JP6175373B2 - Image forming unit and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming unit and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copying machine, a facsimile machine, a multifunction machine, for example, a printer, an image forming unit, an LED head, a transfer roller, a fixing device, a paper cassette, and the like are arranged. The image forming unit includes a photosensitive drum, a charging roller, a developing roller, a developing blade, a toner supply roller, a cleaning blade, a toner cartridge, and the like as driving force transmission members.

  In the image forming unit, the surface of the photosensitive drum uniformly charged by the charging roller is exposed by the LED head to form an electrostatic latent image. The toner supplied from the toner cartridge to the main body of the image forming unit, that is, the image forming unit main body, is supplied to the developing roller by the toner supply roller, and is thinned on the developing roller by the developing blade. The toner on the developing roller is adhered to the electrostatic latent image on the photosensitive drum, and the electrostatic latent image is developed to form a toner image on the photosensitive drum.

  The paper fed out from the paper cassette is sent to a transfer portion formed between the photosensitive drum and the transfer roller, and after the toner image is transferred by the transfer roller in the transfer portion, it is sent to the fixing device, The fixing device fixes the toner image to form an image.

  By the way, the photosensitive drum functions as a driving force transmission member for transmitting a driving force, first and second drum gears are attached to both ends, receives rotation from the motor via the first drum gear, This is transmitted to a predetermined roller, for example, a transfer roller via the drum gear (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-84794

  In the conventional printer, in order to make the photosensitive drum function as a driving force transmission member, it is required to improve the image quality in the future.

  The present invention provides an image forming unit and an image forming apparatus capable of improving the image quality when the image carrier is caused to function as a driving force transmission member by solving the problems of the conventional printer. Objective.

  Therefore, in the image forming unit of the present invention, the driving force transmission member disposed rotatably, the first and second gears attached to the ends of the driving force transmission member, and the first A third gear that is meshed with the gear and transmits the rotation of the driving source to the driving force transmission member, and meshed with the second gear, and the rotation of the driving force transmission member is transmitted to the predetermined rotating member. And a fourth gear.

The number of teeth of the first and second gears is made different from each other.
A reinforcing portion is formed in a region set based on the phase difference of each tooth in the first and second gears.

  According to the present invention, in the image forming unit, the driving force transmission member disposed rotatably, the first and second gears attached to the ends of the driving force transmission member, and the first A third gear that is meshed with the gear and transmits the rotation of the driving source to the driving force transmission member, and meshed with the second gear, and the rotation of the driving force transmission member is transmitted to the predetermined rotating member. And a fourth gear.

The number of teeth of the first and second gears is made different from each other.
A reinforcing portion is formed in a region set based on the phase difference of each tooth in the first and second gears.

  In this case, when the first gear and the third gear are meshed, the second gear and the fourth gear are meshed, and the driving force is transmitted by the driving force transmission member, It is possible to prevent the vibration generated by the load fluctuation accompanying the meshing with the third gear and the vibration generated by the load fluctuation accompanying the meshing of the second gear and the fourth gear from being resonated.

  Therefore, the image quality can be improved.

  Further, since the reinforcing portion is formed in the region set based on the phase difference of each tooth in the first and second gears, the first gear and the third gear mesh with each other in the set region. Therefore, even if the second gear and the fourth gear are engaged with each other, it is possible to suppress the vibration from being amplified.

  Therefore, fluctuations in vibration can be suppressed in the rotation cycle of the driving force transmission member, so that it is possible to prevent unevenness in the image formed on the medium. As a result, the image quality can be sufficiently improved.

FIG. 3 is a first diagram illustrating a relationship between drum gears attached to the photosensitive drum in the first embodiment of the present invention. 1 is a conceptual diagram of a printer according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram of an image forming unit according to the first embodiment of the present invention. FIG. 2 is a perspective view of a main part of the image forming unit main body according to the first embodiment of the present invention. It is a principal part perspective view of the rotation transmission system in the 1st Embodiment of this invention. It is a 1st figure which shows the area | region where the phase difference of each drum gear in the 1st Embodiment of this invention is small. FIG. 5 is a second diagram showing the relationship between the drum gears attached to the photosensitive drum in the first embodiment of the present invention. It is a 2nd figure which shows the area | region where the phase difference of each drum gear in the 1st Embodiment of this invention is small. FIG. 3 is a first diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. FIG. 6 is a second diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. FIG. 6 is a third diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. FIG. 10 is a fourth diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. It is a 1st figure which shows the example of the 1st drum gear in the 1st Embodiment of this invention. It is a 1st figure which shows the example of the 2nd drum gear in the 1st Embodiment of this invention. It is a 2nd figure which shows the example of the 1st drum gear in the 1st Embodiment of this invention. It is a 2nd figure which shows the example of the 2nd drum gear in the 1st Embodiment of this invention. FIG. 10 is a fifth diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. It is a 6th figure which shows the example of the vibration generate | occur | produced in the photosensitive drum in the 1st Embodiment of this invention. It is a 1st figure which shows the other example of the 1st drum gear in the 2nd Embodiment of this invention. It is a 1st figure which shows the other example of the 2nd drum gear in the 2nd Embodiment of this invention. It is the 2nd figure showing other examples of the 1st drum gear in a 2nd embodiment of the present invention. It is a 2nd figure which shows the other example of the 2nd drum gear in the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a conceptual diagram of the printer according to the first embodiment of the present invention. FIG. 3 is a conceptual diagram of the image forming unit according to the first embodiment of the present invention.

  In the figure, 10 is a printer, Cs1 is a housing of the printer 10, 11 is an image forming unit, and the image forming unit 11 is an image carrier disposed rotatably in the direction of arrow A, and A photosensitive drum 32 is provided as a driving force transmission member and as a rotating body. Reference numeral 12 denotes an exposure apparatus that is disposed close to the image forming unit 11 and opposed to the photosensitive drum 32, and forms an electrostatic latent image as a latent image on the surface of the photosensitive drum 32. An LED head 13 is a paper cassette (tray) serving as a medium storage unit that is detachably disposed in the lower portion of the printer 10 with respect to the housing Cs1, and 15 is a paper feed roller. 15 feeds the paper P as the medium stored in the paper cassette 13 to the medium transport path Rt1.

  Reference numeral 16 denotes a transport roller pair as a first transport member disposed downstream of the paper feed roller 15 in the medium transport path Rt1, and reference numeral 17 denotes a transport roller pair downstream of the transport roller pair 16 in the medium transport path Rt1. A transfer roller 18 as a transfer member that is disposed to face the photoconductive drum 32 and transfers a toner image as a developer image formed on the photoconductive drum 32 onto the paper P; The fixing device is disposed on the downstream side of the transfer roller 17 and fixes the toner image transferred onto the paper P to form an image, and the fixing device 18 serves as a first fixing member. A fixing roller R1, a pressure roller R2 as a second fixing member, and the like are provided.

  Reference numeral 19 denotes a pair of conveyance rollers as a second conveyance member disposed on the downstream side of the fixing device 18 in the medium conveyance path Rt1, and 20 is disposed on the downstream side of the conveyance roller pair 19 in the medium conveyance path Rt1. The paper P on which the image is formed, which is a pair of discharged rollers, is discharged from the main body of the printer 10 by the discharge roller pair 20, that is, from the main body of the apparatus through the discharge port h1, and is stacked on the stacker 21. The

  The image forming unit 11 includes a main body of the image forming unit 11, that is, an image forming unit main body 11a, and a developer container that is detachably disposed on the image forming unit main body 11a above the image forming unit main body 11a. A toner storage container 101 serving as a section, and a waste toner storage container 102 serving as a waste developer container disposed detachably with respect to the image forming unit main body 11a below the toner storage container 101. The toner storage container 101 stores toner T as a developer for forming an image, and the waste toner storage container 102 stores waste toner εT as a waste developer collected after the image is formed. .

  The toner storage container 101 includes a housing portion casing Cs2 and a shutter 40 serving as an opening / closing member rotatably disposed with respect to the housing portion housing Cs2. An agitating member 23 for agitating the toner T is disposed so as to be rotatable in an arrow B direction opposite to the rotation direction (arrow A direction) of the photosensitive drum 32, and outside the shutter 40 in the housing portion casing Cs2. Further, an agitating member 24 for agitating the toner T outside the shutter 40 is disposed so as to be rotatable in the direction of arrow C, which is the same direction as the direction of rotation of the photosensitive drum 32.

  The stirring member 23 includes a shaft portion sh1, and a resin-made thin plate pt1 as a flexible stirring element attached to the shaft portion sh1, and the stirring member 24 includes a shaft portion sh2, and A thin plate plate pt2 made of resin as a flexible stirring element is attached to the shaft portion sh2, and each plate pt1, pt2 is in a curved state as the stirring members 23, 24 rotate. The toner T is rotated and agitated.

  Further, in order to supply the toner T in the toner storage container 101 into the image forming unit main body 11a, an opening m1 in the shutter 40, an opening m2 in the housing casing Cs2, and a unit housing of the image forming unit main body 11a. A toner supply port m3 as a developer supply port is formed in the body Cs3. When the openings m1 and m2 are communicated with the rotation of the shutter 40, the toner T is supplied into the image forming unit main body 11a through the openings m1 and m2 and the toner supply port m3.

  In the image forming unit main body 11a, a charging roller 33 as a charging device that is brought into contact with the photosensitive drum 32 and uniformly charges the surface of the photosensitive drum 32, and the toner T are supplied with the electrostatic latent image. A developing roller 34 as a developer carrying member that forms a toner image by adhering to the image is rotatably disposed, and the charging roller 33 is in the direction of arrow D, which is opposite to the rotation direction of the photosensitive drum 32, in the developing roller direction. 34 is rotated in the direction of arrow E which is the opposite direction to the rotation direction of the photosensitive drum 32.

  Further, a toner supply roller 35 as a first developer supply member is brought into contact with the developing roller 34, and a toner supply roller 36 as a second developer supply member is provided below the toner supply roller 35. The toner supply roller 35 is arranged in the direction of arrow F, which is the same direction as the rotation direction of the developing roller 34, and the toner supply roller 36 is arranged in the direction of arrow G, which is the same direction as the rotation direction of the developing roller 34. The toner T rotated and supplied into the image forming unit main body 11 a is supplied to the developing roller 34. Above the developing roller 34, a developing blade 37 as a developer regulating member for thinning the toner T supplied to the developing roller 34 is disposed with its tip abutting against the developing roller 34. Is done.

  Further, the stirring members 105 and 106 are disposed below the toner supply port m3 in the image forming unit main body 11a, and the stirring members 107 are adjacent to the developing roller 34 and the toner supply roller 35, respectively. Adjacent agitating members 108 are rotatably arranged to agitate the toner T supplied into the image forming unit main body 11a.

  The stirring member 106 is disposed at a predetermined position above the developing roller 34 and the toner supply roller 35, and functions as a toner remaining amount detecting member that detects the remaining amount of toner T in the image forming unit main body 11a. For this purpose, the agitating member 106 is rotated in accordance with the rotation of a rotating shaft (not shown), and when it reaches the uppermost end of the rotation locus, it is dropped and rotated to the surface of the toner T by gravity preceding the rotating shaft. A rotating member is provided, and the remaining amount of toner T is detected based on the position of the rotating member.

  Reference numeral 110 denotes a cleaning device. The cleaning device 110 is held by the holding portion 111 and the holding portion 111, and a cleaning blade as a cleaning member disposed with its tip abutting against the photosensitive drum 32. The cleaning blade 112 scrapes and removes the toner T remaining on the photosensitive drum 32 after the toner image is transferred in accordance with the rotation of the photosensitive drum 32. The removed toner T is collected as waste toner εT, and is transported by the waste toner transport member 113 and supplied to the waste toner storage container 102.

  Next, the operation of the printer 10 will be described.

  First, when the paper feed roller 15 is rotated based on a print command from a control unit (not shown), the paper P stored in the paper cassette 13 is separated one by one and fed out to the medium transport path Rt1. The fed paper P is transported by the transport roller pair 16 and sent to a transfer portion between the photosensitive drum 32 and the transfer roller 17.

  In the image forming unit 11, the surface of the photosensitive drum 32 is uniformly charged by the charging roller 33 and exposed by the LED head 12 to form an electrostatic latent image. The toner T supplied from the toner storage container 101 into the image forming unit main body 11a is supplied to the developing roller 34 by the toner supply rollers 35 and 36, and is attached to the photosensitive drum 32 by the developing roller 34. The electrostatic latent image is developed to form a toner image. At this time, the toner T in the image forming unit main body 11a is stirred by the stirring members 105 to 108.

  Then, the toner image on the photosensitive drum 32 is transferred onto the paper P by the transfer roller 17 in the transfer portion. The toner T remaining on the surface of the photosensitive drum 32 after the transfer is removed by the cleaning blade 112, recovered as waste toner εT, and supplied to the waste toner storage container 102.

  Subsequently, the paper P is sent to the fixing device 18 where the toner image is fixed. In this way, the paper P on which an image is formed is transported by the transport roller pair 19, discharged to the outside of the apparatus main body by the discharge roller pair 20, and stacked on the stacker 21.

  Next, the rotation of a motor (drum motor) (not shown) as a driving source is transmitted to each rotating body such as the photosensitive drum 32, the charging roller 33, the developing roller 34, the toner supply rollers 35 and 36, and the transfer roller 17. The rotation transmission system will be described.

  FIG. 1 is a first diagram showing the relationship between drum gears attached to the photosensitive drum in the first embodiment of the present invention, and FIG. 4 is a schematic diagram of the main body of the image forming unit in the first embodiment of the present invention. FIG. 5 is a perspective view of a main part of the rotation transmission system in the first embodiment of the present invention, and FIG. 6 is a diagram showing a region where the phase difference of each drum gear is small in the first embodiment of the present invention. FIG. 1 is a second view showing the relationship of each drum gear attached to the photosensitive drum in the first embodiment of the present invention. FIG. 8 is a diagram showing each drum gear in the first embodiment of the present invention. It is a 2nd figure which shows the area | region where phase difference of this is small.

  In the figure, 11a is an image forming unit main body, m3 is a toner supply port, FL is a side frame disposed on the left side when viewed from the front of the printer 10 (FIG. 2), and FR is disposed on the right side when viewed from the front of the printer 10. A photosensitive drum 32, a charging roller 33, a developing roller 34, and the like are rotatably installed between the side frames FL and FR. Further, the cleaning device 110 extends between the side frames FL and FR.

  The photosensitive drum 32 includes a metal cylinder having a hollow cylindrical shape, a charge generation layer formed by applying a photosensitive solution to the cylinder, and hole transport on the charge generation layer. A charge transport layer formed by applying a solution containing a substance is provided.

  By the way, the photosensitive drum 32 receives the driving force input from one end of the photosensitive drum 32, in this embodiment, from the end on the side frame FL side, to the other end of the photosensitive drum 32. In, it functions as a driving force transmission member that transmits to the end on the side frame FR side.

  For this purpose, a first drum gear g1 as a first gear is provided at the end of the photoconductor drum 32 on the side frame FL side, and a second gear as a second gear is provided at the end of the photoconductor drum 32 on the side frame FR side. Two drum gears g2 are attached by press-fitting. Then, the first drum gear g1 is engaged with a driving side gear g3 as a third gear for transmitting the rotation of the motor to the photosensitive drum 32, and the second drum gear g2 and the photosensitive member are engaged. The rotation of the drum 32 is meshed with a predetermined rotating member, in this embodiment, a driven gear g4 as a fourth gear for transmitting to the transfer roller 17.

  Further, in order to transmit the rotation of the motor to the developing roller 34, the first drum gear g1 and the developing roller gear g5 as the fifth gear are meshed with each other.

  By the way, if the number of teeth of the first and second drum gears g1 and g2, that is, the number of teeth is equal, the phase of each tooth of the first drum gear g1 (FIG. 1) and the second drum gear g2 When the phase of each tooth is 180 [°] and the crest of each tooth of the first drum gear g1 coincides with the trough of each tooth of the second drum gear g2, the first drum gear g1 and the driving side gear When the second drum gear g2 and the driven gear g4 are meshed with each other and the driving force is transmitted by the photosensitive drum 32, the load fluctuation accompanying the meshing between the first drum gear g1 and the driving gear g3 is engaged. And the vibration generated by the load fluctuation accompanying the meshing of the second drum gear g2 and the driven gear g4 are offset, and no vibration is generated in the photosensitive drum 32.

  On the other hand, the phase of each tooth of the first drum gear g1 and the phase of each tooth of the second drum gear g2 are different by an angle other than 180 [°], and the tooth crests of the first drum gear g1 When the valleys of the teeth of the second drum gear g2 do not coincide with each other, the first drum gear g1 and the driving side gear g3 are meshed, and the second drum gear g2 and the driven side gear g4 are meshed with each other. When the driving force is transmitted by the drum 32, the vibration caused by the load fluctuation accompanying the meshing of the first drum gear g1 and the driving gear g3 and the load fluctuation accompanying the meshing of the second drum gear g2 and the driven gear g4. The generated vibration is resonated, and a large vibration is generated in the photosensitive drum 32.

  As a result, the image quality is degraded.

  Therefore, in the present embodiment, the diameter r1 of the first drum gear g1 is made larger than the diameter r2 of the second drum gear g2, the number of teeth of the first drum gear g1 is Z1, and the number of teeth of the second drum gear g2. When Z2 is Z2, the numbers of teeth Z1 and Z2 are made different from each other.

That is, the number of teeth of one of the first and second drum gears g1 and g2 is made larger than the number of teeth of the other, and in this embodiment,
Z1> Z2
To be.

  Therefore, when the first drum gear g1 and the driving side gear g3 are engaged, the second drum gear g2 and the driven side gear g4 are engaged, and the driving force is transmitted by the photosensitive drum 32, the first drum gear is transmitted. Preventing the vibration generated by the load fluctuation accompanying the meshing of g1 and the drive side gear g3 and the vibration generated by the load fluctuation accompanying the meshing of the second drum gear g2 and the driven gear g4 from being resonated. Therefore, it is possible to prevent a large vibration from being generated in the photosensitive drum 32. As a result, the image quality can be improved.

  However, if the number of teeth Z1 and Z2 is varied, unevenness (jitter) occurs in the image formed on the paper, and the image quality cannot be sufficiently improved.

Here, for example, as shown in FIG. 1, the number of teeth Z1 and Z2 is
Z1 = 20
Z2 = 18
In this case, the difference ΔZ between the number of teeth Z1 and Z2 is 2.

  Further, a predetermined tooth among the respective teeth of the first drum gear g1, for example, as shown in FIG. 1, a peak phase of the tooth th1, and a predetermined tooth among the respective teeth of the second drum gear g2, For example, when the phase of the tooth th2 peak coincides in the circumferential direction, as shown in FIG. 6, the phase of each tooth peak of the first drum gear g1 and the tooth peak of the second drum gear g2 The difference from the phase, that is, the phase difference is a predetermined value in the positive direction (rotational direction of the photosensitive drum 32) and the negative direction (opposite to the rotational direction of the photosensitive drum 32) in the circumferential direction. In this embodiment, a region Ari (i = 1, 2) that is 10 [°] or less is set (formed). Each region Ari is set at an equal pitch in the circumferential direction of the first and second drum gears g1 and g2, that is, at a pitch of 180 [°].

Further, as shown in FIG. 7, the number of teeth Z1, Z2 is
Z1 = 20
Z2 = 17
In this case, the difference ΔZ between the number of teeth Z1 and Z2 is 3.

  At this time, a predetermined tooth among the teeth of the first drum gear g1, for example, as shown in FIG. 7, a phase of the crest of the tooth th1 and a predetermined tooth among the respective teeth of the second drum gear g2. For example, when the phase of the crest of the tooth th2 coincides in the circumferential direction, as shown in FIG. 8, the phase of the crest of each tooth of the first drum gear g1 and the crest of each tooth of the second drum gear g2 A region Ari (i = 1, 2, 3) is set (formed) in which the phase difference from the first phase is 10 [°] or less in the + direction and the − direction in the circumferential direction. Each area Ari is set at an equal pitch in the circumferential direction of the first and second drum gears g1 and g2, that is, at a pitch of 120 [°].

  Thus, if the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 are different from each other, each tooth of the first drum gear g1 has a number of areas Ari equal to the difference ΔZ between the number of teeth Z1 and Z2. The phase difference between the peak phase and the peak phase of each tooth of the second drum gear g2 is reduced to 10 ° or less. The region Ari where the phase difference is 10 [°] or less is set at a pitch of an angle obtained by dividing 360 [°] by the difference ΔZ between the number of teeth Z1 and Z2.

  Next, the vibration generated in the photosensitive drum 32 when the first drum gear g1 and the driving side gear g3 are engaged and the second drum gear g2 and the driven side gear g4 are engaged to drive the motor. explain.

  FIG. 9 is a first diagram illustrating an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention. FIG. 10 is a diagram illustrating vibration generated in the photosensitive drum according to the first embodiment of the present invention. FIG. 11 is a third diagram showing an example of vibration generated in the photosensitive drum according to the first embodiment of the present invention, and FIG. 12 is a diagram according to the first embodiment of the present invention. FIG. 10 is a fourth diagram illustrating an example of vibration generated in the photosensitive drum. 9 to 12, the horizontal axis represents time t, and the vertical axis represents vibration amplitude.

  Temporarily, the phase of each tooth of the first drum gear g1 (FIG. 1) and the phase of each tooth of the second drum gear g2 are different by 180 [°], and each tooth peak of the first drum gear g1 The first drum gear g1 and the driving side gear g3 are engaged with each other and the second drum gear g2 and the driven side gear g4 are engaged with each other when the troughs of the respective teeth of the drum gear g2 match. When the driving force is transmitted through the first drum gear g1 and the driving side gear g3, the load fluctuation accompanying the meshing of the first drum gear g1 causes the vibration of the waveform shown by the line L1 in FIG. 9 to generate the second drum gear g2 and the driven side gear. Due to the load fluctuation accompanying the meshing with g4, the vibration of the waveform shown by the line L2 in FIG. 9 is generated. In this case, since the phase of the waveform indicated by the line L1 and the phase of the waveform indicated by the line L2 are different from each other by 180 [°], the vibration is canceled and the photosensitive drum 32 is indicated by the line L3 in FIG. In this case, no vibration occurs.

  Further, it is assumed that the phase of each tooth of the first drum gear g1 is the same as the phase of each tooth of the second drum gear g2, and that the crest of each tooth of the first drum gear g1 and the second drum gear g2 When the crests of the teeth coincide with each other, the first drum gear g1 and the driving side gear g3 are engaged, the second drum gear g2 and the driven side gear g4 are engaged, and the driving force is applied by the photosensitive drum 32. When transmitted, the load fluctuation accompanying the meshing of the first drum gear g1 and the driving side gear g3 causes the vibration of the waveform shown by the line L11 in FIG. 10, and the meshing of the second drum gear g2 and the driven side gear g4. Due to the load fluctuation accompanying the vibration of the waveform shown by the line L12 in FIG. In this case, since the phase of the waveform indicated by the line L11 is the same as the phase of the waveform indicated by the line L12, the vibration is amplified and a large amount is generated in the photosensitive drum 32 as indicated by the line L13 in FIG. Vibration occurs.

  In the present embodiment, as described above, since the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 is different, the number of areas Ari is equal to the difference ΔZ between the number of teeth Z1 and Z2. The phase difference between the phase of each tooth crest of the first drum gear g1 and the phase of each tooth crest of the second drum gear g2 is reduced to 10 ° or less.

Therefore, the number of teeth Z1 is
Z1 = 20
The first drum gear g1 and the drive side gear g3 are meshed, and the number of teeth Z2 is
Z2 = 18
When the second drum gear g2 and the driven gear g4 are meshed and the driving force is transmitted by the photosensitive drum 32, the load fluctuation caused by the meshing of the first drum gear g1 and the driving gear g3 When the vibration having the waveform indicated by the line L21 in FIG. 11 occurs and the vibration having the waveform indicated by the line L22 in FIG. 11 is generated due to the load fluctuation accompanying the meshing of the second drum gear g2 and the driven gear g4, FIG. 11, in the photosensitive drum 32, the vibration is amplified and the amplitude is increased in the regions Ar <b> 1 and Ar <b> 2 where the phase difference is 10 ° or less, and the vibration is canceled out in the other regions. The amplitude is reduced.

The number of teeth Z1 is
Z1 = 20
The first drum gear g1 and the drive side gear g3 are meshed, and the number of teeth Z2 is
Z2 = 17
When the second drum gear g2 and the driven gear g4 are meshed and the driving force is transmitted by the photosensitive drum 32, the load fluctuation caused by the meshing of the first drum gear g1 and the driving gear g3 When the vibration having the waveform indicated by the line L31 in FIG. 12 occurs and the vibration having the waveform indicated by the line L32 in FIG. 12 occurs due to the load fluctuation accompanying the meshing of the second drum gear g2 and the driven gear g4, FIG. As indicated by a line L33 of FIG. 12, in the photosensitive drum 32, the vibration is amplified and the amplitude is increased in the regions Ar1 to Ar3 where the phase difference is 10 [°] or less, and the vibration is canceled in the other regions. The amplitude is reduced.

  Therefore, the photosensitive drum 32 cannot be stably rotated, and vibrations with periodically varying amplitudes are generated in the photosensitive drum 32, resulting in uneven density (jitter) in the image formed on the paper P. End up. As a result, the image quality cannot be sufficiently improved.

  Therefore, in the present embodiment, the photosensitive drum 32 is rotated stably by increasing the strength of the area Ari where the phase difference between the first and second drum gears g1 and g2 is 10 [°] or less. I am doing so.

  FIG. 13 is a first diagram showing an example of the first drum gear in the first embodiment of the present invention, and FIG. 14 is a first diagram showing an example of the second drum gear in the first embodiment of the present invention. FIG. 15 is a second diagram showing an example of the first drum gear in the first embodiment of the present invention, and FIG. 16 is a diagram showing an example of the second drum gear in the first embodiment of the present invention. FIG.

  In the drawing, g1 is a first drum gear, g2 is a second drum gear, 51 is a hole for passing a shaft (not shown) as a rotation shaft of the first and second drum gears g1 and g2, and 52 is a hole of the hole 51. It is the cyclic | annular boss | hub part formed in the circumference | surroundings.

The number of teeth Z1, Z2 of the first and second drum gears g1, g2 is
Z1 = 20
Z2 = 18
13 and 14, as shown in FIGS. 13 and 14, predetermined positions in the regions Ar <b> 1 and Ar <b> 2 (FIG. 6) where the phase difference of each tooth is 10 [°] or less, in the present embodiment, the region Ar <b> 1. , Th2 reinforcing ribs Rb1 and Rb2 serving as reinforcing portions extending from the vicinity of the central teeth Ts1 and Ts2 having the smallest phase difference among the teeth in Ar2 toward the boss portion 52, that is, in the radial direction. Is formed.

The number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 is
Z1 = 20
Z2 = 17
15 and 16, as shown in FIGS. 15 and 16, in a predetermined place in the regions Ar <b> 1 to Ar <b> 3 (FIG. 8) where the phase difference of each tooth is 10 ° or less, in the present embodiment, the region Ar <b> 1. The reinforcing ribs Rb1 and Rb2 are formed by extending from the vicinity of the central teeth Ts1 and Ts2 having the smallest phase difference among the teeth in .about.Ar3 toward the boss portion 52.

  Next, when the reinforcing ribs Rb1 and Rb2 are not formed on the first and second drum gears g1 and g2, the vibration generated on the photosensitive drum 32, and the reinforcing ribs Rb1 and Rb2 on the first and second drum gears g1 and g2, respectively. A description will be given of the vibration generated in the photoconductive drum 32 when the above is formed.

  FIG. 17 is a fifth diagram showing an example of vibration generated in the photosensitive drum in the first embodiment of the present invention, and FIG. 18 is a diagram of vibration generated in the photosensitive drum in the first embodiment of the present invention. It is a 6th figure which shows an example. 17 and 18, the horizontal axis represents time t, and the vertical axis represents vibration amplitude.

In FIG. 17, the line L23 indicates that the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 is
Z1 = 20
Z2 = 17
The waveform of vibration generated in the photosensitive drum 32 when the reinforcing ribs Rb1 and Rb2 are not formed on the first and second drum gears g1 and g2 is shown, and the maximum amplitude of the vibration at this time is w23.

In FIG. 17, the line L24 indicates that the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 is
Z1 = 20
Z2 = 17
The waveform of vibration generated in the photosensitive drum 32 when the reinforcing ribs Rb1 and Rb2 are formed on the first and second drum gears g1 and g2 is shown, and the maximum amplitude of the vibration at this time is w24.

In FIG. 18, the line L33 indicates the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2.
Z1 = 20
Z2 = 18
The waveform of vibration generated on the photosensitive drum 32 when the reinforcing ribs Rb1 and Rb2 are not formed on the first and second drum gears g1 and g2 is shown, and the maximum amplitude of the vibration at this time is w33.

In FIG. 18, the line L34 indicates that the number of teeth Z1 and Z2 of the first and second drum gears g1 and g2 is
Z1 = 20
Z2 = 18
The waveform of the vibration generated in the photosensitive drum 32 when the reinforcing ribs Rb1 and Rb2 are formed on the first and second drum gears g1 and g2 is shown, and the maximum amplitude of the vibration at this time is w34.

  Thus, in the present embodiment, since the reinforcing ribs Rb1 and Rb2 are formed in the area Ari in the first and second drum gears g1 and g2, the first drum gear g1 and the driving side gear g3 are formed in the area Ari. (FIG. 5) is engaged, and even when the second drum gear g2 and the driven gear g4 are engaged, it is possible to suppress the vibration from being amplified.

  Therefore, it is possible to suppress fluctuations in the vibration in the rotation cycle of the photosensitive drum 32, so that it is possible to prevent unevenness in the image formed on the paper P from occurring. As a result, the image quality can be sufficiently improved.

  By the way, in the present embodiment, thick reinforcing ribs Rb1 and Rb2 are formed on the first and second drum gears g1 and g2, but other portions are thinned by forming the reinforcing ribs Rb1 and Rb2. can do.

  Accordingly, a second embodiment of the present invention in which predetermined portions of the first and second drum gears g1 and g2 are thinned will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 19 is a first diagram showing another example of the first drum gear according to the second embodiment of the present invention, and FIG. 20 is another example of the second drum gear according to the second embodiment of the present invention. FIG. 21 is a second diagram showing another example of the first drum gear according to the second embodiment of the present invention, and FIG. 22 is a second diagram according to the second embodiment of the present invention. It is a 2nd figure which shows the other example of a drum gear.

  In the figure, g1 is a first drum gear as a first gear, g2 is a second drum gear as a second gear, Ts1 and Ts2 are central teeth having the smallest phase difference among teeth in the region Ari, Rb1 and Rb2 are reinforcing ribs as reinforcing portions, 51 is a hole for passing a shaft as a rotating shaft of the first and second drum gears g1 and g2, and 52 is an annular boss formed around the hole 51. Part.

  In this case, a portion between the ribs Rb1 and Rb2 in the circumferential direction, that is, a portion where the ribs Rb1 and Rb2 are not formed is thinned to form a meat stealing portion 53 having a fan-like shape, whereby the reinforcing ribs Rb1 and Rb2 are formed. Is spoken.

  Therefore, it is possible to prevent the first and second drum gears g1 and g2 from becoming heavy, and by forming the reinforcing ribs Rb1 and Rb2, it is possible to reduce the load applied to the motor as the drive source.

  In the present embodiment, the stealing portion 53 is formed in the portion where the ribs Rb1 and Rb2 are not formed, but a thin portion having an arc shape can be formed.

  In each of the embodiments described above, the reinforcing ribs Rb1 and Rb2 are formed for each region Ari where the phase difference between the teeth is 10 [°] or less, so the number of the reinforcing ribs Rb1 and Rb2 is the first and second. Is equal to the difference ΔZ between the number of teeth Z1 and Z2 of the drum gears g1 and g2, but the number of the reinforcing ribs Rb1 and Rb2 can be made larger than the difference ΔZ.

  In each of the above embodiments, the number of teeth Z1 of the first drum gear g1 is larger than the number of teeth Z2 of the second drum gear g2, but the number of teeth Z2 of the second drum gear g2 is set to the first number. It can be made larger than the number of teeth Z1 of the drum gear g1.

  In each of the embodiments, the reinforcing ribs Rb1 and Rb2 are formed in the region Ari where the phase difference is 10 ° or less in the + direction and the − direction in the circumferential direction. Since the region where vibration is likely to be amplified differs depending on the specifications of the gear, the angle of the phase difference range can be changed. In addition, a region where vibration is likely to be amplified can be set based on experiments.

  Furthermore, in each of the above-described embodiments, the first and second drum gears g1 are provided at both ends of the photosensitive drum 32 (FIG. 2) as an image carrier, as a driving force transmission member, and as a rotating body. , G2 are attached, but other rollers such as a transfer roller 17 as a transfer member and a developing roller 34 as a developer carrier function as a driving force transmission member, and gears are provided at both ends of the roller. Can be attached.

  In each of the embodiments, the first and second drum gears g1 and g2 are attached to both ends of the photosensitive drum 32. However, the first and second drum gears 32 are attached to one end of the photosensitive drum 32. The drum gears g1 and g2 can be attached as large gears and small gears of stepped gears.

  In each of the above embodiments, a monochrome printer having one image forming unit 11 has been described. However, the present invention can be applied to a color printer having a plurality of image forming units 11. The present invention can be applied to an image forming apparatus such as a copying machine, a facsimile machine, and a multifunction machine.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

11 Image forming unit 17 Transfer roller 32 Photosensitive drums g1, g2 First and second drum gears g3 Drive side gear g4 Driven side gear

Claims (7)

(A) a driving force transmission member disposed rotatably;
(B) first and second gears attached to the end of the driving force transmission member;
(C) a third gear meshed with the first gear for transmitting the rotation of the driving source to the driving force transmitting member;
(D) having a fourth gear meshed with the second gear and transmitting the rotation of the driving force transmitting member to a predetermined rotating member;
(E) the number of teeth of the first and second gears is different from each other ;
(F) the first and image-forming unit in the second gear, and wherein the Rukoto reinforcing portion is formed in a region that is set based on the phase difference of each tooth. Before SL region, the image forming unit according to claim 1 wherein the phase difference is an area below the predetermined value. The region includes a first image forming unit according to claim 1 or 2 is set at an equal pitch to the number equal to the number of teeth of the difference between the second gear. It said reinforcing portion is an image forming unit according to any one of claims 1 to 3 is a reinforcing rib formed by extending radially. The image forming unit according to claim 4 , wherein the reinforcing rib is formed to extend in a radial direction from a central tooth in each region. The image forming unit according to claim 4, wherein a meat stealing portion is formed between the reinforcing ribs in a circumferential direction. An image forming apparatus on which the image forming unit according to any one of claims 1 to 6 is mounted.

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