JP2008145911A - Discharge product removing unit and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge product removing unit which can remove the discharge products that stick to the image forming surface of a rotating photoreceptor, in a fully stabilized manner, and to provide an image forming device which can form superior images, without the risk of generation of forming image defects with the sticking discharge products or other image defects. <P>SOLUTION: This discharge product removing unit (3A) has a rotating toner holder (30), holding the toner remaining on the image forming surface of an image forming medium (12), and a toner retriever (40), in contact with or close to the surface of this rotating toner holder to collect the toner on the surface, detectors (50, 51) to find the toner amount held on the rotating toner holder, and an adjusting means (60), to control the toner collection capabilities of the toner retriever based on the output of the detectors. The image forming device (1) incorporates this discharge product removing unit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge product removing apparatus and an image forming apparatus using the same.

  In an image forming apparatus typified by a printer, a copying machine, a facsimile, or the like that forms an image composed of toner as a developer on a recording medium such as various types of paper, an image is formed of a photosensitive member or the like when the image is formed. The body is charged to a predetermined potential by a charging device such as a corona discharge method or a contact charging method. At this time, a discharge product is generated by the discharge generated during the charging, and it may adhere to the image forming surface of the image forming body. The discharge product is an active substance such as nitrogen oxide or ozone generated during discharge or a reaction product thereof. Further, such a discharge product is not limited to the charging device, but may be generated in a transfer device or a static eliminator that performs corona discharge or contact electrostatic transfer.

  When such a discharge product adheres to the image forming body, when the discharge product adsorbs moisture in the air, the portion of the image forming surface to which the discharge product of the image forming body adheres is electrically Since the resistance becomes low, the predetermined potential cannot be maintained. As a result, image defects such as white spots (image flow) due to the lateral flow of the potential of the electrostatic latent image occur.

  As a countermeasure against this, an image forming apparatus is known in which a friction coefficient adjusting member mainly composed of an ultrafine fiber nonwoven fabric is rubbed on the surface of a photoreceptor after toner removal or toner cleaning (Patent Document). 1). According to this image forming apparatus, since the friction coefficient adjusting member is rubbed against the surface of the photoconductor, the corona product adhering to the photoconductor after toner removal or the like can be easily performed while suppressing wear of the photoconductive layer. It is supposed that the image quality can be maintained over a long period of time without causing image flow.

Japanese Patent Laid-Open No. 2002-258666

  The present invention provides a discharge product removing device capable of sufficiently and stably removing discharge products adhering to an image forming surface of an image forming body such as a rotating photoreceptor, and such a discharge. It is an object of the present invention to provide an image forming apparatus that can perform good image formation without causing image defects due to adhesion of products and other new image defects.

  The discharge product removing device (A1) of the present invention has an image forming surface on which a toner image is formed and rotates in contact with the image forming surface of the rotating image forming body, and remains on the image forming surface. A toner holding rotating body provided with a surface material having conductive fibers for holding toner, and a toner that contacts or is close to the surface material of the toner holding rotating body and collects the toner held on the surface material A collecting member, a detecting means for detecting the amount of toner held on the toner holding rotating body, and an adjusting means for adjusting the toner collecting ability of the toner collecting member according to a detection result of the detecting means. Is included.

  In the discharge product removing device (A2) of the present invention, in the discharge product removing device (A1), the detection means measures, for example, an electric resistance value between the toner holding rotator and the toner recovery member. It is a means to do.

  In the discharge product removing device (A3) of the present invention, in the discharge product removing device (A1), the detecting means measures the concentration of toner held on the surface material of the toner holding rotating body. It is a means.

  In the discharge product removing device (A4) according to the present invention, in the discharge product removing device (A1), the adjustment unit may collect the toner when, for example, a detection result of the detecting unit exceeds a predetermined upper limit value. Adjustment to increase the ability of the member to collect toner is performed.

  Further, the discharge product removing device (A5) of the present invention is the discharge product removing device (A1 or A4), wherein when the adjustment means falls below a predetermined lower limit value, Adjustment is performed to reduce the toner collecting member's ability to collect toner.

  An image forming apparatus (B1) according to the present invention comprises an image forming body having an image forming surface on which a toner image is formed and rotating, an image forming means for forming a toner image on the image forming surface of the image forming body, A discharge product removing device that removes a discharge product that contacts an image forming surface of an image forming body and adheres to the image forming surface, wherein the discharge product removing device is one of the discharge product removing devices described above (Any one of A1 to A5).

  The image forming apparatus (B2) according to the present invention includes a transfer unit that transfers a toner image formed on the image forming body to a transfer body in the image forming apparatus (B1), and the toner image transferred by the transfer unit. Cleaning means for removing toner remaining on the image forming body, and the discharge product removing device is located on the image forming surface of the image forming body on the downstream side in the rotation direction of the image forming body with respect to the transfer means. And it installs in the area | region which becomes the rotation direction upstream rather than the said cleaning means.

  According to the discharge product removing device (A1) of the present invention, the toner holding rotating body provided with the surface material rotates in contact with the image forming surface of the image forming body. While the toner held on the image forming body is interposed between the image forming surface and the image forming surface, the discharge products adhering to the image forming surface are captured and removed. In addition, the toner held on the surface material of the toner holding rotator is appropriately recovered by adjusting the toner recovery capability.

  Thus, in the discharge product removing device (A1), the toner is held on the surface material of the toner holding rotating body and the amount of the held toner is maintained at a required amount. The discharge products adhering to the image forming surface of the body can be removed sufficiently and stably. At this time, for example, even if the amount of toner remaining on the image forming surface of the image forming body becomes large, the amount of toner held on the surface material of the toner holding rotating body is too much than necessary. In addition, there is no possibility that a part of the excessive toner is transferred to the image forming surface of the image forming body and a new image defect due to the transferred toner is generated.

  According to the discharge product removing device (A2), the amount of toner held on the surface material of the toner holding rotator can be easily predicted from the electric resistance value between the toner holding rotator and the toner recovery member. The toner holding amount can be easily adjusted.

  According to the discharge product removing device (A3), the amount of toner held on the surface material of the toner holding rotator can be easily predicted and detected from the density of the held toner. The toner holding amount can be easily adjusted.

  According to the discharge product removing device (A4), when the amount of toner held on the surface material of the toner holding rotating body exceeds the required amount, the amount of toner collected by the toner collecting member is reduced. Therefore, the toner holding amount is maintained at a required amount. In this case, in particular, when the amount of toner held on the surface material of the toner holding rotating body becomes too much, a part of the excessive toner is transferred to the image forming surface of the image forming body, and is transferred. It is possible to prevent a new image defect caused by the toner.

  According to the discharge product removing device (A5), the amount of toner collected by the toner collecting member when the amount of toner held on the surface material of the toner holding rotating body becomes too small below the required amount. Therefore, the toner holding amount is maintained at a required amount. In this case, in particular, since the amount of toner held on the surface material of the toner holding rotating body becomes too small, the discharge product removal performance by the held toner is prevented from deteriorating. The

  According to the image forming apparatus (B1) of the present invention, the discharge product adhering to the image forming surface of the image forming body is sufficiently and stable by the discharge product removing device (any one of A1 to A5). To be removed. As a result, an image defect due to the adhesion of the discharge product may occur, and other new image defects (for example, the amount of toner held on the toner holding rotator is too large, and the excess It is possible to form a good image without causing an image defect caused by transfer of a part of the toner to the image forming body.

  According to the image forming apparatus (B2), the toner remaining on the image forming surface of the image forming body after passing through the transfer means reaches the toner holding rotating body and is held thereby. The removal performance of the discharge product through the toner by the rotating body is easily maintained. In addition, even if a part of the toner held on the toner holding rotating body falls off and is transferred to the image forming surface of the image forming body, it is removed by the cleaning means, thereby transferring to the image forming surface. The occurrence of image defects due to the presence of toner is prevented.

[Embodiment 1]
1 and 2 show a discharge product removing apparatus and a printer according to Embodiment 1, FIG. 1 shows an outline of the entire printer, and FIG. 2 shows a main part of the printer (discharge product removing apparatus). Is shown enlarged.

  The printer 1 includes an image forming device 10 that forms a toner image based on image information and transfers the toner image to a paper 9 inside a device main body (not shown), and passes the paper 9 on which the toner image is transferred. A fixing device 20 that performs fixing and a paper feeding device 25 that supplies paper 9 to the image forming device 10 are mainly equipped. Reference numeral 6 in FIG. 1 is a control device that comprehensively controls the operation and the like of each component of the printer 1, and an alternate long and short dash line with arrows indicates a main conveyance path of the paper 9.

  The image forming apparatus 10 is capable of forming a toner image using, for example, a known electrophotographic method. Specifically, a photosensitive drum 12 that is rotationally driven in the direction of arrow A is provided, and a charging roll that uniformly charges the surface (image forming surface) of the photosensitive drum 12 around the photosensitive drum 12 or the like. And an exposure device comprising an LED array, a laser scanning device, and the like for forming an electrostatic latent image having a potential difference by irradiating the surface of the charged photosensitive drum 12 with light based on image information (signal). 14, a developing device 15 that forms a toner image by transferring and adhering toner to the latent image, a transfer device 16 that includes a transfer roll that transfers the toner image to the paper 9 supplied from the paper supply device 25, and the like. A cleaning device 17 such as a blade type for removing and cleaning toner remaining on the surface of the photosensitive drum 12 after transfer is mainly disposed.

  Among these, the photosensitive drum 12 is obtained by forming a photoconductive layer (photosensitive layer) made of an organic photosensitive material on a cylindrical base material. Further, the exposure device 14 obtains image information input from a device such as a document reading device, a stored information reading device, a personal computer, or the like connected to or installed in the printer 1 by a required process using an image processing device (not shown). The received image signal is input. In this embodiment, the photosensitive drum 12 is charged with negative polarity, and the developing device 15 is applied with toner charged with negative polarity.

  The fixing device 20 is rotatably driven in the direction of the arrow inside the housing 21 and heated to a predetermined temperature, and a heating roller 22 that is pressed and substantially rotated along the axial direction of the heating roll 22. A pressure roll 23 is provided, and the toner image is fixed to the paper 9 by introducing and passing the paper 9 on which the toner image is transferred to the pressure contact portion where both the rolls 22 and 23 are in pressure contact. Is called.

  The paper feeding device 25 includes a paper feeding cassette 26 in which a plurality of paper sheets 9 to be supplied to the image forming device 10 (transfer section thereof) are stacked and accommodated, and one paper 9 accommodated in the paper feeding cassette 26. It mainly includes a delivery mechanism 27 that feeds out one sheet at a time. A plurality of paper feed cassettes 26 are prepared as necessary. Further, the paper feeding device 25 is a pair of paper transporting rolls 28a, 28b, 28c,... For transporting the paper 9 from the paper feeding cassette 26 to the transfer section of the image forming device 10 (between the photosensitive drum 12 and the transfer device 16). And a paper conveyance path composed of guide members and the like. The sheet conveyance path is also provided between the image forming device 10 and the fixing device 20 and between the fixing device 20 and the paper discharge unit (tray or the like) 29. On the paper discharge side of the fixing device 20, a discharge roll pair 28 d that discharges and conveys the fixed paper 9 to the paper discharge unit 29 is installed.

  Further, in the printer 1, discharge products generated during charging (corona discharge, gap discharge, etc.) of the charging device 13 of the image forming device 10 adhere to the peripheral surface (image forming surface) of the photosensitive drum 12. Sometimes. For this reason, as a countermeasure for removing the attached discharge product, a discharge product removing device 3 </ b> A as described below is provided around the photosensitive drum 12.

  That is, as shown in FIG. 2, the discharge product removing device 3A is supported and rotated while being in contact with the image forming surface of the photosensitive drum 12 in the axial direction, and retains the toner remaining on the image forming surface. The toner holding roll 30 provided with the surface material 35 to be rotated and the toner holding roll 31 supported and rotated in contact with the surface material 35 in the axial direction of the toner holding roll 31 to collect the toner held on the surface material 35 The toner collecting roll 40, the toner holding amount detecting device 50 for detecting the amount of toner held in the toner holding roll 30, and the toner collecting roller 40 collecting the toner according to the detection result of the toner holding amount detecting device 50 It has the adjustment apparatus 60 which adjusts the capability to do.

  The discharge product removing device 3 </ b> A also includes a power supply device 70 that applies a toner holding voltage to the toner holding roll 30 and a toner collecting voltage to the toner collecting roll 40, and the toner holding roll 30 and toner collecting roll 40. Is provided with a drive mechanism (not shown) that rotates in a predetermined direction. Such a discharge product removing device 3 </ b> A is downstream of the peripheral surface of the photosensitive drum 12 in the rotational direction A of the photosensitive drum 12 with respect to the transfer device 16, and more upstream of the rotational direction A of the cleaning device 17. It is installed at a predetermined position in the area that becomes the side.

The toner holding roll 30 has a configuration in which a surface material 35 is provided on the peripheral surface of a roll core material 31 made of metal or the like. The surface material 35 is a nonwoven fabric composed of conductive fibers. As the conductive fiber, for example, an insulating fiber made of polyester, nylon or the like contains a conductive material, or a conductive resin is coated on the fiber (raw material) to impart conductivity. used. The electroconductivity refers to a characteristic showing a volume resistance value in the range of 10 ⁵ to 10 ¹³ Ω · cm. Further, the surface material 35 is formed by, for example, forming the non-woven fabric into a band having a predetermined width, and then fixing the non-woven fabric so as to be wound around the roll core material 31 in a spiral manner. The surface material 35 is fixed to the roll core material 31 using a conductive adhesive or the like. The conductive fibers are preferably ultrafine fibers having a fiber thickness of 1 to 30 μm.

  The toner collecting roll 40 has a configuration in which a coating layer 42 is provided on a roll core material 41 made of metal or the like. The covering layer 42 is formed using, for example, hard rubber, a carbon-containing phenol resin, or the like. The collecting roll 40 is provided with a removing member 43 such as a blade plate for removing the toner collected and adhered to the roll surface (coating layer 42). In this embodiment, the toner collection roll 40 is placed in contact with the surface material 35 of the toner holding roll 31, but the toner held on the surface material 35 of the holding roll 31 is electrostatically adsorbed. If it can be recovered, the surface material 35 may be installed in a state of being close to each other with a small gap of about 1.5 mm or less, for example.

  The toner holding amount detection device 50 measures the electric resistance value between the toner holding roll 30 and the toner collecting roll 40 to thereby predict and detect the amount of toner held in the toner holding roll 30. The device 51 is provided. The detection device 51 applies a constant current (I) for resistance measurement from the power supply device 70 between the core material 31 of the toner holding roll 30 and the core material 41 of the toner recovery member 40, and the voltage value ( After measuring V) with a voltmeter, the resistance (R = V / I) is calculated from Ohm's law, and this is used as the electrical resistance value (Rn: system resistance).

  The adjusting device 60 is configured to adjust the ability of the toner collecting roll 40 to collect toner according to a preset control program in accordance with the electric resistance value Rn that is the detection result of the toner holding amount detecting device 50 (51). Has been. In this embodiment, sequence control relating to toner recovery (to be appropriately selected based on the relationship between the detection result and the threshold) as shown in FIG. In addition, the control device 60 is normally configured as a part of the control device 6 of the printer 1, but may be configured by a microcomputer or the like independent of the control device 6. Further, the adjustment of the toner recovery capability by the adjusting device 60 is always performed continuously in conjunction with the time when the toner is held on the toner holding roll 30 and the discharge product is removed, but is set in advance. It may be performed only at a predetermined adjustment time. The predetermined adjustment time can be set to a time such as a non-image formation time when image formation by the image forming device 10 is not performed (inserted and executed as an adjustment mode or the like), for example.

  Further, in this discharge product removing device 3A, since the positive polarity toner remaining on the photosensitive drum 12 is adsorbed and held by the electrostatic action from the power supply device 70 to the toner holding roll 30, the toner holding voltage is used. A negative polarity DC voltage is applied. In addition, a DC voltage having a larger value on the negative polarity side than the toner holding voltage is applied to the toner collecting roll 40 as the toner collecting voltage. Further, the toner holding roll 30 and the toner collecting roll 40 are rotated in a direction (clockwise direction) opposite to the rotation direction of the photosensitive drum 12 (counterclockwise direction in the example shown in FIG. 2). This rotation direction may be the same as the rotation direction of the photosensitive drum. Such rotation is performed by applying a drive mechanism including an independent rotational power source (motor, etc.) and a power transmission mechanism, and other components (photosensitive drum, cleaning rotary brush, etc.) are used as the rotational power source. It is also possible to apply a drive mechanism that uses the power source of) and transmits the power of the rotational power source by a power transmission mechanism.

  Next, each operation in the printer 1 will be described.

  First, a basic print operation will be described. When the printer 1 receives a print start command, the photosensitive drum 12 starts to rotate in the image forming device 10 and the surface thereof is charged to a predetermined negative potential by the charging device 13 and then exposed to the charged photosensitive drum 12. Exposure by the device 14 is performed based on the image signal to form an electrostatic latent image. Subsequently, when the latent image passes through the developing device 15, the latent image is developed with a negatively charged toner to form a toner image, and then the toner image is fed from the paper feeding device 25 at a transfer portion facing the transfer device 16. It is electrostatically transferred to the sheet 9 conveyed at a predetermined timing through the path. After the transfer, the photosensitive drum 12 is cleaned by removing residual toner (negatively charged), paper dust, and the like on the surface by the cleaning device 17.

  The sheet 9 on which the toner image has been transferred is conveyed so as to be introduced into the fixing device 20, and is heated and pressed when passing through the pressure contact portion between the heating roll 22 and the pressure roll 23 in the fixing device 20. Thus, the toner image is fixed. Thereafter, the sheet 9 after fixing is discharged to the paper discharge unit 29 by the discharge roll pair 28d and stacked and accommodated. As a result, the basic printing operation for one sheet is completed. Further, when there are a plurality of print instructions, the above-described series of operations is similarly repeated for the number of prints.

  Next, the operation of the discharge product removal device 3A will be described.

  The discharge product removing device 3A operates in conjunction with the rotation operation of the photosensitive drum 12 at the time when the printing operation as described above is executed. First, when the photosensitive drum 12 starts to rotate due to the start of the printing operation, the toner holding roll 30 and the toner recovery roll 40 start to rotate, and a toner holding voltage is applied to the toner holding roll 30 from the power supply device 70. Further, in the removing device 3A, a constant voltage is applied from the power supply device 70 to the toner collecting roll 40 at a time that is not a toner collecting time (toner non-collecting time) as will be described later. This constant voltage prevents the toner held on the toner collecting roll 40 from inadvertently transferring to the toner collecting roll 40 during the toner non-collecting time by electrostatic action, and the amount of the held toner. Is applied in order to keep the minimum amount necessary for removal of discharge products.

  When the printing operation is executed, as shown in FIG. 4, the toner Ta or the like remaining on the surface of the photosensitive drum 12 without being transferred to the paper 9 side in the transfer process by the transfer device 16 is discharged to the discharge product removing device. It is transported toward 3A. When at least a part Ta (+) charged to a positive polarity (reverse) in the residual toner Ta reaches the surface portion of the photosensitive drum 12 in contact with the toner holding roll 30 of the removing device 3A, the toner holding roll 30 It is held so as to be attracted to the surface material 35 (conductive fibers thereof) by an electrostatic action generated by the applied toner holding voltage. The toner Ta (+) reversely charged to the positive polarity is one whose charging polarity is reversed mainly by the influence of the positive polarity transfer voltage applied to the transfer device 16 in the transfer portion. In FIG. 4, the symbol Ta (−) indicates that the residual toner Ta is negatively charged.

  As a result, the holding toner Ta (+) held by the conductive fibers of the surface material 35 of the toner holding roll 30 rubs the surface of the photosensitive drum 12 in contact with the holding roll 30. If a discharge product generated during discharge of the charging device 13 or the like adheres to the surface of the photosensitive drum 12, the discharge product is captured by the holding toner Ta (+) so as to be captured by the photosensitive drum 12. Removed from the surface.

  Further, during the operation of the discharge product removing device 3A, as shown in FIG. 3, the toner holding amount detection device 50 detects the amount of the holding toner Ta (+) held on the toner holding roll 30 ( Step S10).

  That is, the resistance measurement type toner holding amount detection device 50 (51) measures the electrical resistance value Rn between the toner holding roll 30 and the toner recovery roll 40 as described above, and the measured electrical resistance value Rn It is determined in adjustment device 60 whether or not preset upper limit value Qmax is exceeded (S11). Here, the upper limit value Qmax is, for example, a viewpoint of whether or not a phenomenon of transferring to the surface of the photosensitive drum 12 due to an excessive amount of the held toner Ta (+) held on the toner holding roll 30 occurs. From the viewpoint of whether or not a phenomenon that is caused to adhere to the surface of the photosensitive drum 12 occurs, it is selected as a resistance value that is likely to be a boundary point of whether or not the phenomenon occurs.

  At this time, when the resistance value Rn is equal to or lower than the upper limit value Qmax, the amount of retained toner Ta (+) retained on the surface material 35 of the toner retaining roll 30 is regarded as an appropriate amount, and the toner collecting roll 40 The toner collection mode to be executed is in an “OFF” state (S12). However, in this embodiment, as described above, a predetermined voltage is applied from the power supply device 70 to the toner collecting roll 40 even in this state.

  On the other hand, when the resistance value Rn exceeds the upper limit value Qmax, it is considered that the holding amount of the holding toner Ta (+) held on the surface material 35 of the toner holding roll 30 is excessive, and the toner recovery mode is “ "ON" state (S13). That is, at this time, the toner collection voltage is applied from the power supply device 70 to the toner collection roll 40.

  As a result, when the retained toner Ta (+) on the surface material 35 of the toner retaining roll 30 passes mainly in contact with the toner collecting roll 40, it is generated by the toner collecting voltage applied to the collecting roll 40. The toner is collected by being attracted to the toner collecting roll 40 side by the electrostatic action.

  Such detection of the holding amount of the holding toner Ta (+) and adjustment of the collection of the holding toner are continuously performed while the printing operation is being executed.

  Therefore, in the printer 1, the toner Ta (+) is held on the surface material 35 of the toner holding roll 30 and the amount of the held toner Ta (+) is required by installing the discharge product removing device 3A. Since the amount is maintained, printing (image formation) that does not cause an image flow phenomenon due to a discharge product adhering to the surface of the photosensitive drum 12 becomes possible. Further, the amount of toner held on the toner holding roll 30 becomes too large, and a part of the excessive toner is transferred to the photosensitive drum 12, and a new image defect caused by the transferred toner is generated. There is no fear.

<Evaluation test>
Hereinafter, a test performed using the printer 1 equipped with the discharge product removing device 3A will be described.

  For the printer 1, an organic photosensitive drum having an outer diameter of 60 mm in which a surface protective layer mainly composed of a phenol resin was formed on the organic photosensitive layer for the purpose of improving durability was used as the photosensitive drum 12. As the developing device 16, a two-component developing device containing a styrene / acryl toner having an average particle diameter of 5.8 μm and a ferrite carrier charged to a negative polarity was used.

  For the discharge product removing device 3A, as the toner holding roll 30, a non-woven fabric (thickness of about 2 to 2) made of polyester-made conductive fibers having a thickness of 0.2 d (denier: equivalent to a diameter of about 5 μm). A roll having a diameter of 17 mm was used in which a surface material 35 formed in a cylindrical shape was covered with a roll core material 31 made of stainless steel and fixed. As the toner collecting roll 40, a roll having an outer diameter of 12 mm in which a coating layer 42 having a thickness of 2 to 3 mm made of a carbon-containing phenol resin was formed on a stainless roll core material 41 was used. As the removing member 43, a scraper made of stainless steel (for example, SUS304) was applied.

  The toner holding roll 30 was installed so as to contact the photosensitive drum 12 with a predetermined pressure. In addition, a toner holding voltage of −300 V is applied to the toner holding roll 30, a toner recovery voltage of −400 V is applied to the toner recovery roll 40 when the recovery mode is ON, and a voltage of −200 V (retention is maintained when the recovery mode is OFF. Voltage for adjustment) was applied. Further, when the photosensitive drum 12 is rotated in the direction indicated by the arrow in FIG. 2 (counterclockwise direction) at a process speed of 320 mm / sec, the toner holding roll 30 is rotated in the direction indicated by the arrow in FIG. 2 (clockwise direction). The toner collection roll 40 was rotated at a speed of 384 mm / sec and rotated in the same direction (clockwise direction) at a speed of 641 mm / sec. In this test, the photosensitive drum 12 was charged to −600 V by the charging device 13. Further, test images described later were formed at a surface potential of −300V. Further, in this test, the surface potential of the photosensitive drum 12 after passing through the transfer device 16 was −200V.

  By using the printer 1 equipped with such a discharge product removing device 3A, a test image (an image portion having an area image density of 8% and a non-image portion are mixed in an environment of a temperature of 28 ° C. and a humidity of 85% RH. Images having the same structure) were continuously printed. In the period until the number of prints reaches the number of prints as shown in FIG. 5, the image defects appearing as the toner held on the toner holding roll 30 is transferred to the photosensitive drum 12 and mixed in the test image of the print result. (So-called “bottom”) occurrence situation was investigated. At the time of this test printing, the upper limit value Qmax in the adjusting device 60 was set to “50 MΩ” to adjust the toner recovery capability (Example). For reference, the toner recovery capability was not adjusted, and a case where a voltage of −200 V in the recovery mode OFF was continuously applied during test printing (comparative example) was also examined in the same manner.

The state of occurrence of image defects (bottoms) at this time was evaluated according to the following criteria. The result is shown in FIG. Incidentally, in this test, it was confirmed that when the discharge product was attached to the photosensitive drum 12 by the operation of the charging device 13 and then passed through the discharge product removing device 3A, the discharge product was removed well. Yes. In addition, before and after this test, when an image for checking image quality (a full-scale image with an image density of 20%) was printed by printing of the example, it was confirmed that no image flow occurred at any time. .
○: No flickering occurred.
[Delta]: A small amount of blur that cannot be visually confirmed occurred.
X: Butter that can be visually confirmed occurred.

  In addition, when the printer 1 equipped with the discharge product removing device 3A having the above-described conditions (in the example and the comparative example) is used to continuously print test images under the same environment, every time an appropriate number of prints is reached. The change in the amount of toner held on the toner holding roll 30 was examined. At this time, regarding the change in the toner amount, the toner adhering to the toner holding roll 40 when the number of printed sheets shown in FIG. 6 is reached is collected by a dust collector on an eye filter smaller than the toner particle diameter. After the toner weight was measured per unit area, it was expressed as the toner density when each number of printed sheets was reached. The results are shown in FIG.

  FIG. 7 shows a toner holding roll 30 and a toner collection roll 40 when a test image is continuously printed in the discharge product removing apparatus 3A of the comparative example used in this test (with no toner collection adjustment). It shows the result of examining the transition of the resistance (system resistance) between the two. The resistance was measured as a value when a current of 16 μA was applied in the toner holding amount detection device 51. In FIG. 7, the system resistance temporarily decreases because the comparative printer 1 was left in a high-temperature and high-humidity environment when the continuous printing of this test was temporarily interrupted. This is probably because moisture in the atmosphere was adsorbed to the system, thereby temporarily reducing the system resistance.

[Embodiment 2]
FIG. 8 shows a main part (another configuration example of the discharge product removing device) of the printer according to the second embodiment of the present invention.

  The printer according to the second embodiment has the same configuration as that of the printer 1 according to the first embodiment except that the discharge product removing device is changed to another configuration example (discharge product removing device 3B). For this reason, in FIG. 8, the same reference numerals are given to the same constituent elements as those in the first embodiment, and the description thereof is omitted in the subsequent steps except when it is necessary (the subsequent embodiments). The same applies to the case of.

  That is, the discharge product removing device 3B according to the second embodiment replaces the resistance measurement type detection device 51 (FIG. 2) according to the first embodiment as the toner holding amount detection device 50, and the surface material 35 of the toner holding roll 30. The configuration is the same as that of the removing device 3A in the first embodiment except that a density measuring type detecting device 55 for measuring the density of the toner held in the toner is applied.

  In the toner holding amount detecting device 50 constituted by the density measuring type detecting device 55, the density value (Dn) of the holding toner Ta (+) held on the surface material 35 of the toner holding roll 30 is measured. The toner holding amount in the holding roll 30 is predicted and detected. As the density measurement type detection device 55, for example, a density sensor based on reflectance used for measurement of a measurement image (so-called patch) for process control is used. In particular, when the toner to be measured is a color toner other than black, a toner that can measure the density of such a color toner is applied. Further, the installation position is preferably in the region between the contact portion with the photosensitive drum 12 and the contact portion with the toner recovery roll 40 as viewed in the rotation direction of the toner holding roll 30, but the other portion. It doesn't matter.

  The adjusting device 60 follows the control program in which the ability of the toner collecting roll 40 to collect toner according to the toner density value (Dn), which is the detection result of the toner holding amount detecting device 50 of the density measuring type detecting device 55, is set in advance. Configured to adjust. In this embodiment, sequence control relating to toner collection as described later and shown in FIG. 9 is executed.

  Next, the main operation of the discharge product removal device 3B to which the detection device 51 of the concentration measurement type detection device 55 is applied will be described.

First, when the printing operation of the printer 1 is executed, as in the case of the discharge product removing device 3A of the first embodiment, at least the positive polarity of the toner Ta or the like remaining without being transferred to the surface of the photosensitive drum 12 is used. A portion Ta (+) reversely charged to the toner is held so as to be adsorbed by the electrostatic action on the surface material 35 (conductive fibers thereof) of the toner holding roll 30 (see FIG. 4).
As a result, the holding toner Ta (+) held on the surface material 35 of the toner holding roll 30 rubs the surface of the photosensitive drum 12 in contact with the holding roll 30, and the surface of the photosensitive drum 12 is charged. If a discharge product generated during the discharge of the device 13 or the like is attached, the discharge product is removed from the surface of the photosensitive drum 12 so as to be captured by the holding toner Ta (+).

  Subsequently, during the operation, as shown in FIG. 9, the amount of the retained toner Ta (+) held on the toner holding roll 30 is detected by the density measuring type toner holding amount detecting device 50 (55) ( Step S20).

  That is, the density measurement type toner holding amount detection device 50 (55) measures the density value Dn of the toner held on the toner holding roll 30 as described above, and the measured density value Dn is preset. Whether or not the upper limit value Jmax is exceeded is determined by the adjustment device 60 (S21).

  At this time, when the density value Dn is equal to or lower than the upper limit value Jmax, the amount of the retained toner Ta (+) retained on the surface material 35 of the toner retaining roll 30 is regarded as an appropriate amount, and the toner collecting roll 40 The toner collection mode to be executed is in an “OFF” state (S22). However, in this embodiment as well, as in the first embodiment, a predetermined voltage is applied from the power supply device 70 to the toner collection roll 40 even in this state.

  On the other hand, when the density value Dn exceeds the upper limit value Jmax, it is considered that the amount of retained toner Ta (+) retained on the surface material 35 of the toner retaining roll 30 is excessive, and the toner recovery mode is “ "ON" state (S23). That is, at this time, the toner collection voltage is applied from the power supply device 70 to the toner collection roll 40.

  As a result, when the retained toner Ta (+) on the surface material 35 of the toner retaining roll 30 passes mainly in contact with the toner collecting roll 40, it is generated by the toner collecting voltage applied to the collecting roll 40. The toner is collected by being attracted to the toner collecting roll 40 side by the electrostatic action.

[Other Embodiments]
In the discharge product removal apparatuses 3A and 3B of the first and second embodiments, the electric resistance value Rn or the density value Dn as a detection result corresponds to the upper limit value of the predetermined range of the toner holding amount with respect to the adjustment of the toner collecting ability of the toner collecting roll 40. Although the description has been given of the case where the determination is made based only on the information on whether or not the upper limit values Qmax and Jmax are exceeded, in addition to the information, for example, as shown in FIG. It can also be configured to take into account information whether or not the value Rn or the density value Dn is below the lower limit values Qmin and Jmin corresponding to the lower limit value of the predetermined range of the toner holding amount.

  In this case, as shown in FIG. 10, after the electrical resistance value Rn or the density value Dn is measured as the toner holding amount detection (S30). In addition to determining whether or not the electrical resistance value Rn or the concentration value Dn exceeds the upper limit values Qmax and Jmax, it is determined whether or not the lower limit values Qmin and Jmin are lower (S31). When the electrical resistance value Rn or the density value Dn is not less than each lower limit value and not more than each upper limit value, the toner recovery mode is turned off (S32), but the electrical resistance value Rn or density value is set. When Dn exceeds each upper limit value, the normal level toner recovery mode is turned on (S33). In addition, when the electrical resistance value Rn or density value Dn falls below the respective lower limit values, the toner collection mode at the reduced level is turned on (S34). As a result, the toner collecting ability of the toner collecting roll 40 is reduced, and the amount of the retained toner held on the toner holding roll 30 is reduced. As a result, the held toner on the toner holding roll 30 is reduced. It is avoided that the amount is less than a predetermined range.

  Incidentally, the toner collection mode at the reduced level is set so that the toner is collected under the condition that the toner collecting ability is reduced as compared with the toner collection mode at the normal level. Further, the toner collection mode at the reduced level is set to a condition in which the ability to collect toner is lower than when the toner collection mode is OFF. For example, in the above-described evaluation test, a voltage of “−400 V” is applied to the toner collection roll 40 as the toner collection voltage when the toner collection mode is turned on, and a predetermined voltage is applied when the toner collection mode is turned off. The voltage of “−200 V” is applied to the toner collecting roll 40 as the toner collecting voltage 40. However, assuming that the toner collecting voltage at that time is “normal level”, the toner collecting voltage to be applied in the reduced level toner collecting mode. May be set to “0V” or “predetermined voltage of the positive pole (+)”.

  Further, in the discharge product removing apparatuses 3A and 3B of the first and second embodiments, a rotary roll type (toner holding roll 30) in which a surface material 35 made of a nonwoven fabric is provided on a roll core 31 as a toner holding rotary body. In addition to this, for example, as shown in FIG. 11, a plurality of conductive brush hairs stand in the normal radial direction from the peripheral surface of the roll core 31. It is also possible to apply a rotary brush type (toner holding brush) 36C provided with a surface material 36 planted on the base fabric at a predetermined density.

  In this case, the discharge product removing device 3C to which the rotary brush type toner holding brush 30C is applied has the same configuration as the discharge product removing devices 3A and 3B of the first and second embodiments except for the toner holding brush 30C. That's fine. The toner holding roll 30 and the toner holding brush 30C can be configured not to apply a toner holding voltage from the power supply device 70 regardless of the type (actually surface material). In such a configuration, the toner remaining on the photosensitive drum 12 is mainly mechanically applied to the conductive fibers of the surface material 35 with respect to the toner holding roll 30 or the toner holding brush 30C to which the toner holding voltage is not applied. Is attached and held.

  Furthermore, in the discharge product removing apparatuses 3A and 3B of the first and second embodiments, the case where the rotary roller type toner holding roll 40 is applied as the toner collecting member has been described. As shown, a plate-like toner recovery plate 45 may be applied. The toner collecting plate 45 is a plate made of a material such as a carbon-containing phenol resin, and is fixed in a state where one end thereof is in contact with the toner holding roll 30 (or the toner holding brush 30C) in the axial direction. Or, the end opposite to the contacted end is attached to the support shaft 46 so as to swing in the directions of arrows C and D.

  In this case, the adjustment of the toner collecting ability in the toner collecting plate 45 is performed by setting the toner holding voltage applied to the collecting plate 45 from the power supply device 70 in the case of the first, second, or other embodiments (toner collecting ability). In the same manner as the configuration including the case where the toner is reduced, the adjustment is performed based on the detection information from the toner holding amount detection device 50. In addition to this, for the adjustment, as shown in FIG. 12, a swinging device (a driving device using a cam mechanism, a gear mechanism, etc.) 47 for swinging the toner collecting plate 45 in the directions of arrows C and D is provided. As in the first and second embodiments, based on the detection information from the toner holding amount detection device 50, the swinging device 47 is driven to rotate the toner holding roller 30 and the like of the toner collecting plate 45. You may make it carry out by adjusting the contact pressure with a body.

  In the first and second embodiments, the type of printer that forms a single color toner image is exemplified as the image forming apparatus, but the type of image that forms a color toner image (image) composed of a plurality of color toners. Needless to say, the forming apparatus can be applied.

FIG. 3 is an explanatory diagram illustrating an overview of a printer according to a first embodiment (second embodiment, others). It is a schematic explanatory drawing which shows the principal part (discharge product removal apparatus in Embodiment 1) of the printer of FIG. 6 is a flowchart illustrating a control sequence for adjusting toner recovery capability according to the first exemplary embodiment. It is a schematic explanatory drawing which shows the operation state of the discharge product removal apparatus in Embodiment 1 grade | etc.,. 6 is a chart showing test results in Embodiment 1. FIG. 6 is a graph showing a result of measuring a transition state of a toner holding amount. It is a graph which shows the result of having measured the transition state of system resistance. It is a schematic explanatory drawing which shows the discharge product removal apparatus in Embodiment 2, etc. 10 is a flowchart illustrating a control sequence for adjusting toner recovery capability according to the second exemplary embodiment. 12 is a flowchart illustrating a control sequence for adjusting toner recovery capability according to another embodiment. FIG. 6 is a schematic diagram of a main part of another configuration example of a discharge product removing device (particularly, a toner holding rotating body). FIG. 10 is a schematic diagram of a main part of another configuration example of a discharge product removing device (particularly a toner recovery member).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer (image forming apparatus), 3A-3D ... Discharge product removal apparatus, 12 ... Photosensitive drum (image forming body), 13 ... Charging apparatus (a part of image forming means), 14 ... Exposure apparatus (image forming means) 15 ... developing device (part of image forming means), 16 ... transfer device (transfer means), 17 ... cleaning device (cleaning means), 30 ... toner holding roll (toner holding rotating body), 30C ... Toner holding brush (toner holding rotating body), 35... Nonwoven fabric (surface material), 36... Brush material (surface material), 40... Toner collecting roll (toner collecting member), 45. DESCRIPTION OF SYMBOLS ... Detection apparatus, 51 ... Resistance measurement type detection apparatus, 55 ... Density measurement type detection apparatus, 60 ... Adjustment apparatus (adjustment means), A ... Rotation direction, Ta ... Residual toner, Ta (+) ... Holding toner.

Claims (7)

A surface material having conductive image fibers having an image forming surface on which a toner image is formed and rotating in contact with the image forming surface of the rotating image forming body and holding toner remaining on the image forming surface. A toner holding rotator provided;
A toner collecting member that contacts or approaches the surface material of the toner holding rotating body and collects the toner held on the surface material;
Detecting means for detecting the amount of toner held on the surface material of the toner holding rotating body;
An apparatus for removing a discharge product, comprising: adjusting means for adjusting the toner collecting ability of the toner collecting member according to the detection result of the detecting means.   The discharged product removal apparatus according to claim 1, wherein the detection unit is a unit that measures an electrical resistance value between the toner holding rotating body and the toner recovery member.   The discharge product removing apparatus according to claim 1, wherein the detection unit is a unit that measures a concentration of toner held on a surface material of the toner holding rotating body.   The discharge product removing device according to claim 1, wherein the adjustment unit performs an adjustment to increase the ability of the toner collection member to collect toner when a detection result of the detection unit exceeds a predetermined upper limit value.   5. The discharge product removal device according to claim 1, wherein the adjustment unit performs adjustment to reduce the toner collecting ability of the toner collecting member when a detection result of the detection unit falls below a predetermined lower limit value. . An image forming body having an image forming surface on which a toner image is formed and rotating;
An image forming means for forming a toner image on the image forming surface of the image forming body;
A discharge product removing device for removing a discharge product attached to the image forming surface in contact with the image forming surface of the image forming body;
An image forming apparatus, wherein the discharge product removing device is the discharge product removing device according to any one of claims 1 to 5. Transfer means for transferring a toner image formed on the image forming body to a transfer body; and cleaning means for removing toner remaining on the image forming surface of the image forming body after the toner image is transferred by the transfer means. Have
The discharge product removing device is installed in an area of the image forming surface of the image forming body that is downstream of the transfer unit in the rotation direction of the image forming body and upstream of the cleaning unit. The image forming apparatus according to claim 6.

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