JP2011064832A - Image forming device and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To complete printing, even if a photoreceptor can not be charged when monochrome printing is requested, using substitute colors without contacting or separating the photoreceptor and without stopping a machine. <P>SOLUTION: An image forming device includes: an image forming means comprising a plurality of rotatable photoreceptors corresponding to a plurality of preset colors, a charging means for charging the photoreceptors, a developing means for developing electrostatic latent images on the photoreceptors, and a primary transfer means for transferring toner images on the photoreceptors to transfer materials; and a high voltage applying means for applying a high voltage to the image forming means. The image forming device has: a charging abnormality detecting means for detecting charging abnormality of the charging means; and an image forming control means for forming an image corresponding to a request for printing using any of the image forming means among the image forming means corresponding to other colors than a monochrome while applying a bias to the image forming means so as not to move the monochrome toner if the charging abnormality is detected when the request for printing in any monochrome among the plurality of colors is issued. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus or the like, a photosensitive member is charged, and an electrostatic latent image is formed by irradiating the charged photosensitive member with laser light corresponding to image data. Also, by developing the formed electrostatic latent image, a toner image is formed on the photosensitive member, and the formed toner image is transferred to a transfer belt or the like and then transferred to a recording paper or the like. Form an image.

  In such an image forming process, for example, when an abnormality occurs in the charging unit, a solid image is printed and the image is lost regardless of exposure.

  However, for example, in any charging method of non-contact type scorotron charging or contact type roller charging, since the bias is applied to the rubber roller and the photosensitive member, the resistance value of the load is very high even in a normal state. high. Therefore, it is difficult to distinguish between a state where the output is separated from the load and a normal state. For this reason, generally, a charged high-voltage power supply does not have a detection function for detecting whether or not such output is in a state of being separated from the load.

  In such a configuration, the contact between the bias application unit and the photosensitive member is separated in the case of contact-type charging, or foreign matter enters between the bias application unit and the photosensitive member in the case of non-contact type charging. When an abnormality occurred, the abnormality could not be detected by the high-voltage power supply. Therefore, when the image forming operation is executed in a state where the photosensitive member is not charged, a solid image is always output regardless of exposure, and the image is lost.

  In particular, when an image defect occurs in an image forming apparatus having a FAX function, there is a problem that received data does not remain at hand.

  Therefore, conventionally, for example, a technique has been disclosed in which a solid image on a photoreceptor is detected and compared with image data to determine whether or not the image is abnormal (see, for example, Patent Document 1).

  However, in the conventional method described in Patent Document 1, for example, in an image forming apparatus, when a monochrome printing request is made, there is some abnormality in the charging portion of the requested color, and the photosensitive member cannot be charged. Even if an abnormal solid image can be detected, for example, the movement of the toner can only be prevented by a separation function that separates the bias applying unit and the photosensitive member. For this reason, in general, when a charging abnormality occurs in black that does not have a separation function, a solid image is always printed when the machine is operated, so the machine has to be stopped.

  The present invention has been made in view of the above points, and even when monochrome printing is requested, even if the photosensitive member cannot be charged, the substitution is performed without bringing the photosensitive member into contact with or separating from it and without stopping the machine. An object of the present invention is to provide an image forming apparatus and an image forming method for completing printing by using a printer.

  In order to achieve the above object, the present invention provides a plurality of rotatable photosensitive members corresponding to a plurality of preset colors, charging means for charging the photosensitive members, and an electrostatic latent image on the photosensitive member. A plurality of image forming units corresponding to the plurality of colors, and a high pressure that applies a high pressure to the plurality of image forming units; a developing unit that develops; a primary transfer unit that transfers a toner image on the photoconductor to a transfer material; An image forming apparatus including an applying unit, wherein a charging abnormality is detected by the charging abnormality detecting unit that detects charging abnormality of the charging unit, and a charging abnormality is detected by the charging abnormality detecting unit when a print request is made in any one of the plurality of colors. If detected, any one of the image forming means for the colors other than the single color while applying a bias to the image forming means by the high voltage applying means so as not to move the single color toner. Used, and having an image forming control means for forming an image corresponding to the print request.

  The present invention also provides a plurality of rotatable photoreceptors corresponding to a plurality of preset colors, a charging unit for charging the photoreceptors, a developing unit for developing an electrostatic latent image on the photoreceptors, An image comprising: a plurality of image forming units corresponding to the plurality of colors including a primary transfer unit configured to transfer a toner image on the photoconductor to a transfer material; and a high voltage applying unit configured to apply a high voltage to the plurality of image forming units. An image forming method executed in a forming apparatus, comprising: a charging abnormality detection procedure for detecting a charging abnormality of the charging unit; and a charging abnormality detection procedure according to the charging abnormality detection procedure at the time of a print request for any one of the plurality of colors. Is detected, while applying a bias to the image forming unit by the high-voltage applying unit so as not to move the single color toner, any one of the image forming units for other colors than the single color Using imaging means, and having an image forming control procedure for forming an image corresponding to the print request.

  According to the present invention, at the time of monochrome printing request, even when the photosensitive member cannot be charged, it is possible to complete printing using the substitute color without bringing the photosensitive member into contact and separation and without stopping the machine. It is.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. It is a figure which shows the structure of the image creation means which concerns on this embodiment. It is a high voltage bias application sequence diagram for each image forming means during normal printing. It is a high voltage bias application sequence diagram with respect to each image forming means when charging abnormality occurs according to the first embodiment. It is a figure which shows the flow of the flowchart in the case of performing color printing. It is a high voltage bias application sequence diagram with respect to each image forming means at the time of occurrence of charging abnormality according to the second embodiment. It is a figure which shows an example of the abnormality detection using the high voltage | pressure application means in 4th Embodiment. It is a figure which shows the flowchart which controls substitution color printing timing. It is a high voltage bias application sequence diagram for each image forming means in the case of controlling the substitution color printing timing. It is a figure which shows the flow of the flowchart including the determination process of whether to perform substitution color printing in the flowchart of FIG. 8 mentioned above.

<About the present invention>
In the present invention, for example, when a monochrome printing request is made, there is some abnormality in the charged portion constituting the image forming means, and even when the photosensitive member requested for printing cannot be charged, the image forming means requested for printing is provided. By continuing to apply the applied bias in the direction in which the toner does not move downstream in the image forming process, the toner of the image forming means is prevented from moving to the photosensitive member or the transfer belt, and the substituting printing with other colors is performed. Make it possible.

  Hereinafter, embodiments of the present invention will be described in detail.

<Image Forming Apparatus in Present Embodiment>
FIG. 1 shows a schematic configuration of an image forming apparatus according to the present embodiment. A tandem image forming apparatus will be described as the image forming apparatus according to the present embodiment. Here, an example is shown in which an AIO (All in One) cartridge is employed as the process cartridge.

  An image forming apparatus 100 shown in FIG. 1 includes an AIO cartridge 1 (1Bk (black), 1M (magenta), 1C (cyan), 1Y (yellow))) that is an image forming unit (electrophotographic process unit), and a transfer belt 2. Is provided.

  The AIO cartridge 1 (1Bk, 1M, 1C, 1Y) is disposed along the transfer belt 2. The transfer belt 2 rotates counterclockwise, and AIO cartridges 1Bk, 1M, 1C, and 1Y are arranged in this order from the upstream side in the rotation direction of the transfer belt 2.

  The plurality of AIO cartridges 1Bk, 1M, 1C, and 1Y have the same internal configuration except that the color of the toner image to be formed is different. The AIO cartridge 1Bk forms a black image, the AIO cartridge 1M forms a magenta image, the AIO cartridge 1C forms a cyan image, and the AIO cartridge 1Y forms a yellow image.

  In the following description, the AIO cartridge 1Bk will be described in detail. However, since the other AIO cartridges 1M, 1C, and 1Y are the same as the AIO cartridge 1Bk, each component of the AIO cartridges 1M, 1C, and 1Y is Instead of Bk attached to each component of the AIO cartridge 1Bk, symbols distinguished by M, C, and Y are displayed in the figure, and description thereof is omitted.

  The transfer belt 2 is an endless belt stretched around a secondary transfer driving roller 3 that is rotationally driven and a transfer belt tension roller 4. The secondary transfer drive roller 3 is driven to rotate by a drive motor (not shown). The drive motor, the secondary transfer drive roller 3, and the transfer belt tension roller 4 function as drive means for driving the transfer belt 2 to rotate.

  The AIO cartridge 1Bk includes a rotatable photoconductor 5Bk, a charger 6Bk disposed around the photoconductor 5Bk, a developing device 8Bk, and a cleaner blade 9Bk.

  The charger 6Bk as charging means uniformly charges the surface of the photoconductor 5Bk by applying AC and DC bias as charging bias from a high voltage power source.

  The exposure unit 7 is configured to irradiate laser beams 10Bk, 10M, 10C, and 10Y that are exposure lights corresponding to image colors formed by the AIO cartridges 1Bk, 1M, 1C, and 1Y. For example, when an image is formed, the outer peripheral surface of the photoconductor 5Bk is uniformly charged by the charger 6Bk in the dark, and is exposed by the laser beam 10Bk corresponding to the black image from the exposure unit 7, so that an electrostatic latent image is obtained. Is formed.

  The developing unit 8Bk as the developing means visualizes the electrostatic latent image formed on the photoconductor 5Bk with black toner by a predetermined developing bias supplied from a high voltage power source, and thereby, the image is formed on the photoconductor 5Bk. A black toner image is formed.

  Inside the transfer belt 2, primary transfer rollers 11Bk, 11M, 111C, and 11Y as primary transfer means are disposed through the transfer belt 2 at positions opposed to the respective photoreceptors 5Bk, 5M, 5C, and 5Y. The primary transfer rollers 11 </ b> Bk, 11 </ b> M, 11 </ b> C, and 11 </ b> Y are each applied with a temporary transfer bias by a high-voltage power supply, and transfer the toner images on the surfaces of the photoconductors 5 </ b> Bk, 5 </ b> M, 5 </ b> C, and 5Y to the surface of the transfer belt 2.

  For example, the toner image formed on the photoconductor 5Bk is transferred onto the transfer belt 2 by the primary transfer roller 11Bk at the primary transfer position where the photoconductor 5Bk and the transfer belt 2 are in contact with each other. An image with black toner is formed.

  After the transfer of the toner image is completed, the photoreceptor 5Bk wipes unnecessary toner remaining on the outer peripheral surface with the cleaner blade 9Bk, and then waits for the next image formation.

  In this way, the transfer belt 2 to which the black toner image is transferred in the AIO cartridge 1Bk is conveyed to the next AIO cartridge 1M when the transfer belt 2 is rotationally driven. In the AIO cartridge 1M, a magenta toner image is formed on the photoconductor 5M by a process similar to the image forming process in the AIO cartridge 1Bk, and the magenta toner image is a black toner image formed on the transfer belt 2. Is transferred in a superimposed manner.

  The transfer belt 2 is further conveyed to the next AIO cartridge 1C, 1Y, and a cyan toner image formed on the photoconductor 5C and a yellow toner image formed on the photoconductor 5Y are subjected to the same operation. Then, the image is transferred onto the transfer belt 2 in a superimposed manner. As a result, a full-color image is formed on the transfer belt 2. The transfer belt 2 on which the full-color superimposed image is formed is conveyed to the position of the secondary transfer roller 12.

  In the image formation, for example, in the case of printing only with black, the primary transfer roller 11M, the primary transfer roller 11C, and the primary transfer roller 11Y are retracted to positions separated from the photoreceptor 5M, the photoreceptor 5C, and the photoreceptor 5Y, respectively. The above-described image forming process is performed only for black.

  Further, the image forming apparatus 100 is configured to include a paper feed tray 13, a paper feed roller 14, a registration roller 15, a fixing device 16, and a paper discharge roller 17.

  During the paper transport operation during image formation, the paper P stored in the paper feed tray 13 is sequentially sent out by rotating the paper feed roller 14 counterclockwise and temporarily stands by at the position of the registration roller 15. The driving of the registration roller 15 is started at a timing when the toner image conveyed by the transfer belt 2 and the secondary transfer roller 12 overlap the position of the toner image and the paper P. The registration roller 15 feeds the paper P by being rotated counterclockwise.

  The toner image on the transfer belt 2 is transferred to the paper P sent out by the registration roller 15 by the secondary transfer roller 12, and the toner image transferred by the heat and pressure of the fixing device 16 is fixed on the paper P and counterclockwise. The paper is discharged to the outside of the image forming apparatus 100 by a paper discharge roller 17 driven to rotate around.

  When performing double-sided printing, the paper discharge roller 17 is driven to rotate clockwise before the paper P passes through the paper discharge roller 17, and the paper P is conveyed to the double-sided conveyance path. The sheet P transported to the duplex transport path is transported to the registration roller 15 again via the duplex roller 18. The paper P that has reached the registration roller 15 is fed again from the registration roller 15, and a toner image is transferred to the opposite side of the paper P by the secondary transfer roller 12. Is fixed and discharged to the outside of the image forming apparatus 100 by a discharge roller 17 driven to rotate counterclockwise.

  The image forming apparatus 100 includes a TM (toner mark) sensor 19 as a toner detection unit that is an example of a charging abnormality detection unit, and the TM sensor 19 is a toner mark formed outside the image area on the transfer belt 2. The toner amount is detected by detecting the pattern.

  In addition, the image forming apparatus 100 includes a control unit 20 as an image formation control unit and a high voltage application unit 30.

  The control unit 20 is realized by a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and controls the entire image forming apparatus 100.

  In addition, when the control unit 20 detects a charging abnormality based on information detected by the charging abnormality detection unit when, for example, there is a print request in any one of a plurality of colors set in advance by the user, While applying a bias to the image forming means by the high voltage applying means 30 in a direction not to move the single color toner requested to be printed downstream of the image forming means requested to print, the image forming means for other colors other than the single color An image corresponding to the print request is formed using any one of the image forming means.

  The image forming means includes, for example, a charger 6 for charging the photosensitive member 5, a developing unit 8 for developing the toner image formed on the photosensitive member 5 with a developer, and a toner image formed on the photosensitive member 5. It comprises a primary transfer roller 11 or the like that is transferred to a transfer material such as the transfer belt 2.

  For example, the control unit 20 applies a high-voltage bias to the developing unit 8 that has requested monochrome printing by using the high-voltage applying unit 30 that has a polarity opposite to that of the monochrome toner that requested printing. Further, the control means 20 applies tomorrow to the primary transfer roller 11 that has requested monochrome printing by the high-voltage applying means 30 when it has the same polarity as the monochrome toner that requested printing.

  As a result, even when the photosensitive member 5 cannot be charged when monochrome printing is requested, printing is completed using the substitute color without bringing the photosensitive member into and out of contact with the transfer belt 2 and without stopping the machine. It becomes possible to make it.

  The control means 20 is configured to have an image data holding means 21 as a storage means. The image data holding unit 21 holds image data for printing.

  The high voltage applying unit 30 applies a bias voltage to the charger 6, the developing unit 8, the primary transfer roller 11, and the like under the control of the control unit 20.

<Description of operation of image forming means>
Next, a normal operation in the image forming means of the AIO cartridge Bk will be described with reference to FIGS. FIG. 2 shows the configuration of the image forming means of the AIO cartridge Bk. FIG. 3 shows a high-voltage bias application sequence for each image forming means during normal printing.

  For example, a case where the polarity of toner is negative will be described. At this time, when developing the electrostatic latent image exposed by the laser beam 10Bk, a negative bias is applied to the developing device 8Bk.

  Here, at the start of printing, as shown in FIG. 3, first, for example, +100 V is applied as a bias having a positive polarity to the developing device 8Bk. That is, immediately after the start of the motor driving for rotating the photosensitive member 5Bk, the nip between the charging device 6Bk and the photosensitive member 5Bk indicated by the thick line D on the photosensitive member 5Bk shown in FIG. While the gap is in contact with the developing device 8Bk, a bias having a positive polarity is applied to the developing device 8Bk.

  This is because the negative charge on the photoconductor 5Bk applied by the charger 6Bk may be attenuated with time in the portion of the thick line D on the photoconductor 5Bk described above at the start of the first printing. is there. That is, although the photosensitive member 5Bk is not negatively charged, the negative polarity toner contacts the developing unit 8Bk uniformly distributed on the surface and moves to the photosensitive member 5Bk. This is to suppress the toner 8Bk by applying a force for holding the toner.

  In addition, before starting image formation for monochrome printing, for example, −1000 V is applied as a bias having a negative polarity to the charger 6Bk, and when starting image formation, for example, −350V is applied to the developing device 8Bk to charge the image. -1000V is continuously applied to the device 6Bk. Further, for example, +700 V is applied to the primary transfer roller 11Bk as a bias having a positive polarity. As a result, the black toner image formed on the photoconductor 5Bk is transferred onto the transfer belt 2.

  A positive bias is applied to the primary transfer roller 11Bk that contacts the photoconductor 5Bk via the transfer belt 2 in order to transfer the toner image formed on the photoconductor 5Bk to the transfer belt 2. Then, a negative bias is applied in order to return unnecessary toner remaining on the transfer belt 2 to the photoreceptor 5Bk for cleaning.

  As described above, the image forming operation described above is executed in each image forming unit during normal printing. However, if any abnormality occurs in the charger 6, the photoconductor 5 rotates without being charged and reaches the developing device 8, so that a solid image is printed regardless of the presence or absence of exposure. A method for solving this problem will be described below.

<First Embodiment>
First, the first embodiment will be described with reference to FIG. FIG. 4 shows a high-voltage bias application sequence for each image forming means when charging abnormality occurs according to the first embodiment.

  In the first embodiment, the control unit 20 immediately applies a bias having a polarity opposite to that of the toner, such as a positive polarity, to the developing unit 8 by the high voltage applying unit 30 when the charging unit 6 detects a charging abnormality. By continuing the operation, the toner is controlled to be held on the surface of the developing device 8. Thereby, the formation of a solid image on the photosensitive member 5 can be suppressed.

  Specifically, as shown in FIG. 4, when the control unit 20 detects a charging abnormality in the charging unit between the charger 6Bk and the photoconductor 5Bk after starting image formation with a single color (for example, Bk), Immediately, for example, +100 V is continuously applied as a bias having a positive polarity to the developing device 8Bk.

  Further, while performing the operation for suppressing the solid image formation on the photoconductor 5Bk as described above, the image data holding unit 21 holds the image using any image forming unit other than the image forming unit in which the charging abnormality has occurred. An image forming operation is performed based on the obtained image data.

  Specifically, as shown in FIG. 4, for example, an image forming operation is performed by an image forming means of magenta (M). That is, when detecting the charging abnormality of the charger 6Bk, the control unit 20 immediately applies, for example, + 100V as a bias having a positive polarity to the developing unit 8M, and for example, −1000V as a bias having a negative polarity to the charger 6M. Is applied and -350V is applied to the developing device 8M, for example, and -1000V is continuously applied to the charger 6M. Further, for example, +700 V is applied to the primary transfer roller 11M as a bias having a positive polarity. In this way, the image forming operation in the normal printing described above is performed by the magenta image forming means which is a substitute color. Thereby, image data can be printed without stopping the operation of the machine.

  As described above, according to the first embodiment, when the monochrome printing request is made, the control unit 20 has some abnormality in the charged portion of the image forming unit for which printing is requested, and the photosensitive member 5 cannot be charged. In this state, after the abnormality is detected in the charging abnormality detection means, a bias having a polarity opposite to that of the toner is continuously applied to the developing unit 8 constituting the image forming means, so that the machine operation is continued and uncharged. Toner adhesion to the photoreceptor 5 can be suppressed. In addition, it is possible to read out image data requested to be printed from the image data holding unit 21 and perform substitute color printing using any of the other colors.

<Flow of processing for substitute printing>
Next, with reference to FIG. 5, the flow of processing for performing substituting printing with magenta when a charging abnormality occurs between the charger 6Bk, which is a black (Bk) charging unit, and the photosensitive member 5Bk will be described. To do. FIG. 5 shows a flow of a flowchart in the case of performing substitute color printing.

  In FIG. 5, the time t1 is the time from the contact point A between the photoreceptor 5Bk and the developing device 8Bk in FIG. 1 to the contact point B between the photoreceptor 5M and the primary transfer roller 11M, for example. . The time t2 is, for example, the time from the point C where the laser beam 10M is irradiated onto the photoconductor 5M to the contact point B between the photoconductor 5M and the primary transfer roller 11M.

  First, as shown in FIG. 5, when a print request is received, the control unit 20 writes single-color print data into the image data holding unit 21 (S10), and determines whether an abnormality has occurred in the black charging unit. (S11).

  When it is determined that an abnormality has occurred in the black charging portion (YES in S11), the control means 20 applies a bias having a positive polarity to the developing device 8Bk (S12), and during the period from the detection of the abnormality to the start of exposure ( The system waits for time t1 to time t2) (S13). Further, the control unit 20 reads the monochrome print data from the image data holding unit 21 in order to print with the substitute color while waiting in the process of S13 (S14), and after the process of S13, the substitute color is obtained. For example, magenta exposure is started (S15).

  Next, when the magenta image formation is completed (S16), the paper discharge is completed (S17), and the data in the image data holding means 21 is erased (S18) as in the normal printing, and the process ends. If it is not determined that an abnormality has occurred in the black charging portion (NO in S11), normal printing is performed (S19), and the process ends.

  As described above, immediately after the print request, the image data holding unit 21 holds the print data requested to be printed, and continues to hold the data until it is confirmed that the paper discharge is completed. In addition, when an abnormality occurs in the charging unit, the control unit 20 reads out the data requested for printing from the image data holding unit 21 between the detection of the abnormality and the start of exposure (between time t1 and time t2). Start exposure with a substitute color. The data requested to be printed is erased after the completion of paper discharge is confirmed as in normal printing.

<Second Embodiment>
Next, a second embodiment will be described with reference to FIG. FIG. 6 shows a high-voltage bias application sequence for each image forming means when charging abnormality occurs according to the second embodiment.

  In the second embodiment, the control unit 20 immediately applies a bias having a negative polarity to the primary transfer roller 11 when the charging abnormality is detected by the charger 6, so that the toner is removed from the surface of the photoconductor 5. Control to hold. Thereby, formation of a solid image on the transfer belt 2 can be suppressed.

  Specifically, as shown in FIG. 6, when the control unit 20 detects a charging abnormality in a charged portion between the charger 6 </ b> Bk and the photoconductor 5 </ b> Bk after starting image formation with a single color (for example, Bk), Immediately, for example, −100 V is continuously applied to the primary transfer roller 11Bk as a bias having a negative polarity.

  Further, the control means 20 uses the image data holding means 21 by using any image forming means other than the image forming means in which charging abnormality has occurred while performing the operation for suppressing the solid image formation on the transfer belt 2. An image forming operation is performed based on the held image data.

  For example, as shown in FIG. 6, when the control unit 20 detects a charging abnormality of the charger 6Bk with respect to the photoconductor 5Bk, the controller 20 immediately applies, for example, -100 as a bias having a negative polarity to the primary transfer roller 11Bk and transfers the image. The formation of a solid image on the belt 2 is suppressed. On the other hand, in order to start image formation using the substitute color, for example, + 100V is applied as a bias having a positive polarity to the developing device 8M, and −1000V is applied as a bias having a negative polarity to the charger 6M. Further, when starting image formation with the substitute color, for example, -350V is applied to the developing device 8M, and -1000V is continuously applied to the charger 6M. Further, for example, +700 V is applied to the primary transfer roller 11M as a bias having a positive polarity. In this way, the image forming operation in the normal printing described above is performed by the magenta image forming means which is a substitute color. Thereby, image data can be printed without stopping the operation of the machine.

  As described above, according to the second embodiment, when the monochrome printing request is made, the control unit 20 does not provide any charge to the charged portion between the charger 6 and the photoconductor 5 constituting the image forming unit that has requested printing. In a state where there is an abnormality and charging of the photoconductor 5 is impossible, after the abnormality is detected by the charging abnormality detecting means, a bias having the same polarity as the toner is continuously applied to the primary transfer roller 11 constituting the image forming means. Thus, toner adhesion to the transfer material can be suppressed while the machine operation is continued. Further, the control unit 20 can read out image data requested to be printed from the image data holding unit 21 and perform substitution color printing using any of the other colors.

  It should be noted that a bias having a polarity opposite to that of the toner is continuously applied to the developing device 8 that has requested printing in the first embodiment, and the same polarity as that of the toner is applied to the primary transfer roller 11 that has requested printing in the second embodiment. By executing a combination in which a bias is continuously applied, it is possible to suppress toner adhesion to the uncharged photoconductor 5 while continuing the operation of the machine and to suppress toner adhesion to the transfer belt 2. .

<Third Embodiment>
In the third embodiment, the control unit 20 uses the TM sensor 19 as an example of a charging abnormality detection unit. More specifically, the TM sensor 19 is a sensor used for alignment and density adjustment of each color, and toner information attached on the transfer belt 2 by a toner mark pattern or the like formed on the transfer belt 2. Can be read.

  When an abnormality occurs in the charging portion, a solid image is formed at all locations where the photoconductor 5 including the outside of the image area and the transfer belt 2 are in contact with each other. Therefore, the control unit 20 uses the sensor. By acquiring toner information on the transfer belt 2 outside the image area, it is possible to detect charging abnormality.

  As described above, in the third embodiment, the control unit 20 detects the solid image on the transfer belt 2 by using the TM sensor 19 as the charging abnormality detection unit. When charging is abnormal, a solid image is formed at all locations where the photoconductor including the outside of the image area is in contact with the transfer belt. Therefore, the toner is transferred to the outside of the image area or the non-printing area using the TM sensor 19. By monitoring whether or not a solid image is present, it is possible to detect a solid image abnormality.

  In addition, for example, information obtained from a density sensor that detects the density of a toner image on a photoconductor disclosed in JP-A-2007-323000 and a toner image formed on the photoconductor based on image data are black solid. An abnormality of the solid image may be detected using a technique for determining whether the image is an abnormal image.

<Fourth Embodiment>
In the fourth embodiment, a high voltage application unit 30 having a charging abnormality detection unit is provided. The control unit 20 can detect an abnormality of the charging unit by monitoring the high voltage applying unit 30.

  FIG. 7 shows an example of abnormality detection using the high voltage applying means in the fourth embodiment. In the example of FIG. 7, the high voltage application unit 30 having the charging abnormality detection unit will be described.

  As shown in FIG. 7, the control means 20 is configured to include a control signal output unit 22 and a voltage monitoring unit 24. The high voltage applying means 30 is configured to have a control signal input unit 32, a booster drive unit 34, and a booster 36.

  In the above configuration, the control signal output unit 22 of the control unit 20 outputs a control signal to the control signal input unit 32 of the high voltage applying unit 30, and the control signal input unit 32 is a signal corresponding to the input control signal. Is output to the booster drive unit 34. The booster drive unit 34 drives the booster 36 based on a signal obtained from the control signal input unit 30.

  The booster 36 is driven from the primary side (low voltage) to the secondary side (high voltage) shown in FIG. 7 so as to boost the voltage from 24 V to about 1000 to 3000 V required for the charger 6 by the drive signal from the booster driver 34. ).

  Further, the booster 36 is controlled so as to output (feedback) information on the current (or voltage) flowing through the charger 6 to the booster drive unit 34 and keep the voltage (or current) constant by the booster drive unit 34. The

  Here, in the fourth embodiment, the voltage (voltage) flowing through the charger 6 is monitored by the voltage monitoring unit 24 of the control unit 20 by monitoring the voltage of the boosting unit driving unit 34 having a correlation with the high voltage output. It becomes possible to monitor the state of As a result, it is possible to detect the leakage state, which is an abnormal state of the charger 6, by the high voltage application means 30.

  As described above, in the fourth embodiment, a short detection unit mounted on a general high voltage power source is used as the charging abnormality detection unit. When the charger 6 is short-circuited, a high voltage is not applied to the charging roller and charging becomes defective, and a solid image is printed. Therefore, it is possible to detect a charging failure in the short mode at an initial stage by using the short detection means provided in the voltage monitoring unit 24.

<Fifth Embodiment>
Next, with reference to FIGS. 8 and 9, a timing control unit that controls the image forming timing of the substitute color printing when the print data to be substituted is spread over a plurality of sheets will be described. FIG. 8 shows a flow of a flowchart for controlling the substitute color printing timing. FIG. 9 shows a high-voltage bias application sequence for each image forming means when controlling the substitute color printing timing.

  The difference from the first embodiment to the fourth embodiment is that instead of executing substitution printing in the shortest time after the charging abnormality is detected, the control means 20 uses the timing control means to print data. This is the point of controlling the time until the substitution printing is executed according to the amount of printing.

  Specifically, as shown in FIG. 9, when the control unit 20 determines that an abnormality has occurred in the black (Bk) charging unit (YES in S20), the primary transfer roller 11Bk has a negative polarity. A bias is applied (S21), and then the control unit 20 determines whether or not the amount of print data requested for printing by the timing control unit covers a plurality of sheets (S22).

  When it is determined that the print data is not a plurality of sheets (NO in S22), the timing control unit performs the same processing as in FIG. 5 and waits from the time of abnormality detection to the start of exposure (time t1-time t2). (S23).

  On the other hand, when it is determined that the print data is a plurality of sheets (YES in S22), the timing control unit waits until the cleaning is completed (S24).

  Further, the timing control means starts magenta exposure after the above-described processing of S23 and S24 is completed (S25), completes magenta image formation (S26), and ends the processing.

  Here, the sequence of applying a high voltage bias to each image forming unit shown in FIG. 9 will be described. When the control unit 20 detects a charging abnormality of the charger 6Bk, the control unit 20 immediately sets a bias having a negative polarity to the primary transfer roller 11Bk. For example, -100 is applied to suppress the formation of a solid image on the transfer belt 2. On the other hand, after waiting for the belt cleaning of the transfer belt 2 to be completed, image formation by substitution is started. That is, when the belt cleaning of the transfer belt 2 is completed, for example, + 100V is applied as a bias having a positive polarity to the developing device 8M, and −1000V is applied as a bias having a negative polarity to the charger 6M.

  Further, when starting image formation with the primary color, as described above, for example, −350V is applied to the developing device 8M, and −1000V is continuously applied to the charging device 6M. Further, for example, +700 V is applied to the primary transfer roller 11M as a bias having a positive polarity. In this way, image data can be printed without stopping the operation of the machine by performing the above-described image forming operation in the normal printing by the magenta image forming means which is a substitute color.

  As described above, in the fifth embodiment, the timing control unit completely cleans the solid image written on the transfer belt 2 between the detection of the charging abnormality and the exposure, and then starts substitution printing. Therefore, it is possible to prevent background contamination due to the solid image of the substitute color print image.

  The timing control means determines whether or not the print data reaches a plurality of sheets because the print data to be subjected to the substitute color is not necessarily one sheet when executing the substitute color printing. When substituting printing is started immediately after the detection of charging abnormality when a plurality of substituting printings are performed, the charging belt 6Bk has already been formed on the transfer belt until charging abnormality is detected with respect to the photoconductor 5Bk. This is because the print data may overlap the solid image portion.

  At the time of execution of substitution printing, the solid image formed on the transfer belt 2 has once been passed through the transfer belt cleaning described in FIG. When the amount of toner is large as described above, the cleaning cannot be completed unless the cleaning is performed a plurality of times.

  Therefore, when the timing control unit determines that there are a plurality of substitute printings, the control unit 20 applies a bias having a polarity opposite to that of the toner to the developing unit 8Bk after the charging abnormality is detected, and immediately executes the substitute printing. Instead, the substitution printing is executed after the cleaning of the belt of the transfer belt 2 is completed. As a result, it is possible to output print data that is not soiled by the remaining toner of the solid image.

<Sixth Embodiment>
Next, with reference to FIG. 10, the execution determination means for determining whether or not to perform substitution printing will be described. FIG. 10 shows a flow of a flowchart including a determination process for determining whether or not substitute printing is performed in the flowchart of FIG. 8 described above.

  The difference from the first embodiment to the fifth embodiment is that the control means 20 determines whether or not to execute substitution printing by the execution determination means. The execution determination means determines whether or not execution is possible based on a preset “user's option”. Accordingly, for example, substitution printing can be set only for important data such as FAX reception data, and user convenience is improved.

  Specifically, as shown in FIG. 10, when the control unit 20 determines that an abnormality has occurred in the black (Bk) charging unit (YES in S30), the primary transfer roller 11Bk has a negative polarity. A bias is applied (S31), and then the control unit 20 determines whether or not substitute printing is to be performed by the execution determination unit based on preset setting information (S32).

  If it is determined that the substitute printing is to be executed (YES in S32), the execution determination unit determines whether the amount of print data requested for printing covers a plurality of sheets by the timing control unit as in FIG. (S33). If it is determined that the substitute printing is not to be executed (NO in S32), the execution determining unit stops the machine (S39) and ends the process. Note that the processing from S33 to S38 is the same as the processing from S22 to S27 in FIG.

  As described above, in the sixth embodiment, it is determined by the execution determination unit whether or not to execute substitute color printing. This is because, for example, in a composite image forming apparatus (not shown) having a FAX function, the received data does not remain after printing the FAX reception data on paper or the like. This is because of this.

  Therefore, when the primary color printing is executed, for example, as disclosed in Japanese Patent Laid-Open No. 2001-272888, when the toner density abnormality is detected, the output of the received data by the image forming means by the FAX application is stopped and the FAX is stopped. The data reception operation by the application is continued, and a decoding error occurs in the received FAX encoded data as disclosed in Japanese Patent Application Laid-Open No. 2006-019952, or a technique for storing the data received by the data reception operation in the storage means. In this case, until the print image is reliably printed using a technique for transmitting the encode data so that the encode data is decoded by another device, the print data is used using the image data holding unit 21 serving as a recording unit. Hold.

  Thus, according to the sixth embodiment, substitution printing is performed when the charging unit is abnormal, based on information set in advance by FAX data or printer data of the print request source, or an arbitrary setting value of the user. It is possible to select whether or not to implement.

  As described above, according to the embodiment of the present invention, when the monochrome printing request is made, the control unit 20 has some abnormality in the charged portion of the image forming unit for which the printing request has been made, and the photosensitive member 5 cannot be charged. Even in the state, by continuing to apply the bias applied to the image forming means in the direction in which the toner does not move downstream in the image forming process, it is possible to prevent the toner requested to be printed from moving to the photoreceptor 5 and the transfer belt 2. However, it is possible to perform substitute printing with other colors.

  Thus, even when the photosensitive member 2 cannot be charged when monochrome printing is requested, printing is completed using the substitute color without bringing the photosensitive member 2 into and out of contact and without stopping the machine.

The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. Is possible.

DESCRIPTION OF SYMBOLS 1 AIO cartridge 2 Transfer belt 3 Secondary transfer drive roller 4 Transfer belt tension roller 5 Photoreceptor 6 Charger 7 Exposure unit 8 Developer 9 Cleaner blade 10 Laser beam 11 Primary transfer roller 12 Secondary transfer roller 13 Main body paper feed tray 14 Paper feed roller 15 Registration roller 16 Fixing device 17 Paper discharge roller 18 Double-sided roller 19 TM sensor 20 Control unit 21 Image data holding unit 22 Control signal output unit 24 Voltage monitoring unit 30 High voltage application unit 32 Control signal input unit 34 Boost unit drive unit 36 Booster

JP 2007-323000 A

Claims (14)

A plurality of rotatable photosensitive members corresponding to a plurality of preset colors, a charging unit for charging the photosensitive member, a developing unit for developing an electrostatic latent image on the photosensitive member, and a toner on the photosensitive member An image forming apparatus comprising: a plurality of image forming units corresponding to the plurality of colors including a primary transfer unit that transfers an image to a transfer material; and a high voltage applying unit that applies a high voltage to the plurality of image forming units.
Charging abnormality detecting means for detecting charging abnormality of the charging means;
When a charging abnormality is detected by the charging abnormality detection unit at the time of printing request for any one of the plurality of colors, a bias is applied to the image forming unit by the high voltage applying unit so as not to move the single color toner. An image forming control unit configured to form an image corresponding to the print request by using any one of the image forming units for the colors other than the single color. Forming equipment. The image formation control means
2. The image forming apparatus according to claim 1, wherein a bias having a polarity opposite to that of the single color toner is applied to the developing unit corresponding to the single color by the high voltage applying unit. The image formation control means
The image forming apparatus according to claim 1, wherein a bias having the same polarity as that of the single color toner is applied to a primary transfer unit corresponding to the single color by the high voltage applying unit. The charging abnormality detection means has a toner detection means capable of detecting the amount of the toner at at least one location of the image forming means,
The image forming apparatus according to claim 1, wherein the charging abnormality is detected based on information obtained by the toner detection unit. The charging abnormality detection means includes
Monitoring means for monitoring the current or voltage applied to the charging means by the high voltage applying means;
The image forming apparatus according to claim 1, wherein the charging abnormality is detected based on information obtained by the monitoring unit. The image formation control means
The image forming apparatus according to claim 1, further comprising a timing control unit that starts image formation using any one of the image forming units for the other colors. . The image formation control means
7. An execution discriminating unit that discriminates whether or not to form an image corresponding to the print request by using any one of the image forming units for the other colors. The image forming apparatus according to any one of the above. A plurality of rotatable photosensitive members corresponding to a plurality of preset colors, a charging unit for charging the photosensitive member, a developing unit for developing an electrostatic latent image on the photosensitive member, and a toner on the photosensitive member The image forming apparatus includes a plurality of image forming units corresponding to the plurality of colors, each of which includes a primary transfer unit that transfers an image onto a transfer material, and a high voltage applying unit that applies a high voltage to the plurality of image forming units. An image forming method comprising:
Charging abnormality detection procedure for detecting charging abnormality of the charging means;
When an abnormal charging is detected by the abnormal charging detection procedure at the time of printing request for any one of the plurality of colors, a bias is applied to the image forming unit by the high voltage applying unit so as not to move the single color toner. And an image forming control procedure for forming an image corresponding to the print request by using any one of the image forming units for the colors other than the single color. Forming method. The image formation control procedure includes:
9. The image forming method according to claim 8, wherein a bias having a polarity opposite to that of the single color toner is applied to the developing unit corresponding to the single color by the high voltage applying unit. The image formation control procedure includes:
10. The image forming method according to claim 8, wherein a bias having the same polarity as that of the single color toner is applied to the primary transfer unit corresponding to the single color by the high voltage applying unit. 11. The charging abnormality detection procedure according to claim 8, wherein the charging abnormality is detected based on information obtained by a toner detection unit capable of detecting the amount of the toner at at least one location of the image forming unit. The image forming method according to claim 1. The charging abnormality detection procedure includes:
A monitoring procedure for monitoring the current or voltage applied to the charging means by the high voltage applying means;
The image forming method according to claim 8, wherein the charging abnormality is detected based on information obtained by the monitoring procedure. The image formation control procedure includes:
The image forming method according to claim 8, further comprising a timing control procedure for starting image formation using any one of the image forming units for the other colors. . The image formation control procedure includes:
14. An execution determination procedure for determining whether or not to form an image corresponding to the print request by using any one of the image forming units for the other colors. The image forming method according to any one of the above.

Images