JP2006243287A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which has an impact force reduced, which occurs when stopping rotation of a rotary developing unit, and is capable of quickly outputting an image of high quality, with respect to the image forming apparatus wherein an electrostatic latent image is formed and is developed by toner to form a toner image and the toner image is finally transferred and fixed to a recording medium to form an image consisting of the fixed toner image on the recording medium. <P>SOLUTION: Gear teeth of a transmission gear 127 for transmitting a driving force to a gear portion 124a provided in a rotary developing unit 100 are made of plastics, and the number of gear teeth of the gear portion 124a provided in the rotary developing unit 100 is non-integer times as large as the number of teeth of the transmission gear 127. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention forms an electrostatic latent image, develops it with toner, forms a toner image, and finally transfers and fixes the toner image on the recording medium, thereby forming an image composed of the fixed toner image on the recording medium. The present invention relates to an image forming apparatus.

  Conventionally, an electrostatic latent image is formed on an image carrier represented by a photosensitive drum or the like and applied to each of four color toners of yellow (Y), magenta (M), cyan (C), and black (K). By developing the electrostatic latent image using four corresponding developing devices, toner images of each color YMCK are formed on the image carrier, and each color toner image formed on the image carrier is transferred onto the transfer drum. Transfer drum-type full-color image forming apparatus that sequentially superimposes and transfers images onto the electrostatically adsorbed recording paper, and each color toner image formed on the image carrier is sequentially superimposed on the intermediate transfer belt. There is known an intermediate transfer type full color image forming apparatus that transfers (primary transfer) and transfers (secondary transfer) a color toner image superimposed on an intermediate transfer belt onto a recording sheet.

  In such a full-color image forming apparatus, four developing devices corresponding to the four colors of YMCK toners are necessary, but four developing devices each configured independently are arranged in parallel around the periphery of one image carrier. In the full-color image forming apparatus configured as described above, the apparatus becomes large. Accordingly, four developing devices corresponding to the four colors of YMCK toner are provided at positions 90 degrees apart from the center in the circumferential direction of the casing unit having a cylindrical shape disposed so as to face the image carrier. By rotating the arranged developing units, the arranged developing devices are sequentially arranged at the developing positions facing the image carrier so that the electrostatic latent image on the image carrier is developed with toner of each color of YMCK. The so-called rotary developing unit is developed and is currently used in full-color image forming apparatuses such as small color printers and color copying machines. Also known is a tandem type image forming apparatus in which four image carriers corresponding to each of the four colors of YMCK toner are arranged in parallel, and a developing device is arranged at a position facing each image carrier for each of these four image carriers. It has been.

  Although the multi-pass type image forming apparatus provided with the rotary developing unit has a drawback that the image output speed is lower than that of the tandem type image forming apparatus, the tandem type image forming apparatus is more than the multi-pass type image forming apparatus. Since YMCK4 color pixel alignment is difficult, in recent years, in multi-pass type image forming apparatuses, various advantages have been achieved to further increase the image output speed while maintaining the advantage that YMCK4 color pixel alignment is easy. Attempts have been made.

  The rotary developing unit provided in the multi-pass image forming apparatus rotates in the circumferential direction by transmitting the driving force of the motor to a gear provided in the circumferential direction of the casing unit having a cylindrical shape. The developing operation is performed by sequentially arranging four developing devices arranged at positions 90 degrees apart from the center in the circumferential direction at the developing position. Since this developing device is a heavy object in which a toner cartridge, a developing roll, and the like are incorporated, a high-weight rotary developing unit in which four developing devices are arranged has a large moment of inertia. Therefore, the gear provided in the circumferential direction of the casing unit and the gear on the motor side that transmits the driving force to this gear are connected at a high reduction ratio, so that the output torque of the motor is suppressed and driven to rotate. . Further, when the rotary developing unit is rotationally driven to place the developing devices at the developing positions, the stopped state of the rotary developing unit is held using the holding force of the motor itself.

  In recent years, with the increase in image output speed in a multi-pass image forming apparatus, the rotary developing unit is rotated at a high speed, and the load applied to the motor when the motor is driven or stopped is very large. As a means for suppressing the load applied to the motor, a rotary developing unit to which a worm gear is applied as a gear on a motor side or a gear provided in a casing unit has been proposed (for example, see Patent Document 1). The worm gear can take a very large reduction ratio, and can prevent a reverse rotation operation due to a reaction when stopping the rotary developing unit without using a large motor.

However, as described above, since the rotary developing unit is heavy and has a large moment of inertia, even when the rotary developing unit to which the worm gear is applied is used to stop the rotation of the rotary developing unit rotating at high speed. The generated impact force causes vibration on the rotary shaft of the rotary developing unit due to backlash and other backlash between the gear on the motor side and the gear provided on the casing unit, and torsion and distortion of the casing unit. It propagates to a support plate that rotatably supports the developing unit. Further, the impact force generated when the rotation of the rotary developing unit is stopped also acts on the motor connected by the gear, and vibration is generated on the support plate to which the motor is attached. When such vibration propagates to the image carrier or the optical image writing device, the output image is disturbed. Conventionally, even when such vibrations occur, when switching colors for image formation, operations such as forming an electrostatic latent image and transferring a toner image on an image carrier to a transfer body have not been performed. For this reason, the generated vibration was rarely a big problem. However, with the recent increase in image output speed in a multi-pass type image forming apparatus, the switching operation time between colors has been shortened, and the generated vibration has greatly affected image formation. Furthermore, in order to reduce the size and cost of the apparatus, a thin and low-rigidity support plate is used as a support plate for supporting the rotary developing unit, and the time until the generated vibration converges, that is, residual vibration. Has occurred over a long period of time, and the vibration has a greater influence on image formation.
JP-A-5-241418

  In order to reduce the impact force generated when the rotation of the rotary developing unit is stopped, it is conceivable to use a gear whose gear teeth are made of plastic as a gear provided in the casing unit. Since plastic has viscoelastic properties, it can be expected to reduce vibrations caused by impact force. However, since plastic has lower strength than metal, when the above-described impact force is repeatedly generated in a gear made of plastic, the gear teeth of the gear may be reduced in strength and the gear teeth may be damaged.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that can output high-quality images at a high speed with reduced impact force generated when rotation of a rotary developing unit is stopped. is there.

Of the image forming apparatuses of the present invention that achieve the above object, the first image forming apparatus comprises:
A developing device is provided opposite to an image carrier on which an electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with toner, and the electrostatic latent image formed on the image carrier is provided. The image is developed using the developing device to form a toner image on the image carrier, and the toner image is finally transferred and fixed on a predetermined recording medium to fix the toner on the recording medium. In an image forming apparatus for forming an image consisting of an image,
The developing device is
A plurality of developing members for developing the electrostatic latent image formed on the image carrier with toners of different colors are arranged in the circumferential direction, and the gear teeth are arranged in the circumferential direction. A rotating body that has a gear portion and rotates in the circumferential direction when a driving force is transmitted to the gear portion and sequentially arranges the plurality of developing members at positions facing the image carrier;
A frame that rotatably supports the rotating body;
A transmission gear that is rotatably attached to the frame and meshes with the gear portion that transmits driving force to the gear portion, and the gear teeth are made of plastic;
The gear portion is characterized in that the number of gear teeth is a non-integer multiple of the number of teeth of the transmission gear.

  In the first image forming apparatus of the present invention, the gear teeth of the transmission gear for transmitting the driving force to the gear portion provided on the rotating body are made of plastic, so that the rotating body rotates. The impact force generated when stopping is absorbed by the viscoelastic properties of the plastic, and the impact force is alleviated. Therefore, according to the first image forming apparatus, the vibration generated due to the impact force is reduced, and a high-quality image can be output at high speed. In the first image forming apparatus, since the number of gear teeth of the gear portion provided on the rotating body is a non-integer multiple of the number of teeth of the transmission gear, the rotating body rotates to develop with the same color toner. When the gear stops, always different gear teeth of the transmission gear mesh with the gear teeth of the gear portion, and the durability of the gear teeth of the transmission gear made of plastic is improved.

  Here, in the first image forming apparatus of the image forming apparatus according to the present invention, the gear portion has a value obtained by dividing the number of the gear teeth by the number of the plurality of developing members. It is preferable that the relationship satisfying a non-integer multiple of the number is satisfied.

  According to such a preferable form, even when the rotation of the rotating body is stopped to develop with different color toner, always different gear teeth of the transmission gear mesh with the gear teeth of the gear portion, The durability of the gear teeth of the transmission gear whose gear teeth are made of plastic is further improved.

The first image forming apparatus of the image forming apparatus according to the present invention includes:
“An engaging member that is movable between an engaging position that engages with the rotating body and prevents the rotating body from rotating and a retracted position that is separated from the rotating body;
And a moving means for moving the engagement member from the retracted position to the engagement position after the rotation of the rotating body has stopped. "
This is also a preferred form.

  According to the image forming apparatus including the engaging member and the moving unit, the rotation of the rotating body is prevented by the engaging member that moves and engages the rotating body after the rotation of the rotating body stops. The rotating body can be held.

  In the image forming apparatus according to the first aspect of the invention, the first image forming apparatus including the engaging member and the moving unit is configured such that the engaging member is engaged with the gear teeth of the gear portion at the engaging position. In addition, the rotation of the rotating body may be prevented.

  Further, in the first image forming apparatus including the engaging member and the moving unit in the image forming apparatus of the present invention, the gear portion has the number of the gear teeth equal to the number of the plurality of developing members. It is also a preferred form that the number is an integer multiple.

  Each of the plurality of developing members can be disposed at a position facing the image carrier, and the rotating body can be reliably held at that position.

  Furthermore, in the first image forming apparatus including the engaging member and the moving unit, the engaging member meshes with the gear teeth of the gear portion at the engaging position. It may be a non-rotatable gear member.

The second image forming apparatus of the image forming apparatus of the present invention that achieves the above object is
A developing device is provided opposite to an image carrier on which an electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with toner, and the electrostatic latent image formed on the image carrier is provided. The image is developed using the developing device to form a toner image on the image carrier, and the toner image is finally transferred and fixed on a predetermined recording medium to fix the toner on the recording medium. In an image forming apparatus for forming an image consisting of an image,
The developing device is
A plurality of developing members for developing the electrostatic latent image formed on the image carrier with different color toners are arranged in the circumferential direction, and the rotation in the circumferential direction and the stop of the rotation are repeated. A rotating body that sequentially arranges the plurality of developing members at positions facing the image carrier by rotating and stopping in the circumferential direction;
A braking member that comes into contact with a predetermined portion of the rotating body whose rotational speed has decreased due to rotation stoppage,
At least one of the predetermined portion and the braking member absorbs an inertial force that causes the rotating body to continue to rotate in the circumferential direction when the braking member contacts the predetermined portion. It is characterized by.

  According to a second image forming apparatus of the present invention, at least one of the predetermined part of the rotating body and the braking member that contacts the predetermined part of the rotating body whose rotation speed has decreased as the rotation stops is provided. When the braking member comes into contact with a predetermined part, the rotating body absorbs the inertial force that keeps rotating in the circumferential direction, so that the impact force generated when the rotation of the rotating body is stopped is alleviated. . Therefore, according to the second image forming apparatus, vibration generated due to the impact force is reduced, and a high-quality image can be output at high speed.

  Here, in the second image forming apparatus of the image forming apparatus of the present invention, at least one of the predetermined portion and the braking member is made of an elastic body, and the braking member is the predetermined portion. It is preferable that the inertial force is absorbed by elastic deformation when being in contact with.

  Inertial force can be efficiently absorbed by elastic deformation of the elastic body.

  In the second image forming apparatus of the present invention, at least one of the braking member and the predetermined portion is a roller rotatably supported, and the braking member is the predetermined image forming apparatus. A form in which the inertial force is absorbed by rotating by receiving the inertial force when contacting the part is also preferable.

  As the roller rotates, inertial force is absorbed, and wear due to friction when the braking member comes into contact with the predetermined portion is reduced.

  Furthermore, in the second image forming apparatus of the image forming apparatus according to the present invention, the braking member comes into contact with the predetermined part via an elastic mechanism, and when the predetermined member comes into contact with the predetermined part, the elasticity is obtained. It is also a preferred form that the mechanism absorbs the inertial force by elastic deformation.

  According to the present invention, there is provided an image forming apparatus capable of outputting a high-quality image at a high speed with reduced impact force generated when the rotation of the rotary developing unit is stopped.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus to which an embodiment of the first image forming apparatus of the present invention is applied.

  An image forming apparatus 1 shown in FIG. 1 is a multi-pass type image forming apparatus including a rotary developing unit, and forms an electrostatic latent image on a photosensitive drum, and yellow (Y), magenta (M), cyan (C) Image bearing by developing the electrostatic latent image in synchronism with the feeding of an intermediate transfer belt as an intermediate medium using four developing devices corresponding to the four color toners of black (K). A toner image of each color YMCK is formed on the body, and each color toner image formed on the image carrier is sequentially superimposed on the intermediate transfer belt and transferred (primary transfer), and then superimposed on the intermediate transfer belt. This is an intermediate transfer type full-color image forming apparatus that transfers (secondary transfer) and fixes a combined color toner image onto a sheet as a recording medium.

  The image forming apparatus 1 shown in FIG. 1 includes a photosensitive drum 40 that rotates in a clockwise arrow A direction. In addition, the image forming apparatus 1 is semiconductive, which is stretched around a driving roll 31, a tension roll 32, a driven roll 33, a primary transfer roll 41, and a counter roll 52 and circulates in the counterclockwise arrow B direction. The intermediate transfer belt 30, a batch transfer device 50 that performs secondary transfer, and a fixing device 80 that fixes an unfixed toner image on a sheet. The surface of the photosensitive drum 40 is in contact with the intermediate transfer belt 30. The primary transfer roll 41 is disposed at a position facing the photosensitive drum 40 with the intermediate transfer belt 30 interposed therebetween, and a portion where the photosensitive drum 40 and the intermediate transfer belt 30 are in contact is a primary transfer position.

  Further, around the photosensitive drum 40, four color toners of YMCK are disposed at positions 90 ° apart from the center in the circumferential direction of the optical writing unit 42, the charger 43, and the casing unit 120 having a cylindrical shape. Four developing devices 110Y, 110M, 110C, and 110K corresponding to each are arranged, and the driving force of the stepping motor 126 (see FIG. 2) is applied to the gear portion 124a (see FIG. 2) provided in the circumferential direction of the casing unit 120. Is transmitted, the rotary developing unit 100 that rotates in the counterclockwise arrow C direction is provided. The rotary developing unit 100 corresponds to an example of a rotating body referred to in the present invention. The rotary developing unit 100 is disposed on the upstream side of the primary transfer position around the photosensitive drum 40. The optical writing unit 42 is disposed further upstream than the rotary developing unit 100, and the charger 43 is disposed further upstream than the optical writing unit 42.

  The surface of the photosensitive drum 40 is uniformly charged by the charger 43. The surface of the photosensitive drum 40 uniformly charged by the charger 43 is irradiated with laser light from the optical writing unit 42 to form an electrostatic latent image on the surface of the photosensitive drum 40. The four developing devices 110Y, 110M, 110C, and 110K arranged in the rotary developing unit 100 adopt a two-component developing method, and are installed in toner cartridges built in the developing devices 110Y, 110M, 110C, and 110K. Contains a two-component developer comprising a magnetic carrier and toner. The developing devices 110Y, 110M, 110C, and 110K arranged in the rotary developing unit 100 also include developing rolls 111Y, 111M, 111C, and 111K corresponding to an example of the developing member according to the present invention. On the peripheral surface of each developing roll 111Y, 111M, 111C, 111K, a developer layer (so-called magnetic layer) in which a magnetic carrier to which toner is attached is formed is formed, and four developing devices 110Y, 110M, 110C, 110K are formed. Is rotated in the counterclockwise arrow C direction so that the arranged developing devices 110Y, 110M, 110C, and 110K are sequentially arranged at the developing positions facing the photosensitive drum 40. Then, the YMCK color toners are supplied from the developer layer to the surface of the photosensitive drum 40 carrying the electrostatic latent image. The electrostatic latent image is developed upon receipt of toner and becomes a toner image.

  A transfer bias having a polarity opposite to the polarity of the toner is applied to the primary transfer roll 41, and the YMCK color toner images formed on the surface of the photoconductive drum 40 are intermediately transferred from the surface of the photoconductive drum 40. When the intermediate transfer belt 30 rotates four times on the surface of the belt 30, the color toner images overlapped on the intermediate transfer belt 30.

  The batch transfer device 50 includes a secondary transfer roll 51 disposed in pressure contact with the toner image carrying surface side of the intermediate transfer belt 30 and a counter roll 52 disposed on the back side of the intermediate transfer belt 30. The intermediate transfer belt 30 is sandwiched between the two rolls 51 and 52. Between these two rolls 51 and 52 is a secondary transfer position.

  Further, the image forming apparatus 1 shown in FIG. 1 is provided with a registration roll 71 for feeding the paper P conveyed from the paper tray 60 to the secondary transfer position, and the paper P is transferred to the secondary transfer position at a predetermined timing. It is sent to. At the secondary transfer position, the color toner images overlapped on the intermediate transfer belt 30 are transferred onto the fed paper P.

  Further, the image forming apparatus 1 is provided with a conveyance belt 72 that conveys the paper P on which the color toner image is secondarily transferred, and the paper P conveyed by the conveyance belt 72 is sent to the fixing device 80. . The fixing device 80 includes a fixing roll 81 having a heating mechanism 811 and a pressure roll 82 provided so as to face the fixing roll 81. When the paper P that has passed the secondary transfer position is transported between the fixing roll 81 and the pressure roll 82 facing each other, the toner constituting the color toner image on the paper P is heated by the heating mechanism of the fixing roll 81. 811 is melted and fixed on the paper P.

  Here, the feature of the image forming apparatus 1 shown in FIG. 1 as an embodiment of the present invention is related to the rotary developing unit 100 provided in the image forming apparatus 1. Hereinafter, the rotary developing unit 100 will be described. Will be described in detail.

  FIG. 2 is an external perspective view of the rotary developing unit 100 shown in FIG. 2 shows the rotary developing unit 100 in which one developing device 110Y is mounted in the circumferential direction of the casing unit 120. The rotary developing unit 100 is the image forming apparatus 1 shown in FIG. When mounted on the four developing devices 110Y, 110M, 110C, and 110K, the developing units 110Y, 110M, 110C, and 110K are arranged at positions that are 90 degrees apart from the center of the casing unit 120 in the circumferential direction.

  As shown in FIG. 2, the rotary developing unit 100 includes a casing unit 120 and four developing devices 110Y, 110M, 110C, which are arranged at positions 90 ° apart from the center of the casing unit 120 in the circumferential direction. 110K.

  The casing unit 120 includes two developing device support plates 121 and 122 that support the developing devices 110Y, 110M, 110C, and 110K, and a rotating shaft 123a that is pivotally supported by the frame 125, and includes two developing device support plates 121. , 122 and a rotary developing unit rotating member 124 having a gear portion 124a with gear teeth provided in the circumferential direction and fixed to one developing device support plate 121. It is configured. The gear teeth of the gear portion 124a are made of metal, and the gear portion 124a corresponds to an example of the gear portion according to the present invention. The developing device 110Y includes a developing roll 111Y and a toner cartridge 112Y. Here, of the four developing devices 110Y, 110M, 110C, and 110K, only one developing device 110Y corresponding to yellow (Y) toner is shown, but the other three developing devices 110M, 110C, Similarly to the developing device 110Y, 110K also includes a developing roll and a toner cartridge. These four developing devices 110Y, 110M, 110C, and 110K are supported by the two developing device support plates 121 and 122 of the casing unit 120, so that they are separated by 90 ° from the circumferential center of the casing unit 120. Four developing devices 110Y, 110M, 110C, and 110K are arranged at the positions.

  FIG. 2 also shows a stepping motor 126 fixed to the frame 125. The gear teeth of the transmission gear 127 attached to the rotating shaft 126a of the stepping motor 126 are made of plastic having viscoelastic characteristics, and the transmission gear 127 corresponds to an example of the transmission gear according to the present invention. Is. The transmission gear 127 meshes with the gear portion 124a provided in the rotary developing unit, and when the stepping motor 126 is driven, the driving force is applied to the rotary developing unit rotating member 124 via the transmission gear 127 and the gear portion 124a. By being transmitted, the rotary developing unit 100 rotates.

  As described above, since the gear teeth of the gear portion 124a are made of metal and the gear teeth of the transmission gear 127 are made of plastic, the developing devices 110Y, 110M, The impact force generated when the rotation of the rotary developing unit 100 is stopped in order to place the 110C and 110K at the development position facing the photosensitive drum 40 is absorbed by the viscoelastic property of the plastic, and the impact force is reduced. The Therefore, according to the image forming apparatus 1 (see FIG. 1) provided with the rotary developing unit 100, the vibration generated due to the impact force is also prevented from propagating to the frame 125, and high-quality images are output at high speed. can do. Furthermore, since the gear teeth of the transmission gear 127 are made of plastic, there is an effect of reducing noise caused by the meshing of the gears.

  Further, in the gear portion 124a provided in the rotary developing unit 100 shown in FIG. 2, the number of gear teeth of the gear portion 124a is a non-integer number of teeth of the transmission gear 127 attached to the rotating shaft 126a of the stepping motor 126. In this gear portion 124a, a value obtained by dividing the number of gear teeth of the gear portion 124a by "4" that is the number of the plurality of developing rolls 111Y, 111M, 111C, 111K is transmitted. The relationship of becoming a non-integer multiple of the number of teeth of the gear 127 is also satisfied.

  Here, referring to FIG. 3 and FIG. 4, a gear portion provided on the rotary developing unit and having gear teeth made of metal, and a transmission gear having gear teeth made of plastic attached to the rotating shaft of the stepping motor, The relationship will be described.

  FIG. 3 shows a transmission gear 201 that meshes with a gear portion 200a provided in the rotary developing unit 200 when the developing devices arranged in the conventional rotary developing unit 200 are arranged at a developing position facing the photosensitive drum. It is a figure which shows a stop position. FIG. 3A is a view when a developing device corresponding to yellow (Y) toner is disposed at a developing position facing the photosensitive drum, and FIG. 3B is magenta (M). FIG. 3C is a view when the developing device corresponding to the toner of FIG. 3 is disposed at the developing position facing the photosensitive drum, and FIG. 3C shows the developing device corresponding to the cyan (C) toner and the photosensitive drum. FIG. 3D is a diagram when the developing device corresponding to the black (K) toner is disposed at the developing position facing the photosensitive drum. is there.

  In the conventional example shown in FIG. 3, the gear portion 200a made of metal provided in the rotary developing unit 200 has a transmission gear made of plastic in which the number of gear teeth of the gear portion 200a is attached to the rotating shaft of the stepping motor. The gear portion 200a has a value obtained by dividing the number of gear teeth of the gear portion 200a by “4”, which is the number of the plurality of developing rolls. The relation of becoming an integral multiple of the number of teeth of 201 is also satisfied. In the conventional rotary developing unit 200 configured as described above, when the rotation of the rotary developing unit 200 is stopped because each developing device is disposed at the developing position facing the photosensitive drum, the transmission gear 201 made of plastic is used. Since the same gear teeth mesh with the gear teeth of the gear portion 200a made of metal, the above-described impact force repeatedly acts on the same gear teeth of the transmission gear 201 made of plastic. As described in the section “Problems to be Solved by the Invention”, since plastic has lower strength than metal, such an impact force is applied to the same gear tooth of the transmission gear 201 made of plastic. If it occurs repeatedly, the strength of the gear teeth may be reduced and the gear teeth may be damaged.

  4 shows the rotary developing unit 100 when the developing devices 110Y, 110M, 110C, and 110K arranged in the rotary developing unit 100 shown in FIGS. 1 and 2 are arranged at the developing positions facing the photosensitive drum 40. FIG. It is a figure which shows the stop position of the transmission gear 127 which meshes with the gear part 124a provided in FIG. 4A is a diagram when the developing device 110Y corresponding to the yellow (Y) toner is disposed at the developing position facing the photosensitive drum 40, and FIG. 4B is a diagram showing magenta ( FIG. 4C is a diagram when the developing device 110M corresponding to the toner M) is disposed at the developing position facing the photosensitive drum 40, and FIG. 4C illustrates the developing device 110C corresponding to the cyan (C) toner. FIG. 4D is a development position where the developing device 110K corresponding to the black (K) toner faces the photosensitive drum 40. FIG. It is a figure at the time of arrange | positioning.

  As shown in FIG. 4, since the gear teeth of the transmission gear 127 whose gear teeth are made of plastic always mesh with the gear teeth of the gear portion 124a made of metal, the gear teeth are the same as those of the transmission gear 127 made of plastic. The above-described impact force is prevented from being repeatedly generated on the gear teeth, and the durability of the gear teeth of the transmission gear 127 made of plastic is improved.

  Here, the gear portion referred to in the present invention is such that the number of gear teeth is a non-integer multiple of the number of teeth of the transmission gear, and the value obtained by dividing the number of gear teeth by the number of developing rollers. In this example, the relationship that satisfies the relationship of becoming a non-integer multiple of the number of teeth of the transmission gear has been described. However, the gear portion according to the present invention is not limited to this, and the number of gear teeth is the number of teeth of the transmission gear As long as it is a non-integer multiple of. In this case, when the rotation of the rotating body stops to develop with toner of the same color, the different gear teeth of the transmission gear mesh with the gear teeth of the gear portion, and the gear teeth of the transmission gear made of plastic are used. The durability of the gear teeth is improved.

  The image forming apparatus 1 shown in FIG. 1 is also provided with a gear member and a gear member moving means for preventing the rotation of the rotary developing unit 100 after the rotation of the rotary developing unit 100 shown in FIGS. Hereinafter, the gear member and the gear member moving means will be described with reference to FIGS. This gear member corresponds to an example of the gear member referred to in the present invention, and the gear member moving means corresponds to an example of the moving means referred to in the present invention.

  FIG. 5 is a diagram illustrating a state where the gear member 131 is located at a retracted position separated from the rotary developing unit 100, and FIG. 6 is a diagram illustrating the gear member 124a provided in the rotary developing unit 100. FIG. 7 is a view showing a state where the teeth are engaged with each other and located at a meshing position where rotation of the rotary developing unit 100 is prevented, and FIG. 7 is a view of the state shown in FIG. 6 as viewed from the left side in FIG.

  While the stepping motor 126 is driven and the driving force is transmitted to the rotary developing unit 100 via the gear portion 124a and the transmission gear 127 provided in the rotary developing unit 100, the rotary developing unit 100 is rotated. As shown in FIG. 5, the gear member 131 is located at a retracted position separated from the rotary developing unit 100. The rotary developing unit 100 is rotated in order to place the developing devices 110Y, 110M, 110C, and 110K (see FIG. 1) arranged in the rotary developing unit 100 at the developing positions facing the photosensitive drum 40 (see FIG. 1). After the stop, the gear member 131 is moved from the retracted position shown in FIG. 5 to the meshing position shown in FIGS. 6 and 7 by the gear member moving means 132 using a solenoid, and at this meshing position, the rotary developing unit 100 is moved. Meshes with the gear teeth of the gear portion 124a provided on the gear. The gear member 131 is non-rotatable. When the non-rotatable gear member 131 meshes with the gear portion 124a, the rotation of the rotary developing unit 100 is prevented, and the stopped state of the rotary developing unit 100 is reliably maintained. The Further, the gear portion 124a provided in the rotary developing unit 100 is an integer multiple of “4”, which is the number of the gear teeth of the gear portion 124a, which is the number of the plurality of developing rolls 111Y, 111M, 111C, 111K. There is something. Therefore, when the rotation of the rotary developing unit 100 is stopped, the gear member 131 is surely engaged with the gear teeth of the gear portion 124 a provided in the rotary developing unit 100, and is arranged in the rotary developing unit 100. Further, when each developing device 110Y, 110M, 110C, 110K (see FIG. 1) is arranged at a developing position facing the photosensitive drum 40 (see FIG. 1), the mutual development is always in an appropriate positional relationship. The stopped state of the unit 100 is maintained.

  Here, an example in which the engagement member according to the present invention is a non-rotatable gear member has been described. However, the engagement member according to the present invention is not limited to this, for example, the gear teeth of the gear portion. Any member that engages with the rotating body referred to in the present invention and prevents the rotating body from rotating, such as a columnar member or a rod-shaped member that engages with the shaft, may be used.

  Above, description of 1st Embodiment of this invention is complete | finished.

  Next, as a second embodiment, at least one of a predetermined part of the rotary developing unit and a braking member that contacts the predetermined part of the rotary developing unit whose rotational speed has decreased due to the rotation stop being An embodiment will be described in which the rotary developing unit absorbs the inertial force that keeps rotating in the circumferential direction when contacted.

  In the second embodiment described below, since the apparatus configuration is substantially the same as the apparatus configuration described in the first embodiment, the difference from the first embodiment is noted, and the same elements are denoted by the same reference numerals. The description is omitted.

  FIG. 8 is a schematic configuration diagram of an image forming apparatus to which an embodiment of the second image forming apparatus of the present invention is applied.

  In the image forming apparatus 2 shown in FIG. 8, the upstream side of the primary transfer position around the photosensitive drum 40 is separated by 90 ° from the circumferential center of the casing unit 320 having a cylindrical shape. The four developing devices 310Y, 310M, 310C, and 310K are arranged at the positions, and the driving force of a stepping motor (not shown) is transmitted to the gear portion 324a (see FIG. 9) provided in the circumferential direction of the casing unit 320. And a rotary developing unit 300 that rotates counterclockwise in the direction of arrow C is provided. The rotary developing unit 300 corresponds to an example of a rotating body referred to in the present invention. The four developing devices 310Y, 310M, 310C, and 310K arranged in the rotary developing unit 300 adopt a two-component developing method, and are installed in toner cartridges built in the developing devices 310Y, 310M, 310C, and 310K. Contains a two-component developer comprising a magnetic carrier and toner. The developing devices 310Y, 310M, 310C, and 310K arranged in the rotary developing unit 300 also include developing rolls 311Y, 311M, 311C, and 311K corresponding to an example of the developing member according to the present invention. On the peripheral surface of each developing roll 311Y, 311M, 311C, 311K, a developer layer (so-called magnetic layer) in which a magnetic carrier to which toner is attached is formed is formed, and four developing devices 310Y, 310M, 310C, 310K are formed. Is rotated in the counterclockwise arrow C direction so that the arranged developing devices 310Y, 310M, 310C, 310K are sequentially arranged at developing positions facing the photosensitive drum 40. Then, the YMCK color toners are supplied from the developer layer to the surface of the photosensitive drum 40 carrying the electrostatic latent image. The electrostatic latent image is developed upon receipt of toner and becomes a toner image.

  Here, the feature of the image forming apparatus 2 shown in FIG. 8 as an embodiment of the present invention is related to the rotary developing unit 300 provided in the image forming apparatus 2. Hereinafter, the rotary developing unit 300 will be described. Will be described in detail.

  FIG. 9 is an external perspective view of the rotary developing unit 300 shown in FIG. 9 shows the rotary developing unit 300 in which one developing device 310Y is mounted in the circumferential direction of the casing unit 320. The rotary developing unit 300 is the image forming apparatus 2 shown in FIG. When mounted on the four developing devices 310Y, 310M, 310C, and 310K, the developing units 310Y, 310M, 310C, and 310K are arranged at positions 90 degrees apart from the center of the casing unit 320 in the circumferential direction.

  As shown in FIG. 9, the rotary developing unit 300 includes a casing unit 320 and four developing devices 310Y, 310M, 310C, which are arranged at positions 90 ° apart from the center of the casing unit 320 in the circumferential direction. 310K.

  The casing unit 320 includes two developing device support plates 321 and 322 that support the developing devices 310Y, 310M, 310C, and 310K, and a rotating shaft 323a that is pivotally supported by the frame 325, and includes two developing device support plates 321. , 322 and a developing device support plate connecting member 323, and a rotary developing unit rotating member 324 having a gear portion 324a having gear teeth provided in the circumferential direction and fixed to one developing device support plate 321. It is configured. Further, on the inner peripheral surface of the rotary developing unit rotating member 324, there are provided four projecting portions 324b made of an elastic body, which corresponds to an example of a predetermined portion referred to in the present invention. The developing device 310Y includes a developing roll 311Y and a toner cartridge 312Y. Here, of the four developing devices 310Y, 310M, 310C, and 310K, only one developing device 310Y corresponding to yellow (Y) toner is shown, but the other three developing devices 310M, 310C, Similarly to the developing device 310Y, 310K includes a developing roll and a toner cartridge. The four developing devices 310Y, 310M, 310C, and 310K are supported by the two developing device support plates 321 and 322 of the casing unit 320, so that they are separated by 90 ° from the circumferential center of the casing unit 320. Four developing devices 310Y, 310M, 310C, and 310K are arranged at the positions.

  The rotary developing unit 300 configured as described above includes a transmission gear 327 (see FIGS. 10 and 11) attached to a rotation shaft of a stepping motor (not shown) fixed to the frame 325, and a gear provided in the rotary developing unit. When the portion 324a is engaged and the stepping motor is driven, the driving force is transmitted to the rotary developing unit rotating member 324 via the transmission gear 327 and the gear portion 324a, thereby rotating.

  Hereinafter, with reference to FIGS. 10 to 12, the operation of the four protrusions 324 b made of an elastic body provided on the inner peripheral surface of the rotary developing unit rotating member 324 described above will be described.

  FIG. 10 is a diagram illustrating a state in which the roller 331 is separated from the inner peripheral surface of the rotary developing unit rotating member 324. FIG. 11 is a diagram illustrating the roller 331 provided on the inner peripheral surface of the rotary developing unit rotating member 324. FIG. 12 is a diagram illustrating a state of a position in contact with the projected portion 324b, and FIG. 12 is a diagram of the state illustrated in FIG. 11 as viewed from the upper side in FIG. The roller 331 is in contact with the protrusion 324b provided on the rotary developing unit 300 whose rotational speed has decreased as the rotation of the rotary developing unit 300 stops, and corresponds to an example of a braking member according to the present invention. Is.

  While the stepping motor (not shown) is driven and the driving force is transmitted to the rotary developing unit 300 via the gear portion 324a and the transmission gear 327 provided in the rotary developing unit 300 and the rotary developing unit 300 rotates, As shown in FIG. 10, the roller 331 is located at a position separated from the inner peripheral surface of the rotary developing unit rotating member 324. Rotation of the rotary developing unit 300 for disposing each developing device 310Y, 310M, 310C, 310K (see FIG. 9) arranged in the rotary developing unit 300 at a developing position facing the photosensitive drum 40 (see FIG. 9). When the rotation speed decreases, the roller moving means 332 using a solenoid causes the roller 331 to be shown in FIGS. 11 and 12 from the position separated from the inner peripheral surface of the rotary developing unit rotating member 324 shown in FIG. The rotary developing unit rotating member 324 is moved to a position where it comes into contact with the protruding portion 324b provided on the inner peripheral surface, and the roller 331 is elastically deformed when contacting the protruding portion 324b made of an elastic body. The inertial force that the developing unit 300 tries to continue to rotate is absorbed. The inertial force is also absorbed by the rotation of the roller 331, and wear of the protrusion 324b due to friction when the roller 331 contacts the protrusion 324b is reduced. After the roller 331 comes into contact with the protrusion 324b and the rotation of the rotary developing unit 300 stops, the roller 331 is moved to a position away from the inner peripheral surface of the rotary developing unit rotating member 324 by the roller moving unit 332.

  According to the image forming apparatus 2 (see FIG. 8) provided with the rotary developing unit 300 described above, the impact force generated when the rotation of the rotary developing unit 300 is stopped is the elasticity of the protrusion 324b made of an elastic body. Since it is relieved by the deformation and the absorption of the inertial force due to the rotation of the roller 331, the vibration generated due to the impact force is reduced from propagating to the frame 325, and a high-quality image can be output at high speed. it can.

  Next, referring to FIG. 13 and FIG. 14, when the braking member according to the present invention comes into contact with the predetermined portion according to the present invention, the inertial force that the rotary developing unit continues to rotate in the circumferential direction is absorbed. Another embodiment will be described.

  FIG. 13 is a diagram illustrating a state where the rubber roller 431 is separated from the inner peripheral surface of the rotary developing unit rotating member 424. FIG. 14 is a diagram illustrating the rubber roller 431 provided on the inner peripheral surface of the rotary developing unit rotating member 424. It is a figure which shows the state of the position which contacted the projected part 424b.

  In FIG. 13, two developing device support plates for supporting four developing devices, a developing device support plate connecting member for connecting two developing device support plates, and a gear portion 424a having gear teeth provided in the circumferential direction. And is arranged at a position 90 degrees apart from the center in the circumferential direction of the casing unit 420. A rotary developing unit 400 composed of four developed developing devices is shown. Further, on the inner peripheral surface of the rotary developing unit rotating member 424, there are provided four protrusions 424b made of metal corresponding to an example of a predetermined portion referred to in the present invention. Also shown in FIG. 13 is a rubber roller 431 made of an elastic body that comes into contact with the protrusion 424b provided on the rotary developing unit 400 whose rotational speed has decreased as the rotation of the rotary developing unit 400 stops. The rubber roller 431 is disposed at one end of a shaft 432 that is displaced about a fulcrum 432a, and a spring 433 is disposed at the other end of the shaft 432. The rubber roller 431 corresponds to an example of a braking member according to the present invention, and the spring 433 corresponds to an example of an elastic mechanism according to the present invention.

  A stepping motor (not shown) is driven, and the driving force is transmitted to the rotary developing unit 400 via a gear portion 424a provided in the rotary developing unit 400 and a transmission gear 427 attached to the rotation shaft of the stepping motor, thereby rotating the developing. While the unit 400 is rotating, as shown in FIG. 13, the rubber roller 431 is located at a position away from the inner peripheral surface of the rotary developing unit rotating member 424. When the rotation speed is reduced with the rotation of the rotary developing unit 400 for disposing the developing devices arranged in the rotary developing unit 400 at the developing position facing the photosensitive drum, the rubber roller moving means 434 using a solenoid The rubber roller 431 comes into contact with the protrusion 424b provided on the inner peripheral surface of the rotary developing unit rotating member 424 shown in FIG. 14 from a position separated from the inner peripheral surface of the rotary developing unit rotating member 424 shown in FIG. The rubber roller 431 comes into contact with the protrusion 424b made of metal. When the rubber roller 431 comes into contact with the protrusion 424b, the spring 433 provided at the other end of the shaft 432 provided with the rubber roller 431 is elastically deformed, so that the inertial force that the rotary developing unit 400 continues to rotate is generated. Absorbed. The inertia force is also absorbed by the elastic deformation of the rubber roller 431. Further, the inertial force is absorbed by the rotation of the rubber roller 431, and wear of the protrusion 424b due to friction when the rubber roller 431 contacts the protrusion 424b is reduced. After the rubber roller 431 comes into contact with the protrusion 424b and the rotation of the rotary developing unit 400 stops, the rubber roller 431 is moved to a position separated from the inner peripheral surface of the rotary developing unit rotating member 424 by the rubber roller moving means 434.

  Also in the image forming apparatus provided with the rotary developing unit 400 shown in FIGS. 13 and 14, the impact force generated when the rotation of the rotary developing unit 400 is stopped causes the elastic deformation of the spring 433 and the elastic deformation of the rubber roller 431. Since the inertial force is absorbed by the rotation of the rubber roller 431, the vibration generated due to the impact force is reduced from propagating to the frame, and a high-quality image can be output at high speed.

  In each of the above-described embodiments, an example in which the present invention is applied to an intermediate transfer type full-color image forming apparatus among multi-pass type image forming apparatuses including a rotary developing unit has been described. For example, an electrostatic latent image is formed on a photosensitive drum, and the electrostatic latent image is developed by using four developing devices corresponding to the four color toners of YMCK. A transfer drum type in which a toner image of each color of YMCK is formed on a carrier and the toner images of each color formed on the image carrier are sequentially superimposed and transferred onto a recording sheet electrostatically adsorbed on the transfer drum. The present invention can also be applied to a full color image forming apparatus.

1 is a schematic configuration diagram of an image forming apparatus to which an embodiment of a first image forming apparatus of the present invention is applied. FIG. 2 is an external perspective view of the rotary developing unit 100 shown in FIG. When the developing devices arranged in the conventional rotary developing unit 200 are arranged at the developing position facing the photosensitive drum, the stop position of the transmission gear 201 that meshes with the gear portion 200a provided in the rotary developing unit 200 is shown. FIG. The developing devices 110Y, 110M, 110C, and 110K arranged in the rotary developing unit 100 shown in FIGS. 1 and 2 are provided in the rotary developing unit 100 when they are arranged at the developing positions facing the photosensitive drum 40. It is a figure which shows the stop position of the transmission gear 127 which meshes with the gear part 124a. FIG. 6 is a view showing a state where the gear member 131 is located at a retracted position separated from the rotary developing unit 100. FIG. 6 is a diagram illustrating a state where the gear member 131 is located at a meshing position that meshes with a gear tooth of a gear portion 124 a provided in the rotary developing unit 100 and prevents the rotary developing unit 100 from rotating. It is the figure which looked at the state shown in FIG. 6 from the left side toward FIG. 1 is a schematic configuration diagram of an image forming apparatus to which an embodiment of a second image forming apparatus of the present invention is applied. It is the external appearance perspective view which looked at the rotary developing unit 300 shown in FIG. FIG. 10 is a diagram illustrating a state where a roller 331 is separated from an inner peripheral surface of a rotary developing unit rotating member 324. FIG. 10 is a diagram showing a state where a roller 331 is in contact with a protrusion 324b provided on the inner peripheral surface of a rotary developing unit rotating member 324. It is the figure which looked at the state shown in FIG. 11 from the upper side toward FIG. FIG. 11 is a view showing a state where a rubber roller 431 is separated from an inner peripheral surface of a rotary developing unit rotating member 424. FIG. 11 is a diagram showing a state in which a rubber roller 431 is in contact with a protrusion 424b provided on the inner peripheral surface of a rotary developing unit rotating member 424.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 30 Intermediate transfer belt 31 Drive roll 32 Tension roll 33 Driven roll 40 Photosensitive drum 41 Primary transfer roll 42 Optical writing unit 43 Charger 50 Batch transfer apparatus 51 Secondary transfer roll 52 Opposite roll 60 Paper tray 71 Resist Ration roll 72 conveying belt 80 fixing device 81 fixing roll 811 heating mechanism 82 pressure roll 100 rotary developing unit 110Y, 110M, 110C, 110K developing device 111Y, 111M, 111C, 111K developing roll 112Y toner cartridge 120 casing unit 121, 122 developing device Support plate 123 Developing device support plate connecting member 123a Rotating shaft 124 Rotary developing unit rotating member 124a Gear portion 125 Frame 126 Stepping module 126a Rotating shaft 127 Transmission gear 131 Gear member 132 Gear member moving means 200 Rotary developing unit 200a Gear portion 201 Transmission gear 2 Image forming apparatus 300 Rotary developing unit 310Y, 310M, 310C, 310K Developing apparatus 311Y, 311M, 311C, 311K Developing roller 312Y Toner cartridge 320 Casing unit 321, 322 Developing device support plate 323 Developing device support plate connecting member 323a Rotating shaft 324 Rotary developing unit rotating member 324a Gear portion 324b Protruding portion 325 Frame 327 Transmission gear 331 Roller 332 Roller moving means 400 Rotary Developing unit 424 Rotary developing unit rotating member 424a Gear portion 424b Protruding portion 427 Transmission gear 431 Rubber roller 432 Shaft 4 32a fulcrum 433 spring 434 rubber roller moving means

Claims (10)

A developing device is provided opposite to the image carrier on which the electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with toner, and the electrostatic latent image formed on the image carrier is provided. A toner image is formed on the image carrier by developing the image using the developing device, and the toner image is finally transferred and fixed on a predetermined recording medium, thereby fixing toner on the recording medium. In an image forming apparatus for forming an image consisting of an image,
The developing device is
A plurality of developing members for developing the electrostatic latent image formed on the image carrier with toners of different colors are arranged in the circumferential direction, and the gear teeth are arranged in the circumferential direction. A rotating body that has a gear portion and rotates in the circumferential direction by transmitting a driving force to the gear portion and sequentially arranges the plurality of developing members at positions facing the image carrier;
A frame that rotatably supports the rotating body;
A transmission gear that is rotatably attached to the frame and meshes with the gear portion that transmits driving force to the gear portion, and the gear teeth are made of plastic.
The image forming apparatus according to claim 1, wherein the number of gear teeth is a non-integer multiple of the number of teeth of the transmission gear.   The gear portion satisfies a relationship in which a value obtained by dividing the number of gear teeth by the number of the plurality of developing members is a non-integer multiple of the number of teeth of the transmission gear. The image forming apparatus according to 1. An engaging member that is movable between an engaging position that engages with the rotating body and prevents the rotating body from rotating and a retracted position that is separated from the rotating body;
The image forming apparatus according to claim 1, further comprising a moving unit that moves the engagement member from the retracted position to the engagement position after the rotation of the rotating body is stopped.   The image forming apparatus according to claim 3, wherein the engagement member engages with a gear tooth of the gear portion at the engagement position to prevent the rotation of the rotating body.   The image forming apparatus according to claim 4, wherein the number of the gear teeth is an integral multiple of the number of the plurality of developing members.   The image forming apparatus according to claim 4, wherein the engagement member is a non-rotatable gear member that meshes with a gear tooth of the gear portion at the engagement position. A developing device is provided opposite to the image carrier on which the electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with toner, and the electrostatic latent image formed on the image carrier is provided. A toner image is formed on the image carrier by developing the image using the developing device, and the toner image is finally transferred and fixed on a predetermined recording medium, thereby fixing toner on the recording medium. In an image forming apparatus for forming an image consisting of an image,
The developing device is
A plurality of developing members for developing the electrostatic latent image formed on the image carrier with different color toners are arranged in a circumferential direction, and the rotation in the circumferential direction and the stop of the rotation are repeated. A rotating body that sequentially arranges the plurality of developing members at positions facing the image carrier by rotating and stopping in the circumferential direction;
A braking member that comes into contact with a predetermined part of the rotating body whose rotation speed has decreased due to rotation stoppage,
At least one of the predetermined portion and the braking member absorbs an inertial force that causes the rotating body to continue rotating in the circumferential direction when the braking member contacts the predetermined portion. An image forming apparatus.   At least one of the predetermined portion and the braking member is made of an elastic body, and absorbs the inertial force by elastically deforming when the braking member contacts the predetermined portion. 8. The image forming apparatus according to claim 7, wherein:   At least one of the braking member and the predetermined portion is a roller that is rotatably supported. When the braking member comes into contact with the predetermined portion, the inertial force is rotated by receiving the inertial force. The image forming apparatus according to claim 7, wherein the image forming apparatus absorbs light.   The braking member is configured to contact the predetermined portion via an elastic mechanism, and absorb the inertial force by elastically deforming the elastic mechanism when contacting the predetermined portion. The image forming apparatus according to claim 7.

Images