JP2005181372A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing failure that filming occurs on an intermediate transfer body and preventing the turn-up of the edge part of a blade to the utmost. <P>SOLUTION: The image forming apparatus has a plurality of image carriers and a plurality of developing devices provided to form toner images different in colors from each other on the respective image carriers and constituted by storing developer including color toner, and has constitution where the respective color toner images formed on the image carriers are superposed on the intermediate transfer body and then transferred to recording material from the intermediate transfer body, and the intermediate transfer body to which the toner image has been transferred is cleaned by a cleaning means constituted of the blade. The apparatus has an adjusting mode for actuating the developing device including toner to which a small amount of lubricant is added out of a plurality of developing devices so as to supply the toner to which a small amount of lubricant is added to the blade through the intermediate transfer body in addition to an ordinary color image forming mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus for forming an electrostatic latent image formed on an image carrier, such as a color copying machine and a color printer, into a color toner image by electrophotography, and in particular, formed on a plurality of image carriers. The present invention relates to an image forming apparatus in which images of different color toners are superimposed on an intermediate transfer member and then transferred onto a recording material such as plain paper.

  The surface of the image carrier is uniformly charged by a charging unit, and an exposure unit is operated based on the original or image data to form an electrostatic charge latent image (hereinafter simply referred to as a latent image) on the image carrier. Next, a color toner or a two-component developer containing a color toner and a carrier is guided to a development area, and the latent image is made into a color toner image by contact or non-contact development, and then the color toner image is intermediated. For example, yellow (Y), magenta (M), cyan (C), and black (BK) toners are transferred in this order to transfer each color toner image onto the intermediate transfer member. 2. Description of the Related Art Image forming apparatuses using an electrophotographic method are well known which are superposed on each other and then transferred onto a recording material made of plain paper and fixed on the recording material by heating and pressing by a fixing means.

  Also known is an image forming apparatus in which the intermediate transfer member is configured as an endless belt, and the above process is completed while the intermediate transfer member rotates once.

  The image forming apparatus as described above generally has a cleaning unit that cleans the surface of the image carrier after passing through the transfer region, and after passing through the transfer step for the recording material (in the image forming process, the image passes through the transfer region). It has a cleaning means for cleaning the surface of the intermediate transfer member.

  As the cleaning means, a cleaning means comprising a blade is generally used, and the blade is usually provided in a direction (counter direction) opposite to the rotation direction of the intermediate transfer member.

  On the other hand, the toner constituting the developer contains a base material made of pigment, wax, resin, etc., abrasive particles such as silica, titania, cerium oxide, and an external additive made of a lubricant.

  If such toner remains on the intermediate transfer body after passing through the transfer process during the image forming process, it is cleaned at the edge of a cleaning blade (hereinafter also simply referred to as a blade) and removed from the intermediate transfer body. A part of which adheres to the edge of the blade.

  Further, the removed toner, in other words, the adhering toner enters a gap between the edge portion of the blade (hereinafter sometimes referred to as blade edge or simply edge) and the intermediate transfer member, and if held there, The contained abrasive acts as a lubricant to lower the coefficient of friction between the two, and as a result, the occurrence of blade curl can be suppressed, and good cleaning can be achieved.

  However, it is difficult to maintain the toner existing between the blade edge and the intermediate transfer member for a long period of time, and the wax or lubricant contained in the residual toner partially adheres to the intermediate transfer member. Therefore, these waxes and lubricants are not successfully removed by the blade, but rather are stretched by the pressure of the blade to form a thin film (filming) in the traveling direction of the intermediate transfer member.

  The coefficient of friction between the part on the intermediate transfer member where such filming has occurred and the blade edge is larger than the coefficient of friction between the two parts in the part without filming. The edge part on the blade in contact was damaged, and in that part, the wax and the lubricant slipped more than before, and the occurrence of further filming was accelerated.

  The toner that can contribute to the cleaning function as described above needs to adhere to the blade edge. For example, the width of the intermediate transfer member capable of image formation (in terms of the maximum image width, Intermediate transfer body in which no image is formed when image formation is performed continuously or in large quantities with only half the width of the image (length in the direction orthogonal to the traveling direction of the intermediate transfer body) Only a small amount of toner comes to the blade edge corresponding to the upper portion in the width direction.

  Therefore, even if an appropriate amount of toner is initially accumulated at the edge portion of the blade having a length substantially equal to the image forming width, the toner at the edge portion of the blade corresponding to the non-image area is quickly depleted. As a result, the friction coefficient between the edge portion of the blade corresponding to the portion and the intermediate transfer member is increased, and as described above, the blade edge portion is damaged, and the wax or lubricant fills through the portion. Ming occurred.

  When such filming is formed on the intermediate transfer member, the resistance of the portion increases, and when the transfer process is performed, the transferability of the filming portion is deteriorated and white streaks are formed on the recording material. There is a problem that the image quality is deteriorated.

Although it is not a countermeasure for such a problem, in an image forming apparatus in which a color image is formed on an intermediate transfer member (intermediate transfer belt) and then transferred onto a recording material, an intermediate transfer is performed during continuous image formation. In order to suppress the phenomenon that the friction coefficient between the body and the cleaning blade rises and the blade is bent, for example, a toner image formed on one of the photosensitive drums is formed on the intermediate transfer body every predetermined number of image formations. An image forming apparatus configured to transfer and guide the toner image to a cleaning blade without transferring the toner image onto a recording material, thereby reducing friction between the cleaning blade and the intermediate transfer member and preventing the blade from curling due to an increase in friction. Has been proposed (see, for example, Patent Document 1).
JP 2002-244386 A (paragraph numbers 0051 to 0056)

  Although the technique disclosed in Patent Document 1 seems to be a useful technique as a measure for preventing blade sag, it does not consider the problem of filming.

  The present invention has been made in view of the above-described problems, and a main purpose thereof is to prevent the occurrence of filming on the intermediate transfer member as much as possible, and filming is formed on the intermediate transfer member. Even in such a case, it is an object of the present invention to provide an image forming apparatus in which the filming is easily removed, so that the formed image does not deteriorate.

  The object of the present invention can be achieved by the following constitution.

(1) having a plurality of image carriers and a plurality of developing devices each containing a developer containing color toner provided to form toner images of different colors on the respective image carriers; Then, after each color toner image formed on the image carrier is superposed on the intermediate transfer member, the image is transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is transferred to a blade. In an image forming apparatus configured to be cleaned by a cleaning unit comprising:
In addition to the normal color image forming mode, among the plurality of developing devices, a developing device including a toner having a small amount of lubricant added is operated, and the toner having a small amount of lubricant added is passed through the intermediate transfer member. An image forming apparatus having an adjustment mode for supplying to the blade.

  (2) The image forming apparatus according to (1), wherein the adjustment mode is selected from an operation panel.

(3) having a plurality of image carriers and a plurality of developing devices each containing a developer containing color toner, which are provided to form toner images of different colors on the respective image carriers. Then, after each color toner image formed on the image carrier is superposed on the intermediate transfer member, the image is transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is transferred to a blade. In an image forming apparatus configured to be cleaned by a cleaning unit comprising:
The surface state of the intermediate transfer member is detected by a detecting means, and a developing device including a toner having a small amount of lubricant added is operated among the plurality of developing devices according to the detection result. An image forming apparatus, wherein a small amount of toner is supplied to the blade via the intermediate transfer member.

(4) a plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner, provided to form toner images of different colors on the image carriers. Then, after each color toner image formed on the image carrier is superposed on the intermediate transfer member, the image is transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is transferred to a blade. In an image forming apparatus configured to be cleaned by a cleaning unit comprising:
When the number of image formation reaches a predetermined number, among the plurality of developing devices, a developing device including a toner with a small amount of lubricant added is operated, and the toner with a small amount of lubricant added is transferred to the intermediate transfer member. An image forming apparatus configured to be supplied to the blade through the image forming apparatus.

(5) a plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner, provided to form toner images of different colors on the respective image carriers. Then, after each color toner image formed on the image carrier is superposed on the intermediate transfer member, the image is transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is transferred to a blade. In an image forming apparatus configured to be cleaned by a cleaning unit comprising:
The current flowing through the motor that drives the intermediate transfer member is monitored, and when the torque value with respect to the current reaches a predetermined value, the developing device including toner with a small amount of lubricant added is operated among the plurality of developing devices. An image forming apparatus characterized in that a toner with a small amount of lubricant added is supplied to the blade via the intermediate transfer member.

  The image forming apparatus according to claim 1 operates a developing device including a toner having a small amount of lubricant added out of a plurality of developing devices, in addition to a normal color image forming mode, and the toner having a small amount of lubricant added. Has an adjustment mode for supplying to the blade via the intermediate transfer member, so that filming on the surface of the intermediate transfer member can be prevented as much as possible, and the maximum image width on the intermediate transfer member can be prevented. Since the toner can be supplied over the entire length of the blade corresponding to the above, curling of the edge portion of the blade can be suppressed.

  Since the image forming apparatus according to the second aspect is configured to select the adjustment mode from the operation panel, it can appropriately cope with a sudden change in environmental conditions and has good operability.

  The image forming apparatus according to claim 3 detects the surface state of the intermediate transfer member with a detecting means, and automatically sets the device to an adjustment mode according to the result, and the toner with a small amount of lubricant is added to the intermediate transfer member. Therefore, filming can be prevented, and toner can be supplied over the entire length of the blade corresponding to the maximum image width on the intermediate transfer member. Moreover, the edge part of a blade can also be suppressed.

  The image forming apparatus according to claim 4 automatically sets the apparatus to an adjustment mode when the number of formed images reaches a predetermined number, and supplies toner with a small amount of lubricant added to the blade via the intermediate transfer member. Therefore, the occurrence of filming can be prevented, and the toner can be supplied over the entire length of the blade corresponding to the maximum image width on the intermediate transfer member. Drowning can also be suppressed.

  In addition, for example, a recording material such as A4R or B4 is longitudinally fed with respect to the maximum image forming width on the intermediate transfer member (an aspect in which the long side of the recording material is placed in the recording material conveyance direction) The friction coefficient between the edge portion of the blade and the intermediate transfer member corresponding to the difference in the width direction (synonymous with the non-sheet passing portion) between the maximum image width and the sheet passing width of the recording material. As a result, the risk of blade edge curling can be prevented or suppressed.

  The image forming apparatus according to claim 5 measures or monitors the torque of the driving motor for the intermediate transfer member, and automatically turns the apparatus on when the torque reaches a set value or exceeds the set value. In the adjustment mode, toner with a small amount of lubricant added can be supplied to the blade through the intermediate transfer member, so that filming can be prevented and the maximum image on the intermediate transfer member can be prevented. Since the toner can be supplied over the entire length of the blade corresponding to the width, it is also possible to suppress the phenomenon of the edge portion of the blade.

  Further, the load on the motor based on the friction between the blade and the intermediate transfer member can be reduced as described above, and the speed of the intermediate transfer member during the execution of the image process can be maintained within an allowable range.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view showing a first embodiment of an image forming apparatus comprising a digital color copying machine according to the present invention.

  The image forming apparatus includes an automatic document feeder 1 at the top of the apparatus body, an image reading unit 2, an image forming unit 3, an installation unit of a belt unit 4 including a rotating belt as an intermediate transfer member, and a paper feeding unit 5. , A fixing device T, a reverse paper discharge / refeed unit 6, and an ADU 7 which is a reverse conveyance unit.

  The automatic document feeder 1 is a device that feeds documents one by one, conveys them to an image reading position, and discharges the document after image reading to a predetermined location.

  The automatic document feeder 1 includes a document placing table 101 on which a document is placed, a document separating unit 103 for separating the placed document, a document transporting unit 105 for transporting the separated document, and discharging the transported document. A pair of rollers used to reverse the front and back surfaces of the original in the double-sided copy mode for reading the images on both sides of the original. The document reversing means 111 is provided.

  In view of the processing process, a plurality of documents (not shown) placed on the document placing table 101 are separated one by one by the document separating means 103, and the image reading position is passed through the document conveying section 105. It is conveyed toward.

  The document reading position is provided at a lower portion of the document conveying unit 105, where an image of the document is read through the slit 201 constituting the image reading device 2, and the read document is discharged from the document. The sheet is discharged onto the document discharge table 109 by the means 107.

  In the double-sided copy mode, the original document that has been read and transported on one side is conveyed by the document reversing means 111 in the direction indicated by the two-dot chain line arrow, and the original document is being bitten at the trailing edge in the direction of travel. The reverse rotation after the driving of the reversing unit 111 is stopped and the image is again guided to the image reading position via the document conveying unit 105, and then discharged onto the document discharge table 109 by the document discharge unit 107. Is done.

  The above process is repeated for the number of documents placed on the document placing table 101.

  The image reading device 2 includes a first mirror unit 205 and a first mirror 215 that are formed by integrating the slit 201, a lamp 213 for irradiating a document, and a first mirror 215 that reflects reflected light from the document. A second mirror unit 207 in which a second mirror 217 that reflects light and a third mirror 219 are integrated in a substantially V shape, and an image that forms an image of reflected light from the third mirror 219 on the image sensor. A lens 209 and a line-shaped image sensor (hereinafter referred to as a CCD) 211 that photoelectrically converts a light image formed by the imaging lens 209 to obtain image information are included.

  The image information is temporarily stored in a memory (not shown) after appropriate image processing.

  In a mode in which the document fed by the automatic document feeder 1 is read by the image reading device 2, the first mirror unit 205 and the second mirror unit 207 are fixed at positions as shown.

  The image signals for the respective colors read by the image reading device 2 are sequentially taken out from the memory and inputted as electric signals to the respective exposure optical systems which are electrostatic charge latent image forming means.

  The image forming unit 3 forms four image forming units (hereinafter referred to as image forming units) of yellow (Y), magenta (M), cyan (C), and black (BK) that form a toner image corresponding to a color separation image. ) 30.

  Each of the image forming units 30 includes, for example, an image carrier (hereinafter referred to as a photosensitive drum) 310 in which a photosensitive layer made of a resin such as polycarbonate containing an organic photoconductor is provided on a drum-shaped metal substrate. A charger 320 of scorotron type, an exposure optical system 330 as image writing means, a developing device 8 for visualizing an electrostatic charge latent image, a transfer means (primary transfer means) 340, and the surface of the photosensitive drum 310 after transfer. A cleaning device 350 including a blade to be cleaned (cleaning means) is a main component.

  The developing device 8 incorporates a two-component developer containing a magnetic carrier (hereinafter simply referred to as carrier) and a non-magnetic toner (hereinafter simply referred to as toner), and is fixed in position and has a plurality of magnetic poles in the circumferential direction. And a developer carrying member (developing sleeve) having a rotatable and non-magnetic cylindrical shape incorporating a magnet in which the magnets are arranged.

  Since the basic configuration of the developing device 8 is well known, a detailed configuration is omitted.

  The exposure optical system 330 is an exposure unit composed of a laser optical system, and the transfer means 340 is opposed to a part of the peripheral surface of the photosensitive drum 310 with an intermediate transfer body 401 interposed therebetween.

  Since the mechanical configuration of the four sets of image forming units described above is basically the same, reference numerals are assigned only to one set of units, and the others are omitted.

  Each of the image forming units 30 is provided with a flat surface (a stretched surface) A of a loop-shaped rotating belt (hereinafter referred to as an intermediate transfer belt) 401 that constitutes the belt unit 4 and is long in the belt installation portion. Are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (BK) from above.

  The intermediate transfer belt 401, the support rollers 405, 406, 407, the backup roller 410, and the like that rotatably suspend the intermediate transfer belt constitute the belt unit 4.

  A secondary transfer unit including a transfer roller 510 is disposed so as to rotate while pressing the backup roller with the intermediate transfer belt 401 interposed therebetween.

  Reference numeral 415 denotes a blade for cleaning the surface of the intermediate transfer belt 401 that has passed through the transfer region (region where the secondary transfer unit is provided), and is installed in the counter direction with respect to the intermediate transfer belt 401, and at least during image processing. Is configured such that the edge portion contacts the surface of the intermediate transfer belt 401.

  The blade 415 has a length corresponding to the maximum image width formed on the intermediate transfer belt 401 (the length in the direction orthogonal to the traveling direction, for example, the size corresponding to the long side of B4). In addition, the edge is adjusted and held so as to contact the intermediate transfer belt with a uniform pressure in almost the entire range.

  Image formation by the configuration of the image forming unit 30 and the belt unit 4 is performed as follows.

  As the image forming process starts, the surface of the photosensitive drum 310 that rotates counterclockwise is charged to a predetermined polarity by the charger 320.

  Next, the exposure optical system 330 performs exposure corresponding to the first color signal, that is, the yellow (Y) image signal, and a latent image corresponding to the (Y) image is formed on the photosensitive drum 310. Is done.

  The latent image is reversely developed by contact or non-contact development with a developer in the developing device 8 and converted into a toner image of (Y), and then transferred onto the intermediate transfer belt 401 by the action of the transfer unit 340.

  Image formation with other color signals, which is sequentially started after a predetermined time from the start of image formation with the first color signal, is performed in the same manner as described above, and each image of magenta (M), cyan (C), and black (BK). Each of the toner images is sequentially transferred so as to overlap with the image area where the toner image (Y) is present, and a superimposed color toner image is formed on the intermediate transfer belt 401.

  On the other hand, the surface of the photosensitive drum 310 after completion of the transfer process is cleaned by the cleaning device 350, and preparations for new image formation are made.

  Note that the start timing of each image forming process with respect to the photosensitive drum 310 or the intermediate transfer belt 401 is one side of the intermediate transfer belt 401, in the present embodiment, and the intermediate transfer belt 401. A registration sensor 413 provided in a section from a position where the transfer roller 510 is located to a position where the first set (yellow) image forming unit is provided is provided on the intermediate transfer belt 401. For example, time is measured starting from when a reference mark formed using paint is detected, and the (Y), (M), (C), and (BK) processes are sequentially started every predetermined time. It is configured.

  The detection signal from the registration sensor 413 is taken in, the time is monitored, and control related to individual processes is performed by a control unit (control means) S including a computer.

  Next, the color toner image formed on the intermediate transfer belt is transferred to, for example, a recording material P (hereinafter, referred to as “paper” for convenience) made of plain paper, and is involved in the process until it is discharged out of the apparatus. The other configurations of the apparatus will be briefly described.

  At an appropriate timing corresponding to the image formation on the intermediate transfer belt 401, the paper P is fed by the paper feed rollers 503 (513, 523) positioned in the feeding sections 501 (511, 521) of the paper feed section 5, It is conveyed toward the registration roller 551.

  Thereafter, the sheet P is fed again so as to overlap with the color toner image area on the intermediate transfer belt 401 by resuming the rotation of the registration roller 551, and the backup roller 410 and the transfer roller in the secondary transfer unit. 510, the color toner image carried (formed) on the intermediate transfer belt 401 is transferred onto the sheet P while being pressed and nipped together with the intermediate transfer belt.

  In transferring, it is desirable that an appropriate transfer bias voltage is applied between the transfer roller 510 and the backup roller 410.

  The sheet P on which the toner image has been transferred is separated from the intermediate transfer belt 401 while being subjected to the action of a separation claw (not shown), and conveyed toward the fixing device T, for example.

  The fixing device T includes a fixing roller T1 having a built-in fixing heater and a pressure roller T2 that rotates while being pressed against the fixing roller. The color toner forming the image is heated and pressed by both rollers. It is melted and fixed on the paper P.

  The paper P after the fixing process by the fixing device T is completed is conveyed by a paper discharge roller 603 provided downstream thereof, and is discharged onto a paper discharge tray provided outside the apparatus main body.

  On the other hand, the surface of the intermediate transfer belt 401 after the completion of the secondary transfer is cleaned by a cleaning unit comprising a blade 415, and preparations for carrying a new toner image are made.

  The toner in each developer is consumed by the development process. This is because a toner concentration detection sensor is provided at an appropriate place in each developing device 8 and the inside of the developing device is based on information from the sensor. Toner is supplied to the printer, which can be handled by known techniques.

  In the figure, the solid line position of the path switching member 601 is a position held when the upper and lower surfaces of the paper P are reversed and discharged after the fixing process, and the broken line position is sent out from the fixing device as described above. This position is held when the sheet is discharged as it is.

  For example, in the reverse discharge of the paper P, the paper P sent out from the fixing device T is guided downward along the right side of the path switching member 601, and the rear end in the advancing direction is held by the roller pair 602. It is lifted by the reverse rotation of the roller pair 602 after being set in the closed state, passes through the left side of the switching member 601, reaches the paper discharge roller 603, and is discharged so as to be discharged by the paper discharge roller. Is done.

  Further, the behavior of the paper P in the double-sided copy mode using the ADU 7 is similar to that in the case of the reverse discharge. The paper P after the fixing process with the image formed on one side is moved along the right side of the switching member 601. Then, after stopping the conveyance with the trailing edge of the paper P in the traveling direction being nipped by the roller pair 605, the roller pair 605 is rotated in the reverse direction and is raised along the guide plate G, and a plurality of roller pairs The reversal of the paper P is achieved by leading to the ADU 7 having 701, 703, and 705.

  The image forming process for the second surface of the paper P is the same as described above, and any one of the above-mentioned is selected for the discharge after being sent out from the fixing device T.

  In the figure, reference numeral 250 denotes an operation panel at the upper part of the image reading device 2, and as is apparent from FIG. 2 which is a schematic plan view, the number of images formed (meaning the number of prints) is set. A switch unit (selection unit) 253 for switching the image mode from the normal image forming mode to the adjustment mode is included along with a numeric keypad 251 for starting and a start button 252 for starting recording. Reference numeral 255 denotes a liquid crystal display unit that can perform density setting, magnification setting, and the like, and is configured as a laminated display type touch panel.

  Here, the normal image forming mode is a mode in which the toner image formed on the photosensitive drum 310 is transferred and formed on the paper P via the intermediate transfer belt 401, and the adjustment mode is the photosensitive drum. A toner image or a toner pattern formed on the paper P by selectively using a predetermined developing device (a developing device including a toner to which a lubricant is added as an external additive and a small amount of the lubricant is added) is formed on the sheet P. A mode in which the toner is supplied to the blade 415 via the intermediate transfer belt without transferring.

  The toner as described above in the adjustment mode is supplied over the entire length of the blade, in other words, the width corresponding to the maximum image width on the intermediate transfer belt.

  When a predetermined toner is supplied to the blade by selecting the adjustment mode, most of the toner is cleaned by the blade and stored in a storage portion formed in the lower part of the cleaning device. It adheres to the edge, is held, and is pressed against the surface of the intermediate transfer belt.

  When the toner is pressed against the surface of the intermediate transfer belt, the cleaning performance of the belt surface is enhanced. Therefore, even when filming is formed on the intermediate transfer belt due to edge curling of the blade, for example. Therefore, the surface of the intermediate transfer belt can be maintained in a state where high-quality image formation is possible.

  Further, when the filming is not yet formed on the surface of the intermediate transfer belt, the adjustment mode is selected, and when the predetermined toner is supplied to the blade, the filming can be prevented or suppressed.

  Here, the developing device selected in the adjustment mode is a developing device that contains toner with a small amount of lubricant added as an external additive of the toner, and supplies such toner with less lubricant to the blade. Thus, it is possible to take a good countermeasure against filming as described above.

  That is, the external additive is usually observed with, for example, inorganic fine particles such as silica, titania, strontium titanate, cerium oxide, and alumina fine particles and a scanning electron microscope for the purpose of improving fluidity. Spherical organic fine particles having a number average primary particle size of 10 to 2000 nm, for example, homopolymers or copolymers such as styrene and methyl methacrylate can be added, and the polishing effect by these fine particles (abrasive particles) can be increased. By polishing the surface of the intermediate transfer belt using this, the above-described effects can be obtained.

  Further, for example, a lubricant such as zinc stearate or calcium stearate is added as an external additive.

  By providing the adjustment mode as described above, the adjustment mode can be executed appropriately by looking at the image to be printed out, and it is convenient because a quick response can be taken even if there is a problem on the image. Is good.

  For example, after creating a large amount of images with a width smaller than the maximum image width and then creating an image with the maximum image width, the friction coefficient between the blade edge and the intermediate transfer belt in the non-image area until then When the edge rises and the edge is wrinkled, the above-mentioned filming or the like is likely to occur, but an immediate response in such a case is possible.

  Even if edge blurring occurs, adverse effects related to filming can be suppressed by increasing the amount of toner supplied in the adjustment mode.

  The command accompanying the operation of the changeover switch 253 is preferentially processed. For example, if image formation is in progress when the command is issued, the image formation should be executed immediately after the image formation is completed. It is desirable that the control unit S can be controlled.

  Next, in the image forming apparatus having the basic configuration as shown in FIG. 1, a second embodiment according to the present invention will be described with reference to the schematic explanatory diagram of FIG.

  That is, in the traveling direction of the intermediate transfer belt 401, a detection unit 450 for detecting the surface state of the belt is installed at an appropriate position downstream of the transfer region for the paper P and upstream of the blade 415. The reflectance is converted into a voltage value (ST1) and compared with a reference value (threshold value) (ST2). When the threshold value is reached or exceeded, the control unit S is used. The mode is automatically switched to the adjustment mode (ST3).

  If the image formation is in progress, the adjustment mode is executed after the image formation is completed (ST4), and the toner formed on the photosensitive drum 310 as an image or pattern is transferred to the blade 415 via the intermediate transfer belt 401. Supply.

  During the adjustment mode, if the detection value (actually, the voltage value obtained by converting the output) by the detection means becomes less than the threshold value (ST5), the adjustment mode is terminated.

  From the formation of the toner image or toner pattern in the adjustment mode to the supply to the blade and the resulting effects are substantially the same as in the first embodiment.

  In the second embodiment, since the mode automatically shifts to the adjustment mode, the operability is improved.

  In addition, although the said detection means 450 integrates a light emission means and a light reception means, it is good also as a different body.

  Next, in the image forming apparatus having the basic configuration of FIG. 1, a third embodiment according to the present invention will be described with reference to the flowchart of FIG.

  The number of image formations is counted by the counter means (ST10), and it is judged whether or not the number of image formations is equal to or greater than a reference value (set value) (ST11). Is sent to the control unit (ST13), the adjustment mode is executed (ST14), and when the adjustment mode is completed, the counter is reset to prepare for the next adjustment mode.

  In this case, the reference value and the number of times of adjustment mode execution (meaning the number of toner supply times) can be determined by experiment, and may be stored in the ROM and read and used at the time of execution.

  The configuration of toner image or toner pattern formation to supply to the blade when executing the adjustment mode in the third embodiment is substantially the same as in the first embodiment, and the effects achieved are as follows. This is substantially the same as that of the second embodiment.

  Further, in the fourth embodiment according to the present invention, the support roller 407 is used as a drive roller for the intermediate transfer belt, and the current flowing through the drive motor mechanically coupled to the shaft of the support roller is monitored. When the torque value with respect to the current reaches or exceeds the predetermined value, the mode of the image forming apparatus is automatically switched to the adjustment mode, and the above-described process is often executed. As in each embodiment, the occurrence of filming is prevented as much as possible, the generated filming is removed, the blade is prevented from wrinkling, or even if the blade is slightly wrinkled, the image quality is reduced as much as possible. Can be suppressed.

  In the above, the width size of an image or pattern (solid image) created with toner with less lubricant is equal to or larger than the maximum image width, and the amount of toner supplied in the width direction of the blade is various. The optimum condition according to the specification can be obtained by experiment.

  Further, the correction of the toner density in the developer due to the consumption of the toner in the adjustment mode can be dealt with by using a known toner density control method.

  As each color toner for image formation, it is desirable to use a toner produced by a polymerization method, particularly a toner produced by an emulsion polymerization method in order to improve image quality and improve cleaning performance.

  The production process includes an emulsion polymerization process for preparing resin particles by emulsion polymerization, a salting out / fusion process for adding toner particles to the resin particle dispersion and then salting out / fusion to form toner particles, A washing step of filtering the obtained toner particles from water to remove the surfactant, a drying step of drying the obtained toner particles, and a crushing step of crushing the dried toner as necessary; It consists of an external additive addition step of adding an external additive.

  Regarding materials, examples of polymerizable monomers include aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, and monoolefin monomers. A radical polymerizable monomer such as a olefin monomer, a diolefin monomer, or a halogenated olefin monomer is an essential component, and an Odge hand crosslinking agent can be used if necessary.

  Further, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group can be used.

  Examples of the crosslinking agent for improving the properties of the toner include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate. Can be mentioned.

  The radical polymerization initiator can be appropriately used as long as it is water-soluble, and examples thereof include potassium persulfate, 4,4′-azobis-4-cyanovaleric acid and its salt, azobisisobutyramide dihydrochloride, and the like. It is done.

  Regarding surfactants, ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium polyoxyethylenebenzenesulfonate, etc.), sulfate salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, octyl). Sodium sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, etc.), polyethylene oxide, polypropylene oxide, Combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide De, esters of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, nonionic surfactants such as sorbitan esters can also be used.

  Examples of the colorant include inorganic pigments and organic pigments.

  As specific inorganic pigments, for example, carbon blacks such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powders such as magnetite and ferrite are also used.

  These inorganic pigments can be used alone or in combination as required.

  When used as a magnetic toner, the above-mentioned magnetite can be added.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  These organic pigments can be used alone or in combination as required.

  In addition to the above, an external additive can be added and used for the purpose of improving the fluidity or cleaning property of the toner.

  These external additives are not particularly limited, and various inorganic fine particles, organic fine particles or lubricants can be used.

  As the inorganic fine particles, conventionally known fine particles can be used. For example, silica, titania, strontium titanate, cerium oxide, alumina fine particles and the like can be preferably used.

  As the lubricant, for example, zinc stearate, calcium stearate, aluminum, copper, magnesium, calcium salt, oleic acid zinc, manganese, iron, copper, magnesium salt, palmitic acid zinc, copper, magnesium, Examples include salts of higher fatty acids such as salts of calcium, zinc of linoleic acid, salts of calcium and the like, zinc of ricinoleic acid, salts of calcium and the like.

  The addition amount or type of these external additives (additives) is determined in consideration of charging performance, environmental stability, durability, and the like. The amount of addition is usually different for each color toner.

  In the emulsion polymerization toner according to the present invention, zinc stearate is added as an external additive.

  The amount added to the toner was zero for magenta and cyan, 0.15% by weight for yellow, and 0.05% by weight for black.

  As the magnetic carrier, a resin-dispersed carrier is suitable, but known materials such as metals such as iron, ferrite, and magnetite can be used, and ferrite particles are used as the carrier according to the present invention.

Further, the intermediate transfer belt was configured as a seamless semiconductive resin belt (surface resistivity: 1 × 10 ¹¹ Ω / □, volume resistivity: 1 × 10 ⁸ Ω · cm) formed with polyimide resin as a main component.

  The blade is made of a rectangular urethane resin having a thickness of 2 mm, a width of 340 mm, and a free length (h): 9 mm. The blade is in a counter direction with respect to the intermediate transfer belt and with a corner edge that contacts the intermediate transfer belt. The formed angle (contact angle) was positioned as an acute angle.

  The contact angle is preferably in the range of 10 ° to 30 °, more preferably 15 ° to 20 °. If the contact angle is less than 10 °, uncleaned toner is generated. This is not preferable because the blade tip portion is likely to be moved in the same direction as the moving direction of the intermediate transfer belt from the counter direction.

  The above-mentioned free length (h) refers to the length from the front end of the holding part that holds one long side of the blade by the holding member to the other long side end of the blade.

  Further, the addition amount of the lubricant, the surface resistivity of the intermediate transfer belt, the blade size, the installation angle (contact angle), and the like can be appropriately determined according to various conditions.

(Example 1)
"Image forming device"
A color copying machine (made by improving the Konica 8050) having the configuration of FIG. 1 was used.

  The main conditions are as follows.

-Process speed (V): 220 mm / sec
Photosensitive drum: formed by applying a phthalocyanine pigment dispersed in polycarbonate as an organic semiconductor layer on a substrate with a diameter of 60 mm. Photoconductor layer thickness including charge transport layer 25μm
Exposure: Laser scanning system, semiconductor laser (LD) power 300μW
Development: Two-component development system Intermediate transfer belt: Seamless semiconductive resin belt (Material polyimide, surface resistivity 1 × 10 ¹¹ Ω / □, volume resistivity 1 × 10 ⁸ Ω · cm)
Intermediate transfer belt tension: 50N
Primary transfer means: Selects and applies a predetermined current value from a current value table in which a matrix is formed of a conductive foam roller having a diameter of 20 mm, temperature and humidity, and a counter.

Press of primary transfer means: 5N
Secondary transfer means: Consists of a roller that presses the intermediate transfer belt against a rotatable backup roller (the resistance values of the backup roller and the secondary transfer roller are both 1 × 10 ⁷ Ω).

    A predetermined current value is selected from a current value table in which a matrix is formed by temperature and humidity and a counter, and applied.

  Cleaning blade for intermediate transfer belt: made of urethane resin.

Free length 9mm, thickness 2mm, width 340mm, contact angle 17 degrees "Developer"
Carrier: Ferrite Toner: Polymerized toner (Y, M, C, BK) produced by emulsion polymerization method, average particle size 6.5 μm, in addition to silica and titania as external additives for the purpose of improving fluidity and cleaning properties Add zinc stearate as a lubricant.

Lubricant addition amount (0.15 mass% for yellow toner, zero for magenta toner and cyan toner, 0.05 mass% for black toner)
Using the image forming apparatus and developer configured as described above, A4 size paper P was laterally fed, and five sheets of continuous image formation was repeated.

  As the manuscript, a character chart having a printing rate of 5% for each color was used.

  In order to check for the occurrence of white stripes, an entire halftone image of A3 size (the image width is the long side length of A4 size and the long side length of A3 is the length in the belt traveling direction) every 10,000 copies. B, G, R, 3 colors BK, PWM 20%) were output in total.

Here, B image is magenta (M) toner and cyan (C) toner, G image is yellow (Y) toner and cyan (C) toner, R image is yellow (Y) toner and magenta (M) toner, three colors A BK image is produced by superimposing the three color toners of Y, M, and C, respectively.
The same output was performed immediately after toner supply in the adjustment mode described below, and the effect of toner supply was examined.

  In the adjustment mode, ten half-tone images (PWM 20%) of the entire A3 size with magenta toner and cyan toner are produced, and the secondary transfer means is released from pressure bonding, and the toner for forming the image is bladed. The whole amount was supplied. The supply amount per unit length in the width direction of the blade is about 0.3 g / cm.

The results are shown in Table 1.
(Example 2)
The same image forming apparatus as in Example 1 is used, and a belt surface detection sensor (diffuse reflection type, manufactured by Konica Electronics) is installed between the secondary transfer unit and the blade, and the reflectance of the belt surface without toner is measured. When the measured output value was outside the pre-measured range (2.5 volts or more), toner for M and C image formation described later was supplied to the blade. The detection frequency of the belt surface state was performed every specified number of sheets, here, every 500 copies.

  The belt surface detection sensor moves in the width direction of the intermediate transfer belt (80 mm / sec) and detects the surface state of the entire belt width.

  The developer and the copy form are the same as those in the first embodiment.

  That is, a test of 100,000 intermittent copies of 5 sheets was performed by repeating A4 size paper P and repeating continuous image formation of 5 sheets.

  As a manuscript, a character chart having a printing rate of 5% for each color is used.

  When the sensor detection result on the surface of the intermediate transfer belt exceeds 2.5 volts, the image forming mode is switched to the adjustment mode, and as in the case of the first embodiment, the entire halftone image with magenta and cyan toner ( 10 pieces each of PWM 20%) were produced, and the secondary transfer means was released from the pressure bonding, and the entire amount of toner for forming the image was supplied to the blade.

  The supply amount per unit length in the width direction of the blade is about 0.3 g / cm.

  Also, an A3-sized full-tone halftone image (B, G, R, 3 colors BK, PWM 20%) was output every 10,000 copies, and the occurrence of white streaks was examined.

The results are shown in Table 1.
(Example 3)
In an image forming mode in which a size smaller than the maximum image width on the intermediate transfer belt (corresponding to the long side of A4 size) is selected and used, the entire halftone image with magenta and cyan toner every 500 copies 10 pieces (PWM 20%) were produced, and the secondary transfer means was released from pressure bonding, and the toner for forming the image was supplied to the blade.

  The supply amount per unit length in the width direction of the blade is about 0.3 g / cm.

  For every 10,000 copies, ten A3-sized full-scale halftone images were produced with magenta and cyan toner, and the total amount of the toner was supplied to the blade.

  The developer and the copy form are substantially the same as those in the first embodiment.

  That is, a test of 100,000 copies of 5 sheets intermittently was performed by feeding A4 size paper P vertically and repeating the continuous image formation of 5 sheets.

  As a manuscript, a character chart having a printing rate of 5% for each color is used.

  Then, every 10,000 copies, an A3 size full-scale halftone image (B, G, R, three colors BK, PWM 20%) was output, and the occurrence of white streaks was examined.

The results are shown in Table 1.
Example 4
The motor current of the DC brushless motor that drives the intermediate transfer belt is monitored, and when the torque with respect to the current value exceeds a preset value (threshold or reference value, here 3 kg · cm), the adjustment mode is set. Ten full-tone images of magenta and cyan toner were prepared for each, and the secondary transfer means was released from pressure bonding, and the entire amount of toner for forming the image was supplied to the blade.

  In the running, a test of 100,000 copies of 5 sheets intermittently was performed by repeating A4 size paper P and repeating continuous image formation of 5 sheets.

  As the manuscript, a character chart having a printing rate of 5% for each color was used.

  The supply amount per unit length in the width direction of the blade is about 0.3 g / cm.

  Also, an A3-sized full-tone halftone image (B, G, R, 3 colors BK, PWM 20%) was output every 10,000 copies, and the occurrence of white streaks was examined.

The results are shown in Table 1.
(Comparative Example 1)
In addition to using the image forming apparatus and the developer listed in the examples, five sheets of A4 size paper were intermittently fed laterally, and five sheets of continuous image formation was repeated. However, there is no adjustment mode.

  As a manuscript, a character chart having a printing rate of 5% for each color is used.

  As a result of outputting an A3 size halftone image for every 10,000 copies and examining white streaks, a large number of white streaks were recognized as shown in Table 1.

Filming occurred at the same position on the intermediate transfer belt.
(Comparative Example 2)
This is a comparative example corresponding to Example 3, which uses the image forming apparatus and developer listed in the Example, and feeds A4 paper vertically, repeats the continuous image formation of 5 sheets, and intermittently copies 5 sheets of 100,000 copies. Tested.

  However, there is no adjustment mode. As a manuscript, a character chart having a printing rate of 5% for each color is used.

  As shown in Table 1, many white streaks and filming were observed at corresponding positions on the intermediate transfer belt.

  White streaks were particularly large and remarkably generated in non-sheet passing areas.

  As can be seen from Table 1, in Example 1, white streaks were found in the output image at the time of 20,000, 50,000, and 80,000 copies, but they were eliminated by supplying the toner in the adjustment mode, and the intermediate transfer belt The above streak-like filming could be eliminated, and an image with no deterioration in image quality could be obtained.

  In Examples 2 to 4, no white streak was observed in the output image.

  These mean that the presence of the adjustment mode is useful for preventing or suppressing the occurrence of filming, and also preventing or suppressing the occurrence of the blade curling (edge curling) phenomenon.

  Further, it has been investigated that even when some blade curl occurs, image quality deterioration can be suppressed by appropriately increasing the amount of toner supplied with a small amount of lubricant added depending on the degree of blade curl.

  These supplied toner amounts can be obtained experimentally and can be used for control.

  Further, in the above examples, the details of the composition and manufacturing method of each color toner of Y, M, C, and BK are omitted, but this is not directly related to the toner manufacturing method and composition. In short, paying attention to the fact that the amount of lubricant added as an external additive of the toner varies depending on the colorant, the effect based on the configuration that achieves the technical idea according to the present invention is maintained even if the composition changes. This is because it was recognized that there was an invention.

1 is a schematic view showing a first embodiment of an image forming apparatus comprising a digital color copying machine according to the present invention. It is a typical top view of an operation panel. It is typical explanatory drawing for demonstrating 2nd Embodiment concerning this invention. It is a flowchart for demonstrating 3rd Embodiment concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Image reading part 250 Operation panel 253 Switch means (selection means)
3 Image forming unit 401 Intermediate transfer member (intermediate transfer belt)
450 detection means 5 paper feed unit 6 reverse paper discharge / re-feed unit 8 developing device

Claims (5)

A plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner provided to form toner images of different colors on each of the image carriers, Each color toner image formed on the image carrier is superimposed on the intermediate transfer member, and then transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is cleaned with a blade. In an image forming apparatus configured to be cleaned by means,
In addition to the normal color image forming mode, among the plurality of developing devices, a developing device including a toner having a small amount of lubricant added is operated, and the toner having a small amount of lubricant added is passed through the intermediate transfer member. An image forming apparatus having an adjustment mode for supplying to the blade. The image forming apparatus according to claim 1, wherein the adjustment mode is selected from an operation panel. A plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner provided to form toner images of different colors on each of the image carriers, Each color toner image formed on the image carrier is superimposed on the intermediate transfer member, and then transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is cleaned with a blade. In an image forming apparatus configured to be cleaned by means,
The surface state of the intermediate transfer member is detected by a detecting means, and a developing device including a toner having a small amount of lubricant added is operated among the plurality of developing devices according to the detection result. An image forming apparatus, wherein a small amount of toner is supplied to the blade via the intermediate transfer member. A plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner provided to form toner images of different colors on each of the image carriers, Each color toner image formed on the image carrier is superimposed on the intermediate transfer member, and then transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is cleaned with a blade. In an image forming apparatus configured to be cleaned by means,
When the number of image formation reaches a predetermined number, among the plurality of developing devices, a developing device including a toner with a small amount of lubricant added is operated, and the toner with a small amount of lubricant added is transferred to the intermediate transfer member. An image forming apparatus configured to be supplied to the blade through the image forming apparatus. A plurality of image carriers, and a plurality of developing devices each containing a developer containing color toner provided to form toner images of different colors on each of the image carriers, Each color toner image formed on the image carrier is superimposed on the intermediate transfer member, and then transferred from the intermediate transfer member onto the recording material, and the intermediate transfer member after the transfer is cleaned with a blade. In an image forming apparatus configured to be cleaned by means,
The current flowing through the motor that drives the intermediate transfer member is monitored, and when the torque value with respect to the current reaches a predetermined value, the developing device including toner with a small amount of lubricant added is operated among the plurality of developing devices. An image forming apparatus characterized in that a toner with a small amount of lubricant added is supplied to the blade via the intermediate transfer member.

Images