JP3803055B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine. Transfer conveyor belt A cleaning member that moves on the surface in a state of being opposed to the toner, adheres the toner adhering to the toner adhering member to the surface, and removes the toner adhering to the surface of the cleaning member in contact with the cleaning member surface The present invention relates to an image forming apparatus provided with a cleaning unit.
[0002]
[Prior art]
Conventionally, as a means for cleaning residual toner adhering to an image carrier (toner adhering member) such as a photoconductor drum, generally, a cleaning blade is brought into contact with a counter direction with respect to the surface movement direction of the image carrier, What removes the residual toner on the surface of the image carrier is used. In such a cleaning means, the cleaning blade may be bent (hereinafter referred to as “blade bending”) due to frictional sliding of the cleaning blade with the surface of the image carrier. For this reason, various countermeasures have been proposed in the past for preventing blade curling. For example, in Japanese Patent Application Laid-Open No. 2001-42724, the toner removed by the cleaning blade is continuously deposited on the edge portion of the cleaning blade, and the friction between the cleaning blade and the image carrier surface is reduced by the toner. An image forming apparatus that prevents blade curling has been proposed. For example, Japanese Patent Application Laid-Open No. 10-177330 proposes an image forming apparatus that supplies a lubricant to the image carrier surface in order to reduce friction between the cleaning blade and the image carrier surface. In these publications, the cleaning of the photosensitive drum is described, but the cleaning of the transfer belt and the like can be similarly used.
[0003]
However, when the toner on the image carrier is scraped directly by the cleaning blade in this way, the edge portion of the cleaning blade is pressed against the surface of the image carrier with a relatively high pressure. Large amount of wear. Therefore, there has been a problem that the life of the cleaning blade and the image carrier to be cleaned becomes relatively short.
As a method for solving such a problem, a cleaning roller such as a metal roller is opposed to the image carrier, and a bias is applied to the cleaning roller to remove toner on the image carrier by electrostatic force or the like. There is. In this method, in order to remove the toner adhering to the surface of the cleaning roller, a structure in which a removing blade is brought into contact with the roller surface is often employed. In such a configuration, since the friction between the cleaning roller and the image carrier is small, the life of the image carrier to be cleaned can be extended as compared with the case of using a cleaning blade. In addition, since the amount of toner that can be collected by the cleaning roller from the image carrier while passing through the opposite area between the cleaning roller and the image carrier only once is smaller than when the cleaning blade is used, the cleaning roller. Even if the contact pressure between the surface and the removal blade is set smaller than the contact pressure between the cleaning blade and the image carrier, the toner can be sufficiently removed from the surface of the cleaning roller. Therefore, the life of the removal blade is longer than that of the cleaning blade.
[0004]
[Problems to be solved by the invention]
However, when a cleaning roller provided with a removal blade is used, the removal blade is twisted in the same manner as the cleaning blade described above. In addition, there is a problem that the blade curl of the removal blade that contacts the surface of the cleaning roller is more likely to occur than the cleaning blade that contacts the surface of the image carrier. The reason will be described below.
[0005]
In general, even during a normal image forming operation, the toner remaining on the image carrier without being charged normally or the transfer residual toner adheres to the surface of the image carrier slightly. The toner adhering in this way is transported to the opposing portion of the cleaning blade and the cleaning roller as the surface of the image carrier moves, and is removed from the surface of the image carrier. Therefore, a certain amount of toner is supplied to the cleaning blade and the cleaning roller during the image forming operation. Here, as a result of an experiment by the present inventor, as the amount of toner passing through the contact portion on the image carrier on which the blade comes into contact increases and the amount of toner input to the edge portion of the blade increases, It has been confirmed that the time until this occurs becomes longer.
[0006]
When the cleaning blade is used, almost all the toner adhering to the image carrier by the image forming operation is collected by the cleaning blade when passing through the contact portion on the image carrier, so that the edge portion The amount of toner that is input is large, and the toner that accumulates at the edge of the cleaning blade increases as image formation is performed. As a result, when a cleaning blade is used, it is considered that blade deflection during image forming operations or other than image forming operations is relatively unlikely to occur. On the other hand, when a cleaning roller having a removal blade is used, the toner adhering to the image carrier by the image forming operation is input to the edge portion of the removal blade through the cleaning roller. The amount of input toner is smaller than that of the cleaning blade. For this reason, blade curling is more likely to occur during an image forming operation or at a time other than the image forming operation, compared to the case where a cleaning blade is used.
[0007]
The above-mentioned problem is not limited to the case where the toner on the image carrier such as the photosensitive drum or the intermediate transfer member is removed, but the toner adhering member such as a paper conveying belt to which the toner can adhere during the image forming operation period. The same applies when cleaning is performed.
[0008]
The present invention has been made in view of the above problems, and its object is to Transfer conveyor belt And an image forming apparatus capable of extending the life of the blade-like member used for the cleaning means and suppressing the blade-like member from curling.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 carries and transports a recording material toward a transfer portion facing the image carrier. Transfer conveyor belt And the Transfer conveyor belt The surface moves while facing the Transfer conveyor belt A cleaning member that removes the toner adhering to the surface by removing the toner adhering to the surface, and a removing blade that removes the toner adhering to the surface of the cleaning member in contact with the surface of the cleaning member; A fixing unit for fixing the toner transferred from the image carrier onto the recording material to the recording material; In an image forming apparatus comprising: When more toner than the amount of toner that can adhere to the transfer / conveying belt during image forming operation adheres to the transfer / conveying belt, the toner on the transfer / conveying belt is removed by rotating the transfer / conveying belt a plurality of times. It is configured to be removed by the cleaning means, and a period immediately after turning on the power or warming up of the fixing unit During the period, a toner applying unit that applies toner to the contact portion of the surface of the cleaning member that contacts the removal blade over the contact width of the removal blade in a direction orthogonal to the surface movement direction of the cleaning member. It is characterized by.
In this image forming apparatus, Transfer conveyor belt The surface moves while facing the Transfer conveyor belt A cleaning unit has a cleaning member that adheres and removes toner adhering to the surface and a removal blade that abuts on the surface of the cleaning member and removes toner adhering to the surface of the cleaning member. . This Thus, in the image forming apparatus according to the present invention, normally, toner is not supplied to the contact portion. Warm-up period immediately after power-on or the above fixing unit During the period, the toner is applied by the toner applying means to the contact portion where the removal blade contacts the cleaning member surface. Therefore, depending on the toner Concerned Friction between the removal blade and the surface of the cleaning member during the period can be reduced, and blade removal of the removal blade can be suppressed. Further, when toner is insufficient at a part of the contact portion of the removal blade, particularly at both end portions of the contact portion, the blade may be bent at that portion. In the image forming apparatus according to the present invention, the surface of the cleaning member Since the toner is applied over the contact width of the removal blade in the direction orthogonal to the moving direction, blade curling that occurs at a part of the contact portion of the removal blade can also be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an electrophotographic color laser printer (hereinafter referred to as “laser printer”) as an image forming apparatus will be described.
FIG. 2 is a schematic configuration diagram of the laser printer according to the present embodiment. This laser printer has four sets of image forming means 1M, 1C, 1Y, 1K (hereinafter referred to as each of the image forming means for forming images of each color of magenta (M), cyan (C), yellow (Y), and black (K). The subscripts M, C, Y, and K indicate the members for magenta, cyan, yellow, and black, respectively) in the moving direction of the transfer paper as the transfer material (the direction of arrow A in the figure). Arranged in order from the upstream side. Each of the image forming units 1M, 1C, 1Y, and 1K includes a photoconductor unit having photoconductor drums 11M, 11C, 11Y, and 11K as image carriers, and a developing unit. The image forming units 1M, 1C, 1Y, and 1K are arranged so that the rotation axes of the photoconductor drums in the photoconductor units are parallel to each other and arranged at a predetermined pitch in the transfer paper moving direction. Is set.
[0011]
In addition to the image forming means 1M, 1C, 1Y, and 1K, the laser printer supplies transfer paper toward the optical writing unit 2, the paper feed cassettes 3 and 4, and a transfer portion that faces each photosensitive drum 11. The image forming apparatus includes a transfer unit 6 having a transfer belt 60 composed of a transfer conveyance belt for conveyance, a registration roller 5 composed of a pair of rollers for supplying transfer paper to the transfer belt 60, a belt fixing type fixing unit 7, a paper discharge tray 8, and the like. ing. The laser printer also includes a manual feed tray, a toner supply container, a waste toner bottle, a duplex / reversing unit, a power supply unit, etc. (not shown).
[0012]
The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photosensitive drums 11M, 11C, 11Y, and 11K while scanning the laser beam based on image data. To do.
[0013]
Also, the alternate long and short dash line in FIG. 2 indicates the transfer path of the transfer paper. The transfer paper fed from the paper feed cassettes 3 and 4 is conveyed by a conveyance roller while being guided by a conveyance guide (not shown), and is sent to a temporary stop position where the registration roller 5 is provided. The transfer paper is supplied to the transfer belt 60 by the registration roller 5 at a predetermined timing, and is conveyed so as to pass through each transfer portion facing each photoconductor drum 11. As a result, the toner images on the photosensitive drums 11 formed by the image forming units 1M, 1C, 1Y, and 1K are sequentially superimposed and transferred onto the transfer paper, and a color image is formed on the transfer paper. The transfer paper on which the color image is formed is discharged onto the paper discharge tray 8 after the toner image is fixed by the fixing unit 7.
[0014]
FIG. 3 is an enlarged view showing a schematic configuration of the yellow image forming means 1Y among the image forming means 1M, 1C, 1Y, 1K. Since the other image forming means 1M, 1C, and 1K have the same configuration, their descriptions are omitted.
In FIG. 3, the image forming means 1Y includes the photoconductor unit 10Y and the developing unit 20Y as described above. In addition to the photosensitive drum 11Y, the photosensitive unit 10Y includes a cleaning blade 13Y as a swingable photosensitive member cleaning means for cleaning the surface of the photosensitive drum, and a non-contact type charging that uniformly charges the surface of the photosensitive drum. A roller 15Y and the like are provided. In addition, a lubricant application / static brush roller 12Y having a function of applying a lubricant to the surface of the photosensitive drum and discharging the surface of the photosensitive drum is also provided. The lubricant application and static elimination brush roller 12Y has a brush portion made of a conductive fiber, and a power supply for static elimination (not shown) for applying a static elimination bias is connected to the cored bar portion.
[0015]
In the photoreceptor unit 10Y having the above configuration, the surface of the photoreceptor drum 11Y is uniformly charged by the charging roller 15Y to which a voltage is applied. When the surface of the photosensitive drum 11Y is irradiated with the laser beam modulated and deflected by the optical writing unit 2 while being scanned, an electrostatic latent image is formed on the surface of the photosensitive drum 11Y. The electrostatic latent image on the photosensitive drum 11Y is developed by a developing unit 20Y described later to become a yellow toner image. In the transfer portion Pt through which the transfer paper 100 on the transfer belt 60 passes, the toner image on the photosensitive drum 11Y is transferred to the transfer paper 100. The surface of the photosensitive drum 11Y after the toner image is transferred is coated with a predetermined amount of lubricant by the lubricant application / static brush brush 12Y and discharged, and then cleaned by the cleaning blade 13Y. Prepared for formation of an electrostatic latent image.
[0016]
The developing unit 20Y uses a two-component developer containing a magnetic carrier and negatively charged toner as a developer for developing the electrostatic latent image. The developing unit 20Y includes a developing roller 22Y as a developer carrying member disposed so as to be partially exposed from the opening on the photosensitive drum side of the developing case 21Y, conveying screws 23Y and 24Y, a developing doctor 25Y, A toner concentration sensor (T sensor) 26Y, a powder pump 27Y, and the like are provided.
[0017]
In FIG. 3, the developer accommodated in the developing case 21Y is frictionally charged by being agitated and conveyed by the conveying screws 23Y and 24Y. A part of the developer is carried on the surface of the developing roller 22Y, the layer thickness is regulated by the developing doctor 25Y, and then conveyed to the developing position facing the photosensitive drum 11Y. At the developing position, the electrostatic latent image on the photosensitive drum 11Y is developed by the charged toner in the developer on the developing roller 22Y. The toner density of the developer in the developing case 21Y is detected by the toner density sensor 26Y, and the toner is replenished by the powder pump 27Y as necessary.
[0018]
FIG. 4 is a schematic configuration diagram of the transfer unit 6. As a material of the transfer belt 60 of the transfer unit 6, for example, PVDF (polyvinylidene fluoride) can be used. The transfer belt 60 is rotatably stretched by four grounded support rollers 61, 62, 63, and 64. The exit roller 62 on the downstream side in the transfer sheet moving direction is a drive roller that frictionally drives the transfer belt 60 and is connected to a drive source (not shown). When the transfer belt 60 is rotated in the direction of the arrow by the exit roller 62, the transfer paper 100 is carried and conveyed toward the transfer portions facing the photosensitive drums 11M, 11C, 11Y, and 11K of the respective image forming means. .
[0019]
Further, transfer bias applying members 67M, 67C, 67Y, and 67K are provided as transfer electric field forming means for forming a transfer electric field in each transfer portion. These transfer bias applying members 67M, 67C, 67Y, and 67K are opposed to the respective photosensitive drums 11M, 11C, 11Y, and 11K so as to be in contact with the back surface of the transfer belt 60, and for transferring the toner images of the respective colors. A transfer nip is formed. The transfer bias applying members 67M, 67C, 67Y, and 67K used in the present embodiment are fixed Mylar brushes, and the transfer bias power supplies 9M, 9C, 9Y, and 9K are charged with the charging polarity of the toner as a transfer bias. Is configured so that a positive voltage of reverse polarity is applied. A transfer charge is applied to the transfer belt 60 by the transfer bias applied through the transfer bias applying members 67M, 67C, 67Y, and 67K, and the surface of the photosensitive drums 11M, 11C, 11Y, and 11K and the transfer are transferred at each transfer portion. A transfer electric field having a predetermined strength is formed between the belt 60 and the belt 60.
[0020]
The transfer unit 6 is provided with backup rollers 68M, 68C, 68Y, and 68K that press the transfer belt 60 against the photosensitive drums 11M, 11C, 11Y, and 11K. The transfer belt 60 is wound around a part of the circumferential surface of the photosensitive drum 11Y on the upstream side. As a result, the contact pressure between the transfer paper 100 and each photosensitive drum in the transfer nip is increased, and the transfer efficiency of each toner image in each transfer portion is increased.
[0021]
Further, an electrostatic adsorption roller 65 is provided at a portion facing the support roller 61 of the transfer unit 6 as a transfer material adsorption electrode member so as to be in contact with and opposed to the transfer belt 60. The electrostatic attraction roller 65 has a conductive foam elastic body layer formed on a cored bar. Examples of the material of the elastic layer include a specific resistivity of 10 ^Five An Ωcm chloroprene rubber can be used. A voltage is selectively applied to the electrostatic attracting roller 65 from a power supply 65a for transferring paper and a power supply 65b for reverse polarity as bias applying means. The power supply 65a for attracting the transfer paper is a constant current control type power supply, and applies a positive polarity charge opposite to the normal polarity of the toner to the transfer paper. In the present embodiment, the current flowing through the support roller 61 is controlled to be, for example, plus 15 μA. The transfer paper that has passed between the electrostatic suction 65 and the support roller 61 in a state where power is supplied from the power supply 65 a for sucking the transfer paper is electrostatically attracted onto the transfer belt 60. The reverse polarity power supply 65b is a constant voltage control type power supply, which increases the charge of negatively charged toner, which is the normal polarity on the transfer belt 60, or is positively charged reverse polarity toner. Or the negatively charged toner adhering to the surface of the electrostatic attraction roller 65 is transferred to the surface of the transfer belt 60 to clean the electrostatic attraction roller 65. In the present embodiment, for example, a constant voltage of minus 2 kV is applied to the suction roller 65. Note that switching of the voltage applied to the electrostatic attraction roller 65 is performed by a main body control unit (not shown).
[0022]
Further, in the transfer unit 6, as a bias cleaning type cleaning unit that removes toner adhering to the surface of the transfer belt 60 at a portion stretched by the two support rollers 63 and 64 of the transfer belt 60. A bias cleaner 70 is provided. The bias cleaner 70 is configured to move the conductive cleaning roller 71 facing the surface of the transfer belt 60 and the negatively charged toner between the cleaning roller 71 and the transfer belt 60 toward the cleaning roller 71. A cleaning bias power source 75 is provided as a cleaning bias applying means for applying a bias to the cleaning roller 71 to form a cleaning electric field. A removal blade 72 is also provided for removing toner adhering to the cleaning roller 71 from the roller surface. The removal blade 72 is arranged to contact the surface of the cleaning roller 71 with a contact width slightly wider than the image area width in the axial direction of the cleaning roller 71. A counter roller 73 biased by a spring 74 is provided at a position facing the cleaning roller 71 with the transfer belt 60 interposed therebetween.
[0023]
Next, the cleaning operation of the transfer belt 60 in the laser printer, which is a characteristic part of the present invention, will be described.
In the laser printer according to the present embodiment, a cleaning mode in which the toner attached on the transfer belt 60 is removed by the bias cleaner 70, and the toner is forcibly input to the removal blade 72 provided in the bias cleaner 70. A toner input mode for preventing drowning.
[0024]
In the cleaning mode, a positive voltage with constant current control of, for example, 15 μA is applied to the cleaning roller 71 as a cleaning bias from the cleaning bias power supply 75. As a result, a cleaning electric field for moving the negatively charged toner toward the cleaning roller 71 is formed between the surface of the transfer belt 60 and the cleaning roller 71. The negatively charged toner adhering to the surface of the transfer belt 60 during the image forming operation receives an electrostatic force from the cleaning electric field and transfers to the cleaning roller 71, and the surface of the transfer belt 60 is cleaned. The toner transferred to the cleaning roller 71 in this way is scraped off by the removal blade 72 that contacts the surface of the cleaning roller 71 and is removed from the surface of the cleaning roller 71.
[0025]
In the case where the toner adhered on the transfer belt 60 is transferred to the cleaning roller 71 for cleaning, for example, a paper jam or the like may occur, and the toner image may be transferred onto the transfer belt 60. When this happens, it is very difficult to remove all of the toner on the transfer belt 60 by removing the toner by the cleaning roller 71 once. Therefore, when a large amount of toner adheres on the transfer belt 60 in this way, the transfer belt 60 is rotated an appropriate number of times to remove all the toner. The same applies to the case where a pattern created for process control or a pattern created for color matching is created on the transfer belt 60. However, the toner adhering to the transfer belt 60 by a normal image forming operation can be sufficiently cleaned by removing the toner by the cleaning roller 71 once.
[0026]
Here, since the toner on the transfer belt 60 passes through the cleaning region where the cleaning roller 71 and the transfer belt 60 face each other, the amount of toner input to the edge portion of the removal blade 72 that contacts the cleaning roller 71 is the largest. This is when the toner image is transferred onto the transfer belt 60 due to a paper jam or the like. However, the toner adhering in a large amount on the transfer belt 60 in this way can be removed only once through the cleaning area when the cleaning blade is used, but the cleaning roller 71 allows the cleaning area to pass through a plurality of times. Will be removed. Therefore, the amount of toner that must be removed by the removal blade 72 is much less than in the case of a cleaning blade that removes toner directly from the transfer belt 60. As a result, when the cleaning roller is used, the contact pressure of the removal blade 72 can be set lower than that in the case of the cleaning blade, and this can suppress wear of the blade edge, so that its life is also set longer. Can do.
[0027]
However, when the image forming operation is continuously performed, the state where almost no toner is input to the edge portion of the removal blade 72 continues. For this reason, when continuous image forming operations continue, the toner staying at the edge portion of the blade gradually disappears, and eventually the blade is bent. Therefore, in this embodiment, in order to suppress such blade curling, a toner input mode for forcibly inputting toner to the removal blade 72 is executed during the non-image forming operation period.
[0028]
In this toner input mode, one of the four sets of image forming means 1M, 1C, 1Y, 1K is used as the toner applying means. In this embodiment, an image forming unit that performs normal image formation is used as the toner applying unit. However, any toner can be applied over the contact width of the removal blade 72 in the axial direction of the cleaning roller 71. A toner application device dedicated to the toner input mode may be provided. In this toner input mode, any color image forming means may be used. In this embodiment, among the four sets of image forming means 1M, 1C, 1Y, 1K, a yellow toner image is generated. The image forming means 1Y is used. This is because the toner formed on the transfer belt 60 in the toner input mode cannot be completely removed by the cleaning roller 71, and the residual toner does not stand out even if it adheres to the back surface of the transfer paper for the next image forming operation. It is.
[0029]
Further, in order to stably prevent blade curling, the toner input mode is periodically executed, for example, after a predetermined time has elapsed after a predetermined number of image forming operations have been performed. desirable. The timing of the toner input mode may be any time as long as it is a non-image forming operation as long as it does not interfere with the normal image forming operation. However, since it takes a certain amount of time to complete the toner input mode, it is relatively long. It is desirable to set the period in which the time image forming operation is not performed. Specifically, the toner input mode is executed in a period immediately after the power is turned on, a warm-up period of each part of the apparatus such as the fixing unit 7, a period for process control, or the like, or continuously before or after these periods. Like that. Note that process control generally means control for always setting image forming conditions appropriately in an image forming apparatus, and specifically, a detection result of a toner adhesion amount and a surface potential of the photosensitive drum 11. In contrast to the control for setting the light emission amount of the optical writing unit 2, the charging potential of the photosensitive drum 11, the developing bias, the toner replenishment amount, etc., in this specification, the photosensitive drums 11M, 11C, 11Y, Control for aligning (color matching) each color toner image transferred from 11K to the transfer paper is also included.
[0030]
FIG. 1 is a timing chart when the toner input mode is executed during a period for process control or color matching. FIG. 5 shows a pattern image or color matching image on the transfer belt 60 and a toner input image. It is explanatory drawing which shows these positional relationships. In the period for process control or color matching, as shown in FIG. 1A, first, a pattern image or color matching image is created on the transfer belt 60 using each of the image forming means 1M, 1C, 1Y, 1K. Thereafter, pattern density detection or position detection is performed, and an optimum development bias and transfer bias or image formation timing is set. After performing pattern density detection and position detection in the period for process control or color matching, the pattern image or color matching image created on the transfer belt 60 is cleaned as shown in FIG. It is removed by the roller 71. As a result, toner is input to the removal blade 72. Normally, however, the pattern image or the color matching image is perpendicular to the surface movement direction of the transfer belt 60 in order to minimize the toner consumption. It is not created to fill the entire image area width. For this reason, toner is input to a part of the contact width of the removal blade 72 by process control or color matching, but the blade curl will eventually occur in a portion where no toner is input.
[0031]
Therefore, in the present embodiment, as shown in FIG. 1B, immediately after the pattern image or color matching image is created on the transfer belt 60 during the process control or color matching period, the image forming means 1Y. Thus, a toner input image is created. The toner input image created on the transfer belt 60 in this manner is removed from the transfer belt 60 together with the pattern image or the color matching image by the toner removal by the cleaning roller 71 during the period for process control or color matching. Is done. If the toner input mode is executed at such timing, it is not necessary to provide a period for creating a toner input image on the transfer belt 60 or cleaning it for only the toner input mode, which is efficient. It is possible to suppress blade curling.
[0032]
FIG. 6 shows the image area on which an image is formed by a normal image forming operation, the contact width of the removal blade, and the width of the toner input image on the transfer belt 60 in order to explain the width of the toner input image. It is explanatory drawing shown virtually. In the present embodiment, as shown in the drawing, a toner input image having a width slightly wider than the entire image area width is formed. The width of the toner input image is equal to or larger than the contact width of the removal blade 72 that contacts the cleaning roller 71. As a result, the toner constituting the toner input image is removed by the cleaning roller 71, and finally input over the entire contact width of the removal blade 72.
[0033]
In this embodiment, the case where the toner input image is created immediately after the pattern image or the color matching image is created on the transfer belt 60 has been described. However, the image area in the direction orthogonal to the surface movement direction of the transfer belt 60 is described. If a pattern image or color matching image over the entire width is created, the pattern image or color matching image can also be used as a toner input image.
[0034]
In addition, among the toners constituting the toner input image, there are toners that are positively charged due to polarity reversal caused by a transfer bias or the like when transferred from the photosensitive drum 11Y onto the transfer belt 60. Sometimes. In this case, the positively charged toner whose polarity has been reversed cannot be transferred to the cleaning roller 71 side by the cleaning electric field applied by the biased cleaning roller 71. Therefore, the toner on the transfer belt 60 that has undergone the polarity reversal remains on the transfer belt 60 without being cleaned by the cleaning roller 71. Therefore, in the present embodiment, after the toner input image is created on the transfer belt 60 by the image forming means 1Y, the toner constituting the toner input image is charged so as to have a negative polarity with normal polarity. A charge imparting means for imparting is provided.
[0035]
The charge applying unit is disposed on the downstream side in the surface movement direction of the transfer belt 60 so as to face the transfer belt 60 rather than the toner applying unit that creates the toner input image on the transfer belt 60. In the present embodiment, the image forming unit 1K positioned on the downstream side of the surface movement direction of the transfer belt 60 with respect to the image forming unit 1Y as the toner applying unit, and the transfer bias applying member 67K of the transfer unit 6 corresponding to the image forming unit 1K Charge providing means is configured. That is, after the toner input image is created on the transfer belt 60 by the image forming means 1Y, the reverse bias is applied to the transfer bias applying member 67K when the toner input image passes through the transfer portion of the image forming means 1K. A bias is applied by the power source 65b. As a result, all of the toner constituting the toner input image that has passed through the transfer portion of the image forming means 1K is in a negatively charged state and can be transferred to the cleaning roller 71, thereby preventing remaining cleaning. . In addition, you may provide the charge provision means which provides the electric charge for aligning the polarity of the toner which comprises a toner input image separately separately.
[0036]
In addition, as a result of experiments, the present inventor has confirmed that blade cleaning does not occur even when the toner input mode is not executed under the conditions of low temperature and low humidity when the cleaning roller 71 including the removal blade 72 is used. did. Therefore, the laser printer of this embodiment is provided with a temperature / humidity sensor as temperature / humidity detection means for detecting temperature and humidity. Then, as a result of detection by the temperature / humidity sensor, when it is determined that the blade is not twisted, that is, in a low temperature and low humidity environment, the toner input mode is not executed. Thereby, useless toner consumption can be suppressed.
[0037]
In the present embodiment, the toner input image created in the toner input mode is formed on the transfer belt 60 after an electrostatic latent image corresponding to the toner input image is formed on the photosensitive drum 11Y. However, it is also possible to adopt a configuration in which toner is deposited on the photosensitive drum by simple bias development without forming an electrostatic latent image, and this is transferred onto the transfer belt 60. In addition, the length of the toner input image in the surface movement direction of the transfer belt 60 is determined to be an appropriate length according to the execution interval of the toner input mode. Specifically, a period until the blade wrinkles of the removal blade 72 is experimentally obtained from the total amount of toner input to the edge portion of the removal blade 72 by a predetermined number of image forming operations, and the execution interval of the toner input mode is determined. At the same time, the length of the toner input image is determined. In this case, the longer the toner input mode execution interval, the longer the toner input image length. The shorter the toner input mode execution interval, the shorter the toner input image length.
[0038]
As described above, according to the present embodiment, the surface moves while facing the transfer belt 60 as a toner adhesion member to which toner can adhere during the image forming operation period, and the toner adhered on the transfer belt 60 adheres to the surface. An image provided with a bias cleaner 70 as a cleaning means having a cleaning roller 71 as a cleaning member to be removed and a removal blade 72 for removing toner adhering to the surface of the cleaning roller 71 in contact with the roller surface. The removal blade 72 on the surface of the roller contacts the laser printer as the forming apparatus over the contact width of the removal blade 72 in the direction (axial direction) orthogonal to the surface movement direction of the cleaning roller 71 during the non-image forming operation period. Image forming hand as toner applying means for applying toner to the contact portion Is provided with the 1Y and the transfer bias applying members 67Y of the transfer unit 6, without interfering with the normal image forming operation, it is possible to suppress the blade curling over contact the entire width of the removal blade 72.
In addition, toner is applied to the contact portion of the removal blade 72 by attaching toner on the transfer belt 60 and removing the toner attached on the transfer belt 60 by attaching it to the surface of the cleaning roller 71. As the means, an image forming means 1Y is used, and a control unit (not shown) is provided as a process control means for performing process control based on the amount or position of toner attached to the transfer belt 60 by the image forming means 1Y. For example, as described above, the pattern image or color matching image for process control can be used as a toner input image for preventing blade blurring of the removal blade 72, thereby improving time efficiency while suppressing wasteful toner consumption. be able to.
In addition, a control unit (not shown) is provided as process control means for performing process control based on the amount or position of toner deposited on the transfer belt 60 during the non-image forming operation period, as in the above embodiment. If the toner is applied to the contact portion of the removal blade 72 by the image forming unit 1Y while the process control is performed by the control unit, the time efficiency can be improved.
Further, as in the above-described embodiment, the image forming apparatus includes a plurality of image forming units 1M, 1C, 1Y, and 1K as toner image forming units that respectively form a plurality of color toner images on a transfer sheet as an image carrier. If the toner input image is formed by using one of the plurality of image forming units 1M, 1C, 1Y, and 1K as the applying unit, two or more image forming units 1M, 1C, 1Y, and 1K are used. Thus, wasteful toner consumption can be suppressed as compared with the case of forming a toner input image.
In particular, if the image forming unit 1Y that forms a yellow toner image is also used as the toner applying unit, the toner cannot be completely removed by the cleaning roller 71, and an image formed by the next image forming operation or the back surface of the transfer paper Even if the toner adheres to the other color, it is less noticeable than other colors, and the influence of toner remaining without being removed by the cleaning roller 71 can be reduced.
Further, as in the above-described embodiment, the toner is attached on the transfer belt 60, and the toner attached on the transfer belt 60 is attached to the surface of the cleaning roller 71 and removed, so that the contact portion of the removal blade 72 is removed. An image forming unit 1Y is used as a toner applying unit for applying toner to the toner, and an electric field forming unit for forming a cleaning electric field for moving the toner attached on the transfer belt 60 to the cleaning roller 71 side by the image forming unit 1Y. After the toner is attached to the transfer belt 60 by the cleaning roller 71, the counter roller 73, the cleaning bias power source 75, and the image forming means 1Y, the toner is moved to the cleaning roller 71 side by receiving the cleaning electric field. As a charge imparting means for imparting a positive charge (negative charge) to the toner By providing the image biasing member 67K of the image unit 1K and the transfer unit 6, even when the toner charged non-uniformly by the image forming unit 1Y is formed on the transfer belt 60, the cleaning roller 71 can reliably It can be removed from the transfer belt 60. Therefore, a desired amount of toner can be reliably input to the removal blade 72.
Further, as in the above embodiment, a temperature / humidity sensor is provided as a temperature detecting means for detecting temperature and a humidity detecting means for detecting humidity, and as a result of detection by the temperature / humidity sensor, both temperature and humidity are below a predetermined value. The toner input mode is not executed in a certain low temperature and low humidity environment, and the toner input image is not formed by the image forming means 1Y, thereby suppressing wasteful toner consumption in a low temperature and low humidity environment where no blade wrinkles occur. be able to.
[0039]
In the present embodiment, the configuration in which the toner images formed on the photosensitive drums 11M, 11C, 11Y, and 11K are directly formed on the transfer paper has been described. However, for example, on the photosensitive drums 11M, 11C, 11Y, and 11K. The same applies to an image forming apparatus configured to transfer the toner image formed on the intermediate transfer member once onto the intermediate transfer member and then transfer the toner image on the intermediate transfer member onto the transfer paper. In this embodiment, a so-called tandem image forming apparatus using four photosensitive drums 11M, 11C, 11Y, and 11K has been described. However, a monochrome or color image forming apparatus having a single photosensitive drum is also used. It is the same.
In the present embodiment, the case where the present invention is applied to the cleaning unit for the transfer belt 60 has been described. It is also possible.
[0040]
【The invention's effect】
According to the first to seventh aspects of the present invention, the cleaning member that moves on the surface is used instead of the cleaning blade, and the blade is bent over the entire contact width of the removal blade that contacts the surface of the cleaning member without disturbing the normal image forming operation. Because it can be suppressed Transfer conveyor belt In addition, the blade-like member (removal blade) used for the cleaning means can have a long life, and the blade-like member can be prevented from curling.
[Brief description of the drawings]
FIG. 1 is a timing chart when a toner input mode in a laser printer according to an embodiment is executed during a period for process control or color matching.
FIG. 2 is a schematic configuration diagram of the laser printer.
FIG. 3 is an enlarged view showing a schematic configuration of image forming means of the laser printer.
FIG. 4 is a schematic configuration diagram of a transfer unit of the laser printer.
FIG. 5 is an explanatory diagram showing a positional relationship between a pattern image or color matching image on a transfer belt and a toner input image in the laser printer.
FIG. 6 is an explanatory diagram virtually showing an image area on which an image is formed by a normal image forming operation, a contact width of a removal blade, and a width of a toner input image on a transfer belt.
[Explanation of symbols]
1 Image creation means
6 Transfer unit
11 Photosensitive drum
20 Development unit
60 Transfer belt
70 Bias cleaner
71 Cleaning roller
72 Removal blade
75 Cleaning bias power supply

Claims (7)

A transfer conveyance belt for carrying and conveying a recording material toward a transfer portion facing the image carrier;
Move surface while facing the said transfer conveyor belt, those cleaning member for removing by adhering toner adhering to the transfer conveyance belt on the surface, and the toner deposited on the surface of the cleaning member to the cleaning member surface Cleaning means having a removal blade for contact and removal ;
In an image forming apparatus comprising a fixing unit for fixing the toner transferred onto the recording material from above the image carrier to the recording material ,
When more toner than the amount of toner that can adhere to the transfer / conveying belt during image forming operation adheres to the transfer / conveying belt, the toner on the transfer / conveying belt is removed by rotating the transfer / conveying belt a plurality of times. It is configured to be removed by the cleaning means,
The contact of the removal blade on the surface of the cleaning member over the contact width of the removal blade in the direction perpendicular to the surface movement direction of the cleaning member during the period immediately after the power is turned on or during the warm-up period of the fixing unit. An image forming apparatus comprising toner applying means for applying toner to a portion. The image forming apparatus according to claim 1.
The toner applying means, by adhering toner to the transfer conveyance belt, the toner adhering to the transfer conveyance belt by removing by adhering to the cleaning member surface, which imparts the toner to the contact portion And
An image forming apparatus comprising process control means for performing process control based on an adhesion amount or adhesion position of toner adhered on the transfer / conveying belt by the toner applying means. A transfer conveyance belt for carrying and conveying a recording material toward a transfer portion facing the image carrier;
The cleaning member moves on the surface in a state of being opposed to the transfer conveyance belt, and removes the toner adhering to the transfer conveyance belt by adhering to the surface, and the toner adhering to the surface of the cleaning member is applied to the surface of the cleaning member. In an image forming apparatus provided with a cleaning unit having a removal blade for contact and removal ,
When more toner than the amount of toner that can adhere to the transfer / conveying belt during image forming operation adheres to the transfer / conveying belt, the toner on the transfer / conveying belt is removed by rotating the transfer / conveying belt a plurality of times. It is configured to be removed by the cleaning means,
Based on the adhesion amount or deposition position of the toner adhering to the upper Symbol transfer conveyor belt, a process control means for performing process control,
While the process control is performed by the process control means, the toner is applied to the contact portion of the cleaning blade that contacts the removal blade over the contact width of the removal blade in the direction perpendicular to the surface movement direction of the cleaning member. An image forming apparatus comprising: a toner applying unit that applies a toner . The image forming apparatus according to claim 1, 2 or 3.
A plurality of toner image forming means for forming toner images of a plurality of colors on the image carrier,
An image forming apparatus using one of the plurality of toner image forming units and the image carrier as the toner applying unit. The image forming apparatus according to claim 4.
The toner image forming means used as the toner applying means forms a yellow toner image. The image forming apparatus according to claim 1, 2, 3, 4 or 5.
The toner applying means, by adhering toner to the transfer conveyance belt, the toner adhering to the transfer conveyance belt by removing by adhering to the cleaning member surface, which imparts the toner to the contact portion And
An electric field forming means for forming a cleaning electric field for moving the toner attached on the transfer conveyance belt to the cleaning member side by the toner applying means;
After depositing the toner onto the transfer conveyor belt by the toner applying means, an electric charge, such as toner attached to the transfer conveyor belt by said toner applying means to move the cleaning member side by receiving the cleaning electric field An image forming apparatus comprising: a charge applying unit that applies the toner. The image forming apparatus according to claim 1, 2, 3, 4, 5 or 6.
A temperature detecting means for detecting the temperature and a humidity detecting means for detecting the humidity;
An image forming apparatus, wherein when the detection result of the temperature detection means is not more than a predetermined value and the detection result of the humidity detection means is not more than a predetermined value, the toner application by the toner application means is not performed.

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