JP2008191384A - Driving unit and image forming apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving unit making small or eliminating amount of a lubricant supplied to an interface between a worm gear and a worm wheel and suppressing sticking of suspended matter to the interface. <P>SOLUTION: The driving unit for an image holder is provided with; a driving source, a worm shaft rotating by being driven by the driving source, the worm gear provided coaxially with the worm shaft and covered by covering material with a structure in which carbon atoms are combined by SP3 hybrid orbitals, and the worm wheel engaging with the worm gear and the image holder holding an image provided coaxially to the rotational shaft of the worm wheel is driven. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving device and an image forming apparatus using the driving device.

JP 2000-298387 A Japanese Patent Laid-Open No. 01-197767 JP 2002-287570 A

  2. Description of the Related Art Conventionally, in an image forming apparatus in which a plurality of rotating bodies are arranged in parallel, a single drive source, a worm shaft that is driven and connected to the single drive source, and a worm corresponding to the plurality of rotating bodies. A plurality of worm gears provided coaxially with the shaft, and a worm wheel fixed to the rotation shafts of the plurality of rotating bodies and meshing with the worm gears, the worm shaft corresponding to one or two rotating bodies. There is known a drive system for an image forming apparatus, which is divided into divided shaft bodies and each divided shaft body is connected via a flexible connecting means (see Patent Document 1).

  A photosensitive member; a charging unit that charges the photosensitive member around the photosensitive member; an exposing unit that projects image light onto the photosensitive member; and a developing unit that visualizes the exposed electrostatic latent image; An image forming apparatus including a driving engagement portion disposed between a driving support side and a photosensitive member supporting shaft that supports the photosensitive member. There is known an image forming apparatus driving apparatus characterized in that an oil supply unit capable of immersing a part in a lubricant is provided and the viscosity of the lubricant is 300 to 650 cSt / 37.8 ° C. (Patent Document 2) reference).

  Further, in the image forming apparatus including the photoconductor, the photoconductor is rotatably supported by a support member on an outer peripheral surface thereof, and the support member and the photoconductor in a support portion between the support member and the photoconductor. An image forming apparatus is known in which at least one contact surface is coated with a fluorine-based resin (see Patent Document 3).

  The object of the present invention is to reduce the amount of lubricant supplied to the interface between the worm gear and the worm wheel or to reduce the amount of lubricant, and to suppress the adhesion of floating substances to the interface, and image formation using the same To provide an apparatus.

  That is, the invention described in claim 1 is provided with a drive source, a worm shaft driven and rotated by the drive source, a coaxial shaft with the worm shaft, and carbon atoms coupled by SP3 hybrid orbitals. A worm gear covered with a covering material having a structure and a worm wheel meshing with the worm gear, and driving an image holding body that holds an image provided coaxially with a rotation axis of the worm wheel. This is a drive device for the image carrier.

  The invention described in claim 2 is the drive device according to claim 1, wherein the covering material has a dynamic friction coefficient (JIS K 7125) with respect to the worm wheel of 0.14 or less.

  The invention described in claim 3 is the drive device according to claim 1, wherein the covering material has a coefficient of dynamic friction (JIS K 7125) with respect to the worm wheel of 0.1 or less.

  The invention described in claim 4 is the drive device according to claim 1, wherein the covering material is diamond-like carbon.

  The invention described in claim 5 is the drive device according to claim 1, wherein the covering material is tetrahedral amorphous carbon.

  The invention described in claim 6 is developed by the image carrier, a charger for charging the image carrier, a developer for developing the latent image formed on the image carrier, and the developing means. An image forming apparatus comprising: a transfer unit that transfers an image to a recording material; and the driving device according to claim 1.

  According to the first aspect of the present invention, the amount of lubricant supplied to the interface between the worm gear and the worm wheel can be reduced or omitted as compared with the case where the coating material of this configuration is not coated. Adherence of suspended matter is suppressed.

  According to the invention described in claim 2, even when the amount of lubricant supplied to the interface between the worm gear and the worm wheel is reduced or omitted, the sliding of the worm gear can be made smooth.

  According to the third aspect of the present invention, the sliding of the worm gear can be made smoother than the second aspect of the present invention.

  According to the fourth aspect of the present invention, the worm gear can be slid smoothly and wear of the worm gear can be suppressed as compared with the case where the coating material of this configuration is not coated.

  According to the fifth aspect of the present invention, compared with the fourth aspect of the present invention, the sliding of the worm gear can be further smoothed and the wear of the worm gear can be suppressed.

  According to the sixth aspect of the present invention, it is possible to suppress fluctuations in the rotational speed of the image carrier and to suppress the occurrence of image unevenness as compared with an image forming apparatus that does not use the drive device of this configuration. .

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

  1 to 4 are diagrams showing an embodiment of a drive device according to the present invention and an image forming apparatus using the drive device.

  FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present embodiment. In the image forming apparatus 10, image forming units 22 (specifically, 22 a to 22 d) of four colors (black, yellow, magenta, and cyan in this example) are arranged in a horizontal direction in a main body housing 21, and above that The intermediate transfer belt 23 that is circulated and conveyed along the direction in which the image forming units 22 are arranged is disposed in the recording medium, and a recording material (not shown) such as paper is accommodated below the main body housing 21. In addition to the supply cassette 24, a recording material conveyance path 25 serving as a recording material conveyance path from the recording material supply cassette 24 is arranged.

  Each of the image forming units 22 (22a to 22d) is, for example, toner for black, yellow, magenta, and cyan (arrangement is not necessarily in this order) in order from the upstream side in the circulation direction of the intermediate transfer belt 23. An image is formed, and each photoconductor cartridge 30 and one common exposure unit 40 are provided. Here, the photosensitive cartridge 30 includes, for example, a photosensitive drum 31 (image holding member), a charger (charging roll in this example) 32 that charges the photosensitive drum 31 in advance, and the charged photosensitive drum 31. A developing unit 33 for developing the electrostatic latent image exposed and formed by the exposure unit 40 with a corresponding color toner (eg, negative polarity in this example), and a cleaner 34 for removing residual toner on the photosensitive drum 31; Are integrated into a cartridge. Reference numeral 35 (35a to 35d) denotes a toner cartridge for replenishing each color component toner to the developing device 33 of each photoconductor cartridge 30. On the other hand, the exposure unit 40 includes, for example, four semiconductor lasers (not shown), one polygon mirror 42, an imaging lens (not shown), and mirrors (not shown) corresponding to the respective photosensitive cartridges 30 in the case 41. And the light from the semiconductor laser for each color component is deflected and scanned by the polygon mirror 42, and the light image is guided to the exposure point on the corresponding photosensitive drum 31 through the imaging lens and mirror. Is.

  When the development by the developing device 33 is a two-component development method, a carrier that charges the toner and carries it to the electrostatic latent image surface on the photosensitive drum 31 is mixed inside the developing device 33. Examples of the carrier include iron powder, ferrite particles, and ferrite particles coated with a resin for controlling charging. The average particle diameter of the carrier is, for example, about 30 μm, and the hardness is Vickers hardness (measured by a micro Vickers hardness test) of about 500 HV.

  Further, the transfer unit in the present embodiment includes the intermediate transfer belt 23, the primary transfer device 51, and the secondary transfer roll 521. For example, the intermediate transfer belt 23 is stretched between a pair of stretching rolls (one is a drive roll) 231 and 232, and the primary transfer belt 23 corresponding to the photosensitive drum 31 of each photosensitive cartridge 30 has a primary surface on the back surface thereof. A transfer device (primary transfer roll in this example) 51 is disposed, and a toner image on the photosensitive drum 31 is transferred to the intermediate transfer belt 23 by applying a voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roll 51. It is designed to electrostatically transfer to the side. Further, a secondary transfer device 52 is provided at a portion corresponding to the stretching roll 232 on the downstream side of the image forming unit 22d on the most downstream side of the intermediate transfer belt 23, and the primary transfer image on the intermediate transfer belt 23 is provided. Is transferred to a recording material by secondary transfer (collective transfer). In this embodiment, the secondary transfer device 52 is disposed on the side of the toner image holding surface of the intermediate transfer belt 23 so as to be in pressure contact with the secondary transfer roll 521, and is disposed on the back side of the intermediate transfer belt 23. A backup roll (which also serves as the stretching roll 232 in this example) is provided as a counter electrode of the transfer roll 521. For example, the secondary transfer roll 521 is grounded, and a bias having the same polarity as the charging polarity of the toner is applied to the backup roll 232. Furthermore, a belt cleaner 53 is provided on the upstream side of the image forming unit 22a on the most upstream side of the intermediate transfer belt 23 so that residual toner on the intermediate transfer belt 23 is removed.

  Further, the recording material supply cassette 24 is provided with a takeaway roll 61 for picking up the recording material, and immediately after the takeaway roll 61 is provided with a feed roll 62 for feeding the recording material, and immediately before the secondary transfer site. A registration roll 63 for supplying the recording material to the secondary transfer portion at a predetermined timing is provided in the recording material conveyance path 25 located in the position. Reference numeral 64 denotes a feed roll for sending a manual feeding recording material. On the other hand, a fixing device 66 is provided in the recording material conveyance path 25 located on the downstream side of the secondary transfer site, and a discharge roll 67 for discharging the recording material is provided on the downstream side of the fixing device 66. The discharged recording material is accommodated in an accommodation tray 68 formed in the upper part of the housing 21.

  Next, a driving device for a photosensitive drum (image holding member) used in the image forming apparatus 10 according to the present embodiment will be described. As shown in FIGS. 2 and 3, the drive device 100 has a single drive motor 120 (fixed and installed in this example), and a flexible cup is provided on the drive shaft 120 a of the drive motor 120. A worm shaft (rotation transmission shaft) 122 is coaxially connected via a ring 121, and a portion of the worm shaft 122 corresponding to the photosensitive drum 31 of each image forming unit 22 (22a to 22d) has a worm gear 125 ( Specifically, 125 a to 125 d) are attached, while a worm wheel 126 (specifically 126 a to 126 d) is coaxially attached to one end side of each photosensitive drum 31, and each worm wheel 126 and each worm gear 125 are attached. And are engaged with each other. In FIG. 3, reference numerals 311 and 312 denote bearings that support the photosensitive drums 31.

  The worm shaft 122 is supported by a pair of bearings 141 and 144, and a spring 147 is provided between one bearing 141 of the worm shaft 122 and the worm gear 125a.

  Examples of the material of the worm shaft 122 and the worm gear 125 include free-cutting stainless steel (SUS416). Examples of the material for the worm wheel 126 include polyacetal (POM) and polyether ether ketone (PEEK).

  Next, operations of the driving device 100 and the image forming apparatus 10 for the photosensitive drum 31 (image holding member) according to the present embodiment will be described. The driving device 100 for the photosensitive drum 31 operates as follows. 2 and 3, when a start switch (not shown) is turned on, the drive motor 120 rotates, the driving force is transmitted to the worm shaft 122 through the flexible coupling 121, and is provided coaxially with the worm shaft 122. As the worm gear 125 rotates, the worm wheel 126 meshing with the worm gear 125 rotates, and the photosensitive drums 31 of the image forming units 22 (22a to 22d) are driven.

  A toner image of each color component is formed on the photoconductive drum 31 driven in this way, and each color component toner image on each photoconductive drum 31 is transferred onto the intermediate transfer belt 23 by the transfer action of each primary transfer roll 51. The multiple transfer toner images on the intermediate transfer belt 23 are collectively transferred onto the recording material by the transfer action of the secondary transfer device 52. Thereafter, the recording material onto which the multiple transfer toner image has been transferred passes through the fixing device 66 and is then discharged to the storage tray 68.

  Further, the surface of the worm gear 125 of the driving device 100 of the image forming apparatus 10 according to the present embodiment is coated with a covering material 125a having a structure in which carbon atoms are bonded by SP3 hybrid orbits as shown in FIG. ing. Examples of the coating material having a structure in which carbon atoms are bonded by SP3 hybrid orbitals include diamond-like carbon (Diamond_Like Carbon: DLC), tetrahedral amorphous carbon (Tetrahedral Carbon: Ta-C), and the like. Diamond-like carbon is an amorphous substance having a structure in which carbon atoms are bonded by SP2 hybrid orbitals (SP2 structure) and a structure in which SP atoms are bonded by SP3 hybrid orbitals (SP3 structure). Tetrahedral amorphous carbon is a carbon atom. Is an amorphous material having an SP3 structure of 80% or more. Note that the proportion of the SP3 structure in the amorphous material is measured by X-ray analysis or Raman spectroscopy.

  Therefore, according to the image forming apparatus 10 of the present embodiment, the lubricant (grease, oil, etc.) supplied to the interface between the worm gear 125 and the worm wheel 126 can be reduced or omitted, and the image forming apparatus 10 can be omitted. It is possible to prevent floating floating substances such as carriers and dust from being trapped by the lubricant. As a result, the surface of the worm gear is prevented from being damaged by floating substances in the image forming apparatus 10 and fluctuations in the rotational speed of the photosensitive drum 31 driven by the worm gear 125 are suppressed, so that the density of the image transferred to the recording material is reduced. The occurrence of unevenness (image unevenness) is suppressed.

  In this embodiment, the worm gear 125 is formed by coating the surface of free-cutting stainless steel (SUS416) with diamond-like carbon (DLC), which is a coating material 125a. Diamond-like carbon was formed by plasma CVD. In this film forming method, a high frequency power is applied between two electrodes facing each other to generate a glow discharge therebetween, and the glow discharge is used to decompose the CH4 (methane) source gas introduced between the electrodes, A thin film is deposited on a substrate set on a cathode. The film formation temperature was about 200 ° C., the SP3 structure was 10 to 50%, the hardness was 1000 to 5000 HV (10 to 50 Gpa in the SI unit system), and the film thickness was about 1.5 μm. The hardness is Vickers hardness.

  The obtained diamond-like carbon had a coefficient of friction of 0.14 with respect to poceacetal. The friction coefficient is a dynamic friction coefficient measured according to JIS K 7125 (ISO 8295).

  FIG. 5 is a diagram showing fluctuations in the rotational speed of the photosensitive drum 31 driven by the worm gear in the image forming apparatus 10. An acceleration test was performed in which the carrier was forcibly applied to the worm wheel 126 to drive and rotate the worm shaft 122, and the rotational speed of the photosensitive drum 31 was measured. The ratio of the speed fluctuated with respect to the designed rotational speed of the photosensitive drum 31 was obtained as the rotational speed fluctuation rate. The horizontal axis represents the cumulative number of rotations of the photosensitive drum 31. The vertical axis represents the rotational speed fluctuation rate of the photosensitive drum 31.

  In the figure, “◆” indicates that the worm gear is free-cutting stainless steel (SUS416) (without covering material), the worm wheel 126 is polyacetal (Tenac LM511 manufactured by Asahi Kasei Corporation), and the interface between the worm gear and the worm wheel 126 It is a result when a lubricant (grease) is applied to (conventional example). Without the lubricant, the wear of the worm gear became too large to be measured, so the measurement was made by applying a lubricant. In addition, the Vickers hardness of SUS416 is 146HV.

  In the figure, “■” is the result when the worm gear is the worm gear 125 coated with the diamond-like carbon of this embodiment and the worm wheel 126 is polyacetal (Tenac LM511 manufactured by Asahi Kasei Corporation) (Example 1).

  According to the result of this experiment, in the case of Example 1, the surface of the worm gear 125 was not damaged as much as the conventional example. This is because in the first embodiment, carrier adhesion to the interface between the worm gear 125 and the worm wheel 126 is suppressed. Further, compared with the conventional example, the change in the rotational speed fluctuation rate in Example 1 was very small.

  In the case of the conventional example, density unevenness (image unevenness) that can be visually confirmed occurs in the image transferred to the recording material after the rotational speed of the photosensitive drum 31 is 290,000. On the other hand, in the case of Example 1, even after the rotational speed of the photosensitive drum 31 is 290,000, there is no occurrence of density unevenness (image unevenness) that can be visually confirmed in the image transferred to the recording material. It was.

  In this embodiment, the worm gear 125 is obtained by coating the surface of free-cutting stainless steel (SUS416) with tetrahedral amorphous carbon (Ta-C) as the coating material 125a. The tetrahedral amorphous carbon is formed by a FCVA (Filtered Cathodic Vacuum Arc) method. This film-forming method is different from the above-mentioned plasma CVD method in that plasma is formed by a solid evaporation material on the cathode side, and thus no gas for generating and maintaining a discharge is required. Taking Ta-C as an example, a pure graphite on the cathode side is discharged to generate an arc discharge to generate a carbon plasma. From the atoms, molecules and charged particles generated at this time, high energy is generated by an electromagnetic space filter. Only ionized carbon is extracted and deposited on a substrate. The film forming temperature is about 20 to 80 ° C., the SP3 structure is 80% or more, the hardness is 6000 to 9000 HV (SI unit system 60 to 90 Gpa), and Ta—C is formed so that the film thickness is about 1.5 μm. Filmed. The hardness is Vickers hardness.

  Moreover, the friction coefficient with respect to the polyacetal of the tetrahedral amorphous carbon used in the present Example was 0.1. The friction coefficient is a dynamic friction coefficient measured according to JIS K 7125 (ISO 8295).

  In FIG. 5, “▲” indicates the result when the worm gear is the worm gear 125 covered with the tetrahedral amorphous carbon of this embodiment and the worm wheel 126 is polyacetal (Tenac LM511 manufactured by Asahi Kasei Corporation) (Example 2). It is. The rotational friction fluctuation rate was measured in the same manner as in Example 1.

  According to the result of this experiment, the surface of the worm gear 125 was hardly changed even before the test. Further, in the case of the present embodiment as compared with Embodiment 1, the change in the rotational speed fluctuation rate was further minute.

  In the case of the present embodiment, as in the first embodiment, even after the rotational speed of the photosensitive drum 31 is 290,000, the density unevenness that can be visually confirmed in the image transferred to the recording material ( There was no occurrence of image unevenness.

  In addition, this invention is not limited to the said embodiment and Example, A various deformation | transformation implementation is possible within the range of the summary of this invention.

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the embodiment. FIG. 2 is a diagram illustrating a driving device of the image forming apparatus according to the embodiment. FIG. 3 is an arrow view seen from the direction of arrow IV in FIG. FIG. 4 is a cross-sectional view illustrating a worm gear of the driving device of the image forming apparatus according to the embodiment. FIG. 5 is a diagram illustrating fluctuations in the rotational speed of the photosensitive drum that is rotationally driven by the worm gear in the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Image forming apparatus, 31: Photosensitive drum (image holding body), 100: Drive apparatus, 120: Drive motor (drive source), 122: Worm shaft, 125: Worm gear, 125a: Coating material, 126: Worm wheel

It is an object of the present invention, the worm gear and the worm wheel and the interface for supplying the lubricant can be omitted or a small amount of the image forming apparatus adhesion of suspended matter to the interface using the driving equipment is suppressed Is to provide.

That is, the invention described in claim 1 is provided with a drive source, a worm shaft driven and rotated by the drive source, a coaxial shaft with the worm shaft, and carbon atoms coupled by SP3 hybrid orbitals. a worm gear that is coated with a coating material having a have structure, said worm gear and provided with a worm wheel, the meshing, the worm wheel rotational shaft and the image carrier that drive the image holding body that holds an image provided coaxially of the An image carrier, a charger for charging the image carrier, a developer for developing a latent image formed on the image carrier, and an image developed by the developing means as a recording material. And an image forming apparatus .

A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the coating material has a coefficient of dynamic friction (JIS K 7125) with respect to the worm wheel of 0.14 or less.

A third aspect of the present invention is the image forming apparatus according to the first aspect, wherein the covering material has a dynamic friction coefficient (JIS K 7125) with respect to the worm wheel of 0.1 or less.

The invention described in claim 4 is the image forming apparatus according to claim 1, wherein the covering material is diamond-like carbon.

The invention described in claim 5 is the image forming apparatus according to claim 1, wherein the covering material is tetrahedral amorphous carbon.

According to the first aspect of the present invention, the amount of lubricant supplied to the interface between the worm gear and the worm wheel can be reduced or omitted as compared with the case where the coating material of this configuration is not coated. Adherence of floating substances can be suppressed, fluctuations in the rotation speed of the image carrier can be suppressed, and occurrence of image unevenness can be suppressed.

That is, The invention described in claim 1, a driving source, a worm shaft which rotates driven by the driving source, the provided worm shaft coaxially and in between carbon atoms are bonded by SP3 hybrid orbital a worm gear that is coated with a coating material having a have structure, and a worm wheel meshing without passing through the worm gear and a lubricant, having said worm wheel at one end of the rotary shaft, is driven to rotate by the rotation of the worm gear an image holding member, a charging unit for charging the image holding member, wherein the latent image formed by exposure on the charged the image carrier on the charger, the developing means for developing with a developer, said developing means An image forming apparatus comprising: a transfer unit that transfers the image developed in step 1 to a recording material.

Claims (6)

A driving source;
A worm shaft driven and rotated by the drive source;
A worm gear provided coaxially with the worm shaft and covered with a coating material having a structure in which carbon atoms are bonded by SP3 hybrid orbits;
A worm wheel meshing with the worm gear,
An image holding member driving apparatus for driving an image holding member for holding an image provided coaxially with a rotating shaft of the worm wheel.   The drive device according to claim 1, wherein the covering material has a dynamic friction coefficient (JIS K 7125) with respect to the worm wheel of 0.14 or less.   The drive device according to claim 1, wherein the covering material has a dynamic friction coefficient (JIS K 7125) with respect to the worm wheel of 0.1 or less.   The drive device according to claim 1, wherein the covering material is diamond-like carbon.   The drive device according to claim 1, wherein the covering material is tetrahedral amorphous carbon. An image carrier,
A charger for charging the image carrier;
A developing unit for developing the latent image formed on the image carrier;
Transfer means for transferring the image developed by the developing means to a recording material;
A driving device according to any one of claims 1 to 5;
An image forming apparatus comprising:

Images