JP2851861B2 - Photosensitive drum, process cartridge having this photosensitive drum, and image forming apparatus to which this process cartridge is detachable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photosensitive drum used in an image forming apparatus such as a copying machine, a printer, and a facsimile, a process cartridge having the photosensitive drum, and a detachable process cartridge. The present invention relates to a simple image forming apparatus.

[Prior Art] Conventionally, a drum unit is composed of a photosensitive drum and flanges integrally fixed to both ends of the photosensitive drum. Further, one of the flanges is provided with a gear called an integral drum gear. The drum gear meshes with a gear called a drum drive gear, and drives the photosensitive drum by transmitting power from a power source such as a motor via various power transmission means. Some drum gears also mesh with a gear called a sleeve gear that rotates together with a developing sleed supported by a developing device, transmit power from the drum gear, and drive the developing sleeve.

Some drum gears use a helical gear so that the photosensitive drum rotates more smoothly. A force acts in the thrust direction depending on the direction of the torsion angle of the helical gear. Therefore, in the process cartridge, the photosensitive drum is held in the process cartridge housing with a small gap in order to rotate the photosensitive drum smoothly, and the photosensitive drum is moved to the reference position by the force in the thrust direction by the helical gear. The applicant of the present invention has disclosed a process cartridge and an image forming apparatus for moving and obtaining a high-quality image in Japanese Patent Application Laid-Open No. 63-4252.
Application by the Japanese Patent Publication No.

[Problem to be Solved by the Invention] The present invention is a further development of the above-mentioned conventional technology.

Means for Solving the Problems According to the present invention, in a photosensitive drum used in an image forming apparatus, a drive belt provided in an image forming apparatus main body fixed to one end of the photosensitive drum in a longitudinal direction is provided. A first helical gear for receiving a driving force for rotating the photoconductor drum from the gear teeth, and a first helical gear provided on the other end side of the photoconductor drum in a longitudinal direction, provided on an image forming apparatus main body. A second helical gear for transmitting a driving force to the transfer roller,
Wherein the first helical gear and the second helical gear have twisting directions opposite to each other, and when the photosensitive drum is used in the image forming apparatus, the photosensitive member A resultant force of a thrust force DI received by the rotation of the first helical gear on the drum and a thrust force D2 received as a reaction force of the thrust force T received by the transfer roller on the photosensitive drum.
D3, wherein D3 is configured to be larger than a maximum static friction force in a thrust direction generated between the photosensitive drum and the transfer roller.

According to another aspect of the present invention, in a process cartridge detachably mountable to the image forming apparatus main body, a, a drive gear provided on the image forming apparatus main body fixed to one end of the photosensitive drum in the longitudinal direction. A first helical gear for receiving a driving force for rotating the photosensitive drum, and a transfer roller provided on the main body of the image forming apparatus, which is fixed to the other end of the photosensitive drum in the longitudinal direction. A second helical gear for transmitting a driving force to the first helical gear and the second helical gear, wherein the twisting directions are opposite to each other, When the process cartridge is mounted on the image forming apparatus main body, a thrust force D1 received by the photosensitive drum by rotation of the first helical gear and a thrust force T received by the photosensitive drum by the transfer roller Sla received as a reaction force of A photosensitive drum configured such that a resultant force D3 of the photosensitive drum and a transfer force D2 is greater than a maximum static friction force in a thrust direction generated between the photosensitive drum and the transfer roller; b, the photosensitive drum And a process unit that acts on the process cartridge.

According to another aspect of the present invention, there is provided an image forming apparatus for detachably attaching a process cartridge to form an image on a transfer material, wherein a is provided on an image forming apparatus main body fixed to one end of the photosensitive drum in a longitudinal direction. A first helical gear for receiving a driving force for rotating the photosensitive drum from the driven helical gear, and an image forming apparatus fixed to the other end in the longitudinal direction of the photosensitive drum. A second helical gear for transmitting a driving force to a transfer roller provided in the apparatus body, wherein the first helical gear and the second helical gear have a twisting direction. The thrust force D1 received by the rotation of the first helical gear on the photosensitive drum when the process cartridge is mounted on the image forming apparatus main body is opposite to each other, and the photosensitive drum is Thrust force T received by the transfer roller Thrust force receive as a reaction force D2
And a process unit acting on the photosensitive drum, wherein the resultant force D3 of the photosensitive drum and the transfer roller is larger than the maximum static friction force in the thrust direction generated between the photosensitive drum and the transfer roller. And a mounting portion for removably mounting a process cartridge having:
b, a conveying means for conveying the transfer material.

Embodiment 1 FIG. 1 is a model diagram that best represents the features of the present invention, and will be described below. FIG. 1 shows a model around a photosensitive drum of a laser beam printer as an example of an image forming apparatus. The image forming method and the operation of the apparatus are the same as those of a known apparatus.

A first helical gear 1 integrated with the flange and a second helical gear 2 integrated with the flange are fixed to one end of the photosensitive drum 3. The directions of the torsion angles of the first and second helical gears are opposite to each other.

A drum drive gear 5 having a helical gear is fixed to the cored bar 4 to transmit power from a motor (not shown) to move the photosensitive drum 3 counterclockwise as viewed from the left side in FIG. Rotate. At this time, the photosensitive drum 3 is subjected to thrust force D ₁ to the left.

Next, the second helical gear 2 is rotated by the rotation of the photosensitive drum 3, and the third helical gear 2 is integrally fixed to the cored bar 6.
Power is transmitted to the helical gear 7 to rotate the second rotating body 8. At this time, the second rotating body 8 receives a thrust force T in the right direction, and the photosensitive drum 3 exerts a leftward force as a reaction force thereof.
Subject to D _2. That is, the force that the photosensitive drum 3 receives is
A resultant force D ₃ between D ₁ and the force D _2, in the present embodiment is the left direction. For example, when the second rotating body is a transfer roller in contact pressing the photosensitive drum 3, the force D ₃ than the maximum static frictional force in the thrust direction generated between the photosensitive drum 3 and the transfer roller 8 If the photosensitive drum 3 is set to be large, the photosensitive drum 3 can be moved to the reference plane, and the position of the photosensitive drum 3 in the longitudinal direction does not change when the photosensitive drum 3 is rotationally driven. Further, the transfer roller 8 is also fixed in the position in the thrust direction, and the transfer blur does not occur, so that a high quality image can be formed. In FIG. 1, the helical gear is urged to the left, but the helical gear can be urged in the opposite direction by reversing the direction of rotation or the direction of rotation.

If, first, when the second is given in the same direction in the direction of the helix angle of the helical gear, the thrust force D ₁ is the left direction, the reaction force D ₂ becomes the right direction, a force acts in a direction to cancel each other out .
In this case, the smaller the size of the resultant force D _3, there is also likely to be smaller than the maximum static friction force between the photosensitive drum 3 and the transfer roller 8, the photosensitive drum 3 can not be moved to the normal position. Also, for some reason, the thrust force D ₁ and the reaction force
When the magnitude of D ₂ largely varies, the direction of its action is also likely to vary, the thrust direction position of the photoreceptor drum 3 fluctuates.

The second rotating body 8 may be a developing sleeve, a charging roller, a cleaning roller, a stirring bar of a cleaner, or the like.

Further, even if the second helical gear 2 is further meshed with a sleeve gear, a charging roller gear, a cleaning gear, and the like, the direction of the thrust force acting on the photosensitive drum 3 is the same direction, so the effect is the same. good.

FIG. 4 is a cross-sectional view of a process cartridge and an image forming apparatus using the drum unit of the present invention when the second rotating body 8 is a transfer roller and a developing sleeve.
In this embodiment, the second helical gear 2 meshes with a transfer roller gear, a sleeve gear, a charging roller gear, and a gear for rotating a stirring bar of a cleaner. A video signal sent from a controller (not shown) is input to a laser scanning optical system unit 45. The unit includes a semiconductor laser, a collimator lens, a polygon mirror, an f-θ lens, a tilt correction lens, and the like. Then, the video signal is applied to the semiconductor laser, and the diverging laser light is collimated by a collimator lens, irradiated to a polygon mirror rotating at high speed, and the laser light is exposed via a reflecting mirror 46 to the exposure unit 31 of the photosensitive drum 30. Scan. At this time, in order to detect the timing at which the semiconductor laser scans the photosensitive surface of the photosensitive drum 30, that is, the timing at which the video signal is transmitted, the laser light is detected at a predetermined position before scanning the photosensitive surface of the photosensitive member 3 with the laser light. A beam detector (not shown) is provided, and sends a video signal in synchronization with the generated BD signal.

Around the photosensitive drum 3, a charging roller 33, an exposure unit 3
1. A developing device 34, a transfer roller 35, and a cleaner 36 are provided in order along the rotation direction. The process cartridge contains the photosensitive drum 3, the charging roller 33, the developing device 34, the cleaner 36, and the toner, and is detachable from the apparatus main body 100. The transfer material loaded on the cassette 37 is fed by a paper feed roller 38 according to a signal from a CPU (not shown), and the transfer timing to the transfer unit is controlled by a registration roller 39 to control the toner on the photoconductor 3. The image is transferred, fixed by a fixing roller 41 via a conveyance guide 40, and discharged to a paper discharge unit 44 via a conveyance guide 42 and a discharge roller 43.

Second Embodiment FIG. 2 is a model diagram showing a second embodiment of the present invention.
The same members as those in the first embodiment are denoted by the same symbols. This will be described below.

A first helical gear 1 integrated with the flange and a second helical gear 2 integrated with the flange are fixed to one end of the photosensitive drum 3. The directions of the torsion angles of the first and second helical gears are opposite to each other.

Further, a drum driving gear 15 having a helical gear and a first rotating body 10 is fixed to the cored bar 14 and transmits power from a motor (not shown) to move the photosensitive drum 3 to the position shown in FIG. Turn counterclockwise as viewed from the left. At this time, the photosensitive drum 3 is subjected to thrust force D ₁ to the left. Next, the second
The helical gear 2 is rotated by rotation of the photosensitive drum 3, and transmits power to a fourth helical gear 7 fixed integrally to the cored bar 6, and the second rotator 8 To rotate. Second rotating body 8 at this time is subjected to thrust force T in the right direction, the photosensitive drum 3 receives a force D ₂ to the left as a reaction force.
In other words, force the photosensitive drum 3 receives is force D ₃ of the force D ₁ and the force D _2, in the present embodiment is the left direction. For example, when the second rotating body 8 is a transfer roller that is in pressure contact with the photosensitive drum 3, the resultant force D _{3 is} smaller than the maximum static friction force in the thrust direction generated between the photosensitive drum 3 and the transfer roller 8.
Is set to be large, the photosensitive drum 3 can be moved to the reference plane, and the position of the photosensitive drum 3 in the longitudinal direction does not change when the photosensitive drum 3 is rotationally driven. . Further, the transfer roller 8 is also fixed in the position in the thrust direction, and the transfer blur does not occur, so that a high quality image can be formed. In FIG. 2, it is biased to the left,
If the direction of the helix angle of the helical gear or the direction of rotation is reversed, it can be urged in the opposite direction.

If, first, when the second is given in the same direction in the direction of the helix angle of the helical gear, the thrust force D ₁ is the left direction, the reaction force D ₂ becomes the right direction, a force acts in a direction to cancel each other out .
In this case, the smaller the size of the resultant force D _3, there is also likely to be smaller than the maximum static friction force between the photosensitive drum 3 and the transfer roller 8, you can not move to the position of the photosensitive drum 3 or regular. Also, for some reason, the thrust force D ₁ and the reaction force
When the magnitude of D ₂ largely varies, the direction of its action is also likely to vary, the thrust direction position of the photoreceptor drum 3 fluctuates.

In addition, the first rotating body 10 and the second rotating body 8 may be a transfer roller, a developing sleeve, a charging roller, a cleaning roller, a stirring bar of a cleaner, and the like, respectively.

Further, even if the second helical gear 2 is further meshed with a sleeve gear, a charging roller gear, a cleaning gear, and the like, the direction of the thrust force acting on the photosensitive drum 3 is the same direction, so the effect is the same. So good.

FIG. 4 is a cross-sectional view of a process cartridge and an image forming apparatus using the drum unit of the present invention when the first rotating body 10 is a transfer roller 35, the second rotating body 8 is a charging roller 33, and an image sleeve. FIG. In this embodiment, the first helical gear 1 meshes with the transfer roller gear, and the second helical gear 2 meshes with the sleeve gear, the charging roller gear, and the gear that rotates the stirring rod of the cleaner. A video signal sent from a controller (not shown) is input to a laser scanning optical system unit 45. The unit includes a semiconductor laser, a collimator lens, a polygon mirror, an f-θ lens, a tilt correction lens, and the like. Then, the video signal is applied to the semiconductor laser, and the generated laser light is collimated by a collimator lens, irradiated to a polygon mirror rotating at high speed, and the laser light is exposed via a reflection mirror 46 to an exposure unit 31 of the photosensitive drum 30. Scan. At this time, in order to detect the timing at which the semiconductor laser scans the photosensitive surface of the photosensitive drum 30, that is, the timing at which the video signal is transmitted, the laser light is detected at a predetermined position before scanning the photosensitive surface of the photosensitive member 3 with the laser light. A beam detector (not shown) is provided, and sends a video signal in synchronization with the generated BD signal.

Around the photosensitive drum 3, a charging roller 22, an exposure unit 3
1. A developing device 34, a transfer roller 35, and a cleaner 36 are provided in order along the rotation direction. The process cartridge contains the photosensitive drum 3, the charging roller 33, the developing device 34, the cleaner 36, and the toner, and is detachable from the apparatus main body 100. The transfer material loaded on the cassette 37 is fed by a paper feed roller 38 according to a signal from a CPU (not shown), and the transfer timing to the transfer unit is controlled by a registration roller 39 to control the toner on the photoconductor 3. The image is transferred, fixed by a fixing roller 41 via a conveyance guide 40, and discharged to a paper discharge unit 44 via a conveyance guide 42 and a paper discharge roller 43.

FIG. 5 is a side view of one embodiment of the process cartridge C, in which the second helical gear 2 is integrated with the photosensitive drum, the charging roller gear 57 integrated with the charging roller, and the developing roller. Sleeve gear 67 integrated with sleeve
And are engaged.

FIG. 6 is a side view as viewed from the opposite side of the process cartridge C. The first helical gear 1 is integrated with the photosensitive drum and also serves as a drum driving gear provided on the main body side. It is in mesh with the transfer roller gear 15.

Third Embodiment FIG. 3 is a model diagram showing a third embodiment of the present invention.
The same members as those of the second embodiment are denoted by the same symbols. This will be described below.

A first helical gear 1 integrated with the flange, a second helical gear 2 and a third helical gear 12 integrated with the flange are fixed to one end of the photosensitive drum 3. ing. The direction of the torsion angle of the helical gear in FIGS. 2 and 3 is the same, and is opposite to that of the first helical gear.

Further, a drum driving gear 15 having a helical gear and a first rotating body 10 is fixed to the cored bar 14 and transmits power from a motor (not shown) to move the photosensitive drum 3 to the position shown in FIG. Turn counterclockwise as viewed from the left. At this time, the photosensitive drum 3 is subjected to thrust force D ₁ to the left. Next, the second
The helical gear 2 is rotated by rotation of the photosensitive drum 3, and transmits power to a fourth helical gear 7 fixed integrally to the cored bar 6, and the second rotator 8 To rotate. Second rotating body 8 at this time is subjected to thrust force T in the right direction, the photosensitive drum 3 receives a force D ₂ to the left as a reaction force.
Further, the fourth helical gear meshes with a gear (not shown), and rotates a third rotating body (not shown) with the same configuration as the second rotating body. In this case the third rotating member receives thrust force T 'in the right direction, the photosensitive drum 3 receives a force D ₂ to the left as a reaction force. In other words, force the photosensitive drum 3 receives a force D _1, a resultant force D ₃ of the force D ₂ and a force D _2, in the present embodiment is the left direction. For example, when the second rotating body 8 is a charging roller that is in pressure contact with the photosensitive drum 3, the resultant force D _{3 is} smaller than the maximum static friction force in the thrust direction generated between the photosensitive drum 3 and the charging roller 8. Is set to be large, the photosensitive drum 3 can be moved to the reference plane, and the position of the photosensitive drum 3 in the longitudinal direction does not change when the photosensitive drum 3 is rotationally driven. . Also, the position of the charging roller 8 in the thrust direction is fixed. In FIG. 3, the urging is performed in the left direction. However, if the direction of rotation of the helical gear is reversed or the direction of rotation is reversed, the urging can be performed in the opposite direction.

If, first, second, if the third is given in which the direction of the helix angle of the helical gear in the same direction, the thrust force D ₁ is the left direction, the reaction force
D ₂ and D ₂ are in the right direction, and the force acts in a direction to cancel each other. In this case, the smaller the size of the resultant force D _3, there is also likely to be smaller than the maximum static friction force between the photosensitive drum 3 and the charging roller 8, the photosensitive drum 3 can not be moved to the normal position. Further, the thrust force D ₁ for some reason, if the magnitude of the reaction force D _2, D ₂ largely varies, the direction of its action is also likely to vary, the thrust direction position variation of the photosensitive drum 3 Resulting in.

Further, the first rotator 10, the second rotator 8, and the third rotator (not shown) may be a transfer roller, a developing sleeve, a charging roller, a cleaning roller, a stirring bar of a cleaner, or the like.

Further, the direction of the thrust force acting on the photosensitive drum 3 does not change even when the second helical gear 2 and the third helical gear 12 are further meshed with a sleeve gear, a charging roller gear, a cleaning gear, and the like. Since the direction is the same, the effect is the same, so it is good.

In this embodiment, three helical gears are used because the ratio of the peripheral speed between the photosensitive drum and the developing sleeve, the ratio between the peripheral speed between the photosensitive drum and the transfer roller, and the ratio between the photosensitive drum and the charging roller. In order to set the ratio of the peripheral speed of the photosensitive drum and the peripheral speed of the cleaning roller to a desired value, the drum gear and the teeth of the sleeve gear, the transfer roller gear, the charging roller gear, the cleaning roller gear, etc. Number, drum, developing sleeve, transfer roller, charging roller,
This is because, when the diameter of the cleaning roller or the like is set, the drum gear and the roller meshing therewith can be easily meshed with each other in a good state by changing the torsion angle without dislocation like a spur gear. .

For example, when the transfer roller 10 is not pressed against the photosensitive drum 3 when the first rotating body 10 is the transfer roller,
The radius of 35 is R ₀ , the radius of the portion of the transfer roller 35 that contacts the photosensitive drum 3 when pressed is R _T , the radius of the photosensitive drum 3 is R _D , the angular velocity of the transfer roller 35 is ω _T , Drum 3
When the angular velocity was omega _D, if the peripheral speed ratio of the photosensitive drum with respect to the peripheral speed of the transfer roller 35 and _{x, R D · ω D ·} x = R T · ω T ... (1) drum drive gear 15 gears are Z ₅ , and the number of teeth of drum gear 1 is Z
Assuming ₁₁ , R _D / Z ₁₁ · x = R _T / Z ₅ (2) Also, the reference pitch radius of the drum drive gear 15 is R ₅ , the reference pitch radius of the drum gear 1 is R ₁₁ , and the distance between the shafts When the distance is L and the backlash is δ, L = R _D + R _T (3) L = R ₅ + R ₁₁ + δ (4) The drum driving gear 15 and the drum gear 1 are selected so as to satisfy the above formula. . For example, when 3% faster than the peripheral speed of the drum peripheral speed of the transfer roller 10, (2) 30 mm the outer diameter of _{R D / Z 11 · 1.03 =} R T / Z 5 photoconductive drum 3 from the equation, the drum gear 3 The number of teeth 3
0, if the number of teeth of the drum drive gear 15 is 15, R _T = 7.725 mm from the equation (2), and the distance L between the axes is L = 22.72 from the equation (3).
Assuming that the distance is 5 mm and the gap δ is 0.15 mm, R ₅ + R ₁₁ = 22.575 mm from the equation (4).

In general, for a spur gear, if the module and the number of teeth are determined, the reference pitch circle radius is uniquely determined, but in the case of a helical gear, the reference pitch radius can be freely changed by changing the torsion angle β. Can be. Therefore, a helical gear is used for the drum drive gear 15 and the drum gear 1. In general,
Assuming that the number of teeth is Z and the module is m, the reference pitch circle diameter d _0s of the helical gear is d _0s = Z · m / cosβ. Thus, from the equation (4), L−δ = R ₅ + R ₁₁ = ( Z ₅ + Z ₁₁ ) · m / cos β / 2, and if the module is 1, β = 4.67 °. With the above, the specifications of the drum driving gear 15 and the drum gear 1 have been determined.

Of course, even if a spur gear is transposed, the outer diameter of the gear can be changed and the outer diameter of the transfer roller can be changed, but the transposition amount is limited by the module. Further, when the dislocation is in the plus direction, the tip of the tooth becomes thin, and the impact when the teeth mesh with each other is easily transmitted, which causes pitch unevenness. Next, in this embodiment, if a spur gear is applied, the drum gear 1 has a reference pitch diameter of 30 mm, and the drum drive gear 15 has a reference pitch diameter of 15 mm. now,
If R _T = 7.725 mm and the backlash is 0.15 mm, the displacement of the drum drive gear 15 is −0.0375, which is a minus displacement. In general, when the number of teeth is less than about 15 teeth, the negative root dislocation reduces the strength of the tooth bottom. In other words, it is known that the strength of the tooth bottom is increased by performing plus dislocation. Therefore, it is not desirable to perform minus dislocation, and it is necessary to increase the number of teeth, which limits the design range. A drum gear 1 may be translocate but, taking the structure to engage with the sleeve gear (not shown) rotates integrally with the developing sleeve drum gear 1 are not shown, (the reaction force in this case, the D ₃ on the drum opposite direction Although D ₄ acts, D ₃ >> if D ₄ is no problem.) peripheral speed of the sleeve, the drum gear 1 and for center distance between the sleeve gear is determined from the distance or the like between the sleeve surface and the drum surface In some cases, dislocations need to be applied. In general, the sleeve gear often has about 15 teeth, so that it is not preferable to perform the negative shift as described above, and it is also not preferable to perform the positive shift. In this regard, in the case of the helical gear, the diameter of the transfer roller can be freely changed by changing the torsion angle, so that the drum drive gear 15 and the drum gear 1 do not have to be displaced.

Further, if the module is reduced, the number of teeth can be increased without increasing the reference pitch circle radius. However, if the module is small, the strength of the teeth is weakened, and vibration is likely to occur.

The same is true for the second helical gear 2 and the third helical gear 2.
The same applies to the helical gear 12, and also the ratio of the peripheral speed of the photosensitive drum to the developing sleeve, the ratio of the peripheral speed of the photosensitive drum to the transfer roller, and the ratio of the peripheral speed of the photosensitive drum to the charging roller. And the peripheral speed ratio between the photosensitive drum and the cleaning roller are different from each other. If the diameters of the transfer roller, developing sleeve, charging roller, etc. are determined, the torsion angle of the helical gear, the module, etc. By changing the diameter of the pitch cylinder by changing the gear, the gears must be engaged. Therefore, helical gears having different torsion angles and modules are used.

The dimensions and the like used in this embodiment are merely examples, and various dimensions may be used as long as the effects of the present invention are satisfied.

As described above, in the image forming apparatus such as the photosensitive drum in the image forming apparatus, the process cartridge including the image carrier, and the drum unit or the image forming apparatus to which the process cartridge is mounted, By providing a plurality of helical gears that rotate integrally with the drum, the ratio of the peripheral speed of the photosensitive drum to the developing sleeve, the ratio of the peripheral speed of the photosensitive drum to the transfer roller, In order to set the ratio of the peripheral speed between the charging roller and the peripheral speed between the photosensitive drum and the cleaning roller to a desired value, the drum gear and the meshing therewith, sleeve gear, transfer roller gear, charging roller gear, cleaning When the number of teeth of the roller gear, etc., and the diameter of the drum, developing sleeve, transfer roller, charging roller, cleaning roller, etc. are set, a spur gear Even if the dislocation is not performed, the drum gear and the roller meshing therewith can be easily meshed with each other in a good state by changing the twist angle, so that the pitch unevenness can be reduced.

(2) The directions of the torsion angles of the plurality of helical gears are opposite to each other on the front side and the rear side with respect to the photosensitive drum. A transfer roller as a transfer device, a helical gear for receiving drive of the photosensitive drum is provided at one end of the photosensitive drum, and a transfer roller is driven at the other end. In the image forming apparatus provided with a helical gear having a twist angle in the opposite direction to the helical gear for receiving the drive of the photosensitive drum, since the thrust force acting on the photosensitive drum is in the same direction, The photosensitive drum and the process cartridge can be automatically moved to a reference position, and high-quality image formation can be performed.

(3) The use of a helical gear reduces pitch unevenness in the sub-scanning direction, which is remarkable in a laser beam printer.

[Effects of the Invention] As described above, according to the present invention, the photosensitive drum is driven from a helical gear provided on the main body of the image forming apparatus and fixed to one end of the photosensitive drum in the longitudinal direction. A first helical gear for receiving a driving force for rotating,
A second helical gear fixed to the other end of the photosensitive drum in the longitudinal direction for transmitting a driving force to a transfer roller provided in the image forming apparatus main body; The helical gear and the second helical gear have twisting directions opposite to each other, and when the photosensitive drum is used in the image forming apparatus, the photosensitive drum is The resultant force D3 of the thrust force D1 received by the rotation of the helical gear and the thrust force D2 received by the photosensitive drum as a reaction force of the thrust force T received by the transfer roller is a difference between the photosensitive drum and the transfer roller. Since it is configured to be larger than the maximum static friction force in the thrust direction generated therebetween, the photosensitive drum can be reliably moved to the reference surface by the thrust force generated by the rotation of the helical gear, and the photosensitive drum can be moved. Rotating drive When, it is possible to prevent the longitudinal position of the photosensitive drum is varied.

[Brief description of the drawings]

1 is a model diagram showing a first embodiment of the present invention, FIG. 2 is a model diagram of a second embodiment, FIG. 3 is a model diagram of a third embodiment, and FIG. 4 is an embodiment of an image forming apparatus. The sectional views shown in FIGS. 5 and 6 are side views of the process cartridge. 1 is a first helical gear, 2 is a second helical gear, 3 is a photosensitive drum, 8 is a second rotating body, and 10 is a first rotating body.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/00 556

Claims (3)

(57) [Claims] 1. A photosensitive drum used in an image forming apparatus, wherein the photosensitive drum is fixed to a longitudinal end of the photosensitive drum by a driving helical gear provided in an image forming apparatus main body. A first helical gear for receiving a driving force for rotating, and a driving force transmitted to a transfer roller provided on the image forming apparatus main body fixed to the other end of the photosensitive drum in the longitudinal direction. A second helical gear, and the first helical gear and the second helical gear have opposite twisting directions, and the photosensitive drum is When used in an image forming apparatus, the photosensitive drum receives a thrust force DI caused by rotation of the first helical gear.
And a resultant force D3 of the photosensitive drum and a thrust force D2 received as a reaction force of the thrust force T received by the transfer roller,
A photosensitive drum configured to be larger than a maximum static friction force in a thrust direction generated between the photosensitive drum and the transfer roller. 2. A process cartridge detachably mountable to an image forming apparatus main body, comprising: a) a drive gear provided on the image forming apparatus main body fixed to one end of a photosensitive drum in a longitudinal direction; A first helical gear for receiving a driving force for rotating the body drum; and a transfer roller provided on the image forming apparatus main body fixed to the other end of the photosensitive drum in the longitudinal direction. A second helical gear for transmitting a force, wherein the first helical gear and the second helical gear have twisting directions opposite to each other, and the process cartridge When the photoreceptor drum is mounted on the image forming apparatus main body, the thrust force D1 received by the rotation of the first helical gear on the photosensitive drum and the thrust force T received by the transfer roller on the photosensitive drum are opposite to each other. Thrust as force A photosensitive drum configured such that a resultant force D3 with D2 is larger than a maximum static frictional force in a thrust direction generated between the photosensitive drum and the transfer roller; b, acting on the photosensitive drum A process cartridge comprising: 3. An image forming apparatus for forming an image on a transfer material in which a process cartridge is detachably mountable, wherein a is provided on an image forming apparatus main body fixed to one end in a longitudinal direction of a photosensitive drum. A first helical gear for receiving a driving force for rotating the photosensitive drum from the driving helical gear; and an image forming apparatus main body fixedly mounted on the other end in the longitudinal direction of the photosensitive drum. And a second helical gear for transmitting a driving force to the transfer roller provided in the first helical gear and the first helical gear and the second helical gear have opposite twisting directions. And a thrust force D1 received by the rotation of the first helical gear on the photosensitive drum when the process cartridge is mounted on the main body of the image forming apparatus, and a transfer on the photosensitive drum when the transfer is performed. Of the thrust force T A photosensitive drum configured to have a resultant force D3 with a thrust force D2 received as a force greater than a maximum static friction force in a thrust direction generated between the photosensitive drum and the transfer roller; and An image forming apparatus, comprising: a mounting section for detachably mounting a process cartridge having a process unit acting on a drum; and b, a transport unit for transporting the transfer material.