JP2019108985A - Image formation device - Google Patents

Abstract

To provide an image formation device capable of suppress from concentrating on a gear tooth root even when a module is made smaller than before.SOLUTION: An image formation device comprises a developing motor gear 105 and a developing speed reducing gear 104, and a driving part which transmits driving force to the developing motor gear 105, and is so constituted that the developing speed reducing gear 104 is formed to be less in torsional rigidity in a tooth width direction M from one side to the other in the tooth width direction M, the developing motor gear 105 and developing speed reducing gear 104 constituting the image formation device which has a twisting direction of helical teeth and a direction of rotation of the developing motor gear 105 by the driving part so set that the other side in the tooth width direction M comes into contact earlier than the one side.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus such as, for example, a copying machine or a printer, which has a function of forming an image on a recording material such as a sheet.

  Patent Document 1 discloses a configuration in which an annular rib is disposed between a central portion of a gear and a tooth surface portion, and is disposed at an interval such that the tooth surface portion and the annular rib do not contact. According to such a configuration, since the tooth surface portion and the annular rib are not in contact with each other, the portion of the tooth surface portion in contact with the annular rib is deformed under the influence of contraction during molding, and the tooth The phenomenon that the accuracy of the surface portion deteriorates is suppressed.

  If this configuration is used, the rotational fluctuation or vibration of the image forming unit causes positional fluctuation due to the rotational fluctuation or vibration of the imaging unit, resulting in periodic band-like uneven density unevenness called a banding image. Is considered to be prevented.

JP-A-9-230657

  However, the invention described in Patent Document 1 can not cope with the reduction of gears and the reduction of modules for achieving the recent downsizing of the device body. It is difficult to reduce the size of the module if the gear is reduced. If the module is small, the stress applied to the gear tooth root increases.

  Among these, in the configuration described in FIG. 3 of Patent Document 1, the inventor described that the portion of the arm formed between the tooth surface portion and the rotation support portion is disposed at the center in the width direction. I focused on it. It has been found that by changing the arrangement of the arms, it is possible to reduce the stress applied to the gear root while reducing the module.

  An object of the present invention is to provide an image forming apparatus capable of suppressing concentration of stress on a gear tooth base even if the module is reduced as compared with the conventional one in order to solve the above-mentioned problems.

  In order to achieve the above object, the image forming apparatus of the present invention comprises a first helical gear and a second helical gear in contact with each other, and a drive unit for applying a driving force to the first helical gear. At least one of the first helical gear and the second helical gear is formed such that the torsional rigidity in the tooth width direction decreases from one side to the other in the tooth width direction, and the first helical tooth is formed. The helical direction of the helical teeth and the rotation of the first helical gear by the drive unit such that the other of the gear and the second helical gear contacts the other in the width direction earlier than the one. A direction is set.

  According to the present invention, it is possible to suppress concentration of stress on the gear tooth base even if the module is reduced as compared with the conventional case.

FIG. 1 is a schematic cross-sectional view showing an outline of an image forming apparatus in the present invention. FIG. 6A is a schematic view showing a connection state of a motor to a photosensitive drum and an intermediate belt unit, and FIG. 6B is a schematic view of a drive configuration of a developing device. It is the schematic of arrangement | positioning of the gear in the drive structure of the image development apparatus shown in FIG.2 (b). FIG. 6 is a perspective view showing details of a developing motor gear and a developing reduction gear. FIG. 5 is a cross-sectional view of a developing motor gear and a developing reduction gear. It is a perspective view which shows the calculation result of the contact state of a tooth. It is a perspective view with a numerical value which shows the calculation result of the maximum stress in the development reduction gear, and its generation | occurrence | production location. FIG. 7 is a cross-sectional view of a developing motor gear and a developing reduction gear according to a second embodiment. FIG. 14 is a cross-sectional view of a developing motor gear and a developing reduction gear according to a third embodiment.

  Hereinafter, with reference to the drawings, a mode for carrying out the present invention will be exemplarily described in detail based on examples. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, so there is no particular description. As long as the scope of the invention is not limited to them, the scope of the invention is not limited thereto. Moreover, what attached | subjected the same code | symbol in each figure has the same structure or effect | action, and the overlapping description about these was abbreviate | omitted suitably.

  FIG. 1 is a schematic cross-sectional view showing an outline of an image forming apparatus 50 in the present invention. In the following description, yellow, magenta, cyan, and black are meant for those in which Y, M, C, and K are added to the code at each station, and in the following description, Y in the suffix of the code is used. , M, C and K are omitted. The image forming apparatus 50 of FIG. 1 is an example of a full-color image forming apparatus (a multi-functional peripheral having both a copying machine, a printer function, and a fax function). In FIG. 1, the image forming apparatus 50 has a plurality of, in the present embodiment, four image forming stations arranged side by side in the image forming apparatus main body (hereinafter, referred to as “apparatus main body 50A”). Are

  Each station includes a drum-shaped electrophotographic photosensitive member (shown as "photosensitive drum 10" in the present specification) as an "image carrier". In the present embodiment, the photosensitive drum 10 sequentially shares the yellow (Y) component, the magenta (M) component, the cyan (C) component, and the black (K) component of the color image. The photosensitive drums 10 are rotationally driven at a predetermined process speed in the direction of arrow A (counterclockwise) by a drum motor (not shown).

  Around the photosensitive drum 10, a charging device 11, a scanner unit 12, a developing device 13, an intermediate belt unit 14, a cleaning device 15, and the like are disposed in order according to the rotation direction. The charging device 11 (charging means) uniformly charges the surface of the photosensitive drum 10. The scanner unit 12 (exposure unit) irradiates a laser beam based on image information to form an electrostatic image on the photosensitive drum 10.

  The developing device 13 as “developing means” develops the electrostatic image on the surface of the photosensitive drum 10 with toner to generate a developer image (toner image). The intermediate belt unit 14 (electrostatic transfer unit) transfers the toner image on the photosensitive drum 10 to paper. The cleaning device 15 (cleaning means) removes transfer residual toner remaining on the surface of the photosensitive drum 10 after transfer.

  Hereinafter, an image forming station of yellow (Y) among the four colors will be described as an example. The photosensitive drum 10Y is uniformly charged to a predetermined polarity and potential by the charging device 11Y in the process of its rotation. Then, the photosensitive drum 10Y is exposed to a light image by the laser scanner 12Y, and an electrostatic image of the image information is formed on the photosensitive drum 10Y.

  Next, the electrostatic image formed on the photosensitive drum 10Y is visualized by the developing device 15Y to be a toner image. Subsequently, the toner image on the photosensitive drum 10 is transferred onto the intermediate belt unit 14 by the primary transfer roller 16Y. Thereafter, the toner image on the intermediate belt unit 14 is transferred by the secondary transfer roller 17 onto paper or other output. Similar steps are performed for the other three color (magenta (M), cyan (C) and black (Bk)) imaging stations, respectively.

[Drive]
Next, a driving device of an image forming unit for driving the photosensitive drum 10, the intermediate belt unit 14 and the developing device 13 provided with a drive transmission device which is a feature of the present invention will be described.

  FIG. 2A is a schematic view showing a connection state of the motors 100 and 101 to the photosensitive drum 10 and the intermediate belt unit 14. As shown in FIG. 2A, the photosensitive drums 10Y, 10M, and 10C are driven by the motor 100, and the photosensitive drum 10K and the intermediate belt unit 14 are driven by the motor 101.

  FIG. 2B is a schematic view showing the connection state of the motor 102 to the developing device 13. As shown in FIG. 2B, the developing devices 13Y, 13M, 13C, and 13K are driven by the motor 102.

  FIG. 3 is a schematic view of the gear arrangement in the drive configuration of the developing device 13 shown in FIG. 2 (b). As shown in FIG. 3, the developing device 13 is driven by a developing drive gear 103 provided coaxially with the input position of the drive. A DC brushless motor is often used as the motor 102, and generally used at about 2000 to 3000 rpm from the viewpoint of efficiency.

  Further, since the rotational speed of the developing device 13 is often used at about 100 to 500 rpm, the speed is reduced by the gear ratio of the development reduction gear 104, the development motor gear 105, and the development drive gear 103. If the arrangement is such that one motor rotates a plurality of rotation targets as in this configuration, a larger load is concentrated on the development reduction gear 104 as compared with a configuration in which one rotation target is driven by one motor.

  FIG. 4A is a perspective view showing the details of the developing motor gear 105 and the developing reduction gear 104. FIG. 4 (b) is a view as seen from the back side of FIG. 4 (a). The shapes of the developing motor gear 105 and the developing reduction gear 104 corresponding to the drive gear of this embodiment will be described in detail with reference to FIG. 4 and the like.

  A motor 102 is provided as a “driving unit” that drives the developing motor gear 105 of the developing device 13. The driving force of the motor 102 is transmitted to the developing device 13 via the drive transmission means. The developing motor gear 105 as the "first helical gear" and the development reduction gear 104 as the "second helical gear" are arranged to be in contact with each other, and the driving force from the development motor gear 105 to the development reduction gear 104 is It is transmitted.

  When FIG. 4A is viewed from the upper side, the developing motor gear 105 is formed by right-twisting helical teeth because the teeth are cut in the direction from the lower left to the upper right. Further, since the direction of the teeth of the development reduction gear 104 is cut in the direction from the lower right to the upper left, the development reduction gear 104 is formed of a left-handed helical tooth. In this way, the teeth of the helical teeth in contact with each other are combined in the opposite direction, that of right-handed and left-handed ones.

  As shown in FIG. 4A, the developing motor gear 105 is directly geared and formed on a metal drive shaft 102X of a motor 102 as a "motor" for generating a driving force. Therefore, the developing motor gear 105 is formed of metal as a whole.

  As shown in FIG. 4B, the development reduction gear 104 meshes with the development motor gear 105. The development reduction gear 104 is made of resin and has a rim 104c with teeth formed on its outer periphery, a boss 104d which is the rotational center of the rim 104c (simultaneously forming a rotational center of the gear), a rim 104c and a boss 104d. And a connecting web 104e.

  Also, ribs 104f and 104g project from the surface of the web 104e. The rib 104 f is extended radially (radially) (in a direction away from the boss 104 d) from the boss 104 d to reinforce the development reduction gear 104. The rib 104g is disposed concentrically with the boss 104d. The rib 104f is disposed at a predetermined distance from the rim 104c in order to prevent deterioration of the tooth surface accuracy due to shrinkage at the time of molding, and has a shape that does not contact each other.

  FIG. 5 is a cross-sectional view of the developing motor gear 105 and the developing reduction gear 104. The web 104 e is provided on the front side 104 a of the development reduction gear 104. From this, the position of the web width direction M of the web 104e is disposed at the left end position deviated from the center M1 of the tooth width direction M. The tooth width direction M mentioned here means the thickness direction of the gear.

  Therefore, the torsional rigidity in the tooth width direction M is inclined so that the front side 104a of the development reduction gear 104 is large and the rear side 104b is small. That is, the torsional rigidity in the tooth width direction M of the development reduction gear 104 is configured to become smaller as going from the front side 104a (one side) in the tooth width direction M to the rear side 104b (the other side). In other words, the torsional rigidity in the tooth width direction M decreases as the web 104 e moves from the side in the tooth width direction M toward the side not in the tooth width direction M. Note that at least one of the developing motor gear 105 and the developing reduction gear 104 may be configured as such.

  Here, referring back to FIG. Then, the developing motor gear 105 rotates in the arrow A direction, and the meshing development reducing gear 104 rotates in the arrow B direction. The helical gear has the property of coming into contact with the other gear from the leading side in the rotational direction.

  That is, the helical gear contacts the other gear in order from the one of the rotating helical teeth advancing in the advancing direction. That is, since the developing motor gear 105 is formed to be right-handed and rotates in the direction of arrow A, the back end 105X2 of the helical tooth 105X rotates in the direction of arrow A earlier than the front end 105X1. Further, since the development reduction gear 104 is formed in a left-handed twist and rotates in the arrow B direction, the back end 104X2 of the helical tooth 104X rotates in the arrow B direction earlier than the front end 104X1. Therefore, both the developing motor gear 105 and the developing reduction gear 104 come in contact with the other gear from the side of the back end 105X2 or 104X2 which is moving in the direction of travel.

  In the configuration of the present embodiment, the direction of the helical teeth is set to contact from the back side 104b having a small torsional rigidity. That is, in the developing motor gear 105 and the developing reduction gear 104, the teeth having the smaller torsional rigidity (the other in the tooth width direction) contact each other earlier than the side having the torsional rigidity (the other in the tooth width direction). The helical direction of the helical teeth and the rotational direction of the developing motor gear 105 by the motor 102 are set.

  A simulation experiment was conducted to observe the contact state of the teeth of the present embodiment configured as described above and to calculate the maximum value of the root stress. The simulation experiment used Abaqus which is general purpose nonlinear structure analysis software. The developing motor gear 105 is a rigid body, and the developing reduction gear 104 is an elastic body having a Young's modulus of 2200 MPa. The gear module is 0.4, the twist angle is 20 °, the pressure angle is 20 °, the number of teeth of the developing motor gear 105 is 11, the number of teeth of the development reduction gear 104 is 86, and the driving load is 0.8 N · m. Thus, the number of teeth of the development motor gear 105 is set smaller than the number of teeth of the development reduction gear 104.

  FIG. 6 is a perspective view showing the calculation result of the contact state of the teeth when the development reduction gear 104 rotates in the arrow B direction. Incidentally, in order to make the contact state easy to see, the developing motor gear 105 displays only the tooth surface in contact. Also, although the development reduction gear 104 in FIG. 6 looks like a spur gear, it has a left twisting helical tooth in which a twist is formed to the left with respect to the axis as described above. When the actual lotus tooth is enlarged, it looks like FIG.

  In FIG. 6, the portion in contact is indicated by a black portion K. The development reduction gear 104 rotates in the direction of arrow B in the order of FIGS. As the helical teeth 105X of the developing motor gear 105 rotate, they come into contact with the development reduction gear 104 sequentially from the side of the back end 105X2 which is the forward side of the helical teeth. The contact area between the developing motor gear 105 and the developing reduction gear 104 is shifted from the back end 104X2 of the developing reduction gear 104 to the front end 104X1. Further, it can be seen that, in the developing motor gear 105, three helical teeth 105X are always in contact with the developing reduction gear 104 during rotation.

  6 (d), 6 (e) and 6 (f) are for comparison with the present embodiment, and the development deceleration in the direction of the arrow C, which is the opposite direction to FIGS. 6 (a), 6 (b) It is a perspective view which shows the calculation result of the contact state of the teeth when the gear 104 rotates. The rotation of the helical teeth 105X of the developing motor gear 105 is reversed, and the advancing direction of the helical teeth is also reversed, and contacts the developing reduction gear 104 sequentially from the front end 105X1 side. Then, in the developing motor gear 105, the number of helical teeth 105X in contact with the developing reduction gear 104 during rotation is reduced to two.

  Comparing these two examples, the developing motor gear 105 is always in contact with the developing motor gear 105 because the deformable portion of the development reduction gear 104 is in contact in the rotational direction of the present embodiment, since the contact is from the side with low torsional rigidity. Will increase. On the other hand, in rotation in the opposite direction, contact is made from the side with high torsional rigidity on the front side 104a, and therefore the developing motor gear 105 is in contact with the less deformable portion of the development reduction gear 104 and teeth which are always in contact are reduced.

  FIG. 7 is a perspective view with numerical values showing the calculation results of the maximum stress in the development reduction gear 104 and the point of occurrence thereof. It represents that the stress is higher in the order of the shaded portion K2 and the shaded portion K1. FIG. 7 (a) is the calculation result of the rotation direction (arrow B direction) of the present embodiment corresponding to FIGS. 6 (a), 6 (b) and 6 (c). FIG. 7 (b) is the calculation result of the rotation direction (arrow C direction) opposite to that of the present embodiment corresponding to FIGS. 6 (d), 6 (e) and 6 (f).

  The stress value is represented by the maximum principal stress. The point of occurrence of the maximum stress is the tooth root near the front side 104a where the torsional rigidity is large. Assuming that the maximum stress value is 1 in this example (FIG. 7A), the opposite direction rotation (FIG. 7B) is 2.3.

  In the present embodiment (see FIG. 7A), the number of tooth contact, that is, the contact area for receiving a load, is large by rotation of the development reduction gear 104 in the direction of the arrow B. The smaller the stress value is, the smaller the maximum stress is 84.5 MPa. On the other hand, in the comparative example (see FIG. 7B), when the development reduction gear 104 rotates in the direction of arrow C, the number of contact of the teeth, ie, the contact area receiving load, is small. As the relative stress increases, the stress value increases and the maximum stress also increases to 194 MPa.

  According to this embodiment, when transmitting a large load with a small module, the rigidity is increased in order to secure the strength, and the deterioration of the tooth surface accuracy due to shrinkage at the time of molding is not caused, so a high quality image without banding image A drive configuration capable of outputting can be provided.

  FIG. 8 is a cross-sectional view of the developing motor gear 105 and the developing reduction gear 104 according to the second embodiment. The second embodiment differs from the configuration of the first embodiment only in the configuration in which the gradient in torsional rigidity in the tooth width direction M of the development reduction gear 104 is different, and therefore the description of the same configuration will be omitted.

  The thickness of the rim 104c of the development reduction gear 104 is thinner as it goes from the front side 104a (one side) in the tooth width direction M to the rear side 104b (the other side). For this reason, the torsional rigidity in the tooth width direction M has a slope that is large on the front side 104 a and small on the back side 104 b. Thus, the torsional rigidity in the tooth width direction M of the development reduction gear 104 is configured to become smaller as going from the front side 104a (one side) in the tooth width direction M to the rear side 104b (the other side). In other words, the torsional rigidity in the lateral direction M decreases as the thickness of the rim 104 c increases from the thick side to the thin side of the rim 104 c.

  FIG. 9 is a cross-sectional view showing the details of the developing motor gear 105 and the developing reduction gear 104 of the third embodiment. The present embodiment is different from the first embodiment only in the configuration in which the torsional rigidity in the tooth width direction M of the development reduction gear 104 is inclined. Therefore, the description of the same configuration will be omitted.

  Here, in the development reduction gear 104, a web 104e is formed between the boss 104d and the rim 104c. The web 104 e is disposed substantially at the center in the tooth width direction M of the development reduction gear 104. The web 104 e is formed in a plate shape in a disk shape around the boss 106.

  On the premise of this configuration, the rib 104f extends radially from the boss 104d (this point is the same as FIG. 4 (b)) and protrudes from the web 104e toward the front side 104a (this point is This is different from FIG. 4 (b)). Thus, the rib 104 f is disposed only on the front side 104 a (one side) in the tooth width direction M. For this reason, the torsional rigidity in the tooth width direction M has a slope that is large on the front side 104 a and small on the back side 104 b.

  Thus, the torsional rigidity in the tooth width direction M of the development reduction gear 104 is configured to become smaller as going from the front side 104a (one side) in the tooth width direction M to the rear side 104b (the other side). In other words, the torsional rigidity in the tooth width direction M decreases as it goes from the side where the rib 104 f is disposed to the side where the rib 104 f is not disposed.

  According to the configuration of any one of the first to third embodiments, it is possible to suppress concentration of stress on the gear tooth base even if the module is reduced as compared with the related art.

50 image forming apparatus 104 developing reduction gear (second helical gear)
105 Development motor gear (first helical gear)
M Tooth width direction

  In order to achieve the above object, an image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet, and a driving force transmission unit that transmits a driving force to the image forming unit. The driving force transmission unit is a first helical gear, a second helical gear meshing with the first helical gear, and a rim having an outer peripheral portion on which a plurality of teeth are formed, and the second helical gear From a boss serving as a rotation center of a tooth gear, a web provided on one end side with respect to the center of the rim in the tooth width direction of the second helical gear, and connecting the rim and the boss; A second helical gear having a plurality of ribs projecting in the tooth width direction of the helical gear, extending from the boss toward the rim and spaced apart from the rim; 1st lotus tooth In the gear and the second helical gear, the contact portion between the first helical gear and the second helical gear transitions from the other end opposite to the one end in the tooth width direction to the one end It is characterized in that it is rotated to transmit a driving force to the image forming unit.

Claims (8)

A first helical gear and a second helical gear contacting each other;
A driving unit for applying a driving force to the first helical gear;
Equipped with
At least one of the first helical gear and the second helical gear is formed such that the torsional rigidity in the tooth width direction decreases from one to the other in the tooth width direction.
The helical direction of the helical teeth and the first by the driving portion so that the other of the first helical gear and the second helical gear contacts the other in the tooth width direction earlier than the one. An image forming apparatus characterized in that a rotational direction of a helical gear is set. At least one of the second helical gear and the first helical gear comprises: a rim having teeth formed on an outer periphery; a boss as a rotation center of the rim; and a web connecting the rim and the boss; Have
The position of the web in the tooth width direction is disposed at a position deviated from the center in the tooth width direction, and the tooth width is increased from the side where the web is inclined in the tooth width direction toward the side where the web is not The image forming apparatus according to claim 1, wherein the torsional rigidity in the direction is reduced. At least one of the second helical gear and the first helical gear comprises: a rim having teeth formed on an outer periphery; a boss as a rotation center of the rim; and a web connecting the rim and the boss; Have
The thickness of the rim is formed to be thinner as it goes from one side to the other in the width direction, and the torsional rigidity in the width direction decreases as the thickness of the rim increases from the thicker side to the thinner side. The image forming apparatus according to claim 2, wherein The second helical gear has a plurality of ribs projecting in the tooth width direction from the surface of the web and radially extending about the boss.
The rib is disposed only on one side when viewed from the center in the width direction, and not disposed on the other side when viewed from the center in the width direction,
The image forming apparatus according to claim 2, wherein the torsional rigidity in the width direction decreases as it goes from the side where the ribs are arranged to the side where the ribs are not arranged.   The image forming apparatus according to any one of claims 1 to 4, wherein the second helical gear is formed of resin, and the first helical gear is formed of metal.   The image forming apparatus according to claim 5, wherein the number of teeth of the first helical gear is set smaller than the number of teeth of the second helical gear.   The image forming apparatus according to claim 6, wherein the first helical gear is toothed off at a drive shaft of a motor generating a drive force. An image carrier,
Developing means for developing the electrostatic image on the surface of the image carrier with toner;
Have
The image forming apparatus according to claim 7, wherein the motor is the drive unit that drives the first helical gear.

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