JP2007121741A - Image forming apparatus and method for controlling same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which eliminates a speed fluctuation factor occurring during the adjustment of phases of photosensitive drums thereby stabilizing the transport speed of an electrostatic transfer transport belt and outputs, as a result, a stable image of high picture quality having no out-of color registration, and to provide a method for controlling the image forming apparatus. <P>SOLUTION: The image forming apparatus comprises the plurality of photosensitive drums 1a, 1b, 1c and 1d and a transfer transport belt 12 for transferring toner images formed on the plurality of photosensitive drums to a transfer material, wherein the transfer transport belt 12 is controlled so as to be rotationally driven at a speed different from the rotational speed of the plurality of photosensitive drums during the adjustment of the rotational phases of the photosensitive drums. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a color copying machine, a color printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, and a control method for the image forming apparatus.

  In an image forming apparatus using an electrophotographic system, a process cartridge system in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge and the cartridge can be attached to and detached from the image forming apparatus main body. Is adopted. According to this process cartridge system, since the user can perform maintenance of the apparatus by himself / herself without depending on the service person, the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

  Here, an electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer or an LED printer), a facsimile machine, and the like.

  In the process cartridge system described above, at least one of charging means, developing means, or cleaning means is integrally formed with an electrophotographic photosensitive member, and this cartridge can be attached to and detached from the image forming apparatus main body. Say what you want.

  Conventionally, there is a color image forming apparatus called a so-called in-line system in which a plurality of photosensitive drums are arranged in a line. This is because an image is transferred to a transfer material by four photosensitive drums arranged along a transfer material conveyance path while the transfer material is carried and conveyed by an electrostatic transfer conveyance belt stretched by a plurality of rollers. It is a method. A toner image composed of yellow, magenta, cyan, and black is sequentially transferred onto a transfer material by four photosensitive drums, and a color image is formed by superimposing each color. This configuration has attracted attention in recent years because it can perform color printing at high speed, and an inline configuration is generally used in color image forming apparatuses.

  However, since each color is formed by the four photosensitive drums, higher accuracy is required for rotational driving of the photosensitive drum than in the conventional method. In addition, as a conventionally known configuration, color image formation of a configuration in which colors are superimposed on each photosensitive drum via four transport passes for each color (hereinafter simply referred to as “four-pass method”). There is a device.

  Further, in this type of inline apparatus, the image forming mechanism is unitized to form a process cartridge that can be detached from the main body of the image forming apparatus, thereby facilitating maintenance.

  In general, a drive gear train is employed for driving the photosensitive drum, and low-frequency rotation unevenness such as one rotation component of the gear always occurs. However, in the case of the conventional 4-pass system, the reduction ratio of the drive gear train is a combination of integers, so that the cumulative pitch error of the gears can be avoided and the image forming positions of the respective colors can be matched. .

  However, in the case of the in-line method, since the plurality of photosensitive drums are independent, the drive gear train is also independent, and it is difficult to avoid such a problem as in the 4-pass method described above. Accordingly, image quality deterioration called color misregistration due to misalignment of the image forming position of each color is more likely to occur than in the conventional method.

  Therefore, conventionally, as countermeasures for color misregistration, the angular speed of the photosensitive drum is detected, or the image transferred onto the transfer material is read to detect the speed unevenness, and the motor is rotated so as to cancel the speed unevenness. Measures to control are taken. Further, as disclosed in Patent Document 1, Patent Document 2, and the like, measures have been taken to reduce relative color misregistration by matching the rotational phase of each photosensitive drum to a desired state.

  By the way, a color image forming apparatus and an image quality adjustment system capable of greatly reducing color misregistration by a method of easily detecting unevenness in angular velocity of the photosensitive drum and adjusting the rotational phase of each photosensitive drum have been provided. Yes.

  In this case, in order to adjust the rotational phase of each photosensitive drum to a desired state, an image transferred to the transfer material of the photosensitive drum is read. In the detection method for detecting the angular velocity unevenness, the phase of each photoconductor drum is controlled, and by detecting the speed nonuniformity corresponding to the phase of the photoconductor drum, the photoconductor drum phase for determining the optimum phase for color misregistration. There are adjustment methods.

  In addition, there is an apparatus that realizes image formation by performing different operations in a color image forming method and a monocolor image forming method in the same main body.

  An example is shown in FIG. The color image forming apparatus shown in the figure includes process cartridges 7a, 7b, 7c, and 7d that are detachable from the image forming apparatus main body A. These four process cartridges 7a, 7b, 7c, and 7d have the same structure, but images of toners of different colors, that is, yellow (Y), magenta (M), cyan (C), and black (Bk) are displayed. It differs in the point to form.

  The process cartridges 7a, 7b, 7c, 7d are constituted by drum units 5a, 5b, 5c, 5d and developing units 4a, 4b, 4c, 4d. Among these, the former drum units 5a, 5b, 5c, and 5d include photosensitive drums 1a, 1b, 1c, and 1d that are image carriers, charging rollers 2a, 2b, 2c, and 2d, a cleaner, and a toner container. Have.

  The latter developing units 4a, 4b, 4c, and 4d include developing rollers 40a, 40b, 40c, and 40d, toner charging rollers 61a, 61b, 61c, and 61d, a developer applying roller, and a developer applying blade. is doing. The developing units 4a, 4b, 4c, and 4d are swingable with respect to the drum units 5a, 5b, 5c, and 5d around the support shafts 49a, 49b, 49c, and 49d. The suspension structure is supported by.

  In this structure, ribs 46a, 46b, 46c, 46d provided on the developing units 4a, 4b, 4c, 4d are provided with separation plates 8M, 8C. By moving the separation plate up and down, the developing rollers 40a, 40b, 40c, and 40d can be brought into contact with and separated from the photosensitive drums 1a, 1b, 1c, and 1d. Scanner units 3a, 3b, 3c, and 3d are arranged substantially horizontally in the process cartridges 7a, 7b, 7c, and 7d, and exposure based on image signals is performed on the photosensitive drums 1a, 1b, 1c, and 1d. The latent images formed on the photosensitive drums 1a, 1b, 1c, and 1d are developed by the developing units 4a, 4b, 4c, and 4d to form toner images. The toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d are sequentially transferred onto a transfer material (transfer object) P supplied by the feeding / conveying device 17. The feeding / conveying device 17 includes a paper feeding roller 9 that feeds the transfer material P from the paper feeding cassette 11 that houses the transfer material P, and a transporting roller 10 that transports the fed transfer material P. . Then, the transfer material P conveyed from the feeding / conveying device 17 is adsorbed to the surface of the electrostatic transfer conveyance belt 12 by the adsorption roller 18.

  The electrostatic transfer / conveying belt 12 is stretched around a suction-facing roller 21, an electrostatic transfer / conveying belt driving roller 22, and tension rollers 23 and 24. The transfer material P is carried on the surface and rotates in the direction of arrow R12. The toner images of the respective colors Y, M, C, and Bk formed on the above-described photosensitive drums 1a, 1b, 1c, and 1d are superimposed on the transfer material P on the electrostatic transfer conveyance belt 12. Specifically, images are sequentially transferred onto the transfer material and superimposed by transfer rollers (transfer members) 6a, 6b, 6c, and 6d disposed on the inner surface of the electrostatic transfer conveyance belt 12. After transfer of the toner image, the transfer material P is separated from the electrostatic transfer conveyance belt 12 and conveyed to the fixing device 14 where it is heated and pressurized to fix the toner image on the surface.

  This type of image forming apparatus has a full-color mode in which a full-color image is formed using four color toners and a mono-color mode in which a mono-color image is formed using only Bk toner. In the full color mode, the separation plates 8M and 8C press down the ribs 46a, 46b, 46c and 46d to bring the developing rollers 40a, 40b, 40c and 40d into contact with the photosensitive drums 1a, 1b, 1c and 1d, respectively. On the other hand, in the mono color mode, only the developing roller 40d is brought into contact with the photosensitive drum 1d by pushing down only the rib 46d. Thereby, when printing a monochromatic image, the rotation can be stopped without bringing the color developing rollers 40a, 40b, and 40c into contact with the photosensitive drums 1a, 1b, and 1c.

  Since the life of the developing device depends on the number of rotations of the developing roller, stopping the rotation of the color developing rollers 40a, 40b, and 40c prevents the life of the color developing device from being shortened for monocolor image printing. be able to. Further, since the color developing rollers 40a, 40b, and 40c are separated from the photosensitive drums 1a, 1b, and 1c, it is not necessary to charge the photosensitive drums 1a, 1b, and 1c. Generally, since the surface of the photosensitive drum is scraped by discharge during charging, the life of the photosensitive drum can be improved by turning off the charging while rotating the photosensitive drums 1a, 1b, and 1c in the mono-color mode.

  The toner charging rollers 61a, 61b, 61c, and 61d are used for charging the toner on the developing rollers 40a, 40b, 40c, and 40d so that the toner has a high tribo uniformly.

  However, as the image formation continues, the polarity-reversed toner and the nonpolar toner adhere to the toner charging rollers 61a, 61b, 61c, and 61d as contaminated toner. When such contaminated toner adheres, the charging capability inherent to the toner charging roller cannot be exhibited.

  Therefore, a cleaning bias is applied at the timing of pre-rotation before image exposure is performed during image formation (printing). Patent Document 3, Patent Document 4 and the like propose a method for removing contaminated toner adhering to the toner charging rollers 61a, 61b, 61c, and 61d by applying this bias. In this way, the toner can always be stably charged.

Further, in the above-described monocolor mode, there is a type that performs image formation by bringing only the photosensitive drum 1d into contact with the above-described electrostatic transfer conveyance belt 12. In that case, the surface of the photosensitive drums 1a to 1c can be further prevented from being scraped than the above-described method, and the life of the photosensitive drum can be further improved.
JP-A-9-146329 JP-A-10-333398 JP 2001-159844 A JP 2001-242709 A

  However, the electrostatic transfer / conveying belt 12 of the color image forming apparatus described above is an electrostatic conveying belt that is stretched around four rollers, that is, an adsorption facing roller 21, an electrostatic transfer / conveying belt driving roller 22, and tension rollers 23 and 24. 12 is disposed. The electrostatic conveyance belt 12 is disposed so as to circulate and move so as to face the photosensitive drums 1a, 1b, 1c, and 1d.

  The electrostatic transfer / conveying belt 12 is made of a resin material such as PVdF (polyvinylidene fluoride), polyamide, polyimide, PET (polyethylene terephthalate), or polycarbonate having a thickness of 50 to 300 μm and a volume resistivity of 109 to 1016 Ω · cm. Also, rubber such as chloroprene rubber, EPDM (ethylene-propylene-diene terpolymer), NBR (nitrile butadiene rubber), urethane rubber, etc. having a thickness of 0.5-2 mm and volume resistivity of 109-1016 Ω · cm Materials are also used. Further, if necessary, conductive fillers such as carbon, ZnO, SnO2, and TiO2 may be dispersed in these materials to adjust the volume resistivity to about 107 to 1011 Ω · cm.

  Since the electrostatic transfer / conveying belt 12 is made of the above-described material, the surface of the electrostatic transfer / conveying belt 12 is coated immediately after manufacture, and the uniformity is very good. Therefore, when the friction coefficient between the inner surface of the transfer belt 12 and the surface of the transfer belt 12 at the initial stage of manufacture is compared, there may be a large difference due to the difference in surface properties.

  For this reason, since the static friction coefficient and the dynamic friction coefficient of the inner surface of the electrostatic transfer / conveyance belt 12 and the electrostatic transfer / conveyance belt drive roller 22 are not stable, the rotational drive load characteristics may vary. Further, the static friction coefficient and the dynamic friction coefficient between the surface of the electrostatic transfer conveyance belt 12 and the photosensitive drums 1a, 1b, 1c, and 1d are not stable and the same phenomenon occurs. Therefore, the following problems occur.

  That is, the speed of the electrostatic transfer conveyance belt 12 is determined not only by the driving force of the driving roller 22 that drives the electrostatic transfer conveyance belt 12, but also by the rotational force of the photosensitive drums 1a to 1d and the transfer roller (inside the electrostatic transfer conveyance belt 12). The transfer member is easily affected by the nip pressure of the transfer members 6a to 6d. And the phenomenon that the moving speed of the electrostatic transfer conveyance belt 12 is not stable occurs.

  If the grip force for transporting either one of the electrostatic transfer and transport belts 12 is insufficient, a phenomenon such as slip or minute slack occurs in the direction with the lowest worst friction coefficient. As a result, the conveyance speed of the electrostatic transfer conveyance belt 12 is significantly affected by the difference in rotational speed generated during the phase control of the photosensitive drums 1a to 1d. There is a possibility that the moving speed of the transfer / conveying belt 12 is difficult to stabilize.

  If the speed is not stable, image formation is started, and the toner images of each color Y, M, C, and Bk formed on the photosensitive drums 1a to 1d are sequentially transferred onto the transfer material P by the transfer rollers 6a to 6d. However, there is a possibility that color misregistration occurs in the image on the transfer material P.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of outputting a stable high-quality image without color misregistration and a method for controlling the image forming apparatus. It is.

  In order to achieve the above object, an image forming apparatus of the present invention includes a plurality of image carriers, and a transfer conveyance unit for transferring images formed on the plurality of image carriers to a transfer material. An image forming apparatus comprising: a phase adjusting unit configured to adjust a rotational phase of the plurality of image carriers; and a phase adjusting unit configured to adjust the rotational phases of the plurality of image carriers by the phase adjusting unit. And speed control means for controlling the transfer conveyance means to rotate at a speed different from the rotational speed.

  Another image forming apparatus of the present invention is an image forming apparatus having a plurality of image carriers and intermediate transfer means for supporting images formed on the plurality of image carriers. A phase adjusting unit that adjusts a rotational phase of the plurality of image carriers, and a phase different from the rotational speed of the plurality of image carriers during the phase adjustment of the plurality of image carriers by the phase adjusting unit; And a speed control means for controlling the intermediate transfer means to rotate.

  According to another aspect of the present invention, there is provided a control method for an image forming apparatus, comprising: a plurality of image carriers; and a transfer conveying unit for transferring an image formed on the plurality of image carriers to a transfer material. The phase adjustment step of adjusting the rotation phase of the plurality of image carriers and the rotation speed of the plurality of image carriers during the adjustment of the rotation phase of the plurality of image carriers are different from each other. And a speed control step for controlling the transfer conveying means to rotate at a speed.

  According to another aspect of the present invention, there is provided a control method for an image forming apparatus, comprising: a plurality of image carriers; and an intermediate transfer unit for supporting images formed on the plurality of image carriers. A control method comprising: a phase adjustment step for adjusting a rotation phase of the plurality of image carriers; and a speed different from a rotation speed of the plurality of image carriers during the adjustment of the rotation phase of the plurality of image carriers. And a speed control step for controlling the intermediate transfer means to rotate.

  As described above, according to the present invention, it is possible to provide an image forming apparatus and an image forming apparatus control method capable of outputting a high-quality image without causing color misregistration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent. In addition, what attached | subjected the same code | symbol in each drawing has the same structure or effect | action, The duplication description about these was abbreviate | omitted suitably.

  With reference to FIG. 1, an image forming apparatus according to Embodiment 1 of the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing the entire configuration of a full-color laser beam printer which is an aspect of the image forming apparatus according to the first embodiment. With reference to the figure, first, an outline of the overall configuration of the image forming apparatus will be described.

[overall structure]
The image forming apparatus shown in the figure includes process cartridges 7a, 7b, 7c, and 7d that are detachable from the image forming apparatus main body A. These four process cartridges 7a, 7b, 7c, and 7d have the same structure, but images of toners of different colors, that is, yellow (Y), magenta (M), cyan (C), and black (Bk) are displayed. It differs in the point to form. The process cartridges 7a, 7b, 7c, and 7d are arranged in this order from the bottom to the top. In the following description, the process cartridges 7a, 7b, 7c, and 7d are referred to as process cartridges 7 when it is not particularly necessary to distinguish colors. The same applies to other members.

  The process cartridges 7a, 7b, 7c, 7d are constituted by drum units 5a, 5b, 5c, 5d and developing units 4a, 4b, 4c, 4d. Among these, the former drum units 5a, 5b, 5c, and 5d include photosensitive drums 1a, 1b, 1c, and 1d that are image carriers, charging rollers 2a, 2b, 2c, and 2d, a cleaner, and a toner container. Have.

  The latter developing units 4a, 4b, 4c, and 4d include developing rollers 40a, 40b, 40c, and 40d, toner charging rollers 61a, 61b, 61c, and 61d, a developer applying roller, and a developer applying blade. is doing.

  The scanner units 3a, 3b, 3c, and 3d are arranged in the vertical direction and substantially in the horizontal direction of the photosensitive drums 1a, 1b, 1c, and 1d, similarly to the process cartridges 7a, 7b, 7c, and 7d. The image light corresponding to the image signal from the scanner unit selectively exposes the surfaces of the charged photosensitive drums 1a, 1b, 1c, and 1d to form an electrostatic latent image. .

  In the right side of the image forming apparatus in the figure, an electrostatic conveyance belt 12 that is stretched over four rollers, that is, an adsorption facing roller 21, an electrostatic transfer conveyance belt drive roller 22, and tension rollers 23 and 24, is disposed. Has been. The electrostatic conveyance belt 12 is disposed so as to circulate and move so as to face the photosensitive drums 1a, 1b, 1c, and 1d. The electrostatic transfer / conveying belt 12 is made of a resin material such as PVdF (polyvinylidene fluoride), polyamide, polyimide, PET (polyethylene terephthalate), and polycarbonate having a thickness of 50 to 300 μm and a volume resistivity of about 109 to 1016 Ω · cm. Also, rubber such as chloroprene rubber, EPDM (ethylene-propylene-diene terpolymer), NBR (nitrile butadiene rubber), urethane rubber, etc. having a thickness of 0.5-2 mm and volume resistivity of 109-1016 Ω · cm Material is used. Further, if necessary, conductive fillers such as carbon, ZnO, SnO2, and TiO2 may be dispersed in these materials to adjust the volume resistivity to about 107 to 1011 Ω · cm.

  The electrostatic transfer / conveying belt 12 electrostatically attracts the transfer material P to the outer peripheral surface of the portion located on the left side in the drawing so that the transfer material P is brought into contact with the photosensitive drums 1a, 1b, 1c, and 1d. It moves cyclically. As a result, the transfer material P is transported to the transfer position by the electrostatic transfer transport belt 12, and the toner images on the photosensitive drums 1a, 1b, 1c, and 1d are respectively transferred.

  The transfer rollers 6a, 6b, 6c, and 6d are arranged in parallel at positions that are in contact with the inside of the electrostatic transfer / conveying belt 12 and face the four photosensitive drums 1a, 1b, 1c, and 1d.

  The transfer rollers 6a, 6b, 6c, and 6d electrostatically transfer the toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d onto the transfer material P carried on the electrostatic transfer conveyance belt 12. To do. As the transfer roller, for example, a metal core bar covered with an elastic body such as EPDM, urethane rubber, NBR or the like adjusted to a volume resistivity of about 105 to 108 Ω · cm can be used. A positive transfer bias is applied to the transfer rollers 6a, 6b, 6c, and 6d from a transfer bias application power source (not shown). Due to the electric field due to the transfer bias, the negative toner images on the photosensitive drums 1a, 1b, 1c, and 1d are sequentially transferred onto the transfer material P in contact with the photosensitive drums 1a, 1b, 1c, and 1d.

  The feeding / conveying device 17 feeds and conveys the transfer material P to the image forming unit, and a plurality of transfer materials P are stored in the paper feeding cassette 11. At the time of image formation, the paper feed roller 9 (half-moon roller) is driven and rotated in accordance with the image forming operation to separate and feed the transfer material P in the paper feed cassette 11 one by one. The transferred transfer material P is temporarily stopped when its leading end abuts against the registration roller pair 10, forms a loop, and is conveyed to a nip formed by the suction roller 18 and the roller 21.

  A registration sensor 16 is disposed immediately downstream of the registration roller pair 10. Image formation is performed on the basis of the time when the transfer material P crosses here. The attracting roller 18 electrostatically attracts the transfer material P conveyed from the feeding / conveying device 17 to the surface of the transfer belt 12. As a suction roller, for example, a metal core is covered with a conductive elastic material adjusted to a volume resistivity of about 101 to 109 Ω · cm, and a thickness of about 5 to 500 μm adjusted to a volume resistivity of about 104 to 1010 Ω · cm. A conductive film layer of a certain degree is provided.

  As the conductive elastic material, a non-foamed or foamable conductive rubber composition containing a conductive agent can be used. Specific examples thereof include rubbers such as butadiene, isoprene, chloroprene, styrene butadiene, ethylene propylene, polynorbornene, polyurethane, and silicone. Moreover, as a conductive agent to be blended in these rubber compositions, carbon black, graphite, metal, various metal oxides, ionic substances, electromigration complexes, and the like can be used.

  For example, the following is used for the conductive film layer. Nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, urethane resin, urea resin and carbon black, graphite, tin oxide, titanium oxide and other metal oxides, ionic substances, charge transfer complexes and other conductive agents Are mixed.

  The suction roller 18 is pressure-bonded to the roller 21 via the electrostatic transfer conveyance belt 12 by spring-pressing the core metal portions at both ends with a wire thickness of about 0.04 to 0.5 N (Newton) (not shown), The transfer belt 12 is driven to rotate. As a result, the transfer material P is electrostatically attracted onto the electrostatic transfer conveyance belt 12 and fed to the nip formed by the transfer rollers 6a, 6b, 6c, 6d and the photosensitive drums 1a, 1b, 1c, 1d. It will be done.

  The fixing device 14 is a heating and pressure fixing device, and fixes the toner image transferred to the transfer material P. The fixing device 14 includes a cylindrical fixing film 140 as a rotating body having a heat generating layer (conductive magnetic member), and a pressure roller 143 that presses against the fixing film 140 and applies heat and pressure to the transfer material P. Yes. That is, the transfer material P onto which the toner image on the photosensitive drum 1 has been transferred is conveyed by the fixing film 140 and the pressure roller 143 when passing through the fixing device 14 and is given heat and pressure. As a result, the toner image is fixed on the surface of the transfer material P. The fixed transfer material P is discharged by the paper discharge roller pair 15 onto the paper discharge tray 20 on the upper surface of the image forming apparatus main body A with the image surface facing down.

[Phase control operation]
As shown in FIGS. 2 and 3, a shaft portion 32a that rotates integrally with a gear 118 for driving the photosensitive drums 1a to 1d is provided inside the driving means. A coupling portion 33 that rotates integrally with the shaft portion 32a and transmits a rotational driving force to the process cartridge 7 is integrally configured. A positioning hole 34 is formed from the coupling portion 33 to the shaft portion 32a to fit and determine the position of the drum shaft 111a concentrically fixed with the photosensitive drum 1. This integral component can be a resin molded product.

  As shown in FIGS. 2 and 3, the shaft portion 32a is supported by the cylinder bearing portion 35 installed on the apparatus main body A side so that only the shaft portion 32a in the vicinity of the gear root is rotationally linearly movable with the required accuracy. Yes. The peripheral portion of the coupling portion 33 is wide enough not to conflict with the shaft position determined by fitting the positioning hole 34 to the drum shaft 111a and does not interfere with the coupling portion 33. A clearance that can be supported is provided.

  The gear shaft (shaft portion 32a) is inclined due to the positional accuracy between the cylinder bearing portion 35 and the drum shaft 111a, but the distance from the gear 118 side end of the shaft portion 32a to the positioning hole 34 is set sufficiently long, Defects such as inclination of the gear shaft (shaft portion 32a) are prevented from occurring.

  The component integrated with the gear 118 is movable in the axial direction and is pressed by the leaf spring 37 in the direction of the photosensitive drum 1 (rightward in FIG. 3).

  A drum shaft 111a that rotates integrally with the photosensitive drum 1 is fixed to the photosensitive drum 1 using a fixing pin (not shown), and the drum shaft 111a is accurately positioned on the apparatus main body 100a via a bearing 38. ing.

  A non-driving side (driven side) coupling 36 is fixed to the end of the drum shaft 111a via a fixing pin 111b. The non-driving side coupling 36 is connected to the driving side (main driving side) coupling 33. Engagement and rotational driving force are transmitted.

  As shown in FIGS. 2 and 3, the driving side coupling 33 and the non-driving side coupling 36 are triangular spiral couplings that are configured to always engage with each other when driven in a predetermined direction. .

  As shown in FIG. 4, each of the photosensitive drums 1a, 1b, 1c, 1d “hereinafter simply referred to as (photosensitive drum 1)” is dedicated to the motors 41a, 41b, 41c, 41d “hereinafter simply referred to as“ motors ”. 41) ”is provided. A gear 39 fixed to the drive shaft of the motor 41 is engaged with a gear 118 fixed to the drum shaft 111a. Then, the photosensitive drum 1 is driven by the motor 41 through the gears 39 and 118.

  The teeth 31 of the gear 118 shown in FIGS. 2 and 3 are provided with targets 42a, 42b, 42c, and 42d “hereinafter simply referred to as the target 42” for detecting the phase as shown in FIG. It is. The target 42 can be detected once per revolution by optical or magnetic phase detectors 43a, 43b, 43c, 43d “hereinafter referred to as a unit (phase detector 43)”. it can.

  In FIG. 4, 51 is an axial phase detection unit that detects the axial phase of the photosensitive drum 1, 52 is a speed variation detection unit that detects speed variation of the photosensitive drum 1, and 53 is an axial phase detection unit 51 and a speed variation detection unit. It is a calculating part which calculates based on the detected value of 52. Reference numeral 54 denotes a motor control unit (control means) that controls the motor 41 based on the calculation value of the calculation unit 53.

  As shown in FIG. 4, an image detection sensor 44 is provided so as to face the electrostatic transfer conveyance belt 12, and the image on the transfer material conveyance belt 12 is optically detected by the image detection sensor 44. be able to.

  In the image forming apparatus according to the present embodiment, the main component of the angular velocity unevenness is only one rotation cycle of the photosensitive drum 1. Therefore, when patterns formed on the photosensitive drum 1 at regular time intervals are transferred to the electrostatic transfer / conveying belt 12 and read by the image detection sensor 44, the accumulated variation component of the pattern intervals is obtained. A sine waveform as shown in FIG.

  In FIG. 5, the horizontal axis represents the distance from the front end of the image, and the vertical axis represents the amount of displacement.

  In order to obtain the phase relationship between the four colors, the image formation start timing of each color is managed, image formation is performed for each color, a pattern is detected, a sine waveform as shown in FIG. 5 is obtained, and the image formation start timing interval is determined. Processing such as correction and comparison may be performed.

  Further, as shown in FIG. 5, when the Bk (black) color is used as a reference, the color shift relative to the Bk color can be reduced by shifting the Y (yellow) color by the distance y to the image leading end side. it can. Similarly, the M (magenta) color may be shifted to the image leading end side by a distance m, and the C (cyan) color may be shifted to the image leading end side by a distance c.

  However, since this phase detection requires a predetermined time, if phase detection is frequently performed, a loss of image formation time occurs.

  Therefore, normally, control is performed based on phase information from the phase detector 43 that detects the phase of the gear 118 that rotates the photosensitive drum 1.

  If the phase waveform detected by the phase detector 43 is in a state as shown in FIG. 6, if the phase of the Y-color gear 18 is controlled so as to turn faster by the time y ′ corresponding to the distance y in FIG. The relative color shift between the Bk color and the Y color decreases. Similarly, the phase of the M-color gear 18 may be controlled so as to be rotated earlier by a time m ′ corresponding to the distance m, and the phase of the C-color gear 18 may be rotated earlier by a time c ′ corresponding to the distance c. Just control.

  This phase control can be performed by adjusting the speed of the motor 41 by the motor control unit 54.

  When such phase control is performed and the above-described phase relationship is obtained, the state shown in FIG. 7 is obtained, and the relative color shift can be reduced to about ½ or less of the conventional one.

  A misregistration detection pattern as shown in FIG. 8 is transferred to the electrostatic transfer conveyance belt 12, and this pattern is read by image detection sensors 44 (see FIG. 4) provided on both sides of the electrostatic transfer conveyance belt 12. The amount of misregistration of each color is detected.

  In FIG. 8, the reference color a (hereinafter Bk: black) is shown on one side, and the detection color b (hereinafter Y: yellow, M: magenta, C: cyan) is shown on the other side. In FIG. 8, a1 to a19 and b1 to b19 indicate detection timings of the respective misregistration detection patterns, and arrows indicate the transport direction of the electrostatic transfer transport belt 12.

  In the misregistration detection pattern, since the reference color and the detection color are arranged at the same position with respect to the paper conveyance direction, it is difficult to be affected by the driving irregularity (speed irregularity) caused by the electrostatic transfer conveyance belt 12. .

  As shown in FIG. 9, the positional deviation detection pattern can be canceled by setting the pitch of the misregistration detection pattern to an integral multiple of the driving unevenness other than the photosensitive drum 1.

  The rotation phase of the reference color is fixed, and the rotation phase of the detected color with respect to the reference color is detected by being shifted by a predetermined angle. By repeating the above detection process, the relationship between the rotation phase and the amplitude of the detected color with respect to the reference color can be obtained as shown in FIG. 10, and the optimum phase of each color can be easily determined. It can be done.

  In FIG. 10, the vertical axis represents the amplitude of the amount of positional deviation of the detected color with respect to the reference color, and the horizontal axis represents the rotational phase of the detected color with respect to the reference color.

The amplitude of the positional deviation amount of the photosensitive drum 1 of the detected color with respect to the reference color of the positional deviation detection pattern is expressed by the following formulas 1-3.
ΔC1 (θ) = MAX (a1-bc1, a2-bc2,... A18-bc18, a19-bc19) -MIN (a1-bc1, a2-bc2,... A18-bc18 , A19-bc19) / 2 (1)
.DELTA.Y1 (.theta.) = MAX (a1-by1, a2-by2,... A18-by18, a19-by19) -MIN (a1-by1, a2-by2,... A18-by18 , A19-by19) / 2 (2)
ΔM1 (θ) = MAX (a1-bm1, a2-bm2,... A18-bm18, a19-bm19) -MIN (a1-bm1, a2-bm2,... A18-bm18 , A19-bm19) / 2 (3)
Further, there is a method of shortening the time by roughly adjusting the rotational phase of the photosensitive drum 1 of the detected color with respect to the reference color and then finely adjusting the rotational phase.

  In the present embodiment, first, a displacement detection pattern is detected at intervals of 120 ° with respect to the reference phase. Using the detection result, an angle between the phase angles having a small amplitude of the positional deviation amount is detected. Further, by using the detection result, the phase angle between the small amplitudes of the positional deviation amount is measured, and the angle at which the amplitude of the positional deviation amount is finally minimized is set as the optimum phase.

  By feeding back the phase detection result to the rotational phase control of the motor 41, color misregistration can be reduced.

  An example of the processing operation of the detecting means for detecting the angle between the phase angles having a small amplitude of the positional deviation amount while sequentially changing the phase of the photosensitive drum 1 as described above will be described with reference to FIGS. To do.

  When detecting the amplitude of the positional deviation amount at each phase of the photosensitive drum 1, first, the amplitude of the positional deviation amount with respect to three phases of 0 °, 120 °, and 240 ° is measured (FIG. 11). Step S1100).

  If it is detected as a measurement result in step S1100 of FIG. 11 that the amplitude of the positional deviation amount is maximum when the phase is controlled at 0 °, the process proceeds to step S1101. In step S1101, the phase is controlled to 180 °, which is an intermediate between 120 ° and 240 °. Then, the amplitude of the positional deviation amount is measured again in the 180 ° phase.

  Note that the maximum amplitude of the positional deviation amount means that the speed unevenness is the smallest.

  After the measurement in step S1101 in FIG. 11, the measurement result in the 120 ° phase has the maximum amplitude of the positional deviation amount based on the measurement result in the case of controlling at each phase of 120 °, 180 °, and 240 °. If detected, the process proceeds to step S1102. In step S1102, the amplitude of the positional deviation amount with respect to the 210 ° phase is measured.

  Next, in step S1103, the phase having the smallest positional deviation amount amplitude is determined from 180 °, 210 °, and 240 °, and then this processing operation ends.

  Further, after the measurement with respect to the 180 ° phase in step S1101 in FIG. 11 is completed, the measurement result in the case of controlling with each phase of 120 °, 180 ° and 240 ° is confirmed. If the measurement result with respect to the 240 ° phase detects that the amplitude of the positional deviation amount is the maximum, the process proceeds to step S1104. In step S1104, the amplitude of the positional deviation amount with respect to the 150 ° phase is measured. Next, in step S1105, a phase with the smallest positional deviation amount amplitude is determined from 120 °, 150 °, and 180 °, and then this processing operation ends.

  Further, as a measurement result for the phases of 0 °, 120 °, and 240 ° in step S1100 in FIG. 11, when the measurement result for the 120 ° phase detects that the speed unevenness is the smallest (maximum displacement error amplitude). The process proceeds to step S1106. In step S1106, the amplitude of the positional deviation amount with respect to the 300 ° phase is measured.

  After the measurement with respect to the 300 ° phase in step S1106 in FIG. 11 is completed, the amplitude measurement result of the positional deviation amount when the control is performed with each phase of 0 °, 240 °, and 300 ° is confirmed. As a measurement result, when it is detected that the measurement result with respect to the 0 ° phase has the smallest speed unevenness (maximum positional deviation amount amplitude), the process proceeds to step S1107. In step S1107, the amplitude of the positional deviation amount with respect to the 270 ° phase is measured. Next, in step S1108, a phase with the smallest positional deviation amount amplitude is determined from 240 °, 270 °, and 300 °, and then this processing operation ends.

  After the measurement with respect to the 300 ° phase in step S1106 in FIG. 11 is completed, the amplitude measurement result of the positional deviation amount when the control is performed with each phase of 0 °, 240 °, and 300 ° is confirmed. As a measurement result, when the measurement result for the 240 ° phase detects that the speed unevenness is the smallest (maximum positional deviation amount amplitude), the process proceeds to step S1109. In step S1109, the amplitude of the positional deviation amount with respect to the 330 ° phase is measured. Next, in step S1110, a phase with the smallest positional deviation amount amplitude is determined from 300 °, 330 °, and 0 °, and then this processing operation ends.

  Further, in step S1100 in FIG. 11, the measurement results for the phases of 0 °, 120 °, and 240 ° are confirmed. As a measurement result, when the measurement result for the 240 ° phase detects that the speed unevenness is the smallest (maximum displacement error amplitude), the process proceeds to step S1111 in FIG. In step 1111, the amplitude of the positional deviation amount with respect to the 60 ° phase is measured.

  In addition, after the measurement for the 60 ° phase in step S1111 in FIG. 12 is completed, the amplitude measurement result of the positional deviation amount when the control is performed with each phase of 0 °, 60 °, and 120 ° is confirmed. As a measurement result, when it is detected that the measurement result with respect to the 120 ° phase has the smallest speed unevenness (maximum positional deviation amount amplitude), the process proceeds to step S1112. In step S1112, the amplitude of the positional deviation amount with respect to the 30 ° phase is measured. Next, in step S1113, the phase with the smallest positional deviation amount amplitude is determined from 0 °, 30 °, and 60 °, and then this processing operation ends.

  In addition, after the measurement for the 60 ° phase in step S1111 in FIG. 12 is completed, the amplitude measurement result of the positional deviation amount when the control is performed with each phase of 0 °, 60 °, and 120 ° is confirmed. As a measurement result, when it is detected that the measurement result with respect to the 0 ° phase has the smallest speed unevenness (maximum positional deviation amount amplitude), the process proceeds to step S1114. In step S1114, the amplitude of the positional deviation amount with respect to the 90 ° phase is measured. Next, in step S1115, the phase with the smallest positional deviation amount amplitude is determined from 60 °, 90 °, and 120 °, and then this processing operation ends.

  The phase with the smallest amplitude of the displacement amount determined in S1103, S1105, S1108, S1110 in FIG. 11 and S1113 and S1115 in FIG. 12 is notified to the motor control unit 54 in FIG. 5 as the optimum phase of the photosensitive drum 1. Is done. Then, the motor controller 54 notified of the amplitude measurement result of the positional deviation amount adjusts the phase by controlling the speed of the motors 41a to 41d in order to adjust the phase of the photosensitive drum 1 according to the measurement result. . The electrostatic transfer transport belt 12 is driven at a constant speed, and the speed is made uniform in a state where the speed is not affected by the changing peripheral speed of the photosensitive drum 1.

  Next, the control of an electrostatic transfer conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  A solid line (a) in FIG. 13 indicates the peripheral speed of the photosensitive drum 1 including during phase adjustment, and a broken line (b) in FIG. 13 indicates the peripheral speed of the electrostatic transfer conveyance belt 22 to the photosensitive drum 1. Show. As shown in FIG. 13, the photosensitive drum 1 performs phase adjustment after a phase detection period after the motor is started. The speed during phase adjustment at this time varies depending on the phase difference detected in the phase detection period, but the speed of the phase difference of 180 ° is the largest from the detection result as shown in the above-described arithmetic expression. In the embodiment of the present invention, the upper limit is a peripheral speed difference of ± 3%. At this time, (b) in FIG. 13 shows that the circumferential speed of the electrostatic transfer conveyor belt 22 is different from that of the photosensitive drum by a circumferential speed of 105% before the start of phase detection. Driven. This is an operation for eliminating the speed fluctuation element of the electrostatic transfer conveyance belt at the time of phase detection of the photosensitive drum 1, and is set not to change during phase detection and phase control. The value of 105% is a peripheral speed difference at which the speed of the electrostatic transfer conveyance belt 12 does not fluctuate even with respect to the speed fluctuation of the photosensitive drum 1 that occurs during the phase adjustment period.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the control of this embodiment, the conveyance rotation is performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of production due to the speed fluctuation during the phase control of the photosensitive drum 1. Control becomes possible.

  In addition, since the electrostatic transfer / conveying belt 12 having a stable frictional force can be stably rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect. .

  In the present embodiment, when an example of the present invention is described with reference to FIG. 13, the range of the peripheral speed difference is described. However, in practice, in various configurations of the present invention, there are better combinations depending on various conditions, so it goes without saying that the present invention is not limited to the conditions and ranges described above.

  The subsequent operation sequence related to image formation is formed using the process unit as described above, but since it is a well-known technique, its description is omitted here.

  Next, Embodiment 2 of the present invention will be described with reference to FIG.

  Since the phase control operation is the same as that of the first embodiment, description thereof is omitted.

  Next, control of an electrostatic transfer conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  A solid line (a) in FIG. 14 indicates the peripheral speed of the photosensitive drum 1 including during phase adjustment, and a broken line (b) in FIG. 14 indicates the peripheral speed of the electrostatic transfer conveyance belt 22 to the photosensitive drum 1. Show. As shown in FIG. 14, the photosensitive drum 1 performs phase adjustment after a phase detection period after the motor is started. The speed during phase adjustment at this time varies depending on the phase difference detected in the phase detection period, but the speed of the phase difference of 180 ° is the largest from the detection result as shown in the above-described arithmetic expression. In the embodiment of the present invention, the control speed range is set as a peripheral speed difference of ± 3%. At this time, (b) in FIG. 14 shows that the circumferential speed of the electrostatic transfer conveyance belt 22 is driven with a circumferential speed difference of 95% with respect to the photosensitive drum before the phase detection is started. . This is to eliminate the speed fluctuation element of the electrostatic transfer conveyance belt when the phase of the photosensitive drum 1 is detected, and is not changed during phase detection and phase control.

  Therefore, the peripheral speed difference is set as the peripheral speed at which the speed of the electrostatic transfer conveyance belt 12 does not change even with respect to the speed fluctuation of the photosensitive drum 1 that occurs during the phase adjustment period.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the present embodiment, the conveyance rotation control can be performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of manufacture due to the speed fluctuation during the phase control of the photosensitive drum 1. It becomes possible.

  In addition, since the electrostatic transfer / conveying belt 12 having a stable frictional force can be stably rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect. .

  In addition, when describing an example of the present invention with reference to FIG. 14, the range of the peripheral speed difference is described. However, in practice, there are better combinations depending on various conditions in various configurations of the present invention, and it goes without saying that the present invention is not limited to the conditions and ranges described above.

  The subsequent operation sequence related to image formation is formed using the process unit as described above, but since it is a well-known technique, its description is omitted here.

  Next, the operation of the third embodiment of the present invention will be described with reference to FIG.

  Since the phase control operation is the same as that of the first embodiment, description thereof is omitted.

  Next, the control of an electrostatic transfer / conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer / conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  Solid lines (a), (a) ′, and (a) ″ in FIG. 15 indicate peripheral speeds of the plurality of photosensitive drums 1a to 1c including during phase adjustment, and a broken line (b) in FIG. 15 shows the peripheral speed of the transfer / conveying belt 22 to the photosensitive drum 1. As shown in Fig. 15, the photosensitive drum 1 performs phase adjustment through a phase detection period after the motor is started. The speed of the phase difference varies depending on the phase difference detected in the phase detection period, but as shown in the above calculation formula, the phase difference of 180 ° is the largest from the detection result. 15 (b), at this time, (b) in FIG. 15 shows that the peripheral speed of the electrostatic transfer conveyance belt 22 is not detected until the phase detection starts. Considering the upper limit speed + 3% during phase adjustment and driving with a peripheral speed difference of 105% This is to even eliminate the speed fluctuation element of the electrostatic transfer conveyance belt when the phase of the photosensitive drum 1 is detected, and is not changed during phase detection and phase control.

  Therefore, the peripheral speed difference is set as the peripheral speed at which the speed of the electrostatic transfer conveyance belt 12 does not change even with respect to the speed fluctuation of the photosensitive drum 1 that occurs during the phase adjustment period.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the present embodiment, the conveyance rotation control can be performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of manufacture due to the speed fluctuation during the phase control of the photosensitive drum 1. It becomes possible.

  Further, since the electrostatic transfer / conveying belt 12 having a stable frictional force can be stably rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect.

  In addition, when describing an example of the present invention with reference to FIG. 15, the range of the peripheral speed difference is described. However, in practice, there are better combinations depending on various conditions in various configurations of the present invention, and it goes without saying that the present invention is not limited to the conditions or ranges described above.

  The subsequent operation sequence related to image formation is formed using the process unit as described above, but since it is a well-known technique, its description is omitted here.

  Next, the operation of Embodiment 4 of the present invention will be described with reference to FIG.

  Since the phase control operation is the same as that of the first embodiment, description thereof is omitted.

  Next, the control of an electrostatic transfer conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  Solid lines (a), (a) ′, and (a) ″ in FIG. 16 indicate peripheral speeds of the plurality of photosensitive drums 1a to 1c including during phase adjustment, and a broken line (b) in FIG. 16 shows the peripheral speed of the transfer / conveying belt 22 to the photosensitive drum 1. As shown in Fig. 16, the photosensitive drum 1 performs phase adjustment through a phase detection period after the motor is started. The speed of the phase difference varies depending on the phase difference detected in the phase detection period, but as shown in the above calculation formula, the phase difference of 180 ° is the largest from the detection result. 16, the range of the peripheral speed is ± 3%, and at this time, (b) in FIG. Driven with a peripheral speed difference of 95% in consideration of the upper limit speed -3% during phase adjustment This is to even eliminate the speed fluctuation element of the electrostatic transfer conveyance belt when the phase of the photosensitive drum 1 is detected, and is not changed during phase detection and phase control.

  Therefore, the peripheral speed difference is set as the peripheral speed at which the speed of the electrostatic transfer conveyance belt 12 does not change even with respect to the speed fluctuation of the photosensitive drum 1 that occurs during the phase adjustment period.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the present embodiment, the conveyance rotation control can be performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of manufacture due to the speed fluctuation during the phase control of the photosensitive drum 1. It becomes possible.

  In addition, since the electrostatic transfer / conveying belt 12 having a stable frictional force can be stably rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect. .

  In addition, when describing an example of the present invention with reference to FIG. 16, the range of the peripheral speed difference is described. However, in practice, there are better combinations depending on various conditions in various configurations of the present invention, and it goes without saying that the present invention is not limited to the conditions or ranges described above.

  The subsequent operation sequence related to image formation is formed using the process unit as described above, but since it is a well-known technique, its description is omitted here.

  Next, the operation of the fifth embodiment of the present invention will be described with reference to FIG.

  Since the phase control operation is the same as that of the first embodiment, description thereof is omitted.

  Next, the control of an electrostatic transfer conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  Solid lines (a), (a) ′, and (a) ″ in FIG. 17 indicate peripheral speeds of the plurality of photosensitive drums 1a to 1c including during phase adjustment, and a broken line (b) in FIG. 17 shows the peripheral speed of the transfer / conveying belt 22 to the photosensitive drum 1. As shown in Fig. 17, the photosensitive drum 1 performs phase adjustment through a phase detection period after the motor is started. The speed of the phase difference varies depending on the phase difference detected in the phase detection period, but as shown in the above calculation formula, the speed of the phase difference of 180 ° is the largest from the detection result. 17 (b), the circumferential speed of the electrostatic transfer conveyance belt 22 is being adjusted in phase with respect to the photosensitive drum in the embodiment of the present invention before phase detection is started. Considering the upper limit speed of + 3% and driving with a peripheral speed difference of 105% This is to eliminate the speed fluctuation element of the electrostatic transfer conveyance belt when detecting the phase of the photosensitive drum 1, and the phase detection is not changed, and the target peripheral speed 100 after a desired time during the phase control. In this control, the electrostatic transfer and conveyance belt is controlled by always maintaining a constant peripheral speed difference even when the speed of the photosensitive drum 1 changes during the phase adjustment period. A peripheral speed difference is set as a peripheral speed at which the speed of 12 is not affected by the photosensitive drum 1.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the present embodiment, the conveyance rotation control can be performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of manufacture due to the speed fluctuation during the phase control of the photosensitive drum 1. It becomes possible.

  In addition, since the electrostatic transfer / conveying belt 12 having a stable frictional force can be stably rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect. .

  In addition, when describing an example of the present invention with reference to FIG. 17, the range of the peripheral speed difference is described. However, in practice, there are better combinations depending on various conditions in various configurations of the present invention, and it goes without saying that the present invention is not limited to the conditions or ranges described above.

  The subsequent operation sequence related to image formation is formed using the process unit as described above, but since it is a well-known technique, its description is omitted here.

  Next, the operation of the fifth embodiment of the present invention will be described with reference to FIG.

  Since the phase control operation is the same as that of the first embodiment, description thereof is omitted.

  Next, control of an electrostatic transfer conveyance belt drive motor 22 ′ (not shown) that drives the electrostatic transfer conveyance belt drive roller 22 corresponding to the speed change of the photosensitive drum 1 during phase adjustment will be described with reference to FIG. .

  Solid lines (a), (a) ′, (a) ″ in FIG. 18 indicate peripheral speeds of the plurality of photosensitive drums 1a to 1c including during phase adjustment, and a broken line (b) in FIG. 18 shows the peripheral speed of the transfer / conveying belt 22 to the photosensitive drum 1. As shown in Fig. 18, the photosensitive drum 1 performs phase adjustment through a phase detection period after motor activation. The speed of the phase difference varies depending on the phase difference detected in the phase detection period, but as shown in the above calculation formula, the speed of the phase difference of 180 ° is the largest from the detection result. 18B, at (b) in FIG. 18, the circumferential speed of the electrostatic transfer conveyance belt 22 is being adjusted in phase with respect to the photosensitive drum in the embodiment of the present invention before the start of phase detection. In consideration of an upper limit speed of −3%, driving is performed with a peripheral speed difference of 95%. This is to eliminate the speed fluctuation element of the electrostatic transfer conveyance belt at the time of detecting the phase of the photosensitive drum 1, and does not change the phase detection, and the target peripheral speed is 100% after a desired time during the phase control. The electrostatic transfer conveyance belt 12 is controlled so as to always maintain a constant difference in peripheral speed even with respect to the speed fluctuation of the photosensitive drum 1 occurring during the phase adjustment period. The peripheral speed difference is set as a peripheral speed that is not affected by the photosensitive drum 1.

  The above is an example of the speed control from the start of the driving motor for the electrostatic transfer conveyance belt 12 to the end of the phase control in the present invention.

  By carrying out the present embodiment, the conveyance rotation control can be performed at a desired speed without being controlled by the difference in behavior due to the frictional force of the electrostatic transfer conveyance belt 12 at the initial stage of manufacture due to the speed fluctuation during the phase control of the photosensitive drum 1. It becomes possible.

  Further, since the electrostatic transfer / conveying belt 12 having a stable frictional force can always be rotated by the driving force of the driving motor of the electrostatic transfer / conveying belt 12, this speed control has no adverse effect.

  In addition, when describing an example of the present invention with reference to FIG. 18, the range of the peripheral speed difference is described. However, in practice, there are better combinations depending on various conditions in various configurations of the present invention, and it goes without saying that the present invention is not limited to the conditions or ranges described above.

  The subsequent operation sequence related to image formation is formed through the process unit as described above, but since it is a well-known technique, its description is omitted here.

(Other examples)
In the above-described embodiment, even when the intermediate transfer member that carries the image is used as the transport unit that is transported along the transfer unit 6, the control described in the first to sixth examples is equivalent. The effect of can be obtained.

  In the configuration of FIG. 1, 12 is not a transfer conveyance belt, but is an intermediate transfer belt, for example. In that case, the image formed on the photosensitive drum is superimposed and transferred onto the intermediate transfer member, and the image is transferred from the intermediate transfer member to the transfer material in a lump.

1 is an overall cross-sectional view illustrating a contact state of an image forming apparatus used in the present invention. FIG. 2 is a perspective view illustrating a configuration of a main part of a drive unit / drive transmission unit of a photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a main configuration of a drive unit / drive transmission unit of a photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a configuration of a main part of a driving unit of a photosensitive drum and a control system in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a state of color misregistration of each color before control in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a state of a signal obtained by detecting a phase of a gear that rotationally drives a photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a state in which color misregistration of each color after phase control of the photosensitive drum is eliminated in the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating a misregistration detection pattern and an example of its arrangement in the image forming apparatus according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating a positional deviation amount with respect to a reference color when driving unevenness other than the photosensitive drum is canceled in the image forming apparatus according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating a change in displacement amplitude when the rotational phase of the photosensitive drum is changed in the image forming apparatus according to the first embodiment of the present invention. 3 is a flowchart showing a flow of an optimum phase detection processing operation of the photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. 3 is a flowchart showing a flow of an optimum phase detection processing operation of the photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating a peripheral speed and a peripheral speed of an electrostatic transfer conveyance belt when an optimum phase detection process is performed on the photosensitive drum in the image forming apparatus according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating a peripheral speed and a peripheral speed of an electrostatic transfer conveyance belt when an optimum phase detection process is performed on a photosensitive drum in an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a diagram illustrating a peripheral speed and a peripheral speed of an electrostatic transfer conveyance belt when an optimum phase detection process is performed on a photosensitive drum in an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a diagram illustrating a peripheral speed and a peripheral speed of an electrostatic transfer conveyance belt when an optimum phase detection process is performed on a photosensitive drum in an image forming apparatus according to a fourth embodiment of the present invention. It is a figure which shows the peripheral speed at the time of the optimal phase detection process operation | movement of the photosensitive drum in the image forming apparatus which concerns on 5th embodiment of this invention, and the peripheral speed of an electrostatic transfer conveyance belt. It is a figure which shows the peripheral speed at the time of the optimal phase detection processing operation | movement of the photoconductive drum in the image forming apparatus which concerns on 6th embodiment of this invention, and the peripheral speed of an electrostatic transfer conveyance belt. It is a whole sectional view of an image forming device showing conventional technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a-d Photosensitive drum 6a-d Transfer means 12 Electrostatic transfer conveyance belt 40a-d Developing roller 7a-d Process cartridge 5a-d Drum unit 61a-d Toner charging roller 3a-d Scanner unit 118 Gear 111a Drum shaft 111b Fixed pin 32a Shaft portion 33 Coupling 34 Positioning hole 35 Cylinder bearing portion 36 Coupling 37 Leaf spring 38 Bearing 39 Gear 41 Motor 42 Target 43 Phase detection device 44 Image detection sensor 51 Shaft phase detection portion 52 Speed unevenness detection portion 53 Calculation portion 54 Motor Control unit (control means)

Claims (11)

An image forming apparatus comprising: a plurality of image carriers; and transfer conveying means for transferring an image formed on the plurality of image carriers to a transfer material,
Phase adjusting means for adjusting the rotational phase of the plurality of image carriers;
A speed control means for controlling the transfer conveying means to rotate at a speed different from the rotational speed of the plurality of image carriers during the phase adjustment of the plurality of image carriers by the phase adjusting means;
An image forming apparatus comprising: An image forming apparatus comprising: a plurality of image carriers; and an intermediate transfer unit for supporting images formed on the plurality of image carriers.
Phase adjusting means for adjusting the rotational phase of the plurality of image carriers;
A speed control means for controlling the intermediate transfer means to rotationally drive at a speed different from the rotational speed of the plurality of image carriers during the rotational phase adjustment of the plurality of image carriers by the phase adjusting means;
An image forming apparatus comprising:   The rotation speed of the transfer conveying means or the intermediate transfer means is faster than the fastest rotation speed of the image carrier among the plurality of image carriers during the phase adjustment. The image forming apparatus according to 1 or 2.   The rotation speed of the transfer conveying unit or the intermediate transfer unit is slower than the slowest rotation speed of the image carrier among the plurality of image carriers during the phase adjustment. The image forming apparatus according to 1 or 2.   In the phase control period of the image carrier, the speed control unit is configured to transfer the transfer carrier or the intermediate transfer unit faster than the rotation speed of the image carrier that is fastest among the plurality of image carriers in phase adjustment. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled so as to rotate at a constant speed at a high speed.   In the phase control period of the image carrier, the speed control unit is configured such that the transfer conveying unit or the intermediate transfer unit is slower than the rotation speed of the slowest image carrier among the plurality of image carriers during the phase adjustment. The image forming apparatus according to claim 1, wherein the rotation speed is controlled so as to rotate at a constant speed at a low speed.   In the phase control period of the image carrier, the speed control unit is configured to transfer the transfer carrier or the intermediate transfer unit faster than the rotation speed of the image carrier that is fastest among the plurality of image carriers in phase adjustment. The image forming apparatus according to claim 1, wherein the rotation speed of the image forming apparatus is a high speed, and the speed is controlled so as to follow the speed of the image carrier.   In the phase control period of the image carrier, the speed control unit is configured such that the transfer conveying unit or the intermediate transfer unit is slower than the rotation speed of the slowest image carrier among the plurality of image carriers during the phase adjustment. 3. The image forming apparatus according to claim 1, wherein the rotation speed is slow and the speed is controlled so as to follow the speed of the image carrier.   The image forming apparatus according to claim 1, wherein the transfer conveyance unit is a transfer material carrier that carries and conveys the transfer material. A control method for an image forming apparatus, comprising: a plurality of image carriers; and transfer conveying means for transferring images formed on the plurality of image carriers to a transfer material,
A phase adjusting step for adjusting a rotational phase of the plurality of image carriers;
A speed control step for controlling the transfer conveying means to rotate at a speed different from the rotational speed of the plurality of image carriers during the adjustment of the rotational phase of the plurality of image carriers;
A control method for an image forming apparatus, comprising: A control method for an image forming apparatus, comprising: a plurality of image carriers; and an intermediate transfer unit for supporting images formed on the plurality of image carriers.
A phase adjusting step for adjusting a rotational phase of the plurality of image carriers;
A speed control step of controlling the intermediate transfer means to rotate at a speed different from the rotational speed of the plurality of image carriers during adjustment of the rotational phase of the plurality of image carriers;
A control method for an image forming apparatus, comprising:

Images