JP2007047550A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for preventing the damage of an image forming apparatus and accurately performing resist control in the image forming apparatus equipped with an image carrier constituted so that a toner image can be carried on its surface and a cleaning means removing residual toner on the surface of the image carrier while abutting on the image carrier. <P>SOLUTION: When detecting a new transfer unit including an intermediate transfer belt and a cleaner abutting on the intermediate transfer belt, the initializing operation of the transfer unit is performed. When the image forming apparatus is used as a color image forming apparatus, toner accumulation processing (step S204) accumulating prescribed amount of toner at an abutting part between the intermediate transfer belt and the cleaner is performed. The rotation cycle of the intermediate transfer belt is measured while the toner is accumulated (step S205), and resist controlled variable is set based on the result of the measurement. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes an image carrier that is configured to carry a toner image on its surface and moves around in a predetermined direction, and a cleaning unit that contacts the image carrier and removes residual toner on the surface of the image carrier. The present invention relates to an image forming apparatus and an image forming method using the apparatus.

  An image forming apparatus that forms a toner image on an image carrier is configured to execute a control operation (registration control) for properly maintaining the position where the toner image is formed on the image carrier. is there. For example, in the image forming apparatus described in Patent Document 1, it is possible to cope with a slight fluctuation in the rotation speed of the intermediate transfer belt due to the separation and contact operation of the cleaner blade (cleaning unit) with respect to the intermediate transfer belt which is an image carrier. The resist control is performed as follows. That is, in this apparatus, the rotation cycle of the intermediate transfer belt is measured in each state while changing the contact state of the cleaner blade to the intermediate transfer belt. More specifically, (1) a rotation in which the cleaner blade is brought into contact with the intermediate transfer belt in the middle, (2) a turn in which the contact state is maintained, and (3) the cleaner blade is separated from the intermediate transfer belt in the middle. The rotation cycle of the intermediate transfer belt is measured for the four states of the rotation and (4) the rotation in which the separated state is maintained.

  Then, based on the measurement result, the transfer position of the toner image onto the intermediate transfer belt is controlled. That is, when the toner image is transferred onto the intermediate transfer belt, it is determined whether the rotation of the intermediate transfer belt corresponds to the above (1) to (4), and from the measurement result of the corresponding rotation period. The transfer position is shifted by the calculated registration control amount.

JP 2001-235924 A (FIG. 8)

  In the above-described conventional image forming apparatus, immediately after the apparatus is turned on, before the image is formed, the period of the intermediate transfer belt is measured as part of the initialization operation of the apparatus. However, special consideration is required when the intermediate transfer belt is new, such as when the apparatus is new or immediately after the intermediate transfer belt is replaced. The reason is as follows.

  In an actual working state of this type of image forming apparatus, a part of the toner removed from the intermediate transfer belt (image carrier) by the cleaning blade (cleaning means) is accumulated on the contact portion between the two, It is known that it acts as a lubricant between the cleaning means and the image carrier to reduce friction between them. On the other hand, when the apparatus is new, such toner accumulation does not exist. For this reason, when the apparatus is new, if the cycle is measured by rotating the image carrier while the cleaning unit is in contact, the cleaning unit and the image carrier may be damaged by friction. In addition, the period of the image carrier is measured under a state different from the actual operation state of the apparatus, and as a result, the accuracy of resist control may be reduced.

  The present invention has been made in view of the above problems, and an image carrier configured to be able to carry a toner image on its surface, and a cleaning unit that contacts the image carrier and removes residual toner on the surface of the image carrier. In an image forming apparatus including the image forming method and an image forming method using the apparatus, it is an object to provide a technique capable of preventing damage to the apparatus and performing resist control with high accuracy.

  In order to achieve the above object, a first aspect of an image forming apparatus according to the present invention is configured to support a toner image on a surface thereof and to form a toner image, an image carrier that circulates in a predetermined direction. Image forming means to be carried on the surface of the image carrier, cleaning means for removing residual toner from the surface of the image carrier in contact with the image carrier, and image formation on the image carrier by the image forming means Control means for performing registration control for controlling the position, and when the control means determines that the image carrier is new, the image forming means sends a toner image for depositing a predetermined pattern to the image carrier. A toner depositing process in which the toner image is sent to a contact portion between the image carrier and the cleaning unit and toner is deposited on the contact portion, and the image carrier is rotated. The image carrier It performs the processing period for measuring the rotational period measurement in this order, is characterized by performing the registration control based on the measurement result in the period measurement process.

  According to a second aspect of the image forming apparatus of the present invention, in order to achieve the above object, a toner image is formed on the surface of the image forming apparatus so as to be able to carry a toner image. An image forming unit to be carried on the surface of the image carrier, a cleaning unit for coming into contact with the image carrier to remove residual toner on the surface of the image carrier, and an image forming unit on the image carrier. Control means for performing registration control for controlling the image forming position, and the control means executes a new article judgment process for judging whether or not the image carrier is new when the apparatus is turned on. When it is determined that the image carrier is new, the image forming unit forms a toner image for toner deposition having a predetermined pattern on the image carrier, and the toner image is cleaned with the image carrier and the cleaning member. In contact with the means The period measurement is performed in this order by a toner accumulation process for depositing toner on the contact portion and a period measurement process for measuring the rotation period of the image carrier when the image carrier is rotated. The resist control is performed based on a measurement result in the processing.

  The image forming method according to the present invention is configured to be able to carry a toner image on the surface, and is configured to be able to move in a predetermined direction so as to be able to come into contact with and separate from the image carrier. An image forming method using an image forming apparatus provided with a cleaning unit that removes residual toner on the surface of the image carrier in contact with the carrier, wherein the image carrier is a new one in order to achieve the above object. At one time, the image forming unit forms a toner image for toner deposition with a predetermined pattern on the image carrier, and sends the toner image to a contact portion between the image carrier and the cleaning unit. Toner accumulation processing for depositing toner on the contact portion, and period measurement processing for measuring the rotation period of the image carrier when the image carrier is rotated in a state where the cleaning unit is in contact with the image carrier. And in this order Advance, when forming an image based on the measurement result of the cycle measuring processing is characterized in that the resist control for controlling the image forming position to said image bearing member.

  In the invention configured as described above, when the image carrier is new, the toner accumulation process is first executed, and then the period measurement process is executed. That is, the period measurement process is performed in a state where toner is deposited on the contact portion between the image carrier and the cleaning unit. Therefore, the friction between the image carrier and the cleaning unit is reduced, so that wear of the image carrier and the cleaning unit can be suppressed, and the life of the apparatus can be extended and the running cost can be reduced. In addition, since the period measurement process is executed in substantially the same state as the actual operation state of the apparatus, it is possible to accurately perform registration control based on the measurement result. This also applies to the case where the cleaning means is new.

  In the image forming apparatus configured as described above, the cleaning unit is configured to be able to come into contact with and separate from the image carrier, and the control unit applies to the image carrier in the period measurement process. The rotation period of the image carrier may be measured at each of a plurality of turns with different contact states of the cleaning unit, and the registration control may be performed based on the measurement results. When the cleaning unit comes into contact with and separates from the image carrier, the rotation cycle of the image carrier may vary due to a change in the contact state. Therefore, by performing period measurement while changing the contact state of the cleaning means to the image carrier and reflecting the result in the resist control, the resist control can be performed with high accuracy.

  For example, the rotation that keeps the cleaning unit in contact with the image carrier, the rotation that keeps the cleaning unit separated from the image carrier, and the cleaning on the image carrier during the rotation. The rotation period of the image carrier can be measured in each of the rotation in which the means is brought into contact and the rotation in which the cleaning unit is separated from the image carrier in the middle of the rotation. If the rotation period of the image carrier is measured for each of these laps, the effect on the rotation of the image carrier due to the separation and contact of the cleaning means can be accurately estimated, and the result is reflected in the resist control. Thus, the accuracy of resist control can be further improved.

  By the way, when the surface area on the surface of the image carrier on which a toner image is formed in a normal image forming operation is the image formation area, and the direction perpendicular to the moving direction of the image carrier is the width direction, The toner image is preferably formed in a strip shape extending along the width direction, and the length of the toner accumulation toner image in the width direction is longer than the length of the image forming region in the width direction. . However, it is more preferable that the length of the toner image for toner accumulation in the width direction is smaller than the length of the cleaning unit in the width direction. By so doing, toner can be deposited over a wide range of the area where the image carrier and the cleaning means abut. In particular, in a region outside the image forming region in the width direction, it is not expected that a necessary amount of toner is supplied by a normal image forming operation, and damage is particularly likely to occur at the end of the cleaning unit. Therefore, the effect of first supplying toner to this region is great.

  The image carrier may be an intermediate transfer medium that conveys the toner image formed by the image forming unit to a predetermined position and transfers it to a recording material. In an apparatus having such a configuration, in order to transfer an image to a correct position on a recording material, it is necessary to appropriately maintain the image forming position on the intermediate transfer medium. The above-described effects become particularly remarkable when applying. In particular, in an apparatus using a flexible endless belt-shaped intermediate transfer medium, if the friction with the cleaning means is large, uneven rotation due to expansion and contraction of the belt is likely to occur. It is desirable to deposit toner in advance on the contact portion.

  The image forming unit may include a plurality of developing units that store toners of different colors, and a color image may be formed by superimposing the toner images of the respective colors on the image carrier. Good. In such an apparatus, in order to form a color image with good image quality, it is necessary to superimpose toner images of respective colors on the image carrier with high positional accuracy, and the present invention is applied to such an apparatus. Thus, excellent image quality can be obtained.

  FIG. 1 is a view showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus forms a full color image by superposing four color toners (developers) of yellow (Y), cyan (C), magenta (M), and black (K), or only black (K) toner. The image forming apparatus forms a monochrome image using In this image forming apparatus, when an image signal is given to the main controller 11 from an external device such as a host computer, the CPU 101 provided in the engine controller 10 controls each part of the engine unit EG in response to a command from the main controller 11. Then, a predetermined image forming operation is executed, and an image corresponding to the image signal is formed on the sheet S.

  In the engine unit EG, the photosensitive member 22 is provided to be rotatable in the arrow direction D1 in FIG. A charging unit 23, a rotary developing unit 4 and a cleaning unit 25 are arranged around the photosensitive member 22 along the rotation direction D1. The charging unit 23 is applied with a predetermined charging bias, and uniformly charges the outer peripheral surface of the photoconductor 22 to a predetermined surface potential. The cleaning unit 25 removes the toner remaining on the surface of the photosensitive member 22 after the primary transfer, and collects it in a waste toner tank provided inside. The photosensitive member 22, the charging unit 23, and the cleaning unit 25 integrally constitute the photosensitive member cartridge 2, and the photosensitive member cartridge 2 is detachably attached to the apparatus main body as a whole.

  Then, the light beam L is irradiated from the exposure unit 6 toward the outer peripheral surface of the photosensitive member 22 charged by the charging unit 23. The exposure unit 6 exposes the light beam L onto the photosensitive member 22 in accordance with an image signal given from an external device, and forms an electrostatic latent image corresponding to the image signal.

  The electrostatic latent image thus formed is developed with toner by the developing unit 4. That is, in this embodiment, the developing unit 4 is configured as a support frame 40 that is rotatably provided about a rotation axis center orthogonal to the paper surface of FIG. A yellow developing device 4Y, a cyan developing device 4C, a magenta developing device 4M, and a black developing device 4K are provided. The developing unit 4 is controlled by the engine controller 10. Based on the control command from the engine controller 10, the developing unit 4 is driven to rotate, and the developing units 4Y, 4C, 4M, and 4K are selectively brought into contact with the photoreceptor 22 or have a predetermined gap. When positioned at a predetermined position facing each other, a developing roller 44 that is provided in the developing unit and carries toner of a selected color is disposed to face the photosensitive member 22, and at the facing position, the developing roller 44 performs photosensitive. Toner is applied to the surface of the body 22. As a result, the electrostatic latent image on the photosensitive member 22 is visualized with the selected toner color.

  The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. The transfer unit 7 includes an intermediate transfer belt 71 stretched between a plurality of rollers 72 to 75, and a drive unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction D2 by rotationally driving the roller 73. It has. When a color image is transferred to the sheet S, each color toner image formed on the photosensitive member 22 is superimposed on the intermediate transfer belt 71 to form a color image and taken out from the cassette 8 one by one. The color image is secondarily transferred onto the sheet S conveyed to the secondary transfer region TR2 along the conveyance path F.

  At this time, in order to correctly transfer the image on the intermediate transfer belt 71 to a predetermined position on the sheet S, the timing of feeding the sheet S to the secondary transfer region TR2 is managed. Specifically, a gate roller 81 is provided on the transport path F on the front side of the secondary transfer region TR2, and the gate roller 81 rotates in accordance with the timing of the circumferential movement of the intermediate transfer belt 71. S is sent to the secondary transfer region TR2 at a predetermined timing.

  Further, the sheet S on which the color image is formed in this manner is fixed with the toner image by the fixing unit 9 and is conveyed to the discharge tray portion 89 provided on the upper surface portion of the apparatus main body via the pre-discharge roller 82 and the discharge roller 83. The Further, when images are formed on both sides of the sheet S, when the rear end portion of the sheet S on which the image is formed on one side as described above is conveyed to the reversal position PR behind the pre-discharge roller 82. The rotation direction of the discharge roller 83 is reversed, whereby the sheet S is conveyed in the direction of the arrow D3 along the reverse conveyance path FR. Then, the sheet is again placed on the transport path F before the gate roller 81. At this time, the surface of the sheet S to which the image is transferred by contacting the intermediate transfer belt 71 in the secondary transfer region TR2 is first transferred. It is the opposite surface. In this way, images can be formed on both sides of the sheet S.

  A cleaner 76 is disposed in the vicinity of the roller 75. The cleaner 76 can be moved toward and away from the roller 75 by an electromagnetic clutch (not shown). Then, the blade of the cleaner 76 abuts on the surface of the intermediate transfer belt 71 that is stretched over the roller 75 while moving to the roller 75 side, and the toner that remains on the outer peripheral surface of the intermediate transfer belt 71 after the secondary transfer. Remove.

  The cleaner 76 is controlled to be separated and abutted so as to remove toner remaining on the intermediate transfer belt 71 during the same rotation as the transfer of the image onto the sheet S in the secondary transfer region TR2. . Therefore, for example, when the apparatus continuously forms monochrome images, the image transferred to the intermediate transfer belt 71 in the primary transfer region TR1 is immediately transferred to the sheet S in the secondary transfer region TR2, so that the cleaner 76 is The contact state is maintained. On the other hand, when forming a color image, the cleaner 76 needs to be separated from the intermediate transfer belt 71 while the toner images of the respective colors are superimposed on each other. Then, the toner images of the respective colors are superimposed on each other to complete a full-color image, and the cleaner 76 is brought into contact with the intermediate transfer belt 71 in order to remove residual toner in the same round as the secondary transfer onto the sheet S. It will be. The configuration and operation of the cleaner 76 will be described in detail later.

  Further, a density sensor 60 and a vertical synchronization sensor 77 are arranged in the vicinity of the roller 75. The density sensor 60 is provided to face the surface of the intermediate transfer belt 71 and measures the image density of the toner image formed on the outer peripheral surface of the intermediate transfer belt 71 as necessary. Based on the measurement result, this apparatus adjusts the operating conditions of each part of the apparatus that affects the image quality, for example, the developing bias applied to each developing cartridge, the intensity of the light beam L, and the like. The density sensor 60 is configured to output a signal corresponding to the image density of a region of a predetermined area on the intermediate transfer belt 71 using, for example, a reflection type photosensor. The CPU 101 can detect the image density of each part of the toner image on the intermediate transfer belt 71 by periodically sampling the output signal from the density sensor 60 while rotating the intermediate transfer belt 71.

  The vertical synchronization sensor 77 is a sensor for detecting the reference position of the intermediate transfer belt 71, and is used to obtain a synchronization signal output in association with the rotational driving of the intermediate transfer belt 71, that is, a vertical synchronization signal Vsync. Functions as a sensor. In this apparatus, the operation of each part of the apparatus is controlled based on the vertical synchronization signal Vsync in order to align the operation timing of each part and accurately superimpose the toner images formed in the respective colors. The vertical synchronization signal Vsync is integrated and counted by the CPU 101.

  Further, as shown in FIG. 2, each of the developing cartridges 4Y, 4C, 4M and 4K is provided with memories 91 to 94 for storing data relating to the manufacturing lot and usage history of the developing cartridge, the remaining amount of the built-in toner, and the like. ing. Further, the developing cartridges 4Y, 4C, 4M, and 4K are provided with wireless communication devices 49Y, 49C, 49M, and 49K, respectively. Then, if necessary, these selectively communicate with the wireless communication device 109 provided on the main body side in a non-contact manner, and data is transmitted between the CPU 101 and each of the memories 91 to 94 via the interface 105. Various information such as consumable management for the developing cartridge is managed by sending and receiving. In this embodiment, non-contact data transmission / reception is performed using electromagnetic means such as wireless communication. However, a connector is provided on the main body side and each developing cartridge side, and the connector is mechanically fitted. By doing so, you may make it mutually transmit / receive data.

  Further, as shown in FIG. 2, this apparatus includes a display unit 12 that is controlled by the CPU 111 of the main controller 11. The display unit 12 is constituted by, for example, a liquid crystal display, and in accordance with a control command from the CPU 111, the operation guidance to the user, the progress of the image forming operation, the occurrence of an abnormality in the apparatus, the replacement timing of any unit, etc. A predetermined message for notification is displayed.

  In FIG. 2, reference numeral 113 denotes an image memory provided in the main controller 11 for storing an image given from an external device such as a host computer via the interface 112. Reference numeral 106 is a ROM for storing a calculation program executed by the CPU 101, control data for controlling the engine unit EG, and the like. Reference numeral 107 is a RAM for temporarily storing calculation results in the CPU 101 and other data. is there.

  In addition, the image forming apparatus is used by being mounted with four developing units that store toners of different colors as described above, as well as one developing unit or a plurality of developing units that store toner of the same color. It is also used as an image forming apparatus dedicated to monochrome images in a state where the device is mounted. That is, this image forming apparatus operates as an apparatus for forming a monochrome image with the toner color in a state where only one developing device is attached. In addition, in a state where a plurality of developing devices that store toner of the same color are mounted, the apparatus operates as an apparatus that forms a monochrome image with the toner color while switching one of them or appropriately switching between them.

  FIG. 3 is a view showing the structure of the cleaner in this embodiment. As shown in FIG. 3A, the cleaner 76 is provided with a blade 763 that contacts the intermediate transfer belt 71 and scrapes off toner on an arm member 761 that is rotatable about a rotation shaft 762. The blade 763 is made of, for example, an elastic material such as urethane rubber, and is formed in a plate shape extending in the width direction orthogonal to the moving direction of the intermediate transfer belt 71 (direction orthogonal to the paper surface of FIG. 3A). A toner reservoir sheet 764 is provided on the end surface of the blade 763 opposite to the surface facing the roller 75. The toner reservoir sheet 764 is a resin sheet-like member provided so as to line the blade 763.

  The cleaner 76 configured in this manner is rotated about the rotation shaft 762 by a drive mechanism (not shown). As a result, the blade 763 is switched between a state where it is in contact with the intermediate transfer belt 71 (FIG. 3A) and a state where it is separated from the belt 71 (FIG. 3B). More specifically, when the rotation shaft 762 is driven clockwise when the cleaner 76 is in the standby position (FIG. 3B) where the blade 763 is separated from the intermediate transfer belt 71, the blade 763 moves from the left to the right in the drawing and contacts the intermediate transfer belt 71 (cleaning position, FIG. 3A). In this case, the blade tip portion moves in a substantially horizontal direction.

  The blade 763 scrapes off the toner adhering to the intermediate transfer belt 71 in contact with the intermediate transfer belt 71. As shown in FIG. 3A, the scraped toner T is disposed upstream of the contact portion between the intermediate transfer belt 71 and the blade 763 in the conveyance direction of the intermediate transfer belt 71, and the intermediate transfer belt 71 and the blade 763. The toner is accumulated in a space surrounded by the toner reservoir sheet 764. The accumulated toner T acts as a lubricant at the contact portion between the intermediate transfer belt 71 and the blade 763 to reduce frictional resistance therebetween, thereby preventing the intermediate transfer belt 71 from being worn and the blade 763 from curling. Demonstrate the effect.

  On the other hand, when the cleaner 76 moves to the standby position, the blade 763 is separated from the intermediate transfer belt 71. At this time, the toner T accumulated in the vicinity of the tip of the blade 763 falls from the blade 763 when the toner reservoir sheet is not provided. However, in this embodiment, since the toner reservoir sheet 764 is provided, the toner T Does not fall, and remains in the space (toner storage space) SP sandwiched between the blade 763 and the toner reservoir sheet 764 as shown in FIG.

  As described above, in this embodiment, even when the blade 763 is separated from the intermediate transfer belt 71, a certain amount of toner is accumulated near the tip of the blade 763. For this reason, when the blade 763 again moves toward the intermediate transfer belt 71 and hits the surface of the intermediate transfer belt 71 and stops moving, due to the reaction, the upstream side of the contact portion in the moving direction of the contact portion or the intermediate transfer belt 71 is caused. The toner T stored in the toner storage space SP is sent to the area. Due to the lubricating action of the toner, it is possible to significantly reduce the wear of the intermediate transfer belt 71 and the occurrence of wobbling of the blade 763.

FIG. 4 is a perspective view for explaining dimensions of the cleaner and the intermediate transfer belt. On the intermediate transfer belt 71, an image is not formed all the way in the width direction, but only in a predetermined image forming area (area between two broken lines in FIG. 4) 71a corresponding to the size of the sheet S. Is formed. The width of the blade 763 of the cleaner 76 is set to be larger than the width of the image forming area 71 a and smaller than the width of the intermediate transfer belt 71. That is, when the width of the intermediate transfer belt 71 is represented by the symbol Wtb, the width of the image forming area of the intermediate transfer belt 71 is represented by the symbol Wim, and the width of the blade 763 is represented by the symbol Wcl, the following relationship is established:
Wtb>Wcl> Wim
Is true.

  By making the width Wcl of the blade 763 larger than the width Wim of the image forming area 71a, it is possible to reliably remove the toner adhering to the inside of the image forming area and its peripheral portion, and to stain the image to be formed next. Is prevented. However, if the width of the blade 763 is made too large and, for example, widened to the same level as the width Wtb of the intermediate transfer belt 71, there may be a negative effect. That is, the blade 763 that contacts the intermediate transfer belt 71 serves as a load for a motor (not shown) that drives the belt 71 to rotate, and further contacts and separates from the belt 71, so that the rotation speed of the intermediate transfer belt 71 is changed. It will be a factor. In the image forming area 71a, residual toner that cannot be completely transferred to the sheet S is generated in the secondary transfer area TR2 during the image forming operation. Such toner is scraped off by the blade 763 and lubricated. Acts. On the other hand, since a small amount of such toner is present outside the image forming area 71a, the friction between the intermediate transfer belt 71 and the blade 763 increases outside the image forming area 71a. The transfer belt 71 and the blade 763 are likely to be worn or damaged. Therefore, the width Wcl of the blade 763 is desirably as small as possible, but needs to be larger than the width 71a of the image forming region.

  If the apparatus supports a plurality of types of sheets having different sizes, the width of the blade 763 may be larger than the width of the image forming area corresponding to the widest sheet. .

  Next, the width of the toner reservoir sheet will be considered. Problems, such as wear of the intermediate transfer belt 71 due to friction between the intermediate transfer belt 71 and the blade 763, and deflection of the blade 763, may occur in the entire region where both are in contact. Therefore, it is desirable that the toner reservoir sheet 764 for suppressing this also be provided all the way in the width direction of the blade 763. That is, the width of the toner reservoir sheet 764 is desirably equal to or greater than the width Wcl of the blade 763. The blade 763 may extend to the outside.

  In the apparatus configured as described above, when the apparatus is turned on, the CPU 101 executes a startup process described below in accordance with a program stored in advance in the ROM 106, whereby the apparatus performs an image formation command from the outside. Is accepted and an image can be formed.

  FIG. 5 is a flowchart showing the activation process. When the apparatus is turned on, the transfer unit 7 is first determined whether it is new or old (step S101). If the transfer unit 7 is new (step S102), the transfer unit initialization operation (step S103) and the print preparation operation (step S104) are successively performed. The transfer unit initialization operation is omitted and only the print preparation operation is performed.

  Whether or not the transfer unit 7 is new can be determined, for example, as follows. The transfer unit 7 is provided with a fuse (not shown), and a current source (not shown) capable of supplying a current sufficient to blow the fuse is provided in the apparatus main body. When a new transfer unit 7 is installed and the apparatus is turned on, a current flows from the current source to the fuse and the fuse is blown. On the other hand, if the transfer unit 7 is not new, no current flows because the fuse has already blown. That is, it is possible to determine whether the transfer unit 7 is new or old based on whether a current flows through the fuse when the power is turned on. In addition to this, for example, a memory for storing information such as a serial number and a usage history may be provided in the transfer unit 7, and the information may be read to make a new / old determination.

  FIG. 6 is a flowchart showing the transfer unit initialization operation. First, the developing unit attached to the developing unit 4 is checked (step S201). Here, (1) whether or not a developing device is mounted at each of the four developing device mounting positions provided in the developing unit 4, (2) toner color of each developing device, (3) toner in each developing device The remaining amount of toner is checked based on information stored in a memory attached to each developing device.

  Subsequently, it is determined whether or not the remaining amount of toner in the specific developing device is greater than or equal to a predetermined amount (step S202). Here, the “specific developer” is a developer for use in forming a toner image for toner accumulation in “toner accumulation processing” described later. The specific developing device can be designated in advance based on the criteria such as the toner color or the mounting position on the developing unit 4, or can be designated each time based on the result of the check. For example, a specific color developer may be designated as a “specific developer”, and the developer having the largest amount of toner among the developers attached to the development unit 4 is designated as the “specific developer”. Also good. However, since the content of subsequent processing differs depending on the remaining amount of toner in the specific developer, it is preferable that the developer that is expected to be used relatively frequently be the specific developer. Here, the black developing device is referred to as a “specific developing device”.

  When the remaining amount of toner in the specific developer is less than the predetermined amount, the toner accumulation process described later cannot be performed, and it is not expected to form an image with good image quality in this state. Stops the startup process. In this case, it is desirable to notify the user by displaying on the display unit 12 that the processing has been stopped due to insufficient toner remaining.

  On the other hand, if a predetermined amount or more of toner remains in the specific developing device, it is subsequently determined whether the apparatus is used as a color image forming apparatus or a monochrome image forming apparatus (step). S203). Here, the determination is made according to the number and type of the developing units attached to the developing unit 4. That is, when four developing devices of yellow, cyan, magenta, and black are attached to the developing unit 4, it is determined that the device is used as a color image forming apparatus. In other cases, that is, when the four color developing devices are not prepared, it is determined that the device is used as a monochrome image forming apparatus. Even when the four color developing devices are provided, if the user makes a setting to use the device as a device dedicated to monochrome images, the user is obeyed.

  When the apparatus is used as a color image forming apparatus, a toner accumulation process (step S204) and a period measurement process (step S205) described below are executed in this order. On the other hand, when the apparatus is used as a monochrome image forming apparatus, only toner accumulation processing is executed (step S206).

  FIG. 7 is a flowchart showing the toner accumulation process. In this toner accumulation process, a certain amount of toner is sent to the contact portion between the intermediate transfer belt 71 and the cleaner blade 763, and this toner acts as a lubricant to cause friction between the intermediate transfer belt 71 and the cleaner blade 763. This is a process for reducing the problem. When the intermediate transfer belt 71 is rotationally driven in a state where the cleaner blade 763 is in contact with the intermediate transfer belt 71, the cleaner blade 763 is likely to sag and the intermediate transfer belt 71 is worn due to the sliding contact therebetween. Considering this, a lubricant such as wax is applied in advance to the blade tip at the time of shipment, but the effect is gradually lost by sliding contact. In addition, when the image forming operation is performed continuously or intermittently, the toner remaining on the intermediate transfer belt 71 after the secondary transfer is sent to the contact portion with the blade 763. Toner acts as a lubricant. However, since such toner does not exist when the transfer unit 7 is new, it is desirable to send the toner to the contact portion between the intermediate transfer belt 71 and the blade 763 as early as possible. A process for this is a toner accumulation process.

  In the toner accumulation process, first, rotation driving of the intermediate transfer belt 71 is started (step S301). Next, the blade 763 provided on the cleaner 76 is brought into contact with the surface of the intermediate transfer belt 71 (step S302). At this stage, the wax applied to the blade tip acts as a lubricant. Subsequently, the engine unit EG is operated to form the toner accumulation patch image Idp shown in FIG. 8 on the intermediate transfer belt 71 (step S303).

  FIG. 8 is a diagram illustrating an example of a toner accumulation patch image. As shown in FIG. 8, the toner accumulation patch image Idp is a belt-like image extending in the width direction perpendicular to the moving direction D2 of the intermediate transfer belt 71. Although the image pattern is arbitrary, it can be a uniform solid image or a halftone image, for example, for ease of creation. The length Ldp of the toner accumulation patch image Idp along the moving direction D2 of the intermediate transfer belt 71 is necessary for supplying a sufficient amount of toner to be deposited in the toner storage space SP to the contact portion with the blade 763. Length.

  The width Wdp of the toner accumulation patch image Idp is as follows. From the standpoint of preventing the intermediate transfer belt 71 from being worn and the blade 763 from curling, it is necessary to deposit toner over the entire width of the blade 763. Therefore, it is desirable that the width Wdp of the toner accumulation patch image Idp is larger than the width Wim of the image forming region, and preferably about the same as the blade width Wcl (FIG. 4). However, since the toner adhering to the intermediate transfer belt 71 beyond the blade width cannot be removed by the cleaner 76, the width Wdp of the toner accumulation patch image Idp should not be larger than the blade width Wcl. It can also be expected that a part of the scraped toner spreads outside the width of the toner accumulation patch image in the toner storage space SP. Therefore, the width Wdp of the toner accumulation patch image Idp is preferably larger than the width Wim of the image forming area and slightly smaller than the width Wcl of the blade.

  The toner accumulation patch image Idp is scraped off by the blade 763 in contact with the intermediate transfer belt 71, so that the toner can be accumulated in the toner storage space SP at the tip of the blade 763. It acts to effectively prevent the belt 71 and the blade 763 from being damaged or worn.

  FIG. 9 is a diagram showing a process for measuring the period of the intermediate transfer belt. FIG. 10 is a timing chart showing the principle of period measurement. In the period measurement process, the intermediate transfer belt 71 is rotated with the cleaner blade 763 in contact (step S401). And the rotation period is measured in each round. In the first round, the blade 763 in the contact state is separated halfway and the rotation period T11 is measured (step S402). The rotation cycle of the intermediate transfer belt 71 can be obtained as the rising cycle of the vertical synchronization signal Vsync output from the vertical synchronization sensor 77 in synchronization with the rotation. In the next round, the rotation period T21 is measured while maintaining the separated state (step S403). In the third round, the blade 763 is brought into contact with the intermediate transfer belt 71 from the middle to measure the rotation period T31 (step S404). In the fourth round, the rotation period T41 is measured while maintaining the contact state (step S405). The period measurement is repeated a predetermined number of times, for example, 10 sets, with 4 rounds as one set (step S406).

  From the rotation period thus measured, the registration control amount at the time of color image formation is calculated (step S407). The registration control amount here is a shift amount of the transfer start position when the toner image is primarily transferred from the photosensitive member 22 onto the intermediate transfer belt 71. The rotation cycle of the intermediate transfer belt 71 varies due to the expansion and contraction of the belt accompanying the separation and contact of the blade 763 and the load variation on the motor. Typically, the rotation period T41 in the rotation with the blade 763 kept in contact tends to be longer than the rotation period T21 in the rotation with the blade 763 spaced apart. Further, the rotation periods T11 and T31 in the rotation in which the blade 763 is separated in the middle or brought into contact with the middle are longer than the period T21 and shorter than the period T41. From these measurement results, the degree of fluctuation in the rotational speed of the intermediate transfer belt 71 due to the contact of the blade 763 can be estimated. In this embodiment, in order to reduce the measurement error of the rotation period of the intermediate transfer belt 71 and increase the accuracy of registration control, the period measurement in each contact state is performed a plurality of times (in the above example, 10 times), The registration control amount is calculated from the average value of the measured values (for example, for the lap in which the blade is separated halfway, the cycle T11 of the first cycle, the cycle T12 of the fifth cycle,...).

  Variations in the rotational speed of the intermediate transfer belt 71 cause positional deviation (registration deviation) of the toner images of the respective colors, resulting in a decrease in image quality. Therefore, when the toner images of the respective colors are formed, the transfer start position of the toner image is adjusted according to the contact state of the blade 763 with the intermediate transfer belt 71 when the toner image is formed. It is possible to prevent color misalignment and form a color image with excellent image quality. There is a publicly known technique for such a specific method of resist control, and the technique described in, for example, Japanese Patent Application Laid-Open No. 2001-235924 can also be applied to this embodiment. Omitted.

  The above-described rotation period measurement of the intermediate transfer belt 71 is performed following the toner accumulation process as shown in FIG. Therefore, toner is accumulated at the contact portion between the intermediate transfer belt 71 and the blade 763 at the time of measuring the rotation period. This not only prevents the blade 763 from curling and the intermediate transfer belt 71 from being worn during the period measurement process, but also contributes to improving the accuracy of resist control. This is because the period of rotation of the intermediate transfer belt 71 in a state close to the actual image forming operation can be obtained by performing the period measurement in a state where the toner is accumulated on the blade tip. If toner accumulation processing is not performed in advance, measurement is performed under conditions different from those during actual image formation, and the accuracy of resist control decreases. This is the same even if wax or the like is previously applied to the blade.

  When the apparatus is used as an apparatus dedicated to monochrome images, the toner images are not superimposed on the intermediate transfer belt 71. Therefore, it is necessary to perform registration control and period measurement processing as preparation work thereof. Absent. Therefore, when the apparatus is used as a monochrome image forming apparatus, the processing time can be significantly shortened by omitting the period measurement process.

  FIG. 11 is a flowchart showing the print preparation operation. In this operation, in order to maintain a predetermined image quality, an operation parameter that affects the image quality is adjusted. In this embodiment, the development bias and the exposure power are used as the operation parameters described above, and these parameters are optimized based on the density detection result of the toner image formed as a patch image. It should be noted that there are many known techniques other than those described here for parameters that affect image quality and their adjustment methods, and these can also be applied in this embodiment. Only a brief explanation. Although omitted in FIG. 11, a warm-up operation for raising the temperature of the fixing unit 9 to a predetermined fixing temperature is also performed in parallel with the optimization of the parameters.

  In the print preparation operation, first, the development bias is optimized (steps S501 to S505). More specifically, first, the one developing device is moved to a developing position facing the photosensitive member 22 (step S501). A predetermined patch image is formed with each bias value while variously changing the developing bias applied to the developing device (step S502). The density of these patch images transferred to the intermediate transfer belt 71 is detected by the density sensor 60 (step S503), and the optimum value of the developing bias at which the patch image density matches a predetermined target density is calculated from the measurement results. (Step S504). This series of processing is repeated until all necessary developing devices are completed (step S505). In a color image forming apparatus, it is necessary to obtain an optimum developing bias for all of the four color developing devices. On the other hand, in a monochrome image forming apparatus, it is not always necessary to perform processing for all the developing devices, and it is possible to form a monochrome image by optimizing at least one developing device.

  Subsequently, the exposure power when exposing the photosensitive member 22 by the exposure unit 6 is optimized (steps S506 to S510). First, one developing device is moved to a developing position facing the photosensitive member 22 (step S506). Then, a predetermined patch image is formed with each power while varying the exposure power from the exposure unit 6 (step S507). At this time, the developing bias is set to the optimum value obtained previously. In the same manner as described above, the density of these patch images is detected by the density sensor 60 (step S508), and the optimum value of the exposure power is calculated from the measurement results (step S509). This series of processing is repeated until all necessary developing devices are completed (step S510).

  This optimizes the development bias and exposure power for each developer used for image formation. In the subsequent image forming operation, by setting the developing bias and the exposure power to the optimum values thus obtained, it is possible to stably form an image with good image quality.

  As described above, in this embodiment, when the transfer unit 7 including the intermediate transfer belt 71 and the cleaner 76 is new, the initialization process for making the transfer unit 7 usable is performed. In this case, the content of the initialization process varies depending on whether the apparatus is used as a color image forming apparatus or a monochrome image forming apparatus at the time of execution of the initialization process. More specifically, in the color image forming apparatus, an initialization process for executing the toner accumulation process and the period measurement process in this order is performed, and then a printing preparation operation is performed. On the other hand, in the monochrome image forming apparatus, the print preparation operation is performed after performing the initialization process including the toner accumulation process and not including the period measurement process. In this way, by changing the contents of the initialization process depending on whether the device is in color or monochrome, it is possible to execute the initialization process according to each operation state, and the contents of the initialization process are uniform. Therefore, the initialization process can be performed more efficiently than the conventional technique.

  The toner accumulation process is performed by forming a belt-like image extending in the width direction orthogonal to the moving direction D 2 of the intermediate transfer belt 71 on the intermediate transfer belt 71 and scraping it off with a blade 763. Therefore, a special configuration for depositing toner is not required. When the transfer unit 7 is new, toner accumulation processing is performed prior to other operations, so that the intermediate transfer belt 71 and the blade 763 are not in sliding contact with a large amount of friction for a long time. 71 and cleaner 76 can be effectively prevented from being worn or damaged.

  Further, in the registration control in this embodiment, the contact state between the blade 763 and the intermediate transfer belt 71 is changed to four ways (separated from the contact, kept apart, contacted from the contact, and kept in contact), respectively. Since the rotation period in each of the rotations is individually measured and the resist control amount is obtained from the measurement results, the toner images can be superimposed with high accuracy.

  The period measurement process is executed when the transfer unit 7 is new, but the period measurement is performed in a state where toner is deposited on the contact portion between the intermediate transfer belt 71 and the blade 763. Therefore, measurement is performed in a state close to the actual image formation, and the accuracy of resist control can be further improved. In the period measurement process, the blade 763 is repeatedly contacted with the intermediate transfer belt 71, and the blade 763 is likely to be swollen. However, by preliminarily depositing the toner, the risk is greatly reduced. ing.

  Here, as a special case, consider a case where the initialization process of the transfer unit 7 is performed when the apparatus is used as a monochrome image forming apparatus, and then the apparatus is switched to a color image forming apparatus. Such switching of the use state of the apparatus is realized, for example, by replacing the developing device after the end of the initialization process. Thus, the apparatus switches to a color image forming apparatus, but it is not appropriate to immediately form a color image in this state. This is because the period of the intermediate transfer belt 71 necessary for resist control is not measured. Therefore, when the apparatus is switched from monochrome to a color image forming apparatus and the period measurement process using the current transfer unit 7 has not yet been performed, it is necessary to perform the period measurement process prior to image formation. .

  For example, the following two modes may be considered as the period measurement process. In the first aspect, when the apparatus is switched to the color image forming apparatus, the same initialization process as when the transfer unit 7 is new is performed. That is, when the color image forming apparatus is switched, the transfer unit initialization process shown in FIG. 6 is executed to perform the toner accumulation process and the period measurement process. In such a process, the conditions for entering the transfer unit initialization operation in the start-up process shown in FIG. 5 are “when the transfer unit is new”, “when the transfer unit is new, or the apparatus is switched to the color image forming apparatus”. It can be realized by changing to “when”.

  In the second aspect, the period measurement process is performed without the toner accumulation process. When the apparatus is switched to the color image forming apparatus during use, it is generally considered that the transfer unit 7 is not new, and a certain amount of toner is already accumulated on the blade 763. By omitting, processing time can be shortened and toner can be saved.

  In any case, when the device is switched from monochrome to color, it is desirable to perform a period measurement process prior to the formation of the color image and to reflect the result in the resist control. Therefore, it is possible to form an image with good image quality. When the transfer unit 7 is new and is used as a monochrome image forming apparatus by user setting even though the four color developing devices are prepared, the period measurement is performed at that time in advance. Processing may be performed, or the period measurement processing may be performed again when necessary (that is, when the user setting is changed to color). In the case of the former, a color image can be formed immediately when the user setting is changed. In the latter case, the time required for the startup process at the time of a new product can be shortened.

  As described above, in this embodiment, the intermediate transfer belt 71 and the cleaner 76 function as the “image carrier” and “cleaning unit” of the present invention, respectively. Further, the photosensitive member 22, the exposure unit 6, the developing unit 4 and the like function as an “image forming unit” of the invention. The engine controller 10 functions as a “control unit” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the print preparation operation is performed following the transfer unit initialization operation. However, in the present invention, the print preparation operation is not essential, and may be omitted or the transfer unit may be initialized. Other processing operations may be added as appropriate before or after.

  Further, in the above-described embodiment, the transfer unit new / old determination is performed only immediately after the power of the apparatus is turned on. However, the present invention is not limited to this. For example, the determination may be performed constantly. However, if the unit replacement is performed only when the power is turned off, it is sufficient to perform the determination only when the power is turned on as in the present embodiment.

  In the above-described embodiment, the intermediate transfer belt 71 and the cleaner 76 integrally constitute a transfer unit 7 that can be attached to and detached from the apparatus main body. However, the intermediate transfer belt and the cleaner constitute separate units. Also good. In this case, the toner accumulation process should be executed when at least one of the intermediate transfer belt and the cleaner is new. The period measurement process should be executed at least when the intermediate transfer belt is new.

  The above embodiment is an image forming apparatus provided with an intermediate transfer belt as an image carrier, but the present invention can be applied to other forms, for example, an apparatus provided with a drum-shaped image carrier. Is possible. It is also possible to apply the present invention with the photoconductor as an “image carrier”. In particular, in an apparatus configured to adjust the image forming position on the photoconductor for resist control, the same effect as described above can be obtained by treating the photoconductor as the “image carrier” of the present invention. be able to.

  Further, the present invention is not only an apparatus including a rotary developing unit as in the above-described embodiment, but also a so-called tandem image forming apparatus and an image forming apparatus that forms an image based on a principle other than an electrophotographic system, The present invention can be applied to all image forming apparatuses that include an image carrier that temporarily carries a toner image, and a cleaning unit that contacts the toner carrier and removes toner.

1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus in FIG. 1. The figure which shows the structure of the cleaner in this embodiment. FIG. 4 is a perspective view for explaining dimensions of the cleaner and the intermediate transfer belt. The flowchart which shows a starting process. 6 is a flowchart showing a transfer unit initialization operation. 6 is a flowchart showing toner accumulation processing. FIG. 6 is a diagram illustrating an example of a toner accumulation patch image. The figure which shows the period measurement process of an intermediate transfer belt. The timing chart which shows the principle of period measurement. 6 is a flowchart showing a print preparation operation.

Explanation of symbols

  4 ... development unit (image forming means), 4C, 4K, 4M, 4Y ... developer, 6 ... exposure unit (image forming means), 10 ... engine controller (control means), 22 ... photosensitive member (image forming means), 7: Transfer unit 71: Intermediate transfer belt (image carrier) 76: Cleaner (cleaning means) 77: Vertical synchronization sensor

Claims (8)

An image carrier configured to carry a toner image on its surface and moving around in a predetermined direction;
Image forming means for forming a toner image and carrying the toner image on the surface of the image carrier;
Cleaning means for removing residual toner on the surface of the image carrier in contact with the image carrier;
Control means for performing resist control for controlling an image forming position on the image carrier by the image forming means,
When the control means determines that the image carrier is new,
A toner image for toner deposition having a predetermined pattern is formed on the image carrier by the image forming unit, and the toner image is sent to a contact part between the image carrier and the cleaning unit, and the toner is applied to the corresponding part. A toner deposition process for depositing;
A cycle measurement process for measuring a rotation period of the image carrier when the image carrier is rotated is performed in this order, and the resist control is performed based on a measurement result in the cycle measurement process. Image forming apparatus. An image carrier configured to carry a toner image on its surface and moving around in a predetermined direction;
Image forming means for forming a toner image and carrying the toner image on the surface of the image carrier;
Cleaning means for removing residual toner on the surface of the image carrier in contact with the image carrier;
Control means for performing resist control for controlling an image forming position on the image carrier by the image forming means,
The control means executes a new article determination process for determining whether or not the image carrier is new when the apparatus is turned on, and determines that the image carrier is new.
A toner image for toner deposition having a predetermined pattern is formed on the image carrier by the image forming unit, and the toner image is sent to a contact part between the image carrier and the cleaning unit, and the toner is applied to the corresponding part. A toner deposition process for depositing;
A cycle measurement process for measuring a rotation period of the image carrier when the image carrier is rotated is performed in this order, and the resist control is performed based on a measurement result in the cycle measurement process. Image forming apparatus. The cleaning means is configured to be able to separate and come into contact with the image carrier,
In the period measurement process, the control unit measures the rotation period of the image carrier at each of a plurality of turns with different contact states of the cleaning unit to the image carrier, and the measurement results The image forming apparatus according to claim 1, wherein the registration control is performed based on the image forming apparatus. The control means includes
The rotation of the image carrier with the cleaning means held in contact with the image carrier, the rotation of the image carrier with the cleaning means spaced apart from the image carrier, and the rotation of the cleaning means to the image carrier during the rotation. 4. The image forming apparatus according to claim 3, wherein the rotation period of the image carrier is measured in each of the contacted rotation and the rotation in which the cleaning unit is separated from the image carrier during the rotation. When the surface area on which the toner image is formed in the normal image forming operation on the surface of the image carrier is an image formation area, and the direction perpendicular to the moving direction of the image carrier is a width direction,
The toner accumulation toner image is formed in a strip shape extending in the width direction, and the length of the toner accumulation toner image in the width direction is longer than the length of the image formation region in the width direction. The image forming apparatus according to claim 1.   6. The image forming apparatus according to claim 1, wherein the image carrier is an intermediate transfer medium that conveys the toner image formed by the image forming unit to a predetermined position and transfers the toner image to a recording material.   6. The image forming device according to claim 1, wherein the image forming unit includes a plurality of developing units that store toners of different colors, and forms a color image by superimposing the toner images of the respective colors on the image carrier. The image forming apparatus described in 1. A toner image can be carried on the surface, and an image carrier that circulates in a predetermined direction. The image carrier can be separated from and contacted with the image carrier, and the image carrier is in contact with the image carrier. In an image forming method using an image forming apparatus including a cleaning unit that removes residual toner on a body surface,
When the image carrier is new,
A toner image for toner deposition having a predetermined pattern is formed on the image carrier by the image forming unit, and the toner image is sent to a contact part between the image carrier and the cleaning unit, and the toner is applied to the corresponding part. A toner deposition process for depositing;
Period measurement processing for measuring the rotation period of the image carrier when the image carrier is rotated in a state where the cleaning unit is in contact with the image carrier is performed in this order,
An image forming method comprising: performing resist control for controlling an image forming position on the image carrier based on a measurement result in the period measurement process when forming an image.

Images