JP4993701B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a phase adjusting means composed of a smaller number of components than heretofore in an image forming apparatus having a plurality of photoreceptors driven by a single drive source and a transfer body to which the images of the photoreceptors are transferred. <P>SOLUTION: The phase adjusting means has a photoreceptor driving gear (driving) 5 and a photoreceptor driven gear (to be driven) 4 provided with a pair of recessed and projecting shaped parts 9 and 11 meshed with each other. The gears have the different recessed and projecting shapes 10 and 12 of the recessed and projecting shaped parts for every photoreceptor, and driving force is transmitted to the photoreceptor by meshing of the recessed and projecting shapes. When driving of the driving source, reverse rotation and normal rotation are repeated in a rotating direction, whereby the meshing position between the recessed and projecting shapes is deviated to adjust phase relation in the speed variation of each photoreceptor. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine.

  In a so-called electrostatic color image forming apparatus that has a plurality of photoconductors that form toner images of different colors and obtains a color image by superimposing and transferring the images on the photoconductors, the speed variation of each photoconductor In order to reduce color misregistration caused by equal phase shift, a method of driving one photoconductor with one drive source, adjusting the rotation phase based on the mark of the gear, and adjusting the rotation speed of the photoconductor Control techniques are well known. However, in this method, for example, four driving sources are required to drive four photosensitive members, and a lot of space is also required.

  Therefore, a method of driving a plurality of photoconductors with a single drive source has been proposed (see, for example, Patent Document 1). This drive configuration includes a plurality of photosensitive drums, a drive motor for rotationally driving the plurality of photosensitive drums, and a gear train for transmitting a driving force from the drive motor to the plurality of photosensitive drums. In an image forming apparatus in which a photosensitive drum is rotationally driven by a gear train from a drive motor at the same period, a phase at the time of rotation of at least one of the plurality of photosensitive drums to which the gear train transmits driving force is determined. And a phase displacement means for displacing with respect to the phase when the other photosensitive drums are stopped.

  This phase transmission means is a clutch means for cutting and connecting the transmission of the driving force, and a delay means for delaying the transmission of the driving force. However, in this method, the number of parts is increased by using clutch means and delay means which are independent parts.

  Even in the case of using an inclined gear and a cam as the shaft phase adjusting means (see, for example, Patent Document 2), the number of parts is increased in that the inclined gear and the cam, which are independent parts, are similarly used.

JP 2005-157169 A JP 2006-106591 A

  An object of the present invention is to realize a phase adjusting means having a configuration with a smaller number of parts than in the past.

In order to achieve the above object, an invention according to claim 1 is directed to image formation comprising a plurality of photoconductors coupled so as to be driven by a single drive source, and a transfer body onto which images of these photoconductors are transferred. In the device
A photosensitive member driving gear (driving) and a photosensitive member driving gear (driven) which are disposed adjacent to each other on the same axis and are provided with a pair of concavo-convex shape portions which can mesh with each other on the opposite side surface portions;
The concavo-convex shape portion includes a plurality of concavo-convex portions formed along the circumference of a circle centered on the axis, and the ridge portion is formed on the photosensitive member driving gear (covered) when the photosensitive member driving gear (driving) rotates in one direction. The photosensitive member driving gear (driving) rotates in a direction opposite to the one direction with respect to the photosensitive member driving gear (driven) while meshing with the abutting surface that contacts the convex portion of the driving) and transmits the power. It has a mountain shape formed with a slide surface that allows
These gears are configured such that the interval between the plurality of convex portions is different for each driven photosensitive member, and the driving force is transmitted to the photosensitive member by meshing of the concavo-convex shapes,
When the driving source is driven, the rotational direction is repeatedly reversed and forward rotation, thereby shifting the meshing positions of the concavo-convex shapes and adjusting the phase relationship of the speed fluctuation of each photoconductor.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus includes a reading unit for reading an image pattern drawn on the transfer body, and the drive source is driven and controlled according to the reading result. and was a Rukoto adjust the phase shift of the speed fluctuation of the plurality of the photosensitive members.
The invention according to claim 3 is the image forming apparatus according to claim 1 or 2 ,
Said abutment surface consists of a plane parallel to the axial direction, the sliding surface was Rukoto such from the inclined surface intersecting with the axial direction.
An invention according to claim 4 is the image forming apparatus according to any one of claims 1 to 3,
Was Rukoto to pressurize the direction of approaching by the irregularities pressurizing the two photoconductor driving gear together drivingly connected with part pressure body.
The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4,
With helical gear on the drive side of the gear that is drivingly connected by concave-convex part, the two gears was Rukoto is set the direction twisted so that force acts in the direction approaching the normal rotation of the gear.
The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 5,
The gear portion and the concavo-convex shape portion are separated and integrally configured .
The invention according to claim 7 is the image forming apparatus according to any one of claims 1 to 6 ,
A DC motor having a brake function is used as the drive source .
The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 6 ,
A stepping motor is used as the drive source. The invention according to claim 9 is the image forming apparatus according to any one of claims 1 to 8 ,
Of the two gears, a driving connection system using a gear is used for driving connection between the photosensitive member driving gear (driven) and the photosensitive member .
The invention according to claim 10 is the image forming apparatus according to any one of claims 1 to 8 ,
Of the two gears, a drive connection system using a joint is used for drive connection between the driven gear and the photosensitive member.
An invention according to claim 11 is the image forming apparatus according to any one of claims 1 to 8 ,
Instead of a single drive source, a plurality of drive sources are provided in which the drive source for the color image forming photoconductor and the monochrome image forming photoconductor is separated .
The invention according to claim 12 is the image forming apparatus according to claim 11 ,
Means are provided for detecting the rotational position of the photoreceptor .
The invention according to claim 13 is the image forming apparatus according to any one of claims 1 to 12,
The transfer member and the photosensitive member can be contacted and separated .
The invention according to claim 14 is the image forming apparatus according to any one of claims 1 to 13,
Means is provided for detecting the replacement timing of the photoconductor or a replaceable unit including the photoconductor.
The invention according to claim 15, in the image forming apparatus according to any one of claims 1 to 1 3,
Means for detecting the rotational speed of the photoconductor or a replaceable unit including the photoconductor is provided .

According to the invention described in claim 1, also in small drive arrangement of electrical components for driving a plurality of photosensitive bodies in one driving source, component by causing attached a concave and convex portion on the originally required gear as the drive system Without increasing the number of points, it is possible to match the phase of the speed fluctuation of the photoconductor as in the driving configuration in which one photoconductor is driven by one drive source, and color shift in the sub-scanning direction can be reduced.
According to the second aspect of the present invention, the phase including the phase of the speed fluctuation of the photoconductor caused by the phase shift due to the replacement of the photoconductor, the load fluctuation of the photoconductor, the deflection angle of the joint portion, and the like is included. it is possible to fit the.
According to the third aspect of the present invention, when the photosensitive member is driven reversely, the convex portion of the photosensitive member driving gear (driving) rides on and slides on the sliding portion of the photosensitive member driving gear (driven) to drive the photosensitive member. The gear (driven) does not rotate, and the phase can be shifted and phase adjustment can be performed by combining this amount and the rotation direction.
According to the fourth aspect of the present invention, by applying pressure to the photosensitive member driving gear (driven) in the thrust direction with the pressurizing member, the driving force after the protrusion on the slide portion is used to restore the original position. The relationship can be restored, and subsequent drive transmission is not hindered.
According to the fifth aspect of the present invention, it is possible to return to the original positional relationship by using the driving force after the protrusion on the slide portion without using the pressurizing means, which hinders the subsequent drive transmission. Do not come.
According to the sixth aspect of the present invention, it is possible to prevent large variations in the amount of eccentricity of the gear, and as a result, the effect of reducing color misregistration is increased.
According to the seventh aspect of the present invention, the accuracy of the gear stop position at the time of forward / reverse rotation is increased during implementation of the invention, and the phase alignment accuracy can be improved.
According to the eighth aspect of the present invention, the accuracy of the gear stop position at the time of forward / reverse rotation is increased during implementation of the invention, and the phase alignment accuracy can be improved.
According to the ninth aspect of the invention, the phase of the photoconductor gear can be easily matched, and the effect of reducing color misregistration can be obtained.
According to the invention of claim 1 0, it is possible to phase adjustment, including a phase shift generated in the joint portion.
According to the invention of claim 1 1, in addition to the effect of extending the life of the photoreceptor by the driving of the monochrome photoreceptor and the full photoreceptor to a different drive sources, the phase of the speed variation between the photoreceptor full color The effect of reducing color misregistration can be obtained by combining them.
According to the invention of claim 1 2, it is possible to match the phases of the speed variation between the black and white photosensitive member and the full photoreceptor, when the driving source of monochromatic photosensitive member and the color photosensitive material and common single The effect of reducing color misregistration is greater.
According to the invention described in claims 1 to 3, it is possible to prevent a decrease in life to avoid rubbing of the transfer member and the photosensitive member at the time of the phase adjustment performed.
According to the invention described in claims 1 to 4, by performing the phase adjustment in accordance with the replacement timing of the unit, it is possible to minimize the time of occurrence of downtime of the image forming apparatus.
According to the invention described in claim 15 , since it is possible to know the replacement time of the unit, it is possible to adjust the phase at a regular timing. As a result, the phase relationship is shifted in time due to the load variation of the photosensitive member. Even if there is a failure, it is possible to adjust to the optimal phase relationship periodically.

Hereinafter, an image forming apparatus to which the present invention is applied will be described.
Example 1: Configuration in which a plurality of photoconductors are driven by a single drive source In FIG. 1, photoconductors 1A, 1B, 1C, and 1D having the same diameter in the form of drums on which toner images of different colors are formed are belt-like. They are juxtaposed along the transfer body 2 with a gap. Photosensitive member gears 3 having substantially the same diameter as the photosensitive member are fixed to axial ends of the respective photosensitive members 1A, 1B, 1C, and 1D. Each photoconductor gear 3 is meshed with a photoconductor drive gear (driven) 4.

  In this manner, the photosensitive member driving gear (driven) 4 and the photosensitive member gear 3 are gear-connected, and the plurality of photosensitive members 1A to 1D are connected and driven by one motor that drives the driving gear 7. In this case, the meshing position of the photoconductor gear 3 and the photoconductor drive gear (driven) 4 varies when the photoconductor is replaced, so that phase alignment at the time of assembly of the main body drive is impossible. Therefore, in this example, the effect of reducing color misregistration can be obtained by matching the phase of the photoconductor gear.

  A photoconductor drive gear (drive) 5 is provided coaxially with each photoconductor drive gear (driven) 4, and the photoconductor drive gear (drive) 4 and the photoconductor drive gear (driven) 5 are these gears. The power is transmitted by the meshing of the concavo-convex portions provided respectively. As shown in FIG. 1, a power transmission gear 6 that meshes in common is provided between adjacent photosensitive member drive gears (drives) 5.

  In FIG. 1, any one of the four photosensitive member driving gears (drives) 5 can be rotated forward or backward to any one of the photosensitive member drive gears (drives) 5 belonging to the second photosensitive member 1B from the left in this example. A driving gear 7 as a driving source connected to a simple motor is meshed.

  With this configuration, when the driving gear 7 rotates, the power is transmitted in the order of the photosensitive member driving gear (driving) 5 → engagement of the convex and concave portions → the photosensitive member driving gear (driven) 4 → the photosensitive member gear 3 in order. The two photoconductors 1A, 1B, 1C, and 1D are rotationally driven in the same direction.

  The transfer member 2 is wound around a drive shaft 8 and a driven shaft 8 'arranged so as to have an axis parallel to the axis of the photosensitive member. A drive source of the drive shaft 8 for driving the transfer body 2 is not shown, but is a drive source different from the driving gear 7 for driving the photosensitive member.

  The photoconductors 1A, 1B, 1C, and 1D correspond to images of different colors. For example, the photoconductor 1A is black, the photoconductor 1B is magenta, the photoconductor 1C is cyan, and the photoconductor 1D is a yellow toner image. Supported.

  The configuration including the drive system around the photoconductor 1A is called station A, the same configuration around the photoconductor 1B is called station B, the same configuration around the photoconductor 1C is called station C, and the same configuration around the photoconductor 1A is called station D.

  Since each station has the same mechanical configuration, as a representative example, for station A, an uneven shape portion for connecting the photosensitive member driving gear (driven) 4 and the photosensitive member driving gear (driving) 5 according to FIG. The configuration will be described.

  In FIG. 2, the photosensitive member driving gear (driven) 4 and the photosensitive member driving gear (driving) 5 are disposed adjacent to each other on the same axis OO and can be engaged with each other on opposite side portions. It has a shape part.

  The concavo-convex shape portion 9 formed on the side surface of the photosensitive member driving gear (drive) 5 includes four concavo-convex portions formed at equal intervals along a virtual circle centered on the axis OO. The concave portion is relatively formed between adjacent convex portions.

  In FIG. 2, the side surface of the photosensitive member driving gear (driven) 4 facing the photosensitive member driving gear (driving) 5 cannot be seen due to the viewpoint, and therefore, the viewpoint is changed in FIG. In FIG. 3, the concavo-convex shape portion 11 formed on the side surface of the photosensitive member driving gear (driven) 4 is composed of four concavo-convex portions formed at equal intervals along a virtual circle centered on the axis OO. A recessed part is a recessed part formed relatively between adjacent convex parts.

  The concavo-convex shape portion 9 of the photosensitive member driving gear (driven) 4 and the concavo-convex shape portion 11 of the photosensitive member driving gear (driving) 5 are engaged with each other, or the engagement is released. Can be.

2 and 3, when attention is paid to any one convex portion 10 with respect to the photosensitive member driving gear (driving) 5, the convex portion 10 has the photosensitive member driving gear (driving) 5 in one direction (clockwise indicated by an arrow). The contact surface 10a that transmits power by contacting the convex portion 12 (specifically, the contact surface 12a) of the photosensitive member drive gear (driven) when rotating in the direction of the photosensitive member drive gear (drive). ) 5 has a chevron shape formed by an inclined slide surface 10b that allows the photoconductor drive gear (driven) 4 to rotate in the direction opposite to the one direction. Moreover, the chevron forming the convex portions 12 of the photosensitive body driving gear (driven) 4, wherein a contact surface 1 0a abutting abutment surface 12a, and the inclined slide surface 12b which slides with the sliding surface 10b It is formed with.

  As described above, since the contact surface parallel to the axial direction and the inclined surface intersecting the axial direction are provided, the contact surface ensures the power transmission during the forward rotation, and the inclined surface causes the uneven portion during the reverse rotation of the gear. As a result, the driven gear does not rotate during reverse rotation. By combining this amount and the direction of rotation, the phase can be shifted and phase adjustment can be performed.

FIG. 4 schematically shows the meshing state of the concavo-convex shape portion 9 including the convex portion 10 and the concavo-convex shape portion 11 including the convex portion 12. In this example, a photosensitive member driving gear (driving) 5 and a photosensitive member driving gear (driven) 4 are rotatably provided on the shaft 13. In order to secure the meshing state of the concave and convex portions, the photosensitive member driving gear (drive) 5 is configured to be pressed toward the photosensitive member driving gear (driven) 4 side by a pressure spring 14. That is, the two photoconductor driving gears that are driven and connected by the concavo-convex shape portion are pressed in the direction approaching by the pressing spring 14. The pressure applied by the pressure spring 14 reaches the photosensitive member driving gear (driven) 4 through the meshing portions of the concavo-convex portions 11 and 12, so that a stopper 6 is provided on the shaft 13 and the photosensitive member driving gear by the pressing spring 14 is provided. (Driven) 4 is prevented from shifting.
When shifting the phase by getting over an inclined slide surface, the gears are not connected during forward rotation if the gears are separated from each other. In this example, after the convex part 10 gets over the slide surface 12b, the structure pressurized with the pressurization spring 14 is used for the purpose of returning to the original connection state.

  When the driving gear 7 rotates in the forward direction under the meshing state shown in FIG. 4, the power from the drive transmission gear 6 is transmitted to the photosensitive member driving gear (drive) 5 and rotates in the direction of the arrow. 10a pushes and moves the contact portion 12a, the photosensitive member driving gear (driven) 4 is also rotated in the same direction, and the photosensitive member gear 3 and the photosensitive member 1A are rotated together.

  The photosensitive member drive gear (drive) 5 pressed by the pressure spring 14 is slidable in the axial direction. When the driving gear 7 is switched to reverse rotation, the photosensitive member driving gear (driving) 5 rotates in the direction opposite to the direction of the arrow. At this time, since the photosensitive member driving gear (driven) 4 is connected to the photosensitive member gear 3 having a rotational load, the photosensitive member driving gear (driven) 4 does not rotate and slides the concave and convex portion 9 with respect to the fixed concave and convex portion 11. The surface 10b slides on the slide surface 12b, rides on the slide surface 12b, and the meshing state can be automatically released. At this time, the photosensitive member drive gear (drive) 5 moves left on the shaft 13 against the elasticity of the pressure spring 14.

  Depending on the amount of reverse rotation, the photosensitive member drive gear (drive) 5 can be rotated to a position where the meshing position is shifted in the rotational direction with respect to the initial meshing position before the reverse rotation, and the driving gear 7 is rotated forward. By doing so, the contact surface 10a and the contact surface 12a are brought into contact with each other, and a normal meshing state is obtained at this shifted position.

  The same configuration as the uneven shape portion 9 and the uneven shape portion 11 in the station A is also provided in the other stations B, C, and D, but the uneven shapes are different for the stations A, B, C, and D, respectively. Shape.

A configuration of phase adjustment among the stations A, B, C, and D will be described.
FIG. 5 schematically illustrates the concavo-convex shape portion 11 for each of the stations A, B, C, and D developed for ¼ of one round. As shown in FIG. 5, the uneven shape is different for each of the stations A, B, C, and D. The intervals between the convex portions (concave portions) are different in each of the stations A, B, C, and D. Represents. In order to shift the phase between colors, it is necessary that the uneven shape is different for each color. For example, in FIG. 3, there are four convex portions 10 (or convex portions 12) in one circumference, and when this is applied to station A in FIG. 5, it is considered that there are four in station A, eight in B, and sixteen in C. That's fine. The same applies to the uneven portion 9.

  In order to actually adjust the phase, it is necessary to reverse the motor 5. When the driving gear 7 is reversely rotated by the motor, the driving gear 7 drives the photosensitive member driving gears (drives) 5, the photosensitive member driving gears (driving) 5 to the photosensitive member driving gears (driven) 4, and the photosensitive member driving gears ( The drive is transmitted from the (driven) 4 to each photoconductor gear 3. As described above, since the photoconductor gear 3 and the photoconductor drive gear (driven) 4 are subjected to a rotational load, the photoconductor gear 3 and the photoconductor drive gear (driven) 4 do not rotate unless a torque greater than the load is applied.

  Driving connection of the photosensitive member driving gear (driven) 4 and the photosensitive member driving gear (driving) 5 is performed by meshing the concavo-convex shape portions 9 and 10, and the convex portion 10 gets over the slide surface 12b during reverse rotation. Therefore, when the driving gear 7 (motor) is rotated in the reverse direction, the driving gear 7 and each photosensitive member driving gear (driving) 5 are rotated, and each photosensitive member gear 3 and the photosensitive member driving gear (driven) 4 are stopped. Keep state.

  As a result, at each of the stations A, B, C, and D, the convex portion 10 rides on the slide surface 12b of the photosensitive member driving gear (driven) 4 as the photosensitive member driving gear (driving) 5 rotates. It can rotate and shift its phase while moving in the axial direction against the elasticity of the pressure spring 14. In the case of “friction load on the slide surfaces 10b and 12b <load applied to the photoconductor gear 3 and the photoconductor drive gear (driven) 4”, the above operation is possible. During forward rotation of the driving gear 7, the concave and convex portions 9 and 11 are not in contact only with the slide surfaces 10b and 12b, but are also contacted with the contact surfaces 10a and 12a. It is possible to simply transmit the drive.

  A method for adjusting the phase will be described. FIG. 5 considers that the uneven | corrugated shaped part 11 which consists of the unevenness | corrugation arrange | positioned on the circle | round | yen expanded and showed on the straight line. The arrow pointing to the right is the reverse direction of the photosensitive member drive gear (drive) 5, and the arrow pointing to the left is the normal direction. As described above, the convex portion 12 of the photosensitive member driving gear (drive) 5 gets over the convex portion 12 of the photosensitive member driving gear (driven) 4 at the time of reverse rotation, and does not get over at the time of forward rotation.

  In each of the stations A, B, C, and D, for example, when the photosensitive member driving gear (drive) 5 is reversely rotated from the angle α at which the phases of the contact surfaces 12a are aligned to an arbitrary angle β, the photosensitive member The convex portion 10 of the drive gear (drive) 5 does not go over the adjacent convex portion 12b for the stations A and B, but is a position where the convex portion 10b passes over one convex portion 12b in the station A and two convex portions 12b in the station B. It is in. When the photosensitive member drive gear (drive) 5 is rotated forward from the state β, the stations A and B return to the position α, and the station C has one pitch for the convex portion 12 and the station D has two pitches for the convex portion 12. Will be out of phase only. In this example, since the distance of one pitch of the convex portion 12 for the station C is twice the distance of one pitch of the convex portion 12 for the station D, as a result of reverse rotation from α to β, “ The phase is shifted by an angle of (β−α) between “Stations A and B” and “Stations C and D”. At this time, the phases between the stations A and B and between the stations C and D are not changed. If the same method is used to reversely rotate from α to γ, for example, it is possible to provide a phase difference of (γ−α) between “station A” and “stations B, C, D”. .

In this way, when the motor (primary gear 7) as a driving source is driven, the photosensitive member driving gear (driving) 5 and the photosensitive member driving gear (driving) 5 are repeatedly rotated in the reverse direction and forward rotation. It is possible to adjust the phase relationship of the speed fluctuations of the respective photosensitive members by shifting the meshing positions of the concave and convex shapes of the body driving gear (driven) 4. According to this, it is also possible to reduce the color misregistration by providing a mark in advance on the gear of the photosensitive member driving system and adjusting the phase so that the mark is in phase. If the concave and convex portion 9 and the photosensitive member driving gear (drive) 5 and the concave and convex portion 10 and the photosensitive member driving gear (driven) 4 are integrated or substantially integrated, the number of parts does not increase.
Further, even in a drive configuration in which a plurality of photoconductors are driven by a single motor, the phase of the speed fluctuation of the photoconductor can be matched in the same manner as in a drive configuration in which a single photoconductor is driven by a single motor. This is possible, and color misregistration in the sub-scanning direction can be reduced.

Example 2: Configuration for controlling drive source according to image pattern reading result Using the configuration and method in Example 1 as they are, and further controlling the driving source according to the image pattern reading result, the phase of speed fluctuation of each photoconductor Adjust the deviation. As shown in FIG. 1, a detection means 15 that reads the image pattern is arranged facing the transfer body 2. As shown in FIG. 6, the test pattern 16 formed on the transfer body 2 by the respective photoreceptors 1A to 1D is read by the detection means 15, and the optimum phase position is calculated based on the waveform without causing color misregistration. , It can be adjusted to the optimum phase relationship.

  A control means (not shown) is adapted to input information from the detection means 15, and the reverse and correct rotation of the photosensitive member drive gear (drive) 5 necessary for matching the optimum phase relationship from the waveform of the read test pattern. The number of rotations, the amount of reverse rotation, and the like are calculated, and the motor that drives the driving gear 7 is instructed to execute the rotation.

  An example of the phase adjustment procedure in the control means will be described with reference to the flowchart shown in FIG. In this example, the phase of the rotational position is shifted between the photoconductors due to the replacement of the photoconductors. Therefore, in step P1, the phase adjustment is performed by detecting the replacement of the photoconductors with a sensor.

  In step P2, phase matching control is started. The test pattern 16 is formed on the transfer body 2 as described above in step P2-1. In step P2-2, the test pattern 16 is read by the detection means 15 and information is taken into the control means. In step P2-3, the phase difference from the optimum value is calculated using data stored in advance in the storage means. In Step P2-4, it is determined whether or not the phase difference from the optimum value is within the reference. If it is within the reference, the process ends. If the reference is not satisfied, the process proceeds to Step P2-5 to execute the phase adjustment.

  In Step P2-5, a measure for separating the photoreceptors 1A to 1D and the transfer body 2 in advance so that the photoreceptors 1A to 1D and the transfer body 2 are not rubbed with each other as the drive system is rotated forward and then rotated forward. do. As an example, in FIG. 5, when rotating forward from β to α during forward rotation, the photosensitive member 1 </ b> A does not rotate at the station A, but at the other stations B, C, and D, the transfer member 2 is stationary. On the other hand, since the photoconductors 1B, 1C, and 1D rotate, the photoconductor is protected from rubbing. In Step P2-6, the necessary amount and number of reverse and forward rotation operations are executed to bring the phase difference within the standard.

  In the present invention, as described in Example 1, a mark is provided in advance on the gear of the photosensitive member drive system, and phase adjustment is performed so that the phase of the mark is matched, so that the speed fluctuation of the photosensitive member caused by the eccentricity of the gear is detected. Color shift can be reduced by matching the phase. However, in this method, it is possible to match the phase of the eccentricity generated at the time of molding the gear, but it is not possible to match the phase of the speed fluctuation caused by factors other than the gear eccentricity. Further, since the phase of the photoconductor gear changes due to the change of the meshing position when the user is installed, even if the phase is adjusted during assembly, the phase changes every time the user replaces the photoconductor. In contrast, in this example, adjustment is performed based on the phase shift caused by replacement of the photoconductor and the test pattern, so the phase of the photoconductor speed fluctuation caused by the photoconductor load fluctuation and joint deflection angle is also included. In this state, the phase can be adjusted, and the effect of reducing color shift is further increased.

Example 3: Concave and convex portions of some stations do not have a sliding surface. When station A is used as a reference and the phases of other stations B, C, and D are aligned with station A, as shown in FIG. If the concavo-convex shape portions 9 and 11 at the station A are not provided with the slide surfaces 10b and 12b and are kept in the meshed state at the time of forward rotation and reverse rotation, only the station A has the photosensitive member driving gear (drive) 5 at the time of reverse rotation. Then, the photosensitive member driving gear (driven) 4 is rotated, and the phase is adjusted with reference to the station A.

  Whether the photoconductor 1A of the reference station A is rotated or not when the driving gear (motor) is reversed can be selected depending on whether or not the slide surface 10b is provided on the convex portion 10, and the former advantage is the phase of the reference Therefore, there is an advantage that the accuracy of phase adjustment is the same as that of the latter, and it is not necessary to make the shapes of the uneven portions 9 and 11 finer than the former. However, the former demerit is that the photoconductor rotates in the reverse direction, and the former cannot be used in the photoconductor that causes a problem in quality due to the reverse rotation. In any case, in order to adjust the phase, it is a necessary condition that the shapes of the concave and convex portions 9 and 11 are different for each station.

Example 4: Example of using Hasuba gear as pressurizing means As shown in FIG. 9, the photoreceptor driving gear (drive) 5 ′ (corresponding to the photoreceptor driving gear (drive) 5 in FIG. 4) is composed of a Hasuba gear. is doing. The same applies to the power transmission gear 6 'meshing with this (corresponding to the power transmission gear 6 in FIG. 4).
Due to the nature of the helical gear, a force acts in the thrust direction in addition to torque transmission in the rotational direction. By setting the twist direction so that the photosensitive member driving gear (driving) 5 ′ approaches the photosensitive member driving gear (driven) 4 during forward rotation, the photosensitive member driving gear (driven) 4 and the photosensitive member drive during forward rotation are set. The gear (drive) 5 ′ is in a drive connection state, and is in a non-drive connection state during reverse rotation. Thereafter, in the same manner as in the above-described method, the phase can be adjusted using forward rotation and reverse rotation by making the shapes of the uneven shape portion 9 ′ and the uneven shape portion 11 ′ different for each station. Even if the shape of the concavo-convex shape portion 9 ′ and the concavo-convex shape portion 11 ′ is a configuration that does not have a slide surface as in the above example (for example, a configuration as in the station A in FIG. 5), Since the driving gear (driven) 4 and the photosensitive member driving gear (driving) 5 ′ are separated from each other, the object can be achieved. A stopper is provided on the shaft 13 so that the photosensitive member driving gear (driving) 5 'is not displaced excessively. In this example, it is of course possible that the concavo-convex shape portion has a slide surface and a pressure spring is attached.

Example 5: The gear portion and the concavo-convex shape portion are formed separately and integrally formed. In the photoconductor drive gear (driven) 4, the photoconductor drive gear (drive) 5, 5 ′, etc., the gear portion and the concavo-convex shape portion 9 are provided. , 9 ′, 11, 11 ′, etc. are separated. In order to perform the phase adjustment, as described above, it is necessary that the shapes of the uneven portions 9, 9 ′, 11, 11 ′ differ for each station.

For example, when the photosensitive member drive gear (drive) 5 and the concavo-convex portion 9 are molded with the same mold, the eccentricity of the photosensitive member drive gear (drive) 5 varies from station to station, resulting in the speed of the photosensitive member. There is a fear that the amplitude of the fluctuation becomes large for each station. As shown in FIG. 10, even if the phase in the time axis direction is in phase as shown by the four curves formed by the photoconductors 1A to 1D, as the difference in the amplitude of the speed fluctuation increases, for example, When a shift Δ that causes a large color shift occurs on the photosensitive member, the effect of phase matching is reduced.
Therefore, for the photosensitive member driving gear (driven) 4 and the photosensitive member driving gears (driving) 5, 5 ′, the same parts are used in all stations, and only the concave and convex portions 9, 9 ′, 11, 11 ′ are used. The above problems are solved by combining them as separate members.

Example 6: Example of motor used as drive source With respect to the motor that drives the driving gear 7, accuracy of the stop position is required in order to perform phase adjustment with high accuracy. It is advantageous to increase the reduction ratio between the driving gear 7 and the photosensitive member driving gears (drives) 5 and 5 ′. In addition to the reduction ratio, the motor that drives the driving gear 7 is preferably a DC motor having a brake function instead of a simple DC motor. Since a DC motor that does not have a brake function simply cuts off drive transmission, there is a time delay from the stop command to the stop, and it is difficult to stop at the intended position. Also, the delay time varies depending on the load and inertia. If the brake function is provided, the photosensitive member drive gears (drives) 5 and 5 'can be accurately stopped at a position where the photoreceptor drive gears 5 and 5' are reversely rotated by a target angle.

  If the rotation angle of the photosensitive member drive gears (drives) 5 and 5 ′ and the reduction ratio between the motor and the photosensitive member drive gears (drives) 5 and 5 ′ are known, the necessary reverse rotation amount of the motor can be known, and thus the necessary rotations. Just reverse the number and stop. At this time, if the stepping motor is used, the number of rotations can be controlled by the number of steps, so that the photosensitive member drive gears (drives) 5 and 5 ′ can be rotated and stopped with higher accuracy.

Example 7: An example in which a joint is used for driving connection between the photosensitive member driving gear (driven) and the photosensitive member. In FIG. 11, the driving gear 7, the power transmission gear 6, the photosensitive member driving gear (driving) 5, and the transfer member 2 The configuration is the same as in FIG. The difference is that a drive joint 18 and a photoconductor joint 19 are provided between the photoconductor drive gears (drives) 5 and the photoconductors 1A to 1D and are connected by these joints.

  The station A will be described with reference to FIG. The photoconductor joint 19 is attached and fixed to the end of the photoconductor 1A. The drive joint 18 connects the photoreceptor joint 19 and the photoreceptor drive gear (drive) 5. The photoconductor drive gear (drive) 5, the drive joint 18, the photoconductor joint 19, and the photoconductor 1A are configured on the same axis.

At the end of the drive joint 18 facing the photoconductor joint 19, four protrusions protrude in the axial direction on a circle centering on the axis, and these are fitted and coupled to the photoconductor joint 19. . At the end of the drive joint 18 facing the photoconductor drive gear (drive) 5, the same shape as the concavo-convex shape portion 11 provided on the photoconductor drive gear (driven) 4 in the above example is formed. Thus, power can be transmitted with the phase shifted in the same manner as described in Example 1.
In the configuration in which the photosensitive member driving gear (driving) 5 and the photosensitive member gear 3 are jointly connected and a plurality of photosensitive members are connected and driven by one motor, the photosensitive member driving gear (driving) 5 of the photosensitive member driving gear (driving) 5 is assembled. Although it is possible to assemble with the phase of the eccentricity being matched, components such as “photoconductor load fluctuation” and “phase shift due to joint coupling” which are speed fluctuation factors other than the gear eccentricity cannot be matched.
Similarly, in the connection by the joint in this example, the photosensitive member driving gear (driving) 5 and the driving joint 18 are drivingly connected by the uneven portion 9 and the uneven portion 11. In such a configuration, it is possible to adjust the phase including a phase shift that occurs in the joint portion.

Example 8: Example in which driving sources are separated A plurality of driving sources are provided in which the driving source for the color image forming photoconductor and the monochrome image forming photoconductor is replaced with a single driving source.
As shown in FIG. 13, for the monochrome image station A, a new driving gear 7 ′ driven by a motor other than the driving gear 7 for driving the full-color stations B, C, D is newly provided. And is meshed with the photosensitive member drive gear (drive) 5. In addition to the effect of extending the life of the photoconductor by separately driving the color image forming photoconductor and the monochrome image forming photoconductor in this way, the phase of the speed fluctuation between the full-color photoconductors is matched. It is possible to reduce color misregistration between three colors. Further, this method is advantageous for power consumption and the life of the photoconductor because the full color photoconductor is not driven when printing a monochrome image.

Example 9: Example in which means for detecting rotational position of photoconductor is provided Around each of the photoconductors 1A to 1D, means for detecting the rotational position of the photoconductor is provided. According to this configuration, the phase of the speed fluctuation between the monochrome photoconductor 1A and the full color photoconductors 1B to 1D can be matched.

Example 10: Example in which the transfer member and the photosensitive member can be brought into contact with and separated from each other. When the phase adjustment using the concavo-convex shape portion is performed, the photosensitive member is repeatedly rotated and stopped. Since the rotation state at that time is different for each color, a speed difference is generated between the transfer member and the photosensitive member. Due to this speed difference, rubbing occurs between the surface of the photosensitive member and the surface of the transfer member, which causes a reduction in the lifetime of the photosensitive member and the transfer member. In this example, the structure including the transfer body 2, the drive shaft 8, the driven shaft 8 ′, the drive source, and the like is swung around one end side of the unit, and the opposite side of the fulcrum is swung by the cam. Thus, the transfer body 2 can be brought into contact with and separated from the photoreceptors 1A to 1D. Alternatively, a means for moving the photosensitive member in the vertical direction or a method for moving the transfer member in the vertical direction may be employed. Thereby, since the transfer body 2 and the photoconductors 1A to 1D can be separated from each other at the time of phase adjustment, it is possible to prevent the life of the transfer body and the photoconductors 1A to 1D from being reduced.

Example 11: Example of detecting the replacement timing of a photoconductor or a replaceable unit including the photoconductor The photoconductors 1A to 1D are each configured as a single unit or a cartridge including the photoconductor and the developing device. In the configuration in which periodic maintenance is performed, it is possible to replace these units or the like by, for example, counting the cumulative value of the number of print processing sheets. Since it is only necessary to know the rotational speed of the photoconductor, the rotational speed may be calculated from the number of printed sheets or an actual rotational speed detecting means may be provided. If the replacement time of the unit is detected by the counting means, the phase adjustment of the present invention can be performed in accordance with the replacement time of the photosensitive member, the unit, the cartridge, or the like. By performing the two operations in a stopped state, it is possible to adjust the phase only in the most necessary situation, and therefore it is possible to minimize the down time of the image forming apparatus.

1 is a front view illustrating a main part of an image forming apparatus according to the present invention. FIG. 3 is an exploded perspective view showing a main part of a photoconductor drive system gear train including a photoconductor drive gear (drive). It is a perspective view of a photoreceptor driving gear (driven). FIG. 3 is a front view showing a main part of a photoconductor drive system gear train. It is the figure which expanded and showed the part for semicircle of the uneven | corrugated shaped part 11 on the straight line. It is a partial front view of a transfer body on which a test pattern is formed. It is the flowchart explaining the procedure of the phase adjustment in a control means. It is the figure which expanded and showed the part for semicircle of the uneven | corrugated shaped part 11 on the straight line. FIG. 3 is a front view showing a main part of a photoconductor drive system gear train. It is a figure explaining the speed fluctuation of each photoconductor. FIG. 2 is a front view illustrating a main part of an image forming apparatus having a configuration using a joint in a photosensitive member driving system. It is a disassembled perspective view explaining the structure using a joint. FIG. 2 is a front view illustrating a main part of an image forming apparatus in which a driving unit is divided for monochrome and full color.

Explanation of symbols

1A, 1B, 1C, 1D Photoconductor 2 Transfer body 3 Photoconductor gear 4 Photoconductor drive gear (driven)
5, 5 'photoreceptor drive gear (drive)
6, 6 'Power transmission gear 7, 7' Driving gear 9, 9 'Concavity and convexity portion 10 Convex portion 10a Contact surface 10b Slide surface 11, 11' Concavity and convexity portion 12 Convex portion 12a Contact surface 12b Slide surface 13 Axis 14 Pressure spring 15 Detection means 16 Test pattern 17 Stopper 18 Drive joint 19 Photoconductor joint A, B, C, D Station

Claims (15)

In an image forming apparatus having a plurality of photoconductors coupled so as to be driven by a single drive source, and a transfer body to which an image of these photoconductors is transferred,
A photosensitive member driving gear (driving) and a photosensitive member driving gear (driven) which are disposed adjacent to each other on the same axis and are provided with a pair of concavo-convex shape portions which can mesh with each other on the opposite side surface portions;
The concavo-convex shape portion includes a plurality of concavo-convex portions formed along the circumference of a circle centered on the axis, and the ridge portion is formed on the photosensitive member driving gear (covered) when the photosensitive member driving gear (driving) rotates in one direction. The photosensitive member driving gear (driving) rotates in a direction opposite to the one direction with respect to the photosensitive member driving gear (driven) while meshing with the abutting surface that contacts the convex portion of the driving) and transmits the power. It has a mountain shape formed with a slide surface that allows
These gears are configured such that the interval between the plurality of convex portions is different for each driven photosensitive member, and the driving force is transmitted to the photosensitive member by meshing of the concavo-convex shapes,
An image forming apparatus characterized in that, when the drive source is driven, by rotating the rotation direction in reverse and forward rotation, the meshing positions of the concavo-convex shapes are shifted to adjust the phase relationship of the speed fluctuation of each photoconductor. 2. The image forming apparatus according to claim 1, further comprising reading means for reading an image pattern drawn on the transfer body, wherein the driving source is driven and controlled according to the reading result, and the plurality of photosensitive elements. an image forming apparatus comprising that you adjust the phase shift of the velocity fluctuation of the body. The image forming apparatus according to claim 1, wherein
Said abutment surface consists of a plane parallel to the axial direction, the sliding surface is an image forming apparatus according to claim Rukoto such an inclined surface which intersects the axial direction. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus comprising Rukoto to pressurize the two photoconductor driving gear together drivingly connected with the concave and convex portion in a direction toward the pressing body. The image forming apparatus according to claim 1 ,
With helical gear on the drive side of the gear that is drivingly connected by concave-convex part, the image forming apparatus characterized that you have two gears in the forward rotation of the gear is set the direction twisted so that a force in a direction approaching . The image forming apparatus according to claim 1 ,
An image forming apparatus characterized in that a gear part and a concavo-convex shape part are formed separately and configured integrally . The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus using a DC motor having a brake function as the driving source . The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus characterized by using the stepping motor as the drive source. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus using a drive connection system using a gear for driving connection between the photosensitive member driving gear (driven) and the photosensitive member among the two gears . The image forming apparatus according to any one of claims 1 to 8,
2. An image forming apparatus according to claim 1, wherein a driving connection method using a joint is used for driving connection between the driven gear and the photosensitive member among the two gears. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus characterized in that , instead of a single drive source, a plurality of drive sources are provided separately for a color image forming photosensitive member and a monochrome image forming photosensitive member . The image forming apparatus according to claim 11 .
An image forming apparatus comprising means for detecting a rotational position of a photosensitive member . The image forming apparatus according to any one of claims 1 to 12,
An image forming apparatus, wherein the transfer member and the photosensitive member can be contacted and separated . The image forming apparatus according to claim 1,
An image forming apparatus comprising: means for detecting a replacement timing of the photosensitive member or a replaceable unit including the photosensitive member. The image forming apparatus according to any one of claims 1 to 1 3,
An image forming apparatus, comprising: means for detecting a rotation speed of the photosensitive member or a replaceable unit including the photosensitive member .

Images