JP3078465B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer having a photosensitive drum with an internal gear.

[0002]

2. Description of the Related Art As a conventional image forming apparatus such as a copying machine, there is an image forming apparatus having a cylindrical photosensitive drum 51 as shown in FIG. In this image forming apparatus, the photosensitive drum 51
Is charged by a main charger 52, the photosensitive drum 51 is exposed to light emitted from an exposure device 53, and an electrostatic latent image obtained by the exposure is developed by a developing device 54. The agent image is transferred onto a sheet by a transfer charger 55. The surface of the photoreceptor after the transfer is removed by a cleaning blade (not shown) of the cleaning device 56, and the developer image on the paper is fixed on the paper by the fixing device 57. During such an image forming operation, the photosensitive drum 51 is driven to rotate in one direction by a driving device.

The above-mentioned driving device for the photosensitive drum is disclosed in JP-A-58-120265 and JP-A-61-1558.
As disclosed in Japanese Patent No. 63, there is proposed a system in which an internal gear is provided on a photosensitive drum and the photosensitive drum is rotated by a small-diameter drive gear meshing with the internal gear (hereinafter, referred to as an internal gear system). ing. In such a configuration, the number of meshing teeth between the drive gear and the passive gear, that is, the internal gear is increased as compared with a configuration in which an external gear is provided on the photosensitive drum and the drive gear is meshed with the external gear. There is an advantage that drive unevenness affected by the drive pitch is unlikely to occur. Further, since the drive gears and the like can be arranged inside the photosensitive drum, there is an advantage that the drive device can be downsized and the image forming apparatus can be downsized accordingly.

[0004]

However, around the cylindrical photosensitive drum, the main charger 52, the exposure device 53, the developing device 54, the transfer charger 55, and the cleaning device for performing the image forming process. Process elements such as 56 are disposed, of which, for example, the cleaning blades of the developing device 54 and the cleaning device 56
The photosensitive drum 51 is pressed against the photosensitive drum 51 to apply a pressing force to the photosensitive drum 51. For this reason, the photosensitive drum 51 is slightly bent, displaced, or decentered. On the other hand, in the internal gear system, as described above, the number of meshing teeth between the drive gear and the passive gear, that is, the internal gear is large. Therefore, torque unevenness occurs depending on the positional relationship between the process element pressed into contact with the photosensitive drum 51 and the driving gear and the like, and the driving gear cannot rotate the internal gear, that is, the photosensitive drum 51 smoothly. For this reason, there arises a problem that an image defect occurs due to uneven rotation of the photosensitive drum 51. And, the above-mentioned Japanese Patent Application Laid-Open
In JP-A-8-120265 and JP-A-61-155863, a configuration capable of solving the above-mentioned problem is not examined.

[0005]

In order to solve the above-mentioned problems, an image forming apparatus according to a first aspect of the present invention has an internal gear for rotational drive formed on a photosensitive drum, and a driving force meshing with the internal gear. In an image forming apparatus in which a transmission small-diameter gear is provided, and a process element for an image forming process for applying a pressing force to the photoconductor drum is provided around the photoconductor drum, the small-diameter gear is separated from the process element. Pressing force of
Each on both sides centered in the direction perpendicular to the direction of the resultant force
It is characterized in that it is provided in a 30 ° range .

According to a second aspect of the present invention, there is provided an image forming apparatus comprising:
2. The image forming apparatus according to claim 1, wherein the process comprises:
Centering around the direction perpendicular to the direction of the resultant force of the pressure contact force from the element
In the 30 ° range on both sides
The small diameter gear raises the position in the direction orthogonal to the direction of the resultant force.
It is characterized by being provided in a region on the direction side of the resultant force as a point .

The image forming apparatus according to the third aspect of the present invention provides
An internal gear for rotational drive is formed on the photoreceptor drum.
A small-diameter gear for driving force transmission meshing with the gear is provided.
Professional for image forming process to apply pressure to optical drum
Image type in which the process element is provided around the photosensitive drum
In the forming apparatus, the small-diameter gear is provided at a position in a direction orthogonal to a direction of a resultant force of the pressing force from the process element.

[0008]

[0009]

[0010]

[0011]

According to the first aspect of the present invention, the small-diameter gear meshing with the internal gear provided on the photosensitive drum is used in the image forming process.
Perpendicular to the direction of the resultant force of the crimping force from the process element
Since it is provided in the range of 30 degrees on both sides centered on the direction, wear of the internal gear and the small diameter gear is suppressed.
Can be Therefore, the internal gear, that is, the photosensitive drum can rotate smoothly, and the occurrence of image defects due to uneven rotation of the photosensitive drum can be prevented.

[0012]

[0013]

That is, if the small-diameter gear is provided in the region of the resultant force direction , the resultant force displaces the internal gear in a direction to increase the backlash . The other hand, the small-diameter gear is the case
3 on each side centered on the direction perpendicular to the direction of force
When the internal gear is displaced by the resultant force when the internal gear is provided in the range of 0 ° range , the change in the backlash is as described above.
Less than in the case of Thereby, wear of the internal gear and the small diameter gear can be suppressed.

According to the second aspect, since the small diameter gear, is provided in the direction of position direction Cartesian before Symbol force to the force direction of the region as a starting point, the internal gear Even when the resultant force is applied to the photosensitive drum, the photosensitive drum can rotate more favorably.

[0016] That is, the area of the resultant force direction originating from the direction of the position where the direction Cartesian before Symbol resultant force is the direction of the area where backlash is increased due to the resultant force. Therefore,
Interference between the non-drive surfaces of the internal gear and the small-diameter gear can be reliably prevented, and the photosensitive drum can rotate more favorably.

According to the configuration of claim 3, wherein the small diameter gear, so provided in the direction of the position where the direction Cartesian <br/> of the resultant force of the pressing force from said process elements, the inner most reliably Interference between the non-driving surfaces of the gear and the small diameter gear can be prevented.

[0018]

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, a copying machine as an image forming apparatus according to the present embodiment has a cylindrical photosensitive drum 1 inside. Around the photosensitive drum 1,
A main charger 2, a blank lamp 3, a developing device 4, a transfer charger 5, a peeling charger 6, a cleaning device 7, and a neutralizing lamp 8 are provided. An exposure device 9 is provided above the photosensitive drum 1. Each of these constitutes a process element for performing an image forming process.

The exposure apparatus 9 includes an exposure lamp 9a, a plurality of mirrors 9b,... And a lens 9c. A transparent document table 10 is provided on the exposure device 9. Further, the copying machine includes a transport belt 11, a fixing device 12, and a control unit 13.

When an image is formed by this copying machine, the original placed on the original table 10 is exposed by the exposure lamp 9a of the exposure device 9.
, And the reflected light is applied to the photosensitive drum 1 via a plurality of mirrors 9b and a lens 9c.
At this time, the photosensitive drum 1 is charged to a predetermined potential by the main charger 2 and is rotating at a constant speed in the direction of the arrow. Therefore, the photoreceptor drum 1 is irradiated with the reflected light to lower the potential of the light irradiation area, that is, is exposed, and an electrostatic latent image is formed on the surface of the photoreceptor drum 1. Further, the non-image area of the photosensitive drum 1 is discharged by light irradiation from the blank lamp 3.

The electrostatic latent image is developed with a developer supplied from a developing roller 4a of the developing device 4, that is, a toner, to form a toner image. The toner is agitated by the agitation roller 4b, so that the toner is charged in advance to a potential opposite to the charging potential of the photosensitive drum 1. The toner image is transferred onto a sheet (not shown) supplied between the photosensitive drum 1 and the transfer charger 5 by the transfer charger 5, and the sheet is separated from the surface of the photosensitive drum 1 by the separation charger 6. You. The sheet is transported to the fixing device 12 by the transport belt, and the toner image on the sheet is fixed on the sheet by the fixing device 12.

The transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is collected by the cleaning device 7, and the residual potential of the photosensitive drum 1 is removed by the discharging lamp 8. Further, toner is supplied from the toner hopper 14 to the developing device 4. This toner supply operation is performed based on a detection operation of a toner density sensor 15 provided in the developing device 4. The above image forming operation is performed under the control of the control unit 13.

The structure around the photosensitive drum 1 is shown in more detail in FIG. That is, the cleaning device 7 scrapes off the transfer residual toner on the surface of the photosensitive drum 1 by the cleaning blade 7a pressed against the surface of the photosensitive drum 1, and stores the scraped toner into a predetermined waste toner by the transport screw 7b. Unit. The discharging lamp 8 irradiates the photosensitive drum 1 with light via a filter 16 for preventing toner from adhering to the discharging lamp 8. The main charger 2, the transfer charger 5, and the peeling charger 6 are corona chargers that do not contact the photosensitive drum 1. A paper stop roller 17 that adjusts the sheet conveyance timing is provided on the side of the sheet that enters between the photosensitive drum 1 and the transfer charger 5. The peeling of the paper from the photosensitive drum 1 is performed by the peeling charger 6 and the peeling claw 18 in detail.

As shown in FIG. 3, the developing device 4 has a disk-shaped DSD (Drum Sleeve Discharge) at both ends of the developing roller 4a.
tance) collars 4c, 4c are provided, and these DSD collars 4c, 4c are arranged in pressure contact with the photosensitive drum 1, as shown in FIG. DSD collar 4c is slightly larger diameter than the developing roller 4a, thereby the state where the photosensitive drum 1 and the sleeve constituting the outer peripheral portion of the developing roller 4a is secured a certain small gap D _D Is held.

As shown in FIG. 5, the photosensitive drum 1 has
An internal gear, that is, an internal gear 21 is provided at one end thereof. In the present embodiment, the internal gear 21 also serves as a flange provided at an end of the photosensitive drum 1 and is made of resin. A pinion gear 23 as a small-diameter gear provided at one end of the rotating shaft 22 meshes with the internal gear 21. A gear 24 is provided at the other end of the rotating shaft 22.
Is geared with a gear 25 provided on a drive shaft 26a of a drum system drive motor 26.

In the copying machine, the photosensitive drum 1
Are pressed against the cleaning blade 7a of the cleaning device 7 and the DSD collar 4c of the developing device 4. In the present copying machine, as shown in FIG. 1, the pressure contact force of the photosensitive drum 1 by the cleaning blade 7a F _C, the pressure contact force of the photosensitive drum 1 by the DSD color 4c and F _D, these force the When F _O, the pinion gear 23 is provided in the direction of the position where the direction Cartesian of the resultant force F _O.

In the above configuration, during the image forming operation of the copying machine, the drum driving motor 26 shown in FIG.
Is transmitted to the drive shaft 26a, the gear 25, the gear 24, the rotating shaft 22, and the pinion gear 23, and the internal gear 21, that is, the photosensitive drum 1 rotates by being driven by the pinion gear 23 rotating at a fixed position. I do. On this occasion,
Photosensitive drum 1 is Cartesian to the direction of the resultant force F _O of the contact pressure F _C to the photosensitive drum 1 by the cleaning blade 7a, and pressing force F _D of the photosensitive drum 1 by the DSD color 4c Since the pinion gear 23 is provided in the direction, it can rotate smoothly. This is for the following reason.

[0029] Generally, in the design of the drive mechanism by the gear, when determining the center distance D _G of the gear shown in FIG. 6 is typically secured 10-20% of the size of the gear module as backlash . This dimension is generally called inter-axis backlash. That is, the theoretical inter-axis distance D _G ′ is given assuming that the module is m, the number of teeth of the first gear (pinion gear 23) meshing with each other is n ₁ , and the number of teeth of the second gear (internal gear 21) is n _2. , D _G ′ = m × (n ₁ + n ₂ ) / 2. In contrast, the center distance D _G of the design, when the inter-axial backlash and A, the _{D G = m × (n 1} + n 2) / 2-A. A is a value of 10 to 20% of m.

[0030] In the drive system given the inter-shaft backlash as described above, if the center distance D _G is changed by bending or the like by an external force, as shown in FIG. 7, the internal gear 21 and the pinion gear 23 A moderate minimum, that is, a backlash BL exists between the teeth on the opposite side to the rotation direction indicated by the arrow, ie, between the non-driving surfaces. Due to the presence of the backlash BL, the pinion gear 23 and the internal gear 21 smoothly mesh with each other, and the internal gear 21 rotates smoothly.

[0031] Here, in the configuration shown in FIG. 1, if the direction of the pinion gear 23 is force F _O when provided in the opposite direction, the center distance D _G is changed by the force F _O. This change is of the direction the direction of the center distance D _G is spread, i.e. the backlash is decreased. Accordingly, in this case, as shown in FIG. 8, the backlash is eliminated, and the non-driving surfaces of the internal gear 21 and the pinion gear 23 interfere with each other, so that the internal gear 21, that is, the photosensitive drum 1 cannot rotate smoothly. . As a result, image defects such as uneven pitch due to uneven rotation of the photosensitive drum 1 occur.

[0032] In contrast, as shown in FIG. 1, when the pinion gear 23 is provided in the direction of Cartesian to the direction of the resultant force F _O is the resultant force F _O photosensitive drum in the direction of the 1
There variation of the shaft distance D _G due to the displacement is very small. Therefore, as shown in FIG. 7, the backlash BL is in a secured state, and the internal gear 21,
That is, the photosensitive drum 1 can rotate smoothly. Thereby, it is possible to prevent an image defect caused by uneven rotation of the photosensitive drum 1.

Further, in the embodiment described above, although it is assumed that arranging the pinion gear 23 in the direction direction Cartesian of the resultant force F _O, which is the best position on disposing the pinion gear 23 It is shown. Therefore, in addition to this, there is an area where the pinion gear 23 can be disposed so as to prevent rotation unevenness due to the displacement of the photosensitive drum 1. Hereinafter, this region will be described.

First, considering the widest area in which the pinion gear 23 can be arranged, the area E ₀ is an area in which no more distortion than the inter-axis backlash given as an initial setting (the inter-axis backlash A) occurs. It is. In other words, when the pinion gear 23 is disposed in a region where a distortion equal to or more than the backlash between the shafts occurs due to the resultant force F _O , the non-driving surfaces of the internal gear 21 and the pinion gear 23 are connected to each other, as shown in FIG. Will interfere.

As described above, when the pinion gear 23 is provided in the direction opposite to the direction of the resultant force F _O , the backlash is eliminated and the non-driving surfaces of the internal gear 21 and the pinion gear 23 interfere with each other. . Therefore, the resultant force F
When The _O direction of the region of the opposite direction and En, area E ₁ other than the region En is the resultant force F _O is also present backlash participating, a pinion gear 23 can be disposed.
These areas En, area E ₁ is a range shown in FIG. 9, for example.

Further, 2 best position of the pinion gear 23 shown in the embodiment of Figure 1, shown in FIG. 9
Positions P ₁ · P ₁ . And these positions P ₁
The regions E ₂ and E ₂ within the predetermined range around the center P ₁ are also regions where the axial distance _DG is unlikely to change due to the resultant force F _{O according} to the above-described principle that the non-driving surfaces interfere with each other. . The region E ₂ · E ₂ is a region in the internal gear 21 which is defined as a first region centered on the direction of the resultant force F _O , that is, a region of (region E ₁ -region E ₂ · E ₂ -region En). , Resultant force F
The second and third regions of _O direction and each direction of Cartesian two directions centering, i.e. a region E ₂ · E _2, the resultant force F _O fourth around the direction opposite to the direction of The region, that is, the region En
It can also be described as the second and third regions in the case of dividing into the four regions. The area E ₂ is, for example, a region of each 30 ° range on both sides around the position P _1.

Further, the resultant force in the region E ₁ F _O direction of a region, a direction extending axial distance D _G by displacement of the photosensitive drum 1. For this reason, the backlash increases, and although the above-mentioned interference between the non-driving surfaces does not occur,
That is, although there is no problem in the rotation of the photosensitive drum 1, the meshing of the internal gear 21 and the pinion gear 23 in the height direction of the teeth is reduced, so that a problem that the wear of both gears is promoted occurs.

That is, the gear meshing height of the theoretical module m is 2 m. If the backlash between shafts is further provided by 10 to 20%, the meshing height is 1.8 to
It is 1.9m. In the case of a copying machine, etc., the theoretical mesh height of 8
About 0%, that is, 1.6 m is necessary, and if it exceeds this, the above-described problems occur. Therefore, it is desirable that the backlash is within (1.8 to 1.9 m) -1.6 m = 0.2 to 0.3 m, that is, at least within 0.3 m. Therefore, a region other than the region in the direction of the resultant force F _O in the region E ₁ is a more favorable region. Note that this region is considered to correspond to the above-described regions E ₂ and E ₂ .

In the region E ₂ , the region in the direction opposite to the direction of the resultant force F _O starting from the position P ₁ is a region in which the backlash is reduced. On the other hand, a region E _{3 in} the direction of the resultant force F _O starting from the position P ₁ is a region in the direction in which the backlash increases. Accordingly, in the region E _2, region E ₃ is a region more desirable as providing areas of the pinion gear 23.

As shown in FIG. 10, the main charger 2 and the transfer charger 5 shown in FIG. 1 are respectively connected to the main charging roller 31 and the peeling roller 32 which come into contact with the photosensitive drum 1, respectively.
As if provided, the contact pressure of these also need to be considered in addition to the pressing force F _D by pressing force F _C and DSD collar 4c by the cleaning blade 7a. That is, the pressing force of the main charging roller 31 is F
a, when the pressure contact force by the peeling roller 32 and Fb, taking into account the direction of resultant force F _O, the pinion gear 23 is provided, for example, the best position shown in FIG.

In the above embodiment, the resultant force F _O
Of it has become used to set the arrangement position of the pinion gear 23 direction as a reference, so the resultant force F _O is minimized, to set the arrangement position of each process element to be pressed against the photosensitive drum 1 You may. Such a configuration is as shown in FIG. Arrangement of the figure is one where the contact pressure F _D by DSD color 4c is smaller than that shown in FIGS. 1 and 10, in order to minimize the resultant force F _O, mainly the position of the developing device 4 Is moved to the peeling roller 32 side. Incidentally, such an arrangement, in another configuration the above configuration the contact pressure is relatively large developing device 4 is not pressed against the photosensitive drum 1, since the resultant force F _O can be brought close to 0 Especially effective.

The rotational load of the photosensitive drum 1 is DS
It is smaller than the pressing force from the D collar 4c, the cleaning blade 7a, and other process elements. Therefore, the position displacement vector of the photosensitive drum 1 indicated by reference numeral B in FIG. 1 due to the rotational load of the photosensitive drum 1 itself is negligible.

[0043]

As described above, in the image forming apparatus according to the first aspect of the present invention, the small-diameter gear meshing with the internal gear provided on the photoreceptor drum has a smaller pressing force from the process element.
30 ° range on both sides centered in the direction perpendicular to the
This is a configuration provided in the surrounding area.

As a result, no interference occurs between the non-drive surfaces of the internal gear and the small diameter gear, and wear of the internal gear and the small diameter gear is suppressed.
Can be controlled. Accordingly, the internal gear, that is, the photosensitive drum can be smoothly rotated, and the occurrence of image defects due to uneven rotation of the photosensitive drum can be prevented .

[0045]

[0046]

[0047]

[0048]

The image forming apparatus according to the second aspect of the present invention provides
In the image forming apparatus 1 of the invention, the small-diameter gear, a structure is provided in the direction of position direction Cartesian before Symbol force to the force direction of the region as a starting point.

Thus, the internal gear can rotate more favorably even when the resultant force is applied to the photosensitive drum, and the occurrence of image defects due to uneven rotation of the photosensitive drum can be more reliably prevented. This has the effect that it can be performed.

The image forming apparatus of the third aspect of the present invention, the small diameter gear is, the direction and direct the resultant force of the pressing force from said process elements
A structure provided in the direction of the position where the intersection.

Thus, the interference between the non-driving surfaces of the internal gear and the small-diameter gear can be most reliably prevented, and the occurrence of image defects due to uneven rotation of the photosensitive drum can be most reliably prevented. It has the effect of being able to.

[0053]

[0054]

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a schematic front view illustrating a configuration around a photosensitive drum of a copying machine as an image forming apparatus.

FIG. 2 is a schematic overall configuration diagram of a copying machine having the configuration shown in FIG.

FIG. 3 is a perspective view of the developing device shown in FIG.

FIG. 4 is an explanatory diagram showing a state in which the developing device is pressed against the photosensitive drum using the DSD color shown in FIG. 3;

FIG. 5 is a perspective view showing a rotation drive mechanism of the photosensitive drum shown in FIG.

6 is an explanatory view of the center distance D _G of the gear and the pinion gear inner shown in FIG.

7 is an explanatory diagram of a normal meshing state between the internal gear and the pinion gear shown in FIG. 1;

FIG. 8 is an explanatory diagram of a meshing state when there is no backlash between the internal gear and the pinion gear shown in FIG. 1;

9 is an explanatory diagram of an area where a pinion gear can be arranged in the copying machine shown in FIG. 1;

FIG. 10 is a schematic front view of the periphery of a photoconductor drum showing another example of the configuration shown in FIG. 1;

11 is a schematic front view showing the periphery of a photoconductor drum showing another example of the configuration shown in FIG. 10;

FIG. 12 is a schematic overall configuration diagram of a conventional copying machine.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 4 developing device (process element) 4c DSD color 7 cleaning device (process element) 7a cleaning blade 21 internal gear (internal gear) 23 pinion gear (small diameter gear) 31 main charging roller (process element) 32 peeling roller ( Process element)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Kitabatake 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Hideaki Kadowaki 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Yoshikazu Harada 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Inside Sharp Corporation (56) References JP-A-3-101756 (JP, A) JP-A-6-258983 (JP, A JP-A-5-333675 (JP, A) JP-A-57-49242 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/00 350-352 G03G 21/16 -21/18 G03G 15/00 550

Claims (3)

(57) [Claims] An internal gear for rotational driving is formed on a photosensitive drum, a small diameter gear for transmitting driving force meshing with the internal gear is provided, and a process element for an image forming process for applying a pressing force to the photosensitive drum. Is provided around the photosensitive drum, wherein the small-diameter gear is a combination of a pressing force from the process element.
3 on each side centered on the direction perpendicular to the direction of force
An image forming apparatus provided in an area of 0 ° range . 2. The resultant force of the press contact force from the process element.
30 ° range on both sides centered in the direction perpendicular to the
In the enclosed area, the small-diameter gear is in the direction of the resultant force.
The direction of the resultant force starting from the position in the direction orthogonal to
The image forming apparatus according to claim 1, wherein the image forming apparatus is provided in an area . 3. An internal gear for rotational drive is formed on the photosensitive drum.
And a small-diameter gear for driving force transmission that meshes with this internal gear
Image forming process that applies pressure to the photosensitive drum
Process elements around the photoreceptor drum
In the image forming apparatus described above, the small-diameter gear is provided at a position in a direction orthogonal to the direction of the resultant force of the pressing force from the process element.