JP2005266604A - Cleaning method for image forming apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method for an image forming apparatus in which a residual toner can be cleaned without requiring any special additional means even when an image carrier and a recording medium carrying belt deteriorate to change in characteristic or when temperature and humidity in the installation environment of the image forming apparatus change. <P>SOLUTION: A density measuring means measures background density of the recording medium carrying belt or image carrier and then a patch for density measurement is carried by the recording medium carrying belt or image carrier to measure the density of the patch; while a cleaning bias is varied, the patch is cleaned and the density of the remaining toner is measured and normalized with the background data to determine an optimum cleaning bias, thereby surely cleaning the remaining toner even when the image carrier and recording medium carrying belt deteriorate to change in characteristic or when the temperature and humidity in the installation environment of the image forming apparatus change. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and an image forming apparatus in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and in particular, an image carrier such as a photosensitive drum or an intermediate transfer belt. The present invention relates to a method of cleaning an image carrier and an image forming apparatus in an image forming apparatus including a cleaning device that transfers a toner image carried by a toner to a recording medium and then cleans the remaining toner while applying a cleaning bias.

  In an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, the surface of a photosensitive member (image carrier) is uniformly charged to a predetermined polarity, and light based on predetermined image information. Formation of an electrostatic image by irradiation (image exposure), formation of a toner image by development of the electrostatic image, transfer of the toner image to a recording medium such as paper, heating and pressurization by a fixing roller, and recording of the toner image Image formation is performed by an image forming process of fixing to a medium. After the transfer of the toner image to the recording medium, the toner remaining on the surface of the photosensitive member (image carrier) is cleaned and removed by a cleaning device, and further neutralized by light irradiation or the like as necessary. Prepared for the image forming process.

  Further, in such an image forming process, the toner image is not directly transferred to the recording medium, but once transferred to a belt or drum-shaped intermediate transfer member, and finally transferred from the intermediate transfer member onto the recording medium. An image forming apparatus that cleans the toner remaining on the intermediate transfer member with a cleaning device, or a toner image that is directly transferred from a photosensitive member (image carrier) to a recording medium conveyed by a recording medium conveying belt. Also in the image forming apparatus, the toner formed on the photosensitive member (image carrier) for adjusting the image density and transferred to the recording paper conveyance belt, or remains on the photosensitive member (image carrier) at the time of jamming and recorded. There is an image forming apparatus in which a cleaning device is used to remove toner transferred to a recording paper conveyance belt for some reason, such as being transferred to a paper conveyance belt.

  In such a cleaning device, a fur brush, a cleaning roller, a cleaning blade, and the like are used. In a cleaning device using a fur brush and a cleaning roller, a cleaning bias is applied to the fur brush and the cleaning roller to perform a cleaning effect. Has been done to increase. However, in such a configuration, a predetermined setting is not appropriate for the cleaning bias applied to the cleaning brush or the like due to the influence of temperature and humidity in the installation environment of the image forming apparatus and the variation of the resistance value of the intermediate transfer belt. In some cases, the image is smeared and the image may become dirty due to poor cleaning.

That is, for example, in a cleaning device that performs cleaning by applying a cleaning bias to a fur brush or a cleaning roller, as shown in FIG. 6, the horizontal axis represents the cleaning bias voltage applied to the cleaning device (the polarity is opposite to the charging polarity of the toner). ), when the vertical axis and cleaning amount, cleaning failure occurred and the cleaning bias voltage is, for example, less than V _1, is higher than V _2, turn its charging polarity by the cleaning electric field toner is too high is inverted cleaning Cause problems such as image smudges.

  For example, Patent Documents 1 to 3 are prior arts for dealing with such a situation. First, in Patent Document 1, when titanium oxide or the like is included in the toner as an abrasive, since the particle size of titanium oxide is smaller than that of the toner, it cannot be completely collected by the cleaning blade or the fur brush, and reaches the charging device to charge the roller. In some cases, charging abnormalities and discharge unevenness may occur, and there is a method of applying a bias to the image carrier and the cleaning member and using the electric field repulsive force against titanium oxide to recover, but apply a certain cleaning bias to the cleaning member. If this is continued, electric charges are gradually accumulated in the transfer residual toner due to an electric field, and a leak occurs between the excessively charged transfer residual toner and the image carrier. On the contrary, if the cleaning bias voltage is lowered, the abrasive cannot be sufficiently recovered. This is because the amount of residual toner and abrasive in the case of solid white is very small, while the amount of abrasive is relatively large, and in the case of solid black, the amount of residual toner is large. This is because the agent does not slip through and depends on the image density and is not constant, whereas the strength of the cleaning bias is constant.

  For this reason, Patent Document 1 discloses an image forming apparatus provided with density data detecting means for calculating density data in a predetermined range based on the number of dots in image data and the like, and controlling the cleaning bias based on the detected density data. ing.

  In Patent Document 2, since a color image forming apparatus requires stable color reproducibility, a density detection toner patch is formed on a transfer conveyance belt, and the density of the patch image is read by an optical sensor to process each color. Although the conditions are controlled, this patch cleaning means deteriorates in cleaning properties due to deterioration of the surface property of the transfer conveyor belt due to change over time, wear of the edge of the cleaning blade, etc. In this case, the back surface of the transfer material may be contaminated with toner due to a cleaning failure. Therefore, the transfer conveyance belt is rotated until the detection output of the density detection sensor relative to the transfer conveyance belt reaches a predetermined density. An image forming apparatus in which patches are cleaned by a cleaning device is shown.

  Patent Document 3 discloses a cleaning composed of a pre-cleaning charger for charging residual toner on a photoconductor with a corona, a cleaning sleeve having a magnet inside and carrying a magnetic carrier for cleaning as a magnetic brush. In the cleaning apparatus comprising the voltage applying means for applying a voltage to the cleaning means and the cleaning means, the charging of the photosensitive drum by the pre-cleaning charger shortens the life of the photosensitive member, so that the number of times of voltage application to the pre-cleaning charger is small. Although it is preferable to leave the pre-cleaning charger turned off, the charge amount of the remaining toner is reduced and the residual toner attracting force by the magnetic brush is weakened. Therefore, the voltage applied by the cleaning voltage applying means to the photosensitive drum Photoreceptor voltage to apply reverse polarity voltage Adding means, toner density detecting means for detecting the residual toner density on the photoconductor, and voltage application control means for controlling the voltage application of the photoconductor voltage applying means based on the residual toner density detected by the toner density detecting means. A cleaning device is shown which is provided and applies a cleaning voltage to the photosensitive drum during cleaning.

Japanese Patent Laid-Open No. 11-125938 JP 2001-142369 A Japanese Patent Laid-Open No. 3-7976

  However, the image forming apparatus disclosed in Patent Document 1 is provided with a density data detection unit that calculates the image density based on the number of dots in the image data, and the bias voltage applied to the cleaning unit based on the density data. Although determined, it has not been possible to deal with the occurrence of cleaning failure due to the change in the surface condition of the member to be cleaned over time, so that cleaning failure may occur.

  In the image forming apparatus disclosed in Patent Document 2, since the transfer conveyance belt is rotated until the detection output of the density detection sensor reaches a predetermined density, cleaning takes time and the density detection sensor output is If there is surface deterioration due to aging of the transfer / conveying belt, the output will naturally change, but there is no method to deal with such a situation, so there is a possibility that accurate density detection may not be possible. Defects may occur.

  The last cleaning device disclosed in Patent Document 3 is a cleaning device having a pre-cleaning charger and a cleaning sleeve that has a magnet inside and carries a magnetic carrier for cleaning by detecting the toner concentration of the transfer residual toner. Although it is controlled, it has not been confirmed whether or not the transfer residual toner has been completely cleaned. In this case as well, there is a possibility that a cleaning failure may occur.

  Therefore, in the present invention, no special additional means is required, and even if the characteristics of the image carrier or the recording medium transport belt deteriorate and the characteristics thereof change or the temperature and humidity in the installation environment of the image forming apparatus change, it is ensured. It is an object to provide a cleaning method and an image forming apparatus in an image forming apparatus capable of cleaning residual toner.

In order to solve the above problems, the cleaning method in the image forming apparatus of the present invention is:
A cleaning method in an image forming apparatus in which a toner image formed on an image carrier by an electrophotographic process is transferred, and then toner remaining on the image carrier is cleaned by a cleaning unit to which a bias voltage is applied,
It has a density measuring means for measuring the toner density of the toner image formed on the image carrier, and the background density when the toner image is not formed on the image carrier is measured by the toner density measuring means. A first step of forming a density measurement patch on the image carrier and cleaning while changing a bias voltage applied to the cleaning means; and cleaning in the second step. And a third step of measuring the toner density in the patch on the image carrier by the density measuring means, and the cleaning is performed based on the results measured in the first step, the second step, and the third step. Determining a bias voltage to be applied to the cleaning device, and applying the determined cleaning bias voltage to the cleaning device to perform cleaning. And wherein the Ukoto.

In addition, an image forming apparatus that performs this cleaning method is:
In an image forming apparatus for transferring a toner image formed on an image carrier by an electrophotographic process and cleaning the toner remaining on the image carrier by a cleaning unit to which a bias voltage is applied.
It has a density measuring means for measuring the toner density of the toner image formed on the image carrier, and the background density when the toner image is not formed on the image carrier is measured by the toner density measuring means. A first step of forming a density measurement patch on the image carrier and cleaning while changing a bias voltage applied to the cleaning means; and cleaning in the second step. And a third step of measuring the toner density in the patch on the image carrier by the density measuring means, and the cleaning is performed based on the results measured in the first step, the second step, and the third step. Determining a bias voltage to be applied to the cleaning device, and applying the determined cleaning bias voltage to the cleaning device to perform cleaning. And wherein the Ukoto.

Further, the cleaning method in the image forming apparatus of the present invention includes:
Image formation in which a toner image formed on an image carrier by an electrophotographic process is transferred to a recording medium conveyed by a recording medium conveyance belt, and the toner attached to the recording medium conveyance belt is cleaned by a cleaning unit to which a bias voltage is applied. A cleaning method in an apparatus,
A density measuring unit that measures a toner density of a toner image transferred to the recording medium conveyance belt; and a density measurement unit that measures a background density when no toner is transferred onto the recording medium conveyance belt. A second step of forming a density measurement patch on the image carrier, transferring the patch to the recording medium conveyance belt, and cleaning while changing a bias voltage applied to the cleaning unit; And a third step of measuring the residual toner density in the patch on the recording medium conveying belt cleaned in the step 2 by the density measuring means, the first step, the second step, and the third step, The bias voltage to be applied to the cleaning means is determined based on the result measured in step (b), and the determined cleaning via is determined. And performing cleaning by applying a voltage to said cleaning means.

In addition, an image forming apparatus that performs this cleaning method is:
Image formation in which a toner image formed on an image carrier by an electrophotographic process is transferred to a recording medium conveyed by a recording medium conveyance belt, and the toner attached to the recording medium conveyance belt is cleaned by a cleaning unit to which a bias voltage is applied. In the device
A density measuring unit that measures a toner density of a toner image transferred to the recording medium conveyance belt; and a density measurement unit that measures a background density when no toner is transferred onto the recording medium conveyance belt. A second step of forming a density measurement patch on the image carrier, transferring the patch to the recording medium conveyance belt, and cleaning while changing a bias voltage applied to the cleaning unit; And a third step of measuring the residual toner density in the patch on the recording medium conveying belt cleaned in the step 2 by the density measuring means, the first step, the second step, and the third step, The bias voltage to be applied to the cleaning means is determined based on the result measured in step (b), and the determined cleaning via is determined. And performing cleaning by applying a voltage to said cleaning means.

  Further, after the density measurement patch is formed on the image carrier or the recording medium conveyance belt, the toner density of the density measurement patch is measured by the density measurement unit before the density measurement patch is cleaned. And

  The toner density measurement hand throw is an image density control sensor in the image forming apparatus.

  And storing means for storing the cleaning bias corresponding to the toner density measuring means output in the third step, normalizing the measurement result in the third step with the measurement result in the first step, and normalizing the result. The cleaning bias stored in the storage means is read out according to the result, and the cleaning bias is changed.

  The image forming apparatus is provided with a manual button for performing the first to third steps, and the manual button is used to execute the first to third steps at an arbitrary time to determine the bias voltage of the cleaning unit. It is characterized by doing.

  Thus, there is provided density measuring means for measuring the toner density of the toner image transferred to the recording medium conveyance belt or the toner density of the toner image on the image carrier, and the toner is not transferred to the recording medium conveyance belt. A first step of measuring the background density with the density measuring means in a state where no toner image is formed on the image carrier, and forming the density measurement patch on the image carrier and performing the cleaning. A second step of cleaning while changing the bias voltage applied to the means, and the density measuring means measures the residual toner density in the recording medium transport belt or the patch on the image carrier cleaned in the second step. Based on the results measured in the third step, the first step, the second step, and the third step. Even if the image carrier or the recording medium transport belt deteriorates by determining the bias voltage of the cleaning means and performing cleaning by applying the determined cleaning bias voltage to the cleaning means, these recordings are performed in the first step. Since the background of the medium conveying belt or the image carrier is measured, the residual toner density measured in the third step can be accurately grasped based on the measurement result, and the amount of transferred residual toner and the charge It is possible to provide a cleaning method and an image forming apparatus in an image forming apparatus that can reliably clean residual toner even when the amount changes.

  Further, after the density measurement patch is formed on the image carrier or on the recording medium conveyance belt, before the density measurement patch is cleaned, the toner density of the density measurement patch is measured by the density measurement unit, It is possible to provide a cleaning method and an image forming apparatus that can confirm whether or not the density measurement patch has been formed normally and can accurately determine the cleaning bias.

  Then, the toner density measurement hand throw uses the sensor for controlling the image density in the image forming apparatus, so that the present invention can be carried out without using any special additional means or complicated mechanism for cleaning as in the prior art. it can.

  And storing means for storing the cleaning bias corresponding to the output of the toner density measuring means, normalizing the measurement results of the second and third steps with the measurement results of the first step, and normalizing the normalized results. By reading out the cleaning bias stored in the storage means according to the result and changing the cleaning bias, it is possible to always grasp the accurate amount of remaining toner and perform cleaning.

  Further, by providing the image forming apparatus with a manual button for performing the first to third steps, cleaning can be performed at an arbitrary time by using the manual button. Therefore, a user-friendly cleaning method in the image forming apparatus can be provided. .

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a block diagram schematically illustrating an example of an image forming apparatus that performs a cleaning method in the image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating an example of a schematic layer configuration of an intermediate transfer belt. 4 is a flowchart of the first and second embodiments of the cleaning method in the image forming apparatus according to the present invention, and FIG. 5 is a configuration diagram of the toner concentration measuring apparatus used in the cleaning method in the image forming apparatus of the present invention.

1 and 2, reference numerals 1 ₁ , 1 ₂ , 1 ₃ , and 1 ₄ denote photosensitive members (image carriers) formed in a drum shape, 2 denotes an intermediate transfer belt as an image carrier, 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ are charging devices such as scorotron, etc. 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ are exposure by an exposure device not shown, 5 ₁ , 5 ₂ , 5 ₃ , 5 ₄ are used in a color image forming apparatus The developing devices provided for each color such as black (B), magenta (M), cyan (C), yellow (Y), etc., 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ are cleaning devices. Various types of cleaning devices can be used such as a cleaning roller, a method using a brush such as a fur brush or a magnetic brush. 7 ₁ , 7 ₂ , 7 ₃ , 7 ₄ are static eliminators, 8 ₁ , 8 ₂ , 8 ₃ , 8 ₄ are primary transfer rollers, 10 is a reinforcing resin layer for the intermediate transfer belt 2, 11 is also an elastic substrate, 12 Is a fluororesin-containing surface layer, 13 is a control device for the entire image forming apparatus, 14 is an exposure control device for instructing exposure using image data 15 separated for each color sent via the control device 13, and 16 is The primary transfer bias applied to the primary transfer rollers 8 ₁ , 8 ₂ , 8 ₃ , and 8 ₄ , the power source of the secondary transfer bias applied to the secondary transfer roller 25, 17 is its control device, and 18 is the cleaning of the intermediate transfer belt. A control device including a cleaning bias power source to be applied to the brush, 21 and 22 are a driving roller and a driven roller of the intermediate transfer belt 2, 23 is a backup roller, 24 is a bias voltage, and intermediate transfer belt A cleaning roller for cleaning toner remaining on the belt, a cleaning device constituted by a cleaning brush such as a fur brush or a magnetic brush, 25 a secondary transfer roller, 26 a fixing device, 27 a recording medium, and 28 shown in FIG. A density sensor 30 for measuring the toner density, a cleaning bias storage device 30 for storing a cleaning bias corresponding to the residual toner density on the intermediate transfer belt 2 measured by the density sensor 28, and 31 for intermediate transfer. A background data storage device 33 for storing the reflection density of the intermediate transfer belt 2 itself when toner is not transferred onto the belt 2 is a manual button for carrying out the cleaning method of the present invention at an arbitrary time.

  In FIG. 5, 50 is a toner, 51 is a light emitting element using an LED or the like, 52 is light from the light emitting element 51 in the direction of the intermediate transfer belt 2, and the amount of light emitted from the light emitting element 51 is detected, and the amount of light is constant by a feedback circuit. A beam splitter 54 for directing the light in the direction of the light receiving element 53 for monitoring to maintain the light, and a beam splitter 54 for dividing the light reflected by the intermediate transfer belt 2 into the light receiving element 55 and the light receiving element 56.

  In the following description, a tandem type color image in which the electrophotographic process corresponding to each color is arranged in the transport direction of the intermediate transfer belt 2, is overlaid on the intermediate transfer belt 2, and is then transferred to a recording medium. The present invention will be described with reference to an example in which the present invention is applied to an image forming apparatus. However, the present invention relates to an intermediate transfer body as an image carrier such as an intermediate transfer belt and an intermediate transfer drum, a recording medium conveyance belt for conveying a recording medium, and a photosensitive drum. Any image forming apparatus having a cleaning device of a type that cleans residual toner remaining on an image carrier such as a photosensitive belt by applying a bias voltage and a toner concentration measuring device that detects the residual toner concentration The present invention can also be applied to an image forming apparatus of such a format. The present invention is not limited to the tandem type color image forming apparatus as shown in FIG. 1, and is a type of full color in which a plurality of developing devices filled with toner of each color are arranged around one photosensitive drum. It can also be applied to an image forming apparatus.

With initial reference to Figure 1, briefly described tandem image forming apparatus according to the present invention, 1 _{1, 1} 2, _{1 3,} 1 ₄ of the photosensitive member (image bearing member) is used in a color image forming apparatus for example black (B), magenta (M), cyan (C), respectively corresponding to yellow (Y), each of the photosensitive member (image bearing _member) 1 _1, 1 _2, 1 3, around _{1 4} Are provided with electrophotographic process members such as a charging device 3, an exposure device 4, a developing device 5, a cleaning device 6, and a static eliminator 7, and primary transfer rollers 8 ₁ , 8 ₂ , sandwiching the intermediate transfer belt ₂ . 8 ₃ and 8 ₄ are arranged, respectively.

The intermediate transfer belt 2 as an image carrier is stretched between a pair of driving and driven rollers 21 and 22 and a backup roller 23, and the intermediate transfer belt 2 is in contact with the intermediate transfer belt 2. Thus, the photoreceptors 1 ₁ , 1 ₂ , 1 ₃ , and ₄ , which are image carriers corresponding to the black (B), magenta (M), cyan (C), and yellow (Y), are transferred to the intermediate transfer belt 2. Further, a density sensor 28 is provided opposite to the intermediate transfer belt 2 to measure the toner density on the intermediate transfer belt 2, and the charging voltage of the charging device 3 is determined according to the measurement result. The toner density is kept constant by adjusting the developing bias of the developing device 5.

  In a toner container (not shown) in the developing device 5 arranged around each photoconductor 1, black (B) toner, magenta (M) toner, cyan (C) toner, and yellow (Y) are respectively provided. The toner images of the respective colors are formed by a known electrophotographic method. In other words, when each photosensitive member 1 is uniformly charged to a predetermined polarity by the charging device 3 and is exposed 4 with light based on the image data 15 separated for each color by the control device 13, the potential of the light irradiating portion is increased. By lowering, an electrostatic latent image is formed. The toner of each color supplied by the developing device 5 under a predetermined developing bias adheres to the formed electrostatic latent image portion (potential drop portion), and a toner image is formed.

Each color toner image formed on each photoconductor 1 in this manner is applied with a primary transfer bias potential (a polarity opposite to the toner charging polarity) applied by a transfer bias power supply 16 controlled by a transfer bias controller 17. Further, the primary transfer rollers 8 ₁ , 8 ₂ , 8 ₃ , and 8 ₄ sequentially transfer onto the intermediate transfer belt 2 that is driven in the direction of the arrow in FIG. The full-color toner image is further transferred to the recording medium 27 conveyed between the secondary transfer roller 25 and the backup roller 23, and the secondary image having a polarity opposite to that of the toner image applied from the transfer bias power source 16 to the secondary transfer roller 25. The recording medium is transferred with the transfer bias, and the recording medium is further sent to the fixing device 26 to fix the toner image.

The toner remaining without being primarily transferred from the photoreceptors 1 ₁ , 1 ₂ , 1 ₃ , and 1 ₄ to the intermediate transfer belt 2 is removed by the cleaning devices 6 ₁ , 6 ₂ , 6 ₃ , and 6 ₄ . At the same time, the charge remaining by the charge eliminators 7 ₁ , 7 ₂ , 7 ₃ , and 7 ₄ is discharged, and the toner remaining on the intermediate transfer belt 2 after the secondary transfer is cleaned by the cleaning device 24 to be the next image. Prepared for formation.

Among these, the intermediate transfer belt 2 that is an intermediate transfer belt has a belt-like elastic base 11 and a fluororesin-containing surface layer 12 provided on the surface, as shown in FIG. On the opposite side of the belt-shaped elastic substrate 11 from the fluororesin-containing surface layer 12, a reinforcing resin layer 10 is provided. By providing such a reinforcing resin layer 10, it is possible to effectively prevent transfer misalignment due to expansion and contraction of the elastic substrate 11. The reinforcing resin layer 10 and the elastic substrate 11 have a volume resistance of about 10 ^8.5 to 10 ^11.5 Ω · cm, particularly about 10 ⁹ to 10 ¹¹ Ω · cm, for effective transfer. Further, the thickness is preferably in the range of 80 to 100 μm.

  In the image forming apparatus described above, the primary transfer roller 8 and the secondary transfer roller 25 are made of conductive rubber such as foamed EPDM, and the cleaning device 24 is a cleaning roller, a fur brush, a magnetic brush, or the like. Can also be used.

  The density sensor 28 detects, for example, the image density of a toner image formed on the photosensitive member (image carrier) 1 and transferred to the intermediate transfer belt 2, and corrects the image density to an appropriate value. A reflection type sensor used for reading a color registration pattern for accurately aligning images of respective colors in an image forming apparatus and correcting misalignment, and has a configuration as shown in FIG.

  Light emitted from the light emitting element 51 using an LED or the like in the figure is detected by the beam splitter 52 to detect the direction of the intermediate transfer belt 2 and the light emission amount of the light emitting element 51, and to keep the light quantity constant by a feedback circuit. The light is divided into light directed to the monitor light receiving element 53. The light reflected by the intermediate transfer belt 2 on which the toner 50 is placed is divided into two polarization components of the light receiving element 55 and the light receiving element 56 by the beam splitter 54, and the toner density on the intermediate transfer belt 2 is determined by the ratio. Detected.

  Next, a first embodiment of the cleaning method in the image forming apparatus of the present invention will be described with reference to the flowchart shown in FIG. First, the cleaning method of the present invention will be briefly described. The cleaning method in the image forming apparatus of the present invention is provided opposite to the intermediate transfer belt 2 as an image carrier and applies a bias voltage to clean the toner. The bias voltage in the cleaning device 24 is set at (1) density adjustment to the intermediate transfer belt 2 at a predetermined time during non-image formation such as when the image forming device is turned on or when returning from the sleep mode for energy saving. (2) Cleaning the patch while changing the cleaning bias applied to the cleaning device 24, (3) Measuring the toner density remaining by the cleaning with a density sensor, (4) Cleaning bias depending on the measurement result Adjusting the voltage to the optimum voltage for cleaning Determining Te is it that so as to clean the.

  Therefore, in the present invention, the control device 13 first starts the density sensor 28 in step S2 of FIG. 3 at a predetermined time during non-image formation, such as when the image forming apparatus is powered on or when returning from the sleep mode for energy saving. The intermediate transfer belt 2 as an image carrier is measured as a background when there is no toner, and is stored in the background data storage device 31. As described above, the intermediate transfer belt 2 includes the elastic substrate 11 and the fluororesin-containing surface layer 12 provided on the surface, and the surface thereof is smooth. However, the reflection density is not always constant, and the secular change is also caused. Because the surface state changes depending on the case, even if the same amount of toner is loaded, the same reflection density may not be obtained. Thus, by measuring and storing the background, when measuring the toner density, An accurate toner density can be calculated by offsetting and normalizing the background density.

The control unit 13, the image bearing member ₁ 1 in the next step _S3, 1 _2, 1 3, _{1 4,} respectively, a solid toner patches for density measurement example (100%) exposure control device to form a 14 The exposure control device 14 performs exposure in accordance with the instructions to form latent images on the image carriers 1 ₁ , 1 ₂ , 1 ₃ , 1 ₄ . Then transfer the latent image to be developed by each of the image bearing member _{1 1,} 1 _2, 1 3, _{1 4} developing device provided in the _{5 1,} 5 _2, 5 3, _{5 4,} sent from a transfer bias power source 16 The image is transferred to the intermediate transfer belt 2 in the next step S4 by the primary transfer rollers 8 ₁ , 8 ₂ , 8 ₃ and 8 ₄ to which a bias is applied.

  Then, the control device 13 instructs the sensor drive circuit 19, reads the density of each patch in step S5, normalizes the patch density by subtracting the background data from the patch density, and determines whether the patch density is equal to or higher than the standard value in step S6. If it is checked and falls below the standard value, the process returns to step S3 again to optimize the developing bias so that the density of the patch image is equal to or higher than the standard value, thereby forming a patch image. Subsequently, in step S7, the control device 13 instructs the transfer bias power source 16 to set the potential of the secondary transfer roller 25 to the ground potential (0 V) so as not to change the charge of the toner on the intermediate transfer belt 2. Then, the toner on the intermediate transfer belt 2 passes through the secondary transfer roller 25 as it is and is sent to the cleaning device 24.

  Further, the control device 13 instructs the cleaning bias control device 18 in the next step S8 to perform cleaning while changing the cleaning bias to, for example, 500, 550, 600,... 1000 (V). This cleaning is preferably performed while changing the intermediate transfer belt 2 on which the patch is formed once. Otherwise, the toner cleaned with a cleaning bias that is not suitable for cleaning will remain on the intermediate transfer belt 2 in sequence, which may hinder the determination of the optimum cleaning bias.

  When cleaning is performed while changing the cleaning bias in this way, a difference occurs in the cleaning level, and a difference occurs in the density data after cleaning. Therefore, the control device 13 instructs the sensor drive circuit 19 in the next step S9 to measure the density of the remaining toner, and calculates the value together with the background data previously stored in the background data storage device 31. The data is sent to the apparatus 20, and the background data is subtracted from the residual toner density and normalized. Then, an actual cleaning situation is calculated by comparing the obtained values, and a cleaning bias corresponding to the residual toner density on the intermediate transfer belt 2 stored in the cleaning bias storage device 30 in advance is calculated based on the calculated value. And the optimum cleaning bias is determined in step S10.

  When the optimum cleaning bias is determined in this way, the control device 13 instructs the cleaning bias control device 18 to perform cleaning at the time of normal image formation by the cleaning bias in step S11, and the subsequent cleaning is performed by this cleaning bias. To be done. Since toner cleaned with a non-optimal cleaning bias remains on the intermediate transfer belt 2, image formation, toner density correction, and the like are performed after the intermediate transfer belt 2 is cleaned with the determined cleaning bias.

  By cleaning the intermediate transfer belt 2 in this way, even if the intermediate transfer belt 2 is deteriorated and its surface state is changed, the image carrier can be used even if the temperature and humidity in the installation environment of the image forming apparatus is changed. Since the background of the intermediate transfer belt 2 is measured, the residual toner density can be accurately grasped based on the measurement result, and even if the environmental state or the surface state of the intermediate transfer belt changes, it is ensured. It is possible to provide a cleaning method in an image forming apparatus capable of cleaning residual toner.

  As described above, the present invention can be implemented not only in the image forming apparatus using the intermediate transfer belt 2 described above but also in the image forming apparatus using the intermediate transfer drum. The present invention can also be applied to a case where not only the intermediate transfer drum but also the residual toner remaining on the recording medium conveying belt for conveying the recording medium and the image carrier such as the photosensitive drum and the photosensitive belt are cleaned. That is, the intermediate transfer drum is exactly the same because the belt is simply replaced with the drum. In the case of the image forming apparatus using the recording medium conveyance belt, the residual toner on the recording medium conveyance belt is biased. A cleaning device that cleans by applying a voltage and a toner concentration measuring device that detects the toner density on the recording medium conveyance belt are provided, and the patch is transferred to the recording medium conveyance belt, and the density is measured by the density sensor. Thus, the present invention can be applied in exactly the same manner.

When the image bearing member is a photosensitive member such as a photosensitive drum or a photosensitive belt, the cleaning device 24 and the density sensor 28 described above include cleaning devices 6 ₁ , 6 ₂ , 6 ₃ , and a cleaning device for residual toner on the photosensitive member. 6 ₄ with using the concentration sensor for toner concentration measurement on the photosensitive member is provided, may be determined similarly cleaning bias was measured patch density and the residual toner density on direct photoreceptor, in which case, The cleaning bias is determined according to the flowchart as shown in FIG. In the case of this flowchart, the density sensor 28 is provided opposite to the photosensitive member, and therefore, in the following description, the description is omitted.

  Further, as in the case of the flow of FIG. 3, the control device starts with the steps of FIG. 4 at a predetermined time during non-image formation, such as when the image forming apparatus is turned on or when returning from the sleep mode for energy saving. In S22, the density sensor measures the state when there is no toner on the photoconductor as the background and stores it in the background data storage device.

  In the next step S23, the control device instructs the exposure control device to form, for example, a solid (100%) toner patch for density measurement on the photoconductor, and the exposure control device performs exposure according to the instruction. A latent image is formed on the photoreceptor. The latent image is developed by a developing device to become a patch toner image.

Then, the control device instructs the sensor driving circuit, reads the density of each patch in step S24, subtracts the background data from the patch density, normalizes it, and checks whether the patch density is higher than the standard value in step S25. If it is below the standard value, the process returns to step 23 again, and the development bias is optimized so that the density of the patch image is equal to or higher than the standard value, and a patch image is formed. Subsequently, in step S26, the control device instructs the transfer bias power source to instruct the transfer roller to be at the ground potential (0 V) so as not to change the toner charge in the patch, and cleans the patch toner image with the cleaning devices 6 ₁ , 6. ₂ , 6 ₃ , and 6 ₄ .

  Further, the control device instructs the cleaning bias control device in the next step S27 to perform cleaning while changing the cleaning bias to, for example, 500, 550, 600,... 1000 (V). This cleaning is preferably performed while changing the formed patch once. Otherwise, the toner cleaned with a cleaning bias that is not suitable for cleaning will remain on the photoreceptor, which may hinder the determination of the optimum cleaning bias.

  When cleaning is performed in this way, the control device instructs the sensor drive circuit in the next step S28 to measure the density of the toner remaining on the photosensitive member, and the background value stored in the background data storage device first. The data is sent to the arithmetic unit together with the data, and the background data is subtracted from the residual toner density and normalized. Then, an actual cleaning situation is calculated by comparing the obtained values, and based on the calculated value, a cleaning bias corresponding to the residual toner density on the photoconductor previously stored in the cleaning bias storage device is read out, In step S29, the optimum cleaning bias is determined.

  When the optimum cleaning bias is thus determined, the control device instructs the cleaning bias control device to perform cleaning at the time of normal image formation by the cleaning bias in step S30, and the subsequent cleaning is performed by this cleaning bias. It becomes like this. Since the toner cleaned with the non-optimal cleaning bias remains on the photoconductor, the image carrier is cleaned with the determined cleaning bias, and then image formation and toner density correction are performed.

  In this way, not only the intermediate transfer belt but also the photosensitive member can be cleaned in the same manner by the optimum cleaning bias, even if the photosensitive member deteriorates and its surface state changes. Since the background of the photoconductor is measured even when the temperature and humidity in the installation environment of the image forming apparatus change, the residual toner density can be accurately grasped based on the measurement result, and the environmental state and the surface of the photoconductor Even when the state changes, it is possible to provide a cleaning method in an image forming apparatus capable of reliably cleaning the remaining toner.

  The operation according to the above-described flow is performed at a predetermined time during non-image formation, such as when the image forming apparatus is turned on or when returning from the sleep mode for energy saving as described above. It may be performed when there is an instruction from the manual button 33 shown in FIG. In this way, it is possible to perform an operation according to this flow at an arbitrary time such as when a defective cleaning is recognized in the formed image or during maintenance, and it is possible to provide a user-friendly cleaning method in the image forming apparatus. In the image forming apparatus, the toner density is adjusted when the power of the image forming apparatus is turned on or when the image forming apparatus is returned from the sleep mode for energy saving.

  As described above, according to the present invention, the background density in the recording medium conveyance belt or the image carrier is measured by the density measuring means, and then the density measurement patch is applied to the recording medium conveyance belt or the image carrier. This patch is cleaned while changing the cleaning bias, and the remaining toner density is measured to determine the optimum cleaning bias, thereby deteriorating the image carrier and recording medium transport belt and changing its characteristics. In addition, it is possible to provide a cleaning method in the image forming apparatus that can optimize the cleaning bias and reliably clean the residual toner even if the temperature and humidity in the installation environment of the image forming apparatus change.

  Further, after the density measurement patch is formed on the image carrier or on the recording medium conveyance belt, before the density measurement patch is cleaned, the toner density of the density measurement patch is measured by the density measurement unit, It is possible to provide a cleaning method and an image forming apparatus that can confirm whether or not the density measurement patch has been formed normally and can accurately determine the cleaning bias.

  The toner density measuring means for measuring the patch density employs a sensor for controlling the image density in the image forming apparatus, thereby implementing the present invention without using any special additional means or complicated mechanism for cleaning as in the prior art. can do.

  In addition, a storage unit storing the cleaning bias corresponding to the output of the toner density measuring unit is provided, the residual toner density is normalized using the background density, and the cleaning bias stored in the storage unit is read based on the normalized result. By changing the cleaning bias, it is possible to always carry out cleaning while grasping the accurate amount of remaining toner.

  In addition, by providing a manual button for carrying out routines for background density measurement, density measurement patch formation, and residual toner density measurement, cleaning can be performed at any time using the manual button, so that image formation is easy to use. A cleaning method in the apparatus can be provided.

  According to the present invention, no special additional means is required. Even if the characteristics of the image carrier and the recording medium conveyance belt are deteriorated and the characteristics thereof are changed, or the temperature and humidity in the installation environment of the image forming apparatus are changed, Therefore, it is possible to provide a cleaning method in an image forming apparatus that can reliably remove residual toner, and to provide an image forming apparatus that does not cause image contamination.

1 is a block diagram schematically showing an example of an image forming apparatus that performs a cleaning method in an image forming apparatus according to the present invention. It is a figure which shows an example of the layer structure outline of an intermediate transfer body. FIG. 3 is a flowchart of a first embodiment of a cleaning method in the image forming apparatus according to the present invention. It is a flowchart of 2nd Example of the cleaning method in the image forming apparatus which becomes this invention. FIG. 3 is a configuration diagram of a toner concentration measuring device used for a cleaning method in the image forming apparatus of the present invention. It is a graph for demonstrating the cleaning condition by the cleaning bias voltage applied to a cleaning brush etc. FIG.

Explanation of symbols

1 Photoconductor (image carrier)
DESCRIPTION OF SYMBOLS 2 Intermediate transfer belt 3 Charging device 4 Exposure by exposure device 5 Developing device 6 Cleaning device 7 Static eliminator 8 Primary transfer roller 10 Reinforcing resin layer 11 Elastic substrate 12 Fluorine resin-containing surface layer 13 Control device 14 Exposure control device 15 Image data 16 Transfer bias power supply 17 Transfer bias control device 18 Cleaning bias control device 19 Sensor drive circuit 20 Arithmetic devices 21, 22 Drive roller and driven roller 23 Backup roller 24 Cleaning device 25 Secondary transfer roller 26 Fixing device 27 Recording medium 28 Density sensor 30 Cleaning Bias storage device 31 Background data storage device 33 Manual button

Claims (8)

A cleaning method in an image forming apparatus in which a toner image formed on an image carrier by an electrophotographic process is transferred, and then toner remaining on the image carrier is cleaned by a cleaning unit to which a bias voltage is applied,
It has a density measuring means for measuring the toner density of the toner image formed on the image carrier, and the background density when the toner image is not formed on the image carrier is measured by the toner density measuring means. A first step of forming a density measurement patch on the image carrier and cleaning while changing a bias voltage applied to the cleaning means; and cleaning in the second step. And a third step of measuring the toner density in the patch on the image carrier by the density measuring means, and the cleaning is performed based on the results measured in the first step, the second step, and the third step. Determining a bias voltage to be applied to the cleaning device, and applying the determined cleaning bias voltage to the cleaning device to perform cleaning. Cleaning method in an image forming apparatus according to claim Ukoto. Image formation in which a toner image formed on an image carrier by an electrophotographic process is transferred to a recording medium conveyed by a recording medium conveyance belt, and the toner attached to the recording medium conveyance belt is cleaned by a cleaning unit to which a bias voltage is applied. A cleaning method in an apparatus,
A density measuring unit that measures a toner density of a toner image transferred to the recording medium conveyance belt; and a density measurement unit that measures a background density when no toner is transferred onto the recording medium conveyance belt. A second step of forming a density measurement patch on the image carrier, transferring the patch to the recording medium conveyance belt, and cleaning while changing a bias voltage applied to the cleaning unit; And a third step of measuring the residual toner density in the patch on the recording medium conveying belt cleaned in the step 2 by the density measuring means, the first step, the second step, and the third step, The bias voltage to be applied to the cleaning means is determined based on the result measured in step (b), and the determined cleaning via is determined. Cleaning method in an image forming apparatus and performing cleaning by applying a voltage to said cleaning means.   After the density measurement patch is formed on the image carrier or the recording medium conveyance belt, the toner density of the density measurement patch is measured by the density measurement unit before the density measurement patch is cleaned. A cleaning method in the image forming apparatus according to claim 1.   The cleaning method for an image forming apparatus according to claim 1, wherein the toner density measurement manual throwing is an image density control sensor in the image forming apparatus.   And storing means for storing the cleaning bias corresponding to the toner density measuring means output in the third step, normalizing the measurement result in the third step with the measurement result in the first step, and normalizing the result. 3. The cleaning method for an image forming apparatus according to claim 1, wherein a cleaning bias stored in the storage unit is read out according to a result, and the cleaning bias is changed.   A manual button for performing the first to third steps is provided in the image forming apparatus, and the bias voltage of the cleaning unit is determined by performing the first to third steps at an arbitrary time by the manual button. A cleaning method in an image forming apparatus according to claim 1 or 2. In an image forming apparatus for transferring a toner image formed on an image carrier by an electrophotographic process and cleaning the toner remaining on the image carrier by a cleaning unit to which a bias voltage is applied.
It has a density measuring means for measuring the toner density of the toner image formed on the image carrier, and the background density when the toner image is not formed on the image carrier is measured by the toner density measuring means. A first step of forming a density measurement patch on the image carrier and cleaning while changing a bias voltage applied to the cleaning means; and cleaning in the second step. And a third step of measuring the toner density in the patch on the image carrier by the density measuring means, and the cleaning is performed based on the results measured in the first step, the second step, and the third step. Determining a bias voltage to be applied to the cleaning device, and applying the determined cleaning bias voltage to the cleaning device to perform cleaning. An image forming apparatus comprising Ukoto. Image formation in which a toner image formed on an image carrier by an electrophotographic process is transferred to a recording medium conveyed by a recording medium conveyance belt, and the toner attached to the recording medium conveyance belt is cleaned by a cleaning unit to which a bias voltage is applied. In the device
A density measuring unit that measures a toner density of a toner image transferred to the recording medium conveyance belt; and a density measurement unit that measures a background density when no toner is transferred onto the recording medium conveyance belt. A second step of forming a density measurement patch on the image carrier, transferring the patch to the recording medium conveyance belt, and cleaning while changing a bias voltage applied to the cleaning unit; And a third step of measuring the residual toner density in the patch on the recording medium conveying belt cleaned in the step 2 by the density measuring means, the first step, the second step, and the third step, The bias voltage to be applied to the cleaning means is determined based on the result measured in step (b), and the determined cleaning via is determined. Image forming apparatus and performing cleaning by applying a voltage to said cleaning means.

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