retracted into the stacker 120 is sent out again and carried into the paper feeding unit 109 via the horizontal conveyance path 122, and the toner image is transferred and fixed again.
[0019]
Next, details of the image forming unit 1 will be described with reference to FIG. The image forming unit 1 of the copying machine 101 includes a charging electrode 3 (charging unit), a scanning exposure unit 114 (exposure unit), a developing unit 5 (developing unit), around a photosensitive drum 2 (photosensitive unit). A transfer electrode 7 (transfer means), a separation electrode 8, a separation claw 9, a cleaning unit 11, and a pre-charge exposure unit (PCL) 12 (pre-charge exposure means) are sequentially arranged. These are connected to the control means 13 built in the copying machine 101. The control unit 13 operates the developing unit, a driving unit or a load adjusting unit, which will be described later, based on information input by the user from an instruction input unit (not shown), and executes overall sequence control of the copier 101. .
[0020]
In the image forming unit 1, the surface of the photosensitive drum 2 is given a uniform + charge by the action of the charging electrode 3, and then the photosensitive drum on which the scanning exposure unit 114 is rotating based on the digital data subjected to image processing. 2 is irradiated to form an electrostatic latent image. The toner is agitated inside the developing unit 5, and the toner is positively charged due to mutual friction. The developing unit 5 includes a sleeve 5 a having a rotation axis parallel to the rotation axis of the photosensitive drum 2. When a developing bias is applied to the sleeve 5 a, the electrostatic latent image is a positively charged toner in the developing unit 5. Is developed (reversal development), and a toner image is formed on the surface of the photosensitive drum 2.
[0021]
When the transfer paper 105 is fed in synchronization with the rotation of the photosensitive drum 2, the transfer electrode 7 imparts a charge to the back surface of the transfer paper 105, and the toner image on the surface of the photosensitive drum 2 is transferred to the transfer paper 105. Transcribed. The transfer paper 105 to which the toner image has been transferred is neutralized by the discharge of the separation electrode 8, and the adsorption force with the photosensitive drum 2 is reduced. And sent to the fixing unit 118.
[0022]
On the other hand, toner that is not transferred remains on the photosensitive drum 2 that passes through the separation claw 9, but the residual toner is collected by the cleaning unit 11, and the photosensitive drum 2 that has been cleaned by the pre-charge exposure unit 12 is uniformly distributed. Exposure to light makes the residual potential erased and uniform, and prepares for the next charging.
[0023]
The recycle pipe 6 is a pipe-like member having a screw for conveying toner inside, and connects the cleaning unit 11 to the developing unit 5, and is removed from the surface of the photosensitive drum 2 and collected by the cleaning unit 11. Toner is fed into the developing unit 5. The toner sent to the developing unit 5 by the recycle pipe 6 is used again for development.
[0024]
The drum drive motor 40 (drive means) starts and stops rotation according to the control of the control means 13. When the toner image is developed on the photosensitive drum from the image information read from the original, or when the blade in the cleaning unit 11 is replaced with a new blade, the toner is applied to the photosensitive drum 2 for the first time. The photosensitive drum 2 is rotated by the drum drive motor 40 when a setting toner image is formed by adhesion and the setting toner image is scraped off by a blade.
[0025]
Next, the configuration of the cleaning unit 11 will be described in detail with reference to FIGS.
[0026]
3 is a front sectional view of the cleaning unit 11, and FIG. 4 is a sectional view showing a IV-IV section of FIG.
[0027]
The cleaning unit 11 includes a housing 14, a brush roller 16, a toner transport unit 17, and a blade 18 that is a cleaning member. The cleaning unit 11 presses and contacts (contacts) the blade 18 with the surface of the photosensitive drum 2 to remove residual toner. The residual toner that has been scraped off and then scraped off once rides on the brush roller 16 and falls into the screw 17a of the toner conveying means 17. The screw 17a is rotated by a driving mechanism (not shown) to collect the dropped toner, and the collected toner is sent again to the developing unit 5 through the recycling pipe 6 and accumulated in the developing unit 5. The toner is mixed in the toner and stirred together, and then reused for image formation.
[0028]
The blade 18 is sandwiched and fixed by a blade holder 18 a constituted by two L-shaped metal fittings in cross section, and the blade holder 18 a is fixed to two holder side plates 22 a of the holder main body 22. The holder main body 22 has a holder top plate 22b and a holder back plate 22c that are continuous with the holder side plate 22a, and rotating shafts 23 project from both sides of the holder top plate 22b. Since the rotation shaft 23 is rotatably supported by the both side plates 14a of the housing 14, the holder main body 22 can be rotated in two directions as indicated by an arrow C shown in FIG.
[0029]
A weight plate 24 is engaged with the holder back plate 22c. The weight plate 24 gives a rotational moment about the rotation shaft 23 to the holder main body 22 and the blade 18 so that the tip of the blade 18 is exposed. Adjustment is made so as to contact the surface of the body drum 2 with a constant pressure.
[0030]
One end of the rotating shaft 23 passes through the side plate 14a and is connected to a cam mechanism 25 serving as load adjusting means. The cam mechanism 25 is fixed to an end of the rotation shaft 23 and constitutes a follower, a cam 27 that moves the arm 26 up and down to rotate the rotation shaft 23, and a shaft 27a. A driven gear 28 that transmits a rotational force to the cam 27, a drive gear 30 that is connected to the driven gear 28 via an idle gear 29, and a cam drive motor 31 that transmits a rotational force in a predetermined direction to the drive gear 30 are provided. ing. The cam drive motor 31 drives the cam mechanism 25 under the control of the control means 13, and the pressure (contact load) at the time of contact between the blade 18 and the photosensitive drum 2 depending on the degree that the cam 27 pushes up the arm 26. Is determined. Note that the bending degree of the blade 18 changes if the contact load changes, but the bending of the blade 18 is omitted in FIGS. 3 and 4.
[0031]
Next, adjustment of the contact load by the cam mechanism 25 will be described with reference to FIG.
[0032]
FIG. 5 is a schematic diagram showing a part of the cleaning unit 11, and FIGS. 5A and 5B show a state in which the contact load applied to the photosensitive drum 2 and the blade 18 is different.
[0033]
As preparation for executing image formation, the cam drive motor 31 supplies drive based on the control of the control means 13 to rotate the cam 27, and the arm 26 and the cam 27 are not contacted as shown in FIG. Put it in a state. When the arm 26 and the cam 27 are not in contact with each other, the weight of the weight plate 24 is applied to the holder main body 22, so the holder main body 22 approaches the photosensitive drum 2 around the rotation shaft 23 (arrow B 1). The blade 18 and the photosensitive drum 2 are pressure-bonded (contacted). The contact load between the blade 18 and the photosensitive drum 2 thus pressure-bonded is usually a contact load (hereinafter referred to as a cleaning load) when scraping off residual toner. The cleaning load is an optimum contact load that removes residual toner adhering to the photosensitive drum 2 and does not interfere with the next image forming operation. When the cleaning load is applied, the control unit 13 executes sequence control relating to an image forming operation for forming a normal toner image.
[0034]
Next, the case where the new blade is brought into contact with the photosensitive member for the first time after replacing the blade (cleaning member) with a new blade (new cleaning member) will be described.
[0035]
Before describing the blade replacement, in order to replace the blade 18 with the new blade 18, the blade 18 is completely detached from the photosensitive drum 2 (with the contact state released), the blade is removed, and the new blade 18 is removed. Install the blade. The blade may be replaced manually by an operator. For example, as in the invention disclosed in Japanese Patent Laid-Open No. 6-95448, a new blade for replacement is built in the cleaning unit and automatically replaced with a new blade. The rotation may be exchanged. For convenience of explanation, the blade before replacement was called “blade”, and the blade after replacement was called “new blade”. However, in the drawing, only the time before or after blade replacement is different. Is also indicated by 18. FIG. 5B shows the state of the contact load when the cleaning unit of FIG. 5 contacts the photosensitive drum 2 for the first time after replacement with a new blade 18 of a type in which the blade is manually replaced. The cam drive motor 31 supplies drive to rotate the cam 27, and the cam 27 rotates to push up the arm 26 against the load applied by the weight plate 24. Corresponding to the rotation of the arm 26, the holder main body 22 rotates in a direction (arrow B2) that is dissociated from the photosensitive drum 2. The rotation of the cam drive motor 31 is set to stop within a range in which the contact between the blade 18 and the photosensitive drum 2 is maintained. At this time, although the blade 18 is pressure-bonded to the photosensitive drum 2, the contact load with the photosensitive drum 2 is smaller than the contact load when scraping off the residual toner (hereinafter referred to as setting load). ) Is adjusted. The blade 18 is not damaged even when the photosensitive drum 2 is directly applied to the blade 18 with the setting load applied to the blade 18 and rotated, but the tip of the blade 18 is in contact with the photosensitive drum 2. Therefore, the toner image developed on the photoreceptor can be scraped off.
[0036]
By operating the cam mechanism 25 as the load adjusting means, the contact load between the blade 18 and the photosensitive drum 2 is changed into a cleaning load (FIG. 5A) and a setting load (FIG. 5B). Can be switched between.
[0037]
Next, the control by the control means when the cleaning member is brought into contact with the photosensitive member for the first time after replacement with a new cleaning member will be described with reference to FIG.
[0038]
FIG. 6 is a timing chart for explaining the operation after replacement of the cleaning member of the image forming apparatus of the present invention. The passage of time is the order from (1) to (9).
[0039]
First, the blade is replaced with a new blade 18 in the state where the contact load of the blade is released before {circle around (1)}. When the replacement is completed, in (1), a setting load is applied to the new blade 18, and the new blade 18 comes into contact with the photosensitive drum 2 so that the new blade 18 is not damaged (setting load adjusting step). The time point {circle around (1)} is when the cleaning member comes into contact with the photosensitive member for the first time after replacement with a new cleaning member. When the photosensitive drum 2 is rotated in this state, a setting toner image described below is scraped off by the new blade 18 (not completely removed).
[0040]
Next, in (2), the photosensitive drum 2 starts to rotate by the driving means. At the same time, the pre-charge exposure unit (PCL) 12 starts to operate, and the residual potential is erased and made uniform. Similarly, at the time of (2), the developing unit 5 starts to operate. When the rotational speed of the photosensitive drum 2 reaches a constant value (3), a developing bias is started, toner is attached to the photosensitive member, and a setting toner image is developed (setting toner image forming step). In this embodiment, development is performed in a state where only the developing bias is ON without operating the charging electrode 3, so that the setting toner image has a uniform halftone on the surface of the photosensitive drum 2. The toner image for setting serves as a so-called setting powder for preventing friction when the new blade 18 is brought into contact with the photosensitive drum 2 for the first time. The contact load of the new blade is used as a cleaning load. There is no particular limitation on the pattern and density of the toner image, as long as the photosensitive drum 2 and the blade 18 are frictioned at the time of switching, and the friction can be reduced to the extent that the new blade 18 is not damaged. The toner image may be the same as that formed by reading a document at the time of normal image formation. However, for setting purposes, a uniform halftone is preferable on the entire surface of the photosensitive drum 2.
[0041]
Next, in (4), the driving of the photosensitive drum 2 is stopped and the rotation of the photosensitive drum 2 is decelerated. At the same time, the developing bias is turned off, and the setting toner image formation is completed. When the rotation of the photosensitive drum 2 is completely stopped, the driving of the PCL 12 and the developing unit 5 is turned off.
[0042]
Next, in (6), the blade contact load is switched to the cleaning load (cleaning load adjustment step). At this time, the timing is such that the setting toner image is present at the contact position between the new blade 18 and the photosensitive drum 2. In other words, the leading edge of the setting toner image (the portion first developed with the toner attached) comes to at least the position where the new blade 18 and the photosensitive drum 2 are in contact or downstream (PCL 12 side). Must be. This is to avoid friction between the new blade 18 and the photosensitive drum 2 as described above.
[0043]
Next, in (7), when the photosensitive drum 2, the PCL 12 and the developing unit 5 start to operate, a new blade to which a cleaning load is applied is scraped off and removed from the setting toner image. Setting (adjustment) can be performed so that toner adheres to the edge of the new blade and does not cause damage or damage due to friction with the photosensitive drum 2 (cleaning step). In (8), after all setting toner images have been removed, the photosensitive drum 2 stops rotating, the PCL 12 and the developing unit 5 are turned off, and the blade contact load is switched to the setting load for setting (adjustment). ) Ends ((9)). In this embodiment, the blade contact load is switched to the setting load at the end of the setting, but the cleaning load may be held as it is. The control unit 13 performs the above timing control.
[0044]
According to the present invention, the timing for switching the contact load between the new blade 18 and the photosensitive drum 2 from the setting load to the cleaning load does not need to be controlled with high accuracy, which is advantageous in terms of technology and cost. That is, in the case of an image forming apparatus that has an automatic blade replacement mechanism as in the invention disclosed in JP-A-6-95448 and forms a toner image for setting, the contact load is canceled and the cleaning load is switched. However, if the timing of switching is too early, damage due to friction of the new blade is caused, and if it is too late, there is a problem that contamination in the image forming apparatus due to toner scattering occurs, but the image forming apparatus and the cleaning member of the present invention It was solved by the adjustment method. That is, switching can be performed with a sufficient margin to avoid friction between the new blade 18 and the photosensitive drum 2. Even if the leading edge of the setting toner image reaches the PCL 12, the charging electrode 3, and the scanning exposure unit 114, the new blade 18 and the photosensitive drum 2 are in contact with each other with a setting load from the beginning. Is scraping off excessive toner on the surface by the new blade 18 (not completely removed), and can prevent contamination in the image forming apparatus due to toner scattering.
[0045]
In this embodiment, the case of a digital copying machine has been described. However, the present invention is not limited to this, and can be applied to an analog copying machine, a laser printer, a digital facsimile apparatus, and an image forming apparatus that outputs a color image.
[0046]
Further, the present invention can be applied to an image forming apparatus that uses a toner image on a belt-like photoreceptor instead of the photoreceptor drum.
[0047]
Further, although an example in which + charge is applied to the toner and the photosensitive drum 2 has been described, the present invention can also be applied to an image forming apparatus that applies −charge.
[0048]
【The invention's effect】
After replacing a new cleaning member, there is no damage to the cleaning member due to friction with the photosensitive member, and scattered toner deposited on the photosensitive member for setting an image forming equipment without contaminating the inside of the image forming apparatus I was able to.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a copier as an image forming apparatus.
FIG. 2 is a schematic configuration diagram of an image forming unit of a copying machine.
FIG. 3 is a front sectional view of the cleaning unit.
4 is a cross-sectional view showing a cross section taken along line IV-IV in FIG. 3;
FIG. 5 is a schematic diagram showing a part of a cleaning unit.
FIG. 6 is a timing chart illustrating an operation after replacement of the cleaning member of the image forming apparatus of the present invention.
[Explanation of symbols]
2 Photosensitive drum 5 Development unit 6 Recycle pipe 11 Cleaning unit 13 Control means 18 Blade 25 Cam mechanism 26 Arm 27 Cam 31 Cam drive motor 40 Drum drive motor 101 Copying machine 105 Transfer paper

Claims (2)

A photosensitive member that forms an electrostatic latent image; a driving unit that drives the photosensitive member; a developing unit that attaches toner to the electrostatic latent image formed on the photosensitive member to form a toner image; and In an image forming apparatus comprising: transfer means for transferring to transfer paper; and an exchangeable cleaning member that contacts the photoconductor and scrapes residual toner remaining on the photoconductor after transfer.
A load adjusting means for adjusting a contact load between the cleaning member and the photosensitive member;
Control means for controlling operations of the driving means, the developing means, and the load adjusting means;
The load adjusting means comprises a cam mechanism for adjusting the contact load by driving,
The control means activates the load adjusting means when the new cleaning member is brought into contact with the photosensitive member for the first time after the cleaning member is replaced with a new cleaning member, so that the contact load of the new cleaning member is set as a normal residual toner. The contact load when scraping off the toner is adjusted to be smaller, and the driving unit is operated to drive the photoconductor, and the developing unit is operated to attach toner to the photoconductor to form a setting toner image. An image forming apparatus controlled to form.   When the leading edge of the setting toner image comes downstream of the contact position between the new cleaning member and the photosensitive member or the corresponding contact position, the control means operates the load adjusting means to move the new cleaning member. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus adjusts the contact load when scraping off the residual toner, and drives the photosensitive member by operating the driving unit.

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