JP2006184454A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove an adhesive matter at required time by required amount with simple constitution and to always obtain image quality in an excellent state with absolute minimum time and toner consumption. <P>SOLUTION: The tandem image forming apparatus 1 is equipped with an adhesive matter removing mode for performing cleaning operation for photoreceptors 101 to 104 and an intermediate transfer body 501 except for the time when an image is formed. In the adhesive matter removing mode, a toner image remaining on the photoreceptors 101 to 104 without being transferred to the intermediate transfer body 501 is removed by photoreceptor cleaning means 301 and 304, and also the toner image transferred to the intermediate transfer body 501 is removed by an intermediate transfer body cleaning means 520. The adhesive matter removing mode is simultaneously performed to the photoreceptors 101 to 104 and the intermediate transfer body 501. Thus, the time required to make the adhesive matter removing mode act is made shorter as compared with the case that the adhesive matter removing mode is applied separately to them. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a fax machine using an electrophotographic technique, and more particularly to a technique for removing deposits in the image forming apparatus.

Currently, there is an image forming apparatus that employs an intermediate transfer system that primarily transfers a toner image formed on an image bearing member to an intermediate transfer member and secondarily transfers the toner image on the intermediate transfer member to a transfer material. It has been. In such an image forming apparatus, the image carrier and the intermediate transfer member are in contact with each other for primary transfer, but in addition to these, transfer materials such as paper, rollers, etc. In most cases, the rubber member or the like used in the above is in direct or indirect contact.
There are various types of paper, but the types of fiber parts used as raw materials and additives to be added are also diverse. As a failure example caused by paper for the image forming apparatus, there is a problem due to paper dust generated by friction with a rubber roller or the like when the paper is transported in the apparatus. In particular, the talc contained in the paper is an image carrier. Further, there are known problems that adhesion to the surface of an intermediate transfer member causes a change in surface property and surface resistance state, thereby disturbing an image and deterioration of the surface property of an image bearing member or an intermediate transfer member. In addition, as a failure example caused by the rubber member that contacts the image carrier and the intermediate transfer member, the component contained in the rubber rarely oozes out, contaminating the surface of the image carrier and the intermediate transfer member, The image may be disturbed or the surface quality may be deteriorated.

  As a prior art related to the present invention, Patent Document 1 relates to a technique of an image forming apparatus that sequentially transfers an image formed on an image carrier such as a photoconductor onto a sheet to form an image. . The technology provides a background stain detection means for detecting the background stain on the image carrier provided after the development and before cleaning, and periodically operates the background stain detection means so that the output value becomes a predetermined value or less. And a control means for forming a toner image having the full image forming width on the image carrier. For this reason, the background stain is periodically detected by the background stain detection means, and when the output value becomes a predetermined value or less, a toner image is formed on the image carrier, and when cleaning, the image is taken together with the toner of the toner image. Fine powder aggregated on the carrier can be removed.

Japanese Patent Laid-Open No. 10-312143

  On the other hand, the following are conventionally known as means for avoiding the above-mentioned problems. As a first method, when a rubber blade is used as a cleaning means for the image bearing member or the intermediate transfer member, the adhesion is scraped off by increasing the contact pressure of the rubber blade to the image bearing member or the intermediate transfer member. It is a way to improve ability. However, in this case, as a side effect, the surface of the image bearing member or the intermediate transfer member may be scraped or scratched, and a streaky abnormal image may be generated on the image. . Further, since the wear of the rubber blade is likely to progress by increasing the contact pressure, the durability of the rubber blade itself may be lowered.

  Further, as a second method, there is a method of scraping off the adhered matter by bringing a brush member or the like into contact with the image bearing member or the intermediate transfer member as a means different from the cleaning means. However, in this case, there is a problem of space and cost for newly installing the brush member, and a means for collecting the deposits scraped by the brush member from the brush member itself is also required. There is a problem that leads to enlargement, complexity, and cost increase.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to have a simple configuration, and can remove the adhered matter as much as necessary when necessary, and always requires a minimum amount of time and toner consumption. An object of the present invention is to provide an image forming apparatus capable of obtaining a good image quality.

As means for solving the above problems, the present invention has the following features.
2. The image forming apparatus according to claim 1, wherein the toner image formed on the image carrier is primarily transferred onto the intermediate transfer member by the primary transfer unit, and the toner image on the intermediate transfer member is transferred to the secondary transfer unit. The toner image remaining on the image carrier without being transferred to the intermediate transfer member during the primary transfer is removed by the image carrier cleaning means, and is not transferred to the transfer material during the secondary transfer. In the image forming apparatus for removing the toner image remaining on the intermediate transfer body by the intermediate transfer body cleaning means, the image forming apparatus includes a control means for performing the cleaning operation of the image carrier and the intermediate transfer body in addition to the image formation. The toner image is formed on the image bearing member, and the toner image is transferred to the intermediate transfer member by forming a predetermined transfer electric field on the intermediate transfer member by the primary transfer unit, and transferred to the intermediate transfer member. The toner image remaining on the image carrier without being removed is removed by the image carrier cleaning means, and the toner image transferred onto the intermediate transfer body is removed by the intermediate transfer body cleaning means. And
The image forming apparatus according to claim 2 is characterized in that in the image forming apparatus according to claim 1, a lubricant is applied to at least one of the image carrier and the intermediate transfer member.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the predetermined transfer electric field depends on a situation in which toner is to be distributed on the image carrier and the intermediate transfer body. Variable control.
The image forming apparatus according to claim 4, wherein in the image forming apparatus according to any one of claims 1 to 3, toner images are formed on a plurality of image carriers, and the toner images are superimposed on an intermediate transfer member. It is characterized by transferring together.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image carrier that forms a toner image preferentially uses a color that consumes less toner. And

As described above, according to the means for solving the above problems, the image forming apparatus of the present invention has the following effects.
According to the first aspect of the present invention, it is possible to remove deposits on the photosensitive member and the intermediate transfer member without installing a special device, and it is possible to provide a high-quality image forming apparatus. There is.
According to the second aspect of the invention, the adhesion itself to the photosensitive member and the intermediate transfer member is reduced, so that a more excellent effect can be added.
According to the third aspect of the present invention, the deposit removal mode of the photosensitive member and the intermediate transfer member can be performed at the same time, and therefore, the deposit removal mode can be shortened.
According to the fourth aspect of the invention, since a plurality of toner images are formed on the intermediate transfer member at the same time, the time required for the deposit removal mode can be shortened.
According to the fifth aspect of the present invention, it is possible to reduce the stagnation of infrequently used toner in the developing unit, so that it is possible to provide an effect of preventing problems caused by the stagnation toner.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, specific member names are used to facilitate understanding of the invention, but it should be clearly stated that the scope of the present invention is not limited thereby.

<Description of the entire device>
FIG. 1 is a schematic view of an electrophotographic apparatus of a tandem type intermediate transfer system that is an application example of the present invention. In the figure, reference numeral 1 is a tandem image forming apparatus, 2 is a writing optical apparatus, 3 is a paper feed table that supports the whole, 4 is a conveying / reversing apparatus, and 5 is a fixing apparatus that finally fixes an image to a transfer material. ing.
FIG. 2 is an enlarged view of the image forming portion of this figure. The tandem image forming apparatus 1 is provided with an endless belt-shaped intermediate transfer member 501 at the center. The intermediate transfer member 501 is made of rubber or resin having a single layer or multilayer structure.
The intermediate transfer member 501 is stretched by a secondary transfer bias roller 502 and support rollers 503, 508, 509, and 510, and can rotate counterclockwise in the illustrated example. Further, a secondary transfer unit 600 is installed on the opposite side of the intermediate transfer body 501 with respect to the secondary transfer bias roller 502 so as to face the secondary transfer bias roller 502.

The secondary transfer bias roller 502 can form an electric field having the same polarity as that of the toner by a secondary transfer electric field forming unit (not shown). The electrostatic repulsive force generated by the secondary transfer bias roller 502 can apply the toner to the transfer material. Secondary transfer can be performed. An intermediate transfer member cleaning device 520 that removes residual toner remaining on the intermediate transfer member 501 after image transfer is provided on the left side of the support roller 509.
FIG. 3 is an enlarged view of the intermediate transfer member cleaning device 520. The intermediate transfer body cleaning device 520 includes a blade member 521 for removing a toner image, a coil member 524 for conveying the removed toner image to a waste toner tank of the main body, a lubricant 523, and a lubricant application brush 522. Has been. The contact angle, position, pressure, and the like of the blade member 521 are appropriately set depending on the toner used, the image forming speed of the apparatus, and the like. The lubricant 523 is pressed against the lubricant application brush 522 by means such as a spring or a weight, and the lubricant application brush 522 scrapes the lubricant 523 while rotating and applies the lubricant to the intermediate transfer member 501. I do.

In addition, inside the intermediate transfer member 501 between the support roller 503 and the support roller 508, primary transfer bias rollers 504, 505, 506, and 507 that form an electric field during primary transfer can contact the intermediate transfer member 501. Is arranged in. Then, on the opposite side of the primary transfer bias rollers 504, 505, 506, and 507 across the intermediate transfer member 501, four photosensitive members 101, 102, and 103 of yellow, cyan, magenta, and black are arranged along the conveyance direction. A tandem image forming apparatus is configured by arranging 104 side by side.
Around each of the photoconductors 101 to 104, photoconductor charging units 201 to 204, photoconductor cleaning units 301 to 304, and developing units 401 to 404 are arranged, respectively.

The details of the cleaning means 301 to 304 are shown in FIG. The cleaning units 301 to 304 include a blade member 311 for removing a toner image, a coil member 314 for conveying the removed toner image to a waste toner tank of the main body, a lubricant 313, and a lubricant application brush 312. ing. The contact angle, position, pressure, and the like of the blade member 311 are appropriately set depending on the toner used, the image forming speed of the apparatus, and the like. The lubricant 313 is pressed against the lubricant application brush 312 by means such as a spring or a weight, and the lubricant application brush 312 scrapes the lubricant 313 while rotating to apply the lubricant to the photoconductors 101 to 104. Perform the action.
Writing exposure to the photosensitive member is performed by laser irradiation with an exposure device (not shown) at a position between the photosensitive member charging units 201 to 204 and the developing units 401 to 404. A registration roller 800 that feeds the recording medium P to the secondary transfer unit is installed below the secondary transfer unit 600, and a fixing device 5 that fixes the toner image on the recording medium is installed above the registration roller 800.

<Normal image forming operation>
Now, when an image forming operation is performed using this color electrophotographic apparatus, an image signal is first input from a personal computer or a scanner (not shown). At a predetermined timing after the signal is input, the photosensitive members 101 to 104 and the intermediate transfer member 501 are rotated by a drive motor (not shown).
Simultaneously with the photoconductors 101 to 104, a preliminary cleaning operation by the photoconductor cleaning units 301 to 304 is performed, and thereafter, a charging operation by the photoconductor charging units 201 to 204, an exposure operation by an exposure unit (not shown), and developing units 401 to 404. The developing operation is performed. The toner images formed on the photoconductors 101 to 104 in this way are formed on the intermediate transfer member 501 by forming an electric field having a polarity opposite to that of the toner on the primary transfer bias rollers 504 to 507 at predetermined timings, respectively. Transferred to form a single or multicolor visible image. At that time, the toner images remaining on the photoconductors 101 to 104 without being completely transferred onto the intermediate transfer body 501 are cleaned by the photoconductor cleaning units 301 to 304, respectively.

  On the other hand, after the input of the image signal, the recording medium P is fed out from the paper feed table 3 at a predetermined timing, and is abutted against the registration roller 800 and stopped. Then, the registration roller 800 is rotated in synchronization with the visible image on the intermediate transfer member 501, and the recording medium P is fed between the intermediate transfer member 501 and the secondary transfer unit 600. At the same time, an electric field having the same polarity as the toner is formed on the secondary transfer bias roller 502 by the secondary transfer electric field forming means, and the visible image on the intermediate transfer member 501 is secondarily transferred onto the recording medium P. Thereafter, the recording medium P passes through the fixing device 5 and heat and pressure are applied to fix the visible image on the transfer material. On the other hand, the toner image remaining on the intermediate transfer member 501 without being completely transferred onto the recording medium P during the secondary transfer is removed by the intermediate transfer member cleaning device 520 to prepare for the image formation again.

<Description of the present invention part>
Next, parts related to the present invention will be described.
In the present invention, the following cleaning operation (hereinafter referred to as a deposit removal mode) is performed in addition to the normal image formation. First, when the deposit removal mode for the photoconductors 101 to 104 and the intermediate transfer body 501 is activated, the tandem image forming apparatus 1 applies to at least a part of the photoconductors 101 to 104 as in the normal image forming operation. A toner image is formed, an electric field having a polarity opposite to that of the toner is formed by primary transfer bias rollers 504 to 507, and the toner image is primarily transferred onto the intermediate transfer member 501. Unlike normal image formation, the toner image on the intermediate transfer member 501 is conveyed to the intermediate transfer member cleaning device 520 without being subjected to secondary transfer to the transfer material, and is scraped off by the rubber blade 521 there. However, the idling operation is performed for a certain time. Further, the minute residual toner on the photoconductors 101 to 104 that could not be transferred onto the intermediate transfer body 501 is scraped and removed in the same manner by the photoconductor cleaning devices 301 to 304. At the same time, lubricants 313 and 523 are applied to the photoreceptors 101 to 104 and the intermediate transfer member 501 by the lubricant application brushes 312 and 522, respectively.

  By the above operation, the following effects are produced on the adherents on the photoconductors 101 to 104 and the intermediate transfer member 501. First, the toner cleaning devices 301 to 304 and the intermediate transfer member cleaning device 520 are normally attached to the surface by causing a toner image larger than the amount of toner that normally enters (transfer residual toner amount) to enter. The substance is attached to the toner image so as to be entangled and cleaned together with the toner. In order to have this effect, a certain amount of toner image is required, and the normal transfer residual toner alone is insufficient in power, so such an operation is performed.

  The toner amount is adjusted by a charging operation by the photosensitive member charging units 201 to 204, an exposure operation by an exposure unit (not shown), a developing operation by the developing units 401 to 404, and the like. There are several methods for this adjustment. One is to charge the photoconductors 101 to 104 by the photoconductor charging units 201 to 204 and to expose the photoconductors by an exposure unit (not shown) as in the normal image forming operation. In this method, a developing operation is performed by the developing units 401 to 404. However, in the case of an apparatus using an AC electric field for the photoconductor charging units 201 to 204, there are cases where oxidation products are formed on the photoconductors 101 to 104 by ozone generated by AC. Therefore, in order to prevent AC from being applied as much as possible, as a second method, toner image formation is simply performed by the output of the developing means 401 to 404 without performing output by the photosensitive member charging means 201 to 204 and the exposure means (not shown). There is a way to do.

  As shown in FIG. 5A, the electric field applied to the primary transfer bias rollers 504 to 507 when transferring the toner images formed on the photoreceptors 101 to 104 to the intermediate transfer member 501 as shown in FIG. By adjusting the intensity of toner, it is possible to distribute the toner amount. For example, when it is desired to apply the deposit removal mode only to the photoconductors 101 to 104, a toner image of a necessary amount is formed on the photoconductors 101 to 104 on the photoconductors 101 to 104, and the primary transfer bias roller 504 is formed. By turning off the electric field of ˜507, almost all of the formed toner images can be plunged into the photoconductors 101 to 104.

  Further, as shown in FIG. 5B, when it is desired to apply the deposit removal mode only to the intermediate transfer member, toner images necessary for removing the deposit on the intermediate transfer member 501 are transferred to the photoconductors 101 to 101. By applying an optimal transfer electric field to the primary transfer bias rollers 504 to 507 formed on the transfer roller 104, almost all toner images can be transferred to the intermediate transfer member 501 and used in the deposit removal mode.

  Further, as shown in FIG. 5C, when both of them are desired to enter the deposit removal mode at the same time, a total amount necessary for both is formed on the photoconductors 101 to 104, and the primary transfer bias roller 504 is formed. By forming an electric field weaker than the optimum transfer electric field at ˜507, the toner can be distributed to both, and the deposit removal mode can be applied at the same time.

In this way, if the deposit removal mode is performed at the same time, it is possible to shorten the time during which the deposit removal mode is operated, compared to the case where the deposit removal mode of the photosensitive member and the intermediate transfer member is performed separately. User waiting time can be reduced.
The deposit removal mode using the toner image has been described above. Another effect that can be expected from the deposit removal mode described above is an effect of reducing the deposit itself by applying the lubricant. By applying the lubricant to the photoconductors 101 to 104 and the intermediate transfer body 501, the friction coefficient of the both decreases, and it can be expected that the surface is more difficult to deposit.

  In this embodiment, an example in which a lubricant is applied to both the photoconductors 101 to 104 and the intermediate transfer member 501 has been shown. However, the effect can be expected by applying the lubricant to either one of them. For example, even when a lubricant is applied only to the photoconductors 101 to 104, the lubricant on the photoconductor is transferred to the intermediate transfer member 501, so that the friction coefficient on the surface of the intermediate transfer member 501 may be indirectly reduced. This is because it can.

  In addition, when a toner image used for the deposit removal mode is preferentially used for a color that is not frequently used, a margin for the following problems can be improved. Colors that are not used frequently are stirred while the toner stays in the developing means, so the additive is buried or crushed and fine particles are generated, which reduces the charge amount and affects the image quality. It has been known. In the deposit removal mode, the effect is not affected by the decrease in the charge amount. Therefore, by preferentially using colors that are not used frequently, it is possible to avoid using toner evenly and staying in the developing means. In addition, the effect of preventing image quality degradation when an image is formed can be used in combination.

It is also effective to use this more positively, even when it is not necessary to enter the extraneous matter removal mode for the photoconductor of the color where the toner is frequently used, when the extraneous matter removal mode is entered. It is also possible to always replace the toner by forming a toner image. A deposit removal mode may be set for all colors simultaneously. If all the colors are simultaneously and the deposit removal mode of the intermediate transfer member 501 is also performed simultaneously, the time efficiency is the best. Furthermore, if the toner images of all colors are formed on the intermediate transfer body 501 at that time, the time efficiency is still good.
However, since the adhering matter removal mode consumes toner, a color that is likely to run out of toner may be switched and used by providing control so that the adhering matter removing mode is not used as much as possible. In addition, it is preferable that the user can selectively set whether to give priority to image quality or to reduce toner consumption.

<Specific conditions of examples>
Next, more specific conditions of the embodiment will be described. As the photoconductors 101 to 104, an organic photoconductor (OPC) is used, and a laser beam corresponding to an image of an original is irradiated onto a photoconductor uniformly charged to −200 to −2000 V by a charging roller (not shown). Then, optical writing is performed to form an electrostatic latent image. The toner is negatively positively developed using a negatively chargeable toner to form a toner image on the photoconductors 101-104.
As a cleaning means for the photoconductors 101 to 104, urethane rubber was used for the blade member 311 as a cleaning member.
As the intermediate transfer member 501, an intermediate transfer belt made of a thermosetting resin having a thickness of 0.10 mm, a width of 246 mm, and an inner peripheral length of 796 mm was used, and the moving speed of the intermediate transfer belt 501 was set to 155 mm / sec. When the volume resistivity of the entire intermediate transfer belt formed of such a material was measured, it was 10 ⁷ to 10 ¹² Ωcm. Each volume resistivity is measured by applying a voltage of 100 V for 10 seconds using the measuring method described in JISK6911.

The surface resistivity of the intermediate transfer belt 501 was 10 ⁹ to 10 ¹⁴ Ω / □ when measured with a resistance measuring instrument “HI-LESTAR IP” manufactured by Mitsubishi Yuka. This surface resistivity can be measured by the surface resistance measurement method described in JISK 6911 as well as using the resistance measuring instrument. As the support rollers 503, 508, and 509, metal rollers or rubber rollers having a diameter of 12 mm to 26 mm were used, and the width of the rollers was set to 236 mm in order to prevent the intermediate transfer belt 501 from meandering. The support roller 510 has a diameter of 12 mm and a width of 230 mm, and the width is smaller than other support rollers. For the support roller 510, a urethane rubber blade member 521 is provided as a cleaning member.

表１（ａ）は、通常の作像時と同じようにトナー画像を形成した場合で、表１（ｂ）は、帯電手段を利用せずにトナー画像を形成した場合の設定例である。 As a secondary transfer counter roller (not shown), a roller made of urethane foam resin having a diameter of 26 mm and a width of 230 mm was used. In addition, the electric field applied to the secondary transfer electric field forming means for the secondary transfer is a region where the current is about 0 to 100 μA and the voltage is about 0 to −4 kV when a negatively chargeable toner is used as the toner. .
Table 1 shows examples of outputs from the charging means 201 to 204, outputs from the exposure means (not shown), outputs from the developing means 401 to 404, and outputs from the primary transfer bias rollers 504 to 507 in the deposit removal mode. .

Table 1 (a) shows a setting example when a toner image is formed in the same manner as in normal image formation, and Table 1 (b) shows a setting example when a toner image is formed without using charging means.

1 is a schematic configuration diagram of a tandem image forming apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram of an image forming portion in the present embodiment. FIG. 3 is a schematic diagram illustrating an intermediate transfer member cleaning device in the present embodiment. FIG. 2 is a schematic view showing a photoconductor cleaning device in the present embodiment. Schematic explaining the deposit removal mode in the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tandem image forming apparatus 2 Writing optical apparatus 3 Feeding table 4 Conveying / reversing apparatus 5 Fixing apparatuses 101-104 Photoconductor 201-201 Photoconductor charging means 301-304 Photoconductor cleaning means 311 Blade member 312 Lubricant application brush 313 Lubrication Agent 314 Coil members 401 to 404 Developing means 501 Intermediate transfer member 502 Secondary transfer bias rollers 503 and 508 to 510 Support rollers 504 to 507 Primary transfer bias roller 520 Intermediate transfer member cleaning device 521 Blade member 522 Lubricant application brush 523 Lubrication Agent 524 Coil member 600 Secondary transfer unit 800 Registration roller

Claims (5)

The toner image formed on the image carrier is primarily transferred onto the intermediate transfer member by the primary transfer unit, and the toner image on the intermediate transfer member is secondarily transferred onto the transfer material by the secondary transfer unit. The toner image remaining on the image carrier without being transferred to the intermediate transfer member during the next transfer is removed by the image carrier cleaning means, and the toner image remaining on the intermediate transfer member without being transferred to the transfer material during the secondary transfer is intermediate In the image forming apparatus to be removed by the transfer body cleaning means,
In addition to the time of image formation, a control means for performing a cleaning operation of the image carrier and the intermediate transfer member,
The control unit forms a toner image on the image carrier, and transfers the toner image to the intermediate transfer member by forming a predetermined transfer electric field on the intermediate transfer member by the primary transfer unit.
The toner image remaining on the image carrier without being transferred to the intermediate transfer member is removed by the image carrier cleaning means,
The toner image transferred onto the intermediate transfer member is removed by the intermediate transfer member cleaning means.
An image forming apparatus. The image forming apparatus according to claim 1, wherein a lubricant is applied to at least one of the image carrier and the intermediate transfer member. 3. The image forming apparatus according to claim 1, wherein the predetermined transfer electric field is variably controlled according to a situation where toner is desired to be distributed on the image carrier and the intermediate transfer member. 4. The image forming apparatus according to claim 1, wherein toner images are formed on a plurality of image carriers, and the toner images are transferred onto the intermediate transfer member in an overlapping manner. 5. The image forming apparatus according to claim 1, wherein an image carrier that forms a toner image preferentially uses a color that consumes less toner. 6.

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