JP2011033927A - Image forming apparatus and drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce minimally the number of detection sensors for performing phase adjustment caused by rotation unevenness of each image carrier, and to thereby simplify a device constitution and reduce cost, concerning an image forming apparatus for forming a plurality of images by using a plurality of image carriers corresponding to the plurality of images respectively and superposing the plurality of images, and drive devices for driving the image carriers. <P>SOLUTION: The image forming apparatus D and the drive devices 100a, 100b include a first detection sensor 170 constituted so as to detect first detection information of a rotation timing by a first cam part 131 provided on a part in a first peripheral direction α1 of a first rotation member 150, and also to detect second detection information of a rotation timing by a second cam part 141 provided on a part in a second peripheral direction α2 of a second rotation member 160. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a plurality of image carriers and a driving device.

  As the image forming apparatus, a plurality of images (for example, toner images) are formed by an image forming process such as an electrophotographic method using a plurality of image carriers such as a photoreceptor corresponding to the plurality of images, Conventionally, an image forming apparatus that superimposes these images, that is, a so-called tandem type image forming apparatus is known. For example, when forming a full color image, toner images of different colors (usually, yellow (Y), magenta (M), cyan (C), and black (K) color components) are displayed as a plurality of corresponding images. The toner image is formed on the carrier in synchronization with each other, and each toner image is transferred onto a transfer medium such as an intermediate transfer body or a recording material. When the transfer body is an intermediate transfer body, it is further transferred onto the recording material.

  In such a conventional image forming apparatus, a first group image carrier to which at least one of the plurality of image carriers belongs, and a second group image to which at least one of the remaining image carriers belongs. The carrier may be driven independently.

  Specifically, a black image is normally formed independently without forming an image of another color when a monochrome image is formed. In this case, an image carrier corresponding to black and an image forming member (a member including a black developing device) for forming an image on the image carrier are used as other images (yellow, magenta, and cyan images). It is driven by a drive unit such as a motor different from a plurality of corresponding image carriers and an image forming member (a member including yellow, magenta, and cyan developing devices) for forming an image on the image carrier.

  On the other hand, it is necessary to drive an image for images other than black (yellow, magenta, and cyan images). However, in order to reduce the number of drive components and achieve downsizing of the image forming apparatus, yellow that is driven simultaneously. If the magenta and cyan image carriers and the image forming members corresponding to the image carriers are driven by one drive unit, the number of parts can be reduced. Examples of the drive unit that drives the plurality of image carriers and the image forming member include a stepping motor.

  By the way, even if a plurality of images are formed on a plurality of image carriers in synchronization with each other, the images may be shifted when the images of the respective image carriers are superimposed. In order to prevent the occurrence of such image shift, it is important to accurately overlay the images on the image carriers.

  The causes of image misalignment include, for example, the phase of rotation unevenness caused by the eccentricity of the image carrier, the eccentricity of a drive transmission rotary member such as a drive gear that transmits rotational drive from the drive unit to the image carrier, and the like. A deviation can be illustrated.

  For example, when the first group image carrier and the second group image carrier are driven independently, usually, the first group image carrier and the second group image carrier and the second group image carrier are each at the initial drive time such as when the power is turned on or every predetermined period. The rotational phase with the group image carrier is adjusted to a reference rotational phase, which is an optimal rotational phase with as little rotational unevenness as possible. However, even if the phase alignment is performed so that the rotational phase of the first group image carrier and the second group image carrier becomes the reference rotational phase, the first group image carrier and the second group image carrier If only one of them is driven to form an image, the rotational phase of the first group image carrier and the second group image carrier may be completely different from the reference rotational phase. Alternatively, there is a case where the rotational phase of the first group image carrier and the second group image carrier is deviated from the reference rotational phase with the printing operation, resulting in an image shift (phase shift).

  Conventionally, in order to correct the rotational phase of the first group image carrier and the second group image carrier so as to become the reference rotational phase, the rotational phase of a plurality of images to be superimposed (that is, a plurality of image carriers) is conventionally used. A detection sensor for performing phase alignment is provided for each image carrier, the rotation phase is detected by each detection sensor, and the rotation phase difference of the detected rotation phase is detected with respect to the reference rotation phase. By changing at least one of the rotation timing of the first group image carrier and the rotation timing of the second group image carrier to correct the rotation phase of the first group image carrier and the second group image carrier, The phase was adjusted. By doing so, it is possible to reduce the occurrence of rotational misalignment phase shift caused by eccentricity or the like.

  Specifically, a first gear that transmits rotational driving to a first group image carrier (for example, a group carrier to which a black image carrier belongs) and a second group image carrier (for example, yellow, magenta, and cyan). A detection sensor for detecting the rotational phase is provided for each of the second gears that transmit the rotational drive to the group carrier to which the image carrier belongs, and each of the detection sensors allows the first group image carrier and Phase alignment is performed by detecting the rotational phase with the second group image carrier.

  For example, Patent Document 1 below discloses a color image forming apparatus in which a photoconductor is driven by a DC brushless motor with a Hall element via a drum gear provided with a rotational phase detection sensor, and the rotational phase is detected by the drum gear and the motor. Has been.

JP 2006-84669 A

  However, one detection sensor for performing phase alignment due to rotation unevenness of each image carrier is provided for each driven image carrier, for example, a first group image carrier and a second group image carrier independently. In the case of driving, at least two sensors are required, so that the apparatus configuration becomes complicated and the cost is high.

  Therefore, the present invention provides an image forming apparatus that forms a plurality of images using a plurality of image carriers corresponding to the plurality of images, and superimposes the plurality of images, and a driving device that drives the image carrier. An image forming apparatus and a driving apparatus that can reduce the number of detection sensors that perform phase alignment due to uneven rotation of each image carrier as much as possible, thereby simplifying the apparatus configuration and reducing the cost. The issue is to provide.

  In order to solve the above problems, the present invention provides the following image forming apparatus and driving apparatus.

(1) Image forming apparatus An image forming apparatus that forms a plurality of images using a plurality of image carriers corresponding to the plurality of images, and superimposes the plurality of images. A first group image carrier to which at least one image carrier belongs, a second group image carrier to which at least one of the remaining image carriers belongs, and the first group image carrier to be rotated. A first driving unit for rotating the second group image carrier, a first driving unit for rotating the first group image carrier by the first driving unit. First detection information for recognizing the rotation timing of the rotation member, the second rotation member that rotates in accordance with the rotation of the second group image carrier by the second drive unit, and the first group image carrier. Detecting and A single detection sensor for detecting second detection information for recognizing the rotation timing of the two-group image carrier, and on the outer peripheral surface of the first rotation member, at least partially in the rotation axis direction and in the circumferential direction Is provided with a first cam portion (for example, a first cam portion including a first convex portion or a first concave portion), and at least a portion of the outer peripheral surface of the second rotating member in the rotational axis direction. In addition, a second cam portion (for example, a second cam portion including a second convex portion or a second concave portion) is provided in a part of the circumferential direction, and the detection sensor performs the first rotation as the first detection information. Rotation timing detection information by the first cam portion of the member is detected, and rotation timing detection information by the second cam portion of the second rotation member is detected as the second detection information. It is characterized by Image forming apparatus.

(2) Driving device A driving device provided in an image forming apparatus that forms a plurality of images using a plurality of image carriers respectively corresponding to the plurality of images and superimposes the plurality of images, A first driving unit for rotationally driving a first group image carrier to which at least one of the image carriers belongs; and a second group image to which at least one of the remaining image carriers belongs. A second driving unit for rotationally driving the carrier, a first rotating member that rotates as the first group image carrier is rotated by the first driving unit, and the second group by the second driving unit. Detection information of the rotation timing of the first rotation member is detected as first detection information for recognizing the rotation timing of the second rotation member rotating with the rotation of the image carrier and the first group image carrier. ,And And a single detection sensor for detecting detection information of the rotation timing of the second rotation member as second detection information for recognizing the rotation timing of the second group image carrier. On the outer peripheral surface, a first cam portion (for example, a first cam portion including a first convex portion or a first concave portion) is provided in at least part of the rotation axis direction and part of the circumferential direction, and the second On the outer peripheral surface of the rotating member, a second cam portion (for example, a second cam portion including a second convex portion or a second concave portion) is provided on at least a part in the rotational axis direction and a part in the circumferential direction, The detection sensor detects rotation timing detection information by the first cam portion of the first rotation member as the first detection information, and the second cam of the second rotation member as the second detection information. Rotation timing Driving apparatus characterized by being configured to detect the detection information.

  Here, “the rotational phase of the first group image carrier and the second group image carrier” means the relative position between the rotational position of the first group image carrier and the rotational position of the second group image carrier. This is a concept indicating a general positional relationship, and can be expressed by a rotation angle, a time and a distance corresponding to the rotation angle, and the like.

  According to the present invention, the first detection information is detected by the single detection sensor, and the second detection information is detected. As a result, the first group image carrier and the second group image can be obtained with as few sensors as possible to perform phase alignment due to rotational unevenness between the first group image carrier and the second group image carrier. The rotational phase with the carrier can be detected, which makes it possible to simplify the device configuration and reduce the cost.

  Furthermore, the detection configuration of the first detection information and the second detection information can be easily realized by using the detection object by the detection sensor as the first rotation member and the second rotation member.

  In addition, the single detection sensor detects rotation timing detection information by the first cam portion of the first rotation member as the first detection information, and the second rotation member as the second detection information. Since the detection information of the rotation timing by the second cam portion is detected, information on the first rotation angle of the first group image carrier is used as the first detection information of the first rotation member. The second rotation angle of the second group image carrier can be detected as the second detection information of the second rotation member. Thereby, the rotation phase of the first group image carrier and the second group image carrier can be easily detected by the single detection sensor.

  Here, the “rotation angle” refers to an angle formed by a straight line drawn from the rotation center to the position at the start point to be detected and a straight line drawn from the rotation center to the position at the end point to be detected.

  In the present invention, the first rotating member and the second rotating member have rotation axes parallel to each other, and the detection sensor moves along a direction intersecting the rotation axis direction of the first rotating member. A possible first actuator part, a first detected part provided in the first actuator part, a second actuator part movable along a direction intersecting the rotational axis direction of the second rotating member, A second detected part provided in the second actuator part; and a sensor part for detecting the first detected part and the second detected part, wherein the first actuator part includes the first detected part A first facing portion facing the outer peripheral surface of the rotating member is provided, and the second actuator portion is provided with a second facing portion facing the outer peripheral surface of the second rotating member, and the first facing portion. Part and the first cam part The sensor part is formed to detect the first detection information by the movement of the first detected part accompanying the movement of the first actuator part, and the second facing part and the second cam part are A mode in which the sensor unit is configured to detect the second detection information by the movement of the second detected portion accompanying the movement of the second actuator unit can be exemplified.

  In this specific matter, the rotation phase between the first group image carrier and the second group image carrier can be detected with a simple configuration by the single detection sensor.

  In this aspect, the first actuator portion is swingable about the first pivot shaft along the rotation axis direction, and the first cam portion rotates around as the first rotation member rotates. The first detected portion swings by moving and swinging the first facing portion, and the second actuator portion is rotated around the second pivot shaft along the rotation axis direction. The second detected portion swings as the second cam portion rotates and the second facing portion swings as the second rotating member rotates. An example of this is illustrated.

  With this specific matter, detection by the first actuator unit and detection by the second actuator unit can be realized with a simple configuration.

  In this invention, it is preferable to provide the 1st biasing member which urges | biases the said 1st actuator part toward the said 1st gear.

  In this specific matter, the first urging member can reliably slide the first facing portion and the first cam portion, and the first detection information is stably detected by the detection sensor. can do.

  In the present invention, it is preferable that a second urging member for urging the second actuator portion toward the second gear is provided.

  In this specific matter, the second urging member can reliably slide the second facing portion and the second cam portion, and the second detection information is stably detected by the detection sensor. can do.

  In the present invention, the sensor unit includes a light emitting unit and a light receiving unit, and incident light incident on the light receiving unit from the light emitting unit is moved by the movement of the first detected unit as the first actuator unit moves. The second detected portion is moved by the movement of the second detected portion in accordance with the movement of the second actuator portion, and the incident light incident on the light receiving portion from the light emitting portion is blocked or passed by the first detected portion. An optical sensor that detects the presence or absence of the incident light by the light receiving unit can be used by blocking or passing the light by the detection unit.

  In this specific matter, a general-purpose inexpensive optical sensor can be used as the sensor unit.

  In the present invention, the first cam portion of the first rotating member and the second cam portion of the second rotating member may have the same circumferential length.

  According to this specific matter, the first rotating member and the second rotating member can be easily made into the same shape (shared), and thereby, the phase shift of the rotation unevenness caused by the eccentricity or the like can be as much as possible. Therefore, it is possible to make the rotation unevenness periods of the group image carriers easy to coincide with each other and to reduce the component cost.

  In the present invention, it is preferable that the first cam portion of the first rotating member and the second cam portion of the second rotating member have different circumferential lengths.

  In this specific matter, it is possible to easily recognize the difference between the first detection information and the second detection information. Therefore, any one of the first group image carrier and the second group image carrier is selected. It is possible to recognize whether the rotational position of the group image carrier should be changed (for example, which group image carrier should be speeded up or slowed down).

  In this case, since the circumferential lengths of the first cam portion of the first rotating member and the second cam portion of the second rotating member are different from each other, the first rotating member and the second rotating member are Cannot be a common part. Therefore, in the aspect in which the circumferential lengths of the first cam portion of the first rotating member and the second cam portion of the second rotating member are different from each other, the first rotating member includes the first cam. In addition to the first rotation member, the second rotation member is provided in the second rotation member when the first rotation member is the second rotation member, and the second rotation member includes the second rotation member. In addition to the cam portion, it is preferable that the first cam portion provided on the first rotating member when the second rotating member is the first rotating member is provided. According to this aspect, the first rotating member and the second rotating member can be used as a common component, which makes it possible to easily match the rotation unevenness periods of the group image carriers, and to reduce the component cost. Can be kept low.

  In the present invention, it is preferable that at least one of the first rotating member and the second rotating member is a rotating member provided coaxially with an image carrier in a corresponding group image carrier.

  According to this specific matter, in the corresponding group image carrier, detection by the rotating member provided coaxially with the image carrier can reduce the rotation error between the image carrier and the rotating member, and the accuracy is accordingly high. Phase alignment can be performed well.

  Examples of the first rotation member include first drive transmission rotation members such as gears and pulleys that transmit rotation drive from the first drive unit to the first group image carrier. Examples of the second rotation member include second drive transmission rotation members such as gears and pulleys that transmit rotation drive from the second drive unit to the second group image carrier.

  In addition, the first rotating member and the second rotating member include a flange that connects the image carrier and a cup that connects the image carrier to a drive transmission system that transmits drive from the drive unit to the image carrier. An existing member such as a ring member or an additional member such as a disc provided separately in the drive transmission system can be exemplified.

  For example, when the first rotating member and the second rotating member are gears or pulleys, existing gears or pulleys can be used, thereby eliminating the need for a separate rotating member.

  In the present invention, each of the first cam portion and the second cam portion preferably has an ascending slope portion and a descending slope portion.

  In this specific matter, the first facing portion and the second facing portion can be smoothly slid with respect to the first cam portion and the second cam portion, thereby the first group image carrying The impact on the body and the second group image carrier can be suppressed, and a good image can be obtained accordingly.

  In the present invention, both the first facing portion and the second facing portion may have a spherical surface. In this specific matter, the first cam portion and the second cam portion can be smoothly slid with respect to the first opposing portion and the second opposing portion, and thereby the first group image carrying The impact on the body and the second group image carrier can be suppressed, and a good image can be obtained accordingly.

  In the present invention, a plane portion along the outer peripheral surface may be provided between the climbing inclined portion and the descending inclined portion.

  In this specific matter, the detection state or the non-detection state at the plane portion by the detection sensor can be ensured, and the first detection information and the second detection information can be detected stably.

  In the present invention, phase adjusting means for adjusting a rotation phase of the first group image carrier and the second group image carrier to a reference rotation phase as a reference, the first detection information by the detection sensor, and the first Phase detection means for detecting the rotational phase of the first group image carrier and the second group image carrier based on the two detection information, and the phase relative to the reference rotational phase adjusted by the phase adjustment means. A phase difference detection means for detecting a rotation phase difference of the rotation phase detected by the detection means; a rotation timing of the first group image carrier and a second group image carrier based on a detection result by the phase difference detection means; A state in which at least one of the rotation timings is changed to include a rotation phase correction unit that corrects a rotation phase between the first group image carrier and the second group image carrier. The can be exemplified.

  In this particular matter, first, the phase adjusting means adjusts the rotational phase of the first group image carrier and the second group image carrier to the reference rotational phase.

  Thereafter, since the rotational phase of the first group image carrier and the second group image carrier may deviate from the reference rotational phase, the first detection information by the detection sensor and the phase detection unit Based on the second detection information, a rotational phase between the first group image carrier and the second group image carrier is detected, and the phase difference detection unit adjusts the reference rotational phase adjusted by the phase adjustment unit. On the other hand, the rotational phase difference of the rotational phase detected by the phase detection unit is detected, and the rotational phase correction unit detects the rotational timing of the first group image carrier and the first phase based on the detection result by the phase difference detection unit. The rotation timing of the first group image carrier and the second group image carrier is corrected by changing at least one of the rotation timings of the two group image carriers. That. By doing so, the rotational phase of the first group image carrier and the second group image carrier can be matched with the reference rotational phase, and thereby, a phase shift of rotational unevenness due to eccentricity or the like ( (Image shift) can be reduced.

  In the present invention, the first cam portion of the first rotating member and the second cam portion of the second rotating member have the same circumferential length, that is, are detected by the single detection sensor. In the case where the first detection information and the second detection information are configured to be the same, the first rotation member and the second rotation member can be easily shared, but the single detection sensor Since the first detection information and the second detection information detected by the same information are the same, the rotation timing of the first group image carrier and the rotation timing of the second group image carrier are determined by using only this information. Cannot recognize the difference. In other words, only the first detection information and the second detection information may change the rotational position of any group image carrier among the first group image carrier and the second group image carrier. (For example, which group image carrier should be speeded up or slowed down) cannot be recognized.

  In this case, the rotational position of at least one of the first group image carrier and the second group image carrier is changed (for example, the speed of any one of the group image carriers is increased, or And a check means for confirming whether or not the rotational phase is away from the reference rotational phase. The phase adjusting unit and the rotational phase correcting unit are configured to perform the confirmation when changing a rotational position of at least one of the first group image carrier and the second group image carrier. After confirming whether or not the rotational phase is separated from the reference rotational phase by means, if the rotational phase is separated from the reference rotational phase, the at least one group image carrier of the at least one group image carrier The rotation position can be reversed (for example, when the speed of any one of the group image carriers is increased, the rotation position is decreased, or when the speed is decreased, the rotation speed is increased). In this case, it takes a long time to detect the rotational phase, resulting in a complicated control configuration.

  From this viewpoint, as described above, it is preferable that the first cam portion of the first rotating member and the second cam portion of the second rotating member have different lengths in the circumferential direction.

  By doing so, which of the first group image carrier and the second group image carrier is to be changed in rotation position (for example, which group image carrier is increased in speed). Without delaying the time required to check whether the rotational phase is away from the reference rotational phase, and so on. Moreover, the control configuration is not complicated.

  In the present invention, the phase detection means measures a phase time between the detection start of the first detection information by the detection sensor and the detection start of the second detection information by the detection sensor, or the detection An aspect of measuring the phase time between the end of detection of the first detection information by the sensor and the end of detection of the second detection information by the detection sensor can be exemplified.

  In this specific matter, the rotational phases of the first group image carrier and the second group image carrier can be detected with a simple control configuration.

  By the way, only one of the first group image carrier and the second group image carrier is driven, and the rotational phase of the first group image carrier and the second group image carrier is the reference. Depending on the rotational positions of the first group image carrier and the second group image carrier, as in the case where the rotational phase is completely different, the first detection time of the first group image carrier and the first A part of the second detection time of the two-group image carrier may overlap, or one of the first detection time and the second detection time may overlap the whole or part of the other. If it does so, the detection start and detection end by the said detection sensor will exist only in one place.

  From this point of view, when there is only one detection start by the detection sensor, the phase detection means uses at least one of the first group image carrier and the second group image carrier by the detection sensor. After rotating so that the detection start is in two places, the phase time is measured, or when there is only one detection end by the detection sensor, the first group image carrier and the first It is preferable to measure the phase time after rotating at least one of the two group image carriers so that the detection by the detection sensor ends at two places.

  In this specific matter, the rotational phases of the first group image carrier and the second group image carrier can be reliably detected.

  In the present invention, the reference rotation phase adjusted by the phase adjustment unit is stored in advance in a storage unit, and the phase difference detection unit is configured to store the phase detection unit with respect to the reference rotation phase stored in the storage unit. It is preferable to detect the rotational phase difference between the rotational phases detected in (1).

  In this specific matter, for example, if the reference rotation phase is adjusted by the phase adjustment unit at the time of initial driving and / or every predetermined period, and stored in the storage unit at that time, the useless phase adjustment unit Thus, the adjustment operation by can be omitted, and the operation control time can be shortened accordingly.

  In the present invention, the rotational phase correction unit drives at least one of the first drive unit and the second drive unit based on a detection result by the phase difference detection unit, so that the first group image carrier For example, the rotation phase of the first group image carrier and the second group image carrier can be corrected by changing at least one of the rotation timing and the rotation timing of the second group image carrier.

  In this specific matter, the first driving unit and the second driving unit can directly change the rotation timing of the first group image carrier and the rotation timing of the second group image carrier, respectively. The rotational phase can be accurately corrected.

  In the present invention, it is preferable that the phase detector detects the rotational phase during a printing operation.

  In this specific matter, since the rotational phase is detected during the printing operation, it is not necessary to separately drive the first group image carrier and the second group image carrier for the detection of the rotational phase. Thus, the rotational phase can be detected efficiently.

  In the present invention, the first group image carrier is for performing monochrome (monochrome) image formation, and the second group image carrier is a color device in cooperation with the first group image carrier. A mode for performing the image formation of the above can be exemplified.

  In this specific matter, the image forming apparatus according to the present invention can be a color image forming apparatus. In addition, the driving device according to the present invention can be a driving device applicable to a color image forming apparatus. That is, the rotation unevenness between the first group image carrier for forming a monochrome image and the second group image carrier for forming a color image in cooperation with the first group image carrier. By performing the phase matching by the single detection sensor, it is possible to reduce the color shift due to the phase shift and to realize a cost reduction.

  As described above, according to the image forming apparatus and the driving device of the present invention, the single detection sensor that detects the first detection information and detects the second detection information is provided. The number of detection sensors that perform phase alignment due to uneven rotation of each image carrier can be reduced as much as possible, whereby the apparatus configuration can be simplified and the cost can be reduced.

  Furthermore, the detection configuration of the first detection information and the second detection information can be easily realized by using the detection object by the detection sensor as the first rotation member and the second rotation member.

  In addition, the single detection sensor detects rotation timing detection information by the first cam portion of the first rotation member as the first detection information, and the second rotation member as the second detection information. By detecting the detection information of the rotation timing by the second cam portion, the information on the first rotation angle of the first group image carrier as the first detection information of the first rotation member. And the second rotation angle information of the second group image carrier can be detected as the second detection information of the second rotating member. Thereby, the rotation phase of the first group image carrier and the second group image carrier can be easily detected by the single detection sensor.

1 is a side view schematically showing a color image forming apparatus to which an embodiment of a driving device according to the present invention is applied. FIG. 2 is a perspective view showing in detail a driving device in the color image forming apparatus shown in FIG. 1. FIG. 3 is a system configuration diagram schematically illustrating a drive transmission system of the drive device illustrated in FIG. 2, and is a diagram illustrating a gear train and a detection sensor that transmit rotational drive from the first and second drive units to the photosensitive drum. . It is a figure for demonstrating the detection state of the 1st gear by the detection sensor in 1st Embodiment, and a 2nd gear, Comprising: The figure (a) is the schematic side view, The figure (b) is the schematic bottom face. FIG. 4C is a schematic cross-sectional view taken along line A1-A1 in FIG. 1A, and FIG. 4D is a schematic cross-sectional view taken along line A2-A2 in FIG. FIG. (E) is a schematic cross-sectional view of the portion of the first facing portion that faces the outer peripheral surface of the first gear as viewed from the direction of the rotation axis of the first gear, and FIG. It is the schematic sectional drawing which looked at the portion of the 2nd countering part which counters the outer peripheral surface of a gear from the rotation axis direction of the 2nd gear. It is a figure for demonstrating 1st detection information and 2nd detection information, Comprising: It is a figure which shows the output signal from a detection sensor. It is a figure for demonstrating 2nd Embodiment, Comprising: The figure (a) is the schematic side view, The figure (b) is the schematic bottom view, The figure (c) is a figure (a). It is a schematic sectional drawing in alignment with the A1-A1 line in the inside, and FIG. (D) is a schematic sectional drawing in alignment with the A2-A2 line in FIG. It is a figure which shows the state of the disc provided coaxially with the photoconductor as a 1st and 2nd rotation member. It is a control block diagram which shows the system configuration | structure which operates the drive device of 1st and 2nd embodiment. FIG. 6A is a diagram for explaining a phase shift of rotation unevenness of the first group photoconductor and the second group photoconductor, and FIG. (A) is a period showing a displacement state of rotation unevenness generated in the first group photoconductor. FIG. 5B is a graph showing a state in which the period indicating the displacement state of the rotation unevenness generated in the second group photoconductor is deviated, and FIG. (C) is a graph showing the period when the rotational phase is adjusted to the reference rotational phase. FIG. 6A is a diagram for explaining operation control of a rotational phase, and FIG. 5A is a diagram illustrating an output signal from a detection sensor when the rotational phase is adjusted to a reference rotational phase, and FIG. FIG. 5C is a diagram showing the detection state, FIG. 5C is a diagram showing an output signal from the detection sensor when the rotational phase is deviated from the reference rotational phase, and FIG. FIG. It is a figure which shows the output signal for demonstrating the state where the detection start and detection end by a detection sensor exist only in one part, Comprising: Part (a) of FIG. (B) is a figure which shows the state which the 2nd detection time has overlapped with the 1st detection time.

  Embodiments according to the present invention will be described below with reference to the drawings. The following embodiments are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

  FIG. 1 is a side view schematically showing a color image forming apparatus D to which an embodiment of a driving apparatus according to the present invention is applied.

  A color image forming apparatus D shown in FIG. 1 is a document reading device B that reads an image of a document, and records an image of the document read by the document reading device B or an image received from the outside in color or single color on plain paper or the like. The apparatus main body A which records and forms on a material is provided.

  In the document reading apparatus B, when the document is set on the document set tray 41, the pickup roller 44 is pressed against the surface of the document and rotated, the document is pulled out from the tray 41, and passes between the suction roller 45 and the separation pad 46. After being separated one by one, it is transported to the transport path 47.

  In the conveyance path 47, the leading edge of the document contacts the registration roller 49 and is aligned parallel to the registration roller 49, and then the document is conveyed by the registration roller 49 and passes between the document guide 51 and the reading glass 52. At this time, the light from the light source of the first scanning unit 53 is irradiated on the surface of the document through the reading glass 52, and the reflected light is incident on the first scanning unit 53 through the reading glass 52. Reflected by the mirrors of the first and second scanning units 53 and 54 and guided to the imaging lens 55, an image on the surface of the document is formed on a CCD (Charge Coupled Device) 56 by the imaging lens 55. The CCD 56 reads an image on the surface of the document and outputs image data indicating the image. Further, the document is transported by the transport roller 57 and discharged to the document discharge tray 59 via the discharge roller 58.

  The document reading device B can read a document placed on the document table glass 61. The registration roller 49, the document guide 51, the document discharge tray 59, and the like and the members above them form an integrated cover body, and an axis line along the document transport direction on the back side of the document reading apparatus B It is pivotally supported so that it can be opened and closed. When the upper cover body is opened, the document table glass 61 is opened, and a document can be placed on the document table glass 61. The document placed on the document table glass 61 is held by the cover body when the cover body is closed. When a document reading instruction is issued, the surface of the document on the document table glass 61 is exposed by the first scanning unit 53 while the first and second scanning units 53 and 54 are moved in the sub-scanning direction. The reflected light from the document surface is guided to the imaging lens 55 by the first and second scanning units 53 and 54, and is imaged on the CCD 56 by the imaging lens 55, where the document image is read. At this time, the first and second scanning units 53 and 54 are moved while maintaining a predetermined speed relationship with each other, and reflection of the document surface → first and second scanning units 53 and 54 → imaging lens 55 → CCD 56 is performed. The positional relationship between the first and second scanning units 53 and 54 is always maintained so that the length of the optical path of the light does not change, and thereby the focus of the image on the original surface on the CCD 56 is always accurately maintained.

  The entire original image read in this way is sent and received as image data to the apparatus main body A of the color image forming apparatus D, and the image is recorded on the recording material in the apparatus main body A.

  On the other hand, the apparatus main body A of the color image forming apparatus D forms a plurality of images using the photosensitive drums 3 (3a, 3b, 3c, 3d) that act as a plurality of image carriers corresponding to the respective images. These images are superimposed. The apparatus main body A includes an exposure device 1, a developing device 2 (2a, 2b, 2c, 2d), a photosensitive drum 3 (3a, 3b, 3c, 3d) arranged in parallel along the recording material conveyance direction, and a charger 5. (5a, 5b, 5c, 5d), cleaner device 4 (4a, 4b, 4c, 4d), intermediate transfer belt device 8 including intermediate transfer roller 6 (6a, 6b, 6c, 6d) acting as a transfer unit, fixing The apparatus 12 includes a transport device 18, a paper feed tray 10 that functions as a paper feed unit, and a paper discharge tray 15 that functions as a paper discharge unit.

  The image data handled in the apparatus main body A of the color image forming apparatus D is one corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color ( For example, it corresponds to a monochrome image using black). Accordingly, the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), and the cleaner device 4 (4a, 4b, 4c, 4d) and four intermediate transfer rollers 6 (6a, 6b, 6c, 6d) are provided so as to form four types of images corresponding to the respective colors. Is associated with black, b with cyan, c with magenta, and d with yellow to form four image stations. Hereinafter, the description will be made with the suffixes a to d omitted.

  The photoconductor drum 3 is disposed at substantially the center in the vertical direction of the apparatus main body A. The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential, and a charger type charger is used in addition to a contact type roller type or brush type charger. .

  Here, the exposure apparatus 1 is a laser scanning unit (LSU) having a laser light source and a reflection mirror, and exposes the surface of the charged photosensitive drum 3 according to image data, and responds to the image data on the surface. An electrostatic latent image is formed.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with (K, C, M, Y) toner. The cleaner device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  In addition to the intermediate transfer roller 6, the intermediate transfer belt device 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7 that acts as an intermediate transfer member, an intermediate transfer belt drive roller 21, a driven roller 22, and a tension roller. 23 and an intermediate transfer belt cleaning device 9.

  Roller members such as the intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, and the tension roller 23 stretch and support the intermediate transfer belt 7, and the intermediate transfer belt 7 is supported in a predetermined conveyance direction (arrow in the figure). Move around in the C direction).

  The intermediate transfer roller 6 is rotatably supported inside the intermediate transfer belt 7 and is pressed against the photosensitive drum 3 via the intermediate transfer belt 7, and transfers the toner image on the photosensitive drum 3 to the intermediate transfer belt 7. A transfer bias is applied.

  The intermediate transfer belt 7 is provided so as to be in contact with each photoconductive drum 3, and a color toner image (each color is transferred by sequentially superimposing and transferring the toner image on the surface of each photoconductive drum 3 onto the intermediate transfer belt 7. Toner image). Here, the transfer belt 7 is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 that is in pressure contact with the inner side (back surface) of the intermediate transfer belt 7. A high voltage transfer bias (for example, a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. Here, the intermediate transfer roller 6 is a roller based on a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the recording material.

  The apparatus main body A of the color image forming apparatus D further includes a secondary transfer apparatus 11 including a transfer roller 11a that functions as a transfer unit. The transfer roller 11a is in contact with the opposite side (outside) of the intermediate transfer belt 7 from the intermediate transfer belt drive roller 21.

  As described above, the toner images on the surfaces of the respective photosensitive drums 3 are stacked on the intermediate transfer belt 7 and become a color toner image indicated by the image data. The stacked toner images of the respective colors are transported together with the intermediate transfer belt 7 and transferred onto the recording material by the secondary transfer device 11.

  The intermediate transfer belt 7 and the transfer roller 11a of the secondary transfer device 11 are pressed against each other to form a nip region. Further, a voltage (for example, a polarity (+) opposite to the toner charging polarity (−)) is applied to the transfer roller 11a of the secondary transfer device 11 to transfer the toner image of each color on the intermediate transfer belt 7 onto the recording material. Is applied). Further, in order to constantly obtain the nip region, either the transfer roller 11a of the secondary transfer device 11 or the intermediate transfer belt drive roller 21 is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller. (Elastic rubber roller, foaming resin roller, etc.).

  In addition, the toner image on the intermediate transfer belt 7 may not be completely transferred onto the recording material by the secondary transfer device 11, and the toner may remain on the intermediate transfer belt 7. Causes color mixing. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning device 9. The intermediate transfer belt cleaning device 9 includes, for example, a cleaning blade that comes into contact with the intermediate transfer belt 7 as a cleaning member, and residual toner can be removed and collected by the cleaning blade. The driven roller 22 supports the intermediate transfer belt 7 from the inner side (back side), and the cleaning blade is in contact with the intermediate transfer belt 7 so as to press it toward the driven roller 22 from the outer side.

  The paper feed tray 10 is a tray for storing recording materials, and is provided below the image forming unit of the apparatus main body A. The paper discharge tray 15 provided on the upper side of the image forming unit is a tray for placing printed recording materials face down.

  Further, the apparatus main body A is provided with a conveying device 18 for sending the recording material of the paper feed tray 10 to the paper discharge tray 15 via the secondary transfer device 11 and the fixing device 12. The transport device 18 has an S-shaped transport path S, and along this transport path S, a pickup roller 16, each transport roller 13, a pre-registration roller 19, a registration roller 14, a fixing device 12, and a paper discharge. A conveying member such as a roller 17 is arranged.

  The pickup roller 16 is a pull-in roller that is provided at the downstream end of the paper feed tray 10 in the recording material conveyance direction and supplies the recording material from the paper feed tray 10 to the conveyance path S one by one. Each conveyance roller 13 and the pre-registration roller 19 are small rollers for promoting and assisting the conveyance of the recording material. Each transport roller 13 is provided at a plurality of locations along the transport path S. The pre-registration roller 19 is provided in the immediate vicinity upstream of the registration roller 14 in the conveyance direction, and conveys the recording material to the registration roller 14.

  The registration roller 14 temporarily stops the recording material conveyed by the pre-registration roller 19, aligns the leading end of the recording material, and is on the intermediate transfer belt 7 in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. The recording material is conveyed with good timing in accordance with the rotation of the photosensitive drum 3 and the intermediate transfer belt 7 so that the color toner image is transferred onto the recording material.

  For example, the registration roller 14 performs recording so that the front end of the color toner image on the intermediate transfer belt 7 matches the front end of the image forming range on the recording material in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. Transport material.

  The fixing device 12 includes a heat roller 31 and a pressure roller 32. The heat roller 31 and the pressure roller 32 sandwich and transport the recording material.

  The temperature of the heat roller 31 is controlled so as to reach a predetermined fixing temperature, and the recording material is thermocompression-bonded together with the pressure roller 32 to melt, mix, and press the toner image transferred to the recording material. On the other hand, it has a function of heat fixing.

  The recording material after the fixing of the toner images of the respective colors is discharged onto the paper discharge tray 15 by the paper discharge roller 17.

  It is also possible to form a monochrome image using at least one of the four image forming stations and transfer the monochrome image to the intermediate transfer belt 7 of the intermediate transfer belt device 8. Similarly to the color image, this monochrome image is also transferred from the intermediate transfer belt 7 to the recording material and fixed on the recording material.

  Further, in the case of forming not only the front (front) surface of the recording material but also double-sided image formation, the recording material is fixed on the surface of the recording material by the fixing device 12, and then the recording material is discharged on the material conveyance path S. In the middle of conveying by the above, the paper discharge roller 17 is stopped and then reversely rotated, the recording material is passed through the front / back reversing path Sr, the recording material is reversed, and the recording material is guided to the registration roller 14 again. Similarly to the front surface of the recording material, an image is recorded and fixed on the back surface of the recording material, and the recording material is discharged to the paper discharge tray 15.

  The color image forming apparatus D further includes a driving device 100a (not shown in FIG. 1; see FIGS. 2 and 3 described later) for driving the photosensitive drum 3.

[Configuration of drive unit]
Next, the drive device 100a will be described with reference to FIGS. In the following description, the last symbol of the photosensitive drum 3 and the last symbol of the developing device 2 are not omitted, and the photosensitive drums 3a, 3b, 3c, 3d and the developing device (here, the developing unit) 2a are omitted. , 2b, 2c, 2d.

  FIG. 2 is a perspective view showing in detail the driving device 100a in the color image forming apparatus D shown in FIG. FIG. 3 is a system configuration diagram schematically showing a drive transmission system of the drive device 100a shown in FIG. 2, and the photosensitive drums 3a, 3b, 3c, 3d from the first and second drive units 110, 120 are shown. It is a figure which shows the gear train and detection sensor 170 which transmit the rotational drive to. In FIG. 2, the detection sensor 170 is not shown.

  The color image forming apparatus D includes a first group photoconductor 30a (first group image carrier) to which at least one photoconductor drum (here, the black photoconductor drum 3a) among the photoconductor drums 3a, 3b, 3c, and 3d belongs. Example) and the remaining photoconductor drums 3b, 3c, 3d (here, the cyan photoconductor drum 3b, the magenta photoconductor drum 3c, and the yellow photoconductor drum 3d) to which the second group photoconductor 30b (second An example of a group image carrier. That is, here, the first group photoconductor 30a is for performing monochrome image formation (monochrome printing), and the second group photoconductor 30b cooperates with the first group photoconductor 30a to produce a full color. This is for image formation.

  The driving device 100a includes a first driving unit 110, a second driving unit 120, a first rotating member (here, a first driving transmission rotating member) 150, and a second rotating member (here, a second driving transmission rotation). Member) 160.

  The first drive unit 110 is for driving the first group photoconductor 30a. The second drive unit 120 is for driving the second group photoconductor 30b. Here, the first driving unit 110 and the second driving unit 120 are stepping motors.

  The first driving transmission rotating member 150 transmits rotational driving from the first driving unit 110 to the first group photoconductor 30a, and here, the first shaft gear 111, the first intermediate gear 112, It comprises a black photosensitive member driving gear 130. The second drive transmission rotation member 160 transmits the rotation drive from the second drive unit 120 to the second group photoconductor 30b. Here, the second shaft gear 121 and the second to fourth intermediate gears. 122 to 124, and color (for cyan, magenta, and yellow) photoreceptor driving gears 140b to 140d. Note that the rotation axes of these gears are parallel to each other.

  Specifically, the black photoconductor drive gear 130 is coaxially connected to the rotation shaft of the black photoconductor drum 3 a and meshes with the first intermediate gear 112. A first shaft gear 111 provided on the rotation shaft of the first drive unit 110 meshes with the first intermediate gear 112. As a result, when the first driving unit 110 is driven to rotate, the black shaft connected to the black photosensitive member driving gear 130 via the first shaft gear 111, the first intermediate gear 112, and the black photosensitive member driving gear 130. The photosensitive drum 3a can be rotated.

  The cyan photoconductor drive gear 140 b is coaxially connected to the rotation shaft of the cyan photoconductor drum 3 b and meshes with the third intermediate gear 123. The magenta photoconductor drive gear 140c is coaxially connected to the rotation shaft of the magenta photoconductor drum 3c, and meshes with the second intermediate gear 122, the third intermediate gear 123, and the fourth intermediate gear 124. The yellow photoconductor drive gear 140 d is coaxially connected to the rotation shaft of the yellow photoconductor drum 3 d and meshes with the fourth intermediate gear 124. A second shaft gear 121 provided on the rotation shaft of the second drive unit 120 meshes with the second intermediate gear 122. As a result, the second driving unit 120 is driven to rotate, whereby the magenta connected to the magenta photosensitive member driving gear 140c via the second shaft gear 121, the second intermediate gear 122, and the magenta photosensitive member driving gear 140c. The cyan photosensitive drum 3b connected to the cyan photosensitive drum driving gear 140b is connected to the cyan photosensitive drum 3c via the magenta photosensitive drum driving gear 140c, the third intermediate gear 123, and the cyan photosensitive drum driving gear 140b. Further, the yellow photosensitive drum 3d connected to the yellow photosensitive member driving gear 140d can be rotated via the magenta photosensitive member driving gear 140c, the fourth intermediate gear 124, and the yellow photosensitive member driving gear 140d. it can.

  As a result, the second driving unit 120 of the color photosensitive drums 3b, 3c, and 3b can be made common. In addition, the first driving unit 110 can rotate the photosensitive drum 3a independently during monochrome printing.

  The first drive unit 110 also drives the black development unit 2a, and the second drive unit 120 also drives the cyan development unit 2b, the magenta development unit 2c, and the yellow development unit 2d. It is like that.

  Here, the black photoconductor drive gear 130 is the first gear that acts as the first rotating member 150, and the cyan photoconductor drive gear among the color photoconductor drive gears 140 (140b, 140c, 140d). Reference numeral 140 b denotes a second gear that functions as the second rotating member 160.

(First embodiment)
In the image forming apparatus D shown in FIG. 1, the driving device 100a shown in FIGS. 2 and 3 detects the first detection information for recognizing the rotation timing of the first group photoconductor 30a, and the second group photosensitivity. A single detection sensor 170 (see FIG. 3) for detecting second detection information for recognizing the rotation timing of the body 30b is further provided. The first detection information and the second detection information are recognized by the drive control unit 200 described later.

  FIG. 4 is a view for explaining detection states of the first gear 130 and the second gear 140 by the detection sensor 170 in the first embodiment. FIG. 4A shows a schematic side view thereof. FIG. 4B shows a schematic bottom view thereof. FIG. 4C shows a schematic cross-sectional view along the line A1-A1 in FIG. FIG. 4D shows a schematic cross-sectional view along the line A2-A2 in FIG. 4E is a schematic cross-sectional view of a portion of the first facing portion 174 facing the outer peripheral surface (hereinafter referred to as the first outer peripheral surface) α1 of the first gear 130 as viewed from the rotational axis direction of the first gear 130. is there. 4F is a schematic cross-sectional view of the portion of the second facing portion 175 facing the outer peripheral surface (hereinafter referred to as the second outer peripheral surface) α2 of the second gear 140 as viewed from the rotational axis direction of the second gear 140. FIG.

  FIG. 5 is a diagram for explaining the first detection information and the second detection information, and shows an output signal from the detection sensor 170.

  As shown in FIG. 4, at least a part of the first outer peripheral surface α1 of the first gear 130 in the rotational axis direction (the arrow X direction in FIG. 4) (here, a part excluding the gear tooth part in the rotational axis direction X). In addition, a first cam portion 131 is provided in a part of the circumferential direction (Y1 direction in FIG. 4A). The 1st cam part 131 consists of the 1st convex part or 1st recessed part (here 1st convex part) along this circumferential direction Y1. In addition, on the second outer peripheral surface α2 of the second gear 140, at least partly in the rotational axis direction X (here, part excluding gear tooth portions in the rotational axis direction X) and circumferentially (Y2 in FIG. 4A). The second cam portion 141 is provided in a part of the direction. The 2nd cam part 141 consists of the 2nd convex part or 2nd recessed part (here 2nd convex part) along this circumferential direction Y2. In addition, the 1st cam part 131 can be provided in the arbitrary positions of 1st outer peripheral surface (alpha) 1 in the circumferential direction Y1. Moreover, the 2nd cam part 141 can be provided in the arbitrary positions of 2nd outer peripheral surface (alpha) 2 in the circumferential direction Y2.

  And the detection sensor 170 detects the detection information of the rotation timing by the 1st cam part 131 of the 1st gear 130 as 1st detection information, and the 2nd cam part 141 of the 2nd gear 140 as 2nd detection information. It is configured to detect rotation timing detection information.

  According to the first embodiment, the first detection information is detected by the single detection sensor 170, and the second detection information is detected. As a result, the first group photoconductor 30a and the second group photoconductor 30b can be connected to each other with as few sensors as possible to perform phase alignment due to rotation unevenness between the first group photoconductor 30a and the second group photoconductor 30b. The rotational phase can be detected, which makes it possible to simplify the device configuration and reduce the cost. Here, the phase due to rotation unevenness between the first group photoconductor 30a for forming a monochrome image and the second group photoconductor 30b for forming a full color image in cooperation with the first group photoconductor 30a. By performing the alignment with the single detection sensor 170, it is possible to reduce the color shift due to the phase shift and to realize a cost reduction.

  In the first embodiment, the first detection information and the second detection information 170 can be recognized by a single detection sensor 170 so that the difference between the rotation timing of the first group photoconductor 30a and the rotation timing of the second group photoconductor 30b can be recognized. The detection information is different from each other. That is, the first detection information is information that can be recognized as information of the first group photoconductor 30a with respect to the second detection information, and the second detection information is relative to the first detection information. The information can be recognized as information on the second group photoconductor 30a. Specifically, the first cam portion 131 of the first gear 130 and the second cam portion 141 of the second gear 140 have different circumferential lengths.

  As described above, the first detection information and the second detection information can be recognized by the single detection sensor 170 so that the difference between the rotation timing of the first group photoconductor 30a and the rotation timing of the second group photoconductor 30b can be recognized. Are different from each other, it is possible to easily recognize the difference between the first detection information and the second detection information. Therefore, of the first group photoconductor 30a and the second group photoconductor 30b. Recognizing which group photoconductor rotation position should be changed in which direction (for example, which group photoconductor speed should be increased or delayed). Can do.

  Here, the detection sensor 170 includes a first actuator unit 171, a first detected unit 172, a second actuator unit 176, a second detected unit 177, and a sensor unit 173.

  The first actuator portion 171 is movable along a direction that intersects the rotational axis direction X of the first gear 130. The first detected part 172 is provided in the first actuator part 171. The second actuator portion 176 is movable along a direction that intersects the rotational axis direction X of the second gear 140. The second detected part 177 is provided in the second actuator part 176. The sensor unit 173 detects the first detected unit 172 and the second detected unit 177.

  The first actuator portion 171 is provided with a first facing portion 174 that faces the first outer peripheral surface α1 of the first gear 130. The second actuator portion 176 is provided with a second facing portion 175 that faces the second outer peripheral surface α2 of the second gear 140.

  In the first embodiment, from the viewpoint of being close to the first gear 130, the detection target of the second gear 140 by the detection sensor 170 is the cyan photoconductor drive gear 140b. Further, the first gear 130 may be the intermediate gear 112. The second gear 140 may be any of the drive gears 140c and 140d and the intermediate gears 121 to 123.

  In the first embodiment, the first detection information includes information on the first rotation angle θ1 of the first group photoconductor 30a. The second detection information includes information on the second rotation angle θ2 of the second group photoconductor 30b. Thereby, the rotation phase between the first group photoconductor 30a and the second group photoconductor 30b can be detected by the detection sensor 170 with a relatively simple configuration.

  Further, the first rotation angle θ1 and the second rotation angle θ2 are different. Here, the peripheral speeds of the first gear 130 and the second gear 140 are equal. Thereby, the difference between the first detection information and the second detection information can be easily recognized.

  Specifically, as shown in FIG. 5, the first detection information includes a first detection time t1 when the first rotation angle θ1 of the first group photoconductor 30a is detected, and the second detection information is the second group. It includes a second detection time t2 (here, t1> t2) different from the first detection time t1 at which the second rotation angle θ2 (here, θ1> θ2) of the photoconductor 30b is detected. Note that the rotational phases of the first group photoconductor 30a and the second group photoconductor 30b are the detection start st of the first detection time t1 of the first group photoconductor 30a and the second detection time t2 of the second group photoconductor 30b. Detection by detecting a difference Tr (Tr1) from the detection start st of the first detection time ed of the first detection time t1 of the first group photoconductor 30a and a second detection time t2 of the second photoconductor 30b. It can be detected by obtaining the difference Tr (Tr2) from the detection end ed.

  In the first embodiment, the first facing portion 174 in the first actuator portion 171 and the first cam portion 131 in the first gear 130 are moved by the movement of the first detected portion 172 as the first actuator portion 171 swings. The sensor unit 173 is configured to detect the first detection time t <b> 1 by being in a detection state and a non-detection state. Further, the second opposing portion 175 in the second actuator portion 176 and the second cam portion 141 in the second gear 140 are detected by the sensor portion 173 by the movement of the second detected portion 177 accompanying the swing of the second actuator portion 176. The second detection time t2 is formed by detecting the state and the non-detection state.

  In the present embodiment, the first actuator portion 171 is swingable about the first pivot shaft Q1 along the rotation axis direction X. In the first actuator portion 171, the first detected portion 172 oscillates as the first cam portion 131 circulates with the rotation of the first gear 130 and the first opposing portion 174 oscillates. ing.

  Further, the second actuator portion 176 is swingable about the second pivot shaft Q2 along the rotation axis direction X. In the second actuator portion 176, the second detected portion 177 swings as the second cam portion 141 rotates and the second facing portion 175 swings as the second gear 140 rotates. ing.

  The first facing portion 174 is outside the first straight line φ1 that passes through the center of the first pivot shaft Q1 and the center of rotation of the first gear 130 when the first facing portion 174 is not in contact with the first cam portion 131 (first It is arranged on the upstream side Y3 in the rotation direction of the gear 130. Accordingly, in the first actuator portion 171, the first facing portion 174 is moved around the first pivot shaft Q1 in the B1 direction (clockwise direction) in FIG. 4 by the first cam portion 131 of the rotating first gear 130. Can do. Further, the second facing portion 175 is outside the second imaginary straight line φ2 passing through the center of the second pivot shaft Q2 and the center of rotation of the second gear 140 in a state where it does not contact the first cam portion 131 (second The gear 140 is disposed on the downstream side in the rotational direction Y3 of the gear 140. Thus, in the second actuator portion 176, the second facing portion 175 is moved in the B2 direction (counterclockwise direction) in FIG. 4 around the second pivot shaft Q2 by the second cam portion 141 of the rotating second gear 140. be able to.

  In the driving device 100a, the first gear 130 and the second gear 140 rotate when detecting the first detection time t1 and the second detection time t2.

  In the first gear 130, when the first cam portion 131 moves to the first facing portion 174, the first facing portion 174 is pushed up by one end portion of the first cam portion 131. If it does so, the 1st to-be-detected part 172 will fall via the 1st actuator part 171, and the sensor part 173 will be in a non-detection state (1st to-be-detected state) in the 1st detection position (beta) 1 (refer FIG.4 (e)) of the 1st cam part 131. From the state where the detection unit 172 is shielded from light) to the detection state (the state where the first detected portion 172 is not shielded) or from the detection state to the non-detection state (here, from the detection state to the non-detection state). This time is the detection start st of the first detection time t1 by the detection sensor 170 (see FIG. 5). When the first gear 130 further rotates, the first facing portion 174 descends at the other end of the first cam portion 131. Then, the first detected portion 172 is raised via the first actuator portion 171, and the sensor portion 173 is detected from the detection state to the non-detection state or from the non-detection state at the first detection position β1 of the first cam portion 131 (here. Then, the non-detection state changes to the detection state. This is the end of detection ed of the first detection time t1 by the detection sensor 170 (see FIG. 5).

  Similarly, in the second gear 140, when the second cam portion 141 shifts to the second facing portion 175, the second facing portion 175 is pushed up at one end portion of the second cam portion 141. If it does so, the 2nd to-be-detected part 177 will fall via the 2nd actuator part 176, and the sensor part 173 will be in a detection state from a non-detection state or 2nd detection position (beta) 2 (refer FIG.4 (f)) of the 2nd cam part 141 From the detection state to the non-detection state (here, from the detection state to the non-detection state). This time is the detection start st of the second detection time t2 by the detection sensor 170 (see FIG. 5). When the second gear 140 further rotates, the second facing portion 175 descends at the other end of the second cam portion 141. Then, the second detected portion 177 is raised via the second actuator portion 171, and the sensor portion 173 at the second detection position β2 of the second cam portion 141 is detected from the non-detected state or the non-detected state (here. Then, the non-detection state changes to the detection state. This is the end of detection ed of the second detection time t2 by the detection sensor 170 (see FIG. 5).

  As described above, by detecting the first rotation angle θ1 of the first group photoconductor 30a, the first detection time t1 of the first gear 130 can be detected, and the first group photoconductor 30b first is detected. By detecting the second rotation angle θ2 different from the rotation angle θ1, a second detection time t2 different from the first detection time t1 of the second gear 140 can be detected. Thereby, the rotation phase of the first group photoconductor 30a and the second group photoconductor 30b can be easily detected by the single detection sensor 170.

  In the first embodiment, as shown in FIGS. 4 (e) and 4 (f), the first cam portion 131 and the second cam portion 141 are both ascending inclined portions 131a and 141a and descending inclined portions 131b and 141b. And have. By doing so, the first opposing portion 174 and the second opposing portion 175 can be smoothly slid with respect to the first cam portion 131 and the second cam portion 141, and thereby the first group photoconductor 30a. In addition, the impact due to the sliding on the second group photoconductor 30b can be suppressed, and a good image can be obtained accordingly.

  In addition, the 1st detection position (beta) 1 is made into the middle position of the climbing inclination part 131a of a 1st convex part, and the middle position of the downward inclination part 131b here. Here, the second detection position β2 is the midway position of the climbing slope 141a of the second convex part and the midway position of the downward slope 141b.

  Further, as shown in FIG. 4E, the first facing portion 174 has a curved surface shape (for example, a roller member) or a spherical shape. Further, as shown in FIG. 4F, the second facing portion 175 has a curved surface shape (for example, a roller member) or a spherical shape. By doing so, the first cam portion 131 and the second cam portion 141 can be smoothly slid with respect to the first facing portion 174 and the second facing portion 175, whereby the first group photoconductor 30a. In addition, the impact on the second group photoconductor 30b can be suppressed, and a good image can be obtained accordingly.

  Further, a plane portion 131c along the first outer peripheral surface α1 of the first gear 130 is formed between the ascending slope portion 131a and the descending slope portion 131b. A plane portion 141c along the second outer peripheral surface α2 of the second gear 140 is formed between the ascending slope portion 141a and the descending slope portion 141b. By doing so, it is possible to secure the detection state or the non-detection state at the flat surface portions 131c and 141c by the detection sensor 170, and it is possible to detect the first detection time t1 and the second detection time t2 more stably.

  Here, the sensor unit 173 is a transmissive optical sensor including a light emitting unit 173a and a light receiving unit 173b. This sensor unit 173 blocks or passes incident light incident on the light receiving unit 173b from the light emitting unit 173a at the first detected unit 172 by the movement of the first detected unit 172 accompanying the swing of the first actuator unit 171. In addition, incident light incident on the light receiving unit 173b from the light emitting unit 173a is blocked or passed by the second detected unit 177 by the movement of the second detected unit 177 accompanying the swing of the second actuator unit 176. Thus, the presence or absence of the incident light is detected by the light receiving unit 173b. The sensor unit 173 may be a reflection type optical sensor.

  The rotation angle of the first cam portion 131 is the first rotation angle θ1, and the rotation angle of the second cam portion 141 is the second rotation angle θ2. Further, the first facing portion 174 in the first actuator portion 171 and the second facing portion 175 in the second actuator portion 176 have the same shape.

   In the first embodiment, as shown in FIG. 4A, the first actuator member 171 is urged toward the first gear 130 by the first urging member 180a. Further, the second urging member 180 b urges the second actuator portion 176 toward the second gear 140. By doing so, the first and second urging members 180a and 180b can surely make the first facing portion 174 and the second facing portion 175 and the first cam portion 131 and the second cam portion 141 slidably contact each other. Thus, the first detection time t1 and the second detection time t2 can be detected by the detection sensor 170 stably. When the first actuator part 171 is provided above the first gear 130, the first actuator part 171 is urged toward the first gear 130 by its own weight without providing the first urging member 180a. You may be comprised so that. When the second actuator portion 176 is provided above the second gear 140, the second actuator portion 176 is urged toward the second gear 140 by its own weight without providing the second urging member 180b. May be.

  Specifically, the first actuator portion 171 is formed in a substantially L shape that opens at an obtuse angle when viewed from the side (see FIG. 4A), and the bent portion 171a is pivotally supported. The first actuator portion 171 has a bent portion 171a as a center, one side being a first cam portion side 171b, and the other side being a first sensor portion side 171c. A first facing portion 174 is provided at the tip of the first cam portion side 171b, and a first detected portion 172 is provided at the tip of the first sensor portion side 171c. Similarly, the second actuator portion 176 is formed in a substantially L shape that opens at an obtuse angle when viewed from the side (see FIG. 4A), and a bent portion 176a is pivotally supported. The second actuator part 176 has a bent part 176a as a center, one side being a second cam part side 176b, and the other side being a second sensor part side 176c. A second facing portion 175 is provided at the tip of the second cam portion side 176b, and a second detected portion 177 is provided at the tip of the second sensor portion side 176c. Here, the first actuator unit 171 and the second actuator unit 176 are common components.

  In addition, the first and second urging members 180a and 180b are, here, winding springs. The first urging member 180 a is connected so that one end 181 a is urged toward the side plate 101 of the driving device 100 a and the other end 182 a is urged toward the first sensor portion 171 c toward the first gear 130. ing. The second urging member 180b is connected such that one end 181b is urged to the side plate 101 of the driving device 100a and the other end 182b is urged to the sensor unit side 176c to urge the second actuator unit 176 toward the second gear 140. .

  In the first embodiment, the first and second cam portions 131 and 141 are first and second convex portions, but may be first and second concave portions. In this case, the detection sensor 170 can be arranged on the opposite side (here, the upper side) with the first actuator part 171 and the second actuator part 176 placed.

  In the first embodiment, the first rotation angle θ1 is larger than the second rotation angle θ2, and the first detection time t1 is longer than the second detection time t2, but the first rotation angle θ1 may be smaller than the second rotation angle θ2, and the first detection time t1 may be shorter than the second detection time t2.

  In the first embodiment, the first gear 130 is provided coaxially with the photoconductor 3a in the first group photoconductor 30a. The second gear 140 is provided coaxially with the photoconductor 3b in the second group photoconductor 30b. Thus, detection by the gears 130 and 140 provided coaxially with the photoconductors 3a and 3b can reduce the rotation error between the photoconductors 3a and 3b and the gears 130 and 140, and the phase can be accurately detected. Can be combined.

(Second Embodiment)
Next, a driving device 100b according to another embodiment (second embodiment) of the first embodiment shown in FIG. 4 will be described. FIG. 6 is a diagram for explaining the second embodiment. FIG. 6A shows a schematic side view thereof. FIG. 6B shows a schematic bottom view thereof. FIG. 6C shows a schematic cross-sectional view along the line A1-A1 in FIG. FIG.6 (d) has shown schematic sectional drawing along the A2-A2 line | wire in Fig.6 (a). In FIG. 6, components that are substantially the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the second embodiment, a first gear 130a and a second gear 140a are provided instead of the first gear 130 and the second gear 140 of the first embodiment.

  The position of the first gear 131 in the rotation axis direction X of the first gear 130a is different from the position of the second gear 140a in the rotation axis direction X of the second cam 141. Specifically, the first gear 130a is provided with a first cam portion 131 on one side (here, the outside) in the rotation axis direction X, and the second gear 140a has a second cam portion 141 in the rotation axis direction. It is provided on the other side (here, the inside) of X. In addition to the first cam portion 131, the first gear 130a includes a second cam portion 141 provided on the second gear 140a when the first gear 130a is the second gear 140a. Is provided on the other side (inner side here). In addition to the second cam portion 141, the second gear 140a includes a first cam portion 131 provided on the first gear 130a when the second gear 140a is the first gear 130a. It is provided on the side (here, the outside).

  The first actuator portion 171 is provided such that the first facing portion 174 faces the first cam portion 131 of the first gear 130, and the second actuator portion 176 has the second facing portion 175 having the second facing portion 175. It is provided so as to face the second cam portion 141 of the gear 140.

  By doing so, it is possible to realize the common parts of the first gear 130a and the second gear 140a, thereby making it possible to easily match the rotation unevenness periods of the group photoconductors 30a and 30b. Parts costs can be kept low.

  In the first embodiment and the second embodiment, gears are used as the first and second rotating members 150 and 160, but existing members such as the flanges of the photoreceptors 3a and 3b, coupling members, and pulleys may be used. Good. Further, a disc may be provided separately, and this may be used as the first and second rotating members 150 and 160. FIG. 7 shows the state of the first and second rotating members 150 and 160 which are discs provided coaxially with the photoreceptors 3a and 3b.

(Rotational phase operation control)
Next, an example of operation for detecting the rotational phase Tr of the first group photoconductor 30a and the second group photoconductor 30b in the driving devices 100a and 100b of the first and second embodiments and adjusting the rotational phase Tr to the reference rotational phase will be described. explain.

  FIG. 8 is a control block diagram showing a system configuration for operating the driving devices 100a and 100b of the first and second embodiments.

  As illustrated in FIG. 8, the drive devices 100 a and 100 b further include a drive control unit 200 and a storage unit 300 that stores information from the drive control unit 200.

  The detection sensor 170 is connected to the input system of the drive control unit 200. The first drive unit 110 and the second drive unit 120 are connected to the output system of the drive control unit 200.

  As described above, the first drive unit 110 is a motor that drives the black photoconductor 3a and the black development unit 2a of the first group photoconductor 30a. The second drive unit 120 is a motor that drives the color photoconductors 3b, 3b, 3d and the color developing units 2b, 2c, 2d of the second group photoconductor 30b.

  The drive control unit 200 includes a microcomputer including a processing unit such as a CPU (Central Processing Unit) and a storage unit including a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory). Specifically, the drive control unit 200 performs drive control of various components by causing the processing unit to load and execute a control program stored in the ROM of the storage unit on the RAM of the storage unit. It is like that. The drive control unit 200 is instructed by a main control unit that controls the entire image forming operation provided in the image forming apparatus D.

  Specifically, the drive devices 100 a and 100 b further include a first drive unit drive control circuit 210 and a second drive unit drive control circuit 220.

  The first drive unit drive control circuit 210 is connected between the drive control unit 200 and the first drive unit 110. The second drive unit drive control circuit 220 is connected between the drive control unit 200 and the second drive unit 120.

  The drive control unit 200 gives commands to start and stop the first drive unit 110 to the first drive unit drive control circuit 210. The first drive unit drive control circuit 210 is a circuit that controls the start, stop, and drive speed of the first drive unit 110 under the instruction of the drive control unit 200, and here, the target commanded from the drive control unit 200 The servo control circuit controls the speed so that the driving speed of the first driving unit 110 matches the speed. The drive control unit 200 instructs the first drive unit drive control circuit 210 to drive the first drive unit 110 at a predetermined process speed (image formation drive speed) during image formation. ing.

  In addition, the drive control unit 200 gives commands to start and stop the second drive unit 120 to the second drive unit drive control circuit 220. The second drive unit drive control circuit 220 is a circuit that controls the start, stop, and drive speed of the second drive unit 120 under the instruction of the drive control unit 200. Here, the target commanded from the drive control unit 200 is used. The servo control circuit controls the speed so that the driving speed of the second driving unit 120 matches the speed. The drive control unit 200 instructs the second drive unit drive control circuit 220 to drive the second drive unit 120 at the process speed during image formation.

  The storage means 300 stores a reference rotation phase, which will be described later, and is a non-volatile memory in which data can be rewritten here.

  Note that the image forming apparatus D may include the drive control unit 200, the storage unit 300, and the first and second drive unit drive control circuits 210 and 220. Further, the storage unit 300 may be provided in the drive control unit 200.

  Incidentally, in the first group photoconductor 30a and the second group photoconductor 30b, the eccentricity of the photoconductor drums 3a to 3d and the rotation drive from the first drive unit 110 or the second drive unit 120 to the photoconductor drums 3a to 3d are performed. Rotation unevenness may occur due to eccentricity of the drive transmission rotating member (for example, the first gear 130, 130a or the second gear 140, 140a). Then, a phase shift (color shift) due to rotation unevenness due to eccentricity or the like between the black image formed by the first group photoconductor 30a and the color image formed by the second group photoconductor 30b may occur. is there.

  FIG. 9 is a diagram for explaining the phase shift of the rotation unevenness of the first group photoconductor 30a and the second group photoconductor 30b. In FIG. 9A, the period γ1 indicating the displacement state of the rotation unevenness generated in the first group photoconductor 30a is shifted from the period γ2 indicating the displacement state of the rotation unevenness generated in the second group photoconductor 30b. It is a graph which shows the state which is. FIG. 9B is a diagram illustrating an output signal from the detection sensor when the rotational phase Tr is adjusted to the reference rotational phase Ts. FIG. 9C is a graph showing the period when the rotational phase Tr is adjusted to the reference rotational phase Ts.

  As shown in FIG. 9A, when a shift γ3 occurs between the period γ1 of the first group photoconductor 30a and the period γ2 of the second group photoconductor 30b, the first group photoconductor 30a is formed. Image misalignment (color misregistration) between the black image and the color image formed by the second group photoconductor 30b is likely to occur.

  For this reason, the drive control unit 200 functions as means including phase adjustment means P1, phase detection means P2, phase difference detection means P3, and rotation phase correction means P4.

  In the phase adjusting means P1, as shown in FIG. 9B, a reference rotation phase Ts (Ts1 or Ts1) based on the rotation phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b. Adjust to Ts2).

  By doing so, as shown in FIG. 9C, the period γ1 in the first group photoconductor 30a and the period γ2 in the second group photoconductor 30b are prevented from shifting as much as possible. In this way, it is possible to suppress rotation unevenness due to eccentricity or the like, and consequently image shift (color shift).

  Specifically, in the phase adjusting means P1, a first phase adjusting (here, black adjusting) toner image is formed on the intermediate transfer belt 7 by the first group photoconductor 30a, and an intermediate is formed by the second group photoconductor 30b. A second phase adjusting (here, color adjusting) toner image is formed on the transfer belt 7, and based on these phase adjusting toner images, the rotational phase Tr of the first group photoconductor 30a and the second group photoconductor 30b. A reference rotation phase Ts (Ts1 or Ts2) in which (Tr1 or Tr2) is the optimum rotation phase is obtained, and at least one of the first drive unit 110 and the second drive unit 120 is set to the obtained reference rotation phase Ts. To adjust at least one of the rotation timing of the first group photoconductor 30a and the rotation timing of the second group photoconductor 30b.

  Note that the phase adjusting means P1 can be executed at the time of initial driving such as when the power is turned on and / or every predetermined period.

  However, even if the rotational phase Tr of the first group photoconductor 30a and the second group photoconductor 30b is matched to the reference rotational phase Ts as described above, the rotational phase Tr may be shifted.

  FIG. 10 is a diagram for explaining the operation control of the rotational phase. FIG. 10A shows an output signal from the detection sensor 170 when the rotation phase Tr is adjusted to the reference rotation phase Ts, and FIG. 10B shows the detection state. FIG. 10C shows an output signal from the detection sensor 170 when the rotation phase Tr deviates from the reference rotation phase Ts, and FIG. 10D shows the detection state. FIG. 10 shows the configuration of the first embodiment.

  As shown in FIGS. 10A and 10B, even if the rotational phase Tr of the first group photoconductor 30a and the second group photoconductor 30b is matched with the reference rotational phase Ts, the first group photosensitivity is obtained. When only one of the photoconductor 30a and the second group photoconductor 30b is driven to form an image, the rotational phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b is a reference. The rotational phase Ts (Ts1 or Ts2) is completely different from the rotational phase Ts (Tr1 or Tr2) of the first group photoconductor 30a and the second group photoconductor 30b in accordance with the printing operation. A deviation from Ts1 or Ts2) may occur (see FIG. 10C and FIG. 10D). As a result, image irregularity (color misregistration) due to uneven rotation due to eccentricity or the like may occur.

  Therefore, in the phase detection means P2, based on the first detection time t1 and the second detection time t2 by the detection sensor 170, the rotational phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b is determined. To detect.

  When the phase detection means P2 detects the rotational phase Tr1 between the first group photoconductor 30a and the second group photoconductor 30b, the detection start st (here, the first detection time t1 of the first group photoconductor 30a) From the rise of the output signal from the detection sensor 170 due to the sliding of the first facing portion 174 with the first cam portion 131), the detection start st (here, the second detection time t2) of the second group photoconductor 30b. The detection is performed by obtaining the phase time until the output signal from the detection sensor 170 rises due to the sliding of the facing portion 175 with the second cam portion 141.

  When the rotational phase Tr2 between the first group photoconductor 30a and the second group photoconductor 30b is detected, the detection end ed of the first detection time t1 of the first group photoconductor 30a (here, the first opposing portion) The detection end ed of the second detection time t2 of the second group photoconductor 30b ed (here, the second facing portion 175) from the fall of the output signal from the detection sensor 170 due to sliding with the first cam portion 131 of 174. The phase time until the output signal from the detection sensor 170 falls due to sliding with the second cam portion 141 is detected.

  By doing so, the rotational phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b can be detected with a relatively simple control configuration.

  It is preferable that the phase detection unit P2 detects the rotational phase Tr during the printing operation. By doing so, it is not necessary to separately drive the first group photoconductor 30a and the second group photoconductor 30b in order to detect the rotation phase Tr, and the rotation phase Tr can be detected more efficiently. .

  Further, in the phase difference detection means P3, the rotation phase difference (the rotation phase Tr (Tr1 or Tr2) detected by the phase detection means P2 with respect to the reference rotation phase Ts (Ts1 or Ts2) adjusted by the phase adjustment means P1 ( Deviation amount) Td (see FIG. 10C) is detected.

  Specifically, the rotational phase difference (deviation amount) Td is detected by obtaining a difference between the reference rotational phase Ts adjusted by the phase adjusting means P1 and the rotational phase Tr detected by the phase detecting means P2.

  Then, the rotational phase correction means P4 changes at least one of the rotation timing of the first group photoconductor 30a and the rotation timing of the second group photoconductor 30b based on the detection result by the phase difference detection means P3 to change the first group photosensitivity. The rotational phase Tr (Tr1 or Tr2) is corrected so that the rotational phase Tr (Tr1 or Tr2) between the body 30a and the second group photoconductor 30b becomes the reference rotational phase Ts (Ts1 or Ts2).

  Specifically, when it is determined that the rotation timing of the second gear 140, 140a is earlier (or later) than the first gear 130, 130a due to the difference between the reference rotation phase Ts and the rotation phase Tr, The first drive unit 110 and the second drive unit are configured such that the reference rotation phase Ts and the rotation phase Tr coincide with each other by delaying (or speeding up) the rotation timing of the second gear 140, 140a with respect to the first gear 130, 130a. At least one of 120 is controlled.

  By doing so, the rotational phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b can be adjusted to the reference rotational phase Ts (Ts1 or Ts2), thereby causing eccentricity or the like. It is possible to reduce the image shift (color shift) due to the rotation unevenness caused by.

  By the way, only one of the first group photoconductor 30a and the second group photoconductor 30b is driven, and the rotation phase Tr of the first group photoconductor 30a and the second group photoconductor 30b becomes the reference rotation phase Ts. Depending on the rotational position Tr of the first group photoconductor 30a and the second group photoconductor 30b, for example, when the second detection time t2 is greater than the first detection time t1, The whole or part of the first detection time t1 may overlap with the second detection time t2. In addition, when the first detection time t1 is longer than the second detection time t2, the whole or part of the second detection time t2 may overlap with the first detection time t1. Then, there is only one place where the detection start st and the detection end ed by the detection sensor 170 exist.

  FIG. 11 shows an output signal for explaining a state where there is only one detection start st and detection end ed by the detection sensor 170. FIG. 11A shows a state in which a part of the first detection time t1 and the second detection time t2 overlap, and FIG. 11B shows that the entire second detection time t2 is the first detection time. A state overlapping t1 is shown. In FIG. 11, the solid line indicates the first detection time t1, and the broken line indicates the second detection time t2.

  The detection start st and the detection end ed by the detection sensor 170 exist only at one place as shown in FIGS. 11 (a) and 11 (b).

  From this point of view, when the phase detection unit P2 determines that there is only one detection start st by the detection sensor 170, the phase detection unit P2 controls at least one of the first drive unit 110 and the second drive unit 120 to control the first. After rotating at least one of the first group photoconductor 30a and the second group photoconductor 30b so that the detection start st by the detection sensor 170 becomes two places, the phase time tr is measured, or the detection sensor 170 If it is determined that there is only one detection end ed, at least one of the first driving unit 110 and the second driving unit 120 is controlled, and the first group photoconductor 30a and the second group photoconductor 30b are controlled. After rotating at least one of the detection sensors 170 so that detection ends ed are at two places, the phase time tr is measured. By so doing, it is possible to reliably detect the rotational phase Tr (Tr1 or Tr2) between the first group photoconductor 30a and the second group photoconductor 30b.

  Further, it is preferable that the reference rotation phase Ts (Ts1 or Ts2) adjusted by the phase adjusting unit P1 is stored in the storage unit 300 in advance. In this case, the phase difference detection means P3 detects the rotation phase difference of the rotation phase Tr (Tr1 or Tr2) detected by the phase detection means P2 with respect to the reference rotation phase Ts (Ts1 or Ts2) stored in the storage means 300. To do. In this way, for example, if the reference rotation phase Ts (Ts1 or Ts2) is adjusted by the phase adjustment unit P1 at the time of initial driving and / or every predetermined period, and stored in the storage unit 300 at that time, it is useless. Thus, the adjustment operation by the phase adjusting means can be omitted, and the operation control time can be shortened accordingly.

  In the present embodiment, the first detection information and the first detection information 170 are recognized so that the single detection sensor 170 can recognize the difference between the rotation timing of the first group photoconductor 30a and the rotation timing of the second group photoconductor 30b. However, the first detection information and the second detection information detected by the single detection sensor 170 may be the same.

  In this case, when changing the rotational position Tr of at least one of the first group photoconductor 30a and the second group photoconductor 30b (for example, increasing the speed of one of the group photoconductors, or When the rotation phase Tr is separated from the reference rotation phase Ts after confirming whether or not the rotation phase Tr is separated from the reference rotation phase Ts. Changing the rotation position Tr of the group photoconductors is reversed (for example, when the speed of any group photoconductor is increased, the speed is decreased, or when the speed is decreased, the speed is increased). preferable.

3a to 3d Photosensitive drum (an example of an image carrier)
30a First group photoconductor (an example of a first group image carrier)
30b Second group photoconductor (an example of a second group image carrier)
110 1st drive part 120 2nd drive part 130,130a 1st gear (an example of a 1st rotation member)
131 1st cam part 131a Ascending slope part 131b Downhill slope part 140,140a 2nd gear (an example of a 2nd rotation member)
141 2nd cam part 141a Ascending inclination part 141b Downward inclination part 150 1st rotation member 160 2nd rotation member 170 Detection sensor 171 1st actuator part 172 1st to-be-detected part 173 Sensor part 173a Light emission part 173b Light reception part 174 1st opposing Part 175 second facing part 176 second actuator part 177 second detected part 180a first biasing member 180b second biasing member 300 storage means t1 first detection time (an example of first detection information)
t2 Second detection time (an example of second detection information)
D image forming apparatus P1 phase adjustment means P2 phase detection means P3 phase difference detection means P4 rotation phase correction means Q1 first pivot axis Q2 second pivot axis Td rotation phase difference Tr rotation phase Ts reference rotation phase X rotation axis direction α1 Outer peripheral surface (first outer peripheral surface)
α2 outer peripheral surface (second outer peripheral surface)
β1 first detection position β2 second detection position θ1 first rotation angle θ2 second rotation angle

Claims (21)

An image forming apparatus that forms a plurality of images using a plurality of image carriers respectively corresponding to the plurality of images, and superimposes the plurality of images,
A first group image carrier to which at least one of the plurality of image carriers belongs;
A second group image carrier to which at least one of the remaining image carriers belongs;
A first drive unit for rotationally driving the first group image carrier;
A second drive unit for rotationally driving the second group image carrier;
A first rotating member that rotates as the first group image carrier is rotated by the first driving unit;
A second rotating member that rotates as the second group image carrier is rotated by the second driving unit;
A single detection unit that detects first detection information for recognizing the rotation timing of the first group image carrier and detects second detection information for recognizing the rotation timing of the second group image carrier. A detection sensor and
On the outer peripheral surface of the first rotating member, a first cam portion is provided in at least part of the rotational axis direction and part of the circumferential direction,
On the outer peripheral surface of the second rotating member, a second cam portion is provided in at least part of the rotational axis direction and part of the circumferential direction,
The detection sensor detects rotation timing detection information by the first cam portion of the first rotation member as the first detection information, and the second cam of the second rotation member as the second detection information. An image forming apparatus configured to detect detection information of rotation timing by a unit. The image forming apparatus according to claim 1,
The first rotating member and the second rotating member have rotation axes parallel to each other,
The detection sensor includes a first actuator unit movable along a direction intersecting a rotation axis direction of the first rotating member, a first detected unit provided in the first actuator unit, and the second rotation. A second actuator unit movable along a direction intersecting the rotation axis direction of the member; a second detected unit provided in the second actuator unit; the first detected unit; and the second detected unit And a sensor unit for detecting
The first actuator portion is provided with a first facing portion facing the outer peripheral surface of the first rotating member,
The second actuator portion is provided with a second facing portion facing the outer peripheral surface of the second rotating member,
The first facing part and the first cam part are formed such that the sensor part detects the first detection information by the movement of the first detected part accompanying the movement of the first actuator part.
The second facing part and the second cam part are formed such that the sensor part detects the second detection information by the movement of the second detected part accompanying the movement of the second actuator part. An image forming apparatus. The image forming apparatus according to claim 2,
The first actuator portion is swingable about a first pivot shaft along the rotation axis direction, and the first cam portion rotates and moves with the rotation of the first rotation member. The first detected portion swings by swinging the first facing portion,
The second actuator portion is swingable about a second pivot shaft along the rotation axis direction, and the second cam portion rotates and moves with the rotation of the second rotation member. 2. The image forming apparatus according to claim 1, wherein the second detected portion swings when the second facing portion swings. The image forming apparatus according to claim 2 or 3, wherein
A first urging member that urges the first actuator portion toward the first gear; and a second urging member that urges the second actuator portion toward the second gear. An image forming apparatus. An image forming apparatus according to any one of claims 2 to 4, wherein
The sensor unit includes a light emitting unit and a light receiving unit, and incident light incident on the light receiving unit from the light emitting unit is detected by the movement of the first detected unit accompanying the movement of the first actuator unit. And the incident light incident on the light receiving unit from the light emitting unit is blocked by the second detected unit by the movement of the second detected unit accompanying the movement of the second actuator unit. An image forming apparatus, wherein the image forming apparatus is an optical sensor that detects the presence or absence of the incident light by the light receiving unit. An image forming apparatus according to any one of claims 1 to 5, wherein
The image forming apparatus according to claim 1, wherein the first cam portion of the first rotating member and the second cam portion of the second rotating member have the same circumferential length. An image forming apparatus according to any one of claims 1 to 5, wherein
The image forming apparatus according to claim 1, wherein the first cam portion of the first rotating member and the second cam portion of the second rotating member have different circumferential lengths. The image forming apparatus according to claim 7,
In addition to the first cam portion, the first rotating member is provided with the second cam portion provided on the second rotating member when the first rotating member is the second rotating member. In addition to the second cam portion, the second rotating member is provided with the first cam portion provided on the first rotating member when the second rotating member is the first rotating member. An image forming apparatus. An image forming apparatus according to any one of claims 1 to 8,
At least one of the first rotating member and the second rotating member is a rotating member provided coaxially with an image carrier in a corresponding group image carrier. An image forming apparatus according to any one of claims 1 to 9, wherein
The image forming apparatus, wherein the first rotating member is a gear or a pulley, and the second rotating member is a gear or a pulley. An image forming apparatus according to any one of claims 1 to 10, wherein
Each of the first cam part and the second cam part has an ascending slope part and a descending slope part. The image forming apparatus according to claim 11,
An image forming apparatus characterized in that a plane portion along the outer peripheral surface is formed between the climbing slope portion and the descending slope portion. An image forming apparatus according to any one of claims 1 to 12,
Phase adjusting means for adjusting the rotational phase of the first group image carrier and the second group image carrier to a reference rotational phase as a reference;
Phase detection means for detecting a rotational phase of the first group image carrier and the second group image carrier based on the first detection information and the second detection information by the detection sensor;
A phase difference detecting means for detecting a rotational phase difference of the rotational phase detected by the phase detecting means with respect to the reference rotational phase adjusted by the phase adjusting means;
Based on the detection result of the phase difference detection means, at least one of the rotation timing of the first group image carrier and the rotation timing of the second group image carrier is changed to change the first group image carrier and the second group image carrier. An image forming apparatus comprising: a rotation phase correcting unit that corrects a rotation phase with the group image carrier. The image forming apparatus according to claim 13,
Of the first group image carrier and the second group image carrier, the rotational position of at least one of the group image carriers is changed to check whether the rotational phase is separated from the reference rotational phase. With confirmation means,
The phase adjusting means and the rotational phase correcting means are the confirmation means when changing the rotational position of at least one of the first group image carrier and the second group image carrier. After confirming whether or not the rotational phase is away from the reference rotational phase, if the rotational phase is away from the reference rotational phase, the rotational position of the at least one group image carrier An image forming apparatus characterized by reversing the change of the above. The image forming apparatus according to claim 13 or 14,
The phase detection means measures a phase time between the detection start of the first detection information by the detection sensor and the detection start of the second detection information by the detection sensor, or the phase detection means by the detection sensor. An image forming apparatus that measures a phase time between the end of detection of one detection information and the end of detection of the second detection information by the detection sensor. The image forming apparatus according to claim 15, wherein
When there is only one detection start by the detection sensor, the phase detection unit detects that at least one of the first group image carrier and the second group image carrier is not detected by the detection sensor. The phase time is measured after being rotated so that it becomes a place, or when there is only one place where detection by the detection sensor ends, the first group image carrier and the second group image carrier An image forming apparatus, wherein the phase time is measured after rotating at least one of the bodies so that detection by the detection sensor ends at two places. An image forming apparatus according to any one of claims 13 to 16, comprising:
The reference rotation phase adjusted by the phase adjustment unit is stored in advance in a storage unit,
The image forming apparatus, wherein the phase difference detection unit detects a rotation phase difference of a rotation phase detected by the phase detection unit with respect to the reference rotation phase stored in the storage unit. An image forming apparatus according to any one of claims 13 to 17,
The rotational phase correction unit drives at least one of the first drive unit and the second drive unit based on a detection result by the phase difference detection unit, so that the rotational timing of the first group image carrier and the An image forming apparatus, wherein at least one of rotation timings of the second group image carrier is changed to correct a rotation phase between the first group image carrier and the second group image carrier. The image forming apparatus according to any one of claims 13 to 18, comprising:
The image forming apparatus, wherein the phase detection unit detects the rotational phase during a printing operation. An image forming apparatus according to any one of claims 1 to 19,
The first group image carrier is for performing monochrome image formation,
The image forming apparatus according to claim 1, wherein the second group image carrier is for forming a color image in cooperation with the first group image carrier. A drive device provided in an image forming apparatus that forms a plurality of images using a plurality of image carriers respectively corresponding to the plurality of images, and superimposes the plurality of images,
A first driving unit for rotationally driving a first group image carrier to which at least one of the plurality of image carriers belongs;
A second driving unit for rotationally driving a second group image carrier to which at least one of the remaining image carriers belongs,
A first rotating member that rotates as the first group image carrier is rotated by the first driving unit;
A second rotating member that rotates as the second group image carrier is rotated by the second driving unit;
Detection information on the rotation timing of the first rotating member is detected as first detection information for recognizing the rotation timing of the first group image carrier, and the rotation timing of the second group image carrier is recognized. And a single detection sensor for detecting detection information of rotation timing of the second rotating member as second detection information for
On the outer peripheral surface of the first rotating member, a first cam portion is provided in at least part of the rotational axis direction and part of the circumferential direction,
On the outer peripheral surface of the second rotating member, a second cam portion is provided in at least part of the rotational axis direction and part of the circumferential direction,
The detection sensor detects rotation timing detection information by the first cam portion of the first rotation member as the first detection information, and the second cam of the second rotation member as the second detection information. A drive device configured to detect detection information of rotation timing by a unit.

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